&EPA
United States October 2006
Environmental Prolecllon EPA/600/R-05/144bF
Air Quality Criteria for Lead
Volume II of II
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EPA/600/R-05/144bF
October 2006
Air Quality Criteria for Lead
Volume II
National Center for Environmental Assessment-RTF Division
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, NC
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PREFACE
National Ambient Air Quality Standards (NAAQS) are promulgated by the United States
Environmental Protection Agency (EPA) to meet requirements set forth in Sections 108 and 109
of the U.S. Clean Air Act. Those two Clean Air Act sections require the EPA Administrator
(1) to list widespread air pollutants that reasonably may be expected to endanger public health or
welfare; (2) to issue air quality criteria for them that assess the latest available scientific
information on nature and effects of ambient exposure to them; (3) to set "primary" NAAQS to
protect human health with adequate margin of safety and to set "secondary" NAAQS to protect
against welfare effects (e.g., effects on vegetation, ecosystems, visibility, climate, manmade
materials, etc); and (5) to periodically review and revise, as appropriate, the criteria and NAAQS
for a given listed pollutant or class of pollutants.
Lead was first listed in the mid-1970's as a "criteria air pollutant" requiring NAAQS
regulation. The scientific information pertinent to Pb NAAQS development available at the time
was assessed in the EPA document Air Quality Criteria for Lead; published in 1977. Based on
the scientific assessments contained in that 1977 lead air quality criteria document (1977 Lead
AQCD), EPA established a 1.5 |ig/m3 (maximum quarterly calendar average) Pb NAAQS in
1978.
To meet Clean Air Act requirements noted above for periodic review of criteria and
NAAQS, new scientific information published since the 1977 Lead AQCD was later assessed in
a revised Lead AQCD and Addendum published in 1986 and in a Supplement to the 1986
AQCD/Addendum published by EPA in 1990. A 1990 Lead Staff Paper, prepared by EPA's
Office of Air Quality Planning and Standards (OPQPS), drew upon key findings and conclusions
from the 1986 Lead AQCD/Addendum and 1990 Supplement (as well as other OAQPS-
sponsored lead exposure/risk analyses) in posing options for the EPA Administrator to consider
with regard to possible revision of the Pb NAAQS. However, EPA chose not to revise the Pb
NAAQS at that time. Rather, as part of implementing a broad 1991 U.S. EPA Strategy for
Reducing Lead Exposure, the Agency focused primarily on regulatory and remedial clean-up
efforts to reduce Pb exposure from a variety of non-air sources that posed more extensive public
health risks, as well as other actions to reduce air emissions.
The purpose of this revised Lead AQCD is to critically assess the latest scientific
information that has become available since the literature assessed in the 1986 Lead
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AQCD/Addendum and 1990 Supplement, with the main focus being on pertinent new
information useful in evaluating health and environmental effects of ambient air lead exposures.
This includes discussion in this document of information regarding: the nature, sources,
distribution, measurement, and concentrations of lead in the environment; multimedia lead
exposure (via air, food, water, etc.) and biokinetic modeling of contributions of such exposures
to concentrations of lead in brain, kidney, and other tissues (e.g., blood and bone concentrations,
as key indices of lead exposure).; characterization of lead health effects and associated exposure-
response relationships; and delineation of environmental (ecological) effects of lead. This final
version of the revised Lead AQCD mainly assesses pertinent literature published or accepted for
publication through December 2005.
The First External Review Draft (dated December 2005) of the revised Lead AQCD
underwent public comment and was reviewed by the Clean Air Scientific Advisory Committee
(CASAC) at a public meeting held in Durham, NC on February 28-March 1, 2006. The public
comments and CASAC recommendations received were taken into account in making
appropriate revisions and incorporating them into a Second External Review Draft (dated May,
2006) which was released for further public comment and CASAC review at a public meeting
held June 28-29, 2006. In addition, still further revised drafts of the Integrative Synthesis
chapter and the Executive Summary were then issued and discussed during an August 15, 2006
CASAC teleconference call. Public comments and CASAC advice received on these latter
materials, as well as Second External Review Draft materials, were taken into account in making
and incorporating further revisions into this final version of this Lead AQCD, which is being
issued to meet an October 1, 2006 court-ordered deadline. Evaluations contained in the present
document provide inputs to an associated Lead Staff Paper prepared by EPA's Office of Air
Quality Planning and Standards (OAQPS), which poses options for consideration by the EPA
Administrator with regard to proposal and, ultimately, promulgation of decisions on potential
retention or revision, as appropriate, of the current Pb NAAQS.
Preparation of this document has been coordinated by staff of EPA's National Center for
Environmental Assessment in Research Triangle Park (NCEA-RTP). NCEA-RTP scientific
staff, together with experts from academia, contributed to writing of document chapters. Earlier
drafts of document materials were reviewed by scientists from other EPA units and by non-EPA
experts in several public peer consultation workshops held by EPA in July/August 2005.
Il-iv
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NCEA acknowledges the valuable contributions provided by authors, contributors, and
reviewers and the diligence of its staff and contractors in the preparation of this document. The
constructive comments provided by public commenters and CASAC that served as valuable
inputs contributing to improved scientific and editorial quality of the document are also
acknowledged by NCEA.
DISCLAIMER
Mention of trade names or commercial products in this document does not constitute
endorsement or recommendation for use.
II-v
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Air Quality Criteria for Lead
(Second External Review Draft)
VOLUME I
EXECUTIVE SUMMARY E-l
1. INTRODUCTION 1-1
2. CHEMISTRY, SOURCES, AND TRANSPORT OF LEAD 2-1
3. ROUTES OF HUMAN EXPOSURE TO LEAD AND OBSERVED
ENVIRONMENTAL CONCENTRATIONS 3-1
4. TOXICOKINETICS, BIOLOGICAL MARKERS, AND MODELS OF LEAD
BURDEN IN HUMANS 4-1
5. TOXICOLOGICAL EFFECTS OF LEAD IN LABORATORY ANIMALS
AND IN VITRO TEST SYSTEMS 5-1
6. EPIDEMIOLOGIC STUDIES OF HUMAN HEALTH EFFECTS
ASSOCIATED WITH LEAD EXPOSURE 6-1
7. ENVIRONMENTAL EFFECTS OF LEAD 7-1
8. INTEGRATIVE SYNTHESIS OF LEAD EXPOSURE/HEALTH
EFFECTS INFORMATION 8-1
VOLUME II
CHAPTER 4 ANNEX (TOXICOKINETICS, BIOLOGICAL MARKERS, AND
MODELS OF LEAD BURDEN IN HUMANS) AX4-1
CHAPTER 5 ANNEX (TOXICOLOGICAL EFFECTS OF LEAD IN
LABORATORY ANIMALS AND IN VITRO TEST SYSTEMS) AX5-1
CHAPTER 6 ANNEX (EPIDEMIOLOGIC STUDIES OF HUMAN HEALTH
EFFECTS ASSOCIATED WITH LEAD EXPOSURE) AX6-1
CHAPTER 7 ANNEX (ENVIRONMENTAL EFFECTS OF LEAD) AX7-1
Il-vi
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Table of Contents
Page
PREFACE II-iii
DISCLAIMER II-v
List of Tables II-x
Authors, Contributors, and Reviewers II-xxi
U.S. Environmental Protection Agency Project Team for Development of Air
Quality Criteria for Lead II-xxvii
U.S. Environmental Protection Agency Science Advisory Board (SAB) Staff
Office Clean Air Scientific Advisory Committee (CASAC) II-xxix
Abbreviations and Acronyms II-xxxi
AX4. CHAPTER 4 ANNEX (TOXICOKINETICS, BIOLOGICAL MARKERS,
AND MODELS OF LEAD BURDEN IN HUMANS) AX4-1
REFERENCES AX4-44
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List of Tables
Page
AX4-1 Analytical Methods for Determining Lead in Blood, Urine, and Hair AX4-2
AX4-2 Summary of Selected Measurements of PbB Levels in Humans AX4-4
AX4-3 Bone Lead Measurements in Cadavers AX4-7
AX4-4 Bone Lead Measurements in Environmentally-Exposed Subjects AX4-9
AX4-5 Bone Lead Measurements in Occupationally-Exposed Subjects AX4-12
AX4-6 Bone Lead Contribution to PbB AX4-19
AX4-7 Bone Lead Studies in Pregnant and Lactating Subjects AX4-22
AX4-8 Bone Lead Studies of Menopausal and Middle-aged to Elderly Subjects AX4-30
AX4-9 Lead in Deciduous Teeth from Urban and Remote Environments AX4-36
AX4-10 Lead in Deciduous Teeth from Polluted Environments AX4-3 8
AX4-11 Summary of Selected Measurements of Urine Lead Levels in Humans AX4-39
AX4-12 Summary of Selected Measurements of Hair Lead Levels in Humans AX4-42
II-x
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Authors, Contributors, and Reviewers
CHAPTER 4 ANNEX (TOXICOKINETICS, BIOLOGICAL MARKERS, AND
MODELS OF LEAD BURDEN IN HUMANS)
Chapter Managers/Editors
Dr. James Brown—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Principal Authors
Dr. Brian Gulson—Graduate School of the Environment, Macquarie University
Sydney, NSW 2109, Australia
Contributors and Reviewers
Dr. Lester D. Grant—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. John Vandenberg—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
CHAPTER 5 ANNEX (TOXICOLOGICAL EFFECTS OF LEAD IN HUMANS
AND LABORATORY ANIMALS)
Chapter Managers/Editors
Dr. Anuradha Mudipalli—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Srikanth Nadadur—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Lori White—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Principal Authors
Dr. Anuradha Mudipalli—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (Sections 5-2, 5-10)
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Authors, Contributors, and Reviewers
(cont'd)
Principal Authors
(cont'd)
Dr. Stephen Lasley—Dept. of Biomedical and Therapeutic Sciences, Univ. of Illinois College of
Medicine, PO Box 1649, Peoria, IL 61656 (Section 5.3)
Dr. Lori White—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (Section 5.3)
Dr. Gary Diamond— Syracuse Research Corporation, 8191 Cedar Street, Akron, NY 14001
(Section 5.4)
Dr. N.D. Vaziri—Division of Nephrology and Hypertension, University of California - Irvine
Medical Center, 101, The City Drive, Bldg 53, Room #125. Orange, CA 92868 (Section 5.5)
Dr. John Pierce Wise, Sr.—Maine Center for Toxicology and Environmental Health,
Department of Applied Medical Sciences, 96 Falmouth Street, PO Box 9300, Portland, ME
04104-9300 (Section 5.6)
Dr. Harvey C. Gonick—David Geffen School of Medicine, University of California at
Los Angeles, 201 Tavistock Ave, Los Angeles, CA 90049 (Sections 5.7, 5.11)
Dr. Gene E. Watson—University of Rochester Medical Center, Box 705, Rochester, NY 14642
(Section 5.8)
Dr. Rodney Dietert—Institute for Comparative and Environmental Toxicology, College of
Veterinary Medicine, Cornell University, Ithaca, NY 14853 (Section 5.9)
Contributors and Reviewers
Dr. Lester D. Grant—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Paul Reinhart—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Michael Davis—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. David A. Lawrence—Dept of Environmental and Clinical Immunology, Empire State Plaza
P.O. Box 509, Albany, NY 12201
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Authors, Contributors, and Reviewers
(cont'd)
Contributors and Reviewers
(cont'd)
Dr. Michael J. McCabe, Jr.—Dept of Environmental Medicine, University of Rochester,
575 Elmwood Avenue, Rochester, NY 14642
Dr. Theodore I. Lidsky—New York State Institute for Basic Research, 1050 Forest RD,
Staten Island, NY 10314
Dr. Mark H. Follansbee—Syracuse Research Corporation, 8191 Cedar St. Akron, NY 14001
Dr. William K. Boyes—National Health and Environmental Effects Research Laboratory,
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Philip J. Bushnell—National Health and Environmental Effects Research Laboratory,
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Ms. Beth Hassett-Sipple—Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Dr. Zachary Pekar—Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Dr. John Vandenberg—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
CHAPTER 6 ANNEX (EPIDEMIOLOGICAL STUDIES OF AMBIENT LEAD
EXPOSURE EFFECTS)
Chapter Managers/Editors
Dr. Jee Young Kim—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Dennis Kotchmar—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. David Svendsgaard—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
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Authors, Contributors, and Reviewers
(cont'd)
Principal Authors
Dr. David Bellinger—Children's Hospital, Farley Basement, Box 127, 300 Longwood Avenue,
Boston, MA 02115 (Section 6.10)
Dr. Margit Bleecker—Center for Occupational and Environmental Neurology, 2 Hamill Road,
Suite 225, Baltimore, MD 21210 (Section 6.3)
Dr. Gary Diamond— Syracuse Research Corporation, 8191 Cedar Street.
Akron, NY 14001 (Section 6.8, 6.9)
Dr. Kim Dietrich—University of Cincinnati College of Medicine, 3223 Eden Avenue,
Kettering Laboratory, Room G31, Cincinnati, OH 45267 (Section 6.2)
Dr. Pam Factor-Litvak—Columbia University Mailman School of Public Health, 722 West
168th Street, Room 1614, New York, NY 10032 (Section 6.6)
Dr. Vic Hasselblad—Duke University Medical Center, Durham, NC 27713 (Section 6.10)
Dr. Stephen J. Rothenberg—CINVESTAV-IPN, Merida, Yucatan, Mexico & National Institute
of Public Health, Cuernavaca, Morelos, Mexico (Section 6.5)
Dr. Neal Simonsen—Louisiana State University Health Sciences Center, School of Public Health
& Stanley S Scott Cancer Center, 1600 Canal Street, Suite 800, New Orleans, LA 70112
(Section 6.7)
Dr. Kyle Steenland—Rollins School of Public Health, Emory University, 1518 Clifton Road,
Room 268, Atlanta, GA 30322 (Section 6.7)
Dr. Virginia Weaver—Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe
Street, Room 7041, Baltimore, MD 21205 (Section 6.4)
Contributors and Reviewers
Dr. J. Michael Davis—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Lester D. Grant—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Kazuhiko Ito—Nelson Institute of Environmental Medicine, New York University School of
Medicine, Tuxedo, NY 10987
II-xxiv
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Authors, Contributors, and Reviewers
(cont'd)
Contributors and Reviewers
(cont'd)
Dr. Kathryn Mahaffey—Office of Prevention, Pesticides and Toxic Substances,
U.S. Environmental Protection Agency, Washington, DC 20460
Dr. Karen Martin—Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Dr. Zachary Pekar—Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Ms. Beth Hassett-Sipple—Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Dr. John Vandenberg—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
CHAPTER 7 ANNEX (ENVIRONMENTAL EFFECTS OF LEAD)
Chapter Manager/Editor
Dr. Timothy Lewis—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Principle Authors
Dr. Ruth Hull—Cantox Environmental Inc., 1900 Minnesota Court, Suite 130, Mississauga,
Ontario, L5N 3C9 Canada (Section 7.1)
Dr. James Kaste—Department of Earth Sciences, Dartmouth College, 352 Main Street, Hanover,
NH 03755 (Section 7.1)
Dr. John Drexler—Department of Geological Sciences, University of Colorado, 1216 Gillespie
Drive, Boulder, CO 80305 (Section 7.1)
Dr. Chris Johnson—Department of Civil and Environmental Engineering, Syracuse University,
365 Link Hall, Syracuse, NY 13244 (Section 7.1)
Dr. William Stubblefield—Parametrix, Inc. 33972 Texas St. SW, Albany, OR 97321
(Section 7.2)
II-XXV
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Authors, Contributors, and Reviewers
(cont'd)
Principle Authors
(cont'd)
Dr. Dwayne Moore—Cantox Environmental, Inc., 1550ALaperriere Avenue, Suite 103,
Ottawa, Ontario, K1Z 7T2 Canada (Section 7.2)
Dr. David Mayfield—Parametrix, Inc., 411 108th Ave NE, Suite 1800, Bellevue, WA 98004
(Section 7.2)
Dr. Barbara Southworth—Menzie-Cura & Associates, Inc., 8 Winchester Place, Suite 202,
Winchester, MA 01890 (Section 7.3)
Dr. Katherine Von Stackleberg—Menzie-Cura & Associates, Inc., 8 Winchester Place, Suite
202, Winchester, MA 01890 (Section 7.3)
Contributors and Reviewers
Dr. Jerome Nriagu—Department of Environmental Health Sciences, 109 South Observatory,
University of Michigan, Ann Arbor, MI 48109
Dr. Judith Weis—Department of Biology, Rutgers University, Newark, NJ 07102
Dr. Sharon Harper—National Exposure Research Laboratory (D205-05), U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Dr. Karen Bradham—National Research Exposure Laboratory (D205-05), U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Dr. Ginger Tennant—Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Ms. Gail Lacey—Office of Air Quality Planning and Standards, U.S. Environmental Protection
Agency, Research Triangle Park, NC 27711
Dr. John Vandenberg—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
II-xxvi
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U.S. Environmental Protection Agency Project Team
for Development of Air Quality Criteria for Lead
Executive Direction
Dr. Lester D. Grant (Director)—National Center for Environmental Assessment-RTF Division,
(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Scientific Staff
Dr. Lori White (Lead Team Leader)—National Center for Environmental Assessment
(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. James S. Brown—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Robert Elias—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (Retired)
Dr. Brooke Hemming—National Center for Environmental Assessment (B243-01), U.S.
Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Jee Young Kim—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Dennis Kotchmar—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Timothy Lewis—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Anuradha Muldipalli—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Srikanth Nadadur—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Paul Reinhart—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Mary Ross— National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. David Svendsgaard—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
II-xxvii
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U.S. Environmental Protection Agency Project Team
for Development of Air Quality Criteria for Lead
(cont'd)
Technical Support Staff
Mr. Douglas B. Fennell—Technical Information Specialist, National Center for Environmental
Assessment (B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC
27711 (Retired)
Ms. Emily R. Lee—Management Analyst, National Center for Environmental Assessment
(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Ms. Diane H. Ray—Program Specialist, National Center for Environmental Assessment
(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Ms. Donna Wicker—Administrative Officer, National Center for Environmental Assessment
(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (Retired)
Mr. Richard Wilson—Clerk, National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Document Production Staff
Ms. Carolyn T. Perry—Task Order Manager, Computer Sciences Corporation, 2803 Slater Road,
Suite 220, Morrisville, NC 27560
Mr. John A. Bennett—Technical Information Specialist, Library Associates of Maryland,
11820 Parklawn Drive, Suite 400, Rockville, MD 20852
Mr. William Ellis—Records Management Technician, InfoPro, Inc., 8200 Greensboro Drive,
Suite 1450, McLean, VA 22102
Ms. Sandra L. Hughey—Technical Information Specialist, Library Associates of Maryland,
11820 Parklawn Drive, Suite 400, Rockville, MD 20852
Dr. Barbara Liljequist—Technical Editor, Computer Sciences Corporation, 2803 Slater Road,
Suite 220, Morrisville, NC 27560
Ms. Michelle Partridge-Doerr—Publications/Graphics Specialist, TEK Systems, 1201 Edwards
Mill Road, Suite 201, Raleigh, NC 27607
Mr. Carlton Witherspoon—Graphic Artist, Computer Sciences Corporation, 2803 Slater Road,
Suite 220, Morrisville, NC 27560
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U.S. Environmental Protection Agency
Science Advisory Board (SAB) Staff Office
Clean Air Scientific Advisory Committee (CASAC)
Chair
Dr. Rogene Henderson*—Scientist Emeritus, Lovelace Respiratory Research Institute,
Albuquerque, NM
Members
Dr. Joshua Cohen—Faculty, Center for the Evaluation of Value and Risk, Institute for Clinical
Research and Health Policy Studies, Tufts New England Medical Center, Boston, MA
Dr. Deborah Cory-Slechta—Director, University of Medicine and Dentistry of New Jersey and
Rutgers State University, Piscataway, NJ
Dr. Ellis Cowling*—University Distinguished Professor-at-Large, North Carolina State
University, Colleges of Natural Resources and Agriculture and Life Sciences, North Carolina
State University, Raleigh, NC
Dr. James D. Crapo [M.D.]*—Professor, Department of Medicine, National Jewish Medical and
Research Center, Denver, CO
Dr. Bruce Fowler—Assistant Director for Science, Division of Toxicology and Environmental
Medicine, Office of the Director, Agency for Toxic Substances and Disease Registry, U.S.
Centers for Disease Control and Prevention (ATSDR/CDC), Chamblee, GA
Dr. Andrew Friedland—Professor and Chair, Environmental Studies Program, Dartmouth
College, Hanover, NH
Dr. Robert Goyer [M.D.]—Emeritus Professor of Pathology, Faculty of Medicine, University of
Western Ontario (Canada), Chapel Hill, NC
Mr. Sean Hays—President, Summit Toxicology, Allenspark, CO
Dr. Bruce Lanphear [M.D.]—Sloan Professor of Children's Environmental Health, and the
Director of the Cincinnati Children's Environmental Health Center at Cincinnati Children's
Hospital Medical Center and the University of Cincinnati, Cincinnati, OH
Dr. Samuel Luoma—Senior Research Hydrologist, U.S. Geological Survey (USGS),
Menlo Park, CA
II-xxix
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U.S. Environmental Protection Agency
Science Advisory Board (SAB) Staff Office
Clean Air Scientific Advisory Committee (CASAC)
(cont'd)
Members
(cont'd)
Dr. Frederick J. Miller*—Consultant, Gary, NC
Dr. Paul Mushak—Principal, PB Associates, and Visiting Professor, Albert Einstein College of
Medicine (New York, NY), Durham, NC
Dr. Michael Newman—Professor of Marine Science, School of Marine Sciences, Virginia
Institute of Marine Science, College of William & Mary, Gloucester Point, VA
Mr. Richard L. Poirot*—Environmental Analyst, Air Pollution Control Division, Department of
Environmental Conservation, Vermont Agency of Natural Resources, Waterbury, VT
Dr. Michael Rabinowitz—Geochemist, Marine Biological Laboratory, Woods Hole, MA
Dr. Joel Schwartz—Professor, Environmental Health, Harvard University School of Public
Health, Boston, MA
Dr. Frank Speizer [M.D.]*—Edward Kass Professor of Medicine, Channing Laboratory, Harvard
Medical School, Boston, MA
Dr. Ian von Lindern—Senior Scientist, TerraGraphics Environmental Engineering, Inc.,
Moscow, ID
Dr. Barbara Zielinska*—Research Professor, Division of Atmospheric Science, Desert Research
Institute, Reno, NV
SCIENCE ADVISORY BOARD STAFF
Mr. Fred Butterfield—CASAC Designated Federal Officer, 1200 Pennsylvania Avenue, N.W.,
Washington, DC, 20460, Phone: 202-343-9994, Fax: 202-233-0643 (butterfield.fred@epa.gov)
(Physical/Courier/FedEx Address: Fred A. Butterfield, III, EPA Science Advisory Board Staff
Office (Mail Code 1400F), Woodies Building, 1025 F Street, N.W., Room 3604, Washington,
DC 20004, Telephone: 202-343-9994)
*Members of the statutory Clean Air Scientific Advisory Committee (CASAC) appointed by the
U.S. EPA Administrator
II-XXX
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Abbreviations and Acronyms
aFGF
AA
AAL
AAS
ABA
ACBP
ACE
ACh
AChE
ACR
AD
ADC
ADP
AE
AEA
AFC
2-AG
A horizon
AHR
AI
ALA
ALAD
ALAS
ALAU
ALD
ALS
ALT
ALWT
AMEM
AMP
ANCOVA
ANF
Angll
ANOVA
a-fibroblast growth factor
arachidonic acid
active avoidance learning
atomic absorption spectroscopy
p-aminoisobutyric acid
Achenbach Child Behavior Profile
angiotensin converting enzyme
acetylcholine
acetylcholinesterase
acute-chronic ratio
adult
analog digital converter
adenosine diphosphate
anion exchange
TV-arachi dony 1 ethanol amine
antibody forming cells
2-arachidonylglycerol
uppermost layer of soil (litter and humus)
aryl hydrocarbon receptor
angiotensin I
5-aminolevulinic acid
5-aminolevulinic acid dehydratase
aminolevulinic acid synthetase
urinary 5-aminolevulinic acid
aldosterone
amyotrophic lateral sclerosis
alanine aminotransferase
albumin weight
Alpha Minimal Essential Medium
adenosine monophosphate
analysis of covariance
atrial natriuretic factor
angiotensin II
analysis of variance
II-xxxi
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ANP
AP
AP-1
ApoE
AQCD
Arg
AS52
ASGP-R
AST
ASV
3-AT
ATP
ATP1A2
ATPase
ATSDR
AVCD
AVS
AWQC
P
PFGF
17P-HS
3P-HSD
17P-HSDH
6p-OH-cortisol
B
BAEP
BAER
BAF
Bcell
BCFs
BCS
BDNF
BDWT
BEI
BFU-E
atrial natriuretic peptide
alkaline phosphatase
activated protein-1
apolipoprotein E
Air Quality Criteria Document
arginine
cells derived from the CHO cell line
aceyl glycoprotein receptor
aspartate aminotransferase
anode stripping voltammetry
3-aminotriazole; 3-amino triazide
adenosine triphosphate
sodium-potassium adenosine triphosphase a2
adenosine triphosphatase
Agency for Toxic Substances and Disease Research
atrioventricular conduction deficit
acid volatile sulfide
ambient water quality criteria
beta-coefficient; slope of an equation
P-fibroblast growth factor
17p-hydroxysteriod
3p-hydroxysteriod dehydrogenase
17p-hydroxysteriod dehydrogenase
6-p-hydroxycortisol
both
brainstem auditory-evoked potentials
brainstem auditory-evoked responses
bioaccumulation factor
B lymphocyte
bioconcentration factors
bovine calf serum
brain derived neurotrophic factor
body weight changes
biological exposure index
blood erythroid progenitor
II-xxxii
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BLL
BLM
BM
BMI
BDNF
BOTMP
BP
BPb
BSA
BSI
BTQ
BUN
bw, b. wt, BW
C3H10T/12
C3, C4
CA
CAS
45Ca
Ca-ATP
Ca-ATPase
CaCO3
CaEDTA
CAL
CaM
Ca-Mg-ATPase
cAMP
CaNa2 EDTA
CANTAB
CAT
CBCL
CBCL-T
CBL
CBLI
CCB
CCD
blood lead level
biotic ligand model
basement membrane
body mass index
brain-derived neurotrophic factor
Bruinicks-Oseretsky Test of Motor Proficiency
blood pressure
blood lead concentration
bovine serum albumin
Brief Symptom Inventory
Boston Teacher Questionnaire
blood urea nitrogen
body weight
mouse embryo cell line
complement proteins
chromosome aberration
cornu ammonis 3 region of hippocampus
calcium-45 radionuclide
calcium-dependent adenosine triphosphate
calcium-dependent adenosine triphosphatase
calcium carbonate
calcium disodium ethylenediaminetetraacetic acid
calcitonin
calmodulin
calcium-magnesium-dependent adenosine triphosphatase
cyclic adenosinemonophosphate
calcium disodium ethylenediaminetetraacetic acid
Cambridge Neuropsychological Testing Automated Battery
catalase; Cognitive Abilities Test
Achenbach Child Behavior Checklist
Total Behavior Problem Score
cumulative blood lead
cumulative blood lead index
cytochalasin B
charge-coupled device
-------
CCE
CCL
CCS
Cd
109/^1
Cd
CdU
CEC
CESD, CES-D
GFAP
CFU-E
CFU-GEMM
CFU-GM
cGMP
ChAT
CHD
CHO
CI
CLE-SV
CLRTAP
CLS
CMC
CMI
CNS
COH
ConA
COR
CoTx
COX-2
CP
CPT
cr
CRAC
CREB
CRF
Coordination Center for Effects
carbon tetrachloride
cosmic calf serum
coefficient of component variance of respiratory sinus
arrhythmia
cadmium
cadmium-109 radionuclide
urinary cadmium
cation exchange capacity
Center for Epidemiologic Studies Depression (scale)
glial fibrillary acidic protein
colony forming unit blood-erythroid progenitor (cell count)
colony forming unit blood-pluripotent progenitor (cell count)
blood granulocyte/macrophage progenitor (cell count)
cyclic guanosine-3',5'-monophosphate
choline acetyltransferase
coronary heart disease
Chinese hamster ovary cell line
confidence interval
competitive ligand-exchange/stripping voltammetry
Convention on Long-Range Transboundary of Air Pollution
Cincinnati Lead Study
criterion maximum concentration
cell-mediated immunity
central nervous system
cation-osmotic hemolysis
concanavalin A
cortisol
cotreatment
cyclooxygenase-2
coproporphryn
current perception threshold
creatinine
calcium release activated calcium reflux
cyclic AMP-response element binding protein
chronic renal failure
II-xxxiv
-------
CRI
CSF
CuZn-SOD
CV
CVLT
CVR.R
CYP
CYPSall
D
DA
dbcAMP
DCV
DEAE
DET
DEYO
DPS
dfs
DG
DOT
DL
DMEM
DMEM/F12
DMFS
DMPS
DMSA
DMT
DMTU
DNA
DO
DOC
DOM
DOPAc
DPASV
dp/dt
DPPD
chronic renal insufficiency
cerebrospinal fluid
copper and zinc-dependent superoxide dismutase
conduction velocity
California Verbal Learning Test
coefficient of variation of the R-R interval
cytochrome (e.g., CYP1A, CYP-2A6, CYP3A4, CYP450)
cytochrome P450 Sal 1
D-statistic
dopamine; dopaminergic
dibutyryl cyclic adenosine-3',5'-monophosphate
distribution of conduction velocities
diethylaminoethyl (chromatography)
diffusive equilibrium thin films
death of young
decayed or filled surfaces, permanent teeth
covariate-adjusted number of caries
dentate gyrus
diffusive gradient thin films
DL-statistic
Dulbecco's Minimal Essential Medium
Dulbecco's Minimal Essential Medium/Ham's F12
decayed, missing, or filled surfaces, permanent teeth
2,3-dimercaptopropane 1-sulfonate
2,3-dimercaptosuccinic acid
Donnan membrane technique
dimethylthiourea
deoxyribonucleic acid
distraction osteogenesis
dissolved organic carbon
dissolved organic carbon
3,4-dihydroxyphenylacetic acid
differential pulse anodic stripping voltammetry
rate of left ventricular isovolumetric pressure
7V-7V-diphenyl-p-phynylene-diamine
II-XXXV
-------
DR
DSA
DTC
DTK
DTPA
DTT
dw
E
E2
EBE
EBV
EC
eCB
ECG
Eco-SSL
EDS
EDTA
EEDQ
EEG
EG
EGF
EGG
EGPN
EKG
electro
EM/CM
EMEM
eNOS
EP
EPA
Epi
EPMA
EPO
EPSC
drinking water
delayed spatial alternation
diethyl dithiocarbomate complex
delayed type hypersensitivity
diethylenetriaminepentaacetic acid
dithiothreitol
dry weight
embryonic day
estradiol
early biological effect
Epstein-Barr virus
European Community
effect concentration for 50% of test population
endocannabinoid
el ectrocardi ogram
ecological soil screening level
energy dispersive spectrometers
ethylenediaminetetraacetic acid
7V-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinone
el ectroencephal ogram
egg
epidermal growth factor
effects on eggs
egg production
electrocardiogram
electrophysiological stimulation
experimental medium-to-control medium (ratio)
Eagle's Minimal Essential Medium
endothelial nitric oxide synthase
erythrocyte protoporphyrin
U.S. Environmental Protection Agency
epinephrine
electron probe microanalysis
erythropoietin
excitatory postsynaptic currents
II-xxxvi
-------
EPT
ERG
ERL
ERM
EROD
ESCA
ESRD
EST
ESTH
ET
ETOH
EXAFS
EXANES
F
F344
FAV
FBS
FCS
FCV
FD
FEF
FEP
FERT
FEVi
FGF
FI
FIAM
FMLP
fMRI
FR
FSH
FT3
FT4
FTES
macroinvertebrates from the Ephemeroptera (mayflies),
Plecoptera (stoneflies), and Trichoptera (caddisflies) group
electroretinogram; electroretinographic
effects range - low
effects range - median
ethoxyresorufin-0-deethylase
electron spectroscopy for chemical analysis
end-stage renal disease
estradiol
eggshell thinning
endothelein; essential tremor
ethyl alcohol
extended X-ray absorption fine structure
extended X-ray absorption near edge spectroscopy
F-statistic
Fischer 344 (rat)
final acute value
fetal bovine serum
fetal calf serum
final chronic value
food
forced expiratory flow
free erythrocyte protoporphyrin
fertility
forced expiratory volume in one second
fibroblast growth factor (e.g., PFGF, aFGF)
fixed interval (operant conditioning)
free ion activity model
N-formy 1 -L-methi ony 1 -L-l eucy 1 -L-pheny 1 al anine
functional magnetic resonance imaging
fixed-ratio operant conditioning
follicle stimulating hormone
free triiodothyronine
free thyroxine
free testosterone
II-xxxvii
-------
FTII
FTPLM
FURA-2
FVC
Y-GT
G
GABA
GAG
G12 CHV79
GCI
GD
GDP
GEE
GFAAS
GFR
GGT
GH
GI
GIME-VIP
GIS
GLU
GMAV
GMCV
GMP
GMPH
GnRH
GOT
GP
G6PD, G6PDH
GPEI
gp91phox
GPT
GPx
GRO
Fagan Test of Infant Intelligence
flow-through permeation liquid membranes
l-[6-amino-2-(5-carboxy-2-oxazolyl)-5-benzofuranyloxy]-2-
(2-amino-5-methylphenoxy) ethane-7V,7V,jV',jV'-tetraacetic acid
forced vital capacity
y-glutamyl transferase
gestational day
gamma aminobutyric acid
glycosaminoglycan
cells derived from the V79 cell line
General Cognitive Index
gestational day
guanosine diphosphate
generalized estimating equations
graphite furnace atomic absorption spectroscopy
glomerular filtration rate
y-glutamyl transf erase
growth hormone
gastrointestinal
gel integrated microelectrodes combined with voltammetric
in situ profiling
geographic information system
glutamate
genus mean acute value
genus mean chronic value
guanosine monophosphate
general morphology
gonadotropin releasing hormone
aspartate aminotransferase
gross productivity
glucose-6-phosphate dehydrogenase
glutathione S-transferase P enhancer element
NAD(P)H oxidase
glutamic-pyruvic transaminase
glutathione peroxidase
growth
II-xxxviii
-------
GRP78
GSD
GSH
GSIM
GSSG
GST
GSTP
GTP
GV
H+
3H
HA
Hb
HBEF
HBSS
HCG; hCG
Hct
HDL
HEP
HET
HFPLM
Hgb
HGF
HH
H-H
HHANES
H-L
HLA
H-MEM
HMP
HNO3
H2O2
HOME
HOSTE
HPLC
glucose-regulated protein 78
geometric standard deviation
reduced glutathione
gill surface interaction model
glutathione disulfide
glutathione-S-transferase
placental glutathione transferase
guanosine triphosphate
gavage
acidity
hydrogen-3 radionuclide (tritium)
humic acid; hydroxyapatite
hemoglobin
Hubbard Brook Experimenatl Forest
Hank's Balanced Salt Solution
human chorionic gonadotropin
hematocrit
high-density lipoprotein (cholesterol)
habitat evaluation procedure
Binghamton heterogeneous stock
hollow fiber permeation liquid membranes
hemoglobin
hepatocyte growth factor
hydroxylamine hydrochloride
high-high
Hispanic Health and Nutrition Examination Survey
high-low
human leukocyte antigen
minimum essential medium/nutrient mixture-F12-Ham
hexose monophosphate shunt pathway
nitric acid
hydrogen peroxide
Home Observation for Measurement of Environment
human osteosarcoma cells
high-pressure liquid chromatography
II-xxxix
-------
H3PO4
HPRT
HR
HSI
H2SO4
HSPG
Ht
HTC
hTERT
HTN
IBL
IBL x WRAT-R
ICD
ICP
ICP-AES
ICP-MS, ICPMS
ID-MS
IFN
Ig
IGF-1
IL
ILL
immuno
IMP
iNOS
i.p., IP
IPSC
IQ
IRT
ISEL
ISI
i.v., IV
IVCD
JV
phosphoric acid
hypoxanthine phosphoribosyltransferase (gene)
heart rate
habitat suitability indices
sulfuric acid
heparan sulfate proteoglycan
hematocrit
hepatoma cells
catalytic subunit of human telomerase
hypertension
integrated blood lead index
integrated blood lead index x Wide Range Achievement
Test-Revised (interaction)
International Classification of Diseases
inductively coupled plasma
inductively coupled plasma atomic emission spectroscopy
inductively coupled plasma mass spectrometry
isotope dilution mass spectrometry
interferon (e.g., IFN-y)
immunoglobulin (e.g., IgA, IgE, IgG, IgM)
insulin-like growth factor 1
interleukin (e.g., IL-1, IL-lp, IL-4, IL-6, IL-12)
incipient lethal level
immunohistochemical staining
inosine monophosphate
inducible nitric oxide synthase
intraperitoneal
inhibitory postsynaptic currents
intelligence quotient
interresponse time
in situ end labeling
interstimulus interval
intravenous
intraventricular conduction deficit
juvenile
II-xl
-------
KABC
KTEA
KXRF, K-XRF
LA
LB
LC
LD50
LDH
LDL
L-dopa
LE
LET
LH
LHRH
LN
L-NAME
LOAEL
LOEC
LOWES S
LPO
LPP
LPS
LT
LT50
LTER
LTP
LVH
liPIXE
liSXRF
MA
MA- 10
MANCOVA
MAO
Kaufman Assessment Battery for Children
Kaufman Test of Educational Achievement
K-shell X-ray fluorescence
lipoic acid
laying bird
lactation
lethal concentration at which 50% of exposed animals die
lethal concentration at which 74% of exposed animals die
lethal dose at which 50% of exposed animals die
lactate dehydrogenase
low-density lipoprotein (cholesterol)
3,4-dihydroxyphenylalanine (precursor of dopamine)
Long Evans (rat)
linear energy transfer (radiation)
luteinizing hormone
luteinizing hormone releasing hormone
lead nitrate
L-7V°-nitroarginine methyl ester
lowest-observed adverse effect level
lowest-observed-effect concentration
locally weighted scatter plot smoother
lipoperoxide
lipid peroxidation potential
lipopolysaccharide
leukotriene
time to kill 50%
Long-Term Ecological Research (sites)
long term potentiation
left ventricular hypertrophy
microfocused particle induced X-ray emission
microfocused synchrotron-based X-ray fluorescence
mature
mouse Ley dig tumor cell line
multivariate analysis of covariance
monoamine oxidase
-------
MATC
MDA
MDA-TBA
MDCK
MDI
MDRD
MEM
MG
Mg-ATPase
MiADMSA
Mi-DMSA
MK-801
MLR
MMSE
MMTV
MN
MND
MNNG
MPH
MRI
mRNA
MROD
MRS
MS
MSCA
mSQGQs
MT
MVV
MW
N, n
N/A
NAAQS
NAC
NAD
NADH
maximum acceptable threshold concentration
malondialdehyde
malondialdehyde-thiobarbituric acid
kidney epithelial cell line
Mental Development Index (score)
Modification of Diet in Renal Disease (study)
Minimal Essential Medium
microglobulin
magnesium-dependent adenosine triphosphatase
monoisamyl dimercaptosuccinic acid
mi monoisoamyl dimercaptosuccinic acid
NMD A receptor antagonist
mixed lymphocyte response
Mini-Mental State Examination
murine mammary tumor virus
micronuclei formation
motor neuron disease
7V-methyl-jV'-nitro-7V-nitrosoguanidine
morphology
magnetic resonance imaging
messenger ribonucleic acid
methoxyresorufm-O-demethylase
magnetic resonance spectroscopy
mass spectrometry
McCarthy Scales of Children's Abiltities
mean sediment quality guideline quotients
metallothionein
maximum voluntary ventilation
molecular weight (e.g., high-MW, low-MW)
number of observations
not available
National Ambient Air Quality Standards
TV-acetyl cysteine
nicotinamide adenine dinucleotide
reduced nicotinamide adenine dinucleotide
-------
NADP
NAD(P)H, NADPH
NADS
NAF
NAG
Na-K-ATPase
NAWQA
NET
NCBP
NCD
NCS
NCTB
NCV
ND
NDI
NE
NES
NF-KB
NGF
NHANES
NIOSH
NIST
NK
NMDA
NMDAR
NMR
NO
NO2
NO3
NOAEC
NOAEL
NOEC
NOEL
NOM
NORs
nicotinamide adenine dinucleotide phosphate
reduced nicotinamide adenine dinucleotide phosphate
nicotinamide adenine dinucleotide synthase
nafenopin
7V-acetyl-p-D-glucosaminidase
sodium-potassium-dependent adenosine triphosphatase
National Water-Quality Assessment
nitro blue tetrazolium
National Contaminant Biomonitoring Program
nuclear chromatin decondensation (rate)
newborn calf serum
Neurobehavioral Core Test Battery
nerve conduction velocity
non-detectable; not detected
nuclear divison index
norepinephrine
Neurobehavioral Evaluation System
nuclear transcription factor-KB
nerve growth factor
National Health and Nutrition Examination Survey
National Institute for Occupational Safety and Health
National Institute for Standards and Technology
natural killer
7V-methyl-D-aspartate
7V-methyl-D-aspartate receptor
nuclear magnetic resonance
nitric oxide
nitrogen dioxide
nitrate
no-observed-adverse-effect concentration
no-observed-adverse-effect level
no-observed-effect concentration
no-observed-effect level
natural organic matter
nucleolar organizing regions
-------
NOS
NOX
NP
NPSH
NR
NRC
NRK
NS
NSAID
NT
NTA
02
ODVP
OH
7-OH-coumarin
1,25-(OH)2-D, 1,25-(OH)2D3
24,25-(OH)2-D3
25-OH-D3
8-OHdG
O horizon
OR
OSWER
P,P
P300
P450 1A1
P450 1A2
P450CYP3all
PAD
PAH
PAI-1
PAR
Pb
204pb 206pb 207pb
21
°Pb
nitric oxide synthase; not otherwise specified
nitrogen oxides
net productivity
nonprotein sulfhydryl
not reported
National Research Council
normal rat kidney
nonsignificant
non-steroidal anti-inflammatory agent
neurotrophin
nitrilotriacetic acid
oxygen
offspring development
hydroxyl
7-hydroxy-coumarin
1,25-dihydroxyvitamin D
24,25-dihydroxyvitamin D
25-hydroxyvitamin D
8-hydroxy-2'-deoxyguanosine
forest floor
odds ratio; other oral
Office of Solid Waste and Emergency Response
probability value
event-related potential
cytochrome P450 1A1
cytochrome P450 1A2
cytochrome P450 Sal 1
peripheral arterial disease
polycyclic aromatic hydrocarbon
plasminogen activator inhibitor-1
population attributable risk
lead
lead-203 radionuclide
stable isotopes of lead-204, -206, -207, -208, respectively
lead-210 radionuclide
-------
Pb(Ac)2
PbB
PbCl2
Pb(C104)2
PBG-S
PBMC
Pb(NO3)2
PbO
PBP
PbS
PbU
PC12
PCR
PCV
PDE
PDGF
PDI
PEC
PEF
PG
PHA
Pi
PIXE
PKC
plNEpi
PMA
PMN
PMR
PN
P5N
PND
p.o.,PO
POMS
ppb
ppm
lead acetate
blood lead concentration
lead chloride
lead chlorate
porphobilinogen synthase
peripheral blood mononuclear cells
lead nitrate
lead oxides (or litharge)
progressive bulbar paresis
galena
urinary lead
pheochromocytoma cell
polymerase chain reaction
packed cell volume
phosphodiesterase
platelet-derived growth factor
Psychomotor Development Index
probable effect concentration
expiratory peak flow
prostaglandin (e.g., PGE2, PGF2); prostate gland
phytohemagglutinin A
inorganic phosphate
particle induced X-ray emission
protein kinase C
plasma norepinephrine
progressive muscular atrophy
polymorphonuclear leucocyte
proportionate mortality ratio
postnatal (day)
pyrimidine 5'-nucleotidase
postnatal day
per os (oral administration)
Profile of Mood States
parts per billion
parts per million
II-xlv
-------
PPVT-R
PRA
PRL
PROG
PRR
PRWT
PST
PTH
PTHrP
PVC
PWM
PRWT
QA/QC
Q/V
r
R2
r2
226Ra
R/ALAD
RAVLT
86Rb
RBA
RBC
RBF
RBP
RBPH
RCPM
REL
REP
RHIS
222Rn
RNA
ROS
ROS 17.2.8
RPMI 1640
Peabody Picture Vocabulary Test-Revised
plasma renin activity
prolactin
progeny counts or numbers
prevalence rate ratio
progeny weight
percent transferrin saturation
parathyroid hormone
parathyroid hormone-related protein
polyvinyl chloride
pokeweed mitogen
progeny weight
quality assurance/quality control
flux of air (Q) divided by volume of culture (V)
Pearson correlation coefficient
multiple correlation coefficient
correlation coefficient
most stable isotope of radium
ratio of ALAD activity before and after reactivation
Rey Auditory Verbal Learning Test
rubidium-86 radionuclide
relative bioavailablity
red blood cell; erythrocyte
renal blood flow
retinol binding protein
reproductive behavior
Ravens Colored Progressive Matrices
rat epithelial (cells)
reproduction
reproductive organ histology
most stable isotope of radon
ribonucleic acid
reactive oxygen species
rat osteosarcoma cell line
Roswell Park Memorial Institute basic cell culture medium
-------
RR relative risk; rate ratio
RT reaction time
RSEM resorbed embryos
RSUC reproductive success (general)
RT reproductive tissue
ESEM sum of the molar concentrations of simultaneously extracted
metal
SA7 simian adenovirus
SAB Science Advisory Board
SAM ^-adenosyl-L-methionine
SBIS-4 Stanford-Binet Intelligence Scale-4th edition
s.c., SC subcutaneous
SCAN Test for Auditory Processing Disorders
SCE selective chemical extraction; sister chromatid exchange
SCP stripping chronopotentiometry
SD Spraque-Dawley (rat); standard deviation
SDH succinic acid dehydrogenase
SDS sodium dodecyl sulfate; Symbol Digit Substitution
SE standard error; standard estimation
SEM standard error of the mean
SES socioeconomic status
sGC soluble guanylate cyclase
SH sulfhydryl
SHBG sex hormone binding globulin
SHE Syrian hamster embryo cell line
SIMS secondary ion mass spectrometry
SIR standardized incidence ratio
SLP synthetic leaching procedure
SM sexually mature
SMAV species mean acute value
SMR standardized mortality ratio
SNAP Schneider Neonatal Assessment for Primates
SNP sodium nitroprusside
SC>2 sulfur dioxide
SOD superoxide dismutase
-------
SOPR
SPCL
SPCV
SQGs
SRA
SRD
SRIF
SRM
SRT
SSADMF
SSB
SSEP
StAR
STORE!
SVC
SVRT
T
TA
TABL
T&E
TAT
TB
TEARS
TBPS
TCDD
Tcell
TCLP
TE
TEC
TEDG
TEL
TES
TEWT
TF
TG
sperm-oocyte penetration rate
sperm cell counts
sperm cell viability
sediment quality guidelines
Self Reported Antisocial Behavior scale
Self Report of Delinquent Behavior
somatostatin
Standard Reference Material
simple reaction time
Social Security Administration Death Master File
single-strand breaks
somatosensory-evoked potential
steroidogenic acute regulatory protein
STOrage and RETrieval
sensory conduction velocity
simple visual reaction time
testosterone
tail
time-averaged blood lead
threatened and endangered (species)
tyrosine aminotransferase
tibia
thiobarbituric acid-reactive species
Total Behavior Problem Score
methionine-choline-deficient diet
T lymphocyte
toxic characteristic leaching procedure
testes
threshold effect concentration
testes degeneration
tetraethyl lead
testosterone
testes weight
transferrin, translocation factor
6-thioguanine
-------
TGF
TH
232^
TLC
TNF
TOP
tPA
TPRD
TRH
TRY
TSH
TSP
TT3
TT4
TIES
TTR
TU
TWA
TX
U
235U, 238U
UCP
UDP
UNECE
Ur
USFWS
USGS
UV
V79
VA
vc
VDR
VE
VEP
VI
transforming growth factor
tyrosine hydroxylase
stable isotope of thorium-232
Treatment of Lead-exposed Children (study)
tumor necrosis factor (e.g., TNF-a)
time-of-flight
plasminogen activator
total production
thyroid releasing hormone
toxicity reference value
thyroid stimulating hormone
triple-super phosphate
total triiodothyronine
serum total thyroxine
total testosterone
transthyretin
toxic unit
time-weighted average
tromboxane (e.g., TXB2)
uriniary
uranium-234 and -238 radionuclides
urinary coproporphyrin
uridine diphosphate
United Nations Economic Commission for Europe
urinary
U.S. Fish and Wildlife Service
United States Geological Survey
ultraviolet
Chinese hamster lung cell line
Veterans Administration
vital capacity; vitamin C
vitamin D receptor
vitamin E
visual-evoked potential
variable-interval
-------
vitC
vitE
VMA
VMI
VSM
VSMC
WAIS
WDS
WHO
wise
WISC-R
WO
WRAT-R
WT
WTHBF-6
ww
XAFS
XANES
XAS
XPS
X-rays
XRD
XRF
ZAP
ZnNa2 DTPA
ZnNa2 EDTA
ZPP
vitamin C
vitamin E
vanilmandelic acid
Visual-Motor Integration
vascular smooth muscle (cells)
vascular smooth muscle cells
Wechsler Adult Intelligence Scale
wavelength dispersive spectrometers
World Health Organization
Wechsler Intelligence Scale for Children
Wechsler Intelligence Scale for Children-Revised
whole organism
Wide Range Achievement Test-Revised
wild type
human liver cell line
wet weight
X-ray absorption fine structure
X-ray absorption near edge spectroscopy
X-ray absorption spectroscopy
X-ray photoelectron spectroscopy
synchrotron radiation
X-ray diffraction
X-ray fluorescence
correction in reference to three components of matrix effects:
atomic number (Z), absorption (A), and fluorescence (F)
zinc disodium diethylenetriaminepentaacetic acid
zinc disodium ethylenediaminetetraacetic acid
zinc protoporphyrin
II-l
-------
AX4. CHAPTER 4 ANNEX
ANNEX TABLES AX4
AX4-1
-------
Table AX4-1. Analytical Methods for Determining Lead in Blood, Urine, and Hair
to
Sample
Matrix
Blood
Blood
Blood
Blood
Blood
Blood
Blood and
urine
Blood and
urine
Blood and
urine
Blood and
tissue
Preparation Method
Wet ashing with acid mixtures; residue dissolution in
dilute HC1O4
Wet ashing with HNO3; residue dissolution in dilute
HNO3
Dilution with Triton X-100®; addition of nitric acid
and diammonium phosphate
Dilution of sample with ammonium solution
containing Triton X-100
Dilution of sample in 0.2% Triton X-100 and water
Wet ashing, dilution
Mixing of urine sample with HNO3; filtration,
chelation of lead in whole blood or filtered urine with
APDC, extraction with MTBK
Wet ashing of sample with HNO3, complexation
with diphenylthio-carbazone, and extraction with
chloroform
206Pb addition and sample acid digestion; lead
coprecipitation by addition of Ba(NO3)2, followed by
electrodeposition on platinum wire
Digestion of sample with HNO3/HC1O4 /H2SO4; heat
Analytical Method
ASV with mercury-
graphite electrode
(NIOSH Method 195)
GFAAS
(NIOSH Method 214)
GFAAS
ICP/MS
GFAAS
ICP-MS
GFAAS
AAS
(NIOSH Method 8003)
Spectrophotometry
(NIOSH Method 102)
IDMS
ICP-AES (Method 8005)
Sample
Detection Limit
40ng/L
100 ng/L
2.4 ng/L
15ng/L
«15ng/L
0.1 ppb
4ppb
0.05 ng/g (blood);
50 ng/L (urine)
30 ng/L (blood);
12 ng/L (urine)
No data
0.01 ng/g (blood);
0.2 jig/g (tissue)
Accuracy
(percent recovery)
95-105
No data
93-105
96-111
97-150
94-100
90-108
99 (±10.8%)
97
97
98-99
113
Reference
NIOSH (1977b)
NIOSH (1977e)
Aguilera de Benzo
etal. (1989)
Delves and Campbell
(1988)
QueHee etal. (1985)
Zhang etal. (1997)
NIOSH (1994)
NIOSH (1977a)
Manton and Cook
(1984)
NIOSH (1984)
-------
Table AX4-1 (cont'd). Analytical Methods for Determining Lead in Blood, Urine, and Hair
Sample
Matrix
Blood
Urine
Preparation Method
Addition of 50 uL of blood into reagent, mixing,
and transferring to sensor strip (commercial test kit)
Collect 50 mL urine sample and add 5 mL
Analytical Method
Gold electrode sensor
ICP-AES (Method 83 10)
Sample
Detection Limit
1.4ng/dL
5 ug/L
Accuracy
(percent recovery)
No data
100
Reference
ESA(1998)
NIOSH(1994)
concentrated HNO3 as preservative; filter samples
through cellulose membrane, adjust pH to 8, ash filters
and resins in low temperature oxygen plasma for
6 hours
Serum, Filtration of sample if needed; blood requires
blood, and digestion in a Parr bomb; dilution of serum or urine
urine with acid or water
j> Urine Wet ashing of sample with acid mixture and
X dissolution in dilute HC1O4
Hair Cleaning of sample with acetone/ methanol; digestion
with acid mixture and heat; diammonium phosphate
addition as matrix modifier
Hair Cleaning with lauryl sulfate and water; digestion with
heated nitric acid
Hair Cleaning with water; digestion with heated nitric acid
and H2O2
Hair Cleaning with acetone/water
ICP-AES
ASV with mercury-
graphite electrode
(Method 200)
GFAAS
ICP-AES
ET-AAS
XRF
10-50 ug/L
4 ug/L
0.16 ug/g
O.026 ug/g
0.5 ug/g
85 (serum) >80
(urine, blood)
90-110
99
No data
>90
No data
Que Hee and Boyle
(1988)
NIOSH(1977c)
Wilhelmetal. (1989)
DiPietro et al. (1989)
Drashetal. (1997)
Gerhardsson et al.
(1995a)
AAS, atomic absorption spectroscopy; APDC, ammonium pyrrolidine dithiocarbamate; ASV, anode stripping voltammetry; Ba(NO3)2, barium nitrate; ET-AAS, electro-thermal
atomic absorption spectrometry; GFAAS, graphite furnace atomic absorption spectroscopy; H2O2, hydrogen peroxide; H2SO4, sulfuric acid; HC1O4, perchloric acid; HNO3,
nitric acid; ICP-AES, inductively coupled plasma/atomic emission spectroscopy; ICP-MS, inductively coupled plasma-mass spectrometry; IDMS, isotope dilution mass
spectrometry; MIBK, methyl isobutyl ketone; NIOSH, National Institute for Occupational Safety and Health; 206Pb, lead 206; XRF, X-ray fluorescence.
-------
Table AX4-2. Summary of Selected Measurements of PbB Levels in Humans
>
-k
Reference, Study
Location, and Period
United States
CDC (2005)
U.S.
1999-2002
Brodyetal. (1994)
Pirckleetal. (1998)
U.S.
1988-1994
Study Description
Design: National survey (NHANES IV)
stratified, multistage probability cluster design
Subjects: Children and adults (> 1 yrs, n = 16, 915)
in general population
Biomarker measured: PbB
Analysis: ICP-MS
Design: National survey (NHANES III)
stratified multistage probability cluster design.
Subjects: Children and adults (> 1 yrs, n = 29, 843)
in general population
Biomarker measured: PbB
Analysis: GFAAS
PbB Measurement Comment
Units: ng/dL
Geometric mean (95% CI)
Age(yr) 1999-2000
1-5: 1.66(1.60,1.72)
n: 7, 970
6-11: 1.51(1.36,1.66)
n: 905
12-19: 1.10(1.04,1.17)
n: 2, 135
>20: 1.75(1.68,1.81)
n: 4, 207
Males: 2.01(1.93,2.09)
n: 3,913
Females: 1.37(1.32,1.43)
n: 4,057
Units: |ig/dL
Geometric mean (95% CI)
Age (yr) 1988-1991
1-5: 3.6(3.3,4.0)
n: 2, 234
6-11: 2.5(2.2,2.7)
n: 1,587
12-19: 1.6(1.4,1.9)
n: 1,376
20-49: 2.6(2.5,2.8)
n: 4, 320
50-69 4.0(3.8,4.2)
n: 2,071
>70 4.0(3.7,4.3)
n: 1,613
Males: 3.7(3.5,3.9)
n: 6,051
Females: 2.1(2.0,2.2)
n: 6,068
Data from NHANES IV Phase 1
(1999-2000) and 2 (2001-2002).
2001-2002
1.45(1.39,1.40)
8,945
1.25(1.14,1.36)
1,044
0.94(0.90,0.99)
2,231
1.56(1.49,1.62)
4,772
1.78(1.71,1.86)
4,339
1.19(1.14,1.25)
4,606
Comparison of data from NHANES III
Phase 1 (1988-1991) and Phase 2
1991-1994 (1991-1994) indicated declining PbB
. _ ,. . _ _. concentrations in children.
2,392
1.9(1.8,2.1)
1,345
1.5(1.4,1.7)
1,615
2.1 (2.0,2.2)
4,716
3.1 (2.9,3.2)
2,026
3.4(3.3,3.6)
1,548
2.8(2.6,2.9)
6,258
1.9(1.8,2.)
7,384
-------
Table AX4-2 (cont'd). Summary of Selected Measurements of PbB Levels in Humans
Reference, Study
Location, and Period
Study Description
PbB Measurement
Comment
United States (cont'd)
Nash et al. (2003)
U.S.
1988-1994
Pirkle et al. (1994)
U.S.
1 976-1 980
Symanski and Hertz -
Picciotto(1995)
U.S.
1982-1984
Design: National survey (NHANES III) stratified,
multistage probability cluster design
Subjects: Women(n = 2, 575), age range:
40-59 yrs, in general population
Biomarker measured: PbB
Analysis: GFAAS
Design: National survey (NHANES II, III)
stratified, multistage probability cluster design
Subjects: Children and adults (> 1 yrs, n = 29, 843)
in general population
Biomarker measured: PbB
Analysis: GFAAS
Design: National survey (HHANES) multistage-
area probability sample
Subjects: Adults, females (n = 3, 137), age range
20-60 yrs, in general Hispanic population
Biomarker measured: PbB
Analysis: GFAAS
Units: ug/dL
Geometric mean (95% CI, n)
Premenopausal: 1.9(1.7,2.0,1,222)
Surgically menopausal: 2.7 (2.4, 3.2, 139)
Naturally menopausal: 2.9(2.5,3.2,653)
Units: ug/dL
Geometric mean (95% CI)
Age (yr)
1-5:
n:
6-19:
n:
20-74:
n:
Males:
n:
Females:
n:
1976-1980
15
.0(14.2,
15,
.8)
2,271
11
.7(11.2,
12.4)
2,024
13
5,
15
4,
11
4,
.1 (12.7,
537
.0(14.5,
895
.1(10.6,
937
13,
15,
11
•7)
•5)
•5)
1988-1991
3
2
1
2
3
6
3
6
2
6
.6(3.
,234
.9(1.
,963
.0(2.
,922
.7(3.
,051
.1(2.
,068
3,4.0)
7,2.2)
8, 3.2)
5,3.9)
0,2.2)
Units: ug/dL
Arithmetic mean (SE, n)
All
Premenopausal: 7.5 (0.07, 1, 984)
Menopausal: 8.9 (0.11, 1, 152)
Mexican-American:
Premenopausal: 7.2(0.13,1,219)
Menopausal: 8.4 (0.20, 624)
Geometric mean PbB concentrations
were significantly lower in
premenopausal women. Increasing
PbB concentrations were significantly
associated with decreased bone mineral
density.
Comparison of data from NHANES II
(1976-1980) and Phase 1 of NHANES
III (1988-1991) indicated declining
PbB concentrations in U.S. population.
Mean difference between
premenopausal and postmenopausal
(<4 yrs) was 1.4 ug/dL
(95% CI: 0.20,2.7).
-------
Table AX4-2 (cont'd). Summary of Selected Measurements of PbB Levels in Humans
Reference, Study
Location, and Period Study Description PbB Measurement
United States (cont'd)
Yassin et al. (2004) Design: National survey (NHANES III) stratified, Units: ug/dL
U.S. multistage probability cluster design Occupation
1 988-1 994 Subjects: Adults (n = 1 1 , 126) in general ,
population, age range: 1 8-64 yr), stratified by Vehlcle mechanlcs
occupational category Food service workers
Biomarker measured: PbB Management, professional
Analysis: GFAAS technical, and sales workers
Personal service workers
Agricultural workers
Production workers: machine
operators, material movers, etc.
Laborers other than in construction
Transportation workers
Mechanics other than vehicle
mechanics
Construction trades people
Construction laborers
Health service workers
All
Comments
GM
4.80
2.00
2.13
2.48
2.76
2.88
3.47
3.49
3.50
3.66
4.44
1.76
2.42
GSD
3.88
2.69
4.05
4.52
4.02
4.24
3.36
5.19
4.91
4.64
7.84
2.24
6.93
Maximum
28.1
27.0
39.4
25.9
23.4
52.9
21.8
22.3
16.6
16.9
36.0
22.4
52.9
n
169
700
4,768
1,130
498
1,876
137
530
227
470
122
499
11,126
Mexico
Hernandez-A vila et al.
(2002)
Mexico
1993-1995
Design: Cross-sectional
Subjects: Adults females (n = 903) in general
population, age range: 36-70 yr
Biomarker measured: PbB
Analysis: GFAAS
Units: ng/dL
Arithmetic mean (SD, n)
Premenopausal: 10.63 (5.46, 463)
Menopausal: 11.39 (2.65, 437)
Surgically menopausal: 10.23 (4.92, 115)
Naturally menopausal: 11.30 (5.88, 322)
Mean difference between
premenopausal and menopausal; was
0.76 ug/dL (95% CI: 0.224, 1.48).
PbB, blood lead; GFAAS, graphite furnace atomic absorption spectroscopy; ICP-MS, inductively coupled plasma-mass spectrometry; NR, not reported.
-------
Table AX4-3. Bone Lead Measurements in Cadavers
Reference, Study
Location, and Period
Study Description
Lead Measurement
Findings, Interpretation
United States
Wittmersetal. (1988)
Minnesota
1976-82
Lead in tibia, skull, iliac crest, rib,
and vertebrae. 81 Caucasian males
and 53 male cadavers ranging in age
from 0 to 98 yr. Ashing, nitric acid,
AAS.
Saltzman et al. (1990)
Cincinnati, OH
1970-71
29 tissues from 55 cadavers, mean
age 50 yrs. Muffle furnace ashing.
Pb concentrations by dithazone
method.
Mean and SEM (ng/g bone ash) >75 yr: Tibia 29.0 +3.4 (n = 28), ilium
17.0 + 2.6 (n = 29), rib 20.5 + 2.4 (n = 31), vertebra 18.8 + 2.6 (n = 30),
skull 26.1 + 3.2 (n = 28)
51-75 yr: Tibia 24.2 + 2.3 (n = 38), ilium 19.2 + 2.4 (n = 15), rib 22.3 + 2.6
(n = 40), vertebra 22.4 + 2.6 (n = 41), skull 22.8 + 2.9 (n = 29)
36-50 yr: Tibia 16.6+4.1 (n= 14), ilium 9.9 + 1.6 (n= 15), rib 9.7 + 1.7
(n = 15), vertebra 11.9 + 2.1 (n = 15), skull 15.2 + 3.3 (n = 15)
21-35 yr: Tibia 5.9+1.2 (n= 18), ilium 5.3 + 1.2 (n= 16), rib 5.0 + 1.2
(n = 18), vertebra 6.3 + 1.3 (n = 17), skull 4.9 + 1.1 (n = 17)
14-20yr: Tibia 2.3+1.0 (n= 13), ilium 2.3 + 0.9 (n= 13), rib 2.9 + 1.4
(n = 12), vertebra 3.8 + 1.4 (n = 12), skull 3.2 + 1.7 (n = 10)
0-2 yr: Tibia 0.3+0.2 (n= 11), ilium 0.0 + 0.0 (n= 11), rib 0.7 +0.4
(n = 12), vertebra 0.6 + 0.6 (n = 12), skull 0.6 + 0.4 (n = 12)
Higher concentrations of Pb in tibia compared with rib and vertebrae and
higher values for males compared with females. Males (n = 46): Ribs
6.70 + 3.96 (ng/g, wet weight), tibia 12.55 + 10.65, vertebrae 4.12 + 2.49.
Females (n = 8): Ribs 3.17 + 0.91 (jig/g, wet weight), tibia 4.54 + 2.04,
vertebrae 2.01+0.72.
Ratio of lead in tibia and
skull/iliac/rib/vertebrae
<\ from age 0 to 35 yrs then
>1 from 36 to 75 yrs and
greater than 75 yrs. Evidence
of differential distribution
amongst bones with age; the
earliest difference is apparent
during adolescence when
trabecular bone of the
vertebral body accumulates
significantly more lead than
that of the other 4 sites.
Bone Pb increased with age.
Results were similar to those
of Barry (1978) and Wittmers
etal. (1988).
Canada
Samuels etal. (1989)
Canada
1965-69
Ashed vertebral bones from male
and female cadavers from three
Canadian cities. AAS method.
Changes for different age ranges in Pb concentration for the period
1965-1969:
0-11 months: 3.98 ng/g (n = 28)
1-4 yrs: 10.02 jig/g (n = 32)
5-11 yrs: 12.91 jig/g(n = 26)
12-19 yrs: 7.11 jig/g(n = 26)
>20 yrs: 14.77 jig/g (n = 25)
For period 1965 to 1969
levels vary over age groups
(p = 0.0001) but there was
little gender difference. For
the period 1980 to 1998 for
Winnipeg, values were
approximately half to one
third those prevailing earlier.
-------
Table AX4-3 (cont'd). Bone Lead Measurements in Cadavers
Reference, Study
Location, and Period
Study Description
Lead Measurement
Findings, Interpretation
Europe
Draschetal. (1987)
Germany
1983-85
Bone Pb in temporal
bone, cortical part of
the mid-femur, and
pelvic bone from
120 female and 120
male adult cadavers.
AAS.
Geometric means: Found cortical lead >
Males: Pelvic 1.95 + 1.00 (ng/g, wet weight), mid-femur 4.75 + 2.53, temporal 6.24 + 3.17. trabecular lead. Limited
Females: Pelvic 1.41 + 0.74 (ng/g), mid-femur 3.14 + 1.89, temporal 5.00 + 2.66. difference in Pb for younger
males and females; much
higher Pb in bones of men
>50 yr old compared with
women
-------
Table AX4-4. Bone Lead Measurements in Environmentally-Exposed Subjects
Reference, Study
Location, and Period
Study Description
Lead Measurement (SD or range)
PbB in u,g/dL, Bone Pb in u,g/g Bone Mineral
Findings, Interpretation
United States
Kim etal. (1996)
Boston, MA
1989-90
vo
Huetal. (1990)
Boston, MA
Unknown
Hu etal. (1996)
Boston, MA
1991+
Campbell et al. (2004)
New York
Unknown
Examination of the relationship between
tooth Pb in children and bone Pb levels
in young adults. Members of a cohort of
young adults (n = 63, —20 yr of age) were
reassessed 13 yr after initial examination.
Dentine Pb by anodic stripping voltammetry.
Bone K-shell XRF. LOWESS smoothing,
multiple linear regression.
To evaluate if K-shell XRF can be used to
assess low-level Pb burdens in 34 employees
(26 males, 8 females) ranging in age from 21
to 58 yr of a biomedical company with no
known history of excessive Pb exposure.
Medical environmental history
questionnaire. Multiple linear regression.
Normative Aging Study.
Subjects were middle-aged and elderly men
who had community (nonoccupational)
exposures to lead.
Cross-sectional. Backwards elimination
multivariate regression models that
considered age, race, education, retirement
status, measures of both current and
cumulative smoking, and alcohol
consumption.
Investigated the relationship between bone
mineral density_and environmental Pb
exposure in 35 African American children.
No PbB.
Tibia Pb 1.3 (+ 4.4), patella Pb 5.4 (+8.4).
Dentine Pb 13.4 (+10.7).
Approximately one-third of tibia and one-fourth
of patella estimates were negative values.
18(53%) of subjects had bone Pb levels included
0 or less within the estimate of uncertainty.
Highest bone Pb 21 + 4 ug/g bone mineral.
For 16 young adults, age and year of home
construction had a positive but statistically
insignificant effect (p > 0.05) on bone Pb.
47-59 yrs (n =116): PbB 5.8 (+3.7), tibia 14.6
(+8.3), patella 23.6 (+12.4)
60-69 yrs (n = 360): PbB 6.3 (+4.2), tibia 21.1
(+11.4), patella 30.5 (+16.9)
>70 yrs (n = 243): PbB 6.5 (+4.5), tibia 27
(+15.6), patella 38.8 (+23.5)
High Pb exposure: PbB levels (mean 23.6 ug/dL;
n = 19); lowPb exposure (mean 6.5 ug/dL;
n= 16).
A 10 ug/g increase in dentine Pb levels in
childhood was predictive of a 1 ug/g increase
in tibia Pb levels and a 5 ug/g increase in
patella PbB levels, and a 3 ug/g increase in
mean bone Pb levels among the young adults.
They concluded that Pb exposure in early life
may be used to predict elevated body burden
up to 13 yr later.
K-shell XRF may be useful for assessing low-
level Pb burdens in epidemiological studies.
Factors that remained significantly related to
higher levels of both tibia and patella Pb were
higher age and measures of cumulative
smoking, and lower levels of education.
An increase in patella Pb from the median of
the lowest to the median of the highest
quintiles (13-56 ug/g) corresponded to a rise
in PbB of 4.3 ug/dL. Bone Pb levels
comprised the major source of circulating lead
in these men.
Unexpectedly, they found that children with
high Pb exposure had a significantly higher
bone mineral density than children with low
Pb exposure. They hypothesized that this
arises from the effect of Pb on accelerating
bone maturation by inhibition of parathyroid
hormone-related peptide.
-------
Table AX4-4 (cont'd). Bone Lead Measurements in Environmentally-Exposed Subjects
Reference, Study
Location, and Period
Study Description
Lead Measurement (SD or range)
PbB in u,g/dL, Bone Pb in u,g/g Bone Mineral
Findings, Interpretation
X
United States (cont'd)
Rosen et al.
(1989)
Bronx, NY
Unknown
Kosnettetal. (1994)
Dickson City, PA
1991
Rosen etal. (1993)
Moosic and Throop, PA
1989-91
Comparison of L-shell XRF measures
and EDTA provocation test in lead-toxic
children 1-6 yr old. Eligible if PbB 25-
55 ng/dL and erythrocyte protoporphyrin
>35 ng/dL.
Aim to determine the influence of
demographic, exposure and medical
factors on the bone Pb concentration of
subjects with environmental Pb exposure.
101 subjects (49 males, 52 females; aged
11 to 78 yrs) recruited from 49 of 123
households geographically located in a
suburban residential neighborhood.
Tibia. Multiple regression.
Suburban population (Throop, n = 269)
exposed to unusually high emissions
during 1963-81 from nearby battery
recycling/secondary smelter. Moosic
served as control community.
Approximately 9% children aged 5-12 yr,
15% 13-17 yr, 40% > 18 yr. Soil and
PbB, L-shell XRF.
Negative EDTA test results (n = 30): PbB 30 + 5
Hg/dL, tibia Pb 12 + 2 ng/g (range 7-52).
Positive EDTA test results (n = 29): PbB 39 + 8
Hg/dL, tibia Pb 37 + 3 ng/g (range 7-200).
Mean (SD) bone Pbl2.7 (14.6).
Log-transformed bone Pb highly correlated with
age (r = 0.71; p < 0.0001). Gender differences in
log-transformed bone Pb values were
insignificant up until the 6th decade.
No significant differences in tibia Pb found
among three age groups in Moosic or Throop.
Mooaic: means 5-12 yr, 6 ng/g; 13-17 yr, 8 ng/g;
>18yr,7ng/g
Throop: means 5-12 yr, 12+1 ng/g; 13-17 yr,
15 + 2|ig/g; >18yr, 12+1 ng/g.
From PbB and LXRF alone, 90% of Pb-toxic
children were correctly classified as being
EDTA-positive or -negative. LXRF may be
capable of replacing EDTA testing.
Bone Pb showed no significant change up to
age 20 yr, increased with the same slope in
men and women between ages 20 and 55 yrs,
and then increased at a faster rate in men older
than 55 yrs.
No change in bone Pb with age. Baseline
values for bone Pb in the environmentally
exposed population of Moosic can serve as a
reference baseline for contemporary bone Pb
levels in similar communities in the USA.
Stokes etal. (1998)
Bunker Hill, ID; Spokane,
WA
1994
Examined whether environmental
exposure to Pb during childhood was
associated with current adverse
neurobehavioral effects. K-shell XRF.
Formerly exposed as children 19-30 yr
(n = 238, age 19-30 yr).
Referents (n = 258)
Exposed group:
PbB 2.9 ng/dL; tibia Pb 4.6 ng/g.
Referent group:
PbB 1.6 ng/dL; tibia Pb 0.6 ng/g.
-------
Table AX4-4 (cont'd). Bone Lead Measurements in Environmentally-Exposed Subjects
Reference, Study
Location, and Period
Study Description
Lead Measurement (SD or range)
PbB in u,g/dL, Bone Pb in u,g/g Bone Mineral
Findings, Interpretation
X
United States (cont'd)
McNeill et al. (2000)
Idaho and Washington
1994
To determine if high Pb exposure in
childhood persisted until adulthood.
262 exposed subjects and 268 age and
sex matched controls aged 19-29 yr.
Tibia bone Pb, cumulative PbB index.
Inverse weighted group mean data,
linear regressions.
Group inverse weighted mean (SEM).
Males: Exposed 4.54 (0.31); controls 0.03 (0.31) ug
Pb/g bone mineral.
Females: Exposed 5.61 (0.43); controls 1.67 (0.43)
ug Pb/g bone mineral.
Lead from exposure in early childhood had
persisted in the bone matrix until adulthood.
Bone Pb significantly correlated with age for
exposed groups. No significant correlation in
regressions for control groups with age.
Exposed subjects had group bone Pb levels
significantly higher (p < 0.005) than control
subjects in 7 of 11 age groups. Exposed
subjects had increased current PbB
concentrations that correlated significantly
with bone Pb values. Incorporation rate of Pb
into bone 0.039 (0.003) (pig Pb/g bone
mineral)/ ug/dL yr).
Mexico
Farias etal. (1998)
Mexico City and suburbs
1995-96
Examined the relation of blood and
tibia bone Pb levels to Pb
determinants in 100 adolescents aged
11 to 21 yr. LOWESS smoothing,
multivariate regressions.
Females (n = 62): PbB 6.4 (+3.2), tibia 5.5(+8.6).
Males (n = 36): PbB 9.1 (+5.5), tibia 3.8 (+5.5).
25 subjects had bone Pb < 0.
Bone Pb accounted for 4.1% of variation in PbB.
Increase in bone Pb of 21.6 ug/g was associated with
an increase in PbB of 1.2 ug/dL.
Predictors of bone Pb included higher traffic
density near the home, mother's smoking
history, and time spent outdoors. Predictors
of log-transformed PbB included bone Pb
levels, male sex, use of Pb-glazed ceramics,
and living in Mexico City. BonePb
accumulated over time constitutes a moderate
source of circulating Pb during adolescence
PbB = blood lead.
-------
Table AX4-5. Bone Lead Measurements in Occupationally-Exposed Subjects
Reference, Study
Location, and Period
Study Description
Lead Measurement (SD or range)
PbB in u,g/dL, Bone Pb in u,g/g Bone Mineral
Findings, Interpretation
X
to
United States
Huetal. (1994)
U.S.
1991
Schwartz et al. (2000b)
U.S.
1995
Popovich et al. (2005)
Idaho
Construction workers aged 23 to 67 yr
(n=19). Examination of Bone Pb
and PbB as predictors of blood
pressure in construction workers.
Multivariate linear regression,
LOWESS smoothing.
Retired organolead employees (n =
543). Aim to determine influence of
PbB, chelatable Pb, and tibial Pb on
systolic and diastolic blood pressure.
108 former female smelter employees
and 99 referents to assess the PbB
versus bone Pb relationship.
PbB8.3(+4.0),tibiaPb9.£
13.9 (+13.6).
(+9.5), patella Pb
PbB 4.6 (+2.6), tibia Pbl4.4 (+9.3).
Exposed: PbB 2.73 (+2.39), tibia 14.4 (+0.5)
Referents: PbB 1.25 (+2.10), tibia 3.22 (+0.50)
Pb concentrations in tibia and blood significantly
higher in the exposed group. Endogenous release
rate (ug Pb per dL blood/ug Pb/g bone) in
postmenopausal women was double the rate found in
premenopausal women (0.132 + 0.019 vs. 0.067 +
0.014).
Tibia Pb was not associated with any blood
pressure measures.
Higher tibia bone Pb (and PbB) was
associated with use of estrogen (present or
former) in both the whole referent group and
postmenopausal women in the referent group.
Canada
Fleming etal. (1997)
Canada
1994
Primary smelter workers, 367 active
and 14 retired.
PbB in 204 workers returning after a
10-mo strike ended in 1991.
Cumulative PbB index, K-shell
measures with 109Cd source.
Active (1975-81) median PbB 16.0, (1987-92)
median PbB 8.0, tibia range 0-150, calcaneus 0-250.
Retired tibia range 20-120, calcaneus 40-220.
Bone Pb-cumulative PbB index slopes larger for
retired compared with active workers, but not
significant.
Nonlinearities in cumulative PbB index and
tibia and calcaneus Pb suggest differences in
Pb transfer from whole blood to bone among
smelter employees. Contribution to PbB from
bone stores at any instant in time is similar for
all occupationally exposed populations, active
or retired.
Age-related variations in bone turnover are
not a dominant factor in endogenous exposure
of male lead workers. More rapid absorption
of Pb in calcaneus than tibia.
-------
Table AX4-5 (cont'd). Bone Lead Measurements in Occupationally-Exposed Subjects
Reference, Study
Location, and Period
Study Description
Lead Measurement (SD or range)
PbB in ug/dL, Bone Pb in ug/g Bone Mineral
Findings, Interpretation
Canada (cont'd)
Fleming et al. (1998)
Canada
1994
X
Brito et al. (2000)
Canada
1993-98
Primary smelter.
ALAD 1-1 (n = 303) and ALAD1-2, 2-2
(n=65).
PbB, serum Pb, cumulative PbB index,
ALAD genotype, K-shell measures with
109Cd source.
Aims were to: (i) investigate the long-term
human Pb metabolism by measuring the
change of Pb concentration in the tibia and
calcaneus between 1993 and 1998; and (ii)
assess whether improved industrial hygiene
was resulting in a slow accumulation of Pb
in an exposed workforce. 101 workers in a
secondary lead smelter, 51 subjects had
similar bone Pb measurements in 1993.
Most other subjects had been hired since
1993. Cumulative PbB index. Linear
regressions.
1-1: PbB 22.9, tibia 41.2, calcaneus 71.6
1-2, 2-2: PbB 25.2, tibia 42.7, calcaneus 72.3.
Slopes of linear relations of bone Pb to cumulative
PbB index were greater for workers homoallelic for
ALAD 1, indicating more efficient uptake of lead
from blood into bone; effect most significant in
calcaneus bone and for workers hired since improved
safety measures enacted in 1977 [ALAD1-1: 0.0528
+ 0.0028 and ALAD1-2 or 2-2: 0.0355 + 0.0031
(p< 0.001)].
Repeats (n= 51)
1993: Tibia 39 (±19), calcaneus 64 (±36).
1998: Tibia 33 (±18), calcaneus 65 (±38).
Non-repeats (n = 50)
1998: Tibia 15 (±16), calcaneus 13 (±18).
Tibia Pb decreased significantly (p < 0.001) in the
51 subjects with repeated bone Pb measurements.
Tibia Pb in 1993 and changes in cumulative PbB index
were significant predictors of changes in tibia Pb.
An overall half-life of 15 yr (95% CI: 9, 55 yr) was
estimated. Adding continuing lead exposure and
recirculation of bone lead stores to the regression
models produced half-life estimates of 12 and 9 yr,
respectively, for release of lead from the tibia. Repeat
subjects showed no net change in calcaneus Pb after
Syr.
Decreased transfer of PbB into bone in
individuals expressing the ALAD2 allele
contrasted with increased PbB. ALAD
genotype affected lead metabolism and
potentially modified lead delivery to target
organs including the brain but ALAD
genotype did not significantly affect the net
accumulation of lead in bone.
The decrease in new exposure coupled to
release of previously stored bone Pb resulted
in a significant decrease in tibia Pb in the
repeat subjects. The rate of clearance of Pb
from the tibia of 9 to 15 yr is towards the
more rapid end of previous estimates. The
lack of a significant change in the calcaneus
Pb was surprising and if confirmed would
have implications for models of Pb
metabolism.
-------
Table AX4-5 (cont'd). Bone Lead Measurements in Occupationally-Exposed Subjects
Reference, Study
Location, and Period
Study Description
Lead Measurement (SD or range)
PbB in u,g/dL, Bone Pb in u,g/g Bone Mineral
Findings, Interpretation
X
£
Canada (cont'd)
Brito et al. (2002)
Canada
1994, 1999
Evaluated endogenous release of Pb from
bone to blood in 204 exposed subjects
resuming their duties after a 10-mo strike
in a primary lead smelter in 1991. Bone
Pb (109Cd source) measured in the tibia and
calcaneus in 1994 (Fleming etal., 1997)
and 1999. A linear model used to predict
the current PbB upon the level of lead in
bone. 327 subjects available on both
occasions. Group H higher PbB and
Group L lower PbB.
Group H: PbB 22.0, tibia 19.2 (n = 120)
Group L: PbB 20.6, tibia 82.8 (n = 45)
Group H: PbB 24.2, calcaneus 41.4 (n = 90)
Group L: PbB 20.2,calcaneus 138.2 (n = 45)
Structural analysis of data gave slopes for tibia
(2.0, 95% CI: 1.66-2.54) and calcaneus (0.19, 95%
CI: 0.16-0.23) that were significantly higher than
those predicted by the commonly used simple linear
regression method, for tibia (0.73, 95%, CI:
0.58-0.88) and calcaneus (0.08, 95% CI: 0.06-0.09).
Suggested that more Pb than previously
predicted by regression analysis is released
from bone to blood.
Europe
Somervaille et al. (1988)
England
K-shell measures with 109Cd source on
diverse Pb workers and controls
Crystal glass (n = 87); Battery plant
(n = 88); Precious metals (n = 15);
Laboratory (n = 20).
Cumulative PbB index.
Crystal glass: PbB 48.1, tibia 31.0
Battery plant: PbB 32.3, tibia 32.3
Precious metals: PbB 51.4, tibia 54.5
Laboratory: PbB 13.1, tibia 16.7
Correlation coefficients between tibia lead
and duration of employment were
consistently higher at all three factories
respectively (r = 0.86, p < 0.0001; r = 0.61,
p < 0.0001; r= 0.80, p< 0.0001). Strong
relation between tibia Pb and cumulative
PbB index among workers in factories
from which PbB histories were available.
Christoffersson et al.
(1984)
Sweden
Unknown
Lead smelter employees
Active (n = 75); Former plant (n = 32)
Finger bone measurement with 57Co
Active: median PbB 53.8 (15.5), mean tibia 43
(<20, 122)
Former: median PbB 24.9 (7.0), mean tibia 59.0
(<20,135)
Increase of bone Pb with time of
employment, no association between bone
Pb and current PbB in active workers, in
retired workers PbB rose with increasing
bone Pb.
Christoffersson et al.
(1986)
Sweden
1978-84
Retired lead workers.
Group 1: 7 smelter, 1 storage battery
monitored for 2-5 yr directly after end of
exposure.
Group 2: 6 battery, bone Pb measured 7-
13 yr after end of exposure. Finger bone
measurement with 57Co source from 4 to
9 times.
Group 1: mean initial bone Pb 97 (61, 131),
decreasing bone Pb with time half-life 6.7 yr (3.4, 15)
Group 2: mean initial bone Pb 72 (37, 96), mean
half-life 8.2 yr (2.4,oo)
Decrease of lead in bone after the end of
exposure considerably faster than estimated
earlier from various data on lead
metabolism.
-------
Table AX4-5 (cont'd). Bone Lead Measurements in Occupationally-Exposed Subjects
Reference, Study
Location, and Period
Study Description
Lead Measurement (SD or range)
PbB in u,g/dL, Bone Pb in u,g/g Bone Mineral
Findings, Interpretation
X
Europe (cont'd)
Hanninenetal. (1998)
Finland
Unknown
Erkkilaetal. (1992)
Finland
Unknown
Nilssonetal. (1991)
Sweden
1980s
Storage battery workers
Grouped into those whose PbB exceeded
50 jig/dL [High PbB (n = 28; 21 males)],
and never [Low PbB (n = 26; 22 males)].
Evaluation of neuropsychological
dysfunction.
K-shell measures with 109Cd source on acid
battery employees and controls
Active (n = 91); Former plant (n = 16);
Office (n = 38); Laboratory (n = 26). K-
shell XRF.
Group A: 7 retired smelter workers and
1 battery worker monitored for —10 yr with
11-17 finger bone measurements with
57Co.
Group B: 6 retired battery workers
monitored for up to 18.5 yr with 7-13
finger bone measurements.
High PbB: average PbB 39.3 (+8.3), tibia 35.3
(+16.6), calcaneus 100.4 (+43.1)
Low PbB: average PbB 29.0 (+6.2), tibia 19.8
(+13.7), calcaneus 78.6(+62.4)
Active: PbB 30.0 (9.5), tibia 21.1 (17), calcaneus 76.6
(55.3)
Former plant: PbB 12.2 (6.2), tibia 32.4 (34.9),
calcaneus 73.5 (57.7)
Office: PbB 6.4 (3.3), tibia 7.7 (11.3), calcaneus 14.2
(15.6)
Laboratory: PbB 3.7 (1.7), tibia 3.5 (10.S
1.2(10.6)
, calcaneus
Bone Pb values decreased over time.
A mono-exponential retention model was used.
Group A: estimated half-life for bone Pb was
6.2-27 yr.
Group B: half-life was 11-470 yr.
No relation was found between the
neuropsychological test battery and tibial
Pb.
Tibia Pb concentration increased
consistently both as a function of intensity
of exposure and duration of exposure.
Calcaneal Pb concentration strongly
dependent on the intensity rather than
duration of exposure. Biological half-life
of Pb in calcaneus <7-8 yr periods into
which the duration of exposure was split.
Retired workers: endogenous exposure to
Pb arising from skeletal burdens
accumulated over a working lifetime can
easily produce the dominant contribution to
systemic Pb concentrations once
occupational exposure has ceased.
The "shared" half-life for bone Pb was 16
(CI: 12,23) yr. These values are longer
than ones of Christoffersson et al. (1986)
for the same two groups; no "background"
values were subtracted in the latter case.
-------
Table AX4-5 (cont'd). Bone Lead Measurements in Occupationally-Exposed Subjects
Reference, Study
Location, and Period
Study Description
Lead Measurement (SD or range)
PbB in u,g/dL, Bone Pb in u,g/g Bone Mineral
Findings, Interpretation
Europe (cont'd)
Gerhardsson et al.
(1993)
Sweden
Unknown
X
Borjesson et al. (1997)
Sweden
1992
Bergdahl et al. (1998)
Sweden
1986
Erfurthetal. (2001)
Sweden
Pb smelter and truck assembly (referent)
workers; Active smelter (n = 70); Retired
smelter (n = 30); Truck assembly (n = 31);
Retired truck assembly (n = 10). K-shell
measures with 109Cd source.
Pb smelter and referent male metal
workers Active smelter (n = 71); Retired
smelter (n = 18); Referent active (n = 27);
Referent retired (n = 8). Similar cohort to
Gerhardsson et al. (1993). Finger bone
measurement with 57Co source.
Cumulative PbB index.
Secondary Pb smelter
Exposed (n = 77); Referents (n = 24). K-
shell measures with 109Cd source.
Cumulative PbB index and (calculated)
plasma Pb.
Secondary smelter
Active (n = 62); Retired (n = 15);
Referents (n = 26).
Evaluation of effects of Pb on the
endocrine system.
Finger bone measures with 57Co source.
Median values presented.
Active smelter: PbB 31.9 (5.0, 47.4), tibia 13.0
(-4.1, 72.8), calcaneus 48.6 (0.4, 217.8)
Retired smelter: PbB 9.9 (3.3, 21), tibia 39.3
(2.9, 73.4), calcaneus 100.2 (34.8, 188.9)
Truck: PbB 4.1 (1.7, 12.4), tibia 3.4
(-9.4, 13.3), calcaneus 12.2 (-12.7, 43.0)
Retired truck: PbB 3.5 (2.2,12.2), tibia 12.0
(-6.7, 23.7), calcaneus 30.2 (-7.1, 56.7)
Median values presented.
Active smelter: PbB 33.1 (8.3, 93),
bone Pb 23.0 (-13, 99)
Retired smelter: PbB 17.2 (8.9, 33.1),
bone Pb 55 (3, 88)
Active referent: PbB 3.7 (0.8, 7.0),
bone Pb 3 (-21, 16)
Retired referent: PbB 3.9 (3.1, 6.2),
bone Pb 1.5 (-3, 12)
Exposed: PbB 35.0 (14, 57), tibia 25 (5, 193),
calcaneus 52 (-20,458)
Referents: PbB 5.0 (2.9, 16). tibia 10 (-6, 36),
calcaneus 11 (-12, 61)
Median values presented.
Active: PbB 33.2 (8.3, 93.2), tibia 21 (-13,99)
Retired: PbB 18.6 (10.4, 49.7), tibia 55 (3, 88)
Referents: PbB 4.1 (0.8, 6.2), tibia 2 (-21, 14)
Higher calcaneus Pb than tibia Pb in active
lead workers suggested more rapid
absorption over time in this mainly
trabecular bone. Estimated biological half
times were 16 yr in calcaneus (95% CI:
11, 29 yr) and 27 yr in tibia (95% CI: 16,
98 yr). Strong positive correlation between
bone Pb and cumulative PbB index.
Multiple regression analyses showed bone
Pb was best described by the cumulative
PbB index, which explained 29% of the
observed variance (multiple r2) in bone Pb
in active workers and about 39% in retired
workers. Estimated biological half-life of
bone Pb among active lead workers was
5.2yr(95%CI: 3.3-13.0 yr).
Strong relationships between the tibia Pb
(r2 = 0.78) and calcaneus (r2 = 0.80) and
cumulative PbB index. Half-lives of Pb in
tibia 13-24 yr and calcaneus 12-19.
No significant associations between bone
Pb and pituitary and thyroid hormones,
serum testosterone, gonadotropin-releasing
hormone and thyroid releasing hormone.
-------
Table AX4-5 (cont'd). Bone Lead Measurements in Occupationally-Exposed Subjects
Reference, Study
Location, and Period
Study Description
Lead Measurement (SD or range)
PbB in u,g/dL, Bone Pb in u,g/g Bone Mineral
Findings, Interpretation
Europe (cont'd)
Rods etal. (1995)
Belgium
Pb smelter and others.
Active production (n = 73); Other
departments (n = 50). K-shell measures
with 109Cd source. Cumulative PbB index.
Active: PbB 42.0, tibia 66.5
Others: PbB 14.5, tibia 31.4
Strong relationship between bone Pb and
cumulative PbB index in smelter
populations (r = 0.80, p < 0.0001; age
explained <9.5% of variance). Slope of
regression equation of log bone Pb versus
log cumulative PbB index showed that
doubling of cumulative PbB index
corresponds to doubling of bone Pb.
X
Mexico
Juarez-Perez et al.
(2004)
Mexico City
1996-7
Lithographic print shop workers; Males,
n = 59, 10 females; mean age 47 yrs
Plasma Pb by ultraclean ICP-MS methods.
K-shell measures with 109Cd source.
PbB 11.9 (+5.8), tibia 27.6 (+18.1; ND-73.1
patella 46.8 (+29.3; ND-139)
Statistically significant associations
between: plasma Pb and PbB, patella Pb,
tibia Pb, age, education, use of Pb-glazed
ceramics but not air Pb, hand Pb or hygiene
index at work. Multiple linear regression
models with patella and tibia Pb as main
predictors and adjusting for PbB and
hygiene index explained 57% of variability
in plasma Pb. Negative association
between plasma Pb and hygiene index
suggest oral exposure and gastrointestinal
uptake of Pb predominant source of Pb
exposure in these subjects.
Asia
Schwartz etal. (2001)
Korea
1997-99
Korean Pb workers (798, 639 male,
164 female) and controls (135, 124 male,
1 female). Evaluation of associations
between PbB, tibia Pb, chelatable Pb, and
neurobehavioral functions. K-shell
measures with 109Cd source.
Active: PbB 32 (+15), tibia 37.2 (+40.4)
Controls: PbB 5.3 (+1.8), tibia 5.8 (+7.0).
After adjustment for covariates, tibia Pb
was not associated with neurobehavioral
test scores.
-------
Table AX4-5 (cont'd). Bone Lead Measurements in Occupationally-Exposed Subjects
Reference, Study
Location, and Period
Study Description
Lead Measurement (SD or range)
PbB in u,g/dL, Bone Pb in u,g/g Bone Mineral
Findings, Interpretation
Asia (cont'd)
Toddetal. (2001)
Korea
Korean Pb workers active (n = 723),
retired (n = 79), controls (n = 135).
Evaluation of associations between PbB,
tibia Pb, chelatable Pb.
K-shell measures with 109Cd source.
Active: median PbB 31.7, tibia 24.4
(-7.4, 337.6)
Retired: median PbB 13.5, tibia 26.4
(-6.7, 196.7)
Controls: median PbB 5.1, tibia 5.0
(-10.9,26.6)
Control women higher bone Pb than men.
Job duration, body mass index, and age
were positive predictors of tibial Pb. Rate
of increase in tibia Pb with age itself
increased with increasing age. Tibial Pb
stores in older subjects are less bioavailable
and may contribute less to PbB than tibial
stores in younger subjects.
X
PbB = blood lead.
oo
-------
Table AX4-6. Bone Lead Contribution to PbB
Reference, Study
Location, and
Period
Study Description
Lead Measurement (SD or range)
PbB in ug/dL, Bone Pb in ug/g Bone Mineral
Findings, Interpretation
X
VO
United States
Korrick et al.
(2002)
Boston, MA
1990-95
Popovic et al.
(2005)
Bunker Hill, ID
1994
Nurses' Health Study. Cross-
sectional study of 264 elderly
women; 46-54 yr (n = 80) 55-64
yr (n = 102), 65-74 yr (n = 82).
Tibia and patella Pb. Multivariate
linear regression models.
108 former female smelter
employees and 99 referents to
assess the PbB versus bone Pb
relationship
46-54 yr: PbB 2.7 (SE +0.3), tibia 10.5 (+1.0), patella
14.9 (+1.2)
55-64 yr: PbB 3.4 (+0.2), tibia 12.7 (+0.9), patella 17.0 (+1.1)
65-74 yr: PbB 3.3 (+0.3), tibia 16.4 (+0.9), patella 19.8 (+1.2).
An increase from the first to the fifth quintile of tibia Pb level
(19 ug/g) was associated with a 1.7 ug/dL increase in PbB
(p 0.0001).
Exposed: PbB 2.73 (+2.39), tibia 14.4 (+0.5)
Referents: PbB 1.25 (+2.10), tibia 3.22 (+0.50)
Pb concentrations in tibia and blood significantly higher in the
exposed group. Endogenous release rate (ug Pb per dL blood/u
Pb/g bone) in postmenopausal women was double the rate found
in premenopausal women (0.132 + 0.019 vs. 0.067 + 0.014).
Tibia and patella Pb values were significantly
and positively associated with PbB but only
among postmenopausal women who were not
using estrogens. Older age and lower parity
were associated with higher tibia Pb; only age
was associated with patella Pb. They
suggested the observed interaction of bone Pb
with estrogen status in determining PbB
supports the hypothesis that increased bone
resorption, as occurs postmenopausally
because of decreased estrogen production,
results in heightened release of bone Pb stores
into blood.
Higher tibia bone Pb (and PbB) was associated
with use of estrogen (present or former) in
both the whole referent group and
postmenopausal women in the referent group.
-------
Table AX4-6 (cont'd). Bone Lead Contribution to PbB
Reference, Study
Location, and
Period
Study Description
Lead Measurement (SD or range)
PbB in ug/dL, Bone Pb in ug/g Bone Mineral
Findings, Interpretation
Canada
Brito et al. (2000)
Canada
1993-98
X
to
o
Brito et al. (2002)
Canada
1994,1999
Aims were to: (i) investigate the
long term human Pb metabolism by
measuring the change of Pb
concentration in the tibia and
calcaneus between 1993 and 1998;
and (ii) assess whether improved
industrial hygiene was resulting in a
slow accumulation of Pb in an
exposed workforce. 101 workers in a
secondary lead smelter, 51 subjects
had similar bone Pb measurements in
1993. Most other subjects had been
hired since 1993. Cumulative PbB
index. Linear regressions.
Evaluated endogenous release of Pb
from bone to blood in 204 exposed
subjects resuming their duties after a
10-mo strike in a primary lead
smelter in 1991. Bone Pb (109Cd
source) measured in the tibia and
calcaneus in 1994 (Fleming et al.,
1997) and 1999. A linear model
used to predict the current PbB upon
the level of lead in bone.
327 subjects available on both
occasions. Group H higher PbB and
Group L lower PbB.
Repeats (n = 51)
1993: Tibia 39 (±19), calcaneus 64 (±36).
1998: Tibia 33 (±18), calcaneus 65 (±38).
Non-repeats (n = 50)
1998: Tibia 15 (±16), calcaneus 13 (±18).
Tibia Pb decreased significantly (p <0.001) in the 51 subjects with
repeated bone Pb measurements. Tibia Pb in 1993 and changes in
cumulative PbB index were significant predictors of changes in
tibia Pb. An overall half-life of 15 yr (95% CI: 9, 55 yr) was
estimated. Adding continuing lead exposure and recirculation of
bone lead stores to the regression models produced half-life
estimates of 12 and 9 yr, respectively, for release of lead from the
tibia. Repeat subjects showed no net change in calcaneus Pb after
Syr.
Group H: PbB 22.0, tibia 19.2 (n = 120)
Group L: PbB 20.6, tibia 82.8 (n = 45)
Group H: PbB 24.2, calcaneus 41.4 (n = 90)
Group L: PbB 20.2,calcaneus 138.2 (n = 45)
Structural analysis of data gave slopes for tibia (2.0, 95% CI:
1.66, 2.54) and calcaneus (0.19, 95% CI: 0.16, 0.23) that were
significantly higher than those predicted by the commonly used
simple linear regression method, for tibia (0.73, 95% CI: 0.58,
0.88) and calcaneus (0.08, 95% CI: 0.06, 0.09).
The decrease in new exposure coupled to
release of previously stored bone Pb resulted in
a significant decrease in tibia Pb in the repeat
subjects. The rate of clearance of Pb from the
tibia of 9 to 15 yr is towards the more rapid end
of previous estimates. The lack of a significant
change in the calcaneus Pb was surprising and
if confirmed would have implications for
models of Pb metabolism.
Suggested that more Pb than previously
predicted by regression analysis is released
from bone to blood.
-------
Table AX4-6 (cont'd). Bone Lead Contribution to PbB
Reference, Study
Location, and
Period
Study Description
Lead Measurement (SD or range)
PbB in ug/dL, Bone Pb in ug/g Bone Mineral
Findings, Interpretation
X
to
Mexico
Brown et al. Investigated determinants of bone Pb
(2000) and PbB of 430 lactating Mexican
Mexico City women during the early postpartum
1994-5 period and contribution of bone Pb to
PbB. Linear regression analyses.
Tellez-Rojo et al. Evaluated the hypothesis that
(2002) lactation stimulates Pb release from
Mexico City bone to blood. Cross-sectional
1994-95 examination of breastfeeding patterns
and bone Pb as determinants of PbB
among 425 lactating women (mean
age 24.8 ± 5.3 yr) for 7 mo after
delivery. Bone Pb at 1 mo
postpartum. Maternal blood samples
and questionnaire information
collected at delivery and at 1, 4, and
7 mo postpartum. Generalized
estimating equations.
PbB 9.5 (±4.5), tibia 10.2 (±10.1), patella 15.2 (±15.1).
Mean PbB decreased with time postpartum: 1 mo 9.4 (±4.4),
4 mo 8.9 (±4.0), 7 mo 7.9 (±3.3).
Tibia 10.6 (11.6 after correction for negative values), patella
15.3 (16.9 after correction). After adjustment for bone Pb and
environmental exposure, women who exclusively breastfed
their infants had PbB levels that were increased by 1.4 ug/dL
and women who practiced mixed feeding had levels increased
by 1.0 ug/dL, in relation to those who had stopped lactation.
A 10 ug Pb/g increment in patella and tibia bone Pb increased
PbB by 6.1% (95% CI: 4.2, 8.1) and 8.1% (95% CI: 5.2,
11.1), respectively.
Older age, use of Pb glazed pottery, and higher
proportion of life spent in Mexico City were
main predictors of higher tibia and patella Pb.
Women in the 90th percentile for patella Pb
had an untransformed predicted mean PbB 3.6
ug/dL higher than those in the 10th percentile.
They concluded that their results support the
hypothesis that lactation is directly related to
the amount of Pb released from bone.
Garrido-Latorre Aim was to examine the relationship
et al. (2003) of PbB levels to menopause and bone
Mexico City lead levels in 232 perimenopausal
1995 and postmenopausal women from
Mexico City. Measured bone
mineral density in addition to bone
Pb. Information regarding
reproductive characteristics and
known risk factors for PbB was
obtained using a standard
questionnaire by direct interview.
Mean age of the population was
54.7 yrs (±9.8). Linear regression
analyses.
PbB 9.2 (±4.7), tibia 14.85 (±10.1), patella 22.73 (±14.9).
A change of 10 ug Pb/g bone mineral in postmenopausal
subjects was associated with an increase in PbB of 1.4 ug/dL,
whereas a similar change in bone lead among premenopausal
women was associated with an increase in PbB of 0.8 ug/dL.
Found that postmenopausal women using
hormone replacement therapy had lower PbB
levels and higher tibia and patella bone Pb
levels than non-users; patella Pb explained the
greatest part of variations in PbB. Found no
association with PbB levels and did not
describe any relationships between bone lead
and bone density.
PbB = blood lead.
-------
Table AX4-7. Bone Lead Studies in Pregnant and Lactating Subjects
Reference, Study
Location, and
Period
Study Description
Lead Measurement (SD or range)
PbB in ug/dL, Bone Pb in ug/g Bone Mineral
Findings, Interpretation
United States
Huetal. (1996)
Boston, MA
1990
X
to
to
Rothenberg et al
(2000)
Los Angeles, CA
1995-98
Cord PbB measured in 223
women, 41 bone Pb measured
at l-4postpartum. ANOVA.
Examined bone Pb contribution to
PbB in a group of 311 immigrant
women (mean age 27.8 ±7.5 yr),
99% from Latin America, during
the 3rd trimester of pregnancy, and
1 to 2 mo after delivery. Multiple
regression, variance-weighted
least squares regression, structural
equation modeling.
Values omitted if measurement uncertainty was >10 ug/g for tibia and
15 ug/g for patella.
Cord PbB 1.19 (±1.32), maternal PbB 2.9 (±2.6), tibia 4.5 (±4.0) patella 5.8
(±4.5).
Maternal age was the only factor marginally associated with combined bone
Pb (p = 0.08) but not individually with tibia or patella Pb.
Prenatal PbB 2.2 (+4.87-1.0, geometric mean), postnatal PbB 2.8
(+4.97-1.2) (p < 0.0001), tibia 6.7(±12.5), calcaneus 8.4 (±13.2). Variance-
weighted multiple regression and structural equation models showed that
both calcaneus and tibia Pb were directly associated with prenatal PbB but
only calcaneus Pb was associated with postnatal PbB. Increasing natural log
yrs in the United States independently predicted decreasing calcaneus and
3rd trimester PbB.
Umbilical cord PbB among
women served by this Boston
hospital declined dramatically
from 1980 to 1990.
Suggest that while some
exogenous Pb sources and
modulators of PbB, such as use
of Pb-glazed pottery and calcium
in the diet, control Pb exposure
during and after pregnancy,
endogenous Pb sources from past
exposure before immigration
continue to influence PbB levels
in this cohort.
Rothenberg et al.
(2002)
Los Angeles, CA
1995-2001
Examined the effects of blood and
bone PbB on hypertension and
elevated blood pressure in the 3rd
trimester and postpartum among
1,006 mostly Latina and Afro-
American women. Multiple and
logistic regression.
Returned and eligible: 3rd trimester PbB (n = 720) 1.9 (+3.67-1.0),
postpartum PbB (n = 704) 2.3 (+4.37-1.2), tibia (n = 700) 8.0 (±11.4),
calcaneus (n = 700) 10.7 (±11.9). Returned but ineligible: 3rd trimester
PbB (n = 279) 1.9 (+4.27-0.8), postpartum PbB (n = 274) 2.3 (+4.77-1.1),
tibia (n = 263) 8.7 (±13.9), calcaneus (n = 262) 11.2 (±15.1). For each
10 ug/g increase in calcaneus Pb level, the odds ratio for 3rd trimester
hypertension (systolic blood pressure > 140 mmHg or diastolic blood
pressure >90 mmHg) was 1.86 (95% CI: 1.04, 3.32). In normotensive
subjects, each 10 ug/g increase in calcaneus Pb level was associated with a
0.70 mmHg (95% CI: 0.04, 1.36) increase in 3rd trimester systolic blood
pressure and a 0.54 mmHg (95% CI: 0.01,1.08) increase in diastolic blood
pressure after adjusting for postpartum hypertension, education,
immigration status, current smoking, current alcohol use, parity, age, and
body mass index. Tibia bone Pb was not related to hypertension or elevated
blood pressure either in the 3rd trimester or postpartum, nor was calcaneus
Pb related to postpartum hypertension or elevated blood pressure.
The authors concluded that past
Pb exposure influences
hypertension and elevated blood
pressure during pregnancy and
controlling blood pressure may
require reduction of Pb exposure
long before pregnancy.
-------
Table AX4-7 (cont'd). Bone Lead Studies in Pregnant and Lactating Subjects
Reference, Study
Location, and
Period
Study Description
Lead Measurement (SD or range)
PbB in ug/dL, Bone Pb in ug/g Bone Mineral
Findings, Interpretation
Mexico
X
to
Hemandez-Avila
etal. (1996)
Mexico City
Gonzalez-Cossio
etal. (1997)
Mexico City
Unknown
Cross-sectional investigation of
the interrelationships between
environmental, dietary, and
lifestyle histories, blood and bone
Pb levels, among 98 recently
postpartum women. Multivariate
linear regression. Age 25.6
(±6.8) yr.
Examined relationship of Pb levels
in cord blood and maternal bone to
birth weight. Umbilical cord and
maternal venous blood samples
and anthropometric and
sociodemographic data were
obtained at delivery and 1 mo
postpartum. Bone Pb at 1 mo
postpartum. Multiple regression,
LOWESS.
Background information for
calcium supplementation study
Hemandez-Avila et al. (2003).
Mother-infant pairs (n = 272).
14-20 yr (n = 24): PbB 10.4 (±4.1), tibia 11.8 (±14.9), patella 14.1 (±13.3).
21-29 yr (n = 44): PbB 10.3 (±4.8), tibia 10.7 (± 10.9), patella 17.1 (±13.4)
30-43 yr (n = 27): PbB 7.8 (± 3.7), tibia 16.3 (±8.4), patella 18.1 (±12.7).
A 34 ug/g increase in patella Pb (from the medians of the lowest to the
highest quartiles) was associated with an increase in PbB of 2.4 ug/dL.
Significant predictors of bone Pb included years living in Mexico City,
lower consumption of high calcium content foods, and nonuse of calcium
supplements for the patella and years living in Mexico City, older age, and
lower calcium intake for tibia bone. Low consumption of milk and cheese,
as compared to the highest consumption category (every day), was
associated with an increase in tibia Pb of 9.7 ug/g.
Maternal PbB 8.9 (±4.1), cord PbB 7.1 (±3.5), tibia 9.8 (±8.9), patella 14.2
(±13.2).
After adjustment for other determinants of birth weight, tibia Pb was the
only Pb biomarker clearly related to birth weight. The decline in birth
weight associated with increments in tibia Pb was nonlinear and accelerated
at the highest tibia Pb quartile. In the upper quartile, neonates were on
average, 156 g lighter than those in the lowest quartile.
Suggest that patella bone is a
significant contributor to PbB
during lactation and that
consumption of high calcium
content foods may protect
against the accumulation of Pb
in one.
Bone-lead burden is inversely
related to birth weight.
-------
Table AX4-7 (cont'd). Bone Lead Studies in Pregnant and Lactating Subjects
Reference, Study
Location, and
Period
Study Description
Lead Measurement (SD or range)
PbB in u,g/dL, Bone Pb in u,g/g Bone Mineral
Findings, Interpretation
X
to
Mexico (cont'd)
Brown et al. (2000)
Mexico City
1994-5
Chuangetal. (2001)
Mexico City
1994-95
Ettinger et al. (2004)
Mexico City
1994-95
Investigated determinants of bone
Pb and PbB of 430 lactating
Mexican women during the early
postpartum period and
contribution of bone Pb to PbB.
Linear regression analyses.
Aim to estimate the contribution
of maternal whole PbB and bone
Pb, and environmental Pb to
umbilical cord PbB (as a measure
of fetal Pb exposure). Maternal
and umbilical cord blood samples
within 12 hr of each infant's
delivery. Structural equation
modeling.
Aim to quantify the relation
between maternal blood and bone
Pb and breast-feeding status
among 310 lactating women in
Mexico City, Mexico, at 1 mo
postpartum. Breast milk
measured. Multiple linear
regression, LOWESS smoothing.
PbB 9.5 (±4.5), tibia 10.2 (±10.1), patella 15.2 (±15.1).
Bone Pb measured within 1 mo after delivery. PbB 8.45 (±3.94, n = 608),
tibia 9.67 (±9.21, n = 603), patella 14.24 (±14.19, n = 575).
Tibia and patella Pb, use of Pb glazed ceramics, and mean air Pb level
contributed significantly to plasma Pb. An increase in patella Pb and tibia
Pb was associated with increases in cord PbB of 0.65 and 0.25 ug/dL,
respectively.
Breastfeeding: PbB 9.3 (±4.4, n = 310), tibia 9.6 (±10.1, n = 303), patella
14.5 (±14.9, n = 294).
Non breastfeeding: PbB 9.3 (±4.9, n = 319), tibia 10.5 (±10.2, n = 306),
patella 15.2 (±16.1, n = 289). Breast milk geometric mean 1.1 (range
0.21-8.02) ug/L. Breast milk Pb significantly correlated with umbilical cord
Pb and maternal PbB at delivery and with maternal PbB and patella Pb at
1 mo postpartum. An interquartile range increase in patella Pb (20 ug/g)
was associated with a 14% increase in breast milk lead (95% CI: 5, 25%).
An IQR increase in tibia Pb (12.0 ug/g) was associated with a 5% increase
in breast milk lead (95% CI: - 3, 14).
Older age, use of Pb glazed
pottery, and higher proportion of
life spent in Mexico City were
main predictors of higher tibia
and patella Pb. Women in the
90th percentile for patella Pb had
an untransformed predicted
mean PbB 3.6 ug/dL higher than
those in the 10th percentile.
Suggested that maternal plasma
Pb varies independently from
maternal whole PbB.
Contributions from endogenous
(bone) and exogenous
(environmental) sources were
approximately the same.
(Plasma Pb not measured).
Suggest that even among a
population of women with
relatively high lifetime Pb
exposure, breast milk Pb levels
are low, influenced both by
current Pb exposure and by
redistribution of bone Pb
accumulated from past
environmental exposures.
-------
Table AX4-7 (cont'd). Bone Lead Studies in Pregnant and Lactating Subjects
Reference, Study
Location, and
Period
Study Description
Lead Measurement (SD or range)
PbB in ug/dL, Bone Pb in ug/g Bone Mineral
Findings, Interpretation
X
to
Mexico (cont'd)
Saninetal. (2001)
Mexico City
1994-95
Gomaa et al. (2002)
Mexico City
Unknown
Examined early postnatal growth
in a cohort of healthy breastfed
newborns in relation to maternal
bone Pb burden. 329 mother-
infant pairs sampled for umbilical
cord blood at birth and maternal
and infant venous blood at 1 mo
postpartum. Maternal evaluations
at 1 mo postpartum included Pb
measures in blood and bone.
Primary endpoints were attained
weight 1 mo of age, and weight
gain from birth to 1 mo of age.
Linear regression.
Aim to compare umbilical cord
PbB and maternal bone Pb as
independent predictors of infant
mental development (n = 197).
Prospective design. At 24 mo of
age, each infant was assessed
using the Bay ley Scales of Infant
Development-II (Spanish
Version). Multiple linear
regression.
Included in analyses (n = 329):
Infant: cord PbB 6.8 (±3.9), PbB 1 mo 5.7 (±3.0)
Maternal: PbB 9.7 (±5.2), tibia Pb 10.1 (±10.3), patella Pb 15.2 (±15.2)
Excluded from analyses (n = 276):
Infant: cord PbB 6.3 (±3.0), PbB 1 mo 5.5 (±3.3)
Maternal: PbB 8.8 (±3.9), tibia Pb 9.75 (±10.3), patella Pb 14.2 (±17.3).
Infant PbB were inversely associated with weight gain, with an estimated
decline of 15.1 g/ug/dL of PbB. Children who were exclusively breastfed
had significantly higher weight gains; however, this gain decreased
significantly with increasing levels of patella Pb. Multivariate regression
analysis predicted a 3.6 g decrease in weight at 1 mo of age/ug Pb/g bone
mineral increase in maternal patella Pb levels.
Cord PbB 6.7 (±3.4), tibia 11.5 (±11.0), patella 17.9 (±15.2). After
adjustment for confounders, Pb levels in umbilical cord blood and patella
bone were significantly, independently, and inversely associated with the
Mental Development Index (MDI) scores of the Bailey Scale. In relation to
the lowest quartile of patella Pb, the 2nd, 3rd, and 4th quartiles were
associated with 5.4-, 7.2-, and 6.5-point decrements in adjusted MDI scores.
A 2-fold increase in cord PbB (e.g., from 5-10 ug/dL) was associated with a
3.1-point decrement in MDI score.
The authors concluded that
maternal Pb burden is negatively
associated with infant attained
weight at 1 mo of age and to
postnatal weight gain from birth
to 1 mo of age.
Suggest that higher maternal
patella bone Pb levels constitute
an independent risk factor for
impaired mental development in
infants at 24 mo of age. This
effect is probably attributable to
mobilization of maternal bone Pb
stores.
-------
Table AX4-7 (cont'd). Bone Lead Studies in Pregnant and Lactating Subjects
Reference, Study
Location, and
Period
Study Description
Lead Measurement (SD or range)
PbB in ug/dL, Bone Pb in ug/g Bone Mineral
Findings, Interpretation
Mexico (cont'd)
Hernandez-A vila
et al. (2002)
Mexico City
1994
X
to
Aim to evaluate the effects of
maternal bone Pb stores on
anthropometry at birth in 223
mother-infant pairs.
Anthropometric data were
collected within the first 12 hr
following delivery. Maternal
information was obtained 1 mo
after delivery (mean age 24.4 ± 5.4
yr). Transformed anthropometric
measurements to an ordinal 5-
category scale, and association of
measurements with other factors
evaluated with ordinal logistic-
regression models. Cumulative
Odds Model.
Cord blood 7.01 (±3.5), maternal PbB 8.82 (± 4.0), tibia 10.70 (±7.58,
adjusted for negative values), patella 15.39 (±11.18, adjusted for negative
values). Maternal PbB increased linearly by 0.096/ug of tibia Pb and
0.078/ug patella Pb. Umbilical cord PbB increased by 0.111/ug tibia Pb
and 0.061/ug patella Pb. Birth length of newborns decreased as tibia Pb
levels increased (odds ratio of 1.03/ug/g bone mineral [95% CI: 1.01,
1.06]).
Compared with women in the
lower quintiles of the distribution
of tibia Pb, those in the upper
quintile had a 79% increase in
risk of having a lower birth
length newborn (OR ratio 1.79;
95%CI: 1.10,3.22). PatellaPb
was positively related to the risk
of a low head circumference
score; this score remained
unaffected by inclusion of birth
weight. The increased risk was
1.027 Mg Pb/g bone mineral (95%
CI: 1.01,1.04). Odds ratios did
not vary substantially after the
authors adjusted for birth weight
and other important determinants
of head circumference.
Tellez-Rojo et al.
(2002)
Mexico City
1994-95
Evaluated the hypothesis that
lactation stimulates Pb release
from bone to blood.
Cross-sectional examination of
breastfeeding patterns and bone Pb
as determinants of PbB among 425
lactating women (mean age 24.8
±5.3 yr) for 7 mo after delivery.
Bone Pb at 1 mo postpartum.
Maternal blood samples and
questionnaire information
collected at delivery and at 1, 4,
and 7 mo postpartum. Generalized
estimating equations.
Mean PbB decreased with time postpartum: 1 mo 9.4 (±4.4), 4 mo 8.9
(±4.0), 7 mo 7.9 (±3.3).
Tibia 10.6 (11.6 after correction for negative values), patella 15.3(16.9 after
correction). After adjustment for bone Pb and environmental exposure,
women who exclusively breastfed their infants had PbB levels that were
increased by 1.4 ug/dL and women who practiced mixed feeding had levels
increased by 1.0 ug/dL, in relation to those who had stopped lactation.
A 10 ug Pb/g increment in patella and tibia bone Pb increased PbB by 6.1%
(95% CI: 4.2, 8.1) and 8.1% (95% CI: 5.2, 11.1), respectively.
They concluded that their results
support the hypothesis that
lactation is directly related to the
amount of Pb released from
bone.
-------
Table AX4-7 (cont'd). Bone Lead Studies in Pregnant and Lactating Subjects
Reference, Study
Location, and
Period
Study Description
Lead Measurement (SD or range)
PbB in ug/dL, Bone Pb in ug/g Bone Mineral
Findings, Interpretation
Mexico (cont'd)
Hemandez-Avila
et al. (2002)
Mexico City
1994
X
to
Hemandez-Avila
etal. (2003)
Mexico City
1994-95
Evaluated the effects that maternal
bone Pb has on anthropometry at
birth in 223 mother-infant pairs.
Anthropometric data (birth length,
head circumference) collected
within the first 12 hr following
delivery. Maternal information
was obtained 1 mo postparrum.
Transformed anthropometric
measurements to an ordinal 5-
category scale, ordinal logistic-
regression models.
Tested the hypothesis that in a
randomized trial of lactating
women a dietary calcium
supplement will lower PbB levels.
Lactating women (mean age 24 yr)
were randomly assigned to receive
either calcium carbonate (1200 mg
of elemental calcium daily) or
placebo in a double-blind trial.
Blood samples were obtained at
baseline, and 3 and 6 mo after the
trial began. Primary endpoint was
change in maternal PbB in relation
to supplement use and other
covariates with multivariate
generalized linear models for
longitudinal observations.
Participants (n = 223) Cord blood 7.01 (±3.5), maternal PbB 8.82 (±4.0),
tibia 9.83 (±8.9), patella 14.14 (±13.0).
Nonparticipants (n = 494): Cord blood 6.75 (±3.50), PbB 8.47 (±4.19).
Birth length of newboms decreased as tibia Pb levels increased. Compared
with women in the lower quintiles of the distribution of tibia Pb, those in the
upper quintile had a 79% increase in risk of having a lower birth length
newborn (odds ratio 1.79; 95% CI: 1.10, 3.22). The effect was attenuated-
but nonetheless significant- even after adjustment for birth weight. Patella
Pb was positively and significantly related to the risk of a low head
circumference score; this score remained unaffected by inclusion of birth
weight.
Lactating calcium group (n = 296): PbB 9.2 (±4.2), tibia 10.7 (±9.8), patella
16.2 (±15.7)
Lactating placebo (n = 321): PbB 9.4 (± 5.0), tibia 9.6 (±10.3), patella 13.5
(±15.1)
Women randomized to the calcium supplements experienced a small decline
in PbB of 0.29 ng/dL (95% CI: -0.85,-0.26). The effect was more
apparent among women who were compliant with supplement use and had
high patella Pb of >5 ng/g. Among this subgroup, supplement use was
associated with an estimated reduction in mean PbB of 1.16 ng/dL
(95% CI: -2.08, -0.23), an overall reduction of 16.4%.
The authors estimated the
increased risk of having a low
head-circumference score to be
1.027 ng Pb/g bone mineral (95%
CI: 1.01,1.04). Odds ratios did
not vary substantially after the
authors adjusted for birth weight
and other important determinants
of head circumference.
Among lactating women with
relatively high Pb burden,
calcium supplementation was
associated with a modest
reduction in PbB levels.
-------
Table AX4-7 (cont'd). Bone Lead Studies in Pregnant and Lactating Subjects
Reference, Study
Location, and
Period
Study Description
Lead Measurement (SD or range)
PbB in ug/dL, Bone Pb in ug/g Bone Mineral
Findings, Interpretation
Mexico (cont'd)
Tellez-Rojo et al.
(2004)
Mexico City
1997-99
X
to
oo
Tested the hypotheses that
maternal bone Pb burden is
associated with increasing
maternal whole PbB and plasma
Pb over the 3 trimesters of
pregnancy and that this association
is modified by rates of maternal
bone resorption. Urine was
analyzed for cross-linked N-
telopeptides (NTx) of type I
collagen, a biomarker of bone
resorption. Patella and tibia Pb at
1 mo postpartum. Mixed models.
Participants (n = 193):
PbB (ng/dL): initial 7.10 (±1.72), 1st trimester 6.47 (± 0.17), 2nd
trimesters.80 (±0.17), 3rd trimester 6.05 (±0.17).
Plasma (ug/L): 1st trimester 0.13 (±1.88), 2nd trimester 0.12 (± 1.95), 3rd
trimester 0.12 (± 1.88) (geometric means and SD)
Bone Pb during pregnancy:
Tibia 11.35 (±8.82, adjusted for negative values), patella 13.82 (±10.97,
adjusted for negative values).
Nonparticipants (n = 134):
PbB 6.82 (±1.75), tibia 13.71 (±9.17, adjusted for negative values), patella
11.79 (±9.75, adjusted for negative values).
Found an increasing trend for plasma Pb among women with the highest
bone Pb (>median level of 12.1 ug/g) but a decreasing trend among less-
exposed women(below the median level). The observed increase reached its
maximum among women with both the highest bone Pb and the highest
bone resorption. In comparison with women with a low bone Pb and a high
NTx level, those with a high bone Pb and a high NTx level had, on average,
an 80% higher mean plasma Pb. In the cross-sectional analyses for each
trimester of pregnancy, there was an increasingly stronger association
between bone Pb and plasma Pb (log-transformed) as pregnancy progressed.
An increase in patella lead of 10 ug/g would be associated with 9% (p =
0.07), 24% (p < 0.01), and 25% (p < 0.01) increases in plasma Pb in the 1st,
2nd, and 3rd trimesters of pregnancy, respectively. The corresponding
values for tibia lead were 8% (p = 0.16), 19% (p< 0.01), and 13% (p =
0.01), respectively. Dietary calcium intake was inversely associated with
plasma lead.
They concluded that the results
support the hypothesis of a
biologic interaction between
bone Pb burden and bone
resorption. They also suggest
that as pregnancy progresses,
bone Pb may be mobilized
increasingly into plasma.
-------
Table AX4-7 (cont'd). Bone Lead Studies in Pregnant and Lactating Subjects
Reference, Study
Location, and
Period
Study Description
Lead Measurement (SD or range)
PbB in ug/dL, Bone Pb in ug/g Bone Mineral
Findings, Interpretation
X
to
VO
Mexico (cont'd)
Moline et al. (2000)
Morelos, Mexico
1999
Pilot study to assess the body
burden of lead in 24 Mexican
women (age 21-34 yr) who were
lactating. Demographic and
reproductive characteristics of
women and potential sources of
lead exposure were gathered by a
direct interview. Multiple
regression. Average time of
lactation 22 (±17) months.
PbB 4.6 (± 2.0, geometric mean), tibia 9.2 (±4.2), patella 14.8 (±8.0),
calcaneus 11.7 (±11.2). An inverse relationship was noted between months
of lactation and age-adjusted calcaneus lead level (p = 0.001).
No association was observed between age-adjusted patella or tibia lead level
and months of lactation (p = 0.15).
This pilot study provides further
limited evidence for the
hypothesis that Pb mobilization
occurs during lactation.
PbB = blood lead.
-------
Reference, Study
Location, and
Period
Table AX4-8. Bone Lead Studies of Menopausal and Middle-aged to Elderly Subjects
Study Description
Lead Measurement (SD or range)
PbB in u,g/dL, Bone Pb in u,g/g Bone Mineral
Findings, Interpretation
United States
X
oo
o
Huetal. (1996)
Boston, MA
1991+
Kim etal. (1997)
Boston, MA
1991-95
Normative Aging Study.
Subjects were middle-aged and
elderly men who had community
(nonoccupational) exposures to lead.
Cross-sectional. Backwards
elimination multivariate regression
models that considered age, race,
education, retirement status, measures
of both current and cumulative
smoking, and alcohol consumption.
Normative Aging Study (n = 70).
Aim to examine age and secular
trends in bone and PbB levels of
community-exposed men aged 52-83
yr. Bone and PbB levels measured
twice, with a 3-yr interval.
47-59 yr: (n = 116): PbB 5.8 (+3.7), tibia 14.6 (+8.3),
patella 23.6 (+12.4)
60-69yr: (n=360): PbB 6.3 (+4.2), tibia 21.1
(+11.4), patella 30.5 (+16.9)
>70yr: (n = 243): PbB 6.5 (+4.5), tibia 27 (+15.6),
patella 38.8 (+23.5)
PbB 6.7 (+1.8), tibia 17.5 (+2.0), patella 29.1 (+1.8)
3 yr later: PbB 5.1 (+1.4), tibia 17.9 (+1.7), patella
22.2 (+1.8)
Factors that remained significantly related to higher
levels of both tibia and patella Pb were higher age
and measures of cumulative smoking, and lower
levels of education. An increase in patella Pb from
the median of the lowest to the median of the
highest quintiles (13-56 ug/g) corresponded to a
rise in PbB of 4.3 ug/dL. Bone Pb levels
comprised the major source of circulating lead in
these men.
Cross-sectional analysis of each set of
measurements indicated that, on average, a 1-year-
older individual would have 2.7% and 2.4-3.2%
higher levels of Pb in patella and tibia,
respectively. Secular trend over time was
decreasing for patella Pb levels and stable for tibia
Pb levels.
Cheng etal. (1998)
Boston, MA
1991-95
Normative Aging Study (n = 747).
Aim to examine relationships of
nutritional factors to body Pb burden.
Cross-sectional.
Multiple regression models adjusting
for age, education level, smoking, and
alcohol consumption.
PbB 6.2 (± 4.1), tibia 21.9 (± 13.3), patella
32.0 (±19.5).
Multiple regression models men in the lowest quintile
of total dietary intake levels of vitamin D (including
vitamin supplements) (<179 i.u./day) had mean tibia
and patella Pb levels 5.6 ug/g and 6.0 ug/g/ higher
than men with intake in the highest quintile (>589
i.u./day). Higher calcium intake was associated with
lower bone Pb levels, but this relation became
insignificant when adjustment was made for vitamin
D. Subjects in the lowest vitamin C intake quintile
(<109 mg/day) had a mean PbB level 1.7 ug/dL higher
than men in the highest quintile (>339 mg/day), while
men in the lowest iron intake quintile (<10.9 mg/day)
had a mean PbB level 1.1 ug/dL higher than men in
the highest quintile (>23.5 mg/day).
Also observed inverse associations of PbB levels
with total dietary intake of vitamin C and iron.
Suggested that low dietary intake of vitamin D
may increase Pb accumulation in bones, while
lower dietary intake of vitamin C and iron may
increase PbB.
-------
Table AX4-8 (cont'd). Bone Lead Studies of Menopausal and Middle-aged to Elderly Subjects
Reference, Study
Location, and
Period
Study Description
Lead Measurement (SD or range)
PbB in ug/dL, Bone Pb in ug/g Bone Mineral
Findings, Interpretation
United States (cont'd)
Hu et al. (2001) Normative Aging Study. Aim to
Boston, MA determine if ALAD polymorphism is
1991+ associated with altered levels of lead
in bone and blood. Multivariate
linear regression models controlling
for age, education, smoking, alcohol
ingestion, and vitamin D intake.
ALAD 1-1 (n = 608): PbB 6.3(+4.1), tibia 22.2
(+13.9), patella 32.2 (+19.9)
ALAD 1-2/2-2 (n = 118): PbB 5.7 (+4.2), tibia 21.2
(+10.9), patella 30.4 (+17.2)
ALAD 1-1 genotype was associated with cortical
bone lead levels that were 2.55 ug/g (95% CI: 0.05,
5.05) higher than those of the variant allele carriers.
X
No significant differences by genotype with respect
to Pb levels in trabecular bone or blood. In
stratified analyses and a multivariate regression
model that tested for interaction, the relationship
of trabecular bone Pb to PbB appeared to be
significantly modified by ALAD genotype, with
variant allele carriers having higher PbB levels, but
only when trabecular bone Pb levels >60 ug/g.
The authors suggest that the variant ALAD-2 allele
modifies lead kinetics possibly by decreasing lead
uptake into cortical bone and increasing the
mobilization of lead from trabecular bone.
Oliveira et al. (2002)
Boston, MA
1991-98
Normative Aging Study.
To determine if seasonal fluctuations
in PbB levels are related to increased
mobilization of bone Pb stores during
the winter months. Measurements of
blood and bone Pb during the high
sun exposure months of May-August
(summer; n = 290); the intermediate
sun exposure months of March, April,
September, and October (spring/fall;
n = 283); and the low sun exposure
months of November-February
(winter; n= 191).
Mean PbB levels were slightly lower in summer
(5.8 ±3.4 ug/dL) compared with winter (6.6 ± 4.7
ug/dL). Mean bone Pb levels were higher during the
summer than the winter months: 23.9 (±15.2) and
20.3 (±11.3) ug/g respectively for the tibia and
34.3 (±22.8) and 29.0 (±16.2) ug/g respectively for
patella.
Found a significant interaction between season and
bone Pb with bone Pb during the winter months
exerting an almost 2-fold greater influence on PbB
levels than during the summer months. The
authors attributed this to increased mobilization of
endogenous bone Pb stores arising potentially from
decreased exposure to sunlight, lower levels of
activated vitamin D and enhanced bone resorption.
-------
Table AX4-8 (cont'd). Bone Lead Studies of Menopausal and Middle-aged to Elderly Subjects
Reference, Study
Location, and
Period
Study Description
Lead Measurement (SD or range)
PbB in u,g/dL, Bone Pb in u,g/g Bone Mineral
Findings, Interpretation
X
oo
to
United States (cont'd)
Korrick et al. (2002)
Boston, MA
1990-95
Tsaihetal. (1999)
Boston, MA
1991-97
Nurses' Health Study.
Cross-sectional study of 264 elderly
women; 46-54 yr (80) 55-64 yr (102),
65-74 yr (82). Tibia and patella Pb.
Multivariate linear regression models.
Normative Aging Study.
Aim to evaluate hypothesis that bone
and erythrocyte Pb make independent
contributions to urine Pb excreted
over 24 hour. Urine used as a proxy
for plasma Pb.
Age range 53-82 yr (n = 71).
Generalized additive model.
46-54 yr: PbB 2.7 (SE +0.3), tibia 10.5 (+1.0), patella
14.9 (+1.2)
55-64 yr: PbB 3.4 (+0.2), tibia 12.7 (+0.9), patella
17.0 (+1.1)
65-74 yr: PbB 3.3 (+0.3), tibia 16.4 (+0.9), patella
19.8 (+1.2).
An increase from the first to the fifth quintile of tibia
Pb level (19 ug/g) was associated with a 1.7 ug/dL
increase in PbB (p = 0.0001).
PbB: 5.94 (±3.0), tibia 21.7 (±10.9), patella 31.1
(±15.1), urinary Pb 5.69 (±1.9) ^g/day. Both
erythrocyte Pb and bone Pb variables remained
independently and significantly associated with
urinary Pb.
Tibia and patella Pb values were significantly and
positively associated with PbB but only among
postmenopausal women who were not using
estrogens. Older age and lower parity were
associated with higher tibia Pb; only age was
associated with patella Pb. They suggested the
observed interaction of bone Pb with estrogen
status in determining PbB supports the hypothesis
that increased bone resorption, as occurs
postmenopausally because of decreased estrogen
production, results in heightened release of bone Pb
stores into blood.
Finding suggests that bone influences plasma Pb in
a manner that is independent of the influence of
erythrocytic lead on plasma Pb. Reinforces
superiority of bone Pb over PbB in predicting some
chronic forms of toxicity may be mediated through
bone's influence on plasma Pb. Urinary lead might
be useful as a proxy for plasma Pb.
Wright et al. (2004)
Boston, MA
1991-97
Normative Aging Study. Aim to
evaluate if hemochromatosis gene
(HFE) was associated with body lead
burden. Tibia and patella bone Pb.
DNA samples genotyped.
Multivariate linear regression
analyses.
Of 730 subjects, 94 (13%) carried the C282Y
variant and 183 (25%) carried the H63D variant.
In multivariate analyses that adjusted for age,
smoking, and education, having an HFE variant allele
was an independent predictor of significantly lower
patella Pb levels (p< 0.05).
Suggested that HFE variants have altered kinetics
of Pb accumulation after exposure and these effects
may be mediated by alterations in Pb toxicokinetics
via iron metabolic pathways regulated by the HFE
gene product and body iron stores.
-------
Table AX4-8 (cont'd). Bone Lead Studies of Menopausal and Middle-aged to Elderly Subjects
Reference, Study
Location, and
Period
Study Description
Lead Measurement (SD or range)
PbB in ug/dL, Bone Pb in ug/g Bone Mineral
Findings, Interpretation
X
United States (cont'd)
Lin et al. (2004) Community Lead Study. Measured PbB
Boston, MA and bone Pb levels among minority
1999-2000 individuals from Boston. Compared with
earlier studies of predominantly white
subjects, the 84 volunteers in this study
(33:67 male to female ratio; 31-72 yrs of
age) had similar educational,
occupational, and smoking profiles and
mean blood, tibia, and patella Pb levels.
LOWESS smoothing curves. Multiple
linear regression analyses to predict
blood, tibia and patella Pb.
Berkowitz et al. Longitudinal study of 91 premenopausal
(2004) and perimenopausal women aged
New York > 30 yrs of age from New York who
1994-99 were undergoing surgical menopause
(baseline; n 84) to determine if bone Pb
values decrease and PbB values increase
during menopause. Tibia Pb
concentrations measured at baseline, 6
mo (70) and 18 mo (62) post surgery.
Schafer et al. Evaluated the relations among PbB, tibia
(2005) Pb, and homocysteine levels by cross-
Baltimore, MD sectional analysis among subjects in the
Baltimore Memory Study, a longitudinal
study of 1, 140 randomly selected
residents in Baltimore, MD, aged 50-70
yr and 66.0% female, 53.9% white, and
41.4% black or African American.
Multiple linear regression analyses.
<45 yr (n = 28): PbB 2.0 (±1.2), tibia 8.3 (±8.4),
patella 8.9 (±14.3)
46-60 yr (n = 41): PbB 2.8 (±1.7), tibia 10.8 (±11.5),
patella 11.8 (±11.4)
61-75 yr(n= 15): PbB 5.3 (±3.2),tibia21.7 (±8.6),
patella 30.9 (±15.7)
Slopes of the univariate regressions of blood, tibia, and
patella lead versus age were 0.10 ug/dL/yr (p < 0.001),
0.45 ug/g/yr (p O.001), and 0.73 ug/g/yr (p < 0.001),
respectively.
Baseline: Median PbB 2.5 (0.3, 11.7), tibia 6.1
(-22.2, 36.4)
6 mo: PbB 3.2 (0.4, 12.0), tibia 6.8 (-14.2, 29.0)
18 mo: PbB 3.1 (0.5, 9.1), tibia 5.8 (-15.4, 24.2)
PbB 3.5 (±2.4) ug/dL, tibia 18.9 (±12.5) ug/g,
homocysteine 10.0 (±4.1) ^mol/L. Tibia lead was
modestly correlated with PbB (Pearson r = 0.12,
p < 0.01) but was not associated with homocysteine
levels.
Analyses of smoothing curves and regression lines
for tibia and patella Pb suggested an inflection
point at 55 yr of age, with slopes for subjects
>55 yr of age that were not only steeper than those
of younger subjects but also substantially steeper
than those observed for individuals >55 yr of age in
studies of predominantly white participants.
Marginal decline in tibia Pb values between 6 and
18 mo post surgery for women who took estrogen
replacement therapy (ERT) but not for those who
did not take ERT. They concluded that there was
no substantial mobilization of Pb (from the tibia)
during menopause but common ERT use may have
masked this effect, the amounts of Pb released
were too low to detect in blood, or the numbers of
subjects was too small to detect an effect.
Suggested that homocysteine could be a
mechanism that underlies the effects of lead on the
cardiovascular and central nervous systems,
possibly offering new targets for intervention to
prevent the long-term consequences of lead
exposure.
-------
Table AX4-8 (cont'd). Bone Lead Studies of Menopausal and Middle-aged to Elderly Subjects
Reference, Study
Location, and
Period
Study Description
Lead Measurement (SD or range)
PbB in ug/dL, Bone Pb in ug/g Bone Mineral
Findings, Interpretation
United States (cont'd)
Kosnett et al.
(1994)
Dickson City, PA
X
Popovic et al.
(2005)
Bunker Hill, ID
1994
Aim to determine the influence of
demographic, exposure and medical
factors on the bone Pb concentration of
subjects with environmental Pb exposure.
101 subjects (49 males, 52 females; aged
11 to 78 yrs) recruited from 49 of 123
households geographically located in a
suburban residential neighborhood.
108 former female smelter employees
and 99 referents to assess the PbB versus
bone Pb relationship.
Log-transformed bone Pb highly correlated with age
(r= 0.71; ps 0.0001).
Exposed: PbB 2.73 (+2.39), tibia 14.4 (+0.5)
Referents: PbB 1.25 (+2.10), tibia 3.22 (+0.50)
Pb concentrations in tibia and blood significantly
higher in the exposed group. Endogenous release rate
(Hg Pb per dL blood/ |ig Pb/g bone) in
postmenopausal women was double the rate found
in premenopausal women (0.132 + 0.019 versus
0.067 + 0.014).
Bone Pb showed no significant change up to age
20 yr, increased with the same slope in men and
women between ages 20 and 55 yr, and then
increased at a faster rate in men older than 55 yr.
Higher tibia bone Pb (and PbB) was associated
with use of estrogen (present or former) in both the
whole referent group and postmenopausal women
in the referent group.
Canada
Webber et al. Tested hypothesis that women on
(1995) hormone replacement therapy should
Canada have higher bone Pb content and lower
Unknown plasma Pb as hormone replacement
therapy would suppress the transfer of
endogenous Pb to the circulation.
56 women, some using hormone
replacement therapy over ~4 yrs.
Low dose hormone replacement therapy (n = 15):
PbB 4.08 (±1.60), tibia 19.37 (±8.62), calcaneus 24.02
(±10.88)
Moderate dose hormone replacement therapy (n = 11):
PbB 5.22 (±3.36), tibia 16.80 (±11.68), calcaneus
23.83 (±14.18)
Calcium only (n = 22): PbB 4.6 (±1.59), tibia 11.13
(±6.22), calcaneus 21.12 (±13.55)
Women not taking hormones had significantly
lower Pb values in cortical bone compared to
all women on hormone replacement therapy
(p = 0.007). Showed higher tibia Pb levels but no
increase in calcaneus Pb level or decrease in PbB.
-------
Table AX4-8 (cont'd). Bone Lead Studies of Menopausal and Middle-aged to Elderly Subjects
Reference, Study
Location, and
Period
Study Description
Lead Measurement (SD or range)
PbB in u,g/dL, Bone Pb in u,g/g Bone Mineral
Findings, Interpretation
X
Mexico
Garrido-Latorre
etal. (2003)
Mexico City
1995
Aim was to examine the relationship of
PbB levels to menopause and bone lead
levels in 232 perimenopausal and
postmenopausal women from Mexico
City. Measured bone mineral density in
addition to bone Pb. Information
regarding reproductive characteristics
and known risk factors for PbB was
obtained using a standard questionnaire
by direct interview. Mean age of the
population was 54.7 yrs (±9.8). Linear
regression analyses.
PbB 9.2 (±4.7), tibia 14.85 (±10.1), patella 22.73
(±14.9).
A change of 10 |ig Pb/g bone mineral in
postmenopausal subjects was associated with an
increase in PbB of 1.4 ng/dL, whereas a similar
change in bone lead among premenopausal women
was associated with an increase in PbB of 0.8 ng/dL.
Found that postmenopausal women using hormone
replacement therapy had lower PbB levels and
higher tibia and patella bone Pb levels than non-
users; patella Pb explained the greatest part of
variations in PbB. Found no association with PbB
levels and did not describe any relationships
between bone lead and bone density.
Australia
Gulson et al. Environmentally exposed females (n = 7)
(2002) and males (n = 3) aged 44-70 yr. Treated
Sydney, Australia for 6 mo with the bisphosphonate
2000 alendronate. PbB and isotopic ratios
measured by TIMS for 6 mo prior to
treatment and 12 mo post-treatment.
Bone mineral density and bone markers
including NTX measured.
Found a decrease in PbB concentrations and changing
PbB isotopic composition in the direction predicted
during treatment. Upon cessation of treatment, PbB
increased and the isotopic compositions changed.
Results consistent with changes in bone remodeling
associated with bisphosphonate use.
PbB = blood lead.
-------
Table AX4-9. Lead in Deciduous Teeth from Urban and Remote Environments
Reference, Study
Location, and Period
Study Description
Lead Measurement
Findings, Interpretation
Canada
Tsuji et al. (2001) Dentine chips from schoolchildren living
Ontario, Canada in a remote area.
Mean value of 9.2 ug/g dry weight (n = 61)
Attributed the high values to consumption of
lead contaminated game meat.
Europe
Tvinnereim et al.
(1997)
Norway
1990-94
2,746 deciduous whole teeth.
Mean 1.27 ±1.87 ug/g of dry tooth substance
Observed an —50% reduction in lead
concentrations since the 1970s.
^ Lyngbyeetal. (1991) In 2,033 teeth from 1, 848 children.
4^ Denmark
Geometric mean for the largest group from Arhus to Concluded that automobile
be 8.4 ug/g (wet weight) with similar values from
Copenhagen suburbs with a secondary lead smelter exhausts and indirect Occupational
(9.6 ug/g) and a lead battery factory (9.9 ug/g).
exposure were important sources
for the lead in dentine.
Gil et al. (1996) 220 whole deciduous and permanent teeth Permanent teeth showed higher mean values Found no gender differences.
Coruna, Spain (one per subject). (13.1 ±1.1 ug/g) than deciduous teeth (4.0 ±1.1 ug/g)
Nowak and
Chmielnicka (2000)
Poland
Compared permanent teeth from two
cohorts, one from the highly polluted
Katowice district and a control town of
Beskid.
In the control teeth, they observed decreases in lead
for incisors (41.8 ug/g) to canines (37.5 ug/g) to
molars (35.3 ug/g) to premolars (32.0 ug/g).
However, there was no difference in the mean values
for the two centers: Katowice 36.5 ± 16.3 ug/g and
Beskid 36.3 ± 11.5 ug/g.
These values are very high compared with
most other studies.
-------
Table AX4-9 (cont'd). Lead in Deciduous Teeth from Urban and Remote Environments
Reference, Study
Location, and Period
Study Description
Lead Measurement
Findings, Interpretation
Mexico
Hernandez-Guerrero
et al. (2004)
Mexico City
100 healthy deciduous teeth collected
from 2 to 13 yr old children.
Higher mean concentrations of lead in the 10-13 yr
old group (7.7 ug/g) than in other age groups and the
mean concentrations were higher in girls (7.3 ug/g)
than boys (6.3 ug/g).
No association between pollution intensity
and tooth lead.
X
Frank etal. (1990)
Alsace, Mexico
Circular biopsies 500 fj.m in diameter
punched in the vertical sections of the
crown and cervical third of each root. The
age of the European subjects ranged from
10 to 80 yrs in Europe and 12 to 29 yrs in
Mexico City. Energy-dispersive X-ray
fluorescence method to compare lead in
enamel and dentine of premolars and
permanent molars.
Compared with the European values, there were
~6 times higher inner coronal dentine and 7 to
9 times higher pulpal root dentine concentrations
for samples from Mexico City.
The authors found no significant difference in
the relationship between traffic and mean lead
values for enamel and dentine in the European
communities but a significantly higher lead
concentration in relation to age. The
differences were attributed to traffic exposure.
Asia
Karakayaetal. (1996)
Ankara, Turkey
103 whole deciduous teeth from primary
school aged children aged 7 to 12 yrs.
Significant differences in lead for urban (4.99 ± 0.46
ug/g dry weight) compared with suburban children
(1.69 ±0.25 ug/g).
-------
Table AX4-10. Lead in Deciduous Teeth from Polluted Environments
Reference, Study
Location, and Period
Study Description
Lead Measurement
Findings, Interpretation
Europe
Begerowetal. (1994)
Germany
1991
Cikrtetal. (1997)
Czech Republic
790 children aged 6 yrs old living in
urban and rural areas in western and
eastern Germany. Incisors sampled.
Compared tooth (n = 162) and PbB levels
in children living at various distances
from a lead smelter.
Lead levels of 1.50 to 1.74 ng/g from the western sector
and from 1.51 to 2.72 jig/g in the eastern sector.
Significant difference in the mean tooth lead for children
from the most contaminated zone less than 0.5 km from the
smelter (6.44 ng/g; n = 13) and those >5 km from the
smelter (1.45 ng/g; n = 36). PbB levels varied from 15.42
Hg Pb/100 ml (n = 6; 95% CI: 7.17, 33.17) close to the
smelter to 4.66 ng/100 ml (n = 165, 95% CI: 4.30, 5.04) at
larger distances.
Major decrease (40-50%) since 1976.
No descriptions of the teeth type were
available.
X
oo
oo
Australia
Gulson(1996)
Broken Hill, Australia
Gulson et al. (2004)
Lake Macquarie,
Australia
36 exposed and nonexposed children
from Broken Hill lead-zinc mining
community. Sectioned teeth into mainly
enamel (incisal section) and mainly
dentine (cervical section). Lead isotope
ratios and lead concentrations by TIMS
with isotope dilution.
10 children from six houses in a primary
zinc-lead smelter community at North
Lake Macquarie, New South Wales,
Australia. Sectioned deciduous teeth
compared with environmental samples.
Lead isotope ratios and lead
concentrations by TIMS with isotope
dilution.
For subjects with low exposure (n = 13), lead
concentrations in the incisal section ranged from 0.4 to 3.5
Hg/g with a mean and standard deviation of 1.2 ± 0.8 ng/g
(n = 13). For the cervical sections in low exposure
children, the values ranged from 0.8 to 8.3 and mean
3.7 ± 2.4 ng/g. For subjects with high exposure (n = 23),
lead concentrations in the incisal section ranged from 1.0 to
8.9 ng/g with a mean and standard deviation of 2.6 ±1.8
Hg/g. For the cervical sections in high exposure children
the values ranged from 1.5 to 31.5 ng/g and mean 13.7
± 8.0 ng/g.
PbB levels in the children ranged from 10 to 42 ng/dL and
remained elevated for a number of years. Median lead
level in the enamel section of the teeth was 2.3 ng/g with a
range from 0.6 to 7.4 ng/g; in dentine the median value was
5.3 ng/g with a range from 1.4 to 19.9
The isotopic results in dentine were
interpreted to reflect an increased lead
exposure from the lead-zinc-silver
orebody during early childhood, probably
associated with hand-to-mouth activity.
Approximately 55 to 100% of lead could
be derived from the smelter.
PbB = blood lead.
-------
Table AX4-11. Summary of Selected Measurements of Urine Lead Levels in Humans
Reference, Study
Location, and Period
Study Description
Urine Lead Measurement
Comment
X
oo
VO
United States
CDC (2005)
U.S.
1999-2002
Schwartz et al.
(1999,2000b)
U.S.
1993-1997
Rabinowitz et al.
(1976)
New York
NR
Design: national survey (NHANES IV)
stratified, multistage probability cluster design
Subjects: children and adults (>6 yrs, n = 5140)
in general population
Biomarker measured: urine lead
Analysis: ICP-MS
Design: prospective
Subjects: adult male (n= 543) former TEL
manufacture workers (age range: 42-74 yrs)
Biomarker measured: DMSA (10 mg/kg)-
provoked urine lead
Analysis: GFAAS
Design: experimental study
Subjects: adult (n:5) males, age range 25-53 yrs,
ingested 300 ug Pb/day (-50% as 204Pb) for
10-210 days
Biomarker measured: urine lead
Analysis: MS
Units: ug/g creatinine
Geometric mean (95% CI)
Age (yr) 1999-2000
>6: 0.72 (0.70, 0.74)
2465
1.17(0.98,1.41)
340
0.50 (0.46, 0.54)
719
0.72 (0.68, 0.76)
1406
0.72 (0.68, 0.76)
1227
0.72 (0.68, 0.76)
1238
n:
6-11:
n:
12-19:
n:
>20:
n:
Males:
n:
Females:
n:
Units: ug/4 hr
Arithmetic mean (SD):
>2 yr exposure: 17.1(15.7)
<2 yr exposure: 20.4(17.9)
2001-2002
0.64 (0.60, 0.68)
2689
0.92(0.84,1.00)
368
0.40 (0.38, 0.43)
762
0.66 (0.621, 0.70)
1559
0.64(0.61,0.67)
1334
0.64(0.59,0.69)
1355
Units: ug/day
Arithmetic mean (range): 36(36-41)
Geometric mean PbB concentrations
in age strata ranged from 0.94 to
1.51 ug/dL.
Arithmetic mean (SD) PbB (ug/dL)
was 5.0 (2.8) for workers exposed
>2 yr and 2.8 (1.9) for workers
exposed <2yr. PbB was strongest
predictor or DMSA-provoked urine
lead.
Arithmetic mean (SD) tibia lead (ug/g,
XRF) was 15.6 (9.8) for workers
exposed >2 yr and 12.1 (7.7) for
workers exposed <2yr.
Arithmetic mean (range) PbB (ug/dL)
was 19.4 (16.7-25.1).
Blood-to-urine clearance estimate was
0.19 (range 0.15-0.23) L/day (from
Diamond, 1992).
-------
Table AX4-11 (cont'd). Summary of Selected Measurements of Urine Lead Levels in Humans
Reference, Study
Location, and Period
Study Description
Urine Lead Measurement
Comment
United States (cont'd)
Bergeretal. (1990)
Ohio
1983-1986
Design: cross-sectional, convenience sample Units:
Subjects: children (n= 39), age range not reported, range:
Biomarker measured: timed urine lead
Analysis: AAS
ug/day
5-70
PbB range was 22-55 ug/dL. Blood-to
urine clearance estimate was 0.07 L/day
(from Diamond, 1992).
X
Europe
Chamberlain et al.
(1978)
United Kingdom
1975-1976
Brockhaus et al. (1988)
Germany
1982-1986
Design: experimental
Subjects: adult males (n = 6), intravenous injection
of 203Pb tracer
Biomarker: urinary lead clearance
Analysis: gamma spectrometer (203Pb)
Design: cross-sectional
Subjects: children (n = 184), age range 4-11 yrs
residing in 2 areas impacted by smelting operations
Biomarker measured: urine lead
Analysis: GFAAS
Units: L/day
Arithmetic mean (range)
Blood-to-urine: 0.09(0.08-0.10)
Plasma-to-urine: 20
Units: ug/g creatinine
Geometric mean (GSD, range)
Stolberg (n = 106): 9.6 (2.3, 0.2-43.0)
Dortmund (n = 78): 6.7 (2.0, 1.6-41.0)
Geometric mean PbB levels were
~7 ug/dL.
Kosteretal. (1989)
Germany
NR
Design: cross-sectional
Subjects: adult (n = 46, 40 males) hospital
workers, age range 20-78 yr.
Biomarker measured: urine lead
Analysis: GFAAS
Units: ug/24 hr-1.73 m2 (adult body surface area)
Arithmetic mean (range): 6.8 (2.3-18.9)
Arithmetic mean (range) PbB (ug/dL)
was 7.6 (2.6-18.7).
Blood-to-urine clearance estimate was
0.15 L/day (from Diamond, 1992).
Australia
Gulson et al. (2000)
Australia
Design: longitudinal
Subjects: women (n = 58) during pregnancy,
age range 18-35 yrs
Biomarker measured: blood-to-urine clearance
Analysis: TIMS
Units: ug/h
Arithmetic mean (SD, range): 3.2 (0.8-10.2)
Geometric mean: 2.7
Reported blood-to-urine clearance
corresponds to -0.08 L/day.
-------
Table AX4-11 (cont'd). Summary of Selected Measurements of Urine Lead Levels in Humans
Reference, Study
Location, and Period
Study Description
Urine Lead Measurement
Comment
Asia
X
Arakietal. (1986,
1990)
Japan
NR
Lee etal. (1990)
Korea
NR
Schwartz et al.
(2000a), Lee et al.
(2001)
Korea
1997-1999
Design: cross-sectional
Subjects: adult (n = 19) male, gun metal foundry
workers, age range 34-59 yr.
Biomarker measured: urine lead
Analysis: AAS
Design: cross-sectional
Subjects: adults (n = 95) male workers in lead
smelting, battery manufacture, PVC-stabilizer
manufacture facilities, age range: 19-64 yrs;
reference subjects (n = 13), age range 22-54 yr.
Biomarker measured: DMSA (10 mg/kg)-
provoked urine lead
Analysis: GFAAS
Design: Cross-sectional
Subjects: Adult lead (inorganic) workers
(n = 798, 634 males), age range 18-65 yrs.
Biomarker measured: MSA (10 mg/kg)-provoked
urine lead
Analysis: GFAAS
Units: ug/24 hr
Arithmetic mean (range): 94(37-171)
Units: ug/4 hr
Arithmetic mean (SD, range)
Lead workers: 288.7(167.7, 32.4-789)
Reference: 23.7(11.5,10.5-43.5)
Units: ug/4 hr
Arithmetic mean (SD, range)
186(208,4.8-2100)
Arithmetic mean plasma concentration
was 0.67 ug/dL (range 0.37-0.92).
Plasma-to urine clearance estimate was
22 L/day.
Blood-to-urine clearance estimate was
0.33 L/day (from Diamond, 1992).
Arithmetic mean (SD, range) PbB
concentration (ug/dL) was 44.6 (12.6,
21.4-78.4) in lead workers and 5.9 (1.2,
4.0-7.2) in reference subjects.
PbB was strongest predictor or DMSA-
provoked urine lead.
Arithmetic mean (SD, range) PbB
(ug/dL) was 32.0 (15, 4-86). PbB was
strongest predictor or DMSA-provoked
urine lead.
Arithmetic mean (SD, range) tibia lead
(ug/g, XRF) was 37.1 (40.4, -7 to 338).
AAS - atomic absorption spectroscopy; PbB = blood lead; ET-AAS - electro-thermal atomic absorption spectrometry; GFAAS - graphite furnace atomic absorption
spectroscopy; ICP-AES - inductively coupled plasma/atomic emission spectroscopy; ICP-MS - inductively coupled plasma-mass spectrometry; MS - mass spectrometry;
NR - not reported; Pet - percentile; TEL -tetraethyl lead; TIMS - thermal ionization mass spectrometry.
-------
Reference, Study
Location, and
Period
Table AX4-12. Summary of Selected Measurements of Hair Lead Levels in Humans
Study Description
Hair Lead Measurement
Comment
United States
DiPietro et al. Design: Cross-sectional (random sample from NHANES
(1989) II, HHANES Stands)
GA, SC, TX, VA Subjects: adults (n = 270, 200 males; age range:
1976-1980 20-73 yrs) from general population
Biomarker measured: Hair lead
Analysis: ICP-AES
Units: ug/g Hair lead level varied with hair treatment (e.g.,
Geometric mean (10-90* Pet range) shampoo, coloring).
2.42 (<1.0-10.8)
X
Tuthill (1996) Design: Cross-sectional
MA Subjects: children (n = 277, 141 males,
NR age range 6.5-7.5 yrs)
Biomarker measured: Hair lead
Analysis: ICP-AES
Units: ug/g
O.1-0.9: 13.5%
1-1.9:40.8%
2-2.9: 25.6%
3-3.9: 9.0%
>4: 11.1%
Study examined associations between hair lead
levels and attention-deficit behaviors.
to
Europe
Annesi-Maesano
etal. (2003)
France
1985,1991-1992
Draschetal. (1997)
Germany
1993-1994
Gerhardsson et al.
(1995b)
Sweden
NR
Design: cross-sectional
Subjects: mother (mean age 29 yr)-infant pairs (n:374)
Biomarker measured: hair lead
Analysis: ICP-AES
Design: cross-sectional
Subjects: adults (n= 150, 75 males; age range: 16-93
yrs) from general population with no known occupational
exposure
Biomarker measured: hair lead (post-mortem)
Analysis: ET-AAS
Design: cross-sectional
Subjects: adult male smelter workers (n = 32) and
referents (n= 10)
Biomarker measured: hair lead (post-mortem)
Analysis: XRF
Units: ug/g
Arithmetic mean (SD):
Infant: 1.38(1.26)
Mother: 5.16(6.08)
Units: ug/g
Median (range): 0.76 (0.026-20.6)
25-75* Pet range: 0.45-1.48
Units: ug/g
Median (range):
Active workers: 8.0(1.5-29,000)
Retired workers: 2.6(0.6-9.3)
Reference: 2.05 (0.3-96)
Mean PbB concentrations were 96 ug/dL (SD 58)
in mothers and 67 (SD 48) in infant cord blood.
Infant hair-cord PbB correlation (Spearman, r)
was 0.21 (p< 0.01).
Median PbB (ug/dL) was 2.8 (range O.9-16.1).
Median temporal bone lead was 2.84 ug/g (range
0.25-22.3), Hair lead correlation (Spearman r) was
0.35 (p < 0.001) for blood, 0.10 (p > 0.05) for
temporal bone, and 0.16 (p > 0.05) for body
burden.0.512 for liver (p = 0.003) and 0.57
(p = 0.001) for kidney.
Based on reported a cumulative annual PbB index
of 1,374 ug/dL and average duration of
employment of 31.4 yrs, average PbB may have
been -44 ug/dL in workers. Hair lead correlation
(Spearman, r).
-------
X
-k
oo
Table AX4-12 (cont'd). Summary of Selected Measurements of Hair Lead Levels in Humans
Reference, Study
Location, and
Period
Study Description
Hair Lead Measurement
Comment
Europe (cont'd)
Esteban et al.
(1999)
Russia
1996
Design: cross-sectional
Subjects: children (n = 189, 110 females; age rage
1.9-10.6 yr) living in the vicinity of lead battery and
leaded glass manufacture facilities.
Biomarker measured: hair lead
Analysis: ICP-AES
Units: ng/g
Geometric mean (range):
5.4(1-39.2)
90th Pet: -15
Geometric mean PbB was 8.5 ng/dL
(range 3.1-35.7); log PbB = 1.44 + 0.35
(log hair) + 0.24 (gender), r2 = 0.20.
AAS - atomic absorption spectroscopy; PbB = blood lead; ET-AAS - electro-thermal atomic absorption spectrometry; GFAAS - graphite furnace atomic absorption
spectroscopy; HHANES - Hispanic Health and Nutrition Examination Survey; ICP-AES - inductively coupled plasma/atomic emission spectroscopy; ICP-MS - inductively
coupled plasma-mass spectrometry; NR - not reported; Pet - percentile.
-------
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&EPA
United States October 2006
Environmental Prolecllon EPA/600/R-05/144bF
Air Quality Criteria for Lead
Volume II of II
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EPA/600/R-05/144bF
October 2006
Air Quality Criteria for Lead
Volume II
National Center for Environmental Assessment-RTF Division
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, NC
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PREFACE
National Ambient Air Quality Standards (NAAQS) are promulgated by the United States
Environmental Protection Agency (EPA) to meet requirements set forth in Sections 108 and 109
of the U.S. Clean Air Act. Those two Clean Air Act sections require the EPA Administrator
(1) to list widespread air pollutants that reasonably may be expected to endanger public health or
welfare; (2) to issue air quality criteria for them that assess the latest available scientific
information on nature and effects of ambient exposure to them; (3) to set "primary" NAAQS to
protect human health with adequate margin of safety and to set "secondary" NAAQS to protect
against welfare effects (e.g., effects on vegetation, ecosystems, visibility, climate, manmade
materials, etc); and (5) to periodically review and revise, as appropriate, the criteria and NAAQS
for a given listed pollutant or class of pollutants.
Lead was first listed in the mid-1970's as a "criteria air pollutant" requiring NAAQS
regulation. The scientific information pertinent to Pb NAAQS development available at the time
was assessed in the EPA document Air Quality Criteria for Lead; published in 1977. Based on
the scientific assessments contained in that 1977 lead air quality criteria document (1977 Lead
AQCD), EPA established a 1.5 |ig/m3 (maximum quarterly calendar average) Pb NAAQS in
1978.
To meet Clean Air Act requirements noted above for periodic review of criteria and
NAAQS, new scientific information published since the 1977 Lead AQCD was later assessed in
a revised Lead AQCD and Addendum published in 1986 and in a Supplement to the 1986
AQCD/Addendum published by EPA in 1990. A 1990 Lead Staff Paper, prepared by EPA's
Office of Air Quality Planning and Standards (OPQPS), drew upon key findings and conclusions
from the 1986 Lead AQCD/Addendum and 1990 Supplement (as well as other OAQPS-
sponsored lead exposure/risk analyses) in posing options for the EPA Administrator to consider
with regard to possible revision of the Pb NAAQS. However, EPA chose not to revise the Pb
NAAQS at that time. Rather, as part of implementing a broad 1991 U.S. EPA Strategy for
Reducing Lead Exposure, the Agency focused primarily on regulatory and remedial clean-up
efforts to reduce Pb exposure from a variety of non-air sources that posed more extensive public
health risks, as well as other actions to reduce air emissions.
The purpose of this revised Lead AQCD is to critically assess the latest scientific
information that has become available since the literature assessed in the 1986 Lead
-------
AQCD/Addendum and 1990 Supplement, with the main focus being on pertinent new
information useful in evaluating health and environmental effects of ambient air lead exposures.
This includes discussion in this document of information regarding: the nature, sources,
distribution, measurement, and concentrations of lead in the environment; multimedia lead
exposure (via air, food, water, etc.) and biokinetic modeling of contributions of such exposures
to concentrations of lead in brain, kidney, and other tissues (e.g., blood and bone concentrations,
as key indices of lead exposure).; characterization of lead health effects and associated exposure-
response relationships; and delineation of environmental (ecological) effects of lead. This final
version of the revised Lead AQCD mainly assesses pertinent literature published or accepted for
publication through December 2005.
The First External Review Draft (dated December 2005) of the revised Lead AQCD
underwent public comment and was reviewed by the Clean Air Scientific Advisory Committee
(CASAC) at a public meeting held in Durham, NC on February 28-March 1, 2006. The public
comments and CASAC recommendations received were taken into account in making
appropriate revisions and incorporating them into a Second External Review Draft (dated May,
2006) which was released for further public comment and CASAC review at a public meeting
held June 28-29, 2006. In addition, still further revised drafts of the Integrative Synthesis
chapter and the Executive Summary were then issued and discussed during an August 15, 2006
CASAC teleconference call. Public comments and CASAC advice received on these latter
materials, as well as Second External Review Draft materials, were taken into account in making
and incorporating further revisions into this final version of this Lead AQCD, which is being
issued to meet an October 1, 2006 court-ordered deadline. Evaluations contained in the present
document provide inputs to an associated Lead Staff Paper prepared by EPA's Office of Air
Quality Planning and Standards (OAQPS), which poses options for consideration by the EPA
Administrator with regard to proposal and, ultimately, promulgation of decisions on potential
retention or revision, as appropriate, of the current Pb NAAQS.
Preparation of this document has been coordinated by staff of EPA's National Center for
Environmental Assessment in Research Triangle Park (NCEA-RTP). NCEA-RTP scientific
staff, together with experts from academia, contributed to writing of document chapters. Earlier
drafts of document materials were reviewed by scientists from other EPA units and by non-EPA
experts in several public peer consultation workshops held by EPA in July/August 2005.
Il-iv
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NCEA acknowledges the valuable contributions provided by authors, contributors, and
reviewers and the diligence of its staff and contractors in the preparation of this document. The
constructive comments provided by public commenters and CASAC that served as valuable
inputs contributing to improved scientific and editorial quality of the document are also
acknowledged by NCEA.
DISCLAIMER
Mention of trade names or commercial products in this document does not constitute
endorsement or recommendation for use.
II-v
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Air Quality Criteria for Lead
(Second External Review Draft)
VOLUME I
EXECUTIVE SUMMARY E-l
1. INTRODUCTION 1-1
2. CHEMISTRY, SOURCES, AND TRANSPORT OF LEAD 2-1
3. ROUTES OF HUMAN EXPOSURE TO LEAD AND OBSERVED
ENVIRONMENTAL CONCENTRATIONS 3-1
4. TOXICOKINETICS, BIOLOGICAL MARKERS, AND MODELS OF LEAD
BURDEN IN HUMANS 4-1
5. TOXICOLOGICAL EFFECTS OF LEAD IN LABORATORY ANIMALS
AND IN VITRO TEST SYSTEMS 5-1
6. EPIDEMIOLOGIC STUDIES OF HUMAN HEALTH EFFECTS
ASSOCIATED WITH LEAD EXPOSURE 6-1
7. ENVIRONMENTAL EFFECTS OF LEAD 7-1
8. INTEGRATIVE SYNTHESIS OF LEAD EXPOSURE/HEALTH
EFFECTS INFORMATION 8-1
VOLUME II
CHAPTER 4 ANNEX (TOXICOKINETICS, BIOLOGICAL MARKERS, AND
MODELS OF LEAD BURDEN IN HUMANS) AX4-1
CHAPTER 5 ANNEX (TOXICOLOGICAL EFFECTS OF LEAD IN
LABORATORY ANIMALS AND IN VITRO TEST SYSTEMS) AX5-1
CHAPTER 6 ANNEX (EPIDEMIOLOGIC STUDIES OF HUMAN HEALTH
EFFECTS ASSOCIATED WITH LEAD EXPOSURE) AX6-1
CHAPTER 7 ANNEX (ENVIRONMENTAL EFFECTS OF LEAD) AX7-1
Il-vi
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Table of Contents
Page
PREFACE II-iii
DISCLAIMER II-v
List of Tables II-x
Authors, Contributors, and Reviewers II-xxi
U.S. Environmental Protection Agency Project Team for Development of Air
Quality Criteria for Lead II-xxvii
U.S. Environmental Protection Agency Science Advisory Board (SAB) Staff
Office Clean Air Scientific Advisory Committee (CASAC) II-xxix
Abbreviations and Acronyms II-xxxi
AX5. CHAPTER 5 ANNEX (TOXICOLOGICAL EFFECTS OF LEAD IN
LABORATORY ANIMALS AND IN VITRO TEST SYSTEMS AX5-1
ANNEX TABLES AX5-2 AX5-1
ANNEX TABLES AX5-3 AX5-15
ANNEX TABLES AX5-4 AX5-37
ANNEX TABLES AX5-5 AX5-60
ANNEX TABLES AX5-6 AX5-75
ANNEX TABLES AX5-7 AX5-111
ANNEX TABLES AX5-8 AX5-121
ANNEX TABLES AX5-9 AX5-146
ANNEX TABLES AX5-10 AX5-156
ANNEX TABLES AX5-11 AX5-186
REFERENCES AX5-190
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List of Tables
Page
AX4-1 Analytical Methods for Determining Lead in Blood, Urine, and Hair AX4-2
AX4-2 Summary of Selected Measurements of PbB Levels in Humans AX4-4
AX4-3 Bone Lead Measurements in Cadavers AX4-7
AX4-4 Bone Lead Measurements in Environmentally-Exposed Subjects AX4-9
AX4-5 Bone Lead Measurements in Occupationally-Exposed Subjects AX4-12
AX4-6 Bone Lead Contribution to PbB AX4-19
AX4-7 Bone Lead Studies in Pregnant and Lactating Subjects AX4-22
AX4-8 Bone Lead Studies of Menopausal and Middle-aged to Elderly Subjects AX4-30
AX4-9 Lead in Deciduous Teeth from Urban and Remote Environments AX4-36
AX4-10 Lead in Deciduous Teeth from Polluted Environments AX4-3 8
AX4-11 Summary of Selected Measurements of Urine Lead Levels in Humans AX4-39
AX4-12 Summary of Selected Measurements of Hair Lead Levels in Humans AX4-42
AX5-2.1 Effect of Lead on Erythrocyte Morphology, Mobility, and Other
Miscellaneous Parameters AX5-2
AX5-2.2 Lead, Erythrocyte Heme Enzymes, and Other Parameters AX5-6
AX5-2.3 Lead Binding and Transport in Human Erythrocytes AX5-9
AX5-2.4 Lead Effects on Hematological Parameters AX5-10
AX5-2.5 Lead Interactions with Calcium Potassium in Erythrocytes AX5-12
AX5-2.6 Lead, Heme, and Cytochrome P-450 AX5-13
AX5-2.7 Lead, Erythrocyte Lipid Peroxidation, and Antioxidant Defense AX5-14
AX5-3.1 Summary of Key Studies on Neurochemical Alterations AX5-16
AX5-3.2 Summary of Key Studies on Neurophysiological Assessments AX5-20
II-x
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List of Tables
(cont'd)
Page
AX5-3.3 Summary of Key Studies on Changes in Sensory Function .......................... AX5-21
AX5-3 .4 Summary of Key Studies on Neurobehavioral Toxicity ................................ AX5-22
AX5-3.5 Summary of Key Studies on Cell Morphology and Metal Disposition ......... AX5-31
AX5-3.6 Key Studies Evaluating Chelati on of Pb in Brain .......................................... AX5-33
AX5-4. 1 Effect of Lead on Reproduction and Development in Mammals Effects
on Offspring [[[ AX5-38
AX5-4.2 Effect of Lead on Reproduction and Development in Mammals Effects
on Males [[[ AX5-45
AX5-4.3 Effect of Lead on Reproduction and Development in Mammals Effects
on Females [[[ AX5-55
AX5-5.1 In Vivo and In Vitro Studies of the Effects of Lead Exposure on
Production and Metabolism of Reactive Oxygen Species,
Nitric Oxide, and Soluble Guanylate Cyclease .............................................. AX5-61
AX5-5.2 Studies of the Effects of Lead Exposure on PKC Activity,
Activation, and Apoptosis [[[ AX5-66
AX5-5.3 Studies of the Effects of Lead Exposure on Blood Pressure and
Adrenergic System [[[ AX5-67
AX5-5.4 Studies of the Effects of Lead Exposure on Renin-angiotensin System,
Kallikrein-Kinin System, Prostaglandins, Endothelin, and Atrial
NatriureticPeptide (ANP) [[[ AX5-69
-------
List of Tables
(cont'd)
age
AX5-6.3 Genotoxic/Carcinogenic Effects of Lead—Carcinogenesis Animal
Cell Cultures AX5-79
AX5-6.4 Genotoxic/Carcinogenic Effects of Lead—Genotoxicity Laboratory
Animal Studies AX5-81
AX5-6.5 Genotoxic/Carcinogenic Effects of Lead—Genotoxicity Human Cell
Cultures Mutagenesis AX5-85
AX5-6.6 Genotoxic/Carcinogenic Effects of Lead—Genotoxicity Human Cell
Cultures Clastogenicity AX5-86
AX5-6.7 Genotoxic/Carcinogenic Effects of Lead—Genotoxicity Human Cell
Cultures DNA Damage AX5-88
AX5-6.8 Genotoxic/Carcinogenic Effects of Lead—Genotoxicity Animal Cell
Cultures Mutagenicity AX5-90
AX5-6.9 Genotoxic/Carcinogenic Effects of Lead—Genotoxicity Animal Cell
Cultures Clastogenicity AX5-92
AX5-6.10 Genotoxic/Carcinogenic Effects of Lead—Genotoxicity Animal Cell
Cultures DNA Damage AX5-95
AX5-6.11 Genotoxic/Carcinogenic Effects of Lead—Genotoxicity Non-mammalian
Cultures AX5-97
AX5-6.12 Genotoxic/Carcinogenic Effects of Lead—Genotoxicity as it Pertains
to Potential Developmental Effects AX5-98
AX5-6.13 Genotoxic/Carcinogenic Effects of Lead—Genotoxicity as it Pertains
to Potential Developmental Effects—Children AX5-99
AX5-6.14 Genotoxic/Carcinogenic Effects of Lead—Epigenetic Effects and Mixture
Interactions—Animal AX5-100
AX5-6.15 Genotoxic/Carcinogenic Effects of Lead—Epigenetic Effects and Mixture
Interactions—Human AX5-101
AX5-6.16 Genotoxic/Carcinogenic Effects of Lead—Epigenetic Effects and Mixture
Interactions—DNA Repair—Human AX5-102
-------
List of Tables
(cont'd)
age
AX5-6.17 Genotoxic/Carcinogenic Effects of Lead—Epigenetic Effects and Mixture
Interactions—DNA Repair—Animal AX5-103
AX5-6.18 Genotoxic/Carcinogenic Effects of Lead—Mitogenesis—Animal AX5-104
AX5-6.19 Genotoxic/Carcinogenic Effects of Lead—Mitogenesis Human and
Animal Cell Culture Studies AX5-107
AX5-6.20 Genotoxic/Carcinogenic Effects of Lead—Mitogenesis Other AX5-110
AX5-7.1 Light Microscopic, Ultrastructural, and Functional Changes AX5-112
AX5-7.2 Lead and Free Radicals AX5-114
AX5-7.3 Chelation with DMSA AX5-117
AX5-7.4 Effect of Chelator Combinations AX5-118
AX5-7.5 Effect of Other Metal son Lead AX5-119
AX5-8.1 Bone Growth in Lead-exposed Animals AX5-122
AX5-8.2 Regulation of Bone Cell Function in Animals—Systemic Effects
of Lead AX5-126
AX5-8.3 Bone Cell Cultures Utilized to Test Effects of Lead AX5-129
AX5-8.4 Bone Lead as a Potential Source of Toxicity in Altered Metabolic
Conditions AX5-136
AX5-8.5 Uptake of Lead by Teeth AX5-142
AX5-8.6 Effects of Lead on Enamel and Dentin Formation AX5-143
AX5-8.7 Effects of Lead on Dental Pulp Cells AX5-144
AX5-8.8 Effects of Lead on Teeth—Dental Caries AX5-145
AX5-9.1 Studies on Lead Exposure and Immune Effects in Humans AX5-147
AX5-9.2 Effect of Lead on Antibody Forming Cells (In Vitro Stimulation) AX5-150
-------
List of Tables
(cont'd)
age
AX5-9.3 Studies Reporting Lead-induced Suppression of Delayed Type
Hypersensitivity and Related Responses AX5-151
AX5-9.4 Effect of Lead on Allogeneic and Syngeneic Mixed Lymphocyte
Responses AX5-152
AX5-9.5 Effect of Lead on Mitogen-induced Lymphoid Proliferation AX5-153
AX5.9.6 Pattern of Lead-induced Macrophage Immunotoxicity AX5-155
AX5-10.1 Hepatic Drug Metabolism AX5-157
AX5-10.2 Biochemical and Molecular Perturbations in Lead-induced
Liver Tissue AX5-162
AX5-10.3 Effect of Lead Exposure on Hepatic Cholesterol Metabolism AX5-165
AX5-10.4 Lead, Oxidative Stress, and Chelation Therapy AX5-166
AX5-10.5 Lead-induced Liver Hyperplasia: Mediators and Molecular
Mechanisms AX5-171
AX5-10.6 Effect of Lead Exposure on Liver Heme Synthesis AX5-177
AX5-10.7 Lead and In Vitro Cytotoxicity in Intestinal Cells AX5-180
AX5-10.8 Lead and Intestinal Uptake—Effect on Ultrastructure, Motility,
Transport, and Miscellaneous AX5-181
AX5-10.9 Lead, Calcium, and Vitamin D Interactions, and Intestinal Enzymes AX5-184
AX5-11.1 Lead-binding Proteins AX5-187
-------
Authors, Contributors, and Reviewers
CHAPTER 4 ANNEX (TOXICOKINETICS, BIOLOGICAL MARKERS, AND
MODELS OF LEAD BURDEN IN HUMANS)
Chapter Managers/Editors
Dr. James Brown—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Principal Authors
Dr. Brian Gulson—Graduate School of the Environment, Macquarie University
Sydney, NSW 2109, Australia
Contributors and Reviewers
Dr. Lester D. Grant—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. John Vandenberg—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
CHAPTER 5 ANNEX (TOXICOLOGICAL EFFECTS OF LEAD IN HUMANS
AND LABORATORY ANIMALS)
Chapter Managers/Editors
Dr. Anuradha Mudipalli—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Srikanth Nadadur—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Lori White—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Principal Authors
Dr. Anuradha Mudipalli—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (Sections 5-2, 5-10)
-------
Authors, Contributors, and Reviewers
(cont'd)
Principal Authors
(cont'd)
Dr. Stephen Lasley—Dept. of Biomedical and Therapeutic Sciences, Univ. of Illinois College of
Medicine, PO Box 1649, Peoria, IL 61656 (Section 5.3)
Dr. Lori White—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (Section 5.3)
Dr. Gary Diamond— Syracuse Research Corporation, 8191 Cedar Street, Akron, NY 14001
(Section 5.4)
Dr. N.D. Vaziri—Division of Nephrology and Hypertension, University of California - Irvine
Medical Center, 101, The City Drive, Bldg 53, Room #125. Orange, CA 92868 (Section 5.5)
Dr. John Pierce Wise, Sr.—Maine Center for Toxicology and Environmental Health,
Department of Applied Medical Sciences, 96 Falmouth Street, PO Box 9300, Portland, ME
04104-9300 (Section 5.6)
Dr. Harvey C. Gonick—David Geffen School of Medicine, University of California at
Los Angeles, 201 Tavistock Ave, Los Angeles, CA 90049 (Sections 5.7, 5.11)
Dr. Gene E. Watson—University of Rochester Medical Center, Box 705, Rochester, NY 14642
(Section 5.8)
Dr. Rodney Dietert—Institute for Comparative and Environmental Toxicology, College of
Veterinary Medicine, Cornell University, Ithaca, NY 14853 (Section 5.9)
Contributors and Reviewers
Dr. Lester D. Grant—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Paul Reinhart—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Michael Davis—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. David A. Lawrence—Dept of Environmental and Clinical Immunology, Empire State Plaza
P.O. Box 509, Albany, NY 12201
-------
Authors, Contributors, and Reviewers
(cont'd)
Contributors and Reviewers
(cont'd)
Dr. Michael J. McCabe, Jr.—Dept of Environmental Medicine, University of Rochester,
575 Elmwood Avenue, Rochester, NY 14642
Dr. Theodore I. Lidsky—New York State Institute for Basic Research, 1050 Forest RD,
Staten Island, NY 10314
Dr. Mark H. Follansbee—Syracuse Research Corporation, 8191 Cedar St. Akron, NY 14001
Dr. William K. Boyes—National Health and Environmental Effects Research Laboratory,
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Philip J. Bushnell—National Health and Environmental Effects Research Laboratory,
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Ms. Beth Hassett-Sipple—Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Dr. Zachary Pekar—Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Dr. John Vandenberg—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
CHAPTER 6 ANNEX (EPIDEMIOLOGICAL STUDIES OF AMBIENT LEAD
EXPOSURE EFFECTS)
Chapter Managers/Editors
Dr. Jee Young Kim—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Dennis Kotchmar—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. David Svendsgaard—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
-------
Authors, Contributors, and Reviewers
(cont'd)
Principal Authors
Dr. David Bellinger—Children's Hospital, Farley Basement, Box 127, 300 Longwood Avenue,
Boston, MA 02115 (Section 6.10)
Dr. Margit Bleecker—Center for Occupational and Environmental Neurology, 2 Hamill Road,
Suite 225, Baltimore, MD 21210 (Section 6.3)
Dr. Gary Diamond— Syracuse Research Corporation, 8191 Cedar Street.
Akron, NY 14001 (Section 6.8, 6.9)
Dr. Kim Dietrich—University of Cincinnati College of Medicine, 3223 Eden Avenue,
Kettering Laboratory, Room G31, Cincinnati, OH 45267 (Section 6.2)
Dr. Pam Factor-Litvak—Columbia University Mailman School of Public Health, 722 West
168th Street, Room 1614, New York, NY 10032 (Section 6.6)
Dr. Vic Hasselblad—Duke University Medical Center, Durham, NC 27713 (Section 6.10)
Dr. Stephen J. Rothenberg—CINVESTAV-IPN, Merida, Yucatan, Mexico & National Institute
of Public Health, Cuernavaca, Morelos, Mexico (Section 6.5)
Dr. Neal Simonsen—Louisiana State University Health Sciences Center, School of Public Health
& Stanley S Scott Cancer Center, 1600 Canal Street, Suite 800, New Orleans, LA 70112
(Section 6.7)
Dr. Kyle Steenland—Rollins School of Public Health, Emory University, 1518 Clifton Road,
Room 268, Atlanta, GA 30322 (Section 6.7)
Dr. Virginia Weaver—Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe
Street, Room 7041, Baltimore, MD 21205 (Section 6.4)
Contributors and Reviewers
Dr. J. Michael Davis—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Lester D. Grant—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Kazuhiko Ito—Nelson Institute of Environmental Medicine, New York University School of
Medicine, Tuxedo, NY 10987
II-xxiv
-------
Authors, Contributors, and Reviewers
(cont'd)
Contributors and Reviewers
(cont'd)
Dr. Kathryn Mahaffey—Office of Prevention, Pesticides and Toxic Substances,
U.S. Environmental Protection Agency, Washington, DC 20460
Dr. Karen Martin—Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Dr. Zachary Pekar—Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Ms. Beth Hassett-Sipple—Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Dr. John Vandenberg—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
CHAPTER 7 ANNEX (ENVIRONMENTAL EFFECTS OF LEAD)
Chapter Manager/Editor
Dr. Timothy Lewis—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Principle Authors
Dr. Ruth Hull—Cantox Environmental Inc., 1900 Minnesota Court, Suite 130, Mississauga,
Ontario, L5N 3C9 Canada (Section 7.1)
Dr. James Kaste—Department of Earth Sciences, Dartmouth College, 352 Main Street, Hanover,
NH 03755 (Section 7.1)
Dr. John Drexler—Department of Geological Sciences, University of Colorado, 1216 Gillespie
Drive, Boulder, CO 80305 (Section 7.1)
Dr. Chris Johnson—Department of Civil and Environmental Engineering, Syracuse University,
365 Link Hall, Syracuse, NY 13244 (Section 7.1)
Dr. William Stubblefield—Parametrix, Inc. 33972 Texas St. SW, Albany, OR 97321
(Section 7.2)
II-XXV
-------
Authors, Contributors, and Reviewers
(cont'd)
Principle Authors
(cont'd)
Dr. Dwayne Moore—Cantox Environmental, Inc., 1550ALaperriere Avenue, Suite 103,
Ottawa, Ontario, K1Z 7T2 Canada (Section 7.2)
Dr. David Mayfield—Parametrix, Inc., 411 108th Ave NE, Suite 1800, Bellevue, WA 98004
(Section 7.2)
Dr. Barbara Southworth—Menzie-Cura & Associates, Inc., 8 Winchester Place, Suite 202,
Winchester, MA 01890 (Section 7.3)
Dr. Katherine Von Stackleberg—Menzie-Cura & Associates, Inc., 8 Winchester Place, Suite
202, Winchester, MA 01890 (Section 7.3)
Contributors and Reviewers
Dr. Jerome Nriagu—Department of Environmental Health Sciences, 109 South Observatory,
University of Michigan, Ann Arbor, MI 48109
Dr. Judith Weis—Department of Biology, Rutgers University, Newark, NJ 07102
Dr. Sharon Harper—National Exposure Research Laboratory (D205-05), U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Dr. Karen Bradham—National Research Exposure Laboratory (D205-05), U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Dr. Ginger Tennant—Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Ms. Gail Lacey—Office of Air Quality Planning and Standards, U.S. Environmental Protection
Agency, Research Triangle Park, NC 27711
Dr. John Vandenberg—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
II-xxvi
-------
U.S. Environmental Protection Agency Project Team
for Development of Air Quality Criteria for Lead
Executive Direction
Dr. Lester D. Grant (Director)—National Center for Environmental Assessment-RTF Division,
(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Scientific Staff
Dr. Lori White (Lead Team Leader)—National Center for Environmental Assessment
(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. James S. Brown—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Robert Elias—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (Retired)
Dr. Brooke Hemming—National Center for Environmental Assessment (B243-01), U.S.
Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Jee Young Kim—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Dennis Kotchmar—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Timothy Lewis—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Anuradha Muldipalli—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Srikanth Nadadur—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Paul Reinhart—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Mary Ross— National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. David Svendsgaard—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
II-xxvii
-------
U.S. Environmental Protection Agency Project Team
for Development of Air Quality Criteria for Lead
(cont'd)
Technical Support Staff
Mr. Douglas B. Fennell—Technical Information Specialist, National Center for Environmental
Assessment (B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC
27711 (Retired)
Ms. Emily R. Lee—Management Analyst, National Center for Environmental Assessment
(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Ms. Diane H. Ray—Program Specialist, National Center for Environmental Assessment
(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Ms. Donna Wicker—Administrative Officer, National Center for Environmental Assessment
(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (Retired)
Mr. Richard Wilson—Clerk, National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Document Production Staff
Ms. Carolyn T. Perry—Task Order Manager, Computer Sciences Corporation, 2803 Slater Road,
Suite 220, Morrisville, NC 27560
Mr. John A. Bennett—Technical Information Specialist, Library Associates of Maryland,
11820 Parklawn Drive, Suite 400, Rockville, MD 20852
Mr. William Ellis—Records Management Technician, InfoPro, Inc., 8200 Greensboro Drive,
Suite 1450, McLean, VA 22102
Ms. Sandra L. Hughey—Technical Information Specialist, Library Associates of Maryland,
11820 Parklawn Drive, Suite 400, Rockville, MD 20852
Dr. Barbara Liljequist—Technical Editor, Computer Sciences Corporation, 2803 Slater Road,
Suite 220, Morrisville, NC 27560
Ms. Michelle Partridge-Doerr—Publications/Graphics Specialist, TEK Systems, 1201 Edwards
Mill Road, Suite 201, Raleigh, NC 27607
Mr. Carlton Witherspoon—Graphic Artist, Computer Sciences Corporation, 2803 Slater Road,
Suite 220, Morrisville, NC 27560
-------
U.S. Environmental Protection Agency
Science Advisory Board (SAB) Staff Office
Clean Air Scientific Advisory Committee (CASAC)
Chair
Dr. Rogene Henderson*—Scientist Emeritus, Lovelace Respiratory Research Institute,
Albuquerque, NM
Members
Dr. Joshua Cohen—Faculty, Center for the Evaluation of Value and Risk, Institute for Clinical
Research and Health Policy Studies, Tufts New England Medical Center, Boston, MA
Dr. Deborah Cory-Slechta—Director, University of Medicine and Dentistry of New Jersey and
Rutgers State University, Piscataway, NJ
Dr. Ellis Cowling*—University Distinguished Professor-at-Large, North Carolina State
University, Colleges of Natural Resources and Agriculture and Life Sciences, North Carolina
State University, Raleigh, NC
Dr. James D. Crapo [M.D.]*—Professor, Department of Medicine, National Jewish Medical and
Research Center, Denver, CO
Dr. Bruce Fowler—Assistant Director for Science, Division of Toxicology and Environmental
Medicine, Office of the Director, Agency for Toxic Substances and Disease Registry, U.S.
Centers for Disease Control and Prevention (ATSDR/CDC), Chamblee, GA
Dr. Andrew Friedland—Professor and Chair, Environmental Studies Program, Dartmouth
College, Hanover, NH
Dr. Robert Goyer [M.D.]—Emeritus Professor of Pathology, Faculty of Medicine, University of
Western Ontario (Canada), Chapel Hill, NC
Mr. Sean Hays—President, Summit Toxicology, Allenspark, CO
Dr. Bruce Lanphear [M.D.]—Sloan Professor of Children's Environmental Health, and the
Director of the Cincinnati Children's Environmental Health Center at Cincinnati Children's
Hospital Medical Center and the University of Cincinnati, Cincinnati, OH
Dr. Samuel Luoma—Senior Research Hydrologist, U.S. Geological Survey (USGS),
Menlo Park, CA
II-xxix
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U.S. Environmental Protection Agency
Science Advisory Board (SAB) Staff Office
Clean Air Scientific Advisory Committee (CASAC)
(cont'd)
Members
(cont'd)
Dr. Frederick J. Miller*—Consultant, Gary, NC
Dr. Paul Mushak—Principal, PB Associates, and Visiting Professor, Albert Einstein College of
Medicine (New York, NY), Durham, NC
Dr. Michael Newman—Professor of Marine Science, School of Marine Sciences, Virginia
Institute of Marine Science, College of William & Mary, Gloucester Point, VA
Mr. Richard L. Poirot*—Environmental Analyst, Air Pollution Control Division, Department of
Environmental Conservation, Vermont Agency of Natural Resources, Waterbury, VT
Dr. Michael Rabinowitz—Geochemist, Marine Biological Laboratory, Woods Hole, MA
Dr. Joel Schwartz—Professor, Environmental Health, Harvard University School of Public
Health, Boston, MA
Dr. Frank Speizer [M.D.]*—Edward Kass Professor of Medicine, Channing Laboratory, Harvard
Medical School, Boston, MA
Dr. Ian von Lindern—Senior Scientist, TerraGraphics Environmental Engineering, Inc.,
Moscow, ID
Dr. Barbara Zielinska*—Research Professor, Division of Atmospheric Science, Desert Research
Institute, Reno, NV
SCIENCE ADVISORY BOARD STAFF
Mr. Fred Butterfield—CASAC Designated Federal Officer, 1200 Pennsylvania Avenue, N.W.,
Washington, DC, 20460, Phone: 202-343-9994, Fax: 202-233-0643 (butterfield.fred@epa.gov)
(Physical/Courier/FedEx Address: Fred A. Butterfield, III, EPA Science Advisory Board Staff
Office (Mail Code 1400F), Woodies Building, 1025 F Street, N.W., Room 3604, Washington,
DC 20004, Telephone: 202-343-9994)
*Members of the statutory Clean Air Scientific Advisory Committee (CASAC) appointed by the
U.S. EPA Administrator
II-XXX
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Abbreviations and Acronyms
aFGF
AA
AAL
AAS
ABA
ACBP
ACE
ACh
AChE
ACR
AD
ADC
ADP
AE
AEA
AFC
2-AG
A horizon
AHR
AI
ALA
ALAD
ALAS
ALAU
ALD
ALS
ALT
ALWT
AMEM
AMP
ANCOVA
ANF
Angll
ANOVA
a-fibroblast growth factor
arachidonic acid
active avoidance learning
atomic absorption spectroscopy
p-aminoisobutyric acid
Achenbach Child Behavior Profile
angiotensin converting enzyme
acetylcholine
acetylcholinesterase
acute-chronic ratio
adult
analog digital converter
adenosine diphosphate
anion exchange
TV-arachi dony 1 ethanol amine
antibody forming cells
2-arachidonylglycerol
uppermost layer of soil (litter and humus)
aryl hydrocarbon receptor
angiotensin I
5-aminolevulinic acid
5-aminolevulinic acid dehydratase
aminolevulinic acid synthetase
urinary 5-aminolevulinic acid
aldosterone
amyotrophic lateral sclerosis
alanine aminotransferase
albumin weight
Alpha Minimal Essential Medium
adenosine monophosphate
analysis of covariance
atrial natriuretic factor
angiotensin II
analysis of variance
II-xxxi
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ANP
AP
AP-1
ApoE
AQCD
Arg
AS52
ASGP-R
AST
ASV
3-AT
ATP
ATP1A2
ATPase
ATSDR
AVCD
AVS
AWQC
P
PFGF
17P-HS
3P-HSD
17P-HSDH
6p-OH-cortisol
B
BAEP
BAER
BAF
Bcell
BCFs
BCS
BDNF
BDWT
BEI
BFU-E
atrial natriuretic peptide
alkaline phosphatase
activated protein-1
apolipoprotein E
Air Quality Criteria Document
arginine
cells derived from the CHO cell line
aceyl glycoprotein receptor
aspartate aminotransferase
anode stripping voltammetry
3-aminotriazole; 3-amino triazide
adenosine triphosphate
sodium-potassium adenosine triphosphase a2
adenosine triphosphatase
Agency for Toxic Substances and Disease Research
atrioventricular conduction deficit
acid volatile sulfide
ambient water quality criteria
beta-coefficient; slope of an equation
P-fibroblast growth factor
17p-hydroxysteriod
3p-hydroxysteriod dehydrogenase
17p-hydroxysteriod dehydrogenase
6-p-hydroxycortisol
both
brainstem auditory-evoked potentials
brainstem auditory-evoked responses
bioaccumulation factor
B lymphocyte
bioconcentration factors
bovine calf serum
brain derived neurotrophic factor
body weight changes
biological exposure index
blood erythroid progenitor
II-xxxii
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BLL
BLM
BM
BMI
BDNF
BOTMP
BP
BPb
BSA
BSI
BTQ
BUN
bw, b. wt, BW
C3H10T/12
C3, C4
CA
CAS
45Ca
Ca-ATP
Ca-ATPase
CaCO3
CaEDTA
CAL
CaM
Ca-Mg-ATPase
cAMP
CaNa2 EDTA
CANTAB
CAT
CBCL
CBCL-T
CBL
CBLI
CCB
CCD
blood lead level
biotic ligand model
basement membrane
body mass index
brain-derived neurotrophic factor
Bruinicks-Oseretsky Test of Motor Proficiency
blood pressure
blood lead concentration
bovine serum albumin
Brief Symptom Inventory
Boston Teacher Questionnaire
blood urea nitrogen
body weight
mouse embryo cell line
complement proteins
chromosome aberration
cornu ammonis 3 region of hippocampus
calcium-45 radionuclide
calcium-dependent adenosine triphosphate
calcium-dependent adenosine triphosphatase
calcium carbonate
calcium disodium ethylenediaminetetraacetic acid
calcitonin
calmodulin
calcium-magnesium-dependent adenosine triphosphatase
cyclic adenosinemonophosphate
calcium disodium ethylenediaminetetraacetic acid
Cambridge Neuropsychological Testing Automated Battery
catalase; Cognitive Abilities Test
Achenbach Child Behavior Checklist
Total Behavior Problem Score
cumulative blood lead
cumulative blood lead index
cytochalasin B
charge-coupled device
-------
CCE
CCL
CCS
Cd
109/^1
Cd
CdU
CEC
CESD, CES-D
GFAP
CFU-E
CFU-GEMM
CFU-GM
cGMP
ChAT
CHD
CHO
CI
CLE-SV
CLRTAP
CLS
CMC
CMI
CNS
COH
ConA
COR
CoTx
COX-2
CP
CPT
cr
CRAC
CREB
CRF
Coordination Center for Effects
carbon tetrachloride
cosmic calf serum
coefficient of component variance of respiratory sinus
arrhythmia
cadmium
cadmium-109 radionuclide
urinary cadmium
cation exchange capacity
Center for Epidemiologic Studies Depression (scale)
glial fibrillary acidic protein
colony forming unit blood-erythroid progenitor (cell count)
colony forming unit blood-pluripotent progenitor (cell count)
blood granulocyte/macrophage progenitor (cell count)
cyclic guanosine-3',5'-monophosphate
choline acetyltransferase
coronary heart disease
Chinese hamster ovary cell line
confidence interval
competitive ligand-exchange/stripping voltammetry
Convention on Long-Range Transboundary of Air Pollution
Cincinnati Lead Study
criterion maximum concentration
cell-mediated immunity
central nervous system
cation-osmotic hemolysis
concanavalin A
cortisol
cotreatment
cyclooxygenase-2
coproporphryn
current perception threshold
creatinine
calcium release activated calcium reflux
cyclic AMP-response element binding protein
chronic renal failure
II-xxxiv
-------
CRI
CSF
CuZn-SOD
CV
CVLT
CVR.R
CYP
CYPSall
D
DA
dbcAMP
DCV
DEAE
DET
DEYO
DPS
dfs
DG
DOT
DL
DMEM
DMEM/F12
DMFS
DMPS
DMSA
DMT
DMTU
DNA
DO
DOC
DOM
DOPAc
DPASV
dp/dt
DPPD
chronic renal insufficiency
cerebrospinal fluid
copper and zinc-dependent superoxide dismutase
conduction velocity
California Verbal Learning Test
coefficient of variation of the R-R interval
cytochrome (e.g., CYP1A, CYP-2A6, CYP3A4, CYP450)
cytochrome P450 Sal 1
D-statistic
dopamine; dopaminergic
dibutyryl cyclic adenosine-3',5'-monophosphate
distribution of conduction velocities
diethylaminoethyl (chromatography)
diffusive equilibrium thin films
death of young
decayed or filled surfaces, permanent teeth
covariate-adjusted number of caries
dentate gyrus
diffusive gradient thin films
DL-statistic
Dulbecco's Minimal Essential Medium
Dulbecco's Minimal Essential Medium/Ham's F12
decayed, missing, or filled surfaces, permanent teeth
2,3-dimercaptopropane 1-sulfonate
2,3-dimercaptosuccinic acid
Donnan membrane technique
dimethylthiourea
deoxyribonucleic acid
distraction osteogenesis
dissolved organic carbon
dissolved organic carbon
3,4-dihydroxyphenylacetic acid
differential pulse anodic stripping voltammetry
rate of left ventricular isovolumetric pressure
7V-7V-diphenyl-p-phynylene-diamine
II-XXXV
-------
DR
DSA
DTC
DTK
DTPA
DTT
dw
E
E2
EBE
EBV
EC
eCB
ECG
Eco-SSL
EDS
EDTA
EEDQ
EEG
EG
EGF
EGG
EGPN
EKG
electro
EM/CM
EMEM
eNOS
EP
EPA
Epi
EPMA
EPO
EPSC
drinking water
delayed spatial alternation
diethyl dithiocarbomate complex
delayed type hypersensitivity
diethylenetriaminepentaacetic acid
dithiothreitol
dry weight
embryonic day
estradiol
early biological effect
Epstein-Barr virus
European Community
effect concentration for 50% of test population
endocannabinoid
el ectrocardi ogram
ecological soil screening level
energy dispersive spectrometers
ethylenediaminetetraacetic acid
7V-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinone
el ectroencephal ogram
egg
epidermal growth factor
effects on eggs
egg production
electrocardiogram
electrophysiological stimulation
experimental medium-to-control medium (ratio)
Eagle's Minimal Essential Medium
endothelial nitric oxide synthase
erythrocyte protoporphyrin
U.S. Environmental Protection Agency
epinephrine
electron probe microanalysis
erythropoietin
excitatory postsynaptic currents
II-xxxvi
-------
EPT
ERG
ERL
ERM
EROD
ESCA
ESRD
EST
ESTH
ET
ETOH
EXAFS
EXANES
F
F344
FAV
FBS
FCS
FCV
FD
FEF
FEP
FERT
FEVi
FGF
FI
FIAM
FMLP
fMRI
FR
FSH
FT3
FT4
FTES
macroinvertebrates from the Ephemeroptera (mayflies),
Plecoptera (stoneflies), and Trichoptera (caddisflies) group
electroretinogram; electroretinographic
effects range - low
effects range - median
ethoxyresorufin-0-deethylase
electron spectroscopy for chemical analysis
end-stage renal disease
estradiol
eggshell thinning
endothelein; essential tremor
ethyl alcohol
extended X-ray absorption fine structure
extended X-ray absorption near edge spectroscopy
F-statistic
Fischer 344 (rat)
final acute value
fetal bovine serum
fetal calf serum
final chronic value
food
forced expiratory flow
free erythrocyte protoporphyrin
fertility
forced expiratory volume in one second
fibroblast growth factor (e.g., PFGF, aFGF)
fixed interval (operant conditioning)
free ion activity model
N-formy 1 -L-methi ony 1 -L-l eucy 1 -L-pheny 1 al anine
functional magnetic resonance imaging
fixed-ratio operant conditioning
follicle stimulating hormone
free triiodothyronine
free thyroxine
free testosterone
II-xxxvii
-------
FTII
FTPLM
FURA-2
FVC
Y-GT
G
GABA
GAG
G12 CHV79
GCI
GD
GDP
GEE
GFAAS
GFR
GGT
GH
GI
GIME-VIP
GIS
GLU
GMAV
GMCV
GMP
GMPH
GnRH
GOT
GP
G6PD, G6PDH
GPEI
gp91phox
GPT
GPx
GRO
Fagan Test of Infant Intelligence
flow-through permeation liquid membranes
l-[6-amino-2-(5-carboxy-2-oxazolyl)-5-benzofuranyloxy]-2-
(2-amino-5-methylphenoxy) ethane-7V,7V,jV',jV'-tetraacetic acid
forced vital capacity
y-glutamyl transferase
gestational day
gamma aminobutyric acid
glycosaminoglycan
cells derived from the V79 cell line
General Cognitive Index
gestational day
guanosine diphosphate
generalized estimating equations
graphite furnace atomic absorption spectroscopy
glomerular filtration rate
y-glutamyl transf erase
growth hormone
gastrointestinal
gel integrated microelectrodes combined with voltammetric
in situ profiling
geographic information system
glutamate
genus mean acute value
genus mean chronic value
guanosine monophosphate
general morphology
gonadotropin releasing hormone
aspartate aminotransferase
gross productivity
glucose-6-phosphate dehydrogenase
glutathione S-transferase P enhancer element
NAD(P)H oxidase
glutamic-pyruvic transaminase
glutathione peroxidase
growth
II-xxxviii
-------
GRP78
GSD
GSH
GSIM
GSSG
GST
GSTP
GTP
GV
H+
3H
HA
Hb
HBEF
HBSS
HCG; hCG
Hct
HDL
HEP
HET
HFPLM
Hgb
HGF
HH
H-H
HHANES
H-L
HLA
H-MEM
HMP
HNO3
H2O2
HOME
HOSTE
HPLC
glucose-regulated protein 78
geometric standard deviation
reduced glutathione
gill surface interaction model
glutathione disulfide
glutathione-S-transferase
placental glutathione transferase
guanosine triphosphate
gavage
acidity
hydrogen-3 radionuclide (tritium)
humic acid; hydroxyapatite
hemoglobin
Hubbard Brook Experimenatl Forest
Hank's Balanced Salt Solution
human chorionic gonadotropin
hematocrit
high-density lipoprotein (cholesterol)
habitat evaluation procedure
Binghamton heterogeneous stock
hollow fiber permeation liquid membranes
hemoglobin
hepatocyte growth factor
hydroxylamine hydrochloride
high-high
Hispanic Health and Nutrition Examination Survey
high-low
human leukocyte antigen
minimum essential medium/nutrient mixture-F12-Ham
hexose monophosphate shunt pathway
nitric acid
hydrogen peroxide
Home Observation for Measurement of Environment
human osteosarcoma cells
high-pressure liquid chromatography
II-xxxix
-------
H3PO4
HPRT
HR
HSI
H2SO4
HSPG
Ht
HTC
hTERT
HTN
IBL
IBL x WRAT-R
ICD
ICP
ICP-AES
ICP-MS, ICPMS
ID-MS
IFN
Ig
IGF-1
IL
ILL
immuno
IMP
iNOS
i.p., IP
IPSC
IQ
IRT
ISEL
ISI
i.v., IV
IVCD
JV
phosphoric acid
hypoxanthine phosphoribosyltransferase (gene)
heart rate
habitat suitability indices
sulfuric acid
heparan sulfate proteoglycan
hematocrit
hepatoma cells
catalytic subunit of human telomerase
hypertension
integrated blood lead index
integrated blood lead index x Wide Range Achievement
Test-Revised (interaction)
International Classification of Diseases
inductively coupled plasma
inductively coupled plasma atomic emission spectroscopy
inductively coupled plasma mass spectrometry
isotope dilution mass spectrometry
interferon (e.g., IFN-y)
immunoglobulin (e.g., IgA, IgE, IgG, IgM)
insulin-like growth factor 1
interleukin (e.g., IL-1, IL-lp, IL-4, IL-6, IL-12)
incipient lethal level
immunohistochemical staining
inosine monophosphate
inducible nitric oxide synthase
intraperitoneal
inhibitory postsynaptic currents
intelligence quotient
interresponse time
in situ end labeling
interstimulus interval
intravenous
intraventricular conduction deficit
juvenile
II-xl
-------
KABC
KTEA
KXRF, K-XRF
LA
LB
LC
LD50
LDH
LDL
L-dopa
LE
LET
LH
LHRH
LN
L-NAME
LOAEL
LOEC
LOWES S
LPO
LPP
LPS
LT
LT50
LTER
LTP
LVH
liPIXE
liSXRF
MA
MA- 10
MANCOVA
MAO
Kaufman Assessment Battery for Children
Kaufman Test of Educational Achievement
K-shell X-ray fluorescence
lipoic acid
laying bird
lactation
lethal concentration at which 50% of exposed animals die
lethal concentration at which 74% of exposed animals die
lethal dose at which 50% of exposed animals die
lactate dehydrogenase
low-density lipoprotein (cholesterol)
3,4-dihydroxyphenylalanine (precursor of dopamine)
Long Evans (rat)
linear energy transfer (radiation)
luteinizing hormone
luteinizing hormone releasing hormone
lead nitrate
L-7V°-nitroarginine methyl ester
lowest-observed adverse effect level
lowest-observed-effect concentration
locally weighted scatter plot smoother
lipoperoxide
lipid peroxidation potential
lipopolysaccharide
leukotriene
time to kill 50%
Long-Term Ecological Research (sites)
long term potentiation
left ventricular hypertrophy
microfocused particle induced X-ray emission
microfocused synchrotron-based X-ray fluorescence
mature
mouse Ley dig tumor cell line
multivariate analysis of covariance
monoamine oxidase
-------
MATC
MDA
MDA-TBA
MDCK
MDI
MDRD
MEM
MG
Mg-ATPase
MiADMSA
Mi-DMSA
MK-801
MLR
MMSE
MMTV
MN
MND
MNNG
MPH
MRI
mRNA
MROD
MRS
MS
MSCA
mSQGQs
MT
MVV
MW
N, n
N/A
NAAQS
NAC
NAD
NADH
maximum acceptable threshold concentration
malondialdehyde
malondialdehyde-thiobarbituric acid
kidney epithelial cell line
Mental Development Index (score)
Modification of Diet in Renal Disease (study)
Minimal Essential Medium
microglobulin
magnesium-dependent adenosine triphosphatase
monoisamyl dimercaptosuccinic acid
mi monoisoamyl dimercaptosuccinic acid
NMD A receptor antagonist
mixed lymphocyte response
Mini-Mental State Examination
murine mammary tumor virus
micronuclei formation
motor neuron disease
7V-methyl-jV'-nitro-7V-nitrosoguanidine
morphology
magnetic resonance imaging
messenger ribonucleic acid
methoxyresorufm-O-demethylase
magnetic resonance spectroscopy
mass spectrometry
McCarthy Scales of Children's Abiltities
mean sediment quality guideline quotients
metallothionein
maximum voluntary ventilation
molecular weight (e.g., high-MW, low-MW)
number of observations
not available
National Ambient Air Quality Standards
TV-acetyl cysteine
nicotinamide adenine dinucleotide
reduced nicotinamide adenine dinucleotide
-------
NADP
NAD(P)H, NADPH
NADS
NAF
NAG
Na-K-ATPase
NAWQA
NET
NCBP
NCD
NCS
NCTB
NCV
ND
NDI
NE
NES
NF-KB
NGF
NHANES
NIOSH
NIST
NK
NMDA
NMDAR
NMR
NO
NO2
NO3
NOAEC
NOAEL
NOEC
NOEL
NOM
NORs
nicotinamide adenine dinucleotide phosphate
reduced nicotinamide adenine dinucleotide phosphate
nicotinamide adenine dinucleotide synthase
nafenopin
7V-acetyl-p-D-glucosaminidase
sodium-potassium-dependent adenosine triphosphatase
National Water-Quality Assessment
nitro blue tetrazolium
National Contaminant Biomonitoring Program
nuclear chromatin decondensation (rate)
newborn calf serum
Neurobehavioral Core Test Battery
nerve conduction velocity
non-detectable; not detected
nuclear divison index
norepinephrine
Neurobehavioral Evaluation System
nuclear transcription factor-KB
nerve growth factor
National Health and Nutrition Examination Survey
National Institute for Occupational Safety and Health
National Institute for Standards and Technology
natural killer
7V-methyl-D-aspartate
7V-methyl-D-aspartate receptor
nuclear magnetic resonance
nitric oxide
nitrogen dioxide
nitrate
no-observed-adverse-effect concentration
no-observed-adverse-effect level
no-observed-effect concentration
no-observed-effect level
natural organic matter
nucleolar organizing regions
-------
NOS
NOX
NP
NPSH
NR
NRC
NRK
NS
NSAID
NT
NTA
02
ODVP
OH
7-OH-coumarin
1,25-(OH)2-D, 1,25-(OH)2D3
24,25-(OH)2-D3
25-OH-D3
8-OHdG
O horizon
OR
OSWER
P,P
P300
P450 1A1
P450 1A2
P450CYP3all
PAD
PAH
PAI-1
PAR
Pb
204pb 206pb 207pb
21
°Pb
nitric oxide synthase; not otherwise specified
nitrogen oxides
net productivity
nonprotein sulfhydryl
not reported
National Research Council
normal rat kidney
nonsignificant
non-steroidal anti-inflammatory agent
neurotrophin
nitrilotriacetic acid
oxygen
offspring development
hydroxyl
7-hydroxy-coumarin
1,25-dihydroxyvitamin D
24,25-dihydroxyvitamin D
25-hydroxyvitamin D
8-hydroxy-2'-deoxyguanosine
forest floor
odds ratio; other oral
Office of Solid Waste and Emergency Response
probability value
event-related potential
cytochrome P450 1A1
cytochrome P450 1A2
cytochrome P450 Sal 1
peripheral arterial disease
polycyclic aromatic hydrocarbon
plasminogen activator inhibitor-1
population attributable risk
lead
lead-203 radionuclide
stable isotopes of lead-204, -206, -207, -208, respectively
lead-210 radionuclide
-------
Pb(Ac)2
PbB
PbCl2
Pb(C104)2
PBG-S
PBMC
Pb(NO3)2
PbO
PBP
PbS
PbU
PC12
PCR
PCV
PDE
PDGF
PDI
PEC
PEF
PG
PHA
Pi
PIXE
PKC
plNEpi
PMA
PMN
PMR
PN
P5N
PND
p.o.,PO
POMS
ppb
ppm
lead acetate
blood lead concentration
lead chloride
lead chlorate
porphobilinogen synthase
peripheral blood mononuclear cells
lead nitrate
lead oxides (or litharge)
progressive bulbar paresis
galena
urinary lead
pheochromocytoma cell
polymerase chain reaction
packed cell volume
phosphodiesterase
platelet-derived growth factor
Psychomotor Development Index
probable effect concentration
expiratory peak flow
prostaglandin (e.g., PGE2, PGF2); prostate gland
phytohemagglutinin A
inorganic phosphate
particle induced X-ray emission
protein kinase C
plasma norepinephrine
progressive muscular atrophy
polymorphonuclear leucocyte
proportionate mortality ratio
postnatal (day)
pyrimidine 5'-nucleotidase
postnatal day
per os (oral administration)
Profile of Mood States
parts per billion
parts per million
II-xlv
-------
PPVT-R
PRA
PRL
PROG
PRR
PRWT
PST
PTH
PTHrP
PVC
PWM
PRWT
QA/QC
Q/V
r
R2
r2
226Ra
R/ALAD
RAVLT
86Rb
RBA
RBC
RBF
RBP
RBPH
RCPM
REL
REP
RHIS
222Rn
RNA
ROS
ROS 17.2.8
RPMI 1640
Peabody Picture Vocabulary Test-Revised
plasma renin activity
prolactin
progeny counts or numbers
prevalence rate ratio
progeny weight
percent transferrin saturation
parathyroid hormone
parathyroid hormone-related protein
polyvinyl chloride
pokeweed mitogen
progeny weight
quality assurance/quality control
flux of air (Q) divided by volume of culture (V)
Pearson correlation coefficient
multiple correlation coefficient
correlation coefficient
most stable isotope of radium
ratio of ALAD activity before and after reactivation
Rey Auditory Verbal Learning Test
rubidium-86 radionuclide
relative bioavailablity
red blood cell; erythrocyte
renal blood flow
retinol binding protein
reproductive behavior
Ravens Colored Progressive Matrices
rat epithelial (cells)
reproduction
reproductive organ histology
most stable isotope of radon
ribonucleic acid
reactive oxygen species
rat osteosarcoma cell line
Roswell Park Memorial Institute basic cell culture medium
-------
RR relative risk; rate ratio
RT reaction time
RSEM resorbed embryos
RSUC reproductive success (general)
RT reproductive tissue
ESEM sum of the molar concentrations of simultaneously extracted
metal
SA7 simian adenovirus
SAB Science Advisory Board
SAM ^-adenosyl-L-methionine
SBIS-4 Stanford-Binet Intelligence Scale-4th edition
s.c., SC subcutaneous
SCAN Test for Auditory Processing Disorders
SCE selective chemical extraction; sister chromatid exchange
SCP stripping chronopotentiometry
SD Spraque-Dawley (rat); standard deviation
SDH succinic acid dehydrogenase
SDS sodium dodecyl sulfate; Symbol Digit Substitution
SE standard error; standard estimation
SEM standard error of the mean
SES socioeconomic status
sGC soluble guanylate cyclase
SH sulfhydryl
SHBG sex hormone binding globulin
SHE Syrian hamster embryo cell line
SIMS secondary ion mass spectrometry
SIR standardized incidence ratio
SLP synthetic leaching procedure
SM sexually mature
SMAV species mean acute value
SMR standardized mortality ratio
SNAP Schneider Neonatal Assessment for Primates
SNP sodium nitroprusside
SC>2 sulfur dioxide
SOD superoxide dismutase
-------
SOPR
SPCL
SPCV
SQGs
SRA
SRD
SRIF
SRM
SRT
SSADMF
SSB
SSEP
StAR
STORE!
SVC
SVRT
T
TA
TABL
T&E
TAT
TB
TEARS
TBPS
TCDD
Tcell
TCLP
TE
TEC
TEDG
TEL
TES
TEWT
TF
TG
sperm-oocyte penetration rate
sperm cell counts
sperm cell viability
sediment quality guidelines
Self Reported Antisocial Behavior scale
Self Report of Delinquent Behavior
somatostatin
Standard Reference Material
simple reaction time
Social Security Administration Death Master File
single-strand breaks
somatosensory-evoked potential
steroidogenic acute regulatory protein
STOrage and RETrieval
sensory conduction velocity
simple visual reaction time
testosterone
tail
time-averaged blood lead
threatened and endangered (species)
tyrosine aminotransferase
tibia
thiobarbituric acid-reactive species
Total Behavior Problem Score
methionine-choline-deficient diet
T lymphocyte
toxic characteristic leaching procedure
testes
threshold effect concentration
testes degeneration
tetraethyl lead
testosterone
testes weight
transferrin, translocation factor
6-thioguanine
-------
TGF
TH
232^
TLC
TNF
TOP
tPA
TPRD
TRH
TRY
TSH
TSP
TT3
TT4
TIES
TTR
TU
TWA
TX
U
235U, 238U
UCP
UDP
UNECE
Ur
USFWS
USGS
UV
V79
VA
vc
VDR
VE
VEP
VI
transforming growth factor
tyrosine hydroxylase
stable isotope of thorium-232
Treatment of Lead-exposed Children (study)
tumor necrosis factor (e.g., TNF-a)
time-of-flight
plasminogen activator
total production
thyroid releasing hormone
toxicity reference value
thyroid stimulating hormone
triple-super phosphate
total triiodothyronine
serum total thyroxine
total testosterone
transthyretin
toxic unit
time-weighted average
tromboxane (e.g., TXB2)
uriniary
uranium-234 and -238 radionuclides
urinary coproporphyrin
uridine diphosphate
United Nations Economic Commission for Europe
urinary
U.S. Fish and Wildlife Service
United States Geological Survey
ultraviolet
Chinese hamster lung cell line
Veterans Administration
vital capacity; vitamin C
vitamin D receptor
vitamin E
visual-evoked potential
variable-interval
-------
vitC
vitE
VMA
VMI
VSM
VSMC
WAIS
WDS
WHO
wise
WISC-R
WO
WRAT-R
WT
WTHBF-6
ww
XAFS
XANES
XAS
XPS
X-rays
XRD
XRF
ZAP
ZnNa2 DTPA
ZnNa2 EDTA
ZPP
vitamin C
vitamin E
vanilmandelic acid
Visual-Motor Integration
vascular smooth muscle (cells)
vascular smooth muscle cells
Wechsler Adult Intelligence Scale
wavelength dispersive spectrometers
World Health Organization
Wechsler Intelligence Scale for Children
Wechsler Intelligence Scale for Children-Revised
whole organism
Wide Range Achievement Test-Revised
wild type
human liver cell line
wet weight
X-ray absorption fine structure
X-ray absorption near edge spectroscopy
X-ray absorption spectroscopy
X-ray photoelectron spectroscopy
synchrotron radiation
X-ray diffraction
X-ray fluorescence
correction in reference to three components of matrix effects:
atomic number (Z), absorption (A), and fluorescence (F)
zinc disodium diethylenetriaminepentaacetic acid
zinc disodium ethylenediaminetetraacetic acid
zinc protoporphyrin
II-l
-------
AX5. CHAPTER 5 ANNEX
ANNEX TABLES AX5-2
AX5-1
-------
Table AX5-2.1. Effect of Lead on Erythrocyte Morphology, Mobility, and Other Miscellaneous Parameters
X
to
Dose and Route of
Exposure Duration Species
Pb nitrate (a) Pb recovery Erythrocyte cell lysates from
0-100 uM, studies, humans
Free Pb2+ 10 min
0-20 uM, (b) Relationship
In vitro of free Pb2+ to
added Pb,
20 min
Pb nitrate 1 h Human erythrocytes
1.5 mM
In vitro
10 uM Pb, 20 min Erythrocyte ghosts and
as Pb acetate, unsealed erythrocytes
In vitro
100 ug/dL Pb, 1 h Human erythrocytes
10 mg/dL, Pb,
In vitro
24 h
2 uM Pb acetate 0-1 h MDCK Kidney epithelial cell
2 uM Pb line, In vitro
0-2 h Human erythrocytes, in vitro
10or20mMPb 5 wks Albino rats
acetate, i.p. once a
week (100 or
200 umoles)/ kg b.wt.
Blood lead Effect
— Uptake and transport of Pb in erythrocyte and across erythrocyte cell
membrane under the influence of varying buffers and ions.
a. Pb can cross the membrane passively in either direction.
Influx and efflux show similar properties
b. Passive transport of Pb is strongly stimulated by HCO3~
(bicarbonate)
c. Pb uptake is unaffected by varying the external concentrations of
Na+, K+, and Ca2+
d. In RBC, Pb binds mainly to hemoglobin. The ratio of bound Pb
to free Pb + in the cytosol is estimated 6000: 1
— Pb uptake and transport are studied in resealed erythrocyte ghosts.
a. Transport of Pb across erythrocyte membranes is passive
b. 90% of Pb uptake by erythrocytes is inhibited by drugs that block
anion transport, indicating the involvement of anion exchanges
c. Pb transport depends upon the presence of a second anion. In the
presence of HCO3~, the rate is stimulated in the order of C1O4~
-------
Table AX5-2.1 (cont'd). Effect of Lead on Erythrocyte Morphology, Mobility, and Other Miscellaneous Parameters
X
Dose and Route of
Exposure Duration
20 mM Pb acetate, 5 wks
i.p. once a week
(200 (imoles/kg b.wt)
200 uM of Pb acetate, Once a week for
i.p. 5 wks
Pb, i.p. 20 mg/ kg 14 consecutive
b.wt. days
1 uM Pb nitrate 1 h
1 uM Pb nitrate, 1 h
In vitro
6 and 12 mo
0. 1-200 pM, 1-6 h
Pb nitrate in the
reaction buffer
0. 1-10 uMPb ions 24 h
from 10 mM
Pb(NO3)2 solution,
In vitro
Species
Male
Wistar Albino rats
Rat
Male
Albino rat
Erythrocytes from Pb-exposed
healthy humans
Erythrocytes from healthy
human volunteers
Erythrocytes from Pb-exposed
rats
In vitro, human erythrocytes
Erythrocytes from healthy
human volunteers
Blood lead Effect
Control: Exposure to Pb significantly decreased RBC membrane sialic acid
1-12 jig/100 mL content, erythrocyte survival, hemoglobin, and hematocrit. This was
Exposed: evident to a minor extent below blood Pb levels 100 ug/100 mL and
100-800 ng/dL was generally present from 100 ug/100 mL and higher.
0-600 ug/dL Pb exposure significantly decreases RBC count, Hb values,
hematocrit, mean corpuscular volume, and mean corpuscular
hemoglobin, decreases erythrocyte mobility, membrane sialic acid
content, and deformability.
Acetyl choline esterase (AchE), NADH dehydrogenase, and Na+-K+
ATPase activities in rat erythrocyte membranes were inhibited by Pb
exposure. Erythrocyte membrane sialic acid, hexose, hexosamine
were inhibited by Pb exposure. Membrane phospholipids and
cholesterol were increased.
Controls: Pb exposure in healthy human RBC membranes resulted in increased
8.3 ug/dL levels of arachidonic acid (AA). The increase in AA correlated in a
Exposed: dose dependent manner with elevation in Pb and with serum iron.
70. 5 ug/dL On the other hand, a negative correlation was found between Aa and
serum calcium. It is inferred that substitution of Pb to calcium,
which is essential for the release of phospholipase A2 for AA release
may be the reason for increased RBC membrane AA.
— Pb inhibits Gordos effect in human erythrocytes; electron spin
labeling studies indicated cell shrinkage and decreased volume.
Cation-osmotic hemolysis (COH) in 12 mo Pb-exposed rats was
lower in the areas of lower ionic strength on erythrocyte membranes.
— Pb crosses the erythrocyte membrane by the anion exchanger and
can also leave erythrocytes by a vanadate-sensitive pathway,
identified with the calcium pump. The high ratio of erythrocyte to
plasma Pb seen in vivo appeared to be due to the presence of a labile
Pb2+- binding component present in erythrocyte cytoplasm.
— Pb activates erythrocyte K+ channels, Ca + sensitive erythrocyte
Scramblase, triggers Phosphatidyl serine receptors and result in cell
shrinkage and decreased life span.
Authors
Terayama and
Muratsuga(1988)
Terayama (1993)
Jehan and Motlag
(1995)
Osterode and Ulberth
(2000)
Eriksson and Beving
(1993)
Mojzis and Nistiar
(2001)
Simons (1993a)
Kempe et al. (2005)
-------
Table AX5-2.1 (cont'd). Effect of Lead on Erythrocyte Morphology, Mobility, and Other Miscellaneous Parameters
X
Dose and Route of
Exposure
20 uM Pb ion,
In vitro
20 uM Pb ions,
In vitro
Erythrocytes from
Pb-exposed workers
24-45 yr old white
males
O.lmMPb final
concentration,
In vitro
1-10 uM Pb acetate,
In vitro
0-1200 nM Pb,
In vitro
Duration
2 min-2 h
Ih
Duration of
exposure not
given. RBCs
were isolated.
Experiments
were performed
in ghosts and
resealed
membranes
Ih
3h
Ih
Species
Erythrocytes from human
umbilical cord
Human umbilical cord
erythrocytes
Humans
Erythrocytes from healthy
humans
Erythrocytes from healthy
humans
Erythrocytes from healthy
humans
Blood lead Effect
— Pb attenuates prolytic effect on neonatal erythrocytes in iso-or
hypotonic low ionic strength media.
Hemolytic activity of Organo Pbs increases with their
hydrophobicity: triethyl Pb chloride < tri-n-propyl Pb chloride
< tributyl tin chloride.
— Pb ions increase the resistance to lysis in media of diminishing
tonicity. These changes might be mediated by changes in membrane
structure.
1.17-1.54 uM Increased blood Pb in exposed workers was associated with a
significant decrease in the average micro viscosity of resealed and
unsealed erythrocyte membranes. Alterations in the microviscosity
of the lipid regions of the hydrophobic core of the erythrocyte
membrane bilayer and in the phospholipid composition of the
membrane may be defects that contribute to the clinical and
biochemical alterations/effects.
— Pb particles adhere to the external and internal surfaces of the human
erythrocyte membrane and disturb the lamellar organization of lipid
bilayers.
— Low concentrations of Pb alter the physicochemical properties of
proteins and lipids in erythrocyte membranes.
— Significant increase in the phosphorylation of membrane cytoskeletal
proteins in Pb treated human erythrocytes at concentrations above
Authors
Serrani et al. (1997)
Kleszcynska et al.
(1997)
Corchsetal. (2001)
Cooketal. (1987)
Suwalsky et al. (2003)
Slobozhanina et al.
(2005)
Belloni-Olivi et al.
(1996)
100 nM mediated by enhanced PKC activity.
-------
Table AX5-2.1 (cont'd). Effect of Lead on Erythrocyte Morphology, Mobility, and Other Miscellaneous Parameters
>
X
Dose and Route of
Exposure
—
Duration
— a.
b.
c.
Species
24 adult healthy controls
(humans)
12 patients with Pb
poisoning (plumbism)
symptoms (Pb controls)
Patients with chronic renal
failure (CRF)
Divided into:
Occupational,
Human exposure
1.
2.
— a.
b.
Normal urinary blood Pb
levels
High urinary blood Pb
levels
28 male workers in a Pb
refining factory
Controls
Blood lead
Controls:
-17.1 ug/dL
Pb controls:
80.5 ug/dL
CRF -1:
18.4 ug/dL
CRF -2:
18.0 ug/dL
Urinary Pb CRF 1:
-322ug/72h
CRF 2:
1785 ug/72 h
Exposed:
-35.97 ug/lOOg
Controls:
5.23 ug/100 g
Effect
Increased erythrocyte Zn protoporphyrin to free protoporphyrin
ratio in Pb controls and remained in the normal range in CRF
patients. CRF patients showed minor abnormalities of erythrocyte
heme metabolism, such as low ALAD activity.
SDS polyacrylamide electrophoresis for erythrocyte membrane
proteins showed bands at 3 and 4. 1, that significantly decreased
while bands 2.3, 6, and 7 significantly increased in the Pb workers
compared with controls.
Authors
Fontanellas et al.
(2002)
Fukumoto et al.
(1983)
RBC—Red blood cells; Hb—Hemoglobin; NADH—Nicotinamide adenine dinucleotide dehydrogenase; PKC—Protein kinase C; AchE—Acetyl choline esterase
-------
Table AX5-2.2. Lead, Erythrocyte Heme Enzymes, and Other Parameters
X
Dose and Route of
Exposure Duration
Dietary, 35 days
0-100 ug/g dry wt. of
the diet
Pb acetate, oral 3 or 1 1 wks
gavage, 1.5mg/kg
b.wt, Pb acetate
20 ng/mL as Pb 5 wks
acetate in drinking
water
17 uM Me/kg Pb 5 days
acetate, Per OS
1.5 mgPb/kg body 8 yrs
wt, oral dose
Occupational 1 1-22 yrs
exposure
Species
Adult male Zebra finches
Red-tailed Hawks
Female Wistar Albino rats
Female
Rabbits
Cynomolgus Monkey,
in vitro
Dogs from urban and rural
areas of Greece
Human erythrocytes from
exposed populations
Blood lead Effect
0-1.5 |ig/mL Significant negative correlation was observed between blood-Pb
concentration and log ALAD activity. RBC ALAD activity ratio is
a sensitive indicator of dietary Pb concentration regardless of the
mode of exposure.
0.195- Erythrocyte phorphobilinogen synthetase was depressed
0.752 ug/dL significantly with in the 1st wk of treatment. Rapid but brief
increase in free protoporphyrin. Hematocrit, erythrocyte count, Hb
were all decreased and blood viscosity increased in exposed group.
37.8 ug/dL Pb exposure decreases hematocrit, hemoglobin, and the number of
erythrocytes and enhances blood viscosity.
— Pb causes a significant decrease in blood ALAD activity, increases
free erythrocyte protoporphyrins, increases aminolevulinic acid
and coporphyrin excretion in urine.
— Kinetic analyses of erythrocyte 6- aminolevulinic acid revealed
differences in PH optimum and Michaelis constants with Pb
exposure. The ALAD enzyme kinetics of Pb exposed monkeys
and humans are similar.
326, 97-68 ug/L Significant negative correlation existed between blood-Pb levels
and ALAD activity. 807-992 umol/PBG/LRBC/h is established as
the normal erythrocyte ALAD range for dogs.
1.39-1.42 umol/1 Liquid chromatography with inductively coupled plasma
spectrometry had revealed ALAD to be the principle Pb binding
Authors
Scheuhammer et al.
(1987)
Redigetal. (1991)
Toplan et al. (2004)
Zareba and
Chmelnicka(1992)
Dorward and
Yagminas (1994)
Polizopoulou et al.
(1994)
Bergdahl et al. (1997)
protein. The percentage of Pb bound to ALAD was influenced by
a common polymorphism in the ALAD gene.
0-20 mg Pb liter -1
29 days
Juvenile Rainbow trout
erythrocytes
Significant decreases in the erythrocyte ALAD activity after a 29- Burden et al. (1998)
days exposure to 121 and 201 mg Pb liter -1.
-------
Table AX5-2.2 (cont'd). Lead, Erythrocyte Heme Enzymes, and Other Parameters
X
Dose and Route of
Exposure
Pb acetate 160 mg/L
in water
1.46 umol/liter,
In vitro
Pb 0.34 uM/L-
1.17uM/L,
subcutaneous
injection
0-60 pM Pb ion,
In vitro
200-500 ppm Pb in
drinking water
0. 1-100 uMPb ion,
In vitro
20-5 ug/kg body wt
1 mg/ kg body wt
Duration Species Blood lead
8 wks Wistar rats > 20 - > 40 ug/dL
— Fish from regions close to —
the smelters and down stream
48 h Human whole blood —
erythrocyte hemolysates,
normal and Pb intoxicated
individuals
1 h Male albino New Zealand —
rabbits
20 min Human erythrocyte lysates —
14 or 30 days Male ddY mice 24-5 1 ug/100 mL
5 min Human erythrocyte ghosts —
Pregnancy Erythrocytes from Sprague- —
through lactation Dawley rats
Effect
Pb increases blood and liver Pb, erythrocyte porphyrin content,
hypoactivity of both hepatocytic and erythrocytic ALAD.
Smelter site fish had elevated Pb concentrations, decreased ALAD
activity and species differences in this inhibitory activity were
apparent that could be attributed to Zn levels.
The effects of various divalent cations on erythrocyte
porphobilinogen are concentration and PH dependent. Zn restores
the Pb inhibited activity.
Pb causes the most inhibition and Zn activation of rabbit Erythrocyte
porphobilinogen activity. Cu2+, Cd2+, and Hg2+ are intermediary.
Each divalent ion has a characteristic effect on the PH- activity
relationship of PBG-S.
Human erythrocyte lysate porphobilinogen activity is increased by
Zn2+ with a Km of 1.6 pM and inhibited by Pb with a Ki of 0.07 pM,
Pb reduced the affinity for the substrate 5- aminolevulinate, non-
competitively.
Pb inhibits erythrocyte and bone marrow P5'N activity. Erythrocyte
ALAD activity was inhibited by 90%. Elevation of Urinary
excretion of ALA with no change in erythrocyte protoporphyrin and
urinary co porphyrin as against in the Pb exposed humans indicates
that protoporphyrin metabolism might be more resistant to Pb in
mice than humans.
Under normal incubation conditions Pb inhibits, Ca2+ -Mg2+ ATPase
with an IC50 of 6.0uM. Pb inhibits Ca2+- Mg2+ ATPase related to
sulphahydryl groups above 1.0 uM Pb and by direct action of Pb
upon Calmodulin below 1.0 uM.
Na2+- K+- ATPase and Ca2+- Mg+- ATPase of erythrocyte membranes
from Pb-depleted animals did not change in PO generation as
Authors
Santos et al. (1999)
Schmitt et al. (2002)
Farant and Wigfield
(1987)
Farant and Wigfield
(1990)
Simons (1995)
Tomokuni et al.
(1989)
Mas-Oliva(1989)
Ederetal. (1990)
compared to 1 mg/kg b.wt Pb animals, where as in Fl generation Pb
depleted rats showed reduced activity.
-------
Table AX5-2.2 (cont'd). Lead, Erythrocyte Heme Enzymes, and Other Parameters
Dose and Route of
Exposure
Duration
Species
Blood lead
Effect
Authors
20 mg Pb acetate/kg
b.wt, i.p,
In vivo
14 days
Male Albino rats
erythrocytes
Pb significantly decreases erythrocyte membrane acetyl choline esterase, Jehan and Motlag
NADH dehydrogenase, membrane sialic acid, hexose, and hexosamine. (1995)
Pb ions inhibit aerobic glycolysis and diminish ATP level in human
erythrocytes in vitro. Magnesium partly abolishes these effects by
stimulating Magnesium dependent enzymes. Effect is seen both by
direct addition of Pb acetate to erythrocyte ghosts as well as in the ghosts
obtained after preincubation of erythrocytes with Pb acetate. Ca2+, Mg2+
ATPase is less sensitive and Mg ATPase is practically insensitive to Pb
under these conditions.
Grabowska and
Guminska(1996)
X
(Si
I
oo
10-200 ug/dLPbions
(Pb acetate),
In vitro
Pb acetate through
water or i.p. 1 or
2 mg/Kg b.wt.
20 h
Human umbilical cord
erythrocytes
Every 4th day Wistar rats
for 1 mo
— Pb significantly decreased the concentration of ATP, ADP, AMP,
adenosine, GTP, GDP, GMP, Guanosine, IMP, inosine, hypoxanthine,
NAD and NADP concentrations.
1.51— The concentrations of adenosine tri phosphate (ATP), Guanosine
35.31 ug/dL triphosphate (GTP), Nicotinamide adenine dinucleotide NAD+,
nicotinamide adenine dinucleotide phosphate NADP+ adenylate and
Guanylate (AEC and GEC) were significantly reduced in erythrocytes of
exposed animals. Results indicate Pb ions disrupt erythrocyte energy
pathway.
Baranowska-Bosiacka
and Hlynczak (2003)
Baranowska-Bosiacka
and Hlynczak (2004)
ALAD — Aminolevulinic acid; Cu2+—Copper; Cd2+—Cadmium; Hg2+—Mercury; PBG-S Porphobilinogen synthetase; Zn—Zinc; ATP—Adenosine triphosphate; ADP—Adenosine diphosphate;
AMP—Adenosine monophosphate; GTP—Guanosine tri phosphate; GDP—Guanosine diphosphate; GMP—Guanosine monophosphate; IMP—Inosine monophosphate; NAD—Nicotinamide
adenine dinucleotide; NADP—Nicotinamide adenine dinucleotide phosphate.
-------
X
Table AX5-2.3. Lead Binding and Transport in Human Erythrocytes
Dose and Route of
Exposure Duration Species Blood lead
Effect
Authors
0-60 pM Pb ion,
In vitro
20min
Human erythrocyte lysates
Human erythrocyte lysate porphobilinogen activity is increased by Zn + Simons (1995)
with a Km of 1.6 pM and inhibited by Pb with a Ki of 0.07 pM, Pb
reduced the affinity for the substrate 5- aminolevulinate, non-
competitively.
Zn—Zinc
-------
Table AX5-2.4. Lead Effects on Hematological Parameters
Dose and Route of
Exposure Duration
Species
Blood lead
Effect
Authors
4-6 mg/Kg b.wt, i.p., 15 and 30 days
daily
Intact and splenctamized rats
Pb increases urinary 6-amino levulinic acid (ALA) excretion, Gautam and
depletion in RBC hemoglobin content, and more number of Chowdhury (1987)
reticulocytes in peripheral blood, and results in accumulation of
immature erythrocytes both in intact and splenctomized rats.
0.82mgPb/kg 3orllwks
b.wt./d, oral gavage
Red-tailed hawks erythrocytes
0.195-0.375 mg/mL Activity of porphobilinogen synthase/ALAD was depressed
significantly in Pb exposed rats and did not return to normal
values until 5 wks after the termination of the treatment. A rapid
and relatively brief increase in erythrocyte free proto porphyrin
and a slower, prolonged increase in Zn complex.
Redigetal. (1991)
>
X
17 uM Me/Kg b.wt
Pb acetate or 3.5 mg
of Pb/kg body wt, i.p
17 uM Me/Kg b.wt
Pb acetate or 3.5 mg
of Pb/ kg body wt, i.p.
or per OS 17.5 mg/kg
b.wt single injection
5 days
5 days i.p.
Female Rabbits
Female Rabbits
Pb causes a significant inhibition of ALAD in the blood , Zareba and
increases free erythrocyte protoporphyrin, and urinary excretion Chmielnicka (1992)
of Aminolevulinic acid and coporphyrin.
Pb induced ALAS activity in liver and kidney, both after i.p and Chmielnicka et al.
p.o. administration; i.p. administration of Pb also induced kidney (1994)
heme oxygen levels.
Cu deficient 1 mg
Cu/Kg
Marginal deficient
2 mg/kg
Control 5 mg Cu/Kg
High Zn 60 mg/kg.
4 wks
Rat
Moderately high Zn in the diet reduces plasma copper but not
plasma ceruloplasmin.
Does not affect the recovery of plasma Cu or activity after oral
copper sulphate in Cu deficient diets.
Does not influence RBC Super oxide dismutase activity.
Panemangalore and
Bebe (1996)
0.02-40 ppm Pb, 90 days Male and female Swiss mice 0.7-13.0 ug/dL Increased RBC number and increased hemoglobin and decreased lavicoli et al. (2003)
dietary hematocrit up on Pb exposure.
20 ug/mL, Pb acetate 5 wks
in drinking water
Female Wistar Albino rats 37.8 ug/dL
Erythrocyte count, hematocrit and hemoglobin were all decreased Toplan et al. (2004)
and blood viscosity increased in Pb exposed workers.
-------
Table AX5-2.4 (cont'd). Lead Effects on Hematological Parameters
>
X
Dose and Route of
Exposure
Erythrocytes from
humans of
occupational Pb
exposure and controls
In vivo and in vitro
In vivo; exposure
In vitro assays on
erythrocytes from
exposed populations
Duration Species
— Male Pb workers and
13 normal volunteers
— 1 . Workers exposed to
manganese (Mn) and
2. Workers exposed to Pb
without clinical
manifestations of
intoxication
Blood lead Effect
Range 20.6- Nicotinamide adenine dinucleotide synthetase activity in the Pb workers
71.3 ug/dL ranged from 0.08 to 1.1 umol/h per g of hemoglobin. 50% of enzyme
inhibition was observed at 40 ug/dL. Aminolevulinic acid dehydratase
activity decreased rapidly and reached a plateau at Pb-B levels 40-60
ug/dL. 50% of enzyme activity inhibition was observed at 20 ug/dL.
— Erythrocyte concentrations of adenyl nucleotides (ADP and ATP) were
elevated in both groups of workers and that of AMP in Pb-exposed
workers. The ratio of ATP/ADP significantly increased in Pb-exposed
workers.
Authors
Moritaetal. (1997)
Nikolova and
Kavaldzhieva et al.
(1991)
ALA—Aminolevulinic acid; ALAS—Aminolevulinic acid synthetase; ALAD—Aminolevulinic acid dehydratase, RBC—Red blood cells.
-------
Table AX5-2.5. Lead Interactions with Calcium Potassium in Erythrocytes
>
X
Dose and Route of
exposure Duration Species
0-325 uM, Pb nitrate, 0-60 min In vitro
In vitro
0 uM-5 mM Pb, 0-100 min Human erythrocyte
In vitro hemolysates
1-4 uM Pb acetate, 0-30 min Rabbit reticulocytes
In vitro
1-50 uM Pb ion, 20 min Marine fish erythrocytes
In vitro
Blood lead Effect
— Pb modifies the threshold sensitivity of individual K+channels to Ca +
with a biphasic time course. The increase of Pb concentration increased
the extent of the initial inhibition and decreased the duration. The
inhibitory effect was not observed when addition of Calcium preceded
the addition of Pb. Pb decreased the rate of uptake of 86Rb.
— Pb and Ca transport was carried out by a passive transport system with
two kinetic components (Michaelis- Menten and Hill) Pb and Ca were
capable of inhibiting the transport of the other metals in a non-
competitive way.
— Pb at low concentrations inhibits the uptake of Fe (II) into all three
(heme, cytosolic and stromal) fractions. The saturable components were
inhibited at lower concentrations of Pb than the non- saturable
components.
— Pb activates Ca2+ activated potassium channels. Treatment of
erythrocytes with 1-2 uM Pb led to a minor intra cellular K loss and at
Authors
Alvarez et al. (1986)
Calderon- S alinas
etal. (1999b)
Qian and Morgan
etal. (1990)
Silkinetal. (2001)
Pb depleted rats
Pb concentration
<20 ug/kg
Diet, oral
Pb controls
200,800 ug/kg Pb2+ in
the form of supra pure
Pb acetate. Diet, oral
Intact or erythrocyte
ghosts
0-100 uM Pb ion or
Pb nitrate in the
reaction mix,
In vitro
Gestation
through to
15 days of
lactation
Sprague-Dawley rats
Pb concentrations of 20-50 uM 70% of potassium was lost.
The concentration of CA2+ ions in erythrocytes of Pb-depleted rats was
elevated in FI generation, without changes in P0 generation. The
elevation observed in depleted rats could be because of a reduction in
CA2+-Mg2+ ATPase.
Loipfiihrer et al.
(1993)
10 min
Healthy human erythrocytes
Modulation of CA2+-activatable K+ permeability was compared with
modulation of a membrane-bound oxidoreductase activity in human
erythrocytes. Pb, anitrion, and menadione had parallel effects on the
channel protein and the enzyme. The results demonstrate that the K+
channel and the enzyme are distinct membrane proteins and the enzyme
activity may influence channel gating.
Fehlau etal. (1989)
Pb—Lead; K+—Potassium; Na2+- K+ ATPase—sodium potassium ATPase; Ca2+- Mg2+ ATPase—Calcium, Magnesium ATPase.
-------
X
Table AX5-2.6. Lead, Heme, and Cytochrome P-450
Dose and Route of
exposure
Duration
Species
Blood lead
Effect
Authors
0-75 mg of Pb2+/Kg b. 0-30 h
wt. i.p., Single
injection
C57 BL/6 male mice
Pb causes an increase in 6-amino levulinic acid levels in plasma and a
decrease in the heme saturation of hepatic tryptophan -2,3 dioxygenase.
P-450- dependent activities, EROD and O-dealkylation of
alkoxyresorufins decreased progressively. Pb exposure decreased
mRNA levels of the P450 CYp3al 1. The decrease in P450 transcription
was a mechanism dependent on heme by inhibition of heme synthesis
and also by a mechanism independent of heme in which Pb decreases P-
450 transcription.
Joveretal. (1996)
EROD—Ethoxy resorufin-O-dealkylase.
CYp3al 1—Cytochrome P-450 Sail.
-------
Table AX5-2.7. Lead, Erythrocyte Lipid Peroxidation, and Antioxidant Defense
X
Dose and Route of
exposure
7.5 mg of Pb acetate
or4.09mgofPb
Kg"1 b.wt, oral
5.46 mg Pb as Pb
acetate, oral
10 mg/kg b.wt Pb
acetate, intra
muscular, daily
Pre treatment with
melatonin
A. ALA 40 mg/kg
b.wt every other day
and/or
B. Melatonin
10 mg/kg
Pb acetate 0.2%, in
drinking water,
followed by
individual or
combined treatment of
lipoic acid (25 mg/Kg
b.wt and DMSA
20 mg/kg b.wt, i.p.)
6-Aminolevulinic
acid, 1-5 mM, In vitro
Duration Species Blood lead
28 days, Erythrocytes from male Calves 0.1-1. 6 ppm
multiple
analyses at day
7, 14, 21, and 28
14 days, Erythrocytes from female goats 0.09-1. 12 ppm
multiple
analyses at day
0, 7, and 14
7 days Rat —
Every other day Male Sprague- Dawley rats —
3 times daily for
2 wks
5 wks Male Albino rats 97.5 ug/dL
10 days CHO cells —
Effect
Pb exposure significantly reduced erythrocyte super oxide dismutase
activity until day 21 followed by a marginal increase by day 28. Total,
protein-bound and non protein- bound -SH content of erythrocytes
declined.
Pb exposure caused a significant increase of erythrocytic GPx, SOD and
CAT activities, total thiol groups and total antioxidant status.
Pb significantly decreased heme synthesis, decreased Hb, decreased liver
6- ALAS and erythrocyte ALAD. Markedly elevates hepatic lipid
peroxidation, reduced anti oxidant enzymes such as total sulphahydryl
groups and Glutathione. Pre Treatment with melatonin reduced the
inhibitory effect of Pb on both enzymatic and non enzymatic
antioxidants and reduced the iron deficiency caused by Pb.
Melatonin effectively protects nuclear DNA and lipids in rat lung and
spleen against the oxidative damage caused by the carcinogen ALA.
Pb exposure results in decreased blood hemoglobin, hematocrit,
enhanced erythrocyte membrane lipid peroxidation, decline in the
activities of erythrocyte membrane Na+-K+ ATPase, Ca2+ ATPase, and
Mg2+ ATPase. Treatment with lipoic acid and/or DMSA reduced the Pb
induced adverse changes in the biochemical parameters.
6- Aminolevulinic acid treatment induces oxidative stress in Chinese
hamster ovary cells by inducing Glutathione, Glutathione disulphide,
Malandialdehyde equivalents, and Catalase. N-acetyl cysteine
administration reverses the decrease in cell survival and colony
formation induced by 6- ALA.
Authors
Patra and Swarup
et al. (2000)
Mousa et al. (2002)
El- Missiry (2000)
Karbownik et al.
(2000)
Sivaprasad et al.
(2003)
Nealetal. (1997)
SOD—Super oxide dismutase; CAT—Catalase; ALAS—Aminolevulinic acid synthatase, ALAD—Aminolevulinic acid dehydratase; ALA—Aminolevulinic acid; GPX—Glutathione peroxidase
-------
ANNEX TABLES AX5-3
AX5-15
-------
Table AX5-3.1. Summary of Key Studies on Neurochemical Alterations
Subject
Rat
PND 16-18
Rat
PND 50
Rat
PND 7, 14,21,
28, and 50
Rat
PND 21
X
1
Oi
Adult rat
Adult rat
Embryonic rat
Exposure Protocol
Hippocampal cultures
1500ppmPb(Ac)2
chow 10 days before breeding and
maintained to sacrifice
1500ppmPb(Ac)2
chow 10 days before breeding and
maintained to sacrifice
750 ppm Pb(Ac)2
chow from GD 0 to PND 21
Cultured PC 12 cells
Water— 0. 1-1 .0% Pb(Ac)2
fromGD 15 to adult
Water— 0. 1-1 .0% Pb(Ac)2
fromGD 15 to adult
Cultured PC 12 cells
Hippocampal neurons
Peak Blood Pb or
[Pb] used
0.1 and 1.0 uM
PbCl2
3 1.9 ug/dL
—
46.5 ug/dL
0.03-10 uM
Pb(N03)2
61.8ug/100mL
117.6ug/100mL
0.53 uMPb(Ac)2
lOOfM-lOOnM
Observed Effects
Pb blockage of IPSCs were partially reversible while EPSCs were not.
Decreases the NR1 subunit splice variant mRNA in hippocampus.
Alters NMDAR subtypes and reduces CREB phosphorylation.
Increased expression of nicotinic receptors.
Pb acts as a high affinity substitute for calcium in catecholamine
release.
Hippocampal GLU and GABA release exhibits biphasic effects from
chronic Pb.
NMDA receptor function is upregulated.
PKC is involved in TH upregulation but not downregulation of ChAT.
Decreases [Ca2+]i and increases Ca2+ efflux by a calmodulin-dependent
mechanism.
Reference
Braga et al. (2004)
Guilarte and
McGlothan (2003)
Toscano et al. (2002)
Jett et al. (2002)
Westerink and
Vijverberg (2002)
Lasley and Gilbert
(2002)
Lasley etal. (2001)
Tian et al. (2000)
Ferguson et al.
(2000)
Rat
750orl500ppmPb(Ac)2
chow from 10 days pre-mating to
PND 14, 21, and 28
61.1 ug/dL
Dose-response effect between level of Pb and expression of NR1 gene. Guilarte et al. (2000)
Cultured PC 12 cells
5-20 uM Pb(Ac)2 Induces expression of immediate early genes but requires PKC.
Kim et al. (2000)
-------
Table AX5-3.1 (cont'd). Summary of Key Studies on Neurochemical Alterations
X
Subject
Rat
PND 50
Adult rat
Adult rat
PND 2
Rat
Rat
PND 17
Rat
PND 7, 14,21,
28
Rat
PND 7, 14,21,
28
Rat
PND 22-adult
Rat
PND 28 56,
112
Exposure Protocol
750orl500ppmPb(Ac)2
chow from 10 days pre-mating to
PND 50
Calcineurin in mixture
Cerebrocortical membranes
0.2% Pb(Ac)2
in water and chow
Cultured hippocampal neurons
Cultured hippocampal neurons
750 ppm Pb(Ac)2
chow from 14 days pre-mating to
experimental use
750 ppm Pb(Ac)2
chow from 14 days pre-mating to
experimental use
Water— 0.2% Pb(Ac)2
from GDI 6 to PND 21
Water— 1000 ppm Pb(Ac)2
from GD 4-use
Peak Blood Pb or
[Pb] used
31.9ng/dL
1 0-2000 pM
Pb(NO3)2
0.01^1 nM
free Pb(Ac)2
52.9 ng/100 mL
0.01-10 nMPbCl2
0.1-10nMPbCl2
59.87 |ig/dL
59.87 ng/dL
—
39.6 ng/dL
Observed Effects
Reductions in NMDAR receptors result in deficits in LTP and spatial
learning.
Has a stimulatory (low) and inhibitory (high) effect on calcineurin.
Pb binds to the NMDA receptor channel in a site different from zinc.
GLU and GABA release are inhibited independent of Pb exposure
period.
Inhibits glutamatergic and GABAergic transmission via calcium
channel.
Increases tetrodotoxin- insensitive spontaneous release of GLU and
GABA.
NMDAR-2A subunit protein expression is reduced in the
hippocampus.
Alters the levels of NMDA receptor subunits mRNA in hippocampus.
Induces loss of septohippocampal cholinergic projection neurons in
neonates lasting into young adulthood.
Significant increase in [ HJMK-801 binding after chronic exposure.
Reference
Nihei et al. (2000)
Kem and Audesirk
(2000)
Lasley and Gilbert
(1999)
Lasley etal. (1999)
Bragaetal. (1999a)
Bragaetal. (1999b)
Nihei and Guilarte
(1999)
Guilarte and
McGlothan(1998)
Bourjeily and
Suszkiw(1997)
Ma etal. (1997)
-------
Table AX5-3.1 (cont'd). Summary of Key Studies on Neurochemical Alterations
Subject
Rat
PND21-adult
Adult rat
Rat
4 mo
Rat
PND 111
X
1
oo
Rat
Rat
PND 14 or 56
Rat
Exposure Protocol
50 or 150ppmPb(Ac)2
water for 2 wks-8 mo
Water— 0.2% Pb(Ac)2
from PND 0-adult
Water— 0.2% Pb(Ac)2
from GDI 6 to PND 28
Water at 50 ppm Pb(Ac)2
for 90 days; start at PND 21
Cultured bovine chromaffin cells
Homogenized cortex
Cultured bovine chromaffin cells
Neuronal membranes
Cortical synaptosomes
Peak Blood Pb or
[Pb] used
28.0 ug/dL
37.2 ug/100 mL
22.0 ug/dL
18 ug/dL
Variable kind and
concentration
Ranging Pb(Ac)2
Variable kind and
concentration
Chow containing
750 ppm Pb(Ac)2
1-50 nM free Pb
orl uMPb(NO3)2
Observed Effects
Differential effects in [ HJMK-801 binding with dopamine and D]
agonists.
Presynaptic glutamatergic function in dentate gyrus is diminished.
Developmental Pb results in long-lasting hippocampal cholinergic
deficit.
Decreases in vivo release of dopamine in the nucleus accumbens.
Exerts dual stimulatory and inhibitory effects on adrenal PKC.
Pb activates PKC in the range of 10~u to 10~8 M.
Pb and calcium activate the exocytotic release of norepinephrine.
Review paper discussing Pb-calcium interactions in Pb toxicity .
Review paper exploring Pb as a calcium substitute.
Inhibitory effect on [3H]MK-801 binding and loss of binding sites in
neonates.
Triggers acetylcholine release more effectively than calcium.
Reference
Cory-Slechta et al.
(1997a)
Lasley and Gilbert
(1996)
Bielarczyk et al.
(1996)
Kala and Jadhav
(1995)
Tomsig and Suszkiw
(1995)
Long etal. (1994)
Tomsig and Suszkiw
(1993)
Simons (1993b)
Goldstein (1993)
Guilarte and Miceli
(1992)
Shao and Suszkiw
(1991)
-------
>
X
Table AX5-3.1 (cont'd). Summary of Key Studies on Neurochemical Alterations
Subject
Rat
Rat
Exposure Protocol
Hippocampal neurons
Brain protein kinase C
Peak Blood Pb
or [Pb] used
2.5-50|iMPbCl2
l(T10MPb salts
Observed Effects
Pb has a blocking effect on the NMDA subtype of glutamate receptors.
Stimulates brain protein kinase C and diacylglycerol-activated calcium.
Reference
Alkondon et al.
(1990)
Markovac and
Goldstein (1988b)
Abbreviations
GD—gestational day
-------
Table AX5-3.2. Summary of Key Studies on Neurophysiological Assessments
X
to
o
Subject
Rat
PND 22
Rat
PND 42-64
Rat
PND 130-210
Adult rat
Adult rat
Adult rat
Rat
PND 90-1 30
Rat 7-1 8 mo
Rat
PND 13-140
Adult rat
Rat
PND 4-30
Rat
Exposure Protocol
250 ppm Pb(Ac)2
3-6 wks (electro) or 7-13 wks
(immuno)
100, 250, or 500 ppm
Pb(Ac)2 in chow for 3-6 wks
0.2% Pb(Ac)2
in water
Water— 0 .1-1.0% Pb(Ac)2
fromGD 16 to adult
0.2% Pb(Ac)2
in water
0.2% Pb(Ac)2
in water PND 0-21
750 ppm Pb(Ac)2
chow from 50 days pre-mating to
experimental use
Water— 0.2% Pb(Ac)2
from GD 16 to experimental use
750 ppm Pb(Ac)2
chow from 50 days pre-mating to
experimental use
Water— 0.2% Pb(Ac)2
from PND 0-adult
Hippocampal neurons
750 ppm Pb(Ac)2
chow from 50 days pre-mating to
experimental use
Peak Blood Pb
or [Pb] used
30.8 Mg/dL
54.0 Mg/dL
75.4 Mg/dL
11 7.6 Mg/dL
30.1 Mg/dL
30.1 Mg/dL
16.04 Mg/1 00 mL
—
28.5 Mg/dL
—
1-100 MM PbCl2
16.2 Mg/100 mL
Observed Effects
Reduces midbrain dopamine impulse flow and decreases dopamine D]
receptor sensitivity in nucleus accumbens.
Decrease in number of spontaneously active midbrain dopamine neurons.
Review paper examining glutamatergic components contributing to
impairments in synaptic plasticity.
Deficits in synaptic plasticity in the dentate gyrus from early exposure.
Biphasic dose-dependent inhibition of hippocampal LTP.
Chronic Pb exposure significantly decreases range of synaptic plasticity.
Impairments in LTP and paired-pulse facilitation in the hippocampal DG.
NMDA-dependent forms of synaptic plasticity are more vulnerable than
NMDA-independent potentiation or paired pulse-facilitation.
Impairs ability to maintain LTP over time in the dentate gyrus.
Paired-pulse stimulation of CA3 region shows inhibitory mechanisms.
Chronic Pb increases the threshold for LTP in dentate gyrus in vivo.
Identified the nicotinic acetylcholine receptor as a target for Pb.
LTP and learning are impaired if exposed to Pb in the immature brain.
Reference
Tavakoli-Nezhad
and Pitts (2005)
Tavakoli-Nezhad
etal. (2001)
Lasley and Gilbert
(2000)
Gilbert et al.
(1999a)
Gilbert et al.
(1999b)
Zhao etal. (1999)
Ruanetal. (1998)
Gutowski et al.
(1998)
Gilbert and Mack
(1998)
Gutowski et al.
(1997)
Gilbert et al.
(1996)
Ishihara et al.
(1995)
Altmann et al.
(1993)
Abbreviations
GD—gestational day
-------
Table AX5-3.3. Summary of Key Studies on Changes in Sensory Function
Subject
Mice
PND 7-90
Rat
PND 21 or 90
Monkey
13yrs
|x! Monkey
K>
Adult rat
Monkey 6 yr
Rat
PND 90
Exposure Protocol
0.15%Pb(Ac)2
in dams water from PND 0-21
Rat retinas
0.02% and 0.2% Pb(Ac)2
in dams water PND 0-21 and
3 wks as adult
2 mg/kg/d Pb(Ac)2
in capsule for 1 3 y
350 or 600 mg Pb(Ac)2
for 9.75 yrs
Bovine retinas
Rat retinas
0.02% and 0.2% Pb(Ac)2
in dams water PND 0-21
Glycerine capsule with 25 or
2000 ng/kg/d Pb(Ac)2
0.2% Pb(Ac)2
in dams water PND 0-21
Peak Blood Pb
or [Pb] used
26 ng/dL
0.01-10 nM
PbCl2
59.0 ng/dL
168.0 ng/dL
55 |ig/dL
50pM-100nM
Pb(Ac)2
10~9to 10~4M
59.4 ng/dL
220 |ig/dL
0.59 ppm
Observed Effects
Produces a rod photoreceptor- selective apoptosis inhibited by Bcl-xl
overexpression.
Pb and calcium produce rod photoreceptor cell apoptosis via mitochondria.
Functional alterations and apoptotic cell death in the retina.
Mild increase in detection of pure tones outside of threshold.
Consistent prolongations of latencies on the brain stem auditory evoked
potential.
Direct inhibition of purified rod cGMP PDE, magnesium can reverse effect.
Alters several physiological and biochemical properties of rod photoreceptors.
Review paper examining effects upon auditory and visual function.
Inhibits adult rat retinal, but not kidney, Na+, K+-ATPase.
Morphological damage in the visual cortical area VI and V2.
Long-term selective deficits in rod photoreceptor function and biochemistry.
Reference
He et al. (2003)
He et al. (2000)
Fox etal. (1997)
Rice (1997)
Lilienthal and
Winneke(1996)
Srivastava et al.
(1995)
Fox etal. (1994)
Otto and Fox
(1993)
Fox etal. (1991b)
Reuhl et al.
(1989)
Fox and Farber
(1988)
-------
Table AX5-3.4. Summary of Key Studies on Neurobehavioral Toxicity
X
to
to
Subject
Rat, female,
22 wks
Rat
Wistar
Rat, LE,
postweaning
Rat, LE, male
Postweaning
Rat, LE, male
Postweaning
Rat, LE, male
Postweaning
Rat, SD, adult
Rat, SD
Exposure
Protocol
75 or 300 ppm Pb(Ac)2
750 ppm Pb(Ac)2
50 ppm Pb(Ac)2
50 or 1 50 ppm Pb for 3 mo
50 or 1 50 ppm Pb for 3 mo
50 or 1 50 ppm Pb for 3 mo
500 ppm Pb(Ac)2
0.2% Pb(Ac)2 during gestation
and lactation, postweaning
only, or continuously
Peak Blood Pb
or [Pb] Used
39 ng/dL
15 ng/dL
15.1 ng/dL
10.8 and
28.5 ng/dL
9.7 and
26.2 ng/dL after
3 and 7 mo
16.0 and
28.0 ng/dL
20.9 ng/dL
PND56: 3.8,
25.3, and
29.9 ng/dL
Observed Effects
Significantly impaired on the alteration task with variable intertrial delays.
Pb-induced deficits in AAL in rats exposed to Pb either during pre-weaning
or pre- and postweaning: postweaning-only exposure caused reduced deficits
in AAL.
Quinpirole at 0.05 mg/kg reversed the effects of Pb on FI performance;
eticlopride had no effect on response rates in Pb-treated animals.
FR: 1 50-ppm rats — significantly higher response rates and component resets
than the low dose group and controls. Waiting behavior: wait time was lower
in both treated groups. 1 50-ppm rats — increased number of reinforcers and a
higher response to reinforcement ratio than low dose and controls.
D2 agonist quinpirole reversed the Pb-induced effects on FR-response rate,
FR resets, wait reinforcers, and wait time.
No Pb-induced effects on sustained attention.
Chronic Pb exposure attenuated the reinforcing effect of brain stimulation.
No Pb-associated effects in learning performance with just maternal or
postweaning exposure. Continually exposed rats tended to avoid less
frequently and in two-way active avoidance training, did not respond
more frequently.
Reference
Alber and Strupp
(1996)
Altmann et al.
(1993)
Areola and
Jadhav (2001)
Brockel and
Cory-Slechta
(1998)
Brockel and
Cory-Slechta
(1999a)
Brockel and
Cory-Slechta
(1999b)
Burkey and
Nation (1994)
(Chen et al.
(1997a)
-------
Table AX5-3.4 (cont'd). Summary of Key Studies on Neurobehavioral Toxicity
X
to
OJ
Subject
Rat, SD
Rat, LE, male
Rat, LE, male
Rat, LE, male
Rat, LE, male
Rat, LE, male,
PND 21
6-8.5 mo
Rat, LE, male,
PND 21
Rat, F344,
PND 21
8 mo,
16 mo
Exposure
Protocol
0.2% Pb(Ac)2 during gestation
and lactation, postweaning
only, or continuously
50 or 250 ppm Pb(Ac)2
chronically from PND 21
50 or 250 ppm Pb(Ac)2
chronically from PND 21
50 or 250 ppm Pb(Ac)2
in water PND 21 -use
50 or 500 ppm from weaning
50 ppm PbS
8-1 1 mo
50 or 500 ppm
3-5 mo
50 or 250 ppm Pb(Ac)2
2 or 10 mL/kg/d Pb(Ac)2 for
9. 5 mo
Peak Blood Pb
or [Pb] Used
PND 56: 3.8,
25.3, and
29.9 ug/dL
25.1 and
73.5 ug/dL
25.1 and
73.5 ug/dL
73.5 ug/dL
30.3 and 58-
94 ug/dL
-20 ug/dL
73.2 ug/dL
13-18 ug/dL
steady state
Observed Effects
All Pb-treated groups: impaired learning acquisition but unimpaired memory
retention; possible alterations in AMPA receptor binding.
Pb-induced decrements in accuracy on the learning component, but not on the
performance component compared; Pb exposure impaired learning by
increasing preseverative responding on a single lever, even though such
repetitive responding was not directly reinforced.
Pb exposure: attenuated the decline in learning accuracy and the increases in
preseverative responding produced by MK-801; dose-effect curves relating
MK-801 dose to changes in rates of responding were shifted to the right.
Pb-induced potentiation of the accuracy-impairing effects of NMD A by further
increasing the frequencies of errors and likewise potentiated the drug's rate-
suppressing effect; learning impairments are not caused by changes in
dopaminergic function.
50-ppm group: no effects. 500-ppm group: response rates initially decreased,
then reached control levels, primarily due to longer interresponse times.
FI response rates are more sensitive to perturbation by Pb than FR.
Decreased FI response rates (i.e., longer IRTs and lower running rates)
compared to controls.
Demonstrated no consistent changes in FI performance, suggesting that once a
behavior has been acquired, it may be resistant to the adverse effects of
subsequent Pb exposure.
Increased sensitivity to the stimulus properties of dopamine D] and D2 agonists.
Young and old rats: increased VI and FI response rates; adult rats: decreased
response rates on both schedules. Effects on FI seen with 2-mg dose and VI
with only the 10-mg dose.
Reference
Chen etal. (2001)
Cohn etal. (1993)
Cohn and Cory-
Slechta (1993)
Cohn and Cory-
Slechta (1994a,b)
Cory-Slechta
(1986)
Cory-Slechta
(1990a)
Cory-Slechta and
Widowski(1991)
Cory-Slechta
and Pokora
(1991)
-------
Table AX5-3.4 (cont'd). Summary of Key Studies on Neurobehavioral Toxicity
Subject
Rat, F344,
male
Rat, LE, male
Rat, LE, male
Rat, LE, male
^ Rat, LE, male
X
K>
Rat, LE, male
Rat, LE, male
Rat, LE, male
Rat, LE, male
Exposure
Protocol
2orlOmg/kgPb(Ac)2
100or350ppmPb(Ac)2
in dam' s water PND 0-2 1
50orl50ppmPb(Ac)2
from weaning
50 or 150ppmPb(Ac)2
50orl50ppmPb(Ac)2
in water PND 21 -use
50orl50ppmPb(Ac)2
from weaning
100or350ppmPb(Ac)2
from weaning
50 or 500 ppm Pb(Ac)2
from weaning
50 or 500 ppm Pb(Ac)2
from weaning
Peak Blood Pb
or [Pb] Used
2mg: 23; 10 mg:
42 (adult),
-48 (old),
-58 |ig/dL
(young)
34 ng/dL
—
35.7 ng/dL
30.6 ng/dL
15-25
30-50 ng/dL
35.0 |ig/dL
49.1 |ig/dL
49.1 |ig/dL
Observed Effects
Aging caused impaired accuracy: In both young and old rats: Pb-induced
increase in accuracy, at the longest delay periods (12 s) in young rats, and at the
short delay periods in old rats. Adults: not affected by Pb exposure.
Induced functional D2-D3 supersensitivity to the stimulus properties of agonist.
Altered cholinergic sensitivity due to Pb and several agonists.
Postweaning Pb exposure resulted in an MK-801 subsensitivity.
(1) Enhances the stimulus properties of NMD A via a possible
dopaminergic path.
(2) Low level Pb exposure is associated with D] subsensitivity.
Pb exposures attenuated the decrements in rates produced by the two D!
agonists SKF38393 and SKF82958, and at 150 ppm, Pb exposure altered the
rate change associated with the low dose (0.033 mg/kg) of quinpirole.
Post- washout decrease in sensitivity to MK-801 .
Increases FI schedule-controlled behavior in nucleus accumbens.
Both DA and EEDQ, microinjected into the dorsomedial striatum, caused
increases or decreases in FI response rates, which depended on baseline FI
overall rates.
Reference
Cory-Slechta
etal. (1991)
Cory-Slechta
etal. (1992)
Cory-Slechta and
Pokora(1995)
Cory-Slechta
(1995)
Cory-Slechta
etal. (1996a,c)
Cory-Slechta
etal. (1996b)
Cory-Slechta
(1997)
Cory-Slechta
etal. (1998)
Cory-Slechta
et al. (2002)
-------
Table AX5-3.4 (cont'd). Summary of Key Studies on Neurobehavioral Toxicity
X
-------
Table AX5-3.4 (cont'd). Summary of Key Studies on Neurobehavioral Toxicity
Subject
Monkey,
cynomolgus,
9-10 yrs of age
Rat, male,
adult
Rat, LE
Rat, Wistar,
male
Rat, LE,
^_ female
^ Rat, LE, male
^ and female
Exposure
Protocol
50 or 100 ng/kg/d
Pb(Ac)2
500 ppm Pb(Ac)2 in chow for
105 days
1500 ppm Pb(Ac)2 gestation
and lactation
100 mg/kg/body weight by
injection
75 or 300 ppm Pb(Ac)2 in
water GDO experimental use
500 ppm Pb choride during
lactation
Peak Blood Pb
or [Pb] Used
15. 4 and
25.4 |ig/dL; 10.9
and 13.1 |ig/dL,
steady state
28 |ig/dL
3.9 |ig/dL at
PND 50
Not reported
51 ng/dL
42 ng/dL
Observed Effects
Pb-induced impairment in the presence, but not the absence, of irrelevant cues;
in the lower-dose group monkeys, impairment ended when the irrelevant
stimuli became familiar.
Chronic Pb exposure attenuates cocaine-induced behavioral activation.
Pb + enriched environment: enhanced performance in water maze; increased
gene expression in the hipppocampus of NMDAR subunit 1 and BDNF.
Pb-induced deficits in memory component of the radial arm maze test and in
retention of passive avoidance learning.
Impairment of reversal learning as an associative deficit.
PND 11: no Pb-induced sex differences, effects on pup activity, and
differences in pup retrieval by dams.
Reference
Gilbert and Rice
(1987)
Grover et al.
(1993)
Guilarte et al.
(2003)
Haider et al.
(2005)
Hilson and Strupp
(1997)
Holloway and
Thor(1987)
Rat, LE 250 ppm Pb(Ac)2 chronically
from gestation
Hippocampal
Pb levels
PND 21: 1.73;
PND 56: 1.02;
PND 91:
0.91 ng/g
PND 26: Pb treatment influenced all social behavior tested (i.e., investigation
duration and frequency, crossover frequency, pinning) but did not change
activity levels.
PND 36: Pb-treated pups demonstrated increased crossover frequencies but no
change in activity levels compared to controls.
Pb-exposure had no effect on working memory at any age tested, but did affect
reference memory (significant in females and nearly significant in males) in the
PND 21 rats.
Jettetal. (1997)
-------
Table AX5-3.4 (cont'd). Summary of Key Studies on Neurobehavioral Toxicity
Subject
Rat, LE, male
Monkey,
rhesus
Monkey,
rhesus
Monkey,
rhesus
\S Monkey,
YI rhesus,
K> 5-6 yrs
Monkey,
rhesus,
7-9 yrs
Monkey,
rhesus
Monkey,
rhesus
Exposure
Protocol
750 ppm Pb(Ac)2
maternally, permanently,
or postweaning only
Pb(Ac)2 testing first 4 wks of
life
1 mg/kg/d Pb(Ac)2
PND 5-PND 365
Pb(Ac)2 testing first 4 wks of
life
10 mg/kg/d pulses (2) and
chronic 0.7 for first yr of life
10 mg/kg/d pulses (2) and
chronic 0.7 for first yr of life
10 mg/kg/d pulses (2) and
chronic 0.7 for first yr of life
350 or 600 ppm
in utero
Peak Blood Pb
or [Pb] Used
At PND 100
1.8,21.3,22.8,
and 26. 3 ug/dL
35 ug/dL
First yr
-70 ug/dL
16-moPE:
-35 ug/dL
35 ug/dL
250-300 ug/dL
peak
80 for rest of yr
1^ wk:
63 ug/dL
5-6 wk: 174
4 yrs: 4
7 yrs: 2
wk5: 56 during;
remainder of first
6 mo: 33-
43 ug/dL
50 and 110 ug/dL
Observed Effects
Maternal and permanent exposure: impaired water maze performance, with
maternal exposure producing both the greatest escape latency and longest
escape path length. No effects on performance in the postweaning exposure
groups.
Pb-induced greater agitation, climbing, fear, and exploration of the periphery.
First yr: Pb-induced disruption of social play, and increases in both self-
stimulation and fearful behavior were observed. 16 mo: continued
disruption.
Few differences between control and Pb-exposed monkeys were seen; less
stability in SNAP performance.
Pb-induced deficits occurred most commonly with short intertrial delays;
lose-shift errors, possibly due to perseveration.
Chronic L-dopa ameliorated the Pb-induced DSA deficits, which returned
following cessation of L-dopa administration: implicates DA mechanisms in
these impairments.
First 6 wks: Pb-induced lowered muscle tonus and greater agitation, no
effects on sensorimotor measures. PND 14: no Pb-related effects on object
permanence task.
2 mo: Pb-induced decreased visual attentiveness in visual exploration task.
At age 12 to 15 mo, the high-dose group exhibited deficits in simple
discrimination learning: both groups showed impairments in the more
complex learning set formation trials; activity at 12-15 mo showed no
Pb-related effects.
Reference
Kuhlmann et al.
(1997)
Lasky and Laughlin
(2001)
Laughlin et al.
(1991)
Laughlin et al.
(1999)
Levin and Bowman
(1986)
Levin etal. (1987)
Levin etal. (1988)
Lilienthal et al.
(1986)
-------
Table AX5-3.4 (cont'd). Summary of Key Studies on Neurobehavioral Toxicity
X
to
oo
Subject
Rat, SD, male,
PND 60
Rat, Wistar
Rat, LE
RatLE,
PND 53
Rat, Wistar
tested at
PND 100 and
PND 142
Rat, Wistar,
female
Rat, Wistar,
female
Rat, Wistar,
PND 80
Exposure
Protocol
8orl6mgPb(Ac)2
500 ppm Pb(Ac)2 through
pregnancy and lactation
75 or 300 ppm Pb(Ac)2
continuously
300 or 600 ppm during
gestation or gestation and
lactation
750 ppm though PND 16
maternal exposure or
chronically
750 ppm Pb(Ac)2
750 ppm Pb(Ac)2
400 mg/L Pb C12 in dam's
water PND 1-30
Peak Blood Pb
or [Pb] Used
6.8 ng/dL
41.24 ng/dL
(dams),
21.24 ng/dL
(PND 23),
(PND 70)
36 ng/dL
PND 8: 36^3;
PND 24: 27-34;
PND 53: 131-
158
PND 110:
maternally
exposed: <3;
chronic:
34 ng/dL
17.3 ng/dL at
PND 16
32-39 ng/dL
continuous
exposure
17.3 ng/dL at
PND 16
32-39 |ig/dL
continuous
exposure
PND 8:
10-15 ng/dL;
PND 21: -45;
PND 80: 1-4
Observed Effects
Long-lasting changes in drug responsiveness to cocaine and related drugs.
PND 23: Pb-induced increased ambulation in the open-field tests, decreased
exploratory behavior in the holeboard tests, and no differences from control in
the elevated maze tests.
PND 70: Pb-induced increase in head dipping in the holeboard test, decrease
in social interaction time. No differences in the rotarod tests.
Impaired learning of a visual discrimination task.
No Pb-induced differences in learning rate, motivation, or response latency
for correct or incorrect responses. Pb-induced: increases in errors of
omission when a delay was imposed prior to cue presentation, trials that
followed an incorrect response, and response initiation.
Both Pb-treated groups learned the original discrimination comparably to
controls, but showed a deficit in retention; Pb-treated female rats took longer
to reach criterion in the acquisition learning and longer to eat the pellets in the
retention phase.
Pb-induced deficits in acquisition of learning, but not with concurrent
hippocampal lesions. Four wks later, both lesioned and Pb-treated animals
showed impaired retention.
Pb and lesions of amygdala showed impairments in the acquisition phase of
the maze and impaired passive avoidance; neither treatment affected
locomotor activity. Continuously exposed rats showed greater deficits.
48 h PE: no Pb-induced changes in recall; 5 days PE: decline in recall
latency.
Reference
Miller etal. (2001)
Moreira et al.
(2001)
Morgan et al.
(2000)
Morgan et al.
(2001)
Munozetal. (1986)
Munozetal. (1988)
Munozetal. (1989)
Murphy and Regan
(1999)
-------
Table AX5-3.4 (cont'd). Summary of Key Studies on Neurobehavioral Toxicity
X
to
VO
Subject
Rat, SD, male,
adult
Rat, SD,
PND 120
Rat, SD,
PND 70
Rabbit, Dutch
Belted, male
Monkey,
squirrel
Monkey,
squirrel
Monkey,
cynomolgus
Monkey,
cynomolgus
Monkey,
cynomolgus,
7-8 yr
Monkey,
cynomolgus,
7-8 yr
Exposure
Protocol
500 ppm Pb(Ac)2
16 mg Pb(Ac)2 via gavage
30 days pre-pregnancy to
PND 21
16 mg Pb(Ac)2 via gavage
30 days pre-pregnancy to
PND 21
Pb(Ac)2
Mother's blood Pb from
gestation week 5-birth
In utero exposure
2 mg/kg/d of Pb(Ac)2
continuously
50orlOO|ig/kg/dPb(Ac)2
chronically beginning
at PND 1
1500|ig/kg/dPb(Ac)2
1500|ig/kg/dPb(Ac)2
continuously from birth,
during infancy only, or
beginning after infancy
Peak Blood Pb
or [Pb] Used
28.91 ng/dL
38.0 ng/dL
53.24 ng/dL
20, 40, and
80 ng/dL
21-79 ng/dL
21-70 ng/dL
maternal
HSng/dLat
PND 100
33 |ig/dL by
PND 270
PND 100: 15.4
and 25.4
PND 300: 10.9
and 13.1 ng/dL
36 ng/dL
36 |ig/dL
Observed Effects
Decreases sensitization to the locomotor-stimulating effects of cocaine.
Self-administering rats prenatally exposed to Pb demonstrate and increased
sensitivity to the relapse phase of cocaine abuse.
Increased sensitivity to cocaine in rats perinatally exposed to Pb.
Exposed males mated with nonexposed females. Offspring at PND 25
showed Pb-induced effects on exploratory behavior.
Reduced sensitivity to changes in reinforcement contingencies during
behavioral transitions and in steady state.
Pb-induced increase in the number of responses that failed to adequately
displace the bar in the FR schedule and possible subtle motor impairments.
At PND 60: Pb-induced increased mean FR pause times, and, decreased FI
pause times. At 3 yrs of age: Pb-induced increased FI run rate, pause time,
and index of curvature. At both ages, Pb-induced increased variability of
performance.
Delayed alternation at 7-8 yrs of age: Pb-induced impairment of initial
acquisition of tasks; longer delays between alternations resulted in poorer
performance and perseverative behavior, sometimes lasting for hours.
Pb exposure in infancy only impaired spatial discrimination reversal tasks.
All Pb-treated groups: same impairments of initial acquisition, indiscriminate
responding, greater impairment with longer delays, and preseverative
responses.
Reference
Nation etal. (1996)
Nation et al. (2003)
Nation et al. (2004)
Nelson etal. (1997)
Newland et al.
(1994)
Newland et al.
(1996)
Rice(1988a)
Rice and Karpinski
(1988)
Rice (1990)
Rice and Gilbert
(1990b)
-------
Table AX5-3.4 (cont'd). Summary of Key Studies on Neurobehavioral Toxicity
X
1
o
Subject
Monkey,
cynomolgus,
5-6 yr
Monkey,
cynomolgus,
3 or 7 yr
Monkey,
cynomolgus,
8-9 yr
Monkey,
cynomolgus,
0.5 or 3 yr
Rat, adult
Exposure
Protocol
1500|ig/kg/dPb(Ac)2
continuously from birth, during
infancy only, or beginning after
infancy
1500|ig/kg/dPb(Ac)2
1500|ig/kg/dPb(Ac)2
continuously from birth, during
infancy only, or beginning after
infancy
2000 ng/kg/d Pb(Ac)2
16mgPb(Ac)2
Peak Blood Pb
or [Pb] Used
36 ng/dL
36 ng/dL
36 ng/dL
HS^g/dL
83.2 |ig/dL
Observed Effects
Post-infancy exposure impairs nonspatial discrimination reversal while
exposure during infancy exacerbates the effect.
Pb exposure during different developmental periods produce different effects
on Fl performance in juveniles versus adults.
Pb-treated monkeys in all three exposure groups learned more slowly, with
less impairment in infancy-only exposures, and showed perseverative
behavior.
Decreased interresponse times and a greater ratio of responses per
reinforcement on the differential reinforcement of low rate schedule.
Developmental Pb exposure results in enhanced acquisition of cocaine self-
Reference
Rice and Gilbert
(1990a)
Rice(1992a)
Rice(1992c)
Rice(1992b)
Rocha et al. (2005)
pregnancy to PND 21
Rat
Rat, F344
Rat, LE, male
Rat, Wistar
Rat, Wistar
0.5, 2.0, or 4.0 mM Pb(Ac)2 in
drinking water
0.2% Pb(Ac)2 from
PND 25 until testing at
PND 100
750 ppm Pb(Ac)2
gestation and lactation
0.03%, 0.09%,
or 0.27%
Pb(Ac)2
gestationally
ll-50ng/dL
-42 ng/dL
-30 in Pb
PND 30:
25 ng/dL
PND 90:
0.113ng/dL
-30, -33, and
-42 ng/dL at
PND 0, tested at
PND 49
Pb-induced decreased retention in shuttle avoidance task. Pb-associated
increase in locomotor activity.
Pb-induced better performance using extra-maze spatial cues; Pb-treated rats
spent less time on the periphery of the maze.
Pb-exposure + isolation: spatial learning deficits. Pb-exposure + enrichment:
performed better than the isolated Pb group. Pb-induced decreases in
hippocampal levels of BDNF, NGF-p1, NT-3, and basic FGF.
At PND 30 and 90: no Pb-associated changes in elevated maze behavior.
PND 30: decreased freezing, increased ambulation, and increased grooming.
PND 90: Pb-induced decreased freezing and increased ambulation.
Offspring of Pb-treated females mated with nonexposed males.
F2 generation at PND 30 and 90: increased ambulation and decreased
grooming.
Male offspring: all three doses impaired memory retrieval. Female offspring:
only the low dose affected memory retrieval. Motor performance and vision
were not affected by Pb.
Rodrigues et al.
(1996a)
Salinas and Huff
(2002)
Schneider et al.
(2001)
Trombini et al.
(2001)
Yang et al. (2003)
-------
Table AX5-3.5. Summary of Key Studies on Cell Morphology and Metal Disposition
Subject
Exposure Protocol
Peak Blood Pb
or [Pb] Used
Observed Effects
Reference
X
Rat, PND 110 Water—0.2% Pb(Ac)2 from
GD16-PND21oruse
Rat C6 glioma cells and human
astrocytoma cells
Rat pup astroglial cell culture
Rat, PND 60 1500 ppm Pb(Ac)2 for 30-35 days
Cultured neurospheres
Rat,
embryos
Young rat
Rat
Human,
PND 0-20 = 600 ug/dL
PND 20^0 = 20-60 ug/dL
Cultured oligodendrite progenitor
cells—PND 2
Cultured oligodendrite progenitor
cells—PND 2
Cultured cerebellar granule neurons
Cultured C6 glioma cells
Rat and human Cultured rat astroglial,
human neuroblastoma
Rat
Cultured GH3, C6, and HEK293
cells
2 g/1 Pb(Ac)2 in weanlings for 3 mo
5-10 uMPb(Ac)2
10uMPb(Ac)2
20.0 ug/dL
0.1-100 uM
Pb(Ac)2
131.3 ug/dL
1 uMPb(Ac)2
0.1-100 uM
Pb(Ac)2
5-50 uM Pb(NO3)2
or Pb(ClO4)2
1 uMPb(Ac)2
1 uMPb(Ac)2
l-10uMPb(NO3)2
39 ug/dL
Reduction in hippocampal neurogenesis with no spatial learning
impairments.
Directly targets GRP78 and induces its compartmentalized
redistribution. GRP78 plays a protective role in Pb neurotoxicity.
Oxidative stress in astroglia results from Pb impairment of the Cu
transporter Atpase (AtpVa).
Significant deleterious effects on progenitor cell proliferation.
Differentially affects proliferation and differentiation of embryonic
neural stem cells originating from different brain regions.
Blood Pb during succimer chelation are not an immediate indicator
of brain. Brain Pb values are slower to respond even though blood
Pb is normal.
Pb inhibition of proliferation and differentiation of oligodendrocyte
cells requires PKC.
Interferes with maturation of oligodendrocyte progenitor cells.
Specific transport systems carry Pb into neurons.
Induces GRP78 protein expression and GRP78 is a strong Pb
chelator.
Half-life of blood Pb was dependent upon exposure duration,
ranging 10-38 mo.
Immature astroglia vs. neuronal cells are most likely to bind Pb in
the brain.
Review paper addressing Pb-binding proteins in the brain and
kidney.
Cellular uptake of Pb is activated by depletion of intracellular
calcium.
Chronic low Pb levels induces blood brain barrier dysfunction.
Gilbert et al. (2005)
Qian et al. (2005a)
Qian et al. (2005b)
Schneider et al.
(2005)
Huang and Schneider
(2004)
Stangle et al. (2004)
Deng and Poretz
(2002)
Dengetal. (2001)
Mazzolini et al.
(2001)
Qian et al. (2000)
Manton et al. (2000)
Lindahletal. (1999)
Fowler (1998)
Kerper and Hinkle
(1997)
Struzynska et al.
(1997)
-------
Table AX5-3.5 (cont'd). Summary of Key Studies on Cell Morphology and Metal Disposition
Subject
Exposure Protocol
Peak Blood Pb
or [Pb] Used
Observed Effects
Reference
X
60 ug/dL
Discovered that albumin rarely enters brain from blood.
Results indicate a positive correlation between p32/6.3 levels and
neuronal maturation.
Examined the relationship between Pb and nuclear protein p32/6.3
and its abundance in intranuclear inclusion bodies.
Attenuation of Pb inhibition of ALAD involves sequestration of Pb
and a donation of zinc to the enzyme.
Injections of Pb-203 showed a linear uptake into three regions of
the brain, suggesting that the blood-brain barrier is rate-limiting.
Blood Pb half-life is affected by duration of exposure, age, and
length of follow-up.
Blood Pb half-life is dependent upon the length of exposure.
Bradbury et al.
(1991)
Klann and Shelton
(1990)
Klann and Shelton
(1989)
Goeringetal. (1986)
Bradbury and Deane
(1986)
Hryhorczuk et al.
(1985)
O'Flaherty et al.
(1982)
-------
Table AX5-3.6. Key Studies Evaluating Chelation of Pb in Brain
Subject
Exposure Protocol
Chelator
Observed Effects
Reference
X
Rat, male, LE, Group 1: 50 ppm Pb acetate in CaEDTA
PND 21 drinking water from PND 21
for 3^ mo, after which they
were given i.p. injections of
75 or 150 mg/kg CaEDTA for
either 1, 2, 3, 4, or 5 days.
Group 2: 25 or 500 ppm Pb
acetate followed by a single
injection of either 75 or
150 mg/kg CaEDTA. Twenty-
four hour urine samples were
collected following CaEDTA
injections.
Rat, male, LE, 50 ppm Pb acetate from DMSA
PND 21 weaning until testing 3^1 mo
later. The rats received either
25 or 50 mg/kg DMSA for 1, 2,
3,4, or 5 days and tissues were
evaluated 24 h following the
last injection.
Group 1: Blood Pb declined after the first CaEDTA injection, but did not drop Cory-Slechta et al.
further with subsequent CaEDTA and never dropped below control levels (1987)
(5 ug/dL). Pb levels in urine increased similarly with both doses of CaEDTA.
Pb was found to be mobilized from both bone and kidney and initially
redistributed to brain and liver. Subsequent CaEDTA injections caused
declines in brain and liver Pb levels, but no net loss of Pb.
Group 2: a single injection of 150 mg/kg CaEDTA caused marked elevation
of brain Pb, which called into question use of injections of CaEDTA in
clinical diagnostic procedures.
Blood Pb was decreased by DMSA dose-dependently, with levels dropping to
<5 ug/dL after 3 injection of the higher dose and 4 injections of the lower
dose. Pb levels dropped in brain and kidney immediately, and in liver
following a delay. Bone Pb did not decline, which contrasts with earlier
studies showing mobilization from bone following DMSA chelation. Another
group in this study received the same 5 days of DMSA injections, but was
evaluated 4 mo later. Pb concentrations in all tissues were comparable to
those seen in the first group, indicating that chelation therapy must be
continued to lower tissue Pb levels.
Cory-Slechta (1988)
Rat, female, Given 206Pb-enriched drinking
Wistar water at 210 ng Pb/mL for
36 h. Following an overnight
fast, the rats were injected with
one 0.25 mL i.p. injection of
0.11 mmol/kg DMSA. Pb
levels in blood, kidney, brain,
and tibia assessed 24 h later.
DMSA Blood Pb declined 40%, Pb in urine increased 1500%, and changes in kidney Smith and Flegal
and brain tissue Pb levels varied inconsistently. Chelation did not result in (1992)
increased excretion of skeletal Pb compared to controls, nor did it show a
redistribution of Pb to brain.
-------
Table AX5-3.6 (cont'd). Key Studies Evaluating Chelation of Pb in Brain
Subject
Exposure Protocol
Chelator
Observed Effects
Reference
Rat, female, 100 ppm Pb acetate in drinking CaEDTA
Albino water for 4 wks. During the last 2
days of that exposure, the rats were
administered two i.p. injections of 1
jig stable 204Pb tracer. Animals then
received 1 to 5 consecutive days of
150 mg/kg CaEDTA ; assayed 24 h
following the last injection.
Rat, male, SD Chelation with ongoing Pb DMSA
rats at 6-7 wks exposure; blood Pb were -45 ng/dL;
550 ppm Pb acetate in drinking
water for 35 days.
Group 1: continued on Pb only for
21 days.
X Group 2: received continued Pb
Y1 plus oral DMSA at 16, 32, 120, or
£ 240 mg/kg/d for 21 days.
Group 3: discontinued on Pb after
the first 35 days and received oral
DMSA (16, 32, or 240 mg/kg/d).
Rat, male, Dosed with 1000 ppm Pb in CaEDTA and
Wistar drinking water for 4 mo, then treated DMSA
for 5 days with: saline; 25 mg/kg
DMSA orally, twice daily; 75 mg/kg
CaEDTA i.p. once daily; or
25 mg/kg DMSA twice daily plus
75 mg/kg CaEDTA i.p. once daily.
Blood Pb resulting from these
treatments were 46, 22, 28, and 13
Hg/dL, respectively and brain Pb
levels were 49, 38, 26, and 22 ng/g,
respectively.
No redistribution of endogenous Pb into the brain following one
CaEDTA dose, no measurable reduction in brain or bone Pb levels, and
reductions in both kidney and blood Pb levels. Additionally, over the
first day of treatment, CaEDTA reduced the 204Pb tracer more
effectively than the Pb from chronic exposure, indicating greater
biologically availability of Pb from recent exposures.
DMSA treatment increased urinary Pb and decreased levels of Pb in
blood, brain, bone, kidney, and liver, even with continued Pb exposure.
Seatonetal. (1999)
Pappasetal. (1995)
The combined treatments produced an additive response in urinary Pb
elimination and elimination from blood, liver, kidney, brain, and femur.
Flora etal. (1995)
-------
Table AX5-3.6 (cont'd). Key Studies Evaluating Chelation of Pb in Brain
Subject
Exposure Protocol
Chelator
Observed Effects
Reference
X
Rat, female, Group 1: 325 |ig/mL Pb
LE acetate maternally through
weaning, and then to 30 |ig/mL
until PND 30. Chelation
treatment consisted of 7 days of
30 or 60 mg/kg/d DMSA.
Group 2: 325 ng/dL
maternally and through
PND 40 and then treated to
DMSA for 7 or 21 days.
Rat, LE Exposed gestationally to
600 ng/mL Pb acetate, then
split into high and low dose
groups.
Low dose group: 20 ng/mL
from PND 21-28, followed by
30 ng/mL from PND 29^0.
High dose group: 40 ng/mL
from PND 21-28, followed by
60 ng/mL from PND 29^0.
DMSA treatment consisted of
50 mg/kg/d for 1 wk, then
25 mg/kg/d for 2 wks. Rats
received either 1 or
2 treatments at PND 40 or
40 and 70.
DMSA
DMSA
Seven days of DMSA effectively removed Pb from both blood and brain.
Treatment beyond 7 days further reduced brain Pb, but not blood Pb.
Reductions in Pb were greater in the second group, which the authors attribute
to the higher exposures used. The authors also hypothesize that DMSA-
mediated reduction in blood Pb are a poor indicator of reductions in brain Pb.
Smith etal. (1998)
One treatment lowered both blood Pb and brain Pb, but the brain reductions
lagged the blood reductions both temporally and in magnitude. Following the
second DMSA treatment, they observed a rebound in blood, but not brain Pb
levels.
Stangle et al. (2004)
-------
Table AX5-3.6 (cont'd). Key Studies Evaluating Chelation of Pb in Brain
X
Subject
Monkey,
Rhesus,
11-yr-old with
history of
testing for
CllCCLo (Jl
housing and
rearing and
which were
used in drug
challenge
studies, were
used after at
least 1.5 yrs
had elapsed
since the last
testing
Rat, male, LE,
PND55
Exposure Protocol
—50 mg/kg/d Pb acetate, and
then doses were adjusted to
produce a target blood Pb of
35^0 ng/dL. Following 5 wks
of Pb exposure, the monkeys
were administered 204Pb tracer
starting 4 days before chelation.
DMSA was administered for
5 days at 30 mg/kg/d, followed
by 14 days at 20 mg/kg/d.
At PND 55, rats were started on
an FI schedule, where a Pb-
Chelator Observed Effects
DMSA Brain levels of Pb and tracer, measured in prefrontal cortex, hippocampus, and
striatum, were not different from controls, indicating that DMSA was not
effective in reducing brain Pb levels. They also found a poor correlation
between brain and blood Pb levels.
CaEDTA Chelation treatment failed to reverse the learning deficits in Pb-exposed
animals and further increased the proportion of short interresponse times. The
Reference
Creminetal. (1999)
Cory-Slechta and
Weiss (1989)
induced increase in
interresponse time was
observed. Pb exposure was
then terminated and daily
injections of 75 or 150 mg/kg
CaEDTA were given for
5 consecutive days.
Rat, male, 150 or 2000 ppm Pb for
F344, 7-wk- 21 days, then distilled water for
old male the next 21 days. Blood Pb
peaked at 37 and 82 ng/dL,
respectively. Chelation:
50 mg/kg by oral gavage,
3 times a week for up to
21 days; reduced blood Pb to
22 and 56 ng/dL, respectively.
authors suggest that this effect may be due to the CaEDTA-mediated
redistribution of Pb from bone to brain.
DMSA
Pb-induced increase in rearing behavior was observed. DMSA reduced the
Pb-induced effects on activity. Levels of brain glial fibrillary acidic protein
(GFAP) were also assessed in these animals. A Pb-induced dose-dependent
increase in GFAP was observed in hippocampus, cortex, and cerebellum,
which was reversed by DMSA treatment.
Gong and Evans
(1997)
-------
ANNEX TABLES AX5-4
AX5-37
-------
Table AX5-4.1. Effect of Lead on Reproduction and Development in Mammals Effects on Offspring
X
OJ
oo
Citation
Al-Hakkak
et al. (1988)
Appleton
(1991)
Bataineh
et al. (1998)
Berry et al.
(2002)
Bogden et al.
(1995)
Camoratto
et al. (1993)
Corpas
(2002a)
Corpas
(2002b)
Species/
Strain/ Age
Mouse/BALB/c,
weaning
Rat/Long-Evans
hooded, adult
Rat/Sprague-
Dawley, adult
Rat/Sprague-
Dawley, 21 days
old
Rat/Sprague-
Dawley, 12 wks
old
Rat/Sprague-
Dawley, adult
Rat/Wistar, adult
Rat/ Albino
(NOS), adult
Dose/Route/
Form/Duration
0, 25, 50 mg Pb monoxide
alloy/kg in chow for 35-
70 days
Pb acetate single dose by i.v. at
30 mg/kg
1000 ppm Pb acetate in
drinking water for 12 wks
Pb nitrate (1000 ppm Pb)
in drinking water for 6 wks
250 mg/L of Pb acetate in
drinking water from GD 1 until
after 1 wk after weaning
0.02% Pb nitrate in drinking
water from gestation day 5 of
dams until PND 4 of offspring
Pb acetate 0 or 300 mg/L in
drinking water during gestation
and lactation
Pb acetate 0 or 300 mg/L in
drinking water during gestation
Endpoint
Reduced number of spermatogenia and spermatocytes in the 50 mg group after 70 days;
reduced number of implantations after mating (after 35 days exposure).
Increase in serum calcium and phosphorous; SEM analysis revealed 'Pb line' in tooth
that was composed of hypomineralized interglobular dentine.
Fertility was reduced; total number of resorptions was increased in female rats
impregnated by males.
Mean plasma growth hormone levels decreased by 44.6%; reduced mean growth
hormone amplitude by 37.5%, mean nadir concentration by 60%, and growth hormone
peak area by 35%; findings are consistent with decreased hypothalamic growth
hormone-releasing factor secretion or reduced somatotrope responsiveness; exogenous
growth hormone in Pb-treated and control rats, this response was blunted by the Pb
treatment; plasma IGF1 concentration was not significantly affected by Pb treatment.
Dam and pup hemoglobin concentrations, hematocrit, and body weights and lengths
were reduced.
Female pups exposed to Pb beginning in utero were smaller, no corresponding effect in
males; pituitary responsiveness to a hypothalamic stimulus.
Alterations in hepatic system of neonates (PND 12) and pups (PND 21); reductions in
hemoglobin, iron, alkaline and acid phosphatase levels, and hepatic glycogen, and
elevated blood glucose.
Effects energy metabolism; decrease in testis and seminal vesicle weights, and an
increase in DNA and RNA levels on PN day 2 1 ; protein was significantly decreased,
Blood Lead Concentration
(PbB)
PbB not reported
PbB not reported
PbB not reported
PbB 37.40 ± 3.60 ug/dL
PbB <15 ug/dL
PbB 17-43 ug/dL
PbB -22 ug/dL
PbB 54-143 ug/dL
and lactation
alkaline and acid phosphatase levels of the gonads were reduced; reduction of the
thickness of the epithelium and seminiferous tubule diameter.
-------
Table AX5-4.1 (cont'd). Effect of Lead on Reproduction and Development in Mammals Effects on Offspring
Citation
Species/
Strain/Age
Dose/Route/
Form/Duration
Endpoint
Blood Lead Concentration
(PbB)
Cory-Slechta
et al. (2004)T
Rat/Long-Evans,
adult
Dey et al.
(2001)
Mouse/Albino
(NOS), -100 g
X
-------
Table AX5-4.1 (cont'd). Effect of Lead on Reproduction and Development in Mammals Effects on Offspring
Citation
Species/
Strain/Age
Dose/Route/
Form/Duration
Endpoint
Blood Lead Concentration
(PbB)
Fox et al.
(1997)T
X
Gandley et al.
(1999)
Govoni et al.
(1984)
Rat/Long-Evans
hooded, adult
Rat/Sprague-
Dawley, adult
Rat/Sprague-
Dawley, adult
Hamilton et al.
(1994)
Han et al.
(2000)
Rat/Sprague-
Dawley,
25 days old
Rat/Sprague-
Dawley, 5 wks
old
Hanna et al.
(1997)
Mouse/Swiss
ICR
preimplantation
embryos
0.02 or 0.2% Pb acetate in
drinking water from PND 0—
PND 21; 8 female pups per
litter control pups; 8 pups per
litter low level exposure;
8 pups per litter moderate level
exposure (number of litters per
dose unspecified)
Male rats exposed to 25 or
250 ppm acetate Pb in drinking
water for at least 35 days prior
to breeding
2.5 mg/mL Pb acetate in
drinking water from GD 16 to
postnatal week 8
Pb acetate in drinking water at
250, 500 or 1000 ppm; 8 wks
prior to mating through GD 21
250 mg/mL Pb acetate in
drinking water for 5 wks
followed by 4 wks no exposure
(mated at end of 4-wk no
exposure period)
In vitro incubation of two- and
four-cell embryos with 0.05—
200 uM Pb acetate for 72 hr
(time required for blastocyst
formation)
Developmental and adult Pb exposure for 6 wks produced age and dose-dependent
retinal degeneration such that rods and bipolar cells were selectively lost; at the
ultrastructural level, all dying cells exhibit the classical morphological features of
apoptotic cell death; decrease in the number of rods was correlated with the loss of
rhodopsin content per eye confirming that rods were directly affected by Pb (p < 0.05);
single-flash rod ERGs and cone ERGs obtained from Pb-exposed rats demonstrated that
there were age- and dose-dependent decreases in the rod a-wave and b-wave sensitivity
and maximum amplitudes without any effect on cones; in adult rats exposed to Pb for
3 wks, qualitatively similar ERG changes occurred in the absence of cell loss or
decrease in rhodopsin content (p < 0.05); developmental and adult Pb exposure for
three and 6 wks produced age- and dose-dependent decreases in retinal cGMP
phosphodiesterase (PDE) activity resulting in increased CGMP levels (p < 0.05); retinas
of developing and adult rats exposed to Pb exhibit qualitatively similar rod mediated
ERG alterations as well as rod and bipolar apoptotic cell death (p < 0.05); similar
biochemical mechanism such as the inhibition of rod and bipolar cell cGMP PDE,
varying only in degree and duration, underlies both the Pb-induced ERG rod-mediated
deficits and the rod and bipolar apoptotic cell death (p < 0.05).
Fertility was reduced in males with PbB in range 27-60 ug/dL, Pb was found to affect
initial genomic expression in embryos fathered by male rats with blood Pb levels as low
as 15-23 ug/dL; dose-dependant increases were seen in an unidentified set of proteins
with a relative molecular weight of —70 kDa.
Decreased sulpiride binding in the pituitary is consistent with the elevated serum PRL
concentrations previously described in Pb-exposed rats; DOPAc concentrations were
reduced by 21% in Pb-treated rats.
Altered growth rates; reduced early postnatal growth; decreased fetal body weight.
Pups born to Pb-exposed dams had significantly (p <
and birth lengths.
0.0001) lower mean birth weights
Exposure of embryos to Pb was only toxic at 200 uM, which reduced cell proliferation
and blastocyst formation.
PbB weanlings 19 ± 3 (low
exposure) or 59 ± 8 ug/dL
(moderate exposure), adult
7±2ng/dL(atPND90)
PbB 27-60 ug/dL (fathers)
15-23 ug/dL (offspring)
PbB 71 ± 8 ug/dL
PbB 40-100 ug/dL
PbB 10-70 ug/dL
PbB not reported
-------
Table AX5-4.1 (cont'd). Effect of Lead on Reproduction and Development in Mammals Effects on Offspring
Citation
Species/
Strain/Age
Dose/Route/
Form/Duration
Endpoint
Blood Lead Concentration
(PbB)
Low-level exposure (PbB 2-13 ug/dL) reduced red cell synthesis (p < 0.05); high-level
exposure (PbB 0.6-2 ug/dL) enhanced red cell synthesis (p < 0.05).
In females: accelerated time to puberty at PbB <3 ug/dL; delayed time to puberty at
3-13 ug/dL.
Increase in pre- and perinatal mortality among squirrel monkeys receiving Pb acetate
p.o. during the last two-thirds of pregnancy (45% vs. 7-8% among controls); mean
maternal PbB was 54 ug/dL (39-82 ug/dL); statistically significant reductions in mean
birth weight were observed in Pb-exposed monkeys as compared to controls; effects
occurred without clinical manifestation of toxic effects in the mothers.
Dose-dependent reduction in placental weight (p < 0.0007); various pathological lesions
were seen in the placentas (n = 4), including hemorrhages, hyalinization of the
parenchyma with destruction of the villi and massive vacuolization of chorion
epithelium; effects occurred without clinical manifestation of toxic effects in the
mothers.
Male offspring of dams exhibited reduced sperm counts, altered male reproductive
behavior, and enlarged prostates later in life; females exhibited delayed puberty,
menstrual irregularities, and an absence of observable corpora lutea; males and females
exhibited irregular release patterns of both FSH and LH later in life.
Chemical analysis showed Pb was readily transferred across placenta; Pb caused
moderate, statistically significant, increase in frequency of SCEs in maternal bone
marrow cells and significant reduction in NORs at the 2 highest dose levels (150 and
200 mg/kg); animals showed several specific chromosomal aberrations, mostly
deletions, in maternal bone, marrow, and fetal cells; aneupoidy was found to be
frequently associated with the lowest dose levels of Pb nitrate (100 mg/kg); increased
embryonic resorption and reduced placental weights.
Decrease in litter size, pup survival, and birth weight; food consumption, body weight,
and fertility were not altered in 20 wk exposure period.
X
-k
lavicoli et al.
(2003)
lavicoli et al.
(2004)
Logdberg
et al. (1987)
McGivern
etal. (1991)T
Nayak et al.
(1989a)
Mouse/Swiss,
adult
Mouse/Swiss,
adult
Monkey/
Squirrel, adult
Logdberg Monkey/
et al. (1998) Squirrel, adult
Rat/Sprague-
Dawley, adult
Mouse/Swiss
Webster, adult
Piasek and Rat/Wistar,
Kostial (1991) 10 wks old
Pb acetate in food (0.02, 0.06,
0.11, 0.2, 2, 4, 20, 40 ppm)
exposure began 1 day after
mating until litter was 90 days
old one litter of mice exposed
to each dietary concentration
Pb acetate in feed; exposure
began 1 day after mating until
litter was 90 days old
Pb acetate p.o. exposure of
gravid squirrel monkeys from
week 9 of gestation through
PNDO
Pb acetate (varying
concentrations <0.1% in diet);
maternal dosing from 5-
8.5 wks pregnant to PND 1;
11 control monkeys, 3 low-Pb
exposure group (PbB
24 ug/dL), 7 medium Pb group
(PbB 40 ug/dL, 5 high-Pb
group (PbB 56 Ug/dL)
0.1% Pb acetate in drinking
water from GD 14 to
parturition
Pb nitrate dissolved in NaCl
solution, administered
intravenously, via caudal vein
at dose levels of 100, 150,
200 mg/kg; one time exposure
onGD9
7500 ppm Pb acetate in
drinking water for 9 wks
PbB 0.6 to <2.0 |ig/dL or
>2.0-13 ug/dL
PbB 0.6 to <2.0 ug/dL or
>2.0-13 ug/dL
PbB 54 ug/dL (39-82 ug/dL)
Mean maternal PbB 37 ug/dL
(22-82 Ug/dL)
24 (22-26) ug/dL (low dose)
40 (35^16) ug/dL (mid dose)
56 (43-82) ug/dL (high dose)
PbB 73 ug/dL
PbB levels at birth in the
exposure groups for these
studies were >180 ug/dL
Maternal PbB >300 ug/dL
Offspring PbB >220 ug/dL
-------
Table AX5-4.1 (cont'd). Effect of Lead on Reproduction and Development in Mammals Effects on Offspring
X
to
Citation
Pinon-
Lataillade
et al. (1995)
Pillai and
Gupta (2005)
Ronis et al.
(1996)T
Ronis et al.
(1998a)T
Species/
Strain/ Age
Mouse/NMRI,
adult
Rat/Charles
Foster,
200-220 g
Rat/Sprague-
Dawley, 22,
55 days or plug-
positive time-
impregnated
Rat/Sprague-
Dawley, various
ages
Dose/Route/
Form/Duration
0-0.5% Pb acetate in
drinking water exposed to Pb
during gestation until post-
GD60
Subcutaneous injection of
0.05 mg/kg-d Pb acetate for
5-7 days prior to mating
through PND 21
0.6% Pb acetate in drinking
water for various durations:
PND 24-74 (pubertal
exposure), PND 60-74 (post
pubertal exposure); 1 1 males
and females in pubertal
exposure group (10 each in
control pubertal group);
6 males and females post-
pubertal exposure and control
groups
0.6% Pb acetate in drinking
water ad libitum for various
durations: GD 5 to PND 1,
GD 5 to weaning, PND 1 to
weaning
3 control litters, 2 gestation
exposure litters, 2 lactation
exposure litters, 2 gestation
and lactation exposure litters,
2 postnatal litters, 2 chronic
litters (4 male and 4 female
pups per litter)
Endpoint
Pb exposure during gestation reduces litter size; reduced birth weight and growth rates.
Long term exposure of rats (premating, gestational, and lactational) to moderate levels
of Pb acetate (s.c.) resulted in reduced activities of hepatic steroid (E2) metabolizing
enzymes (17-6-hydroxy steroid oxidoreductase and UDP glucuronyl transferase) and
decreased hepatic CYP450 content.
Reduction in serum testosterone levels in male, not female; in female suppression of
circulating E2 (p < 0.05) and LH (p < 0.05); reduction in male secondary sex organ
weight (p < 0.0005); delayed vaginal opening and disrupted diestrous in females
(p < 0.005); increased incidence of stillbirth (2% control vs. 19% Pb) (p < 0.005).
Dose-dependent delay in sexual maturation (delayed vaginal opening) (p < 0.0002)
following prenatal Pb exposure that continued until adulthood (85 days old); reduced
birth weight (p < 0.05), more pronounced among male pups.
Blood Lead Concentration
(PbB)
PbB <4-132 ug/dL
PbB not reported
In utero PbB 250-300 ug/dL
Pre-pubertal PbB 30-60 ug/dL
Post-pubertal PbB 30-60 ug/dL
PbBs in the dams and offspring
in this experiment were
>200 ug/dL.
Group: pup PbB
Naive: ~6 ug/dL
Control: <2 ug/dL
Gest: -10 ug/dL
Lact: ~3 ug/dL
Gest+Lact: -13 ug/dL
Postnatal: -260 ug/dL
Chronic: -287 ug/dL
Ronis et al.
(1998b)T
Rat/Sprague-
Dawley, adult
Pb acetate in drinking water
(0.05% to 0.45% w/v); dams
exposed until weaning,
exposure of pups which
continued until PND 21, 35,
55, or 85; 5 control litters
(0%), 10 low-dose litters
(0.05%), 8 mid-dose litters
(0.15%), 9 high-dose litters
(0.45%); 4 male and 4 female
pups per litter
Prenatal Pb exposure that continues until adulthood (85 days old) delays sexual
maturation in female pups in a dose-related manner (p < 0.05); birth weight reduced
(p < 0.05), more pronounced among male pups; decreased growth rates (p < 0.05) in
both sexes accompanied by decrease in plasma concentrations of IGF 1 through puberty
(p < 0.05) and a significant increase in pituitary and growth hormone during puberty
(p < 0.05).
PbBs in the pups between the
ages of 21 and 85 days were
>100 ug/dL and reached up to
388 ug/dL.
-------
Table AX5-4.1 (cont'd). Effect of Lead on Reproduction and Development in Mammals Effects on Offspring
Citation
Ronis et al.
(1998c)
Ronis et al.
Species/ Dose/Route/
Strain/Age Form/Duration
Rat/Sprague- Pb acetate 0.05, 0. 1 5, or
Dawley, adult 0.45% in drinking water
beginning GD 5 continuing
until PND 21, 35, 55, or 85;
5 control litters (0%),
10 low-dose litters (0.05%),
8 mid-dose litters (0. 15%),
9 high-dose litters (0.45%);
4 male and 4 female pups
per litter
Rat/Sprague- Pb acetate in drinking water
Endpoint
Dose-responsive decrease in birth weight (p <
0.05), and crown-to-rump length
(p < 0.05); dose-responsive delay in sexual maturity in male (p < 0.05) and female
(p < 0.05); neonatal decrease in sex steroids (p
< 0.05); pubertal decrease in
testosterone (male) (p < 0.05) and E2 (female) (p < 0.05); decrease estrous cyclicity at
high dose (p < 0.05).
Dose-dependent decrease of the load of failure
in male (p < 0.05); no difference in
Blood Lead Concentration
(PbB)
Dams: 0, 48,
Pups PND 1:
>120 ug/dL
Pups PND 21:
-237 ug/dL
Pups PND 35:
>278 ug/dL
Pups PND 55:
-380 ug/dL
Pups PND 85:
>214ug/dL
88, or 181 ug/dL
<1, -40, -70, or
<1, >50, >160, or
<1, -22, >70, or
<1, >68, >137, or
<1, >43, >122, or
PbB at 825 ppm was 67-
(2001)T
X
Singh et al.
(1993b)
Watson et al.
(1997)
Dawley,
neonate, male
(100 days) and
female pup
Sant'Ana et al. Rat/Wistar,
(2001) 90 days old
Rat/ITRC,
albino (NOS),
6 wks old
Rat/Sprague-
Dawley, adult
to 825 or 2475 ppm ad
libitum from G'D 4 to GD 55
postpartum; 1 male and
female pup/litter (5 litters per
group) control group, 1 male
and female pup/litter (5 litters
per group) 825 ppm Pb
acetate group, 1 male and
female pup/litter (5 litters per
group) 2475 ppm Pb acetate
group
0.1 and 1% Pb in drinking
water
7 days
250, 500, 1000, and 2000
ppm Pb nitrate in drinking
water from GD 6 to GD 14
Pb in drinking water at
34 ppm from weaning of
mothers through gestation
and weaning of offspring
until birth; 6 pups control
group, 6 pups experimental
group
plasma levels of vitamin D metabolites; reduced somatic growth (p < 0.05),
longitudinal bone growth (p < 0.05), and bone strength during the pubertal period
(p < 0.05); sex steroid replacement did not restore skeletal parameters in Pb exposed
rats; L-Dopa increased plasma IGFi concentrations, rates of bone growth, and bone
strength measures in controls while having no effect in Pb exposed groups; DO gap x-
ray density and proximal new endostreal bone formation were decreased in the
distration gaps of the Pb-treated animals (p < 0.01); distraction initiated at 0.2 mm 30 to
60 days of age.
1% Pb exposure reduced offspring body weight during treatment, no changes observed
after 0.1% exposure; no altered offspring sexual maturation, higher Pb improved sexual
behavior, while 0.1% reduced it; 0.1% Pb caused decrease in testis weight, an increase
in seminal vesicle weight, and no changes in plasma testosterone levels, hypothalamic
VMA levels were increased compared to control group; reduced birth weight and
growth rates.
Significantly reduced litter size, reduced fetal weight, and a reduced crown-to-rump
length, increased resorption and a higher blood-Pb uptake in those groups receiving
1000 and 2000 ppm Pb; these also had a higher placental uptake; however the level was
the same in both groups; fetal Pb uptake remained the same whether or not 2000 ppm
Pb was given to an iron-deficient or normal iron groups of mothers.
Reduced body weight (p = 0.04); parotid function was decreased by nearly 30%
(p = 0.30); higher mean caries scores than the control pups (p = 0.005); pre- and
perinatal Pb exposure had significantly increased susceptibility to dental caries
(p = 0.015).
192 ug/dL
PbB at 2475 ppm was 120-
388 ug/dL
PbB 36.12 — 9.49ug/dLor
13.08 ± 9.42 ug/dL
PbB not reported
PbB 48 ± 13 ug/dL
-------
Table AX5-4.1 (cont'd). Effect of Lead on Reproduction and Development in Mammals Effects on Offspring
Citation
Wiebe et al.
(1998)
Species/
Strain/ Age
Rats/Sprague-
Dawley, adult
Dose/Route/
Form/Duration
20 or 200 ppm Pb chloride in
drinking water; prior to
pregnancy, during pregnancy,
lactation
Endpoint
Exposure to Pb did not affect tissue weights but did cause a significant decrease in
gonadotropin-receptor binding in the prepubertal, pubertal, and adult females;
conversion of progesterone to androstenedione and dihydrotestosterone was
significantly decreased in 21 -day old rats, in 150-day old females, the exposure to Pb
resulted in significantly increased conversion to the 5-alpha-reduced steroids, normally
high during puberty.
Blood Lead Concentration
(PbB)
PbB4.0± 1.4 to 6.6 ±
2.3 ug/dL
*Not including effects on the nervous or immune systems.
t Candidate key study.
cGMP, cyclic guanosine—3',5'-monophosphate; DO, distraction osteogenesis; DOPAc, 3,4-dihydroxyphenylacetic acid; E2, estradiol; ERG, electroretinographic; FSH, follicle stimulating hormone;
GD, gestational day; IGF!, insulin-like growth factor 1; i.v., intravenous; kDA, kilodalton; LH, luteinizing hormone; NOS, not otherwise specified; PbB, blood Pb concentration; PDE,
phosphodiesterase; PND, post-natal day; p.o., per os (oral administration); s.c., subcutaneous; SEM, standard error mean; UDP, uridine diphosphate; VMA, vanilmandelic acid
X
-------
Table AX5-4.2. Effect of Lead on Reproduction and Development in Mammals Effects on Males
X
Citation
Acharya et al.
(2003)
Adhikari et al.
(2000)
Adhikari et al.
(2001)
Alexaki et al.
(1990)
Al-Hakkak
et al. (1988)
Barratt et al.
(1989)
Bataineh et al.
(1998)
Batra et al.
(2001)
Batra et al.
(2004)
Bizarro et al.
(2003)
Boscolo et al.
(1988)
Species/
Strain/Age
Mouse/Swiss,
6-8 wks old
Rat/Druckrey,
28 days old
Rat/Druckrey,
28 days old
Bulls/Holstein,
3-5 yrs old
Mouse/
BALB/c,
weaning
Rat/Wistar,
70 days old
Rat/Sprague-
Dawley, adult
Rat/Portan,
8 wks old
Rat/Portan,
8 wks old
Mouse/CD-I,
adult
Rat/Sprague-
Dawley,
weanling
Dose/Route/Form/Duration
200 mg/kg Pb acetate through
i.p. injection of Pb; one time
injection
0.0, 0.4, 4.0, 40.0 uM Pb
acetate in vitro for 24 and
48 hr
5, 10, and 20 mg/kg Pb in
distilled water by gavage for
2 wks
In vitro fertilization 2.5 or
0.25 ug/mL
0, 25, 50 mg Pb monoxide
alloy/kg in chow for 35-
70 days
0, 0.3, 33, 330 mg Pb
acetate/kg-d in drinking
water, by gavage for 63 days
1000 ppm Pb acetate in
drinking water for 12 wks
10, 50, 200 mg/kg Pb acetate
orally for 3 mo
10, 50, 200 mg/kg Pb acetate
orally for 3 mo
0.01 M Pb acetate twice a
week for 4 wks
60 mg Pb acetate/mL in
drinking water for 1 8 mo
1 ml point
Testicular weight loss with constant increase in the incidence of abnormal sperm
population; decrease in sperm count; testicular ascorbic acid also declined significantly;
significant rise in LPP of tissue; LPP is indicative of oxidative stress in treated mice
testes.
Germ cells progressively detached from Sertoli cell monolayer into medium in a
concentration and duration dependent manner Viability of the detached cells showed a
decrease with increase in time and concentration of Pb; leakage of LDH recorded at
higher dose of 4.0 and 40.0 uM.
Induced significant numbers of germ cells to undergo apoptosis in the semiferous
tubules of rats treated with highest dose; DNA fragmentation was not detected at any of
the doses; level of Pb accumulation in testes increased in a dose-dependent manner.
Sperm motility reduced significantly at 2. 5 ug/mL; lower concentration had no effect
on sperm motility.
Reduced number of spermatogenia and spermatocytes in the 50 mg group after 70 days;
reduced number of implantations after mating (after 35 days exposure).
Increased number of abnormal post-testicular sperm in the highest exposure group;
reduced number of spermatozoa at PbB >4.5 ug/dL.
Fertility was reduced in males.
Pb in testis and epididymis increased with dose; administration of zinc reduced Pb
levels; dose related changes in activities of enzyme alkaline phosphatase and Na+-K+-
ATPase, which decreased with increased dose of Pb; improvement in activities of
enzymes was seen in groups given Pb and zinc; disorganization and disruption of
spermatogenesis with accumulation of immature cells in lumen of tubule; highest dose
of Pb resulted in arrest of spermatogenesis, and decrease in germ cell layer population;
highest dose levels, damage of basement membrane, disorganization of epithelium and
vacuolization cells; tubules were found almost empty, indicating arrest of
spermatogenesis.
LH and FSH concentrations were decreased at 200 mg/kg; decrease in fertility status at
200 mg/kg; decline in various cell populations at 200 mg/kg; 50 mg/kg group hormone
levels, cell numbers, and fertility status were found close to normal.
Dose-time relationship was found; ROS role.
Increased vacuolization in Sertoli cells; no other ultrastructural modifications; no
impairment of spermatogenesis.
Blood Lead Concentration
(PbB)
Not reported
PbB not applicable-in vitro study
PbB not reported
PbB not applicable-in vitro study
PbB not reported
PbB 2, 4.5, 7, 80 ug/dL
PbBs >40 ug/dL
PbB not reported
PbB not reported
PbB not reported
PbB not reported
PbB 4-17 ug/dL
-------
Table AX5-4.2 (cont'd). Effect of Lead on Reproduction and Development in Mammals Effects on Males
X
Citation
Chowdhuri
etal. (2001)
Chowdhury
et al. (1984)
Chowdhury
et al. (1986)
Chowdhury
et al. (1987)
Species/
Strain/Age
Mouse/
BALB/c,
3 mo old
Rat/ Albino,
(NOS), adult
Rat/NOS, adult
Rat/Charles
Foster,
150±5g
Dose/Route/Form/Duration
0.0,0.2,0.5, 1.0, 2.0ug/mL
Pb acetate in culture medium
for 2 hr (superovulated ova
and sperm)
Dietary concentrations of
0.25, 0.50, or 1.0 g/L Pb
acetate for 60 days
0, 1, 2, 4, 6 mg Pb
acetate/kg-d i.p.
for 30 days
0, 1, 2, 4, 6 mg Pb
acetate/kg-d/i.p.
for 30 days
1 ml point
Significant dose dependent decrease in the number of sperm attaching to the ova in both
exposed groups; decrease in the incorporation of radio-labeled thymdine, uridine, and
methionine.
Testicular atrophy along with cellular degeneration was conspicuous at 1 g/L; high
cholesterol concentration and significantly low ascorbic acid concentration were found
in the testes at 1 g/L; lowest dose (0.25 g/L) had no significant morphological and
biochemical alterations, whereas as 0. 5 g/L resulted in partial inhibition of
spermatogenesis.
Dose-related decrease of testis weight; at 187 ug/dL: degenerative changes in testicular
tissues; at 325 ug/dL: degenerative changes and inquiry of spermatogenetic cells;
edematous dissociation in interstitial tissue.
Dose related decrease of testis weight at 56 |_lg of spermatoids; at 91 ug/dL: inhibition
of post-meiotic spermatogenic cell; at 196 ug/dL: decreased spermatogenic cell count
(6), detachment of germinal call layers; at 332 ug/dL: Decreased spermatogenic cell
Blood Lead Concentration
(PbB)
PbB not applicable-in v
PbB 54-143 ug/dL
PbB 20, 62, 87, 187, or
325 ug/dL
PbB 56-3332 ug/dL
itro study
Coffigny et al. Rat/Sprague-
(1994)T Dawley, adult
Corpas et al. Rat/Wistar,
(1995) adult
Corpas et al. Rat/Wistar,
(2002a) adult
Corpas et al. Rat/Wistar,
(2002b) adult
Inhalation exposure to
5 mg/m3 Pb oxide daily for
13 days during gestation
(GD 2, 3, 6-10, 13-17, 20)
300 mg/L Pb acetate via
drinking water beginning GD
1 through 5 days postnatal or
throughout gestation and
early lactation
300 mg/L acetate Pb in
drinking water beginning at
mating until PND 12 and 21
300 mg/L acetate Pb in
drinking water beginning at
mating until PND 12 and 21
count, degenerative changes, Interstitial edema, and atrophy of Leydig cells.
Adult male offspring exhibit no change in sperm parameters or sex hormones T, FSH,
and LH (because of duration or timing).
Testicular weight and gross testicular structure were not altered; seminiferous tubule
diameter and the number of prospermatogonia were reduced; total DNA, RNA, and
protein content of the testes in treated rats was significantly reduced, DNA: RNA ratio
remained unaltered.
Neither abnormalities in the liver structure nor depositions of Pb, toxicant produced
biochemical alterations; pups exhibited decrease in hemoglobin, iron and alkaline, and
acid phosphatase levels and an increase in Pb content; protein, DNA, and lipid total
amounts were reduced, and hepatic glycogen content was diminished at 12 and 21 PN,
with a higher dose of glucose in blood; decrease in alkaline phosphatase in liver of pups
at day 21 PN, but acid phosphatase was unaltered.
Neither abnormalities in the liver structure nor depositions of Pb, toxicant produced
biochemical alterations; pups exhibited decrease in hemoglobin, iron and alkaline, and
acid phosphatase levels and an increase in Pb content; protein, DNA, and lipid total
amounts were reduced, and hepatic glycogen content was diminished at 12 and 21 PN,
with a higher dose of glucose in blood; decrease in alkaline phosphatase in liver of pups
at day 21 PN, but acid phosphatase was unaltered.
PbB 71.1 ug/dL (dam)
PbB 83.2 ug/dL (fetal)
PbB 14 ug/dL
PbB 22 ug/dL
PbB 22 ug/dL
-------
Table AX5-4.2 (cont'd). Effect of Lead on Reproduction and Development in Mammals Effects on Males
Citation
Cory-Slechta
et al. (2004)T
Foote (1999)
Foster et al.
(1993)
Foster et al.
(1996a)
Foster et al.
(1998)
Gandley et al.
(1999)
Gorbel et al.
(2002)
Species/
Strain/Age
Rat/Long-Evans,
adult
Rabbit/Dutch-
belted, adult
Monkey/
Cynomolgus,
adult
Monkey/
Cynomolgus,
adult
Monkey/
Cynomolgus,
adult
Rat/Sprague-
Dawley, adult
Rat/(NOS),
90 days old
Dose/Route/Form/Duration
Pb acetate in drinking water
beginning 2 mo before
breeding until the end of
lactation
0, 0.005, 0.01, and 0.025 mM
PbC12 in vitro; one time dose
0-1500 |lg Pb acetate/kg-d in
gelatin capsules p.o. for
various durations: 9 control
monkeys, 4 monkeys in
lifetime group (birth to 9 yrs),
4 in infancy group (first
400 days of life), 4 in post-
infancy exposure (from
300 days to 9 yrs)
0-1500 |lg Pb acetate/kg-d in
gelatin capsules p.o. from
birth until 9 yrs of age:
8 control monkeys, 4
monkeys in low group
(6-20 ug/dL), 7 monkeys in
high group (22-148 Ug/dL)
0-1500 |lg Pb acetate/kg-d in
gelatin capsules p.o. for
various durations: birth to
10 yrs (lifetime); PND 300 to
10 yrs (post-infancy); birth to
300 days (infancy); 3 control
monkeys, 4 lifetime,
4 infancy, 5 post-infancy
Male rats received Pb acetate
25 or 250 ppm in drinking
water for 35 days prior to
mating
3mg(Pl)or6mg(P2)Pb
acetate in drinking water for
15, 30, 45, 60, or 90 days
1 ml point
Observed potential effects of Pb and stress in female; Pb alone (in male) and Pb plus
stress (in females) permanently elevated corticosterene levels in offspring.
Six out of 22 males tested showed appreciable spontaneous hyperactivation, Pb did not
affect hyperactivation, or associated capacitation.
Suppressed LH response to GnRH stimulation in the lifetime group (p = 0.0370);
Sertoli cell function (reduction in the inhibin to FSH ratio) (p = 0.0286) in lifetime and
post-infancy groups.
Mean PbB of 56 ug/dL showed no significant alterations in parameters of semen
quality (count, viability, motility, or morphology).
Circulating concentrations of FSH, LH, and testosterone were not altered by treatment;
semen characteristics (count, motility, morphology) were not affected by treatment
possibly because not all Sertoli cells were injured; degeneration of seminiferous
epithelium in infancy and lifetime groups (no difference in severity between these
groups); ultrastructural alterations in seminal vesicles, most prominent in infancy and
post-infancy groups.
High dose reduced fertility; low dose altered genomic expression in offspring.
Male rats, absolute and relative weights of testis, epididymis, prostate and seminal
vesicles were found to significantly decrease at day 15 in P2 group and at day 45 in PI
group, at day 60 these absolute values and relative weights returned to control values; at
day 15 arrest of cell germ maturation, changes in the Sertoli cells, and presence of
apoptotic cells were observed; serum testosterone level was found to be lowered at day
15 inbothPl and P2, and peaked at day 60, then returned to normal values.
Blood Lead Concentration
(PbB)
PbB 30-40 ug/dL
PbB not applicable-in vitro study
Lifetime group 3—26 ug/dL at
4—5 yrs; infancy group
5-36 ug/dL at 100-300 days,
3—3 ug/dL at 4—5 yrs; post-
infancy group 20—35 ug/dL
PbB 10 ± 3 or 56 ± 49 ug/dL
PbB -35 ug/dL
PbB 15-23 ug/dL or
27-60 ug/dL
PbB not reported
-------
Table AX5-4.2 (cont'd). Effect of Lead on Reproduction and Development in Mammals Effects on Males
X
oo
Citation
Graca et al.
(2004)
Hsu et al.
(1997)
Hsu et al.
(1998a)
Hsu et al.
(1998b)
Huang et al.
(2002)
Johansson
(1989)
Johansson and
Pellicciari
(1988)
Johansson and
Wide (1986)
Species/
Strain/Age
Mouse/CD-I,
2 mo old
Rat/Sprague-
Dawley, 7 wks
old
Rat/Sprague-
Dawley,
100-120 g
Rat/Sprague-
Dawley, 7 wks
old
Mouse MA- 10
cells
Mouse, 9 wks
old
Mouse/NMRI,
9 wks old
Mouse/NMRI,
9 wks old
Dose/Route/Form/Duration
Subcutaneous injection of
74 mg/kg-d of Pb chloride for
1 to 3 days
10 mg/kg Pb acetate through
i.p. injection to males for 6 or
9 wks
20 or 50 mg Pb acetate via
i.p. route weekly to males for
6 wks
10 mg/kg Pb acetate weekly
via i.p. injection to males for
6 wks
10~8 to 10~5 M Pb incubated
for 3 hr
0-1 g Pb chloride/L in
drinking water for 112 days
1 g/L Pb chloride in drinking
water for 16 wks
0-1 g/L Pb chloride in
drinking water for 84 days
1 ml point
Reversible changes in sperm (count) and ultrastructural changes in testes (reduced
diameter of seminiferous tubules).
Six- week group had unchanged epididymal sperm counts, percent of motile sperms, and
motile epididymal sperm counts compared with control group; 9-wk group showed
statistically lower epididymal sperm counts, and lower motile epididymal sperm counts;
good correlation between blood Pb and sperm Pb; significantly higher counts of
chemiluminescence, they were positively associated with sperm Pb level; epididymal
sperm counts, motility, and motile epididymal sperm counts were negatively associated
with sperm chemiluminescence; SOPR were positively associated with epididymal
sperm counts, motility and motile epididymal sperm counts, sperm chemiluminescence
was negatively associated with SOPR.
Serum testosterone levels were reduced; percentage of capacitation and the
chemiluminescence were significantly increased in fresh cauda epididymal
spermatozoa; serum testosterone levels were negatively associated with the percentage
of acrosome-reacted spermatozoa; sperm chemiluminescence was positively correlated
with the percentage of both capacitated and acrosome-reacted spermatozoa; SOPR was
negatively associated with the percentage of both capacitated and acrosome-reacted
spermatozoa.
Intake of VE and/or VC in Pb exposed rats prevented the Pb associated sperm ROS
generation, increased the epididymal sperm motility, enhanced the capacity of sperm to
penetrate eggs harvested from unexposed female rats in vitro; protective effect of VE
and VC not associated with reduced blood or sperm Pb levels.
Higher decreases in human chorionic gonadotropin (hCG)-stimulated progesterone
production, expressions of StAR protein, and the activity of 36-HSD compared to 2 hr;
no affect on P450scc enzyme activity.
No effects on frequency of motile spermatozoa, nor on swimming speed; decreased
fertilizing capacity of the spermatozoa by in vitro fertilization; premature acrosome
reaction .
Decreased uptake of PI was found in spermatozoa from the vas deferens of the Pb-
exposed mice; after thermal denaturation of the DNA, the spermatozoa showed a higher
uptake of PI in comparison to those of the controls; after reductive cleavage of S-S
bonds with DTT and staining with a thiol-specific reagent significantly fewer reactive
disulfide bonds were also observed in the spermatozoa; significant delay in the capacity
for NCD was noted.
No effects on sperm count; no effects on serum testosterone; reduced number of
implantations after mating.
Blood Lead Concentration
(PbB)
PbB not reported
PbB after 6 wks 32 ug/dL, after
9 wks 48 ± 4.3 ug/dL
PbBs >40 ug/dL
PbB 30.1 ±3.4 to 36.1 ±4.6
PbBs >40 ug/dL
PbB not applicable-in vitro study
PbB 0.5-40 ug/dL
PbB 42 ± 1.6 ug/dL
PbB <0.5-32 ug/dL
Mean tissue Pb content
difference between Pb treated
and controls: testicular 11 ug/g
(epididymal 67 ug/g)
PbB <0.5 ug/100 mL
-------
Table AX5-4.2 (cont'd). Effect of Lead on Reproduction and Development in Mammals Effects on Males
X
Citation
Johansson
etal. (1987)
Kempinas
etal. (1988)
Kempinas
etal. (1990)
Kempinas
etal. (1994)
Klein et al.
(1994)
Liu et al.
(2001)
Liu et al.
(2003)
Species/
Strain/Age
Mouse/NMRI,
9-10 wks old
Rat/Wistar,
adult
Rat/NOS,
pubertal
Rat/Wistar,
50 days old
Rat/Sprague-
Dawley,
100 days old
Mouse,
MA- 10 cells
Mouse,
MA- 10 cells
Dose/Route/Form/Duration
1 g/L Pb chloride in drinking
water for 16 wks
0.5 g/L and 1.0 g/L Pb acetate
in drinking water for 90 days
(1.0 g/L) Pb acetate in
drinking water in addition to
i.v. injections of Pb acetate
(O.lmg/100gbw)every
10 days, 20 days
(1.0 g/L) Pb acetate in
drinking water in addition to
i.v. injections of Pb acetate
(O.lmg/lOOgbw) every
1 5 days, 9 mo
0-1 g Pb acetate/L in
drinking water + 0.1 mg/kg
i.v. every 10 days for 20 days
0-1 g Pb acetate/L in
drinking water + 0.1 ug/kg
i.v. every 15 days for
270 days
0.1, 0.3, or 0.6% Pb acetate in
distilled water for 2 1 days
10~8 to 10~5 Pb acetate in
vitro for 2 hr
10~8to 10"5 Pb acetate in
vitro for 6 hr incubated
1 ml point
Spermatozoa had significantly lower ability to fertilize mouse eggs; morphologically
abnormal embryos were found.
PbB exhibited a significant increase in both groups; decrease in hematocrit and
hemoglobin, together with a rise in glucose levels; no signs of lesion were detected
upon histological examination of testes, caput, and cauda epididymidis; an increase in
ductal diameter, and a decrease in epithelial height were observed in the cauda
epididymidis; concentration of spermatozoa stored in the caudal region of the
epididymis exhibited a significant increase in Pb-treated animals.
Basal levels of testosterone were higher both in the plasma and in the testes of acutely
intoxicated animals; levels of LH were not affected in either group, nor was the LHRH
content of the median eminence; density of LH/hCG binding sites in testicular
homogenates was reduced by saturnism in both groups, apparent affinity constant of the
hormone-receptor, complex significantly increased.
Increased plasma and testicular testosterone concentrations; no effects on testicular
weight; reduced weight of prostate; increased weight of seminal vesicle and seminal
secretions.
2— 3-fold enhancement of mRNA levels of GnRH and the tropic hormone LH; 3-fold
enhancement of intracellular stores of LH; mRNA levels of LH and GnRH and pituitary
levels of stored LH are proportional to blood levels of Pb.
Significantly inhibited hCG- and dbcAMP-stimulated progesterone production in
MA-10 cells; steroid production stimulated by hCG or dbcAMP were reduced by Pb;
expression of StAR protein and the activities of P450 side-chain cleavage (P450) and
36-HSD enzymes detected; expression of StAR protein stimulated by bdcAMP was
suppressed by Pb at about 50%; progesterone productions treated with 22R-
hydroxycholesterol or pregnenolone were reduced 30^10% in Pb treated MA-10 cells.
Pb significantly inhibited hCG- and dbcAMP-stimulated progesterone production from
20 to 3 5% in MA- 1 0 cells at 6 hr; Pb suppressed the expression of steriodogenesis acute
regulatory (StAR) protein from 30 to 55%; activities P450 side-chain cleavage
(P450scc) enzyme and 36-HSD were reduced by Pb from 15 to 25%.
Blood Lead Concentration
(PbB)
PbB not reported
PbB 65-103 ug/dL
PbB -40 ug/dL
PbB 10-41 ug/dL
PbB 8.5^10 ug/dL
PbB 42-102 ug/dL
PbB not applicable-in vitro study
PbB not applicable-in vitro study
-------
Table AX5-4.2 (cont'd). Effect of Lead on Reproduction and Development in Mammals Effects on Males
X
I
o
Citation
Marchlewicz
et al. (1993)
McGivern
etal. (1991)T
McMurry
et al. (1995)
Mishra and
Acharya
(2004)
Moorman
et al. (1998)
Murthy et al.
(1991)
Murthy et al.
(1995)
Nathan et al.
(1992)
Pace et al.
(2005)
Piasecka et al.
(1995)
Species/
Strain/Age
Rat/Wistar,
90 days old
Rat/Sprague-
Dawley, adult
Rat/Cotton,
adult
Mouse/Swiss,
9-10 wks old
Rabbit/NOS,
adult
Rat/ITRC,
(NOS),
weanling
Rat/Druckrey,
adult
Rat/Sprague-
Dawley, adult
Mouse/BALB/c,
adult
Rat/Wistar,
adult
Dose/Route/Form/Duration
0-1% Pb acetate in drinking
water for 270 days
0. 1% Pb acetate in drinking
water from GD 14 to
parturition: 8 control litters;
6 Pb acetate litters (5 males
per litter)
0, 100, or 1000 ppm Pb in
drinking water for 7 or
13 wks
10 mg/kg Pb acetate in
drinking water for 5 to 8 wks
3.85 mg/kg Pb acetate
subcutaneous injection for
15 wks
0-250 ppm Pb acetate in
drinking water for 70 days
Pb 5 mg/kg i.p. Pb acetate in
drinking water for 16 days
0,0.05, 0.1,0.5, or 1% Pb
acetate in drinking water for
70 days
0. 1 ppm Pb acetate in
drinking water (lactational
exposure as neonates and
drinking water from PND 2 1
to PND 42)
1% aqueous solution of Pb
acetate for 9 mo
1 ml point
No histological or weight changes in testicle or epididymis; fever spermatozoa in all
zones of the epididymis.
Decreased sperm count (21% at 70 days and 24% at 165 days; p < 0.05); reduced male
behavior (p < 0.05); enlarged prostate (25% increase in weight; p < 0.07); irregular
release patterns of both FSH and LH (p < 0.05).
Immune function was sensitive to Pb exposure; spleen mass was reduced in cotton rats
receiving 100 ppm Pb; total leukocytes, lymphocytes, neutrophils, eosinophils, total
splenocyte yield, packed cell volume, hemoglobin, and mean corpuscular hemoglobin
were sensitive to Pb exposure; reduced mass of liver, seminal vesicles, and epididymis
in males after 7 wk exposure.
Stimulates lipid peroxidation in the testicular tissue, associated with increased
generation of noxious ROS; reduced sperm count, increased sperm abnormality
Increased blood levels associated with adverse changes in the sperm count, ejaculate
volume, percent motile sperm, swimming velocities, and morphology; hormonal
responses were minimal; dose-dependent inhibition of sperm formation; semen quality,
threshold estimates ranged from 16 to 24 ug/dL.
At 20 ug/dL no impairment of spermatogenesis; vacuolization of Sertoli cell cytoplasm
and increase in number and size of lysosomes.
Swelling of nuclei and acrosomes round spermatids; in Sertoli cells, nuclei appeared
fragmented, whereas the cytoplasm exhibited a vacuolated appearance and a few
structures delimitated by a double membrane that contains microtubules arranged in
parallel and cross-striated fin fibrils, cell tight junction remain intact; no significant
change in epididymal sperm motility and counts, testicular blood levels were found to
be elevated after Pb exposure.
No effects on spermatogenesis in all groups; at 124 ug/dL: decreased seminal vesicle
weight; decreased serum testosterone in the 0.5% group at 10 wks; no effects in the
other exposure categories; no effects on serum FSH, LH, nor pituitary LH content.
Reduction in fertility when mated with unexposed females; no change in sperm count;
increase in number of apoptotic cells intestes.
Pb-loaded (electron dense) inclusions were found in the cytoplasm of the epididymal
principal cells, especially in the caput of epididymis, also present, but smaller, in
smooth muscle cells; inclusions were located in the vacuoles, rarely without any
surrounding membrane; similar Pb-containing structures were found in the epididymal
lumen.
Blood Lead Concentration
(PbB)
PbB not reported
Control PbB <5 ug/dL at birth
Maternal PbB 73 ug/dL at birth
Pup PbB 64 ug/dL at birth
PbB not reported
PbB not reported
PbB 0, 20, 40, 50, 70, 80, 90, and
110 ug/dL
PbB 20.34 ± 1.79 ug/dL
PbB 7.39 ug/dL
PbB 2.3, 40, 44, 80, or 124 ug/dL
Neonatal PbB 59.5 ug/dL
Post PND 21 PbB 20.3 ug/dL
PbB not reported
-------
Table AX5-4.2 (cont'd). Effect of Lead on Reproduction and Development in Mammals Effects on Males
Citation
Species/
Strain/Age
Dose/Route/Form/Duration
1 ml point
Blood Lead Concentration
(PbB)
>
X
Piasek and Rat/Albino,
Kostial (1987) (NOS), adult
Pinon- Rat/Sprague-
Lataillade Dawley,
et al. (1993) 90 days old
Pinon-
Lataillade
et al. (1995)
Rodamilans
et al. (1988)
Ronis et al.
(1996)T
Ronis et al.
(1998a)
Mouse/NMRI,
adult
Mouse/BALB/c,
63 days old
Rat/Sprague-
Dawley, adult
Rat/Sprague-
Dawley, adult
1500, 3500, and 5500 ppm of
Pb acetate in drinking water
for 18 wks
0-0.3% Pb acetate in
drinking water for 70 days
5 mg/m Pb oxide in aerosol
for 6 hr/day, 5 days/wk,
90 days
0-0.5% Pb acetate in
drinking water, day 1 of
gestation until 60 days of age
0-366 mg Pb acetate/L in
drinking water for 30, 60, 90,
120, 150, 180 days
0.6% Pb acetate in drinking
water for various durations:
PND 24-74 (pubertal
exposure); PND 60-74 (post
pubertal exposure); 11 males
and females in pubertal
exposure group (10 each in
control pubertal group);
6 males and females post-
pubertal exposure and control
groups
0.6% Pb acetate in drinking
water ad libitum for various
durations as follows: GD 5 to
PND 1;GD 5 to weaning;
PND 1 to weaning; 3 control
litters, 2 gestation exposure
litters, 2 lactation exposure
litters, 2 gestation and
lactation exposure litters,
2 postnatal exposure litters,
2 chronic exposure litters;
4 male and 4 female pups
per litter.
No overt signs of general toxicity in adult female rats, only at the end of the exposure
period the mean body weight of males exposed to two higher levels was slightly lower;
no effect of Pb exposure on male fertility either after first or after second mating; values
in the pups did not differ from control group.
Decreased weight of seminal vesicles in inhalation study; no effects on spermatogenesis
(epididymal sperm count, spermatozoal motility or morphology) or plasma testosterone,
LH, and FSH; no effects on fertility; decrease in epididymal sperm count of progeny of
sires of the inhalation group, however without effect on their fertility.
No effects on testicular histology, nor on number and morphology of epididymal
spermatozoa; no effects on plasma FSH, LH, and testosterone, nor on testicular
testosterone; decreased weight of testes, epididymis, seminal vesicles, and ventral
prostate; no effects on fertility.
Reduction of intratesticular testosterone concentrations after 30 days; reduction of and
renostenedione concentrations after 150 days; no changes in intratesticular progesterone
and hydroxy-progesterone.
PbB > 250 ug/dL reduced circulating testosterone levels in male rats 40-50%
(p < 0.05); reduction in male secondary sex organ weight (p < 0.005); delayed vaginal
opening (p < 0.0001); disrupted estrous cycle in females (50% of rats); increased
incidence of stillbirth (2% control vs. 19% Pb) (p < 0.005).
Suppression of adult mean serum testosterone levels was only observed in male pups
exposed to Pb continuously from GD 5 throughout life (p < 0.05).
PbB not reported
PbB 58 ± 1.7 ug/dL (oral)
PbB51.1± 1.8ng/dL
(inhalation)
PbB <4-132 ug/dL
PbB 48-67 ug/dL
Pubertal PbB 30-60 ug/dL
Post pubertal PbB 30-60 ug/dL
Mean PbBs in male rats 30—
60 ug/dL, respectively
Group: male PbB
Naive: 5.5 ± 2.0 ug/dL
Control: 1.9 ±0.2 ug/dL
Gest: 9.1 ±0.7 ug/dL
Lact: 3.3 ± 0.4 ug/dL
Gest±Lact: 16.1 ± 2.3 ug/dL
Postnatal: 226.0 ± 29 ug/dL
Chronic: 316.0 ± 53 ug/dL
-------
Table AX5-4.2 (cont'd). Effect of Lead on Reproduction and Development in Mammals Effects on Males
Citation
Species/ Strain/Age Dose/Route/Form/Duration
1 ml point
Blood Lead Concentration
(PbB)
Ronis et al.
(1998b)
Ronis et al.
(1998c)T
>
X
to
Sant'Ana
etal. (2001)
Saxena et al.
(1984)
Saxena et al.
(1986)
Saxena et al.
(1987)
Rat/Sprague-
Dawley, adult
Rat/Sprague-
Dawley, adult
Rat/Wistar, 90 days
old
Rat/ITRC, albino
(NOS), 12 wks old
Rat/ITRC, albino
(NOS), 40-50 g
Rat/Wistar, 40-50 g
Pb acetate in drinking water
(0.05% to 0.45% w/v); dams
exposed until weaning,
exposure of pups which
continued until PND 21, 35,
55, or 85; 5 control litters
(0%), 10 low-dose litters
(0.05%), 8 mid-dose litters
(0.15%), 9 high-dose litters
(0.45%); 4 male and 4 female
pups per litter
Pb acetate 0.05, 0.15, or
0.45% in drinking water
beginning GD 5 continuing
until PND 21, 35, 55, or 85;
5 control litters (0%), 10 low-
dose litters (0.05%), 8 mid-
dose litters (0.15%), 9 high-
dose litters (0.45%); 4 male
and 4 female pups per litter
0.1 and 1% Pb acetate in
drinking water for 7 days
8 mg/kg Pb acetate i.p. for
15 days
5, 8, or 12 mg Pb+2/kg Pb
acetate i.p. for 15 days
8 mg Pb2/kg-d Pb acetate i.p.
for 100 days (from PND 21 to
PND 120)
Dose-response reduction in birth weight (p < 0.05), more pronounced in male pups;
decreased growth rates in both sexes (p < 0.05) were accompanied by a statistically
significant decrease in plasma concentrations of IGF 1 through puberty PND 35 and
55 (p < 0.05); increase in pituitary growth hormone during puberty (p < 0.05).
Dose-responsive decrease in birth weight (p < 0.05); dose-responsive decrease in
crown-to-rump length (p < 0.05); dose-dependent delay in sexual maturity (p < 0.05);
decrease in prostate weight (p < 0.05); decrease in plasma concentration of
testosterone during puberty (p < 0.05); decrease in plasma LH (p < 0.05); elevated
pituitary LH content (p < 0.05); decrease in plasma testosterone/LH ratio at high dose
(p < 0.05).
0.1% Pb caused decrease in testis weight, an increase in seminal vesicle weight and
no changes in plasma testosterone levels, hypothalamic VMA levels were increased
compared to control group.
Histoenzymic and histological alterations in the testes; degeneration of seminiferous
tubules; patchy areas showing marked loss in the activity of succinic dehydrogenase
and adenosine triphosphatase, whereas alkaline phosphatase activity showed only
slight inhibition.
Increasing dose of Pb resulted in significant loss of body weight, as well as testicular
weight in groups 3 and 4; cholesterol in the testis of rats markedly decreased at all
given doses of Pb and was statistically significant in groups 3 and 4; in phospholipid
contents, the significant decrease was observed only at two highest doses, while at the
lowest dose the decrease was not significant; activity of ATPase remained unaffected
at all three doses of Pb; no significant increase in Pb content in the testis was noticed
at lower dose levels as compared to control; however, significant increase was found
in groups 3 and 4 which was dose dependent.
Disturbed spermatogenesis; Leydig cell degeneration; altered enzyme activity
(G6PDH).
Mean PbB in offspring at 0.05%
(w/v) 49 ± 6 ug/dL
Mean PbB in offspring at 0.15%
(w/v) 126 ± 16 ug/dL
Mean PbB in offspring at 0.45%
(w/v) 263 ± 28 ug/dL
Dams: 0, 48,
PupsPNDl:
120 ug/dL
PupsPND21:
236 ug/dL
Pups PND 35:
278 ug/dL
Pups PND 55:
379 ug/dL
Pups PND 85:
214 ug/dL
88, or 181 ug/dL
<1, 40, 83, or
<1, 46, 196, or
<1, 20, 70, or
<1, 68, 137, or
<1, 59, 129, or
PbB 36.12 ±9.49 ug/dL and
13.08 ± 9.42 ug/dL
PbB not reported
PbB not reported
PbB not reported
-------
Table AX5-4.2 (cont'd). Effect of Lead on Reproduction and Development in Mammals Effects on Males
>
X
Citation
Saxena et al.
(1990)
Singh et al.
(1993a)
Sokol (1987)
Sokol (1989)
Sokol (1990)
Sokol and
Berman
(1991)
Species/Strain/Age
ITRC albino,
(NOS), adult
Monkey/
Cynomolgus, birth
Birth:
300 days:
Rat/Wistar, 52 days
old
Rat/Wistar, 27 days
old
52 days old
Rat/Wistar, 52 days
old
Rat/Wistar, NOS
Dose/Route/ Form/Duration
8 mg/kg/d Pb acetate for
45 days
0-1500 |lg Pb acetate/kg-d in
gelatin capsules for various
durations: 3 control
monkeys, 4 monkeys in
infancy group (exposure first
400 days), 5 in post-infancy
group (exposure 300 days to
9 yrs of age), 4 in lifetime
group (exposure from birth
until 9 yrs)
0-0.3% Pb acetate in
drinking water for 30 days
0-0.6% Pb acetate in
drinking water for 30 days +
30 days recovery
0-0.6% Pb acetate in
drinking water for 30 days +
30 days recovery
0-0.6% Pb acetate in
drinking water for 7, 14, 30,
60 days
0, 0.1, or 0.3% Pb acetate in
drinking water for 30 days
beginning at 42, 52, or
70 days old; 8—11 control rats
for each age, 8—1 1 rats for
each age in 0.1% group, 8—
1 1 rats for each age in 0.3%
group
1 ml point
Alterations in SDH, G6PDH activity, cholesterol, and ascorbic acid contents and
reduced sperm counts associated with marked pathological changes in the testis,
after combined treatment with Pb and immobilization stress in comparison to either
alone.
Degeneration of seminiferous epithelium in all exposed groups (frequency not
specified); ultrastructural alterations in seminal vesicles, most prominent in infancy
and post-infancy groups (frequency not specified).
Hyper-responsiveness to stimulation with both GnRH and LH (10); blunted
response to naloxone stimulation (10).
Suppressed intratesticular sperm counts, sperm production rate, and serum
testosterone in both Pb treated groups (10—10); sperm parameters and serum
testosterone normalized at the end of the recovery period in the pre-pubertal animals
(27 days at start) (10) but not in the pubertal animals (52 days at start) (5).
Decreased sperm concentration, sperm production rate and suppressed serum
testosterone concentrations after 14 days of exposure; not dose related (NS).
Dose-related suppression of spermatogenesis (decreased sperm count and sperm
production rate) in the exposed rats of the two highest age groups (p < 0.05); dose-
related suppression of serum testosterone in 52-day old rats (p = 0.04) and in 70-day
old rats (p < 0.003).
Blood Lead Concentration
(PbB)
PbB >200 ug/dL
Chronic PbB <40-50 ug/dL
PbB 30 ± 5 ug/dL
<3-43 ug/dL (<4-18 ug/dL after
recovery period)
Bl <3^13 ug/dL(<4-18 ug/dL
after recovery period)
Controls: <8 ug/dL at any time
exposed: 42, 60, 58, 75 ug/dL
after 7, 14, 30, and 60 days,
respectively
0% All <7 ug/dL
42 days 25 ug/dL
0.1% 52 days 35 ug/dL
70 days 37 ug/dL
42 days 36 ug/dL
0.3% 52 days 60 ug/dL
70 days 42 ug/dL
-------
Table AX5-4.2 (cont'd). Effect of Lead on Reproduction and Development in Mammals Effects on Males
X
Citation
Sokol et al.
(1985)T
Sokol et al.
(1994)
Sokol et al.
(2002)
Thoreux-
Manlay et al.
(1995a)
Thoreux-
Manlay et al.
(1995b)
Wadi and
Ahmad (1999)
Wenda-
Rozewicka
et al. (1996)
Yu et al.
(1996)
Species/
Strain/Age
Rat/Wistar,
52 days old
Rat/Sprague-
Dawley,
100 days old
Rat/Sprague-
Dawley, adult
Rat/Sprague-
Dawley, 97 days
old
Rat/Sprague-
Dawley, adult
Mouse/CF-1,
adult
Rat/Wistar,
adult
Rat/Sprague-
Dawley,
neonates
Dose/Route/Form/Duration
0.1 or 0.3% Pb acetate in
drinking water for 30 days
0.3% Pb acetate in drinking
water for 14, 30, or 60 days
Pb acetate in water for 1 wk
0-8 mg Pb acetate/kg i.p. for
5 days/wk, 35 days
8 mg/kg-d Pb for 5 days/wk,
35 days
0.25 and 0.5% Pb acetate in
drinking water for 6 wks
1% aqueous solution of Pb
acetate for 9 mo
Neonatal and lactational
exposure to 0.3% Pb acetate
in drinking water beginning
PND 1 to PND 21
1 ml point
Negative correlations between PbB levels and serum and intratesticular testosterone
values; dose-dependent reduction in intratesticular sperm count; FSH values were
suppressed; no change in LH; decrease in ventral prostatic weight; no difference in
testicular or seminal vesicle weights.
Pb exposed fertilized fewer eggs; increased duration of exposure did not result in more
significant percentage of eggs not fertilized; no ultrastructural changes were noted in
the spermatozoa of animals; no difference in histogram patterns of testicular cells.
Dose-related increase in gonadotropin-releasing hormone (GnRH) mRNA; no effect
on the serum concentrations of hypothalamic gonadotropin-releasing hormone (GnRH)
orLH.
No effects on spermatogenesis; decreased plasma and testicular testosterone by 80%;
decreased plasma LH by 32%, indications for impaired Leydig cell function, no effects
on fertility.
Germ cells and Sertoli cells were not major target of Pb, accessory sex glands were
target; epididymal function was unchanged; plasma and testicular testosterone dropped
about 80%, plasma LH only dropped 32%.
Low dose significantly reduced number of sperm within epididymis; high dose reduced
both the sperm count and percentage of motile sperm and increased the percentage of
abnormal sperm within the epididymis; no significant effect on testis weight, high dose
significantly decreased the epididymis and seminal vesicles weights as well as overall
body weight gain; LH, FSH, and testosterone were not affected.
Electron microscopic studies did not reveal any ultrastructural changes in the
semiferous epithelium or in Sertoli cells; macrophages of testicular interstitial tissue
contained (electron dense) Pb-loaded inclusions, usually located inside phagolisosome-
like vacuoles; x-ray micro-analysis revealed that the inclusions contained Pb.
Neonatal exposure to Pb decreased cold-water swimming endurance (a standard test for
stress endurance) and delayed onset of puberty in males and female offspring, which
was exacerbated by swimming stress.
Blood Lead Concentration
(PbB)
PbB 34 ± 3 ug/dL or
PbB 60 ± 4 ug/dL
PbB -40 ug/dL
PbB 12-28 ug/dL
PbB not reported
PbB 1700 ug/dL
PbB not reported
PbB not reported
PbB 70 ug/dL
*Not including effects on the nervous or immune systems.
t Candidate key study.
36-HSD, 36-hydroxysteriod dehydrogenase; dbcAMP, dibutyryl cyclic adenosine-3',5'-monophosphate; DTT, dithiothreitol; FSH, follicle stimulating hormone; G6PDH, glucose-6-phosphate
dehydrogenase; GD, gestational day; GnRH, gonadotropin releasing hormone; hCG, human chorionic gonadotropin; IGFb insulin-like growth factor 1; i.p., intraperitoneal; LDH, lactate
dehydrogenase; LH, luteinizing hormone; LHRH, luteinizing hormone releasing hormone; LPP, lipid peroxidation potential; NCD, nuclear chromatin decondensation rate; NOS, not otherwise
specified; PbB, blood lead concentration; PND, post-natal day; p.o., per os (oral administration); ROS, reactive oxygen species; SDH, succinic acid dehydrogenase; SOPR, sperm-oocyte penetration
rate; StAR, steroidogenic acute regulatory protein; VC, vitamin C; VE, vitamin E; VMA, vanilmandelic acid
-------
Table AX5-4.3. Effect of Lead on Reproduction and Development in Mammals Effects on Females
X
Citation
Burright et al.
(1989)
Coffigny et al.
(1994)T
Corpas et al.
(2002a)
Cory-Slechta
et al. (2004)T
Dearth et al.
(2002)T
Species/
Strain/Age
Mouse/HET,
neonates
Rat/Sprague-
Dawley, adult
Rat/Wistar,
adult
Rat/Long-Evans,
adult
Rat/Fisher 344,
150-175 g
Dose/Route/
Form/Duration
0.5% Pb acetate solution via
milk, or drinking water
chronic beginning PND 1
Inhalation exposure to
5 mg/m3 Pb oxide daily for
13 days during gestation
(GD 2, 3, 6-10, 13-17, 20)
300 mg/L acetate Pb in
drinking water from mating
until PND 12 or PND 21
Pb acetate in drinking water
beginning 2 mo before
breeding through weaning
12 mg/mL Pb acetate gavage
from 30 days prior breeding
Endpoint
Plasma prolactin levels implied that Pb exposure alone decreased circulating prolactin
in primiparous; low prolactin levels in non-behaviorally tested females suggests that
dietary Pb alone may alter plasma-hormone in these lactating HEX dams; pattern of
plasma prolactin appear to be inconsistent with the observation that Pb exposure
decreases dopamine; prolactin levels of Pb exposed dams were very low.
No effects on the incidence of pregnancy, prenatal death, or malformations when male
and female rats from mothers who had been exposed.
Neither abnormalities in the liver structure nor depositions of Pb, toxicant produced
biochemical alterations; pups exhibited decrease in hemoglobin, iron and alkaline, and
acid phosphatase levels and an increase in Pb content; protein, DNA, and lipid total
amounts were reduced, and hepatic glycogen content was diminished at 12 and 21 PN,
with a higher dose of glucose in blood; decrease in alkaline phosphatase in liver of pups
at day 2 1 PN, but acid phosphatase was unaltered.
Observed potential effects of Pb and stress in female; Pb alone (in male) and Pb plus
stress (in females) permanently elevated corticosterene levels in offspring.
Delay in onset of puberty (p < 0.05); reduced serum levels of IGF1 (p < 0.001), LH
(p < 0.001), and E2 (p < 0.001).
Blood Lead Concentration
(PbB)
PbB -100 ug/dL
PbB 7 1.1 ug/dL (dam)
PbB 83.2 ug/dL (fetal)
PbB 22 ug/dL
PbB 30-40 ug/dL
Maternal PbB: -40 ug/dL
Pups PbB as follows:
Dearth et al.
(2004)
Rat/Sprague-
Dawley and
Fisher-344,
adult
until pups were weaned
21 days after birth; 10-
32 litters per group, control
group, gestation and lactation
exposure, gestation only
exposure, lactation only
exposure
12 mg/mL Pb acetate by
gavage 30 days prior to
breeding through PND 21
(gestation and lactation
exposure)
Pb delayed the timing of puberty in PbB 37.3 ug/dL Pb group and suppressed serum
levels of LH and E2, these effects did not occur in PbB 29.9 ug/dL Pb group, when
doubling dose to 29.9 ug/dL group the PbB levels rose to 62.6 ug/dL, yet no effect was
noted; results indicate that offspring are more sensitive to maternal Pb exposure with
regard to puberty related insults than are 29.9 ug/dL rats.
Gest+lact: -38 ug/dL PND 10
Gest+lact: -15 ug/dL PND 21
Gest+lact: -3 ug/dL PND 30
Gest: -14 ug/dL PND 10
Gest: -3 ug/dL PND 21
Gest: -1 ug/dL PND 30
Lact: -28 ug/dL PND 10
Lact: -15 ug/dL PND 21
Lact: -3 ug/dL PND 30
PbB 29.9 ug/dL (Sprague-
Dawley)
PbB 37.3 ug/dL (Fisher)
-------
Table AX5-4.3 (cont'd). Effect of Lead on Reproduction and Development in Mammals Effects on Females
>
X
Citation
Foster (1992)
Foster et al.
(1992)
Foster et al.
(1996b)
Franks et al.
(1989)
Fuentes et al.
(1996)
Gorbel et al.
(2002)
Species/
Strain/Age
Monkey/
Cynomolgus,
0-10 yrs old
Monkey/
Cynomolgus,
10 yrs old
Monkey/
Cynomolgus,
15-20 yrs old
Monkey/Rhesus,
adult
Mouse/Swiss,
adult
Rat/NOS,
3 mo old
Dose/Route/
Form/Duration
Daily dosing for up to 10 yrs
with gelatin capsules
containing Pb acetate
(1.5 mg/kg); 8 control group
monkeys, 8 lifetime exposure
(birth-10 yrs), 8 childhood
exposure (birth-400 days),
and 8 adolescent exposure
(postnatal day 300-10 yrs of
age)
Daily dosing for up to 10 yrs
with gelatin capsules
containing Pb acetate
(1.5 mg/kg); 8 control group
monkeys, 8 childhood (birth—
400 days), 7 adolescent
(postnatal day 300-10 yrs),
7 lifetime (birth-10 yrs)
Chronic exposure to Pb
acetate 50 to 2000 ug/kg-d
p.o. beginning at birth for
15-20 yrs; 20 control
monkeys, 4 monkeys in
50 ug/kg-d group, 3 monkeys
in 100 ug/kg-d, 2 monkeys in
500 ug/kg-d group, and
3 monkeys in 2000 ug/kg-d
group
Pb acetate in drinking water
(2-8 mg/kg-d) for 33 mo; 7
control and 10 Pb monkeys
14, 28, 56, and 1 12 mg/kg Pb
acetate via i.p; one time
exposure on GD 9
3mg(Pl)or6mg(P2)Pb
acetate in drinking water for
15, 30, 45, 60, or 90 days
Endpoint
Statistically significant reductions in circulating levels of LH (p < 0.042), FSH
(p < 0.041), and E2 (p < 0.0001) during menstrual cycle; progesterone concentrations
were unchanged and menstrual cycle was not significantly affected.
No effect on endometrial response to gonadal steroids as determined by ultrasound.
Reduced corpora luteal production of progesterone (p = 0.04), without alterations in E2,
20alpha-hydroxyprogesterone, or menstrual cyclicity.
Reduced circulating concentration of progesterone (p < 0.05); treatment with Pb did not
prevent ovulation, but produced longer and more variable menstrual cycles and shorter
menstrual flow.
Absolute placental weight at 1 12 mg/kg and relative placental weight at 14, 56, and
112 mg/kg were diminished significantly; most sections of placenta showed vascular
congestion, and increase of intracellular spaces, and deposits of hyaline material of
perivascular predominance; trophoblast hyperplasia was also observed, whereas there
was a reinforcement of the fibrovascular network in the labyrinth
Female rats absolute and relative weights of ovary and uterus were unchanged, vaginal
smears practiced in females revealed the estrus phase; fertility was found to be reduced;
Pb level in blood was poorly correlated with the level of poisoning.
Blood Lead Concentration
(PbB)
PbB <40 ug/dL
PbB <40 ug/dL
PbB 10—15 ug/dL in low group
(50 or 100 ug/kg-d)
PbB 25-30 ug/dL in moderate
group (500 or 2000 ug/kg-d)
PbB68.9±6.54ug/dL
PbB not reported
PbB not reported
-------
Table AX5-4.3 (cont'd). Effect of Lead on Reproduction and Development in Mammals Effects on Females
>
X
Citation
lavicoli et al.
(2004)
Junaid et al.
(1997)
Laughlin et al.
(1987)
Logdberg
et al. (1987)
Logdberg
et al. (1988)
McGivern
etal. (1991)T
Nilsson et al.
(1991)
Piasek and
Kostial(1991)
Pinon-
Lataillade
et al. (1995)
Species/
Strain/Age
Mouse/Swiss,
33-37 days old
Mouse/Swiss,
adult
Monkey/Rhesus,
adult
Monkey/
Squirrel, adult
Monkey/
Squirrel, adult
Rat/Sprague-
Dawley, adult
Mouse/NMRI,
adult
Rat/Wistar,
10 wks old
Mouse/NMRI,
adult
Dose/Route/
Form/Duration
0.02,0.06,0.11,0.20,2.00,
4.00, 20.00, 40.00 ppm in
food Pb acetate concentration
beginning GD 1 to 3 mo after
birth
0, 2, 4, or 8 mg/kg-d Pb
acetate, subchronic exposure,
5 days/wk, 60 days
Pb acetate in drinking water
at 3.6, 5.9, or 8. 1 mg/kg-d for
1-2 yrs; 7 control and 10
experimental monkeys per
group
Pb acetate in drinking water
from 9th week of gestation to
PND 1; per oral exposure
similar to Laughlin et al.
(1987)
Pb acetate maternal dosing
from 5-8.5 wks pregnant to
PND 1
1 1 control monkeys, 3 low-
Pb exposure group (PbB
24 ug/dL), 7 medium Pb
group (PbB 40 ug/dL, 5 high-
Pb group (PbB 56 ug/dL)
0. 1% Pb acetate in drinking
water from GD 14 to
parturition
75 ug/g bw Pb chloride via
i.v.; one time injection on
GD4
7500 ppm Pb acetate in
drinking water for 9 wks
0-0.5% Pb acetate in
drinking water exposed to Pb
during gestation until post-
GD60
Endpoint
Increase in food consumption; however, did low-dose group increase food consumption
because of sweet nature of Pb. Body weight may contribute to delay in onset of puberty
and confound results.
Altered follicular development.
Reductions in cycle frequency (p < 0.01); fewer days of flow (p < 0.01); longer and
more variable cycle intervals (p < 0.025).
Increase in pre- and perinatal mortality during the last two-thirds of pregnancy;
statistically significant reduction in mean birth weight was observed in Pb exposed
monkeys as compared to controls.
Dose-dependent reduction in placental weight (p < 0.0007); various pathological lesions
were seen in the placentas, including hemorrhages, hyalinization of the parenchyma
with destruction of the villi, and massive vacuolization of chorion epithelium.
Female rats showed delay in vaginal opening; 50% exhibited prolonged and irregular
periods of diestrous and lack observable corpora lutea; both sexes showed irregular
release patterns of both FSH and LH.
Electron microscopy showed that the uterine lumen, which was closed in control mice,
was opened in Pb-injected mice; suggested that Pb caused increase in uterine secretion;
study suggested Pb could have a direct effect on the function of the uterine epithelium
and that Pb was secreted into the uterine lumen and affect the blastocysts.
Decrease in litter size, pup survival, and birth weight; food consumption, body weight,
and fertility were not altered in 20 wk exposure period.
Exhibited reduced fertility as evidenced by smaller litters and fewer implantation sites.
Blood Lead Concentration
(PbB)
PbB 0.69, 1.32, 1.58, 1.94, 3.46,
3.80, 8.35, 13.20 ug/dL
PbB 22.3-56.5 ug/dL
PbB 44-89 ug/dL
51.2 ug/dL (low dose)
80.7 ug/dL (mid dose)
88.4 ug/dL (high dose)
Mean maternal PbB 54 ug/dL
(39-82 ug/dL)
PbB 37 ug/dL (22-82 ug/dL)
24 (22-26) ug/dL (low dose)
40 (35-46) ug/dL (mid dose)
56 (43-82) ug/dL (high dose)
PbB 73 ug/dL
PbB not reported
Maternal PbB >300 ug/dL
Offspring PbB >220 ug/dL
PbB 70 ug/dL
-------
Table AX5-4.3 (cont'd). Effect of Lead on Reproduction and Development in Mammals Effects on Females
Citation
Species/
Strain/Age
Dose/Route/
Form/Duration
Endpoint
Blood Lead Concentration
(PbB)
>
X
200 ug/dL.
Pups continuously exposed to Pb
225 to 325 ug/dL
Mean PbB in offspring at 0.05%
(w/v) 49 ± 6 ug/dL
Mean PbB in offspring at 0.15%
(w/v) 126 ± 16 ug/dL
Mean PbB in offspring at 0.45%
(w/v) 263 ± 28 ug/dL
PbB in dams 181 ± 14 ug/dL
PbB in pups ranged from 197 ±
82 to 263 ±38 ug/dL, increasing
with age of pups
PbB not reported
PbB of dams 39 ±3.5 SEM
Ug/dL and offspring PbB 2.9 ±
0.28 SEM ug/dL
-------
Table AX5-4.3 (cont'd). Effect of Lead on Reproduction and Development in Mammals Effects on Females
>
X
Citation
Taupeau et al.
(2001)
Tchernitchin
et al. (1998a)
Tchernitchin
et al. (1998b)
Wide (1985)
Wide and
D'Argy (1986)
Wiebe and
Barr(1988)
Wiebe et al.
(1988)
Yu et al.
(1996)
Species/
Strain/Age
Mouse/C57blxC
BA, 8 wks old
Rat/Sprague-
Dawley, 14 days
old
Rat/Sprague-
Dawley, 20 or
21 days old
Mouse/NMRI,
10 wks old
Mouse/NMRI,
adult
Rat/Sprague-
Dawley, adult
Rat/Sprague-
Dawley, adult
Rat/Sprague-
Dawley, adult
Dose/Route/
Form/Duration
10 mg/kg-d Pb nitrate via i.v.
for 15 days
172 ug/g bw Pb from day 14
every 2nd day until day 20
(75 mg/g bw) Pb via i.v. one
time exposure at 1 or
24 before hormone
stimulation
20 ug/dL/g bw Pb chloride
via i.v. single exposure on
days 8, 12, or 16 after mating
20 ug/g bw by i.v. single
injection on GD 8
20 or 200 ppm Pb chloride in
drinking water; 3 exposure
durations; prior to mating
through weaning, GD 7 to
weaning, PND 21 to PND 35
20 or 200 ppm Pb chloride in
drinking water; 4 exposure
durations; prior to mating
through weaning, GD 7 to
weaning, PND 21 to PND 35,
prior to mating only
Neonatal and lactational
exposure to 0.3% Pb acetate
in drinking water (PND 30)
Endpoint
Low Pb concentration in the ovary caused dysfunction of folliculogenesis, with fewer
primordial follicles and an increase in atretic antral follicles.
Pb inhibits estrogen- induced uterine eosinophilia at 6 and 24 hr after treatment; Pb also
inhibits estrogen-induced edema in deep and superficial endometrial stoma at 24 hr but
not 6 hr after treatment; myometrial hypertrophy is inhibited under the effect of exposure
at 24 hr of treatment.
Enhanced some parameters of estrogen stimulation and inhibited other estrogenic
responses; interaction with responses to estrogen was different depending on whether Pb
pretreatment was 1 or 24 hr before hormone stimulation; estrogenic responses mostly
affected were uterine eosinophilia, endometrial edema, uterine liminal epithelial,
hypertrophy, and mitosis in various, but not all, uterine cell types, in some cell types,
estrogen-induced mitotic response developed earlier under the effect of Pb exposure.
Litter size and fetal survival varied significantly; small litters and increased numbers of
fetal deaths were observed in mice exposed to Pb on day 8 of intrauterine life; live fetuses
were normal with respect to weight and morphological appearance; ovarian follicle
counts revealed a significantly smaller number of primordial follicles in the latter group,
it suggested that the exposure to Pb at a time of early organogenesis caused the observed
fertility decrease by interfering with the development of the female germ cells.
Primordial germ cells showed a normal body distribution but were significantly fewer at
all four stages compared with those of control embryos of corresponding age; Pb had
interfered with the production or activity of alkaline phosphatase.
Treatment with Pb prior to mating resulted in significant increase in E2-receptor affinity
in 21-day old offspring without a change in E2 receptor number; treatment from day 7 of
pregnancy until weaning of the pups resulted in —35% decrease in E2 receptors per mg
uterine protein when these offspring reached 150 days of age; Pb treatment from 21-35
days old or until 150 days resulted in a significant decrease in uterine E2 receptor number
at 35 and 150 day, respectively.
Exposure to Pb did not affect tissue weights but did cause a significant decrease in
gonadotropin-receptor binding in the pre-pubertal, pubertal, and adult females;
conversion of progesterone to androstenedione and dihydrotestosterone was significantly
decreased in 21-day old rats and in 150-day old females; significantly increased
conversion to the 5-alpha-reduced steroids, normally high during puberty.
Neonatal exposure to Pb decreased cold-water swimming endurance (a standard test for
stress endurance); delayed onset of puberty in males and female offspring, which was
exacerbated by swimming stress.
Blood Lead Concentration
(PbB)
PbB not reported
PbB 47 ug/dL
PbB not reported
PbB not reported
PbB not reported
PbB likely 4.0 ± 1. 4 to 6.6 ±
2.3 ug/dL (similar design as
Wiebe et al. (1988)
PbB range 4.0 ± 1.4 to 6.6 ±
2.3 ug/dL
PbB 70 ug/dL
*Not including effects on the nervous or immune systems.
t Candidate key study.
E2, estradiol; FSH, follicle stimulating hormone; GD, gestational day; GnRH, gonadotropin releasing hormone; HET, Binghamton Heterogeneous Stock; IGFi, insulin-like growth factor 1;
i.p., intraperitoneal; LH, luteinizing hormone; NOS, not otherwise specified; PbB, blood lead concentration; PND, post-natal day; p.o., per os (oral administration); SRIF, somatostatin; StAR,
steroidogenic acute regulatory protein.
-------
ANNEX TABLES AX5-5
AX5-60
-------
Table AX5-5.1. In Vivo and In Vitro Studies of the Effects of Lead Exposure on Production and Metabolism of Reactive
Oxygen Species, Nitric Oxide, and Soluble Guanylate Cyclease
X
Pb Exposure Measured Parameters
Reference
Khalil-
Manesh et al.
(1994)
Gonick et al.
(1997)
Ding et al.
(1998)
Species/
Tissue Age/Weight
Male SD 200 g
rats
Male SD 2 mo
rats 200 g
Male SD 2 mo
rats
n Dosage
N/A Pb-acetate,
100 ppm in
water
6 Pb-acetate,
100 ppm in
water
N/A Pb-acetate,
100 ppm in
water
Duration Pb Level CVS Other
6 mo 7±3.6ug/d BP, tail art. ET-3, cGMP
ring response
toNE
3 mo 12.4 ± 1.8 ug/dL BP cGMP, NO2 +
NO3, ET-1,
ET-3, MDA,
eNOS, iNOS
3 mo 3.2 ± 0.2 ug/dL BP Urine NO2 +
NO3> plasma
MDA
Interventions Results
DMSA Rx Pb caused HTN, |ET3,
|U cGMP (NS) (no
effect on NE reactivity).
DMSA Rx lowered BP
and Vase response to NE
and raised cGMP
— HTN, |MDA, feNOS,
fiNOS (protein and
activity in kidney)
DMSA (0. 5% H2O) Pb caused HTN, |urine
x 2 wks, i.v. NO2+NO3, fplasma
infusions of L. MDA. DMSA lowered
Arg., SOD and SNP BP, blood Pb and MDA
+ raised urine NO2 +
NO3 L-Arg lowered BP
and MDA, raised
N02+N03, SNP lowered
BP
Vaziri (1997) Male SD
rats
190 g
12
Pb-acetate,
100 ppm in
water
3 mo
17±9ug/dL
BP Plasma MDA Antioxidant Rx
urine NO2 + (Lazaroid)
NO3
Pb caused HTN, fMDA,
jurine NO2+NO3 in
untreated animals.
Antioxidant Rx improved
HTN, urine N02+N03
and lowered MDA
without changes in blood
Pb level
Dursun
(2005)
Male SD
rats
24
Pb acetate
8 mg/kg IP
2 wks
BP, RBF
Ur Na, Ur
N02 + N03,
24 hr UrNa
(Na+ intake
Not given)
|BP, |RBF, |UrN02 +
NO3, unchanged UrNa+
-------
Table AX5-5.1 (cont'd). In Vivo and In Vitro Studies of the Effects of Lead Exposure on Production and Metabolism of
Reactive Oxygen Species, Nitric Oxide, and Soluble Guanylate Cyclease
X
4 per 0 and 1 ppm 24 hrs w/Pb 1 ppm medium
Ding (2001) coronary experiment Pb acetate or Na acetate
endothelial followed
cells by 24 hrs
w/tempol or
vehicle
Measured Parameters
CVS Other
BP Aorta and
kidney eNOS
protein
abundance, Ur
N02 + N0
BP Aorta, heart,
kidney and brain
NOS isoforms,
urine NO2 +
N03
N/A eNOS
expression
Interventions
Subgroups
treated with high-
dose vitamin E
Subgroups
studied after 2
wks of Rx
w/tempol and
those studied 2
wks after
cessation of
tempol Rx
Co-treatment
w/O2' scavenger,
tempol
Results
Pb exposure resulted in a
time-dependent rise in
BP, aorta and kidney
eNOS and iNOS. This
was associated w/a
paradoxical fall in NO
availability (Ur NO2 ±
NO3). Antioxidant Rx
attenuated upregulation
of iNOS and eNOS and
raised NO availability.
Pb exposure resulted in
rises in BP, eNOS, iNOS
and nNOS in the tested
tissues + jurine NOX.
Tempol administration
attenuated HTN, reduced
NOS expressions and
increased urine NOX.
The effects of tempol
disappeared within 2 wks
of its discontinuation.
Pb exposure for 48 hr
upregulated eNOS
expression. Co-treatment
w/ tempol resulted in
dose-dependent reversal
of Pb-induced
upregulation of eNOS
but had no effect on
control cells.
-------
Table AX5-5.1 (cont'd). In Vivo and In Vitro Studies of the Effects of Lead Exposure on Production and Metabolism of
Reactive Oxygen Species, Nitric Oxide, and Soluble Guanylate Cyclease
X
Pb Exposure
Species/
Reference Tissue Age/Weight n Dosage Duration Pb Level
Vaziri et al. Male SD rats 200 g 6 per group lOOppmin 3 mo 8.3— 10.8 ug/g
(1999a) water kidney tissue
Vaziri et al. Male SD rats 200 g 6 per group lOOppmin 3 mo N/A
(2003) water
Nietal. Cultured N/A >4per 0,1 and 10 Short 0,1, 10 ppm
(2004) human experiment ppm Pb exposure
coronary acetate (5-30 min)
endothelial and and long
VSM cells. exposure
(60 hr)
Measured Parameters
CVS Other Interventions
BP Urine NO2 + Antioxidant Rx
NO3, tissue and (Vit E)
plasma
nitrotyrosine
(marker of
NO-ROS
interaction).
BP Urine NO2 + Tempol (O2'
NO3, kidney, scavenger
heart, brain infusion)
SOD, catalase,
GPX, NAD(P)H
oxidase
abundance
N/A O2' and H2O2 None
productions
SOD, catalase,
GPX and
NAD(P)H
oxidase
(gp91phox)
Results
Pb exposure raised BP,
reduced Ur NO2 + NO3
and increased
nitrotyrosine abundance
in plasma, heart, kidney,
brain and liver. Anti ox
Rx ameliorated HTN,
lowered nitrotyrosine and
raised Ur NO2 + NO3.
Pb caused HTN,
|NAD(P)H oxidase
(gp91phox), fSOD, un-
changed catalase and
GPX, |UrNO2 + NO3.
Tempol resulted in |BP
+ furine NO2 + NO3 in
Pb-exposed but not
control rats.
Short-term incubation
with Pb at 1 and 10 ppm
raised O2'and H2O2
productions by both
endothelial and VSM
cells, long-term
incubation resulted in
further rise in H2O2
generation and
normalization of
detectable O2y°. This was
associated with increases
in NAD(P)H oxidase and
SOD and reduced or
unchanged catalase and
GPX.
-------
Table AX5-5.1 (cont'd). In Vivo and In Vitro Studies of the Effects of Lead Exposure on Production and Metabolism of
Reactive Oxygen Species, Nitric Oxide, and Soluble Guanylate Cyclease
X
Species/
Reference Tissue
Ding et al. Male SD rats
(2001)
Ding et al. Cultured rat
(2000) aorta
endothelial
cells
Attri (2003) Male Wistar
Kyoto rats
Malvezzi Male Wistar
(2001) rats
Pb Exposure
Age/Weight n Dosage Duration Pb Level
2 mo N/A 100 ppm 3 mo BloodPbl2.4±
200 g 1.8ng/dLvs. 1
mg/dL in
controls
N/A >4 0-1 ppm 1,2, 24, 84 hr 0-1 ppm culture
experiment media
150-200 g 10 per Pb acetate, 1-3 mo Blood Pb
group 100 ppm in 1.5 mg/dL at
water ± 1 mo
Vit C 20
mg/d/rat 2.4 mg/dL at
2 mo
4. 1 mg/dL at
3 mo
5—6 wks 4—10 per Pb acetate 100 days Blood, bone,
(170 g) group 750 ppm in kidney, aorta,
water liver
Measured Parameters
CVS Other Interventions
BP Response to i.v. infusion of
DMTU DMTU
administration,
tissue
nitrotyrosine,
hydro xyl radical
N/A Hydroxyl radical None
production using
the following
reaction (Na
Salicylate + OH
— > 2,3dihydroxy
benzoic acid),
MDA
BP Total antioxidant Response to
capacity, ferric- vitamin C.
reducing
antioxidant
power, NO
metabolites,
MDA,
8-hydroxy guano
sine
BP — Response to L.
arg, DMSA, L.
arg .+ DMSA
(given together
w/Pb in last
30 days
Results
Pb caused HTN, fplasma
nitrotyrosine,
tplasma.OH
concentration all reversed
with .OH-scavenger,
DMTU infusion
Pb exposure resulted in
cone-dependent rise in
MDA and OH
production by cultured
endothelial cells.
Pb caused |BP, |MDA,
|DNA damage/
oxidation, |NOX,
jantioxidant and ferric-
reducing antioxidant.
Concomitant Rx with Vit-
C ameliorated all
abnormalities.
|BP w/Pb, partial |BP
w/L. Arg or DMSA,
greater reduction w/both,
blood and aorta PB
remained | in all but
DMSA + L. Arg group.
Significant Pb
mobilization shown in
other organs.
-------
Table AX5-5.1 (cont'd). In Vivo and In Vitro Studies of the Effects of Lead Exposure on Production and Metabolism of
Reactive Oxygen Species, Nitric Oxide, and Soluble Guanylate Cyclease
X
Reference
Khalil-
Manesh et al.
(1993b)
Marques et al.
(2001)
Farmand et al.
(2005)
Courtois et al.
(2003)
Species/
Tissue Age/Weight
Male SD 8 wks
rats
Male 3 mo
Wistar rats
Male SD 200 g
rats
Rat N/A
thoracic
Pb Exposure
n Dosage Duration
N/A Pb acetate 100 or 1-12 mo
5000 ppm in
water
20 Pb acetate 5 ppm 30 days
± Vit C (3
mmol/L) in
water
8 Pb acetate 100 3 mo
ppm in water
6/ 0-1 ppm 24 hr
experiment
Measured
Pb Level CVS
29 ±4 ug/dL BP, vascular
contractility to
NE in vitro
N/A BP, arch-, SNP-
vasorelaxation
response in aorta
rings
N/A BP
0-1 ppm cGMP
production
Parameters
Other Interventions
cGMP, ET-3, ANP —
sGC protein mRNA CoTx with Vit C
and activity.
cGMP production,
eNOS protein
Aorta sGC, SOD, —
catalase,
glutathione
peroxidase
sGC expression, Vit C, COX-2
superoxide inhibitor
Results
Pb caused HTN,
jserum and urine
cGMP, tserum ET-3
without changing ANP
or response to NE
Pb caused HTN,
^relaxation to Ach and
SNP, feNOS, |sGC
protein mRNA and
activity. These
abnormalities were
prevented by
antioxidant Rx.
|sGC, fCuZn SOD
activity, unchanged
catalase and GPX
activities.
Pb caused |sGC,
icGMP, T02- TCOX-2.
aorta
production, COX-2
All abnormalities
improved by Vit C.
COX-2 inhibitor
improved sGC
expression but not O2
production.
-------
Table AX5-5.2. Studies of the Effects of Lead Exposure on PKC Activity, NFkB Activation, and Apoptosis
X
ON
ON
Species/ Age/
Reference Tissue Weight n
Watts et al. Isolated rabbit N/A 5—6 sets per
(1995) mesenteric experiment
artery
Rodriguez- Male SD rats 200 g 8 Pb group
Iturbe et al. 9 controls
(2005)
Pb Exposure Measured Parameters
Dosage Duration Pb Level CVS Other Interventions Results
Pb acetate Immediate 5 10-10 3M Vascular Preincubation Pb acetate induced
10~10-10~3M (contraction) medium contraction w/PKC contraction which was
activators, PKC potentiated by PKC
inhibitor or activators and
verapamil for attenuated by PKC
30—60 min + inhibitor (role of
endothelium PKC). CCB
denudation attenuated Pb-induced
contraction
(contribution of Ca2+
entry). Removal of
endothelium did not
affect Pb-induced
vasoconstriction.
Pb acetate 3 mo N/A NFkB activation, Pb-exposed animals
100 ppm in apoptosis, Ang II showed
drinking positive cells, tubuloniterstitial
water macrophage/T cell accumulation of
infiltration and activated T-cells,
nitrotyrosine staining macrophages and Ang
in renal tissue II positive cells, NFkB
activation increased
apoptosis and
nitrotyrosine staining
in the kidney.
-------
Table AX5-5.3. Studies of the Effects of Lead Exposure on Blood Pressure and Adrenergic System
X
Pb Exposure Measured Parameters
Species/ Age/
Reference Tissue Weight
Chang et al. Wistar rats 190-200 g
(1997)
Tsao et al. Wistar rats 190—200 g
(2000)
Carmignani Male SD rats 3 mo
et al. (2000)
n Dosage
20 Pb acetate
0.5% in
drinking
water
70 Pb acetate
0-2% in
drinking
water
24 60 ppm
Duration Pb Level CVS
2 mo Blood 29. 1 ± BP
1.9 ug/dL
aorta; 1.9±
0.2 ug/g
2 mo Blood, heart, BP, p agonist-
aorta, kidney stimulated
cAMP
production
(10 uM
isoproterenol
in vitro)
10 mo Blood 22. 8 ± BP, HR,
1.2 ug/dL cardiac
contractility
(dP/dt), blood
flow
Other
Plasma
catecholamines +
aorta; p receptor
binding assay and
cAMP generation
pi NEpi, cAMP p
receptor densities
Plasma NE, Epi,
dopamine, monoamine
oxidase (MAO)
activity, histology
Reference Species/Tissue
— Pb exposure caused
HTN, elevated plasma
NE (unchanged
plasma Epi).
I isoproterenol-
stimulated plasma
cAMP, 4 p receptor
density in aorta.
— Pb exposure raised BP
and pi NE + lowered
aorta and heart p
receptor density, basal
and stimulated cAMP
productions +
increased kidney p
receptor density and
basal and stimulated
cAMP productions.
— Pb exposure raised BP
and dp/dt, lowered
carotid blood flow, (no
change in HR) raised
plasma NE and Epi
and MAO (all tissues)
lowered plasma NOx
+ 4 aorta media
thickness,
| lymphocyte
infiltration in
periaortic fat,
nonspecific change in
kidney (congestion,
edema, rare prox.
tubular cell necrosis).
-------
Table AX5-5.3 (cont'd). Studies of the Effects of Lead Exposure on Blood Pressure and Adrenergic System
X
OO
Species/ Age/
Reference Tissue Weight
Lai et al. Male SD rats 300 g
(2002)
Chang et al. Male Wistar 10 wks
(2005) rats
Pb Exposure
n Dosage Duration Pb Level
Acute In vivo: — —
response Intrathecal
injection of
PbC12, 10-
100 nM.
In vitro:
Thoracic cord
slices exposed
to 5-50 uM
PbC12
70 2% Pb acetate 2 mo, Blood:
(drinking observed for 85 ug/dL
water) 7 mo after
cessation Aorta:
8 n/g/g
Heart:
1 ug/g
Kidney:
60 ug/g
Measured Parameters
CVS Other Interventions Results
BP, HR, (In vivo) Electophysiologi — In vivo: IT injection
w/without c measures (In of PbC12 raised BP
ganglionic blockade vitro) and HR. This was
(Hexomethonium) before/after reversed by ganglionic
saline washout blockade. In vitro: Pb
raised excitatory and
lowered inhibitory
postsynaptic potentials
which were reversed
by removal of Pb
(saline washout)
BP Plasma NE, p Cessation of Pb Pb exposure raised
recaptor density exposure BP, plasma NE, and
(aorta, heart, renal tissue p receptor
kidney) and lowered
aorta/heart p receptor
density. Plasma and
tissue Pb fell to near-
control values within 7
mo. after Pb cessation.
This was associated
with significant
reductions (not
normalization) of BP,
plasma NE and partial
correction of tissue p
receptor densities
(Bone Pb was not
measured).
-------
Table AX5-5.4. Studies of the Effects of Lead Exposure on Renin-angiotensin System, Kallikrein-Kinin System,
Prostaglandins, Endothelin, and Atrial Natriuretic Peptide (ANP)
X
-------
Table AX5-5.5. Studies of Effect of Lead on Vascular Contractility
X
Pb Exposure
Species/ Age/
Reference Tissue Weight n Dosage Duration Pb Level
Shelkovnikov Rat aorta rings Pb acetate Short —
andGonick l(T8to 10~4 incubations
(2001)
Purdyetal. Male SD rats 8 wks Pb acetate 100 3 mo —
(1997) ppm in water
Oishi et al. Male Wistar Pb acetate 1-3 mo
(1996) rats
Valencia et al. Wistar rat 7 wks 6 sets/ Pb acetate Rapid —
(2001) thoracic aorta experiment 0.1— 3.1mM response
rings in vitro
Measured Parameters
CVS Other
Vasoconstriction/
vasodilation
BP Aorta ring
response to NE,
phenylephrine,
acetylcholine, and
nitroprusside
Mesenteric art
and aorta
response to
acetylcholine in
presence or
absence of NOS
inhibitor (L-
NAME)
In vitro
contractile
response
Interventions Results
Pb acetated did not cause
Vasoconstriction and did
not modify the response
to NE, isoproterenol,
phorbol ester or
acetylcholine but raised
contractile response to
submaximal Ca2+
concentration
Pb exposure raised BP.
Aorta ring
vasoconstrictive response
to NE and phenylephrine
and vasodilatory
response to acetylcholine
and nitroprusside were
unchanged.
Vasorelaxation response
to acetylcholine in
presence of L-NAME
was significantly reduced
in mesenteric art, but not
aorta of Pb-exposed
animals (Inhibition of
hyperpolarizing factor)
Pb induced a
concentration-dependent
Vasoconstriction in intact
and endothelial-denuded
rings in presence or
absence of a- 1 blacker,
PKC inhibitor, L. type
Ca + channel blocker or
intra- and extracellular
Ca2+ depletion.
However, the response
was abrogated by
lanthanum (a general Ca
channel blocker)
-------
Table AX5-5.6. Effects of Lead on Cultured Endothelial Cell Proliferation, Angiogenesis, and
Production of Heparan Sulfate Proteoglycans and tPA
X
Reference
Kaji et al.
(1995a)
Kaji et al.
(1995b)
Fujiwara et al.
(1998)
Kishimoto
etal. (1995)
Ueda D. et al.
(1997)
Pb Exposure
Species/ Age/
Tissue Weight n Dosage Duration Pb Level
Bovine aorta — 4 sets per Pb nitrate 24 hrs
endothelial experiment 5—50 uM
cells
— 4-5 sets per Pb nitrate 24 hrs
experiment 0.5—5 uM
Bovine aorta — 6 set per Pb nitrate 48 hrs
endothelial experiment 5 and 10 uM
cells
Human- — 3 sets per Pb acetate 24 hrs
umbilical vein experiment 1—100 fM.
endothelia
cells
Human — 3 sets per Pb acetate 24 hrs
umbilical vein experiment 1—100 uM
endothelial
cells
Measured Parameters
CVS Other
— Endothelial
damage
— 3H-thymidine
incorporation, cell
count,
morphology,
LDH release
— Appearance of
cells in denuded
areas of
monolayer, DNA
synth
— Formation of
tube-like
structures (angio-
genesis assay, on
Matrigel (BM)
— Tube formation
on Matrigel
matrix
Interventions Results
Co-incubation Addition of Pb alone
with cadmium resulted in mild
deendothelialization of
the monolayers and
markedly increased
cadmium-associated
endothelial damage.
Stimulation Incubation w/Pb resulted
w/pFGF and in a concentration-
aFGF dependent reduction of
DNA synthesis and cell
count, caused some shape
change (polygonal
— >spindle) and reduced
pFGF- and aFGF-
mediated proliferation.
Stimulation Pb inhibited appearance
w/Zn of endothelial cells in the
denuded section of
monolayer and attenuated
the healing response to
Zinc.
— Pb inhibited tube
formation concentration-
dependently and tube
lengthening time
dependently.
PKC activator Pb inhibited tube
and inhibitor formation concentration-
dependently and tube
lengthening time
dependently. These
effects were independent
of PKC.
-------
Table AX5-5.6 (cont'd). Effects of Lead on Cultured Endothelial Cell Proliferation, Angiogenesis, and
Production of Heparan Sulfate Proteoglycans and tPA
X
to
Reference
Fujiwara and
Kaji
(1999)
Kaji et al.
(1991)
Kaji et al.
(1997)
Pb Exposure
Species/ Age/
Tissue Weight n Dosage Duration Pb Level
Bovine aorta — 4 sets per Pb nitrate 12—48 hrs
endothelial experiment 0.5, 1, 2 uM
cells
Bovine aorta — 4-5 sets per Pb nitrate 24-48 hrs
endothelial experiment 0, 1-20 uM
cells
Bovine aorta — N/A Pb chloride 24 hrs N/A
endothelial 10 M
cells
(confluent)
Measured Parameters
CVS Other
pFGF production/
distribution
Heparan sulfate
production (sulfate
incorporation)
DNA synthesis (cell
proliferation)
pFGF binding assay
Glycosaminoglycan
(GAG) synthesis
(sulfate incorporation)
Synthesis of heparan
sulfate proteoglycans
(HSPGs) and their core
proteins
Interventions Results
Heparin, Anti- Pb and anti-pFGF alone
pFGF antibody or together equally
reduced DNA synthesis.
PB did not change
endogenous pFGF
production but reduced
its HSPG-bound
component. This was
due to diminished
heparan sulfate synthesis
as opposed to
interference with pFGF
binding property.
At 10 MM, Pb
significantly reduced
production of total
GAGs. Heparan sulfate
was reduced more
severely than other
GAGs. Cell surface
GAG was reduced more
severely than found in
the medium.
In confluent cells, Pb
suppressed incorporation
of precursors into HSPG
in the cell layer to a
greater extent than
chondroitin/dermatan
sulfate proteoglycans. Pb
suppressed low-
molecular weight HSPGs
more than the high-
molecular weight
subclass. The core
proteins were slightly
increased by Pb
exposure.
-------
Table AX5-5.6 (cont'd). Effects of Lead on Cultured Endothelial Cell Proliferation, Angiogenesis, and
Production of Heparan Sulfate Proteoglycans and tPA
X
Reference
Fujiwara and
Kaji
(1999)
Kaji et al.
(1992)
Pb Exposure
Species/ Age/
Tissue Weight n Dosage Duration Pb Level
Bovine aorta — 4 sets per Pb nitrate 48 hrs
endothelial experiment 0.1 uM
cells (growing
10% BCS)
Human — 5 sets per 0.01—1 uM
umbilical vein experiment
endothelial
cells
(confluent)
Measured Parameters
CVS Other
Sulfate and
glucosamine
incorporation in GAGs,
quantification of high
and low MW-HSPG,
identification of
perlecan core protein
t-PA release, DNA
synth, protein synth
(leucine incorporation)
Interventions Results
In growing cells, Pb
depressed high-MW
HSPGs production but
had little effect on low-
MW HSPGx (-50 KD).
The core protein of
perlecan (400 KD) was
significantly reduced by
Pb exposure.
Thrombin and Pb exposure reduced
ET- 1 basal and thrombin-
stimulations stimulation t-PA release
and worsened ET- 1
induced inhibition of t-
PA release.
-------
Table AX5-5.7. Studies of the Effect of Lead on Cultured Vascular Smooth Muscle Cells
X
Reference
Fugiwara
etal. (1995)
Carsia et al.
(1995)
Yamamoto
etal. (1997)
Pb Exposure
Species/ Age/
Tissue Weight n Dosage Duration Pb Level
Bovine aorta 4 sets per Pb nitrate 24 hrs
vascular experiment 0.5—10 uM
smooth
muscle cell
Rat aorta > 3 sets per Pb citrate 100 Time to
VSMC cells experiment and 500 ug/L confluence
(80-90% (-90% for
confluent) control
experiments)
Human aorta 5 sets per Pb chloride 24 hrs
VSMC and experiment 0.5-10 uM
fetal lung
fibroblasts
(confluent)
Measured Parameters
CVS Other
— DNA synthesis
Cell density (cell
#/Cm2), cell
morphology,
membrane lipid
analysis, receptor
densities (Ang-II,
a, P, ANP
t-PAandPAI-1
release
Reference Species/Tissue
Coincubation Pb caused a
w/pFGF, concentration-dependent
aFGF. pDGF increase in DNA
synthesis. Co-incubation
w/pFGF and Pb resulted
in an additive stimulation
ofVSMCDNAsynth.
However, Pb inhibited
PDGF and aFGF-
induced DNA synthesis.
At low concentration, Pb
caused VSMC
hyperplasia, phenotypic
transformation from
spindle-to-cobblestone
(neointima-like) shape,
reduced Ang II receptor
density without changing
a, P, ANP receptors,
increased arachidonic
acid content of cell
membrane.
At 2 uM or higher
concentrations, Pb
resulted in a
concentration-dependent
decline in t-PA release in
both cell types. Pb
increased P AI- 1 release
in fibroblasts but lowered
PAI-linVSMC.
-------
ANNEX TABLES AX5-6
AX5-75
-------
Table AX5-6.1. Genotoxic/Carcinogenic Effects of Lead—Laboratory Animal Studies
Compound
Dose and Duration
Cell Type
Co-exposure
Effects
Reference
Pb acetate
X
Pb acetate
0.5, 5, or 25 ppm given in drinking
water-duration not given.
Number of animals per group was
not given.
0^000 ppm given in drinking
water for 104 wks.
Female C3HSI mice
infected with MMTV
(Murine mammary
tumor virus)-age not
given
Selenium, 0.15-
1 ppm (duration not
given) in diet ( Se
prevents spontaneous
tumors in these mice)
Wild type (WT) and None
metallothionine null (MT
null) mice
Pb acetate exposed mice exhibited greater mortality unrelated to Schrauzer (1987)
the tumor formation.
25 ppm suppressed tumor formation, but increased the
aggressiveness of the tumors.
5 ppm increased tumor formation, but had no effect on growth
rates.
0.5 ppm with low selenium exhibited 80% tumor formation and
reduced weight gains that recovered.
0.5 ppm with high selenium exhibited normal weight gain, but
tumor incidence still reached 80%.
Control data described as "significantly lower" but not given.
Methods poorly described and data not shown.
Renal proliferative lesions were much more common and severe Waalkes et al.
in MT null mice than WT mice. MT null mice could not form
renal inclusion bodies even with prolonged Pb exposure and this
could have contributed to increase in the carcinogenic potential
ofPb.
(2004)
Pb acetate 50, 250, or 1000 ppm given in
drinking water for 15 wks.
Number of mice per group in initial
exposures not given.
Number of mice at analysis ranged
from 19-25.
Female albino Swiss
Mice-3 wks old
Urethane 1.5 mg/g
given i.p.
No signs of Pb poisoning. No Pb effects on growth or weight
gain.
Urethane added to induce lung tumors.
Pb did not affect urethane metabolism.
Pb did not affect number of tumors or affect tumor size.
Pb alone was not evaluated.
Pb levels did increase in tissues.
Blakley
(1987)
-------
Table AX5-6.1 (cont'd). Genotoxic/Carcinogenic Effects of Lead—Laboratory Animal Studies
Compound
Dose and Duration
Cell Type
Co-exposure
Effects
Reference
Pb acetate 50 or 1000 ppm 50 or 1000 ppm
given in drinking water for
280 days.
Number of mice pre group in initial
exposures not given.
Number of mice at end were 50 per
dose.
Pb acetate 60 mg/kg injected s.c. weekly for
5 wks followed by observation for
80 wks. 13 treated and 14 control
rats.
X
Female albino Swiss
Mice-8 wks old
Fisher F344/NSle rats-
3 wks old
None Mice have high rate of spontaneous leukemia from endemic viral Blakley
infection. (1987)
No signs of Pb poisoning. No Pb effects on growth or weight
gain.
Pb did increase leukemia-related mortality possibly due to
immunosuppression.
Pb levels did increase in tissues.
Data indicate that Pb may be immunosuppressive, though the
exact mechanism is not understood.
None Pb induced tumors at the site of injection in 42% of rats Teraki and
though data was not shown. Uchiumi (1990)
Control data not indicated or shown.
Pb accumulated in tumor tissue, tooth, and bone. This data
was shown.
Pb acetate 1 or 100 ug/L given in the drinking Male Wistar Rats—
water for 31 wks weanlings
8 animals per group
0.2—4 % calcium
carbonate given in the
diet for 31 wks.
No differences in drinking water or food consumption.
High Pb and high calcium reduced growth.
No deaths in low calcium groups.
10/24 rats from high calcium diet died (4 from controls and 3
each from Pb groups). All 10 had kidney or bladder stones.
0/8 rats in low calcium no Pb had kidney pathology
2/8 rats in low calcium low Pb had nephrocalcinosis.
7/8 rats in low calcium high Pb had nephrocalcinosis.
3/4 rats in high calcium no Pb had nephrocalcinosis.
1/5 rats in high calcium low Pb had a renal pelvic carcinoma.
3/5 rats had nephrocalcinosis.
3/5 rats in high calcium high Pb had transitional cell
hyperplasia. 2/5 rats had invasive renal pelvic carcinoma.
Pb tissue levels were same regardless of dietary calcium
levels.
Bogden et al.
(1991)
-------
Table AX5-6.2. Genotoxic/Carcinogenic Effects of Lead—Human Cell Cultures
X
oo
Compound
Pb chromate
Pb chromate
Dose and Duration
Anchorage Independence
(0.1-1 uMfor48h)
Anchorage Independence
(0.1-1 uMfor48h)
Cell Type
Human Foreskin
Fibroblasts
InH-MEM+15%FCS
Human Foreskin
Fibroblasts
Co-exposure
None
None
Effects
Pb chromate-induced concentration-dependent increase in
anchorage independence.
Pb chromate-induced concentration-dependent increase in
anchorage independence.
Reference
Biedermann and
Landolph (1987)
Biedermann and
Landolph (1990)
Pb chromate Morphological Transformation
(2 ug/mL for 24 h, performed
3 times immediately after
passage)
Anchorage Independence (0.2—
2 ug/mL or cells isolated during
morphological transformation)
Neoplastic Transformation (cells
isolated during morphological
transformation)
Pb acetate Anchorage Independence
(500-2000 uM for 24 h)
InH-MEM+15%FCS
HOS TE 85 in DMEM
+ 10% FBS
None
Human Foreskin
Fibroblasts (Chinese)
In DMEM +10% FCS
3-aminotriazole (3-AT)
(80 mM to inhibit
catalase)
Pb chromate induced foci of morphological transformation Sidhu et al. (1991)
after repeated exposure and passaging.
Pb chromate did not induce anchorage independence, but
cells from the foci obtained during morphological
transformation.
Pb chromate did not induce neoplastic transformation in the
cells from the foci obtained during morphological
transformation.
Studied as a chromate compound. Role of Pb not mentioned
or considered.
Pb acetate-induced concentration-dependent increase in Hwua and Yang
anchorage independence. Anchorage independence not (1998)
affected by 3-AT.
-------
Table AX5-6.3. Genotoxic/Carcinogenic Effects of Lead—Carcinogenesis Animal Cell Cultures
X
Compound
Pb acetate
Pb chloride
Pb chromate
Pb chromate
Dose and Duration
Morphological Transformation
(10-50 uM for 48 h)
Morphological Transformation
(doses not given)
Enhancement of Simian
Adenovirus (SA7) induced
morphological transformation.
(80-1,240 uM for 20 h)
Morphological Transformation
(10-50 uM for 24 h)
Cell Type
Primary SHE cells in
AMEM + 10% FBS
C3H10T1/2 cells in
EMEM +10% FBS
Primary SHE cells in
DMEM + 10% FBS
C3H10T1/2 cells in
EMEM + 10% FBS
Co-exposure Effects
None Pb acetate was weakly positive inducing a 0.19-1.6%
increase in transformation. There was a weak dose
response. There were no statistical analyses of these data.
None Pb chloride did not induce morphological transformation.
None Pb chromate enhanced SA7-induced morphological
transformation.
Studied as a chromate compound. Role of Pb not
mentioned or considered.
None Pb chromate induced morphological and neoplastic
transformation.
Reference
Zelikoffetal. (1988)
Patierno et al. (1988),
Patierno and
Landolph (1989)
(both papers present
the same data)
Schechtman et al.
(1986)
Patierno et al. (1988)
Patierno and
Anchorage Independence for cells
isolated during morphological
transformation
Neoplastic Transformation for cells
isolated during morphological
transformation.
Landolph (1989)
Cells exhibiting morphological transformation grew in soft choth racers cresent
agar and grew in nude mice. the sam£ data)
Studied as a chromate compound.
Pb chromate
(and pigments
containing Pb
chromate)
Morphological Transformation
(0.04-8 ng/mL as Cr for 7 days)
Anchorage Independence for cells
isolated during morphological
transformation
Neoplastic Transformation for cells
isolated during morphological
transformation
Primary SHE cells in
DMEM + 10% FCS
None Pb chromate induced morphological and neoplastic
transformation.
Cells exhibiting morphological transformation grew in soft
agar and grew in nude mice.
Studied as a chromate compound.
Elias et al. (1989)
Pb chromate Morphological Transformation Primary SHE cells in
(0.02-0.88 ug/mL as Cr for 7 days) DMEM + 10% FCS
None Pb chromate induced morphological transformation more Elias et al. (1991)
potently (9-fold) than other chromate compounds.
-------
Table AX5-6.3 (cont'd). Genotoxic/Carcinogenic Effects of Lead—Carcinogenesis Animal Cell Cultures
Compound
Dose and Duration
Cell Type
Co-exposure
Effects
Reference
Pb nitrate Morphological Transformation
(0.04-8 ug/mL as Cr for 7 days)
Primary SHE cells in
DMEM + 10% PCS
Calcium chromate Pb nitrate alone did not induce significant levels of
transformation.
Pb nitrate plus calcium chromate increased the potency of
calcium chromate to that of Pb chromate. Data suggest Pb
ions are synergistic with chromate ions in inducing
neoplastic transformation.
Elias et al. (1991)
X
oo
o
Abbreviations
Cells
SHE—Syrian hamster embryo;
C3H10T/12 cells are a mouse embryo cell line
Medium and Components
AMEM—Alpha Minimal Essential Medium;
DMEM—Dulbecco's Minimal Essential Medium;
EMEM—Eagle's Minimal Essential Medium;
FBS—Fetal Bovine Serum
ECS—Fetal Calf Serum
H-MEM—Minimum essential medium/nutrient mixture-F12-Ham
HOS TE—Human osteosarcoma cell line TE
Differences between the serum are unclear as insufficient details are provided by authors to distinguish.
-------
Table AX5-6.4. Genotoxic/Carcinogenic Effects of Lead—Genotoxicity Laboratory Animal Studies.
Compound
Pb acetate
Dose and Duration
2.5 mg/100 g given i.p.
as daily injection for 5—
15 days
Species
Female Norway Rat
Co-exposure
Selenium (0.012-
0.047 mg/lOOg or
0.094-0. 188 mg/100 g
given i.p. with Pb)
Effects
Pb induced chromosome damage after chronic treatment. It
was not dose dependent as only 1 dose was studied. The
effects of selenium on Pb effects are unclear as selenium
alone induced substantial chromosome damage.
Reference
Chakraborty
etal. (1987)
10-20 mg/100 g given i.p.
as single injection and
animals studied after
15 days
5 animals per group.
Chromosome damage in
bone marrow
The single dose exposure also induced chromosome damage,
but untreated controls were not done in this regimen. There
is some mention that this dose regimen is toxic to the animals
as selenium modulated the lethal effects, but no explanation
of how many animals died.
X
-------
Table AX5-6.4 (cont'd). Genotoxic/Carcinogenic Effects of Lead—Genotoxicity Laboratory Animal Studies.
Compound
Dose and Duration
Species
Co-exposure
Effects
Reference
Pb nitrate
X
oo
to
Pb nitrate
Pb nitrate
100-200 mg/kg given i.v.
on 9th day of gestation
onwards for 9 days.
Mothers and fetuses
analyzed on G18.
Group size not given.
Resorptions, fetal viability
and chromosome damage,
SCE and NOR in the
mother and fetus were
examined. Mother-bone
marrow; fetus liver or lung
3 mothers and fetuses per
dose were analyzed.
10, 20, or 40 mg/kg given
i.p. 24 h
6 animals per group.
Chromosome damage and
Mitotic Index in bone
5, 10, or 20 mg/kg given
i.p. 24 h
6 animals per group.
Chromosome damage in
bone marrow.
50 metaphases per animal
for a total of 300 (X6).
ICR Swiss Webster Mice,
6-8 wk old
Swiss Albino Mice,
8 wks old
Swiss Albino Mice,
8 wks old
None
Phyllanthus fruit extract
(685 mg/kg) or ascorbic
acid (16.66 mg/kg)
given by gavage for
7 days
Ferric chloride
(18 mg/kg) given i.p.
for 24 h administered
1 h before, 1 h after, or
together with Pb nitrate
Pb levels were found in both mother and fetus indicating no
problems crossing the placenta.
All doses indicated increased resorption and decreased
placental weights. No effects on fetal weight.
Significant increase in SCE in mothers at 150 and 200 mg/kg.
No increase in SCE in fetuses.
Significant decrease in NOR in both mother and fetuses.
No gaps or breaks in mothers or fetuses.
Some weak aneuploidy at lowest dose.
Some karyotypic chromosome damage was seen.
No explanation of how many cells analyzed per animal
(3 animals per dose were analyzed) as only 20— 40 cells were
analyzed.
There was no dose response and no statistical analyses for
chromosome damage. No details on how many animals
analyzed for metaphase damage or how many cells per
animal.
Data interpretation is also complicated as too few metaphases
were analyzed 10—25 for SCE. Not given for CA.
No detail on potential maternal toxicity.
Pb nitrate increased the amount of chromosome damage at
each dose. But there was no dose response and a similar
level of damage was seen for each dose.
Phyllanthus fruit extract reduced the amount of damage at
each dose. Ascorbic acid reduced the damage at the lowest
dose but increased it at the higher doses.
Higher concentrations of Pb nitrate reduced the mitotic index.
This effect was reversed by ascorbate and Phyllanthus only at
the moderate dose.
Pb nitrate increased the amount of chromosome damage in a
dose-dependent manner.
Iron exhibited some modifications of Pb induced damage:
If administered 1 h before Pb plus simultaneously it reduced
the damage. If administered with Pb only at same time it
reduced damage in the lower doses. If Pb was started 1 h
before iron there was no effect.
Thus iron may antagonize Pb perhaps by blocking uptake.
Nayaketal. (1989b)
Dhiretal. (1990)
Dhiretal. (1992a)
-------
Table AX5-6.4 (cont'd). Genotoxic/Carcinogenic Effects of Lead—Genotoxicity Laboratory Animal Studies.
X
oo
Compound
Pb nitrate
Pb nitrate
Pb nitrate
Pb nitrate
Pb nitrate
Dose and Duration Species
5 or 10 mg/kg given by Swiss Albino Mice,
gavage for 24 h 7-8 wks old
6 animals per group.
Chromosome aberrations in
bone marrow
10, or 20 mg/kg given i.p. Swiss Albino Mice,
48 h 6 wks old
12 animals per group.
Micronucleus formation in
bone marrow
10, 20, or 40 mg/kg given Swiss Albino Mice,
i.p. 24 h 6-8 wks old
5 animals per group.
SCE in bone marrow
0.625-80 mg/kg given i.p. Swiss Albino Mice,
for 12, 24 or 36 h 6-8 wks old
12 animals per group
Micronucleus formation in
bone marrow. 4000
erythorocytes scored per
animal
0.7-89.6 mg/kg given by Swiss Albino Mice,
gavage for 24, 48, or 72 h, 4 wks old
Co-exposure
Zirconium oxychloride
(110 or 220 mg/kg)
given by gavage for
24 h administered 2 h
before, 2 h after or
together with Pb nitrate
Phyllanthus fruit extract
(685 mg/kg) or ascorbic
acid (16.66 mg/kg)
given by gavage for
7 days
Phyllanthus fruit extract
(685 mg/kg) or ascorbic
acid (16.66 mg/kg)
given by gavage for
/ days
None
None
Effects
Pb nitrate increased the amount of chromosome damage in a
dose-associated manner.
Zirconium induced a dose-associated increase in
chromosome damage.
Zirconium exhibited minimal modification of Pb nitrate-
induced damage when administered 2 h before or after Pb
nitrate.
Administering the two together increased the damage.
Pb nitrate increased the amount of micronuclei at both doses
in a dose-associated manner. The 48 h recovery time was
lower than 24 h but still elevated.
Phyllanthus fruit extract reduced the amount of damage at
both doses. Ascorbic acid reduced the damage at the lowest
dose but increased it at the higher dose.
Pb nitrate increased the amount of SCE in a dose-dependent
manner. Pb nitrate had no effect of the proliferative rate
index (consideration of metaphases in different division
numbers)
Phyllanthus fruit extract and ascorbic acid reduced the
amount of damage at each dose.
Pb nitrate induced micronuclei but they did not increase with
dose.
Pb induced more micronuclei in males than in females.
The ratio of polychromatic to normochromatic erythrocytes
was elevated in Pb nitrate treated cells, but again did not
increase with dose.
Viability was high (92-96%) at all doses.
Ph nitratp infhirpH sirmlp stranH hrpaVs hilt thpv HiH not
Reference
Dhiretal. (1992b)
Roy et al. (1992)
Dhiretal. (1993)
Jagetia and Aruna
(1998)
Devi et al. (2000)
or 1 or 2 wks
5 animals per group.
Cell viability by trypan blue
Single strand breaks in
white blood cells
increase with dose. In fact the 3 highest doses were all
similar in magnitude and less than the 5 lowest doses.
The 5 lowest doses were also similar in magnitude.
-------
Table AX5-6.4 (cont'd). Genotoxic/Carcinogenic Effects of Lead—Genotoxicity Laboratory Animal Studies.
Compound
Pb acetate
Dose and Duration Species
10 mg/kg given by gavage Male Wistar rats,
5 times a week for 4 wks. 30 days old
10 animals per group
Chromosome Aberrations
with 20 metaphases scored
per animal
Co-exposure Effects
Cypermethrin No effects on weight gain.
Pb acetate induced an increase in aneuploidy, and the percent
of cells with damage, but did not increase structural damage
or alterations in organ weight.
Cypermethrin and Pb together increased structural
aberrations that were predominately acentric fragments.
However, this was compared to untreated controls and not the
individual treatments. Considering the individual treatments,
the two together are less than additive.
Reference
Nehez et al. (2000)
X
-------
Table AX5-6.5. Genotoxic/Carcinogenic Effects of Lead—Genotoxicity Human Cell Cultures Mutagenesis
Compound
Dose and Duration
Cell Type
Co-exposure
Effects
Reference
X
-------
Table AX5-6.6. Genotoxic/Carcinogenic Effects of Lead—Genotoxicity Human Cell Cultures Clastogenicity
X
oo
Compound
Pb chromate
Pb chromate
Pb chromate
Assay (Concentration
and Exposure Time)
Chromosome aberrations
(0.08-2 ug/cm2 for 24 h)
Chromosome aberrations
(0.1-5 |ig/cm2 for 24 h)
Chromosome aberrations
(0.1-5 |ig/cm2 for 24 h)
Cell Type and Culture
Medium
Human Foreskin Fibroblasts
(Caucasian) in EMEM + 15% FBS
Primary Human Lung Cells in
DMEM/F12 + 15%FBS
Primary Human Lung Cells and
WTHBF-6 — human lung cells with
Co-exposure Effects
None Pb chromate induced chromosome damage in a
concentration dependent manner.
This study was focused on chromate.
None Pb chromate induced chromosome damage in a
concentration dependent manner.
This study was focused on chromate.
None Pb chromate induced chromosome damage in a
concentration dependent manner. Effects were similar in
Reference
Wise et al.
(1992)
Wise et al.
(2002)
Wise et al.,
(2004a)
Pb chromate
Pb chromate
Pb chromate
Chromosome aberrations
(0.1-5ug/cm2for24h)
Chromosome aberrations
(0.05-5 ug/cm2 for 24 h)
Chromosome aberrations
(0.05-5 jig/cm2 for 24 h)
hTERT in DMEM/F12 + 15% FBS
WTHBF-6—human lung cells with
hTERT in DMEM/F12 + 15% CCS
WTHBF-6—human lung cells with
hTERT in DMEM/F12 + 15% CCS
WTHBF-6—human lung cells with
hTERT in DMEM/F12 + 15% CCS
Vitamin C
(2mM
co-exposure
for 24 h)
Vitamin C
(2mM
co-exposure
for 24 h)
None
both cell types establishing the WTHBF-6 cells as a useful
model.
This study was focused on chromate.
Pb chromate induced chromosome damage in a Xie et al. (2004)
concentration dependent manner.
Vitamin C blocked Cr ion uptake and the chromosome
damage after Pb chromate exposure.
This study was focused on chromate.
Pb chromate induced chromosome damage in a Wise et al.
concentration dependent manner. (2004b)
This study was focused on showing chromate and not Pb
ions were the clastogenic species.
Pb chromate induced chromosome damage in a Wise et al.
concentration dependent manner. (2005)
This study was focused on comparing particulate chromate
compounds.
-------
Table AX5-6.6 (cont'd). Genotoxic/Carcinogenic Effects of Lead—Genotoxicity Human Cell Cultures Clastogenicity
Compound
Assay (Concentration
and Exposure Time)
Cell Type and Culture
Medium
Co-exposure
Effects
Reference
Pb glutamate
Pb glutamate
Pb ion uptake-ICPMS
(250-2,000 uM for 24 h)
Chromosome Aberrations
(250-2,000 uM for 24 h)
Pb ion uptake-ICPMS
(250-2,000 uM for 24 h)
Mitotic Index
(250-2,000 uM for 24 h)
Growth Curve
(250-2,000 uM for 24 h)
Cell cycle Analysis
(250-2,000 uM for 24 h)
WTHBF-6—human lung cells with
hTERT in DMEM/F12 + 15% CCS
WTHBF-6—human lung cells with
hTERT in DMEM/F12 + 15% CCS
None Pb glutamate induced a concentration-dependent increase in Wise et al.
intracellular Pb ions. (2005)
Pb glutamate did not induce chromosome damage.
None Pb glutamate induced a concentration-dependent increase in
intracellular Pb ions.
Pb glutamate increased the mitotic index, but inhibited
growth and did not induce chromosome damage.
X
1
oo
Radioactive Pb
ions
No further
specification
Abbreviations
LET = 13,600keV/|iM Human Foreskin Fibroblasts in
Fluenceof DF-12 + 10%FCS
2 x 106 particles/ cm2
Chromosome Aberrations
None Pb induced chromosome damage that recurred
with time and cell passaging. Analysis limited to
—25 metaphases.
Focused on radioactive effects of Pb
Martins et al.
(1993)
hTERT is the catalytic subunit of human telomerase
Medium and Components
EMEM—Eagle's Minimal Essential Medium
DMEM/F12—Dulbecco's Minimal Essential Medium/Ham's F12
CCS—Cosmic Calf Serum
FBS—Fetal Bovine Serum
FCS—Fetal Calf Serum
Differences between the serum types are unclear as insufficient details are provided by authors to distinguish.
-------
Table AX5-6.7. Genotoxic/Carcinogenic Effects of Lead—Genotoxicity Human Cell Cultures DNA Damage
X
oo
oo
Compound
Pb acetate
Pb acetate
Pb chromate
Pb chromate
Pb acetate
Assay (Concentration and
Exposure Time)
DNA strand breaks as nucleiod
sedimentation (500 uM for 20—
25 h)
DNA strand breaks as nucleoid
sedimentation assay (100 uM
for 30 min^t h)
DNA adducts (0.4-0.8 ug/cm2
for 24 h)
DNA double strand breaks
(0.1-5 ug/cm2 for 24 h) by
Comet assay and H2A.X foci
formation
DNA strand breaks and DNA
protein crosslinks and oxidative
Cell Type and
Culture Medium
HeLa Cells in AMEM
+ 5% FBS
HeLa Cells in
HEPES/
glucose buffer
Primary Human Small
Airway Cells in
Clonetics growth
medium
WTHBF-6— human
lung cells with
hTERT in
DMEM/F12 + 15%
CCS
Primary lymphocytes
in RPMI 1640 without
Co-exposure
None
See also Table
AX5-6.16
Buthionine
sulfoximine (BSO) to
deplete cells of thiols
None
None
Vitamins A (10 uM),
C (10 uM), E
Effects
Pb acetate alone did not induce single strand breaks.
Pb acetate did not induce DNA strand breaks.
Pb chromate induced Pb inclusion bodies and Cr-DNA adducts and
Pb-DNA adducts in a concentration-dependent manner.
Pb chromate induced DNA double strand breaks in a concentration
dependent manner.
This study showed the damage was due to chromate and not Pb.
Pb acetate induced an increase in DNA single strand breaks at 1 uM
that went down with increasing dose. The highest concentration was
Reference
Hartwig et al.
(1990)
Snyder and
Lachmann
(1989)
Singh et al.
(1999)
Xie et al.
(2005)
Wozniak and
Blasiak (2003)
lesions by comet assay (1—
100 uM for 1 h)
(25 uM), calcium
chloride (100 uM)
magnesium chloride
(100 uM) or zinc
chloride (100 uM)
significantly less than the damage in untreated controls. For double
strand breaks, all concentrations had more damage than the controls,
but there was less damage in the highest concentrations than the two
lower ones. Pb only induced a slight increase in the amount of DNA-
protein crosslinks at the highest concentration.
Co-exposure to magnesium had no effect. Co-exposure to vitamins A,
C, and E or zinc exacerbated the DNA single strand break effects at the
highest concentration. Co-exposure to calcium exacerbated the single
strand break effect at all concentrations.
-------
Table AX5-6.7 (cont'd). Genotoxic/Carcinogenic Effects of Lead—Genotoxicity Human Cell Cultures DNA Damage
Compound
Pb nitrate
Assay (Concentration and
Exposure Time)
DNA-protein crosslinks by
SDS precipitation
(l-10mMfor6h)
Cell Type and
Culture Medium Co-exposure
Human Burkitt's None
lymphoma cells-EBV
transformed in RPMI
1640 + 10% PCS
Effects
Pb nitrate did not induced DNA protein crosslinks. Independent
samples were analyzed by 5 different laboratories.
Reference
Costa et al.
(1996)
X
Abbreviations
hTERT is the catalytic subunit of human telomerase.
Medium and Components
AMEM—Alpha Minimal Essential Medium;
EMEM—Eagle's Minimal Essential Medium;
DMEM/F12—Dulbecco's Minimal Essential Medium/Ham's F12;
FBS—Fetal Bovine Serum
FCS—Fetal Calf Serum
Differences between the serum types are unclear as insufficient details are provided by authors to distinguish.
oo
VO
-------
Table AX5-6.8. Genotoxic/Carcinogenic Effects of Lead—Genotoxicity Animal Cell Cultures Mutagenicity
Compound
Assay and Duration
Cell Type
Co-exposure
Effects
Reference
Pb acetate Cytotoxicity (1-25 uM for 24 h) V79 in AMEM + 10% None
Mutagenesis—HPRT (0.5-5 uM for 44 h) FBS See also
Table AX5-6.16
LC50 = 3 uM
Pb acetate alone was not mutagenic.
Hartwig et al.
(1990)
X
Pb acetate Cytotoxicity (0.5-2000 uM for 5 days) G12-CHV79 cells See also Table
—insoluble Mutagenesis—gpt (0.5-1700 uM for 5 days) with 1 COPY gPl §ene AX5-6.17
precipitate at high in Ham's F12 + 5%
dose. FBS
Pb chloride
Pb chloride
Pb chloride
Pb chromate
Pb chromate
Cytotoxicity (0. 1-1 uM for 1 h)
Mutagenicity — gpt assay
(0.1-1 uMfor Ih)
Cytotoxicity (0. 1-1 uM for 1 h)
Mutagenicity — gpt assay
(0.1-1 uMfor Ih)
Mutagenicity — gpt assay
(0.1-1 uMfor Ih)
PCR/Southern to analyze mutants for
sequence
Cytotoxicity (10-100 uM for 24 h)
HGPRT assay (10-100 uM for 24 h)
Mutagenicity as Sodium/potassium ATPase
(ouabain resistance) or 6-thioguanine
resistance (25-100 uM for 5 h)
AS52-CHO-gpt, lack None
hprt in HBSS
followed by Ham's
F12+ 5% FBS
AS52-CHO-gpt, lack Allopurinol (50 uM)
hprt in HBSS to inhibit xanthine
followed by Ham's oxidase
F12+ 5% FBS
AS52-CHO-gpt, lack None
hprt in HBSS
followed by Ham's
F12+ 5% FBS
V79 CHL-HPRT low NTA
clone in MEM + 10%
FCS
C3H10T1/2 cells in None
EMEM + 10% FBS
LC50 = 1700 uM
Pb acetate was mutagenic, but only at toxic
concentration (1700 uM) where precipitate formed
not at lower concentrations (500 or 1000 uM).
There were no statistical analyses of these data.
LC74 = 1 uM (maximum concentration tested)
Pb chloride induced a dose-dependent increase in
the number of 6 thioguanine resistant mutants.
Did not adjust and compare as previous studies.
LC74 = 1 uM. Allopurinol had no effect on
Cytotoxicity.
Pb chloride was mutagenic (0.8 and 1 uM).
Allopurinol reduced mutagenesis.
Pb chloride (0.1—0.4 uM) caused mostly point
mutations. Higher concentrations (0.5—1 uM)
caused more deletions.
There were no statistical analyses of these data.
Usually examined fewer mutations than control.
Mutagenesis was assessed with HGPRT assay. Pb
chromate was not mutagenic.
Co-exposure to NTA caused Pb chromate to
become mutagenic through increased solubilization.
This mutagenic effect was completely attributed to
the Cr(VI) ions.
Pb chromate was not mutagenic.
Roy and Rossman
(1992)
Arizaetal. (1996)
Arizaetal. (1998)
Ariza and Williams
(1999)
Celotti et al. (1987)
Patierno et al.
(1988) and Patierno
and Landolph
(1989) (both papers
present the same
data)
-------
Table AX5-6.8 (cont'd). Genotoxic/Carcinogenic Effects of Lead—Genotoxicity Animal Cell Cultures Mutagenicity
Compound
Pb nitrate
Precipitate at 1000
uM and higher.
Pb nitrate
-no insoluble
precipitate
Pb sulfide
Assay and Duration
Cytotoxicity (50-5,000 uM for 5 days)
Mutagenesis at HPRT locus
(50-2,000 uM for 5 days)
Cytotoxicity (0.5-2000 uM for 5 days)
Mutagenesis — gpt (0.5—1700 uM for 5 days)
Cytotoxicity (100-1,000 uM for 24 h)
Mutagenicity at HPRT locus
Cell Type
V79 CHL-HPRT low
clone in Ham's F12
+10% FBS
G12-CHV79 cells
with 1 copy gpt gene
in Ham's F 12 + 5%
FBS
V79 CHL-HPRT low
clone in Ham's F12
Co-exposure
None
See also Table
AX5-6.17
None
Effects
LC50 = 2950 uM
Pb nitrate was mutagenic at 500 uM, but there was
no dose response as higher doses less mutagenic
though still 2— 4-fold higher. There were no
statistical analyses of these data.
LC 50 = 1500 uM
Pb nitrate was not mutagenic. There were no
statistical analyses of these data.
LC50 = 580 uM; did not increase with longer
exposures.
Reference
Zelikoff etal.
(1988)
Roy and Rossman
(1992)
Zelikoff etal.
(1988)
(100-1,000 uM for 24 h)
+10% FBS
Mutagenic at 376 and 563 uM. Not mutagenic
lower or higher. Suggested Cytotoxicity prevented
mutagenesis at higher concentrations. There were
no statistical analyses of these data.
X
Abbreviations
V79 are a Chinese Hamster Lung Cell Line;
G12-CHV79 are derived from V79;
CHO are a Chinese Hamster Ovary Cell Line ;
AS52 are derived from CHO;
C3H10T/12 cells are a mouse embryo cell line
Medium and Components
AMEM—Alpha Minimal Essential Medium;
EMEM—Eagle's Minimal Essential Medium;
HBSS—Hank's Balanced Salt Solution
FBS—Fetal Bovine Serum
FCS—Fetal Calf Serum
Differences between the serum types are unclear as insufficient details are provided by authors to distinguish.
-------
Table AX5-6.9. Genotoxic/Carcinogenic Effects of Lead—Genotoxicity Animal Cell Cultures Clastogenicity
Compound
Pb chromate
Pb chromate
Pb chromate
X
\Q Pb chromate
to
Pb glutamate
Pb nitrate
Pb nitrate
Pb nitrate
Assay (Concentration and
Exposure Time)
Chromosome Aberrations
(0.4-8 |ig/cm2 for 24 h)
Chromosome Aberrations
(0.8-8 |ig/cm2 for 24 h)
Chromosome Aberrations
(0.8or8ug/cm2for24h)
Chromosome Aberrations
(0.8-8 |ig/cm2 for 24 h)
Chromosome Aberrations
(500-2,000 uM for 24 h)
Chromosome Aberrations
(500-2,000 uM for 24 h)
Insoluble precipitate at all
concentrations
Chromosome Aberrations
(3-30 uM for 2 h +16 h recovery)
Chromosome aberrations
(0.05-1 uM for 3-12 h)
Cell Type and Culture
Medium
Chinese Hamster Ovary AA8
cells in AMEM + 10% FBS
Chinese Hamster Ovary AA8
cells in AMEM + 10% FBS
Chinese Hamster Ovary AA8
cells in AMEM + 10% FBS
Chinese Hamster Ovary AA8
cells in AMEM + 10% FBS
Chinese Hamster Ovary AA8
cells in AMEM + 10% FBS
Chinese Hamster Ovary AA8
cells in AMEM + 10% FBS
Chinese Hamster Ovary cells
in EMEM + 10% FBS
Chinese Hamster Ovary AA8
cells in DMEM+10%NCS
Co-exposure
None
Vitamin C (1 mM for
24 h as co-exposure to
block Cr uptake)
Vitamin E (25 uM as
pretreatment for 24 h)
Vitamin C (1 mM as
pretreatment for 24 h)
Vitamin E (25 uM as
pretreatment for 24 h)
Vitamin E (25 uM as
pretreatment for 24 h)
Vitamin E (25 uM as
pretreatment for 24 h)
None
Crown ethers to
modify effect through
chelation and uptake
Effects
Pb chromate induced chromosome damage in a
concentration dependent manner.
This study was focused on chromate.
Pb chromate induced chromosome damage in a
concentration dependent manner. This effect and uptake
of Cr ions were blocked by vitamin C.
This study was focused on chromate.
Pb chromate induced chromosome damage in a
concentration dependent manner. Vitamin E blocked
clastogenic activity of Pb chromate, but had no effect on
other Pb compounds.
This study found that the chromosome damage was
mediated by chromate ions and not Pb ions
Pb chromate induced chromosome damage in a
concentration dependent manner. Vitamins C and E
blocked clastogenic activity of Pb chromate.
This study was focused on chromate.
Pb glutamate induced chromosome damage at 1 mM but
not at higher or lower concentrations.
Vitamin E did not modify this effect.
Pb nitrate did not induce chromosome damage.
Pb nitrate did not induce chromosome damage.
Pb nitrate did not induce chromosome damage.
Reference
Wise et al.
(1992)
Wise et al.
(1993)
Wise et al.
(1994)
Blankenship
etal. (1997)
Wise et al.
(1994)
Wise et al.
(1994)
Lin et al.
(1994)
Cai and
Arenaz
(1998)
-------
Table AX5-6.9 (cont'd). Genotoxic/Carcinogenic Effects of Lead—Genotoxicity Animal Cell Cultures Clastogenicity
X
Compound
Pb acetate
Pb acetate
Pb nitrate
Pb nitrate
Pb nitrate
Assay (Concentration and
Exposure Time)
SCE (1-10 uM for 26 h+)
Micronucleus assay
(0.01-10 uM for 18 h)
SCE Formation (500-3,000 uM for
24 h)
Precipitate at 1000 uM and higher.
Micronucleus formation
(3-30 uM for 2 h +16 h recovery)
SCE (3-30 uM for 2 h +16 h recovery)
SCE (0.05-1 uM for 3-12 h)
Cell Type and Culture
Medium
V79 in AMEM + 10% FBS
Chinese Hamster V79 cells in
DMEM + 10% FCS
V79 CHL-HPRT low clone in
Ham's F12 +10% FBS
CHO cells in EMEM + 10%
FBS
CHO AA8 in DMEM +10%
NCS
Co-exposure
None
See also
Table AX5-6. 17
None
None
None
Crown ethers to
modify effect
through chelation
and uptake
Effects
Pb acetate alone did not induce SCE. Only 25 cells per
treatment analyzed.
Pb acetate induced an increase in micronuclei that
increased with concentration and reached a plateau.
Two experiments were done and presented separately as a
Figure and a Table. The magnitude of the effects was
small to modest and statistics were not done.
No SCE. Only 30 cells analyzed per treatment.
Pb nitrate did not induce micronuclei formation
Pb nitrate induces a concentration-dependent increase in
SCE (3, 10, 30 uM).
Pb nitrate caused a weak concentration-dependent
increase in SCE. These data were not statistically
analyzed. The effect was reduced by a crown ether
probably because a similar reduction was seen in
Reference
Hartwig
etal. (1990)
Bonacker
et al. (2005)
Zelikoff
etal. (1988)
Lin et al.
(1994)
Cai and
Arenaz
(1998)
spontaneous SCE.
-------
Table AX5-6.9 (cont'd). Genotoxic/Carcinogenic Effects of Lead—Genotoxicity Animal Cell Cultures Clastogenicity
Compound
Pb sulfide
Assay (Concentration and
Exposure Time)
SCE Formation
(100-1,000 uM for 24 h)
Cell Type and Culture
Medium
V79 CHL-HPRT low clone in
Ham's F12 +10% FBS
Co-exposure
None
Effects
No SCE. Only 30 cells analyzed per treatment.
Reference
Zelikoffetal.
(1988)
Abbreviations
V79 are a Chinese Hamster Lung Cell Line;
CHO are a Chinese Hamster Ovary Cell Line ;
Medium and Components
AMEM—Alpha Minimal Essential Medium;
DMEM—Dulbecco's Minimal Essential Medium;
EMEM—Eagle's Minimal Essential Medium;
. HBSS—Hank's Balanced Salt Solution
t*j FBS—Fetal Bovine Serum
£; FCS—Fetal Calf Serum
JQ NCS—Newborn Calf Serum
4^
Differences between the serum types are unclear as insufficient details are provided by authors to distinguish.
-------
Table AX5-6.10. Genotoxic/Carcinogenic Effects of Lead—Genotoxicity Animal Cell Cultures DNA Damage
X
Compound
Pb acetate
Pb acetate
Assay (Concentration
and Exposure Time) Cell Type and Culture Medium Co-exposure
DNA damage as alkaline V79 CHL-HPRT low clone in Ham's None
elution (exposure time and F12 +10% FBS
dose not given)
Precipitate at 1000 uM and
higher.
DNA strand breaks as nick G12-CHV79 cells with 1 copy gpt See also Table
translation (1700 uM for gene in Ham's F12 + 5% FBS AX5-6.17
5 days)
Or supercoiled relaxation
(1000 uM for 5 days)
Insoluble precipitate at high
dose.
Effects
No DNA damage (Single strand breaks, DNA-
protein crosslinks or DNA-DNA crosslinks).
However, the data was not shown
Pb acetate did not induce SSB. Pb acetate
(1700 uM) did increase nick translation when an
exogenous polymerase was added. There were no
statistical analyses of these data.
Reference
Zelikoff etal. (1988)
Roy and Rossman
(1992)
Pb chromate
Pb chromate
Pb nitrate
DNA damage as alkaline
elution (0.4—8 ug/cm for
24 h plus 24 recovery)
Chinese Hamster Ovary AA8 cells in
AMEM + 10% FBS
None
DNA adducts
(0.8or8ng/cm2for24h)
DNA Protein Crosslinks as
SDS precipitation
(50-5,000 uM for 4 h)
Chinese Hamster Ovary AA8 cells in
AMEM + 10% FBS
Novikoff ascites hepatoma cells
Vitamin C (1 mM as
pretreatment for 24 h)
Vitamin E (25 uM as
pretreatment for 24 h)
None
Pb chromate induced DNA single strand breaks in Xu et al. (1992)
a concentration dependent manner, which were all
repaired by 24 h post-treatment.
Pb chromate induced DNA protein crosslinks in a
concentration dependent manner, which persisted
at 24 h post-treatment.
Pb chromate did not induce DNA-DNA
crosslinks.
This study was focused on chromate.
Pb chromate induced DNA adducts in a Blankenship et al.
concentration dependent manner. Vitamins C and (1997)
E blocked DNA adducts induced by Pb chromate.
This study was focused on chromate.
Pb nitrate induced DNA protein crosslinks in a Wedrychowski et al.
concentration dependent manner. (1986)
-------
Table AX5-6.10 (cont'd). Genotoxic/Carcinogenic Effects of Lead—Genotoxicity Animal Cell Cultures DNA Damage
Compound
Pb nitrate
Assay (Concentration and
Exposure Time)
DNA strand breaks as nick
translation (1700 uM for 5 days)
Cell Type and Culture
Medium
G12-CHV79 cells with 1 copy
gpt gene in Ham's F12 + 5%
FBS
Co-exposure
See also Table
AX5-6.17
Effects
Pb nitrate (1700 uM) did increase nick translation when an
exogenous polymerase was added. There were no statistical
analyses of these data.
Reference
Roy and Rossman
(1992)
Abbreviations
G12-CHV79 are derived from V79;
V79 are a Chinese Hamster Lung Cell Line;
CHO are a Chinese Hamster Ovary Cell Line ;
Medium and Components
AMEM—Alpha Minimal Essential Medium;
FBS—Fetal Bovine Serum
FCS—Fetal Calf Serum
Differences between the serum types are unclear as insufficient details are provided by authors to distinguish.
X
-------
X
Table AX5-6.11. Genotoxic/Carcinogenic Effects of Lead—Genotoxicity Non-mammalian Cultures
Compound
Assay and Concentration
Cell Type
Co-exposure
Effects
Reference
Pb chromate
(and 13
pigments
containing Pb
chromate)
Mutation Frequency (50—500 ug/plate)
Anchorage Independence for cells isolated
during morphological transformation
Neoplastic Transformation for cells
isolated during morphological
transformation
Salmonella
typhimurium +/- S9
fraction
Nitrilotriacetic acid
(NTA to dissolve
insoluble compounds)
and Silica
Encapsulation
Pb chromate and its related pigments did not induce
mutagenicity.
A few did when dissolved in NTA.
Encapsulation prevented mutagenesis in those that
were positive when dissolved in NTA.
S9 had no effect.
Studied as a chromate compound.
Connor and Pier
(1990)
-------
X
Table AX5-6.12. Genotoxic/Carcinogenic Effects of Lead—Genotoxicity as it Pertains to Potential Developmental Effects
Compound
Assay and Concentration
Species
Co-exposure
Effects
Reference
Pb acetate 25^100 mg/kg given i.p as single injection Male Swiss Mice— None
and animals studied after 24 h 9—12 wks old
Sperm morphology
Pb induced sperm head abnormalities at 50—
100 mg/kg. A lower dose was negative and higher
doses were not done.
Fahmy (1999)
Pb acetate 200 or 400 mg/kg given by gavage daily
for 5 days
5 animals per group
Sperm Morphology
Male Swiss Mice
9-12 wks old
Calcium chloride (40 or
80 mg/kg by gavage
daily for 3 days given
2 wks after Pb
exposure)
Pb induced sperm abnormalities at 200 and 400
mg/kg. A lower dose was negative and higher doses
were not done. Calcium appeared to block this effect.
Aboul-Ela (2002)
oo
-------
Compound
Table AX5-6.13. Genotoxic/Carcinogenic Effects of Lead—Genotoxicity as it Pertains to
Potential Developmental Effects—Children
Exposure Regimen
Species
Co-exposure
Effects
Reference
Pb chloride
Pb nitrate
X
Pb nitrate
Administered in drinking water
1.33g/Lfor6wks
12.5—75 mg/kg given i.v. on 9th day
of gestation for 9 days.
Mothers and fetuses analyzed on
G18.
5 animals per group
Resorptions, fetal viability, and
chromosome damage in the mother
and fetus were examined.
100-200 mg/kg given i.v. on 9th
day of gestation for 9 days.
Mothers and fetuses analyzed on
G18.
Group size not given.
Resorptions, fetal viability and
chromosome damage, SCE and
NOR in the mother and fetus were
examined. Mother-bone marrow;
fetus liver or lung
3 mothers and fetuses per dose were
analyzed.
Male NMRI
Mice—9 wks old
ICR Swiss Webster
Mice—6-8 wks old
Cyclophosphamide— Pb did not increase resorptions indicating no dominant lethal
120 mg/kg b.w. given mutagenic effect. Pb appeared to have a small, but statistically
i.p 7 days prior to start insignificant reduction in the number of resorptions.
of breeding Cyclophosphamide reduced live implants in female mice.
None
ICR Swiss Webster
Mice—6—8 wks old
None
12.5-50 mg/kg had no effect on resorption or fetal viability.
75 mg/kg demonstrated some increased resorption though
statistics were not done.
No chromosome damage was seen in untreated controls. A low
level 1-3 and 2-5 aberrations were seen in mothers and fetuses
respectively.
There was no dose response and no statistical analyses. Data
interpretation is also complicated as too few metaphases were
analyzed 20-40 total.
No descriptions of potential effects on maternal health parameters
or fetal weights.
No indication of how many animals included in the chromosomal
analysis.
Pb levels were found in both mother and fetus indicating no
problems crossing the placenta.
All doses indicated increased resorption and decreased placental
weights. No effects on fetal weight.
Significant increase in SCE in mothers at 150 and 200 mg/kg.
No increase in SCE in fetuses.
Significant decrease in NOR in both mother and fetuses.
No gaps or breaks in mothers or fetuses.
Some weak aneuploidy at lowest dose.
Some karyotypic chromosome damage was seen. No explanation
of how many cells analyzed per animal (3 animals per dose were
analyzed) as only 20—40 cells were analyzed.
There was no dose response and no statistical analyses for
chromosome damage. No details on how many animals analyzed
for metaphase damage or how many cells per animal.
Data interpretation is also complicated as too few metaphases
were analyzed 10—25 for SCE. Not given for CA.
No detail on potential maternal toxicity.
Kristensen et al.
(1993).
Nayak et al.
(1989a)
Nayak et al.
(1989b)
-------
Table AX5-6.14. Genotoxic/Carcinogenic Effects of Lead—Epigenetic Effects and Mixture Interactions—Animal
Compound
Exposure Regimen
Species
Co-exposure
Effects
Reference
>
X
o
o
Pb acetate
Pb nitrate
Pb nitrate
Pb nitrate
Administered as an i.p. injection of
100 nl/kg.
Animals were studied either 24 h
after a daily dose for 3 days or for
various times (5 min—48 h) after a
single dose.
Administered as an i.p. injection of
100 umol/kg.
Animals were studied either 24 h
after a daily dose for 3 days or for
various times (5 min—48 h) after a
single dose.
Administered as an i.p. injection of
100 umol/kg. Some rats were
partially hepatectomized.
Animals were studied 48 h after
injection.
Administered as an i.v. injection of
20, 50, or 100 umol/kg.
Animals were studied 24 h after
injection.
Male Wistar Rats-
10 wks old
Male Wistar Rats-
10 wks old
Male Sprague
Dawley rats
Male Fisher 344
rats—7 wks old
Actinomycin D
(0.8 mg/kg)
administered i.p. for
4 h before a single
dose of Pb acetate.
Actinomycin D
(0.8 mg/kg)
administered i.p. for
4 h before a single
dose of Pb acetate.
Partial Hepatectomy
2-methoxy-
4-aminobenzene to
induce P4501A2
or
3-methylcholanthrene
to induce 4501A1
Pb acetate induced GST-P, which required the cis element, GPEI Suzuki et al.
(GST-P enhancer I). (1996)
Actinomycin D blocked the effects indicating that regulation was
at the mRNA level.
Pb acetate induced c-jun, which exhibited three peaks of exposure
over 48 h.
Pb acetate was more potent than Pb nitrate.
Pb nitrate induced GST-P, which required the cis element, GPEI Suzuki et al.
(GST-P enhancer I). (1996)
Actinomycin D blocked the effects indicating that regulation was
the mRNA level.
Pb nitrate induced c-jun, which exhibited three peaks of exposure
over 48 h.
Pb nitrate was less potent than Pb acetate.
Pb nitrate induced GSH and GST 7-7 activity. Dock (1989)
Partial hepatectomy did not induce GSH or GST 7-7.
Pb nitrate selectively inhibited P4501A2 and its induction by 2- Degawa et al.
methoxy-4-aminobenzene at the mRNA and protein level in a (1993)
dose-dependent manner.
Pb nitrate had minimal effect on P4501A1 and its induction by 3-
methyl cholanthrene.
Pb nitrate did not affect microsomal activity.
Pb nitrate induced GST-P in a dose-dependent manner.
-------
Table AX5-6.15. Genotoxic/Carcinogenic Effects of Lead—Epigenetic Effects and Mixture Interactions—Human
>
X
Compound
Pb acetate
Pb nitrate
Pb nitrate
Assay (Concentration and
Exposure Time)
Tyrosine aminotransf erase
expression and activity
(0.3-10 uM for 24-48 h)
PKC activity: 10uMfor48h
EROD/MROD activity
(10-100 uM for 24 h)
NAD(P)H: quinone
oxidoreductase activity
(10-100 uM for 24 h)
Glutathione-S-transferase
Ya activity (10-100 uM for 24 h)
NAD(P)H: quinone
oxidoreductase activity
(25 uM for 24 h)
Glutathione-S-transferase Ya
activity (25 uM for 24 h)
Cell Type
and Culture
Medium
H4-IIE-C3—
human
hepatoma cells
in DMEM +
2. 5% ECS
Hepa Iclc7
wild type cells
in DMEM +
10% FBS
C12- AHR-
deficient Hepa
Iclc? cells in
DMEM + 10%
FBS
Co-exposure
Dexamethasone
(0.1 uMfor 16 h),
or calcium chloride
(10 uM) or genistein
(100 uM to block PKC
activity)
TCDD (0. 1 nM),
3-methyl cholanthrene
(0.25 uM), beta-
naptflavone (10 uM),
benzo(a)pyrene (1 uM)
TCDD(O.lnM),
3-methyl cholanthrene
(0.25 uM), beta-
naptflavone (10 uM),
benzo(a)pyrene (1 uM)
Effects
Pb acetate inhibited glucocorticoid -induction of tyrosine
aminotransferase in a time- and dose-dependent manner.
Co-treatment with calcium reduced the effects of Pb.
Co-treatment with genistein increased the effects of Pb.
Pb acetate decreases PKC activity and its translocation from the
cytosol to the particulate cellular fraction.
Pb did not affect EROD/MROD activity.
Pb reduced CYP1A1 induction by TCDD, 3-methyl cholanthrene,
beta-naptflavone, benzo(a)pyrene.
Pb increased NAD(P)H: quinone oxidoreductase activity
Pb increased NAD(P)H: quinone oxidoreductase activity induction by
TCDD, 3-methyl cholanthrene, beta-naptflavone, benzo(a)pyrene.
10 uM increased Glutathione-S-transferase Ya activity.
25 and 100 uM increased Glutathione-S-transferase Ya activity.
Pb nitrate did not affect Glutathione-S-transferase Ya induction by
TCDD, 3-methyl cholanthrene, beta-naptflavone, benzo(a)pyrene.
Pb nitrate did not increase NAD(P)H: quinone oxidoreductase and
Glutathione-S-transferase Ya activity
Pb increased NAD(P)H: quinone oxidoreductase activity induction by
TCDD, 3-methyl cholanthrene, beta-naptflavone, benzo(a)pyrene.
Pb did not affect Glutathione-S-transferase Ya induction by TCDD, 3-
methyl cholanthrene, beta-naptflavone, benzo(a)pyrene.
Reference
Tonner and Heiman
(1997)
Korashy and
El-Kadi (2004)
Korashy and
El Kadi (2004)
Abbreviations
Medium and Components
DMEM—Dulbecco's Minimal Essential Medium;
FBS—Fetal Bovine Serum
FCS—Fetal Calf Serum
Differences between the serum types are unclear as insufficient details are provided by authors to distinguish.
-------
>
X
Table AX5-6.16. Genotoxic/Carcinogenic Effects of Lead—Epigenetic Effects and Mixture
Interactions—DNA Repair—Human
Compound
Pb acetate
Assay (Concentration and
Exposure Time)
DNA strand breaks as nucleoid
sedimentation (500 uM for
20-25 h)
Cell Type
and Culture
Medium Co-exposure
HeLa Cells in UV (5 J/m2)
AMEM + 5%
FBS
Effects
Pb acetate alone did not induce single strand breaks. UV did induce
strand breaks. Co-exposure of Pb and UV cause DNA strand breaks to
persist longer suggesting an inhibition of repair.
Reference
Hartwig et al.
(1990)
Abbreviations
Medium and Components
AMEM—Alpha Minimal Essential Medium;
FBS—Fetal Bovine Serum
O
to
-------
>
X
Table AX5-6.17. Genotoxic/Carcinogenic Effects of Lead—Epigenetic Effects and Mixture
Interactions—DNA Repair—Animal
Compound
Pb acetate
Assay (Concentration and
Exposure Time)
Cytotoxicity (0.5-5 uM for 24 h)
Mutagenesis— HPRT (0.5-5 uM
for 44h)
Cell Type
and Culture
Medium Co-exposure
V79 in UV (5 J/m2)
AMEM + 10%
FBS
Effects
Pb acetate ( 3 and 5 uM) increased UV-induced increased cytotoxicity
with no dose response (plateau). There were no statistical analyses of
these data.
Reference
Hartwigetal. (1990)
SCE (1-10 uM for 26 h+)
Pb acetate (0.5—5 uM) increased UV mutagenicity though with no
dose response (plateau). There were no statistical analyses of these
data
Pb acetate (1-10 uM) increased UV-induced SCE. Significant at
p < 0.01. Only 25 cells per treatment analyzed.
Pb acetate
Mutagenesis — gpt
(0.5-1700 mM for 24 h)
DNA strand breaks as
supercoiled relaxation
(1000mMfor24h)
G12-CHV79
cells with 1
copy gpt gene
in Ham's F12
+ 5% FBS
UV (2 J/m2), or MNNG
(0.5 ug/L)
Pb acetate was co-mutagenic with UV and MNNG increasing
frequency 2-fold.
Pb acetate does not increase strand breaks induced by UV.
Roy and Rossman
(1992)
Abbreviations
G12-CHV79 are derived from V79;
V79 are a Chinese Hamster Lung Cell Line;
Medium and Components
AMEM—Alpha Minimal Essential Medium;
FBS—Fetal Bovine Serum
-------
Table AX5-6.18. Genotoxic/Carcinogenic Effects of Lead—Mitogenesis—Animal
Compound
Exposure Regimen
Species
Co-exposure
Effects
Reference
>
X
Pb acetate Administered Pb acetate (12.5 mg/kg) i.p. Male B6 Mice
Animals studied 24 h after injection.
Pb nitrate Liver initiation induced by the resistant hepatocyte Male Wistar
model Rats—4 per group
Initiation followed by i.v. injection of Pb nitrate
(100 uM/kg ) or partial hepatectomy
Studied DNA synthesis (30 h after injection) and
preneoplastic nodule formation
(5 wks after injection)
Pb nitrate Liver initiation induced by the resistant hepatocyte Male Wistar
model (diethylnitrosamine followed by 2- Rats—4 per group
acetylaminofluorene plus carbon tetrachloride)
Initiation followed by i.v. injection of 4 doses of Pb
nitrate (100 uM/kg ) given once every 20 days or
partial hepatectomy, ethylene dibromide, or
nafenopine
Animal were evaluated for preneoplastic foci at 75 or
155 days after initiation.
None Pb acetate induced TNF-alpha in glial and Cheng et al. (2002)
neuronal cells in the cerebral cortex and
subcortical white matter and on Purkinje cells in
the cerebellum, but did not induced apoptosis in
these areas
Partial Hepatectomy Pb nitrate stimulated DNA synthesis and liver cell Columbano et al.
proliferation (1987)
Pb nitrate did not induce preneoplastic nodule.
Partial hepatectomy did.
Diethylnitrosamine Pb nitrate, partial hepatectomy, ethylene Columbano et al.
dibromide, or nafenopine all stimulated DNA (1990)
synthesis and liver cell proliferation
Pb nitrate, ethylene dibromide, or nafenopine did
not induce preneoplastic nodule. Partial
hepatectomy did.
Pb nitrate Liver initiation induced by the orotic acid model
(diethylnitrosamine plus orotic acid)
Initiation followed by i.v. injection of Pb nitrate
(100 uM/kg) or partial hepatectomy, or by gavage:
ethylene dibromide, or cyproterone
DNA synthesis was examined at various time
intervals (24 h—5 days) after injection.
Male Wistar Diethylnitrosamine Pb nitrate, partial hepatectomy, ethylene
Rats—4 per group dibromide, or cyproterone all stimulated DNA
synthesis within 30 min.
Pb nitrate induced DNA synthesis for 5 days.
Coni et al. (1992)
-------
Table AX5-6.18 (cont'd). Genotoxic/Carcinogenic Effects of Lead—Mitogenesis—Animal
Compound
Exposure Regimen
Species
Co-exposure
Effects
Reference
>
X
Pb nitrate Liver initiation induced by the resistant hepatocyte
model (diethylnitrosamine followed by 2-
acetylaminofluorene plus carbon tetrachloride) or the
phenobarbital model (diethylnitrosamine plus orotic
acid), or the orotic acid model (diethylnitrosamine
plus orotic acid)
Initiation followed by i.v. injection of Pb nitrate
(100 uM/kg ) or partial hepatectomy, or carbon
tetrachloride by gavage
Animals were studied 6 wks after initiation.
Pb nitrate Liver initiation induced by the resistant hepatocyte
model (diethylnitrosamine followed by
2-acetylaminofluorene plus carbon tetrachloride)
Initiation followed by i.v. injection of Pb nitrate
(100 uM/kg ) or partial hepatectomy, or by gavage:
ethylene dibromide, or cyproterone, or nafenopine
Also tried either 1 or 2 additional i.v. injections of Pb
over 3-day intervals.
Animals were studied at various intervals (1-6 days)
after injection
Pb nitrate Administered as i.v. injection of Pb nitrate
(100 uM/kg ) or partial hepatectomy, or by gavage:
carbon tetrachloride, or ethylene dibromide, or
cyproterone, or nafenopine
Animals were studied at various time intervals
(0.25-24 h) after injection.
Pb nitrate Administered as i.v. injection of Pb nitrate
(100 uM/kg) or partial hepatectomy, or nafenopine by
gavage.
Animals were studied at various time intervals
(24-96 h) after injection.
Pb nitrate Administered as i.v. injection of Pb nitrate
(10 uM/100 g)
Studies for apoptosis at 12, 24, 36, 48, 72, 96, 120,
168, 336 h after injection
Male Wistar
rats—4 per group
Male Wistar
rats—4 per group
Male Wistar
rats—4 per group
Male Wistar
rats—4 per group,
8 wks old
Male Wistar
rats—4 rats per
group
Partial
Hepatectomy,
carbon tetrachloride
Diethylnitrosamine,
2-AAF
Partial
Hepatectomy,
carbon tetrachloride
None
None
Pb nitrate, partial hepatectomy, carbon
tetrachloride all stimulated DNA synthesis and
liver cell proliferation
Pb nitrate, did not induce preneoplastic nodules.
Partial hepatectomy and carbon tetrachloride did.
Ledda-Columbano
etal. (1992)
Coni et al. (1993)
Coni et al. (1993)
This study aimed to determine if mitogens induce
nodules at different time points.
Pb nitrate, ethylene dibromide, cyproterone, or
nafenopine did not induce preneoplastic nodules
at all. Partial hepatectomy did within 3 days.
Multiple injections of Pb nitrate did not induce
preneoplastic lesions.
Pb nitrate, ethylene dibromide, cyproterone, or
nafenopine induced c-jun and c-myc but did not
induce c-fos.
Partial hepatectomy and carbon tetrachloride
induced c-jun, c-fos, and c-myc.
Pb nitrate induced a high incidence of polyploidy
and binucleated cells. These changes were
irreversible after 2 wks. Many of these cells were
the newly synthesized cells.
Partial hepatectomy and carbon tetrachloride
induced tetraploid and octaploid mononucleated
cells.
Liver weight increased until day 5 then returned to Nakajima et al.
control levels. (1995)
DNA synthesis peaked at 36 h
Apoptosis peaked at day 4 and then decreased
gradually.
Melchiorri et al.
(1993)
-------
Table AX5-6.18 (cont'd). Genotoxic/Carcinogenic Effects of Lead—Mitogenesis—Animal
>
X
Compound
Pb nitrate
Pb nitrate
Exposure Regimen
Administered as i.v. injection of Pb nitrate
(100 uM/kg) or TNF-alpha.
Animals were studied at various time intervals
(12-48 h) after injection.
Administered after diethylnitrosamine (200 mg/kg
given i.p) as i.v. injection of Pb nitrate (100 uM/kg )
Species
Male Wistar
Rats — 4 per
group, 5-6 wks
old
Male Wistar
Rats — 4 per group
Co-exposure
None
Carbon
tetrachloride
Effects
Pb nitrate and TNF-alpha induced similar
proliferative responses.
Pb nitrate induced apoptosis affects both newly
synthesized cells and non-replicative cells.
Reference
Shinozuka et al.
(1996)
Columbano et al.
(1996)
or instead carbon tetrachloride by gavage
Animals were studied at various time intervals
(3-21 days) after injection.
Pb nitrate Administered as i.v. injection of Pb nitrate
(100 uM/kg ) or partial hepatectomy, or by gavage:
carbon tetrachloride, or cyproterone, or nafenopine
Animals were studied at various time intervals
(0.5-24 h) after injection.
Male Wistar
Rats—8 wks old
Partial
Hepatectomy,
ethylene
dibromide,
nafenopine, or
cyproterone
Pb nitrate decreased the number and had no effect
on the size of placental glutathione-S-transferase
lesions. Carbon tetrachloride substantially
increased these lesions both in number and in size.
Pb nitrate induced NF-kB, TNF-alpha and iNOS,
but not AP-1.
Carbon tetrachloride induced and activated NF-kB,
TNF-alpha iNOS, and AP-1.
Nafenopine and cyproteone did not induce or
activate NF-kB,TNF-alpha iNOS, or AP-1.
Menegazzi et al.
(1997)
-------
Table AX5-6.19. Genotoxic/Carcinogenic Effects of Lead—Mitogenesis Human and Animal Cell Culture Studies
Assay (Concentration and Cell Type and
Compound Exposure Time) Culture Medium Co-exposure
Effects
Reference
>
X
Pb acetate
Pb acetate
Pb acetate
Pb acetate
Pb acetate
Pb acetate
Cell Proliferation (0.1-100 uM for H4-II-C3—human
2-6 days) hepatoma cells in DMEM
DNA synthesis (1-100 uM for + 2'5°/0 FCS
72 h)
Tyrosine aminotransferase
expression and activity (0.3-10 uM
for 24- 48 h)
Cell proliferation (10 uM-lmM for REL cells—Rat Epithelial
24h-7days) cells in Ham's F10
medium + 10%FBS
Cell growth (0.01-10 uM for
12-72 h)
Expression of genes in cytokine
pathways (0.01-10 uM for 24 h)
Cell proliferation (0.078-320 uM
for 48 h)
Apoptosis (1.25-80 uM)
Cell cycle analysis
DNA synthesis (1-50 uM for 24 h)
Expression of genes in mitogen
activated pathways (1-50 uM for
5 min-4 h)
Cell proliferation (1 uM for 24 h)
Cell differentiation
(1 uM for 48 h)
PKC activation (1 uM for 24 h)
U-373MG—human
glioma cell line in DMEM
+ 10 or 20% FBS
Rat-1 fibroblasts in
EMEM +10% FBS
1321Nl-human
astrocytoma cells in
DMEM + 0.1%BSA
Primary oligodendrocyte
progenitor cells-in
DMEM + 1% FBS
Dexamethasone Pb acetate inhibited cell growth in a time- and dose-
(0.1 uM for 16 h) dependent manner.
Pb acetate inhibited DNA synthesis in a dose-dependent
manner.
Pb acetate alone did not inhibit tyrosine aminotransferase.
Pb acetate inhibited glucocorticoid-induction of tyrosine
aminotransferase in a time- and dose-dependent manner.
None Pb acetate inhibited cell growth at all concentrations for
24 h-7 days.
Pb acetate did not affect gap junction capacity, which is
often inhibited by tumor promoters.
None Pb acetate did not inhibit or enhance cell growth.
Pb acetate enhanced the expression of TNF-alpha, but
decreased interleukin-1 beta, interleukin-6, gamma-
aminobutyric acid transaminase, and glutamine synthetase
under 10% FBS.
Pb acetate further enhanced the expression of TNF-alpha
under 20% serum, but had no effect at all on expression of
the other genes.
None Pb acetate inhibited cell growth at 0.635-320 uM.
Pb acetate induced apoptosis from 2.5-10 uM.
Pb acetate caused GS/M and S-phase arrest.
None Pb acetate induced DNA synthesis.
Pb acetate induced activation of MAPK, ERK1. ERK2,
MEK1 , MEK2, PKC, andpgO^.
Pb acetate did not activate PI3K or p70s*.
None Pb acetate inhibited basal and growth factor stimulated
growth.
Pb acetate inhibited cell differentiation in a PHC-dependent
manner.
Pb acetate redistributes PKC from the cytosol to the
membrane, but did not increase PKC activity.
Heiman and
Tonner(1995)
Apostoli et al.
(2000)
Liu et al. (2000)
lavicoli et al.,
(2001)
Lu et al. (2002)
Deng and Poretz
(2002)
-------
Table AX5-6.19 (cont'd). Genotoxic/Carcinogenic Effects of Lead—Mitogenesis Human and Animal Cell Culture Studies
Assay (Concentration and
Compound Exposure Time)
Pb acetate Expression of TNF-alpha
(0.1-10nMfor24h)
Pb chloride Cell proliferation
(10 uM-lmM for 24-48 h)
Pb oxide Cell proliferation
(10 uM-lmM for 24 h-7 days)
Q Pb sulfate Cell proliferation
£> (10 uM-lmM for 24-48 h)
i
O
oo
Pb chromate Apoptosis (350 uM for 24 h)
Pb chromate Apoptosis (0.4-2 ug/cm2 for 24 h)
Pb chromate Growth Curve (0.5-5 ug/cm2 24 h)
Pb glutamate Growth Curve
(250-1,000 uM for 24 h)
Pb glutamate Mitotic Index
(250-2,000 uM for 24 h)
Growth Curve
(250-2,000 uM for 24 h)
Cell cycle Analysis
(250-2,000 uM for 24 h)
Cell Type and
Culture Medium
U-373MG— human
glioma cell line in
DMEM + 20% FBS
REL cells — Rat Epithelial
cells in Ham's F10
medium + 10% FBS
REL cells— Rat Epithelial
cells in Ham's F10
medium + 10% FBS
REL cells— Rat Epithelial
cells in Ham's F10
medium + 10% FBS
Chinese Hamster Ovary
AA8 cells in AMEM +
10% FBS
Primary Human Small
Airway Cells in Clonetics
growth medium
WTHBF-6 — human lung
cells with hTERT in
DMEM/F12 + 10% CCS
WTHBF-6 — human lung
cells with hTERT in
DMEM/F12 + 10% CCS
WTHBF-6 — human lung
cells with hTERT in
DMEM/F12 + 10% CCS
Co-exposure Effects
None Pb acetate did not induce apoptosis.
Pb acetate increased the expression of TNF-alpha in a dose-
dependent manner.
TNF-alpha was not involved in Pb-induced apoptosis.
None Pb chloride inhibited cell growth at all concentrations for
24^18 h.
Pb chloride did not affect gap junction capacity, which is
often inhibited by tumor promoters.
None Pb oxide inhibited cell growth at all concentrations for
24 h-7 days.
Pb oxide did not affect gap junction capacity, which is often
inhibited by tumor promoters.
None Pb sulfate inhibited cell growth at all concentrations for 24—
48 h.
Pb sulfate did not affect gap junction capacity, which is
often inhibited by tumor promoters.
None Pb chromate induced apoptosis.
This study was focused on chromate.
None Pb chromate induced apoptosis in a concentration-
dependent manner.
None Pb chromate inhibited cell growth.
None Pb glutamate had no effect on growth.
None Pb glutamate induced a concentration-dependent increase in
intracellular Pb ions.
Pb glutamate increased the mitotic index, but either had no
effect or inhibited growth and induced mitotic arrest.
Reference
Cheng et al.
(2002)
Apostoli et al.
(2000)
Apostoli et al.
(2000)
Apostoli et al.
(2000)
Blankenship
etal. (1997)
Singh et al.
(1999)
Holmes et al.
(2005)
Wise et al. (2005)
Wise et al. (2005)
-------
Table AX5-6.19 (cont'd). Genotoxic/Carcinogenic Effects of Lead—Mitogenesis Human and Animal Cell Culture Studies
Compound
Pb nitrate
Pb nitrate
Pb nitrate
Assay (Concentration and
Exposure Time)
Mitotic Index
(3-30 uM for 2h +16 h recovery)
Mitotic Index
(0.05-1 uM for 3-12 h)
Apoptosis (15-240 uM for 3 h)
Cell Type and
Culture Medium
CHO cells in EMEM +
10% FBS
CHO AA8 in DMEM
+10%NCS
Rat Alveolar
Macrophages in DMEM
+ 10% FBS
Co-exposure
None
Crown ethers to modify
effect through chelation
and uptake
None
Effects
Lower concentrations (1 and 3 uM) of Pb nitrate
significantly increased the mitotic index. Higher
concentrations (10 and 30 uM) had no effect.
Pb nitrate dramatically reduced the mitotic index at 1 uM
though this was not statistically analyzed. There was no
effect on mitotic index at lower concentrations. Crown
ethers had no modifying effect.
Pb nitrate induced apoptosis in a dose-dependent manner.
Reference
Lin et al. (1994)
Cai and Arenaz
(1998)
Shabani and
Rabbani (2000)
>
X
Abbreviations
G12-CHV79 are derived from V79;
V79 are a Chinese Hamster Lung Cell Line;
hTERT is the catalytic subunit of human telomerase
Medium and Components
AMEM—Alpha Minimal Essential Medium;
DMEM—Dulbecco's Minimal Essential Medium;
DMEM/F12—Dulbecco's Minimal Essential Medium/Ham's F12;
EMEM—Eagle's Minimal Essential Medium;
BSA—Bovine Serum Albumin
CCS—Cosmic Calf Serum
FBS—Fetal Bovine Serum
FCS—Fetal Calf Serum
NCS—Newborn Calf Serum
Differences between the serum types are unclear as insufficient details are provided by authors to distinguish.
-------
Table AX5-6.20. Genotoxic/Carcinogenic Effects of Lead—Mitogenesis Other
X
Compound
Pb acetate
Pb acetate
Pb acetate
Pb chloride
Pb chloride
Assay (Concentration and
Exposure Time)
Production of reactive oxygen
species (1 mM for 180 min)
Glutathione levels
(1 mM for 0-1 80 min)
Catalase Activity
(500-2,000 uM for 24 h)
Thiol Levels
(100nMfor30min^th)
Oxidative Metabolism
(0. 1-100 uM for 20 h)
Phagocytosis (0.1-100 uM for
20 h)
Oxidative Enzyme Levels
(0.1-1 uMfor Ih)
Cell Type and
Culture Medium
SH-SY5Y— Human
neuroblastoma cells in
DMEM + 7% FCS
Human Foreskin
Fibroblasts (Chinese) in
DMEM +10% FCS
HeLa in HEPES/glucose
buffer
Macrophages from NMRI
mice in EMEM (serum
not given)
AS52-CHO-gpt, lackhprt
in HBSS followed by
Ham'sF12 + 5%FBS
Co-exposure
Glutamate (1 mM)
or PKC inhibitor
(IjiM)
3-aminotriazole
(3-AT) (80 mM to
inhibit catalase)
Buthionine
sulfoximine
(BSO) to deplete
cells of thiols
Zymosan and
latex particles as
substrates for
phagocytosis
Allopurinol
(50 uM) to inhibit
xanthine oxidase
Effects
Pb acetate alone did not produce reactive oxygen species. Glutamate
alone did.
Pb acetate plus glutamate increase glutamate induced increases in
reactive oxygen species.
Pb acetate alone did not deplete glutathione. Glutamate alone did.
Pb acetate plus glutamate decreased glumate-induced decrease in
glutathione.
Pb acetate had no effect on catalase activity.
Pb acetate only lowered thiols marginally
Pb inhibited oxidative metabolism.
Pb inhibited phagocytosis, but only significantly at the highest dose.
Pb chloride at low concentrations produced H2O2 at 1 h and not at
24 h. Pb chloride at high concentrations produced no change at 1 h
and increased H2O2 at 24 h. Allopurinol inhibited H2O2 formation at
high Pb concentrations.
Pb chloride had no effect on catalase, glutathione peroxidase,
glutathione reductase. Pb chloride inhibited glutathione-S-
transferase, CuZn-superoxide dismutase, and xanthine oxidase.
Reference
Naarala et al.
(1995)
Hwua and
Yang (1998)
Snyder and
Lachmann
(1989)
Hilbertz et al.
(1986)
Ariza et al.
(1998)
Abbreviations
AS 52 are derived from CHO;
CHO are a Chinese Hamster Ovary Cell Line;
Medium and Components
DMEM—Dulbecco's Minimal Essential Medium;
EMEM—Eagle's Minimal Essential Medium;
HBSS—Hank's Balanced Salt Solution
FBS—Fetal Bovine Serum
FCS—Fetal Calf Serum
Differences between the serum types are unclear as insufficient details are provided by authors to distinguish.
-------
ANNEX TABLES AX5-7
AX5-111
-------
Table AX5-7.1. Light Microscopic, Ultrastructural, and Functional Changes
Author
Animal Species
Lead Dosage
Blood Lead
Findings
>
X
Khalil-Manesh
etal. (1992a)
Khalil-Manesh
etal. (1992b)
Khalil-Manesh
etal. (1993a)
Sprague-Dawley 0.5% Pb acetate in drinking water
rat for 12 mo
Sprague-Dawley
rat
0.5% Pb discontinued after 6 mo
0.01% Pb discontinued after 6 mo
DMSA 0.5% used in 1/2
Sprague-Dawley 0.01% Pb acetate for 12 mo
rat
Max 125.4 ug/dL
Mean 55 ug/dL
Hi Pb @12 mo
Disc 30.4 ug/dL
Disc + DMSA 19.1 ug/dL
Ctrl 3.1 ng/dL
Lo Pb@12mo
Disc 6.9 ug/dL
DMSA5.5 ug/dL
Max 29.4 ug/dL
Range 9-34 ug/dL
Hyperfiltration at 3 mo. Decreased filtration at 12 mo.
NAG and GST elevated.
Nuclear inclusion bodies at all times.
Tubulointerstitial scarring from 6 mo.
No arterial or arteriolar pathology.
High Pb:
Nuclear inclusion bodies prominent.
Tubulointerstitial disease severe but less than 12 mo
continuous DMSA caused reduction in nuclear inclusion
bodies and tubuloint decrease, and an increase in GFR.
LowPb:
Neg pathology and increase in GFR with DMSA
GFR increased at 1 and 3 mo.
NAG increased but GST normal.
Pathology neg except at 12 mo—mild tubular atrophy and
interstitial fibrosis seen.
Sanchez-
Fructuoso et al.
(2002a)
Sanchez-
Fructuoso et al.
(2002b)
Papaioannou et al.
(1998)
Wistar rat 500 ppm (0.05%) Pb acetate for
2 mo, then EDTA
Wistar rat 500 ppm (0.05%) Pb acetate for
2 mo, then EDTA
Dogs 12 mg Pb acetate i.p. x 10
Max 52.9 ug/dL
Day 90: 33.2
Day 137: 22.8
Ctrl: 5.90 ug/dL
Max 52.9 ug/dL
Day 90: 33.2
Day 137: 22.8
Ctrl: 5.90 ug/dL
Rats given Pb to day 90, then treated with EDTA or untreated
today 137.
Marked decrease in kidney, liver, and brain Pb with EDTA but
no change in femur Pb
Hypertrophy and vacuolization of medium and small arteries,
mucoid edema and muscular hypertrophy of arterioles, include
bodies and fibrosis.
EDTA slowed progression.
Pb includes bodies intracytoplasmically in mesothelial and
giant cells of peritoneum and in interstitial connective tissue
cells of kidney. None in prox tubules of kidney.
-------
Table AX5-7.1 (cont'd). Light Microscopic, Ultrastructural, and Functional Changes
X
Author
Vyskocil et al.
(1989)
Vyskocil et al.
(1995)
Vyskocil and
Cizkova(1996)
Sanchez et al.
(2001)
Herak-
Kramberger et al.
(2001)
Fujiwaraet al.
(1995),
Kajietal. (1995b)
Animal Species Lead Dosage
Wistar rat 0.5%, 1%, and 2% Pb acetate for
2-3 mo
Wistar rat 1 % or 0 . 1 % Pb acetate for 1-4 mo
Wistar rats Unleaded petrol vapor (4mg/m3)
8 hrs/day for 60 days
Sprague-Dawley 0.06% Pb acetate for 4 mo
rat
Rat brush border 500 uM Pb
membranes
B ovine cultured 0.5-10uMPb nitrate
vascular smooth
muscle and
endothelial cells
Blood Lead
0.5%-105 ug/dL
1%-196 ug/dL
2%-320 ug/dL
1%-173 ug/dL
0.1%-37.6 ug/dL
—
13.9 ug/dL vs. <0. 5 ug/dL
in ctrl
—
—
Findings
0.5% — no morphologic or functional changes.
1% — Incr in P-2 microglobulin excretion.
2% — Incr in P2micr, glucose, protein, lysozyme, and LDH.
Hyperplasia and include bodies of prox tubules seen in both
I%and2%.
1% caused increase in P-2 microglobulin excretion and injury
to proximal tubule.
0.1% caused no changes.
B-2 microglobulin excretion increased at 60 days.
Decrease in expression of laminin-1 and increase in expression
of fibronectin in kidneys.
58% loss of sealed brush border membrane vesicles. Lower
loss of sealed basolateral membrane vesicles.
Stimulated proliferation in smooth muscle cells. Reduced
proliferation in endothelial cells No leakage of LDH.
-------
Table AX5-7.2. Lead and Free Radicals
>
X
Author
Pereira et al.
(1992)
Somashekaraiah
etal. (1992)
Bondy and Guo
(1996)
Blazka et al.
(1994)
Animal Species
Rats
Chick embryos
Sprague-Dawley
rat cerebral
synapto somes
Mouse brain
micro vascular
endothelial cell
culture
Lead Dosage Blood Lead
ALA-treated (40 mg/kg every
2 days for 15 days)
1 .25 and 2.5 momol/kg of Pb acetate
0.5 mM Pb acetate
10, 100, and 1,000 nM Pb acetate
Findings
Fatigued earlier than controls.
Increase of CuZn SOD in brain, muscle and liver.
Lipoperoxides maximal at 9 hrs and returned to normal at
72 hrs.
GSH depleted. GST, SOD and catalase increased in liver,
brain and heart at 72 hrs.
Generation of ROS not increased by Pb alone but increased
when 50 uM iron sulfate added.
Constitutive production of nitrite, but not inducible, decreased
by Pb. Extracellular calcium abolishes this effect.
Quinn and Harris Rat cerebellum
(1995) homogenates
Ercal et al. (1996) C57BL/6 mice
17-80 nMPb nitrate
1300 ppm Pb acetate for 5 wks,
Nac, 5.5 mmol/kg, or DMSA,
1 mmol/kg, given in 6th week.
36.5 ug/dL in Pb-treated;
13.7 ug/dL in Pb +
DMSA-treated
Constitutive NOS activity inhibited 50% by 17 nM Pb and
100% by 80 nM Pb. Reversed by increasing Ca concentration.
Liver and brain GSH depleted by Pb and MDA increased.
Both were restored by either DMSA or NAC. However,
DMSA reduced blood, liver, and brain Pb levels while NAC
did not.
Vaziri and co-
workers (1997-
2004)
Farmand et al.
(2005)
Gurer et al.
(1999)
Sprague-Dawley
rats
Sprague-Dawley
rats
See Section 5.5 for details
100 ppm Pb acetate for 3 mo
Variable
Fischer 344 rats 1100 ppm Pb acetate for 5 wks,
Captopril for 6th wk
24.6ug/dL in Pb-treated.
23.8 ug/dL in Pb +
Captopril-treated
See Section 5.5 for details.
CuZnSOD activity increased in kidney. CuZnSOD activity
increased in aorta whereas protein abundance unchanged.
Guanylate cyclase protein abundance in aorta decreased.
MDA in liver, brain, and kidney increased by Pb. GSH
decreased. Captopril reversed these findings.
-------
Table AX5-7.2 (cont'd). Lead and Free Radicals
Author
Animal Species
Lead Dosage
Blood Lead
Findings
Acharya and
Acharya(1997)
Upasani et al.
(2001)
Pande et al.
(2001)
Swiss mice 200 mg/kg Pb acetate i.p. x 1
Rats 100 ppm Pb acetate for 30 days,
Groups given vit C, vit E, or algae
Wistar rats Pb nitrate 50 mg/kg i.p. x 5
Pb + DMSA,MiADMSA,NAC,
DMSA + NACTJMSA +
MiADMSA
MDA-TBA increased x 4 in liver, brain, kidney, and testis by
end of 1 st wk and persisted for 4 wks.
MDA, conj dienes, and H2O2 increased in liver, lung, and
kidney by Pb. Treatment with vit C, vit E, or Blue Green algae
reversed these findings.
DMSA most effective in blocking inhib of ALAD, elev of
ZPP, and inhib of GSH. Combined DMSA+NAC most
effective when given during or post-exposure.
>
X
Pande and Flora Wistar rats
(2002)
2000 ppm Pb acetate x 4 wks,
DMSA,MiADMSA, DMSA +
LA,MiADMSA + LA x 5 days
Pb caused decrease in ALAD, GSH, and increase ZPP. Lipoic
acid (LA) did not chelate Pb in contrast to DMSA, but both
agents increased ALAD and GSH.
Flora et al. (2003) Wistar rats
Saxena and Flora Wistar rats
(2004)
1000 ppm Pb acetate x 3 mo,
DMSA or MiADMSA + vit C or
vit E x 5 days
2000 ppm Pb acetate x 6 wks,
CaNa2EDTA + DMPS or
MiADMSA x 5 days
13.3 |ig/dL
PbRx
3 |ig/dL DMSA Rx
-------
Table AX5-7.2 (cont'd). Lead and Free Radicals
Author
Animal Species
Lead Dosage
Blood Lead
Findings
Sivaprasad et al.
(2002)
Wistar rats
>
X
Senapati et al. Rats
(2000)
Patra et al. (2001) IVRI 2CQ rats
McGowan and Chicks
Donaldson (1987)
2000 ppm Pb acetate x 5 wks
LA and DMSA during 6th week.
1% sol of 5 mg/kg
Pb acetate x 43 days
Thiamine 25 mg/kg
1 mg/kg Pb acetate for 4 wks
Vit E, vit C or methionine in 5th wk.
VitE + EDTA.
2000 ppm Pb acetate x 3 wks
6.8 ng/dL Pb-Rx
6.3 ng/dL
Pb, vit E +EDTA
Pb caused red in kidney GGT and NAG, decline in GSH,
catalase, SOD, GPx and Glut reductase, and increased MDA.
Lipoic acid
+DMSA restored these changes.
Thiamine reduced Pb content and MDA levels of both liver
and kidney and improved pathology.
Pb in liver, kidney and brain reduced by vit E + EDTA
treatment. MDA increased by Pb in all 3 organs but decreased
by vit E + EDTA.
GSH, non-protein SH, lysine and methionine increased in liver
and non-prot SH, glycine, cysteine and cystathionine in
kidney. Cysteine reduced in plasma.
-------
Table AX5-7.3. Chelation with DMSA
X
Author
Cory-Slechta
(1988)
Pappas et al.
(1995)
Animal Species
Rats
Sprague-Dawley
rats
Lead Dosage
50 ppm Pb acetate for 3^ mo
550-1 100 ppm Pb acetate for
35 days
Blood Lead
20 ng/dL-Pb
1 |ig/dL-Pb+25 mg/kg
DMSA
52 ng/dL @ 550 ppm Pb
65|ig/dL@1100ppmPb
Findings
DMSA 25-50 mg/kg i.p. for 1-5 days mobilized Pb from
blood, brain, kidney and liver, but not femur.
DMSA @16-240 mg/kg/d p.o. for 21 days given with and
without concurrent Pb exposure. Rats showed dose-related
reduction in Pb content of blood, brain, femur, kidney, and
liver with or without concur Pb.
Smith and Flegal Wistar rats
(1992)
Varnai et al.
(2001)
Wistar rats
(suckling)
206Pb 210 ng/mL for 1.5 days
DMSA 20 mg/kg i.p.
2 mg/kg/d for 8 days
DMSA 0.5 mmol/kg 6x/d on dl-3
and 6-8
5.1 ng/g-ctrl
3.0ng/g-DMSA
Rats on low Pb diet given DMSA decreased soft tissue but not
skeletal Pb. Pb redistributed to skeleton.
DMSA reduced Pb concentration in carcass, liver, kidneys, and
brain by -50%.
-------
Table AX5-7.4. Effect of Chelator Combinations
Author
Animal Species
Lead Dosage
Blood Lead
Findings
Flora et al.
(2004)
Jones et al.
(1994)
Wistar rats 1000 ppm Pb acetate for 4 mo
Mice 10 i.p. injections of Pb acetate,
5.0mg/kg
46 ng/dL-Pb
12.8 ng/dL-combined Rx
5 days Rx with DMSA. CaNa2EDTA, or DMSA +
CaNa2EDTA. Comb Rx resulted in increased ALAD and
decreased Pb in blood, liver, brain, and femur.
Mice Rx'ed with DMSA, CaNa2EDTA, ZnNa2EDTA, or
ZnNa3DTPA 1.0 mmol/kg/d 4-8 days. CaNa2EDTA most
effective in removing brain Pb; DMSA in removing kidney
and bone Pb.
>
X
oo
Kostial et al.
(1999)
Flora et al.
(2004)
Sivaprasad et al.
(2004)
Malvezzi et al.
(2001)
Tandon et al.
(1997)
Wistar rats 5 mg Pb/kg i.p. x 1
(suckling) Chel agents days 2 and 3
Wistar rats 1000 ppm Pb acetate x 2 mo
Wistar rats 2000 ppm Pb acetate x 5 wks
Wistar rats 750 ppm Pb acetate x 70 days
DMSA, arginine, DMSA + arg or
H2O x 30 days
Rats 1000 ppm Pb acetate for 7 wks.
Dithiocarbamate x 4 days
67.8ng/dLtoll.2|ig/dL
in H2O Rx'ed to 6.1
|ig/dL in DMSA + arg
105.3ng/dLinPb
86 |ig/dL in
dithiocarbamate.
EDTA, DMSA, racemic DMSA, EDTA + DMSA, EDTA +
rac DMSA given. EDTA reduced Zn in carcass and liver; rac
DMSA reduced Zn in kidneys. DMSA reduced Pb w/o
affecting Zn.
DMSA, taurine or DMSA + taurine given for 5 days. Both
taurine and DMSA restored GSH. Comb of DMSA + taurine
increased RBC SOD and decreased TEARS, while most
effectively depleting blood, liver, and brain Pb.
DMSA, lipoic acid or combination given during 6th week.
Renal enzymes, kidney Pb and renal ALAD restored by
combined Rx.
Pb increased BP and Pb levels in blood, liver, femur, kidney,
and aorta. DMSA + L-arginine most effective in lowering BP
and mobilizing Pb from tissues.
Two dithiocarbamates were compared: N-benzyl-D-glucamine
and N-(4-methoxybenzyl)-D-glucamine. They were only
partially effective in restoring ALAD, reducing liver and
kidney, but not brain Pb. They depleted Zn, Cu, and Ca.
-------
Table AX5-7.5. Effect of Other Metals on Lead
Author
Animal Species
Lead Dosage
Blood Lead
Findings
Maldonado-Vega Wistar rats
etal. (1996) (pregnant and
nonpregnant)
Olivi et al. (2002) MDCK canine
kidney cells
Bogden et al.
(1991)
Wistar rats
>
X
Skoczynska et al. Buffalo rats
(1994)
Othman and Albino rats
El-Missiry(1998)
Tandon et al.
(1992)
Albino rats
Flora et al. (1989) Albino rats
Flora et al. (1994) Wistar albino rats
100 ppm Pb acetate for 144-
158 days
0,1,100 ppm Pb for 31 wks
0.2% or 4.0% Ca diet
Pb 70 mg/kg 2x/wk for 7 wks Cd
20 mg/kg Ix/wk for 7 wks.
All intragastric.
Pb acetate 100 momol/kg I.M. x 1
Se 10 momol/kg I.M. 2 hrs before
Pb
Pb acetate 10 mg/kg/d p.o. x 6 wks.
EDTA or DTPA given for 5 days w/
or w/o Se
Pb acetate 10 mg/kg/d p.o. x 6 wks
Thiamine, Zn or thiamine + Zn x 6
wks
Pb acetate 10 mg/kg/d x 56 days
p.o. EDTA or EDTA + Zn x 5 days
p.o.
5.2 (ctrl) to 27.3 |ig/dL in
Pb-exposed
8 (non-preg)to 17 |ig/dL
in rats exposed only
during lactation
1.9 to 39.1 |ig/dLonlow
Ca diet and 2.0 to 53.3
|ig/dL on high Ca diet
5.1 to 29.6 |ig/dL in Pb-
exposed. 37.4 ng/dL in
Pb + Cd
17tol38|ig/dLafterPb
58 ng/dL after EDTA.
50 |ig/dL after EDTA + Se
6.2 to 120.9 |ig/dL after
Pb
44.1 ng/dL after thiamine
+ Zn
4.6 to 43.0 |ig/dLinPb.
22.5|ig/dLinEDTA
16.5ng/dLinEDTA +
Zn.
Pb administered to period before lactation (144 days) or to
mid-lactation (158 days).Pb in blood, kidney, liver, and bone
increased.
ALAD decreased and FEP incr. Lactation increased.
Blood Pb from 24.7 to 31.2 ng/dL and decreased bone Pb from
83.4 to 65.2 nmol/g.
In response to agonists ADP or bradykinin levels of
intracellular Ca increased 3-fold and 2-fold. Pb inhibited the
response.
At 100 ppm Pb high Ca diet produced higher BP and more
renal cancers than low Ca diet and higher levels of Pb in brain,
liver, bone, heart, and testis but lower levels in kidney. Serum
Ca on high Ca diet was 13.2 mg/dL.
Simultaneous Pb and Cd administration increased blood Pb but
decreased Pb in liver and kidneys as compared to Pb
administration alone.
Sodium selenite (Se is a well-known anti-oxidant) prevented
lipid peroxidation (TEARS) and reduction in GSH caused by
Pb. SOD and glut reductase also normalized.
Selenium had no additional benefit over chelators except for
higher ALAD and lower ZPP in blood, lower Pb in liver and
kidney.
Thiamine given as 25 mg/kg/d and Zn sulfate as 25 mg/kg/d.
ALAD restored by combined Rx. Liver and kidney Pb
affected to a minor degree but brain Pb not affected.
CaNa2 EDTA given as 0.3 mmol/kg/d i.p. and Zn sulfate as 10
or 50 mg/kg/d. ALAD partially restored after EDTA + Zn but
not after EDTA. EDTA reduced Pb in bone, kidney, and liver
but not in brain. Zn cone increased in blood, kidney, and brain
by 50 mg Zn dosage.
-------
Table AX5-7.5 (cont'd). Effect of Other Metals on Lead
Author
Animal Species
Lead Dosage
Blood Lead
Findings
Satija and Vij Albino rats Pb acetate 20 mg/kg/d i.p. x 3 days
(1995) Zn acetate 5 mg/kg/d i.p. x 3 days
Munoz et al. Wistar rats Pb acetate 60 ppm x 90 days,
(1993) Zn or methionine given
simultaneously
Tandon et al. Albino rats Pb acetate 10 mg/kg/d x 8 wks p.o.
(1997) Ethanol, Zn and lysine x 8 wks
<60 ug/dL-Pb
SAM reduces to average
of 7.3 ng/dL
1.8to47.2ng/dLwPb.
Decreased to 34.2 ug/dL
w Zn + lysine.
Pb caused a decrease in Hgb, ALAD, and uroporphyrinogen I
synthetase, partially restored by Zn. Total SH and non-protein
SH reduced by Pb, partially restored by Zn.
S-adenosyl-1-methionine (SAM) reduces blood Pb and
uroporphyrinogen I synthetase. RBC ALAD reduced by Pb
and 2 Rx. Liver ALAD decreased by Pb, increased by SAM.
Ethanol reduced blood but not liver GSH beyond Pb alone.
Zn + lysine partially restored ALAD, increased GSH, and
reduced Pb in kidney.
X
to
o
Hashmi et al.
(1989)
Tandon et al.
(1993)
Rats
Rats
Pb acetate 1000 ppm x 6 wks
Fe-deficient or norm diet
Pb acetate 400 momol/kg i.p. x 1
Fe deficient and Fe-sufficient diets
x 6 wk
Fe deficiency increased Pb in liver, kidney, spleen but
increased femur Pb at 3 wks and decreased femur Pb at 6 wks.
Pb induced hepatic metallothionein (MT). Fe deficient diet +
Pb restored kidney and intestinal MT from low levels caused
by Fe def Pb in liver and kidney enhanced by Fe def
Crowe and Wistar rat pups Pb acetate 2000 ppm x 15,21, and
Morgan (1996) 63 days
Fe def and Fe suff diets
Singh et al.
(1991)
Pregnant female
albino rats
Pb acetate 250-2000 ppm from
15-20 days of gestation.
At 63 days Fe def-
410 ug/dL
Fe suff rats 170 ug/dL
At 2000 ppm Pb, Fe def
220 ng/dL
Fe suff 160 ug/dL
Fe deficiency increased blood and kidney Pb but did not affect
brain or liver Pb. Fe levels in brain and kidney were
unaffected by Pb intoxication.
Fe def and Fe suff diets given to dams for 30 days. Fetuses
removed on 21 st day. At 2000 ppm, Pb in maternal blood,
placenta, and fetus higher in Fe def. Max pathol changes in
fetal kidney.
Shakoor et al. Albino rats Pb acetate 125 mg/kg x 90 days
(2000) Al chloride 50-100 mg/kg x 90 days
Plasma creat 1.88 mg/dL in Pb-Rx'ed; 1.34 mg/dL in
Pb + Al-Rx'ed Kidney Pb increased from 5.4 in Ctrl to
220 ug/g in Pb-Rx'ed, decreased to 98.9 ug/g in Pb + Al.
-------
ANNEX TABLES AX5-8
AX5-121
-------
Table AX5-8.1. Bone Growth in Lead-exposed Animals
Compound
Dose/Concentration
Duration Exposure
Route
Species
Effects
Blood Level
Reference
>
X
to
to
Pb acetate
41.7mgPb/l
83.3 mg Pb/1
166.6 mgPb/1
12 to 16 wks
Drinking water
Rat
Pb aerosol
77,249,orl546ug/m3
for 50 to 70 days
Inhalation
Rat
Pb level in bone of control animals
Wk 0 = 1.3 ± 0.83 ug Pb/g; Wk4 = 1.2 ± 0.99 ng Pb/g;
Wk 8 = 1.3 ± 1.08 ug Pb/g; Wk 12 = 0.8 ± 0.13 ug Pb/g;
Wkl6 = 1.3±0.95ugPb/g
Pb level in bone of animals receiving 41.7 mg Pb/1
Wk 0 = 1.0 ± 0.50 ng Pb/g; Wk4 = 5.9* ± 1.76 ng Pb/g;
Wk 8 = 2.9* ±1.15 ug Pb/g; Wk 12 = 6.2* ±1.01 ^g Pb/g;
Wk 16 = 6.0* ± 0.75 ug Pb/g
Pb level in bone of animals receiving 83.3 mg Pb/1
Wk 0 = 2.0 ± 0.97 ug Pb/g; Wk4 = 11.7* ± 3.56 ug Pb/g;
Wk 8 = 8.8* ± 3.37 ug Pb/g; Wk 12 = 14.3* ± 4.29 ng Pb/g
Pb level in bone of animals receiving 166.6 mg Pb/1
Wk 0 = 0.9 ± 0.23 ng Pb/g; Wk 4 = 17.0* ± 3.89 ug Pb/g;
Wk 8 = 35.7* ± 3.64 ug Pb/g; Wk 12 = 21.7* ± 5.11 ug Pb/g;
* significantly higher than control animals at corresponding time point
16.9 ± 6.6 ug Pb/g bone taken up in animals exposed to 77 ug/m3 for
70 days versus 0.2 ± 0.2 ug Pb/g in control animals;
15.9 ± 4.3 ug Pb/g bone in rats exposed to 249 ug/m3 for 50 days;
158 ± 21 ug Pb/g bone in rats exposed to 1546 ug/m3 for 50 days
Not given
Hac and Krechniak
(1996)
Control: 2.6 ug/dL
77 ug/m3: 11.5 ug/dL
249 ug/m3: 24.1 ng/dL
1546 ug/m3: 61.2ug/dL
Grobleretal. (1991)
Pb acetate
250 ppm or 1000 ppm
7 wks to females prior
to mating, continuing
through gestation and
lactation
Drinking water
Rat Offspring body weight was depressed relative to controls during
suckling (Day 11) and after weaning (Day 24) in high dose and
continuously Pb-exposed groups.
Continuous Pb exposure caused a greater decrease in offspring body
weight than Pb exposure only prior to or after parturition.
Decreased tail length growth suggested possible effects of Pb on tail
vertebral bone growth.
Dams prior to mating:
Control = 2.7 ± 0.6 ug/dL
250 ppm =39.9 ±3.5 ug/dL
1000 ppm = 73.5 ±9.3 ug/dL
Hamilton and
O'Flaherty(1994)
-------
Table AX5-8.1 (cont'd). Bone Growth in Lead-exposed Animals
Compound
Dose/Concentration
Duration Exposure
Route
Species
Effects
Blood Level
Reference
>
X
to
Pb acetate
Hi Pb animals 5000
ppm for 6 mo, reduced
to 1000 ppm;
Lo Pb animals 100 ppm
Drinking Water
Rat
Pb acetate
17 mg per kg of feed
50 days
In diet
Pb acetate
17 mg per kg of feed
50 days
In diet
Rat
Rat
In male rats exposed to 100 ppm Pb in drinking water and a low
calcium diet for up to one yr, bone density was significantly decreased
after 12 mo, while rats exposed to 5000 ppm Pb had significantly
decreased bone density after 3 mo. Pb content of femurs was
significantly elevated over the content of control rats at all time points
(1, 3, 6, 9, 12 mo). Trabecular bone from the low dose animals was
significantly decreased from 3 mo forward.
No differences in the length of the femurs, but the mean length of the
5th lumbar vertebra was significantly decreased. The mean length of
the femur growth plate cartilage was also significantly decreased in Pb-
exposed animals.
No differences in the length of the femurs, but the mean length of the
5th lumbar vertebra was significantly decreased. The mean length of
the femur growth plate cartilage was also significantly decreased in Pb-
exposed animals.
LowPb(|ig%):
1 mo
Control = 2 ± 1; Exp = 19 ± 10*
3 mo
Control = 2 ± 1; Exp = 29 ± 4*
6 mo
Control = 3 ± 1; Exp = 18 ± 2*
9 mo
Control = 1 ± 1; Exp = 17 ± 3*
12 mo
Control = 3 ± 1; Exp = 21 ± 3*
Hi Pb (ng%):
1 mo
Control = 3 ± 1; Exp = 45 ± 13*
3 mo
Control = 3 ± 1; Exp = 90 ± 15*
6 mo
Control = 4 ± 1; Exp = 126 ± 10*
9 mo
Control = 4 ± 1; Exp = 80 ± 39*
12 mo
Control = 3 ± 1; Exp = 59 ± 18*
*p< 0.001
Not given
Not given
Gruberetal. (1997)
Gonzalez-Riola et al.
(1997)
Escribano et al. (1997)
-------
Table AX5-8.1 (cont'd). Bone Growth in Lead-exposed Animals
Compound
Dose/Concentration
Duration Exposure
Route
Species
Effects
Blood Level
Reference
>
X
to
Pb acetate
0.6%
GD 5 to Adulthood
(various)
In drinking water
Pb acetate
0.05% to 0.45%
GD 5 through sacrifice
of pups at 21, 35, 55,
and 85 days
In drinking water
Pb nitrate
0.02% (125 ppm)
GD5 to 1 day before
sacrifice
In drinking water
Rat Early bone growth was significantly depressed in a dose-dependent
fashion in pups of Pb-exposed pups, with growth suppression in male
offspring considerably greater than females. Significant decreases in
plasma insulin-like growth factor and plasma sex steroids and
increased pituitary growth hormone were also observed.
Groups:
DDW = Dams and pups received distilled deionized water entire study
Ac/Ac = Dams and pups received acetic acid solution entire study
Preg = Dams received 0.6% Pb water from GD 5 to parturition
Lact = Dams received 0.6% Pb water during lactation only
P + L = Dams received 0.6% Pb water from GD 5 through lactation
Postnatal = Dams and pups received 0.6% Pb water from parturition
through adulthood
Pb/Pb = Dams and pups received 0.6% Pb water from GD 5 through
adulthood
Rat Early bone growth was significantly depressed in a dose-dependent
fashion in pups of all Pb-exposed groups, with growth suppression in
male offspring considerably greater than females. Significant
decreases in plasma insulin-like growth factor and plasma sex steroids
and increased pituitary growth hormone were also observed.
Between age 57 and 85 days growth rates were similar in control and
Pb-exposed pups, suggesting exposure at critical growth periods such
as puberty and gender may account for differences in growth reported
by various investigators.
Rat Exposure to 0.02% Pb nitrate (125 ppm Pb) did not significantly affect
growth, though males weighed significantly less than females.
Whole blood Pb (ug/dL) in
male/female offspring at age
Day 85:
DDW =5.5 ±2.0/6.8 ±1.5;
Ac/Ac = 1.9 ±0.2/1.4 ±0.3;
Preg = 9.1±0.7*/11.6±4.6*;
Lact =3.3 ±0.4/3.4 ±0.8;
P + L= 16.1 ± 2.3*710.4 ± 1.8*;
Postnatal = 226.0 ± 29.0*/292.0 ±
53.0*;
Pb/Pb = 316.0 ±53.0*/264.0 ±
21.0*
*p < 0.05 compared to Ac/Ac
group.
Offspring:
0.05% Pb = 49 ± 6 ug/dL; 0.15%
Pb = 126 ± 16 ug/dL; 0.45% Pb =
263 ± 28 ug/dL
Ronisetal. (1998a)
Ronisetal. (1998b)
Rat Pups
5 days old: 43.3 ±2.7 ug/dL
49 days old: 18.9 ± 0.7 ug/dL
(females: 19.94 ± 0.8 ug/dL;
males: 17.00 ±1.1 ug/dL)
Camoratto et al. (1993)
-------
Table AX5-8.1 (cont'd). Bone Growth in Lead-exposed Animals
Compound
Dose/Concentration
Duration Exposure
Route
Species
Effects
Blood Level
Reference
>
X
to
Pb acetate
0.15% or 0.45%
GD 4 until Day 55
In drinking water
Pb acetate
lOOOppm
22-26 days
In drinking water
Rat A dose-dependent decrease in load to failure in tibia from Pb-exposed
(0.15% and 0.45% Pb acetate in drinking water) male pups only.
Hormone treatments (L-dopa, testosterone or dihydrotestosterone in
males, or estradiol in females) failed to attenuate Pb deficits during the
pubertal period. Distraction osteogenesis experiments performed after
stabilization of endocrine parameters (at 100 days of age) found
decreased new endosteal bone formation and gap x-ray density in the
distraction gaps of Pb-exposed animals.
Rat Pb disrupted mineralization during growth in demineralized bone
matrix implanted subcutaneously into male rats. In the matrix that
contained 200 micrograms Pb/g of plaque tissue, alkaline phosphatase
activity and cartilage mineralization were absent, though calcium
deposition was enhanced. Separate experiments found enhanced
calcification and decreased alkaline phosphatase activity in rats
implanted with a control (no Pb) matrix and given 1000 ppm Pb in
drinking water for 26 days.
Offspring:
0.15%Pb = 67-192|ig/dL;
0.45% Pb= 120-388 ng/dL
Ronisetal. (2001)
Blood Pb(ngML)
Control:
Implantation Day 0 = 1.3 ± 0.6;
Day 8 = 2.2 ± 0.9; Day 12 = 2.1 ±
0.7.
Pb added to matrix:
Implantation Day 0 = 1.5 ± 0.8;
Day 8 = 5.7 ± 0.8a'b; Day 12 = 9.5
± 0.5a'b.
Pb in drinking water:
Implantation Day 0 = 129.8 ±
6.7a; Day 8 = 100.6 ± 6.8a'b
Day 12 = 96.4±5.3a'b
a Significant (p < 0.05) difference
from control.
b Significance (p < 0.05)
difference from corresponding
value at implantation (Day 0).
Hamilton and
O'Flaherty(1995)
Abbreviations
Mg—milligram
jig—microgram
ppm—parts per million
GD—gestational day
Pb—lead
g—gram
|ig%—microgram percent
1—liter
m3"—cubic meter
Exp—experimental group
wk—week
dL—deciliter
%—percent
-------
Table AX5-8.2. Regulation of Bone Cell Function in Animals—Systemic Effects of Lead
Compound
Dose/Concentration
Duration Exposure
Route
Species
Effects
Blood Level
Reference
>
X
to
Pb acetate
30 mg/kg
Single i.v. injection
Rat Groups of male rats were killed 0.5, 5,15, and 30 min and 1, 2, 6, and 12 h after the single
Pb injection. Serum calcium and phosphorus levels both initially increased after Pb
injection with serum phosphorus reaching a maximum value (13.5 mg%) after 30 min and
calcium (17 mg%) after 1 h. Calcium and phosphorus levels decreased after 1 h and
returned to baseline levels after 12 h.
Not given
Kato etal. (1977)
Pb acetate
0.82%
1 wk
In diet
Pb acetate
0.15% or 0.45%
GD 4 until Day 55
In drinking water
Rat Ingestion of 0.82% Pb in male rats fed either a low phosphorus or low calcium diet reduced
plasma levels of 1 ,25-(OH)2CC, while Pb had no effect in rats fed either a high calcium diet
or a normal phosphorus diet.
Effect of Pb on serum 1,25-fOH^CC levels in rats fed low P or normal P diet
Dietary Phosphorus Supplement Serum 1,25-(OH)2CC
0.1% Control <10pg/mL
0. 1% Cholecalciferol 248 ± 7 pg/mL
0. 1% 0.82% Pb+Cholecalciferol 94 ± 13 pg/mL
0.3% Control <10 pg/mL
0.3% Cholecalciferol 285±44pg/mL
0.3% 0.82% Pb+Cholecalciferol 245±46pg/mL
Effect of Pb on serum 1 ,25-(OH),CC levels in rats fed low Ca or high Ca diet
Dietary Calcium Supplement Serum 1,25-(OH)2CC
0.02% Control <10 pg/mL
0.02% Cholecalciferol (50ng/day) 754±18pg/mL
0.02% 0.82% Pb+Cholecalciferol 443 ± 79 pg/mL
1.2% Control <10pg/mL
1 .2% Cholecalciferol (50ng/day) 285 ± 44 pg/mL
1 .2% 0. 82% Pb+Cholecalciferol 245 ± 46 pg/mL
Rat No effects of Pb on plasma concentrations of vitamin D metabolites, 25-OH D3 or 1 ,25-
(OH2)D3, in pubertal male rats exposed to either 0.15% or 0.45% Pb acetate in drinking
water and maintained on an adequate diet.
Smith etal. (1981)
ug/lOOmL
3±1
9±8
352 ±40
<3
<3
284 ± 36
ug/lOOmL
<3
<3
284 ± 36
Offspring: Ronis et al. (2001 )
0.15%Pb = 67-
192 ug/dL; 0.45%
Pb = 120-
388 ng/dL
-------
Table AX5-8.2 (cont'd). Regulation of Bone Cell Function in Animals—Systemic Effects of Lead
>
X
to
Compound
Dose/Concentration
Duration Exposure
Route
PbCl2
0,0.2, or 0.8%
1 or 2 wks
In diet
PbCl2
0,0.2, or 0.8%
1 or 2 wks
In diet
Pb acetate
1% for 10 wks or
0.001-1% for 24 wks
In drinking water
Species Effects
Chicks Compared with control animals, Pb exposure significantly increased intestinal calbindin
protein and mRNA levels in addition to plasma 1,25-dihydroxy vitamin D concentration.
The effect was present after 1 wk of exposure and continued through the second week. In
calcium-deficient animals increased plasma 1,25-dihydroxy vitamin D and calbindin protein
and mRNA were significantly (p < 0.05) inhibited by Pb exposure in a dose dependent
fashion over the 2 wk experimental period.
Chicks Dose dependent increases in serum 1,25-(OH2)D3 levels (and Calbindin-D protein and
mRNA) with increasing dietary Pb exposure (0. 1% to 0.8%) in experiments performed on
Leghorn cockerel chicks fed an adequate calcium diet.
Rat Short term administration of 1 % Pb resulted in significant increases in bone Pb. Total
serum calcium and ionized serum calcium were significantly decreased, as compared to
controls. Circulating levels of 1 ,25-(OH2)D3 were also decreased, though the rats were
maintained on a normal calcium diet (0.95%). In the long term study, a dose-dependent
increase in parathyroid weight occurred with increasing exposure to Pb in drinking water.
Blood Level
None given
None given
Short term (lOwk)
study:
Control:
< 0.02 ug/1
Pb-exposed:
> 5 ug/1
Reference
Fullmer (1995)
Fullmer et al.
(1996)
Szaboetal. (1991)
Short term (10 wks) exposure Controls
Serum Calcium (mM) Ionized Calcium 2.42 ± 0.03
(mM) 1,25(OH)2D3 (pM) 1.25 ± 0.03
Parathyroid Weight (ug/gland) 232 ± 18.9
*p<0.01 96 ±34
Pb-exposed
2.32 ±0.02*
1.15±0.03*
177 ±10.8*
178 ±25*
Long term (24 wks) exposure
Pb in water
0%
0.001%
0.01%
0.1%
1.0%
p<0.01
Normalized Parathyroid
Weight (ug/g body wt)
0.50 ±0.06
0.72 ± 0.25
0.81 ±0.28
0.94 ±0.27
0.81 ±0.29*
l,25(OH)2D3(pM)
241 ± 32
188 ±27
163 ±17
206 ± 24
144 ± 33*
-------
>
X
to
oo
Table AX5-8.2 (cont'd). Regulation of Bone Cell Function in Animals—Systemic Effects of Lead
Compound
Dose/Concentration
Duration Exposure
Route
Pb nitrate
0.02% (125 ppm)
GD5 to 1 day before
sacrifice
In drinking water
Pb acetate
0.05% to 0.45%
GD 5 through sacrifice
of pups at 21, 35, 55,
and 85 days
In drinking water
Species Effects
Rat Basal release of growth hormone from control and Pb-exposed pups at age 49 days was not
significantly different. Growth hormone releasing factor- stimulated release of growth
hormone from pituitaries of Pb-exposed pups was smaller than the stimulated release of
growth hormone from pituitaries of control animals (75% increase over baseline vs. 171%
increase, respectively), but the difference did not achieve significance (P = 0.08). Growth
hormone content of the pituitary glands was also not influenced by Pb exposure.
Rat Pituitary GH content (ug/mg) at postnatal day 55:
Control Male Pups = 56.6 ± 8.0; Female Pups = 85.6 ± 9.3
0.05% Pb Male Pups = 107.2 ± 10.5*; Female Pups = 116.2 ±9.1
0.15% Pb Male Pups = 96.8 ± 5.0*; Female Pups = 105.1 ± 7.3
0.45% Pb Male Pups = 106.0 ± 9.8*; Female Pups = 157.0 ± 9.9*
*significantly different from control, p < 0.05
Blood Level
Rat Pups
5 days old: 43. 3 ±
2.7 ug/dL
49 day sold: 18.9
± 0.7 ug/dL
(females: 19.94±
0.8 ug/dL; males:
17.00 ±1.1 ug/dL)
Offspring:
0.05% Pb = 49 ± 6
ug/dL; 0.1 5% Pb =
126 ±16 ug/dL;
0.45% Pb = 263 ±
28 ug/dL
Reference
Camoratto et al.
(1993)
Ronis et al.
(1998b)
Abbreviations
mg—milligram
h—hour
1,25-(OH)2CC—1,25-dihydroxycholecalcigerol
ug—microgram
25-OHD3—25-hydroxycholecalciferol
PbCl2—lead chloride
1,25-(OH)2 D3—vitamin D3
kg—kilogram
mg%—milligram percent
pg—picogram
GD—gestational day
mM—millimolar
Pb—lead
pM—picomolar
i.v.—intravenous
%—percent
mL—milliliter
dL—deciliter
mRNA—messenger ribonucleic acid
ppm—parts per million
GH—growth hormone
min—minute
-------
Table AX5-8.3. Bone Cell Cultures Utilized to Test Effects of Lead
>
X
to
VO
Compound
Dose/Concentration
Duration Exposure
Route
210Pb nitrate
S^M
20 hours
In medium
Pb acetate
0 to 50 nM
20 h
In medium
Species
Effects
Blood Level
Reference
Stable "Pb"
5 mg/mL in drinking
water given during
gestation.
On GDI 8, SOnCi
210Pb given i.v. to
pregnant dams
210Pb nitrate
6.5 to 65 |iM
5 min to 2 h
In medium
Rat
(fetal bone
organ culture)
Mice
(bone cell
isolation from
calvaria)
PTH (3885 lU/mg bone) enhanced cell-mediated release of 210Pb from bone. Release Not given/not
of 210Pb was accompanied by proportional loss of
bones.
Time: Release of 210Pb (EM/CM ratio)
Omin 1.00
10 min 0.82 ±0.05
2hr 1.12 ±0.04
6hr 1.59 ±0.08*
24 hr 3.69 ±0.15*
48 hr 3.75 ±0.09*
48 hr 0.78 ± 0. 14* (in presence of 30 mU/mL
*Different from 1 .00, p < 0.01 .
Uptake of 210Pb by OC cells rapid.
stable Pb and calcium from treated applicable
salmon calcitonin)
Not applicable
Rosen and Wexler
(1977)
Rosen (1983)
OC cells have greater avidity for Pb compared to OB cells.
OC cell uptake of Pb almost linear vs. little increase in Pb uptake by OB cells with
increasing Pb concentrations in media.
Mice
(osteoclastic
bone cell
isolation from
calvaria)
Mice
(osteoclastic
bone cell
isolation from
calvaria)
15-30% release of 210Pb label occurred in OC cells over 2 h time period.
Physiological concentrations of PTH resulted in marked increase in 210Pb and 45Ca
uptake by OC cells. 210Pb uptake linear over PTH concentrations of 50 to 250 ng/mL).
Media concentrations of Pb >26 |iM enhanced calcium uptake by cells.
Three readily exchangeable kinetic pools of intracellular Pb identified, with the
majority (—78%) associated with the mitochondrial complex.
Cultures were labeled with 45Ca (25 (iCi/mL) for 2 or 24 h and kinetic parameters
were examined by analysis of 45Ca washout curves.
In kinetic analysis using dual-label (1-2 (iCi/mL 210Pb and 25 (iCi/mL 45Ca) wash out
curves, the Ca:Pb ratios of the rate constants were -1:1, suggesting similar cellular
metabolism.
Not applicable
Not applicable
Pounds and Rosen
(1986)
Rosen and Pounds
(1988)
-------
Table AX5-8.3 (cont'd). Bone Cell Cultures Utilized to Test Effects of Lead
>
X
Compound
Dose/Concentration
Duration Exposure
Route
Pb acetate and 210Pb
label
0-100 uM
20 hr
In medium
Pb acetate
5 or 25 uM
Up to 5 hr
In medium
Pb nitrate
5 uM
20 min
In medium
Pb2+
5 or 12.5 uM
Up to 100 min
In medium
Species
Mice
(osteoclastic
bone cell
isolation from
calvaria) and
Rat
Osteo sarcoma
Cells
(ROS 17/2.8)
Rat
Osteo sarcoma
Cells
(ROS 17/2.8)
Rat
(osteoblastic
bone cell
isolation from
calvaria)
Rat
(osteoblastic
bone cell
isolation from
calvaria)
Effects Blood Level
Concentrations as high as 100 uM did not cause toxicity in either cell culture. There Not applicable
was a slight decrease in growth of ROS cells at 5 uM Pb concentration and a 50%
decrease in growth at 25 uM Pb at day 9.
210Pb washout experiments with both cell cultures indicated similar steady-state Pb
kinetics and intracellular Pb metabolism. Both cell cultures exhibited one large,
slowly exchanging pool of Pb, indicative of the mitochondrial pool.
Used 19F NMR in combination with 1 ,2-bis(2-amino-5-fluorophenoxy )ethane- Not applicable
N,N,N',N'-tetraacetic acid (5F-BAPTA) to distinguish and measure concentrations
of Pb2+ and Ca2+ in aqueous solution.
Basal concentration of [Ca +]i was 128 ± 24 nM. Treatment of cells with 5 and 25
uMPb2+ produced sustained 50% and 120% increases in [Ca2+];, respectively, over a
5 hour exposure period.
At a medium concentration of 25 uM Pb2+ a measurable entry of Pb2+into the cells
([Pb2+], of 29 ± 8 pM) was noted.
Pb (5 uM) linearly raised the emission ratio of FURA-2 loaded cells 2-fold within 20 Not applicable
min of application, most likely due to increase in [Pb2+]i rather than increase in
[Ca2!.
Intracellular calcium increased even in the absence of extracellular calcium.
5 or 12.5 uM Pb2+ applied simultaneously with re-added calcium reduced immediate Not applicable
CRAC to 70% or 37% of control value, respectively.
During CRAC a large influx of Pb + occurred, leading to a 2.7-fold faster increase in
the FURA-2 excitation ratio. These effects were exclusive of any inhibitory action
of Pb2+on calcium ATPase activity.
Reference
Longetal. (1990)
Schanne et al.
(1989)
Schirrmacher et al.
(1998)
Wiemann et al.
(1999)
-------
Table AX5-8.3 (cont'd). Bone Cell Cultures Utilized to Test Effects of Lead
Compound
Dose/Concentration
Duration Exposure
Route
Species
Effects
Blood Level
Reference
>
X
Pb nitrate
0-150 uM
Up to 72 ru-
in medium
Pb acetate
0-25 uM
48 hr
In medium
Mice (bone
cell isolation
from parietal
bones)
Rat
Osteo sarcoma
Cells
(ROS 17/2.8)
Pb2+ concentrations of 50 |iM and above stimulated release of hydroxyproline and Not applicable
previously incorporated 45Ca from organ culture. This did not occur in bone
inactivated by freezing and thawing. Eel calcitonin, bafilomycin AI, and scopadulcic
acid B significantly inhibited Pb mediated 45Ca release. There was a high correlation
between 45Ca and PGE2 release (p < 0.001), inferring Pb-induced bone resorption
mediated by PGE2. This was further supported by the significant depression of Pb-
stimulated 45Ca release that occurred with concurrent exposure to 10 uM of either
indomethacin or flurbiprofen, both inhibitors of cyclooxygenase.
Osteocalcin production in cells treated with 100 pg 1,25-dihydroxyvitamin D3/mL of Not applicable
medium and 0 uMPb2+for 16, 24, or 36 h was 20.1 ± 2.1,23.5 ± 3.4, 26.1 ± 2.5 in cell
digests, and 87.2 ± 3.3, 91.6 ± 6.7, 95.1 ± 5.2 in the medium, respectively. The
presence of 25 uM Pb +in the medium, reduced osteocalcin levels to as low as 30% of
control levels.
Cells treated with 0, 5,10, or 25 uM Pb acetate for 24 h, followed by an additional
24 h exposure to 0 or 100 pg of 1,25-dihydroxy vitamin D3 and continued Pb2+
exposure, resulted in a concentration-dependent reduction of 1,25-dihydroxy vitamin
D3-stimulated osteocalcin secretion. 10 uM Pb resulted in medium osteocalcin levels
similar to control levels, however, 25 uM Pb resulted in about a 30% decrease.
Cellular osteocalcin levels were unaffected.
Miyahara et al.
(1995)
Long etal. (1990)
Pb glutamate
4.5x 10~5to
4.5 x 10~7M
2, 4, or 6 days
In medium
Pb glutamate
4.5 x 10~5M-10~7
1,3, or 5 days
incubation
In medium
M
Rat
Osteo sarcoma
Cells
(ROS 17/2.8)
Human
Dental Pulp
Cells
In the presence of serum in the cultures, concentrations of Pb2+ less than 4.5 x 10 5 M Not applicable Sauk et al. (1992)
had no effect on cell proliferation. In the absence of serum, 4.5 x 10 7 M Pb2+
increased proliferation at Day 4 and 4.5 x 10 6 M Pb2+ inhibited proliferation at Day 6.
Pb exposure for 48 h (4.5 x 10 6 M) significantly (p < 0.01) increased total protein
production in cells and media of cultures labeled with [ H] proline, but did not
increase collagen production. Protein synthesis and osteonectin were enhanced in
cells following Pb + exposure.
All concentrations significantly increased cell proliferation on Day 1, 3, and 5 of Not applicable Thaweboon et al.
exposure in serum free conditions. Pb exposure resulted in dose-dependent decrease (2002)
in intracellular protein and procollagen I production over 5 days. In presence of serum
only, 4.5 x 10~5M Pb2+ significantly increased protein production, however, at that
same concentration Pb significantly decreased osteocalcin production (i.e., reduced the
level of osteocalcin by 55% at 12 hr).
-------
Table AX5-8.3 (cont'd). Bone Cell Cultures Utilized to Test Effects of Lead
>
X
to
Compound
Dose/Concentration
Duration Exposure
Route
Pb glutamate
5-20 \iM
48 hr
In medium
Pb
0.5 to 5 uM
40min
In medium
Pb nitrate
5x 10~4to5x 10~15M
24 h
In medium
Pb acetate
2 to 200 uM
72 h
In medium
Species
Rat
Osteo sarcoma
Cells
(ROS 17/2.8)
Rat
Osteo sarcoma
Cells
(ROS 17/2.8)
Rat
Osteosarcoma
Cells
(ROS 17/2.8)
Rat
Osteosarcoma
Cells
(ROS 17/2.8)
Effects Blood Level
Cells treated with 0, 5, 10, or 20 uM Pb acetate for 24 h, followed by an additional Not applicable
24 h exposure to 0 or 100 pg of 1,25-dihydroxy vitamin D3 and continued Pb +
exposure, resulted in a significant (p < 0.05 or less) reduction of osteocalcin secretion,
both in the presence and absence of 1,25-dihydroxy vitamin D3 at all Pb2+
concentrations. This effect is not mediated by PKC.
1 and 5 |iM Pb2+ significantly increased [Ca2+]; in the absence of 1,25- Not applicable
dihydroxyvitamin D3 and significantly reduced the peak elevation in [Ca2+]j induced
by 1,25-dihydroxy vitamin D3.
Simultaneous treatment of previously unexposed cells to Pb2+and 1,25-
dihydroxy vitamin D3 produced little reduction in the 1,25-dihydroxy vitamin D3-
induced 45Ca uptake, while 40 min of treatment with Pb2+ before addition of 1,25-
dihydroxy vitamin D3 significantly reduced the 1,25-dihydroxy vitamin D3-induced
increase in 45Ca influx.
Osteocalcin secretion significantly reduced below control values by culture with 1 uM Not applicable
Pb2+ in the presence or absence of added 1 ,25-dihydroxy vitamin D3 or 1 ,25-
dihydroxy vitamin D3 and IGF-I. Inhibition of osteocalcin secretion was almost
complete in either hormone- stimulated or basal cultures with the addition of 100 uM
Pb +. Cellular alkaline phosphatase activity paralleled those of osteocalcin, though
there was no response to IGF-I alone or in combination with 1,25-dihydroxy vitamin
D3. Pb2+at 10~15, 10~12, and 10~9 to 10~7M did not influence DNA contents of cell
cultures, but 1 uM significantly (p < 0.05) inhibited basal cultures and those with IGF-
I + D3. Cell cultures exposed to 1 ,25-dihydroxyvitamin D3 and Pb2+ were inhibited at
10uMPb2+.
Pb (2 to 200 uM) had no effect on cell number or DNA and protein synthesis. Not applicable
Alkaline phosphatase activity was significantly reduced (p < 0.001) by Pb in a dose-
and time-dependent manner.
Pb Concentration. Alkaline Phosphatase Inhibition
2uM. 10.0 ±1.1%
20 uM. 22.0 ± 6.4%
200 uM. 57.8 ±8. 8%
Reductions in alkaline phosphatase mRNA levels mirrored Pb + -induced inhibition of
enzyme activity.
Reference
Guity et al. (2002)
Schanne et al.
(1992)
Angle etal. (1990)
Klein and Wiren
(1993)
-------
Table AX5-8.3 (cont'd). Bone Cell Cultures Utilized to Test Effects of Lead
>
X
Compound
Dose/Concentration
Duration Exposure
Route
Unidentified Pb2+
Various incubation
times
Not applicable
Unidentified Pb2+
Various incubation
times
Not applicable
Pb acetate
10 uM
2h
In medium
Pb acetate
5 or 25 uM
Up to 24 h
In medium
Pb acetate
5 or 25 uM
20 h
In medium
Species
Bovine
(Bovine-
derived
osteocalcin)
Bovine
(Bovine-
derived
osteocalcin)
Rat
Osteosarcoma
Cells
(ROS 17/2.8)
Rat
Osteosarcoma
Cells
(ROS 17/2.8)
Rat
Osteosarcoma
Cells
(ROS 17/2.8)
Effects Blood Level
Binding studies of Ca2+to osteocalcin suggested a single binding site with a Not applicable
dissociation constant (Kd) of 7 ± 2 uM for Ca-osteocalcin. Competitive displacement
experiments by addition of Pb2+ indicated the Kd for Pb-osteocalcin is 1 .6 ± 0.42 nM,
~3 orders of magnitude higher.
Circular dichroism indicated Pb + binding induced a structural change in osteocalcin Not applicable
similar to that found in Ca2+ binding, but at 2 orders of magnitude lower concentration.
Pb2+ has 4 orders of magnitude tighter binding to osteocalcin (Kd = 0.085 uM) than
Ca2+ (Kd = 1 .25 mM). Hydroxyapatite binding assays showed similar increased
adsorption of Pb2+ and Ca2+to hydroxyapatite, but Pb2+ adsorption occurred at a
concentration 2-3 orders lower than Ca2+.
Pb + treatment reduced the unidirectional rate of ATP synthesis (P; to ATP) by a factor Not applicable
of 6 or more (AM/H,: Control = 0.18 ± 0.04, Pb2+< 0.03). Intracellular free Mg2+
concentration decreased 21% after 2 h of 10 uM Pb + treatment (0.29 ± 0.02 mM prior
to Pb2+ treatment and 0.23 ± 0.02 mM after 2 h of Pb2+ treatment, p < 0.05).
5 uM Pb + significantly altered effect of EGF on intracellular calcium metabolism. Not applicable
In cells treated with 5 uM Pb2+ and 50 ng/mL EGF, there was a 50% increase in total
cell calcium over cells treated with 50 ng/mL EGF alone.
Treatment with 400 ng/mL culture medium for 1 h or with 25 uM Pb2+ for 20 h Not applicable
increased total cell calcium:
Treatment Cell Calcium
Control 7.56 ± 1 .05 nmol/mg protein
PTH (400 ng/mL) 23.28 ± 1 .40* nmol/mg protein
Pb (25 uM) 1 1 .37 ± 0.57* nmol/mg protein
PTH + Pb 37.88 ± 4.21* nmol/mg protein
* p < 0.05 from control
Reference
Dowdetal. (1994)
Dowdetal. (2001)
Dowdetal. (1990)
Long and Rosen
(1992)
Longetal. (1992)
-------
Table AX5-8.3 (cont'd). Bone Cell Cultures Utilized to Test Effects of Lead
>
X
Compound
Dose/Concentration
Duration Exposure
Route
Pb acetate
Krnto 1(T7M
3 min
In medium
Pb acetate
0.5 to 60 uM
24 to 48 h
In medium
Pb acetate or Pb
chloride
O.lto200 uM
Species
Rat
Osteo sarcoma
Cells
(ROS 17/2.8)
Human
Osteosarcoma
Cells (HOS
TE85)
and
Rat
Osteosarcoma
Cells
(ROS 17/2.8)
Chick growth
plate
chondrocytes
Effects Blood Level
Treatment of ROS cells with Pb at 1 or 5 uM concentrations produced a rise in [Ca2+]j Not applicable
to 170 nM and 230 nM, respectively, over the basal level of 125 nM. An elevation in
[Ca2+]i to 210 nM occurred during treatment with an activator of PKC, phorbol 12-
myristate 13-acetate (10 uM). Pretreatment with a selective inhibitor of PKC,
calphostin C, did not change basal [Ca2+]j, but prevented the Pb-induced rise in [Ca2+];.
Free Pb2+activated PKC in a range from 10 u to 10 7 M, with a Kcat (activation
constant) of 1 . 1 x 10 10 M and a maximum velocity (Vmax) of 1 .08 nmol/mg/min
compared with Ca activation of PKC over a range of 10 8 to 10 3 M, with a Kcat of
3.6x10 M, and a Vmax of 1 . 12 nmol/mg/min.
HOS TE 85 Cells Not applicable
Inhibition of proliferation (IC50) = 4 |iM Pb
Cytotoxicity = 20 uM Pb
ROS 17/2.8 Cells
Inhibition of proliferation (IC50) = 6 |iM Pb
Cytotoxicity = 20 uM Pb
Highest Pb concentration in both cell types found in mitochondrial fraction.
Growth plate chondrocytes were exposed to 3 or 30 uM for up to 6 days. Maximal Not applicable
inhibition of cell proliferation as measured by thymidine incorporation occurred after a
3-day exposure to Pb. A similar 40% inhibition was found at both concentrations.
Reference
Schanne et al.
(1997)
Angle etal. (1993)
Hicks etal. (1996)
24 h to 6 days
In medium
Higher concentrations (up to 100 uM) did not produce further inhibition.
In cultures treated for 24 h, Pb produced a dose-dependent inhibition of alkaline
phosphatase, with 10 uM producing maximal inhibition (40-50% inhibition). Effects
of Pb on proteoglycan synthesis were not found until after 48 h of exposure, with
maximal effect after 72 h of exposure (twofold, 30 uM). Pb exposure (10 to 200 uM)
for 24 h produced a dose-dependent inhibition of both type II and type X collagen
synthesis.
-------
Table AX5-8.3 (cont'd). Bone Cell Cultures Utilized to Test Effects of Lead
Compound
Dose/Concentration
Duration Exposure
Route
Pb acetate
0.1 to 30 uM
24 h
In medium
Species
Chicken
growth plate
and sternal
chondrocytes
Effects Blood Level
A dose-dependent inhibition of thymidine incorporation into growth plate Not applicable
chondrocytes was found with exposure to 1-30 uM Pb for 24 h. A maximal 60%
reduction occurred at 30 uM. Pb blunted the stimulatory effects on thymidine
incorporation produced by TGF-p1! (24% reduction) and PTHrP (19% reduction),
however, this effect was less than with Pb alone. Pb (1 and 10 uM) increased type X
collagen in growth plate chondrocytes ~5. 0-fold and 6.0-fold in TGF-p1! treated
cultures and 4.2-fold and 5. 1 -fold in PTHrP treated cultures when compared with
controls, respectively. Pb exposure alone reduced type X collagen expression by
70-80%.
Reference
Zuscik et al.
(2002)
>
X
Abbreviations
Pb—lead
(iCi—microCurie
IU—international units
hr—hour
OB—osteoblast
5F-BAPTA—l,2-bis(2-amino-5-fluorophenoxy)ethane-N,N,N',N'-tetraaceticacid
[Pb +]i—free intracellular lead
FURA-2—l-[6-Amino-2-(5-carboxy-2-oxazolyl)-5-benzofuranyloxy]-2-(2-amino-5-
methylphenoxy) ethane-N,N,N',N'-tetraacetic acid
M—molar
DNA—deoxyribonucleic acid
AM—decrease in magnetization of intracellular Pi upon prolonged saturation of gamma-
phosphate of ATP
mM—millimolar
Kcat—activation constant
IC50—inhibitory concentration 50%
mg—milligram
210Pb—lead-210 radionuclide
EM—experimental medium
mU—milliunits
45Ca—calcium-45 radionuclide
CRAC—calcium release activated calcium reflux
pg—picogram
mRNA—messenger ribonucleic acid
ng—nanogram
Vmax—maximum velocity
TGF-pl—transforming growth factor-beta 1
mL—milliliter
i. v. —intravenous
CM—control medium
uM—micromolar
ng—nanogram
[Ca2+]i—free intracellular calcium
PGE2—prostaglandin E2
PKC—protein kinase C
Kd—dissociation constant
nmol—nanomole
HOS TE 85 cells—human osteosarcoma cells
PTHrP—parathyroid hormone-related protein
GD—gestational day
PTH—parathyroid hormone
min—minute
OC—osteoclast
ROS 17/2.8—rat osteosarcoma cells
nM—nanomolar
h—hour
IGF-I—insulin growth factor I
ATP—adenosine triphosphate
EGF—epidermal growth factor
-------
Table AX5-8.4. Bone Lead as a Potential Source of Toxicity in Altered Metabolic Conditions
Compound
Dose/Concentration
Duration Exposure
Route
Species
Effects
Blood Level
Reference
>
X
Pb acetate
200 ug/mL
105 days prior to mating
or 105 days prior to
mating and during
gestation and lactation
(160 days)
In drinking water
Pb acetate
12 mM
8 wks prior to mating
and during gestation
In drinking water
Pb acetate
100 ppm
(A) Exposure for 158 ±
2 days from 21 days of
age to midlactation; (B)
Exposure 144 ± 2 days
from day 21 up to
delivery; (C) Exposure
only during lactation;
(D, E, and F) groups of
nonpregnant rats
exposed for periods
equivalent to groups A,
B and C, respectively.
In drinking water
Mice
Rat
Rat
Results suggested very little Pb was transferred from mother to fetus during
gestation, however, Pb transferred in milk and retained by the pups accounted
for 3% of the maternal body burden of those mice exposed to Pb prior to
mating only. The amount of Pb retained in these pups exceeded that retained
in the mothers, suggesting lactation effectively transfers Pb burden from
mother to suckling offspring. Transfer of Pb from mothers was significantly
higher when Pb was supplied continuously in drinking water, rather than
terminated prior to mating.
Considerably higher lactational transfer of Pb from rat dams compared to
placental transfer was reported. Continuous exposure of rat dams to Pb until
day 15 of lactation resulted in milk Pb levels 2.5 times higher than in whole
blood, while termination of maternal Pb exposure at parturition yielded
equivalent blood and milk levels of Pb, principally from Pb mobilized from
maternal bone.
In rats exposed to Pb 144 days prior to lactation (B), the process of lactation
itself elevated blood Pb and decreased bone Pb, indicating mobilization of Pb
from bone as there was no external source of Pb during the lactation process.
Rats exposed to Pb for 158 days (A)(144 days prior to lactation and 14 days
during lactation) also experienced elevated blood Pb levels and loss of Pb from
bone. Pb exposure only during the 14 days of lactation was found to
significantly increase intestinal absorption and deposition (17 fold increase) of
Pb into bone compared to nonpregnant rats, suggesting enhanced absorption of
Pb takes place during lactation. The highest concentration of Pb in bone was
found in nonpregnant, nonlactating control animals, with significantly
decreased bone Pb in lactating rats secondary to bone mobilization and transfer
via milk to suckling offspring.
Not given
Concentration (ug/1) in
whole blood at day 15 of
lactation:
Controls = 14 ± 4; Pb-
exposed until parturition =
320 ± 55; Pb-exposed
until day 15 of lactation =
1260 ±171*
*p < 0.001 compared with
dams at parturition.
Concentration (ug/dL) in
whole blood at day 14 of
lactation or equivalent:
Group A =31.2 ±1.1;
Group B = 28.0 ± 1.7;
Group D = 27.3 ±2.2;
Group E = 24.7 ±1.2
Keller and Doherty
(1980)
Palminger Hallen
etal. (1996)
Maldonado-Vega
etal. (1996)
-------
Table AX5-8.4 (cont'd). Bone Lead as a Potential Source of Toxicity in Altered Metabolic Conditions
Compound
Dose/Concentration
Duration Exposure
Route
Species
Effects
Blood Level
Reference
>
X
Pb acetate Rat
100 ppm
(A) Exposure for 158 ±
2 days from 21 days
through 14 days of
lactation; (B)
Nonpregnant control
Group A; (C) Exposure
144 ±2 days from day
21 up to delivery; (D)
Nonpregnant control
Group C; (E) Lactating
rats not exposed to Pb;
(F) Nonpregnant rats
not exposed to Pb.
In drinking water
Pb acetate Rat
250 mg/mL
Beginning at 5 wks of
age, rats exposed to Pb
for 5 wks, followed by
no additional exposure.
In drinking water
When dietary calcium was reduced from the normal 1 to 0.05%, bone calcium
concentration decreased by 15% and bone Pb concentration decreased by 30%
during the first 14 days of lactation. In nonlactating rats on the 0.05% calcium
diet, there were also decreases in bone calcium, but no incremental bone
resorption nor Pb efflux from bone, suggesting the efflux from bone during
lactation was related to bone resorption. Enhancement of calcium (2.5%) in
the diet of lactating rats increased calcium concentration in bone by 21%, but
did not decrease bone resorption, resulting in a 28% decrease in bone Pb
concentration and concomitant rise in systemic toxicity.
Demonstrated adverse effects in rat offspring bom to females whose exposure
to Pb ended well before pregnancy. Five wk-old-female rats given Pb acetate
in drinking water (250 mg/mL) for five wks, followed by a one mo period
without Pb exposure before mating. To test the influence of dietary calcium
on Pb absorption and accumulation, some pregnant rats were fed diets
deficient in calcium (0.1%) while others were maintained on a normal calcium
(0.5%) diet. All Pb-exposed dams and pups had elevated blood Pb levels;
however, pups bom to dams fed the diet deficient in calcium during pregnancy
had higher blood and organ Pb concentrations compared to pups from dams
fed the normal diet. Pups bom to Pb-exposed dams had lower mean birth
weights and birth lengths than pups born to non-Pb-exposed control dams
(p < 0.0001), even after confounders such as litter size, pup sex, and dam
weight gain were taken into account.
Concentration (ng/dL) in
whole blood at day 14 of
lactation or equivalent:
Group B = 26.1 ±2.1,
Group A =32.2 ±2.7*;
Group D = 23.8 ±2.1,
Group C = 28.2 ± 2.2*;
Groups E and F = 5.1 ±
0.4.
* p < 0.01, compared to
appropriate control
Blood Pb concentration of
pups (nM): Low
calcium/no Pb = 0.137 ±
0.030°; Low calcium/Pb =
1.160 ±0.053A; Normal
calcium/No Pb = 0.032 ±
0.003°; Normal
calcium/Pb = 0.771 ±
0.056B.
Values that are not
marked by the same letter
are significantly different
(p<0.05).
Maldonado-Vega
et al. (2002)
Han et al. (2000)
-------
Table AX5-8.4 (cont'd). Bone Lead as a Potential Source of Toxicity in Altered Metabolic Conditions
Compound
Dose/Concentration
Duration Exposure
Route
Species
Effects
Blood Level
Reference
>
X
oo
Pb acetate
1500 ug/Common
Pb/kg/d
—10 yrs, replaced by a
204Pb-enriched dose
(50 days), then
206Pb-enriched dose
(50 days), and finally a
207Pb-enriched dose
(50 days, with reduced
concentration)
Orally, in gelatin
capsule
Nonhuman
Primate
Sequential doses of Pb mixes enriched in stable isotopes (204Pb, 206Pb,
and 207Pb) were administered to a female cynomolgus monkey (Macaco
fascicularis) that had been chronically administered a common Pb isotope mix.
The stable isotope mixes served as a marker of recent, exogenous Pb exposure,
while the chronically administered common Pb served as a marker of
endogenous (principally bone) Pb. From thermal ionization mass spectrometry
analysis of the Pb isotopic ratios of blood and bone biopsies collected at each
isotope change, and using end-member unmixing equations, it was determined
that administration of the first isotope label allowed measurement of the
contribution of historic bone stores to blood Pb. Exposure to subsequent
isotopic labels allowed measurements of the contribution from historic bone
Pb stores and the recently administered enriched isotopes that incorporated
into bone. In general the contribution from the historic bone Pb (common Pb)
to blood Pb level was constant (-20%), accentuated with spikes in total blood
Pb due to the current administration of the stable isotopes. After cessation of
each sequential administration, the concentration of the signature dose rapidly
decreased.
Total blood Pb range:
31.2 to 62.3 ug/lOOg.
Inskipetal. (1996)
Pb acetate
1300 to
1500 ug/Common
Pb/kg/d
-10 yrs, replaced by a
204Pb-enriched dose
(47 or 281 days), then
206Pb-enriched dose
(50 or 105 days), and
finally a 207Pb-enriched
dose (50 days, with
650 ug concentration in
only one primate)
Orally, in gelatin
capsule
Nonhuman Initial attempts to apply a single bone physiologically based model of Pb
Primate kinetics were unsuccessful until adequate explanation of these rapid drops in
stable isotopes in the blood were incorporated. Revisions were added to
account for rapid turnover of the trabecular bone compartment and slower
turnover rates of cortical bone compartment, an acceptable model evolved.
From this model it was reported that historic bone Pb from 11 yrs of
continuous exposure contributes —17% of the blood Pb concentration at Pb
concentration over 50 ug/dL, reinforcing the concept that the length of Pb
exposure and the rates of past and current Pb exposures help determine the
fractional contribution of bone Pb to total blood Pb levels. The turnover rate
for cortical (—88% of total bone by volume) bone in the adult cynomolgus
monkey was estimated by the model to be -4.5% per yr, while the turnover
rate for trabecular bone was estimated to be 33% per yr.
Various
O'Flaherty et al.
(1998)
-------
Table AX5-8.4 (cont'd). Bone Lead as a Potential Source of Toxicity in Altered Metabolic Conditions
Compound
Dose/Concentration
Duration Exposure
Route
Species
Effects
Blood Level
Reference
>
X
vo
Pb acetate
1100 to
1300 ug/Common
Pb/kg/d
-14 yrs, replaced by a
204Pb-enriched dose,
206Pb-enriched dose,
and/or finally a
207Pb-enriched dose of
varied durations and
concentrations.
Orally, in gelatin
capsule
Nonhuman Using the method of sequential stable isotope administration examined flux of
primate Pb from maternal bone during pregnancy of 5 female cynomolgus monkeys.
Blood Pb levels in maternal blood attributable to Pb from mobilized bone were
reported to drop 29 to 56% below prepregnancy baseline levels during the first
trimester of pregnancy. This was ascribed to the known increase in maternal
fluid volume, specific organ enlargement (e.g., mammary glands, uterus,
placenta), and increased metabolic activity that occurs during pregnancy.
During the second and third trimesters, when there is a rapid growth in the
fetal skeleton and compensatory demand for calcium from the maternal blood,
the Pb levels increased up to 44% over pre-pregnancy levels. With the
exception of one monkey, blood Pb concentrations in the fetus corresponded to
those found in the mothers, both in total Pb concentration and proportion of Pb
attributable to each isotopic signature dose (common = 22.1% vs. 23.7%,
204Pb = 6.9% vs. 7.4%, and 206Pb = 71.0% vs. 68.9%, respectively). Between
7 and 25% of Pb found in fetal bone originated from maternal bone, with the
balance derived from oral dosing of the mothers with isotope during
pregnancy.
In offspring from a low Pb exposure control monkey (blood Pb <5 ug/100 g)
-39% of Pb found in fetal bone was of maternal origin, suggesting enhanced
transfer and retention of Pb under low Pb conditions
Various, with total blood Franklin et al.
Pb as high as -65 ug/100 g (1997)
Pb acetate
250 mg/L
Exposure began either
at 5, 10, or 15 wks of
age and continued for a
total of 5 wks.
Drinking water
Rat Exposed rats for 5 wks to 250 mg/1 Pb as acetate in drinking water beginning
at 5 wks of age (young child), 10 wks of age (mid-adolescence), or 15 wks of
age (young adult), followed by a 4 wk period of without Pb exposure.
An additional group of rats were exposed to Pb beginning at 5 wks, but
examined following an 8 or 20 wk period after cessation of Pb. Significantly
lower blood and bone Pb concentrations were associated with greater age at
the start of Pb exposure and increased interval since the end of exposure.
Young rats beginning exposure to Pb at 5 wks and examined 20 wks after
cessation of exposure still, however, had bone Pb concentrations higher than
those found in older rats only 4 wks after cessation of exposure.
Pb concentration (uM)
4 wks after cessation of Pb
exposure:
Exposure started at 5 wks
of age =1.39 ±0.09;
Exposure started at 10 wks
of age =1.18 ±0.12;
Exposure started at 15 wks
of age = 0.82 ±0.05.
Han etal. (1997)
-------
Table AX5-8.4 (cont'd). Bone Lead as a Potential Source of Toxicity in Altered Metabolic Conditions
>
X
Compound
Dose/Concentration
Duration Exposure
Route
Pb acetate
50 ppm
11 mo
Drinking water
Pb acetate
0, 2, or 10 mg/kg/d
9. 5 mo
Drinking water
Pb acetate
7 yrs total
Drinking water
Species Effects
Rat Studied differences in tissue distribution of Pb in adult and old rats. Adult
(8 mo old) and old (16 mo old) rats were exposed to 50 ppm Pb acetate in
drinking water for 1 1 mo at which time the experiment was completed. Bone
(femur) Pb levels in older rats were found to be less than those in younger rats,
however, blood Pb levels were higher in the older rats. Brain Pb concentration
in the older rats exposed to Pb were significantly higher, and brain weight
significantly less than the brain Pb concentration and weights of unexposed
older control rats or adult rats exposed to Pb, suggesting a potential
detrimental effect. Authors suggested that a possibility for the observed
differences in tissue concentrations of Pb was due to changes in the capacity of
bone to store Pb with advanced age.
Rat Examined kinetic and biochemical responses of young (21 days old), adult
(8 mo old), and old (16 mo old) rats exposed to Pb at 0, 2, or 10 mg Pb
acetate/kg/d over a 9.5 mo experimental period. Results suggested older rats
may have increased vulnerability to Pb due to increased exposure of tissues to
Pb and greater sensitivity of the tissues to the effects of Pb.
Nonhuman In studies of bone Pb metabolism in a geriatric, female nonhuman primates
primate exposed to Pb —10 yrs previously, there were no significant changes in bone
Pb level over a 10 mo observation period as measured by 109CD K X-ray
Blood Level
Approximate median
values after 6 mo of
exposure:
Adult rats : 23 ug/dL
Old rats: 31 ug/dL
After 1 1 mo of exposure:
Adult rats: 16 ug/dL
Old rats: 31 ug/dL
Various from ~1 ug/dL
up to 45 ug/dL
Historic concentrations
during exposure: 44 to
89 ug/lOOmL.
Reference
Cory-Slechta et al.
(1989)
Cory-Slechta
(1990b)
McNeill et al.
(1997)
Pb (type unidentified)
occurring naturally in
diet (0.258 ng/mg dry
wt) and water
(5.45 ppb).
Exposure from age
1 mo up to 958 days.
Drinking water and diet
Mice
fluorescence. The mean half-life of Pb in bone of these animals was found to
be 3.0 ± 1.0 yrs, consistent with data found in humans, while the endogenous
exposure level due to mobilized Pb was
0.09 ± 0.02 ug/dL blood.
The Pb content of femurs increased by 83% (values ranged from 0.192 to 1.78
ng Pb/mg dry wt), no significant relationship was found between Pb and bone
density, bone collagen, or loss of calcium from bone. The results suggest
against low levels of bone Pb contributing to the osteopenia observed normally
inC57BL/6Jmice.
None given
Massie and Aiello
(1992)
-------
Table AX5-8.4. (cont'd). Bone Lead as a Potential Source of Toxicity in Altered Metabolic Conditions
Compound
Dose/Concentration
Duration Exposure
Route
Species
Effects
Blood Level
Reference
>
X
Pb acetate
250 mg/1
Exposure for 5 wks
Drinking water
Rat Rats were exposed to Pb for 5 wks, followed by a 4 wk washout period
without Pb to allow primarily accumulation in the skeleton. Rats were then
randomly assigned to a weight maintenance group (WM), a moderate weight
loss (MWL) group (70% of maintenance diet), or a substantial weight loss
(SWL) group (40% of maintenance diet) for a 4 wk period. At the end of this
experimental period the blood and bone levels of Pb did not differ between
groups, however, the amount and concentration of Pb in the liver increased
significantly.
Treatment Group Pb (nmol/g)
Femur WM 826 ± 70
MWL 735 ±53
SWL 935 ± 84
Spinal Column Bone
WM
MWL
SWL
702 ± 67
643 ± 59
796 ± 59
WM=1.25±0.10uM;
MWL = 1.16±0.10uM;
WM=1.32±0.10uM;
Han etal. (1996)
Pb acetate
250 ng/1
14 days
Drinking water
Rat Study was undertaken to determine the effect of weight loss and exercise on
the distribution of Pb. Weight loss secondary to dietary restriction was a
critical factor elevating organ Pb levels and, contrary to prior study (Han et al.
(1996)), elevated blood levels of Pb. No significant difference in organ or
blood Pb concentrations were reported between the exercise vs. no exercise
groups.
Graphs indicate
concentrations ranging
from 0.20 to 2.00 uM.
Han etal. (1999)
Abbreviations
ug—microgram
mL—milliliter
%—percent
mM—millimolar
1—liter
ppm—parts per million
dL—deciliter
mg—milligram
uM—micromolar
Pb—lead
kg—kilogram
g—gram
204-nu 206-nu 207
'Pb, 2°6Pb,
wt—weight
ppb—parts per billion
'Pb—Stable isotopes of lead 204,206, 207, respectively
-------
Table AX5-8.5. Uptake of Lead by Teeth
Compound
Dose/Concentration
Duration Exposure
Route
Species
Effects
Blood Level
Reference
>
X
to
Pb acetate
1 Hg/kg body weight
Single IP injection
Rat
Pb aerosol
77,249,orl546ng/m3
for 50 to 70 days
Inhalation
Pb acetate
0, 3, orlOppm
During pregnancy and
21 days of lactation
Drinking water
Rat
Rat
Uptake of Pb label into incisors of suckling rats:
0.7% of injected dose in 4 incisors of suckling rat after 24 h,
1.43% after 192 h. 0.6% of injected dose in 4 incisors of adult after 24 h,
0.88% after 192 h.
11 micrograms Pb/g incisor taken up in animals exposed to 77 ng/m3 for
70 days vs. 0.8 |ig Pb/g in control animals
13.8 |ig Pb/g incisor in rats exposed to 249 ng/m3 for 50 days
153 |ig Pb/g incisor in rats exposed to 1546 ng/m3 for 50 days
Pb concentration in teeth of offspring:
0 ppm group-Incisors (1.3 ppm), 1 st molars (0.3 ppm)
3 ppm group-Incisors (1.4 ppm), 1 st molars (2.7 ppm)
10 ppm group-Incisors (13.3 ppm), 1st molars (11.4 ppm)
Mean percent of dose after
time:
Suckling:
3.04% after 24 h
1.71% after 72 h
1.52% after 144 h
1.18% after 192 h
Adult:
6.40% after 24 h
3.41% after 24 h
1.92% after 24 h
1.04% after 72 h
0.72% after 144 h
0.48% after 192 h
Control: 2.6 |ig/dL
77|ig/m3: ll.Sjjg/dL
249 ng/m3: 24.1 ng/dL
1546ng/m3: 61.2ng/dL
Not given
Momcilovic and
Kostial(1974)
Grobleretal. (1991)
Grobleretal. (1985)
Abbreviations
Hg—microgram
kg—kilogram
IP—intraperitoneal
%—percent
h—hour
m—cubic meter
Pb—lead
g—gram
ppm—parts per million
-------
Table AX5-8.6. Effects of Lead on Enamel and Dentin Formation
Compound
Dose/Concentration
Duration Exposure
Route
Species
Effects
Blood Level
Reference
>
X
Pb "salt" Rat
0.075 mM/100 g ,
O.lSmM/lOOgor
1.5mM/100g
Single, SC injection
Pb acetate Rat
30 mg/kg
Single, i.v. injection
Pb acetate Rat
3 mg/kg
Single, i.v. injection
Pb acetate Rat
0 mg/1, 34 mg/1, or
170 mg/1
70 days
Drinking water
Pb acetate Rat
40 mg/kg
Single, IP injection
0.075 mM dose, no disruption of dentin and enamel.
0.15 mM dose, mild mineralization disruption of dentin and enamel.
1.5 mM dose, mild to moderate disruption of dentin and enamel.
Rapid rise in serum calcium and phosphorus after injection.
Formation of a "Pb line" in growing dentin within 6 hr after injection.
Production of a hypomineralized band in dentin.
Increased in relative amount of protein in enamel matrix.
Significant (p < 0.05) decrease in microhardness values of groups exposed
to Pb in regions of maturation enamel, but not fully mature enamel.
Delay in enamel mineralization in animals exposed to Pb.
Significantly (p < 0.05) reduced eruption rates at various time points
(days 8,14, 16, 22, 24,28) under hypofunctional conditions.
Not given
Not given
Not given
0 mg/1 group: 0 ppm
34 mg/1 group:
18.1 ppm
170 mg/1 group:
113.3 ppm
Days after injection
Odays: 48 ng/dL
10 days: 37 ng/dL
20 days: 28 ng/dL
30 days: 16 ng/dL
(Values estimated from
graph)
Eisenmann and Yaeger
(1969)
Appleton(1991)
Appleton(1992)
Gerlach et al. (2002)
Gerlach et al. (2000b)
Abbreviations
Pb—lead
mM—millimolar
g—gram
SC—subcutaneous
mg—milligram
kg—kilogram
i.v.—intravenous
1—liter
ppm—parts per million
IP—intraperitoneal
Hg—microgram
dL—deciliter
-------
Table AX5-8.7. Effects of Lead on Dental Pulp Cells
Compound
Dose/Concentration
Duration Exposure
Route
Pb glutamate
4.5 x l(r5M-l(T7M
1,3, or 5 days
incubation
Species
Human
Dental
Pulp Cells
Effects Blood Level
All concentrations significantly increased cell proliferation on Day 1, 3 and Not applicable
5 of exposure in serum free conditions. Pb exposure resulted in dose-
dependent decrease in intracellular protein and procollagen I production
over 5 days. In presence of serum only 4.5 x 1(T5M significantly increased
protein production. Pb significantly decreased osteocalcin production.
Reference
Thaweboon et al. (2002)
Abbreviations
Pb—lead
M—molar
>
X
-------
Table AX5-8.8. Effects of Lead on Teeth—Dental Caries
>
X
Compound
Dose/Concentration
Duration Exposure
Route
Pb acetate
0.5 mEq
84 days males
98 days females
Drinking water
Pb acetate
34ppm
Pre- and perinatal
Drinking water
Pb acetate
10or25ppmPb
3 wks
Drinking water
Species Effects
Hamster Significant increase in dental caries in male hamsters only
(85 mean molar caries score control vs. 118 for Pb exposed).
No significant difference in dental caries in female hamsters
(68 mean molar caries score control vs. 85 for Pb exposed).
Rat Pb exposure resulted in an almost 40% increase in the
prevalence of caries and nearly 30% decrease in stimulated
parotid salivary gland function.
Rat When 1 5 ppm fluoride was concurrently given in diet, Pb did
not increase prevalence of caries.
Blood Level
Not given
Control: <5 ng/dL
34ppmPb: 48 ±
13 ng/dL
Not given
Reference
Wisotzky and Hein (1958)
Watson etal. (1997)
Tabchouryetal. (1999)
Abbreviations
mEq—milliequivalents
d—days
ppm—parts per million
%—percent
Hg—microgram
dL—deciliter
-------
ANNEX TABLES AX5-9
AX5-146
-------
Table AX5-9.1. Studies on Lead Exposure and Immune Effects in Humans
>
X
Nature of
Exposure
Environmental
Occupational
Environmental
Environmental
Occupational
Environmental
Occupational
Occupational
Dose or Blood Lead Levels
(BLLs)
10. 1^18.2 ug/L(BLL)
22 ug/dL: <30 yrs old
23.0ug/dL: 30-39 yrs old
24. 1 ug/dL: > 40 yrs old
3.47-49. 19 ug/dL
2.56^13.69 ug/dL (mean
9.52 ug/dL)
Range of 10.0-400.9 ug/dL
Mean = 88.3 ug/dL
Controls all below 10 ug/dL
2.56^13.69 ug/dL
(BLLmean of 9.52 Ug/dL)
10—20 yr exposure (original
BLL mean 60 ug/dL; at time of
study BLL mean = 30 Ug/dL)
74.8 ± 17.8 ug/dL vs. 16.7 ±
5.0 ug/dL for controls
Sample Population
2nd grade children living near
industrial waste incinerator or other
industries causing pollution
Employees of Pb storage battery
factories in Korea
554 Men
52 Women
Children 6—11 yrs of age
30 girls
35 boys
Proximity to smelter
38 preschool children (3—6 yrs of
age);
35 controls
Male Pb-exposed workers
96 females
121 males
(3-6 yrs old)
30 Pb workers from battery
manufacturing plant (43 males and
21 females)
25 male storage battery workers
exposed >6 mo; age 33 ± 8.5 yrs
Reported Effects
Increased blood Pb concentration associated w/ increased IgE, especially above
28 ug/dL.
Also decreased T-cells, cytotoxic T-cells, and B-cells (non-linear relation).
Serum IgE higher when BLL >30 ug/dL — Correlation of BLL with serum IgE.
For employees less than 30 yrs old, IL-4 was lower when BLL >30 ug/dL.
Indirect (PHA) macrophage activation.
NO production negatively associated with BLL.
With proximity closest to smelter monocytes had increased superoxide anion
production by indirect and direct activation (positive correlation with BLL-
stronger for boys than girls).
Percent of CD4+ and CD4+CD+ cells decreased while CD8+ increased.
PHA-mitogen response decreased; and IFN-gamma production increased.
No effect on NK cytotox.
IgG and IgM lower in high BLL group (>9.52 ug/dL).
IgE greater in high BLL group (P < 0.10).
No difference among males but females exposed to higher Pb had significant
decreases in IgG and IgM and increased in IgE.
Correlation of BLL and serum IgE r = 0.48; P = 0.002.
Increased percentage of monocytes while percentage of B-cells, numbers of
lymphocytes, monocytes, and granulocytes decreased.
Decreased blood hemoglobin, TCD4+ cells, IgG, IgM, C3 and C4 compliment
proteins.
Increased zinc protoporphyrin.
Reference
Karmaus et al.
(2005)
Heo et al.
(2004)
Pineda-
Zavaleta et al.
(2004)
Zhao et al.
(2004)
Mishra et al.
(2003)
Sun et al.
(2003)
Sun et al
.(2003)
Basaran and
Undeger
(2000)
Impaired neutrophil chemotaxis and random migration.
-------
Table AX5-9.1 (cont'd). Studies on Lead Exposure and Immune Effects in Humans
Nature of Dose or Blood Lead Levels
Exposure (BLLs)
Sample Population
Reported Effects
Reference
Environmental
Epidemiological
study
Occupational
Occupational
X
1.7-16.1 ug/dL
(Range in <3 yr old group)
Blood Pbs from 1-45 ug/dL
BLL=39
Range 15-55 ug/dL
Pb workers with BLL between
7-50 ug/dL; mean 19 ug/dL
1561 children and adults in high Pb
community
480 controls
Urban Children population in
Missouri; 56% male
279 children 9 mo—6 yr of age
145 Pb exposed workers
84 controls
71 male chemical plant workers vs.
29 controls
6-35 mo: Sarasua et al.
increased IgA, IgG, IgM, number and proportion of B lymphocytes (2000)
decreased proportion of T-lymphocytes especially true when BLL > 15 ug/dL
>3 yrs of age-no differences.
Correlation of blood Pb levels and serum IgE levels in Missouri children. Lutz, et al.
(1999)
No major effects; only subtle effects. Pinkerton
Elev. B cells elevated CD4+/CD45RA+ cells. et a1' (1998)
Deer. Serum IgG.
T cell populations, Sata et al.
Naive T cells correlated positively with blood PB levels. Memory T cells (1998)
reduced with Pb.
OO
Occupational Exposed—Range of 38-
100 |ig/dL mean = 74.8 ug/dL;
Controls 11—30 ug/dL mean =
16.7 |ig/dL (high controls!)
Occupational BLL 12-80.0 ug/dL
Occupational Males
high BLL > 25 ug/dL
lower BLL <25 ug/dL
control BLL < 10 ug/dL
Occupational >60 ug/dL for group showing
best IgE effect
Occupational BLL 14.8-91.4 ug/dL
In vitro 207-1035 ug/L
25 Male battery plant workers vs.
25 controls
33 male workers in a storage
battery plant
51 Firearms instructors (high and
lower) vs. controls
2 groups of male workers
occupationally exposed
Absolute and relative numbers of CD4+ T cells reduced in exposed group.
IgG, IgM C3 and C4 serum levels all lower in workers.
No changes in serum Igs of PHA response of PBMC.
T cell phenotypes and response — Pb reduced relative CD3+ cells and relative and
absolute CD4+ cells also reduced PHA (high Pb)and PWM mitogen responses,
reduced MLR also(high Pb).
IgE positively correlated with BLL.
39 male workers of storage battery Impaired neutrophil migration.
P Impaired nitroblue tetrazolium positive neutrophils.
(4 yr mean exposure)
Greater for those exposed up to 1 yr than those with longer exposure "safe" levels
of Pb can still cause immunosuppression.
Human lymphocytes from adults Pb associated with greater IgG production after stimulation with PWM-not dose
25^14 yrs of age dependent.
Undeger et al.
(1996)
Queiroz et al.
(1994)
Fischbein
etal. (1993)
Horiguchi
et al. (1992)
Queiroz et al.
(1993)
Borella and
Giardino
(1991)
-------
Table AX5-9.1 (cont'd). Studies on Lead Exposure and Immune Effects in Humans
>
X
Nature of
Exposure
Occupational
Occupational
Occupational
Occupational
Environmental
Occupational
Environmental
Dose or Blood Lead
Levels (BLLs)
33.2 ug/dL in Pb-exposed
group
2.7 ug/dL in controls
10 Pb exposure workers vs.
controls
Worker BLLs of 41-50 ug/dL
No controls >19 ug/dL
Blood Pbs 64 ug/dL
Range 2 1-90
Comparison of workers with
25—53 ug/dL vs. controls with
8-17 ug/dL
Near smelter BLLs varied
seasonally 25—45 ug/dL
Control area BLLs varied
seasonally 10-22 ug/dL
Workers (18-85. 85.2 ug/dL
BLL)
controls (6.6-20.8 ug/dL BLL)
12 Afr.- American children
BLLs41-51ng/dL;
Sample Population
10 Male workers in scrap metal
refinery vs. 10 controls
39 male workers in Pb exposed
group
Workers exposure to Pb
Boys and girls —11.5 yrs old living
near Pb smelting plant
73 workers vs. 53 controls
12 African American preschool
children vs. 7 controls
Reported Effects
PMN chemotaxis reduced to 2 different chemoattractants.
ConA-generated suppressor cell production — increased.
Some other cellular parameters unchanged.
PHA response of lymphocytes from workers decreased.
No change in serum Ig levels PHA response of cells or NK activity.
Higher BLL associated with: decreased A-amino levulinic acid dehydrogetase.
Decreased IgM and secretory IgA.
Inversely related to IgG.
Negative correlation of BLL and serum IgG and C3.
Positive correlation of BLL and saliva IgA.
No difference in anti-tetanus antibody levels or in complement levels.
Reference
Valentino
etal. (1991)
Cohen et al.
(1989)
Alomran and
Shleamoon
(1988)
Kimber et al.
(1986)
Wagnerova
et al. (1986)
Ewers et al.
(1982)
Reigart and
Graber(1976)
7 controls BLLs 14-30 ug/dL
-------
Table AX5-9.2. Effect of Lead on Antibody Forming Cells (In Vitro Stimulation)
X
Species
Mouse
Mouse
Mouse
Mouse
Mouse
Mouse
Mouse
Mouse
Mouse
Rat
Mouse
Mouse
Strain/Gender
Various
Various
CBA/J females
BDFi females
CBA/J females
CBA/J
CBA/J females
Swiss males
Swiss
SD
Swiss
Swiss
Age
Adult
Adult
Adult
Adult
Adult
Adult
Adult
Adult
Adult
Neonate-
Juvenile
Adult
Adult
In Vivo/ Ex
Effect Vivo
|AFC No
AFC No change Yes
|AFC primary response No
|AFC — T dependent antigen
AFC — T independent antigen, no
change
|AFC Yes
TAFC No
TAFC No
|AFC Yes
|AFC Yes
|AFC (IgM) Yes
tAFC-IgM Yes
|AFC-IgG
|AFC-IgM Yes
|AFC-IgG
Lead Dose/
Concentration
10 uM
10 mM in water
100 uM
50 ug Pb acetate in water
0.08 mM and
0.4mM
10~5M
10~4M
O.SppmtetraethylPb
1300 ppm
25 ppm and 50 ppm
4 mg i.p. or oral
13.75 ppm-1,375 ppm
Duration
of Exposure
5 days
8 wks
5 days
3 wks
4 wks
5 days
1 hr preincubation
3 wks
10 wks
3 wks prenatal and
6 wks postnatal
Single dose
8 wks
Reference
McCabe and
Lawrence (1991)
Mudziuski et al.
(1986)
Warner and
Lawrence (1986)
Blakley and
Archer (1981)
Lawrence (198 la)
Lawrence (1981b)
Lawrence (1981c)
Blakley et al.
(1980)
Koller and Roan
(1980)
Luster et al ( 1978)
Koller et al.
(1976)
Koller and
Kovacic (1974)
-------
Table AX5-9.3. Studies Reporting Lead-induced Suppression of Delayed Type Hypersensitivity and Related Responses
X
Species
Rat
Chicken
Rat
Rat
Rat
Chicken
Mouse
Rat
Rat
Goat
Rat
Mouse
Rat
Mouse
Age
Embryo
Embryo
Fetal
Embryo-fetal
Embryo-fetal
Embryo
Adult
Embryo-fetal
Embryo-fetal
Adult
Adult
Adult
Neonatal/ Juvenile
Adult
Strain/Gender
SD females
Cornell K females
CD females
F344 and CD females
F344 females
Cornell K females
BALB/c females
F344 females
F344 females
Females
Wistar males
Swiss
CD females
BALB/c
Route
Oral to Dam
in ovo
Oral to Dam
Oral to Dam
Oral to Dam
in ovo
Oral
Oral to Dam
Oral to Dam
Gastric intubation
Oral
s.c.
Oral
i.p.
Lowest Effective Dose
250 ppm (BLL at 4 wk = 6.75 Ug/dL)
200 ug
500 ppm
250 ppm
250 ppm (BLL = 34.8ug/dL at birth)
200 ug (BLL =11 ug/dL)
512 ppm (BLL = 87 Ug/dL)
250 ppm Pb acetate
250 ppm Pb acetate
50 mg/kg Pb acetate
6.3 mmol kg "'
0.5 mg/kg/d
25 ppm Pb acetate (BLL= 29.3 Ug/dL)
0.025 mg Pb acetate
Duration
of Exposure
5 wks
Single injection E12
6 days
3 wks
3 wks
Single injection E12
3 wks
5 wks (2 before, 3
during gestation)
5 wks (2 before, 3
during gestation)
6 wks
8 wks
Shortest = 3 days
just prior to
challenge
6 wks
30 days
Reference
Chen et al. (2004)
Lee et al. (2002)
Bunn et al.
(200 Ic)
Bunn et al.
(200 Ib)
Bunn et al.
(200 la)
Leeetal. (2001)
McCabe et al.
(1999)
Chen et al. (1999)
Miller et al.
(1998)
Haneef et al.
(1995)
Kumar et al.
(1994)
Laschi-Loquerie
et al. (1984)
Faith et al. (1979)
Muller et al.
(1977)
-------
Table AX5-9.4. Effect of Lead on Allogeneic and Syngeneic Mixed Lymphocyte Responses
Species
Mouse
Rat
Mouse
Mouse
Mouse
Strain/Gender
C57B1/6 and
BALB/c
Lewis males
CBA/J females
CBA/J females
DBA/2J males
Age
Adult
Adult
Adult
Adult
Adult
Proliferation
Effects
fAllo-MLR
fAllo-MLR
fSyngeneic-MLR
fAllo-MLR
fAllo-MLR
Allo-MLR no
significant change
In Vivo/
Ex Vivo
No
No
No
Yes
Yes
Lead Dose/Concentration
0.1 |iM
50 ppm Pb acetate
10~6-10~4M
0.08 mM and 0.4 mM
13, 130 and 1300 ppm
Duration
of Exposure
4 days
4 days
5 days
4 wks
lOwks
References
McCabeetal. (2001)
Razani-Boroujerdi et al.
(1999)
Lawrence (1 98 Ib)
Lawrence (1981a)
Roller and Roan (1980)
X
to
-------
Table AX5-9.5. Effect of Lead on Mitogen-induced Lymphoid Proliferation
X
Species
Human
Mouse
Mouse
Rat
Mouse
Rat
Mouse
Mouse
Rat
Mouse
Mouse
Mouse
Strain/ Gender Age
- Adult
TO males Adult
Several Adult
Lewis and F344 Adult
males
CBA/J Adult
AP strain males Adult
CBA/J females Adult
BDF1 females Adult
SD males Adult
CBA/J females Adult
CBA/J females Adult
CBA/J females Adult
In Vivo/
Proliferation Effects Ex Vivo Lead Dose/ Concentration
|PHA Yes Not available
4 ConA Yes 1 mg/kg daily
|LPS
PHA stimulation No No 25 uM
change
|ConA No 25 ppm
TLPS
LPS No change No 10 uM
PHA No change Yes 100 ppm and 1,000 ppm
ConA No 10~4 M
LPS
No change
TConA Yes 0-1,000 ppm
|PHA
fStaph A enterotoxin
LPS no change
|ConA Yes 1% Pb acetate in diet
TPHA
|LPS
PHA no change Yes 10 mM
|LPS (high doses only)
ConA, PHA no change No io~6-10~4 M
|LPS
ConA, PHA no change No 10~6-10~4 M
|LPS
Duration
of Exposure
Occupational
2 wks
3 days
3 days
3 days
2-20 wks
2 days
3 wks
2 wks
4 wks
2.5 days
2-5 days
References
Mishra et al. (2003)
Fernandez-Carbezudo et al.
(2003)
McCabeetal. (2001)
Razani-Boroujerdi et al. (1999)
McCabe and Lawrence (1990)
Kimber et al. (1986)
Warner and Lawrence (1986)
Blakley and Archer (1982)
Bendichetal. (1981)
Lawrence (1981a)
Lawrence (1981b)
Lawrence (1 98 Ic)
-------
Table AX5-9.5 (cont'd). Effect of Lead on Mitogen-induced Lymphoid Proliferation
X
Species
Mouse
Rat
Mouse
Mouse
Mouse
Mouse
Mouse
Strain/ Gender Age
C57 Bl/6 males Adult
SD females Neonatal-
Juveniles
BALB/c Adult
Swiss males Adult
Swiss males Adult
CBA/J Adult
BALB/c Adult
Proliferation Effects
|PHA
|ConA
LPS No change
|PHA
|ConA
TLPS
|PHA
|PWM
|PHA
|PWM
|LPS
|LPS
In Vivo/
Ex Vivo Lead Dose/ Concentration
Yes 1,300 ppm
Yes 25 ppm
No 10~5-10~3 M
Yes 2,000 ppm
No O.lmM-l.OmM
Yes 13 ppm
NO icr5-icr3M
Duration
of Exposure
8wks
6 wks
3 days
30 days
2-3 days
18 mo
2-3 days
References
Neilanetal. (1980)
Faith et al. (1979)
Gallagher et al. (1979)
Gaworski and Sharma (1978)
Gaworski and Sharma
(1978)
Roller etal. (1977)
Shenkeretal. (1977)
-------
Table AX5.9.6. Pattern of Lead-induced Macrophage Immunotoxicity
X
Species
Strain/
Gender
Age
Function
In Vivo/
Ex Vivo
Lowest Effective
Dose
Duration
of Exposure
References
Nitric Oxide
Human
Rat
Chicken
Mouse
Chicken
Mouse
Mouse
Reactive
Human
Rat
Mouse
Rabbit
Both genders
CD males
Cornell K
strain females
BALB/c
females
HD-llcell
line
CBA/J
females
CBA/J
females
Juvenile
Embryo
Embryo
Adult
-
Adult
Adult
|NO
|NO
|NO
|NO
|NO
|NO
|NO
Yes
Yes
Yes
No
No
No
No
NK
500 ppm
10 Hg
20 ng/mL
one lower dose tNO
4.5 jig
1.0 ng
0.625 iiM
6 days
One injection
(E5)
2hrs
18hrs
4 days
4 days
Pineda-Zavaleta et al.
(2004)
Bunnetal. (2001c)
Lee etal. (2001)
Krocova et al. (2000)
Chen etal. (1997b)
Tian and Lawrence (1996)
Tian and Lawrence (1995)
Oxygen Intermediates
Associated in
males
Not indicated
BALB/c
females
New Zealand
white males
Juvenile
NK
Adult
Adult
tROI
tROI
tROI
tROI
Yes
No
Yes
Yes
NK
240 |iM
1.5 mg/kg diet
31 |ig/m3 inhaled
NK
3hrs
30 days
3 days
Pineda-Zavaleta et al.
(2004)
Shabani and Rabbani
(2000)
Baykov etal. (1996)
Zelikoff etal. (1993)
-------
ANNEX TABLES AX5-10
AX5-156
-------
Table AX5-10.1. Hepatic Drug Metabolism
>
X
Concentration
Triethyl Pb
chloride, 0-3.0
mg/kg b. wt.
In vitro, 0.0-3.0
mM triethyl Pb
5 or 10 umol/lOOg
b. wt. Pb nitrate;
i.v.
5, 10, SOmgPb
acetate kg"1 b. wt.
100 umol/kg; i.v.
Pb acetate
100 umol/kg
Pb nitrate; i.v.
100 umol/kg; i.v.
Pb acetate
100 umoles/kg;
i.v.
Duration
2 days
Not specified
36 h
Multiple
durations
(15 days,
2 and 3 mo)
24 h
9 h before or 6 h
after
2-methoxy-4-
aminoazobenzene
(2-Meo-AAB)
24 h
Multiple
durations (3, 6,
12, 24, and 36 h)
Species
In vitro, rat
microsomes
In vivo, rat
microsomes
Male Fischer
344 rats
Female albino
rats
Male Fischer
344 rats
Male Fischer
344 rats
Male F 344 rats
Male Wistar
rats
Blood Lead Effects3
— Triethyl Pb increased microsomal N-oxygenation in vivo and
decreased microsomal C oxygenation by in vitro treatment. Either
treatment thus gave rise to an increase in the N-oxygenation/C-
oxygenation ratio, which may lead to tumor potentiation.
— Pb decreases phase I components (liver microsomal cyt.P-450), and
increases Phase II components (GST, DT diaphorase etc). Liver
cytosol in treated animals had a polypeptide that cross-reacted with
GSTP.
— Over all induction of cyt-p — 450 and b5 in liver, long-term increase
in liver GST and GSH.
— Decrease in total C YP amount, selective inhibition of CYP1A2 and
decrease in the expression at m-RNA and protein level, induction of
placental form of glutathione s-transferase (GST-P).
— Male fisher rats treated with different metal ions — Pb nitrate, nickel
chloride, cobalt chloride or cadmium chloride exhibited decreased
total CYP amount in liver microsomes. However, only Pb reduced
the levels of the mRNA and protein of CYP 1A2 induced with 2-
methoxy-4-aminoazobenzene (2-Meo-AAB) and decreased the
microsomal activity (Per CYP), Pb also induced placental form of
Glutathione, a marker enzyme for preneoplastic lesion.
— Inhibition of CYP1 A mRNA(s) by Pb nitrate is by aromatic amines,
not by aryl hydrocarbons.
— Stimulation of TNFa preceding hepatocyte DNA synthesis
indicates a role for it in liver cell proliferation.
Pb nitrate enhances sensitivity to bacterial LPS, in hepatocytes.
Reference
Odenbro and
Arhenius(1984)
Roomi et al.
(1986)
Nehru and
Kaushal(1992)
Degawa et al.
(1994)
Degawa et al.
(1995)
Degawa et al.
(1996)
Shinozuka et al.
(1994)
-------
Table AX5-10.1 (cont'd). Hepatic Drug Metabolism
>
X
Ni(II) > Cu(II) > Co(II) = Zn(II), Pb(II), Cd(II) and (Cu).
May affect Cypl A system of the fish liver at low concentrations
through the direct inhibition of CYP 1A enzyme activity.
— Pb acetate and nitrate induce DT diaphorase activity which is
inhibited significantly by Dil a calcium antagonist, showing that
these changes are mediated by intracellular calcium changes. Pb
acetate induces DT diaphorase activity with out thymus atrophy and
hence was suggested to be a monofunctional inducer as against the
Methyl cholanthrene induced DT diaphorase activity.
— The effect of metals on PAH induced CYP1A and 1A2 as probed
by Ethoxy resorufin o- deethylase activity has demonstrated, metals
-Arsenic, Pb, mercury and cadmium decreased CYP1 Al/ A2
expression by polycyclic aromatic hydrocarbons depending on the
dose, metal and the PAH. Arsenic was most effective, followed by
Pb, cadmium, and mercury. Cell viability was decreased by 20-
28% by metals.
Reference
Calabrese et al.
(1995)
Jover (1996)
Bruschweiler
etal. (1996)
Arizono et al.
(1996)
Vakharia(2001)
-------
Table AX5-10.1 (cont'd). Hepatic Drug Metabolism
>
X
Concentration
10-100 uM,
in vitro
5 and 10
umoles/100 g of
b.wt, single i.p
100 umoles/100 g
b. wt. Pb nitrate,
single injection, i.v.
100 mg/kg i.p.,
single exposure
100 umol/kg body
wt, i.v
100 umol/kg b. wt.,
intra cardiac
lOumol/lOOgb.
wt., Pb nitrate, i.v.
single dose
Duration
24 h
—
Animals were
sacrificed at
1,2, 3, 4, and
15 days
Multiple analyses
0-96 h
70 h
Multiple time
point analyses
starting 6 days to
5 mo
Analyses at
multiple time
points 0-10 days
Species
Murine
hepatoma cell
line
Wistar Rat
Wistar rats
Male DDY
strain mice
Male Sprague
Dawley rats
Male and
female Wistar
rats
Male Fischer
344 young adult
rats
Blood Lead Effects3
— Effect of heavy metals on Ary 1 hydrocarbon regulated genes —
metals alone did not induce a significant change in the cyplal
activity and protein levels but increased its m-RNA expression.
AHR ligand-mediated induction of cyplal activity and protein was
observed by all the metals. Pre and post translational modulation in
this regulation have been implicated. These results demonstrate
that the heavy metals differentially modulate the constitutive and
the inducible expression of AHR regulated genes.
— Pb nitrate induced the expression of Placenta! form of Glutathione
transferase along with liver cell proliferation. The biochemical
lesions induced by Pb under these conditions were similar to that of
hepatic nodules.
— Acute Pb treatment results in induced activity of Gamma-glutamyl
transpeptidase, induced GSTP, a typical marker of pre neoplastic
lesion in most hepatocytes. Pb also inhibited liver adenylate
cyclase activity 24 h postexposure.
— Pb decreased Glutathione content and decreased Glutathione s-
transf erase activity that is independent of Glutathione levels.
— Acute Pb nitrate treatment caused a significant increase of GST
activity in liver and kidney. While in liver the activity increase is
mainly due to isozyme GST 7-7, in kidney it is through the
induction of all the isozymes.
— Intracardiac administration of Pb acetate results in elevation of
glutathione transferase (GST) in Kupffer cells, the early response to
GST. Yp was observed in sinusoidal cells and had a later patchy
response in the expression of GST.Yp Yp in hepatocytes
— Glutathione transferase Pl-1 is induced significantly by a single
intravenous dose of Pb nitrate through increased transcription and
modulations at post transcription and translational levels.
Reference
Korashy and
El-Kadi (2004)
Roomi et al.
(1987)
Columbano et al.
(1988)
Nakagawa et al.
(1991)
Planas-Bhone and
Elizalde(1992)
Boyce and Mantel
(1993)
Kooetal. (1994)
-------
Table AX5-10.1 (cont'd). Hepatic Drug Metabolism
>
X
Concentration
Pb nitrate,
100 urn/kg i.p,
3 times every 24 h
Pb acetate
100 nM/kg.
lOnMPb nitrate
lOmgTriethylPb,
i.p. single dose
114mgPb
acetate/kg b. wt. i.p
A. 1.5-3.0mg/kg
wt
Triethyl Pb (TEL)
i.p.
B. 0.05-0.5, TEL
to liver microsomal
fractions
Duration
48 h
0.5-24 h
24 h before
transfection with
ECAT deletion
mutant, every 24
h there after till
48 h after
transfection
Analyses at
multiple durations
(3,4, 7, 10, or 14
days)
Single (0.5-12 h
group) or multiple
(72 h and 7 days
group) exposure
2 exposures for
48 h
30min
incubations
Species
Transgenic rats
with 5 different
constructs
having GST-P
and/or
chloromphenica
1 acetyl
transferase
coding
sequence.
NPJC Kidney
fibroblasts
Fischer 344 rats
Sprague Dawley
Female Wistar
Liver
microsomes
from female
Wistar rats
Blood Lead Effects3
— GSTP (placental GST), is regulated by Pb at transcriptional level.
GST-P enhancer (GPEI), is an essential cis-element required for the
activation of the GST-P gene by Pb and is involved in the activation
regardless of the trans-activators involved. GPEI element consists
of two AP-1 binding sites. Activation of GST-P gene by Pb is
mediated in major part by enhancer GPEI, which may involve AP-1
activation partially.
— Pb induces GST-P in NPJC normal rat kidney fibroblast cell line.
— Decreased liver Glutathione s-transferase (GST) activity and lower
levels of several hepatic GST.
Increase in quinone reductase activity by day 14 in liver.
— Pb exposure resulted in hepatic Glutathione (GSH) depletion and
increased malondialdehyde (MDA) production.
— Pretreatment of rats did not affect the liver microsomal Oestradiol-
l?p metabolism or the content of cytochrome P-450 and
cytochrome b5.
— TEL at 0.05 mM significantly reduced 17p-hydroxy steroid
oxidation and at concentration of 0.05 mM decreased 16a-
hydroxylation.
Reference
Suzuki et al.
(1996)
Daggett et al.
(1997)
Daggett et al.
(1998)
Odenbro and
Rafter (1988)
-------
Table AX5-10.1 (cont'd). Hepatic Drug Metabolism
Concentration
Duration
Species
Blood Lead
Effects3
Reference
50 mg/kg,
intragastric
! wks
Male Albino
Wistar rats
Accentuation of liver membrane lipid peroxidation. significant Sandhir and Gill
inhibition of liver antioxidant enzymes. Reduced ratio of reduced (1995)
glutathione(GSH) to oxidized glutathione (GSSG),
X
Abbreviations
b. wt.—body weight
aCYP—Cytochrome P-450
GSH—Glutathione
GSSG—Oxidized glutathione
TEL—Triethyl lead
CCL—Carbon tetrachloride
GSTP—Placental glutathione transferase
MDA—Malondialdehyde
Cu—Copper
Cd—Cadmium
Al—Aluminum
Zn—Zinc
Pb—Lead
Ni—Nickel
TNFa—Tumor necrosis factor
ALA—Alanine aminotransferase
PAH—Polycyclic aromatic hydrocarbons
LPS—Lipopolysaccharides
-------
Table AX5-10.2. Biochemical and Molecular Perturbations in Lead-induced Liver Tissue
>
X
to
Concentration Duration
Pb-diethyl 0.5-20 h
dithiocarbomate
complex, Pb (DTC) 2,
or Pb acetate 0.033-
10 uM
Species Blood Lead Effects"
Primary hepatocytes — Effect of interactions between Pb and diethyl dithiocarbomate (DTC) on the
enzyme 8 amino levulinic acid dehydratase in primary hepatocytes.
Lipophilic Pb (DTC)2 caused a more rapid and stronger inhibition of ALAD
activity than Pb acetate. Pb uptake is higher and more rapid with Pb (DTC)
2 than Pb acetate. This increased inhibition of ALAD activity by Pb (DTC)
2 might be due to facilitated cellular transport in the complexed form
resulting in higher cellular concentrations of Pb.
Primary rat — DTC decreases cellular effects of Pb and Cd despite unchanged/ even
hepatocytes slightly increased concentrations of the metals. Hepatic ALAD was
significantly inhibited in cells treated with Pb Ac and Pb (DTC)2.
DBA and C57 mice — DBA mice(with a duplication of the ALAD gene accumulated twice the
amount of Pb in their blood and had higher Pb levels in liver and kidney
than mice with the single copy of the gene (C57), exposed to the same oral
doses of the Pb during adult hood. Blood Zinc protoporphyrin (ZPP)
increased with Pb exposure in C57 mice and were not affected in DBA
mice.
Reference
Oskarsson and
Hellstrom-Lindahl
(1989)
Hellstrom-Lindahl
and Oskarsson
(1990)
Claudio et al.
(1997)
100 umol/kg b. wt. Single dose, Male Wistar Albino
i.v. single dose analyses performed Rats
12, 24, 48, 72, 96
and 168 h
Pb nitrate, Single dose 0-168 h
100 umol/kgb. wt.
Pb nitrate
Male Wistar rats
Wistar rats
First in vivo report showing association between Pb induced liver Dessi et al. (1984)
hyperplasia, Glucose-6-phosphate levels, and cholesterol synthesis.
Pb treatment increased hepatic de novo synthesis of cholesterol as evident
by increased cholesterol esters and increase of G-6-PD to possibly supply
the reduced equivalents for de novo synthesis of cholesterol. Changes in
these biochemical parameters were accompanied by liver hyperplasia.
Pb nitrate induces hepatic cell proliferation followed by reabsorption of Pani et al. (1984)
excess tissue with in 10-14 days. The proliferation was correlated with
hepatic denovo synthesis of cholesterol, stimulation of hexose
monophosphate shunt pathway and alterations in serum lipo proteins.
Pb nitrate induces multiple molecular forms of Glucose-6- phosphate Batetta et al. (1990)
dehydrogenase with an increase of band 3 and a concomitant increase of
band 1, shifting from the pattern induced by fasting with an increase in
band 1.
-------
Table AX5-10.2 (cont'd). Biochemical and Molecular Perturbations in Lead-induced Liver Tissue
Concentration
Duration
Species
Blood Lead
Effects"
Reference
>
X
Pb nitrate, single i.v.
10uM/100gb. wt.
Multiple time points Male Wistar rats
24-72 h and
20 days
Pb nitrate exposure results in complete loss of liver glycogen between 24
and 48 h, which was replenished and was found in excess in treated liver
hepatocytes by 20 days. Glycogen synthase and glycogen phosphorylase
activities were diminished by 24 h and return to normal values by day 20.
The pentose phosphate enzymes were upregulated, which coincided highly
with the increase in mitotic rate. Overall Pb nitrate induces drastic
alterations in hepatic carbohydrate metabolism along with increased hepatic
cell proliferation.
Hacker et al. (1990)
10 or 20 mg/kg as Pb Once a wk for
acetate, subcutaneous 5 wks
100 uM/kgb. wt Pb 36 h postexposure
nitrate, i.v
2000 ppm Pb acetate 3 wks
in diet.
O^tOOOppm 21 days
Pb acetate, oral
Rats
Occupationally
exposed workers
Rats
Male Wistar Albino
rats
Arbor Acres male
chicks
Arbor Acre broiler
chicks
Pb-exposed
workers:
0.24-30 nM/mL
Control rats:
0.1 8 nM/mL
10 mg Pb/kg:
2.42 nM/mL:
20 mg Pb/kg:
3.82 nM/mL
—
—
—
Pb acetate induced mitotic response much more effectively in renal
epithelial cells than liver cells (675 fold less).
Pb induces lipid peroxidation in serum of manual workers, while blood
superoxide dismutase (SOD) activity decreased. Similar phenomenon was
observed with rats that were subcutaneously injected with Pb acetate.
At higher than 20 uM concentration, Pb in untreated microsomes increased
NADPH dependent lipid peroxidation.
Endogenous source of newly synthesized cholesterol together with increase
of HMP shunt enzyme activities is essential for hepatic cell proliferation by
Pb nitrate.
Liver non protein sulphahydryl (NPSH) and glutathione (GSH) were
increased upon Pb exposure. The concentrations of liver glutamate, glycine,
and methionine were also elevated upon Pb exposure.
Pb increases tissue peroxidation via a relative increase of 20:4 fatty acids.
Decrease in the hepatic ratio of 18:2/20:4 might be specific to Pb toxicity.
Calabrese and
Baldwin et al.
(1992)
Ito et al. (1985)
Dessi et al. (1990)
Me Gowan and
Donaldson et al.
(1987)
Donald and
Leeming (1984)
-------
Table AX5-10.2 (cont'd). Biochemical and Molecular Perturbations in Lead-induced Liver Tissue
>
X
Concentration Duration
Sodium vanadate, Acute studies,
30 mg/kg 24 h
subcutaneous in mice
30 mg/kg b.wt, i.p. in
rats
0.5 mM
Vanadium sulphate in Chronic studies
drinking water for lOwks
chronic treatment
250-2000 ppm Pb 19 days
acetate in diet
1.25-20.00 mg/LPb 30 days
nitrate, oral
250 mg/L of Pb as Pb 5 wks of exposure
acetate, oral followed by 4 wks
of recovery
35-70 mg, Pb intra One or two times a
gastric wk/7 wks
Species Blood Lead
Male Swiss- —
Webster mice
Male Sprague
Dawley Rat
—
Arbor Acre broiler —
chicks
Fresh water fish —
Weanling female —
SD rats
Male Buffalo rats Control: 4.6 ug/dL
Pb 35 mg/kg:
16.8 ug/dL
Pb 70 mg/kg:
32.4 ug/dL
Effects"
Sodium orthovandate increases lipid peroxidation in kidneys of mice and
rats. Malondialdehyde (MDA) formation increased 100%, with in 1 h
after injection.
In both rat and mice, no significant increase in lipid peroxidation was
observed in brain, heart, lung, and spleen.
Chronic exposure to vanadium, through maternal milk and drinking water
for 10 wks increased MDA formation and lipid peroxidation in kidneys.
Dietary Pb consistently increased liver arachidonic acid, the
arachidonate/linoleate ratio and hepatic non-protein sulfhydryl
concentration. Hepatic microsomal fatty acid elongation activity was
decreased by Pb over all. These results demonstrate that changes in the
precursors and mechanisms involved with eicosanoid metabolism are not
always reflected in tissue concentrations of leukotriens and prostaglandin.
Pb accumulation in the liver and other tissue increased in a dose dependent
manner up to 5mg/L, exposure to sublethal concentration (5 ppm) of Pb
reduced the total lipids, phospholipids, and cholesterol levels in the liver
and ovary. Pb nitrate may affect the fecundity of fish by altered lipid
metabolism.
Effect of weight loss on body burden of Pb: weight loss increases the
quantity and concentration of Pb in the liver even in the absence of
continued exposure.
Decrease in plasma cholesterol, and HDL fraction, increase in serum
triglyceride, atrophy of the elastic fibers in the aorta.
Reference
Donaldson et al.
(1985)
Knowles and
Donaldson et al.
(1990)
Tulasi et al. (1992)
Han et al. (1996)
Skoczynska et al.
(1993)
Abbreviations
aCYP—Cytochrome P-450
ALAD—Aminolevulinic acid dehydratas
GSH—Reduced Glutathione
ZPP—Zinc protoporphyrin
HMP—Hexose monophosphate shunt pathway
b. wt.—body weight
-------
Table AX5-10.3. Effect of Lead Exposure on Hepatic Cholesterol Metabolism
>
X
Concentration
100 (imol/kg body wt,
i.v. Pb nitrate
100 umol/kg body wt,
i.v. Pb nitrate
0.05 mg/kg body
wt/d. Pb acetate,
subcutaneous, with or
Duration
Multiple durations
0, 3, 6, 12, 24, and
48 h
Multiple durations
0, 1,3,6, 12, 18,24,
48, and 72 h
Preexposure for
5-7 days, gestation
through lactation
Species
Male Sprague
Dwaley (SD) rats
Male Sprague
Dawley (SD) rats
Female Charles
Foster rats
Blood Lead Effects"
— Pb nitrate, activates the expression of the SREBP-2 and CYP 5 1 gene
with out decreasing the serum cholesterol level.
— Pb nitrate effects on hepatic enzymes involved in cholesterol homeostasis.
Demonstrated for the first time sterol independent gene regulation of
cholesterol synthesis in Pb nitrate treatment.
— Pb and cadmium accumulated in the livers of metal treated pregnant and
lactating rats. Hepatic steroid metabolizing enzyme 17-p-hydroxy steroid
oxidoreductase and UDP glucaronyl transferase were decreased and the
Reference
Kojima et al. (2002)
Kojima et al. (2004)
Pillai and Gupta
(2004)
without cadmium
acetate 0.025 mg Pb
acetate/kg body wt/d
hepatic Cytochrome P-450 content was reduced by the metal exposure.
Pb and cadmium alter liver biochemical parameters, however, combined
exposure had no intensifying effect on liver parameters. When
administered together on similar concentration basis, the major effects
are mediated by cadmium.
300 mg/L Pb acetate,
oral
Gestation through Female Wistar
lactation analyses rats
done at day 12 and
day 2 1 postnatal
Control: 1.13 ug/dL
Pb-exposed
12 days PN: 22.01
ug/dL
21dPN: 22.77 ug/dL
In neonates, decrease in liver Hb, iron, alkaline and acid phosphatase
levels. Protein, DNA and lipid total amounts were reduced and hepatic
glycogen content was reduced. Pb intoxication of mothers in gestation
and lactation results in alterations in the hepatic system in neonates
and pups.
Corpas et al.
(2002b)
a CYP—Cytochrome P-450
b wt.—body weight
-------
Table AX5-10.4. Lead, Oxidative Stress, and Chelation Therapy
>
X
Concentration and
Compound Duration
Pb acetate, 50 mg/kg 8 wks
b.wt, intragastric
2,000 ppm, Pb 5 wks
acetate, Diet
0.1-1.0 uM
Species
Male Albino
Wistar rats
Male Fisher 344
rats, young and
old
Rat liver
hepatocytes.
Normal and LAN
loaded
Blood Lead
—
Young control:
<1 ug/dL
Young Pb-exposed:
38.8 ug/dL
Old control:
<1 ug/dL
Old Pb-exposed:
2 1.7 ug/dL
—
Effects Reference
Pb induces accentuation of membrane lipid peroxidation in liver by the Sandir and Gill
changes (decrease) in the activities of several antioxidant enzymes such as (1995)
SOD, Catalase, GPx and Glutathione reductase. Pb exposure also caused
a reduction in GSH/GSSG ratio (reduced to oxidized Glutathione).
Effect of Pb on lipid peroxidation in young vs. adult rats- Liver GSSG and Aykin-Burns et al.
malondialdehydehyde levels were significantly higher in young rats than (2003)
adult rats. Blood Pb levels were higher in young exposed animals as
compared to adults. In young, Pb exposed animals, Pb induced oxidative
stress was more pronounced particularly in liver tissue.
Lipid peroxidation as indicated by Malondialdehyde accumulation Furono et al. (1996)
upon exposure to various redox-sensitive metals in cultured rat
hepatocytes and hepatocytes loaded with a-linolenic acid indicated that
Al, Cr and Manganese, Ni, Pb and tin did not effectively induce lipid
peroxidation in these cells.
- The induction was the highest in ferrous iron treated cells compared
to other metals (Cu, Cd, V, Ni).
FeSO4, VC13, CuSO4,
CdCl2, CoCl2, A1C13,
CrCl3, MnCl2, NiSO4,
Pb(NO3)2, SnCl2,
culture medium
9h
LAN—bovine serum
complex 0.8 mM in
culture medium
Additional 12 h
incubation
With any metal, the induction was higher in a-linolenic acid treated cells.
Iron and V induced cell injury in LAN loaded cells was prevented by
addition of DPPD. Cd was a weak inducer of lipid peroxidation under
these conditions.
5 mg kg-1, Pb
acetate, i.p., single
dose followed by
therapy with chelating
agents
Analyses after
6 days of treatment
DMSA, Mi-
ADMSA at multiple
times (0.5, 24 hr,
4th and 5th day
after Pb treat
Wistar 6 days old
suckling rats
— Treatment with DMSA and Mi- ADMSA showed Mi-ADMS A to be
more effective in reducing the skeletal, kidney and brain content of Pb.
However there was no difference in reducing the liver Pb content
between the two compounds.
Blanusa et al.
(1995)
-------
Table AX5-10.4 (cont'd). Lead, Oxidative Stress, and Chelation Therapy
>
X
Concentration and
Compound
550 ppm Pb acetate,
oral DMSA treatment.
Pb acetate Dose to
achieve blood Pb
levels of 3 5-
40 ug/dL.
Biweekly dose
adjustments, oral
followed by treatment
with chelator.
5 mg Pb kg-1, i.p Pb
acetate followed by
chelators for various
time points.
Duration Species Blood Lead
(A) Pb for 35+ 6-7 Wk old male Pb-exposed:
21 days Sprague-Dawley 50 ug/dL
(B) Pb 35 days and rats Pb 35 days: Ranged
Pb and DMSA from 5-20 ug/dL +
for 21 days DMSA from 0-
240 Lig/kg/d
(C) Pb 35 days and
DMSA for
21 days
(D) Acedified Di H2O
for 35 days and
Di water for
21 days
1 yr, chelator for Infant rhesus Pb-exposed:
two successive monkeys 35-40 ug/dL
19 day period
following Pb
exposure.
Analyses at Day 5 Suckling Wistar —
rats
Effects
DMSA reversed the hematological effects of Pb, decreased the blood,
brain , bone, kidney and liver concentration and produced marked Pb
diuresis, even when challenged with ongoing Pb exposure.
Specific emphasis on the beneficial effects of succimer treatment to
cessation of Pb exposure. These data demonstrated that succimer
efficiently reduces blood Pb levels which does not persist beyond the
completion of treatment. They also demonstrate the relative benefit of
eliminating Pb exposures , which serves to underscore the importance of
primary prevention of Pb exposure. Neither DMSA treatment nor the
cessation of Pb exposure were beneficial in reducing skeletal Pb levels.
Meso — DMSA is the treatment of choice for acute Pb poisoning in infants
compared to EDTA and Rac-DMSA.
Reference
Pappasetal. (1995)
Smith et al. (2000)
Kostialetal. (1999)
50 mg/kg Pb as Pb 24 h
nitrate, i.p, two
injections, 16h apart
50% Ethanol, 0.5 mL,
two injections, 16 h
apart
0.1% Pb acetate in 4 wks
drinking water with
and without Sodium
Molybdate, i.p
Male Albino rats
Male Albino rats
Pb-exposed:
39 ug/dL
Pb + chelators:
4.6-13.1 ug/dL
S-Adenosyl methionine confers protection against alterations in several Flora and Seth
parameters (ALAD, GSH, MDA) indicative of lipid peroxidation in blood, (1999)
liver and brain in Pb and acute Pb and ethanol exposed animals as well as
the organ concentration of Pb.
Sodium molybdate significantly protected the uptake of Pb in blood, liver Flora et al. (1993)
and kidney. The treatment with molybdate also restored the Pb induced
inhibited activity of blood 8-aminolevulinic acid dehydratase and the
elevation of blood Zn protoporphyrin , hepatic lipid peroxidation and
serum ceruloplasmin.
-------
Table AX5-10.4 (cont'd). Lead, Oxidative Stress, and Chelation Therapy
>
X
-------
Table AX5-10.4 (cont'd). Lead, Oxidative Stress, and Chelation Therapy
>
X
Concentration and
Compound
0-500 uM Pb acetate
2000ppmofPb
acetate in drinking
water for 5 wks
Taurine
l.lkg/d
1 mg Pb2+/kg B.wt ,
i.p. Pb acetate
Pb as acetate, 400 mg
Pb2+/mL, drinking
water
0.5 mg/mL
L-methionine
100 uM/kg b.wt. Pb
acetate,
intramuscular, single
Duration
6h
5 wks
6th wk
4 wks, treatment
with various
antioxidant in the
5th wk
10 days
4 wks post-Pb
exposure
3 and 24 h
Species Blood Lead Effects
CHO cells and — Antioxidant Taurine reversed the abnormalities associated with lipid
peroxidation parameters such as increased. Malondialdehyde formation
Fischer 344 rats Controls: 0.43 ug/dL and decreased Glutathione and enhanced CHO cell survival. However,
Pb excosed' was no* effective 'n reducing cell and tissue Pb burden in CHO cells and
36.4 ug/dL Pb exP°sed Fischer rats.
Pb + Taurine:
33.8 ug/dL
IVRI 2 CQ rats — Pb exposure resulted in increased lipid peroxidation, with tissue specific
changes in liver. Treatment of exposed rats with ascorbic acid and a-
tocopherol lowered the lipid peroxidation.
Kunming mice — L- methionine has an ameliorative effect on Pb toxicity-Methionine
reduced the decrease in Hb content and depressed body growth caused by
Pb. Treatment with dietary methione along with Pb decreased the MDA
formation as opposed to Pb, moderately reversed the decreased iron
content of the organs and decreased organ Pb content.
Male Albino rats — Pb exposure resulted in significant increases in acid and alkaline
phosphatases, serum GOT and GPT, elevated liver and kidney lipid
peroxidation and decreased antioxidant enzymes at 3 and 24 h after
Reference
Gureretal. (2001)
Patraetal. (2001)
Xie et al. (2003)
Othman and El
Missiry (1998)
100 jig/ Pb acetate,
intra gastric, oral and
intraperitoneal,
treated with or with
out thiamin (25,
50 mg/kg b.wt) and or
Ca EDTA (50 mg/kg
B.wt
3 days
CD-I mice
exposure. Selenium administration prior to Pb exposure produced
pronounced prophylactic effects against Pb exposure by enhancing
endogenous anti oxidant capacity.
Two times more whole body Pb was retained by intraperitoneal injection
as compared to intragastric administration. Thiamin treatment increased
the whole body retention of both intragastric and intraperitoneal Pb by
about 10%. Calcium EDTA either alone or in combination with thiamin
reduced the whole body retention of Pb by about 14% regardless of the
route of exposure. Regardless of the route Ca EDTA in the combined
treatment reduced the relative retention of Pb in both in liver and kidney.
These studies indicate the combination treatment with thiamin and Ca
EDTA alters the distribution and retention of Pb in a manner which might
have therapeutic application.
Kim et al. (1992)
-------
Table AX5-10.4 (cont'd). Lead, Oxidative Stress, and Chelation Therapy
X
Concentration and
Compound
2000 ppm Pb acetate,
oral
I chelators
LA, DMSA,
MiADMSA
LA + DMSA + LA+
MiADMSA
0.1% Pb as acetate in
drinking water
DMSA — 50 mg/kg,
i.p./d
MiADMSA— 50
mg/kg, i.p./d
Vitamin E 5 mg/kg
and vitamin C
25 mg/kg/d, i.v. and
oral
500 mg/kg Pb acetate
daily, oral treatment
with chelators
Pb as acetate 0.2% in
drinking water
LA 25 mg/kg b.wt and
DMSA 20 mg/kg b.wt
Duration Species
4 wks, 5 days of Male Wistar
treatment with albino rats
antioxidant or
chelators
3 mo Male Wistar rats
5 days post-Pb
exposure
Multiple durations Male Albino rats
(2, 4, and 6 wks)
5 wks followed by Male Albino rats
a 6th wk
administration of
LA and or DMSA
Blood Lead Effects Reference
Normal: 1.42 ug/dL Treatment with all the chelators reduced hepatic GSH and reduced GSSG Pande and Flora
Pb: 40.93 ug/dL levels. Significant beneficial role of Alpha-lipoic acid (LA), in recovering (2002)
Pb + chelators: 38.5- the altered biochemical parameters, however showed no chelating
4.27 ug/dL properties in lessening body Pb burden either from blood, liver, or kidney.
Most beneficial effects against Pb poisoning was observed with combined
treatment of lipoic acid and either DMSA (meso 2,3-dimercaptosuccinic
acid) or MiADMSA (Mono isoamyl DMSA).
— Single or combined administration of vitamin C, a-tocopherol and the Flora et al. (2003)
chelators DMSA and Mi ADMSA against the Parameters of Pb induced
oxidative stress- thiol chelators and the vitamins could bring the blood
ALAD to normal levels, most significantly by combined administration of
Mi ADMSA with vitamin C. Vitamin C and E were effective against
reducing oxidized glutathione ( GSSG), and thibarbituric acid reactive
substance(TBARS) and increasing catalase activity. MiADMSA and
DMSA with vitamin C were effective in increasing hepatic GSH levels.
In summary combined treatment regimens with thiol chelators and
vitamins seem very effective in reducing the Pb induced oxidative stress.
Control: 0.32 ug/dL Impact of combined administration of vitamin C and Sylimarin on Pb Shalan et al. (2005)
Pb-exposed: toxicity. Combined treatment of Pb-exposed animals with vitamin C and
0.48-0.56 ug/dL Silymarin showed marked improvement of the adverse biochemical,
Pb + chelators: molecular and histopathological signs associated with Pb toxicity.
0.32-0.36 ug/dL
— Pb treatment for 5 wks resulted hepatic enzymes alanine transaminase, Sivaprasad et al.
aspartate transaminase, and alkaline phosphatase, increased lipid (2004)
peroxidation, and decreased hepatic anti oxidant enzymes. LA or DMSA
alone, partially abrogated these effects, however, in combination
completely reversed the lipid oxidative damage.
Abbreviations
b. wt.—body weight
aCYP—Cytochrome P-450
SOD—Super oxide dismutase
GSH—Glutathione
GSH/GSSG Ratio—Reduced Glutathione/Oxidized Glutathione
MDA—Malondialdehyde
Al—Aluminum
As—Arsenic
MiDMSA—Mi monoisoamyl DMSA
Cr—Cromium
V—Vanadium
Pb—Lead
NAC—N acetyl cysteine
FeSO4—Ferrous sulphate
A1C13—Aluminum chloride
VC13—Vanadium chloride
CdCl2-—Cadmium chloride
CuSO4—Copper sulphate
CrCl3—Cromium chloride
MnCl2—Manganese chloride
NiSO4—Nickel sulphate
CoCl2—Cobalt chloride
LAN—a Linolenic acid
DPPD—DPPDJV-JV Diphenyl -p-phynylene-diamine
LA—Lipoic acid
DMSA—Monoisoamyl DMSA
-------
Table AX5-10.5. Lead-induced Liver Hyperplasia: Mediators and Molecular Mechanisms
Concentration
Duration
Species
Blood Lead
Effects"
Reference
Rat
>
X
A. Pb nitrate,
100 uM/kg b.wt,
intra-gastric
B. Diethyl
nitrosoamine
200 mg/kg b.wt, i.p.
0-100 uM Pb
sulphate, Pb
monoxide, Pb
chloride and Pb
acetate up to 1 mM,
culture media.
Choline Ig/kg/d in
drinking water
3 and 15 days
Male Wistar
Albino rats
Multiple time points REL liver cells
ranging from 24 h
up to 7 days
0, 20, and 24 h
Male and female
rats , partial
hepatectomy
Pb nitrate, 75 uM/kg
b.wt, single i.v.
75 umol/kg b. wt. Pb
nitrate in adult and 20
ug/mL in the young,
i.v.; single dose
6 h-4 wks
Adult male Albino
rats
Analyses at 72 h Male Wistar
Albino rats
Apoptosis plays a major role in the regressive phase of Pb nitrate induced
hepatic hyperplasia as detected by the apoptotic bodies by in situ end
labeling and HandE sections of the hepatic tissue. HandE scores mostly
cells in apoptosis phase II, ISEL (in situ end labeling) scores for cells in
phase I. Combination of these two methods is suggested for the better
understanding of the extent and nature of apoptotic process in liver cells
treated with chemicals.
Mitogenic stimuli (3 days Pb nitrate treatment) and complete regression
(15 days after the treatment), affected the apoptosis differentially.
Influence of apoptosis Vs necrosis on the growth of hepatocytes initiated
by diethyl nitrosamine followed by Pb nitrate treatment indicated that the
regenerative response elicited by a necrogenic dose of CCL4 promoted
GSTP (Placental glutathione), a pre-neoplastic marker positive cells as
against the Pb nitrate that induced the apoptosis.
Pb compounds showed a dose and time related effect on REL liver cell
proliferation with varying potencies specific to the different Pb salts.
Pb acetate was the most effective and Pb monoxide, the least effective.
On 1 hr treatment none of the compounds tested affected the intracellular
communication.
PKC isozymes during liver cell regeneration— PKC 8 showed a
pronounced increase 20h after partial hepatectomy. a, p, and Zeta at 24 h
corresponding with S-phase. Sexual dimorphism matching with sexual
differences in DNA synthesis was evident. Administration of choline was
able to modulate the protein kinase C isozyme pattern in females in
relation to DNA synthesis and c-myc expression. Taken together the data
positively implicates a, p, and Zeta in growth after partial hepatectomy
and 8 in negative regulation.
Pb induced significant increase in liver weight. Increased 3H Thymidine
incorporation. Pb induces extensive hypomethylation in treated rat livers.
Site-specific effect on methylation was confirmed at Hpa II, Msp I,
Hae III.
Effect of Pb nitrate on the 5- methyl deoxy cytidine (5-mdcyd) content and
the Hpall, MSPI, Hae III restriction patterns of hepatic DNA from young,
middle aged and senescent rats. The results indicated that the methylation
pattern of genomic DNA changed significantly with age and the
methylation patterns were differentially affected in all the three
populations.
Nakajima et al.
(1995)
Columbano et al.
(1996)
Apostoli et al.
(2000)
Tessitore et al.
(1995)
Kanducetal. (1991)
Kanduc and Frisco
(1992)
-------
Table AX5-10.5 (cont'd). Lead-induced Liver Hyperplasia: Mediators and Molecular Mechanisms
Concentration
10 umol/lOOgbody
weight Pb nitrate, i.v.
Duration
Multiple analyses
up to 40 h
Species
Male Wistar rats,
hepatocytes
from partial
hepatectomy and
Pb nitrate
treatment.
Blood Level Effects"
— The kinetics of DNA synthesis and expression of Proto oncogenes in
partially hepatectamized liver cells and Pb nitrate treated hepatic cells
indicated peak DNA synthesis after 24 h in the formal and after 36 h in the
later case. Both proliferative stimuli induced c-fos, c-myc and c-Ha Ras
expression. Induced c-myc expression persisted for up to 40h during the
Pb nitrate- induced liver cell proliferation. Pb induces hepatic hyperplasia
through changes in proto-oncogene expression.
Reference
Coni et al. (1989)
100 umol/kg, b. wt.
Pb nitrate, i.v.
>
X
Analyses at multiple
time points,
0.25-24 h
Male Wistar
Albino rats
Proliferative stimuli by means of Pb nitrate exposure resulted in increased
expression of c-jun m-RNA where as compensatory regeneration in
partially hepatectamized cells occurred through increased expression of c-
fos and c-jun. Different mitogenic stimuli induced differential expression
of these protooncogenes, in addition had a different profile than cells from
partial hepatectomy despite the cell cycle timings being the same in some
Coni et al. (1993)
to
100 umol/kgb. wt.
8h
100 umol/kg b. wt,
i.v.
100 umol/kgb. wt.,
i.v. Pb nitrate
Multiple analyses
time points,
1-120h
Analyses at multiple
time points, 8 h to
15 days
Male Sprague
Dawley rats
Male Wistar rats
Male Wistar rats
In rat liver, in addition to a few hepatocytes four types of non parenchymal Rijhsinghani et al.
cells namely, fibroblasts, macrophages, bile ducts and periductular cells (1992)
proliferate in response to Pb nitrate treatment. This growth is not related
to adaptive response secondary to parenchymal enlargement. However,
such growth in parenchymal cells seems dormant and does not play a
functional role in adult liver epithelial growth.
Both mRNA levels and enzyme activity of DNA polymerase p markedly Menegazzi et al.
increased before and/or during DNA synthesis in proliferating hepatocytes (1992)
in Pb nitrate treated and partially hepatectomized rats. 5 fold increase in
the enzyme activity was observed 8 h after Pb nitrate administration. In
the regenerative liver cells a 3 fold increase was observed 24-48h after
partial hepatectomy.
Pb nitrate induced Poly (ADP-ribose) polymerase mRNA 24 hr after Menegazzi et al.
exposure. A 2 fold increase in the mRNA levels of the enzyme occurred (1990)
2 days after the exposure. Such changes were also observed in hepatic
cells from livers of partial hepatectomy. These changes preceded the
increase in DNA synthesis and remained high during the time of extensive
DNA synthesis.
-------
Table AX5-10.5 (cont'd). Lead-induced Liver Hyperplasia: Mediators and Molecular Mechanisms
>
X
Concentration
30 mg/kg b. wt.
Pb nitrate
30 mg/kg b. wt.
Pb nitrate
100 umol/kgb. wt.
Pb nitrate, i.v., single
dose.
A. Mitosis —
Pb nitrate
100 uM/kg, i.v.
Ethylene
dibromide
100 mg/kg , intra
gastric
Cyproterone
acetate, 60 mg/kg
intra gastric.
B. Hepatocyte
nodules diethyl
nitrosamine
200 mg/kg
Pb nitrate, single i.v.
100 urn/kg b.wt
LPS— 12.5 ug/rat,
post Pb nitrate
treatment.
Duration Species Blood Lead
Multiple time points Adult male and —
up to 8 days female rats
Multiple time point Adult male and —
up to 60 h female rats
Multiple time point Male Wistar rats Serum Pb
analyses ranging concentrations
from 12-168 h peaking to 50-
60 ug/dL between
12-24 hand
remaining up to
40 ug/dLupto 108h
30-3 h Adult male Wistar —
rats
Multiple analyses at Male Wistar rats —
3, 6, 12, 24, and
36 h
Effects"
Pb nitrate induced liver hyperplasia exhibited sexual dimorphism where
mitogenic action was less effective and was delayed in females as
compared with males. Pre administration with choline partially filled
these sexual differences.
Pb nitrate induced liver hyperplasia exhibited sexual dimorphism.
Pre-administration with choline partially filled these sexual differences.
Significant down regulation of PKC p and PKC a activities occurred
during Pb induced proliferation.
Effect of Pb nitrate on protein kinase C (PKC) activity. A single dose of
Pb nitrate resulted in enhanced activity of PKC in the purified particulate
fraction of the rat liver, reached its peak activity by 24 h which lasted for
48 h. This was accompanied by increased frequency of mitotic cells.
These results indicate, Pb nitrate induced PKC activity may play a role in
liver cell proliferation.
Liver cell proliferation by enhanced DNA synthesis was observed with the
mitogens Cyproterone acetate, ethylene dibromide, and Pb nitrate as early
as 30 mints after treatment and persisted even after 5 days of treatment by
Pb nitrate administration.
hepatocytes isolated from pre neoplastic liver nodules have also exhibited
enhanced cell proliferation.
Stimulation of hepatocyte cell proliferation by Pb nitrate was not
accompanied by changes in liver levels of Hepatocyte growth factor
(HGF), Transforming growth factor-a (TGF-a), or TGF-pl m-RNA. Pb
nitrate treatment resulted in the enhancement of Tumor necrosis factor a at
a time preceding the onset of hepatocyte DNA synthesis, indicating its role
in Pb induced hepatic cell proliferation. The survival of Pb nitrate treated
rats decreased significantly with an after treatment of LPS
(lipopolysaccharide).
Reference
Tessitore et al.
(1994)
Tessitore et al.
(1994)
Liu et al. (1997)
Coni et al. (1992)
Shinozuka et al.
(1994)
-------
Table AX5-10.5 (cont'd). Lead-induced Liver Hyperplasia: Mediators and Molecular Mechanisms
Concentration
Duration
Species
Blood Lead
Effects"
Reference
>
X
15 mg/kgb. wt.
Pb acetate
Pb+ LPS group
analyzed after 14 h
and the rest after
24 h after Pb
administration
Male Sprague
Dawley rat
— Pb augments the lethality of endotoxin lipopolysaccharide (LPS) in rats
and enhances liver injury, which is further enhanced by TNF. Pb + LPS
treatment increased both serum TNF concentrations and TNF area as
compared to LPS alone, simultaneous administration of Pb with either
LPS or TNF, serum aspartate transaminase, alanine transaminase, alkaline
phosphatase, glutamyl trans peptidase and plasma triglyceride levels were
markedly increased.
Honchel et al.
(1991)
Pb nitrate 100 uM/kg
b. wt. i.v. single dose
100 umol/kgb. wt
Pb nitrate, single, i.v.
Multiple time points Male Wistar rats
of analyses
extending up to 48 h
after treatment
Multiple time points
of analyses up to
48 h
100 umol/kg b. wt. Multiple time points Male Sprague
single i.v. of analyses up to Dawley rats
80 h
100 umol/kgb. wt. Multiple time points Male Wistar rats
i.v. single dose of analyses up to
24 h
100 umol/kgb. wt. Multiple time point Male Sprague
i.v., single dose analyses up to 96 h Dawley rats
Pb nitrate and ethylene bromide induce liver cell proliferation via Ledda-Columbano
induction of TNFa. Dexa methasone, a known TNF inhibitor, decreases et al. (1994)
TNF expression and liver cell proliferation by these mitogens. These
studies support the fact that TNF might mediate hepatic cell proliferation
by Pb nitrate and ethylene bromide.
Pb nitrate (LN) treatment resulted in increased Brdu incorporation of Shinozuka et al.
hepatocytes and non parenchymal cells at 12 h after treatment and reached (1996)
the peak index at 36 h. Rats given a single i.v. of recombinant TNFa
enhanced proliferation in non parenchymal cells after 24 h, the labeling of
hepatocytes at 36 h. NAF, Nafenopin another mitogen which does not
induce liver TNFa, increased the number of labeled hepatocytes without
increasing the labeling of non parenchymal cells indicating that only Pb
nitrate induced proliferation is mediated by TNFa and these mitogens
initiate proliferation in different cells based on their capacity to stimulate
TNFa production.
Pb nitrate induces liver cell proliferation in rats without accompanying Kubo et al. (1996)
liver cell necrosis. This proliferation involves enhanced TNF mRNA and
levels but not hepatocyte growth factor. The role of TNF in Pb nitrate
induced liver cell proliferation is supported by the inhibition of TNF and
reduced hepatocyte proliferation by several TNF inhibitors.
Pb nitrate induced liver cell proliferation involves TNF a production, Menegazzi et al.
enhanced NF-KB activation increased hepatic levels of iNos mRNA as (1997)
opposed to other mitogens such as Cyproterone acetate or Nafenopine.
The role of neurotrophins, the nerve growth factor (NGF), the brain Nemoto et al.
derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) in Pb (2000 )
nitrate treated liver cells was studied. LN, treatment resulted in increased
in the levels of NGF, BDNF and NT-3. The increase in neurotrophin
receptors and the gene expression were correlate with liver weights. This
study demonstrates that Pb nitrate induced hyperplasia may be mediated
by neurotrophins.
-------
Table AX5-10.5 (cont'd). Lead-induced Liver Hyperplasia: Mediators and Molecular Mechanisms
Concentration
Duration
Species
Blood Lead
Effects"
Reference
>
X
Multiple doses
0-50 uM, culture
medium
50 uM Pb acetate,
culture medium
10 uM/110gb. wt,
single i.v.
lOumol/lOOgb. wt.
single i.v.
10 mmol/100 g,
Pb nitrate, i.v.
Multiple time points Hepatocytes from
up to 24 h Adult male Swiss-
mice, primary
24 h
Multiple time point
analyses up to
5 days
Rat hepatocyte
and Kupffer cell
and granulocyte
co-cultures
Adult male Wistar
rats
Multiple time points Male Wistar rats
up to 9 days
Multiple time points Male Wistar rats
Interaction between Pb and cytokines in hepatotoxicity- Pb potentiated Sieg and Billing
cytokine-induced oxidative stress by decreasing GSH and increased efflux (1997)
of Oxidized glutathione (GSSG). Combined treatment resulted in a
decline in intra cellular ATP concentration.
Pb stimulates intercellular signaling between Kupffer cells and Milosevic and
hepatocytes which increased synergistically at low lipopolysaccharide Maier (2000)
levels. These signals promote proteolytic hepatocyte killing in
combination with a direct cellular interaction between the granulocytes
and hepatocytes.
Pb nitrate induced hepatocyte apoptosis was prevented by pre-treatment Pagliara et al.
with gadolinium chloride, a Kupffer cell toxicant—Role for Kuffer cell in (2003a)
hepatocyte apoptosis.
Pb nitrate-induced liver hyperplasia in rats results in a significant increase Dini et al. (1993)
in the expression of aceyl glycoprotein receptor (ASGP-R) during the
involutive phase of Pb nitrate induced hyperplasia in rat-liver, which
coincided with the massive death by apoptosis of the same cells.
A significant rise in the galactose-specific receptors was also observed
3 days after the treatment. These studies demonstrate that carbohydrate
receptors regulate Pb nitrate induced liver cell apoptosis.
Demonstration of the expression of carbohydrate receptors on Kupffer Ruzittu et al. (1999)
cells. Pb nitrate induced apoptosis in Kupffer cells and internalization of
apoptotic cells (Phagocytes) is mediated by both Mannose and Galactose
receptors.
-------
Table AX5-10.5 (cont'd). Lead-induced Liver Hyperplasia: Mediators and Molecular Mechanisms
Concentration
Pb (No3)2, , i.v.
100uM/110g.b. wt
GdCl3
0.75 mg/100 g. b. wt,
i.v.
In vitro, 10 mM Pb
nitrate
Duration
1, 3, and 5 days
2, 4, or 24 h before Pb
nitrate injection.
Analyses at multiple
time points up to 24 h
Species
In vivo Adult
male Wistar rats
Hep G2 cells
Blood Lead Effects"
— Hepatic apoptosis induced by Pb nitrate in vivo is abolished by gadolium
chloride, a Kupffer cell toxicant that suppresses Kupffer cell activity and
reduces to half the apoptotic rate. Pb nitrate treatment also deprives the
hepatic cells from reduced glutathione and this process is reversed by
Gadolium chloride. Pb nitrate induces apoptosis in Kupffer cells, and
HepG2 cells in vitro.
—
Reference
Pagliara (2003b)
in Hep G2 cells and at
24 and 48 h in
Kupffer cells
Oi
Multiple 1, 2, 4 and 6 days
concentrations
varying from
300 nM-10 uM,
up to 100 uM in
certain in vitro expts
0-10 uM Pb acetate 24 and 48 h
in the culture medium
Hepatoma cell
line, H4-II-C3
H4-IIE— C3
hepatoma cell
culture model
— Acute effect of Pb on glucocorticoid regulation of Tyrosine
aminotransferase (TAT) in hepatoma cells. Pb treatment does not
significantly alter initial glucocorticoid receptor number or ligand binding.
Pb may perturb PKC mediated phosphorylations in the glucocorticoid-
TAT signal transduction system. Pb also may be increasing the turnover
of TAT by actions at transcription, translation and /or post translation.
— In HTC cells glucocarticoid signal transduction pathways involve calcium-
mediated events and PKC isoforms, Pb exposure interferes with calcium
mediated events and aberrant modulation of PKC activities and may
contribute to the over all toxicity of Pb.
Heiman and Toner
(1995)
Tonner and Heiman,
(1997)
aCYP—Cytochrome P-450
b. wt.—body weight
-------
Table AX5-10.6. Effect of Lead Exposure on Liver Heme Synthesis
>
X
Concentration Duration
75 mg Pb/kg b. wt, Multiple time point
i.p. analyses 0-30 h
10~5 ppm Pb nitrate Multiple analyses up
to24h
A. Triethyl Pb-3.5 Multiple analyses up
and 8.0 mg/kg to 28 days
b.wt.
Pb nitrate
3.5, 25, and
100 mg/kg
Single
Subcutaneous
B. In vitro, 30 min
10~3-10~9 M
triethyl Pb or Pb
nitrate
5 uM Pb acetate or Multiple analyses
Pb diethyldithio- from
carbomate Pb uptake 0-20 h
studies 0.33-10 uM
Per OS eqimolar 5 days
doses (17 uM Me/kg)
of SnCl2 or Pb
(CH3COO)2 every day
Species Blood Lead
C57 BL/6 mice —
RLC-GA1 Rat —
liver cell line
Adult male Control: 5.2 ug/dL
Fischer rats Triethyl Pb 8.0 mg/kg
b.wt.:
19.6 ug/dL
Pb nitrate
25 mg/kg b.wt.:
19.6 ug/dL
Pb nitrate
100 mg/kg b.wt.:
27.2 ug/dL
—
Rat primary —
hepatocyte
cultures
Female rabbits Control:
3.48 ug/100 cm3
Pb: 17.50 ug/100 cm3
Effects"
Pb poisoning decreases P-450 as a consequence of two different
mechanisms, a mechanism unrelated to heme where P-450 transcription is
inhibited (reduces the synthesis and activity), and a second mechanism
where by inhibition of heme synthesis occurs decreasing the heme
saturation of P450 and/or apo-P450 content.
Pb increases heme synthesis in RLC-GA1 in rat liver cell line, when
measured by the amount of 59 Fe incorporated into heme fraction.
Increased incorporation of59 Fe into the heme fraction of the Pb treated
cells was the result of increased uptake of iron 59 Fe into the heme fraction
of Pb treated cells.
Cellular degradation of Pb was not significantly affected by Pb.
Triethyl Pb chloride has a similar potency to inorganic Pb nitrate in
inhibiting ALAD both in vitro and in vivo. Liver and blood ALAD have
similar sensitivities to Pb compounds. Inhibition is reduced in the
presence of Zn.
Effect of Pb and diethyl dithiocarbomates on rat primary hepatocytes as
studied with Pb acetate and or Pb-diethyldithiocarbomate complex (Pb
DTC2i) labeled with 203Pb indicated that (Pb DTC2i) complex caused a
more rapid and stronger inhibition of ALAD activity than Pb acetate.
Uptake of Pb was rapid and higher with the complex than Pb acetate.
The complex also inhibited the ALAD activity in vitro when incubated
with purified ALAD enzyme.
Pb decreased liver and bone marrow ALAD, but had no change in the
Aminolevulinic acid synthetase (ALA-S) and increased erythrocyte free
protoporphyrin.
Reference
Jover et al. (1996)
Lake and
Gerschenson (1978)
Bondy(1986)
Oskarsson and
Hellstrom-Lindahl
etal. (1989)
Zareba and
Chmielnicka(1992)
-------
Table AX5-10.6 (cont'd). Effect of Lead Exposure on Liver Heme Synthesis
>
X
oo
Concentration
Pb 500 ppm in
drinking water
0.5or2.4uMPb
acetate in culture
medium
500 ppm Pb in
drinking water
A. Cu deficient diet:
1 mg/kg Cu in
the diet
B. Moderately
deficient:
2 mg/kg
C. High Zn diet:
60 mg/kg b. wt.
1200 mg/kg b. wt. Pb
acetate in diet, Sub
acute toxic studies
400 mg/Pb
Duration
14 days
Analyses at multiple
time points,
0-28 days
Rat exposure 62 days
Human occupational
exposure
0.3-38 yrs.
4 wks
4 wks
Species
Male ddY mice
Hepatocyte
cultures on 3T3
cells
A. Male Wistar
rats
B. Pb smelt
workers, males
Weanling
Sprague Dawley
rats
Broiler chickens
Blood Lead Effects"
— Urinary excretion of (3-Aminoisobutyric acid (ABA) and 8-aminolevulinic
acid (ALA) increased significantly in mice exposed to Pb in drinking
water for 14 days. The degree of increasing excretion for ALA was higher
than urinary ABA. Liver and kidney ALA dehydratase was inhibited,
while ALA synthatase was not affected.
— Hepatocyte cultures on 3T3 cells produce and excrete porphyrins for
28 days. Pb exposure for 4 wks alters cell morphology and produces
cytotoxic effects that could be monitored by altered porphyrin excretion.
— Pb exposure significantly increases the urinary ALA (Aminolevulinic
acid) and Coproporphyrins (CP-III>CP-I in rats and exposed workers.
Urinary 5-hydroxy indole acetic acid was not influenced by Pb exposure.
— High Zn in the diet reduces plasma copper, but not plasma ceruloplasmin
activity or the recovery of plasma copper or ceruloplasmin activity after
oral copper sulphate of Cu-deficient rats. High dietary Zn also modifies
the response of plasma SOD activity to dietary copper , but does not
influence RBC SOD activity.
— Liver porphyrin levels increased during Pb toxicosis. Concurrent
administration of selenium or monensin in the feed further enhances this
process.
Reference
Tomokuni et al.
(1991)
Quintanilla-Vega
etal. (1995)
Ichiba and
Tomokuni (1987)
Panemangalore and
Bebe (1996)
Khan and Szarek
(1994)
0-100 uM Pb acetate
in the culture medium
19 h
Primary Rat and
chick embryo
hepatocyte
cultures
Formation of Zn protoporphyrins in cultured hepatocytes. Pb did not
specifically increase Zinc protoporphyrin accumulation or alter iron
availability in cultured hepatocytes.
Jacobs et al. (1998)
-------
Table AX5-10.6 (cont'd). Effect of Lead Exposure on Liver Heme Synthesis
>
X
Concentration Duration
Pb acetate, 160 mg/L, 8 wks
semi liquid diet, oral
Pb acetate, 10 minpre incubation
0.0625 uM-32 uM, and 20 minute
in vitro incubation
1, 5, or 10 mg/kg 3 days
b. wt. Pb acetate or
nitrate, i.p.
10"4 M Pb acetate for
Hep G2 cells
10 mg Pb/kg b. wt. as Analyses at multiple
Pb acetate , i.p., single time points up to 72 h
injection
10 and 100 uM Pb
acetate
Species
Male Wistar rats
Rabbit
reticulocytes
A. Transgenic
mice carrying
chimeric
human TF
gene
B. Hep G2 cells
Transgenic mice
and Hep G 2
cells
Blood Lead Effects"
— Rats exposed to Pb had a higher blood and liver Pb, increased erythrocytic
protoporphyrin. Pb exposure also resulted in hypoactivity of
aminolevulinate dehydrase.
Rats exposed to ethanol and Pb had altered abnormalities in heme similar
to animals exposed to Pb alone.
Hepatic levels of Zn decreased significantly only in animals exposed to
both.
Hepatic GSH, urinary ALA and porphyrin levels were maintained
similarly in all the groups.
Transferrin bound iron uptake by Pb was also inhibited by Pb at higher
concentrations such as 4 uM.
— The effect of Pb on ferrous iron transport is similar between Pb chloride,
acetate, and nitrate and reversible.
Uptake of ferrous iron into all (heme, cytosolic and stromal fractions) was
inhibited by low concentrations of Pb.
50% inhibition in the uptake by cytosol occurred at 1 uM Pb.
— These studies present evidence for the modulation of the synthesis of
human transferrin by Pb. In transgenic mouse with chimeric human
chloromphenical acetyl transferase Pb regulates human Transferrin (TF)
transgenes at the m RNA level. Liver catalase (CAT) enzyme activity,
CAT protein, and TF-CAT m-RNA levels were all suppressed. Pb did not
alter other liver proteins, mouse TF and Albumin.
— Pb suppressed synthesis of Transferrin protein in cultured human
hepatoma Hep G2 cells.
— Pb suppresses human transferrin synthesis by a mechanism different from
acute phase response. Common proteins such as C3 and albumin
associated with acute phase response were not altered by Pb. Pb acetate
suppresses 35S-transferrin protein synthesis and m-RNA levels in Hep G2
cells and transgenic mice, while LPS altered only protein levels.
Reference
Santos et al. (1999)
Qian and Morgan
(1990)
Adrian etal. (1993)
Barnum-Huckins
etal. (1997)
aCYP—Cytochrome P-450
b. wt = body weight
-------
>
X
Table AX5-10.7. Lead and In Vitro Cytotoxicity in Intestinal Cells
Compound and
Concentration
HgCl2, CdCl2, Ti2
S04, Pb(N03)2-
concentration not
given clearly,
Butathionine, up to
ImM
Glutathione 1 mM
N-Acetyl cysteine,
ImM
Duration Species
Cell proliferation 1-407, Intestinal
assays 48 h epithelial cell
line.
Glutathione depletion
assays 48 h
Sulphahydryl
repletion studies.
Blood Lead Effects"
— Rank order cytotoxicity of various metal salts in 1-407 intestinal epithelial
cells in terms of LC50 values— HgCl2 (32 uM) > CdCl2 (53 uM), CuCl2
(156nM)>Ti2SO4
(377 uM) > Pb (NO3)2(1.99 mM)
Role of Glutathione, in the cytotoxicity of these metals by the assessment
of GSH depletion by Butathionine sulfoxamine pretreatment at non
cytotoxic concentration increased the toxicity of HgCl2 (5. 7-fold), and
CuCl2(1.44-fold).
Administration of glutathione, with either HgCl2 or CdCl2 did not protect
the cells against the toxicity.
Af-acetyl cysteine reduced the cytotoxicity of mercury.
Reference
Keogh et al. (1994)
aCYP—Cytochrome P-450
OO
O
-------
Table AX5-10.8. Lead and Intestinal Uptake—Effect on Ultrastructure, Motility, Transport, and Miscellaneous
Compound and
Concentration
Pb acetate, 0.1%, in
drinking water
Duration Species
Multiple analyses at Male Wistar rats
2, 30, and 60 days
after Pb exposure
Blood Lead Effects"
— Small intestinal goblet cells are involved in Pb detoxification.
Pb treatment for 30 days produces characteristic goblet cells in the
intestine and Pb appears in conjunction with goblet cell membrane.
Authors
Tomczok et al.
(1988)
Prolonged exposure to Pb more than 30 days caused silver sulphide
deposition (indicative of heavy metal deposition) in the mucus droplets
of cytoplasmic goblet cells.
>
X
oo
100 mg/Pb acetate/kg
b. wt.
Added Pb concentration
in the milk—0-80 ug/mL
Multiple analyses at
2, 30 and 60 days
Male Wistar rats
Adult and Infant
rats (16 days)
Fresh or frozen rat
or Avian milk
Pb poisoning changes the ultra structure of intestine.
30 days Pb exposed rat intestinal enterocytes showed numerous, small
rough-membraned vesicles and prominent, dilated golgi complexes, in
their cytoplasm.
By 60th day, Pb-exposed rats had a vacuolated cytoplasm and prominent
golgi filled with vacuoles.
90% of Pb in rat and bovine milk was found associated with caseine
micelles regardless of whether the milk is labeled in vitro or in vivo with
203 Pb. Similarly Pb in infant milk formula was also predominantly
associated with casein, however, to a much lower extent than rat and
bovine milk formulae.
Tomczok et al.
(1991)
Beach and Henning
(1988)
Pb tracer studies indicated that in infant rats, as the milk traversed through
the intestine, in the collected luminal fluid, Pb was primarily associated
with casein curd and remained as a nonprecipitable, nondialyzable fraction
as it moved to the small intestine, indicating that Pb remains with protein
fraction as it traverses through the stomach and small intestine fraction.
Pb as Pb acetate, for 0.5-
10.0 uM, Zn as Zn
acetate 0, 5, 10, or 50 uM
Temperature variation
Expts, 5 uM Pb, and
incubated for 10 min at 4,
22, or 37 °C
5, 10, 30 or 60 min,
Simultaneously with
Pb for 10 min
Incubation time
10 min
IEC-6 normal rat
intestinal
epithelial cells
Pb uptake by IEC-6 cells depends on the extracellular Pb concentration. Dekaney et al.
Pb transport in IEC-6 cells is time and temperature dependent, involves (1997)
sulphahydryl groups, and is decreased by the presence of Zn.
-------
Table AX5-10.8 (cont'd). Lead and Intestinal Uptake—Effect on Ultrastructure, Motility, Transport, and Miscellaneous
Compound and
Concentration
Duration
Species
Blood Lead
Effects"
Authors
>
X
oo
to
OECD
(Organisation for
Economic Co-operation
and Development)
medium was artificially
contaminated at 1, 3, 5, or
10 times the Dutch
intervention value of
530 mg/Pb/kg dry wt. Pb
containing medium was
presented at the apical
surface of the cells in 2
mL DMEM/chyme.
Neutral red uptake
studies had
DMEM/chime with low
5 uM and high 50 uM Pb
content
44 mg/kg/d Pb as
53 mmol/L Pb acetate
2.5 mg/mL Pb acetate in
drinking water
Cell viability
studies—24 h
incubation.
Pb transport studies,
1,3, 5, and 24 h
4 wks
55 days
Rat
Colonic segments
taken from
chronically
exposed guinea
pigs
Exposed:
80 ug/dL
Transport of bioaccessible Pb across the intestinal epithelium—In Coco-2
cells exposed to artificial chime, with in 24 hrs. App. 27% of the Pb was
associated with the cells and 3% were transported across the cell
monolayer. Pb associated with cells showed a linear relationship with the
Pb available in the system.
Results indicate that only a fraction of the bioavailable Pb is transported
across the intestinal epithelium.
On the basis of Pb speciation in chime, It could be attributed that
dissociation of labile Pb species, such as Pb phosphate, and Pb bile
complexes and subsequent transport of the released free metal ions flow
toward the intestinal membrane.
Oomen et al. (2003)
Pb exposure significantly decreases the amplitude of contraction in rat
duodenum.
Colonic propulsive activity as measured by the velocity of the
displacement of the balloon, from the oral to the aboral end, did not get
affected significantly by Pb treatment. In longitudinal muscle-myenteric
plexus preparations of distal ileum, addition of Pb nitrate (100 urn) caused
slight increase in cholinergic contractions.
Karmakar and
Anand (1989)
Rizzietal. (1989)
100 uM Pb nitrate,
in vitro
Duration not
specified
Muscle-myenteric
plexus
preparations of
distal ileum of
controlled animals
Moderate decrease of electrically induced cholinergic contractions.
-------
Table AX5-10.8 (cont'd). Lead and Intestinal Uptake—Effect on Ultrastructure, Motility, Transport, and Miscellaneous
Compound and
Concentration
Duration
Species
Blood Lead
Effects"
Authors
40 uM-240 uM Tri ethyl 7.5 sec-2 min
Pb added in a cumulative
manner in vitro to mid-
ileal portion.
Swiss mice JVI1
ileum
1. Peristaltic contractile activity of ileum as measured as a change in
period duration and force amplitude indicated that tri ethyl Pb (TEL)
concentrations of <40 uM had no obvious effects on these parameters.
2. In the concentration range between 40 uM-120 uM, tri ethyl Pb
affected the rhythm of contraction in a concentration dependent manner
with elongation in period and reduction in force amplitude.
3. At concentrations above 120 uM, TEL induced irreversible dramatic
changes in the ileal contractile activity.
Shraideh (1999)
>
X
aCYP—Cytochrome P-450
oo
-------
Table AX5-10.9. Lead, Calcium, and Vitamin D Interactions, and Intestinal Enzymes
>
X
oo
Compound and
Concentration Duration
Ca— 0.5% in diet 10 days
(low calcium)
1.2% in diet
(high calcium)
Pb — 0.8% in the diet
as Pb chloride
Species
White Leghorn
Cockerels
Blood Lead Effects11
— Dietary Pb affects intestinal Ca absorption in two different ways
depending on the dietary Ca status.
A. In chicks fed low Ca diet (0.05%), ingested Pb inhibited intestinal
47Ca absorption, intestinal Calbindin D, and alkaline phosphatase
synthesis in a dose dependent fashion.
B. In normal calcium diets (1.2%) Pb exposure had no bearing on the
Authors
Fullmer and Rosen
(1990)
Ca—0.1% or 1.2% in the
diet with Pb—0.1-0.8%
as Pb chloride in the diet
1 or 2 wks
Leghorn
Cockerels
intestinal Ca absorption, or Calbindin D, or Alkaline phosphatase
synthesis and in fact elevated their levels at higher Pb concentrations.
These results indicate that the primary effects of Pb in both cases,
occur at or prior to intestinal protein synthesis involving
Cholecalciferol endocrine system.
—Dietary Ca deficiency, initially
(1st week) stimulates Ca absorption and Calbindin D levels regardless of
dietary Pb intake.
—At 2 wks, this response is reversed by Pb.
—Intestinal Pb absorption was enhanced by Ca deficiency initially and
was inhibited by prolonged dietary Pb intake.
—Intestinal Pb absorption was increased in adequate Ca situation, but
only after 2 wks at the lower levels of dietary Pb.
Fullmer (1991)
Ca—0.1-1.2%
Pb—0.8%
2 wks
White Leghorn
Cockerels
Interactions between dietary Pb and Ca-influence on serum vitamin D
levels.
—Pb ingestion and Ca deficiency alone or in combination generally
increased serum 1,25 (OH)2 D levels over the most of the range of
dietary Pb and Ca.
—In severe Ca deficiency, Pb ingestion resulted in significant decreases in
hormone concentration.
—Similarities in response profiles for 1,25 ( OH)2 D, intestinal Ca
absorption and Calbindin- D suggested major interactions between Pb
and calcium mediated changes via circulatingl,25(OH)2 D
concentration.
Fullmer (1997)
-------
Table AX5-10.9 (cont'd). Lead, Calcium, and Vitamin D Interactions, and Intestinal Enzymes
>
X
oo
Compound and
Concentration
Pb, Alkaline phosphatase
and Ca2+ ATPase
on inn mA/r
z.u— lu.u mivi
Pb, Sucrase
0.5 mM-6.0 mM
Pb, y-glutamyl
transpeptidasel.0-10 mM
Pb, Acetyl choline
esterase 10.00-35.00 mM
Oral Pb in Similac or
apple juice adjusted for
attainment of blood Pb
levels 35^10 ug/dL.
Succimer 30 mg/kg/d
204 Pb 24. 5 nM followed
by 206 Pb 352 nM,
Single dose
Duration Species Blood Lead
Incubation time not Male Albino rats
specified
Administered from Female infant Pb-exposed:
8th day post partum, Rhesus Monkeys 35-40 ug/dL
until age 26 wks
Two successive
19 days at age 53 wks
and 65 wks
Administered
immediately before
chelation
Effects"
Pb inhibited the activity of several intestinal brush border enzymes such as
Ca2+- ATPase, Sucrase, y-glutamyl-transpeptidase and acetyl choline
esterase with the exception of alkaline phosphatase. Inhibition of Ca2+-
ATPase was competitive and that of the other enzymes is by non-
competitive means.
Effect of oral succimer chelation on the Gastro intestinal absorption and
the whole body retention of Pb
Radio isotope Pb tracer technique
Succimer significantly reduced Gastro intestinal absorption of Pb and
increased urinary excretion of Pb
The initial decrease in whole body Pb by 10% was over come when
majority of administered tracer was retained in the body after 5 days of
treatment.
Authors
Gupta etal. (1994)
Creminetal. (2001)
aCYP—Cytochrome P-450
-------
ANNEX TABLES AX5-11
AX5-186
-------
Table AX5-11.1. Lead-binding Proteins
>
X
oo
Source
Goyer(1968)
Goyeretal. (1970a,b)
Choie and Richter (1972)
Moore etal. (1973)
Moore and Goyer (1974)
Shelton and Egle (1982)
Egle and Shelton (1986)
Oskarsson et al. (1982)
Mistry etal. (1985)
Fowler and DuVal (1991)
Organ Species
Kidney Rat
Kidney Rat
Kidney Rat
Kidney Rat
Kidney Rat
Kidney Rat
Brain Rat, mouse,
dog, guinea
pig, and
chicken
Kidney Rat
cytosol and
brain
Kidney Rat
cytosol
Kidney Rat
cytosol
Molecular
Weight Protein Properties
Intranuclear Pb inclusion
bodies
Pb is concentrated in the
intranuclear inclusion body
Initial inclusion bodies in
cytoplasm
Protein in inclusion bodies is
acidic, with high levels of
aspartic a, glutamic a, glycine
and cystine
Inclusion body
protein is
27.5 kDa
Inclusion body is Named p32/6 . 3
32 kDa with pi
of6.3
p32/6.3 found
11. 5 and 63 kDa
11.5 kDa, 63 kDa, Respective Kd values: 1 3 ,
> 200 kDa 40, 123 nM
Cleavage product of alpha-2
microglobulin
Inducible Separation Technique
Yes
Yes
Yes
Yes
Yes Acrylamide gel electrophoresis
Yes Two-dimensional gel electrophoresis
No
No 203Pb binding followed by Sephadex
G-75 or G-200 chromatography, then
SDS-PAGE
No 203Pb binding followed by Sepharose-
6B column chromatography
No Chromatography followed by reverse
phase HPLC, then production of
antibodies Kdl 0-8 M
-------
Table AX5-11.1 (cont'd). Lead-binding Proteins
>
X
oo
oo
Source
Smith etal. (1998)
Goeringetal. (1986)
DuVal and Fowler (1989)
Fowler etal. (1993)
Quintanilla-Vega et al.
(1995)
Raghavan and Gonick
(1977)
Raghavan et al. (1980)
Raghavan et al. (1981)
Gonick etal. (1985)
Ong and Lee (1980)
Lolin and O'Gorman
(1988)
Organ
Kidney cortex
Brain
Brain
Kidney and
brain
Brain
RBC
RBC
RBC
RBC
RBC
RBC
Species
Human
Rat
Rat
Monkey
Human
Human Pb-
workers
Human Pb-
workers
Human Pb
workers
Human Pb
workers
Normal human
Human Pb
workers
Molecular
Weight
9 kDa and 5 kDa
12kDa
23 kDa
Brain Pb-binding
protein larger than
kidney
5 kDa and 20 kDa
10 kDa
10 kDa
10 kDa
12 kDa, pi 5. 3,
and 30 kDa
67 kDa
Low molecular
weight
Protein Properties
ACBP and thymosin B4
Glutamic a, aspartic a,
cysteine. NotMT
aspartic a, glutamic a,
glycine, serine
Thymosin B4 and
unidentified protein
Pb-binding protein absent in
controls, low in symptomatic,
high in asymptomatic
Pb in membrane fraction
correlates inversely with Na-
K-ATPase
Glycine, histidine, aspartic a,
leucine
Thought to be hemoglobin
Pb-binding protein correlates
with restored ALAD
Inducible
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Separation Technique
Sephadex G-75 fractions <30 kDa,
Sephadex A-25, then HPLC
Labeled (203Pb) cytosol applied to
Sephadex G-75
Labeled cytosol applied to Sephadex G-
75, DEAE, followed by SDS-PAGE
Sephadex G-75 and DEAE
Sephadex G-75, A-25 DEAE, reversed
phase HPLC
210Pb binding, Sephadex G-75,
followed by SDS-PAGE
210Pb binding, Sephadex G-75
210Pb binding, Sephadex G-75
Sephadex G-75, HPLC, isoelectric
focusing, SDS-PAGE
203Pb binding, Sephadex G-75
Sephadex G-75, Pb measured by atomic
absorption
-------
Table AX5-11.1 (cont'd). Lead-binding Proteins
X
-------
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United States October 2006
EPW600
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EPA/600/R-05/144bF
October 2006
Air Quality Criteria for Lead
Volume II
National Center for Environmental Assessment-RTF Division
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, NC
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PREFACE
National Ambient Air Quality Standards (NAAQS) are promulgated by the United States
Environmental Protection Agency (EPA) to meet requirements set forth in Sections 108 and 109
of the U.S. Clean Air Act. Those two Clean Air Act sections require the EPA Administrator
(1) to list widespread air pollutants that reasonably may be expected to endanger public health or
welfare; (2) to issue air quality criteria for them that assess the latest available scientific
information on nature and effects of ambient exposure to them; (3) to set "primary" NAAQS to
protect human health with adequate margin of safety and to set "secondary" NAAQS to protect
against welfare effects (e.g., effects on vegetation, ecosystems, visibility, climate, manmade
materials, etc); and (5) to periodically review and revise, as appropriate, the criteria and NAAQS
for a given listed pollutant or class of pollutants.
Lead was first listed in the mid-1970's as a "criteria air pollutant" requiring NAAQS
regulation. The scientific information pertinent to Pb NAAQS development available at the time
was assessed in the EPA document Air Quality Criteria for Lead; published in 1977. Based on
the scientific assessments contained in that 1977 lead air quality criteria document (1977 Lead
AQCD), EPA established a 1.5 |ig/m3 (maximum quarterly calendar average) Pb NAAQS in
1978.
To meet Clean Air Act requirements noted above for periodic review of criteria and
NAAQS, new scientific information published since the 1977 Lead AQCD was later assessed in
a revised Lead AQCD and Addendum published in 1986 and in a Supplement to the 1986
AQCD/Addendum published by EPA in 1990. A 1990 Lead Staff Paper, prepared by EPA's
Office of Air Quality Planning and Standards (OPQPS), drew upon key findings and conclusions
from the 1986 Lead AQCD/Addendum and 1990 Supplement (as well as other OAQPS-
sponsored lead exposure/risk analyses) in posing options for the EPA Administrator to consider
with regard to possible revision of the Pb NAAQS. However, EPA chose not to revise the Pb
NAAQS at that time. Rather, as part of implementing a broad 1991 U.S. EPA Strategy for
Reducing Lead Exposure, the Agency focused primarily on regulatory and remedial clean-up
efforts to reduce Pb exposure from a variety of non-air sources that posed more extensive public
health risks, as well as other actions to reduce air emissions.
-------
The purpose of this revised Lead AQCD is to critically assess the latest scientific
information that has become available since the literature assessed in the 1986 Lead
AQCD/Addendum and 1990 Supplement, with the main focus being on pertinent new
information useful in evaluating health and environmental effects of ambient air lead exposures.
This includes discussion in this document of information regarding: the nature, sources,
distribution, measurement, and concentrations of lead in the environment; multimedia lead
exposure (via air, food, water, etc.) and biokinetic modeling of contributions of such exposures
to concentrations of lead in brain, kidney, and other tissues (e.g., blood and bone concentrations,
as key indices of lead exposure).; characterization of lead health effects and associated exposure-
response relationships; and delineation of environmental (ecological) effects of lead. This final
version of the revised Lead AQCD mainly assesses pertinent literature published or accepted for
publication through December 2005.
The First External Review Draft (dated December 2005) of the revised Lead AQCD
underwent public comment and was reviewed by the Clean Air Scientific Advisory Committee
(CASAC) at a public meeting held in Durham, NC on February 28-March 1, 2006. The public
comments and CASAC recommendations received were taken into account in making
appropriate revisions and incorporating them into a Second External Review Draft (dated May,
2006) which was released for further public comment and CASAC review at a public meeting
held June 28-29, 2006. In addition, still further revised drafts of the Integrative Synthesis
chapter and the Executive Summary were then issued and discussed during an August 15, 2006
CASAC teleconference call. Public comments and CASAC advice received on these latter
materials, as well as Second External Review Draft materials, were taken into account in making
and incorporating further revisions into this final version of this Lead AQCD, which is being
issued to meet an October 1, 2006 court-ordered deadline. Evaluations contained in the present
document provide inputs to an associated Lead Staff Paper prepared by EPA's Office of Air
Quality Planning and Standards (OAQPS), which poses options for consideration by the EPA
Administrator with regard to proposal and, ultimately, promulgation of decisions on potential
retention or revision, as appropriate, of the current Pb NAAQS.
Preparation of this document has been coordinated by staff of EPA's National Center for
Environmental Assessment in Research Triangle Park (NCEA-RTP). NCEA-RTP scientific
staff, together with experts from academia, contributed to writing of document chapters. Earlier
Il-iv
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drafts of document materials were reviewed by scientists from other EPA units and by non-EPA
experts in several public peer consultation workshops held by EPA in July/August 2005.
NCEA acknowledges the valuable contributions provided by authors, contributors, and
reviewers and the diligence of its staff and contractors in the preparation of this document. The
constructive comments provided by public commenters and CASAC that served as valuable
inputs contributing to improved scientific and editorial quality of the document are also
acknowledged by NCEA.
DISCLAIMER
Mention of trade names or commercial products in this document does not constitute
endorsement or recommendation for use.
II-v
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Air Quality Criteria for Lead
(Second External Review Draft)
VOLUME I
EXECUTIVE SUMMARY E-l
1. INTRODUCTION 1-1
2. CHEMISTRY, SOURCES, AND TRANSPORT OF LEAD 2-1
3. ROUTES OF HUMAN EXPOSURE TO LEAD AND OBSERVED
ENVIRONMENTAL CONCENTRATIONS 3-1
4. TOXICOKINETICS, BIOLOGICAL MARKERS, AND MODELS OF LEAD
BURDEN IN HUMANS 4-1
5. TOXICOLOGICAL EFFECTS OF LEAD IN LABORATORY ANIMALS
AND IN VITRO TEST SYSTEMS 5-1
6. EPIDEMIOLOGIC STUDIES OF HUMAN HEALTH EFFECTS
ASSOCIATED WITH LEAD EXPOSURE 6-1
7. ENVIRONMENTAL EFFECTS OF LEAD 7-1
8. INTEGRATIVE SYNTHESIS OF LEAD EXPOSURE/HEALTH
EFFECTS INFORMATION 8-1
VOLUME II
CHAPTER 4 ANNEX (TOXICOKINETICS, BIOLOGICAL MARKERS, AND
MODELS OF LEAD BURDEN IN HUMANS) AX4-1
CHAPTER 5 ANNEX (TOXICOLOGICAL EFFECTS OF LEAD IN
LABORATORY ANIMALS AND IN VITRO TEST SYSTEMS) AX5-1
CHAPTER 6 ANNEX (EPIDEMIOLOGIC STUDIES OF HUMAN HEALTH
EFFECTS ASSOCIATED WITH LEAD EXPOSURE) AX6-1
CHAPTER 7 ANNEX (ENVIRONMENTAL EFFECTS OF LEAD) AX7-1
Il-vi
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Table of Contents
Page
PREFACE iii
DISCLAIMER v
List of Tables viii
Authors, Contributors, and Reviewers xi
U.S. Environmental Protection Agency Project Team for Development
of Air Quality Criteria for Lead xvii
U.S. Environmental Protection Agency Science Advisory Board (SAB)
Staff Office Clean Air Scientific Advisory Committee (CASAC) xix
Abbreviations and Acronyms xxi
AX6. CHAPTER 6 ANNEX (EPIDEMIOLOGIC STUDIES OF HUMAN
HEALTH EFFECTS ASSOCIATED WITH LEAD EXPOSURE AX6-1
ANNEX TABLES AX6-2 AX6-2
ANNEX TABLES AX6-3 AX6-29
ANNEX TABLES AX6-4 AX6-69
ANNEX TABLES AX6-5 AX6-129
ANNEX TABLES AX6-6 AX6-168
ANNEX TABLES AX6-7 AX6-182
ANNEX TABLES AX6-8 AX6-206
ANNEX TABLES AX6-9 AX6-220
REFERENCES AX6-260
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List of Tables
Number Page
AX6-2.1 Prospective Longitudinal Cohort Studies of Neurocognitive Ability in
Children AX6-3
AX6-2.2 Meta- and Pooled-Analyses of Neurocognitive Ability in Children AX6-9
AX6-2.3 Cross-Sectional Studies of Neurocognitive Ability in Children AX6-11
AX6-2.4 Effects of Lead on Academic Achievement in Children AX6-14
AX6-2.5 Effects of Lead on Specific Cognitive Abilities in Children —
Attention/Executive Functions, Learning, and Visual-spatial Skills AX6-17
AX6-2.6 Effects of Lead on Disturbances in Behavior, Mood, and Social
Conduct in Children AX6-19
AX6-2.7 Effects of Lead on Sensory Acuities in Children AX6-23
AX6-2.8 Effects of Lead on Neuromotor Function in Children AX6-24
AX6-2.9 Effects of Lead on Direct Measures of Brain Anatomical
Development and Activity in Children AX6-25
AX6-2.10 Reversibility of Lead-related Deficits in Children AX6-27
AX6-3.1 Neurobehavioral Effects Associated with Environmental
Lead Exposure in Adults AX6-30
AX6-3.2 Symptoms Associated with Occupational Lead Exposure in Adults AX6-33
AX6-3.3 Neurobehavioral Effects Associated with Occupational Lead
Exposure in Adults AX6-36
AX6-3.4 Meta-analyses of Neurobehavioral Effects with Occupational
Lead Exposure in Adults AX6-49
AX6-3.5 Neurophysiological Function and Occupational Lead
Exposure in Adults AX6-51
AX6-3.6 Evoked Potentials and Occupational Lead Exposure in Adults AX6-56
AX6-3.7 Postural Stability, Autonomic Testing, Electroencephalogram,
Hearing Thresholds, and Occupational Lead Exposure in Adults AX6-59
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List of Tables
(cont'd)
Number Page
AX6-3.8 Occupational Exposure to Organolead and Inorganic Lead in Adults AX6-63
AX6-3.9 Other Neurological Outcomes Associated with Lead Exposure in Adults.... AX6-66
AX6-4.1 Renal Effects of Lead in the General Population AX6-70
AX6-4.2 Renal Effects of Lead in the Occupational Population AX6-81
AX6-4.3 Renal Effects of Lead in the Patient Population AX6-104
AX6-4.4 Renal Effects of Lead on Mortality AX6-120
AX6-4.5 Renal Effects of Lead in Children AX6-122
AX6-5.1 Effects of Lead on Blood Pressure and Hypertension AX6-130
AX6-5.2 Effects of Lead on Cardiovascular Morbidity AX6-159
AX6-5.3 Effects of Lead on Cardiovascular Mortality AX6-162
AX6-5.4 Cardiovascular Effects of Lead on Children AX6-166
AX6-6.1 Placental Transfer of Lead from Mother to Fetus AX6-169
AX6-6.2 Lead Exposure and Male Reproduction: Semen Quality AX6-174
AX6-6.3 Lead Exposure and Male Reproduction: Time to Pregnancy AX6-178
AX6-6.4 Lead Exposure and Male Reproduction: Reproductive History AX6-180
AX6-7.1 Recent Studies of Lead Exposure and Genotoxicity AX6-183
AX6-7.2 Key Occupational Studies of Lead Exposure and Cancer AX6-186
AX6-7.3 Key Studies of Lead Exposure and Cancer in the General Population AX6-192
AX6-7.4 Other Studies of Lead Exposure and Cancer AX6-194
AX6-8.1 Effects of Lead on Immune Function in Children AX6-207
AX6-8.2 Effects of Lead on Immune Function in Adults AX6-211
Il-ix
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List of Tables
(cont'd)
Number Page
AX6-9.1 Effects of Lead on Biochemical Effects in Children AX6-221
AX6-9.2 Effects of Lead on Biochemical Effects in Adults AX6-223
AX6-9.3 Effects of Lead on Hematopoietic System in Children AX6-231
AX6-9.4 Effects of Lead on Hematopoietic System in Adults AX6-234
AX6-9.5 Effects of Lead on the Endocrine System in Children AX6-241
AX6-9.6 Effects of Lead on the Endocrine System in Adults AX6-243
AX6-9.7 Effects of Lead on the Hepatic System in Children and Adults AX6-251
AX6-9.8 Effects of Lead on the Gastrointestinal System AX6-253
AX6-9.9 Effects of Lead on Bone and Teeth in Children and Adults AX6-255
AX6-9.10 Effects of Lead on Ocular Health in Children and Adults AX6-258
II-x
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Authors, Contributors, and Reviewers
CHAPTER 4 ANNEX (TOXICOKINETICS, BIOLOGICAL MARKERS, AND
MODELS OF LEAD BURDEN IN HUMANS)
Chapter Managers/Editors
Dr. James Brown—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Principal Authors
Dr. Brian Gulson—Graduate School of the Environment, Macquarie University
Sydney, NSW 2109, Australia
Contributors and Reviewers
Dr. Lester D. Grant—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. John Vandenberg—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
CHAPTER 5 ANNEX (TOXICOLOGICAL EFFECTS OF LEAD IN HUMANS
AND LABORATORY ANIMALS)
Chapter Managers/Editors
Dr. Anuradha Mudipalli—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Srikanth Nadadur—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Lori White—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Il-xi
-------
Authors, Contributors, and Reviewers
(cont'd)
Principal Authors
Dr. Anuradha Mudipalli—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Stephen Lasley—Dept. of Biomedical and Therapeutic Sciences, Univ. of Illinois College of
Medicine, PO Box 1649, Peoria, IL 61656
Dr. Lori White—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Gary Diamond— Syracuse Research Corporation, 8191 Cedar Street, Akron, NY 14001
Dr. N.D. Vaziri—Division of Nephrology and Hypertension, University of California - Irvine
Medical Center, 101, The City Drive, Bldg 53, Room #125. Orange, CA 92868
Dr. John Pierce Wise, Sr.—Maine Center for Toxicology and Environmental Health,
Department of Applied Medical Sciences, 96 Falmouth Street, PO Box 9300, Portland, ME
04104-9300
Dr. Harvey C. Gonick—David Geffen School of Medicine, University of California at
Los Angeles, 201 Tavistock Ave, Los Angeles, CA 90049
Dr. Gene E. Watson—University of Rochester Medical Center, Box 705, Rochester, NY 14642
Dr. Rodney Dietert—Institute for Comparative and Environmental Toxicology, College of
Veterinary Medicine, Cornell University, Ithaca, NY 14853
Contributors and Reviewers
Dr. Lester D. Grant—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Paul Reinhart—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Michael Davis—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. David A. Lawrence—Dept of Environmental and Clinical Immunology, Empire State Plaza
P.O. Box 509, Albany, NY 12201
-------
Authors, Contributors, and Reviewers
(cont'd)
Contributors and Reviewers
(cont'd)
Dr. Michael J. McCabe, Jr.—Dept of Environmental Medicine, University of Rochester,
575 Elmwood Avenue, Rochester, NY 14642
Dr. Theodore I. Lidsky—New York State Institute for Basic Research, 1050 Forest RD,
Staten Island, NY 10314
Dr. Mark H. Follansbee—Syracuse Research Corporation, 8191 Cedar St. Akron, NY 14001
Dr. William K. Boyes—National Health and Environmental Effects Research Laboratory,
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Philip J. Bushnell—National Health and Environmental Effects Research Laboratory,
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Ms. Beth Hassett-Sipple—Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Dr. Zachary Pekar—Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Dr. John Vandenberg—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
CHAPTER 6 ANNEX (EPIDEMIOLOGICAL STUDIES OF AMBIENT LEAD
EXPOSURE EFFECTS)
Chapter Managers/Editors
Dr. Jee Young Kim—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Dennis Kotchmar—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. David Svendsgaard—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
-------
Authors, Contributors, and Reviewers
(cont'd)
Principal Authors
Dr. David Bellinger—Children's Hospital, Farley Basement, Box 127, 300 Longwood Avenue,
Boston, MA 02115
Dr. Margit Bleecker—Center for Occupational and Environmental Neurology, 2 Hamill Road,
Suite 225, Baltimore, MD 21210
Dr. Gary Diamond— Syracuse Research Corporation, 8191 Cedar Street.
Akron, NY 14001
Dr. Kim Dietrich—University of Cincinnati College of Medicine, 3223 Eden Avenue,
Kettering Laboratory, Room G31, Cincinnati, OH 45267
Dr. Pam Factor-Litvak—Columbia University Mailman School of Public Health,
722 West 168th Street, Room 1614, New York, NY 10032
Dr. Vic Hasselblad—Duke University Medical Center, Durham, NC 27713
Dr. Stephen J. Rothenberg—CINVESTAV-IPN, Merida, Yucatan, Mexico & National Institute
of Public Health, Cuernavaca, Morelos, Mexico
Dr. Neal Simonsen—Louisiana State University Health Sciences Center, School of Public Health
& Stanley S Scott Cancer Center, 1600 Canal Street, Suite 800, New Orleans, LA 70112
Dr. Kyle Steenland—Rollins School of Public Health, Emory University, 1518 Clifton Road,
Room 268, Atlanta, GA 30322
Dr. Virginia Weaver—Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe
Street, Room 7041, Baltimore, MD 21205
Contributors and Reviewers
Dr. J. Michael Davis—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Lester D. Grant—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Kazuhiko Ito—Nelson Institute of Environmental Medicine, New York University School of
Medicine, Tuxedo, NY 10987
-------
Authors, Contributors, and Reviewers
(cont'd)
Contributors and Reviewers
(cont'd)
Dr. Kathryn Mahaffey—Office of Prevention, Pesticides and Toxic Substances,
U.S. Environmental Protection Agency, Washington, DC 20460
Dr. Karen Martin—Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Dr. Zachary Pekar—Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Ms. Beth Hassett-Sipple—Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Dr. John Vandenberg—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
CHAPTER 7 ANNEX (ENVIRONMENTAL EFFECTS OF LEAD)
Chapter Manager/Editor
Dr. Timothy Lewis—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Principle Authors
Dr. Ruth Hull—Cantox Environmental Inc., 1900 Minnesota Court, Suite 130, Mississauga,
Ontario, L5N 3C9 Canada
Dr. James Kaste—Department of Earth Sciences, Dartmouth College, 352 Main Street,
Hanover, NH 03755
Dr. John Drexler—Department of Geological Sciences, University of Colorado,
1216 Gillespie Drive, Boulder, CO 80305
Dr. Chris Johnson—Department of Civil and Environmental Engineering, Syracuse University,
365 Link Hall, Syracuse, NY 13244
Dr. William Stubblefield—Parametrix, Inc. 33972 Texas St. SW, Albany, OR 97321
II-xv
-------
Authors, Contributors, and Reviewers
(cont'd)
Principle Authors
(cont'd)
Dr. Dwayne Moore—Cantox Environmental, Inc., 1550ALaperriere Avenue, Suite 103,
Ottawa, Ontario, K1Z 7T2 Canada
Dr. David Mayfield—Parametrix, Inc., 411 108th Ave NE, Suite 1800, Bellevue, WA 98004
Dr. Barbara Southworth—Menzie-Cura & Associates, Inc., 8 Winchester Place, Suite 202,
Winchester, MA 01890
Dr. Katherine Von Stackleberg—Menzie-Cura & Associates, Inc., 8 Winchester Place,
Suite 202, Winchester, MA 01890
Contributors and Reviewers
Dr. Jerome Nriagu—Department of Environmental Health Sciences, 109 South Observatory,
University of Michigan, Ann Arbor, MI 48109
Dr. Judith Weis—Department of Biology, Rutgers University, Newark, NJ 07102
Dr. Sharon Harper—National Exposure Research Laboratory (D205-05), U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Dr. Karen Bradham—National Research Exposure Laboratory (D205-05), U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Dr. Ginger Tennant—Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Ms. Gail Lacey—Office of Air Quality Planning and Standards, U.S. Environmental Protection
Agency, Research Triangle Park, NC 27711
Dr. John Vandenberg—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
-------
U.S. Environmental Protection Agency Project Team
for Development of Air Quality Criteria for Lead
Executive Direction
Dr. Lester D. Grant (Director)—National Center for Environmental Assessment-RTF Division,
(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Scientific Staff
Dr. Lori White (Lead Team Leader)—National Center for Environmental Assessment
(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. James S. Brown—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Robert Elias—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (Retired)
Dr. Brooke Hemming—National Center for Environmental Assessment (B243-01), U.S.
Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Jee Young Kim—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Dennis Kotchmar—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Timothy Lewis—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Anuradha Muldipalli—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Srikanth Nadadur—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Paul Reinhart—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Mary Ross— National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. David Svendsgaard—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
-------
U.S. Environmental Protection Agency Project Team
for Development of Air Quality Criteria for Lead
(cont'd)
Technical Support Staff
Mr. Douglas B. Fennell—Technical Information Specialist, National Center for Environmental
Assessment (B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC
27711 (Retired)
Ms. Emily R. Lee—Management Analyst, National Center for Environmental Assessment
(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Ms. Diane H. Ray—Program Specialist, National Center for Environmental Assessment
(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Ms. Donna Wicker—Administrative Officer, National Center for Environmental Assessment
(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (Retired)
Mr. Richard Wilson—Clerk, National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Document Production Staff
Ms. Carolyn T. Perry—Task Order Manager, Computer Sciences Corporation, 2803 Slater Road,
Suite 220, Morrisville, NC 27560
Mr. John A. Bennett—Technical Information Specialist, Library Associates of Maryland,
11820 Parklawn Drive, Suite 400, Rockville, MD 20852
Mr. William Ellis—Records Management Technician, InfoPro, Inc., 8200 Greensboro Drive,
Suite 1450, McLean, VA 22102
Ms. Sandra L. Hughey—Technical Information Specialist, Library Associates of Maryland,
11820 Parklawn Drive, Suite 400, Rockville, MD 20852
Dr. Barbara Liljequist—Technical Editor, Computer Sciences Corporation, 2803 Slater Road,
Suite 220, Morrisville, NC 27560
Ms. Michelle Partridge-Doerr—Publications/Graphics Specialist, TEK Systems, 1201 Edwards
Mill Road, Suite 201, Raleigh, NC 27607
Mr. Carlton Witherspoon—Graphic Artist, Computer Sciences Corporation, 2803 Slater Road,
Suite 220, Morrisville, NC 27560
-------
U.S. Environmental Protection Agency
Science Advisory Board (SAB) Staff Office
Clean Air Scientific Advisory Committee (CASAC)
Chair
Dr. Rogene Henderson*—Scientist Emeritus, Lovelace Respiratory Research Institute,
Albuquerque, NM
Members
Dr. Joshua Cohen—Faculty, Center for the Evaluation of Value and Risk, Institute for Clinical
Research and Health Policy Studies, Tufts New England Medical Center, Boston, MA
Dr. Deborah Cory-Slechta—Director, University of Medicine and Dentistry of New Jersey and
Rutgers State University, Piscataway, NJ
Dr. Ellis Cowling*—University Distinguished Professor-at-Large, North Carolina State
University, Colleges of Natural Resources and Agriculture and Life Sciences, North Carolina
State University, Raleigh, NC
Dr. James D. Crapo [M.D.]*—Professor, Department of Medicine, National Jewish Medical and
Research Center, Denver, CO
Dr. Bruce Fowler—Assistant Director for Science, Division of Toxicology and Environmental
Medicine, Office of the Director, Agency for Toxic Substances and Disease Registry, U.S.
Centers for Disease Control and Prevention (ATSDR/CDC), Chamblee, GA
Dr. Andrew Friedland—Professor and Chair, Environmental Studies Program, Dartmouth
College, Hanover, NH
Dr. Robert Goyer [M.D.]—Emeritus Professor of Pathology, Faculty of Medicine, University of
Western Ontario (Canada), Chapel Hill, NC
Mr. Sean Hays—President, Summit Toxicology, Allenspark, CO
Dr. Bruce Lanphear [M.D.]—Sloan Professor of Children's Environmental Health, and the
Director of the Cincinnati Children's Environmental Health Center at Cincinnati Children's
Hospital Medical Center and the University of Cincinnati, Cincinnati, OH
Dr. Samuel Luoma—Senior Research Hydrologist, U.S. Geological Survey (USGS),
Menlo Park, CA
-------
U.S. Environmental Protection Agency
Science Advisory Board (SAB) Staff Office
Clean Air Scientific Advisory Committee (CASAC)
(cont'd)
Members
(cont'd)
Dr. Frederick J. Miller*—Consultant, Cary, NC
Dr. Paul Mushak—Principal, PB Associates, and Visiting Professor, Albert Einstein College of
Medicine (New York, NY), Durham, NC
Dr. Michael Newman—Professor of Marine Science, School of Marine Sciences, Virginia
Institute of Marine Science, College of William & Mary, Gloucester Point, VA
Mr. Richard L. Poirot*—Environmental Analyst, Air Pollution Control Division, Department of
Environmental Conservation, Vermont Agency of Natural Resources, Waterbury, VT
Dr. Michael Rabinowitz—Geochemist, Marine Biological Laboratory, Woods Hole, MA
Dr. Joel Schwartz—Professor, Environmental Health, Harvard University School of Public
Health, Boston, MA
Dr. Frank Speizer [M.D.]*—Edward Kass Professor of Medicine, Channing Laboratory,
Harvard Medical School, Boston, MA
Dr. Ian von Lindern—Senior Scientist, TerraGraphics Environmental Engineering, Inc.,
Moscow, ID
Dr. Barbara Zielinska*—Research Professor, Division of Atmospheric Science, Desert Research
Institute, Reno, NV
SCIENCE ADVISORY BOARD STAFF
Mr. Fred Butterfield—CASAC Designated Federal Officer, 1200 Pennsylvania Avenue, N.W.,
Washington, DC, 20460, Phone: 202-343-9994, Fax: 202-233-0643 (butterfield.fred@epa.gov)
(Physical/Courier/FedEx Address: Fred A. Butterfield, III, EPA Science Advisory Board Staff
Office (Mail Code 1400F), Woodies Building, 1025 F Street, N.W., Room 3604, Washington,
DC 20004, Telephone: 202-343-9994)
*Members of the statutory Clean Air Scientific Advisory Committee (CASAC) appointed by the
U.S. EPA Administrator
II-xx
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Abbreviations and Acronyms
aFGF
AA
AAL
AAS
ABA
ACBP
ACE
ACh
AChE
ACR
AD
ADC
ADP
AE
AEA
AFC
2-AG
A horizon
AHR
AI
ALA
ALAD
ALAS
ALAU
ALD
ALS
ALT
ALWT
AMEM
AMP
ANCOVA
ANF
Angll
a-fibroblast growth factor
arachidonic acid
active avoidance learning
atomic absorption spectroscopy
p-aminoisobutyric acid
Achenbach Child Behavior Profile
angiotensin converting enzyme
acetylcholine
acetylcholinesterase
acute-chronic ratio
adult
analog digital converter
adenosine diphosphate
anion exchange
TV-arachi dony 1 ethanol amine
antibody forming cells
2-arachidonylglycerol
uppermost layer of soil (litter and humus)
aryl hydrocarbon receptor
angiotensin I
*-aminolevulinic acid
*-aminolevulinic acid dehydratase
aminolevulinic acid synthetase
urinary 5-aminolevulinic acid
aldosterone
amyotrophic lateral sclerosis
alanine aminotransferase
albumin weight
Alpha Minimal Essential Medium
adenosine monophosphate
analysis of covariance
atrial natriuretic factor
angiotensin II
-------
ANOVA
ANP
AP
AP-1
ApoE
AQCD
Arg
AS52
ASGP-R
AST
ASV
3-AT
ATP
ATP1A2
ATPase
ATSDR
AVCD
AVS
AWQC
3
3FGF
173-HS
33-HSD
173-HSDH
63-OH-cortisol
B
BAEP
BAER
BAF
Bcell
BCFs
BCS
BDNF
BDWT
BEI
analysis of variance
atrial natriuretic peptide
alkaline phosphatase
activated protein-1
apolipoprotein E
Air Quality Criteria Document
arginine
cells derived from the CHO cell line
aceyl glycoprotein receptor
aspartate aminotransferase
anode stripping voltammetry
3-aminotriazole; 3-amino triazide
adenosine triphosphate
sodium-potassium adenosine triphosphase a2
adenosine triphosphatase
Agency for Toxic Substances and Disease Research
atrioventricular conduction deficit
acid volatile sulfide
ambient water quality criteria
beta-coefficient; slope of an equation
3-fibroblast growth factor
173-hydroxysteriod
33-hydroxysteriod dehydrogenase
173-hydroxysteriod dehydrogenase
6-3-hydroxycortisol
both
brainstem auditory-evoked potentials
brainstem auditory-evoked responses
bioaccumulation factor
B lymphocyte
bioconcentration factors
bovine calf serum
brain derived neurotrophic factor
body weight changes
biological exposure index
-------
BFU-E
BLL
BLM
BM
BMI
BDNF
BOTMP
BP
BPb
BSA
BSI
BTQ
BUN
bw, b. wt, BW
C3H10T/12
C3, C4
CA
CAS
45Ca
Ca-ATP
Ca-ATPase
CaCO3
CaEDTA
CAL
CaM
Ca-Mg-ATPase
cAMP
CaNa2 EDTA
CANTAB
CAT
CBCL
CBCL-T
CBL
CBLI
CCB
blood erythroid progenitor
blood lead level
biotic ligand model
basement membrane
body mass index
brain-derived neurotrophic factor
Bruinicks-Oseretsky Test of Motor Proficiency
blood pressure
blood lead concentration
bovine serum albumin
Brief Symptom Inventory
Boston Teacher Questionnaire
blood urea nitrogen
body weight
mouse embryo cell line
complement proteins
chromosome aberration
cornu ammonis 3 region of hippocampus
calcium-45 radionuclide
calcium-dependent adenosine triphosphate
calcium-dependent adenosine triphosphatase
calcium carbonate
calcium disodium ethylenediaminetetraacetic acid
calcitonin
calmodulin
calcium-magnesium-dependent adenosine triphosphatase
cyclic adenosinemonophosphate
calcium disodium ethylenediaminetetraacetic acid
Cambridge Neuropsychological Testing Automated Battery
catalase; Cognitive Abilities Test
Achenbach Child Behavior Checklist
Total Behavior Problem Score
cumulative blood lead
cumulative blood lead index
cytochalasin B
-------
CCD
CCE
CCL
CCS
Cd
109Cd
CdU
CEC
CESD, CES-D
GFAP
CFU-E
CFU-GEMM
CFU-GM
cGMP
ChAT
CHD
CHO
CI
CLE-SV
CLRTAP
CLS
CMC
CMI
CNS
COH
ConA
COR
CoTx
COX-2
CP
CPT
cr
CRAC
CREB
charge-coupled device
Coordination Center for Effects
carbon tetrachloride
cosmic calf serum
coefficient of component variance of respiratory sinus arrhythmia
cadmium
cadmium-109 radionuclide
urinary cadmium
cation exchange capacity
Center for Epidemiologic Studies Depression (scale)
glial fibrillary acidic protein
colony forming unit blood-erythroid progenitor (cell count)
colony forming unit blood-pluripotent progenitor (cell count)
blood granulocyte/macrophage progenitor (cell count)
cyclic guanosine-3',5'-monophosphate
choline acetyltransferase
coronary heart disease
Chinese hamster ovary cell line
confidence interval
competitive ligand-exchange/stripping voltammetry
Convention on Long-Range Transboundary of Air Pollution
Cincinnati Lead Study
criterion maximum concentration
cell-mediated immunity
central nervous system
cation-osmotic hemolysis
concanavalin A
cortisol
cotreatment
cyclooxygenase-2
coproporphryn
current perception threshold
creatinine
calcium release activated calcium reflux
cyclic AMP-response element binding protein
II-xxiv
-------
CRF
CRI
CSF
CuZn-SOD
CV
CVLT
CVR.R
CYP
CYPSall
D
DA
dbcAMP
DCV
DEAE
DET
DEYO
DPS
dfs
DG
DOT
DL
DMEM
DMEM/F12
DMFS
DMPS
DMSA
DMT
DMTU
DNA
DO
DOC
DOM
DOPAc
DPASV
dp/dt
chronic renal failure
chronic renal insufficiency
cerebrospinal fluid
copper and zinc-dependent superoxide dismutase
conduction velocity
California Verbal Learning Test
coefficient of variation of the R-R interval
cytochrome (e.g., CYP1A, CYP-2A6, CYP3A4, CYP450)
cytochrome P450 Sal 1
D-statistic
dopamine; dopaminergic
dibutyryl cyclic adenosine-3',5'-monophosphate
distribution of conduction velocities
diethylaminoethyl (chromatography)
diffusive equilibrium thin films
death of young
decayed or filled surfaces, permanent teeth
covariate-adjusted number of caries
dentate gyrus
diffusive gradient thin films
DL-statistic
Dulbecco's Minimal Essential Medium
Dulbecco's Minimal Essential Medium/Ham's F12
decayed, missing, or filled surfaces, permanent teeth
2,3-dimercaptopropane 1-sulfonate
2,3-dimercaptosuccinic acid
Donnan membrane technique
dimethylthiourea
deoxyribonucleic acid
distraction osteogenesis
dissolved organic carbon
dissolved organic carbon
3,4-dihydroxyphenylacetic acid
differential pulse anodic stripping voltammetry
rate of left ventricular isovolumetric pressure
II-XXV
-------
DPPD
DR
DSA
DTC
DTK
DTPA
DTT
dw
E
E2
EBE
EBV
EC
ECso
eCB
ECG
Eco-SSL
EDS
EDTA
EEDQ
EEG
EG
EGF
EGG
EGPN
EKG
electro
EM/CM
EMEM
eNOS
EP
EPA
Epi
EPMA
EPO
TV-TV-diphenyl-p-phynylene-diamine
drinking water
delayed spatial alternation
diethyl dithiocarbomate complex
delayed type hypersensitivity
diethylenetriaminepentaacetic acid
dithiothreitol
dry weight
embryonic day
estradiol
early biological effect
Epstein-Barr virus
European Community
effect concentration for 50% of test population
endocannabinoid
el ectrocardi ogram
ecological soil screening level
energy dispersive spectrometers
ethylenediaminetetraacetic acid
7V-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinone
el ectroencephal ogram
egg
epidermal growth factor
effects on eggs
egg production
el ectrocardi ogram
electrophysiological stimulation
experimental medium-to-control medium (ratio)
Eagle's Minimal Essential Medium
endothelial nitric oxide synthase
erythrocyte protoporphyrin
U.S. Environmental Protection Agency
epinephrine
electron probe microanalysis
erythropoietin
II-xxvi
-------
EPSC
EPT
ERG
ERL
ERM
EROD
ESCA
ESRD
EST
ESTH
ET
ETOH
EXAFS
EXANES
F
F344
FAV
FBS
FCS
FCV
FD
FEF
FEP
FERT
FEVi
FGF
FI
FIAM
FMLP
fMRI
FR
FSH
FT3
FT4
excitatory postsynaptic currents
macroinvertebrates from the Ephemeroptera (mayflies),
Plecoptera (stoneflies), and Trichoptera (caddisflies) group
electroretinogram; electroretinographic
effects range - low
effects range - median
ethoxyresorufin-0-deethylase
electron spectroscopy for chemical analysis
end-stage renal disease
estradiol
eggshell thinning
endothelein; essential tremor
ethyl alcohol
extended X-ray absorption fine structure
extended X-ray absorption near edge spectroscopy
F-statistic
Fischer 344 (rat)
final acute value
fetal bovine serum
fetal calf serum
final chronic value
food
forced expiratory flow
free erythrocyte protoporphyrin
fertility
forced expiratory volume in one second
fibroblast growth factor (e.g., PFGF, aFGF)
fixed interval (operant conditioning)
free ion activity model
N-f'ormy 1 -L-methi ony 1 -L-l eucy 1 -L-pheny 1 al anine
functional magnetic resonance imaging
fixed-ratio operant conditioning
follicle stimulating hormone
free triiodothyronine
free thyroxine
II-xxvii
-------
FTES
FTII
FTPLM
FURA-2
FVC
(-GT
G
GABA
GAG
G12 CHV79
GCI
GD
GDP
GEE
GFAAS
GFR
GGT
GH
GI
GIME-VIP
GIS
GLU
GMAV
GMCV
GMP
GMPH
GnRH
GOT
GP
G6PD, G6PDH
GPEI
gp91phox
GPT
GPx
free testosterone
Fagan Test of Infant Intelligence
flow-through permeation liquid membranes
l-[6-amino-2-(5-carboxy-2-oxazolyl)-5-benzofuranyloxy]-2-(2-
amino-5-methylphenoxy) ethane-7V,7V,jV',jV'-tetraacetic acid
forced vital capacity
(-glutamyl transferase
gestational day
gamma aminobutyric acid
glycosaminoglycan
cells derived from the V79 cell line
General Cognitive Index
gestational day
guanosine diphosphate
generalized estimating equations
graphite furnace atomic absorption spectroscopy
glomerular filtration rate
(-glutamyl transferase
growth hormone
gastrointestinal
gel integrated microelectrodes combined with voltammetric
in situ profiling
geographic information system
glutamate
genus mean acute value
genus mean chronic value
guanosine monophosphate
general morphology
gonadotropin releasing hormone
aspartate aminotransferase
gross productivity
glucose-6-phosphatedehydrogenase
glutathione S-transferase P enhancer element
NAD(P)H oxidase
glutamic-pyruvic transaminase
glutathione peroxidase
-------
GRO
GRP78
GSD
GSH
GSIM
GSSG
GST
GSTP
GTP
GV
H+
3H
HA
Hb
HBEF
HBSS
HCG; hCG
Hct
HDL
HEP
HET
HFPLM
Hgb
HGF
HH
H-H
HHANES
H-L
HLA
H-MEM
HMP
HNO3
H202
HOME
HOSTE
growth
glucose-regulated protein 78
geometric standard deviation
reduced glutathione
gill surface interaction model
glutathione disulfide
glutathione-^-transferase
placental glutathione transferase
guanosine triphosphate
gavage
acidity
hydrogen-3 radionuclide (tritium)
humic acid; hydroxyapatite
hemoglobin
Hubbard Brook Experimenatl Forest
Hank's Balanced Salt Solution
human chorionic gonadotropin
hematocrit
high-density lipoprotein (cholesterol)
habitat evaluation procedure
Binghamton heterogeneous stock
hollow fiber permeation liquid membranes
hemoglobin
hepatocyte growth factor
hydroxylamine hydrochloride
high-high
Hispanic Health and Nutrition Examination Survey
high-low
human leukocyte antigen
minimum essential medium/nutrient mixture-F12-Ham
hexose monophosphate shunt pathway
nitric acid
hydrogen peroxide
Home Observation for Measurement of Environment
human osteosarcoma cells
II-xxix
-------
HPLC
H3PO4
HPRT
HR
HSI
H2SO4
HSPG
Ht
HTC
hTERT
HTN
IBL
IBL H WRAT-R
ICD
ICP
ICP-AES
ICP-MS, ICPMS
ID-MS
IFN
Ig
IGF-1
IL
ILL
immuno
IMP
iNOS
i.p., IP
IPSC
IQ
IRT
ISEL
ISI
i.v., IV
IVCD
high-pressure liquid chromatography
phosphoric acid
hypoxanthine phosphoribosyltransferase (gene)
heart rate
habitat suitability indices
sulfuric acid
heparan sulfate proteoglycan
hematocrit
hepatoma cells
catalytic subunit of human telomerase
hypertension
integrated blood lead index
integrated blood lead index H Wide Range Achievement
Test-Revised (interaction)
International Classification of Diseases
inductively coupled plasma
inductively coupled plasma atomic emission spectroscopy
inductively coupled plasma mass spectrometry
isotope dilution mass spectrometry
interferon (e.g., IFN-Q
immunoglobulin (e.g., IgA, IgE, IgG, IgM)
insulin-like growth factor 1
interleukin (e.g., IL-1, IL-13, IL-4, IL-6, IL-12)
incipient lethal level
immunohistochemical staining
inosine monophosphate
inducible nitric oxide synthase
intraperitoneal
inhibitory postsynaptic currents
intelligence quotient
interresponse time
in situ end labeling
interstimulus interval
intravenous
intraventricular conduction deficit
II-XXX
-------
JV
KABC
KTEA
KXRF, K-XRF
LA
LB
LC
LCso
LD50
LDH
LDL
L-dopa
LE
LET
LH
LHRH
LN
L-NAME
LOAEL
LOEC
LOWES S
LPO
LPP
LPS
LT
LT50
LTER
LTP
LVH
liPIXE
liSXRF
MA
MA- 10
MANCOVA
juvenile
Kaufman Assessment Battery for Children
Kaufman Test of Educational Achievement
K-shell X-ray fluorescence
lipoic acid
laying bird
lactation
lethal concentration at which 50% of exposed animals die
lethal concentration at which 74% of exposed animals die
lethal dose at which 50% of exposed animals die
lactate dehydrogenase
low-density lipoprotein (cholesterol)
3,4-dihydroxyphenylalanine (precursor of dopamine)
Long Evans (rat)
linear energy transfer (radiation)
luteinizing hormone
luteinizing hormone releasing hormone
lead nitrate
L-7V°-nitroarginine methyl ester
lowest-observed adverse effect level
lowest-observed-effect concentration
locally weighted scatter plot smoother
lipoperoxide
lipid peroxidation potential
lipopolysaccharide
leukotriene
time to kill 50%
Long-Term Ecological Research (sites)
long term potentiation
left ventricular hypertrophy
microfocused particle induced X-ray emission
microfocused synchrotron-based X-ray fluorescence
mature
mouse Ley dig tumor cell line
multivariate analysis of covariance
II-xxxi
-------
MAO
MATC
MDA
MDA-TBA
MDCK
MDI
MDRD
MEM
MG
Mg-ATPase
MiADMSA
Mi-DMSA
MK-801
MLR
MMSE
MMTV
MN
MND
MNNG
MPH
MRI
mRNA
MROD
MRS
MS
MSCA
mSQGQs
MT
MVV
MW
N, n
N/A
NAAQS
NAC
NAD
monoamine oxidase
maximum acceptable threshold concentration
malondialdehyde
malondialdehyde-thiobarbituric acid
kidney epithelial cell line
Mental Development Index (score)
Modification of Diet in Renal Disease (study)
Minimal Essential Medium
microglobulin
magnesium-dependent adenosine triphosphatase
monoisamyl dimercaptosuccinic acid
mi monoisoamyl dimercaptosuccinic acid
NMD A receptor antagonist
mixed lymphocyte response
Mini-Mental State Examination
murine mammary tumor virus
micronuclei formation
motor neuron disease
7V-methyl-jV'-nitro-7V-nitrosoguanidine
morphology
magnetic resonance imaging
messenger ribonucleic acid
methoxyresorufm-O-demethylase
magnetic resonance spectroscopy
mass spectrometry
McCarthy Scales of Children's Abiltities
mean sediment quality guideline quotients
metallothionein
maximum voluntary ventilation
molecular weight (e.g., high-MW, low-MW)
number of observations
not available
National Ambient Air Quality Standards
TV-acetyl cysteine
nicotinamide adenine dinucleotide
II-xxxii
-------
NADH
NADP
NAD(P)H, NADPH
NADS
NAF
NAG
Na-K-ATPase
NAWQA
NET
NCBP
NCD
NCS
NCTB
NCV
ND
NDI
NE
NES
NF-KB
NGF
NHANES
NIOSH
NIST
NK
NMDA
NMDAR
NMR
NO
NO2
N03
NOAEC
NOAEL
NOEC
NOEL
NOM
reduced nicotinamide adenine dinucleotide
nicotinamide adenine dinucleotide phosphate
reduced nicotinamide adenine dinucleotide phosphate
nicotinamide adenine dinucleotide synthase
nafenopin
jV-acetyl-3-D-glucosaminidase
sodium-potassium-dependent adenosine triphosphatase
National Water-Quality Assessment
nitro blue tetrazolium
National Contaminant Biomonitoring Program
nuclear chromatin decondensation (rate)
newborn calf serum
Neurobehavioral Core Test Battery
nerve conduction velocity
non-detectable; not detected
nuclear divison index
norepinephrine
Neurobehavioral Evaluation System
nuclear transcription factor-KB
nerve growth factor
National Health and Nutrition Examination Survey
National Institute for Occupational Safety and Health
National Institute for Standards and Technology
natural killer
7V-methyl-D-aspartate
7V-methyl-D-aspartate receptor
nuclear magnetic resonance
nitric oxide
nitrogen dioxide
nitrate
no-observed-adverse-effect concentration
no-observed-adverse-effect level
no-observed-effect concentration
no-observed-effect level
natural organic matter
-------
NORs
NOS
NOX
NP
NPSH
NR
NRC
NRK
NS
NSAID
NT
NTA
02
ODVP
OH
7-OH-coumarin
1,25-OH-D, 1,25-OHD3
24,25-OH-D3
25-OH-D3
8-OHdG
O horizon
OR
OSWER
P,P
P300
P450 1A1
P450 1A2
P450CYP3all
PAD
PAH
PAI-1
PAR
Pb
203Pb
204pb 206pb 207pb 208pb
nucleolar organizing regions
nitric oxide synthase; not otherwise specified
nitrogen oxides
net productivity
nonprotein sulfhydryl
not reported
National Research Council
normal rat kidney
nonsignificant
non-steroidal anti-inflammatory agent
neurotrophin
nitrilotriacetic acid
oxygen
offspring development
hydroxyl
7-hydroxy-coumarin
1,25-dihydroxyvitamin D
24,25-dihydroxyvitamin D
25-hydroxyvitamin D
8-hydroxy-2'-deoxyguanosine
forest floor
odds ratio; other oral
Office of Solid Waste and Emergency Response
probability value
event-related potential
cytochrome P450 1A1
cytochrome P450 1A2
cytochrome P450 Sal 1
peripheral arterial disease
polycyclic aromatic hydrocarbon
plasminogen activator inhibitor-1
population attributable risk
lead
lead-203 radionuclide
stable isotopes of lead-204, -206, -207, -208, respectively
II-xxxiv
-------
Pb(Ac)2
PbB
PbCl2
Pb(ClO4)2
PBG-S
PBMC
Pb(N03)2
PbO
PBP
PbS
PbU
PC12
PCR
PCV
PDE
PDGF
PDI
PEC
PEF
PG
PHA
Pi
PIXE
PKC
plNEpi
PMA
PMN
PMR
PN
P5N
PND
p.o.,PO
POMS
lead-210 radionuclide
lead acetate
blood lead concentration
lead chloride
lead chlorate
porphobilinogen synthase
peripheral blood mononuclear cells
lead nitrate
lead oxides (or litharge)
progressive bulbar paresis
galena
urinary lead
pheochromocytoma cell
polymerase chain reaction
packed cell volume
phosphodiesterase
platelet-derived growth factor
Psychomotor Development Index
probable effect concentration
expiratory peak flow
prostaglandin (e.g., PGE2, PGF2); prostate gland
phytohemagglutinin A
inorganic phosphate
particle induced X-ray emission
protein kinase C
plasma norepinephrine
progressive muscular atrophy
polymorphonuclear leucocyte
proportionate mortality ratio
postnatal (day)
pyrimidine 5'-nucleotidase
postnatal day
per os (oral administration)
Profile of Mood States
parts per billion
II-xxxv
-------
ppm
PPVT-R
PRA
PRL
PROG
PRR
PRWT
PST
PTH
PTHrP
PVC
PWM
PRWT
QA/QC
Q/V
r
R2
r2
226Ra
R/ALAD
RAVLT
86Rb
RBA
RBC
RBF
RBP
RBPH
RCPM
REL
REP
RHIS
222Rn
RNA
ROS
ROS 17.2.8
parts per million
Peabody Picture Vocabulary Test-Revised
plasma renin activity
prolactin
progeny counts or numbers
prevalence rate ratio
progeny weight
percent transferrin saturation
parathyroid hormone
parathyroid hormone-related protein
polyvinyl chloride
pokeweed mitogen
progeny weight
quality assurance/quality control
flux of air (Q) divided by volume of culture (V)
Pearson correlation coefficient
multiple correlation coefficient
correlation coefficient
most stable isotope of radium
ratio of ALAD activity before and after reactivation
Rey Auditory Verbal Learning Test
rubidium-86 radionuclide
relative bioavailablity
red blood cell; erythrocyte
renal blood flow
retinol binding protein
reproductive behavior
Ravens Colored Progressive Matrices
rat epithelial (cells)
reproduction
reproductive organ histology
most stable isotope of radon
ribonucleic acid
reactive oxygen species
rat osteosarcoma cell line
II-xxxvi
-------
RPMI 1640 Roswell Park Memorial Institute basic cell culture medium
RR relative risk; rate ratio
RT reaction time
RSEM resorbed embryos
RSUC reproductive success (general)
RT reproductive tissue
ZSEM sum of the molar concentrations of simultaneously extracted metal
SA7 simian adenovirus
SAB Science Advisory Board
SAM ^-adenosyl-L-methionine
SBIS-4 Stanford-Binet Intelligence Scale-4th edition
s.c., SC subcutaneous
SCAN Test for Auditory Processing Disorders
SCE selective chemical extraction; sister chromatid exchange
SCP stripping chronopotentiometry
SD Spraque-Dawley (rat); standard deviation
SDH succinic acid dehydrogenase
SDS sodium dodecyl sulfate; Symbol Digit Substitution
SE standard error; standard estimation
SEM standard error of the mean
SES socioeconomic status
sGC soluble guanylate cyclase
SH sulfhydryl
SHBG sex hormone binding globulin
SHE Syrian hamster embryo cell line
SIMS secondary ion mass spectrometry
SIR standardized incidence ratio
SLP synthetic leaching procedure
SM sexually mature
SMAV species mean acute value
SMR standardized mortality ratio
SNAP Schneider Neonatal Assessment for Primates
SNP sodium nitroprusside
SO2 sulfur dioxide
SOD superoxide dismutase
II-xxxvii
-------
SOPR
SPCL
SPCV
SQGs
SRA
SRD
SRIF
SRM
SRT
SSADMF
SSB
SSEP
StAR
STORE!
SVC
SVRT
T
TA
TABL
T&E
TAT
TB
TEARS
TBPS
TCDD
Tcell
TCLP
TE
TEC
TEDG
TEL
TES
TEWT
TF
TG
sperm-oocyte penetration rate
sperm cell counts
sperm cell viability
sediment quality guidelines
Self Reported Antisocial Behavior scale
Self Report of Delinquent Behavior
somatostatin
Standard Reference Material
simple reaction time
Social Security Administration Death Master File
single-strand breaks
somatosensory-evoked potential
steroidogenic acute regulatory protein
STOrage and RETrieval
sensory conduction velocity
simple visual reaction time
testosterone
tail
time-averaged blood lead
threatened and endangered (species)
tyrosine aminotransferase
tibia
thiobarbituric acid-reactive species
Total Behavior Problem Score
methionine-choline-deficient diet
T lymphocyte
toxic characteristic leaching procedure
testes
threshold effect concentration
testes degeneration
tetraethyl lead
testosterone
testes weight
transferrin, translocation factor
6-thioguanine
II-xxxviii
-------
TGF
TH
232^
TLC
TNF
TOP
tPA
TPRD
TRH
TRY
TSH
TSP
TT3
TT4
TIES
TTR
TU
TWA
TX
U
235U, 238U
UCP
UDP
UNECE
Ur
USFWS
USGS
UV
V79
VA
vc
VDR
VE
VEP
VI
transforming growth factor
tyrosine hydroxylase
stable isotope of thorium-232
Treatment of Lead-exposed Children (study)
tumor necrosis factor (e.g., TNF-a)
time-of-flight
plasminogen activator
total production
thyroid releasing hormone
toxicity reference value
thyroid stimulating hormone
triple-super phosphate
total triiodothyronine
serum total thyroxine
total testosterone
transthyretin
toxic unit
time-weighted average
tromboxane (e.g., TXB2)
uriniary
uranium-234 and -238 radionuclides
urinary coproporphyrin
uridine diphosphate
United Nations Economic Commission for Europe
urinary
U.S. Fish and Wildlife Service
United States Geological Survey
ultraviolet
Chinese hamster lung cell line
Veterans Administration
vital capacity; vitamin C
vitamin D receptor
vitamin E
visual-evoked potential
variable-interval
II-xxxix
-------
vitC
vitE
VMA
VMI
VSM
VSMC
WAIS
WDS
WHO
wise
WISC-R
WO
WRAT-R
WT
WTHBF-6
ww
XAFS
XANES
XAS
XPS
X-rays
XRD
XRF
ZAP
ZnNa2 DTPA
ZnNa2 EDTA
ZPP
vitamin C
vitamin E
vanilmandelic acid
Visual-Motor Integration
vascular smooth muscle (cells)
vascular smooth muscle cells
Wechsler Adult Intelligence Scale
wavelength dispersive spectrometers
World Health Organization
Wechsler Intelligence Scale for Children
Wechsler Intelligence Scale for Children-Revised
whole organism
Wide Range Achievement Test-Revised
wild type
human liver cell line
wet weight
X-ray absorption fine structure
X-ray absorption near edge spectroscopy
X-ray absorption spectroscopy
X-ray photoelectron spectroscopy
synchrotron radiation
X-ray diffraction
X-ray fluorescence
correction in reference to three components of matrix effects:
atomic number (Z), absorption (A), and fluorescence (F)
zinc disodium diethylenetriaminepentaacetic acid
zinc disodium ethylenediaminetetraacetic acid
zinc protoporphyrin
II-xl
-------
AX6. CHAPTER 6 ANNEX
AX6-1
-------
ANNEX TABLES AX6-2
AX6-2
-------
Table AX6-2.1. Prospective Longitudinal Cohort Studies of Neurocognitive Ability in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States
Bellinger etal. (1992)
U.S.
Dietrich et al.
(1991, 1992, 1993a);
Ris et al. (2004)
U.S.
X
Canfield et al. (2003a)
U.S.
148 subjects from the Boston Prospective Study
were re-evaluated at 10 yrs of age. The WISCR
was used to index intellectual status. Extensive
assessment of medical and sociodemographic
covariates.
253-260 children followed since birth in the
Cincinnati Pb Study were re-evaluated at 4, 5, and
6.5 yrs of age. At 4 and 5 yrs, the KABC was used
to index intellectual status. At 6.5 yrs, the WISCR
was administered. At 15-17 yrs of age, 195
Cincinnati Pb Study subjects were re-evaluated by
use of a comprehensive neuropsychological battery
that yielded a "Learning/IQ" factor in a principal
components analysis. Extensive assessment of
medical and sociodemographic covariates.
172 predominantly African-American, lower
socioeconomic status children in Rochester, NY
followed since they were 5 to 7 mos were evaluated
at 3 and 5 yrs. An abbreviated form of the
Stanford-Binet Intelligence Scale-4 (SBIS-4) was
used to index intellectual status. Extensive
assessment of medical and sociodemographic
covariates.
Cord and serial postnatal
blood Pb assessments
Cord blood Pb grouping <3,
6-7, >10 ug/dL
Blood Pb at 2 yrs 6.5
(SD 4.9) ug/dL
Prenatal (maternal) and serial
postnatal blood Pb
assessments
Prenatal blood Pb 8.3
(SD 3.7) ug/dL
Blood Pb at 2 yrs 17.4
(SD 8.8) ug/dL
Serial postnatal blood Pb
Blood Pb at 2 yrs
9.7 ug/dL
Increase of 10 ug/dL in blood Pb level at age two was
associated with a decrement of ~6 IQ points. Relationship
was stronger for verbal compared to performance IQ.
Prenatal exposure to Pb as indexed by cord blood Pb levels
was unrelated to psychometric intelligence.
Few statistically significant relationships between blood Pb
indices and covariate-adjusted KABC scales at 4 and 5 yrs
of age. One KABC subscale that assesses visual-spatial
skills was associated with late postnatal blood Pb levels
following covariate adjustment. After covariate
adjustment, avg postnatal blood Pb level was significantly
associated with WISCR performance IQ at 6.5 yrs. Blood
Pb concentrations >20 ug/dL were associated with deficits
in performance IQ on the order of 7 points compared with
children with mean blood Pb concentrations < 10 ug/dL.
At 15-17 yrs, late childhood blood Pb levels were
significantly associated with lower covariate-adjusted
Leaming/IQ factor scores.
Following covariate adjustment, there was a significant
inverse relationship between blood Pb indices and IQ at all
ages. Overall estimate indicated that an increase in avg
lifetime blood Pb concentration of 1 ug/dL was associated
with a loss of Vi IQ point. Effects were stronger for
subjects whose blood Pb levels never exceeded 10 ug/dL.
Semiparametric analysis indicated a decline in IQ of 7.4
points for a lifetime avg blood Pb concentration up to
10 ug/dL, while for levels between 10 and 30 ug/dL a
more gradual decrease in IQ was estimated. Authors
concluded that the most important aspect of their findings
was that effects below 10 ug/dL observed in previous
cross-sectional studies have now been confirmed by this
rigorous prospective study.
-------
Table AX6-2.1 (cont'd). Prospective Longitudinal Cohort Studies of Neurocognitive Ability in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
X
-k
United States (cont'd)
Bellinger and
Needleman (2003)
U.S.
Chen et al. (2005)
U.S.
Reanalysis of data from the Boston Prospective
Study focusing on 48 subjects at 10 yrs of age
whose blood Pb levels never exceeded 10 ug/dL.
WISCR was used to index intellectual status. See
also Bellinger etal. (1992)
Repeat measure psychometric data on 780 children
enrolled in Treatment of Pb-Exposed Children
(TLC) clinical trial were analyzed to determine if
blood Pb concentrations at 2 yrs of age constitute a
critical period of exposure for expression of later
neurodevelopmental deficits. Data for placebo and
active drug groups were combined in these
analyses, which spanned ~2 to 7 yrs of age.
Measures of intellectual status included the Bayley
Mental Development Index (MDI) and full scale IQ
derived from age-appropriate Wechsler scales.
Serial postnatal blood Pb
Blood Pb at 2 yrs 6.5
(SD 4.9) ug/dL
Blood Pb
Range 20-44 ug/dL
Baseline blood Pb 26
(SD 26.5) ug/dL in both drug
and placebo groups
Blood Pb at 7 yrs 8.0
(SD 4.0) ug/dL
IQ was inversely related to two-yr blood Pb levels
following covariate adjustment. Blood Pb coefficient
(! 1.56) was greater than that derived from analyses
including children with concentrations above 10 ug/dL
(!0.58). Authors conclude that children's IQ scores are
reduced at Pb levels still prevalent in U.S.
Association between blood Pb and psychometric
intelligence increased in strength as children became older,
whereas the relation between baseline (2 yr) blood Pb and
IQ attenuated. Peak blood Pb concentration thus does not
fully account for the observed association in older children
between their lower blood Pb concentrations and IQ. The
effect of concurrent blood Pb on IQ may thusly be greater
than currently believed. Authors conclude that these data
(a) support the idea that Pb exposure continues to be toxic
to children as they reach school age and (b) do not lend
support to the interpretation that majority of the damage is
done by the time the child reaches 2 to 3 yrs of age.
-------
Table AX6-2.1 (cont'd). Prospective Longitudinal Cohort Studies of Neurocognitive Ability in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Europe
Wasserman et al. (1992,
1994, 2003); Factor-
Litvaketal. (1999)
Yugoslavia
X
Birth cohort of-300-400 infants followed since
birth residing in two towns in Kosovo, Yugoslavia,
one group near a longstanding Pb smelter and
battery manufacturing facility and another in a
relatively unexposed location 25 miles away.
Intellectual status was monitored from 2 to
10-12 yrs of age with the Bayley Scales of Infant
Development, McCarthy Scales of Children's
Abilities, and WISCIII. Extensive assessment of
medical and sociodemographic covariates.
Maternal prenatal, umbilical
cord, and serial postnatal
blood Pb
Maternal blood Pb in exposed
area 19.9 (SD 7.7) ug/dL,
unexposed area 5.6 (SD 2.0)
ug/dL
Umbilical cord blood Pb in
exposed area 22.2 (SD 8.1)
ug/dL, unexposed area 5.5
(SD 3.3) ug/dL
Blood Pb at 2 yrs in
exposed area 35.4 ug/dL,
unexposed area 8.5 ug/dL
Postnatal blood Pb increment from 10 to 30 ug/dL at 2 yrs
of age associated with covariate-adjusted decline of 2.5
points in Bayley MDI. Maternal and cord blood Pb not
consistently associated with Bayley outcomes. Higher
prenatal and cord blood Pb concentrations associated with
lower McCarthy General Cognitive Index (GCI) scores at
4 yrs. Scores on the Perceptual-Performance subscale
particularly affected. After covariate-adjustment, children
of mothers with prenatal blood Pb levels >20 ug/dL scored
a full standard deviation below children in the lowest
exposure group (<5 ug/dL prenatal blood Pb). Postnatal
blood Pb also associated with poorer performance.
Increase in blood Pb level from 10 to 25 ug/dL associated
with a reduction of 3.8 points in GCI after covariate-
adjustment. Effects even more pronounced on the
Perceptual-Performance subscale. At 7 yrs, significant
inverse associations between lifetime avg blood Pb and
WISCIII IQ were observed, including consistently stronger
associations with Performance IQ and later blood Pb
measures. Adjusted intellectual loss associated with an
increase in lifetime avg blood Pb from 10 to 30 ug/dL was
over 4 points in WISCIII Full-Scale and Performance IQ.
At 10-12 yrs, subjects were again assessed with the
WISCIII. Following covariate-adjustment, avg lifetime
blood Pb was associated with all components of the
WISCIII, with effect sizes similar to those observed at
7 yrs. In most instances, bone Pb-IQ relationships were
stronger than those for blood Pb among subjects residing
near the Pb smelter.
-------
Table AX6-2.1 (cont'd). Prospective Longitudinal Cohort Studies of Neurocognitive Ability in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Latin America
Schnaas et al. (2000)
Mexico
Schnaas et al. (2006)
Mexico
X
Oi
Gomaa et al. (2002)
Mexico
112 children followed since birth with complete
psychometric data from the Mexico City
Prospective Study were examined. Intellectual
status indexed by General Cognitive Index (GCI)
from McCarthy Scales of Children's Abilities
(MSCA). Purpose of the study was to determine if
magnitude of the effect of postnatal blood Pb levels
on cognition varies with time between blood Pb
and cognitive assessments.
From the Mexico City Prospective Study, 150
children followed since birth with complete data
for all covariates were examined. Intelligence from
age 6 to 10 yrs was assessed using the WISC-R.
Blood Pb measurements from various time points,
starting from maternal blood Pb levels during the
2nd trimester to postnatal Pb levels at age 10 yrs.
197 two yr-old children residing in Mexico City
followed since birth. Bay ley Scales of Infant
Development Mental Development Index (MDI)
used to index intellectual status. Extensive
assessment of medical and sociodemographic
covariates.
Serial postnatal blood Pb
Avg blood Pb
24-36 mos 9.7
(range 3-48) ug/dL
Serial prenatal (maternal) and
postnatal blood Pb
Geometric mean blood Pb
During pregnancy 8.0
(range 1-33) ug/dL
Age 1-5 yrs 9.8
(range 2.8-36.4) ug/dL
Age 6-10 yrs 6.2
(range 2.2-18.6) ug/dL
Umbilical cord and serial
postnatal blood Pb
Umbilical cord blood
Pb 6.7 (SD 3.4) ug/dL
Blood Pb at 2 yrs 8.4
(SD 4.6) ug/dL
Maternal tibial and patellar
bone Pb
Patellar (trabecular)
bone Pb 17.9 (SD 15.2) ug/g
A number of significant interactions observed between
blood Pb levels and age of assessment. Greatest effect
observed at 48 mos, when a 5.8 deficit in adjusted GCI
scores was observed for each natural log increment in
blood Pb. Authors concluded that four to five yrs of age
appears to be a critical period for manifestation of earlier
postnatal blood Pb level effects on cognition.
Among all the Pb variables at the various time points, only
log-transformed blood Pb levels during the 3rd trimester
were significantly associated with full scale IQ at ages 6 to
10 yrs, after adjusting for potential confounders. A 3.44
point deficit in full scale IQ was observed for each natural
log increment in blood Pb.
The authors note that, given the modest sample size and
relatively low power of this study, they do not claim that
Pb exposure from other developmental period has no effect
on child IQ.
Umbilical cord blood Pb and patellar (trabecular) bone Pb
significantly associated with lower Bayley MDI scores.
Maternal trabecular bone Pb levels predicted poorer
sensorimotor functioning at two yrs independent of
concentration Pb measured in cord blood. Increase in cord
blood Pb level from 5 to 10 ug/dL was associated with a
3.1 point decrement in adjusted MDI scores. In relation to
lowest quartile of trabecular bone Pb, the 2nd, 3rd, and 4th
quartiles were associated with 5.4, 7.2, and 6.5 decrement
in MDI following covariate adjustment. Authors
concluded that higher maternal trabecular bone Pb levels
constitute an independent risk factor for impaired mental
development in infancy, likely due to the mobilization of
maternal bone Pb stores over gestation.
-------
Table AX6-2.1 (cont'd). Prospective Longitudinal Cohort Studies of Neurocognitive Ability in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Latin America (cont'd)
Tellez-Rojo et al.
(2006)
Mexico
294 one and two yr-olds residing in Mexico City
followed since birth. The Bay ley Scales of Infant
Development-II (MDI and PDI) were used to index
developmental status. There was extensive
assessment of medical and sociodemographic
covariates.
Umbilical cord blood Pb and
postnatal blood Pb at 12 and
24mos
Umbilical cord blood Pb 4.8
(SD 3.0) ug/dL
Blood Pb at lyr 4.27 (SD
2.1)ng/dL
BloodPbat2yrs4.3(SD
2.2) ng/dL
X
Blood Pb at 12 mos was not associated with MDI at either
age. Blood Pb at 24 mos was significantly associated with
24 mo MDI. An increase of one logarithmic unit in 24 mo
blood Pb level was associated with a reduction of ~5 points
in MDI. Findings for PDI were similar. In comparison to
a supplemental subsample of 90 subjects with blood Pb
levels >10 ug/dL, the coefficient for blood Pb was
significantly larger for infants never exceeding that level
of internal dose. A steeper inverse slope was observed
over the blood Pb range up to 5 ug/dL (! 1.71 points per
1 ug/dL increase in blood Pb, p = 0.01) compared to the
range between 5 and 10 ug/dL (10.94 points, p = 0.12);
however, these slopes were not significantly different
(p = 0.34). In conclusion, a major finding of this
prospective study was that a significant inverse
relationship between blood Pb concentration and
neurodevelopment was observed among children whose
blood Pb levels did not exceed 10 ug/dL at any age.
Australia
Baghurst et al. (1992);
McMichael et al.
(1994); long etal.
(1996)
Australia
400-500 subjects residing in and near Port Pirie,
Australia and followed since birth were re-evaluated
at 7 to 8 and 11 -13 yrs of age. WISCR was used to
index intellectual status at both ages. Extensive
assessment of medical and sociodemographic
covariates.
Maternal prenatal, umbilical
cord and serial postnatal blood
Pb
Antenatal avg blood Pb
10.1 (SD 3.9) ug/dL
Umbilical cord blood Pb
9.4 (SD 3.9) ug/dL
Blood Pb at 2 yrs
geometric mean 21.3
(SD 1.2) ug/dL
Deciduous central incisor
whole tooth Pb
Tooth Pb geometric 8.8
(SD1.9)ug/g
Significant decrements in covariate-adjusted full scale IQ
were observed in relationship to postnatal blood Pb levels
at both ages. At 7 to 8 yrs of age a loss of 5.3 points was
associated with an increase in blood Pb from 10 to
30 ug/dL. At 11-13 yrs, mean full scale IQ declined by 3.0
points for an increase in lifetime avg blood Pb
concentrations from 10 to 20 ug/dL. Pb levels in central
upper incisors were also associated with lower 7-8 yr IQ
following covariate adjustment. Adjusted estimated
decline in IQ across the range of tooth Pb from 3 to
22 ppm was 5.1 points.
-------
Table AX6-2.1 (cont'd). Prospective Longitudinal Cohort Studies of Neurocognitive Ability in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Australia (cont'd)
Cooneyetal. (1991)
Australia
175 subjects from the Sydney, Australia Prospective
Study were assessed at 7 yrs of age. The WISCR
was used to index intellectual status. Extensive
assessment of medical and sociodemographic
characteristics.
Maternal and cord blood Pb
Cord blood Pb 8.4 ug/dL
(SD not given)
Blood Pb at 2 yr 15.8 ug/dL
(SD not given)
Blood indices of Pb exposure were not associated with any
measure of psychometric intelligence. Authors conclude
that the evidence from their study indicates that if
developmental deficits do occur at blood Pb levels
<25 ug/dL, the effect size is likely to be small (<5%).
Sydney results are difficult to interpret from the statistical
presentation in their report. It is not clear which covariates
were entered into regression analyses nor is the empirical
or substantive basis for their conclusion.
Asia
Shenetal. (1998)
China
X
oo
Pregnant women and newborns in Shanghai, China
recruited from health care facilities in the community
on the basis of cord blood Pb concentration
percentiles (30th and 70th) yielding a total N of 173
subjects. TheBayley Scales of Infant Development
Mental Development Index (MDI) and Psychomotor
Development Index (PDI) were used to index
sensorimotor/intellectual status at 3, 6, and 12 mos.
Extensive assessment of medical and
sociodemographic characteristics.
Cord blood Pb
"High group" 13.4 (SD 2.0)
ug/dL
"Low group" 5.3 (SD 1.4)
ug/dL
Blood Pb at 1 yr
"High group" 14.9 (SD 8.7)
ug/dL
"Low group" 14.4 (SD 7.7)
ug/dL
At all ages the Bayley MDI was associated with cord
blood Pb groupings following adjustment for covariates.
Postnatal blood Pb unrelated to any Bayley measures.
Differences in MDI between prenatal blood Pb exposure
groupings generally in accord with similar investigations
in Boston, Cincinnati, and Cleveland. Authors conclude
that the adverse effects of prenatal Pb exposure are readily
discernible and stable over the first yr of life.
-------
Table AX6-2.2. Meta- and Pooled-Analyses of Neurocognitive Ability in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Lanphear et al. (2005)
X
Needleman and
Gatsonis(1990)
Pooled analysis of seven international prospective
studies involving 1,333 school-age children.
Primary outcome measure was full-scale IQ as
assessed by age-appropriate Wechsler scale.
Measures of exposure were concurrent, peak, avg
lifetime and "early" blood Pb (i.e. mean blood Pb
from 6-24 mos). Cord blood Pb was also
investigated for those studies that collected these
samples at birth. Multivariate regression models
were developed adjusting for site as well as 10
common covariates. Blood Pb measure with the
largest adjusted R2 was nominated a priori as the
preferred index for relating Pb exposure to IQ in
subsequent analyses. Results evaluated by applying
a random-effects model.
Meta analysis of 12 studies chosen on the basis of
quality—covariate assessment and application of
multiple regression techniques. Studies weighted on
basis of sample size. Studies divided according to
tissue analyzed (blood or teeth). Joint p-values and
avg effect sizes calculated using two different
methods.
Umbilical cord blood Pb
Serial postnatal blood Pb
Lifetime avg blood Pb 12.4
(range 4.1-34.8) ug/dL
Blood Pb
Tooth Pb
Concurrent blood Pb level exhibited the strongest
relationship with IQ, although results of regression analyses
for all blood Pb variables were similar. Steepest declines in
IQ were at blood Pb concentrations below 10 ug/dL. For
the entire pooled data set, a decline of 6.2 IQ points (95%
CI: 3.8, 8.6) was estimated for an increment in blood Pb
from 1 to 10 ug/dL.
Joint p-values for blood Pb studies were <0.0001 for both
methods, whereas joint p-values of <0.0006 and <0.004
were obtained for teeth. Partial correlations ranged from
-0.27 to -0.0003. No single study was responsible for the
significance of the final findings. Authors concluded that
the hypothesis that Pb lowers children's IQ at relatively low
dose is strongly supported by results of this quantitative
Schwartz (1994) Meta analysis of 7 recent studies relating blood Pb to
IQ were reviewed, three longitudinal and four cross-
sectional. Measure of effect was estimated decrease
in IQ for an increase in blood Pb from 10 to 20
ug/dL. Studies were weighted by the inverse of the
variances using random
Blood Pb
Estimated decrease in IQ per blood Pb increment from 10 to
20 ug/dL was -2.6 points (SE 0.41). Results were not
determined by any individual study. Effect estimates were
similar for longitudinal and cross-sectional studies.
For studies with mean blood Pb levels <15 ug/dL, estimated
effect sizes were larger. When the study with the lowest
exposures was examined alone using nonparametric
smoothing (Boston), no evidence of a threshold was
observed down to a blood Pb level of 1 ug/dL. Author
concludes that these data provide further evidence of Pb
effects on cognition at levels below 10 ug/dL.
-------
Table AX6-2.2 (cont'd). Meta- and Pooled-Analyses of Neurocognitive Ability in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Pococketal. (1994)
Meta-analysis of five prospective and fourteen cross-
sectional studies (including tooth and blood tissues)
were included. The fixed effect method of
Thompson and Pocock (1992) was employed.
Only blood Pb at or near two yrs of age was
considered for the prospective studies.
Blood Pb
Tooth Pb
Overall conclusion was that a doubling of blood Pb levels
from 10 to 20 |ig/dL, or tooth Pb from 5 to 10 jig/g was
associated with an avg estimated deficit in IQ of-1-2
points. Authors caution interpretation of these results and
Pb literature in general, citing questions about
representativeness of the samples, residual confounding,
selection bias, and reverse causality.
X
-------
Table AX6-2.3. Cross-Sectional Studies of Neurocognitive Ability in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
X
United States
Lanphear et al. (2000)
U.S.
Emory et al. (2003)
U.S.
Chiodo et al. (2004)
U.S.
4,853 U.S. children ages six to 16 yrs enrolled in
NHANES-III. Two subtests of the WISC-R (Block
Design and Digit Span) used to assess intellectual
status. Medical and sociodemographic covariates were
assessed
77 healthy, lower-risk African-American infants age 7
mos. The Fagan Test of Infant Intelligence (FTII) was
administered to assess intellectual status. Birth weight
and gestational age examined as potential
covariates/confounders.
237 African-American inner-city children assessed at
7.5 yrs of age. Cohort was derived from a larger study
of the effects of prenatal alcohol exposure on child
development. 83% of children in Pb study had little or
no gestational exposure to alcohol. WISC-III was
administered to assess intellectual status. Medical and
sociodemographic covariates were assessed.
Blood Pb at time of testing
Geometric blood Pb 1.9
(SE 0.1) ug/dL
2.1% with blood Pb
310 ug/dL
Maternal blood Pb
Blood Pb 0.72 (SD 0.5
ug/dL
Blood Pb at time of testing
BloodPb5.4(SD3.3)
ug/dL
Multivariate analyses revealed a significant association
between blood Pb levels and both WISC-R subtests.
Associations remained statistically significant when
analyses were restricted to children with blood Pb levels
below 10 ug/dL. Authors caution that lack of control for
parental intelligence and variables like the HOME scale
should temper any conclusions regarding observed effects.
Infants scoring in the upper 5th to 15th percentiles for the
FTII had mother with significantly lower maternal blood
Pb levels when compared to those scoring in the lower
5th or 15th percentile. Findings of this study should be
considered preliminary due to small sample size and lack
of covariate assessment or control.
Following covariate adjustment statistically significant
relationships between blood Pb and full-scale, verbal and
performance IQ were observed. Significant effects of Pb
on full-scale and performance IQ was evident at blood Pb
concentrations below 7.5 ug/dL.
Europe
Walkowiak et al.
(1998)
Germany
Prpic-Majic et al.
(2000)
Croatia
384 six-yr-old children in three German cities. Two
subtests of the WISC (Vocabulary and Block Design)
used to estimate IQ. Both subscales were combined to
form a "WISC Index." Medical and sociodemographic
covariate covariates were assessed.
275 3rd and 4th grade students in Zagreb, Croatia.
WISC-R was administered to assess intellectual status.
Covariate factors limited to parents' educational status
and gender of child.
Blood Pb at time of testing
Blood Pb 4.2 ug/dL
95th percentile 8.9 ug/dL
Blood Pb at time of testing
BloodPb7.1(SD1.8)
ug/dL
Following covariate-adjustment, WISC Vocabulary was
significantly associated with blood Pb but combined WISC
index was borderline. Authors conclude that findings
roughly correspond with those of other studies that find
effects below 10 ug/dL but caution that potentially
important covariates such as HOME scores were not
controlled.
Following covariate adjustment, no statistically significant
associations were observed for Pb or other indicators of
toxicity (ALAD, EP) on WISC-R. Authors argue that
study had sufficient power and that the "no-effect"
threshold for Pb must be in the upper part or above the
study's range of exposures.
-------
Table AX6-2.3 (cont'd). Cross-Sectional Studies of Neurocognitive Ability in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Latin America
Kordas et al. (2004,
2006)
Mexico
602 1 st grade children in public schools in a highly
industrialized area of northern Mexico. Premise of
study was that effects of Pb could be explained by
correlated nutritional factors such as iron status,
anemia, and growth. Peabody Picture Vocabulary
Test-Revised (PPVT-R), Cognitive Abilities Test
(CAT), and an abbreviated form of the WISC-R were
administered to assess intellectual status. Medical and
sociodemographic covariates were assessed.
Blood Pb at time of testing
Blood Pbl 1.5
(SD 6.1) ug/dL
X
to
Counter etal. (1998)
Ecuador
77 chronically Pb-exposed children living in
Ecuadorian villages where Pb is used extensively in
commercial ceramics production. Ravens Colored
Progressive Matrices (RCPM) used to index
intellectual status. Only half of the sample was
assessed. No assessment of medical or
sociodemographic covariates.
Blood Pb at time of testing
Blood Pb 47.4 (SD 22)
ug/dL
Following covariate adjustment blood Pb levels were
significantly associated with poorer performance on the
PPVT-R, WISC-R Coding, and Number and Letter
Sequencing, a Math Achievement Test, and the Sternberg
Memory Test. Authors concluded that Pb's association
with iron deficiency anemia or growth retardation could
not explain relationship between Pb and cognitive
performance. Non-linear analyses of selected
neurocognitive outcomes revealed that dose-response
curves were steeper at lower than at higher blood Pb
levels. Moreover, the slopes appeared negative at blood
Pb levels below 10 ug/dL, above which they tend to
plateau. Effects of Pb on neurocognitive attainment
appeared to be greatest among the least advantaged
members of the cohort.
Simple regression analysis revealed a correlation between
blood Pb and RCPM of only borderline significance.
Results difficult to interpret because there was no attempt
to age-adjust. When analysis restricted to children 9 to
11 yrs of age, a highly significant negative correlation was
obtained. Study has little relevance to the question of Pb
hazards in the U.S. because of unusually high levels of
exposure.
Asia
Rabinowitz et al.
(1991)
Taiwan
Bellinger et al. (2005)
India
443 children in grades one to three in Taipei City and
three schools near Pb smelters. Ravens Colored
Progressive Matrices (RCPM) used to index
intellectual status. Medical and sociodemographic
covariate factors were assessed.
74 four to fourteen yr-old children residing in Chennai,
India were enrolled in the study, 31 of which were
assessed with the Binet-Kamath Intelligence test. Data
were collected on sociodemographic features of
subjects' families.
Dentin tooth Pb
Taipei City 4.3 (SD 3. 7)
ug/g
Smelter areas 6. 3 (SD 3. 3)
Blood Pb at time of testing
Blood Pb 11. 1(SD 5.6)
ug/dL
Scores on the RCPM were negatively correlated with tooth
Pb concentrations. In multivariate analyses, parental
education was the most important predictor of RCPM
scores, but tooth Pb concentrations still significantly
predicted lower scores in females residing in low-income
families.
Covariate-adjusted blood Pb coefficient was negative but
nonsignificant, perhaps due to small sample size and
highly variable performance of subjects with the least
elevated blood Pb concentrations.
-------
Table AX6-2.3 (cont'd). Cross-Sectional Studies of Neurocognitive Ability in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Middle East
Al-Salehetal. (2001)
Saudi Arabia
533 Riyadh, Saudi Arabian girls (6-12 yrs of age) were
administered a variety of standardized tests including
the TONI, and the Beery VMI. Extensive data were
collected on potentially confounding variables
including sociodemographic variables, early
developmental milestones and child health status.
Blood Pb at time of testing
Blood Pb 8.1 (SD 3.5)
ug/dL
Blood Pb levels had no impact on TONI scores but this test
has limited evidence of validity in this population.
Significant negative associations were noted between
blood Pb levels and the Beery VMI suggesting an
association between impairment in visual-spatial skills in
Saudi children with blood Pb levels in the range of 2.3 to
27.4 ug/dL.
X
-------
Table AX6-2.4. Effects of Lead on Academic Achievement in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States
Lanphear et al. (2000)
U.S.
X
£
Needleman et al. (1990)
U.S.
Design: Cross-sectional. 4,853 U.S. children ages
six to 16 yrs enrolled in NHANES-III. Subjects
were administered the Arithmetic and Reading
subtests of the Wide Range Achievement Test-
Revised (WRATR). A number of medical and
sociodemographic covariates were assessed and
entered into multivariable models.
Blood Pb at time of testing
Geometric blood Pb 1.9
(SEO.l)ngML
2.1% with blood Pb
310 ug/dL
Design: Prospective cohort. Re-examination of the
Chelsea and Somerville cohort recruited in the
1970's (Needleman et al., 1979). 132 adolescents
were recalled. Large battery of tests was
administered to examine neurobehavioral deficits
and academic achievement in high school and shortly
following graduation. Extensive assessment of
medical and sociodemographic covariates.
Tooth (dentin) Pb
Tooth Pb median 8.2 ug/g
Following covariate adjustment, a statistically significant
relationship between blood Pb and WRATR performance
was found. A 0.70 point decrement in Arithmetic scores
and a 1 point decrement in Reading scores for each
1 ug/dL increase in blood Pb concentration was observed.
Statistically significant inverse relationships between blood
Pb levels and performance for both Reading and
Arithmetic subtests were found for children with blood Pb
concentrations <5 ug/dL. Authors concluded that results
of these analyses suggest that deficits in academic skills
are associated with blood Pb concentrations lower than
5 ug/dL. They cautioned, however, that two covariates
that have been shown to be important in other Pb studies
(i.e., parental IQ and HOME scores) were not available.
This may have over or under estimated deficits in
academic skills related to Pb. They further caution that, as
with all cross-sectional studies utilizing blood Pb as the
index of dose it is not clear whether deficits in academic
skills were due to Pb exposure that occurred sometime
during early childhood or due to concurrent exposure.
Nevertheless, concurrent blood Pb levels reflect both
ongoing exposure and preexisting body burden.
Subjects with dentin Pb levels >20 ppm were at higher risk
of dropping out of high school (adjusted OR = 5.8 [95%
CI: 1.4, 40.7]) and of having a reading disability (adjusted
OR = 5.8 [95% CI: 1.7, 19.7]). Higher dentin Pb levels
were also significantly associated with lower class
standing, increased absenteeism, and lower vocabulary and
grammatical reasoning scores on the Neurobehavioral
Evaluation System (NES). Authors conclude that undue
exposure to Pb has enduring and important effects on
objective parameters of success in life.
-------
Table AX6-2.4 (cont'd). Effects of Lead on Academic Achievement in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States (cont'd)
Bellinger et al. (1992)
U.S.
Design: Prospective longitudinal. 148 children in
the Boston Pb Study cohort were examined at 10 yrs
of age. The short-form of the Kaufman Test of
Educational Achievement (KTEA) was used to assess
academic achievement. Primary outcome was the
Battery Composite Score. Extensive assessment of
medical and sociodemographic covariates.
Cord and serial postnatal
blood Pb assessments.
Cord blood Pb grouping <3,
6-7, >10 ug/dL
Blood Pb at 2 yrs 6.5
(SD 4.9) ug/dL
After covariate-adjustment, blood Pb levels at 24 mos were
significantly predictive of lower academic achievement
(3 = 10.51, SE 0.20). Battery Composite Scores declined by
8.9 points for each 10 ug/dL increase in blood Pb. This
association was significant after adjustment for IQ. Authors
conclude that Pb-sensitive neuropsychological processing and
learning factors not reflected in measures of global intelligence
may contribute to deficits in academic achievement.
Levitonetal. (1993)
U.S.
X
Design: Prospective cohort. Teachers of-2000 eight
yr-old children born in 1 hospital in Boston between
1979 and 1980 filled out the Boston Teachers
Questionnaire (BTQ) to assess academic
performance and behavior. Limited information is
provided on the assessment of covariate factors but a
number were considered and controlled for in
multivariable analyses.
Cord blood Pb
Cord blood Pb 6.8 ug/dL
Tooth (dentin) Pb
Tooth Pb 2.8 ug/g
Following adjustment for potential confounding variables,
elevated dentin Pb concentrations were associated with
statistically significant reading and spelling difficulties as
assessed by the BTQ among girls in the sample. Authors
conclude that their findings support the case for Pb-associated
learning problems at levels that were prevalent at that time in
the general population. However, authors add that the inability
to assess child-rearing quality in this study conducted by mail
limits the inferences that can be drawn.
Australia
Fergusson et al. (1993,
1997); Fergusson and
Horwood(1993)
New Zealand
Design: Prospective cohort. Academic performance
was examined in a birth cohort of 1200 New Zealand
children enrolled in the Christchurch Health and
Development Study. Measures of academic
performance at 12-13 yrs included the Brut Reading
Test, Progressive Achievement Test, Test of
Scholastic Abilities, and teacher ratings of classroom
performance in the areas of reading, writing, and
mathematics. The growth of word recognition skills
from 8 to 12 yrs was also examined using growth
curve modeling methods. Academic achievement in
relationship to Pb was re-examined in this cohort at
18 yrs. Measures of academic achievement included
the Burt Reading Test, number of yrs of secondary
education, number of certificates passed (based on
national examinations), and leaving school without
formal qualifications (failing to graduate). Extensive
assessment of medical and social covariates.
Tooth (dentin) Pb
Tooth Pb 6.2 (SD 6.2) ug/g
Following covariate adjustment, dentin Pb levels were
significantly associated with virtually every formal index of
academic skills and teacher ratings of classroom performance
in 12-13 yr-olds. After adjustment for covariates, tooth Pb
levels greater than 8 ug/g were associated with significantly
slow growth in word recognition abilities with no evidence of
catch up. At 18 yrs, tooth Pb levels were significantly
associated with lower reading test scores, having a reading
level of less than 12 yrs, failing to complete three yrs of high
school, leaving school without qualifications, and mean
number of School Certificates passed. Authors conclude that
early exposure to Pb is independently associated with
detectable and enduring deficits in children's academic
abilities. They further conclude that their findings are
particularly significant in that they confirm the findings of
Needleman (1990), albeit in a cohort with lower levels of
exposure to environmental Pb.
-------
Table AX6-2.4 (cont'd). Effects of Lead on Academic Achievement in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia
Wang et al. (2002a)
Taiwan
Rabinowitz et al. (1992)
Taiwan
X
Oi
Oi
Design: Cross-sectional. 934 3rd graders living in
an urban industrial area of Taiwan. Outcome
variables were grades for Chinese (reading, writing),
mathematics, history, and natural science. Grades
were converted into individual class rankings to
avoid teacher bias. Limited data on medical and
sociodemographic covariates.
Design: Cross-sectional. Teachers of 493 children
in grades 1-3 filled out the Boston Teachers
Questionnaire (BTQ) to assess academic
performance and behavior. Sociodemographic and
medical covariate factors were assessed.
Blood Pb at time of
evaluation
Blood Pb 5.5 (SD 1.9)
Hg/dL
Tooth (dentin) Pb
ToothPb4.6(SD3.5)ug/g
Following covariate adjustment, blood Pb was significantly
associated with lower class ranking in all academic
subjects. Major shortcoming of this study is lack of
control for potentially important covariates such as
parental IQ. However, the relatively low levels of
exposure in this sample and strength and consistency of the
reported relationships suggest that Pb may be playing some
role in lowering academic performance.
Prior to adjustment for covariates, girls with higher
exposures to Pb evinced a borderline significant trend for
reading difficulties while byes displayed significantly
increased difficulties with respect to activity levels and
task attentiveness. In logistic regression models that
include significant covariate factors, the tooth Pb terms
failed to achieve statistical significance. Authors conclude
that Pb levels found in the teeth of children in this
Taiwanese sample are not associated with learning
problems as assessed by the BTQ.
Middle East
AlSalehetal. (2001)
Saudi Arabia
Class rank, as assessed by the teacher, was examined
in conjunction with blood Pb levels in 533 Riyadh,
Saudi Arabian girls (6-12 yrs of age). Extensive data
were collected on potentially confounding variables
including sociodemographic variables, early
developmental milestones and child health status.
Blood Pb at time of testing
BloodPb8.1(SD3.5)
ug/dL
A significant inverse relationship between blood Pb levels
and rank percentile scores was observed after adjusting for
a number of demographic and socioeconomic variables.
When multiple regression models were fitted to a subset of
students with blood Pb levels below 10 ug/dL, class rank
percentile continued to show a statistically significant
association with blood Pb levels.
-------
Table AX6-2.5. Effects of Lead on Specific Cognitive Abilities in Children — Attention/Executive Functions, Learning, and
Visual-spatial Skills
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States
Bellinger etal. (1994a)
U.S.
X
Stiles and Bellinger
(1993)
U.S.
Canfield et al. (2003b,
2004)
U.S.
Design: Prospective cohort. 79 subjects from the
original Chelsea and Somerville, MA Pb study were
re-evaluated at 19-20 yrs of age with the Mirsky
battery of attentional measures. Extensive measures
of medical and sociodemographic covariates.
Design: Prospective longitudinal. 148 subjects from
the Boston Pb Study were re-evaluated at 10 yrs of
age with an extensive neuropsychological battery.
Tests included the California Verbal Learning Test,
Wisconsin Card Sorting Test, Test of Visual-Motor
Integration, Rey-Osterieth Complex Figure, Story
Recall, Finger Tapping, and Grooved Pegboard.
Extensive measures of medical and
sociodemographic covariates.
Design: Prospective longitudinal. 170-174 children
from the Rochester Pb Study were administered a
number of learning and neuropsychological
functioning at 48, 54, and 66 mos of age. At 48 and
54 mos the Espy Shape School Task was
administered while at 66 mos the Working Memory
and Planning assessment protocols of the Cambridge
Neuropsychological Test Automated Battery
(CANTAB) was given. Extensive measures on
medical and sociodemographic covariates.
Tooth (dentin) Pb
Tooth Pb 13.7(SD11.2)
KXRF Bone Pb
Tibial bone Pb
(range 10) ug/g
Patellar bone Pb
(range15) ug/g
Cord and serial postnatal
blood Pb assessments
Cord blood Pb grouping <3,
6-7, >10 ug/dL
Blood Pb at 2 yrs 6. 5
(SD 4.9) ug/dL
Serial postnatal blood Pb
Blood Pb at 2 yrs 9.7 ug/dL
Lifetime avg blood Pb 7.2
(range 0-20) ug/dL
Higher tooth Pb concentrations were significantly
associated with poorer scores on the Focus-Execute and
Shift factors of the Mirsky battery. Few significant
associations were observed between bone Pb levels and
performance. Authors conclude that early Pb exposure
may be associated with poorer performance on
executive/regulatory functions, which are thought to
depend on the frontal or prefrontal regions of the brain.
Authors point out that the number of significant
associations was about equal to those that would be
expected by chance. However, tasks that assess attentional
behaviors and executive functions tended to among those
for which Pb was a significant predictor of performance.
Following covariate adjustment, higher blood Pb
concentrations at two yr were significantly associated with
lower scores on Freedom from Distractibility factor of the
Wechsler scales, increase in percentage of perseverative
errors on the Wisconsin Card Sorting Test and the
California Verbal Learning Test.
Following covariate adjustment, blood Pb level at 48 mos
was negatively associated with children's focused attention
while performing the Shape School Tasks, efficiency at
naming colors, and inhibition of automatic responding.
Children with higher blood Pb concentrations also
completed fewer phases of the Espy tasks and knew fewer
color and shape names. On the CANTAB battery, children
with higher lifetime avg blood Pb levels showed impaired
performance on spatial working memory, spatial memory
span, and cognitive flexibility and planning. Authors
conclude that the effects of pediatric Pb exposure are not
restricted to global measures of intellectual functioning and
executive processes may be at particular risk.
-------
Table AX6-2.5 (cont'd). Effects of Lead on Specific Cognitive Abilities in Children — Attention/Executive Functions,
Learning, and Visual-spatial Skills
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States (cont'd)
Ris et al. (2004)
U.S.
Design: Prospective longitudinal. 195 subjects from
the Cincinnati Pb Study were administered an
extensive and comprehensive neuropsychological
battery at 16-17 yrs of age. Domains assessed
included Executive Functions, Attention, Memory,
Achievement, Verbal Skills, Visuoconstructional,
and Fine Motor. Factor scores transformed to ranks
derived from a principal components factor analysis
of the neuropsychological test scores were the
primary outcome variables. Extensive measures on
medical and sociodemographic covariates.
Prenatal (maternal) and
serial postnatal blood Pb
assessments
Prenatal blood Pb 8.3
(SD 3.7) ug/dL
Blood Pb at 2 yrs 17.4
(SD 8.8) ug/dL
Following covariate adjustment, strongest associations
between Pb exposure and performance were observed for
factor scores derived from the Attention component, which
included high loadings on variables from the Conners
Continuous Performance Test. This relationship was
strongest in males. Authors speculate that since the
incidence of Attention Deficit/Hyperactivity Disorder is
greater in males in general, early exposure to Pb may
exacerbate a latent potential for such problems.
X
oo
-------
Table AX6-2.6. Effects of Lead on Disturbances in Behavior, Mood, and Social Conduct in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States
Sciarillo et al. (1992)
U.S.
X
Bellinger etal. (1994b)
U.S.
Demo (1990)
U.S.
Design: Cross-sectional. 150 2-5 yr-old children in
Baltimore separated into "high" (2 consecutive blood
Pb levels >15 ug/dL) and "low" groups. Mothers
filled out the Achenbach Child Behavior Checklist
(CBCL). The Center for Epidemiologic Studies
Depression Scale (CESD) was administered to
mothers as a control measure.
Design: Prospective cohort: 1782 children bom
within a 1-yr period at a single Boston hospital were
examined at 8 yrs of age. Teachers filled out the
Achenbach Child Behavior Profile (ACBP). Medical
and sociodemographic characteristics assessed by
questionnaire and chart review.
Design: Prospective cohort. Survey of 987
Philadelphia African-American youths enrolled in
the Collaborative Perinatal Project. Data available
from birth through 22 yrs of age. Analysis
considered 100 predictors of violent and chronic
delinquent behavior.
Screening blood Pbs at
various times before
assessment
High group 28.6
(SD 9.3) ng/dL
Low group 11.3
(SD 4.3) ng/dL
Umbilical cord blood Pb
Cord blood Pb 6.8
(SD3.1)ng/dL
Tooth (dentin) Pb
Tooth Pb 3.4
(SD2.4)ng/g
Blood Pb
Values not provided
When compared to lower exposed group, children in the
high group had a significantly higher CBCL Total
Behavior Problems Score (TBPS) and Internalizing and
Externalizing scores. After adjustment for maternal
depression, blood Pb concentrations were still significantly
associated with an increase in the TBPS. Children in high
group were nearly 3 times more likely to have a TBPS in
the clinical range. A significantly higher percentage of
children in the high group scored in the clinical range for
CBCL subscales measuring aggressive and destructive
behavioral tendencies.
Cord blood Pb levels were not associated with the
prevalence or nature of behavioral problems reported by
teachers. Tooth Pb levels were significantly associated
with ACBP Total Problem Behavior Scores (TPBS).
Statistically significant tooth Pb-associated increases in
both Externalizing and Internalizing scores were observed.
Each log unit increase in tooth Pb was associated with a
1.5-point increase in T scores for these scales. Authors
caution that residual confounding cannot be ruled out
because of the lack of information on parental
psychopathology or observations of the family
environment. However, these results are in accord with
other studies that social and emotional dysfunction may be
an important expression of elevated Pb levels during early
childhood.
Repeat offenders presented consistent features such as low
maternal education, prolonged male-provider
unemployment, frequent moves, and higher Pb
intoxication. In male subjects, a history of Pb poisoning
was among the most significant predictors of delinquency
and adult criminality.
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Table AX6-2.6 (cont'd). Effects of Lead on Disturbances in Behavior, Mood, and Social Conduct in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States (cont'd)
Needleman et al.
(1996)
U.S.
X
to
o
Dietrich et al. (2001)
U.S.
Needleman et al.
(2002)
U.S.
Design: Prospective cohort. 850 boys enrolled in the
Pittsburgh Youth Study were prescreened to assess
delinquent behavioral tendencies. Subjects who
scored in the 30th percentile on the risk score and an
equal number randomly selected from the remainder
form the sample of 530 subjects. Measures of
antisocial behavior were administered at 7 and 11 yrs
of age including the Self Reported Antisocial Behavior
scale (SRA), Self Report of Delinquent Behavior
(SRD), and parents' and teachers' versions of the
Achenbach Child Behavior Profile (CBCL). Extensive
assessment of medical and sociodemographic
covariates.
Design: Prospective longitudinal. 195 subjects from
the Cincinnati Pb Study were examined at 16-17 yrs of
age. Parents were administered a questionnaire
developed specifically for the study while CLS
subjects were given the Self Report of Delinquent
Behavior. Extensive assessment of medical and
sociodemographic covariates.
Design: Case-control. 194 adjudicated delinquents
and 146 non-delinquent controls recruited from high
schools in the City of Pittsburgh and Allegheny
County, PA. Covariate assessments were not
extensive but did include race, parental
sociodemographic factors, and neighborhood crime
rates.
Bone Pb by K-XRF
Bone Pb (exact
concentrations not reported)
Negative values treated
categorically as 1 and
positive values grouped into
quintiles.
Prenatal (maternal) and
serial postnatal blood Pb
assessments.
Prenatal blood Pb 8.3
(SD 3.7) ug/dL
Blood Pb at 2 yrs 17.4
(SD 8.8) ug/dL
Bone Pb by KXRF
Cases 11.0(SD 32.7) ug/g
Controls 1.5 (SD 32.1) ug/g
Following covariate-adjustment, parents of subjects with
higher Pb levels in bone reported significantly more
somatic complaints, more delinquent and aggressive
behavior, and higher Internalizing and Externalizing
scores. Teachers reported significant increase in scores on
somatic complaints, anxious/depressed, social problems,
attention problems, delinquent behavior, aggressive
behavior, internalizing and externalizing problems in the
higher bone Pb subjects. At 11 yrs, subject's SRD scores
were also significantly related to bone Pb levels. More
high Pb subjects had CBCL T scores in the clinical range
for attention, aggression, and delinquency. Authors
conclude that Pb exposure is associated with increased risk
for antisocial and delinquent behavior.
Prenatal (maternal) blood Pb was significantly associated
with a covariate-adjusted increase in the frequency of
parent-reported delinquent and antisocial acts. Prenatal
and measures of postnatal Pb exposure were significantly
associated with self-reported delinquent and antisocial
behaviors. Authors concluded that Pb might play a
measurable role in the development of behavioral problems
in inner-city children independent of other important social
and biomedical cofactors.
Cases had significantly higher avg concentrations of Pb in
tibia than controls. Following covariate adjustment,
adjudicated delinquents were 4 times more likely to have
bone Pb concentration >25 ug/g then controls. Bone Pb
level was the second strongest factor in the logistic
regression models, exceeded only by race. In models
stratified by race, bone Pb was exceeded as a risk factor
only by single parent status. Authors conclude that
elevated body Pb burdens are associated with increased
risk for adjudicated delinquency.
-------
Table AX6-2.6 (cont'd). Effects of Lead on Disturbances in Behavior, Mood, and Social Conduct in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Europe
Wasserman et al.
(1994)
Yugoslavia
X
to
Design: Prospective longitudinal. Birth cohort
of-300-400 infants followed since birth
residing in two towns in Kosovo, Yugoslavia,
one group near a longstanding Pb smelter and
battery manufacturing facility and another in a
relatively unexposed location 25 miles away.
379 children at 3 yrs of age were examined.
Parents were interviewed with the Achenbach
Child Behavior Checklist (CBCL). Extensive
assessment of medical and sociodemographic
covariates.
Maternal prenatal, umbilical cord
and serial postnatal blood Pb
Maternal blood Pb in exposed
area 19.9(SD 7.7) ug/dL,
unexposed area 5.6
(SD 2.0) ug/dL
Umbilical cord blood Pb in
exposed area 22.2
(SD 8.1) ug/dL,
unexposed area 5.5
(SD 3.3) ug/dL
Blood Pb at 2 yrs in exposed area
35.4 ug/dL, unexposed area
8.5 ug/dL
Following covariate adjustment, concurrent blood Pb levels
were associated with increased Destructive Behaviors on the
CBCL subscale, although the variance accounted for by Pb
was small compared to sociodemographic factors. As blood
Pb increased from 10 to 20 ug/dL, subscale scores increased
by 0.5 points. The authors conclude that while statistically
significant, the contribution of Pb to social behavioral
problems in this cohort was small compared to the effects of
correlated social factors.
Australia
Burns etal. (1999)
Australia
Fergusson et al. (1993)
New Zealand
Design: Prospective longitudinal. 322 subjects
residing in and near Port Pirie, Australia and
followed since birth were re-evaluated at 11-13
yrs of age. Parents completed the Achenbach
Child Behavior Checklist. Extensive
assessment of medical and sociodemographic
characteristics.
Design: Prospective cohort. 690-891 children
ages 12 and 13 yrs from the Christchurch Child
and Health Study, New Zealand were examined.
Mothers and teachers were asked to respond to
a series of items derived from the Rutter and
Conners parental and teacher questionnaires.
Extensive assessment of sociodemographic and
medical covariates.
Maternal prenatal, umbilical cord
and serial postnatal blood Pb
Antenatal avg blood
Pb 10.1 (SD 3.9) ug/dL
Umbilical cord blood Pb
9.4 (SD 3.9) ug/dL
Blood Pb at 2 yrs
geometric mean 21.3
(SD 1.2) ug/dL
Tooth (dentine) Pb
Tooth Pb range 3-12 ug/g
After adjustment for covariates, regression models revealed
that for an increase in avg lifetime blood Pb concentrations
from 10 to 30 ug/dL, the Externalizing behavior problem T
score increased by 3.5 points in boys (95% CI: 1.6, 5.4), but
only 1.8 points (95% CI: !0.1, 11.1) in girls. Internalizing
behavior problems were predicted to rise by 2.1 points (95%
CI: 0.0, 4.2) in girls by only 0.8 (95% CI: !0.9, 2.4) in boys.
Authors concluded that Pb exposure is associated with an
increase in externalizing (undercontrolled) behaviors in boys.
Statistically significant dose-effect relationships were
observed between tooth Pb levels and the
inattention/restlessness variable at each age. Authors
conclude that this evidence is consistent with the view that
mildly elevated Pb levels are associated with small but long
term deficits in attentional behaviors.
-------
Table AX6-2.6 (cont'd). Effects of Lead on Disturbances in Behavior, Mood, and Social Conduct in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Australia
Silvaetal. (1988)
New Zealand
X
to
to
As part of the 11-yr follow-up of the Dunedin
Multidisciplinary Health and Development Study, a
longitudinal study of a birth cohort of children bom
in Dunedin's only obstetric hospital, blood Pb levels
were measured in 579 children at age 11 yrs old.
The study sample was over-representative of higher
SES, but was found to be representative of Dunedin
children in educational attainment. Blood Pb levels
were examined in association with intelligence
assessed using the WISC-R and behavioral problems
as assessed by both parents and teachers.
Blood Pb at time of testing
Blood Pb at age 11 yrs 11.1
(SD 4.91, range 4-50) ug/dL
Log blood Pb levels were significantly correlated with most
measures of behavioral problems, including the Parents' and
Teachers' Rutter Behavioral Scale, the Parents' and
Teachers' Hyperactivity Scale, and the Teachers' Inattention
Scale, after adjustment for various potential confounders. No
associations were observed between log blood Pb levels and
IQ. Authors concluded that exposure to Pb is associated with
increases in children's' general behavioral problems,
especially in inattention and hyperactivity.
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Table AX6-2.7. Effects of Lead on Sensory Acuities in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States
Schwartz and Otto
(1991)
U.S.
Dietrich et al. (1992)
U.S.
X
to
Design: Cross-sectional. 3545 subjects 6-19 yrs old
who participated in the Hispanic Health and
Nutrition Examination Survey. Pure tone
audiometric evaluations were performed at 500 Hz,
2000 Hz, and 4000 Hz. Extensive measures on
medical and sociodemographic covariates.
Design: Prospective/longitudinal. 215 subjects
drawn from the Cincinnati Pb Study at the age of 5
yrs. Children were administered the SCAN-a
standardized test of central auditory processing.
Extensive measurement of medical and
sociodemographic covariates
Blood Pb at the time of
testing
Blood Pb 50th percentile
8 ug/dL
Prenatal (maternal) and serial
postnatal blood Pb
assessments
Prenatal blood Pb 8.3
(SD 3.7) ug/dL
BloodPbat2yrsl7.4(SD
8.8) ug/dL
Following covariate adjustment, higher blood Pb
concentrations were associated with an increased risk of
hearing thresholds that were elevated above the standard
reference level at all four frequencies. Blood Pb was also
associated higher hearing threshold when treated as a
continuous outcome. These relationships extended to blood
Pb levels below 10 ug/dL. An increase in blood Pb from 6 to
18 ug/dL was associated with a 2-dB loss at all frequencies.
Authors conclude that HHANES results those reported
earlier for NHANES-II.
Higher prenatal (maternal), neonatal and postnatal blood Pb
concentrations were associated with more incorrect
identification of common monosyllabic words presented
under conditions of muffling. Following covariate
adjustment, avg childhood blood Pb level remained
significantly associated with impaired performance on the
SCAN subtest. Authors conclude that Pb-related deficits in
hearing and auditory processing may be one plausible
mechanism by which an increased Pb burden might impede a
child's learning.
Europe
Osmanetal. (1999)
Poland
Design: Cross-sectional. 155 children 4-14 yr-old
living in an industrial region of Poland. Pure tone
audiometric evaluations were performed at 500 Hz,
1000 Hz, 2000 Hz, 4000 Hz, 6000Hz, and 8000 Hz.
Basic data on medical history, limited information on
sociodemographic covariates such as family
structure and income.
Blood Pb at the time
of testing
Blood Pb median 7.2
(range 1.9-28) ug/dL
Higher blood Pb concentrations were significantly associated
with increased hearing thresholds at all frequencies studied.
This relationship remained significant when analyses were
limited to subjects with blood Pb levels below 10 ug/dL.
Authors conclude that auditory function in children is
impaired at blood Pb concentrations below 10 ug/dL.
-------
Table AX6-2.8. Effects of Lead on Neuromotor Function in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States
Dietrich et al. (1993b);
Bhattacharya et al.
(1995);Risetal.
(2004)
U.S.
X
to
Design: Prospective longitudinal. Relationship
between Pb exposure and neuromotor function has
been examined in several studies on the Cincinnati Pb
Study Cohort from 6 to 17 yrs of age. At 6 yrs of age
245 subjects were administered the Bruininks-
Oseretsky Test of Motor Proficiency (BOTMP); at 6-
10 yrs of age subjects were assessed for postural
instability using a microprocessor-based strain gauge
platform system and at 16-17 yrs of age the fine-
motor skills of study subjects were assessed with the
grooved pegboard and finger tapping tasks (part of a
comprehensive neuropsychological battery).
Extensive measurement of medical and
sociodemographic factors.
Prenatal (maternal) and
serial postnatal blood Pb
assessments
Prenatal blood Pb 8.3
(SD 3.7) ug/dL
BloodPbat2yrsl7.4(SD
8.8) ug/dL
Following covariate adjustment, postnatal Pb exposure was
significantly associated with poorer scores on BOTMP
measures of bilateral coordination, visual-motor control,
upper-limb speed and dexterity and the Fine Motor
Composite score. Low-level neonatal blood Pb
concentrations were also significantly associated with poorer
scores on the aforementioned subtests, as well as measures
of visual-motor control. Postnatal Pb exposure was
significantly associated with greater postural instability in 6-
10 yr-old subjects and poorer fine-motor coordination when
examined at 16-17 yrs.
Authors conclude that effects of early Pb exposure extend
into a number of dimensions of neuromotor development.
Europe
Wasserman et al.
(2000a)
Yugoslavia
Design: Prospective longitudinal. Birth cohort of
—300-400 infants followed since birth residing in two
towns in Kosovo, Yugoslavia, one group near a
longstanding Pb smelter and battery manufacturing
facility and another in a relatively unexposed location
25 miles away. 283 children at age 54 mos were
administered the Beery Developmental Test of
Visual-Motor Integration (VMI) and the Bruininks-
Oseretsky Test of Motor Proficiency (BOTMP).
Extensive measurement of medical and
sociodemographic factors.
Maternal prenatal, umbilical
cord and serial postnatal
blood Pb
Maternal blood Pb in
exposed area 19.9
(SD 7.7) ug/dL,
unexposed area 5.6
(SD 2.0) ug/dL
Umbilical cord blood Pb in
exposed area 22.2
(SD 8.1) ug/dL,
unexposed area 5.5
(SD 3.3) ug/dL
Blood Pb at 2 yrs in exposed
area 35.4 ug/dL, unexposed
area 8.5 ug/dL
Following covariate-adjustment, the log avg of serial blood
Pb assessments to 54 mos was associated with lower Fine
Motor Composite and VMI scores. Pb exposure was
unrelated to gross motor performance. With covariate
adjustment, an increase in avg blood Pb from 10 to 20 ug/dL
was associated with a loss of 0.62 and 0.42 points
respectively, in Fine Motor Composite and VMI. Authors
noted that other factors such as indicators of greater
stimulation in the home make a larger contribution to motor
development than Pb.
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Table AX6-2.9. Effects of Lead on Direct Measures of Brain Anatomical Development and Activity in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States
Trope etal. (1998)
U.S.
Trope etal. (2001)
U.S.
X
to
Cecil et al. (2005)
U.S.
Design: Case-control. One 10 yr-old subject with
history of Pb poisoning and unexposed 9 yr-old
cousin. Magnetic Resonance Imaging (MRI) and
Magnetic Resonance Spectroscopy (MRS) were
used to assess differences in cortical structures and
evidence of neuronal loss. This was the first study
to attempt to determine in vivo structural and/or
metabolic differences in the brain of a child
exposed to Pb compared with a healthy control.
Design: Case-control. 16 subjects with a history of
elevated blood Pb levels before 5 yrs of age and
5 age-matched siblings or cousins were evaluated.
Avg age at time of evaluation was 8 yrs. Magnetic
Resonance Imaging (MRI) and Magnetic
Resonance Spectroscopy (MRS) were used to
assess differences in cortical structures and
evidence of neuronal loss.
Design: Prospective/longitudinal. 48 young adults
ages 20 to 23 yrs were re-examined. Functional
MRI (fMRI) was used to examine the influence of
childhood Pb exposure on language function.
Subjects performed a verb generation/finger-
tapping paradigm. Extensive measurement of
medical and sociodemographic covariates
Blood Pb
Pb poisoned case 51 ug/dL
at 38 mo
Unexposed control not
reported.
Blood Pb
Range in Pb-exposed 23 to
65 ug/dL
Controls <10 ug/dL
Blood Pb
Avg childhood blood Pb
13.9 (SD 6.6, range
4.8-31.1) ug/dL
Both children presented with normal volumetric MRI. MRS
revealed a significant alteration in brain metabolites, with a
reduction in N-acetylaspartate:creatine ratio for both gray
and white matter compared to the subject's cousin. Authors
conclude that results suggest neuronal loss related to earlier
Pb exposure.
All children had normal MRI examinations, but Pb-exposed
subjects exhibited a significant reduction in
N-acetylaspartate:creatine and pohosphocreatine ratios in
frontal gray matter compared to controls. Authors conclude
that Pb has an effect on brain metabolites in cortical gray
matter suggestive of neuronal loss.
Higher avg childhood blood Pb levels was significantly
associated with reduced activation in Broca's area in the left
hemisphere and increased activation in the right temporal
lobe, the homologue of Wemicke'a area in the left
hemisphere. Authors conclude that elevated childhood Pb
exposure strongly influences neural substrates of semantic
language function on normal language areas with
concomitant recruitment of contra-lateral regions resulting in
a striking dose-dependent atypical organization of language
function.
-------
Table AX6-2.9 (cont'd). Effects of Lead on Direct Measures of Brain Anatomical Development and Activity in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Latin America
Rothenberg et al. (2000)
Mexico
Design: Prospective/longitudinal. 1135-7yr-old
children from the Mexico City Prospective Study
were re-examined. Brain stem auditory evoked
potentials were recorded to assess the impact of
prenatal and postnatal Pb exposure on development
of auditory pathways. Results adjusted for gender
and head circumference.
Blood Pb
Prenatal (20 wks) 8.1
(SD4.1)ng/dL
Cord 8.7 (SD 4.3) ug/dL
Postnatal 18 mo 10.8
(SD 5.2) ug/dL
Prenatal blood Pb at 20 wks was associated with decreased
interpeak intervals. After fitting a nonlinear model to these
data, I-V and III-V interpeak intervals decreased as blood Pb
rose from 1 to 8 ug/dL and increased as blood Pb rose from
8 to 30 ug/dL. Increased blood Pb at 12 and 48 mos was
related to decreased conduction intervals for I-V and II-V
across the entire blood Pb range suggesting pathway length
effects.
X
Oi
to
Oi
Asia
Meng et al. (2005)
China
Design: Case-control. 6 subjects with blood Pb
concentrations 327 ug/dL and 6 controls with
blood Pb concentrations <10 ug/dL were evaluated
with Magnetic Resonance Imaging (MRI) and
Magnetic Resonance Spectroscopy to evaluate
structural abnormalities and differences in N-
acetylaspartate, creatine, and choline in frontal
lobes and hippocampus of cases and controls.
Blood Pb
Cases 37.7 (SD 5.7) ug/dL
Controls 5.4 (SD 1.5)
ug/dL
All children presented with normal MRI. Peak values of N-
acetylaspartate, choline, and creatine in all four brain regions
were reduced in Pb exposed children relative to controls.
Authors conclude that reduced brain N-acetylaspartate in
cases may be related to decreased neuronal density or loss.
Reduced choline signal may indicate decreased cell
membrane turnover or myelin alterations while lower
creatine may indicate reduced neuronal cell viability.
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Table AX6-2.10. Reversibility of Lead-related Deficits in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States
Ruff etal. (1993)
U.S.
Roganetal. (2001);
Dietrich et al. (2004)
U.S.
X
to
Design: Intervention study, non-randomized.
126 children with complete data age 13 to 87 mos
and with blood Pb levels between 25 and 55 ug/dL
were given chelation with ETDA and/or therapeutic
iron where indicated. At baseline and follow-up,
patients were evaluated with the Bayley Scales of
Infant Development, Mental Development Index,
or Stanford Binet Scales of Intelligence depending
upon age.
Design: Double blind, placebo-controlled
randomized clinical trial. The Treatment of Pb-
Exposed Children (TLC) clinical trial of 780
children in 4 centers was designed to determine if
children with moderately elevated blood Pb
concentrations given succimer would have better
neuropsychological outcomes than children given
placebo. Children between 12 and 33 mos of age
were evaluated 3 yrs following treatments and
again at 7 and 7.5 yrs of age. A wide range of
neurological, neuropsychological, and behavioral
tests was administered. Assessment of potentially
confounding factors included sociodemographics
and parental IQ.
Blood Pb at time of
treatment
BloodPb31.2(SD6.5)
ug/dL
Blood Pb
Baseline blood Pb 26
(SD 26.5) ug/dL in both
drug and placebo groups
Without respect to treatment regimen, changes in
performance on cognitive measures after 6 mos were
significantly related to changes in blood Pb levels after
control for confounding factors. Standardized scores on tests
increased 1 point for every 3 ug/dL decrement in blood Pb.
Succimer was effective in lowering blood Pb levels in
subjects on active drug during the first 6 mos of the trial.
However, after 1 yr differences in the blood Pb levels of
succimer and placebo groups had virtually disappears.
3 yrs following treatment, no statistically significant
differences between active drug and placebo groups were
observed for IQ or other more focused neuropsychological
and behavioral measures. When evaluated at 7 and 7.5 yrs of
age, TLC could demonstrate no benefits of earlier treatment
on an extensive battery of cognitive, neurological, behavioral
and neuromotor endpoints. Authors conclude that the TLC
regimen of chelation therapy is not associated with
neurodevelopmental benefits in children with blood Pb levels
between 20 and 44 ug/dL and that these results emphasize
the importance of taking environmental measures to prevent
exposure to Pb in light of the apparent irreversibility of Pb-
associated neurodevelopmental deficits.
-------
Table AX6-2.10 (cont'd). Reversibility of Lead-related Deficits in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States (cont'd)
Liu et al. (2002)
U.S.
Design: Prospective longitudinal clinical trial.
Data from the Treatment of Pb-Exposed Children
(TLC) used to examine prospective relationships
between falling blood Pb levels and changes in
cognitive functioning. 741 children recruited
between 13 and 33 mos of age were assessed at
baseline and 6 mos later with the Bayley Mental
Development Index (MDI) and 36 mos post-
randomization with the Wechsler Preschool and
Primary Scales of Intelligence-Revised to
obtain IQ.
Blood Pb
Baseline blood Pb 26.2
(SD 5.1) ug/dL
36 mos post-randomization
blood Pb 12.2 (SD 5.2)
ug/dL
TLC found no overall effect of changing blood Pb level on
change in cognitive test scores from baseline to 6 mos.
Slope estimated to be 0.0 points per 10 ug/dL change in
blood Pb. From baseline to 36 mos and 6 mos to 36 mos,
falling blood Pb levels were significantly associated with
increased cognitive test scores, but only because of an
association in the placebo group. Authors conclude that
because improvements were not observed in all children, the
data do not provide support that Pb-induced cognitive
impairments are reversible. Although the possible
neurotoxicity of succimer cannot be ruled out.
X
to
oo
Latin America
Kordasetal. (2005);
Rico et al. (2006)
Mexico
Design: Double-blind, placebo-controlled
nutritional supplementation clinical trial conducted
among 602 1st grade children ages 6-8 yrs in
Torreon, Mexico. Subjects received iron, zinc,
both or placebo for 6 mos. Parents and teachers
filled out the Conners Rating Scales at baseline and
follow-up six mos following the end of
supplementation to index behavioral changes
following therapy. In addition, 11 cognitive tests
of memory, attention, visual-spatial abilities, and
learning were administered, including WISCR-M at
baseline and follow-up 6 mos later.
Blood Pb
Baseline blood Pb 11.5
(SD 6.1) ug/dL
No significant effects of treatment on behavior or cognition
could be detected with any consistency. Authors conclude
that this regimen of supplementation does not result in
improvements in ratings of behavior or cognitive
performance.
Australia
Tongetal. (1998)
Australia
Design: Prospective longitudinal. 375 children
from the Port Pirie Prospective Study were
followed from birth to the age of 11-13 yrs. Bayley
Mental Development Index (MDI) at 2 yrs, the
McCarthy Scales General Cognitive Index (GCI)
and IQs from the Wechsler Intelligence Scale
served as the primary indicators of intellectual
status. The purpose of the study was to assess the
reversibility of Pb effects on cognition in
relationship to declines in blood Pb over time.
Postnatal blood Pb
Mean blood Pb at 2 yrs
21.2 ug/dL declining to
7.9 ug/dL at 11-13 yrs
Although blood Pb levels declined substantially, covariate
adjusted scores on standardized measures of intellectual
attainment administered at 2, 4, 7, and 11-13 yrs of age were
unrelated to declining body burden. Authors conclude that
effects of early exposure to Pb during childhood are not
reversed by a subsequent decline in blood Pb concentration.
-------
ANNEX TABLES AX6-3
AX6-29
-------
Table AX6-3.1. Neurobehavioral Effects Associated with Environmental Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States
Krieg et al. (2005)
1988-1994
U.S.
Muldoon et al. (1996)
U.S.
X
oo
O
4,937 adults aged 20-59 yrs from
NHANES III completed three
neurobehavioral tests. Regression analyses
of neurobehaqvioral test and log of blood
Pb concentration adjusted for sex, age
education, family income, race/ethnicity,
computer or video game familiarity,
alcohol use, test language, and survey
phase.
325 women from rural location (mean age
71) and 205 women from a city location
(mean age 69) participants in the Study for
Osteoporotic Fractures had the association
of nonoccupational Pb exposure and
cognitive function examined. Logistic
regression determined effect of blood Pb
on neuropsychological performance.
Mean blood Pb 3.3 ug/dL
RangeO.7to41.7ug/dL
Rural group
Blood Pb 5 ug/dL
Urban group
Blood Pb 5 ug/dL
No statistically significant relationship between blood Pb concentration
and mean simple reaction time, symbol-digit substitution latency and
errors and serial digit learning trials to criterion and total score after
adjustments for covariates.
Groups were significantly different with the urban group more educated
and smoked and drank more. Performance in each group stratified by
exposure into three groups (low <4 ug/dL, medium 4-7 ug/dL, high
>7 ug/dL rural and >8 ug/dL) — no significant associations were
present in the urban group but the rural group had significantly poorer
performance with increasing blood Pb for Trails B (OR = 2.6 [95% CI:
1.04, 6.49]), Digit Symbol (OR = 3.73 [95% CI: 1.57, 8.84]),and
Reaction Time in the lower (OR = 2.84 [95% CI: 1.19, 6.74]) and
upper extremities (OR = 2.43 [95% CI: 1.01,5.83]). Thefactthat
marked differences exist between the low Pb groups for rural and urban
(the lowest 15th percentile) suggests the differences between the two
groups are unrelated to Pb. Response time for reaction time across Pb
groups increased for the rural group and decreased or remained the
same for the urban group. As response time is sensitive to Pb effect,
this raises question whether factors not measured accounted for
difference. Namely MMSE for the whole population was 25 (15-26)
with poorer performance in the rural group. The clinical cutoff score
for MMSE is 24 suggesting the presence of clinical cognitive disorders.
Even though this is a simple neuropsychological battery up to 9 were
unable to perform some of the tests including 3 on the MMSE.
-------
Table AX6-3.1 (cont'd). Neurobehavioral Effects Associated with Environmental Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States (cont'd)
Paytonetal. (1998)
U.S.
Rhodes etal. (2003)
U.S.
X
Wright et al. (2003)
U.S.
141 healthy men in VA normal aging study
evaluated every 3 to 5 yrs with cognitive
battery and blood Pb and once a
measurement of patella and tibia bone Pb.
Statistics are confusing as it is not clear
when ANCOVA is used and how the
groups are created.
526 participants with mean age 67 yrs,
47% had education level of high school or
less. Mood symptoms evaluated with Brief
Symptom Inventory (BSI). Use of logistic
regression adjusting for covariates
examined association of BSI scales and
blood Pb and bone Pb levels.
736 healthy men (mean age 68) in
Normative Aging Study examined every 3
to 5 yrs were administered the Mini-
Mental State Exam (MMSE). Linear
regression examined relationship of
MMSE and blood Pb, patella and tibia
bone Pb measurements after adjusting for
covariates.
Mean blood Pb 6 ug/dL
Mean patella bone Pb 32
ug/g
Mean tibia bone Pb 23 ug/g
bone mineral
Mean blood Pb 6 ug/dL
Mean tibia Pb 22 ug/g
Mean patella Pb 32 ug/g
Mean blood Pb 5 ug/dL,
Mean patella bone Pb 30
Mean tibia bone Pb 22 ug/g
Regressions adjusted for age and education found significant
relationship of blood Pb with Pattern Comparison (perceptual speed),
Vocabulary, Word List Memory, Constructional Praxis, Boston
Naming Test, and Verbal Fluency Test. Only for Constructional Praxis
were bone Pb and blood Pb significantly associated. Mechanism most
sensitive to low levels Pb exposure believed to be response speed.
Vocabulary is significantly associated with blood Pb. Education is
negatively correlated to bone and blood Pb. It is not clear how multiple
comparisons were handled
BSI found mood symptoms for anxiety and depression were potentially
associated with bone Pb levels. Education was inversely related to
bone Pb and high school graduates had significantly higher odds of
Global Severity Index and Positive Symptom Total.
Mean MMSE score 27. Relation of MMSE scores <24 (n = 41) and
blood Pb by logistic regression found OR = 1.21 (95% CI: 1.07,1.36)
and for patella Pb OR = 1.21 (95% CI: 1.00, 1.03) and tibia Pb OR =
1.02 (95% CI: 1.00, 1.04). Risk of MMSE <24 when comparing the
lowest and highest quartiles of patella Pb was 2.1 (95%CI: 1.1,4.1),
for tibia Pb was 2.2 (95% CI: 1.1, 3.8) and blood Pb was 3.4 (95% CI:
1.6, 7.2). Interaction between patella Pb and age, and blood Pb and age
in predicting MMSE found steeper decrease in MMSE score relative to
age in the higher quartiles of patella Pb and blood Pb.
MMSE very sensitive to yrs of education below 8 yrs. In this study 213
subjects had less than high school education. If the community
dwelling population had older individuals with less education living in
areas with higher past pollution the confounding may be impossible to
sort out. Initially at beginning of NAS subjects were eliminated with
chronic medical problems or blood pressure >140/90. It is not
addressed how the development of medical conditions during the
duration of the study are handled.
-------
Table AX6-3.1 (cont'd). Neurobehavioral Effects Associated with Environmental Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
X
oo
to
United States (cont'd)
Weisskopf et al.
(2004b)
U.S.
466 men, mean age 70 yrs, in the VA
Normative Aging Study had 2 MMSE tests
3.5 yrs apart.
Mean blood Pb 4 ug/dL
Mean patella bone Pb 23
Mean tibia bone Pb 1 9 ug/g
Baseline mean MMSE score was 27 and mean change in MMSE
score over 3.5 yrs was 0.3. Change in MMSE associated with one
interquartile range increment for bone Pb and blood Pb found
relationship between patella Pb and change in MMSE was unstable
when patella Pb is 390 ug/g bone mineral. Examination of patella Pb
below this level found a greater inverse association with MMSE at
lower Pb concentrations (3 = !0.25 [95% CI: 10.45, 10.05]). A similar
but weaker association existed for tibia Pb when values 367 ug/g
bone mineral were removed (3 = !0.19 [95% CI: 10.39,0.02]). There
was no association of MMSE change and blood Pb (3 = 10.01 [95%
CI: 10.13,0.11]). There was no interaction of age and bone Pb.
These are very high bone Pb levels for environmental exposure. The
biological plausibility of change in the MMSE over 3.5 yrs would
have been reinforced if the change by functional domain in the
MMSE was provided.
Europe
Nordberg et al. (2000)
Sweden
762 participants, mean age 88 yrs, in a study
of aging and dementia examined MMSE.
Used blood Pb as dependent and examined
contribution of covariates and MMSE.
Mean blood Pb 3.7 ug/dL
Mean MMSE 25 found no relation of blood Pb and MMSE. In this
population was fairly homogenous, all elderly Swedes, and the
likelihood of prior exposure to elevated Pb levels was low.
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Table AX6-3.2. Symptoms Associated with Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Canada
Lindgrenetal. (1999)
Canada
Holnessetal. (1988)
Canada
X
Smelter workers (n = 467) with a mean age
of 40 yrs completed the Profile of Mood
Scale. Factor structure of POMS validated in
this occupational population. Regression
analysis determined association with Pb
exposure.
47 demolition workers with acute Pb
intoxication - Phase 1 - were followed with
blood Pb and symptoms during engineering
modifications to control exposure -
Phases 2-4. Workers stratified by blood Pb
and symptom frequency was analyzed.
Mean (SD, range) blood Pb
28 (8.5, 4-62) ug/dL
Mean (SD, range) IBL 711
(415.5, 1-1537) ng-yr/dL
Phase I - Mean blood Pb
59 ug/dL
Phase 2 - Mean blood Pb
30 ng/dL
Phase 3 - Mean blood Pb
19 ng/dL
Phase 4 - Mean blood Pb
17 ug/dL
Factor analysis found one factor labeled "general distress" composed
of POMS subscales anger, confusion, depression, fatigue and tension
and a second factor labeled 'psychological adjustment.' IBL was
significantly associated with 'general distress' after adjustment for the
covariates (3 = 0.28 [SE 1.51 H 10!4], p = 0.01) while there was no
relation with blood Pb. The factor structure of POMS originally
validated in a clinical population had six mood subscales however the
factor structure in this occupational population was found to have
only two subscales.
Below blood Pb <50 ug/dL, workers reported symptoms of fatigue
(25%), headache (14%), dizzy (9%), sleep (8%), abdominal cramps
(8%), muscle ache (8%), paresthesiae (8%), appetite (7%),
constipation (6%), and weakness (6%). All symptoms were
significantly lower except for paresthesiae when compared to group
with blood Pb >70 ug/dL. Of interest, at beginning of Phase 4 when
mean blood Pb was 13 ug/dL, no symptoms were reported. At the
end of Phase 4, mean blood Pb was 17 ug/dL and one worker
complained of fatigue.
Europe
Lucchini et al. (2000)
Italy
66 workers in Pb manufacturing, mean age
40 (8.7) yrs and 86 controls mean age 43
(8.8) yrs were administered a questionnaire
with neuropsychological (14 items), sensory-
motor (3 items), memory (4 items) and
extrapyramidal (8 items), 10 Parkinson
symptoms and the Mood Scale. Group
comparisons and linear regression examined
relationship of symptoms and Pb exposure.
Pb workers
Mean (SD, range) blood Pb
27(11.0, 6-61) ug/dL
Mean (SD, range) TWA 32
(14.1,6-61) ug/dL
Mean (SD, range) IBL 410
(360.8, 8-1315) ug-yr/dL
Controls
Mean (SD, range) blood Pb
8 (4.5, 2-21) ug/dL
Pb exposed worker reported confusion, somnolence, abnormal
fatigue, irritability, and muscular pain more frequently (p < 0.04).
There were no group differences for the parkinsonism symptoms or
Mood Scale. Linear regression combing exposed and control group
found neurological symptoms significantly associated with blood Pb
r = 0.22, p = 0.006). Neuropsychological symptoms were
significantly higher in the High-IBL compared to the Low-IBL group.
The estimated threshold for a significant increase (prevalence of 5%)
of a high score for neurological symptoms was at a blood Pb of
12 ug/dL.
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Table AX6-3.2 (cont'd). Symptoms Associated with Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Latin America
Maizlish et al. (1995)
Venezuela
X
43 workers from a Pb smelter, mean age 34
(9) yrs and 47 nonexposed workers, mean
age35(ll) yrs completed the profile of
mood states (POMS) questionnaire and a
questionnaire of symptoms of the central and
peripheral nervous system, and
gastrointestinal. Prevalence ratios used to
examine symptoms and Pb. ANCOVA and
linear regression adjusting for potential
confounders examined relationship of Pb
exposure and POMS.
Pb workers
Mean (SD) blood Pb 43
(12.1) ug/dL
Mean (SD) peak blood Pb
60 (20.3) ug/dL
Mean (SD) TWA 48 (12.1)
ug/dL
Controls
Mean (SD) blood Pb 15 (6)
ug/dL
Mean (SD) peak blood Pb
15(6)ng/dL
Mean (SD) TWA 15 (SD 6)
ug/dL
Significantly increased relative risks found for difficulty
concentrating (RR = 1.8 [95% CI: 1.0, 3.1]), often being angry or
upset without reason (RR = 2.2 [95% CI: 1.2, 4.1]), feeling
abnormally tired (RR = 2.2 [95% CI: 0.9, 5.3]) and joint pain
(RR = 1.8 [95% CI: 1.0, 3.3]). The six subscales of the POMS were
not significantly different between the exposed and control groups.
However dose-related analysis found significantly poorer scores for
tension-anxiety and blood Pb (p = 0.009), hostility and blood Pb
(p = 0.01) and TWA (p = 0.04), and depression and blood Pb
(p = 0.003) and peak Pb (p = 0.003) and TWA (p = 0.004).
Asia
Schwartz et al.
(200 la)
Korea
Lee et al. (2000)
Korea
803 Pb-exposed Korean workers, mean age
40 yrs completed the Center for
Epidemiologic Studies Depression Scale.
Linear regression examined for association
of CES-D and Pb biomarkers after adjusting
for the covariates.
95 Korean Pb exposed workers, mean age 43
yrs, completed questionnaire of Pb-related
symptoms present over last three mos.
Relationship between symptom score and
measures of Pb exposure assessed by linear
regression. Logistic regression use to model
presence or absence of symptoms for
gastrointestinal, neuromuscular, and general.
Mean (SD) blood Pb 32
(15.0) ug/dL
Mean (SD) tibia Pb 37
(40.3) ug/g bone mineral
DMSA-chelatable Pb Mean
(SD) 289 (167.7) ug
Mean (SD)ZPP 108 (60.6)
ug/dL
Mean(SD)ALAU3(2.8)
mg/L
Mean(SD) blood Pb 45
(SD 9.3) ug/dL
After adjustment for age, gender and education significant
associations found for CES-D and tibia Pb (3 = 0.0021 [SE 0.0008];
p < 0.01) but not with blood Pb. This occupational Pb-exposed
populations had higher past Pb exposure compared to the current
mean blood Pb of 32 ug/dL.
Workers with DMSA-chelatable Pb above the median of 261 ug were
6.2 (95% CI: 2.4, 17.8) times more likely to have tingling or
numbness in their extremities, 3.3 (95% CI: 1.2, 10.5) times more
likely to experience muscle pain and 3.2 (95% CI: 1.3, 7.9) times
more likely to feel irritable. The workers with higher chelatable Pb
were 7.8 (95% CI: 2.8, 24.5) times more likely to experience
neuromuscular symptoms compared to workers with lower chelatable
Pb. In this study ZPP predicted weakness of ankle and wrist
(OR = 2.9 [95% CI: 1.1, 8.1]) and fatigue (OR = 2.9 [95% CI:
1.1, 8.7]) while ALAU predicted inability to sleep(OR= 5.4 [95%
CI: 1.2, 33.2]) and blood Pb was not significantly associated with any
symptoms. A measure of Pb in bioavailable storage pools was the
strongest predictor of symptoms particularly neuromuscular.
-------
Table AX6-3.2 (cont'd). Symptoms Associated with Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Niu et al. (2000)
China
44 Pb-exposed workers (17 men, 27 women)
from Pb printing houses, mean age 35 (4.9)
and education 9.3 (no SD) yrs and 34
controls (19 men and 15 women), mean age
33 (7.4) yrs and education 9.5 (no SD) yrs
completed the profile of mood state as part of
theNCTB. ANCOVA controlling for age,
sex and education examined group
differences and linear regression for dose-
response relationship.
Mean blood Pb 29
(SD26.5)|ig/dL
(8 workers blood Pb
exceeded 50 ng/dL)
Controls
Mean blood Pb 13
(SD 9.9) ng/dL
(1 control blood Pb
exceeded 50 |ig/dL)
POMS subscales for confusion (F = 3.02, p < 0.01), fatigue (F = 3.61,
p < 0.01), and tension (F = 2.82, p < 0.01) were significantly elevated
in the Pb exposed group. Regression analyses found a dose response
(data not shown).
X
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Table AX6-3.3. Neurobehavioral Effects Associated with Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States
Fiedler et al. (2003)
New Jersey
40 workers with Pb exposure, mean age
48 (9.5) yrs completed a neurobehavioral
battery and was compared to 45 Pb/solvent
workers, mean age 47 (10.2), 39 solvent
exposed workers, mean age 43 (9.4), and
33 controls, mean age 44 (10.2). Group
differences and dose-effect relationships
were assessed after adjusting for potential
confounding.
Mean (SD) blood Pb
Hg/dL; mean (SD) bone Pb
ppm (dry weight)
Pb workers
14 (11.7); 2.7 (0.7)
Pb/Solvent workers
12 (11.6); 2.8 (0.6)
Solvent workers
5(4.1); !1.8(1.8)
Controls
4(1.4); !1.1(1.6)
Of nineteen outcomes, significant differences found on the California
verbal learning test (CVLT) (p = 0.05) and positive symptom distress
index on the Symptom checklist-90-R. On the CVLT the controls
performed significantly better on trials 2 and 3 demonstrating
efficiency of verbal learning. Symbol digit substitution (SDS)
approached significance (p = 0.09) with Pb and Pb/solvent group
slower on latency of response but not accuracy. Bone Pb was a
significant predictor of latency of response on SDS, total errors on
paced auditory serial addition task and simple reaction time non-
preferred hand. Bone Pb and SRT, preferred hand approached
significance. This is a confusing study design as bone Pb is used as a
predictor in workers both with and without occupational Pb exposure.
X
Oi
oo
Oi
Canada
Lindgren et al. (1996)
Canada
467 Canadian former and current, French
and English speaking Pb smelter workers,
mean age 43(11.0) yrs and education
10 (3.2) yrs were administered a
neuropsychological battery in English or
French. Data analyses used MANCOVA
adjusting for age, education, measure of
depressive symptoms and self reported
alcohol use.
Mean (SD) yrs employment
18(7.4)
Mean (SD) blood Pb 28
(8.4) ng/dL
Mean (SD) TWA 40
(4-66) ng/dL
Mean (SD) IBL 765
(1-1626) ng-yr/dL
Fourteen neuropsychological variables examined by MANCOVA
with the grouping variable exposure (high, medium and low) and the
covariates, age, education, CES-D, and alcohol use found no exposure
term significant until yrs of employment, a suppressor term, was
added as a covariate. IBL exposure groups differed significantly (df
2,417) on digit symbol (F = 3.03, p = 0.05), logical memory (F = 3.29,
P = 0.04), Purdue dominant hand (F = 4.89, p = 0.01), and trails A
(F = 3.89, p = 0.02) and B (F = 3.2, p = 0.04). This study showed a
dose-effect relationship between cumulative Pb exposure (IBL) and
neuropsychological performance at a time when there was no
association with current blood Pb.
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Table AX6-3.3 (cont'd). Neurobehavioral Effects Associated with Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Canada (cont'd)
Bleecker et al. (2002)
Canada
X
Bleecker et al. (2005a)
Canada
256 smelter workers from the above
population were currently employed and
took the test battery in English. Their mean
age was 41 (7.9) yrs, and education 10 (2.8)
yrs. The goal was to determine if
educational achievement as measured by
WRAT-R Reading modified performance on
MMSE. Linear regression assessed the
contribution of age, WRAT-R, education,
alcohol intake, cigarette use, IBL and
IBLHWRAT-R on MMSE performance.
256 smelter workers currently employed and
took the test battery in English. Their mean
age was 41 (7.9) yrs, and education 10 (2.8)
yrs. The purpose was to determine whether
components of verbal memory as measured
on the Rey Auditory Verbal Learning Test
(RAVLT) were differentially affected by Pb
exposure. Linear regression and ANCOVA
assessed the relationship of Pb and
components of verbal learning and memory.
Mean (SD) blood Pb 28
(8.8) ng/dL
Mean (SD) IBL 725 (434)
Hg-yr/dL
Mean (SD) blood Pb 28
(8.8) ng/dL
Mean (SD) TWA 39 (12.3)
Mean (SD) IBL 725 (434)
Hg-yr/dL
MMSE had a median (range) score of 29 (19-30). The most common
errors were recall of 3 items (38%), spell world backwards (31%),
repetition of "no ifs ands or buts" (21%) and copy a design to two
intersecting pentagons (16%). WRAT-R reading used as an additional
measure of educational achievement because it was a stronger predictor
of MMSE performance than yrs of education. The significant
interaction (AR2 = 2%, p = 0.01) explained by a dose-effect between
IBL and MMSE only in the 78 workers with a WRAT-R reading grade
level less than 6. The workers with higher reading grade levels and the
same cumulative Pb exposure were able to compensate for the effects
of Pb on the MMSE because of increased cognitive reserve.
Outcome variables RAVLT a word list test included measures of
immediate memory span and attention (Trial 1), best learning (Trial V),
incremental learning across the five trials (Total Score), and storage
(Recognition) and retrieval (Delayed Recall) of verbal material. TWA
significantly contributed to the explanation of variance for Trial V
(AR2 = 1.4%, p < 0.03) and Delayed Recall (*R2 = 1.4%, p = 0.03)
after adjusting for age and WRAT-R while IBL did the same with
Recognition (*R2 = 2.0%, p = O.02) and Delayed Recall
(*R2 = 1.1%, p = 0.06). Workers stratified into 3 group by increasing
clinical memory difficulties-Group 1 had normal encoding, storage and
retrieval; Group2 could encode and store verbal information but had
difficulty with retrieval and Group 3 had abnormal encoding, storage
and retrieval but was still able to learn new verbal information.
ANCOVA adjusting for age and WRAT-R compared Pb exposure
across the memory groups. Blood Pb showed no difference but TWA
and IBL were significantly higher in Group 3 compared to Group 1
(p < 0.05 for both). Internal strategies used on the RAVLT over the
five trials found that Groups 1 and 2 remembered more words from the
beginning of the list while group 3 remembered more from the end.
At a time when blood Pb was not associated with performance,
cumulative Pb exposure resulted in poorer storage and retrieval of
previously learned material. Alterations in the ability to organize
materials in long term memory interferes with retrieval efficiency.
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Table AX6-3.3 (cont'd). Neurobehavioral Effects Associated with Occupational Lead Exposure in Adults
Reference, Study
Location, and Period Study Description Pb Measurement Findings, Interpretation
Canada (cont'd)
Bleecker et al. (1997a)
New Brunswick
1992-1993
X
oo
oo
Bleecker et al. (1997b)
New Brunswick
1992-1993
The performance of the 467 current and retired
smelter workers as described in Lindgren et al.
(1996) administered a screening
neuropsychological battery by testers blinded
to the degree of Pb exposure of the worker had
their performance compared to age matched
norms. If performance on two or more tests in
any functional domain was below 1.5 standard
deviations the worker was invited for a
complete clinical evaluation. Eighty current
workers were identified by this criterion.
Mean yrs - age 44 (8.4) yrs, education 8 (2.8)
yrs and duration employed 20 (5.3) yrs. Five
neuropsychological tests commonly associated
with Pb exposure were examined for a
differential association with blood Pb,
IBL,TWA and bone Pb.
Of the 80 current smelter workers described
above 78 completed a simple visual reaction
time (SRT) and had mean yrs age 44 (8.2) yrs,
education 8 (7.2) yrs and duration employed
20 (5.6) yrs.
Mean (SD) blood Pb 26
(7.07) ug/dL
Mean (SD) TWA 42
(8.4) ug/dL
Mean (SD) IBL 903
(305.9) ug-yr/dL,
Mean (SD) tibial bone Pb
41 ug/g bone mineral
Mean (SD) blood Pb, 26
(7.2) ug/dL
Mean (SD) blood Pb from
bone 7 (4.2) ug/dL
Mean (SD) blood Pb from
environment 19
(7.0) ug/dL
Mean (SD) bone Pb 40
(25.2) ug/g bone mineral
Relationship of 5 neuropsychological tests with 4 measures of Pb dose
after adjusting for age age2 and education, education2 found RAVLT trial
V and Verbal Paired Associates were associated with blood Pb
(AR2 = 6.2%, p = 0.02; *R2 = 5.5%, p = 0.07) and TWA (*R2 = 3.2%,
p = 0.09; *R2 = 13.9%; P = 0.00) while Digit Symbol and Grooved
Pegboard were associated with TWA (*R2 = 6.1%, p = 0.00; *R2 = 5.5%,
p = 0.02) and IBL (*R2 = 4.8%, p = 0.01; *R2 = 5.7%, p = 0.02). Only
grooved pegboard was associated with bone Pb (*R = 4.2%, p = 0.05).
Block design was not associated with any measures of Pb dose. Age was
an effect modifier with grooved pegboard. There was enhanced slowing in
older workers when compared to younger workers with the identical IBL.
SRT consisted of 44 responses to a visual stimulus at interstimulus
intervals (ISI) varying between 1 through 10 seconds with a mean SRT
(median) of 262 (179 to 387) ms. Blood Pb and median SRT had a
curvilinear relationship R2 = Pb+ Pb2, 13.7%, p < 0.01) after adjusting for
age and education with slowing of SRT beginning at a blood Pb of
—30 ug/dL. No relationship existed between bone Pb and SRT. There was
a stronger association between Pb and Pb2 and SRT for the longer ISIs of 6
to 10 seconds (R = 13.9%, p < 0.01), as age was significantly related to
the shorter ISI = s but not the longer ones. In this population the
contribution of bone Pb to blood Pb had been previously where estimated
where for a bone Pb level of 100 ug Pb/g bone mineral, 17 ug Pb/dL of the
blood Pb was derived from internal bone stores with the remainder from
the environment. Blood Pb was fractionated to that from bone (blood Pb-
bn) vs. blood Pb from the environment (blood Pb-en). Regression analysis
to examine the relationship of blood Pb-bn and blood Pb-en and SRT after
adjusting for the covariates found significant contribution to the variance
of SRT only for blood Pb-en (R2 for blood Pb-en + blood Pb-en2 = 14.4%,
p < 0.01). The absence of a contribution by age and more stable responses
with ISIs of 6 to 10 sec supports using this component of SRT.
-------
Table AX6-3.3 (cont'd). Neurobehavioral Effects Associated with Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Canada (cont'd)
Lindgren et al. (2003)
New Brunswick
1992-1993
X
oo
vo
Braun and Daigneault
(1991)
Quebec
In an attempt to separate the effects of past
high Pb exposure from a lower proximate
exposure, examination of the pattern of Pb
levels of the 467 Canadian Pb smelter
workers found 40 workers who had high past
exposure followed by yrs where 90% of
blood Pb were above 40 ug/dL (High-
High = H-H) while another group of 40
workers had similar past high Pb exposure
followed by yrs where 90% of blood Pb were
below 40 ug/dL (High-Low = H-L). The
groups did not differ on age, education, yrs
of employment or CES-D. Five outcomes
examined-Purdue Pegboard assembly,
Block Design, Digit Symbol, Rey Auditory
Verbal Learning Test-total score, delayed
Logical Memory.
41 workers from a secondary Pb smelter,
mean age 35 (9.6) yrs and yrs of education
10 (2.1) were compared to a control group
mean age 37 (lO.l)yrs and yrs of education
11 (1.3) on tests of cognitive and motor
function. MANCOVA and dose-effect
relationships after adjusting for potential
confounders were performed.
Mean (SD) IBL for past
exposure
H-H 633 (202.2) ug-yr/dL
H-L 557 (144.8) ug-yr/dL
Mean (SD) IBL for the
proximate exposure
H-H 647 (58.7) ug-yr/dL
H-L 409 (46.4) ug-yr/dL
Mean (SD) blood Pb
H-H 37 (5.1) ug/dL
H-L 24 (5.2) ug/dL
Mean (SD) TWA 53
(7.5) ug/dL
Mean (SD) maximum
blood Pb 87 (22.4) ug/dL
Of the five neuropsychological measures examined only RAVLT
(total score) and Logical Memory (delayed) were significantly
different after adjusting for the covariates in the two pattern groups.
Use of regression analyses found pattern group contributed
significantly (R2 = 4%, p < 0.05) to the explanation of variance in
RAVLT after accounting for current blood Pb (R2 = 3%, p < 0.10) and
IBL measures (R2 = 7%, p < 0.01). For past IBL, H-H pattern
correlated more strongly with RAVLT (r = !0.21) while H-L pattern
had no relationship with past exposure (r = 0.08). For proximate IBL
the difference was maintained between H-H (r = !0.11) and H-L
pattern (r = 0.00). The authors suggested that the absence of an
association between past high Pb exposure and verbal memory in the
H-L pattern group may reflect reversibility of function when blood Pb
is maintained below 40 ug/dL.
None of the measures of cognitive executive function showed group
differences. Partial correlation adjusting for age and education with
dose related variables found no statistical significance. On motor
function the exposed workers had significantly slower simple reaction
time (p = 0.05). However partial correlations with measures of dose
found dose-effect correlation in both negative and positive directions.
Group of exposed workers was mixed for Pb exposure with 11
currently working and the remainder with no exposure up to 84 mos.
Also two of the exposed workers had been treated with chelation.
-------
Table AX6-3.3 (cont'd). Neurobehavioral Effects Associated with Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Europe
Hsnninen et al. (1998)
Finland
X
Lucchini et al. (2000)
Italy
Fifty-four Pb battery workers were
stratified by those whose blood Pb never
exceeded 50 ug/dL (n = 26) (group 1)
and those who had higher exposure in the
past (n = 28) (group 2) to examine the
neuropsychological effects of current low
level blood Pb from higher blood Pb in
the past. Mean age group Iwas 42 (9.3)
yrs, education 8(1.7) yrs and yrs of
exposure 12 (6.7). Mean age group 2 was
47 (6.2) yrs, education 8 (1.0) yrs and yrs
of exposure 21 (6.9). Analysis included
partial correlations within the groups and
ANCOVA within group 1 divided at the
median TWA3 of 29 ug/dL.
66 workers in Pb manufacturing, mean
age 40 (8.6) yrs, mean education 8 ( 2.4)
yrs and mean exposure time 11 (9) yrs
and a control group of 86 with mean age
43 (8.8) yrs, mean yrs of education 9
(2.7) yrs. Group differences examined
and dose-effect relationship with
correlation and ANOVA.
Group 1
MeanlBL 330 ug-yr/dL
Maximum blood Pb 40 ug/dL
TWA 29 ug/dL
Tibial Pb 20 ug/g
Calcaneal Pb 79 ug/g
Group 2
Mean IBL 823 ug-yr/dL
Maximum blood Pb 69 ug/dL
TWA 40 ug/dL
Tibial Pb 35 ug/g
Calcaneal Pb 100 ug/g
IBL, TWA and maximum
blood Pb were also calculated
for the previous 3 yrs with a
median TWA3 of 29 ug/dL
Pb workers
Mean (SD) blood Pb 28
(11) ug/dL
Mean (SD) IBL 410
(360.8) ug-yr/dL
Mean (SD) TWA 32
(14.1) ug/dL
Mean (SD) yrs exposed
11(8.1)
Control
Mean (SD) blood Pb 8
4.5) ug/dL
Partial correlations controlling for age, sex and education in group 1
found block design, digit symbol, digit span, similarities, Santa Ana 1
and memory for design significantly associated with recent measures
of exposure and embedded figures with maximum blood Pb. In group
2 embedded figures, digit symbol, block design, and associative
learning were associated with IBL and /or maximum blood Pb.
Calcaneal Pb was weakly associated with digit symbol, digit symbol
retention, and synonyms. There was no association with tibial Pb in
either group. Group 1 divided at the median TWA3 of 29 ug/dL
found the high group had lower scores for visuospatial and
visuoperceptive tasks (digit symbol, embedded figures and memory
for design). Overall past high exposure, blood Pb >50 ug/dL, had the
greatest effect on tests requiring the encoding of complex visually
presented stimuli. The authors conclude that the effect of Pb on brain
function is better reflected by history of blood Pb than content of Pb
in bone.
No association with neuropsychological tests (addition, digit span,
finger tapping symbol digit and motor test from Luria) and blood Pb,
TWA or IBL were found. Blood Pb and visual contrast sensitivities at
the high frequencies were significantly associated for the entire group.
Blood Pb and serum prolactin in the whole group was significantly
associated. Increased prolactin secretion occurs with a variety of
neurotoxins and reflects impaired dopamine function in the pituitary.
The estimated threshold for a significant increase of high prolactin
levels was at a blood Pb of 10 ug/dL.
-------
Table AX6-3.3 (cont'd). Neurobehavioral Effects Associated with Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
_sterberg et al. (1997)
Sweden
38 workers, median age 42 (no range) yrs at
a secondary smelter stratified by finger bone
Pb concentration and along with 19 controls
matched triplets for age, education and job
level. Median yrs employed 10 (2-35).
X
High bone Pb
Median (range) bone 32
(17-101) ug/g
Median (range) blood Pb
38 (19-50) ng/dL
Median (range) peak blood
Pb 63 (46-90) ng/dL
Median (range) IBL 408
(129-1659) ng-yr/dL
Low bone Pb
Median (range) bone 16
(!7to49)ng/g
Median (range) blood Pb
34 (17-55) ng/dL
Median (range) peak blood
Pb 57 (34-78) ng/dL
Median (range) IBL 250
(47-835) ng-yr/dL
Controls
Median (range) bone 4
(!19tol8)ng/g
Median (range) blood Pb 4
(1-7) ng/dL
A cognitive test battery (36 tests) covering learning and memory,
visuomotor function, visuospatial function, concentration and
sustained attention found no impairment or dose-response
relationships with any of the markers of Pb exposure. Deviating test
scores (belong to 10% lowest reference norms) were less in high
bone Pb (1 vs. 4 vs. 4). None of the deviating parameters were
significantly correlated with any of the Pb indices. Even when age
was taken into account the significant associations between outcome
and Pb exposure metrics did not exceed chance in light of the
numerous analyses performed. These were the most heavily Pb-
exposed workers in Sweden. It was unusual that the 2 visuomotor
tasks significantly different had better performance in the Pb-
exposed workers compared to the controls.
-------
Table AX6-3.3 (cont'd). Neurobehavioral Effects Associated with Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Stolleiyetal. (1991)
England
X
to
Stollery (1996)
England
Earth et al. (2002)
Austria
Seventy Pb-exposed workers, mean age
41 (no SD) yrs, grouped by blood Pb
(<20 |ig/dL, 21-40 ng/dL and 41-80 ng/dL)
examined on three occasions each separated
by four mos. Tested on a computer for
syntactic reasoning, delayed five choice
reaction time, visual spatial memory, and
category search task.
Same as above except this was a further
analysis of the five choice reaction time.
47 Pb storage-battery workers, mean age
40 (9.7) yrs and 53 nonexposed controls,
mean age 39 (8.4) yrs were matched for age
and verbal intelligence. Group differences
and dose-response relationship were
explored.
Low blood Pb
Mean blood Pb 14 ng/dL
MeanZPP13mg/dL
Mean urinary ALA 2 mg/L
Mean yrs exposed 7
Medium blood Pb
Mean blood Pb 31 ng/dL
MeanZPP33mg/dL
Mean urinary ALA 3 mg/L
Mean yrs exposed 10
High blood Pb
Mean blood Pb 52 ng/dL
MeanZPP77mg/dL
Mean urinary ALA 6 mg/L
Mean yrs exposed 11
Same as above
Pb workers
Mean (SD) blood Pb 31
(11.2)ug/dL
Mean (SD) IBL 384
(349.0) ng-yr/dL
Mean (SD) yrs employed
12(9.0)
Controls
Mean (SD) blood Pb 4
(2.0) ng/dL
Pb exposure was stable over the 8 mos of testing. The low Pb group
drank significantly less alcohol and rated their work as less
demanding. Performance and exposure stable except in the high Pb
group where decision time was slowed more than movement time
along with concentration difficulties that remained stable across
testing sessions. Movement and decision times were significantly
correlated for each duration of waiting. On the memory test of
recalled nouns, the memory deficit associated with Pb (r = 10.35,
p = 0.003) was restricted to recall of nouns unrelated to task
(distracters) (p = 0.04) that did not improve with repetition suggestive
of difficulties with incidental learning. Workers with blood Pb
>40 ng/dL had impairments that correlated best with avg blood Pb
over the preceding 8 mos. Workers with blood Pb between 21 to
40 ng/dL had essentially no impairment.
Movement and decision slowing was correlated with blood Pb.
Slowed movement time was constant across response-stimulus
intervals in contrast to decision time that was increasingly affected by
Pb especially at the shortest response-stimulus intervals.
This supported the finding that decision gaps, central in origin, as
opposed to movement gaps are selectively affected by Pb exposure in
this population.
Significant differences were found for block design (p # 0.01), visual
recognition (p #0.01) and Wisconsin card sorting (categories
p = 0.0005, total errors p = 0.0025, perseverations p = 0.001, loss of
sorting principle p = 0.003) but not SRT or digit symbol. In the
exposed group partial correlation adjusting for age found no
significant associations with IBL (n = 53). In the entire group the full
correlation was significant for blood Pb and Wisconsin card sorting,
block design and visual recognition (n = 100). Visuospatial abilities
and executive function were better predicted by blood Pb than
cumulative Pb exposure. It is unusual that a frontal lobe task is
associated with blood Pb when SRT and digit symbol sensitive to the
affects of Pb are not.
-------
Table AX6-3.3 (cont'd). Neurobehavioral Effects Associated with Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Winker etal. (2005)
Austria
Winker et al. (2006)
Austria
X
48 workers formerly Pb-exposed, mean
duration since last exposure 5 (3.5) yrs, and
mean age 40 (8.8) yrs were matched with 48
controls for age, verbal intelligence, yrs of
education and number of alcoholic drinks.
Group differences and dose-response
relationship were explored.
The same 48 workers formerly Pb-exposed
described above were compared to the
47 exposed workers described by Barth et al.
(2002). Both groups were comparable for
age and verbal intelligence. Group
differences and differences by duration of
exposure and exposure absence were
evaluated.
Formerly Pb-exposed
Mean (SD, range) blood Pb
5.4(2.7,1.6-14.5) ng/dL
Mean (SD)IBL 4153.3
(36930.3) ng-yr/dL
Controls
Mean (SD, range) blood Pb
4.7(2.5,1.6-12.6) ng/dL
Exposed workers
Mean (SD, range) blood Pb
31(11.2, 10.6-62.1) ng/dL
Mean(SD)IBL4613
(4187.6)ng-yr/dL
Formerly Pb-exposed
Mean (SD, range) blood Pb
5.4(2.7,1.6-14.5) ng/dL
Mean (SD)IBL 4153.3
(36930.3) ng-yr/dL
No significant differences on neurobehavioral battery were present
when groups compared by t-tests for paired samples. When the
groups were combined, partial correlation adjusting for age found
significant negative correlation between blood Pb and Block Design,
(r = -0.28, p < 0.01) Visual Recognition (r = -0.21, p < 0.05) and
Digit Symbol Substitution (r = -0.26, p < 0.01). The authors
conclude that the cognitive deficits associated with low-level Pb
exposure are reversible. However there appears to be a residual effect
primarily from those with the highest past Pb exposure.
Mann-Whitney test found significantly better performance in the
formerly Pb-exposed workers for Block Design (p = 0.005) and
Wisconsin Card Sorting Test (categories p = 0.0005, total errors
p = 0.005, perseverations p = 0.0095 and loss of sorting principle
p = 0.02). To further examine the reduction of cognitive impairment
with absence of exposure, workers were stratified by duration of
exposure and exposure absence - short exposure and long absence;
long exposure and long absence; short exposure and short/no absence
and long exposure and short/no absence. Linear contrasts for Block
Design (p = 0.003) and Wisconsin Card Sorting Test (categories-
p < 0.001, total errors p = 0.001, perseverations p = 0.019 and loss of
sorting principle p = 0.030) were highly significant in the
hypothesized direction. Results were believed to support reversibility
of cognitive deficits related to occupational Pb exposure.
-------
Table AX6-3.3 (cont'd). Neurobehavioral Effects Associated with Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Latin America
Maizlishetal. (1995)
Venezuela
X
43 workers from a Pb smelter, mean age 34
(9) yrs and 47 nonexposed workers, mean
age 35 (11) yrs completed the WHO
neurobehavioral core test battery. ANCOVA
and linear regression adjusting for potential
confounders examined relationship of Pb
exposure and NCTB.
Pb workers
Mean (SD) blood Pb 43
(12.1)ng/dL
Mean (SD) peak blood Pb
60 (20.3) ug/dL
Mean (SD) TWA 48
(12.1)ng/dL
Controls
Mean (SD) blood Pb 15
(6) ug/dL
Mean (SD) peak blood Pb
15 (6) ug/dL
Mean TWA 15 (6) ug/dL
Group comparison was significant for SRT (p = 0.06) but the Pb
exposed workers performed faster. Linear regression found SRT
poorer performance with blood Pb and TWA but not significant.
With peak blood Pb SRT improved with increasing Pb exposure.
In this study only symptoms were significantly different between
the groups.
Asia
Schwartz et al.
(200 la)
South Korea
803 Korean Pb-exposed workers, 80% men
and 20% women, mean age 40 (10.1) yrs
from a variety of industries, and 135
controls, 92% men and 8% women, mean
age 35 (9.1) yrs. Educational levels Pb-
exposed workers/controls
#6 yrs = 23% / 7%, 7-9 yrs 23% / 11%, 10-
12 yrs = 46% / 70%, and >12 yrs 8% / 12%.
Group differences on neurobehavioral testing
after controlling for covariates and linear
regression controlling for covariates
examined the presence of a dose-effect
relationship.
Pb workers
Mean (SD) blood Pb 32
(15) ug/dL
Mean (SD) tibia bone Pb
37 (40.3) ng/g
Mean (SD) DMSA-
chelatablePb level 186
(208.1)ug
Controls
Mean (SD) blood Pb 5
(1.8)ng/dL
Mean (SD) Tibia bone Pb 6
(7) ug/g
Nineteen outcomes examined. Compared to controls Pb exposed
workers performed significantly worse on SRT, Digit Span, Benton
Visual Retention, Colored Progressive Matrices, Digit Symbol, and
Purdue Pegboard after controlling for age, gender and education. The
association of DMSA with test performance was lost by the addition
of blood Pb. Bone Pb was not associated with neurobehavioral
performance. Blood Pb was the best predictor for significant
decrements in neurobehavioral performance on trails B (3 = 10.0025
[SE 0.0009], p < 0.01), Purdue Pegboard (dominant 3 = 10.0159 [SE
0.0042], p < 0.01; non-dominant 3 = 0.0169 [SE 0.0042], p < 0.01;
both 3 = 10.0142 [SE 0.0038], p < 0.01; assembly 3 = 10.0493 [SE
0.0151], p < 0.01), and Pursuit Aiming (# correct 3 = 10.1629 [SE
0.0473], p < 0.01; # incorrect 3 = 10.0046 [SE 0.0023], p < 0.05). The
magnitude of the effect for these eight tests significantly associated
with blood Pb was an increase in blood Pb of 5 ug/dL was equivalent
to an increase of 1.05 yrs in age. Use of Lowess lines for Purdue
Pegboard (assembly) and Trails B suggested a threshold at blood Pb
18 ug/dL after which there is a decline of performance.
-------
Table AX6-3.3 (cont'd). Neurobehavioral Effects Associated with Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Schwartz et al. (2005)
South Korea
1997-2001
X
Longitudinal decline in neurobehavioral
performance examined in 576 of the above
group of Pb exposed workers who completed
3 visits at one yr intervals.
Mean age at baseline was 41 (9.5) yrs and
job duration 9 (6.3) yrs and 76% were men.
Compared to non-completers Pb workers
who completed 3 visits were 3.3 yrs older,
baseline mean blood Pb was 2.0ug/dL lower,
on the job 1.6 yrs longer, 24% women vs.
10% of noncompleters, and usually had less
than high school education. Models
examined short-term vs. long-term effects.
Final model had current blood Pb, tibia bone
Pb and longitudinal blood Pb and covariates.
Baseline mean (SD) blood
Pb31(14.2)ug/dL
Mean (SD) tibia
Pb 38 (43) ug/g
Blood Pb from baseline correlated with those from visit 2 and 3 and
baseline tibial Pb correlated with that measured at visit 2. Cross-
sectional associations of blood Pb or short-term change occurred with
Trails A (3 = 10.0020 [95% CI: 10.0040, 10.0001]) and B
(3 = 10.0037 [95% CI: 10.0057, 10.0017]), Digit Symbol (3 = 10.0697
[95% CI: 10.1375, 10.0019]), Purdue Pegboard
(dominant 3= 10.0131 [95% CI: 10.0231, 10.0031]; non-dominant
3 = 10.0161 (95% CI: 10.0267, 10.0055); both (3 = 10.0163, [95% CI:
10.0259, 10.0067]; assembly (3 = 10.0536 [95% CI: 10.0897,
10.0175]), and Pursuit Aiming (# corrects = 0.1526, [95% CI:
10.2631, 10.0421]) after covariates. However, longitudinal blood Pb
was only associated with poorer performance on Purdue Pegboard
(non-dominant 3 = 10.0086 [95% CI: 10.0157, 10.0015]; both
(3 = 10.0063 [95% CI: 10.0122, 0.0004]; assembly (3 = 10.0289 [95%
CI: 10.0532, 10.0046]). Historical tibial bone Pb was associated with
digit symbol (3 = 10.0067 [95% CI: 10.0120, 0.0014]) and Purdue
Pegboard (dominant 3 = 10.0012, [95% CI: 10.0024, 10.0001]).
Magnitude of Pb associations was expressed as the number of yrs of
increased age at baseline that was equivalent to an increase of Pb from
the 25th to 75th percentile. At baseline, these Pb associations were
equivalent to 3.8 yrs of age for cross-sectional blood Pb, 0.9 yrs of
age for historical tibial Pb and 4.8 yrs of age for longitudinal blood
Pb. Analyses showed decline in performance over time related to
tibia Pb.
-------
Table AX6-3.3 (cont'd). Neurobehavioral Effects Associated with Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Hwang et al. (2002)
South Korea
X
Oi
-k
Oi
From the above cohort of 803 Korean Pb
workers, 212 consecutively enrolled workers,
were examined for protein kinase C (PKC)
activity and the relations between blood Pb
and neurobehavioral performance. PKC
activity assessed by measuring levels of
phosphorylation of three erythrocyte
membrane proteins. Seventy-four percent of
workers were men, mean age 36(0.8)yrs,
duration of exposure 9 (0.6) and education
93% had high school or less. For the female
workers, mean age 47 (0.9) yrs, duration of
exposure 6 (0.5), and education 95% had
high school or less.
Male workers
Mean (SD) blood Pb 32
(13.0)ng/dL
Mean(SD)tibiaPb38
(39.6) iig/g
Mean (SD) ZPP 69
(47.8)
Female workers
Mean (SD) blood Pb 20
(9.2) ng/dL
Mean (SD) tibia Pb 26
(14.7) ng/g
Mean (SD) ZPP 72
(29.7) ng/dL
Blood Pb was associated significantly with decrements in Trails B
(3 = !0.003 [SE 0.002], p < 0.10), SRT (3 = 10.0005 [SE 0.0003],
p < 0.10) and Purdue Pegboard (dominant 3 = 10.21 [SE 0.010],
p < 0.05); non-dominant (3 = 10.021 [SE 0.010], p < 0.05); both
(3 = 10.021 [SE 0.009], p < 0.05). PKC activity as measured by back-
phosphorylation of erythrocyte membrane proteins was not associated
with neurobehavioral test scores. Addition of the interaction term of
blood Pb by back-phosphorylation dichotomized at the median found
significant effect modification with the association of higher blood Pb
and poorer neurobehavioral performance occurring only among
workers with lower back-phosphorylation levels that corresponds to
higher in vivo PKC activity. Association of blood Pb and SRT for the
52 kDa subunit with high in vivo PKC activity (adjusted 3 = !0.001,
p < 0.01) and for low in vivo PKC (adjusted 3 = 10.0001, p = 0.92).
The authors suggest that PKC activity may identify a subpopulation at
increase risk of neurobehavioral effects of Pb.
Chuangetal. (2005)
Taiwan
27 workers from a glazing factory were
administered a computerized
neurobehavioral battery 3 times over 4 yrs.
At yr 1, the mean age was 40 (9.6) yrs. In
the first yr workers were compared to a
referent group matched for age and
education. Neurobehavioral performance
compared in first yr to referent group with
adjustment for age and Vocabulary.
Generalized mixed linear mixed models
analyzed relationship between blood Pb level
and neurobehavioral test performance after
adjusting for age and Vocabulary.
Pb workers
Yrl
Mean (SD) blood Pb 26
(12)
Yr3
Mean (SD) blood Pb 11
(6.4)
Yr4
Mean (SD) blood Pb 8 (6.9)
Referent
Mean (SD) blood Pb 7 (4.2)
Referents scored significantly lower on questionnaire for chronic
symptoms in yr 1. In the mixed model analyses finger tapping
dominant (p = 0.008) and non-dominant (p = 0.025) were
significantly inversely associated with blood Pb. Pattern comparison
(p < 0.001) and Pattern memory (p = 0.06) improved significantly as
blood Pb levels improved. Chronic symptoms and neurobehavioral
performance appear to reverse when Pb exposure is decreased.
However since the referent group was not tested in yr 3 and yr 4 it
was not possible to control for practice effect known to occur with
repeat neurobehavioral testing even at two yr intervals.
-------
Table AX6-3.3 (cont'd). Neurobehavioral Effects Associated with Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Tsai et al. (2000)
Taiwan
Chia et al. (2004)
Singapore
X
Chia etal. (1997)
Singapore
19 Pb workers and 19 referents included in
the above publication, mean age 39 yrs in
both groups and mean education 10 (2.9) and
9 (3.2) yrs, respectively, were tested with a
computerized neurobehavioral battery.
Alcohol use was similar. Mean duration of
Pb exposure 6 (2.5) yrs. Student's t
compared neurobehavioral performance
between the two groups.
120 workers from Pb stabilizer factories,
mean age 40 (10.7) yrs, duration of exposure
10.2 (7.9) were given a neurobehavioral
battery. Genotyping of ALAD
polymorphisms was performed. ANCOVA
used to test for differences in
neurobehavioral performance among ALAD
polymorphism types adjusting for age,
exposure duration and blood Pb.
50 Pb battery manufacturing workers, mean
age 36 (10.6) yrs, education 8.6 (2.1) yrs
duration of employment 9 (7.4) yrs and
97 controls, mean age 34 (3.7) yrs, and
education 12(1.8) yrs were administered a
neurobehavioral battery. ANCOVA and
linear regression used to assess relationship
of Pb dose and performance.
Mean (SD) blood Pb 32
(12.2) ug/dL
Referent
Mean (SD) blood Pb 7
(2.7) ug/dL
Mean (SD) blood Pb 22
(9.4) ug/dL
Mean(SD)ALAD0.6
(0.25) urn of
porphobilinogen/h/ml of
RBC
Mean(SD)ALAU0.9
(0.56) mg/g creatinine
Pb workers
Median (range) blood Pb of
38 (13.2-64.6) ug/dL
Median (range) IBL 264
(10.0-1146.2) ug-yr/dL
Controls
Median (range) blood Pb 6
(2.4-12.4) ug/dL
Poorer performance in Pb workers for finger tapping, dominant and
non-dominant, and continuous performance task but only finger
tapping was significant. Pb workers performed better than referents
on Associate Learning, Pattern Comparison Test, Pattern Memory
Test, Visual Delay and Associate Learning Delayed that was
attributed to higher mean education.
Frequency of ALAD11, 87%, ALAD12, 12%, andALAD22, 1%.
Mean blood Pb adjusting for age and exposure duration was 20 ug/dL
for ALAD11 (n= 107)and20.4 ug/dL for ALAD12 and22 (n= 13).
However ALAU was significantly higher in ALAD11 (p = 0.023).
After adjusting for the covariates significant differences for grooved
pegboard dominant hand (p = 0.01), non-dominant hand (p = 0.04),
and grooved pegboard mean time (p = 0.006) were found between
ALAD11 and ALAD12 and 22. Considering cognitive tests were part
of battery it is surprising education was ignored. As noted by the
authors the study only had 13 in the group with better performance
and the ALAD 12 or 22 genotypes limiting the power.
Significant group differences for Santa Ana, grooved pegboard, digit
symbol, pursuit aiming and Trails A and B after adjusting for age,
education, smoking, ethnic group and alcohol use. When the exposed
group was stratified by age, in the group >35 yrs the poorer
performance on digit symbol and Trails A was significantly
associated with cumulative Pb and not blood Pb after adjusting
for age and education.
-------
Table AX6-3.3 (cont'd). Neurobehavioral Effects Associated with Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Niu et al. (2000)
China
X
oo
Boey and Jeyaratnam
(1988)
Singapore
44 Pb-exposed workers (17 men, 27 women)
from Pb printing houses, mean age 35 (4.9)
and education 9.3 (no SD) yrs and 34
controls (19 men and 15 women), mean age
33 (7.4) yrs and education 9.5 (no SD) yrs
completed the NCTB. ANCOVA controlling
for age, sex and education examined group
differences and linear regression for dose-
response relationship.
49 Pb-exposed workers, mean age 26 (7.6)
yrs and 36 controls, mean age 30 (6.4) yrs
completed SRT and 8 psychological tests
covering attention, vigilance, visual-motor
speed, short-term memory, visuomotor
tracking, visual scanning, and manual
dexterity. Control group was matched for
education level. Discriminate analysis of
neurobehavioral tests performed to determine
which best discriminate the groups.
Pb workers
Mean (SD) blood Pb 29
(26.5) ng/dL
(8 workers blood Pb
exceeded 50 |ig/dL)
Controls
Mean (SD) blood Pb 13
(9.9) ng/dL
(1 control blood Pb
exceeded 50 |ig/dL)
Pb workers
Mean (SD) blood Pb 49
(15) ng/dL
Controls
Mean (SD) blood Pb 15
(3)
SRT (F = 2.30, p < 0.05), digit symbol (F = 4.81, p < 0.01) pursuit
aiming # correct (F = 7.186, p < 0.01) and pursuit aiming total
(F = 6.576, p < 0.01) had significantly poorer performance compared
to controls. No repression analyses provided.
Six tests were significantly different between the two groups-Digit
Symbol, Bourdon-Wiersma, Trails A, Santa Ana dominant, Flicker
Fusion and SRT. The group of tests that best differentiates Pb-
exposed workers from nonexposed workers were Simple Reaction
Time, Digit Symbol (WAIS) and Trail Making Test (Part A) with
long latency in reaction time contributing three times more to the
derived function than Digit Symbol (WAIS) or Trails A.
-------
Table AX6-3.4. Meta-analyses of Neurobehavioral Effects with Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Balbus-Kornfeld et al.
(1995)
Davis and Svendsgaard
(1990)
X
vo
Meyer-Baron and
Seeber (2000)
Goodman et al. (2002)
Reviewed 21 studies from 28 publications;
number of subjects ranged from 9-708.
Meta-analysis of 32 studies of nerve
conduction studies and Pb exposure.
Meta-analysis of studies with blood Pb
<70 ug/dL found 12 studies with comparable
test procedure and sufficient documentation
of results. Thirteen tests from the 12 studies
examined.
Meta-analysis of 22 studies with median
blood Pb <70 ug/dL, numbers of exposed
and unexposed workers given with scores
and dispersion on neurobehavioral tests.
Mean blood Pb in most
exposed group
28-68 ug/dL. Only 5
studies used a measure of
cumulative exposure or
absorption of Pb, 2 studies
used duration of exposure.
Exposed group
Range of mean blood Pb 31
to 49 ug/dL
Controls
Range of mean blood Pb 6
to 18 ug/dL
Exposed group
Range blood Pb 24 to
63 ug/dL
Unexposed group
Range blood Pb 0 to
28 ug/dL
Dexterity (17/21 studies) and executive or psychomotor 11/21
studies were the functional domains most commonly associated with
Pb. Age not adequately controlled in most studies, usually matching
means or medians. Intellectual abilities prior to exposure usually
adjusted for with education; however, Vocabulary, a measure of
overall intellectual ability still different between the groups.
The conclusion reached that evidence of effects from cumulative
exposure or absorption of Pb was inadequate.
Presented 41 effect sizes with the overall effect size for all studies
D = !0.369 (p # 0.001). All median nerves combined was D = 10.481
(p # 0.001) and for all ulnar nerves D = 10.211 (p # 0.001). The
median motor was most sensitive with an effect size of D = !0.553
(p # 0.001). Overall blood Pb was a weak measure of exposure for
the peripheral nervous system. Paradoxical association found effect
size smaller with increasing blood Pb but increased with duration of
exposure.
Block Design, Logical Memory, and Santa Ana had performance
deficits with small effect size. For Block Design the effect size was
comparable to changes observed with 20 yrs of aging. Aiming, SRT,
Trials A and B, Digit Span and Digit Symbol also had poorer
performance but the large variance for effect sizes suggest other
factors besides Pb exposure influenced performance. The authors
conclude, "that the evidence of neurobehavioral deficits at a blood Pb
of ^0 ug/dL is obvious."
Digit symbol and D-2 errors significant effect for fixed effects,
weighted random effects and unweighted random effects. Simple
reaction time, grooved pegboard, Trails A and B, picture completion
visual reproduction, eye-hand coordination and vocabulary had
significant effects for the fixed effects model only. The authors
conclude none of the individual studies were adequate or conclusive
of subclinical neurobehavioral effects of exposure to Pb as the
biological effects of blood Pb <70 ug/dL are inconsistent. (See
Schwartz et al. (2002) for comments).
-------
Table AX6-3.4 (cont'd). Meta-analyses of Neurobehavioral Effects with Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Schwartz et al. (2002)
Seeber et al. (2002)
X
Graves etal. (1991)
Letter to the Editor commenting on
shortcomings in the Goodman et al. (2002)
meta-analysis on studies of neurobehavioral
testing in workers occupationally exposed to
Pb.
A comparison of the two meta-analyses
Meyer-Baron and Goodman) performed to
evaluate recommendations of a German BEI
of 40 ug/dL.
A meta-analysis on 11 case-control studies of
Alzheimer's disease for occupational
exposure to solvents and Pb.
The six points regarding problems with the methodology included:
(1) no evaluation of quality of study design or statistical methods,
(2) data from poorly done and well done studies are combined,
(3) included 6 studies with no age adjustment and 3 with no
adjustment for education, (4) confounding of age and education
when addressed the variation across studies not discussed, (5) main
effect only examined exposed vs. nonexposed comparisons that are
known to have the lowest power, cannot evaluated dose-effect
relationships and have a tendency for selection bias, and (6) few of
the 22 studies included contributed to effect size.
Effect size calculated for 12 tests in two meta-analyses and 10 tests
from one meta-analyses found subtle impairments associated with
blood Pb between37 ug/dL and 52 ug/dL for Logical Memory,
Visual Reproduction, Simple Reaction Time, Attention Test 62,
Block Design, and Picture Completion, Santa Ana, Grooved
Pegboard and Eye-hand Coordination. Effect sizes related to age
norms between -40 to 50 yrs. For example, !3 score on Block
Design = 10 to 15 yrs; !3.5 score on Digit Symbol = 10 yrs; 121 score
on Cancellation d2 = 10 yrs; and +5 to +6 on Trails A = 10 to 20 yrs.
This analyses concluded that both meta-analyses supported
recommendation for German BEI of 40 ug/dL.
Four studies had data for Pb exposure with a pooled analysis of
relative risks for occupational Pb of 0.71 (95% CI: 0.36, 1.41).
The exposure frequencies were 16/261 for the cases and 28/337 for
the controls.
-------
Table AX6-3.5. Neurophysiological Function and Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Canada
Bleecker et al. (2005b)
New Brunswick
1992-1993
74 current smelter workers, mean age
44 (8.4) yrs, education 8 (2.8) yrs and
employment duration 20 (5.3) yr had current
perception threshold (CPT) measured for
large and small myelinated and unmyelinated
nerve fibers in the finger. Linear regression
modeled CPT on metrics of Pb dose after
adjusting for covariates. Interaction of Pb
dose and ergonomic stressor on peripheral
nerve function was assessed.
X
Mean (SD) blood Pb 26
(7.1) ug/dL
Mean (SD) IBL 891
(298.8)
ug-yr/dL
Mean (SD) TWA 42
(8.4)ug/dL
Mean (SD) tibia bone 40
(23.8) ug/g
5 metrics relating to IBL
cumulated only exposure
above increasing blood Pb
ranging from 20 to
60 ug/dL
Blood Pb and tibial bone Pb were not associated with any of the three
nerve fiber populations. IBL and TWA accounted for a significant
percentage of the variance only for the large myelinated nerve libers
(*R2 = 3.9%, *R2 = 8.7% respectively). The relationship of CPT and
TWA was curvilinear with a minimum at a TWA of 28 ug/dL.
Unique variance of CPT for large myelinated fibers explained by
different thresholds of IBL were IBL - 3.9%, p = 0.08; IBL20 - 5.8%,
p < 0.03, IBL30 - 7.8%, p < 0.02; IBL40, p < 0.005; IBL50,
p < 0.005; and IBL60, p < 0.005. IBL60 also explained significant
variance of CPT for small myelinated nerve fibers demonstrating an
increased impairment in peripheral nerve function. This effect on
myelinated sensory nerve fibers was enhanced when a measure of
ergonomic stress was added to the model for IBL60.
Europe
Kovalaetal. (1997)
Finland
60 workers in a Pb battery factory with a
mean age of 43 (9) yrs and mean exposure
duration of 16 (8) yrs. Nerve conduction
studies, vibration thresholds, and quantitative
EEG were performed. Relationship of Pb
exposure with peripheral nerve function and
quantitative EEG were examined by partial
correlation and regression analyses adjusting
for age.
Mean (SD) tibial Pb 26
(17)mg/kg
Mean (SD) calcaneal Pb
88(54)mg/kg
Mean (SD) IBL 546
(399)
ug-yr/dL
Mean (SD) TWA 34
(8.4) ug/dL
Mean (SD) maximum
blood Pb 53 (19) ug/dL,
Mean (SD) blood Pb 27
(8.4) ug/dL
The sensory amplitude of the median and sural nerves had a negative
correlation with IBL and duration of exposure that was not related to
age. Vibration threshold at the ankle related significantly to IBL and
duration of exposure after adjusting for age. Vibration threshold in
the linger was associated with blood Pb and blood Pb avgs over the
past three yrs. The alpha and beta frequencies were more present in
workers with higher long term Pb exposure such as tibial and
calcaneal, IBL and TWA. Overall historical blood Pb measures were
more closely associated with peripheral nerve function than bone Pb
concentrations. The study had no comparison group and did not
account for the effect of smoking and alcohol use or give their usage
in this population.
-------
Table AX6-3.5 (cont'd). Neurophysiological Function and Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia
Schwartz et al.
(200 la)
South Korea
1997-1999
X
to
Schwartz et al. (2005)
South Korea
1997-2001
804 workers from 26 different Pb using
facilities and 135 controls with a mean age of
40 ( 10.1) and 35 (9.l)yrs respectively, job
duration of 8 (6.5) and 9 (5.3) yrs
respectively, and education level 42 % and
69% completed high school respectively had
comparable alcohol and smoking use. Linear
regression used to compare vibration
threshold in Pb exposed and controls
controlling for potential confounders.
Longitudinal decline in neurobehavioral
performance examined in 576 of the above
group of Pb exposed workers who completed
3 visits at one yr intervals.
Mean age at baseline was 41 (9.5) yrs and
job duration 9 (6.3) yrs and 76% were men.
Compared to non-completers Pb workers
who completed 3 visits were 3.3 yrs older,
baseline mean blood Pb was 2.0 ug/dL
lower, on the job 1.6 yrs longer, 24% women
vs. 10% of noncompleters, and usually had
less than high school education. Models
examined short-term vs. long-term effects.
Final model had current blood Pb, tibia bone
Pb and longitudinal blood Pb and covariates.
Pb-exposed workers
Mean (SD) blood Pb
32 (15) ug/dL
Mean (SD) tibia bone Pb
37 (40.3) ug/g
Mean (SD) DMSA-
chelatable Pb
186(208.1)ug
collection)
(4h
Baseline mean (SD) blood
Pb 31 (14.2) ug/dL
Mean(SD)tibiaPb38
(43) ug/g
After adjustment for age, gender, education and height, tibia Pb but
not blood Pb was significantly associated with poorer vibration
threshold in the dominant great toe but not the finger (3 = 10.0020
[SE 0.0007], p < 0.01). These results contrast with those for
neurobehavioral measures (see above) performed in the same study
where tibial Pb was not a predictor of performance.
After adjustment for age, visit number, education, gender, height
(for vibration) and BMI (for grip strength and pinch) vibration
threshold in the dominant great toe and not the finger was associated
with tibia Pb (3 = 10.0006 [95% CI: 10.0010, 10.0002]) and
longitudinal blood Pb (3 = 10.0051 [95% CI: 10.0078, 10.0024])
in one model and blood Pb (3 = 10.0019 [95% CI: 10.0039,0.0001])
in another model.
-------
Table AX6-3.5 (cont'd). Neurophysiological Function and Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Chuang et al. (2000)
Taiwan
Chiaetal. (1996a)
Singapore
X
206 Pb battery workers, mean age 41 yrs,
with annual blood Pb for the previous five
yrs had vibration perception measured in
hand and foot. Relationship of Pb exposure
term and vibration perception threshold
assessed with multiple regressions, hockey
stick regression analysis after adjusting for
potential confounders.
72 workers in a Pb battery manufacturing
factory with a mean age of 30 yrs and
reference group of 82 workers had nerve
conduction studies and blood Pb performed
every 6 mos over the course of three yrs.
Only 28 Pb battery workers completed the
program. At the end of the first yr of the 82
workers in the comparison group only 26
remained and by yr 3 this had decreased to 4.
Mean nerve conduction values examined by
ANCOVA between the exposed and
reference after adjustment for age, ethnic
group, smoking and drinking habits.
Analysis of serial nerve conduction values
and blood Pb treated as a clustered sample
had the within-cluster regression coefficient
examined. The 28 exposed workers were
stratified by blood Pb level and the
relationship between nerve conduction values
and blood tested within the cluster.
Mean blood Pb 28 ug/dL
Mean blood Pb over past
5 yrs 32 ug/dL
Mean maximum blood Pb
39 ug/dL
Mean index of cumulative
exposure 425 ug-yr/dL
Mean TWA 32 ug/dL
Mean working duration
13 yrs and life span in
work 31%
Geometric mean blood Pb
concentrations for the 6
testing periods: 37,41,42,
40, 41, and 37 ug/dL
Overall range for blood Pb
16-73 ug/dL
After adjustment for age, sex, body height, smoking, alcohol
consumption, and use of vibrating hand tools, significant association
between mean blood Pb and mean TWA and vibration perception in
the foot were found. After adjustment for the covariates, a hockey
stick regression analysis of foot vibration threshold vs. mean blood
Pb concentration for 5 yrs found an inflection point around 30 ug/dL
with a positive linear relation above this point suggesting a potential
threshold.
The relationship between blood Pb levels and nerve conduction
values for the 28 exposed workers was significant for all outcomes
except median motor conduction velocity and ulnar sensory nerve
conduction velocity and ulnar sensory amplitude. The regression
correlation coefficients for blood Pb >40 ug/dL was significant for
all parameters except the median sensory conduction velocity and
for blood Pb <40 ug/dL there was no association with nerve
conduction values. Therefore the blood Pb level associated with
no change in nerve conduction studies was <40 ug/dL.
-------
Table AX6-3.5 (cont'd). Neurophysiological Function and Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Chiaetal. (1996b)
Singapore
Chuang et al. (2004)
Taiwan
X
Yokoyama et al.
(1998)
Japan
Extension of above study - 72 workers in Pb
battery manufacturing and 82 controls. Mean
duration of exposure 5.3 yrs.
181 Pb battery manufacture workers were
stratified by milk drinkers, n = 158 and non-
or rare mild drinkers n = 23. Mean age in the
two groups was 40 and 36 yrs and working
duration 10/8 yrs respectively. Peripheral
nerve evaluation was with current perception
threshold at 3 frequencies 5Hz = C fibers,
250 Hz = A-delta fibers and 2000 Hz = A-
beta fibers. Linear regression estimated the
association of CPT and Pb exposure variable
and adjustment of milk intake and potential
confounders.
17 gun-metal workers, mean age 48 yrs and a
20 controls with a mean age of 45 yrs had
distribution of conduction velocities (DC V)
measured and the maximum median sensory
conduction velocity (SVC) performed twice
at a yr interval. Group differences
controlling for confounders and dose-effect
relationships were examined.
Mean blood Pb 37 ug/dL
Mean cumulative blood Pb
137 ug-yr/dL
Blood Pb
Milk drinkers 25 ug/dL
Non or rare milk drinkers
30 ug/dL
TWA
Milk drinkers 28 ug/dL
Non or rare milk drinkers
32 ng/dL
IBL
Milk drinkers 316 ug-yr/dL
Non or rare mild drinkers
245 ug-yr/dL
Mean blood Pb 40 ug/dL
Mean mobilized Pb
(CaEDTA) in urine
1 mg/24 h
ANCOVA found significant differences for all nerve conduction
parameters except three for the ulnar nerve, after adjusting for age,
ethnic groups, smoking and drinking habits. There was no
significant correlation between blood Pb and cumulative blood Pb
with nerve conduction values after linear regression with adjustment
for confounders. When cumulative blood Pb was stratified- 12
workers <40 ug-yr/dL, 28 workers 40-300 ug-yr/dL, 21 workers
>300 ug-yr/dL ANCOVA found significant differences for
5 nerve conduction parameters. The strongest dose effect
relationship was for sensory nerve conduction velocity.
Age was significantly different but distributions of gender, smoking,
alcohol use, use of hand vibration tool, working history and height
were not different. Linear regressions found association of 5 Hz CPT
and 250 Hz CPT in hand and foot with blood Pb and TWA but not
IBL. However the protective effects of drinking milk was present for
all fiber populations only in the hands. This paper presents an
unusual finding of subclinical Pb neuropathy involving the
unmyelinated and small myelinated fibers. Toxic axonopathies
classically involve the large nerve fibers. The main group difference
may be related to other nutritional deficiencies associated with the
malabsorption syndrome that lead to the non-milk drinking status.
ANCOVA controlling for age and alcohol found mobilized Pb was
associated with significant slowing in the large nerve fibers while
blood Pb was not. Workers with increased change in mobilized Pb
over 1 yr interval (mean 0.44 mg/24hr) had significant reduction in
large fiber (V95) conduction velocity while those workers with less
change in mobilized Pb (0.08 mg/24hr) did not have significant
change in DCV or SVC. It appears that larger faster conducting
nerve fibers are susceptible to Pb and a measure of body burden
(readily mobilized Pb from soft tissue) is a stronger predictor of this
change than blood Pb.
-------
Table AX6-3.5 (cont'd). Neurophysiological Function and Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Heetal. (1988)
China
Niu et al. (2000)
China
X
40 workers in a Pb smelter with age range 20
to 45 yrs (no mean provided) and duration of
exposure 5.4 yrs. Fifty controls age 20 to
55 yrs. Nerve conduction studies examined
11 parameters. Student = s t-test examined
for differences between exposed and
controls.
44 Pb-exposed workers (17 men, 27 women)
from Pb printing houses, mean age 35 (4.9)
and education 9.3 (no SD)yrs and 34 controls
(19 men and 15 women), mean age 33 (7.4)
yrs and education 9.5 (no SD) yrs had nerve
conduction studies for maximal motor nerve
conduction velocity. ANCOVA controlling
for age, sex and education examined group
differences and linear regression for dose-
response relationship.
Mean blood Pb 40 ug/dL
Mean urinary Pb 71 ug/dL
Mean ALAU5 ug/dL
Pb workers
Mean blood Pb 29
(26.5) ug/dL
(8 workers blood Pb
exceeded 50 ug/dL)
Controls
Mean blood Pb 13
(9.9) ug/dL
(1 control blood Pb
exceeded 50 ug/dL)
There were no symptoms or signs of peripheral nerve disorder.
Both motor and sensory conduction velocities were slowed in the Pb
exposed groups. 10 nerve conduction parameters were significant in
the group with blood Pb >40 ug/dL and 6 parameters were
significant in the group with blood Pb <40 ug/dL. An unusual
finding in this study was the lack of age association with nerve
conduction values and therefore it was not controlled for in the
analyses.
Only 12 Pb exposed workers and 24 controls examined for NCV.
Left ulnar nerve was significantly slower but the left median and
right ulnar were faster in the Pb exposed and the right median was
slightly slower. This appears to be a finding of chance due to the
small n. For the Pb exposed group mean left ulnar CV was 52 while
the mean right ulnar CV was 59 while for the controls left ulnar CV
was 58 while the mean right ulnar CV was 55.
-------
Table AX6-3.6. Evoked Potentials and Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Canada
Bleecker et al. (2003)
New Brunswick
1992-1993
359 currently employed smelter workers, mean age 41
yrs, had brainstem auditory evoked potentials (BAEP)
measured. Relationship between absolute latencies
and interpeak latencies assessed using linear regression
after adjusting for potential confounders. Exposure
was assessed in cases with clinical abnormalities in
Wave I and I-V interpeak latency compared to those
workers with normal BAEP using post-hoc analysis.
Mean blood Pb 28 ug/dL
Mean TWA 39 ug/dL
Mean IBL 719 ug-yr/dL
Linear regression after the contribution of age found blood
Pb and TWA were significantly associated with Wave I
while IBL was significantly associated with Wave III and I-
III interpeak interval. Four groups created with increasing
abnormalities based upon clinical cut-off scores for Wave I
and I-V interpeak interval had similar age. blood Pb, TWA
and IBL were all significantly higher in the group with
prolonged Wave I and I-V interpeak interval compared
to the group with normal BAEP = s. These findings
support involvement of the brainstem and auditory nerve
with Pb exposure.
X
Oi
(^
Oi
Europe
Abbateetal. (1995)
Italy
Discalzi et al. (1992)
Italy
300 Pb exposed men ages 30 to 40 yrs in good health
with no other neurotoxic exposure had P100 latency
measured for visual evoked potentials (VEP) for 15
and 30 minute of arc. Groups created based upon
blood Pb had VEPS examined followed by linear
regression for each group.
49 Pb exposed workers and 49 age and sex matched
controls had BAEPs measured. Relationship of 6
BAEP outcome variables and Pb exposure examined
with analysis of variance and linear regression.
Blood Pb 17 to 60 ug/dL
range
Mean blood Pb for 4 groups
n = 39 23 ug/dL
n=113 30 ug/dL
n = 89 47 ug/dL
n = 59 56 ug/dL
Mean blood Pb 55 ug/dL
Mean TWA for previous
3 yrs 54 ug/dL
ANOVA of the blood Pb and PI 00 latencies were
significantly prolonged for 15 and 30 minutes of arc.
Linear regression found the association of blood Pb and
PI00 were significant in each group but the relationship
was not proportional (angular coefficient). Effect of blood
Pb on VEP began at 17-20 ug/dL. With age limited to one
decade, contribution from age was not a concern. Even
though no comparison group, careful screening ruled out
other medical and eye conditions and other potential
exposures.
Latencies for waves I, III, V and interpeak latencies, I-V, I-
III, and III-V were all significantly prolonged in the Pb-
exposed workers (p < 0.04). No significant association
found with linear regression between BAEP outcomes and
exposure variables. In those workers with TWA
>50 ug/dL, I-V latency was significantly prolonged
compared to workers with TWA <50 ug/dL.
-------
Table AX6-3.6 (cont'd). Evoked Potentials and Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Discalzietal. (1993)
Italy
22 battery storage workers, mean age 35 yrs and 22
control group, age and sex matched, with normal
hearing had BAEPs recorded. Latencies I and V and Pb
exposure examined by ANOVA after stratifying blood
Pb.
Mean blood Pb 48 ug/dL
Interpeak latency I-V was significantly prolonged in Pb
exposed workers (p = 0.001). No significant associations by
linear regression between I-V and Pb exposure. Stratifying
Pb exposed workers by blood Pb 50 ug/dL found I-V
interpeak latency significantly prolonged (p = 0.03) in
subgroup with higher blood Pb.
Latin America
Counter and Buchanan
(2002)
Ecuador
30 Pb-glazing workers, median age 35 yrs, had pure-
tone thresholds and BAEPs performed. Regression
analyses examined relations between auditory outcomes
and blood Pb.
Mean blood Pb 45 ug/dL
(range 11 to 80 ug/dL)
X
Sixty percent of the men and 20 percent of the women had
abnormal high-frequency thresholds, however there was no
significant relationship with blood Pb and pure tone threshold
at all frequencies. Analysis of BAEPs found agreement
between latencies for Waves I, III and V and peripheral
hearing status. Interpeak latencies were within normal limits
but no analysis provided with Pb exposure. Workers lived in
a Pb contaminated environment from discarded Pb-acid
storage batteries. Therefore a measure of chronic Pb
exposure may have been more appropriate.
Asia
Holdstein et al. (1986)
Israel
20 adults and 8 children (mean age 27 yrs, range 8-56 Mean blood Pb
yrs) accidentally exposed to Pb through food until one yr Adult 31 ug/dL
prior to measurement of BAEP. Children 22 ug/dL
10 mo avg blood Pb Adults
43 ug/dL
Children 36 ug/dL
In adults, latencies I, III and I-III and I-V interpeak intervals
were significantly longer than the control group (p < 0.05).
When group stratified by 10 mo avg blood Pb I-III interpeak
interval was longer in the high group. Age and blood Pb
were not studied due to few subjects. The I-III interpeak
interval reflects transmission in the lower brainstem and
Vlllth nerve.
-------
Table AX6-3.6 (cont'd). Evoked Potentials and Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Hirata and Kosaka
(1993)
Japan
X
oo
Murataetal. (1993)
Japan
41 Pb-exposed men from Pb-glass-based colors manufacturing
(n = 20), production of Pb electrode plates (n = 8), casting of Pb-
bronze (n = 4) and casting of Pb pipes and plates (n = 9) had mean
age 41 yrs, mean duration of exposure 13 yrs. A battery of tests
administered including radial nerve conduction study,
electroretinogram (ERG), visual evoked potential (VEP),
brainstem auditory evoked potential (BAER), and short-latency
somatosensory evoked potential (SSEP). Comparison group of 39
unexposed used only for BAER analysis by Student's t test.
Correlation and linear regression controlling for age examined the
relationship of Pb and the other variables.
22 gunmetal foundry workers with age range of 32 to 59 yrs and
work duration of 1 to 19 yrs and control group matched for age,
no chronic disease and no Pb exposure participated. No
significant difference between groups for age, height, skin
temperature, alcohol consumption, and yrs of schooling. The test
battery consisted of visual evoked potential (VEP), brainstem
auditory evoked potential (BAEP), short latency somatosensory-
evoked potential (SSEP), event related potential (P300) and EKG
R-R interval variability. Paired-sample t test examined for
differences between the matched groups. Dose-effect
relationships examined with partial correlation adjusting for age
and stepwise linear regression.
Mean (range) blood Pb
43 ug/dL (13-70)
Mean (range) TWA (based
upon previous 5 yrs)
43 ug/dL (13-70)
Mean (range) duration of
exposure 13 (0.6-29) yrs
Blood Pb 12 to 64 ug/dL
(no mean provided)
Significant partial correlation after adjusting for age
included TWA and radial motor conduction velocity,
blood Pb and sensory conduction velocity, exposure
duration and VEP, blood Pb and SSEP-N20.
Comparison of BAERs of 15 Pb exposed and 39
controls found interpeak interval III-V was
prolonged significantly. It is not clear why
comparison group only used for BAERs.
Considering the large number of variables examined
with three exposure terms some of the findings could
be by chance alone.
For VEPs, N75 and N145 were significantly
prolonged in the Pb exposed workers. N9-N13
interpeak latency of the SSEP was significantly
prolonged. BAEP latencies showed no significant
differences. P300 believed to reflect cognitive
function was prolonged in the Pb workers and
correlated with blood Pb, and PbU. Autonomic
nervous system effects were significantly diminished
for CVR.Rand for a measure of parasympathetic
activity C-CVRSA. Fifty percent of the outcome
variables showed significant group differences but
there is limited dose effect for any outcome within
the exposed group. Small sample size limited
conclusions with 20 outcome variables and 8
biomarkers of Pb exposure.
-------
Table AX6-3.7. Postural Stability, Autonomic Testing, Electroencephalogram, Hearing Thresholds, and
Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States
Dick etal. (1999)
U.S.
X
vo
145 workers from a secondary Pb smelter, mean
age 33 (8.7) and duration of employment 5 (4.8)
yrs and 84 comparison workers mean age 30 (9.3)
and duration of employment 4 (4.3) yrs had
postural sway testing performed. The analysis of
exposure with test conditions and covariates used
mixed models.
Pb workers
Mean(SD)bloodPb39
(8.5) ug/dL
Mean (SD) ZPP 55 (42.2) ug/dL
Mean (SD) CBL 230
(217.9) ng-yr/dL
Mean (SD) TWA 359
(8.5) ug/dL
Comparison workers
Mean (SD) blood Pb 2
(1.7) ug/dL
The postural sway test had 6 conditions that varied the
challenge to the vestibular and proprioceptive afferents and
visual system. Only blood Pb had a significant effect
primarily on the one leg condition after the effects of the
covariates age, height, mass, and race. For the left leg,
exposure slope estimate for area (b = 0.0067, t = 3.88,
p = 0.0001) and length (b = 0.0046, t = 4.11, p = 0.0001)
were significant. For the right leg only the exposure slope
estimate for length (b = 0.0033, t = 3.02, p = 0.0029) was
significant. Dose effect was only significant when Pb
workers were combined with comparison workers. If
comparison workers with blood Pb level below 12 ug/dL
removed no significant exposure effect was found.
Europe
Kovalaetal. (1997)
Finland
60 workers in a Pb battery factory with a mean
age of 43 (9) yrs and mean exposure duration of
16 (8) yrs. Quantitative EEG were performed.
Relationship of Pb exposure with quantitative
EEG were examined by partial correlation and
regression analyses adjusting for age.
Mean (SD) tibial Pb 26
(17)mg/kg
Mean (SD) calcaneal Pb
88(54)mg/kg
Mean (SD) IBL 546
(399)
ug-yr/dL,
Mean (SD) TWA 34 (8.4) ug/dL,
Mean (SD) maximum blood Pb
53 (19) ug/dL
Mean (SD) blood Pb 27
(8.4) ug/dL
The alpha and/or beta frequencies were more present in
workers with higher long term Pb exposure such as tibial
(p < 0.05) and calcaneal (p < 0.05), IBL (p < 0.01) and
TWA (p < 0.05). Slow alpha in workers was believed to
correlate with increased episodes of 'microdrowsiness'.
The study had no comparison group and did not account for
the effect of smoking and alcohol use or give their usage in
this population.
-------
Table AX6-3.7 (cont'd). Postural Stability, Autonomic Testing, Electroencephalogram, Hearing Thresholds, and
Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia
Iwataetal. (2005)
Japan
X
Oi
Yokoyama et al.
(1997)
Japan
Chiaetal. (1994a)
Singapore
Chiaetal. (1996c)
Singapore
121 workers from a battery recycling plant
and 60 age matched comparison group, mean
age 46 (11) yrs. Height, body weight, body
mass index, and alcohol use was similar in
both groups. Pb group had significantly
more smokers. ANCOVA used to evaluate
postural sway after controlling for age,
height, and smoking and drinking status.
Benchmark dose level was calculated as the
95% lower confidence limit of the
benchmark dose.
49 chemical workers exposed to Pb stearate,
mean age 48 (1.3) yrs and 23 controls, mean
age 47 (2.5) had postural sway evaluated.
ANCOVA examined group differences after
adjusting for covariates.
60 Pb storage workers, mean age 32 (7.7) yrs
and 60 controls, mean age 35 (7.4) had
postural sway parameters measured.
ANCOVA used to examine group differences
after adjusting for covariates. Linear
regression examined relationship between Pb
exposure and postural sway.
The same 60 Pb storage workers as above
and 60 control had postural sway data
examined for contribution of cumulative
blood Pb fractionated over 10 yrs of
exposure.
Mean (SD) blood Pb 40
(15) ug/dL
Referent
Not done
Mean (SD) blood Pb 18
(l.O)ngML
Mean (SD) maximum
blood Pb 48 (3.8) ug/dL
Mean (SD) TWA 24
(1.3) ug/dL
Mean (SD) Cumulative
blood Pb 391
(48.2) ug-yr/dL
Pb workers
Mean (SD) blood Pb 36
(11.7) ug/dL
Controls
Mean (SD) blood Pb 6
(2.4) ug/dL
Pb workers
Mean (SD) blood Pb 36
(11.7) ug/dL
Controls
Mean (SD) blood Pb 6
(2.4) ug/dL
Except for sagittal sway, all postural sway parameters with eyes open
were significantly larger in Pb workers. Blood Pb level in workers
was significantly associated with to sagittal sway at 1-2 Hz and 2-4
Hz with eyes open, and sagittal and transversal sways at 1-2 Hz and
2-4 Hz with eyes closed. The mean benchmark dose level of current
blood Pb level for postural sway was 14.3 ug/dL for the linear model
and 14.6 ug/dL for the K power model.
There were significant increases in sway in all directions at high and
low frequencies with eyes open and eyes closed (p < 0.05).
Regression analysis found blood Pb associated with sway in the
anterior-posterior direction, 0.5-lHz (0.321, p = 0.03), l-2Hz (0.313,
p = 0.04) and TWA associated with right to left sway (0.326,
p = 0.02) after adjustment for the covariates age, height, weight and
alcohol consumption. The authors conclude that change in the
vestibule-cerebellum is affected by blood Pb while in the anterior
cerebellar lobe is affected by past Pb exposure.
Computerized postural sway measurements found Pb workers
have poorer postural stability that increased with eyes closed
(p < 0.01). Regression analysis adjusting for age, height, and
weight found no significant association with blood Pb.
The Pb exposed group had significantly poorer performance on all
postural sway parameters with eyes closed compared to controls after
adjusting for height, weight, age and drinking habits (p < 0.01).
All postural sway parameters with eyes closed were significantly
associated with IBL for the 2 yrs prior to testing (n = 23, p < 0.05).
-------
Table AX6-3.7 (cont'd). Postural Stability, Autonomic Testing, Electroencephalogram, Hearing Thresholds, and
Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Ratzon et al. (2000)
Israel
Teruyaetal. (1991)
Japan
X
Oi
Ishidaetal. (1996)
Japan
63 Pb battery workers, mean age 39 (8.7) yrs
and 48 controls mean age 36 (11.8) yrs,
matched for age with similar sex and
education, had postural control measured.
Group differences examined with t test.
Dose-effect relations assessed with
Pearson = s correlation coefficients. Linear
regression done with exposure category as
major predictor.
172 Pb exposed workers, mean age 34
(18.4-57.4) yrs had cardiac autonomic
nervous system evaluated by R-R intervals
variation with respiration measured.
128 workers in the ceramic painting industry,
58 men, mean age 55 (11.7) yrs and
70 women, mean age 52 (9.2) yrs had
measures of sympathetic function by
variations in R-R interval on EKG and
changes in finger blood flow with postural
changes using Doppler flowmetry.
Correlation analyses and linear regression
examined relationship of finger blood flow
and Pb exposure after adjusting for
covariates.
Mean past blood Pb
38 ug/dL
Mean yrs employed 11
Cumulative Pb determined
by avg blood Pb H yrs
employed
Mean (range) blood Pb 36
(5-76) ug/dL
Men
Mean (SD) blood Pb 17
(2.1) ug/dL
Mean (SD) ALAD% 61.6
(28.3)%
Women
Mean (SD) blood Pb 11
(1.7) ug/dL
Mean (SD) ALAD% 72.6
(20.8)%
Using a computerized sway measurement system the exposed
workers had significantly increased mean body oscillations with eyes
closed (p < 0.01) and head tilted forward (p < 0.001). Partial
correlation adjusting for education, coffee consumption, hrs of sleep
and estimate of health was significant only for total Pb exposure and
increased body oscillations with head tilted forward (3 = 2.25,
p = 0.0089). In order to maintain balance Pb exposed workers
required increased oscillations when visual and vestibular inputs
were altered.
Age adjustment controlled for by use of ratios of predicted to
observed values. A significant dose related decrease of R-R interval
variation during deep breathing was present in 132 workers with
stable blood Pb over the past yr (p < 0.01). This finding was more
prominent in younger workers with blood Pb 330 ug/dL but a mild
decrease present at blood Pb 320 ug/dL. A decrease in R-R interval
variation indicates decreased cardiac parasympathetic function.
22% had blood Pb >20 ug/dL, and 43% had ALAD% <60%. The
46 workers in the lowest group with blood Pb <10 ug/dL had
ALAD% >80% equivalent to nonoccupational exposure and
therefore served as the control group. Blood Pb (3 = 0.205,
p = 0.02), smoking (3 = -0.464, p < 0.01), and BMI (3 = 0.213,
p = 0.01) were significant predictors of change in finger blood flow
with postural change. Decrease in change of finger blood flow is
compatible with a peripheral sympathetic nerve impairment.
-------
Table AX6-3.7 (cont'd). Postural Stability, Autonomic Testing, Electroencephalogram, Hearing Thresholds, and
Occupational Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Niu et al. (2000)
China
X
Oi
44 Pb-exposed workers (17 men, 27 women)
from Pb printing houses, mean age 35 (4.9)
and education 9.3 (no SD) yrs and 34
controls (19 men and 15 women), mean age
33 (7.4) yrs and education 9.5 (no SD) yrs
had autonomic nervous system examined.
ANCOVA controlling for age, sex and
education examined group differences and
linear regression for dose-response
relationship.
Pb workers
Mean (SD) blood Pb 29
(26.5) ng/dL
(8 workers blood Pb
exceeded 50 ug/dL)
Controls
Mean (SD) blood Pb 13
(9.9) ug/dL
(1 control blood Pb
exceeded 50 ug/dL)
Niu et al. (2000) examined autonomic nervous system in 44 Pb
exposed workers, mean blood Pb 29 ug/dL, and 34 controls, mean
blood Pb, 13 ug/dL. Linear regression found association between
blood Pb and decreased R-R interval with valsalva (FAT 2.349,
p < 0.05) and duration of Pb exposure and decreased R-R interval
with deep breathing (F/T 3.263, p < 0.01) after adjusting for age, sex,
education, smoking and drinking. In the same study, quantitative
EEG found significant abnormalities in the Pb-exposed workers,
dominant low amplitude in 59%, dominant beta frequency in 42%
and abnormalities in 81%.
to
-------
Table AX6-3.8. Occupational Exposure to Organolead and Inorganic Lead in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States
Schwartz et al. (1993)
U.S.
Stewart etal. (1999)
U.S.
X
Oi
Two hundred and twenty-two current
employees that manufactured tetraethyl Pb
participated in a study to determine if there
was impairment on a neurobehavioral battery
associated with a measure of cumulative
exposure to organic and inorganic Pb derived
from 12 yrs of air sampling. Mean age was
44 (8.7) yrs, education 13 (1.7) yrs.
543 former organolead workers, mean yrs
since last exposurelS, examined for ongoing
neurobehavioral impairment related to past
Pb exposure. Thirty-eight % were age 60 or
older, predominantly white, 93% had at least
a high school degree. Linear regression
assessed the relationship between Pb dose
and neurobehavioral function adjusting for
the covariates.
Mean (SD) cumulative Pb
exposure (inorganic and
organic) 869 (769) ug-yr/m
Mean (SD) yrs of exposure
13(9.5)
Mean (SD) tibial Pb 14
(9.3) ug/g
Mean (SD) peak tibial bone
Pb (extrapolated back using a
clearance half-time of Pb in
tibia of 27 yrs) 24
(17.4) ug/g
Mean (SD) DMSA chelatable
Pb 19 (17.2) ug (urine
collected for 4 hrs)
Exposure was divided into 4 groups with the lowest for yrs of
exposure and cumulative Pb exposure serving as the reference group.
After adjustments for premorbid intellectual ability, age, race, and
alcohol consumption, cumulative Pb exposure had differential
association poorer performance in many cognitive domains but most
often in manual dexterity and verbal memory/learning. Performance
on tests associated with exposure was 5 to 22% lower in the highest
groups when compared with the low exposure reference group.
Peak tibial Pb was a significant predictor of poorer performance on
Vocabulary (3 = !0.063, p = 0.02), serial digit learning (3 = !0.043,
p = 0.04), RAVLT trial 1 (3 = !0.054, p = 0.03), RAVLT recognition
(3 = 10.019, p = 0.03), Trails B (3 = !0.002, p = 0.03), finger tapping
nondominant (3 = !0.042, p = 0.02), Purdue pegboard dominant
(3 = !0.043, p = 0.00), nondominant (3 = 10.49, p = 0.00), both
(3 = !0.038, p = 0.00), assembly (3 = 10.133, p = 0.00), and Stroop
(3= 10.014, p = 0.00).
Current tibial Pb had similar associations - Vocabulary (3 = 0.103,
p = 0.04), Digit Symbol (3 = !0.095, p = 0.05), finger tapping
dominant (3 = 10.87, p = 0.02), finger tapping nondominant
(3 = 0.102, p = 0.00), Purdue Pegboard dominant (3 = !0.065,
p = 0.01), nondominant (3 = 10.091, p = 0.00), both (3 = !0.068,
p = 0.00), assembly (3 = 10.197, p = 0.03 ), and Stroop (3 = 0.017,
p = 0.01).
DMSA-chelatable Pb was only significantly associated with choice
reaction time (3 = !0.001, p = 0.01).
-------
Table AX6-3.8 (cont'd). Occupational Exposure to Organolead and Inorganic Lead in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States (cont'd)
Stewart et al. (2002)
U.S.
X
Oi
Balbusetal. (1997)
U.S.
Balbusetal. (1998)
U.S.
From the above group of former organolead
workers 535 were re-examined twice or four
times over a four yr period. Also a
nonexposed control group of 118 had repeat
examinations. Mean age at first visit
exposed/controls 56 (7.4)759 (7.0),
percentage with at least a high school
education 66/71.2.
222 organolead manufacturing workers,
mean age 44 (8.7) yrs and 62 nonexposed
referents, mean age 43 (10) yrs performed
simple visual reaction time (SVRT). Linear
regression examined relationship between Pb
exposure and mean RT, median RT and
standard deviation of RT after controlling for
covariates.
A second publication further examined the
above data for relationship of interstimulus
interval (ISI) and Pb exposure.
1 st examination
Mean (SD) blood Pb 5
(2.7) ug/dL
Mean (SD) tibia Pb 14
(9.3) ug/g
Mean (SD) peak tibia Pb
23 (16.5) ug/g
Mean (SD) exposure duration
8 (9.7)yrs
Mean (SD) duration since last
exposure 16 (11.7) yrs
Mean (SD) blood Pb 20
(9.5) ug/dL
Mean (SD) peak urine Pb level
143(130)ug/L
Same as above
On 17 of 19 neurobehavioral tests, former organolead workers
demonstrated greater annual decline in adjusted test scores
compared to controls with significant differences for Rey complex
Figure copy, RAVLT Trial 1 and RAVLT recognition. Annual
declines in performance showed greater age-related change in Pb
workers compared to controls for block design, digit symbol,
serial digit learning, finger tapping and Trails A. Blood Pb did not
predict annual change scores but peak tibial Pb did for symbol
digit, Rey Complex Figure delayed recall, RAVLT trial 1,
RAVLT delayed recall, Purdue pegboard (1 measure) and the
Stroop. For these 6 tests it was determined that an increase of
15.7 ug/g bone mineral of peak tibia Pb was equivalent in its
effect on annual test decline to 5 more yrs of age at baseline.
Authors conclude that data supports ongoing cognitive decline
associated with past occupational exposure to Pb.
Short ISIs of 1-3 seconds had no relationship with Pb exposure
while ISIs of 4-6 seconds were significantly associated with blood
Pb (3 = 0.06 [SE 0.02], p = 0.02 along with ISIs of 7-10 seconds
(3 = 0.05 [SE 0.02], p = 0.03). ISIs 7-10 seconds with peak urine
Pb levels (3 = 64.29 [SE 21.86], p < 0.01).
-------
Table AX6-3.8 (cont'd). Occupational Exposure to Organolead and Inorganic Lead in Adults
Reference, Study
Location, and Period Study Description
Pb Measurement
Findings, Interpretation
United States (cont'd)
Stewart et al. (2002)
U.S.
X
Oi
Tassleretal. (2001)
U.S.
Bollaetal. (1995)
U.S.
Mitchell etal. (1996)
U.S.
Population as described in Stewart et al.
(1999) and Schwartz et al. (2000b). Data
on 20 neurobehavioral tests from 529
former organolead workers were
evaluated to determine if the previously
described relationship with bone Pb
levels is influenced by the apolipoprotein
E (ApoE) genotype.
490 former organolead workers, mean
age 58 (7.5) yrs. The peripheral nervous
system was examined with sensory
pressure thresholds, and pinch and grip
strength.
190 current workers in organolead
manufacturing (from the 222 described in
Schwartz et al., 1993) mean age 45 (8)
yrs compared to 52 referents, mean age
45 (8) yrs and 144 solvent exposed
workers, mean age 42 (8) yrs.
58 organolead workers, self-selected for
a clinical evaluation. Mean age 45 (7.1)
yrs.
Mean (SD) blood Pb 5
(2.6) ng/dL
Mean (SD) DMSA-chelatable Pb
19 (16.3) ng
Mean (SD) current tibia Pb
15(9.4)ug/g
Mean (SD) peak tibia Pb 24
(17.6) ug/g
IH found organic Pb was 65 to
70% of exposure in production
area.
Mean (SD) weighted avg blood
Pb 24 (9.4) ug/dL
Mean (SD) blood Pb 19
(6.5) ug/dL
Mean (SD) lifetime blood Pb 26
(9.1)ng/dL
Mean (SD) lifetime urine Pb 51
(18.8) ng/L
In 20 linear regression models, coefficients for the ApoE and tibia Pb
interaction term were negative in 19 with significance reached for digit
symbol (3 = 10.109 [SE 0.054], p # 0.05), Purdue pegboard dominant
(3 = 0.068 [SE 0.028], p # 0.05) and complex reaction time (3 = !0.003
[SE 0.001], p#0.05) and borderline significance existed for symbol digit
(3 = !0.046 [SE 0.026], p # 0.10), Trails A (3 = !0.303, [SE 0.164]
p # 0.10) and Stroop (3 = 10.013 [SE 0.008], p # 0.10). The slope of the
relation between tibia Pb and neurobehavioral outcome was more
negative in those individuals with at least one s4 allele than individuals
without this allele. It is suggested that the presence of one Apo-s-4 allele
increases the risk of persistent central nervous system effects of Pb.
No strong association was found between Pb biomarkers and measures
of sensory and motor function after adjusting for age. The authors
attributed the findings to decreased sensitivity of the peripheral nerves in
this dose range of inorganic Pb or the possibility of differential repair in
the peripheral nervous system compared to the central nervous system.
Pb and solvent exposure associated with adverse effects on tests of
manual dexterity. When compared to the solvent group Pb exposure had
greater impairment on memory and learning and less on executive/motor
tests. An elevated neuropsychiatric score was present in 43% of the Pb
group, 15% of the solvent and 7% of the referent group.
The most common symptoms were memory loss 74%, joint pain 56%,
trouble sleeping 54%, irritability 51%, paresthesia 49%, fatigue 49%,
nightmares 35%, moodiness 28%, headaches 21% and depression 21%.
Of the 31 workers receiving nerve conduction studies, 29% were normal,
carpal tunnel syndrome 36%, cubital tunnel syndrome 3%, median
neuropathy 3%, ulnar neuropathy 23%, mononeuropathy in lower
extremity 5%, tarsal tunnel syndrome 7% and sensorimotor
polyneuropathy 36%. 39 workers had neurobehavioral evaluation with
64% had abnormal tests of which 46% were considered to be consistent
with a toxic exposure.
-------
Table AX6-3.9. Other Neurological Outcomes Associated with Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States
Louis et al. (2005)
New York
X
ON
ON
Louis et al. (2003)
New York
Kamel et al. (2002)
Massachusetts
63 cases of essential tremor
(ET) and 101 controls,
similar for age, 67 (16.6) and
65(11.1) yrs, education,
gender and ethnicity were
examined for interaction of
blood Pb and ALAD gene
polymorphisms and increased
odds of ET.
100 cases of ET and 143
controls matched for age, sex,
and ethnicity.
The relationship between
blood Pb and ET was
examined.
109 cases of ALS and 256
controls matched for age, sex
and region of residence
examined the relation of Pb
and ALS.
ET
Mean (SD) blood Pb 4 (2.2) ng/dL
Controls
Mean (SD) blood Pb 3 (1.5) ng/dL
2 ET cases but no controls had blood Pb
ET
Mean blood Pb 3 ng/dL
Controls
Mean blood Pb 2 ng/dL
Cases/controls
Mean (SD) blood Pb 5 (0.4) / 3 (0.4)
3 cases and no controls had blood Pb >10 ng/dL
Mean (SD) patella Pb 21 (2.1) / 17 (2.0) ng/g
5 cases and 1 control had patella Pb levels
>50 ng/g
Mean (SD) tibia Pb 15 (1.6)/ 11 (1.6) ng/g
2 cases and no controls had tibia Pb >50 ng/g.
Of the 63 ET cases 18 (29%) vs. 17 (17%) of 101 controls had an
ALAD2 allele (OR = 1.98 [95% CI: 0.93, 4.21]; p = 0.077). When
log blood Pb was examined by presence of ALAD2 allele in ET, log
blood Pb was highest in ET cases with and ALAD2 allele,
intermediate in ET cases without an ALAD2 allele and lowest in
controls (test for trend, 3 = 0.10; p = 0.001). When ALAD2 allele
was present, blood Pb was significantly associated with odds of ET
(OR = 80.29 [95% CI: 3.08, 2.096]; p = 0.008). This increased
odds of ET with an ALAD2 allele was 30 times greater than in an
individual with only an ALAD1 alleles. In the highest log blood Pb
tortile, ALAD2 allele was present in 22% of ET cases and 5% of
controls. It was proposed that increased blood Pb along with the
ALAD2 allele could affect the cerebellum and thereby increase the
risk of tremor.
Ten cases and 7 controls had bone Pb levels measured that were
significantly correlated with blood Pb suggesting that higher blood
Pb may have occurred in the past. Total tremor score was
correlated with blood Pb (r = 0.14, p = 0.03). Logistic regression
adjusting for age and current cigarette smoking found the odds ratio
for ET was 1.19(95% CI: 1.03, 1.37) per unit increase in blood Pb.
Blood Pb was higher in those 39 ET cases with no family history.
Both current and lifetime prevalence of occupational Pb exposure
was the same in ET cases and controls but those with history of
occupational exposure did have a higher blood Pb than those
without this history (median, 3.1 ng/dL vs. 2.4 ng/dL, p = 0.004).
Increased risk of ALS was found for history of occupational Pb
exposure (adjusted OR =1.9 [95% CI: 1.1, 3.3]) increased lifetime
days of exposure (adjusted OR = 2.3 [95% CI: 1.1, 4.9]).
Association of blood Pb and ALS (adjusted OR = 1.9 [95% CI: 1.4,
2.6]). Elevation in both blood Pb and patella and tibia bone Pb was
found in ALS cases though the precision of these measurements
was questioned (Patella Pb adjusted OR = 3.6 [95% CI: 0.6, 20.6]
and tibia Pb adjusted OR = 2.3 [95% CI: 0.4, 14.5]). Therefore,
this study found Pb exposure from historical questionnaire data and
biological markers associated with ALS.
-------
Table AX6-3.9 (cont'd). Other Neurological Outcomes Associated with Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
X
Oi
United States (cont'd)
Kamel et al. (2003)
Massachusetts
Armonetal. (1991)
Minnesota
As above, the same data was used to
determine the associations of ALS with
polymorphism in ALAD and the vitamin D
receptor (VDR) and the influence of
genotype.
Same as above
A case-control design with 47 ALS patients,
mean age 61 with involvement of upper and
lower motor neurons and 201 controls, mean
age 62. For the Pb exposure analysis 45 male
matched pairs were examined.
Lifetime exposure to Pb of
200 hrs or more (yrs on job x
hrs spent per wk)
The ALAD2 allele was associated with a 2-fold increase risk of ALS
after adjustment for the covariates, age, sex, region, education and
physical activity adjusted (OR = 1.9 [95% CI: 0.60, 6.3]).
Additionally adjusting for blood Pb strengthened the association of
ALAD2 and ALS risk adjusted (OR = 3.6 [95% CI: 0.9, 15]). This
was not found for bone Pb or occupational history of Pb exposure
(patella-adjusted OR = 2.1 [95% CI: 0.61, 6.9]; tibial-adjusted (OR =
2.2 [95% CI: 0.66, 7.3]; occupational history-adjusted
(OR = 2.4 [95% CI: 0.67,8.7]). VDR was not associated with Pb or
ALS risk.
Of 13 discordant pairs for Pb exposure, 11 were in ALS patient. The
relative risk was 5.5 (95% CI: 1.44, 21.0). A dose-response was
weakened by 3 controls with highest lifetime exposure. Men with
ALS worked more often at blue collar jobs and significantly more
time welding (p < 0.01). These results expanded a prior pilot study
that found a higher incidence of heavy metal exposure in ALS cases.
Europe
Chancellor et al. A case-control design 103 ALS patients from
(1993) the Scottish Motor Neuron Disease Register
Scotland and matched community controls.
1990-1991 Differences in potential occupational
exposures were determined between cases
and controls.
Gunnarsson et al. A case-control study of 92 cases of MND
(1992) and 372 controls. MND included ALS,
Sweden progressive bulbar paresis (PBP), and
1990 progressive muscular atrophy (PMA).
Relation of MND to risk factors including
occupational exposure examined.
Exposure to Pb obtained by
lifetime employment history
from Office of Population and
Censuses and Surveys.
Physician's record review and
direct interview questionnaire.
Exposure information
obtained by self-administered
questionnaire.
Odds ratio for manual labor in ALS patients was 2.6 (95% CI: 1.1,
6.3). Occupational exposure to Pb was more common in ALS
patients (OR = 5.7 [95% CI: 1.6, 30]).
Exposure to heavy metals primarily from welding had an increased
Mantel-Haenszel OR = 3.7 [95% CI: 1.1, 13.0].
-------
Table AX6-3.9 (cont'd). Other Neurological Outcomes Associated with Lead Exposure in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Guidetti et al. (1996)
Italy
Vincetietal. (1997)
Italy
A retrospective incidence, prevalence, and
mortality survey of ALS in northern Italy
was performed.
19 ALS cases, mean age 66 (14) yrs and
39 controls, mean age 64 (12.9) yrs.
X
Oi
Mean air Pb 3 ug/m in
1975 to 1 ug/m3 in 1985;
blood Pb in monitored
children decreased 18, 14,
and 11 ug/dL in same time
period.
Sporadic ALS
Mean (SD) blood Pb 13
(6.8) ng/dL
Controls
Mean (SD) blood Pb
ll(4.4)ng/dL
The area studied had documented Pb pollution for yrs. Based upon
79 cases incidence and prevalence rate were comparable to the
surrounding area.
There were no cases familial ALS. Blood Pb between ALS cases
and controls was not significantly different. Blood Pb was associated
with disability due to ALS but no support was found for involvement
of Pb in the etiology of sporadic ALS.
OO
-------
ANNEX TABLES AX6-4
AX6-69
-------
Table AX6-4.1. Renal Effects of Lead in the General Population
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States
Kim etal. (1996)
Boston, MA
1979-1994
X
459 men in the Normative Aging Study; periodic
exams every 3-5 yrs.
Mean serum creatinine at baseline
1.2mg/dL
Random effects modeling, adjusting for baseline age,
time since initial visit, body mass index, smoking
status, alcohol ingestion, education level,
hypertension (defined as blood pressure >160 or 95
mm Hg or anti-hypertensive medication use), and, in
longitudinal analysis, baseline serum creatinine and
time between visits.
Mean (SD) blood Pb at
baseline
9.9 (6.1) ug/dL
Blood Pb levels from stored
red blood cells were adjusted
for hematocrit; the assay and
adjustment procedure were
validated against freshly
collected samples. Storage
tubes were shown to be Pb
free.
Cross-sectional
Positive association between log transformed blood Pb
and concurrent serum creatinine. 10-fold higher blood Pb
level associated with 0.08 mg/dL higher serum creatinine
(95% CI: 0.02,0.13).
Association stronger in participants with lower peak blood
Pb levels. 3 coefficient (95% CI) in the 141 participants
whose peak blood Pb #10 ug/dL: 0.06 (95% CI: 0.023,
0.097).
Longitudinal
Positive association between log transformed blood Pb
and change in serum creatinine over subsequent follow-up
period in participants whose peak blood Pb was #25 ug/dL
3 coefficient 0.027 (95% CI: 0.0, 0.054)
Slope of age-related increase in serum creatinine steeper in
group with highest quartile of time weighted avg Pb
exposure compared to the lowest quartile.
-------
Table AX6-4.1 (cont'd). Renal Effects of Lead in the General Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
United States (cont'd)
Muntner et al. (2003)
U.S.
1988-1994
X
Blood Pb levels measured in 15,211 adult subjects enrolled in
the NHANES III study.
Study cohort representative of U.S. population; non-Hispanic
African Americans, Mexican Americans, the elderly and
children over-sampled to allow stable estimates in these groups.
Hypertension defined as blood pressure 3140 and/or 90 mm Hg
and/or current antihypertensive medication use. Based on
evidence of interaction between blood Pb and hypertension, the
population was stratified by hypertension for further analysis.
4,813 hypertensives; 10,398 normotensives.
Elevated serum creatinine (%)
Defined as 399th percentile of each race-gender specific
distribution for healthy young adults [age 20-39 without
hypertension or diabetes].
11.5% (hypertensives)
1.8% (normotensives)
Chronic kidney disease (%)
Chronic kidney disease defined as GFR <60 mL/min/1.73 m2;
estimated by MDRD equation (Levey et al. [1999]).
10 % (hypertensives)
1.1% (normotensives)
Multiple logistic regression.
Age, race, gender, diabetes, systolic blood pressure, smoking
status, history of cardiovascular disease, body mass index,
alcohol consumption, household income, marital status, and
health insurance.
Mean (SD) blood Pb
4.21 (0.14) ug/dL
(hypertensives)
3.30 (0.10) ug/dL
(normotensives)
Higher odds ratios of both increased serum creatinine
and chronic kidney disease by quartile of blood Pb in
hypertensives but not in normotensives.
Hypertensives
Odds ratios for elevated serum creatinine after full
adjustment:
% Odds ratio (95% CD
7.2 1.00
12.1 1.47(1.03,2.10)
12.4 1.80(1.34,2.42)
16.3 2.41(1.46,3.97)
Blood Pb (range,
Quartile 1 (0.7 to 2.4)
Quartile 2 (2.5 to 3.8)
Quartile 3 (3.9 to 5.9)
Quartile 4 (6.0 to 56.0)
p < 0.001 for chi-squared test for trend.
Odds ratios for chronic kidney disease after full
adjustment:
Blood Pb %
Quartile 1 6.1
Quartile 2 10.4
Quartile 3 10.8
Quartile 4 14.1
Odds ratio (95% CD
1.00
1.44(1.00,2.09)
1.85(1.32,2.59)
2.60(1.52,4.45)
p < 0.001 for chi-squared test for trend.
Associations were similar when Pb was entered as a log
transformed continuous variable.
In non-hypertensives, higher blood Pb was associated
with a higher prevalence of chronic kidney disease, but
not elevated serum creatinine, in diabetics.
-------
Table AX6-4.1 (cont'd). Renal Effects of Lead in the General Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
to
United States (cont'd)
Paytonetal. (1994)
Boston, MA
1988-1991
Shadick et al. (2000)
Boston, MA
1991-1996
Blood Pb levels measured in 744 men enrolled in the Mean blood Pb
Normative Aging Study.
Serum creatinine
1.3mg/dL
Measured creatinine clearance
88.2 mL/min
Calculated creatinine clearance
71 mL/min
Multiple linear regression adjusting for age, body
mass index, analgesic and diuretic use, alcohol
consumption, smoking status, systolic/ diastolic blood
pressure.
777 participants in all male Normative Aging Study.
8.1 ug/dL
Blood Pb levels below the
limit of detection of 5 ug/dL
were receded as 4 ug/dL (n
not stated).
Mean blood Pb
5.9 ug/dL
Mean tibia Pb
20.8 ug/g bone mineral
Mean patella Pb
30.2 ug/g bone mineral
In blood Pb negatively associated with In measured
creatinine clearance (3 = !0.04 [95% CI: !0.079, !0.001]).
10 ug/dL higher blood Pb associated with a 10.4 mL/min
lower creatinine clearance.
Borderline significant associations (p < 0.1) between
blood Pb and both serum creatinine (3 = 0.027; neither SE
nor CI provided) and estimated creatinine clearance
(3 = !0.022; neither SE nor CI provided).
A significant association between patella Pb and uric acid
(3 = 0.0007 [95% CI: 0.001, 0.013]; p = 0.02) was found,
after adjustment for age, BMI, diastolic blood pressure,
alcohol ingestion, and serum creatinine. Borderline
significant associations between tibia (p = 0.06) and blood
Pb (p = 0.1) and uric acid were also observed. Notably
these associations were significant even after adjustment
for blood pressure and renal function, providing further
evidence that low level Pb increases uric acid. Fifty-two
participants had gout; Pb dose was not associated with risk
for gout.
-------
Table AX6-4.1 (cont'd). Renal Effects of Lead in the General Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
United States (cont'd)
Tsaih et al. (2004)
Boston, MA
1991—2001
X
448 men enrolled in the Normative Aging Study.
Baseline Serum Creatinine
1.3mg/dL
Longitudinal analysis of data from 2 evaluations a
mean of 6 yrs apart.
Annual change in serum creatinine = (follow-up
serum creatinine - baseline serum creatinine) / yrs of
follow-up.
Covariates assessed = age, age squared, body mass
index, hypertension (defined as blood pressure 3160
or 95 mm Hg or physician diagnosis with use of
antihypertensive medication), diabetes (defined as use
of oral hypoglycemic drugs or insulin or reported
physician diagnosis), smoking status, alcohol
consumption, analgesic use, and, in longitudinal
models, baseline serum creatinine and its square.
Six percent and 26% of subjects had diabetes and
hypertension, at baseline, respectively.
Mean (SD) baseline blood Pb
6.5 (4.2) ug/dL
Mean (SD) baseline tibia Pb
21.5 (13.5) ug/g bone mineral
Mean (SD) baseline patella Pb
32.4 (20.5) ug/g
Mean blood Pb levels and serum creatinine decreased
significantly over the follow-up period in the group. Pb
dose not associated with change in creatinine overall.
Significant interaction of blood and tibia Pb with diabetes
in predicting annual change in serum creatinine.
3 (95% CI) for natural In baseline blood Pb 0.076 (0.031,
0.121) compared to 0.006 (10.004, 0.016) for non-
diabetics.
3 (95% CI) for natural In baseline tibia Pb 0.082 (0.029,
0.135) compared to 0.005 (10.005, 0.015) for non-
diabetics.
Significant interaction of tibia Pb with hypertensive status
in predicting annual change in serum creatinine.
3 (95% CI) for natural In baseline tibia Pb 0.023 (0.003,
0.019) compared to 0.0004 (!0.001, 0.002) for non-
hypertensives.
Follow-up serum creatinine was also modeled separately
in longitudinal analyses; diabetes modified the association
between baseline tibia Pb and follow-up serum creatinine.
-------
Table AX6-4.1 (cont'd). Renal Effects of Lead in the General Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
United States (cont'd)
Wu et al. (2003a)
Boston, MA
1991-1995
X
709 men enrolled in the Normative Aging Study.
Serum creatinine
1.2mg/dL
Calculated creatinine clearance
71.3 mL/min
Serum uric acid
6.5 mg/dL
Multiple linear regression, adjusting for age, body
mass index, blood pressure or HTN (depending on
model), and alcohol ingestion. Uric acid models also
adjusted for serum creatinine, other outcome models
adjusted for smoking status and analgesic medication
use.
Mean (SD) blood Pb
6.2 (4.2) ug/dL
Mean (SD) tibia Pb
22 (13.4) ug/g bone mineral
Mean (SD) patella Pb
32.1 (19.5) ug/g bone mineral
Significant inverse association between patella Pb and
creatinine clearance.
3= !0.069,SE not provided
Borderline significant (p = 0.08) inverse association
between tibia Pb and creatinine clearance. Borderline
significant (p = 0.08) positive associations between tibia
and patella Pb and uric acid. No Pb measure significantly
associated with serum creatinine.
ALAD gene polymorphism also assessed. 114
participants had the ALAD2 variant allele (7 were
homozygous). None of the three renal outcomes differed
by genotype. Effect modification by genotype on the
association between tibia Pb and serum creatinine was
observed; the beta coefficient (and slope) was greater in
the group with the variant allele (3 = 0.002 [SE not
provided]; p = 0.03).
Effect modification of borderline significance (p<0.\)on
relations between of patella and tibia Pb with uric acid was
observed; this was significant in participants whose patella
Pb levels were above 15 |j,g/g bone mineral (3 = 0.016 [SE
not provided]; p = 0.04 ). Similar to the serum creatinine
model, patella Pb was associated with higher uric acid in
those with the variant allele. Genotype did not modify Pb
associations in models of estimated creatinine clearance.
-------
Table AX6-4.1 (cont'd). Renal Effects of Lead in the General Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
Europe
Alfven et al. (2002)
Sweden
OSCAR Study
Date not provided
Akesson et al. (2005)
Women's Health in
the Lund Area Study,
1999-2000
N = 479 men, 542 women. All resided near two Mean blood Pb
battery plants, 117 participants were current or former 0.16 umolg/L men
workers from plants. 0.11 umolg/L women
Renal outcome = urinary al microglobulin.
Multiple linear regression.
Age, smoking status, gender (by stratification),
blood cadmium.
N = 820 women
Renal outcomes = GFR (estimated with cystatin C),
estimated creatinine clearance, urinary NAG and a!
microglobulin.
Multiple linear regression.
Age, body mass index, diabetes, hypertension, and
regular use of nephrotoxic drug, blood and urinary
cadmium (in separate models), smoking status
(by stratification).
Mean blood Pb
2.2 ug/dL
Blood Pb not associated with urinary 0.1 microglobulin
(regression performed separately in men and women).
Blood Pb negatively associated with estimated GFR and
creatinine clearance. No associations with NAG or 0.1
microglobulin.
3 (95% CI) for association between blood Pb (ug/dL) and
estimated creatinine clearance (mL/min) is !1.8
-------
Table AX6-4.1 (cont'd). Renal Effects of Lead in the General Population
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
De Burbure et al.
(2003)
France
Study date not provided
X
Oi
-!j
Oi
600 adults (399 exposed, 201 age and gender matched controls).
400 children (200 exposed, 200 age and gender matched controls).
Age ranged from 8.5 to 12.3 yrs.
Exposure from residence near smelters.
Exclusion criteria for children included obesity, diabetes, and puberty;
for adults included pregnancy, cancer, diabetes, and kidney disease.
Serum creatinine
1.43 mg/dL (adult male controls)
1.38 mg/dL (exposed adult males)
1.33 mg/dL (adult female controls)
1.26 mg/dL (exposed adult females)
Urinary 3?-microglobulin
68.16 ug/g creatinine (adult male controls)
76.29 ug/g creatinine (exposed adult males)
63.79 ug/g creatinine (adult female controls)
71.98 ug/g creatinine (exposed adult females)
87.8 ug/g creatinine (boy controls)
97.3 ug/g creatinine (exposed boys)
88.2 ug/g creatinine (girl controls)
94.8 ug/g creatinine (exposed girls)
Urinary NAG
1.12 lU/g creatinine (adult male controls)
1.24 lU/g creatinine (exposed adult males)
0.98 lU/g creatinine (adult female controls)
1.28 lU/g creatinine (exposed adult females)
2.29 lU/g creatinine (boy controls)
1.70 lU/g creatinine (exposed boys)
2.21 lU/g creatinine (girl controls)
1.07 lU/g creatinine (exposed girls)
Urinary RBP
82.8 ug/g creatinine (adult male controls)
85.8 ug/g creatinine (exposed adult males)
83.42 ug/g creatinine (adult female controls)
95.81 ug/g creatinine (exposed adult females)
94 ug/g creatinine (boy controls) 99 ug/g creatinine (exposed boys)
110 ug/g creatinine (girl controls) 109 ug/g creatinine (exposed girls)
Renal outcome measures also included urinary total protein, albumin,
transferrin, and brush border antigens.
Multiple linear regression adjusting for age, sex, body mass index,
area of residence, smoking, alcohol ingestion, mercury, cadmium and
urinary creatinine level.
Geometric mean blood
Pb
7.13 ug/dL (adult male
controls)
6.78 ug/dL (exposed
adult males)
4.17 ug/dL
(adult female controls)
5.25 ug/dL
(exposed adult females)
3.42 ug/dL (boy
controls)
4.22 ug/dL (exposed
boys)
2.74 ug/dL (girl
controls)
3.69 ug/dL (exposed
girls)
Adults
Mean blood Pb level higher in exposed women but not
men. None of the renal outcomes analyzed showed
any significant difference between exposed and
unexposed groups. After adjustment for covariates,
blood Pb was not associated with any renal outcomes.
Children
Mean blood Pb levels higher in exposed. The highest
geometric mean blood cadmium was 0.52 ug/L. None
of the renal outcomes were significantly higher in
exposed. After adjustment for covariates, blood Pb
was not associated with any renal outcomes, however,
blood cadmium was positively associated with NAG.
This association was present in both control and
exposed areas.
Participants with extremes of urinary creatinine
excluded from data analyses. As a result, number of
subjects in data tables substantially less than in study.
-------
Table AX6-4.1 (cont'd). Renal Effects of Lead in the General Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
Europe (cont'd)
Factor-Litvak et al.
(1993)
Kosovo, Yugoslavia
1985-1986
Staessen et al. (1990)
London, England
Study date not
provided
1447 Yugoslavian women in prospective study of
environmental Pb exposure and pregnancy.
Exposure from Kosovska Mitrovica with a Pb smelter,
refinery, and battery plant. Controls from Pristina, 25
miles away.
Renal outcome = Proteinuria assessed with a dipstick.
Exclusionary criteria included HTN (n = 37 excluded,
similar blood Pb levels to remaining participants).
Multiple logistic regression adjusting for age (linear
and quadratic), height (linear and quadratic), cigarette
smoking, gestational age (linear and quadratic), daily
milk consumption, number of previous live births, avg
weekly meat consumption, hemoglobin level and
ethnic group.
531 London civil servants (398 male, 133 female).
Exclusionary criteria = occupational exposure to
heavy metals.
Serum creatinine
1.10mg/dL(men)
0.88 mg/dL (women)
Mean blood Pb
17.1 ug/dL (582 exposed)
5.1 ug/dL (865 controls)
Mean blood Pb
12.4 ug/dL (men)
10.2 ug/dL (women)
Proteinuria (negative, trace, or 31+)
Exposed = 16.2% negative, 74.1% trace and 9.7% with
31+ proteinuria. Controls = 32.4% negative, 60.6% trace
and 7.1% with 31+ proteinuria. Authors attributed overall
high proportion of proteinuria to pregnancy.
Higher blood Pb associated with increased odds ratio for
trace and 31+ proteinuria.
Comparing women in upper 10th percentile of exposure to
lower 10th percentile of exposure, adjusted odds ratios
(95% CI) for trace and 31+ proteinuria was 2.3 (1.3,4.1)
and 4.5 (1.5, 13.6), respectively.
Limitations = limited renal outcomes assessed.
After removal of 2 outliers, the study found no significant
correlation between serum creatinine and log blood Pb in
No correlation between serum creatinine and log blood Pb
in women.
Limitations = lack of adjustment in data analysis, limited
Pb dose and renal outcome assessment, loss of power by
analyzing gender in separate models.
-------
Table AX6-4.1 (cont'd). Renal Effects of Lead in the General Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Staessen et al. (1992)
Belgium
1985-1989
X
oo
Blood Pb levels were measured in 1981 adult subjects
(965 males, 1016 females) enrolled in the Cadmibel
study of general Belgian population in four cadmium
polluted and unpolluted areas.
Inclusion criteria included age 320 yrs and residence
in one of four study areas for 38 yrs. Participants
were randomly selected from the study areas;
participation rates were 78% in the two rural areas but
only 39% in the urban areas (one area from each
category was known to be cadmium polluted).
Measured creatinine clearance
99 mL/min (males)
80 mL/min (females)
Calculated creatinine clearance
80 mL/min (males)
69 mL/min (females)
Multiple linear regression.
Covariates assessed included age, age squared, gender
(by stratifying), body mass index, blood pressure,
ferritin level, smoking status, alcohol ingestion, rural
vs. urban residence, analgesic and diuretic use, blood
and urinary cadmium, diabetes, occupational exposure
to heavy metals, and gamma glutamyl transpeptidase.
Blood Pb
11.4ug/dL(males)
7.5 ug/dL (females)
Zinc protoporphyrin also
assessed.
After adjustment, log transformed blood Pb negatively
associated with measured creatinine clearance.
3 coefficient (95% CD
!9.5(!0.9, 118.1) males
112.6 (!5.0, !20.3) females
A 10 fold increase in blood Pb associated with a decrease
in creatinine clearance of 10 and 13 mL/min in men and
women, respectively.
Log transformed blood Pb also negatively associated with
calculated creatinine clearance.
3 coefficient (95% CD
113.1 (!5.3, !20.9)males
130.1 (123.4, !36.8) females
Log transformed zinc protoporphyrin negatively
associated with measured and calculated creatinine
clearances and positively associated with serum 32-
microglobulin in both sexes and with serum creatinine in
Blood Pb positively associated with serum 32-
microglobulin in men.
-------
Table AX6-4.1 (cont'd). Renal Effects of Lead in the General Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Asia
Lin etal. (1993)
Taiwan
Study date not
provided
X
vo
Satarug et al. (2004)
Bangkok, Thailand
Study date not
provided
123 adults living near a Pb battery factory for more
than 10 yrs.
Divided into 3 groups by proximity to the factory.
Group 1 <500 m (n = 49)
Group 2 1000-1500 m (n = 47)
Group 3 farther away (n = 27)
Exclusionary criteria included history of exposure to
nephrotoxicants and nephrotoxicant medications, such
as NSAIDs.
24 h urinary NAG excretion
3.3U/day(Groupl)
2.4 U/day (Group 3)
Multiple linear regression with adjustment for age.
118 Thai adults (53 men, 65 women).
Renal outcome measures noted below, also include
BUN and total urinary protein.
Serum creatinine
0.94 mg/dL (males)
0.66 mg/dL (females)
Urinary NAG
4.4 U/g creatinine (males)
4.6 U/g creatinine (females)
Urinary 3?-microglobulin
51 ug/g creatinine (males)
29 ug/g creatinine (females)
Mean blood Pb
16.6 ug/dL (Group 1)
13.5 ug/dL (Group 2)
7.9 ug/dL (Group 3)
EDTA diagnostic chelation
(done in Group 1)
126.1 ug/24hrs
Mean "serum" Pb
0.42 ug/dL (males) 0.3 ug/dL
(females)
Note - cannot determine from
article if actually serum Pb
(much less commonly used) or
blood Pb.
Mean urinary Pb
1.3 ug/g creatinine (males)
2.4 ug/g creatinine
(females)
Urinary cadmium also
assessed.
Significantly higher prevalence of abnormal urinary NAG
found in the exposed group 1 compared to the control group 3
(55.6% compared to \\.\%;p<0.00\). However,mean
NAG not significantly higher in Group 1.
In all 45 participants in whom both measures were obtained,
EDTA chelatable Pb was not correlated with urinary NAG
excretion. However, a significant correlation between EDTA
chelatable Pb #200 ug/24 hrs and urinary NAG excretion was
observed in the 39 participants in this group. Further
evaluation with multiple linear regression, adjusting for age,
revealed a 3 = 0.034 (95% CI: 0.009, 0.059); p = 0.01.
No correlation noted between blood Pb level and urinary
NAG.
Limitations = small sample size, plots indicate potential for
influential outliers.
In men, urinary Pb excretion correlated only with urinary
protein at borderline significance (r = 0.22, p < 0.06).
In women, urinary Pb excretion correlated with urinary NAG
(r = 0.5, p < 0.001), protein (r = 0.31, p = 0.01) and
32-microglobulin (r = 0.36, p = 0.002) excretion.
After adjustment for urinary cadmium, only association
between urinary Pb and NAG remained significant.
Three urinary renal biomarkers correlated with urinary
cadmium, although only at borderline significance (p = 0.06)
for 32-microglobulin.
Limitations = small sample size, Pb dose assessment since
only urine Pb used in renal analyses, limited data analysis.
-------
Table AX6-4.1 (cont'd). Renal Effects of Lead in the General Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
oo
o
Asia (cont'd)
Satarug et al. (2004)
Bangkok, Thailand
Study date not
provided
96 Thai men.
Subjects subdivided into nonsmokers (n = 53), current
smokers (n = 27), and ex-smokers (n = 16).
Renal outcome measures noted below, also include
BUN and total urinary protein.
Serum creatinine
0.94 mg/dL (nonsmokers)
0.93 mg/dL (smokers)
0.96 mg/dL (ex-smokers)
Urinary NAG
4.4 U/g creatinine (nonsmokers)
4.2 U/g creatinine (smokers)
3.8 U/g creatinine (ex-smokers)
Urinary 37-microglobulin
51 ug/g creatinine (nonsmokers)
95 ug/g creatinine (smokers)
98 ug/g creatinine (ex-smokers)
Mean "serum" Pb
0.42 ug/dL (nonsmokers)
0.9 ug/dL (smokers)
0.61 ug/dL (ex-smokers)
Mean urinary Pb
1.3 ug/g creatinine
(nonsmokers)
1.4 ug/g creatinine (smokers)
1.4 ug/g creatinine (ex-
smokers)
Urinary cadmium
also assessed.
Urinary Pb correlated with urinary protein (r = 0.49,
p < 0.01) in smokers and at borderline significance
(r = 0.22; p = 0.06) in never smokers. Also correlated
with 32-microglobulin in ex-smokers at borderline
significance (r = 0.39; p = 0.06).
Urinary cadmium correlated with urinary NAG in current
and never smokers and at borderline significance
(p = 0.07) in ex-smokers. Also correlated with urinary
protein and 32-microglobulin in current smokers and, at
borderline significance, in never smokers.
Limitations = small sample size, Pb dose assessment since
only urine Pb used in renal analyses, limited data analysis.
Middle East
Mortada et al. (2004)
Egypt
Study date not
provided
68 Egyptian men (35 smokers, 33).
Renal outcomes included serum creatinine, BUN, and
32- microglobulin and urinary albumin, NAG, 32-
microglobulin, alkaline phosphatase, and y-glutamyl
transferase.
Mean blood Pb
14.4 ug/dL (smokers)
10.2 ug/dL (nonsmokers)
Pb also measured in urine,
hair, and nails.
Also measured cadmium, and
mercury.
Blood and hair Pb levels significantly higher in smokers as
compared to nonsmokers.
No significant differences in renal outcome measures by
smoking status. No correlation between exposure indices
and renal outcome measures.
Limitations: small sample size, data analysis - no
adjustment.
-------
Table AX6-4.2. Renal Effects of Lead in the Occupational Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
United States
Smith etal. (1995)
U.S.
Study date not
provided
691 construction workers.
96 participants with the ALAD2 allele.
Mean blood Pb
7.8 ug/dL (ALADI 1)
7.7 ug/dL (ALAD12 or 22)
Higher mean BUN (p = 0.03) in participants with the
ALAD2 allele compared to those with the ALAD11
genotype. However, after adjustment for age, alcohol
ingestion, and blood Pb, the association was no longer
significant. Effect modification was not evaluated.
X
oo
Europe
Bergdahl etal. (1997)
Sweden
Study date not
provided
89 Pb workers; 7 had the ALAD2 allele.
34 controls; 10 had the ALAD2 allele.
Median blood Pb
31.1 ug/dL in Pb workers
with AL AD 11
28.8 ug/dL in Pb workers
with AL AD 12 or 22
3.7 ug/dL in control workers
with AL AD 11
3.7 ug/dL in control workers
with AL AD 12 or 22
Higher crude mean serum creatinine (p = 0.11) in
participants with the ALAD2 allele compared to those
with the ALAD11 genotype. Adjusted data not presented.
-------
Table AX6-4.2 (cont'd). Renal Effects of Lead in the Occupational Population
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
C35 |J.g/dL and exposure >1 yr were required
in exposed workers. Participants with renal disease, renal
risk factors, such as diabetes or regular analgesic medication
use, or urinary cadmium >2 |j,g/g creatinine, were excluded.
Multiple linear regression; adjusted for urinary creatinine
and, in some cases, BMI.
Serum creatinine
1.02 mg/dL (workers)
1.03 mg/dL (controls)
Battery of more than 20 renal biomarkers obtained
including:
RBP
68 ug/L (workers)
64 ug/L (controls)
NAG
1.56 U/L (workers)
1.21 U/L (controls)
Mean blood Pb
48.0 ug/dL (workers)
16.7 ug/dL (controls)
Mean duration of Pb
exposure = 14 yrs
Urinary cadmium also
measured as potential
confounder.
Serum creatinine was not increased in Pb workers
compared to controls; associations between Pb dose and
serum creatinine, if assessed, were not specifically
reported.
In all 82, blood Pb:
-associated with thromboxane B2(3 = 0.36, p< 0.01).
-negatively associated with 6-keto-prostaglandin F! ^^
(3= 10.179, p< 0.01).
Zinc protoporphyrin positively associated with sialic acid
excretion.
NAG increased in Pb workers but associated with urinary
cadmium.
Limitations = sample size, potential for healthy worker
bias, limited statistical analysis.
-------
Table AX6-4.2 (cont'd). Renal Effects of Lead in the Occupational Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
oo
Europe (cont'd)
Coratellietal. (1988)
Study location and
date not provided;
authors from Italy
Pels etal. (1994)
Study location and
date not provided
Garcon et al. (2004)
France
Study date not
provided
20 Pb battery factory workers.
20 controls.
12 mo longitudinal study.
Renal outcomes = urinary alanine aminopeptidase, NAG
and lysozyme.
81 male Pb workers; 45 age matched controls.
Extensive exclusionary criteria.
Renal outcomes
Serum creatinine
Glomerular markers = 6-keto-prostaglandin FI alpha,
thromboxane B2, and fibronectin.
Proximal tubular markers = brush border antigens (BBA,
BB50, HF5) and intestinal alkaline phosphatase.
Distal nephron markers = prostaglandin E2, prostaglandin
F2 alpha-
35 male nonferrous metal smelter workers.
Renal outcomes = armicroprotein, 32-microglobulin,
retinol binding protein, a and ic glutathione S transferases
(GST).
Oxidative stress markers also measured.
All variables log transformed.
Initial mean blood Pb
47.9 ug/dL (workers)
23.6 ug/dL (controls)
Median blood Pb
42.1 ug/dL (workers)
7.0 ug/dL (controls)
Mean blood Pb
39.6 ug/dL
Mean blood cadmium
"g/L
5.
Mean urine cadmium
4.7 ug/g creatinine
NAG and lysozyme higher in exposed compared to
controls throughout study. A statistically significant
decline in urinary NAG was noted in association with a
one mo period of decreased occupational exposure in the
Pb workers. NAG correlated with time of exposure
(nonlinear) but not blood Pb. Clinical renal function
measures were not studied.
Serum creatinine similar in exposed compared to controls.
Medians of several markers statistically greater in workers
compared to controls. After adjustment for age and
erythrocyte protoporphyrin, several renal marker outcomes
showed "some relation" to blood Pb. The table of these
data shows r and r2 but not beta coefficients making the
actual statistical method used unclear.
Study limitations include lack of adjustment in statistical
analysis, potential for healthy worker bias.
Correlations between urine Pb and cadmium and the renal
outcomes assessed (not blood Pb or cadmium).
Significant positive correlations included:
urine Pb and a GST (p < 0.01)
urine cadmium and RBP (p < 0.05)
Also, urine cadmium and 8-OHdG negatively correlated.
Limitations = use of urine Pb, lack of adjustment for other
covariates, sample size.
Significant correlations between blood Pb and two
markers of oxidative stress were observed along with a
correlation between blood cadmium and one marker of
oxidative stress.
-------
Table AX6-4.2 (cont'd). Renal Effects of Lead in the Occupational Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Gennartetal. (1992)
Study location and
dates not provided;
authors from Belgium
98 Pb workers and 85 controls from initial group of 221.
Renal outcomes = urinary retinol-binding protein, 3-2
microglobulin, albumin, NAG, and serum creatinine and
3-2 microglobulin and estimated creatinine clearance.
Exclusionary criteria included lack of exposure to other
metals or solvents, urinary cadmium <2 ug/g creatinine,
neurologic or renal disease, certain medications, blood Pb
level >40 ug/dL (workers) and <40 ug/dL for controls.
Mean blood Pb
51 ug/dL (workers)
20.9 ug/dL (controls)
Mean duration of employment
10.6 yrs
X
Mean renal outcomes were not different in workers
compared to controls. Prevalence of abnormal
values was not greater in workers compared to
controls. An analysis of variance, in all
participants, by categorical blood Pb, duration of
employment, ZPP, and delta-aminolevulinic
acid showed no relations with any of the outcomes
(data were not shown).
Limitations include high Pb levels in controls,
adjustment only for age in statistical analysis,
potential healthy worker bias.
oo
-------
Table AX6-4.2 (cont'd). Renal Effects of Lead in the Occupational Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Gerhardsson et al.
(1992)
Sweden
Study date not
provided
X
oo
70 current Pb smelter workers.
30 retired Pb smelter workers.
31 active and 10 retired truck assembly workers (controls).
Renal outcomes = serum creatinine, urinary 3-2
microglobulin, NAG, and albumin, clearances of
creatinine, albumin, relative albumin, 3-2 microglobulin
and relative 3-2 microglobulin.
Blood Pb measured annually since 1950; time integrated
blood Pb index = summation of annual blood Pb
measurements.
Median blood Pb
31.9 ug/dL (current Pb workers)
9.9 ug/dL (retired Pb workers)
4.1 ug/dL (current control workers)
3.5 ug/dL (retired control workers)
Median time integrated blood Pb index
369.9 ug/dL (current Pb workers)
1496.1 ug/dL (retired Pb workers)
Median calcaneus Pb
48.6 ug/g bone mineral
(current Pb workers)
100.2 ug/g bone mineral
(retired Pb workers)
Median tibia Pb
13.0 ug/g bone mineral
(current Pb workers)
39.3 ug/g bone mineral
(retired Pb workers)
3.4 ug/g bone mineral
(current control workers)
12.0 ug/g bone mineral
(retired control workers)
Creatinine clearance was higher in Pb workers;
p-values not reported for this or other median
values between Pb workers and controls.
In current Pb workers, blood Pb was positively
correlated with urinary 3-2 microglobulin and time
integrated blood Pb index was correlated with
NAG (data not shown).
Strengths include assessment of cumulative Pb,
inclusion of former workers.
Limitations = statistical analysis, lack of power
by stratifying.
-------
Table AX6-4.2 (cont'd). Renal Effects of Lead in the Occupational Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
Oi
oo
Oi
Europe (cont'd)
Pergandeetal. (1994)
Study location and
date not provided;
research team is
German
Restek-Samarzija
etal. (1996)
Croatia
Study date not
provided
Restek-Samarzija
etal. (1997)
Croatia
Study date not
provided
82 male Pb workers.
44 age-matched healthy male volunteers without known
exposure to Pb and living "in areas distant from the
exposed people."
Renal outcomes = serum creatinine and 32 microglobulin,
urinary albumin and 14 other early biological effect
markers.
Exclusion criteria included prescription medication use
and many diseases; 11 workers and 3 controls excluded.
74 patients treated between 1951 and 1989 for at least one
episode of Pb poisoning (53 occupational, 23
environmental).
Renal outcomes = measured creatinine clearance
(collection time not specified), GFR assessed with
99mTc-diethylenetriaminepenta-acetic acid (DTPA)
clearance.
38 patients with occupational Pb poisoning, 23
occupationally exposed workers.
Renal outcomes = serum creatinine, measured creatinine
clearance (collection time not specified), hippuran renal
flow.
Mean blood Pb
42.1 ug/dL (workers)
7.0 ug/dL (controls)
Erythrocyte protoporphyrin
also measured.
Mean blood Pb
1.5 umol/L (poisoned
workers)
1.6 umol/L (workers)
Serum creatinine and 32 microglobulin not increased in
exposed compared to control participants; correlations
with these outcomes not reported. Blood Pb and/or
erythrocyte protoporphyrin correlated with 9 of the
urinary renal outcomes.
Study limitations include lack of adjustment in
statistical analysis, potential for healthy worker bias,
potential for differences between exposed and control
groups.
Number of past Pb poisonings negatively correlated
with creatinine and DTPA clearances.
Creatinine clearance significantly lower in poisoned
group.
-------
Table AX6-4.2 (cont'd). Renal Effects of Lead in the Occupational Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Rods etal. (1994)
Belgium
Study date not
provided
X
oo
76 Pb smelter workers (including 21 participants from
Cardenas et al. [1993] [Dr. Roels, email communication])
68 controls.
All males.
Matched for age, sex, socioeconomic status, residence, and
workshift characteristics.
Extensive exclusionary criteria included renal disease,
analgesic abuse, chronic medication for gout, diabetes,
occupational exposure to other nephrotoxicants, and prior
EDTA chelation.
Renal outcomes included serum creatinine and urea
nitrogen, measured creatinine clearance, NAG, RBP,
serum and urinary 32-microglobulin, as well as other renal
early biological effect markers.
Measured creatinine clearance
121.3 mL/min/1.73 m2 (workers)
115.5 mL/min/1.73 m2 (controls)
Multiple linear regression, adjusted for age, urinary
cadmium, hypertension, serum gamma-glutamyl
transpeptidase, smoking, exposure status (exposed vs.
control), and interaction between exposure variables and
hypertension.
Mean blood Pb
43.0 ug/dL (workers)
14.1 ug/dL (controls)
Mean tibia Pb
66 ug/g bone mineral
(workers)
21 ug/g bone mineral
(controls)
Urinary cadmium also
measured.
Creatinine clearance measured before and after an oral
protein load to determine if eicosanoid changes in
Cardenas et al. (1993) had clinical implications (Acute
protein ingestion causes increased renal perfusion and
transient hyperfiltration thought to be mediated by
changes in vasodilator prostanoids. Therefore, it was
hypothesized that, if the changes noted in Cardenas
et al. (1993) were clinically significant, the
hyperfiltration response would be diminished in the Pb
workers.).
All participants had normal baseline creatinine
clearances (>80 mL/min/1.73 m2). Both control and
Pb-exposed workers showed a similar increment in
creatinine clearance after protein load.
However, mean creatinine clearance was statistically
higher in Pb workers compared to controls. Log tibia
Pb was positively correlated with log measured
creatinine clearance in the combined group
(3 = 0.0319, SE not provided).
This was unexpected as the change in eicosanoids
found in the initial study would not seem to result in
vasodilatation with increased GFR. Unfortunately, it
was not possible to measure eicosanoid levels in the
follow-up study. No other significant associations
between Pb measures and renal outcomes were
observed. Urinary cadmium associated with NAG.
-------
Table AX6-4.2 (cont'd). Renal Effects of Lead in the Occupational Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
oo
oo
Europe (cont'd)
Verschoor et al.
(1987)
Study location and
date not provided;
authors from The
Netherlands
155 Pb workers (Pb battery and plastic stabilizer).
126 control industrial workers.
Workers with renal disease, HTN, prescription
medications excluded.
Renal outcomes = BUN, serum creatinine, uric acid,
32-microglobulin, and RBP, and urinary RBP, NAG,
albumin, uric acid, 32-microglobulin, IgG, and total
protein. Urine protein electrophoresis performed on subset
(n = 25).
Cadmium in blood and, in a subset of exposed workers, in
urine was also assessed due to this exposure in one plant
each from which Pb exposed and control workers were
drawn.
Mean blood Pb
47.5 ug/dL (workers)
8.3 ug/dL (controls)
Zinc protoporphyrin
also used as Pb dose measure.
Mean renal outcomes in all participants shown by
categorical Pb levels. NAG and RBP higher at blood
Pb levels >21 ug/dL compared to those below this
level (statistical significance not reported). Serum 32-
microglobulin and urinary total protein lower at blood
Pb levels >21 ug/dL compared to those below this
level (again, statistical significance not reported).
In simple linear regression models of log transformed
urinary total protein, urinary RBP, NAG and serum 32-
microglobulin, higher log transformed blood Pb was
significantly associated with lower serum 32-
microglobulin and higher RBP and NAG.
A matched pair analysis of 55 pairs matched for age
within 5 yrs, smoking, socioeconomic status, and
duration of employment found no differences in renal
outcomes between exposed and controls.
Limitations = lack of adjustment, potential for healthy
worker bias, occupational cadmium exposure
(including in controls) not adequately adjusted.
Latin and South America
Cardozo dos Santos
etal. (1994)
Study location and
date not provided;
authors from Brazil
166 Pb battery workers.
60 control workers.
Renal outcomes = serum creatinine, NAG, urine albumin,
and total urinary protein, y-glutamyl-transpeptidase,
alanine-aminopeptidase.
Median blood Pb
36.8 ug/dL (workers)
11.6 ug/dL (controls)
Significant results.
Median NAG higher in exposed group (p< 0.001).
Blood Pb level and duration of exposure correlated
with NAG in combined group (Spearman's correlation
coefficients = 0.32 and 0.22, respectively, p < 0.001 for
both).
No results mentioned for serum creatinine.
Limitations = statistical analysis (no regression for
renal outcomes).
-------
Table AX6-4.2 (cont'd). Renal Effects of Lead in the Occupational Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
oo
VO
Latin and South America (cont'd)
Pinto de Almeida
etal. (1987)
Northeast Brazil
Study date not
provided
52 primary Pb smelter workers (had to have worked > 5
yrs on production line).
44 control paper mill workers in same city.
All males.
Renal outcomes = BUN, serum creatinine, uric acid,
proteinuria, creatinine clearance.
Only 2 participants excluded for medical reasons.
Mean blood Pb
64.1 ug/dL (workers)
25.5 ug/dL (controls)
Also measured zinc
protoporphyrin and delta-
aminolevulinic acid
Mean serum creatinine and uric acid higher in exposed
than controls (1.23 vs. 1.1 mg/dL; p < 0.05 and 6.6 vs.
4.7 mg/dL; p < 0.001, respectively).
Serum creatinine 31.5 mg/dL present in 32.7% Pb
workers compared to only 2.3% controls.
Serum creatinine correlated with duration of
employment.
Limitations = data analysis including lack of
adjustment, several outcomes not analyzed.
Australia
Pollock and Ibels
(1988)
Harbor Bridge
workers in Sydney,
Australia
Study date not
provided
38 bridge workers.
Twenty-four h urine Pb excretion following 1 g of EDTA.
Renal outcomes = serum creatinine, creatinine clearance,
and 24 h urine protein excretion.
Mean (range) blood Pb
34.8 (21.8 to 56.2) ug/dL (Pb
intoxication)
19.9 (9.5 to 26.1) ug/dL
(nontoxic)
EDTA chelatable Pb range
443 to 2366 ug/24 hrs (Pb
intoxication)
131 to 402 ug/24 hrs
(nontoxic)
No significant differences in renal outcomes by Pb
exposure group. Two workers in high exposure group
had evidence of Pb nephropathy.
-------
Table AX6-4.2 (cont'd). Renal Effects of Lead in the Occupational Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
Asia (cont'd)
Chiaetal. (1994b)
Study location not
provided; authors
from Singapore
1982-1992 (blood Pb
measurements
obtained every 6 mos
over this time)
Chiaetal. (1994c)
Singapore
Study location not
provided; authors
from Singapore
1982-1992 (blood Pb
measurements
obtained every 6 mos
over this time)
128 Pb workers.
152 control workers without Pb or cadmium exposure.
Renal outcomes = total NAG, NAG-B isoenzyme
(released with lysosomal breakdown assoc with cell
membranes, thought to indicate proximal tubular cell
toxicity), NAG-A (released by exocytosis).
Cross-sectional outcomes but longitudinal exposure data.
63 Pb workers of >6 mos work duration (median = 3 yrs).
91 Pb workers of <6 mos work duration were considered
controls.
Renal outcomes = urinary BB-50 (brush border antigen in
proximal tubule), total NAG, NAG-B isoenzyme, RBP, a-
1-microgobulin, albumin and urine and serum 32-
microglobulin.
Cross-sectional outcomes but longitudinal exposure data.
Median blood Pb
33.8 ug/dL (workers)
8.7 ug/dL (controls)
Median cumulative blood Pb
(mean of 3.6 blood Pb levels
per worker)
208.3 ug-yr/dL
Mean change in blood Pb
(in 6 mos preceding NAG
measurement)
5.8%
Pb dose measures
(means or medians not stated)
Most recent blood Pb, time
integrated blood Pb index,
relative % change in blood
Pb, absolute change in blood
Pb, number of times blood Pb
level >40, 50, and 60 ug/dL.
NAG not different in exposed compared to control
workers.
After adjustment for race, recent change in blood Pb
was significantly associated with all NAG outcomes
(standardized partial regression coefficients ranged
from 0.31 for NAG-A to 0.64 for total NAG; neither
SE nor CI provided).
In contrast, current blood Pb was inversely associated
with NAG-A and NAG-B separately but, oddly, not
with total NAG. Authors do not comment on these
inconsistencies.
NAG not associated with cumulative Pb dose.
Strengths = longitudinal exposure data.
Limitations = data analysis clarity and adjustment.
Urinary BB-50 higher in exposed compared to recent
hire "control" workers. Time integrated blood Pb,
number of times blood Pb >40 ug/dL, and relative
change in recent blood Pb were associated with
urinary BB-50.
Strengths = longitudinal exposure data.
Limitations = data analysis content (Pb dose means not
reported), clarity and adjustment.
-------
Table AX6-4.2 (cont'd). Renal Effects of Lead in the Occupational Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
Asia (cont'd)
Chiaetal. (1995a)
Study location not
provided; authors
from Singapore
1982-1993 (blood Pb
measurements
obtained every 6 mos
over this time)
Chiaetal. (1995b)
Study location not
provided; authors
from Singapore
1982-1993 (blood Pb
measurements
obtained every 6 mos
over this time)
137 Pb stabilizer workers.
Control group of 153 postal workers (older than Pb
workers).
Renal outcomes = serum creatinine, four h creatinine
clearance, serum 3-2 microglobulin, serum 40, 50,
and 60 ug/dL.
Mean recent blood Pb
32.6 ug/dL (workers)
9.0 ug/dL (controls)
Mean time integrated blood
Pb index
119.9 ug/dL Hyr (workers)
0.05 ug/dL H yr (controls)
Mean relative change in
recent blood Pb
28.2 % (workers)
Mean absolute change in
recent blood Pb
6.4 ug/dL/yr (workers)
Number of times blood Pb
level >40, 50 and 60 ug/dL
In analysis of covariance modeling, adjusted for age and race,
mean serum 30 yrs of age.
After adjustment for age, race, and smoking, prevalence rates
for abnormal values of serum creatinine and 3-2
microglobulin were higher in the highest category of time
integrated blood Pb index in workers 330 yrs of age
(PRR = 3.8[95%CI: 1.1, 13.3] and 10.3 [95% CI: 3.9,
26.9], respectively).
Strengths = longitudinal exposure data.
Limitations = data analysis content (Pb dose means not
reported), clarity and adjustment.
Only urinary a-1 microglobulin was significantly higher in Pb
workers compared to controls.
In multiple linear regression analysis, adjusted only for
ethnicity and smoking, at least one Pb measure was
significantly associated with each of the five renal outcomes.
Outcome
Ua-lMG
U a-1 MG
U 3-2 MG
URBP
S 3-2 MG
UAlb
Pb measure
cum. blood Pb
# blood Pb>50
cum. blood Pb
# blood Pb >50
# blood Pb >60
# blood Pb >60
3 (95% CI)
0.10(0.06,0.14)
0.43 (0.04, 0.82)
0.05(0.01,0.09)
0.35(0.12,0.59)
0.47(0.29,0.65)
0.66(0.13,1.19)
Cadmium dose measures reportedly not significant in these
models (although power would have been reduced as
cadmium measured only in a subset).
Strengths = longitudinal exposure data.
Limitations = data analysis clarity and adjustment. Overlap
in populations between this study and earlier ones possible.
-------
Table AX6-4.2 (cont'd). Renal Effects of Lead in the Occupational Population
X
to
Reference, Study
Location, and
Period
Asia (cont'd)
Endoetal. (1990)
Study location not
provided; authors
from Japan
1987
Study Description
39 male workers.
7 female workers (none directly exposed to Pb).
Secondary Pb refinery, mean job duration =10.5 yrs
Renal outcomes = BUN, serum creatinine and uric acid,
urinary NAG, and tubular reabsorption of phosphate.
Pb Measurement
Mean blood Pb
Ranged from 24. 1 to
67.6 ug/dL (males)
19.6 ug/dL (females)
Other Pb measures included
Findings, Interpretation
Significant correlations of blood Pb and delta-amino-levulinic
acid with BUN and NAG were observed. The correlation
between blood Pb and NAG was dependent on a small
number of workers whose blood Pb levels were above
80 ug/dL.
Endoetal. (1993)
Study location and
date not provided;
authors from Japan
99 male Pb workers.
Renal outcomes = serum creatinine and serum and urine
alpha-1 -microglobulin.
urinary Pb, delta-
aminolevulinic acid, and
coproporphyrin.
Median blood Pb
Ranged from 7.9 ug/dL in
category I consisting of 16
office workers who did not
work directly with Pb to
76.2 ug/dL in 16 workers in
the highest exposure group
(category V).
Limitations include absence of adjustment in statistical
analysis, small sample size.
Median urinary alpha-1-microglobulin significantly higher in
categories III-V compared to the low exposure group of
office workers. This was also the only renal outcome to be
significantly correlated with blood Pb (Spearman rank
correlation).
After alpha-1-microglobulin adjusted for age and blood Pb
(by stratifying); few significant differences noted. However,
analysis approach resulted in substantial loss of power.
-------
Table AX6-4.2 (cont'd). Renal Effects of Lead in the Occupational Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Hsiao etal. (2001)
Taiwan, PR China
1991-1998
X
30 Pb battery workers.
Mean serum creatinine at baseline
-1.0 mg/dL (based on figure; exact values not provided)
Longitudinal Analysis, 8 annual evaluations.
Generalized estimating equations used to adjust for
autocorrelation in multiple datapoints from each
participant.
Adjusted for age, gender, and, in models of change in
serum creatinine, creatinine at beginning of interval.
Mean blood Pb at baseline
—35 ug/dL (based on figure;
exact values not provided)
Mean duration of exposure
at baseline
13.1 vrs
Cross-sectional
higher blood Pb associated with lower concurrent
serum creatinine.
Longitudinal
Change in blood Pb negatively associated with
concurrent change in serum creatinine (p = 0.07).
Blood Pb at the beginning of the interval not associated
with change in serum creatinine in the following yr.
Associations may represent Pb-related hyperfiltration.
However, as noted by the authors, cumulative Pb dose
may also be a factor. Mean blood Pb declined greatly
just before renal data collection started. Therefore, the
inverse longitudinal associations could be due to
persistently elevated cumulative dose (which was
unmeasured but, as evidenced by the long half-life of
bone Pb, likely did not decline as much as blood Pb).
However, authors did not model cumulative blood Pb
or analyze effect modification by time period, age, or
exposure duration to determine if these associations
changed in a pattern consistent with hyperfiltration.
The small sample size also limits conclusions that may
be drawn from these results since a small number of
individuals may be overly influential.
Strengths = longitudinal data.
Limitations = data analysis content (Pb dose means not
reported), clarity and adjustment.
-------
Table AX6-4.2 (cont'd). Renal Effects of Lead in the Occupational Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
Asia (cont'd)
Huang etal. (1988)
Beijing, China
Study date not
provided
Jung etal. (1998)
Korea
Study date not
provided
Konishi, et al. (1994)
Study location
not provided;
research team from
Japan
1991
40 Pb workers (4 women).
Control group not described.
Renal outcomes = serum beta-2-microglobulin and urinary
beta-2-microglobulin, total protein, IgG.
75 randomly selected male Pb workers.
64 male office workers (controls).
Renal outcomes = BUN, serum creatinine, uric acid and
urinary NAG, albumin, a! microglobulin and 32
microglobulin.
99 male Pb workers, including 16 office workers to serve
at controls.
renal outcomes = fractional clearances of 0.1 microglobulin
and 32 microglobulin (utilizing serum and urinary levels of
both biomarkers), BUN, serum creatinine, uric acid and
urinary NAG.
Geometric mean blood Pb
40 ug/dL
Mean blood Pb
Means ranged from 24.3 to
74.6 ug/dL (workers)
7.9 ug/dL (controls)
Other Pb measures included
zinc protoporphyrin,
8-aminolevulinic acid activity
and urinary Pb,
coproporphyrin, and
8-aminolevulinic acid.
Median blood Pb
Range from 7.9 ug/dL in
controls to 76.2 ug/dL in
Category V
Increased urinary 32 microglobulin in workers
compared to controls.
Multiple limitations including lack of information on
control group, data analysis.
Blood Pb, zinc protoporphyrin, and urinary 8-
aminolevulinic acid significantly correlated with BUN,
NAG, and a! microglobulin (appears to be combined
group analysis).
Limitation = statistical analysis - lack of adjustment.
Urinary NAG, al microglobulin and fractional
clearance of 0.1 microglobulin increased with higher
blood Pb category. Spearman rank correlation between
fractional clearance of a! microglobulin and blood Pb
was significant. This relation also assessed by multiple
linear regression with adjustment for age; both
independent variables were significantly associated
with the fractional clearance of a! microglobulin.
Limitation = statistical analysis - lack of adjustment.
-------
Table AX6-4.2 (cont'd). Renal Effects of Lead in the Occupational Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
Asia (cont'd)
Kumar and
Krishnaswamy
(1995)
India
Study date not
provided
Limetal. (2001)
Singapore
1999
Blood Pb levels every
6 mos from 1982 to
1999
22 auto mechanics volunteers.
27 male control workers (from Institute performing study).
Renal outcomes = serum creatinine, 4 h creatinine
clearance and urinary NAG and 3-2 microglobulin.
Renal disease, diabetes, HTN and occupational exposures
excluded in controls, possibly excluded in workers.
55 male Pb workers.
Workers followed since 1982, many of same workers as in
Chiaetal. (1995b).
Renal outcomes = 4 h creatinine clearance and urinary
albumin, RBP, 0.1 microglobulin, 32 microglobulin, NAG,
NAG-A, andNAG-B.
Exclusionary criteria included diabetes, HTN, recent
ingestion of analgesics, antipyretics, or antibiotics, and
thalassemia; 24 participants of the original 80 were
excluded as a result. One female also excluded.
Blood Pb range
24.3-62.4 ug/dL (exposed)
19.4-30.6 ug/dL (controls)
Mean current blood Pb
24.1 ug/dL
Cumulative blood index
880.6 ug H yrs/dL (geometric
mean)
Number of times blood Pb
exceeded 40 ug/dL
1.9 (geometric mean)
Urinary NAG and 32 microglobulin levels were
significantly higher in exposed compared to controls.
However, only NAG was significantly correlated with
blood Pb (r=0.58, p< 0.01).
Limitations = study size and lack of adjustment in
analysis, values for 4 h creatinine clearance in
abnormal low range in both exposed and controls.
In separate models, after adjustment for age and
smoking, higher categorical cumulative blood index
and number of times blood Pb exceeded 40 ug/dL were
associated with lower creatinine clearance (P < 0.001).
After adjustment, higher number of times blood Pb
exceeded 40 ug/dL was associated with higher urinary
albumin, a! microglobulin, RBP, NAG, and NAG-B.
Similarly, cumulative blood index was associated with
higher urinary albumin, a! microglobulin, RBP, and 32
microglobulin.
No associations between recent blood Pb and any of
the renal outcomes was observed.
Analysis of covariance was used to adjust for smoking
and age.
Limitation = statistical analysis - lack of adjustment,
small sample size, potential for healthy worker bias.
-------
Table AX6-4.2 (cont'd). Renal Effects of Lead in the Occupational Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
Oi
OD
Oi
Asia (cont'd)
Ongetal. (1987)
Singapore and Japan
Study date not
provided
Wang et al. (2002b)
Taiwan
Study date not
provided
209 Pb workers (51 females).
30 control workers from research staff.
Renal outcomes = BUN, serum creatinine, calculated
creatinine clearance, and urinary NAG.
229 Pb battery workers, including 109 females.
Renal outcomes = BUN, serum creatinine, serum
uric acid.
Multiple linear & logistic regression.
Adjustment for age, gender, smoking, alcohol ingestion,
milk ingestion.
Mean blood Pb
42.1 ug/dL (males)
31.9 ug/dL (females)
Urine Pb also measured.
Mean blood Pb
67.7 ug/dL (males)
48.6 ug/dL (females)
Blood Pb correlated with BUN(r = 0.16; p < 0.01),
serum creatinine (r = 0.26; p < 0.001) and creatinine
clearance (r = -0.16; p < 0.01). Blood Pb associated
with NAG after adjustment for age (method not
specified).
Higher NAG in exposed compared to controls when
stratified by categorical age.
Strengths = sample size.
Limitations = statistical analysis - lack of adjustment,
urinary NAG not adjusted for urine dilution.
3 (95% CI) for blood Pb in model of BUN, after
adjustment for Pb job duration/age = 0.062
(0.042, 0.082).
3 (95% CI) for blood Pb in model of uric acid, after
adjustment for gender and weight = 0.009
(0.001,0.016).
Blood Pb not associated serum creatinine.
-------
Table AX6-4.2 (cont'd). Renal Effects of Lead in the Occupational Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Weaver et al. (2003a)
South Korea
1997-1999
X
803 Pb workers including 164 females and 94 former Pb
workers.
Serum creatinine
0.90 mg/dL
Calculated creatinine clearance
94.7 mL/min
4-hr measured creatinine clearance
114.7 mL/min
RBP
63.6 jig/g creatinine
NAG
215.3 |j,mol/h/g creatinine
Multiple linear regression, adjusting for age, gender, BMI,
work status (current vs. former worker), HTN or blood
pressure (depending on model), and, for the EBE markers,
alcohol ingestion and diabetes.
42 associations modeled (7 Pb measures with 6 renal
outcomes).
Interaction models that assessed effect modification by
age in tertiles in 24 associations (4 Pb exposure/dose
measures with 6 renal outcomes).
Mean blood Pb
32.0 ng/dL
Mean tibia Pb
37.2 (ig/g bone mineral
Mean DMSA-chelatable Pb
767.8 (ig/g creatinine
Pb exposure also assessed
with job duration and three
hematologic measures as
surrogates for Pb dose
(aminolevulinic acid in
plasma, zinc protoporphyrin,
and hemoglobin).
Mean urinary cadmium
measured in
subset (n= 191)
1.1 ng/g creatinine
After adjustment, higher Pb measures associated with
worse renal function in 9 of 42 models.
Associations in the opposite direction (higher Pb
measures associated with lower serum creatinine and
higher creatinine clearances) in five models.
Opposite direction (inverse) associations observed only
in models of the clinical outcomes whereas the
associations between higher Pb dose and worse renal
function were predominantly among the biomarker
models.
In three of 16 clinical renal interaction models, positive
associations between higher Pb measures and worse
renal function in participants in the oldest age tertile
were significantly different from associations in those
in the youngest age tertile which were in the opposite
direction.
- This pattern was observed at borderline significance
(p<0.l)m3 other models.
- Pattern was not observed in the EBE marker models.
Urinary cadmium associated with NAG.
Authors concluded that occupational Pb exposure in
the moderate dose range has an adverse effect on renal
function. Inverse associations may represent
hyperfiltration. Environmental cadmium may have an
adverse impact, at least on NAG.
-------
Table AX6-4.2 (cont'd). Renal Effects of Lead in the Occupational Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Weaver et al. (2003b) 798 Pb workers with genotype information in same
Korea Pb workers
1997-1999
population as in Weaver et al. (2003a).
79 (9.9%) participants were heterozygous for the ALAD2
allele (none was homozygous).
89 (11.2%) had VDR genotype Bb or BB.
X
oo
Mean blood Pb
31.7ng/dL(ALADll)
34.2 ng/dL (ALAD12)
31.6ng/dL(VDRbb)
34.8 ng/dL (VDR Bb or BB)
Mean tibia Pb
37.5 |ig/g(ALADI 1)
31.4ng/g(ALAD12)
37.1 |ig/g(VDRbb)
38.1 |ig/g (VDR Bb or BB)
Data were analyzed to determine whether
polymorphisms in the genes encoding 8-aminolevulinic
acid dehydratase (ALAD), endothelial nitric oxide
synthase (eNOS), and the vitamin D receptor (VDR)
were associated with renal outcomes or modified
relations of Pb exposure and dose measures with renal
outcomes.
After adjustment, participants with the ALAD2 allele
had lower mean serum creatinine and higher calculated
creatinine clearance. Effect modification by ALAD on
associations between blood Pb and/or DMSA-
chelatable Pb and three of six renal outcomes was
observed. Among those with the ALAD 12 genotype,
higher Pb measures were associated with lower BUN
and serum creatinine and higher calculated creatinine
clearance.
No significant differences were seen in renal outcomes
by VDR genotype nor was consistent effect
modification observed.
-------
Table AX6-4.2 (cont'd). Renal Effects of Lead in the Occupational Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Mean blood Pb
32.0
Asia (cont'd)
Weaver et al. (2005a) 803 current and former Pb workers; 164 females.
Korea
1997-1999 Serum Uric acid
4.8 mg/dL Mean tibia Pb
37.2 (40.4) ng/g bone
Other renal outcomes as listed in Weaver et al., 2003a. mineral
Multiple linear regression. Mean DMSA-
chelatable Pb
Interaction models that assessed effect modification by age 767.8 ng/g creatinine
in tertiles.
X
Work to address whether one mechanism for Pb-related
nephrotoxicity, even at current lower levels of Pb exposure, is via
increasing serum uric acid. Assessed 1) whether Pb dose was
associated with uric acid and 2) whether previously reported
associations between Pb dose and renal outcomes (Weaver et al.,
2003) were altered after adjustment for uric acid.
After adjustment for age, gender, body mass index, and alcohol use,
Pb biomarkers not associated with uric acid in all participants.
However, in interaction models, both blood and tibia Pb were
significantly associated in participants in the oldest age tertile
(3 = 0.0111 [95% CI: 0.003, 0.019] and 0.0036 [0.0001, 0.007] for
blood and tibia Pb, respectively). These models were further adjusted
for blood pressure and renal function. Hypertension and renal
dysfunction are known to increase uric acid. However, they are also
risks associated with Pb exposure. Therefore, adjustment for these
variables in models of associations between Pb dose and uric acid
likely results in over-control. On the other hand, since nonPb related
factors contribute to both renal dysfunction and elevated blood
pressure, lack of adjustment likely results in residual confounding.
Therefore, as expected, associations between Pb dose and uric acid
decreased after adjustment for systolic blood pressure and serum
creatinine, although blood Pb remained borderline significantly
associated (3 = 0.0071 [95% CI: !0.001, 0.015]). However, when the
population was restricted to the oldest tertile of workers with serum
creatinine greater than the median (0.86 mg/dL), likely the highest
risk segment of the population, blood Pb remained significantly
associated with uric acid even after adjustment for systolic blood
pressure and serum creatinine (3 = 0.0156).
Next, in models of renal function in all workers, uric acid was
significantly (p < 0.05) associated with all renal outcomes except
NAG.
In models in the oldest tertile of workers (266 workers, median age
51.1 yrs, range 46.0 to 64.8 yrs), after adjustment for uric acid,
associations between Pb dose and NAG were unchanged, but fewer
of the previously significant (p # 0.05) associations noted between Pb
dose and the clinical renal outcomes in Weaver et al. (2003a)
remained significant.
-------
Table AX6-4.2 (cont'd). Renal Effects of Lead in the Occupational Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Weaver et al. (2005b)
South Korea
1999-2001
X
O
O
652 Pb workers including 149 females and 200 former
workers.
Patella Pb measured in the third evaluation of the same
study reported in Weaver et al. (2003a). Data collection
performed a mean of 2.2 yrs after collection of the data
presented in Weaver et al. (2003a).
Same renal outcomes as Weaver et al. (2003a).
Serum creatinine
0.87 mg/dL
Calculated creatinine clearance
97.0 mL/min
Multiple linear regression, adjusting for age, gender, BMI,
work status (current vs. former worker), HTN or blood
pressure (depending on model), diabetes, smoking status,
and, for the clinical measures, use of analgesics
Interaction models assessed effect modification by age,
dichotomized at the 67th percentile.
Mean blood Pb
30.9 ug/dL
Mean tibia Pb
33.6 ug/g bone mineral
Mean patella Pb
75.1 ug/g bone mineral
Mean DMSA-chelatable Pb
0.63 (ig Pb/mg creatinine
All 4 Pb measures were correlated (Spearman's r = 0.51 -
0.76).
Patella, blood and DMSA-chelatable Pb levels positively
associated with NAG.
Higher DMSA-chelatable Pb associated with lower serum
creatinine and higher calculated creatinine clearance.
Interaction models
All four Pb measures associated with higher NAG among
participants in oldest age tertile.
Higher blood, tibia, and patella Pb associated with higher
serum creatinine among older participants.
-Beta coefficients less in the Pb workers whose ages were in
the younger two-thirds of the age range; difference between
slopes in the two age groups was statistically significant only
for association of blood Pb and serum creatinine.
Inverse DMSA associations (higher DMSA-chelatable Pb
associated with lower serum creatinine and higher calculated
creatinine clearance) significant in younger workers.
Patella Pb associations were consistent with those of blood and
tibia Pb; DMSA-chelatable Pb associations unique.
Authors hypothesized that similarities between patella, blood,
and tibia Pb associations could be due, in part, to high
correlations among the Pb biomarkers in this population.
Despite similar high correlations, DMSA-chelatable Pb
associations with serum creatinine and calculated creatinine
clearance were unique. This biomarker is dependent on renal
function and the collection time was only 4 h. Therefore, the
amount of Pb that is excreted in this relatively short time period
after chelation may be influenced not only by bioavailable Pb
burden, but also by high-normal as well as actual supranormal
glomerular filtration which are more common in the younger
workers.
-------
Table AX6-4.2 (cont'd). Renal Effects of Lead in the Occupational Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Weaver et al. (2005c)
Korea
1997-1999
798 current and former Pb workers.
Same population as in Weaver et al. (2003a,b).
X
Ye et al. (2003)
Chinese Pb workers
Study date not
provided
216 Pb workers.
Renal outcomes = urinary NAG and albumin.
Geometric mean blood Pb
37.8 ng/dL (n = 14 workers
with the ALAD12 genotype)
32.4 |ig/dL (n = 212 workers
with the ALAD11 genotype)
31.9ug/dL(VDRbb)
41.7 ug/dL (in 20 participants
withVDRBborBB)
Data were analyzed to determine whether
polymorphisms in the genes encoding 8-aminolevulinic
acid dehydratase (ALAD), endothelial nitric oxide
synthase (eNOS), and the vitamin D receptor (VDR)
were associated with uric acid or modified relations of
Pb exposure and dose measures with uric acid.
Uric acid not different by ALAD or VDR genotype.
Among older workers (age > median of 40.6 yrs),
ALAD genotype modified associations between Pb
dose and uric acid levels. Higher Pb dose was
significantly associated with higher uric acid in
workers with the ALAD11 genotype; associations were
in the opposite direction in participants with the variant
ALAD 12 genotype.
After adjustment for age, NAG was borderline higher
in those with the ALAD variant allele whose blood Pb
levels were >40 jag/dL (p = 0.06). In all Pb workers,
after adjustment for age, gender, smoking, and alcohol
ingestion, a statistically significant positive association
between blood Pb and creatinine adjusted NAG was
observed in the workers with the ALAD 12 genotype
but not in Pb workers with the ALAD11 genotype (the
groups were analyzed separately rather than in an
interaction model).
No effect modification by VDR genotype on
associations between blood Pb and urinary albumin
and NAG observed (separate analysis reduced power).
-------
Table AX6-4.2 (cont'd). Renal Effects of Lead in the Occupational Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Middle East
Al-Neamy et al.
(2001)
United Arab Emirates
Feb-June, 1999
100 "industrial" workers exposed in a range of industries
100 working controls.
Matched for age, sex, and nationality.
Renal outcomes = BUN, serum creatinine.
Mean blood Pb
77.5 ug/dL (workers)
19.8 ug/dL (controls)
Mean BUN and serum creatinine not statistically
different between exposed workers and controls.
Limitations = data analysis.
X
O
to
Ehrlichetal. (1998)
South Africa
Study date not
provided
382 Pb battery factory workers.
Mean age = 41.2yrs.
All males.
Multiple linear regression adjusted for age, weight, and
height (Covariates assessed for inclusion also included
smoking, alcohol ingestion, and diabetes).
Clinical renal outcomes included serum creatinine, uric
acid, and BUN.
Mean serum creatinine
1.13mg/dL
Renal early biological effect markers (NAG, RBP,
intestinal alkaline phosphatase, tissue nonspecific alkaline
phosphatase, Tamm-Horsfall glycoprotein, epidermal
growth factor, and microalbuminuria) were measured in
199 participants randomly selected by tertiles of current
blood Pb.
Mean blood Pb
53.5 ug/dL
Mean exposure duration
11.6 yrs
Mean cumulative blood Pb
(defined as sum of the avg
blood Pb in each yr over all yrs
of employment; done in subset
of 246 with past blood Pb data)
579.0 (ugHyr)/dL
Mean historical blood Pb
(defined as cumulative blood
Pb divided by yrs of exposure)
57.3 ug/dL
Mean tibia Pb
69.7 (ig/g bone mineral
(measured 2 yrs after initial
study on random sample of 40)
After adjustment for age, weight, and height,
categorical current and historical blood Pb and zinc
protoporphyrin were associated with serum creatinine
and uric acid, in separate models. Associations
between cumulative blood Pb or exposure duration
and the renal outcomes were not observed.
Among the EBE markers, only current blood Pb was
borderline associated with NAG (p = 0.09).
Associations with renal dysfunction were observed at
blood Pb levels <40 (ig/dL. Not explained by an
effect on blood pressure since Pb measures not
associated with blood pressure. Blood cadmium
measured in 56 participants 2 yrs after the initial
study. All low (#1.2 (ig/L) suggesting that
occupational level cadmium exposure was not a
contributing factor. The authors did implicate Pb
body burden, which was substantial based on mean
tibia Pb. However, cumulative blood Pb was not
associated in this study and mean tibia Pb in Roels
et al. (1994) was similar (in that study a positive
association with creatinine clearance was observed).
-------
Table AX6-4.2 (cont'd). Renal Effects of Lead in the Occupational Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
Middle East (cont'd)
El-Safty et al. (2004)
Egypt
Study date not
provided
Mortadaetal. (2001)
Egypt
Study date not
provided
45 Pb workers with Pb job duration <20 yrs.
36 Pb workers with Pb job duration >20 yrs.
75 control workers.
Renal outcomes = urinary armicroglobulin, NAG, and
glutathione S-transferase.
43 traffic policemen.
52 matched control office workers (similar in terms of
age, gender, smoking, and "social life").
Renal outcomes = serum creatinine, beta-2 microglobulin,
BUN and urinary 3-2- microglobulin, NAG, alkaline
phosphatase, y-glutamyl transferase, and albumin.
Exclusionary criteria included diabetes, HTN, hepatic,
renal or urologic diseases.
Median urine Pb
Ranged from 15.4 ug/g
creatinine in nonsmoking
control workers to 250.4 ug/g
creatinine in smoking Pb
workers with 320 yrs Pb job
duration.
Mean blood Pb
32.1 ug/dL (exposed)
12.4 ug/dL (controls)
Pb also measured in hair, urine
and nails.
Medians of all 3 renal outcomes significantly higher
in Pb workers regardless of smoking status (analysis
stratified by smoking status).
Urine Pb significantly correlated with urinary ar
microglobulin and glutathione S-transferase in
nonsmoking Pb workers and with NAG as well in
smoking Pb workers.
Limitations include using urine Pb as sole Pb dose
measure and data analysis.
NAG and albumin significantly higher in policemen
compared to controls. NAG positively correlated
(Pearson's) with job duration and blood and nail Pb.
Urinary albumin positively correlated with job
duration and blood and hair Pb.
Limitations: data analysis - no adjustment, use of
parametric correlation techniques with data likely to
be nonparametric; study size.
-------
Table AX6-4.3. Renal Effects of Lead in the Patient Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
United States
Osterlohetal. (1989)
Northern CA
Study date not
provided
40 male subjects with hypertensive nephropathy
(hypertension preceded renal insufficiency; serum
creatinine 1.8-4 mg/dL).
24 controls with renal dysfunction from other causes.
Patients recruited from the Kaiser Permanente Regional
Laboratory database (large health maintenance
organization) in northern California.
Mean blood Pb
7.3 ug/dL (in both
hypertensive nephropathy and
controls CRI from other
causes)
Mean EDTA chelatable Pb
levels
153.3 ug/72 hrs (hypertensive
nephropathy)
126.4 ug/72 hrs (control CRI)
Steenlandetal. (1990)
Michigan
Diagnosis from
1976-1984
325 men with ESRD (diabetes, congenital and obstructive
nephropathies excluded).
Controls by random digit dialing, matched by age, race,
and place of residence.
No significant difference in EDTA chelatable Pb
levels; highest chelatable Pb level was
609.2 ug/72 hrs.
Pb dose and serum creatinine were not correlated.
Blood and chelatable Pb levels much lower than those
reported by Wedeen et al. (1983) and
Sanchez-Fructuoso et al. (1996).
Only 17% of their study participants had a history of
possible Pb exposure based on questionnaire, again
much lower than the two other studies.
Risk of ESRD significantly related to moonshine
alcohol consumption (OR = 2.43), as well as
analgesic consumption, family history of renal
disease, and occupational exposure to silica or
solvents.
Europe
Behringer et al.
(1986)
Germany
Study date not
provided
16 patients with CRI (median serum creatinine =
2.2 mg/dL) and gout.
19 patients with CRI (median serum creatinine =
5.1 mg/dL) without gout.
21 healthy controls.
Pb excretion in the 96 hrs after administration of 1
EDTA iv.
Median blood Pb
7.2 ug/dL (controls)
11.5 ug/dL (CRI, no gout)
15.3 ug/dL (CRI & gout)
Median EDTA chelatable Pb
(ug/4 days/1.73m2)
63.4 (controls)
175.9 (CRI, no gout)
261.3 (CRI & gout)
EDTA chelatable Pb higher in gout patients who
developed gout after CRI than those in which gout
preceded CRI (statistical test results not mentioned or
shown). Authors conclude a role for Pb in patients
with gout occurring in setting of CRI and that Pb may
contributes to renal function decline in established
renal disease from other causes.
Limitations = small groups, limited data analysis.
-------
Table AX6-4.3 (cont'd). Renal Effects of Lead in the Patient Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
Europe (cont'd)
Colleoni and
D'Amico (1986)
Italy
(-1982-1985)
Colleoni et al. (1993)
Italy
Study date not
provided
Craswell et al. (1987)
Germany and
Australia
Study date not
provided
12 consecutive patients with CRI (mean serum
creatinine = 3.3 mg/dL) and gout, renal diagnosis
consistent with chronic interstitial nephritis in all; 7 had
history of occupational Pb exposure.
12 controls with chronic glomerulonephritis and no
history of Pb exposure or gout.
Pb excretion in the 48 hrs after administration of 1.5 g
EDTA im.
All 115 patients on hemodialysis at the time of the study;
41 women.
Blood Pb data from prior study of 383 healthy controls in
same geographical area served as comparison.
Mean EDTA chelatable Pb
(ug/48 hrs)
180 (CRI, no gout)
505 (CRI & gout)
Mean blood Pb
(corrected for hemoglobin)
19.9 ug/dL (patients)
14.7 ug/dL (controls)
See discussion below under Australia.
Significantly higher EDTA chelatable Pb in the
group with CRI and gout compared to CRI alone.
EDTA chelatable Pb significantly correlated with
serum creatinine in patients with CRI and gout but
not CRI alone. Authors conclude that Pb is cause of
CRI with gout but renal insufficiency alone not
responsible for increased Pb body burden (absence
of evidence for reverse causation).
Limitations = small sample size, limited data
analysis.
Significantly higher mean blood Pb in hemodialysis
patients compared to healthy controls. 13% had
blood Pb levels >30 ug/dL. Blood Pb level was not
associated with duration of hemodialysis. Mean Pb
levels higher in smokers and in relation to alcohol
ingestion. Pb not detectable in dialysis fluids.
Limited data analysis.
-------
Table AX6-4.3 (cont'd). Renal Effects of Lead in the Patient Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
Oi
O
Oi
Europe (cont'd)
Fontanellas et al.
(2002)
Spain
Study date not
provided
Jones etal. (1990)
Study location and
date not provided;
authors from UK
Kosteretal. (1989)
Study location and
date not provided;
authors from
Germany
ALAD/restored ALAD as a possible index of Pb poisoning
in chronic renal failure patients.
27 dialysis patients.
59 healthy controls.
91 patients with CRI (median serum creatinine :
2.5 mg/dL).
46 age-matched normal controls.
Pb excretion in the 4 days after
1 g EDTA iv.
Mean blood Pb
8.1 ug/dL (patients)
10.0 ug/dL (controls)
Mean blood Pb
(corrected for hemoglobin)
11.2 ug/dL (patients)
7.6 ug/dL (controls)
Mean EDTA chelatable Pb
164.7 ug/4 days II .73m2
(patients)
63.6 ug/4 days II.73m2
(controls)
Restored ALAD was measured after the addition of
zinc and dithiothreitol (DTT) to the incubation
media.
The ALAD/restored ALAD ratio was found to
correlate with the results of the EDTA Pb
mobilization test. Patients excreting 1,115 to
3860 ug Pb per 72 hrs had a ratio of 0.19 while
chronic renal failure patients excreting an avg of
322 ug Pb (range 195 to 393) had a ratio of 0.47.
In comparison, normal controls had a ratio of 0.5.
Tibia Pb levels not correlated with blood Pb but were
correlated with Pb in bone biopsy measurements
(r = 0.42).
Limitations = data analysis.
CRI patients had significantly higher blood and
EDTA chelatable Pb levels than controls. In 13% of
the CRI patients, EDTA chelatable Pb exceeded the
highest value in controls (328.8 ug). EDTA
chelatable Pb levels were correlated with serum
creatinine in patients (r = 0.37; p < 0.007).
Limitations = data analysis.
-------
Table AX6-4.3 (cont'd). Renal Effects of Lead in the Patient Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
Europe (cont'd)
Miranda-Canis et al.
(1997)
Spain
1990-1994
Nuytsetal. (1995)
Belgium
Study date not
provided
27 patients with gout and CRI.
50 patients with gout only.
26 controls with normal renal function and no gout.
Multiple purine metabolism measures including serum
urate, hypoxanthine, and xanthine, as well as their
excretion, clearance and fractional excretion measures.
Mean blood Pb
17.8 ug/dL (gout and CRI)
14.9 ug/dL (gout only)
12.4 ug/dL (controls)
Mean EDTA chelatable Pb
845 ug/120 hrs (gout and CRI)
342 ug/120 hrs (gout only)
215 ug/120 hrs (controls)
Case-control study.
272 cases with chronic renal failure (all types) matched to
272 controls by age, sex and residence.
Exposure assessed by 3 industrial hygienists blinded to
case or control status.
Pb dose measures significantly higher in patients with
gout and CRI compared to the other two groups.
EDTA chelatable Pb inversely correlated with
creatinine clearance. Each of the 2 patient groups
were dichotomized by EDTA-chelatable Pb level of
600 |j,g/120 hrs, resulting in 3 small groups (n ranging
from 6 to 14) and one group of 44 participants with
gout and EDTA chelatable Pb below the cut-off. No
significant differences in mean purine metabolism
measures were observed. It is not clear whether
correlations between EDTA-chelatable Pb and the
purine measures were assessed and if so whether the
small groups were combined for this analysis. Thus
lack of power may be one reason for the inconsistency
with Lin's work. Different Pb body burdens may be a
factor as well.
Uric acid parameters were unchanged following
chelation in 6 participants with EDTA-chelatable
above 600 ug/120 hrs. Again higher Pb body burdens
may be a factor but the small number and limited
details on the group make firm conclusions difficult.
Significantly increased odds ratio for chronic renal
failure with Pb exposure (OR = 2.11 [95% CI: 1.23,
4.36]) as well as several other metals. Increased risk
with diabetic nephropathy.
-------
Table AX6-4.3 (cont'd). Renal Effects of Lead in the Patient Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Sanchez-Fructuoso
etal. (1996)
Spain
Study date not
provided
296 patients:
Group I = 30 normal control subjects
Group II = 104 patients with essential HTN & normal
renal function
Group III-A = 68 patients with HTN and CRI of uncertain
etiology but presumed nephroangiosclerosis
Group III-B = 64 patients with HTN, CRI, and gout
Group IV = 30 patients with CRI of known etiology
X
O
oo
Mean blood and EDTA-
chelatable Pb levels
Group I
16.7 ug/dL
324 ug/72 hrs
Group II
16.8 ug/dL
487 ug/72 hrs
Group III-A
18.5 ug/dL
678 ug/72 hrs
Group III-B
21.1 ug/dL
1290 ug/72 hrs
Group IV
16.5 ug/dL
321 ug/72 hrs
EDTA chelatable Pb >600 ug/72 hrs in 16 patients in
group II, 30 patients in group III-A, 44 patients in
group III-B, but no patients in either group I and IV.
Mean blood and EDTA chelatable Pb levels in the
patients with CRI of known cause were not
statistically different from controls with normal renal
function. However, baseline urinary Pb excretion was
lower in group IV. This provides conflicting evidence
regarding the "reverse causality" hypothesis of
increased Pb burden due to decreased excretion in
CRI.
Significant correlations noted between bone Pb levels
(assessed by biopsy) and EDTA chelatable Pb level in
12 patients whose chelatable Pb levels were >600
ug/72 hrs; provides support for validity of chelatable
Pb levels in CRI.
A positive correlation was observed between serum
creatinine levels and EDTA-chelatable Pb levels
>600 ug/72 hrs but not below this level.
In group III, mean measured creatinine clearance was
significantly lower in those with EDTA chelatable Pb
levels >600 l-ig/72 hrs compared to participants with
chelatable Pb <600 jag/72 hrs.
-------
Table AX6-4.3 (cont'd). Renal Effects of Lead in the Patient Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
O
VO
Europe (cont'd)
Van de Vyver et al.
(1988)
Belgium, France
and Germany
Study date not
provided
Winterberg et al.
(1991)
Study location and
date not provided;
authors from
Germany
Transiliac bone biopsies obtained from:
11 cadavers without known Pb exposure and with normal
renal function
13 patients with CRI, gout and/or HTN 22 Pb workers
153 dialysis patients
Iliac crest bone Pb measured by biopsy in:
8 controls
8 patients with CRI
14 dialysis patients
Mean transiliac Pb levels
5.5 ug/g (153 dialysis pts)
20.6 ug/g (in highest 5%
dialysis pts)
3.7 ug/g (in 10 pts on dialysis
due to analgesic nephropathy)
6.3 ug/g (11 cadavers)
30.1 ug/g (22 Pb workers)
Mean iliac crest bone Pb levels
1.63 ug/g (8 controls)
2.18 ug/g (8 patients with
CRI)
3.59 ug/g (in 14 dialysis pts)
In 5% of the hemodialysis patients studied, bone Pb
concentrations approximated the levels found in
active Pb workers, suggesting Pb as a primary cause
of their renal failure. Levels in the 10 patients with
analgesic nephropathy were the lowest (all <7 ug/g),
evidence against reverse causality.
In the combined group of 13 patients with CRI, gout
and/or HTN and 22 Pb workers, EDTA chelatable Pb
correlated with Pb in bone biopsies (r = 0.87).
Noted that the bone Pb levels in patients with
analgesic nephropathy and cadaver controls in Van de
Vyver et al. (1988) were much higher than in control
groups of other researchers. They reiterated the
concern that Pb did accumulate due to decreased renal
excretion.
Latin and South America
Navarroetal. (1992)
Venezuela
Study date not
provided
18 dialysis patients.
14 controls.
Bone (biopsy) and blood levels of Pb and several other
metals.
Mean blood Pb
5.2 ug/dL (patients)
11.5 ug/dL (controls)
Mean Pb in bone
9.7 ug/g (patients)
7.0 ug/g (controls)
Blood but not bone Pb significantly higher in patients
compared to controls. Authors concluded that bone
accumulation of aluminum, iron and vanadium, but
not Pb, occurred in dialysis patients.
Limitations = sample size, data analysis including
lack of adjustment.
-------
Table AX6-4.3 (cont'd). Renal Effects of Lead in the Patient Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Australia
Craswelletal. (1987)
Germany and
Australia
Study date not
provided
X
German participants from industrialized area where
chronic Pb nephropathy not previously observed.
Gp 1=8 healthy controls (from hospital staff)
Gp 2a = 12 CRI patients, no gout or Pb exposure
Gp 2b = 7 CRI patients, no gout but + Pb exposure
Gp 3a = 7 CRI patients with gout but no Pb exposure
Gp 3b = 6 CRI patients with gout and Pb exposure
Australian participants from Queensland site of known
chronic Pb nephropathy.
Gp 1 = 9 healthy controls (from hospital staff)
Gp 2a = 14 CRI patients, no gout or Pb exposure
Gp 2b = 11 CRI patients, no gout but + Pb exposure
Gp 3a = 25 CRI patients with gout but no Pb exposure
Gp 3b = 11 CRI patients with gout and Pb exposure
CRI defined as serum creatinine > 1.5 mg/dL
"Excess" EDTA chelatable Pb defined as Pb excreted over
4 days after EDTA minus twice baseline Pb excreted pre-
EDTA.
Median blood Pb (hemoglobin
corrected)
Gpl
German =6.8 ug/dL
Australian = 11.0 ug/dL
Gp2a
German =6.2 ug/dL
Australian = 9.1 ug/dL
Gp2b
German =8.5 ug/dL
Australian = 16.2 ug/dL
German = 10.6 ug/dL
Australian = 12.8 ug/dL
Gp3b
German = 12.0 ug/dL
Australian = 27.1 ug/dL
Median "excess" EDTA
chelatable Pb
Gpl
German = 68.4 ug
Australian =82.9 ug
Gp2a
German = 126.4 ug
Australian = 393.7 ug
Gp2b
German = 489.0 ug
Australian = 1181.1 ug
German = 227.9 ug
Australian = 808.1 ug
Gp3b
German = 422.7 ug
Australian = 1077.5 ug
Using nonparametric statistical techniques due to
skewed data, German participants excreted
statistically less Pb than their Australian counterparts.
Mean EDTA chelatable Pb levels were significantly
higher in German patients with gout than in those
without gout; the observed increase in the Australian
patients was of borderline significance (p < 0.1).
Limitations = small groups, limited data analysis.
-------
Table AX6-4.3 (cont'd). Renal Effects of Lead in the Patient Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Australia (cont'd)
Price etal. (1992)
Queensland,
Australia
1981-1986
8 renal patients compared with age-matched controls.
X-ray fluorescence of finger bone Pb conducted twice 5
yrs apart.
Authors conclude that Pb in bone half-life is similar in
renal patients compared to age-matched controls.
Study limitations substantial, however.
Limitations = small numbers (although bone Pb
measured in more patients, many were below the limit
of detection, inclusion of outliers without formal
statistical analysis.
Asia
^ Lin and Lim (1992)
ON Chinese population
^ (likely in Taiwan)
i—> Study date not
provided
Lin and Huang
(1994)
Taiwan
Study date not
provided
10 healthy controls.
10 patients with CRI but no gout.
8 patients with gout and subsequent CRI.
6 patients with CRI and subsequent gout.
Exclusionary criteria included + history of occupational or
environmental Pb exposure.
Group 1 = 10 patients with normal renal function and no
gout; Group 2=10 patients with CRI (serum creatinine
>1.4 mg/dL) and subsequent gout; Group 3 = 20 patients
with CRI but no gout.
All males.
Pb body burden assessed with 1 g EDTA iv followed by
72 hr urine collection.
Mean EDTA chelatable Pb in
ug/72hrs/1.73m2
90.2 (controls)
98 (CRI, no gout)
171.6 (gout, then CRI)
359.8 (CRI, then gout)
Mean EDTA chelatable Pb
Gp 1 = 60.55 ug/72 hrs
Gp 2 = 252.24 ug/ 72 hrs
Gp3 = 84.86ug/72hrs
Pb body burden higher in patients with CRI and gout,
especially when CRI precedes gout.
Limitations = small sample sizes, statistical analysis.
Mean EDTA chelatable Pb and serum urate
significantly higher in the patients with gout. After
adjustment for creatinine clearance, log transformed
EDTA chelatable Pb was significantly associated with
serum urate levels (3 = 0.757 [95% CI: 0.142, 1.372];
p < 0.05), daily urate excretion (3 = 160.15 [95% CI:
1118.1, !2.16]; p< 0.05), urate clearance (3= 10.811
[95% CI: 11.34, !0.282]; p < 0.05), and fractional
urate excretion (3 = !1.535 [95% CI: !2.723, !0.347];
p < 0.05). EDTA chelatable Pb not associated with
creatinine clearance.
Limitations = small sample sizes, limited adjustment
in regression analyses.
-------
Table AX6-4.3 (cont'd). Renal Effects of Lead in the Patient Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
Asia (cont'd)
Lin and Lim (1994)
Taiwan
Study date not
provided
Lin etal. (1999)
Taiwan
Study date not
provided
Gp 1 = 12 healthy controls.
Gp 2 = 10 patients with HTN.
Gp 3 = 12 patients with HTN, then CRI (hypertensive
nephropathy).
Gp 4 = 12 patients with CRI only.
Gp 5 = 12 patients with CRI not due to HTN, but
subsequent HTN.
32 patients selected from 102 patients with serum
creatinine from 1.5-4.0 mg/dL who were followed in the
Institution's outpatient clinics.
Eligibility criteria included serum creatinine from 1.5 -
4.0 mg/dL, stable renal function over 6 mos before study
entry; controlled blood pressure and cholesterol; daily
protein intake <1 g/kg body wt; no known history of
exposure to Pb or other heavy metals and EDTA
chelatable Pb >150 but <600 jag/72 h.
Exclusionary criteria included potentially reversible or
unstable renal disease (i.e., due to systemic diseases such
as lupus and diabetes), and nephrotoxicant medications.
Patients divided into 16 patients receiving 1 g EDTA i.v.
weekly for two mos and a control group of 16 patients
who received no therapy.
Mean EDTA chelatable Pb
Gp 1 = 76.6 ug/72 hrs
Gp 2 = 67.96 ug/72 hrs
Gp3= 182.9 ug/72 hrs
Gp 3 = 84.46 ug/72 hrs
Gp 3 = 92.86 ug/72 hrs
Mean EDTA chelatable Pb
levels pre-chelation
254.9 Ug/72 hrs in group
receiving subsequent chelation
279.7 ng/72 hrs in control
group
Blood Pb levels not
mentioned.
Higher mean EDTA chelatable Pb level in Gp 3;
5 of 12 had history of gout developing after CRI.
Limitations = small sample sizes, limited analyses.
Rates of progression of renal insufficiency were
followed by reciprocal of serum creatinine during the
12 mos prior to therapy and for 12 mos following
therapy. Rates of progression of renal insufficiency
were similar in the treatment group and the control
group during the baseline observation. However,
improvement in renal function was observed during
EDTA chelation. Following chelation, renal function
stabilized in the treated group but continued to decline
in the control group. At 12 mos after treatment, the
mean difference in the change in the reciprocal of
serum creatinine between the two groups was
0.000042 L/nmol per mo (95% CI: 0.00001,
0.00007). Results using a sensitivity analysis for
patients lost to follow-up (only one in each group)
gave similar results.
-------
Table AX6-4.3 (cont'd). Renal Effects of Lead in the Patient Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Linetal. (200la)
Taiwan
Study date not
provided
X
24 mo prospective observational study
110 patients with CRI dichotomized by EDTA chelatable
Pb level of 80 ug/72 hrs into two groups of 55 each.
Eligibility criteria included serum creatinine from 1.5-4.0
mg/dL, stable renal function (decrease in GFR <5 mL/min
over 6 mos); blood pressure < 140/90 mm Hg; cholesterol
level <240 mg/dL; daily protein intake <1 g/kg body wt;
no known history of exposure to Pb or other heavy metals
and EDTA chelatable Pb <600 ng/72 h.
Exclusionary criteria included potentially reversible or
unstable renal disease (i.e., due to systemic diseases such
as lupus and diabetes), nephrotoxicant medications, and
drug allergies.
196 patients initially screened for study; details on reasons
for non-eligibility not provided.
Primary outcome =1.5 times increase in the initial
creatinine level or need for dialysis; secondary outcome =
change in creatinine clearance.
Cox proportional-hazards model analysis for primary
outcome. Mean differences in creatinine clearance
compared at sequential time points with t or Mann-
Whitney U tests.
Adjustment for age, gender, baseline BMI, smoking,
proteinuria, hypertension, hyperlipidemia, daily protein
intake, and underlying renal disease.
Intention-to-Treat and sensitivity analyses compared
creatinine clearance a by time period in high and low Pb
groups.
Mean blood Pb levels
6.6 ug/dL in high normal Pb
body burden group (n = 55)
3.9 ug/dL in low normal Pb
body burden group (n = 55)
Mean EDTA chelatable Pb
levels pre-chelation
182.9 ug/72 hrs in high normal
Pb body burden group (n = 55)
37.9 ug/72 hrs in low normal
Pb body burden group
(n = 55)
24 mo prospective observational study
Pb dose measures were only significant differences
between high and low normal Pb body burden groups.
Of the 96 participants who completed the observation
study, 14 patients in the high normal body Pb burden
group reached the primary endpoint compared to 1
patient in the low body Pb burden group (p < 0.001 by
log-rank test).
From mo 12 to mo 24, creatinine clearance in high
normal body Pb burden patients was at least
borderline statistically lower than in low body Pb
burden patients; from 18-24 mos, 95% CI excluded 0.
95% CI for the difference at 24 mos was (-15.0, !3.8);
difference in creatinine clearance between groups was
0.15 mL/s at that point.
In a Cox multivariate regression analysis, chelatable
Pb was significantly associated with overall risk for
the primary endpoint (RR = 41.5 [95% CI: 3.9,
440.8]; p = 0.002). In this model, age, basal BMI, and
basal daily proteinuria were also associated with
increased risk.
-------
Table AX6-4.3 (cont'd). Renal Effects of Lead in the Patient Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Linetal. (200la)
(cont'd)
X
3 mo clinical trial of chelation with 1 vr follow-up
At 24 mos, 36 patients whose EDTA chelatable Pb levels
were 80 - 600 (ig/72 hrs and serum creatinine levels of
<4.2 mg/dL were randomized; 24 to a 3-mo treatment
period consisting of weekly chelation with 1 g EDTA iv
until their excreted Pb levels fell below 80 |J.g/72 hrs and
12 to placebo infusion.
Intention-to-Treat and sensitivity analyses compared
creatinine clearance by time period in treated and control
groups.
3 mo clinical trial of chelation with 1 vr follow-up
The two groups were similar in baseline renal risk
factors (although numbers small so beta error
possible).
Mean EDTA dose during the 3 mo period was 5 |ig.
After three mos of Pb chelation therapy, the body Pb
burden of the patients in the chelation group
decreased from 198 to 39.2 \ig. After 3 mos of
chelation and 3 mos of follow-up, creatinine clearance
increased by 0.08 mL/s in the treated group but
declined by 0.04 mL/s in the controls.
At the end of the study period, mean creatinine
clearance was 0.68 mL/s in the chelated group
compared to 0.48 mL/s in the control group
(p < 0.05; 95% CI for the difference between
groups = -25.0 to-0.2).
-------
Table AX6-4.3 (cont'd). Renal Effects of Lead in the Patient Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Linetal. (200 Ib)
Study location and
date not provided;
authors from Taiwan
X
101 patients with CRI (defined as serum creatinine
between 1.5 and 3.0 mg/dL).
67 with CRI and gout.
34 with CRI only.
Eligibility criteria included no known history of Pb
exposure, certain diagnoses, and medications. CRI must
have preceded gout diagnosis.
Randomized chelation trial
30 participants with CRI, gout, and EDTA-chelatable Pb
levels between 80.2 and 361 (ig/72 hrs randomized to
either a treatment group receiving 1 gram EDTA iv per wk
for 4 wks (N = 20) or to a control group who received
glucose in normal saline iv.
Mean blood Pb
5.4 ug/dL (CRI and gout)
4.4 ug/dL (CRI only)
Mean EDTA-chelatable Pb
138.1 ug/72 hrs (CRI and
gout)
64.2 ug/72 hrs (CRI only)
(p<0.01)
In 101, EDTA-chelatable Pb higher in patients with
CRI and gout compared to those with CRI only.
EDTA-chelatable Pb, but not blood Pb, was
associated positively with serum urate and negatively
with daily urate excretion, urate clearance, and
fractional urate excretion.
Randomized chelation trial
The two groups had similar uric acid, renal function,
and Pb measures pre-chelation. In the treated group,
mean EDTA-chelatable Pb declined from 159.2 to
41 |ig/72 hrs; mean serum urate decreased from 10.2
to 8.6 mg/dL (% change compared to the control
group = !22.4 [95% CI: 146.0, !1.5]; p = 0.02), and
mean urate clearance increased from 2.7 to
4.2 mL/min (% change compared to the control group
= 67.9 [95% CI: 12.2, 121.2]; p< 0.01). Daily and
fractional urate excretion were also significantly
different between the two groups. Mean measured
creatinine clearance increased from 50.8 to
54.2 mL/min (% change compared to the control
group = 8.0 [95% CI: 10.4, 20.1]; p = 0.06).
-------
Table AX6-4.3 (cont'd). Renal Effects of Lead in the Patient Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Lin et al. (2002)
Study location and
date not provided;
authors from Taiwan
X
Oi
84 healthy participants.
27 participants with gout.
All with normal renal function (defined as serum
creatinine <1.4 mg/dL).
Participants with a history of occupational heavy metal
exposure, EDTA-chelatable Pb levels >600 jag/72 hrs, or
systemic diseases were excluded.
Randomized chelation trial
24 participants with EDTA-chelatable Pb levels between
75 and 600 |ig/72 hrs randomized to either a treatment
group receiving 1 gram EDTA iv per wk for 4 wks
(N = 12) or to a control group who received glucose in
normal saline i.v.
Multiple linear regression, adjustment for age, sex, BMI,
daily protein intake, and creatinine clearance.
Mean blood Pb
3.9 ug/dL (controls)
4.2 ug/dL (gout)
Mean EDTA-chelatable Pb
45 ug/72 hrs (controls)
84 ug/72 hrs (gout)
(p< 0.0001)
Significantly higher mean EDTA-chelatable Pb and
lower urate clearance were present in patients with
gout compared to those without (3.7 vs. 6.0 mL/min
/1.73 m2; p < 0.001 for urate clearance).
After adjustment, EDTA-chelatable Pb associated
with all four uric acid measures (serum urate, daily
urate excretion, urate clearance, and fractional urate
excretion). Blood Pb associated with serum urate.
All associations in same direction as in Lin et al.
(2001).
Randomized chelation trial.
The two groups had similar urate, renal function, and
Pb measures pre-chelation. In the treated group, mean
blood and EDTA-chelatable Pb levels declined (from
5.0 to 3.7 |ig/dL and 110 to 46 (ig/72 hrs,
respectively). Statistically significant improvement
observed in all four urate measures in the treated
group compared to the control group.
-------
Table AX6-4.3 (cont'd). Renal Effects of Lead in the Patient Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Lin et al. (2003)
Study location and
date not provided;
authors from Taiwan
X
24 mo prospective observational study
202 patients with CRI
Eligibility criteria included serum creatinine from 1.5-3.9
mg/dL, stable renal function (decrease in GFR <5 mL/min
over 6 mos); blood pressure < 140/90 mm Hg; cholesterol
level <240 mg/dL; daily protein intake <1 g/kg body wt;
no known history of exposure to Pb or other heavy metals
and EDTA chelatable Pb <600 jag/72 h.
Exclusionary criteria included potentially reversible or
unstable renal disease (i.e., due to systemic diseases such
as lupus and diabetes), nephrotoxicant medications, and
drug allergies.
250 patients initially observed, loss due to noncompliance
or unstable renal function, baseline data on the 48 who left
or were removed from the study not provided.
Cox proportional-hazards model analysis for primary
outcome. Generalized estimating equations (GEE) for
associations between baseline chelatable Pb or blood Pb
level and longitudinal change in GFR (estimated by an
MDRD equation [Levey et al., 1999]) and by measurement
of creatinine clearance.
Adjustment for age, gender, baseline BMI, smoking,
baseline serum creatinine, proteinuria, hypertension,
hyperlipidemia, daily protein intake, and underlying renal
diseases.
Mean blood Pb levels
5.3 ug/dL in total group
(n = 202)
6.1 ug/dL pre-chelation in
chelated group (n = 32)
5.9 ug/dL pre-chelation in
control group
Mean EDTA chelatable Pb
levels pre-chelation
104.5 ug/72 hrs in total group
(n = 202)
150.9 ug/72 hrs pre-chelation
in chelated group
144.5 ug/72 hrs pre-chelation
in control group
24 mo prospective observational study
Primary endpoint = increase in serum creatinine to 1.5
times baseline or need for hemodialysis; occurred in
24 participants. Secondary endpoint = change in
estimated glomerular filtration rate (GFR).
In a Cox multivariate regression analysis, chelatable
Pb was significantly associated with overall risk for
the primary endpoint (hazard ratio for each 1 jig
chelatable Pb was 1.00 [95% CI: 1.00, 1.01];
p = 0.03). In this model, baseline serum creatinine
was also associated (hazard ratio for each 1 mg/dL
was 2.75 [95% CI: 1.46, 5.18]; p = 0.002) and, at
borderline significance (p < 0.1), baseline daily
protein excretion and smoking were as well.
The association between baseline chelatable Pb and
change in GFR was modeled using GEE. Estimate =
!0.003 (p = <0.001) (neither SE nor CI provided). In
this model, gender and daily protein intake were
associated with increased GFR; baseline serum
creatinine level, daily urinary protein excretion, and
the presence of polycystic kidney disease were
significant predictors of a progressive decline in
glomerular filtration rate.
Based on this model, a 10 |ig higher baseline
chelatable Pb level was associated with a GFR
decrease of 0.03 mL per minute per 1.73 m of body-
surface area during the 2 yr observation period.
Although statistically significant, this effect is
clinically small. Furthermore, it is 40 fold lower than
that reported in Yu et al. (2004) over a follow-up
period that is only two-fold shorter.
-------
Table AX6-4.3 (cont'd). Renal Effects of Lead in the Patient Population
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Lin et al. (2003)
(cont'd)
Study location and
date not provided;
authors from Taiwan
27 mo clinical trial of chelation
At 24 mos, 64 patients whose EDTA chelatable Pb levels
were 80 - 600 (ig/72 hrs and serum creatinine levels of
<4.2 mg/dL were randomized; half to a 3-mo treatment
period consisting of weekly chelation with 1 g EDTA iv
until their excreted Pb levels fell below 60 l-ig/72 hrs and
half to five wks of placebo infusion.
Intention-to-Treat analysis compared creatinine clearance
and GFR by time period in treated and control groups.
X
oo
27 mo clinical trial of chelation
The two groups were similar in baseline renal risk
factors (although numbers small so beta error
possible).
After three mos of Pb chelation therapy, the body Pb
burden of the patients in the chelation group
decreased from 150.9 to 43.2 ug and their mean blood
Pb levels decreased from 6.1 to 3.9 ug/dL. GFR
increased by 3.4 mL/min/1.73 m2 in the treated group;
in contrast, it decreased by 1.1 mL/min/1.73 m in the
control group. Mean EDTA dose during the 3 mo
period was 5.2 ug.
In the subsequent 24 mos, chelation in 19 (59%)
participants was repeated due to increases in serum
creatinine in association with rebound increases in
EDTA chelatable Pb levels. Each received one
additional chelation series (mean 4.1 g EDTA) a mean
of 13.7 mos after the first chelation period. Control
patients receiving placebo weekly for five wks every
At the end of the study period, mean estimated
glomerular filtration rate increased by 2.1
mL/min/1.73 m2 of body-surface area in the chelated
group compared to a decline of 6.0 in the controls
(p < 0.01; 95% CI for the difference between groups =
-11.0 to-5.1).
-------
Table AX6-4.3 (cont'd). Renal Effects of Lead in the Patient Population
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Yu et al. (2004)
Study location and
date not provided;
authors from Taiwan
X
121 patients followed over a four yr observational
period.
Eligibility criteria included serum creatinine from 1.5
-3.9 mg/dL, stable renal function (decrease in GFR <5
mL/min over 6 mos); blood pressure < 140/90 mm Hg;
cholesterol level <240 mg/dL; daily protein intake <1
g/kg body wt; no known history of exposure to Pb or
other heavy metals and EDTA chelatable Pb <600
Hg/72 h.
Exclusionary criteria included potentially reversible or
unstable renal disease (i.e., due to systemic diseases
such as lupus and diabetes), medical noncompliance
(patients were followed for 6 mos to assess
compliance before enrollment in the study),
nephrotoxicant medications, and drug allergies.
Cox proportional hazards model analysis for primary
outcomes and generalized estimating equations (GEE)
for associations between baseline chelatable Pb or
blood Pb level and longitudinal change in GFR
(estimated by an MDRD equation [Levey et al.,
1999]).
Adjustment for age, gender, baseline BMI, smoking,
baseline serum creatinine, proteinuria, hypertension,
hyperlipidemia, daily protein intake, use of ACE
inhibitor or angiotensin-receptor antagonists (since
not all patients were on these), and chronic
glomerulonephritis (other underlying renal diseases
included in GEE as well).
Mean (SD) blood Pb at baseline
3.4 (1.3) ng/dL in 58 patients
with "low-normal" EDTA
chelatable Pb levels (<80 \ig
Pb/72 hrs)
4.9 (2.6) ng/dL in 63 patients
with "high-normal" EDTA
chelatable Pb levels (380 but
<600 jag/72 hrs)
The two groups (dichotomized by diagnostic EDTA chelatable
Pb of 80 |ig Pb/72 hrs ) were similar in most baseline risk factors
other than Pb body burden. Borderline statistically significant
(p < 0.1) differences included mean older age in the high
chelatable Pb group and certain renal diagnoses (chronic
glomerulosclerosis, chronic interstitial nephritis, hypertensive
nephropathy; surprisingly both of the latter two diagnoses were
less common in the lower Pb body burden group).
Fifteen patients in the "high-normal" chelatable Pb group
reached the primary endpoint (doubling of serum creatinine over
the 4 yr study period or need for hemodialysis) compared to only
two in the "low-normal" group (p = 0.001 by Kaplan-Meier
analysis).
In a Cox multivariate regression analysis, chelatable Pb was
significantly associated with overall risk for the primary
endpoint (hazard ratio for each 1 jig chelatable Pb was 1.01
[95% CI: 1.00, 1.01]; p = 0.002). In this model, the only other
variable reaching at least borderline significance (p < 0.1) was
baseline serum creatinine.
The associations between baseline chelatable Pb or blood Pb
level and change in GFR were modeled separately using GEE.
3 = 10.1295 (p = 0.002) for Pb body burden
3 = 14.0123 (p = 0.02) for blood Pb
Based on these models, a 10 |j,g higher baseline chelatable Pb
level or l|j,g/dL higher blood Pb level predicted 1.3 and 4.0
mL/min declines in GFR, respectively, during the four yr study
period. Similar to the primary outcome analysis, of the many
traditional renal risk factors adjusted for in these models, only
diagnosis of chronic interstitial nephritis was significantly
associated, in this case with an increase in GFR. Of note,
chronic interstitial nephritis was also a more frequent diagnosis
in the group with the low-normal chelatable Pb levels (p = 0.09).
The authors stated that these patients were not included in earlier
publications (which are described below in Section 6.4.4.3.3
Therapeutic EDTA Chelation in Patients).
-------
Table AX6-4.4. Renal Effects of Lead on Mortality
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
X
to
o
United States
Cooper (1988);
Cooper etal. (1985)
16 U.S. plants
Employment between
1946 and 1970;
mortality from 1947
to 1980
4519 male battery plant workers.
2300 male Pb production workers.
Employed for at least one yr between 1946 and 1970.
Cause of death per death certificate (extrapolated when
missing).
Standardized mortality ratios (SMRs) compared with
national age-specific rates. PMR also assessed.
Analyzed separately by battery and Pb production, by hire
date before and after 1/1/1946, and by cumulative yrs of
employment (1-9, 10-19,20+).
Steenland et al. (1992) 1990 male Pb smelter workers.
Idaho
Employed between
1940 and 1965;
mortality up to 1988
Employed in a Pb-exposed department for at least one yr
between 1940 and 1965.
Vital status was determined using records from the Social
Security Administration and the National Death Index.
Mean blood Pb
63 ug/dL in n = 1326 battery
workers
80 ug/dL in n = 537
production workers
Past Pb exposures poorly
documented prior to 1960
Mean blood Pb
56.3 ug/dL (n = 173, measured
in 1976)
High Pb exposure defined as
workers from departments
with an avg >0.2 mg/m3
airborne Pb or 350% of jobs
had avg levels more than twice
that level (1975 survey). In
this category, n = 1,436.
Follow-up >90% in both groups; 2339 deaths
observed.
"Chronic or unspecified nephritis" SMR:
222 (95% CI: 135, 343) in battery workers
265 (95% CI: 114, 522) in Pb production workers
"Other hypertensive disease" SMR ("includes HTN
and related renal disease without mention of heart
disease)":
320 (95% CI: 197, 489) in battery workers
475 (95% CI: 218, 902) in Pb production workers
Race adjusted proportionate mortality ratios analyses
similar.
Nephritis deaths observed primarily in workers hired
before 1946.
Limitations = due to mortality analysis (inaccuracies
of death certificates, exposure assessment generally
limited).
Compared to the U.S. white male population, the
standardized mortality ratio (SMR) for chronic kidney
disease, based on only 8 deaths, was 1.26 (95%
CI = 0.54, 2.49). SMR = 1.55 in high Pb exposure
group, also not significant. The SMR for chronic
kidney disease increased with duration of exposure
from 0.79 in workers exposed 1-5 yrs to 2.79 in
workers exposed >20 yrs; however SMR was not
significant.
-------
Table AX6-4.4 (cont'd). Renal Effects of Lead on Mortality
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Europe
Faming (1988)
UK
Deaths from
1926-1985
Deceased males identified through pension records of Pb
battery and other factory workers.
867 deaths of mean with high Pb exposure compared to
1206 men with low or no Pb exposure.
Range of blood Pb
40-80 ug/dL since -1968 in
high Pb exposure group;
thought not to have had
clinical Pb poisoning due to
medical surveillance.
<40 ug/dL since -1968 in little
or no exposure group.
Odds ratio for renal disease = 0.62, not significant,
based on only 11 deaths. Similar for diagnosis of
nephritis. Possible decreasing odds ratio over time of
deaths with mention of nephritis on death certificate
but not significant and numbers still quite small.
Limitations = standard mortality study issues
although deaths compared with other workers and not
general population which is a strength in this type of
study.
X
-------
Table AX6-4.5. Renal Effects of Lead in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
X
to
to
United States
Hu(1991)
U.S.
Study date not
provided
21 of 192 adults who were hospitalized at Boston
Children's Hospital between 1932 to 1942 for childhood
Pb poisoning were traced to a Boston area address.
Matched on age, sex, race, and neighborhood to
21controls.
Mean (SD) blood Pb
6.0 ug/dL (Pb poisoned)
7.5 ug/dL (controls)
Loghman-Adham
(1998)
Chicago, IL
Study date not
provided
134 children and young adults, 8 to 13 yrs after chelation
therapy for severe Pb poisoning.
Mean age at poisoning = 2.3 yrs
Mean age at follow-up =13.4 yrs
Mean peak blood Pb level
121 ug/dL
Mean blood Pb level at time
of study
18.6 ug/dL
No significant differences in blood Pb level, serum
creatinine, or BUN. Mean measured creatinine
clearance higher in the previously Pb poisoned group
compared to controls (112.8 vs. 88.8 mL/min/1.73 m2
[p < 0.01]). Mean in the Pb exposed group was also
higher than the predicted value of 94.2 mL/min/1.73
m2 from the nomogram of Rowe et al. (1976).
Suggests Pb-related hyperfiltration. As noted in
section 6.4, one survivor, identified but not included
in the study, had disease consistent with Pb
nephropathy.
Limitations = small study size and concern for
survivor bias in the study group.
Mean serum creatinine was normal (0.8 mg/dL).
Calculated creatinine clearance normal in all but 3
children. No correlation between either initial or
current blood Pb and serum creatinine or calculated
creatinine clearance.
Urinary a-amino nitrogen concentrations were
significantly increased compared with 19 healthy age
matched controls and were correlated with current
blood Pb levels. Thirty-two children (24%) had
glycosuria. Fractional excretion of phosphate,
however, was normal in all children. The author
concluded that a partial Fanconi syndrome could
persist for up to 13 yrs after childhood Pb poisoning.
The author notes that the prognostic significance of
this is unknown at present.
-------
Table AX6-4.5 (cont'd). Renal Effects of Lead in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Europe
McDonald and Potter
(1996)
Boston, MA
1991
Moel and Sachs (1992)
Chicago, IL
1974-1989
X
to
Bernard etal. (1995b)
Czech Republic
Study date not
provided
454 pediatric hospital patients who were diagnosed with
Pb poisoning between 1923 and 1966 were traced
through 1991.
Mortality study, comparison with U.S. population.
62 participants with blood Pb >100 ug/dL, diagnosed and
chelated between 1966 and 1972, together with 19 age-
matched control siblings with initial blood Pbs less than
40 ug/dL. Mean age at follow-up = 22 yrs.
Renal outcomes = serum creatinine, uric acid, and 32-
microglobulin, fractional excretion of 32-microglobulin,
urinary protein: creatinine ratio, and tubular reabsorption
of phosphate.
144 children living close to a Pb smelter (exposed groups
1 and 2).
51 controls living in a rural area presumed to be
relatively unpolluted with Pb.
Mean age = 13.5 yrs.
Renal outcome measures included urinary albumin, RBP,
NAG, Clara cell protein, and 32-microglobulin.
Retinol binding protein
73.8 ug/g creatinine (controls)
109.4 ug/g creatinine (exposed group 1)
117.8 ug/g creatinine (exposed group 2)
39-microglobulin
60.3 ug/g creatinine (controls)
89.1 ug/g creatinine (exposed group 1)
66.4 ug/g creatinine (exposed group 2)
NAG
1.56 lU/g creatinine (controls)
2.32 lU/g creatinine (exposed group 1)
1.46 lU/g creatinine (exposed group 2)
Multiple linear adjusting for age and gender.
Mean initial blood Pb
150.3 ug/dL (highly poisoned
as children)
Data for siblings not available
as levels <40 ug/dL not
quantified.
Blood Pb
8.7 ug/dL (control boys)
8.39 ug/dL (control girls)
10.9 ug/dL (exposed boys 1)
9.4 ug/dL (exposed girls 1)
14.9 ug/dL (exposed boys 2)
12.9 ug/dL (exposed girls 2)
Chronic nephritis was not a significant cause of death.
Mortality from all cardiovascular disease was
elevated (observed/expected = 2.1 [95% CI: 1.3,
3.2]) and cerebral vascular deaths were particularly
common among women (observed/expected =5.5
[95% CI: 1.1,15.9]).
There were no statistical differences in either renal
function or blood pressure between study subjects and
control siblings. Initial blood Pb level was not
associated with serum creatinine, after adjustment for
age, gender, and body mass index. A modest increase
in serum creatinine values was observed over a nine-
yr period in four of the 62 study subjects (up to
1.6mg/dL).
Mean blood Pb levels significantly higher in both
exposed groups compared to the control group. In
contrast, blood cadmium levels were similar among
all groups. After adjustment for age, sex, blood
cadmium, and zinc protoporphyrin, log transformed
blood Pb was associated with log transformed RBP
(3 = 0.302,p = 0.005).
-------
Table AX6-4.5 (cont'd). Renal Effects of Lead in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
X
to
Europe (cont'd)
De Burbure et al.
(2006)
France, the Czech
Republic, and Poland
Study date not
provided
Factor-Litvak et al.
(1999)
Kosovo, Yugoslavia
1985-1993
804 exposed and control children.
Exposed children recruited from residents near historical
nonferrous smelters, must have lived 38 yrs near
smelters.
Mean age = 10 yrs; range = 8.5-12.3 yrs.
Renal outcome measures included serum creatinine,
cystatin C and B2-microglobulin as well as urinary RBP,
NAG, Clara cell protein.
577 children followed at 6 mo intervals through 7.5 yrs
of age.
Divided into a high exposure and a low exposure group,
based on residence in Kosovska Mitrovica with a Pb
smelter, refinery, and battery plant or in Pristina, 25 miles
away.
Renal outcome = Proteinuria assessed with a dipstick.
Multiple logistic regression modeling of proteinuria
dichotomized as either any or none, adjusting for
socioeconomic status, maternal education/ intelligence,
and quality of childrearing environment.
Mean blood Pb
Ranged from 2.8 to 4.2 mg/dL
in various control and exposed
groups.
Urinary cadmium, arsenic and
mercury as well as blood
cadmium also assessed.
Mead blood Pb from graph
peaked at -38 ug/dL between
ages 3-5 in Kosovska
Mitrovica and at -10 ug/dL in
controls.
Blood Pb level ranged from
1 to 70 ug/dL.
Serum concentrations of creatinine, cystatin C, and
B2-microglobulin negatively correlated with blood Pb
levels.
Authors state suggestive of an early renal
hyperfiltration that avgd 7% in the upper quartile of
PbB levels (>5.5 ug/dL; mean 7.84 ug/dL).
In higher exposed group, adjusted OR for proteinuria
was 3.5 (95% CI: 1.7, 7.2); adjusted odds of
proteinuria increased by 1.15 (95% CI: 1.1,1.2) per
unit increase in blood Pb in the higher exposed group.
Proteinuria unrelated to blood Pb in lower exposed
control group.
Limitations = limited renal outcomes assessed, high
dropout rate in the study.
-------
Table AX6-4.5 (cont'd). Renal Effects of Lead in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Pels etal. (1998)
Poland
1995
X
to
_ktem et al. (2004)
Turkey
Study date not
provided
112 children (50 controls, 62 exposed).
Mean age =9.9 yrs and 10.6 yrs in controls and exposed
group, respectively.
Numerous (29) renal outcome measures were examined
including serum creatinine and 32-microglobulin, and
urinary NAG, RBP, Clara cell protein, 32-microglobulin,
6-keto-prostaglandin Fla (6-keto-PGFla), prostaglandin
E2 (PGE2) and thromboxane B2 (TXB2).
Urinary RBP
46 ug/g creatinine (exposed)
42 ug/g creatinine (controls)
Urinary 3rmicroglobulin
89 ug/g creatinine (exposed)
37 ug/g creatinine (controls)
Serum creatinine
0.63 mg/dL (exposed)
0.63 mg/dL (controls)
79 adolescent auto repair workers (mean age 17.3 yrs).
71 rural adolescents as negative controls (mean age 17.0
yrs).
Renal outcomes = urinary NAG, 32-microglobulin, uric
acid, and calcium; blood urea nitrogen (BUN), serum
creatinine and uric acid.
Mean blood Pb
13.3 ug/dL (exposed)
3.9 ug/dL (controls)
Mean blood Pb
7.79 ug/dL (exposed workers)
1.6 ug/dL (controls)
Significantly higher mean serum 32-microglobulin,
and urinary transferrin, 6-keto-PGFla, thromboxane
B2, epidermal growth factor, 32-microglobulin, PGE2,
and Clara cell protein in the exposed children. In
contrast, NAG-B was lower in the exposed group.
Categorical blood Pb associated with prevalence of
values above the upper reference limits for several
biomarkers. Urinary 6-keto-PGFla, TXB2, 32-
microglobulin, Clara cell protein, epidermal growth
factor and PGE2 positively correlated with blood Pb
(r = 0.441, 0.225, 0.203, 0.261, 0.356, and 0.23,
respectively; all with significant p-values).
Limitations = data analysis, limited adjustment.
No difference in mean BUN, serum creatinine, uric
acid, or GFR (apparently estimated) between workers
and controls.
Urinary NAG and calcium significantly higher in
workers compared to controls. Urinary NAG
positively correlated blood Pb (r = 0.427).
Limitations = data analysis, lack of adjustment.
-------
Table AX6-4.5 (cont'd). Renal Effects of Lead in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
X
Oi
to
Oi
Europe (cont'd)
Price etal. (1999)
Belgium, Poland,
Germany and Italy
Study date not
provided
Schsreretal. (1991)
Germany
1988-1989
S nmez et al. (2002)
Turkey
Study date not
provided
Urinary Pb measured in 481 European children (236
controls, 245 exposed) aged 6-14 yrs.
Several renal outcome measures assessed including
urinary NAG and 32-microglobulin; values not reported.
22 children, age 5-14 yrs, with CRI.
20 siblings or neighbors as lower exposed group.
16 control children without known Pb exposure.
39 adolescent auto repair workers (mean age 16.2 yrs).
13 adult battery workers as positive controls (mean age
32 yrs).
29 rural adolescents as negative controls (mean age
14.8 yrs).
Serum creatinine
0.99 mg/dL (exposed group)
0.99 mg/dL (positive/ adult controls)
0.89 mg/dL (negative/ adolescent controls)
Urinary NAG
4.7 lU/g creatinine (exposed group)
7.4 lU/g creatinine (positive/ adult controls)
3.1 lU/g creatinine (negative/ adolescent controls)
Mean urinary Pb
Range from 3.9 to 7.2 ug/g
creatinine (controls)
Range from 5.2 to 24.6 ug/g
creatinine (exposed)
Mean blood Pb
2.9 ug/dL in children with
CRI, not tested in other groups
Mean dental Pb content
2.8 ug/g in children with CRI
1.7 ug/g in sibs/neighbors
1.4 ug/g in controls
Mean blood Pb
8.13 ug/dL (exposed group)
25.3 ug/dL
(positive/adult controls)
3.49 ug/dL
(negative/ adolescent controls)
Urinary Pb generally higher in exposed children as
compared to controls. Authors unexpectedly found
substantial differences in renal biomarkers by study
site. Authors note several renal biomarkers differed
between exposed and control groups. Also
questioned the use of "control" groups in ubiquitous
exposures.
Pb levels in teeth significantly higher in both the
patient and sibling/neighbor control groups compared
to the unexposed control group.
All participants had normal blood urea, creatinine,
and uric acid levels as well as normal routine
urinalysis.
Blood Pb level and urinary NAG significantly higher
in adolescent auto repair workers compared to the
negative control group.
Limitations = data analysis, lack of adjustment.
-------
Table AX6-4.5 (cont'd). Renal Effects of Lead in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Staessen et al. (2001)
Belgium
1999
X
to
Verberketal. (1996)
Romania
1991-1992
100 exposed and 100 control children.
Mean age = 17 yrs.
Two exposed groups were recruited from industrialized
suburbs while the control group was recruited from a rural
area.
B^-microglobulin
5.22 ug/mmol creatinine (controls)
5.3 ug/mmol creatinine (exposed group 1)
9.09 ug/mmol creatinine (exposed group 2)
Cystatin-C
0.65 mg/L (controls)
0.63 mg/L (exposed group 1)
0.71 mg/L (exposed group 2)
Multiple linear regression adjusting for sex and smoking
status.
151 children who resided at different distances from a Pb
smelter.
Mean age = 4.6 yrs.
Renal outcomes = urinary RBP, NAG, apmicroglobulin,
albumin and alanine aminopeptidase.
Geometric means
Urinary RBP
49.4 ug/g creatinine
Urinary NAG
6.9 U/g creatinine
Urinary q^-microglobulin
2.4 mg/g creatinine
Urinary alanine aminopeptidase
19.8 U/g creatinine
Mean blood Pb
1.5 ug/dL (controls)
1.8 ug/dL (exposed group 1)
2.7 ug/dL (exposed group 2)
Mean (SD) blood Pb
34.2 (22.4) ug/dL
Blood Pb, 32-microglobulin, and Cystatin-C levels
higher in exposed group 2 as compared to controls and
exposed group 1.
After adjustment for sex and smoking status, blood Pb
was associated with both 32-microglobulin and
cystatin-C. A two-fold increase in blood Pb was
associated with a 3.6% (95% CI: 1.5, 5.7) increase in
Cystatin-C and a 16% (95% CI: 2.7, 31) increase in
32-microglobulin. Blood cadmium was not associated
with either outcome.
After adjustment for age and gender, a 10 ug/dL
increase in blood Pb was associated with a 13.5%
increase in NAG excretion (90% CI: 10.2,17).
No threshold was observed. No other significant
associations noted.
Multiple regression analysis adjusting for age and gender.
-------
X
Table AX6-4.5 (cont'd). Renal Effects of Lead in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Africa
Dioufetal. (2003)
Senegal
1998
38 Senegalese children (19 exposed, 19 controls).
Age range = 8 - 12 yrs old.
Renal function assessed by measuring urinary alpha-
glutathione S-transferase (aGST).
Mean (SD) blood Pb
10.7 (1.7) ng/dL (exposed)
6.1(1.8) ng/dL (controls)
Blood Pb significantly higher in exposed group (urban
dwellers) as compared to controls (rural dwellers).
Unclear as to whether aGST was higher or lower in
controls as compared to exposed group (stated to be
higher in controls in the results section BUT stated to be
higher in the exposed group in the discussion).
Regardless, the difference was not statistically
significant.
Limitations = small sample size, data analysis.
to
oo
-------
ANNEX TABLES AX6-5
AX6-129
-------
Table AX6-5.1. Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
Meta-analysis
Nawrot et al. (2002)
31 U.S. and European
studies, community
and occupationally
exposed, published
between 1981 and
2001.
48 different groups, 32 of which
were only of men, 15 of which were
only of women, and one studying
both sexes. Total meta-analysis
N> 58,490. Age ranged from 15 to
93 yrs, depending on the study.
Two methods of meta-analysis were
used, subject-weighted and non-
weighted, using study-reported
effect sizes and standard errors,
transformed from the original study
specification of blood Pb (linear,
logarithmic, or blood Pb group) to a
single effect size for doubling of
blood Pb. Also did analyses
stratified by race and sex.
Mean blood Pb concentration Each doubling of blood Pb was associated with a significant 1.0 mm Hg
across studies ranged from
2.3 to 63.8 ug/dL. Total
range of blood Pb across
studies was 0 to 97.9 ug/dL.
(95% CI: 0.5, 1.4) increase in systolic blood pressure and a significant 0.6
mmHg(95%CI: 0.4, 0.8) increase in diastolic blood pressure. Stated that
differences in Pb effect were not statistically different between sexes, but did
not describe test nor give statistics other than p-values. Presented black and
white differences as a trend for blacks to be "more susceptible than whites,"
but presented no tests.
Statistically examined assumptions of homogeneity of effect and found no
significant heterogeneity. Tested for publication bias (statistically significant
results tend to be published more than non-significant results) and found no
evidence. Found no significant effects of removing one study at a time in
sensitivity analysis. It appears that the presented results of effect sizes and
confidence intervals were calculated by the subject-weighted method, but this
was not made explicit. Included some studies that presented no Pb
coefficients or standard errors, assuming effect size of zero, though the
reported effect sizes without these studies did not appear to be different from
overall effect sizes. For studies using a linear Pb measure, effect sizes were
calculated by doubling the arithmetic mean blood Pb. If the concentration-
response curve for the Pb-blood pressure relationship was really better
characterized by a log-linear function, the authors' use of studies with a linear
blood Pb term with high avg blood Pb led to over-estimation of the slope of
the relationship and those studies with low blood Pb avgs produced an under-
estimation of the slope of the relationship.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
United States
Cheng etal. (2001)
U.S.-Boston,
Normative Aging
Study (VA)
1991-1997
X
833 males (—97% white), avg age
(SD):
65.5 (7.2) Normotensive subjects,
N=337
68.3 (7.8) Borderline hypertensive
subjects, N= 181
67.9 (6.8) Definite hypertensive
subjects, N= 314
474 males with no history of
hypertension at first measurement,
returning up to 6 yrs later for
hypertension study.
Linear multiple regression models of
blood pressure and Cox proportional
hazard models of new cases of
hypertension after up to 7 yrs, with
one group of covariates forced into
models based on biological
plausibility and another group
forced based on significant
univariate or bivariate results or
>20% effect modification of Pb
variable coefficient in multiple
models. Linear blood Pb, tibia Pb,
and patella Pb forced in separate
models.
Arithmetic mean (SD) blood
Pb:
5.9-6.4 ug/dL (3.7-4.2),
depending on hypertension
group (only data shown).
Multiple regression models of blood pressure always included age, age-
squared, BMI, family history of hypertension, daily alcohol consumption,
and daily calcium consumption. Increasing tibia Pb concentration was
associated with increased systolic blood pressure (diastolic not addressed) in
baseline measurements in subjects (n = 519) free from definite hypertension
(systolic >160 mm Hg, diastolic >95 mm Hg, or taking daily antihypertensive
medication). Each increase of 10 ng/g tibia Pb concentration was associated
with an increase in systolic blood pressure of 1.0 mm Hg (95% CI: 0.01,
1.99). Patella and linear blood Pb were not significant.
Cox proportional hazard models always included age, age-squared, BMI, and
family history of hypertension. In follow up (n = 474), only increasing
patella Pb predicted increasing risk of definite hypertension in those
classified as normotensive at baseline. For every 10 ng/g increase in patella
Pb risk ratio increased 1.14 (95% CI: 1.02, 1.28). Combining borderline
hypertension (systolic 141-160 mm Hg or diastolic 91-95 mm Hg) with
definite hypertension (n = 306), the relative risk ratio of becoming a
combined hypertensive associated with a 10 ug/g increase in patella Pb was
1.23 (95% CI: 1.03, 1.48). Linear blood Pb and tibia Pb were not
significant.
Linear blood Pb is not indicated for blood pressure models due to strong
likelihood of significant residual heteroscedasticity and non-normality.
Relatively small sample size may have prevented tibia blood Pb significance
in the Cox proportional hazard models.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
United States (cont'd)
Den Hond et al.
(2002)
U.S.-NHANES III
1988-1994
X
to
Gerr et al. (2002)
U.S.-Spokane WA
and area around
Silver Valley ID
1994
4,685 white males, 5,138 white
females, 1,761 black males, 2,197
black females, from 20 yrs up. Log-
transformed blood Pb, systolic and
diastolic blood pressure measured at
survey time and analyzed with
forward, stepwise multiple
regression with covariates.
Avg age:
White
Male: 44.3 yrs
Female: 46.2 yrs
Black
Male: 40.5 yrs
Female: 41.5 yrs
502 young people, age 19-29 yrs,
53% female, nearly evenly divided
into the Spokane group (no unusual
childhood exposure) and the Silver
Valley group, where a Pb smelter
operated during their childhood.
Multiple regression models of
systolic blood pressure and diastolic
blood pressure. All covariates
forced into model as block with both
linear blood Pb and tibia bone Pb in
each model.
Geometric mean
(25th-75th percentile)
blood Pb:
White male mean 3.6 ug/dL
(2.3-5.3)
White female mean 2.1 ug/dL
(1.3-3.4)
Black male mean 4.2 ug/dL
(2.7-6.5)
Black female mean 2.3 ug/dL
(1.4-3.9)
Mean (SD) blood Pb only
given stratified on tibia Pb
category:
Tibia <1 ug/g: 1.9 ng/dL
(1.6)
Tibia 1-5 ug/g: 2.3 ug/dL
(2.1)
Tibia 6-10 ug/g: 2.4 ng/dL
(2.4)
Tibia <10 ug/g: 3.2 ng/dL
(2.3)
No other descriptive tibia Pb
data given.
After adjusting for age, age-squared, BMI, hematocrit, smoking, alcohol, and an
indicator variable for use of antihypertensive medications, each model was
further modified by a unique mix of other covariates, including: coffee
consumption, dietary calcium, dietary sodium/calcium ration, total serum
protein, total serum calcium, diabetes, and poverty index. Log Pb was forced in
last.
In stratified analyses, only blacks had significant positive blood pressure
associations with log blood Pb. Each doubling of blood Pb was associated with
increase of black male systolic blood pressure of 0.9 mm Hg (95% CI: 0.04,
1.8), black female systolic blood pressure of 1.2 mm Hg (95% CI: 0.4, 2.0), and
female diastolic blood pressure of 0.5 mmHg (95% CI: 0.01, 1.1). In white
males only, each doubling of blood Pb was significantly associated with a
decrease in diastolic blood pressure of-0.6 mm Hg (95% CI: -0.9, -0.3).
Stepwise models can rely on chance associations due to multiple testing and
usually lead to a different pattern of covariate adjustment in different models.
Inclusion of likely confounding variables such as serum calcium could have
affected estimated Pb effects. No testing for significant Pb coefficient
differences between each stratum. No model diagnostic tests reported. No
explanation offered for inverse relationship between Pb and diastolic blood
pressure in white males. No adjustment for survey design.
Adjusting for sex, age, height, BMI, education, income, current smoker, current
alcohol use, childhood residence (the two recruitment areas), current birth
control pills, hemoglobin, and serum albumin, only tibia Pb, and not linear blood
Pb, was significantly related to systolic and diastolic blood pressure. Compared
to the <1 ug/g tibia Pb category, subjects in the >10 ug/g category had
4.3 mm Hg (95% CI: 1.4, 6.7) higher systolic blood pressure and 2.8 mm Hg
(95% CI: 0.4, 5.2) higher diastolic blood pressure.
Linear blood Pb is not indicated for blood Pb-blood pressure models.
No diagnostic testing reported. Insufficient descriptive data given for tibia Pb.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
United States (cont'd)
Glenn etal. (2003)
U.S.-New Jersey
1994-1998
X
496 males, mean (SD, range) age
55.8 (7.4,40-71) yrs, working or
formerly working at a plant
producing tetraethyl or tetramethyl
Pb until 1991, were followed from
10 mos to 3.5 yrs during which
blood pressure was repeatedly
tested. Blood Pb was tested only at
baseline. Tibia Pb was tested in
1991 (at the end of organic Pb
production at the plant) and called
"peak tibia Pb" and again during
1997(yr3). Generalized estimating
equations with an exchangeable
correlation structure for repeated
measurements were used for systolic
and diastolic blood pressure. One
group of covariates was forced into
the model as a block (age at
baseline, race, BMI, indicator
variable for technician, Pb variable
(linear blood Pb, peak tibia Pb, and
tibia Pb each tested separately),
duration of follow up, and the
interaction between the Pb variable
and the duration term. Potential
confounding variables were entered
stepwise and retained in the model if
significant. Alternate models not
using linear time were constructed,
using quartile of follow up time to
avoid assuming a linear relationship
of change in blood pressure with
time.
Arithmetic mean (SD, range)
blood Pb at baseline:
4.6 ug/dL (2.6, !lto20)
TibiaPbatyrS:
14.7 ug/g (9.4, ! 1.6 to 52)
Peak tibia Pb:
24.3 ug/g (18.1, !2.2 to
118.8)
Controlling for baseline age, BMI, antihypertensive medication use, smoking,
education, technician and number of yrs to each blood pressure measurement,
each 1 ug/dL increase in linear baseline blood Pb was associated with avg
systolic blood pressure increase of 0.64 mm Hg/yr (95% CI: 0.14,1.14),
each 10 ug/g increase in yr 3 tibia Pb with an avg increase of 0.73 mm Hg/yr
(95% CI: 0.23, 1.23), and each increase of 10 ug/g of peak tibia Pb with an
avg increase of 0.61 mm Hg/yr (95% CI: 0.09,1.13). Similar results were
obtained using the follow up time quartile designation for systolic blood
pressure with all subjects and with subjects not taking antihypertensive
medications.
This was one of the few studies using a prospective design and that used a
statistical technique accounting for repeated measures. No justification given
for using an exchangeable correlation structure instead of an alternate one.
Only examined cortical bone Pb (tibia) and not trabecular bone Pb (patella or
calcaneus). Linear blood Pb may not be indicated for use in blood Pb-blood
pressure models. Stepwise modeling involves multiple testing of the same
data set with no control for altered probabilities. No model diagnostics
presented.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
United States (cont'd)
Glenn et al. 213 males (92% white), mean (SD)
(2001) age 58.0 (7.4) yrs, working or
U.S.-New Jersey formerly working at a plant
1996-1997 producing tetraethyl or tetramethyl
Pb until 1991, were genotyped for
ATP1A2(5') and ATP1A2(3')
polymorphism. ATPase is thought to
play a role in regulating blood
pressure and Pb inhibits its activity.
Blood pressure, blood Pb, and tibia
Pb were measured. Multiple linear
regression models were used for
systolic and diastolic blood pressure.
Logistic regression model was
reported for hypertension
(systolic >160 mm Hg,
diastolic > 96 mm Hg, or taking
antihypertensive medications).
Covariate entry methods not
specified, but were likely stepwise.
Covariates for the blood pressure
model were age, use of
antihypertensive medications,
alcohol, smoking, season of yr, linear
blood Pb, tibia Pb (the two Pb
measures apparently tested
separately), ATP1A2(5') and
ATP1A2(3') polymorphism (each
tested separately), and an interaction
term between polymorphism and Pb.
Covariates for the hypertension
models were age, BMI, lifetime
alcoholic drinks, linear blood Pb and
tibia Pb, and polymorphism, each Pb
measure and polymorphism tested
separately.
Arithmetic mean (SD, range) None of the relationships between the ATP1A2(5') polymorphism and either blood
blood Pb:
5.2 ng/dL (3.1,1-20)
Mean (SD) tibia Pb:
16.3 ng/g (9.3)
or bone Pb or blood pressure were significant.
The ATP1A2(3') polymorphism was homogenous for the 10.5 kilobase allele
(10.5/10.5) in 11 subjects, heterogeneous for the 10.5 and 4.3 kilobase allele
(10.5/4.3) in 82 subjects, and heterogeneous (10.5/4.3) in 116 subjects. Prevalence
of the 10.5 allele was significantly higher in blacks than in whites.
Regression coefficients of 4.3/4.3 and 10.5/4.3 genotypes were not significantly
different and all subsequent analyses compared the 10.5/10.5 genotype with the
combined 4.3/4.3-10.5/4.3) genotype. The significant interaction between linear
blood Pb and the 10.5/10.5 genotype showed that for every 1 ng/dL of blood Pb
systolic blood pressure increased 5.6 mm Hg (95% CI: 1.2, 9.9) more than the blood
pressure of the combined genotype group. Blood Pb range of the combined
genotype group was twice that of the 10.5/10.5 group. When data were truncated to
make blood Pb of both groups cover the same range, coefficients of the genotype-
linear blood Pb interaction term did not change appreciably. Authors state that tibia
Pb interacted with genotype on blood pressure but showed no data to estimate either
type or size of effect. Diastolic blood pressure was not related to genotype, to Pb or
to the interaction between Pb and genotype.
Prevalence of hypertension (30% in total sample) was significantly higher among
the 10.5/10.5 group (63.4 %) than among the combined group (28.3 %). Adjusting
for age, BMI, and lifetime alcohol, the odds of hypertension in the 10.5/10.5 group
were OR = 7.7 (95% CI: 1.9, 31.4) compared to the 4.3/4.3 group. The
heterogeneous group was not significantly different from the 4.3/4.3 group.
Linear blood Pb specification not indicated for blood Pb-blood pressure modeling.
Examination of partial residual plot for systolic blood pressure and linear blood Pb
shows typical heterogeneity of residuals as a function of predicted values. Thus,
presented coefficients may be inefficient and biased. Only 9 subjects were
homogenous for 10.5/10.5 in the multiple regression model. Only cortical bone Pb
was tested, not trabecular bone Pb. Cortical bone Pb models not shown or
quantitatively described. Blood Pb rounded to nearest unit ng/dL. Mixed organic-
inorganic Pb exposure. Relatively small sample size may have prevented detection
of other significant effects. No model diagnostics described.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference,
Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
United States (cont'd)
Hu et al. (1996) 590 males (over 98% white), mean age
U.S.-Boston- around 67 yrs, divided into 146
Normative hypertensives (systolic >160 mm Hg,
Aging Study- diastolic >95 mm Hg, or daily
VA antihypertensive medication) and 444 non-
1991-1994 hypertensives. Linear blood Pb, tibia and
patella bone Pb added separately to logistic
regression model containing forced
covariates of age, race, BMI, family history
of hypertension, pack-yrs smoking, alcohol
ingestion dietary sodium and calcium. Then,
a backward elimination procedure starting
with all covariates, including all Pb
variables, resulted in a model in which only
significant covariates were retained.
Hypertensives:
Arithmetic mean (SD)
blood Pb:
6.9 ug/dL (4.3)
Mean tibia Pb:
23.7 ug/g (14.0)
Mean patella Pb:
35.1 ug/g (19.5)
Non-hypertensives:
Arithmetic mean (SD)
blood Pb:
6.1 ug/dL (4.0)
Mean tibia Pb:
20.9 ug/g (11.4)
Mean patella Pb:
31.1 ug/g (18.3)
Logistic regression model with all forced covariates revealed no significant Pb
effects when the three Pb variables were forced into the model separately. After
backward elimination, the only significant covariates left were BMI and family
history of hypertension. Of all the Pb variables, only tibia Pb remained in the
model. With each increase of 10 ug/g of tibia Pb, odds of being classified
hypertensive rose (OR = 1.21; 95% CI: 1.04, 1.43).
Stepwise regression, backward or forward, involves multiple testing with the same
data set, capitalizes on chance occurrence in the data set, and gives over-optimistic
probability values. No model diagnostic testing reported.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
Oi
Oi
United States (cont'd)
Korrick et al.
(1999)
U.S. -Boston-Nurse
Health Study
1993-1995
Morris etal. (1990)
U.S.-sampled from
general population
around Portland,
OR responding to
ads to participate in
clinical trials of
non-
pharmacological
management of
blood pressure.
1984-1989?
284 women, from 47-74 yrs, mean age
(SD) 58.7 (7.2), were divided into 97
cases (systolic 3140 mm Hg,
diastolic 390 mm Hg, or physician-
diagnosed hypertension) and
195 controls. Controls were further
classified as low normal
(<121/75 mm Hg) and high normal
>121/75 mmHg). Three ordinal
regression models were constructed,
each containing either blood Pb, tibia Pb
or patella Pb with forced entry of all
other covariates. A final backwards
elimination ordinal regression model
started with all covariates, including all
Pb variables, excluding each until only
significant variables were left.
Interactions were tested in the final
model between patella Pb and alcohol
use, age, and menopausal status.
145 males and 106 females, 73% with
arterial pressures >105 mm Hg,
provided blood pressure measurements
once a wk over four consecutive wks.
Blood for Pb analysis was collected
during this period. Stepwise multiple
regression was used to construct
separate models of systolic and diastolic
blood pressure stratified by sex.
Covariates available to be entered were
age, BMI, dietary calcium and "other
nutrient intakes," ionized serum
calcium, erythrocyte protoporphyrin and
natural log transformed blood Pb.
Mean blood Pb (SD, range):
3.1 ug/dL (2.3, <1 to 14)
Mean tibia Pb (SD, range):
13.3 ug/g (9.0, !5 to 69)
Mean patella Pb (SD, range):
17.3 ug/g(ll.l,!5to87)
Arithmetic mean (SD) blood
Pb:
Males: 8.0 ug/dL (4.4)
Females: 6.9 ug/dL (3.6)
Only patella Pb was significantly related to increased odds of hypertension
in the preliminary models, adjusted for age, BMI, alcohol, dietary calcium
and sodium, ever smoke, and family hypertension. Each 10 ug/g increase in
patella Pb was associated with increased odds of hypertension OR = 1.28
(95% CI: 1.03, 1.60). In the backward elimination model adjusted for age,
BMI dietary sodium and family hypertension, only natural log transformed
patella Pb remained in the model. Identical odds ratios from patella Pb were
obtained in both models. None of the interaction tests were significant.
Small study size may have limited power to detect significant interactions.
The proportional odds assumption of the ordinal regression model was
verified. Note that the odds ratios above are for movement from one of the
two lower categories, low normal and high normal, to the next higher
category as patella Pb increased. No other model diagnostic tests reported.
Natural log blood Pb was only a significant predictor of blood pressure in
males. Adjusting for age and ionized serum calcium, every one natural unit
increase in blood Pb was significantly associated with a 4.58 mm Hg
(neither SE nor CI stated) in systolic blood pressure and, adjusting for
hemoglobin, age, and current smoking, a 1.90 mm Hg (neither SE nor CI
stated) in diastolic blood pressure.
The usual precautions regarding multiple testing and different covariate
patterns in stratified models constructed with stepwise regression apply.
Reporting of effects not complete. Small sample size limits conclusions
about non-significant effects. High prevalence of hypertensives in sample
due to study recruitment design. Blood Pb technique, as represented by
presented graph, had a detection limit of 5 ug/dL. No model diagnostics.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description Pb Measurement
Findings, Interpretation
United States (cont'd)
Nash et al. (2003)
U.S.-NHANES III
1988-1994
1084 premenopausal and 633
postmenopausal women, from 40
to 59 yrs. Multiple linear
regression models with
covariates, including linear blood
Pb, entered as a block for systolic
and diastolic blood pressure.
Logistic regression models with
same covariates and Pb quartile
added last for hypertension.
X
Mean (range) blood Pb by
Pb quartile:
1st quartile 1.0 ug/dL
(0.5-1.6)
2nd quartile 2.1 ug/dL
(1.7-2.5)
3rd quartile 3.2 ug/dL
(2.6-3.9)
4th quartile 6.4 ug/dL
(4.0-31.1)
Linear blood Pb was entered last after forcing in age, race/ethnicity, alcohol use,
cigarette smoking, BMI, and kidney function (serum creatinine) in multiple regression
models for all women and women stratified by menopause status for systolic and
diastolic blood pressure. Pb quartile was added to logistic regression models of
hypertension (systolic 3140 mm Hg, diastolic 390 mm Hg or taking antihypertensive
medication with the same covariates as the blood pressure models, in all women and
stratified by menopausal status. Tested additional models in which women treated for
hypertension were excluded from models. All models were adjusted for sample
design and weighting.
Each increase of 1 ug/dL of blood Pb was significantly associated with a 0.32 mm Hg
(95% CI: 0.01, 0.63) increase of systolic blood pressure and a 0.25 mm Hg (95% CI:
0.07, 0.43) increase of diastolic blood pressure in all women without respect to
menopausal status. In analyses stratified by menopausal status, only postmenopausal
women showed a significant blood Pb effect. For each 1 ug/dL increase of blood Pb
was associated with significantly increased diastolic blood pressure of 0.14 (95% CI:
-0.11, 0.39 sic.) only in postmenopausal women.
Referenced to the 1 st blood Pb quartile, no other quartile showed significantly
increased odds for hypertension in all subjects or in subjects stratified by menopausal
status. With further analyses stratified by systolic and diastolic hypertension without
women taking antihypertensive medications, in the combined group of pre and
postmenopausal women the odds of diastolic hypertension were significant when the
4th Pb quartile was compared to the 1 st quartile (OR =3.4 [95% CI: 1.3,8.7]). In a
model of only postmenopausal women untreated for hypertension, odds of diastolic
hypertension were significantly increased in the higher three quartiles of blood Pb
(OR = 4.6 [95% CI: 1.1, 19.2], OR = 5.9 [95% CI: 1.5, 23.1], OR = 8.1 [95% CI:
2.6, 24.7], respectively) and odds of systolic hypertension were significant only for the
two middle Pb quartiles (OR = 3.0 [95% CI: 1.3, 6.9], OR = 2.7 [95% CI: 1.2, 6.2],
respectively).
Linear blood Pb is suspect in linear regression models of blood pressure as it is
usually associated with biased and inefficient estimation of Pb coefficients due to
probable heteroscedasticity and non-normal distribution of residuals. No model
diagnostics were reported. No statistical testing for differences in Pb coefficients
according to strata. Nine stratified models overall. Not all stated significance levels
and standard errors in the blood pressure model table corresponded for certain
variables.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description Pb Measurement
Findings, Interpretation
United States (cont'd)
Proctor et al.
(1996)
U.S.-Boston-
Normative Aging
Study (VA)
1992-1993
798 men from 17 to 44 yrs.
Multiple linear regression models
of natural log blood Pb on
systolic and diastolic blood
pressure. All covariates forced
into model.
Arithmetic mean (SD,
range) blood Pb:
6.5 ug/dL (4.0, 0.5-35)
X
oo
Natural log blood Pb, age, age-squared, BMI, adjusted dietary calcium, exercise,
indicator variables for current and former smoker, daily alcohol consumption, sitting
heart rate, and hematocrit were entered into multiple regression models without regard
for significance.
Increased diastolic, but not systolic, blood pressure was significantly associated with
increased blood Pb. Each natural log increase in blood Pb was associated with a
1.2 mm Hg (95% CI: 0.1, 2.2) increase in diastolic blood pressure.
Interactions between dietary calcium and blood Pb on blood pressure were not
significant. Further analyses stratified on use of antihypertensive medication and
those older than or equal to 74 yrs still revealed significant blood Pb-diastolic blood
pressure relationships.
Blood Pb in over half the study group (n = 410) was determined by analyzing
previously frozen erythrocytes collected several yrs prior to the blood pressure
measurements used in the study and corrected by using hematocrit values also
measured when blood was originally collected. Combining both groups means that
nearly half the group was tested for the effects of blood Pb on blood pressure
measured at the same time, the other half measured several yrs apart. There was no
correction in models for this potential effect. The effect of taking antihypertensive
medication could have been assessed in a single model by using an indicator variable.
No statistical testing for the effects of stratification on the blood Pb-blood pressure
relationship. No model diagnostics.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
United States (cont'd)
Rothenberg et al.
(1999)
U.S.-Los Angeles
1995-1998
X
vo
Rothenberg et al.
(2002a)
U.S.-Los Angeles
1995-2001
1188 immigrants and 439 nonimmigrants,
from 15 to 43 yrs, all women in 3rd
trimester of pregnancy. Multiple
regression models of natural log blood Pb
on systolic and diastolic blood pressure
with all covariates forced into models.
Covariates selected from larger set based
on significant univariate or bivariate tests.
668 women, 15 to 44 yrs, studied in 3rd
trimester pregnancy and again a mean of
10 wks postpartum. Exclusion criteria
were diabetes, renal or cardiovascular
disease, extreme postnatal obesity
(BMI >40), and subjects using stimulant
drugs. Multiple linear regression models
of natural log blood Pb, tibia and
calcaneus Pb on systolic and diastolic
blood pressure with all covariates and all
Pb variables forced into model. Separate
models for 3rd trimester and postpartum,
excluding all women with hypertension
(see below) during each specific period.
Logistic regression for hypertension
(systolic 3140 mm Hg or diastolic 390),
specific to 3rd trimester and postpartum
periods with the same covariates and Pb
variables.
Geometric mean (SD)
blood Pb:
Immigrants: 2.3 ug/dL
(1.4)
Non-immigrants:
1.9 ug/dL (1.3)
Geometric mean blood
Pb (SD):
3rd trimester:
1.9 ug/dL (1.7)
Postpartum: 2.3 ug/dL
(2.0)
Tibia mean Pb (SD):
8.0 ug/g (11.4)
Calcaneus mean Pb
(SD):
10.7 ug/g (11.9)
Natural log blood Pb, age, BMI, coffee drinking, iron supplementation, and job stress
were entered as a block without regard to significance in linear multiple regression
models of systolic and diastolic blood pressure stratified by immigration status.
Increased blood Pb was significantly associated with increased blood pressure only in
immigrants. Each natural log unit increase in blood Pb was associated with a
1.7 mm Hg (95% CI: 0.7, 2.8) increase in systolic blood pressure and a 1.5 mm Hg
(95% CI: 0.5, 1.9) increase in diastolic blood pressure in immigrants.
Used and reported model diagnostic tests, as evidenced by the use of standard error
calculations robust to residual heteroscedasticity. Stated reasons for stratification on
immigrant status were significant differences between the two groups in blood Pb,
blood pressure, age, BMI, and education. Did not statistically test difference in Pb
coefficients between the immigration strata. Did not correct for potential non-linearity
in age effects on blood pressure.
Multiple linear regression models for normotensives adjusted for postnatal
hypertension (3rd trimester model only), BMI, age, parity, smoking, alcohol,
immigrant status, and educational level plus all three Pb indices. Only calcaneus Pb
was associated with blood pressure in 3rd trimester models. Every 10 ug/g increase in
calcaneus Pb was associated with 0.70 mm Hg (95% CI: 0.04,1.36) increase in
systolic blood pressure and a 0.54 mm Hg (95% CI: 0.01,1.08) increase in diastolic
blood pressure. In postpartum models, natural log blood Pb was the only variable
statistically associated with blood pressure. Every natural log unit increase in blood
Pb was associated with 11.52 mmHg (95% CI: 12.83, 10.20) decrease in systolic
blood pressure and a -1.67 mm Hg (95% CI: 12.85, 10.50) decrease in diastolic blood
pressure.
In logistic models, only calcaneus Pb was significantly associated with increased odds
for hypertension. Each 10 ug/g increase in calcaneus Pb was associated with an OR =
1.86 (95% CI: 1.04, 3.32) of 3rd trimester hypertension. None ofthe Pb variables
was associated with postpartum hypertension.
Models did not use age-squared covariate. Models did not use repeated measures
statistics. No statistical comparisons between 3rd trimester and postpartum models.
Model diagnostic tests reported.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description Pb Measurement
Findings, Interpretation
United States (cont'd)
Schwartz et al. 543 mostly former organolead
(2000c) workers, predominantly white
U.S.-Eastern (92.8%), at a tetraethy 1/tetramethy 1
1996-1997 plant, mean (SD) [range] age 7.6 (7.6)
[41.7-73.7] yrs had blood Pb, DMSA-
chelatable Pb (4-hr, urinary Pb
excretion after a single 10 mg/kg dose
of DMSA) measured for modeling
systolic and diastolic blood pressure
and hypertension (systolic >160
^ mm Hg or diastolic 396 mm Hg or
^^. o o
C< taking antihypertensive medications.
ON Tibia Pb ~2 yrs later was also used as
^ a Pb index. For blood pressure, linear
O multiple regression with backward
elimination of non-significant
covariates or covariates that "had
important influence on the coefficients
for the Pb-dose terms." Each Pb
variable was tested in a separate
model. Potential covariates for these
models were age, BMI, current
tobacco use, and current use of
antihypertensive medications. Other
models were constructed taking out
those subjects using antihypertensive
medications. Both linear and linear +
quadratic blood and tibia Pb terms
were tested. Logistic regression
analyses were used to test the effect of
the Pb variables on hypertension,
controlling for age, diabetes, lifetime
alcohol consumption, and BMI.
Logistic models also tested each Pb
measure in interaction with age.
Blood Pb arithmetic
mean (SD, range):
4.6 ug/dL (2.6, 1
to 20)
DMSA-chelatable Pb
mean (SD, range):
19.0 ng (16.6, 1.2
to 136)
Tibia Pb mean (SD,
range): 14.4 ug/g
(9.3, ! 1.6 to 52)
Adjusting for age, BMI, current smoking, and current use of antihypertensive medications,
each 1 ug/dL increase in blood Pb-squared was significantly associated with 0.189 mm Hg
(95% CI: 0.087, 0.330) increase in systolic blood pressure with three outliers removed.
With the same covariates, each 1 ug/dL increase in linear blood Pb was significantly
associated with 0.310 mm Hg (95% CI: 0.028, 0.592) in diastolic blood pressure taken
over a 2-yr period (n = 525). No other Pb variables were significant.
For the hypertension models, only the interaction of linear blood Pb by age was significant,
with subjects showing significant decrease in odds ratio of hypertension with every joint
increase of 1 ug/dL blood Pb and 1 yr increase in age (linear blood Pb X age OR = 0.98;
[95% CI: 0.97, 0.99]). The interaction suggested a concentration-response relationship
between linear blood Pb and hypertension only up to —58 yrs of age.
Authors note that blood pressure findings "were not affected by exclusion or inclusion of
subjects using antihypertensive medications," but do not present either the data or the
statistical tests to evaluate that conclusion. No other model diagnostics were reported.
Although blood Pb was also modeled as a quadratic Pb term for systolic blood pressure, no
analysis was shown for non-linear blood Pb terms for diastolic blood pressure.
Trabecular bone Pb was not tested, though other studies indicate that it is a better Pb index
than cortical Pb for cross-sectional blood pressure and hypertension study.
Although the backward procedures described could have resulted in less than the full set of
considered covariates entering the models, all model presentations were limited to showing
the Pb coefficients and all models indicated in a footnote that the Pb coefficients were
adjusted for each possible covariate for that model. While this is possible with the short
list of covariates, given the 14 models presented one might expect to see at least one model
where one of the covariates did not remain.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
£
United States (cont'd)
Schwartz (1995)
15 prior U.S. and
European studies
published between
1985 and 1993
Schwartz (1991)
NHANES II
U.S.
1976-1980
Total subjects not specified, men and
women ages 18 to 74 yrs. Random
effects meta-analysis with inverse
variance weighting of Pb-blood
pressure coefficients from each study.
Sensitivity analysis performed by
dropping study with largest or smallest
effect.
Under 10,000 subjects (exact number
not reported), males and females, aged
25 to 74 yrs for left ventricular
hypertrophy results with logistic
regression. Linear blood Pb used for
LVH. For blood pressure results,
multiple linear regressions stratified by
sex, with one block of variables
forced, another block of variables
entered with stepwise regression, aged
6 mos to 74 yrs, exact number not
given. Natural log blood Pb used for
linear regression. Both logistic and
linear regressions adjusted for survey
design.
Blood Pb levels not
stated.
No blood Pb
descriptive data
given.
Each doubling of natural log blood Pb level was associated with an increase of 1 .25
mmHg(95%CI: 0.87, 1.63) systolic blood pressure. Sensitivity analysis showed
negligible change in meta-analysis coefficient. Concluded that adding newer studies
would not change calculated coefficient. Noted Pb-blood pressure slope was larger at
lower Pb levels than at higher Pb levels.
The study only analyzed systolic, not diastolic, blood pressure. Superseded by
Nawrot et al. (2002).
Used logistic regression to study Pb effect on left ventricular hypertrophy (LVH)
determined by a combination of electrocardiogram parameters and body habitus,
controlling for age, race, and sex. Every 10 ug/dL blood Pb increase was associated
with increased odds of LVH of 1 . 33 (95% CI: 1 .20, 1 .47). Interaction terms for race
by blood Pb and sex by blood Pb were not significant.
Blood pressure models stratified by sex always included BMI, age and age-squared,
race, and natural log blood Pb. Male blood pressure model also included family
history of hypertension, cholesterol, height, cigarette use, serum zinc, and tricep skin
fold. Female model also included serum zinc, family history of hypertension, tricep
skin fold, and cholesterol. Every 1 natural log unit of blood Pb increase was
associated with an increase in diastolic blood pressure of 2.93 mm Hg (95% CI: 0.93,
4.98) in males and 1.64 mm Hg (95% CI: 0.27, 3.01). Used interaction terms for
race-blood Pb and sex-blood Pb in a non-stratified model and found no significant
effect of race or sex on the blood Pb-blood pressure coefficient.
Incomplete reporting of subject size for models and for descriptive statistics for all
variables in models. Tested both linear and log transformed Pb in preliminary testing.
Found log Pb had lower probability values than linear Pb for blood pressure, and
linear Pb had lower probability values than log Pb for LVH. No testing of significant
difference between the two blood Pb specifications. No model diagnostics reported.
Only reported diastolic blood pressure results.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
United States (cont'd)
Sokasetal. (1997)
U.S.-Maryland
1989-1990
X
264 active or retired construction
workers, over 99% men, who were not
involved in Pb work at time of testing,
mean age (range) 43 yrs (18-79).
Multiple regression modeling of
systolic and diastolic blood pressure
adjusted for covariates of BMI, age,
hematocrit, erythrocyte
protoporphyrin, race, linear blood Pb
and a race-linear blood Pb interaction.
Method of covariate entry not made
explicit, though it appeared to be
forced.
Mean blood Pb
(range): 8.0 ng/dL
(1-30)
Linear blood Pb was not significantly related to either systolic or diastolic blood
pressure, though the race by linear blood Pb interaction was marginally significant
(p = 0.09). Each 1 ng/dL increase in blood Pb increased black systolic blood pressure
0.86 mm Hg (no SE or 95% CI reported) more than white systolic blood pressure.
Linear blood Pb term may not be appropriate. Small sample compromises
interpretation of non-significant results. By using erythrocyte protoporphyrin and
blood Pb in the same model, these two measures of Pb exposure may have been
confounded. Incomplete reporting of procedures and results. No model diagnostic
tests reported.
to Soreletal. (1991)
U.S.-NHANESII
1976-1980
2056 females, 2044 males, 473 blacks
and 3627 whites, from 18-74 yrs, were
used in survey design and weight
adjusted multiple linear regressions
stratified by sex, with separate models
for systolic and diastolic blood
pressure. Covariates included age,
BMI, race, and poverty income ratio
and linear blood Pb. Method of
covariate entry not specified but may
have been forced. Different covariate
groups were used for different models.
Primary test for the effect of race on
the Pb-blood pressure relationship was
to note the change in the race
coefficient in models with and without
the linear blood Pb variable.
Age-adjusted
arithmetic mean
blood Pb:
Black female:
13.2ng/dL(no
variance information
for any blood Pb)
White female:
12.1 ng/dL
Black male:
20.1 ng/dL
White male:
16.8
Linear blood Pb was significantly related only to diastolic blood pressure in males,
adjusting for age and BMI. For every 1 ng/dL blood Pb increase diastolic blood
pressure increased 0.13 mm Hg (95% CI: 0.04, 0.21). Adding race to the model with
and without linear blood Pb terms did not appear to change the race coefficient.
Adding poverty index to the models with and without blood Pb produced the same
small change in poverty index coefficient.
Linear blood Pb may not be appropriate. Only confidence intervals were used to
assess the significance of changes in race and poverty index coefficients across
models with and without Pb, instead of using interaction terms of these two variables
with Pb. Incomplete reporting of procedures and results. No model diagnostic tests
reported.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
United States (cont'd)
Sharp etal. (1990)
U.S.-San
Francisco, CA
1986
X
After exclusion of subjects under
treatment for hypertension, 249 male
bus drivers, 132 of whom were black,
age from 31 to 65 yrs, were used in
race stratified multiple regression
models of systolic and diastolic blood
pressure with covariate forced entry of
age, age-squared, BMI, caffeine use,
tobacco use, and natural log blood Pb.
Alcohol use was added in other
models. Other models stratified by
caffeine use.
Geometric mean (range)
blood Pb:
Black males: 6.5 ng/dL (3-21)
Non-black males:
6.2 ng/dL (2-15)
Significant log blood Pb effects were noted in blacks. In models excluding alcohol
use, for every one natural log unit increase of blood Pb, systolic blood pressure rose
7.53 mm Hg (95% CI: 0.86, 14.2) and diastolic blood pressure rose 4.72 mm Hg
(95% CI: 0.15,9.29). Stratified by infrequent/frequent caffeine users, only black
infrequent caffeine users showed a significant response to blood Pb. For every one
natural log unit increase of blood Pb, systolic blood pressure rose 16.69 mm Hg (95%
CI: 3.83,29.5) and diastolic blood pressure rose 10.43 mmHg (95% CI: 1.26, 19.6).
Non-black blood pressure was decreased with increasing natural log Pb but was
marginally significant. In all non-black subjects, for every unit increase in natural log
blood Pb, systolic blood pressure decreased -5.71 mm Hg (95% CI: -12.0, 0.6).
Addition of alcohol to the models decreased all coefficients a small amount.
Progressive addition of age, BMI, caffeine, and tobacco, in that order, progressively
increased the coefficient of natural log blood Pb in models of systolic and diastolic
blood pressure in blacks. Removal of two black outliers did not materially change the
results for blacks.
No statistical tests for comparing stratified models, models with and without caffeine
use, effect of progressive addition of covariates, or addition of alcohol. Influence
diagnostics reported for detecting the two outlying subjects. No other diagnostic tests
reported. Small differences in text and table reports of the same coefficients. Small
sample size limits interpretation of non-significant results.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
United States (cont'd)
Tepper et al. 43 females and 57 males, current or
(2001) former workers at a Pb-acid battery
U.S.-Cincinnati, factory, between 36 and 73 yrs of age,
OH with at least 10 yrs working in battery
After 1991 to production, participated. Multivariate
before 2001 regression models and logistic
regression models were constructed to
assess Pb exposure effect on outcome
(hypertension: >140/90 mm Hg and
>160/95 mm Hg or taking
antihypertensive meds; diastolic and
systolic blood pressure, and left
ventricular mass/body surface area
(g/m2). Echocardiograms were used to
determine left ventricular mass.
Variables used to adjust all models
were age, BMI, sex, and family history
of hypertension.
Plant blood Pb records were
used to calculate cumulative
blood Pb index (CBLI) used as
a tertile measure, a linear
continuous measure, and a log
transformed measure.
CBLI ug/dL-yr
1st tertile: 138-504
2nd tertile: 505-746
3rd tertile: 747-1447
Time-avgd blood Pb TABL)
was treated the same way:
TABL ug/dL
1st tertile: 12-25
2nd tertile: 26-33
3rd tertile: 34-50
No odds ratios were given for hypertension and any Pb variable for hypertension
defined as >140/90 mm Hg but ORs were claimed not significant. Odds ratios were
2.71 and 1.44 for the 3rd tertile CBLI and TABL Pb measures compared to 1st tertile,
apparently significant, but no probabilities, SEs or CIs given.
With the 81 subjects not taking anti-hypertensive meds, neither CBLI tertile nor
TABL tertile were significantly associated with either diastolic or systolic blood
pressure (coefficients, SEs or 95% CIs not given). Using log transformed CBLI
probability of a positive association with diastolic blood pressure was 0.06. Using log
transformed TABL, probability of a positive association with diastolic blood pressure
was 0.10. No coefficients, SEs, or CIs given.
Left ventricular mass adjusted for body surface area was not significantly related to
any Pb measure. No coefficients, SEs or CIs given.
Despite the certainty of the authors that "we found no convincing evidence of an
association...", the very low power of this study gives certainty to none of the
findings. Very poor reporting of results further reduces the possibility of evaluation.
No model diagnostic testing was reported.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
United States (cont'd)
Vupputuri et al. 5188 white women, 2300 black
(2003)
U.S.-NHANES III
1988-1994
X
women, 5360 white men, and 2104
black men, aged 18 yrs and older.
Survey adjusted multiple linear and
logistic regression were used to assess
linear blood Pb effect on systolic and
diastolic blood pressure and
hypertension in race and sex stratified
models.
Arithmetic mean (SD)
blood Pb:
White women 3.0 ng/dL (7.2)
Black women 3.4 ng/dL (4.8)
White men 4.4 ng/dL (7.3)
Black men 5.4 ng/dL (9.3)
Multiple linear regression models were all adjusted for age, education, BMI, alcohol
consumption, leisure time physical activity, dietary sodium and potassium, and total
calories. Only black women and men showed significant linear Pb effects. Every
1 ng/dL increase in blood Pb was associated with an increase of 0.47 mm Hg (95%
CI: 0.14, 0.80) in systolic and 0.32 mm Hg (95% CI: 0.11, 0.54) diastolic blood
pressure in black women, and 0.25 mm Hg (95% CI: 0.06, 0.44) systolic and 0.19
mm Hg (95% CI: 0.02, 0.36) diastolic blood pressure in black men.
Odds of hypertension (systolic 3140 mm Hg, diastolic 390 mm Hg, or taking
antihypertensive medication) significantly increased for every SD (3.3 ng/dL) of
blood Pb level in black women (OR = 1.39 [95% CI: 1.21, 1.61]), in white women
(OR= 1.32 [95% CI: 1.14, 1.52]), in black men (OR = 1.26 [95% CI: 0.99, 1.19]),
but not in white men.
Linear blood Pb terms are usually not appropriate in multiple linear regression models
of blood pressure. Furthermore, they reported their results in terms of change in 1 SD
unit of Pb. Linear SD of Pb is incorrect for log-normal distributions of blood Pb. No
model diagnostic tests reported. Discrepancy between Methods report of race-Pb and
sex-Pb interactions in simple, not multiple, analyses, but Results reports significant
interactions for race-Pb and sex-Pb in multiple regression models for both linear
regression and logistic regression models, without showing the results of the
interaction analyses. The probability of the stated interactions (p < 0.001) appears
extremely low, given the degree of 95% CI overlap in Pb coefficients among the
stratified models. No model diagnostics reported.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Europe
Bostetal. (1999)
Europe-England-
Health Survey for
England
1995
X
Oi
Oi
2763 women and 2563 men from a multi-
stage stratified probability survey
representative of the English population
living in private residences, mean (SE) age
for men 47.5 yrs (0.34) and for women 47.7
yrs (0.33) (all subjects 16 yrs and older)
were used in an analysis of blood Pb
association with systolic and diastolic blood
pressure. Stepwise multiple regression
analysis were used testing natural log blood
Pb against common log systolic blood
pressure and non-transformed diastolic
blood pressure, with the following potential
covariates: age, BMI, smoking status,
region of residence, social class, and
alcohol consumption. Models were
stratified by sex, with and without
adjustment for alcohol, including or
excluding those taking antihypertensive
medications.
Geometric mean blood Pb:
Men: 3.7 ug/dL (no stated
measure of variance)
Women: 2.6 ug/dL
(no stated measure of
Model tables presented only standardized variable coefficients. The most
consistent results were reported on common log Pb association with men's
diastolic blood pressure. Every doubling of blood Pb was significantly
associated with an increase of 0.78 mm Hg (95% CI: 0.01, 1.55) diastolic
blood pressure, adjusted for age, log BMI, and alcohol, but excluding men
on antihypertensive medication. Every doubling of blood Pb was
significantly associated with an increase of 0.88 mm Hg (95% CI: 0.13,
1.63) in the same model with men on antihypertensive medication. Every
doubling of blood Pb was significantly associated with an increase of 0.96
mm Hg (95% CI: 0.23, 1.70) in the same model excluding men on
antihypertensive medication and not adjusting for alcohol. Every doubling
of blood Pb was significantly associated with an increase of 1.07 mm Hg
(95% CI: 0.37, 1.78) including men taking antihypertensive medication and
not accounting for alcohol. None of the multiple regression models had
significant Pb terms for women.
This report was not sufficiently detailed. Stepwise regression modeling is
prone to the usual pitfalls. Survey design adjusted analysis not used. Pb
was not entered in models in which criterion probability was exceeded
(p>0.05). No rationale given for stratifying. No testing of differences
among Pb coefficients for the different models was made, which would have
been especially valuable to compare models adjusted and not adjusted for
alcohol use. No explanation for using log systolic blood pressure as
dependent variable. No model diagnostics reported.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Fewtrell et al.
(2004)
Global
1988-2002
X
Using available global figures on
categorized blood Pb ranges by age group,
authors calculated relative risk ratios
relating increased blood pressure to
ischemic heart disease, cerebrovascular
disease, hypertensive disease, and other
cardiac diseases. They used a calculation of
"impact fraction," based on the proportion
of the population within the particular Pb
exposure category and the relative risk at
that exposure category compared to the risk
at the reference level. They used the meta-
analysis of Schwartz (1995) to derive an
accumulating 1.25 mm Hg increase in
blood pressure in men for 5-10,10-15, and
15-20 ug/dL, and an increase of
3.75 mm Hg for blood Pb levels above
20 ug/dL. Comparable blood pressure
increases in women for each Pb category
was 0.8 mm Hg for each of the first three
categories and 2.4 mm Hg for blood Pb
>20 ng/dL.
See left for blood Pb
categories used.
The largest risk ratios were for hypertensive disease populations at ages 15-44,
calculated at 1.12, 1.41, 1.78, and 2.00 for each of the four Pb categories for
men,andl.08, 1.25, 1.45, and 1.56 for women. Risk ratios for all disease
categories increased with increasing Pb category and decreased for populations
older than 44 yrs.
The authors assumed a linear relationship between blood pressure and blood
Pb, whereas available evidence suggests it may be non-linear. If blood Pb-
blood pressure concentration-response function is log-linear, as implicitly
accepted by over half the reviewed studies, the calculated global risk ratios for
all cardiovascular disease will be overestimated at higher blood Pb levels and
underestimated at lower blood Pb levels.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Maheswaran, et al.
(1993)
Europe-England-
Birmingham
1981
X
oo
Menditto et al.
(1994)
Europe-Rome-
New Risk Factors
Survey
1989-1990
809 out of 870 workers, mean (SD)
age 43.3 (10.4) yrs, at an Pb acid
battery plant were used in the study.
Women and workers taking
antihypertensive medications were
excluded. Used multiple linear
regression analyses of systolic and
diastolic blood pressure, forcing age,
BMI, alcohol use, linear blood Pb, zinc
protoporphyrin, yrs of work exposure,
cigarette smoking as covariates.
1319 males, mean (range) age 63 (55-
75) yrs, not treated for hypertension,
were used in forward stepwise
multiple linear regression models of
systolic and diastolic blood pressure
with available covariates of age, BMI,
heart rate, serum high density
lipoprotein, non-high density
lipoprotein, triglycerides, glucose,
cigarette use, alcohol use, sum of five
skinfold thicknesses (triceps, biceps,
subscapular, suprascapular, and
suprailiac), and natural log
transformed blood Pb.
Geometric mean
(SD) blood Pb:
31.6 ng/dL (5.5)
Median (2.5th-97.5th
percentiles, range)
blood Pb: 11.3 ug/dL
(6.2-24.7, 4-44.2)
Linear blood Pb was not significant for either systolic or diastolic blood pressure.
Authors used two indices of Pb exposure in the same models. Over much of the studied
blood Pb range, zinc protoporphyrin was likely collinear with blood Pb. Linear blood Pb
may not be the appropriate metric to use in blood pressure models. Did not use age-squared
to adjust for non-linear relationship of blood pressure with age. Did not report model
diagnostics.
Only BMI, heart rate, and serum glucose were not simultaneously and significantly
correlated with both natural log blood Pb and blood pressure. In a systolic blood pressure
model adjusted for BMI, age, heart rate, high and non-high density lipoprotein, triglycerides,
glucose, and cigarettes, each unit increase in natural log blood Pb was significantly
associated with a 5.6 mm Hg (95% CI: neither SE nor CI stated) increase in blood pressure.
In a diastolic blood pressure model adjusted for BMI, heart rate, age, cigarettes, triglycerides,
and high density lipoprotein, each unit increase in natural log blood Pb was significantly
associated with a 1.7 mm Hg (95% CI: neither SE nor CI stated) increase in blood pressure.
In stratified models for alcohol drinkers (n = 1068) and non-drinkers (n = 251) only alcohol
drinkers showed significant natural log blood Pb associated blood pressure increase, with Pb
coefficients similar to those of the entire group.
Authors observed change in natural log blood Pb coefficient produced by successive addition
of covariates to models. In no case did the coefficients change by more than 30% after
addition of a covariate. Authors noted that wine was the predominant drink in alcohol users
and that the correlation between alcohol consumption and natural log blood Pb level was the
highest among all correlations reported (p < 0.001; correlation coefficient not stated).
No statistical tests were made to determine if the change in Pb coefficients with addition of
covariates was significant, nor were statistical tests made to determine if the Pb coefficients
in the alcohol use stratified models were significantly different. Small size of the non-
alcohol drinking group in stratified analysis precludes interpretation of non-significant
effects. Incomplete reporting of results. Paper published in a supplement issue reporting
meeting papers may indicate that it received less that the normal peer-review scrutiny for
published research articles. No model diagnostic tests were reported.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Mailer and
Kristensen(1992)
Europe-Denmark-
Copenhagen
County-Glostrup
Population Studies
1976-1990
X
vo
A cohort bom in 1936 was followed at
age 40 (women n = 546, men n = 504),
age 45 (women n = 430, men n = 463) and
again at age 51 (men only n = 439).
Reported no difference in results if
subjects taking antihypertensive
medications were excluded. Reported
results included these subjects. Linear
multiple regression models of systolic and
diastolic blood pressure of follow up,
stratified by sex and by yr, used a
sequence of forced entry of covariates:
natural log blood Pb was tested alone
(unadjusted), then adjusted for tobacco,
cholesterol, physical activity, and sex
(Model 1), then adjusted for the above
covariates plus systolic blood pressure
(Model 2), and then adjusted for the above
covariates plus alcohol (Model 3).
Another group of linear multiple
regression models of change of systolic
and diastolic blood pressure from age 40
to 51 yrs in men only, following the same
covariate entry scheme as above, but used
change in covariates instead of the
original covariates. All subjects were
followed until 54 yrs of age (from 1976 to
1990) to assess Pb association with total
mortality and with coronary heart disease
(CHD; ICD-8 410-414) and
cardiovascular disease (CVD; ICD-8 430-
435) combined morbidity and mortality
using Cox proportional hazards models
(n= 1050). Cox models were adjusted as
above.
Arithmetic mean (SD,
range) blood Pb by age
and sex:
Women 40 yrs:
9.6 ug/dL (3.8,4-39)
Women 45 yrs:
6.8 ug/dL (3.5,2-41)
Men 40 yrs: 13.6 ug/dL
(5.7, 5-60)
Men 45 yrs: 9.6 ug/dL
(4.3, 3-39)
Men 51 yrs: 8.3 ug/dL
(4.1,2-62)
In women, each one unit increase in natural log blood Pb was associated with a
significant increase in systolic blood pressure of 4.93 mm Hg (p = 0.002; neither SE nor
CI stated) at age 40 and an increase of 2.64 mm Hg (p = 0.06; neither SE nor CI stated)
at age 45, in models adjusted for tobacco, BMI, and physical activity (Model 1). When
alcohol (Model 2) or alcohol plus hemoglobin (Model 3) were added to the models Pb-
blood pressure relationships were not significant at either age. With each one unit
change in natural log blood Pb, diastolic pressure increased 4.26 mm Hg (p = 0.002;
neither SE nor CI stated) at 40 yrs and 3.26 mm Hg (p = 0.002; neither SE nor CI
stated) at 45 yrs in Model 1. In Model 2, the increase in diastolic blood pressure was
3.21 mm Hg (p = 0.02; neither SE nor CI stated) at 40 yrs and 2.86 mm Hg (p = 0.01;
neither SE nor CI stated) at 45 yrs. In Model 3, the increase in diastolic blood pressure
was 2.65 mm Hg (p = 0.07; neither SE nor CI stated) at 40 yrs and 2.78 mm Hg
(p = 0.01; neither SE nor CI stated) at 45 yrs.
In men, the only significant association between natural log blood Pb and blood
pressure was at 45 yrs. For every increase of one unit of natural log blood Pb the
increase in systolic blood pressure was 2.73 mm Hg (p = 0.05; neither SE nor CI
stated).
The change in blood Pb between 40 and 51 yrs was not significantly associated with
change in systolic or diastolic blood over the same period in any of the models.
None of the relative hazard ratios for CHD and DVD combined morbidity and mortality
between 40 and 54 yrs were significantly related to blood Pb concentration. Total
mortality, however, was significantly increased with increased blood Pb. In Model 1,
every increase of one natural log unit of blood Pb was associated with an increased
relative hazard of mortality of 1.96 (p = 0.009; neither SE nor CI stated). For Model 2,
every increase of one natural log unit of blood Pb was associated with an increased
relative hazard of mortality of 1.82 (p = 0.03; neither SE nor CI stated). There were 40
cases of CHD recorded, of which 13 were fatal. There were 54 cases of CVD recorded,
of which 19 were fatal. Of the total of 46 subjects who died during the period, 32
(70%) died of cardiovascular problems. It was not clear if blood Pb at a particular age
or a mean blood Pb across ages was used in the Cox proportional hazards models.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Mailer and
Kristensen(1992)
(cont'd)
X
Though this study was one of the few to use a longitudinal design, it did not
take advantage of that design feature in blood pressure modeling. Cross-
sectional multiple regression modeling at each age loses valuable information
available in repeated measures modeling. Power to detect significant effects is
much higher in repeated measurement modeling than in cross-sectional
modeling. Analyzing only change in blood pressure loses information
regarding starting and ending blood pressure. Including change in blood Pb is
problematical due to the unknown history of Pb exposure prior to the start of
the study, the resultant bone Pb load as a result of past exposure, the unknown
Pb contribution of bone to blood, and the unknown relative contributions of
past exposure and present exposure to alteration in blood pressure. Modeling
other covariates as change is also questionable. BMI, to pick a covariate with
known and strong effects on blood pressure, may be high and relatively
constant over the study period or low and relatively constant over the study. In
both cases, the change in BMI will be small, but the high BMI will be
associated with higher blood pressure than will the low BMI. Thus, both cases
modeled as change in BMI should have the same effect on blood pressure
when the high BMI subject has expected higher blood pressure than the low
BMI subject. Using difference scores for the dependent and the exposure
variables also risks confounding secular trends in either or both of these
variables, for whatever reasons, with independent difference variable effect on
dependent difference variable effect.
The Cox proportional hazards model, however, is longitudinal in nature.
Failure to detect significant associations between Pb and cardiovascular
morbidity/mortality could have been due to the small sample size used for this
type of analysis. The blood pressure part of the study did not take mortality
into account during the study, which could have produced a progressively
increasing "healthy subject" effect. Since subjects taking antihypertensive
medications were included in analyses, an indicator variable should have been
used to account for them, whether or not their exclusion in preliminary testing
produced no apparent change in results. This paper contained a good
discussion of confounding variables. Incomplete reporting of results and
procedures. No model diagnostic tests were reported.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Staessen et al.
(1996a)
Europe-Belgium-
PheeCad study.
1985-1995
X
359 men and 369 women
participated at baseline (between
1985 and 1989) and again about 5
yrs later (median 5.2 yrs) at
follow up (between 1991 and
1995), mean age (range) at
baseline 46 yrs (20-82), about
half of whom were recruited from
towns surrounding a non-ferrous
smelter (targeted to produce high
cadmium exposure) and half from
towns without heavy metal
production. Over half the men
had occupational exposure
(59.0% from the near smelter
towns, 17.4% from the other
towns).
Four different outcomes were
explored: time-integrated
conventional blood pressure (avg
of 10 baseline and 5 follow up
blood pressure measurements),
24-h ambulatory blood pressure
only during the follow up period
(avg of readings every 20 minutes
from 8 AM to 10 PM and every
45 minutes from 10 PM to 8 AM,
weighted by interval between
measurements), difference in
conventional blood pressure over
the five yr follow up period, and
incidence of developing
hypertension during follow up.
Geometric mean (5th-
95th percentile) by sex
and time period:
Baseline women:
6.6 ug/dL (3.3-14.5)
Follow up women:
4.8 ug/dL (1.7-11.8)
Baseline men:
11.4 ug/dL
(5.6-28.8)
Follow up men:
7.7 ug/dL
(3.7-20.1)
The study was one of the few prospective longitudinal studies reported and was innovative in its
use of 24-h ambulatory blood pressure as one of its outcome variables.
Time-integrated conventional blood pressure models:
In 187 peri- and post-menopausal women, after adjusting for age, BMI, gamma-
glutamyltransferase activity, and hematocrit, each increase of one unit of natural log blood Pb
was associated with an increase in diastolic blood pressure of 7.49 mm Hg (95% CI: 1.48,
13.50). No other time-integrated conventional blood pressure measurements were significantly
associated with time-integrated natural log blood Pb in either men or women, nor in stratified
groups within sex.
Ambulatory 24-h blood pressure models:
In all 345 women, after adjusting for age, hematocrit, gamma-glutamyltransferase activity, and
oral contraceptive use, each one unit increase in natural log blood Pb was associated with an
increase of diastolic blood pressure of 3.49 mm Hg (95% CI: 0.02, 6.96). When the group was
limited to the 174 premenopausal women each unit increase in natural log blood Pb was
associated with an increase of diastolic blood pressure of 5.48 mmHg (95% CI: 0.56, 10.40).
Difference in blood pressure between baseline and follow up:
After adjustment for change in BMI, beginning use of antihypertensive medication and
contraceptive medication during the follow up period, and starting smoking there was no
significant relationship between difference in either systolic or diastolic blood pressure and blood
Pb in women. After adjustment for change in BMI, change in exposure at work, change in
smoking, beginning use of antihypertensive medication in men there was no significant
relationship between difference in either systolic or diastolic blood pressure and blood Pb in
men.
Incidence of hypertension:
At baseline 107 (14.7%) and 120 (16.5%) subjects had borderline and definite hypertension,
respectively. At follow up 98 (13.5%) and 186 (25.5%) had borderline and definite
hypertension, respectively. 51 of 501 initially normotensive subjects became borderline
hypertensive and 47 of the 501 became border line hypertensive during the follow up period.
After adjusting for sex, age, and BMI, natural log baseline blood Pb was not related to significant
risk ratios of becoming hypertensive (not stated, but presumably combined definite and
borderline hypertension) or becoming a definite hypertensive.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Staessen et al.
(1996a) (cont'd)
X
to
Multiple regression models were used to test the
association between natural log transformed
blood Pb (mean of baseline and follow up Pb)
and blood pressure (systolic and diastolic),
stratified by sex, then further stratified by use of
antihypertensive medications in men and
menopausal status in women. Age and age-
squared (calculated in quintiles) were forced into
the models, then remaining covariates were
stepwise added to the model. Though not
explicitly stated, natural log blood Pb (mean of
baseline and follow up) was likely forced in last.
Other candidate covariates were BMI,
hemoglobin or hematocrit, serum gamma-
glutamyltransferase activity (an index of alcohol
use) and serum calcium, 24 h urinary sodium and
potassium excretion, energy expenditure,
exposure to heavy metals (at the workplace),
social class, smoking and drinking habits,
menstrual status in women, and use of
antihypertensive medications, oral contraceptives,
and hormone replacement therapy. In ambulatory
blood pressure models, differences between
baseline and follow up blood pressure models
were constructed in the same way. For the
difference models "concurrent variations in blood
Pb concentrations" were used, presumably
difference in baseline and blood Pb.
The study does not use the full power of repeated measurements in the
analyses. For problems encountered when collapsing repeated
measurements to difference measures, see Mailer (1992) above. Stepwise
regressions are prone to capitalizing on chance results due to multiple
testing of the same data and almost always produce a different mix of
covariates when they are stratified. Thus, it was puzzling to find that where
information on the effects of stepwise covariate addition to models was
available in this article, that the same covariates were listed for both models
based on the stratification variable. There is excessive reliance on
fractionation of the data set due to multiple stratification, sometimes
reducing the number of subjects in a model to as few as 171. Even the
models using the most subjects had only 359 subjects. Low power to detect
significant effects cautions against any interpretation of non-significant
results. The time-integrated model used 10 baseline blood pressure
measurements and 5 follow up blood pressure measurements, thus
weighting the avg toward baseline blood pressure. The entry of the
biochemical correlate of alcohol use in most of the models suggests that Pb
effects and Pb-containing alcohol effects on blood pressure were confused,
especially given the European setting and the time period during which the
study was conducted. Control for use of hypertensive medication rarely
entered models and partial control for this variable was achieved only by
stratified analyses, further reducing power to detect significant effects in the
remaining subgroup. No justification was given for stratified analyses.
Incomplete information in statistical methods and results complicates
interpretation. It was uncertain if stepwise regression was used for logistic
models. No comparisons were performed to assess possible bias due to
subject attrition over the course of the study.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Staessen et al.
(1996a) (cont'd)
For the hypertension incidence model two
definitions of hypertension were used:
definite hypertension (systolic >160 mm Hg,
diastolic >95 mm Hg or taking
antihypertensive medications) and borderline
hypertension (systolic between 141 to
159 mm Hg and diastolic between 91 to
94 mm Hg). Method of covariate entry into
hypertension incidence models not stated.
Baseline natural log blood Pb was used as the
exposure index.
The over six decades of age represented in the sample was modeled by linear and
quadratic terms based on age quintiles rather than continuous age, making it likely
that adequate control for age effects on blood pressure was not achieved and that
the "healthy subject" effect seen in older groups was not controlled. If stepwise
addition of significant covariates was used in the blood pressure difference models,
were covariates in those models that were marked in the coefficient column as
non-significant not included in the models, and if that were so, it is unclear from
where the probability values that substitute for the coefficients of those variables
were derived. There were no model diagnostic tests reported.
X
Staessen et al.
(1993)
Belgium-Cadmibel
Study
1985-1989
827 males and 821 females recruited from two
areas in Belgium, one of them surrounding a
non-ferrous smelter, mean age (SD) 46 (15)
and 44 (15) yrs, in men and women
respectively. Subjects taking antihypertensive
medication were excluded from the analyses.
Stepwise multiple regression models of
systolic and diastolic blood pressure were
stratified by sex. Covariates available for
entry were age and age-squared, BMI, pulse
rate, log protoporphyrin, log gamma-
glutamyltranspeptidase, serum calcium, log
serum ferritin, log serum creatinine, log serum
zinc, urinary calcium, urinary sodium, and
urinary potassium. Natural log blood Pb was
the only variable forced into the models.
Additional models tested the interaction of
serum calcium and blood Pb on blood
pressure.
Geometric mean
blood Pb (range),
stratified by sex:
Male blood Pb:
10.4 ug/dL
(2.7, 84.9)
Female blood Pb:
6.2 ug/dL (1.3, 42.4)
In men, adjusting for age and age-squared, BMI, pulse rate, log gamma-
glutamyltranspeptidase, serum calcium, and log serum creatinine, every unit
natural log blood Pb increase was significantly associated with a -5.2 mm Hg (95%
CI: !0.5, 19.9) decrease in systolic blood pressure. Natural log blood Pb was not
significant in the model for diastolic blood pressure for men nor the systolic or
diastolic blood pressure for women.
Adjusting for age and age-squared, BMI, pulse rate, and log gamma-
glutamyltranspeptidase, the interaction term between natural log blood Pb and
serum calcium was only significant for systolic blood pressure in women. Every
doubling of blood Pb was associated with a 1.0 mm Hg decrease in systolic blood
pressure at serum calcium concentration of 2.31 mmol/L (25th percentile) and an
increase in systolic blood pressure of 1.5 mm Hg at serum calcium concentration
of 2.42 mmol/L (75th percentile).
Stepwise multiple regression analyses run risks of accepting chance associations
due to multiple analyses of the same data set. The role of alcohol use or alcohol
use markers in confounding Pb effect on blood pressure in this setting has already
been noted. The unexplained interaction between serum calcium and blood Pb
highlights the potential confounding role of serum calcium with Pb in blood
pressure studies. The study shows graphs indicating distinct differences in the age-
serum calcium and age-blood Pb relationships for men and women. From 50-70
yrs of age serum calcium is higher than from < 29-49 yrs in women and
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Staessen et al.
(1993) (cont'd)
X
exceeds serum calcium of men at those older ages. The steepest rise in
women's blood Pb with age occurs between the 40-49 and 50-59 yr decades.
The timing of these changes in women suggests that menopause may be a
factor, which was accounted for only in the model for diastolic blood pressure.
It also suggests that serum calcium level and age were also confounded in the
blood pressure models. As serum creatinine clearance and blood Pb are
inversely related, and serum creatinine is a significant covariate in the systolic
blood pressure model for men with a significant negative blood Pb coefficient,
it is possible that serum creatinine and blood Pb are confounded with blood
pressure in the men's systolic blood pressure model. There were no
assessments of subject selection bias due to exclusions. The authors note
examining quintile blood pressure relationships with all covariates to determine
the acceptability of the linear relationship implied by the linear modeling
technique. No other model diagnostic tests were reported.
Telisman et al. 100 workers from factories producing Pb-
(2004) based products, mean (range) age 30 (20-43)
Europe-Croatia- yrs. Exclusion criteria were absence of
Zagreb psychological stress (e.g., death in family)
Date of data over last 4 mos, absence of verified diabetes,
collection not coronary heart disease, cerebrovascular and
given. peripheral vascular disease, renal disease,
hyperthyroidism, androgenital syndrome,
primary aldosteronism, and "other diseases
that could influence blood pressure or metal
metabolism." Linear or natural log blood Pb
were considered for stepwise entry in models
of systolic and diastolic blood pressure,
forcing in all other covariates: blood
cadmium, BMI, age, serum zinc, serum
copper, hematocrit, smoking, and alcohol.
Arithmetic mean
(range) blood Pb:
36.7 ug/dL
(9.9-65.9)
Neither linear nor natural log blood Pb entered as significant in multiple
regression models of systolic and diastolic blood pressure.
Very small sample size limited power to detect significant effects; non-
significant effects should not be interpreted as lack of effect. Too many
covariates for a small study. Almost no subjects below 10 ug/dL. Taking
hypertensive medications not controlled, likely a problem with top systolic and
diastolic blood pressure in the group 170 mm Hg and 110 mm Hg, respectively.
No model diagnostic testing reported.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Asia
Lee etal. (2001)
Korea-Chonan
1997-1999
X
798 workers from various Pb-using or
producing factories, mean (SD, range) age 40.5
yrs (10.1) [17.8-64.8], 79.4% male, were
classified as to Vitamin D receptor genotype
(VDR bb or Bb/BB) and delta-aminolevulinic
acid dehydratase (ALAD11 or 12) genotype, as
VDR polymorphism has been implicated in
modifications of Pb absorption and Pb uptake
and release from bone as well as risk for
elevated blood pressure and hypertension, and
ALAD polymorphism affects Pb binding to it in
the erythrocyte, the major storage depot of Pb in
blood. The hypothesis was that polymorphism
type could influence the effect of Pb on blood
pressure and hypertension.
Multiple linear regression models of linear
blood Pb, DMSA-chelatable Pb, and tibia Pb
effect on systolic and diastolic blood pressure
with potential covariates of age and age-
squared, sex, creatinine clearance, hemoglobin,
weight, height, BMI, job duration, tobacco and
alcohol consumption, pack-yrs of tobacco, and
cumulative life time alcoholic drinks. Stepwise
procedure allowed retention of covariates only
if they were significant or "there were
substantive changes in the coefficients of
predictor variables after" their inclusion. In the
models shown, Appearance of multiple Pb
variables and the interaction between Pb
variables and genotype for each gene depended
upon the specific model. Both ALAD and VDR
receptor polymorphism were sometimes tested
simultaneously in each model containing
polymorphism terms and sometimes VDR
appeared without ALAD.
Arithmetic mean
(SD, range) blood
Pb: 32.0 ug/dL
(15.0,4-86)
Mean (SD, range)
DMSA-chelatable
Pb: 186 ug
(208.4,4.8-2103)
Mean (SD, range)
tibia Pb: 37.2 ug/g
(40.4, !7to338)
With simple t-tests, subjects with VDR Bb/BB allele were significantly older,
had more DMSA-chelatable Pb, and had higher systolic and diastolic blood
pressure than subjects with VDR bb allele.
In multiple regression models of systolic blood pressure, controlling for age
and age-squared, sex, BMI, antihypertensive medication use, and cumulative
life-time alcoholic drinks, adding tibia Pb, VDR type, and ALAD type, each
increase of 10 ug/g of tibia Pb was associated with an increase of 0.24 mm Hg
(95% CI: -0.01, 0.49) and VDR BB/Bb type was associated with an increase
of 3.24 mm Hg (95% CI: 0.18, 6.30) blood pressure compared to the VDR bb
type. ALAD genotype was not significant. In the same model, but
substituting linear blood Pb for tibia Pb, each increase in 1 ug/dL of linear
blood Pb was associated with an increase of 0.07 mm Hg (95% CI: 0.00,
0.14) and VDR BB/Bb type was associated with an increase of 2.86 mm Hg
(95% CI: !0.22, 5.94) blood pressure compared to the VDR bb type. ALAD
genotype had no significant effects on blood pressure.
When both tibia and linear blood Pb were entered simultaneously along with
VDR genotype, adjusting for the same covariates, only VDR Bb/BB was
significant; compared to VDR bb, blood pressure was 3.51 mm Hg (95% CI:
2.41, 8.61) higher. ALAD genotype had no significant effects on blood
pressure.
In a model without any Pb terms, VDR genotype was interacted with the age
and the age-squared terms. The VDR Bb/BB genotype interaction with the
linear age term was significant for systolic blood pressure. Compared with
the bb genotype the VDR Bb/BB genotypes' blood pressure increased
0.36 mm Hg (95% CI: 0.06, 0.66) per yr faster with increasing age.
There were no significant effects of any Pb variable with diastolic blood
pressure, though the VDR Bb/BB genotype had significantly higher blood
pressure (1.9 mm Hg; not enough information given to calculate CI) than the
bb genotypes.
There were no significant interactions of the Pb measures with the genotypes
for either ALAD or VDR.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Lee etal. (2001)
(cont'd)
X
Oi
Oi
Lustberg et al.
(2004)
Korea-Chonan
1997-1999 (period
of enrollment; no
statement on dates
of data collection)
Logistic regression analysis was used to test
the effect of the Pb indices on hypertension
(systolic >160 mm Hg or diastolic
>96 mm Hg or taking antihypertensive
medications) using the same group of
potential covariates, testing the Pb terms
and the Pb-genotype interaction terms
separately. The hypertension models tested
both gene polymorphisms separately.
793 (number given for genotype analysis;
numbers in models not given) current and
former Pb workers, mean (SD) age 40 (10)
yrs and 80% male, were genotyped for the
three polymorphisms of endothelial nitric
oxide synthase (eNOS) (GG, GT, TT), an
enzyme that is a modulator of vascular
resistance. The effect of genotype and the
interaction of genotype with blood Pb and
tibia Pb on systolic and diastolic blood
pressure were evaluated by multiple linear
regression analyses, forcing covariates of
age (modeled as a 2 degree of freedom
spline with knot at 45 yrs), sex, natural log
BMI, smoking and alcohol consumption,
high school education, and job duration.
Both blood Pb and tibia Pb were entered as
percentiles and entered together. Logistic
models of hypertension (systolic
3140 mm Hg or diastolic 390 mm Hg or
reported use of antihypertensive
medication) used the same covariates.
Interaction terms between each of the Pb
measures (plus a Pb-squared term) and
genotype was used to determine differential
effect of Pb according to genotype.
Pb according to
genotype:
Arithmetic mean
(SD) blood Pb, GG:
32 (15) ug/dL
Arithmetic mean
(SD) blood Pb,
TG/TT: 32
(15) ug/dL
Mean (SD) tibia Pb,
GG: 37(42)ng/g
Mean (SD) tibia Pb,
TC/TT: 36(34)ng/g
Subjects with the Bb/BB genotypes had a significantly higher odds hypertension
prevalence (OR = 2.1 [95% CI: 1.0, 4.4]) than subjects with the bb genotype,
adjusting for age, sex, BMI, tibia Pb, and current alcohol use. There were no
significant effects of any Pb variable nor of ALAD on hypertension status.
Linear blood Pb may not give efficient and unbiased estimates of blood Pb effect on
blood pressure. The descriptive data shows highly skewed distributions for blood Pb,
DMSA-chelatable Pb, and tibia Pb in this group, suggesting that coefficients of all Pb
effect on blood pressure may not have been efficient and unbiased. Stepwise models
usually produce different covariate patterns for different models, though the tables
indicate that the covariates used for all the models discussed above were the same. No
model diagnostic tests were reported.
85% (673/793) of the group were typed GG, 14% (114/793) were TG, and 1% (6/793)
were TT. TG and TT groups were combined for analysis (TG/TT).
Mean systolic and diastolic blood pressures, adjusted for all covariates, were not
significantly different between GG and TG/TT groups.
In multiple regression models for systolic and diastolic blood pressure, neither
percentile blood Pb nor percentile tibia Pb, entered together, were significant
predictors. Interaction terms between the Pb variables and genotype were not
significant.
In the logistic regression model for hypertension, neither percentile blood Pb nor
percentile tibia Pb, entered together, were significant predictors.
Reporting was incomplete: number of subjects entering the models was not stated; no
comparisons between recruited subjects and subjects not used in models. Despite
reporting non-significant interactions, the paper showed both loess plots and tables of
analyses stratified by genotype, reporting significant associations between both tibia
and blood Pb in the GG genotype, insignificant in the other. Inspection of the loess
plots revealed striking non-linearity for both adjusted blood Pb-systolic blood pressure
and adjusted tibia Pb-systolic blood pressure relationships. Small group size of the
TG/TT genotypes and highly unbalanced terms of the interaction may have
contributed to the non-significant interactions. Although the interaction Pb term was
also probed as a quadratic function, the tibia Pb interaction was not, suggesting that
poor concentration-response specification in the model may also have contributed to
the lack of significant main effects and interactions.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Nomiyama et al.
(2002)
China, Beijing
No statement on
dates of data
collection
X
123 female Pb-exposed leaded crystal toy
workers, mean age (range) 27.3 (17-44) yrs,
and 70 female sewing workers (reference
group), mean age (range) 24.2 (16-58) yrs
were tested. Forward stepwise multiple
regression models of systolic and diastolic
blood pressure of the combined groups
were used with linear blood Pb and a set of
covariates. Variables with p < 0.2 were
allowed to enter. The covariate set was
selected from a larger set of potential
covariates by factor analysis, and a
representative variable from each factor
was selected for possible entry in the
regressions.
Alternate models were constructed using
four ordered categories of blood Pb, instead
of the linear continuous blood Pb variable.
Logistic regressions were used to determine
the odds of elevated systolic (3125 mm Hg)
and elevated diastolic (380 mm Hg) blood
pressure as a function of blood Pb category.
Blood Pb mean
(SD, range) in Pb
workers: 55.4
(13.5,22.5-
99.4 ng/dL
Blood Pb mean
(SD, range) in non-
Pb workers:
6.4(1.6,3.8-
11.4)ng/dL
Adjusted for age, urine protein, and plasma triglyceride, each 1 |ig/dL increase in
linear blood Pb significantly associated with a 0.13 mm Hg increase in systolic
blood pressure (no SE or CI given; p = 0.0003). Adjusted for plasma triglyceride,
age, urine protein, plasma low density lipoprotein, and hypertension heredity, each
1 ng/dL increase in linear blood Pb was associated with a 0.10 mm Hg increase in
diastolic blood pressure (no SE or CI given; p = 0.0001).
Using the ordered categories of blood Pb and the same covariates for systolic and
diastolic blood pressure, the 40-60 ng/dL group had 4.2 mm Hg (95% CI: 0.0, 8.5)
higher systolic blood pressure and 4.1 mm Hg (95% CI: 1.3, 6.8) higher diastolic
blood pressure than the reference group (blood Pb (<11.4 ng/dL). The group with
360 ng/dL blood Pb had 7.5 mm Hg (95% CI: 3.0, 12.0) systolic blood pressure and
6.3 mmHg (95% CI: 3.4, 9.1) diastolic blood pressure higher than the reference
group.
Logistic regression models for "elevated" blood pressure, modeled using the same
covariates were similar. In the 40-60 ng/dL group odds of systolic blood pressure
3125 mm Hg and diastolic blood pressure 380 mm Hg were 4.26 (95% CI: 1.07,
17.04) and 2.43 (95% CI: 0.97, 6.04), respectively, higher than the reference group.
The odds of "elevated" systolic and diastolic blood pressure in the group with blood
Pb 360 ng/dL were 7.48 (95% CI: 1.86, 30.12) and 3.31 (95% CI: 1.29, 8.50),
respectively.
Incomplete reporting in paper: no model N, no SEs for linear blood Pb regressions,
no description of type of factor analysis used or dates of data collection. Innovative
use of factor analysis to select covariates that, depending on how the factor analysis
was run, could have produced a set of orthogonal variables for model entry.
However, BMI was not included in the original set of covariates or in the models.
Small sample size limits conclusions based on nonsignificant results. Stepwise
regression produced a different covariate pattern for each component of blood
pressure. The linear blood Pb variable may be inappropriate given the marked
skewness of blood Pb in descriptive analysis. The 11 ng/dL gap in blood Pb
between Pb workers and non-Pb workers could have introduced problems in
analyses with continuous blood Pb. Larger age spread in non-exposed group than in
exposed group could have caused misspecification of age variable. No control for
antihypertensive medication use. No model diagnostics reported.
-------
Table AX6-5.1 (cont'd). Effects of Lead on Blood Pressure and Hypertension
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
oo
Asia (cont'd)
Wuetal. (1996)
Central Taiwan
No statement on
dates of data
collection
222 workers in two Pb battery plants, 112
men, mean (range) age 36.2 (18-67) yrs, and
110 women, mean (range) age 36.2 (18-71)
yrs were tested for blood Pb relationships
with systolic and diastolic blood pressure in
multiple regression models, using a fixed,
forced set of covariates: age, sex, BMI,
working history, yrs of work, noise exposure,
natural log ambient air Pb concentration, and
ordered categorical blood Pb concentration.
Arithmetic mean (SD,
range) blood Pb:
Women: 44.6(18.4,
8.3-103.l)ng/dL
Men: 60.2(26.8,
17.0-150.4) ug/dL
Using four ordered blood Pb categories (<25 ug/dL [n = 16/222; 6.8%], 25-
40 ug/dL [58/222; 26.1%], 41-60 ug/dL [63/222; 27.9%], and>60 ug/dL
[85/222; 38.3%]) adjusted systolic and diastolic blood pressure were not
significantly related to the top three blood Pb categories compared to the
lowest, natural log ambient Pb. Yrs in work environment was a significant
predictor of both systolic and diastolic blood pressure, but age was only
marginally significant for systolic blood pressure and not significant for
diastolic blood pressure.
Small study size limits any conclusions drawn from non-significant results.
Three measures, all related to Pb exposure, were simultaneously tested in the
models. While blood Pb may only be weakly correlated with yrs of work,
ambient air Pb would be expected to be much better correlated with blood Pb.
There is a clear possibility of collinearity among those three variables, which
would inflate standard errors and reduce coefficients. Authors selected
ordered categories of Pb to "avoid unnecessary assumption of linearity." The
use of natural log air Pb concentration suggests that some diagnostics were
run, but no model diagnostic tests were reported. No control for
antihypertensive medication use.
-------
Table AX6-5.2. Effects of Lead on Cardiovascular Morbidity
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
United States
X
Cheng et al.
(1998)
U.S.-Boston,
Normative Aging
Study (VA)
1991-1995
Gump et al. (2005)
U.S.-Oswego,NY
Dates of study not
775 males (97% white), mean age (SD,
range) 67.8 yrs (7.3, 48-93).
Multiple linear regression models of
heart rate-corrected QT and QRS
electrocardiogram intervals were
adjusted by stepwise entry of
covariates, retaining only those that
remained significant at p < 0.10.
Linear blood Pb, tibia, and patella bone
Pb were apparently (not described in
text) entered separately. Logistic
regression models for Minnesota ECG
Coding Center diagnoses of
intraventricular conduction deficit
(IVCD), atrioventricular conduction
deficit (AVCD), and arrhythmia were
adjusted by covariates the same way.
Only analyses stratified by age (<65
yrs, n = 277; 365 yrs, n = 498) were
presented
See Gump et al. (2005) entry in Blood
Pressure and Hypertension section for
heart rate, stroke volume, cardiac
output, total peripheral resistance, and
cardiac interbeat interval data.
Arithmetic mean (SD)
blood Pb: 5.8 ug/dL (3.4)
Mean (SD) tibia Pb:
22.2 ug/g (13.4)
Mean (SD) patella Pb:
30.8 ug/g (19.2)
Multiple regression models of QT intervals, adjusted for age, alcohol intake,
BMI, and diastolic blood pressure, found that only tibia and patella Pb were
significantly related to outcome in the under 65 group. Every 10 ug/g increase of
tibia and patella Pb was associated with a 5.0 ms (95% CI: 0.8, 9.2) and 3.0 ms
(95% CI: 0.2, 5.8) increase in QT interval, respectively. Multiple regression
models of QRS intervals, adjusted for age, fasting glucose level, and diastolic
blood pressure, also found that only tibia and patella Pb were significantly related
to outcome in the under 65 group. Every 10 ug/g increase of tibia and patella Pb
was associated with a 4.8 ms (95% CI: 1.8, 7.8) and 2.2 ms (95% CI: 0.1, 4.4)
increase in QRS interval, respectively. There were no significant effects of Pb in
the 65 and over group.
Logistic regression models of IVCD, adjusted for age and serum HDL level,
found that only tibia Pb was significantly related to outcome in the under
65 group. Every 10 ug/g increase of tibia Pb was associated with increased odds
of IVCD, OR = 2.23 (95% CI: 1.28, 3.90). There were no significant Pb effects
in the 65 and over group for IVCD. Logistic regression models of AVCD,
adjusted for age and serum HDL level, found that both tibia and patella Pb were
significantly related to outcome in the 65 and over group. Every 10 ug/g
increase of tibia Pb and patella Pb was associated with increased odds of AVCD,
OR= 1.22(95%CI: 1.02, 1.47) and OR = 1.14 (95% CI: 1.00,1.29),
respectively. Pb was not significantly related to AVCD in the under 65 group.
There were no significant effects of Pb on arrhythmia in either age group.
Stepwise models may capitalize on chance associations. Linear blood Pb
specification may not be appropriate in some or all of these models. Not clear if
three models were constructed for each stratified analysis for each outcome, each
based on a different Pb index. No statistical comparisons across strata. No
model diagnostics were presented.
-------
Table AX6-5.2 (cont'd). Effects of Lead on Cardiovascular Morbidity
Reference, Study
Location, and
Period Study Description
Pb Measurement
Findings, Interpretation
United States (cont'd)
X
Oi
Oi
O
Navas-Acien
(2004)
U.S.-NHANES
IV-Phase 1
1999-2000
Schwartz (1991)
NHANESII
U.S.
1976-1980
2125 subjects (1070 males, 1055
females), age 40->70 yrs were tested
for peripheral arterial disease (PAD;
n = 139) by taking the ratio of the
ankle mean systolic blood pressure to
the arm mean systolic blood pressure.
Any subject with the ratio <0.90 was
classified as PAD. Logistic regression
analysis was weighted and adjusted by
sample design. Covariates forced into
the models were age, sex, race,
education, and Pb quartile (Model 1);
Model 1 covariates plus BMI, alcohol
intake, hypertension, diabetes,
hypercholesterolemia, glomerular
filtration rate, and C-reactive protein
(Model 2); Model 2 covariates plus
self-reported smoking status and serum
cotinine (Model 3); and Model 3
covariates plus cadmium quartile
(Model 4). Tested interactions
between Pb and cadmium on PAD,
and between Pb and sex, race, smoking
status, renal function, and c-reactive
protein on PAD. Tested for trend of
OR as a function of Pb quartile.
See Schwartz (1991) entry in Blood
Pressure and Hypertension for left
ventricular hypertrophy results.
Geometric mean blood Pb
(25th-75th percentile):
2.1 ug/dL (1.4, 2.9)
Pb quartile 1: <1.4 ug/dL
Pb quartile 2:
1.4-2.1 ug/dL
Pb quartile 3:
2.1-2.9 ug/dL
Pb quartile 4: >2.9 ug/dL
Odds for PAD significantly increased with Pb quartile (1st quartile used as
comparison) for all four models. Only models 1 and 2, however, showed a
significant increase in odds of PAD for the 4th Pb quartile compared to the 1 st Pb
quartile, OR = 3.78 (95% CI: 1.08, 13.19) and OR = 4.07 (95% CI: 1.21,13.73).
None of the tested interactions with blood Pb quartile were significant.
Well-designed study with sound statistical analysis. Including two variables for
smoking in Models 3 and 4 (smoking status and cotinine) may have over-
controlled for smoking). There was a trend toward increased blood Pb level with
increased smoking status and with increased cotinine levels, though no statistical
tests of trend were reported. Thus the two smoking variables and Pb may have
been confounded with PAD. No model diagnostic tests reported.
-------
Table AX6-5.2 (cont'd). Effects of Lead on Cardiovascular Morbidity
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
United States (cont'd)
Tepper et al.
(2001)
U.S.-Cincinnati,
OH
After 1991 to
before 2001
See Tepper et al. (2001) entry in Blood
Pressure and Hypertension for left
ventricular mass results.
X
Oi
Oi
Europe
Gustavsson et al.
(2001)
Europe-
Stockholm,
Sweden
1992-1994
Study base was all Swedish citizens
45-70 yrs old from Stockholm County
free of previous myocardial infarction.
Cases who survived at least 28 days
after infarct (1,105 males and 538
females) of which 937 men (85%) and
398 women (74%) had sufficient
information on occupational exposures
and "main confounders", were
compared against referents (1,120 men
and 538 women) matched to cases by
sex, age, yr, and hospital catchment
area. Risk ratios for the case group
compared to referent group were
adjusted on the basis of the matching
variables and smoking, alcohol
drinking, hypertension, overweight,
diabetes mellitus, leisure physical
"inactivity", and were calculated for a
number of exposure factors separately,
including Pb.
Pb exposure was
classified as none, low or
high corresponding to
airborne dust levels of 0,
>0 to 0.03, and
30.04 mg/m3,
respectively, for the
highest intensity of
exposure during at least
one yr of work. The same
three classifications were
used for 0, >0 to 0.04, and
30.05 mg/m3 for
cumulative exposure.
All risk ratios were calculated relative to the "no exposure" groups. Adjusted
risk ratios for surviving a myocardial infarction were 0.88 (95% CI: 0.69,1.12)
and 1.03 (95% CI: 0.64, 1.65) for low and high exposure groups for peak Pb
exposure, and were 0.81 (95% CI: 0.60, 1.11) and 1.00 (0.74, 1.34) for the low
and high cumulative exposure groups.
This study of myocardial morbidity was compromised by poor Pb exposure
characterization (occupational air dust Pb concentration) and by including a
covariate collinear with Pb exposure and confounded with the outcome,
hypertension, in the adjusted models.
No model diagnostics were reported.
-------
Table AX6-5.3. Effects of Lead on Cardiovascular Mortality
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
Oi
Oi
to
United States
Lustberg and
Silbergeld (2002)
U.S.-NHANESII
1976-1980,
follow up to 1992
Schober et al.
(2006)
U.S.-NHANES
III
1988-1994,
follow up to 2000
4190 persons, 30 to 74 yrs, 929 of whom
died during follow up, had baseline blood Pb
measurements during the NHANES II
period. Proportional hazard models for
circulatory disease-related death (ICD-9
codes 390-459) were based on the complex
survey design, but not weighted. Presented
models were unadjusted, adjusted for age
and sex, and adjusted for age, sex, location,
education, race, income, smoking, BMI, and
exercise. Blood Pb was entered as an
ordinal three-category variable.
9757 persons, age 40 yrs, 2515 of whom
died during follow-up (median length of
follow-up 8.55 yrs), had baseline blood Pb
measurements during the NHANES III
period. Analyses were performed using
proportional hazard models for all cause
deaths, major cardiovascular disease-related
deaths (100-178), and malignant neoplasms
(COO-C97). Multivariate models were
adjusted for sex, race/ethnicity, education,
and smoking status and stratified by age.
Blood Pb was entered as an ordinal three-
category variable.
Blood Pb<10|ig/dL,
n=818
Blood Pb 10-19 ng/dL,
n = 2735
Blood Pb 20-29 ng/dL,
n=637
Blood Pb 330 |ig/dL,
n = 102, excluded from
analysis
Blood Pb <5 ng/dL
(median 2.6 ng/dL),
n = 6608
Blood Pb 5-9 ng/dL
(median 6.3 ng/dL),
n = 2532
Blood PblOjjg/dL
(median 11.8 (ig/dL),
n=617
Crude, sex and age adjusted, and multivariate adjusted circulatory disease
mortality were all significantly increased in the 20-29 ng/dL group compared
to the <10 ng/dL reference group. Risk ratio for the highest Pb group for
crude circulatory mortality was 1.74 (95% CI: 1.25, 2.40), for age and sex
adjusted circulatory mortality was 1.48 (95% CI: 1.10, 2.01), and for
multivariate circulatory mortality was 1.39 (95% CI: 1.01, 1.91).
Stratified analyses were performed by race, sex, age, smoking, education, etc.,
but only for all-cause mortality. No model diagnostics reported.
Multivariate-adjusted cardiovascular disease mortality was significantly
increased in the 10 ng/dL group compared to the <5 ng/dL reference group.
All cause and cancer mortalities were significantly increased in the 5-9 ng/d
and 10 ng/dL groups.
Relative risk for cardiovascular disease mortality, compared to <5 ng/dL:
5-9ng/dL: 1.20 (95% CI: 0.93,1.55)
10ng/dL: 1.55 (95% CI: 1.16,2.07)
Relative risk for all cause mortality, compared to <5 ng/dL:
5-9ng/dL: 1.24 (95% CI: 1.05,1.48)
10ng/dL: 1.59 (95% CI: 1.28,1.98)
Relative risk for cancer mortality, compared to <5 ng/dL:
5-9ng/dL: 1.44 (95% CI: 1.12,1.86)
10ng/dL: 1.69 (95% CI: 1.14,2.52)
Tests for trends were statistically significant for all three mortality groups.
-------
Table AX6-5.3 (cont'd). Effects of Lead on Cardiovascular Mortality
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
ON
ON
United States (cont'd)
Michaels et al. 1261 males, avg age (range) at the
(1991) beginning of study 49.6 yrs (19-83),
U.S.-New York representing 24,473 person-yrs were
City followed. 498 died in the interval.
1961-1984 Subjects belonged to the International
Typographical Union and worked at two
large city newspapers. Hot Pb linotyping
was discontinued at the newspapers
during 1974-1978, providing the primary
source of occupational exposure. Last
exposure for all subjects still employed
was at the end of 1976.
Standardized mortality ratios (SMR)
were calculated using the LTAS program
developed by NIOSH, calculating the
expected number of deaths of the cohort
referenced to a comparison population, in
this case disease-specific mortality rates
from New York City. Cohort was
stratified based on yrs of employment.
Causes of death were based on ICD-8
codes.
Exposure was estimated
based on yrs of linotype
employment before the
end of 1976. Authors
note that, based on
measurements at other
print shops using hot Pb
linotype, air Pb levels
probably did not exceed
20 ug/m .
Standardized mortality ratio was significant (SMR = 1.68 [95% CI: 1.18, 2.31])
only for cerebrovascular disease in those working, and thus exposed, for 30 yrs
or more. Neither arteriosclerotic heart disease (ICD-8 410-414) nor vascular
lesions of the central nervous system (ICD-8 430-438) had significant SMR in
the total cohort not stratified by yrs of exposure.
No direct measurement of Pb exposure. Many groupings of ICD codes were
explored in stratified and unstratified analyses, with the only significantly
elevated SMR found for cerebrovascular disease. No a priori hypotheses.
General weakness of all studies relying on a comparison population is that the
cohort belongs to the comparison population and can influence the comparison
mortality rates in direct proportion to the ratio between cohort and comparison
population size.
-------
Table AX6-5.3 (cont'd). Effects of Lead on Cardiovascular Mortality
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
United States (cont'd)
Steenland et al. The death certificates of 1028 males of
(1992) the 1990 who worked at a smelter plant
U.S.-Idaho at least one yr between 1940 and 1965
>1941 to 1988 were examined to construct standardized
mortality ratios (SMR) for various ICD-9
disease classifications using the U.S.
population as a referent group.
X
ON
ON
In 1976 blood Pb of
173 workers avgd (SD)
56.3 ug/dL (12.9). Air
Pb was measured in
1975 at 3.1 mg/m3in
208 personal 8-h
samples. HighPb
departments in the plant
were defined as those
exceeding 0.2 mg/m3 in
the 1975 survey.
Non-malignant respiratory disease and accidents accounted for most of the
significantly elevated SMR in the group. SMRs were not significantly elevated
for ischemic heart disease (410-414), SMR = 0.94 (95% CI: 0.84,1.05);
hypertension with heart disease (402, 404), SMR = 0.97 (95% CI: 0.53, 1.63);
hypertension with no heart disease (401, 403, 405), SMR = 1.73 (95% CI: 0.63,
3.77); or cerebrovascular diseases (430-436), SMR = 1.05 (95% CI: 0.82, 1.32).
Similar results were found for the people working in the "high Pb departments."
Though there is no doubt that this group was highly exposed to Pb, exposure
characterization over the working lifetime was not well defined, few blood Pb
data were available, and poor demographic data for the exposed group only
allowed a comparison with total U.S. population. As is usual with occupationally
exposed groups, selection bias may influence results. No smoking data were
available for the group. In industrial conditions smoking will be confounded
with other Pb exposure (constant hand to mouth behavior on the plant floor will
exposure smokers to more Pb via the oral route than in non-smokers).
-------
Table AX6-5.3 (cont'd). Effects of Lead on Cardiovascular Mortality
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings, Interpretation
X
ON
ON
Europe
Gerhardsson et al.
(1995)
Europe- southern
Sweden
1969-1989
664 male workers at a secondary Pb
smelter had blood Pb tested every 2-3
mos since 1969. The past blood Pb level
of 201 workers who had been working at
the plant from before 1969 was estimated
from their 1969 results. Median (10th
percentile, 90th percentile) yr of birth
was 1943 (1918, 1960). Median(10th
percentile, 90th percentile) duration of
employment was 2.8 yrs (0.3, 25.7) and
median (10th percentile, 90th percentile)
duration of followup was 13.8 yrs (2.8,
20.9). A total of 8706 person-yrs were
represented in the study. Standardized
mortality ratios based on county
mortality tables by calendar yr, cause,
sex and five-yr age group were
calculated. Cardiovascular diseases were
coded by ICD-8 from death certificates.
Arithmetic mean blood
Pb levels dropped from
-62 ug/dLin!969to
-33 ug/dLin!985.
95% CI were difficult
to extract from the
presented graph, but
appeared to be no more
than 5-6 ug/dL about
the mean.
All cardiovascular disease mortality (ICD-8 390-458) was significantly elevated
above that expected from the county mortality tables (SMR = 1.46 [95% CI:
1.05, 2.02]), with 39 of the 85 deaths observed in the cohort. For just ischemic
heart disease (ICD-8 410-414), SMR = 1.72 (95% CI: 1.20, 2.42) in the plant
workers with 34 of the 85 deaths observed in the cohort. There were no deaths
recorded for cerebrovascular diseases (ICD-9 430-438). There was no apparent
concentration-response relationship, using peak blood Pb and time-integrated
blood Pb.
Problems inherent in using standardized mortality ratios in such mortality studies
have been discussed above. The sample size was too small (85 all cause deaths
among 664 workers) to interpret non-significant results.
Mailer and
Kristensen(1992)
Europe-Denmark-
Copenhagen
County-Glostrup
Population Studies
1976-1990
See Mailer et al. (1992) entry in Blood
Pressure and Hypertension for results of
cardiovascular disease and coronary heart
disease mortality.
-------
Table AX6-5.4. Cardiovascular Effects of Lead on Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States
Chen et al. (2006)
U.S.-Baltimore, MD;
Cincinnati, OH;
Newark, NJ;
Philadelphia, PA
-1998-2004
X
ON
ON
780 children from 12-33 mos participated
in a randomized clinical trial of oral
succimer chelation in four clinical
centers. Half the children had up to three
26-day treatments, the other half were
given placebo. 75% got two treatment
sessions and 81% of those with two
treatments received a third.
Blood pressure was measured pre-
treatment, at 7, 28, and 42 days after each
treatment, then every 3 to 4 mos for five
yrs of follow up. Cross-sectional
multiple regression models adjusting for
clinic location, baseline linear Pb, race,
sex, parents' education, single parent, age
at test, height at test, and BMI at test for
each period of the study tested the
difference of diastolic and systolic blood
pressure between placebo and succimer
groups. Cross-sectional multiple
regression models for the effect of linear
blood Pb at each period on blood
pressure adjusted for clinic location,
treatment group, race, sex, parents'
education, single parent, age at test,
height and BMI. Two mixed models,
one from start of treatment to 9-mo
follow up, the other from 12 to 60 mos
follow up, adjusted for the same
variables, and tested the effect of
treatment group over time.
Blood Pb ranged from
20-44 ug/dL at pre-treatment
and from 1-27 ug/dL at 5 yr
follow up. Succimer-treated
group had significantly
lower blood Pb than placebo
group only for 9-10 mos
following the end of
treatment. Blood Pb did not
differ significantly beyond
that period.
Adjusted systolic blood pressure was significantly higher in the succimer
group than the placebo group at 36 mos (1.27 mm Hg [95% CI: 0.06,
2.48]) and at 60 mos followup (1.69 mm Hg [95% CI: 0.34, 3.04]).
Systolic blood pressure was not significantly different at any other time
period; diastolic blood pressure was never significantly different between
groups.
Concurrent linear blood Pb was not associated with blood pressure in
cross-sectional models at any time point in the study. Adjusted
coefficients for linear blood Pb and systolic blood pressure ranged from
1.36 mm Hg (95% CI: 10.58, 3.30) at pre-treatment to !0.72 mm Hg (95%
CI: !1.91, 0.48)at 36 mos of followup. Diastolic pressure coefficients
were generally lower but followed the same pattern.
Mixed model analysis for start of treatment through 9 mos follow up
showed succimer treatment effect of 0.24 mm Hg (95% CI: 10.79, 1.28)
for systolic and 0.46 mm Hg (95% CI: 10.44, 1.36) for diastolic blood
pressure. The treatment effect from 12 through 60 mos follow up was
1.09 mm Hg (95% CI: 0.27, 1.90) systolic and 0.15 mm Hg (95% CI:
10.45, 0.75) for diastolic blood pressure.
The only reliable effect of succimer treatment was an elevation of systolic
blood pressure, especially notable between three and five yrs post
treatment. The authors could not account for the apparent increase in
blood pressure in the succimer-treated group 3-5 yrs after treatment ended.
It is notable that the two groups had different mean blood Pb for less than
a yr after succimer treatment ended, a period perhaps too short to observe
any beneficial effect of treatment. Failure to find cross-sectional effects of
blood Pb on blood pressure, especially pre-treatment, may indicate that Pb
exposure for a period of less than three yrs after birth is not sufficient to
affect blood pressure or that blood pressure measurements in the first three
yrs of life are highly variable, as could be seen from scatter plots of blood
pressure vs. blood Pb at pre-treatment compared 60 mo follow up. The
use of linear Pb term may have reduced sensitivity to finding a significant
blood Pb effect on blood pressure. No model diagnostics mentioned.
-------
Table AX6-5.4 (cont'd). Cardiovascular Effects of Lead on Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
X
ON
ON
United States (cont'd)
Gump et al. (2005)
U.S.-Oswego,NY
Dates of study not
122 9.5-yr old children participated.
Multiple regression models of percent
changes in systolic and diastolic blood
pressure, heart rate, stroke volume,
cardiac output, and total peripheral
resistance due to acute stress were
adjusted by stepwise entry of up to
50 possible control variables with
quartile blood Pb forced in last. A linear
contrast was used to test dose-response
effects of quartile Pb. Linear Pb terms
were also used.
Contemporary blood Pb
quartile:
1st quartile: 1.5-2.8 ng/dL
2nd quartile: 2.9-4.1 ug/dL
3rd quartile: 4.2-5.4 ug/dL
4th quartile: 5.5-13.1 ug/dL
All 3 represent percent change in outcome from nonstress to stress
condition for each change in 1 ug/dL blood Pb.
Systolic blood pressure: 3 = 10.009 (95% CI: 10.74,0.055)
Diastolic blood pressure: 3 = 0.069 (95% CI: !0.001, 0.138)
Heart rate: 3 = 0.013 (95% CI: 10.046,0.072)
Stroke volume: 3 = 10.069 (95% CI: 10.124, 10.015)
Cardiac output: 3 = 10.056 (95% CI: !0.113, 0.001)
Total peripheral resistance: 3 = 0.088 (95% CI: 0.024, 0.152)
Mean successive difference of cardiac interbeat interval:
3 = 10.028 (95% CI: (10.098,0.042)
Despite low power to detect significant effects, blood pressure, cardiac
output, and total peripheral resistance change to stress were associated
with contemporary blood Pb. Stepwise modeling creates unique
models for each outcome. Some models had up to 12 control variables
plus Pb, an excessive number for only 122 subjects. Scatter plots of
regression with linear Pb and bar charts of response to quartile Pb
showed obvious non-linearity, though all Pb effects were modeled as
linear effects. Probability of contemporary exposure to mercury and
PCB's was very high. No model diagnostic testing reported.
Europe
Factor-Litvak et al.
(1996)
Europe-Kosovska
Mitrovica and Pristina,
Kosovo
-1992-1993
281 5.5-yr old children studied since
pregnancy participated. Multiple linear
regression models of systolic blood
pressure, adjusted for height, BMI,
gender, ethnic group, and birth order, and
diastolic blood pressure, adjusted for
waist circumference, ethnic group, and
birth order were constructed by stepwise
elimination from a larger pool of
potential confounding variables and
retained if they modified the linear blood
Pb coefficient by more the 10%.
Blood Pb arithmetic mean
(range):
22.7 ug/dL (5-55)
For each increase of 1 ug/dL of blood Pb:
Systolic blood pressure: 3 = 0.054 (95% CI: !0.024, 0.13)
Diastolic blood pressure: 3 = 0.042 (95% CI: 10.01, 0.090)
Despite low power to detect significant effects, there was a marginally
significant tendency for blood pressure to be positively associated with
blood Pb. Stepwise multiple regression may have capitalized on
chance results. The linear Pb term may have reduced the ability to
detect significant effects of Pb if the modeled relationship were
nonlinear. Log Pb was tested but not reported. A quadratic Pb term
was reported nonsignificant. No model diagnostics reported.
-------
ANNEX TABLES AX6-6
AX6-168
-------
Table AX6-6.1. Placental Transfer of Lead from Mother to Fetus
Reference and
Study Location
Study Description
Pb Measurement
Findings, Interpretation
X
ON
ON
United States
Harville et al. (2005)
Pittsburgh, PA
Angell and Lavery
(1982)
Louisville, KY
Bogdenetal. (1978)
Newark, NJ
159 mother-infant pairs.
635 cord blood specimens. 154 maternal
and infant blood samples collected 24 h
postpartum from these deliveries.
25 deliveries of infants with birth weights
between l,500-2,500g and 50 matched
controls with birth weights above 2,500g.
Maternal blood Pb at delivery:
Mean 1.93 ng/dL (range 0.55-4.70)
Cord blood Pb:
Mean 1.64 ng/dL (range 0.05-3.95)
Maternal blood Pb:
Mean9.85|ig/dL(SD4.4)
Infant blood Pb:
Mean9.82|ig/dL(SD4.8)
Cord blood Pb:
Mean9.78|ig/dL(SD4.1)
Low birth weight infants:
Maternal blood Pb:
Meanl6.2|ig/dL(SD4.5)
Cord blood Pb:
Meanl3.8|ig/dL(SD4.4)
Normal birth weight infants:
Maternal blood Pb:
Meanl5.3|ig/dL(SD5.2)
Cord blood Pb:
Mean 13.1 ng/dL (SD 4.3)
Correlation coefficient = 0.79
On avg, cord blood Pb was lower than maternal
blood Pb by 0.03 ng/dL (95% CI: 0.21, 0.38).
Maternal-infant blood Pb:
Correlation coefficient = 0.73, 3 = 0.73
Maternal-cord blood Pb:
Correlation coefficient = 0.60, 3 = 0.55
Cord-infant blood Pb:
Correlation coefficient = 0.77, 3 = 0.90
No significant differences in maternal blood to
cord blood ratios in low birth weight and normal
birth weight infants.
Correlation coefficient = 0.55
-------
Table AX6-6.1 (cont'd). Placental Transfer of Lead from Mother to Fetus
Reference and
Study Location
Study Description
Pb Measurement
Findings, Interpretation
United States (cont'd)
Fahimetal. (1976)
Missouri
249 mother-infant pairs from Columbia.
Samples also collected from 253 mothers
from Rolla who delivered near Pb mining
areas.
X
Term pregnancies:
Columbia (n = 240):
Maternal blood Pb:
Mean 13.1 ng/100 g (SE 0.31)
Fetal blood Pb:
Mean4.3|ig/100g(SE0.10)
Placenta blood Pb:
Mean 7.0 ng/100 g (SE 0.01)
Cord blood Pb:
Mean 11.0 ng/100 g (SE 0.31)
Rolla (n= 177):
Maternal blood Pb:
Mean 14.3 ng/100 g (SE 0.16)
Fetal blood Pb:
Mean 4.6 ng/100 g (SE 0.08)
Placenta blood Pb:
Mean 8.0 ng/100 g (SE 0.06)
Cord blood Pb:
Mean 11.0 ng/100 g (SE 0.14)
Maternal-fetal blood Pb:
Correlation coefficient = 0.29
-------
Table AX6-6.1 (cont'd). Placental Transfer of Lead from Mother to Fetus
Reference and
Study Location
Study Description
Pb Measurement
Findings, Interpretation
United States (cont'd)
Gershanik et al. 98 mother-infant pairs.
(1974)
Shreveport, LA
Maternal blood Pb during labor:
Mean 10.3 ng/dL
Cord blood Pb:
Mean 10.1 ng/dL
Correlation coefficient = 0.64
X
Europe
Graziano et al.
(1990)
Kosovo, Yugoslavia
Hueletal. (1981)
France
Lauwerys et al.
(1978); Rods etal.
(1978) Belgium
902 births in Titova Mitrovica, site of a
large Pb smelter, refinery, and battery
factory, and Pristina, a non-Pb-exposed
control town.
Hair sample pairs (n = 100) from mothers
and newboms at time of delivery.
474 mother-infant pairs from Antwerp,
Brussels, Leuven, Toumai, and Vilvoorde.
Maternal blood Pb at mid-pregnancy:
Geometric means:
Titova Mitrovica 17.1 ng/dL (95% CI:
16.9,42.6)
Pristina 5.1 ng/dL (95% CI: 2.5, 10.6)
Maternal hair Pb:
Geometric mean 8.5 ng
Fetal hair Pb:
Geometric mean 7.3 ng/dL
Maternal blood Pb:
Mean 10.1 ng/dL (range 3.1-31)
Infant blood Pb:
Mean 8.3 ng/dL (range 2.7-27.3)
Placenta blood Pb:
Median 7.5 jig/100 g wet weight (range 1.1-39.5)
Maternal blood Pb at delivery and cord
blood Pb:
Correlation coefficient = 0.920, 3 = 0.928
Correlation coefficient = 0.24
Maternal-infant blood Pb:
Correlation coefficient = 0.81, 3 = 0.73
hi placenta-maternal blood Pb:
Correlation coefficient = 0.22
hi placenta-infant blood Pb:
Correlation coefficient = 0.28
Barltrop(1969)
England
29 paired maternal and fetal samples.
Maternal blood Pb:
Meanl3.9|ig/100g
Cord blood Pb:
Mean 10.8 ng/100 g
Correlation coefficient = O.i
-------
Table AX6-6.1 (cont'd). Placental Transfer of Lead from Mother to Fetus
Reference and
Study Location
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Barltrop(1969)
England
34 fetuses at gestational age 10 to 40 wks
obtained from termination of pregnancy and
neonatal deaths.
Blood Pb levels in femur, liver, blood, brain, heart,
and kidney measured.
Pb became detectable at gestational age 12 -14
wks. For skeletal (femur) and soft tissue with
high affinity (liver), Pb levels increased
progressively until term. In contrast, in soft
tissue with low affinity (heart), only a modest
increase in Pb levels was observed between 14
wks and term.
Latin America
Chuangetal. (2001)
Mexico City, Mexico
X
to
615 women recruited in 1994-1995.
Investigators used structural equation
modeling to estimate plasma Pb as the
unmeasured variable and to quantify the
interrelations of cord blood Pb with plasma
Pb, whole blood Pb, and bone Pb (cortical
and trabecular).
Maternal whole blood Pb:
Mean 8.45 ng/dL (SD 3.94)
Maternal patella bone Pb:
Mean 14.24 ng/g bone mineral (SD 14.19)
Maternal tibia bone Pb:
Mean 9.67 ng/g bone mineral (SD 9.21)
Cord blood Pb:
Mean 6.55 ng/dL (SD 3.45)
hi cord-In maternal whole blood Pb:
Correlation coefficient = 0.82
hi cord-In maternal plasma Pb:
Correlation coefficient = 0.89
hi cord-maternal patella Pb:
Correlation coefficient = 0.23
hi cord-maternal tibia Pb:
Correlation coefficient 0.18
The structural equation models indicated that
maternal plasma Pb had a stronger association
with fetal cord blood Pb compared to that of
whole blood Pb. In addition, the models
suggested a significant contribution of Pb from
the skeletal system to plasma during pregnancy,
a contribution that is independent of the
influence of maternal whole blood Pb.
-------
Table AX6-6.1 (cont'd). Placental Transfer of Lead from Mother to Fetus
Reference and
Study Location
Study Description
Pb Measurement
Findings, Interpretation
X
Other Locations
Clark (1977)
Zambia
Casey and Robinson
(1978)
New Zealand
Chaubeetal. (1972)
122 mother-infant pairs residing near the
Broken Hill Pb Mine and Smelter. Control
group of 31 mother-infant pairs.
40 fetuses (23 stillborn and 17 died within
24 hrs), 22 to 43 wks gestation.
50 embryos and fetuses 31 to 261 days
gestational age that were aborted.
Mine group:
Maternal blood Pb:
Mean41.2ng/dL(SD14.4)
Infant cord blood Pb:
Mean37.0|ig/dL(SD15.3)
Control group:
Maternal blood Pb:
Mean 14.7 ng/dL (SD 7.5)
Infant cord blood Pb:
Meanll.8ng/dL(SD5.6)
Pb detected in 73% of liver, 23% of kidneys, 40%
of brain, 25% of heart, 33% skeletal muscle, and
70% of bone samples. Pb also detected in 11 of 14
lung samples (79%).
Overall Pb concentration in soft tissue:
0.1-2.4 ng/g dry matter
Pb concentration in bone samples:
0.4-4.3 ng/g dry matter
Among the 1 st trimester specimens:
Pb detected in 77% of liver, 15% of brain, and 30%
of kidney samples.
Mine group:
Correlation coefficient = 0.77
Control group:
Correlation coefficient = 0.56
Pb concentrations in bone were higher than in
the other tissues.
Levels in brain, heart, and muscle similar to
values reported for children and adults. Levels
in liver, kidney, lung, and bone were much less
than adult values, suggesting much of the Pb that
enters the body after birth accumulates in these
tissues.
Placental transfer occurs as early as the 1 st
trimester of pregnancy.
-------
Table AX6-6.2. Lead Exposure and Male Reproduction: Semen Quality
Reference and
Study Location
Study Description
Pb Measurement
Findings, Interpretation
United States
Benoffetal. (2003a)
New York
74 male partners of women undergoing
their first in vitro fertilization cycle.
Seminal plasma Pb:
Mean 39.50 ug/dL (SD 35.97)
X
Benoffetal. (2003b)
New York
1 5 semen donors in an artificial
insemination program. None were
occupationally exposed to Pb.
Seminal plasma Pb:
Range <\0 to >150 ug/dL
Significant negative correlation between seminal
plasma Pb and fertilization rate (r = !0.447).
Statistically significant inverse correlations (r
values of
-------
Table AX6-6.2 (cont'd). Lead Exposure and Male Reproduction: Semen Quality
Reference and
Study Location
Study Description
Pb Measurement
Findings, Interpretation
X
Canada
Alexander et al.
(1996a)
British Columbia
119 workers employed at a Pb smelter.
Current blood Pb:
Mean 22.4 ng/dL (range 5-58)
Sperm concentration and total sperm count were
inversely related to current blood Pb
concentration, with the largest effects detected
among men with blood Pb concentrations of 40
Hg/dL or more.
Geometric mean
Blood Pb dig/dP sperm countxlO6
<\5 186.0
15-24 153.0
25-39 137.0
340 89.1
Blood Pb levels were not consistently associated
with abnormal morphology and poor motility of
the sperm.
When classified by long term exposure to
Pb, calculated from the mean blood Pb
concentrations of the preceding 10 yrs, similar
trends were observed.
-------
Table AX6-6.2 (cont'd). Lead Exposure and Male Reproduction: Semen Quality
Reference and
Study Location
Study Description
Pb Measurement
Findings, Interpretation
X
Oi
Oi
Europe
Bonde et al. (2002)
UK, Belgium, Italy
Assennato et al.
(1986)
Italy
Lancranjan et al.
(1975)
Europe
European study of 503 men (362 exposed to Blood Pb:
Pb, 141 unexposed controls) employed in
Pb industry. Exposed workers:
Mean 31.0 ug/dL (range 4.6-64.5)
Unexposed workers:
Mean 4.4 ug/dL
18 battery workers (exposed group) and 18
cement workers (control group).
150 men occupationally exposed to Pb
divided into four groups: Pb-poisoned
workmen (n = 23) and those showing a
moderate (n = 42), slight (n = 35), or
physiologic absorption (n = 50).
Blood Pb:
Battery workers:
Mean 61 ug/dL (SD 20)
Cement workers:
Mean 18 ug/dL (SD 5)
Semen Pb:
Battery workers:
Mean 79 ug/dL (SD 36)
Cement workers:
Mean 22 ug/dL (SD 9)
Blood Pb:
Pb poisoned workers:
Mean 74.5 ug/dL
Moderately exposed workers:
Mean 52.8 ug/dL
Median sperm concentration reduced by 49% in
men with blood Pb levels >50 ug/dL.
Odds ratio for sperm count #50 million/ml in
men with blood Pb levels >50 ug/dL compared
to <\0 ug/dL was 4.4 (95% CI: 1.6, 11.6).
Regression analyses indicated a threshold value
of 44 ug/dL below which no adverse
associations were found.
Sperm count and blood Pb:
T2= !0.385
Sperm count and sperm Pb:
r2 = !0.026
38% lower median sperm count and threefold
greater prevalence of oligospermia (16.7% vs.
5.5%) in battery workers compared to cement
workers.
Decreased sperm counts and increased
prevalence of morphologically abnormal sperm
amongst workers with heavy and moderate
exposure to Pb.
-------
Table AX6-6.2 (cont'd). Lead Exposure and Male Reproduction: Semen Quality
Reference and
Study Location
Study Description
Pb Measurement
Findings, Interpretation
X
Latin America
Hemandez-Ochoa
etal. (2005)
Region Lagunera,
Mexico
Lerda(1992)
Argentina
68 environmentally-exposed men residing
in Torreon, Gomez Palacio, and Lerdo for
at least 3 yrs.
Blood Pb:
Geometric mean 9.3 ng/dL (range 2-24)
Seminal fluid Pb:
Geometric mean 2.02 |ig/L (range 1.14-12.4)
Pb in spermatozoa:
Geometric mean 0.047 ng/106 cells (range 0.032-
0.245)
38 male workers exposed to Pb in a battery Blood Pb:
factory and 30 controls.
A (n = 12): mean 86.6 ng/dL (SD 0.6)
B(n=ll): mean65.9 ng/dL(SD 1.6)
C (n = 15): mean 48.6 ng/dL (SD 4.2)
Controls (n = 30): mean 23.5 ng/dL (SD 1.4)
Decreased sperm concentration, motility, normal
morphology and viability correlated with Pb in
spermatozoa. Reduced semen volume associated
with seminal fluid Pb.
Multiple linear regression indicated that
percentages of progressive motility and
morphology were the most sensitive parameters
to Pb toxicity, which showed the highest
percentages of abnormality among the semen
quality parameters
evaluated.
No associations were found with blood Pb.
Decreased sperm count, decreased percent
motility, and increased percent with abnormal
morphology observed in all three exposure
groups compared to control group.
Asia
Chowdhury et al.
(1986)
India
Ten men occupationally exposed to Pb in a
printing press.
Blood Pb:
Exposed group:
Mean 42.5 ng/dL
Unexposed group:
Mean 14.8 ng/dL
Decrease in sperm count, percent motility and
increase in number of sperm with abnormal
morphology observed in these semen samples.
-------
Table AX6-6.3. Lead Exposure and Male Reproduction: Time to Pregnancy
Reference and
Study Location
Europe
Joffe et al. (2003)
Belgium, England,
Finland, Italy
Study Description
Asclepios Project, large European
collaborative cross-sectional study.
1,108 men (638 occupationally exposed to
Pb at the time of pregnancy) who have
fathered a child.
Blood Pb
Belgium:
England:
Finland:
Pb Measurement
mean 31.7 |ig/dL
mean 37.2 |ig/dL
mean 29. 3 |ig/dL
Findings,
Blood Pb (>g/dU
control
<20
20-29
30-39
340
Interpretation
Fecundity density
ratios (95% CD
1.00
1.12(0.84,1.49)
0.96(0.77,1.19)
0.88(0.70,1.10)
0.93(0.76,1.15)
Italy: mean 29.2 ng/dL
X
Results indicate that no association was found
between blood Pb and delayed time to
pregnancy. Similar results were found when
duration of exposure or cumulative exposure was
used as the exposure metric.
oo
Apostoli et al. (2000)
Italy
Italian men included in the Asclepios
project. 251 exposed men and 45
unexposed men with at least one completed
pregnancy.
Blood Pb distribution among exposed men:
Blood Pb l>g/dL)
0-19
20-29
30-39
340
Percentage
of population
14%
40%
32%
14%
Time to pregnancy shorter in couples in which
male partner exposed compared to unexposed.
Among the exposed men, a longer time to
pregnancy observed with blood Pb levels
340 ng/dL, though not statistically significant.
-------
Table AX6-6.3 (cont'd). Lead Exposure and Male Reproduction: Time to Pregnancy
X
VO
Reference and
Study Location
Europe (cont'd)
Sallnr&n et al.
(2000a)
Finland
Asia
Shiau, et al. (2004)
Taiwan
Study Description
502 occupationally exposed males
monitored by the Finnish Institute of
Occupational Health.
280 pregnancies in 133 couples in which
male partner employed in battery plant.
127 conceived during exposure; remainder
conceived prior to exposure.
Pb Measurement
Blood Pb distribution (available close to time of
conception in 62% of men; in 38% estimated based
on blood Pb levels obtained at other times or based
on job hi stories):
Percentage
Blood Pb (ug/dL) of population
<\0 35%
10-20 40%
21-30 16%
31-39 4%
340 5%
Blood Pb:
Annual means from 1987 to 1999 ranged from 32
to 41 ng/dL.
Findings, Interpretation
Results suggest that paternal exposure to Pb may
be associated with increased time to pregnancy.
Fecundity density
Blood Pb Qg/dL) ratios (95% CD
<\0 1.00
10-20 0.92(0.73,1.16)
21-30 0.89(0.66,1.20)
31-39 0.58(0.33,0.96)
340 0.83 (0.50, 1.32)
Fecundity density
Blood Pb (iig/dL) ratios (95% CD
unexposed 1 .00
<20 0.91(0.61,1.35)
20-29 0.71(0.46,1.09)
30-39 0.50 (0.34, 0.74)
340 0.38 (0.26, 0.56)
Using blood Pb as a continuous variable and
restricting the analysis to blood Pb levels
between 10 and 40 |ig/dL, time to pregnancy
increased by 0.15 mos for each 1 ng/dL increase
in blood Pb level.
-------
Table AX6-6.4. Lead Exposure and Male Reproduction: Reproductive History
Reference and
Study Location
Study Description
Pb Measurement
Findings, Interpretation
United States
Lin etal. (1996)
New York
4,256 male workers reported to the New
York State Heavy Metals Registry
(exposed) and 5,148 male bus drivers from
the New York State Department of Motor
Vehicles file (control), frequency-matched
for age and residence. Fertility during the
period of 1981 to 1992. Records linked to
birth certificates from the New York State
Office of Vital Statistics.
Blood Pb in Pb-exposed men:
Mean 37.2 ng/dL(SD 11.1)
Standardized fertility ratio of Pb-exposed men in
comparison with non-exposed men was 0.88
(95% CI: 0.81,0.95).
Exposed group had fewer births than expected.
Among those employed in Pb industry over
5 yrs, a relative risk of 0.38 (95% CI: 0.23,
0.61) was observed after adjusting for age, race,
education, and residence.
X
oo
o
Europe
Gennartetal. (1992)
Belgium
74 men occupationally exposed to Pb for
more than 1 yr and 138 men in reference
group with no occupational exposure.
Bonde and Kolstad
(1997)
Denmark
1,349 male employees ages 20-49 yrs from
three battery plants and control group of
9,656 men not employed in Pb industry.
Cohorts identified by records in a national
pension fund. Information on births
obtained from Danish Population Register.
Blood Pb in Pb-exposed men:
Mean 40.3 ng/dL
Duration of Pb exposure:
Mean 10.7 yrs
Blood Pb in subset of battery worker cohort (4,639
blood samples from 400 workers):
Mean35.9|ig/dL(SD13.0)
Compared to reference group, odds of at least
one live birth reduced in exposed group during
the period of Pb exposure (odds ratio of 0.65
[95% CI: 0.43,0.98]).
Fertility decreased with increasing exposure
(although number of men at higher exposure
levels small).
No associations found between exposure
measure and birth rate.
Relative risk comparing person yrs at risk from
Pb exposure with yrs at risk in reference group
was 0.88 (95% CI: 0.81,0.95).
-------
Table AX6-6.4 (cont'd). Lead Exposure and Male Reproduction: Reproductive History
X
oo
Reference and
Study Location
Europe (cont'd)
Sallm&n et al.
(2000b)
Finland
Study Description
Occupationally exposed males monitored
by the Finnish Institute of Occupational
Health. 2,111 individuals with probable
exposure (a blood Pb level 310 |ig/dL
within a 5-yr time period including a
calendar yr preceding the yr of marriage
and 4 consecutive yrs) and 681 controls
(with mean blood Pb levels <10 |ig/dL).
Pb Measurement
Blood Pb distribution
exposed:
Blood Pb (fig/dL)
10-20
21-30
31-40
41-50
351
among individuals probably
Percentage
of population
51%
30%
11%
5%
3%
Findings, Interpretation
Risk ratios among men in the probably exposed
group:
Blood Pb l>g/dL) Infertility ratios (95% CD
controls 1 .00
10-20 1.27(1.08,1.51)
21-30 1.35(1.12,1.63)
31-40 1.37(1.08,1.72)
41-50 1.50(1.08,2.02)
351 1.90(1.30,2.59)
Results suggest that paternal exposure to Pb
increases the risk of infertility at low
occupational exposure levels.
-------
ANNEX TABLES AX6-7
AX6-182
-------
Table AX6-7.1. Recent Studies of Lead Exposure and Genotoxicity
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings and Interpretation
Europe
Fracasso et al. (2002)
Italy
X
oo
Case-control design.
37 workers employed at a battery plant.
29 student and office worker volunteers
with no known occupational exposure to
genotoxins.
Peripheral lymphocytes isolated from
whole blood.
Reactive Oxygen Species (ROS)
production, cellular GSH level, PKC
isoforms, and DNA breaks (via comet)
assayed.
ANOVA and logistic regression used to
compare workers vs. healthy volunteers.
Adjusted for age, alcohol use, and
smoking.
Battery plant workers. Blood Pb
categories used for some
comparisons, with <25, 25-35, and
>35 ug/lOOmL as cutpoints.
Mean blood Pb 39.6 ug/lOOmL for
workers, 4.4 ug/lOOmL for
volunteers.
OR (95% CI)
Workers vs. Volunteers:
ROS: 1.43(0.79,2.60)
DNA breaks (tail moment): 1.07 (1.02, 1.12)
GSH: 0.64(0.49,0.82)
PKC a reduced in workers, atypical PKC unchanged vs.
volunteers (no statistics provided).
Means (SE) via blood Pb category for ROS and GSH:
<25ug/100mL 4.9 (0.4) and 12.8 (0.8)
25-35 ug/lOOmL 5.4 (0.7) and 7.7 (1.7)
>35ug/100mL 5.4 (0.5) and 9.2 (1.2)
Major analyses controlled for age, smoking, and alcohol intake.
Analyses by blood Pb category not controlled for age, smoking,
or alcohol intake but these factors said not to influence endpoint
and/or results "significantly." No control for potential
coexposures.
-------
Table AX6-7.1 (cont'd). Recent Studies of Lead Exposure and Genotoxicity
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings and Interpretation
Europe
Palus et al. (2003)
Poland
X
oo
Cross-sectional design.
Battery plant workers: 34 acid battery,
22 alkaline battery, and 52 plant
personnel from departments with no
known exposure to Pb or cadmium.
Lymphocytes isolated from whole blood.
SCE, MN, DNA damage (via comet)
assayed.
Means compared via ANOVA.
Workers considered Pb-exposed if
from acid battery department,
cadmium-exposed if from alkaline,
unexposed if from other department.
Mean blood Pb 504 ug/L for
Pb-exposed workers, 57 ug/L for
cadmium-exposed, and 56 ug/L for
other workers.
Mean (SD)
Pb exposed workers (all combined):
SCEs 7.48 (0.88)
MN 18.63(5.01)
NDI 1.89 (no SD given)
Cadmium exposed workers (all combined):
SCEs 6.95 (0.79)
MN 15.86(4.92)
NDI 1.96 (no SD given)
Other-workers (all combined):
SCEs 6.28(1.04)
MN 6.55(3.88)
NDI 1.86 (no SD given)
Elevation of SCEs and MN vs. controls at p < 0.05 and
p < 0.01, respectively.
Both SCEs and MN elevated among Pb-exposed workers as well
as cadmium-exposed workers compared to controls. Differences
greatest for Pb-exposed workers.
Higher SCE and MN also occurred among Pb-exposed workers
after stratification by smoking status.
No direct control for potential coexposures, but mean blood
cadmium no higher in Pb-exposed than in other worker group.
-------
Table AX6-7.1 (cont'd). Recent Studies of Lead Exposure and Genotoxicity
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings and Interpretation
Europe (cont'd)
Van Larebeke et al.
(2004)
Belgium
Cross-sectional design.
99 female nonsmokers, ages 50-65,
drawn from rural and industrial areas.
Peripheral lymphocytes isolated from
blood. HPRT variant frequency
determined.
Pb concentration measured in blood
(serum).
Women also classified as above vs.
below median for blood Pb.
HPRT variant frequency
Above median serum Pb: 9.45 H Iff6
Below median serum Pb: 5.21 H Iff6
P-value for difference = 0.08 adjusted for age, education,
smoking, BMI, and serum selenium. (Significant inverse
association noted between variant frequency and serum
selenium.) Uncontrolled for potential exposure to other
genotoxins.
X
oo
Latin America
Minozzo et al. (2004)
Brazil
Cross-sectional design.
26 workers employed at a battery
recyclery for 0.5 to 30 yrs.
29 healthy volunteers of similar age
range and SES.
Peripheral lymphocytes isolated from
whole blood.
Fixed blood slides stained with Giemsa
visually evaluated to determine
micronuclear frequency (MN) and
cellualr proliferation as nuclear
division index (NDI).
ANOVA and logistic regression used
to compare workers vs. healthy
volunteers. Adjusted for age, alcohol
use, and smoking.
Battery recyclery workers were
considered exposed.
Blood Pb also determined.
Mean blood Pb 35.4 ng/dL for
workers, 2.0 ng/dL for volunteers.
Means (SD)for -workers and volunteers
MN: 3.85 (2.36) and 1.45 (1.43)
NDI: 1.77 (0.22) and 1.89 (0.18)
Kendal correlation coefficient:
All workers {assuming recyclery workers only, not total
population, but no population number given in table.}
Blood PbHMN: 0.061 (p = 0.33)
Blood PbH NDI: 0.385 (p = 0.003)
Not controlled for age or SES, although worker and volunteer
populations said to be of similar age and SES. Uncontrolled for
potential coexposures. Correlations appear uncontrolled for
smoking, age, or other factors. Differences in MN and NDI
minor for smokers vs. nonsmoker, however. Diet "type"
"similar" for workers and controls, although no definition of
similarity provided.
-------
Table AX6-7.2. Key Occupational Studies of Lead Exposure and Cancer
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings and Interpretation
X
Oi
oo
Oi
United States
Steenlandetal. (1992)
(follow-up of Selevan
etal. (1985)
U.S.
1940-1988
Wong and Harris
(2000)
(follow-up of Cooper
etal. (1985)
U.S.
1947-1995
Cohort design.
1,990 male workers employed for
at least 1 yr in a Pb-exposed
department at a U.S. Pb smelter
in Idaho during 1940-1965.
Mortality traced through 1988 to
determine cause of death.
SMR computed for workers vs.
national rates for age-comparable
counterparts.
Cohort design.
Pb battery plant (4,518) and smelter
(2,300) workers.
Worker mortality was followed up
through 1995.
Cause of death was identified from
death certificates.
Mortality was compared with U.S.
national age-, calendar-yr-, and gender-
specific rates to compute the SMR.
(See additional entry for nested study
of stomach cancer.)
Exposure categorizations based on
airborne Pb measurements from
1975 survey. High-Pb-exposure
subgroup consisted of 1,436 workers
from departments with an avg of least
0.2 mg/m3 airborne Pb or >50% of
jobs showing 0.40 mg/m3 or greater.
Mean blood Pb 56 ug/dL in 1976.
Workers were evaluated as a whole,
and also as separate battery plant and
smelter worker populations.
Job histories were also used to
stratify workers by cumulative yrs of
employment (1-9, 10-19, 20+), date
of hire (pre-1946 vs. 1946 on), and
lag between exposure and cancer
(<20,20-34, >34 yrs). Mean blood
Pb 80 ug/dL during 1947-72 among
smelter workers, 63 ug/dL among
battery workers.
SMR (95% CI); number of deaths
Total cohort:
Nonsignificantly elevated RRs: kidney, bladder, stomach, and lung
cancer.
High-Pb-exposure subgroup:
Kidney
Bladder
Stomach
Lung
2.39 (1.03, 4.71); 8
1.33 (0.48, 2.90); 6
1.28(0.61,2.34); 10
1.11(0.82, 1.47); 49
No control for smoking or exposure to other metals.
SMR (95% CI)
Battery plant workers:
All cancer 1.05(0.97,1.13)
All respiratory 1.13 (0.98, 1.29)
Stomach 1.53(1.12,2.05)
Lung, trachea, bronchus 1.14 ( 0.99, 1.30)
Thyroid, Hodgkin's: nonsignificant
Bladder 0.49 (0.23, 0.90)
Smelter workers:
Digestive, respiratory, thyroid: nonsignificant
Lung 1.22(1.00,1.47)
Battery plant and smelter workers combined:
All cancer
All respiratory
Stomach
Lung, trachea, bronchus
Thyroid/endocrine
1.04(0.97,1.11)
1.15(1.03,1.28)
1.47(1.13,1.90)
1.16(1.04,1.30)
3.08(1.33,6.07)
Lung and stomach risks lower pre-1946 hires; higher for workers
employed 10-19 yrs than <10, but lower for >19 yrs; SMRs peaked
with 20- to 34-yr latency for lung, but <20 yrs for stomach.
No control for smoking or exposure to other agents. No assessment
of employment history after 1981.
-------
Table AX6-7.2 (cont'd). Key Occupational Studies of Lead Exposure and Cancer
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings and Interpretation
X
oo
United States (cont'd)
Wong and Harris
(2000)
U.S.
1947-1995.
(Nested in Wong and
Harris 200 cohort.)
Case-control design.
Cases: the 30 stomach cancer cases
occurring in a Philadelphia Pb battery
plant.
Controls'. 120 age-matched cohort
members.
Mean exposure was compared for
cases vs. controls. Odds of exposure
were also computed for increasing
quartiles of cumulative exposure.
Job titles were used to classify Pb
exposure as low, intermediate, or
high; total mos of any exposure, of
intermediate or high exposure only,
and of cumulative exposure, with
mos weighted by 1, 2, or 3 if spent in
low-, intermediate-, or high-exposure
job-
Mean mos of employment, of intermediate or high exposure, or of
weighted exposure to Pb were all nonsignificantly lower among
cases.
OR for cumulative weighted exposure in the 10 yrs prior to death:
Istquartile 1.00
2nd quartile 0.62
3rd quartile 0.82
4th quartile 0.61
p for trend = 0.47; ORs showed no positive association with
any index of exposure.
Analyses appear uncontrolled for smoking, other occupational
exposures, or other risk factors.
Europe
Fanning (1988)
(Cases overlap those
occurring in
Dingwall-Fordyce and
Lane, 1963; and
Malcolm and Barnett,
1982).
U.K.
1926-1985
Proportional mortality/cohort design.
Subjects: 2,073 deceased males
identified through pension records of
Pb battery and other factory workers in
the U.K.
Workers dying from a specific cancer
were compared with workers dying
from all other causes
Workers were classified as High or
moderate Pb exposure vs. little or no
exposure based on job titles.
OR (95% CI); number of deaths
Lung cancer: 0.93 (0.8, 1.1); 76
Stomach cancer: 1.34; 31
No associations for other cancer types; elevations in stomach and
total digestive cancers limited to the period before 1966.
-------
Table AX6-7.2 (cont'd). Key Occupational Studies of Lead Exposure and Cancer
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings and Interpretation
Europe (cont'd)
Anttilaetal. (1995)
Finland
1973-1988
X
oo
oo
Cohort plus case-referent design.
20,700 workers with at least one blood
Pb measurement between 1973 and
1983.
Workers were linked to the Finnish
Cancer Registry for follow-up through
1988. For deceased workers, cause of
death was identified from death
certificate.
Mortality and incidence were compared
with gender-, 5-yr age, and 4-yr
calendar-yr matched national rates.
Exposure was categorized according
to the highest peak blood level
measured:
Low: 0-0.9 nmol/L
(0-18.6 ng/dL)
Moderate: 1-1.9 |imol/L
(20.7-39.4 ng/dL)
High: 2-7.8 nmol/L
(41.4-161.6]
Mean blood Pb 26 ng/dL.
Total cohort:
No elevation in total or site-specific cancer mortality.
Moderately exposed:
Total respiratory and lung cancer:
SIR =1.4 (95% CI: 1.0, 1.9) for both
Total digestive, stomach, bladder, and nervous system:
nonsignificant elevations.
Highly exposed:
No increase in risks.
All cancer:
RR=1.4(95%CI: 1.1,1.8)
Lung or tracheal:
RR = 2.0(95%CI: 1.2,3.2)
No increase in high-exposure group.
No RRs reported for other cancers.
Case-referent substudies:
Lung cancer ORs increased with increasing cumulative
exposure to Pb.
Highly exposed: squamous-cell lung cancer OR of 4.1
(95% CI: 1.1, 15) after adjustment for smoking.
Short follow-up period limits statistical power, offset to a
large degree by the substantial sample size. No control for
exposure to other potential carcinogens.
-------
Table AX6-7.2 (cont'd). Key Occupational Studies of Lead Exposure and Cancer
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings and Interpretation
X
oo
VO
Europe (cont'd)
Anttilaetal. (1996)
Finland
1973-1988
(Nested analysis based
onAntillaetal., 1995
cohort)
Gerhardsson et al.
(1995)
Sweden
1969-1989
Case-control design.
(See Anttila et al., 1995 for basic
information on the source population.)
Cases'. 26 Finnish men with CNS
cancer.
Controls: 200 Finnish men without
CNS cancer.
Nested case-control analysis.
Cohort design.
684 male Swedish secondary Pb smelter
workers with Pb exposure.
Cancer incidence among workers was
traced through 1989.
Incidence was compared with county
rates.
Peak blood Pb levels used to
categorize exposure as 0.1-0.7,
0.8-1.3, and 1.4-4.3 ng/L.
Cumulative exposure estimated by
using mean annual blood Pb level to
categorize exposure as 0, 1-6, 7-14,
or 15-49 ng/L.
Interviews were used to obtain
occupational history and other risk-
factor data from patients or next
of kin.
Blood Pb level: any worker with a
detectable blood Pb level was
classified as exposed.
Number of cases or deaths
CNS cancer incidence (26 cases): Rose with increasing peak lifetime
blood Pb measurements; not significant.
Glioma mortality (16 deaths): Rose consistently and significantly
with peak and mean blood Pb level, duration of exposure, and
cumulative exposure.
Mortality by cumulative exposure, controlled for cadmium, gasoline,
and yr monitoring began:
Low (13 subjects) 2.0(2)
Medium (14 subjects) 6.2 (2)
High (16 subjects) 12.0(5)
One death among 26 subjects with no exposure: test for trend
significant at p = 0.02.
Controlled for smoking as well as exposure to cadmium and gasoline.
Complete follow-up with minimal disease misclassification.
SIR (95% CI); number of cases
All malignancies:
1.27(0.91, 1.74); 40
Respiratory:
1.32 (0.49, 2.88); 6
All gastrointestinal:
Cohort 1.84 (0.92, 3.29); 11
Highest quartile 2.34 (1.07, 4.45); 9
Stomach:
1.88(0.39, 5.50); 3
Colon:
1.46 (0.30, 4.28); 3
SIRs for all other sites except brain were nonsignificantly elevated;
too few cases.
No control for smoking. Small numbers, so meaningful dose-
response analyses not possible for most cancer sites.
-------
Table AX6-7.2 (cont'd). Key Occupational Studies of Lead Exposure and Cancer
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings and Interpretation
X
Europe (cont'd)
Lundstrom et al.
(1997)
(follow-up of
Gerhardsson et al.
(1986)
(see also subcohort
analyses of Englyst
etal.,2001).
Sweden
1928-1987
Englyst etal. (2001)
(follow-up and sub-
analysis of Lundstrom
etal., 1997).
Sweden
1928-1987
Cohort design.
3,979 copper and Pb smelter workers.
Standardized mortality and incidence
ratios were computed for workers
compared with age-, yr-, gender-, and
county-specific rates for the general
population.
Nested cohort analysis.
Limited to 1,093 workers in the
smelter's Pb department, followed
through 1997.
Incidence was compared with county
rates; age-specific SIRs with 15-yr lag.
For some analyses, the entire cohort
was treated as exposed. For others,
job histories were used to single out
1,992 workers belonging to
departments thought to be exposed to
"Pb only." Mean blood Pb
monitoring test results across time
were used to single out a "highly
exposed" group of 1,026 workers
with blood Pb levels >10 nmol/L
[>207ng/dL].
Mean blood Pb 60 ng/dL in 1959.
Workers were divided into
Subcohorts I and II for ever and
never worked in areas generally
associated with exposure to arsenic
or other known carcinogens (701 and
383 workers, respectively).
Detailed individual assessment of
arsenic exposure was made for all
lung-cancer cases.
SMR (95% CI); number of deaths
Lung:
Total cohort
Highly exposed
SIR (95% CI); number of cases
Lung with 15-yr lag:
Total cohort
Highly exposed
Pb-only
Pb-only highly exposed
2.8(2.0, 3.8); 39
2.8(1.8,4.5); 19
2.9 (2.1,4.0); 42
3.4 (2.2, 5.2); 23
3.1(1.7, 5.2); 14
5.1(2.0, 10.5); 7
Other highly exposed (total cohort), with 15-yr lag:
Brain 1.6 (0.4, 4.2); 4
Renal pelvis, ureter, bladder 1.8 (0.8, 3.4); 9
Kidney 0.9 (0.2, 2.5); 3
All cancer 1.1 (0.9, 1.4); 83
No control for smoking.
SIR (95% CI); number of cases
Subcohort I (coexposed):
Lung 2.4(1.2,4.5); 10
Subcohort II (not coexposed):
Lung 3.6(1.2, 8.3); 5
Subjects with lung cancer found to have history of "considerable"
exposure to arsenic: 9/10 among Subcohort I, 4/5 among
Subcohort II.
No control for smoking.
-------
Table AX6-7.2 (cont'd). Key Occupational Studies of Lead Exposure and Cancer
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings and Interpretation
X
Europe (cont'd)
Carta et al. (2003)
Sardinia
1972-2001
Cohort design.
918 Pb smelter workers.
Mortality traced from 1972 through
2001.
Standardized mortality ratios computed.
Smelter workers considered exposed.
Job histories also used to categorize
degree of exposure based on
environmental and blood Pb
measurements for specific
departments and tasks during
1985-2001.
SMR; number of cases
Smelter workers as a whole
All cancer 1.01; 108
Gastric cancer 1.22; 4
Lymphoma/leukemia 1.82; 6
Lung cancer 1.21; 18
Highly exposed workers
Lung cancer 1.96 (95% CI: 1.02, 3.68) for highest exposure
group, with statistically significant upward trend.
Analyses for worker population as a whole supported by
presence of dose-response pattern for lung cancer based on
estimated exposure. Modest population size, inability to assess
dose-response for cancers of interest other than lung. No control
for smoking or other occupational exposures.
-------
Table AX6-7.3. Key Studies of Lead Exposure and Cancer in the General Population
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings and Interpretation
X
to
United States
Jemal et al. (2002)
(same cohort as in
Lustberg and
Silbergeld, 2002
except for inclusion
criteria)
U.S.
1976-1992.
Cohort design.
3,592 white participants from the
1976-1980 NHANES II survey who
had blood Pb measured at entry.
Mortality was followed through 1992
via NDI and SSADMF.
RRs were calculated for the various
exposure groups compared to survey
participants with the lowest exposure,
adjusted for age and smoking.
Blood Pb (ng/dL) was measured
by atomic absorption and used to
classify subjects into exposure
quartiles or groups above vs.
below median exposure.
Median blood Pb 12
RR (95% CI); number of deaths
Lung (above vs. below median):
Total cohort 1.5 (0.7, 2.9); 71
Male 1.2 (0.6, 2.5); 52
Female 2.5 (0.7, 8.4); 19
Stomach (above vs. below median):
Total cohort 2.4 (0.3, 19.1); 5
Male 3.1(0.3, 37.4); 4
Female no deaths in referent group
All cancer: total cohort by quartile (age-adjusted) 1.0, 1.2, 1.3, 1.5
(p = 0.16 for trend).
Smoking was controlled for. Pb levels occurring in the general population
were examined, not just those in workers with high occupational exposure
potential. Exposure to other carcinogens were not examined. Potential for
residual confounding by degree and duration of smoking exists (only
controlled for never, former, current <1, current 1+ pack/day). Limited
case numbers yield low statistical power for stomach or other cancers.
-------
Table AX6-7.3 (cont'd). Key Studies of Lead Exposure and Cancer in the General Population
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings and Interpretation
X
United States
Lustberg and
Silbergeld (2002)
(same cohort as Jemal
et al., 2002 except for
inclusion criteria)
U.S.
1976-1992.
Cohort design.
4,190 U.S. participants from the 1976-
1980 NHANES II health and nutrition
survey who had blood Pb measured at
entry and whose levels fell below
30 ng/dL.
Mortality was followed through 1992
viaNDIandSSADMF.
RRs were calculated for the various
exposure groups compared to survey
participants with the lowest exposure,
adjusted for age, smoking and other
factors.
Blood Pb (ng/dL) measured by
atomic absorption was used to
classify subjects into exposure
groups:
Low: <10
Medium: 10-19
High: 20-19
Mean blood Pbl 4 |ig/dL.
RR (95% CI)
All cancer, vs. low exposure:
Medium 1.5(0.9,2.5)
High 1.7(1.0,2.8)
Lung, vs. low exposure:
Medium 1.7(0.6,4.8)
High 2.2(0.8,6.1)
Non-lung, vs. low exposure:
Medium 1.5(0.8,2.8)
High 1.5(0.8,2.8).
Significant upward trends noted for all-cause and for cardiovascular
mortality with increasing Pb category.
Smoking was controlled for in the analysis. Pb levels occurring in the
general population were examined, with individuals showing levels
consistent with intense occupational exposure excluded, thus allowing
exploration of potential effects outside of groups experiencing intense
occupational exposure. Exposure to other carcinogens were not examined.
Potential for residual confounding by degree and duration of smoking
exists (only controlled for never, former, current <1, current 1+ pack/day).
Limited case numbers yield low statistical power for stomach or other
cancers.
-------
Table AX6-7.4. Other Studies of Lead Exposure and Cancer
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings and Interpretation
X
United States
Mallinetal. (1989)
Illinois
1979-1984
Coccoetal. (1998a)
U.S.
1984-1992
Case-control design.
Cases: random sample of 10,013 deaths
from 7 specific cancers, identified from
death certificates for Illinois males
between 1979 and 1984.
Controls: 3,198 randomly selected
deaths from other causes.
Odds of exposure computed for glass
workers vs. other occupations.
Case-control design.
Cases: all 27,060 brain cancer deaths
occurring among persons aged 35 or
older during 1984-1992, from U.S.
24-state death certificate registry.
Controls: 4 gender-, race-, age-, and
region-matched controls per case
selected from deaths due to
nonmalignant causes.
Subjects were subdivided into 4 groups
by gender and race (white or African-
American) for all analyses.
Exposure was based on
occupations abstracted from
death certificates.
No specific measure of Pb
exposure; glass workers can be
considered potentially exposed.
A job-exposure matrix was
applied to death certificate-listed
occupations to categorize
persons as having low, medium,
or high probability and intensity
of exposure.
Brain cancer, white male glass workers:
OR = 3.0, p< 0.05
No significant associations for other cancer sites.
No control for smoking or other risk factors. Poor specificity for Pb
exposure.
Risk of brain cancer mortality increased consistently with intensity of
exposure among African-American males, but not other race-gender
groups.
Probability of exposure alone was not consistently associated with
risk.
In the high-probability group, risk increased with exposure intensity
for all groups except African-American women (only 1 death in the
high-probability group).
Exposure estimate was based solely on occupation listed on death
certificate, hence there was substantial opportunity for
misclassification.
-------
Table AX6-7.4 (cont'd). Other Studies of Lead Exposure and Cancer
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings and Interpretation
United States (cont'd)
Coccoetal. (1998b)
U.S.
1984-1992
X
Case-control design.
Cases: all 28,416 CNS cancer deaths
occurring among persons aged 35 or
older during 1984-1992, from U.S.
4-state death certificate registry.
Controls: 4 gender-, race-, age-, and
region-matched controls per case
selected from deaths due to
nonmalignant causes.
Subjects were subdivided into 4 groups
by gender and race (white or African-
American) for all analyses.
Death certificate listed industry
and occupation was used to
categorize decedents. No
estimates of Pb exposure
specifically.
OR (95% CI)
All occupations or industries with ORs above 1.0 and p < 0.05 in at
least one race-gender group were reported
Newspaper printing and publishing industry:
White male 1.4(1.1,1.8)
Black male 3.1(0.9,10.9)
Typesetting and compositing:
White male 2.0(1.1,3.8)
White female 1.3(0.4,3.8)
Black female 4.2 (0.6, 30.7)
No deaths among black males.
Only two Pb exposure associated occupations or industries showed a
statistically significant elevation of mortality. No specific measures
of Pb exposure. Occupation based solely on death certificate, hence
there was substantial opportunity for misclassification.
-------
Table AX6-7.4 (cont'd). Other Studies of Lead Exposure and Cancer
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings and Interpretation
United States (cont'd)
Coccoetal. (1999)
U.S.
1984-1996
X
Oi
Oi
Case-control design.
Cases: all 41,957 stomach cancer deaths
occurring among persons aged 35 or
older during 1984-1996, from U.S.
24-state death certificate registry.
Controls: 2 gender-, race-, age-, and
region-matched controls per case
selected from deaths due to
nonmalignant causes.
Subjects were subdivided into 4 groups
by gender and race (white or African-
American) for all analyses.
A job-exposure matrix was
applied to death certificate-
listed occupations to categorize
persons as having low, medium,
or high probability and intensity
of exposure.
OR (95% CI)
Adjusted for age, ethnicity, marital status, urban residence, and
socioeconomic status.
Elevated ORs:
White female, high probability of exposure 1.53 (1.10, 2.12)
Blackmale, high probability of exposure 1.15 (1.01, 1.32)
Black female, high probability of exposure 1.76 (0.74, 4.16)
Highly exposed group included 1,503 white and 453 black men and
65 white and 10 black women; no pattern of increase across exposure
levels.
Intensity of exposure showed no association with stomach cancer
except for black women:
Low 1.82(1.04,3.18)
Moderate 1.39
High 1.25
No control for other occupational exposures. Exposure estimate
based on occupation listed on death certificate and hence subject to
misclassification due to missing longest-held job.
-------
Table AX6-7.4 (cont'd). Other Studies of Lead Exposure and Cancer
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings and Interpretation
Canada
Rischetal. (1988)
Canada
1979-1982
X
Siemiatycki et al.
(1991)
Canada
Case-control design.
Cases: 826 Canadian men with
histologically confirmed bladder cancer
during 1979-1982.
Controls: 792 controls from
Canadian population, matched on age,
gender, and area.
Odds of exposure to Pb for cases vs.
controls were computed, adjusted for
smoking and other risk factors.
Case-control design.
Cases: 3,730 various histologically
confirmed cancers.
Controls: specific cancer types were
compared with other cancers as a control
group, excluding lung cancer.
Separate subgroup analysis was
restricted to French Canadians.
Subjects were interviewed
regarding length of
occupational exposure to Pb
compounds, as well as 17 other
substances.
Occupational exposure to
293 substances, including Pb,
was estimated from interviews.
Exposure was classified as
"any"; a subgroup with
"substantial" exposure also was
identified.
OR (95% CI)
61 men ever exposed to Pb (smoking-adjusted):
2.0(1.2,3.5)
Trend per lOyrs duration of exposure:
1.45(1.09,2.02)
No other substances showed significant associations with bladder
cancer.
Controlled for smoking, marital status, socioeconomic status,
education, ethnicity, and urban vs. rural residence.
No control for other occupational exposures. Low control interview
rate (53%), which could result in biased control sample.
OR (90% CI); number of cases
Any exposure to Pb:
Lung 1.1 (0.9,1.4); 326
(French Canadians only)
Stomach 1.2 (1.0, 1.6); 126
Bladder 1.3 (1.0,1.6); 155
(French Canadians only)
Kidney 1.2 (1.0, 1.6); 88
ORs rose in the "substantial" exposure subgroup for stomach and
lung, but not for bladder or kidney cancer.
Controlled for smoking but not for other occupational exposures.
-------
Table AX6-7.4 (cont'd). Other Studies of Lead Exposure and Cancer
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings and Interpretation
Europe
Sankilaetal. (1990)
Finland
1941-1977
X
oo
Kauppinen et al.
(1992)
Finland
1976-1981
Cohort design.
1,803 male and 1,946 female glass
workers employed for at least 3 mos at
one of 2 Finnish glass factories in 1953-
1971 or 1941-1977.
Cancer incidence was compared with
age-, gender-, and calendar-yr-specific
national rates.
Stomach, lung, and skin cancer rates also
were compared separately for 201 male
and 34 female glassblowers and non-
glassblowers.
Case-control design.
Cases: 344 primary liver cancer deaths
reported to the Finnish Cancer Registry
in 1976-1978 or 1981.
Controls: registry-reported stomach
cancer (476) or myocardial infarction
(385) deaths in the same hospitals,
frequency matched by age and gender.
No specific Pb exposure indices
were computed. Analyses did
examine glass workers as a
whole and then glassblowers
specifically, which comprised
the group at highest risk for Pb
exposure.
Questionnaires regarding job
history and personal habits were
sent to the closest available
relative.
U.K. based job-exposure matrix
was used to rate potential
exposure to 50 substances,
including Pb compounds
Industrial hygienists also
inspected histories to identify
those with highly probable
exposure and rate it as high,
low, or moderate (<10 yrs high
or 10+ yrs low exposure).
SIR (95% CI); number of cases
Lung cancer, all glass workers:
Male 1.3(1.0, 1.7); 62
Female 1.1 (0.5, 2.3); 7
Lung cancer risk showed no specificity for glassblowers.
Skin cancer, males and females combined:
All workers 1.5 (0.8,2.7); 11 (little difference between genders)
Glassblowers 6.2 (1.3, 18.3); 3
Stomach cancer, males and females combined:
Glassblowers 2.3 (0.9, 5.0); 6
No increase in other glass workers
No increase in cancers of other sites. No control for smoking
or occupational coexposures.
OR (95% CI)
52 workers with potential Pb exposure'.
0.91(0.65,1.29)
11 women with potential Pb exposure'.
1.84(0.83,4.06)
5 men with probable moderate exposure:
2.28 (0.68, 7.67)
None had high exposure and only 1 had low exposure, whereas
4 controls had high exposure.
Female controls appeared to underreport their job history.
Most controls had stomach cancer, which if caused by Pb would bias
results toward the null. Few subjects were rated as having a high
probability of exposure.
-------
Table AX6-7.4 (cont'd). Other Studies of Lead Exposure and Cancer
Reference, Study
Location, and
Period
Study Description
Pb Measurement
Findings and Interpretation
Europe (cont'd)
Wesseling et al.
(2002)
Finland
1971-1995
X
Pesch et al. (2000)
Germany
1991-1995
Cohort design, but at ecologic level.
413,877 Finnish women with occupation
reported in 1970 linked to Finnish Cancer
Registry to identify new cases of brain or
nervous system cancer arising form
1971 to 1995.
Poisson regression was used to calculate SIRs
for exposed vs. unexposed groups.
Case-control design.
Cases: 935 renal-cell cancer patients in five
German areas.
Controls: 4,298 region, age, and gender-
matched controls from the surrounding
population.
ORs were adjusted for age, center,
and smoking.
Reported occupation in 1970 was
used to classify women into job
titles. Potential exposure for
each job title was estimated
using a job matrix after
excluding women in the highest
social classes or in farming. Pb
and 23 other workplace agents
examined. Rates for each job
title were calculated, and SIRs
for low and medium/high
exposure calculated (avg
estimated blood Pb of
0.3 umol/L served as cut point
between low and medium/high
exposure).
Job histories were used to
categorize exposure to cadmium,
Pb, and other potential as low vs.
medium, high, or substantial.
Separate exposure estimates
were obtained from British and
from German-derived job-
exposure matrices.
SIR (95% CI), unadjusted for other metals
Low exposure: 1.25 (0.68, 1.81)
Medium/high exposure: 1.33 (0.90, 1.96)
SIR (95% CI), adjusted for cadmium and nickel exposure
Low exposure: 1.18 (0.88,1.59)
Medium/high exposure: 1.24(0.77, 1.98)
All results were adjusted for birth cohort, period of diagnosis, and
job turnover rate.
Incidence, exposure to Pb, and potential confounding factors were
calculated at the level of job title rather than at the individual
level. Exposure and other estimates were based on data for all
workers pooled, not for women specifically. Job classification
was based on a single yr, not lifetime job history.
OR (95% CI); number of cases
Substantial Pb exposure based on British matrix:
Male 1.5 (1.0, 2.3); 29
Female 2.6(1.2,5.5); 11
Substantial Pb exposure based on British matrix:
Male 1.3 (0.9, 2.0); 30
Female not reported
Analyses controlled for smoking. No control for exposure to
other occupational agents.
-------
Table AX6-7.4 (cont'd). Other Studies of Lead Exposure and Cancer
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings and Interpretation
X
to
o
o
Europe (cont'd)
Kandiloris et al. (1997)
Greece
Cordioli et al. (1987)
Italy
1953-1967
Coccoetal. (1994a)
(expansion of Carta
etal., 1994).
Sardinia
1931-1992
Case-control design.
Cases: 26 patients with histologically
confirmed laryngeal carcinoma and no
history of Pb exposure or toxicity.
Controls: 53 patients with similar
demographic profiles and no history of
cancer from the same hospital.
Cohort design.
468 Italian glass workers employed for
at least one yr between 1953 and 1967.
Mortality among workers was tracked
and cause of death was determined for
deceased workers. Standardized
mortality ratios were computed for
workers vs. national population
counterparts.
Cohort design.
1,741 male Sardinian Pb and zinc miners
from two mines employed at least one yr
between 1931 and 1971.
Mortality traced through 1992 to
determine cause of death.
Mortality among miners was compared
with age- and calendar-yr-specific
regional rates to compute an SMR.
Blood Pb levels and ALAD activity were
measured.
Workers producing low-quality glass
containers were classified as Pb-exposed.
All miners were considered to be exposed
toPb.
Blood Pb levels were similar, but ALAD activity was
significantly lower in cases than controls (Mean 50.79 U/L
vs. 59.76 U/L, p < 0.01). No control for other risk factors.
Potential distortion by effects of disease on Pb and/or
ALAD parameters.)
SMR (95% CI); number of deaths
All cancer 1.3 (0.8, 1.8); 28
Lung 2.1(1.1,3.6); 13
Laryngeal 4.5 (1.2, 11.4); 4
SMR (95% CI); number of deaths
All cancer 0.94 (0.83, 1.05); 293
Prostate
Bladder
Kidney
Nervous system
Oral
Lymphohemopoietic
Digestive
1.21; 16
1.15; 17
1.28; 7
1.17; 8
0.61; 8
0.91; 21
0.83; 86
3.67 (1.35, 7.98); 6
Peritoneum
No other p< 0.05.
No control for smoking or exposure to silica, radon, or
other exposures.
-------
Table AX6-7.4 (cont'd). Other Studies of Lead Exposure and Cancer
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings and Interpretation
X
to
o
Europe (cont'd)
Coccoetal. (1994b)
Sardinia
1951-1988
Coccoetal. (1996)
Sardinia
1973-1992
Cohort design.
526 female Sardinian Pb and
zinc miners from the same
mines as in Cocco et al.
(1994a).
Mortality traced through 1992
to determine cause of death.
Mortality among miners was
compared with age- and
calendar-yr-specific regional
rates to compute an SMR.
Cohort design.
1,222 male Sardinian Pb and
zinc smelter workers whose
G6PD phenotypes had been
determined, employed any
time from 1973-1990.
Mortality traced through 1992
to determine cause of death.
Mortality was compared with
regional rates.
All miners were considered to be
exposed to Pb.
All workers were considered to be
exposed to Pb.
Workers were subdivided into
6PD-normal and -deficient groups.
SMR (95% CI)
Liver 5.02(1.62,11.70)
Lung 2.32 (0.85, 5.05)
Other cancers showed nonsignificantly reduced rates.
No control for smoking or exposure to silica, radon, or other exposures.
Low statistical power due to small population and paucity of cancers
during follow-up.
All cancer and lung cancer: mortality lower than expected
Stomach cancer: mortality higher than expected
G6PD deficiency had little apparent effect on mortality: cancer and all-
cause mortality was slightly lower among G6PD-deficient workers than
among G6PD-normal workers.
No control for smoking or exposure to other agents in the smelter.
Healthy worker bias-evident (all-cause mortality 31 observed vs. 44
expected), brief follow-up, low proportion of older ages (mean age at
entry 30, avg follow-up less than 11 yrs), no cumulative exposure data.
-------
Table AX6-7.4 (cont'd). Other Studies of Lead Exposure and Cancer
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings and Interpretation
X
to
o
to
Europe (cont'd)
Coccoetal. (1997)
Sardinia
1931-1992
Wingren and Axelson
(1987,1993)
(update of Wingren
and Axelson, 1985,
same basic cohort as in
Wingren and
Englander(1990)
Sweden
1950-1982
Cohort design.
1,388 male production and maintenance
workers employed for at least 1 yr at a
Sardinian Pb and zinc smelter between
June of 1932 and July of 1971.
Mortality was followed up through 1992.
Mortality was compared with age- and
calendar-yr-specific regional rates.
Since regional rates were only available
for 1965 and later, analyses were limited
to this period.
Case-control design.
Source population: 5,498 men aged
45 or older in 11 Swedish parishes,
including 887 glass workers.
Cancer-specific nested case-control
analysis:
Cases: deaths due to stomach, colon,
and lung cancer from 1950-1982
Controls: deaths due to causes other
than cancer or cardiovascular disease
All workers were considered to
be exposed to Pb.
Glass workers were considered
exposed.
Glassblowers also singled out
as workers with higher
exposure potential.
Job history applied to job
matrix to categorize
occupations as low, moderate,
or high Pb exposure.
SMRs vs. regional rates (95% CI); number of deaths
Lung
Stomach
All cancers
Kidney
Bladder
Brain
0.82(0.56, 1.16); 31
0.97(0.53,1.62); 14
0.93(0.78,1.10); 132
1.75 (0.48,4.49); 4
1.45(0.75,2.53); 12
2.17(0.57, 5.57); 4
Kidney cancer showed a significant trend toward increasing risk with
increasing duration of exposure
No significant trends were noted for lung or other cancers
Brain cancer excess was limited to workers employed for 10 yrs or
less.
No control for smoking or exposure to arsenic or other smelter-
related exposures. No data on intensity of exposure.
Strong association of smelter work with pneumoconiosis and other
respiratory disease (SMR = 4.47, 95% CI: 3.37, 5.80); since this
outcome includes silicosis, which is thought to predispose individuals
to lung cancer, some lung cancer deaths may have been missed due to
misclassification of cause of death based on death certificates.
OR (90% CI); number of deaths
All glass workers:
Lung 1.7 (1.1,2.5); 86
Stomach 1.5 (1.1, 2.0); 206
Colon 1.6 (1.0, 2.5); 79
Glassblowers:
Lung 2.3
Stomach 2.6
Colon 3.1
Glassblowers singled out from glass workers as a whole thus showed
higher estimated risk. ORs for high or moderate vs. low exposure
showed no consistent increase for lung or stomach cancer, however,
although they did show mild upward trend for colon cancer.
No control for smoking or other occupational exposures.
-------
Table AX6-7.4 (cont'd). Other Studies of Lead Exposure and Cancer
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings and Interpretation
X
to
o
Europe (cont'd)
Wingren and
Englander(1990)
Sweden
1964-1985
(same population as in
case-control analyses
of Wingren and
Axelson 1985,1987,
1993)
Dingwall-Fordyce
and Lane (1963)
U.K.
1925-1962
Malcolm and Barnett
(1982) (follow-up of
Dingwall-Fordyce and
Lane, 1963)
U.K.
1925-1976
Cohort design.
625 Swedish glass workers employed
for at least 1 mo between 1964
and 1985.
Mortality was compared with national
rates.
Cohort design.
425 male employees drawing pensions
from U.K. battery plants.
Standardized mortality for employees
vs. national population counterparts.
Cohort design.
1,898 Pb-acid battery workers.
Mortality was traced for the Pb-acid
battery workers to determine cause of
death. The proportion of deaths due to
cancer (all types and major
subcategories) among the worker
population was compared to that seen in
corresponding members of the general
population, yielding a PMR.
Workers from areas with
airborne Pb levels up to 0.110
mg/m3 were classified as
exposed.
Battery plant workers were
assumed to be exposed, and
their mortality compared to that
of like age and gender in the
U.K. population as a whole.
Urinary Pb excretion was also
used to categorize workers by
estimated exposure (none, light,
or heavy): 80 lightly and 187
heavily (at least 100 ng/L)
exposed.
Job histories were reviewed to
classify workers' Pb exposure
as high, medium, or none.
SMR (95% CI)
Phatyngeal: 9.9(1.2,36.1)
Lung: 1.4(0.5,3.1)
Colon: nonsignificant
SMR (95% CI); number observed deaths
All cancer: 1.2 (0.8, 1.7); 267
No consistent increase in SMRs across categories of increasing Pb
exposure.
Limitations: No cancer site-specific analyses. No control for
potential confounders including smoking and exposure to arsenic or
other metals.
Proportionate mortality ratio (PMR)
All cancers:
1.15 (136 deaths), p> 0.05
By exposure:
None
Medium
High
1.02
1.06
1.30
No significant excesses for individual cancer sites except for
digestive cancer PMR of 1.67, p < 0.01, among nonexposed workers.
The difference in exposure for the high and medium exposure groups
narrowed greatly over the follow-up, thus complicating interpretation
of dose-response patterns. No control for smoking or occupational
exposure to other carcinogens.
-------
Table AX6-7.4 (cont'd). Other Studies of Lead Exposure and Cancer
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings and Interpretation
Europe (cont'd)
Ades and Kazantzis
(1988)
U.K.
1943-1982
X
to
o
Cohort design.
4,393 male zinc, Pb, and cadmium smelter
workers.
(Workers born after 1939 or who had worked
less than one yr at the facility were excluded.)
Workers followed up for mortality.
Nested case-control analysis also conducted to
quantitatively assessed cadmium and,
secondarily, arsenic, Pb, and other metal
exposures among 174 cases.
Job histories were used to quantify
cadmium exposure and assign
ordinal ranks for exposure to Pb and
other metals.
Standardized lung cancer mortality
ratio computed for workers vs.
national rates.
SMR (95% CI); number of deaths
Cohort:
Lung 1.25(1.07,1.44); 174
Increased significantly with duration of employment.
Nested case-control analyses did not implicate any
department or process, nor did cadmium, zinc, sulfur dioxide,
or dust exposure account for the observed increase.
Cumulative exposure to Pb and to arsenic both showed
positive associations with lung cancer, but the relative
importance of these two exposures could not be determined.
Cadmium exposure did not account for the elevated SMR,
but analyses could not control for exposure, and were not
adjusted for smoking.
Asia
Huetal. (1998)
China
1989-1996
Case-control design.
Cases: 218 patients with histologically-
confirmed primary gliomas occurring during
1989-1996 at 6 Chinese hospitals.
Controls: 436 patients with non-neurological,
nonmalignant disease, matched by age, gender,
and residence from the same hospitals
(excluding one cancer-only center).
Patients were interviewed, and those
with factory or farm occupations
were further interviewed to identify
exposure to Pb (or other potentially
toxic substances).
Occupational exposure to Pb'.
Not reported for any glioma patients, but was reported for
4 controls.
No control for exposure to other occupational or
environmental agents.
-------
Table AX6-7.4 (cont'd). Other Studies of Lead Exposure and Cancer
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings and Interpretation
Asia (cont'd)
Huetal. (1999)
China
1989-1996
X
to
o
Shuklaetal. (1998)
India
1995-1996
Case-control design.
Cases: 383 patients with histologically
confirmed primary meningiomas
occurring during 1989-1996 at 6 Chinese
hospitals.
Controls: 366 patients with non-
neurological, nonmalignant disease
matched by age, gender, and residence
from the same hospitals (excluding one
cancer-only center).
Case-control design.
Cases: 38 patients with newly
diagnosed, histologically confirmed gall
bladder cancer cases assembled from a
surgical unit.
Controls: 58 patients with gall stones
diagnosed at the same surgical unit,
matched on geographic area.
Mean bile Pb content was compared
between cases and controls.
Patients were interviewed, and
those with factory or farm
occupations were further
interviewed to identify
exposure to Pb (or other
potentially toxic substances).
Heavy metal content was
measured in bile drawn from
the gall bladder at time of
OR (95% CI); number of cases
Occupational exposure to Pb:
Male: 7.20 (1.00, 51.72); 6
Female: 5.69 (1.39, 23.39); 10
Results were adjusted for income, education, and fruit and vegetable
intake, plus cigarette pack-yrs for the women. No control for
exposure to additional metals or other occupational exposures.
Bile Pb content: mean (SE)
Gall bladder cancer: 58.38 mg/L (1.76)
Gallstones: 3.99 mg/L (0.43)
Cadmium and chromium levels also were elevated in cancer patients,
but less than Pb. No control for smoking or any other risk factors.
-------
ANNEX TABLES AX6-8
AX6-206
-------
Table AX6-8.1. Effects of Lead on Immune Function in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States
X
to
o
Joseph et al. (2005)
SE Michigan
(1994-1998)
Sarasua et al. (2000)
ATSDR Multi-site
Study: Granite City,
IL, Galena, KA; Joplin,
MO; Palmerton, PA
1991
Rabinowtiz et al. (1990)
Boston, MA
1979-1987
Design: prospective (1 yr following 3-yr
baseline recruitment)
Subjects: children (n = 4634), age range
0.4-3.Oyr
Outcome measures: asthma prevalence and
incidence.
Analysis: multivariate proportional hazard
model (Cox)
Design: cross-sectional
Subjects: children and adults (n = 2036)
Outcome measures: total lymphocyte count,
lymphocyte phenotype abundance, serum
IgA, IgG, and IgM.
Analysis: multivariate linear regression
Design: cross-sectional
Subjects: infants/children (n= 1768)
Outcome measures: incidence of illness in
children was solicited from parents by
questionnaire.
Analysis: relative risk of illness estimated
from incidence ratios, highest: combined
lower blood Pb deciles, without adjustment
for covariates or confounders.
Blood Pb (ug/dL) mean
(SD, median, %>10):
5.5(4.0,4.0,8.6%)
Blood Pb (ug/dL) mean
(SD, 5th-95th %):
6-35 mo: 7.0
(16,1.1-16.1)
36-71 mo: 6.0
(4.3,1.6-14.1)
6-1 Syr: 4.0
(2.8,1.1-9.2)
16-75 yr: 4.3
(2.9,1.0-9.9)
Cord blood Pb (ug/dL)
~90th%: 10
Shed tooth Pb (ug/g) ~90th
%: 5
Covariate-adjusted hazards ratio (HR, asthma incidence <5 ug/dL
compared to 35 or 310 ug ML):
Caucasian: 35 ug/dL, 1.4 (95% CI: 0.7, 2.9)
310 ug/dL, 1.1(95%CI: 0.2,8.4)
African American: 35 ug/dL, 1.0 (95% CI: 0.8,1.3)
310 ug/dL, 0.9 (95% CI: 0.5, 1.4)
HR for asthma incidence in African Americans, compared to
Caucasians (<5 ug/dL):
<5^ig/dL: 1.6(95%CI: 1.4,2.0)
35 ug/dL: 1.4(95%CI: 1.2,1.6)
310 ug/dL: 2.1(95%CI: 1.2,3.6)
Covariates included: avg annual income, birth weight, and gender.
Significant association (p < 0.05) between increasing blood Pb and
increasing serum IgA, IgG, IgM, and B-cell abundance (%, number),
and decreasing T-cell abundance (%) in 6-35 mo age category;
adjusted for age, sex, and study site. Comparison of outcome means
across blood Pb quartiles (1st quartile as reference, [+], higher, [-]
lower): [+] lymphocyte count (4th quartile, p = 0.02), T-cell count
(4th quartile, p = 0.09), B-cell count (4th quartile, p < 0.01), B-cell
% (4th quartile, p = 0.09).
Relative risk (unadjusted) was elevated for the following illness
categories: severe incidence of ear infection, 1.2 (95% CI: 1.0, 1.4),
other respiratory illness, 1.5 (95% CI: 1.0, 2.3), school absence for
illness other than cold or flu, 1.3 (95% CI: 1.0, 1.5).
-------
Table AX6-8.1 (cont'd). Effects of Lead on Immune Function in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States (cont'd)
Lutzetal. (1999)
Springfield-Green Co,
MO
NR
Design: cross-sectional
Subjects: children (n = 279; age range 9
mo-6 yr)
Outcome measures: differential blood cell
counts; lymphocyte phenotype abundance
(%); and serum IL-4, soluble CD25, CD27,
IgE and IgG (Rubella).
Analysis: nonparametric comparison of
outcome measures (adjusted for age) for
blood Pb categories, correlation
Blood Pb (ug/dL) range:
Blood Pb categories:
<10 ug/dL, 10-14 ug/dL,
15-1 9 ug/dL, 20^15 ug/dL
Significant association (p < 0.05) between increasing blood Pb
(categorical) and increasing serum IgE levels, after adjusting for age.
X
to
o
oo
Europe
Annesi-Maesano et al.
(2003)
France
1985,1992
Karmaus et al. (2005)
Germany
1994-1997
Design: cross-sectional
Subjects: mother/newborn pairs (n = 374),
mean age 30 yr
Outcome measures: maternal venous and
newborn cord serum IgE levels
Analysis: multivariate linear regression,
ANOVA
Design: cross-sectional
Subjects: children (n = 331, 57% male), age
7-8 yrs (96%), 9-10 yrs (4%)
Outcome measures: differential blood cell
count; lymphocyte phenotype abundance;
and serum IgA, IgE, IgG, IgM
Analysis: multivariate linear regression
Blood Pb (ug/dL) mean
(SD):
Infant cord: 67.3(47.8)
Maternal: 96.4(57.7)
Hair Pb (ppm) mean (SD):
Infant: 1.38(1.26)
Maternal: 5.16(6.08)
Blood Pb (ug/dL) mean
(95% CI):
Males: 2.5(1.1,4.4)
Females (2.8 (1.5, 4.8)
Blood Pb quartile ranges:
<2.2 (n = 82)
2.2-2.8 (n= 81)
2.8-3.4 (n= 86)
>3.4(n=82)
Significant (p < 0.0001) association between increasing infant hair
Pb and infant cord serum IgE levels.
Although medical histories were taken to identify potential IgE risk
factors (asthma, allergies) and "confounders" (e.g., smoking), these
do not appear to have been quantitatively integrated into the
regression models. Allergy status and blood levels were reportedly
unrelated to load biomarkers or serum IgE (basis for conclusion not
reported).
Significant association between blood Pb (p < 0.05) and serum IgE
(not monotonic with quartile range). Comparison of adjusted mean
outcomes (p#0.05) across blood Pb quartiles (1st quartile as
reference, [+], higher, [-] lower): [-] CD3+ T-cells (2nd quartile),
[-] C3+CD8+ T-cells (2nd quartile), [+] C3+CD5+CD19+B-cells (2nd
quartile).
Covariates retained: age, sex, environmental exposure to tobacco
smoke, infections (in last 12 mo), serum cholesterol, and
triglycerides.
-------
Table AX6-8.1 (cont'd). Effects of Lead on Immune Function in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Reigart and Graber
(1976)
NR
NR
Design: clinical
Subjects: children (n = 19), ages 4-6 yrs
Outcome measures: serum IgA, IgG, IgM,
total complement and C-3, before and after
immunization with tetanus toxoid
Analysis: none; presentation of prevalence
of clinically low, normal, and high values of
outcome measures
Blood Pb (ng/dL) mean
(range):
High: >40(n=12): 45.3
(41-51)
Low: #30(n=7): 22.6
(14-30)
No apparent difference in prevalence of abnormal values for serum
immunoglobulin or complement (no statistical analysis applied).
Wagnerova et al. (1986)
Czech
NR
X
to
o
VO
Design: longitudinal cohort (repeated
measures for 2-yrs)
Subjects: children (n = 92, 38 females) ages
11-13 yrs residing near a smelter; reference
group (n = 67, 36 females), ages 11-13 yrs
Outcome measures: serum IgA, IgE, IgG,
IgM
Analysis: comparison of outcome measures
and between exposed and reference groups,
stratified sex and season of sampling
Blood Pb (ng/dL) mean:
Pb: -23^2
Reference: —5-22
Significant (p NR, statistic NR) lower serum IgE and IgM levels in
exposed group compared to reference group.
Latin America
Pineda-Zavaleta et al.
(2004)
Mexico
NR
Design: cross-sectional
Subjects: children (n = 30 female, 35 male)
ages 6-11 yrs, residing near smelter
Outcome measures: mitogen- (PHA) and
cytokine- (IFN-Q induced nitric oxide and
superoxide production in lymphocytes
Analysis: multivariate linear regression
Blood Pb (ng/dL) mean
(range) for 3 schools:
l(n = 21): 7.0(3.5-25.3)
2(n = 21): 20.6
(10.8^9.2)
3(n = 23): 30.4
(10.3^7.5)
Significant (p = 0.036) association between increasing blood Pb
concentration and covariate adjusted decreasing nitric oxide
production in PHA-activated lymphocytes (3 = -0.00089 [95% CI:
-0.0017, -0.00005]).
Significant (p = 0.034) association between increasing blood Pb
concentration and covariate adjusted increasing super oxide
production in IFN-(-activated lymphocytes (3 = -0.00389 [95% CI:
0.00031, 0.00748]). Covariates considered included age, sex,
allergies, and blood arsenic (age, sex, and blood arsenic were
retained).
Significant effect of sex on associations, significant blood Pb-arsenic
interaction.
Covariates considered included age, sex, allergies, urinary arsenic
(age, sex, and urinary arsenic were retained).
-------
Table AX6-8.1 (cont'd). Effects of Lead on Immune Function in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia
Sunetal. (2003); Zhao
et al. (2004)
China
NR
Design: cross-sectional
Subjects: children (n = 73) age 3-6 yrs
Outcome measures: serum IgE, IgG, IgM;
lymphocyte phenotype abundance
Analysis: Nonparametric comparisons of
outcome measures stratified by blood Pb
Blood Pb (ng/dL) mean
(SD, range) (n = 217):
9.5(5.6,2.6^3.7)
Females: significantly higher (p < 0.05) IgE levels in high blood Pb
category (310 ng/dL, n = 16) compared to low category (<10 ng/dL,
n = 17), and significantly lower IgG and IgM levels. A multivariate
analysis of association between blood Pb and IgE was noted but not
described in sufficient detail to evaluate.
All children: significantly lower (p < 0.05) CD3+CD4+ (%),
CD3+CD8+ (%), CD4+CD8+ (%) in high blood Pb (310 |ig/dL,
n = 38) compared to low blood Pb (10 ng/dL, n = 35) group.
X
to
o
-------
Table AX6-8.2. Effects of Lead on Immune Function in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States
X
to
Pinkertonetal. (1998)
U.S.
NR
Sarasua et al. (2000)
ATSDR Multi-site
Study: Granite City,
IL, Galena, KA; Joplin,
MO; Palmerton, PA
1991
Design: cross-sectional cohort
Subjects: adult male smelter workers
(n = 145, mean age 32.9V8.6); reference
group, male hardware workers (n = 84, mean
age30.1V9.3)
Outcome measures: differential blood cell
counts; lymphocyte phenotype abundance;
serum IgA, IgG, IgM; salivary IgA;
lymphocyte proliferation (tetanus toxoid)
Analysis: multivariate logistic regression
with comparison of adjusted outcome
measures between exposed and nonexposed
groups
Design: cross-sectional cohort
Subjects: children and adults (n = 2036)
Outcome measures: total lymphocyte count,
lymphocyte phenotype abundance, serum
IgA, IgG, and IgM
Analysis: multivariate linear regression
Blood Pb (ug/dL) median
(range)
Pb: 39(15-55)
Reference: <2 (<2-12)
Blood Pb (ug/dL) mean
(SD, 5th-95th %):
6-35 mo: 7.0
(16,1.1-16.1)
36-71 mo: 6.0
(4.3,1.6-14.1)
6-1 Syr: 4.0
(2.8,1.1-9.2)
16-75 yr: 4.3
(2.9,1.0-9.9)
Covariate-adjusted outcomes in Pb workers that were significantly
(p < 0.05) different from nonexposed ([+], higher, [-] lower): [-] %
monocytes, [-] % CD4+CD8+ cells, [-] % CD8+CD56+ cells.
Significant (p < 0.05) adjusted regression coefficients in exposed
group for independent variable:
blood Pb: [+] CD19+ B-cells (%, no)
time-integrated blood Pb: [-] serum IgG, [+] CD4+CD45RA+ cells
(%, number)
Covariates considered in the analysis included age, race, smoking
habits, alcohol consumption, marijuana use, work shift, and various
factors that might stimulate or suppress the immune system (e.g.,
exposure to direct sunlight, sleep hrs, allergy, flu or cold symptoms).
Covariates retained in the final model were age, race, work shift,
smoking habits.
No significant association (p < 0.05) between blood Pb and
outcomes in adults (age 316 yr).
Covariates retained: age, sex, cigarette smoking, and study site.
-------
Table AX6-8.2 (cont'd). Effects of Lead on Immune Function in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States (cont'd)
Fischbein et al. (1993)
New York
NR
Design: cross-sectional cohort
Subjects: adult firearms instructors (n = 51),
mean age 48 yr; age-matched reference
subjects (n = 36).
Outcome measures: lymphocyte phenotype
abundance, lymphocyte proliferation (PHA,
PWM, Staph. aureus)
Analysis: comparison of outcome measures
between reference and blood Pb categories;
multivariate linear regression
Blood Pb (ng/dL) mean
(SD)
Pb high (325): 31.4(4.3)
Pblow(<25): 14.6(4.6)
Reference: <10
X
ON
to
to
Outcomes in Pb workers that were significantly (p < 0.05) different
from reference group ([+], higher, [-] lower):
[-] CD+3 cells (%, number), [-] CD4+ cells (%, number), [-]
CD4+CD8+ cells (number), [-] HLA-DR cells (number), [+] CD20+
cells (%, number), [-] mitogen (PHA)-induced lymphocyte
proliferation, [-] mitogen (PWM)-induced lymphocyte proliferation;
[-] lymphocyte response in mixed-lymphocyte culture. No effect on
antigen (Staph. aureus}-induced lymphocyte proliferation.
Significant (p < 0.05) association between increasing blood Pb and
decreasing abundance of CD4+ phenotypes (%), and decreasing
lymphocyte proliferative response in mixed lymphocyte cultures.
Covariates retained: age, sex, smoking habits, and duration of
exposure.
Europe
Bergeret et al. (1990)
France
NR
Design: cross-sectional cohort
Subjects: adult battery smelting workers
(n = 34), mean age 40 yr; reference subjects
(n = 34), matched for age, sex, ethnic origin,
smoking and alcohol consumption habits,
intake of antibiotics, andNSAIDs
Outcome measures: PMN chemotaxis
(FMLP); PMN phagocytosis (opsonized
zymosan)
Analysis: comparison of outcome measures
between worker and reference groups
Blood Pb (ng/dL) mean
(SD):
Pb: 70.6(18)
Reference: 9.0(4.3)
Significantly (p < 0.05) lower PMN chemotactic response (index)
and phagocytic response in Pb workers.
-------
Table AX6-8.2 (cont'd). Effects of Lead on Immune Function in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Ewers etal. (1982)
Germany
NR
X
K>
OJ
Cosciaetal. (1987)
Italy
NR
Governaetal. (1987)
Italy
NR
Design: cross-sectional cohort
Subjects: adult male battery manufacture or
smelter workers (n = 72), mean age 36.4 yr
(16-58); reference workers (n = 53), mean
age 34.8 yr (21-54)
Outcome measures: serum IgA, IgG, IgM,
C3; saliva IgA
Analysis: parametric and nonparametric
comparison of outcome measures between
Pb workers and reference subjects; linear
regression
Design: cross-sectional cohort
Subjects: adult Pb workers (n = 32, 2
female), mean age 42.8 yr (SD 11.5);
reference subjects (n = 25), mean age 38.6 yr
(SD 13.3)
Outcome measures: serum IgA, IgG, IgM,
C3-C4; lymphocyte phenotype abundance
Analysis: parametric comparison of
outcome measures between worker and
reference groups
Design: cross-sectional cohort
Subjects: adult male battery manufacture
workers (n = 9), mean age 38.4 yr (SD 13.7);
age-matched reference subjects (n = 18)
Outcome measures: PMN chemotaxis
(zymosan-activated serum)
Analysis: parametric comparison of
outcome measures between worker and
reference groups, correlation
Blood Pb (ug/dL) mean
(range):
Pb: 55.4.0(18.6-85.2)
Reference: 12.0 (6.6-20.:
Blood Pb (ug/dL) mean
(SD):
Pb: 62.3(21.6)
Reference: NR
Blood Pb (ug/dL) mean
(SD):
Pb: 63.2(8.2)
Reference: 19.2(6.4)
Significantly (p < 0.05) lower serum IgM, lower salivary IgA in Pb
workers compared to reference group.
Outcomes in Pb workers that were significantly (p < 0.05) different
from reference group ([+], higher, [-] lower): [-] serum IgM, [+]
serum C4, [+] lymphocyte abundance (%), [-] T-cell abundance (%,
number, E-rosette forming cells), [+] B-cell abundance (%,number,
immunoglobulin-bearing cells), [+] CD8+ cell abundance (number).
Significantly (p < 0.05) lower PMN chemotactic response to
zymosan activated serum. Effect magnitude was not correlated with
blood Pb.
-------
Table AX6-8.2 (cont'd). Effects of Lead on Immune Function in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
X
K>
J^.
Europe (cont'd)
Valentino etal. (1991)
Italy
NR
Kimberetal. (1986)
UK
NR
Design: cross-sectional cohort
Subjects: adult male Pb scrap refining
workers (n = 10), mean age 41.1 yr(SD7.3,
range 28-54); age-matched reference
subjects (n= 10)
Outcome measures: PMN chemotaxis (C5 or
FMLP) and phagocytosis (FMLP)
Analysis: comparison of outcome measures
between worker and reference groups,
correlation
Design: cross-sectional cohort
Subjects: adult male TEL manufacture
workers (n = 39) mean age: 45.1yr;and
age-matched reference subjects (n = 21);
mean age 32.2 yr
Outcome measures: serum IgA, IgG, IgM;
mitogen (PHA)-induced
lymphoblastogenesis; and NK cell
cytotoxicity
Analysis: comparison of outcome measures
for exposed and reference groups
Blood Pb (ug/dL) mean
(SD, range):
Pb: 33.2(5.6,25^12)
Reference: 12.6 (2.5, 8.9-
18)
Significantly (p < 0.002) lower PMN chemotactic response to C5 or
FMLP and higher stimulated production of LT (leukotriene)B4 in Pb
workers compared to reference group. Effect magnitude correlated
with blood Pb. No effect on phagocytic activity.
Blood Pb (ug/dL) mean
(SD, range):
Pb: 38.4(5.6,25-53)
Reference: 11.8(2.2,8-
17)
No significant (p < 0.05) differences in outcomes between exposed
and reference groups.
Latin America
Queiroz etal. (1993)
Brazil
NR
Design: cross-sectional cohort
Subjects: adult male battery manufacture
workers (n = 39), mean age 33.9 yr (SD 12.1,
range 18-56); reference subjects (n = 39)
matched by age and race
Outcome measures: PMN chemotaxis
(endotoxin LPS); phagocytic (endotoxin
LPS) respiratory burst activity (NBT
reduction)
Analysis: nonparametric comparison of
outcome measures between worker and
reference groups
Blood Pb (ug/dL) range:
Pb: 14.8-91.4 (>30,
n=52)
Reference: <10
Significantly (p < 0.001) lower chemotactic activity of PMNs, and
lower phagocytic respiratory burst, in Pb workers relative to
reference group.
-------
Table AX6-8.2 (cont'd). Effects of Lead on Immune Function in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Latin America (cont'd)
Queirozetal. (1994a)
Brazil
NR
X
K>
(^
Queirozetal. (1994b)
Brazil
NR
Design: cross-sectional cohort
Subjects: adult male battery manufacture
workers (n = 60), mean age 33.9 yr (range
18-56); reference subjects (n = 49) matched
by age and race
Outcome measures: PMN phagocytic/lytic
activity (opsonized yeast)
Analysis: nonparametric comparison of
outcome measures between worker and
reference groups
Design: cross-sectional cohort
Subjects: adult male battery manufacture
workers (n = 33), mean age 32.4 yr (range
18-56); reference subjects (n = 20) matched
by age and race
Outcome measures: serum IgA, IgG, IgM;
mitogen (PHA)-induced lymphocyte
proliferation
Analysis: parametric comparison of
outcome measures between worker and
reference groups
Blood Pb (ug/dL) range:
Pb: 14.8-91.4 (>30,
n = 27)
Reference: <10
Significantly (p < 0.001) lower lytic activity of PMNs in Pb workers
relative to reference group.
Blood Pb (ug/dL) range:
Pb: 12.0-80.0 (>30,
n = 27)
Reference: <10
No significant difference in outcomes (p < NR; SD of Pb worker and
reference groups overlap) between Pb workers and reference group.
Asia
Kuo etal. (2001) Design: cross-sectional cohort
China Subjects: adult battery manufacture workers
NR (n = 64, 21 female) 14 subj ect aged <40 yr
and 14 subjects aged >50 yr; nonexposed
reference subjects (n = 34, 17 female).
Outcome measures: differential blood cell
counts, lymphocyte phenotype abundance
Analysis: comparison of outcome measures
in exposed and reference groups,
multivariate linear regression
Blood Pb (ug/dL) mean:
Pb: 30
Significantly (p < 0.05) adjusted mean higher monocytes (%,
number), lower B cells (%), lower lymphocytes (number), and lower
granulocytes (number) in Pb workers compared to controls.
Covariates retained: age, gender, and disease status (definition not
reported).
-------
Table AX6-8.2 (cont'd). Effects of Lead on Immune Function in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Mishra et al. (2003)
India
NR
Design: cross-sectional cohort
Subjects: adult males occupationally
exposed to Pb (n = 84), mean age 30 yr;
reference subjects (n = 30), mean age 29 yr
Outcome measures: serum IFN-( level,
mitogen (PHA)-induced lymphocyte
proliferation, NK cell cytotoxicity
Analysis: comparison of outcome measures
between Pb-exposed and reference groups,
correlation
Blood Pb (ng/dL) mean
(SD, range):
3-wheel drivers (n = 30):
6.5(4.7,0.0-17.5)
Battery workers (n = 34):
128.1 (13.2^100.8)
Jewelry makers: 17.8
(18.5,3.1-76.8)
Reference: 4.5 (NR, 1.6-
9.8)
Significantly (p < 0.001) lower lymphocyte proliferative response to
PHA in Pb-exposed groups compared to reference groups, higher
IFN-( production by blood monocytes.
X
Oi
to
Oi
Alomran and
Shleamoon(1988)
Iraq
NR
Cohen etal. (1989)
Israel
NR
Design: cross-sectional cohort
Subjects: adult Pb (oxide) workers (n = 39),
mean age 35.6 yr (9,2, SD); age-matched
reference subjects (n = 19)
Outcome measures: serum IgA, IgG;
mitogen (PHA, Con-A)-induced lymphocyte
proliferation
Analysis: comparison of outcome measures
between Pb workers and reference group
Design: cross-sectional cohort
Subjects: adult male occupationally Pb
exposed (n = 10), age range 22-70; age-
matched reference subjects (n = 10)
Outcome measures: mitogen (Con A, PHA)-
induced-lymphocyte proliferation and T-
suppressor cell proliferation; lymphocyte
phenotype abundance
Analysis: parametric comparison of
outcome means between Pb-exposed and
reference groups
Blood Pb (ng/dL) mean:
Pb: 54-64
Reference: NR
Blood Pb (ng/dL) range:
Exposed: 40-51
Reference: <19
Significantly (p < 0.05) lower lymphocyte proliferative response to
PHA or Con A in Pb workers, compared to reference group.
Significantly (p < 0.02) higher mitogen (Con-A)-induced suppressor
cell activity. No significant (p not reported) effects on abundance of
T-cells (E-rosette-forming cells), OKT+4, OKT+8, or OKT4+/T8+
ratio; mitogen (Con A or PHA)-induced lymphocyte proliferation.
-------
Table AX6-8.2 (cont'd). Effects of Lead on Immune Function in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Sataetal. (1998)
Japan
NR
X
K>
40yr,n=123.
Outcome measures: serum IgE, IL-4, IFN(
Analysis: comparison of outcomes measures
(ANOVA), stratified by age and blood Pb
Blood Pb (ug/dL) mean
(range):
Pb: 19(7-50)
Reference: NR
Blood Pb(ug/dL):
Subject 1: 81 ug/dL at
referral; mean before
EDTA: 45.1(SD16.0);
after chelation: 31.0(9.8)
Subject 2: 68 ug/dL at
referral; mean before
EDTA: 43.3 (SD 14.1);
after chelation: 33.7(7.2)
Blood Pb (ug/dL) mean
(SD):
<30yr: 22.0(10.4)
30-39 yr: 23.0(11.3)
340 yr: 24.1(9.3)
Pb workers vs. reference: significantly (p < 0.05) covariate-adjusted
lower CD3+CD45RO+ (number) and higher CD8+ cells (%).
Significant (p < 0.05) association between exposure (categorical:
yes/no) and lower CD3+CD45RO+cells (number).
Covariates retained: age and cigarette smoking habits.
Blood Pb and outcome measures were sampled prior to and 24 hrs
after 3 CaEDTA treatments (on consecutive days) per wk for 10
wks. Comparison of mean outcome measures assessed before and
after treatments showed significantly (p < 0.05) higher IgA, IgG, and
IgM; and significantly higher CD8+ T-cells and CD57+ NK cells
after treatment in subject 1. Serum IgG levels in subject 1 were
significantly correlated (r = -0.72) with blood Pb concentration.
Significantly higher (p < 0.05) serum IgE levels in blood Pb
category (330 ug/dL) compared to low categories (<10 or 10-
29 ug/dL).
-------
Table AX6-8.2 (cont'd). Effects of Lead on Immune Function in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Unde eretal. (1996);
BalTaran and Unde er
(2000)
Turkey
NR
X
ON
to
oo
Yucesoy etal. (1997a)
Turkey
NR
Yucesoy etal. (1997b)
Turkey
NR
Design: cross-sectional cohort
Subjects: adult male battery manufacture
workers (n = 25), mean age, 33 yr (22-55);
reference subjects (n = 25) mean age 33 yr
(22-56).
Outcome measures: differential blood cell
counts; lymphocyte phenotype abundance;
serum IgA, IgG, IgM, C3, and C4; neutrophil
chemotaxis (zymosan-activated serum); latex
particle-induced neutrophil phagocytic (latex
particles) respiratory burst (NET reduction)
Analysis: nonparametric and parametric
comparisons of outcome measures for
exposed and reference groups
Design: cross-sectional cohort
Subjects: adult male battery manufacture
workers (n = 20), ages 39^8 yr; age-
matched reference subjects (n = 12)
Outcome measures: serum cytokines IL-13,
IL-2, TNFV, IFN-(
Analysis: parametric and nonparametric
comparison of outcome measures in exposed
and reference groups
Design: cross-sectional cohort
Subjects: adult male battery manufacture
workers (n = 50), ages 39^8 yr; age-
matched reference subjects (n = 10)
Outcome measures: lymphocyte phenotype
abundance, NK cell cytotoxicity
Analysis: comparison of outcome measures
in exposed and reference groups
Blood Pb (|ig/dL) mean
(SD):
Pb: 74.8(17.8)
Reference: 16.7(5.0)
Blood Pb (ng/dL) mean
(SE, range):
Pb: 59.4(3.2,42-94)
Reference: 4.8(1.0,2-15)
Blood Pb (|ig/dL) mean
(SE, range):
Pbl(n = 20): 59.4(3.2,
42-94)
Pb2(n=30): 58.4(2.5,
26-81)
Reference: 4.0 (0.4, 2-6)
Workers relative to reference: significantly (p < 0.05) lower serum
IgG, IgM, C3, and C4 levels; lower CD4+ ("T-helper") abundance,
lower neutrophil chemotactic response; no significant difference in
CD20+ (B-cell), CD8+ ("T-suppressor") cell, CD56+(NK) cell
abundance, or particle-induced NK cell respiratory burst.
Significantly (p < 0.05) lower serum IL-13 and IFN-( levels in Pb
workers compared to controls.
Significantly (p < 0.05) lower CD20+ B-cell (%) abundance in Pb
workers compared to controls, no difference in % CD4+ T-cell
abundance.
-------
Table AX6-8.2 (cont'd). Effects of Lead on Immune Function in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Africa
Anetor and Adeniyi
(1998)
Nigeria
NR
Design: cross-sectional cohort
Subjects: adult male "Pb workers" (n = 80),
mean age, 36 yr (21-66) and reference
subjects (n = 50), mean age 37 yr (22-58).
Outcome measures: serum IgA, IgG, and
IgM; lymphocyte count
Analysis: comparison of outcomes measures
in workers and reference group, linear
regression, principal component analysis
Blood Pb (ng/dL) mean
(SE):
Pb: 53.6(0.95)
Reference: 30.4(1.4)
Significantly lower (p < 0.05) serum IgA, IgG, and total blood
lymphocyte levels; significant associations and interactions between
blood Pb and serum total globulins (note high blood Pb levels in
reference).
X
to
VO
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ANNEX TABLES AX6-9
AX6-220
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Table AX6-9.1. Effects of Lead on Biochemical Effects in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States
Marcus and Schwartz
(1987)
U.S.
1976-1980
Design: cross-sectional national survey
(NHANES II)
Subjects: ages 2-6 yr(n= 1677)
Outcome measures: EP, red blood cell count,
mean corpuscular volume, iron status variables
Analysis: nonlinear least squares regression
Blood Pb (ug/dL) range:
6-65
Non-linear regression used to fit kinetic model relating blood Pb
to EP, in strata having low (<14%), medium (14-31%), or high
(>31%) percent transferrin saturation (PST). Parameters in model
included: parameters for total red cell surface area, maximum red
cell Pb concentration, equilibrium concentration ratio for plasma
and whole blood. Blood Pb increase (from 10 ug/dL) predicted to
double EP: 22 (PST < 14%), 24 (PST = 14-31%), 37
(PST > 31%).
X
to
to
Piomellietal. (1982)
New York
1976
Soldin et al. (2003)
Washington DC
2001-2002
Design: cross-sectional
Subjects: children (n = 2002), ages 2-12 yr
Outcome measures: EP
Analysis: linear regression
Design: cross-sectional
Subjects: children (n = 4908, 1812 females),
age range 0-17 yr
Outcome measures: EP
Analysis: locally weighted scatter plot
smoother (LOWESS)
Blood Pb (ug/dL) range:
2-98
Blood Pb(ugML):
Mean (range 1-17 yr):
2.2-3.3
Median (1-17 yr): 3
Range: <1-103
Regression equation relating blood Pb concentration to EP
(log-transformed):
V = 1.099, 3 = 0.016, r = 0.509, p < 0.001
Threshold for increase in EP estimated to be: 15.4 ug/dL (95%
CI: 12.9,18.2)
EP increases as blood Pb concentration increased above
15 mg/dL. A doubling of EP occurred with an increase in blood
Pb concentration of-20 ug/dL (a polynomial expression for EP as
a function of blood Pb (PbB) is:
EP = -0.0015(blood Pb)3 + 0.1854(blood Pb)2 - 2.7554(blood Pb)
+ 30.911 (1-2 = 0.9986)
(derived from data in Table 2 of Soldin et al. (2003)
Europe
Roels and Lauwerys
(1987)
Belgium
1974-1980
Design: cross-sectional
Subjects: children (n = 143), age range
10-1 Syr
Outcome measures: ALAD, urinary ALA, EP
Analysis: linear regression, correlation
Blood Pb (ug/dL) range:
Linear regression for EP (log-transformed) and blood Pb
concentration:
V= 1.321, 3 = 0.025,r = 0.73(n=51)
Linear regression for ALA (log-transformed) and blood Pb
concentration:
V = 0.94, 3 = 0.11, r = 0.54 (n = 37)
Linear regression for ALAD (log-transformed) and blood Pb
concentration:
V = 1.864, 3 = -0.015, r = -0.87 (n = 143)
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Table AX6-9.1 (cont'd). Effects of Lead on Biochemical Effects in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Latin America
Perez-Bravo et al. Design: cross-sectional;
(2004) Subjects: children (n = 93, 43 males), aged 5-
Chile 12 yrs who attended school near a powdered Pb
NR storage facility
Outcome measures: blood Hgb and Hct, ALAD
genotype
Analysis: comparison of outcome measures
between ALAD genotype strata
Blood Pb (ng/dL) mean
(SE):
ALAD1 (n = 84):
13.5(8.7)
ALAD2(n=9): 19.2(9.5)
Mean blood Pb, blood Hgb, and Hct not different between ALAD
genotypes (p = 0.13).
X
to
to
to
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Table AX6-9.2. Effects of Lead on Biochemical Effects in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
X
to
to
Europe
Geimartetal. (1992)
Belgium
NR
Mohammed-Brahim
etal. (1985)
Belgium
NR
Roels and Lauwerys
(1987)
Belgium
1974-1980
Design: cross-sectional cohort
Subjects: adult battery manufacture workers
(n = 98), mean age, 37.7 yr (range 22-55);
reference group (n = 85), mean age 38.8 yr
(24-55)
Outcome measures: blood Hct, blood EP,
urine ALA
Analysis: linear regression
Design: cross-sectional cohort
Subjects: adult smelter and ceramics
manufacture workers (n = 38, 13 females);
reference subjects (n = 100) matched with
worker group by age, sex, and socioeconomic
status.
Outcome measures: blood P5N, EP, ALAD,
R/ALAD (ratio of ALAD before and after
reactivation).
Analysis: comparison of outcome measures
(ANOVA) between Pb workers and reference
group; correlation
Design: cross-sectional
Subjects: adults (n = 75, 36 females)
Outcome measures: ALAD, urinary ALA, EP
Analysis: linear regression, correlation
Blood Pb (ug/dL) mean
(SD, range):
Pb: 51.0(8.0,40-70)
Reference: 20.9
(11.1,4.4-30.0)
Blood Pb (ug/dL) mean
(SD, range):
Pb: 48.5(9.1,27.8-66.6)
Reference: 14.3
(6.7, 5.6-33.6)
Urine Pb (ug/g creatinine)
mean (SD, range):
Pb: 84.0(95.9,21.8-587)
Reference: 10.5
(8.2,1.7-36.9)
Blood Pb (ug/dL) range:
adult males: 10-60
adult females: 7-53
Significant association between increasing blood Pb concentration
and increasing (log) blood EP (V = 0.06, 3 = 0.019, r = 0.87,
p = 0.0001) or (log) urine ALA (V = 0.37, 3 = 0.008, r = 0.64,
p< 0.0001)
(No apparent analysis of covariables)
Significantly lower (p = NR) P5N in Pb workers (males or females,
or combined) compared to corresponding reference groups.
Correlations with blood Pb:
log P5Nr= -0.79 (p < 0.001)
log ALAD r = -0.97 (p = NR)
R/ALAD r = -0.94 (p < 0.001)
logEPr=0.86(p = NR)
Correlations with urine Pb:
log P5Nr=-0.74 (p = NR)
log ALAD r = -0.79 (p = NR)
R/ALAD r = -0.84 (p < 0.001)
logEPr=0.80(p = NR)
Linear regression for EP (log-transformed) and blood Pb
concentration:
adult male (n = 39): V= 1.41, 3 = 0.014, r = 0.74, p< 0.001
adult female (n = 36): V = 1.23, 3 = 0.027, r = 0.81, p < 0.001
Linear regression for ALA (log-transformed) and blood Pb
concentration:
adult male (n = 39): V = 0.37, 3 = 0.006, r = 0.41, p < 0.01
adult female (n = 36): V = 0.15, 3 = 0.015, r = 0.72, p < 0.001
-------
Table 6-9.2 (cont'd). Effects of Lead on Biochemical Effects in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
X
to
to
Europe (cont'd)
Grandjean(1979)
Denmark
NR
Alessioetal. (1976)
Italy
NR
Coccoetal. (1995)
Italy
1990
Design: longitudinal
Subjects: male battery manufacture workers
(n = 19), mean age 32 yr (range 22-A9)
Outcome measures: EP
Analysis: EP and blood Pb for serial
measurements displayed graphically
Design: cross-sectional
Subjects: adult male Pb worker (n = 316), age
range NR
Outcome measures: blood ALAD, EP, urine
ALA, CP
Analysis: linear regression, correlation
Design: longitudinal
Subjects: adult male foundry workers
(n = 40), mean age 25.1 yr (SD 2.1, range
21-28)
Outcome measures: serum total-, HDL- and
LDL-cholesterol, blood Hgb, urine ALA,
erythrocyte G6PD
Analysis: comparison of outcomes between
pre-exposure (at start of employment,
sample 1) and after 172 (range 138-217,
sample 2) days
Blood Pb (ug/dL) median
(range):
Group 1 (n = 5): 47.7
(22.8-53.9)
Group 2 (n= 5): 37.3
(35.2-53.9)
Blood Pb (ug/dL) range:
10-150
Blood Pb (ug/dL) mean
(range):
Sample 1: 10.0(7-15)
Sample 2: 32.7(20-51)
Five subjects (group 1) showed declines in EP with declining
blood Pb (33-58 ug/dL) over a 10-mo period; 5 subjects (group 2)
showed no change in EP with a change in blood Pb concentration
(25-54 ug/dL) over the same period.
Regression relating outcomes to blood Pb concentration:
ALAD (In-transformed) (n = 169): V = 3.73, 3 = -0.031, r = 0.871
ALAU (In-transformed) (n = 316): V = 1.25, 3 = 0.014, r = 0.622
UCP (In-transformed) (n = 252): V = 2.18, 3 = 0.34, r = 0.670
EP (log-transformed (males, n = 95): V = 0.94, 3 = 0.0117
EP (log-transformed (females, n = 93): V = 1.60, 3 = 0.0143
G6PD levels were unrelated to starting blood Pb; however, they
increased in subjects whose blood Pb concentration increased from
<30 ug/dL to >30 ug/dL or decreased from >30 ug/dL to
<30 ug/dL. Increasing exposure duration was significantly
associated with decreasing magnitude of change in G6PD.
Sample 1 <30 ug/dL: 3 = -0.3980 (SE 0.1761), p < 0.05
Sample 1 >30 ug/dL: 3 = -1.3148 (SE 0.3472), p < 0.05
In the >30 ug/dL subgroup, increasing blood Pb was associated
with decreasing magnitude of change of G6PD (3 = -2.0797 [SE
0.7173], p< 0.05).
Serum cholesterol levels were unrelated to blood Pb concentration.
-------
Table 6-9.2 (cont'd). Effects of Lead on Biochemical Effects in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
X
to
to
Europe (cont'd)
Fracasso et al. (2002)
Italy
NR
Hemberg et al. (1970)
Poland
NR
Design: cross-sectional cohort
Subjects: adult battery manufacture workers
(n = 37, 6 females), mean age 41 yr (SD 7);
reference office workers (n = 29, 8 females),
meanage38yr(SD21)
Outcome measures: lymphocyte DNA strand
breaks, ROS, GSH
Analysis: comparison of outcome measures
between Pb workers and reference group
(ANOVA), logistic regression
Design: cross-sectional
Subjects: adult Pb workers (n= 166);
reference group (n = 16)
Outcome measures: blood ALAD
Analysis: regression, correlation
Blood Pb (ug/dL) mean
(SD):
Pb: 39.6(7.6)
Reference: 4.4(8.6)
Blood Pb (ug/dL) range:
5-95
Covariate-adjusted DNA strand breaks were significantly higher in
Pb workers compared to the reference group and significantly
associated with increased blood Pb (p = 0.011).
Covariate-adjusted lymphocyte ROS was significantly higher and
GSH significantly lower in the Pb workers compared to the
reference group. Lower GSH levels were significantly associated
with increasing blood Pb concentration (p = 0.006).
Odds ratios (OR) for DNA strand breaks and lower GSH levels
were significant (Pb workers vs. reference):
DNA strand breaks: OR = 1.069 (95% CI: 1.020, 1.120),
p = 0.005
GSH: OR = 0.634 (95% CI: 0.488, 0.824), p = 0.001
ROS: OR = 1.430 (95% CI: 0.787, 2.596), p = 0.855
Covariates retained: age, alcohol consumption and tobacco
smoking.
Linear regression for blood ALAD (log-transformed) and blood Pb
concentration (n = 158):
V = 2.274, 3 = -0.018, r = -0.90, p < 0.001
Bergdahl et al. (1997)
Sweden
NR
Design: cross-sectional
Subjects: adult smelter worker (n = 89);
reference groups (n = 24)
Outcome measures: blood Pb, erythrocyte
ALAD-bound Pb, ALAD genotype
Analysis: comparison of outcome measures
Blood Pb (ug/dL) range:
0.8-93
Urine Pb (mg/L) range:
1-112
Bone Pb (ug/g) range:
-19-101
No association between ALAD genotype and Pb measures.
Selander and Cramflr
(1970)
Sweden
NR
Design: cross-sectional
Subjects: adult battery manufacture workers
(n=177)
Outcome measures: urine ALA
Analysis: regression, correlation
Blood Pb (ug/dL) range:
6-90
Linear regression for urine ALA (log-transformed) and blood Pb
concentration (n = 150):
V = -1.0985, 3 = 0.0157, r = 0.74
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Table 6-9.2 (cont'd). Effects of Lead on Biochemical Effects in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Wildtetal. (1987)
Sweden
NR
Design: longitudinal
Subjects: adult battery manufacture workers
(n = 234, 37 females) mean age 35 y (range
17-70); reference group (n = 951, 471
females), mean age 39 yr (range 19-67)
Outcome measures: EP
Analysis: analysis of variability over time,
linear regression, correlation
Blood Pb (ug/dL) mean
(range):
Pb: 10-80
Reference:
Male: 11.3(8-27)
Female: 8.5(5-21)
Linear regression for EP (log-transformed) and blood Pb
concentration:
Males (n= 851): V= 1.21, 3 = 0.0148, r= 0.72
Females (n= 139): V = 1.48, 3 = 0.0113, r= 0.56
Asia
X
Oi
to
to
Oi
Hsieh et al. (2000)
China
NR
Jiun and Hsien( 1994)
China
1992
Froometal. (1999)
Israel
1980-1993
Design: cross-sectional
Subjects: Adults in general population
(n = 630, 255 females)
Outcome measures: blood Hgb, Hct, RBC
count, ALAD genotype
Analysis: comparison of outcome measures
between ALAD genotype strata
Design: longitudinal
Subjects: adult male Pb workers (n = 62),
ages NR; reference group (n = 62, 40 females),
agesNR
Outcome measures: plasma MDA
Analysis: comparison of outcome measures
between Pb workers and reference group,
linear regression
Design: longitudinal survey
Subjects: adult male battery manufacturing
workers (n = 94), mean age, 38 yr (SD 9,
range 26-60)
Outcome measures: blood Hgb, blood EP
Analysis: multivariate linear regression
Blood Pb (ug/dL) mean
(SD):
ALADl,l(n=630):
6.5(5.0)
ALAD1,1/2,2 (n= 30):
7.8 (6.0)
Blood Pb (ug/dL) mean
(SD, range):
Pb: 37.2
(12.5, 18.2-76.0)
Reference: 13.4
(7.5,4.8^3.9)
Blood Pb (ug/dL) range of
13-yr individual subject
means:
20-61 ug/dL
Mean blood Pb not different between ALAD genotype strata
(p = 0.17). RBC count, Hgb, Hct not different between ALAD
genotype strata (p = 0.7)
Plasma MDA levels significantly (p < 0.0001) higher (~2x) in Pb
workers whose blood Pb concentration 35 ug/dL compared to
#30 ug/dL. In subjects with blood Pb >35 ug/dL, blood Pb and
plasma MDA were significantly correlated:
blood Pb = 9.584(MDA) + 24.412 (r = 0.85)
Weak (and probably not significant) covariate-adjusted association
between blood Hgb and individual sample blood Pb (3 = -0.0039
[SE 0.0002]), subject avg blood Pb (3 = -0.0027 [SE 0.0036]), or
blood EP (3 = -0.001 [SE 0.0007])
Covariates retained in model were age and smoking habits.
-------
Table 6-9.2 (cont'd). Effects of Lead on Biochemical Effects in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Kristal-Boneh et al.
(1999)
Israel
1994-1995
X
to
to
Solliway et al. (1996)
Israel
NR
Design: cross-sectional cohort
Subjects: adult male battery manufacture
workers (n = 56), mean age 43.1 yr (SD 10.6);
reference group (n = 87), mean age 43.2 yr
(SD 8.3)
Outcome measures: serum total-, HDL-, LDL-
cholesterol, HDL: total ratio, triglycerides
Analysis: comparison of outcome measures
between Pb workers and reference group
(ANOVA), multivariate linear regression
Design: cross-sectional cohort
Subjects: adult male battery manufacture
workers (n = 34), mean age: 44 yr (SD 13);
reference subjects (n = 56), mean age 43 yr
(SD 12); cohorts constructed to have similar
age, ethnic characteristics, socioeconomic
status, education level, and occupation
Outcome measures: urinary ALA, erythrocyte
GSH-peroxidase
Analysis: parametric comparison of outcome
measures between Pb and reference groups,
correlation
Blood Pb (ng/dL) mean
(SD):
Pb: 42.3(14.9)
Reference: 2.7(3.6)
Blood Pb (ng/dL) mean
(SD, range):
Pb: 40.7(9.8,23-63)
Reference: 6.7(2.4,1-13)
Covariate-adjusted serum total-cholesterol (p = 0.016) and HDL-
cholesterol (p = 0.001) levels were significantly higher in Pb
workers compared to reference group. Covariates retained in
ANOVA: age, body mass index, season of sampling, nutritional
variables (dietary fat, cholesterol, calcium intakes), sport activities,
alcohol consumption, cigarette smoking, education, job seniority.
Increasing blood Pb concentration was significantly associated
with covariate-adjusted total cholesterol (3 = 0.130 [SE 0.054],
p = 0.017) and HDL-cholesterol (3 = 0.543 [SE 0.173], p = 0.002).
Covariates retained: age, body mass index. Stepwise inclusion of
other potential confounders had no effect.
Significantly lower mean erythrocyte GSH-peroxidase activity
(p < 0.005) in and higher urinary ALA (p < 0.001) in Pb workers
compared to reference group.
Ito etal. (1985) Design: cross-sectional cohort
Japan Subjects: adult male steel (smelting, casting)
NR workers (n = 712), age range 18-59 yr;
reference (office workers) group (n = 155,
total), age range 40-59 yr
Outcome measures: serum LPO and SOD,
total and HDL-cholesterol, phospholipid
Analysis: comparison of outcome measures
between Pb workers and reference group,
correlation
Blood Pb (ng/dL) range:
Pb: 5-62
Reference: NR
When stratified by age, significantly (p < 0.05) higher serum HDL-
cholesterol and LPO in Pb workers, age range 40^9 yr, compared
to corresponding strata of reference group. Serum lipoperoxide
levels increased as blood Pb increased above 30 ng/dL (p = NR),
SOD appeared to decrease with increasing blood Pb concentration
(p = NR)
-------
Table 6-9.2 (cont'd). Effects of Lead on Biochemical Effects in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Makinoetal. (1997)
Japan
1990-1994
X
to
to
oo
Moritaetal. (1997)
Japan
NR
Oishietal. (1996)
Japan
NR
Design: longitudinal survey
Subjects: adult male pigment or vinyl chloride
stabilizer manufacture workers (n = 1573)
mean age 45 yr
Outcome measures: blood Hgb, Hct,
RBC count
Analysis: parametric comparison of outcome
measures, stratified by blood Pb, linear
regression
Design: cross-sectional cohort
Subjects: male Pb workers (n = 76), mean age
42 yr (range 21-62); reference subjects
(n = 13, 6 females), mean age, males 41 yr
(range 26-52), females 45 yr (range 16-61)
Outcome measures: blood NADS, ALAD
Analysis: comparison of outcome measures
(ANOVA) between blood Pb categories, linear
regression
Design: cross-sectional
Subjects: adult glass and pigment manufacture
workers (n = 418, 165 females), mean age 33
yr (range 18-58); reference workers (n = 227,
89 females), mean age 30 yr (range 17-59)
Outcome measures: plasma ALA, urinary
ALA
Analysis: linear regression, correlation
Blood Pb (ug/dL) mean
(SD, range):
12.6 (2.0, 1-39)
Urine Pb (ug/L) mean
(SD, range):
10.2 (2.7, 1-239)
Blood Pb (ug/dL) mean
(SD, range)
Pb: 34.6(20.7,2.2-81.6)
Blood Pb (ug/dL) mean
(SD, range):
Pb: 48.5 (17.0, 10.3-99.4
Reference: 9.6 (3.3, 3.8-
20.4)
Significantly higher (p < 0.001) Hct, blood Hgb and RBC count in
blood Pb category 16-39 ug/dL, compared to 1-15 ug/dL
category.
Significant positive correlation between blood Pb concentration
and Hct: V = 42.95, 3 = 0.0586 (r = 0.1553, p < 0.001), blood
Hgb: V= 14.65, 3 = 0.0265 (r = 0.1835, p< 0.001) and RBC
count V = 457, 3 = 0.7120 (r = 0.1408, p < 0.001).
Significantly lower (p < 0.01) blood NADS and ALAD in blood Pb
categories >20 ug/dL compared to <20 ug/dL, with dose trend in
magnitude of difference.
Significant associations between increasing blood Pb and
decreasing blood NADS and ALAD in Pb workers:
NADS: V = 0.843, 3 = -0.00971, r = -0.867, p < 0.001, n = 76
log ALAD: V = 1.8535, 3 = -0.015, r = -0.916, p < 0.001, n = 58
Significant correlation between blood Pb concentration and plasma
and urinary ALA (both log-transformed):
Plasma ALA: V = 0.327, 3 = 0.022, r = 0.742
Urinary ALA: V = -0.387, 3 = 0.022, r = 0.711
Significant correlation between plasma and urinary ALA:
V = 6.038, 3 = 4.962, r= 0.897
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Table 6-9.2 (cont'd). Effects of Lead on Biochemical Effects in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Sugawaraetal. (1991)
Japan
NR
X
to
to
VO
Kim et al. (2002)
Korea
1996
Lee et al. (2000)
Korea
NR
Design: cross-sectional cohort
Subjects: adult Pb workers and reference
group (n = 32, total), ages NR
Outcome measures: plasma and erythrocyte
lipoperoxide and SOD; erythrocyte CAT,
GSH, and methemoglobin
Analysis: comparisons of outcome measures
between Pb workers and reference group,
linear regression and correlation
Design: cross-sectional cohort
Subjects: adult male secondary Pb smelter
workers (n = 83), mean age: 38.7 yr (SD
10.8); reference subjects (n = 24), mean age:
32.0 (SD 10.8)
Outcome measures: blood Hgb, blood ALAD,
blood EP, blood P5N
Analysis: parametric comparison (ANOVA)
of outcome measures between Pb workers and
reference group, correlation, multivariate
linear regression
Design: cross-sectional cohort
Subjects: adult male Pb workers (n = 95;
secondary smelter, PVC-stabilizer
manufacture, battery manufacture); mean age
42.8 yr (SD 9.3, range 19-64); reference group
(n = 13), mean age 35.1 yr (SD 9.9, range
22-54)
Outcome measures: urinary ALA, EP
Analysis: correlation
Blood Pb (ug/dL) mean
(SD, range):
Pb: 57.1(17.6,20-96)
Reference: NR
Blood Pb (ug/dL) mean
(SD)
Pb: 52.4(17.7)
Reference: 6.2(2.8)
Blood Pb (ug/dL) mean
(SD, range):
Pb: 44.6(12.6,21.4-78.4)
Reference: 5.9
(1.2,4.0-7.2)
Significantly (p < 0.01) higher erythrocyte LPO and lower SOD,
CAT and GSH levels in workers compared to reference group.
Erythrocyte lipoperoxide (r = 0.656) and GSH (r = -0.631) were
significantly correlated with blood Pb.
Significantly (p < 0.05) lower blood P5N, ALAD, and Hgb; and
higher blood EP in Pb workers compared to controls.
Significant (p < 0.001) correlations (in Pb worker group) with
blood Pb: P5N (r = -0.704), log EP (r = 0.678), log ALAD
(r = -0.622).
Significant association between increasing EP and decreasing
blood Hgb:
blood Pb 360 ug/dL: 3 =-1.546 (95% CI: -2.387,-0.704),
r2 = 0.513, p = 0.001
blood Pb <60 ug/dL: 3 = -1.036 (95% CI: -1.712,-0.361),
r2 = 0.177, p = 0.003
Significant association between increasing P5N and increasing
blood Hgb (high blood Pb group only):
blood Pb 360 ug/dL: 3 = 0.222 (95% CI: 0.015,0.419),
r2 = 0.513, p = 0.036
Covariates included in model: P5N, log serum ferritin, log EP
Significant correlation between increasing DMSA-provoked
urinary Pb and urinary ALA (r = 0.31, p < 0.002) and EP (r = 0.35,
p< 0.001).
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Table 6-9.2 (cont'd). Effects of Lead on Biochemical Effects in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
X
ON
to
OJ
o
Asia (cont'd)
Schwartz et al. (1997)
Korea
1994-1995
Gurer-Orhan et al.
(2004)
Turkey
NR
Stizenetal. (2003)
Turkey
NR
Design: cross-sectional
Subjects: adult male battery manufacture
workers (n = 57), mean age 32 yrs (SD 6).
Outcome measures: blood Hgb, HgbA1, and
HgbA2, ALAD genotype
Analysis: comparison of outcome measures
between ALAD genotype strata
Design: cross-sectional cohort
Subjects: adult male battery manufacture
workers (n = 20), mean age 35 yr (SD 8);
reference workers (n = 16), mean age
32 yr (SD 9)
Outcome measures: blood ALAD, EP,
erythrocyte MDA, CAT, G6PD, blood
GSH: GSSG
Analysis: comparison of outcome measures
between Pb workers and reference group,
correlation
Design: cross-sectional
Subjects: Male Pb battery manufacture
workers (n = 72), age range 24-45 yrs.
Outcome measures: blood ALAD, urine ALA,
ALAD genotype
Analysis: comparison of outcome measures
between ALAD genotype strata
Blood Pb (ng/dL) mean
(SD):
ALADl,l(n=38): 26.1
(9.8)
ALADl,2(n= 19): 24.0
(11.3)
Blood Pb (ng/dL) mean
(SD):
Pb: 54.6(17)
Reference: 11.8(3.2)
Blood Pb (ng/dL) mean
(SD, range):
All: 34.5(12.8,13.4-71.5
ALADl,l(n=51)
34.4(13.1,13.4-71.8)
ALAD2(n = 21)
34.9(12.6,19.2-69.6)
Mean blood Pb (p = 0.48) and blood Hgb levels (p = 0.34) were
not different between ALAD genotype strata.
Significant correlation between blood Pb concentration and blood
ALAD (r = -0.85, p < 0.0001) and EP (r = 0.83, p < 0.001).
Significant correlation between blood Pb concentration and
erythrocyte MDA (r = 0.80, p = <0.0001), erythrocyte G6PD
(r = 0.70, p < 0.0001, erythrocyte CAT (r = 0.62, p < 0.001), blood
GSH (r = 0.64, p < 0.0005), blood GSSG (r = 0.67, p < 0.0001).
GSH: GSSG ratio lower (p = NR) in Pb workers (3.2), compared
to controls (8.0).
Mean blood Pb concentration (p = 0.88) and blood ALAD activity
(p = 0.33) were not different between ALAD genotype strata.
Mean urinary ALA was significantly higher (p < 0.05) in the
ALAD 1,1 stratum.
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Table AX6-9.3. Effects of Lead on Hematopoietic System in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States
Liebeltetal. (1999)
Connecticut
NR
Design: cross-sectional
Subjects: children (n = 86, 31 female), ages
1-6 yr
Outcome measures: serum EPO, blood Hgb
Analysis: ANOVA of outcome measures
stratified by blood Pb, linear regression
Blood Pb (ng/dL) median
(range):
18(2-84)
84% <35
Significant association between increasing blood Pb concentration
and decreasing serum EPO concentration (3 = -0.03, p = 0.02).
Covariates included in model were blood Hgb (3 = -1.36, p < 0.01)
(age was not included), r2 = 0.224. Predicted decrease in serum EPO
per 10 ng/dL was 0.03 mlU/mL. No significant association between
blood Pb and blood Hgb.
Schwartz etal. (1990)
Idaho
1974
X
ON
to
Design: cross-sectional
Subjects: children (n = 579), ages 1-5 yr,
residing near an active smelter (with
uncontrolled emissions)
Outcome measures: Hct
Analysis: logistic regression
Blood Pb (ng/dL) range:
11-164
Significant association between increasing blood Pb concentration
and probability of anemia (Hct < 35%) (3; = 0.3083 [SE 0.0061])
and age (32 =-0.3831 [SE 0.1134]). A 10% probability of anemia
was predicted to be associated with blood Pb concentration of
-20 ng/dL at age 1 yr, 50 ng/dL at age 3 yr, and 75 ng/dL at age 5
yrs (from Fig. 2 Schwartz et al. (1990).
Regression model relating Hct to blood Pb (BL ng/dL) and age
(AGE, yr): Hct = A/[l + exp(30 + 3jBL + 32AGE)]:
A = 39.42 (SE 0.79), p = 0.0001
30 = -3.112 (SE 0.446), p = 0.0001
3i = 0.0133 (SE 0.0041), p = 0.0005
32 = -0.2016 (SE 0.0905), p = 0.0129
Based on above model, a 10% decrease in hematocrit (from 39.5 to
35.5%) is predicted in association with blood Pb concentrations of
85, 115, and 145 ng/dL, at ages 1, 3, and 5 yrs, respectively.
-------
Table AX6-9.3 (cont'd.). Effects of Lead on Hematopoietic System in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Europe
Graziano et al. (2004)
(Factor Litvak et al.
(1999,1998)
Yugoslavia
1985-1998
Design: prospective
Subjects: children (n = 311; age range
4.5-12 yr) from high-Pb (smelter/refinery)
and low-Pb areas
Outcome measures: blood Hgb, serum EPO.
Analysis: multivariate linear regression
(GEE for repeated measures)
X
ON
to
OJ
to
Blood Pb (ng/dL) range:
4.5 yr: 4.6-73.1
6.Syr: 3.1-71.7
9.0 yr: 2.3-58.1
Blood Pb (ng/dL) means
for ages 4.5-12 yrs:
HighPb: 30.6-39.3
LowPb: 6.1-9.0
Significant association between increasing blood Pb concentration
and increasing serum EPO concentration at ages 4.5 (p < 0.0001)
and 6.5 yr (p < 0.0007), with decreasing regression slope with age:
4.5 yr: 3 = 0.21 (SE 0.043), p = 0.0001; 6.5 yr: 3 = 0.11 (SE 0.41),
p = 0.0103; 9.5 yr: 3 = 0.029 (SE 0.033), p = 0.39; 12 yr: 3 = 0.016
(SE0.031),p = 0.60.
Covariates retained in regression model were age (V), blood Pb (3),
and blood Hgb ((). GEE for repeated measures yielded (Factor-
Litvak et al., 1998, updated from personal communication from
Graziano 07/2005):
(: 0.6097 (95% CI: -0.0915,-0.0479), p < 0.0001
4.5 yr: V = 1.3421 (95% CI: 1.0348, 1.6194), p< 0.0001
3 = 0.2142 (95% CI: 0.1282, 0.3003), p < 0.0001
6.5 yr: V = 1.6620 (95% CI: 1.3737, 1.9503), p< 0.0001
3 = 0.1167 (95% CI: 0.0326, 0.2008), p < 0.001
9.5 yr: V = 1.7639 (95% CI: 1.4586, 2.0691), p< 0.0001
3 = 0.0326 (95% CI: -0.0346, 0.0998), p = 0.1645
12yr: V = 1.8223 (95% CI: 1.524, 2.1121), p< 0.0001
3 = 0.0112 (95% CI: -0.0359, 0.0584), p = 0.1645
Based on the GEE, the predicted increase in serum EPO per 10
|ig/dL increase in blood Pb concentration (at Hgb =13 g/dL) \ was:
1.25 mlU/mL (36%) at age 4.5 yr and 1.18 (18%) at age 6.5 yr.
Blood Hgb levels were not significantly different in children from
high-Pb area (mean 25-38 |ig/dL) compared to low-Pb area (mean
5-9 ng/dL).
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ON
to
Table AX6-9.3 (cont'd). Effects of Lead on Hematopoietic System in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Latin America
Perez-Bravo et al. Design: cross-sectional;
(2004) Subjects: children (n = 93, 43 males), aged
Chile 5-12 yrs who attended school near a
NR powdered Pb storage facility
Outcome measures: blood Hgb and Hct,
ALAD genotype
Analysis: comparison of outcome measures
between ALAD genotype strata
Blood Pb (ng/dL) mean
(SE):
ALADl(n=84): 13.5
(8.7)
ALAD2(n=9): 19.2(9.5)
Mean blood Pb, blood Hgb, and Hct not different between ALAD
genotypes
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Table AX6-9.4. Effects of Lead on Hematopoietic System in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States
Huetal. (1994)
U.S.
1991
Design: survey
Subjects: adult male carpentry workers
(n = 119), mean age: 48.6 yr (range 23-67)
Outcome measures: blood Hct, blood Hgb
Analysis: multivariate linear regression
Blood Pb (ug/dL) mean
(SD, range):
8.3 (4.0, 2-25)
Bone Pb (ug/g) mean
(SD, range)
Tibia: 9.8 (9.5,-15 to 39)
Patella: 13.9 (16.6,-11 to
78)
Significant association between increasing patella bone Pb and
decreasing covariate adjusted blood Hgb (3 = -0.019 [SE 0.0069],
p = 0.008, r2 = 0.078) and blood Hct (3 = -0.052 [SE 0.019],
p = 0.009, r2 = 0.061). After adjustment for bone Pb measurement
error, a 37 ug/dL increase in patella bone Pb level (from the lowest
to highest quintile) was associated with a decrease in blood Hgb and
Hctofllg/L(95%CI: 2.7, 19.3) and 0.03 (95% CI: 0.01,0.05),
respectively.
Covariates considered: age, body mass index, tibia Pb, patella Pb,
blood Pb, current smoking status, alcohol consumption
Covariates retained: patella bone Pb, alcohol consumption, body
mass index.
X
ON
to
Europe
Osterodeetal. (1999)
Austria
NR
Design: cross-sectional cohort
Subjects: adult male Pb workers (n = 20),
ages 46 yr (SD, 7); age-matched reference
group (n = 20)
Outcome measures: blood PCV, blood Hgb,
serum EPO, blood erythroid progenitor
(BFU-E) cell count, blood pluripotent
progenitor (CFU-GEMM) cell count, blood
granulocyte/macrophage progenitor (CFU-
GM) cell count.
Analysis: parametric and nonparametric
comparison of outcomes between Pb workers
and reference group; correlation
Blood Pb (ug/dL) mean
(range):
Pb: 45.5(16-91)
Reference: 4.1 (3-14)
Urine Pb (ug/L) mean
(range):
Pb: 46.6(7-108)
Reference: 3.7(2-16)
Significantly lower (p < 0.001) BFU-E counts in Pb workers who
had blood Pb concentrations 360 ug/dL, compared to reference
group. Significant negative correlation between blood Pb or urine
Pb and CFU-GM and CFU-E. Serum EPO was not correlated with
Hct in Pb workers, however, serum EPO increased exponentially
with decrease in Hct in reference group.
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Table AX6-9.4 (cont'd). Effects of Lead on Hematopoietic System in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
X
ON
to
Europe (cont'd)
Gennartetal. (1992)
Belgium
NR
Mohammed-Brahim
etal. (1985)
Belgium
NR
Hajemetal. (1990)
France
NR
Design: cross-sectional cohort
Subjects: adult battery manufacture workers
(n = 98), mean age, 37.7 yr (range 22-55);
reference group (n = 85), mean age 38.8 yr
(24-55)
Outcome measures: blood Hgb, RBC count,
Hct, blood EP
Analysis: linear regression
Design: cross-sectional cohort
Subjects: adult smelter and ceramics
manufacture workers (n = 38, 13 females);
reference subjects (n = 100) matched with
worker group by age, sex, and
socioeconomic status
Outcome measures: blood P5N, EP, ALAD,
R/ALAD (ratio of ALAD before and after
reactivation).
Analysis: comparison of outcome measures
(ANOVA) between Pb workers and
reference group; correlation
Design: cross-sectional
Subjects: adult males (n = 129), mean age
36 yr (SD 7.8, range 24-55), with no
environmental exposure to Pb
Outcome measures: erythrocyte membrane
activities of Na+-K+-ATPase, Na+-K+-co-
transport, Na+-Li+-antiport, and passive Na+
and K+ permeability
Analysis: linear regression, correlation
Blood Pb (ug/dL) mean
(SD, range):
Pb: 51.0(8.0,40-70)
Reference: 20.9(11.1,4.4-
30.0)
Blood Pb (ug/dL) mean
(SD, range):
Pb: 48.5(9.1,27.8-66.6)
Reference: 14.3 (6.7, 5.6-
33.6)
Urine Pb (ug/g creatinine)
mean (SD, range):
Pb: 84.0(95.9,21.8-587)
Reference: 10.5(8.2, 1.7-
36.9)
Blood Pb (ug/dL)
geometric mean (95% CI,
range):
16.0(15.2-16.8,8.0-33.0)
Hair Pb (ug/g) geometric
mean (95% CI, range):
5.3 (4.44-6.23, 0.9-60)
Significant association between increasing blood Pb concentration
and decreasing blood Hgb (3 = -0.011, r = 0.22, p = 0.003) or Hct
(3 =-0.035, r = 0.24, p< 0.01).
Significant association between increasing blood Pb concentration
and increasing blood EP (3 = 0.0191, r = 0.87, p = 0.0001)
(No apparent analysis of covariables).
Significantly lower (p = NR) P5N in Pb workers (males or females,
or combined) compared to corresponding reference groups.
Correlations with blood Pb:
log P5Nr=-0.79 (p< 0.001)
log ALAD r = -0.97 (p = NR)
R/ALAD r = -0.94 (p < 0.001)
logEPr=0.86(p = NR)
Correlations with urine Pb:
log P5Nr= -0.74 (p = NR)
log ALAD r = -0.79 (p = NR)
R/ALAD r = -0.84 (p < 0.001)
logEPr=0.80(p = NR)
Na+-K+-co-transport activity negatively correlated with blood Pb
concentration (r = -0.23, p = 0.02); linear regression:
V = 583.19, 3 = -170.70
Na+-K+-ATPase activity negatively correlated with hair Pb
(r = -0.18, p = 0.04); simple linear regression:
V = 3.34, 3 = -0.02
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Table AX6-9.4 (cont'd). Effects of Lead on Hematopoietic System in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
X
Oi
to
OJ
Oi
Europe (cont'd)
Poulosetal. (1986)
Greece
NR
Romeo etal. (1996)
Italy
NR
Graziano et al. (1990)
Yugoslavia
1986
Design: cross-sectional cohort
Subjects: adult male cable production
workers who were exposed to Pb (worker 1;
n = 50, mean age 37 yr); male cable workers
who had not direct contact with Pb (worker
2, n = 75, mean age 36.5 yr); reference group
(n = 35, mean age 39 yr)
Outcome measures: blood Hgb, Hct
Analysis: simple linear regression in the
form: mean Hct = a + 3(individual Hct -
group mean Hct)
Design: cross-sectional cohort
Subjects: adult male Pb workers (n = 28),
age range, 17-73; reference group (n = 113),
age range, 21-75 yr
Outcome measures: serum EPO, blood Hgb
Analysis: nonparametric comparison of
outcome measures between Pb workers and
reference group; correlation
Design: prospective
Subjects: pregnant women (n = 1502) from
high-Pb (smelter/refinery) and low-Pb areas
Outcome measures: Hgb
Analysis: comparison of outcome measures
between high-and low-Pb groups
Blood Pb (ng/dL) mean
(SE):
Worker 1: 27.0(0.7)
Worker 2: 18.3(0.6)
Reference: 21.5(1.5)
Blood Pb (ng/dL) mean
(SD, range):
Pbl: 32.3(5.6,30^9)
Pb2: 65.1(16,50-92)
Reference: 10.4(4.3,3-
20)
Blood Pb (ng/dL) mean
(95% CI):
HighPb: 17.1(6.9,42.6)
LowPb: 5.1(2.5,10.6)
Significant association between increasing blood Pb and decreasing
Hct:
Worker 1:
Worker 2:
Reference:
Significant i
blood Hgb:
Worker 1:
Worker 2:
Reference:
V = 46.50, 3 = -0.170 (SE 0.079), p < 0.05
V = 44.57, 3 = -0.180 (SE 0.083), p < 0.05
V = 44.69, 3 = -0.255 (SE 0.044), p < 0.001
t association between increasing blood Pb and decreasing
V = 15.23, 3 = -0.058 (SE 0.028), p < 0.05
V = 14.58, 3 = -0.071 (SE 0.034), p < 0.05
V = 14.64, 3 = -0.087 (SE 0.015), p < 0.001
Significantly (p = 0.021) lower serum EPO in Pb workers compared
to reference group. No significant (p < 0.05) Pb effect on blood
Hgb.
Mean blood Hgb levels (g/dL) in high-Pb group (12.4; 95% CI:
10.3, 14.5) not different from low-Pb group (12.3; 95% CI: 10.0,
14.7).
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Table AX6-9.4 (cont'd). Effects of Lead on Hematopoietic System in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Graziano et al. (1990)
Yugoslavia
1986
Design: prospective
Subjects: pregnant women (n = 48) from
high-Pb (smelter/refinery) and low-Pb areas
(6 highest and lowest mid-pregnancy blood
Pb concentrations), within each of 4 Hgb
strata (g/dL): 9.0-9.9, 10.0-10.9, 11.0-11.9,
12.0-12.9
Outcome measures: Hgb, EPO
Analysis: ANOVA of outcome measures in
subjects stratified by blood Pb and blood
Hgb
Blood Pb (ug/dL) mean
range for Hgb strata
HighPb: 16.9-38.6
LowPb: 2.4-3.6
Significant effect of blood Pb (p = 0.049) and blood Hgb (p = 0.001)
on mid-term and term serum EPO (blood Pb p = 0.055, Hgb
p = 0.009), with significantly lower serum EPO associated with
higher blood Pb.
X
ON
to
Asia
Hsiao etal. (2001)
China
1989-1999
Hsieh et al. (2000)
China
NR
Design: longitudinal
Subjects: adult battery manufacture workers
(n = 30, 13 females), mean age 38.3 yr
Outcome measures: blood Hgb, Hct,
RBC count
Analysis: GEE for repeated measures
(models: linear correlation, threshold
change, synchronous change, lag change);
logistic regression
Design: cross-sectional
Subjects: Adults in general population
(n = 630, 255 females)
Outcome measures: blood Hgb, Hct, RBC
count, ALAD genotype
Analysis: comparison of outcome measures
between ALAD genotype strata
Blood Pb (ug/dL) mean:
1989: 60
1999: 30
Blood Pb ( ug/dL) mean
(SD):
ALADl,l(n=630):
6.5(5.0)
AL ADI,1/2,2 (n= 30):
7.8 (6.0)
Significant association between increasing blood Pb and increasing
RBC count and Hct:
Odds ratios (95% CI):
Synchronous change model:
Blood Hgb: 0.95(0.52,1.78)
RBC count: 3.33(1.78,6.19)
Hct: 2.19(1.31,3.66)
Lag change:
Blood Hgb: 1.70(0.99,2.92)
RBC count: 2.26(1.16,4.41)
Hct: 2.08(1.16,4.41)
Mean blood Pb not different between ALAD genotype strata
(p = 0.17). RBC count, Hgb, Hct not different between ALAD
genotype strata (p = 0.7).
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Table AX6-9.4 (cont'd). Effects of Lead on Hematopoietic System in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Froometal. (1999)
Israel
1980-1993
Solliwayetal. (1996)
Israel
NR
X
ON
to
OJ
oo
Horiguchi et al. (1991)
Japan
NR
Design: longitudinal survey
Subjects: adult male battery manufacturing
workers (n = 94), mean age, 38 yr (SD 9,
range 26-60)
Outcome measures: blood Hgb, blood EP
Analysis: multivariate linear regression
Design: cross-sectional cohort
Subjects: adult male battery manufacture
workers (n = 34), mean age: 44 yr (SD 13);
reference subjects (n = 56), mean age 43 yr
(SD 12); cohorts constructed to have similar
age, ethnic characteristics, socioeconomic
status, education level, and occupation
Outcome measures: blood Hgb, RBC count
Analysis: parametric comparison of
outcome measures between Pb and reference
groups, correlation
Design: cross-sectional cohort
Subjects: adult male secondary Pb refinery
workers (n = 17), mean age: 44.9 yr (range
24-58); reference male subjects (n = 13),
mean age: 33.5 yr (range 22^4)
Outcome measures: RBC deformability
(microfiltration at -20 cm H2O pressure),
RBC count, Hct, blood Hgb
Analysis: comparisons of outcome measures
between Pb workers and reference group
Blood Pb (ug/dL) range of
13-yr individual subject
means: 20-61 ug/dL
Blood Pb (ug/dL) mean
(SD, range):
Pb: 40.7(9.8,23-63)
Reference: 6.7(2.4,1-13)
Blood Pb (ug/dL) mean
(SD):
Pb: 53.5(16.1)
Reference: NR
Urine Pb (ug/L) mean
(SD):
Pb: 141.4(38.1)
Reference: NR
Weak (and probably not significant) covariate-adjusted association
between blood Hgb and individual sample blood Pb (3 = -0.0039
[SE 0.0002]), subject avg blood Pb (3 = -0.0027 [SE 0.0036]) or
blood EP (3 = -0.001 [SE 0.0007]).
Covariates retained in model were age and smoking habits.
Significantly lower (p < 0.05) mean RBC count in Pb workers
compared to reference group. Significant negative correlation
between blood Pb concentration and RBC count (r = -0.29,
p < 0.05). Mean comparison for blood Hgb (p = 0.4); correlation
with blood Pb concentration (r = -0.05, p = 0.7).
Significantly lower RBC deformability (p < 0.01), RBC count
(p < 0.01) Hct (p < 0.01), and blood Hgb (p > 0.001) in Pb workers
compared to reference group.
-------
Table AX6-9.4 (cont'd). Effects of Lead on Hematopoietic System in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Makinoetal. (1997)
Japan
1990-1994
X
ON
to
OJ
VO
Moritaetal. (1997)
Japan
NR
Kim et al. (2002)
Korea
1996
Design: longitudinal survey
Subjects: adult male pigment or vinyl
chloride stabilizer manufacture workers
(n = 1573) mean age 45 yr
Outcome measures: blood Hgb, Hct, RBC
count
Analysis: parametric comparison of
outcome measures, stratified by blood Pb,
linear regression
Design: cross-sectional cohort
Subjects: male Pb workers (n = 76), mean
age 42 yr (range 21-62); reference subjects
(n = 13, 6 females), mean age, males 41 yr
(range 26-52), females 45 yr (range 16-61)
Outcome measures: blood NADS, ALAD
Analysis: comparison of outcome measures
(ANOVA) between blood Pb categories,
linear regression
Design: cross-sectional cohort
Subjects: adult male secondary Pb smelter
workers (n = 83), mean age: 38.7 yr (SD
10.8); reference subjects (n = 24), mean age:
32.0 (SD 10.8)
Outcome measures: blood Hgb, blood
ALAD, blood EP, blood P5N
Analysis: parametric comparison (ANOVA)
of outcome measures between Pb workers
and reference group, correlation, multivariate
linear regression
Blood Pb (ug/dL) mean
(SD, range):
12.6 (2.0, 1-39)
Urine Pb (ug/L) mean (SD,
range):
10.2 (2.7, 1-239)
Blood Pb (ug/dL) mean
(SD, range)
Pb: 34.6(20.7,2.2-81.6)
Blood Pb (ug/dL) mean
(SD)
Pb: 52.4(17.7)
Reference: 6.2(2.8)
Significantly higher (p < 0.001) Hct, blood Hgb, and RBC count in
blood Pb category 16-39 ug/dL, compared to 1-15 ug/dL category.
Significant positive correlation between blood Pb concentration and
Hct: V = 42.95, 3 = 0.0586 (r = 0.1553, p < 0.001), blood Hgb:
V = 14.65, 3 = 0.0265 (r = 0.1835, p < 0.001), and RBC count
V = 457, 3 = 0.7120 (r = 0.1408, p < 0.001).
Significantly lower (p < 0.01) blood NADS and ALAD in blood Pb
categories >20 ug/dL compared to <20 ug/dL, with dose trend in
magnitude of difference.
Significant associations between increasing blood Pb and decreasing
blood NADS and ALAD in Pb workers:
NADS: V = 0.843, 3 = -0.00971, r = -0.867, p < 0.001, n = 76
logALAD: V = 1.8535, 3 = -0.015, r = -0.916, p < 0.001, n = 58
Significantly (p < 0.05) lower blood P5N, ALAD, and Hgb; and
higher blood EP in Pb workers compared to controls.
Significant (p < 0.001) correlations (in Pb worker group) with blood
Pb: P5N (r = -0.704), log EP (r = 0.678), log ALAD
(r = -0.622).
Significant association between increasing EP and decreasing blood
Hgb:
blood Pb 360 ug/dL: 3 = -1.546 (96% CI: -2.387, -0.704),
r2 = 0.513, p = 0.001
blood Pb<60 ug/dL: 3 =-1.036 (96% CI: -1.712,-0.361),
r2 = 0.177, p = 0.003
Significant association between increasing P5N and increasing blood
Hgb (high blood Pb group only):
blood Pb 360 ug/dL: 3 = 0.222 (96% CI: 0.015, 0.419), r2 = 0.513,
p = 0.036
Covariates included in model: P5N, log serum ferritin, log EP
-------
X
to
J^.
o
Table AX6-9.4 (cont'd). Effects of Lead on Hematopoietic System in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Schwartz et al. (1997)
Korea
1994-1995
Design: cross-sectional
Subjects: adult male battery manufacture
workers (n = 57), mean age 32 yrs (SD 6).
Outcome measures: blood Hgb, HgbA1, and
HgbA2, ALAD genotype
Analysis: comparison of outcome measures
between ALAD genotype strata
Blood Pb (ng/dL) mean
(SD):
ALADl,l(n=38): 26.1
(9.8)
ALADl,2(n= 19): 24.0
(11.3)
Mean blood Pb (p = 0.48) and blood Hgb levels (p = 0.34) were not
different between ALAD genotype strata.
-------
Table AX6-9.5. Effects of Lead on the Endocrine System in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States
Mahaffeyetal. (1982)
Wisconsin, New York
NR
Design: cross-sectional
Subjects: children/adolescents (n = 177),
ages l-16yr
Outcome measures: serum 1,25-OH-D
Analysis: comparison of outcome measures
between age, location and blood Pb strata,
linear regression
Blood Pb (ng/dL) range:
12-120
Serum 1,25-OH-D levels were significantly (p = 0.05) higher in the
age group 11-16 yr compared to age groups 1-5 or 6-10 yr.
Increasing blood Pb (log-transformed) significantly associated with
decreasing serum 1,25-OH-D levels in children 1-5 yr of age
(V = 74.5, 3 = -34.5, r = -0.884, n = 50)
Dietary calcium: NR
X
ON
to
Rosen etal. (1980)
New York
NR
Sorrell etal. (1977)
New York
1971-1975
Design: cross-sectional
Subjects: children (n = 45), ages 1-5 yr
Outcome measures: serum calcium, PTH,
25-OH-D, 1,25-OH-D
Analysis: comparison of outcome measures
between blood Pb strata, and before and after
chelation, correlation
Design: cross-sectional
Subjects: children (124), ages 1-6 yr
Outcome measures: serum calcium,
phosphate, 25-OH-D
Analysis: comparison of outcome measures
between blood Pb strata, correlation
Blood Pb (ng/dL) mean
(SE, range):
#29 (n= 15): 18
(1, 10-26)
30-59 (n= 18): 47
(2, 33-55)
360 (n = 12): 74
(98, 62-120)
Blood Pb (ng/dL) mean
(SE):
#29(n = 40): 23(1)
30-59 (n = 35): 48(1)
360(n = 49): 84(5.0)
Significantly higher serum PTH levels and lower 25-OH-D in high-
Pb group compared to low-Pb group; significantly lower 1,25-OH-D
levels in moderate- and high-Pb group compared to low-Pb group.
Serum levels of 1,25-OH-D were negatively correlated with blood
Pb(highPb: r =-0.71, moderate: r=-0.63, p< 0.01). After
chelation therapy, blood Pb decreased and serum 1,25-OH-D levels
increased to levels not significantly different (p > 0.1) from low-Pb
group, 25-OH-D levels were unchanged.
Dietary calcium intake (mg/day) mean (SE):
LowPb: 800(30)
Moderate Pb: 780(25)
HighPb: 580(15)
Serum calcium and 25-OH-D were significantly lower in high Pb
group (p < 0.001). Significant negative correlation between blood
Pb and serum calcium (high Pb, r = -0.78, p < 0.001) or calcium
intake high Pb, (r = -0.82, p < 0.001) in all three Pb strata. Serum
25-OH-D was significantly positively correlated with vitamin D
intake, but not with blood Pb.
Dietary calcium intake (mg/day) mean (SE):
LowPb: 770(20)
Moderate Pb: 760(28)
HighPb: 610(20)
-------
Table AX6-9.5 (cont'd). Effects of Lead on the Endocrine System in Children
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
X
ON
to
J^.
to
United States (cont'd)
Siegeletal. (1989)
Connecticut
1987
Kooetal. (1991)
Ohio
NR
Design: cross-sectional
Subjects: children (n = 68, 32 female), ages
11 mo to 7 yr
Outcome measures: serum FT4, TT4
Analysis: linear regression
Design: longitudinal (subset of prospective)
Subjects: children (n = 105, 56 females), age
21,27, 33 mo
Outcome measures: serum calcium
magnesium, phosphorus, PTH, CAL, 25-OH-
D, 1,25-OH-D, and bone mineral content
Analysis: structural equation modeling
Blood Pb (ng/dL) mean
(range):
25 (2-77)
Blood Pb (ng/dL)
geometric mean
(GSD, range):
Lifetime mean, based on
quarterly measurements:
9.74(1.44,4.8-23.6)
Concurrent:
15.01 (1.52,6-44)
Maximum observed:
18.53(1.53,6-63)
No significant association between blood Pb concentration and
thyroid hormone outcomes. Linear regression parameters:
FT4: V = 1.55 (SE 0.05), 3 = 0.0024 (SE 0.0016), r2 = 0.03,
p = 0.13
TT4: V = 8.960 (SE 0.39), 3 = 0.0210 (SE 0.0127), r2 = 0.04,
p = 0.10
Significant association between increasing blood Pb (In-transformed)
and covariate-adjusted decreasing serum phosphorus
(V = 1.83, 3 = -0.091). No other covariate-adjusted outcomes were
significantly associated with blood Pb.
Covariates retained: age, sex, race, and sampling season.
Dietary calcium intake (mg/day)
#600: n = 4(4%)
600-1200: n=58(55%)
>1200: n = 43(41%)
-------
Table AX6-9.6. Effects of Lead on the Endocrine System in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States
X
ON
to
Cullenetal. (1984)
Connecticut
1979
NR
Robins etal. (1983
Connecticut
NR
Braunstein et al.
(1978)
California
NR
Refowitz (1984)
NR
Design: clinical case study
Subjects: adult males with neurological
symptoms of Pb poisoning
Outcome measures: serum, FSH, LH, PRL,
TES
Analysis: clinical outcomes in terms of
abnormal values
Design: cross-sectional
Subjects: adult male brass foundry workers
(n = 47), age range 20-64 yr
Outcome measures: FT4
Analysis: simple linear regression with
stratification by age and race.
Blood Pb (ng/dL) range:
66-139
Design: clinical
Subjects: adult male secondary Pb smelter
(n = 12), mean age 38 yr, reference group,
(n = 9), mean age 29 yr
Outcome measures: serum EST, FSH, LH,
TES, HCG-stimulated EST and TES, GnRH-
stimulated serum FSH and LH
Analysis: comparisons of outcome measures
between patients symptomatic for Pb
poisoning, Pb-exposed patients not
symptomatic, reference group
Design: cross-sectional survey
Subjects: secondary copper smelter workers
(n=58)
Outcome measures: FT4, TT4
Analysis: linear regression
Blood Pb (ng/dL) range:
16-127
Blood Pb (ng/dL) mean (SD):
Symptomatic (n = 9):
Time of test: 38.7(3.0)
Highest: 88.2(4.0)
Asymptomatic (n = 4):
Time of test: 29.0(5.0)
Highest: 80.0(0.0)
Reference: 16.1(1.7)
Blood Pb (ng/dL) range:
5-60
Five subjects with defects in spermatogenesis (including
azospermia), with no change in basal serum FSH, LH,
PRL, and TES.
Significant association between increasing blood Pb
concentration and decreasing FT4 (V = 1.22,
3 = -0.0042 [95% CI: -0.0002, -0.0082], r2 = 0.085,
p = 0.048). Significant interaction between race (black,
white) and blood Pb.
When stratified by race:
Black: V = 1.13, 3 = -0.0051 (95% CI: 0.0007,
-0.0095), i2 = 0.21, p = 0.03
White: r2 = 0.05, p = 0.27
Strength of association not changed by including age in
the regression model.
Statistically significant (p < 0.05) lower basal serum
TES, higher TES response to HCG, and significantly
reduced LH response to GnRH in workers symptomatic
for Pb poisoning (including EDTA-provoked urinary Pb
>500 ng/24 hr).
No significant association between blood Pb and
hormone levels:
FT4: V = 2.32, 3 = -0.0067 (95% CI: -0.18,0.0043)
TT4: V = NR, 3 =-0.28 (95% CI: -0.059,0.0002)
No significant association when ratified by race (black,
white)
-------
Table AX6-9.6 (cont'd). Effects of Lead on the Endocrine System in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Canada
Alexander et al. (1998,
1996a)
British Columbia
1993
X
ON
to
Schumacher et al.
(1998)
British Columbia
1993
Design: cross-sectional
Subjects: adult male primary smelter workers
(n = 152), mean age 40 yr
Outcome measures: serum FSH, LH, TES
Analysis: multivariate linear regression
Design: cross-sectional
Subjects: adult male smelter workers
(n = 151) mean age 40 yr (SD 7.2)
Outcome measures: serum FT4, TT4, TSH
Analysis: linear regression, ANOVA
Blood Pb (ng/dL) range
(n=81): 22.8(5-58)
Semen Pb (ng/dL) range:
1.9(0.1-17.6)
Blood Pb (ng/dL) mean:
24.1 (n= 151)
<15(n=36)
15-24(n=52)
25-39 (n = 41)
340 (n = 22)
No significant association between covariate-adjusted blood Pb and
hormone levels (p 3 0.5) or prevalence of abnormal levels.
Significant association between covariate-adjusted increasing
semen Pb concentration and decreasing serum TES (3 = -1.57,
p = 0.004).
Covariates considered: age, smoking, alcohol, other metals in blood
(arsenic, cadmium, copper, zinc), abstinence days prior to sample
collection, and sperm count.
No significant effect of blood Pb (categorical) on covariate-adjusted
or unadjusted FT4 (p = 0.68), TT4 (p = 0.13), TSH (p = 0.54). No
significant association of blood Pb with prevalence of abnormal
values of hormones. No significant association between 10-yr avg
blood Pb and hormone levels or prevalence of abnormal values.
Covariates considered: age and alcohol consumption.
Europe
Gennartetal. (1992)
Belgium
NR
Design: cross sectional cohort
Subjects: adult battery manufacture workers
(n = 98), mean age 37.7 yr (SD 8.3, range 22-
55); reference worker group (n = 85), mean
age 38.8 yr (SD 8.7, range 22-55)
Outcome measures: serum TT3, FT4, TT4,
TSH, FSH, LH
Analysis: comparison of outcome measures
between Pb workers and reference group
Blood Pb (ng/dL) mean
(SD, range):
Pb: 51.0(8.0,40.0-75.0)
Reference: 20.9(11.1,4.4-
39.0)
Urine Pb (ng/g creatinine)
mean (range):
Pb: 57.8(1.95,4.3-399)
Reference: 9.75(2.73,
1.45-77.7)
Mean hormone levels in Pb workers and reference group not
different (p = NR); no association between hormone levels and
blood Pb or exposure duration quartile.
-------
Table AX6-9.6 (cont'd). Effects of Lead on the Endocrine System in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
X
ON
to
Europe (cont'd)
Assennato et al. (1987)
Italy
NR
Govonietal. (1987)
Italy
NR
Rodamilans et al.
(1988)
Spain
NR
Design: cross-sectional
Subjects: adult male battery manufacture
workers (n = 39), mean age 41 yr (SD 10);
reference cement plant workers (n = 18), mean
age 40 yr (SD 10)
Outcome measures: serum FSH, LH, PRL,
TES; urinary 17-ketosteroids
Analysis: parametric comparison of outcome
measures between Pb and reference groups
Design: cross-sectional
Subjects: adult male pewter manufacture
workers (n = 78), mean age 35 yr (SD 19,
range 19-52)
Outcome measures: serum PRL
Analysis: parametric comparison of outcome
measures between blood Pb and ZPP strata
Design: cross-sectional cohort
Subjects: adult male Pb smelter workers
(n = 23), age range 21^4 yr; reference group
(n = 20), age range 20-60 yr
Outcome measures: serum FSH, LH, TES,
FTES, SHBG
Analysis: comparison of outcome measures
between exposure duration strata
Blood Pb (ug/dL) mean
(SD):
Pb: 61 (20)
Reference: 18(5)
Urinary Pb (ug/L) mean
(SD):
Pb: 79(37)
Reference: 18(8)
Blood Pb (ug/dL) mean
(SD)/blood ZPP (ug/dL)
mean (SD):
A (n = 22):
28.2(7.1)724.4(8.7)
B(n=33):
60/3(19.3)7131(107)
C(n=13):
33.1(6.7)777.0(42.2)
D (n = 8):
49.1(4.2)734.0(4.8)
Blood Pb (ug/dL) mean
(SD)
Pb5yr(n=10): 76(11)
Reference (n = 20): 17.2
(13)
No significant association (p > 0.05) between blood Pb and
hormone levels.
Significantly (p < 0.02) higher serum PRL in high ZPP strata (B and
C, compared to low ZPP strata A).
Serum TES (p = 0.01) and FTES (p = 0.001) significantly lower and
SHBG significantly higher (p < 0.025) in >5-yr exposure group
compared to reference group; serum LH was significantly (p < 0.01)
higher in all exposure groups compared to reference group.
-------
Table AX6-9.6 (cont'd). Effects of Lead on the Endocrine System in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Erfurthetal. (2001)
Sweden
NR
X
Oi
to
J^.
Oi
Gustafson et al. (1989)
Sweden
NR
Campbell etal. (1985)
UK
NR
Design: cross-sectional cohort
Subjects: adult male active secondary smelter
workers (n = 62), mean age 43 yr (range 21-
78) reference worker group (n = 26), mean
age 43 yr (range 23-66)
Outcome measures: serum FT3, FT4, TSH,
TES, SHBG; TRH-stimulated serum TSH;
GnRH-stimulated serum FSH, LH, and PRL
Analysis: nonparametric comparison of
outcome measures between Pb workers and
reference group; multivariate linear regression
Design: cross-sectional cohort
Subjects: adult male secondary smelter
workers (n = 21) mean age 36.0 yr (SD 10.4);
individually matched for age, sex, and work
shift (n = 21)
Outcome measures: serum FTES, TIES;
FSH, LH, PRL, COR, TSH, TT3, TT4
Analysis: nonparametric comparison of
outcome measures between Pb workers and
reference group, correlation
Design: cross-sectional cohort
Subjects: adult male welders (n = 25);
reference subjects (n = 8) (ages NR)
Outcome measures: plasma ACE, AI, PRA,
plasma ALD
Analysis: linear regression, nonlinear least
squares
Blood Pb (ng/dL) median (range):
Pb: 31.1(8.3-93.2)
Reference: 4.1 (0.8-6.2)
Plasma Pb (ng/dL) median (range):
Pb: 31.1(8.3-93.2)
Reference: 4.1 (0.8-6.2)
Urine Pb (ng/g creatinine) median (range):
Pb: 19.6(3.1-80.6)
Reference: 4.1 (2.4-7.3)
Bone (finger) Pb (ng/g) median (range):
Pb: 25 (-13 to 99)
Reference: 2 (-21 to 14)
Blood Pb (ng/dL) mean (SE):
Pb: 39.4(2.1)
Reference: 5.0(0.2)
Blood Pb(ngML) mean (SD, range): 35.6
(15.3, 8-62)
Basal hormone levels in workers not different from
reference group (p 3 0.05); age-adjusted basal
hormone levels not associated with plasma Pb, blood
Pb, urine Pb, or bone Pb. In an age-matched subset
of the cohorts (n = 9 Pb workers, n = 11 reference),
median GnRH-stimulated serum FSH was
significantly (p = 0.014) lower (77IU/L H hr) in Pb
workers than in reference group (162 IU/L H hr).
No association between stimulated TSH, LH, FSH or
PRL and Pb measures.
Significantly higher TT4 (p < 0.02) and lower serum
FSH (p = 0.009) in Pb workers compared to
reference group. When restricted to the age range
<40 yr, Pb workers had significantly higher TT4
(p = 0.01) and lower FSH (p = 0.03), LH (p = 0.04),
and COR (p = 0.04), compared to the reference
group.
Significant positive correlation between blood Pb
concentration and plasma ALD level (r = 0.53,
p < 0.002), PRA (r = -0.76, p < 0.001), AI (r = 0.68,
p < 0.002), and ACE (r = 0.74, p < 0.001).
-------
Table AX6-9.6 (cont'd). Effects of Lead on the Endocrine System in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Europe (cont'd)
Chalkleyetal. (1998)
UK
1979-1984
X
ON
to
Mason etal. (1990)
UK
NR
McGregor and Mason,
(1990)
UK
NR
Design: cross-sectional
Subjects: adult male primary metal
(cadmium, Pb, zinc) workers (n = 19), ages
NR
Outcome measures: blood calcium, serum 25-
OH-D, 1,25-OH-D,24,25-OH-D
Analysis: comparison of outcome measures
(ANOVA) in group stratified by blood Pb and
urinary cadmium
Design: cross-sectional
Subjects: adult male Pb workers (n = 63), age
range 21-63 yr; reference male subjects
(n = 75), age range 22-64 yr
Outcome measures: serum calcium
phosphate, PTH, 1,25-OH-D
Analysis: comparison of al outcome measures
between Pb workers and reference group,
multivariate regression
Design: cross-sectional cohort
Subjects: adult male Pb workers (n = 90),
mean age (31.5 yr (SD 11.9); reference
workers (n = 86), mean age 40.6 yr (SD 11 .£
Outcome measures: serum FSH, LH, TES,
SHBG
Analysis: comparison of outcome means
between Pb workers and reference groups,
multivariate regression, correlation
Blood Pb (ug/dL) mean
(SD, range): 47(21-76)
Blood Pb (ug/dL) range:
Pb( 15-94)
Reference: NR
Tibia Pb(ng/g)
Pb: 0-93
Reference: NR
Blood Pb (ug/dL) range:
Pb: 17-77
Reference: <12
After stratification by blood Pb and urinary cadmium, serum 1,25-
OH-D levels in strata were significantly different (p = 0.006), with
higher mean values in high blood Pb (>40 ug/dL)/high blood
cadmium (>0.9 ug/L)/high urine cadmium >3.1 ug/L) stratum
compared to low blood Pb (<40 ug/dL)/high blood cadmium
(>0.9 ug/L)/high urine cadmium >3.1 ug/L) stratum. Serum 24,25-
OH-D levels decreased with increasing urinary cadmium (p = NR)
Significantly higher (p < 0.025) prevalence of elevated 1,25-OH-D
(>2 SD of reference mean) in Pb workers (8/63, 13%) compared to
reference group (1/75, 1.3%). Serum levels of 1,25-OH-D
significantly (p < 0.05) higher in Pb workers compared to reference
group.
After stratification of Pb workers into exposure categories (high:
blood Pb 340 ug/dL and bone Pb 340 ug/g, low: blood Pb
#40 ug/dL and bone Pb #40 ug/g), serum 1,25-OH-D levels were
significantly (p < 0.01) higher in the high Pb group.
Increasing blood Pb was significantly (p = NR) associated with
increasing 1,25-OH-D levels (r2 = 0.206; with age and bone Pb
included, r2 = 0.218). After excluding 12 subjects whose blood Pb
concentrations >60 ug/dL, r2 = 0.162 (p = 0.26).
Age-adjusted serum FSH was significantly (p = 0.004) higher in Pb
workers compared to reference group.
Increasing serum FSH significantly (p = NR) associated with blood
Pb and age. Increasing serum LH significantly associated with
increasing exposure duration (not blood Pb or age).
No significant association between serum TES or SHBG and blood
Pb or exposure duration.
No significant difference in prevalence of abnormal hormone levels
between groups.
-------
Table AX6-9.6 (cont'd). Effects of Lead on the Endocrine System in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Latin America
L/.pezetal. (2000)
Argentina
NR
Design: cross sectional
Subjects: adult male battery manufacture
workers (n = 75), age range 21-56 yr;
reference group (n = 62), age NR
Outcome measures: serum TT3, FT4, TT4,
TSH
Analysis: comparison of outcome measures
between Pb workers and reference group,
correlation
Blood Pb (ug/dL) mean
(range):
Pb: 50.9(23.3,8-98)
Reference: 19.1(7.1,4-39)
Significantly higher serum FT4 (p < 0.01) and TT4 (p < 0.05) in Pb
workers compared to reference group. Significant positive
correlation between blood Pb and serum TT3 (p < 0.05), FT4
(p < 0.01), TT4 (p < 0.05), and TSH (p < 0.05), for blood Pb range
8-50 ug/dL; and for TSH (p < 0.05) for blood Pb range 8-
26 ug/dL.
X
ON
to
J^.
oo
Roses etal. (1989)
Brazil
NR
Design: adult male Pb workers (n = 70), age
range 20-53 yr; reference group (n = 58), age
range 25-37 yr.
Outcome measures: serum PRL
Analysis: comparison of outcome measure
between Pb workers and reference group,
linear regression
Blood Pb (ug/dL) range:
Pb: 9-86
Reference: 8-28
Serum RL levels in Pb workers and reference group not
significantly different (p = NR). Correlation between serum PRL
and blood Pb (r = 0.57, p = NR).
Asia
Dursun and Tutus Design: cross-sectional
(1999) Subjects: adult metal powder manufacture
Turkey workers (n = 27) mean age 41.1 yr (SD 5.45,
NR range 25-50); reference group (n = 30), mean
age 42 yr (SD 3.42, range 28^19)
Outcome measures: serum FT4, TT4, FT3,
TT3, TSH
Analysis: parametric comparison of outcome
measures between Pb and reference groups,
simple and multivariate linear regression
Blood Pb (ug/dL) mean
(range):
Pb: 17.1(9.0,6-36)
Reference: 2.4(0.1,1^1)
Significantly (p < 0.0001) higher mean TT4, FT4, and FT3 in Pb
workers compared to reference group.
Significant association between TT4, age (3 = 0.23, p < 0.006), and
exposure duration (3 = -0.20, p > 0.01), but not blood Pb (3 = 0.00,
NR) in linear regression model that included age, blood Pb, and
exposure duration (V = 2.76, r2 = 0.3, p = 0.03).
-------
Table AX6-9.6 (cont'd). Effects of Lead on the Endocrine System in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
Kristal-Boneh et al.
(1998)
Israel
NR
X
ON
to
J^.
VO
Horiguchi et al. (1987)
Japan
NR
Ngetal. (1991)
China
NR
Design: cross-sectional cohort
Subjects: adult male battery
manufacture/recycling workers (n = 56), mean
age 43.4 yr (SD 11.2); reference workers
(n = 90), mean age 41.5 yr (SD 9.3)
Outcome measures: serum calcium,
magnesium, phosphorus, PTH, 25-OH-D,
1,25-OH-D
Analysis: parametric comparison of outcome
measures between Pb workers and reference
group, multivariate linear regression
Design: cross-sectional
Subjects: adult secondary Pb refinery (n = 60,
8 females), mean age 49 yr (range 15-69)
Outcome measures: serum TT3, TT4, TSH
Analysis: comparison of outcome measures
(method NR), between job categories,
correlation
Design: cross-sectional cohort
Subjects: adult male battery manufacture
workers (n = 122), mean age 32.6 (SD 8,2,
range 17-54); reference group (n = 49), mean
age 43.4 yr (SD 13.4, range 18-74)
Outcome measures: serum FSH, LH, PRL,
TES
Analysis: multivariate linear regression
ANCOVA
Blood Pb (ug/dL) mean
(SD, range):
Pb: 42.6(14.5,20-77)
Reference: 4.5(2.6,1.4-
19)
Blood Pb (ug/dL) mean
(SD):
Male: 31.9(20.4)
Female: 13.5(9.5)
Urine Pb (ug/L) mean (SD):
Male: 59.3(76.3)
Female: 26.0(19.7)
Blood Pb (ug/dL) mean
(SD, range):
Pb: 35.2 (13.2, 9.6-77.4)
Reference: 8.3(2.8,2.6-
14.8)
Serum 1,25-OH-D (p = 0.0001) and PTH (p = 0.042) were
significantly higher in Pb workers compared to reference group
Increasing blood Pb concentration (In-transformed) was
significantly associated with covariate-adjusted increasing serum
PTH and 1,25-OH-D levels:
PTH: 3 = 4.8 (95% CI: 0.8, 8.8), r2 = 0.12
1,25-OH-D: 3 = 4.8 (95% CI: 2.7, 6.9), r2 = 0.10
Occupational Pb exposure (yes) significantly associated with
increasing PTH and 1,25-OH-D levels.
Covariates retained: age, alcohol consumption, smoking; calcium,
magnesium, and calorie intake:
PTH: 3 = 7.81 (95% CI: 3.7, 11.5)
1,25-OH-D: 3 = 12.3 (95% CI: 3.84, 20.8)
No significant differences (p = NR) between hormone levels in job
Pb categories: mean blood Pb (ug/dL, SD): 17.9 (10.7), 25.6
(15.4), 49.9 (18.7). No significant correlations (p = NR) between
hormone levels and blood or urine Pb levels.
When cohorts were stratified by age serum FSH and LH were
significantly (p < 0.02) higher in Pb workers <40 yrs of age
compared to corresponding age strata of the reference group; serum
TES was significantly (p < 0.01) lower in Pb workers 340 yr of age.
Covariate-adjusted serum TES were significantly lower (p < 0.01)
in Pb workers in the 310-yr exposure duration category, compared
to the reference group. Covariate-adjusted serum FSH and LH were
significantly higher (p < 0.01) in Pb workers in the <10-yr exposure
duration category, compared to the reference group.
Covariates: age and tobacco smoking.
-------
Table AX6-9.6 (cont'd). Effects of Lead on the Endocrine System in Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
X
ON
to
60 mo.
Africa
Tuppurainen et al.
(1988)
Kenya
1984
Design: cross-sectional
Subjects: adult male battery manufacture
workers (n = 176), mean age 34.1 yr
(SD 8.1, range 21-54)
Outcome measures: serum TT3, FT4,
TT4, TSH
Analysis: multivariate linear regression
and correlation
Blood Pb (ug/dL) mean
(SD, range):
55.9(23.8,14.5-133.6)
Increasing exposure duration significantly associated with
decreasing FT4 (r2 = 0.071, p = 0.001) and TT4 (r2 = 0.059,
p = 0.021); regression not improved by including age or blood Pb.
Strength of association greater when restricted to workers who had
an exposure duration >7.6 yrs: FT4: r2 = 0.33, p< 0.002; TT4:
r2 = 0.21, p< 0.001.
No significant association between blood Pb and hormone levels.
-------
Table AX6-9.7. Effects of Lead on the Hepatic System in Children and Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Children
United States
X
ON
to
Saengeretal. (1984)
New York
NR
Design: clinical cases
Subjects: children (n = 26) ages 2-9 yr; age-
matched reference group (n = NR)
Outcome measures: urinary cortisol and 63-
OH-cortisol (CYP3A metabolite of cortisol)
Analysis: comparison of outcome measure
between children who qualified for EDTA
treatment (EDTA provocation >500 ng/24
hr)
Blood Pb (ng/dL) mean
(SE, range):
Chelated: 46(2,33-60)
Not chelated:
42 (3, 32-60)
Urinary Pb (ng/24 hr) mean
(SE, range), EDTA-
provocation:
Chelated: 991(132,602-
2247)
Not chelated: 298(32,
169^76)
Significantly lower (-45% lower) urinary excretion of 63-OH-
cortisol (p = 0.001) and urinary 63-OH-cortisol: cortisol ratio
(p < 0.001) in children who qualified for chelation than in children
who did not qualify and significantly lower than age-matched
reference group. Urinary 63-OH-cortisol: cortisol ratio was
significantly correlated with blood Pb (r = -0.514, p < 0.001),
urinary Pb, and EDTA provocation urinary Pb (r = -0.593,
p< 0.001).
Adults
Asia
Al-Neamyetal. (2001)
United Arab Emirates
1999
Design: cross-sectional cohort
Subjects: adult male (n = 100) workers (e.g.,
gas pump attendants, garage workers,
printing workers, construction workers),
mean age 34.6 yr (SD 8.0); reference group
(n = 100) matched with Pb workers for age,
sex, nationality.
Outcome measures: serum protein, albumin,
ALT, AP, AST, BUN, (GT, LDH
Analysis: comparison of outcome measures
between Pb workers and reference group
Blood Pb (ng/dL) mean
(SD): Pb: 77.5(42.8)
Reference: 19.8(12.3)
Significantly higher serum AP (p = 0.012) and LDH (p = 0.029) in
Pb workers compared to reference group (values within normal
range).
-------
Reference, Study
Location, and Period
Table AX6-9.7 (cont'd). Effects of Lead on the Hepatic System in Children and Adults
Study Description
Pb Measurement
Findings, Interpretation
Asia (cont'd)
X
ON
to
-------
Table AX6-9.8. Effects of Lead on the Gastrointestinal System
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Canada
Holness and Nethercott
(1988)
Ontario
1982-1984
Design: longitudinal
Subjects: adult male demolition workers
(n= 119), age NR
Outcome measures: prevalence of symptoms
Analysis: comparison of prevalence of
symptoms (questionnaire) stratified by job
phase or blood Pb
Blood Pb (ng/dL) mean
(range):
Phase 1: 59(15-99)
Phase 2: 30
PhaseS: 19
Phase 4: 17
Prevalence of reporting of symptoms of abdominal cramps or
constipation increased with increasing blood Pb concentration
(p<0.05):
<50 ng/dL: 8%, 6%
50-70 ng/dL: 37%, 42%
>70 ng/dL: 77%, 62%
X
ON
to
Caribbean
Matte etal. (1989)
Jamaica
1987
Design: survey
Subjects: battery manufacture/repair
workers (n = 63), mean age -30 yr
(range 11-47)
Outcome measures: prevalence of symptoms
Analysis: comparison of GI symptoms
(questionnaire) between blood Pb strata
Blood Pb (ng/dL)
geometric mean site range:
40-64
Blood Pb distribution:
>60: 60%
<60: 40%
When stratified by blood Pb, <60 ng/dL (low) or 360 ng/dL (high),
prevalence ratio (high/low) was not significant for abdominal pain
(1.5, [95% CI: 0.5, 4.6]), or for any other Pb symptom (e.g. muscle
weakness).
Asia
Bercovitz and Laufer
(1991)
Israel
NR
Design: cross-sectional
Subjects: health individuals (n = 12), peptic
ulcer patients (n = 11), and individuals with
heart disease (n = 11) with environmental
exposure
Analysis: one-way ANOVA used to
compare tooth Pb concentrations in the three
groups
Tooth Pb (:g/g dry dentine)
mean (SE):
Healthy: 25.62(10.15)
Peptic ulcer: 75.02(8.15)
Heart disease: 20.30(2.70)
Tooth Pb levels in patients with gastrointestinal ulcers (n = 11), were
significantly higher than that in healthy subjects (p = 0.001)). Ten of
the 11 peptic ulcer patients had a higher Pb level than the health
subjects. In these 10 patients, increased severity of the ulcer and
longevity of suffering was associated with increased tooth Pb levels.
There was no significant difference between the tooth Pb levels in
the healthy subjects and in the heart disease patients.
-------
Table AX6-9.8 (cont'd). Effects of Lead on the Gastrointestinal System
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
X
ON
to
Asia (cont'd)
Lee et al. (2000)
Korea
NR
Design: cross-sectional cohort
Subjects: adult male Pb workers (n = 95;
secondary smelter, PVC-stabilizer
manufacture, battery manufacture); mean age
42.8 yr (SD 9.3, range 19-64); reference
group (n = 13), mean age 35.1 yr (SD 9.9,
range 22-54)
Outcome measures: prevalence of GI
symptoms (self-administered questionnaire)
Analysis: multivariate logistic regression
Blood Pb (ug/dL) mean
(SD, range):
Pb: 44.6(12.6,21.4-78.4)
Reference:
5.9(1.2,4.0-7.2)
Covariate-adjusted OR for GI symptoms (loss of appetite,
constipation or diarrhea, abdominal pain) in workers (referents not
included in model) were not significant:
Blood Pb (45.7 ug/dL vs. <45.7 ug/dL): OR = 1.8 (95%
CI: 0.7,4.5)
DMSA-provoked urinary Pb (>260.5 vs. <260.5 ug): OR = 1.1
(95% CI: 0.4,2.5)
OR for neuromuscular symptoms were significantly associated with
DMSA-provoked Pb (OR = 7.8 [95% CI: 2.8, 24.5]), but not with
blood Pb.
Covariates retained: age, tobacco smoking, and alcohol
consumption.
Africa
Awad el Karim et al.
(1986)
Sudan
NR
Design: cross-sectional cohort
Subjects: adult male battery manufacture
workers (n = 92), mean age 31.1 yr (SD 8.2);
reference group (n = 40), mean age 33.7 yr
(SD 9.7)
Outcome measures: clinical evaluation
Analysis: comparison of prevalence of
symptoms of Pb poisoning between Pb
workers and reference group
Blood Pb distribution for
Pb workers
>80: 23%
40-80: 72%
<40: 5%
Blood Pb (ug/dL) mean
(SD, range):
Pb: 55-81 (mean range for
various jobs), range 39-107
Reference: 21 (8.5, 7.4-
33.1)
Prevalences of abdominal colic (pain) and constipation were 41.3%
and 41.4 % in Pb workers and 7.5% and 10%, respectively, in the
reference group.
-------
Table AX6-9.9. Effects of Lead on Bone and Teeth in Children and Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Children
United States
Moss etal. (1999)
U.S.
1988-1994
X
ON
to
Design: cross-sectional national survey
(NHANES III)
Subjects: general population (n = 24,901),
ages 2-5 yr (n = 3,547), 6-11 yr (n = 2,894),
312 yr (18,460)
Outcome measures: number of caries (dfs,
DPS, DMFS)
Analysis: multivariate linear regression and
logistic regression
Blood Pb (:g/dL) geometric
mean (SE):
2-5 yr: 2.90(0.12)
6-1 lyr: 2.07(0.08)
312 yr: 2.49(0.06)
Increasing blood Pb concentration (log-transformed) significantly
associated with covariate adjusted increases in dfs:
2-5 yr: 3 = 1.78 (SE 0.59), p = 0.004
6-11 yr: 3 = 1.42 (SE 0.51), p = 0.007
Increases in DFS:
6-11 yr: 3 = 0.48 (SE 0.22), p = 0.03
312 yr: 3 = 2.50 (SE 0.69), p < 0.001
Increases in DMFS:
312 yr: 3 = 5.48 (SE 1.44), p = 0.01
Odds ratio (OR) for caries (31 DMFS, ages 5-17 yr) and population
attributable risk (PAR) in association with 2nd or 3rd blood Pb
tertiles, compared to 1st tertile were:
1st tortile (#1.66 :g/dL)
2nd tertile (1.66-3.52 :g/dL): OR = 1.36 (95% CI: 1.01,2.83);
PAR = 9.6%
3rd tertile (>3.52 :g/dL): OR = 1.66 (95% CI: 1.12, 2.48);
PAR= 13.5%
For an increase of blood Pb of 5 :g/dL, OR = 1.8 (95% CI: 1.3, 2.5)
Covariates retained were age, gender, race/ethnicity, poverty income
ratio, exposure to cigarette smoke, geographic region, educational
level of head of household, carbohydrate and calcium intakes, and
dental visits.
-------
Table AX6-9.9 (cont'd). Effects of Lead on Bone and Teeth in Children and Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
United States (cont'd)
Schwartz etal. (1986)
U.S.
1976-1980
X
Oi
to
-------
Table AX6-9.9 (cont'd). Effects of Lead on Bone and Teeth in Children and Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Adults
United States
X
ON
to
Dye et al. (2002) Design: cross-sectional national survey
U.S. (NHANES III)
1988-1994 Subjects: adults in general population
(n = 10,033; 5,255 females), ages 20-69 yr
Outcome measures: symptoms of
periodontal bone loss (attachment loss,
periodontal pocket depth)
Analysis: multivariate linear regression
Blood Pb (:g/dL) geometric
mean (SE, range):
2.5 (0.08) (2.36% > 10)
Increasing blood Pb (log-transformed) was significantly associated
with increasing prevalence of covariate-adjusted dental furcation
(3 = 0.13 [SE 0.05], p = 0.005). Covariates retained: age, sex,
race/ethnicity, education, smoking, and age of home. Smoking
status interaction was significant when included in the model as an
interaction term (3 = 0.10 [SE 0.05], p = 0.034). When stratified by
smoking status, association between dental furcation and blood Pb
was significant for current smokers (3 = 0.21 [SE 0.07], p = 0.004)
and former smokers (3 = 0.17 [SE 0.07], p = 0.015), but not for
nonsmokers (3 = -0.02 [SE 0.07], p = 0.747).
Europe
Tvinnereim et al.
(2000)
Norway
1990-1994
Design: cross-sectional
Subjects: 1,271 teeth samples collected by
dentists in all 19 counties in Norway
Analysis: Student's t-test comparing metal
concentrations in teeth with caries, roots, and
in different tooth groups
Tooth Pb(:g/g tooth)
geometric mean (SD,
range):
1.16(1.72,0.12-18.76)
Also examined mercury, cadmium, and zinc. All tooth groups had
higher Pb concentrations in carious than in non-carious teeth. The
geometric mean Pb concentration in carious teeth was 1.36 :g/g
compared to 1.10 :g/g (p = 0.001).
-------
Table AX6-9.10. Effects of Lead on Ocular Health in Children and Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
X
ON
to
-------
X
Table AX6-9.10 (cont'd). Effects of Lead on Ocular Health in Children and Adults
Reference, Study
Location, and Period
Study Description
Pb Measurement
Findings, Interpretation
Adults
Europe
Cavalleri et al. (1982)
Italy
NR
Design = cross-sectional cohort
Subjects: adult male vinyl chloride pipe
manufacture workers, exposed to Pb stearate
(n = 35), mean age 45 yr (SD 14, range 21-
59); reference group (n = 35) matched for
age, smoking, and alcohol consumption.
Outcome measures: visual field
Analysis: comparison of outcome measures
between Pb workers and reference group
Blood Pb(:g/dL) mean
(SD, range):
Pb: 46 (14, 21-82)
Reference: 23 (4, 21-37)
Urine Pb (:g/L) mean (SD,
range):
Pb: 71(18,44-118)
Reference: 30(5,21^2)
Visual sensitivity was significantly (p = 0.003) lower in Pb workers
compared to the reference group; however, visual sensitivity index
was not significantly associated with blood or urine Pb. Mesopic
field scotoma prevalence was 10 of 35 (28%) in Pb workers and 0%
in the reference group.
to
-------
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AX6-297
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United States October 2006
EPW600
-------
EPA/600/R-05/144bF
October 2006
Air Quality Criteria for Lead
Volume II
National Center for Environmental Assessment-RTF Division
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, NC
-------
PREFACE
National Ambient Air Quality Standards (NAAQS) are promulgated by the United States
Environmental Protection Agency (EPA) to meet requirements set forth in Sections 108 and 109
of the U.S. Clean Air Act. Those two Clean Air Act sections require the EPA Administrator
(1) to list widespread air pollutants that reasonably may be expected to endanger public health or
welfare; (2) to issue air quality criteria for them that assess the latest available scientific
information on nature and effects of ambient exposure to them; (3) to set "primary" NAAQS to
protect human health with adequate margin of safety and to set "secondary" NAAQS to protect
against welfare effects (e.g., effects on vegetation, ecosystems, visibility, climate, manmade
materials, etc); and (5) to periodically review and revise, as appropriate, the criteria and NAAQS
for a given listed pollutant or class of pollutants.
Lead was first listed in the mid-1970's as a "criteria air pollutant" requiring NAAQS
regulation. The scientific information pertinent to Pb NAAQS development available at the time
was assessed in the EPA document Air Quality Criteria for Lead; published in 1977. Based on
the scientific assessments contained in that 1977 lead air quality criteria document (1977 Lead
AQCD), EPA established a 1.5 |ig/m3 (maximum quarterly calendar average) Pb NAAQS in
1978.
To meet Clean Air Act requirements noted above for periodic review of criteria and
NAAQS, new scientific information published since the 1977 Lead AQCD was later assessed in
a revised Lead AQCD and Addendum published in 1986 and in a Supplement to the 1986
AQCD/Addendum published by EPA in 1990. A 1990 Lead Staff Paper, prepared by EPA's
Office of Air Quality Planning and Standards (OPQPS), drew upon key findings and conclusions
from the 1986 Lead AQCD/Addendum and 1990 Supplement (as well as other OAQPS-
sponsored lead exposure/risk analyses) in posing options for the EPA Administrator to consider
with regard to possible revision of the Pb NAAQS. However, EPA chose not to revise the Pb
NAAQS at that time. Rather, as part of implementing a broad 1991 U.S. EPA Strategy for
Reducing Lead Exposure, the Agency focused primarily on regulatory and remedial clean-up
efforts to reduce Pb exposure from a variety of non-air sources that posed more extensive public
health risks, as well as other actions to reduce air emissions.
-------
The purpose of this revised Lead AQCD is to critically assess the latest scientific
information that has become available since the literature assessed in the 1986 Lead
AQCD/Addendum and 1990 Supplement, with the main focus being on pertinent new
information useful in evaluating health and environmental effects of ambient air lead exposures.
This includes discussion in this document of information regarding: the nature, sources,
distribution, measurement, and concentrations of lead in the environment; multimedia lead
exposure (via air, food, water, etc.) and biokinetic modeling of contributions of such exposures
to concentrations of lead in brain, kidney, and other tissues (e.g., blood and bone concentrations,
as key indices of lead exposure).; characterization of lead health effects and associated exposure-
response relationships; and delineation of environmental (ecological) effects of lead. This final
version of the revised Lead AQCD mainly assesses pertinent literature published or accepted for
publication through December 2005.
The First External Review Draft (dated December 2005) of the revised Lead AQCD
underwent public comment and was reviewed by the Clean Air Scientific Advisory Committee
(CASAC) at a public meeting held in Durham, NC on February 28-March 1, 2006. The public
comments and CASAC recommendations received were taken into account in making
appropriate revisions and incorporating them into a Second External Review Draft (dated May,
2006) which was released for further public comment and CASAC review at a public meeting
held June 28-29, 2006. In addition, still further revised drafts of the Integrative Synthesis
chapter and the Executive Summary were then issued and discussed during an August 15, 2006
CASAC teleconference call. Public comments and CASAC advice received on these latter
materials, as well as Second External Review Draft materials, were taken into account in making
and incorporating further revisions into this final version of this Lead AQCD, which is being
issued to meet an October 1, 2006 court-ordered deadline. Evaluations contained in the present
document provide inputs to an associated Lead Staff Paper prepared by EPA's Office of Air
Quality Planning and Standards (OAQPS), which poses options for consideration by the EPA
Administrator with regard to proposal and, ultimately, promulgation of decisions on potential
retention or revision, as appropriate, of the current Pb NAAQS.
Preparation of this document has been coordinated by staff of EPA's National Center for
Environmental Assessment in Research Triangle Park (NCEA-RTP). NCEA-RTP scientific
staff, together with experts from academia, contributed to writing of document chapters. Earlier
Il-iv
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drafts of document materials were reviewed by scientists from other EPA units and by non-EPA
experts in several public peer consultation workshops held by EPA in July/August 2005.
NCEA acknowledges the valuable contributions provided by authors, contributors, and
reviewers and the diligence of its staff and contractors in the preparation of this document. The
constructive comments provided by public commenters and CASAC that served as valuable
inputs contributing to improved scientific and editorial quality of the document are also
acknowledged by NCEA.
DISCLAIMER
Mention of trade names or commercial products in this document does not constitute
endorsement or recommendation for use.
II-v
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Air Quality Criteria for Lead
(Second External Review Draft)
VOLUME I
EXECUTIVE SUMMARY E-l
1. INTRODUCTION 1-1
2. CHEMISTRY, SOURCES, AND TRANSPORT OF LEAD 2-1
3. ROUTES OF HUMAN EXPOSURE TO LEAD AND OBSERVED
ENVIRONMENTAL CONCENTRATIONS 3-1
4. TOXICOKINETICS, BIOLOGICAL MARKERS, AND MODELS OF LEAD
BURDEN IN HUMANS 4-1
5. TOXICOLOGICAL EFFECTS OF LEAD IN LABORATORY ANIMALS
AND IN VITRO TEST SYSTEMS 5-1
6. EPIDEMIOLOGIC STUDIES OF HUMAN HEALTH EFFECTS
ASSOCIATED WITH LEAD EXPOSURE 6-1
7. ENVIRONMENTAL EFFECTS OF LEAD 7-1
8. INTEGRATIVE SYNTHESIS OF LEAD EXPOSURE/HEALTH
EFFECTS INFORMATION 8-1
VOLUME II
CHAPTER 4 ANNEX (TOXICOKINETICS, BIOLOGICAL MARKERS, AND
MODELS OF LEAD BURDEN IN HUMANS) AX4-1
CHAPTER 5 ANNEX (TOXICOLOGICAL EFFECTS OF LEAD IN
LABORATORY ANIMALS AND IN VITRO TEST SYSTEMS) AX5-1
CHAPTER 6 ANNEX (EPIDEMIOLOGIC STUDIES OF HUMAN HEALTH
EFFECTS ASSOCIATED WITH LEAD EXPOSURE) AX6-1
CHAPTER 7 ANNEX (ENVIRONMENTAL EFFECTS OF LEAD) AX7-1
Il-vi
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Table of Contents
Page
PREFACE iii
DISCLAIMER v
List of Tables xi
List of Figures xiii
Authors, Contributors, and Reviewers xv
U.S. Environmental Protection Agency Project Team for Development
of Air Quality Criteria for Lead xxi
U.S. Environmental Protection Agency Science Advisory Board (SAB)
Staff Office Clean Air Scientific Advisory Committee (CASAC) xxiii
Abbreviations and Acronyms xxv
AX7. CHAPTER 7 ANNEX (ENVIRONMENTAL EFFECTS OF LEAD) AX7-1
AX7.1 TERRESTRIAL ECOSYSTEMS AX7-1
AX7.1.1 Methodologies Used in Terrestrial Ecosystems
Research AX7-1
AX7.1.1.1 Lead Isotopes and Apportionment AX7-1
AX7.1.1.2 Speciation in Assessing Lead
Bioavailability in the Terrestrial
Environment AX7-3
AX7.1.1.3 Tools for Bulk Lead Quantification
and Speciation AX7-9
AX7.1.1.4 Biotic Ligand Model AX7-18
AX7.1.1.5 Soil Amendments AX7-19
AX7.1.2 Distribution of Atmospherically Delivered Lead in
Terrestrial Ecosystems AX7-22
AX7.1.2.1 Speciation of Atmospherically-Delivered
Lead in Terrestrial Ecosystems AX7-24
AX7.1.2.2 Tracing the Fate of Atmospherically-
Delivered Lead in Terrestrial
Ecosystems AX7-31
AX7.1.2.3 Inputs/Outputs of Atmospherically-
Delivered Lead in Terrestrial
Ecosystems AX7-34
AX7.1.2.4 Resistance Mechanisms AX7-44
AX7.1.2.5 Physiological Effects of Lead AX7-46
AX7.1.2.6 Factors that Modify Organism Response AX7-48
AX7.1.2.7 Summary AX7-55
AX7.1.3 Exposure-Response of Terrestrial Species AX7-57
AX7.1.3.1 Summary of Conclusions from the
1986 Lead Criteria Document AX7-59
AX7.1.3.2 Recent Studies on the Effects of Lead
on Primary Producers AX7-61
-------
Table of Contents
(cont'd)
age
AX7.1.3.3 Recent Studies on the Effects of Lead
on Consumers AX7-64
AX7.1.3.4 Recent Studies on the Effects of Lead
on Decomposers AX7-81
AX7.1.3.5 Summary AX7-86
AX7.1.4 Effects of Lead on Natural Terrestrial Ecosystems AX7-88
AX7.1.4.1 Effects of Terrestrial Ecosystem Stresses
on Lead Cycling AX7-89
AX7.1.4.2 Effects of Lead Exposure on Natural
Ecosystem Structure and Function AX7-95
AX7.1.4.3 Effects of Lead on Energy Flows and
Biogeochemical Cycling AX7-99
AX7.1.4.4 Summary AX7-105
AX7.2 AQUATIC ECOSYSTEMS AX7-106
AX7.2.1 Methodologies Used in Aquatic Ecosystem Research AX7-106
AX7.2.1.1 Analytical Methods AX7-107
AX7.2.1.2 Ambient Water Quality Criteria:
Development AX7-108
AX7.2.1.3 Ambient Water Quality Criteria:
Bioavailability Issues AX7-111
AX7.2.1.4 Sediment Quality Criteria:
Development and Bioavailability Issues.... AX7-113
AX7.2.1.5 Metal Mixtures AX7-116
AX7.2.1.6 Background Lead AX7-117
AX7.2.2 Distribution of Lead in Aquatic Ecosystems AX7-117
AX7.2.2.1 Speciation of Lead in Aquatic
Ecosystems AX7-118
AX7.2.2.2 Spatial Distribution of Lead in
Aquatic Ecosystems AX7-122
AX7.2.2.3 Tracing the Fate and Transport of
Lead in Aquatic Ecosystems AX7-142
AX7.2.2.4 Summary AX7-145
AX7.2.3 Aquatic Species Response/Mode of Action AX7-146
AX7.2.3.1 Lead Uptake AX7-146
AX7.2.3.2 Resistance Mechanisms AX7-152
AX7.2.3.3 Physiological Effects of Lead AX7-159
AX7.2.3.4 Factors That Modify Organism
Response to Lead AX7-162
AX7.2.3.5 Factors Associated with Global
Climate Change AX7-174
AX7.2.3.6 Summary AX7-174
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Table of Contents
(cont'd)
age
AX7.2.4 Exposure/Response of Aquatic Species AX7-175
AX7.2.4.1 Summary of Conclusions From the
Previous Criteria Document AX7-175
AX7.2.4.2 Recent Studies on Effects of Lead on
Primary Producers AX7-177
AX7.2.4.3 Recent Studies on Effects of Lead
on Consumers AX7-183
AX7.2.4.4 Recent Studies on Effects of Lead
on Decomposers AX7-193
AX7.2.4.5 Summary AX7-193
AX7.2.5 Effects of Lead on Natural Aquatic Ecosystems AX7-194
AX7.2.5.1 Case Study: Coeur d'Alene River
Watershed AX7-196
AX7.2.5.2 Biotic Condition AX7-198
AX7.2.5.3 Summary AX7-209
REFERENCES AX7-211
Il-ix
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List of Tables
Page
AX7-1.1.1 Relative Standard Deviation (RSD) for Lead Isotope Ratios on
Selected Mass Spectrometers AX7-2
AX7-1.1.2 National Institute of Standards and Technology Lead SRMs AX7-10
AX7-1.1.3 Characteristics for Direct Speciation Techniques AX7-17
AX7-1.2.1 Tissue Lead Levels in Birds Causing Effects AX7-43
AX7-1.3.1 Plant Toxicity Data Used to Develop the Eco-SSL AX7-62
AX7-1.3.2 Plant Toxicity Data Not Used to Develop the Eco-SSL AX7-63
AX7-1.3.3 Avian Toxicity Data Used to Develop the Eco-SSL AX7-66
AX7-1.3.4 Mammalian Toxicity Data Used to Develop the Eco-SSL AX7-72
AX7-1.3.5 Invertebrate Toxicity Data Used to Develop the Eco-SSL AX7-82
AX7-1.3.6 Invertebrate Toxicity Data Not Used to Develop the Eco-SSL AX7-84
AX7-2.1.1 Common Analytical Methods for Measuring Lead in Water,
Sediment, and Tissue AX7-107
AX7-2.1.2 Development of Current Acute Freshwater Criteria for Lead AX7-109
AX7-2.1.3 Recommended Sediment Quality Guidelines for Lead AX7-115
AX7-2.2.1 NAWQA Land Use Categories and Natural/Ambient
Classification AX7-125
AX7-2.2.2 Summary Statistics of Ambient and Natural Levels of Dissolved
Lead in Surface Water AX7-126
AX7-2.2.3 Summary Statistics of Ambient and Natural Levels of Total
Leadin<63 jim Bulk Sediment AX7-127
AX7-2.2.4 Summary Statistics of Ambient and Natural Levels of Lead in
Whole Organism and Liver Tissues AX7-136
AX7-2.2.5 Comparison of NCBP and NAWQA Ambient Lead Levels in
Whole Organism Tissues AX7-138
II-x
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List of Tables
(cont'd)
Page
AX7-2.3.1 Bioconcentration Factors for Aquatic Plants AX7-151
AX7-2.3.2 Bioconcentration Factors for Aquatic Invertebrates AX7-151
AX7-2.4.1 Effects of Lead to Freshwater and Marine Invertebrates AX7-185
AX7-2.4.2 Effects of Pb to Freshwater and Marine Fish AX7-190
AX7-2.4.3 Nonlethal Effects in Amphibians AX7-192
AX7-2.5.1 Ecological Attributed Studies by Maret et al. (2003) in the
Coeur d'Alene Watershed AX7-197
AX7-2.5.2 Essential Ecological Attributes for Natural Aquatic Ecosystems
Affected by Lead AX7-200
Il-xi
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List of Figures
Number Page
AX7-1.1.1 Relationship of bioaccessibility (low, medium, high) versus
speciation as shown with scanning electron micrographs of
various Pb-bearing materials AX7-5
AX7-1.1.2 Variation of bioavailability with particle size AX7-7
AX7-1.1.3 Illustration of particle lability and bioavailability at two different
sites with similar total Pb concentrations and Pb forms AX7-8
AX7-1.1.4 Scanning electron micrograph of a large native Pb particle showing
outer ring of highly bioavailable Pb-chloride and Pb-oxide AX7-8
AX7-1.1.5 Bulk lead versus single species modality AX7-12
AX7-1.2.1 Long-term (1982-1989) annual trends in lead concentrations (|ig/L)
in Lewes, Delaware precipitation AX7-35
AX7-1.3.1 Avian reproduction and growth toxicity data considered in
development of the Eco-SSL AX7-69
AX7-1.3.2 Mammalian reproduction and growth toxicity data considered in
development of the Eco-SSL AX7-81
AX7-2.2.1 Distribution of aqueous lead species as a function of pH based on
a concentration of 1 |igPb/L AX7-119
AX7-2.2.2 Lead speciation versus chloride content AX7-121
AX7-2.2.3 Spatial distribution of natural and ambient surface water/sediment
sites AX7-128
AX7-2.2.4 Spatial distribution of natural and ambient liver tissue sample sites AX7-129
AX7-2.2.5 Spatial distribution of natural and ambient whole organism tissue
sample sites AX7-130
AX7-2.2.6 Frequency distribution of ambient and natural levels of surface
water dissolved lead (|ig/L) AX7-131
AX7-2.2.7 Spatial distribution of dissolved lead in surface water (N = 3445) AX7-132
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List of Figures
(cont'd)
Number Page
AX7-2.2.8 Frequency distribution of ambient and natural levels of bulk
sediment <63 |im total Pb (|ig/g) AX7-134
AX7-2.2.9 Spatial distribution of total lead in bulk sediment <63 um
(N= 1466) AX7-135
AX7-2.2.10 Frequency distribution of ambient and natural levels of lead in
liver tissue (|ig/g dry weight) AX7-137
AX7-2.2.11 Frequency distribution of ambient and natural levels of lead in
whole organism tissue (|ig/g dry weight) AX7-137
AX7-2.2.12 Spatial distribution of lead in liver tissues (N= 559) AX7-139
AX7-2.2.13 Spatial distribution of lead in whole organism tissues (N = 332) AX7-140
AX7-2.2.14 Lead cycle in an aquatic ecosystem AX7-143
-------
Authors, Contributors, and Reviewers
CHAPTER 4 ANNEX (TOXICOKINETICS, BIOLOGICAL MARKERS, AND
MODELS OF LEAD BURDEN IN HUMANS)
Chapter Managers/Editors
Dr. James Brown—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Principal Authors
Dr. Brian Gulson—Graduate School of the Environment, Macquarie University
Sydney, NSW 2109, Australia
Contributors and Reviewers
Dr. Lester D. Grant—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. John Vandenberg—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
CHAPTER 5 ANNEX (TOXICOLOGICAL EFFECTS OF LEAD IN HUMANS
AND LABORATORY ANIMALS)
Chapter Managers/Editors
Dr. Anuradha Mudipalli—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Srikanth Nadadur—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Lori White—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
-------
Authors, Contributors, and Reviewers
(cont'd)
Principal Authors
Dr. Anuradha Mudipalli—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Stephen Lasley—Dept. of Biomedical and Therapeutic Sciences, Univ. of Illinois College of
Medicine, PO Box 1649, Peoria, IL 61656
Dr. Lori White—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Gary Diamond— Syracuse Research Corporation, 8191 Cedar Street, Akron, NY 14001
Dr. N.D. Vaziri—Division of Nephrology and Hypertension, University of California - Irvine
Medical Center, 101, The City Drive, Bldg 53, Room #125. Orange, CA 92868
Dr. John Pierce Wise, Sr.—Maine Center for Toxicology and Environmental Health,
Department of Applied Medical Sciences, 96 Falmouth Street, PO Box 9300, Portland, ME
04104-9300
Dr. Harvey C. Gonick—David Geffen School of Medicine, University of California at
Los Angeles, 201 Tavistock Ave, Los Angeles, CA 90049
Dr. Gene E. Watson—University of Rochester Medical Center, Box 705, Rochester, NY 14642
Dr. Rodney Dietert—Institute for Comparative and Environmental Toxicology, College of
Veterinary Medicine, Cornell University, Ithaca, NY 14853
Contributors and Reviewers
Dr. Lester D. Grant—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Paul Reinhart—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Michael Davis—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. David A. Lawrence—Dept of Environmental and Clinical Immunology, Empire State Plaza
P.O. Box 509, Albany, NY 12201
II-xv
-------
Authors, Contributors, and Reviewers
(cont'd)
Contributors and Reviewers
(cont'd)
Dr. Michael J. McCabe, Jr.—Dept of Environmental Medicine, University of Rochester,
575 Elmwood Avenue, Rochester, NY 14642
Dr. Theodore I. Lidsky—New York State Institute for Basic Research, 1050 Forest RD,
Staten Island, NY 10314
Dr. Mark H. Follansbee—Syracuse Research Corporation, 8191 Cedar St. Akron, NY 14001
Dr. William K. Boyes—National Health and Environmental Effects Research Laboratory,
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Philip J. Bushnell—National Health and Environmental Effects Research Laboratory,
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Ms. Beth Hassett-Sipple—Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Dr. Zachary Pekar—Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Dr. John Vandenberg—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
CHAPTER 6 ANNEX (EPIDEMIOLOGICAL STUDIES OF AMBIENT LEAD
EXPOSURE EFFECTS)
Chapter Managers/Editors
Dr. Jee Young Kim—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Dennis Kotchmar—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. David Svendsgaard—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
-------
Authors, Contributors, and Reviewers
(cont'd)
Principal Authors
Dr. David Bellinger—Children's Hospital, Farley Basement, Box 127, 300 Longwood Avenue,
Boston, MA 02115
Dr. Margit Bleecker—Center for Occupational and Environmental Neurology, 2 Hamill Road,
Suite 225, Baltimore, MD 21210
Dr. Gary Diamond— Syracuse Research Corporation, 8191 Cedar Street.
Akron, NY 14001
Dr. Kim Dietrich—University of Cincinnati College of Medicine, 3223 Eden Avenue,
Kettering Laboratory, Room G31, Cincinnati, OH 45267
Dr. Pam Factor-Litvak—Columbia University Mailman School of Public Health,
722 West 168th Street, Room 1614, New York, NY 10032
Dr. Vic Hasselblad—Duke University Medical Center, Durham, NC 27713
Dr. Stephen J. Rothenberg—CINVESTAV-IPN, Merida, Yucatan, Mexico & National Institute
of Public Health, Cuernavaca, Morelos, Mexico
Dr. Neal Simonsen—Louisiana State University Health Sciences Center, School of Public Health
& Stanley S Scott Cancer Center, 1600 Canal Street, Suite 800, New Orleans, LA 70112
Dr. Kyle Steenland—Rollins School of Public Health, Emory University, 1518 Clifton Road,
Room 268, Atlanta, GA 30322
Dr. Virginia Weaver—Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe
Street, Room 7041, Baltimore, MD 21205
Contributors and Reviewers
Dr. J. Michael Davis—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Lester D. Grant—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Kazuhiko Ito—Nelson Institute of Environmental Medicine, New York University School of
Medicine, Tuxedo, NY 10987
-------
Authors, Contributors, and Reviewers
(cont'd)
Contributors and Reviewers
(cont'd)
Dr. Kathryn Mahaffey—Office of Prevention, Pesticides and Toxic Substances,
U.S. Environmental Protection Agency, Washington, DC 20460
Dr. Karen Martin—Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Dr. Zachary Pekar—Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Ms. Beth Hassett-Sipple—Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Dr. John Vandenberg—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
CHAPTER 7 ANNEX (ENVIRONMENTAL EFFECTS OF LEAD)
Chapter Manager/Editor
Dr. Timothy Lewis—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Principle Authors
Dr. Ruth Hull—Cantox Environmental Inc., 1900 Minnesota Court, Suite 130, Mississauga,
Ontario, L5N 3C9 Canada
Dr. James Kaste—Department of Earth Sciences, Dartmouth College, 352 Main Street,
Hanover, NH 03755
Dr. John Drexler—Department of Geological Sciences, University of Colorado,
1216 Gillespie Drive, Boulder, CO 80305
Dr. Chris Johnson—Department of Civil and Environmental Engineering, Syracuse University,
365 Link Hall, Syracuse, NY 13244
Dr. William Stubblefield—Parametrix, Inc. 33972 Texas St. SW, Albany, OR 97321
-------
Authors, Contributors, and Reviewers
(cont'd)
Principle Authors
(cont'd)
Dr. Dwayne Moore—Cantox Environmental, Inc., 1550ALaperriere Avenue, Suite 103,
Ottawa, Ontario, K1Z 7T2 Canada
Dr. David Mayfield—Parametrix, Inc., 411 108th Ave NE, Suite 1800, Bellevue, WA 98004
Dr. Barbara Southworth—Menzie-Cura & Associates, Inc., 8 Winchester Place, Suite 202,
Winchester, MA 01890
Dr. Katherine Von Stackleberg—Menzie-Cura & Associates, Inc., 8 Winchester Place,
Suite 202, Winchester, MA 01890
Contributors and Reviewers
Dr. Jerome Nriagu—Department of Environmental Health Sciences, 109 South Observatory,
University of Michigan, Ann Arbor, MI 48109
Dr. Judith Weis—Department of Biology, Rutgers University, Newark, NJ 07102
Dr. Sharon Harper—National Exposure Research Laboratory (D205-05), U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Dr. Karen Bradham—National Research Exposure Laboratory (D205-05), U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Dr. Ginger Tennant—Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711
Ms. Gail Lacey—Office of Air Quality Planning and Standards, U.S. Environmental Protection
Agency, Research Triangle Park, NC 27711
Dr. John Vandenberg—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
-------
U.S. Environmental Protection Agency Project Team
for Development of Air Quality Criteria for Lead
Executive Direction
Dr. Lester D. Grant (Director)—National Center for Environmental Assessment-RTF Division,
(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Scientific Staff
Dr. Lori White (Lead Team Leader)—National Center for Environmental Assessment
(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. James S. Brown—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Robert Elias—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (Retired)
Dr. Brooke Hemming—National Center for Environmental Assessment (B243-01), U.S.
Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Jee Young Kim—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Dennis Kotchmar—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Timothy Lewis—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Anuradha Muldipalli—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Srikanth Nadadur—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Paul Reinhart—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. Mary Ross— National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Dr. David Svendsgaard—National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
II-xx
-------
U.S. Environmental Protection Agency Project Team
for Development of Air Quality Criteria for Lead
(cont'd)
Technical Support Staff
Mr. Douglas B. Fennell—Technical Information Specialist, National Center for Environmental
Assessment (B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC
27711 (Retired)
Ms. Emily R. Lee—Management Analyst, National Center for Environmental Assessment
(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Ms. Diane H. Ray—Program Specialist, National Center for Environmental Assessment
(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Ms. Donna Wicker—Administrative Officer, National Center for Environmental Assessment
(B243-01), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (Retired)
Mr. Richard Wilson—Clerk, National Center for Environmental Assessment (B243-01),
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Document Production Staff
Ms. Carolyn T. Perry—Task Order Manager, Computer Sciences Corporation, 2803 Slater Road,
Suite 220, Morrisville, NC 27560
Mr. John A. Bennett—Technical Information Specialist, Library Associates of Maryland,
11820 Parklawn Drive, Suite 400, Rockville, MD 20852
Mr. William Ellis—Records Management Technician, InfoPro, Inc., 8200 Greensboro Drive,
Suite 1450, McLean, VA 22102
Ms. Sandra L. Hughey—Technical Information Specialist, Library Associates of Maryland,
11820 Parklawn Drive, Suite 400, Rockville, MD 20852
Dr. Barbara Liljequist—Technical Editor, Computer Sciences Corporation, 2803 Slater Road,
Suite 220, Morrisville, NC 27560
Ms. Michelle Partridge-Doerr—Publications/Graphics Specialist, TEK Systems, 1201 Edwards
Mill Road, Suite 201, Raleigh, NC 27607
Mr. Carlton Witherspoon—Graphic Artist, Computer Sciences Corporation, 2803 Slater Road,
Suite 220, Morrisville, NC 27560
-------
U.S. Environmental Protection Agency
Science Advisory Board (SAB) Staff Office
Clean Air Scientific Advisory Committee (CASAC)
Chair
Dr. Rogene Henderson*—Scientist Emeritus, Lovelace Respiratory Research Institute,
Albuquerque, NM
Members
Dr. Joshua Cohen—Faculty, Center for the Evaluation of Value and Risk, Institute for Clinical
Research and Health Policy Studies, Tufts New England Medical Center, Boston, MA
Dr. Deborah Cory-Slechta—Director, University of Medicine and Dentistry of New Jersey and
Rutgers State University, Piscataway, NJ
Dr. Ellis Cowling*—University Distinguished Professor-at-Large, North Carolina State
University, Colleges of Natural Resources and Agriculture and Life Sciences, North Carolina
State University, Raleigh, NC
Dr. James D. Crapo [M.D.]*—Professor, Department of Medicine, National Jewish Medical and
Research Center, Denver, CO
Dr. Bruce Fowler—Assistant Director for Science, Division of Toxicology and Environmental
Medicine, Office of the Director, Agency for Toxic Substances and Disease Registry, U.S.
Centers for Disease Control and Prevention (ATSDR/CDC), Chamblee, GA
Dr. Andrew Friedland—Professor and Chair, Environmental Studies Program, Dartmouth
College, Hanover, NH
Dr. Robert Goyer [M.D.]—Emeritus Professor of Pathology, Faculty of Medicine, University of
Western Ontario (Canada), Chapel Hill, NC
Mr. Sean Hays—President, Summit Toxicology, Allenspark, CO
Dr. Bruce Lanphear [M.D.]—Sloan Professor of Children's Environmental Health, and the
Director of the Cincinnati Children's Environmental Health Center at Cincinnati Children's
Hospital Medical Center and the University of Cincinnati, Cincinnati, OH
Dr. Samuel Luoma—Senior Research Hydrologist, U.S. Geological Survey (USGS),
Menlo Park, CA
-------
U.S. Environmental Protection Agency
Science Advisory Board (SAB) Staff Office
Clean Air Scientific Advisory Committee (CASAC)
(cont'd)
Members
(cont'd)
Dr. Frederick J. Miller*—Consultant, Cary, NC
Dr. Paul Mushak—Principal, PB Associates, and Visiting Professor, Albert Einstein College of
Medicine (New York, NY), Durham, NC
Dr. Michael Newman—Professor of Marine Science, School of Marine Sciences, Virginia
Institute of Marine Science, College of William & Mary, Gloucester Point, VA
Mr. Richard L. Poirot*—Environmental Analyst, Air Pollution Control Division, Department of
Environmental Conservation, Vermont Agency of Natural Resources, Waterbury, VT
Dr. Michael Rabinowitz—Geochemist, Marine Biological Laboratory, Woods Hole, MA
Dr. Joel Schwartz—Professor, Environmental Health, Harvard University School of Public
Health, Boston, MA
Dr. Frank Speizer [M.D.]*—Edward Kass Professor of Medicine, Channing Laboratory,
Harvard Medical School, Boston, MA
Dr. Ian von Lindern—Senior Scientist, TerraGraphics Environmental Engineering, Inc.,
Moscow, ID
Dr. Barbara Zielinska*—Research Professor, Division of Atmospheric Science, Desert Research
Institute, Reno, NV
SCIENCE ADVISORY BOARD STAFF
Mr. Fred Butterfield—CASAC Designated Federal Officer, 1200 Pennsylvania Avenue, N.W.,
Washington, DC, 20460, Phone: 202-343-9994, Fax: 202-233-0643 (butterfield.fred@epa.gov)
(Physical/Courier/FedEx Address: Fred A. Butterfield, III, EPA Science Advisory Board Staff
Office (Mail Code 1400F), Woodies Building, 1025 F Street, N.W., Room 3604, Washington,
DC 20004, Telephone: 202-343-9994)
*Members of the statutory Clean Air Scientific Advisory Committee (CASAC) appointed by the
U.S. EPA Administrator
-------
Abbreviations and Acronyms
aFGF
AA
AAL
AAS
ABA
ACBP
ACE
ACh
AChE
ACR
AD
ADC
ADP
AE
AEA
AFC
2-AG
A horizon
AHR
AI
ALA
ALAD
ALAS
ALAU
ALD
ALS
ALT
ALWT
AMEM
AMP
ANCOVA
ANF
Angll
a-fibroblast growth factor
arachidonic acid
active avoidance learning
atomic absorption spectroscopy
p-aminoisobutyric acid
Achenbach Child Behavior Profile
angiotensin converting enzyme
acetylcholine
acetylcholinesterase
acute-chronic ratio
adult
analog digital converter
adenosine diphosphate
anion exchange
TV-arachi dony 1 ethanol amine
antibody forming cells
2-arachidonylglycerol
uppermost layer of soil (litter and humus)
aryl hydrocarbon receptor
angiotensin I
*-aminolevulinic acid
*-aminolevulinic acid dehydratase
aminolevulinic acid synthetase
urinary 5-aminolevulinic acid
aldosterone
amyotrophic lateral sclerosis
alanine aminotransferase
albumin weight
Alpha Minimal Essential Medium
adenosine monophosphate
analysis of covariance
atrial natriuretic factor
angiotensin II
II-xxiv
-------
ANOVA
ANP
AP
AP-1
ApoE
AQCD
Arg
AS52
ASGP-R
AST
ASV
3-AT
ATP
ATP1A2
ATPase
ATSDR
AVCD
AVS
AWQC
3
3FGF
173-HS
33-HSD
173-HSDH
63-OH-cortisol
B
BAEP
BAER
BAF
Bcell
BCFs
BCS
BDNF
BDWT
BEI
analysis of variance
atrial natriuretic peptide
alkaline phosphatase
activated protein-1
apolipoprotein E
Air Quality Criteria Document
arginine
cells derived from the CHO cell line
aceyl glycoprotein receptor
aspartate aminotransferase
anode stripping voltammetry
3-aminotriazole; 3-amino triazide
adenosine triphosphate
sodium-potassium adenosine triphosphase a2
adenosine triphosphatase
Agency for Toxic Substances and Disease Research
atrioventricular conduction deficit
acid volatile sulfide
ambient water quality criteria
beta-coefficient; slope of an equation
3-fibroblast growth factor
173-hydroxysteriod
33-hydroxysteriod dehydrogenase
173-hydroxysteriod dehydrogenase
6-3-hydroxycortisol
both
brainstem auditory-evoked potentials
brainstem auditory-evoked responses
bioaccumulation factor
B lymphocyte
bioconcentration factors
bovine calf serum
brain derived neurotrophic factor
body weight changes
biological exposure index
II-xxv
-------
BFU-E
BLL
BLM
BM
BMI
BDNF
BOTMP
BP
BPb
BSA
BSI
BTQ
BUN
bw, b. wt, BW
C3H10T/12
C3, C4
CA
CAS
45Ca
Ca-ATP
Ca-ATPase
CaCO3
CaEDTA
CAL
CaM
Ca-Mg-ATPase
cAMP
CaNa2 EDTA
CANTAB
CAT
CBCL
CBCL-T
CBL
CBLI
CCB
blood erythroid progenitor
blood lead level
biotic ligand model
basement membrane
body mass index
brain-derived neurotrophic factor
Bruinicks-Oseretsky Test of Motor Proficiency
blood pressure
blood lead concentration
bovine serum albumin
Brief Symptom Inventory
Boston Teacher Questionnaire
blood urea nitrogen
body weight
mouse embryo cell line
complement proteins
chromosome aberration
cornu ammonis 3 region of hippocampus
calcium-45 radionuclide
calcium-dependent adenosine triphosphate
calcium-dependent adenosine triphosphatase
calcium carbonate
calcium disodium ethylenediaminetetraacetic acid
calcitonin
calmodulin
calcium-magnesium-dependent adenosine triphosphatase
cyclic adenosinemonophosphate
calcium disodium ethylenediaminetetraacetic acid
Cambridge Neuropsychological Testing Automated Battery
catalase; Cognitive Abilities Test
Achenbach Child Behavior Checklist
Total Behavior Problem Score
cumulative blood lead
cumulative blood lead index
cytochalasin B
II-xxvi
-------
CCD
CCE
CCL
CCS
Cd
109Cd
CdU
CEC
CESD, CES-D
GFAP
CFU-E
CFU-GEMM
CFU-GM
cGMP
ChAT
CHD
CHO
CI
CLE-SV
CLRTAP
CLS
CMC
CMI
CNS
COH
ConA
COR
CoTx
COX-2
CP
CPT
cr
CRAC
CREB
charge-coupled device
Coordination Center for Effects
carbon tetrachloride
cosmic calf serum
coefficient of component variance of respiratory sinus arrhythmia
cadmium
cadmium-109 radionuclide
urinary cadmium
cation exchange capacity
Center for Epidemiologic Studies Depression (scale)
glial fibrillary acidic protein
colony forming unit blood-erythroid progenitor (cell count)
colony forming unit blood-pluripotent progenitor (cell count)
blood granulocyte/macrophage progenitor (cell count)
cyclic guanosine-3',5'-monophosphate
choline acetyltransferase
coronary heart disease
Chinese hamster ovary cell line
confidence interval
competitive ligand-exchange/stripping voltammetry
Convention on Long-Range Transboundary of Air Pollution
Cincinnati Lead Study
criterion maximum concentration
cell-mediated immunity
central nervous system
cation-osmotic hemolysis
concanavalin A
cortisol
cotreatment
cyclooxygenase-2
coproporphryn
current perception threshold
creatinine
calcium release activated calcium reflux
cyclic AMP-response element binding protein
II-xxvii
-------
CRF
CRI
CSF
CuZn-SOD
CV
CVLT
CVR.R
CYP
CYPSall
D
DA
dbcAMP
DCV
DEAE
DET
DEYO
DPS
dfs
DG
DOT
DL
DMEM
DMEM/F12
DMFS
DMPS
DMSA
DMT
DMTU
DNA
DO
DOC
DOM
DOPAc
DPASV
dp/dt
chronic renal failure
chronic renal insufficiency
cerebrospinal fluid
copper and zinc-dependent superoxide dismutase
conduction velocity
California Verbal Learning Test
coefficient of variation of the R-R interval
cytochrome (e.g., CYP1A, CYP-2A6, CYP3A4, CYP450)
cytochrome P450 Sal 1
D-statistic
dopamine; dopaminergic
dibutyryl cyclic adenosine-3',5'-monophosphate
distribution of conduction velocities
diethylaminoethyl (chromatography)
diffusive equilibrium thin films
death of young
decayed or filled surfaces, permanent teeth
covariate-adjusted number of caries
dentate gyrus
diffusive gradient thin films
DL-statistic
Dulbecco's Minimal Essential Medium
Dulbecco's Minimal Essential Medium/Ham's F12
decayed, missing, or filled surfaces, permanent teeth
2,3-dimercaptopropane 1-sulfonate
2,3-dimercaptosuccinic acid
Donnan membrane technique
dimethylthiourea
deoxyribonucleic acid
distraction osteogenesis
dissolved organic carbon
dissolved organic carbon
3,4-dihydroxyphenylacetic acid
differential pulse anodic stripping voltammetry
rate of left ventricular isovolumetric pressure
-------
DPPD
DR
DSA
DTC
DTK
DTPA
DTT
dw
E
E2
EBE
EBV
EC
ECso
eCB
ECG
Eco-SSL
EDS
EDTA
EEDQ
EEG
EG
EGF
EGG
EGPN
EKG
electro
EM/CM
EMEM
eNOS
EP
EPA
Epi
EPMA
EPO
TV-TV-diphenyl-p-phynylene-diamine
drinking water
delayed spatial alternation
diethyl dithiocarbomate complex
delayed type hypersensitivity
diethylenetriaminepentaacetic acid
dithiothreitol
dry weight
embryonic day
estradiol
early biological effect
Epstein-Barr virus
European Community
effect concentration for 50% of test population
endocannabinoid
el ectrocardi ogram
ecological soil screening level
energy dispersive spectrometers
ethylenediaminetetraacetic acid
7V-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinone
el ectroencephal ogram
egg
epidermal growth factor
effects on eggs
egg production
el ectrocardi ogram
electrophysiological stimulation
experimental medium-to-control medium (ratio)
Eagle's Minimal Essential Medium
endothelial nitric oxide synthase
erythrocyte protoporphyrin
U.S. Environmental Protection Agency
epinephrine
electron probe microanalysis
erythropoietin
II-xxix
-------
EPSC
EPT
ERG
ERL
ERM
EROD
ESCA
ESRD
EST
ESTH
ET
ETOH
EXAFS
EXANES
F
F344
FAV
FBS
FCS
FCV
FD
FEF
FEP
FERT
FEVi
FGF
FI
FIAM
FMLP
fMRI
FR
FSH
FT3
FT4
excitatory postsynaptic currents
macroinvertebrates from the Ephemeroptera (mayflies),
Plecoptera (stoneflies), and Trichoptera (caddisflies) group
electroretinogram; electroretinographic
effects range - low
effects range - median
ethoxyresorufin-0-deethylase
electron spectroscopy for chemical analysis
end-stage renal disease
estradiol
eggshell thinning
endothelein; essential tremor
ethyl alcohol
extended X-ray absorption fine structure
extended X-ray absorption near edge spectroscopy
F-statistic
Fischer 344 (rat)
final acute value
fetal bovine serum
fetal calf serum
final chronic value
food
forced expiratory flow
free erythrocyte protoporphyrin
fertility
forced expiratory volume in one second
fibroblast growth factor (e.g., PFGF, aFGF)
fixed interval (operant conditioning)
free ion activity model
N-f'ormy 1 -L-methi ony 1 -L-l eucy 1 -L-pheny 1 al anine
functional magnetic resonance imaging
fixed-ratio operant conditioning
follicle stimulating hormone
free triiodothyronine
free thyroxine
II-XXX
-------
FTES
FTII
FTPLM
FURA-2
FVC
(-GT
G
GABA
GAG
G12 CHV79
GCI
GD
GDP
GEE
GFAAS
GFR
GGT
GH
GI
GIME-VIP
GIS
GLU
GMAV
GMCV
GMP
GMPH
GnRH
GOT
GP
G6PD, G6PDH
GPEI
gp91phox
GPT
GPx
free testosterone
Fagan Test of Infant Intelligence
flow-through permeation liquid membranes
l-[6-amino-2-(5-carboxy-2-oxazolyl)-5-benzofuranyloxy]-2-(2-
amino-5-methylphenoxy) ethane-7V,7V,jV',jV'-tetraacetic acid
forced vital capacity
(-glutamyl transferase
gestational day
gamma aminobutyric acid
glycosaminoglycan
cells derived from the V79 cell line
General Cognitive Index
gestational day
guanosine diphosphate
generalized estimating equations
graphite furnace atomic absorption spectroscopy
glomerular filtration rate
(-glutamyl transferase
growth hormone
gastrointestinal
gel integrated microelectrodes combined with voltammetric
in situ profiling
geographic information system
glutamate
genus mean acute value
genus mean chronic value
guanosine monophosphate
general morphology
gonadotropin releasing hormone
aspartate aminotransferase
gross productivity
glucose-6-phosphatedehydrogenase
glutathione S-transferase P enhancer element
NAD(P)H oxidase
glutamic-pyruvic transaminase
glutathione peroxidase
II-xxxi
-------
GRO
GRP78
GSD
GSH
GSIM
GSSG
GST
GSTP
GTP
GV
H+
3H
HA
Hb
HBEF
HBSS
HCG; hCG
Hct
HDL
HEP
HET
HFPLM
Hgb
HGF
HH
H-H
HHANES
H-L
HLA
H-MEM
HMP
HNO3
H202
HOME
HOSTE
growth
glucose-regulated protein 78
geometric standard deviation
reduced glutathione
gill surface interaction model
glutathione disulfide
glutathione-^-transferase
placental glutathione transferase
guanosine triphosphate
gavage
acidity
hydrogen-3 radionuclide (tritium)
humic acid; hydroxyapatite
hemoglobin
Hubbard Brook Experimenatl Forest
Hank's Balanced Salt Solution
human chorionic gonadotropin
hematocrit
high-density lipoprotein (cholesterol)
habitat evaluation procedure
Binghamton heterogeneous stock
hollow fiber permeation liquid membranes
hemoglobin
hepatocyte growth factor
hydroxylamine hydrochloride
high-high
Hispanic Health and Nutrition Examination Survey
high-low
human leukocyte antigen
minimum essential medium/nutrient mixture-F12-Ham
hexose monophosphate shunt pathway
nitric acid
hydrogen peroxide
Home Observation for Measurement of Environment
human osteosarcoma cells
II-xxxii
-------
HPLC
H3PO4
HPRT
HR
HSI
H2SO4
HSPG
Ht
HTC
hTERT
HTN
IBL
IBL H WRAT-R
ICD
ICP
ICP-AES
ICP-MS, ICPMS
ID-MS
IFN
Ig
IGF-1
IL
ILL
immuno
IMP
iNOS
i.p., IP
IPSC
IQ
IRT
ISEL
ISI
i.v., IV
IVCD
high-pressure liquid chromatography
phosphoric acid
hypoxanthine phosphoribosyltransferase (gene)
heart rate
habitat suitability indices
sulfuric acid
heparan sulfate proteoglycan
hematocrit
hepatoma cells
catalytic subunit of human telomerase
hypertension
integrated blood lead index
integrated blood lead index H Wide Range Achievement
Test-Revised (interaction)
International Classification of Diseases
inductively coupled plasma
inductively coupled plasma atomic emission spectroscopy
inductively coupled plasma mass spectrometry
isotope dilution mass spectrometry
interferon (e.g., IFN-Q
immunoglobulin (e.g., IgA, IgE, IgG, IgM)
insulin-like growth factor 1
interleukin (e.g., IL-1, IL-13, IL-4, IL-6, IL-12)
incipient lethal level
immunohistochemical staining
inosine monophosphate
inducible nitric oxide synthase
intraperitoneal
inhibitory postsynaptic currents
intelligence quotient
interresponse time
in situ end labeling
interstimulus interval
intravenous
intraventricular conduction deficit
-------
JV
KABC
KTEA
KXRF, K-XRF
LA
LB
LC
LCso
LD50
LDH
LDL
L-dopa
LE
LET
LH
LHRH
LN
L-NAME
LOAEL
LOEC
LOWES S
LPO
LPP
LPS
LT
LT50
LTER
LTP
LVH
liPIXE
liSXRF
MA
MA- 10
MANCOVA
juvenile
Kaufman Assessment Battery for Children
Kaufman Test of Educational Achievement
K-shell X-ray fluorescence
lipoic acid
laying bird
lactation
lethal concentration at which 50% of exposed animals die
lethal concentration at which 74% of exposed animals die
lethal dose at which 50% of exposed animals die
lactate dehydrogenase
low-density lipoprotein (cholesterol)
3,4-dihydroxyphenylalanine (precursor of dopamine)
Long Evans (rat)
linear energy transfer (radiation)
luteinizing hormone
luteinizing hormone releasing hormone
lead nitrate
L-7V°-nitroarginine methyl ester
lowest-observed adverse effect level
lowest-observed-effect concentration
locally weighted scatter plot smoother
lipoperoxide
lipid peroxidation potential
lipopolysaccharide
leukotriene
time to kill 50%
Long-Term Ecological Research (sites)
long term potentiation
left ventricular hypertrophy
microfocused particle induced X-ray emission
microfocused synchrotron-based X-ray fluorescence
mature
mouse Ley dig tumor cell line
multivariate analysis of covariance
II-xxxiv
-------
MAO
MATC
MDA
MDA-TBA
MDCK
MDI
MDRD
MEM
MG
Mg-ATPase
MiADMSA
Mi-DMSA
MK-801
MLR
MMSE
MMTV
MN
MND
MNNG
MPH
MRI
mRNA
MROD
MRS
MS
MSCA
mSQGQs
MT
MVV
MW
N, n
N/A
NAAQS
NAC
NAD
monoamine oxidase
maximum acceptable threshold concentration
malondialdehyde
malondialdehyde-thiobarbituric acid
kidney epithelial cell line
Mental Development Index (score)
Modification of Diet in Renal Disease (study)
Minimal Essential Medium
microglobulin
magnesium-dependent adenosine triphosphatase
monoisamyl dimercaptosuccinic acid
mi monoisoamyl dimercaptosuccinic acid
NMD A receptor antagonist
mixed lymphocyte response
Mini-Mental State Examination
murine mammary tumor virus
micronuclei formation
motor neuron disease
7V-methyl-jV'-nitro-7V-nitrosoguanidine
morphology
magnetic resonance imaging
messenger ribonucleic acid
methoxyresorufm-O-demethylase
magnetic resonance spectroscopy
mass spectrometry
McCarthy Scales of Children's Abiltities
mean sediment quality guideline quotients
metallothionein
maximum voluntary ventilation
molecular weight (e.g., high-MW, low-MW)
number of observations
not available
National Ambient Air Quality Standards
TV-acetyl cysteine
nicotinamide adenine dinucleotide
II-xxxv
-------
NADH
NADP
NAD(P)H, NADPH
NADS
NAF
NAG
Na-K-ATPase
NAWQA
NET
NCBP
NCD
NCS
NCTB
NCV
ND
NDI
NE
NES
NF-KB
NGF
NHANES
NIOSH
NIST
NK
NMDA
NMDAR
NMR
NO
NO2
N03
NOAEC
NOAEL
NOEC
NOEL
NOM
reduced nicotinamide adenine dinucleotide
nicotinamide adenine dinucleotide phosphate
reduced nicotinamide adenine dinucleotide phosphate
nicotinamide adenine dinucleotide synthase
nafenopin
jV-acetyl-3-D-glucosaminidase
sodium-potassium-dependent adenosine triphosphatase
National Water-Quality Assessment
nitro blue tetrazolium
National Contaminant Biomonitoring Program
nuclear chromatin decondensation (rate)
newborn calf serum
Neurobehavioral Core Test Battery
nerve conduction velocity
non-detectable; not detected
nuclear divison index
norepinephrine
Neurobehavioral Evaluation System
nuclear transcription factor-KB
nerve growth factor
National Health and Nutrition Examination Survey
National Institute for Occupational Safety and Health
National Institute for Standards and Technology
natural killer
7V-methyl-D-aspartate
7V-methyl-D-aspartate receptor
nuclear magnetic resonance
nitric oxide
nitrogen dioxide
nitrate
no-observed-adverse-effect concentration
no-observed-adverse-effect level
no-observed-effect concentration
no-observed-effect level
natural organic matter
II-xxxvi
-------
NORs
NOS
NOX
NP
NPSH
NR
NRC
NRK
NS
NSAID
NT
NTA
02
ODVP
OH
7-OH-coumarin
1,25-OH-D, 1,25-OHD3
24,25-OH-D3
25-OH-D3
8-OHdG
O horizon
OR
OSWER
P,P
P300
P450 1A1
P450 1A2
P450CYP3all
PAD
PAH
PAI-1
PAR
Pb
203Pb
204pb 206pb 207pb 208pb
nucleolar organizing regions
nitric oxide synthase; not otherwise specified
nitrogen oxides
net productivity
nonprotein sulfhydryl
not reported
National Research Council
normal rat kidney
nonsignificant
non-steroidal anti-inflammatory agent
neurotrophin
nitrilotriacetic acid
oxygen
offspring development
hydroxyl
7-hydroxy-coumarin
1,25-dihydroxyvitamin D
24,25-dihydroxyvitamin D
25-hydroxyvitamin D
8-hydroxy-2'-deoxyguanosine
forest floor
odds ratio; other oral
Office of Solid Waste and Emergency Response
probability value
event-related potential
cytochrome P450 1A1
cytochrome P450 1A2
cytochrome P450 Sal 1
peripheral arterial disease
polycyclic aromatic hydrocarbon
plasminogen activator inhibitor-1
population attributable risk
lead
lead-203 radionuclide
stable isotopes of lead-204, -206, -207, -208, respectively
II-xxxvii
-------
Pb(Ac)2
PbB
PbCl2
Pb(ClO4)2
PBG-S
PBMC
Pb(N03)2
PbO
PBP
PbS
PbU
PC12
PCR
PCV
PDE
PDGF
PDI
PEC
PEF
PG
PHA
Pi
PIXE
PKC
plNEpi
PMA
PMN
PMR
PN
P5N
PND
p.o.,PO
POMS
lead-210 radionuclide
lead acetate
blood lead concentration
lead chloride
lead chlorate
porphobilinogen synthase
peripheral blood mononuclear cells
lead nitrate
lead oxides (or litharge)
progressive bulbar paresis
galena
urinary lead
pheochromocytoma cell
polymerase chain reaction
packed cell volume
phosphodiesterase
platelet-derived growth factor
Psychomotor Development Index
probable effect concentration
expiratory peak flow
prostaglandin (e.g., PGE2, PGF2); prostate gland
phytohemagglutinin A
inorganic phosphate
particle induced X-ray emission
protein kinase C
plasma norepinephrine
progressive muscular atrophy
polymorphonuclear leucocyte
proportionate mortality ratio
postnatal (day)
pyrimidine 5'-nucleotidase
postnatal day
per os (oral administration)
Profile of Mood States
parts per billion
II-xxxviii
-------
ppm
PPVT-R
PRA
PRL
PROG
PRR
PRWT
PST
PTH
PTHrP
PVC
PWM
PRWT
QA/QC
Q/V
r
R2
r2
226Ra
R/ALAD
RAVLT
86Rb
RBA
RBC
RBF
RBP
RBPH
RCPM
REL
REP
RHIS
222Rn
RNA
ROS
ROS 17.2.8
parts per million
Peabody Picture Vocabulary Test-Revised
plasma renin activity
prolactin
progeny counts or numbers
prevalence rate ratio
progeny weight
percent transferrin saturation
parathyroid hormone
parathyroid hormone-related protein
polyvinyl chloride
pokeweed mitogen
progeny weight
quality assurance/quality control
flux of air (Q) divided by volume of culture (V)
Pearson correlation coefficient
multiple correlation coefficient
correlation coefficient
most stable isotope of radium
ratio of ALAD activity before and after reactivation
Rey Auditory Verbal Learning Test
rubidium-86 radionuclide
relative bioavailablity
red blood cell; erythrocyte
renal blood flow
retinol binding protein
reproductive behavior
Ravens Colored Progressive Matrices
rat epithelial (cells)
reproduction
reproductive organ histology
most stable isotope of radon
ribonucleic acid
reactive oxygen species
rat osteosarcoma cell line
II-xxxix
-------
RPMI 1640 Roswell Park Memorial Institute basic cell culture medium
RR relative risk; rate ratio
RT reaction time
RSEM resorbed embryos
RSUC reproductive success (general)
RT reproductive tissue
ZSEM sum of the molar concentrations of simultaneously extracted metal
SA7 simian adenovirus
SAB Science Advisory Board
SAM ^-adenosyl-L-methionine
SBIS-4 Stanford-Binet Intelligence Scale-4th edition
s.c., SC subcutaneous
SCAN Test for Auditory Processing Disorders
SCE selective chemical extraction; sister chromatid exchange
SCP stripping chronopotentiometry
SD Spraque-Dawley (rat); standard deviation
SDH succinic acid dehydrogenase
SDS sodium dodecyl sulfate; Symbol Digit Substitution
SE standard error; standard estimation
SEM standard error of the mean
SES socioeconomic status
sGC soluble guanylate cyclase
SH sulfhydryl
SHBG sex hormone binding globulin
SHE Syrian hamster embryo cell line
SIMS secondary ion mass spectrometry
SIR standardized incidence ratio
SLP synthetic leaching procedure
SM sexually mature
SMAV species mean acute value
SMR standardized mortality ratio
SNAP Schneider Neonatal Assessment for Primates
SNP sodium nitroprusside
SO2 sulfur dioxide
SOD superoxide dismutase
II-xl
-------
SOPR
SPCL
SPCV
SQGs
SRA
SRD
SRIF
SRM
SRT
SSADMF
SSB
SSEP
StAR
STORE!
SVC
SVRT
T
TA
TABL
T&E
TAT
TB
TEARS
TBPS
TCDD
Tcell
TCLP
TE
TEC
TEDG
TEL
TES
TEWT
TF
TG
sperm-oocyte penetration rate
sperm cell counts
sperm cell viability
sediment quality guidelines
Self Reported Antisocial Behavior scale
Self Report of Delinquent Behavior
somatostatin
Standard Reference Material
simple reaction time
Social Security Administration Death Master File
single-strand breaks
somatosensory-evoked potential
steroidogenic acute regulatory protein
STOrage and RETrieval
sensory conduction velocity
simple visual reaction time
testosterone
tail
time-averaged blood lead
threatened and endangered (species)
tyrosine aminotransferase
tibia
thiobarbituric acid-reactive species
Total Behavior Problem Score
methionine-choline-deficient diet
T lymphocyte
toxic characteristic leaching procedure
testes
threshold effect concentration
testes degeneration
tetraethyl lead
testosterone
testes weight
transferrin, translocation factor
6-thioguanine
-------
TGF
TH
232^
TLC
TNF
TOP
tPA
TPRD
TRH
TRY
TSH
TSP
TT3
TT4
TIES
TTR
TU
TWA
TX
U
235U, 238U
UCP
UDP
UNECE
Ur
USFWS
USGS
UV
V79
VA
vc
VDR
VE
VEP
VI
transforming growth factor
tyrosine hydroxylase
stable isotope of thorium-232
Treatment of Lead-exposed Children (study)
tumor necrosis factor (e.g., TNF-a)
time-of-flight
plasminogen activator
total production
thyroid releasing hormone
toxicity reference value
thyroid stimulating hormone
triple-super phosphate
total triiodothyronine
serum total thyroxine
total testosterone
transthyretin
toxic unit
time-weighted average
tromboxane (e.g., TXB2)
uriniary
uranium-234 and -238 radionuclides
urinary coproporphyrin
uridine diphosphate
United Nations Economic Commission for Europe
urinary
U.S. Fish and Wildlife Service
United States Geological Survey
ultraviolet
Chinese hamster lung cell line
Veterans Administration
vital capacity; vitamin C
vitamin D receptor
vitamin E
visual-evoked potential
variable-interval
-------
vitC
vitE
VMA
VMI
VSM
VSMC
WAIS
WDS
WHO
wise
WISC-R
WO
WRAT-R
WT
WTHBF-6
ww
XAFS
XANES
XAS
XPS
X-rays
XRD
XRF
ZAP
ZnNa2 DTPA
ZnNa2 EDTA
ZPP
vitamin C
vitamin E
vanilmandelic acid
Visual-Motor Integration
vascular smooth muscle (cells)
vascular smooth muscle cells
Wechsler Adult Intelligence Scale
wavelength dispersive spectrometers
World Health Organization
Wechsler Intelligence Scale for Children
Wechsler Intelligence Scale for Children-Revised
whole organism
Wide Range Achievement Test-Revised
wild type
human liver cell line
wet weight
X-ray absorption fine structure
X-ray absorption near edge spectroscopy
X-ray absorption spectroscopy
X-ray photoelectron spectroscopy
synchrotron radiation
X-ray diffraction
X-ray fluorescence
correction in reference to three components of matrix effects:
atomic number (Z), absorption (A), and fluorescence (F)
zinc disodium diethylenetriaminepentaacetic acid
zinc disodium ethylenediaminetetraacetic acid
zinc protoporphyrin
-------
AX7. CHAPTER 7 ANNEX - ENVIRONMENTAL
EFFECTS OF LEAD
AX7.1 TERRESTRIAL ECOSYSTEMS
AX7.1.1 Methodologies Used in Terrestrial Ecosystems Research
The distribution of Pb throughout the terrestrial ecosystem, via aerial deposition, has been
discussed throughout this document. Its further impacts on soil, sediment, and water provide
numerous pathways that may promote unacceptable risk to all levels of biota. Stable isotopes of
Pb have been found useful in identifying sources and apportionment to various sources. One of
the key factors affecting assessment of risk is an understanding, and perhaps quantification, of
bioavailability. Therefore, the bioavailability of Pb is a key issue to the development of
NAAQS. However, the discussion of all methods used in characterizing bioavailability is
beyond the scope of this chapter. The following topics are discussed in this chapter.
• Lead Isotopes and Apportionment
• Methodologies to determine Pb speciation
• Lead and the Biotic Ligand Model (BLM)
• In situ methods to reduce Pb bioavailability
AX7.1.1.1 Lead Isotopes and Apportionment
Determination of the extent of Pb contamination from an individual source(s) and its
impact are of primary importance in risk assessment. The identification of exposure pathway(s)
is fundamental to the risk analysis and critical in the planning of remediation scenarios.
Although societies have been consuming Pb for nearly 9,000 years, production of Pb in
the United States peaked in 1910 and 1972, at approximately 750 and 620 kt/year, respectively
(Rabinowitz, 2005). The diversity of potential Pb sources (fossil fuel burning, paint pigments,
gasoline additives, solders, ceramics, batteries) and associated production facilities (mining,
milling, smelting-refining) make fingerprinting of sources difficult. (See Chapter 2 and its
Annex for additional information on sources.) Therefore, dealing with multiple sources (point
and nonpoint), a reliable and specific fingerprinting technique is required. It has been well
established (Sturges and Barrie, 1987; Rabinowitz, 1995) that the stable isotope composition of
AX7-1
-------
Pb is ideally suited for this task. Lead isotopic ratio differences often allow multiple sources to
be distinguished, with an apportionment of the bulk Pb concentration made to those sources.
Lead has four stable isotopes: 204Pb, 206Pb, 207Pb, and 208Pb in natural abundances of 1.4,
24.1, 22.1, and 52.4%, respectively. The radiogenic 206Pb, 207Pb, and 208Pb are produced by
radioactive decay of 238U, 235U, and 232Th, respectively. Thus, the isotopic composition of Pb
varies based on the U:Pb and Th:Pb ratios of the original ore's source and age (Faure, 1977).
Because of the small fractional mass differences of the Pb isotopes, ordinary chemical and
pyrometallurgical reactions will not alter their original composition. Therefore, anthropogenic
sources reflect the isotopic composition of the ores from which the Pb originated.
To acquire the Pb isotopes, a sample, generally in aqueous form, is analyzed on an
ICP/MS (quadrapole, magnetic sector, or time-of-flight). Studies reviewing the most common
analytical and sample preparation procedures include Ghazi and Millette (2004), Townsend et al.
(1998), and Encinar et al. (2001a,b). The correction factor for mass discrimination biases is
generally made by analyzing the National Institute for Standards and Technology (NIST),
Standard Reference Material (SRM) 981 and/or spiked 203T1 and 205T1 isotopes (Ketterer et al.,
1991; Begley and Sharp, 1997). The overall success of Pb isotope fingerprinting is generally
dependent on analysis precision, which in turn depends on the type of mass analyzer used
(Table AX7-1.1.1).
Table AX7-1.1.1. Relative Standard Deviation (RSD) for Lead Isotope
Ratios on Selected Mass Spectrometers
RSD
204pb.206pb
207pb.206pb
208pb:206pb
Quadrapole
0.0031
0.0032
0.0026
Double-Focusing
0.0032
0.0027
0.0024
Single-Focusing
Magnetic Sector
0.00053
0.00053
0.00053
High-Resolution
Magnetic Sector
ICP/MS
0.0011
0.00048
0.00046
An extensive database comprising primarily North American Pb sources can be assembled
from Doe and Rohrbough (1977), Doe and Stacey (1974), Doe et al. (1968), Heyl et al. (1974),
AX7-2
-------
Leach et al. (1998), Stacey et al. (1968), Zartman (1974), Cannon and Pierce (1963), Graney
et al. (1996), Unruh et al. (2000), James and Henry (1993), Rabinowitz (2005), and
Small (1973).
The use of Pb isotopes to quantitatively apportion source contributions follows the simple
mixing rule when only two sources are possible (Faure, 1977). Once multiple sources need to be
considered, a unique solution can no longer be calculated (Fry and Sherr, 1984). Phillips and
Gregg (2003) have designed a model to give feasible source contributions when multiple sources
are likely. Many studies have demonstrated the usefulness of this apportionment technique.
Media of all types have been studied: water (Flegal et al., 1989a,b; Erel et al., 1991; Monna
et al., 1995), ice (Planchon et al., 2002), dust (Adgate et al., 1998; Sturges et al., 1993), and
soil/sediments (Hamelin et al., 1990; Farmer et al., 1996; Bindler et al., 1999; Haack et al., 2004;
Rabinowitz and Wetherill, 1972; Rabinowitz, 2005; Ketterer et al., 2001).
AX7.1.1.2 Speciation in Assessing Lead Unavailability in the Terrestrial Environment
One of the three processes defined by the National Research Council in its review on
bioavailability (NRC, 2002) is "contaminant interactions between phases", more commonly
referred to as "speciation."
A wide variety of analytical (XRD, EPMA, EXAFS, PIXE, XPS, XAS, SIMS) and
chemical speciation modeling (SOILCHEM, MINTEQL, REDEQL2, ECOSAT, MINTEQA2,
HYDRAQL, PHREEQE, WATEQ4F) tools have been used to characterize a metal's speciation
as it is found in various media. Currently, for risk assessment purposes (not considering
phytotoxicity), where large sites with numerous media, pathways, and metals must often be
characterized in a reasonable time frame, electron microprobe analysis (EMPA) techniques
provide the greatest information on metal speciation. Other techniques such as extended X-ray
absorption fine structure (EXAFS) and extended X-ray absorption near edge spectroscopy
(EXANES) show great promise and will be important in solving key mechanistic questions.
In the case of phytotoxicity, the speciation of metals by direct measurement or chemical models
of pore-water chemistry is most valuable. Further work needs to be done in developing
analytical tools for the speciation of the methyl-forming metals (Hg, As, Sb, Se, and Sn) in soils
and sediments.
AX7-3
-------
Concept
For a given metal or metalloid (hereafter referred to as metal), the term speciation refers
to its chemical form or species, including its physicochemical characteristics that are relevant to
bioavailability. As a result of the direct impact these factors often have on a metal's
bioavailability, the term "bioaccessibility" has been adopted to define those factors.
Speciation Role
The accumulation of metals in the lithosphere is of great concern. Unlike organic
compounds, metals do not degrade and, thus, have a greater tendency to bioaccumulate. It is
now well accepted that knowledge of the bulk, toxic characteristic leaching procedure (TCLP),
or synthetic leaching procedure (SLP) concentrations for any metal is not a controlling factor in
understanding a metal's environmental behavior or in developing remedies for its safe
management. Although these tests are essential to site characterization and management, they
offer no insight into risk assessment. Rather, it is the metal's bioavailability (the proportion of a
toxin that passes a physiological membrane [the plasma membrane in plants or the gut wall in
animals] and reaches a target receptor [cytosol or blood]), which plays a significant role in the
risk assessment of contaminated media.
The NRC review (NRC, 2002) on bioavailability defined bioavailability processes in
terms of three key processes:
• contaminant interactions between phases (association-dissociation/bound-released),
• transport of contaminants to organism, and
• passage across a physiological membrane.
As mentioned previously, the first process is more commonly referred to as speciation.
The speciation of a toxic metal in the environment is a critical component of any ecosystem
health risk assessment. Four important toxicologic and toxicokinetic determinants relating
speciation to bioavailability are the (1) chemical form or species, (2) particle size of the metal
form, (3) lability of the chemical form, and (4) source.
AX7-4
-------
Chemical Form of Species
The solid phase in a medium controls the activity of a metal in solution, whether the
solution is surface, ground, or pore water or GI fluids, and plays a profound role in metal
bioavailability. This is perhaps best illustrated by in vivo and in vitro results for many of the
common Pb-bearing minerals (Drexler, 1997) (Figure AX7-1.1.1). The metal species found in
media are often diverse, and data suggest that their bioavailability may be significantly
influenced by site-specific variations within these identified metal species (Davis et al., 1993;
Ruby et al., 1992; Drexler and Mushak, 1995).
LOW (1-20)
PbS
Slag
Pb-FeOOH
Native Pb
% ,
-------
(1979) observed that "the smaller the lead particle, the higher blood lead level." Similar
observations were made by Healy et al. (1992) using and an in vitro dissolution technique.
Drexler (1997) presented in vitro results on numerous Pb-bearing phases ranging in particle size
from 35 to 250 jim. While all phases studied showed increased bioavailability with decreasing
particle size, more significantly, not all forms showed the same degree or magnitude of change
(Figure AX7-1.1.2). Atmospheric particles are generally found to occur in bimodal populations:
fine; 0.1 to 2.5 |im and coarse; 2.5 to 15 jim. This distribution is both a function of there
transport mechanism and emission source. Although the upper size limit for particles that can be
suspended in air is about 75 jim (Cowherd et al., 1974), other means of mechanical entrainment
(saltation, and creep) can transport particles as large as 1000 jim, supporting the importance of
fugative emissions on media contamination. In addition, particle size can change post
depositional, as soluble forms re-precipitate or sorb onto other surfaces. Limited data are
available on the particle-size of discrete Pb phases from multimedia environments. One example
is the study by Drexler, 2004 at Herculaneum, Missouri. At this site, galena (PbS) was the
dominant Pb species with mean particle-size distributions of 4, 6, and 14 jim in PMi0 filters,
house dust, and soils, respectively. These findings support the conclusion that aerial transport
was the primary mechanism for Pb deposition in residential yards. Finally, such laboratory data
have been supported by extensive epidemiologic evidence, enforcing the importance of particle
size (Bornschein et al., 1987; Brunekreef et al., 1983; Angle et al., 1984).
Particle Lability
The impact on bioavailability of a metal particle's lability (its associations within the
medium matrix) is not well documented, but it follows the premise put forth by many of the
developing treatment technologies regarding its being bound or isolated from its environment.
Data from several EPA Superfund sites and the Region VIII swine study (U.S. Environmental
Protection Agency, 2004a) suggest that matrix associations, such as liberated versus enclosed,
can play an important part in bioavailability. As illustrated in Figure AX7-1.1.3, two different
media with similar total Pb concentrations and Pb forms (slag, Pb-oxide, and Pb-arsenate)
exhibit significantly different bioavailabilities. In the Murray, UT sample (bioaccumulation
factor [BAF] = 53%), a greater fraction of the more bioavailable Pb-oxides are liberated and
not enclosed in the less-soluble glass-like slag as observed in the Leadville, CO sample
AX7-6
-------
Anglesite
20 40
Minutes
60
38|_im
b.
150r
Slag
c.
100r
PbO
Figure AX7-1.1.2. Variation of bioavailability with particle size.
(BAF = 17%). Other evidence is more empirical, as illustrated in Figure AX7-1.1.4, where a
large particle of native Pb is shown to have developed a weathering ring of highly bioavailable
Pb-chloride and Pb-oxide. Such observations can be useful in understanding the mechanistic
phenomena controlling bioavailability. In addition, they will aid in developing and validating
models to predict metal-environment interactions.
AX7-7
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Murry
BAF 53%
11500mg/kg Pb
20% liberated
Leadville AV
BAF 17%
10600 mg/kg Pb
5% liberated
Figure AX7-1.1.3. Illustration of particle lability and bioavailability at two different sites
with similar total Pb concentrations and Pb forms.
500[jm
BEI Baseline
Figure AX7-1.1.4. Scanning electron micrograph of a large native Pb particle showing
outer ring of highly bioavailable Pb-chloride and Pb-oxide.
AX7-8
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Source
Although the source of a metal is not directly related to bioavailability, it plays an
important role in risk assessment with the evaluation of metal (1) pathways, (2) background,
and (3) apportionment. It is important to understand a metal's pathway before any remedial
action can be taken; otherwise, recontamination of the primary pathway and reexposure can
occur. Knowledge of background is important, as an action level cannot be established below
natural background levels.
Plants
When considering the bioavailability of a metal to plants from soils and sediments, it is
generally assumed that both the kinetic rate of supply and the speciation of the metal to either the
root or shoot are highly important. In soils and sediments generally, only a small volume of
water is in contact with the chemical form, and although the proportion of a metal's
concentration in this pore water to the bulk soil/sediment concentration is small, it is this phase
that is directly available to plants. Therefore, pore water chemistry (i.e., metal concentration as
simple inorganic species, organic complexes, or colloid complexes) is most important.
Tools currently used for metal speciation for plants include (1) in-situ measurements
using selective electrodes (Gundersen et al., 1992; Archer et al., 1989; Wehrli et al., 1994);
(2) in-situ collection techniques using diffusive equilibrium thin films (DET) and diffusive
gradient thin films (DOT) followed by laboratory analyses (Davison et al., 1991, 1994; Davison
and Zhang, 1994; Zhang et al., 1995); and (3) equilibrium models ( SOILCHEM) (Sposito and
Coves, 1988).
AX7.1.1.3 Tools for Bulk Lead Quantification and Speciation
Bulk Quantification
The major analytical methods most commonly used for bulk analyses outlined in the 1986
Lead ACQD included:
• Atomic Absorption Spectrometry (AAS)
• Emission Spectrometry (Inductively coupled plasma/atomic emission spectrometry)
• X-ray Fluorescence (XRF)
• Isotope Dilution Mass Spectrometry (ID/MS)
AX7-9
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• Colorimetric
• Electrochemical (anodic stripping voltametry and differential pulse polarography).
The choice of analytical method today for bulk quantification is generally ICP/AES or
ICP/MS (U.S. Environmental Protection Agency, 2001). Since 1986, numerous SRMs have
been developed for Pb (Table AX7-1.1.2), and several significant technological improvements
have been developed.
Table AX7-1.1.2. National Institute of Standards and Technology Lead SRMs
NIST SRM
2710
2711
2709
2587
2586
2783
1648
1649a
2584
2583
1515
1575
Medium
Soil
Soil
Soil
Soil (paint)
Soil (paint)
Filter (PM2 5)
Urban participate
Urban dust
Indoor dust
Indoor dust
Apple leaves
Pine needles
Mean Pb
mg/kg
5532
1162
18.9
3242
432
317
6550
12,400
9761
85.9
0.47
0.167
Modern spectrometry systems have replaced photomultiplier tubes with a charge-coupled
device (CCD). The CCD is a camera that can detect the entire light spectrum (>70,000 lines)
from 160 to 785 nm. This allows for the simultaneous measurement of all elements, as well as
any interfering lines (a productivity increase), and increases precision. The detection limit for Pb
in clean samples can now be as low as 40 ppb.
AX7-10
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Modern ICP/AES systems offer a choice of either axial viewed plasma (horizontal),
which provides greater sensitivity (DL= 0.8 jig Pb/L), or radial (vertical) viewed plasma, which
performs best with high total dissolved samples (DL = 5.0 jig Pb/L).
The development of reaction or collision cells have expanded the capabilities of ICP/MS
and lowered detection limits for many elements that were difficult to analyze because of
interferences such as Se, As, Ti, Zn, Ca, Fe, and Cr. The cells provide efficient interference
(isobaric, polyatomic, and argide) removal independent of the analyte and sample matrix by
using various reaction gases (H2, He, MT?), eliminating the need for interference correction
equations.
Speciation Tools
A wide variety of analytical and chemical techniques have been used to characterize a
metal's speciation (as defined above) in various media (Hunt et al., 1992; Manceau et al., 1996,
2000a; Welter et al., 1999; Szulczewski et al., 1997; Isaure et. al., 2002; Lumsdon and Evans,
1995; Gupta and Chen, 1975; Ma and Uren, 1995; Charlatchka et al., 1997). Perhaps the most
important factor that one must keep in mind in selecting a technique is that, when dealing with
metal-contaminated media, one is most often looking for the proverbial "needle in a haystack."
Therefore, the speciation technique must not only provide the information outlined above, but it
must also determine that information from a medium that contains very little of the metal.
As illustrated in Figure AX7-1.1.5, for a Pb-contaminated soil, less than 1% (modally) of a
single species can be responsible for a bulk metal's concentration above an action level. This
factor is even more significant for other metals (i.e., As, Cd, or Hg) were action levels are often
below 100 mg/kg.
Of the techniques tested (physicochemical, extractive, and theoretical), the tools that have
been used most often to evaluate speciation for particle-bound metal include X-ray absorption
spectroscopy (XAS), X-ray diffraction (XRD), particle induced X-ray emission (PIXE and
jiPIXE), electron probe microanalysis (EPMA), secondary ion mass spectrometry (SIMS),
X-ray photoelectron spectroscopy (XPS), sequential extractions, and single chemical extractions.
The tools that have been used most often to evaluate speciation for metal particles in solution
include the following computer-based models: MINTEQL, REDEQL2, ECOSAT, MINTEQA2,
HYDRAQL, PHREEQE, and WATEQ4F. These tools are briefly described below.
AX7-11
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Lead Form vs Bulk Lead
SLAG
o>
i/)
re
.a
0.
ro
T3
O
0 2500 5000 7500 10000
Bulk Pb mg/kg
Figure AX7-1.1.5. Bulk lead versus single species modality. Shaded area represents
typical soil-lead concentrations found at remediation sites in the
western United States.
Particle-Bound Metal
Direct Approaches
Over the past decade, numerous advances in materials science have led to the
development of a wide range in analytical tools for the determination of metal concentration,
bonding, and valance of individual particles on a scale that can be considered useful for the
speciation of environmentally important materials (i.e., soils, wastes, sediments, and dust).
This review will provide the reader with a brief description of these techniques, including their
benefits, limitations (cost, availability, sample preparation, resolution), and usability as well as
references to current applications. Although most of these tools are scientifically sound and
offer important information on the mechanistic understanding of metal occurrence and behavior,
only a few currently provide useful information on metal bioavailability at a "site" level.
However, one may still find other techniques essential to a detailed characterization of a selected
AX7-12
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material to describe the chemical or kinetic factors controlling a metal's release, transport,
and/or exposure.
X-Ray absorption Spectroscopy (XAS). X-ray absorption spectroscopy (XAS) is a
powerful technique using the tunable, monochromatic (white light) X-rays produced by a
synchrotron (2-4 GeV) to record oscillations in atomic absorption within a few 100 GeV of an
element's absorption edge. Spectra provide information on both chemical state and atomic
structure. Measurements are theoretically available for all elements and are not surface-sensitive
nor sample-sensitive (i.e., gases, liquids, solids, and amorphous materials are testable).
High-energy spectra within 30 eV of the edge, termed XANES (X-ray absorption near
edge structure spectroscopy (Fendorf et al., 1994; Maginn, 1998), are particularly suited for
determination and quantification (10 to 100 ppm) of metal in a particular oxidation state
(Szulczewski et al., 1997; Shaffer et al., 2001; Dupont et al., 2002). The lower-energy spectra
persist some 100 eV above the edge. These oscillations are termed EXAFS (extended X-ray
absorption fine structure) and are more commonly used for speciation analyses (Welter et al.,
1999; Manceau et al., 1996, 2000a; Isaure et al., 2002).
The main limitations to XAS techniques are (1) the lack of spatial resolution; (2) XAS
techniques provide only a weighted average signal of structural configurations, providing
information on the predominant form of the metal, while minor species, which may be more
bioavailable, can be overlooked; (3) access to synchrotrons is limited and the beam time required
to conduct a site investigation would be prohibitive; (4) a large spectral library must be
developed; (5) generally, poor fits to solution models are achieved when the compound list is
large; and (6) high atomic number elements have masking problems based on compound density.
X-Ray Diffraction (XRD). In X-ray diffraction, a monochromatic Fe, Mo, Cr, Co, W, or
Cu X-ray beam rotates about a finely powdered sample and is reflected off the interplanar
spacings of all crystalline compounds in the sample, fulfilling Bragg's law (nX = 2dsin0). The
identification of a species from this pattern is based upon the position of the lines (in terms of
0 or 20) and their intensities as recorded by an X-ray detector. The diffraction angle (20) is
determined by the spacing between a particular set of atomic planes. Identification of the species
is empirical, and current available databases contain more than 53,000 compounds.
If a sample contains multiple compounds, interpretation becomes more difficult and
computer-matching programs are essential. In some instances, by measuring the intensity of the
AX7-13
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diffraction lines and comparing them to standards, it is possible to quantitatively analyze
crystalline mixtures; however, if the species is a hydrated form or has a preferred orientation,
this method is only semiquantitative at best. Since this technique represents a bulk analysis,
no particle size or lability information can be extracted from the patterns.
Particle InducedX-Ray Emission (PIXE and juPIXE). Particle induced X-ray emission
(PIXE) uses a beam, ~4 jim in diameter, of heavy charged particles (generally He) to irradiate
the sample. The resulting characteristic X-rays are emitted and detected in a similar manner as
XRF, using Si-Li detectors. Particles generated from a small accelerator or cyclotron, with a
potential of 2 to 4 MeV, are commonly used. Detection limits on the order of 1 mg/kg are
achieved on thin-film samples. Disadvantages to its use for speciation include (1) only a small
volume of material can be analyzed (1 to 2 mg/cm2); (2) no particle size information is provided;
(3) peak overlaps associated with Si-Li detectors limit identification of species; (4) limited
availability; and (5) high cost. For a further review of PIXE analysis and applications, see
Maenhaut(1987).
Electron Probe Microanalysis (EPMA). Electron probe microanalysis uses a finely
focused (1 |im) electron beam (generated by an electron gun operating at a 2 to 30 kV
accelerating voltage and pico/nanoamp currents) to produce a combination of characteristic
X-rays for elemental quantification along with secondary electrons and/or backscatter electrons
for visual inspection of a sample. Elements from beryllium to uranium can be nondestructively
analyzed at the 50-ppm level with limited sample preparation. X-ray spectra can be rapidly
acquired using either wavelength dispersive spectrometers (WDS) or energy dispersive
spectrometers (EDS).
With WDS, a set of diffracting crystals, of known d-spacing, revolve in tandem with a
gas-filled proportional counter inside the spectrometer housing so that Bragg's law is satisfied
and a particular wavelength can be focused. Photon energy pulses reflecting off the crystal are
collected for an individual elemental line by the counter as a first approximation to
concentration. For quantitative analysis, these intensities are compared to those of known
standards and must be corrected for background, dead time, and elemental interactions (ZAF)
(Goldstein et al., 1992). ZAF correction is in reference to the three components of matrix
effects: atomic number (Z), absorption (A), and fluorescence (F).
AX7-14
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With EDS, a single Si-Li crystal detector is used in conjunction with a multichannel
analog-digital converter (ADC) to sort electrical pulses (with heights approximately proportional
to the quantum energy of the photon that generated them), producing a spectrum of energy
(wavelength) versus counts. The net area under a particular peak (elemental line) is proportional
to its concentration in the sample. For quantitative analyses, corrections similar to WDS analysis
must be performed. Although EDS detectors are more efficient than WDS, detection limits are
significantly greater (-1000 ppm), because of elevated backgrounds and peak overlaps.
For speciation analysis, the EDS system must NEVER be used as the primary detector, as
numerous errors in species identification are often made. These are generally the result of
higher-order X-ray line overlaps.
This technique has been routinely used for site characterizations (Linton et al., 1980;
Hunt et al., 1992; Camp, Dresser, and McKee (COM), 1994; U.S. Environmental Protection
Agency, 2002). Currently this technique offers the most complete data package on metal
speciation than any of the other tools. The method is relatively fast and inexpensive, available,
and provides all of the required information for bioavailability assessments (i.e., particle size,
species, lability, and sourcing). A number of limitations still need to be addressed including:
(1) its inability to quickly isolate a statistically significant population of particles in soils with
low bulk metal concentrations (<50 mg/kg), meaning that for some metals with low
concentrations of concern (i.e., Cd, Mo, Sb, Se), this method may be less useful; (2) the more
volatile metals (i.e., Hg, Tl) are often volatilized under the electron beam or lost during sample
preparation.
Secondary Ion Mass Spectrometry (SIMS). Secondary ion mass spectrometry (also known
as ion microprobes or ion probes) is a well-known technique, primarily surface focused, that uses
a 0.5 to 20 kV O, Ar, Ga, In, or Cs ion beam in bombarding (sputtering) the surface of a sample
while emitting secondary ions that are detected by either quadrapole, time-of-flight (TOF), or
magnetic sector mass spectrometers. Sensitivity is very high, in the ppb range for elements
hydrogen to uranium, providing quantitative results on elemental or isotopic metals and organic
compounds. With the advent of liquid metal (In and Ga) ion beams, beam sizes of less than
1 |im are possible, although 20 jim is more commonly used.
AX7-15
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The major disadvantage of SIMS to species identification is that each element or isotope
must be tuned and analyzed sequentially. This makes the identification of a metal form highly
time-consuming and, thus, the characterization of a multiphase medium impractical.
X-Ray Photoelectron Spectroscopy (XPS). X-ray photoelectron spectroscopy or ESC A
(electron spectroscopy for chemical analysis, as it was previously known) is a classical surface,
10 to 50 A in depth, analytical technique for determining qualitative elemental concentrations of
elements greater than He in atomic number and provides limited structural and oxidation state
information. In XPS, the high-energy (15 kV) electrons are typically produced from a dual-
anode (Al-Mg) X-ray tube. The excitation or photoionization of atoms within the near surface of
the specimen emit a spectrum of photoelectrons. The measured binding energy is characteristic
of the individual atom to which it was bound. Monochromatic sources are often employed to
improve energy resolution, allowing one to infer oxidation states of elements or structure of
compounds (organic and inorganic) by means of small chemical shifts in binding energies
(Hercules, 1970). The major disadvantages of XPS for environmental speciation studies is its
poor sensitivity, especially in complex matrices and its large, 100-200 jim, spatial resolution.
The direct speciation techniques discussed above are summarized in Table AX7-1.1.3.
Indirect Approaches
A more indirect approach to speciation than the methods previously described include the
functional or operational extraction techniques that have been used extensively over the years
(Tessier et al., 1979; Tessier and Campbell, 1988; Gupta and Chen, 1975). These methods use
either a single or sequential extraction procedure to release species associated with a particular
metal within the media. Single chemical extractions are generally used to determine the
bioavailable amount of metal in a functional class: water-soluble, exchangeable, organically
bound, Fe-Mn bound, or insoluble.
In a similar approach, sequential extractions treat a sample with a succession of reagents
intended to specifically dissolve different, less available phases. Many of these techniques have
been proposed, most of which are a variation on the classical method of Tessier et al. (1979),
in which metal associated with exchangeable, carbonate-bound, Fe-Mn bound, organically
bound, and residual species can be determined. Beckett (1989), Kheboian and Bauer (1987),
and Foerstner (1987) provide excellent reviews on the use and abuse of extractions. These
AX7-16
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Table AX7-1.1.3. Characteristics for Direct Speciation Techniques
X
Tools
XRD
EMPA
SIMS
XPS
XAS
PIXIE
£
2
r:
J
'S
a.
&c
No
Yes
No
No
No
No
—
t«
ii
'S
S.
Cfl
No
Yes
Yes
No
No
No
a
^
> |
I
8.
Cfl
No
Yes+
No
Yes
Yes
No
a
•3
a
•1
'i
in
No
No
No
Yes
Yes
No
0
ix •£
?!
o
U
No#
Yes
Yes*
Yes*
Yes*
Yes
1>
y
x a
'0 -a
O fl
— =
^*
No
Yes?
Yes**
Yes**
Yes**
Yes**
— £>
"S *
i|
u ^
•S O
G^
No
B-U
Li-U
H-U
He-U
B-U
o w
"S. ^
2 2
O ^
5« ^3
M u
No
No***
Yes
No
No
No
S3 "^"
a> .C
I *
W c^
3-4vol%
50ppm
Ippb
wt.%
ppb
lOppm
B
O
15
"3
&
Bulk
0.5-1 um
10 um
100 um
1 um
4 um
^
^3
rt 0
1 u
-5
1 $
2 $$
4 $$$
2 $$
5 $$$$
$$$$
* Technique requires each element be tuned and standardized, requiring unreasonable time limits.
** Techniques designed and tested only on simple systems. Multiple species require lengthy analytical times and data reduction.
*** Limited when combined with ICP/MS/LA.
# Identifies crystalline compounds and stoichiometric compositions only.
1 Technique has limitations based on particle counting statistics.
+ Valance determined by charge balance of complete analyses.
-------
techniques can be useful in a study of metal uptake in plants, where transfer takes place
predominately via a solution phase. However, one must keep in mind that they are not
"selective" in metal species, give no particle size information and, above all, these teachable
fractions have never been correlated to bioavailability.
Solution Speciation Using Computer-Based Models. Computer-based models are either
based upon equilibrium constants or upon Gibb's free energy values in determining metal
speciation from solution chemistry conditions (concentration, pH, Eh, organic complexes,
adsorption/desorption sites, and temperature). Both approaches are subject to mass balance and
equilibrium conditions. These models have undergone a great deal of development in recent
years, as reliable thermodynamic data has become available and can provide some predictive
estimates of metal behavior. A good review of these models and their applications is provided
by Lumsdon and Evans (1995).
Speciation can be controlled by simple reactions; however, in many cases, particularly in
contaminated media, their state of equilibrium and reversibility are unknown. In addition, these
models suffer from other limitations such as a lack of reliable thermodynamic data on relevant
species, inadequacies in models to correct for high ionic strength, reaction kinetics are poorly
known, and complex reactions with co-precipitation/adsorption are not modeled.
The first limitation is perhaps the most significant for contaminated media. For example,
none of the models would predict the common, anthropogenic, Pb phases, i.e., paint, solder,
and slag.
AX7.1.1.4 Biotic Ligand Model
The biotic ligand model (BLM) is an equilibrium-based conceptual model that has been
incorporated into regulatory agencies guidelines (including the EPA) to predict effects of metals
primarily on aquatic biota and to aid in the understanding of their interactions with biological
surfaces (see Annex Section AX7.2.1.3).
Because of assumed similarities in mechanisms of toxicity between aquatic and terrestrial
organisms, it is likely that the BLM approach as developed for the aquatic compartment may also
be applicable to the terrestrial environment. Recent research has been directed toward extending
the BLM to predict metal toxicity in soils (Steenbergen et al., 2005). Steenbergen et al. (2005)
pointed out that, until recently, the BLM concept has not been applied to predict toxicity to soil
AX7-18
-------
organisms. The authors believe there may be two reasons for this. First, metal uptake routes in
soils are generally more complex than those in water, because exposure via pore water and
exposure via ingestion of soil particles may, in principle, both be important. Second, it remains
very difficult to univariately control the composition of the soil pore water and the metal
concentrations in the pore water, due to re-equilibration of the system following modification of
any of the soil properties (including addition of metal salts).
Steenbergen et al. (2005) assessed acute copper toxicity to the earthworm Aporrectodea
caliginosa using the BLM. To overcome the aforementioned problems inherent in soil toxicity
tests they developed an artificial flow-through exposure system consisting of an inert quartz sand
matrix and a nutrient solution, of which the composition was univariately modified. Thus, the
obstacles in employing the BLM to terrestrial ecosystems seem to be surmountable, and future
research may provide useful information on Pb bioavailability and toxicity to terrestrial
organisms.
AX7.1.1.5 Soil Amendments
The removal of contaminated soil to mitigate exposure of terrestrial ecosystem
components to Pb can often present both economic and logistic problems. Because of this,
recent studies have focused on in situ methodologies to lower soil-Pb RBA (Brown et al.,
2003a,b). To date, the most common methods studied include the addition of soil amendments
in an effort either to lower the solubility of the Pb form or to provide sorbtion sites for fixation of
pore-water Pb. These amendments typically fall within the categories of phosphate, biosolid,
and Al/Fe/Mn-oxide amendments.
Phosphate Amendments
Phosphate amendments have been studied extensively and, in some cases, offer the most
promising results (Brown et al., 1999; Ryan et al., 2001; Cotter-Howells and Caporn, 1996;
Hettiarachchi et al., 2001, 2003; Rabinowitz, 1993; Yang et al., 2001; Ma et al., 1995). Research
in this area stems from early work by Nriagu (1973) and Cotter-Howells and Caporn (1996), who
pointed out the very low solubilities for many Pb-phosphates (Ksp !27 to !66), particularly
chloropyromorphite [Pbs^O/OsCl]. The quest to transform soluble Pb mineralogical forms into
chloropyromorthite continues to be the primary focus of most studies. Sources of phosphorous
AX7-19
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have included phosphoric acid (HjPO/t), triple-super phosphate (TSP), phosphate rock, and/or
hydroxyapatite (HA). Various studies have combined one or more of these phosphorous sources
with or without lime, iron, and/or manganese in an attempt to enhance amendment qualities.
Most amendments are formulated to contain between 0.5 and 1.0% phosphorous by weight.
They are then either applied wet or dry and then mixed or left unmixed with the contaminated
soil. Success of phosphate amendments has been variable, and the degree of success appears to
depend on available phosphorous and the dissolution rate of the original Pb species.
A number of potentially significant problems associated with phosphate amendments have
been recognized, including both phyto- and earthworm toxicity (Ownby et al., 2005; Cao et al.,
2002; and Rusek and Marshall, 2000). Both of these toxicities are primarily associated with very
high applications of phosphorous and/or decreased soil pH. Indications of phytotoxicity are
often balanced by studies such as Zhu et al. (2004) that illustrate a 50 to 70% reduction in shoot-
root uptake of Pb in phosphate-amended soils. Additionally, the added phosphate poses the
potential risk of eutrophication of nearby waterways from soil runoff. Finally, Pb-contaminated
soils from the extractive metals industry or agricultural sites often have elevated concentrations
of arsenic. It has been shown (Impellitteri, 2005; Smith et al., 2002; Chaney and Ryan, 1994;
and Ruby et al., 1994) that the addition of phosphate to such soils would enhance arsenic
mobility (potentially moving arsenic down into the groundwater) through competitive anion
exchange. Some data (Lenoble et al., 2005) indicate that if one could amend arsenic and Pb
contaminated soils with iron(III) phosphate this problem can be mitigated, however the increased
concentrations of both phosphate and iron still exclude the application when drinking water is an
issue.
Biosolid Amendments
Historically, biosolids have been used in the restoration of coal mines (Haering et al.,
2000; Sopper, 1993). More recently, workers have demonstrated the feasibility of their use in
the restoration of mine tailings (Brown et al., 2003a), and urban soils (Brown et al., 2003b;
Farfel et al., 2005). Mine tailings are inherently difficult to remediate in that they pose numerous
obstacles to plant growth. They are most often (1) acidic; (2) high in metal content, thus prone to
phytotoxicity; (3) very low in organic content; and (4) deficient in macro- and micronutrients.
AX7-20
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Stabilization (i.e., the establishment of a vegetative cover) of these environments is essential to
the control of metal exposure or migration from soil/dust and groundwater pathways.
At Bunker Hill, ID, Brown et al. (2003b) demonstrated that a mixture of high nitrogen
biosolids and wood pulp or ash, when surface applied at a rate of approximately 50 and
220 tons/ha, respectively, increased soil pH from 6.8 to approximately 8.0, increased plant
biomass from 0.01 mg/ha to more than 3.4 tons/ha, and resulted in a healthy plant cover within
2 years. Metal mobility was more difficult to evaluate. Plant concentrations of Zn and Cd were
generally normal for the first 2 years of the study; however, Pb concentrations in vegetation
dramatically increased two to three times in the first year. Additionally, macronutrients (Ca, K,
and Mg) decreased in plant tissue.
Urban soils, whether contaminated from smelting, paint, auto emissions, or industrial
activity, are often contaminated with Pb (Agency for Toxic Substances and Disease Registry
[ATSDR], 1988) and can be a significant pathway to elevated child blood Pb levels (Angle et al..
1974). Typically, contaminated residential soils are replaced under Superfund rules. However,
urban soils are less likely to be remediated unless a particular facility is identified as the
contaminate source. Application of biosolids to such soils may be a cost-effective means for
individuals or communities to lower Pb RBAs.
A field study by Farfel et al. (2005) using the commercial biosolid ORGO found that,
over a 1-year period, Pb in the dripline soils of one residence had reduced RBAs by -60%.
However, soils throughout the remainder of the yard showed either no reduction in RBA or a
slight increase. A more complex study was conducted by Brown et al. (2003a) on an urban
dripline soil in the lab. The study used an assortment of locally derived biosolids (raw, ashed,
high-Fe compost, and compost) with and without lime. All amendments were incubated with
approximately 10% biosolids for a little more than 30 days. In vitro and in vivo data both
indicated a 3 to 54% reduction in Pb RBA, with the high-Fe compost providing the greatest
reduction.
As with phosphate amendments, problems with biosolid application have also been
documented. Studies have shown that metal transport is significantly accelerated in soils
amended with biosolids (Al-Wabel et al., 2002; McBride et al., 1997, 1999; Lamy et al., 1993;
Richards et al., 1998, 2000). Some of these studies indicate that metal concentrations in soil
solutions up to 80 cm below the amended surface increased by 3- to 20-fold in concentration up
AX7-21
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to 15 years after biosolid application. The increase in metal transport is likely the result of
elevated dissolved organic carbon (DOC) in the amended soil. Anodic stripping voltammetry
has indicated that very low percentages (2 to 18%) of the soluble metals are present as ionic or
inorganic complexes (McBride, 1999; Al-Wabel et al., 2002).
AX7.1.2 Distribution of Atmospherically Delivered Lead in
Terrestrial Ecosystems
The 1986 Lead AQCD (U.S. Environmental Protection Agency, 1986a) contains only a
few minor sections that detail the speciation, distribution, and behavior of atmospherically
delivered Pb in terrestrial ecosystems. The document concluded that the majority of Pb in the
atmosphere at that time was from gasoline consumption: of the 34,881 tons of Pb emitted to the
atmosphere in 1984, 89% was from gasoline use and minor amounts were from waste oil
combustion, iron and steel production, and smelting. Lead in the atmosphere today, however, is
not primarily from leaded-gasoline consumption, but results largely from iron and steel
foundaries, boilers and process heaters, the combustion of fossil fuels in automobiles, trucks,
airplanes, and ships, and other industrial processes (Table 2-8, Polissar et al., 2001; Newhook
et al., 2003). The emission source can determine the species of Pb that are delivered to terrestrial
ecosystems. For example, Pb species emitted from automobile exhaust is dominated by
particulate Pb halides and double salts with ammonium halides (e.g., PbBrCl, PbBrCbNFLCl),
while Pb emitted from smelters is dominated by Pb-sulfur species (Habibi, 1973). The halides
from automobile exhaust break down rapidly in the atmosphere, possibly via reactions with
atmospheric acids (Biggins and Harrison, 1979). Lead phases in the atmosphere, and
presumably the compounds delivered to the surface of the earth (i.e., to vegetation and soils),
are suspected to be in the form of PbSO4, PbS, and PbO (Olson and Skogerboe, 1975; Clevenger
et al., 1991; Utsunomiya et al., 2004).
There are conflicting reports of how atmospherically derived Pb specifically behaves in
surface soils. This disagreement may represent the natural variability of the biogeochemical
behavior of Pb in different terrestrial systems, the different Pb sources, or it may be a function of
the different analytical methods employed. The importance of humic and fulvic acids (Zimdahl
and Skogerboe, 1977; Gamble et al., 1983) and hydrous Mn- and Fe-oxides (Miller and McFee,
1983) for scavenging Pb in soils are discussed in some detail in the 1986 Lead AQCD. Nriagu
AX7-22
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(1974) used thermodynamics to argue that Pb-orthophosphates (e.g., pyromorphite) represented
the most stable Pb phase in many soils and sediments. He further suggested that, because of the
extremely low solubility of Pb-phosphate minerals, Pb deposition could potentially reduce
phosphorous availability. Olson and Skogerboe (1975) reported that solid-phase PbSC>4
dominated gasoline-derived Pb speciationin surface soils from Colorado, Missouri, and Chicago,
while Santillan-Medrano and Jurinak (1975) suggested that Pb(OH)2, Pb(PO4)2, and PbCO3
could regulate Pb speciation in soils. However, insoluble organic material can bind strongly to
Pb and prevent many inorganic phases from ever forming in soils (Zimdahl and Skogerboe,
1977).
The vertical distribution and mobility of atmospheric Pb in soils was poorly documented
prior to 1986. Chapter 6 of the 1986 AQCD cited a few references suggesting that atmospheric
Pb is retained in the upper 5 cm of soil (Reaves and Berrow, 1984). Techniques using radiogenic
Pb isotopes had been developed to discern between gasoline-derived Pb and natural, geogenic
(native) Pb, but these techniques were mostly applied to sediments (Shirahata et al., 1980) prior
to the 1986 Lead AQCD. Without using these techniques, accurate determinations of the depth-
distribution and potential migration velocities for atmospherically delivered Pb in soils were
largely unavailable.
Several technological advances, combined with the expansion of existing technologies
after 1986 resulted in the publication of a large body of literature detailing the speciation,
distribution, and geochemical behavior of gasoline-derived Pb in the terrestrial environment.
Most notably, the development of selective chemical extraction (SCE) procedures as a rapid and
inexpensive means for partitioning Pb into different soil and sediment phases (e.g., Pb-oxides,
Pb-humate, etc.) has been exploited by a number of researchers (Tessier et al., 1979; Johnson
and Petras, 1998; Ho and Evans, 2000; Scheckel et al., 2003). Also, since 1986, several workers
have exploited synchrotron-based XAS in order to probe the electron coordination environment
of Pb in soils, organic matter, organisms, and sediments (Manceau et al., 1996; Xia et al., 1997;
Trivedi et al., 2003). X-ray absorption studies can be used for the in-situ determination of the
valence state of Pb and can be used to quantify Pb speciation in a variety of untreated samples.
Biosensors, which are a relatively new technology coupling biological material, such as an
enzyme, with a transducer, offer a new, simple, and inexpensive means for quantifying available
Pb in ecosystems (Verma and Singh, 2005). Advances in voltammetric, diffusive gradients in
AX7-23
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thin films (DOT), and TCP techniques have also increased the abilities of researchers to quantify
Pb phases in solutions (Berbel et al., 2001; Scally et al., 2003). In addition to the development of
techniques for describing and quantifying Pb species in the soils and solutions, researchers have
used radiogenic Pb isotopes (206Pb, 207Pb, 208Pb) to quantify the distribution, speciation, and
transport of anthropogenic Pb in soil profiles and in vegetation (Bindler et al., 1999; Erel et al.,
2001; Kaste et al., 2003; Klaminder et al., 2005).
Over the past several decades, workers have also developed time-series data for Pb in
precipitation, vegetation, organic horizons, mineral soils, and surface waters. Since
atmospherically delivered Pb often comprises a significant fraction of the "labile" Pb (i.e., Pb not
associated with primary minerals), these data have been useful for developing transport and
residence time models of Pb in different terrestrial reservoirs (Friedland et al., 1992; Miller and
Friedland, 1994; Johnson et al., 1995a; Wang and Benoit, 1997). Overall, a significant amount
of research has been published on the distribution, speciation, and behavior of anthropogenic Pb
in the terrestrial environment since 1986. However, certain specific details on the behavior of Pb
in the terrestrial environment and its potential effects on soil microorganisms remain elusive.
AX7.1.2.1 Speciation of Atmospherically-delivered Lead in Terrestrial Ecosystems
Lead in the Solid Phases
Lead can enter terrestrial ecosystems through natural rock weathering and by a variety of
anthropogenic pathways. These different source terms control the species of Pb that is
introduced into the terrestrial environment. While Pb is highly concentrated (percent level) in
certain hydrothermal sulfide deposits (e.g., PbS) that are disseminated throughout parts of the
upper crust, these occurrences are relatively rare. Therefore, the occurrence of Pb as a minor
constituent of rocks (ppm level), particularly granites, rhyelites, and argillaceous sedimentary
rocks is the more pertinent source term for the vast majority of terrestrial ecosystems. During
the hydrolysis and oxidation of Pb-containing minerals, divalent Pb is released to the soil
solution where it is rapidly fixed by organic matter and secondary mineral phases (Kabata-
Pendias and Pendias, 1992). The geochemical form of natural Pb in terrestrial ecosystems will
be strongly controlled by soil type (Emmanuel and Erel, 2002). In contrast, anthropogenically
introduced Pb has a variety of different geochemical forms, depending on the specific source.
While Pb in soils from battery reclamation areas can be in the form of PbSO4 or PbSiOs, Pb in
AX7-24
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soils from shooting ranges and paint spills is commonly found as PbO and a variety of Pb
carbonates (Vantelon et al., 2005; Laperche et al., 1996; Manceau et al., 1996). Atmospherically
delivered Pb resulting from fossil fuel combustion is typically introduced into terrestrial
ecosystems as Pb-sulfur compounds and Pb oxides (Olson and Skogerboe, 1975; Clevenger
et al., 1991; Utsunomiya et al., 2004). After deposition, Pb species are likely transformed.
Although the specific factors that control the speciation of anthropogenic Pb speciation in soils
are not well understood, there are many studies that have partitioned Pb into its different
geochemical phases. A thorough understanding of Pb speciation is critical in order to predict
potential mobility and bioavailability (see Section AX7.1.1).
Selective chemical extractions have been employed extensively over the past 20 years for
quantifying amounts of a particular metal phase (e.g., PbS, Pb-humate, Pb-Fe/Mn-oxide) present
in soil or sediment rather than total metal concentration. Sometimes selective chemical
extractions are applied sequentially to a particular sample. For example, the exchangeable metal
fraction is removed from the soil using a weak acid or salt solution (e.g., BaCb), followed
immediately by an extraction targeting organic matter (e.g., H2O2 or NaOCl), further followed by
an extraction targeting secondary iron oxides (e.g., NF^OH-HCl), and finally, a strong reagent
cocktail (e.g., HNCVHCl-HF) targets primary minerals. Tessier et al. (1979) developed this
technique. More recently, this technique has been modified and developed specifically for
different metals and different types of materials (Keon et al., 2001). Alternatively, batch-style
selective chemical extractions have been used on soils and sediments to avoid the problems
associated with nonselective reagents (Johnson and Petras, 1998). Selective extractions can be a
relatively rapid, simple, and inexpensive means for determining metal phases in soils and
sediments, and the generated data can be linked to potential mobility and bioavailability of the
metal (Tessier and Campbell, 1987). However, some problems persist with the selective
extraction technique. First, extractions are rarely specific to a single phase. For example, while
H2O2 is often used to remove metals bound to organic matter in soils, others have demonstrated
that this reagent destroys clay minerals and sulfides (Ryan et al., 2002). Peroxide solutions may
also be inefficient in removing metals bound to humic acids, and in fact could potentially result
in the precipitation of metal-humate substances. In addition to the nonselectivity of reagents,
significant metal redistribution has been documented to occur during sequential chemical
extractions (Ho and Evans, 2000; Sulkowski and Hirner, 2006), and many reagents may not
AX7-25
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completely extract targeted phases. While chemical extractions provide some useful information
on metal phases in soil or sediment, the results should be treated as "operationally defined," e.g.,
"H2O2-liberated Pb" rather than "organic Pb."
Lead forms strong coordination complexes with oxygen on mineral surfaces and organic
matter functional groups (Abd-Elfattah and Wada, 1981), because of its high electronegativity
and hydrolysis constant. Therefore, Pb is generally not readily exchangeable, i.e., the amount of
Pb removed from soils by dilute acid or salts is usually less that 10% (Karamanos et al., 1976;
Sposito et al., 1982; Miller and McFee, 1983; Johnson and Petras, 1998; Bacon and Hewitt,
2005). Lead is typically adsorbed to organic and inorganic soil particles strongly via inner-
sphere adsorption (Xia et al., 1997; Bargar et al., 1997a,b, 1998). Kaste et al. (2005) found that a
single extract of 0.02 M HC1 removed 15% or less Pb in organic horizons from a montane forest
in New Hampshire. The fact that relatively concentrated acids, reducing agents, oxidizing
agents, or chelating agents are required to liberate the majority of Pb from soils is used as one
line of evidence that Pb migration and uptake by plants in soils is expected to be low.
Lead that is "organically bound" in soils is typically quantified by extractions that
dissolve/disperse or destroy organic matter. The former approach often employs an alkaline
solution (NaOH), which deprotonates organic matter functional groups, or a phosphate solution,
which chelates structural cations. Extractions used to destroy organic matter often rely on H2O2
or NaOCl. Both organic and mineral horizons typically have significant Pb in this soil phase.
Miller and McFee (1983) used Na4P2O7 to extract organically bound Pb from the upper 2.5 cm of
soils sampled from northwestern Indiana. They found that organically bound Pb accounted for
between 25 and 50% of the total Pb present in the sampled topsoils. Jersak et al. (1997), Johnson
and Petras (1998), and Kaste et al. (2005) selectively extracted Pb from spodosols from the
northeastern United States. Using acidified H2O2, Jersak et al. (1997) found that very little
(<10 %) of the Pb in mineral soils (E, B, C) sampled from New York and Vermont was organic.
Johnson and Petras (1998) used K4P2Oy to quantify organically bound Pb in the Oa horizon and
in mineral soils from the Hubbard Brook Experimental Forest in New Hampshire. They reported
that 60% of the total Pb in the Oa horizon was organic and that between 8 and 17% of the total
Pb in the mineral soil was organic. However, in the E, Bh, and Bsl horizons, organically bound
Pb dominated the total "labile" (non-mineral lattice) Pb. Kaste et al. (2005) used selective
chemical extractions on organic horizons from montane forests in Vermont and New Hampshire.
AX7-26
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They found that repeated extractions with NaJ^O? removed between 60 and 100% of the Pb
from their samples. Caution should be used when interpreting the results of pyrophosphate
extractions. Although they are often used to quantify organically bound metals, this reagent can
both disperse and dissolve Fe phases (Jeanroy and Guillet, 1981; Shuman, 1982). Acidified
H2O2has also been reported to destroy and release elements associated with secondary soil
minerals (Papp et al., 1991; Ryan et al., 2002).
Aside from organic forms, Pb is often found to be associated with secondary oxide
minerals in soils. Pb can be partitioned with secondary oxides by a variety of mechanisms,
including (1) simple ion exchange, (2) inner-sphere or outer-sphere adsorption, and (3) co-
precipitation and/or occlusion (Bargar et al., 1997a,b, 1998, 1999). As discussed above, very
little Pb is removed from soil via dilute acid or salt solutions, so adsorption and co-precipitation
are likely the dominant Pb interactions with secondary mineral phases. Reagents used to
quantify this phase are often solutions of EDTA, oxalate, or hydroxylamine hydrochloride (HH).
Miller and McFee (1983) used an EDTA solution followed by an FIH solution to quantify Pb
occluded by Fe and Mn minerals, respectively, in their surface-soil samples from Indiana. They
reported that approximately 30% of the total soil Pb was occluded in Fe minerals, and 5 to 15%
was occluded in Mn phases. In soils from the northeastern United States, Jersak et al. (1997)
used various strengths of HH solutions and concluded that negligible Pb was associated with
Mn-oxides and that 1 to 30% of the Pb was associated with Fe phases in the mineral soils in their
study. Johnson and Petras (1998) reported that no Pb was removed from the Oa horizon at the
Hubbard Brook Experimental Forest (HBEF) by oxalate, but that 5 to 15% of the total Pb in
mineral soils was removed by this extraction, presumably because it was bound to amorphous
oxide minerals. Kaste et al. (2005), however, reported that HH removed 30 to 40% of the Pb
from organic horizons in their study. They concluded that Fe phases were important in
scavenging Pb, even in soil horizons dominated by organic matter.
Synchrotron radiation (X-rays) allows researchers to probe the electron configuration of
metals in untreated soil and sediment samples. This type of analysis has been extremely valuable
for directly determining the coordination environment of Pb in a variety of soils and sediments.
Since different elements have different electron binding energies (Eb), X-rays can be focused in
an energy window specific to a metal of interest. In experiments involving XAS, X-ray energy is
increased until a rapid increase in the amount of absorption occurs; this absorption edge
AX7-27
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represents Eb. The precise energy required to dislodge a core electron from a metal (i.e., Eb) will
be a function of the oxidation state and covalency of the metal. X-ray absorption studies that
focus on the location of the absorption edge are referred to as XANES (X-ray absorption near
edge structure). In the energy region immediately after the absorption edge, X-ray absorption
increases and decreases with a periodicity that represents the wave functions of the ejected
electrons and the constructive and destructive interference with the wave functions of the nearby
atoms. X-ray absorption studies used to investigate the periodicity of the absorption after Eb are
referred to as EXAFS (extended X-ray absorption fine structure). Since the electron
configuration of a Pb atom will be directly governed by its speciation (e.g., Pb bound to organics,
Pb adsorbed to oxide surfaces, PbS, etc.) X-ray absorption studies provide a powerful in-situ
technique for determining speciation without some of the problems associated with chemical
extractions (Bargar et al., 1997a,b, 1998).
Manceau et al. (1996) used EXAFS to study soil contaminated by gasoline-derived Pb in
France and found that the Pb was divalent and complexed to salicylate and catechol-type
functional groups of humic substances. He concluded that the alkyl-tetravalent Pb compounds
that were added to gasoline were relatively unstable and will not dominate the speciation of Pb
fallout from the combustion of leaded gasoline. The binding mechanism of Pb to organics is
primarily inner-sphere adsorption (Xia et al., 1997). DeVolder et al. (2003) used EXAFS to
demonstrate that Pb phases were shifting to the relatively insoluble PbS when contaminated
wetland soils were treated with sulfate. Strawn and Sparks (2000) gave evidence that added Pb
was adsorbed directly onto organic matter in an untreated silt loam, but in the absence of organic
matter (treated with sodium hypochlorite) the added Pb appeared to adsorb instead to some form
of SiC>2. More recent XAS studies have demonstrated the importance of biomineralization of Pb
in soils by bacteria and nematodes (Xia et al., 1997; Templeton et al., 2003a,b; Jackson et al.,
2005). Templeton et al. (2003a,b) demonstrated that biogenic precipitation of pyromorphite was
the dominant source of Pb uptake by Burkholderia cepacia biofilms below pH 4.5. Above pH
4.5, adsorption complexes began to form in addition to Pb mineral precipitation.
In addition to XAS studies of Pb in environmental samples, numerous experimental-based
XAS studies have documented in detail the coordination environment of Pb adsorbed to Fe-
oxides, Mn-oxides, Al-oxides, and clay minerals (Manceau et al., 1996, 2000a,b, 2002; Bargar
et al., 1997a,b, 1998, 1999; Strawn and Sparks, 1999; Trivedi et al., 2003; Chen et al., 2006).
AX7-28
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Bargar et al. (1997a) showed that Pb can adsorb to FeOe octahedra on three different types of
sites: on corners, edges, or faces. Ostergren et al. (2000a,b) showed that the presence of
dissolved carbonate and sulfate increased Pb adsorbtion on goethite. The relative fraction of
corner-sharing complexes can be greatly increased by the presence of these ligands, as bridging
complexes between the metal and the corners are formed (Ostergren et al., 2000a,b).
Furthermore, Elzinga and Sparks showed that the mechanism of Pb sorption to SiO2 surfaces is
pH-dependent. In acid environments (pH < 4) Pb adsorbs largely as an inner-sphere mononulear
complex, but as pH increases, Pb sorption increasingly occurs via the formation of surface-
attached covalent polynuclear Pb species.
Recently, Jackson et al. (2005) used microfocused synchrotron-based X-ray fluorescence
(OSXRF) to detail the distribution of Pb and Cu in the nematode Caenorhabditis elegans. They
found that, while Cu was evenly distributed throughout the bodies of exposed C. elegans, Pb was
concentrated in the anterior pharynx region. Microfocused X-ray diffraction indicated that the
highly concentrated Pb region in the pharynx was actually comprised of the crystalline Pb
mineral, pyromorphite. The authors concluded that C. elegans precipitated pyromorphite in the
pharynx as a defense mechanism to prevent spreading the toxic metal to the rest of the
organism's body. They further suggested that, because of the high turnover rate of nematodes,
biomineralization could play an important role in the speciation of Pb in certain soils.
Lead Solid-solution Partitioning
The concentration of Pb species dissolved in soil solution is probably controlled by some
combination of (a) Pb-mineral solubility equilibria, (b) adsorption reactions of dissolved Pb
phases on inorganic surfaces (e.g., crystalline or amorphous oxides of Al, Fe, Si, Mn, etc.; clay
minerals), and (c) adsorption reactions of dissolved Pb phases on soil organic matter. Dissolved
Pb phases in soil solution can be some combination of Pb2+ and its hydrolysis species, Pb bound
to dissolved organic matter, and Pb complexes with inorganic ligands such as Cl! and SO42!.
Alkaline soils typically have solutions supersaturated with respect to PbCOs, Pb3(CO3)2(OH)2,
Pb(OH)2, Pb3(PO4)2, Pb5(PO4)3(OH), and Pb4O(PO4)2 (Badawy et al., 2002). Pb-phosphate
minerals in particular are very insoluble, and calculations based on thermodynamic data predict
that these phases will control dissolved Pb in soil solution under a variety of conditions (Nriagu,
AX7-29
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1974; Ruby et al., 1994). However, certain chelating agents, such as dissolved organic matter,
can prevent the precipitation of Pb minerals (Lang and Kaupenjohann, 2003).
Using a combination of desorption experiments and XAS, EXAFS, and XANES, Rouff
et al. (2006) found that aging of Pb-calcite suspensions resulted in changes in the solid-phase
distribution of Pb. Increased sorption time can reduce trace metal desorption by enhancing the
stability of surface complexes (Rouff et al., 2005) or by mechanisms involving microporous
diffusion (Backes et al., 1995), recrystallization-induced incorporation into the solid phase
(Ainsworth et al., 1994), and formation and stabilization of surface precipitates (Ford et al.,
1999). For adsorption of Pb to hydrous Fe oxides, goethite, and Pb-contaminated soils, aged
samples show Pb to be reversibly bound, suggesting Pb adsorption primarily to the substrates'
surfaces (Rouff et al., 2006). However, for Pb adsorption to calcite aging played a significant
role due to detection of multiple sorption mechanisms, even for short sorption times (Rouff et al.,
2006). pH also played a role in Pb sorption. Over long sorption periods (60 to 270 days), slow
continuous uptake of Pb occurred at pH 7.3 and 8.2. At pH 9.4, no further uptake occurred with
aging and very little desorption occurred. These results show the importance of contact time and
pH on Pb solid-phase partitioning, particularly in geochemical systems in which calcite may be
the predominant mineralogical constituent.
Soil solution dissolved organic matter content and pH typically have very strong positive
and negative correlations, respectively, with the concentration of dissolved Pb species (Sauve
et al., 1998, 2000a, 2003; Weng et al., 2002; Badawy et al., 2002; Tipping et al., 2003). In the
case of adsorption phenomena, the partitioning of Pb2+ to the solid phase is also controlled by
total metal loading, i.e., high Pb loadings will result in a lower fraction being partitioned to the
solid phase. Sauve et al. (1997, 1998) demonstrated that only a fraction of the total Pb in
solution was actually Pb2+ in soils treated with leaf compost. The fraction of Pb2+ to total
dissolved Pb ranged from <1 to 60%, depending on pH and the availability of Pb-binding
ligands. Nolan et al. (2003) used Donnan dialysis to show that 2.9 to 48.8% of the dissolved Pb
was Pb2+ in pore waters of agricultural and contaminated soils from Australia and the United
States. In acidic soils, Al species can compete for sites on natural organic matter and inhibit Pb
binding to surfaces (Gustafsson et al., 2003).
Differential pulse anodic stripping voltammetry (DPASV) is a technique that is useful for
identifying relatively low concentrations of Pb2+ and has found many applications in adsorption
AX7-30
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and partitioning experiments. This technique has been particularly useful for quantifying the Kd,
or partitioning ratio of Pb in the solid-to-liquid phase (Kd = [total solid-phase metal in mg kgri] /
[dissolved metal in mg L!1]). While the exact Kd value is a function of pH, organic matter
content, substrate type, total metal burden, and concentrations of competing ligands, such studies
typically show that Pb has very strong solid-phase partitioning. Partitioning ratios determined by
DPASV generally range from 103 to 106 in soils in the typical pH range (Sauve et al., 2000b).
Aualiitia and Pickering (1987) used thin film ASV to compare the relative affinity of Pb for
different inorganic particulates. They reported that Mn(IV) oxides completely adsorbed the Pb,
regardless of pH in the range of 3 to 9, and had the highest affinity for Pb in their study. The
adsorption of Pb to pedogenic Fe-oxides, Al-hydroxides, clay minerals, and Fe ores was reported
to be pH-dependent. Sauve et al. (1998) used DPASV to study the effects of organic matter and
pH on Pb adsorption in an orchard soil. They demonstrated that Pb complexation to dissolved
organic matter (DOM) increased Pb solubility, and that 30 to 50% of the dissolved Pb was bound
to DOM at pH 3 to 4, while >80% of the dissolved Pb was bound to DOM at neutral pH. They
concluded that in most soils, Pb in solution would not be found as Pb2+ but as bound to DOM.
Sauve et al. (2000a) compared the relative affinity of Pb2+ for synthetic ferrihydrite, leaf
compost, and secondary oxide minerals collected from soils. They reported that the inorganic
mineral phases were more efficient at lowering the amount of Pb2+ that was available in solution
than the leaf compost. Glover et al. (2002) used DPASV in studying the effects of time and
organic acids on Pb adsorption to goethite. They found that Pb adsorption to geothite was very
rapid, and remained unchanged after a period of about 4 h. Lead desorption was found to be
much slower. The presence of salicylate appeared to increase the amount of Pb that desorbed
from goethite more so than oxalate.
AX7.1.2.2 Tracing the Fate of Atmospherically-delivered Lead in Terrestrial Ecosystems
Radiogenic Pb isotopes offer a powerful tool for separating anthropogenic Pb from natural
Pb derived from mineral weathering (Erel and Patterson, 1994; Erel et al., 1997; Semlali et al.,
2001). This has been particularly useful for studying Pb in mineral soil, where geogenic Pb
often dominates. The three radiogenic stable Pb isotopes (206Pb, 207Pb, and 208Pb) have a
heterogeneous distribution in the earth's crust primarily because of the differences in the half-
lives of their respective parents (238U, Ti/2 = 4.7 x 109 year; 235U, Ti/2 = 0.7 x 109 year; 232Th,
AX7-31
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Ti/2 = 14 x 109 year). The result is that the ore bodies from which anthropogenic Pb are typically
derived are usually enriched in 207Pb relative to 206Pb and 208Pb when compared with Pb found in
granitic rocks. Graney et al. (1995) analyzed a dated core from Lake Erie, and found that the
206pb/207pb yalue in se(jiment deposited in the late 1700s was 1.224, but in 20th-century
sediment, the ratio ranged from 1.223 to 1.197. This shift in the Pb isotopic composition
represents the introduction of a significant amount of anthropogenic Pb into the environment.
Bindler et al. (1999) and Emmanuel and Erel (2002) analyzed the isotopic composition of Pb in
soil profiles in Sweden and the Czech Republic, respectively, and determined that mineral soils
immediately below the organic horizon had a mixture of both anthropogenic and geogenic Pb.
Anthropogenic Pb has been detected relatively deep into the soil profile (>25 cm) in Europe,
presumably this represents very "old"( i.e., pre-1900) Pb (Steinnes and Friedland, 2005).
Erel and Patterson (1994) used radiogenic Pb isotopes to trace the movement of industrial
Pb from topsoils to groundwaters to streams in a remote mountainous region of Yosemite
National Park in California. They calculated that total 20th-century industrial Pb input to their
T^'7
study site was approximately 0.4 g Pb m . Lead concentrations in organic material were highest
in the upper soil horizons, and decreased with depth. During snowmelt, Pb in the snowpack was
mixed with the anthropogenic and geogenic Pb already in the topsoil, and spring melts contained
a mixture of anthropogenic and geogenic paniculate Pb. During base flows, however, 80% of
the Pb export from groundwater and streams was from natural granite weathering (Erel and
Patterson, 1994).
Uranium-238 series 210Pb also provides a tool for tracing atmospherically delivered Pb in
soils. After 222Rn (Ti/2 = 3.8 days) is produced from the decay of 226Ra (Ti/2 = 1600 years), some
fraction of the 222Rn escapes from rocks and soils to the atmosphere. It then decays relatively
rapidly to 210Pb (Ti/2 = 22.3 years), which has a tropospheric residence time of a few weeks
(Koch et al., 1996). Fallout 210Pb is deposited onto forests via wet and dry deposition, similar to
anthropogenic Pb deposition in forests, and is thus useful as a tracer for non-native Pb in soils.
Lead-210 is convenient to use for calculating the residence time of Pb in soil layers, because its
atmospheric and soil fluxes can be assumed to be in steady state at undisturbed sites (Dorr and
Munnich, 1989; Dorr, 1995; Kaste et al., 2003). Atmospheric 210Pb (210Pbex hereafter,210Pb in
"excess" of that supported by 222Rn in the soil) must be calculated by subtracting the amount of
AX7-32
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210Pb formed in soils by the in-situ decay of 222Rn from the total 210Pb (Moore and Poet, 1976;
Nozakietal., 1978).
Benninger et al. (1975) measured fallout 210Pb in soils and streamwater at Hubbard Brook
and at an undisturbed forest in Pennsylvania. They estimated atmospheric 210Pb export in
streamwaters to be <0.02% of the standing 210Pb crop in the organic horizons. They used a
simple steady-state model to calculate the residence time of Pb in the organic horizons to be
5,000 years. This overestimate of the Pb residence time in the organic horizons was likely a
result of the low resolution of their sampling. Since they only sampled the upper 6 cm of soil
and the drainage waters, they did not accurately evaluate the distribution of 210Pb in the soil
column in between. Dorr and Miinnich (1989, 1991) used 210Pb profiles in soils of southern
Germany to evaluate the behavior of atmospherically delivered Pb. They calculated the vertical
velocity of Pb by dividing the relaxation depth (i.e., the depth at which 210Pb activity decreases to
lie, or approximately 37% of its surface value) by the 210Pb mean life of 32 years. They reported
downward transit velocities of atmospherically deposited Pb at 0.89 ± 0.33 mm yearri. The
downward transport of atmospheric Pb was not affected by pH or soil type. However, since Pb
velocities in the soil profile where identical to carbon velocities calculated with 14C, they
concluded that Pb movement in forest soils is probably controlled by carbon transport. Kaste
et al. (2003) used 210Pb to model the response time of atmospherically delivered Pb in the O
horizon at Camel's Hump Mountain in Vermont. They concluded that the forest floor response
time was between 60 and 150 years, depending on vegetation zone and elevation. Using
206Pb:207Pb, they also demonstrated that some gasoline-derived Pb migrated out of the O horizon
and into the mineral soil in the deciduous vegetation zone on the mountain, while all of the
atmospheric Pb was retained in the upper 20 cm of the soil profile. Klaminder et al. (2006) used
210Pb distributions to calculate the residence time of Pb in soils of Northern Sweeden. They
concluded that atmospheric Pb had a residence time of-200 years in the mor layer of mature
forests. They also provided evidence suggesting that forests in an earlier stage of ecological
succession have a much shorter Pb residence time in the mor horizon (<50 years).
Researchers assessing the fate of atmospheric Pb in soils have also relied on repeated
sampling of soils and vegetation for total Pb (e.g., Zhang, 2003). This technique works best
when anthropogenic Pb accounts for the vast majority of total Pb in a particular reservoir.
Johnson et al. (1995a), Yanai et al. (2004), and Friedland et al. (1992) used O horizon (forest
AX7-33
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floor) time-series data to evaluate the movement of gasoline-derived Pb in the soil profile. These
studies have concluded that the distribution of Pb in the upper soil horizons has changed over the
past few decades. Yanai et al. (2004) documented a decline in Pb from the Oie horizon between
the late 1970s to the early 1990s in remote forest soils in New Hampshire. Johnson et al. (1995a)
and Friedland et al. (1992) demonstrated that some fraction of Pb had moved from the O horizon
to the mineral soil during the 1980s at Hubbard Brook and at selected remote sites in the
northeastern United States, respectively. Evans et al. (2005) demonstrated that Pb concentrations
in the litter layer (fresh litter + Oi horizon) sampled in a transect from Vermont to Quebec
decreased significantly between 1979 and 1996, reflecting a decrease in Pb deposition to forests
and upper soil horizons during that time period. Miller et al. (1993) and Wang and Benoit
(1997) used forest floor time-series data to model the response time (e folding time, the time it
takes a reservoir to decrease to the l/e, (ca. 37%) of its original amount) of Pb in the forest floor.
Miller et al. (1993) calculated O horizon response times of 17 years for the northern hardwood
forest and 77 years in the spruce-fir zone on Camel's Hump Mountain in Vermont. Wang and
Benoit (1997) determined that the O horizon would reach steady state with respect to Pb
n
(1.3 jig g Pb) by 2100. Both suggested that the vertical movement of organic particles
dominated Pb transport in the soil profile.
AX7.1.2.3 Inputs/Outputs of Atmospherically-delivered Lead in Terrestrial Ecosystems
The concentration of Pb in contemporary rainfall in the mid-Atlantic and northeastern
United States is on the order of 0.5 to 1 |ig/L (Wang et al., 1995; Kim et al., 2000; Scudlark
et al., 2005). Long-term trends in nine elemental concentrations (including Pb) in wet deposition
were measured on the Delmarva Peninsula near Lewes, Delaware, over the period from 1982 to
1989 (Figure AX7-1.2.1) (Scudlark et al., 1994). Of the nine elements measured, only Pb (and
possibly Al and Cd), indicated a decreasing trend over time (3 |ig/L in 1982 to <1.0 |ig/L in
1989). The authors attributed the dramatic decrease in Pb to the phasing out of Pb-alkyl
additives from gasoline as mandated in the 1972 Clean Air Act. For comparison, rainfall
measured in Los Angeles (CA) during 2003-2004 averaged 0.15 |ig/L, but showed nearly an
order-of-magnitude variation, presumably because of the arid environmental (Sabin et al., 2005).
See also Table 2-22 for additional rainfall information.
AX7-34
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1982 1983 1984 1985 1986
LEAD
1987
1988
1989
Figure AX7-1.2.1. Long-term (1982-1989) annual trends in lead concentrations (ug/L) in
Lewes, Delaware precipitation.
Source: Scudlarketal. (1994)
The role of dry deposition in the total deposition of Pb to terrestrial ecosystems is not
constrained well. Researchers have estimated that dry deposition accounts for anywhere
between 10 to >90% of total Pb deposition (Galloway et al., 1982; Wu et al., 1994; Sabin et al.,
2005). Migon et al. (1997) found total, wet, and dry Pb deposition to be 8.6, 1.6 and
7.0 |ig/m2/d, respectively, over the Ligurian Sea, France. Dry deposition velocities were
estimated at approximately 0.2 cm/sec, similar to anthropogenic element deposition velocities
measured at remote lakes around Lake Michigan (Yi et al., 2001). Yi et al. (2001) found that dry
deposition velocities for elements were correlated with particle concentrations in the following
order: coarse > total particle > fine particle. Refer to Table 2-21 for additional information on
dry, wet, and total Pb deposition velocities and fluxes.
Arid environments appear to have a much higher fraction of dry deposition: total
deposition (Sabin et al., 2005). Furthermore, it is possible that Clean Air Act Legislation enacted
in the late 1970s preferentially reduced Pb associated with fine particles, so the relative
AX7-35
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contributions of dry deposition may have changed in the last few decades. If the major source of
Pb to a terrestrial ecosystem is resuspended particulates from transportation corridors, then the
particle size fraction that dominates deposition may be relatively coarse (>50 jim) relative to
other atmospheric sources (Pirrone et al., 1995; Sansalone et al., 2003).
T^'7
Total contemporary loadings to terrestrial ecosystems are approximately 1 to 2 mg m
yearri (Wu et al., 1994; Wang et al., 1995; Simonetti et al., 2000; Sabin et al., 2005). This is a
relatively small annual flux of Pb if compared to the reservoir of approximately 0.5 to 4 g mr2 of
gasoline-derived Pb that is already in surface soils over much of the United States (Friedland
et al., 1992; Miller and Friedland, 1994; Erel and Patterson, 1994; Marsh and Siccama, 1997;
Yanai et al., 2004; Johnson et al., 2004; Evans et al., 2005). While vegetation can play an
important role in sequestering Pb from rain and dry deposition (Russell et al., 1981), direct
uptake of Pb from soils by plants appears to be low (Klaminder et al., 2005). High elevation
areas, particularly those near the base level of clouds often have higher burdens of atmospheric
contaminants (Siccama, 1974). A Pb deposition model by Miller and Friedland (1994) predicted
2.2 and 3.5 g Pb mr2 deposition for the 20th century in the deciduous zone (600 m) and the
coniferous zone (1000 m), respectively. More recently, Kaste et al. (2003) used radiogenic
isotope measurements on the same mountain to confirm higher loadings at higher elevation.
They measured 1.3 and 3.4 g gasoline-derived Pb mr2 in the deciduous zone and coniferous
zones, respectively. Higher atmospheric Pb loadings to higher elevations are attributed to
(1) the higher leaf area of coniferous species, which are generally more prevalent at high
elevation; (2) higher rainfall at higher elevation; and (3) increased cloudwater impaction at high
elevation (Miller et al., 1993).
Although inputs of Pb to ecosystems are currently low, Pb export from watersheds via
groundwater and streams is substantially lower than inputs. Therefore, even at current input
levels, watersheds are accumulating industrial Pb. However, burial/movement of lead over time
down into lower soil/sediment layers also tends to sequester it away from more biologically
active parts of the watershed (unless later disturbed or redistributed, e.g., by flooding, dredging,
etc.). Seeps and streams at the HBEF have Pb concentrations on the order of 10 to 30 pg Pb gri
(Wang et al., 1995). At a remote valley in the Sierra Nevada, Pb concentrations in streamwaters
n
were on the order of 15 pg Pb g (Erel and Patterson, 1994). Losses of Pb from soil horizons are
assumed to be via particulates (Dorr and Miinnich, 1989; Wang and Benoit, 1996, 1997). Tyler
AX7-36
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(1981) noted that Pb losses from a spruce forest A-horizon soil in Sweden were influenced by
season; with highest Pb fluxes being observed during warm, wet months. He suggested that
DOC production and Pb movement were tightly linked.
Surface soils across the United States are enriched in Pb relative to levels expected from
solely natural geogenic inputs (Friedland et al., 1984; Herrick and Friedland, 1990; Francek,
1992; Erel and Patterson, 1994; Marsh and Siccama, 1997; Yanai et al., 2004; Murray et al.,
2004). While some of this contaminant Pb is attributed to paint, salvage yards, shooting ranges,
and the use of Pb arsenate as a pesticide in localized areas (Francek, 1997), Pb contamination of
surface soils is essentially ubiquitous because of atmospheric pollution associated with metal
smelting and production, the combustion of fossil fuels, and waste incineration (Newhook et al.,
2003; Polissar et al., 2001). Surface soils in Michigan, for example, typically range from 8 to
several hundred ppm Pb (Francek, 1992; Murray et al., 2004). Soils collected and analyzed
beneath 50 cm in Michigan, however, range only from 4 to 60 ppm Pb (Murray et al., 2004).
In remote surface soils from the Sierra Nevada Mountains, litter and upper soil horizons are 20 to
40 ppm Pb, and approximately 75% of this Pb has been attributed to atmospheric deposition
during the 20th century (Erel and Patterson, 1994). Repeated sampling of the forest floor
(O horizon) in the northeastern United States demonstrates that the organic layer has retained
much of the Pb load deposited on ecosytems during the 20th century. Total Pb deposition during
the 20th century has been estimated at 1 to 3 g Pb mr2, depending on elevation and proximity to
urban areas (Miller and Friedland, 1994; Johnson et al., 1995a). Forest floors sampled during the
1980s and 1990s, and in early 2000 had between 0.7 and 2 g Pb mr2 (Friedland et al., 1992;
Miller and Friedland, 1994; Johnson et al., 1995a; Kaste et al., 2003; Yanai et al., 2004; Evans
et al., 2005). The pool of Pb in above- and below-ground biomass at the FfflEF is on the order of
0.13 g Pb mr2 (Johnson et al., 1995a).
The amount of Pb that has leached into mineral soil appears to be on the order of 20 to
50% of the total anthropogenic Pb deposition. Kaste et al. (2003) and Miller and Friedland
(1994) demonstrated that Pb loss from the forest floor at Camel's Hump Mountain in Vermont
depended on elevation. While the mineral soil in the deciduous forest had between 0.4 and 0.5 g
T^'7 T^'7
Pb m (out of 1 to 2 g Pb m in the total soil profile), at higher elevations the thicker coniferous
forest floor retained more than 90% of the total Pb deposition (Kaste et al., 2003). Johnson et al.
(1995a) determined that the forest floor at HBEF in the mid-1980s had about 0.75 g Pb mr2.
AX7-37
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Compared to their estimated 20th-century atmospheric Pb deposition of 0.9 g Pb mr2, the forest
floor has retained 83% of the atmospheric Pb loadings (Johnson et al., 1995a). Johnson et al.
(2004) noted that gasoline-derived Pb was a significant component of the labile Pb at the HBEF.
They calculated that Pb fluxes to the HBEF by atmospheric pollution were essentially equivalent
to the Pb released by mineral weathering over the past 12,000 years. Marsh and Siccama (1997)
used the relatively homogenous mineral soils underneath formerly plowed land in Rhode Island,
New Hampshire and Connecticut to assess the depth-distribution of atmospheric Pb. They
reported that 65% of the atmospheric Pb deposited during the 20th century is in the mineral soil
and 35% is in the forest floor. At their remote study site in the Sierra Nevada Mountains, Erel
and Patterson (1994) reported that most of the anthropogenic Pb was associated with the humus
fraction of the litter layer and soils sampled in the upper few cm.
Atmospherically delivered Pb is probably present in ecosystems in a variety of different
biogeochemical phases. A combination of Pb adsorbtion processes and the precipitation of Pb
minerals will typically keep dissolved Pb species low in soil solution, surface waters, and
streams (Sauve et al., 2000a; Jackson et al., 2005). While experimental and theoretical evidence
suggest that the precipitation of inorganic Pb phases and the adsorption of Pb on inorganic
phases can control the biogeochemistry of contaminant Pb (Nriagu, 1974; Ruby et al., 1994;
Jackson et al., 2005), the influence of organic matter on the biogeochemistry of Pb in terrestrial
ecosystems cannot be ignored in many systems. Organic matter can bind to Pb, preventing Pb
migration and the precipitation of inorganic phases (Manceau et al., 1996; Xia et al., 1997; Lang
and Kaupenjohann, 2003). As the abundance of organic matter declines in soil, Pb adsorption to
inorganic soil minerals and the direct precipitation of Pb phases may dominate the
biogeochemistry of Pb in terrestrial ecosystems (Ostergren et al., 2000a,b; Sauve et al., 2000a).
Conclusions
Advances in technology since the 1986 Lead AQCD have allowed for a quantitative
determination of the mobility, distribution, uptake, and fluxes of atmospherically delivered Pb in
ecosystems. Among other things, these studies have shown that industrial Pb represents a
significant fraction of total labile Pb in watersheds. Selective chemical extractions and
synchrotron-based X-ray studies have shown that industrial Pb can be strongly sequestered by
organic matter and by secondary minerals such as clays and oxides of Al, Fe, and Mn. Some of
AX7-38
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these studies have provided compelling evidence that the biomineralization of Pb phosphates by
soil organisms can play an important role in the biogeochemistry of Pb. Surface soils sampled
relatively recently demonstrate that the upper soil horizons (O + A horizons) are retaining most
of the industrial Pb burden introduced to the systems during the 20th century. The migration and
biological uptake of Pb in ecosystems is relatively low. The different biogeochemical behaviors
of Pb reported by various studies may be a result of the many different analytical techniques
employed, or they may be a result of natural variability in the behavior of Pb in different
systems.
Lead Uptake into Plants
Plants take up Pb via their foliage and through their root systems (U.S. Environmental
Protection Agency, 1986a; Pahlsson, 1989). Surface deposition of Pb onto plants may represent
a significant contribution to the total Pb in and on the plant, as has been observed for plants near
smelters and along roadsides (U.S. Environmental Protection Agency, 1986a). The importance
of atmospheric deposition on above-ground plant Pb uptake is well-documented (Dalenberg and
Van Driel, 1990; Jones and Johnston, 1991; Angel ova et al., 2004). Data examined from
experimental grassland plots in southeast England demonstrated that atmospheric Pb is a greater
contributor than soil-derived Pb in crop plants and grasses (Jones and Johnston, 1991). A study
by Dalenberg and Van Driel (1990) showed that 75 to 95% of the Pb found in field-grown test
plants (i.e., the leafy material of grass, spinach, and carrot; wheat grain; and straw) was from
atmospheric deposition. Angelova et al. (2004) found that tobacco grown in an industrial area
accumulated significant amounts of Pb from the atmosphere, although uptake from soil was also
observed. The concentration of Pb in tobacco seeds was linearly related to the concentration of
Pb in the exchangeable and carbonate-bound fractions of soil, as measured using sequential
extraction (Angelova et al., 2004). Lead in soil is more significant when considering uptake into
root vegetables (e.g., carrot, potato), since, as was noted in the 1986 Lead AQCD (U.S.
Environmental Protection Agency, 1986a), most Pb remains in the roots of plants.
There are two possible mechanisms (symplastic or apoplastic) by which Pb may enter the
root of a plant. The symplastic route is through the cell membranes of root hairs; this is the
mechanism of uptake for water and nutrients. The apoplastic route is an extracellular route
between epidermal cells into the intercellular spaces of the root cortex. Previously, Pb was
AX7-39
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thought to enter the plant via the symplastic route, probably by transport mechanisms similar to
those involved in the uptake of calcium or other divalent cations (i.e., transpirational mass flow,
diffusion, or active transport). However, it also had been speculated that Pb may enter the plant
via the apoplastic route (U.S. Environmental Protection Agency, 1986a). Sieghardt (1990)
determined that the mechanism of Pb uptake was via the symplastic route only and that the
apoplastic pathway of transport was stopped in the primary roots by the endodermis. He studied
the uptake of Pb into two plants, Minuartia verna (moss sandwort) and Silene vulgaris (bladder
campion) that colonize metal-contaminated sites. In the roots of both plants, Pb was found
mainly in the root cortex. Active ion uptake was required to transport the Pb into the stele and
then into the shoots of the plant (Sieghardt, 1990).
Although some plants translocate more Pb to the shoots than others, most Pb remains in
the roots of plants. Two mechanisms have been proposed to account for this relative lack of
translocation to the shoots: (1) Pb may be deposited within root cell wall material, or (2) Pb may
be sequestered within root cell organelles (U.S. Environmental Protection Agency, 1986a).
Pahlsson (1989) noted that plants can accumulate large quantities of Pb from the soil but that
translocation to shoots and leaves is limited by the binding of Pb ions at root surfaces and cell
walls. In a study by Wierzbicka (1999), 21 different plant species were exposed to Pb2+ in the
form of Pb-chloride. The plant species included cucumber (Cucumis sativus), soy bean (Soja
hispida), bean (Phaseolus vulgaris), rapeseed (Brassica napus), rye (Secale cereale), barley
(Hordeum vulgar e), wheat (Triticum vulgare\ radish (Raphanus sativus), pea (Pisum sativum),
maize (Zea mays), onion (Allium cepa), lupine (Lupinus luteus), bladder campion (Silene
vulgaris), Buckler mustard (Biscutella laevigata), and rough hawkbit (Leontodon hispidus).
Although, the amount of Pb taken up by the plant varied with species, over 90% of absorbed Pb
was retained in the roots. Only a small amount of Pb was translocated (~2 to 4%) to the shoots
of the plants. Lead in roots was present in the deeper layers of root tissues (in particular, the root
cortex) and not only on the root surface. There was no correlation between Pb tolerance
(measured as root mass increase expressed as a percentage of controls) and either root or shoot
tissue concentrations (Wierzbicka, 1999). The study by Wierzbicka (1999) was the first to report
that plants developing from bulbs, in this case the onion, were more tolerant to Pb than plants
developing from seeds. This tolerance was assumed to be related to the large amounts of Pb that
were transported from the roots and stored in the bulb of the plant (Wierzbicka, 1999).
AX7-40
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Uptake of Pb from soil into plants was modeled as part of Eco-SSL development (U.S.
Environmental Protection Agency, 2005a). The relationship derived between Pb in the soil and
Pb in a plant was taken from Bechtel Jacobs Company (BJC) (1998) and is as follows:
Ln(Cp) = 0.561 * Ln(Csoil) - 1.328 (AX7-1)
where Cp is the concentration of Pb in the plant (dry weight) and Csoil is the concentration of Pb
in the soil. This equation recognizes that the ratio of Pb concentration in plant to Pb
concentration in soil is not constant.
Invertebrates
There was no clear evidence suggesting a differential uptake of Pb into different species
of earthworm (Lumbricus terrestris, Aporrectodea rosea, and A. caliginosd) collected around a
smelter site near Avonmouth, England (Spurgeon and Hopkin, 1996a). This is in contrast to Pizl
and Josens (1995) and Terhivuo et al. (1994) who found Aporrectodea spp. accumulated more
Pb than Lumbricus. The authors suggested that these differences could be due to different
feeding behaviors, as Lumbricus feeds on organic material and Apporectodea species are
geophagus, ingesting large amounts of soil during feeding. The differences between species also
may be related to differing efficiencies in excretory mechanisms (Pizl and Josens, 1995).
However, the interpretation of species difference is complicated by a number of potentially
confounding variables, such as soil characteristics (e.g., calcium or other nutrient levels)
(Pizl and Josens, 1995).
The bioaccumulation of Pb from contaminated soil was tested using the earthworm
Eisemafetida, and the amount of Pb accumulated did not change significantly until the
concentration within soil reached 5000 mg/kg (Davies et al., 2003). This coincided with the
lowest soil concentrations at which earthworm mortality was observed. The ratio of the
concentration of Pb in worms to the concentration in soil decreased from 0.03 at 100 mg/kg to
0.001 at 3000 mg/kg, but then increased quickly to 0.02 at 5000 mg/kg. The authors concluded
that earthworms exhibit regulated uptake of Pb at levels of low contamination (<3000 mg/kg)
until a critical concentration is reached, at which point this mechanism breaks down, resulting in
unregulated accumulation and mortality. This study was conducted using test methods where
AX7-41
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soil was not allowed to equilibrate following the addition of Pb and prior to the addition of the
test organisms. This may have resulted in an increased bioavailability and overestimated Pb
toxicity relative to actual environmental conditions (Davies et al., 2003). See the discussion in
Section AX7.1.2 on the effects of aging on Pb sorption processes.
Lock and Janssen (2002) and Bongers et al. (2004) found that Pb-nitrate was more toxic
than Pb-chloride to survival and reproduction of the springtail Folsomia Candida. However,
percolation (removal of the chloride or nitrate counted on) caused a significant decrease in Pb-
nitrate toxicity such that there was no difference in toxicity once the counterion was removed
(Bongers et al., 2004). No change in toxicity was observed for Pb-chloride once the chloride
was removed from the soil. Bongers et al. (2004) suggested that the nitrate ion was more toxic
than the chloride ion to springtails.
Uptake of Pb from soil into earthworms was also modeled as part of Eco-SSL
development (U.S. Environmental Protection Agency, 2005a). The relationship derived between
Pb in the soil and Pb in an earthworm was taken from Sample et al. (1999) and is as follows:
Ln(Cworm) = 0.807 * Ln(Csoil) - 0.218 (AX7-2)
where Cworm is the concentration of Pb in the earthworm (dry weight) and Csoil is the
concentration of Pb in the soil. This equation recognizes that the ratio of Pb concentration in
worm to Pb concentration in soil is not constant.
Wildlife
Research has been conducted to determine what Pb concentrations in various organs
would be indicative of various levels of effects. For example, Franson (1996) compiled data to
determine what residue levels were consistent with three levels of effects in Falconiformes (e.g.,
falcons, hawks, eagles, kestrels, ospreys), Columbiformes (e.g., doves, pigeons), and Galliformes
(e.g., turkey, pheasant, partridge, quail, chickens). The three levels of effect were (1) subclinical,
which are physiological effects only, such as the inhibition of 5-aminolevulinic acid dehydratase
(ALAD; see Section AX7.1.3.3); (2) toxic, a threshold level marking the initiation of clinical
signs, such as anemia, lesions in tissues, weight loss, muscular incoordination, green diarrhea,
and anorexia; and (3) compatible with death, an approximate threshold value associated with
AX7-42
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death in field, captive, and/or experimental cases of Pb poisoning. The tissue Pb levels
associated with these levels of effects are presented in Table AX7-1.2.1.
Table AX7-1.2.1. Tissue Lead Levels in Birds Causing Effects
(taken from Franson, 1996)
Blood
Order (^g/dL)
Falconiformes
Subclinical 0.2-1.5
Toxic >1
Compatible with death >5
Columbi 'formes
Subclinical 0.2-2.5
Toxic >2
Compatible with death >10
Galliformes
Subclinical 0.2-3
Toxic >5
Compatible with death >10
Liver
(ppm wet wt.)
2-4
>3
>5
2-6
>6
>20
2-6
>6
>15
Kidney
(ppm wet wt.)
2-5
>3
>5
2-20
>15
>40
2-20
>15
>50
Tissue residue levels below the Subclinical levels in Table AX7-1.2.1 should be
considered "background" (Franson, 1996). Levels in the Subclinical range are indicative of
potential injury from which the bird would probably recover if Pb exposure was terminated.
Toxic residues could lead to death. Residues above the compatible-with-death threshold are
consistent with Pb-poisoning mortality (Franson, 1996). Additional information on residue
levels for Passeriformes (e.g., sparrows, starlings, robins, cowbirds), Charadriiformes (e.g., gulls,
terns), Gruiformes (e.g., cranes), Ciconiformes (e.g., egrets), Gaviformes (e.g., loons), and
Strigiformes (e.g., owls) is available in Franson (1996). Scheuhammer (1989) found blood Pb
concentrations of between 0.18 and 0.65 |ig/mL in mallards corresponded to conditions
associated with greater than normal exposure to Pb but that should not be considered Pb
poisoning.
AX7-43
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Lead concentrations in various tissues of mammals also have been correlated with toxicity
(Ma, 1996). The tissues commonly analysed for Pb are blood, liver, and kidney. Typical
baseline levels of blood Pb are approximately 4 to 8 |ig/dL for small mammals, and 2 to 6 |ig/dL
for mature cattle. Typical baseline levels of Pb in liver are 1 to 2 mg/kg dw for small mammals.
Typical baseline levels of Pb in kidney are 0.2 to 1.5 mg/kg dw for mice and voles, but shrews
typically have higher baseline levels of 3 to 19 mg/kg dw. Ma (1996) concluded that Pb levels
less than 5 mg/kg dw in liver and 10 mg/kg dw in kidney were not associated with toxicity, but
that levels greater than 5 mg/kg dw in liver and greater than 15 mg/kg dw in kidney could be
taken as a chemical biomarker of toxic exposure to Pb in mammals. Humphreys (1991) noted
that the concentrations of Pb in liver and kidney can be elevated in animals with normal blood Pb
concentrations (and without exhibiting clinical signs of Pb toxicity), because Pb persists in these
organs longer than in blood.
Uptake of Pb from soil into small mammals was also modeled as part of Eco-SSL
development (U.S. Environmental Protection Agency, 2005a). The relationship derived between
Pb in the soil and Pb in the whole-body of a small mammal was taken from Sample et al. (1998)
and is as follows:
Ln(Cmammal) = 0.4422 * Ln(Csoil) + 0.0761 (AX7-3)
Where Cmammal is the concentration of Pb in small mammals (dry weight) and Csoil is the
concentration of Pb in the soil. Similar to the uptake equations for plants (Eq. 8-1) and
earthworms (Eq 8-2), the equation for mammalian uptake recognizes that the ratio of Pb
concentration in small mammals to Pb concentration in soil is not constant.
AX7.1.2.4 Resistance Mechanisms
Many mechanisms related to heavy metal tolerance in plants and invertebrates have been
described, including avoidance (i.e., root redistribution, food rejection), exclusion (i.e., selective
uptake and translocation), immobilization at the plant cell wall, and excretion (i.e., foliar
leakage, moulting) (Tyler et al., 1989; Patra et al., 2004). The following section reviews the
recent literature on the resistance mechanisms of plants and invertebrates through mitigation of
Pb (1) toxicity or (2) exposure.
AX7-44
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Detoxification Mechanisms
Lead sequestration in cell walls may be the most important detoxification mechanism in
plants. Calcium may play a role in this detoxification by regulating internal Pb concentrations
through the formation of Pb-containing precipitates in the cell wall (Antosiewicz, 2005). Yang
et al. (2000) screened 229 varieties of rice (Oryza saliva) for tolerance or sensitivity to Pb and
found that the oxalate content in the root and root exudates was increased in Pb-tolerant varieties.
The authors suggested that the oxalate reduced Pb bioavailability, and that this was an important
tolerance mechanism (Yang et al., 2000). Sharma et al. (2004) found Pb-sulfur and Pb-sulfate in
the leaves, and Pb-sulfur in the roots of Sesbania drummondii (Rattlebox Drummond), a Pb
hyperaccumulator plant grown in Pb-nitrate solution. They hypothesized that these sulfur
ligands were indicative of glutathione and phytochelatins, which play a role in heavy metal
homeostasis and detoxification (Sharma et al., 2004).
Sea pinks (Armeria maritimd) grown on a metal-contaminated site (calamine spoils more
than 100 years old) accumulated 6H the concentrations of Pb in brown (dead and withering)
leaves than green leaves (Szarek-Lukaszewska et al., 2004). The concentration of Pb in brown
leaves was similar to that in roots. This greater accumulation of Pb into older leaves was not
observed in plants grown hydroponically in the laboratory. The authors hypothesized that this
sequestering of Pb into the oldest leaves was a detoxification mechanism (Szarek-Lukaszewska
et al., 2004).
Terrestrial invertebrates also mitigate Pb toxicity. Wilczek et al. (2004) studied two
species of spider, the web-building Agelena labyrinthica, and the active hunter wolf spider
Pardosa lugubris. The activity of metal detoxifying enzymes (via the glutathione metabolism
pathways) was greater in A labyrinthica and in females of both species (Wilczek et al., 2004).
Marinussen et al. (1997) found that earthworms can excrete 60% of accumulated Pb very
quickly once exposure to Pb-contaminated soils has ended. However, the remainder of the body
burden is not excreted, possibly due to the storage of Pb in waste nodules that are too large to be
excreted (Hopkin, 1989). Gintenreiter et al. (1993) found that Lepidoptera larvae (in this case,
the gypsy moth Lymantria dispaf) eliminated Pb, to some extent, in the meconium (the fluid
excreted shortly after emergence from the chrysalis).
Lead, in the form of pyromorphite (Pbs^O^Cl), was localized in the anterior pharynx
region of the nematode Ceanorhabditis elegans (Jackson et al., 2005). The authors hypothesized
AX7-45
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that the nematode may detoxify Pb via its precipitation into pyromorphite, which is relatively
insoluble (Jackson et al., 2005).
Avoidance Response
Studies with soil invertebrates hypothesize that these organisms may avoid soil with high
Pb concentrations. For example, Bengtsson et al. (1986) suggested that the lower Pb
concentrations in earthworm tissues may be a result of lowered feeding activity of worms at
higher Pb concentrations in soil.
AX7.1.2.5 Physiological Effects of Lead
Several studies have measured decreased blood ALAD activity in birds and mammals
exposed to Pb (U.S. Environmental Protection Agency, 1986a). Recent studies on the
physiological effects of Pb to consumers have focused on heme synthesis (as measured by
ALAD activity and protoporphyrin concentration), lipid peroxidation, and production of fatty
acids. Effects on growth are covered in Section AX7.1.4.
Biochemically, Pb adversely affects hemoglobin synthesis in birds and mammals. Early
indicators of Pb exposure in birds and mammals include decreased blood ALAD concentrations
and increased protoporphyrin IX activity. The effects of Pb on blood parameters and the use of
these parameters as sensitive biomarkers of exposure has been well documented (Eisler, 1988;
U.S. Environmental Protection Agency, 2005b). However, the linkage between these
biochemical indicators and ecologically relevant effects is less well understood. Low-level
inhibition of ALAD is not generally considered a toxic response, because this enzyme is thought
to be present in excess concentrations; rather, it may simply indicate that the organism has
recently been exposed to Pb (Henny et al., 1991).
Schlick et al. (1983) studied ALAD inhibition in mouse bone marrow and erythrocytes.
They estimated that an absorbed dose of between 50 and 100 jig Pb-acetate/kg body weight per
day would result in long-term inhibition of ALAD.
Beyer et al. (2000) related blood Pb to sublethal effects in waterfowl along the
Coeur d=Alene River near a mining site in Idaho. The sublethal effects measured included,
among others, red blood cell ALAD activity and protoporphyrin levels in the blood. As found in
other studies, ALAD activity was the most sensitive indicator of Pb exposure, decreasing to 3%
AX7-46
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of the reference value at a blood Pb concentration of 0.68 mg/kg ww (wet weight).
Protoporphyrin concentrations showed a 4.2-fold increase at this same concentration.
Henny et al. (1991) studied osprey along the Coeur d=Alene River. There were no
observations of death, behavioral abnormalities, or reduced productivity related to Pb exposure,
although inhibition of blood ALAD and increased protoporphyrin concentrations were measured
in ospreys. Henny et al. (1991) hypothesized that no impacts to osprey were observed, even
though swan mortality was documented in the area because swans feed at a lower trophic level
(i.e., Pb does not biomagnify, and thus is found at higher concentrations in lower trophic level
organisms).
Hoffman et al. (2000a) also studied the effects of Coeur d'Alene River sediment on
waterfowl, focusing on mallard ducklings for 6 weeks after hatching. The study revealed that a
90% reduction in ALAD activity and a greater than 3-fold increase in protoporphyrin
concentration occurred when blood Pb reached a concentration of 1.41 mg/kg ww as a result of
the ducklings being fed a diet composed of 12% sediment (3449 mg/kg Pb). Those ducklings
fed a diet composed of 24% sediment were found to have a mean blood Pb concentration of
2.56 mg/kg ww and a greater than 6-fold increase in protoporphyrin concentration. Hoffman
et al. (2000b) also studied Canada Geese (Branta canadensis) goslings in a similar fashion.
The results revealed that, while blood Pb concentrations in goslings were approximately half
(0.68 mg/kg ww) of those found in ducklings under the same conditions (12% diet of
3449 mg/kg sediment Pb), goslings showed an increased sensitivity to Pb exposure. Goslings
experienced a 90% reduction in ALAD activity and a 4-fold increase in protoporphyrin
concentration, similar to conditions found in the ducklings, although blood Pb concentrations
were half those found in the ducklings. More serious effects were seen in the goslings when
blood Pb reached 2.52 mg/kg, including decreased growth and mortality.
Redig et al. (1991) reported a hawk LOAEL (lowest observed adverse effect level) of
0.82 mg/kg-day for effects on heme biosynthetic pathways. Lead dosages as high as 1.64 to
6.55 mg/kg-day caused neither mortality nor clinical signs of toxicity. A dose of 6.55 mg/kg-day
resulted in blood Pb levels of 1.58 |ig/mL. There were minimal changes in immune function
(Redig etal., 1991).
Repeated oral administration of Pb resulted in biochemical alterations in broiler chickens
(Brar et al., 1997a,b). At a dose of 200 mg/kg-day Pb-acetate, there were significant increases in
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plasma levels of uric acid and creatinine and significant declines in the levels of total proteins,
albumin, glucose, and cholesterol. Brar et al. (1997a) suggested that increased uric acid and
creatinine levels could be due to an accelerated rate of protein catabolism and/or kidney damage.
They also suggested that the decline in plasma proteins and albumin levels may be caused by
diarrhea and liver dysfunction due to the Pb exposure. Brar et al. (1997b) also found that
significant changes in plasma enzymes may be causing damage to other organs.
Lead can cause an increase in tissue lipid peroxides and changes in glutathione
concentrations, which may be related to peroxidative damage of cell membranes (Mateo and
Hoffman, 2001). There are species-specific differences in resistance to oxidative stress (lipid
peroxidation), which may explain why Canada geese are more sensitive to Pb poisoning than
mallards (Mateo and Hoffman, 2001). Lead also caused an increase in the production of the fatty
acid arachidonic acid, which has been associated with changes in bone formation and immune
response (Mateo et al., 2003a). The effects observed by Mateo et al. (2003a,b) were associated
with very high concentrations of Pb in the diet (1840 mg Pb/kg diet), much higher than would be
found generally in the environment, and high enough that birds decreased their food intake.
Lead also induces lipid peroxidation in plants. Rice plants exposed to a highly toxic level
of Pb (1000 jiM in nutrient solution) showed elevated levels of lipid peroxides, increased activity
of superoxide dismutase, guaiacol peroxidase, ascorbate peroxidase, and glutatione reductase
(Verma and Dubey, 2003). The elevated levels of these enzymes suggest the plants may have an
antioxidative defense mechanism against oxidative injury caused by Pb (Verma and Dubey,
2003).
AX7.1.2.6 Factors that Modify Organism Response
Research has demonstrated that Pb may affect survival, reproduction, growth,
metabolism, and development in a wide range of species. These effects may be modified by
chemical, biological, and physical factors. The factors that modify responses of organisms to Pb
are described in the following sections.
Genetics
Uptake and toxicity of Pb to plants are influenced strongly by the type of plant. Liu et al.
(2003) found that Pb uptake and translocation by rice plants differed by cultivar (a cultivated
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variety of plant produced by selective breeding) but was not related to genotype. Twenty
cultivars were tested from three genotypes. The differences in Pb concentrations among
cultivars were smallest when comparing concentrations in the grains at the ripening stage.
This study also found that toxicity varied by cultivar; at 800 mg Pb/kg soil, some cultivars
were greatly inhibited, some were significantly improved, and others showed no change.
Dearth et al. (2004) compared the response of Fisher 344 (F344) rats and Sprague-Dawley
(SD) rats to exposure via gavage to 12 mg Pb/mL as Pb-acetate. Blood Pb levels in the F344
dams were higher than those of the SD dams. Lead delayed the timing of puberty and
suppressed hormone levels in F344 offspring. These effects were not observed in the offspring
of SD rats, even when the dose was doubled. The authors conclude that F344 rats are more
sensitive to Pb (Dearth et al., 2004).
Biological Factors
Several biological factors may influence Pb uptake and organism response, including
organism age, sex, species, feeding guild, and, for plants, the presence of mycorrhizal fungi.
Monogastric animals are more sensitive to Pb than ruminants (Humphreys, 1991).
Younger organisms may be more susceptible to Pb toxicity (Eisler, 1988; Humphreys,
1991). Nestlings are more sensitive to the effects of Pb than older birds, and young altricial birds
(species unable to self-regulate body heat at birth, such as songbirds), are considered more
sensitive than precocial birds (species that have a high degree of independence at birth, such as
quail, ducks, and poultry) (Scheuhammer, 1991).
Gender can also have an effect on the accumulation of Pb by wildlife (Eisler, 1988).
Female birds accumulate more Pb than males (Scheuhammer, 1987; Tejedor and Gonzalez,
1992). These and other authors have related this to the increased requirement for calcium in
laying females.
Different types of invertebrates accumulate different amounts of Pb from the environment
(U.S. Environmental Protection Agency, 1986a). There may be species- and sex-specific
differences in accumulation of Pb into invertebrates, specifically arthropods. This has been
shown by Wilczek et al. (2004) who studied two species of spider, the web-building
A. labyrinthica and the active hunter wolf spider P. lugubris. The body burdens of Pb in the
wolf spider were higher than in the web-building spider, and this may be due to the more
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effective use of glutathione metabolism pathways in A. labyrinthica. Body burdens of females
were lower than those of males in both species. This was also observed in spiders by Rabitsch
(1995a). Females are thought to be able to detoxify and excrete excess metals more effectively
than males (Wilczek et al., 2004). Lead accumulation has been measured in numerous species of
arthropods with different feeding strategies. Differences were observed between species
(Janssen and Hogervorst, 1993; Rabitsch, 1995a) and depending upon sex (Rabitsch, 1995a),
developmental stage (Gintenreiter et al., 1993; Rabitsch, 1995a), and season (Rabitsch, 1995a).
Uptake of Pb may be enhanced by symbiotic associations between plant roots and
mycorrhizal fungi. Similar to the mechanism associated with increased uptake of nutrients,
mycorrhizal fungi also may cause an increase in the uptake of Pb by increasing the surface area
of the roots, the ability of the root to absorb particular ions, and the transfer of ions through the
soil (U.S. Environmental Protection Agency, 1986a). There have been contradictory results
published in the literature regarding the influence of mycorrhizal organisms on the uptake and
toxicity of Pb to plants (see review in Pahlsson, 1989). Lin et al. (2004) found that the
bioavailability of Pb increased in the rhizosphere of rice plants, although the availability varied
with Pb concentration in soil. Bioavailability was measured as the soluble plus exchangeable Pb
fraction from sequential extraction analysis. The authors hypothesized that the enhanced
solubility of Pb may be due to a reduced pH in the rhizosphere or, more likely, the greater
availability of organic ligands, which further stimulates microbial growth (Lin et al., 2004).
Increased bioavailability of Pb in soil may increase the uptake of Pb into plants, although
this was not assessed by Lin et al. (2004). However, Dixon (1988) found that red oak
(Quercus rubrd) seedlings with abundant ectomycorrhizae had lower Pb concentrations in their
roots than those seedlings without this fungus, although only at the 100 mg Pb/kg sandy loam
soil concentration (no differences were found at lower Pb concentrations). Lead in soil also was
found to be toxic to the ectomycorrhizal fungi after 16 weeks of exposure to 50 mg Pb/kg or
more (Dixon, 1988). Malcova and Gryndler (2003) showed that maize root exudates from
mycorrhizal fungi can ameliorate heavy metal toxicity until a threshold metal concentration was
surpassed. This may explain the conflicting results in the past regarding the uptake and toxicity
of Pb to plants with mycorrhizal fungi.
The type of food eaten is a major determinant of Pb body burdens in small mammals, with
insectivorous animals accumulating more Pb than herbivores or granivores (U.S. Environmental
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Protection Agency, 1986a). In fact, the main issue identified by the EPA (U.S. Environmental
Protection Agency, 1986a) related to invertebrate uptake of Pb was not toxicity to the
invertebrates, but accumulation of Pb to levels that may be toxic to their consumers. Several
authors suggest that shrews are a good indicator of metal contamination, because they tend to
accumulate higher levels of metals than herbivorous small mammals (see data summary in
Sample et al. (1998)). Shrews accumulate higher levels of metals in contaminated habitats,
because their diet mainly consists of detritivores (i.e., earthworms) and other soil invertebrates in
direct contact with the soil (Beyer et al., 1985).
Physical/Environmental Factors
Plants
The uptake and distribution of Pb into higher plants from the soil is affected by various
chemical and physical factors including the chemical form of Pb, the presence of other metal
ions, soil type, soil pH, cation exchange capacity (CEC), the amount of Fe/Mn-oxide films
present, organic matter content, temperature, light, and nutrient availability. A small fraction of
Pb in soil may be released into the soil water, which is then available to be taken up by plants
(U.S. Environmental Protection Agency, 1986a).
The form of Pb has an influence on its toxicity to plants. For example, Pb-oxide is less
toxic than more bioavailable forms such as Pb-chloride or Pb-acetate. In a study by Khan and
Frankland (1983), radish plants were exposed to Pb-oxide and Pb-chloride in a loamy sand at pH
5.4, in a 42-day study. In a tested concentration range of 0 to 5000 mg/kg, root growth was
inhibited by 24% at 500 mg/kg for Pb-chloride and an ECso of 2400 mg/kg was calculated from a
dose-response curve. Plant growth ceased at 5000 mg/kg and shoots exhibited an EC50 of
2800 mg/kg. For Pb-oxide exposure (concentration range of 0 to 10,000 mg/kg), reported results
indicate an ECso of 12,000 mg/kg for shoot growth and an ECso of 10,000 mg/kg for root growth.
There was no effect on root growth at 500 mg/kg and a 26% reduction at 1000 mg/kg Pb oxide.
Soil pH is the most influential soil property with respect to uptake and accumulation of Pb
into plant species. This is most likely due to increased bioavailability of Pb created by low soil
pH. At low soil pH conditions, markedly elevated Pb toxicity was reported for red spruce
(P. rubens) (Seller and Paganelli, 1987). At a soil pH of 4.5, ryegrass (Lolium hybridum)
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and oats (Avena sativd) had significantly higher Pb concentrations after 3 months of growth
compared to plants grown at pH 6.4 (Allinson and Dzialo, 1981).
In vertebrates
The uptake of Pb into invertebrates depends on the physical environment and parameters
such as pH, calcium concentration, organic matter content, and CEC. Greater accumulation is
found generally when the soil pH or organic content is lower (U.S. Environmental Protection
Agency, 1986a).
Soil pH has a significant influence on uptake of Pb into invertebrates. Peramaki et al.
(1992) studied the influence of soil pH on uptake into the earthworm Aporrectodea caliginosa.
Lead accumulation was lowest at the highest pH values, but there was no statistical difference
due to variability in the data. Variability in the response also was found by Bengtsson et al.
(1986), who reared earthworms (Dendrobaena rubidd) in acidified soils at pH 4.5, 5.5, or 6.5.
Lead uptake into worms was pH-dependent, although the highest concentrations were not always
found at the lowest pH. There was no clear relationship between Pb concentration in cocoons
and soil pH, and Pb concentrations were higher in the hatchlings than in the cocoons. As has
been reported in many other studies (Neuhauser et al., 1995), concentration factors (ratio of Pb in
worm to Pb in soil) were lower at higher Pb concentrations in soil. The authors attribute some of
this to a lowered feeding activity in worms at higher Pb concentrations (Bengtsson et al., 1986).
Beyer et al. (1987) and Morgan and Morgan (1988) recognized that other factors beyond
soil pH could influence the uptake of Pb into earthworms, which may be the cause of the
inconsistencies reported by several authors. Both studies evaluated worm uptake of Pb relative
to pH, soil calcium concentration, and organic matter content. Morgan and Morgan (1988) also
considered CEC, and Beyer et al. (1987) considered concentrations of phosphorus, potassium, or
magnesium in soil. Both studies found that calcium concentrations in soil were correlated with
soil pH. Morgan and Morgan (1988) also found that CEC was correlated with percentage
organic matter. Soil pH (coupled with CEC) and soil calcium were found to play significant
roles in the uptake of Pb into worms (Beyer et al., 1987; Morgan and Morgan, 1988). Beyer
et al. (1987) noted that concentrations of phosphorus in soil had no effect.
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Nutritional Factors
Diet is a significant modifier of Pb absorption and of toxic effects in many species of
birds and mammals (Eisler, 1988). Dietary deficiencies in calcium, zinc, iron, vitamin E, copper,
thiamin, phosphorus, magnesium, fat, protein, minerals, and ascorbic acid increased Pb
absorption and its toxic effects (Eisler, 1988).
Mateo et al. (2003b) studied intraspecies sensitivity to Pb-induced oxidative stress, by
varying the vitamin E content of mallard diets. Vitamin E can protect against peroxidative
damage and was found to decrease the lipid peroxidation in nerves of birds; however, it did not
alleviate any sign of the Pb poisoning. The authors hypothesize that inhibition of antioxidant
enzymes and interaction with sulfhydryl groups of proteins may have a greater influence on Pb
toxicity than lipid peroxidation (Mateo et al., 2003b). The effects observed by Mateo et al.
(2003b) were associated with very high concentrations of Pb in diet (1840 mg Pb/kg diet), much
higher than would be found generally in the environment, and high enough that the birds
decreased their food intake.
Mallard ducklings were exposed to Pb-contaminated sediment and either a low nutrition
or optimal nutrition diet (Douglas-Stroebel et al., 2005). Lead exposure combined with a
nutritionally inferior diet caused more changes in behavior (as measured by time bathing, resting,
and feeding) than Pb exposure or low-nutrition diet alone. These effects may be due to the low-
nutrition diet being deficient in levels of protein, amino acids, calcium, zinc, and other nutrients.
Zebra finches (Taeniopygia guttatd) were exposed to Pb-acetate via drinking water at
20 mg/L for 38 days, along with either a low- or high-calcium diet (Snoeijs et al., 2005). Lead
uptake into tissues was enhanced by a low-calcium diet. Lead did not affect body weight,
hematocrit, or adrenal stress response. Lead suppressed the humoral immune response only in
females on a low-calcium diet, suggesting increased susceptibility of females to Pb (Snoeijs
et al., 2005).
Interactions with Other Pollutants
Lead can interact with other pollutants to exert toxicity in an antagonistic (less than
additive), independent, additive, or synergistic (more than additive) manner. Concurrent
exposure to Pb and additional pollutant(s) can affect the ability of plants to uptake Pb or the
other pollutant. However, the uptake and toxic response of plants exposed to Pb combined with
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other metals is inconsistent (Pahlsson, 1989). Therefore, no generalizations can be made about
the relative toxicity of metal mixtures. For example, An et al. (2004) conducted acute, 5-day
bioassays on cucumber exposed to Pb, Pb + copper, Pb + cadmium, or Pb + copper + cadmium
in a sandy loam soil of pH 4.3. Shoot and root growth were measured. Depending on the tissue
and metal combination, additivity, synergism, or antagonism was observed in the responses to
these metals. In fact, the response in roots was not consistent with the response in shoots for the
binary mixtures. However, the combined effects were greater in the roots than the shoots, which
may be explained by the tendency for Pb and other heavy metals to be retained in the roots of
plants. In addition, the pattern of metal bioaccumulation into plant tissue did not always
correlate with the toxic response. However, antagonism was observed in the response of roots
and shoots exposed to all three metals, and this was reflected in the decreased accumulation of
metals into plant tissues. The authors hypothesized that this may be due to the formation of less
bioavailable metal complexes (An et al., 2004).
He et al. (2004) found that selenium and zinc both inhibited the uptake of Pb into Chinese
cabbage (Brassica rapct) and lettuce (Lactuca saliva). Zinc applied at 100 mg/kg or selenium
applied at 1 mg/kg decreased the uptake of Pb (present in soil at 10 mg/kg as Pb-nitrate) into
lettuce by 15% and 20%, respectively, and into Chinese cabbage by 23 and 20%, respectively.
Selenium compounds were evaluated to determine whether they could change the
inhibition of ALAD in liver, kidney, or brain of mice exposed to Pb-acetate (Perottoni et al.,
2005). Selenium did not affect the inhibition of ALAD in the kidney or liver, but it did reverse
the ALAD inhibition in mouse brain.
Co-occurrence of cadmium with Pb resulted in reduced blood Pb concentrations in rats
(Garcia and Corredor, 2004). The authors hypothesized that cadmium may block or antagonize
the intestinal absorption of Pb, or the metallothionein induced by cadmium may sequester Pb.
However, this was not observed in pigs, where blood Pb concentrations were greater when
cadmium was also administered (Phillips et al., 2003). The effect on growth rate also was
additive when both metals were given to young pigs (Phillips et al., 2003).
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AX7.1.2.7 Summary
The current document expands upon and updates knowledge related to the uptake,
detoxification, physiological effects, and modifying factors of Pb toxicity to terrestrial
organisms.
Surface Deposition onto Plants
Recent work (Dalenberg and Van Driel, 1990; Jones and Johnston, 1991; Angelova et al.,
2004) has supported previous results and conclusions that surface deposition of Pb onto above-
ground vegetation from airborne sources may be significant (U.S. Environmental Protection
Agency, 1986a). Similarly, it has been well documented previously that Pb in soil also is taken
up by plants, although most remains in the roots, there is little translocation to shoots, leaves, or
other plant parts (U.S. Environmental Protection Agency, 1986a). More recent work continues
to support this finding (Sieghardt, 1990), and one study found increased tolerance in species with
bulbs, possibly due to the storage of Pb in the bulb (Wierzbicka, 1999).
Uptake Mechanism into Plants
Lead was thought previously to be taken up by plants via the symplastic route (through
cell membranes), although it was unknown whether some Pb also may be taken up via the
apoplastic route (between cells) (U.S. Environmental Protection Agency, 1986a). Recent work
has shown that the apoplastic route of transport is stopped in the primary roots by the endodermis
(Sieghardt, 1990), supporting the previous conclusion that the symplastic route is the most
significant route of transport into plant cells.
Species Differences in Uptake into Earthworms
Different species of earthworm accumulated different amounts of Pb, and this was not
related to feeding strategy (U.S. Environmental Protection Agency, 1986a). This is supported by
recent work, which has shown Aporrectodea accumulated more than Lumbricus (Terhivuo et al.,
1994; Pizl and Josens, 1995), although this is not consistently observed (Spurgeon and Hopkin,
1996a).
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Speciation and Form of Lead
Recent work supports previous conclusions that the form of metal tested, and its
speciation in soil, influence uptake and toxicity to plants and invertebrates (U.S. Environmental
Protection Agency, 1986a). The oxide form is less toxic that the chloride or acetate forms,
which are less toxic than the nitrate form of Pb (Khan and Frankland, 1983; Lock and Janssen,
2002; Bongers et al., 2004). However, these results must be interpreted with caution, as the
counterion (e.g., the nitrate ion) may be contributing to the observed toxicity (Bongers et al.,
2004).
Detoxification in Plants
Lead may be deposited in root cell walls as a detoxification mechanism (U.S.
Environmental Protection Agency, 1986a), and this may be influenced by calcium concentrations
(Antosiewicz, 2005). Yang et al. (2000) suggested that the oxalate content in root and root
exudates reduced the bioavailability of Pb in soil, and that this was an important tolerance
mechanism. Other hypotheses put forward recently include the presence of sulfur ligands
(Sharma et al., 2004) and the sequestration of Pb in old leaves (Szarek-Lukaszewska et al., 2004)
as detoxification mechanisms.
Detoxification in Invertebrates
Lead detoxification has not been studied extensively in invertebrates. Glutathione
detoxification enzymes were measured in two species of spider (Wilczek et al., 2004). Lead may
be stored in waste nodules in earthworms (Hopkin, 1989) or as pyromorphite in the nematode
(Jackson et al., 2005).
Physiological Effects
The effects on heme synthesis (as measured by ALAD activity and protoporphyrin
concentration, primarily) have been well-documented (U.S. Environmental Protection Agency,
1986a) and continue to be studied (Schlick et al., 1983; Scheuhammer, 1989; Henny et al., 1991;
Redig et al., 1991; Beyer et al., 2000; Hoffman et al., 2000a,b). However, Henny et al. (1991)
caution that changes in ALAD and other enzyme parameters are not always related to adverse
effects, but simply indicate exposure. Other effects on plasma enzymes, which may damage
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other organs, have been reported (Brar et al., 1997a,b). Lead also may cause lipid peroxidation
(Mateo and Hoffman, 2001), which may be alleviated by vitamin E, although Pb poisoning may
still result (Mateo et al., 2003b). Changes in fatty acid production have been reported, which
may influence immune response and bone formation (Mateo et al., 2003a).
Response Modification
Genetics, biological factors, physical/environmental factors, nutritional factors, and other
pollutants can modify terrestrial organism response to Pb. Fisher 344 rats were found to be more
sensitive to Pb than Sprague-Dawley rats (Dearth et al., 2004). Younger animals are more
sensitive than older animals (Eisler, 1988; Scheuhammer, 1991), and females generally are more
sensitive than males (Scheuhammer, 1987; Tejedor and Gonzalez, 1992; Snoeijs et al., 2005).
Monogastric animals are more sensitive than ruminants (Humphreys, 1991). Insectivorous
mammals may be more exposed to Pb than herbivores (Beyer et al., 1985; Sample et al., 1998),
and higher tropic-level consumers may be less exposed than lower trophic-level organisms
(Henny et al., 1991). Diets deficient in nutrients (including calcium) result in increased uptake
of Pb (Snoeijs et al., 2005) and greater toxicity (Douglas-Stroebel et al., 2005) in birds, relative
to diets containing adequate nutrient levels.
Mycorrhizal fungi may ameliorate Pb toxicity until a threshold is surpassed (Malcova and
Gryndler, 2003), which may explain why some studies show increased uptake into plants (Lin
et al., 2004) while others show no difference or less uptake (Dixon, 1988). Uptake of Pb into
plants and soil invertebrates increases with a decrease in soil pH. However, calcium content,
organic matter content, and cation exchange capacity of soils also have had a significant
influence on uptake of Pb into plants and invertebrates (Beyer et al., 1987; Morgan and Morgan,
1988).
Interactions of Pb with other metals are inconsistent, depending on the endpoint
measured, the tissue analyzed, the animal species, and the metal combination (Phillips et al.,
2003; An et al., 2004; He et al., 2004; Garcia and Corredor, 2004; Perottoni et al., 2005).
AX7.1.3 Exposure-Response of Terrestrial Species
Section AX7.1.3 summarized the most important factors related to uptake of Pb by
terrestrial organisms, the physiological effects of Pb, and the factors that modify terrestrial
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organism responses to Pb. Section AX7.1.4 outlines and highlights the critical recent
advancements in the understanding of the toxicity of Pb to terrestrial organisms. This section
begins with a summary of the conclusions from the 1986 Lead AQCD (U.S. Environmental
Protection Agency, 1986a) and then summarizes the more recent critical research conducted on
effects of Pb on primary producers, consumers, and decomposers. All concentrations are
expressed as mg Pb/kg soil dw, unless otherwise indicated.
Lead exposure may adversely affect organisms at different levels of organization, i.e.,
individual organisms, populations, communities, or ecosystems. Generally, however, there is
insufficient information available for single materials in controlled studies to permit evaluation
of specific impacts on higher levels of organization (beyond the individual organism). Potential
effects at the population level or higher are, of necessity, extrapolated from individual level
studies. Available population, community, or ecosystem level studies are typically conducted at
sites that have been contaminated or adversely affected by multiple stressors (several chemicals
alone or combined with physical or biological stressors). Therefore, the best documented links
between lead and effects on the environment are with effects on individual organisms. Impacts
on terrestrial ecosystems are discussed in Section 7.1.5 and Annex AX7.1.5.
The summary of recent critical advancements in understanding toxicity relies heavily on
the work completed by a multi-stakeholder group, consisting of federal, state, consulting,
industry, and academic participants, led by the EPA to develop Ecological Soil Screening Levels
(Eco-SSLs). Eco-SSLs describe the concentrations of contaminants in soils that would result in
little or no measurable effect on ecological receptors (U.S. Environmental Protection Agency,
2005a). They were developed by the U.S. EPA for use in screening-level assessments at
Superfund sites to identify contaminants requiring further evaluation in an ecological risk
assessment and were not designed to be used as cleanup target levels. The Eco-SSLs are
intentionally conservative in order to provide confidence that contaminants, which could present
an unacceptable risk, are not screened out early in the evaluation process. That is, at or below
these levels, adverse effects are considered unlikely. Eco-SSLs were derived for terrestrial
plants, soil invertebrates, birds, and mammals. Detailed procedures using an extensive list of
acceptability and exclusion criteria (U.S. Environmental Protection Agency, 2005a) were used in
screening the toxicity studies to ensure that only those that met minimum quality standards were
used to develop the Eco-SSLs. In addition, two peer reviews were completed during the
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Eco-SSL development process. The first was a consultation with the EPA Science Advisory
Board (SAB) in April 1999, and the second was a peer review workshop in July 2000, which was
open to the public.
Several conservative factors were incorporated into the development of the Eco-SSLs.
For the plant and invertebrate Eco-SSLs, studies were scored to favor relatively high
bioavailability. For wildlife Eco-SSLs, only species with a clear exposure link to soil were
considered (generalist species, species with a link to the aquatic environment, or species which
consume aerial insects were excluded), simple diet classifications were used (100% plants, 100%
earthworms or 100% animal prey) when in reality wildlife consume a varied diet, species were
assumed to forage exclusively at the contaminated site, relative bioavailability or Pb in soil and
diet was assumed to be 1, and the TRY was selected as the geometric mean of NOAELs unless
this value was higher than the lowest bounded LOAEL for mortality, growth or reproduction
(U.S. Environmental Protection Agency, 2005a,b).
Areas of research that were not addressed are effects from irrelevant exposure conditions
relative to airborne emissions of Pb (e.g., Pb shot, Pb paint, injection studies, studies conducted
on mine tailings, and studies conducted with hydroponic solutions); mixture toxicity (addressed
in Section AX7.1.3); issues related to indirect effects (e.g., effects on predator/prey interactions,
habitat alteration, etc.); and human health-related research (e.g., hypertension), which is
addressed in other sections of this document.
The toxicity data presented herein should be reviewed with a note of caution regarding
their relevance to field conditions. Laboratory studies, particularly those using Pb-spiked soil,
generally do not allow the soil to equilibrate following the addition of Pb and prior to the
addition of test organisms. This may result in increased bioavailability and overestimation of Pb
toxicity relative to actual environmental conditions (Davies et al., 2003).
AX7.1.3.1 Summary of Conclusions from the 1986 Lead Criteria Document
The 1996 Lead AQCD, Volume II (U.S. Environmental Protection Agency, 1986a)
reviewed the literature on the toxicity of Pb to plants, soil organisms, birds, and mammals.
The main conclusions from that document are provided below.
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Primary Producers
Commonly reported effects of Pb on vascular plants include the inhibition of
photosynthesis, respiration, and/or cell elongation, all of which reduce plant growth. However, it
was noted that studies of other effects on plant processes such as maintenance, flowering, and
hormone development had not been conducted; therefore, no conclusion could be reached
concerning effects of Pb on these processes.
The EPA (U.S. Environmental Protection Agency, 1986a) concluded that most plants
experience reduced growth when Pb concentrations in soil moisture (the film of moisture
surrounding soil particles in the root zone of soil) exceed 2 to 10 mg/kg. It also was concluded
that most plants would experience reduced growth (inhibition of photosynthesis, respiration, or
cell elongation) in soils of 310,000 mg/kg when soil composition and pH are such that
bioavailability of Pb in the soil is low (see Section AX7.1.3 for details on factors affecting
bioavailability of Pb in soil). Acid soils or soils with low organic matter tend to increase Pb
bioavailability and would inhibit plants at much lower Pb concentrations (e.g., as low as
<100 mg/kg).
Many effect levels have been reported at Pb concentrations much lower than
10,000 mg/kg soil. For example, effects on rye grass (Lolium rigidum) exposed to Pb in soil
included inhibition of germinating root elongation (at <2.5 mg/kg), absence of root growth
(at 5 mg/kg), or 55% inhibition of seed germination (at 20 to 40 mg/kg). Stunted growth in
radish (Raphanus sativus) was observed at 1000 mg/kg soil, with complete growth inhibition at
5000 mg/kg, when Pb was added as Pb-chloride; effects were less severe when the Pb was added
as Pb-oxide.
Consumers
The EPA (U.S. Environmental Protection Agency, 1986a) concluded that food is the
largest contributor of Pb to animals, with inhalation rarely accounting for more than 10 to 15%
of daily intake of Pb and drinking water exposures being quite low. It also was concluded that a
regular dose of 2 to 8 mg/kg-day causes death in most animals. Grazing animals may consume
more than 1 mg/kg-day in habitats near smelters and roadsides, but no toxic effects were
documented in these animals.
AX7-60
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Decomposers
Lack of decomposition has been observed as a particular problem around smelter sites.
Lead concentrations between 10,000 and 40,000 mg/kg soil can eliminate populations of
decomposer bacteria and fungi (U.S. Environmental Protection Agency, 1986a). Lead may
affect decomposition processes by direct toxicity to specific groups of decomposers, by
deactivating enzymes excreted by decomposers to break down organic matter, or by binding with
the organic matter and rendering it resistant to the action of decomposers.
Microorganisms are more sensitive than plants to Pb in soil. Delayed decomposition may
occur at between 750 and 7500 mg/kg soil (depending on soil type and other conditions).
Nitrification is inhibited by 14% at 1000 mg/kg soil.
U.S. Environmental Protection Agency Staff Review of 1986 Criteria Document
The EPA reviewed the 1986 Lead AQCD and presented an overall summary of
conclusions and recommendations (U.S. Environmental Protection Agency, 1990). The major
conclusion was that available laboratory and field data indicated that high concentrations of Pb
can affect certain plants and alter the composition of soil microbial communities. It was noted
that few field studies were available in which Pb exposures and associated effects in wildlife
were reported.
AX7.1.3.2 Recent Studies on the Effects of Lead on Primary Producers
Several studies published since 1986 have reported terrestrial plant exposure to Pb in soil,
many of which were reviewed during the development of the Eco-SSLs (U.S. Environmental
Protection Agency, 2005b). The relevant information from the Eco-SSL document (U.S.
Environmental Protection Agency, 2005b) is summarized below. A literature search and review
also was conducted to identify critical papers published since 2002, which is when the literature
search was completed for Eco-SSL development, and no new papers were identified as critical to
the understanding of Pb toxicity to terrestrial primary producers.
Effects observed in studies conducted since the 1986 Lead AQCD are similar to those
reported previously and include decreased photosynthetic and transpiration rates and decreased
growth and yield (U.S. Environmental Protection Agency, 2005b). The phytotoxicity of Pb is
considered relatively low, due to the limited availability and uptake of Pb from soil and soil
AX7-61
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solution and minimal translocation of Pb from roots to shoots (Pahlsson, 1989). Although many
laboratory toxicity studies have reported effects on plants, there are few reports of phytotoxicity
from Pb exposure under field conditions. For example, Leita et al. (1989) and Sieghardt (1990)
reported high concentrations of Pb and other metals in soil and vegetation collected around
mining areas in Europe, with no toxicity symptoms observed in plants or fruit.
The literature search completed for the terrestrial plant Eco-SSL development identified
439 papers for detailed review, of which 28 met the minimum criteria (U.S. Environmental
Protection Agency, 2005a). Thirty ecotoxicological endpoints were gleaned from these 28
papers and were further evaluated; most of those evaluated growth (biomass), which was
considered the most sensitive and ecologically relevant endpoint (U.S. Environmental Protection
Agency, 2005b). Five of the endpoints, representing four species tested under three different
combinations of pH and organic matter content, were used to develop the Eco-SSL of 120 mg/kg
(115 mg/kg rounded to two significant digits) (Table AX7-1.3.1).
Table AX7-1.3.1. Plant Toxicity Data Used to Develop the Eco-SSL
Plant Species
Loblolly pine (Pinus taeda)
Red maple (Acer rubrum)
Berseem clover
(Trifolium alexandrium)
Berseem clover
Rye grass (Lolium rigidum)
Soil pH
4
4
6.3
6.7
5.6
% Organic
Matter
2.5
2.5
0.94
3.11
0.1
Toxicity
Parameter
MATC* (growth)
MATC (growth)
MATC (growth)
MATC (growth)
MATC (growth)
Geometric Mean
Pb in Soil
(mg/kg dw)
144
144
316
141
22
115
*MATC = Maximum Acceptable Threshold Concentration, or the geometric mean of the NOAEC
(no-observed-adverse-effect concentration) and LOAEC (lowest-observed-adverse-effect concentration).
Source: U.S. Environmental Protection Agency (2005b).
The 25 ecotoxicological endpoints that were not used to develop the Eco-SSL for plants
are presented in Table AX7-1.3.2. The first six endpoints were considered eligible for Eco-SSL
derivation but were not used; the remainder did not meet all of the requirements to be considered
for inclusion in the Eco-SSL derivation process.
AX7-62
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Table AX7-1.3.2. Plant Toxicity Data Not Used to Develop the Eco-SSL
Plant Species Soil pH
Studies eligible for Eco-SSL derivation,
Berseem clover
(Trifolium alexandrium)
Tomato
(Lycopericon esculentum)
Tomato
Fenugreek
(Trigonella foenum-graecum)
Spinach (Spinacea oleracea)
Com (Zea mays)
Sow thistle (Sonchus oleraceus)
but not used
6.7
7.73
8.20
8.3
6.7
6.5
7.23
% Organic
Matter
3.11
1.70
0.86
0.5
3.0
2.1
1.6
Toxicity Parameter
MATC
MATC
MATC
MATC
MATC
MATC
MATC
Pb in Soil
(mg/kg dw)
141
71
71
283
424
158
2,263
Studies not eligible for Eco-SSL derivation
Loblolly pine (Finns taeda)
Red oak (Quercus rubra)
Spinach
Alfalfa (Medicago sativa)
Alfalfa
Alfalfa
Radish (Raphanus sativus)
Radish
Radish
Onion (Allium cepa)
Radish
Carrot (Daucus carota)
Peas (Pisum sativum)
Barley (Hordeum vulgare)
Alfalfa
Tomato
Spinach
Radish
Radish
5.5
6
6.7
6.4
6.9
6.9
6.9
6.9
6.9
8.3
5.1
7.0
7.0
6.0
6.9
7.45
6.7
6.2
7.1
3.4
1.5
0.0
1.0
1.7
1.7
1.0
1.0
1.0
0.5
8.0
0.6
0.6
2.5
4.8
2.06
8.0
8.0
8.0
NOAEC
LOAEC
NOAEC
NOAEC
NOAEC
NOAEC
LOAEC
LOAEC
LOAEC
LOAEC
NOAEC
NOAEC
NOAEC
NOAEC
NOAEC
MATC
NOAEC
NOAEC
NOAEC
480
100
600
250
250
250
500
100
100
50
600
85
85
1,000
250
35
600
600
600
*MATC = Maximum Acceptable Threshold Concentration, or the geometric mean of the NOAEC
(no-observed-adverse-effect concentration) and LOAEC (lowest-observed-adverse-effect concentration).
Source: U.S. Environmental Protection Agency (2005b).
AX7-63
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AX7.1.3.3 Recent Studies on the Effects of Lead on Consumers
Since the 1986 Lead AQCD (U.S. Environmental Protection Agency, 1986a), there have
been several studies in which birds and mammals were exposed to Pb via ingestion (primarily
through dietary Pb). Many of these were reviewed during development of the Eco-SSLs (U.S.
Environmental Protection Agency, 2005b). The relevant information from the Eco-SSL
document (U.S. Environmental Protection Agency, 2005b) is described below. A literature
search and review was conducted to identify critical papers published since 2002. These recent
critical papers are described briefly below. No studies were found that used inhalation exposures
to evaluate endpoints such as survival, growth, and reproduction in birds or mammals. All
studies described below exposed organisms via ingestion (drinking water or diet) or gavage.
The Eco-SSLs for avian and mammalian consumers are presented as Pb concentrations in
soil. These concentrations were calculated by assuming exposure to Pb via incidental soil
ingestion and ingestion of Pb-contaminated food, and using aNOAEL as the TRV (U.S.
Environmental Protection Agency, 2005a). A simplified version of the equation used to
calculate the Eco-SSL is:
TRV
where:
HQ = hazard quotient (1 mg Pb/kg bw/day)
Csoii = concentration of Pb in soil (mg Pb/kg soil)
IRsoii = incidental soil ingestion rate (kg soil/day)
Cfood = concentration of Pb in food (mg Pb/kg food)
IRfood = food ingestion rate (kg food/day)
BW = body weight (kg)
TRV = toxicity reference value (mg Pb/kg bw/day)
Food ingestion was estimated by modeling the uptake of Pb from soil into each diet
component (e.g., vegetation, invertebrates, etc.). Bioavailability of Pb in soil and food was
assumed to be 100%. The Eco-SSL is equivalent to the concentration of Pb in soil that results in
an HQ = 1 . The two factors that may have the most significant influence on the resulting Eco-
SSL are the assumption of 100% bioavailability of Pb in soil and diet and the selection of the
AX7-64
-------
TRY. The toxicity data that were reviewed to develop the TRY are presented in the following
subsections.
Representative avian and mammalian wildlife species were selected for modeling Pb
exposures to wildlife with different diets and calculating the Eco-SSL. The avian species
selected were dove (herbivore), woodcock (insectivore), and hawk (carnivore). The mammalian
species selected were vole (herbivore), shrew (insectivore), and weasel (carnivore). The lowest
of the three back-calculated soil concentrations, which resulted in an HQ = 1, was selected as the
Eco-SSL. For Pb, the lowest values were for the insectivorous species of bird and mammal.
Avian Consumers
Effects on birds observed in studies conducted since the 1986 Lead AQCD (U.S.
Environmental Protection Agency, 1986a) are similar to those reported previously: mortality,
changes in juvenile growth rate and weight gain, effects on various reproductive measures, and
changes in behavior (U.S. Environmental Protection Agency, 2005b). Reproductive effects
following Pb exposure included declines in clutch size, number of young hatched, and number of
young fledged as well as decreased fertility or eggshell thickness. Few significant reproductive
effects have been reported in birds at Pb concentrations below 100 mg/kg in the diet
(Scheuhammer, 1987).
The literature search completed for Eco-SSL development identified 2,429 papers for
detailed review for either avian or mammalian species, of which 54 met the minimum criteria for
further consideration for avian Eco-SSL development (U.S. Environmental Protection Agency,
2005b). The 106 toxicological data points for birds that were further evaluated included
biochemical, behavioral, physiological, pathological, reproductive, growth, and survival effects.
Growth and reproduction data were used to derive the Eco-SSL (Table AX7-1.3.3;
Figure AX7-1.3.1). The geometric mean of the NOAELs was calculated as 10.9 mg/kg-day,
which was higher than the lowest bounded LOAEL (the term "bounded" means that both a
NOAEL and LOAEL were obtained from the same study). Therefore, the highest bounded
NOAEL that was lower than the lowest bounded LOAEL for survival, growth, or reproduction
(1.63 mg Pb/kg bw-day) was used as the TRY (U.S. Environmental Protection Agency, 2005b).
The TRY was used to back-calculate the Eco-SSL of 11 mg/kg soil for avian species (U.S.
AX7-65
-------
Table AX7-1.3.3. Avian Toxicity Data Used to Develop the Eco-SSL
X
ON
ON
Avian No. of
Species Doses
Reproduction
Japanese 4
quail
Chicken 3
Chicken 4
Mallard 2
American 3
kestrel
Japanese 5
quail
Japanese 5
quail
Japanese 3
quail
Japanese 5
quail
Japanese 4
quail
Chicken 5
Ringed 2
turtle dove
Japanese 2
quail
Japanese 2
quail
Route of
Exposure
FD
FD
FD
FD
FD
FD
FD
FD
FD
FD
FD
DR
FD
FD
Exposure
Duration
5
4
30
76
6
5
5
32
12
12
10
11
1
27
Duration
Units Age
w 6
w NR
d 22
d NR
mo 1-6
w 6
w 1
d NR
w 0
w NR
w NR
w NR
w 14
d NR
Age
Units
w
NR
w
NR
yr
d
d
NR
d
NR
NR
NR
w
NR
Lifestage
LB
LB
LB
SM
AD
JV
JV
AD
LB
LB
LB
AD
JV
AD
Sex
F
F
F
F
F
M
M
F
B
F
F
M
F
F
Effect
Type
REP
REP
EGG
EGG
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
Effect
Measure
PROG
PROG
ALWT
ESTH
RSUC
TEWT
TEWT
PROG
EGPN
PROG
PROG
TEWT
TPRD
PROG
NOAEL
Response (nig/kg
Site bw/day)
WO 0.194
WO 1.63
EG 2.69
EG 5.63
WO 12.0
TE 12.6
TE 67.4
WO 125
EG
WO
WO
TE
WO
WO
LOAEL
(mg/kg
bw/day)
1.94
3.26
4.04
126
135
0.110
0.194
3.26
11.8
93.1
377
-------
Table AX7-1.3.3 (cont'd). Avian Toxicity Data Used to Develop the Eco-SSL
Avian
Species
Growth
Japanese
quail
Japanese
quail
Japanese
quail
Japanese
quail
J> Chicken
X
7^ Chicken
Oi
Japanese
quail
Japanese
quail
Japanese
quail
Japanese
quail
Chicken
Duck
American
kestrel
Chicken
Japanese
quail
No. of
Doses
3
3
2
3
4
4
5
5
5
5
2
3
4
2
5
Route of
Exposure
FD
FD
FD
FD
FD
FD
FD
FD
FD
FD
FD
GV
GV
FD
FD
Exposure
Duration
5
2
2
4
4
4
12
12
2
1
21
3
10
20
14
Duration
Units Age
w 1
w 1
w 1
w 0
w 4
w 4
w 0
w 1
w 6
w 1
d 1
mo 24
d 1
d 1
d 1
Age
Units
d
d
d
d
w
w
d
w
d
d
d
w
d
d
d
Lifestage
JV
JV
JV
JV
JV
JV
JV
JV
JV
JV
JV
MA
JV
JV
JV
Sex
F
B
NR
F
NR
NR
F
F
NR
NR
B
F
NR
B
B
Effect
Type
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
Effect
Measure
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
Response
Site
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
NOAEL
(mg/kg
bw/day)
1.56
2.77
4.64
5.93
6.14
7.W
11.1
11.2
12.6
13.5
14.2
20.0
25.0
28.4
34.5
LOAEL
(mg/kg
bw/day)
15.6
59.3
61.4
71.0
111
112
126
67.4
125
-------
Table AX7-1.3.3 (cont'd). Avian Toxicity Data Used to Develop the Eco-SSL
X
ON
OO
Avian
Species
American
kestrel
Chicken
Mallard
Chicken
Chicken
Japanese
quail
Chicken
Chicken
Chicken
Chicken
Chicken
Chicken
Chicken
Chicken
Chicken
No. of
Doses
4
5
4
5
2
3
2
3
4
2
2
2
2
2
2
Route of
Exposure
FD
FD
FD
FD
FD
FD
FD
FD
FD
FD
OR
FD
FD
FD
FD
Exposure
Duration
60
2
8
20
3
32
19
2
14
20
4
7
2
7
14
Duration
Units
d
w
d
d
w
d
d
w
d
d
w
d
w
d
d
Age
1-2
1
9
1
1
NR
1
1
8
1
NR
1
1
1
8
Age
Units
yr
d
d
d
d
NR
d
d
d
d
NR
d
d
d
d
Lifestage
AD
JV
JV
JV
JV
AD
JV
JV
JV
JV
JV
JV
JV
IM
JV
Sex
B
M
NR
M
M
F
M
M
M
M
B
M
M
NR
M
Effect
Type
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
Effect
Measure
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
NOAEL
Response (nig/kg
Site bw/day)
WO 54.3
WO 61.3
WO 66.9
WO
WO
WO
WO
WO
WO
WO
WO
WO
WO
WO
WO
LOAEL
(mg/kg
bw/day)
123
38.2
53.1
64.3
76.3
124
152
163
200
262
270
273
282
AD = adult; ALWT = albumin weight; B = both; BDWT = body weight changes; d = days; DR = drinking water; EG = egg; EGG = effects on eggs; EGPN = egg production; ESTH = eggshell
thinning; F = female; FD = food; GRO = growth; GV = gavage; JV = juvenile; LB = laying bird; MA = mature; M = male; mo = months; NR = not reported; OR = other oral; PROG = progeny counts
or numbers; REP = reproduction; RSUC = reproductive success; SM = sexually mature; TE = testes; TEWT = testes weight; TPRD = total production; w = weeks; WO = whole organism; yr = years.
Source: U.S. Environmental Protection Agency (2005b)
-------
IUUIJ
*>.
(B -inn
^ 100
.Q
0)
^
SS 10
O)
0
(0
0 1
0
n 1
oooo
o
A&AO oo o°
oo°A o A 0.« oo°
•"• °
AA..««*A
• ••
•* Legend:
AA A
A • Growth NOAEL
0 Growth LOAEL
A Reproduction NOAEL
A Reproduction LOAEL
A A - Eco-SSL (mg/kg dw)
A,
Reproduction and Growth
Figure AX7-1.3.1. Avian reproduction and growth toxicity data considered in
development of the Eco-SSL.
Source: U.S. Environmental Protection Agency (2005b).
Environmental Protection Agency, 2005b). For more information on the rationale for selecting
TRVs, please refer to U.S. Environmental Protection Agency (2003).
Many of the toxicity data presented in the Eco-SSL document (U.S. Environmental
Protection Agency, 2005b) are lower than those discussed in the 1986 Lead AQCD. The TRV
and resulting Eco-SSL were derived using many conservative assumptions. For example, the
EPA (U.S. Environmental Protection Agency, 2005b) recognizes that toxicity is observed over a
wide range of doses (100 mg Pb/kg bw/day), even when considering only reproductive
effects in the same species. In addition, the TRV of 1.63 mg/kg-day is lower than most of the
reported doses that have been associated with measured effects. This is true for not only
survival, growth, and reproductive effects but also biochemical, behavioral, physiological, and
pathological effects, which generally are observed at lower concentrations than effects on growth
or reproduction. In addition, the Eco-SSL was back-calculated using conservative modeling
assumptions. Therefore, the Eco-SSL of 11 mg/kg may be considered a conservative value.
AX7-69
-------
Very little research has been done to expand the knowledge of the toxicity of Pb to birds
since the Eco-SSL work was done. However, several studies have been conducted on waterfowl.
Toxicity data for waterfowl (in particular, mallards) were included in the soil Eco-SSL
development process (Table AX7-1.3.3), although mallards may be more exposed to
contaminants in sediment than soil. Effects on waterfowl may vary depending on the form of Pb,
characteristics of the sediment, the foraging strategy of the species (which may vary during
reproduction), and the nutritional status of the animal. Sediment is recognized as an important
route of exposure for waterfowl, particularly those species that dabble (i.e., forage on
invertebrates in the sediment) (Beyer et al., 2000; Douglas-Stroebel et al., 2005). Douglas-
Stroebel et al. (2005) found that mallard ducklings exposed to Pb-contaminated sediment and a
low nutrition diet exhibited more changes in behavior (as measured by time bathing, resting, and
feeding) than Pb exposure or low nutrition exposure alone. These effects may be due to the low
nutrition diet being deficient in levels of protein, amino acids, calcium, zinc, and other nutrients.
Beyer et al. (2000) related blood Pb to sublethal effects in waterfowl along the Coeur
d=Alene River near a mining site in Idaho. The authors suggested that 0.20 mg/kg ww blood Pb
represents the no-effect level. This no-effect blood concentration corresponds to a sediment Pb
concentration of 24 mg/kg. A sediment concentration of 530 mg/kg, associated with a blood Pb
concentration of 0.68 mg/kg ww, is suggested to be the lowest-effect concentration. These
results are consistent with those of Scheuhammer (1989) who found blood Pb concentrations of
0.18 |ig/mL to 0.65 |ig/mL in mallards corresponded to conditions associated with greater than
normal exposure to Pb, but that that should not be considered Pb poisoning. The study by Beyer
et al. (2000) related blood Pb to waterfowl mortality and concluded that some swan mortality
may occur at blood Pb levels of 1.9 mg/kg ww, corresponding to a sediment Pb concentration of
1800 mg/kg. Using the mean blood level of 3.6 mg/kg ww from all moribund swans in the
study, it was predicted that half of the swans consuming sediment at the 90th percentile rate
would die with chronic exposure to sediment concentrations of 3600 mg/kg.
Mammalian Consumers
Effects on mammals observed in studies conducted since the 1986 Lead AQCD (U.S.
Environmental Protection Agency, 1986a) are similar to those reported previously: mortality,
effects on reproduction, developmental effects, and changes in growth (U.S. Environmental
AX7-70
-------
Protection Agency, 2005b). Very little research has been done to expand the knowledge of the
toxicity of Pb to mammalian wildlife, since the Eco-SSL work was done. Most studies
conducted on mammals use laboratory animals to study potential adverse effects of concern for
humans, and such studies are summarized in other sections of this document.
Of the 2,429 papers identified in the literature search for Eco-SSL development, 219 met
the minimum criteria for further consideration for mammalian Eco-SSL development (U.S.
Environmental Protection Agency, 2005b). The 343 ecotoxicological endpoints for mammals
that were further evaluated included biochemical, behavioral, physiological, pathological,
reproductive, growth, and survival effects. Growth and reproduction data were used to derive
the Eco-SSL (Table AX7-1.3.4, Figure AX7-1.3.2). The geometric mean of the NOAELs was
calculated as 40.7 mg/kg-day, which was higher than the lowest bounded LOAEL for survival,
growth, or reproduction. Therefore, the highest bounded NOAEL that was lower than the lowest
bounded LOAEL for survival, growth, or reproduction (4.7 mg Pb/kg bw-day) was used as the
TRV (U.S. Environmental Protection Agency, 2005b). The TRV was used to back-calculate the
Eco-SSL of 56 mg/kg soil (U.S. Environmental Protection Agency, 2005b). For more
information on the rationale for selecting TRVs, please refer to U.S. Environmental Protection
Agency (2003).
A review of the data presented in the Eco-SSL document (U.S. Environmental Protection
Agency, 2005b) reveals that effects on survival generally are observed at Pb doses much greater
than those reported in the 1986 Lead AQCD, where it was concluded that most animals would
die when consuming a regular dose of 2 to 8 mg Pb/kg bw-day (U.S. Environmental Protection
Agency, 1986a). However, the data presented in the Eco-SSL document (U.S. Environmental
Protection Agency, 2005b) generally do not support this. While five studies reported decreased
survival at these levels, 34 other studies reported no mortality or a LOAEL for mortality at
significantly higher doses (U.S. Environmental Protection Agency, 2005b). The five studies that
supported this low toxic level were conducted on three species (mouse, rat, and cow) and used
either gavage or drinking water as the exposure method. The 34 other studies included data on
these three species as well as five other species (rabbit, dog, pig, hamster, and shrew) and
included gavage and drinking water as well as food ingestion exposure methods. The NOAELs
for survival ranged from 3.5 to 3200 mg/kg-day (U.S. Environmental Protection Agency,
2005b). Therefore, the review of data in the Eco-SSL document suggests effects on survival of
AX7-71
-------
Table AX7-1.3.4. Mammalian Toxicity Data Used to Develop the Eco-SSL
Mammalian
Species
Reproduction
Rat
Rat
Rat
Rat
Sheep
Rat
h,^ Guinea pig
^ Rat
i
to Rat
Rat
Cotton rat
Rat
Rat
Rat
Rat
Rat
Rat
Rat
Rat
Rat
No. of
Doses
5
6
3
4
3
6
3
5
4
5
3
4
3
2
4
4
3
4
5
4
Route of
Exposure
DR
DR
DR
DR
FD
DR
DR
FD
DR
DR
DR
GV
DR
FD
DR
DR
DR
GV
DR
DR
Exposure
Duration
62
21
35
62
27
21
40
92
23.8
23.8
7
9
100
35
60
56
31
41
1
30
Duration
Units
d
d
d
d
w
d
d
w
d
d
w
w
d
d
d
d
d
d
w
d
Age
21
NR
NR
21
NR
NR
NR
21
21
21
NR
10
21
70
NR
70
NR
NR
94
NR
Age
Units
d
NR
NR
d
NR
NR
NR
d
d
d
NR
w
d
d
NR
d
NR
NR
d
NR
Lifestage
GE
GE
AD
GE
GE
GE
GE
JV
LC
GE
AD
JV
GE
LC
SM
LC
LC
GE
JV
SM
Sex
F
F
M
B
F
F
F
M
F
F
M
M
F
F
M
F
F
F
M
M
Effect
Type
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
Effect
Measure
PRWT
PRWT
RSUC
PRWT
RSUC
PRWT
PRWT
TEWT
Other
Other
RHIS
SPCV
PRWT
PRWT
TEWT
PROG
PRWT
PRWT
SPCL
Other
Response
Site
wo
wo
wo
wo
wo
wo
wo
TE
WO
WO
RT
TE
WO
WO
TE
WO
WO
WO
SM
SV
NOAEL
(mg/kg
bw/day)
0.71
1.00
2.60
3.00
4.50
5.00
5.50
7.50
8.90
9.10
12.4
18.0
25.4
27.5
31.6
32.5
33.3
41.0
47.3
56.0
LOAEL
(mg/kg
bw/day)
7.00
5.00
26.0
6.0
—
10.0
—
74.9
45.0
170
180
—
—
63.2
—
Ill
54.6
82.0
285
-------
Table AX7-1.3.4 (cont'd). Mammalian Toxicity Data Used to Develop the Eco-SSL
Mammalian
Species
Hamster
Hamster
Rat
Rat
Rat
Rat
Rat
Mouse
K> Mouse
>Ij Mouse
OJ
Rat
Rat
Rat
Rat
Rat
Rat
Mouse
Rat
Rat
Mouse
Mouse
Rat
No. of
Doses
2
2
4
5
3
4
2
3
7
7
4
5
2
2
4
4
4
3
2
2
4
2
Route of
Exposure
DR
DR
DR
GV
DR
DR
DR
FD
FD
FD
DR
DR
GV
DR
FD
DR
GV
FD
DR
DR
GV
DR
Exposure
Duration
51
14
37
12
68
77
21
8
30
30
21
10
102
9
4
13
60
339
9
6
52
120
Duration
Units
d
d
d
d
d
d
d
w
d
d
d
w
d
mo
d
w
d
d
mo
mo
d
d
Age
15
11
NR
NR
25
25
NR
2
NR
NR
NR
NR
30
NR
NR
NR
NR
26-27
21
21
2
1
Age
Units
w
w
NR
NR
d
d
NR
mo
NR
NR
NR
NR
d
NR
NR
NR
NR
d
d
d
mo
d
Lifestage
GE
GE
GE
GE
GE
GE
LC
GE
LC
LC
GE
AD
GE
SM
LC
]V
AD
3V
JV
JV
GE
GE
Sex
F
F
F
F
F
F
F
M
F
F
F
M
F
M
F
M
F
B
F
F
F
M
Effect
Type
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
Effect
Measure
PROG
PROG
PRWT
RSEM
PRWT
PRWT
PRWT
SPCV
PRWT
PRWT
DEYO
TEWT
PRWT
RHIS
PRWT
PERT
RPRD
PRWT
DEYO
DEYO
PROG
SPCL
Response
Site
wo
wo
wo
EM
WO
wo
wo
TE
WO
WO
WO
MT
WO
TE
WO
WO
0V
WO
WO
WO
EM
TE
NOAEL
(mg/kg
bw/day)
64.8
64.9
90.1
100
115
116
120
144
202
202
276
294
441
600
601
639
—
—
—
—
—
_
LOAEL
(mg/kg
bw/day)
—
—
270
150
—
—
—
1,440
506
506
552
587
—
—
1,500
—
2.00
2.49
2.94
3.62
5.50
6.76
-------
Table AX7-1.3.4 (cont'd). Mammalian Toxicity Data Used to Develop the Eco-SSL
X
Mammalian
Species
Mouse
Mouse
Rat
Rat
Rat
Rat
Mouse
Mouse
Mouse
Mouse
Mouse
Rat
Rat
Rat
Rat
Rat
Rat
Rat
Rat
Rat
Rat
Rat
No. of
Doses
2
2
2
2
2
3
2
2
2
2
4
2
5
2
3
2
2
4
2
4
3
2
Route of
Exposure
DR
GV
FD
GV
DR
DR
DR
DR
DR
DR
FD
DR
DR
DR
DR
DR
DR
FD
FD
FD
FD
DR
Exposure
Duration
5
2
102
3
18
90
23
62
18
12
18
4
6
22
30
13
21
3
1
3
25
21
Duration
Units
w
w
d
mo
d
d
d
d
w
w
d
w
w
d
d
w
d
w
w
w
d
d
Age
NR
NR
NR
8
NR
NR
NR
NR
6-8
9
NR
99
4
NR
52
NR
80
NR
19
NR
NR
NR
Age
Units
NR
NR
NR
w
NR
NR
NR
NR
w
w
NR
d
mo
NR
d
NR
d
NR
w
NR
NR
NR
Lifestage
AD
JV
GE
SM
GE
AD
GE
GE
LC
SM
GE
JV
GE
GE
JV
GE
JV
LC
LC
LC
LC
LC
Sex
M
M
F
M
F
M
F
F
F
M
F
M
F
F
M
F
F
F
F
F
F
F
Effect
Type
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
Effect
Measure
TEDG
SPCL
PROG
TEDG
PRWT
SPCL
PRWT
PRWT
PRWT
PRFM
PRWT
SPCL
RHIS
PRWT
GREP
PRWT
PRWT
PRWT
PRWT
PRWT
PRWT
PRWT
Response
Site
TE
SM
WO
TE
WO
SM
WO
wo
wo
wo
wo
SM
WO
wo
PG
WO
WO
wo
wo
wo
wo
wo
NOAEL LOAEL
(mg/kg (mg/kg
bw/day) bw/day)
— 16.6
— 46.4
— 49.6
— 50.0
— 55.5
— 61.2
— 78.6
— 99.8
— 137
— 139
— 154
— 171
— 175
— 178
— 198
— 200
— 218
— 221
— 222
— 230
— 258
— 330
-------
Table AX7-1.3.4 (cont'd). Mammalian Toxicity Data Used to Develop the Eco-SSL
X
Mammalian
Species
Rat
Rat
Rat
Rat
Rat
Mouse
Mouse
Rat
Mouse
Rat
Mouse
Rat
Rat
Rat
Mouse
Rat
Rat
Mouse
Rat
Rat
Rat
Mouse
No. of
Doses
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
4
Route of
Exposure
DR
DR
DR
DR
DR
DR
DR
DR
DR
DR
DR
DR
DR
DR
FD
DR
DR
DR
FD
FD
FD
DR
Exposure
Duration
30
17
24
12
30
44
14
50
45
22
48
9
9
3
7
126
20
4
2
7
21
18
Duration
Units
d
d
d
d
d
d
d
d
d
d
d
mo
mo
w
d
d
w
d
w
d
d
w
Age
52
NR
NR
NR
27
NR
NR
24
50-100
NR
NR
3
NR
14
NR
1
10
NR
NR
NR
NR
11
Age
Units
d
NR
NR
NR
d
NR
NR
d
d
NR
NR
mo
NR
w
NR
d
w
NR
NR
NR
NR
w
Lifestage
JV
GE
LC
GE
JV
GE
LC
JV
GE
GE
GE
SM
SM
LC
GE
GE
GE
LC
LC
LC
LC
JV
Sex
M
F
F
F
M
F
F
F
F
F
F
M
M
F
F
F
F
F
F
F
F
F
Effect
Type
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
REP
Effect
Measure
SPCL
PRWT
PRWT
PRWT
SPCL
PRWT
PRWT
RBEH
ODVP
PRWT
PRWT
SPCL
TEDG
PRWT
RSUC
PROG
PRWT
PRWT
PRWT
PRWT
PRWT
TEWT
Response
Site
SM
WO
wo
wo
SM
WO
wo
wo
wo
wo
wo
TE
TE
WO
EM
WO
WO
WO
wo
wo
wo
wo
NOAEL LOAEL
(mg/kg (mg/kg
bw/day) bw/day)
— 354
— 360
— 360
— 362
— 364
— 381
— 381
— 381
— 404
— 420
— 437
— 579
— 600
— 635
— 646
— 651
— 750
— 762
— 828
— 833
— 991
— 1,370
-------
Table AX7-1.3.4 (cont'd). Mammalian Toxicity Data Used to Develop the Eco-SSL
Mammalian
Species
Rat
Mouse
Rat
Rat
Rat
Rat
Mouse
Rat
K> Growth
^j Horse
Oi
Rat
Rat
Rat
Cattle
Rat
Rat
Rat
Dog
Rat
Rat
Cattle
Rat
No. of
Doses
2
2
2
2
2
M
2
2
2
2
6
5
4
3
2
4
3
3
4
3
2
Route of
Exposure
FD
DR
FD
FD
FD
FD
DR
FD
FD
FD
DR
DR
OR
DR
DR
DR
FD
DR
DR
OR
OR
Exposure
Duration
30
14
16
7
25
27
14
17
15
21
21
7
7
14
332
7
7
30
23
84
6
Duration
Units
d
w
d
d
d
d
w
d
w
d
d
d
w
d
d
w
mo
d
d
d
w
Age
NR
NR
NR
NR
NR
NR
21
NR
20-21
0
NR
50
1
21
28
21
NR
22-24
22
NR
NR
Age
Units
NR
NR
NR
NR
NR
NR
d
NR
w
d
NR
d
w
d
d
d
NR
d
d
NR
NR
Lifestage
LC
GE
LC
LC
LC
LC
W
LC
W
W
GE
AD
W
W
w
GE
W
W
w
w
AD
Sex
F
B
F
F
F
C
B
F
M
F
F
F
M
F
B
F
NR
M
F
M
M
Effect
Type
REP
REP
REP
REP
REP
REP
REP
REP
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
Effect
Measure
PRWT
PROG
PROG
PRWT
PRWT
PROG
PROG
PRWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
Response
Site
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
NOAEL
(mg/kg
bw/day)
—
—
—
—
—
—
—
—
0.15
0.5
1.00
1.27
1.99
2.40
2.98
4.70
4.71
5.64
5.80
7.79
9.10
LOAEL
(mg/kg
bw/day)
1,770
1,990
2,570
2,570
2,570
2,840
3,630
6,170
—
—
5.00
13.0
—
—
—
8.90
—
28.2
29.0
—
_
-------
Table AX7-1.3.4 (cont'd). Mammalian Toxicity Data Used to Develop the Eco-SSL
X
Mammalian
Species
Rat
Rat
Rabbit
Rat
Rat
Rat
Rat
Rat
Mouse
Rat
Rat
Rat
Rat
Rat
Sheep
Rat
Cattle
Rat
Rat
Rat
Rat
Rat
No. of
Doses
2
3
3
2
2
2
2
2
3
4
3
4
7
4
5
2
4
2
5
4
2
6
Route of
Exposure
GV
DR
GV
DR
DR
FD
OR
DR
DR
GV
FD
GV
DR
DR
FD
DR
FD
GV
DR
GV
FD
DR
Exposure
Duration
8
6
10
140
6
10
6
7
14
9
339
29
10
56
84
10
7
28
4
12
4
10
Duration
Units
w
mo
d
d
w
w
w
w
d
w
d
d
w
d
d
w
w
d
w
d
w
w
Age
NR
NR
1
21
NR
NR
NR
NR
0
10
26-27
NR
NR
70
NR
NR
16
2
94
2
NR
NR
Age
Units
NR
NR
d
d
NR
NR
NR
NR
d
w
d
NR
NR
d
NR
NR
w
d
d
d
NR
NR
Lifestage
JV
AD
JV
JV
JV
JV
AD
JV
JV
JV
JV
SM
JV
LC
JV
JV
JV
JV
JV
JV
JV
JV
Sex
F
M
F
M
M
M
M
M
NR
M
B
F
M
F
M
M
M
B
M
B
M
M
Effect
Type
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
Effect
Measure
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
Response
Site
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
NOAEL
(mg/kg
bw/day)
10.0
10.6
10.7
10.7
15.1
15.4
15.5
16.1
16.3
18.0
18.3
18.9
24.3
32.5
32.7
38.5
43.0
50.0
71.5
75.0
100
120
LOAEL
(mg/kg
bw/day)
—
532
50.4
—
—
—
—
—
163
180
—
—
—
—
—
—
—
—
178
225
—
383
-------
Table AX7-1.3.4 (cont'd). Mammalian Toxicity Data Used to Develop the Eco-SSL
Mammalian
Species
Mouse
Mouse
Mouse
Rat
Rat
Rat
Mouse
Rat
x Rat
^ Rat
oo
Rat
Rat
Mouse
Rat
Rat
Rat
Rat
Rat
Mouse
Mouse
Rat
Rat
No. of
Doses
3
2
2
3
2
4
3
4
2
2
4
4
5
2
4
5
2
2
4
7
2
2
Route of
Exposure
FD
DR
DR
DR
DR
GV
DR
GV
GV
DR
FD
DR
DR
DR
GV
GV
FD
GV
GV
FD
DR
DR
Exposure
Duration
4
18
12
30
4
18
6
18
91
21
1
30
10
30
14
14
14
102
12
30
126
20
Duration
Units
w
w
w
d
w
d
w
d
d
d
w
d
w
d
d
d
mo
d
d
d
d
w
Age
3
6-8
NR
52
99
3
7
2
NR
80
NR
NR
NR
52
14
20
0
30
6
NR
1
10
Age
Units
mo
w
NR
d
d
d
w
d
NR
d
NR
NR
NR
d
d
d
d
d
d
NR
d
w
Lifestage
JV
LC
GE
JV
JV
JV
SM
JV
JV
JV
LC
JV
JV
JV
JV
JV
JV
LC
JV
LC
GE
GE
Sex
B
F
M
M
B
M
M
B
M
F
F
M
M
M
NR
NR
NR
F
M
F
F
F
Effect
Type
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
Effect
Measure
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
Response
Site
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
NOAEL
(mg/kg
bw/day)
136
137
139
169
171
180
187
200
200
218
230
285
362
364
400
400
431
441
534
632
651
750
LOAEL
(mg/kg
bw/day)
1360
—
—
508
—
—
373
—
—
—
460
—
—
—
800
800
—
—
—
1264
—
_
-------
Table AX7-1.3.4 (cont'd). Mammalian Toxicity Data Used to Develop the Eco-SSL
Mammalian
Species
Mouse
Rat
Rat
Cattle
Rat
Rat
Rat
Rat
x Rat
^ Rat
VO
Mouse
Dog
Shrew
Rat
Pig
Rat
Rat
Rat
Rat
Rat
Rat
Rat
No. of
Doses
7
4
2
2
3
4
2
2
2
2
2
2
4
3
2
2
2
2
2
2
2
4
Route of
Exposure
FD
FD
DR
FD
DR
DR
DR
DR
DR
DR
GV
OR
FD
GV
FD
GV
FD
GV
DR
DR
GV
GV
Exposure
Duration
28
18
9
283
92
7
5
26
14
10
3
5
31
58
13
29
5
6
30
50
28
14
Duration
Units
d
d
d
d
d
d
d
d
d
d
w
w
d
d
w
d
w
d
d
d
d
d
Age
NR
NR
21
7
25
25
26
22
26
26
NR
<1
NR
2
4
2
NR
1
27
24
2
18
Age
Units
NR
NR
d
mo
d
d
d
d
d
d
NR
yr
NR
d
w
d
NR
d
d
d
d
d
Lifestage
LC
LC
3V
3V
GE
GE
3V
3V
3V
3V
3V
3V
3V
3V
3V
3V
MA
3V
3V
3V
3V
3V
Sex
F
F
M
M
F
F
F
F
F
F
M
NR
B
B
NR
F
NR
B
M
M
M
NR
Effect
Type
GRO
GRO
GRO
GRO
MPH
GRO
GRO
GRO
MPH
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
Effect
Measure
BDWT
BDWT
BDWT
BDWT
GMPH
BDWT
BDWT
BDWT
Other
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
Response
Site
wo
wo
wo
wo
TB
WO
WO
WO
TA
WO
WO
WO
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
NOAEL LOAEL
(mg/kg (mg/kg
bw/day) bw/day)
1260 2530
1500
— 3.30
— 15.0
— 28.7
— 29.0
— 29.0
— 29.5
— 29.9
— 30.4
— 46.4
— 50.0
— 61.5
— 100
— 173
— 200
— 272
— 328
— 354
— 371
— 400
— 400
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Table AX7-1.3.4 (cont'd). Mammalian Toxicity Data Used to Develop the Eco-SSL
Mammalia
n Species
Mouse
Rat
Rat
Mouse
Rat
Rat
Rat
^ Rat
1
oo
0 Rat
Rat
Rat
No. of
Doses
2
4
2
4
2
2
2
4
2
3
2
Route of
Exposure
DR
FD
DR
DR
FD
GV
FD
GV
FD
GV
FD
Exposure
Duration
45
1
6
10
21
18
2
14
2
14
14
Duration
Units
d
w
w
w
d
d
w
d
w
d
d
Age
50-100
NR
14
11
NR
2
0
24
60-80
16
60
Age
Units
d
NR
w
w
NR
d
d
d
d
d
d
Lifestage
GE
LC
LC
JV
LC
JV
JV
JV
JV
JV
JV
Sex
F
F
F
F
F
B
NR
NR
M
NR
M
Effec
t
Type
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
GRO
Effect
Measur
e
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
BDWT
Response
Site
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
wo
NOAEL LOAEL
(mg/kg (mg/kg
bw/day) bw/day)
— 404
— 442
— 638
— 748
— 991
— 1000
— 1430
— 1600
— 2390
— 2400
— 2650
AD = adult; B = both; BDWT = body weight changes; d = days; DEYO = death of young; DR = drinking water; F = female; FD = food; PERT = fertility; GMPH = general morphology;
GRO = growth; GV = gavage; JV = juvenile; LC = lactation; M = male; MA = mature; mo = months; MPH = morphology; NR = not reported; ODVP = offspring development; OR = other oral;
PG = prostate gland; PROG = progeny counts or numbers; PRWT = progeny weight; RBPH = reproductive behavior; REP = reproduction; RHIS = reproductive organ histology; RSEM = resorbed
embryos; RSUC = reproductive success (general); RT = reproductive tissue; SM = sexually mature; SPCL = sperm cell counts; SPCV = sperm cell viability; TA = tail; TB = tibia; TE = testes;
TEDG = testes degeneration; TEWT = testes weight; w = weeks; WO = whole organism; yr = years.
Source: U.S. Environmental Protection Agency (2005b).
-------
10000
>* 1000
ro
1
.0
t
I 10
3!
o
Q 1
100
0.1
Legend:
• Growth NOAEL
O Growth LOAEL
A Reproduction NOAEL
A Reproduction LOAEL
- Eco-SSL (mg/kg dw)
Reproduction and Growth
Figure AX7-1.3.2. Mammalian reproduction and growth toxicity data considered in
development of the Eco-SSL.
Source: U.S. Environmental Protection Agency (2005b).
wildlife generally would occur at doses greater than the 2 to 8 mg/kg-day reported to be toxic to
most animals in the 1986 Lead AQCD (U.S. Environmental Protection Agency, 1986a).
AX7.1.3.4 Recent Studies on the Effects of Lead on Decomposers
Recent studies on effects of Pb to two groups of decomposers are summarized in this
subsection. Effects on terrestrial invertebrates, such as earthworms and springtails, are described
first, followed by effects on microorganisms.
Effects on Invertebrates
Since the 1986 Lead AQCD, there have been several studies in which terrestrial
invertebrates were exposed to Pb in soil. Many of these were reviewed during the development
of the Eco-SSLs (U.S. Environmental Protection Agency, 2005b). The relevant information
from the Eco-SSL document is described below.
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A literature search and review was conducted to identify critical papers published since
2002. Effects on earthworms and other invertebrates observed in studies conducted since the
1986 Lead AQCD are similar to those reported previously: mortality and decreased growth and
reproduction (Lock and Janssen, 2002; Davies et al., 2002; Rao et al., 2003; Bongers et al., 2004;
Nursita et al., 2005; U.S. Environmental Protection Agency, 2005b).
The literature search completed for terrestrial invertebrate Eco-SSL development
identified 179 papers for detailed review, of which 13 met the minimum criteria for further
consideration (U.S. Environmental Protection Agency, 2005b). Most of the 18 ecotoxicological
endpoints that were further evaluated measured reproduction or survival as the ecologically
relevant endpoint. Four of these, representing one species under three different pH test
conditions were used to develop the Eco-SSL of 1700 mg/kg soil (Table AX7-1.3.5).
Table AX7-1.3.5. Invertebrate Toxicity Data Used to Develop the Eco-SSL
Invertebrate Species
Collembola
(Folsomia Candida)
Collembola
Collembola
Collembola
Soil pH
6.0
4.5
5.0
6.0
% Organic
Matter
10
10
10
10
Toxicity Parameter
MATC1 (reproduction)
MATC (reproduction)
MATC (reproduction)
MATC (reproduction)
Geometric Mean
Pb in Soil
(mg/kg dw)
3162
3162
894
894
1682
* MATC = Maximum Acceptable Threshold Concentration, or the geometric mean of the NOEC (no-observed-
effect concentration) and LOEC (lowest-observed-effect concentration).
Source: U.S. Environmental Protection Agency (2005b).
In a study designed to test the toxicity of Pb to the earthworm Eiseniafetida, Davies
et al. (2002) found that the 28-day LC50 (± 95% confidence intervals) for Pb in soils
contaminated with Pb(NC>3)2 was 4379 V 356 mg/kg. Twenty-eight day ECso values
(±95% confidence intervals) for weight change and cocoon production were 1408 V 198 and
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971 V 633 mg/kg, respectively. Significant mortalities were noted at concentrations of 2000
mg/kg. These data are consistent with those reported in the Eco-SSL document (U.S.
Environmental Protection Agency, 2005b) for the same species of earthworm.
Nursita et al. (2005) found no mortality and no adverse effects on reproduction (i.e.,
number of juveniles) of the collembolan Proisotoma minuta exposed for 42 days to 300, 750,
1500, or 3000 mg Pb/kg as Pb-nitrate in an acidic (pH = 4.88) sandy loam soil. It was noted that
the soils were allowed to equilibrate for 4 weeks after adding the Pb-nitrate before the organisms
were added. The observation of no effect at 3000 mg/kg is consistent with that of Sandifer and
Hopkin (1996). Sandifer and Hopkin (1996) determined a NOEC (no-observed-effect
concentration) and LOEC (lowest-observed-effect concentration) for collembolan reproduction
of 2000 and 5000 mg/kg, respectively. (A MATC [maximum-acceptable-threshold
concentration] of 3162 mg/kg was used to develop the Eco-SSL).
The remaining 14 toxicity endpoints that were not used to develop the Eco-SSL for
invertebrates are presented in Table AX7-1.3.6. None of these endpoints was considered eligible
for Eco-SSL derivation.
Lock and Janssen (2002) exposed the potworm Enchytraeus albidus to Pb, as Pb-nitrate.
The 21-day LCso was 4530 mg/kg, and the 42-day ECso for juvenile reproduction was
320 mg/kg. The Fl generation was then grown to maturity in the same concentration soil and
subsequently used in a reproduction test. The ECso for the Fl generation (394 mg/kg) was
similar to that of the P generation. The authors concluded that the two-generation assay did not
increase the sensitivity of the test (Lock and Janssen, 2002). None of the 18 toxicity endpoints
evaluated in detail during development of the Eco-SSLs used this species. The LCso reported for
the potworm was higher than reported for nematodes and similar to that reported for the
earthworm. The ECso for reproduction was lower than reported for the earthworm or collembola.
Recent work by Bongers et al. (2004) cautioned against attributing all toxicity observed in
a spiked-soil toxicity test to Pb. They found that the counterion may also contribute to the
toxicity of Pb in the springtail Folsomia Candida. This may have implications on the
interpretation of the Eco-SSL data, because the toxicity of the counterion (nitrate) was not taken
into account during Eco-SSL development. Percolation (removal of the counterion) had no
statistically significant effect on Pb-chloride toxicity (LCso = 2900 mg/kg for both non-
percolated and percolated soil; ECso for reproduction = 1900 mg/kg or 2400 mg/kg for
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Table AX7-1.3.6. Invertebrate Toxicity Data Not Used to Develop the Eco-SSL
Invertebrate Species
Nematode
Nematode
Nematode
Nematode
Nematode
Nematode
Earthworm
Earthworm
Earthworm
Earthworm
Nematode
Nematode
Nematode
Nematode
Soil pH
4
4
4
4
6.2
5.1
6.3
6.1
6.0
6.5
4
4
6.1
6.2
% Organic
Matter
1.14
1.14
4.2
4.2
1.7
3.0
10.0
10.0
10.0
10.0
10
10
3.4
2.2
Toxicity
Parameter
LCso
LCso
LC50
LC50
LCso
LCso
EC50
EC50
LCso
ILL
LC50
NOAEC
LCso
LC50
Pb in Soil
(mg/kg dw)
285
297
847
1341
1554
891
1940
1629
3716
1.16
1434
2235
13.9
11.6
*NOAEC (no-observed-adverse-effect concentration); LC50 (concentration lethal to 50% of test population);
EC50 (effect concentration for 50% of test population); ILL (incipient lethal level).
Source: U.S. Environmental Protection Agency (2005b).
non-percolated or percolated soil, respectively). However, percolation did have a significant
effect on Pb-nitrate toxicity (LCso = 980 mg/kg or 2200 mg/kg for non-percolated or percolated
soil, respectively; ECso for reproduction = 580 mg/kg or 1700 mg/kg for non-percolated or
percolated soil, respectively). Lead nitrate was more toxic than Pb-chloride for survival and
reproduction. However, the toxicity of Pb, from chloride or nitrate, was not significantly
different after the counterion was percolated out of the test soil. It is noted that the soil was left
for 3 weeks to equilibrate before testing. Lock and Janssen (2002) also found that Pb-nitrate was
more toxic than Pb-chloride, and they used Pb-nitrate in their experiments because 1000 mg/kg
Pb-chloride did not produce any mortality in their range-finding tests. This difference in
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chloride and nitrate toxicity has not been found for earthworms (Neuhauser et al., 1985; Bongers
et al., 2004).
Rao et al. (2003) exposed the earthworm Eisenia fetida to Pb-oxide in an artificial soil
with a pH of 6 at the LCso concentration of 11 mg/kg. Exposure for 14 days resulted in a number
of effects including body fragmentation, protrusions, rupture of the cuticle, etc. Many of these
effects may trigger defensive mechanisms. For example, fragmentation of the affected posterior
region was followed by regeneration and a new ectoderm layer was formed to cover affected
areas, both of which processes may serve to prevent soil bacteria from further affecting the
earthworm (Rao et al., 2003).
Effects on Microorganisms and Microbial Processes
Microorganisms and microbial processes were not included in the Eco-SSL development
process (see Attachment 1-2 of OSWER Directive 92857-55 dated November 2003 in U.S.
Environmental Protection Agency [2005a]). Many reasons were given, including that it is
unlikely that site conditions would only pose unacceptable risk to microbes and not be reflected
as unacceptable risks to higher organisms; that the significance of laboratory-derived effects data
to the ecosystem is uncertain; and that the spatial (across millimeter distances) and temporal
(within minutes to hours) variation makes understanding ecological consequences challenging.
Microbial endpoints often vary dramatically based on moisture, temperature, oxygen, and many
non-contaminant factors. Therefore, the recommendation arising from the Eco-SSL
development process was that risks to microbes or microbial processes not be addressed through
the chemical screening process but that they should be addressed within a site-specific risk
assessment (U.S. Environmental Protection Agency, 2005b).
Few studies on the effects of Pb to microbial processes have been published since 1986.
As the direct toxicity to fungi and bacterial populations are difficult to determine and interpret,
indicators for soil communities are often measured as proxies for toxicity (e.g., urease activity in
soil). Recent studies of this nature (Doelman and Haanstra, 1986; Wilke, 1989; Haanstra and
Doelman, 1991) are summarized in this subsection. The Pb concentrations in these recent
studies (1000 to 5000 mg/kg) are consistent with those reported in the 1986 Lead AQCD (U.S.
Environmental Protection Agency, 1986a) as associated with effects on microbial processes
(750 to 7500 mg/kg).
AX7-85
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The effects of Pb-chloride on the processes of nitrification and nitrogen mineralization
were studied in a 28-day experiment by Wilke (1989). The authors reported that nitrification
was increased by 12 and 16% at levels of 1000 and 4000 mg/kg, respectively, and that nitrogen
mineralization was reduced by 32 and 44% at concentrations of 1000 and 4000 mg/kg,
respectively.
The effects of Pb on arylsulfatase (Haanstra and Doelman, 1991) and urease activity
(Doelman and Haanstra, 1986) in soil were investigated. LCsoS for decreases in arylsulfatase
activity were reported at Pb concentrations of 3004 and 4538 mg/kg in a silty loam soil, at pH 6
and 8, respectively. The LCso for a decrease in urease activity was 5060 mg Pb/kg in a sandy
loam soil.
In laboratory microcosm studies Cotrufo et al. (1995) found that decomposition of oak
(Quercus ilex) leaf litter was reduced at elevated Pb (-20 mg Pb g!1 C) levels after 8 months
compared to controls (~2 mg Pb g!1 C). The researchers found soil respiration and amount of
soil mycelia correlated negatively with soil Pb, Zn and Cr concentration.
AX7.1.3.5 Summary
The current document expands upon and updates knowledge related to the effects of Pb
on terrestrial primary producers, consumers, and decomposers.
Primary Producers
The effects of Pb on terrestrial plants include decreased photosynthetic and transpiration
rates in addition to decreased growth and yield. The phytotoxicity of Pb is considered to be
relatively low, and there are few reports of phytotoxicity from Pb exposure under field
conditions. Recently, phytotoxicity data were reviewed for the development of the Eco-SSL
(U.S. Environmental Protection Agency, 2005b). Many of the toxicity data presented in the Eco-
SSL document (U.S. Environmental Protection Agency, 2005b) are lower than those discussed in
the 1986 Lead AQCD, although both documents acknowledged that toxicity is observed over a
wide range of concentrations of Pb in soil (tens to thousands of mg/kg soil). This may be due to
many factors, such as soil conditions (e.g., pH, organic matter) and differences in bioavailability
of the Pb in spiked soils perhaps due to lack of equilibration of the Pb solution with the soil after
spiking. Most phytotoxicity data continue to be developed for agricultural plant species (i.e.,
AX7-86
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vegetable and grain crops). Few data are available for trees or native herbaceous plants,
although two of the five toxicity endpoints used to develop the Eco-SSL were for trees and two
were for clover.
Consumers
Effects of Pb on avian and mammalian consumers include decreased survival,
reproduction, and growth as well as effects on development and behavior. There remain few
field effects data for consumers, except from sites with multiple contaminants, for which it is
difficult to attribute toxicity specifically to Pb. Avian and mammalian toxicity data recently
were reviewed for the development of Eco-SSLs (U.S. Environmental Protection Agency,
2005b). Many of the toxicity data presented in the Eco-SSL document (U.S. Environmental
Protection Agency, 2005b) are lower than those discussed in the 1986 Lead AQCD, although the
EPA (U.S. Environmental Protection Agency, 2005b) recognizes that toxicity is observed over a
wide range of doses (<1 to >1000 mg Pb/kg bw-day). Most toxicity data for birds have been
derived from chicken and quail studies, and most data for mammals have been derived from
laboratory rat and mouse studies. Data derived for other species would contribute to the
understanding of Pb toxicity, particularly for wildlife species with different gut physiologies.
In addition, data derived using environmentally realistic exposures, such as from Pb-
contaminated soil and food, may be recommended. Finally, data derived from inhalation
exposures, which evaluate endpoints such as survival, growth, and reproduction, would
contribute to understanding the implications of airborne releases of Pb.
Decomposers
Effects of Pb on soil invertebrates include decreased survival, growth, and reproduction.
Effects on microorganisms include changes in nitrogen mineralization and enzyme activities.
Recent data on 1986 Lead toxicity to soil invertebrates and microorganisms are consistent with
those reported in the 1986 Lead AQCD (U.S. Environmental Protection Agency, 1986a), with
toxicity generally observed at concentrations of hundreds to thousands of mg/kg soil. Studies on
microbial processes may be influenced significantly by soil parameters, and the significance of
the test results is not clear.
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Ecological Soil Screening Levels (Eco-SSLs)
Eco-SSLs are concentrations of contaminants in soils that would result in little or no
measurable effect on ecological receptors (U.S. Environmental Protection Agency, 2005a). They
were developed following rigorous scientific protocols and were subjected to two rounds of peer
review. Due to conservative modeling assumptions (e.g., metal exists in most toxic form or
highly bioavailable form, high food ingestion rate, high soil ingestion rate) which are common to
screening processes, several Eco-SSLs are derived below the average background soil
concentration for a particular contaminant.
The Eco-SSLs for terrestrial plants, birds, mammals, and soil invertebrates are 120, 11,
56, and 1700 mg Pb/kg soil, respectively.
AX7.1.4 Effects of Lead on Natural Terrestrial Ecosystems
The concept that organisms are part of larger systems that include both biotic and abiotic
components of the environment dates back to the naturalists of the Victorian era. However, the
breakthrough in what we now consider the ecosystem approach to ecology occurred in the 1950s
and 1960s when E.P. and H.T. Odum pioneered the quantitative analysis of ecosystems
(Odum, 1971). This approach encouraged the calculation of energy flows into, out of, and
within explicitly defined ecosystems. The rapid development of computer technology aided in
the growth of ecosystem ecology by allowing the development and use of increasingly complex
models for estimating fluxes that could not be directly measured.
It was not long before the quantitative analysis of ecosystems was extended to examine
the flows of nutrients and other chemical compounds. In temperate terrestrial systems, the
watershed was identified as a convenient and informative experimental unit (Bormann and
Likens, 1967). A major conceptual breakthrough in the watershed approach was that drainage
water chemistry could be used as an indicator of the "health" of the ecosystem. In a system
limited by nitrogen, for example, elevated concentrations of NO3! in drainage waters indicate that
the ecosystem is no longer making optimal use of available nutrients.
The ecosystem approach can also be used effectively in the study of trace element
biogeochemistry. Input-output budgets can be used to determine whether an ecosystem is a net
source or sink of a trace element. Changes to the input-output balance over time can be used to
assess the effects of natural or experimental changes in deposition, land use, climate, or other
AX7-88
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factors. In addition, examination of fluxes within the ecosystem (in plant uptake, soil solutions,
etc.) can be used to understand the processes that are most influential in determining the fate and
transport of the trace element.
Many published ecosystem studies include data for 1 to 3 years, the typical duration of
research grant funding or doctoral dissertation research. While these studies enrich our
understanding of terrestrial ecosystems, the most valuable studies are those that are maintained
over many years. Natural variations in climate, pests, animal migrations, and other factors can
make inferences from short-term studies misleading (Likens, 1989). To nurture long-term
research, the National Science Foundation supports a network of Long-Term Ecological
Research (LTER) sites that represent various biomes.
This section describes terrestrial ecosystem research on Pb, focusing on work done since
the 1986 Lead AQCD (U.S. Environmental Protection Agency, 1986a) and highlighting key
long-term studies. Unfortunately, there are few studies that feature long-term data on trace metal
behavior at multiple levels of organization. Therefore, this examination of the effects of Pb on
terrestrial ecosystems combines insights from long- and short-term investigations as well as
studies at scales including whole ecosystems, communities, populations, and individual species.
AX7.1.4.1 Effects of Terrestrial Ecosystem Stresses on Lead Cycling
Terrestrial ecosystems may respond to stressors in a variety of ways, including reductions
in the vigor and/or growth of vegetation, reductions in biodiversity, and effects on microbial
processes. Each of these effects may lead to the "leakage" of nutrients, especially nitrogen, in
drainage waters. The reduced vigor or growth of vegetation results in a lower uptake of nitrogen
and other nutrients from soils. Reduced biodiversity accompanied by lower total net primary
productivity for the ecosystem would also result in a lower nutrient uptake. Effects of stress in
microbial populations are less obvious. If the stress reduces microbial activity rates, then
nutrients bound in soil organic matter (e.g., organic nitrogen compounds) will likely be
mineralized at a lower rate and retained in the system. On the other hand, disturbances such as
clear-cutting, ice-storm damage, and soil freezing can result in substantial nutrient losses from
soils (Bormann et al., 1968; Likens et al., 1969; Mitchell et al., 1996; Groffman et al., 2001;
Houlton et al., 2003).
AX7-89
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Since the movement and fate of Pb in terrestrial ecosystems is strongly related to the
organic matter cycle (Section AX7.1.2), stressors that could lead to disruption or alteration of the
soil organic matter pool are of particular concern in assessing effects of ecosystem stress on Pb
cycling. By binding soluble Pb, soil organic matter acts as a barrier to the release of Pb to
drainage waters (Wang et al., 1995; Kaste et al., 2003; Watmough and Hutchinson, 2004). As a
result, concentrations of Pb in soil solutions and drainage waters tend to be low (Driscoll et al.,
1988; Wang et al., 1995; Bacon and Bain, 1995; Johnson et al., 1995a). Through decomposition
and leaching, soluble organic matter is released to solution, and with it, some Pb is also
mobilized. Wang and Benoit (1996) found that essentially all of the Pb in soil solutions in a
hardwood forest in New Hampshire was bound to dissolve organic matter (DOM). This release
of soluble Pb does not typically result in elevated surface water Pb concentrations, because
(1) organic matter has a relatively long residence time in most temperate soils (Gosz et al., 1976;
Schlesinger, 1997), so only a small fraction of the organic matter pool is dissolved at any time;
(2) DOM-Pb complexes solubilized in upper soil horizons may be precipitated or adsorbed lower
in the soil profile; (3) the DOM to which Pb is bound may be utilized by microbes, allowing the
associated Pb to bind anew to soil organic matter. Together, these factors tend to moderate the
release of Pb to surface waters in temperate terrestrial ecosystems. However, stressors or
disturbances that result in increased release of DOM from soils could result in the unanticipated
release of Pb to groundwater and/or surface waters.
Acidification
The effect of acidification on ecosystem cycling of Pb is difficult to predict. Like most
metals, the solubility of Pb increases as pH decreases (Stumm and Morgan, 1995), suggesting
that enhanced mobility of Pb should be found in ecosystems under acidification stress. However,
Pb is also strongly bound to organic matter in soils and sediments. Reductions in pH may cause
a decrease in the solubility of DOM, due to the protonation of carboxylic functional groups
(Tipping and Woof, 1990). Because of the importance of Pb complexation with organic matter,
lower DOM concentrations in soil solution resulting from acidification may offset the increased
solubility of Pb and hence decrease the mobility of the organically bound metal.
In a study of grassland and forest soils at the Rothamsted Experiment Station in England,
long-term (i.e., >100 years) soil acidification significantly increased the mobility of Pb in the soil
AX7-90
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(Blake and Goulding, 2002). However, the increased mobility was only observed in very acid
soils, those with pH of <4.5. The fraction of exchangeable Pb (extracted with 0.1 M CaCb)
increased from about 3% to 15% of the total Pb in the most acidified soils. Similarly, the
fraction of organically bound Pb increased from about 2% of total Pb in neutral soils to 12% of
total Pb in the most acidified soils. Similarly, Nouri and Reddy (1995) observed higher levels of
diethylenetriaminepentaacetic-acid-[DTPA]-extractable Pb in soils in a loblolly pine forest
treated with simulated acid rain, but only in the most acidic treatment, with simulated rain with a
pHof3.5.
Although acidification may increase the mobility of Pb in some soils, it is not clear that
this Pb is actually moving through or out of the soil profile. In an examination of running waters
in Sweden, Johansson et al. (1995) found no relationship between acidification and Pb
concentrations in drainage waters and concluded that Pb concentrations were governed by the
DOM concentration, which masked any association with acidification. In an in situ lysimeter
study, Bergkvist (1986) measured lower concentrations of Pb in soil solutions draining
experimentally acidified plots than in unacidified plots. In a laboratory study using large soil
columns, Merino and Garcia-Rodeja (1997) observed no effect of experimental acidification on
the release of Pb to soil solution. Thus, while acidification may increase the potential mobility of
Pb in soils, as indicated by increases in labile soil fractions such as exchangeable and DTPA-
extractable Pb, the actual movement of Pb in the soil is limited by DOM solubilization and
transport. It is worth noting that in all of these studies, significant effects of acidification were
observed for other trace metals (Bergkvist, 1986; Johansson et al., 1995; Merino and Garcia-
Rodeja, 1997).
Acidification may enhance Pb export to drainage water in very sandy soils, soils with
limited ability to retain organic matter. Studies in the McDonald's Branch watershed in the
New Jersey pine barrens, where soil texture is similar to beach sands, suggested little Pb
retention in the mineral soil (Swanson and Johnson, 1980; Turner et al., 1985). If acidification
results in the mobilization of Pb and organic matter into these mineral soils, then increased
streamwater Pb concentrations would likely follow.
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Land Use and Industry
Changes in land use also represent potentially significant changes in the cycling of
organic matter in terrestrial ecosystems. Conversion of pasture and croplands to woodlands
changes the nature and quantity of organic matter inputs to the soil. In temperate climates, forest
ecosystems tend to accumulate organic matter in an O horizon on the forest floor, whereas
organic matter in grasslands and agricultural fields is concentrated in an A horizon at the soil
surface. Andersen et al. (2002) compared the trace metal concentrations in arable fields in
Denmark to nearby sites that had been converted to forest land. After 34 years of afforestation,
the soils showed no significant difference in Pb concentration or fractionation, despite significant
acidification of the soils. Afforestation had no effect on the soil carbon concentration,
suggesting that land use change may have little effect on Pb cycling unless soil carbon pools are
affected.
Similarly, the introduction of industrial activity may have consequences for organic
matter cycling, and subsequently, Pb mobilization. In a rare long-term study of polluted soils,
Egli et al. (1999) studied the changes in trace metal concentrations in forest soils at a site in
western Switzerland between 1969 and 1993. The site is 3 to 6 km downwind from an aluminum
industrial plant that operated between the 1950s and 1991. In the 24-year period of study, the
site experienced significant declines in organic carbon in surface (0 to 5 cm depth) and
subsurface (30 to 35 cm) soils. In the 30 to 35 cm layer, the organic carbon concentration
declined by more than 75%. Extractable Pb (using an ammonium acetate and EDTA mixture)
declined by 35% in the same layer. The authors suggested that the Pb lost from the soil had been
organically bound. While this study indicates that loss of soil carbon can induce the mobilization
and loss of Pb from terrestrial ecosystems, it is also worth noting that the decline in soil Pb was
considerably smaller than the decline in organic carbon. This suggests that Pb mobilized during
organic matter decomposition can resorb to remaining organic matter or perhaps to alternate
binding sites (e.g., Fe and Mn oxides).
The effects of industries that emit Pb to the atmosphere are discussed in Sections
AX7.1.5.2 and AX7.1.5.3 below.
Forest harvesting represents a severe disruption of the organic matter cycle in forest
ecosystems. Litter inputs are severely reduced for several years after cutting (e.g., Hughes and
Fahey, 1994). The removal of the forest canopy results in reduced interception of precipitation,
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and, therefore, increased water flux to the soil surface. Also, until a new canopy closes, the soil
surface is exposed to increased solar radiation and higher temperatures. Together, the higher
moisture and temperature in surface soils tend to increase the rate of organic matter
decomposition. Several studies have estimated decreases of up to 40% in the organic matter
content of forest floor soils after clear-cutting (Covington, 1981; Federer, 1984; Johnson et al.,
1995b). This loss of organic matter from the forest floor could result in the mobilization of
organically complexed Pb. However, observations from clear-cut sites in the United States and
Europe indicate that forest harvesting causes little or no mobilization of Pb from forest soils.
At the Hubbard Brook Experimental Forest in New Hampshire, whole-tree harvesting, the
most intensive form of clear-cutting, resulted in very small increases in Pb concentrations in soil
solutions draining the Oa soil horizon despite substantial reductions in the organic matter mass of
that horizon (Fuller et al., 1988; Johnson et al., 1995b). These increases were associated with
similarly small increases in dissolved organic carbon (DOC) concentrations in the Oa horizon
soil water. Output of Pb from the watershed stream was unaffected by clear-cutting. Similarly,
Berthelsen and Steinnes (1995) observed small decreases in the Pb content of the Oa horizon
("H" in the European system of soil classification) in clear-cut sites in Norway, compared to
uncut reference sites. This mobilization of Pb from the Oa horizon was accompanied by an
increase in the Pb content of the upper mineral soil horizons. The Pb decline in the Oa horizon
was accompanied by a decrease in the organic matter content, leading the authors to attribute the
Pb dynamics to leaching with DOM. In a study conducted in Wales, Durand et al. (1994)
observed lower Pb outputs from a stream draining a clear-cut watershed than from where the
stream drained the upper reaches of the watershed, which were uncut. The DOC and H+ outputs
were also lower in the clear-cut area. These patterns persisted in all 5 years of the study.
Forest harvesting is a severe form of ecosystem disturbance, and, thus, it is somewhat
surprising that studies of clear-cutting have shown little or no effect on Pb mobility or loss from
forest ecosystems. Perhaps the strong complexation behavior of Pb with natural organic matter
results in the retention of Pb in forest soils. Even in cases where Pb is mobilized in forest floor
soils (Fuller et al., 1988; Berthelsen and Steinnes, 1995), there is no evidence of loss of Pb from
the ecosystem, indicating that mineral soils are efficient in capturing and retaining any Pb that is
mobilized in the forest floor. Therefore, the principal risk associated with forest harvesting is the
loss of Pb in particulate form to drainage waters through erosion. In some relatively remote
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lakes in the United Kingdom the distribution of sediment-bound trace elements (including Pb)
have been affected by forestry activities and catchment erosion (Yang and Rose, 2005). Yang
and Rose (2005) believe that more contaminated soil in-wash could increase sediment heavy
metal concentrations while less contaminated soil in-wash could dilute sediment heavy metal
levels.
Climate Change
Atmospheric Pb is not likely to contribute significantly to global climate change. Lead
compounds have relatively short residence times in the atmosphere, making it unlikely that they
will reach the stratosphere. Also, Pb compounds are not known to absorb infrared radiation and,
therefore, are unlikely to contribute to stratospheric ozone depletion or global warming.
Climate change does, however, represent a disturbance to terrestrial ecosystems.
Unfortunately, the potential linkages between climate-related stress and Pb cycling are poorly
understood. As in the previous examples, effects related to alterations in organic matter cycling
may influence Pb migration. For example, an increase in temperature leading to increased rates
of organic matter decomposition could lead to temporary increases in DOM concentrations and
smaller steady-state pools of soil organic matter. Either of these factors could result in increased
concentrations of Pb in waters draining terrestrial ecosystems.
Climate change may also affect the fluctuations of temperature and/or precipitation in
terrestrial ecosystems. For example, there is some evidence for recent increases in the frequency
of soil freezing events in the northeastern United States (Mitchell et al., 1996). Soil freezing
occurs when soils have little or no snow cover to insulate them from cold temperatures and
results in an increased release of nitrate and DOC from the O horizons of forest soils (Mitchell
et al., 1996; Fitzhugh et al., 2001). Increased DOC losses from O horizons subjected to freezing
may also increase Pb mobilization.
Increased fluctuations in precipitation may induce more frequent flooding, with
potentially significant consequences for Pb contamination of floodplain ecosystems. Soils
collected from the floodplain of the Elbe River, in Germany, contained elevated concentrations
of Pb and other trace metals (Krr|ger and Grongroft, 2003). Tissues of plants from floodplain
sites did not, however, contain higher Pb concentrations than control sites. More frequent
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or more severe flooding would likely result in increased inputs of Pb and other metals to
floodplain soils.
AX7.1.4.2 Effects of Lead Exposure on Natural Ecosystem Structure and Function
The effects of Pb exposure on natural ecosystems are confounded by the fact that Pb
exposure cannot be decoupled from other factors that may also affect the ecosystem under
consideration. Principal among these factors are other trace metals and acidic deposition.
Emissions of Pb from smelting and other industrial activities are accompanied by other trace
metals (e.g., Zn, Cu, and Cd) and sulfur dioxide (SO2) that may cause toxic effects independently
or in concert with Pb. Reductions in the use of alkyl-Pb additives in gasoline have resulted in
significant decreases in Pb deposition to natural ecosystems in the northeastern United States
(Johnson et al., 1995a). However, the period in which Pb deposition has declined (ca. 1975 to
the present) has also seen significant reductions in the acidity (i.e., increased pH) of precipitation
in the region (Likens et al., 1996; Driscoll et al., 1998). Therefore, changes in ecosystem Pb
fluxes may be the result of reduced Pb inputs and/or reduced acidity.
Experimental manipulation studies do not suffer from these confounding effects, because
Pb can be added in specific amounts, with or without other compounds. Unfortunately,
ecosystem-level manipulations involving Pb additions have not been undertaken. Therefore, we
must use observations from field studies of Pb behavior in sites exposed to various forms of Pb
pollution to assess the effects of Pb on terrestrial ecosystems. This section includes a discussion
of effects of Pb in the structure and function of terrestrial ecosystems. Effects on energy flows
(food chain effects) and biogeochemical cycling are discussed in Section AX7.1.5.3.
Sites Affected by Nearby Point Sources of Lead
Natural terrestrial ecosystems near smelters, mines, and other industrial plants have
exhibited a variety of effects related to ecosystem structure and function. These effects include
decreases in species diversity, changes in floral and faunal community composition, and
decreasing vigor of terrestrial vegetation.
All of these effects were observed in ecosystems surrounding the Anaconda smelter in
southwestern Montana, which operated between 1884 and 1980 (Galbraith et al., 1995). Soils in
affected areas around the Anaconda smelter were enriched in Pb, arsenic, copper, cadmium, and
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zinc; had very low pH; and were determined to be phytotoxic to native vegetation (Kapustka
et al., 1995). The elevated soil arsenic and metal concentrations occurred despite significantly
lower organic matter concentrations in affected soils relative to reference sites (Galbraith et al.,
1995). Line-transect measurements indicated that affected sites had an average of 6.9 species per
10-m of transect, compared to 20.3 species per 10-m in the reference areas. More than 60% of
the reference sites supported coniferous (58%) or deciduous (3%) forest communities, whereas
less than 1% of the affected sites retained functioning forest stands. Abundant dead timber and
stumps confirmed that the affected sites were once as forested as the reference sites. Affected
grassland sites were also less diverse and had higher abundances of invasive species than
reference grasslands. More than 50% of the affected sites were classified as bare ground. The
occurrence of bare ground was significantly correlated with the phytotoxicity scores derived by
Kapustka et al. (1995), indicating a link between phytotoxicity and the loss of vegetation in the
affected area.
Because of the plant community changes near the Anaconda smelter, the vertical diversity
of habitats in the affected ecosystems decreased, with only shrubs and soil remaining as viable
habitats. Galbraith et al. (1995) also used the Bureau of Land Management's habitat evaluation
procedure (HEP) to estimate habitat suitability indices (HSI) for two indicator species, marten
(Martes americand) and elk (Cervus elaphus). The HSI value ranges from 0 (poor habitat) to
1 (ideal habitat). In sites affected by the Anaconda smelter, HSI values for marten averaged 0.0,
compared to 0.5 to 0.8 for the reference sites. For elk, affected sites had an average HSI of 0.10,
compared to 0.31 at reference sites.
Similar observations were made in the area surrounding Palmerton, Pennsylvania, where
two zinc smelters operated between 1898 and 1980. Soils in the area were enriched in Cd, Zn,
Pb, and Cu, with concentrations decreasing with distance from the smelter sites (Beyer et al.,
1985; Storm et al., 1994). Smelting was determined to be the principal source of Pb in soils in
residential and undeveloped areas around Palmerton (Ketterer et al., 2001), which lies on the
north side of a gap in Blue Mountain, a ridge running roughly east-west in east-central
Pennsylvania. Much of the north-facing side of Blue Mountain within 3 km of the town is bare
ground or sparsely vegetated, whereas the surrounding natural landscape is predominantly oak
forest (Sopper, 1989; Storm et al., 1994). Biodiversity in affected areas is considerably lower
than at reference sites, a pattern attributed to emissions from the smelters (Beyer et al., 1985;
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Sopper, 1989). The history is complicated, however, by the land use history of the area.
Logging and fire in the early 20th century may also have played a role in the changes in the
terrestrial ecosystems (Jordan, 1975). Extensive logging occurred after the smelters began
operation, suggesting that some of the logging may have been salvage logging in affected areas.
Regardless, the smelter emissions appear to have inhibited the regrowth of ecosystems compared
to those in nearby unaffected areas. As in Anaconda, MT, the changes in the structure and
function of the Palmerton ecosystem changed its suitability as a habitat for fauna that would
normally inhabit the area. Storm et al. (1994) did not find amphibians or common invertebrates
in two study sites nearest to the smelters. In the larger study area, they documented elevated
concentrations of Pb, Cd, Cu, and Zn in tissues of species ranging in size from red-backed
salamanders (Pletheron cenereus) to white-tailed deer (Odocoilius virginianus).
Metal pollution around a Pb-Zn smelter near Bristol, England has not resulted in the loss
of oak woodlands within 3 km of the smelter, despite significant accumulation of Pb, Cd, Cu,
and Zn in soils and vegetation (Martin and Bullock, 1994). However, the high metal
concentrations have favored the growth of metal-tolerant species in the woodland.
The effects of Pb and other chemical emissions on terrestrial ecosystems near smelters
and other industrial sites decrease downwind from the source. Several studies using the soil
burden as an indicator have shown that much of the contamination occurs within a radius of
20 to 50 km around the emission source (Miller and McFee, 1983; Martin and Bullock, 1994;
Galbraith et al., 1995; Spurgeon and Hopkin, 1996a; see also Section AX7.1.2). For example,
the concentration of Pb in forest litter declined downwind from a Pb-Zn smelter near Bristol,
UK, from 2330 to 3050 ppm in a stand 2.9 km from the smelter to 45 to 110 ppm in a stand
23 km from the smelter (Martin and Bullock, 1994). Thus, while sites near point sources of Pb
may experience profound effects on ecosystem structure and function, the extent of those effects
is limited spatially. Elevated metal concentrations around smelters have been found to persist
despite significant reductions in emissions (Hrsak et al., 2000). Most terrestrial ecosystems are
far enough from point sources that long-range Pb transport is the primary mechanism for Pb
inputs.
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Sites Affected by Long-Range Lead Transport
Because the effects of anthropogenic Pb emissions tend to be restricted in geographic
extent, most natural terrestrial ecosystems in the U.S. sites have Pb burdens derived primarily
from long-range atmospheric transport. Pollutant Pb represents a large fraction of the Pb in
many of these ecosystems. In particular, many of these sites have accumulated large amounts of
Pb in soils. For example, at the Hubbard Brook Experimental Forest in New Hampshire, the
amount of Pb in the forest floor was estimated to have increased from about 1.35 kg ha!1 in 1926
(before the introduction of alkyl-Pb additives in gasoline) to 10.5 kg ha!1 in 1977 (Johnson et al.,
1995a). They also estimated the atmospheric Pb deposition from 1926 to 1987 to be 8.7 kg ha!1,
an amount that could account for nearly all of the increase in Pb in the forest floor during the
period. The input of precipitation Pb to the Hubbard Brook ecosystem in the six decades
spanning 1926 to 1987 was more than half of the total Pb estimated to have been released by
mineral weathering in the entire 12,000- to 14,000-year post-glacial period (14.1 kg ha!1:
[Johnson et al., 2004]). Other studies employing Pb budgets (Miller and Friedland, 1994;
Watmough et al., 2004), and Pb isotopes (Bacon et al., 1995, 1996; Watmough et al., 1998;
Bindler et al., 1999; Hansmann and Koppel, 2000; Kaste et al., 2003), have also shown that
pollutant Pb, primarily from gasoline combustion, represents a quantitatively significant fraction
of labile Pb in temperate soils, especially in the upper, organic-rich horizons.
Despite years of elevated atmospheric Pb inputs and elevated concentrations in soils, there
is little evidence that sites affected primarily by long-range Pb transport have experienced
significant effects on ecosystem structure or function. Low concentrations of Pb in soil
solutions, the result of strong complexation of Pb by soil organic matter, may explain why few
ecological effects have been observed. At Hubbard Brook, for example, the concentration of Pb
in soil solutions draining the Oa horizon is <0.1 |iM and is even lower in solutions draining
mineral-soil horizons (Driscoll et al., 1988; Wang et al., 1995). Friedland and Johnson (1985)
measured similar concentrations in soil solutions collected from deciduous and spruce-fir stands
on Camel's Hump Mountain in Vermont. In an undeveloped, forested watershed in Maryland,
Scudlark et al. (2005) found that atmospheric input of some elements (Al, Cd, Ni, Zn) is
effectively transmitted through the watershed, whereas other elements (Pb, As, Se, Fe, Cr, Cu)
are strongly sequestered, in the respective order noted.
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In ecosystems where Pb concentrations in soil solutions are low, toxicity levels for
vegetation are not likely to be reached regardless of the soil Pb concentration. Furthermore,
mycorrhizal infection of tree roots appears to reduce the translocation of Pb from roots to shoots
(Marschner et al., 1996; Jentschke et al., 1998). In a study of mycorrhizal and non-mycorrhizal
Norway spruce (Picea abies (L.) Karst), mycorrhizal infection of roots was not affected by Pb
dose. Some, but not all, species of mycorrhizae showed reductions in the amount of
extrametrical mycelium with Pb exposure but only at solution concentrations of 5 jiM, a level at
least 50 times greater than typical concentrations in forest soils. In a related study, the growth
rate of mycorrhizal fungi was unaffected at solution Pb concentrations of 1 and 10 jiM, but
decreased at 500 jiM (Marschner et al., 1999).
Low soil solution Pb concentrations and the influence of mycorrhizal symbionts also
result in low uptake of Pb by terrestrial vegetation. The net flux of Pb into vegetation in the
northern hardwood forest at Hubbard Brook in the 1980s was estimated as only 1 g ha!1 year'1
(Johnson et al., 1995a), representing 3% of the precipitation input. Klaminder et al. (2005) also
measured a Pb uptake of 1 g ha!1 year'1 in a spruce-pine forest in northern Sweden. Despite plant
uptake fluxes being very low, they are sensitive to differences and changes in Pb deposition.
Berthelsen et al. (1995) observed decreases in the Pb content of stem, twig, leaf, and needle
tissues of a variety of tree species in Norway between 1982 and 1992, when atmospheric Pb
deposition declined by approximately 70%. They also observed significantly lower Pb
concentrations in tree tissues collected in northern Norway versus southern Norway, where
atmospheric Pb deposition is greater.
Even at subtoxic concentrations, Pb and other metals may influence species diversity in
terrestrial ecosystems. However, little work has been done on the effect of low-level metal
concentrations on species diversity. In one study, plant species diversity was positively
correlated to the concentration of available Pb in natural and artificial urban meadows in Britain
(McCrea et al., 2004). The authors hypothesized that Pb may inhibit phosphorous uptake by
dominant species, allowing less abundant (but more Pb-tolerant) ones to succeed.
AX7.1.4.3 Effects of Lead on Energy Flows and Biogeochemical Cycling
In terrestrial ecosystems, energy flow is closely linked to the carbon cycle. The principal
input of energy to terrestrial ecosystems is through photosynthesis, in which CC>2 is converted to
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biomass carbon. Because of this link between photosynthesis and energy flow, any effect that Pb
has on the structure and function of terrestrial ecosystems (as discussed in Section AX7.1.5.3.)
influences the flow of energy into the ecosystem. This section focuses on how Pb influences
energy transfer within terrestrial ecosystems, which begin with the decomposition of litter and
other detrital material by soil bacteria and fungi, and cascade through the various components of
the detrital food web. Because the mobility of Pb in soils is closely tied to organic matter
cycling, decomposition processes are central to the biogeochemical cycle of Pb. This section
concludes with a discussion of how biogeochemical cycling of Pb has changed in response to the
changing Pb inputs to terrestrial ecosystems.
Effects of Lead on Detrital Energy Flows
Lead can have a significant effect on energy flows in terrestrial ecosystems. At some sites
severely affected by metal pollution, death of vegetation can occur, dramatically reducing the
input of carbon to the ecosystem (Jordan, 1975; Galbraith et al., 1995). Subsequently, wind and
erosion may remove litter and humus, leaving bare mineral soil, a nearly sterile environment in
which very little energy transfer can take place (Little and Martin, 1972; Galbraith et al., 1995).
At Pb-affected sites that can retain a functioning forest stand, the rate of decomposition of
litter may be reduced, resulting in greater accumulation of litter on the forest floor than in
unpolluted stands. Numerous investigators have documented significant declines in litter
decomposition rates (Cotrufo et al., 1995; Johnson and Hale, 2004) and/or the rate of carbon
respiration (Laskowski et al., 1994; Cotrufo et al., 1995; Saviozzi et al., 1997; Niklinska et al.,
1998; Palmborg et al., 1998; Aka and Darici, 2004) in acid- and metal-contaminated soils or soils
treated with Pb. The resulting accumulation of organic matter on the soil surface can be
dramatic. For example, an oak woodland 3 km from a smelter in Bristol, England had a litter
layer mass 10 times greater than the mass in a similar stand 23 km from the smelter (Martin and
Bullock, 1994).
Reduced decomposition rates in polluted ecosystems are the result of the inhibition of soil
bacteria and fungi and its effects on microbial community structure (Baath, 1989). Kuperman
and Carreiro (1997) observed 60% lower substrate-induced respiration in heavily polluted
grassland soils near the U.S. Army's Aberdeen Proving Ground in Maryland. This decline in
carbon respiration was associated with 81% lower bacterial biomass and 93% lower fungal
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biomass. Similar declines in the activities of carbon-, nitrogen-, and phosphorus-acquiring
enzymes were also observed. Such dramatic effects have only been observed in highly
contaminated ecosystems. In a less contaminated grassland site near a Pb factory in Germany,
Chander et al. (2001) observed a lower ratio of microbial biomass carbon to soil organic carbon
in polluted soils. The ratio of basal respiration to microbial biomass (the "metabolic quotient,"
qCC>2) declined with increasing metal concentration, though this observation depended on the
procedure for measuring microbial biomass (substrate-induced respiration versus fumigation-
extraction). The combined effect of lower microbial biomass per unit soil carbon and similar or
lower qCC>2 on polluted sites indicates that the ability of soil microorganisms to process carbon
inputs is compromised by metal pollution.
The type of ecosystem also plays a role in determining the effects of Pb and other metals
on the microbial processing of litter. Forest soils in temperate zones accumulate organic matter
at the soil surface to a greater degree than in grasslands. This organic-rich O horizon can support
a large microbial biomass; but it is also an effective trap for Pb inputs, because of the association
between Pb and soil organic matter. At highly contaminated forest sites, microbial biomass and
enzyme activities may be depressed (Fritze et al., 1989; Baath et al., 1991), causing slower
decomposition of the litter.
In addition to effects on decomposition and carbon transformations, Pb and other trace
metals can also influence key nitrogen cycling processes. Studies in the 1970s demonstrated that
Pb and other metals inhibit the mineralization of nitrogen from soil organic matter and
nitrification (Liang and Tabatabai, 1977, 1978), resulting in lower nitrogen availability to plants.
More recent research has documented significant inhibitory effects of Pb and other metals on the
activities of several enzymes believed to be crucial to nitrogen mineralization in soils (Senwo
and Tabatabai, 1999; Acosta-Martinez and Tabatabai, 2000; Ekenler and Tabatabai, 2002). This
suggests that the inhibitory effect of Pb and other metals is broad-based, and not specific to any
particular metabolic pathway. In reducing environments, the rate of denitrification is also
depressed by trace metals. Fu and Tabatabai (1989) found that 2.5 jimol g!1 of Pb (ca.
500 mg/kg!1) was sufficient to cause 0, 27, and 52% decreases in nitrogen reductase activity in
three different soils.
Metal pollution can also affect soil invertebrate populations. Martin and Bullock (1994)
observed lower abundances of a variety of woodlice, millipedes, spiders, insects, and earthworms
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in an oak woodland site 3 km from a Pb-Zn smelter in Bristol, England, compared to a reference
site 23 km from the smelter. The differences were most dramatic when expressed per unit mass
of litter. Several species that were abundant in the reference site were not found in the
contaminated woodland. For example, the abundance of the woodlice Trichoniscus pusillus
was 151 individuals per m2 in the reference woodland, but none were found in the contaminated
soils. This was also true of 2 of the 3 millipede species, and 4 of the 5 earthworm species
studied. At six sites within 1 km from the smelters, no earthworms were present at all (Spurgeon
and Hopkin, 1996a). Contamination at this site has apparently reduced both the population and
biodiversity of the soil invertebrate community.
The effect of metal pollution on soil invertebrates may be a threshold-type response. In a
study conducted in woodlands near two zinc smelters in Noyelles-Godault, in northern France,
soils at the most polluted site were devoid of mites and millipedes, while the remaining sites had
diversity measures similar to control sites (Grelle et al., 2000).
While Pb pollution affects the population and diversity of soil fauna, there is little
evidence of significant bioaccumulation of Pb in the soil food web (see also Section AX7.1.3).
In the Bristol, England study, Pb concentrations in earthworms were lower than soil Pb
concentrations and much lower than litter Pb concentrations (Martin and Bullock, 1994). Litter-
dwelling mites had Pb concentrations that were 10% of the average litter concentration. The
predator centipedes Lithobius forficatus and L. variegatus had mean Pb concentrations of
18.6 and 44.0 mg kg'1, respectively, two orders of magnitude lower than the Pb concentration of
litter (2193 mg kg'1) and lower than the concentrations of their known prey species. In a study
conducted in a Norway spruce forest affected primarily by automobile exhaust from a nearby
highway, earthworms had Pb concentrations similar to the soil (Roth, 1993). Almost all of the
litter decomposers, however, had Pb concentrations that were less than 20% of the litter. All but
3 of the zoophagous arthropods had Pb concentrations that were less than 40% of their prey; the
remaining 3 had Pb concentrations similar to their prey. Because of the absence of significant
bioaccumulation in the soil food web, predator species will be affected by Pb pollution primarily
through effects on the abundance of their prey (Spurgeon and Hopkin, 1996b).
Taken as a whole, ecosystem-level studies of the soil food web indicate that Pb can affect
energy flows in terrestrial ecosystems through two principal mechanisms. In the most severely
polluted sites, the death of primary producers directly decreases the flow of energy into the
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ecosystems. More commonly, the accumulation of toxic levels of Pb or other metals in litter and
soil decreases the rate of litter decomposition through decreases in microbial biomass and/or
respiration. These reductions can subsequently affect higher trophic levels that depend on these
organisms. It is important to note that sites that have exhibited significant disruption to energy
flows and the terrestrial food web are sites that have experienced severe metal contamination and
adverse effects from SC>2 from smelters or other metals-related activities.
Lead Dynamics in Terrestrial Ecosystems
Lead inputs to terrestrial ecosystems in the United States have declined dramatically in the
past 30 years, primarily because of the almost complete elimination of alkyl-Pb additives in
gasoline in North America. Also, Pb emissions from smelters have declined as older plants have
been shut down or fitted with improved emissions controls. Unfortunately, there are few long-
term data sets of precipitation inputs to terrestrial ecosystems. At the Hubbard Brook
Experimental Forest, in New Hampshire, Pb input in bulk deposition declined by more than 97%
between 1976 and 1989 (Johnson et al., 1995a). Studies of freshwater sediments also indicate a
dramatic decline in Pb inputs since the mid-1970s (Graney et al., 1995; Johnson et al., 1995a;
Farmer et al., 1997; Brannvall et al., 2001a,b).
Reported concentrations of Pb in waters draining natural terrestrial ecosystems have
always been low (Wang et al., 1995; Bacon and Bain, 1995; Johnson et al., 1995a; Vinogradoff
et al., 2005), generally less than 1 ng L!1, even at moderately polluted sites (Laskowski et al.,
1995). Consequently, most terrestrial ecosystems in North America and Europe remain sinks for
Pb despite reductions in atmospheric Pb deposition of more than 95%. At Hubbard Brook, for
example, the input of Pb in bulk precipitation declined from 325 g ha!1 year'1 between 1975 and
1977 compared to 29 g ha!1 year'1 between 1985 and 1987 (Johnson et al., 1995a). During the
same period, the output of Pb in stream water declined from 6 g ha!1 year'1 to 4 g ha'1 year'1.
Thus, despite the decline in Pb input, 85% of the incoming Pb was still retained in the terrestrial
ecosystem in the later time period. Similar observations have been made in Europe, where the
use of leaded gasoline has also declined in the last few decades. At the Glensaugh Research
Station in Scotland, the input of Pb to the forest ecosystem was estimated as 42.6 g ha'1 year'1
between 2001 and 2003, about six times the stream export of 7.2 g ha'1 year'1 (Vinogradoff et al.,
2005). Similarly, Huang and Matzner (2004) reported a throughfall flux of 16.5 g ha'1 year'1 at
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the forested Lehstenbach catchment in Bavaria, about six times the efflux in runoff of 2.82 g ha
year'1.
Lead pollution has resulted in the accumulation of large Pb burdens in terrestrial
ecosystems (see also Section AX7.1.2). Despite reductions in emissions, this accumulation of Pb
continues, though at markedly lower rates. The large pool of Pb bound in soils may potentially
be a threat to aquatic ecosystems (see Section AX7.2), depending on its rate of release from the
soil. Early estimates of the residence time of Pb in the forest floor ranged from 220 to 5,000
years (Benninger et al., 1975; Friedland and Johnson, 1985; Turner et al., 1985). However, more
recent literature suggests that Pb is transported more rapidly within soil profiles than previously
believed. The pool of Pb in forest floor soils of the northeastern United States declined
significantly in the late 20th century. Friedland et al. (1992) reported a 12% decline in the
amount of Pb in forest floor soils at 30 sites in the region between 1980 and 1990, a much greater
decline than would be expected for a pool with a residence time of 220 to 5,000 years.
At Hubbard Brook, the pool of Pb in the forest floor declined by 29% between 1977 and 1987,
an even more rapid rate of loss than reported by Friedland et al. (1992). More recently, Evans
et al. (2005) reported significant declines in the Pb content of forest floor soils in the
northeastern United States and eastern Canada between 1979 and 1996. The magnitude of the
decrease in Pb content was greatest at their sites in southern Vermont, and smallest at sites on the
Gaspe Peninsula in Quebec, reflecting the historic gradient in Pb deposition in the region. At the
Vermont site, the Pb concentration in the litter layer (Oi horizon) was 85% lower in 1996 than in
1979. In the Gaspe peninsula of Quebec, the decrease was only 50%.
Since drainage water Pb concentrations remain low, the Pb released from forest floor soils
in the past has been largely immobilized in mineral soils (Miller and Friedland, 1994; Johnson
et al., 1995a; Johnson and Petras, 1998; Watmough and Hutchinson, 2004; Johnson et al., 2004).
This is supported by evidence from Pb-isotope analyses. Gasoline-derived Pb has a 206Pb:207Pb
ratio that can be easily discriminated from Pb in the rocks from which soils are derived. Using
isotopic mixing models with gasoline-Pb and Pb in soil parent materials as end members,
a number of researchers have documented the accumulation of pollutant Pb in mineral soils
(Bindler et al., 1999; Kaste et al., 2003; Watmough and Hutchinson, 2004; Bacon and Hewitt,
2005; Steinnes and Friedland, 2005). In a hardwood stand on Camel's Hump Mountain in
Vermont, as much as 65% of the pollutant Pb deposited to the stand had moved into mineral
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horizons by 2001 (Kaste et al., 2003). In a spruce-fir stand, containing a thicker organic forest
floor layer, penetration of pollutant Pb into the mineral soil was much lower.
This recent research has resulted in a reevaluation of the turnover time of Pb in forest
floor soils. The Camel's Hump data suggest that Pb resides in the forest floor of deciduous
stands for about 60 years and about 150 years in coniferous stands (Kaste et al., 2003). These
values are somewhat greater than those published previously by Miller and Friedland (1994),
who used a Pb budget approach. Extremely rapid turnover of Pb was observed in some
hardwood forest floor soils in south-central Ontario (Watmough et al., 2004). Their estimated
turnover times of 1.8 to 3.1 years are much lower than any other published values, which they
attribute to the mull-type forest floor at their sites. Mull-type forest floors are normally underlain
by organic-rich A horizons, capable of immobilizing Pb released from the forest floor. Indeed,
at the same site in Ontario, Watmough and Hutchinson (2004) found that 90% of the pollutant Pb
could be found in this A horizon.
The time period over which the accumulated Pb in soils may be released to drainage
waters remains unclear. If Pb moves as a pulse through the soil, there may be a point in the
future at which problematic Pb concentrations occur. However, several authors have argued
against this hypothesis (Wang and Benoit, 1997; Kaste et al., 2003; Watmough et al., 2004),
contending that the strong linkage between Pb and DOM will result in a temporally dispersed
release of Pb in the form of Pb-DOM complexes. Thus, the greatest threat is likely to be in the
most highly contaminated areas surrounding point sources of Pb, where the amount of Pb
accumulated in the soil is high, and the death of vegetation has resulted in reduced soil organic
matter levels.
AX7.1.4.4 Summary
Atmospheric Pb pollution has resulted in the accumulation of Pb in terrestrial ecosystems
throughout the world. In the United States, pollutant Pb represents a significant fraction of the
total Pb burden in soils, even in sites remote from smelters and other industrial plants. However,
few significant effects of Pb pollution have been observed at sites that are not near point sources
of Pb. Evidence from precipitation collection and sediment analyses indicates that atmospheric
deposition of Pb has declined dramatically (>95%) at sites unaffected by point sources of Pb, and
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there is little evidence that Pb accumulated in soils at these sites represents a threat to
groundwaters or surface water supplies.
The highest environmental risk for Pb in terrestrial ecosystems exists at sites within about
50 km of smelters and other Pb-emitting industrial sites. Assessing the risks specifically
associated with Pb is difficult, because these sites also experience elevated concentrations of
other metals and because of effects related to SC>2 emissions. The concentrations of Pb in soils,
vegetation, and fauna at these sites can be two to three orders of magnitude higher than in
reference areas (see Sections AX7.1.2 and AX7.1.4.2). In the most extreme cases, near smelter
sites, the death of vegetation causes a near-complete collapse of the detrital food web, creating a
terrestrial ecosystem in which energy and nutrient flows are minimal. More commonly, stress in
soil microorganisms and detritivores can cause reductions in the rate of decomposition of detrital
organic matter. Although there is little evidence of significant bioaccumulation of Pb in natural
terrestrial ecosystems, reductions in microbial and detritivorous populations can affect the
success of their predators. Thus, at present, industrial point sources represent the greatest Pb-
related threat to the maintenance of sustainable, healthy, diverse, and high-functioning terrestrial
ecosystems in the United States.
AX7.2 AQUATIC ECOSYSTEMS
AX7.2.1 Methodologies Used in Aquatic Ecosystem Research
As discussed in previous sections, aerial deposition is one source of Pb deposition to
aquatic systems. Consequently, to develop air quality criteria for Pb, consideration must be
given to not only the environmental fate of Pb, but also to the environmental effects of Pb in the
aquatic environment through consideration of laboratory toxicity studies and field evaluations.
Perhaps the most straightforward approach for evaluating the effects of Pb is to consider extant
criteria for Pb in aquatic ecosystems, i.e., water and sediment quality criteria. A key issue in
developing Pb water and sediment criteria that are broadly applicable to a range of water bodies
is properly accounting for Pb bioavailability and the range in species sensitivities. This section
summarizes how these criteria are derived, the types of toxicity studies considered, and key
factors that influence the bioavailability of Pb in surface water and sediment to aquatic life.
Because Pb in the aquatic environment is often associated with other metals (e.g., cadmium,
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copper, zinc), the importance of considering the toxicity of metal mixtures is also discussed.
Finally, some issues related to background Pb concentrations are briefly addressed. It is beyond
the scope of this section to review all methodologies in aquatic system research, but good
reviews can be found in summary books, such as Rand et al. (1995).
AX7.2.1.1 Analytical Methods
Common analytical methods for measuring Pb in the aquatic environment are summarized
in Table AX7-2.1.1. For relevance to the ambient water quality criteria (AWQC) and sediment
quality criteria for Pb discussed below, minimum detection limits should be in the low parts per
billion (ppb) range for surface water and the low parts per million (ppm) range for sediment.
Table AX7-2.1.1. Common Analytical Methods for Measuring Lead in Water,
Sediment, and Tissue
Analysis Type Analytical Method
Direct-Aspiration (Flame) Atomic Absorption Spectroscopy EPA SW-846 Method 7420a,
(AAS) EPA Method 239. lb,
Standard Method 31 llc
Graphite Furnace Atomic Absorption Spectroscopy EPA SW-846 Method 7421a,
(GFAAS) EPA Method 239.2b,
Standard Method 3113C
Inductively Coupled Plasma EPA SW-846 Method 6010Ba,
(ICP) EPA Method 200.7b,
Standard Method 3120C
Inductively Coupled Plasma-Mass Spectrometry EPA SW-846 Method 6020a,
(ICP-MS) EPA Method 200.8b
a U.S. Environmental Protection Agency (1986c) Test Methods for Evaluating Solid Waste, Physical/Chemical
Methods (SW-846). Third Edition, September 1986; Final Updates I (7/92), IIA (8/93), II (9/94), IIB (1/95),
III (12/96), IIIA (4/98), IIIB (11/04).
b U.S. Environmental Protection Agency (1991) Methods for the Determination of Metals in Environmental
Samples. EPA/600/4-91-010. June 1991 (Supplement I, EPA/600/R-94-111, May 1994).
0 American Public Health Association (1995) Standard Methods for the Examination of Water and Wastewater,
19th Edition. American Public Health Association, American Water Works Association, Water Pollution
Control Federation.
In addition to the methods presented in Table AX7-2.1.1, many of the methods discussed
in Section AX7.1.1 can be applied to suspended solids and sediments collected from aquatic
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ecosystems. Just as in the terrestrial environment, the speciation of Pb and other trace metals in
natural freshwaters and seawater plays a crucial role in determining their reactivity, mobility,
bioavailability, and toxicity. Many of the same speciation techniques employed for the
speciation of Pb in terrestrial ecosystems (see Section AX7.1.1 and AX7.1.2) are applicable in
aquatic ecosystems.
There is now a better understanding of the potential effects of sampling, sample handling,
and sample preparation on aqueous-phase metal speciation. Thus, a need has arisen for dynamic
analytical techniques that are able to capture a metal's speciation, in-situ and in real time. Some
of these recently developed dynamic trace metal speciation techniques include:
• Diffusion gradients in thin-film gels (DGT)
• Gel integrated microelectrodes combined with voltammetric in situ profiling
(GIME-VIP)
• Stripping chronopotentiometry (SCP)
• Flow-through and hollow fiber permeation liquid membranes (FTPLM and FIFPLM)
• Donnan membrane technique (DMT)
• Competitive ligand-exchange/stripping voltammetry (CLE-SV)
Various dynamic speciation techniques were compared in a study by Sigg et al. (2006) using
freshwaters collected in Switzerland. They found that techniques involving in-situ measurement
(GIME-VIP) or in-situ exposure (DGT, DMT, and HFPLM) appeared to the most appropriate for
avoiding Pb and other trace metal speciation artifacts associated sampling and sample handling.
AX7.2.1.2 Ambient Water Quality Criteria: Development
The EPA's procedures for deriving AWQC are described in Stephan et al. (1985) and are
summarized here. With few exceptions, AWQC are derived based on data from aquatic toxicity
studies conducted in the laboratory. In general, both acute (short term) and chronic (long term)
AWQC are developed. Depending on the species, the toxicity studies considered for developing
acute criteria range in length from 48 to 96 hours. Acceptable endpoints for acute AWQC
development are mortality and/or immobilization, expressed as the median lethal concentration
(LCso) or median effect concentration (ECso). For each species, the geometric mean of the
acceptable LCso/ECso data is calculated to determine the species mean acute value (SMAV).
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For each genera, the geometric mean of the relevant SMAVs is then calculated to determine the
genus mean acute value (GMAV). The GMAVs are then ranked from high to low, and the final
acute value (FAV; the 5th percentile of the GMAVs, based on the four GMAVs surrounding the
5th percentile) is determined. Because the FAV is based on LCso/ECso values (which represent
unacceptably high levels of effect), the FAV is divided by two to estimate a low-effect level.
This value is then termed the acute criterion, or criterion maximum concentration (CMC). Based
on the most recent AWQC document for Pb (U.S. Environmental Protection Agency, 1985),
Table AX7-2.1.2 shows the freshwater SMAVs and GMAVs for Pb, and the resulting freshwater
CMC. Note that the freshwater AWQC are normalized for the hardness of the site water, as
discussed further below in Section AX7.2.1.3.
Table AX7-2.1.2. Development of Current Acute Freshwater Criteria for Lead
(U.S. Environmental Protection Agency, 1985)1
Rank
10
9
8
7
6
5
4
3
2
1
Species
Midge (Tanytarsus dissimilis)
Goldfish (Carassius auratus)
Guppy (Poecilia reticulatd)
Bluegill (Lepomis macrochirus)
Fathead minnow (Pimephales promelas)
Brook trout (Salvelinus fontinalis)
Rainbow trout (Oncorhynchus mykiss)
Snail (Aplexa hypnomm)
Cladoceran (Daphnia magna)
Amphipod (Gammams pseudolimnaeus)
GMAV
235,900
101,100
66,140
52,310
25,440
4,820
2,448
1,040
447.8
142.6
FAV = 67.54
CMC = 33.77
SMAV
235,900
101,100
66,140
52,310
25,440
4,820
2,448
1,040
447.8
142.6
Hg/L
^g/L
All values are normalized to a hardness of 50 mg/L (see Section AX7.2.1.3).
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To develop chronic AWQC, acceptable chronic toxicity studies should encompass the full
life cycle of the test organism, although for fish, early life stage or partial life cycle toxicity
studies are considered acceptable. Acceptable endpoints include reproduction, growth and
development, and survival, with the effect levels expressed as the chronic value, which is the
geometric mean of the no-observed-effect concentration (NOEC)1 and the lowest-observed-
effect concentration (LOEC)2. Although a chronic criterion could be calculated as the 5th
percentile of genus mean chronic values (GMCVs), sufficient chronic toxicity data are generally
lacking, as is the case for Pb. Consequently, an acute-chronic ratio (ACR) is typically applied to
the FAV to derive the chronic criterion. As the name implies, the ACR is the ratio of the acute
LCso to the chronic value, based on studies with the same species and in the same dilution water.
For Pb, the final ACR is 51.29, which results in a final chronic value (FCV) of 1.317 |ig/L (at a
hardness of 50 mg/L). The U.S. EPA guidelines for developing AWQC (Stephan et al., 1985) are
now more than 20 years old and thus are not reflective of scientific advances in aquatic
toxicology and risk assessment that have developed since the 1980s. For example, the
toxicological importance of dietary metals has been increasingly recognized and approaches for
incorporating dietary metals into regulatory criteria are being evaluated (Meyer et al., 2005).
Other issues include consideration of certain sublethal endpoints that are currently not directly
incorporated into AWQC development (e.g., endocrine toxicity, behavioral responses) and
protection of threatened and endangered (T&E) species (U.S. Environmental Protection Agency,
2003). In deriving appropriate and scientifically defensible air quality criteria for Pb, it will be
important that the state-of-the-science for metals toxicity in aquatic systems be incorporated into
the development process.
Subsequent sections summarize some of the toxicity studies that meet the AWQC
development guidelines, with an emphasis on key studies published since the last Pb AWQC
were derived in 1984.
1 The NOEC is the highest concentration tested that did not result in statistically significant effects relative
to the control.
2 The LOEC is the lowest concentration tested that resulted in statistically significant effects relative to
the control.
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AX7.2.1.3 Ambient Water Quality Criteria: Unavailability Issues
In surface waters, the environmental fate of metal contaminants is mitigated through
adsorption, complexation, chelation, and other processes that affect bioavailability. The toxicity
of divalent cations tends to be highest in soft waters with low concentrations of dissolved organic
matter and suspended particles. In an acidic environment (pH <4), the ionic form of most metals
generally predominates and is considered to be the more toxic form. As the pH increases,
carbonate, oxide, hydroxide, and sulfide complexes of the metals tend to predominate, and tend
to be less toxic (Florence, 1977; Miller and Mackay, 1980). The portion of dissolved metal
available for uptake or bioaccumulation is influenced by modifying factors that "sequester" the
metal in an environmental matrix, thereby reducing the bioavailability of the metal at the sites of
action. Metals can become complexed (bound) to a ligand that can make metals either more
toxic (via transport mechanisms) or less toxic (by changing the metal's biological activity).
Metals that complex tightly to ligands generally are not readily bioavailable and, thus, are less
toxic to aquatic biota than their free-metal ion counterparts (Carlson et al., 1986; McCarthy,
1989). There are many kinds of ligands, organic and inorganic, as well as natural and man-
made. Ligands found in natural surface waters and municipal and industrial effluent discharges
include glycine, ammonia, oxalate, humic or fulvic acids, hydroxide, carbonate, bicarbonate,
chloride, and hydrogen sulfide (Stumm and Morgan, 1970; Martin, 1986; Pagenkopf, 1986).
Recognizing the importance of calcium and magnesium ions (hardness) in modifying Pb
toxicity, the current freshwater AWQC for Pb are normalized based on the hardness of the site
water. The acute freshwater criteria, for example, are 30, 65, and 136 |ig/L at hardness levels of
50, 100, and 200 mg/L (as CaCOs). Although it has been known for some time that other water
quality parameters such as pH, dissolved organic carbon (DOC), and alkalinity affect the
bioavailability of metals to aquatic biota, it was the relatively recent development of the biotic
ligand model (BLM) that allows for AWQC to potentially consider all of these factors. Paquin
et al. (2002) provided a thorough review of the factors influencing metal bioavailability and how
research over the last few decades has culminated in the development of the BLM.
By understanding the binding affinities of various natural ligands in surface waters and
how the freshwater fish gill interacts with free cations in the water, one can predict how metals
exert their toxic effects (Schwartz et al., 2004). Models developed prior to the BLM are the free-
ion activity model (FIAM) and the gill surface interaction model (GSIM). The FIAM accounts
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for the binding of free-metal ion and other metal complexes to the site of toxic action in an
organism; and it also considers competition between metal species and other cations (Paquin
et al., 2002). The GSIM is fundamentally similar to the FIAM in that it accounts for competition
between metal ions and hardness cations at the physiological active gill sites, but whereas the
FIAM is largely conceptual, the GSIM was used in interpreting toxicity test results for individual
metals and metal mixtures (Pagenkopf, 1983). The BLM was adapted from the GSIM and uses
the biotic ligand, rather than the fish gill as the site of toxic action (Di Toro et al., 2001; Paquin
et al., 2002). This approach, therefore, considers that the external fish gill surface contains
receptor sites for metal binding (Schwartz et al., 2004) and that acute toxicity is associated with
the binding of metals to defined sites (biotic ligands) on or within the organism (Paquin et al.,
2002). The model is predicated on the theory that mortality (or other toxic effects) occurs when
the concentration of metal bound to biotic ligand exceeds a threshold concentration (Di Toro
et al., 2001; Paquin et al., 2002). Free metal cations "out compete" other cations and bind to the
limited number of active receptor sites on the gill surface, which may ultimately result in
suffocation and/or disruption of ionoregulatory mechanisms in the fish, leading to death (Di Toro
et al., 2001; Paquin et al., 2002). Because the BLM uses the biotic ligand (not the fish gill) as
the site of action, the model can be applied to other aquatic organisms, such as crustaceans,
where the site of action is directly exposed to the aqueous environment (Di Toro et al., 2001).
Although the BLM is currently being considered as a tool for regulating metals on a site-
specific basis, there are potential limitations in using the BLM to regulate metals in surface
waters that should be understood in developing air quality criteria for lead. For example, BLMs
developed to-date have focused on acute mortality/immobilization endpoints for fish and
invertebrates. Chronic exposures are typically of greatest regulatory concern, but chronic BLMs
to date have received limited attention (De Schamphelaere and Janssen, 2004). In addition,
BLMs account for uptake of dissolved metal, but dietary metals have also been shown to
contribute to uptake by aquatic biota and, in some cases, increased toxicity. Besser et al. (2005)
observed that chronic (42-day) Pb toxicity to the amphipod Hyalella azteca was greater from a
combined aqueous and dietary exposure than from a water-only exposure and the authors
conclude that estimates of chronic toxicity thresholds for Pb should consider both aqueous and
dietary exposure routes. The feasibility of incorporating dietary metals into BLMs is under
investigation. Another important issue that must be addressed in developing and applying a
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BLM in AWQC development is the type of dissolved organic matter used in model development
relative to the types of dissolved organic matter at the site of interest. Richards et al. (2001)
demonstrated that natural organic matter (NOM) of different types differentially influenced Pb
and Cu accumulation by gills of rainbow trout. There are also other ligands not accounted for in
the BLM that require more research. Bianchini and Bowles (2002) emphasized the importance
of reduced sulfur as a metal ligand, limitations in scientific knowledge on reduced sulfur, and
provided recommendations for studies necessary to incorporate sulfide ligands into the BLM.
The U.S. EPA is currently revising the aquatic life AWQC for lead, which will include
toxicity data published after the 1985 AWQC were released and incorporation of the BLM is
being evaluated. If an acute BLM is incorporated into the revised AWQC for lead, the chronic
criteria would likely be estimated using an ACR (the same approach used when the acute
criterion is based on empirical toxicity data; see above).
AX7.2.1.4 Sediment Quality Criteria: Development and Unavailability Issues
As with metals in surface waters, the environmental fate of metal contaminants in
sediments is moderated through various binding processes that reduce the concentration of free,
bioavailable metal. Sediments function as a sink for Pb, as with most metals. Lead compounds
such as Pb-carbonates, Pb-sulfates, and Pb-sulfides predominate in sediments (Prosi, 1989).
Total Pb has a higher retention time and a higher percentage is retained in sediments compared to
copper and zinc (Prosi, 1989). Lead is primarily accumulated in sediments as insoluble Pb
complexes adsorbed to suspended particulate matter. Naturally occurring Pb is bound in
sediments and has a low geochemical mobility (Prosi, 1989). Organic-sulfide and moderately
reducible fractions are less mobile, whereas cation-exchangeable fractions and easily-reducible
fractions are more mobile and more readily bioavailable to biota (Prosi, 1989). Most Pb
transported in surface waters is in a particulate form, originating from the erosion of sediments in
rivers or produced in the water column (Prosi, 1989).
Sediment quality criteria have yet to be adopted by the EPA, but an equilibrium
partitioning procedure has recently been published (U.S. Environmental Protection Agency,
2005c). The EPA has selected an equilibrium partitioning approach because it explicitly
accounts for the bioavailability of metals. This approach is based on mixtures of cadmium,
copper, Pb, nickel, silver, and zinc. Equilibrium partitioning (EqP) theory predicts that metals
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partition in sediment between acid-volatile sulfide, pore water, benthic organisms, and other
sediment phases such as organic carbon. When the sum of the molar concentrations of
simultaneously extracted metal (ZSEM) minus the molar concentration of AVS is less than zero,
it can accurately be predicted that sediments are not toxic because of these metals. Note that this
approach can be used to predict the lack of toxicity, but not the presence of toxicity. It is
important to emphasize that metals must be evaluated as a mixture using this approach.
If individual metals, or just two or three metals, are measured in sediment, ZSEM would be
misleadingly small and it may inaccurately appear that ZSEM / AVS is less than 1.0.
If ZSEM / AVS is normalized to the organic carbon fraction (i.e., (ZSEM / AVS)//OC),
mortality can be more reliably predicted by accounting for both the site-specific organic carbon
and AVS concentrations. When evaluating a metal mixture containing cadmium, copper, Pb,
nickel, silver, and zinc, the following predictions can be made (U.S. Environmental Protection
Agency, 2005c):
• A sediment with (SEM / AVS)//bc < 130 jimol/goc should pose low risk of adverse
biological effects due to these metals.
• A sediment with 130 jimol/goc < (SEM / AVS)//bc< 3000 jimol/goc may have adverse
biological effects due to these metals.
• In a sediment with (SEM / AVS)//bc > 3000 jimol/goc, adverse biological effects may
be expected.
A third approach is to measure pore water concentrations of cadmium, copper, Pb, nickel,
and zinc and then divide the concentrations by their respective FCVs. If the sum of these
quotients is <1.0, these metals are not expected to be toxic to benthic organisms.
It should be noted that although EPA has endorsed the AVS-SEM approach for
developing sediment guidelines, other investigators do not necessarily agree, as the AVS-SEM
approach may not be relevant to benthic organisms that ingest sediment particles. For example,
Griscom et al. (2002) found that metals associated with either reduced or oxidized sediment
particles can be assimilated by deposit and suspension feeding bivalve species due to the low pH
and moderate reducing conditions in bivalve guts. Although Lee et al. (2000) agreed that the
AVS-based approach may be appropriate for protecting some benthic organisms from acute
toxicity associated with exposure to very high pore water concentrations of metals, they
questioned whether the AVS-based approach is relevant to less contaminated sediments under
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more natural conditions with vertical stratification of oxygen concentrations and, hence, varying
levels of AVS. The authors concluded that important uncertainties remain in the application of
the AVS-SEM approach as a regulatory tool. Similarly, some studies suggest that AVS-SEM
measurements in the natural environment must be interpreted cautiously as AVS can be quite
variable with sediment depth and season (Van den Berg et al., 1998). Finally, Long et al. (1998)
critically compared the ability of AVS-SEM and dry weight-normalized concentrations to predict
toxicity of sediment-associated trace metals. Based on an analysis of 77 field-collected sediment
samples, Long et al. (1998) found that dry weight-normalized concentrations were equally or
slightly more accurate than AVS-SEM in predicting non-toxic and toxic results in laboratory
bioassays. Long et al. suggests that a limitation of the AVS-SEM approach is that the criteria
were not derived from field studies with mixture of toxic chemicals and thus may be less relevant
to sites comprising complex chemical mixtures. Thus, although the AVS-SEM approach for
developing sediment quality criteria is being pursued by the U.S. EPA, there is clearly not
scientific consensus on this approach, at least not for all circumstances.
Many alternative approaches for developing sediment quality guidelines are based on
empirical correlations between metal concentrations in sediment to associated biological effects,
based on sediment toxicity tests (Long et al., 1995; Ingersoll et al., 1996; MacDonald et al.,
2000). However, these guidelines are based on total metal concentrations in sediment and do not
account for the bioavailability of metals between sediments. Sediment quality guidelines
proposed for Pb from these other sources are shown in Table AX7-2.1.3.
Table AX7-2.1.3. Recommended Sediment Quality Guidelines for Lead
Source
MacDonald et al. (2000)
Ingersoll etal. (1996)
Long etal. (1995)
Water Type
Freshwater
Freshwater
Saltwater
Guideline Type
TEC
PEC
ERL
ERM
ERL
ERM
Cone, (mg/kg dw)
35.8
128
55
99
46.7
218
TEC = Threshold effect concentration; PEC = Probable effect concentration; ERL = Effects range - low;
ERM = Effects range - median
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AX7.2.1.5 Metal Mixtures
As discussed above, the EPA's current approach for developing sediment criteria for Pb
and other metals is to consider the molar sum of the metal concentrations (ZSEM). Although a
similar approach has not been applied to AWQC, metal mixtures have been shown to be more
toxic than individual metals (Spehar and Fiandt, 1986; Enserink et al., 1991). Spehar and Fiandt
(1986) evaluated the acute and chronic toxicity of a metal mixture (arsenic, cadmium, chromium,
copper, mercury, and Pb) to fathead minnows (Pimephalespromelas) and a daphnid
(Ceriodaphnia dubid). In acute tests, the joint toxicity of these metals was observed to be more
than additive for fathead minnows and nearly strictly additive for daphnids. In chronic tests, the
joint toxicity of the metals was less than additive for fathead minnows and nearly strictly
additive for daphnids. One approach for considering the additive toxicity of Pb with other metals
is to use the concept of toxic units (TUs). Toxic units for each component of a metal mixture are
derived by dividing metal concentrations by their respective acute or chronic criterion. The TUs
for all the metals in the mixture are then summed. A ETU > 1.0 suggests the metal mixture is
toxic (note that this is the same approach as discussed above for developing metal sediment
criteria based on pore water concentrations). According to Norwood et al. (2003), the TU
approach is presently the most appropriate model for predicting effects of metal mixtures based
on the currently available toxicity data. However, it should also be emphasized that the TU
approach is most appropriate at a screening level, because the true toxicity of the mixture is
dependent on the relative amounts of each metal. The TU approach is also recommended with
mixtures containing less than six metals.
Lead and other metals often co-occur in sediments with other toxicants, such as organic
contaminants. Effects-based sediment quality guidelines (SQGs) have been developed over the
past 20 years to aid in the interpretation of the relationships between complex chemical
contamination and adverse biological effects (Long et al., 2006). Mean sediment quality
guideline quotients (mSQGQs) can be calculated by dividing the concentrations of chemicals in
sediments by their respective SQGs and then calculating the mean of the quotients for the
individual chemicals. Long et al. (2006) performed a critical review of this approach and found
that it reasonably predicts the incidence and magnitude of toxicity in laboratory tests and the
incidence of impairment to benthic communities increases incrementally with increasing
mSQGQs. However, the authors pointed out some of the limitations of this approach, such as a
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lack of agreement on the level of mSQGQs, masking of an individual chemical's effect due to
data aggregation, lack of SQGs for all chemicals of concern, and mSQGQs were not initially
derived as a regulatory standard or criterion, thus there is a reluctance to use them in
enforcement or remediation (Long et al., 2006).
For assessing Pb effects on aquatic ecosystems, it is not truly feasible to account for metal
mixtures, because these will obviously vary highly from site to site. However, the toxicity of
metal mixtures in surface water should be considered on a site-specific basis.
AX7.2.1.6 Background Lead
Because Pb is naturally occurring, it is found in all environmental compartments
including surface water, sediment, and aquatic biota. Background Pb concentrations are spatially
variable depending on geological features and local characteristics that influence Pb speciation
and mobility. In the European Union risk assessments for metals, an "added risk" approach has
been considered that assumes only the amount of metal added above background is relevant in a
toxicological evaluation. However, this approach ignores the possible contribution of
background metal levels to toxic effects, and background metal levels are regionally variable,
precluding the approach from being easily transferable between sites. In terms of deriving
environmental criteria for Pb, background levels should be considered on a site-specific basis if
there is sufficient information that Pb concentrations are naturally elevated. As discussed
previously, the use of radiogenic Pb isotopes is useful for source apportionment.
AX7.2.2 Distribution of Lead in Aquatic Ecosystems
Atmospheric Pb is delivered to aquatic ecosystems primarily through deposition (wet
and/or dry) or through erosional transport of soil particles (Baier and Healy, 1977; Dolske and
Sievering, 1979; and Yang and Rose, 2005). A number of physical and chemical factors govern
the fate and behavior of Pb in aquatic systems. The EPA summarized some of these controlling
factors in the 1986 Lead AQCD (U.S. Environmental Protection Agency, 1986a). For example,
the predominant form of Pb in the environment is in the divalent (Pb2+) form and complexation
with inorganic and organic ligands is dependent on pH (Lovering, 1976; Rickard and Nriagu,
1978). A significant portion of Pb in the aquatic environment exists in the undissolved form
(i.e., bound to suspended particulate matter). The ratio of Pb in suspended solids to Pb in filtrate
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varies from 4:1 in rural streams to 27:1 in urban streams (Getz et al., 1977). In still waters, Pb is
removed through sedimentation at a rate determined by temperature, pH, oxidation-reduction
(redox) potential, organic content, grain size, and chemical form of Pb in the water and
biological activities (Jenne and Luoma, 1977). Since the publication of the 1986 Lead AQCD
(U.S. Environmental Protection Agency, 1986a), knowledge of the properties of Pb in aquatic
ecosystems has expanded. This section will provide further detail on the chemical species and
the environmental factors affecting speciation of Pb in the aquatic environment. In addition,
quantitative distributions of Pb in water, sediment, and biological tissues will be presented for
aquatic ecosystems throughout the United States. Finally, recent studies discussing the tracing of
Pb in aquatic systems will be summarized.
AX7.2.2.1 Speciation of Lead in Aquatic Ecosystems
The speciation of Pb in the aquatic environment is controlled by many factors. The
primary form of Pb in aquatic environments is divalent (Pb2+), while Pb4+ exists only under
extreme oxidizing conditions (Rickard and Nriagu, 1978). Labile forms of Pb (e.g., Pb2+,
PbOH+, PbCOs) are a significant portion of the Pb inputs to aquatic systems from atmospheric
washout. Lead is typically present in acidic aquatic environments as PbSO4, PbCl4, ionic Pb,
cationic forms of Pb-hydroxide, and ordinary Pb-hydroxide (Pb(OH)2). In alkaline waters,
common species of Pb include anionic forms of Pb-carbonate (Pb(CC>3)) and Pb(OH)2.
Speciation models have been developed based on the chemical equilibrium model developed by
Tipping (1994) to assist in examining metal speciation. The EPA MINTEQA2 computer model
(http://www.epa.gov/ceampubl/mmedia/minteq/) is one such equilibrium speciation model that
can be used to calculate the equilibrium composition of dilute aqueous solutions in the laboratory
or in natural aqueous systems. The model is useful for calculating the equilibrium mass
distribution among dissolved species, adsorbed species, and multiple solid phases under a variety
of conditions, including a gas phase with constant partial pressures. In addition to chemical
equilibrium models, the speciation of metals is important from a toxicological perspective.
The BLM was developed to study the toxicity of metal ions in aquatic biota and was previously
described in Section AX7.2.1.3. Further detail on speciation models is not provided herein,
rather a general overview of major speciation principles are characterized in the following
sections.
AX7-118
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Acidity (pH)
Freshwater
Most of the Pb in aquatic environments is in the inorganic form (Sadiq, 1992). The
speciation of inorganic Pb in freshwater aquatic ecosystems is dependent upon pH and the
available complexing ligands. Solubility varies according to pH, temperature, and water
hardness (Weber, 1993). Lead rapidly loses solubility above pH 6.5 (Rickard and Nriagu, 1978)
and as water hardness increases. In freshwaters, Pb typically forms strong complexes with
inorganic OH'and CO32! and weak complexes with Cl! (Long and Angino, 1977; Bodek et al.,
1988). The primary form of Pb at low pH (#6.5) is predominantly Pb2+ and less abundant
inorganic forms include Pb(HCO)3, Pb(SO4)22!, PbCl, PbCO3, and Pb2(OH)2CO3
(Figure AX7-2.2.1). At higher pH (37.5), Pb forms hydroxide complexes (PbOH+, Pb(OH)2,
Pb(OH)3!, Pb(OH)42!).
100
c
O
pH
Figure AX7-2.2.1. Distribution of aqueous lead species as a function of pH based on
a concentration of 1 ug Pb/L (U.S. Environmental Protection
Agency, 1999).
AX7-119
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Organic compounds in surface waters may originate from natural (e.g., humic or fulvic
acids) or anthropogenic sources (e.g., nitrilotriacetonitrile and ethylenediaminetetraacetic acid
[EDTA]) (U.S. Environmental Protection Agency, 1986b). The presence of organic complexes
has been shown to increase the rate of solution of Pb bound as Pb-sulfide (Lovering, 1976).
Soluble organic Pb compounds are present at pH values near 7 and may remain bound at pH
values as low as 3 (Lovering, 1976; Guy and Chakrabarti, 1976). At higher pH (7.4 to 9),
Pb-organic complexes are partially decomposed. Water hardness and pH were found to be
important in Pb-humic acid interactions (O'Shea and Mancy, 1978). An increase in pH
increased the concentration of exchangeable Pb complexes, while an increase in hardness tended
to decrease the humic acid-Pb interactions. Thus, the metals involved in water hardness
apparently inhibit the exchangeable interactions between metals and humic acids.
Marine Water
In marine systems, an increase in salinity increases complexing with chloride and
carbonate ions and reduces the amount of free Pb2+. In seawaters and estuaries at low pH, Pb is
primarily bound to chlorides (PbCl, PbCl2, PbCl3!, PbCl42!) and may also form inorganic
Pb(HCO)3, Pb(SO4)22!, or PbCO3. Elevated pH in saltwater environments results in the
formation of Pb hydroxides (PbOH+, Pb(OH)2, Pb(OH)3!, Pb(OH)42!) (Figure AX7-2.2.2).
A recent examination of Pb species in seawater as a function of chloride concentration suggested
that the primary species were PbCl3! > PbCO3 > PbCl2 > PbCl+ > and Pb(OH)+ (Fernando, 1995).
Lead in freshwater and seawater systems is highly complexed with carbonate ligands suggesting
that Pb is likely to be highly available for sorption to suspended materials (Long and Angino,
1977).
Current information suggests that inorganic Pb is the dominant form in seawater;
however, it has been shown that organically bound Pb complexes make up a large portion of the
total Pb (Capodaglio et al., 1990).
Sorption
Sorption processes (i.e., partitioning of dissolved Pb to suspended particulate matter or
sediments) appear to exert a dominant effect on the distribution of Pb in the environment
(U.S. Environmental Protection Agency, 1979). Sorption of Pb results in the enrichment of
AX7-120
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c
o
+3
5
+*
c
o
u
c
o
o
Figure AX7-2.2.2. Lead speciation versus chloride content (Fernando, 1995).
bed sediments, particularly in environments with elevated organic matter content from
anthropogenic sources. Lead adsorption to aquatic sediments is correlated with pollution in sites
containing high levels of anthropogenic organic content, even under acidic conditions (Tada and
Suzuki, 1982; Brook and Moore, 1988; Davis and Galloway, 1993; Botelho et al., 1994; Davis
et al., 1996). Particulate-bound forms are more often linked to urban runoff and mining effluents
(Eisler, 2000).
Solid Pb complexes form when Pb precipitates or adsorbs to suspended particulate matter
and sediments. Inorganic Pb adsorption to suspended organic matter or sediments is dependent
on parameters such as, pH, salinity, water hardness, and the composition of the organic matter
(U.S. Environmental Protection Agency, 1979). In addition to suspended organic matter, Pb can
adsorb to biofilms (i.e., bacteria) (Nelson et al., 1995; Wilson et al., 2001). Adsorption typically
increases with increasing pH, increasing amounts of iron or manganese; and with a higher degree
of polarity of the particulate matter (e.g., clays). Adsorption decreases with water hardness
(Syracuse Research Corporation, 1999). At higher pH, Pb precipitates as Pb(OH)+ and PbHCC>3+
into bed sediments (Weber, 1993). Conversely, at low pH, Pb is negatively sorbed (repelled
from the adsorbent surface) (U.S. Environmental Protection Agency, 1979; Gao et al., 2003).
In addition, Pb may be remobilized from sediment with a decrease in metal concentration in the
AX7-121
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solution phase, complexation with chelating agents (e.g., EDTA), and changing redox conditions
(Gao et al., 2003). Changes in water chemistry (e.g., reduced pH or ionic composition) can
cause sediment Pb to become remobilized and potentially bioavailable to aquatic organisms
(Weber, 1993).
Biotransformation
Methylation may result in Pb remobilization and reintroduction into the aqueous
environment compartment and its subsequent release into the atmosphere (Syracuse Research
Corporation., 1999). However, methylation is not a significant environmental pathway
controlling the fate of Pb in the aquatic environment. The microbial methylation of Pb in aquatic
systems has been demonstrated experimentally, but evidence for natural occurrence is limited
(Beijer and Jernelov, 1984; DeJonghe and Adams, 1986). Reisinger et al. (1981) examined the
methylation of Pb in the presence of numerous bacteria known to alkylate metals and did not find
evidence of Pb methylation under any test condition. Tetramethyl-Pb may be formed by the
methylation of Pb-nitrate or Pb-chloride in sediments (Bodek et al., 1988). However,
tetramethyl-Pb is unstable and may degrade in aerobic environments after being released from
sediments (U.S. Environmental Protection Agency, 1986b). Methylated species of Pb may also
be formed by the decomposition of tetralkyl-Pb compounds (Radojevic and Harrison, 1987;
Rhue et al., 1992). Sadiq (1992) reviewed the methylation of Pb compounds and suggested that
chemical methylation of Pb is the dominant process and that biomethylation is of secondary
importance.
AX7.2.2.2 Spatial Distribution of Lead in Aquatic Ecosystems
National Water Quality Assessment (NA WO A)
The 1986 Lead AQCD (U.S. Environmental Protection Agency, 1986b) did not describe
the distribution and concentration of Pb throughout aquatic ecosystems of the United States.
Consequently, an analysis of readily available data on Pb concentrations was conducted to
determine the distribution of Pb in the aquatic environment. Data from the United States
Geological Survey (USGS) National Water-Quality Assessment (NAWQA) program were
queried and retrieved. NAWQA contains data on Pb concentrations in surface water, bed
sediment, and animal tissue for more than 50 river basins and aquifers throughout the country,
AX7-122
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and it has been used by the EPA for describing national environmental concentrations for use in
developing AWQC. The authors recognize that the NAWQA program encountered analytical
challenges with the chemical analysis of Pb in surface waters. The analytical methods available
during the NAWQA program were not as sensitive as methods currently applied today.
Therefore, analytical detection limits are elevated and a large portion of the data set contains
non-detected values. Nevertheless, this data provides a comprehensive overview of Pb
concentrations in U.S. surface waters that is supplemented with data from other relevant studies.
The following sections describe the estimated concentrations of Pb from NAWQA and other
research programs.
NAWQA data are collected during long-term, cyclical investigations wherein study units
undergo intensive sampling for 3 to 4 years, followed by low-intensity monitoring and
assessment of trends every 10 years. The NAWQA program's first cycle was initiated in 1991;
therefore, all available data are less than 15 years old. The second cycle began in 2001 and is
ongoing; data are currently available through 30 September 2003. The NAWQA program study
units were selected to represent a wide variety of environmental conditions and contaminant
sources; therefore, agricultural, urban, and natural areas were all included. Attention was also
given to selecting sites covering a wide variety of hydrologic and ecological resources.
NAWQA sampling protocols are designed to promote data consistency within and among
study units while minimizing local-scale spatial variability. Water-column sampling is
conducted via continuous monitoring, fixed-interval sampling, extreme-flow sampling, as well as
seasonal, high-frequency sampling in order to characterize spatial, temporal, and seasonal
variability as a function of hydrologic conditions and contaminant sources. Sediment and tissue
samples are collected during low-flow periods during the summer or fall to reduce seasonal
variability. Where possible, sediment grab samples are collected along a 100-m stream reach,
upstream of the location of the water-column sampling. Five to ten deposit!onal zones at various
depths, covering left bank, right bank, and center channel, are sampled to ensure a robust
representation of each site. Fine-grained samples from the surficial 2 to 3 cm of bed sediment at
each depositional zone are sampled and composited. Tissue samples are collected following a
National Target Taxa list and decision trees that help guide selection from that list to
accommodate local variability.
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The NAWQA dataset was chosen over other readily available national databases (i.e. the
USEPA-maintained database for the STOrage andRETrieval [STORET] of chemical, physical,
and biological data), because the study design and methods used to assess the water quality of
each study unit are rigorous and consistent, and, as such, these data may be presented with a high
level of confidence. This is in stark contrast to the STORET database, which essentially serves
as a depot for any organization wishing to share data they have generated. This lack of a
consistent methodology or QA/QC protocol has lead to the STORET data being highly qualified
and offered with only a mild level of confidence. Furthermore, because there is no standard for
site selection within STORET, the database may be biased toward contaminated sites. Finally,
and, perhaps most importantly, the majority of the available Pb data in STORET predate the use
of clean techniques for Pb quantification.
The authors recognize the existence of several local and regional datasets that may be of
quality equal to NAWQA; however, due to the national scope of this assessment, these datasets
were not included in the following statistical analyses. However, because the NAWQA database
does not cover lakes and the marine/estuarine environment, and we were unable to identify any
monitoring data of similar quality, local and regional datasets were used in these cases to provide
general information on environmental Pb concentrations.
Data Acquisition and Analysis
The following data were downloaded for the entire United States (all states) from the
NAWQA website (http://water.usgs.gov/nawqa/index.html): site information, dissolved Pb
concentration in surface water (|ig/L), total Pb concentration (|ig/g) in bed sediment (<63 |im)3,
and Pb concentration in animal tissue (|ig/g dw). Using the land use classification given for each
site, the data were divided into two groups: "natural" and "ambient" (Table AX7-2.2.1).
All samples were considered to fall within the ambient group (the combined contribution of
natural and anthropogenic sources), whereas the natural group comprised "forest," "rangeland,"
or "reference" samples only4. These groups follow those defined and recommended for use by
the EPA's Framework for Inorganic Metals Risk Assessment (U.S. Environmental Protection
3 NAWQA sediment samples are sieved to <63 um to promote the collection of fine-grained surficial
sediments, which are natural accumulators of trace elements.
4 The authors acknowledge that while Pb samples collected from sites classified under these three land use
categories will most closely reflect natural background concentrations, atmospheric input of lead may be present.
AX7-124
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Table AX7-2.2.1. NAWQA Land Use Categories and
Natural/Ambient Classification
NAWQA Land Use Categories
Agricultural
Commercial/Industrial
Cropland
Forest
Mining
Mixed
NA
Orchard/Vineyard
Other/Mixed
Pasture
Rangeland
Reference
Residential
Urban
Classification
Ambient
Ambient
Ambient
Ambient/Natural
Ambient
Ambient
Ambient
Ambient
Ambient
Ambient
Ambient/Natural
Ambient/Natural
Ambient
Ambient
Agency, 2004b). Finally, in addition to the natural/ambient classification, tissue samples were
further divided into "whole organism" and "liver" groups.
All data were compiled in spreadsheets wherein non-detect values were converted to one-
half the detection limit and the total number of samples, percentage of non-detect values (percent
censorship), minimum, maximum, median, mean, standard deviation, and cumulative density
functions were calculated for each endpoint for both the natural and ambient groups.
As discussed below, some datasets were highly censored; however, deletion of non-detect data
has been shown to increase the relative error in the mean to a greater extent than inclusion of
non-detects as 1A of the detection limit (Newman et al., 1989); therefore means and other
statistics were calculated using the latter method for this analysis. Finally, since all data were
geo-referenced, a geographic information system (GIS; ArcGIS) was used to generate maps,
conduct spatial queries and analyses, and calculate statistics.
AX7-125
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Lead Distributions Generated from the NAWQA Database
Natural versus Ambient Groups
There were four to eight times more ambient surface water (Table AX7-2.2.2) and bulk
sediment (Table AX7-2.2.3) samples in the compiled dataset than natural samples. This is most
likely a function of both the NAWQA program site selection process and the fact that sites
unaffected by human activities are extremely limited. The spatial distributions of natural and
ambient surface water/sediment sites were fairly comparable, with natural samples located in
almost all of the same areas as ambient samples except in the Midwest (Ohio, Illinois, Iowa, and
Michigan), where natural sites were not present (Figure AX7-2.2.3). This exception may be
because these areas are dominated by agricultural and urban areas. The same spatial
distributions were observed for the natural and ambient liver and whole organism tissue
samples (Figure AX7-2.2.4 and Figure AX7-2.2.5).
Table AX7-2.2.2. Summary Statistics of Ambient and Natural Levels of
Dissolved Lead in Surface Water
Surface Water Dissolved Pb (ug/L)
Statistic
% Censorship
N
Minimum
Maximum
Mean
Standard Deviation
Median
90th Percentile
95th Percentile
96th Percentile
97th Percentile
98th Percentile
99th Percentile
Natural
87.91
430
0.04
8.40
0.52
0.59
0.50
0.50
0.50
0.67
1.00
1.79
2.48
Ambient
85.66
3445
0.04
29.78
0.66
1.20
0.50
0.50
1.10
2.00
2.34
3.58
5.44
AX7-126
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Table AX7-2.2.3. Summary Statistics of Ambient and Natural Levels of Total Lead in
<63 jim Bulk Sediment
Bulk Sediment <63 um Total Lead (ug/g)
Statistic
% Censorship
N
Minimum
Maximum
Mean
Standard Deviation
Median
90th percentile
95th percentile
Natural
1.16
258
0.50
12000
109.07
786.74
22.00
66.30
161.50
Ambient
0.48
1466
0.50
12000
120.11
672.41
28.00
120.00
200.00
Surface Water
The total number of surface water Pb samples was 3,445; however these data were highly
censored with 85.66% of the ambient samples (2951/3445) and 87.91% of the natural samples
(378/430) below the detection limit5 (Table AX7-2.2.2). Consequently, the majority of the
variability between these two datasets fell between the 95th and 100th (maximum) percentiles,
as was shown by the frequency distributions of the two groups deviating only at the upper and
lower tails with most of the overlapping data falling at 0.50 |ig/L (one-half of the most common
detection limit, 1.0 |ig/L; Figure AX7-2.2.6). As expected, due to the definitions of the natural
and ambient groups, the 95th and 100th percentiles were consistently higher for the ambient
samples than the natural samples. Similarly, the mean ambient Pb concentration (0.66 |ig/L)
was higher than the mean natural Pb concentration (0.52 |ig/L).6
5 The NAWQA dataset contains multiple detection limits for Pb in surface water that have decreased over
time. While the majority of data were analyzed with a detection limit of 1.0 ug/L (before 2000/2001), the most
recent samples were analyzed with either a 0.5, 0.2, 0.16, or 0.08 ug/L detection limit (after 2000/2001), and some
older samples (N = 20) were analyzed with a detection limit of 2.0 ug/L.
6 The same pattern was observed upon calculating the mean Pb concentrations based on detect data only
(ambient mean = 1.66 ug/L, natural mean = 0.87 ug/L); however, as previously discussed, calculations included
non-detect data as 1A of the detection limit to reduce the relative error in the mean.
AX7-127
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to
Legend
• Natural Surface Water/Sediment Sites
O Ambient Surface Water/Sediment Sites
Figure AX7-2.2.3. Spatial distribution of natural and ambient surface water/sediment sites (Surface water: natural N = 430,
ambient N = 3445; Sediment: natural N = 258, ambient N = 1466).
-------
to
Legend
• Natural Liver Sites
o Ambient Liver Sites
Figure AX7-2.2.4. Spatial distribution of natural and ambient liver tissue sample sites (Natural N = 83, Ambient N = 559).
-------
o
Legend
• Natural Whole Organism Sites
O Ambient Whole Organism Sites
Figure AX7-2.2.5. Spatial distribution of natural and ambient whole organism tissue sample sites (Natural N = 93,
Ambient N = 332).
-------
•Ambient Natural
100
g 80
> 60
D 40
5 20
0.0 0.1 1.0 10.0 100.0
Surface Water Dissolved Pb (ug/L)
Figure AX7-2.2.6. Frequency distribution of ambient and natural levels of surface water
dissolved lead (ug/L).
Due to the preponderance of non-detectable (ND) measurements, assessing national trends
in surface water-dissolved Pb concentrations was not possible. However, areas with elevated Pb
concentrations were identified by classifying the data with detectable Pb concentrations above
and below the 99th percentile. The 99th percentile (versus the 95th percentile) was chosen in
this instance to represent extreme conditions given the small window of variability in the dataset.
By convention, the 95th percentile was used in subsequent analyses of this type. Areas with high
surface water Pb concentrations were observed in Washington, Idaho, Utah, Colorado, Arkansas,
and Missouri (Figure AX7-2.2.7). The maximum measured Pb concentration was located in
Canyon Creek at Woodland Park, ID, a site classified as mining land use.
Sediment
There were approximately one-half of the number of surface water data available for
sediments (N = 1466). In contrast to the surface water data, however, very few sediment data
were below the detection limit (7/1466 ambient ND, 3/258 natural ND; Table AX7-2.2.3).
As expected, the mean ambient Pb concentration was higher than the mean natural Pb
AX7-131
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X
to
Legend
Surface Water Dissolved Pb (ug/L)
o Non-detect
0 0.51 - 5.44 (<99th precentile)
5.45 - 29.78 (>99th percentile)
Figure AX7-2.2.7. Spatial distribution of dissolved lead in surface water (N = 3445).
-------
concentration (120.11 and 109.07 |ig/g, respectively). Similarly, the median ambient Pb
concentration was higher than the median natural Pb concentration (28.00 and 22.00 |ig/g,
respectively) and the ambient 95th percentile was higher than the natural 95th percentile
(200.00 and 161.50 |ig/g, respectively). While the natural and ambient surface water Pb
distributions differed only at the extremes, the natural sediment Pb percentiles were consistently
lower than the ambient percentiles throughout the distributions (Figure AX7-2.2.8). Unlike the
surface water dataset, because the sediment dataset was not heavily censored, assessing national
trends in sediment Pb concentrations was possible. The data were mapped and categorized into
the four quartiles of the frequency distribution (Figure AX7-2.2.9). The following observations
were made:
• Sediment Pb concentrations generally increased from west to east (the majority of
sites along East Coast had Pb concentrations in the fourth quartile of the sediment Pb
concentration frequency distribution).
• Several "hot spots" of concentrated sites with elevated sediment Pb concentrations
were apparent in various western states.
• Sediment Pb concentrations were generally lowest in the midwestern states
(the majority of sites in North Dakota, Nebraska, Minnesota, and Iowa had Pb
concentrations in the first or second quartile of sediment Pb concentration
frequency distribution).
As was seen with surface water Pb concentrations, the highest measured sediment Pb
concentrations were found in Idaho, Utah, and Colorado. Not surprisingly, of the top 10
sediment Pb concentrations recorded, 7 were measured at sites classified as mining land use.
Tissue
As was true for the surface water data, there were a high number of tissue samples below
the detection limit (47/93 natural whole organism ND, 130/332 ambient whole organism ND,
74/83 natural liver ND, 398/559 ambient liver ND; Table AX7-2.2.4). In general, more
non-censored data were available for whole organism samples than liver samples, and for
ambient sites than natural sites. As expected, for whole organism samples, the 95th percentile Pb
concentration measured at ambient sites was higher than that measured at natural sites (3.24 and
2.50 |ig/g, respectively); however, Pb liver concentration 95th percentiles for ambient and
natural samples were very similar, with the natural 95th percentile actually higher than the
AX7-133
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100
• Ambient Natural
1 10 100 1000 10000 100000
Bulk Sediment <63|jm Total Pb
Figure AX7-2.2.8. Frequency distribution of ambient and natural levels of bulk sediment
<63 jim total Pb (ug/g).
ambient 95th percentile (1.26 and 1.06 |ig/g, respectively). In addition, as expected, the median
and mean Pb liver concentrations of ambient samples (0.15 and 0.36 jig/g, respectively) were
higher than the median and mean Pb liver concentrations of natural samples (0.11 and 0.28 |ig/g,
respectively). The same pattern was observed in the whole organism median and mean Pb
concentrations (ambient: median = 0.59, mean = 1.03; natural: median = 0.35, mean =
0.95 |ig/g). In addition, the frequency distributions of the liver and whole organism Pb
concentrations followed the same trends, with the natural percentiles consistently lower than the
ambient percentiles throughout the distributions (Figure AX7-2.2.10 and Figure AX7-2.2.11).
These whole organism results were compared with findings from the 1984 U.S. Fish and
Wildlife Service (USFWS) National Contaminant Biomonitoring Program (NCBP) (Schmitt and
Brumbaugh, 1990). As part of this program, 321 composite samples of 3 to 5 whole, adult fish
of a single species were collected from 109 river and Great Lake stations throughout the country.
Samples were analyzed for Pb concentrations (|ig/g ww) and the geometric mean, maximum, and
85th percentile were calculated. Upon comparing these summary statistics with the equivalent
NAWQA ambient group value (NCBP stations were representative of both natural and
anthropogenically influenced conditions), a very strong agreement between the two analyses was
AX7-134
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Legend
Bulk Sediment <63|j Total Lead (jjg/g)
0 0.50- 18.00{1stQuartile)
0 18.01 - 28.00 (2nd Quartile)
• 28.01 - 49.00 (3rd Quartile)
• 49.01 - 12000.00 (4th Quartile)
X
Figure AX7-2.2.9. Spatial distribution of total lead in bulk sediment <63 um (N = 1466).
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Table AX7-2.2.4. Summary Statistics of Ambient and Natural Levels of Lead
in Whole Organism and Liver Tissues
Tissue Pb (jig/g dry weight)
Statistic
% Censorship
N
Minimum
Maximum
Mean
Standard Deviation
Median
90th percentile
95th percentile
Whole
Natural
50.54
93
0.08
22.60
0.95
2.53
0.35
1.40
2.50
Organism
Ambient
39.16
332
0.08
22.60
1.03
1.74
0.59
2.27
3.24
Natural
89.16
83
0.01
3.37
0.28
0.54
0.11
0.37
1.26
Liver
Ambient
71.20
559
0.01
12.69
0.36
0.96
0.15
0.59
1.06
observed for each endpoint (Table AX7-2.2.5). For example, NCBP and NAWQA geometric
mean Pb concentrations were nearly identical (0.55 and 0.54 |ig/g dw, respectively) and the
85th percentiles only differed by 0.5 |ig Pb/g dw (NCBP, 1.10 and NAWQA, 1.60). The authors
acknowledge that a high degree of censorship is present in both of these datasets and no firm
conclusions can be drawn by comparing these means. The objective of this exercise was limited
to showing how the NAWQA data compare to other national datasets.
As was the case with surface water data, the high amount of non-detectable measurements
did not allow for a national assessment of spatial trends in Pb tissue concentrations. Instead,
areas with high Pb tissue concentrations were identified by classifying the data above and below
the 95th percentile. Similar to surface water and sediments, tissue concentrations were found to
be elevated in Washington, Idaho, Utah, Colorado, Arkansas, and Missouri; however, several of
the highest measured Pb concentrations were also found in study units in the southwestern and
AX7-136
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100
* Ambient u Natural
0.01
0.1 1 10
Liver Pb (M9/9 dry weight)
Figure AX7-2.2.10. Frequency distribution of ambient and natural levels of lead in liver
tissue (ug/g dry weight).
100
0.01 0.1 1 10 100
Whole Organism Pb (Mg/g dry weight)
Figure AX7-2.2.11. Frequency distribution of ambient and natural levels of lead in whole
organism tissue (ug/g dry weight).
AX7-137
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Table AX7-2.2.5. Comparison of NCBP and NAWQA Ambient Lead Levels
in Whole Organism Tissues
Whole Organism Lead Concentration (jig/g dry weight)
Statistic NCBP1 NAWQA
Geometric Mean 0.55 0.54
Maximum 24.40 22.60
85th Percentile 1.10 1.60
1 To convert between wet and dry weight, wet weight values were multiplied by a factor of five.
southeastern states (Figure AX7-2.2.12 and Figure AX7-2.2.13). As expected, the majority of
the samples with elevated Pb concentrations were taken from sites classified as urban,
commercial/industrial, or mining.
Input and Distribution of Lead in Other Aquatic Systems
Because the NAWQA database does not cover lakes or the sea where atmospheric
deposition of Pb is highly likely, the primary literature was searched for studies using ultra-clean
sampling/analytical techniques to characterize Pb concentrations in these environments. Lead
concentrations in lakes and oceans were generally found to be much lower than those measured
in the lotic waters assessed by NAWQA. Surface water concentrations of dissolved Pb measured
in Hall Lake, Washington in 1990 ranged from 2.1 - 1015.3 ng/L (Balistrieri et al., 1994).
Nriagu et al. (1996) found that the average surface water dissolved Pb concentrations measured
in the Great Lakes (Superior, Erie, and Ontario) between 1991 and 1993 were 3.2, 6.0, and
9.9 ng/L, respectively. Lead concentrations ranged from 3.2 - 11 ng/L across all three lakes.
Similarly, 101 surface water total Pb concentrations measured at the HOT station ALOHA
between 1998 and 2002 ranged from 25 - 57 pmol/kg (5-11 ng/kg; (Boyle et al., 2005). Based
on the fact that Pb is predominately found in the dissolved form in the open ocean (<90%;
Schaule and Patterson, 1981), dissolved Pb concentrations measured at these locations would
likely have been even lower than the total Pb concentrations reported.
AX7-138
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X
VO
Legend
Liver Lead (pg/g dry weight)
O Non -detect
0 0.10-1.06 (<95th precentile)
1.06 -12.69 (>95th precentile)
Figure AX7-2.2.12. Spatial distribution of lead in liver tissues (N = 559).
-------
X
Legend
Whole organism Lead (pg/g dry weight)
O Non-detect
0 0.20 - 3.24 (<95th precentile)
3.24 - 22.60 (>95th precentile)
Figure AX7-2.2.13. Spatial distribution of lead in whole organism tissues (N = 332).
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In open waters of the North Atlantic the decline of Pb concentrations has been associated
with the phasing out of leaded gasoline in North America and western Europe (Veron et al.,
1998). Likewise, Pb restrictions in gasoline appear to have been effective in reducing
atmospheric Pb loading to the Okefenokee Swamp in southern Georgia/northern Florida
(Jackson et al., 2004). Based on sediment cores from the Okefenokee Swamp, Pb concentrations
were approximately 0.5 mg/kg prior to industrial development, reached a maximum of
approximately 31 mg/kg from about 1935 to 1965, and following passage of the Clean Air Act in
1970 concentrations have declined to about 18 mg/kg in 1990 (Jackson et al., 2004). Trends in
metals concentrations (roughly 1970-2001) in sediment cores from 35 reservoirs and lakes in
urban and reference settings were analyzed by Mahler et al. (2006) to determine the effects of
three decades of legislation, regulation, and changing demographics and industrial practices in
the United States on concentrations of metals in the environment. The researchers found that
decreasing trends outnumbered increasing trends for all seven metals analyzed (Cd, Cr, Cu, Pb,
Hg, Ni, and Zn). The most consistent trends were for Pb and Cr: For Pb, 83% of the lakes had
decreasing trends and 6% had increasing trends; for Cr, 54% of the lakes had decreasing trends
and none had increasing trends. Mass accumulation rates of metals in cores, adjusted for
background concentrations, decreased from the 1970s to the 1990s, where median changes
ranged from 246% (Pb) to 23% (Hg and Zn). The largest decreases were found in lakes located
in dense urban watersheds where the overall metals contamination in recently deposited
sediments decreased to on-half its 1970s median value. However, Mahler et al. (2006) found
that anthropogenic mass accumulation rates in dense urban lakes remained elevated over those in
lakes in undeveloped watersheds, in some cases by as much as two orders of magnitude (Cr, Cu,
and Zn), indicating that urban fluvial source signals can overwhelm those from regional
atmospheric sources. In estuarine systems, however, it appears that similar declines following
the phase-out of leaded gasoline are not necessarily as rapid. Steding et al. (2000) used isotopic
evidence to demonstrate the continued cycling of Pb in the San Francisco Bay estuary. In the
southern arm of San Francisco Bay, which has an average depth of <2 m, Steding et al. (2000)
found that isotopic compositions were essentially invariant, with 90% of the Pb derived from
1960s-1970s leaded gasoline. The authors attributed this to the limited hydraulic flushing and
remobilization of Pb from bottom sediments. In the northern arm of San Francisco Bay,
although seasonal and decadal variations in Pb isotope composition were observed, mass balance
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calculations indicate that only a small fraction of leaded gasoline fallout from the late 1980s has
been washed out of the San Joaquin and Sacramento rivers' drainage basin by 1995 and
consequently freshwater inputs remain a Pb source to the bay (Steding et al., 2000). The authors
suggest that the continuous source of Pb from the river systems draining into the bay, coupled
with benthic remobilization of Pb, indicates that historic gasoline deposits may remain in the
combined riparian/estuarine system for decades.
AX7.2.2.3 Tracing the Fate and Transport of Lead in Aquatic Ecosystems
The following section presents a generalized framework for the fate and transport of Pb in
aquatic systems (Figure AX7-2.2.14). The primary source of Pb in natural systems is
atmospheric deposition (Rickard and Nriagu, 1978; U.S. Environmental Protection Agency,
1986a). Estimated median global atmospheric emission for anthropogenic and natural sources
are 332 H 106 kg/year and 12 H 106 kg/year, respectively (summarized by Giusti et al., 1993).
Inorganic and metallic Pb compounds are nonvolatile and will partition to airborne particulates
or water vapors (Syracuse Research Corporation., 1999). Dispersion and deposition of Pb is
dependent on the particle size (U.S. Environmental Protection Agency, 1986a; Syracuse
Research Corporation., 1999). More soluble forms of Pb will be removed from the atmosphere
by washout in rain.
In addition to atmospheric deposition, Pb may enter aquatic ecosystems through industrial
or municipal wastewater effluents, storm water runoff, erosion, or direct point source inputs
(e.g., Pb shot or accidental spills). Once in the aquatic environment, Pb will partition between
the various compartments of the system (e.g., dissolved phase, solid phase, biota). The
movement of Pb between dissolved and particulate forms is governed by factors such as pH,
sorption, and biotransformation (see Section AX7.2.2.1). Lead bound to organic matter will
settle to the bottom sediment layer, be assimilated by aquatic organisms, or be resuspended in the
water column. The uptake, accumulation, and toxicity of Pb in aquatic organisms from water
and sediments are influenced by various environmental factors (e.g., pH, organic matter,
temperature, hardness, bioavailability). These factors are further described in Section
AX7.2.3.4). The remainder of this section discusses some methods for describing the
distribution of atmospheric Pb in the aquatic environment.
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Figure AX7-2.2.14. Lead cycle in an aquatic ecosystem.
Sediment Core Dating and Source Tracing
In addition to directly measuring Pb concentrations in various aquatic compartments (see
Section AX7.2.3.3), it is useful to study the vertical distribution of Pb. Sediment profiling and
core dating is a method used to determine the extent of accumulation of atmospheric Pb and
provide information on potential anthropogenic sources. Sediment concentration profiles are
typically coupled with Pb isotopic analysis. The isotope fingerprinting method utilizes
measurements of the abundance of common Pb isotopes (i.e., 204Pb, 206Pb, 207Pb, 208Pb) to
distinguish between natural Pb over geologic time and potential anthropogenic sources. Details
of this method were described in Section AX7.1.2. The concentration of isotope 204Pb has
remained constant throughout time, while the other isotope species can be linked to various
anthropogenic Pb sources. Typically, the ratios or signatures of isotopes (e.g., 207Pb:206Pb) are
compared between environmental samples to indicate similarities or differences in the site being
investigated and the potential known sources.
Generally, Pb concentrations in sediment vary with depth. For example, Chow et al.
(1973) examined sediment Pb profiles in southern California. Lead concentrations were
increased in the shallower sediment depths and comparatively decreased at greater depths. These
changes in sediment vertical concentration were attributed to higher anthropogenic Pb fluxes
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from municipal sewage, storm runoff, and atmospheric deposition. Similar experiments
conducted throughout the United States have also suggested an increase in Pb concentrations in
the upper sediment layer concomitant with increases in anthropogenic inputs (Bloom and
Crecelius, 1987; Case et al., 1989; Ritson et al., 1999; Chillrud et al., 2003).
Sediment Pb concentration profiles and isotope analysis have also been used to identify
specific anthropogenic sources. For example, Flegal et al. (1987) used isotopic ratios to trace
sources of Pb in mussels from Monterey Bay, CA to a specific slag deposit. Several
investigators have examined isotopic tracers to determine potential regional sources of Pb in
eastern North America and the Great Lakes (Flegal et al., 1989b; Graney et al., 1995; Blais,
1996). Water samples from Lake Erie and Lake Ontario were collected and analyzed. Lead
isotope ratios (206Pb:207Pb) from the lakes were compared to known ratios for Pb aerosols derived
from industrial sources in Canada and the United States and found to correlate positively. This
indicated that a majority of Pb in the lakes was derived from those industrial sources (Flegal
et al., 1989b). Similarly, Gallon et al. (2006) used 206Pb:207Pb ratios in sediment cores collected
from a 300 km transect in Canadian Shield headwater lakes to differentiate Pb contributions from
smelter emissions relative to Pb contributions from other anthropogenic inputs. The authors
were able to estimate the amounts of smelter-derived Pb in sediment collected along the 300 km
transect. Lead isotopes in sediment cores from Quebec and Ontario, Canada were also used to
distinguish between the amount of Pb deposited from local Canadian sources (28.4 to 61.7%)
and U.S. sources (38.3 to 71.6%) (Blais, 1996). Examination of Pb isotopes in sediment and
suspended sediment in the St. Lawrence River were used to identify potential anthropogenic Pb
sources from Canada (Gobeil et al., 1995, 2005). Graney et al. (1995) used Pb isotope
measurements to describe the differing historic sources of Pb in Lake Erie, Ontario and in
Michigan. Temporal changes in Pb isotopic ratios were found to correspond to sources such as
regional deforestation from 1860 through 1890, coal combustion and or smelting through 1930,
and the influence of leaded gasoline consumption from 1930 to 1980.
The historic record of atmospheric Pb pollution has been studied to understand the natural
background Pb concentration and the effects of Pb accumulation on ecosystems (Bindler et al.,
1999; Renberg et al., 2000, 2002; Brannvall et al., 2001a,b). The most extensive work in this
area has been conducted at pristine locations in Sweden (Bindler et al., 1999). In this study, soil,
sediment, and tree rings were sampled for Pb concentrations and isotopic analyses were
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conducted on the soil samples. From this record, historic Pb concentrations and Pb accumulation
rates were estimated. Present day concentrations in the forest soils ranged from 40 to 100 mg/kg,
while a natural background concentration was estimated at <1 mg/kg. The authors were able to
model Pb concentrations for the past 6,000 years and also to project Pb concentrations for the
next 400 years, given an assumed atmospheric deposition rate of 1 mg Pb m!2/year. Models such
as this are useful tools in determining the critical limits of metals in soils or sediments (Bindler et
al., 1999; Renberg et al., 2002).
Lead source association may also be assessed through retrospective measurements.
Squire et al. (2002) used a time-series approach to evaluate the change in Pb in San Francisco
Bay, CA from 1989 to 1999. This approach involved the use of detailed linear regression models
and long-term monitoring data to determine changes in Pb concentrations and to identify events
corresponding to those changes. Sediment and water samples were collected throughout the bay
and combined with data on effluent discharges, urban runoff, atmospheric deposition, and river
discharges. The authors identified a 40% decline of Pb in the southern portion of the bay but
found no change in the northern reach. The decline was attributed to a reduction in wastewater
source loadings over the previous decade.
AX7.2.2.4 Summary
Lead is widely distributed in aquatic ecosystems, predominantly originating from
atmospheric deposition or point source contribution. The fate and behavior of Pb in aquatic
systems is regulated by physical and chemical factors such as pH, salinity, sediment sorption,
transformation, and uptake by aquatic biota. In the United States, Pb concentrations in surface
waters, sediments, and fish tissues range from 0.04 to 30 |ig/L, 0.5 to 12,000 mg/kg, and 0.08 to
23 mg/kg, respectively. Atmospheric sources are generally decreasing, as the United States has
removed Pb from gasoline and other products. However, elevated Pb concentrations remain at
sites associated with mining wastes or wastewater effluents. Since the 1986 Lead AQCD, much
has been learned about the processes affecting Pb fate and transport. Detailed analyses are
currently available (i.e., Pb isotope dating) to allow for constructing the history of Pb
accumulation and identifying specific Pb contaminant sources. Continued source control along
with examination of the physical and chemical properties will further allow for the reduction of
Pb concentrations throughout the United States.
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AX7.2.3 Aquatic Species Response/Mode of Action
Recent advancements in understanding the responses of aquatic biota to Pb exposure are
highlighted in this section. A summary of the conclusions on the review of aquatic responses to
Pb from the appropriate sections of the 1986 Lead AQCD, Volume II (U.S. Environmental
Protection Agency, 1986a) and the subsequent conclusions and recommendations contained in
the EPA staff review of that document (U.S. Environmental Protection Agency, 1990) are also
provided. In addition, this section summarizes research subsequent to the 1986 Lead AQCD on
Pb uptake into aquatic biota, effects of Pb speciation on uptake, resistance mechanisms to Pb
toxicity, physiological effects of Pb, factors that affect responses to Pb, and factors associated
with global climate change. Areas of research that are not addressed here include literature
related to exposure to Pb shot or pellets and studies that examine human health-related endpoints
(e.g., hypertension), which are described in other sections of this document.
AX7.2.3.1 Lead Uptake
Lead is nutritionally nonessential and non-beneficial and is toxic to living organisms in all
of its forms (Eisler, 2000). Lead can bioaccumulate in the tissues of aquatic organisms through
ingestion of food and water and adsorption from water (Vazquez et al., 1999; Vink, 2002) and
subsequently lead to adverse effects if tissue levels are sufficiently high (see Section AX7.2.5).
Recent research has suggested that due to the low solubility of Pb in water, dietary Pb (i.e., lead
adsorbed to sediment, particulate matter, and food) may contribute substantially to exposure and
toxicity in aquatic biota (Besser et al., 2005). Besser et al. (2004) exposed the amphipod
Hyalella azteca to concentrations of Pb to evaluate the influence of waterborne and dietary Pb
exposure on acute and chronic toxicity. The authors found that acute toxicity was unaffected by
dietary exposure but that dietary Pb exposure did contribute to chronic toxic effects (i.e.,
survival, growth, reproduction) in H. azteca. Field studies in areas affected by metal
contamination (i.e., Clark Fork River, MO; Coeur d'Alene, ID) (Woodward et al., 1994, 1995;
Farag et al., 1994) have also demonstrated the effects of dietary metals on rainbow trout.
However, there has been a debate on the importance of dietary exposure, as few controlled
laboratory studies have been able to replicate the effects observed in the field studies (Hodson
et al., 1978; Mount, 1994; Erikson, 2001). This may be due to differences in the availability of
Pb from the dietary sources used in laboratory studies, differences in speciation, and/or
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nutritional characteristics of the Pb dosed diets. In many field and laboratory studies, dietary
exposure is rarily considered, but food provided to biota in these studies adsorb metals from
water. Therefore, both dietary and waterborne exposure are occurring and both may be
considered to play roles in eliciting the measured effects.
Lead concentrations in the tissues of aquatic organisms are generally higher in algae and
benthic organisms and lower in higher trophic-level consumers (Eisler, 2000). Thus, trophic
transfer of Pb through food chains is not expected (Eisler, 2000). Metals are not metabolized;
therefore, they are good integrative indicators of exposure in aquatic biota (Luoma and Rainbow,
2005). Metal uptake is complex, being influenced by geochemistry, route of exposure (diet and
adsorption), depuration, and growth (Luoma and Rainbow, 2005). This section discusses the
factors affecting uptake of Pb by aquatic biota and the state of current research in this area.
As described in Section AX7.2.2.1, the solubility of Pb in water varies with pH,
temperature, and ion concentration (water hardness) (Weber, 1993). Lead becomes soluble and
bioavailable under conditions of low pH, organic carbon content, suspended sediment
concentrations, and ionic concentrations (i.e., low Cd, Ca, Fe, Mn, Zn) (Eisler, 2000). Lead
rapidly loses solubility above pH 6.5 (Rickard and Nriagu, 1978) and precipitates out as Pb(OH)+
and PbHCC>3+ into bed sediments. However, at reduced pH levels or ionic concentrations,
sediment Pb can remobilize and potentially become bioavailable to aquatic organisms (Weber,
1993).
The most bioavailable inorganic form of Pb is divalent Pb (Pb2+), which tends to be more
readily assimilated by organisms than complexed forms (Erten-Unal et al., 1998). On the other
hand, the low solubility of Pb salts restricts movement across cell membranes, resulting in less
accumulation of Pb in fish in comparison to other metals (e.g., Hg, Cu) (Baatrup, 1991).
The accumulation of Pb in aquatic organisms is, therefore, influenced by water pH, with
lower pHs favoring bioavailability and accumulation. For example, fish accumulated Pb at a
greater rate in acidic lakes (pH = 4.9 to 5.4) than in more neutral lakes (pH = 5.8 to 6.8) (Stripp
et al., 1990). Merlini and Pozzi (1977) found that pumpkinseed sunfish exposed to Pb at pH 6.0
accumulated three-times as much Pb as fish kept at pH 7.5. However, Albers and Camardese
(1993a,b) examined the effects of pH on Pb uptake in aquatic plants and invertebrates in acidic
(pH -5.0) and nonacidic (pH -6.5) constructed wetlands, ponds, and small lakes in Maine and
Maryland. Their results suggested that low pH had little effect on the accumulation of metals by
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aquatic plants and insects and on the concentration of metals in the waters of these aquatic
systems (Albers and Camardese, 1993a,b).
Three geochemical factors that influence metal bioaccumulation in aquatic organisms
include speciation, particulate metal form, and metal form in the tissues of prey items (Luoma
and Rainbow, 2005). Lead is typically present in acidic aquatic environments as PbSC>4, PbCU,
ionic Pb, cationic forms of Pb-hydroxide, and ordinary hydroxide Pb(OH)2. In alkaline waters,
common species of Pb include anionic forms of Pb-carbonate (Pb(CC>3)) and Pb(OH)2. Labile
forms of Pb (e.g., Pb2+, PbOH+, PbCOs) are a significant portion of the Pb inputs to aquatic
systems from atmospheric washout. Particulate-bound forms are more often linked to urban
runoff and mining effluents (Eisler, 2000). Little research has been done to link the complex
concepts of chemical speciation and bioavailability in natural systems (Vink, 2002). The
relationship between the geochemistry of the underlying sediment and the impact of temporal
changes (e.g., seasonal temperatures) to metal speciation are particularly not well studied (Vink,
2002; Hassler et al., 2004).
Generally speaking, aquatic organisms exhibit three Pb accumulation strategies:
(1) accumulation of significant Pb concentrations with a low rate of loss, (2) excretion of Pb
roughly in balance with availability of metal in the environment, and (3) weak net accumulation
due to very low metal uptake rate and no significant excretion (Rainbow, 1996). Species that
accumulate nonessential metals such as Pb and that have low rates of loss must partition it
internally in such a way that it is sparingly available metabolically. Otherwise, it may cause
adverse toxicological effects (Rainbow, 1996). Aquatic organisms that exhibit this type of
physiological response have been recommended for use both as environmental indicators of
heavy metal pollution (Borgmann et al., 1993; Castro et al., 1996; Carter and Porter, 1997) and,
in the case of macrophytes, as phytoremediators, because they accumulate heavy metals rapidly
from surface water and sediment (Gavrilenko and Zolotukhina, 1989; Simoes Gon9alves et al.,
1991; Carter and Porter, 1997).
Uptake experiments with aquatic plants and invertebrates (e.g., macrophytes,
chironomids, crayfish) have shown steady increases in Pb uptake with increasing Pb
concentration in solution (Knowlton et al., 1983; Timmermans et al., 1992). In crayfish, the
process of molting can cause a reduction in body Pb concentrations, as Pb incorporated into the
crayfish shell is eliminated (Knowlton et al., 1983). Vazquez et al. (1999) reported on the uptake
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of Pb from solution to the extracellular and intracellular compartments of 3 species of aquatic
bryophytes. Relative to the 6 metals tested, Pb was found to accumulate to the largest degree in
the extracellular compartments of all 3 bryophytes. The extracellular metals were defined as
those that are incorporated into the cell wall or are found on the outer surface of the plasma
membrane (i.e., adsorbed) (Vazquez et al., 1999). Intracellular metals were defined as metals
introduced into the cell through a metabolically controlled process.
Arai et al. (2002) examined the effect of growth on the uptake and elimination of trace
metals in the abalone Haliotos. They reported that older abalones had generally lower whole
body concentrations of heavy metals than did younger, rapidly growing individuals. During the
rapid growth of juveniles, the organism is less able to distinguish between essential (e.g., Zn),
and nonessential metals (e.g., Pb). Once they reach maturity, they develop the ability to
differentiate these metals. Li et al. (2004) reported a similar response in zebra fish embryo-
larvae. Li et al. (2004) suggested that mature physiological systems are not developed in the
embryo-larvae to handle elevated concentrations of metals. Therefore, metals are transported
into the body by facilitated diffusion. Both the zebra fish and juvenile abalone demonstrate a
rapid accumulation strategy followed by a low rate of loss as described above. There are
insufficient data available to determine whether this phenomenon is true for other aquatic
organisms.
Growth rates are generally thought to be an important consideration in the comparison of
Pb levels in individuals of the same species. The larger the individual the more the metal content
is diluted by body tissue (Rainbow, 1996).
Once Pb is absorbed, it may sequester into varying parts of the organism. Calcium
appears to have an important influence on Pb transfer. For example, Pb uptake and retention in
the skin and skeleton of coho salmon was reduced when dietary Ca was increased (Varanasi and
Gmur, 1978). Organic Pb compounds tend to accumulate in lipids, and are taken up and
accumulated in fish more readily than inorganic Pb compounds (Pattee and Pain, 2003).
Given the complexities of metal uptake in natural systems, a model incorporating some of
the factors mentioned above is desirable. The EPA's Environmental Research Laboratory in
Duluth, Minnesota developed a thermodynamic equilibrium model, MINTEQ that predicts
aqueous speciation, adsorption, precipitation, and/or dissolution of solids for a defined set of
environmental conditions (MacDonald et al., 2002; Playle, 2004). Although not specifically
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designed to model uptake, MINTEQ provides an indication of what forms of the metal are likely
to be encountered by aquatic organisms by estimating the formation of metal ions, complexation
of metals, and the general bioavailability of metals from environmental parameters. More
recently, a mechanistic model centered on biodynamics has been proposed by Luoma and
Rainbow (2005) as a method of tying together geochemical influences, biological differences,
and differences among metals to model metal bioaccumulation. The biodynamic model would
be useful in determining the potential adverse effects on aquatic biota, which species are most
useful as indicators of metal effects, and how ecosystems may change when contaminated by
metals. Two prominent models examine trace metal bioavailability and its link to effects
(Hassler et al., 2004). These include the free ion activity model (FIAM) and the biotic ligand
model (BLM). Specific information on these models, including their limitations, is provided in
Section AX7.2.1.3. These models are useful for advancing our understanding of how metal
uptake occurs in aquatic organisms and how uptake and toxic effects are linked.
Bioconcentration Factors (BCF)
BCFs for Pb are reported for various aquatic plants in Table AX7-2.3.1. The green alga
Cladophora glomerata is reported as having the highest BCF (Keeney et al., 1976). Duckweed
(Lemna minor) exhibited high BCF values ranging from 840 to 3560 depending on the method of
measurement (Rahmani and Sternberg, 1999). Duckweed that was either previously exposed or
not exposed to Pb was exposed to a single dose of Pb-nitrate at 5000 |ig/L for 21 days.
Duckweed that was previously exposed to Pb removed 70 to 80% of the Pb from the water, while
the previously unexposed duckweed removed 85 to 90%. Both plant groups were effective at
removing Pb from the water at sublethal levels.
BCFs for Pb are reported for various invertebrates in Table AX7-2.3.2. BCFs for
freshwater snails were 738 for a 28-day exposure (Spehar et al., 1978) and 1,700 for a 120-day
exposure (Borgmann et al., 1978). Other reported values for invertebrates included a BCF of
1930 for the scud during a 4-day exposure (MacLean et al., 1996), and BCFs of 499 and 1120 for
the caddis fly and stonefly, respectively, in 28-day exposures (Spehar et al., 1978). In a 28-day
exposure, midge larvae were reported with a BCF of 3670 (Timmermans et al., 1992).
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Table AX7-2.3.1. Bioconcentration Factors for Aquatic Plants
BCF
840 to 2700
(measured digestion)
Species
Duckweed
(Lemna minor)
Test Conditions
21 days, Pb-nitrate
Reference
Rahmani and Sternberg
(1999)
1150 to 3560
(measured solution)
16,000 to 20,000
Duckweed
Alga (Cladophora
glomerata)
21 days, Pb-nitrate Rahmani and Sternberg
(1999)
not specified
Keeneyetal. (1976)
BCF
Table AX7-2.3.2. Bioconcentration Factors for Aquatic Invertebrates
Species
Test Conditions
Reference
738
1700
499
1120
1930
3670
Snail (Physa Integra)
Snail (Lymnaea palustris)
Caddis fly (Brachycentrus sp.)
Stonefly (Pteronarcys dorsatd)
Scud (Hyalella azteca)
28 days, Pb-nitrate Spehar et al. (1978)
120 days, Pb-nitrate Borgmann et al. (1978)
28 days, Pb-nitrate Spehar et al. (1978)
28 days, Pb-nitrate Spehar et al. (1978)
4 days, Pb-chloride MacLean et al. (1996)
Midge larvae (Chironomus rlpanus) 28 days
Timmermans et al. (1992)
BCFs for freshwater fish were 42 and 45 for brook trout and bluegill, respectively
(Holcombe et al., 1976; Atchison et al., 1977). Although no BCFs have been reported for
amphibians, Pb-nitrate was reported to accumulate mainly in the ventral skin and in the kidneys
of frogs (Vogiatzis and Loumbourdis, 1999).
Bioconcentration factors and bioaccumulation factors (BAFs) are not necessarily the best
predictors of tissue concentration levels given exposure concentration levels (Kapustka et al.,
2004). The role of homeostatic mechanisms is a major consideration in tissue concentrations
found in exposed biota. Similarly, measuring BCFs and BAFs in organisms may not accurately
reflect how metals are treated within the organisms (e.g., partitioning to specific organelles,
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sequestering to organ tissues). Therefore, they are not recommended for use in conducting metal
risk assessments (Kapustka et al., 2004).
AX7.2.3.2 Resistance Mechanisms
Detoxification Mechanisms
Detoxification includes the biological processes by which the toxic qualities, or the
probability and/or severity of harmful effects, of a poison or toxin are reduced by the organism.
In the case of heavy metals, this process frequently involves the sequestration of the metal,
rendering it metabolically inactive. Recent research into heavy metal detoxification in aquatic
biota has focused on several physiological and biochemical mechanisms for detoxifying Pb.
This section examines these mechanisms and the ability of plants, protists, invertebrates, and fish
to mitigate Pb toxicity.
Plants and Protists
Deng et al. (2004) studied the uptake and translocation of Pb in wetland plant species
surviving in contaminated sites. They found that all plants tended to sequester significantly
larger amounts of Pb in their roots than in their shoots. Deng et al. (2004) calculated a
translocation factor (TF), the amount of Pb found in the shoots divided by the amount of Pb
found in the root system, and found that TFs ranged from 0.02 to 0.80. Concentrations of Pb in
shoots were maintained at low levels and varied within a narrow range. Deng et al. (2004)
observed that plants grown in Pb-contaminated sites usually contained higher concentrations
than the 27 mg/kg toxicity threshold established for plants by Beckett and Davis (1977). Some
of the wetland plants examined by Deng et al. (2004) also accumulated high concentrations of
metals in shoot tissues; however, these metals were assumed to be detoxified (metabolically
unavailable), as no toxic response to these elevated concentrations was observed. Deng et al.
(2004) suggested that this ability is likely related to discrete internal metal detoxification
tolerance mechanisms.
Phytochelatins are thiol-containing intracellular metal-binding polypeptides that are
produced by plants and protists in response to excessive uptake of heavy metals (Zenk, 1996).
Phytochelatins are synthesized by the enzyme phytochelatin synthase that is activated by the
presence of metal ions and uses glutathione as a substrate. When phytochelatins are synthesized
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in sufficient amounts to chelate the metal ion, the enzyme is deactivated (Morelli and Scarano,
2001).
Morelli and Scarano (2001) studied phytochelatin synthesis and stability in the marine
diatom Phaeodactylum tricormitum in the presence of Pb. They found that when metal exposure
was alleviated, significant cellular Pb-phytochelatin complex content was lost. Their findings
support a hypothesis of vacuolarization proposed for higher plants (Zenk, 1996), in which metal -
phytochelatin complexes are actively transported from the cytosol to the vacuole, where they
undergo rapid turnover. Zenk (1996) suggested that the complex dissociates, and the metal-free
peptide is subsequently degraded. Morelli and Scarano (2001) proposed concomitant occurrence
of phytochelatin synthesis and release during metal exposure, as a coincident detoxification
mechanism in P. tricornutum.
Aquatic Invertebrates
Like plants and protists, aquatic animals detoxify Pb by preventing it from being
metabolically available, though their mechanisms for doing so vary. Invertebrates use
lysosomal-vacuolar systems to sequester and process Pb within glandular cells (Giamberini and
Pihan, 1996). They also accumulate Pb as deposits on and within skeletal tissue (Knowlton
et al., 1983; Anderson et al., 1997; Boisson et al., 2002), and some can efficiently excrete Pb
(Vogt and Quinitio, 1994; Prasuna et al., 1996).
Boisson et al. (2002) used radiotracers to evaluate the transfer of Pb into the food pathway
of the starfish Asterias rubens as well as its distribution and retention in various body
compartments. Boisson et al. (2002) monitored Pb elimination after a single feeding of Pb-
contaminated molluscs and found that Pb was sequestered and retained in the skeleton of the
starfish, preventing it from being metabolically available in other tissues. Elimination (as
percent retention in the skeleton) was found to follow an exponential time course. Elimination
was rapid at first, but slowed after 1 week, and eventually stabilized, implying an infinite
biological half-life for firmly bound Pb. Results of radiotracer tracking suggest that Pb migrates
within the body wall from the organic matrix to the calcified skeleton. From there, the metal is
either absorbed directly or adsorbed on newly produced ossicles (small calcareous skeletal
structures), where it is efficiently retained as mineral deposition and is not metabolically active
(Boisson et al., 2002).
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AbdAllah and Moustafa (2002) studied the Pb storage capability of organs in the marine
snail Nerita saxtilis. Enlarged electron-dense vesicles and many granules were observed in
digestive cells of these snails and are suggested to be the site of storage of detoxified metals.
N. saxtilis were found to be capable of concentrating Pb up to 50 times that of surrounding
marine water without exhibiting signs of histopathologic changes. This ability has been
attributed to chelation with various biochemical compounds, such as thionine (forming
metallothionine) (Rainbow, 1996), or complexation with carbonate, forming lipofuchsin
(AbdAllah and Moustafa, 2002). Granules observed in lysosomal residual bodies were presumed
to be the result of Pb accumulation. The presence of large vacuoles and residual bodies were
indicative of the fragmentation phase of digestion, suggesting that Pb was also processed
chemically in the digestive cells.
The podocyte cells of the pericardial gland of bivalves are involved in the ultrafiltration of
the hemolymph (Giamberini and Pihan, 1996). A microanalytical study of the podocytes in
Dreissenapolymorpha exposed to Pb revealed lysosomal-vacuolar storage/processing similar to
that in the digestive cells of Nerita saxtilis. The lysosome is thought to be the target organelle
for trace metal accumulation in various organs of bivalves (Giamberini and Pihan, 1996).
Epithelial secretion is the principal detoxification mechanism of the tiger prawn Penaeus
monodon. Vogt and Quinitio (1994) found that Pb granules tended to accumulate in the
epithelial cells of the antennal gland (the organ of excretion) of juveniles exposed for 5 and
10 days to waterborne Pb. The metal is deposited in vacuoles belonging to the lysosomal
system. Continued deposition leads to the formation of electron-dense granules. Mature
granules are released from the cells by apocrine secretion into the lumen of the gland, and
presumably excreted through the nephridopore (i.e., the opening of the antennal gland).
Apocrine secretion is predominant, so that as granules form, they are kept at low levels.
Excretion was also found to be a primary and efficient detoxification mechanism in the shrimp
Chrissia halyi (Prasuna et al., 1996).
Crayfish exposed to Pb have been shown to concentrate the metal in their exoskeleton and
exuvia through adsorption processes. More than 80% of Pb found in exposed crayfish has been
found in exoskeletons (Knowlton et al., 1983; Anderson et al., 1997). Following exposure,
clearance is most dramatic from the exoskeleton. The result of a 3-week Pb-clearance study with
red swamp crayfish Procambams clarkia, following a 7-week exposure to 150 jig Pb/L, showed
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an 87% clearance from the exoskeleton due, in part, to molting. Other organs or tissues that take
up significant amounts of Pb include the gills, hepatopancreas, muscle, and hemolymph, in
decreasing order. These parts cleared >50% of accumulated Pb over the 3-week clearance
period, with the exception of the hepatopancreas. The hepatopancreas is the organ of metal
storage and detoxification, although the molecular mechanisms of metal balance in crayfish have
yet to be extensively investigated (Anderson et al., 1997).
Fish
Most fish use mucus as a first line of defense against heavy metals (Coello and Khan,
1996). In fish, some epithelia are covered with extracellular mucus secreted from specialized
cells. Mucus contains glycoproteins, and composition varies among species. Mucosal
glycoproteins chelate Pb, and settle, removing the metal from the water column. Fish may
secrete large amounts of mucus when they come into contact with potential chemical and
biochemical threats. Coello and Khan (1996) investigated the role of externally added fish
mucus and scales in accumulating Pb from water, and the relationship of these with the toxicity
of Pb in fmgerlings of green sunfish, goldfish and largemouth bass. The authors compared trials
in which fish scales from black sea bass (Centropristis striatd) and flounder (Pseudopleuronectes
americanus) and mucus from largemouth bass were added to green sunfish, goldfish, and
largemouth bass test systems and to reference test systems. On exposure to Pb, fish immediately
started secreting mucus from epidermal cells in various parts of the body. Metallic Pb stimulated
filamentous secretion, mostly from the ventrolateral areas of the gills, while Pb-nitrate stimulated
diffuse molecular mucus secretion from all over the body. The addition of largemouth bass
mucus significantly increased the LTso (the time to kill 50%) for green sunfish and goldfish
exposed to 250 mg/L of Pb-nitrate. In contrast, Tao et al. (2000) found that mucus reduced the
overall bioavailability of Pb to fish but that the reduction was insignificant. Coello and Khan
(1996) found that scales were more significant in reducing LT50 than mucous. Fish scales can
accumulate high concentrations of metals, including Pb, through chelation with keratin. Scales
were shown to buffer the pH of Pb-nitrate in solution and remove Pb from water after which they
settled out of the water column. Addition of scales to test water made all species (green sunfish,
goldfish, and largemouth bass) more tolerant of Pb.
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Summary of Detoxi fiction Processes
Mechanisms of detoxification vary among aquatic biota and include processes such as
translocation, excretion, chelation, adsorption, vacuolar storage, and deposition. Lead
detoxification has not been studied extensively in aquatic organisms, but existing results indicate
the following:
• Protists and plants produce intracellular polypeptides that form complexes with Pb (Zenk,
1996; Morelli and Scarano, 2001).
• Macrophytes and wetland plants that thrive in Pb-contaminated regions have developed
translocation strategies for tolerance and detoxification (Knowlton et al., 1983; Deng et al.,
2004).
• Some starfish (asteroids) sequester the metal via mineral deposition into the exoskeleton
(Boisson et al., 2002).
• Species of mollusc employ lysosomal-vacuolar systems that store and chemically process Pb
in the cells of their digestive and pericardial glands (Giamberini and Pihan, 1996; AbdAllah
and Moustafa, 2002).
• Decapods can efficiently excrete Pb (Vogt and Quinitio, 1994; Giamberini and Pihan, 1996)
and sequester metal through adsorption to the exoskeleton (Knowlton et al., 1983).
• Fish scales and mucous chelate Pb in the water column, and potentially reduce visceral
exposure.
Avoidance Response
Avoidance is the evasion of a perceived threat. Recent research into heavy metal
avoidance in aquatic organisms has looked at dose-response relationships as well as the effects of
coincident environmental factors. Preference/avoidance response to Pb has not been extensively
studied in aquatic organisms. In particular, data for aquatic invertebrates is lacking.
Using recent literature, this section examines preference-avoidance responses of
invertebrates and fish to Pb and some other environmental gradients.
Aquatic Invertebrates
Only one study was identified on avoidance response in aquatic invertebrates. Lefcort
et al. (2004) studied the avoidance behavior of the aquatic pulmonate snail Physella columbiana
from a pond that had been polluted with heavy metals for over 120 years. In a Y-maze test, first
generation P. columbiana from the contaminated site avoided Pb at 9283 |ig/L (p < 0.05) and
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moved toward Pb at 6255 jig/L (p < 0.05). It is thought that attraction to Pb at certain elevated
concentrations is related to Pb neuron-stimulating properties (Lefcort et al., 2004). These results
are consistent with those from similar studies. Control snails from reference sites, and first and
second-generation snails from contaminated sites were capable of detecting and avoiding heavy
metals, although the first generation was better than the second generation, and the second was
better than the controls at doing so. This suggests that detection and avoidance of Pb is both
genetic and environmentally based for P. columbiana. Lefcort et al. (2004) observed heightened
sensitivity to, and avoidance of, heavy metals by the snails when metals where present in
combination.
Aquatic Vertebrates
Steele et al. (1989) studied the preference-avoidance response of bullfrog (Rana
catesbeiand) to plumes of Pb-contaminated water following 144-h exposure to 0 to 1000 jig
Pb/L. In this laboratory experiment, tadpoles were exposed to an influx of 1000 jig Pb/L at five
different infusion rates (i.e., volumes per unit time into the test system). Experiments were
videotaped and location data from the tank were used to assess response. No significant
differences were seen in preference-avoidance responses to Pb in either nonexposed or
previously exposed animals. In a similar subsequent study, Steele et al. (1991) studied
preference-avoidance response to Pb in American toad (Bufo americanus) using the same
exposure range (0 to 1000 jig Pb/L). B. americanus did not significantly avoid Pb, and
behavioral stress responses were not observed. The results do not indicate whether the tadpoles
were capable of perceiving the contaminant. Lack of avoidance may indicate insufficient
perception or the lack of physiological stress (Steele et al., 1991).
The olfactory system in fish is involved in their forming avoidance response to heavy
metals (Brown et al., 1982; Svecevicius, 1991). It is generally thought that behavioral avoidance
of contaminants may be a cause of reduced fish populations in some water bodies, because of
disturbances in migration and distribution patterns (Svecevicius, 2001). Unfortunately,
avoidance of Pb by fish has not been studied as extensively as for other heavy metals
(Woodward et al., 1995).
Woodward et al. (1995) studied metal mixture avoidance response in brown trout
(Salmo trutta), as well as the added effects of acidification. A 1-fold (1H) mixture contained
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1.1 ng/L Cd, 12 |ig/L Cu, 55 |ig/L Zn, and 3.2 |ig/L Pb (all metals were in the form of chlorides).
Avoidance was quantified as time spent in test water, trip time to test water, and number of trips.
Brown trout avoided the 1H mixture as well as the 0.5H, 2H, 4H, and 10H mixtures, but not the
0.1H mixture. Reduced avoidance was observed at higher concentrations (4H and 10H). The
authors proposed that the reduced avoidance response was due to impaired perception due to
injury. These responses are typical of other fish species to individual metals of similar
concentrations (Woodward et al., 1995). This study does not conclusively indicate which of the
metals in the mixture may be causing the avoidance response. However, given the neurotoxic
effects of Pb, impaired perception is a likely response of Pb-exposed fish.
When test water was reduced in pH from 8 to 7, 6 to 5, brown trout avoidance increased,
but with no significant difference between metal treatments and controls. However, in the 1H
metal mixture treatment, brown trout made fewer trips into the test water chamber at the lower
pHs (Woodward et al., 1995). This response may be related to an increased abundance of Pb
cations at lower pH values in the test system.
Scherer and McNicol (1998) investigated the preference-avoidance responses of lake
whitefish (Coregonus clupeaformis) to overlapping gradients of light and Pb. Whitefish were
found to prefer shade in untreated water. Lead concentrations under illumination ranged from
0 to 1000 |ig/L, and from 0 to 54,000 |ig/L in the shade. Under uniform illumination, Pb was
avoided at concentrations above 10 |ig/L, but avoidance behavior lacked a dose-dependent
increase over concentrations ranging from 10 to 1000 jig Pb/L. Avoidance in shaded areas was
strongly suppressed, and whitefish only avoided Pb at concentrations at or above 32,000 |ig/L.
Summary of Avoidance Response
In summary, of those aquatic organisms studied, some are quite adept at avoiding Pb in
aquatic systems, while others seem incapable of detecting its presence. Snails have been shown
to be sensitive to Pb and to avoid it at high concentrations. Conversely, anuran (frog and toad)
species lack an avoidance response to the metal. Fish avoidance of many chemical toxicants has
been well established, and it is a dominant sublethal response in polluted waters (Svecevicius,
2001). However, no studies have been located specifically examining avoidance behavior for Pb
in fish. Environmental gradients, such as light and pH, can alter preference-avoidance responses.
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AX7.2.3.3 Physiological Effects of Lead
This section presents a review of the physiological effects and functional growth
responses associated with the exposure of aquatic biota to Pb. Physiological effects of Pb on
aquatic biota can occur at the biochemical, cellular, and tissue levels of organization and include
inhibition of heme formation, adverse effects to blood chemistry, and decreases in enzyme
levels. Functional growth responses resulting from Pb exposure include changes in growth
patterns, gill binding affinities, and absorption rates.
Biochemical Effects
Lead was observed to have a gender-selective effect on brain endocannabinoid (eCB)
(e.g., 2-arachidonylglycerol [2-AG] and jV-arachidonylethanolamine [AEA]) levels in fathead
minnow Pimephalespromelas (Rademacher et al., 2005). Cannabinoids, such as eCB, influence
locomotor activity in organisms. Increased levels of cannabinoids have been shown to stimulate
locomotor activity and decreased levels slow locomotor activity (Safiudo-Pefia et al., 2000).
Male and female fathead minnows were exposed to 0 and 1000 |ig/L of Pb. Female minnows in
the control group contained significantly higher levels of AEA and 2-AG compared to males.
At a concentration of 1000 jig Pb/L, this pattern reversed, with males showing significantly
higher levels of AEA in the brain than females (Rademacher et al., 2005). After 14-days
exposure to the 1000 jig Pb/L treatment, significantly higher levels of 2-AG were found in male
fathead minnows, but no effect on 2-AG levels in females was observed (Rademacher et al.,
2005).
Lead acetate slightly inhibited 7-ethoxyresorufin-o-deethylase (7-EROD) activity in
Gammaruspulex exposed for up to 96 h to a single toxicant concentration (EC50) (Kutlu and
Susuz, 2004). The exact concentration used in the study was not reported. The EROD enzyme
is required to catalyze the conjugation and detoxification of toxic molecules and has been
proposed as a biomarker for contaminant exposure. The authors believe more detailed studies
are required to confirm EROD as a biomarker for Pb exposure. The enzyme group alanine
transferases (ALT) has been suggested as a bioindicator/biomarker of Pb stress (Blasco and
Puppo, 1999). A negative correlation was observed between Pb accumulation and ALT
concentrations in the gills and soft body of Ruditapesphilippinarum exposed to 350 to 700 |ig/L
of Pb for 7 days (Blasco and Puppo, 1999).
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Studies have identified ALAD in fish and amphibians as a useful indicator of Pb exposure
(Gill et al., 1991; Nakagawa et al., 1995a,b). ALAD catalyzes the formation of hemoglobin and
early steps in the synthesis of protoporphyrin (Gill et al., 1991; Nakagawa et al., 1995b). The
absence of an inhibitory effect on this enzyme following exposure to cadmium, copper, zinc, and
mercury suggests that this enzyme reacts specifically to Pb (Johansson-Sjobeck and Larsson,
1979; Gill et al., 1991). A 0% decrease in ALAD activity was reported in common carp
(Cyprinus carpio) exposed to a Pb concentration of 10 |ig/L for 20 days (Nakagawa et al.,
1995b). The recovery of ALAD activity after exposure to Pb has also been examined in carp
(Nakagawa et al., 1995a). After 2-week exposure to 200 jig Pb/L, ALAD activity decreased to
approximately 25% of value reported for controls (Nakagawa et al., 1995a). Fish removed from
the test concentration after 2 weeks and placed in a Pb-free environment recovered slightly, but
ALAD activity was only 50% of the controls even after 4 weeks (Nakagawa et al., 1995a).
Vogiatzis and Loumbourdis (1999) exposed the frog (Rana ridibundd) to a Pb concentration of
14,000 |ig/L over 30 days and a 90% decrease in ALAD activity was observed in the frogs.
Blood Chemistry
Numerous studies have examined the effects of Pb exposure on blood chemistry in aquatic
biota. These studies have primarily used fish in acute and chronic exposures to Pb
concentrations ranging from 100 to 10,000 |ig/L. Decreased erythrocyte, hemoglobin, and
hemocrit levels were observed in rosy barb (Barbuspuntius) during an 8-week exposure to
126 |ig/L of Pb-nitrate (Gill et al., 1991).
No difference was found in red blood cell counts and blood hemoglobin in yellow eels
{Anguilla anguilla) exposed to 0 and 300 |ig/L of Pb for 30 days (Santos and Hall, 1990). The
number of white blood cells, in the form of lymphocytes, increased in the exposed eels. The
authors concluded this demonstrates the lasting action of Pb as a toxicant on the immune system
(Santos and Hall, 1990). Significant decreases in red blood cell counts and volume was reported
in blue tilapia (Oreochromis aureus) exposed to Pb-chloride at a concentration of 10,000 |ig/L
for 1 week (Allen, 1993).
Blood components, such as plasma glucose, total plasma protein, and total plasma
cholesterol, were unaffected in yellow eels exposed to 300 |ig/L of Pb for 30 days (Santos and
Hall, 1990). Effects on plasma chemistry were observed in Oreochromis mossambicus exposed
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to 0, 18,000, 24,000, and 33,000 |ig/L of Pb (Ruparelia et al., 1989). Significant decreases in
plasma glucose (hypoglycemic levels) were reported at concentrations of 24,000 and 33,000 Og
Pb/L after 14 and 21 days of exposure, and at 18,000 jig Pb/L after 21 days of exposure
(Ruparelia et al., 1989). Plasma cholesterol levels dropped significantly in comparison to
controls after 14 days of exposure to 33,000 jig Pb/L and in all test concentrations after 21 days
of exposure (Ruparelia et al., 1989). Similarly, concentrations of blood serum protein, albumin,
and globulin were identified as bioindicators of Pb stress in carp (Cyprinus carpio) exposed to
Pb-nitrates at concentrations of 800 and 8000 |ig Pb/L (Gopal et al., 1997).
Tissues
In fish, the gills serve as an active site for ion uptake. Recent studies have examined the
competition between cations for binding sites at the fish gill (e.g., Ca2+, Mg2+, Na+, H+, Pb2+)
(MacDonald et al., 2002; Rogers and Wood, 2003, 2004). Studies suggest that Pb2+ is an
antagonist of Ca2+ uptake (Rogers and Wood, 2003, 2004). MacDonald et al. (2002) proposed a
gill-Pb binding model that assumes Pb2+ has a 3100 times greater affinity for binding sites at the
fish gill than other cations. More toxicity studies are required to quantify critical Pb burdens that
could be used as indicators of Pb toxicity (Niyogi and Wood, 2003).
Growth Responses
A negative linear relationship was observed in the marine gastropod abalone (Haliotis)
between shell length and muscle Pb concentrations (Arai et al., 2002). Abalones were collected
from two sites along the Japanese coast. Haliotis discus hannai were collected from along the
coast at Onagawa; Haliotis discus were collected from along the coast at Amatsu Kominato. The
authors did not report significant differences between the two sampling sites. From samples
collected at Onagawa, Pb concentrations of 0.03 and 0.01 jig/g were associated with abalone
shell lengths of 7.7 cm (3 years old) and 12.3 cm (6 years old), respectively. From samples
collected at Amatsu Kominato, Pb concentrations of 0.09 and 0.01 jig/g were associated with
abalone shell lengths of 3.9 cm (0 years old) and 15.3 cm (8 years old), respectively (Arai et al.,
2002). The authors theorized that young abalones, experiencing rapid growth, do not
discriminate between the uptake of essential and nonessential metals. However, as abalones
grow larger and their rate of growth decreases, they increasingly favor the uptake of essential
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metals over nonessential metals. This is demonstrated by the relatively consistent concentrations
of Cu, Mn, and Zn that were reported for the abalone samples (Arai et al., 2002).
Other Physiological Effects
Increased levels of Pb in water were found to increase fish production of mucus: excess
mucus coagulates were observed over the entire body of fishes. Buildup was particularly high
around the gills, and in the worst cases, interfered with respiration and resulted in death by
anoxia (Aronson, 1971; National Research Council of Canada., 1973).
AX7.2.3.4 Factors That Modify Organism Response to Lead
A great deal of research has been undertaken recently to better understand the factors that
modify aquatic organism response to metals including lead. A discussion of research on the
many factors that can modify aquatic organism response to Pb is provided in this section.
Influence of Organism Age and Size on Lead Uptake and Response
It is generally accepted that Pb accumulation in living organisms is controlled, in part, by
metabolic rates (Farkas et al., 2003). Metabolic rates are, in-turn, controlled by the physiological
conditions of an organism, including such factors as size, age, point in reproductive cycle,
nutrition, and overall health. Of these physiological conditions, size and age are the most
commonly investigated in relation to heavy metal uptake. This section reviews recent research
focusing on relationships between body size, age, and Pb accumulation in aquatic invertebrates
and fish.
Invertebrates
MacLean et al. (1996) investigated bioaccumulation kinetics and toxicity of Pb in the
amphipod Hyalella azteca. Their results indicated that body size did not greatly influence Pb
accumulation in//, azteca exposed to 50 or 100 |ig/L of PbCb for 4 days. Canli and Furness
(1993) found similar results in the Norway lobster Nephrops norvegicus exposed to 100 |ig/L of
Pb(NOs)2 for 30 days. No significant sex- or size-related differences were found in
concentrations of Pb in the tissue. The highest tissue burden was found in the carapaces (42%).
Several studies have determined that Pb can bind to the exoskeleton of invertebrates and
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sometimes dominate the total Pb accumulated (Knowlton et al., 1983). This adsorption of Pb to
the outer surface of invertebrates can result in strong negative relationships for whole-body Pb
concentration as a function of body mass (i.e., concentrations decrease rapidly with increased
body size and then stabilize) (MacLean et al., 1996).
Drava et al. (2004) investigated Pb concentrations in the muscle of red shrimp Aristeus
antennatus from the northwest Mediterranean. Lead concentrations ranged from 0.04 to
0.31 |ig/g dw. No significant relationships between size and Pb concentration in A. antennatus
were found, and concentrations were not related to reproductive status.
Arai et al. (2002) analyzed abalones (Haliotis) at various life stages from coastal regions
of Japan. They investigated growth effects on the uptake and elimination of Pb. Results
indicated a significant negative linear relationship between age, shell length and Pb
concentrations in muscle tissue. The relationship was consistent despite habitat variations in
Pb concentrations between the study sites, suggesting that Pb concentrations changed with
growth in the muscle tissue of test specimens and implying that abalone can mitigate Pb
exposure as they age.
Fish
Douben (1989) investigated the effects of body size and age on Pb body burden in the
stone loach (Noemacheilus barbatulus L.). Fish were caught during two consecutive springs
from three Derbyshire rivers. Results indicated that Pb burden increased slightly with age.
Similarly, Kock et al. (1996) found that concentrations of Pb in the liver and kidneys of Arctic
char (Salvelinus alpinus) taken from oligotrophic alpine lakes were positively correlated with
age. It has been suggested that fish are not able to eliminate Pb completely, and that this leads to
a stepwise accumulation from year to year (Kock et al., 1996). In contrast, Farkas et al. (2003)
found a negative relationship between Pb concentrations and muscle and gill Pb concentrations
in the freshwater fishAbramis brama. Fish were taken from a low-contaminated site and
contained between 0.44 and 3.24 jig/g Pb dw. Negative correlations between metal
concentration and fish size in low-contaminated waters likely results from variations in feeding
rates associated with developmental stages. This hypothesis is consistent with the fact that in
low-contaminated waters, feeding is the main route of uptake and feeding rates decrease with
development in fish (Farkas et al., 2003).
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In summary, relationships between age, size, and Pb body burden in aquatic invertebrates
and fish are interspecifically variable and depend on many environment-related variables (e.g.,
exposure) (Farkas et al., 2003).
Genetics
There are few studies documenting the effects of Pb on organismal and population
genetics, although rapid advances in biotechnology have prompted recent research in this area
(Beaty et al., 1998). There are two principal effects that sublethal exposure to a contaminant can
have on the genetics of an organism and/or population: (1) a contaminant may influence
selection by selecting for certain phenotypes that enable populations to better cope with the
chemical; or (2) a contaminant can be genotoxic, meaning it can produce alterations in nucleic
acids at sublethal exposure concentrations, resulting in changes in hereditary characteristics or
DNA inactivation (Shugart, 1995). Laboratory studies have shown that exposure to Pb2+ at
10 mg/mL in blood produces chromosomal aberrations (i.e., deviations in the normal structure or
number of chromosomes) in some organisms (Cestari et al., 2004). Effects of genotoxicity and
toxin-induced selection do not preclude one another, and may act together on exposed
populations. This section reviews Pb genotoxicity and the effects of Pb-induced selection in
aquatic populations.
Selection
Evidence for genetic selection in the natural environment has been observed in some
aquatic populations exposed to metals (Rand et al., 1995; Beaty et al., 1998; Duan et al., 2000;
Kim et al., 2003). Because tolerant individuals have a selective advantage over vulnerable
individuals in polluted environments, the frequency of tolerance genes will increase in exposed
populations over time (Beaty et al., 1998). Several studies have shown that heavy metals can
alter population gene pools in aquatic invertebrates. These changes have resulted in decreased
genetic diversity and are thought to be a potential source of population instability (Duan et al.,
2000; Kim et al., 2003).
Kim et al. (2003) investigated genetic differences and population structuring in the
gastropod Littorina brevicula from heavy-metal polluted and unpolluted environments.
Organisms from polluted sites contained a mean of 1.76 jig Pb/g, while organisms from
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unpolluted sites contained 0.33 jig Pb/g. They found significant differences in haplotypes
between the test groups and allelic diversity was significantly lower among L. brevicula from
polluted regions. In contrast, Yap et al. (2004) performed a similar experiment with the green-
lipped mussel Perna viridis; they found that mussels from contaminated sites containing between
4 and 10 jig Pb/g, as well as other heavy metals, exhibited a higher percentage of polymorphic
loci and excess heterozygosity compared to those from uncontaminated sites. The higher level
of genetic diversity was attributed to greater environmental heterogeneity (i.e., variation due to
pollution gradients) in contaminated sites (Yap et al., 2004).
Duan et al. (2000) investigated amphipod (Hyalella azteca) selective mortality and
genetic structure following acute exposure to Pb (5.47 mg/L Pb(NC>2)2) as well as exposure to
other heavy metals. They found that genetic differentiation consistently increased among
survivors from the original population, supporting the hypothesis that heavy metals, including
Pb, have the potential to alter the gene pools of aquatic organisms.
Genotoxicity
Lead exposure in water (50 |ig/L) over 4 weeks resulted in DNA strand breakage in the
freshwater mussel Anodonta grandis (Black et al., 1996), although higher concentrations (up to
5000 |ig/L) did not result in significant breakage by the end of the study period. These results
suggest that a threshold effect for DNA damage and repair exists, where DNA repair only occurs
once a certain body exposure level has been reached. More recently, Cestari et al. (2004)
observed similar results in neotropical fish (Hoplias malabaricus) that were fed Pb-contaminated
food over 18, 41, and 64 days. Lead body burdens in H. malabaricus were approximately 21 jig
Pb 2+/g. Results indicated that exposure to Pb significantly increased the frequency of
chromosomal aberrations and DNA damage in kidney cell cultures, although when assessed at
the end of the longer exposure periods, aberrations were less common.
Environmental Biological Factors
Environmental factors that are biological in origin can alter the availability, uptake and
toxicity of Pb to aquatic organisms. These factors can be grouped into living and non-living
constituents. For example, living organisms may sequester Pb from the water column, reducing
the availability and toxicity of the metal in the water column to other biota, thus reducing
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potential toxic effects in other organisms. Non-living organic material (e.g., components of
sloughed-off scales, mucus, carcasses, and other decomposing, humic material) can similarly
combine with Pb from the water column, rendering it unavailable. This section will review the
literature on biological environmental factors and their influence on the bioavailability, uptake,
and toxicity of Pb.
Van Hattum et al. (1996) studied the influence of abiotic variables, including DOC on Pb
concentrations in freshwater isopods (Proasellus meridianus and Asellus aquaticus). They found
that BCFs were significantly negatively correlated with DOC concentrations. Thus, as DOC
concentrations increased, BCFs decreased in P. meridianus and A. aquaticus., indicating that
DOC acts to inhibit the availability of Pb to these isopods.
Kruatrachue et al. (2002) investigated the combined effects of Pb and humic acid on total
chlorophyll content, growth rate, multiplication rate, and Pb uptake of common duckweed.
When humic acid was added to the Pb-nitrate test solutions (50, 100, and 200 mg Pb(NO3)2/ L),
toxicity of Pb to duckweed was decreased. The addition of humic acid to the Pb-nitrate solution
increased the pH. The authors suggested that there was a proton dissociation from the carboxyl
group in the humic acid that complexed with Pb, resulting in a decrease in free Pb ions available
to the plant.
Schwartz et al. (2004) collected natural organic matter (NOM) from several aquatic sites
across Canada and investigated the effects of NOM on Pb toxicity in rainbow trout
(Oncorhynchus mykiss). They also looked at toxicity effects as they related to the optical
properties of the various NOM samples. The results showed that NOM in test water almost
always increased LTso and that optically dark NOM tended to decrease Pb toxicity more than did
optically light NOM in rainbow trout.
In summary, non-living constituents of biological origin in the environment have been
shown to reduce Pb availability and, therefore, toxicity in some aquatic organisms. It is
generally thought that this occurs through complexation or chelation processes that take place in
the water column.
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Physicochemical Environmental Factors
This section reviews the literature on physicochemical environmental factors and their
influence on the bioavailability, uptake, and toxicity of Pb in aquatic organisms. These factors
are discussed with regard to their influence individually and in combination.
Studies generally agree that as pH increases, the toxicity of Pb decreases (Home and
Dunson, 1995b; MacDonald et al., 2002). As pH decreases, Pb becomes more soluble and more
readily bioavailable to aquatic organisms (Weber, 1993). Significantly lower survival, decreased
hatching success, slower development, and increased egg mass and larval mortality were
observed in Jefferson salamanders (Ambystomajeffersonianum) and wood frogs (Rana sylvatica)
exposed to Pb at a pH of 4.5 versus a pH of 5.5 (Home and Dunson, 1995b). Contradictory
results have been reported for invertebrates. Over a 96-h exposure period, mortality increased
with decreasing pH for the bivalve Pisidium casertamtm, while pH-independent mortality was
reported for gastropods and Crustacea under similar exposure conditions (Mackie, 1989).
Cladocerans (C. dubid) and amphipods (H. azteca) were also more sensitive to Pb toxicity at pH
6 to 6.5 than at higher pH levels (Schubauer-Berigan et al., 1993). Lead was 100 times more
toxic to the amphipod Hyalella azteca at a pH range of 5.0 to 6.0 (Mackie, 1989) than at a pH
range of 7.0 to 8.5 (Schubauer-Berigan et al., 1993). Lead was also more toxic to fathead
minnows at lower pH levels (Schubauer-Berigan et al., 1993).
The influence of pH on Pb accumulation has also been observed in sediments.
Accumulation of Pb by the isopod Asellus communis was enhanced at low pH, after a 20-day
exposure to Pb-contaminated sediments (Lewis and Mclntosh, 1986). In A. aquations,
temperature increases were found to be more important than increased pH in influencing Pb
accumulation (Van Hattum et al., 1996). Increased water temperature was also found to reduce
Pb uptake fluxes in green microalga (Chlorella kesslerii) (Hassler et al., 2004). Lead and zinc
body concentrations in Asellus sp. were found to vary markedly with seasonal temperature
changes, with greater concentrations present in spring and summer (Van Hattum et al., 1996).
Acute and chronic toxicity of Pb increases with decreasing water hardness, as Pb becomes
more soluble and bioavailable to aquatic organisms (Home and Dunson, 1995a; Borgmann et al.,
2005). There is some evidence that water hardness and pH work together to increase or decrease
the toxicity of Pb. Jefferson salamanders exposed to Pb for 28 days at low pH and low water
hardness experienced 50% mortality, while exposure to Pb at high pH and high water hardness
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resulted in 91.7% survival (Home and Dunson, 1995a). Exposure to Pb at high pH and low
water hardness or low pH and high water hardness resulted in 75 and 41.7% survival,
respectively (Home and Dunson, 1995a). Similar results were reported for Jefferson
salamanders during a 7-day exposure and wood frogs during 7- and 28-day exposures (Home
and Dunson, 1995c). In some cases, water hardness and pH in the absence of Pb have been
shown to affect survival adversely. Mean acute survival of wood frogs and Jefferson
salamanders exposed to low pH and low water hardness, in the absence of Pb, was 83.3 and
91.7%, respectively. Mean chronic survival of wood frogs and Jefferson salamanders exposed to
low pH and low water hardness, in the absence of Pb, was 79.2 and 41.7%, respectively (Home
and Dunson, 1995c).
High Ca2+ concentrations have been shown to protect against the toxic effects of Pb
(Sayer et al., 1989; MacDonald et al., 2002; Hassler et al., 2004; Rogers and Wood, 2004).
Calcium affects the permeability and integrity of cell membranes and intracellular contents
(Sayer et al., 1989). As Ca2+ concentrations decrease, the passive flux of ions (e.g., Pb) and
water increases. At the lowest waterborne Ca2+ concentration (150 jimol/L), Pb accumulation in
juvenile rainbow trout (Oncorhynchus mykiss) branchials significantly increased as Pb
concentration in water increased (Rogers and Wood, 2004). At higher Ca2+ concentrations, Pb
accumulation did not significantly increase with Pb concentration in water. This result
demonstrates the protective effects of waterborne Ca2+ and supports the suggestion that the Ca2+
component of water hardness determines the toxicity of Pb to fish (Rogers and Wood, 2004).
Rogers and Wood (2004) reported that the uptake of Ca2+ and Pb2+ involves competitive
inhibition of apical entry at lanthanum-sensitive Ca2+ channels and interference with the function
of the ATP-driven baso-lateral Ca2+pump. High mortality was reported in brown trout (Salmo
trutta) fry exposed to Pb at a waterborne Ca2+ concentration of 20 |imol/L, while negligible
mortality was reported at the same Pb concentration but at a waterborne Ca2+ concentration of
200 jimol/L (Sayer et al., 1989). Adverse effects to mineral uptake and skeletal development
were observed in the latter test group (Sayer et al., 1989).
The bioavailability of Pb and other metals that can be simultaneously extracted in
sediments may be modified through the role of acid volatile sulfide (AVS) under anoxic
conditions (Tessier and Campbell, 1987; Di Toro et al., 1992; Casas and Crecelius, 1994). The
term AVS (iron sulfide is an example) refers to the fraction of the sediment that consists of a
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reactive pool of solid-phase sulfide. This phase is available to bind divalent metals that then
become unavailable for uptake by aquatic biota. The models proposed by Di Toro et al. (1992)
and Casas and Crecelius (1994) predict that when the molar ratio of simultaneously extractable
metals (SEM) to AVS in sediments is less than one, the metals will not be bioavailable due to
complexation with available sulfide.
Salinity is an important modifying factor to metal toxicity. Verslycke et al. (2003)
exposed the estuarine mysid Neomysis integer to individual metals, including Pb, and metal
mixtures under changing salinity. At a salinity of 5%, the reported LCso for Pb was 1140 |ig/L
(95% CL = 840, 1440 |ig/L). At an increased salinity of 251, the toxicity of Pb was substantially
reduced (LC50 = 4274 |ig/L [95% CL = 3540, 5710 |ig/L]) (Verslycke et al., 2003). The
reduction in toxicity was attributed to increased complexation of Pb2+ with Cl! ions.
Nutritional Factors
The relationship between nutrition and Pb toxicity has not been thoroughly investigated in
aquatic organisms. In fact, algae species are the only aquatic organisms to have been studied
fairly frequently. Although nutrients have been found to have an impact on Pb toxicity, the
mechanisms involved are poorly understood. It is unclear whether the relationship between
nutrients and toxicity comprises organismal nutrition (the process by which a living organism
assimilates food and uses it for growth and for replacement of tissues), or whether nutrients have
interacted directly with Pb, inhibiting its metabolic interaction in the organism. This section
reviews the little information that has been gathered from studies documenting apparent Pb-
nutrition associations in aquatic organisms.
Jampani (1988) looked at the impact of various nutrients (i.e., sodium acetate, citric acid,
sodium carbonate, nitrogen, and phosphates) on reducing growth inhibition in blue-green algae
(Synechococcus aeruginosus) exposed to 200 mg Pb/L. Exposure to this Pb treatment
concentration caused 100% mortality in algae. Results indicated that additional nitrogen,
phosphates, and some carbon sources, including sodium acetate, citric acid and sodium
carbonate, all protected the algae from Pb toxicity. Algae that had been starved prior to the
experiment were found to be significantly more sensitive to Pb exposure. Glucose was the only
nutrient tested that did not have a significant impact on Pb toxicity in S. aeruginosus. In a
similar study by Rao and Reddy (1985) on Scenedesmus incmssatulus, nitrogen, phosphate and
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carbon sources (including glucose), all had protective effects, and reduced Pb toxicity at 300 and
400 mg Pb/L. Both studies proposed similar hypotheses regarding nutrient-Pb mechanisms that
led to reduced toxicity. One hypothesis was that the nutrients were able to reverse toxic effects.
The second hypothesis was that the nutrients interacted directly with Pb, in some way
sequestering the metal so as to inhibit its metabolic interaction with the organism (Rao and
Reddy, 1985; Jampani, 1988).
Rai and Raizada (1989) investigated the effects of Pb on nitrate and ammonium uptake as
well as carbon dioxide and nitrogen fixation in Nostoc muscorum over a 96-h period. Test
specimens were exposed to 10, 20, and 30 mg Pb/L. At 20 mg Pb/L, nitrate uptake was inhibited
by 64% after 24 h and by 39% after 96 h. Ammonium uptake was inhibited, and similarly,
inhibition decreased from 72% inhibition after 24 h to 26% inhibition after 96 h of exposure.
Carbon dioxide fixation and nitrogenase activity followed similar patterns, and results indicated
that Pb exposure can affect the uptake of some nutrients in N. muscorum.
Adam and Abdel-Basset (1990) studied the effect of Pb on metabolic processes of
Scenedesmus obliquus. They found that nitrogenase activity was inhibited by Pb nitrate, but
enhanced by Pb-acetate. As photosynthetic products and respiratory substrates, carbohydrate
and lipid levels were altered by Pb. Above 30 mg/L of Pb-nitrate, both macronutrients were
reduced. However, Pb-acetate was found to increase carbohydrate levels. Results suggest that
Pb can have an effect on macronutrients in S. obliquus and that effects may vary depending on
the chemical species.
Simoes Gon9alves et al. (1991) studied the impact of light, nutrients, air flux, and Pb, in
various combinations, on growth inhibition in the green algae Selenastrum capricornutum.
Results indicated that at lower Pb concentrations (<0.207 mg/L) and increased nutrient
concentrations, algae release more exudates that form inert complexes with Pb anions in the
water. This suggests that S. capricornutum can use exudates as a protection and that this
protective mechanism depends on nutrient supply. These results are consistent with those of
Capelo et al. (1993), who investigated uptake of nitrogen and phosphorus in the algae
Selenastrum capricornutum over time in the absence and presence of 0.207 mg Pb/L. They
found that the presence of Pb had no significant influence on the assimilation of nitrogen and
phosphorus. However, they did find that in the presence of Pb, algae released higher
concentrations of organics with Pb-chelating groups.
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Amiard et al. (1994) investigated the impact on soft tissue Pb concentrations of various
feeding regimes on oysters (Crassostrea gigas) during their spat rearing. They fed test groups of
C. gigas different amounts of Skeletonema costatum and additional natural phytoplankton grown
in test solutions. Results showed that size and food intake both negatively correlated with metal
concentrations in soft tissue. The authors hypothesized that this relationship was due in part to a
diluting effect of the food.
In summary, nutrients affect Pb toxicity in those aquatic organisms that have been studied.
Some nutrients seem to be capable of reducing toxicity, though the mechanisms have not been
well established. Exposure to Pb has not been shown to reduce nutrient uptake ability, though it
has been demonstrated that Pb exposure may lead to increased production and loss of organic
material (e.g., mucus and other complex organic ligands) (Capelo et al., 1993).
Interactions with Other Pollutants
Most of the scientific literature reviewed in this section considered how Pb and other
elements combine to affect uptake and exert toxicity. Research on the interactions of Pb with
complexing ligands and other physical and biological factors was more thoroughly discussed in
Section AX7.2.3.4. Predicting the response of organisms to mixtures of chemicals is difficult
(Norwood et al., 2003). There are two schools of thought on addressing chemical mixtures in
toxicology. The first focuses on the combined mode of action of the individual mixture
substances while the other focuses on the organism response to the mixture as being additive, or
some deviation from additive (synergistic or antagonistic). The mode of action model assumes
that each of the individual substances has similar pharmacokinetics as well as mode of action.
Approaches to modeling combined mode of action include: 1) joint independent action for
toxicants with different modes of action; and 2) joint similar mode of action. Within the
scientific literature the deviations from additivity approach can be confusing as some authors
report concentration additivity, while others report effect additivity. The concentration additivity
model assumes that the sum of the concentrations will result in a level of effect similar to the
simple sum of the effects observed if each chemical were applied separately (e.g., Herkovits and
Perez-Coll, 1991). Toxic units (TU) may be used to describe the concentration additivity results
for mixtures (e.g., Hagopian-Schlekat et al., 2001). Effects additivity suggests that the level of
effect of a mixture will be the sum of the effects of each chemical used separately. Thus, the
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separate concentration-effects models for each chemical are used to predict individual effects and
the sum of these predictions is then compared to the actual effect of the mixture. Deviations
from the mixture effect are then classified as less than additive (antagonistic) or more than
additive (synergistic) (see Piegorsch et al., 1988; Finney 1947 for further information).
The complexity of metal mixture interactions as different metal concentrations,
environmental conditions (e.g., temperature, pH), and other factors can cause marked changes in
the effects observed (Norwood et al., 2003). In describing Pb interactions with other elements,
the different approaches to modeling mixture toxicity are considered. Specific reference to
known Pb-metal interactions and implications on Pb uptake and toxicity will also be made in
each of the studies below.
Less than additive or antagonistic interactions can reduce metal bioavailability when
metals are present in combination, and may lead to reduced potential for toxicity (Hassler et al.,
2004). A number of elements act in an antagonistic fashion with Pb. For example, Pb is a well-
known antagonist to Ca2+ (Niyogi and Wood, 2004; Hassler et al., 2004), which is an essential
element, required for a number of physiological processes in most organisms. Lead ions have an
atomic structure similar to Ca2+ and can be transported either actively or passively across cell
membranes in place of Ca2+. An example of this interaction was reported by Behra (1993a,b)
where Pb was shown to activate calmodulin reactions in rainbow trout (O. mykiss) and sea
mussel (Mytilus sp.) tissues in the absence of calcium. Calmodulin (CaM) is a major
intracellular calcium receptor and regulates the activities of numerous enzymes and cellular
processes. Allen (1994) reported that Pb can replace calcium in body structures (e.g., bones,
shells); replace zinc in ALAD, which is required for heme biosynthesis; and react with
sulfhydryl groups, causing conformation protein distortion and scission of nucleic acids
(Herkovits and Perez-Coll, 1991). Lead is also a known antagonist to Mg2+, Na+, and Cl!
regulation in fish (Ahern and Morris, 1998; Rogers and Wood, 2003, 2004; Niyogi and Wood,
2004). Li et al. (2004) reported on the interaction of Pb2+ with Cd2+ in the context of adsorption
from solution by Phanerochaete chrysosporium, a filamentous fungus. The authors found that
cadmium uptake decreased with increasing concentration of Pb ions with Pb2+ outcompeting
Cd2+ for binding sites.
Hassler et al. (2004) reported that in the presence of copper (Cu2+), there was a
significantly higher rate of internalization of Pb in the green algae Chlorella kesserii. It was
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suggested that Cu2+ may have affected organism physiology through the disruption of cell
membrane integrity. This would allow increased cation (i.e., Pb2+) permeability and, therefore,
substantially increase internalization of Pb and result in effects that were more than additive
(synergistic). Hagopian-Schlekat et al. (2001) examined the impact of individual metals and
complex metal mixtures containing Cd, Cu, Ni, Zn, and Pb to the estuarine copepod Amphiascus
tenuiremis. The copepods were exposed to metal-spiked sediment and pore water. The mixed
metal sediment toxicity tests demonstrated greater than additive toxicity to A. tenuiremis. It was
postulated that the synergism observed was due to two or more metals affecting the same
biological function. Herkovits and Perez-Coll (1991) exposed Bufo arenarum larvae to various
Pb and zinc concentrations in solution. At low zinc concentrations, (2:1 Pb:Zn ratio),
a synergistic toxic effect was observed in the frog larvae relative to the effects observed from
exposure to the individual metals and at higher zinc concentrations. Enhanced Pb toxicity was
attributed to the interference of Pb with cellular activities due to binding with sulfhydryl
polypeptides and nucleic acid phosphates (Herkovits and Perez-Coll, 1991). Allen (1994)
reported on the accumulation of numerous metals and ions into specific tissues of the tilapia
Oreochromis aureus. Tilapia exposed to low concentrations of Pb and mercury (both at
0.05 mg/L) had significantly higher concentrations of Pb in internal organs than those fish
exposed to Pb alone. Similarly, low concentrations of cadmium with low concentrations of Pb
caused increased uptake of Pb in certain organs (e.g., liver, brain, and caudal muscle).
Lead has been shown to complex with Cl! in aquatic systems. For example, Verslycke
et al. (2003) exposed the estuarine mysid Neomysis integer to six different metals, including Pb,
and a combined metal mixture under changing salinity conditions. At a salinity of 5%, the
reported LC50 for Pb was 1140 |ig/L (840, 1440 |ig/L). At an increased salinity of 251, the
toxicity of Pb was substantially reduced (LC50 = 4274 |ig/L [3540, 5710 Og/L]) (Verslycke
et al., 2003). This reduction in toxicity was attributed to the increased concentration of Cl ion
due to increased salinity, in that it complexed with divalent Pb in the test system. Exposure of TV.
integer to Pb in combination with the other five metals (Hg, Cd, Cu, Zn, Ni) resulted in roughly
strictly additive toxicity (Verslycke et al., 2003).
Long et al. (2006) performed a critical review of the uses of mean sediment quality
guideline quotients (mSQGQs) in assessing the toxic effects of contaminant mixtures (metals and
organics) in sediments. This approach has been used in numerous surveys and studies since
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1994. mSQGQs are useful to risk assessors but their inherent limitations and underlying
assumptions must be fully understood (see Section AX7.2.1.5).
Summary of Interactions With Other Pollutants
Norwood et al. (2003) reported that in a review and reinterpretation of published data on
the interactions of metals in binary mixtures (n = 15 studies), antagonistic (6) and additive
interactions (6) were the most common for Pb. The complexity of the interactions and possible
modifying factors makes determining the impact of even binary metal mixtures to aquatic biota
difficult (Norwood et al., 2003; Playle, 2004). The two most commonly reported Pb-element
interactions are between Pb and calcium and between Pb and zinc. Both calcium and zinc are
essential elements in organisms and the interaction of Pb with these ions can lead to adverse
effects both by increased Pb uptake and by a decrease in Ca and Zn required for normal
metabolic functions.
AX7.2.3.5 Factors Associated with Global Climate Change
It is highly unlikely that Pb has any influence on generation of ground-level ozone,
depletion of stratospheric ozone, global warming, or other indicators of global climate change.
Lead compounds have relatively short residence times in the atmosphere, making it unlikely that
they will reach the stratosphere, and they do not absorb infrared radiation, making them unlikely
to contribute to stratospheric ozone depletion or global warming. Also, these compounds are
unlikely to have a significant interaction with ground-level nitrogen oxides or volatile organic
compounds, thus precluding generation of ground-level ozone.
Approached from another viewpoint, climate change can have a major impact on the
fate/behavior of Pb in the environment and, therefore, can subsequently alter organism or
ecosystem responses. For example, changes in temperature regime (Q10 rule), changes in
precipitation quantity and quality (e.g., acidic deposition) may influence fate, transport, uptake,
and bioavailability of Pb (Syracuse Research Corporation., 1999).
AX7.2.3.6 Summary
There have been a number of advancements in the understanding of Pb behavior in the
environment and its impact on aquatic organisms since 1986. In particular, greater knowledge of
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factors that influence Pb accumulation in aquatic organisms, mechanisms of detoxification and
avoidance of Pb, and greater understanding of the interactions of Pb in aquatic systems. All of
these factors require some consideration when attempting to determine the potential for exposure
and subsequent response of aquatic species to lead. The following section provides a review on
the current understanding of lead and its impacts on aquatic biota.
AX7.2.4 Exposure/Response of Aquatic Species
This section outlines and highlights the critical recent advancements in the understanding
of the toxicity of Pb to aquatic biota. The section begins with a review of the major findings and
conclusions from the 1986 Lead AQCD (U.S. Environmental Protection Agency, 1986a). The
following sections summarize the research conducted since 1986 on determining the
concentrations of Pb that cause the effects discussed in Section 7.2.3.
Lead exposure may adversely affect organisms at different levels of organization, i.e.,
individual organisms, populations, communities, or ecosystems. Generally, however, there is
insufficient information available for single materials in controlled studies to permit evaluation
of specific impacts on higher levels of organization (beyond the individual organism). Potential
effects at the population level or higher are, of necessity, extrapolated from individual level
studies. Available population, community, or ecosystem level studies are typically conducted at
sites that have been contaminated or adversely affected by multiple stressors (several chemicals
alone or combined with physical or biological stressors). Therefore, the best documented links
between lead and effects on the environment are with effects on individual organisms. Impacts
on aquatic ecosystems are discussed in Section 7.2.5 and Annex AX7.2.5.
AX7.2.4.1 Summary of Conclusions From the Previous Criteria Document
The 1986 Lead AQCD (U.S. Environmental Protection Agency, 1986a) reviewed data in
the context of the sublethal effects of lead exposure. The document focused on describing the
types and ranges of lead exposures in ecosystems likely to adversely impact domestic animals.
As such, the criteria document did not provide a comprehensive analysis of the effects of lead to
most aquatic primary producers, consumers, and decomposers. For the aquatic environment,
general reviews of the effects of lead to algae, aquatic vertebrates, and invertebrates were
undertaken. A summary of these reviews is provided below.
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Algae
The 1986 Lead AQCD (U.S. Environmental Protection Agency, 1986a) reported that
some algal species (e.g., Scenedesmus sp.) were found to exhibit physiological changes when
exposed to high lead or organolead concentrations in situ. The observed changes included
increased numbers of vacuoles, deformations in cell organelles, and increased autolytic activity.
Increased vacuolization was assumed to be a tolerance mechanism by which lead was
immobilized within cell vacuoles.
Aquatic Vertebrates
The 1986 Lead AQCD (U.S. Environmental Protection Agency, 1986a) reported that
hematological and neurological responses were the most commonly reported effects in aquatic
vertebrates. These effects include red blood cell destruction and inhibition of the enzyme
ALAD, required for hemoglobin synthesis. At high lead concentrations, neurological responses
included neuromuscular distortion, anorexia, muscle tremor, and spinal curvature (e.g., lordosis).
The lowest reported exposure concentration causing either hematological or neurological effects
was 8 |ig/L (U.S. Environmental Protection Agency, 1986a).
Aquatic Invertebrates
Numerous studies were cited on the effects of lead to aquatic invertebrates in the 1986
Lead AQCD (U.S. Environmental Protection Agency, 1986a). In general, lead concentrations in
aquatic invertebrates were found to be correlated closely with concentrations in water rather than
food. Freshwater snails were found to accumulate lead in soft tissue, often in granular bodies of
precipitated lead. Mortality and reproductive effects were reported to begin at 19 jig Pb/L for the
freshwater snail Lymneapalutris and 27 jig Pb/L for Daphnia sp.
The review of the NAAQS for Pb (U.S. Environmental Protection Agency, 1990) made
only one recommendation reported in the sections of the 1986 Lead AQCD dealing with effects
to aquatic biota. This was the need to consider the impact of water hardness on Pb
bioavailability and toxicity, to be consistent with the recommendations of the AWQC for the
protection of aquatic life (U.S. Environmental Protection Agency, 1985).
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AX7.2.4.2 Recent Studies on Effects of Lead on Primary Producers
Using literature published since the 1986 Lead AQCD (U.S. Environmental Protection
Agency, 1986a), this section examines the toxicity of Pb (individually and in metal mixtures) to
algal and aquatic plant growth, its effects on metabolic processes (e.g., nutrient uptake), and its
impact on primary productivity in natural systems.
Toxicity of Lead to Algae
The toxicity of Pb to algal growth has been investigated for a number of species including
Chlorella vulgaris, Closterium acerosum, Pediastrum simplex, Scenedesmus quadricauda,
Scenedesmu obliquus, Syneschoccus aeruginosus, and Nostoc muscorum (Jampani, 1988; Rai
and Raizada, 1989; Adam and Abdel-Basset, 1990; Fargasova, 1993; Bilgrami and Kumar,
1997). Study durations ranged from 7 to 20 days and Pb-nitrate was the most commonly used
form of Pb. Effects to algal growth (Chlorella vulgaris, Closterium acerosum, Pediastrum
simplex, Scenedesmus quadricauda), ranging from minimal to complete inhibition, have been
reported at Pb concentrations between 100 and 200,000 |ig/L (Jampani, 1988; Bilgrami and
Kumar, 1997). Most studies report the percent inhibition in test groups compared to controls
rather than calculating the LOEC, NOEC, or ECso values. Clinical signs of Pb toxicity include
the deformation and disintegration of algae cells and a shortened exponential growth phase
(Jampani, 1988; Fargasova, 1993). Other effects of Pb block the pathways that lead to pigment
synthesis, thus affecting photosynthesis, the cell cycle and division, and ultimately result in cell
death (Jampani, 1988).
From the studies reviewed, Closterium acerosum is the most sensitive alga species tested
(Bilgrami and Kumar, 1997). Exposure of these algae to 1000 and 10,000 jig/L as lead nitrate
for 6 days resulted in cell growth that was 52.6 and 17.4%, respectively, of controls (Bilgrami
and Kumar, 1997). Chlorella vulgaris, Pediastrum simplex, and Scenedesmus quadricauda were
also exposed to Pb-nitrate in this study. Compared to controls, cell growth at 1000 and
10,000 |ig Pb-nitrate/L was 65.3 and 48.7%, 64.5 and 42.7%, and 77.6 and 63.2%, respectively
(Bilgrami and Kumar, 1997). Scenedesmus quadricauda exhibited a similar magnitude of effects
when exposed to lead (Pb2+) for 20 days at 0, 5500, 11,000, 16,500, 22,000, 27,500, and
33,000 |ig/L (Fargasova, 1993). This study reported an ECso for growth inhibition at
13,180 |ig/L (95% CI: 10,190, 14,620). Decreased cell number, but increased cell size, was
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observed in Selenastrum capricornutum1 exposed to lead (Pb2+) at 207.2 |ig/L and a Q/V (flux of
air [Q] divided by volume of the culture [V]) of 4.7 H 10!3 sec'1 for 9 days (Simoes Gon9alves
et al., 1991). The Q/V is a measure of culture growth where an increase in the Q/V ratio
indicates growth. The pigment concentration per cell decreased with exposure to Pb, so while
the algae cells were larger, they were less healthy (Simoes Gon9alves et al., 1991). Growth rates
were not reported, making comparison with other studies difficult.
High Pb concentrations were required to elicit effects in Nostoc muscorum and
Scenedesmus aeruginosus (Jampani, 1988; Rai andRaizada, 1989). Following 15-day
exposures, test groups exposed to 10,000, 20,000, and 30,000 jig Pb/L experienced growth rates
that were 90.5, 76.9, and 66.7% of the controls (Rai and Raizada, 1989). Synechococcus
aeruginosus experienced little inhibition of growth from exposure to Pb-nitrate up to a
concentration of 82,000 |ig/L (Jampani, 1988). At a test concentration of 100,000 |ig/L,
complete inhibition of growth was observed, and at a concentration of 200,000 |ig/L, algae failed
to establish a single colony (Jampani, 1988). Scenedesmus obliquus are quite tolerant to the
effects of Pb-nitrate and Pb-acetate on growth. Algae exposed to Pb-nitrate or Pb-acetate up to
180,000 |ig/L had higher cell numbers than controls (Adam and Abdel-Basset, 1990). Exposure
to the highest concentration of 300,000 |ig/L Pb-nitrate or Pb-acetate resulted in cell numbers
that were 81 and 90% of the controls, respectively (Adam and Abdel-Basset, 1990).
Lead in combination with other metals (e.g., Pb and Cd, Pb and Ni, etc.) is generally less
toxic than exposure to Pb alone (Rai and Raizada, 1989). Nostoc muscorum exposed to
chromium and Pb in combination demonstrated better growth than when exposed to either of the
metals alone (Rai and Raizada, 1989). Antagonistic interaction was observed in the exposure of
Nostoc muscorum to Pb and nickel in combination (Rai and Raizada, 1989). When applied
separately, these metals demonstrated different levels of toxicity; however, in combination, they
exerted similar effects (Rai and Raizada, 1989). More information on toxic interactions of Pb
with other metals is provided in Section AX7.2.3.5.
The species name Selenastrum capricornutum has been changed to Pseudokirchneriella subcapitata. The
former species name is used in this report.
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Aquatic Plants
The toxicity of Pb to aquatic plant growth has been studied using Spirodelapolyrhiza,
Azollapinnata, and Lemna gibba (Gaur et al., 1994; Gupta and Chandra, 1994; Miranda and
Ilangovan, 1996). Test durations ranged from 4 to 25 days and test concentrations ranged
between 49.7 and 500,000 |ig Pb/L (Gaur et al., 1994; Miranda and Ilangovan, 1996). Research
on aquatic plants has focused on the effects of Pb on aquatic plant growth and chlorophyll and
protein content.
Of the species reviewed here, the effects of Pb on aquatic plant growth are most
pronounced in Azollapinnata (Gaur et al., 1994). An ECso of 1100 |ig/L was reported for
A. pinnata exposed to Pb-nitrate for 4 days. S. polyrhiza exposed to Pb-nitrate under the same
test conditions had a reported ECso for growth of 3730 |ig/L (Gaur et al., 1994). Lemna gibba
was shown to be the least sensitive plant species to Pb: significant growth inhibition was
reported at concentrations of 200,000 |ig/L or greater after 25 days of exposure to concentrations
of 30,000, 50,000, 100,000, 200,000, 300,000, or 500,000 |ig/L (Miranda and Ilangovan, 1996).
The maximum growth rate for L. gibba was observed at 10 days of exposure. After this point,
the growth rate declined in controls and test concentrations (Miranda and Ilangovan, 1996).
Clinical signs of Pb toxicity include yellowing and disintegration of fronds, reduced frond size,
and chlorosis (Gaur et al., 1994; Miranda and Ilangovan, 1996). Toxicity results suggest that
effects to growth from Pb exposure occur in a dose-dependent manner (Gaur et al., 1994).
Effects of Lead on Metabolic Processes
Algal and aquatic plant metabolic processes are variously affected by exposure to Pb, both
singularly and in combination with other metals. Lead adversely affects the metabolic processes
of nitrate uptake, nitrogen fixation, ammonium uptake, and carbon fixation at concentrations of
20,000 jig Pb/L or greater (Rai and Raizada, 1989). Lead in combination with nickel has an
antagonistic effect on nitrogen fixation and ammonium uptake, but a synergistic effect on nitrate
uptake and carbon fixation (Rai and Raizada, 1989). Lead in combination with chromium has an
antagonistic effect on nitrate uptake, but it has a synergistic effect on nitrogen fixation,
ammonium uptake, and carbon fixation (Rai and Raizada, 1989).
Lead effects on nitrate uptake in Nostoc muscorum (jig NCVjig Chi a) were greatest after
24 h, when exposure to 20,000 |ig/L reduced nitrate uptake by 64.3% compared to controls.
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Nitrate uptake reported after 48, 72, and 96 h was reduced by 30.0, 37.5, and 38.9%,
respectively, compared to controls (Rai and Raizada, 1989). Lead in combination with
chromium, both at a test concentration of 20,000 |ig/L, demonstrated antagonistic effects on
nitrate uptake. Compared to controls, nitrate uptake was reduced by 52.4, 30, 25, and 22.2% at
24, 48, 72 and 96 h, respectively (Rai and Raizada, 1989). The greatest effect on uptake
occurred at 24 h when, compared to controls, a 52.4% reduction was reported in the test
concentration. Lead and nickel in combination at test concentrations of 20,000 and 1000 |ig/L,
respectively, resulted in a greater reduction of nitrate uptake than Pb alone at 48, 72, and 96 h
(Rai and Raizada, 1989).
After 24, 48, and 72 h of Pb exposure at 20,000 |ig/L, nitrogenase activity (nmol C2H4/ jig
protein/hr) in Nostoc muscorum was reduced by 39.3, 61.8, and 14.1%, respectively, compared
to controls (Rai and Raizada, 1989). A concentration of 207.2 jig Pb/L had little effect on
nitrogen or phosphorus assimilation in Selenastrum capricornutum over 7 days (Capelo et al.,
1993). An antagonistic effect on nitrogenase activity was generally reported for Nostoc
muscorum exposed to Pb in combination with nickel at 20,000 and 1,000 |ig/L, respectively
(Rai and Raizada, 1989). Compared to controls, nitrogenase activity was reduced by 42.9, 32.7,
and 13.6% at 24, 48, and 72 h, respectively (Rai and Raizada, 1989). Lead and chromium, both
administered at a concentration of 20,000 |ig/L, had a synergistic impact on nitrogenase activity
in Nostoc muscorum. Nitrogenase activity in the test group was reduced by 60.7, 60, and 50%
compared to the controls at 24, 48, and 72 h, respectively (Rai and Raizada, 1989).
Lead-induced inhibition of ammonium uptake (jig NIL; uptake/jig Chi a) was greatest in
Nostoc muscorum after 48 h of exposure to 20,000 |ig/L of lead. Compared to controls, the Pb
test concentration 20,000 |ig/L reduced ammonium uptake by 72, 82, 61, and 26 % at 24, 48, 72,
and 96 h, respectively (Rai and Raizada, 1989). Lead in combination with nickel at
concentrations of 20,000 and 1,000 |ig/L, respectively, demonstrated an antagonistic effect on
ammonium uptake. Compared to controls, ammonium uptake in the test group was reduced by
44.9, 54.1, 23.3, and 4% at 24, 48, 72, and 96 h, respectively (Rai and Raizada, 1989). Lead in
combination with chromium, both at concentrations of 20,000 |ig/L, demonstrated a synergistic
interaction with 24, 48, 72, and 96 h uptake rates reduced by 87.2, 88.5, 72.5, and 50 %,
respectively, compared to controls (Rai and Raizada, 1989).
AX7-180
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Nostoc muscorum exposed to 20,000 jig Pb/L experienced the greatest reduction in carbon
fixation at 0.5 h of exposure: 62% compared to controls. Inhibition of carbon fixation in the test
group was less pronounced after 1 and 2 h of exposure: 29 and 13% of controls (Rai and
Raizada, 1989). Lead in combination with nickel or chromium had synergistic effects to carbon
fixation. Lead and nickel concentrations of 20,000 and 1000 |ig/L, respectively, resulted in 0.5,
1, and 2 h carbon fixation rates reduced by 93, 92, and 91%, respectively, compared to controls
(Rai and Raizada, 1989). Lead with chromium at concentrations of 20,000 |ig/L resulted in 0.5,
1, and 2 h carbon fixation rates reduced by 65, 58, and 50%, respectively, compared to controls.
Nutrients such as nitrogen, phosphate, sodium acetate, sodium carbonate, and citric acid
have been shown to protect against the toxic effects of Pb to algae (Jampani, 1988). Nitrogen
compounds (ammonium chloride, potassium nitrate, sodium nitrate, sodium nitrite) protected
Synechococcus aeruginosus from a lethal Pb-nitrate dose of 200,000 |ig/L (Jampani, 1988). Two
phosphates (K2HPO4 and Na2HPC>4) were found to improve Synechococcus aeruginosus survival
from 0 to 72% at 200,000 |ig/L of Pb-nitrate (Jampani, 1988).
Compared to controls, protein content was reduced by 54.2 and 51.9% in aquatic plants
Vallisneria spiralis and Hydrilla verticillata, respectively, exposed to Pb for 7 days at
20,720 |ig/L (Gupta and Chandra, 1994). Decreased soluble protein content has been observed
in Scenedesmus obliquus exposed to Pb-nitrate or Pb-acetate at concentrations greater than
30,000 |ig/L, and in L. gibba at concentrations greater than 200,000 |ig/L (Adam and
Abdel-Basset, 1990; Miranda and Ilangovan, 1996). Lemna gibba also showed increased loss of
soluble starch at concentrations >200,000 |ig/L (Miranda and Ilangovan, 1996). Under the
conditions described previously (Gupta and Chandra, 1994), ECso values for chlorophyll content
were 14,504 and 18,648 |ig/L for Vallisneria spiralis and Hydrilla verticillata, respectively
(Gupta and Chandra, 1994). Effects to chlorophyll a content have been observed in
Scenedesmus obliquus at Pb-nitrate and Pb-acetate concentrations >30,000 |ig/L (Adam and
Abdel-Basset, 1990).
Summary of Toxic Effects Observed in Single-Species Bioassays
Algae and aquatic plants have a wide range in sensitivity to the effects of Pb in water.
Both groups of primary producers experience ECso values for growth inhibition between
approximately 1000 and >100,000 |ig/L (Jampani, 1988; Gaur et al., 1994; Bilgrami and Kumar,
AX7-181
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1997). The most sensitive primary producers reported in the literature for effects to growth were
Closterium acersoum and Azollapinnata (Gaur et al., 1994; Bilgrami and Kumar, 1997). The
least sensitive primary producers reported in the literature for effects to growth were
Synechococcus aeruginosus and Lemna gibba (Jampani, 1988; Miranda and Ilangovan, 1996).
Exposure to Pb in combination with other metals is generally less toxic to growth than exposure
to lead alone. Studies have shown that lead adversely affects the metabolic processes of nitrate
uptake, nitrogen fixation, ammonium uptake, and carbon fixation (Rai and Raizada, 1989). Lead
in combination with nickel or chromium produced synergistic effects for nitrate uptake,
nitrogenase activities, ammonium uptake, and carbon fixation (Rai and Raizada, 1989).
Leads Effects on Primary Productivity
Lead nitrate and Pb-acetate have been shown to have adverse effects on the primary
productivity of aquatic plants in two water bodies in India (Jayaraj et al., 1992). One of the two
water bodies was a freshwater tank that receives wastewater and supports a rich population of
hyacinths, and the other was a wastewater stabilization pond. Water quality characteristics in the
freshwater tank were pH = 7.5, dissolved oxygen = 6 mg/L, and water hardness (CaCOs) =
100 mg/L. Water quality characteristics in the wastewater pond were pH = 8.1, dissolved
oxygen = 6.2 mg/L, and water hardness (CaCOs) = 160 mg/L (Jayaraj et al., 1992). Lead nitrate
concentrations of 500, 5000, 10,000, 25,000, and 50,000 |ig/L were combined with appropriate
water samples in light and dark bottles and suspended in each of the water bodies for 4 h. The
concentrations of Pb-acetate (5000, 10,000, 25,000, 50,000, and 100,000 |ig/L) were applied in
the same manner. The ECso values were determined based on the concentration required to
inhibit gross productivity (GP) and net productivity (NP) by 50% (Jayaraj et al., 1992). The
results demonstrated that Pb-nitrate was more toxic to primary production than Pb-acetate.
In the freshwater tank, Pb-nitrate EC50 values for GP and NP were 25,100 and 6310 |ig/L,
respectively, compared to Pb-acetate ECso values of 50,100 and 28,200 |ig/L for GP and NP,
respectively (Jayaraj et al., 1992). In the stabilization pond, Pb-nitrate ECso values for GP and
NP were 31,600 and 28,200 |ig/L, respectively, compared to Pb-acetate ECso values of 79,400
and 316 |ig/L for GP and NP, respectively (Jayaraj et al., 1992). The higher toxicity reported in
the freshwater tank was attributed to differences in species composition and diversity. The
freshwater tank was dominated by water hyacinths that decreased the photic zone available for
AX7-182
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photosynthesis and consumed a great deal of available nutrients. The stabilization pond had
a rich nutrient budget, resulting in improved alga growth and species diversity (Jayaraj
etal., 1992).
AX7.2.4.3 Recent Studies on Effects of Lead on Consumers
This section focuses on the effects of Pb to aquatic biota including invertebrates, fish, and
other biota with an aquatic life stage (e.g., amphibians). It is not intended to be a comprehensive
review of all research conducted. Rather, the intent is to illustrate the concentrations and effects
of Pb on freshwater and marine aquatic species. Eisler (2000) provides an overview of much of
the recent available literature on the toxicity of Pb to fish and aquatic invertebrates. An
extensive literature search was conducted using numerous electronic bibliographic and database
services (e.g., DIALOG, EPA ECOTOX) and limited temporally from 1986 to present. This
temporal limit was due to the availability of the EPA water quality criteria report for the
protection of aquatic life, released in 1986 (U.S. Environmental Protection Agency, 1986b).
Based on the results of the literature search and recent reviews of the toxicity of Pb (Eisler,
2000), numerous studies have been published on the toxicity of Pb to aquatic consumers.
Hardness, pH, temperature, and other factors are important considerations when characterizing
the acute and chronic toxicity of lead (Besser et al., 2005) (Section AX7.2.3.5). However, many
of the studies reviewed did not report critical information on control mortality, water quality
parameters, or statistical methods, making comparing effects between studies difficult. Studies
reporting only physiological responses to Pb exposure (e.g., reduction of ALAD) are not
discussed here, as this topic was covered more completely in Section AX7.2.3.4. This section
provides a review of toxicity studies conducted with invertebrates, fish, and other aquatic
organisms.
Invertebrates
Exposure of invertebrates to Pb can lead to adverse effects on reproduction, growth,
survival, and metabolism (Eisler, 2000). The following presents information on the toxicity of
Pb to invertebrates in fresh and marine waters.
AX7-183
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Freshwater Invertebrates
Acute and chronic Pb toxicity data for freshwater invertebrates are summarized in Table
AX7-2.4.1. As described in Section AX7.2.3.5, water hardness is a critical factor governing the
solubility, bioavailability, and ultimately the toxicity of Pb. The acute and chronic toxicity of Pb
increases with decreasing water hardness as Pb becomes more soluble and bioavailable to
aquatic organisms. For example, Borgmann et al. (2005) examined the toxicity of 63 metals,
including Pb, to Hyalella azteca at two levels of water hardness (soft water hardness, 18 mg
CaCOs/L; hard water, 124 mg CaCOs/L). Lead was 23 times more acutely toxic to H. azteca in
soft water than hard water. Besser et al. (2005) found that acute toxicity to H. azteca was also
modified by water hardness.
At a mean pH of 7.97 in soft water (hardness (CaCOs) = 71 mg/L) mortality was >50%
for//, azteca at a dissolved Pb concentration of 151 |ig/L. The LOEC for survival in hard water
(hardness (CaCO3) = 275 mg/L) at pH 8.27 was 192 |ig/L as dissolved Pb and 466 |ig/L as total
Pb. Both waterborne and dietary Pb were found to contribute to reduced survival of//, azteca
(Besser et al., 2005).
Exposure duration may also play an important role in Pb toxicity in some species.
For example, Kraak et al. (1994) reported that filtration in the freshwater mussel Dreissena
polymorpha was adversely affected at significantly lower Pb concentrations over 10 weeks of
exposure than was the case after 48 h of exposure.
The influence of pH on lead toxicity in freshwater invertebrates varies between
invertebrate species. Over a 96-h exposure period, mortality increased with decreasing pH in the
bivalve Pisidium casertanum, while pH-independent mortality was reported for gastropod and
crustacean species under similar exposure conditions (Mackie, 1989). Cladocerans
(Ceriodaphnia dubia), amphipods (//. azteca), and mayflies (Leptophlebia marginata) were also
more sensitive to Pb toxicity at lower pH levels (Schubauer-Berigan et al., 1993; Gerhardt,
1994). Lead was 100 times more toxic to the amphipod, Hyalella azteca, at a pH range of 5.0 to
6.0 (Mackie, 1989) than at a pH range of 7.0 to 8.5 (Schubauer-Berigan et al., 1993).
The physiology of an aquatic organism at certain life stages may be important when
determining the toxicity of metals to test organisms. For example, Bodar et al. (1989) exposed
early life stages ofDaphnia magna to concentrations of Pb(NC>3)2. The test medium had a pH
of 8.3 V 0.2, water hardness (CaCOs) of 150 mg/L, and temperature of 20 V 1 EC. Lead
AX7-184
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Table AX7-2.4.1. Effects of Lead to Freshwater and Marine Invertebrates
Species
Freshwater
Cladoceran
(Ceriodaphnia dubia)
Worm
(Lumbriculus variegatus)
X
^ Amphipod
^ (Hyalella azteca)
Amphipod
(Hyalella azteca)
Amphipod
(Hyalella azteca)
Mayfly
(Leptophlebia marginata)
Mayfly
(Leptophlebia marginata)
Chemical
lead
chloride
lead
chloride
lead
chloride
lead
chloride
lead
chloride
lead
chloride
lead
chloride
Endpoint:
Cone. Oig/L)*
LC50:
280
>2,700
>2,700
LC50:
>8,000
>8,000
>8,000
LC50:
<90
>5,400
>5,400
LC50:
27(20.1-36.4)
LC50:
60 (53.6-67.3)
LC50:
1090
(400-133200)
LC50:
5000
Duration of
Exposure Water Chemistry
48 h pH:
6-6.5
7-7.5
8-8.5
Hardness: 280-300 mg/L CaCO3
96 h pH:
6-6.5
7-7.5
8-8.5
Hardness: 280-300 mg/L CaCO3
96 h pH:
6-6.5
7-7.5
8-8.5
Hardness: 280-300 mg/L CaCO3
8 days Hardness
130 mg/L
pH 7.8-8.6
8 days Hardness
130 mg/L
pH 7.8-8.6
96 h pH:
4.5
96 h pH
7.0
Test Type - Effect
static-survival
static-survival
static-survival
renewal, 1 -week-
old amphipods
renewal, 10- to 16-
week old
amphipods
acute - survival
acute - survival
Reference
Schubauer-Berigan
etal. (1993)
Schubauer-Berigan
etal. (1993)
Schubauer-Berigan
etal. (1993)
MacLean et al.
(1996)
MacLean et al.
(1996)
Gerhardt (1994)
Gerhardt (1994)
-------
Table AX7-2.4.1 (cont'd). Effects of Lead to Freshwater and Marine Invertebrates
X
-------
Table AX7-2.4.1 (cont'd). Effects of Lead to Freshwater and Marine Invertebrates
Species
Mayfly
(Leptophlebia marginata)
Cladoceran
(D. magna)
Cladoceran
(D. magna)
Cladoceran
(D. magna)
X Amphipod
^ (Hyalella azteca)
oo
Tubificid worm
(Tubifex tubifex)
Marine
Copepod
(Amphiascus tenuiremis)
Bivalve
(Mytilus galloprovincialis)
Chemical
lead
chloride
lead
nitrate
lead
chloride
lead
chloride
lead
lead
nitrate
lead
lead
nitrate
Endpoint:
Cone. (*g/L)*
LC50:
1090 (95% C.I. =
133.2)
>5000
LC50:
0.45
NOEC:
260
NOEC:
270
LOEC:
(Dissolved Pb)
192
(Total Pb) 466
EC50:
237(183-316)
142 (107-184)
LC50: sediment
2462 ug
metal/dry
sediment
EC50 : 221
(58.9-346.3)
LOEC : 50
Duration of
Exposure
96 h
48 h
12 to 21 d
10 d
96 h
24 h
48 h
96 h
Water Chemistry
pH = 4.5-6.5;
DOC-21.6mgCl!1;
Cond = 7.0 OS cm!1
pH = 8.3V 0.2
Hardness (CaCO3) = 150 mg/L
Temp= 20 EC
Not specified
Not specified
pH = 8.27
Hardness (CaCO3) = 275 mg/L
Temp = 21.1EC
pH = 7.5-7.7
Hardness = 245 mg/L
Temp = 29.5-3 1 EC
pH = 7.7V 0.1
Dissolved O2 -6.3 V 0.3 mg/L
Salinity - 32 ppt
artificial seawater
Test Type - Effect
renewal - survival
static -
embryogenesis
renewal -
reproduction
renewal - growth
flow through -
survival
static -
immobilization
embryogenesis
Reference
Gerhardt (1994)
Bodaretal. (1989)
Enserink et al.
(1991)
Enserink et al.
(1991)
Besser et al. (2005)
Khangarot(1991)
Hagopian-Schlekat
etal. (2001)
Beiras and
Albentosa (2003)
* - Brackets after effect concentration are 95% confidence intervals.
-------
concentrations of < 100 mg/L had no impact on Daphnia egg development. The authors
suggested that this might due to the Daphnia egg structure, which consists of two layers: the
inner vitelline layer and outer chlorion layer. The chlorion layer in other species (e.g., rainbow
trout) is known to adsorb metals, thereby, preventing ionic injury to the developing embryo.
Exposures to sediment-associated Pb can be toxic to sediment-dwelling organisms.
In freshwater sediments, 48-h exposure of water fleas (Daphnia magnd) to 7000 mg Pb/kg dw
significantly reduced mobility, while exposure to 13,400 mg Pb/kg dw for 24 h produced the
same effect (Dave, 1992a,b). Longer-term (i.e., 14-day) exposure of midges (Chironomus
tentans) to sediments containing 31,900 mg Pb/kg dw resulted in 100% mortality.
Marine Invertebrates
In estuarine environments, salinity is an important modifying factor to Pb toxicity.
Verslycke et al. (2003) exposed the estuarine mysid Neomysis integer to individual metals,
including Pb, and metal mixtures under changing salinity. Water temperature (20 V 1°C) and
salinity were reported, although no other water quality parameters were available (e.g., pH, water
hardness). At a salinity of 51, the reported LC50 for Pb was 1140 |ig/L (95% CI: 840,
1440 |ig/L). At an increased salinity of 251, the toxicity of lead was substantially reduced (LCso
= 4274 |ig/L [3540, 5710 |ig/L]) (Verslycke et al., 2003).
Sensitivity to Pb can also vary between genders in some aquatic organisms. For example,
Hagopian-Schlekat et al. (2001) examined the toxicity of Pb-chloride in sediment and sediment
pore water to female and male estuarine copepods Amphiascus tenuiremis. The reported LCso
for total lead was 2462 mg Pb/kg dw (95% CI: 2097, 2891 mg Pb/kg dw). Gender effects were
observed in that male copepods were more sensitive (p = 0.038) to Pb than females as
determined by generalized linear model analysis.
Beiras and Albentosa (2003) examined the inhibition of embryo development in
commercial bivalves Ruditapes decussatus andMytilus galloprovincialis after exposure to
concentrations of Pb(NO3)2 in seawater. No water chemistry parameters other than temperature
were reported (test conducted at 20 °C). An ECso range for R. decussatus was reported as 156 to
312 |ig/L, as insufficient data were available to calculate the actual ECso. The lowest observable
effect concentration (LOEC) was 156 |ig/L. ForM galloprovincialis, the ECso was 221 |ig/L
(95% CI: 58.9, 346.3) while the LOEC was reported as 50 |ig/L.
AX7-188
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Fish
The general symptoms of Pb toxicity in fish include production of excess mucus, lordosis,
anemia, darkening of the dorsal tail region, degeneration of the caudal fin, destruction of spinal
neurons, ALAD inhibition, growth inhibition, renal pathology, reproductive effects, growth
inhibition, and mortality (Eisler, 2000). Toxicity in fish has been closely correlated with
duration of Pb exposure and uptake (Eisler, 2000). The following presents information on the
toxicity of Pb to fish in fresh and marine waters. Table AX7-2.4.2 summarizes the effects of Pb
on freshwater and marine fish.
Freshwater Fish
Many of the toxicity modifying factors described above and in Section AX7.2.3.5 (e.g.,
pH, DOC) for invertebrates are also important modifying factors for Pb toxicity to fish species.
The effects of pH on Pb bioavailability and subsequent toxicity have been well-studied (Sayer
etal., 1989; Spry and Wiener, 1991; Schubauer-Berigan et al., 1993; Stouthart et al., 1994;
MacDonald et al., 2002; Rogers and Wood, 2003). Schubauer-Berigan et al. (1993) exposed
fathead minnow to Pb-chloride over 96 hours. The reported LCso ranged from 810 to
>5400 |ig/L at pH 6 to 6.5 and pH 7 to 8.5, respectively.
Water hardness also has a strong influence on the effects of lead to fish. Chronic
exposure of rainbow trout fry to Pb in soft water resulted in spinal deformities at 71 to 146 |ig/L
after 2 months of exposure (Sauter et al., 1976) or 13.2 to 27 |ig/L (Davies and Everhart, 1973;
Davies et al., 1976), after 19 months of exposure. When exposed to Pb in hard water, only 0 and
10% of the trout (Oncorhynchus mykiss) developed spinal deformities at measured Pb
concentrations of 190 and 380 |ig/L, respectively. In soft water, 44 and 97% of the trout
developed spinal deformities at concentrations of 31 and 62 |ig/L, respectively (Davies et al.,
1976). The maximum acceptable toxicant concentration (MATC) for rainbow trout fry in soft
water was 4.1 to 7.6 |ig/L (Davies et al., 1976), while the MATC for brook trout was 58 to
119 |ig/L (Holcombe et al., 1976). Histological reproductive abnormalities were noted in mature
male rainbow trout at 10 |ig/L Pb-nitrate (Ruby et al., 1993).
Schwartz et al. (2004) examined the influence of NOM on Pb toxicity to rainbow trout
exposed for 96 h in a static system. The pH of the exposure system ranged between 6.5 and 7.0,
temperature was maintained between 9 and 11 EC, and Pb was added as PbCb. NOM from a
AX7-189
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Table AX7-2.4.2. Effects of Pb to Freshwater and Marine Fish
X
VO
o
Species
Freshwater
Fathead minnow
(Pimephales promelas)
Rainbow trout - mature
males
(Oncorhynchus mykiss)
Fathead minnow
(Pimephales promelas)
Rainbow trout - Juvenile
(Oncorhynchus mykiss)
Chemical
lead
chloride
lead
nitrate
lead
acetate
lead
nitrate
Endpoint:
Cone. (Og/L)
LC50:
810
>5,400
>5,400
Reproductive effects:
10
Reproductive Effects:
500
LC50: 1000
(800 - 1400)
Duration of
Exposure Water Chemistry
96 h pH:
6-6.5
7-7.5
8-8.5
Hardness: 280-300
mg/L CaCO3
12 days Hardness 128 mg/L
CaC03
29 days pH:
7.5-8.5;
Hardness 130 mg/L
CaCO3;
22-25 EC
(Pb 95% soluble)
96 h pH:
7.9-8.0
Comments
static, measured
Decreased
spermatocyte
development
Fewer viable eggs
produced, testicular
damage
Flow through - Survival
Reference
Schubauer-Berigan
etal. (1993)
Ruby etal. (1993)
Weber (1993)
Rogers and Wood
(2003)
Common carp
(Cyprinus carpio)
not LC50:
reported 6.5 cm fish- 1030
3.5 cm fish-300
DOC = 3 mg/L
Hardness (CaCO3) =
140 mg/L
96 h pH:
7.1
Temperature-15 EC
Oxygen sat. 6.4 mg/L
static-renewal -
Survival
Alam and Maughan
(1995)
-------
number of U.S. rivers and lakes was then added to the test system, and the LT50 was reported.
NOM was found to reduce the toxic effects of Pb to rainbow trout.
Fish size is an important variable in determining the adverse effects of Pb. Alam and
Maughan (1995) exposed two different sizes of common carp (Cyprinus carpio) to Pb
concentrations to observed effects on carp mortality. Water chemistry parameters were reported
(pH = 7.1', temperature = 20 EC). Smaller fish (3.5 cm) were found to be more sensitive to Pb
than were larger fish (6.5 cm). The reported LCsoS were 0.44 mg/L and 1.03 mg/L, respectively.
Marine Fish
There were no studies available that examined the toxicity of Pb to marine fish species for
the time period examined (1986 to present). However, Eisler (2000) reviewed available research
on Pb toxicity to marine species and reported studies done prior to 1986. Acute toxicity values
ranged from 50 |ig/L to 300,000 |ig/L in plaice (Pleuronectesplatessd) exposed to organic and
inorganic forms of Pb (Eisler, 2000). Organolead compounds (e.g., tetramethyl Pb, tetraethyl Pb,
triethyl Pb, diethyl Pb) were generally more toxic to plaice than inorganic Pb (Maddock and
Taylor, 1980).
Other Aquatic Biota
A paucity of data exist on the effects of Pb to growth, reproduction, and survival of
aquatic stages of frogs and turtles. Rice et al. (1999) exposed frog larvae (Rana catesbeiand) to
780 jig Pb/L and two oxygen concentrations (3.5 or 7.85 mg/L) for 7 days (Table AX7-2.4.3).
Exposure conditions included water hardness of 233 to 244 mg CaCOs/L, pH from 7.85 to 7.9,
and temperature at 23 EC. Frog larvae were found to display little to no activity in the low
oxygen and high Pb treatment. Hypoxia-like behavior was exhibited in larvae exposed to both
low and high oxygen concentrations and high Pb. Therefore, larvae of R. catesbeiana showed
sensitivity to Pb and responded with hypoxia-like behavior. Additionally, the larvae in the Pb
treatment were found to have lost body mass relative to controls and the other treatments. Rice
et al. (1999) suggested that the decrease in mass likely indicated the beginning of a period of
reduced growth rate. Larvae exposed for longer periods (>4 weeks) were smaller and
metamorphosed later compared to unexposed individuals.
AX7-191
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Table AX7-2.4.3. Nonlethal Effects in Amphibians
X
to
Species
Frogs
(Rana ridibunda)
Frogs
(Bufo arenamm)
Frogs
Endpoint:
Chemical Concentration
lead nitrate Biochemical effects:
14,000 ug/L
Mortality:
16 mg Pb2+/L
Hypoxia-like behavior:
Duration of
Exposure
30 days
5 days
7 days
Water Chemistry
Not specified
Not specified
O2 = 3. 5-7.85 mg/L
Comments
Hepatic ALAD decreased by
90%
Effects reported include erratic
swimming, loss of equilibrium
Larvae used
Reference
Vogiatzis and
Loumbourdis (1999)
Herkovits and Perez-Coll
(1991)
Puce etal. (1999)
(Rana catesbeiana)
780 ug/L
Turtle Hatchlings lead acetate NOEL: 100 ug/g
(Trachemys scripta) (Survival and
behavior)
4 weeks
pH = 7.85-7.9
Temp = 23 EC
CaCO3 = 233-244
mg/L
N/A
Exposure via single injection Burger et al. (1998)
-------
Herkovits and Perez-Coll (1991) examined Pb toxicity to amphibian larvae (Bufo
arenarum). Larvae (n = 50) were exposed for up to 120 h at two Pb concentrations, 8 mg Pb2+/L
and 16 mg Pb2+/L. Relative to controls, the 8 mg Pb2+/L treatment group exhibited 40%
mortality and the 16 mg Pb2+/L group 60% mortality after 120 h (p < 0.05). The authors reported
behavioral effects, erratic swimming, and loss of equilibrium during the tests, symptoms that are
consistent with the action of Pb on the central and peripheral nervous systems (Rice et al., 1999).
Behavior (i.e., righting, body turnover, seeking cover), growth, and survival of hatchling
slider turtles (Trachemys scriptd) exposed to Pb-acetate were investigated in one study (Burger
et al., 1998). In the first part of the study, 6-month-old hatchlings received single Pb-acetate
injections at 50 or 100 jig/g body weight (bw). In the second part of the study, 3-week-old
turtles were injected once with doses of 250, 1000 or 2500 jig/g bw. There were no differences
in survival, growth, or behavior for hatchlings in the first study, however, several effects were
reported from the second part of the study at doses in the range of 250 to 2,500 jig/g bw. As the
dose increased, so did the plastron length (i.e., ventral section of the shell), carapace length, and
weight. The highest dose group had the lowest survival rate with an LD50 of 500 jig/g bw.
Behavioral effects included slower times of righting behavior and seeking cover. The authors
suggested a NOEL of 100 jig/g bw for slider turtles for survival and behavior.
AX7.2.4.4 Recent Studies on Effects of Lead on Decomposers
In this section, decomposers are defined as being bacteria and other microorganisms.
Many invertebrates are also potentially considered decomposers, but the effects of Pb to
invertebrates have been described in previous sections. There were no toxicity studies located on
the effects of Pb to aquatic decomposers in the time period of interest.
AX7.2.4.5 Summary
Lead in all its forms is known to cause adverse effects in aquatic organisms (Eisler, 2000).
Effects to algal growth have been observed at b concentrations ranging from 100 to
200,000 |ig/L. Clinical signs of Pb toxicity in plants include the deformation and disintegration
of algae cells and a shortened exponential growth phase. Other effects of Pb include a blocking
of the pathways that lead to pigment synthesis, thus affecting photosynthesis, cell cycle and
division, and ultimately resulting in death. The toxicity of Pb to macrophyte growth has been
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studied using Spirodelapolyrhiza, Azollapinnata, and Lemna gibba. Test durations ranged from
4 to 25 days and test concentrations ranged between 49.7 and 500,000 |ig/L.
Waterborne Pb is highly toxic to aquatic organisms, with toxicity varying with the species
and life stage tested, duration of exposure, form of Pb tested, and water quality characteristics.
Among the species tested, aquatic invertebrates, such as amphipods and water fleas, were the
most sensitive to the effects of Pb, with adverse effects being reported as low as 0.45 |ig/L.
Effects concentrations for aquatic invertebrates were found to range from 0.45 to 8000 |ig/L.
Freshwater fish demonstrated adverse effects at concentrations ranging from 10 to >5400 |ig/L,
depending generally upon water quality parameters. Amphibians tend to be relatively Pb tolerant
(Eisler, 2000); however, they may exhibit decreased enzyme activity (e.g., ALAD reduction) and
changes in behavior (e.g., hypoxia response behavior). Lead tends to be more toxic with longer-
term exposures.
The primary focus of this section was on effects at the individual level of organization.
This narrow focus is primarily due to a lack of information on the effects of lead on higher levels
of organization (e.g., populations, communities, and ecosystems). The impact of lead at higher
levels of biological organization should be considered in future reviews of lead toxicity.
In considering these higher levels of organization, cause-effect models and relationships that
examine the roles of life history strategy and optimal foraging theory, community processes and
associated theory, and ecosystem processes and the influences of redundancy/interactions should
be taken into account.
AX7.2.5 Effects of Lead on Natural Aquatic Ecosystems
Introduction
As discussed previously, lead exposure may adversely affect organisms at different levels
of organization, i.e., individual organisms, populations, communities, or ecosystems. Generally,
however, there is insufficient information available for single materials in controlled studies to
permit evaluation of specific impacts on higher levels of organization (beyond the individual
organism). Potential effects at the population level or higher are, of necessity, extrapolated from
individual level studies. Available population, community, or ecosystem level studies are
typically conducted at sites that have been contaminated or adversely affected by multiple
stressors (several chemicals alone or combined with physical or biological stressors). Therefore,
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the best documented links between lead and effects on the environment are with effects on
individual organisms.
This section discusses the effects of Pb on natural aquatic ecosystems. Such effects
include changes in species composition and richness, ecosystem function, and energy flow due to
Pb stress. The format of this section generally follows a conceptual framework for discussing
the effects of a stressor such as Pb on an ecosystem. This conceptual framework was developed
by the EPA Science Advisory Board (Young and Sanzone, 2002). The essential attributes used
to describe ecological condition include landscape condition, biotic condition, chemical and
physical characteristics, ecological processes, hydrology and geomorphology and natural
disturbance regimes. The majority of the published literature pertaining to Pb and aquatic
ecosystems focuses on the biotic condition, one of several essential attributes of an ecosystem as
described in Young and Sanzone (2002). For the biotic condition, the SAB framework identifies
community extent, community composition, trophic structure, community dynamics, and
physical structure as factors for assessing ecosystem health. Other factors for assessing the
biotic condition such as effects of Pb on organs, species, populations, and organism conditions
(e.g., physiological status) were discussed in Sections AX7.2.3 and AX7.2.4.
For natural aquatic ecosystems, the focus of study in the general literature has been on
evaluating ecological stress where the sources of Pb were from urban and mining effluents rather
than atmospheric deposition (Poulton et al., 1995; Deacon et al., 2001; Mucha et al., 2003). The
atmospheric deposition of Pb in remote lakes has been evaluated; however, the direct effects of
Pb on aquatic ecosystems was not evaluated in many cases (Larsen, 1983; Kock et al., 1996;
Allen-Gil et al., 1997; Outridge, 1999; Letter et al., 2002). In other studies, although Pb
deposition was studied, the effects of acid deposition on aquatic life were the focus of the study
and perceived to be more relevant (Mannio, 2001; Nyberg et al., 2001). Finally, the effects of
Pb, other metals, and acidification on phytoplankton have only been inferred based on the
paleolimnolical record (Tolonen and Jaakkola, 1983; Rybak et al., 1989). The statistical
methods used when evaluating the effects of Pb on aquatic ecosystems are important, as more
than one variable may be related to the observed effect. Studied variables include water
hardness, pH, temperature, and physical factors such as embeddedness, dominant substrate, and
velocity. In most cases, single variable statistical techniques were used to evaluate the data.
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However, in other cases multivariate techniques were used. Therefore, where appropriate, some
detail on the statistical methods used is presented.
Although most of the available studies discussed in this section focus on the biotic
condition, one case study examining multiple components of the EPA conceptual framework is
also included. The remainder of this section describes the effects of Pb on the biotic condition.
AX7.2.5.1 Case Study: Coeur d'Alene River Watershed
The Coeur d'Alene River watershed is an area of Idaho impacted by Pb and other metals
from historic mining waste releases. Maret et al. (2003) examined several ecological
components to determine any negative associations with metals and the watershed communities.
The variables examined and associated ecological conditions are presented in Table AX7-2.5.1.
In addition to measurements of non-metal variables (e.g., dissolved oxygen levels, water
temperature and pH, embeddedness), Cd, Pb, and Zn levels were also compared in affected sites
versus reference sites.
Some of the above non-metal variables are important to macroinvertebrate communities.
For example, a stream with highly embedded substrate can have a lower number of individuals
within a species or a different species composition compared to a stream with less embeddedness
(Waters, 1995). Macroinvertebrates from the Ephemeroptera (mayflies), Plecoptera (stoneflies),
and Trichoptera (caddisflies) (EPT) group inhabit the surface of cobble and the interstitial spaces
between and underneath cobble. When substrate is embedded, these interstitial spaces are filled,
leaving less habitat space for EPT taxa. In another example, water temperature is important;
some macroinvertebrates (e.g., stoneflies) are usually only found in cooler water (Harper and
Stewart, 1984).
Of the variables examined only metal concentrations, mine density, site elevation, and
water temperature were significantly different between reference and mine-affected sites.
A Mann-Whitney t-test was used to evaluate statistical differences between reference and
test sites for physical and water quality parameters, while Spearman's rank correlation matrices
were used to compare all possible response and explanatory variables. Lead concentrations were
significantly correlated with the number of mines in proximity to the watershed. Lead
concentrations in sediment and water were strongly correlated to Pb levels in whole caddisflies,
r2 = 0.90 and 0.63, respectively. Furthermore, mine density was significantly correlated to Pb in
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Table AX7-2.5.1. Ecological Attributed Studies by Maret et al. (2003)
in the Coeur d'Alene Watershed
Ecological Attribute
Subcategory
Measure
Landscape condition
Biotic Condition
Chemical/physical
characteristics
Areal extent
landscape pattern
Organism condition
population structure/
dynamics
Chemical/physical
parameters
Ecological processes —
Hydrology/geomorphology Channel morphology
and distribution
Natural disturbance regimes
Basin area (km2)
Production mine density/km2
Caddisfly tissue concentrations (mg/kg)
Number of EPT taxa
Density of EPT individuals (no./m2)
Dissolved oxygen (mg/L)
Specific conductance (|iS/cm)
Water temperature (E EC)
pH
Water hardness (mg/L)
Total NO3 (mg/L)
Total P (mg/L)
Dissolved NH3 (mg/L)
Sediment Cd, Pb, Zn (mg/kg)
Dissolved Cd, Pb, Zn in water (mg/L)
None measured
Site elevation (m)
Stream gradient (%)
Stream discharge (m3/s)
Stream width (m)
Stream depth (m)
Open canopy (%)
Stream velocity (m/s)
Embeddedness (%)
Dominant substrate (mm)
None measured
tissue, r2 = 0.64. Although temperature was significantly different between reference and
mine-affected sites, temperature conditions were concluded to be non-limiting to aquatic life.
For example, reference and mine-affected sites had at least 15 and 13 obligate cold-water taxa,
respectively.
A significant negative correlation between Pb in the water column (0.5 to 30 |ig/L
dissolved) and total taxa richness, EPT taxa richness, and the number of metal-sensitive mayfly
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species was observed. Similar, significant negative correlations were found between sediment
Pb levels (132 to 6252 |ig/g) and the same macroinvertebrate community metrics and caddisfly
tissue levels. Negative correlations were also found between Cd and Zn in the water and
sediment and the macroinvertebrate community metrics. In an analysis of cumulative toxicity,
Pb was judged to be the most significant metal in sediment related to the cumulative toxicity
measured. This study provided multiple lines of evidence (i.e., mine density, metal
concentrations, bioaccumulation in caddisfly tissue and benthic invertebrate assemblage
structure) of the negative impacts of mining in the Coeur d'Alene River, suggesting that Pb (and
other metals) were primary contributors to the effects observed in the Coeur d'Alene River
watershed (Maret et al., 2003).
AX7.2.5.2 Biotic Condition
In an evaluation of the biotic condition, the SAB framework described by Young and
Sanzone (2002) identifies community extent, community composition, trophic structure,
community dynamics, and physical structure as essential ecological attributes for assessing
ecosystem health. The following two sections describe the effects of Pb on community
composition, community dynamics, and trophic structure. To date, no available studies were
located on the effects of Pb on physical structure (e.g., change in riparian tree canopy height,
ecosystem succession).
Ecosystems and Communities, Community Composition
To measure community composition, an inventory of the species/taxa found in the
ecological system must be conducted. According the SAB framework, useful measures of
composition include the total number of species or taxonomic units, their relative abundance,
presence and abundance of native and non-native species, and information on the presence and
abundance of focal or special interest species (Young and Sanzone, 2002). Focal or special
species of interest can be those that play a critical role in ecosystem processes such as flows of
materials or energy within complex food-webs (Young and Sanzone, 2002). Community
composition as assessed in Pb studies has included the following measures.
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• Changes in energy flow or nutrient cycling:
o Increased or decreased respiration or biomass
o Increased or decreased turnover/cycling of nutrients
• Changes in community structure:
o Reduced species abundance (i.e., the total number of individuals of a species within
a given area or community)
o Reduced species richness (i.e., the number of different species present in
a community)
o Reduced species diversity (i.e., a measure of both species abundance and species
richness)
Investigators have evaluated the effects of Pb on aquatic communities through microcosm
and mesocosm studies in natural aquatic systems. Field studies in the general literature have
focused on natural systems that were affected by metal stress from various anthropogenic
sources. In most of those natural systems, the sources evaluated were from direct mining waste
inputs, rather than atmospheric deposition, of Pb. Studies published since the 1986 Lead AQCD
(U.S. Environmental Protection Agency, 1986a) that describe the effects of Pb on natural aquatic
ecosystems are presented below and summarized in Table AX7-2.5.2. Studies included here
evaluated the effects of Pb on watersheds, landscapes, aquatic ecosystems, aquatic communities,
biodiversity, lakes, rivers, streams, estuaries, wetlands, and species interaction.
Aquatic Microcosm Studies
The examination of simulated aquatic ecosystems (i.e., microcosms) provides limited
information on the effects of pollutants on natural systems. Microcosm studies typically focus
on only a few aspects of the natural system and do not incorporate all of the ecological,
chemical, or biological interactions. Nevertheless, a few microcosm studies have been
conducted that indicate potential effects of Pb on the community structure of aquatic ecosystems.
Fernandez-Leborans and Antonio-Garcia (1988) evaluated the effect of Pb on a natural
community of freshwater protozoans in simulated aquatic ecosystems and found a reduction in
the abundance and composition of protozoan species with increasing Pb concentrations (0.05 to
1.0 mg/L) compared to controls. Studies with marine protozoan communities in laboratory
microcosms indicated that waterborne Pb exposure reduced protozoan abundance, biomass, and
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Table AX7-2.5.2. Essential Ecological Attributes for Natural Aquatic Ecosystems Affected by Lead
Condition
Category Species Measures
Biotic Condition
Ecosystems and Protozoan community Reduced species
Communities- abundance and
Community diversity
Composition
Protozoan community Reduced species
abundance
t**J Protist community Reduced species
Cj abundance and
to diversity
o
o
Meiofauna community Reduced abundance
Algal community Increased respiration
Algal community Decreased primary
productivity
Meiobenthic Reduced species
community abundance
Exposure
Medium
Marine water
Freshwater
water
Marine water
Marine
sediment
Freshwater
Freshwater
Marine
sediment
Location
Laboratory microcosm
Laboratory microcosm
Laboratory microcosm
Laboratory microcosm
Domestic water
stabilization pond
Sharana Basaveshwara
Tank, India
Laboratory microcosm
Exposure
Concentrations
0.02- 0.05 mg/L
0.05-1 mg/L
1 mg/L
177mg/kg dw
25-80 mg/L
6-32 mg/L
1343mg/kgdw
1580mg/kgdw
Other
Metals
Present Reference
N Femandez-
Leborans and
Novillo(1992)
N Femandez-
Leborans and
Antonio-Garcia
(1988)
N Femandez-
Leborans and
Novillo(1994)
Y Millward et al.
(2001)
? Jayaraj etal. (1992)
? Jayaraj etal. (1992)
N Austen and
McEvoy(1997)
(primarily nematodes) No effect on
abundance
-------
Table AX7-2.5.2 (cont'd). Essential Ecological Attributes for Natural Aquatic Ecosystems Affected by Lead
X
to
o
Category Species
Macroinvertebrate
community
Macroinvertebrate
community
Macroinvertebrate
community
Fish, crustacean and
macroinvertebrate
community
Chironomid community
Macroinvertebrate
community
Macroinvertebrate
community
Condition
Measures
Lower total
abundance, decreased
taxa, and EPT
richness, larger
percentage of tolerant
species of benthic
macroinvertebrates.
Negatively correlated
with species richness
and diversity indices
Reduced species
abundance
Correlation with
changes in species
abundance and
distribution
Reduced chironomid
richness
Lead in tissues
negatively correlated
with taxa richness,
EPT richness,
chironomid richness,
and species density.
Lead in tissues
negatively correlated
Exposure
Medium
Freshwater
and sediment
Estuary
sediment
Freshwater
sediment
Marine
Sediment
Whole
organism
residue
Whole
organism
residue
Biofilm
residues
Location
Mining sites in the
Upper Colorado Basin
Douro Estuary, Portugal
River 111 and tributaries,
France
Spencer Gulf, South
Australia
New Brunswick, Canada
Clark Fork River, MT
Boulder River, MT
Exposure
Concentrations
<0.001-0.02mg/L
145-850 mg/kg dw
(<63 uM fraction)
0.25-1 92 mg/kg dw
1-16 mg/kg dw
156-5270 mg/kg
dw
40. 3-1, 387 mg/kg
dw (periphyton)
1.6-131 mg/kg dw
(chironomid tissue)
32.2-67.1 mg/kg
dw
32-1 540 mg/kg dw
Other
Metals
Present Reference
Y Deacon et al.
(2001);Mizeand
Deacon (2002)
Y Mucha et al. (2003)
Y Rosso etal. (1994)
Y Ward and Young
(1982);
Ward and
Hutchings(1996)
Y Swansburg et al.
(2002)
Y Poulton et al.
(1995)
Y Rhea et al. (2004)
with EPT richness
and abundance.
-------
Table AX7-2.5.2 (cont'd). Essential Ecological Attributes for Natural Aquatic Ecosystems Affected by Lead
Category
Species
Condition Measures
Exposure
Medium
Location
Exposure
Concentrations
Other
Metals
Present
Reference
X
to
o
to
Macroinvertebrate
Community
Fish Community
Ecosystems and Snails and tadpoles
Communities-
Community
Dynamics and
Trophic Structure
Snails and caddisflies
Fathead minnow
Lead in tissues and Sediment
sediment not correlated and whole
to diversity and organism
richness residue
Lead in tissues and Sediment
sediment not correlated and whole
to diversity and organism
richness residue
Lead affected predator- Sediment
prey interactions
No avoidance of Water
predator by snail.
Caddisfly did respond
to predator
Feeding behavior Water
altered
Aquashicola Creek
tributaries, Palmerton,
PA
Aquashicola Creek
tributaries, Palmerton,
PA
Outdoor mini-
ecosystems
Field microcosm for
snail; in-stream
disturbance for
caddisfly
7.5-59.5 mg/kg dw
(sediment)
0.25-6.03 mg/kg dw
(macroinvertebrates)
7.5-59.5 mg/kg dw
(sediment)
0.1-0.86 mg/kg dw
(fish)
Not cited
27.7-277.6 mg/kg
dw (snail tissue)
223-13,507 mg/kg
dw (caddisfly tissue)
Y Carline and Jobsis
(1993)
Y Carline and Jobsis
(1993)
Y Lefcortetal. (1999)
Laboratory microcosm 0.5-l.Omg/L
Y Lefcort et al. (2000)
N Weber (1996)
American toad No avoidance of lead Water
Mummichog Feeding behavior Water
altered and predator
avoidance affected
Laboratory microcosm 0.5-1 .0 mg/L
Laboratory 0.3-1.0 mg/L
N Steeleetal. (1991)
N Weis and Weis
(1998)
-------
diversity at concentrations of 0.02 to 1.0 mg/L Pb (Fernandez-Leborans and Novillo,
1992, 1994).
Austen and McEvoy (1997) studied the effects of Pb on an estuarine meiobenthic
community (mainly nematodes) in a microcosm setting using sediment samples collected
offshore from England. A multivariate analysis of similarities (ANOSIM) test with square root-
transformed data was used to evaluate differences between treatments and controls. Lead was
found to significantly affect species abundance at 1343 mg/kg dw relative to a control at
56 mg/kg dw, but no significant adverse effects were observed at the highest dose tested,
1580 mg/kg dw. The authors did not attempt to explain why the 1580 mg/kg dw dose was not
significant while the 1343 mg/kg dw dose was. None of the Pb exposures were significantly
different than the controls based on separate univariate tests of abundance, richness, and
diversity. There were no other confounding metals in the Pb tests, as the experiments were with
a single metal dose. In one other mesocosm study, the effects of a mixture of metals (Cu, Cd,
Pb, Hg, and Zn) on a salt marsh meiofaunal community were evaluated (Millward et al., 2001).
After 30-days exposure, significant reductions in copepod, gastropod, and bivalve
abundances were observed at the highest Pb exposure concentration, 177 mg/kg dw. Ostracods
and nematodes were not affected. The authors believed that the response of the meiofauna taxa
to metals was in part due to the various feeding strategies in that deposit feeders were most
affected.
Natural Aquatic Ecosystem Studies
Lead stress in aquatic ecosystems has also been evaluated in natural communities.
Studies examining community-scale endpoints, however, are complex, and interpretation can be
confounded by the variability found in natural systems and the presence of multiple stressors.
Natural systems frequently contain multiple metals, making it difficult to attribute observed
adverse effects to single metals. For example, macroinvertebrate communities have been widely
studied with respect to metals contamination and community composition and species richness
(Winner et al., 1980; Chadwick et al., 1986; Clements, 1994). In these studies, multiple metals
are evaluated and correlations between observed community level effects are ascertained. The
results often indicate a correlation between the presence of one or more metals (or total metals)
and the negative effects observed. While, correlation may imply a relationship between two
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variables, it does not imply causation of effects. The following studies suggest an association
between Pb concentration and an alteration of community structure and function (see summary
in Table AX7-2.6.2):
Reduced Primary Productivity and Respiration
Jayaraj et al. (1992) examined the effects of Pb on primary productivity and respiration in
an algal community of two water bodies. Concentrations of Pb in water (6 to 80 mg/L) were
found to significantly reduce primary productivity and increase respiration. The authors
suggested that increased respiration indicated a greater tolerance to or adaptive mechanisms of
the resident heterotrophs to cope with lead stress.
Alterations of Community Structure
Deacon et al. (2001) studied a macroinvertebrate community in mine-affected waters of
Colorado. Initially, transplanted bryophytes were used to assess whether metals could
bioaccumulate at various mine-affected and unaffected sites (Deacon et al., 2001; Mize and
Deacon, 2002). Lead was bioaccumulated by the bryophytes, and median tissue concentrations
at mine-affected sites (34 to 299 ug/g dw) were higher than at reference sites (2.5 to 14.7 ug/g
dw). Lead concentrations in surface water and sediment ranged from <0.001 to 0.02 mg/L and
145 to 850 mg/kg dw (<63 um fraction), respectively. The same sites were also evaluated for the
effects of various metals on macroinvertebrate communities. Values of total abundance, taxa
richness, mayfly, and stonefly abundance were reduced at mining sites. Lead levels along with
Cd, Cu, and Zn were correlated with reduced abundance and diversity indices.
Macrobenthic communities studied in a Portuguese estuary were affected by Pb at a range
from 0.25 to 192 mg/kg dw (Mucha et al., 2003). Species richness was decreased in areas with
increased Pb concentrations in the sediment. Interpretation of Pb effects was complicated by
other non-metal stressors, namely sediment particle size and organic matter content.
Furthermore, other metals were present (e.g., Al, Cu, Cr, Mn, Zn) and may have affected the
community (Mucha et al., 2003).
The effects of Pb on oligochaetes in the 111 River and its tributaries in France were
evaluated by Rosso et al. (1994). Lead in sediment (5 to 16 ug/g dw at affected sites) was
positively correlated to the abundance of the oligochaete, Nais sp., and negatively correlated to
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Tubificidae abundance. Lead was the only metal that was positively correlated to Nais species,
while other metals were negatively correlated to Tubificidae (Rosso et al., 1994).
The effects of metals and particle size on structuring epibenthic sea grass fauna (fish,
mollusks, crustaceans, and polychaetes) was evaluated near a Pb smelter in South Australia
(Ward and Young, 1982; Ward and Hutchings, 1996). Effluent from the smelter was the primary
source of Pb and other metal contamination. Species richness and composition were evaluated
near the Pb smelter along with metal concentrations in sediment. Lead levels in sediment (up to
5270 mg/kg dw) correlated with negative effects on species richness and composition, while the
other metals evaluated had similar correlations. Therefore, Pb alone could not be identified as
the sole metal causing stress.
Tissue Bioaccumulation Associated with Alterations of Community Structure
Several studies have examined the bioaccumulation of lead in aquatic systems with
indices of community structure and function. A focused study on changes in Chironomidae
community composition in relation to metal mines (New Brunswick, Canada) identified changes
in Chironomidae richness (Swansburg et al., 2002). Lead was not detected (detection limit not
given for any matrix) in the water column at any site. However, Pb levels in periphyton were
significantly higher at mining sites (40.3 to 1387 mg/kg dw) compared to reference sites (not
detected [ND], 33.3 mg/kg dw). Furthermore, Pb in chironomids was significantly higher at
mine-affected sites (1.6 to 131 mg/kg dw) compared to reference sites (ND, 10.2 mg/kg dw).
The concentrations in biota indicate that Pb is mobile and available to the aquatic community
even though water concentrations were undetectable. Chironomidae richness was reduced at the
sites receiving mining effluent containing Pb, Cd, Cu, and Zn.
In another study, macroinvertebrate lead tissue concentrations (32.2 to 67.1 mg/kg dw at
affected sites) collected from the Clark Fork River, Montana correlated negatively with total
richness, EPT richness, and density (Poulton et al., 1995). Mean Pb levels were as high as
67.1 mg/kg dw at sites most affected by lead. However, other metals, including Cd, Cu, and Zn,
also were negatively correlated with total richness and EPT richness. Therefore, attribution of
the observed effects to Pb is difficult, as other metals may be contributing factors.
In Montana, the potential effects of metals on macroinvertebrate communities in the
Boulder River watershed were evaluated (Rhea et al., 2004). Similar to the approach taken by
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Poulton et al. (1995), the effects on richness and abundance of EPT taxa were compared to metal
concentrations in tissue (i.e., biofilm and macroinvertebrates). Lead levels in biofilm (32 to
1540 mg/kg dw) were significantly correlated with habitat scores and macroinvertebrate indices
(e.g., EPT taxa). However, macroinvertebrate tissue Pb levels were not significantly correlated
with macroinvertebrate community level metrics. As with most natural systems with potential
mine impacts, other metals also correlated with community level effects. However, the authors
indicated that Pb concentrations in biofilm appeared to have the most significant impact on
macroinvertebrate metrics.
A detailed investigation of sediment, macroinvertebrates, and fish was conducted for
tributaries in the Aquashicola Creek watershed near a former zinc smelter in Palmerton, PA
(Carline and Jobsis, 1993). The smelter deposited large amounts of Cd, Cu, Pb, and Zn on the
surrounding landscape during its operation from 1898 to 1980. The goal of the study was to
evaluate if there was a trend in the metal levels in sediment, macroinvertebrate and fish tissue,
and community indices going away from the smelter. Sites were chosen, from 7.8 to 24.6 km
from the smelter. There were no clear associations between proximity to the smelter and Pb
levels in sediment, macroinvertebrate tissue, and fish tissue. Furthermore, there were no
associations between proximity to the smelter and macroinvertebrate and fish diversity and
richness. The authors suggested that the transport of metals in the watershed has decreased since
the smelter ceased operation, and thereby no effects were observed.
Ecosystems and Communities, Community Dynamics, and Trophic Structure
As described in the SAB framework, community dynamics include interspecies
interactions such as competition, predation, and succession (Young and Sanzone, 2002).
Measures of biotic interactions (e.g., levels of seed dispersal, prevalence of disease in
populations of focal species) provide important information about community condition. If the
community dynamics are disrupted, then the trophic structure may also be disrupted. According
to the SAB framework, trophic structure refers to the distribution of species/taxa and functional
groups across trophic levels. Measures of trophic structure include food web complexity and the
presence/absence of top predators or dominant herbivores. Therefore, this section discusses how
aquatic species interactions can be affected by Pb. Examples of species interactions can include:
AX7-206
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• Predator-prey interactions (e.g., reduced avoidance of predators)
• Prey consumption rate (e.g., increase or decrease in feeding)
• Species competition (e.g., interference with another species, increased aggressive
behavior)
• Species tolerance/sensitivity (e.g., the emergence of a dominant species due to
contaminant tolerance or sensitivity)
Species interactions are highly relevant to a discussion about the effects of Pb on natural
aquatic ecosystems, because effects on species interactions could potentially affect ecosystem
function and diversity. Some examples of Pb induced changes in species interactions are
presented below (see summary in Table AX7-2.5.2).
Predator-prey Interactions
Lefcort et al. (1999) examined the competitive and predator avoidance behaviors of snails
and tadpoles in outdoor mini-ecosystems with sediment from a metals-contaminated Superfund
site (i.e., Pb, Zn, Cd). Previous investigations of aquatic invertebrates and vertebrates yielded Pb
tissue concentrations of 9 to 3800 mg/kg dw and 0.3 to 55 mg/kg dw, respectively. Several
species interactions were studied in the presence of metal-contaminated sediment:
Snails and tadpoles have similar dietary behaviors. Thus, when placed in the same habitat
they will compete for the same food items and negatively affect one another. However, when
tadpoles exposed to a predator (i.e., through biweekly additions of 20 mL of water from tanks
housing sunfish—10 mL from sunfish-fed snails, 10 mL from sunfish-fed tadpoles) were placed
with snails, the tadpoles reduced sediment ingestion, while snails increased ingestion. Thus,
snails were exposed to greater quantities of metals in sediment.
In an uncontaminated environment, snail recruitment (i.e., reproduction) was reduced in
the presence of tadpoles. The addition of tadpoles increased the competition for food in the form
of floating algae and the snails switched to feeding on algae that grew on the sediment. This
decrease was due to competition alone. The effects on snail recruitment were even higher when
tadpoles, the influence of a predator (i.e., sunfish extract), and metals in the sediment were all
present. However, the predator effect was indirect in that the tadpoles hid in the algal mats
forcing the snails to feed primarily on the benthic algae that grew on the sediment with high
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metal levels. Furthermore, although not significant, Pb levels in snails were higher when
tadpoles and sunfish extract were present than when only metals in the sediment were present.
Finally, snail predator avoidance was assessed. Snails (control and lead-exposed) were
stimulated with a predator indicator (i.e., crushed snails and an extract of crushed snail). Control
snails changed behaviors in the presence of the predator indicator, while exposed snails did not
alter their behavior. The authors suggested that metal exposure caused behavioral changes that
alter competitive interactions and the perception of predators by the snails. Thus, Pb may affect
the predator avoidance response of snails.
In further study, Lefcort et al. (2000) examined the predator avoidance behaviors of snails
and caddisflies. In separate experiments, the avoidance behavior of the snail, Physella
columbiana, and four caddisfly genera (Agrypnia, Hydropsyche, Arctopsyche, Neothremma)
were evaluated. The snails were collected from reference lakes and lakes downstream of the
Bunker Hill Superfund site. The snails from the affected lakes generally had higher cadmium,
Pb, and zinc tissue levels implying previous exposure to these metals. Snail predator avoidance
behavior was tested by exposure to crushed snail extract. Snails from the affected lakes did not
reduce their activity when exposed to the snail extract, implying a reduced predator avoidance.
The lack of response may make the snails at the affected lakes more prone to predation.
The caddisflies were evaluated at 36 sites from six different streams. As with the snails,
the caddisflies from the affected streams had higher cadmium, Pb and zinc tissue levels. The
time for caddisfly larvae to respond (i.e., how long immobile) to disturbance (i.e., lifted from
water for 3 seconds and moved to a new location) was evaluated. There was no correlation
between tissue metal level and any response variable (Lefcort et al., 2000). Therefore, the
authors concluded that preexposure to metals did not reduce predator avoidance for caddisflies.
Weber (1996) examined juvenile fathead minnows exposed to 0, 0.5, or 1.0 ppm Pb in
water during a 2-week preexposure and 2-week testing period (4 weeks total exposure). Feeding
behavior was evaluated by presenting two prey sizes (2-day-old and 7-day-old Daphnia magna).
Control fish began switching from larger, more difficult-to-capture 7-day-old daphnids to
smaller, easier-to-catch 2-day-old prey by day 3. Lead-exposed fish displayed significant
switching at day 3 (at 0.5 ppm) or day 10 (at 1.0 ppm). Thus, exposure to Pb delayed the altering
of prey size choices to less energetically costly prey.
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Lefcort et al. (1998) exposed spotted frogs (Rana luteiventris) to 0.05 to 50 ppm Pb in
water for 3 weeks. High levels of Pb reduced the fright response of tadpoles; suggesting a
reduced avoidance of predators.
Bullfrog larvae exposed to Pb in water (0.78 mg/L) and high or low dissolved oxygen
were monitored for respiratory surfacing behavior (Rice et al., 1999). Larvae had a significantly
increased number of trips to the water surface regardless of oxygen content. Thus, the authors
suggest that Pb may affect oxygen uptake such that larvae are under greater predation pressure
due to increased time spent at the surface.
Weis and Weis (1998) evaluated the effect of Pb exposure on mummichog (Fundulus
heteroclitus) larvae prey capture rate, swimming behavior, and predator avoidance. Prey capture
rates were affected after 4 weeks exposure at 1.0 mg Pb/L. The larvae were also more
vulnerable to predation by grass shrimp (Palaemonetespugio) at 1.0 mg Pb/L. Finally, the
swimming behavior of mummichog larvae was affected at 0.3 and 1.0 mg Pb/L. Once the larvae
were no longer exposed to Pb, they recovered their ability to capture prey and avoid predators.
Clearly, exposure to Pb does affect the predator-prey interactions and the ability of prey to
avoid predators. The effect of Pb on these ecological functions may alter community dynamics.
AX7.2.5.3 Summary
The effects of Pb have primarily been studied in instances of point source pollution rather
than area-wide atmospheric deposition; thus, the effects of atmospheric Pb on ecological
condition remains to be defined. The evaluation of point source Pb within the EPA Ecological
Condition Framework has been examined primarily in relation to biotic conditions. The
available literature focuses on studies describing the effects of Pb in natural aquatic ecosystems
with regard to community composition and species interactions. The effects of Pb on the biotic
condition of natural aquatic systems can be summarized as follows: there is a paucity of data in
the general literature that explores the effects of Pb in conjunction with all or several of the
various components of ecological condition as defined by the EPA. However, numerous studies
are available associating the presence of Pb with effects on biotic conditions.
In simulated microcosms or natural systems, environmental exposure to Pb in water and
sediment has been shown to affect energy flow and nutrient cycling and benthic community
structure. In field studies, Pb contamination has been shown to significantly alter the aquatic
AX7-209
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environment through bioaccumulation and alterations of community structure and function.
Exposure to Pb in laboratory studies and simulated ecosystems may alter species competitive
behaviors, predator-prey interactions, and contaminant avoidance behaviors. Alteration of these
interactions may have negative effects on species abundance and community structure. In
natural aquatic ecosystems, Pb is often found coexisting with other metals and other stressors.
Thus, understanding the effects of Pb in natural systems is challenging given that observed
effects may be due to cumulative toxicity from multiple stressors.
AX7-210
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