United States
Environmental Protection
Agency
EPA-452/R-97-006
December 1997
Air
Mercury Study
Report to Congress
Volume IV:
An Assessment of Exposure
to Mercury in the United States
Office of Air Quality Planning & Standards
and
Office of Research and Development
70032-1-4
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MERCURY STUDY REPORT TO CONGRESS
VOLUME IV:
AN ASSESSMENT OF EXPOSURE TO MERCURY
IN THE UNITED STATES
December 1997
U S. Environmental Protection Agency
Region 5, Library (PL-12J)
77 West Jackson Boulevard, 12tn Floor
Chicago, IL 60604-3590
Office of Air Quality Planning and Standards
and
Office of Research and Development
U.S. Environmental Protection Agency
-------
TABLE OF CONTENTS
Page
U.S. EPA AUTHORS iv
SCIENTIFIC PEER REVIEWERS v
WORK GROUP AND U.S. EPA/ORD REVIEWERS viii
LIST OF TABLES ix
LIST OF FIGURES xiv
LIST OF SYMBOLS, UNITS AND ACRONYMS xv
EXECUTIVE SUMMARY ES-1
1. INTRODUCTION 1-1
2. APPROACH TO EXPOSURE ASSESSMENT 2-1
2.1 Modeling Exposures near Mercury Emissions Sources 2-1
2.1.1 Description of Computer Models 2-1
2.1.2 Estimates of Background Mercury 2-3
2.2 Description of Hypothetical Exposure Scenarios for Humans 2-4
2.2.1 Hypothetical Location Descriptions 2-4
2.2.2 Description of Hypothetical Human Exposure Scenarios 2-5
2.3 Summary of Exposure Parameter Values 2-9
2.4 Emissions Sources 2-12
2.5 Predicted Concentrations in Environmental Media 2-12
3. PREDICTED INDIVIDUAL EXPOSURE 3-1
3.1 Illustration of Exposure Results 3-1
3.1.1 Concentrations in Environmental Media and Biota 3-2
3 1 2. Results for Hypothetical Exposure Scenarios 3-6
3.2 Results of Combining Local and Regional Models - Predicted Human Exposure .... 3-12
3.2.1 Inhalation 3-12
3.2.2 Agricultural Scenarios 3-12
3.2.3 Urban Scenarios 3-37
3.2.4 Fish Ingestion Scenarios 3-37
3.3 Issues Related to Predicted Mercury Exposure Estimates 3-38
3.4 Summary Conclusions 3-39
4. POPULATION EXPOSURE 4-1
4.1 Fish Consumption among the General U.S. Population 4-3
4.1.1 Patterns of Fish Consumption 4-1
4.1.2 Frequency of Consumption of Fish Based on Surveys of Individuals 4-13
4.1.3 Subpopulations with Potentially Higher Consumption Rates 4-22
4.1.4 Summary of Hawaiian Island Fish Consumption Data 4-42
4.1.5 Summary of Alaskan Fish Consumption Data 4-43
4.1.6 Summary of Canadian Data on Mercury Intake from Fish and Marine
Mammals 4-48
4.2 Trends in Fish and Shellfish Consumption in the United States 4-50
4.2.1 Fish and Shellfish Consumption: United States, 1975 to 1995 4-50
4.2.2 Current Market Trends, 1996 4-53
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TABLE OF CONTENTS (continued)
Page
4.2.3 Patterns in Fish and Shellfish Consumption: United States, 1996 4-53
4.2.4 Production Patterns and Mercury Concentrations for Specific Fish and Shellfish
Species 4-57
4.3 Mercury Concentrations In Fish 4-59
4.3.1 National Marine Fisheries Service Data Base 4-59
4.3.2 Mercury Concentrations in Marine Fish 4-66
4.3.3 Freshwater Fish Mercury Data Base 4-70
4.3.4 Mercury Concentrations In Freshwater Fish 4-70
4.3.5 Calculation of Mercury Concentrations in Fish Dishes 4-73
4.4 Intake of Methylmercury from Fish/fish Dishes 4-75
4.4.1 Intakes "per User" and "per Capita" 4-75
4.4.2 Methylmercury Intake from Fish and Shellfish among Women of Child-bearing
Age and Children 4-78
4.4.3 Month-Long Estimates for Consumers 4-82
4.4.4 Habitat of Fish Consumed and Mercury Exposure from Fish of Marine, Estuarine
and Freshwater Origin 4-86
4.4.5 Methylmercury Consumption 4-87
4.5 Conclusions on Methylmercury Intake from Fish 4-87
5. POPULATION EXPOSURES - NON-DIETARY SOURCES 5-1
5.1 Dental Amalgams 5-1
5.2 Occupational Exposures to Mercury 5-1
5.3 Miscellaneous Sources of Mercury Exposure 5-3
5.4 Cases of Mercury Poisoning 5-3
6. COMPARISON OF ESTIMATED EXPOSURE WITH BIOMONITORING 6-1
6.1 Biomarkers of Exposure 6-1
6.2 Biomarkers of Exposure Predictive of Intake of Methylmercury 6-1
6.3 Sample Handling and Analysis of Blood Samples for Mercury 6-2
6.4 Association of Blood Mercury with Fish Consumption 6-2
6.4.1 Half-Times of Methylmercury in Blood 6-2
6.4.2 Fraction of Total Blood Mercury that Is Organic or Methylmercury 6-3
6.4.3 Methylmercury Consumption from Fish and Blood Mercury Values 6-3
6.4.4 North American Reports on Blood Mercury Concentrations 6-4
6.5 Hair Mercury as a Biomarker of Methylmercury Exposure 6-8
6.5.1 Hair Composition 6-8
6.5.2 Hair Mercury Concentrations in North America 6-10
6.6 Conclusions 6-15
6.6.1 Blood Mercury Levels 6-15
6.6.2 Hair Mercury Levels 6-15
7. CONCLUSIONS 7-1
8. RESEARCH NEEDS 8-1
9. REFERENCES 9-1
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TABLE OF CONTENTS (continued)
Page
APPENDIX A EXPOSURE PARAMETER JUSTIFICATIONS A-1
APPENDIX B ESTIMATED NATIONAL AND REGIONAL POPULATIONS OF
WOMEN OF CHILD-BEARING AGE: UNITED STATES, 1990 B-l
APPENDIX C ANALYSIS OF MERCURY LEVELS IN FISH AND SHELLFISH
REPORTED IN NATIONAL MARINE FISHERIES SERVICE SURVEY
OF TRACE ELEMENTS IN THE FISHERY RESERVE C-l
APPENDIX D HUMAN FISH CONSUMPTION AND MERCURY
INGESTION DISTRIBUTIONS D-l
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U.S. EPA AUTHORS
Principal Authors
Kathryn R. Mahaffey, Ph.D.
National Center for Environmental
Assessment - Washington
Office of Research and Development
Washington, DC
Glenn E. Rice
National Center for Environmental
Assessment - Cincinnati
Office of Research and Development
Cincinnati, Ohio
Contributing Author
Jeff Swartout
National Center for Environmental
Assessment - Cincinnati
Office of Research and Development
Cincinnati, Ohio
IV
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SCIENTIFIC PEER REVIEWERS
Dr. William J. Adams*
Kennecott Utah Corporation
Dr. Brian J. Allee
Harza Northwest, Incorporated
Dr. Thomas D. Atkeson
Florida Department of Environmental Protection
Dr. Donald G. Barnes*
U.S. EPA Science Advisory Board
Dr. Steven M. Bartell
SENES Oak Ridge, Inc.
Dr. David Bellinger*
Children's Hospital, Boston
Dr. Nicolas Bloom*
Frontier Geosciences. Inc.
Dr. Mike Bolger
U.S. Food and Drug Administration
Dr. Dallas Burtraw*
Resources for the Future
Dr. Thomas Burbacher*
Unhersity of Washington
Seattle
Dr. James P. Butler
University of Chicago
Argonne National Laboratory
Dr. Rick Canady
Agency for Toxic Substances and Disease
Registry
Dr. Rufus Chancy
U.S. Department of Agriculture
Dr. Joan Daisey*
Lawrence Berkeley National Laboratory
Dr. John A. Dellinger*
Medical College of Wisconsin
Dr. Kim N. Dietrich*
University of Cincinnati
Dr. Tim Eder
Great Lakes Natural Resource Center
National Wildlife Federation for the
States of Michigan and Ohio
Dr. Lawrence J. Fischer*
Michigan State University
Dr. W'jlliam F. Fitzgerald
University of Connecticut
Avery Point
A. Robert Flaak*
U.S. EPA Science Advisory Board
Dr. Katharine Flegal
National Center for Health Statistics
Dr. Bruce A. Fowler*
University of Maryland at Baltimore
Dr. Steven G Gilbert*
Biosupport. Inc.
Dr. Cynthia C. Gilmour*
The Academy of Natural Sciences
Dr. Robert Goyer
National Institute of Environmental Health
Sciences
Dr. George Gray
Harvard School of Public Health
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SCIENTIFIC PEER REVIEWERS (continued)
Dr. Terry Haines
National Biological Service
Dr. Gary Heinz*
Patuxent Wildlife Research Center
Joann L. Held
New Jersey Department of Environmental
Protection & Energy
Dr. Robert E. Hueter*
Mote Marine Laboratory
Dr. Harold E. B. Humphrey*
Michigan Department of Community Health
Dr. James P. Hurley*
University of Wisconsin
Madison
Dr. Joseph L. Jacobson*
Wayne State University
Dr. Gerald J. Keeler
University of Michigan
Ann Arbor
Dr. Ronald J. Kendall*
Clemson University
Dr. Lynda P. Knobeloch*
Wisconsin Division of Health
Dr. Leonard Levin
Electric Power Research Institute
Dr. Steven E. Lindberg*
Oak Ridge National Laboratory
Dr. Genevieve M. Matanoski*
The Johns Hopkins University
Dr. Margaret McDowell
National Center for Health Statistics
Dr. Thomas McKone*
University of California
Berkeley
Dr. Malcolm Meabum
National Oceanic and Atmospheric
Administration
U.S. Department of Commerce
Dr. Michael W. Meyer*
Wisconsin Department of Natural Resources
Dr. Maria Morandi*
University of Texas Science Center at Houston
Dr. Paul Mushak
PB Associates
Dr. Christopher Newland*
Auburn University
Dr. Jerome O. Nriagu*
The University of Michigan
Ann Arbor
Dr. W. Steven Otwell*
University of Florida
Gainesville
Dr. Jozef M. Pacyna
Norwegian Institute for Air Research
Dr. Ruth Patterson
Cancer Prevention Research Program
Fred Gutchmson Cancer Research Center
Dr. Donald Porcella
Electric Power Research Institute
Dr. Deborah C. Rice*
Toxicology Research Center
Samuel R. Rondberg*
U.S. EPA Science Advisory Board
Charles Schmidt
U.S. Department of Energy
Dr. Pamela Shubat
Minnesota Department of Health
Dr. Ellen K. Silbergeld*
VI
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SCIENTIFIC PEER REVIEWERS (continued)
University of Maryland Dr. Valerie Thomas*
Baltimore Princeton University
Dr. Howard A. Simonin* Dr. M. Anthony Verity
NYSDEC Aquatic Toxicant Research Unit University of California
Los Angeles
Dr. Ann Spacie*
Purdue University
Dr. Alan H, Stern
New Jersey Department of Environmental
Protection & Energy
Dr. David G. Strimaitis*
Earth Tech
Dr. Edward B. Swain
Minnesota Pollution Control Agency
*\Vith EPA's Science Advisory Board, Mercury Review Subcommitte
vu
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WORK GROUP AND U.S. EPA/ORD REVIEWERS
Core Work Group Reviewers:
Dan Axelrad, U.S. EPA
Office of Policy, Planning and Evaluation
Angela Bandemehr, U.S. EPA
Region 5
Jim Darr, U.S. EPA
Office of Pollution Prevention and Toxic
Substances
Thomas Gentile, State of New York
Department of Environmental Conservation
Arnie Kuzmack, U.S. EPA
Office of Water
Da\idLayIand. U.S. EPA
Office of Solid Waste and Emergency Response
Karen Levy. U.S. EPA
Office of Policy Analysis and Review
Steve Levy. U.S. EPA
Office of Solid Waste and Emergency Response
Lorraine Randecker. U.S. EPA
Office of Pollution Prevention and Toxic
Substances
Joy Taylor. State of Michigan
Department of Natural Resources
U.S. EPA/ORD Reviewers:
Robert Bellies, Ph.D., D.A.B.T.
National Center for Environmental Assessment
Washington, DC
Eletha Brady-Roberts
National Center for Environmental Assessment
Cincinnati, OH
Annie M. Jarabek
National Center for Environmental Assessment
Research Triangle Park, NC
Matthew Lorber
National Center for Environmental Assessment
Washington, DC
Susan Braen Norton
National Center for Environmental Assessment
Washington, DC
Terry Harvey, D V.M.
National Center for Environmental Assessment
Cincinnati. OH
Vlll
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LIST OF TABLES
Page
2-1 Models Used to Predict Mercury Air Concentrations, Deposition Fluxes and Environmental
Concentrations 2-2
2-2 Percentiles of the Methylmercury Bioaccumulation Factor 2-3
2-3 Inputs to IEM-2M Model for the Two Time Periods Modeled 2-4
2-4 Summary of Human Exposure Scenarios 2-6
2-5 Fish Consumption Rates for Columbia River Tribes 2-8
2-6 Daily Fish Consumption Rates Among Adults Fish Consumption by Columbia River Tribes .. 2-8
2-7 Fish Consumption Rates used in this Study 2-9
2-8 Potential Dependency of Exposure Parameters 2-9
2-9 Default Values of Scenario-Independent Exposure Parameters 2-10
2-10 Values for Scenario-Dependent Exposure Parameters 2-11
2-11 Process Parameters for the Model Plants Considered in the Local Impact Analysis 2-13
2-12 Predicted Mercury Values for Environmental Media at Eastern Site
(Local + RELMAP 50th) 2-15
2-13 Predicted Mercury Values for Environmental Media at Eastern Site
(Local + RELMAP 90th) 2-16
2-14 Predicted Mercury Values in Water Column and Biota for Eastern Site
(Local + RELMAP 50th) 2-17
2-15 Predicted Mercury Values in Water Column and Biota for Eastern Site
(Local + RELMAP 90th) 2-18
2-16 Predicted Mercury Values for Environmental Media at Western Site
(Local + RELMAP 50th) 2-19
2-17 Predicted Mercury Values for Environmental Media at Western Site
(Local + RELMAP 90th) 2-21
2-18 Predicted Mercury Values in Water Column and Biota for Western Site
(Local + RELMAP 50th) 2-22
2-19 Predicted Mercury Values in Water Column and Biota for Western Site
(Local + RELMAP 90th) 2-23
3-1 Predicted Mercury Concentrations after Pre-facility Simulations Performed for Eastern Site . . 3-2
3-2 Modeled results for Large Hospital HMI 3-2
3-3 Predicted Mercury Exposure for Subsistence Farmer Scenario 3-8
3-4 Predicted Mercury Exposure for Rural Home Gardener 3-9
3-5 Predicted Mercury Exposure for Urban Average Scenario 3-10
3-6 Predicted Mercury Exposure for Urban High-end Scenarios 3-10
3-7 Predicted Mercury Exposure for High-end Fish Consumption Scenario 3-11
3-8 Predicted Mercury Exposure for Recreational Angler Scenario 3-12
3-9 Eastern Site RELMAP 50th and 90th Percentiles Predicted Ingestion (mg/kg/day) for
Subsistence Farmer 3-13
3-10 Eastern Site RELMAP 50th and 90th Percentiles Predicted Ingestion (mg/kg/day) for Rural
Home Gardner 3-15
3-11 Eastern Site RELMAP 50th and 90th Percentiles Predicted Ingestion (mg/kg/day) for Urban
Average 3-17
3-12 Eastern Site RELMAP 50th and 90th Percentiles Predicted Ingestion (mg/kg/day) for Urban
High End 3-19
3-13 Eastern Site RELMAP 50th and 90th Percentiles Predicted Ingestion (mg/kg/day) for
Subsistence Fisher 3-21
ix
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LIST OF TABLES (continued)
3-14 Eastern Site RELMAP 50th and 90th Percentiles Predicted Ingestion (mg/kg/day) for
Recreational Angler 3-23
3-15 Western Site RELMAP 50th and 90th Percentiles Predicted Ingestion (mg/kg/day) for
Subsistence Farmer 3-24
3-16 Western Site RELMAP 50th and 90th Percentiles Predicted Ingestion (mg/kg/day) for Rural
Home Gardner 3-26
3-17 Western Site RELMAP 50th and 90th Percentiles Predicted Ingestion (mg/kg/day) for Urban
Average 3-28
3-18 Western Site RELMAP 50th and 90th Percentiles Predicted Ingestion (mg/kg/day) for Urban
High End 3-30
3-19 Western Site RELMAP 50th and 90th Percentiles Predicted Ingestion (mg/kg/day) for
Subsistence Fisher 3-32
3-20 Western Site RELMAP 50th and 90th Percentiles Predicted Ingestion (mg/kg/day) for
Recreational Angler 3-34
3-21 Eastern Site RELMAP 50th and 90th Percentiles Predicted Inhalation 3-35
3-22 Western Site RELMAP 50th and 90th Percentiles Predicted Inhalation 3-36
4-1 Average Serving Size (gms) for Seafood from USD A Handbook # 11 Used to Calculate
Fish Intake by FDA (1978) 4-5
4-2 Fish Species and Number of Persons Using the Species of Fish.
(Adapted from Rupp et al., 1980) 4-6
4-3 Fish Consumption from the NPD 1973-1974 Survey
(Modified from Rupp et al., 1980) 4-6
4-4 Distribution of Fish Consumption for Females by Age*
Consumption Category (gms/day) (from SRI. 1980) 4-7
4-5 CSFII 89-91 Data 4-8
4-6 CSFII 1994 Data Days 1 and 2 4-9
4-7 CSFII 1995 Data Days 1 and 2 4-10
4-8 Fish Consumption (gms) by Season for Respondents Reporting Seafood Consumption
CFSII 1994 Day 1 4-10
4-9 All Age Groups NHANES HI 4-12
4-10 NHANES III Adult Respondents 4-12
4-11 NHANES ffl Child Respondents 4-13
4-12 Consumption of Fish and Shellfish (gms/day), and Self-Reported Body Weight (kg)
in Respondents of the 1989-1991 CSFH Survey. "Per Capita"
Data for All Survey Respondents 4-15
4-13 Consumption of Fish and Shellfish (gms/day), and
Self-Reported Body Weight (kg) in Respondents of the 1989-1991 CSFII Survey 4-15
4-14 Frequency of Fish/Shellfish Ingestion and Percent of Respondents 4-17
4-15a Frequency of Fish and Shellfish Consumption by Percent among
All Adults, Both Genders, Weighted Data, NHANES m 4-18
4-15b Frequency of Fish and Shellfish Consumption by Race/Ethnicity,
Women Aged 15-45 Years, Weighted Data, NHANES m 4-18
4-16a Distribution of the Frequency of Fish and Shellfish Consumption by Race/Ethnicity
All Adults, Both Genders, Weighted Data, NHANES ffl 4-19
4-16b Distribution of the Frequency of Fish and Shellfish Consumption by Race/Ethnicity
Among Adult Women Ages 15-45 Years, Weighted Data, NHANES m 4-19
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LIST OF TABLES (continued)
Page
Classification of Fish Species by Habitat 4-20
Weighted Estimates of Fish and Shellfish Consumed (gms) for Females and Males Aged 15-44
Years Reported in NHANES HI (Per User) 4-21
Weighted Estimates for Fish and Shellfish Consumed (gms) by Female and Male Respondents
Aged 15 44 Years Reported in the NHANES ffl Survey by
Habitat of Species Consumed 4-21
20 Consumption of Fish and Shellfish (gms/day) among Ethnically Diverse Groups 4-24
21 Fish Consumption of an Urban "Subsistent" Group 4-26
-22 High Fish Consumption among Urban Subjects: Case Report 4-26
4-23 Compilation of the Angler Consumption Studies 4-28
4-24 Median Recreation ally Caught Fish Consumption Rate Estimates
by Ethnic Group 4-31
4-25 Freshwater Fish Consumption Estimates of Turcotte (1983) 4-31
4-26 Daily Intake of Sportfish and Total Fish for the Fish-consuming Portion
of the Population Studied by Fiore et al. (1989) 4-32
4-27 Fish Consumption Rate Data for Groups Identified in
Hovinga et al. (1992) as Eaters and Controls 4-33
4-28 Fish Consumption Rates for Maine Anglers 4-34
4-29 Fish Consumption Rates of Florida Anglers Who Receive Food Stamps 4-34
4-30 Fish Consumption by Native U.S. Populations 4-35
4-31 Fish Consumption by Columbia River Tribes 4-39
4-32 Daily Fish Consumption Rates by Adults of Columbia River Tribes 4-39
4-33 Fish Consumption (gms/kg bw/day) by the Tulalip and Squaxin Island Tribes 4-40
4-34 Local Fish Meals Consumed By Time Period for the
Mohawk and Comparison Nursing Mothers 4-41
4-35 Species Composition of Hawaii's Retail Seafood Trade 1981 Purchases 4-43
4-36 Mean Per Capita Harvest of Fish and Marine Mammals (g/day) 4-46
4-37 Estimated Daily Intake of Food and Mercury for Arctic Inuit 4-4?
4-38 Mercury Concentrations (jag Hg/g wet weight) in Traditional Foods Consumed
by Canadian Aboriginal Peoples 4-49
4-39 Estimated Daily Intake of Mercury Using Contaminant Data Base and Dietary Information from
Dene and Inuit Communities in Canada 4-49
4-40 Percent of Fish/Shellfish by Processing Type between 1910 and 1995 4-50
4-41 U.S. Supply of Edible Commercial Fishery Products: 1990 and 1995 4-5 i
4-42 U.S. Annual Per Capita Consumption of Canned Fishery Products: 1990 and 1995
(Pounds Per Capita) , 4-52
4-43 U.S. Annual Per Capita Consumption (in pounds*)
of Certain Fishery Items: 1990 and 1995 4-52
4-44 Ten Most Commonly Reported Fish/Shellfish/Mixed Dishes by Season
CSFII 1994 and CSFII1995 Day 1 Data 4-54
4-45 Regional Popularity of Fish and Shellfish Species 4-56
4-46 Popularity of Fish/Shellfish Species in Restaurants 4-56
4-47 Frequencies of Various Fish and Shellfish Food Types
for Children Ages 1 to 5 and 6 to 11 Years by Gender 4-57
4-48 Summary of Mercury Concentrations in Fish Species
(jag Hg/g fresh weight) 4-40
10 Mercury Concentrations in Marine Finfish 4-67
XI
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LIST OF TABLES (continued)
Page
4-50 Mercury Concentrations in Marine Shellfish 4-68
4-51 Mercury Concentrations in Marine MolJuscan Cephalopods 4-69
4-52 Analyses of Mercury Standard Reference Materials Used by Lowe et al. (1985)
in Support of Analyses of Freshwater Fish 4-69
4-53 Freshwater Fish Mercury Concentrations from Lowe et al,, (1985) 4-71
4-54 Mercury Concentrations in Freshwater Fish
U.S. EPA (1992) and Bahnick et al. (1994) 4-73
4-55 CSFII 89-91 Number of Respondents - AH Age Groups 4-75
4-56 CSFII 89-91 Adult Respondents 4-76
4-57 Contemporary Dietary Surveys 1990s General U.S. Population 4-76
4-58 Per Capita Fish/Shellfish Consumption (gms/day) and
Mercury Exposure (ug/kg body weight/day) From CSFII 89-91
Based on Average of Three 24-Hour Recalls 4-77
4-59 Per Capita Fish/Shellfish Consumption Based on Individual Days of 24-Hour Recall Data
General U.S. Population Surveys 1990s 4-77
4-60 Per User Fish/Shellfish Consumption (grams per day) and Mercury Exposure ((Jg/kg bw/day)
Based on Average of Three 24-Hour Recalls CSFII 89-91 4-78
4-61 "Per User" Intake of Fish and Shellfish (gms/day) and Exposure to Mercury (ug Hg/kg bw/day)
among Individuals Reporting Consumption 4-78
4-62 "Per Capita" Fish/Shellfish Consumption (grams/day) and Mercury Exposure ((Jg/kg bw/day)
Based on Average of Three 24-Hour Dietary Recalls CSFII 89-93 4-79
4-63 "Per User" Fish/Shellfish Consumption (grams/day) and Mercury Exposure (Mg/kg bw/day)
Based on Average of Three 24-Hour Dietary Recalls CSFII 89-91 4-79
4-64 Consumption of Fish and Shellfish (grams/day) and Mercury Exposure (pg Hg/kg bw/day)
among Different Age Categories of Children 4-80
65 Fish and Shellfish Consumption (grams/day) and Mercury Exposure (ug/kg body weight/day)
for Children Aged 14 years and Younger CSFII 89-91 4-80
6 "Per User" Fish and/or Shellfish Consumption (grams/day) and
Mercury Exposure (pg Hg/kg bw/day) by Children ages 14 and Younger 4-81
Consumption of Fish and Shellfish (grams/day) and Mercury Exposure (ug Hg/kg bw/day)
Among Ethnically Diverse Groups 4-81
Month-Long Estimates of Fish and Shellfish Consumption (gms/day)
General Population by Ethnic/Racial Group
National Estimates Based on NHANES ffl Data 4-83
Tonth-Long Estimates of Mercury Exposure (|jg/kgbw/day)
pulation by Ethnic/Racial Group National Estimates Based on NHANES ffl Data 4-83
nth-Long Estimates of Exposure to Fish and Shellfish (gms/day)
Vomen Ages 15 through 44 Years Combined
'butions Based on NHANES III Data 4-84
'-Long Estimates of Mercury Exposure (ug/kgiw/day) for Women Ages 15 through 44
ipopulations Combined National Estimates Based on NHANES ffl Data 4-84
.ong Estimates of Fish/Shellfish Consumption (gms/day)
hildren Ages 3 through 6 Years.
Estimates Based on NHANES ffl Data 4-85
ig Estimates of Exposure to Fish and Shellfish (gms/day) and
i/kgbw/day) among Children Ages 3 through 6 Years.
: mates for Individual Ethnic/Racial Groups
xii
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LIST OF TABLES (continued)
Page
4-73 Exposure of Men Ages 15 to 44 Years to Mercury (\ig Hg/kg bw/day)
from Fish and Shellfish of Marine, Estuarine, and Freshwater Origin 4-86
4-74 Exposure of Women Aged 15-44 Years to Mercury (ug Hg/kg bw/day) from
Fish and Shellfish of Marine, Estuarine, and Freshwater Origin 4-87
5-1 Occupational Standards for Airborne Mercury Exposure 5-2
6-1 Literature Derived Values for Total Mercury Concentrations in Whole Blood 6-3
6-2 Blood Mercury Concentrations Values Reported for the United States 6-5
6-3 Hair Mercury Concentrations (ug Hg/gram hair or ppm) from Residents
of Various Communities in the United States 6-11
6-4 Association of Hair Mercury Concentrations (ug Hg/gram hair) with
Frequency of Fish Ingestion by Adult Men and Women
Living in 32 Locations within 13 Countries 6-14
xni
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LIST OF FIGURES
2-1 Configuration of Hypothetical Water Body and Watershed Relative to Local Source 2-5
4-1 Distribution of Fish Consumption Rates of Various Populations 4-23
xiv
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LIST OF SYMBOLS, UNITS AND ACRONYMS
AC
APCD
ASME
CAA
CaS
cf
CFB
cm
CRF
dscf
dscm
ESP
DSI
EPRI
FFDCA
FFs
FGD
FIFRA
FWS
GACT
GLFCATF
GLNPO
g
gr
HAPs
HC1
Hg
HgCl
Hgl
HgO
HgS
HgSe
HMTA
HVAC
IDLH
INGAA
kg
kW
MACT
MB
MCL
Mg
MSW
MW
MWCs
MWIs
Activated carbon
Air pollution control device
American Society of Mechanical Engineers
Clean Air Act as Amended in 1990
Calcium sulfide
Cubic feet
Circulating fluidized bed
Cubic meter
Capital recovery factor
Dry standard cubic feet
Dry standard cubic meter
Electrostatic precipitator
Dry sorbent injection
Electric Power Research Institute
Federal Food, Drug, Cosmetic Act
Fabric filters
Flue gas desulfurization
Federal Insecticide, Fungicide, Rodenticide Act
U.S. Fish and Wildlife Service
Generally available control technology
Great Lakes Fish Consumption Advisory Task Force
Great Lakes National Program Office
Gram
Grains
Hazardous air pollutants
Hydrochloric acid
Mercury
Mercuric chloride
Mercuric iodide
Mercuric oxide
Mercuric sulfide
Mercuric selenite
Hazardous Materials Transportation Act
Heating, ventilating and air conditioning
Immediately dangerous to life and health
Interstate Natural Gas Association Of America
Kilogram
Kilowatt
Maximum achievable control technology
Mass burn
Maximum contaminant level
Megagram
Municipal solid waste
Megawatt
Municipal waste combustors
Medical waste incinerators
xv
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NaCl
NaOH
ng
NIOSH
Nm3
NOAA
NPDES
NSP
NSPS
OAQPS
OECD
O&M
OSHA
PCBs
PELs
PM
ppm
ppmv
RQ
SARA
scf
scm
SD
SDAs
TCC
TCLP
TMT
tpd
TRI
Hg
UNDEERC
WS
ww
LIST OF SYMBOLS, UNITS AND ACRONYMS
(continued)
Sodium chloride
Sodium hydroxide
Nanogram
National Institute for Occupational Safety and Health
Normal cubic meter
National Oceanic and Atmospheric Administration
National Pollutant Discharge Elimination System
Northern States Power
New source performance standard
Office of Air Quality Planning and Standards (U.S. EPA)
Organization for Economic Co-operation and Development
Operation and maintenance
Occupational Safety and Health Administration
Polychlorinated biphenyls
Permissible exposure limits
Paniculate matter
parts per million
parts per million by volume
Reportable quantity
Superfund Amendments and Reauthorization Act
Standard cubic feet
Standard cubic meter
Spray dryer
Spray dryer absorbers
Total capital cost
Toxicity characteristic leaching procedure
Trimercapto-s-triazine
Tons per da\
Toxic Release Inventory
Microgram
University of North Dakota Energy and Environmental Research Center
Wet scrubber
Waterwall
xvi
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EXECUTIVE SUMMARY
Section 112(n)(l)(B) of the Clean Air Act (CAA), as amended in 1990, requires the U.S.
Environmental Protection Agency (U.S. EPA) to submit a study on atmospheric mercury emissions to
Congress. The sources of emissions that must be studied include electric utility steam generating units,
municipal waste combustion units and other sources, including area sources. Congress directed that the
Mercury Study evaluate many aspects of mercury emissions, including the rate and mass of emissions,
health and environmental effects, technologies to control such emissions, and the costs of such controls.
In response to this mandate, U.S. EPA has prepared an eight-volume Mercury Study Report to
Congress. This document is the exposure assessment (Volume IV) of the Mercury Study Report to
Congress. The exposure assessment is one component of the risk assessment of U.S. anthropogenic
mercury emissions. The analysis in this volume builds on the fate and transport data compiled in Volume
III of the study. This exposure assessment considers both inhalation and ingestion exposure routes. For
mercury emitted to the atmosphere, ingestion is an indirect route of exposure that results from mercury
deposition onto soil, water bodies and plants and uptake through the food chain. The analyses in this
volume are integrated with information relating to human and wildlife health impacts of mercury in the
Risk Characterization Volume (Volume VII) of the Report.
National Assessment of Mercury Exposure from Fish Consumption
A current assessment of U.S. general population methylmercury exposure through the
consumption of fish is provided in this volume. This assessment was conducted to provide an estimate of
mercury exposure through the consumption of fish to the general U.S. population. It is not a site-specific
assessment but rather a national assessment. This assessment utilizes data from the Continuing Surveys of
Food Intake by Individuals (CSFII 89-91. CSFII 1994, CSFII 1995) and the third National Heath and
Nutrition Examination Survey (NHANES III) to estimate a range of fish consumption rates among U.S.
fish eaters. Both per capita and per user (only individuals who reported fish consumption) were
considered. For each fish-eater, the number of fish meals, the quantities and species of fish consumed and
the self-reported body weights were used to estimate mercury exposure on a body weight basis. The
constitution of the survey population was weighted to reflect the actual U.S. population. Results of
smaller surveys on "high-end" fish consumers are also included.
These estimates of fish consumption rates were combined with fish species-specific mean values
for measured mercury concentrations. The fish mercury concentration data were obtained from the
National Marine Fisheries Service, Bahnick et al., (1994), and Lowe et al., (1985). Through the
application of specific fish preparation factors (USDA, 1995), estimates of the range of methylmercury
exposure from the consumption of fish were prepared for the fish-consuming segment of the U.S.
population. Per kilogram body weight estimates of methylmercury exposure were determined by dividing
the total daily methylmercury exposure from this pathway by the self-reported body weights.
Estimates of month-long patterns of fish and shellfish consumption were based on the data
reporting frequency of fish/shellfish consumption obtained in the third National Health and Nutrition
Examination Survey (NHANES ffl) conducted between 1988 and 1994. Combining these frequency data
with other information on respondents in NHANES HI (i.e., 24-hour recall data and self-reported body
weight of subjects), and mean mercury concentrations in fish/shellfish, these projected month-long
estimates of fish/shellfish consumption describe moderate-term mercury exposures for the general United
States population.
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Conclusions
The following conclusions are presented in approximate order of degree of certainty in the
conclusion, based on the quality of the underlying database. The conclusions progress from those
with greater certainty to those with lesser certainty.
Consumption of fish is the dominant pathway of exposure to methylmercury for fish-
consuming humans. There is a great deal of variability among individuals in these
populations with respect to food sources and fish consumption rates. As a result, there is
a great deal of variability in exposure to methylmercury in these populations. The
anthropogenic contribution to the total amount of methylmercury in fish is, in part, the
result of anthropogenic mercury releases from industrial and combustion sources
increasing mercury body burdens in fish. As a consequence of human consumption of the
affected fish, there is an incremental increase in exposure to methylmercury.
The critical variables contributing to these different outcomes in measuring exposures are
these:
a) the fish consumption rate;
b) the body weight of the individual in relation to the fish consumption rate;
c) the level of methylmercury found in different fish species consumed; and
d) the frequency offish consumption.
The results of the current exposure of the U.S. population from fish consumption indicate
that most of the population consumes fish and is exposed to methylmercury as a result.
Approximately 85% of adults in the United States consume fish and shellfish at least once
a month with about 40% of adults selecting fish and shellfish as part of their diets at least
once a week (based on food frequency data collected among more than 19,000 adult
respondents in the NHANES III conducted between 1988 and 1994). This same survey
identified 1-2% of adults who indicated they consume fish and shellfish almost daily.
In the nationally-based dietary surveys, the types of fish most frequently reported to be
eaten by consumers are tuna, shrimp, and Alaskan pollock. The importance of these
species is corroborated by U.S. National Marine Fisheries Service data on per capita
consumption rates of commercial fish species.
National surveys indicate that Asian/Pacific Islander-American and Black-American
subpopulations report more frequent consumption of fish and shellfish than other survey
participants.
Superimposed on this general pattern of fish and shellfish consumption is freshwater fish
consumption, which may pose a significant source of methylmercury exposure to
consumers of such fish. The magnitude of methylmercury exposure from freshwater fish
varies with local consumption rates and methylmercury concentrations in the fish. The
modeling exercise indicated that some of these methylmercury concentrations in
freshwater fish may be elevated as a result of mercury emissions from anthropogenic
sources. Exposures may be elevated among some members of this subpopulation; these
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may be evidenced by analyses of blood mercury showing concentrations in excess of 10
micrograms per liter (\igfL) that have been reported among multiple freshwater fish-
consumer subpopulations.
The results of the assessment of current exposure of the U.S. population from fish
consumption as described in this volume. Exposure to methylmercury from contaminated
fish results in an incremental increase in mercury exposure for most U.S. fish-consumers.
Methylmercury exposure rates on a per body weight basis among fish-consuming children
are predicted to be higher than for fish-consuming adults. The 50th percentile exposure
rate among fish-consuming children under the age of 10 and younger is approximately OJ
ug/kg of body weight per day. The 90th percentile predicted exposures are approximately
three times greater or 0.8-1.0 ug/kg body weight/day. The predicted average exposure
among males and females fish consumers of reproductive age is 0.1 ug of methylmercury/
kg body weight/day. Given that these are one-day estimates, it would be inappropriate to
compare these values to the RfD except for subpopulations that eat fish/shellfish almost
every day. Fish consumption rates by adult men and women vary from zero to more than
300 grams per day. These predictions are consistent across the three major contemporary
national food consumption surveys.
Estimated month-long patterns of fish/shellfish intake and mercury exposures indicate that
fish/shellfish consumption is lowest among "White/NonHispanics" (73 grams/day),
second highest among "Black/NonHispanics" (97 grams/day) and highest among the
category designated as "Other" (123 grams/day). The category "Other" includes persons
of Asian/Pacific Islander ethnicity, NonMexican Hispanics (typically persons of Caribbean
ethnicity), Native American tribal members and Native Alaskans, and additional persons.
Based on these estimates of month-long fish/shellfish consumption as the basis for
determining methylmercury exposure, an estimated 97c of the general population exceeds
the RfD.
Among women of childbearing age, 7% exceeded the RfD based on month-long
projections of fish/shellfish intake. Approximately 1 % of women have methylmercury
exposures three-to-four times the RfD. Children in the age group 3-to-6-years have higher
intakes of methylmercury than do adults relative to body weight. Approximately 25% of
children exceed the RfD, and 5<7r of children have methylmercury exposures from
fish/shellfish two-to-three times the RfD (i.e., 0.29 ug/kg body weight/day).
Blood mercury concentrations and hair mercury levels are biomarkers used to indicate
exposure to mercury. Inorganic mercury exposure occur occupationally and for some
individuals through ritualistic/hobby exposures to inorganic mercury. Dental restorations
with silver/mercury amalgams can also contribute to inorganic mercury exposures.
Methylmercury exposure is almost exclusively through consumption of fish, shellfish, and
marine mammals. Occupational exposures to methylmercury are rare.
Normative data describing blood and/or hair mercury for a population representative of the
United States do not exist, however, some data are available. Blood mercury
concentrations in the United States are usually less than 10 ug/L; however, blood mercury
concentrations in excess of 30 ug/L have been reported and are attributed to fish
consumption. Hair mercury concentrations in the United State^ -re typically less than
lug/g, however, hair mercury concentration greater than lOu/g udve been reported for
women of childbearing age living in the United States. U.S. EPA's RfD is associated with
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a blood mercury concentration of 4-5 ug/L and a hair mercury concentration of
approximately lfig/g. The "benchmark" dose is associated with mercury concentrations of
44 ug/L in blood and 11.1 ug/g in hair. The "benchmark" dose for methylmercury is
based on neurotoxic effects observed in Iraqi children exposed in utero to methylmercury.
Specialized smaller surveys of subpopulations including anglers and Native American
Tribal members indicate high fish consumption rates and elevated blood/hair mercury
concentrations occur.
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1. INTRODUCTION
Section 112(n)(l)(B) of the Clean Air Act (CAA), as amended in 1990, requires the U.S.
Environmental Protection Agency (EPA) to submit a study on atmospheric mercury emissions to
Congress. The sources of emissions that must be studied include electric utility steam generating units,
municipal waste combustion units, and other sources, including area sources. Congress directed that the
Mercury Study evaluate many aspects of mercury emissions, including the rate and mass of emissions,
health and environmental effects, technologies to control such emissions, and the costs of such controls.
In response to this mandate, EPA has prepared an eight-volume Mercury Study Report to
Congress. The eight volumes are as follows:
I. Executive Summary
n. An Inventory of Anthropogenic Mercury Emissions in the United States
ID. Fate and Transport of Mercury in the Environment
IV. An Assessment of Exposure to Mercury in the United States
V. Health Effects of Mercury and Mercury Compounds
VI. An Ecological Assessment for Anthropogenic Mercury Emissions in the United States
VII. Characterization of Human Health and Wildlife Risks from Mercury Exposure in the
United States
VIII. An Evaluation of Mercury Control Technologies and Costs
This document is the exposure assessment (Volume IV) of U.S. EPA's Report to Congress on
Mercury. The exposure assessment is one element of the human health and ecological risk assessment of
U.S. anthropogenic mercury (Hg) emissions. The exposure assessment considers both inhalation and
ingestion exposure routes. For atmospheric mercury emissions, ingestion is an indirect route of exposure
that results from mercury deposition onto soil, water bodies and plants and uptake through the food chain.
The information in this document is integrated with information relating to human and wildlife health
impacts of mercury in Volume VII of the report.
Using deposition values obtained from fate and transport models in Volume III, this assessment
addresses the exposures that result from selected, major anthropogenic combustion and manufacturing
sources. This volume also estimates current exposures to the general U.S. population that result from
mercury concentrations in freshwater and marine fish. This volume does not address all anthropogenic
emission sources, nor does it address emissions from natural sources.
Volume IV is composed of nine chapters and three appendices. The Introduction is followed by
Chapter 2, which describes the approach utilized to calculate mercury exposures to humans and wildlife.
Chapter 3 presents estimates of mercury exposure to individuals in the human population and wildlife.
Chapter 4 describes current U.S. exposures through consumption offish. The fish methylmercury
concentrations and the human fish consumption rates were developed using measured data. Exposures
through other routes such as dental amalgams and occupational scenarios are summarized in Chapter 5.
The predicted human exposures are compared to biomonitoring data in Chapter 6.
Chapter 7 presents the conclusions of this Volume. Information needed for better assessment of
exposure to emitted mercury and to current concentrations in media and biota is listed in Chapter 8.
Finally, Chapter 9 lists all references cited in this volume.
There are four appendices to Volume IV: Exposure Parameter Justifications (Appendix A);
Estimated National and Regional Populations of Women of Child-Bearing Age (Appendix B); Analysis of
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Mercury Levels in Fish and Shellfish (Appendix C); and Human Fish Consumption and Mercury
Ingestion Distributions (Appendix D).
The assessment of human mercury exposure through the consumption of fish as described in
Chapter 4 utilizes data from the continuing surveys of food intake by individuals (CSFII 89-91, CSFn
1994, CSFII 1995) and the third National Health and Nutrition Examination Survey (NHANES HI). Both
per capita and per user (only individuals who reported fish consumption) were considered. For each fish-
eater, the number of fish meals, the quantities and species of fish consumed and the self-reported body
weights were used to estimate mercury exposure on a body weight basis. The constitution of the survey
population was weighted to reflect the actual U.S. population. Results of smaller surveys on "high-end"
fish consumers are also included. Continuing Surveys of Food Intake by Individuals (CSFII 89-91) to
estimate a range of fish consumption rates among fish eaters. For each fish-eater, the 3-day CSFn 89-91
study identified the number of fish meals, the quantities and species of fish consumed and the self-reported
body weights of the consumers. The constitution of the survey population was weighted to reflect the
actual U.S. population.
These estimates of fish consumption rates were combined with fish species-specific mean values
for measured methylmercury concentrations. The fish methylmercury concentration data were obtained
from the National Marine Fisheries Service, Bahnick et al., (1994), Lowe et al., (1985), and FDA (1995).
Through the application of specific fish preparation factors (USDA, 1995), estimates of the range of
methylmercury exposure from the consumption of fish were prepared for the fish-consuming segment of
the U.S. population. Per body weight estimates of methylmercury exposure were determined by dividing
the total daily methylmercury exposure from this pathway by the self-reported.
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2. APPROACH TO EXPOSURE ASSESSMENT
This chapter summarizes the methods employed to calculate exposures of humans to
anthropogenic mercury emissions. These methods utilize the predictions of the environmental fate
modeling presented in Volume HI. The models used for the human exposure assessment are identical to
those used for the wildlife exposure assessment (Volume VI of this Report). For the human exposure
modeling analysis, two hypothetical sites in the eastern and western U.S. were developed. The proximity of
these sites to the source was varied to examine the effect of distance on model predictions. To account for
the long-range transport of emitted mercury, the 50th and 90th percentile RELMAP atmospheric
concentrations and deposition rates were included in the estimates from the local air dispersion model. To
account for other sources of mercury, estimates of background concentrations of mercury were also
included in this exposure assessment. Human exposure estimates were developed through the use of
mathematical models and a series of assumptions about human dietary behaviors and ingestion rates. Three
separate exposure sceanrios pertaining to the types and sources of foods consumed were developed.
Parameters that affected hypothetical human exposure are identified in Sections 2.2 and 2.3; some of these
parameters have the potential to change across scenarios. Appendix A describes the specific human
exposure factors utilized in this volume.
2.1 Modeling Exposures near Mercury Emissions Sources
This section summarizes the computer models used to assess mercury exposure resulting from
hypothetical local source emissions; this includes a description of the environmental fate models selected.
Modeling assumptions related to the presence of "background" mercury as well as mercury transported
from other regions of the U.S. are also presented. These models and modeling assumptions are used to
predict exposures of hypothetical humans residing in areas around mercury emission sources.
2.1.1 Description of Computer Models
Atmospheric transport models were used to simulate the deposition of mercury at two different
geographical scales (Table 2-1). A regional-scale analysis was conducted using the Regional Lagrangian
Model of Air Pollution (RELMAP). RELMAP calculates annual mean air concentrations and annual mean
deposition rates for each cell in a 40 km grid. This analysis covered the 48 contiguous states and was
based upon a recent inventory of mercury emissions sources (presented in Volume II of this Report). The
results of the RELMAP model accounted for the long-range transport of mercury emitted from
anthropogenic sources.
The local-scale exposure analysis was conducted by using both RELMAP and a local air transport
model, GAS-ISC3, to generate hypothetical exposure scenarios for four mercury emission source classes.
GAS-ISC3 uses hourly meteorological data to estimate hourly air concentrations and deposition fluxes
within 50 km of a point source. For each hour, general plume characteristics are estimated based on the
source parameters (gas exit velocity, temperature, stack diameter, stack height, wind speed at stack top,
atmospheric stability conditions) for that hour. GAS-ISC3 was run using one year of actual meteorological
data (1989, the same meteorologic year as was utilized in the RELMAP modeling). The average annual
predicted values for air concentration and deposition rates were then used as inputs for to IEM-2M model
for 30 years, the assumed typical lifetime of a facility.
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Table 2-1
Models Used to Predict Mercury Air Concentrations,
Deposition Fluxes and Environmental Concentrations
Model
RELMAP
GAS-ISC3
IEM-2M
Description
Predicts average annual atmospheric mercury concentration and wet
and dry deposition flux for each 40 km2 grid in the U.S. due to all
anthropocentric sources of mercury in the U.S. and a natural
background atmospheric mercury concentration.
Predicts average concentration and deposition fluxes within 50 km of
emission source.
Predicts environmental concentrations based on air concentrations and
deposition rates to watershed and water body.
The IEM-2M model was used to estimate mercury levels in soil, water and biota based on both
regional and local-scale estimates of atmospheric concentrations of mercury and mercury deposition.
IEM-2M is composed of two integrated modules that simulate mercury fate using mass balance equations
describing watershed soils and a shallow lake, IEM-2M simulates three chemical components
elemental mercury, Hg°, divalent mercury, Hgll, and methylmercury, MHg. Mass balances are performed
for each mercury component, with internal transformation rates linking Hg°, Hgll, and MHg. Sources
include wetfall and dryfall loadings of each component to watershed soils and to the water body. An
additional source is diffusion of atmospheric Hg° vapor to watershed soils and the water body. Sinks
include leaching of each component from watershed soils, burial of each component from lake sediments.
volatilization of Hg° and MHg from the soil and water column, and advection of each component out of the
lake.
At the core of EEM-2M are nine differential equations describing the mass balance of each
mercury component in the surficial soil layer, in the water column, and in the surficial benthic sediments.
The equations are solved for a specified interval of time, and predicted concentrations output at fixed
intervals. For each calculational time step, IEM-2M first performs a terrestrial mass balance to obtain
mercury concentrations in watershed soils. Soil concentrations are used along with vapor concentrations
and deposition rates to calculate concentrations in various food plants. These are used, in turn, to calculate
concentrations in animals. IEM-2M simultaneously performs an aquatic mass balance driven by direct
atmospheric deposition along with runoff and erosion loads from watershed soils.
Human exposures through inhalation and ingestion of other contaminated food items (as well as
soils) were also evaluated. Levels of atmospheric mercury were estimated by summing the predicted
concentrations of the RELMAP and GAS-ISC3 models. Soil concentrations were derived directly from
estimates of the IEM-2M model. Concentrations in green plants were estimated using soil-to-plant and air-
to-plant biotransfer factors; mercury in these plants was derived from the local and regional scale air
modeling as well as estimates of background mercury (Section 2.1.2). Estimates of the mercury
concentrations in animal tissues and animal products are generally the product of predicted mercury
concentrations in green plants and soils, animal consumption rates, and specific biotransfer factors.
Mercury in these animals was derived from the local and regional scale air modeling as well as estimates of
background mercury.
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Mercury residues in fish were estimated by making the simplifying assumption that aquatic food
chains can be adequately represented using four trophic levels. Respectively, these trophic levels are the
following: level 1 - phytoplankton (algal producers); level 2 - zooplankton (primary herbivorous
consumers); level 3 - small forage fish (secondary consumers); and level 4 - larger, piscivorous fish
(tertiary consumers), which are eaten by humans. This type of food chain typifies the pelagic assemblages
found in large freshwater lakes, and has been used extensively to model bioaccumulation of hydrophobia
organic compounds (see for example Thomann, 1989; Clark et al., 1990; Gobas, 1993). It is recognized,
however, that food chain structure can vary considerably among aquatic systems resulting in large
differences in bioaccumulation in a given species of fish (Putter, 1994; Cabana et al., 1994a,b). The
second simplifying assumption utilized in this effort was that methylmercury concentrations in fish are
directly proportional to dissolved methylmercury concentrations in the water column. It is recognized that
this relationship can vary widely among both physically similar and dissimilar water bodies.
Methylmercury concentrations in fish were derived from predicted water column concentrations of
dissolved methylmercury by using BAFs for trophic level 4 fish (Table 2-2). The BAFs selected for these
calculations were estimated from existing field data. The BAF (dissolved methylmercury basis) for trophic
level 4 fish is 1.6 x 106, Methylmercury was estimated to constitute 7.8% of the total dissolved mercury in
the water column, and 65% of this was assumed to be freely dissolved. The technical basis for these
estimates is presented in Volume HI, Appendix D. The potential variability around these predicted fish
residue values is highlighted in Table 2-2. Percentile information for the BAF estimates are presented.
Table 2-2
Percentiles of the Methylmercury Bioaccumulation Factor
Parameter
Trophic 4 BAF
Percentile of Distribution
5th
3.3xl06
25th
5.0x10"
50th
6.8xl06
75th
9.2x10"
95th
1.4x 107
2.1.2 Estimates of Background Mercury
In Volume III of this Report it was noted that mercury was a constituent of the environment and
has always been present on the planet. Estimates of atmospheric mercury concentrations and deposition
rates from periods pre-dating large-scale anthropogenic emissions ("pre-anthropogenic") and from current
data were presented for hypothetical eastern and western sites. These estimates were used as inputs to the
IEM-2M model. The equilibrium results of the IEM-2M model were calculated for both the eastern and
western sites and for both the pre-anthropogenic and current time periods. (Chemical equilibrium is
defined here as "a steady state, in which opposing chemical reactions occur at equal rates." (Pauling,
1963)). When modeling the pre-anthropogenic period, the initial conditions of all model compartments
except the atmosphere were set to a mercury concentration of zero. The results of running the pre-
anthropogenic conditions to equilibrium in IEM-2M were used as the initial conditions for estimating the
current mercury concentrations. Table 2-3 lists the estimated mercury air concentrations and deposition
rates used at both hypothetical sites and for both time periods.
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Table 2-3
Inputs to IEM-2M Model for the Two Time Periods Modeled
Time Period
Pre-
Anthropogenic
Current*
Eastern Site
Air Concentration
ng/m3
0.5
1.6
Annual
Deposition Rate
Hg/mVyr
3
10
Western Site
Air Concentration
ng/m3
0.5
1.6
Annual
Deposition Rate
Mg/m2/yr
1
2
: This time period does not reflect the potential contributions of local sources.
2.2 Description of Hypothetical Exposure Scenarios for Humans
In general, exposure scenarios are real or hypothetical situations that define the source of
contamination, the potential receptor populations, the potential pathway(s) of exposure and the variables
that affect the exposure pathways. Mercury exposure in this analysis was assessed for humans residing at
hypothetical locations in the eastern and western United States. The fate of deposited mercury was
examined in three types of settings: rural (agricultural); lacustrine (or water body); and urban. These three
settings were selected because of the variety they encompass and because each is expected to provide a
potentially elevated mercury concentration in environmental media of concern for human exposure; for
example, elevated mercury concentrations are expected in the waters of lakes near mercury emission
sources.
These exposure scenarios included the total amount of food derived from affected areas and the
extent of mercury contamination of these food sources. For an exposure assessment which is, meant to
represent a broad base of potential exposures, it is not practical to model many different types of farms.
gardens, etc. As for the rest of the study, a limited number of representative, generalized types of activities
have been modeled.
2.2.1 Hypothetical Location Descriptions
Mercury exposure is assessed for humans hypothetically located at two generic sites: a humid site
east of 90 degrees west longitude, and a more arid site west of 90 degrees west longitude (these are
described in Volume III). Both sites were assumed to be located in relatively flat terrain. Exposure at each
site was assessed for humans residing at 2.5, 10, or 25 km from the emissions source, as shown in
Figure 2-1. The primary physical differences between the two hypothetical sites as parameterized included
the assumed average annual precipitation rate, the assumed erosion characteristics for the watershed, and
the amount of dilution flow from the water body. The eastern site had generally steeper terrain in the
watershed than was assumed for the western site.
The atmospheric mercury concentration over the hypothetical western site was the sum of the 50th
or 90th percentile of the RELMAP output for the entire contiguous United States west of 90 degrees west
longitude and the GAS-ISC3 prediction resulting from the local source mercury emissions. Similarly, the
mercury concentration over the hypothetical eastern site was the sum of the 50th or 90th percentile of the
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Local
Source
I
Center of lake ar
2.5km,
10km, or
25km
Watershed
Prevailing Downwind Direction
Figure 2-1
Configuration of Hypothetical Water Body and Watershed Relative to Local Source
RELMAP output for the entire contiguous United States east of 90 degrees west longitude and the GAS-
ISC3 prediction resulting from the local source mercury emissions. Deposition to both sites were, similarly,
the sum of the predicted depositions for GAS-ISC3 and the 50th or 90th percentile RELMAP result.
2.2.2 Description of Hypothetical Human Exposure Scenarios
Human exposure to environmental mercury is the result of mercury concentrations at specific
human exposure points (e.g., ingested fish). For each location and setting, mercury exposure was
estimated for individuals representing several specific subpopulations expected to have both typical and
higher exposure levels. The individuals representing the subpopulations were defined to model average
and high-end exposures in the three settings: rural, urban, and lacustrine. In this section each
subpopulation is discussed. A more detailed description of the values chosen for parameters of the
exposure assessment is given in Appendix A. Table 2-4 summarizes the hypothetical scenarios considered
as well as the exposure pathways considered in each scenario.
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Table 2-4
Summary of Human Exposure Scenarios
Air
inhalation
Soil
ingestion
Animal
ingestion
Vegetable
ingestion
Local fish
ingestion
Local water
ingestion
Location
Rural
Subsistence Farmer
Adult
X
X
X
X
X
Child
X
X
X
X
X
Home
Gardener
Adult
X
X
X
Urban
Resident
Adult
X
X
Worker/High-cnd
Adult
X
X
X
Pica
Child
X
X
X
Lacustrine
High End Fisherman
Adult
X
X
X
X
X
Child
X
X
X
X
Rec.
angler
Adult
X
X
X
X
Remote Lakes"
High End Fisherman
Adult
X
X
X
X
Child
X
X
X
Rec.
angler
Adult
X
X
Notes:
" Lakes located greater than 50 km from a mercury emission source
Blank = Pathway not considered
X = Pathway considered.
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2.2.2.1 Rural Exposure Scenarios
Both a high-end and average rural scenario were evaluated. The high-end scenario consisted of a
subsistence farmer and child who consumed elevated levels of locally grown food products. It was
assumed that each farm was located on a square plot of land with an area 40,000 m2 (approximately 10
acres). The subsistence farmer was assumed to raise livestock and to consume home-grown animal tissue
and animal products, including chickens and eggs as well as beef and dairy cattle. All chicken feed was
assumed to be derived from non-local sources. For cattle, 100% of the hay and corn used for feed was
assumed to be from the local area. It was also assumed that the subsistence fanner collected rainwater in
cisterns for drinking. The typical rural dweller was assumed to raise a small garden and derive some of his
food from that source.
2.2.2.2 Urban Exposure Scenarios
In the urban high end scenario, it was assumed that the person had a small garden similar in size to
that of the average rural scenario. To address the fact that home-grown fruits and vegetables generally
make up a smaller portion of the diet in urban areas, the contact fractions were based on weight ratios of
home-grown to total fruits and vegetables consumed for city households. These fractions can be up to 10
times smaller than the values for rural households, depending on food plant type (see Table 2-4 and
Appendix A). Exposure duration for inhalation was 24 hours per day. The high-end urban scenario
included a pica child.
An average urban scenario consisted of an adult who worked outside of local area. The exposure
duration for inhalation, therefore, was only 16 hours a day compared to the 24 hours a day for the rural and
high-end urban scenarios. The only other pathway considered for this scenario was ingestion of average
levels of soil.
2.2.2.3 Description of Hypothetical Human Exposure Scenarios for Individuals Using Water
Bodies
The fish ingestion pathway was the dominant source of methylmercury intake in exposure
scenarios wherein the fish ingestion pathway was considered appropriate. For this assessment, three
human fish consumption scenarios were considered for the hypothetical lakes: (1) an adult high-end fish
consumer scenario, in which an individual was assumed to ingest large amounts of locally-caught fish as
well as home-grown garden produce (plant ingestion parameters identical to the rural home gardener
scenario), consume drinking water from the affected water body and inhale the air; (2) a child of a high-
end local fish consumer, assumed to ingest local fish, garden produce, and soil as well as inhale the
affected air; and (3) a recreational angler scenario, in which the exposure pathways evaluated were fish
ingestion, inhalation, and soil ingestion. These consumption scenarios were thought to represent identified
fish-consuming subpopulations in the United States.
Fish for human consumption from local water bodies can be derived from many sources including
self-caught, gifts, and grocery and restaurant purchases. For the purposes of this study, all fish consumed
were assumed to originate from the hypothetical lakes, which were considered to represent several small
lakes that might be present in the type of hypothetical locations considered. No commercial distribution of
locally caught fish was assumed; exposure to locally-caught fish was modeled for the three fish-consuming
subpopulations described above.
Fish consumption rates for the three fish-consuming subpopulations were derived from the
Columbia River Inter-Tribal Fish Commission Report (1994). Other estimates of human fish consumption
2-7
-------
rates are reported later in this volume; these estimates highlight the broad variability in consumption rates.
The Columbia River Inter-Tribal Fish Commission Report (1994) estimated fish consumption rates for
members of four tribes inhabiting the Columbia River Basin. The estimated fish consumption rates were
based on interviews with 513 adult tribe members who lived on or near the reservation. The participants
had been selected from patient registrations lists provided by the Indian Health Service. Adults
interviewed provided information on fish consumption for themselves and for 204 children under 5 years
of age.
Fish consumption rates for tribal members are shown in Tables 2-5 and 2-6. The values used in
this study are shown in Table 2-7. The values listed below reflect an annual average, but monthly
variations were also reported. For example, the average daily consumption rate during the two highest
intake months was 107.8 grams/day, and the daily consumption rate during the two lowest consumption
months was 30.7 grams/day. Fish were consumed by over 90% of the surveyed population with only 9%
of the respondents reporting no fish consumption. The maximum daily consumption rate for fish reported
by one member of this group was 972 grams/day. Since most of the population consisted of fish
consumers ("users"), utilization of per capita estimates was considered appropriate.
Table 2-5
Fish Consumption Rates for Columbia River Tribes"
Subpopulation
Total Adult Population, aged 1 8 years and older
Children, aged 5 years and younger
Adult Females
Adult Males
Mean Daily Fish Consumption (g/day)
59
20
56
63
' Columbia River Inter-Tribal Commission. 1994.
Table 2-6
Daily Fish Consumption Rates Among Adults
Fish Consumption by Columbia River Tribes*
Percentile
50th
90th
95th
99th
grams/day
29-32
97-130
170
389
' Columbia River Inter-Tribal Commission, 1994.
2-8
-------
Table 2-7
Fish Consumption Rates used in this Study
Subpopulation
High-end Adult
High-end Child
Recreational Angler
Fish Consumption Rate (g/day)'
60
20
30
' Columbia River Inter-Tribal Commission, 1994.
The fish consumed by humans in both the hypothetical eastern and western sites were obtained
from lakes. The drainage lakes were assumed to be circular with a diameter of 1.78 km and average depth
of 5 m. A 2 cm benthic sediment depth was assumed for the lakes. The watershed area associated with
each lake was 37.3 km2.
2.3 Summary of Exposure Parameter Values
To a large degree, there are only a few parameters that vary across these scenarios. Table 2-8
categorizes exposure parameters as invariant or variant with each scenario. A complete list of the values
used and rationale for these values is given in Appendix A.
Table 2-8
Potential Dependency of Exposure Parameters
Parameters Constant Across Scenarios
Parameters that Potentially Change Across Scenarios
Body weight
Exposure duration
Inhalation rate
Animal and vegetable consumption rates
Adult soil ingestion rates
Drinking water ingestion rates
Fish ingestion rates
Contact fractions for vegetables, animal products, and
water
Contact time for inhalation
Child soil ingestion rates
Table 2-9 shows the default values for the scenario-independent parameters for both the child and
adult receptors, and Table 2-10 shows the default values for the scenario-dependent exposure parameters.
The technical bases for these values are in Appendix A. The hypothetical scenarios are discussed in more
detail in the following sections.
2-9
-------
Table 2-9
Default Values of Scenario-Independent Exposure Parameters
Parameter
Body weight (kg)
Inhalation rate (mVday)
Default Value1
Adult
70
20
Child
17
16
Vegetable consumption rates (g dry weight/kg body weight/day)11
Leafy vegetables
Grains and cereals
Legumes
Potatoes
Root vegetables
Fruits
Fruiting vegetables
0.028
1.87
0.381
0.17
0.024
0.57
0.064
0.008
3.77
0.666
0.274
0.036
0.223
0.12
Animal product consumption rates (g dry weight/kg body weight/day)
Beef (excluding liver)
Beef liver
Dairy
Pork
Poultry
Eggs
Lamb
Soil Ingestion rates (g/day)
Water ingestion rate (L/day)
0.341
0.066
0.599
0.169
0.111
0.073
0.057
0.1
2
0.553
0.025
2.04
0.236
0.214
0.093
0.061
Scenario-
dependent
1
* See Appendix A for details regarding these parameter values
11 DW= dry weight; BW = bodyweight.
2-10
-------
Table 2-10
Values for Scenario-Dependent Exposure Parameters"
Parameter
Fish Ingestion rates (g/day)
Soil Ingestion Rate (g/day)
Contact lime for inhalation (hr/day)
Rural Subsistence
Farmer
Adult
NA'
0 1
24
Child
NA
02
24
Ruial Home
G.mloncr
Adult
NA
(1 1
24
Urban Scenarios
Adult
Resident
NA
0 1
16
Home
Gardener
NA
O.I
24
Pica
Child
NA
75
24
High End Fisher
Adult
60
0 1
24
Child
20
0.2
24
Recreational
Angler
Adult
30
O.I
24
Contact fractions (unitlcss)
Animal products
Leafy vegetables
Grains and cereals
Legumes
Potatoes
Fruits
Fruiting vegetables
Root vegetables
Drinking water*
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
NA
0 058
0 667
OX
022S
02"
0621
0 268
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0026
0.195
05
0031
0076
0117
0.07.1
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0058
0.667
0.8
0225
0233
0623
0.268
1
NA
0.058
0.667
0.8
0.225
0.233
0.623
0.268
1
NA
NA
NA
NA
NA
NA
NA
NA
1
J See Appendix A for more details regarding these values.
h The source of the contaminated drinking water is different for the subsistence farmer and high end fisher scenarios.
1 NA - Not Considered to he Applicable to this assessment For example, urban residents were assumed to eat no locally caught fish. Any fish ingested by this subpopulation was
considered to be contaminated by mercury from outside (he m(xleling domain and. thus, not considered
2-11
-------
Consumption rates, bioconcentration factors, and biotransfer factors may be derived based on tissue (plant,
animal, and dairy) weights on either a wet or dry basis. Wet weight and dry weight are related by this
formula:
Dry Weight = Wet Weight / (1 - moisture content)
It is critical that parameters used together are consistent based on either dry weight or wet weight. Many
plants are nearly 90% water, and a mix of wet and dry weight modeling parameters can result in a ten-fold
error. The fish BAF and fish consumption rates in this Report were calculated using wet weight values.
Consumption rates, plant bioaccumulation factors, and animal biotransfer factors were all based upon dry
weights of tissues.
Animal and plant consumption rates as well as inhalation rates are constant across exposure
scenarios. The contact fraction changes generally across the exposure scenarios. The contact fraction
represents the fraction of locally-grown or affected food consumed. Typically, in exposure assessments the
higher the contact fraction the greater the exposure.
2.4 Emissions Sources
Model plants (hypothetical anthropogenic mercury emissions sources) representing four source
classes were developed to represent a range of mercury emissions sources. The source categories were
selected for the indirect exposure analysis based on their estimated annual mercury emissions or their
potential to be localized point sources of concern. The categories selected were these: municipal waste
combustors (MWCs), medical waste incinerators (MWIs), utility boilers, and chlor-alkali plants. Table
2-11 shows the process parameters assumed for each of these facilities. The characteristics of the facilities
were derived based on typical rather than extreme representations; the facilities are known as model plants
(See Volume II).
2.5 Predicted Concentrations in Environmental Media
High rates of mercury deposition were associated with proximity to industrial sources emitting
substantial levels of divalent mercury (Tables 2-12 and 2-15). Additional factors that contributed to high
local deposition rates include low stack height and slow stack exit gas velocities. In general, predicted
mercury concentrations in environmental media at 2.5 km were higher than levels predicted at 10 or 25
km. This was due primarily to the dilution of the mercury emissions in the atmosphere. Mercury
concentrations in biota also typically demonstrated the same pattern. When the two hypothetical locations
were compared (western and eastern), higher mercury concentrations were predicted to occur in the
environmental media and biota at the eastern location. This was due primarily to higher levels of
precipitation at the eastern site, which tends to remove mercury from the atmosphere. Also, the
assumptions of background mercury are higher for the eastern than the western site. This is also attributed
to the generally higher precipitation rates in the eastern United States.
2-12
-------
Table 2-11
Process Parameters for the Model Plants Considered in the Local Impact Analysis
Model Plant
Large Municipal
Waste
Combustors
Small Municipal
Waste
Combustors
Large
Commercial
HMI
Wasic
Incinerator
(Wctscrubber)
Large Hospital
HMI Waste
Incinerators
(Good
Combustion)
Small Hospital
HMI Waste
Incinerators
(1/4 sec.
Combustion)
Large Hospital
HMI Waste
Incinerators
(Wet Scrubber)
Plant
Si/.c
2,250
tons/day
200
tons/day
1500
Ib/hr
capacity
(1000
Ib/hr
actual)
1000
Ib/hr
capacity
(667
Ib/hr
actual)
100 Ib/hr
capacity
(67 Ib/hr
actual)
1000
Ib/hr
capacity
(667
Ib/hr
actual)
Capacity
(7, ol
year)
90%
90%
88%
39%.
27%
39%
Slack
Height
(I'D
230
140
40
40
40
40
Stack
Diameter
(It)
9.5
5
2.7
2.3
0.9
2.3
Hg
Emission
Rate
(kg/yr)
220
20
4.58
23.9
1.34
0.84
Speciation
Percent
(Hg'VHg'V
Hgp)
60/30/10
60/30/10
33/50/17
2/73/25
2/73/27
33/50/17
Exit
Velocity
(m/sec)
21.9
21.9
9.4
16
10.4
9.0
Exit
Temp.
(°F)
285
375
175
1500
1500
175
2-13
-------
Table 2-11 (continued)
Process Parameters for the Model Plants Considered in the Local Impact Analysis
Model Plant
Small Hospital
HMI Waste
Incinerators
(Wet Scrubber)
Large Coal-fired
Utility Boiler
Medium
Coal-fired
Utility Boiler
Small Coal-fired
Utility Boiler
Medium
Oil-fired Utility
Boiler
Chlor-alkali
plant
Plant
Si/.c
I0()lb/hr
capacity
(67 Ih/hr
actual)
975
Mcgawat
ts
375
Mcgawat
ts
100
Mcgawal
ts
285
Mcgawal
ts
300 tons
chlorine/
H;iv
Capacity
(%of
year)
21%
65%
65%
65%
65%
90%
Slack
Height
(CO
40
732
465
266
290
10
Stack
Diameter
(ft)
0.9
27
18
12
14
0.5
Hg
Emission
Rate
(kg/yr)
0.05
230
90
10
2
380
Speciation
Percent
(Hg"/Hg2V
Hg")
33/50/17
50/30/20
50/30/20
50/30/20
50/30/20
70/30/0
Exit
Velocity
(rn/sec)
5.6
31.1
26.7
6.6
20.7
O.I
Exit
Temp.
(°F)
175
273
275
295
322
Ambie
nt
' Hg" = Elemental Mercury
h Hg2' = Divalent Vapor Phase Mercury
1 Hgp = Particle-Bound Mercury
2-14
-------
Table 2-12
Predicted Mercury Values for Environmental Media at Eastern Site (ISC3 + RELMAP 50th)
50th Percentile
Mant Distance
Variant h l,arge Mnmupal Waste CombuMor 2 ^ kin
10 km
25 km
Variant b Small Municipal Waste Combustor 2 5 km
10 km
25km
-arpe Commercial HM! 2 5 km
10 km
25 km
Urge Hosprlal HMI 2 5 km
in km
25 km
Small Hospital HMI 2 5 km
in km
25 km
l.arge Hospital HMI (wet scrubber) 2 5 kin
10 km
25km
Small Hospilal HMI (wet scrubber) 2 5 km
10 km
25 km
-arge Coal-fired Utility Boiler 2 5 Km
Id km
2S km
Medium Coal-fired Utility Boiler 2 5 km
10 km
25km
Small Coal-fired Utility Boiler 25km
10 km
25 km
Vledium Oil-fired Utility Boiler 2 5 km
10 km
25km
Chlnr-alkali plant 2 5 km
10 km
Air Concentration 7rK«-IMap 7rlSC
ng/mj)
1 71 XX) ')?'/! V7f
1 7I-.+OO 98% 2%
1 71' +00 W<, |7,.
1 7I'.-I 99% 1%
1 7I-+00 ItXM 0%
1 7K+IX) I(X)% 0%
1 7I.+(XI Wf- 1%
1 7l.4tX) IM'/S 07o
1 71 + IW4- 0%
\ 71 +77,. '7,.
1 7K+(X) HXl'/f- 0%
1 7l-,+(X) IW/fc 07n
1 7I-+(X) I007r 0%
1 7r+()0 KXI* 0%
1 7I:.+(X1 I(X)% 0%
1 71 +00 100% 0%
1 71+00 100% 0%
1 7I-.+00 I(X>% 0%
1 7i>oo KH>% a%
4 01 +(X) 42% 58%
? ii>on 7')% 21%
Total l>eposilion %RclMap %ISC
uR/m2/vrl
4 2P.+OI 34% 66%
26I:+OI 57% 43%
1 "F.+Ol 78% 22%
1 9f-:+()l 74% 26%
1 6H+OI 90% 10%
1 5R+OI 97% 1%
1 9I-+OI 76% 24%
1 5P+OI 95% 5%
1 5i;+()| 997o 1%
4 4I-.+OI 33% 67%
2 OI--+01 74% 26%
1 61, +01 92% 8%
1 6P.+OI 88% 12%
1 SI.+01 98% 2%
1 5I-+OI 100% 0%
1 5I-.+OI 94% 6%
1 5I:.+OI 99% 1%
1 5H+OI 100% 0%
1 5I.+OI 100% 0%
1 5I-.+OI 100* 0%
1 5i:+oi 100% 0%
3 OF.+OI 48% 52%
1 7P>01 83% 17%
1 6H+OI 93% 7%
2IH+OI 68% 32%
1 61. +01 89% 11%
1 5I-+OI 94% 6%
1 fil'.+OI 90% 10%
1 5P.+OI %% 4%
1 5E+OI 99% 1%
1 5f;+OI 99% 1%
1 5F.+OI 100% 0%
1 5P.+OI 100% 0%
2 5F.+02 6% 94%
4 6I->OI 32% 6R%
? ?(-Wlt 65% 3S%
Total %Bac %Rel %ISC
Hg Soil kRrou Map
Concent nd
allon In
Infilled
Soil
ng/g)
OE+02 46% 8% 47%
74E+OI 63% 11% 26%
6 IE+01 76% 13% 11%
63E+OI 74% 12% 14%
57E+OI 82% 14% 5%
55E+OI 85% 14% 1%
62E+01 75% 12% 13%
56E+OI 84% 14% 2%
55E+OI 85% 14% 1%
1 IE+02 44% 7% 48%
63E+01 74% 12% 14%
57E+OI 82% 14% 4%
58E+O1 81% 13% 6%
55E+OI 85% 14% 1%
55E+OI 86% 14% 0%
56E+OI 84% 14% 3%
55E+-OI 85% 14% 0%
55E+01 86% 14% 0%
55E+OI 86% 14% 0%
54E+OI 86% 14% 0%
54E+OI 86% 14% 0%
8 1E+O1 58% 10% 3.3%
59E+OI 79% 13% 8%
5.6E+OI 83% 14% 3%
6.6E+OI 71% 12% 18%.
58E+OI 81% 13% 5%
56E+OI 84% 14% 3%
57E+OI 82% 14% 5%
55E+OI 84% 14% 2%
5SE+OI 85% 14% 1%
55E+OI 8S% 14% 1%
55E+OI 86% 14% 0%
S5E+OI 86% 14% 0%
45E+02 10% 2% 88%
1 IE*02 43% 7% 50%
ISHR+Ol M* 11% 20%
2-15
-------
Table 2-13
Predicted Mercury Values for Environmental Media at Eastern Site (ISC3 + RELMAP 90th)
lant Distance
'ananl b Large Municipal Wasic Combustor 2 5 km
10 km
25km
'ananl b Small Municipal Wasic Comhiisior 2 1 km
10 km
25km
.arge Commercial HMI 2 5 km
10 km
25 km
.arge Hospilal HMI 2 5 km
10 km
25 km
irmll Hospital HMI 2 5 km
10 km
2Skm
jrge Hospilal HMI (wet scrubber) 2 5 km
10 km
25 km
imall Hospital HMI (wet scrubber) -1 5 km
10 km
25 km
.arge Coal-fired Utility Boiler 2 5 km
10 km
25 km
leditim Coal-fired Utility Boiler 2 5 km
10 km
25 km
imall Coal-fired Unlily Boiler 2 5 km
10 km
25 km
Medium Oil-fired Utility Boiler 2 5 km
10 km
25 km
'hlor-alkali plant 2 5 km
10 km
90th Perc
Air Cnnrrnlralinn '/rRclMap %ISC
n£/m3)
1 XI +(X> 97',* '7"
1 8h+0fl ')Xr* 2%
1 7F+00 99% 1%
1 71 +(X> 99% 1 %
I7I+(K) I(X>% 0%
1 7F.+00 I(X)% 0%
1 7I-.+00 99* 1%
[ 7i-.+oo 100% 0%
1 71-,+no i% o%
1 XI +(X> <)TH- 1%
i 7i-.+(X) w/ r*
1 7I'.+(X) l(X)'/r ()»
I7I+IX) I(X)% 0%
1 7I.+(X) !(X)'<- 0'^
1 71-,+IX) I(KV<. 0%
1 71 +(XI P(KW 0%
I7I+IX) KX)% O'^i
1 7l't(X) HXI'/f O'/^
1 7l-.fOO I(X)% 0%
1 71 +00 ion% 0%
171+00 IW)'/,. 0%
1 7i +ix) iixr/,, 0%
1 71,+IX) I(X1% 0%
1 7I-+IX) I(XI% 0*
1 71 +00 KXT/r 0%
1 7i +m KX)^. 0%
] 7I.+ 00 IfXW 0^
1 71 t(X> KXW. 07,-
1 71 t(X) KXW ()7r
1 71 +00 IIX)'/n 0%
1 7I-.+IX) I(X)% 07n
1 7I-+IX) 100% 0%
1 7I;+(X) I(X)% 0%
40I"+(X) 41* "i7%
2 21- +1X1 7W 21%
entile
Tola! l>ep»silinn %RclMap %ISC
uR/m2/vr)
5 M-+OI 50% 50%
38R+OI 71% 29%
3111+01 87% 13%
12r+OI 85% 15%
29I-.+OI 95% 5%
2 SlvfOI 98% 2%
12h+OI 85% 15%
2 8b+OI 98% 2%
27F.+OI 99% 1%
5 7F.+OI 48* 52%
3 2F.+OI 84% 16%
2 8P.+OI 96% 4%
2 9K+01 91% 7%
27I-+OI 99% 1%
2 7I>OI 100% 0%
2 8P.+01 97% 3%
2 7F.+OI 100% 0%
2 7F.+OI 100% 0%
2 7F.+OI 100% 0%
27K+OI 100% 0%
27I-+OI 100% 0%
4 3p,+oi 64% 36%
10I-.+OI 90% 10%
2 8I-.+-OI 96% 4%
1 4IX1I 80% 20%
2 9I-+OI 94% 6%
2 81 +01 97% 3%
2911+01 94% 6%
2 8F+OI 98% 2%
2 7U+OI 99% 1%
27K+OI 99% 1%
27F+OI 100% 0%
2 7F.+OI 100% 0%
26F.+02 10% 90%
5 9F.+OI 46% 54%
Total HR Soil %Backgro %Rtl %ISC
Concentration In und Map
Untllled Soil
>*/«>
1 2E+02 38% 24% 38%
95E+OI 49% 31% 20%
8 3F.+OI 56% 35% 8%
85E+OI 55% 35% 10%
79E+OI 59% 37% 3%
77E+OI 61% 38% 1%
84E+OI 55% 35% 9%
77E+OI 60% 38% 2%
77E+01 61% 39% 0%
1 3E+02 37% 23% 40%
85E+OI 55% 35% 10%
78E+OI 60% 38% 3%
80E+OI 59% 37% 4%
77E+OI 61% 38% 1%
76E+OI 61% 39% 0%
78E+OI 60% 38% 2%
76E+OI 61% 39% 0%
76E+OI 61% 39% 0%
76E+OI 61% 39% 0%
76E+OI 61% 39% 0%
76E+OI 61% 39% 0%
1 OE+02 45% 29% 26%
8IE+OI 57% 36% 6%
78E+OI 60% 38% 2%
88E+OI 53% 34% 13%
79E+OI 59% .37% 4%
78E+OI 60% 38% 2%
79E+01 59% 37% 3%
77E+OI 60% 38% 1%
77E+OI 61% 39% 0%
77F.+OI 61% 39% 0%
7.6E+OI 61% 39% 0%
76E+01 61% 39% 0%
48E+02 10% 6% 84%
1 3E+02 36% 23% 41%
-------
Table 2-14
Predicted Mercury Values in Water Column and Biota for Eastern Site
(ISC3 + RELMAP 50th)
f Oth Pprrpntilp
Vanant b Large Municipal Waste
Combustor
Vanant b Small Municipal Waste
lombusior
-arge Commercial HMI
Large Hospital HMI
Small Hospital HMI
-arge Hospital HMI (wet scrubber)
Small Hospital HMI (wet scrubber)
~arge Coal-fired LtiliiN Boiler
Medium Coal-fired Utility Boiler
Small Coal ' >rd Utility Boiler
Medium Oil-fired U'tilit) Boiler
Chlor-alkab plant
25km
10km
25km
25km
10km
25km
25km
10km
25km
25km
10km
25km
25km
10km
25km
2 5 km
10km
25km
2 5 km
10km
25km
2 5km
10km
25 km
25km
10km
25km
2 5km
10km
25km
25km
10km
25km
25km
10km
25km
MHg
Dissolv
ed
Water
Conc.(n
ffl]
1 7E-OJ
1 1E-01
8 9E-02
9 5E-02
8 2E-02
7 9E-02
9 6E-02
8 OE-02
7 8E-02
1 9E-01
9 4E-02
8 1E-02
8.5E-02
7 8E-02
7 8E-02
8 IE-02
7 8E-02
7 7E-02
7 8E-0:
7 7E-02
7 7E-02
1 3E-01
8 6E-02
8 OE-02
1 OE-01
8 3E-02
8 OE-02
8 3E-02
7 9E-02
7 8E-02
7 8E-02
7 8E-02
7 7E-02
1 OE+0
0
1 8E-01
1 OE-01
Tier 4
Fish
MHg
Concent
ration
(ue/e)
1.1E+00
7 6E-01
6 OE-01
6 4E-0!
5 6E-01
5 3E-01
65E-01
5 4E-01
5 3E-01
1 3E+00
64E-01
5 5E-01
5 8E-01
5 3E-01
5 3E-01
5 5E-0)
5 3E-01
5 3E-01
5 1E-01
5 3E-01
5 3E-01
9 1E-OI
5 9E-01
5 5E-01
6 9E-01
5 6E-01
54E-01
56E-01
5 4E-01
5 3E-01
5 3E-01
5 3E-01
5 3E-01
68E+00
1 2E+00
6 8E-01
%Backgro
und
38%
58%
73%
68%
79%
83%
68%
82%
83%
34%
69%
80%
76%
83%
84%
80%
84%
84 %
84%
84%
84%
48%
75%
81%
64%
78%
81%
79%
82%
83%
83%
84%
84%
6%
37%
65%
%Rel
Map
7%
11%
14%
13%
15%
16%
13%
16%
16%
6%
13%
15%
15%
16%
16%
15%
16%
16%
16%
16%
16%
9%
14%
15%
12%
15%
16%
15%
16%
16%
16%
16%
16%
1%
7%
12%
%ISC
54%
31%
13%
18%
6%
2%
19%
3%
1%
60%
18%
5%
9%
1%
0%
4%
1%
09
0%
0%
0%
42%
10%
4%
24%
7%
3%
6%
2%
1%
1%
0%
0%
92%
56%
23%
Total Hg Grain
Concentration
(ng/g)
2.1E+00
2IE+00
2.1E+00
21E+00
21E-KX)
21E+00
2 1E+00
2 1E+00
21E+00
2 1E+00
2 1E+00
2 1E+00
2 1E+00
2 IE+00
2 1E+00
2 1E+00
2 1E+00
2 1E+00
2 1E-KX)
2 1E+00
2 1E-KW
2 1E+00
2 1E+00
2 1E+00
2 1E+00
2 1E+OO
2 lE-t-00
2 JE+00
2 1E+00
21E+00
2 1E+00
21E+00
2 1E+00
45E+00
25E+00
22E+00
%B»c
kgrou
nd
93%
94%
95%
96%
96%
96%
96%
96%
97%
93%
96%
96%
96%
97%
97%
96%
97%
97%
97%
97%
97%
96%
96%
96%
96%
96 9r
96%
96%
96%
97%
97%
97%
97%
44%
79%
90%
%Rel
Map
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
1%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
2%
3%
3%
%ISC
4%
2%
1%
1%
0%
0*
1%
0%
0%
4%
1%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
1%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
54%
18%
7%
2-17
-------
Table 2-15
Predicted Mercury Values in Water Column and Biota for Eastern Site
(ISC3 + RELMAP 90th)
Variant b:Largc Municipal Waste
'ombustor
Variant b Small Municipal Waste
'ombustor
.arge Commercial HM1
.arge Hospital HMI
imall Hospital HMI
^rge Hospital HMI (wet scrubber)
imall Hospital HMI (\\el scrubber)
.arge Coal-fired L'tilit\ Boiler
Medium Coal-fired L'lilit\ Boiler
Imall Coal-fired L'tilm Boiler
Medium Oil-fired Utility Boiler
rhlor-alkali plant
2.5km
10 km
25 km
2.5km
10 km
25 km
25km
10 km
25 km
25km
10 km
25 km
25km
10 km
25 km
25km
10 km
25 km
25km
10 km
25 km
25km
10 km
25 km
25km
10 km
25 km
25km
10 km
25 km
25km
10 km
25 km
25km
10 km
25 km
MHg
Dissolv
cd
Water
Conc.(n
tfl)
20E-01
1 5E-01
1 2E-01
1 3E-01
1 2E-01
1 1E-01
1.3E-01
1 1E-01
1 1E-01
2 3E-01
1 3E-01
1 2E-01
1 2E-01
1 1E-01
1 1E-01
1 2E-01
1 1E-01
1 1E-01
1 1E-01
1 1E-01
1 1E-01
1 7E-01
1 2E-01
1 2E-01
1 4E-01
1 2E-01
1 1E-01
1 2E-01
1 1E-01
1 1E-0!
1 1E-01
1 1E-01
1 1E-01
10E+0
0
2 1E-01
I 4E-01
Tier 4
FUh
MHg
Concent
ration
(U«/I)
14E+00
9 9E-01
84E-01
8.8E-01
8 OE-01
7 7E-01
8 9E-01
7 8E-01
77E-01
1 5E+00
8 8E-01
7 9E-01
8 2E-01
7 7E-01
7 6E-01
7 9E-01
7 7E-01
7 6E-01
76E-OI
7 6E-01
76E-01
1 1E+00
82E-01
7 8E-0!
9 3E-01
8 OE-01
7 8E-01
8 OE-01
7 8E-01
7 7E-01
7 7E-01
7 6E-01
7 6E-01
7.1E+00
I4E+00
92E-01
%Backgro
and
32%
44%
52%
50%
55%
57%
50%
57%
58%
29%
50%
56%
54%
57%
58%
56%
58%
58%
58%
58%
<8%
38%
54%
S6%
48%
55%
57%
55%
57%
58%
58%
58%
58%
6%
31%
48%
%Rel
Map
23%
32%
38%
36%
40%
42%
36%
41%
42%
21%
37%
41%
39%
42%
42%
41%
42%
42%
42%
42%
42%
">X
-------
Table 2-16
Predicted Mercury Values for Environmental Media at Western Site (ISC3 + RELMAP 50th)
50th Percentile
Plant Distance
Variant b Urge Municipal Waste Comhustor 2 5 km
10 km
2'ikm
Variant b'Small Municipal Waste Combuslor 2 5 km
10 km
25km
Jirge Commercial HMI 2 5 km
10 km
2'ikm
Uirge Hospital HMI 2 5 km
10 km
2'ikm
Small Hospital HMI 2 5 km
10 km
25 km
Urge Hospital HMI (wet scrubber) 2 5 km
10 km
2S km
Small Hospital HMI (wet scrubber) 2 5 km
10 km
2'ikm
Urge Coal-fired Utility Boiler 2 5 km
in km
J* km
Medium Coal-fired Utility Boiler 2 5 km
10 km
2* km
Air Comcntnilion %Rc-IMap %\SC
(ng/ni3)
1 71 +(X) ')«'/,. 2%
1 dl +(X) W* 2%
1 61 .+00 W% 1%
1 M +(X) 99% \ %
1 6i;+OO 100% 0%
1 6I-+00 100% 0%
1 6F-+00 W% 1%
1 6FXX) 100% 0%
1 61-xx) loo'* o*
1 71XX) 98* 2%
1 6E+oo w* \%
1 hi XX) 100% 0%
1 fcp+00 I(X)% 0%
i ftixxi KX>% o*
1 6r+oo 100% 0%
1 6I-+00 KX>% 0%
1 61 XX) I(X)% ()%
i 6ixx) 100% 0%
1 filXX) 100%. 0%
i fiixxi 100%. 0%
1 6IXX) 100%. 0%
i ftixx) itxi% 0%
1 61 XX) I(X>% 0%
1 filXX) 100* 0%
1 6IXK1 |(X)% 0%
1 6IXW IW* 0%
1 fil +(XI KMi'f 0%
Total Deposition %RclMap %ISC
(Ug/m2/yr)
20F.+01 11% 89%
1 IP.+OI 20% 80%
56E+00 41% 59%
6 2E+00 18% 62%
3 4E+00 68% 32%
27E+00 87% 13%
6 OF.+OO 38% 62%
28P.+00 83% 17%
2 4F.+00 95% 5%
27P.+OI 9% 91%
59E+00 39% 61%
3 1E+00 71% 29%
19P.+00 59% 41%
2 SE+00 92% 8%
2 4E+00 98% 2%
1 0E+00 77% 23%
2 4FXX) 96% 4%
2 1IXX) 99% 1 %
2 4F.+00 98% 2%
2 3E+00 100% 0%
2 3E+00 100% 0%
5 8P.+00 40% 60%
3 5F.+00 67% 33%
3 3E+00 69% 31%
4 3F.+00 53% 47%
1 7H+00 63% J7%
» 2lf+{X) 7.1* 279^
Total Hg %Bac %Rel %ISC
Soil kgrou Map
Concent nd
ration In
Unlllled
Soil
(ng/g)
38E+01 20% 1% 79%
2 1E+OI 33% 2% 65%
1 3E+OI 56% 4% 40%
1 4E+OI 53* 4% 44%
9.9E+00 76% 5% 18%
8.6E+00 87% 6% 6%
1 4E+01 53% 4% 43%
89E+00 85% 6% 9%
83E+00 91% 6% 2%
48E+OI 16% 1% 83%
1 4E+OI 54% 4% 42%
96E+00 79% 5% 16%
1 IE+01 71% 5% 24%
84E+00 90% 6% 4%
82E+00 93% 6% 1%
92E+00 82% 6% 12%
82E+00 92% 6% 2%
8 IE+<» 93% 6% 0%
82E+00 93% 6% 1%
8.IE+00 93% 6% 0%
8 IE+00 94% 6% 0%
1 4E+01 55% 4% 42%
99E+00 76% 5% 19%
98E+00 78* 5% 17%
1 IE+01 66% 9% 29%
IOE+01 73% 5% 22%
9.j5p|^ 79* }% a \?f>
-------
Table 2-16 (continued)
Predicted Mercury Values for Environmental Media at Western Site (ISC3 + RELMAP 50th)
50th Percentile
Plant Distance
Small Coal-fired Utility Boiler 2 5 km
10 km
25 km
Medium Oil-fired Utility Boiler 25km
10 km
25 km
fhlor-alkali plant 25km
10km
25km
Air Concentration %RolM»p %ISC
(nR/m.l)
1 6I-+00 100% 0%
1 M-+00 100% 0%
1 6114 (X) I(X)% 0%
1 hi +00 100% 0%
1 hi +00 IOO'/, 0%
1 hi +00 100% 0%
1 SI +00 46% .54%
1 'M.+OO 84% 16%
1 71 +(X) W, 6%
Total Deposition %RelMap %ISC
-------
Table 2-17
Predicted Mercury Values for Environmental Media at Western Site (ISC3 -t- RELMAP 90th)
Plant (lislann
Variant h Ixirge Municipal Wasie Oninbustcir 2 5 km
10 km
2<>% 1%
1 71 +OI 69% 31%
8 9F+00 90% 10%
96F.+00 8.1% 17%
8 2R+OO 98% 2%
80F.+00 99% 1%
8 7K+00 92% 8%
8 IF.+OO 99% 1%
8 OF.+OO 100% 0%
80E+00 99% 1%
80K+00 100% 0%
80R+00 100% 0%
1 2F.+OI 69% 31%
9111+00 88% 12%
90H+00 89% 11%
1 OF.+01 80% 20%
9 4F.+00 85% 1 5%
8 9E+00 90% 10%
91E+00 88% 12%
8 5K+00 95% 5%
8 2F.+00 98% 2%
81E+00 99% 1%
8 IK+00 99% 1%
8 OE+00 100% 0%
2.0F.+02 4% 96%
1 OF.+OI 16% 74%
1 4F+OI «% 4J%
Total %Bac %Rel %ISC
HgSoil kgrou Map
Concent nd
ration In
Unfilled
Soil
ng/g)
47E+OI 16% 21% 63%
3.2E+OI 24% 31% 46%
23E+OI 33% 43% 24%
2.4E+OI 32% 41% 27%
1 9E+OI 39% 51% 9%
1 8E+OI 42% 55% 3%
23E+OI 32% 42% 26%
1 8E+01 42% 54% 4%
I.8E+OI 43% 56% 1%
57E+fll 1.3% 17% 70%
2.3E+01 32% 42% 25%
1 9E+OI 40% 52% 8%
2.0E+OI 38% 49% 13%
1 8E+01 43% 55% 2%
I.7E+01 43% 56% 0%
1 9E+OI 41% 53% 6%
1 8E+01 43% 56% 1%
1 7E+01 43% 56% 0%
1 7E+OI 43% 56% 0%
I.7E+OI 44% 56% 0%
1 7E+OI 44% 56% 0%
23E+OI 33% 42% 25%
1 9E+OI 39% 51% 10%
1 9E+OI 40% 52% 9%
2.IE+OI 37% 47% 16%
20E+OI 39% 50% 11%
I.9E+01 40% 52% 8%
1 9E+01 40% 51% 9%
I.8E+OI 42% 54% 4%
1 8E+OI 43% 56% 1%
1 8E+OI 43% 56% 1%
1 7E+OI 43% 56% 1%
1 7E+OI 43% 56% 0%
3.3E+02 2% 3% 95%
54E+OI 14% 18% 68%
27E«)I M% .16* 35%
-------
Table 2-18
Predicted Mercury Values in Water Column and Biota for Western Site
(ISC3 + RELMAP 50th)
50th Percentile
Variant b:Large Municipal Waste
^ombustor
Variant b Small Municipal Waste
'ombusior
.arge Commercial HM1
.arge Hospital HMI
Small Hospital HMI
Large Hospital HMI (wet scrubber)
Small Hospital HMI (wet scrubber)
.arge Coal-fired Utiln\ Boiler
Medium Coal-fired Utility Boiler
Small Coal-fired Utilm Boiler
Medium Oil-fired Unlit) Boiler
Chlor-alkali plant
25km
10 km
25 km
25km
10 km
25 km
25km
10 km
25 km
25km
10 km
25 km
25km
10 km
25 km
25km
10 km
25 km
25km
10 km
25 km
25km
10 km
25 km
25km
10 km
25 km
25km
10 km
25 km
25km
10 km
25 km
25km
10 km
25 km
MHg
Dissdv
ed
Water
Cooc-(n
I/I)
88E-02
55E-02
2 7E-02
3 3E-02
1.9E-02
1 6E-02
3 4E-02
1 7E-02
1 5E-02
1 4E-01
3 1E-02
1 8E-02
2 3E-02
1 5E-02
1 4E-02
1 8E-02
1 5E-02
1 4E-02
1 5E-02
1 4E-02
1 4E-02
3 1E-02
1 9E-02
1 8E-02
2 3E-02
2 OE-O:
1 8E-0:
1 9E-02
1 6E-02
1 5E-02
1 5E-02
1 5E-02
1 4E-02
1 OE+0
0
1 2E-01
3 7E-02
Her 4
Fish
MHg
Concent
ration
(ug/S>
60E-01
3.7E-01
1 9E-01
23E-01
1 3E-01
1 1E-01
23E-01
1 1E-01
1 OE-01
9.6E-01
2 1E-01
1 2E-01
1 5E-01
1 OE-01
9 8E-02
1 2E-01
1 OE-01
9 8E-02
9 9E-02
9 7E-02
9 7E-02
2 1E-01
1 3E-01
1 2E-01
1 5E-01
1 4E-01
1 2E-01
1 3E-OI
1 1E-01
) OE-01
1 OE-01
9 9E-02
9 8E-02
69E+OO
8 OE-01
2 5E-01
%Backgro
und
15%
24%
48%
40%
68%
84%
39%
80%
89%
9%
42%
73%
58%
87%
91%
73%
90%
92%
91%
92%
929r
4 3 9,
70%
73%
58%
66%
M<<
70%
81%
88%
90%
91 9r
92%
1%
11%
36%
%Rel
Map
1%
2%
4%
3%
6%
7*
3%
7%
8%
1%
4%
6%
5%
7%
8%
6%
8%
8%
8%
8%
8%
4%
6%
6%
5%
6%
6%
6%
7%
7%
8%
8%
8%
0%
1%
3%
%ISC
84%
74%
48%
57%
26%
9%
58%
14%
3%
90%
54%
20%
37%
6%
1%
20%
3%
1%
2%
0%
0%
53%
24%
21%
37%
^89f
19%
24 9r
13%
4%
2%
2%
1%
99%
88%
61%
ToUl Hg Grain
Concentration
(ng/g)
1.7E+00
1.7E+00
1 7E+00
1.6E+00
1.6E+OO
1 6E+00
1 6E+00
1 6E+00
1 6E+00
1 7E+00
1 6E+00
1 6E+00
1 6E+00
1 6E+00
1 6E+OO
16E+00
1 6E+00
1 6E+00
1 6E+00
1 6E+00
1 6E+00
1 6E+00
1 6E-KXI
1 6E+00
1 6E+00
1 6E+00
1 6E+00
1 6E+00
1 6E+00
1 6E+00
1 6E+00
1 6E+00
1 6E+OO
37E+00
1 9E+00
1 7E+00
%Bac
kgrou
nd
96%
97%
98%
98%
99%
99%
98%
99%
99%
95%
98%
99%
99%
99%
99%
99%
99%
99%
99%
99%
99%
99%
99%
99%
99%
99%
99%
99%
99%
99%
99%
99%
99%
44%
83%
93%
%Rel
Map
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
17,
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
1%
0%
1%
1%
%ISC
3%
2%
1%
1%
0%
0%
1%
0%
0%
4%
1%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
07<
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
56%
16%
6%
2-22
-------
Table 2-19
Predicted Mercury Values in Water Column and Biota for Western Site
(ISC3 + RELMAP 90th)
Variant b. Large Municipal Wasie
Combustor
Variant b:SmaI] Municipal Waste
Combustor
Large Commercial HMI
Large Hospital HMI
Small Hospital HMI
Large Hospital HMI (wet
scrubber)
Small Hospital HMI (wet
scrubber)
Large Coal-fired Utility Boiler
Medium Coal-fired L'tiliu Boiler
Small Coal-fired Utility Boiler
Medium Oil-fired Utibij Boiler
Chlor-alkab plant
25km
10 km
25 km
25km
10 km
25 km
25km
10 km
25 km
25 km
10 km
25 km
25km
10 km
25 km
25km
10 km
25 km
25km
10 km
25 Ion
25km
10 km
25 km
25km
10 km
25 km
25km
10 km
25 km
25km
10 km
25 km
25km
10 km
25 km
MHg
Dissdv
cd
Water
Cooc,(n
tfl>
1.1E-01
75E-02
4 7E-02
53E-02
3 9E-02
3 5E-02
5 4E-02
3 6E-02
3 5E-02
1 6E-01
5 JE-02
3 8E-02
4 3E-02
3 5E-02
3 4E-02
3 8E-02
3 5E-02
3 4E-02
3 4E-02
3 4E-02
' 4E-02
5 OE-02
3 9E-02
3 8E-02
4 3E-02
4 OE-02
3 8E-02
3 9E-02
3 6E-02
3 5E-02
3 4E-02
3 4E-02
3 4E-02
1 OE-M
0
1 4E-01
5 7E-02
90th
Percentile
Tier 4 %Backgro
Fish
MHg
Concent
ration
7.3E-01
51E-01
3 2E-OI
3 6E-01
27E-01
2 4E-01
3 6E-01
2 5E-01
2 4E-01
1 1E+00
3 5E-01
2 6E-01
2 9E-01
2 4E-01
2 3E-OI
2 6E-01
2 3E-01
2 3E-01
2 3E-01
2 3E-OI
2 3E-OI
3 4E-OI
26E-01
2 6E-01
2 9E-01
2 7E-01
2 6E-01
2 6E-01
2 5E-01
2 4E-01
2 3E-01
2 3E-01
2 3E-01
7 1E+00
94E-01
3 9E-OI
and
12%
18%
28%
25%
34%
37%
25%
36%
38%
8%
26%
35%
31%
38%
38%
35%
38%
39%
38%
39%
39%
26%
34%
3S<^r
31%
33%
35%
34%
36%
38%
38%
38%
38%
1%
10%
23%
%Rcl
Map
19*
28%
45*
39%
53%
59%
39%
58%
61%
13%
41%
55%
49%
60%
61%
55%
61%
61%
61%
61%
61%
42r-r
54%
55%
49 <7C
53%
56%
54%
58%
60%
61%
61%
61%
2%
15%
37%
%ISC
68%
54%
28%
36%
13%
4%
36%
6%
1%
79%
33%
10%
20%
3%
1%
10%
1%
0%
1%
0%
0%
32%
12%
10T<
20%
14%
9%
12%
6%
2%
1%
1%
0%
97%
75%
40%
ToUl Hg Grain
Concentration
(ng/g)
17E+00
1 7E+00
1 7E+00
1 7E+00
1.7E+00
I 7E+00
1 7E+00
1 7E+00
1 7E+00
1 7E+00
1 7E+00
1 7E+00
1 7E+00
1 7E+00
1 7E+00
1 7E+00
1 7E+00
1 7E+00
1 7E+00
1 7E+00
1 7E+00
1 7E+00
1 7E+00
1 7E+00
1 7E+00
1 7E-KX)
1 7E+00
1 7E-KX)
1 7E+00
1 7E-KW
1 7E+00
1 7E+00
1 7E+00
37E+00
20E+00
1 8E+00
%B«c
kgrou
nd
94%
95%
96%
96%
97%
97%
96%
97%
97%
94%
96%
97%
97%
97%
97%
97%
97%
97%
97%
97%
97%
97%
97%
9">%
97%
97%
97%
97%
97%
97%
97%
97%
97%
43%
82%
92%
%Rel
Map
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
?%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
3%
1%
2%
3%
%ISC
3%
2%
J*
1%
0%
0%
1%
0%
0%
4%
1%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
0%
o%
0%
0%
0%
0%
0%
55%
16%
6%
2-23
-------
3. PREDICTED INDIVIDUAL EXPOSURE
Using the three models, RELMAP, ISC3, and IEM-2M as well as the hypothetical exposure
scenarios described in Chapter 2 of this Volume, estimates of exposure to individuals residing around local
emissions sources were developed. This exposure assessment incorporated many variables including types
of emissions sources, activity patterns of exposed individuals, climate and impact of regional atmospheric
mercury. Different combinations of these variables provide for a number of potential outputs. This chapter
initially presents a description of the results for one such combination; this is presented to illustrate how
the other combinations presented were developed. This section is followed by a presentation of the results
of the modeling.
3.1 Illustration of Exposure Results
The purpose of this section is to illustrate the results of the exposure modeling by discussing the
results for one facility, distance and site. For the purpose of illustration, the large hospital HMI without a
wet scrubber is selected in the eastern site, and the RELMAP 50th percentile is used as as an example of
the contribution of regional anthropogenic mercury sources. It is noted that a complete discussion is not
practical for all facilities; there are 144 possible combinations: 12 model plants, 2 sites, 3 distances, and
two possible RELMAP values (50th percentile or 90th percentile). These results demonstrate the impacts
of the exposure assessment assumptions used for the hypothetical populations inhabiting the watershed and
water body. It also provides a forum to discuss the more general features and implications of the exposure
assumptions.
The hospital HMI model plant is assumed to emit a total of 24 kg of mercury a year. Of these
mercury emissions, 73% is divalent mercury vapor, 25 is divalent mercury attached to particulates, and 2%-
is elemental mercury vapor. At 2.5 km from the source, the total area-averaged air concentration is
predicted to be 1.7 ng/m3, of which approximately 3% is predicted to be due to the facility and the rest to
regional sources addressed with the RELMAP. The total mercury deposition rate on the watershed is
predicted to be 44 |ag/nr/yr, with about 70% (30 |ag/nr/yr) due to the facility; the total deposition rate is
the sum of the predictions of RELMAP (50th percentile) and ISC3 at 2.5 km from the facility in the
prevailing downwind direction. The predicted area-averaged deposition rate onto the waterbody, which is
located on the side closest to the facility, is 88 ug/nr/yr.
The air concentration and deposition rates predicted for the facility are combined with the 50th
percentile of the results for the RELMAP model and used as inputs for the IEM-2M model. The initial
conditions assumed are the steady-state results after modeling two different periods of constant depositkm
and air concentration. The first period reflects pre-industrial conditions, in which case a mercury air
concentration of 0.5 ng/m3 and deposition rate of 3 ug/nr/yr are assumed. The second period represents
conditions that exist after the pre-industrial period but before the facility is in operation. The assumed air
concentration was 1.6 ng/m3 and the deposition rate was 10 jag/nr/yr. Table 3-1 shows some of the media
concentrations predicted after these two simulations.
3-1
-------
Table 3-1
Predicted Mercury Concentrations after Pre-facility Simulations Performed for Eastern Site
(these results are used as initial conditions in IEM-2M model for this site)
Watershed soil (ng/g)
Dissolved in water column
(ng/L)
47
0.9
%HgO
0.02
8
%Hg2
98
85
%MHg
2
7
3.1.1 Concentrations in Environmental Media and Biota
The predicted concentrations of the three mercury species considered are summarized for various
environmental media and biota in the Table 3-2.
Table 3-2
Modeled results for Large Hospital HMI
(Humid Site, 2.5 km ) Using ISC3 + RELMAP (East 50th percentile)
Waterbod> Deposition Rate
Hg/m2/yr)
Watershed Air Concentration
ng/m3)
Watershed Deposition Rate
Mg/mi/yr)
Total Mercury Dissolved Surface
A' aier Concentration (ng LI
)issol\ed Meth\lmercur>
:oncentration in water bod> (ng/L)
Tier 3 Fish
Tier 4 Fish
Filled Soil (ng/g)
Jonll soil (ng/g)
Total %RelMap %ISC
8.8E+01 16% 84%
1.7E+00 97% 3%
4.4E+01 33% 67%
29
0 19
3 IE-01
1 3E+00
50E+01
1 1E+02
%Relmap %Background %ISC
69r 34% 60%
6% 34% 60%
6% 34% 60%
1% 93% 6%
7% 44% 48%
'roduce (MS/R dry weight)
jrain
Rool Uptake
Direct Deposition
Air-to-plant
^egumes
Rool Uptake
Direct Deposition
Air-tt>-plant
'otatoes
Rom Uptake
Direct Deposition
Air-to-plant
2.1E-03
22%
0%
78%
2.5E-03
31%
3%
66%
5 1E-03
100%
0%
0%
3% 93% 4%
3% 91% 6%
19f 93% 6%
%Hg2 %MHg
0% 100%
0% 100%
0% 100%
98% 2%
98% 2%
92% 8%
93% 7%
96% 4%
3-2
-------
Table 3-2 (continued)
Modeled results for Large Hospital HMI
(Humid Site, 2.5 km) Using ISC3 + RELMAP (East 50th percentile)
Waterbody Deposition Rate
Mg/m2/yr)
Watershed Air Concentration
ng/m3)
Watershed Deposition Rate
liB/m2/yr)
?oot Vegetables
Root Uptake
Direct Deposition
Air-io-plant
:ruits
Root Uptake
Direct Deposition
Air-to-plant
:ruitmg Vegetables
Root Uptake
Direct Deposition
Air-to-plant
.eafy Vegetables
Root Uptake
Direct Deposition
Air-to-planl
\nimal Products (ue'e dn weight)
ieef
from gram
from Forage
from Silage
from Soil
Seef Li\er
from gram
from Forage
fiom Silage
from San
Dain
from gram
from Forage
from Silage
from Soil
>ork
from gram
from Silage
from Soil
'oultry
from gram
from Sol!
;ggs
from gram
from Soil
Total %RelMap %ISC
8.8E-MU 16% 84%
1.7E+00 97% 3%
4.4E+01 33% 67%
1.9E-03
100%
0%
0%
3.5E-02
3%
1%
96%
3.5E-02
3%
1%
96%
3 4E-02
0%
2%
98%
8 6E-03
0%
71%
20%
9%
2 2E-02
0%
71%
20%
99r
1 1E-02
1%
70%
21%
8%
7.0E-06
12%
81%
7%
1.2E-04
15%
85%
1.2E-04
15%
85%
%Relmap % Background %ISC
1% 93% 6%
4% 92% 4%
4% 92% 4%
4% 91% 5%
4% 86% 10%
4% 86% 10%
4% 87% 9%
4% 89% 7%
7% 52% 41%
7% 52% 41%
%Hst2 %MHs
95% 5%
95% 5%
95% 5%
79% 21%
81% 19%
81% 19%
81% 19%
82% 18%
97% 3%
97% 3%
3-3
-------
Table 3-2 (continued)
Modeled results for Large Hospital HMI
(Humid Site, 2.5 km) Using ISC3 + RELMAP (East 50th percentile)
SVaterbody Deposition Rate
ug/m2/yr)
Watershed Air Concentration
ng/m3)
Watershed Deposition Rate
MR/mO/yr)
-amb
from forage
from Soil
ither Produce (ue/g dry weight)
:orage
Root Uptake
Direct Deposition
Air-to-plant
iilage
Root Uptake
Direct Deposition
Air-to-planl
Total %RelMap %ISC
8.8E+01 16% 84%
1.7E-HX) 97% 3%
4.4E+01 33% 67%
3.9E-03
88%
12%
3.5E-02
0%
4%
96%
3.4E-02
0%
1%
99%
%Rebnap % Background %ISC
4% 84% 11%
4% 90% 6%
4% 92% 4%
%Hx2 %MHc
81% 19%
79% 21%
79% 21%
3.1.1.1
Methylmercury Concentrations in Fish
The methylmercury concentration in the fish is determined by multiplying the dissolved
methylmercury concentration in water by a BAF (derivation is described in Volume 3 Appendix D). The
facility is predicted to account for more than half of the methylmercury in the fish for the waterbody
located 2.5 km from the source. This is not via the deposition of methylmercury itself; rather, it is due to
the deposition of elemental and divalent mercury which is either predicted to be methylated after direct
deposition in the water body, or is methylated in the watershed soil and subsequently flows into the
waterbody via runoff or erosion.
The "background" is predicted to account for approximately one third of the methylmercury
concentration in fish. This background represents the steady-state conditions that are predicted to exist
prior to both the facility and the sources represented in the RELMAP modeling, and are used as initial
conditions in the IEM-2M modeling to predict biota concentrations and human exposure.
In the four-tier trophic food chain model used in this Report, fish were assumed to feed at two
levels. Trophic level 3 fish were assumed to feed on plankton which are predicted to be contaminated with
comparatively low levels of methylmercury. Trophic level 4 fish were assumed to feed on trophic level 3
fish, which have higher methylmercury concentrations than the plankton. The median BAF of 1.6e6 LAg
for trophic level 3 fish was estimated using several sets of data on measured mercury concentrations in fish
and water. The media BAF for trophic level 4 of 6.8e6 L/kg) was estimated by applying a predator-prey
factor (of approximately 5) to the bioaccumulation factor estimated for trophic level 3 fish.
3-4
-------
3.1.1.2 Concentrations in Other Biota
Plant Concentrations
Three routes by which plants can take up mercury are addressed here: root uptake, whereby the
plant is assumed to take up mercury from the soil; direct deposition, whereby the mercury deposited on the
plantshoot from atmospheric deposition transfers to the plant; and air-to-plant transfer, whereby the
mercury in the air is transported through the stomata into the plant. In all cases, at least 79% of the
mercury in the plant products is predicted to be of the divalent form, with the rest being methylmercury.
The mercury in potatoes and root vegetables results solely from root uptake since no air uptake
was assumed to occur for these plants (Appendix B of Volume HI). For leafy vegetables, all the mercury is
predicted to be from air uptake since no root uptake was assumed to occur. For grains, legumes, fruits and
fruiting vegetables the bulk of mercury is also modeled to come from air uptake of elemental mercury and
transformation to other species; note, however, that the air and soil biotransfer factors were calculated
based on a conservative premise that air and soil uptake should be of comparable strength. This was done
because the soil concentrations used for this demonstration are several times lower than the soil
concentrations from the Cappon (1981 and 1987) studies from which the soil BCFs were derived. For
more details pertaining to the plant-soil BCF please see Appendix B of Volume HI.
Generally, the facility is predicted to contribute less than 10% to the total mercury plant
concentration. For the plant types for which air-uptake is assumed to be the primary source of mercury, the
facility contribution is similar to the contribution of the facility to the local air concentrations. For the
plant types that uptake mercury primarily from the soil, it is due to the predicted dynamics of the tilled soil
in which the plants are assumed to be grown.
Hanson et al. (1994) stated that "dry foliar surfaces in terrestrial forest landscapes may not be a net
sink for atmospheric Hg°, but rather as a dynamic exchange surface that can function as a source or sink
dependent on current Hg vapor concentrations, leaf temperatures, surface condition (wet versus dry) and
level of atmospheric oxidants." Similarly, Mosbaek et al. (1988) showed that most of the mercury in leafy
plants is attributable to air-leaf transfer, but that for a given period of time the amount of elemental
mercury' released from the plant-soil system greatly exceeds the amount collected from the air by the
plants. It is also likely that many plants accumulate airborne mercury to certain concentrations, after which
net deposition of elemental mercury does not occur. This is also a function of the large area of uncertainty
in deriving soil-to-plant and air-to-plant BCFs for mercury due to the wide variation in values among
different studies. This is described in Appendix B of Volume HI, Section B.I.2.2, B.I.2.2.1, and
B.l.2.2.2.
In general, the plant uptake of mercury is predicted to be dominated by either root uptake or air-to-
plant transfer. For facilities in which the deposition rate is significantly higher, direct deposition may be a
more important pathway. Similarly, the root uptake pathway may be more important in areas with higher
soil concentrations.
3.1.1.3 Mercury Concentrations in Animal Products
The concentrations in animal products were calculated by multiplying the total daily intake of a
particular species of mercury by a transfer factor that can depend on the animal species and tissue. The
animals considered may be exposed to mercury via four possible pathways: ingestion of contaminated
3-5
-------
grain, forage, silage, or soil. The contribution from these pathways depends on both the predicted
concentration in the plant or soil and the ingestion rate for a particular pathway.
For beef and dairy products, most of the intake of mercury is from forage and silage because these
plants are assumed to make up over 80% of their total diet (see Appendix A). The predicted concentration
for beef liver is slightly higher than that for beef due to a higher transfer factor for beef liver. For poultry
products, most of the mercury exposure is predicted to occur through the ingestion of soil (N.B. the
unfilled soil is assumed to be consumed).
3.1.2. Results for Hypothetical Exposure Scenarios
In this section the predicted biota concentrations are used in conjunction with the hypothetical
exposure scenarios to estimate exposure to the human receptors.
Based on the predicted concentrations in biota and using the hypothetical exposure scenarios
described in the previous sections, the predicted human intake rates for each scenario are shown in
Tables 3-3 through Table 3-8.
In general, exposure to mercury is dominated by indirect exposure for any scenario that includes
an ingestion pathway other than soil. Furthermore, exposure tends to be dominated by either divalent or
methylmercury species rather than elemental mercury. For the agricultural and urban scenarios, divalent
mercury is the dominant form. For the scenarios that include fish ingestion, methylmercury dominates
predicted exposure.
3.1.2.1 Rural Scenarios
For the rural scenarios considered, exposure to divalent mercury accounted for over 90% of the
total mercury exposure. The primary exposure pathway is from plant products which account for 50-70%
of the total mercury exposure. Most of the exposure through plant products is predicted to occur from
consumption of fruits and grains. The rural subsistence farmer receptors are predicted to have about four
times as much exposure to mercury as the rural home gardener.
Exposure to mercury from milk (dairy) dominates exposure from animal products for the high end
rural scenario considered (total of seven types of animal products are assumed to be consumed). These
individuals were assumed not to consume fish; as a consequence, predicted methylmercury exposures are
low.
The local source is predicted to account for less than 10% of the total mercury exposure for the
rural scenarios.
3.1.2.2 Urban Scenarios
For the urban average scenario, the only exposure pathways considered are inhalation and
ingestion of soil. For the urban high end scenario, the ingestion of home grown produce is considered as
well, although with lower contact fractions than for the rural home gardener scenario.
For the urban average scenarios, exposure to mercury from the inhalation route was equal to or
exceeded indirect exposure. The urban high-end scenario included a small garden to the urban average
3-6
-------
scenario, with the result that similar contributions to the total divalent mercury and methylmercury
exposures occurred as for the rural home gardeners. The urban high-end adult receptor had a predicted
mercury exposure of about one-half that of the rural home gardener. The high end urban child scenario
consisted of a pica child assumed to ingest 7.5 grams of soil per day. The exposure rate is then
proportional to the assumed untilled soil concentration, which in this case is 100 ng/g.
3.1.2.3 Fish Ingestion Scenarios
It was assumed that the high-end fish consumer eats fish from the affected freshwater lake on a
daily basis; that is, seasonal consumption rate variation was not addressed. This individual is the most
exposed adult to methylmercury in this assessment, and was predicted to be exposed to approximately
twice the level of methylmercury that the recreational angler is exposed. Fish consumption is predicted to
be the primary source of methylmercury in the diet. The high-end fisher was assumed to consume two
times as much fish as the recreational angler (60 g/day vs. 30 g/day). On a gram per bodyweight basis, the
high-end fish-consuming child was the maximally exposed subpopulation. This is based on the
hypothetical child's fish consumption rate and the bodyweight. and is consistent with the data presented in
the Chapter 4 of this Volume.
For the fish ingestion scenarios, intake of mercury was mainly the methylmercury species.
Although intake of methylmercury via plants and soil is considered in the high-end fish consumption
scenario, it accounts for less than 1 % of the total methylmercury' intake. The recreational angler was
assumed to be exposed to mercury via fish, soil and water consumption. Exposure via soil and water
however, accounted for less than 0.1 % of the total mercury intake.
3-7
-------
Table 3-3
Predicted Mercury Exposure for Subsistence Fanner Scenario
ISC: Large Hospital HMKHumid Site, 2.5 km ) + RELMAP(East 50th percentite)
Subsistence Fanner
mg/kg/day Adult
nhalation
ngestion Total
Ish Ingestion
Water Ingestion
Voduce Ingestion
Grains
Legumes
Potatoes
Root vegetables
Fruits
Fruiting vegetables
Leafy vegetables
Animal Ingestion
Beef
Beef liver
Dairy
Pork
Poultry
Eggs
Lamb
Total
4.9E-07
4.1E-05 0%
0 OE+00 0%
5.0E-07 1%
2.9E-05 71%
4.0E-06 10%
9.5E-07 2%
8.7E-07 2%
4 5E-08 0%
2.0E-05 49%
2.2E-06 5%
9 6E-07 2%
1 1E-05 27%
2 9E-06 7%
1 4E-06 4%
65E-06 16%
1.2E-09 0%
1 4E-08 0%
9 OE-09 0%
22E-07 1%
1 SE-07 0%
%Relmap ^Background %ISC
4% 93% 3%
4% 90% 6%
NA NA NA
25% 56% 18%
4% 92% 4%
3% 93% 4%
3% 91% 6%
1% 93% 6%
1% 93% 6%
4% 92% 4%
4% 92% 4%
4% 9 1 % 5%
4% 86% 9%
4% 86% 10%
4% 869, 10%
4% 87% 9%
4% 89% 7%
7% 52% 41%
7% 52% 41%
4% 84% 1 1 %
7% 44% 48%
9fcHe2 %MHg
0% 0%
90% 10%
NA NA
97% 2%
94% 6%
92% 8%
93% 7%
96% 4%
95% 5%
95% 5%
95% 5%
79% 21%
81% 199,
81% 19%
81% 19%
81% 19%
82% 1 8%
97% 3%
97% 3%
81% 19%
98% 2%
ISC Large Hospital HMKHumid Sue. 2 5 km ) + RELMAP(Easl 50th percentile)
Subsistence Farmer
mg/kg/da> Child
nhalation
Total Ingestion
Fish Ingesnon
Water Ingestion
Produce Ingestion
Grains
Legumes
Potatoes
Root vegetables
Fruits
Fruiting vegetables
Leafy vegetables
Animal Ingestion
Beet
Beef liver
Dairy
Port
Poultry
Eggs
Lamb
Total
1 6E-06
5 3E-05 0%
0 OE+00 0%
1 OE-06 29,
2 3E-05 449,
8 1E-06 15%
1 7E-06 3%
1 4E-06 3%
6 7E-08 0%
7 8E-06 1 5%
4 2E-06 8%
27E-07 1%
2 8E-05 52%
4 8E-06 9%
54E-07 1%
22E-05 41%
1 7E-09 0%
2 6E-08 0%
1 1E-08 0%
2.4E-07 0%
1 2E-06 2%
9,Relmap % Background %ISC
49, 93% 3%
4% 87% 8%
NA NA NA
25% 56% 1 89,
?9, 92% 4%
39, 93% 4%
3% 91% 6%
1% 93% 6%
1% 93% 6%
4% 92% 4%
4% 92% 49r
4% 91% 5%
4% 86% 9%
4% 86% 10%
4% 86% 10%
4% 87% 9%
4% 89% 7%
7% 52% 41%
7% 52% 41%
4% 84% 11%
7
-------
Table 3-4
Predicted Mercury Exposure for Rural Home Gardener
ISC Large Hospital HMKHumid Site, 2.5 km ) + RELMAP(East 50th percemile)
Rural Home Gardener
mg/kgAlay Adult
Inhalation
Ingestion Total
Fish Ingestion
Water Ingestion
Produce Ingestion
Grains
Legumes
Potatoes
Root vegetables
Fruits
Fruiting vegetables
Leafy vegetables
Animal Ingestion
Beef
Beef liver
Dairv
Pork
Poultry
Eggs
Lamb
Soil Ingesnon
Total 1 %Relmap ^Background %ISC
4.9E-07
9.9E-06 0%
O.OE+00 0%
O.OE+00 0%
9.7E-06 98%
2.7E-06 27%
7.6E-07 8%
2.0E-07 2%
1 2E-08 0%
4 6E-06 47%
1 4E-06 14%
55E-08 1%
O.OE+00 0%
0 OE+00 0%
0 OE+00 0%
0 OE+00 0%
0 OE+00 OS
O.OE^OO 0%
0 OE+00 0%
0 OE+00 07,
1 5E-07 27r
4% 93% 3%
4% 91% 5%
NA NA NA
NA NA NA
4% 92% 4%
3% 93% 4%
3% 91% 69t
1% 93% 6%
\9c 93% 6%
4% 92% 4%
4% 92% 4%
4% 91% 5%
NA NA NA
NA NA NA
NA NA NA
NA NA NA
NA NA NA
NA NA NA
NA NA NA
NA NA NA
7% 44^, 48%
%Hg2 %MH?
0% 0%
94% 6%
NA NA
NA NA
94% 6%
92% 8«
93% 7%
96% 4%
95% 5%
95% 5%
95% 5%
79% 21%
NA NA
NA NA
NA NA
NA NA
NA NA
NA NA
NA NA
NA NA
98% 2%
SC Large Hospital HMlfHumid Sue 2 5 km i + RELMAPiEast 50th percennlei
Rural Home Gardener
mg'kg/dav
nhabnon
otal Ingestion
:ish Ingestion
\Vciier Ingestion
'roduce IngeMion
Grains
Legumes
Potaioes
Root vegetables
Fruits
Fruiting vegetables
Leafy vegetables
Animal Ingestion
Beef
Beef liver
Dairy
Pork
Poultry
Eggs
Lamb
Ingestion
Child
Total
1 6E-06
1 3E-05 05
O.OE+00 Oc:'t
0 OEtOO OCi
1 IE -05 909r
5 4E-06 4271
! 3E-06 10<7r
3 2E-07 2<«
1 8E-OS 0%
1 8E-06 14%
2 6E-06 20%
1 6E-08 0%
0 OE+00 OVc
O.OE+00 0%
0 OE+00 0%
0 OE-f-00 0%
O.OE+00 09f
0 OE+00 0%
0 OE+00 We
0 OE+00 0%
I 2E-06 10%
QRelmap % Background %ISC
4r( 9?% 3%
4% 8SC> 9%
NA N4 NA
NA NA NA
3% 92% 4%
3% 93% 4%
3% 91% 6%
1% 93% 6%
1% 93% 6%
4% 92% 4%
4% 92% 4%
4% 91% 5%
NA NA NA
NA NA NA
NA NA NA
NA NA NA
NA NA NA
NA NA NA
NA NA NA
NA NA NA
7% 44% 48%
%Hg2 %MHg
0% 0%
94 V, 6%
NA NA
NA NA
94% 6%
92% 8%
93% 7%
96% 4%
95% 5%
95% 5%
95% 5%
79% 21%
NA NA
NA NA
NA NA
NA NA
NA NA
NA NA
NA NA
NA NA
98% 2%
3-9
-------
Table 3-5
Predicted Mercury Exposure for Urban Average Scenario
ISC. Large Hospital HMKHumid Sue,
Urban Average
mg/kg/day
Inhalation
Ingestion Total
Soil Ingestion
ISC Large Hospital HMKHumid Site,
Urban Average
mg/kg/day
Inhalation
Total Ingestion
Soil Ingestion
2.5 km ) + RELMAP(East 50tl
Adult
Total
3.3E-07
2.0E-07 100%
2.0E-07 100%
2.5 km ) + RELMAPflEast 50tl
Child
Total
1 6E-06
1 6E-06 100%
1 6E-06 100%
i percentile)
%Relmap %Background %ISC
4% 93% 3%
6% 54% 40%
6% 54% 40%
i percentile)
%Relmap %Background %1SC
4% 93% 3%
6% 54% 40%
6% 54% 40%
%H«2 %MHg
0% 0%
98% 2%
98% 2%
%H?2 %MHg
0% 0%
98% 2%
98% 2%
Table 3-6
Predicted Mercury Exposure for Urban High-end Scenarios
ISC Large Hospital HMKHumid Site, 2 5 km ) + RELMAP(East 50th percentile)
Urban High End
mg/kg/da\
Inhalation
Ingestion Total
Fish Ingestion
Water Ingestion
Produce Ingestion
Grains
Legumes
Potatoes
Root \egetables
Fruits
Fruiting vegetables
Leafy vegetables
Soil Ineeslion
Adult
Total
4.9E-07
40E-06 100%
0 OE+00 0%
0 OE+00 0%
3 8E-06 95%
8 8E-07 22%
56E-07 14%
42E-08 1%
5 1E-09 0%
1 5E-06 39%
7 2E-07 1 8%
2 5E-08 1 %
2 OE-07 5%
%Relmap ^Background %ISC
4% 93% 3%
4% 91% 6%
N A NA NA
NA NA NA
3% 93% 4%
3% 949, 3%
3% 92% 5%
ITc 95% 4%
1% 95% 4%
49, 92% 4%
4% 92% 4%
4% 91% 5%
6% 54% 40%
%Hg2 %MHg
0% 0%
94% 6%
NA NA
NA NA
94% 6%
93% 7%
93% 7%
96% 4%
95% 5%
95% 5%
95% 5%
79% 21%
98% 2%
ISC Large Hospital HMKHumid Site. 2 5 km ) + RELMAPfEast 50th percentile)
Urban High End
mg/kg/day
Inhalation
Total Ingestion
Soil Ingestion
Child
Total
1 6E-06
6 IE-OS 100%
6 1E-05 100%
%Relmap %Background %ISC
4% 93% 3%
6% 54% 40%
6% 54% 40%
%Hg2 %MH?
0% 0%
98% 2%
98% 2%
3-10
-------
Table 3-7
Predicted Mercury Exposure for High-end Fish Consumption Scenario
ISC Large Hospital HMKHumid Site, 2 5 km ) + RELMAP(East 50th percentile)
Subsistence Fisher
mg/kg/day
Inhalation
Ingestion Total
Fish Ingestion
Water Ingestion
Produce Ingestion
Grains
Legumes
Potatoes
Root vegetables
Fruits
Fruiting vegetables
Leafy vegetables
Animal Ingestion
Beef
Beef liver
Dairy
Pork
Poultry
Eggs
Lamb
Soil Ingestion
Adult
Total
4.9E-07
1.1E-03 0%
1.1E-03 99%
l.OE-07 0%
9.7E-06 1%
2.7E-06 0%
7.6E-07 0%
2.0E-07 0%
1.2E-08 0%
4 6E-06 0%
1 4E-06 0%
5 5E-08 0%
0 OE+00 0%
0 OE+00 0%
O.OE+00 0%
0 OE+00 0%
0 OE+00 We
0 OE+00 0%
0 OE+00 09
0 OE+00 0%
1 5E-07 09
%Relmap %Background %ISC
4% 93% 3%
6% 34% 59%
6% 34% 60%
6% 32% 62%
4% 92% 4%
3% 93% 4%
3% 91% 6%
1% 93% 6%
1% 93% 6%
4% 92% 4%
4% 92% 4%
4% 91% 5%
NA NA NA
NA NA NA
NA NA NA
NA NA NA
NA NA NA
NA NA NA
NA NA NA
NA NA NA
79 449 489
%Hj>2 %MHe
0% 0*
1% 99*
0% 100%
87% 7*
94% 6%
92% 8%
93% 7%
96% 4%
95% 5%
95% 5*
95% 5*
79% 2!*
NA NA
NA NA
NA NA
NA NA
NA NA
NA NA
NA NA
NA NA
989 2%
ISC Large Hospital HMKHumid Sue, 2 5 km I + RELMAPiEast 50th percemilel
-ligh end Fish Consumer
mg/kg/da\
nhabnon
Total Ingestion
ribh Ingestion
Waier Ingestion
5roduce Ingestion
Grains
Legumes
Potatoes
Root vegetables
Fruits
Fruiting vegetables
Leafy vegetables
Soil Ingestion
Child
Total
1 6E-06
1 6E-03 09
1 5E-0? 999
2 2E-0'7 09
1 1E-05 19
5 4E-06 09
1 3E-06 09
3 2E-07 09
1 8E-08 0%
1 8E-06 0%
2 6E-06 0%
1 6E-08 0%
1 2E-06 0%
9Relmap 9 Background 9-iSC
49 93% 39
69 349 599
69 349 609
69 329 629
39 929 49
39 939 49
3% 919 6"7t
1% 939 69
1% 939 69
4% 929 4%
49 929 49
4% 91% 5%
79 44% 48%
9Hg2 %MHs
09- We
19 99%
09 10«WJ
879 7%
949 6<5
92% 8£
93% 79-
969 4«
95% 5S
95% 5S-
95% 5%
79% 21*
98% 2%
3-11
-------
Table 3-8
Predicted Mercury Exposure for Recreational Angler Scenario
ISC. Large Hospital HMKHumid Sue,
Recreational Angler
mg/kg/day
Inhalation
Ingestion Total
Fish Ingestion
Water Ingestion
Soil Ingestion
2.5 km ) + RELMAP(East 50tl
Adult
Total
49E-07
5.6E-04 0%
5.6E-04 100%
l.OE-07 0%
1.5E-07 0%
i percentile)
%Relmap %BackEround %ISC
4% 93% 3%
6% 34% 60%
6% 34% 60%
6% 32% 62%
7% 45% 48%
%He2 %MHe
0% 0%
0% 100%
0% 100%
87% 7%
98% 2%
3.2 Results of Combining Local and Regional Models - Predicted Human Exposure
In this section the results are presented for combining the local and regional impacts of
anthropogenic sources. For both the eastern and western sites, the 50th and 90th percentile of the
predicted air concentrations and deposition rates by the regional air model are used in conjunction with the
air concentrations and deposition rates predicted by the local scale model for each plant to obtain estimates
of environmental concentrations and possible exposure for humans. Background mercury concentrations in
environmental media are also included.
Tables 3-9 through 3-22 show the predicted human intake for each exposure scenario and site.
The results include receptors located at three distances from the facility (2.5km, 10km, and 25km). In all
cases, the predicted impact of the local source decreases as the distance from the local source increases.
3.2.1 Inhalation
Only for the chlor-alkali plant is the local source predicted to account for more than 50% of total
mercury exposure due to inhalation, and then only for the closest receptor considered (2.5km). The
primary form of mercury that constitutes this exposure is elemental mercury. Further, the inhalation route
is rarely predicted to be the dominant pathway of total mercury exposure when compared to indirect
exposure. The exception is the "urban average" exposure, in which an adult is assumed to ingest average
amounts of soil in the impacted area. The insignificance of exposure through the inhalation route when
compared to ingestion routes was described previously by the WHO (WHO, 1990).
3.2.2 Agricultural Scenarios
In general, the local source is predicted to account for less than 10% of the total mercury exposure
for the agricultural scenarios, compared to the contribution of the regional sources (RELMAP) and
background. This is because for these scenarios ingestion of plants is the dominant pathway for mercury
exposure, and the plant concentrations are predicted to accumulate mercury from the air more than via soil
uptake. The contribution of the local source is then roughly equivalent to the impact of the local source on
the air concentration. It is only for the chlor-alkali plant that this contribution is more than 20% (at 2.5km
and 10km). The mercury in potatoes and root vegetables results solely from root uptake since no air
uptake was assumed to occur for these plants (Appendix A). For leafy vegetables, all the mercury is
predicted to be from air uptake since no root uptake was assumed to occur. For grains, legumes, fruits and
3-12
-------
Table 3-9
Eastern Site RELMAP 50th and 90th Pcrccntiles
Predicted Ingestion (mg/kg/day) for Subsistence Farmer
Eastern Site
Rf-.LMAP 50th percenlilc
Variant h l.arge
Municipal Waste
Combuslor
Variant b Small
Municipal Waste
Combustor
l-arge Commercial HMI
l.arge Hospital HMI
Small Hnspilal HMI
Ijrge Hospital HMI
(wet scrubber)
Small Hospital HMI
(wet scrubber)
large Coal-fired Utility
Boiler
Medium Coal-fired
Utility Boiler
Small Coal-fired Utility
Boiler
Medium Oil-fired Utility
Bmli'r
Chlor-alknh plant
Predicted Ingeslion (mg/kg/dny) for SubsisU'nn- 1 .irnvr
2 Skin
Child Adult
Value %ISC Value '/ISC'
54E-05 9% -4 II. -05 ft%
5 OE-05 2% 1 91- 05 1 '/,-
5 OE-05 2% 19I-.-OS 1%
.5 3E-05 8% 411 .05 h'<.
4 9E-05 1 % 3 SI -OS 0%
49F.-05 0% 18K-05 (M
49R-OS (1% 1 UK-OS (1%
5 IR-05 4% (91 ,-05 1%
5 OR-05 2% "i ''1 05 1 '/
49I--05 1% ISI'05 (Y/r
49R-05 0% ^SI,-OS O'f.
1 .1K-04 62% 96I.-05 «)',(
10 km
Child Adult
V.ilue *ISC Value 9HSC
5 II- 05 4% 4 OR-05 4%
4 ">r 05 1 % 1 9H-05 1 %
4 91 05 0% 1 SR-05 0%
5 01 05 2V! ' 9I--05 1 %
491 05 0% 1Xl;-05 0%
4 9I-.-05 0% 1 KI-.-OS 0%
4 ')! -05 0% 1 8I-.-05 0%
501 05 1* ? 911-05 1%
491.1)5 1% 'XI-,-05 07n
4 91 05 07d 1 8R-05 07n
4 91 05 0% 1 8R-05 0%
ft M.-05 217n 49H-05 22%
25km
Child Adult
Value %ISC Value %ISC
5 OR-05 2% 39R-05 2%
49R-05 0% 3RR-05 0%
49R-05 0% 38E-05 0%
49R-05 1% .18R-05 0%
49R-05 0% 3.8E-05 0%
49R-05 0% 38R-05 0%
49R-05 0% 38R-05 0%
49E-05 0% 1.8R-05 0%
49E-05 0% .18E-05 0%
49E-05 0% 3.8E-05 0%
49E-05 0% .18E-05 0%
5 3E-OS 8% 4 2E-05 8%
3 13
-------
Table 3-9 (continued)
Eastern Site RKLMAP 50th and 90th Percentiles
Predicted Ingestion (mg/kg/day) for Subsistence Farmer
Eastern Sue
RI-.LMAP Wih pcrcennU
Variant h l.arge
Municipal Waste
Tombustor
Vananl b Small
Vlunicipnl Wasle
~ombustor
xirge Commercial HMI
1-arge Hospital HMI
Small Hospital HMI
Ijrge Hospital HMI
(wet scrubber)
Small Hospital HMI
wet scrubber)
.arge Coal-fired Ulilily
toiler
Medium Coal-fired
Utility Boiler
Small Coal-fired Utility
Boiler
Medium Oil-fired Utility
Boiler
Chlor-alkali plant
Predicted Inpcstion (mg/kg/day) for Subsistence 1 .irn»T
2 5km
Child Adult
Value %ISC Value »ISC
5 7E-OS K% 4 l| -05 ft'-f
5 3E-05 2% 4 1 E-05 1 7r
S IE-OS 2% 4 II -OS 1%
S 7E-OS R% 4 11 05
-------
Table 3-10
Eastern Site RELMAP SOth and 90th Percentiles
Predicted Ingestion (mg/kg/day) for Rural Home Gardner
liastern Site
RELMAP SOth perccnule
Variant h large
Miinicip.il W.iste
CornbuMor
Vananl b Smnll
Municipal Waste
Combustor
Urge Commercial HMI
Urge Hospital HMI
Small Hospital HMI
Ixirge Hospital HMI
!wel scrubber)
Small Hospital HMI
'wet scrubber)
Urge Coal-fired Utility
Boiler
Medium Coal-fired
Utility Boiler
Small Coal-fired Utility
Boiler
Medium Oil-fired Utility
Boiler
Chlor-alkali plant
Predicted Ingeshon (mg/kg/day) for Hui.il Honic ("ianlcncr
2 Skn)
Child Adull
Value %ISC Vjluc %ISC
1 IK-OS 87c ') 91. 06 sv,.
1 2K-OS 7% 9 SI', 06 1%
1 2K-05 2% 9 SI. -06 I'.i
1 IE-OS 9% 99I-.-06 S%
1 2E-OS 1* 94K-06 ()'«
1 2E-OS 0% <) 41 -06 <>!
1 21-,-OS 0% ';j|,-()6 ()(
1 2E-OS 1% ') S|- Oft 1 %
1 2E-OS 2% 0 S|'-06 I'/r
1 2E.-OS 1 % 9 4MXS O'/f
1 2F.-OS 0% 9 4I-.-06 0V,.
1 OI-.-OS 62% 2 21',-OS SS%
10 km
ClnM Adull
Value '»ISC Value V,ISC
1 ">! (IS -1", 9 7I.-06 '%
1 _>l (IS |% 94E-06 1%
1 ?! OS 0% 94f'-O6 0%
1 ">! -OS ?'/,. 9 SI-,-06 1%
i :i os (M <) 41-.-06 0%
1 .'1 OS (Yi 94F.06 0%
1 :i OS ()'/,. 94I.-06 0%
1 ?l OS 17,, 94K-06 0%
1 21, -OS I'/,. 94K-06 0%
1 :>' OS O'/! 94C-06 0%
1 21 OS 0% 94E-06 0%
1 sr.-OS 22% 1 2E.-05 20%
2Skm
Child Adull
Value %1SC Value %ISC
1 2E-05 2% 95E-06 1%
I 2E-05 0% 94E-06 0%
1 2E-OS 0% 9 4E-06 0%
1 2E-OS 1% 94E-06 0%
1 2E-05 0% 9 4E-06 0%
1 2E-05 0% 94E-06 0%
1 2K-OS 0% 9 4E-06 0%
1 2E-OS 0% 9 4E-06 0%
1 2E-05 0% 9 4E-06 0%
1 2E-05 0% 9 4E-06 0%
1 2E-OS 0% 9 4E-06 0%
1 3E-05 8% I.OE-05 7%
3-15
-------
Table 3-10 (continued)
Eastern Site RELMAP 50th and 90th Perccntiles
Predicted Ingest ion (mg/kg/day) for Rural Home Gardner
Eastern Silc
RELMAP 90th percentile
Variant h Ixtrge
Municipal Waste
Combustor
Vananl b .Small
Municipal Waste
Comhuslor
1 -arge Commercial HMI
Urge Hospital HMI
Small Hospital HMI
Urge Hospital HMI
!wet scrubber)
Small Hospital HMI
(wet scrubber)
Large Coal-fired Utility
Boiler
Medium Coal-fired
Utility Boiler
Small Coal-fired Utility
Boiler
Medium Oil-fired Utility
Boiler
C'hlor alkali plant
Predicted Ingestion (mg/kg/diiy) for Rural Home (i.mlcner
2 5km
Child Aduli
Value %ISC Value 'USC
1 .IK-OS 8% 1 or -OS v/,
1 2E-OS 2% 981-06 \1
1 2E-OS 2% ') KI-.-06 1 %
1 1E-05 8% 1 Of- OS S%
1 2E-OS \% 9KI-.-06 O'/f
1 2E-OS 0% ') HI, 06 0*
1 2E-OS 0% 971. 06 m
\ JE-OS .1% 9Ki',-(>6 r?
1 2E-OS 2% <)XI,-06 |%
1 2E-05 0% 0 XI -On (}'t-
I.2E-OS 0% 071. -06 0*
1 IE-05 60% 2 H -OS w,f
10 km
Child Adult
V.iluc %ISC Value »ISC
1 11, -OS 4% 1 Oi;-O.S 1%
121 -OS 1% 9RI.-06 \%
\ l\ -OS o* 9 8E-06 0%
1 21 OS 2'>r 9SH-06 1%
1 21 -OS 0% 9 7K-06 0%
1 21 OS 0% <) 7C-06 0*
1 21 OS 0% <) 7li-06 0%
1 21 -OS \'t- 98I:-06 0%
1 21 os i% ixi -of, n%
\ 21 OS ()/ 9 7I--06 ()'(
1 21 OS (Ylr 9 7H-06 0%
1 ftl;-OS 21% 1 2E-O.S 20%
25km
Child Adult
Value %ISC Value %ISC
1 2E-OS 2% 99E-06 1%
1 2E-05 0% 9 8E-06 0%
1 2t-05 0% 9 7E-06 0%
1 2E-05 1% 98E-06 0%
1 2E-05 0% 9 7E-06 0%
1 2E-05 0% 9 7E-06 0%
1 2E-05 0% 9 7E-06 0%
1 2E-05 0% 9 7E-06 0%
1 2E-OS 0% 9 7E-06 0%
1 2E-05 0% 9 7E-06 0%
1 2E-05 0% 9 7E-06 0%
1 .IE-OS 7* I.OE-OS 7%
-------
Table 3-11
Eastern Site RELMAP 50th and 90th Pcrcentiles
Predicted Ingcstion (mg/kg/day) for Urban Average
Eastern Site
RFJ.MAI* SOth perccntile
Variant h.ljrpc
Municipal Waste
Combustor
Variant b Small
Municipal Waste
Comhiistor
Ijrgc Commercial
HMI
large Hospital HMI
Small Hospital HMI
ljuff Hospital HMI
(wet scrubber)
Small Hospital HMI
'wet scrubber)
l-arge Coal-fired
Utility Boiler
Medium Coal-fired
Utility Boiler
Small Coal-fired
Utility Boiler
Medium Oil-fired
Utility Boiler
Chlor-alkali plant
Predicted Ingeslion (mg/kp/day) tor Urb.in Averse
25km
Child Adult
Value %1SC V.iluc %ISC
1 6E-06 W% 1 9H-07 W:
1 IE-06 10% 1 11 -07 10'*
1 IE-06 9% 1 11 -07 ')'/,.
1 6F.-06 40% 2 Ol; 07 40'/,.
I.OE-06 4* 1 11,07 4%
1 OK-06 2% 1 2h-07 I'l,
9 9E-07 0% 1 21 -07 O'/,
1 .lfi-06 26* 1 hi -07 21,'','
1 IE-06 IW 1 4I.-07 11*
1 OI;.-()6 3* 1 21-.-07 "(%
\ OE-06 0% 1 21. -07 ()'<-
6 IP.-06 84% 74I-.-07 S4%
10 km
Child Adult
V.iluc %ISC Value %ISC
1 :i -06 20'< 1 51 .-07 20*
1 01 Ofi 17r I 2U-07 17n
1 01 Of, 2% 1 21 -07 2%
Ml Of, I0'< 1 H.-07 W7o
1 0(- (If, I'/ 1 2R-07 1%
1 01 -Of, 0% 1 2P.-07 0%
') ')! -07 0% 1 2K-07 0%
1 II Of, h% 1 11- -07 fi%
1 (»l -Oft 4% 1 M--07 4%
1 01- Of, 1% 1 2K-07 1%
9 <)l -07 0% 1 21-.-07 0%
1 7l-,()f, 41% 20P.-07 41%
2.5km
Child Adult
Value %ISC Value %ISC
1 IE-06 8* 1 3E-07 8%
1 OE-06 1% 1 2E-07 1%
1 OE-06 0% 1 2E-07 0%
1 OE-06 3% I.2P.-07 3%
9 9E-07 0% 1 2E-07 0%
9 9E-07 0% 1 2E-07 0%
9 9E-07 0% 1 2E-07 0%
1 OK-06 2% 1 2E-07 2%
1 OE-06 2% 1 2E-07 2%
1 OE-06 0% 1 2E-07 0%
9 9E-07 0% 1 2E-07 0%
1 2E-06 15% 1 4E-07 15%
3-17
-------
Table 3-11 (continued)
Eastern Site RELMAP 50th and 90th Percentiles
Predicted Ingestion (mg/kg/day) for Urban Average
Eastern Site
RRLMAP Wth percenlilc
Vanani h Urge
Municipal Waste
"omhustor
Vanani h Small
vlumcipal Waste
Combustor
Large Commercial
HMI
Urge Hospital HMI
Small Hospital HMI
Urge Hospital HMI
wet scrubber)
Small Hospital HMI
(wet scrubber)
Urge Coal-fired
Ulilily Boiler
Medium Coal-fired
Utility Boiler
Small Coal-fired
Utility Boiler
Medium Oil-fired
Utility Boiler
Chlor-nlk.ili pl.ml
Predicted Ingeslion (mg/kg/day) for Urban Average
2Skm
Child Adult
Value %ISC Value
-------
Table 3-12
Eastern Site RKLMAP 50th and 90th Percentiles
Predicted Ingestion (mg/kg/day) Tor Urban High End
Kastcrn Sue
REl.MAP50thpcrcenlile
Variant b Ijrge
Municipal Waste
Comhustor
Variant h Small
Municipal Waste
Combustor
Large Commercial
HMI
Large Hospital HMI
Small Hospital HMI
l-argc Hospital HMI
(wet scrubber)
Small Hospital HMI
(wet scrubber)
l-irge Coal-fired
Utility Boiler
Medium Coal-fired
Utility Boiler
Small Coal-fired
Utility Boiler
Medium Oil-fired
Utility Boiler
Chlor-alkali plant
Predicted Ingestion (mg/kg/day) lor Urban High l:,iul
25km
Child Adull
Value %1SC Value r/ISC
5 9I-.-05 ix% t 06 6'/
.1 8F.-05 4% 3 ?! 06 (W
.1 7R-OS 2% 1 711-06 (I'/r-
37H-05 0% 17I-. 06 W'r
40E-05 26* 1KI-W) 2'/'
4 2U-05 H* lSI>Wi 1%
.1 8H-05 1% ^ 7I-.-06 ()'/,
1 7E-OS 0* 1 71 -06 0'*
2 3F.-04 84* S 91 -06 W/,
10 km
Child Adult
Value OHSC Value %ISC
4 61 OS 20% 1 9l;-0ft V/r
1 XI 05 1% 1 7I--06 1*
1 71 -05 2% .1 7H-06 07r
4llv()5 |{)'* 18E-06 1*
1 71' 05 I* 17E-06 0%
1 71 -05 0* 1 7E-06 0*
1 71 05 0% 3 7E-06 0*
1 ')! 05 6% 1 71 .-06 0*
1SI--05 4'* 17E-06 0%
171, -05 1% 17E-06 0%
1 71 -05 o* 1 7E-06 0%
6 2I;-05 41% 47P-06 20%
25km
Child Adull
Value *ISC Value %ISC
40E-05 8* 38E-06 2%
37E-05 1% 37E-06 0%
.17E-05 0* .17E-06 0*
38E-05 3% 37E-06 0%
.1 7E-05 0% .1 7E-06 0%
37E-0.5 0% 37E-06 0%
3 7E-05 0% 1 7E-06 0%
3 8E-05 2* 3 7E-06 0%
37E-05 2% 37E-06 0%
3 7F.-05 0% 3.7E-06 0*
37E-0.5 0% 3.7E-06 0%
43E-05 15% 4.0E-06 7%
3-19
-------
Table 3-12 (continued)
Eastern Site RKLMAP 50th and 90th Perccntiles
Predicted Ingcstion (mg/kg/day) for Urban High End
Eastern Sue
RE1.MAP 90th pcix-cntilr
Variant b l.arge
Vfunicip.il Waste
~ombusior
Vanant h Small
Municipal Waste
L'ombuslor
!*arge Commercial
HMI
Large Hospital HMI
Small Hospital HMI
Urge Hospital HMI
(wet scrubber)
Small Hospital HMI
[wet scrubber)
l-arge Coal-fired
Utility Boiler
Medium Coal-fired
Utility Boiler
Small Coal-fired
Utility Boiler
Medium Oil-fired
Utility Boiler
Chlor alkali plant
Predicted lnge<(ton (ing/kg/d;iy) for Urh.in Hipb I'.ml
2 Skm
Child Adull
Value %1SC Value '*ISC
7 OE-OS 33% 4 1 1 -06 S'/f.
S IE-OS 8% 19f,-06 I'-f
5 1 E-OS 7% 1 9E-06 1 '/.
7 IE-OS 34% 4 lf-,-06 67r
49E-OS 3% I'll- -Oft flri
4 RE-OS 1% 10I.-06 0%
47E-OS 0% V)|.-06 ()%
60E-OS 21% 1')|--0fi 2%
S IE-OS 11% 191 06 1%
4 81 -OS 1% <9I,-06 0%
47E.-OS 0% 39I.-06 0'(
24I-..04 80% 9II-.-06 W*
10 km
I'hild Adult
Value %ISC Value %ISC
Sftl.-OS 16* 4 01 .-06 1%
4X1,05 1% 19B-06 1%
4«I-OS 1% 19E-06 0%
S II OS 8% 3 91. -06 !*
4 71 OS 0% 1 91-06 0%
4 71-, OS 0% 1 9I.-06 0%
4 71- OS 0% 1 9E-06 0%
4')|,-(IS S% .'9E-06 0%
4 '»! -OS V/f. 3 9I-.-06 0%
4 SI -OS 1 % 1 91.-06 0%
4 71 -OS 07r 1 9I--06 0%
7
-------
Table 3-13
Eastern Site RKLIMAP 50th and 90th Perccntiles
Predicted Fngestion (mg/kg/day) for Subsistence Fisher
liaslcrn Sue
RFI.MAP 50ih pcrcenllle
Variant h I,argc
Municipal Waste
Combustor
Variant h Small
Municipal Waste
Comhustor
^irge Commercial
HMI
jirge Hospital HMI
Small Hospital HMI
1-arge Hospital HMI
wet scrubber)
Small Hospital HMI
wet scrubber)
.arge Coal- fired
Utility Boiler
Medium Coal- fired
Utility Boiler
Small Coal fired
Utility Boiler
Medium Oil-fired
Utility Boiler
Chlor alkali plant
Predicted Ingeslmn (mg/kg/day) tor Subsistence Cipher
21km
Child Aduli
Value %ISC Value '/f|SC
1 4I-.-01 V4% 1 (II (H VI',!
77h-(M 18% 56I--04 W/,
78E-04 19% ^ 11 -(14 10%
1 6K-01 59% 1 II-, 01 «'/,.
69P.-04 9% 5 IC-04 <}'/;
66F.-04 47-- 4«l.04 VI,
6 3E-04 0% 4 61 04 0%
1 IE-01 42% 791-04 42r',
82F.-04 2.'% 60104 2V(.
6 7P.-04 6* 4 91 04 6'/r
64F.-04 1% 4 61- -04 1%
80E-0.1 92% S')l.-01 927n
10 km
Child Adult
V.iluc 7HSC Value %ISC
9 ()!. (14 W«. 66I.-04 Vt%
(> 71 -04 6% 4 911-04 6%
6 SI, .04 17, 47P.-04 W
7 61 -IM 1 7',{- 04 0%
1 4P.-01 5ft% 1 Oli-01 56%
25km
Child Adult
Value %ISC Value %ISC
72K-04 M% 5.1E-04 1.1%
64E-04 2% 47E-04 2%
6JE-04 1% 46E-04 1%
66E-04 4% 48E-04 4%
63E-04 0% 46E-04 0%
63E-04 0% 46E-04 0%
63E-04 0% 46E-04 0%
65E-04 4% 48E-04 4%
65E-04 3% 47E-04 3%
6.1E-04 1% 4.6E-04 1%
63E-04 0* 46E-04 0%
82E-04 23% 5.9E-04 23%
3-21
-------
Table 3-13 (continued)
Eastern Site RELMAP 50th and 90th Percentiles
Predicted Ingcstion (mg/kg/day) for Subsistence Fisher
P-astern Sue
RELMAP 90th percenlile
Varianl h Large
Municipal Waste
Combuslor
Variant b Small
Municipal Waste
Combuslor
l.arge Commercial
HMI
Urge Hospital HMI
Small Hospital HMI
1-arge Hospital HMI
(wet scrubber)
Small Hospital HMI
(wet scrubber)
1-arge Coal-fired
Utility Fioiler
Medium Coal-fired
Utility Boiler
Small Coal-fired
Utility Boiler
Medium Oll-fircd
Utility Boiler
Chlor-alkali planl
Predicted digestion (mg/kg/day) lor Subsidence 1-isher
2 Urn
Child Adult
Vnlue %ISC Value %ISC
1 6E-0.1 45% 1 2K-01 4V/,.
1 IF.-0.1 H* 77I:-04 11%
1 1F.-03 14% 77H-04 14%
1 8E-01 50% 1 1I.-01 50%
97F.-04 6% 7 IT-04 6%
9 4H-04 3% ft HI 04 V*
9IP.-04 0% ft 71- 04 0%
1 4K-01 33% 1 (H',-0! U%
1 IF.-03 17% 8 01- -04 17%
95li-04 4% 70I-.-04 4%
92P.-04 1% 671 (M 1%
83F.-01 89% 6 IF.-03 89%
10 km
C'biUI Adult
Value %ISC Value *ISC
1 2F-0' 2?% 86I--04 21%
9 SI -04 M 6 9I-.-04 4%
') M.-04 2% 68F.-04 2%
101-01 11% 76F.-04 11%
') ?l ()4 I'/, 67F-:-<>4 1%
') 1 1 -04 0% 6 7F.-04 0%
9 1 1 -04 O'/f 6 6I--04 0%
<;«i;-(M !'/< 7211-04 7%
9 51. -04 5% 70F.-04 5%
9 11. -04 2% 67I-.-04 2%
') 11-04 0% 67F.-04 0%
1 71 -01 47% 1 1F.-0.1 47%
25km
Child Adult
Value %ISC Value %ISC
1 OF 01 9% 7 3E-04 9%
92B-04 1% 67E-04 1%
9IE-04 0% 67E-04 0%
94E-04 3% 69E-04 3%
9IE-04 0% 67F.-04 0%
9 IE-04 0% 66E-04 0%
9.IE-04 0% 66E-04 0%
9 IE-04 3* 6 8E-04 3%
9..1E-04 2% 68E-04 2%
9 IE-04 1% 67E-04 1%
9 IE-04 0% 66E-04 0%
1 IE-03 17% 8.0E-04 17%
3-22
-------
Table 3-14
Eastern Site RKLMAP 50th and 90th Percentiles
Predicted Ingcstion (mg/kg/day) for Recreational Angler
faMcrn Site
RHLMAP 50th pcrcemilc
Predicted Ingeslion (mp/kg/d,iy) for Recreational Angla
2 Skin
Child Adult
Value %ISC Value '/ISC
Vnrianl h Ixirgo Municipal Wasle Cnmhus'nr 5 01 -114 54'f
Vannnl h Small Municipal Waste Combuslor 2 SI 04 IS'<
large Commercial HMI 2 SI.-04 \')"r
Large HospKal HMI 5 M;-04 60%
Small Hospital HMI 2 S| -04 9%
Urge Hospital HMI (wet scrubber) 2 4I-.-04 4'*
Small Hospital HMI (wet scrubber) 2 M-.-04 ()'/,
Urge Coal-fired Utility Boiler 3 ')! -04 42'/!
Medium Coal-fired Utility Boiler 3 OI.-04 2J'f
Small Coal-fired Utility Boiler 2 41 -04 (,'/,
Medium Oil-fired Utility Boiler 2 M -04 1 '/,
Chlor-alkali plant
2')l.-0.1 ')27r
10 km
Child Adult
Value '/frISC Value %ISC
1 1F,-(M W«.
2 4I-.-04 ft%
2 M.-04 _!%
2 8P.-04 IS7o
2.1U-04 1%
2 1I--04 1%
2 1F.-O4 07n
2SI:.-04 10%
2 4I.-04 7%
2 31 -04 2%
2 M-.-04 0%
S 2Fi-04 S6%
25km
Child Adult
Value %ISC Value tttSC
2 6E-04 1 3%
2 3E-04 2%
2 3E-04 1 %
2 4E-04 5%
2 -1E-04 0%
2.3E-04 0%
2.3E-04 0%
2 4E-04 4%
2 3E-04 3%
23E-04 1%
2 3E-04 0%
2 9E-04 23%
Bastern Site
Rlil-MAP Wlh pcrcemilc
FVedicted Ingestion (mg/kg/day) lor Recreational Anplcr
2 5km
Child Adult
Value *ISC Value %ISC
Variant h Large Municipal Waste Comhusfnr 6 01, -04 4S'^.
Variant b Small Municipal Wasle Combuslor 1 XI 04 1 >%
Ijirge Commercial HMI 1 Kh -04 14".
Ijrge Hnspilal HMI 671-04 MV,
Small Hospital HMI 3 ">l,-04 7'/,.
1 .arge Hospital HMI (wet scrubber) 1 4I.-04 \%
Small Hospital HMI (wet scrubber) 1 M>04 0*
Urge Coal-fired Utility Boiler 4 <)\~. M IV;
Medium Coal-fired Ulilily Boiler 40I-O4 IS'f.
Small Coal-fired Utility Boiler 1 4I-.-O4 W
Medium Oll-fircd Utility Boiler 1
33P.-04 2%
\ 3P.-04 0*
6,2P.-04 47%
25km
Child Adult
Value %ISC Value %ISC
.3 6E-04 9%
3 3E-04 1 %
3 3E-04 0%
3 4E-04 3%
3 3E-04 0%
3 3E-04 0%
3 3E-04 0%
3 4E-04 3*
3 4E-04 2%
J3E-04 \%
J3E*4 0%
40E-04 17%
3-23
-------
Table 3-15
Western Site RELMAP 50th and 90th Percentiles
Predicted Ingestion (mg/kg/day) for Subsistence Farmer
Weslcrn Sue
REI.MAP 50th pcrcenlile
Variant h 1 -nrff
Municipal Wasie
~ombuslnr
Vananl b Small
Municipal Watte
Combuslor
Large Commercial HMI
Urge Hospital HMI
Small Hospital HMI
Large Hospital HMI
(wet scrubber)
Small Hospital HMI
wet scrubber)
Large Coal-fired Utility
Boiler
Medium Coal-fired
Utility Boiler
Small Coal-fired Utility
Boiler
Medium Oil-fired Utility
toiler
Chlor-alkali plant
Predicted Ingestmn (mg/kp/d.iy) for Subsistence Kinner
25km
Child Aduh
Value %ISC Vjluc '/,ISC
4 611-05 8% t 61-. 05 6'<
4311-05 1% \ S| .-05 |*
4.1E-05 2% 15E-05 1%
46E-05 8% 1nE05 5%
4 JE-05 1 % 1 5E 05 0%
4.1E-05 0% 14E-05 07,
4.1E-05 0% 141 ,05 (}%
44H-05 1% 1 5C-05 i*
4.1E-05 1% 15C05 |V,
4 1E-05 0% 1 41 -05 (}'/,
4 3E-05 0% 1 41 -05 ()«
1 IE-04 61% 8 M.-05 58'/r
10 km
Child Adull
Value *ISC Value *ISC
) -II 05 4% 1 5K-05 1%
1 M -05 1% 1 5E-05 0%
4 11 05 0% .1 4E-0.5 0%
4 M.-05 1% 1 .5E-0.5 1%
4 11, 05 0% 1 4E-05 0%
4 ?l -05 0% A 4E-0.5 0%
4 11. 05 0% 1 4E-05 0%
4 1| 05 |% 1 5E-0.5 0%
411-05 |% 1 5I--05 0%
4 11 05 0% 1 4E-05 0%
4 ir, 05 0% 1 4P.-05 0%
5 21 .-05 19% 42E-05 17%
25km
Child Adull
Value %ISC Value %ISC
41E-05 2% .15E-0.5 1%
4 1E-05 0% 3 4E-05 0%
4.1E-05 0% 3.4E-05 0%
43E-05 0% 3.4E-05 0%
43E-05 0% 34E-05 0%
4.3E-05 0% 34E-05 0%
4 3E-05 0% 3.4E-OJ 0%
4.1E-05 0% 34E-OS 0%
43E-05 0% 34E-05 0%
43E-05 0% 34E-05 0%
4 1E-05 0% .1 4E-05 0%
4.6E-05 7% 3.7E-05 6%
-------
Table 3-15 (continued)
Western Site RKLMAP 50th and 90th Percentiles
Predicted Ingest ion (mg/kg/day) for Subsistence Farmer
Western Site
RULMAI'Wlh pcrcenlile
Variant h Urge
Municipal Waste
Comhustor
Variant h Small
Municipal Waste
Combuslor
Urge Commercial HMI
Urge Hospital HMI
Small Hospital HMI
Urge Hospital HMI
(wcl scrubber)
Small Hospital HMI
(wel scrubber)
Large Coal-fired Utility
Boiler
Medium Coal-fired
Utility Boiler
Small Coal-fired Utility
Boiler
Medium Oll-firrd Utility
Boiler
Chlor-allcali plant
Predicted Ingcstion (mp/kp/ilay) for SubMslcncc 1 arnicr
2 1km
Child Adult
Value %ISC Value '/MSC
4 <)i:-05 1% i xi- os s%
46E-05 2% 16I-. OS 1%
46E-OS 2% 16I-.-OS |%
4 9E-05 7% 1 XI--OS Vj.
4 SE-05 1% Ifih-OS (1%
4 SE-OS 0% 161, -OS 07r
4 SK-05 0% 1 61 ,-OS 07,
46F.-O.S 1% 16I:-OS 2'i.
46E-OS 1% 161 -OS }/,.
4 SE-OS 0% 1 6I--OS 0%
45E-O.S 0% 16P-OS 0V,
1 IE-04 60% K4I--OS S7%
10 km
Child Adult
V.iluo %1SC Value %ISC
4 71 OS 4'* 1 7I--OS 1%
|S|,OS 1% 16K-OS 0%
4 SI- -OS m- 16E-05 0%
4 61 -OS 1* 16F.-OS |%
4 SI -OS 0% .1 6I--OS 0%
4 si -os 0% 1 6r-os- 0%
4 M -OS 0% 1 6H-OS 0%
461, -OS I7r. 161- -OS 0%
4 SI-.-OS 1 % 1 fill-OS 0%
4 SI--OS 0% 1 6E-OS 0%
4 SI, -OS 0% 16P.-OS 0%
SSI ,-OS 18% 4 IE-OS 17%
25km
Child Adult
Value %1SC Value %ISC
46E-05 2% 36E-05 1%
4 SE-05 0% .16E-05 0%
45E-05 0% 36E-05 0%
4.5E-05 0% 3.6E-05 0%
45E-05 0% 36E-05 0%
45E-05 0% 3.6E-OS 0%
4 SE-05 0% .1.6E-05 0%
4 SE-OS 0% 36E-05 0%
45E-05 0% .16E-05 0%
45E-05 0% .16E-05 0%
4 5E-05 0% .1 6E-05 0%
48E-05 6% 38E-05 6%
3-25
-------
Table 3-16
Western Site RELMAP 50th and 90th Percentiles
Predicted Ingcstion (mg/kg/day) for Rural Home Gardner
Western Sue
RF.LMAP 50th pcrccnlile
Variant b Ijirge
Municipal Waste
rombusior
Variant b Small
Municipal Waste
Tombustor
Large Commercial HMI
Large Hospital HMI
Small Hospital HMI
Large Hospital HMI
wet scrubber)
Small Hospital HMI
(wet scrubber)
[jrgc Coal-fired Utility
Boiler
Medium Coal-fired
Utility Boiler
Small Coal-fired Utility
Boiler
Medium Oil-fired Utility
Boiler
Chlor-alkali plant
Predicted Ingrttion (mg/kg/day) for Rural Honic Ci.irdrnrr
2 Skin
Child Adull
Value %ISC Value '-(ISC
99I-.-06 1% H4L-06 VI,
9 3P.-06 2% 8 2I--06 1%
9 IE-06 2% 82I--06 1%
1 OE-05 8% 8 SP -06 4%
9 2E-06 1% 8 Il.-Oft <)'/,.
92E-06 0% 8 in-06 0%
92E-06 0% 8 II" -06 n'/(
9.1E-06 \% K II. -06 ()%
9 2E-06 1 % 8 1 1", (Mi ()'/!
92R-06 0% R ir-06 0%
92E-06 0% 8 ||, -06 (1%
2 5F.-(n 61% 1 9P.-0'i S7'*
10 km
Child Adult
V.iluc 'AISC Value %ISC
') M-.-flf) 4% 8 1H-06 2%
921 06 1% 8II.-06 0%
021.06 0% 8IE-06 0%
-------
Table 3-16 (continued)
Western Site RELMAP 50th and 90th Percentiles
Predicted Ingestion (ing/kg/day) for Rural Home Gardner
Western Site
RELMAI' 9<)th percentile
Variant h 1 .argc
Municipal Waste
Combuslor
Variant b Small
Municipal Waste
Combuslor
Ijirge Commercial HMI
Large Hospital HMI
Small Hospit.il HMI
I jrpc Hospital HMI
(wet scrubber)
Small Hospital HMI
'wet scrubber)
1 -arge Coal-fired Utility
Boiler
Medium Coal-fired
Utility Boiler
Small Coal-fired Utility
Boiler
Medium Oil-fired Utility
Boiler
Chlor-alkali plant
Predicted Ingestion (mg/kg/day) for Rur.il Home (i-mlener
2Skm
Child Adult
Value %\SC Value '/,ISC
1 OF-OS 7% X ftl -06 V,
96P.-06 2% X4I--06 1%
96E-06 2% 8 41 ,-06 1%
1 OE-05 8% S Mi-06 4',«
95E-06 1% XII, 06 0%
95E-06 0% S 11, -06 ()'/!
95R-06 0% X Il.-On 0%
96H-06 \% 8 ll:,-(Xi ()'/,
9SK-06 1* 8 lh-06 0%
9 SF,-()6 0% « 11. -Oft 0%
9 SE-06 0% X 11, -05 0%
2 SE-05 ft27o 1 OI--OS ^7%
10 km
C'lulcl Adult
Value %ISC Value %ISC
') XI Oft 4% 8 'il'-Oft 2'/r
'1 V Oft 1 % 8 1K-06 0%
'JSI.-Oft 0% 8 1P.-06 0%
9 61 -Oft 2% SIH-Oo 1%
') SI (K) 0% 8 Ui-Ofi 0%
') M Oft 0% 8 Ip.-Oft 0%
I S| .(Ki O'/r 8 M'-Oft 0%
') SI. -Oft 07<. X 11 -06 0%
')SI Of, 17^ 8 11 06 0%
') SI -Oft 0% 8 1F.-06 0*
<> sr or, o* « ii;-o6 o%
1 21-. OS 19% 99I--06 17%
25km
Child Adult
Value %ISC Value %ISC
96E-06 2% 84E-06 1%
9 5E-06 0% 8 .1E-06 0%
95E-06 0% 83E-06 0%
9 SE-06 0% 83E-06 0%
9 SE-06 0% 8 .1E-06 0%
9 SE-06 0% 8.1E-06 0%
95E-06 0% 83E-06 0%
95E-06 0% 8.1E-06 0%
9 5E-06 0% 8 1E-06 0%
95E-06 0% 83E-06 0%
95E-06 0% 8SE-06 0%
1 OE-OS 7% 8 8E-06 6%
3-27
-------
Table 3-17
Western Site RELMAP 50th and 90th Percentiles
Predicted Ingest ion (me/kg/day) for Urban Average
Western Site
RELMAP 5arge
Municipal Waste
~ombmtor
Vananl b Small
Municipal Waste
^omhustor
Jirge Commercial HMI
Large Hospital HMI
Small Hospital HMI
Large Hospital HMI
wet scrubber)
Small Hospital HMI
wet scrubber)
Large Coal-fired Utility
Boiler
Medium Coal-fired
Utility Boiler
Small Coal-fired Utility
toiler
Medium Oil-fired Utility
Boiler
Chlor alkali plant
Predicted Ingestion (mg/kp/day) for Urban Average
25km
Child Adult
Value %ISC Value %ISC
49U-07 75% 60I-.-OX 7V/
2 OF.-07 39% 2 5I'-08 V)*
2 OE-07 38% 2 4I: OX IS'/,
6 2E-07 80% 7 M--OX 80%
I6F.-07 21% 1 91, -OS 21*
1 4E-07 10% 1 7F-OX in*
1 2P.-07 1% 1 51 -OX I'f
20K-07 37% 24I--OX 17%
1 6K-07 25% 2 01 .08 ?V«
1 4V.-Q1 15% 1 XI 08 |Sr{
1 3E-07 2* 1 M-..08 Tt
40E-06 97% 4')r,-07 97%
10 km
C'luld Adult
Value %ISC Value %ISC
111.07 60% 17P.-08 60%
1 SC.-07 15% I SE-08 15%
1 \\. 07 7% 1 6H-08 7%.
20T.-07 18% 24U-08 38%
1 11; 07 1% I 5I;-08 3%
1 21 07 1% 1 511-08 1%
1 ?1 07 0% | 5I-.-08 0%
1 S| -(17 16% 1 XI-.-08 16%
1 5|- 07 19% 1 8F.-08 19%-
1 3I-.-07 7% 1 6E-08 7*
1 .'1 O7 IV 1 -ili-OS 1%
5 f\ -07 79% 7 OF:,-08 79%
25km
Child Adult
Value %ISC Value %ISC
1 9E-07 35% 2 3E-08 35%
1 3E-07 5% 1 6E-08 5%
1 3E-07 2% 1 5E-08 2%
I.4E-07 13% 1 7E-08 13%
1 2E-07 1% I.5E-08 1%
1 2E-07 0% 1 5E-08 0%
1 2F.-07 0% 1 5E-08 0%
1 4F.-07 14% 1 7E-08 14%
1 4E-07 13% 1 7E-08 13%
1 3E-07 3% 1 5E-08 3%
1 2H-07 0% 1 5E-08 0%
24E-07 49% 29E-08 49%
1.98
-------
Table 3-17 (continued)
Western Site RELM A P 50th and 90th Perccntiles
Predicted Ingestion (nig/kg/day) for Urban Average
Western Site
RfcLMAP 90(h percentile
Vanani h 1-arge
Municipal Waste
Combuslor
Variant b Small
Municipal Waste
Combuslor
large Commercial HMI
Ijirgc Hospital HMI
Small Hospital HMI
Large Hospital HMI
(wet scrubber)
Small Hospital HMI
!wet scrubber)
Urge Coal-fired Utility
Roller
Medium Coal-fired
Utility Boiler
Small Coal-fired Utility
Boiler
Medium Oll-fircd Utility
Boiler
Chlor-alkali plant
Predicted Ingcslion (mg/kg/day) for Urban Average
2 Skin
Child Adult
Value %ISC Value 7,-ISC
6IE-07 61* 741-OX 6 1'/,,
3 2E-07 2">% 1 9I---08 21%
3 2E-07 24% 1 8F.-08 24%
74E-07 67% R9E-OR (,7V,.
27E-07 12* 31K-OR I2'/
2 5E-07 6% 1 1 K-08 6%
2 4E-07 091' 2 9I-.-08 07,
1111-07 23* 1RP-08 2(7,
28I--07 15% 14I>(I8 |S7r
2 6E-07 8* 1 2U-OX 8%
24E-07 1* 29i;.()8 1%
4IE-06 94% SOI--07 94%
in km
ChiM Adult
Value 7,-ISC Value %ISC
4 2r,-07 447« 1 21-08 44%
2 (,l:-07 9% 1 2i:-08 9%
2 Sl;-07 4% 3 OE-08 4%
1 1 1--07 247o 1 811-08 24*
2 41" (17 2% ' OF; 08 2%
24I-.07 1% 29I-.-08 1*
241,07 0% 29U-08 0*
2 (,1.07 <)% 32E -08 9*
27I-.-07 10% 3 2E-08 10*
2 Sr-07 4* 3 OE-08 4%
24I-.-07 1* 29E-08 1%
7 Or.-07 667^ 8
-------
Table 3-IS
Western Site RELM AP 50th and 90th Percentiles
Predicted Ingcstion (mg/kg/day) for Urban High End
Western Site
REI.MAP SOth percenlite
Variant b 1 jrge
Municipal Waste
Jombustor
Variant b Small
Municipal Waste
Combustor
large Commercial HM1
Large Hospital HMI
Small Hospital HMI
1-arge Hospital HMI
wet scrubber)
Small Hospital HMI
wet scrubber)
Large Coal-fired Utility
Boiler
Medium Coal-fired
Jtility Boiler
Small Coal-fired Utility
toiler
Medium Oil-fired Utility
Boiler
Chlor-alkah plant
Predicted Ingestion (mg/kgAI,iy) for llrb.in High l;ml
2 Skm
Child Aduli
Value %ISC Value %ISC
1 8E-05 76% 1 IT.06 >%
73E-06 40% 10L-06 1%
72E-06 .19% 101-06 1%
2 1E-05 81% 12I.-06 6%
56E-06 22% 101. -06 0%
49E-06 11% 10E-06 0%
44E-06 1% 301, -Oft 0%
7 IR-06 18% 101,06 }'(
60E-06 26% MM.-06 ()'/f
5.2E-06 IS1* 10P.06 0%
45E-06 2% 10I.-06 ()%
1 5E-04 97% 7 1F-06 VW
10 km
Child Adult
V.iluc %ISC Value %ISC
1 II. -OS 61% 1 IE-06 1%
S 2I--06 16% 10E-06 0%
4«r-o6 8% ior-:-06 o%
721-06 18% IOIi-06 1%
4 61 -06 1% 1 OE-06 0%
4SI--06 2% 10E.-06 0%
1 41 -06 0% 1 OK-06 0%
s 11 -06 16* .10E-06 0%
541-06 19% J OK-06 0%
48l.-(Ki 1% .10E-06 0%
4SI-.-06 |% 30E-06 0%
2 ll-.-O.s 79% .16E-06 18%
25km
Child Adult
Value %ISC Value %ISC
69E-06 36% 3.0E-06 1%
47E-06 6% .10E-06 0%
45E-06 2% 30E-06 0%
5 IE-06 14% 3.0E-06 0%
44E-06 1% 30E-06 0%
44E-06 0% 30E-06 0%
44E-06 0% 30E-06 0%
52E-06 15% 30E-06 0%
5 IE-06 11% 30E-06 0%
45E-06 .1% 30E-06 0%
44E-06 0% 30E-06 0%
88E-06 50% 32E-06 6%
-------
Table 3-18 (continued)
Western Site RKLMAP 50th and 90th Perccntiles
Predicted Ingestion (mg/kg/day) for Urban High End
Western Sue
RI-LMAP 90th perccmilc
Variant h l-arge
Municipal Waste
Combuslor
Variant h Sraill
Municipal Waste
Combustor
I-arge Commercial HMI
Urge Hospital HMI
Small Hospital HMI
Urge Hospital HMI
(wet scrubber)
Small Hospital HMI
(wet scrubber)
Large Coal-fired Ulilily
Boiler
Medium Coal-fired
Utility Boiler
Small Coal-fired Utility
Boiler
Medium Oil-fired Utility
Boiler
Chlor-alkali plant
Predicted Ingestion (mg/kg/day) Inr Urban High 1 ml
2 5km
Child Adult
Value %KC V.-iluc '/,ISC
2 'P.-05 61% M\ -06 S%
1 2E-05 25% 1 H',-06 1%
1 2E-05 24% 1 IE-06 1%
2 7E-05 68% 1 2K-06 6%
9 9E-06 12* 111 06 0%
9 3E-06 6% 1 1 l-:-06 0%
88E-06 0% 1 IT.-06 ()'/,
1 II:-(K 21% 1 11-06 l»
I.OE-OS 15% J II. -06 0%
95E-06 8% 1 ll>06 0%
88E-06 \% 1 II-.OA 0%
1 5F.-04 94% 7 4I,-06 58%
10 km
Child Adult
V.ilm- %ISC Value %ISC
1 (,| -OS 44% 1 lh-06 1%
9 (.1 -06 9%. 1 1 [',-06 0%
9 Hi Oft 4% 1 IIi-06 0%
1 1 1 -OS 24% 1 1 li-06 1 %
8 91 -Oh 2% 3 1 1--06 0%
XXI -06 I'/r t IE-06 0%
87l.-0f> 0% 1 IT-06 07n
9 f.l 06 ')% 3 1 1--06 0%
9 SI 06 11% 1 IE-06 0%
9 II 06 4% 3 IE-06 0%
8 XI 06 1% 1 IE-06 0%
2 61 .-05 66% 1 7E-06 17%
25km
Child Adult
Value %ISC Value %ISC
1 IE-OS 22% 3 IE-06 1%
90E-06 3% 3 IE-06 0%
88E-06 1% 3 IE-06 0%
94E-06 8% 3. IE-06 0%
88E-06 0% 3. IE-06 0%
87E-06 0% 3 IE-06 0%
87E-06 0% 3. IE-06 0%
9.5E-06 8% 3. IE-06 0%
94E-06 7% 3 IE-06 0%
88E-06 1% 3 IE-06 0%
87E-06 0% 3. IE-06 0%
1 3E-05 34% 3 3E-06 6%
3-31
-------
Table 3-19
Western Site RELIMAP 50th and 90th Percentiles
Predicted Ingestion (mg/kg/day) for Subsistence Fisher
Western Site
RBLMAP 50)h pcrcennlc
Variant b Large
Municipal Waste
Combustor
Variant b.Stnall
Municipal Waste
Combustor
Urge Commercial HMI
Large Hospital HMI
Small Hospital HMI
Large Hospital HMI
(wet scrubber)
Small Hospital HMI
wet scrubber)
1-arge Coal-fired Utility
Boiler
Medium Coal-fired
Utility Bmler
Small Coal-fired Utility
Boiler
Medium Oil-fired Utility
Joiler
~hlor-alkali plant
Predicted Ingestion (mg/kg/d.iy) for Subsistence Hshrr
2 5km
Child Adult
Value %ISC Value r/(ISC
7211-04 Rl% > 2f.-(H HIV,
28E-04 55% 20F.-04 55%
28F.-04 56% 21104 55%
1 1E-01 89% 8 1K-04 89%
1 9E-04 35% 1 4I.-04 15%
1 5E-04 19* 1 II -04 \<>%
1 1F.-04 1% 9 M OS 1%
2SI--04 51% 1 9F-04 5I',«.
1 9F.-04 .15% 1 41-04 "',<
1 6F-04 21% 1 2F-04 2V/,,
1 1F.-04 2% 9 M.-05 2%
8 2F.-0.1 9R% 601.01 1K%
10 km
Child Adult
V.ilvic %ISC Value *ISC
4 M.-O4 72* 1 lli-04 72%
1 M-04 2^% 1 2F.-04 24%
1 .1K-04 ir/f, 1 OF.-04 11%
26I.-04 52% 1 9F.-04 52%
1 11 04 6% 9 7F.-05 6%
1 11 .04 1* 9 4I--05 1%
i :r 04 0% 9 21- -os o%
1 61 04 21% 1 2E-04 21%
1 7I--04 27% 1 2F-04 26%
141-04 12% 1 OF.-04 12%
1 11 04 2% 9 1F.-05 2%
96F-04 87% 70E-04 87%
25km
Child Adult
Value %ISC Value %ISC
2 .1E-04 46% 1 7E-04 45%
1 lfi-04 8% 9 9E-05 8%
1 JtH-04 3% 9 4E-05 .1%
1 5E-04 19% 1 IE-04 19%
1 -1F.-04 1% 9. IE-OS 1%
1 2E-04 1 % 9 2E-05 1 %
1 2E-04 0% 9 IE-OS 0%
1 SE-04 20% 1 IE-04 20%
1 SE-04 18% 1. IE-04 18%
1 1F.-04 4% 9 SE-OS 4%
1 2E-04 1 % 9 2E-05 1 %
.1 IE-04 60% 22E-04 59%
-------
Table 3-19 (continued)
Western Site RELMAP 50th and 90th Percentiles
Predicted Ingestion (mg/kg/day) for Subsistence Fisher
Western Sue
RF.I.MAP Wth percenlile
Variant h l.arpc
Municipal Waste
i'ombustor
Vananl h Small
Municipal Waste
Tombuslor
l-arge Commercial HMI
targe Hospital HMI
Small Hospital HMI
Large Hospital HMI
(wet scrubber)
Small Hospital HMI
(wcl scrubber)
I jrge Coal-fired Utility
Bolter
Medium Coal-fired
Utility Holler
Small Coal- fired Utility
Boiler
Medium Oil fired Utility
Boiler
Chlor-alkali plant
Predicted Ingestion (mg/kp/day) for Subsidence 1 isln-r
2 Urn
Child A.luli
Value %ISC V;iluc '/MSC
8 VMM 6R% 641--04 6K%
4 1MM 35% 1 21 -04 IV*
44R-04 16% 12F.-04 m
1 1F.-03 78% 95F-04 7X1!
35E-04 19* 2 61; 04 !')%
3.IP.-04 9% 2 M-.-04 9',f
2RE-04 1% 2 II, -04 \'l,
4 IE-04 12* 10U-04 11%
15F.-04 19* 26F.-04 I1)'/,,
32F.-04 12% 211-04 II'/S
2.9E-04 1% 211,04 1%
8.1E-0.1 97% 6IF.-01 97%
10km
Child Adult
V.iluc %1SC Value %ISC
f. If (14 M% 44I-.-04 ST*
1 21 04 1 V/r 2 411-04 1 2%
101.04 6% 2 2F.-04 6%
4?r. 04 12% 1 1F-04 12%
29MM 1% 2IF.-04 1%
2 91. -04 1% 2 ir-04 1%
2XF-04 0% 2 IF.-04 0%
121-04 12% 2 1F.-04 11%
1 11. -04 14%, 24E-04 14%
1 OF-04 6% 2 2E-04 6%)
2 HI 04 17n 2 IF:-04 1%
1 IF.-Ol 75% 82E-04 75%
25km
Child Adult
Value %ISC Value %ISC
19E-04 27% 28E-04 27%
29E-04 4% 22E-04 4%
29E-04 1% 2 IE-04 1%
3 IE-04 9% 23E-04 9%
28E-04 1% 2.IE-04 1%
28E-04 0% 2 IE-04 0%
28E-04 0% 2 IE-04 0%
1 IE-04 10% 2. IE-04 10%
.1 IE-04 9% 23E-04 9%
29E-04 2% 2. IE-04 2%
28E-04 0% 2 IE-04 0%
47E-04 39% 3.4E-04 39%
-------
Table 3-20
Western Site RELMAP 50th and 90th Percentiles
Predicted Ingestion (mg/kg/day) for Recreational Angler
Western Site
RF.I.MAP 50th perccntile
Predicted Ingestion (mg/kg/day) for Recreational Angler
25km
Child AJull
Value %ISC Value %ISC
Variant b Urge Municipal Wasle CombuMor 261. -04 XVf
Varianl b Small Municipal Waste CombuMor 9 9I.-05 57%
Urge Commercial HMI 1 OR -04 57%
Urge Hospital HMI 4 IF.-04 90%
Small Hospital HMI 6 Xh-05 17%
Urge Hospital HMI (wet scrubber) 5 3I.-05 20%
Small Hospital HMI (wel scrubber) 4 4I.-05 2%
Urge Coal-fired Utility Boiler "OI-.-05 51%
Medium Coal-Fired Utility Boiler ft 7I-.-05 16%
Small Coal-fired Utility Boiler 561.05 24%
Medium Oil-fired Utility Boiler 44105 2%
Chlor-alkali plant
i on-oi vn,
10 km
fluid Adult
Value %ISC Value %ISC
1 6H-04 71%
5 8F.-05 26%
4 9E-05 1 3%
9 2E-05 .54%
4 6B-05 6%
4 4F.-05 3%
4 3F.-05 0*
5 6R-05 24%
5 9F.-05 28%
4 9B-05 1 2%
4 4F.-05 2%
1 5F.-04 88*
25km
Child Adult
Value %ISC Value %ISC
8 IE-05 47%
4 7E-05 8%
4 4E-05 3%
5 4E-05 20%
43E-OS 1%
43E-0.5 1%
4 3E-05 0%
54E-05 21%
5 3E-05 19%
4 5E-05 4%
4.3E-05 1%
I.IE-04 61%
Western Site
RF.I.MAP 'X)th percentile
Predicted Ingestion (mg/kg/day) for Recreational Angler
2 5km
Child A. lull
Value %ISC Value %ISC
Vananl b Large Municipal Waste Combustor 1 2F -04 6K%
Vananl b:Small Municipal Wasle Cnmbuslor 1 6U-04 16%
Urge Commercial HMI 1 6(5-04 W/,
Urge Hospital HMI 4 7P-04 79%
Small Hospital HMI 1 M -04 20%'
Urge Hospital HMI (wel scrubber) 1 II.-04 10%
Small Hospital HMI (wel scrubber) 1 OI.-04 1 %
1 -argc Coal-fired Utility Boiler 1 5F-04 M'k
Medium Coal-fired Utility Boiler MM)4 20%
Small Coal-fired Utility Boiler 111-04 \}7,
Medium Oil-fired Utility Boiler 1 01. (M 1%
Chlor-alkali plan
i or.-o.t <>T/<
10 km
( lnl.l Adult
Value %ISC Value %ISC
2 2F.-04 54%
1 2E-04 13%
1 IE-04 6%
1 5E-04 33%
1 OF.-04 3%
1 OF.-04 1 %
1 OF.-04 0%
1 IF.-04 12%
1 2F.-04 14%
1 IF.-04 6%
1 OF.-04 1%
4 IK-04 75%
25km
Child Adult
Value %ISC Value %ISC
1 4E-04 27%
1 OE-04 4%
IOE-04 1%
1 IE-04 10%
IOE-04 1%
1 OE-04 0%
1 OE-04 0%
1 IE-04 10%
I.IE-04 9%
1 OE-04 2%
1 OE-04 0%
1 .7E-04 40%
-------
Table 3-21
Eastern Site RELMAP 50th and 90th Percentiles
Predicted Inhalation
Intern Site
RFiLMAI' Will percenlilc
Variant h l-arge Municipal Waste Cnmhustor
Vananl h Small Municipal Waste Comhuslor
l-arge Commercial HMI
1-arge Hospital HMI
Small Hospital HMI
1 .arge Hospital HMI (wet scrubber)
Small Hospital HMI (wet scrubber)
1 .arge Coal-fired Utility Boiler
Medium Coal-fired Utility Boiler
Small Coal-fired Ulilily Boiler
Medium Oil-fired Utility Boiler
Thlor-alkali plant
2 Skm
Child Adult 1 nil lime A .1 H 1 I
I'.irl lime
Value 7rISC V.iluc '/iISC V.iluc *ISC
1 6I.-06 V/n 4 9F.-07 vt 1 \\ -07 Vk
1 6F:-<)6 1% 4XF.-07 I'/,. 121-07 1%
1 6I-.-06 n 4XI-.-07 1% 1 2I--07 1%
1 6E-06 1» 4 9F-.-07 W 1 11 -07 1%
1 6E-06 0% 4 RI-.-07 07,, 1 2I-.-07 0%
1 6E-06 0% 4 8F.-07 O'/f. 1 21 07 07r
1 6E-06 0% 4 8F--07 0% 1 21- 07 0%
i 6K-06 n% 4 xi- -07 w/, ?2M>7 o*
1 6E-06 0» 4 8C.-07 0% 1 21', -07 0%
1 6E-06 0% 4 Kl-,-07 0* .1 2l',-()7 (Yf,
1 6F.-06 0% 4 8E-07 (Y/,. 1 2I--07 0%
17E-06 58% 1 H-,-06 S8% 761-07 S87,.
Predated Inhalalion for Fiastcrn Site
10km
Child Adult 1 ull time Adult
Part time
Value %1SC Value %1SC Value %ISC
1 6I.-06 2% 4 9E-07 2% 1 1E-07 2%
1 6E-06 0% 4 8E-07 0% 1 2E-07 0%
1 6F.-06 0% 4 8E-07 0% 1 2E-07 0%
I6E06 1% 4XE-07 1% 3 2F.-07 1%
1 M -06 0% 4 SI--07 0% 1 2F.-07 0%
1 6I-.-06 0% 4 8H-07 0% .1 2F--07 0%
1 6K-06 0% 4 8I:.-07 0% 1 2R-07 0%
1 6H-06 0% 4 8K-07 0% 3 2F.-07 0%
1 611-06 0% 4 8K-07 0% 3 2FI-07 0%
1 61- -06 0% 4 8I--07 0% 3 2R-07 '0%
1 6F:,()6 0% 4 8U-07 0% 3 2F.-07 0%
20F.-06 21% 60E-07 21* 40E-07 21%
25km
Child Adult Full lime A d u 1 I
Part lime
Value %ISC Value %ISC Value %ISC
1 6E-06 1% 48E-07 1% 3 2E-07 1%
1 6E-06 0% 4 8E-07 0% 3.2E-07 0%
1 6E-06 0% 4 8E-07 0% 3.2E-07 0%
1 6E-06 0% 4 8E-07 0% 3 2E-07 0%
1 6E-06 0% 4 8E-07 0% 3.2E-07 0%
1 6E-06 0% 4 8E-07 0% 3.2E-07 0%
1 6E-06 0% 4 8E-07 0% 3 2E-07 0%
1 6E-06 0% 4 8E-07 0% 3 2E-07 0%
1 6E-06 0% 4 8E-07 0% 3 2E-07 0%
1 6E-06 0% 4.8E-07 0% 3 2E-07 0%
1 6E-06 0% 4 8E-07 0% 3 2E-07 0%
1 7E-06 8% 5 2E-07 8% 3.4E-07 8%
Eastern Sue
RELMAP 90th perccnnle
Vananl b large Municipal Waste Combtislor
Vananl h Small Municipal Wasie Combuslor
I .arge Commercial HMI
(.arge Hospital HMI
Small Hospital HMI
Ijirge Hospital HMI (wel scrubber)
Small Hospital HMI (wet scrubber)
1 jrge Coal-fired Ulihty Boiler
Medium Coal-fired Utility Boiler
S trail Coal-fired Utility Boiler
Medium Oil-fired Utility Boiler
Chlor alkali plant
2 Skin
Child Adull I ull lime Adult
Part lime
Value %ISC Value »ISC Value %ISC
1 7F.-OA 1% SIT, 07 3% 34I.-07 V/i,
1 6I-.-06 1% 50I.-07 lr/r * V 07 \%
1611-06 l» SOI -07 I7r 1 11-07 1%
I7I;-06 1» S ||>07 v:'f 141 07 V/,
1 6I.-06 0'* 4 <)l -07 0% 1 W. 07 ()'/<
1 6r-(Xi 0* 4')l-07 (Yi 1 IF 07 0%
1 f>F.-Of) 0% 4 "l|- 07 0* 111-07 0%
1 6F.-06 07.' 4'>l-()7 0% 111. -07 0*
1 6P.-06 07r 4 91 -07 0% 1 H-,-07 0%
1 6F.-06 0% 4 "1,07 0% 111. (17 0%
1 6E-06 0% 49U-07 ()'* 1 11. -07 0%
18I--06 57% 1 II": 06 57'^ 77I.-07 57*
Predicted Inhalation for Eastern Site
10km
Child Adull Full time Adult
Part lime
Value %1SC Value %ISC Value %ISC
1 7I--06 2% 5 OI:.-07 2% 3 4E-07 2%
1 6E-06 O% 4 9E-07 0% 3 3F.-07 0%
1 6E-06 0% 4 9F.-07 0% 3 3E-07 0%
1 6E-06 1% 50E-07 \% 13E-07 1%
16106 0% 49I-.-07 0% 3 1E-07 0%
1 Mi-06 0% 4 9F.-07 0% 1 1E-07 0%
1 61.-06 0% 49F07 0% 3 3F.-07 0%
1 6E-06 0% 4 9E-07 0% 3 3E-07 0%
1 6Fi-06 0% 4 9E-07 0% 3 31: -07 0%
1 6E-06 0% 4 9E-07 0% 3 3I--07 0%
1 6F.-06 0% 4 9E-07 0% 3.3E-07 0%
201.06 21* 62E-07 21% 4.IE-07 21%
25km
Child Adull Full lime Adult
Part time
Value %FSC Value %ISC Value %ISC
1 6E-06 1% 5.0E-07 1% 3.3E-07 1%
1 6E-06 0% 4 9E-07 0% 3.3E-07 0%
1 6F.-06 0% 4.9E-07 0% 3 3E-07 0%
1 6E-06 0% 4.9E-07 0% 3 3E-07 0%
1 6E-06 0% 4 9E-07 0% 3 3E-07 0%
1 6E-06 0% 4 9E-07 0% 3 3E-07 0%
1 6E-06 0% 4.9E-07 0% 3.3E-07 0%
1 6E-06 0% 4 9E-07 0% 3 1E-07 0%
1 6E-06 0* 4 9E-07 0% 3 3E-07 0%
1 6E-06 0% 4 9E-07 0% 3.3E-07 0%
1 6E-06 0% 4 9E-07 0% 3.3E-07 0%
1 8E-06 8» 5.3E-Q7 8% 3 5E-07 8%
-------
Table 3-22
Western Site RELMAP 50th and 90th Percentiles
Predicted Inhalation
Western Sue
RELMAP 50lh pcrcenlile
Variant b.Ijirge Municipal Waste Combuslor
Variant b'Small Municipal Waste CombuMor
Large Commercial HMI
Large Hospital HMI
Small Hospital HMI
Large Hospital HMI (wet scrubber)
Small Hospital HMI (wet scrubber)
Large Coal-fired Utility Boiler
Medium Coal-fired Utility Boiler
Small Coal-fired Utility Boiler
Medium Oil-fired Utility Boiler
Chlor-alkali plant
2 Slcm
Chilil Ailuli lull lime Adult Part lime
Vnlue %ISC Value %1SC Value %ISC
1 61 -06 2% 4 7I--07 2% 1 2K-07 2%
1 S|. -lift |% 46F.-07 \% 1 II.-07 1%
1 S|- (X. 1% 4711-07 1% 3 IF.-07 1%
1 61 .-06 2% 4 7I--07 2% 3 2U-07 2%
1 5I-.-06 0% 4 6I--07 0% 3 IF.-07 0%
1 51-06 0% 46107 0% 1 ll:.-07 0%
1 SI-.- 06 0% 46F-07 0% 3 IE-07 0%
151.06 0'/0 4 61 ,-07 0% 1II-.-07 0%
1 SI.-06 0% 46I-.-07 0% 1 IE-07 0%
1 SI-.-I16 0% 46F.-07 0% 1 II-.-07 0%
1 51 .-06 0% 46IMI7 0% 1 IE 07 0%
1 3I-.-06 54% 1 OK-06 54% 6 8F-07 54%
Predicted Inhalation For Western Site
10km
Child Adult Full lime Adult Part time
Value %ISC Value %ISC Value %ISC
1 5E-06 2% 47K-07 2% 3 IE-07 2%
1 5E-06 0% 46F.-07 0% .1 IE-07 0%
1 5E-06 0% 46E-07 0% 3. IE-07 0%
1 SE-06 1% 46F.-07 1% 3 IE-07 1%
1 5I--06 0% 46F.-07 0% 3 IE-07 0%
1 5E-06 0% 46E-07 0% 3 IE-07 0%
1 SE-06 0% 46F.-07 0% 3 IE-07 0%
1 5F.-06 0% 46F.-07 0% 3 IE-07 0%
1 5E-06 0% 4 6E-07 0* 3 IE-07 0%
1 SE-06 0% 46F.-07 0% 3 IE-07 0%
1 5E-06 0% 46R-07 0% 3 IE-07 0%
1 8E-06 16% 5 5E-07 16% 3 7E-07 16%
25km
Child Adult Full time Adult Part time
Value %ISC Value %ISC Value %ISC
1 SE-06 1% 47E-07 1% 3 IE-07 1%
1 5E-06 0% 4 6E-07 0% 3 1 E-07 0%
1 5E-06 0% 4 6E-07 0% 3 1 E-07 0%
1 5E-06 0% 4.6E-07 0% 3 1 E-07 0%
1 5E-06 0% 4 6E-07 0% 3 1 E-07 0%
1 5E-06 0% 46E-07 0% 3 IE-07 0%
1 5E-06 0% 4 6E-07 0% 3. 1 E-07 0%
1.. SE-06 0% 46E-07 0% 3 IE-07 0%
I5E-06 0% 46E-07 0% 3 IE-07 0%
1 5E-06 0% 46E-07 0% 3. IE-07 0%
1.5E-06 0% 46E-07 0% 3. IE-07 0%
1 6E-06 6% 4.9E-07 6% 3 3E-07 6%
Western Site
REUrfAP 90th pcrccntile
Variant b Ijtrge Municipal Waste Combuslor
Variant b Small Municipal Waste Combustor
Lirge Commercial HMI
l.arge Hospital HMI
Small Hospital HMI
Urge Hospital HMI (wet scrubber)
Small Hospital HMI (wet scrubber)
Ltrge Coal-fired Utility Boiler
Medium Coal-fired Utility Boiler
Small Coal-fired Utility Boiler
Medium Oil-fired Utility Boiler
Chlor-alkali pliint
2 skm
Cliilil Ailuli l-ull lime Adult Part lime
Value r/ISC Value %ISC Value %ISC
1 6!;-6 2% 4 8I-.-07 2% 3 2K-07 2%
1 51,06 Wt, 47I>07 0% 3IH-07 0%
1 Si; 06 0'*- 4 7I--07 0% 3 1 li-07 0*
1 51 (Hi 0% 4 71, -07 0% 31|;-07 0%
1 S|. Oft 0'4 4 7P-07 0% 3 IF.-07 0%
ISI.06 0% 471-07 n% < IF.-07 0%
151(16 O'/r 471-07 07r. 3 li:-07 0%
1 51-,-Ofi O'/,. 471.07 0% 1 IR-07 0%
1 41. -06 54% 1 OI-:-06 54% 6 8H-07 54%
Predicted Inhalation for Western Site
10km
Child Adult Full lime Adult Part lime
Value %ISC Value %ISC Value %ISC
1 6F.-06 2% 4 8F.-07 2% 3 2E-07 2%
1 5F.-06 0% 47E-07 0% 3 IE-07 0%
1 SE-06 0% 4 7F.-07 0% 3 1 E-07 0%
1 6F.-06 \% 47E-07 1% 3 IE-07 1%
1 5F.-06 0% 47F.-07 0% 3 IE-07 0%
1 Sh-06 0% 47F.-07 0% 3 IE-07 0%
1 5E-06 0% 47E-07 0% 3. IE-07 0%
1 5E-06 0% 47E-07 0% 3 IE-07 0%
1 SK-06 0% 47l-:-07 0% 3 IE-07 0%
1 5F.-06 0% 4 7E-07 0% 3 1 E-07 0%
1 5F.-06 0% 47F.-07 0% 3 IE-07 0%
1 8E-06 16% 56E-07 16% .3 7E-07 16%
25km
Child Adult Full time Adult Part lime
Value %ISC Value %1SC Value %ISC
1 6E-06 1% 47E-07 1% 3 2E-07 1%
1 5E-06 0% 47E-07 0% 3 IE-07 0%
1 5E-06 0% 47E-07 0% 3. IE-07 0%
I.5E-06 0% 47E-07 0% 3 IE-07 0%
1 5E-06 0% 4.7E-07 0% 3 IE-07 0%
I.5E-06 0% 47E-07 0% 3 IE-07 0%
1 5E-06 0% 47E-07 0% 3 IE-07 0%
I.5E-06 0% 47E-07 0% 3. IE-07 0%
1 SE-06 0% 47E-07 0% 3 IE-07 0%
1 SE-06 0% 47E-07 0% 3 IE-07 0%
1 .SE-06 0% 4 7E-07 0% 3 1 E-07 0%
1 6E-06 6% 5.0E-07 6% 3 3E-07 6%
-------
fruiting vegetables the bulk of mercury is also modeled to be the result of uptake of mercury from the
atmosphere into the plant.
Although not shown in the tables below, divalent mercury accounts for approximately 90% of the
total mercury intake for the agricultural scenarios, with the rest being methylmercury. This partitioning is
reflective of the predicted speciation of mercury in the ingested plant and animal products.
The differences between facilities are due to differences in parameters that affect effective stack
height, and the assumed total mercury emission rate. The speciation of mercury emissions is not an
important factor because the speciation only affects the predicted deposition rates, not the total mercury air
concentrations.
3.2.3 Urban Scenarios
With the exception of the child exhibbiting pica behavior in this scenario (urban high end child),
the predicted mercury exposures in the urban scenarios are generally an order of magnitude lower than
those for the agricultural scenarios. This reflects the lower ingestion rates assumed for locally grown plant
products. As for the agricultural scenarios, divalent mercury is the primary form of mercury to which they
receptors are exposed.
The larger contribution of the local sources in these scenarios reflects the fact that only for the
urban high end is consumption of plant products assumed: for the other urban scenarios exposure to
mercury from the local source is assumed to be solely through ingestion of soil. The contributions of the
local source shown for the urban scenarios thus reflect the contribution of the local source on the soil
concentrations, which themselves are driven by the mercury deposition rates. The mercury deposition rates
are generally driven by the assumed speciation of mercury emissions.
The contribution of the local source when pica behaviour is exhibbited (urban high end child)
reflects the contribution of the local source to the soil concentration.
3.2.4 Fish Ingestion Scenarios
The predicted mercury exposure in the fish ingestion scenarios (high-end fisher and recreational
angler) is dominated by exposure through ingestion of fish, even though some exposure through ingestion
of plant products is also assumed. Methylmercury is the primary form of mercury to which these receptors
are exposed. The fish concentrations are driven by the predicted dissolved methylmercury concentrations
in the surface water, which themselves are driven by the watershed soil concentrations and the waterbody
atmospheric mercury deposition rate.
For several of the facilities at both the eastern and western sites, the majority of the exposure to
mercury is predicted to be due to the local source for the waterbody located 2.5 km from the facility. This
is also true for some facilities at both 10 km and 25 km. These results reflect the contribution of the local
source to total mercury deposition onto the waterbody and the watershed soils.
The contribution of the local source is larger at the western site because both the regional and pre-
industrial deposition rates are lower than at the eastern site, while the results for the local source (using
ISC) are more similar. However, the total mercury exposure is approximately twice as low at the drier
western site compared to the eastern site due primarily to differences in meteorology.
3-37
-------
3.3 Issues Related to Predicted Mercury Exposure Estimates
In the modeling effort exposure for six different hypothetical adult humans was
modeled. Atmospheric emissions of anthropogenic origin, local background and regional atmospheric
mercury may not be the only sources of mercury exposure. Individuals can be exposed to mercury from
other sources such as occupation and consumption of non-local (e.g., marine) fish. Quantitative estimates
of these sources are presented in the following chapters of this Volume. This section considers the logic of
adding exposure from these additional sources in an assessment.
Occupational mercury may be an important source of exposure. This source may apply to any
hypothetical adult modeled here with the exception of the subsistence farmer. For a given area with a
relevant industrial base, it may be appropriate to consider these exposures for members of the population,
when assessing mercury exposures.
In the modeling effort several hypothetical humans were assumed not to consume locally-caught
fish. These hypothetical individuals include: a subsistence farmer and child, a rural home gardener, and
the urban dwellers. For these hypothetical individuals, it is reasonable to assume that some fraction of the
individuals they represent will consume marine fish. For this marine fish consuming subset, the ranges of
methylmercury exposure from marine fish consumption that are estimated later in this Volume are
applicable. Methylmercury from marine fish consumption, if considered, is an incremental increase over
the estimated intakes.
In the modeling effort several hypothetical individuals were assumed to consume high levels of
locally caught fish. These individuals include: an angler, who is assumed to consume 60 grams of local
fish/day, a child, who is assumed to consume 20 grams of local fish/day and a recreational angler who is
assumed to consume 30 grams fish/day. Since these hypothetical individuals consume high levels of local
fish, it is probably inappropriate to consider exposure through an additional fish consumption pathway.
Although it is reasonable to assume that some individuals consume both local and other fish; for example.
Fiore et al. (1989) documented the consumption of both self-caught and purchased fish in U.S. anglers,
these data are not combined in this assessment.
The initial conditions assumed before the facility is modeled (referred to here as "background") are
potentially critical to the total mercury exposure. This is particularly important because the magnitude of
the contribution of a local source to the total may be used to assess its impact. A delicate balance is
required when including such a "background" in the analysis. This is because it is not just a matter of a
local source's contribution to this background, but the total impact of background plus the local source that
is ultimately the primary concern. Overestimating the background will result in a concurrent decrease in
the contribution of a given local source, but may result in exceeding thresholds that would not be exceeded
if lower estimates of background are assumed. Resolution of this issue is not within the objectives of the
current report; it is noted, however, that there is no available guidance on how to incorporate background
in exposure assessment. For a local scale mercury exposure assessment it is important to measure mercury
concentrations in various media.
The impact of the uncertainty in the predicted air concentrations and deposition rates for each
facility is most important for the fish ingestion and pica child scenarios. This is because, in general, the
local source does not contribute significantly to the mercury exposure for the agricultural and urban
scenarios. The exception to this pattern is the chlor-alkali model plant. In this case, the low assumed
mercury release height results in the facility having a substantial impact on the mercury air concentrations
close to the facility.
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3.4 Summary Conclusions
The contribution of the local source, compared to background and the regional contribution, is
larger at the western, drier site than at the eastern site. This is because both the regional impact
and background values are much lower at the western site than is prdicted to occur for the local
source. However, the magnitude of the total exposure at the western site is about half that at the
eastern site due to the drier meteorology at the western site.
For the agricultural scenarios, it is generally the background or regional sources that account for
the majority of total mercury exposure. This is because the dominant pathway of mercury
exposure in these scenarios is the ingestion of plants, which accumulate most of their mercury
from the air, and most of the local sources are predicted to have little impact on the local average
air concentrations compared to the regional sources.
Most of the mercury to which the hypothetical receptor is exposed in the agricultural and urban
scenarios is divalent mercury. This is because most of the mercury in plants and soil is predicted
to be of this form. In contrast, in the fish ingestion scenairos methylmercury is the primary form of
mercury to which the receptor is exposed.
For the fish ingestion scenarios, the local sources are predicted to account for the majority of the
total mercury exposure for waterbodies close to the facility. This is particularly true for the
western site, where the background and regional contribution tothe total mercury deposition are
lower.
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4. POPULATION EXPOSURE FISH CONSUMPTION
4.1 Fish Consumption among the General U.S. Population
Fish bioaccumulate methylmercury through the freshwater aquatic and marine food-chains. Mercury-
contaminated phytoplankton and zooplankton are consumed by planktivorous fish (referred to in other parts
of this Volume at trophic level 3 fish). Methylmercury is thought to bioaccumulate in this group as well as
in the piscivorous fish. Both marine and freshwater fish bioaccumulate methylmercury in their muscle tissue.
Consumption of these methylmercury-contaminated fish results in exposures to human populations. Additional
data have become available between 1995 and 1997 that permit estimates of mercury consumption from marine
mammals and birds by populations living in the far Northern latitudes.
Consumption of fish is highly variable across the U.S. population unlike consumption of other dietary
components, such as bread or starch, that are almost ubiquitously consumed. This chapter presents an estimate
of the magnitude offish consumption in both the general U.S. population and in specific subpopulations (e.g.,
children and women of child-bearing age). This estimate identified the portion of the population that consumes
fish and shellfish. It also provides estimates of species of fish consumed and the quantity of fish consumed
based on cross-sectional survey data. Use of a national data base differentiates data in this Chapter from site-
specific assessments. Data presented in this Chapter differ from site-specific assessments in which
consumption of contaminated local freshwater fish are included.
Inclusion offish in the diet varies with geographic location, seasons of the year, ethnicity, and personal
food preferences. Data on fish consumption have been calculated typically as either on "per capita" or "per
user" basis. The former term is obtained by dividing the supply of fish across an entire population to establish
a "per capita" consumption rate. The latter term divides the supply of fish across only the portion of the
population that consumes fish, providing "per user" rates of consumption.
Identifying differences in fish consumption rates for population groups can be achieved through
analysis of dietary survey data for the genera! United States population and specified subpopulations; e.g.,
some Native American tribes, recreational anglers, women of childbearing age, and children. The United
States Department of Agriculture (USDA) has conducted a series of nationally-based dietary surveys, including
the 1977-1978 Nationwide Food Consumption Survey and the Continuing Surveys of Food Intake by
Individuals (CFSII) over the period 1989 through 1995 (CFSH 89-91; CSFH, 1994; CFSH, 1995). In addition,
data from the third National Health and Nutrition Examination Survey (NHANES HI), conducted between
1988 and 1994, provide estimates of fish consumption patterns in the early 1990s. Analyses of fish
consumption patterns among the general U.S. population and selected age/gender groupings are described
below. Fish consumption rate data from specific Native American tribes and angling populations are identified
and used to corroborate the nationwide fish consumption data.
4.1.1 Patterns of Fish Consumption
Although the consumption frequency of fish is low compared with staple foods such as grain products,
dietary intake offish can be estimated from survey data. The initial issue of how to estimate fish consumption
depends to a great extent on the choice of dietary assessment method. Available techniques include long-term
dietary histories, questionnaires to identify typical food intake or short-term dietary recall techniques and
questionnaires on food frequency. The first consideration is to obtain dietary information that reflects typical
fish consumption. A true estimate of methylmercury intake from fish is complicated by changes in fish intake
over time, differences in species of fish consumed, variation in the methylmercury concentration in a species
of fish, and broad changes in the sources of fish entering the U.S. market place. For example, increases in
aquaculture or fishfarming and increased reliance on imported fish for domestic consumption may affect
consumption estimates. Temporal variation in dietary patterns is an issue to consider in the evaluation of short-
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term recall/record data. For epidemiological studies that seek to understand the relationship of long-term
dietary patterns to chronic disease, typical food intake is the relevant parameter to evaluate (Willert, 1990).
Because methylmercury is a developmental toxin that may produce adverse effects following a
comparatively brief exposure period (i.e., a few months rather than decades), comparatively short-term dietary
patterns can have importance. Consequently, estimation of recent patterns of methylmercury consumption
from fish is the relevant exposure for the health endpoint of concern. Because it is not possible to precisely
identify the period of development during which mercury is likely to damage the nervous system of the
developing fetus or growing child, exposure of women of childbearing age or your children to mercury via
consumption of fish is a cause for concern.
This chapter describes the distribution of fish intakes for the general population and for subpopulations
defined by age or gender; e.g., women of child-bearing age. Estimates of the number of women who are
pregnant in any given year are based on methods shown in Appendix B. The analysis is not intended to
estimate fish consumption by an individual and relate it to an individual's health outcomes. Dietary
questionnaires or dietary histories may identify broad patterns of fish consumption, but these techniques
provide less specific recollection of foods consumed such as the species offish eaten. Likewise estimates of
the quantity of fish consumed become less precise as the eating event becomes more remote in time. The
selection of a dietary survey method to describe fish intakes by the subpopulation of interest requires a
balancing the specificity of information collected with the generalization of short-term dietary patterns to
longer-term food intakes.
After the appropriate period of fish intake is selected, the second area of concern becomes the variation
in the methylmercury concentrations of the fish consumed. A central feature of food intake among subjects
with a free choice of foods is the day-to-day variability in foods consumed superimposed on an underlying food
intake pattern (Willett, 1990). In epidemiology studies, an individual's true intake of a food such as fish could
be considered as the mean intake for a large number of days. Collectively, the true intakes by these individuals
define a frequency distribution for the study population as a whole (Willett, 1990). It is rarely possible to
measure a large number of days of dietary intake for individual subjects; consequently, a sample of one or
several days is used to represent the true intake (Willett, 1990). The effect of this sampling is to increase
artifically the standard deviation, i.e., to broaden the tails of the distribution (Willett, 1990). This results in
estimates of intake that are both larger and smaller than the true long-term averages for any subject. Overall,
authorities in nutritional epidemiology (among others see Willett, 1990) conclude that "measurements of
dietary intake based on a single or small number of 24-hour recalls per subject may provide a reasonable
(unbiased) estimate of the mean of a group, but the standard deviation will be greatly overestimated."
Assessment of recent dietary intakes can be achieved through dietary records for various periods
(typically 7-day records or 3-day records) or dietary recall (typically 24-hour recalls or 3-day recalls) (among
others see Witschi, 1990). Questions on food frequency in dietary histories can be used to estimate how often
a population consumes fish and shellfish. Research is currently in progress to estimate usual intake
distributions that account for intake data of foods that are not consumed on a daily basis (among others see
Nusser et al. 1996). In 1996, Nusser et al. published a statistical approach to estimating moderate-term (e.g.,
months) patterns of food consumption based on multiple 24-hour dietary recalls obtained from the same
individual.
Sources of error in short-term recalls and records affect all dietary survey methodologies. These
include errors made by the respondent or recorder of dietary information as well as the interviewer or reviewer.
Information used to calculate the intake of the chemical of interest is another source of error. The detection
limit of the analyte, the frequency of zero and trace values, and how such values are managed can statistically
influence the accuracy of the mean mercury concentration for a fish species. The third source of error in
dietary assessments is the data base used to calculate intakes of the chemical from the food consumed, for
example the data may no longer reflect current concentrations of the chemical in foods.
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The ability of the subject to remember the food consumed and in what quantities it was consumed is
central to these methods (among many others see Witschi, 1990). In an analysis of data from the National
Health and Nutrition Evaluation Survey (NHANES), the largest source of error was uncertainty of subjects
about foods consumed on the recall day (Youland and Engle, 1976). Fish consumption appears to be more
accurately remembered than most other food groups. Karvetti and Knuts (1985) observed the actual intake
of 140 subjects and later interviewed them by 24-hour recall. They found that fish was omitted from the
dietary recall less than 5% of the time and erroneously recalled approximately 7% of the time. The validity
of 24-hour recalls for fish consumption was greater than all other food groups. Interviewer and reviewer enors
can be reasonably predicted to be consistent for a given survey and unlikely to affect reporting offish
consumption selectively.
4.1.1.1 Estimates of Fish Intake for Populations
Data on fish consumption have been calculated typically as either "per capita" or "per user". The
former term is obtained by dividing the supply of fish across an entire population to establish a "per capita"
consumption rate. The latter term divides the supply of fish across only the portion of the population that
consumes fish; i.e., "per user" rates of consumption.
Survey methods can broadly be classified into longitudinal methods or cross-sectional surveys.
Typically long-term or longitudinal estimates of intake can be used to reflect patterns for individuals (e.g.,
dietary histories); or longitudinal estimates of moderate duration (e.g., month-long periods) for individuals or
groups. Cross-sectional data are used to give a "snap shot" in time and are typically used to provide
information on the distribution of intakes for groups within the population of interest. Cross-sectional data
typically are for 24-hour or 3-day sampling periods and consist of recall of foods consumed in response to
questioning by a trained interviewer, or they may be taken from written records of foods consumed.
During the past decade, reviewers of dietary survey methodology (for example, the Food and Nutrition
Board of the National Research Council/National Academy of Sciences; the Life Sciences Research Office
of the Federation of American Societies of Experimental Biology) have evaluated various techniques with
regard to their suitability for estimating exposure to contaminants and intake of nutrients. The Food and
Nutrition Board of the National Research Council/National Academy of Sciences in their 1986 publication on
Nutrient Adequacy Assessment Using Food Consumption Surveys noted that dietary intake of an individual
is not constant from day to day, but varies on a daily basis both in amount and in type of foods eaten
(intraindividual variation). Variations between persons in their usual food intake averaged over time is referred
to as interindividual variation. Among North American populations, the intraindividual variation is usually
considered to be as large as or greater than the interindividual variation. Having evaluated a number of data
sets, the Academy's Subcommittee concluded that three days of observation may be more than is required for
the derivation of the distribution of usual intakes.
Major sources of data on dietary intake of fish used in preparing this Report to Congress are the cross-
sectional data from the USDA CSFn conducted from 1989 through 1995 (CSFII 89-91; CSFII 1994; and
CSFII 1995); on cross-sectional data from the NHANES HI conducted between 1988 and 1994; and the
longer-term data on fish consumption based on recorded fish consumption for various numbers of one-month
periods of time during the years 1973-1974 by the National Purchase Diary (NPD 73-74) conducted by the
Market Research Corporation. Longer-term data on fish consumption has also been obtained from questions
on frequency of fish consumption that were included in the NHANES in survey and in CSFII 1994 and CSFII
1995.
Identifying differences in fish consumption rates for population groups can be achieved through
analysis of dietary survey data for the general U.S. population and specified subpopulations; e.g., some tribes
of Native Americans including Alaskan tribes, and recreational anglers. The USDA has conducted a series
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of nationally-based dietary surveys including the 1977-1978 Nationwide Food Consumption Survey and the
Continuing Surveys of Food Intake by Individuals over the period 1989 through 1991 (CSFn 89-91, CSFn
1994, and CSFn 1995), as well as the National Center for Health Statistics stratified population based
examination survey conducted between 1988 and 1994 (NHANES HI). Analyses of fish consumption patterns
among the general U.S. population are described below.
4.1.1.2 Estimates of Month-Long Fish and Shellfish Consumption from Cross-sectional Data
The adverse developmental effects of methylmercury ingestion are closely associated with the
cumulative quantity of methylmercury consumed. The period of development that is critical to the expression
of adverse developmental effects is not known with precision. In humans, the critical exposure period is
thought to be comparatively short-term based on the methylmercury poisoning outbreak in Iraq and various
case reports of in utero methylmercury poisoning (see the Human Health and Risk Characterization Volumes
for additional information). Consequently, it is important to be able to predict moderate-term exposures from
cross-sectional data on methylmercury exposure.
Estimates of a single day's exposure to methylmercury can be calculated from 24-hour recall data.
The quantity of fish/shellfish (portion size) and species of fish/shellfish consumed by an individual over a day
can be used to calculate daily intake offish/shellfish. The 24-hour recall data describe portion size and species
of fish consumed. By including the amount of mercury present in this amount of fish, an estimate of mercury
ingestion can be made. This provides the distribution of mercury intakes for a 24-hour or 1-day period.
Dividing total mercury intake per day by the person's body weight permits calculation of ug Hg/kgbw/day.
Ranking these estimates by increasing quantity permits identification of various percentiles; e.g., 50th, 90th,
95th, etc. These rankings are the basis for "per user" percentiles.
The projection of daily dietary exposure to methylmercury (i.e., pg/kgiw/day) to exposure for a
moderate period of time (e.g., months) has been a well-recognized complication of using dietary data. If
multiple 24-hour recall data for an individual are available, Nusser et al. (1996) have described a statistical
method for projecting moderate-term dietary intakes. Publication of this methodology is comparatively recent
and the computer software/hardware requirements for these statistical analyses are somewhat complex.
Consequently, another approach for projecting month-long fish/shellfish consumption and methylmercury
exposures was needed.
The number of days per month that an individual consumes methylmercury from diet can be estimated
from data on frequency of fish/shellfish consumption. The NHANES DI included questions on how often per
day/week/month, over the past 12-months, an individual consumed fish and shellfish. These data are described
below (Section 4.1.2.2) for persons 12 years of age and older. Children under 12 years-of-age were not part
of the respondents in NHANES ffl who were asked about frequency of fish and shellfish consumption.
Accordingly, the authors of this report have made the simplifying assumption that the frequency of fish
consumption for adults from the same ethnic, racial, and economic groups can be applied to estimates of fish
and shellfish intake for children. Estimates of mercury exposure based on a single day's intake (ug/kgfrw/day)
specific for individual child survey participants were available from the 24-hour recall data in NHANES HI.
These data and the adult's frequency of fish consumption data were used to estimate month-long projections
of methylmercury exposures for children.
4.1.1.3 1973 and 1974 National Purchase Diary Data
The National Purchase Diary 1973-74 (NPD 73-74) data are based on a sample of 7,662 families
(25,165 individuals) out of 9,590 families sampled between September 1973 and August 1974 (SRI
International Contract Report to U.S. EPA, 1980; Rupp et al., 1980). Available reports are not entirely clear
on how the subsample of 7,662 was chosen. Fish consumption was based on questionnaires completed by the
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female head of the household in which she recorded the date of any meal containing fish, the type of fish
(species), the packaging of the fish (canned, frozen, fresh, dried, or smoked, or eaten out), whether fresh fish
was recreationally caught or commercially purchased, the amount of fish prepared for the meal, the number
of servings consumed by each family member and any guests, and the amount of fish not consumed during the
meal. Meals eaten both at home and away from home were recorded. Ninety-four percent of the respondents
reported consuming seafood during the sampling period.
Use of these data to estimate intake of fish or mercury on a body weight basis is limited by the
following data gaps:
1. This survey did not include data on the quantity of fish represented by a serving and
information to calculate actual fish consumption from entries described as breaded fish or fish
mixed with other ingredients. Portion size was estimated by using average portion size for
seafood from the USD A Handbook #11, Table 10, page 40-41. The average serving sizes
from this USDA source are shown in Table 4-1.
Table 4-1
Average Serving Size (gms) for Seafood from
USDA Handbook #11 Used to Calculate
Fish Intake by FDA (1978)
Age Group
(years)
0-1
1-5
6-11
12-17
18-54
55-75
Over 75
Male
Subjects
(gms)
20
66
95
131
158
159
180
Female
Subjects
(gms)
20
66
95
100
125
130
139
There may have been systematic under-recording of fish intake as it was noted that typical
intakes declined 30% between the first survey period and the last survey period among
persons who completed four survey diaries (Crispin-Smith et al., 1985).
There have been changes in the quantities and types offish consumed between 1973-1974
and present. The USDA (Putnam, 1991) indicated that, on average, fish consumption
increased 27% between 1970 to 1974 and 1990. This increase is also noted by the National
Academy of Sciences in Seafood Safety (1991). Whether or not this increase applies to the
highest percentiles of fish consumption (e.g., 95th or 99th percentile) was not described in
the USDA publication.
Changes in the types of fish consumed have been noted. For example, Heuter et al. (1995)
noted that there is currently a much greater U.S. consumption of shark compared to past
decades.
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4. Although the NPD data with the sample weights were used to project these data to the general
U.S. population (SRI International under U.S. EPA Contract 68-01 -3887), in 1980, U.S. EPA
was subsequently informed that the sample weights were not longer available. Consequently,
additional analyses with these data, in a manner than can be projected to the general
population, no longer appear to be possible.
5. Body weights of the individuals surveyed do not appear in published materials. If body
weights of the individuals participating in this survey were recorded these data do not appear
to have been used in subsequent analyses.
Data on fish consumption from the NPD 73-74 survey have been published by Rupp et al. (1980) and
analyzed by U.S. EPA's contractor SRI International (1980). These data indicate that when a month-long
survey period is used, 94% of the surveyed population consumed fish. The species of fish most commonly
consumed are shown in Table 4-2.
Table 4-2
Fish Species and Number of Persons Using the Species of Fish.
(Adapted from Rupp et al., 1980)
Category
Number of Individuals Consuming Fish Based
on 24,652 Replies*
Tuna, light
Shrimp
Flounders
Not reported (or identified)
Perch (Marine)
Salmon
Clams
Cod
Pollock
16,817
5,808
3,327
3,117
2,519
2,454
2,242
1,492
1,466
* More than one species of fish may be eaten by an individual.
Rupp et al. (1980) also estimated quantities of fish and shellfish consumed by teenagers aged 12-18
years and by adults aged 18 to 98 years. These data are shown in Table 4-3. The distribution of fish
consumption for age groups that included women of child-bearing ages are shown in Table 4-4.
Table 4-3
Fish Consumption from the NPD 1973-1974 Survey
(Modified from Rupp et al., 1980)
Age Group
Teenagers Aged
12-18 Years
Adults Aged 18
to 98 Years
50th Percentile
1.88 kg/year
2.66 kg/year
90th Percentile
8.66 kg/year
14.53 kg/year
99th Percentile
25.03 kg/year
or 69 grams/day
40.93 kg/year
or 112 grams/day
Maximum
62. 12 kg/year
167.20 kg/year
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Table 4-4
Distribution of Fish Consumption for Females by Age*
Consumption Category (gins/day) (from SRI, 1980)
Age (years)
10-19
20-29
30-39
40-49
47.6-60.0
0.2
0.9
1.9
3.4
60.1-122.5
0.4
0.9
1.7
2.1
Over 122.5
0.0
0.0
0.1
0.2
* The percentage of females in an age bracket who consume, on average, a specified amount (grams) of fish per day.
The calculations in this table were based upon the respondents to the NPD survey who consumed fish in the month of
the survey. The NPD Research estimates that these respondents represent, on a weighted basis, 94.0% of the population
of U.S. residents (from Table 6, SRI Report, 1980).
4.1.1.4 Nationwide Food Consumption Survey of 1977-78
Fish consumption is not evenly divided across the U.S. population. Analysis of patterns of fish
consumption have been performed on data obtained from dietary surveys of nationally representative
populations. For example, Crochetti and Guthrie (1982) analyzed the food consumption patterns of persons
who participated in the Nationwide Food Consumption Survey of 1977-78. Populations specifically excluded
from this analysis were children under four years of age, pregnant and nursing women, vegetarians, individuals
categorized by race as "other" (i.e., not "white" and not "black"), individuals not related to other members of
the household in which they lived, and individuals with incomplete records. After these exclusions, the study
population consisted on 24,085 individual dietary records for a 3-day period.
Persons reporting consumption offish, shellfish, and seafood at least once in their 3-day dietary record
were categorized as fish consumers. Combinations offish, shellfish, or seafood with vegetables and/or starches
(e.g., rice, pasta) or fish sandwiches were categorized as consumers of fish "combinations". Among the overall
population, 25.0% of respondents reported consumption offish with an additional 9.6% reporting consumption
of fish "combinations" in the 3-day period for a total of 34.6% reporting consumption of fish and/or fish
combinations. Frequency of consumption was comparable for male and female respondents with 24.1% of
men and 25.7% of women reporting consumption of fish in their 3-day dietary records. Fish "combinations"
were reported as dietary items by 11.2% of women and 9.9% of men. Both these food categories were
consumed typically as mid-day and evening meals, rather than as breakfast or as snacks. For persons who
listed fish in their 3-day dietary records, 89.7% listed fish in one meal only with 10.1% of respondents
consuming fish in two meals and 0.1 % consuming fish in three meals. For dishes that combined fish and other
foods (i.e., fish "combinations"), among persons who reported eating fish combinations, 93.4% reported this
food in one meal only with 6.5% of individuals consuming two meals containing fish "combinations."
There appears to be little difference between men and women in their likelihood of consuming fish
based on patterns observed in this national survey (Crochetti and Guthrie, 1982). Based on this analysis,
allocation of fish consumption on a "per capita" basis does not adequately reflect the fish consumption patterns
of the general population of the United States. While "per capita" estimates resulted in an overestimate of fish
consumption for the approximately 65% of the U.S. population who did not report consuming fish, these types
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of estimates by their nature substantially underestimated fish consumption rates by persons who consume fish.
This pattern of underestimation is important in an assessment of impact of infrequently consumed foods such
as fish.
4.1.1.5 CSFII1989-1991
The second set of nation-wide data (CSFII89-91) are presented in Table 4-5, including an age/gender
analysis of the fish-consuming population. Based on analysis of 11,706 respondents who supph'ed 3-days of
dietary record in the CSFII of 1989-1991, the frequency of fish consumption within the 3-day period was
determined. Analyses of these dietary records indicate that 30.9% of respondents consumed fish, either alone
or as part of a dish that contained fish. Most respondents earing fish consumed one fish meal within the 3-day
period. Two percent (2%) of respondents reported consuming fish two or more times during the 3-day period,
and 0.5% of these fish-eating respondents reported fish consumption three or more times during the 3-day
study period. Among persons who reported eating fish within the 3-day period of the survey, 44.1 % reported
eating marine finfish (other than or in addition to tuna, shark, barracuda, and swordfish). Marine finfish were
more frequently consumed than freshwater fish. Of the 1593 people who reported eating finfish, 492 (30.9%)
identified these as freshwater fish.
Table 4-5
CSFII 89-91 Data
Gender
Aged 14 Years
or Younger
Aged 15 through
44 Years
Aged 45 Years
or Older
Total for AH Age
Groups
Number of Individuals With 3 Days of Dietary Records
Males
Females
Total
1497(51.7%)
1396(48.3%)
2893 (24.7%)
2131 (42.9%)
2837(57.1%)
4968 (42.4%)
1537(40.0%)
2308 (60.0%)
3845 (32.8%)
5,165(44.1%)
6,541 (55.9%)
11,706
Respondents Reporting Consumption of All Fish and Shellfish
(Data weighted to be representative of the U.S. population.)
Males
Females
Total
380 (52.8%)
340 (47.2%)
720(19.9%)
646 (42.8%)
864 (57.2%)
1510(41.8%)
556 (39.3%)
828 (58.5%)
1415(39.2%)
1582 (43.8%)
2032 (56.2%)
3614 (30.9%)
4.1.1.6 CSFII 1994 and CSFH 1995
Analyses in 1994 were based on 5296 respondents on day 1 and 5293 respondents on day 2. A change
in survey methods resulted in food consumption data being collected for two days rather than for three days
as in the 1989-91 survey. Dietary records included fish or shellfish for 598 individuals on day 1 and 596
individuals for day 2. These days were not necessarily sequential. Fish/shellfish consumption by age and
gender categories for CSFH 1994 and CSFD 1995 are shown in Tables 4-6 and 4-7, respectively. Overall,
11.3% of respondents reported fish or shellfish consumption. The rate was lower among children under 15
years of age and higher among adults aged 45 years and older.
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Table 4-6
CSFII1994 Data Days 1 and 2
Gender
Aged 14 Years
or Younger
Aged 15
through 44
Aged 15 and
Older
Total for All
Age Groups
Number of Individuals with Dietary Recalls Day 1
Males
Females
Total
% consumption fish
932
942
1874
7.9
852
842
1694
10.9
869
859
1728
15.4
2653
2643
5296
11.3
Respondents Reporting Consumption of All Fish and Shellfish Day 1
Males
Females
Total
65
83
148
90
94
184
138
128
266
293
305
598
Number of Individuals with Dietary Recalls Day 2*
Males
Females
Total
% consumption fish
993
941
1874
8.6
852
840
1692
10.2
868
859
1727
15.1
2653
2640
5293
11.3
Respondents Reporting Consumption of All Fish and Shellfish Day 2
Males
Females
Total
74
88
162
86
87
173
132
129
261
292
304
596
^Methodology changes based on two 24-hour recalls, not necessarily sequential.
To assess whether or not there were seasonal differences in fish and shellfish consumption, the
year was divided into six two-month intervals. Fish intake data was analyzed by season. These values are
shown in Table 4-8.
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Table 4-7
CSFII1995 Data Days 1 and 2
Gender
Males
Females
Total
% Consuming
Fish
Aged 14 Years or
Younger
Aged 15 through
44
Aged 15 and
Older
Total for All Age
Groups
Number of Individuals with Dietary Recalls Day 1
863
808
1,671
7.5
649
635
1,284
11.7
1,067
1,041
2,108
15.4
2,579
2,484
5,063
11.9
Respondents Reporting Consumption of All Fish and Shellfish Day 1
Males
Females
Total
63
63
126
77
73
150
170
155
325
310
291
601
Number of Individuals with Dietary Recalls Day 2
Males
Females
Total
% Consuming
Fish
862
809
1,671
8.8
648
634
1,282
12.9
1,067
1,042
2,109
14.5
2,577
2,485
5,062
12.2
Respondents Reporting Consumption of All Fish and Shellfish Day 2
Males
Females
Total
81
67
148
82
84
166
168
138
306
331
289
620
Table 4-8
Fish Consumption (gms) by Season for Respondents Reporting Seafood Consumption
CFSH 1994 Day 1
Statistics
Mean
Std. Dev*
Minimum
Maximum
Season
Jan/Feb
102
74
2
373
Mar/Apr
92
74
1
488
May/Jun
92
82
2
960
Jul/Aug
107
87
1
903
Sep/Oct
100
77
2 -
413
Nov/Dec
105
77
2
517
4-10
-------
Table 4-8 (continued)
Fish Consumption (grams) by Season for Respondents Reporting Seafood Consumption
CFSII1994 Dayl
Statistics
Season
Jan/Feb
Mar/Apr
May/Jun
Jul/Aug
Sep/Oct
Nov/Dec
Percentiles
5th
10th
25th
Median
75th
90th
95th
Observations
Sum of Weights (OOOs)
14
28
50
86
114
202
293
183
10,197
10
19
51
73
123
173
227
219
11,383
22
28
42
57
118
190
295
210
11,817
21
28
53
85
139
196
272
242
11,506
12
23
49
79
129
204
253
191
9,573
14
24
48
85
165
189
235
163
9,113
* The values in these cells are the weighted standard deviations of the individual observations. Estimates
of the standard errors of the means were not calculated.
4.1.1.7 NHANES IE General Description
The NHANES HI, conducted between 1988 and 1994, used a multistage probability design that
involved selection of primary sampling units, segments (clusters of households) within these units,
households, eligible persons, and finally sample persons. Primary sampling units typically were composed
of a county or group of contiguous counties. Certain subgroups in the population that were of special
interest for nutritional assessment were oversampled: preschool children (six months through five years
old)1, persons 60 through 74 years old, and the poor (persons living in areas defined as poor by the United
States Bureau of the Census for the 1990 census). The U.S. Bureau of the Census selected the NHANES
ffl sample according to rigorous specifications from the National Center for Health Statistics so that the
probability of selection for each person in the sample could be determined.
The statistics presented in the report are population estimates. The findings for each person in the
sample were inflated by the reciprocal of selection probabilities, adjusted to account for persons who were
not examined, and stratified afterward according to race, sex and age, so that the final weighted population
estimates closely approximated the civilian noninstitutionalized population of the United States as
estimated independently by the U.S. Bureau of the Census at the midpoint of the survey, March 1,1990,
Although children are oversampled in the survey design, not all assessmsents were carried out among
young children. For example, 24-hour dietary recall data were obtained for children, however, frequency of fish
consumption information was not obtained.
4-11
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Although NHANES HI was conducted between 1988 and 1994, data on food consumption only
became available in 1996. The survey includes one 24-hour recall obtained by a trained interviewer. This
data base contains 29,973 dietary records including 3864 individuals who consumed fish and shellfish
(Table 4-9). Consumption of fish differed by age. Overall 12.9% of respondents included fish or shellfish
in their 24-hour dietary recall. As observed in CSFTJ 1994, the data among children aged 14 years and
younger was about half the percentages of fish consumption for ages 45 and older (Tables 4-10 and 4-11).
There were questions on frequency offish/shellfish consumption in the CSFII1994 and CSFn 1995 data
bases; however, the specific information obtained excluded canned fish. Consequently, these data were
not used to estimate month-long fish consumption. The 24-hour recall data were analyzed for both
children and adults.
Table 4-9
All Age Groups NHANES
Total
Fish Consumption
% Consumption Fish
Ages 14 and
Younger
12,048
1060
8.8
Ages 15
through 44
Years
10,041
1527
15.2
Ages 45 and
Older
7,884
1274
16.2
Total
29,973
3861
12.9
Table 4-10
NHANES HI Adult Respondents
Gender
Ages 15 to 44
Years
Age 45 Years
and Older
Total for All Age
Groups
Total Respondents
Males
Females
Total
4,620
5,421
10,041
3,783
4,101
7,884
8,403
9,522
29,989
Respondents Reporting Fish Consumption
Males
Females
Total
664
883
1527
605
645
1274
1269
1528
2801
4-12
-------
Table 4-11
NHANES HI Child Respondents
Age Group
1-5 Years
6-11 Years
12-14 Years Female
12-14 Years Male
Total
Total
7595
3217
660
576
12,048
Fish Consumers
626
323
58
53
1060
% Reporting Fish
8.2
10.0
8.8
9.2
8.8
4.1.2 Frequency of Consumption of Fish Based on Surveys of Individuals
4.1.2.1 CSFEI1989-1991
In the USDA 1989 through 1991 Continuing Surveys of Food Intake by Individuals (CSFII 89-
91), food consumption data were obtained from nationally representative samples of individuals. These
surveys included women of child-bearing age 15 through 44 years of age. Data from the CSFn for the
period including 1989 and 1991 were used to calculate fish intake by the general population and women of
child-bearing age. This subpopulation included pregnant women, which are a subpopulation of interest in
the Mercury Study: Report to Congress, because of the potential developmental toxicity to the fetus
accompanying ingestion of methylmercury. Analysis of Vital and Health Statistics data from 1990
indicated that 9.5% of women in this age group can be predicted to be pregnant in a given year. The size
of this population has been estimated using the methodology described in the Addendum to this chapter,
entitled "Estimated National and Regional Populations of United States Women of Child-Bearing Age."
The data described in this section were obtained from nationally representative samples of
individuals and were weighted to reflect the U.S. population using the sampling weights provided by
USDA. The basic survey was designed to provide a multistage stratified area probability sample
representative of the 48 conterminous states. Weighting for the 1989,1990 and 1991 data sets was done in
two stages. In the first phase a fundamental sampling weight (the inverse of the probability of selection)
was computed and the responding weight (the inverse of the probability of selection) was computed for
each responding household. This fundamental sampling weight was then adjusted to account for non-
response at the area segment level. The second phase of computations used the weights produced in the
first phase as the starting point of a reweighing process that used regression techniques to calibrate the
sample to match characteristics thought to be correlated with eating behavior.
The weights used in this analysis reflect CSFn individuals providing intakes for three days.
Weights for the 3-day individual intake sample were constructed separately for each of the three gender-
age groups: males ages 20 and over, females ages 20 and over and persons aged less than 20 years.
Characteristics used in weight construction included day of the week, month of the year, region,
urbanization, income as a percent of poverty, food stamp use, home ownership, household composition,
race, ethnicity and age of the individual. The individual's employment status for the previous week was
used for persons ages 20 and older, and the employment status of the female head of household was used
for individuals less than 20 years of age. The end result of this dual weighting process was to provide
consumption estimates which are representative of the U.S. population.
4-13
-------
Respondents were drawn from stratified area probability samples of noninstitutionalized U.S.
households. Survey respondents were surveyed across all four seasons of the year, and data were obtained
across all seven days of the week. The dietary assessment methodology consisted of assessment of three
consecutive days of food intake, measured through one 24-hour-recall and two 1 -day food records. For
this analysis, the sample was limited to those individuals who provided records or recalls of three days of
dietary intake.
For purposes of interpretability, it should be noted that assessment of fish consumption patterns by
recall/record assessment methods will probably differ from assessments based on food frequency methods
(See Section 4.1.2.3, below). In order to be designated a consumer or "user" of fish for purposes of the
present analysis, an individual would need to have reported consumption of one or more fish/shellfish
products at some time during the three days when dietary intake was assessed. Since fish is not a
frequently consumed food for the majority of individuals, this dietary assessment method will likely
underestimate the extent offish consumption, because some individuals who normally consume fish will
be missed if they did not consume fish during the three days of assessment. In contrast, such users would
be picked up by a food frequency questionnaire. The recall/record dietary assessment method does have
the advantage, however, of providing more precise estimates of the quantities of fish consumed that would
be obtained with a food frequency record.
The information that follows comes from the CSFH 1989-1991 and was provided under contract to
U.S. EPA by Dr. Pamela Raines of the Department of Nutrition of the University of North Carolina School
of Public Health. Data are presented for following groups of individuals surveyed by USDA in the CSFII:
data for the total population, data grouped by gender, and for data grouped by age-gender categories for the
age groups 14 years or younger, 15 through 44 years, and 45 years and older (Table 4-5).
Fish consumption was defined to reflect consumption of approximately 250 individual "Fish only"
food codes and approximately 165 "Mixed dish-fish" food codes present in the 1994 version of the USDA
food composition tables. The USDA maintains a data base (called the "Recipe File") that describes all
food ingredients that are part of a particular food. Through consultation with Dr. Betty Perloff, an USDA
expert in the USDA recipe file, and Dr. Jacob Exler, an USDA expert in food composition, the USDA
recipe file was searched for food codes containing fish or shellfish. The recipe was then scanned to
determine fish codes that were present in the recipe reported as consumed by the survey respondent. The
percent of the recipe that was fish by weight was determined by dividing the weight of the fish/shellfish in
the dish by the total weight of the dish.
As with most dietary assessment studies, multiple days of intake were averaged to reflect usual
dietary intake better. Intakes reported over the three-day period were summed and then divided by three to
provide consumption estimates on a per person, per day basis.
Fish consumption was defined within the following categories.
1. Fish and Shellfish, all types reflected consumption of any fish food code.
2. Marine Finfish, included fish not further specified (e.g., tuna) and processed fish sticks, as
well as anchovy, cod, croaker, eel, flounder, haddock, hake, herring, mackerel, mullet,
ocean perch, pompano, porgy, ray, salmon, sardines, sea bass, skate, smelt, sturgeon,
whiting.
3. Marine Shellfish included abalone, clams, crab, crayfish, lobster, mussels, oysters,
scallops, shrimp and snails.
4. Tuna, contained only tuna.
5. Shark, Barracuda, and Swordfish contained just these three species of fish.
6. Freshwater Fish contained carp, catfish, perch, pike, trout and bass.
4-14
-------
The analysis was stratified to reflect "per capita" (Table 4-12), as well as "per user" (Table 4-13),
consumption patterns. A "consumer" of Fish and Shellfish, all types was one who consumed any of the
included fish only or mixed-fish dish foods. A Marine Finfish consumer was one who consumed any of
the species of fish included within the marine finfish category, and so on for each category. The percent of
the population or subpopulation consuming fish was listed for the entire population, as well as gender
specific values, and age-gender category specific values.
Table 4-12
Consumption of Fish and Shellfish (gins/day), and Self-Reported Body Weight (kg)
in Respondents of the 1989-1991 CSFH Survey.
"Per Capita" Data for All Survey Respondents
(Data are weighted to be representative of the U.S. population.)
Gender
Males
Females
Aged 14 Years or
Younger
Mean
9
8
SD
20
18
kfo.
26
24
Aged 15 through
44 Years
Mean
19
14
SD
35
28
k&.
73
63
Aged 45 Years or
Older
Mean
20
18
SD
36
30
Kfe.
90
67
Total
Mean
17
14
SD
33
27
kg*.
68
58
Table 4-13
Consumption of Fish and Shellfish (gms/day), and
Self-Reported Body Weight (kg) in Respondents of the 1989-1991 CSFII Survey
(Data for "Users" Only. Data are weighted to be representative of the U.S. population.)
Gender
Males
Females
Aged 14 Years or
Younger
Mean
32
29
SD
27
24
kg,.
28
24
Aged 15 through
44 Years
Mean
54
41
SD
39
35
kfo.
80
63
Aged 45 Years or
Older
Mean
51
42
SD
42
34
K&,.
83
68
Total
Mean
49
40
SD
39
33
kfo.
59
54
Consumption of fish-only and mixed-fish-dishes was summed across the three available days of
dietary intake data. This sum was then divided by three to create average per day fish consumpdon figures.
In the tables that describe fish intake, information is presented on sample size, percent of the population
who consumed any product within the specified fish category, the mean grams consumed per day and the
mean grams consumed per kilogram body weight (based on self-reported body weights), standard
deviation, minimum, maximum, and the population intake levels at the 5th, 25th, 50th (median), 75th, and
95th percentiles of the intake distribution for each age-gender category. The means and standard
deviations were determined using a SAS program. Survey sample weights were applied. Analysis with
SAS does not take design effects into account, so the estimates of variance may differ from those obtained
if SUDAAN or such packages had been used. It should be noted, however, that the point estimates of
consumption (grams per consumer per day, grams per consumer per kilogram of body weight) will be
exactly the same between the two statistical analysis packages. Thus, the point estimates rep.orted are
accurate and appropriate for interpretation on a national level.
4-15
-------
Data were obtained for 11,706 individuals reporting 3-days of diet in the 1989-1991 CSFII survey.
Analyses were based on data weighted through statistical procedures (as described previously) to be
representative of the U.S. population. The total group of respondents reporting consumption of finfish
and/or shellfish during the 3-day period were grouped as a subpopulation who consumed fish, as can be
observed in Table 4-13. Fish and shellfish (total fish consumption) were reported to be eaten by 3614
persons (30.9%) of the 11,706 of the survey respondents (see Tables 4-12 and 4-13). The subpopulation
considered to be of greatest interest in this Mercury Study: Report to Congress were women of child-
bearing age (15 through 44 year-old females). Among this group of women ages 15 through 44 years, 864
women of the 2837 surveyed (30.5%) reported consuming fish (see Tables 4-12 and 4-13). Within this
group, 334 women reported consumption of finfish during the 3-day survey period.
Consumption of fish and shellfish varied by species of fish. Overall, marine finfish (not including
tuna, swordfish, barracuda, and shark) and tuna were consumed by more individuals and in greater
quantity than were shellfish. Tuna fish was the most frequently consumed fish product, and separate tables
are provided that identify quantity of tuna fish consumed. Two other categories of finfish were identified:
freshwater fish and a category comprised of swordfish, barracuda, and shark. Freshwater fish were of
interest because U.S. EPA's analysis of the fate and transport of ambient, anthropogenic mercury emissions
from sources of concern in this report indicates that fish may bioaccumulate emitted mercury. Swordfish,
barracuda, and shark were also identified as a separate category. These are predatory, highly migratory
species that spend much of their lives at the high end of marine food web. These fish are large and
accumulate higher concentrations of mercury than do lower trophic level, smaller fish.
4.1.2.2 Estimated Frequency of Fish/shellfish Consumption Based on Food Frequency Questions
in CSFH 1994 and NHANES ffl
Both surveys included questions on frequency of consumption of fish and shellfish. The specific
wording of the questions are shown in the box. The wording of CSFII 1994 separated canned fish from
fish making it difficult to provide an overall estimate of fish consumption because no separate question
addressed frequency of consumption of canned fish. The CSFII survey also provided a separate question
on whether of not any of the fish the respondent ate was caught by the respondent or someone known to
the respondent. Among those respondents who ate non-canned fish during the past 12-month period
(84.1 % of respondents), 37.5% indicated that they had consumed fish caught by themselves or a person
known to them. Shellfish were reported to have been consumed by 62.2% of respondents during the past
12-month period.
4-16
-------
Fish Consumption Survey Questions
CFSI11994
During the past 12 months, that is, since last (NAME OF MONTH), (have you/has NAME) eaten any
(FOOD) in any form?
Yes No
Shellfish 1 2
Fish, other than shellfish or canned fish 1 2
IF YES: Was any of the fish you ate caught by you or
someone you know? 1 2
NHANES III
N2. MAIN DISHES, MEAT, FISH, CHICKEN, AND EGGS
Times Day
g. Shrimp, clams, oysters,
crabs, and lobster per 1oD
Week Month Never or DK
2nW 3oM 4oN or - 9oDK
h. Fish including fillets, fish sticks
fish sandwiches, and tuna fish
.per
1oD 2nW
3oM 4oN
or
9nDK
In the CSFII1994 survey, subjects who consumed fish other than shellfish or canned fish were to
select the answer "yes." Because canned fish (e.g., tuna, sardines) represent major food items, a portion of
the fish consumers would indicate they were nonconsumers if they ate canned fish only. Consequently,
using the results from the CSFII 1994 question would underestimate the frequency of consumption offish.
NHANES III included two questions on fish and shellfish consumption as part of the household
interview portion of the survey. The specific format and wording are shown below. Questions N2g and
N2h addressed shrimp/shellfish and fish separately. Respondents were asked to indicate their frequency of
consumption: never, or how often daily, weekly, or monthly they consumed shrimp/shellfish (g) or fish (h).
Analyses of data from these questions provided the estimates of frequency of fish and shellfish
consumption shown in Table 4-14.
Table 4-14
Frequency of Fish/Shellfish Ingestion and Percent of Respondents*
(NHANES in, Food Frequency Questionnaire, Weighted Data)
Number of times
per month
0
1 or more
2 or more
4 or more
8 or more
12 or more
24 or more
30 or more
AU Adults
12
88
79
58
23
13
3
1
Women Aged
15 44 Years
14
86
78
56
25
12
3
2
Men Aged
1544 Years
11
89
81
58
29
14
3
2
Women Aged 45
Years and Older
11
89
80
61
30
15
2
1
Men Aged 45
Years and Older
9
91
83
63
31
14
3
2
*Adult subjects only. Food frequency data were not collected for children ages 11 and younger.
4-17
-------
Frequency of fish and shellfish consumption data have also been calculated by ethnic/racial
grouping. The groups were: Non-Hispanic whites ("Whites"), Non-Hispanic blacks ("Blacks") and
persons designated as "Other" who included persons of Asian/Pacific Islander ethinicity, Native
Americans, Non-Mexican Hispanics (predominately persons from Puerto Rica and other Carribean
Islands), and additional groups not in the categories "Whites" or "Blacks". Food frequency data for these
groups is shown in Tables 4-15 and 4-16.
Table 4-15a
Frequency of Fish and Shellfish Consumption by Percent among
AH Adults, Both Genders, Weighted Data, NHANES HI*
(Estimated Frequency Per Month)
Frequency per Month
Zero
Once a Month or More
Once a Week or More
Twice a Week or More
Three-Times a Week or More
Approximately Daily (6 Times
Per Week)
White
11.8
88.2
57.1
25.9
11.6
1.9
Black
11.3
88.7
63.5
31.9
15.0
3.3
Other
15.1
84.9
60.3
31.2
22.9
8.9
: Adult subjects only. Food frequency data were not collected for children aged 11 years and younger.
Table 4-15b
Frequency of Fish and Shellfish Consumption by Race/Ethnicity,
Women Aged 15-44 Years, Weighted Data, NHANES HI
(Estimated Frequency Per Month)
Frequency per Month
Zero
Once a Month or More
Once a Week or More
Twice a Week or More
Three-Times a Week or More
Approximately Daily (6 Times
Per Week)
White
13.2
86.8
54.5
22.0
9.5
1.7
Black
10.1
89.9
62.8
31.7
15.9
3.2
Other
19.1
80.9
59.3
35.6
22.7
9.2
4-18
-------
Table 4-16a
Distribution of the Frequency of Fish and Shellfish Consumption by Race/Ethnicity
AH Adults, Both Genders, Weighted Data, NHANES HI
Percentile
50th
75th
90th
95th
Whites
4
8
13
17
Blacks
4
8
13
19
Other
5
10
22
32
Table 4-16b
Distribution of the Frequency of Fish and Shellfish Consumption By Race/Ethnicity
Among Adult Women Aged 15-44, Weighted Data, NHANES III
Percentile
50th
75th
90th
95th
Whites
4
7
11
15
Blacks
4
8
14
20
Other
5
10
23
31
Overall 88% of all adults consume fish and shellfish at least once a month with 58% of adults
consuming fish at least once a week. Between 13% and 23% consume fish/shellfish two or three times per
week. An estimated 3% indicate they consume fish and shellfish six times a week with 1% of all
respondents indicating they eat fish and shellfish daily. Comparatively small differences exist based on
age and gender of adults. Two percent of women of reproductive age and 2% of men in the age range 15
through 44 years indicate they consume fish/shellfish daily.
Among diverse subpopulations those designated as "Other" consume fish and shellfish more
frequently than do individuals in groups identified as "White" and "Black". In the "Other" category 5% of
individuals consume fish and shellfish daily (95th percentile value). Approximately 10% of the
subpopulation of "Whites" consume fish and shellfish three-times or more per week with approximately
23% of persons in the "Other" classification consuming fish and shellfish three-times a week or more.
4.1.2.3 Frequency of Consumption of Various Fish Species by Respondents in NHANES ffi
Grouping of fish and shellfish species by habitat (i.e., freshwater, estuarine, and marine) was done
based on an organization developed by US EPA's Office of Water. Table 4-17 shows which species were
grouped into these three habitat categories.
4-19
-------
Table 4-17
Classification of Fish Species by Habitat*
Marine
Estuarine
Freshwater
Abalone
Barracuda
Clams (92%)
Cod
Crab (54%)
Flatfish (71%)
Haddock
Halibut
Lobster
Mackerel
Mussels
Ocean Perch
Octopus
Pollock
Pompano
Porgy
Salmon (99%)
Sardine
Scallop (99%)
Sea Bass
Seafood (e.g., fish sauce)
Shark
Snapper
Swordfish
Sole
Squid
Tuna
Whitefish
Whiting
Anchovy
Clams (8%)
Crab (46%)
Croaker
Flatfish (29%)
Flounder
Herring
Mullet
Oyster
Perch
Scallop (1%)
Scup
Shrimp
Smelts
Sturgeon
Carp
Catfish
Pike
Salmon (1%)
Trout
^Unprocessed fish (Food Codes 2815061 and 2815065) were not classified by habitat.
Mean consumption rates for only males and females who reported consuming fish/shellfish in the
NHANES HI data set are shown in Table 4-18. Consumption rates for species grouped as marine,
estuarine, and freshwater are shown in Table 4-19. Marine fish are the most frequently consumed followed
by estuarine and freshwater fish. However, when freshwater fish are consumed the portion size is larger
than for marine or estuarine fish. Males consumed larger portions of any of the fish groups than did female
subjects.
4-20
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Table 4-18
Weighted Estimates of Fish and Shellfish Consumed (gms) for Females and Males Aged 15-44
Years Reported in NHANES m (Per User)
Statistic
Mean
Standard Deviation
Minimum
Maximum
Percentiles
5th
10th
25th
Median
75th
90th
95th
Observations
Sum of Weights (OOOs)
Females
103
116
1
117
12
20
37
73
131
228
288
883
1,162
Males
146
149
1
1097
14
28
51
97
185
345
435
645
9,223
Table 4-19
Weighted Estimates for Fish and Shellfish Consumed (gms) by Female and Male Respondents Aged
15 - 44 Years Reported in the NHANES III Survey by Habitat of Species Consumed
Statistic
Mean
Std. Dev
Minimum
Maximum
Marine Fish
Females
86
86
0
957
Males
113
122
0
1004
Estuarine Fish
Females
69
64
0
517
Males
122
131
0
981
Freshwater Fish
Females
158
138
7
740
Males
274
268
14
1097
Percentiles
5th
10th
25th
Median
75th
8
14
37
55
109
1
12
44
84
153
8
9
22
47
101
5
8
29
64
175
13
26
50
127
235
42
42
123
185
313
4-21
-------
Table 4-19 (continued)
Weighted Estimates for Fish and Shellfish Consumed (gms) by Female and Male Respondents Aged
15 - 44 Years Reported in the NHANES III Survey by Habitat of Species Consumed
Statistic
90th
95th
Observations
Sum of Weights (OOOs)
Marine Fish
Females
209
247
519
6.457
Males
204
351
387
5,999
Estuarine Fish
Females
168
202
221
2,653
Males
355
357
198
2,477
Freshwater Fish
Females
330
330
82
516
Males
617
929
60
588
4.1.3 Subpopulations with Potentially Higher Consumption Rates
The purpose of this section is to document fish consumption rates among U.S. subpopulations
thought to have higher rates of fish consumption. These subpopulations include residents of the States of
Alaska and Hawaii, Native American Tribes, Asian/Pacific Island ethnic groups, anglers, and children;
these groups were selected for analysis because of potentially elevated fish consumption rates rather than
because they were thought to have a high innate sensitivity to methylmercury. The presented estimates are
the results of fish consumption surveys conducted on the specific populations. The surveys use several
different techniques and illustrate a broad range of consumption rates among these subpopulations. In
several studies the fish consumption rates of the subpopulations corroborate the high-end (90th percentile
and above) fish consumption estimates of the the nationwide food consumption surveys.
Many of the surveys offish consumption conducted on high-end fish consumers also included
analyses for mercury in hair and blood of the people who were subjects. These data on biological
monitoring provide an additional bases to estimate mercury exposure.
4.1.3.1 Subpopulations Included in Nationally Representative Food Consumption Surveys
Contemporary food consumption surveys designed to be representative of the U.S. population as a
whole included identifiers for ethnically diverse subpopulations. Publicly available data from the
NHANES HI combined three subpopulations of interest with regard to level of fish consumption:
Asian/Pacific origin, Native American origin, and others. By contrast, the CSFII1994 and CSFn 1995
surveys provided separate estimates for identified ethnic subpopulations: white, black, Asian and Pacific
Islander, Native American and Alaskan Native, and other (see Figure 4-1).
The 50th, 90th and 95th percentiles for all survey participants in CSFn 1994 and CSFH 1995 for
"Day 1" and "Day 2" recall data are shown in Table 4-20. The number of 24-hour recall food consumption
reports for each group is noted in the table food note. Data are presented for both "per capita" and "per
user." The subpopulation self-designated as "white" has the smallest intake of fish/shellfish and mercury
at the 50th percentile. "Blacks" have higher levels of intake and Asian and Pacific Islanders have the
highest intake of fish/shellfish. Similar patterns are observed at the 90th and 95th percentile.
If the data are calculated for only those persons who reported consuming fish and shellfish, a
somewhat different pattern emerges. A median intake offish/shellfish is the lowest among Asian and
Pacific Islanders, intermediate among "whites" and highest among "blacks." The number of observations
among Native Americans and Alaska Natives are too small to produce reliable estimates.
4-22
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Figure 4-1
Distribution of Fish Consumption Rates of Various Populations
3SO-
-| Wolfe A Walker'87 Highest Response Group Mean in AK |
-I CRITFC'94 99th %ile Adult
LEGEND - POPULATIONS
GENERAL U.S. POPULATION
NPO 73/74 m
CSFII
RECREATIONAL ANGLERS
PUFFER
FIORE
CONNELY
SUBSISTENCE FISHERS
WOLFE & WALKER A
NATIVE AMERICANS
CRITFC A
TOY. TULAUP W
NOBMAN
EPA '92 Wl TRIBES
Puffer '89 90th %il«
CRITFC "94 95th %ile
-\Toy '95TulalipTribe90th%ile |
Fiore '89 95th %ile
Wl Angtora
j Nobmann "92 AK Tribes Mean |
CRITFC "94 Adult Mean |
Toy '95 Tulalip Tribe Median |
I Rore '89 75th Voile Wl Anglers
NPO 73/74 Adult 90th %ile
Fiore '89 Wl Anglerel4>Xs>[Conrwly '90 NY Anglers Mean|+
1 CSFII Age 15-44 Mean ? anddjl
NPD 73/74 AduH SOth %ile
4-23
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Table 4-20
Consumption of Fish and Shellfish (gins/day) among Ethnically Diverse Groups
(Source: CSFII1994 and CSFII1995)
Ethnic Group
White
50th Percentile
90th Percentile
95th Percentile
Black
50th Percentile
90th Percentile
95th Percentile
Asian and Pacific Islander
50th Percentile
90th Percentile
95th Percentile
Native American and Alaska Native
50th Percentile
90th Percentile
95th Percentile
Other
50th Percentile
90th Percentile
95th Percentile
Fish Consumption (grams/day)
Per Capita*
Zero
24
80
Zero
48
104
Zero
80
127
Zero
Zero
56
Zero
Zero
62
Per User1
72
192
243
82
228
302
62
189
292
Estimate not made because
of small numbers of
respondents.
83
294
327
'Total number of 24-hour food consumption recall reports: White (16,241); Black (2,580); Asian and
Pacific Islander (532); Native American and Alaska Native (166): and Other (1,195).
2 Number of 24-hour food consumption recall reports: White (1,821); Black (329); Asian and Pacific
Islander (155); Native American and Alaska Native (12); and Other (98).
4.1.3.2 Specialized Surveys
During the past decade, data describing the quantities of fish consumed by angler, economically
subsistent, and North American Tribal groups have been published (Tables 4-23 and 4-30).
Subpopulations of particular concern because of exposure patterns are Native Americans, sport anglers, the
urban poor, and children. Data on fish consumption for these groups indicate that exposures for these
subgroups exceed those of the general population of adults. If North American data, including those from
Canada, are considered, mercury exposures from the marine food web (especially if marine mammals are
consumed) exceed limits such as the Tolerable Daily Intake established by Health Canada (Chan, 1997)
and the Acceptable Daily Intake established by the U.S. Food and Drug Administration.
The data cited below on specific Subpopulations are not utilized in this Report as the basis of a
site-specific assessment. In a site-specific assessment the fish consumption rates among a surveyed
4-24
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population would be combined with specific measurements of methylmercury concentrations in the local
fish actually consumed to estimate the human contact rate. Ideally, some follow-up analysis such as
concentrations of mercury in human blood or hair would ensue.
Analytic and survey methods to estimate the fish consumption rates of the respondents are
described for each population. This chapter does not constitute an exhaustive review of the methods
employed. An attempt was made to characterize the population surveyed. Additionally, to characterize the
entire range offish consumption rates in the surveyed populations, the consumption rates of both average
and high-end consumers as well as other specific angler subpopulations (e.g., fish consumption by angler
race or age) are presented.
The sources of consumed fish are also identified in the summaries. Fish consumed by humans can
be derived from many sources; these include self-caught, gift, as well as grocery and restaurant purchases.
Some studies describe only the consumption rates for self-caught fish or freshwater fish, others estimate
total fish consumption, and some delineate each source offish. Humans also consume fish from many
different types of water bodies. When described by the reporting authors, these are also identified.
Assumptions concerning fish consumption made by the study authors are also identified. Humans
generally do not eat the entire fish; however, the species and body parts of fish which are consumed may
be highly variable among angler populations (for example, see Toy et al. 1995). Anglers do not eat their
entire catch, and, some species of fish are typically not eaten by specific angling subpopulations. For
example, Ebert et al. (1993) noted that some types and parts of harvested fish are used as bait, fed to pets
or simply discarded. Study authors account for the differences between catch weight and number in a
variety of different ways. Typically, a consumption factor was applied. These assumptions impact the
author's consumption rate estimates.
Data from angler and indigenous populations are useful in that they corroborate the ranges
identified in the 3-day fish consumption data. The data are not utilized in this Report as the basis of a site-
specific assessment. In a site-specific assessment the fish consumption rates among a surveyed population
would be combined with specific measurements of methylmercury concentrations in the local fish actually
consumed to estimate the human contact rate. Ideally, some follow-up analysis such as concentrations in
human blood or hair would ensue.
4.1.3.3 U.S. Subsistent Populations
Large urban populations include individuals who obtain some of their food by catching and eating
fish from local urban waters. For example, Waller et al. (1996) identified populations living along the lake
shore of Chicago who have ready access to fishing waters of Lake Michigan along the break waters, the
harbors, and in the park lagoons adjacent to Lake Michigan (Table 4-21). Similar situations occur for
many water bodies in urban areas throughout the United States.
4-25
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Table 4-21
Fish Consumption of an Urban "Subsistent" Group
Study
Description of
Group
Fish Consumption Pattern
Notes
Waller et aL
1996
484 pregnant African-
American, urban poor
women
45 of 444 ate no fish; 46 of 444
consumed sport-caught fish; 34
of the women who consumed
sport-caught fish also consumed
store-bought fish.
Types of fish eaten most frequently
in descending order: catfish, perch,
buffalo, silver bass, and whiting.
Others included: bull heads,
sunfish, bluegills, and crappie.
Most catfish consumed was store-
bought. Generally fisheaters did
not consume only one type of fish.
Most of the individuals eating
sport-caught fish also ate wild fowl
and other game (duck, raccoon,
opossum, squirrel, turkey, goose,
and other fowl.
Another group of urban consumers who subsist on fish are persons who are not limited in income,
but individuals who choose to consume a large proportion of their dietary protein from fish because of taste
preference or pursuit of health benefits attributed to fish. For an undetermined number of these
individuals, a particular species of fish may be preferred (e.g., swordfish, sea bass, etc.) and consumed
extensively. Depending on the mercury concentration of the preferred fish, the result of consuming diets
high in fish from one source can be substantially increased exposure to mercury. For example, Knobeloch
et al. (1996) provide cases reports of a family whose blood mercury concentrations increased about ten-
fold following long-term consumption of a particular commercial source of imported fish (Table 4-22).
Likewise, investigation by state authorities in Maine of elevated blood mercury concentrations thought to
result from occupational exposures to mercury, in fact, resulted from frequent consumption of fish (Dr.
Allison Hawkes, 1997). After following physician's advise to reduce fish consumption the blood mercury
levels decreased.
Table 4-22
High Fish Consumption among Urban Subjects: Case Report
Study
Description of
Group
Fish Consumption Pattern
Notes
Knobeloch et
al., 1995
Family consuming
commercially available
fish.
Wisconsin family consumed two
meals/week of seabass imported
from Chile and obtained
commercially which had a mercury
concentration between 0.5 and 0.7
Hg/g. Other fish having low mercury
concentrations (<0.05 ug/g) were
also consumed. The father
consumed an average of 113 g of
fish/day, the mother and son
consumed approximately 75 and 37
grams of fish/day, respectively.
Calculated mercury intakes ranged
from 9 |Jg/day (young child) to 52
Mg/day for the father in the
household.
Family members had blood mercury
levels elevated to 37 and 58 ug/L
and hair mercury values of 10 and 12
Ug/g. Cessation of fish consumption
for 200 days reduced blood mercury
levels to 3 and 5 jig/L.
4-26
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4.1.3.4 U.S. Immigrant Populations
Subpopulations of recent immigrants to the United States retain food patterns characteristic of their
cultures with adaptations based on the available food supply. In the 1980s and 1990s, the proportion of the
U.S. population whose ancestry was Southeast Asian or Caribbean origin increased. The people of rural
Cambodia, Laos, and Vietnam supplemented their agricultural resources by hunting and fishing (Shubat et
al., 1996) and many continue to do so in the United States. Puffer (1981) found that Oriental/Samoan
recreational anglers had fish consumption rates twice the mean value for all anglers in the survey.
Specialized fish advisories for chemical contaminants and outreach programs for Southeast Asian
communities have been developed (Shubat et al., 1996). Increased consumption of purchased frozen fish,
as well as self-caught fish, among Southeast Asians has been reported (Shatenstein et al., 1997). Overall,
these subpopulations have higher fish consumption than does the general U.S. population.
4.1.3.5 U.S. Angling Population Size Estimate and Behaviors
Many citizens catch and consume fish from U.S. waters. The U.S. Fish and Wildlife Service (U.S.
FWS, 1988) reported that in 1985, 26% of the U.S. population fished; over 46 million people in the U.S.
spent time fishing during 1985. Within the U.S. population fishing rates ranged from a low of 17% for the
population in the Middle Atlantic states up to 36% in the West North Central States. These angling
subpopulations included both licensed and non-licensed fishers, hook and line anglers as well as those who
utilized special angling techniques (e.g., bow and arrows, spears or ice-fishing).
U.S. FWS (1988) also noted the harvest and consumption offish from water bodies where fishing
is prohibited. This disregard or ignorance of fish advisories is corroborated in other U.S. angler surveys.
For example, Fiore et al. (1989) noted that 72% of the respondents in a Wisconsin angler survey were
familiar with the State of Wisconsin Fish Consumption Health Advisory, and 57% of the respondents
reported changing their fishing or fish consumption habits based on the advisory. West et al. (1989) noted
that 87.3% of respondents were "aware or generally aware" of Michigan State's fish consumption
advisories. Finally, Connelly et al. (1990) reported that 82% of respondents knew about the New York
State fish health advisories. They also noted a specific example in which angler consumption exceeded an
advisory. The State of New York State recommends the consumption of no more than 12 fish meals/year
of contaminated Lake Ontario fish species; yet, 15% of the anglers, who fished this lake, reported eating
more than 12 fish meals of the contaminated species from the lake in that year.
The extent of the angling population can also be judged from a question included in the USDA's
CSFII for the years 1994 and 1995. In response to a question of whether or not they had eaten fish within
the past 12 months, 84% of individuals indicated they had. Of those who had eaten fish, 38% indicated
that the fish they had eaten was caught by themselves or someone known to the respondent.
4.1.3.6 U.S. Angler Surveys
Summary of Angler Surveys
The results of the fish consumption surveys are compiled in Table 4-23. These results illustrate
the range of fish consumption rates identified in angler consumption surveys. There is a broad range of
fish consumption rates reported for angling populations. The range extends from 2 g/day to greater than
200 g/day. The variability is the result of differences in the study designs and purposes as well as
differences in the populations surveyed.
4-27
-------
Table 4-23
Compilation of the Angler Consumption Studies
Source
Soidat, 1970
Puffer, 1981;
as cited in U.S.
EPA, 1990
Pierce et al.,
1981; as cited in
EPA, 1990
Fioreetal., 1989
Westetal., 1989
Westetal., 1993
Turcotte, 1983
Hovinga et al.,
1992 and 1993
Ebert et al., 1993
Population
Columbia
River
Anglers
Los Angeles
area coastal
anglers
Commence-
ment Bay in
Tacoma, WA
Licensed WI
Anglers
Licensed MI
Anglers
Licensed MI
Anglers
GA anglers
Caucasians
living along
Lake
Michigan
ME anglers
licensed to
fish inland
waters
Percentiie
Mean
Median
90th Percentiie
Ethnic Subpopulation
Medians
African-American
Caucasian
Mexican-American
Oriental/Samoan
50th Percentiie
90th Percentiie
Maximum Reported
Mean
75th Percentiie
95th Percentiie
Mean
75th Percentiie
95th Percentiie
Mean
Mean for Minorities
Maximum Reported
Mean
Child
Teenager
Average Angler
Maximum Angler
Maximum Reported
Mean
50th Percentiie
75th Percentiie
90th Percentiie
95th Percentiie
Daily Fish
Consumption
g/day
2
37
225
24
46
33
71
23
54
381
12
16
37
26
34
63
19
22
>200
15
43
10
23
31
58
132
6
2
6
13
26
Notes
Estimate of average finfish
consumption from river.
Estimates for anglers and
family members who consume
their catch. Consumption rate
includes ingestion of both
finfish and shellfish.
Finfish only
Fish-Eaters, Daily Sportfish
Intake
Fish-Eaters, Total Fish Intake
Daily Sportfish Intake
Daily sportfish intake
Estimates of Freshwater Fish
Intake from the Savannah River
Re-examination of Previously
Identified High-End Fish
Consuming Population
Sportfish Intake
4-28
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Table 4-23 (continued)
Compilation of the Angler Consumption Studies
Source
Courval et al.,
1996
Meredith and
Malvestuto, 1996
Population
Data on
1,950
question-
naires from
Michigan
anglers aged
18-34 years.
29 locations
in Alabama.
Seasonal
estimates of
freshwater
fish
consumption
Percentile
Daily Fish
Consumption
g/day
46% of
respondents
reported eating
sport-caught fish
1-12 times: 20%
reported eating
no sport-caught
fish; 20%
consumed 13 to
24 meals.
Approximately
10% consumed
25 to more than
49 meals/month.
Compared
harvest method
and serving-size
methods of
estimating
consumption.
Harvest method
yielded estimates
of 43 grams/day
fish consumed
from all sites in
Alabama
(number = 563).
Serving-size
method
estimates 46
grams/day from
all sites in
Alabama
(number = 1311)
Consumption
lowest in the
Spring
Notes
Approximately 30% of female
respondents consumed no
sport-caught fish - about double
that of male respondents. In the
1 to 12 meal/month range males
and females about equally
represented. More than 13
meals/month exposure category
had a higher proportion of
males.
Survey to determine
consumption rates of anglers
yielded comparable estimates of
grams/day consumed. However,
serving size method yielded
four-times as many consumers.
4-29
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Table 4-23 (continued)
Compilation of the Angler Consumption Studies
Source
Shubat et al.,
1996
Sekerke et al.,
1994
Population
30 Hmong
anglers
(residents of
St. Paul and
Minneapolis)
fishing St.
Croix or
Mississippi
Rivers. Ages
17-88.
FL residents
receiving
foodstamps
Percentile
Male Mean
Female Mean
Daily Fish
Consumption
g/day
Respondents ate
an average of
3.3±3.0 fish
meals per month
(range 0.5 to
12). Median 2
meals per month
and 8.8 meals at
90th percentile.
60
40
Notes
Consumption of caught fish
only. No information about
size of meals. Species most
frequently canght: crappie,
white bass and walleye, other
bass (largemouth and
smallmouth), northern pike,
trout, bluegill and catfish.
Total Home Fish Consumption
Anglers of the Columbia River, Washington
Soldat (1970) measured fishing activity along the Columbia River during the daylight hours of one
calendar year (1967-68). The average angler in the sampled population made 4.7 fishing trips per year and
caught an average of 1 fish per trip. Assuming 200 g of fish consumed per meal, Soldat estimated an
average of 0.7 fish meals were harvested per trip; this results in an average of 3.3 Columbia River fish
meals/year. The product of 3.3 meals/year and 200 g/meal is 660 g/year; an estimate of 1.8 g/day results.
While not reporting the high-end harvesting or consumption rates, Soldat reported that approximately 15%
of the 1400 anglers interviewed caught 90% of the fish.
Los Angeles, California Anglers
The results of studies from Puffer (1981) and Pierce et al. (1981) are described in U.S. EPA
(1989). Puffer (1981) conducted 1,059 interviews with anglers in the coastal Los Angeles area for an
entire year. Consumption rates were estimated for anglers who ate their catch. These estimates were based
on angling frequency and the assumption of equal fish consumption among all fish-eating family members.
The median consumption rate for fish and shellfish was 37 g/day. The 90th percentile was 224.8 g/day.
Table 4-24 notes the higher consumption rate estimates among Orientals and Samoans.
4-30
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Table 4-24
Median Recreationally Caught Fish Consumption Rate Estimates
by Ethnic Group (Puffer, 1981)
Ethnic Group
African-American
Caucasian
Mexican-American
Oriental/Samoan
Total
Median Consumption Rate
(g/day)
24
46
33
71
37
Anglers of the Commencement Bay Area in Tacoma, Washington
Pierce et al. (1981), as reported in the U.S. EPA 1990 Exposure Factors Handbook, conducted a
total of 509 interviews in the summer and fall around Commencement Bay in Tacoma, Washington. They
assumed that 49% of the live fish weight was edible and that 98% of the total catch was eaten. The
estimated 50th percentile consumption rate was 23 g/day and the estimated 90th percentile consumption
rate 54 g/day. The maximum estimated consumption rate was 381 g/day based on daily angling.
Anglers of the Savannah River in Georgia
Turcotte (1983) estimated fish consumption from the Savannah River based on total harvest,
population studies and a Georgia fishery survey (Table 4-25). The angler survey data, which included the
number of fishing trips per year as well as the number and weights of fish harvested per trip, were used to
estimate the average consumption rate in the angler population. Several techniques including the use of
the angler survey data were used to estimate the maximum fish consumption in the angler population.
Estimates of average fish consumption for children and teens was also provided.
Table 4-25
Freshwater Fish Consumption Estimates of Turcotte (1983)
Georgia
Subpopulation
Child
Teen-ager
Average Angler
Maximum Angler
Estimated Freshwater Fish
Consumption Rate (g/day)
10
23
31
58
4-31
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Alabama Anglers
Meredith and Malestuto (1996) studied anglers in 29 locations in Alabama to estimate freshwater
fish consumption (Table 4-23). The purpose of their study had been to compare two methods of estimating
fish consumption: The harvest or krill survey compared with the serving-size method of estimating fish
consumption. These two techniques yielded comparable estimates of mean fish intake (43 and 46
gms/person/day, respectively). The serving size method identified 1311 consumers while the harvest
method identified only 563 consumers.
Wisconsin Anglers
Fiore et al. (1989) surveyed the fishing and fish consumption habits of 801 licensed Wisconsin
anglers. The respondents were divided into 2 groups: fish eaters and non-eaters. The fish eaters group
was further subdivided into four groups: those who consumed 0-1.8 kg fish/yr, 1.9-4.5 kg fish/yr, 4.6-
10.9 kg fish/yr and 10.9 < kg fish/yr. Using an assumption of 8 oz. (227 grams) fish consumed/meal, the
authors estimated that the mean number of sport fish meals/year for all respondents (including non-eaters)
was 18. The mean number of other fish meals/year including non-eaters was 24. The total number of fish
meals/year was 41 for fish eaters and non-eaters combined and 42 for fish eaters only. Recreational
anglers were found to consume both commercial fish as well as sport fish. The estimated daily
consumption rates of the eaters-only are presented in Table 4-26.
Table 4-26
Daily Intake of Sportfish and Total Fish for the Fish-consuming Portion
of the Population Studied by Fiore et al. (1989)
Percentile
Mean
75th
95th
Daily Sport-Fish Intake
12g/day
1 6 g/day
37 g/day
Daily Total Fish Intake
26 g/day
34 g/day
63 g/day
Michigan Anglers
West et al. (1989) used a mail survey to conduct a 7-day fish consumption recall study for licensed
Michigan anglers. The respondents numbered 1104, and the response rate was 47.3%. The mean fish
consumption rate for anglers and other fish-eating members of their households was 18.3 g/day, and the
standard deviation was 26.8 g. Because the study was conducted from January through June, an off-season
for some forms of angling in Michigan, higher rates of fish consumption would be expected during the
summer and fall months. A full-year's mean fish consumption rate of 19.2 g/day was estimated from
seasonal data. The mean fish consumption rate for minorities was estimated to be 21.7 g/day. The highest
consumption rates reported were over 200 g/day; this occurred in 0.1% of the population surveyed.
Overall, fish consumption rates increased with angler age and lower education levels. Lower income and
education level groups were found to be the only group which consumed bottom-feeders.
New York State Anglers
Connelly et al. (1990) reported the results of a statewide survey of New York anglers. The 10,314
respondents (62,4% response rate) reported a mean of 20.5 days spent fishing/year. Of the respondents,
4-32
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84% fished the inland waters of New York State, and 42% reported fishing in the Great Lakes. An overall
mean of 45.2 fish meals per year was determined for New York anglers. The authors assumed an average
meal size of 8 oz. (227 g) offish and estimated a yearly consumption rate of 10.1 kg fish (27.7 g fish/day).
Unlike the Michigan angler study (West et al., 1989), the overall mean number offish meals consumed
increased with education level of the angler. Fish consumption also increased with increasing income;
respondents earning more than $50,000/year consumed a mean of 54.3 meals per year, and those with
some post-graduate education consumed a mean of 56.2 meals per year. The highest reported regional
mean consumption rates (58.8 meals/year) occurred in the Suffolk and Nassau Counties of New York
State.
Anglers of Lake Michigan
As part of a larger effort, Hovinga et al. (1992 and 1993) re-examined 115 eaters of Great Lakes
fish and 127 controls, who consumed smaller quantities offish, originally identified in a 1982 effort. Both
more recent (1989) as well as 1982 consumption rates of Great Lakes sportfish were estimated. All of the
participants in the study were Caucasian and resided in 11 communities along Lake Michigan. The
population was divided into eaters (defined as individuals consuming 10.9 kg (30 g/day) or greater) and
controls (defined as individuals consuming no more than 2.72 kg/yr). The consumption rates for the
groups are reported in Table 4-27.
Table 4-27
Fish Consumption Rate Data for Groups Identified in
Hovinga et al. (1992) as Eaters and Controls
Groups
Eaters
Controls
1982
Meals/Year
Mean (Range)
54(24-132)
-
1982 Consumption
Rates (kg/yr)
Mean (Range)
18(11-53)
1989
Meals/Year
Mean (Range)
38 (0-108)
4.1 (0-52)
1989 Consumption
Rates (kg/yr)
Mean (Range)
10 (0-48)
0.73 (0-8.8)
Anglers of Inland Waters in the State of Maine
Ebert et al. (1993) examined freshwater fish consumption rates of 1,612 anglers licensed to fish
the inland (fresh) waters of Maine. They only analyzed fish caught and eaten by the anglers. Anglers were
asked to recall the number, species and average length of fish eaten in the previous year; the actual fish
consumption rates were estimated based on an estimate of edible portion of the fish. The 78% of
respondents who fished in the previous year and 7% who did not fish but did consume freshwater fish were
combined for the analysis. Anglers who practiced ice-fishing as well as fish caught in both standing and
flowing waters were included. Twenty-three percent of the anglers consumed no freshwater fish. If the
authors assumed that the fish were shared evenly among all fish consumers in the angler's family, a mean
consumption rate of 3.7 g/day was estimated for each consumer. Table 4-28 provides the fish consumption
rates for Maine anglers.
4-33
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Table 4-28
Fish Consumption Rates for Maine Anglers
Percentile
Mean
50th (median)
75th
90th
95th
All Anglers
5.0
1.1
4.2
11
21
Fish-consuming
Anglers
6.4
2.0
5.8
13
26
Florida Anglers Who Receive Food Stamps
As part of a larger effort the Florida Department of Environmental Regulation attempted to
identify fish consumption rates of anglers who were thought to consume higher rates of fish. Face-to-face
interviews were conducted at five Florida food stamp distribution centers. The selected food stamp
distribution centers were located in counties either thought to have a high likelihood of subsistence anglers
or where pollutant concentrations in fish were known. Interviews with twenty-five household's primary
seafood preparer were conducted at each center per quarter for an entire year. A total of 500 interviews
was collected. The interviewed were asked to recall fish consumption within the last 7 days. Specifically,
the respondents were asked to recall the species, sources and quantities of fish consumed. Note that the
respondents were only asked to recall fish meals prepared at home (actual consumption rates may have
been higher if the respondents consumed seafood elsewhere) and that the sources of fish were from both
salt and freshwater. The results of the survey conducted by Sekerke et al. (1994) are in Table 4-29.
Table 4-29
Fish Consumption Rates of Florida Anglers Who Receive Food Stamps
1 Respondent
Adult Males
Adult Females
No.
366
596
Average Finfish
Consumption
60 g/day
40 g/day
Average Shellfish II
Consumption |
50 g/day ||
30 g/day 1
4.1.3.7 Indigenous Populations of the United States
The tribes and ethnic groups who comprise the indigenous populations of the United States show
wide variability in fish consumption patterns. Although some tribes, such as the Navajo, consume minimal
amounts of fish as part of their traditional culture, other native groups such as the Eskimos, Indians, and
Aleuts of Alaska, or the tribes of Puget Sound traditionally consume high quantities of fish and fish
products. The U.S. indigenous populations are widely distributed geographically. For example, a U.S.
EPA report (1992b) identified 281 Federal Indian reservations that cover 54 million acres in the United
States. Treaty rights to graze livestock, hunt, and fish are held by native peoples for an additional 100 to
125 million acres. There are an estimated two million American Indians in the United States (U.S. EPA,
4-34
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1992b). Forty-five percent of these two million native people live on or near reservations and trust lands.
High-end fish consuming groups include Alaska natives who number between 85,000 and 86,000 people
(Nobmann et al., 1992).
Fish products consumed by indigenous populations may rely on preparation methods that differ
from ones typically encountered in the diet of the general U.S. population. By way of illustration, food
intake data obtained from Alaskan natives were used to calculate nutrient intakes using a computer and
software program. These computerized databases had been developed by the U.S. Veterans
Administration (VA) for patients in the national Veteran's Administration hospital system. Nobmann et al.
(1992) found they needed to add data for 210 dietary items consumed by Alaskan Natives to the 2400 food
items in the VA files.
In the mid-1990s data on fish consumption by indigenous populations of the United Stales were
reported for Alaska Natives (Nobmann et al., 1992), Wisconsin Tribes (U.S. EPA, 1992), the Columbia
River Tribes (Columbia River Inter-Tribal Fish Commission, 1994) and selected Puget Sound Tribes (Toy
et al. 1995). Findings from these studies can be used to assess differences in fish consumption between
these indigenous groups and the general U.S. population.
Summary of Native American Angler Surveys
Table 4-30 summarizes the reported consumption rates of Native Americans detailed here.
Although not all Native American tribal groups traditionally include fish as part of their diets, groups
living near rivers, lakes, and coastal areas consume a vide variety of fish and shellfish. The highest levels
offish and shellfish consumption are thought to occur among tribal groups living along the Pacific Coast
and in Alaska. Tribal groups in the Great Lakes region also include fish as part of their typical diet. The
data base to estimate quantities of fish consumed has been greatly enhanced over the past five years with
the publication of a number of dietary assessments conducted as part of activities to determine exposure to
chemical contaminants in fish.
Surveys of Native American anglers in the United States indicate an average fish/shellfish
consumption in the rage of 30 to 80 grams per day (U.S. EPA, 1992b; Harnly et al., 1997; Toy et al., 1995)
with 90th percentile consumption of about 150 grams/day or higher (Toy et al., 1995). Inclusion of data
on Alaskan Native Americans results in still higher levels of fish and shellfish intake. For example,
Nobmann et al. (1992) reported mean fish consumption estimates in excess of 100 grams/day.
Table 4-30
Fish Consumption by Native U.S. Populations
Source
Nobmann
etal., 1992
U.S. EPA,
1992b
Population
351 Alaska Native
adults (Eskimos,
Indians, Aleuts)
Wisconsin Tribes 1 1
Native American
Indian Tribes
Percentile
Mean
Mean
Fish-Meals
Consumed or Fish
Consumption (gins)
109 gms of fish and
shellfish per day.
32 gms of fish per day
Notes
-
4-35
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Table 4-30 (continued)
Fish Consumption by Native U.S. Populations
Source
Peterson et
al., 1995
Toy et al.,
1995
Fitzgerald
et al., 1995
Population
323 Chippewa adults
> 1 8 years of age.
Tulalip and Squaxin
Island Tribes. 263
adult subjects.
97 nursing Mohawk
women
Percentile
Mean= 1.7 fish
meals/week.
(1.9 and 1.5 fish
meals/week for male
and for female
respondents,
respectively).
0.26% of males and
0.15% of females
reported eating 3 or
more fish-meals per
week.
50% of respondents
ate one or less fish
meals per week.
21% of respondents
ate three or more fish
meals per week.
2% of respondents ate
fish-meals each day.
50th percentile:
Finfish, 22 gms/day:
total fish consumed.
43 gms/day.
90th percentile:
Finfish, 88 gms/day;
total fish, 156
gms/day.
24.7% ate 1-9 local
fish meals/year during
pregnancy;
10.3% ate >9 local
fish meals/year during
pregnancy;
4 1.2% ate 1-9 local
fish meals/year one
year prior to
pregnancy;
1 5. 4% ate >9 local
fish meals/year one
year prior to
pregnancy;
Fish-Meals
Consumed or Fish
Consumption (gins)
Notes
. .
Report contains
data for
anadromous fish,
pelagic, bottom
and shell fish.
Data are based on
an average body
weight of 70
kg/day.
Study conducted
from 1986-1992
in area where fish
are contaminated
with PCB
4-36
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Table 4-30 (continued)
Fish Consumption by Native U.S. Populations
Source
Centers for
Disease
Control,
1993
Gerstenber
ger et al.,
1997
Population
Miccouskee Indian
Tribes of South
Florida (1993), 2
children and 183
adults completed
dietary questionaires
89 Ojibwa Tribal
members from the
Great Lakes Region
Percentile
Fish-Meals
Consumed or Fish
Consumption (gms)
Local fish: 31% (58
persons) reported eating
fish from Everglades
during previous 6
months. Maximum
daily consumption: 168
grams Median daily
consumption: 3.5 grams
Marine fish: 57% (105
persons) consumed
marine fish during
previous 6 months.
Nonlocal freshwater
fish: 1 individual, 25
grams/day
Local wildlife: 65%
(120 participants)
consumed local game.
35% of respondents ate
Lake Superior fish
Ix/week. 6.7% ate
Lake Superior fish
2x/week.
Consumption of fish
from other lakes:
12.5% ate these
Ix/week
5.7% ate these 2x/week
89 respondents
averaged 29 fish
meals/year (range zero
to 150 fish meals/year)
Notes
Blue gill most
common species
of local fish
consumed.
Largemouth bass
consumed in
greatest quantity
Canned tuna most
commonly
consumed (by all
105 of marine
consumers) and
in the largest
amounts (7.0
grams/day
median level)
Local game
consumed: deer
(57% of
participants),
wildboar(10%),
redbelly turtle
(10%), frog (5%)
and alligator
(3%)
Most frequently
consumed fish
from Lake
Superior: lake
trout (37%),
walleye (27%),
whitefish (27%).
From inland
lakes: Walleye.
Highest fish
consumption in
April, May, and
June
4-37
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Table 4-30 (continued)
Fish Consumption by Native U.S. Populations
Source
Harnly et
al., 1997
Population
Native Americans
living near Clear Lake
California
Percentile
Fish-Meals
Consumed or Fish
Consumption (gms)
Fish-consuming
participants averaged
60 g/day of sportfish
and 24 g/day of
commercial fish.
10% of adults
consumed Hg intakes >
30 jig/day
Notes
Sportfish species:
catfish, perch,
hitch, bass, carp
Commercial fish:
snapper, tuna,
salmon, crab,
shrimp.
Wisconsin Tribes
An U.S. EPA report entitled Tribes at Risk (The Wisconsin Tribes Comparative Risk Project) (US
EPA, 1992) reported an average total daily fish intake for Native Americans living in Wisconsin of
35 gms/day. The average daily intake of locally harvested fish was 31.5 grams.
Peterson et al. (1995) surveyed 323 Chippewa adults over 18 years of age living on the Chippewa
reservation in Wisconsin. The survey was conducted by interview and included questions about season,
species and source of fish consumed. The survey was carried out in May. Fish consumption was found to
be seasonal with the highest fish consumption occurring in April and May. Fish species typically
consumed were walleye and northern pike, muskellunge and bass. During the months in which the
Chippewa ate the most fish, 50% of respondents reported eating one or fewer fish meals per week, 21 %
reported eating three or more fish meals per week, and 2% reported daily fish consumption. The mean
number of fish meals per week during the peak consumption period was 1.7 meals; this is approximately
42% higher than the 1.2 fish meals per week that respondents reported as their usual fish consumption.
Higher levels of fish consumption were reported by males (1.9 meals per week) than by females (1.5 meals
per week). Among male respondents 0.26% ate 3 or more fish meals per week, whereas 0.15% of female
respondents ate 3 or more meals of fish per week. Unemployed persons typically had higher fish
consumption rates.
Columbia River Tribes
The Columbia River Inter-Tribal Fish Commission (1994) estimated fish consumption rates based
on interviews with 513 adult tribal members of four tribes inhabiting the Columbia River Basin (see Tables
4-31 and 4-32). The participants had been selected from patient registration lists provided by the Indian
Health Service. Data on fish consumption by 204 children under 5 years of age were obtained by
interviewing the adults.
Fish were consumed by over 90% of the population with only 9% of the respondents reporting no
fish consumption. The average daily consumption rate during the two highest intake months was 108
grams/day, and the daily consumption rate during the two highest and lowest intake months were 108
g/day and 31 g/day, respectively. Members who were aged 60 years and older had an average daily
consumption rate of 74 grams/day. During the past two decades, a decrease in fish consumption was
4-38
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generally noted among respondents in this survey. The maximum daily consumption rate for fish reported
for this group was approximately 970 grams/day.
Table 4-31
Fish Consumption by Columbia River Tribes
(Columbia River Inter-Tribal Commission, 1994)
Subpopulation
Total Adult Population, aged 1 8 years and older
Children, aged 5 years and younger
Adult Females
Adult Males
Mean Daily Fish Consumption (g/day)
59
20
56
63
Table 4-32
Daily Fish Consumption Rates by Adults of Columbia River Tribes
(Columbia River Inter-Tribal Commission, 1994)
Percentile
50th
90th
95th
99th
Amount (g/day)
29-32
97-130
170
389
Tribes ofPuget Sound
A study offish consumption among the Tulalip and Squaxin Island Tribes of Puget Sound was
completed in November 1994 (Toy et al., 1995). The Tulalip and Squaxin Island Tribes live
predominantly on reservations near Puget Sound, Washington. Both tribes rely on commercial fishing as
an important part of tribal income. Subsistence fishing and shell-fishing are significant parts of tribal
members economies and diets.
The study was conducted between February and April in 1994. Fish consumption practices were
assessed by questionnaire and interview using dietary recall methods, food models and a food frequency
questionnaire. The food frequency questionnaire was aimed as identifying seasonal variability. Questions
in the interview included food preparation methods and obtained information on the parts of the fish
consumed. Fish consumed were categorized into anadromous fish (king salmon, sockeye salmon, coho
salmon, chum salmon, pink salmon, steelhead salmon, salmon unidentified and smelt); pelagic fish (cod,
pollock, sable fish, spiny dogfish, rockfish, greenling, herring and perch); bottom fish (halibut,
sole/flounder and sturgeon); and shell fish (manila clams, little clams, horse clams, butter clams, cockles,
oysters, mussels, shrimp, dungeness crab, red rock crab, scallops, squid, sea urchin, sea cucumbers and
moon snails).
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Among consumers of anadromous fish, local waters (i.e., Puget Sound) supplied a mean of 80% of
the fish consumed. Respondents from the Tulalip Tribes purchased a mean of approximately two-thirds of
fish from grocery stores or restaurants, while among the Squaxin Island Tribe, the source of fish was about
50% self-caught and 50% purchased from grocery stores or restaurants. For bottom fish, members of both
tribes caught about half of the fish they consumed. Anadromous fish were much more likely to be
consumed with the skin attached. Most other fish were consumed minus the skin. Approximately 10% of
the respondents consumed parts of the fish other than muscle; i.e., head, bones, eggs.
Data on fish consumption were obtained for 263 members from the Tulalip and Squaxin Island
tribes. The mean consumption rate for women of both tribes was between 10-and-12-times higher than the
default rate of 6.5 grams/day used by some parts of the U.S. government to estimate fish intake. Among
male members of both tribes, the consumption rate was approximately 14-times higher than the default
rate. The 50th percentile consumption rate for finfish for both tribes combined was 32 grams/kg body
weight/day. Male members of the Tulalip and Squaxin Island tribes had average body weights of
189 pounds and 204 pounds, respectively. Female members of the Tulalip and Squaxin Island tribes
weighed on average 166 pounds and 150 pounds, respectively. If an average body weight is assumed to be
70 kg, the daily fish consumption rate for both tribes for adults was 73 grams per day with a 90th
percentile value of 156 grams per day for total fish. Fish consumption data for selected categories of fish
are shown in Table 4-33.
Table 4-33
Fish Consumption (gins/kg bw/day) by the Tulalip and Squaxin Island Tribes
(Toy et al., 1995)
Type of
Fish
Anadromous
Pelagic
Bottom
Shell
Fish
Other
Fish
Total
Finfish
Total
All Fish
5th
Percentile
.0087
.0000
.0000 %
.0000
.0000
.0200
.0495
50th
Percentile
.2281
.0068
.0152
.1795
.0000
.3200
.6081
90th
Percentile
1.2026
.1026
.1095
1.0743
.0489
.1350
2.2267
95th
Percentile
1.9127
.2248
.2408
1.4475
.1488
2.1800
3.2292
Mean
.4600
.0390
.0482
.3701
.0210
.5745
1.0151
SE
.0345
.0046
.0060
.0343
.0029
.0458
.0865
95th
Percent CI
.3925, 0.5275
.0300, 0.0480
.0364, 0.4375
.3027, 0.4375
.0152,0.0268
.4847, 0.6643
.8456, 1.1846
During the survey period, 21 of the 263 tribal members surveyed reported fish consumption rates
greater than three standard deviations from the mean consumption rate. For example, six subjects reported
consumptions of 5.85, 6.26, 9.85,11.0, 22.6 and 11.2 grams of finfish and shell fish/kg body weight/day.
If a 70-kg body weight is assumed these consumption rates correspond to 410, 438, 690, 770 and 1582
grams per day.
4-40
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Mohawk Tribe
A study offish consumption among 97 nursing Mohawk women in rural New York State was
conducted from 1986 to 1992 (Fitzgerald et al., 1995). Fish consumption advisories had been issued in the
area due to polychlorinated biphenyl (PCB) contamination of the local water body. Using food frequency
history and a long-term dietary history, the women were asked about their consumption of locally caught
fish during three specific periods of time: during pregnancy, the year prior to pregnancy, and more than a
year before pregnancy. For comparison, the study also surveyed fish consumption rates among 154
nursing (primarily Caucasian) women from neighboring counties. The socioeconomic status of the women
of the control group were similar to that of the Mohawk women. The fish in these counties had
background PCB concentrations.
The results (Table 4-34) showed that the Mohawk women had a higher prevalence of consuming
locally caught fish than the comparison group in the two intervals assessed prior to the pregnancy; the
prevalence of local fish consumption during pregnancy for the two groups was comparable. A decrease in
local fish consumption rates was also noted over time; these may be related to the issuance of advisories.
Table 4-34
Local Fish Meals Consumed By Time Period for the
Mohawk and Comparison Nursing Mothers (Fitzgerald et al., 1995)
Fish Meals/
Year
0
1-9
10-19
>19
During Pregnancy
Mohawk
64.9%
24.7%
5.2%
5.1%
Control
70.8%
15.6%
4.5%
9.1%
1 Year Before Pregnancy
Mohawk
43.3%
41.2%
4.1%
11.3%
Control
64.3%
20.1%
3.9%
11.7% -
>1 Year Before Pregnancy
Mohawk
20.6%
43.3%
6.2%
29.9%
Control
60.4%
22.7%
5.2%
11.7%
Native Americans near Clear Lake, California
Hamly et al. (1997) found that Native Americans living near Clear Lake, California consumed an
- average of 84 grams of fish/day (60 g/day sport fish plus 24 g/day of commercial fish). Ten percent of
adults reported mercury intakes over 30 ng/day. The most popular species of sportfish were: catfish,
perch, hitch, bass, and carp. Commercial species most commonly eaten were: snapper, tuna, salmon, crab,
and shrimp.
Great Lakes Tribes
Members of the Ojibwa live in the Great Lakes region of the United States and Canada.
Gerstenberger et al. (1997) reported that approximately 35% of the respondents (89 members of the
Ojibwa Tribes) consumed Lake Superior fish at least once a week with 7% of this group consuming Lake
Superior fish at least twice a week. The most commonly consumed Lake Superior-origin fish were lake
trout, walleye, and whitefish. In addition, fish were consumed from inland lakes with 12% of reponsdnets
4-41
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eating inland lake fish once a week and 6% consuming these fish twice a week. Walleye was the most
common species of fish consumed from these inland lake sources.
4.1.4 Summary of Hawaiian Island Fish Consumption Data
The CSFII1989-1991 did not include the Hawaiian Islands. To the knowledge of the authors of
the Mercury Study Report to Congress, data describing fish consumption by the general Hawaiian
population that estimate Island-wide levels of consumption have not been reported. However, reports on
commercial utilization of seafood (Higuchi and Pooley, 1985; Hudgins, 1980) and analysis of
epidemiology data (Wilkens and Hankin, personal communication, 1996) provide a basis to describe
general patterns of consumption. Overall, seafood consumption in Hawaii is much higher than in the
contiguous United States. On a per capita basis, the United States as a whole consumed 5.45 kg and 5.91
kg (12 and 13 pounds) of seafood in 1973 and 1977, respectively (Hudgins, 1980). By contrast Hawaiian
per capita consumption for all fish products was 11.14 kg (24.5 pounds) in 1972 and 8.77 kg (19.3
pounds) in 1974.
The most popular species of fish and shellfish consumed were moderately comparable between
Hawaii and the contiguous 48 states. The methods of food preparation differed, however, with raw fish
being far more commonly consumed in Hawaii. Sampled at the retail trade level the most commonly
purchased fish were: tuna, mahimahi, and shellfish [see Table 4-35 which is based on data in Higuchi and
Pooley (1985)]. A survey of seafood consumption by families was identified. In 1987, the Department of
Business and Economic Development (State of Hawaii, 1987) conducted a survey of 400 residents selected
on a random digit dialing basis of a population representing 80% of total state seafood consumption. All
data were collected in July and August, 1987 and would not reflect any seasonal differences in
fish/shellfish consumption. The respondents were asked to describe seafood consumption by their
families. Shrimp was the most popular seafood with mahimahi or dolphin fish as the second most popular
(Hawaii Seafood, 1988). Reports on fish consumption in Hawaii separate various species of tuna: ahi
(Hawaiian yellowfin tuna, bigeye tuna & albacore tuna), aku (Hawaiian skipjack tuna), and tuna. In 1987,
nearly 66% of the 400 families surveyed had seafood at least once a week and 30% twice a week. Only
4% did not report consuming seafood during the previous week based on a telephone survey.
Wilkens and Hankin (personal communication, 28 February 1996) analyzed fish intake from 1856
control subjects from Oahu who participated in research studies conducted by the Epidemiology Program
of the Cancer Research Center of Hawaii, University of Hawaii at Manoa. These subjects were asked
about consumption over a one-year period prior to the interview. Within this group the most commonly
consumed fish was tuna [canned with tuna species undesignated (70.8 % of subjects reporting
consumption)]; shrimp (47.7% of subjects); tuna (yellowfin fresh designated aku, ahi with 42.2% of
subjects reporting consumption); mahimahi [(or dolphin) with 32.5% of respondents reporting
consumption]; and canned sardines (with 29.1% of subjects reporting consumption).
4-42
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Table 4-35
Species Composition of Hawaii's Retail Seafood Trade 1981 Purchases
Higuchi and Pooley (1985)
Fish/Shellfish
Tuna
Ahi (Hawaiian yellow-
fin, bigeye & albacore)
Billfish (including swordfish)
and shark
Mahimahi and ono (wahoo)
Akule (Hawaiian bigeye scad)
and opelu
Bottom fish
Reef fish
Shellfish
Shrimp
Lobster
Other species
Salmon/trout
Snapper
Frozen filets
Frozen sticks/blocks
Total
Pounds Purchased
11,600,000
(5,400,000)
5,900,000
9,900,000
4,00,000
2,600,000
3,500,000
8,200,000
(4,200,000)
(900,000)
8,300,000
(1,500,000)
(1,800,000)
(2,300,000)
(1,400,000)
54,000,000
Percent of Total Purchases
20.9
11.3
17.7
6.9 -
7.0
5.3
15.5
15.4
100.0
4.1.5 Summary of Alaskan Fish Consumption Data
The CSFII analyses of food intake by the USDA include the 48 contiguous states but do not
include Alaska or Hawaii. A number of investigators have published data on fish consumption in Alaska
by members of native populations (e.g., Inuits, Eskimos) and persons living in isolated surroundings.
These reports focus on nutritional/health benefits of high levels of fish consumption, food habits of native
populations, and/or effects of bioaccumulation of chemicals in the aquatic food web.
4.1.5.1 General Population
After contacting professionals from the Alaskan health departments and representatives of the U.S.
Centers for Disease Control in Anchorage, the authors of this report have not identified general population
data on fish consumption among Alaskan residents who are not part of native population groups,
subsistence fishers/hunters, or persons living in remote sites. Patterns of fish consumption among urban
residents (e.g., Juneau, Nome, Anchorage) appear not to be documented in the published literature.
4-43
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4.1.5.2 Non-urban Alaskan Populations
Native people living in the Arctic rely on traditional or "country" foods for cultural and economic
reasons. The purpose of the current discussion is not to assess the comparative risks and benefits of these
foods. The risks and benefits of these food consumption habits have been compared by many investigators
and health professionals (among others see Wormworth, 1995; Kinloch et al., 1992; Bjerregaard, 1995).
Despite a degree of acculturation in the area of foods, native foods were still eaten frequently by
Alaskan Native peoples based on results of the 1987-1988 survey. Diets that include major quantities of
fish (especially salmon) and sea mammals retain a major place in the lives of Alaskan Native peoples. The
consumption of traditional preparations of salmon and other fish continues; this includes fermented foods
such as salmon heads and eggs, other fish and their eggs, seal, beaver, caribou and whale.
Diets of Native Alaskans differ from the general population and rely more extensively on fish and
marine mammals. These are population groups that are characterized by patterns of food consumption that
reflect availability of locally available foods and include food preparation techniques that differ from those
usually identified in nutrient data bases. For example, Nobmann et al. (1992) surveyed a population of
Alaska Natives that included Eskimos (53%), Indians (34%), and Aleuts (13%). The distribution of study
participants was proportional to the distribution of Alaska Natives reported in the 1980 Census. The 1990
Census identified an overall population of 85,698 persons as Alaska Natives.
Nobmann et al. (1992) indicated that Alaska Natives have traditionally subsisted on fish; marine
mammals; game; a few plants such as seaweed, willow leaves, and sourdock; and berries such as
blueberries and salmonberries rather than on a plant-based diet. In preparing a nutrient analysis of the food
consumed in eleven communities that represented different ethnic and socioeconomic regions of Alaska,
these investigators added nutrient values for 210 foods consumed by Alaska Natives in addition to the
2400 foods present in the Veteran's Administration's nutrient data base. Nobmann et al. (1992) found fish
were an important part of the diet. The mean daily intake of fish and shellfish of Alaska Natives was 109
grams/day. Fish consumption was more frequent in the summer and fall and game meat was eaten more
often in the winter.
Quantitative information on dietary intakes of Native Alaskan populations are few. Estimates can
be derived from harvest survey data, but these have limitations because not all harvested animals are
consumed nor are all edible portions consumed. Other edible portions may be fed to domestic animals
(e.g., sled dogs). Substantial variability in intake of foods including ringed seal, bearded seal, muktuk
(beluga skin with an underlying thin layer of fat) and walrus has been reported (Ayotte et al., 1995).
Dietary analyses on seasonal food intakes of 351 Alaska Native adults from eleven communities
were performed during 1987-1988 (Nobmann et al., 1992). Alaska Natives include Eskimos, Indians and
Aleuts. There is no main agricultural crop in Alaska which when combined with a short growing season,
results in limited availability of edible plants. Alaska Natives have traditionally relied on a diet of fish, sea
mammals, game and a few native plants (seaweed, willow leaves, and sourdock) and berries (such as,
blueberries and salmon berries). Although consumption of significant amounts of commercially produced
foods occurs, use of subsistence foods continues.
The survey sample of 351 adults, aged 21-60 years, was drawn from eleven communities.
Information was obtained using 24-hour dietary recalls during five seasons over an 18-month period. Fish
were consumed much more frequently by Alaska Natives than by the general U.S. population. Fish ranked
as the fourth most frequently consumed food by Alaska Natives compared with the 39th most frequently
consumed food by participants in the nationally representative Second National Health and Nutrition
Assessment Survey (NHANES H). The mean daily intake offish and shellfish for Alaska Natives was 109
4-44
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grams/day contrasted with an intake of 17 grams per day for the general U.S. population described in
NHANES n. Among Alaska Natives fish was consumed more frequently in the summer and fall months.
Several extensive data sets on mercury concentrations in marine mammals consumed by
indigenous populations living in the circumpolar regions have been published (Wagemann et al., 1996;
Caurant et al., 1996; Dietz et al., 1996). Analyses that determined chemically speciated mercury have
shown that mercury present in muscle tissue is largely (>75%) organic mercury (i.e., methylmercury
(Caurant et al., 1996)). By contrast, mercury present in organs such as liver and kidney is predominantly
in an inorganic form (Caurant et al., 1996).
4.1.5.3 Alaskans from Subsistence Economies
Wolfe and Walker (1987) described the productivity and geographic distribution of subsistence
economies in Alaska during the 1980s. Based on a sample of 98 communities, the economic contributions
of harvests of fish, land mammals, marine mammals and other wild resources were analyzed.
Noncommercial fishing and hunting play a major role in the economic and social lives of persons living in
these communities. Harvest sizes in these communities were established by detailed retrospective
interviews with harvesters from a sample of households within each community. Harvests were estimated
for a 12-month period. Data were collected in pounds of dressed weight per capita per year. Although it
varies by community and wildlife species, generally "dressed weight" is approximately 70 to 75% of the
round weight for fish and 20 to 60% of round weight for marine animals. Dressed weight is the portion of
the kill brought into the kitchen for use, including bones for particular species. The category "fish"
contains species including salmon, whitefish, herring, char, halibut, and pike. "Land mammals" included
species such as moose, caribou, deer, black bear, snowshoe and tundra hare, beaver and porcupines.
"Marine mammals" consisted of seal, walrus and whale. "Other" contained birds, marine invertebrates,
and certain plant products such as berries.
Substantial community-to-community variability in the harvesting of fish, land mammals, marine
mammals and other wild resources were noted (Wolfe and Walker, 1985). Units are pounds "dressed
weight" per capita per year. The median harvest was 252 pounds with the highest value approximately
1500 pounds. Wild harvests (quantities offish, land mammals and marine mammals) in 46% of the
sampled Alaskan communities exceeded the western U.S. consumption of meat, fish, and poultry. These
communities have been grouped by general ecological zones which correspond to historic/cultural areas:
Arctic-Subarctic Coast, Aleutian-Pacific Coast, Subarctic Interior, Northwest Coast and contemporary
urban population centers. The Arctic-Subarctic Coast displayed the greatest subsistence harvests of the
five ecological zones (610 pounds per capita), due primarily to the relatively greater harvests of fish and
marine animals. For all regions the fishing output is greater than the hunting; fishing comprises 57 - 68%
of total subsistence output. Above 60° north latitude fishing predominates other wildlife harvests, except
for the extreme Arctic coastal sea mammal-caribou hunting communities. Resource harvests of fish
("dressed weight" on a per capita basis) by ecological zone (and cultural area) were these: Arctic-Subarctic
Coast (Inupiaq-Yup'ik), 363 pounds/year or 452 grams/day; Aleutian-Pacific Coast (Aleut-Sugpiaq), 251
pounds/year or 312 grams/day; Subarctic Interior (Athapaskan), 256 pounds/year or 318 grams/day;
Northwest Coast (Tingit-Haida), 122 pounds/year or 152 grams/day; and Other (Anchorage, Fairbanks,
Juneau, Matanuska-Susitna Borough, and Southern Cook Inlet), 28 pounds/year or 35 grams/day.
Consumption of marine mammals was reported among Yupik Eskimos living in either a coastal or
river village of southwest Alaska (Parkinson et al., 1994). Concentrations of plasma omega-3 fatty acids
were elevated (between 6.8 and 13 times) among the Yupic-speaking Eskimos living in two separate
villages compared with non-Native control subjects (Parkinson et al., 1994). Concentrations of omega-3
fatty acids in plasma phospholipid has been shown to be a valid surrogate of fish consumption (Silverman
4-45
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et al., 1990). Among coastal-village participants the concentrations of eicosapentaonoic and
docosahexaenoic acids reflected higher consumption of marine fish and marine mammals and the use of
seal oil in food preparation. Among river village natives, the increase reflected higher consumption of
salmon.
The Division of Subsistence of the Alaska Department of Fish and Game (Robert J. Wolfe,
personal communications, 1997) has provided estimates of the mean per capita harvests of subsistence fish,
shellfish, and marine mammals in rural Alaska areas (Table 4-36). Combined harvests of
fish/shellfish/marine mammals averaged approximately 350 grams/day for all rural areas combined. The
highest intakes were found in the Western, Interior and Arctic regions with harvests of 693, 577, and 482
grams/day, respectively. Marine mammal consumption was particularly high in the Arctic region with an
average of approximately 270 grams/day consumed. Comparable estimates of marine mammal
consumption were reported by Chan (1997) for an Inuit community based on dietary information gathered
by the Centre for Indigenous Peoples' Nutrition and the Environment (Table 4-37). Using the Centre's
database for contaminants, Chan estimated that mercury intakes were 185 jjg mercury/day with 170 |ug of
mercury coming from marine mammal meat.
Consumption of marine mammals results in very high exposures to methylmercury. Wolfe (1997)
provided data on mean per capita harvest of marine mammals in the Arctic region of rural Alaska of about
290 grams/day. Greater details of types of marine mammals consumed, mercury concentrations found in
these mammals, and estimates of quantities of mammals consumed have been published by Canadian
investigators (Jensen et al. 1997; Chan, 1997) and by the investigators in Greenland and Denmark (Dietz et
al., 1996).
Table 4-36
Mean Per Capita Harvest of Fish and Marine Mammals (g/day)
(Wolfe, personal communication, 1997)
Alaska Rural Area
Southcentral-Prince
William Sound
Kodiak Island
Southeast
Southwest-Aleutian
Interior
Arctic
Western
All Rural Areas
Combined
Fish
114
132
119
299
577
194
605
276
Shellfish
7
17
32
7
0
1
0
11
Marine
Mammals
4
2
7
12
0
267
88
65
Fish/Shellfish
122
149
152
307
577
195
605
267
Fish/Shellfish/
Marine
Mammals
126
152
159
319
577
482
693
352
4-46
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Table 4-37
Estimated Daily Intake of Food and Mercury for Arctic Inuit
(Adapted from Chan, 1997)
Food group
Marine mammal meat
Marine mammal blubber
Terrestrial mammal meat
Terrestial mammal organs
Fish
Birds
Plants
Total
Food (g/day)
199
30
147
1
42
2
2
423
Mercury (ug/day)
170
2.4
4.0
0.9
6.6
0.8
0.0
185
Marine mammals are primarily exposed to methylmercury (Caurant et al., 1996). Mercury present
in flesh of marine mammals is largely methylmercury. For example, Caurant et al. (1996) identified an
average of 78% organic mercury in muscle of pilot whales (Globicepala melas) and 23% organic mercury
in pilot whale liver. Mercury in organs such as liver and kidney appears to be demethylated and stored in a
form combined with selenium, which has been regarded as a detoxification mechanism for the marine
mammals (Caurant et al., 1996). Detailed date on mercury concentration in the northern marine ecosystem
were reported by Dietz et al. (1996) including information on mercury concentration in molluscs,
crustaceans, fish, seabirds, seals, whales, and polar bears.
Among the Inuit in coastal communities of the Canadian Arctic and Greenland, marine mammals
are an important source of food. Food items include the flesh and some organs of ringed seals (Phoca
hispida) and the flesh, but preferentially skin meat and liver of ringed seals and muktuk and blubber of
whales are eaten raw or cooked. Muktuk and the flesh, liver, intestines, and blubber of walrus are also
eaten after fermentation (Wagemann et al., 1996).
Throughout the Arctic, the mean mercury concentration in muscle of beluga whale averaged
between 0.7 and 1.34 ug mercury/gram wet weight of tissue (Wagemann et al., 1996). Muktuk (skin as a
whole) of beluga averaged between approximately 0.6 and 0.8 ug mercury/g wet weight. The skin of
cetaceans (whales, dolphins, porpoises) consists of four layers with the mercury concentration increasing
toward the outermost layers of skin. In this outermost layer of skin, mercury concentration were about 1.5
ug/gram. During molting, about 20% of the total mercury in skin is lost annually. Muscle tissue of
narwhal averaged between 0.8 and 1.0 ug/g, while muktuk averaged around 0.6 ng/g wet weight
(Wagemann et al., 1996). Muscle flesh of ringed seals had average mercury concentrations in the range of
0.4 and 0.7 ug/g with most of the mercury present as methylmercury. Liver mercury concentrations
averaged in the range of 20 to 30 ng/g, but this was primarily present as inorganic mercury. Kidney
contained between 1 and 3 ppm mercury (Wagemann et al., 1996).
Overall, groups consuming muscle and muktuk from marine mammals have much higher
exposures to methylmercury that do groups who consume primarily fish and/or terrestrial mammals. Chan
4-47
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(in press) estimated exposures over 180 (Jg mercury/day for Arctic Inuits. To whatever extent organs
(specifically liver and kidney) are consumed, these typically contain higher concentrations of mercury but
with a lower fraction of methylmercury than found in muscle tissue.
4.1.6 Summary of Canadian Data on Mercury Intake from Fish and Marine Mammals
The Northern Contaminants Program on the Department of Indian Affairs and Northern
Development of the Canadian Government published a compilation of contaminant data including mercury
concentrations in fish and marine mammals (Jensen et al., 1997). Most of the traditionally harvested fish
and land and marine animals consumed are long-lived and are from the higher trophic levels of the food
chain which contain greater concentrations of methylmercury than are found in nonpredatory fish.
Several extensive data sets on mercury concentrations in marine mammals consumed by
indigenous populations living in the circumpolar regions have been published (Wagemann et al., 1996;
Caurant et al., 1996; Dietz et al., 1996). Analyses that determined chemically speciated mercury have
shown that mercury present in muscle tissue is largely (>75%) organic mercury (i.e., methylmercury)
(Caurant et al., 1996). By contrast, mercury present in organs such as liver and kidney is predominantly in
an inorganic form (Caurant et al., 1996).
Wagemann et al. (1997) have provided an overview of mercury concentrations in Arctic whales
and ringed seals. The Inuit in coastal communities of the Canadian Arctic and Greenland hunt and
consume marine mammals for food. The flesh and some organs of ringed seals (Phoca hispida) and flesh
but preferentially skin (muktuk) of belugas (Delphinapterus leucas) and narwal (Monodon monoceros)
contribute significantly to the Inuit diet. Throughout the Arctic, the mean concentrations in Beluga muscle
averaged 0.70 to 1.34 ng mercury/gram wet weight (Wagemann et al., 1996). Mean mercury
concentrations in the muktuk (skin as a whole) of belugas sampled in the western (1993-1994) and the
eastern Arctic (1993-1994) were 0.78 and 0.59 \ig mercury/gram wet weight (Wagemann et al., 1996).
Mean mercury concentrations for narwhal samples collected in the period 1992-1994 were 0.59, 1.03,
10.8, and 1.93 jjg mercury/gram wet weight in muktuk, n uscle, liver, and kidney, respectively (Wagemann
et al., 1996). Muscle tissue of ringed seals contained mercury in concentrations averaging between 0.4 and
approximately 0.7 ng mercury/gram wet weight. Liver tissue averaged between approximately 8 and 30
Hg mercury/gram wet weight. Kidney tissues averaged between 1.5 and 3.2 \ig mercury/gram wet weight.
Extensive data on mercury concentrations in multiple tissues from a wide variety of molluscs,
Crustacea, fish, seabirds, and marine mammals (seals, whales, and porpoises), and polar bears collected in
Greenland were published by Dietz et al. (1996). Chemically speciated mercury concentrations in tissues
of pilot whales have been determined by Caurant et al. (1996). The percent organic mercury (i.e.,
methylmercury) in muscle tissue averaged over 75%. Liver contained a smaller fraction organic mercury,
averaging approximately 23% organic mercury. Marine mammals are principally exposed to
methylmercury, which is the main physico-chemical form of storage in fish (Caurant et al., 1996).
Although demethylation by liver may serve as a means of protecting the marine mammal against adverse
effects of methylmercury, the presence of organic mercury in the marine mammal's muscle means that
consumption of flesh from these mammals will result in exposure to organic mercury.
Jensen et al. (1997) in the Canadian Arctic Contaminants Assessment Report identified wide
variability in the consumption of fish and marine mammals by various aboriginal groups. Chan (1997)
summarized results from an extensive number of dietary surveys of Northern peoples from the Dene
(registered Indian) communities and the Inuit communities (Tables 4-38 and 4-39). The Dene were
estimated to have a mean consumption of 80 grams/day of fish. The Inuit communities were estimated to
have a fish consumption of 42 grams/day, a marine mammal consumption of approximately 230 grams/day
4-48
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Table 4-38
Mercury Concentrations (fig Hg/g wet weight) in Traditional Foods Consumed
by Canadian Aboriginal Peoples
(Modified from Chan, 1997)
Food Group
Marine Mammal Meat
Marine Mammal
Blubber
Terrestrial Mammal
Meat
Terrestrial Mammal
Organs
Fish
Birds
Plants
Number of
Sites
32
6
6
14
799
24
8
Number of
Samples
764
71
19
254
31,441
216
14
Arithmetic
Mean
0.85
0.08
0.03
0.86
0.46
0.38
0.02
Standard
Deviation
1.05
0.05
0.02
0.90
0.52
0.59
0.02
Maximum
33.4
0.13
0.17
3.06
12.3
4.4
0.05
Table 4-39
Estimated Daily Intake of Mercury Using Contaminant Data Base and Dietary Information from
Dene and Inuit Communities in Canada
(Adapted from Chan, 1997)
Food Group
Marine Mammal Meat
Marine Mammal Blubber
Terrestrial Mammal Meat
Terrestrial Mammal Organs
Fish
Birds
Plants
Total
Dene Community
Food
(g/day)
0
0
205
23
80
8
2
318
Mercury
(Hg/day)
0
0
6
20
13
1
0
40
Inuit Community
Food
(g/day)
199
30
147
1
42
2
2
423
Mercury
(ug/day)
170
2
4
1
7
1
0.0
185
(199 grams of meat and 30 grams of blubber). These mean consumptions were associated with a mercury
intake of 39 ug mercury/day for the Dene community and 185 ug mercury/day for an Inuit community.
For the Inuit community, 170 pg mercury/day came from marine mammal meat.
4-49
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4.2 Trends in Fish and Shellfish Consumption in the United States
Description of long-term trends in fish and shellfish consumption are based on data provided by
the National Marine Fisheries Service of the U.S. Department of Commerce. Detailed information on
trends in the 1990s, and forecasts for future production and consumption of fish and shellfish, are based on
projections described in the Annual Report on the United States Seafood Industry published by H.M.
Johnson & Associates (1997).
4.2.1 Fish and Shellfish Consumption: United States. 1975 to 1995
Data for the U.S. consumption and utilization of fish and shellfish have been obtained from the
World Wide Web (http://remora.ssp.mnfs.gov/commercial/landings/index.html). Landings are reported in
pounds of round (i.e., live) weight for all species or groups except univalve and bivalve molluscs, such as
clams, oysters, and scallops. For the univalves and bivalve molluscs, landings are reported as pounds of
meat which excludes shell weight. Landings to not include aquaculture products except for clams and
oysters. Aquaculture products are an increasing source of fish and shellfish for some species of seafood
(Johnson 1997).
U.S. per capita consumption of commercial fish and shellfish has increased from the early part of
this century until present. The major increases occurred post-1970. In 1910, for example, U.S. citizens
consumed an average of 11.0 pounds (edible meats) of commercial fish and shellfish. The consumption in
1970 was 11.8 pounds per capita, but by 1990 had increased to 15.0 pounds per capita.
Two major differences are associated with this trend. First, there was a major increase in
population from 92.2 million persons in 1910, to 201.9 individuals in 1970s, and 247.8 million citizens in
1990. In 1995 (the latest year this source provide statistics), the civilian resident population was estimated
at 261.4 million persons. Combined with increased consumption on a per capita basis, the seafood market
has dramatically increased throughout this century.
The second major change was in availability of transportation and in food processing. Changes
between 1910 and 1995 are shown in Table 4-40. Consumption of cured fish dramatically decreased from
about 36% of per capita intake in 1910, to 2.0% in 1990. Fresh or frozen fish were about 40% of per
capita intake in 1910 and increased to about 67% (two-thirds) offish and shellfish intake by 1990 and
1995. The consumption of canned fish and shellfish changed the least representing about one-fourth of all
fish/shellfish intake in 1910 and about one-third of intake in 1990 and 1995.
Table 4-40
Percent of Fish/Shellfish by Processing Type between 1910 and 1995
(Source: National Marine Fisheries Service, 1997)
Year
1910
1970
1990
1995
Fresh/Frozen
39.1
58.5
64.7
66.7
Canned
24.5
38.1
33.3
31.3
Cured
36.4
4.0
2.0
2.0
4-50
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4.2.1.1 United States: Major Imports and Exports of Fish and Shellfish
During the period 1990 through 1994 the United States was the second largest importer of seven
fishery commodity groups, as well as the second largest exporter of these groups. The largest importer was
Japan and the third largest importer (after the United States) was France followed by Spain, Germany, and
Italy. On a value basis, Canada in the second largest trading partner for the United States after Japan
(Johnson, 1997).
The top five exporters of seafood were Thailand, United States, Norway, Denmark, and China.
Thailand is the leading supplier of seafood to the United States on a value basis, shipping primarily shrimp
(Johnson, 1997). Canada was the leading seafood supplier on a volume basis (Johnson, 1997). The seven
fishery commodity groups are:
1. Fish, fresh, chilled or frozen;
2. Fish, dried, salted, or smoked;
3. Crustaceans and mollusks, fresh, dried, salted, etc.;
4. Fish products and preparations, whether or not in airtight containers;
5. Crustacean and mollusk products and preparations, whether or not in airtight containers;
6. Oils and fats, crude or refined, or aquatic animal origin; and
7. Meals, soluble and similar animal food stuffs of aquatic animal origin.
4.2.1.2 U.S. Supply of Edible Commercial Fishery Products: 1990 and 1995
The supply of the products shown in Table 4-41 is expressed as round or live weight. Any
comparison of these values with food consumption data must consider that the edible portion is smaller
than the live weight. Factors for edible portion compared with live/round weight were published in the
National Research Council's report on Seafood Safety (NRC/NAS, 1990). Total U.S. consumption offish
and shellfish must also include self-caught and recreationally caught fish, as well as other sources that are
not tabulated through commercial channels.
Table 4-41
U.S. Supply of Edible Commercial Fishery Products: 1990 and 1995
(Round or Live Weight in Million Pounds)
Source: National Marine Fisheries Service
Year
1990
1995
Domestic Commercial
Landings
Million
Pounds
7,041
7,783
Percent
55.6
56.8
Imports
Million
Pounds
5,621
5,917
Percent
44.4
43.2
Total
Million
Pounds
12,662
13,700
4-51
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4.2.1.3 U.S. Annual Per Capita Consumption of Canned Fishery Products: 1990 and 1995
Canned tuna is the predominant type of canned fish consumed in the United States averaging
72.4% of all canned fish consumed per capita. Table 4-42 shows U.S. annual per capita consumption of
canned fishery products in 1990 and 1995.
Table 4-42
U.S. Annual Per Capita Consumption of Canned Fishery Products: 1990 and 1995
(Pounds Per Capita)
Year
1990
1995
Salmon
0.4
0.5
Sardines
0.3
0.2
Tuna
3.7
3.4
Shellfish
0.3
0.3
Other
0.4
0.3
Total
5.1
4.7
4.2.1.4 U.S. Annual Per Capita Consumption of Fish Items: 1990 and 1995
In fresh and frozen fish products and shrimp, per capita consumption in these categories is shown
in Table 4-43 based on data from the National Marine Fisheries Service.
Table 4-43
U.S. Annual Per Capita Consumption (in pounds*) of Certain Fishery Items: 1990 and 1995
Year
1990
1995
Fillet and Steaks **
3.1
2.9
Sticks and Portions
1.5
1.2
Shrimp
(All Preparations)
2.2
2.5
* Product weight of fillets and steaks and sticks and portions, edible (meat) weight of shrimp.
** Data include ground fish and other species. Data do not include blocks, but fillets could be made into blocks
from which sticks and portions could be produced.
4.2.1.5 Major Imported Fish and Shellfish Products
The two major fish/shellfish products imported into the United States in 1994 and 1995 (expressed
by weight) were shrimp (621,618,000 pounds in 1994 and 590,634,000 pounds in 1995), and tuna
(including albacore, canned tuna, and other tuna: 707,426,000 pounds in 1994 and 711,241,000 pounds in
1995). Approximately 28% of imported tuna was imported as albacore tuna and about 33% was imported
as canned tuna. Shrimp imports were not differentiated by species of shrimp or country of origin in the
national Marine Fisheries Service statistics.
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4.2.2 Current Market Trends. 1996
The following data on current market trends in the seafood industry are abstracted from the 7997
Annual Report on the United States Seafood Industry describing 1996 data on seafood by H.M. Johnson &
Associates (Johnson, 1997).
The world commercial fish and shellfish supplies increased from 109.6 thousand metric tons in
1994 to 112.0 thousand metric tons in 1995. Aquaculture provided the largest boost to world supply in
1995 increasing 13.6% over the previous year. During this period (1995 to 1996) capture fisheries
declined by 0.1 metric tons. Aquaculture represents 26% of all world food fish (total supply less reduction
fish) products.
The Food and Agriculture Organization examined long-term trends in 77 major fish resources
(representing 77% of the world marine fish landings) are concluded that 35% of the resources were
"overfished," 25% were "fully fished," and 40% had remaining capacity for expansion (FAO, 19%; as
cited by Johnson, 1997).
Aquaculture
World aquaculture continued to increase with 1995 production increased by 14% to 20.9 million
metric tons (Johnson, 1997). Five Asian countries (China, India, Japan, Republic of Korea, and the
Philippines) supplied 80% of aquaculture-raised fish/shellfish. World-wise aquaculture is predicted by the
Food and Agriculture Organization to continued to increase fish and shellfish production beyond the years
2000.
Within the United States, domestic finfish aquaculture increased in 1996. The major increases
were in catfish production. Catfish production very much dominates the U.S. finfish aquaculture
production yielding approximately 475 million pounds round weight/year. Tilapia harvests were higher in
1996, however, trout and salmon production declined. Salmon, trout, and tilapia production are
substantially smaller than catfish production. Yields from U.S. aquaculture for salmon, trout, and tilapia
were under 50 million pounds for each of these species.
4.2.3 Patterns in Fish and Shellfish Consumption: United States. 1996
4.2.3.1 Overall Patterns
Between 1995 and 1996 there was a 0.2 pound decrease in per capita consumption of seafood in
the United States. The principal decline was in canned tuna. The top ten seafoods consumed (expressed
as pounds consumed per capita) were: canned tuna (3.2), shrimp (2.5), Alaska Pollock (1.6); salmon (1.4);
cod (just under 1 pound); catfish (approximately 0.9 pounds); clams (approximately 0.5 pounds), flatfish
(0.4 pounds), crab (approximately 0.3), and scallops (0.3). The source of these data are the National
Marine Fisheries Service and the 1997 Annual Report on the United States Seafood Industry (Johnson,
1997).
4.2.3.2 Fish Intake among Adults
Analysis of the frequency of reporting offish/shellfish and menu items containing fish and
shellfish was carried out using data from CSFJJ 1994 and CSFJJ 1995. Seasons were grouped into six two-
month intervals; i.e., Jan/Feb, Mar/Apr, etc. Data for the 10 most commonly consumed menu items are
shown in Table 4-44. The most frequently reported menu items are "seafood salads and seafood and
4-53
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vegetable dishes." Although other fishery products are possible, this menu category typically describes
dishes made with tuna, surimi (i.e., Alaska pollock), crab, salmon or other canned fish or shellfish.
Overall, these dishes represent about 20% of overall seafood consumption. This major group is followed
by shrimp, canned tuna, the group "Seafood cakes, fritters, and casseroles without vegetables". Identified
finfish commonly consumed include salmon, cod, catfish, flounder, trout, seabass, ocean perch, haddock,
and porgy. Although specific finfish are identified as among the top ten consumed over six seasons, they
follow consumption of processed fishery products; e.g., salads, fritters, "fast food" fillets, and shrimp.
Table 4-44
Ten Most Commonly Reported Fish/Shellfish/Mixed Dishes by Season
CSFII1994 and CSFH 1995 Day 1 Data
Ranking
1st
2nd
3rd
4th
5th
Season
Jan/Feb
Seafood
salads, &
seafood &
vegetable
dishes,
17.6%
Shrimp,
11.2%
Seafood
cakes, fritters
& casseroles
w/o
vegetables,
8.8%
Catfish, 8.3%
Fish
stick/fillet
7.8%
Mar/Apr
Seafood
salads, &
seafood &
vegetable
dishes,
16.9%
Shrimp,
10.5%
Tuna, canned,
10.1%
Seafood
cakes, fritters,
& casseroles
w/o
vegetables,
8.1%
Cod, 5.6%
May/Jun
Seafood
salads, &
seafood &
vegetable
dishes,
24.5%
Shrimp, 9.5%
Tuna, canned,
6.8%
Seafood
cakes, fritters,
& casseroles
w/o
vegetables,
6.4%
Fish
stick.fillet
5.5%
Jul/Aug
Seafood
salads, &
seafood &
vegetable
dishes,
23.2%
Seafood
cakes, fritters,
& casseroles
w/o
vegetables,
7.9%
Tuna, canned
7.5%
Salmon, 6.8%
Shrimp, 6.4%
Sep/Oct
Seafood
salads, &
seafood &
vegetable
dishes,
15.4%
Tuna, canned
12.0%
Shrimp,
11.5%
Seafood
cakes, fritters,
& casseroles
w/o
vegetables,
8.7%
Fish
stick/fillet,
6.7%
Nov/Dec
Seafood
salads, &
seafood &
vegetable
dishes,
20.0%
Shrimp,
11.1%
Seafood
cakes, fritters
& casseroles
w/o
vegetables,
10.0%
Fish
stick/fillet,
9.4%
Fish
stick/fillet,
9.4%
4-54
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Table 4-44 (continued)
Ten Most Commonly Reported Fish/Shellfish/Mixed Dishes by Season
CSFII1994 and CSFII1995 Day 1 Data
Ranking
6th
7th
8th
9th
10th
Season
Jan/Feb
Tuna, canned,
6.3%
Salmon, 3
Trout, 2.4%
Shellfish
dishes in
sauce, 2.4%
Frozen
seafood
dinners, 2.4%
Mar/Apr
Salmon,
5.2%,
Fish,
unspecified,
4.8%
Seafood
sandwiches,
4.0%
Seafood
soups &
casseroles
with
vegetables,
3.6%
Porgy, 3.6%
May/Jun
Salmon, 4.5%
Seafood
sandwiches,
4.1%
Fish,
unspecified
3.6%
Sea bass,
3.2%
Trout,
2.7%
Jul/Aug
Fish
stick/fillet,
5.4%
Catfish,
4.6%
Cod,
4.6%
Ocean perch,
3.2%
Perch,
3.2%
Sep/Oct
Cod,
6.3%
Fish,
unspecified
4.8%
Flounder,
4.3%
Salmon,
3.4%
Catfish, 2.9%
Nov/Dec
Tuna, canned
7.8%
Salmon, 4.4%
Fish
unspecified,
4.4%
Haddock,
3.9%,
Frozen
seafood
dinners, 3.9%
Flounder,
3.3%
Communications with experts in the seafood industry as well as the import/export and productions
statistics published by the National Marine Fisheries Service and the Food and Agriculture Organization)
indicate the predominant species of fish and shellfish are the various species of tuna, shrimp, and the
Alaskan pollock. Superimposed on these broad national trends in fish/shellfish consumption, are regional
trends in fish/shellfish consumption. Table 4-45 describes regional popularity offish species within the
United States.
4-55
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Table 4-45
Regional Popularity of Fish and Shellfish Species
Region
East Coast
South
West Coast
Mid-West
Most Popular Fish Consumed
haddock, cod*, flounder, lobster, blue crab,
shrimp
shrimp, catfish, grouper, red snapper, blue crab
salmon, dungeness crab, shrimp, rockfish
Perch, Walleye, Chubs, Multiple Varities of
Freshwater Fish
*In the late 1990s, cod has been replaced on menus largely by Alaskan pollock.
These impressions are supported by descriptions of the best-selling fish/shellfish species in various
types of restaurants as shown in Table 4-46 (Seafood Business magazine cited by Johnson, 1997, page 71).
Table 4-46
Popularity of Fish/Shellfish Species in Restaurants
Rank
First
Second
Third
By Region:
North East
South
Midwest
West/Pacific
Salmon
Shrimp
Salmon
Salmon
Shrimp
Salmon
Shrimp
Shrimp
Swordfish
Catfish
Cod*
Halibut
By Restaurant Style:
"Fast Food"
"Dinnerhouse"
"White Tablecloth"
Cod*/Shrimp
Shrimp
Salmon
Clams/Scallops
Salmon
Shrimp
Tuna
Lobster
Swordfish
By Overall Sales:
1996
1995
1994
1993
1992
Shrimp
Cod*
Cod*
Cod* (& All Whitefish)
Cod* (& All Whitefish)
Salmon
Shrimp/Salmon
Shrimp/Salmon
Shrimp
Shrimp
Cod*
Swordfish
Swordfish
Hoki
Crab
*In the late 1990s, cod lias been replaced on menus largely by Alaskan pollock.
4-56
-------
Although the species shown in Tables 4-45 and 4-46 are popular regionally, for the United States
as a whole, the national statistics indicate major fish consumed are: tuna, shrimp, and Alaskan pollock.
4.2.3.3 Fish and Shellfish Consumption by Children
The NHANES in data were analyzed to determine the species of fish and shellfish consumed by
children in the age categories l-to-5 years, 6-to-l 1 years, and 12-to-14 years for male and female survey
respondents. Specific choices by age groups are shown in Table 4-47. The top four fish dishes for all age
categories of children were:
fish sticks and patties,
tuna salad and canned tuna,
shrimp, and
catfish.
Table 4-47
Frequencies of Various Fish and Shellfish Food Types
for Children Ages 1 to 5 and 6 to 11 Years by Gender
(Source: NHANES III)
Food Type
Fish Sticks/Patties
Tuna Salad/
Canned Tuna
Shrimp
Catfish
All Other fish and Shellfish
Total
Frequency of Various Food Types
Ages 1-5 Years
Females
23%
33%
8%
5%
31%
100%
Males
21%
27%
6%
5%
41%
100%
Ages 6-11
Females
23%
26%
11%
5%
35%
100%
Males
25%
19%
10%
10%
36%
100%
Ages 12-14
Females
21%
28%
12%
9%
30%
100%
Males
21%
25%
12%
4%
33%
100%
4.2.4 Production Patterns and Mercury Concentrations for Specific Fish and Shellfish Species
Four species of fish are important predictors of methylmercury exposure because of the frequency
with which these are consumed by the overall population.
4.2.4.1
Tuna
Although consumption of canned tuna continues to fall (Johnson, 1997), tuna (canned and fresh or
frozen) continues to be the most commonly consumed fish based on data from contemporary surveys of
food intake by individuals. The mercury concentration of tuna varies with species reflecting variability in
fish size and geographic location.
The mean mercury concentration in tuna is 0.206 ug/gram based on data from NMFS. This
represents an average for the mean concentrations measured in three types of tuna: albacore tuna (0.264
4-57
-------
ug/g), skipjack tuna (0.136 ug/g, and yellowfin tuna (0.218 ug/g). Data cited by U.S. FDA (1978) indicate
the following mean (maximum) values in ug/g for various tuna species: tuna, light skipjack, 0.144 (0.385);
tuna light yellow, 0.271 (0.870); tuna, white 0.350 (0.904). Cramer (1994) observed that recent U.S. FDA
surveys indicated that the mean mercury content of 1973 samples of canned tuna was 0.21 ug/g, whereas a
1990s survey of 245 samples of canned tuna was 0.17 ug/g mercury.
4.2.4.2 Shrimp
Shrimp consumption based on contemporary nationally representative surveys in the United States
continues to be a top-ten seafood choice by both adults and children. World shrimp supplies are in excess
of 3,000,000 metric tons (Johnson, 1997) with approximately one-sixth of the production grown by
aquaculture. This amounts to approximately 500,000 metric tons grown by aquaculture. The United
States is a net importer of shrimp with major suppliers (in order of the quantity imported into the United
States) Thailand, Ecuador, Mexico, and India (Johnson, 1997).
The overall averaged mercury concentration in marine shrimp reported by the NMFS is 0.047
ug/g. This is an average of the mean concentrations measured in seven types of shrimp: royal red shrimp
(0.074 ug/g), white shrimp (0.054 ug/g), brown shrimp; (0.048 ug/g), ocean shrimp (0.053 ug/g), pink
shrimp (0.031 ug/g), pink northern shrimp (0.024 ug/g), and Alaska (sidestripe) shrimp (0.042 ug/g).
Data cited by U.S. FDA (1978) indicate a mean value of 0.040 with a maximum of 0.440 ug/g.
Shrimp consumed in the United States are predominantly imported from Thailand, Ecuador, and
India. The authors of the Report to Congress have not identified data specifically reporting mercury
concentrations in shrimp from the countries which are currently the major suppliers of shrimp to the United
States.
4.2.4.3 Pollock
The Alaskan pollock dominates the U.S. seafood industry. In 1996, pollock landings totaled 2.6
billion pounds (Johnson, 1997). Pollock is the fish species used in preparation offish sticks, fish
sandwiches served by various "fast food" restaurant franchises in the United States, artificial "crab" or
surimi.
The mercury concentration attributed to pollock is 0.15 ug/g based on NMFS data. Data cited by
U.S. FDA indicate a mean mercury concentration for pollock of 0.141 (maximum value, 0.96 ug/g).
4.2.4.4 Salmon
Salmon is a highly important fish species based on frequency of consumption of both the canned
and fresh product. Species include: chinook, coho, chum, sockeye, and pink. Production has declined in
the United States between 1995 and 1996, although the world supply of salmon has continued to grow.
Salmon is one of the major fish species grown by aquaculture with production of approximately 50 million
pounds per year in the United States.
The mercury content used for salmon was the average of the mean concentrations measured in five
types of salmon: pink (0.019 ug/g), chum (0.030 ug/g), coho (0.038 ug/g), sockeye (0.027 ug/g), and
chinook (0.063 ug/g). Salmon that is raised by aquaculture based on consumption of corn and soy
products may have lower mercury concentrations because of the low mercury concentration of the
vegetable products fed to the aquaculture-raised salmon. Data cited by U.S. FDA (1978) indicated a mean
value for salmon of 0.040 (maximum 0.201).
4-58
-------
4.2.4.5 Catfish
Catfish ranks in the top ten fish produced and consumed. Catfish dominates the aquaculture
production in the United States with production of approximately 475 million pounds round (i.e., live)
weight. The mercury concentration of freshwater catfish used in the Mercury Study Report to Congress
was 0.088 u,g/g. Data cited by U.S. FDA (1978) indicate a mean value of 0.146 ng/g (with a maximum
value of 0.38 pg/g). As with salmon, catfish raised by aquaculture on vegetable products (e.g., corn and
soy) are predicted to have lower mercury concentrations than capture catfish.
4.3 Mercury Concentrations In Fish
Mercury concentrations in marine, estuarine, and freshwater fish were obtained from data bases
maintained for marine and estuarine fish and shellfish (National Marine Fisheries Service, 1978) and
freshwater fish (Lowe et al., 1985; and Bahnick et al., 1994). These data combined with estimates of
fish/shellfish consumption from various dietary surveys form the basis for predicted mercury exposures
through fish and shellfish.
4.3.1 National Marine Fisheries Service Data Base
Analyses of total mercury concentrations in marine and estuarine fish and shellfish have been
carried out over the past two to three decades. Data describing methylmercury concentrations in marine
fish were predominantly based on the National Marine Fisheries' Service (NMFS) data base, the largest
publicly available data base on mercury concentrations in marine fish. In the early 1970s, the NMFS
conducted testing for total mercury on over 200 seafood species of commercial and recreational interest
(Hall et al., 1978). The determination of mercury in fish was based on flameless (cold vapor) atomic
absorption spectrophotometry following chemical digestion of the fish sample. These methods were
described in Hall et al. (1978).
Although the NMFS data were initially compiled beginning in the 1970s, comparisons of the
mercury concentration identified in the NMFS's data base with compliance samples obtained by the U.&
FDA indicate that the NMFS data are appropriate to use in estimating intake of mercury from fish at the
national level of data aggregation. Cramer (1994) of the Office of Seafood of the Center for Food Safety
and Applied Nutrition of the U.S. FDA reported on Exposure of U.S. Consumers to Methylmercury from
Fish. He noted that recent information from NMFS indicated that the fish mercury concentrations reported
in the 1978 report do not appear to have changed significantly. The U.S. FDA continues to monitor
methylmercury concentration in seafood. Cramer (1994) observed that results of recent U.S. FDA susveys
indicate results parallel to earlier findings by U.S. FDA and NMFS. To illustrate, Cramer estimated the
mean methylmercury content of the 1973 samples of canned tuna at 0.21 fig/g mercury, whereas a recently
completed survey of 245 samples of canned tuna was 0.17 u,g/g mercury. These data are considered to be
comparable, although the small decrease reported between these two studies may reflect increased useiK
canned tuna of tuna species with slightly lower average methylmercury concentrations. The National
Academy of Sciences' National Research Council's Subcommittee on Seafood Safety (1991) also assessed
the applicability of the NMFS' 1970s data base to current estimates of mercury concentrations in fish. This
subcommittee also concluded that the 1978 data base differed little in mercury concentrations from U.S.
FDA compliance samples estimating mercury concentrations in fish.
Assessment of this data base by persons with expertise in analytical chemistry and patterns of
mercury contamination of the environment have indicated that temporal patterns in mercury concentrations
in fish do not preclude use of this data base in the present risk assessment (US EPA's Science Advisory
Board's ad hoc Mercury Subcommittee; Interagency Peer Review Group, External Peer Review Group)i.
4-59
-------
One issue that did arise, however, concerned how zero and trace values were entered into calculation of
mean mercury concentrations. This has been evaluated statistically through comparison of mean values
when different approaches were taken to mathematically calculated means under different assumptions of
inclusion of zero and trace values.
The NMFS Report provided data on number of samples, number of nondetects, and mean,
standard deviation, minimum and maximum mercury levels (in parts per million wet weight) for 1,333
combinations offish/shellfish species, variety, location caught, and tissue (Hall et al., 1978). This data
base includes 777 fish/shellfish species for which mercury concentration data are provided. This
represents 5,707 analyses of fish and shellfish tissues for total mercury, of which 1,467 or 26%, are
reported as nondetectable levels. Because the mercury concentration data are used in our analyses at the
species level, not at the more detailed species/variety/location/tissue level, the data have been grouped to
reflect 35 different fish/shellfish species.
The frequency of nondetectable or "zero" values differs with the mercury concentration. When
mean mercury levels are relatively "large", there are few, if any, nondetects, so the methodology employed
to handle nondetects is irrelevant. When mean mercury levels are small, there are relatively large numbers
of nondetectable values. Because the method of including/excluding nondetectable values in the
calculation has the greatest impact only when mercury concentrations are very low, the overall impact on
estimated mercury exposure is small.
A statistical assessment of these potential differences was carried out by Westat Corporation
(Memo from Robert Clickner, September 26, 1997). A description of the statistical basis for the
comparison is shown in Appendix C. To determine the detection limit applicable to the data base, the
lowest of all detected analytical values was presumed to be the detection limit. This value is 0.010 |jg/g
wet weight. The major conclusion of this analysis is that different methods of handling nondetects have
negligible impact on the reported mean concentrations. Consequently the mean values as reported by the
NMFS will be used in preparing estimates of mercury intake from marine and estuarine fish and shellfish.
Mercury concentration in various fish species are shown in Table 4-48.
Table 4-48
Summary of Mercury Concentrations in Fish Species
(ug Hg/g fresh weight)
Data Used by USEPA
Mercury Study Report to
Congress*
1997
Fish Species
Abalone
Anchovies
Average
0*8 Hg/g)
0.016
0.047
Data Used by US FDA
Report on the Chance of U.S.
Seafood Consumers Exceeding "The Current
Daily Intake for Mercury and Recommended
Regulatory Controls"
1978
Fish Species
Abalone
Anchovies
Average
(MZ Hg/g)
0.018
0.039
Maximum
Cue Hg/g)
0.120
0.210
Data Used by Stern et al.
1996
Fish
Species
Not
Reported
(MR)
NR
Average
(ME Hg/g)
4-60
-------
Table 4-48 (continued)
Summary of Mercury Concentrations in Fish Species
(fig Hg/g fresh weight)
Data Used by USEPA
Mercury Study Report to
Congress*
1997
Fish Species
Bass,
Freshwater
Bass, Sea
Bluefish
Bluegills
Bonito
Bonito
Butterfish
Carp,
Common
Catfish
(channel.large
mouth, rock,
striped, white)
Catfish
(Marine)
Clams
Cod
Crab, King
Crab
Average
tee Hg/g)
Avgs.= 0.157
(Lowe et al.,
1985) and
0.38 (Bahnick
et al., 1994)
Not Reported
Not Reported
0.033
Not Reported
Not Reported
Not Reported
0.093
0.088
Not Reported
0.023
0.121
0.070;
Calculations
based on 5
species of crab
combined at
0.117
0.117
Data Used by US FDA
Report on the Chance of U.S.
Seafood Consumers Exceeding "The Current
Daily Intake for Mercury and Recommended
Regulatory Controls"
1978
Fish Species
Bass,
Striped
Bass, Sea
Bluefish
Bluegills
Bonito
(below
3197)
Bonito
(above
3197)
Butterfish
Carp
Catfish
(freshwater)
Catfish
(Marine)
Clams
Cod
Crab, King
Crab, other
than King
Average
(MgHg/g)
0.752
0.157
0.370
0.259
0.302
0.382
0.021
0.181
0.146
0.475
0.049
0.125
0.070
0.140
Maximum
(M8 Hg/g)
2.000
0.575
1.255
1.010
0.470
0.740
0.190
0.540
0.380
1.200
0.260
0.590
0.240
0.610
Data Used by Stern eta).
1996
Fish
Species
Bass,
freshwater
Bass, Sea
Bluefish
NR
NR
NR
Butterfish
Catfish,
freshwater
Clams
Cod/Scrod
See crab.
Crab
NR
NR
Average
(MgHpfe)
0.41
0.25
0.35
0.05
0.15
0.05
0.15
0.15
4-61
-------
Table 4-48 (continued)
Summary of Mercury Concentrations in Fish Species
(ug Hg/g fresh weight)
Data Used by USEPA
Mercury Study Report to
Congress*
1997
Fish Species
Crappie
(black, white)
Croaker
Dolphin
Drums,
Freshwater
Flounders
Groupers
Haddock
Hake
Halibut
Halibut
Halibut
Halibut
Herring
Kingfish
Lobster
Lobster
Lobster
Spiny
Mackerel
Average
(MR Hg/g)
0.114
0.125
Not Reported
0.117
0.092
0.089
0.145
0.250
0.250
0.250
0.250
0.013
0.100
0.232
0.232
0.232;
Includes spiny
(Pacific)
lobster=0.210
0.081;
Averaged
Chub = 0.081;
Atlantic=
O.025;
Jack=0.138
Data Used by US FDA
Report on the Chance of U.S.
Seafood Consumers Exceeding "The Current
Daily Intake for Mercury and Recommended
Regulatory Controls"
1978
Fish Species
Crappie
Croaker
Dolphin
Drums
Flounders
Groupers
Haddock
Hake
Halibut 4
Halibut 3
Halibut 2H
Halibut 25
Herring
Kingfish
Lobster,
Northern 1 1
Lobster
Northern 10
Lobster.Spin
y
Mackerel,
Atlantic
Average
(ME Hg/g)
0.262
0.124
0.144
0.150
0.096
0.595
0.109
0.100
0.187
0.284
0.440
0.534
0.023
0.078
0.339
0.509
0.113
0.048
Maximum
G*Hg/g)
1.390
0.810
0.530
0.800
0.880
2.450
0.368
1.100
1.000
1.260
1.460
1.430
0.260
0.330
1.603
2.310
0.370
0.190
Data Used by Stern etal.
1996
Fish
Species
NR
MR
Dolphin
(Mahi-
mahi)
NR
Flounder
NR
Haddock
Hake
Halibut
Halibut
Halibut
Halibut
Herring
Kingfish
Lobster
Lobster
Lobster
Mackerel
Average
(ME Hg/g)
-
0.25
0.10
0.05
0.10
0.25
0.25
0.25
0.25
0.05
0.05
0.25
0.25
0.25
0.28
4-62
-------
Table 4-48 (continued)
Summary of Mercury Concentrations in Fish Species
(ug Hg/g fresh weight)
Data Used by USEPA
Mercury Study Report to
Congress*
1997
Fish Species
Mackerel
Mackerel
Mackerel
Mackerel
Mackerel
Mullet
Oysters
Perch,
White and
Yellow
Perch,
Ocean
Pike,
Northern
Pollock
Pompano
Rockflsh
Sableflsh
Salmon
Scallops
Scup
Sharks
Shrimp
Smelt
Average
teE Hg/g)
0.081
0.081
0.081
0.081
0.081
0.009
0.023
0.110
0.116
0.310
0.127
0.150
0.104
Not Reported
Not Reported
0.035
0.042
Not Reported
1.327
0.047
0.100
Data Used by US FDA
Report on the Chance of U.S.
Seafood Consumers Exceeding "The Current
Daily Intake for Mercury and Recommended
Regulatory Controls"
1978
Fish Species
Mackerel,
Jack
Mackerel,
King (GulO
Mackerel,
King (other)
Mackerel,
Spanish 16
Mackerel,
Spanish 10
Mullet
Ovsters
Perch,
Freshwater
Perch,
Marine
Pike
Pollock
Pompano
Rockfish
Sablefish
Salmon
Scallops
Scup
Sharks
Shrimp
Smelt
Average
(ME Hg/g)
0.267
0.823
1.128
0.542
0.825
0.016
0.027
0.290
0.133
0.810
0.141
0.104
0.340
0.201
0.040
0.058
0.106
1.244
0.040
0.016
Maximum
(MZ Hg/g)
0.510
2.730
2.900
2.470
1.605
0.280
0.460
0.880
0.590
1.710
0.960
8.420
0.930
0.700
0.210
0.220
0.520
4.528
0.440
0.058
Data Used by Stern et al.
1996
Fish
Species
Mackerel
Mackerel
Mackerel
Mackerel
Mackerel
Mullet
NR
Perch
NR
NR
NR
NR
NR
NR
Salmon
NR
NR
Shark
Shrimp
Smelts
Average
teg Hg/g)
0.28
0.28
0.28
0.28
0.28
0.05
0.18
0.05
1.11
0.11
0.05
4-63
-------
Table 4-48 (continued)
Summary of Mercury Concentrations in Fish Species
(ug Hg/g fresh weight)
Data Used by USEPA
Mercury Study Report to
Congress*
1997
Fish Species
Snapper
Snapper
Snook
Spot
Squid
Octopi
Sunfish
Swordfish
Tillefish
Trout,
Trout
Tuna
Tuna
Tuna
Whitefish
Other finfish
Average
(MS Hg/g)
0.25
0.25
Not Reported
Not Reported
0.026
0.029
Not Reported
0.95
Not Reported
0.149
0.149
0.206;
Averaged:
Tuna, light
skipjack=0.13
6Tuna,light
yellow=0.218;
Albacore=0.2
64
0.206
0.206
Not Reported
Data Used by US FDA
Report on the Chance of U.S.
Seafood Consumers Exceeding "The Current
Daily Intake for Mercury and Recommended
Regulatory Controls"
1978
Fish Species
Snapper.Red
Snapper,
Other
Snook
Spot
Squid and
Octopi
Squid and
Octopi
Sunfish
Swordfish
Tillefish
Trout,
Freshwater
Trout,
Marine
Tuna,
Light
Skipjack
Tuna,
Light
Yellow
Tuna, White
Whitefish
Other finfish
Average
(M8 Hg/g)
0.454
0.362
0.701
0.041
0.031
0.031
0312
1.218
1.607
0.417
0.212
0.144
0.271
0.350
0.054
0.287
Maximum
(ME Hg/g)
2.170
1.840
1.640
0.180
0.400
0.400
1.200
2.720
3.730
1.220
1.190
0.385
0.870
0.904
0.230
1.020
Data Used by Stern et al.
1996
Fish
Species
Snapper
Snapper
NR
Spotfish
Squid
NR
NR
Swordfish
NR
Trout
Trout
Tuna,
fresh
Tuna,
fresh
Tuna,
fresh
Whitefish
Finfish,
other
Average
0/gHg/g)
0.31
0:3-1
0.05
0.05
0.93
0.05
0.05
0.17
0.17
0.17
0.04
'0.17
4-64
-------
Table 4-48 (continued)
Summary of Mercury Concentrations in Fish Species
(fig Hg/g fresh weight)
Data Used by USEPA
Mercury Study Report to
Congress*
1997
Fish Species
Other shellfish
Average
(MR Hg/g)
Not
Reported
Data Used by US FDA
Report on the Chance of U.S.
Seafood Consumers Exceeding "The Current
Daily Intake for Mercury and Recommended
Regulatory Controls"
1978
Fish Species
Average
(VR Hg/g)
Maximum
(ME Hg/g)
Data Used by Stern etal.
1996
Fish
Species
Shellfish,
other
Average
(Mg Hg/R)
0.12
Fish Species (Freshwater) Not Reported by FDA, 1978
Bloater
Smallmouth
Buffalo
Northern
Squawfish
Sauger
Sucker
Walleye
Trout (brown,
lake, rainbow)
0.0.93
0.096
0.33
0.23
0.1 14 (Lowe
et al., 1985;
0.167
(Bahnick et
al., 1994).
0.1 00 (Lowe
et al., 1985)
and 0.52
(Bahnick et
al., 1994).
0.1 49 (Lowe
etal., 1985)
and 0.14
(Bahnick et
al., 1994 for
brown trout).
Fish Species Reported by the State of New Jersey
and Not Reported by EPA or FDA
Blowfish
Orange roughy
Sole
Weakfish
Porgy
Blackfish
0.05
0.5
0.12
0.15
0.55
0.25
4-65
-------
Table 4-48 (continued)
Summary of Mercury Concentrations in Fish Species
(ug Hg/g fresh weight)
Data Used by USEPA
Mercury Study Report to
Congress*
1997
Fish Species
Whiting
Turbot
Sardines
Tilapia
Average
(MR Hg/g)
Data Used by US FDA
Report on the Chance of U.S.
Seafood Consumers Exceeding "The Current
Daily Intake for Mercury and Recommended
Regulatory Controls"
1978
Fish Species
Average
(MK Hg/g)
Maximum
G« Hg/g)
Data Used by Stern etal.
1996
Fish
Species
Average
(MR Hg/g)
0.05
0.10
0.05
0.05
* See Sections 4.3.1 and 4.3.2 for data on marine species, and Section 4.3.3 for data on freshwater fish.
4.3.2 Mercury Concentrations in Marine Fish
Data supplied by NMFS give the mercury concentrations in fresh weight of fish muscle of
numerous marine fish, shellfish, and other molluscan/crustacean species shown in Table 4-49, 4-50 and
4-51.
Table 4-49
Mercury Concentrations in Marine Finfish
Fish
Anchovy1
Barracuda, Pacific2
Cod3
Croaker, Atlantic
Eel, American
Flounder4
Haddock
Hake5
Halibut6
Herring7
Kingfish*
Mercury Concentration
C-ig/g, wet weight)
0.047
0.177
0.121
0.125
0.213
0.092
0.089
0.145
0.25
0.013
0.10
Source of Data
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
4-66
-------
Table 4-49 (continued)
Mercury Concentrations in Marine Finfish
Fish
Mackerel9
Mullet10
Ocean Perch11
Pollack
Pompano
Porgy
Ray
Salmon12
Sardines13
Sea Bass
Shark14
Skate15
Smelt, Rainbow
Snapper16
Sturgeon17
Swordfish
Tuna18
Whiting (silver hake)
Mercury Concentration
(/xg/g, wet weight)
0.081
0.009
0.116
0.15
0.104
0.522
0.176
0.035
0.1
0.135
1.327
0.176
0.1
0.25
0.235
0.95
0.206
0.041
Source of Data
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
FDA Compliance Testing
NMFS
NMFS
' This is the average of NMFS mean mercury concentrations for both striped anchovy (0.082 wg/g) and northern anchovy (0.010
2 USDA data base specified the consumption of the Pacific barracuda and not the Atlantic barracuda.
3 The mercury content for cod is the average of the mean concentrations in Atlantic cod (0.1 14 /^g/g and the Pacific cod (0.127
4 The mercury content for flounder is the average of the mean concentrations measured in 9 types of flounder: Gulf (0.147 ^g/g),
summer (0.127 ^g/g), southern (0.078 ^g/g), four-spot (0.090 ^g/g), windowpane (0.151 /jg/g), arrowtooth (0.020 Mg/g), witch
(0.083 /jg/g), yellowtail (0.067 Mg/g), and winter (0.066 jig/g).
5 The mercury content for hake is the average of the mean concentrations measured in 6 types of hake: silver (0.041 //g/g),
Pacific (0.091 ^g/g), spotted (0.042 //g/g), red (0.076 ^g/g), white (0.1 12 ^g/g), and blue (0.405 Mg/g)-
' The mercury content for halibut is the average of the mean concentrations measured in 3 types of halibut: Greenland, Atlantic,
and Pacific.
1 The mercury content for herring is the average of the mean concentrations measured in 4 types of herring: blueback (0.0 ^g/g),
Atlantic (0.012 A
-------
IJ The mercury content for salmon is the average of the mean concentrations measured in 5 types of salmon: pink (0.019 /ug/g).
chum (0.030 ng/g), coho (0.038 ng/g), sockeye (0.027 Mg/g), and chinook (0.063 Mg/g).
13 Sardines were estimated from mercury concentrations in small Atlantic herring.
14 The mercury content for shark is the average of the mean concentrations measured in 9 types of shark: spiny dogfish (0.607
Aig/g), (unclassified) dogfish (0.477 f*g/g), smooth dogfish (0.991 ^g/g), scalloped hammerhead (2.088 /vg/g), smooth
hammerhead (2.663 ng/g), shortfin mako (2.539 Mg/g), blacktip shark (0.703 ^g/g), sandbar shark (1.397 Mg/g), and thresher
shark (0.481 ng/g).
15 The mercury content for skate is the average of the mean concentrations measured in 3 types of skate: thorny skate (0.200
Uglg), little skate 0.135 uglg) and the winter skate (0.193 ng/g).
14 The mercury content for snapper is the average of the mean concentrations measured in types of snapper:
17 The mercury content for sturgeon is the average of the mean concentrations measured in 2 types of sturgeon:green sturgeon
(0.218 A/g/g) and white sturgeon (0.251 Mg/g).
18 The mercury content for tuna is the average of the mean concentrations measured in 3 types of tuna: albacore tuna (0.264
Vg/g), skipjack tuna (0.136 uglg) and yellowfm tuna (0.218 ng/g).
Table 4-50
Mercury Concentrations in Marine Shellfish
Shellfish
Abalone1
Clam2
Crab3
Lobster4
Oysters5
Scallop6
Shrimp7
Mercury Concentration
(//g/g, wet weight)
0.016
0.023
0.117
0.232
0.023
0.042
0.047
Source of Data
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
' The mercury content for abalone is the average of the mean concentrations measured in 2 types of abalone: green abalone
(0.011 Mg/g) and red abalone (0.021 ng/g).
2 The mercury content for clam is the average of the mean concentrations measured in 4 types of clam: hard (or quahog) clam
(0.034 Mg/g), Pacific littleneck clam (0 vgfg), soft clam (0.027 /ug/g), and geoduck clam (0.032 f^g/g).
3 The mercury content for crab is the average of the mean concentrations measured in 5 types of crab: blue crab (0.140 ng/g),
dungeness crab (0.183 vg/g), king crab (0.070 ng/g), tanner crab (C.opilio) (0.088 ug/g), and tanner crab (C.bairdi) (0.1
' The mercury content for lobster is the average of the mean concentrations measured in 3 types of lobster: spiny (Atlantic)
lobster (0.108 vglg), spiny (Pacific) lobster (0.210 Mg/g) and northern (American) lobster (0.378 f^g/g).
5 The mercury content for oyster is the average of the mean concentrations measured in 2 types of oyster: eastern oyster (0.022
Hg/g) and Pacific (giant) oyster (0.023 /^g/g).
6 The mercury content for scallop is the average of the mean concentrations measured in 4 types of scallop: sea (smooth) scallop
(0.101 //g/g), Atlantic Bay scallop (0.038 /ug/g), calico scallop (0.026 ng/g), and pink scallop (0.004 i/g/g).
7 The mercury content for shrimp is the average of the mean concentrations measured in 7 types of shrimp: royal red shrimp
(0.074 /ug/g), white shrimp (0.054 ^g/g), brown shrimp (0.048 ng/g), ocean shrimp (0.053 f^g/g), pink shrimp (0.031 ^g/g), pink
northern shrimp (0.024 Mg/g) and Alaska (sidestripe) shrimp (0.042 ug/g).
4-68
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Table 4-51
Mercury Concentrations in Marine Moliuscan Cephalopods
Cephalopod
Octopus
Squid1
Mercury Concentration
(//g/g wet wt.)
0.029
0.026
Source of Data
NMFS
NMFS
1 The mercury content for squid is the average of the mean concentrations measured in 3 types of squid: Atlantic
longfinned squid (0.025 A'g/g), short-finned squid (0.034 //g/g), and Pacific squid (0.018 A
-------
a detection limit of 0.05 ug/g. Modification of the method for the final 195 samples produced a detection
limit of 0.0013 ug/g. The estimated standard deviation for replicate samples was 0.047 ug/g in the
concentration range of 0.08 to 1.79 ug/g. Analysis of EPA reference fish having a reported experimental
mean value of 2.52 ug/g (s=0.64) produced a mean value for mercury of 2.87 (s=0.08) in this study. The
mean value for the overall data set for 669 samples was 0.26 ug/g. Mercury was detected in fish collected
from the 374 sites.
Because mercury emissions from the ambient sources considered in the current Report to Congress
have different impacts on global and local deposition, it was considered important to separate fish species
by habitat. Specifically, global mercury cycling was judged to have its greatest impact on marine species,
whereas local deposition was considered more likely to affect estuarine and freshwater fish and shellfish
species. The species were classified as shown in Table 4-14 on a classification system described by Jacobs
et al. (in press).
Central tendency estimates of seafood mercury concentrations were utilized in the report. This
seems appropriate since commercial seafood is widely distributed across the United States (Seafood Safety,
1991). The source of a particular fish purchase is generally not noted by the consumer (e.g., canned tuna).
As a result, a randomness and averaging may be achieved. Additionally, only common names of
commercial seafood were utilized; specific species which could be considered to be that type of fish were
included in the central tendency estimate. Again, typical consumers were assumed to generally not be
aware of the species offish they were consuming, rather just the type.
As noted above, there are other estimates of mercury concentrations in seafood. After the analysis
of mercury exposure from seafood was completed for this Report, two other databases were obtained: U.S.
FDA and Stern et al. (1996). These data are presented in Table 4-51 for comparison with those data used
for this analysis.
4.3.4 Mercury Concentrations In Freshwater Fish
Estimation of average mercury concentrations in freshwater finfish from across the United States
required a compilation of measurements of fish mercury concentrations from randomly selected U.S. water
bodies. A large number of sources of mercury concentrations in fish were not used in this part of the
assessment. Mercury concentrations in fish have been analyzed for a number of years in many local or
regional water bodies in the United States; several of these studies are detailed in this Report. Data
described in this body of literature are a collection of individual studies which characterize mercury
concentrations in fish from specific geographic regions such as individual water bodies or in individual
states. Many of the studies were initiated because of a problem, perceived or otherwise, with mercury
concentrations in the fish or the water body. Thus, the sample presented by a compilation of these data
may be biased toward the high-end of the distribution of mercury concentrations in freshwater fish.
Additionally, the methods varied from study to study, and there is no way of determining the consistency
of the reported data from study to study.
Two studies, more national in scope, are thought to provide a more complete picture of mercury
concentrations in U.S. freshwater finfish populations: "National Contaminant Biomonitoring Program:
Concentrations of Seven Elements in Freshwater Fish, 1978-1981" by Lowe et al. (1985) and "A National
Study of Chemical Residues in Fish" conducted by U.S. EPA (1992) and also reported in Bahnick et al.
(1994).
Lowe et al. (1985) reported mercury concentrations in fish from the National Contaminant
Biomonitoring Program. The freshwater fish data were collected between 1978-1981 at 112 stations
4-70
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located across the United States. Mercury was measured by a flameless cold vapor technique, and the
detection limit was 0.01 |jg/g wet weight. Most of the sampled fish were taken from rivers (93 of the 112
sample sites were rivers); the other 19 sites included larger lakes, canals, and streams. Fish weights and
lengths were consistently recorded. A wide variety of types of fishes were sampled: most commonly carp,
large mouth bass and white sucker. The geometric mean mercury concentration of all sampled fish was
0.11 fjg/g wet weight; the minimum and maximum concentrations reported were 0.01 and 0.77 jjg/g wet
'weight, respectively. The highest reported mercury concentrations (0.77 ng/g wet weight) occurred in the
northern squawfish of the Columbia River. See Table 4-53 for mean mercury concentrations by fish
species.
Table 4-53
Freshwater Fish Mercury Concentrations from Lowe et al., (1985)
Species
Bass
Bloater
Bluegill
Smallmouth Buffalo
Carp, Common
Catfish (channel, largemouth, rock, striped, white)
Crappie (black, white)
Fresh-water Drum
Northern Squawfish
Northern Pike
Perch (white and yellow)
Sauger
Sucker (bridgelip, carpsucker, klamath, largescale, longnose,
rivercarpsucker, tahoe)
Trout (brown, lake, rainbow)
Walleye
Mean of all measured fish
Mean Mercury Concentration fig/g
(fresh weight)
0.157
0.093
0.033
0.096
0.093
0.088
0.114
0.117
0.33
0.127
0.11
0.23
0.114
0.149
0.100
0.11
"A National Study of Chemical Residues in Fish" was conducted by U.S. EPA (1992) and also
reported by Bahnick et al. (1994). In this study mercury concentrations in fish tissue were analyzed. Five
bottom feeders (e.g., carp) and five game fish (e.g., bass) were sampled at each of the 314 sampling sites in
the United States. The sites were selected based on proximity to either point or non-point pollution
sources. Thirty-five "remote" sites among the 314 were included to provide background pollutant
concentrations. The study primarily targeted sites that were expected to be impacted by increased dioxin
levels. The point sources proximate to sites of fish collection included the following: pulp and paper
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mills, Superfund sites, publicly owned treatment works and other industrial sites. Data describing fish age,
weight, and sex were not consistently collected. Whole body mercury concentrations were determined for
bottom feeders and mercury concentrations in fillets were analyzed for the game fish. Total mercury levels
were analyzed using flameless atomic absorption; the reported detection limits were 0.05 ug/g early in the
study and 0.0013 ug/g as analytical technique improved later in the analysis. Mercury was detected in fish
at 92% of the sample sites. The maximum mercury level detected was 1.8 ug/g, and the mean across all
fish and all sites was 0.26 ug/g. The highest measurements occurred in walleye, large mouth bass and
carp. The mercury concentrations in fish around publicly owned treatment works were highest of all point
source data; the median value measured were 0.61 ug/g. Paper mills were located near many of the sites
where mercury-laden fish was detected. Table 4-54 contains the mean mercury concentrations of the
species collected by Bahnick et al. (1994).
Both the studies reported by Lowe et al. (1985) and by Bahnick et al. (1994) appear to be
systematic, national collections of fish pollutant concentration data. Clearly, higher mercury
concentrations in fish have been detected in other analyses, and the values obtained in these studies should
be interpreted as a rough approximation of the mean concentrations in freshwater finfishes. As indicated
in the range of data presented in Tables 4-53 and 4-54, as well as the aforementioned Tables in Chapter 2,
wide variations are expected in data on mercury concentrations in freshwater fish.
The mean mercury concentrations in all fish sampled vary by a factor of two between the studies.
The mean mercury concentration reported by Lowe et al.(1985) was 0.11 ug/g, whereas the mean mercury
concentration reported by Bahnick et al. (1994) was 0.26 ug/g. This difference can be extended to the
highest reported mean concentrations in fish species. Note that the average mercury concentrations in bass
and walleye reported by Bahnick's data are higher than the northern squawfish, which is the species with
the highest mean concentration of mercury identified by Lowe et al. (1985).
The bases for these differences in methylmercury concentrations are not immediately obvious.
The trophic positions of the species sampled, the sizes of the fish, or ages of fish sampled could
significantly increase or decrease the reported mean mercury concentration. Older and larger fish, which
occupy higher trophic positions in the aquatic food chain, would, all other factors being equal, be expected
to have higher mercury concentrations. The sources of the fish also influence fish mercury concentrations.
Most of the fish obtained by Lowe et al. (1985) were from rivers. The fate and transport of mercury in
river systems is less well characterized than in small lakes. Most of the data collected by Bahnick et al.
(1994) were collected with a bias toward more contaminated/industrialized sites, although not sites
specifically contaminated with mercury. It could be that there is more mercury available to the aquatic
food chains at the sites reported by Bahnick et al. (1994). Finally, the increase in the more recent data as
reported in Bahnick et al. (1994) could be the result of temporal increases in mercury concentrations.
There is a degree of uncertainty in the mercury concentrations selected for this assessment. This
uncertainty reflects both the adequacy of the sampling protocol for this application and the known
variability in fish body burden. The variability in these data is as broad as the range of reported
concentrations, which extends from non-detect (below 0.01 ug/g wet weight) up to 9 ug/g wet weight.
Where possible, when specific freshwater fish species are described in the USDA 3-day consumption
studies, the mean methylmercury concentration for that particular species was derived in two separate
calculations based on the data on methylmercury concentration in the fish reported by Lowe et al. (1985)
and by Bahnick et al. (1994).
Data for mean mercury concentration in freshwater fish from Bahnick et al. (1994) were combined
with the U.S. consumption rates for freshwater fish from the CSFH 89-91, CSFH 1994, CSFH 1995, and
NHANES in to estimate methylmercury intakes for the population. The concentrations in the fish utilized
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are shown in Table 4-54. The exposure estimates for freshwater fin fish consumption are found in Table
4-55. Bahnick et al. (1994) freshwater fish concentration data were utilized, along with data on mercury
concentrations in marine fish and shellfish (Tables 4-48,4-49,4-50) to calculate total exposure, for general
U.S. population, to mercury through consumption of fish and shellfish (shown in Table 4-55).
Some species of freshwater fishes were not sampled by Bahnick et al. (1994), and some
respondents in the USDA CSFII 89-91 survey did not identify the type of freshwater fish consumed. In
these situations, it was assumed that the fish consumed contained 0.26 ug methylmercury/g, which
is the average of all sampled fish Bahnick et al. (1994). It is important to note that the freshwater fish data
are for wild populations not farm-raised fish.
Table 4-54
Mercury Concentrations in Freshwater Fish
U.S. EPA (1992) and Bahnick et al. (1994)
Freshwater Fish
Carp
Sucker1
Catfish, Channel and Flathead
Bass2
Walleye
Northern Pike
Crappie
Brown Trout
Mean All Fish Sampled
Average Mercury Concentration (yug/g, wet weight)
0.11
0.167
0.16
0.38
0.52
0.31
0.22
0.14
0.26
1 The value presented is the mean of the average concentrations found in three types of sucker fish (white, redhorse and spotter).
- The value presented is the mean of the average concentrations found in three types of bass (white, largemouth and smallmouth).
4.3.5 Calculation of Mercury Concentrations in Fish Dishes
To estimate the mercury intake from fish and fish dishes reported as consumed by respondents in
the CSFII surveys and NHANES HI survey, several steps were taken. Using the Recipe File available
from USDA, the fish species for a particular reported food was identified. The average mercury
concentration in fish tissue on a fresh (or wet) weight basis was identified using the NMFS data or the data
reported by Bahnick et al. (1994). The food intake of the U.S. population includes a large number of
components of aquatic origin. A few of these appear not to have been analyzed for mercury
concentrations. Methylmercury concentration data were not available for some infrequently consumed
food items; e.g., turtle, roe or jelly fish. Data on the quantity of fish present in commercially prepared
soups were also not available and were excluded from the analysis.
Physical changes occur to a food when it is processed and/or cooked. The NMFS and Bahnick et
al. (1994) data bases were used to estimate mercury intake report mercury concentrations on a ug mercury
4-73
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per gram of fresh tissue basis. Earlier research (Bloom, 1992) indicated that over 90% of mercury present
in fish and shellfish is chemically speciated as methylmercury which is bound to protein in fish tissue.
Morgan et al. (1994) indicated that over 90% of mercury present in fish and shellfish is chemically
speciated as methylmercury. Consequently the quantity of methylmercury present in the fish tissue in the
raw state will remain in the cooked or processed fish. In cooking or processing raw fish, there is typically a
reduction in the percent moisture in the food. Thus, mercury concentration data were recalculated to
reflect the loss of moisture during food processing, as well as retention of methylmercury in the remaining
lowered-moisture content fish tissues. Standard estimates of cooking/processing-related weight reductions
were provided by Dr. Betty Perloff and Dr. Jacob Exler, experts in the USDA recipe file and in USDA's
food composition. Percent moisture lost for baked or broiled fish was 25%. Fried fish products lose
weight through loss of moisture but add weight from fat added during frying for a total weight loss of
minus 12%. The percent moisture in fish that were dried, pickled or smoked was identified for individual
fish species (e.g., herring, cod, trout, etc.) from USDA handbooks of food composition. Information on
the percent moisture in the raw, and in the dried, smoked or pickled fish was obtained. The methylmercury
concentration in the fish was recalculated to reflect the increased methylmercury concentration of the fish
as the percent moisture decreased in the drying, pickling or smoking process.
The mean mercury concentrations for all fish from Lowe et al. (1985) and Bahnick et al. (1994)
were combined with the freshwater fish consumption data to estimate a range of exposure from total fish
consumption. Given the human fish consumption rates and the differences between the mercury
concentrations in the two data sets, it is important to use data from both studies of mercury exposures to
assess mean concentrations in fish. For purposes of comparison both sets of data were utilized to illustrate
the predicted methylmercury exposure. For this comparison, the average mercury concentrations for fish
in the Lowe and the Bahnick data were analyzed separately by combining the freshwater fish data with the
data in Tables 4-48 through 4-50. The bodyweight data and the freshwater fish consumption rates were
obtained from Table 4-12. Exposure to methylmercury based on an assumption of 0.11 ug
methylmercury/g fish tissue (wet weight) (Lowe et al., 1985). These values are estimated on a body weight
basis. Tables 4-53 and 4-54 were developed using the mean data on mercury concentrations for all fishes
sampled for these two studies.
Human mercury intake from fish was estimated by combining data on mercury concentration in
fish species with the reported quantities and types of fish species reported as consumed by "users" in the
national food consumption surveys. The mercury concentrations in the consumed fish reported by the
national surveys were estimated using data on mercury concentration in fish expressed as micrograms of
mercury per gram fresh-weight offish tissue.
The CSFH 89-91, CSFII 1994, and CSFH 1995 are three of the USDA's food consumption
surveys. An additional nationally-based food consumption survey is the third National Health and
Nutrition Examination Survey. The food items reported by individuals interviewed in these surveys are
identified by 7-digit food codes. The USDA has developed a recipe file identifying the primary
components that make up the food or dish reported "as Eaten" by a survey respondent. The total weight of
a fish-containing food is typically not 100% fish. The food code specifies a preparation method and gives
additional ingredients used in preparation of the dish. For example, in the Recipe File "Fish, floured or
breaded, fried" contains 84% fish, by weight. Fish dishes contained a wide range offish; from
approximately 5% for a frozen "shrimp chow mein dinner with egg roll and peppers" to 100% for fish
consumed raw, such as raw shark.
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4.4 Intake of Methylmercury from Fish/fish Dishes
Estimates of methylmercury intake from fish and shellfish have been made based on dietary survey
data from the nationally representative surveys (CSFn 89-91, CSFH 94, CSFH 95, and NHANES HI).
Projected month-long estimates of fish/shellfish intake and mercury exposure have been developed from
the NHANES IH frequency of fish consumption data using data from the adult participants in NHANES in
and the 24-hour recall data from children and adults in NHANES DDL These month-long projections are
considered to be the descriptions of mercury exposure from fish and shellfish that are most relevant to the
health endpoint used as the basis for the RfD; i.e. developmental deficits in children following maternal
exposure to methylmercury. Based on input from the interagency review a determination has been made
that comparison of 24-hour "per user" data is generally inappropriate and will not be done except when
describing subpopulations who eat fish/shellfish almost every day.
4.4.1 Intakes "per User" and "per Capita"
The data from major nationally based surveys of the general population are from CSFII 89-91,
CSFH 1994, CSFH 1995, and NHANES m conducted between 1988 and 1994. CSFn 89-91 obtained 3-
days of dietary history based on 24-hour recall interviews. CSFH 1994 and CSFH 1995 obtained two days
of dietary history also obtained by 24-hour recall interview techniques. These two days of dietary recalls
were not necessarily sequential days. Interviewers in NHANES ffl obtained the respondents' estimate of
the number of times per day, per week, and per months the respondent consumed fish/shellfish over the
past 12-month period. These data were obtained only for persons 12 years of age and older. In addition,
recall data on fish/shellfish consumption were obtained on the same respondents as were questionnaire
responses of the frequency of food consumption. These recall data cover the 24-hour period prior to the
interview.
The number and percent of respondents reporting consumption of fish and/or shellfish in these
surveys in shown in Tables 4-55 to 4-57. Intake data can be expressed on a "per capita" basis which
reports the statistics calculated for all survey participants whether or not they reported consuming fish
and/or shellfish during the recall period. By contrast, "per user" statistics are calculated for only those
individuals who reported consuming fish and/or shellfish during the recall periods. The percent of survey
respondents who reported consuming fish and/or shellfish on one 24-hour recall ranged from 11.3 to
12.9% in the nationally-based contemporary food consumption surveys (Table 4-54).
Table 4-55
CSFII 89-91 Number of Respondents - All Age Groups
Total
Fish Consumers
Ages 14 and
Younger
2893
720
Ages 15 through
45
4968
1510
Ages 46 and
Older
3545
1384
Total
11,706
3614
4-75
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Table 4-56
CSFII 89-91 Adult Respondents
Gender
Males
Females
Ages 15 to 45 Years
2131
2837
Ages 46 Years and Older
1537
2308
Total for All Age
Groups
3668
5145
Respondents Reporting Fish Consumption
Gender
Males
Females
Total
Ages 15 to 45 Years
646
864
1510
Ages 46 Years and Older
556
828
1384
Total for All Age
Groups
1202
1692
2894
Table 4-57
Contemporary Dietary Surveys 1990s
General U.S. Population
Survey
NHANES ffl
CSFII 94 - Day 1
CSFII 94 - Day 2
CSFII 95 - Day 1
CSFII 95 - Day 2
Total Number of
Subjects
29,989
5,296
5,293
5063
5062
Number Reporting
Fish/shellfish
Consumption
3864
598
596
601
620
Percent Consuming
Fish/shellfish
12.9
11.3
11.3
11.9
12.2
4.4.1.1
"Per Capita" Consumption
"Per capita" data for CSFH 89-91 are shown in Table 4-58. Data in CSFH 89-91 reflect averages
calculated from three days of 24-hour recall data. Data for the more-recently conducted national surveys
are shown in Table 4-59. These data were obtained by interview and describe fish/shellfish consumption
in the previous 24-hour period. Interviewers describe two 24-hour recalls per respondent.
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Table 4-58
Per Capita Fish/Shellfish Consumption (gins/day) and
Mercury Exposure (ug/kg body weight/day) From CSFII 89-91
Based on Average of Three 24-Hour Recalls
Fish/shellfish
Consumption
Mercury
Exposure
25th
Zero
Zero
50th
Zero
Zero
75th
16
0.04
95th
73
0.24
Maximum
461
2.76
Table 4-59
Per Capita Fish/Shellfish Consumption
Based on Individual Days of 24-Hour Recall Data
General U.S. Population Surveys 1990s
Survey
CSFH 94 - Day 1
CSFII 94 - Day 2
CSFII 95 - Day 1
CSFII 95 - Day 2
NHANES III
10th
Zero
Zero
Zero
Zero
Zero
50th
Zero
Zero
Zero
Zero
Zero
90th
32
0.03
37
0.03
43
0.04
43
0.05
56
0.08
95th
85
0.13
85
0.14
105
0.13
98
0.17
114
0.19
Maximum
457
3.76
606
4.03
960
5.93
1084
2.63
1260
6.96
4.4.1.2
"Per User" Consumption
If statistics are calculated only on those individuals who reported consuming fish and/or shellfish
during the recall period "per user" values are calculated. Data from the average (i.e., mean) of three days
of 24-hour recalls reported in the CSFII 1989-1991 survey are shown in Table 4-60. Data for the
individual two days recorded in CSFII 1994 and in CSFII 1995, and for the single day's 24-hour recall in
NHANES ffl are shown in Table 4-61.
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Table 4-60
Per User Fish/Shellfish Consumption (grams per day) and
Mercury Exposure (ng/kg bw/day) Based
on Average of Three 24-Hour Recalls CSFn 89-91
Fish/shellfish
Consumption
Mercury
Exposure
25th
19
0.04
50th
32
0.09
75th
57
0.18
95th
117
0.45
Maximum
461
2.76
Table 4-61
"Per User" Intake of Fish and Shellfish (gms/day) and Exposure to Mercury (ng Hg/kg bw/day)
Among Individuals Reporting Consumption, Based on Individual Day Recall Data
Study
CSFH 94 - Day 1
n=598
CSFII 94 - Day 2
n=596
CSFH 95 - Day 1
n=601
CSFII 95 - Day 2
n = 620
NHANES III
n=3,864
10th
28
0.02
26
0.03
28
0.03
24
0.03
22
0.01
50th
76
0.11
74
0.11
84
0.10
79
0.12
73
0.11
90th
186
0.43
200
0.40
197
0.42
216
0.47
242
0.44
95th
252
0.65
282
0.65
261
0.61
285
0.64
336
0.63
Maximum
458
3.76
606
1.03
960
5.93
1084
2.63
1260
6.95
4.4.2 Methvlmercury Intake from Fish and Shellfish among Women of Child-bearing Age and Children
Subgroups at increased risk of exposure and/or toxic effects of mercury among the general
population include women of childbearing age and children. Exposures to women of childbearing age are
of particular interest because methylmercury is a developmental toxin (Tables 4-62 and 4-63).
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Table 4-62
"Per Capita" Fish/Shellfish Consumption (grams/day) and
Mercury Exposure (ug/kg bw/day) Based
on Average of Three 24-Hour Dietary Recalls CSFH 89-91
Females Aged 15-45
Fish/shellfish Consumption
Mercury Exposure
25th
Zero
Zero
50th
Zero
Zero
75th
15
0.03
95th
72
0.20
Maximum
Value
461
2.76
Table 4-63
"Per User" Fish/Shellfish Consumption (grams/day) and
Mercury Exposure (fig/kg bw/day) Based
on Average of Three 24-Hour Dietary Recalls CSFH 89-91
Females Aged 15-45
Fish/shellfish Consumption
Mercury Exposure
25th
19
0.04
50th
31
0.08
75th
56
0.16
95th
113
0.33
Maximum
Value
461
2.76
Children consume more food on a body weight basis than do adults. Consequently children have
higher exposures to a variety of food contaminants (National Academy of Sciences, 1993 ) including
mercury. Overall, approximately 11 to 13 % of adults report fish/shellfish consumption in short-term
consumption estimates based on single 24-hour recall data. For children, the percent who report fish
consumption in similar surveys is about 8 to 9%.
Looking at the quantity of fish consumed and the intake of mercury on a body weight basis (i.e.,
ug Hg/kg body weight/day), the highest environmental dose of mercury from consumption of fish and
shellfish is found among children (Tables 4-64 and 4-65) based on fish intake and mercury exposures
estimated from single-day estimates. Exposure (on a per kg/bw basis) among children ages 10 and
younger are elevated compared with adult values. Children in the age range 11 through 14 years have
mercury doses (jjg Hg/kg body weight/day) more comparable to adult values than to those of younger
children. When the NHANES HI data are grouped by age category, exposure patterns shown in Table 4-64
are identified. Higher doses of mercury relative to body weight (ug/kg body weight/day) were also
observed in data from CSFH 94 and CSFH 95 (Table 4-66).
4-79
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Table 4-64
Consumption of Fish and Shellfish (grams/day) and Mercury Exposure (ug Hg/kg bw/day) among
Different Age Categories of Children, Based on Individual Day Data
(Data from the NHANES m, 1988-1994)
Age Group, Years
Less than 2 years
50th Percentile
90th Percentile
95th Percentile
3 through 6 years
50th Percentile
90th Percentile
95th Percentile
7 through 10 years
50th Percentile
90th Percentile
95th Percentile
11 through 14 years
50th Percentile
90th Percentile
95th Percentile
Fish Consumption
grams/day
29
95
115
43
113
151
77
178
270
63
158
215
Mercury Exposure
ug/kg body weight/day
0.33
0.98
1.33
0.28
0.77
1.08
0.31
0.86
1.08
0.15
0.42
0.68
Table 4-65
Fish and Shellfish Consumption (grams/day) and Mercury Exposure (ug/kg body weight/day)
for Children Aged 14 years and Younger CSFII89-91
Based on Average of Three 24-Hour Recalls
Gender
25th
50th
75th
95th
"Per User"
Females
Males
13
0.08
14
0.09
24
0.17
23
0.17
38
0.34
43
0.29
75
0.85
87
0.63
Maximum
Value
154
1.69
139
1.51
"Per Capita"
Females
Males
Zero
Zero
Zero
Zero
Zero
Zero
Zero
Zero
7
Zero
5
0.01
43
0.39
52
0.33
155
1.69
139
1.51
4-80
-------
Table 4-66
"Per User" Fish and/or Shellfish Consumption (grams/day) and
Mercury Exposure (ug Hg/kg bw/day) by Children ages 14 and Younger
Based on Individual Day Data.
Survey
CSFH 94 - Day 1
n=148
CSFH 94 - Day 2
n=162
CSFH 95 - Day 1
n=126
CSFII 95 - Day 2
n=148
NHANES m
1988-1994
n=l,062
10th
15
0.04
16
0.07
16
0.04
13
0.03
14
0.04
50th
53
0.13
53
0.20
57
0.23
53
0.23
51
0.25
90th
127
0.77
156
0.67
185
0.69
170
1.00
155
0.83
95th
176
1.06
171
0.91
204
0.81
243
1.98
185
1.08
Maximum
293
1.56
384
2.70
305
5.93
305
2.63-
915
6.95
Comparison of the "per capita" and "per user" values indicate that Asian Americans and Pacific
Islanders consume fish and shellfish more frequently than other subpopulations. However, the quantity of
fish and shellfish consumed per person is actually smaller than for the other subpopulations Table 4-67).
If mercury exposure is expressed on a body weight basis (ug Hg/kg body weight), the exposures are more
comparable although Asian Americans/Pacific Islanders have lower exposure to mercury (on a body
weight basis) than do other ethnically diverse subpopulations (Table 4-67).
Table 4-67
Consumption of Fish and Shellfish (grams/day) and Mercury Exposure (ug Hg/kg bw/day)
Among Ethnically Diverse Groups, Based on Individual Day Recalls
(Source: CSFII94 and CSFII95)
Ethnic Group
White
50th Percentile
90th Percentile
95th Percentile
Black
50th Percentile
90th Percentile
95th Percentile
Per Capita1
Fish
Consumption
grams/day
Zero
24
80
Zero
48
104
Mercury
Exposure
ftgfkg bw/day
Zero
0.03
0.14
Zero
0.05
0.19
Per User2
Fish
Consumption
grams/day^
72
192
243
82
228
302
Mercury
Exposure
PS/kg bw/day
0.12
0.46
0.67
0.14
0.54
0.96
4-81
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Table 4-67 (continued)
Consumption of Fish and Shellfish (grams/day) and Mercury Exposure (fig Hg/kg bw/day)
Among Ethnically Diverse Groups, Based on Individual Day Recalls
Ethnic Group
Asian and Pacific Islander
50th Percentile
90th Percentile
95th Percentile
Native American and Alaska
Native
50th Percentile
90th Percentile
95th Percentile
Other
50th Percentile
90th Percentile
95th Percentile
Per Capita1
Fish
Consumption
grams/day
Zero
80
127
Zero
Zero
56
Zero
Zero
62
Mercury
Exposure
/ig/kg bw/day
Zero
0.15
0.30
Zero
Zero
0.03
Zero
Zero
0.13
Per User2
Fish
Consumption
grants/day
62
189
292
Estimate not
made because
of small
numbers of
respondents.
83
294
327
Mercury
Exposure
fig/kg bw/day
0.10
0.39
0.56-
Exposures not
made because
of small
numbers of
respondents.
0.18
0.64
0.81
'Total number of 24-hour food consumption recall reports: White (16,241); Black (2,580); Asian and
Pacific Islander (532); Native American and Alaska Native (166): and Other (1,195).
2 Number of 24-hour food consumption recall reports: White (1,821); Black (329); Asian and Pacific
Islander (155); Native American and Alaska Native (12); and Other (98).
4.4.3 Month-Long Estimates for Consumers
The third NHANES included survey questions on the frequency of consumption of fish and
shellfish that permitted nationally based estimates on how frequently people in the general United States
population consume fish and shellfish over a month-long period. The typical frequency of consumption
combined with a "snap shot" of typical consumption on any single day as shown in the "per user" 24-
hour recall data permit projection of moderate-term patterns of fish/shellfish consumption. It is these
moderate-term patterns that are the most relevant exposure period for the health-based endpoint that
formed the basis of the RfD - i.e., developmental deficits in children following maternal exposure to
methylmercury. Additional description of the particular importance of moderate-term patterns of mercury
exposure from fish/shellfish intakes is found in Section 4.1.1 (page 4-1 through 4-3 of this Volume).
The frequency of fish and shellfish consumption can be determined from the food frequency data
obtained in NHANES HI. By combining the number of times per month a person eats fish and shellfish
with the 24-hour recall data that provide an estimate of portion size and species of fish/shellfish selected, a
projection can be made of the consumption pattern over a month. The statistical methods describing how
4-82
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these two frequency distributions were combined is presented in Appendix D. The month-long projection
of fish/shellfish consumption for the general population is shown in Table 4-68a and 4-68b; the estimate
for women of childbearing age (assumed to be 15 through 44 years) is shown in Tables 4-69 and 4-70, and
the estimates for children are shown in Tables 4-71 and 4-72.
Table 4-68a
Month-Long Estimates of Fish and Shellfish Consumption (gins/day)
General Population by Ethnic/Racial Group
National Estimates Based on NHANES III Data
White/NonHispanic
Percentile
50th
75th
90th
95th
Percentile at
which
consumption
equals
approximately
1 00 grams/day.
Fish/Shellfish
gms/day
8
19
44 '
73
97.3th
Percentile
Black/NonHispanic
Percentile
50th
75th
90th
95th
Percentile at
which
consumption
equals
approximately
100 grams/day.
Fish/Shellfish
gms/day
10
25
58
97
95.1th
Percentile
Other
Percentile
50th
75th
90fh
95th
Percentile at
which
consumption
equals
approximately
100 grams/day.
Fish/Shellfish
gms/day
9
27
70
123
94.6th
percentile
Table 4-68b
Month-Long Estimates of Mercury Exposure (fjg/kgbw/day)
Population by Ethnic/Racial Group
National Estimates Based on NHANES III Data
White/NonHispanic
Percentile
50th
75th
90th
95th
Mercury
Exposure
ug/kgbw/day
0.02
0.04
0.09
0.15
Black/NonHispanic
Percentile
50th
75th
90th
95th
Mercury
Exposure
Mg/kgbw/day
0.02
0.05
0.13
0.21
Other
Percentile
50th
75th
90th
95th
Mercury
Exposure
Mg/kgbw/day
0.02
0.06
0.17
0.31
4-83
-------
Table 4-69
Month-Long Estimates of Exposure to Fish and Shellfish (gms/day)
for Women Ages 15 through 44 Years
Combined Distributions Based on NHANES III Data
Percentile
50th
75th
90th
95th
Percentile at which consumption
exceeds approximately 100 grams/day
based on month-long projections
Fish/Shellfish
(gms/day)
9
21
46
77
97th percentile
Table 4-70
Month-Long Estimates of Mercury Exposure (fig/kgfcn'/day) for Women Ages 15 through 44
All Subpopulations Combined
National Estimates Based on NHANES III Data
Percentiles
50th
75th
90th
95th
99th
Mercury Exposure
ug/kgAn'/day
Month-Long Estimates
0.01
0.03
0.08
0.13
0.37
4-84
-------
Table 4-71
Month-Long Estimates of Fish/Shellfish Consumption (gms/day)
among Children Ages 3 through 6 Years.
National Estimates Based on NHANES III Data
Percentile
50th
75th
90th
95th
Per User Month-Long Estimate
Fish/Shellfish Consumption
(grams/day)
5
12
25
39
Mercury Exposure
(ug/kg&M'/day)
0.03
0.08
0.18
0.29
Table 4-72
Month-Long Estimates of Exposure to Fish and Shellfish (gms/day) and
Mercury (pg/kgbw/day) among Children Ages 3 through 6 Years
National Estimates for Individual Ethnic/Racial Groups
Percentile
50th
75th
90th
95th
Fish
(grams/day)
Mercury
(pg/kgbw/day)
Fish
(grams/day)
Mercury
(pgfkgbw/day)
Fish
(grams/day)
Mercury
(ug/kgftw/rfoy)
Fish
(grams/day)
Mercury
(pg/kgbw/day)
All Groups
5
0.03
12
0.08
25
0.18
39
0.29
White/
NonHispanic
5
0.03
11
0.08
24
0.17
37
0.28
Black/
NonHispanic
6
0.03
13
0.08
28
0.19
44
0.33
Other
7
0.04
17
0.11
36
0.25
57
0.42
4-85
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4.4.4 Habitat of Fish Consumed and Mercury Exposure from Fish of Marine. Estuarine and Freshwater
Origin
Fish and shellfish species have been grouped into those inhabiting marine, estuarine, and
freshwater environments. This classification was developed by US EPA's Office of Water based on advise
from fisheries biologists. Categories of fish and shellfish into those primarily inhabiting marine, estuarine,
and freshwater environments was shown in Table 4-17.
State and local authorities frequently have obtained data on mercury concentrations in fish in
waterways within their boundaries. Thirty-eight states in the United States have issued advisories
regarding mercury exposures that will occur through consumption of these fish. Nine states have state-
wide advisories that either are based primarily upon or include concern for mercury exposures from these
fish. At a local level, the mercury concentrations in fish vary widely. Exposures to methylmercury will
vary with the proportion of fish obtained from local sources and from interstate commerce.
Estimates have been made of a national pattern indicating the mixture of marine, estuarine, and
freshwater source of fish and shellfish. Tables 4-73 and 4-74 are based on the fish/shellfish consumption
data from NHANES ITJ combined with the mercury concentration data of the NMFS and data reported by
Bahnick et al. (1988) on mercury concentrations in freshwater fish coming from a nationally based sample
of fish and shellfish. Consumption of fish and shellfish from a particular geographic site may result in
higher or lower exposures to methylmercury.
Among the three habitat types, overall consumption of freshwater fish and shellfish resulted in the
highest mercury exposure per kilogram body weight, followed by marine and estuarine fish and shellfish.
Men reported higher mercury exposures from freshwater fish than did women. The higher external doses
from freshwater fish are, in part, a reflection of larger serving sizes reported when freshwater species are
consumed.
Table 4-73
Exposure of Men Ages 15 to 44 Years to Mercury (fig Hg/kg bw/day)
from Fish and Shellfish of Marine, Estuarine, and Freshwater Origin
Based on Individual Day Recalls
(Food Consumption Data from NHANES III and
Mercury Concentration Data from NMFS and Bahnick et al. (1988))
Statistic
Percentiles
10th
50th
90th
95th
Maximum
Values Reported
Marine
Origin
n=386
0
0.10
0.35
0.60
4.43
Estuarine
Origin
n = 198
0
0.03
0.30
0.44
0.71
Freshwater
Origin
n=60
0.01
0.33
1.26
1.37
1.91
Combined
Origin, i.e., Total
Exposure
n = 644
0.01
0.11
0.44
0.60
4.43
4-86
-------
Table 4-74
Exposure of Women Aged 15-44 Years to
Mercury (ug Hg/kg bw/day) from
Fish and Shellfish of Marine, Estuarine, and Freshwater Origin
Based on Individual Day Recalls
(Food Consumption Data from NHANES ffl and
Mercury Concentration Data from NMFS and Bahnick et al. (1988))
Statistic
Percentiles
10th
50th
90th
95th
Maximum
Reported Value
Marine
Origin
n = 581
0.01
0.10
0.41
0.56
3.59
Estuarine
Origin
n = 221
0.01
0.03
0.14
0.23
0.39
Freshwater
Origin
n = 82
0.04
0.18
0.50
0.77
0.91
Combined
Origin, i.e., Total
Exposure
n = 882
0.01
0.10
0.39
0.53
3.59
4.4.5 Methylmercury Consumption
Quantities of methylmercury consumed in fish depend upon both the quantity offish consumed
and the methylmercury concentration of the fish. Although they are infrequently consumed, swordfish,
barracuda and shark have a much higher methylmercury concentration than other marine finfish,
freshwater finfish or shellfish. By contrast most shellfish contain low concentrations of methylmercury
resulting in far lower methylmercury exposures than would occur if finfish species were chosen.
4.5 Conclusions on Methylmercury Intake from Fish
Methylmercury intakes calculated in this chapter have been developed for a nationally based
population rather than site-specific estimates. Food consumption data was provided from the CSFII 89/91,
CSFn 94, CSFn 95, and NHANES HI surveys. Methylmercury intakes calculated in this chapter have
been developed for a nationally based rather than site-specific estimates. The CSFn 89-91 from USDA
was designed to represent the U.S. population. The concentrations of methylmercury in marine fish and
shellfish were from a data base that is national in scope. Data on freshwater finfish were taken from two
large studies that sampled fish at a number of sites throughout the United States. The extent of
applicability of these data to site-specific assessments must rest with the professional judgments of the
assessor. Because of the magnitude of anthropogenic, ambient mercury contamination, the estimates of
methylmercury from fish do not provide a value that reflects methylmercury from nonindustrial sources.
"Background" values imply an exposure against which the increments of anthropogenic activity could be
added. This is not the situation due to release of substantial quantities into the environment.
Issues dealing with confidence in data on the methylmercury concentration of fish consumed
include the following:
4-87
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In a number of situations individuals cannot identify with accuracy the species of fish
consumed. The USDA Recipe File Data Base has "default" fish species specified if the
respondent does not identify the fish species consumed. There is no way, however to
estimate the magnitude of uncertainty encountered by misidentification of fish species by
the survey respondents.
The data base used to estimate methylmercury concentrations in marine fish and shellfish
was provided by the NMFS. This data base has been gathered over approximately the past
20 years and covers a wide number of species of marine fish and shellfish. The number of
fish samples for each species varies but typically exceeds 20 fish per species.
The analytical quality of the data base has been evaluated by comparison of these data
with compliance samples run for the U.S. FDA. The National Academy of Sciences'
Report on Seafood Safety and the U.S. FDA have found this data base from NMFS to be
consistent with 1990s data on methylmercury concentrations in fish.
The methylmercury concentrations in freshwater fish come from two publications, each
giving data that represent freshwater fish from a number of locations. These data were
gathered between the early 1980s and early 1990s. These surveys by U.S. EPA (1992),
Bahnick et al. (1994), and Lowe et al. (1985) report different mean mercury
concentrations; 0.260 (Jg/g mercury (wet weight) and 0.114 pg/g mercury (wet weight),
respectively. The extent to which either of these data sets represents nationally based data
on freshwater fish methylmercury concentrations remains uncertain.
Month-long estimates of mercury exposure from fish and shellfish consumption are
considered the exposure projection most relevant to the health endpoint of concern; i.e.,
developmental deficits among children following maternal fish consumption.
Because methylmercury is a developmental toxin, a subpopulation of interest is women of
child-bearing age. In this analysis of methylmercury intake, dietary intakes of women
aged 15 through 44 years were used to approximate the diet of the pregnant woman. From
data on Vital and Health Statistics, it has been determined that 9.5% of women of
reproductive age can be anticipated to be pregnant within a given year. Generally food
intake increases during pregnancy (Naismith, 1980). Information on dietary patterns of
pregnant women has been assessed (among other see Bowen, 1992; Greeley et al., 1992).
Most of these analyses have focussed on intake of nutrients rather than contaminants. It is
uncertain whether or not pregnancy would modify quantities and frequency of fish
consumed beyond any increase that may result from increased energy (i.e., caloric) intake
that typically accompanies pregnancy.
Based on available data on fish consumption in the 3 through 6 year age group, it is
estimated that 19 to 26% of these children consume relatively more fish on a per kilogram
per body-weight basis than do adults, which may result in higher mercury exposure these
children. The range reflects differences in mercury exposures between subpopulations
categorized on the basis of race and ethnicity. Persons of Asian/Pacific Islander, non-
Mexican Hispanics (largely persons of Caribbean ethnicity), Native Americans, and
Alaskan Natives have the highest exposures.
Because mercury concentrations in fish/shellfish are highly variable, information on
fish/shellfish consumption (grams/day) are also of interest. It is estimated that 3% of
4-88
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women have month-long fish/shellfish intakes of 100 grams per day and higher based on
the NHANES m data.
4-89
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5. POPULATION EXPOSURES - NON-DIETARY SOURCES
5.1 Dental Amalgams
Dental amalgams have been the most commonly used restorative material in dentistry. A typical
amalgam consists of approximately 50% mercury by weight. The mercury in the amalgam is continuously
released over time as elemental mercury vapor (Begerow et al.> 1994). Research indicates that this
pathway contributes to the total mercury body burden, with mercury levels in some body fluids correlating
with the amount and surface area of fillings for non-occupationally exposed individuals (Langworth et al.,
1991; Olstad et al., 1987; Snapp et al., 1989). For the average individual an intake of 2-20 ug/day of
elemental mercury vapor is estimated from this pathway (Begerow et al., 1994). Additionally, during and
immediately following removal or installation of dental amalgams supplementary exposures of 1-5 ug/day
for several days can be expected (Geurtsen 1990).
Approximately 80% of the elemental mercury vapor released by dental amalgams is expected to
be re-absorbed by the lungs (Begerow et al., 1994). In contrast, dietary inorganic mercury absorption via
the gastrointestinal tract is known the be about 7%. The contribution to the body burden of inorganic
mercury is thus, greater from dental amalgams than from the diet or any other source. The. inorganic
mercury is excreted in urine, and methylmercury is mainly excreted in feces. Since urinary mercury levels
will only result from inorganic mercury intake, which occurs almost exclusively from dietary and dental
pathways for members of the general public, it is a reasonable biomonitor of inorganic mercury exposure.
Urinary mercury concentrations from individuals with dental amalgams generally range from 1-5 ug/day,
while for persons without these fillings it is generally less than 1 ug/day (Zander et al., 1990). It can be
inferred that the difference represents mercury that originated in dental amalgams.
Begerow et al., (1994) studied the effects of dental amalgams on inhalation intake of elemental
mercury and the resulting body burden of mercury from this pathway. The mercury levels in urine of 17
people aged 28-55 years were monitored before and at varying times after removal of all dental amalgam
fillings (number of fillings was between 4-24 per person). Before amalgam removal, urinary mercury
concentrations averaged 1.44 ug/g creatinine. In the immediate post-removal phase (up to 6 days),
concentrations increased by an average of 30%, peaking at 3 days post-removal. After this phase mercury
concentrations in urine decreased continuously and by twelve months had dropped to an average of 0.36
ug/g creatinine. This represents a four-fold decrease from pre-removal steady-state urinary mercury levels.
5.2 Occupational Exposures to Mercury
Industries in which occupational exposure to mercury may occur include chemical and drug
synthesis, hospitals, laboratories, dental practices, instrument manufacture, and battery manufacture
(National Institute for Occupational Safety and Health, (NIOSH) 1977). Jobs and processes involving
mercury exposure include manufacture of measuring instruments (barometers, thermometers, etc.),
mercury arc lamps, mercury switches, fluorescent lamps, mercury broilers, mirrors, electric rectifiers,
electrolysis cathodes, pulp and paper, zinc carbon and mercury cell batteries, dental amalgams, antifouling
paints, explosives, photographs, disinfectants, and fur processing. Occupational mercury exposure can
also result from the synthesis and use of metallic mercury, mercury salts, mercury catalysts (in making
urethane and epoxy resins), mercury fulminate, Millon's reagent, chlorine and caustic soda,
Pharmaceuticals, and antimicrobial agents (Occupational Safety and Health Administration (OSHA)
1989).
OSHA (1975) estimated that approximately 150,000 US workers are exposed to mercury in at
least 56 occupations (OSHA 1975). More recently, Campbell et al., (1992) reported that about 70,000
5-1
-------
workers are annually exposed to mercury. Inorganic mercury accounts for nearly all occupational
exposures, with airborne elemental mercury vapor the main pathway of concern in most industries, in
particular those with the greatest number of mercury exposures. Occupational exposure to methylmercury
appears to be insignificant. Table 3-10 summarizes workplace standards for airborne mercury (vapor +
paniculate).
A number of studies have been reported that monitored workers' exposure to mercury (Gonzalez-
Fernandez et al., 1984; Ehrenberg et al., 1991; Cardenas et al., 1993; Kishi et al., 1993,1994; Yang et al.,
1994). Some studies have reported employees working in areas which contain extremely high air
mercury concentrations: 0.2 to over 1.0 mg/m3 of mercury. Such workplaces include lamp sock
manufacturers in Taiwan (Yang et al., 1994), mercury mines in Japan (Kishi et al., 1993,1994), a small
thermometer and scientific glass manufacturer in the US (Ehrenberg et al., 1991), and a factory producing
mercury glass bubble relays (Gonzalez-Fernandez et al., 1984). High mercury levels have been reported
in blood and urine samples collected from these employees (reportedly over 100 ug/L in blood and over
200 - 300 ug/L or 100 - 150 ug/g creatinine for urine). At exposures near or over 1.0 mg/m3, workers
show clear signs of toxic mercury exposure (fatigue, memory impairment, irritability, tremors; and mental
deterioration). The chronic problems include neurobehavioral deficits that persist long after blood and
urine mercury levels have returned to normal; many workers required hospitalization and/or drug
treatments. With the exception of mercury mines, workplaces producing these mercury levels are typically
small and specialized, often employing only a few workers who were exposed to high mercury
concentrations.
Many other studies have monitored employees' work areas and reported measured mercury air
concentrations of 0.02 - 0.2 mg/m3; these levels are generally in excess of present occupational standards
(see Table 5-1). These mercury levels were most often reported at chlor-alkali plants (Ellingsen et al.,
1993; Dangwal 1993; Barregard et al., 1992; Barregard et al., 1991; Cardenas et al., 1993). Employees at
these facilities had elevated bodily mercury levels of approximately 10-100 ug/L for urine and about 30
ug/L in blood. At these lower levels, chronic problems persisting after retirement included visual response
and peripheral sensory nerve effects.
Exposures to mercury levels under 0.02 mg/m' typically result in blood and urine levels
statistically higher than the general population, but health effects are usually not observed.
Table 5-1
Occupational Standards for Airborne Mercury Exposure
Concentration
Standard (mg/m3)
0.10
0.01
0.03
0.05
0.01
Standard Type
STEL
TWA
STEL
TWA
TWA
Mercury Species
inorganic
organic
alkyl
all besides alkyl
alkyl
Reference
CFR(1989)
CFR(1989)
CFR(1989)
ACGIH (1986)
ACGIH (1986)
5-2
-------
Table 5-1 (continued)
Occupational Standards for Airborne Mercury Exposure
Concentration
Standard (mg/m3)
0.03
0.10
0.05
Standard Type
STEL
TWA
TWA
Mercury Species
alkyl
aryl and inorganic
all besides alkyl
Reference
ACGIH (1986)
ACGIH (1986)
NIOSH(1977)
Abbreviations:
ACGIH - American Conference of Governmental Industrial Hygienists
CFR - Code of Federal Regulations
STEL - Short term exposure limit (15 minutes)
TWA - Time weighted average (8 hour workday)
5.3 Miscellaneous Sources of Mercury Exposure
Inorganic mercury is used in some ritualistic practices (Wendroff, 1995). The extent of this use in
the United States is undocumented, although it is considered to be more commonly encountered in
Hispanic and Latino communities. Inorganic mercury is distributed around the household in a variety of
ways and may result in dermal contact or it potentially be inhaled.
5.4 Cases of Mercury Poisoning
Numerous examples may be found in the literature of unintentional mercury poisoning. The
following examples were taken from Morbidity and Mortality Weekly Report, a publication of the U.S.
Public Health Service, Centers for Disease Control. These cases studies indicate that mercury has diverse
although, in many cases, illegal applications. The studies illustrate the wide range of potential health
effects from mercury exposure including death.
Unsafe Levels of Mercury Found in Beauty Cream
Between September 1995 and May 1996, the Texas Department of Health, the New Mexico
Department of Health, and the San Diego County Health Department investigated three cases of mercury
poisoning associated with the use of a mercury-containing beauty cream produced in Mexico. The cream,
marketed as "Crema de Belleza-Manning" for skin cleansing and prevention of acne, has been produced
since 1971. The product listed "calomel" (mercurous chloride) as an ingredient and contained 6% to 10%
mercury by weight. Because mercury compounds are readily absorbed through the skin, FDA regulations
restrict the use of these compounds as cosmetic ingredients. Specifically, mercury compounds can be tzsed
only as preservatives in eye-area cosmetics at concentrations not exceeding 65 ppm of mercury; no
effective and safe nonmercurial substitute preservative is available for use in such cosmetics.
An ongoing investigation of the cream located it in shops and flea markets in the United States
near the U.S.-Mexico border, and identified a U.S. organization in Los Angeles as the distributor. Media
announcements, warning of the mercury containing cream, were then made in Arizona, California, New
Mexico, and Texas. In response to these announcements, 238 people contacted their local health
5-3
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departments to report using the cream. Urinalysis was conducted for 119 people, and of these, 104 had
elevated mercury levels. Elevated urine mercury levels were also detected in people who did not use the
cream but who were close household contacts of cream users.
Indoor Latex Paint Found to Contain Unsafe Mercury Levels
In August 1989, a previously healthy 4-year-old boy in Michigan was diagnosed with acrodynia, a
rare manifestation of childhood mercury poisoning. A urine mercury level of 65 jig/L was measured in a
urine sample collected over 24 hours. Examinations of his parents and two siblings also revealed elevated
urine mercury levels. The Michigan Department of Public Health (MDPH) determined that inhalation of
mercury-containing vapors from phenylmercuric acetate contained in latex paint was the probable route of
mercury exposure for the family; 17 gallons of the paint had been applied to the inside of the family's
home during the first week of July. During that month, the air conditioning was turned on and the
windows were closed, so that mercury vapors from the paint were not properly vented. In addition,
samples of the paint contained 930-955 mg/L mercury, while the EPA limit for mercury as a preservative
in interior paint is 300 mg/L.
In October, the Michigan Department of Agriculture prohibited further sales of the inappropriately
formulated paint, and the MDPH advised people not to use the paint, to thoroughly ventilate freshly
painted areas, and to consult a physician if unexplained health problems occurred. In November, the
MDPH and Centers for Disease Control began an ongoing investigation in selected communities in
southeastern Michigan to assess mercury levels in the air of homes in which this paint had been applied
and in urine samples from the occupants.
Jar of Mercury Spilled in Ohio Apartment
In November 1989, a 15-year-old male from Columbus, Ohio was diagnosed with acrodynia, a
form of mercury poisoning. A 24-hour urine collection detected a mercury level of 840 ug/L in the
patient's urine. The patient's sister and both his parents were also found to have elevated mercury urine
levels. Therefore, on November 29, the Columbus Health Department investigated the apartment where
the family had lived since August 26, 1989. Neighbors reported that the previous tenant had spilled a large
jar of elemental mercury within the apartment. Mercury vapor concentrations in seven rooms ranged from
50-400 pg/m3. The Agency for Toxic Substances and Disease Registry's acceptable residential indoor air
mercury concentration is less than or equal to 0.5 ug/m3.
Mercury Vapors Released in House During Smelting Operation
On August 7,1989, four adults from Michigan, ranging from age 40 to 88, were hospitalized for
acute mercury poisoning. All four patients lived in the same house, where one of the patients had been
smelting dental amalgam in a casting furnace in the basement of the house in an attempt to recover silver.
Mercury fumes were released during the smelting operation, entered air ducts in the basement, and were
circulated throughout the house. All four patients died of mercury poisoning within 11-24 days after
exposure.
Mercury Spilled in Michigan House
During the summer of 1989, a boy in Michigan spilled about 20 cm3 of liquid mercury in his
bedroom. In September of that year, both of his sisters were diagnosed with mercury poisoning, after
exhibiting clinical symptoms associated with such poisoning. The boy, although asymptomatic, was also
tested and was found to have elevated mercury levels.
5-4
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Florida School Children Find Elemental Mercury in Abandoned Van
During August 1994, five children residing in a neighborhood in Palm Beach County, Florida
found 5 pints of elemental mercury in an abandoned van. During the ensuing 25 days, the children shared
and played with the mercury outdoors, inside homes, and at local schools. On August 25,1994, a parent
notified local police and fire authorities that her children had brought mercury into the home. That same
day, 50 homes were immediately vacated and an assessment of environmental and health impacts was
initiated by the State of Florida Department of Environmental Protection, the Health and Rehabilitation
Services of the Palm Beach County Public Health Unit, and the U.S. Environmental Protection Agency.
A total of 58 residential structures were monitored for indoor mercury vapor concentrations;
unsafe indoor air levels of mercury (>15 ug/m3) were detected in 17. Several classrooms at the local high
schools were determined to be contaminated. In addition, 477 people were identified by the survey as
possibly exposed to mercury vapors and were evaluated at the emergency department of the local hospital
or the health department clinic for mercury poisoning. Of these people, 54 were found to have elevated
mercury levels.
Unsafe Mercury Levels Found in North Carolina Home
In July 1988, the Environmental Epidemiology Section of the North Carolina Department of
Environment, Health, and Natural Resources (DEHNR), investigated chronic mercury poisoning diagnosed
in a 3-year-old boy from North Carolina. Results of 24-hour urine specimens for mercury collected from
both the patient and his parents revealed elevated mercury levels. Although the family reported no known
mercury exposures, in April 1988, they had moved into a house whose previous owner had collected
elemental mercury. Several containers of mercury had reportedly been spilled in the house during the
previous owner's occupancy. As a result of the determination that the house was the probable source of
exposure, the family temporarily relocated.
The DEHNR conducted an extensive investigation of the house. Elevated mercury levels were
detected in five rooms and two bathrooms. The vacuum cleaner filter bag was tested for mercury as well,
and found to have extremely high mercury levels. The carpets were also heavily contaminated with
mercury. When the contaminated carpets were vacuumed, mercury particles and vapor were probably
dispersed throughout the house. Vaporization probably increased with the spread of the mercury and the
onset of warmer weather.
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6. COMPARISON OF ESTIMATED EXPOSURE WITH BIOMONITORING
6.1 Biomarkers of Exposure
Biologic markers, as described by the U.S. National Research Council (NRC, 1989) are indicators
signaling events in biological systems or samples. These are classified as biologic markers of exposure.
effect and susceptibility. A biological marker of exposure is defined by the National Research Council
(1989) an "exogenous substance or its metabolite(s) or the product of an interaction between a zenobiotic
agent and some target molecule or cell that is measured in a compartment within an organism" (NRC,
1989, pg. 2). Concentrations of mercury and of methylmercury in biological materials are used as
biomarkers of exposure to mercury in the environment
Mercury accumulates in body organs. Although concentrations of mercury in organs adversely
affected by mercury (e.g., neural tissue, the kidney) may be more predictive of levels of exposure at the site
of organ system damage, for purposes of monitoring exposures mercury concentrations in tissues less
proximal are relied upon. Typically mercury concentrations in blood, hair, and urine are used to assess
exposure to organic and inorganic mercury.
6.2 Biomarkers of Exposure Predictive of Intake of Methylmercury
Humans are exposed to both organic (e.g., methylmercury) and inorganic mercury. The proportion
of organic to inorganic mercury exposure depends on exposure conditions. Organic methylmercury almost
exclusively occurs through consumption of fish and shellfish. Occupational exposure to organic mercury
compounds is far less common than are occupational exposures to inorganic mercury compounds. Within
occupations where exposures to organic mercury compounds occur, great caution must be taken to assure
that people handling such compounds do not come into contact with organic mercury because of its
extreme toxicity. Inorganic mercury exposures reflect sources including dental amalgams and occupational
sources with minor contributions from certain hobbies and ritualistic uses of mercury. Contribution from
"minor" sources refers to their overall use in the general population. Such "minor" sources can produce
highly elevated exposures and poisoning of individuals who use these products.
Blood and hair concentrations of mercury can be used to back calculate estimates of
methylmercury ingested. Because methylmercury in the diet comes almost exclusively from consumption
of fish and shellfish, methylmercury concentrations in blood and hair are very strong predictors of
methylmercury ingestion from fish and shellfish.
The fraction of methylmercury absorbed via the gastrointestinal tract from fish and shellfish is
extremely high; typically more than 95% (REFS). After absorption methylmercury is transported in the
blood. There is a strong affinity for the erythrocyte (Aberg et al., 1969; Miettinen, 1971). Standard
reference values for blood mercury concentrations indicate packed cells are 10-times more concentrated in
mercury than is whole blood (Cornelis et al., 1996). Methylmercury is distributed throughout the body
including distribution into the central nervous system. Postabsorption and distribution to tissues,
methylmercury is slowly demethylated and converted to inorganic mercury (Burbacker and Mottet, 1996).
A portion of the inorganic mercury arising from demethylation of methylmercury is present in
blood (Smith and Farris, 1996). Additional sources of inorganic mercury include dental amalgams in
persons with silver-mercury dental restorations, small amounts of inorganic mercury absorbed from diet,
and for some individuals occupational and/or miscellaneous sources. Although inorganic mercury is
present in blood, under most conditions the predominant chemical species of mercury in blood is
methylmercury arising from consumption offish and shellfish.
6-1
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6.3 Sample Handling and Analysis of Blood Samples for Mercury
The predominant method of chemical analysis of total mercury in blood is based on cold vapor
absorbance techniques (IUPAC, 1996; Nixon et al., 1996). Atomic fluorescence is also a very sensitive
and reliable technique for mercury measurement in blood, serum and urine (IUPAC, 1996). The various
mercury-species are converted by reducing agents to elemental mercury and released as a vapor which is
either directly pumped through the cell of the atomic absorption spectrophotometer or analyzed after
amalgamation and enrichment on gold (IUPAC, 1996).
Sample pretreatment to destroy the organic matter in samples and avoid losses of mercury through
volatilization are key considerations in the analytic procedure for determination of inorganic and total
mercury. Digestion procedures have been developed that permit conversion of organic mercury
compounds and arylmercury to inorganic mercury, but do not convert significant quantities of
alkylmercury (i.e., methylmercury) to inorganic mercury (Nixon et al., 1996).
The expected concentration cited by IUPAC (1996) for mercury in serum of healthy individuals is
0.5 ug/L. In packed cells the level is about 5 ug/kg. Standard reference materials for mercury in whole
blood are available in the range of 4 to 14 ug/L. Using the IUPAC (1996) expected concentration, whole
blood mercury would be less than 2.5 ug/L.
Sample handling prior to analysis is always critical in obtaining optimal analytical results. The
Commission of Toxicology of the IUPAC has described an organized system for collection and handling of
human blood and urine for the analysis of trace elements including mercury (1996).
6.4 Association of Blood Mercury with Fish Consumption
6.4.1 Half-Lives of Methylmercury in Blood
The half-life of mercury in blood varies with prior intake of methylmercury and individual
characteristics. Previous investigations with methylmercury ingestion under controlled conditions provide
estimates of half-lives among adults. Data on half-lives among children do not appear to exist. Two
studies among adults are particularly informative. Sherlock et al. (1984) evaluated half-lives for
methylmercury ingested via halibut by 14 adult male and 7 adult female volunteers over a period of 96
days. Overall, the half-life for mercury in blood was calculated by Sherlock et al. as 50±1 days
(mean±standard error; range 42 to 70 days) for adult subjects. Another approach is that used by Birke et
al. (1972) based on repeated blood sampling of subjects after termination of chronic ingestion at higher
levels of methylmercury consumption. Data from the study of Birke et al. (1972) showed two subjects
with half-lives of 99 and 120 days in blood cells and 47 and 130 days in plasma. Additional data on half-
lives of methylmercury ingested via fish were reported by Miettinen et al. (1971) following single
ingestion of radiolabelled fish. Miettinen et al. (1971) using ^Hg-labelled methylmercury incorporated
into burbot (Lota vulgaris) fed as a single dose to 15 adult volunteers determined a mean biological half-
time of 50±7 days (mean±standard deviation of the mean) in red blood cells for five male subjects and one
female subject.
Overall the metabolic data support the use of blood mercury as an indicator of recent
methylmercury intake. The range surround mean half-lives reflect the combined influence of individual
person-to-person characteristics, previous intake of methylmercury, and level of methylmercury ingestion.
During the 1990s, a number of additional reports on total blood mercury and on organic methylmercury in
blood have confirmed that higher intakes of fish/shellfish are associated with increasing concentrations of
total mercury, and in particular a higher fraction of methylmercury (Mahaffey and Mergler, in press).
6-2
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6.4.2 Fraction of Total Blood Mercury that Is Organic or Methvlmercurv
Among subjects with blood total mercury levels less than 5 ug/L, Oskarsson et al. (1996) reporting
on 30 women living in northern Sweden found that 26% of blood mercury was organic mercury. By
contrast women who consumed large amounts of seafood had 80% organic mercury at delivery in maternal
blood from Inuit women in Greenland (Hansen et al., 1990), and approximately 83% organic mercury in
Faroese women (Grandjean et al., 1992). High blood levels of total mercury were reported by Akagi et al.
(1995) among residents of the Amazon. In fishing villages where blood total mercury levels were
approximately 100 ug/L, 98% of total mercury was organic (methyl) mercury. Aks et al. (1995) in another
study of adult Amazon villagers, found approximately 90% of total mercury to be organic mercury when
blood levels were approximately 25 to 30 ug/L. Mahaffey and Mergler (in press) found that there was a
linear increase (when the data were log transformed) in the fraction of total blood mercury that was present
as organic mercury over a blood total mercury up to 70 ug/L.
6.4.3 Methvlmercurv Consumption from Fish and Blood Mercury Values
Increasing frequency of fish consumption is predictive of higher total blood mercury
concentrations; particularly increased concentrations of organic mercury (i.e., methylmercury) in blood
(Brune et al., 1991; Hansen et al., 1990; Svensson et al., 1992; Weihe et al., 1996). Within the non-
occupationally mercury exposed population, frequency, quantity and species of fish consumed produce
differences in methylmercury ingestion and in blood mercury concentrations. Brune et al. (1991) reviewed
the literature on total mercury concentrations in whole blood and associated these with the number of fish
meals/week (Table 6-1). Although there is a clear increase in mean values with increasing frequency of
fish consumption, the ranges of values (e.g., 10th and 90th percentiles) overlap with the next highest
.category of consumption. These ranges illustrate some of the difficulty of characterizing methylmercury
intake simply by the reports describing number of fish meals consumed per week.
Table 6-1
Literature Derived Values for Total Mercury Concentrations in Whole Blood
(from Brune et al., 1990)
Level of Fish
Consumption
Category I, No Fish
Consumption
Category II, < 2 Fish
Meals/Week
Category III, * 2-4 Fish
Meals/ Week
Mean Value
20
4.8
8.4
10th and 90th
Percentiles
0,4.3
2.4, 7.2
2.6, 14.2
25th and 75th
Percentiles
0.8, 3.2
3.5, 6.1
5.4, 11.4
Number of
Observations
223
339
658
6-3
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Table 6-1 (continued)
Literature Derived Values for Total Mercury Concentrations in Whole Blood
(from Brune et al., 1990)
Level of Fish
Consumption
Category IV, > 4 Fish
Meals/Week
Category V, Unknown
Fish Consumption
Mean Value
44.4
5.8
10th and 90th
Percentiles
6.1,82.7
1.2, 10.4
25th and 75th
Percentiles
24.4, 64.4
3.4, 8.2
Number of
Observations
613
3182
The analysis by Brune et al. (1990) demonstrated the limitations of determining a methylmercury
intake based on the number of fish meals/week. Nonetheless there is an association between frequency of
fish meals and blood mercury levels. If the exposure analysis is further refined to include a description of
the size of the serving offish consumed, and information on the mercury content of the fish, the
association with blood mercury concentration is strengthened.
6.4.4 North American Reports on Blood Mercury Concentrations
6.4.2.1
United States
Normative data to predict blood mercury concentrations for the United States population are not
available. With a very few exceptions all of the data that have been identified are for adult subjects. The
largest single study appears to be that of former United States Air Force pilots. Kingman et al. (Kingman
et al., in press; Nixon et al., 1996) analyzed urine and blood levels among 1127 Vietnam-era United States
Air Force pilots (all men, average age 53 years at the time of blood collection ) for whom extensive dental
records were available. Blood values were determined for total mercury, inorganic mercury and
organic/methylmercury. Mean total blood mercury concentration was 3.1 ug/L with a range of "zero" (i.e.,
detection limit of 0.2) to 44 ug/L. Overall, 75% of total blood mercury was present as
organic/methylmercury. Less than 1 % of the variability in total blood mercury was attributable to variation
in the number and size of silver-mercury amalgam dental restorations. Dietary data on the former pilots
were very limited, so typical patterns of fish consumption are not reported.
Additional North American studies have been reported by various individual states in the United
States. These are described below and summarized in Table 6-2.
Arkansas
The Arkansas Department of Health reported on total blood mercury for 236 individuals with a
mean of 10.5 (jg/L (range "zero" to 75 ug/L) (Burge and Evans, 1996). Of these, 139 participants had
total blood mercury above 5 ug/L and 36 participants had blood mercury concentrations more than 20
ug/L. To have been included in the survey, subjects had to confirm that their fish consumption rate was a
minimum of two meals per month with eight ounces of fish per meal.
6-4
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Table 6-2
Blood Mercury Concentrations Values Reported for the United States
Study
Burge and Evans
(1996)
Centers for Disease
Control (1993)
Gerstenberger et al.
(1997)
Harnlyetal. (1997)
Community
236 participants
from Arkansas
Micousukee Indian
Tribe of South
Florida. 50 blood
samples from
subjects with mean
age=34 years
(Range 8 to 86
years).
68 Ojibwa Tribal
members from the
Great Lakes Region
Native Americans
living near Clear
Lake, California.
Group studied
include 44 Tribal
members, and 4
nontribal members.
Measure of
Central
Tendency
Mean: 10.5 ug/L;
among men: 12.8
ug/L; among
women, 6.9 ug/L.
Median: All
subjects 7.1 ug/L
Men: 9.0 ug/L
Women: 4.8 ug/L
Mean: 2.5 ug/L
Median: 1.6 ug/L
57 participants < 16
ug/L. Remaining
1 1 subjects
averaged 37 ug/L.
Mean for 44 Tribal
members: 18.5 ug/L
(2.9 ug/L inorganic
Hg + 15.6 ug/L for
organic Hg).
Mean for 4
nontribal members:
11. 5 ug/L (2.7 ug/L
inorganic + 8.8
ug/L organic Hg).
Maximum
All subjects: 75
Mg/L
Males: 75 ug/L
Females: 27 ug/L.
13.8 ug/L
53 ug/L
Among Tribal
members: Total Hg
was 43.5 ug/L (4.7
ug/L inorganic +
38.8 ug/L organic).
For nontribal
members: Total Hg
15.6 ug/L (3.4 ug/L
inorganic + 12.2
ug/L organic).
Additional
Information on
Study
139 participants
exceeded 5 ug/L.
30 participants in
the range of 20 to
75 ug/L or 15%
>20 ug/L.
5% of men had >30
ug/L. No -women
had values > 30
ug/L.
1 1 individuals had
blood mercury in
the range 20 to 53
Mg/L.
20% of all
participants (9
persons including
four women of
childbearing age)
had blood mercury
concentrations £ 20
Mg/L.
6-5
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Table 6-2 (continued)
Blood Mercury Concentrations Values Reported for the United States
Study
Humphrey and
Budd(1996)
Knobeloch et al.
(1995)
Schantz et al.
(1996)
Community
Lake Michigan
residents studied in
1971.
Family consuming
commercially
obtained seafood.
Adult men and
women aged 50 to
90 years. Michigan
residents.
Measure of
Central
Tendency
Algonac, Lake St.
Clair:
Fisheaters (n=42)
mean 36.4
compared with 65
low fish consumers
having mean of 5.7
Mg/L-
South Haven, Lake
Michigan with
lower Hg
contamination.
Fisheaters (n=54)
had mean 1 1 .8 ug/L
and the comparison
group of low fish
consumers mean
(n=42)of5.2ug/L
Initial blood values
for wife (37 ug/L)
and husband (58
ug/L) following
regular
consumption of
imported seabass
having mercury
concentrations
estimated at 0.5 to
0.7 ppm Hg.
104 fisheaters:
mean=2.3 ug Hg/L
84 nonfisheaters:
mean=l.l ugHg/L.
Maximum
Algonac, Lake St.
Clair
Fisheaters: 3.0-95.6
ug/L
Comparison:
1.1 -20.6 Mg/L
South Haven, Lake
Michigan
Fisheaters: 3.7-44.6
ug/L
Comparison:
1.6-1 1.5 Mg/L
Six months after
family stopped
consuming seabass,
blood mercury
concentrations for
the wife (3 ug/L)
and husband (5
ug/L) had returned
to "background"
concentrations.
Maximum for
fisheaters: 20.5 ug
Hg/L
Maximum for
nonfisheaters: 5.0
MgHg/L.
Additional
Information on
Study
Mercury
contamination less
intense in South
Haven compared
with Algonac.
-
Questionnaire on
fish-eating patterns
included sport-
caught Great Lakes
fish and purchased
fish, as well as
questions on
patterns of wild
game consumption.
6-6
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Great Lakes Region
Schantz et al. (1996) reported on blood mercury levels in an older-adult population (ages 50 to 90
years). Blood mercury levels for non-fisheaters averaged 1.1 ug/L and for fish-eaters the average was 2.3
Gerstenberger et al. (1997) determined blood mercury levels for 57 Ojibwas Tribal Members from
the Great Lakes Region. Among the 68 participants 57 had blood mercury concentrations < 16 ug/L. The
remaining 1 1 subjects had average blood mercury concentrations of 37 ug/L with a maximum value of 53
Wisconsin
Blood mercury levels among 175 Wisconsin Chippewas Indians who consumed fish from northern
Wisconsin lakes that have fish with high mercury concentrations (>1 ppm) were determined (Peterson et
al., 1994). Values ranged from nondetectable (i.e., < 1 ug/L) to a high of 33 ug/L. Twenty percent (64
individuals) had blood mercury levels > 5 ug/L. Recent consumption of the fish, walleye, was associated
with elevated blood mercury concentrations.
Knobeloch et al. (1995) investigated mercury exposure in a husband and wife and their two-year-
old son living in Wisconsin. The individuals had total blood mercury ranging from 37 to 58 ug/L. The
family's diet included three to four fish meals per week. The fish was purchased commercially from a
local market. Seabass were found to contain mercury at 0.5 to 0.7 ppm. Six months after the family
stopped consuming the seabass, blood mercury levels in this man and women declined dramatically to 5
and 3 ug/L, respectively.
California
Hamly et al. (1997) determined blood mercury concentrations for 44 members of Native American
tribes and 4 nontribal members living near Clear Lake, California. The mean for the 44 tribal members
was 18.5 ug/L total mercury (15.6 ug/L organic and 2.9 ug/L inorganic). The maximum value was 43.5
ug/L (38.8 ug/L organic and 4.7 ug/L inorganic). Twenty percent of all participants (including four
women of childbearing age) had blood mercury concentrations £ 20 ug/L. Among nontribal members total
mercury concentrations were lower with a total mercury value of 1 1.5 (8.8 organic + 2.7 inorganic) ug/L.
The highest value for nontribal members was 15.6 (12.2 organic and 3.4 inorganic) ug/L.
Florida
The U.S. Centers for Disease Control (CDC, 1993) conducted a community survey of the tribal
.representatives of the Miccousukee Indian Tribe living in South Florida. Blood mercury levels were
determined for 100 participants who were adult tribal members. Fish consumption among this group was
low with a maximum of approximately 170 grams/day and 3.5 grams calculated as a daily average. Total
blood mercury ranged from 0.2 to 13.8 ug/L with median and mean values of 1.6 and 2.5 Mg/L,
respectively. There was a correlation between blood mercury levels and consumption of locally caught
fish.
Maine
An additional source of data on blood mercury levels is the heavy metal profiles (for lead, arsenic,
cadmium, and mercury) conducted as part of occupational surveillance. Typically the persons who receive
6-7
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this type of screening are expected to have exposures to at least one of these metals. Occupational
surveillance may be based on state requirements or Federal statutes. For example, the State of Maine has
an occupational disease reporting requirement on individuals whose blood mercury concentrations for total
mercury are 5 ug/L and higher and whose urinary total mercury is greater than or equal to 20 ug/L. The
State of Maine evaluated data on occupational screening for heavy metal exposure and identified a group
of adults having total blood mercury concentrations more than 5 ppb. Several cases of elevated blood
mercury concentrations were identified. One case has been reported by Dr. Allison Hawkes (personal
communication, 1997). The individual was identified with a blood mercury of 21.4 ug/L. The subject had
no known occupational exposure to mercury, but self-reported eating 3 or 4 fish meals per week. The
individual was asked to abstain from consuming fish for 4 or 5 weeks and then return for follow-up blood
testing. On retesting blood total mercury was only 5 ug/L.
6.4.2.1 Canadian
As in the United States, normative data for the general population of Canada have not been
identified in compiling information for this Report to Congress. By contrast to the United States,
information on mercury exposures in the northern regions of the country has been obtained. The
Department of Indian and Northern Affairs of the Government of Canada reported on Arctic contaminants
in the Canadian Arctic Contaminants Assessment Report in 1997. Methylmercury levels in blood since
1970. For all Aboriginal Peoples the mean blood mercury concentration was 14.13 (standard deviation
22.63) and a range of 1 to 660 ug/L (Wheatley and Paradis, 1995) based on 38,571 data points from 514
native communities across Canada.
Overall, blood mercury concentrations are considered closely tied to consumption of fish and
marine mammals. The highest levels are found among Aboriginal residents with particular high levels
found in northern Quebec and among the northern and eastern Inuit communities. No downward trend
was evident in Inuit blood mercury concentrations between 1975 and 1987, but more recent data (1992 to
1995) indicated lower levels of mercury in some groups (Jensen et al., 1997, page 336).
Quebec
Within the values reported in the Canadian Arctic Contaminants Assessment Report (Jensen et
al., 1997) particularly high mean concentrations were observed among the Inuit (Nunavik) of Quebec.
Mean total mercury concentration of 47 ug/L (SD 33, range 3 to 267 ug/L) was identified among 1114
Inuit of Quebec. The Northern (Cree) had mean values of 34 (SD 41, range 2 to 649 ug/L) among 4,670
blood values and 42.9 (SD 52, range 2 to 649) based on 1,129 blood values.
North West Territory
The Nunavut (Inuit) of the North West Territory also have elevated blood mercury levels with
mean values during the 1970s through late 1980s averaging between 17 and 40 ug/L (upper extent of this
range going to 226 ug/L). The Western (Dene) population had lower blood mercury levels with means
between' 11 and 17 ug/L (upper extent of the Dene range to 138 ug/L).
6.5 Hair Mercury as a Biomarker of Methylmercury Exposure
6.5.1 Hair Composition
Hair is approximately 95% proteinaceous and 5% a mixture of lipids, glycoproteins, remnants of
nucleic acids, and in the case of pigmented hairs, of melanin and phaeomelanin. Hair contains a central
6-8
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core of closely packed spindle-shaped cortical cells, each filled with macrofibrils which in turn consist of a
microfibril/matrix composite. The long axes of the cells and their fibrous constituents are oriented along
the long axis of the hair. The amino acid composition of hair is high in those amino acids with side-chains
(particularly, those containing "reactive" groups such as cystine, cysteine, tyrosine, tryptophan, acidic and
basic amino acids, as well as terminal carboxyl or amino groups). The cortical core is covered by sheet-
like cells of the cuticle. The surfaces of all the cells of the hair shaft have a thin layer of lipid which is
covalently attached to the underlying proteins.
Hair has been assumed to grow at the rate of one centimeter a month (Kjellstrom et al., 1989;
Marsh et al., 1980). However, there is variability in the rate of hair growth. Growth determined
experimentally is between 0.9 and 1.3 cm per month (Barman et al., 1963; Munro, 1966; and Saitoh,
1967).
Mercury is incorporated into hair during the growth of hair. Hair mercury concentrations are
presumed to reflect blood mercury concentrations at the moment of hair growth. Whether the predominant
chemical species is inorganic mercury or methylmercury depends on exposure patterns and on the extent of
demethylation of methylmercury. Hair mercury (ug/g) and blood mercury (ng/L) ratios range from 190:1
up to 370:1 (Skerfving, 1974; Phelps et al., 1980; Turner et al., 1980; Sherlock et al., 1984). Higher ratios
have recently been reported. Additional discussion of the hair to blood mercury ratio is found in the
volume on human health. This is one source of person-to-person variability considered in selection of
uncertainty factors in determining U.S. EPA's Reference Dose for methylmercury.
Chemical analyses to determine mercury concentrations in hair determine total mercury rather than
chemical species of mercury. In order to dissolve hair samples, they must be put through an acid digestion.
The process of acid digestion will convert virtually all of the mercury in the biological sample to inorgank
mercury (Nixon et al., 1996). Consequently the fraction of hair mercury that is methylmercury is only an
estimate based on what is known of environmental/occupational exposure patterns.
The frequency of fish consumption has been used as a guide to differences in hair mercury
concentrations (Airey, 1983). Within a general population as fish consumption increases, hair mercury
concentration will also increase. However, the amount of mercury in hair depends on the concentration of
mercury present in fish consumed. Comparison of recent studies from Bangladesh (Holsbeek et al., 1996)
and Papua New Guinea (Abe et al., 1995) illustrates these differences. Holsbeek et al. (1996) found a
highly significant positive correlation (r=0.88, P<0.001) between fish consumption and hair mercury
concentrations. Total hair mercury concentrations had a mean value of 0.44±0.19 ug/g (range 0.02 to
0.95) and a fish consumption of 2.1 kg/month (range 1.4 to 2.6). The low concentrations in hair reflect tfie
low concentrations of methylmercury in Bangladesh fish. Abe et al. (1995) evaluated 134 fish-consuming
subjects and 13 nonfish-eating subjects in Papua, New Guinea. Among the fish consumers hair mercury
levels had a mean mercury concentrations of 21.9 ug/g (range 3.7 to 71.9). Average fish consumption was
280 grams/day (range=52 to 425) or about 8.4 kg/month producing an average methylmercury intake of 84
ug/day. Among the nonfish consumers the mean hair mercury was 0.75±0.4 ug/g. The difference in hair
mercury concentration in Bangladesh and New Guinea were considerably greater than the differences in
fish mercury.
6-9
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6.5.2 Hair Mercury Concentrations in North America
6.5.2.1 United States
Data do not exist describing hair mercury concentrations that are representative of the United
States population as a whole. This is similar to the situation for blood mercury concentrations. Limited
data from smaller studies are described below and summarized in Table 6-3.
U.S. Communities
Crispin-Smith et al. (1997) analyzed hair mercury concentrations in 1431 individuals living in the
United States. The communities in which these individuals resided were not identified. Mean values in
these studies were < 1 ug/g. Fish consumers had slightly higher blood mercury concentrations than did
nonfish consumers (0.52 vs. 0.48). The maximal value reported in this survey was 6.3 ug/g. Statistical
information on these data is not available currently.
New York Metropolitan Area, New Jersey, Alabama (Birmingham), and North Carolina
(Charlotte)
Creason et al. (1978a, 1978b, and 1978c) evaluated children and adults living in these cities in the
early 1970s. Mean values for all groups of children and adults were less than 1 ug/g. Maximum values
were in the range of 5 to 11.3 u,g/g of hair. Adult values were slightly higher than those of children.
California
Airey (1983) determined hair mercury concentrations among about 100 subjects living in Southern
California (LaJolla and San Diego). Mean values were in the range of 2 to 3 ug Hg/gram, with maximum
values in the range of 4.5 to 6.6 ug/g.. Harnly et al. (1997) determined hair mercury among Tribal and
nontribal group members living near Clear Lake, California. Mean values were typically less than 1 ug/g.,
with maximum values of 1.8 ug/g. among Tribal members and 2.3 pg/g among non-Tribal members.
Maryland
Airey (1983) found mean concentrations of about 1.5 to 2.3 ug/g in adults living in Maryland
(communities were not identified). Maximum concentrations were 4.5 ug/g..
State of Washington
Lazaret et al. (1991) identified hair mercury concentrations < 1 ug/g. and a maximum value of 1.5
ug/g. Earlier Airey (1983) reported mean values of 1.5 to 3.8 ug/g among small numbers of subjects. The
maximum value reported was 7. 9 ug/g.
Florida
CDC (1993) surveyed 330 subjects living in the Florida Everglades and determined that average
hair mercury concentrations were 1.3 ug/g.. The maximum value was 15.6 ug/g.
6-10
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Wisconsin
Knobeloch et al. (1995) reporting on two individuals with blood mercury concentrations of 38 and
>50 jig/g. found the individuals hair mercury concentrations were 11 and 12 ng/g.
Great Lakes Region
Gerstenberger et al. (1997) determined mean mercury concentrations were less than one |ig/g.
among 78 Ojibwa Tribal members. The maximum hair mercury concentration was 2.6 ug/g.
Alaska
Lazaret et al., (1991) reported hair mercury concentrations averaging 1.4 ng/g among 80 women of
childbearing age. The maximum hair mercury concentrations were 15.2 ng/g.
Table 6-3
Hair Mercury Concentrations (ug Hg/gram hair or ppm) from Residents
of Various Communities in the United States
Study
Creason et al.,
1978a
Creason et al.,
1978b
Creason et al.,
1978c
Community
New York
Metropolitan Area
Four communities in
New Jersey:
Ridgewood,
Fairlawn, Matawan
and Elizabeth
Birmingham,
Alabama, and
Charlotte, North
Carolina
Mean
Concentration
Children (n=280);
0.67 ppm
Adults (n=203);
0.77
Children (n=204),
0.77 ppm
Adults (n=l 17),
0.78 ppm
Children (n=322),
0.46 ppm
Adults (n- 11 7) 0.78
ppm
Maximum
Concentration
Children, 11.3 ppm
Adults, 14.0 ppm
Children, 4.4 ppm
Adults, 5.6 ppm
Children, 5.4 ppm;
Adults, 7.5 ppm
Additional
Information on
Study
Survey conducted
in 1971 and 1972
Survey conducted
in 1972 and 1973
Survey conducted
in 1972 and 1973
6-11
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Table 6-3 (continued)
Hair Mercury Concentrations (ug Kg/gram hair or ppm) from Residents
of Various Communities in the United States
Study
Airey, 1983
Airey, 1983
Airey, 1983
Community
U.S. data cited by
Airey, 1983.
Community not
identified.
U.S. data cited by
Airey, 1983
Community
identified: LaJolla-
San Diego
U.S. data cited by
Airey, 1983. Area
identified: Maryland
Mean
Concentration
1) Males (n=22),
2.7 ppm;
2). Females (n=l 6),
2.6 ppm;
3) Males and
Females (24
subjects), 2.1 ppm;
4) Males and
Females (3 1
subjects), 2.2 ppm;
5) Males and
Females 924
subjects) 2.9 ppm;
6) Males and
Females (79
subjects), 2.4 ppm.
1) 2.4 ppm (13
men);
2) 2.7 ppm (13
women);
3) 2.3 ppm (8
subjects including
men and women);
4) 2.9 ppm (17
subjects including
men and women);
5) 2.6 ppm (5
subjects including
men and women);
6) 2.8 ppm (30
subjects including
men and women).
1)1. 8 ppm (11
subjects, men and
women);
2) 1.5 ppm (11
subjects, men and
women);
3) 2.3 ppm (11
subjects, men and
women);
4) 1.9 ppm (33
subjects, men and
women).
Maximum
Concentration
1) 6.2 ppm
2) 5.5 ppm
3) 5.6 ppm
4) 6.6 ppm
5) 7.9 ppm
6) 7.9 ppm
1) 6.2 ppm
2) 5.5 ppm
3) 4.5 ppm
5) 6.2 ppm
6) 6.6 ppm
1) 3.8 ppm
2) 3.9 ppm
3) 4.5 ppm
4) 4.4 ppm
Additional
Information on
Study
»
6-12
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Table 6-3 (continued)
Hair Mercury Concentrations (ug Hg/gram hair or ppm) from Residents
of Various Communities in the United States
Study
Airey, 1983
Crispin-Smith et
al., 1997
Lasoraet al., 1991
Lasoraet al., 1991
Fleming et al.,
1995
Knobeloch et al.,
1995
Community
U.S. data cited by
Airey, 1983
Community
identified: Seattle.
U.S., Communities
and distribution not
identified
Nome, Alaska
Sequim, Washington
Florida Everglades
Wisconsin, urban
Mean
Concentration
1)3.3 ppm (9 men);
2. 2.2 ppm (3
women);
3) 2.6 ppm (5
subjects men and
women);
4) 1.5 ppm (3
subjects, men and
women);
5) 3.8 ppm (8
subjects, men and
women);
6) 3.0 ppm (16
subjects, men and
women).
0.48 ppm (1,431
individuals);
0.52 ppm (1009
individuals
reporting some
seafood
consumption)
1 .36 ppm
(80 women of
childbearing age)
0.70 ppm (7 women
of childbearing age)
1.3 ppm (330
subjects, men and
women)
2 adults (1 man, 1
woman); values 1 1
and 12 ppm
Maximum
Concentration
1) 5.6 ppm
2) 4.1 ppm
3) 5.6 ppm
4) 2.1 ppm
5) 7.9 ppm
6) 7.9 ppm
6.3 ppm
15.2 ppm
1 .5 ppm
15.6 ppm
Additional
Information on
Study
"
The 1009
individuals are a
subset of the 1431
subjects.
To be included in
the survey the
subjects had to have
consumed fish or
wildlife from the
Everglades.
6-13
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Table 6-3 (continued)
Hair Mercury Concentrations (ug Hg/gram hair or ppm) from Residents
of Various Communities in the United States
Study
Gerstenberger et
al., 1997
Harnlyetal., 1997
Community
Ojibwa Tribal
members from the
Great Lakes Region
Native Americans
living near Clear
Lake, California.
Mean
Concentration
47% > 0.28 ppm.
Among individuals
with values above
the level of
detection, the mean
was 0.83 ppm based
on 78 subjects
68 Tribal members.
Mean value: 0.64
ppm.
4 non-Tribal
members. Mean
value: 1.6 ppm
Maximum
Concentration
2.6 ppm
Maximum value for
Tribal members:
1.8 ppm
Maximum value for
non-Tribal
members: 2.3 ppm
Additional
Information on
Study
6.5.2.2 Summary of Data on Hair Mercury Concentrations
Available data indicate that mean mercury concentrations in the U.S. population are typically less
than 3 pg/g and often less than 1 ng/g, although, maximum concentrations of more than 15 jag/g are
reported. Hair mercury concentrations of greater than 10 ug/g have been associated with mercury
exposure from fish. The shape of the distribution of hair mercury concentrations in the United States is not
well documented. Comparison of data summarized by Airey (1983) on the association between frequency
of fish meals, mean and range of hair mercury concentrations reveals (see Table 6-4):
The arithmetic mean of hair mercury from the U.S. surveys is consistent with the lower
bound of the range associated with fish ingestion rates of less than once a month to as
frequent as once a week.
The maximum values identified in the surveys are consistent with fish consumption of
every week to every day.
Table 6-4
Association of Hair Mercury Concentrations (ug Hg/gram hair) with
Frequency of Fish Ingestion by Adult Men and Women
Living in 32 Locations within 13 Countries (Airey, 1983)
Frequency of Fish Meals
Once a Month or Less
Twice a Month
Every Week
Every Day
Arithmetic Mean
1.4
1.9
2.5
11.6
Range
0.1-6.2
0.2-9.2
0.2-16.2
3.6-24.0
6-14
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6.6 Conclusions
6.6.1 Blood Mercury Levels
Mercury in blood is a reflection of exposures in recent days and weeks to environmental mercury.
Typically blood mercury values are reported as total mercury, although chemically speciated mercury
analyses often are included in reports published in the 1990s. Organic mercury in blood generally reflects
methylmercury intake from fish and shellfish. At progressively higher dietary intakes of fish and shellfish,
ithe fraction of total blood mercury that is organic mercury increases becoming more than 95% at high
levels offish consumption.
Blood mercury concentrations (fig Hg/L) in healthy populations are less than 3 ug/L (5 ug/kg
packed cells and 0.5 ug/L serum) based on values published by the International Union for Pure and
Applied Chemistry (1996). The U.S. EPA RfD is associated with a whole blood mercury concentration of
4 to 5 ug/L. The "benchmark dose" for methylmercury used in setting the RfD is 44 ug/L based on
neurotoxic effects observed in Iraqi children exposed in utero.
There are no representative data on blood mercury for the U.S. population as a whole. In the
United States (in the peer-reviewed literature published in the 1990s), blood mercury concentrations in the
range of 50 to 95 ug/L have been reported and attributed to the consumption of fish and shellfish. Among
groups of anglers and Native American Tribal groups, mean blood mercury levels in the range of 10 to 20
ug/L have been reported. Blood mercury concentrations greater than 20 ug/L and attributable to
consumption of fish and shellfish have been identified among women of childbearing age in the United
States.
6.6.2 Hair Mercury Levels
Mercury is incorporated in hair as it grows. Typically the centimeter of hair nearest the scalp
reflects mercury exposure during the past month. The extent to which the predominant chemical species
in hair is a function of methylmercury exposure depends on environmental exposure patterns.
Methylmercury in the diet results in elevated hair mercury concentrations. Dietary sources documented to
produce elevated hair mercury concentrations include fish, shellfish, and flesh from marine mammals.
There are no representative data on hair mercury concentrations for the U.S. population as a
whole. Typical values in the United States are less than 1 ng/g. Maximum hair mercury concentrations of
15 ug/gram and higher have been reported in the United States. Hair mercury concentrations greater than
10 ug/gram have been reported for women of childbearing age living in the United States. U.S. EPA's
RfD is associated with a hair mercury concentration of approximately 1 ug/g. The "benchmark" dose is
associated with a hair mercury concentration of 11.1 ug/g and is based on neurotoxic effects observed in
Iraqi children exposed in utero to methylmercury.
6-15
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7. CONCLUSIONS
The results of the current exposure of the U.S. population from fish consumption indicate that
most of the population consumes fish and is exposed to methylmercury as a result. Approximately
85% of adults in the United States consumer fish and shellfish at least once a month with about
half of adults selecting fish and shellfish as part of their diets at least once a week (based on food
frequency data collected among more than 19,000 adult respondents in the NHANES HI
conducted between 1988 and 1994). This same survey identified 1-2% of adults who indicated
they consume fish and shellfish almost daily.
For the modeled fish ingestion scenarios, the local emission sources are predicted to account: for
the majority of the total mercury exposure for water bodies close to the sources. This is
particularly true for the hypothetical western site, where background and regional atmospheric
contributions to the total mercury concentration in the water column are predicted to be lower.
Consumption of fish is the dominant pathway of exposure to methylmercury for fish-consuming
humans. There is a great deal of variability among individuals in these populations with respect to
food sources and fish consumption rates. As a result, there is a great deal of variability in
exposure to methylmercury in these populations. The anthropogenic contribution to the total
amount of methylmercury in fish is, in part, the result of anthropogenic mercury releases from
industrial and combustion sources which increases mercury body burdens in fish. As a
consequence of human consumption of the affected fish, there is an incremental increase in
exposure to methylmercury. Terrestrial exposures were evaluated in the modeling analysts;
inorganic mercury species were predicted to be the dominant chemical species to which humans
are exposed.
In the nationally-based dietary surveys, the types of fish most frequently reported to be eaten by
consumers are tuna, shrimp, and Alaskan pollock. The importance of these species is
corroborated by U.S. National Marine Fisheries Service data on per capita consumption rates of
commercial fish species.
National surveys indicate that Asian/Pacific Islander-American and Black-American
subpopulations report more frequent consumption of fish and shellfish than other survey
participants.
Superimposed on this general pattern of fish and shellfish consumption is freshwater fish
consumption, which may pose a significant source of methylmercury exposure to consumers of
such fish. The magnitude of methylmercury exposure from freshwater fish varies with local
consumption rates and methylmercury concentrations in the fish. The modeling exercise indicated
that some of these methylmercury concentrations in freshwater fish may be elevated as a result of
mercury emissions from anthropogenic sources. Exposures may be elevated among some
members of this subpopulation; these may be evidenced by analyses of blood mercury showing
concentrations in excess of 10 micrograms per liter (ug/L) that have been reported among multiple
freshwater fish-consumer subpopulations. The mean value of blood mercury in an Arkansas study
was lOug/L. Because general populations data on the distribution of blood mercury
concentrations have not been gathered, it is not known how common blood mercury concentration
above lOpg/L are.
7-1
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An assessment of consumption offish and shellfish was based on data obtained from
contemporary nationally based dietary surveys conducted by the United States government: the
third National Health and Nutrition Examination Survey conducted between 1988 and 1994
(National Center for Health Statistics of the Centers for Disease Control) and the 1994 and 1995
Continuing Surveys of Food Intakes by Individuals (United States Department of Agriculture).
Data on mercury concentrations in fish and shellfish were obtained from national database
compiled by the National Marine Fisheries Service and the U.S. Environment Protection Agency.
The results of the assessment show that the predicted average exposure among make and female
fish consumers of reproductive age is 0.1 micrograms of methylmercury per kilogram of body
weight per day based on a single day's estimate. The comparable 90th percentile estimate is
approximately four times this level. Median "per user" fish/shellfish consumption values across
these nationally representative surveys were between 73 and 79 grams/day based on single-day
estimates. The comparable 90th percentile values ranged between 186 and 242 grams/day based
on single-day estimates.
The single-day estimates are used to project month-long fish/shellfish consumption when
combined with frequency of fish/shellfish consumption estimates obtained from adult participants
in NHANES HI. The single-day estimates of fish/shellfish consumption provide portion sizes to
estimated the impact of intermittent consumption of fish containing mercury at concentrations
considerably above that commonly encountered in the commercial market, e.g., approximately 0.5
ppm and higher. Fish with mercury concentrations averaging over 0.5 ppm include swordfish and
shark among marine fish and smallmouth bass, largemouth bass, channel catfish, walleye, and
northern pike among freshwater fish.
Exposure rates to methylmercury among fish-consuming children are predicted to be higher than
for fish-consuming adults on a body weight basis. The 50th percentile exposure rate among fish-
consuming children ages 3 through 6 years is approximately 0.3 micrograms per kilogram of body
weight per day based on single day estimates. Predicted exposures at the 90th percentile are
approximately three-times greater or 0.8 to one microgram of mercury per kilogram of body weight
on a single day. Estimated month long mercury exposures among 3 through 6 year-old children
are 0.03 at the 50th percentile and 0.17 at the 90th percentile using adult data to predict how often
children consume fish and shellfish. It is uncertain how well the adult data are predictive for
children because data for children are not available.
Exposures among specific subpopulations including anglers, Asian-Americans, and members of
some Native American Tribes indicate that their average exposures to methylmercury may be more
than two-times greater than those experience by the average population.
Predicted high-end exposures to methylmercury are caused by one or two factors or their
combination: 1) high consumption rates of methylmercury contaminated fish, water and/or 2)
consumption of types of fish which exhibit elevated methylmercury concentrations in their tissues.
Of these two factors the former appears to be more significant for overall population exposures.
Blood mercury concentrations and hair mercury levels are biomarkers used to indicate exposure to
mercury. Inorganic mercury exposures occur occupationally and for some individuals through
folk/hobby exposures to inorganic mercury. Dental restorations with silver-mercury amalgams can
also contribute to inorganic mercury exposures. Methylmercury exposure is almost exclusively
through consumption of fish, shellfish, and marine mammals. Occupational exposures to
methylmercury are rare.
7-2
-------
Data describing blood and/or hair mercury for a population representative of the United States do
not exist, however, some data are available. Blood mercury concentrations, attributable to
consumption of fish and shellfish, in excess of 30 ug/L have been reported in the United States.
Hair mercury concentrations in the United States are typically less than l|ag/g, however, hair
mercury concentration greater than lOu/g have been reported for women of childbearing age living
in the United States. U.S. EPA's RfD is associated with a blood mercury concentration of 4-5
ug/L and a hair mercury concentration of approximately lug/g. The "benchmark" dose is
associated with mercury concentrations of 44ug/L in blood and 11.1 ug/g in hair. The
"benchmark" dose for methylmercury is based on neurotoxic effects observed in Iraqi children
exposed in utero to methylmercury.
To improve the quantitative exposure assessment modeling component of the risk assessment for
mercury and mercury compounds, U.S. EPA would need more and better mercury emissions data
and measured data near sources of concern, as well as a better quantitative understanding of
mercury chemistry in the emission plume, the atmosphere, soils, water bodies, and biota:
To improve the exposure estimated based on surveys of fish consumption, more study is needed
among potentially high-end fish consumers, which examines specific biomarkers indicating
mercury exposure (e.g., blood mercury concentrations and hair mercury concentrations).
A pharmacokinetic-based understanding of mercury partitioning in children is needed. Additional
studies of fish intake and methylmercury exposure among children are needed.
7-3
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8. RESEARCH NEEDS
To improve the quantitative exposure assessment modeling component of the risk assessment for
mercury and mercury compounds, U.S. EPA would need more and better mercury emissions data
and measured data near sources of concern, as well as a better quantitative understanding mor
mercury chemistry I the emission plume, the atmosphere, soils, water bodies, and biota.
To improve the exposure estimated based on surveys of fish consumption, more study in needed
among potentially high-end fish consumers, which examines specific biomarkers indicating
mercury exposure (e.g., blood mercury concentrations and hair mercury concentrations).
A pharmacokinetic-based understanding of mercury partitioning in children is needed. Additional
studies of fish intake and methylmercury exposure among children are needed.
8-1
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Table 4-6
CSFII1994 Data Days 1 and 2
Gender
Aged 14 Years
or Younger
Aged 15
through 44
Aged 15 and
Older
Total for All
Age Groups
Number of Individuals with Dietary Recalls Day 1
Males
Females
Total
% consumption fish
932
942
1874
7.9
852
842
1694
10.9
869
859
1728
15.4
2653
2643
5296
11.3
Respondents Reporting Consumption of All Fish and Shellfish Day 1
Males
Females
Total
65
83
148
90
94
184
138
128
.266
293
305
598
Number of Individuals with Dietary Recalls Day 2*
Males
Females
Total
% consumption fish
993
941
1874
8.6
852
840
1692
10.2
868
859
1727
15.1
2653
2640
5293
11.3
Respondents Reporting Consumption of All Fish and Shellfish Day 2
Males
Females
Total
74
88
162
86
87
173
132
129
261
292
304
596
'"Methodology changes based on two 24-hour recalls, not necessarily sequential.
To assess whether or not there were seasonal differences in fish and shellfish consumption, the
year was divided into six two-month intervals. Fish intake data was analyzed by season. These values are
shown in Table 4-8.
4-9
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Table 4-7
CSFII1995 Data Days 1 and 2
Gender
Aged 14 Years or
Younger
Aged 15 through
44
Aged 15 and
Older
Total for All Age
Groups
Number of Individuals with Dietary Recalls Day 1
Males
Females
Total
% Consuming
Fish
863
808
1,671
7.5
649
635
1,284
11.7
1,067
1,041
2,108
15.4
2,579
2,484
5,063
11.9
Respondents Reporting Consumption of All Fish and Shellfish Day 1
Males
Females
Total
63
63
126
77
73
150
170
155
325
310
291
601
Number of Individuals with Dietary Recalls Day 2
Males
Females
Total
% Consuming
Fish
862
809
1,671
8.8
648
634
1,282
12.9
1,067
1,042
2,109
14.5
2,577
2,485
5,062
12.2
Respondents Reporting Consumption of All Fish and Shellfish Day 2
Males
Females
Total
81
67
148
82
84
166
168
138
306
331
289
620
Table 4-8
Fish Consumption (gms) by Season for Respondents Reporting Seafood Consumption
CFSII1994 Day 1
Statistics
Mean
Std. Dev*
Minimum
Maximum
Season
Jan/Feb
102
74
2
373
Mar/Apr
92
74
1
488
May/Jun
92
82
2
960
Jul/Aug
107
87
1
903
Sep/Oct
100
77
2
413
Nov/Dec
105
77
2
517
4-10
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Table 4-8 (continued)
Fish Consumption (grams) by Season for Respondents Reporting Seafood Consumption
CFS II1994 Day 1
Statistics
Season
Jan/Feb
Mar/Apr
May/Jun
JuI/Aug
Sep/Oct
Nov/Dec
Percentiles
5th
10th
25th
Median
75th
90th
95th
Observations
Sum of Weights (OOOs)
14
28
50
86
114
202
293
183
10,197
10
19
51
73
123
173
227
219
11,383
22
28
42
57
118
190
295
210
11,817
21
28
53
85
139
196
272
242
11,506
12
23
49
79
129
204
253
191
9,573
14
24
48
85
165
189
235
163
9,113
* The values in these cells are the weighted standard deviations of the individual observations. Estimates
of the standard errors of the means were not calculated.
4.1.1.7 NHANES HI General Description
The NHANES III, conducted between 1988 and 1994, used a multistage probability design that
involved selection of primary sampling units, segments (clusters of households) within these units,
households, eligible persons, and finally sample persons. Primary sampling units typically were composed
of a county or group of contiguous counties. Certain subgroups in the population that were of special
interest for nutritional assessment were oversampled: preschool children (six months through five years
old)1, persons 60 through 74 years old, and the poor (persons living in areas defined as poor by the United
States Bureau of the Census for the 1990 census). The U.S. Bureau of the Census selected the NHANES
III sample according to rigorous specifications from the National Center for Health Statistics so that the
probability of selection for each person in the sample could be determined.
The statistics presented in the report are population estimates. The findings for each person in the
sample were inflated by the reciprocal of selection probabilities, adjusted to account for persons who were
not examined, and stratified afterward according to race, sex and age, so that the final weighted population
estimates closely approximated the civilian noninstitutionalized population of the United States as
estimated independently by the U.S. Bureau of the Census at the midpoint of the survey, March 1, 1990.
Although children are oversampled in the survey design, not all assessmsents were carried out among
young children. For example, 24-hour dietary recall data were obtained for children, however, frequency offish
consumption information was not obtained.
4-11
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Although NHANES HI was conducted between 1988 and 1994, data on food consumption only
became available in 1996. The survey includes one 24-hour recall obtained by a trained interviewer. This
data base contains 29,973 dietary records including 3864 individuals who consumed fish and shellfish
(Table 4-9). Consumption of fish differed by age. Overall 12.9% of respondents included fish or shellfish
in their 24-hour dietary recall. As observed in CSFn 1994, the data among children aged 14 years and
younger was about half the percentages of fish consumption for ages 45 and older (Tables 4-10 and 4-11).
There were questions on frequency offish/shellfish consumption in the CSFn 1994 and CSFn 1995 data
bases; however, the specific information obtained excluded canned fish. Consequently, these data were
not used to estimate month-long fish consumption. The 24-hour recall data were analyzed for both
children and adults.
Table 4-9
AH Age Groups NHANES HI
Total
Fish Consumption
% Consumption Fish
Ages 14 and
Younger
12,048
1060
8.8
Ages 15
through 44
Years
10,041
1527
15.2
Ages 45 and
Older
7,884
1274
16.2
Total
29,973
3861
12.9
Table 4-10
NHANES III Adult Respondents
Gender
Ages 15 to 44
Years
Age 45 Years
and Older
Total Respondents
Males
Females
Total
4,620
5,421
10,041
3,783
4,101
7,884
Total for All Age
Groups
8,403
9,522
29,989
Respondents Reporting Fish Consumption
Males
Females
Total
664
883
1527
605
645
1274
1269
1528
2801
4-12
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Table 4-11
NHANES HI Child Respondents
Age Group
1-5 Years
6-11 Years
12-14 Years Female
12-14 Years Male
Total
Total
7595
3217
660
576
12,048
Fish Consumers
626
323
58
53
1060
% Reporting Fish
8.2
10.0
8.8
9.2
8.8
4.1.2 Frequency of Consumption of Fish Based on Surveys of Individuals
4.1.2.1 CSFD 1989-1991
In the USDA 1989 through 1991 Continuing Surveys of Food Intake by Individuals (CSFD 89-
91), food consumption data were obtained from nationally representative samples of individuals. These
surveys included women of child-bearing age 15 through 44 years of age. Data from the CSFn for the
period including 1989 and 1991 were used to calculate fish intake by the general population and women of
child-bearing age. This subpopulation included pregnant women, which are a subpopulation of interest in
the Mercury Study: Report to Congress, because of the potential developmental toxicity to the fetus
accompanying ingestion of methylmercury. Analysis of Vital and Health Statistics data from 1990
indicated that 9.5% of women in this age group can be predicted to be pregnant in a given year. The size
of this population has been estimated using the methodology described in the Addendum to this chapter,
entitled "Estimated National and Regional Populations of United States Women of Child-Bearing Age."
The data described in this section were obtained from nationally representative samples of
individuals and were weighted to reflect the U.S. population using the sampling weights provided by
USDA. The basic survey was designed to provide a multistage stratified area probability sample
representative of the 48 conterminous states. Weighting for the 1989, 1990 and 1991 data sets was done in
two stages. In the first phase a fundamental sampling weight (the inverse of the probability of selection)
was computed and the responding weight (the inverse of the probability of selection) was computed for
each responding household. This fundamental sampling weight was then adjusted to account for non-
response at the area segment level. The second phase of computations used the weights produced in the
first phase as the starting point of a reweighing process that used regression techniques to calibrate the
sample to match characteristics thought to be correlated with eating behavior.
The weights used in this analysis reflect CSFn individuals providing intakes for three days.
Weights for the 3-day individual intake sample were constructed separately for each of the three gender-
age groups: males ages 20 and over, females ages 20 and over and persons aged less than 20 years.
Characteristics used in weight construction included day of the week, month of the year, region,
urbanization, income as a percent of poverty, food stamp use, home ownership, household composition,
race, ethnicity and age of the individual. The individual's employment status for the previous week was
used for persons ages 20 and older, and the employment status of the female head of household was used
for individuals less than 20 years of age. The end result of this dual weighting process was to provide
consumption estimates which are representative of the U.S. population.
4-13
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Respondents were drawn from stratified area probability samples of noninstitutionalized U.S.
households. Survey respondents were surveyed across all four seasons of the year, and data were obtained
across all seven days of the week. The dietary assessment methodology consisted of assessment of three
consecutive days of food intake, measured through one 24-hour-recall and two 1-day food records. For
this analysis, the sample was limited to those individuals who provided records or recalls of three days of
dietary intake.
For purposes of interpretability, it should be noted that assessment of fish consumption patterns by
recall/record assessment methods will probably differ from assessments based on food frequency methods
(See Section 4.1.2.3, below). In order to be designated a consumer or "user" of fish for purposes of the
present analysis, an individual would need to have reported consumption of one or more fish/shellfish
products at some time during the three days when dietary intake was assessed. Since fish is not a
frequently consumed food for the majority of individuals, this dietary assessment method will likely
underestimate the extent of fish consumption, because some individuals who normally consume fish will
be missed if they did not consume fish during the three days of assessment. In contrast, such users would
be picked up by a food frequency questionnaire. The recall/record dietary assessment method does have
the advantage, however, of providing more precise estimates of the quantities of fish consumed that would
be obtained with a food frequency record.
The information that follows comes from the CSFE11989-1991 and was provided under contract to
U.S. EPA by Dr. Pamela Haines of the Department of Nutrition of the University of North Carolina School
of Public Health. Data are presented for following groups of individuals surveyed by USDA in the CSFII:
data for the total population, data grouped by gender, and for data grouped by age-gender categories for the
age groups 14 years or younger, 15 through 44 years, and 45 years and older (Table 4-5).
Fish consumption was defined to reflect consumption of approximately 250 individual "Fish only"
food codes and approximately 165 "Mixed dish-fish" food codes present in the 1994 version of the USDA
food composition tables. The USDA maintains a data base (called the "Recipe File") that describes all
food ingredients that are part of a particular food. Through consultation with Dr. Betty Perloff, an USDA
expert in the USDA recipe file, and Dr. Jacob Exler, an USDA expert in food composition, the USDA
recipe file was searched for food codes containing fish or shellfish. The recipe was then scanned to
determine fish codes that were present in the recipe reported as consumed by the survey respondent. The
percent of the recipe that was fish by weight was determined by dividing the weight of the fish/shellfish in
the dish by the total weight of the dish.
As with most dietary assessment studies, multiple days of intake were averaged to reflect usual
dietary intake better. Intakes reported over the three-day period were summed and then divided by three to
provide consumption estimates on a per person, per day basis.
Fish consumption was defined within the following categories.
1. Fish and Shellfish, all types reflected consumption of any fish food code.
2. Marine Finfish, included fish not further specified (e.g., tuna) and processed fish sticks, as
well as anchovy, cod, croaker, eel, flounder, haddock, hake, herring, mackerel, mullet,
ocean perch, pompano, porgy, ray, salmon, sardines, sea bass, skate, smelt, sturgeon,
whiting.
3. Marine Shellfish included abalone, clams, crab, crayfish, lobster, mussels, oysters,
scallops, shrimp and snails.
4. Tuna, contained only tuna.
5. Shark, Barracuda, and Swordfish contained just these three species of fish.
6. Freshwater Fish contained carp, catfish, perch, pike, trout and bass.
4-14
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The analysis was stratified to reflect "per capita" (Table 4-12), as well as "per user" (Table 4-13),
consumption patterns. A "consumer" of Fish and Shellfish, all types was one who consumed any of the
included fish only or mixed-fish dish foods. A Marine Finfish consumer was one who consumed any of
the species of fish included within the marine finfish category, and so on for each category. The percent of
the population or subpopulation consuming fish was listed for the entire population, as well as gender
specific values, and age-gender category specific values.
Table 4-12
Consumption of Fish and Shellfish (gins/day), and Self-Reported Body Weight (kg)
in Respondents of the 1989-1991 CSFH Survey.
"Per Capita" Data for All Survey Respondents
(Data are weighted to be representative of the U.S. population.)
Gender
Males
Females
Aged 14 Years or
Younger
Mean
9
8
SD J kgb.
20
18
26
24
Aged 15 through
44 Years
Mean
19
14
SD
35
28
kg..
73
63
Aged 45 Years or
Older
Mean
20
18
SD
36
30
Kg..
90
67
Total
Mean
17
14
SD
33
27
kg*.
68
58
Table 4-13
Consumption of Fish and Shellfish (gms/day), and
Self-Reported Body Weight (kg) in Respondents of the 1989-1991 CSFII Survey
(Data for "Users" Only. Data are weighted to be representative of the U.S. population.)
Gender
Males
Females
Aged 14 Years or
Younger
Mean
32
29
SD
27
24
kg*.
28
24
Aged 15 through
44 Years
Mean
54
41
SD
39
35
kgbw
80
63
Aged 45 Years or
Older
Mean
51
42
SD
42
34
Kfc.
83
68
Total
Mean
49
40
SD
39
33
kg*.
59
54
Consumption of fish-only and mixed-fish-dishes was summed across the three available days of
dietary intake data. This sum was then divided by three to create average per day fish consumption figures.
In the tables that describe fish intake, information is presented on sample size, percent of the population
who consumed any product within the specified fish category, the mean grams consumed per day and the
mean grams consumed per kilogram body weight (based on self-reported body weights), standard
deviation, minimum, maximum, and the population intake levels at the 5th, 25th, 50th (median), 75th, and
95th percentiles of the intake distribution for each age-gender category. The means and standard
deviations were determined using a SAS program. Survey sample weights were applied. Analysis with
SAS does not take design effects into account, so the estimates of variance may differ from those obtained
if SUDAAN or such packages had been used. It should be noted, however, that the point estimates of
consumption (grams per consumer per day, grams per consumer per kilogram of body weight) will be
exactly the same between the two statistical analysis packages. Thus, the point estimates reported are
accurate and appropriate for interpretation on a national level.
4-15
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Data were obtained for 11,706 individuals reporting 3-days of diet in the 1989-1991 CSFn survey.
Analyses were based on data weighted through statistical procedures (as described previously) to be
representative of the U.S. population. The total group of respondents reporting consumption of finfish
and/or shellfish during the 3-day period were grouped as a subpopulation who consumed fish, as can be
observed in Table 4-13. Fish and shellfish (total fish consumption) were reported to be eaten by 3614
persons (30.9%) of the 11,706 of the survey respondents (see Tables 4-12 and 4-13). The subpopulation
considered to be of greatest interest in this Mercury Study: Report to Congress were women of child-
bearing age (15 through 44 year-old females). Among this group of women ages 15 through 44 years, 864
women of the 2837 surveyed (30.5%) reported consuming fish (see Tables 4-12 and 4-13). Within this
group, 334 women reported consumption of finfish during the 3-day survey period.
Consumption of fish and shellfish varied by species of fish. Overall, marine finfish (not including
tuna, swordfish, barracuda, and shark) and tuna were consumed by more individuals and in greater
quantity than were shellfish. Tuna fish was the most frequently consumed fish product, and separate tables
are provided that identify quantity of tuna fish consumed. Two other categories of finfish were identified:
freshwater fish and a category comprised of swordfish, barracuda, and shark. Freshwater fish were of
interest because U.S. EPA's analysis of the fate and transport of ambient, anthropogenic mercury emissions
from sources of concern in this report indicates that fish may bioaccumulate emitted mercury. Swordfish,
barracuda, and shark were also identified as a separate category. These are predatory, highly migratory
species that spend much of their lives at the high end of marine food web. These fish are large and
accumulate higher concentrations of mercury than do lower trophic level, smaller fish.
4. ] .2.2 Estimated Frequency of Fish/shellfish Consumption Based on Food Frequency Questions
in CSFH 1994 and NHANES m
Both surveys included questions on frequency of consumption of fish and shellfish. The specific
wording of the questions are shown in the box. The wording of CSFn 1994 separated canned fish from
fish making it difficult to provide an overall estimate of fish consumption because no separate question
addressed frequency of consumption of canned fish. The CSFH survey also provided a separate question
on whether of not any of the fish the respondent ate was caught by the respondent or someone known to
the respondent. Among those respondents who ate non-canned fish during the past 12-month period
(84.1 % of respondents), 37.5% indicated that they had consumed fish caught by themselves or a person
known to them. Shellfish were reported to have been consumed by 62.2% of respondents during the past
12-month period.
4-16
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Fish Consumption Survey Questions
CFSI11994
During the past 12 months, that is, since last (NAME OF MONTH), (have you/has NAME) eaten any
(FOOD) in any form?
Yes No
Shellfish 1 2
Fish, other than shellfish or canned fish 1 2
IF YES: Was any of the fish you ate caught by you or
someone you know? 1 2
NHANES III
N2. MAIN DISHES, MEAT, FISH, CHICKEN, AND EGGS
Times Day
g. Shrimp, clams, oysters,
crabs, and lobster per
Week Month Never or
2oW 3oM 4QN or
h. Fish including fillets, fish sticks
fish sandwiches, and tuna fish per
laD
2oW
3oM 4DN
or
DK
9nDK
9oDK
In the CSFII 1994 survey, subjects who consumed fish other than shellfish or canned fish were to
select the answer "yes." Because canned fish (e.g., tuna, sardines) represent major food items, a portion of
the fish consumers would indicate they were nonconsumers if they ate canned fish only. Consequently,
using the results from the CSFII 1994 question would underestimate the frequency of consumption offish.
NHANES IE included two questions on fish and shellfish consumption as part of the household
interview portion of the survey. The specific format and wording are shown below. Questions N2g and
N2h addressed shrimp/shellfish and fish separately. Respondents were asked to indicate their frequency of
consumption: never, or how often daily, weekly, or monthly they consumed shrimp/shellfish (g) or fish (h).
Analyses of data from these questions provided the estimates of frequency of fish and shellfish
consumption shown in Table 4-14.
Table 4-14
Frequency of Fish/Shellfish Ingestion and Percent of Respondents*
(NHANES III, Food Frequency Questionnaire, Weighted Data)
Number of times
per month
0
1 or more
2 or more
4 or more
8 or more
12 or more
24 or more
30 or more
All Adults
12
88
79
58
23
13
3
1
Women Aged
15 _ 44 Years
14
86
78
56
25
12
3
2
Men Aged
15 44 Years
11
89
81
58
29
14
3
2
Women Aged 45
Years and Older
11
89
80
61
30
15
2
1
Men Aged 45
Years and Older
9
91
83
63
31
14
3
2
*Adult subjects only. Food frequency data were not collected for children ages 11 and younger.
4-17
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Frequency of fish and shellfish consumption data have also been calculated by ethnic/racial
grouping. The groups were: Non-Hispanic whites ("Whites"), Non-Hispanic blacks ("Blacks") and
persons designated as "Other" who included persons of Asian/Pacific Islander ethinicity, Native
Americans, Non-Mexican Hispanics (predominately persons from Puerto Rica and other Carribean
Islands), and additional groups not in the categories "Whites" or "Blacks". Food frequency data for these
groups is shown in Tables 4-15 and 4-16.
Table 4-15a
Frequency of Fish and Shellfish Consumption by Percent among
AH Adults, Both Genders, Weighted Data, NHANES HI*
(Estimated Frequency Per Month)
Frequency per Month
Zero
Once a Month or More
Once a Week or More
Twice a Week or More
Three-Times a Week or More
Approximately Daily (6 Times
Per Week)
White
11.8
88.2
57.1
25.9
11.6
1.9
Black
11.3
88.7
63.5
31.9
15.0
3.3
Other
15.1
84.9
60.3
31.2
22.9
8.9
* Adult subjects only. Food frequency data were not collected for children aged 11 years and younger.
Table 4-15b
Frequency of Fish and Shellfish Consumption by Race/Ethnicity,
Women Aged 15-44 Years, Weighted Data, NHANES III
(Estimated Frequency Per Month)
Frequency per Month
Zero
Once a Month or More
Once a Week or More
Twice a Week or More
Three-Times a Week or More
Approximately Daily (6 Times
Per Week)
White
13.2
86.8
54.5
22.0
9.5
1.7
Black
10.1
89.9
62.8
31.7
15.9
3.2
Other
19.1
80.9
59.3
35.6
22.7
9.2
4-18
-------
Table 4-16a
Distribution of the Frequency of Fish and Shellfish Consumption by Race/Ethnicity
AH Adults, Both Genders, Weighted Data, NHANES HI
Percentile
50th
75th
90th
95th
Whites
4
8
13
17
Blacks
4
8
13
19
Other
5
10
22
32
Table 4-16b
Distribution of the Frequency of Fish and Shellfish Consumption By Race/Ethnicity
Among Adult Women Aged 15-44, Weighted Data, NHANES III
Percentile
50th
75th
90th
95th
Whites
4
7
11
15
Blacks
4
8
14
20
Other
5
10
23
31
Overall 88% of all adults consume fish and shellfish at least once a month with 58% of adults
consuming fish at least once a week. Between 13% and 23% consume fish/shellfish two or three times per
week. An estimated 3% indicate they consume fish and shellfish six times a week with 1 % of all
respondents indicating they eat fish and shellfish daily. Comparatively small differences exist based on
age and gender of adults. Two percent of women of reproductive age and 2% of men in the age range 15
through 44 years indicate they consume fish/shellfish daily.
Among diverse subpopulations those designated as "Other" consume fish and shellfish more
frequently than do individuals in groups identified as "White" and "Black". In the "Other" category 5% of
individuals consume fish and shellfish daily (95th percentile value). Approximately 10% of the
subpopulation of "Whites" consume fish and shellfish three-times or more per week with approximately
23% of persons in the "Other" classification consuming fish and shellfish three-times a week or more.
4.1.2.3 Frequency of Consumption of Various Fish Species by Respondents in NHANES HI
Grouping offish and shellfish species by habitat (i.e., freshwater, estuarine, and marine) was done
based on an organization developed by US EPA's Office of Water. Table 4-17 shows which species were
grouped into these three habitat categories.
4-19
-------
Table 4-17
Classification of Fish Species by Habitat*
Marine
Estuarine
Freshwater
Abalone
Barracuda
Clams (92%)
Cod
Crab (54%)
Flatfish (71%)
Haddock
Halibut
Lobster
Mackerel
Mussels
Ocean Perch
Octopus
Pollock
Pompano
Porgy
Salmon (99%)
Sardine
Scallop (99%)
Sea Bass
Seafood (e.g., fish sauce)
Shark
Snapper
Swordfish
Sole
Squid
Tuna
Whitefish
Whiting
Anchovy
Clams (8%)
Crab (46%)
Croaker
Flatfish (29%)
Flounder
Herring
Mullet
Oyster
Perch
Scallop (1%)
Scup
Shrimp
Smelts
Sturgeon
Carp
Catfish
Pike
Salmon (1%)
Trout
Unprocessed fish (Food Codes 2815061 and 2815065) were not classified by habitat.
Mean consumption rates for only males and females who reported consuming fish/shellfish in the
NHANES HI data set are shown in Table 4-18. Consumption rates for species grouped as marine,
estuarine, and freshwater are shown in Table 4-19. Marine fish are the most frequently consumed followed
by estuarine and freshwater fish. However, when freshwater fish are consumed the portion size is larger
than for marine or estuarine fish. Males consumed larger portions of any of the fish groups than did female
subjects.
4-20
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Table 4-18
Weighted Estimates of Fish and Shellfish Consumed (gins) for Females and Males Aged 15 - 44
Years Reported in NHANES III (Per User)
Statistic
Mean
Standard Deviation
Minimum
Maximum
Percentiles
5th
10th
25th
Median
75th
90th
95th
Observations
Sum of Weights (OOOs)
Females
103
116
1
117
12
20
37
73
131
228
288
883
1,162
Males
146
149
1
1097
14
28
51
97
185
345
435
645
9,223
Table 4-19
Weighted Estimates for Fish and Shellfish Consumed (gms) by Female and Male Respondents Aged
15 - 44 Years Reported in the NHANES III Survey by Habitat of Species Consumed
Statistic
Mean
Std. Dev
Minimum
Maximum
Marine Fish
Females
86
86
0
957
Males
113
122
0
1004
Estuarine Fish
Females
69
64
0
517
Males
122
131
0
981
Freshwater Fish
Females
158
138
7
740
Males
274
268
14
1097
Percentiles
5th
10th
25th
Median
75th
8
14
37
55
109
1
12
44
84
153
8
9
22
47
101
5
8
29
64
175
13
26
50
127
235
42
42
123
185
313
4-21
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Table 4-19 (continued)
Weighted Estimates for Fish and Shellfish Consumed (gins) by Female and Male Respondents Aged
15 - 44 Years Reported in the NHANES HI Survey by Habitat of Species Consumed
Statistic
90th
95th
Observations
Sum of Weights (OOOs)
Marine Fish
Females
209
247
519
6,457
Males
204
351
387
5,999
Estuarine Fish
Females
168
202
221
2,653
Males
355
357
198
2,477
Freshwater Fish
Females
330
330
82
516
Males
617
929
60
588
4.1.3 Subpopulations with Potentially Higher Consumption Rates
The purpose of this section is to document fish consumption rates among U.S. subpopulations
thought to have higher rates of fish consumption. These subpopulations include residents of the States of
Alaska and Hawaii, Native American Tribes, Asian/Pacific Island ethnic groups, anglers, and children;
these groups were selected for analysis because of potentially elevated fish consumption rates rather than
because they were thought to have a high innate sensitivity to methylmercury. The presented estimates are
the results of fish consumption surveys conducted on the specific populations. The surveys use several
different techniques and illustrate a broad range of consumption rates among these subpopulations. In
several studies the fish consumption rates of the subpopulations corroborate the high-end (90th percentile
and above) fish consumption estimates of the the nationwide food consumption surveys.
Many of the surveys of fish consumption conducted on high-end fish consumers also included
analyses for mercury in hair and blood of the people who were subjects. These data on biological
monitoring provide an additional bases to estimate mercury exposure.
4.1.3.1 Subpopulations Included in Nationally Representative Food Consumption Surveys
Contemporary food consumption surveys designed to be representative of the U.S. population as a
whole included identifiers for ethnically diverse subpopulations. Publicly available data from the
NHANES III combined three subpopulations of interest with regard to level of fish consumption:
Asian/Pacific origin, Native American origin, and others. By contrast, the CSFn 1994 and CSFII1995
surveys provided separate estimates for identified ethnic subpopulations: white, black, Asian and Pacific
Islander, Native American and Alaskan Native, and other (see Figure 4-1).
The 50th, 90th and 95th percentiles for all survey participants in CSFH 1994 and CSFII 1995 for
"Day 1" and "Day 2" recall data are shown in Table 4-20. The number of 24-hour recall food consumption
reports for each group is noted in the table food note. Data are presented for both "per capita" and "per
user." The subpopulation self-designated as "white" has the smallest intake of fish/shellfish and mercury
at the 50th percentile. "Blacks" have higher levels of intake and Asian and Pacific Islanders have the
highest intake offish/shellfish. Similar patterns are observed at the 90th and 95th percentile.
If the data are calculated for only those persons who reported consuming fish and shellfish, a
somewhat different pattern emerges. A median intake offish/shellfish is the lowest among Asian and
Pacific Islanders, intermediate among "whites" and highest among "blacks." The number of observations
among Native Americans and Alaska Natives are too small to produce reliable estimates.
4-22
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Figure 4-1
Distribution of Fish Consumption Rates of Various Populations
^ t | Wolfe A Walker'87 Highest Response Group Mean in AK j
390-
2SO-
CRITFC '94 99th %ile Adult
LEGEND - POPULATIONS
GENERAL U.S. POPULATION SUBSISTENCE FISHERS
NPD 73/74 jm
CSFII
RECREATIONAL ANGLERS
PUFFER ^
FIORE A
CONNELY W
WOLFE & WALKER
NATIVE AMERICANS
CRITFC m
TOY, TULALIP ^
NOBMAN
EPA '92 Wl TRIBES
A
-(Putter '89 90th %ile
CRITFC '94 95th %ile
[ Toy '95 Tulalip Tribe 90th %ile \
NPD 73/74 Adult 99th %ile
Nobmann '92 AK Tribes Mean |
Fiore '89 95th %ile
Wl Anglers
Toy '95 Tulalip Tribe Median
Putter '81 Median~]+
EPA'92 Wl Tribes | (
Fiore '89 75th %ile Wl Anglers
NPD 73^4 Adult 90th %ile
iore '89 Wl Anglersl^^ [Connoly '90 NY Anglers MeanJ+
\ CSFII Age 15-44 Mean ?
NPD 7374 Adult 50th %ile
4-23
-------
Table 4-20
Consumption of Fish and Shellfish (gins/day) among Ethnically Diverse Groups
(Source: CSFII1994 and CSFII1995)
Ethnic Group
White
50th Percentile
90th Percentile
95th Percentile
Black
50th Percentile
90th Percentile
95th Percentile
Asian and Pacific Islander
50th Percentile
90th Percentile
95th Percentile
Native American and Alaska Native
50th Percentile
90th Percentile
95th Percentile
Other
50th Percentile
90th Percentile
95th Percentile
Fish Consumption (grants/day)
Per Capita1
Zero
24
80
Zero
48
104
Zero
80
127
Zero
Zero
56
Zero
Zero
62
Per User1
72
192
243
82
228
302
62
189
292
Estimate not made because
of small numbers of
respondents.
83
294
327
'Total number of 24-hour food consumption recall reports: White (16,241); Black (2,580); Asian and
Pacific Islander (532); Native American and Alaska Native (166): and Other (1,195).
2 Number of 24-hour food consumption recall reports: White (1,821); Black (329); Asian and Pacific
Islander (155); Native American and Alaska Native (12); and Other (98).
4.1.3.2 Specialized Surveys
During the past decade, data describing the quantities of fish consumed by angler, economically
subsistent, and North American Tribal groups have been published (Tables 4-23 and 4-30).
Subpopulations of particular concern because of exposure patterns are Native Americans, sport anglers, the
urban poor, and children. Data on fish consumption for these groups indicate that exposures for these
subgroups exceed those of the general population of adults. If North American data, including those from
Canada, are considered, mercury exposures from the marine food web (especially if marine mammals are
consumed) exceed limits such as the Tolerable Daily Intake established by Health Canada (Chan, 1997)
and the Acceptable Daily Intake established by the U.S. Food and Drug Administration.
The data cited below on specific Subpopulations are not utilized in this Report as the basis of a
site-specific assessment. In a site-specific assessment the fish consumption rates among a surveyed
4-24
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population would be combined with specific measurements of methylmercury concentrations in the local
fish actually consumed to estimate the human contact rate. Ideally, some follow-up analysis such as
concentrations of mercury in human blood or hair would ensue.
Analytic and survey methods to estimate the fish consumption rates of the respondents are
described for each population. This chapter does not constitute an exhaustive review of the methods
employed. An attempt was made to characterize the population surveyed. Additionally, to characterize the
entire range of fish consumption rates in the surveyed populations, the consumption rates of both average
and high-end consumers as well as other specific angler subpopulations (e.g., fish consumption by angler
race or age) are presented.
The sources of consumed fish are also identified in the summaries. Fish consumed by humans can
be derived from many sources; these include self-caught, gift, as well as grocery and restaurant purchases.
Some studies describe only the consumption rates for self-caught fish or freshwater fish, others estimate
total fish consumption, and some delineate each source of fish. Humans also consume fish from many
different types of water bodies. When described by the reporting authors, these are also identified.
Assumptions concerning fish consumption made by the study authors are also identified. Humans
generally do not eat the entire fish; however, the species and body parts of fish which are consumed may
be highly variable among angler populations (for example, see Toy et al. 1995). Anglers do not eat their
entire catch, and, some species of fish are typically not eaten by specific angling subpopulations. For
example, Ebert et al. (1993) noted that some types and parts of harvested fish are used as bait, fed to pets
or simply discarded. Study authors account for the differences between catch weight and number in a
variety of different ways. Typically, a consumption factor was applied. These assumptions impact the
author's consumption rate estimates.
Data from angler and indigenous populations are useful in that they corroborate the ranges
identified in the 3-day fish consumption data. The data are not utilized in this Report as the basis of a site-
specific assessment. In a site-specific assessment the fish consumption rates among a surveyed population
would be combined with specific measurements of methylmercury concentrations in the local fish actually
consumed to estimate the human contact rate. Ideally, some follow-up analysis such as concentrations in
human blood or hair would ensue.
4.1.3.3 U.S. Subsistent Populations
Large urban populations include individuals who obtain some of their food by catching and eating
fish from local urban waters. For example, Waller et al. (1996) identified populations living along the lake
shore of Chicago who have ready access to fishing waters of Lake Michigan along the break waters, the
harbors, and in the park lagoons adjacent to Lake Michigan (Table 4-21). Similar situations occur for
many water bodies in urban areas throughout the United States.
4-25
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Table 4-21
Fish Consumption of an Urban "Subsistent" Group
Study
Description of
Group
Fish Consumption Pattern
Notes
Waller et al.
1996
484 pregnant African-
American, urban poor
women
45 of 444 ate no fish; 46 of 444
consumed sport-caught fish; 34
of the women who consumed
sport-caught fish also consumed
store-bought fish.
Types of fish eaten most frequently
in descending order: catfish, perch,
buffalo, silver bass, and whiting.
Others included: bull heads,
sunfish, bluegills, and crappie.
Most catfish consumed was store-
bought. Generally fisheaters did
not consume only one type offish.
Most of the individuals eating
sport-caught fish also ate wild fowl
and other game (duck, raccoon,
opossum, squirrel, turkey, goose,
and other fowl.
Another group of urban consumers who subsist on fish are persons who are not limited in income,
but individuals who choose to consume a large proportion of their dietary protein from fish because of taste
preference or pursuit of health benefits attributed to fish. For an undetermined number of these
individuals, a particular species of fish may be preferred (e.g., swordfish, sea bass, etc.) and consumed
extensively. Depending on the mercury concentration of the preferred fish, the result of consuming diets
high in fish from one source can be substantially increased exposure to mercury. For example, Knobeloch
et al. (1996) provide cases reports of a family whose blood mercury concentrations increased about ten-
fold following long-term consumption of a particular commercial source of imported fish (Table 4-22).
Likewise, investigation by state authorities in Maine of elevated blood mercury concentrations thought to
result from occupational exposures to mercury, in fact, resulted from frequent consumption of fish (Dr.
Allison Hawkes, 1997). After following physician's advise to reduce fish consumption the blood mercury
levels decreased.
Table 4-22
High Fish Consumption among Urban Subjects: Case Report
Study
Description of
Group
Fish Consumption Pattern
Notes
Knobeloch et
al., 1995
Family consuming
commercially available
fish.
Wisconsin family consumed two
meals/week of seabass imported
from Chile and obtained
commercially which had a mercury
concentration between 0.5 and 0.7
Mg/g. Other fish having low mercury
concentrations (<0.05 ug/g) were
also consumed. The father
consumed an average of 113 g of
fish/day, the mother and son
consumed approximately 75 and 37
grams of fish/day, respectively.
Calculated mercury intakes ranged
from 9 ng/day (young child) to 52
ug/day for the father in the
household.
Family members had blood mercury
levels elevated to 37 and 58 ug/L
and hair mercury values of 10 and 12
pg/g. Cessation of fish consumption
for 200 days reduced blood mercury
levels to 3 and 5 \ig/L.
4-26
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4.1.3.4 U.S. Immigrant Populations
Subpopulations of recent immigrants to the United States retain food patterns characteristic of their
cultures with adaptations based on the available food supply. In the 1980s and 1990s, the proportion of the
U.S. population whose ancestry was Southeast Asian or Caribbean origin increased. The people of rural
Cambodia, Laos, and Vietnam supplemented their agricultural resources by hunting and fishing (Shubat et
al., 1996) and many continue to do so in the United States. Puffer (1981) found that Oriental/Samoan
recreational anglers had fish consumption rates twice the mean value for all anglers in the survey.
Specialized fish advisories for chemical contaminants and outreach programs for Southeast Asian
communities have been developed (Shubat et al., 1996). Increased consumption of purchased frozen fish,
as well as self-caught fish, among Southeast Asians has been reported (Shatenstein et al., 1997). Overall,
these subpopulations have higher fish consumption than does the general U.S. population.
4.1.3.5 U.S. Angling Population Size Estimate and Behaviors
Many citizens catch and consume fish from U.S. waters. The U.S. Fish and Wildlife Service (U.S.
FWS, 1988) reported that in 1985, 26% of the U.S. population fished; over 46 million people in the U.S.
spent time fishing during 1985. Within the U.S. population fishing rates ranged from a low of 17% for the
population in the Middle Atlantic states up to 36% in the West North Central States. These angling
subpopulations included both licensed and non-licensed fishers, hook and line anglers as well as those who
utilized special angling techniques (e.g., bow and arrows, spears or ice-fishing).
U.S. FWS (1988) also noted the harvest and consumption offish from water bodies where fishing
is prohibited. This disregard or ignorance offish advisories is corroborated in other U.S. angler surveys.
For example, Fiore et al. (1989) noted that 72% of the respondents in a Wisconsin angler survey were
familiar with the State of Wisconsin Fish Consumption Health Advisory, and 57% of the respondents
reported changing their fishing or fish consumption habits based on the advisory. West et al. (1989) noted
that 87.3% of respondents were "aware or generally aware" of Michigan State's fish consumption
advisories. Finally, Connelly et al. (1990) reported that 82% of respondents knew about the New York
State fish health advisories. They also noted a specific example in which angler consumption exceeded an
advisory. The State of New York State recommends the consumption of no more than 12 fish meals/year
of contaminated Lake Ontario fish species; yet, 15% of the anglers, who fished this lake, reported eating
more than 12 fish meals of the contaminated species from the lake in that year.
The extent of the angling population can also be judged from a question included in the USDA's
CSFII for the years 1994 and 1995. In response to a question of whether or not they had eaten fish within
the past 12 months, 84% of individuals indicated they had. Of those who had eaten fish, 38% indicated
that the fish they had eaten was caught by themselves or someone known to the respondent.
4.1.3.6 U.S. Angler Surveys
Summary of Angler Surveys
The results of the fish consumption surveys are compiled in Table 4-23. These results illustrate
the range of fish consumption rates identified in angler consumption surveys. There is a broad range of
fish consumption rates reported for angling populations. The range extends from 2 g/day to greater than
200 g/day. The variability is the result of differences in the study designs and purposes as well as
differences in the populations surveyed.
4-27
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Table 4-23
Compilation of the Angler Consumption Studies
Source
Soldat, 1970
Puffer, 1981;
as cited in U.S.
EPA, 1990
Pierce et al.,
1981; as cited in
EPA, 1990
Fioreetal., 1989
Westetal. 1989
Westet al.. 1993
Turcotte, 1983
Hovinga et al.,
1992 and 1993
Ebertetal., 1993
Population
Columbia
River
Anglers
Los Angeles
area coastal
anglers
Commence-
ment Bay in
Tacoma, WA
Licensed WI
Anglers
Licensed MI
Anglers
Licensed MI
Anglers
GA anglers
Caucasians
living along
Lake
Michigan
ME anglers
licensed to
fish inland
waters
Percentile
Mean
Median
90th Percentile
Ethnic Subpopulation
Medians
African-American
Caucasian
Mexican-American
Oriental/Samoan
50th Percentile
90th Percentile
Maximum Reported
Mean
75th Percentile
95th Percentile
Mean
75th Percentile
95th Percentile
Mean
Mean for Minorities
Maximum Reported
Mean
Child
Teenager
Average Angler
Maximum Angler
Maximum Reported
Mean
50th Percentile
75th Percentile
90th Percentile
95th Percentile
Daily Fish
Consumption
g/day
2
37
225
24
46
33
71
23
54
381
12
16
37
26
34
63
19
22
>200
15
43
10
23
31
58
132
6
2
6
13
26
Notes
Estimate of average finfish
consumption from river.
Estimates for anglers and
family members who consume
their catch. Consumption rate
includes ingestion of both
finfish and shellfish.
Finfish only
Fish-Eaters, Daily Sportfish
Intake
Fish-Eaters, Total Fish Intake
Daily Sportfish Intake
Daily sportfish intake
Estimates of Freshwater Fish
Intake from the Savannah River
Re-examination of Previously
Identified High-End Fish
Consuming Population
Sportfish Intake
4-28
-------
Table 4-23 (continued)
Compilation of the Angler Consumption Studies
Source
Courval et al.,
1996
Meredith and
Malvestuto, 1996
Population
Data on
1,950
question-
naires from
Michigan
anglers aged
18-34 years.
29 locations
in Alabama.
Seasonal
estimates of
freshwater
fish
consumption
Percentile
Daily Fish
Consumption
g/day
46% of
respondents
reported eating
sport-caught fish
1-12 times: 20%
reported eating
no sport-caught
fish; 20%
consumed 1 3 to
24 meals.
Approximately
1 0% consumed
25 to more than
49 meals/month.
Compared
harvest method
and serving-size
methods of
estimating
consumption.
Harvest method
yielded estimates
of 43 grams/day
fish consumed
from all sites in
Alabama
(number = 563).
Serving-size
method
estimates 46
grams/day from
all sites in
Alabama
(number = 1311)
Consumption
lowest in the
Spring
Notes
Approximately 30% of female
respondents consumed no
sport-caught fish - about double
that of male respondents. In the
1 to 12 meal/month range males
and females about equally
represented. More than 13
meals/month exposure catego»y
had a higher proportion of
males.
Survey to determine
consumption rates of anglers
yielded comparable estimates of
grams/day consumed. However,
serving size method yielded
four-times as many consumers.
4-29
-------
Table 4-23 (continued)
Compilation of the Angler Consumption Studies
Source
Shubat et al.,
1996
Sekerke et al.,
1994
Population
30 Hmong
anglers
(residents of
St. Paul and
Minneapolis)
fishing St.
Croix or
Mississippi
Rivers. Ages
17-88.
FL residents
receiving
foodstamps
Percentile
Male Mean
Female Mean
Daily Fish
Consumption
g/day
Respondents ate
an average of
3.3±3.0 fish
meals per month
(range 0.5 to
12). Median 2
meals per month
and 8.8 meals at
90th percentile.
60
40
Notes
Consumption of caught fish
only. No information about
size of meals. Species most
frequently caught: crappie,
white bass and walleye, other
bass (largemouth and
smallmouth), northern pike,
trout, bluegill and catfish.
Total Home Rsh Consumption
Anglers of the Columbia River, Washington
Soldat (1970) measured fishing activity along the Columbia River during the daylight hours of one
calendar year (1967-68). The average angler in the sampled population made 4.7 fishing trips per year and
caught an average of 1 fish per trip. Assuming 200 g of fish consumed per meal, Soldat estimated an
average of 0.7 fish meals were harvested per trip; this results in an average of 3.3 Columbia River fish
meals/year. The product of 3.3 meals/year and 200 g/meal is 660 g/year; an estimate of 1.8 g/day results.
While not reporting the high-end harvesting or consumption rates, Soldat reported that approximately 15%
of the 1400 anglers interviewed caught 90% of the fish.
Los Angeles, California Anglers
The results of studies from Puffer (1981) and Pierce et al. (1981) are described in U.S. EPA
(1989). Puffer (1981) conducted 1,059 interviews with anglers in the coastal Los Angeks area for an
entire year. Consumption rates were estimated for anglers who ate their catch. These estimates were based
on angling frequency and the assumption of equal fish consumption among all fish-eating family members.
The median consumption rate for fish and shellfish was 37 g/day. The 90th percentile was 224.8 g/day.
Table 4-24 notes the higher consumption rate estimates among Orientals and Samoans.
4-30
-------
Table 4-24
Median Recreationally Caught Fish Consumption Rate Estimates
by Ethnic Group (Puffer, 1981)
Ethnic Group
African -American
Caucasian
Mexican-American
Oriental/Samoan
Total
Median Consumption Rate
(g/day)
24
46
33
71
37
Anglers of the Commencement Bay Area in Tacoma, Washington
Pierce et al. (1981), as reported in the U.S. EPA 1990 Exposure Factors Handbook, conducted a
total of 509 interviews in the summer and fall around Commencement Bay in Tacoma, Washington. They
assumed that 49% of the live fish weight was edible and that 98% of the total catch was eaten. The
estimated 50th percentile consumption rate was 23 g/day and the estimated 90th percentile consumption
rate 54 g/day. The maximum estimated consumption rate was 381 g/day based on daily angling.
Anglers of the Savannah River in Georgia
Turcotte (1983) estimated fish consumption from the Savannah River based on total harvest,
population studies and a Georgia fishery survey (Table 4-25). The angler survey data, which included the
number of fishing trips per year as well as the number and weights of fish harvested per trip, were used to
estimate the average consumption rate in the angler population. Several techniques including the use of
the angler survey data were used to estimate the maximum fish consumption in the angler population.
Estimates of average fish consumption for children and teens was also provided.
Table 4-25
Freshwater Fish Consumption Estimates of Turcotte (1983)
Georgia
Subpopulation
Child
Teen-ager
Average Angler
Maximum Angler
Estimated Freshwater Fish
Consumption Rate (g/day)
10
23
31
58
4-31
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Alabama Anglers
Meredith and Malestuto (1996) studied anglers in 29 locations in Alabama to estimate freshwater
fish consumption (Table 4-23). The purpose of their study had been to compare two methods of estimating
fish consumption: The harvest or krill survey compared with the serving-size method of estimating fish
consumption. These two techniques yielded comparable estimates of mean fish intake (43 and 46
gms/person/day, respectively). The serving size method identified 1311 consumers while the harvest
method identified only 563 consumers.
Wisconsin Anglers
Fiore et al. (1989) surveyed the fishing and fish consumption habits of 801 licensed Wisconsin
anglers. The respondents were divided into 2 groups: fish eaters and non-eaters. The fish eaters group
was further subdivided into four groups: those who consumed 0-1.8 kg fish/yr, 1.9-4.5 kg fish/yr, 4.6-
10.9 kg fish/yr and 10.9 < kg fish/yr. Using an assumption of 8 oz. (227 grams) fish consumed/meal, the
authors estimated that the mean number of sport fish meals/year for all respondents (including non-eaters)
was 18. The mean number of other fish meals/year including non-eaters was 24. The total number of fish
meals/year was 41 for fish eaters and non-eaters combined and 42 for fish eaters only. Recreational
anglers were found to consume both commercial fish as well as sport fish. The estimated daily
consumption rates of the eaters-only are presented in Table 4-26.
Table 4-26
Daily Intake of Sportfish and Total Fish for the Fish-consuming Portion
of the Population Studied by Fiore et al. (1989)
Percentile
Mean
75th
95th
Daily Sport-Fish Intake
1 2 g/day
1 6 g/day
37 g/day
Daily Total Fish Intake
26 g/day
34 g/day
63 g/day
Michigan Anglers
West et al. (1989) used a mail survey to conduct a 7-day fish consumption recall study for licensed
Michigan anglers. The respondents numbered 1104, and the response rate was 47.3%. The mean fish
consumption rate for anglers and other fish-eating members of their households was 18.3 g/day, and the
standard deviation was 26.8 g. Because the study was conducted from January through June, an off-season
for some forms of angling in Michigan, higher rates of fish consumption would be expected during the
summer and fall months. A full-year's mean fish consumption rate of 19.2 g/day was estimated from
seasonal data. The mean fish consumption rate for minorities was estimated to be 21.7 g/day. The highest
consumption rates reported were over 200 g/day; this occurred in 0.1% of the population surveyed.
Overall, fish consumption rates increased with angler age and lower education levels. Lower income and
education level groups were found to be the only group which consumed bottom-feeders.
New York State Anglers
Connelly et al. (1990) reported the results of a statewide survey of New York anglers. The 10,314
respondents (62.4% response rate) reported a mean of 20.5 days spent fishing/year. Of the respondents,
4-32
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84% fished the inland waters of New York State, and 42% reported fishing in the Great Lakes. An overall
mean of 45.2 fish meals per year was determined for New York anglers. The authors assumed an average
meal size of 8 oz. (227 g) of fish and estimated a yearly consumption rate of 10.1 kg fish (27.7 g fish/day).
Unlike the Michigan angler study (West et al., 1989), the overall mean number offish meals consumed
increased with education level of the angler. Fish consumption also increased with increasing income;
respondents earning more than $50,000/year consumed a mean of 54.3 meals per year, and those with
some post-graduate education consumed a mean of 56.2 meals per year. The highest reported regional
mean consumption rates (58.8 meals/year) occurred in the Suffolk and Nassau Counties of New York
State.
Anglers of Lake Michigan
As part of a larger effort, Hovinga et al. (1992 and 1993) re-examined 115 eaters of Great Lakes
fish and 127 controls, who consumed smaller quantities of fish, originally identified in a 1982 effort. Both
more recent (1989) as well as 1982 consumption rates of Great Lakes sportfish were estimated. All of the
participants in the study were Caucasian and resided in 11 communities along Lake Michigan. The
population was divided into eaters (defined as individuals consuming 10.9 kg (30 g/day) or greater) and
controls (defined as individuals consuming no more than 2.72 kg/yr). The consumption rates for the
groups are reported in Table 4-27.
Table 4-27
Fish Consumption Rate Data for Groups Identified in
Hovinga et al. (1992) as Eaters and Controls
Groups
Eaters
Controls
1982
Meals/Year
Mean (Range)
54(24-132)
-
1982 Consumption
Rates (kg/yr)
Mean (Range)
18(11-53)
-
1989
Meals/Year
Mean (Range)
38(0-108)
4.1 (0-52)
1989 Consumption
Rates (kg/yr)
Mean (Range)
10(0-48)
0.73 (0-8.8)
Anglers of Inland Waters in the State of Maine
Ebert et al. (1993) examined freshwater fish consumption rates of 1,612 anglers licensed to fish
the inland (fresh) waters of Maine. They only analyzed fish caught and eaten by the anglers. Anglers were
asked to recall the number, species and average length of fish eaten in the previous year; the actual fish
consumption rates were estimated based on an estimate of edible portion of the fish. The 78% of
respondents who fished in the previous year and 7% who did not fish but did consume freshwater fish were
combined for the analysis. Anglers who practiced ice-fishing as well as fish caught in both standing and
flowing waters were included. Twenty-three percent of the anglers consumed no freshwater fish. If the
authors assumed that the fish were shared evenly among all fish consumers in the angler's family, a mean
consumption rate of 3.7 g/day was estimated for each consumer. Table 4-28 provides the fish consumption
rates for Maine anglers.
4-33
-------
Table 4-28
Fish Consumption Rates for Maine Anglers
Percentile
Mean
50th (median)
75th
90th
95th
All Anglers
5.0
1.1
4.2
11
21
Fish-consuming
Anglers
6.4
2.0
5.8
13
26
Florida Anglers Who Receive Food Stamps
As part of a larger effort the Florida Department of Environmental Regulation attempted to
identify fish consumption rates of anglers who were thought to consume higher rates offish. Face-to-face
interviews were conducted at five Florida food stamp distribution centers. The selected food stamp
distribution centers were located in counties either thought to have a high likelihood of subsistence anglers
or where pollutant concentrations in fish were known. Interviews with twenty-five household's primary
seafood preparer were conducted at each center per quarter for an entire year. A total of 500 interviews
was collected. The interviewed were asked to recall fish consumption within the last 7 days. Specifically,
the respondents were asked to recall the species, sources and quantities of fish consumed. Note that the
respondents were only asked to recall fish meals prepared at home (actual consumption rates may have
been higher if the respondents consumed seafood elsewhere) and that the sources of fish were from both
salt and freshwater. The results of the survey conducted by Sekerke et al. (1994) are in Table 4-29.
Table 4-29
Fish Consumption Rates of Florida Anglers Who Receive Food Stamps
1 Respondent
Adult Males
Adult Females
No.
366
596
Average Finfish
Consumption
60 g/day
40j£/day
Average Shellfish
Consumption
50 g/day
30 g/day
4.1.3.7 Indigenous Populations of the United States
The tribes and ethnic groups who comprise the indigenous populations of the United States show
wide variability in fish consumption patterns. Although some tribes, such as the Navajo, consume minimal
amounts of fish as part of their traditional culture, other native groups such as the Eskimos, Indians, and
Aleuts of Alaska, or the tribes of Puget Sound traditionally consume high quantities offish and fish
products. The U.S. indigenous populations are widely distributed geographically. For example, a U.S.
EPA report (1992b) identified 281 Federal Indian reservations that cover 54 million acres in the United
States. Treaty rights to graze i> vcstock, hunt, and fish are held by native peoples for an additional 100 to
125 million acres. There are an estimated two million American Indians in the United States (U.S. EPA,
4-34
-------
1992b). Forty-five percent of these two million native people live on or near reservations and trust lands.
High-end fish consuming groups include Alaska natives who number between 85,000 and 86,000 people
(Nobmann et al., 1992).
Fish products consumed by indigenous populations may rely on preparation methods that differ
from ones typically encountered in the diet of the general U.S. population. By way of illustration, food
intake data obtained from Alaskan natives were used to calculate nutrient intakes using a computer and
software program. These computerized databases had been developed by the U.S. Veterans
Administration (VA) for patients in the national Veteran's Administration hospital system. Nobmann et al.
(1992) found they needed to add data for 210 dietary items consumed by Alaskan Natives to the 2400 food
items in the VA files.
In the mid-1990s data on fish consumption by indigenous populations of the United States were
reported for Alaska Natives (Nobmann et al., 1992), Wisconsin Tribes (U.S. EPA, 1992), the Columbia
River Tribes (Columbia River Inter-Tribal Fish Commission, 1994) and selected Puget Sound Tribes (Toy
et al. 1995). Findings from these studies can be used to assess differences in fish consumption between
these indigenous groups and the general U.S. population.
Summary of Native American Angler Surveys
Table 4-30 summarizes the reported consumption rates of Native Americans detailed here.
Although not all Native American tribal groups traditionally include fish as part of their diets, groups
living near rivers, lakes, and coastal areas consume a vide variety of fish and shellfish. The highest levels
of fish and shellfish consumption are thought to occur among tribal groups living along the Pacific Coast
and in Alaska. Tribal groups in the Great Lakes region also include fish as part of their typical diet. The
data base to estimate quantities of fish consumed has been greatly enhanced over the past five years with
the publication of a number of dietary assessments conducted as part of activities to determine exposure to
chemical contaminants in fish.
Surveys of Native American anglers in the United States indicate an average fish/shellfish
consumption in the rage of 30 to 80 grams per day (U.S. EPA, 1992b; Hamly et al., ] 997; Toy et al., 1995)
with 90th percentile consumption of about 150 grams/day or higher (Toy et al., 1995). Inclusion of data
on Alaskan Native Americans results in still higher levels of fish and shellfish intake. For example,
Nobmann et al. (1992) reported mean fish consumption estimates in excess of 100 grams/day.
Table 4-30
Fish Consumption by Native U.S. Populations
Source
Nobmann
et al., 1992
U.S. EPA,
1992b
Population
35 1 Alaska Native
adults (Eskimos,
Indians, Aleuts)
Wisconsin Tribes 1 1
Native American
Indian Tribes
Percentile
Mean
Mean
Fish-Meals
Consumed or Fish
Consumption (gms)
109 gms offish and
shellfish per day.
32 gms of fish per day
Notes
4-35
-------
Table 4-30 (continued)
Fish Consumption by Native U.S. Populations
Source
Peterson et
al., 1995
Toy et al..
1995
Fitzgerald
et al., 1995
Population
323 Chippewa adults
> 1 8 years of age.
Tulalip and Squaxin
Island Tribes. 263
adult subjects.
97 nursing Mohawk
women
Percentile
Mean= 1.7 fish
meals/week.
(1.9 and 1.5 fish
meals/week for male
and for female
respondents,
respectively).
0.26% of males and
0.1 5% of females
reported eating 3 or
more fish-meals per
week.
50% of respondents
ate one or less fish
meals per week.
2 1 % of respondents
ate three or more fish
meals per week.
2% of respondents ate
fish-meals each day.
50th percentile:
Finfish, 22 gins/day;
total fish consumed,
43 gms/day.
90th percentile:
Finfish, 88 gms/day;
total fish, 156
gms/day.
24.7% ate 1-9 local
fish meals/year during
pregnancy;
10.3% ate >9 local
fish meals/year during
pregnancy;
4 1.2% ate 1-9 local
fish meals/year one
year prior to
pregnancy;
15.4% ate >9 local
fish meals/year one
year prior to
pregnancy;
Fish-Meals
Consumed or Fish
Consumption (gins)
Notes
Report contains
data for
anadromous fish,
pelagic, bottom
and shell fish.
Data are based on
an average body
weight of 70
kg/day.
Study conducted
from 1986-1992
in area where fish
are contaminated
with PCB
4-36
-------
Table 4-30 (continued)
Fish Consumption by Native U.S. Populations
Source
Centers for
Disease
Control,
1993
Gerstenber
ger et al.,
1997
Population
Miccouskee Indian
Tribes of South
Florida (1993), 2
children and 1 83
adults completed
dietary questionaires
89 Ojibwa Tribal
members from the
Great Lakes Region
Percentile
Fish-Meals
Consumed or Fish
Consumption (gins)
Local fish: 31% (58
persons) reported eating
fish from Everglades
during previous 6
months. Maximum
daily consumption: 168
grams Median daily
consumption: 3.5 grams
Marine fish: 57% (105
persons) consumed
marine fish during
previous 6 months.
Nonlocal freshwater
fish: 1 individual, 25
grams/day
Local wildlife: 65%
(120 participants)
consumed local game.
35% of respondents ate
Lake Superior fish
Ix/week. 6.7% ate
Lake Superior fish
2x/week.
Consumption of fish
from other lakes:
12.5% ate these
1 x/week
5.7% ate these 2x/week
89 respondents
averaged 29 fish
meals/year (range zero
to 150 fish meals/year)
Notes
Blue gill most
common species
of local fish
consumed.
Largemouth bass
consumed in
greatest quantity
Canned tuna most
commonly
consumed (by ail
105 of marine
consumers) and
in the largest
amounts (7.0
grams/day
median level)
Local game
consumed: deer
(57% of
participants),
wildboar(10%),
redbelly turtle
(10%), frog (5%)
and alligator
(3%)
Most frequently
consumed fish
from Lake
Superior: lake
trout (37%),
walleye (27%),
whitefish (27%).
From inland
lakes: Walleye.
Highest fish
consumption in
April, May, and
June
4-37
-------
Table 4-30 (continued)
Fish Consumption by Native U.S. Populations
Source
Harnly et
al., 1997
Population
Native Americans
living near Clear Lake
California
Percentile
Fish-Meals
Consumed or Fish
Consumption (gins)
Fish-consuming
participants averaged
60 g/day of sportfish
and 24 g/day of
commercial fish.
10% of adults
consumed Hg intakes >
30 |j g/day
Notes
Sportfish species:
catfish, perch,
hitch, bass, carp
Commercial fish:
snapper, tuna,
salmon, crab,
shrimp.
Wisconsin Tribes
An U.S. EPA report entitled Tribes at Risk (The Wisconsin Tribes Comparative Risk Project) (US
EPA, 1992) reported an average total daily fish intake for Native Americans living in Wisconsin of
35 gms/day. The average daily intake of locally harvested fish was 31.5 grams.
Peterson et al. (1995) surveyed 323 Chippewa adults over 18 years of age living on the Chippewa
reservation in Wisconsin. The survey was conducted by interview and included questions about season,
species and source of fish consumed. The survey was carried out in May. Fish consumption was found to
be seasonal with the highest fish consumption occurring in April and May. Fish species typically
consumed were walleye and northern pike, muskellunge and bass. During the months in which the
Chippewa ate the most fish, 50% of respondents reported eating one or fewer fish meals per week, 21%
reported eating three or more fish meals per week, and 2% reported daily fish consumption. The mean
number of fish meals per week during the peak consumption period was 1.7 meals; this is approximately
42% higher than the 1.2 fish meals per week that respondents reported as their usual fish consumption.
Higher levels of fish consumption were reported by males (1.9 meals per week) than by females (1.5 meals
per week). Among male respondents 0.26% ate 3 or more fish meals per week, whereas 0.15% of female
respondents ate 3 or more meals of fish per week. Unemployed persons typically had higher fish
consumption rates.
Columbia River Tribes
The Columbia River Inter-Tribal Fish Commission (1994) estimated fish consumption rates based
on interviews with 513 adult tribal members of four tribes inhabiting the Columbia River Basin (see Tables
4-31 and 4-32). The participants had been selected from patient registration lists provided by the Indian
Health Service. Data on fish consumption by 204 children under 5 years of age were obtained by
interviewing the adults.
Fish were consumed by over 90% of the population with only 9% of the respondents reporting no
fish consumption. The average daily consumption rate during the two highest intake months was 108
grams/day, and the daily consumption rate during the two highest and lowest intake months were 108
g/day and 31 g/day, respectively. Members who were aged 60 years and older had an average daily
consumption rate of 74 grams/day. During the past two decades, a decrease in fish consumption was
4-38
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generally noted among respondents in this survey. The maximum daily consumption rate for fish reported
for this group was approximately 970 grams/day.
Table 4-31
Fish Consumption by Columbia River Tribes
(Columbia River Inter-Tribal Commission, 1994)
Subpopulation
Total Adult Population, aged 1 8 years and older
Children, aged 5 years and younger
Adult Females
Adult Males
Mean Daily Fish Consumption (g/day)
59
20
56
63
Table 4-32
Daily Fish Consumption Rates by Adults of Columbia River Tribes
(Columbia River Inter-Tribal Commission, 1994)
Percentile
50th
90th
95th
99th
Amount (g/day)
29-32
97-130
170
389
Tribes of Puget Sound
A study of fish consumption among the Tulalip and Squaxin Island Tribes of Puget Sound was
completed in November 1994 (Toy et al., 1995). The Tulalip and Squaxin Island Tribes live
predominantly on reservations near Puget Sound, Washington. Both tribes rely on commercial fishing as
an important part of tribal income. Subsistence fishing and shell-fishing are significant parts of tribal
members economies and diets.
The study was conducted between February and April in 1994. Fish consumption practices were
assessed by questionnaire and interview using dietary recall methods, food models and a food frequency
questionnaire. The food frequency questionnaire was aimed as identifying seasonal variability. Questions
in the interview included food preparation methods and obtained information on the parts of the fish
consumed. Fish consumed were categorized into anadromous fish (king salmon, sockeye salmon, coho
salmon, chum salmon, pink salmon, steelhead salmon, salmon unidentified and smelt); pelagic fish (cod,
pollock, sable fish, spiny dogfish, rockfish, greenling, herring and perch); bottom fish (halibut,
sole/flounder and sturgeon); and shell fish (manila clams, little clams, horse clams, butter clams, cockles,
oysters, mussels, shrimp, dungeness crab, red rock crab, scallops, squid, sea urchin, sea cucumbers and
moon snails).
4-39
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Among consumers of anadromous fish, local waters (i.e., Puget Sound) supplied a mean of 80% of
the fish consumed. Respondents from the Tulalip Tribes purchased a mean of approximately two-thirds of
fish from grocery stores or restaurants, while among the Squaxin Island Tribe, the source of fish was about
50% self-caught and 50% purchased from grocery stores or restaurants. For bottom fish, members of both
tribes caught about half of the fish they consumed. Anadromous fish were much more likely to be
consumed with the skin attached. Most other fish were consumed minus the skin. Approximately 10% of
the respondents consumed parts of the fish other than muscle; i.e., head, bones, eggs.
Data on fish consumption were obtained for 263 members from the Tulalip and Squaxin Island
tribes. The mean consumption rate for women of both tribes was between 10-and-12-times higher than the
default rate of 6.5 grams/day used by some parts of the U.S. government to estimate fish intake. Among
male members of both tribes, the consumption rate was approximately 14-times higher than the default
rate. The 50th percentile consumption rate for finfish for both tribes combined was 32 grams/kg body
weight/day. Male members of the Tulalip and Squaxin Island tribes had average body weights of
189 pounds and 204 pounds, respectively. Female members of the Tulalip and Squaxin Island tribes
weighed on average 166 pounds and 150 pounds, respectively. If an average body weight is assumed to be
70 kg, the daily fish consumption rate for both tribes for adults was 73 grams per day with a 90th
percentile value of 156 grams per day for total fish. Fish consumption data for selected categories of fish
are shown in Table 4-33.
Table 4-33
Fish Consumption (gms/kg bw/day) by the Tulalip and Squaxin Island Tribes
(Toy et ah, 1995)
Type of
Fish
Anadromous
Pelagic
Bottom
Shell
Fish
Other
Fish
Total
Finfish
Total
All Fish
5th
Percentile
.0087
.0000
.0000
.0000
.0000
.0200
.0495
50th
Percentile
.2281
.0068
.0152
.1795
.0000
.3200
.6081
90th
Percentile
1 .2026
.1026
.1095
1.0743
.0489
.1350
2.2267
95th
Percentile
1.9127
.2248
.2408
1.4475
.1488
2.1800
3.2292
Mean
.4600
.0390
.0482
.3701
.0210
.5745
1.0151
SE
.0345
.0046
.0060
.0343
.0029
.0458
.0865
95th
Percent CI
.3925. 0.5275
.0300. 0.0480
.0364. 0.4375
.3027, 0.4375
.0152,0.0268
.4847, 0.6643
.8456, 1.1846
During the survey period, 21 of the 263 tribal members surveyed reported fish consumption rates
greater than three standard deviations from the mean consumption rate. For example, six subjects reported
consumptions of 5.85, 6.26, 9.85, 11.0, 22.6 and 11.2 grams of finfish and shell fish/kg body weight/day.
If a 70-kg body weight is assumed these consumption rates correspond to 410, 438, 690, 770 and 1582
grams per day.
4-40
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Mohawk Tribe
A study of fish consumption among 97 nursing Mohawk women in rural New York State was
conducted from 1986 to 1992 (Fitzgerald et al., 1995). Fish consumption advisories had been issued in the
area due to polychlorinated biphenyl (PCB) contamination of the local water body. Using food frequency
history and a long-term dietary history, the women were asked about their consumption of locally caught
fish during three specific periods of time: during pregnancy, the year prior to pregnancy, and more than a
year before pregnancy. For comparison, the study also surveyed fish consumption rates among 154
nursing (primarily Caucasian) women from neighboring counties. The socioeconomic status of the women
of the control group were similar to that of the Mohawk women. The fish in these counties had
background PCB concentrations.
The results (Table 4-34) showed that the Mohawk women had a higher prevalence of consuming
locally caught fish than the comparison group in the two intervals assessed prior to the pregnancy; the
prevalence of local fish consumption during pregnancy for the two groups was comparable. A decrease in
local fish consumption rates was also noted over time; these may be related to the issuance of advisories.
Table 4-34
Local Fish Meals Consumed By Time Period for the
Mohawk and Comparison Nursing Mothers (Fit/gerald et al., 1995)
Fish Meals/
Year
0
1-9
10-19
>19
During Pregnancy
Mohawk
64.9%
24.7%
5.2%
5.1%
Control
70.8%
15.6%
4.5%
9.1%
1 Year Before Pregnancy
Mohawk
43.3%
41.2%
4.1%
1 1 .3%
Control
64.3%
20.1%
3.9%
11.7%
>1 Year Before Pregnancy
Mohawk
20.6%
43.3%
6.2%
29.9%
Control
60.4%
22.7%
5.2%
1 1 .7%
Native Americans near Clear Lake, California
Harnly et al. (1997) found that Native Americans living near Clear Lake, California consumed an
average of 84 grams of fish/day (60 g/day sport fish plus 24 g/day of commercial fish). Ten percent of
adults reported mercury intakes over 30 ug/day. The most popular species of sportfish were: catfish,
perch, hitch, bass, and carp. Commercial species most commonly eaten were: snapper, tuna, salmon, crab,
and shrimp.
Great Lakes Tribes
Members of the Ojibwa live in the Great Lakes region of the United States and Canada.
Gerstenberger et al. (1997) reported that approximately 35% of the respondents (89 members of the
Ojibwa Tribes) consumed Lake Superior fish at least once a week with 7% of this group consuming Lake
Superior fish at least twice a week. The most commonly consumed Lake Superior-origin fish were lake
trout, walleye, and whitefish. In addition, fish were consumed from inland lakes with ] 2% of reponsdnets
4-41
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eating inland lake fish once a week and 6% consuming these fish twice a week. Walleye was the most
common species offish consumed from these inland lake sources.
4.1.4 Summary of Hawaiian Island Fish Consumption Data
The CSFD 1989-1991 did not include the Hawaiian Islands. To the knowledge of the authors of
the Mercury Study Report to Congress, data describing fish consumption by the general Hawaiian
population that estimate Island-wide levels of consumption have not been reported. However, reports on
commercial utilization of seafood (Higuchi and Pooley, 1985; Hudgins, 1980) and analysis of
epidemiology data (Wilkens and Hankin, personal communication, 1996) provide a basis to describe
general patterns of consumption. Overall, seafood consumption in Hawaii is much higher than in the
contiguous United States. On a per capita basis, the United States as a whole consumed 5.45 kg and 5.91
kg (12 and 13 pounds) of seafood in 1973 and 1977, respectively (Hudgins, 1980). By contrast Hawaiian
per capita consumption for all fish products was 11.14 kg (24.5 pounds) in 1972 and 8.77 kg (19.3
pounds) in 1974.
The most popular species of fish and shellfish consumed were moderately comparable between
Hawaii and the contiguous 48 states. The methods of food preparation differed, however, with raw fish
being far more commonly consumed in Hawaii. Sampled at the retail trade level the most commonly
purchased fish were: tuna, mahimahi, and shellfish [see Table 4-35 which is based on data in Higuchi and
Pooley (1985)]. A survey of seafood consumption by families was identified. In 1987, the Department of
Business and Economic Development (State of Hawaii, 1987) conducted a survey of 400 residents selected
on a random digit dialing basis of a population representing 80% of total state seafood consumption. All
data were collected in July and August, 1987 and would not reflect any seasonal differences in
fish/shellfish consumption. The respondents were asked to describe seafood consumption by their
families. Shrimp was the most popular seafood with mahimahi or dolphin fish as the second most popular
(Hawaii Seafood, 1988). Reports on fish consumption in Hawaii separate various species of tuna: ahi
(Hawaiian yellowfm tuna, bigeye tuna & albacore tuna), aku (Hawaiian skipjack tuna), and tuna. In 1987,
nearly 66% of the 400 families surveyed had seafood at least once a week and 30% twice a week. Only
4% did not report consuming seafood during the previous week based on a telephone survey.
Wilkens and Hankin (personal communication, 28 February 1996) analyzed fish intake from 1856
control subjects from Oahu who participated in research studies conducted by the Epidemiology Program
of the Cancer Research Center of Hawaii, University of Hawaii at Manoa. These subjects were asked
about consumption over a one-year period prior to the interview. Within this group the most commonly
consumed fish was tuna [canned with tuna species undesignated (70.8 % of subjects reporting
consumption)]: shrimp (47.7% of subjects); tuna (yellowfm fresh designated aku. ahi with 42.2% of
subjects reporting consumption); mahimahi [(or dolphin) with 32.5% of respondents reporting
consumption]; and canned sardines (with 29.1 % of subjects reporting consumption).
4-42
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Table 4-35
Species Composition of Hawaii's Retail Seafood Trade 1981 Purchases
Higuchi and Pooley (1985)
Fish/Shellfish
Tuna
Ahi (Hawaiian yellow-
fin, bigeye & albacore)
Billfish (including swordfish)
and shark
Mahimahi and ono (wahoo)
Akule (Hawaiian bigeye scad)
and opelu
Bottom fish
Reef fish
Shellfish
Shrimp
Lobster
Other species
Salmon/trout
Snapper
Frozen filets
Frozen sticks/blocks
Total
Pounds Purchased
11,600,000
(5,400,000)
5,900,000
9,900,000
4,00,000
2,600,000
3,500,000
8,200,000
(4,200,000)
(900,000)
8,300,000
(1,500,000)
(1,800,000)
(2,300,000)
(1,400,000)
54,000,000
Percent of Total Purchases
20.9
11.3
17.7
6.9
7.0
5.3
15.5
15.4
100.0
4.1.5 Summary of Alaskan Fish Consumption Data
The CSFII analyses of food intake by the USDA include the 48 contiguous states but do not
include Alaska or Hawaii. A number of investigators have published data on fish consumption in Alaska
by members of native populations (e.g., Inuits, Eskimos) and persons living in isolated surroundings.
These reports focus on nutritional/health benefits of high levels offish consumption, food habits of native
populations, and/or effects of bioaccumulation of chemicals in the aquatic food web.
4.1.5.1 General Population
After contacting professionals from the Alaskan health departments and representatives of the U.S.
Centers for Disease Control in Anchorage, the authors of this report have not identified general population
data on fish consumption among Alaskan residents who are not part of native population groups,
subsistence fishers/hunters, or persons living in remote sites. Patterns of fish consumption among urban
residents (e.g., Juneau, Nome, Anchorage) appear not to be documented in the published literature.
4-43
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4.1.5.2 Non-urban Alaskan Populations
Native people living in the Arctic rely on traditional or "country" foods for cultural and economic
reasons. The purpose of the current discussion is not to assess the comparative risks and benefits of these
foods. The risks and benefits of these food consumption habits have been compared by many investigators
and health professionals (among others see Wormworth, 1995; Kinloch et al., 1992; Bjerregaard, 1995).
Despite a degree of acculturation in the area of foods, native foods were still eaten frequently by
Alaskan Native peoples based on results of the 1987-1988 survey. Diets that include major quantities of
fish (especially salmon) and sea mammals retain a major place in the lives of Alaskan Native peoples. The
consumption of traditional preparations of salmon and other fish continues; this includes fermented foods
such as salmon heads and eggs, other fish and their eggs, seal, beaver, caribou and whale.
Diets of Native Alaskans differ from the general population and rely more extensively on fish and
marine mammals. These are population groups that are characterized by patterns of food consumption that
reflect availability of locally available foods and include food preparation techniques that differ from those
usually identified in nutrient data bases. For example, Nobmann et al. (1992) surveyed a population of
Alaska Natives that included Eskimos (53%), Indians (34%), and Aleuts (13%). The distribution of study
participants was proportional to the distribution of Alaska Natives reported in the 1980 Census. The 1990
Census identified an overall population of 85,698 persons as Alaska Natives.
Nobmann et al. (1992) indicated that Alaska Natives have traditionally subsisted on fish; marine
mammals; game; a few plants such as seaweed, willow leaves, and sourdock; and berries such as
blueberries and salmonberries rather than on a plant-based diet. In preparing a nutrient analysis of the food
consumed in eleven communities that represented different ethnic and socioeconomic regions of Alaska,
these investigators added nutrient values for 210 foods consumed by Alaska Natives in addition to the
2400 foods present in the Veteran's Administration's nutrient data base. Nobmann et al. (1992) found fish
were an important part of the diet. The mean daily intake offish and shellfish of Alaska Natives was 109
grams/day. Fish consumption was more frequent in the summer and fall and game meat was eaten more
often in the winter.
Quantitative information on dietary intakes of Native Alaskan populations are few. Estimates can
be derived from harvest survey data, but these have limitations because not all harvested animals are
consumed nor are all edible portions consumed. Other edible portions may be fed to domestic animals
(e.g., sled dogs). Substantial variability in intake of foods including ringed seal, bearded seal, muktuk
(beluga skin with an underlying thin layer of fat) and walrus has been reported (Ayotte et al., 1995).
Dietary analyses on seasonal food intakes of 351 Alaska Native adults from eleven communities
were performed during 1987-1988 (Nobmann et al., 1992). Alaska Natives include Eskimos, Indians and
Aleuts. There is no main agricultural crop in Alaska which when combined with a short growing season,
results in limited availability of edible plants. Alaska Natives have traditionally relied on a diet offish, sea
mammals, game and a few native plants (seaweed, willow leaves, and sourdock) and berries (such as,
blueberries and salmon berries). Although consumption of significant amounts of commercially produced
foods occurs, use of subsistence foods continues.
The survey sample of 351 adults, aged 21-60 years, was drawn from eleven communities.
Information was obtained using 24-hour dietary recalls during five seasons over an 18-month period. Fish
were consumed much more frequently by Alaska Natives than by the general U.S. population. Fish ranked
as the fourth most frequently consumed food by Alaska Natives compared with the 39th most frequently
consumed food by participants in the nationally representative Second National Health and Nutrition
Assessment Survey (NHANES II). The mean daily intake of fish and shellfish for Alaska Natives was 109
4-44
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grams/day contrasted with an intake of 17 grams per day for the general U.S. population described in
NHANES n. Among Alaska Natives fish was consumed more frequently in the summer and fall months.
Several extensive data sets on mercury concentrations in marine mammals consumed by
indigenous populations living in the circumpolar regions have been published (Wagemann et al., 1996;
Caurant et al., 1996; Dietz et al., 1996). Analyses that determined chemically speciated mercury have
shown that mercury present in muscle tissue is largely (>75%) organic mercury (i.e., methylmercury
(Caurant et al., 1996)). By contrast, mercury present in organs such as liver and kidney is predominantly
in an inorganic form (Caurant et al., 1996).
4.1.5.3 Alaskans from Subsistence Economies
Wolfe and Walker (1987) described the productivity and geographic distribution of subsistence
economies in Alaska during the 1980s. Based on a sample of 98 communities, the economic contributions
of harvests of fish, land mammals, marine mammals and other wild resources were analyzed.
Noncommercial fishing and hunting play a major role in the economic and social lives of persons living in
these communities. Harvest sizes in these communities were established by detailed retrospective
interviews with harvesters from a sample of households within each community. Harvests were estimated
for a 12-month period. Data were collected in pounds of dressed weight per capita per year. Although it
varies by community and wildlife species, generally "dressed weight" is approximately 70 to 75% of the
round weight for fish and 20 to 60% of round weight for marine animals. Dressed weight is the portion of
the kill brought into the kitchen for use, including bones for particular species. The category "fish"
contains species including salmon, whitefish, herring, char, halibut, and pike. "Land mammals" included
species such as moose, caribou, deer, black bear, snowshoe and tundra hare, beaver and porcupines.
"Marine mammals" consisted of seal, walrus and whale. "Other" contained birds, marine invertebrates,
and certain plant products such as berries.
Substantial community-to-community variability in the harvesting offish, land mammals, marine
mammals and other wild resources were noted (Wolfe and Walker, 1985). Units are pounds "dressed
weight" per capita per year. The median harvest was 252 pounds with the highest value approximately
1500 pounds. Wild harvests (quantities of fish, land mammals and marine mammals) in 46% of the
sampled Alaskan communities exceeded the western U.S. consumption of meat, fish, and poultry. These
communities have been grouped by general ecological zones which correspond to historic/cultural areas:
Arctic-Subarctic Coast, Aleutian-Pacific Coast, Subarctic Interior, Northwest Coast and contemporary
urban population centers. The Arctic-Subarctic Coast displayed the greatest subsistence harvests of the
five ecological zones (610 pounds per capita), due primarily to the relatively greater harvests of fish and
marine animals. For all regions the fishing output is greater than the hunting; fishing comprises 57 - 68%
of total subsistence output. Above 60° north latitude fishing predominates other wildlife harvests, except
for the extreme Arctic coastal sea mammal-caribou hunting communities. Resource harvests of fish
("dressed weight" on a per capita basis) by ecological zone (and cultural area) were these: Arctic-Subarctic
Coast (Inupiaq-Yup'ik), 363 pounds/year or 452 grams/day; Aleutian-Pacific Coast (Aleut-Sugpiaq), 251
pounds/year or 312 grams/day; Subarctic Interior (Athapaskan), 256 pounds/year or 318 grams/day;
Northwest Coast (Tingit-Haida), 122 pounds/year or 152 grams/day; and Other (Anchorage, Fairbanks,
Juneau, Matanuska-Susitna Borough, and Southern Cook Inlet), 28 pounds/year or 35 grams/day.
Consumption of marine mammals was reported among Yupik Eskimos living in either a coastal or
river village of southwest Alaska (Parkinson et al., 1994). Concentrations of plasma omega-3 fatty acids
were elevated (between 6.8 and 13 times) among the Yupic-speaking Eskimos living in two separate
villages compared with non-Native control subjects (Parkinson et al., 1994). Concentrations of omega-3
fatty acids in plasma phospholipid has been shown to be a valid surrogate offish consumption (Silverman
4-45
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et al., 1990). Among coastal-village participants the concentrations of eicosapentaonoic and
docosahexaenoic acids reflected higher consumption of marine fish and marine mammals and the use of
seal oil in food preparation. Among river village natives, the increase reflected higher consumption of
salmon.
The Division of Subsistence of the Alaska Department of Fish and Game (Robert J. Wolfe,
personal communications, 1997) has provided estimates of the mean per capita harvests of subsistence fish,
shellfish, and marine mammals in rural Alaska areas (Table 4-36). Combined harvests of
fish/shellfish/marine mammals averaged approximately 350 grams/day for all rural areas combined. The
highest intakes were found in the Western, Interior and Arctic regions with harvests of 693, 577, and 482
grams/day, respectively. Marine mammal consumption was particularly high in the Arctic region with an
average of approximately 270 grams/day consumed. Comparable estimates of marine mammal
consumption were reported by Chan (1997) for an Inuit community based on dietary information gathered
by the Centre for Indigenous Peoples' Nutrition and the Environment (Table 4-37). Using the Centre's
database for contaminants, Chan estimated that mercury intakes were 185 ug mercury/day with 170 ug of
mercury coming from marine mammal meat.
Consumption of marine mammals results in very high exposures to methylmercury. Wolfe (1997)
provided data on mean per capita harvest of marine mammals in the Arctic region of rural Alaska of about
290 grams/day. Greater details of types of marine mammals consumed, mercury concentrations found in
these mammals, and estimates of quantities of mammals consumed have been published by Canadian
investigators (Jensen et al. 1997; Chan, 1997) and by the investigators in Greenland and Denmark (Dietz et
al., 1996).
Table 4-36
Mean Per Capita Harvest of Fish and Marine Mammals (g/day)
(Wolfe, personal communication, 1997)
Alaska Rural Area
Southcentral-Prince
William Sound
Kodiak Island
Southeast
Southwest-Aleutian
Interior
Arctic
Western
All Rural Areas
Combined
Fish
114
132
119
299
577
194
605
276
Shellfish
7
17
32
7
0
1
0
11
Marine
Mammals
4
2
7
12
0
267
88
65
Fish/Shellfish
122
149
152
307
577
195
605
267
Fish/Shellfish/
Marine
Mammals
126
152
159
319
577
482
693
352
4-46
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Table 4-37
Estimated Daily Intake of Food and Mercury for Arctic Inuit
(Adapted from Chan, 1997)
Food group
Marine mammal meat
Marine mammal blubber
Terrestrial mammal meat
Terrestial mammal organs
Fish
Birds
Plants
Total
Food (g/day)
199
30
147
1
42
2
2
423
Mercury (ug/day)
170
2.4
4.0
0.9
6.6
0.8
0.0
185
Marine mammals are primarily exposed to methylmercury (Caurant et al., 1996). Mercury present
in flesh of marine mammals is largely methylmercury. For example, Caurant et al. (1996) identified an
average of 78% organic mercury in muscle of pilot whales (Globicepala melas) and 23% organic mercury
in pilot whale liver. Mercury in organs such as liver and kidney appears to be demethylated and stored in a
form combined with selenium, which has been regarded as a detoxification mechanism for the marine
mammals (Caurant et al., 1996). Detailed date on mercury concentration in the northern marine ecosystem
were reported by Dietz et al. (1996) including information on mercury concentration in molluscs,
crustaceans, fish, seabirds, seals, whales, and polar bears.
Among the Inuit in coastal communities of the Canadian Arctic and Greenland, marine mammals
are an important source of food. Food items include the flesh and some organs of ringed seals (Phoca
hispida) and the flesh, but preferentially skin meat and liver of ringed seals and muktuk and blubber of
whales are eaten raw or cooked. Muktuk and the flesh, liver, intestines, and blubber of walrus are also
eaten after fermentation (Wagemann et al., 1996).
Throughout the Arctic, the mean mercury concentration in muscle of beluga whale averaged
between 0.7 and 1.34 ug mercury/gram wet weight of tissue (Wagemann et al., 1996). Muktuk (skin as a
whole) of beluga averaged between approximately 0.6 and 0.8 jag mercury/g wet weight. The skin of
cetaceans (whales, dolphins, porpoises) consists of four layers with the mercury concentration increasing
toward the outermost layers of skin. In this outermost layer of skin, mercury concentration were about 1.5
ug/gram. During molting, about 20% of the total mercury in skin is lost annually. Muscle tissue of
narwhal averaged between 0.8 and 1.0 pg/g, while muktuk averaged around 0.6 ug/g wet weight
(Wagemann et al., 1996). Muscle flesh of ringed seals had average mercury concentrations in the range of
0.4 and 0.7 ug/g with most of the mercury present as methylmercury. Liver mercury concentrations
averaged in the range of 20 to 30 ug/g, but this was primarily present as inorganic mercury. Kidney
contained between 1 and 3 ppm mercury (Wagemann et al., 1996).
Overall, groups consuming muscle and muktuk from marine mammals have much higher
exposures to methylmercury that do groups who consume primarily fish and/or terrestrial mammals. Chan
4-47
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(in press) estimated exposures over 180 fig mercury/day for Arctic Inuits. To whatever extent organs
(specifically liver and kidney) are consumed, these typically contain higher concentrations of mercury but
with a lower fraction of methylmercury than found in muscle tissue.
4.1.6 Summary of Canadian Data on Mercury Intake from Fish and Marine Mammals
The Northern Contaminants Program on the Department of Indian Affairs and Northern
Development of the Canadian Government published a compilation of contaminant data including mercury
concentrations in fish and marine mammals (Jensen et al., 1997). Most of the traditionally harvested fish
and land and marine animals consumed are long-lived and are from the higher trophic levels of the food
chain which contain greater concentrations of methylmercury than are found in nonpredatory fish.
Several extensive data sets on mercury concentrations in marine mammals consumed by
indigenous populations living in the circumpolar regions have been published (Wagemann et al., 1996;
Caurant et al., 1996; Dietz et al., 1996). Analyses that determined chemically speciated mercury have
shown that mercury present in muscle tissue is largely (>75%) organic mercury (i.e., methylmercury)
(Caurant et al., 1996). By contrast, mercury present in organs such as liver and kidney is predominantly in
an inorganic form (Caurant et al., 1996).
Wagemann et al. (1997) have provided an overview of mercury concentrations in Arctic whales
and ringed seals. The Inuit in coastal communities of the Canadian Arctic and Greenland hunt and
consume marine mammals for food. The flesh and some organs of ringed seals (Phoca hispida) and flesh
but preferentially skin (muktuk) of belugas (Delphinapterus leucas) and narwal (Monodon monoceros)
contribute significantly to the Inuit diet. Throughout the Arctic, the mean concentrations in Beluga muscle
averaged 0.70 to 1.34 ug mercury/gram wet weight (Wagemann et al., 1996). Mean mercury
concentrations in the muktuk (skin as a whole) of belugas sampled in the western (1993-1994) and the
eastern Arctic (1993-1994) were 0.78 and 0.59 ug mercury/gram wet weight (Wagemann et al., 1996).
Mean mercury concentrations for narwhal samples collected in the period 1992-1994 were 0.59, 1.03,
10.8, and 1.93 ug mercury/gram wet weight in muktuk, muscle, liver, and kidney, respectively (Wagemann
et al., 1996). Muscle tissue of ringed seals contained mercury in concentrations averaging between 0.4 and
approximately 0.7 ug mercury/gram wet weight. Liver tissue averaged between approximately 8 and 30
Ug mercury/gram wet weight. Kidney tissues averaged between 1.5 and 3.2 (jg mercury/gram wet weight.
Extensive data on mercury concentrations in multiple tissues from a wide variety of molluscs,
Crustacea, fish, seabirds, and marine mammals (seals, whales, and porpoises), and polar bears collected in
Greenland were published by Dietz et al. (1996). Chemically speciated mercury concentrations in tissues
of pilot whales have been determined by Caurant et al. (1996). The percent organic mercury (i.e.,
methylmercury) in muscle tissue averaged over 75%. Liver contained a smaller fraction organic mercury,
averaging approximately 23% organic mercury. Marine mammals are principally exposed to
methylmercury, which is the main physico-chemical form of storage in fish (Caurant et al., 1996).
Although demethylation by liver may serve as a means of protecting the marine mammal against adverse
effects of methylmercury, the presence of organic mercury in the marine mammal's muscle means that
consumption of flesh from these mammals will result in exposure to organic mercury.
Jensen et al. (1997) in the Canadian Arctic Contaminants Assessment Report identified wide
variability in the consumption offish and marine mammals by various aboriginal groups. Chan (1997)
summarized results from an extensive number of dietary surveys of Northern peoples from the Dene
(registered Indian) communities and the Inuit communities (Tables 4-38 and 4-39). The Dene were
estimated to have a mean consumption of 80 grams/day of fish. The Inuit communities were estimated to
have a fish consumption of 42 grams/day, a marine mammal consumption of approximately 230 grams/day
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Table 4-38
Mercury Concentrations (ug Hg/g wet weight) in Traditional Foods Consumed
by Canadian Aboriginal Peoples
(Modified from Chan, 1997)
Food Group
Marine Mammal Meat
Marine Mammal
Blubber
Terrestrial Mammal
Meat
Terrestrial Mammal
Organs
Fish
Birds
Plants
Number of
Sites
32
6
6
14
799
24
8
Number of
Samples
764
71
19
254
31,441
216
34
Arithmetic
Mean
0.85
0.08
0.03
0.86
0.46
0.38
0.02
Standard
Deviation
1.05
0.05
0.02
0.90
0.52
0.59
0.02
Maximum
33.4
0.13
0.17
3.06
12.3
4.4
0.05
Table 4-39
Estimated Daily Intake of Mercury Using Contaminant Data Base and Dietary Information from
Dene and Inuit Communities in Canada
(Adapted from Chan, 1997)
Food Group
Marine Mammal Meat
Marine Mammal Blubber
Terrestrial Mammal Meat
Terrestrial Mammal Organs
Fish
Birds
Plants
Total
Dene Community
Food
(g/day)
0
0
205
23
80
8
2
318
Mercury
(y g/day)
0
0
6
20
13
1
0
40
Inuit Community
Food
(g/day)
199
30
147
1
42
2
2
423
Mercury
(ug/day)
170
2
4
1
7
1
0.0
185
(199 grams of meat and 30 grams of blubber). These mean consumptions were associated with a mercury
intake of 39 jag mercury/day for the Dene community and 185 u.g mercury/day for an Inuit community.
For the Inuit community, 170 jjg mercury/day came from marine mammal meat.
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4.2 Trends in Fish and Shellfish Consumption in the United States
Description of long-term trends in fish and shellfish consumption are based on data provided by
the National Marine Fisheries Service of the U.S. Department of Commerce. Detailed information on
trends in the 1990s, and forecasts for future production and consumption of fish and shellfish, are based on
projections described in the Annual Report on the United States Seafood Industry published by H.M.
Johnson & Associates (1997).
4.2.1 Fish and Shellfish Consumption: United States. 1975 to 1995
Data for the U.S. consumption and utilization of fish and shellfish have been obtained from the
World Wide Web (http://remora.ssp.mnfs.gov/commercial/landings/index.html). Landings are reported in
pounds of round (i.e., live) weight for all species or groups except univalve and bivalve molluscs, such as
clams, oysters, and scallops. For the univalves and bivalve molluscs, landings are reported as pounds of
meat which excludes shell weight. Landings to not include aquaculture products except for clams and
oysters. Aquaculture products are an increasing source of fish and shellfish for some species of seafood
(Johnson 1997).
U.S. per capita consumption of commercial fish and shellfish has increased from the early part of
this century until present. The major increases occurred post-1970. In 1910, for example, U.S. citizens
consumed an average of 11.0 pounds (edible meats) of commercial fish and shellfish. The consumption in
1970 was 11.8 pounds per capita, but by 1990 had increased to 15.0 pounds per capita.
Two major differences are associated with this trend. First, there was a major increase in
population from 92.2 million persons in 1910, to 201.9 individuals in 1970s, and 247.8 million citizens in
1990. In 1995 (the latest year this source provide statistics), the civilian resident population was estimated
at 261.4 million persons. Combined with increased consumption on a per capita basis, the seafood market
has dramatically increased throughout this century.
The second major change was in availability of transportation and in food processing. Changes
between 1910 and 1995 are shown in Table 4-40. Consumption of cured fish dramatically decreased from
about 36% of per capita intake in 1910, to 2.0% in 1990. Fresh or frozen fish were about 40% of per
capita intake in 1910 and increased to about 67% (two-thirds) of fish and shellfish intake by 1990 and
1995. The consumption of canned fish and shellfish changed the least representing about one-fourth of all
fish/shellfish intake in 1910 and about one-third of intake in 1990 and 1995.
Table 4-40
Percent of Fish/Shellfish by Processing Type between 1910 and 1995
(Source: National Marine Fisheries Service, 1997)
Year
1910
1970
1990
1995
Fresh/Frozen
39.1
58.5
64.7
66.7
Canned
24.5
38.1
33.3
31.3
Cured
36.4
4.0
2.0
2.0
4-50
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4.2.1.1 United States: Major Imports and Exports of Fish and Shellfish
During the period 1990 through 1994 the United States was the second largest importer of seven
fishery commodity groups, as well as the second largest exporter of these groups. The largest importer was
Japan and the third largest importer (after the United States) was France followed by Spain, Germany, and
Italy. On a value basis, Canada in the second largest trading partner for the United States after Japan
(Johnson, 1997).
The top five exporters of seafood were Thailand, United States, Norway, Denmark, and China.
Thailand is the leading supplier of seafood to the United States on a value basis, shipping primarily shrimp
(Johnson, 1997). Canada was the leading seafood supplier on a volume basis (Johnson, 1997). The seven
fishery commodity groups are:
1. Fish, fresh, chilled or frozen;
2. Fish, dried, salted, or smoked;
3. Crustaceans and mollusks, fresh, dried, salted, etc.;
4. Fish products and preparations, whether or not in airtight containers;
5. Crustacean and mollusk products and preparations, whether or not in airtight containers;
6. Oils and fats, crude or refined, or aquatic animal origin; and
7. Meals, soluble and similar animal food stuffs of aquatic animal origin.
4.2.1.2 U.S. Supply of Edible Commercial Fishery Products: 1990 and 1995
The supply of the products shown in Table 4-41 is expressed as round or live weight. Any
comparison of these values with food consumption data must consider that the edible portion is smaller
than the live weight. Factors for edible portion compared with live/round weight were published in the
National Research Council's report on Seafood Safety (NRC/NAS, 1990). Total U.S. consumption offish
and shellfish must also include self-caught and recreationally caught fish, as well as other sources that are
not tabulated through commercial channels.
Table 4-41
U.S. Supply of Edible Commercial Fishery Products: 1990 and 1995
(Round or Live Weight in Million Pounds)
Source: National Marine Fisheries Service
Year
1990
1995
Domestic Commercial
Landings
Million
Pounds
7,041
7,783
Percent
55.6
56.8
Imports
Million
Pounds
5,621
5,917
Percent
44.4
43.2
Total
Million
Pounds
12,662
13,700
4-51
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4.2.1.3 U.S. Annual Per Capita Consumption of Canned Fishery Products: 1990 and 1995
Canned tuna is the predominant type of canned fish consumed in the United States averaging
72.4% of all canned fish consumed per capita. Table 4-42 shows U.S. annual per capita consumption of
canned fishery products in 1990 and 1995.
Table 4-42
U.S. Annual Per Capita Consumption of Canned Fishery Products: 1990 and 1995
(Pounds Per Capita)
Year
1990
1995
Salmon
0.4
0.5
Sardines
0.3
0.2
Tuna
3.7
3.4
Shellfish
0.3
0.3
Other
0.4
0.3
Total
5.1
4.7
4.2.1.4 U.S. Annual Per Capita Consumption of Fish Items: 1990andl995
In fresh and frozen fish products and shrimp, per capita consumption in these categories is shown
in Table 4-43 based on data from the National Marine Fisheries Service.
Table 4-43
U.S. Annual Per Capita Consumption (in pounds*) of Certain Fishery Items: 1990 and 1995
Year
1990
1995
Fillet and Steaks **
3.1
2.9
Sticks and Portions
1.5
1.2
Shrimp
(All Preparations)
2.2
2.5
* Product weight of fillets and steaks and sticks and portions, edible (meat) weight of shrimp.
** Data include ground fish and other species. Data do not include blocks, but fillets could be made into blocks
from which sticks and portions could be produced.
4.2.1.5 Major Imported Fish and Shellfish Products
The two major fish/shellfish products imported into the United States in 1994 and 1995 (expressed
by weight) were shrimp (621,618,000 pounds in 1994 and 590,634,000 pounds in 1995), and tuna
(including albacore, canned tuna, and other tuna: 707,426,000 pounds in 1994 and 711,241,000 pounds in
1995). Approximately 28% of imported tuna was imported as albacore tuna and about 33% was imported
as canned tuna. Shrimp imports were not differentiated by species of shrimp or country of origin in the
national Marine Fisheries Service statistics.
4-52
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4.2.2 Current Market Trends. 1996
The following data on current market trends in the seafood industry are abstracted from the 7997
Annual Report on the United States Seafood Industry describing 1996 data on seafood by H.M. Johnson &
Associates (Johnson, 1997).
The world commercial fish and shellfish supplies increased from 109.6 thousand metric tons in
1994 to 112.0 thousand metric tons in 1995. Aquaculture provided the largest boost to world supply in
1995 increasing 13.6% over the previous year. During this period (1995 to 1996) capture fisheries
declined by 0.1 metric tons. Aquaculture represents 26% of all world food fish (total supply less reduction
fish) products.
The Food and Agriculture Organization examined long-term trends in 77 major fish resources
(representing 77% of the world marine fish landings) are concluded that 35% of the resources were
"overfished," 25% were "fully fished," and 40% had remaining capacity for expansion (FAO, 1996; as
cited by Johnson, 1997).
Aquaculture
World aquaculture continued to increase with 1995 production increased by 14% to 20.9 million
metric tons (Johnson, 1997). Five Asian countries (China, India, Japan, Republic of Korea, and the
Philippines) supplied 80% of aquaculture-raised fish/shellfish. World-wise aquaculture is predicted by the
Food and Agriculture Organization to continued to increase fish and shellfish production beyond the years
2000.
Within the United States, domestic finfish aquaculture increased in 1996. The major increases
were in catfish production. Catfish production very much dominates the U.S. finfish aquaculture
production yielding approximately 475 million pounds round weight/year. Tilapia harvests were higher in
1996, however, trout and salmon production declined. Salmon, trout, and tilapia production are
substantially smaller than catfish production. Yields from U.S. aquaculture for salmon, trout, and tilapia
were under 50 million pounds for each of these species.
4.2.3 Patterns in Fish and Shellfish Consumption: United States. 1996
4.2.3.1 Overall Patterns
Between 1995 and 1996 there was a 0.2 pound decrease in per capita consumption of seafood in
the United States. The principal decline was in canned tuna. The top ten seafoods consumed (expressed
as pounds consumed per capita) were: canned tuna (3.2), shrimp (2.5), Alaska Pollock (1.6); salmon (L4);
cod (just under 1 pound); catfish (approximately 0.9 pounds); clams (approximately 0.5 pounds), flatfish
(0.4 pounds), crab (approximately 0.3), and scallops (0.3). The source of these data are the National
Marine Fisheries Service and the 1997 Annual Report on the United States Seafood Industry (Johnson,
1997).
4.2.3.2 Fish Intake among Adults
Analysis of the frequency of reporting of fish/shellfish and menu items containing fish and
shellfish was carried out using data from CSFJJ 1994 and CSFJJ 1995. Seasons were grouped into six two-
month intervals; i.e., Jan/Feb, Mar/Apr, etc. Data for the 10 most commonly consumed menu items are
shown in Table 4-44. The most frequently reported menu items are "seafood salads and seafood and
4-53
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vegetable dishes." Although other fishery products are possible, this menu category typically describes
dishes made with tuna, surimi (i.e., Alaska pollock), crab, salmon or other canned fish or shellfish.
Overall, these dishes represent about 20% of overall seafood consumption. This major group is followed
by shrimp, canned tuna, the group "Seafood cakes, fritters, and casseroles without vegetables". Identified
fmfish commonly consumed include salmon, cod, catfish, flounder, trout, seabass, ocean perch, haddock,
and porgy. Although specific finfish are identified as among the top ten consumed over six seasons, they
follow consumption of processed fishery products; e.g., salads, fritters, "fast food" fillets, and shrimp.
Table 4-44
Ten Most Commonly Reported Fish/Shellfish/Mixed Dishes by Season
CSFII1994 and CSFII1995 Day 1 Data
D I *
Ranking
1st
2nd
3rd
4th
5th
Season
Jan/Feb
Seafood
salads, &
seafood &
vegetable
dishes,
17.6%
Shrimp,
11.2%
Seafood
cakes, fritters
& casseroles '
w/o
vegetables,
8.8%
Catfish, 8.3%
Fish
stick/fillet
7.8%
Mar/Apr
Seafood
salads, &
seafood &
vegetable
dishes,
16.9%
Shrimp,
10.5%
Tuna, canned,
10.1%
Seafood
cakes, fritters,
& casseroles
w/o
vegetables,
8.1%
Cod, 5.6%
May/Jun
Seafood
salads, &
seafood &
vegetable
dishes,
24.5%
Shrimp, 9.5%
Tuna, canned.
6.8%
Seafood
cakes, fritters,
& casseroles
w/o
vegetables,
6.4%
Fish
stick.fillet
5.5%
Jul/Aug
Seafood
salads, &
seafood &
vegetable
dishes,
23.2%
Seafood
cakes, fritters,
& casseroles
w/o
vegetables,
7.9%
Tuna, canned
7.5%
Salmon, 6.8%
Shrimp, 6.4%
Sep/Oct
Seafood
salads, &
seafood &
vegetable
dishes,
15.4%
Tuna, canned
12.0%
Shrimp,
11.5%
Seafood
cakes, fritters,
& casseroles
w/o
vegetables,
8.7%
Fish
stick/fillet,
6.7%
Nov/Dec
Seafood
salads, &
seafood &
vegetable
dishes,
20.0%
Shrimp,
11.1%
Seafood
cakes, fritters
& casseroles
w/o
vegetables,
10.0%
Fish
stick/fillet,
9.4%
Fish
stick/fillet,
9.4%
4-54
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Table 4-44 (continued)
Ten Most Commonly Reported Fish/Shellfish/Mixed Dishes by Season
CSFH 1994 and CSFII1995 Day 1 Data
Ranking
6th
7th
8th
9th
10th
Season
Jan/Feb
Tuna, canned,
6.3%
Salmon, 3
Trout, 2.4%
Shellfish
dishes in
sauce, 2.4%
Frozen
seafood
dinners. 2.4%
Mar/Apr
Salmon,
5.2%,
Fish,
unspecified,
4.8%
Seafood
sandwiches,
4.0%
Seafood
soups &
casseroles
with
vegetables.
3.6%
Porgy, 3.6%
May/Jun
Salmon, 4.5%
Seafood
sandwiches,
4.1%
Fish,
unspecified
3.6%
Sea bass,
3.2%
Trout.
2.7%
Jul/Aug
Fish
stick/fillet,
5.4%
Catfish,
4.6%
Cod,
4.6%
Ocean perch,
3.2%
Perch,
3.2%
Sep/Oct
Cod,
6.3%
Fish,
unspecified
4.8%
Flounder,
4.3%
Salmon,
3.4%
Catfish, 2.9%
Nov/Dec
Tuna, canned
7.8%
Salmon, 4.4%
Fish
unspecified,
4.4%
Haddock,
3.9%.
Frozen
seafood
dinners, 3.9%
Flounder,
3.3%
Communications with experts in the seafood industry as well as the import/export and productions
statistics published by the National Marine Fisheries Service and the Food and Agriculture Organization)
indicate the predominant species offish and shellfish are the various species of tuna, shrimp, and the
Alaskan pollock. Superimposed on these broad national trends in fish/shellfish consumption, are regional
trends in fish/shellfish consumption. Table 4-45 describes regional popularity offish species within the
United States.
4-55
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Table 4-45
Regional Popularity of Fish and Shellfish Species
Region
East Coast
South
West Coast
Mid-West
Most Popular Fish Consumed
haddock, cod*, flounder, lobster, blue crab,
shrimp
shrimp, catfish, grouper, red snapper, blue crab
salmon, dungeness crab, shrimp, rockfish
Perch, Walleye, Chubs, Multiple Varities of
Freshwater Fish
*In the late 1990s, cod has been replaced on menus largely by Alaskan pollock.
These impressions are supported by descriptions of the best-selling fish/shellfish species in various
types of restaurants as shown in Table 4-46 (Seafood Business magazine cited by Johnson, 1997, page 71).
Table 4-46
Popularity of Fish/Shellfish Species in Restaurants
Rank
First
Second
Third
By Region:
North East
South
Midwest
West/Pacific
Salmon
Shrimp
Salmon
Salmon
Shrimp
Salmon
Shrimp
Shrimp
Swordfish
Catfish
Cod*
Halibut
By Restaurant Style:
"Fast Food"
"Dinnerhouse"
"White Tablecloth"
Cod*/Shrimp
Shrimp
Salmon
Clams/Scallops
Salmon
Shrimp
Tuna
Lobster
Swordfish
By Overall Sales:
1996
1995
1994
1993
1992
Shrimp
Cod*
Cod*
Cod* (& All Whitefish)
Cod* (& All Whitefish)
Salmon
Shrimp/Salmon
Shrimp/Salmon
Shrimp
Shrimp
Cod*
Swordfish
Swordfish
Hoki
Crab
*ln the late 1990s, cod has been replaced on menus largely by Alaskan pollock.
4-56
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Although the species shown in Tables 4-45 and 4-46 are popular regionally, for the United Stales
as a whole, the national statistics indicate major fish consumed are: tuna, shrimp, and Alaskan pollock.
4.2.3.3 Fish and Shellfish Consumption by Children
The NHANES in data were analyzed to determine the species of fish and shellfish consumed by
children in the age categories l-to-5 years, 6-to-l 1 years, and 12-to-14 years for male and female survey
respondents. Specific choices by age groups are shown in Table 4-47. The top four fish dishes for all age
categories of children were:
fish sticks and patties,
tuna salad and canned tuna,
shrimp, and
catfish.
Table 4-47
Frequencies of Various Fish and Shellfish Food Types
for Children Ages 1 to 5 and 6 to 11 Years by Gender
(Source: NHANES III)
Food Type
Fish Sticks/Patties
Tuna Salad/
Canned Tuna
Shrimp
Catfish
AH Other fish and Shellfish
Total
Frequency of Various Food Types
Ages 1-5 Years
Females
23%
33%
8%
5%
31%
100%
Males
21%
27%
6%
5%
41%
100%
Ages 6-11
Females
23%
26%
11%
5%
35%
100%
Males
25%
19%
10%
10%
36%
100%
Ages 12-14
Females
21%
28%
12%
9%
30%
100%
Males
21%
25%
12%
4%
33%
100%
4.2.4 Production Patterns and Mercury' Concentrations for Specific Fish and Shellfish Species
Four species offish are important predictors of methylmercury exposure because of the frequency
with which these are consumed by the overall population.
4.2.4.1
Tuna
Although consumption of canned tuna continues to fall (Johnson, 1997), tuna (canned and fresh or
frozen) continues to be the most commonly consumed fish based on data from contemporary surveys of
food intake by individuals. The mercury concentration of tuna varies with species reflecting variability in
fish size and geographic location.
The mean mercury concentration in tuna is 0.206 |jg/gram based on data from NMFS. This
represents an average for the mean concentrations measured in three types of tuna: albacore tuna (0.264
4-57
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ug/g), skipjack tuna (0.136 ug/g, and yellowfin tuna (0.218 ug/g)- Data cited by U.S. FDA (1978) indicate
the following mean (maximum) values in ug/g for various tuna species: tuna, light skipjack, 0.144 (0.385);
tuna light yellow, 0.271 (0.870); tuna, white 0.350 (0.904). Cramer (1994) observed that recent U.S. FDA
surveys indicated that the mean mercury content of 1973 samples of canned tuna was 0.21 ug/g, whereas a
1990s survey of 245 samples of canned tuna was 0.17 ug/g mercury.
4.2.4.2 Shrimp
Shrimp consumption based on contemporary nationally representative surveys in the United States
continues to be a top-ten seafood choice by both adults and children. World shrimp supplies are in excess
of 3,000,000 metric tons (Johnson, 1997) with approximately one-sixth of the production grown by
aquaculture. This amounts to approximately 500,000 metric tons grown by aquaculture. The United
States is a net importer of shrimp with major suppliers (in order of the quantity imported into the United
States) Thailand, Ecuador, Mexico, and India (Johnson, 1997).
The overall averaged mercury concentration in marine shrimp reported by the NMFS is 0.047
ug/g. This is an average of the mean concentrations measured in seven types of shrimp: royal red shrimp
(0.074 ug/g), white shrimp (0.054 ug/g), brown shrimp; (0.048 ug/g), ocean shrimp (0.053 ug/g), pink
shrimp (0.031 ug/g), pink northern shrimp (0.024 ug/g), and Alaska (sidestripe) shrimp (0.042 ug/g).
Data cited by U.S. FDA (1978) indicate a mean value of 0.040 with a maximum of 0.440 ug/g.
Shrimp consumed in the United States are predominantly imported from Thailand, Ecuador, and
India. The authors of the Report to Congress have not identified data specifically reporting mercury
concentrations in shrimp from the countries which are currently the major suppliers of shrimp to the United
States.
4.2.4.3 Pollock
The Alaskan pollock dominates the U.S. seafood industry. In 1996, pollock landings totaled 2.6
billion pounds (Johnson, 1997). Pollock is the fish species used in preparation offish sticks, fish
sandwiches served by various "fast food" restaurant franchises in the United States, artificial "crab" or
surimi.
The mercury concentration attributed to pollock is 0.15 ug/g based on NMFS data. Data cited by
U.S. FDA indicate a mean mercury concentration for pollock of 0.141 (maximum value, 0.96 ug/g).
4.2.4.4 Salmon
Salmon is a highly important fish species based on frequency of consumption of both the canned
and fresh product. Species include: chinook, coho, chum, sockeye, and pink. Production has declined in
the United States between 1995 and 1996, although the world supply of salmon has continued to grow.
Salmon is one of the major fish species grown by aquaculture with production of approximately 50 million
pounds per year in the United States.
The mercury content used for salmon was the average of the mean concentrations measured in five
types of salmon: pink (0.019 ug/g), chum (0.030 ug/g), coho (0.038 ug/g), sockeye (0.027 ug/g), and
chinook (0.063 ug/g). Salmon that is raised by aquaculture based on consumption of com and soy
products may have lower mercury concentrations because of the low mercury concentration of the
vegetable products fed to the aquaculture-raised salmon. Data cited by U.S. FDA (1978) indicated a mean
value for salmon of 0.040 (maximum 0.201).
4-58
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4.2.4.5 Catfish
Catfish ranks in the top ten fish produced and consumed. Catfish dominates the aquacufture
production in the United States with production of approximately 475 million pounds round (i.e., live)
weight. The mercury concentration of freshwater catfish used in the Mercury Study Report to Congress
was 0.088 jig/g. Data cited by U.S. FDA (1978) indicate a mean value of 0.146 ug/g (with a maximum
value of 0.38 ug/g). As with salmon, catfish raised by aquaculture on vegetable products (e.g., corn and
soy) are predicted to have lower mercury concentrations than capture catfish.
4.3 Mercury Concentrations In Fish
Mercury concentrations in marine, estuarine, and freshwater fish were obtained from data bases
maintained for marine and estuarine fish and shellfish (National Marine Fisheries Service, 1978) and
freshwater fish (Lowe et al., 1985; and Bahnick et al., 1994). These data combined with estimates of
fish/shellfish consumption from various dietary surveys form the basis for predicted mercury exposures
through fish and shellfish.
4.3.1 National Marine Fisheries Service Data Base
Analyses of total mercury concentrations in marine and estuarine fish and shellfish have been
carried out over the past two to three decades. Data describing methylmercury concentrations in marine
fish were predominantly based on the National Marine Fisheries' Service (NMFS) data base, the largest
publicly available data base on mercury concentrations in marine fish. In the early 1970s, the NMFS
conducted testing for total mercury on over 200 seafood species of commercial and recreational interest
(Hall et al., 1978). The determination of mercury in fish was based on flameless (cold vapor) atomic
absorption spectrophotometry following chemical digestion of the fish sample. These methods were
described in Hall et al. (1978).
Although the NMFS data were initially compiled beginning in the 1970s, comparisons of the
mercury concentration identified in the NMFS's data base with compliance samples obtained by the U..S-.
FDA indicate that the NMFS data are appropriate to use in estimating intake of mercury from fish at the
national level of data aggregation. Cramer (1994) of the Office of Seafood of the Center for Food Safety
and Applied Nutrition of the U.S. FDA reported on Exposure of U.S. Consumers to Methylmercury from
Fish. He noted that recent information from NMFS indicated that the fish mercury concentrations reported
in the 1978 report do not appear to have changed significantly. The U.S. FDA continues to monitor
methylmercury concentration in seafood. Cramer (1994) observed that results of recent U.S. FDA surveys
indicate results parallel to earlier findings by U.S. FDA and NMFS. To illustrate, Cramer estimated the
mean methylmercury content of the 1973 samples of canned tuna at 0.21 ug/g mercury, whereas a recently
completed survey of 245 samples of canned tuna was 0.17 ug/g mercury. These data are considered to be
comparable, although the small decrease reported between these two studies may reflect increased use in:
canned tuna of tuna species with slightly lower average methylmercury concentrations. The National
Academy of Sciences' National Research Council's Subcommittee on Seafood Safety (1991) also assessed
the applicability of the NMFS' 1970s data base to current estimates of mercury concentrations in fish.. This
subcommittee also concluded that the 1978 data base differed little in mercury concentrations from ILS.
FDA compliance samples estimating mercury concentrations in fish.
Assessment of this data base by persons with expertise in analytical chemistry and patterns of
mercury contamination of the environment have indicated that temporal patterns in mercury concentrations
in fish do not preclude use of this data base in the present risk assessment (US EPA's Science Advisory
Board's ad hoc Mercury Subcommittee; Interagency Peer Review Group, External Peer Review GroupX
4-59
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One issue that did arise, however, concerned how zero and trace values were entered into calculation of
mean mercury concentrations. This has been evaluated statistically through comparison of mean values
when different approaches were taken to mathematically calculated means under different assumptions of
inclusion of zero and trace values.
The NMFS Report provided data on number of samples, number of nondetects, and mean,
standard deviation, minimum and maximum mercury levels (in parts per million wet weight) for 1,333
combinations offish/shellfish species, variety, location caught, and tissue (Hall et al., 1978). This data
base includes 777 fish/shellfish species for which mercury concentration data are provided. This
represents 5,707 analyses of fish and shellfish tissues for total mercury, of which 1,467 or 26%, are
reported as nondetectable levels. Because the mercury concentration data are used in our analyses at the
species level, not at the more detailed species/variety/location/tissue level, the data have been grouped to
reflect 35 different fish/shellfish species.
The frequency of nondetectable or "zero" values differs with the mercury concentration. When
mean mercury levels are relatively "large", there are few, if any, nondetects, so the methodology employed
to handle nondetects is irrelevant. When mean mercury levels are small, there are relatively large numbers
of nondetectable values. Because the method of including/excluding nondetectable values in the
calculation has the greatest impact only when mercury concentrations are very low, the overall impact on
estimated mercury exposure is small.
A statistical assessment of these potential differences was carried out by Westat Corporation
(Memo from Robert Clickner, September 26, 1997). A description of the statistical basis for the
comparison is shown in Appendix C. To determine the detection limit applicable to the data base, the
lowest of all detected analytical values was presumed to be the detection limit. This value is 0.010 pg/g
wet weight. The major conclusion of this analysis is that different methods of handling nondetects have
negligible impact on the reported mean concentrations. Consequently the mean values as reported by the
NMFS will be used in preparing estimates of mercury intake from marine and estuarine fish and shellfish.
Mercury concentration in various fish species are shown in Table 4-48.
Table 4-48
Summary of Mercury Concentrations in Fish Species
(Hg Hg/g fresh weight)
Data Used by USEPA
Mercury Study Report to
Congress*
1997
Fish Species
Abalone
Anchovies
Average
(Mg Hg/g)
0.016
0.047
Data Used by US FDA
Report on the Chance of U.S.
Seafood Consumers Exceeding "The Current
Daily Intake for Mercury and Recommended
Regulatory Controls"
1978
Fish Species
Abalone
Anchovies
Average
0*&Hg/g)
0.018
0.039
Maximum
Cue Hg/g)
0.120
0.210
Data Used by Stern et al.
1996
Fish
Species
Not
Reported
(NR)
NR
Average
(A*E Hs/g)
4-60
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Table 4-48 (continued)
Summary of Mercury Concentrations in Fish Species
(fig Hg/g fresh weight)
Data Used by USEPA
Mercury Study Report to
Congress*
1997
Fish Species
Bass,
Freshwater
Bass, Sea
Bluefish
Bluegills
Bonito
Bonito
Butterfish
Carp,
Common
Catfish
(channel.large
mouth, rock,
stnped. white)
Catfish
(Marine)
Clams
Cod
Crab, King
Crab
Average
(v* Hg/g)
Avgs.= 0.157
(Lowe et al.,
1985) and
0.38 (Bahnick
etal., 1994)
Not Reported
Not Reported
0.033
Not Reported
Not Reported
Not Reported
0.093
0.088
Not Reported
0.023
0121
0.070;
Calculations
based on 5
species of crab
combined at
0.117
0.117
Data Used by US FDA
Report on the Chance of U.S.
Seafood Consumers Exceeding "The Current
Daily Intake for Mercury and Recommended
Regulatory Controls"
1978
Fish Species
Bass,
Striped
Bass. Sea
Bluefish
Bluegills
Bonito
(below
3197)
Bonito
(above
3197)
Butterfish
Carp
Catfish
(freshwater)
Catfish
(Marine)
Clams
Cod
Crab, King
Crab, other
than Kine
Average
(MS Hg/g)
0.752
0.157
0.370
0.259
0.302
0.382
0.021
0.181
0.146
0.475
0.049
0.125
0.070
0.140
Maximum
(MS Hg/g)
2.000
0.575
1.255
1.010
0.470
0.740
0190
0.540
0380
1.200
0.260
0.590
0.240
0.610
Data Used by Stern etaL
19%
Fish
Species
Bass,
freshwater
Bass, Sea
Bluefish
NR
NR
NR
Butterfish
Catfish,
freshwater
Clams
Cod/Scrod
See crab.
Crab
NR
NR
Average
G/gHg/R)
0.41
0.25
0.35
0.05
0.15
0.05
0.15
0.15
4-61
-------
Table 4-48 (continued)
Summary of Mercury Concentrations in Fish Species
(ug Hg/g fresh weight)
Data Used by USEPA
Mercury Study Report to
Congress*
1997
Fish Species
Crappie
(black, white)
Croaker
Dolphin
Drums,
Freshwater
Flounders
Groupers
Haddock
Hake
Halibut
Halibut
Halibut
Halibut
Hemng
Kingfish
Lobster
Lobster
Lobster
Spiny
Mackerel
Average
(UK Hs/e)
0.114
0.125
Not Reported
0.117
0.092
0.089
0.145
0.250
0.250
0.250
0.250
0.013
0.100
0.232
0.232
0.232;
Includes spiny
(Pacific)
lobster=0.210
0.081;
Averaged
Chub = 0.081;
Atlantic=
0.025;
Jack=0.138
Data Used by US FDA
Report on the Chance of U.S.
Seafood Consumers Exceeding "The Current
Daily Intake for Mercury and Recommended
Regulatory Controls"
1978
Fish Species
Crappie
Croaker
Dolphin
Drums
Flounders
Groupers
Haddock
Hake
Halibut 4
Halibut 3
Halibut 2H
Halibut 25
Hemng
Kingfish
Lobster,
Northern 1 1
Lobster
Northern 10
Lobster.Spin
y
Mackerel,
Atlantic
Average
(us Hg/g)
0.262
0.124
0.144
0.150
0.096
0.595
0.109
0.100
0187
0.284
0.440
0534
0.023
0.078
0.339
0.509
0.113
0.048
Maximum
0*8 Hg/g)
1.390
0.810
0.530
0.800
0.880
2.450
0.368
1.100
1.000
1.260
1.460
1.430
0.260
0.330
1.603
2.310
0.370
0.190
Data Used by Stern et al.
1996
Fish
Species
NR
NR
Dolphin
(Mahi-
mahi)
NR
Flounder
NR
Haddock
Hake
Halibut
Halibut
Halibut
Halibut
Hemng
Kingfish
Lobster
Lobster
Lobster
Mackerel
Average
Oig Hg/g)
0.25
0.10
0.05
0.10
0.25
0.25
0.25
0.25
005
0.05
0.25
0.25
0.25
0.28
4-62
-------
Table 4-48 (continued)
Summary of Mercury Concentrations in Fish Species
(fig Hg/g fresh weight)
Data Used by USEPA
Mercury Study Report to
Congress*
1997
Fish Species
Mackerel
Mackerel
Mackerel
Mackerel
Mackerel
Mullet
Oysters
Perch.
White and
Yellow
Perch,
Ocean
Pike.
Northern
Pollock
Pompano
Rockfish
Sablefish
Salmon
Scallops
Scup
Sharks
Shrimp
Smelt
Average
(UK Hg/g)
0.081
0.081
0.081
0.081
0.081
0.009
0.023
0 110
0 116
0.310
0 127
0.150
0.104
Not Reported
Not Reported
0.035
0.042
Not Reported
1.327
0.047
0 100
Data Used by US FDA
Report on the Chance of U.S.
Seafood Consumers Exceeding "The Current
Daily Intake for Mercury and Recommended
Regulatory Controls"
1978
Fish Species
Mackerel,
Jack
Mackerel,
King (Gulf)
Mackerel,
King (other)
Mackerel.
Spanish 16
Mackerel,
Spanish 10
Mullet
Oysters
Perch,
Freshwater
Perch.
Marine
Pike
Pollock
Pompano
Rockfish
Sablefish
Salmon
Scallops
Scup
Sharks
Shrimp
Smelt
Average
C"g Hg/g)
0.267
0.823
1.128
0.542
0.825
0.016
0.027
0.290
0.133
0.810
0.141
0.104
0.340
0.201
0.040
0.058
0.106
1.244
0040
0.016
Maximum
(//gHg/g)
0.510
2.730
2.900
2.470
1.605
0.280
0.460
0.880
0.590
1.710
0.960
8.420
0.930
0.700
0.210
0.220
0.520
4.528
0.440
0.058
Data Used by Stern etal.
1996
Fish
Species
Mackerel
Mackerel
Mackerel
Mackerel
Mackerel
Mullet
NR
Perch
NR
NR
NR
NR
NR
NR
Salmon
NR
NR
Shark
Shrimp
Smelts
Average
(MgHg/g)
0.28
0.28
0.28
0.28
0.28
0.05
0.18
0.05
1.11
0.11
0.05
4-63
-------
Table 4-48 (continued)
Summary of Mercury Concentrations in Fish Species
(ug Hg/g fresh weight)
Data Used by USEPA
Mercury Study Report to
Congress*
1997
Fish Species
Snapper
Snapper
Snook
Spot
Squid
Octopi
Sunfish
Swordfish
Tillefish
Trout,
Trout
Tuna
Tuna
Tuna
Whitefish
Other finfish
Average
(ME Hg/g)
0.25
0.25
Not Reported
Not Reported
0.026
0.029
Not Reported
0.95
Not Reported
0.149
0.149
0.206;
Averaged:
Tuna, light
skipjack=0.13
6Tuna,light
yellow=0.218;
Albacore=0.2
64
0.206
0.206
Not Reported
Data Used by US FDA
Report on the Chance of U.S.
Seafood Consumers Exceeding "The Current
Daily Intake for Mercury and Recommended
Regulatory Controls"
1978
Fish Species
Snapper.Red
Snapper,
Other
Snook
Spot
Squid and
Octopi
Squid and
Octopi
Sunfish
Swordfish
Tillefish
Trout,
Freshwater
Trout,
Marine
Tuna,
Light
Skipjack
Tuna,
Light
Yellow
Tuna, White
Whitefish
Other finfish
Average
(MZ Hg/g)
0.454
0.362
0.701
0.041
0.031
0.031
0.312
1.218
1.607
0.417
0.212
0.144
0.271
0.350
0.054
0.287
Maximum
C"gHg/g)
2.170
1.840
1.640
0.180
0.400
0.400
1.200
2.720
3.730
1.220
1.190
0.385
0.870
0.904
0.230
1.020
Data Used by Stern etal.
1996
Fish
Species
Snapper
Snapper
NR
Spotfish
Squid
NR
NR
Swordfish
NR
Trout
Trout
Tuna,
fresh
Tuna,
fresh
Tuna,
fresh
Whitefish
Finfish,
other
Average
(M HS/E)
0.31
0.31
0.05
0.05
0.93
0.05
0.05
0.17
0.17
0.17
004
0.17
4-64
-------
Table 4-48 (continued)
Summary of Mercury Concentrations in Fish Species
(ug Hg/g fresh weight)
Data Used by USEPA
Mercury Study Report to
Congress*
1997
Fish Species
Other shellfish
Average
G^g Hg/g)
Not
Reported
Data Used by US FDA
Report on the Chance of U.S.
Seafood Consumers Exceeding "The Current
Daily Intake for Mercury and Recommended
Regulatory Controls"
1978
Fish Species
Average
(MR Hg/g)
Maximum
teE Hg/g)
Data Used by Stern etaL
1996
Fish
Species
Shellfish,
other
Average
teg Hg/g)
0.12
Fish Species (Freshwater) Not Reported by FDA, 1978
Bloater
Smallmouth
Buffalo
Northern
Squawfish
Sauger
Sucker
Walleye
Trout (brown,
lake, rainbow)
0.0.93
0.096
0.33
0.23
0.1 14 (Lowe
etal., 1985,
0.167
(Bahnick et
al., 1994).
0.1 00 (Lowe
etal., 1985)
and 0.52
(Bahnick et
al.. 1994)
0.149 (Lowe
etal., 1985)
and 0.1 4
(Bahnick et
al., 1994 for
brown trout).
Fish Species Reported by the State of New Jersey
and Not Reported by EPA or FDA
Blowfish
Orange roughy
Sole
Weak fish
Porgy
Blacklist!
0.05
0.5
0.12
0.15
0.55
0.25
4-65
-------
Table 4-48 (continued)
Summary of Mercury Concentrations in Fish Species
(ug Hg/g fresh weight)
Data Used by USEPA
Mercury Study Report to
Congress*
1997
Fish Species
Whiting
Turbot
Sardines
Tilapia
Average
(MS Hg/g)
Data Used by US FDA
Report on the Chance of U.S.
Seafood Consumers Exceeding "The Current
Daily Intake for Mercury and Recommended
Regulatory Controls"
1978
Fish Species
Average
J^g Hg/g)
Maximum
(MK Hg/g)
Data Used by Stern et al.
1996
Fish
Species
Average
(UK He/s)
0.05
0.10
0.05
0.05
* See Sections 4.3.1 and 4.3.2 for data on marine species, and Section 4.3.3 for data on freshwater fish.
4.3.2 Mercury Concentrations in Marine Fish
Data supplied by NMFS give the mercury concentrations in fresh weight of fish muscle of
numerous marine fish, shellfish, and other molluscan/crustacean species shown in Table 4-49, 4-50 and
4-51.
Table 4-49
Mercury Concentrations in Marine Finfish
Fish
Anchovy1
Barracuda, Pacific2
Cod3
Croaker, Atlantic
Eel, American
Flounder4
Haddock
Hake5
Halibut6
Herring7
Kingfish8
Mercury Concentration
(^ig/g, wet weight)
0.047
0.177
0.121
0.125
0.213
0.092
0.089
0.145
0.25
0.013
0.10
Source of Data
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
4-66
-------
Table 4-49 (continued)
Mercury Concentrations in Marine Finfish
Fish
Mackerel9
Mullet10
Ocean Perch11
Pollack
Pompano
Porgy
Ray
Salmon12
Sardines13
Sea Bass
Shark14
Skate15
Smelt, Rainbow
Snapper16
Sturgeon17
Swordfish
Tuna18
Whiting (silver hake)
Mercury Concentration
(/^g/g, wet weight)
0.081
0.009
0.116
0.15
0.104
0.522
0.176
0.035
0.1
0.135
1.327
0.176
0.1
0.25
0.235
0.95
0.206
0.041
Source of Data
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
NMFS
FDA Compliance Testing
NMFS
NMFS
1 This is the average of NMFS mean mercury concentrations for both striped anchovy (0.082 ug/g) and northern anchovy (0.010
Kg/g)
2 USDA data base specified the consumption of the Pacific barracuda and not the Atlantic barracuda.
3 The mercury content for cod is the average of the mean concentrations in Atlantic cod (0.114 ^g/g and the Pacific cod (0.127
ug/g)
4 The mercury content for flounder is the a\erage of the mean concentrations measured in 9 types of flounder: Gulf (0.147 ^g/g),
summer (0.127 ,ug/g), southern (0.078 ,ug/g), four-spot (0.090 ,ug/g), windowpane (0.151 ^g/g), arrowtooth (0.020 /ug/g), witch
(0.083 A
-------
12 The mercury content for salmon is the average of the mean concentrations measured in 5 types of salmon: pink (0.019 Mg/g),
chum (0.030 ^g/g), coho (0.038 Mg/g), sockeye (0.027 ^g/g), and Chinook (0.063 ^g/g).
13 Sardines were estimated from mercury concentrations in small Atlantic herring.
14 The mercury content for shark is the average of the mean concentrations measured in 9 types of shark: spiny dogfish (0.607
Aig/g), (unclassified) dogfish (0.477 A
-------
Table 4-51
Mercury Concentrations in Marine Molluscan Cephalopods
Cephalopod
Octopus
Squid'
Mercury Concentration
(/^g/g wet wt.)
0.029
0.026
Source of Data
NMFS
NMFS
1 The mercury content for squid is the average of the mean concentrations measured in 3 types of squid: Atlantic
longfinned squid (0.025 jug/g), short-finned squid (0.034 Mg/g), and Pacific squid (0.018 ^g/g)
4.3.3 Freshwater Fish Mercury Data Base
Freshwater fish mercury concentrations were reported by Lowe et al. (1985) and by Bahnick et al.
(1994). Details of their analyses are presented separately from those on marine fish. Lowe et al. (1985)
used flameless cold vapor technique absorption spectrophotometry in their analyses. Mean recovery for
mercury averaged 96.6±14.4 (SD) based on 72 analyses of spiked samples. Duplicate analyses showed a
percent difference of 10.6+14.4 (SD) based on 51 duplicates. Values were reported as the geometric
means, minimum, and maximum of elemental mercury concentrations during 1978 to 1979 and during
1980 to 1981. The limit of detection for mercury was 0.01 ug/g wet weight. Standard reference materials
were included and resulted of their analysis are shown in Table 4-52.
Table 4-52
Analyses of Mercury Standard Reference Materials Used by Lowe et al. (1985)
in Support of Analyses of Freshwater Fish
Mercury Reference
Material
bovine liver
oyster
tuna
Certified
Concentration Range
(Mg/g)
0.016±0.002
0.057+0.015
0.95+0.10
Number of Samples
Analyzed
53
14
32
Measured
Concentrations (Mg/g:
mean + 1SD)
0.021+0.007
0.050+0.005
0.86+0.07
Values of 0.01 ug mercury/g fish tissue are routinely reported in this data base. Samples were
handled as individual fish. Mercury residues were reported for all species and all locations. The geometric
mean mercury concentrations for all freshwater fish species was 0.11 ug/g in 1978 to 1979 and 0.11 ug/g
in 1980-1981. The minimum value for both time periods was 0.01 ng/g and the maximum value was 1,10
ug/g in 1978-1979 and 0.77 ug/g in 1980-1981. The 85th percentile value in both time periods was 0.18
Mg/g-
Bahnick et al. (1994) used cold mercury vapor flameless atomic absorption and detected mercury
in 92.2% of the fish sampled. Non-detects were reported as a zero value and averaged as zeros. Two
separate detection limits were reported. Prior to 1990, 465 samples were analyzed using a method having
4-69
-------
a detection limit of 0.05 ug/g. Modification of the method for the final 195 samples produced a detection
limit of 0.0013 ug/g. The estimated standard deviation for replicate samples was 0.047 ug/g in the
concentration range of 0.08 to 1.79 ug/g. Analysis of EPA reference fish having a reported experimental
mean value of 2.52 ug/g (s=0.64) produced a mean value for mercury of 2.87 (s=0.08) in this study. The
mean value for the overall data set for 669 samples was 0.26 ug/g. Mercury was detected in fish collected
from the 374 sites.
Because mercury emissions from the ambient sources considered in the current Report to Congress
have different impacts on global and local deposition, it was considered important to separate fish species
by habitat. Specifically, global mercury cycling was judged to have its greatest impact on marine species,
whereas local deposition was considered more likely to affect estuarine and freshwater fish and shellfish
species. The species were classified as shown in Table 4-14 on a classification system described by Jacobs
et al. (in press).
Central tendency estimates of seafood mercury concentrations were utilized in the report. This
seems appropriate since commercial seafood is widely distributed across the United States (Seafood Safety,
1991). The source of a particular fish purchase is generally not noted by the consumer (e.g., canned tuna).
As a result, a randomness and averaging may be achieved. Additionally, only common names of
commercial seafood were utilized; specific species which could be considered to be that type of fish were
included in the central tendency estimate. Again, typical consumers were assumed to generally not be
aware of the species offish they were consuming, rather just the type.
As noted above, there are other estimates of mercury concentrations in seafood. After the analysis
of mercury exposure from seafood was completed for this Report, two other databases were obtained: U.S.
FDA and Stern et al. (1996). These data are presented in Table 4-51 for comparison with those data used
for this analysis.
4.3.4 Mercury Concentrations In Freshwater Fish
Estimation of average mercury concentrations in freshwater finfish from across the United States
required a compilation of measurements of fish mercury concentrations from randomly selected U.S. water
bodies. A large number of sources of mercury concentrations in fish were not used in this part of the
assessment. Mercury concentrations in fish have been analyzed for a number of years in many local or
regional water bodies in the United States; several of these studies are detailed in this Report. Data
described in this body of literature are a collection of individual studies which characterize mercury
concentrations in fish from specific geographic regions such as individual water bodies or in individual
states. Many of the studies were initiated because of a problem, perceived or otherwise, with mercury
concentrations in the fish or the water body. Thus, the sample presented by a compilation of these data
may be biased toward the high-end of the distribution of mercury concentrations in freshwater fish.
Additionally, the methods varied from study to study, and there is no way of determining the consistency
of the reported data from study to study.
Two studies, more national in scope, are thought to provide a more complete picture of mercury
concentrations in U.S. freshwater finfish populations: "National Contaminant Biomonitoring Program:
Concentrations of Seven Elements in Freshwater Fish, 1978-1981" by Lowe et al. (1985) and "A National
Study of Chemical Residues in Fish" conducted by U.S. EPA (1992) and also reported in Bahnick et al.
(1994).
Lowe et al. (1985) reported mercury concentrations in fish from the National Contaminant
Biomonitoring Program. The freshwater fish data were collected between 1978-1981 at 112 stations
4-70
-------
located across the United States. Mercury was measured by a flameless cold vapor technique, and the
detection limit was 0.01 ug/g wet weight. Most of the sampled fish were taken from rivers (93 of the 112
sample sites were rivers); the other 19 sites included larger lakes, canals, and streams. Fish weights and
lengths were consistently recorded. A wide variety of types of fishes were sampled: most commonly carp,
large mouth bass and white sucker. The geometric mean mercury concentration of all sampled fish was
0.11 ug/g wet weight; the minimum and maximum concentrations reported were 0.01 and 0.77 ug/g wet
weight, respectively. The highest reported mercury concentrations (0.77 ug/g wet weight) occurred in the
northern squawfish of the Columbia River. See Table 4-53 for mean mercury concentrations by fish
species.
Table 4-53
Freshwater Fish Mercury Concentrations from Lowe et ai., (1985)
Species
Bass
Bloater
Bluegill
Smallmouth Buffalo
Carp, Common
Catfish (channel, largemouth. rock, striped, white)
Crappie (black, white)
Fresh-water Drum
Northern Squawfish
Northern Pike
Perch (white and yellow)
Sauger
Sucker (bridgelip. carpsucker, klamath, largescale, longnose,
rivercarpsucker. tahoe)
Trout (brown, lake, rainbow)
Walleye
Mean of all measured fish
Mean Mercury Concentration fig/g
(fresh weight)
0.157
0.093
0.033
0.096
0.093
0.088
0.114
0.117
0.33
0.127
0.11
0.23
0.114
0.149
0.100
0.11
"A National Study of Chemical Residues in Fish" was conducted by U.S. EPA (1992) and also
reported by Bahnick et al. (1994). In this study mercury concentrations in fish tissue were analyzed. Five
bottom feeders (e.g., carp) and five game fish (e.g., bass) were sampled at each of the 314 sampling sites in
the United States. The sites were selected based on proximity to either point or non-point pollution
sources. Thirty-five "remote" sites among the 314 were included to provide background pollutant
concentrations. The study primarily targeted sites that were expected to be impacted by increased dioxin
levels. The point sources proximate to sites of fish collection included the following: pulp and paper
4-71
-------
mills, Superfund sites, publicly owned treatment works and other industrial sites. Data describing fish age,
weight, and sex were not consistently collected. Whole body mercury concentrations were determined for
bottom feeders and mercury concentrations in fillets were analyzed for the game fish. Total mercury levels
were analyzed using flameless atomic absorption; the reported detection limits were 0.05 ug/g early in the
study and 0.0013 ug/g as analytical technique improved later in the analysis. Mercury was detected in fish
at 92% of the sample sites. The maximum mercury level detected was 1.8 ug/g, and the mean across all
fish and all sites was 0.26 ug/g. The highest measurements occurred in walleye, large mouth bass and
carp. The mercury concentrations in fish around publicly owned treatment works were highest of all point
source data; the median value measured were 0.61 ug/g. Paper mills were located near many of the sites
where mercury-laden fish was detected. Table 4-54 contains the mean mercury concentrations of the
species collected by Bahnick et al. (1994).
Both the studies reported by Lowe et al. (1985) and by Bahnick et al. (1994) appear to be
systematic, national collections of fish pollutant concentration data. Clearly, higher mercury
concentrations in fish have been detected in other analyses, and the values obtained in these studies should
be interpreted as a rough approximation of the mean concentrations in freshwater finfishes. As indicated
in the range of data presented in Tables 4-53 and 4-54, as well as the aforementioned Tables in Chapter 2,
wide variations are expected in data on mercury concentrations in freshwater fish.
The mean mercury concentrations in all fish sampled vary by a factor of two between the studies.
The mean mercury concentration reported by Lowe et al.(1985) was 0.11 ug/g, whereas the mean mercury
concentration reported by Bahnick et al. (1994) was 0.26 ug/g. This difference can be extended to the
highest reported mean concentrations in fish species. Note that the average mercury concentrations in bass
and walleye reported by Bahnick's data are higher than the northern squawfish, which is the species with
the highest mean concentration of mercury identified by Lowe et al. (1985).
The bases for these differences in methylmercury concentrations are not immediately obvious.
The trophic positions of the species sampled, the sizes of the fish, or ages of fish sampled could
significantly increase or decrease the reported mean mercury concentration. Older and larger fish, which
occupy higher trophic positions in the aquatic food chain, would, all other factors being equal, be expected
to have higher mercury concentrations. The sources of the fish also influence fish mercury concentrations.
Most of the fish obtained by Lowe et al. (1985) were from rivers. The fate and transport of mercury in
river systems is less well characterized than in small lakes. Most of the data collected by Bahnick et al.
(1994) we:, collected with a bias toward more contaminated/industrialized sites, although not sites
specifically contaminated with mercury. It could be that there is more mercury available to the aquatic
food chains at the sites reported by Bahnick et al. (1994). Finally, the increase in the more recent data as
reported in Bahnick et al. (1994) could be the result of temporal increases in mercury concentrations.
There is a degree of uncertainty in the mercury concentrations selected for this assessment. This
uncertainty reflects both the adequacy of the sampling protocol for this application and the known
variability in fish body burden. The variability in these data is as broad as the range of reported
concentrations, which extends from non-detect (below 0.01 ug/g wet weight) up to 9 ug/g wet weight.
Where possible, when specific freshwater fish species are described in the USDA 3-day consumption
studies, the mean methylmercury concentration for that particular species was derived in two separate
calculations based on the data on methylmercury concentration in the fish reported by Lowe et al. (1985)
and by Bahnick et al. (1994).
Data for mean mercury concentration in freshwater fish from Bahnick et al. (1994) were combined
with the U.S. consumption rates for freshwater fish from the CSFII 89-91, CSFH 1994, CSFH 1995, and
NHANES HI to estimate methylmercury intakes for the population. The concentrations in the fish utilized
4-72
-------
are shown in Table 4-54. The exposure estimates for freshwater fin fish consumption are found in Table
4-55. Bahnick et al. (1994) freshwater fish concentration data were utilized, along with data on mercury
concentrations in marine fish and shellfish (Tables 4-48, 4-49,4-50) to calculate total exposure, for general
U.S. population, to mercury through consumption offish and shellfish (shown in Table 4-55).
Some species of freshwater fishes were not sampled by Bahnick et al. (1994), and some
respondents in the USDA CSFII 89-91 survey did not identify the type of freshwater fish consumed. In
these situations, it was assumed that the fish consumed contained 0.26 ng methylmercury/g, which
is the average of all sampled fish Bahnick et al. (1994). It is important to note that the freshwater fish data
are for wild populations not farm-raised fish.
Table 4-54
Mercury Concentrations in Freshwater Fish
U.S. EPA (1992) and Bahnick et al. (1994)
Freshwater Fish
Carp
Sucker1
Catfish, Channel and Flathead
Bass:
Walleye
Northern Pike
Crappie
Brown Trout
Mean All Fish Sampled
Average Mercury Concentration (/ug/g, wet weight)
0.11
0.167
0.16
0.38
0.52
0.31
0.22
0.14
0.26
1 The value presented is the mean of the average concentrations found in three types of sucker fish (white, redhorse and spotter).
: The value presented is the mean of the average concentrations found in three types of bass (white, largemouth and smallmouth).
4.3.5 Calculation of Mercury Concentrations in Fish Dishes
To estimate the mercury intake from fish and fish dishes reported as consumed by respondents in
the CSFII surveys and NHANES IE survey, several steps were taken. Using the Recipe File available
from USDA, the fish species for a particular reported food was identified. The average mercury
concentration in fish tissue on a fresh (or wet) weight basis was identified using the NMFS data or the data
reported by Bahnick et al. (1994). The food intake of the U.S. population includes a large number of
components of aquatic origin. A few of these appear not to have been analyzed for mercury
concentrations. Methylmercury concentration data were not available for some infrequently consumed
food items; e.g., turtle, roe or jelly fish. Data on the quantity of fish present in commercially prepared
soups were also not available and were excluded from the analysis.
Physical changes occur to a food when it is processed and/or cooked. The NMFS and Bahnick et
al. (1994) data bases were used to estimate mercury intake report mercury concentrations on a /ug mercury
4-73
-------
per gram of fresh tissue basis. Earlier research (Bloom, 1992) indicated that over 90% of mercury present
in fish and shellfish is chemically speciated as methylmercury which is bound to protein in fish tissue.
Morgan et al. (1994) indicated that over 90% of mercury present in fish and shellfish is chemically
speciated as methylmercury. Consequently the quantity of methylmercury present in the fish tissue in the
raw state will remain in the cooked or processed fish. In cooking or processing raw fish, there is typically a
reduction in the percent moisture in the food. Thus, mercury concentration data were recalculated to
reflect the loss of moisture during food processing, as well as retention of methylmercury in the remaining
lowered-moisture content fish tissues. Standard estimates of cooking/processing-related weight reductions
were provided by Dr. Betty Perloff and Dr. Jacob Exler, experts in the USDA recipe file and in USDA's
food composition. Percent moisture lost for baked or broiled fish was 25%. Fried fish products lose
weight through loss of moisture but add weight from fat added during frying for a total weight loss of
minus 12%. The percent moisture in fish that were dried, pickled or smoked was identified for individual
fish species (e.g., herring, cod, trout, etc.) from USDA handbooks of food composition. Information on
the percent moisture in the raw, and in the dried, smoked or pickled fish was obtained. The methylmercury
concentration in the fish was recalculated to reflect the increased methylmercury concentration of the fish
as the percent moisture decreased in the drying, pickling or smoking process.
The mean mercury concentrations for all fish from Lowe et al. (1985) and Bahnick et al. (1994)
were combined with the freshwater fish consumption data to estimate a range of exposure from total fish
consumption. Given the human fish consumption rates and the differences between the mercury
concentrations in the two data sets, it is important to use data from both studies of mercury exposures to
assess mean concentrations in fish. For purposes of comparison both sets of data were utilized to illustrate
the predicted methylmercury exposure. For this comparison, the average mercury concentrations for fish
in the Lowe and the Bahnick data were analyzed separately by combining the freshwater fish data with the
data in Tables 4-48 through 4-50. The bodyweight data and the freshwater fish consumption rates were
obtained from Table 4-12. Exposure to methylmercury based on an assumption of 0.11 ug
methylmercury/g fish tissue (wet weight) (Lowe et al., 1985). These values are estimated on a body weight
basis. Tables 4-53 and 4-54 were developed using the mean data on mercury concentrations for all fishes
sampled for these two studies.
Human mercury intake from fish was estimated by combining data on mercury concentration in
fish species with the reported quantities and types offish species reported as consumed by "users" in the
national food consumption surveys. The mercury concentrations in the consumed fish reported by the
national surveys were estimated using data on mercury concentration in fish expressed as micrograms of
mercury per gram fresh-weight of fish tissue.
The CSFII 89-91, CSFII 1994, and CSFII 1995 are three of the USDA's food consumption
surveys. An additional nationally-based food consumption survey is the third National Health and
Nutrition Examination Survey. The food items reported by individuals interviewed in these surveys are
identified by 7-digit food codes. The USDA has developed a recipe file identifying the primary
components that make up the food or dish reported "as Eaten" by a survey respondent. The total weight of
a fish-containing food is typically not 100% fish. The food code specifies a preparation method and gives
additional ingredients used in preparation of the dish. For example, in the Recipe File "Fish, floured or
breaded, fried" contains 84% fish, by weight. Fish dishes contained a wide range of fish; from
approximately 5% for a frozen "shrimp chow mein dinner with egg roll and peppers" to 100% for fish
consumed raw, such as raw shark.
4-74
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4.4 Intake of Methylmercury from Fish/fish Dishes
Estimates of methylmercury intake from fish and shellfish have been made based on dietary survey
data from the nationally representative surveys (CSFH 89-91, CSFH 94, CSFH 95, and NHANES HI).
Projected month-long estimates of fish/shellfish intake and mercury exposure have been developed from
the NHANES HI frequency of fish consumption data using data from the adult participants in NHANES in
and the 24-hour recall data from children and adults in NHANES ffl. These month-long projections are
considered to be the descriptions of mercury exposure from fish and shellfish that are most relevant to the
health endpoint used as the basis for the RfD; i.e. developmental deficits in children following maternal
exposure to methylmercury. Based on input from the interagency review a determination has been made
that comparison of 24-hour "per user" data is generally inappropriate and will not be done except when
describing subpopulations who eat fish/shellfish almost every day.
4.4.1 Intakes "per User" and "per Capita"
The data from major nationally based surveys of the general population are from CSFH 89-91,
CSFH 1994, CSFH 1995, and NHANES m conducted between 1988 and 1994. CSFH 89-91 obtained 3-
days of dietary history based on 24-hour recall interviews. CSFII1994 and CSFE 1995 obtained two days
of dietary history also obtained by 24-hour recall interview techniques. These two days of dietary recalls
were not necessarily sequential days. Interviewers in NHANES III obtained the respondents' estimate of
the number of times per day, per week, and per months the respondent consumed fish/shellfish over the
past 12-month period. These data were obtained only for persons 12 years of age and older. In addition,
recall data on fish/shellfish consumption were obtained on the same respondents as were questionnaire
responses of the frequency of food consumption. These recall data cover the 24-hour period prior to the
interview.
The number and percent of respondents reporting consumption of fish and/or shellfish in these
surveys in shown in Tables 4-55 to 4-57. Intake data can be expressed on a "per capita" basis which
reports the statistics calculated for all survey participants whether or not they reported consuming fish
and/or shellfish during the recall period. By contrast, "per user" statistics are calculated for only those
individuals who reported consuming fish and/or shellfish during the recall periods. The percent of survey
respondents who reported consuming fish and/or shellfish on one 24-hour recall ranged from 11.3 to
12.9% in the nationally-based contemporary food consumption surveys (Table 4-54).
Table 4-55
CSFII 89-91 Number of Respondents - AH Age Groups
Total
Fish Consumers
Ages 14 and
Younger
2893
720
Ages 15 through
45
4968
1510
Ages 46 and
Older
3545
1384
Total
11,706
3614
4-75
-------
Table 4-56
CSFII89-91 Adult Respondents
Gender
Males
Females
Ages 15 to 45 Years
2131
2837
Ages 46 Years and Older
1537
2308
Total for AH Age
Groups
3668
5145
Respondents Reporting Fish Consumption
Gender
Males
Females
Total
Ages 15 to 45 Years
646
864
1510
Ages 46 Years and Older
556
828
1384
Total for All Age
Groups
1202
1692
2894
Table 4-57
Contemporary Dietary Surveys 1990s
General U.S. Population
Survey
NHANES IH
CSFII 94 - Day 1
CSFII 94 - Day 2
CSFII 95 - Day 1
CSFII 95 - Da\ 2
Total Number of
Subjects
29,989
5,296
5,293
5063
5062
Number Reporting
Fish/shellfish
Consumption
3864
598
596
601
620
Percent Consuming
Fish/shellfish
12.9
11.3
11.3
11.9
12.2
4.4.1.1 "Per Capita" Consumption
"Per capita" data for CSFII 89-91 are shown in Table 4-58. Data in CSFII 89-91 reflect averages
calculated from three days of 24-hour recall data. Data for the more-recently conducted national surveys
are shown in Table 4-59. These data were obtained by interview and describe fish/shellfish consumption
in the previous 24-hour period. Interviewers describe two 24-hour recalls per respondent.
4-76
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Table 4-58
Per Capita Fish/Shellfish Consumption (gins/day) and
Mercury Exposure (ug/kg body weight/day) From CSFII 89-91
Based on Average of Three 24-Hour Recalls
Fish/shellfish
Consumption
Mercury
Exposure
25th
Zero
Zero
50th
Zero
Zero
75th
16
0.04
95th
73
0.24
Maximum
461
2.76
Table 4-59
Per Capita Fish/Shellfish Consumption
Based on Individual Days of 24-Hour Recall Data
General U.S. Population Surveys 1990s
Survey
CSFII 94 - Day 1
CSFII 94 - Day 2
CSFII 95 - Day 1
CSFII 95 - Day 2
NHANES III
10th
Zero
Zero
Zero
Zero
Zero
50th
Zero
Zero
Zero
Zero
Zero
90th
32
0.03
37
0.03
43
0.04
43
0.05
56
0.08
95th
85
0.13
85
0.14
105
0.13
98
0.17
114
0.19
Maximum
457
3.76
606
4.03
960
5.93
1084
2.63
1260
6.96
4.4.1.2 "Per User" Consumption
If statistics are calculated only on those individuals who reported consuming fish and/or shellfish
during the recall period "per user" values are calculated. Data from the average (i.e., mean) of three days
of 24-hour recalls reported in the CSFII 1989-1991 survey are shown in Table 4-60. Data for the
individual two days recorded in CSFII 1994 and in CSFII 1995, and for the single day's 24-hour recall in
NHANES in are shown in Table 4-61.
4-77
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Table 4-60
Per User Fish/Shellfish Consumption (grams per day) and
Mercury Exposure (fig/kg bw/day) Based
on Average of Three 24-Hour Recalls CSFII89-91
Fish/shellfish
Consumption
Mercury
Exposure
25th
19
0.04
50th
32
0.09
75th
57
0.18
95th
117
0.45
Maximum
461
2.76
Table 4-61
"Per User" Intake of Fish and Shellfish (gms/day) and Exposure to Mercury (ug Hg/kg bw/day)
Among Individuals Reporting Consumption, Based on Individual Day Recall Data
Study
CSFII 94 - Day 1
n=598
CSFII 94 - Day 2
n=596
CSFII 95 - Day 1
n=601
CSFII 95 - Day 2
n = 620
NHANES ffl
n=3,864
10th
28
0.02
26
0.03
28
0.03
24
0.03
22
0.01
50th
76
0.11
74
0.11
84
0.10
79
0.12
73
0.11
90th
186
0.43
200
0.40
197
0.42
216
0.47
242
0.44
95th | Maximum
252
0.65
282
0.65
261
0.61
285
0.64
336
0.63
458
3.76
606
1.03
960
5.93
1084
2.63
1260
6.95
4.4.2 Methylmercury Intake from Fish and Shellfish among Women of Child-bearing Age and Children
Subgroups at increased risk of exposure and/or toxic effects of mercury among the general
population include women of childbearing age and children. Exposures to women of childbearing age are
of particular interest because methylmercury is a developmental toxin (Tables 4-62 and 4-63).
4-78
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Table 4-62
"Per Capita" Fish/Shellfish Consumption (grams/day) and
Mercury Exposure (ug/kg bw/day) Based
on Average of Three 24-Hour Dietary Recalls CSFH 89-91
Females Aged 15-45
Fish/shellfish Consumption
Mercury Exposure
25th
Zero
Zero
50th
Zero
Zero
75th
15
0.03
95th
72
0.20
Maximum
Value
461
2.76
Table 4-63
"Per User" Fish/Shellfish Consumption (grams/day) and
Mercury Exposure (ug/kg bw/day) Based
on Average of Three 24-Hour Dietary Recalls CSFII89-91
Females Aged 15-45
Fish/shellfish Consumption
Mercury Exposure
25th
19
0.04
50th
31
0.08
75th
56
0.16
95th
113
0.33
Maximum
Value
461
2.76
Children consume more food on a body weight basis than do adults. Consequently children have
higher exposures to a variety of food contaminants (National Academy of Sciences, 1993 ) including
mercury. Overall, approximately 11 to 13 % of adults report fish/shellfish consumption in short-term
consumption estimates based on single 24-hour recall data. For children, the percent who report fish
consumption in similar surveys is about 8 to 9%.
Looking at the quantity of fish consumed and the intake of mercury on a body weight basis (i.e.,
ug Hg/kg body weight/day), the highest environmental dose of mercury from consumption of fish and
shellfish is found among children (Tables 4-64 and 4-65) based on fish intake and mercury exposures
estimated from single-day estimates. Exposure (on a per kg/bw basis) among children ages 10 and
younger are elevated compared with adult values. Children in the age range 11 through 14 years have
mercury doses (ug Hg/kg body weight/day) more comparable to adult values than to those of younger
children. When the NHANES III data are grouped by age category, exposure patterns shown in Table 4-64
are identified. Higher doses of mercury relative to body weight (ug/kg body weight/day) were also
observed in data from CSFII 94 and CSFII 95 (Table 4-66).
4-79
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Table 4-64
Consumption of Fish and Shellflsh (grams/day) and Mercury Exposure (ug Hg/kg bw/day) among
Different Age Categories of Children, Based on Individual Day Data
(Data from the NHANES III, 1988-1994)
Age Group, Years
Less than 2 years
50th Percenlile
90th Percentile
95th Percentile
3 through 6 years
50th Percentile
90th Percentile
95th Percentile
7 through 10 years
50th Percentile
90th Percentile
95th Percentile
11 through 14 years
50th Percentile
90th Percentile
95th Percentile
Fish Consumption
grams/day
29
95
115
43
113
151
77
178
270
63
158
215
Mercury Exposure
ug/kg body weight/day
0.33
0.98
1.33
0.28
0.77
1.08
0.31
0.86
1.08
0.15
0.42
0.68
Table 4-65
Fish and Shellfish Consumption (grams/day) and Mercury Exposure (ug/kg body weight/day)
for Children Aged 14 years and Younger CSFII 89-91
Based on Average of Three 24-Hour Recalls
Gender
25th
50th
75th
95th
Maximum
Value
"Per User"
Females
Males
13
0.08
14
0.09
24
0.17
23
0.17
38
0.34
43
0.29
75
0.85
87
0.63
154
1.69
139
1.51
"Per Capita"
Females
Males
Zero
Zero
Zero
Zero
Zero
Zero
Zero
Zero
7
Zero
5
0.01
43
0.39
52
0.33
155
1.69
139
1.51
4-80
-------
Table 4-66
"Per User" Fish and/or Shellfish Consumption (grams/day) and
Mercury Exposure (ug Hg/kg bw/day) by Children ages 14 and Younger
Based on Individual Day Data.
Survey
CSFH 94 - Day 1
n=148
CSFn 94 - Day 2
n=162
CSFII 95 - Day 1
n=126
CSFII 95 - Day 2
n=148
NHANES III
1988-1994
n= 1,062
10th
15
0.04
16
0.07
16
0.04
13
0.03
14
0.04
50th
53
0.13
53
0.20
57
0.23
53
0.23
51
0.25
90th
127
0.77
156
0.67
185
0.69
170
1.00
155
0.83
95th
176
1.06
171
0.91
204
0.81
243
1.98
185
1.08
Maximum
293
1.56
384
2.70
305
5.93
305
2.63
915
6.95
Comparison of the "per capita" and "per user" values indicate that Asian Americans and Pacific
Islanders consume fish and shellfish more frequently than other subpopulations. However, the quantity of
fish and shellfish consumed per person is actually smaller than for the other subpopulations Table 4-67).
If mercury exposure is expressed on a body weight basis (pg Hg/kg body weight), the exposures are more
comparable although Asian Americans/Pacific Islanders have lower exposure to mercury (on a body
weight basis) than do other ethnically diverse subpopulations (Table 4-67).
Table 4-67
Consumption of Fish and Shellfish (grams/day) and Mercury Exposure (ng Hg/kg bw/day)
Among Ethnically Diverse Groups, Based on Individual Day Recalls
(Source: CSFII 94 and CSFII95)
Ethnic Group
White
50th Percentile
90th Percentile
95th Percentile
Black
50th Percentile
90th Percentile
95th Percentile
Per Capita1
Fish
Consumption
^rams/day
Zero
24
80
Zero
48
104
Mercury
Exposure
fig/kg bw/day
Zero
0.03
0.14
Zero
0.05
0.19
Per User2
Fish
Consumption
grams/day
72
192
243
82
228
302
Mercury
Exposure
US/kg bw/day
0.12
0.46
0.67
0.14
0.54
0.96
4-81
-------
Table 4-67 (continued)
Consumption of Fish and Shellfish (grams/day) and Mercury Exposure (fig Hg/kg bw/day)
Among Ethnically Diverse Groups, Based on Individual Day Recalls
Ethnic Group
Asian and Pacific Islander
50th Percentile
90th Percentile
95th Percentile
Native American and Alaska
Native
50th Percentile
90th Percentile
95th Percentile
Other
50th Percentile
90th Percentile
95th Percentile
Per Capita1
Fish
Consumption
grams/day
Zero
80
127
Zero
Zero
56
Zero
Zero
62
Mercury
Exposure
fig/kg bw/day
Zero
0.15
0.30
Zero
Zero
0.03
Zero
Zero
0.13
Per User2
Fish
Consumption
grams/day
62
189
292
Estimate not
made because
of small
numbers of
respondents.
83
294
327
Mercury
Exposure
fig/kg bw/day
0.10
0.39
0.56
Exposures not
made because
of small
numbers of
respondents.
0.18
0.64
0.81
'Total number of 24-hour food consumption recall reports: White (16,241); Black (2,580); Asian and
Pacific Islander (532); Native American and Alaska Native (166): and Other (1,195).
- Number of 24-hour food consumption recall reports: White (1,821); Black (329); Asian and Pacific
Islander (155); Native American and Alaska Native (12); and Other (98).
4.4.3 Month-Long Estimates for Consumers
The third NHANES included survey questions on the frequency of consumption of fish and
shellfish that permitted nationally based estimates on how frequently people in the general United States
population consume fish and shellfish over a month-long period. The typical frequency of consumption
combined with a "snap shot" of typical consumption on any single day as shown in the "per user" 24-
hour recall data permit projection of moderate-term patterns of fish/shellfish consumption. It is these
moderate-term patterns that are the most relevant exposure period for the health-based endpoint that
formed the basis of the RfD - i.e., developmental deficits in children following maternal exposure to
methylmercury. Additional description of the particular importance of moderate-term patterns of mercury
exposure from fish/shellfish intakes is found in Section 4.1.1 (page 4-1 through 4-3 of this Volume).
The frequency of fish and shellfish consumption can be determined from the food frequency data
obtained in NHANES HI. By combining the number of times per month a person eats fish and shellfish
with the 24-hour recall data that provide an estimate of portion size and species of fish/shellfish selected, a
projection can be made of the consumption pattern over a month. The statistical methods describing how
4-82
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these two frequency distributions were combined is presented in Appendix D. The month-long projection
of fish/shellfish consumption for the general population is shown in Table 4-68a and 4-68b; the estimate
for women of childbearing age (assumed to be 15 through 44 years) is shown in Tables 4-69 and 4-70, and
the estimates for children are shown in Tables 4-71 and 4-72.
Table 4-68a
Month-Long Estimates of Fish and Shellfish Consumption (gins/day)
General Population by Ethnic/Racial Group
National Estimates Based on NHANES III Data
White/NonHispanic
Percentile
50th
75th
90th
95th
Percentile at
which
consumption
equals
approximately
]00jrams/day.
Fish/Shellfish
gms/day
8
19
44 '
73
97.3th
Percentile
Black/NonHispanic
Percentile
50th
75th
90th
95th
Percentile at
which
consumption
equals
approximately
100 grams/day.
Fish/Shellfish
gms/day
10
25
58
97
95.1th
Percentile
Other
Percentile
50th
75th
90th
95th
Percentile at
which
consumption
equals
approximately
1 00 grams/day.
Fish/Shellfish
gms/day
9
27
70
123
94.6th
percentile
Table 4-68b
Month-Long Estimates of Mercury Exposure (ug/kgbw/day)
Population by Ethnic/Racial Group
National Estimates Based on NHANES III Data
White/NonHispanic
Percentile
50th
75th
90th
95th
Mercury
Exposure
pg/kgbw/day
0.02
0.04
0.09
0.15
Black/NonHispanic
Percentile
50th
75th
90th
95th
Mercury
Exposure
jjg/kgbw/day
0.02
0.05
0.13
0.21
Other
Percentile
50th
75th
90th
95th
Mercury
Exposure
jig/kgbw/day
0.02
0.06
0.17
0.31
4-83
-------
Table 4-69
Month-Long Estimates of Exposure to Fish and Shellfish (gins/day)
for Women Ages 15 through 44 Years
Combined Distributions Based on NHANES III Data
Percentile
50th
75th
90th
95th
Percentile at which consumption
exceeds approximately 100 grams/day
based on month-long projections
Fish/Shellfish
(gms/day)
9
21
46
77
97th percentile
Table 4-70
Month-Long Estimates of Mercury Exposure (ug/kgfen'/day) for Women Ages 15 through 44
All Subpopulations Combined
National Estimates Based on NHANES III Data
Percentiles
50th
75th
90th
95th
99th
Mercury Exposure
ug/kgi iv/day
Month-Long Estimates
0.01
0.03
0.08
0.13
0.37
4-84
-------
Table 4-71
Month-Long Estimates of Fish/Shellfish Consumption (gms/day)
among Children Ages 3 through 6 Years.
National Estimates Based on NHANES III Data
Percentile
50th
75th
90th
95th
Per User Month-Long Estimate
Fish/Shellfish Consumption
(grams/day)
5
12
25
39
Mercury Exposure
(Hg/kgftn'/day)
0.03
0.08
0.18
0.29
Table 4-72
Month-Long Estimates of Exposure to Fish and Shellflsh (gms/day) and
Mercury (pg/kgbw/day) among Children Ages 3 through 6 Years
National Estimates for Individual Ethnic/Racial Groups
Percentile
50th
75th
90th
95th
Fish
(grams/day)
Mercury
(pgfkgbw/day)
Fish
(grams/day)
Mercury
(pg/kgbw/day)
Fish
(grams/day)
Mercury
(Hg/kgbw/day)
Fish
(grams/day)
Mercury
(ug/kg^H'/f/ajO
All Groups
5
0.03
12
0.08
25
0.18
39
0.29
White/
NonHispanic
5
0.03
11
0.08
24
0.17
37
0.28
Black/
NonHispanic
6
0.03
13
0.08
28
0.19
44
0.33
Other
7
0.04
17
0.11
36
0.25
57
0.42
4-85
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4.4.4 Habitat of Fish Consumed and Mercury Exposure from Fish of Marine. Estuarine and Freshwater
Origin
Fish and shellfish species have been grouped into those inhabiting marine, estuarine, and
freshwater environments. This classification was developed by US EPA's Office of Water based on advise
from fisheries biologists. Categories of fish and shellfish into those primarily inhabiting marine, estuarine,
and freshwater environments was shown in Table 4-17.
State and local authorities frequently have obtained data on mercury concentrations in fish in
waterways within their boundaries. Thirty-eight states in the United States have issued advisories
regarding mercury exposures that will occur through consumption of these fish. Nine states have state-
wide advisories that either are based primarily upon or include concern for mercury exposures from these
fish. At a local level, the mercury concentrations in fish vary widely. Exposures to methylmercury will
vary with the proportion of fish obtained from local sources and from interstate commerce.
Estimates have been made of a national pattern indicating the mixture of marine, estuarine, and
freshwater source of fish and shellfish. Tables 4-73 and 4-74 are based on the fish/shellfish consumption
data from NHANES III combined with the mercury concentration data of the NMFS and data reported by
Bahnick et al. (1988) on mercury concentrations in freshwater fish coming from a nationally based sample
of fish and shellfish. Consumption of fish and shellfish from a particular geographic site may result in
higher or lower exposures to methylmercury.
Among the three habitat types, overall consumption of freshwater fish and shellfish resulted in the
highest mercury exposure per kilogram body weight, followed by marine and estuarine fish and shellfish.
Men reported higher mercury exposures from freshwater fish than did women. The higher external doses
from freshwater fish are, in part, a reflection of larger serving sizes reported when freshwater species are
consumed.
Table 4-73
Exposure of Men Ages 15 to 44 Years to Mercury (ng Hg/kg bw/day)
from Fish and Shellfish of Marine, Estuarine, and Freshwater Origin
Based on Individual Day Recalls
(Food Consumption Data from NHANES HI and
Mercury Concentration Data from NMFS and Bahnick et al. (1988))
Statistic
Percentiles
10th
50th
90th
95th
Maximum
Values Reported
Marine
Origin
n=386
0
0.10
0.35
0.60
4.43
Estuarine
Origin
n = 198
0
0.03
0.30
0.44
0.71
Freshwater
Origin
n=60
0.01
0.33
1.26
1.37
1.91
Combined
Origin, i.e., Total
Exposure
n-644
0.01
0.11
0.44
0.60
4.43
4-86
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Table 4-74
Exposure of Women Aged 15-44 Years to
Mercury (fig Hg/kg bw/day) from
Fish and Shellfish of Marine, Estuarine, and Freshwater Origin
Based on Individual Day Recalls
(Food Consumption Data from NHANES III and
Mercury Concentration Data from NMFS and Bahnick et al. (1988))
Statistic
Percentiles
10th
50th
90th
95th
Maximum
Reported Value
Marine
Origin
n = 581
0.01
0.10
0.41
0.56
3.59
Estuarine
Origin
n = 221
0.01
0.03
0.14
0.23
0.39
Freshwater
Origin
n = 82
0.04
0.18
0.50
0.77
0.91
Combined
Origin, i.e., Total
Exposure
n = 882
0.01
0.10
0.39
0.53
3.59
4.4.5 Methylmercury Consumption
Quantities of methylmercury consumed in fish depend upon both the quantity of fish consumed
and the methylmercury concentration of the fish. Although they are infrequently consumed, swordfish,
barracuda and shark have a much higher methylmercury concentration than other marine finfish,
freshwater finfish or shellfish. By contrast most shellfish contain low concentrations of methylmercury
resulting in far lower methylmercury exposures than would occur if finfish species were chosen.
4.5 Conclusions on Methylmercury Intake from Fish
Methylmercury intakes calculated in this chapter have been developed for a nationally based
population rather than site-specific estimates. Food consumption data was provided from the CSFII 89/91,
CSFII 94, CSFII 95, and NHANES HI surveys. Methylmercury intakes calculated in this chapter have
been developed for a nationally based rather than site-specific estimates. The CSFII 89-91 from USDA
was designed to represent the U.S. population. The concentrations of methylmercury in marine fish and
shellfish were from a data base that is national in scope. Data on freshwater finfish were taken from two
large studies that sampled fish at a number of sites throughout the United States. The extent of
applicability of these data to site-specific assessments must rest with the professional judgments of the
assessor. Because of the magnitude of anthropogenic, ambient mercury contamination, the estimates of
methylmercury from fish do not provide a value that reflects methylmercury from nonindustrial sources.
"Background" values imply an exposure against which the increments of anthropogenic activity could be
added. This is not the situation due to release of substantial quantities into the environment.
Issues dealing with confidence in data on the methylmercury concentration of fish consumed
include the following:
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In a number of situations individuals cannot identify with accuracy the species of fish
consumed. The USDA Recipe File Data Base has "default" fish species specified if the
respondent does not identify the fish species consumed. There is no way, however to
estimate the magnitude of uncertainty encountered by misidentification of fish species by
the survey respondents.
The data base used to estimate methylmercury concentrations in marine fish and shellfish
was provided by the NMFS. This data base has been gathered over approximately the past
20 years and covers a wide number of species of marine fish and shellfish. The number of
fish samples for each species varies but typically exceeds 20 fish per species.
The analytical quality of the data base has been evaluated by comparison of these data
with compliance samples run for the U.S. FDA. The National Academy of Sciences'
Report on Seafood Safety and the U.S. FDA have found this data base from NMFS to be
consistent with 1990s data on methylmercury concentrations in fish.
The methylmercury concentrations in freshwater fish come from two publications, each
giving data that represent freshwater fish from a number of locations. These data were
gathered between the early 1980s and early 1990s. These surveys by U.S. EPA (1992),
Bahnick et al. (1994), and Lowe et al. (1985) report different mean mercury
concentrations; 0.260 ug/g mercury (wet weight) and 0.114 ug/g mercury (wet weight),
respectively. The extent to which either of these data sets represents nationally based data
on freshwater fish methylmercury concentrations remains uncertain.
Month-long estimates of mercury exposure from fish and shellfish consumption are
considered the exposure projection most relevant to the health endpoint of concern; i.e.,
developmental deficits among children following maternal fish consumption.
Because methylmercury is a developmental toxin, a subpopulation of interest is women of
child-bearing age. In this analysis of methylmercury intake, dietary intakes of women
aged 15 through 44 years were used to approximate the diet of the pregnant woman. From
data on Vital and Health Statistics, it has been determined that 9.5% of women of
reproductive age can be anticipated to be pregnant within a given year. Generally food
intake increases during pregnancy (Naismith, 1980). Information on dietary patterns of
pregnant women has been assessed (among other see Bowen, 1992; Greeley et al., 1992).
Most of these analyses have focussed on intake of nutrients rather than contaminants. It is
uncertain whether or not pregnancy would modify quantities and frequency of fish
consumed beyond any increase that may result from increased energy (i.e., caloric) intake
that typically accompanies pregnancy.
Based on available data on fish consumption in the 3 through 6 year age group, it is
estimated that 19 to 26% of these children consume relatively more fish on a per kilogram
per body-weight basis than do adults, which may result in higher mercury exposure these
children. The range reflects differences in mercury exposures between subpopulations
categorized on the basis of race and ethnicity. Persons of Asian/Pacific Islander, non-
Mexican Hispanics (largely persons of Caribbean ethnicity), Native Americans, and
Alaskan Natives have the highest exposures.
Because mercury concentrations in fish/shellfish are highly variable, information on
fish/shellfish consumption (grams/day) are also of interest. It is estimated that 3% of
4-88
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women have month-long fish/shellfish intakes of 100 grams per day and higher based on
the NHANES ffl data.
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5. POPULATION EXPOSURES - NON-DIETARY SOURCES
5.1 Dental Amalgams
Dental amalgams have been the most commonly used restorative material in dentistry. A typical
amalgam consists of approximately 50% mercury by weight. The mercury in the amalgam is continuously
released over time as elemental mercury vapor (Begerow et al., 1994). Research indicates that this
pathway contributes to the total mercury body burden, with mercury levels in some body fluids correlating
with the amount and surface area of fillings for non-occupationally exposed individuals (Langworth et al.,
1991;Olstadetal., 1987; Snappet al., 1989). For the average individual an intake of 2-20 ug/day of
elemental mercury vapor is estimated from this pathway (Begerow et al., 1994). Additionally, during and
immediately following removal or installation of dental amalgams supplementary exposures of 1-5 ug/day
for several days can be expected (Geurtsen 1990).
Approximately 80% of the elemental mercury vapor released by dental amalgams is expected to
be re-absorbed by the lungs (Begerow et al., 1994). In contrast, dietary inorganic mercury absorption via
the gastrointestinal tract is known the be about 7%. The contribution to the body burden of inorganic
mercury is thus, greater from dental amalgams than from the diet or any other source. The. inorganic
mercury is excreted in urine, and methylmercury is mainly excreted in feces. Since urinary mercury levels
will only result from inorganic mercury intake, which occurs almost exclusively from dietary and dental
pathways for members of the general public, it is a reasonable biomonitor of inorganic mercury exposure.
Urinary mercury concentrations from individuals with dental amalgams generally range from 1-5 u.g/day,
while for persons without these fillings it is generally less than 1 ug/day (Zander et al., 1990). It can be
inferred that the difference represents mercury that originated in dental amalgams.
Begerow et al., (1994) studied the effects of dental amalgams on inhalation intake of elemental
mercury and the resulting body burden of mercury from this pathway. The mercury levels in urine of 17
people aged 28-55 years were monitored before and at varying times after removal of all dental amalgam
fillings (number of fillings was between 4-24 per person). Before amalgam removal, urinary mercury
concentrations averaged 1.44 ug/g creatinine. In the immediate post-removal phase (up to 6 days),
concentrations increased by an average of 30%, peaking at 3 days post-removal. After this phase mercury
concentrations in urine decreased continuously and by twelve months had dropped to an average of 0.36
ug/g creatinine. This represents a four-fold decrease from pre-removal steady-state urinary mercury levels.
5.2 Occupational Exposures to Mercury
Industries in which occupational exposure to mercury may occur include chemical and drug
synthesis, hospitals, laboratories, dental practices, instrument manufacture, and battery manufacture
(National Institute for Occupational Safety and Health, (NIOSH) 1977). Jobs and processes involving
mercury exposure include manufacture of measuring instruments (barometers, thermometers, etc.),
mercury arc lamps, mercury switches, fluorescent lamps, mercury broilers, mirrors, electric rectifiers,
electrolysis cathodes, pulp and paper, zinc carbon and mercury cell batteries, dental amalgams, antifouling
paints, explosives, photographs, disinfectants, and fur processing. Occupational mercury exposure can
also result from the synthesis and use of metallic mercury, mercury salts, mercury catalysts (in making
urethane and epoxy resins), mercury fulminate, Millon's reagent, chlorine and caustic soda,
Pharmaceuticals, and antimicrobial agents (Occupational Safety and Health Administration (OSHA)
1989).
OSHA (1975) estimated that approximately 150,000 US workers are exposed to mercury in at
least 56 occupations (OSHA 1975). More recently, Campbell et al., (1992) reported that about 70,000
5-1
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workers are annually exposed to mercury. Inorganic mercury accounts for nearly all occupational
exposures, with airborne elemental mercury vapor the main pathway of concern in most industries, in
particular those with the greatest number of mercury exposures. Occupational exposure to methylmercury
appears to be insignificant. Table 3-10 summarizes workplace standards for airborne mercury (vapor +
paniculate).
A number of studies have been reported that monitored workers' exposure to mercury (Gonzalez-
Fernandez et al., 1984; Ehrenberg et al., 1991; Cardenas et al., 1993; Kishi et al., 1993,1994; Yang et al.,
1994). Some studies have reported employees working in areas which contain extremely high air
mercury concentrations: 0.2 to over 1.0 mg/m3 of mercury. Such workplaces include lamp sock
manufacturers in Taiwan (Yang et al., 1994), mercury mines in Japan (Kishi et al., 1993,1994), a small
thermometer and scientific glass manufacturer in the US (Ehrenberg et al., 1991), and a factory producing
mercury glass bubble relays (Gonzalez-Fernandez et al., 1984). High mercury levels have been reported
in blood and urine samples collected from these employees (reportedly over 100 ug/L in blood and over
200 - 300 ug/L or 100 - 150 ug/g creatinine for urine). At exposures near or over 1.0 mg/m3, workers
show clear signs of toxic mercury exposure (fatigue, memory impairment, irritability, tremors, and mental
deterioration). The chronic problems include neurobehavioral deficits that persist long after blood and
urine mercury levels have returned to normal; many workers required hospitalization and/or drug
treatments. With the exception of mercury mines, workplaces producing these mercury levels are typically
small and specialized, often employing only a few workers who were exposed to high mercury
concentrations.
Many other studies have monitored employees' work areas and reported measured mercury air
concentrations of 0.02 - 0.2 mg/m3; these levels are generally in excess of present occupational standards
(see Table 5-1). These mercury levels were most often reported at chlor-alkali plants (Ellingsen et al.,
1993; Dangwal 1993; Barregard et al., 1992; Barregard et al., 1991; Cardenas et al., 1993). Employees at
these facilities had elevated bodily mercury levels of approximately 10-100 ug/L for urine and about 30
ug/L in blood. At these lower levels, chronic problems persisting after retirement included visual response
and peripheral sensory nerve effects.
Exposures to mercury levels under 0.02 mg/m3 typically result in blood and urine levels
statistically higher than the general population, but health effects are usually not observed.
Table 5-1
Occupational Standards for Airborne Mercury Exposure
Concentration
Standard (mg/m3)
0.10
0.01
0.03
0.05
0.01
Standard Type
STEL
TWA
STEL
TWA
TWA
Mercury Species
inorganic
organic
alkyl
all besides alkyl
alkyl
Reference
CFR(1989)
CFR(1989)
CFR(1989)
ACGIH (1986)
ACGIH(1986)
5-2
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Table 5-1 (continued)
Occupational Standards for Airborne Mercury Exposure
Concentration
Standard (mg/m3)
0.03
0.10
0.05
Standard Type
STEL
TWA
TWA
Mercury Species
alkyl
aryl and inorganic
all besides alkyl
Reference
ACGIH(1986)
ACGIH (1986)
NIOSH (1977)
Abbreviations:
ACGIH - American Conference of Governmental Industrial Hygienists
CFR - Code of Federal Regulations
STEL - Short term exposure limit (15 minutes)
TWA - Time weighted average (8 hour workday)
5.3 Miscellaneous Sources of Mercury Exposure
Inorganic mercury is used in some ritualistic practices (Wendroff, 1995). The extent of this use in
the United States is undocumented, although it is considered to be more commonly encountered in
Hispanic and Latino communities. Inorganic mercury is distributed around the household in a variety of
ways and may result in dermal contact or it potentially be inhaled.
5.4 Cases of Mercury Poisoning
Numerous examples may be found in the literature of unintentional mercury poisoning. The
following examples were taken from Morbidity and Mortality Weekly Report, a publication of the U.S.
Public Health Service, Centers for Disease Control. These cases studies indicate that mercury has diverse
although, in many cases, illegal applications. The studies illustrate the wide range of potential health
effects from mercury exposure including death.
Unsafe Levels of Mercury Found in Beauty Cream
Between September 1995 and May 1996, the Texas Department of Health, the New Mexico
Department of Health, and the San Diego County Health Department investigated three cases of mercury
poisoning associated with the use of a mercury-containing beauty cream produced in Mexico. The cream,
marketed as "Crema de Belleza-Manning" for skin cleansing and prevention of acne, has been produced
since 1971. The product listed "calomel" (mercurous chloride) as an ingredient and contained 6% to 10%
mercury by weight. Because mercury compounds are readily absorbed through the skin, FDA regulations
restrict the use of these compounds as cosmetic ingredients. Specifically, mercury compounds can be used
only as preservatives in eye-area cosmetics at concentrations not exceeding 65 ppm of mercury; no
effective and safe nonmercurial substitute preservative is available for use in such cosmetics.
An ongoing investigation of the cream located it in shops and flea markets in the United States
near the U.S.-Mexico border, and identified a U.S. organization in Los Angeles as the distributor. Media
announcements, warning of the mercury containing cream, were then made in Arizona, California, New
Mexico, and Texas. In response to these announcements, 238 people contacted their local health
5-3
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departments to report using the cream. Urinalysis was conducted for 119 people, and of these, 104 had
elevated mercury levels. Elevated urine mercury levels were also detected in people who did not use the
cream but who were close household contacts of cream users.
Indoor Latex Paint Found to Contain Unsafe Mercury Levels
In August 1989, a previously healthy 4-year-old boy in Michigan was diagnosed with acrodynia, a
rare manifestation of childhood mercury poisoning. A urine mercury level of 65 ug/L was measured in a
urine sample collected over 24 hours. Examinations of his parents and two siblings also revealed elevated
urine mercury levels. The Michigan Department of Public Health (MDPH) determined that inhalation of
mercury-containing vapors from phenylmercuric acetate contained in latex paint was the probable route of
mercury exposure for the family; 17 gallons of the paint had been applied to the inside of the family's
home during the first week of July. During that month, the air conditioning was turned on and the
windows were closed, so that mercury vapors from the paint were not properly vented. In addition,
samples of the paint contained 930-955 mg/L mercury, while the EPA limit for mercury as a preservative
in interior paint is 300 mg/L.
In October, the Michigan Department of Agriculture prohibited further sales of the inappropriately
formulated paint, and the MDPH advised people not to use the paint, to thoroughly ventilate freshly
painted areas, and to consult a physician if unexplained health problems occurred. In November, the
MDPH and Centers for Disease Control began an ongoing investigation in selected communities in
southeastern Michigan to assess mercury levels in the air of homes in which this paint had been applied
and in urine samples from the occupants.
Jar of Mercury Spilled in Ohio Apartment
In November 1989, a 15-year-old male from Columbus, Ohio was diagnosed with acrodynia, a
form of mercury poisoning. A 24-hour urine collection detected a mercury level of 840 ug/L in the
patient's urine. The patient's sister and both his parents were also found to have elevated mercury urine
levels. Therefore, on November 29, the Columbus Health Department investigated the apartment where
the family had lived since August 26, 1989. Neighbors reported that the previous tenant had spilled a large
jar of elemental mercury within the apartment. Mercury vapor concentrations in seven rooms ranged from
50-400 ug/m\ The Agency for Toxic Substances and Disease Registry's acceptable residential indoor air
mercury concentration is less than or equal to 0.5 ug/m\
Mercury Vapors Released in House During Smelting Operation
On August 7, 1989, four adults from Michigan, ranging from age 40 to 88, were hospitalized for
acute mercury poisoning. All four patients lived in the same house, where one of the patients had been
smelting dental amalgam in a casting furnace in the basement of the house in an attempt to recover silver.
Mercury fumes were released during the smelting operation, entered air ducts in the basement, and were
circulated throughout the house. All four patients died of mercury poisoning within 11 -24 days after
exposure.
Mercury Spilled in Michigan House
During the summer of 1989, a boy in Michigan spilled about 20 cm3 of liquid mercury in his
bedroom. In September of that year, both of his sisters were diagnosed with mercury poisoning, after
exhibiting clinical symptoms associated with such poisoning. The boy, although asymptomatic, was also
tested and was found to have elevated mercury levels.
5-4
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Florida School Children Find Elemental Mercury in Abandoned Van
During August 1994, five children residing in a neighborhood in Palm Beach County, Florida
found 5 pints of elemental mercury in an abandoned van. During the ensuing 25 days, the children shared
and played with the mercury outdoors, inside homes, and at local schools. On August 25, 1994, a parent
notified local police and fire authorities that her children had brought mercury into the home. That same
day, 50 homes were immediately vacated and an assessment of environmental and health impacts was
initiated by the State of Florida Department of Environmental Protection, the Health and Rehabilitation
Services of the Palm Beach County Public Health Unit, and the U.S. Environmental Protection Agency.
A total of 58 residential structures were monitored for indoor mercury vapor concentrations;
unsafe indoor air levels of mercury (>15 ug/m3) were detected in 17. Several classrooms at the local high
schools were determined to be contaminated. In addition, 477 people were identified by the survey as
possibly exposed to mercury vapors and were evaluated at the emergency department of the local hospital
or the health department clinic for mercury poisoning. Of these people, 54 were found to have elevated
mercury levels.
Unsafe Mercury Levels Found in North Carolina Home
In July 1988, the Environmental Epidemiology Section of the North Carolina Department of
Environment, Health, and Natural Resources (DEHNR), investigated chronic mercury poisoning diagnosed
in a 3-year-old boy from North Carolina. Results of 24-hour urine specimens for mercury collected from
both the patient and his parents revealed elevated mercury levels. Although the family reported no known
mercury exposures, in April 1988, they had moved into a house whose previous owner had collected
elemental mercury. Several containers of mercury had reportedly been spilled in the house during the
previous owner's occupancy. As a result of the determination that the house was the probable source of
exposure, the family temporarily relocated.
The DEHNR conducted an extensive investigation of the house. Elevated mercury levels were
detected in five rooms and two bathrooms. The vacuum cleaner filter bag was tested for mercury as well,
and found to have extremely high mercury levels. The carpets were also heavily contaminated with
mercury. When the contaminated carpets were vacuumed, mercury particles and vapor were probably
dispersed throughout the house. Vaporization probably increased with the spread of the mercury and the
onset of warmer weather.
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6. COMPARISON OF ESTIMATED EXPOSURE WITH BIOMONITORING
6.1 Biomarkers of Exposure
Biologic markers, as described by the U.S. National Research Council (NRC, 1989) are indicators
signaling events in biological systems or samples. These are classified as biologic markers of exposure,
effect and susceptibility. A biological marker of exposure is defined by the National Research Council
(1989) an "exogenous substance or its metaboh'te(s) or the product of an interaction between a zenobiotic
agent and some target molecule or cell that is measured in a compartment within an organism" (NRC,
1989, pg. 2). Concentrations of mercury and of methylmercury in biological materials are used as
biomarkers of exposure to mercury in the environment.
Mercury accumulates in body organs. Although concentrations of mercury in organs adversely
affected by mercury (e.g., neural tissue, the kidney) may be more predictive of levels of exposure at the site
of organ system damage, for purposes of monitoring exposures mercury concentrations in tissues less
proximal are relied upon. Typically mercury concentrations in blood, hair, and urine are used to assess
exposure to organic and inorganic mercury.
6.2 Biomarkers of Exposure Predictive of Intake of Methylmercury
Humans are exposed to both organic (e.g., methylmercury) and inorganic mercury. The proportion
of organic to inorganic mercury exposure depends on exposure conditions. Organic methylmercury almost
exclusively occurs through consumption offish and shellfish. Occupational exposure to organic mercury
compounds is far less common than are occupational exposures to inorganic mercury compounds. Within
occupations where exposures to organic mercury compounds occur, great caution must be taken to assure
that people handling such compounds do not come into contact with organic mercury because of its
extreme toxicity. Inorganic mercury exposures reflect sources including dental amalgams and occupational
sources with minor contributions from certain hobbies and ritualistic uses of mercury. Contribution from
"minor" sources refers to their overall use in the general population. Such "minor" sources can produce
highly elevated exposures and poisoning of individuals who use these products.
Blood and hair concentrations of mercury can be used to back calculate estimates of
methylmercury ingested. Because methylmercury in the diet comes almost exclusively from consumption
of fish and shellfish, methylmercury concentrations in blood and hair are very strong predictors of
methylmercury ingestion from fish and shellfish.
The fraction of methylmercury absorbed via the gastrointestinal tract from fish and shellfish is
extremely high; typically more than 95% (REFS). After absorption methylmercury is transported in the
blood. There is a strong affinity for the erythrocyte (Aberg et al., 1969; Miettinen, 1971). Standard
reference values for blood mercury concentrations indicate packed cells are 10-times more concentrated in
mercury than is whole blood (Cornells et al., 1996). Methylmercury is distributed throughout the body
including distribution into the central nervous system. Postabsorption and distribution to tissues,
methylmercury is slowly demethylated and converted to inorganic mercury (Burbacker and Mottet, 1996).
A portion of the inorganic mercury arising from demethylation of methylmercury is present in
blood (Smith and Farris, 1996). Additional sources of inorganic mercury include dental amalgams in
persons with silver-mercury dental restorations, small amounts of inorganic mercury absorbed from diet,
and for some individuals occupational and/or miscellaneous sources. Although inorganic mercury is
present in blood, under most conditions the predominant chemical species of mercury in blood is
methylmercury arising from consumption of fish and shellfish.
6-1
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6.3 Sample Handling and Analysis of Blood Samples for Mercury
The predominant method of chemical analysis of total mercury in blood is based on cold vapor
absorbance techniques (IUPAC, 1996; Nixon et al., 1996). Atomic fluorescence is also a very sensitive
and reliable technique for mercury measurement in blood, serum and urine (IUPAC, 1996). The various
mercury-species are converted by reducing agents to elemental mercury and released as a vapor which is
either directly pumped through the cell of the atomic absorption spectrophotometer or analyzed after
amalgamation and enrichment on gold (IUPAC, 1996).
Sample pretreatment to destroy the organic matter in samples and avoid losses of mercury through
volatilization are key considerations in the analytic procedure for determination of inorganic and total
mercury. Digestion procedures have been developed that permit conversion of organic mercury
compounds and arylmercury to inorganic mercury, but do not convert significant quantities of
alkylmercury (i.e., methylmercury) to inorganic mercury (Nixon et al., 1996).
The expected concentration cited by IUPAC (1996) for mercury in serum of healthy individuals is
0.5 ug/L. In packed cells the level is about 5 fig/kg. Standard reference materials for mercury in whole
blood are available in the range of 4 to 14 ug/L. Using the IUPAC (1996) expected concentration, whole
blood mercury would be less than 2.5 ug/L.
Sample handling prior to analysis is always critical in obtaining optimal analytical results. The
Commission of Toxicology of the IUPAC has described an organized system for collection and handling of
human blood and urine for the analysis of trace elements including mercury (1996).
6.4 Association of Blood Mercury with Fish Consumption
6.4.1 Half-Lives of Methylmercury in Blood
The half-life of mercury in blood varies with prior intake of methylmercury and individual
characteristics. Previous investigations with methylmercury ingestion under controlled conditions provide
estimates of half-lives among adults. Data on half-lives among children do not appear to exist. Two
studies among adults are particularly informative. Sherlock et al. (1984) evaluated half-lives for
methylmercury ingested via halibut by 14 adult male and 7 adult female volunteers over a period of 96
days. Overall, the half-life for mercury in blood was calculated by Sherlock et al. as 50±1 days
(mean±standard error; range 42 to 70 days) for adult subjects. Another approach is that used by Birke et
al. (1972) based on repeated blood sampling of subjects after termination of chronic ingestion at higher
levels of methylmercury consumption. Data from the study of Birke et al. (1972) showed two subjects
with half-lives of 99 and 120 days in blood cells and 47 and 130 days in plasma. Additional data on half-
lives of methylmercury ingested via fish were reported by Miettinen et al. (1971) following single
ingestion of radiolabelled fish. Miettinen et al. (1971) using 203Hg-labelled methylmercury incorporated
into burbot (Lota vulgaris) fed as a single dose to 15 adult volunteers determined a mean biological half-
time of 50±7 days (mean±standard deviation of the mean) in red blood cells for five male subjects and one
female subject.
Overall the metabolic data support the use of blood mercury as an indicator of recent
methylmercury intake. The range surround mean half-lives reflect the combined influence of individual
person-to-person characteristics, previous intake of methylmercury, and level of methylmercury ingestion.
During the 1990s, a number of additional reports on total blood mercury and on organic methylmercury in
blood have confirmed that higher intakes of fish/shellfish are associated with increasing concentrations of
total mercury, and in particular a higher fraction of methylmercury (Mahaffey and Mergler, in press).
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6.4.2 Fraction of Total Blood Mercury that Is Organic or Methylmercurv
Among subjects with blood total mercury levels less than 5 ug/L, Oskarsson et al. (1996) reporting
on 30 women living in northern Sweden found that 26% of blood mercury was organic mercury. By
contrast women who consumed large amounts of seafood had 80% organic mercury at delivery in maternal
blood from Inuit women in Greenland (Hansen et al., 1990), and approximately 83% organic mercury in
Faroese women (Grandjean et al., 1992). High blood levels of total mercury were reported by Akagi et al.
(1995) among residents of the Amazon. In fishing villages where blood total mercury levels were
approximately 100 ug/L, 98% of total mercury was organic (methyl) mercury. Aks et al. (1995) in another
study of adult Amazon villagers, found approximately 90% of total mercury to be organic mercury when
blood levels were approximately 25 to 30 ug/L. Mahaffey and Mergler (in press) found that there was a
linear increase (when the data were log transformed) in the fraction of total blood mercury that was present
as organic mercury over a blood total mercury up to 70 ug/L.
6.4.3 Methylmercurv Consumption from Fish and Blood Mercury Values
Increasing frequency of fish consumption is predictive of higher total blood mercury
concentrations; particularly increased concentrations of organic mercury (i.e., methylmercury) in blood
(Brune et al., 1991; Hansen et al., 1990; Svensson et al., 1992; Weihe et al., 1996). Within the non-
occupationally mercury exposed population, frequency, quantity and species of fish consumed produce
differences in methylmercury ingestion and in blood mercury concentrations. Brune et al. (1991) reviewed
the literature on total mercury concentrations in whole blood and associated these with the number of fish
meals/week (Table 6-1). Although there is a clear increase in mean values with increasing frequency of
fish consumption, the ranges of values (e.g., 10th and 90th percentiles) overlap with the next highest
category of consumption. These ranges illustrate some of the difficulty of characterizing methylmercury
intake simply by the reports describing number of fish meals consumed per week.
Table 6-1
Literature Derived Values for Total Mercury Concentrations in Whole Blood
(from Brune et al., 1990)
Level of Fish
Consumption
Category I, No Fish
Consumption
Category II, < 2 Fish
Meals/Week
Category III, ;> 2-4 Fish
Meals/ Week
Mean Value
20
4.8
8.4
10th and 90th
Percentiles
0,4.3
2.4, 7.2
2.6, 14.2
25th and 75th
Percentiles
0.8, 3.2
3.5,6.1
5.4, 11.4
Number of
Observations
223
339
658
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Table 6-1 (continued)
Literature Derived Values for Total Mercury Concentrations in Whole Blood
(from Brune et al., 1990)
Level of Fish
Consumption
Category IV, > 4 Fish
Meals/Week
Category V, Unknown
Fish Consumption
Mean Value
44.4
5.8
10th and 90th
Percentiles
6.1,82.7
1.2, 10.4
25th and 75th
Percentiles
24.4, 64.4
3.4, 8.2
Number of
Observations
613
3182
The analysis by Brune et al. (1990) demonstrated the limitations of determining a methylmercury
intake based on the number of fish meals/week. Nonetheless there is an association between frequency of
fish meals and blood mercury levels. If the exposure analysis is further refined to include a description of
the size of the serving of fish consumed, and information on the mercury content of the fish, the
association with blood mercury concentration is strengthened.
6.4.4 North American Reports on Blood Mercury Concentrations
6.4.2.1
United States
Normative data to predict blood mercury concentrations for the United States population are not
available. With a very few exceptions all of the data that have been identified are for adult subjects. The
largest single study appears to be that of former United States Air Force pilots. Kingman et al. (Kingman
et al., in press; Nixon et al., 1996) analyzed urine and blood levels among 1127 Vietnam-era United States
Air Force pilots (all men, average age 53 years at the time of blood collection ) for whom extensive dental
records were available. Blood values were determined for total mercury, inorganic mercury and
organic/methylmercury. Mean total blood mercury concentration was 3.1 ug/L with a range of "zero" (i.e.,
detection limit of 0.2) to 44 ug/L. Overall, 75% of total blood mercury was present as
organic/methylmercury. Less than 1 % of the variability in total blood mercury was attributable to variation
in the number and size of silver-mercury amalgam dental restorations. Dietary data on the former pilots
were very limited, so typical patterns of fish consumption are not reported.
Additional North American studies have been reported by various individual states in the United
States. These are described below and summarized in Table 6-2.
Arkansas
The Arkansas Department of Health reported on total blood mercury for 236 individuals with a
mean of 10.5 ug/L (range "zero" to 75 ug/L) (Burge and Evans, 1996). Of these, 139 participants had
total blood mercury above 5 ug/L and 36 participants had blood mercury concentrations more than 20
ug/L. To have been included in the survey, subjects had to confirm that their fish consumption rate was a
minimum of two meals per month with eight ounces of fish per meal.
6-4
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Table 6-2
Blood Mercury Concentrations Values Reported for the United States
Study
Burge and Evans
(1996)
Centers for Disease
Control (1 993)
Gerstenberger et al.
(1997)
Harnly etal. (1997)
Community
236 participants
from Arkansas
Micousukee Indian
Tribe of South
Florida. 50 blood
samples from
subjects with mean
age=34 years
(Range 8 to 86
years).
68 Ojibwa Tribal
members from the
Great Lakes Region
Native Americans
living near Clear
Lake, California.
Group studied
include 44 Tribal
members, and 4
nontribal members.
Measure of
Central
Tendency
Mean: 10.5 ug/L;
among men: 12.8
ug/L; among
women, 6.9 ug/L.
Median: All
subjects 7.1 ug/L
Men: 9.0 ug/L
Women: 4.8 ug/L
Mean: 2.5 ug/L
Median: 1.6 ug/L
57 participants < 16
ug/L. Remaining
1 1 subjects
averaged 37 ug/L.
Mean for 44 Tribal
members: 18. 5 ug/L
(2.9 ug/L inorganic
Hg+ 15.6 ug/L for
organic Hg).
Mean for 4
nontribal members:
11. 5 ug/L (2.7 ug/L
inorganic + 8.8
ug/L organic Hg).
Maximum
All subjects: 75
ug/L
Males: 75 ug/L
Females: 27 ug/L.
13.8 ug/L
53 ug/L
Among Tribal
members: Total Hg
was 43.5 ug/L (4.7
ug/L inorganic +
38.8 ug/L organic).
For nontribal
members: Total Hg
15.6 ug/L (3.4 ug/L
inorganic + 12.2
ug/L organic).
Additional
Information on
Study
139 participants
exceeded 5 ug/L.
30 participants in
the range of 20 to
75 ug/L or 15%
>20 ug/L.
5% of menhad>30
ug/L. No women
had values > 30
Mg/L.
1 1 individuals had
blood mercury in
the range 20 to 53
ug/L.
20% of all
participants (9
persons including
four women of
childbearing age)
had blood mercury
concentrations > 20
Mg/L-
6-5
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Table 6-2 (continued)
Blood Mercury Concentrations Values Reported for the United States
Study
Humphrey and
Budd(1996)
Knobeloch et al.
(1995)
Schantz et al.
(1996)
Community
Lake Michigan
residents studied in
1971.
Family consuming
commercially
obtained seafood.
Adult men and
women aged 50 to
90 years. Michigan
residents.
Measure of
Central
Tendency
Algonac, Lake St.
Clair:
Fisheaters (n=42)
mean 36.4
compared with 65
low fish consumers
having mean of 5.7
Hg/L.
South Haven, Lake
Michigan with
lower Hg
contamination.
Fisheaters (n=54)
had mean 1 1 .8 (Jg/L
and the comparison
group of low fish
consumers mean
(n=42)of5.2ug/L
Initial blood values
for wife (37 ug/L)
and husband (58
Mg/L) following
regular
consumption of
imported seabass
having mercury
concentrations
estimated at 0.5 to
0.7 ppm Hg.
104 fisheaters:
mean=2.3 Mg Hg/L
84 nonfisheaters:
mean=l.l ug Hg/L.
Maximum
Algonac, Lake St.
Clair
Fisheaters: 3.0-95.6
Mg/L
Comparison:
1.1 -20.6 Mg/L
South Haven, Lake
Michigan
Fisheaters: 3.7-44.6
Mg/L
Comparison:
1.6-11.5 Mg/L
Six months after
family stopped
consuming seabass,
blood mercury
concentrations for
the wife (3 Mg/L)
and husband (5
Mg/L) had returned
to "background"
concentrations.
Maximum for
fisheaters: 20.5 Mg
Hg/L
Maximum for
nonfisheaters: 5.0
MgHg/L.
Additional
Information on
Study
Mercury
contamination less
intense in South
Haven compared
with Algonac.
Questionnaire on
fish-eating patterns
included sport-
caught Great Lakes
fish and purchased
fish, as well as
questions on
patterns of wild
game consumption.
6-6
-------
Great Lakes Region
Schantz et al. (1996) reported on blood mercury levels in an older-adult population (ages 50 to 90
years). Blood mercury levels for non-fisheaters averaged 1 . 1 ug/L and for fish-eaters the average was 2.3
Gerstenberger et al. (1997) determined blood mercury levels for 57 Ojibwas Tribal Members from
the Great Lakes Region. Among the 68 participants 57 had blood mercury concentrations < 16 ug/L. The
remaining 1 1 subjects had average blood mercury concentrations of 37 ug/L with a maximum value of 53
Wisconsin
Blood mercury levels among 175 Wisconsin Chippewas Indians who consumed fish from northern
Wisconsin lakes that have fish with high mercury concentrations (>1 ppm) were determined (Peterson et
al., 1994). Values ranged from nondetectable (i.e., < 1 ug/L) to a high of 33 ug/L. Twenty percent (64
individuals) had blood mercury levels > 5 ug/L. Recent consumption of the fish, walleye, was associated
with elevated blood mercury concentrations.
Knobeloch et al. (1995) investigated mercury exposure in a husband and wife and their two-year-
old son living in Wisconsin. The individuals had total blood mercury ranging from 37 to 58 ug/L- The
family's diet included three to four fish meals per week. The fish was purchased commercially from a
local market. Seabass were found to contain mercury at 0.5 to 0.7 ppm. Six months after the family
stopped consuming the seabass, blood mercury levels in this man and women declined dramatically to 5
and 3 ug/L, respectively.
California
Harnly et al. (1997) determined blood mercury concentrations for 44 members of Native American
tribes and 4 nontribal members living near Clear Lake, California. The mean for the 44 tribal members
was 1 8.5 ug/L total mercury (15.6 ug/L organic and 2.9 ug/L inorganic). The maximum value was 43.5
ug/L (38.8 ug/L organic and 4.7 ug/L inorganic). Twenty percent of all participants (including four
women of childbearing age) had blood mercury concentrations > 20 ug/L. Among nontribal members total
mercury concentrations were lower with a total mercury value of 1 1.5 (8.8 organic + 2.7 inorganic) ug/L.
The highest value for nontribal members was 15.6 (12.2 organic and 3.4 inorganic) ug/L.
Florida
The U.S. Centers for Disease Control (CDC, 1993) conducted a community survey of the tribal
representatives of the Miccousukee Indian Tribe living in South Florida. Blood mercury levels were
determined for 100 participants who were adult tribal members. Fish consumption among this group was
low with a maximum of approximately 170 grams/day and 3.5 grams calculated as a daily average. Total
blood mercury ranged from 0.2 to 13.8 ug/L with median and mean values of 1.6 and 2.5 ug/L,
respectively. There was a correlation between blood mercury levels and consumption of locally caught
fish.
Maine
An additional source of data on blood mercury levels is the heavy metal profiles (for lead, arsenic,
cadmium, and mercury) conducted as part of occupational surveillance. Typically the persons who receive
6-7
-------
this type of screening are expected to have exposures to at least one of these metals. Occupational
surveillance may be based on state requirements or Federal statutes. For example, the State of Maine has
an occupational disease reporting requirement on individuals whose blood mercury concentrations for total
mercury are 5 ug/L and higher and whose urinary total mercury is greater than or equal to 20 ug/L. The
State of Maine evaluated data on occupational screening for heavy metal exposure and identified a group
of adults having total blood mercury concentrations more than 5 ppb. Several cases of elevated blood
mercury concentrations were identified. One case has been reported by Dr. Allison Hawkes (personal
communication, 1997). The individual was identified with a blood mercury of 21.4 ug/L. The subject had
no known occupational exposure to mercury, but self-reported eating 3 or 4 fish meals per week. The
individual was asked to abstain from consuming fish for 4 or 5 weeks and then return for follow-up blood
testing. On retesting blood total mercury was only 5 ug/L.
6.4.2.1 Canadian
As in the United States, normative data for the general population of Canada have not been
identified in compiling information for this Report to Congress. By contrast to the United States,
information on mercury exposures in the northern regions of the country has been obtained. The
Department of Indian and Northern Affairs of the Government of Canada reported on Arctic contaminants
in the Canadian Arctic Contaminants Assessment Report in 1997. Methylmercury levels in blood since
1970. For all Aboriginal Peoples the mean blood mercury concentration was 14.13 (standard deviation
22.63) and a range of 1 to 660 ug/L (Wheatley and Paradis, 1995) based on 38,571 data points from 514
native communities across Canada.
Overall, blood mercury concentrations are considered closely tied to consumption of fish and
marine mammals. The highest levels are found among Aboriginal residents with particular high levels
found in northern Quebec and among the northern and eastern Inuit communities. No downward trend
was evident in Inuit blood mercury concentrations between 1975 and 1987, but more recent data (1992 to
1995) indicated lower levels of mercury in some groups (Jensen et al., 1997, page 336).
Quebec
Within the values reported in the Canadian Arctic Contaminants Assessment Report (Jensen et
al., 1997) particularly high mean concentrations were observed among the Inuit (Nunavik) of Quebec.
Mean total mercury concentration of 47 ug/L (SD 33, range 3 to 267 |Jg/L) was identified among 1114
Inuit of Quebec. The Northern (Cree) had mean values of 34 (SD 41, range 2 to 649 ug/L) among 4,670
blood values and 42.9 (SD 52, range 2 to 649) based on 1,129 blood values.
North West Territory
The Nunavut (Inuit) of the North West Territory also have elevated blood mercury levels with
mean values during the 1970s through late 1980s averaging between 17 and 40 ug/L (upper extent of this
range going to 226 ng/L). The Western (Dene) population had lower blood mercury levels with means
between 11 and 17 ug/L (upper extent of the Dene range to 138 ug/L).
6.5 Hair Mercury as a Biomarker of Methylmercury Exposure
6.5.1 Hair Composition
Hair is approximately 95% proteinaceous and 5% a mixture of lipids, glycoproteins, remnants of
nucleic acids, and in the case of pigmented hairs, of melanin and phaeomelanin. Hair contains a central
6-8
-------
core of closely packed spindle-shaped cortical cells, each filled with macrofibrils which in turn consist of a
microfibril/matrix composite. The long axes of the cells and their fibrous constituents are oriented along
the long axis of the hair. The amino acid composition of hair is high in those amino acids with side-chains
(particularly, those containing "reactive" groups such as cystine, cysteine, tyrosine, tryptophan, acidic and
basic amino acids, as well as terminal carboxyl or amino groups). The cortical core is covered by sheet-
like cells of the cuticle. The surfaces of all the cells of the hair shaft have a thin layer of lipid which is
covalently attached to the underlying proteins.
Hair has been assumed to grow at the rate of one centimeter a month (Kjellstrom et al., 1989;
Marsh et al., 1980). However, there is variability in the rate of hair growth. Growth determined
experimentally is between 0.9 and 1.3 cm per month (Barman et al., 1963; Munro, 1966; and Saitoh,
1967).
Mercury is incorporated into hair during the growth of hair. Hair mercury concentrations are
presumed to reflect blood mercury concentrations at the moment of hair growth. Whether the predominant
chemical species is inorganic mercury or methylmercury depends on exposure patterns and on the extent of
demethylation of methylmercury. Hair mercury (ug/g) and blood mercury (ng/L) ratios range from 190:1
up to 370:1 (Skerfving, 1974; Phelps et al., 1980; Turner et al., 1980; Sherlock et al., 1984). Higher ratios
have recently been reported. Additional discussion of the hair to blood mercury ratio is found in the
volume on human health. This is one source of person-to-person variability considered in selection of
uncertainty factors in determining U.S. EPA's Reference Dose for methylmercury.
Chemical analyses to determine mercury concentrations in hair determine total mercury rather than
chemical species of mercury. In order to dissolve hair samples, they must be put through an acid digestion.
The process of acid digestion will convert virtually all of the mercury in the biological sample to inorganic
mercury (Nixon et al., 1996). Consequently the fraction of hair mercury that is methylmercury is only an
estimate based on what is known of environmental/occupational exposure patterns.
The frequency of fish consumption has been used as a guide to differences in hair mercury
concentrations (Airey, 1983). Within a general population as fish consumption increases, hair mercury
concentration will also increase. However, the amount of mercury in hair depends on the concentration of
mercury present in fish consumed. Comparison of recent studies from Bangladesh (Holsbeek et al., 1996)
and Papua New Guinea (Abe et al., 1995) illustrates these differences. Holsbeek et al. (1996) found a
highly significant positive correlation (r=0.88, P<0.001) between fish consumption and hair mercury
concentrations. Total hair mercury concentrations had a mean value of 0.44±0.19 ug/g (range 0.02 to
0.95) and a fish consumption of 2.1 kg/month (range 1.4 to 2.6). The low concentrations in hair reflect the
low concentrations of methylmercury in Bangladesh fish. Abe et al. (1995) evaluated 134 fish-consuming
subjects and 13 nonfish-eating subjects in Papua, New Guinea. Among the fish consumers hair mercury
levels had a mean mercury concentrations of 21.9 ug/g (range 3.7 to 71.9). Average fish consumption was
280 grams/day (range=52 to 425) or about 8.4 kg/month producing an average methylmercury intake of 84
ug/day. Among the nonfish consumers the mean hair mercury was 0.75+0.4 ug/g. The difference in hair
mercury concentration in Bangladesh and New Guinea were considerably greater than the differences in
fish mercury.
6-9
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6.5.2 Hair Mercury Concentrations in North America
6.5.2.1 United States
Data do not exist describing hair mercury concentrations that are representative of the United
States population as a whole. This is similar to the situation for blood mercury concentrations. Limited
data from smaller studies are described below and summarized in Table 6-3.
U.S. Communities
Crispin-Smith et al. (1997) analyzed hair mercury concentrations in 1431 individuals living in the
United States. The communities in which these individuals resided were not identified. Mean values in
these studies were < 1 ug/g. Fish consumers had slightly higher blood mercury concentrations than did
nonfish consumers (0.52 vs. 0.48). The maximal value reported in this survey was 6.3 ug/g. Statistical
information on these data is not available currently.
New York Metropolitan Area, New Jersey, Alabama (Birmingham), and North Carolina
(Charlotte)
Creason et al. (1978a, 1978b, and 1978c) evaluated children and adults living in these cities in the
early 1970s. Mean values for all groups of children and adults were less than 1 ug/g. Maximum values
were in the range of 5 to 11.3 ug/g of hair. Adult values were slightly higher than those of children.
California
Airey (1983) determined hair mercury concentrations among about 100 subjects living in Southern
California (LaJolla and San Diego). Mean values were in the range of 2 to 3 ug Hg/gram, with maximum
values in the range of 4.5 to 6.6 Mg/g.. Harnly et al. (1997) determined hair mercury among Tribal and
nontribal group members living near Clear Lake, California. Mean values were typically less than 1 ug/g.,
with maximum values of 1.8 ug/g. among Tribal members and 2.3 ug/g among non-Tribal members.
Maryland
Airey (1983) found mean concentrations of about 1.5 to 2.3 ug/g in adults living in Maryland
(communities were not identified). Maximum concentrations were 4.5 ug/g..
State of Washington
Lazaret et al. (1991) identified hair mercury concentrations < 1 ug/g. and a maximum value of 1.5
ug/g. Earlier Airey (1983) reported mean values of 1.5 to 3.8 ug/g among small numbers of subjects. The
maximum value reported was 7. 9 |ag/g.
Florida
CDC (1993) surveyed 330 subjects living in the Florida Everglades and determined that average
hair mercury concentrations were 1.3 ug/g.. The maximum value was 15.6 ug/g.
6-10
-------
Wisconsin
Knobeloch et al. (1995) reporting on two individuals with blood mercury concentrations of 38 and
>50 ug/g. found the individuals hair mercury concentrations were 11 and 12 (jg/g.
Great Lakes Region
Gerstenberger et al. (1997) determined mean mercury concentrations were less than one ug/g.
among 78 Ojibwa Tribal members. The maximum hair mercury concentration was 2.6 ug/g.
Alaska
Lazaret et al., (1991) reported hair mercury concentrations averaging 1.4 ug/g among 80 women of
childbearing age. The maximum hair mercury concentrations were 15.2 ug/g.
Table 6-3
Hair Mercury Concentrations (ug Hg/gram hair or ppm) from Residents
of Various Communities in the United States
Study
Creason et al.,
1978a
Creason et al.,
1978b
Creason et al.,
1978c
Community
New York
Metropolitan Area
Four communities in
New Jersey:
Ridgewood,
Fairlawn. Matawan
and Elizabeth
Birmingham,
Alabama, and
Charlotte, North
Carolina
Mean
Concentration
Children (n=280);
0.67 ppm
Adults (n=203);
0.77
Children (n=204).
0.77 ppm
Adults (n=l 17),
0.78 ppm
Children (n=322),
0.46 ppm
Adults (n- 11 7) 0.78
ppm
Maximum
Concentration
Children, 1 1.3 ppm
Adults, 14.0 ppm
Children, 4.4 ppm
Adults, 5. 6 ppm
Children, 5.4 ppm;
Adults, 7.5 ppm
Additional
Information on
Study
Survey conducted
in 1971 and 1972
Survey conducted
in 1972 and 1973
Survey conducted
in 1972 and 1973
6-11
-------
Table 6-3 (continued)
Hair Mercury Concentrations (ug Hg/gram hair or ppm) from Residents
of Various Communities in the United States
Study
Airey, 1983
Airey, 1983
Airey, 1983
Community
U.S. data cited by
Airey, 1983.
Community not
identified.
U.S. data cited by
Airey, 1983
Community
identified: LaJolla-
San Diego
U.S. data cited by
Airey, 1983. Area
identified: Maryland
Mean
Concentration
1) Males (n=22),
2.7 ppm;
2). Females (n=16),
2.6 ppm;
3) Males and
Females (24
subjects), 2.1 ppm;
4) Males and
Females (3 1
subjects), 2.2 ppm;
5) Males and
Females 924
subjects) 2.9 ppm;
6) Males and
Females (79
subjects), 2.4 ppm.
1) 2.4 ppm (13
men);
2) 2.7 ppm (13
women);
3) 2.3 ppm (8
subjects including
men and women);
4) 2.9 ppm (17
subjects including
men and women);
5) 2.6 ppm (5
subjects including
men and women);
6) 2.8 ppm (30
subjects including
men and women).
1) 1.8 ppm (11
subjects, men and
women);
2) 1.5 ppm (11
subjects, men and
women);
3) 2.3 ppm (11
subjects, men and
women);
4) 1.9 ppm (33
subjects, men and
women).
Maximum
Concentration
1) 6.2 ppm
2) 5.5 ppm
3) 5.6 ppm
4) 6.6 ppm
5) 7.9 ppm
6) 7.9 ppm
1) 6.2 ppm
2) 5.5 ppm
3) 4.5 ppm
5) 6.2 ppm
6) 6.6 ppm
1) 3. 8 ppm
2) 3. 9 ppm
3) 4.5 ppm
4) 4.4 ppm
Additional
Information on
Study
6-12
-------
Table 6-3 (continued)
Hair Mercury Concentrations (ug Hg/gram hair or ppm) from Residents
of Various Communities in the United States
Study
Airey, 1983
Crispin-Smith et
al., 1997
Lasoraet al., 1991
Lasoraet al., 1991
Fleming et al.,
1995
Knobeloch et al.,
1995
Community
U.S. data cited by
Airey, 1983
Community
identified: Seattle.
U.S., Communities
and distribution not
identified
Nome, Alaska
Sequim, Washington
Florida Everglades
Wisconsin, urban
Mean
Concentration
1)3. 3 ppm (9 men);
2. 2.2 ppm (3
women);
3) 2.6 ppm (5
subjects men and
women);
4) 1.5 ppm (3
subjects, men and
women);
5) 3. 8 ppm (8
subjects, men and
women);
6) 3.0 ppm (16
subjects, men and
women).
0.48 ppm (1,431
individuals);
0.52 ppm (1009
individuals
reporting some
seafood
consumption)
1.36 ppm
(80 women of
childbearing age)
0.70 ppm (7 women
of childbearing age)
1.3 ppm (330
subjects, men and
women)
2 adults (1 man, 1
woman); values 1 1
and 1 2 ppm
Maximum
Concentration
1) 5.6 ppm
2) 4.1 ppm
3) 5.6 ppm
4) 2.1 ppm
5) 7.9 ppm
6) 7.9 ppm
6.3 ppm
15.2 ppm
1 .5 ppm
15.6 ppm
Additional
Information on
Study
The 1009
individuals are a
subset of the 1431
subjects.
To be included in
the survey the
subjects had to have
consumed fish or
wildlife from the
Everglades.
6-13
-------
Table 6-3 (continued)
Hair Mercury Concentrations (ug Hg/gram hair or ppm) from Residents
of Various Communities in the United States
Study
Gerstenberger et
al., 1997
Harnlyetal., 1997
Community
Ojibwa Tribal
members from the
Great Lakes Region
Native Americans
living near Clear
Lake, California.
Mean
Concentration
47% > 0.28 ppm.
Among individuals
with values above
the level of
detection, the mean
was 0.83 ppm based
on 78 subjects
68 Tribal members.
Mean value: 0.64
ppm.
4 non-Tribal
members. Mean
value: 1.6 ppm
Maximum
Concentration
2.6 ppm
Maximum value for
Tribal members:
1.8 ppm
Maximum value for
non-Tribal
members: 2.3 ppm
Additional
Information on
Study
6.5.2.2 Summary of Data on Hair Mercury Concentrations
Available data indicate that mean mercury concentrations in the U.S. population are typically less
than 3 ug/g and often less than 1 ug/g, although, maximum concentrations of more than 15 ug/g are
reported. Hair mercury concentrations of greater than 10 ug/g have been associated with mercury
exposure from fish. The shape of the distribution of hair mercury concentrations in the United States is not
well documented. Comparison of data summarized by Airey (1983) on the association between frequency
of fish meals, mean and range of hair mercury concentrations reveals (see Table 6-4):
The arithmetic mean of hair mercury from the U.S. surveys is consistent with the lower
bound of the range associated with fish ingestion rates of less than once a month to as
frequent as once a week.
The maximum values identified in the surveys are consistent with fish consumption of
every week to every day.
Table 6-4
Association of Hair Mercury Concentrations (ug Hg/gram hair) with
Frequency of Fish Ingestion by Adult Men and Women
Living in 32 Locations within 13 Countries (Airey, 1983)
Frequency of Fish Meals
Once a Month or Less
Twice a Month
Every Week
Every Day
Arithmetic Mean
1.4
1.9
2.5
11.6
Range
0.1-6.2
0.2-9.2
0.2-16.2
3.6-24.0
6-14
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6.6 Conclusions
6.6.1 Blood Mercury Levels
Mercury in blood is a reflection of exposures in recent days and weeks to environmental mercury.
Typically blood mercury values are reported as total mercury, although chemically speciated mercury
analyses often are included in reports published in the 1990s. Organic mercury in blood generally reflects
methylmercury intake from fish and shellfish. At progressively higher dietary intakes of fish and shellfish,
the fraction of total blood mercury that is organic mercury increases becoming more than 95% at high
levels of fish consumption.
Blood mercury concentrations (ug Hg/L) in healthy populations are less than 3 ug/L (5 ug/kg
packed cells and 0.5 ug/L serum) based on values published by the International Union for Pure and
Applied Chemistry (1996). The U.S. EPA RfD is associated with a whole blood mercury concentration of
4 to 5 ug/L. The "benchmark dose" for methylmercury used in setting the RfD is 44 ug/L based on
neurotoxic effects observed in Iraqi children exposed in utero.
There are no representative data on blood mercury for the U.S. population as a whole. In the
United States (in the peer-reviewed literature published in the 1990s), blood mercury concentrations in die
range of 50 to 95 ug/L have been reported and attributed to the consumption of fish and shellfish. Among
groups of anglers and Native American Tribal groups, mean blood mercury levels in the range of 10 to 20
ug/L have been reported. Blood mercury concentrations greater than 20 ug/L and attributable to
consumption of fish and shellfish have been identified among women of childbearing age in the United
States.
6.6.2 Hair Mercury Levels
Mercury is incorporated in hair as it grows. Typically the centimeter of hair nearest the scalp
reflects mercury exposure during the past month. The extent to which the predominant chemical species
in hair is a function of methylmercury exposure depends on environmental exposure patterns.
Methylmercury in the diet results in elevated hair mercury concentrations. Dietary sources documented to
produce elevated hair mercury concentrations include fish, shellfish, and flesh from marine mammals.
There are no representative data on hair mercury concentrations for the U.S. population as a
whole. Typical values in the United States are less than 1 ug/g. Maximum hair mercury concentrations of
15 ug/gram and higher have been reported in the United States. Hair mercury concentrations greater than
10 ug/gram have been reported for women of childbearing age living in the United States. U.S. EPA's
RfD is associated with a hair mercury concentration of approximately 1 ug/g. The "benchmark" dose is
associated with a hair mercury concentration of 11.1 ug/g and is based on neurotoxic effects observed in
Iraqi children exposed in utero to methylmercury.
6-15
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7. CONCLUSIONS
The results of the current exposure of the U.S. population from fish consumption indicate that
most of the population consumes fish and is exposed to methylmercury as a result. Approximately
85% of adults in the United States consumer fish and shellfish at least once a month with about
half of adults selecting fish and shellfish as part of their diets at least once a week (based on food
frequency data collected among more than 19,000 adult respondents in the NHANES III
conducted between 1988 and 1994). This same survey identified 1-2% of adults who indicated
they consume fish and shellfish almost daily.
For the modeled fish ingestion scenarios, the local emission sources are predicted to account for
the majority of the total mercury exposure for water bodies close to the sources. This is
particularly true for the hypothetical western site, where background and regional atmospheric
contributions to the total mercury concentration in the water column are predicted to be lower.
Consumption of fish is the dominant pathway of exposure to methylmercury for fish-consuming
humans. There is a great deal of variability among individuals in these populations with respect to
food sources and fish consumption rates. As a result, there is a great deal of variability in
exposure to methylmercury in these populations. The anthropogenic contribution to the total
amount of methylmercury in fish is, in part, the result of anthropogenic mercury releases from
industrial and combustion sources which increases mercury body burdens in fish. As a
consequence of human consumption of the affected fish, there is an incremental increase in
exposure to methylmercury. Terrestrial exposures were evaluated in the modeling analysis;
inorganic mercury species were predicted to be the dominant chemical species to which homans
are exposed.
In the nationally-based dietary surveys, the types of fish most frequently reported to be eaten by
consumers are tuna, shrimp, and Alaskan pollock. The importance of these species is
corroborated by U.S. National Marine Fisheries Service data on per capita consumption rates of
commercial fish species.
National surveys indicate that Asian/Pacific Islander-American and Black-American
subpopulations report more frequent consumption of fish and shellfish than other survey
participants.
Superimposed on this general pattern offish and shellfish consumption is freshwater fish
consumption, which may pose a significant source of methylmercury exposure to consumers of
such fish. The magnitude of methylmercury exposure from freshwater fish varies with local
consumption rates and methylmercury concentrations in the fish. The modeling exercise indicated
that some of these methylmercury concentrations in freshwater fish may be elevated as a result of
mercury emissions from anthropogenic sources. Exposures may be elevated among some
members of this subpopulation; these may be evidenced by analyses of blood mercury showing
concentrations in excess of 10 micrograms per liter (ug/L) that have been reported among multiple
freshwater fish-consumer subpopulations. The mean value of blood mercury in an Arkansas study
was lOug/L. Because general populations data on the distribution of blood mercury
concentrations have not been gathered, it is not known how common blood mercury concentration
above lOug/L are.
7-1
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An assessment of consumption offish and shellfish was based on data obtained from
contemporary nationally based dietary surveys conducted by the United States government: the
third National Health and Nutrition Examination Survey conducted between 1988 and 1994
(National Center for Health Statistics of the Centers for Disease Control) and the 1994 and 1995
Continuing Surveys of Food Intakes by Individuals (United States Department of Agriculture).
Data on mercury concentrations in fish and shellfish were obtained from national database
compiled by the National Marine Fisheries Service and the U.S. Environment Protection Agency.
The results of the assessment show that the predicted average exposure among make and female
fish consumers of reproductive age is 0.1 micrograms of methylmercury per kilogram of body
weight per day based on a single day's estimate. The comparable 90th percentile estimate is
approximately four times this level. Median "per user" fish/shellfish consumption values across
these nationally representative surveys were between 73 and 79 grams/day based on single-day
estimates. The comparable 90th percentile values ranged between 186 and 242 grams/day based
on single-day estimates.
The single-day estimates are used to project month-long fish/shellfish consumption when
combined with frequency of fish/shellfish consumption estimates obtained from adult participants
in NHANES HI. The single-day estimates of fish/shellfish consumption provide portion sizes to
estimated the impact of intermittent consumption of fish containing mercury at concentrations
considerably above that commonly encountered in the commercial market, e.g., approximately 0.5
ppm and higher. Fish with mercury concentrations averaging over 0.5 ppm include swordfish and
shark among marine fish and smallmouth bass, largemouth bass, channel catfish, walleye, and
northern pike among freshwater fish.
Exposure rates to methylmercury among fish-consuming children are predicted to be higher than
for fish-consuming adults on a body weight basis. The 50th percentile exposure rate among fish-
consuming children ages 3 through 6 years is approximately 0.3 micrograms per kilogram of body
weight per day based on single day estimates. Predicted exposures at the 90th percentile are
approximately three-times greater or 0.8 to one microgram of mercury per kilogram of body weight
on a single day. Estimated month long mercury exposures among 3 through 6 year-old children
are 0.03 at the 50th percentile and 0.17 at the 90th percentile using adult data to predict how often
children consume fish and shellfish. It is uncertain how well the adult data are predictive for
children because data for children are not available.
Exposures among specific subpopulations including anglers, Asian-Americans, and members of
some Native American Tribes indicate that their average exposures to methylmercury may be more
than two-times greater than those experience by the average population.
Predicted high-end exposures to methylmercury are caused by one or two factors or their
combination: 1) high consumption rates of methylmercury contaminated fish, water and/or 2)
consumption of types of fish which exhibit elevated methylmercury concentrations in their tissues.
Of these two factors the former appears to be more significant for overall population exposures.
Blood mercury concentrations and hair mercury levels are biomarkers used to indicate exposure to
mercury. Inorganic mercury exposures occur occupationally and for some individuals through
folk/hobby exposures to inorganic mercury. Dental restorations with silver-mercury amalgams can
also contribute to inorganic mercury exposures. Methylmercury exposure is almost exclusively
through consumption of fish, shellfish, and marine mammals. Occupational exposures to
methylmercury are rare.
7-2
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Data describing blood and/or hair mercury for a population representative of the United States do
not exist, however, some data are available. Blood mercury concentrations, attributable to
consumption of fish and shellfish, in excess of 30 jag/L have been reported in the United States.
Hair mercury concentrations in the United States are typically less than lug/g, however, hair
mercury concentration greater than lOu/g have been reported for women of childbearing age living
in the United States. U.S. EPA's RfD is associated with a blood mercury concentration of 4-5
ug/L and a hair mercury concentration of approximately Ipg/g. The "benchmark" dose is
associated with mercury concentrations of 44|jg/L in blood and 11.1 pg/g in hair. The
"benchmark" dose for methylmercury is based on neurotoxic effects observed in Iraqi children
exposed in utero to methylmercury.
To improve the quantitative exposure assessment modeling component of the risk assessment for
mercury and mercury compounds, U.S. EPA would need more and better mercury emissions data
and measured data near sources of concern, as well as a better quantitative understanding of
mercury chemistry in the emission plume, the atmosphere, soils, water bodies, and biota.
To improve the exposure estimated based on surveys of fish consumption, more study is needed
among potentially high-end fish consumers, which examines specific biomarkers indicating
mercury exposure (e.g., blood mercury concentrations and hair mercury concentrations).
A pharmacokinetic-based understanding of mercury partitioning in children is needed. Additional
studies offish intake and methylmercury exposure among children are needed.
7-3
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8. RESEARCH NEEDS
To improve the quantitative exposure assessment modeling component of the risk assessment for
mercury and mercury compounds, U.S. EPA would need more and better mercury emissions data
and measured data near sources of concern, as well as a better quantitative understanding mor
mercury chemistry I the emission plume, the atmosphere, soils, water bodies, and biota.
To improve the exposure estimated based on surveys of fish consumption, more study in needed
among potentially high-end fish consumers, which examines specific biomarkers indicating
mercury exposure (e.g., blood mercury concentrations and hair mercury concentrations).
A pharmacokinetic-based understanding of mercury partitioning in children is needed. Additional
studies of fish intake and methylmercury exposure among children are needed.
8-1
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APPENDIX A
EXPOSURE PARAMETER JUSTIFICATIONS
-------
TABLE OF CONTENTS
DISTRIBUTION NOTATION ^ iii
A. SCENARIO INDEPENDENT PARAMETERS A-l
A.I Chemical Independent Parameters A-l
A.1.1 Basic Constants A-l
A.I .2 Receptor Parameters A-l
A.l.2.1 Body Weight A-2
A. 1.2.2 Exposure Duration A-2
A.I.3 Agricultural Parameters A-3
A.I.3.1 Interception Fraction A-3
A.I .3.2 Length of Plant Exposure A-4
A.l.3.3 Plant Yield A-5
A.I.3.4 Plant Ingestion by Animals A-6
A. 1.3.5 Soil Ingestion by Animals A-7
A.I .4 Exposure Parameters A-7
A.I.4.1 Inhalation Rate A-8
A. 1.4.2 Consumption Rates A-9
A.I.4.3 Soil Ingestion Rate A-10
A.I .4.4 Groundwater Ingestion Rate A-l 1
A. 1.4.5 Fish Ingestion Rate A-J 2
A. 1.4.6 Contact Fractions A-14
A.2 Chemical Dependent Parameters A-15
A.2.1 Basic Chemical Properties A-15
.1 Molecular Weight A-15
.2 Henry's Law Constant A-15
.3 Soil-Water Partition Coefficient A-l6
.4 Sediment-to-Water Partition Coefficient A-l6
.5 Suspended Sediment-Water Partition Coefficient A-17
.6 Soil and Water Loss Degradation Constants A-l 8
.7 Equilibrium Fraction for Chemical in Soil A-l 8
.8 Equilibrium Fraction for Chemical in Water A-l9
A-i
-------
LIST OF TABLES
A-l Chemical Independent Constants A-1
A-ii
-------
DISTRIBUTION NOTATION
A comprehensive uncertainty analysis was not conducted as part of this study. Initially,
preliminary parameter probability distributions were developed. These are listed in Appendicies A and B.
These were not utilized in the generation of quantative exposure estimates. They are provided as a matter
of interest for the reader.
Unless noted otherwise in the text, distribution notations are presented as follows.
Distribution Description
Log (A,B) Lognormal distribution with mean A and standard deviation B
Log*(A,B) Lognormal distribution, but A and B are mean and standard deviation
of underlying normal distribution.
Norm (A,B) Normal distribution with mean A and standard deviation B
U (A(B) Uniform distribution over the range (A,B)
T (A,B,C) Triangular distribution over the range (A,C) with mode of B
A-iii
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A. EXPOSURE MODEL PARAMETERS
This appendix describes the parameters used in the exposure modeling for the Mercury Study
Report to Congress. For other environmental fate model parameters the reader is referred to Appendicies
A-C of Volume 3.
A.I Chemical Independent Parameters
Chemical independent parameters are variables that remain constant despite the specific
contaminant being evaluated. The chemical independent variables used in this study are described in the
following sections.
A.1.1 Basic Constants
Table A-l lists the chemical independent constants used in the study, their definitions, and values.
Table A-l
Chemical Independent Constants
Parameter Description Value
R ideal gas constant 8.21E-5 m3-atm/mole-K
pa air density 1.19E-3 g/cm3
ua viscosity of air 1.84E-4 g/cm-second
Psed solids density 2.7 kg/L
Cdrag drag coefficient 1.1 E-3
K Von Karman's coefficient 7.40E-1
A: boundary thickness 4.0
A. 1.2 Receptor Parameters
Receptor parameters are variables that reflect information about potential receptors modeled in the
study. These parameters include body weight, exposure duration, and other characteristics of potential
receptors.
A. 1.2.1 Body Weight
Parameter: BWa, BWc
Definition: Body weights (or masses) of individual human receptors
Units: kg
A-l
-------
Receptor Default Value (kg)
Child 17
Adult 70
Technical Basis:
The default values for children and adults are those assumed in U.S. EPA, 1990.
A. 1.2.2 Exposure Duration
Parameter: ED
Definition: Length of time that exposure occurs.
Units: years
Receptor Default Value Distribution Range
(years) (years)
Child
Adult
18
30
U(7,70)
1-18
7-70
Technical Basis:
The 18-year exposure duration for the child is based on U.S. EPA guidance for this study. For
adults, the 30-year duration is the assumed lifetime of the facility (U.S. EPA, 1990). It should be noted for
noncarcinogenic chemicals the exposure duration is not used in the calculations. The range and
distribution are arbitrary to determine the relative sensitivity of this variable, when appropriate.
A. 1.4 Exposure Parameters
Exposure parameters are variables that directly affect an individual's dose or intake of a
contaminant. Such parameters include inhalation and ingestion rates of air, water and crops and the
surface area of skin for the purposes of dermal contact scenarios.
A-2
-------
A. 1.4.1 Inhalation Rate
Parameter: INH
Definition: Rate of inhalation of air containing contaminants.
Units: m3/day
Receptor Default Value Distribution
(mVday)
Infant
Child
Adult
5.14
16
20
7(1.7,5.14,15.4)
1(2.9,16,53.9)
T(6,20,60)
Technical Basis:
The default value for infants is the central value of the distribution used for 1 year olds in Hanford
Environmental Dose Reconstruction Project (HEDR) (1992) and is from Roy and Courtay (1991). The
default value for children.is based on U.S. EPA (1990). The default value for adults is that recommended
in U.S. EPA (1991), which states that this value represents a reasonable upper bound for individuals thai
spend a majority of time at home.
The range for infants is that used for 1 year olds in HEDR (1992) and was determined by scaling
the value 5.14 by 0.3 and 3.0, respectively. The range for children is the smallest range containing the
values used for 5-, 10-, and 15-year-old children in HEDR (1992). The range for the adult was obtained
by scaling the default value by the same numbers used for infants of 0.3 and 3.0 (we note that HEDR,
1992 used a slightly higher central value of 22 m'/day).
To prevent a bias towards upper-end inhalation rates, triangular distributions were considered
more appropriate than more arbitrary uniform distributions, with a most likely value equal to the default
value.
A-3
-------
A. 1.4.2 Consumption Rates
Parameter: CPi, CAj
Definition: Consumption rate of food product per kg of body weight per day.
Units: g dry weight/kg BW/day
Food Type
Leafy Vegetables
Grains and cereals
Legumes
Potatoes
Fruits
Fruiting vegetables
Rooting Vegetables
Beef, excluding liver
Beef liver2
Dairy (milk)
Pork
Poultry
Eggs
Lamba
Child (gDW/kgBW/day)
0.008
3.77
0.666
0.274
0.223
0.120
0.036
0.553
0.025
2.04
0.236
0.214
0.093
0.061
Adult (g DW/kg BW/day)
0.0281
1.87
0.381
0.170
0.570
0.064
0.024
0.341
0.066
0.599
0.169
0.111
0.073
0.057
1 Only the 95-100 percentile of the data from TAS (1991) was nonzero.
Technical Basis:
All of the values reported above are given on a gram dry weight per kg of body weight per day
basis. With the exception of the ingestion rates for adults for leafy vegetables and fruits, the values are
either the 50-55 percentile (or the 95-100 percentile if the median was zero) of the data from Technical
Assessment Systems, Inc. (TAS). The values for the percentiles were reported in g DW/kg of body weight
per day.
TAS conducted this analysis of food consumption habits of the total population and five
population subgroups in the United States. The data used were the results of the Nationwide Food
Consumption Survey (NFCS) of 1987-88 conducted by the United States Department of Agriculture. The
information in the NFCS was collected during home visits by trained interviewers using one-day
interviewer-recorded recall and a two-day self-administered record. A stratified area-probability sample of
households was drawn in the 48 contiguous states from April 1987 to 1988. More than 10,000 individuals
provided information for the basic survey.
A-4
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Each individual's intake of food was averaged across the 3 days of the original NFCS survey, and
food consumption for each food group was determined for each individual. Percentiles were then
computed for six population subgroups:
U.S. population
males > 13 years
females > 13 years
children 1 -6 years
children 7-12 years
infants < 1 year.
The values for children in the previous table are based on the data for children between 7 and 12
year of age, while the adult values are for males older than 12 years of age. The males older than 12 years
of age were chosen to represent the adult since rates for females are lower; this is recoganized to be
somewhat conservative. The United States population rates include the rates of children which were
considered inappropriate for the hypothetical adult receptors modeled in this analysis.
The values for leafy vegetables and fruits for adults are from (USU.S. EPA 1989).
A.I.4.3 Soil Ingestion Rate
Parameter: Cs
Definition: Amount of soil ingested daily.
Units: g/day
Receptor
Pica Child
Child
Adult
Default Value (g/day)
7.5
0.2
0.1
Distribution
U(5,10)
U(0.01 6,0.2)
Uf 0.0 16,0.1)
Range (g/day)
5-10
0.016-0.2
0.016-0.1
Technical Basis:
Soil ingestion may occur inadvertently through hand-to-mouth contact or intentionally in the case
of a child who engages in pica. The default values for adults and non-pica children are those suggested for
use in U.S. EPA (1989). More recent studies have found that these values are rather conservative. For
example, Calabrese and Stanek (1991) found that average soil intake by children was found to range from
0.016 to 0.055 g/day. This range, in conjunction with the suggested U.S. EPA values, was used to obtain
the ranges shown.
Several studies suggest that a pica child may ingest up to 5 to 10 g/day (LaGoy, 1987, U.S. EPA,
1989). This range was selected, and the midpoint was chosen as the default value.
A-5
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A. 1.4.4 Groundwater Ingestion Rate
Parameter: Cw
Definition: The amount of water consumed each day.
Units: L/day
Receptor Default Values Distribution
(L/day)
Child
Adult
1.0
2.0
Log*(0.378; 0.079)
Log*(0.1; 0.007)
Technical Basis:
The default values for children and adult are those also suggested in U.S. EPA (1989) and were
first published by the Safe Drinking Water Committee of the National Academy of Sciences (NAS, 1977).
The distributions are those computed in Roseberry and Burmaster (1992). In that paper,
lognormal distributions were fit to data collected in a national survey for both total water intake and tap
water intake by children and adults. These data were originally gathered in the 1977-1978 Nationwide
Food Consumption Survey of the United States Department of Agriculture and were analyzed by Ershow
and Cantor (1989).
In Roseberry and Burmaster (1992), distributions were fit to the intake rates for humans ages 0-1
year, 1-11 years, 11-20 years, 20-65 years and older than 65 years. The distribution for children ages 1-11
was chosen for the child's distribution given in the previous table and the distribution for adults ages 20-65
was used for the adult. For the purpose of the present analysis, the tap water intake was deemed more
appropriate than total water intake. The total water intake included water intrinsic in foods that are
accounted for in the agricultural pathways, while the tap water intake was the sum of water consumed
directly as a beverage and water added to foods and beverages during preparation.
The minima and maxima were selected as the 2.5 and 97.5 percentiles, respectively.
A-6
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A. 1.4.5 Fish Ingestion Rate
Parameter: Cf
Definition: Quantity of locally - caught fish ingested per day.
Units: g/day
Receptor Default Value (g/day)
High End Fisher 60
Child of high end fisher 20
Recreational Angler 30
Technical Basis:
Because of the bioaccumulation of methylmercury in fish, the fish ingestion rate is an important
parameter for modeling mercury exposure. Fish consumption rates are difficult to determine for a general
population study because individual fish ingestion rates vary widely across the United States. This animal
protein source may be readily consumed or avoided on a seasonal, social, economic or demographic basis.
Ideally, for an actual site, specific surveys identifying the type, source, and quantity of fish consumed by
area residents would be used. Within the context of this study, it is not possible to characterize this
variability completely.
For this part of the assessment, individuals in three broad groups of exposed populations will be
considered: high end fishers, recreational anglers and the general population. For the general population,
no commercial distribution of locally caught fish was assumed. All consumers of locally-caught fish were
assumed to be recreational anglers or subsistence fishers.
In U.S. EPA's 1989 Exposure Factors Handbook, fish consumption data from Puffer (1981) and
Pierce et al. (1981) are suggested as most appropriate for fish consumption of recreational anglers from
large water bodies. The median of this subpopulation is 30 g/day with a 90th percentile of 140 g/day (340
meals/year). The median was used as the surrogate value for recreational anglers.
For subsistence fishers, human fish consumption data were obtained from the report of the
Columbia River Inter-Tribal Fish Commission (1994), which estimated fish consumption rates for
members of four tribes inhabiting the Columbia River Basin. The estimated fish consumption rates were
based on interviews with 513 adult tribe members who lived on or near the reservation. The participants
had been selected from patient registration lists provided by the Indian Health Service. Adults interviewed
provided information on fish consumption for themselves and for 204 children under 5 years of age.
During the study fish were consumed by over 90% of the population with only 9% of the
respondents reporting no fish consumption. Monthly variations in consumption rates were reported. The
average daily consumption rate during the two highest intake months was 107.8 grams/day, and the daily
consumption rate during the two lowest consumption months was 30.7 grams/day. Members who were
aged 60 years and older had an average daily consumption rate of 74.4 grams/day. During the past two
decades, a decrease in fish consumption was generally noted among respondents in this survey. The
maximum daily consumption rate for fish reported for this group was 972 grams/day.
A-7
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The mean daily fish consumption rate for the total adult population (aged 18 years and older) was
reported to be 59 grams/day. The mean daily fish consumption rate for the adult females surveyed was 56
g/day and the mean daily fish consumption rate for the adult males surveyed was 63 grams. A value of 60
grams of fish per day was selected for the subsistence angler modeled in this report.
Other fish consumption rate studies for specific subpopulations (i.e., anglers and subsistence
consumers) have been conducted. These studies are briefly described in Volume IV. These studies
demonstrate the wide range offish consumption rates exhibited across the U.S. population. They also tend
to corroborate the estimates to be used in this analysis. These analyses also illustrate the difficulty in
determining average and high-end consumption rates for subpopulations considered to be more likely to
consume more fish.
In the lacustrine scenarios of this assessment, all fish were assumed to originate from the lakes,
which are considered to represent several small lakes that may be present in a hypothetical location.
The effects of fish preparation for food on extant mercury levels in fish have also been evaluated
(Morgan et al., 1994). Total mercury levels in walleye were found to be constant before and after
preparation; however, mercury concentrations in the cooked fish were increased 1.3 to 2.0 times when
compared to mercury levels in the raw fish. It was suggested that this increase was probably due to water
and fat loss during cooking and fish skin removal. A preparation factor adjustment was noted but not
implemented in this analysis because human consumption levels were measured on uncooked fish. For
more information see Volume IV.
A-8
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A. 1.4.6 Contact Fractions
Parameter: FPi, Faj
Definition: that fraction of the food type grown or raised on contaminated land
Units: Unitless
Food
Subsistence
Farmer
Rural Home Urban Gardener
Gardener/
Subsistence Fisher
Comment
Grains
Legumes
Potatoes
Root Vegetables
Fruits
0.667
0.8
0.225
0.268
0.233
0.195 Values are for com from
Table 2-7 in U.S. EPA
(1989)
0.5 Values are for peas from
Table 2-7 in U.S. EPA
(1989).
0.031 Values are for total fresh
potatoes from Table 2-7 in
U.S. EPA (1989).
0.073 Values are for carrots from
Table 2-7 in U.S. EPA
(1989).
Values are for Total non-
0.076 citrus fruit from Table 2-7
in U.S. EPA (1989).
Fruiting 1
Vegetables
Leafy Vegetables 1
Beef 1
Beef liver 1
Dairy 1
Pork 1
Poultry 1
Eggs 1
Lamb 1
0.623
0.058
0
0
0
0
0
0
0
0.317
0.026
0
0
0
0
0
0
0
Values are for tomatoes
from Table 2-7 in U.S. EPA
(1989).
Values are for lettuce from
U.S. EPA (1989).
Technical Basis:
The values for the subsistence farmer are consistent with the assumptions regarding this scenario.
The values for the gardeners are from U.S. EPA (1989), per U.S. EPA guidance. Because it is assumed
that only the subsistence farmers will consume contaminated animal products, the contact fractions for
gardeners is 0 for consumption of local animal products.
A-9
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A.2 Chemical Dependent Parameters
Chemical dependent parameters are variables that change depending on the specific contaminant
being evaluated. The chemical dependent variables used in this study are described in the following
sections.
A.2.1 Basic Chemical Properties
The following sections list the chemical properties used in the study, their definitions, and values.
A.2.1.1 Molecular Weight
Parameter: Mw
Definition: The mass in grams of one mole of molecules of a compound.
Units: g/mole
Chemical
Default Value (g/mole)
Hg°, Hg2+
Methylmercury
Methyl mercuric chloride
Mercuric chloride
201
216
251
272
A.2.1.2 Henry's Law Constant
Parameter: H
Definition: Provides a measure of the extent of chemical partitioning between air and water at
equilibrium.
Units:
atm-mVmole
Chemical
Default Value (atm-m3/mole)
Hg°
Hg2+ (HgCl2)
Methylmercury
V.lxlO-3
7.1xlO'10
4.7x10'"
Technical Basis:
The higher the Henry's Law Constant, the more likely a chemical is to volatilize than to remain in
the water. The value for Hg° is from Iverfeldt and Persson (1985), while the other values are from
Lindquist and Rodhe (1985).
A-10
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Concentrations in Crops and Corresponding Soils in the Netherlands. J. Agric. Food Chem.,
34:1067-1074.
Wilken, R.D. and H. Hintelmann (1991). Mercury and Methylmercury in Sediments and Suspended
Particles from the River Elbe, North Germany. Water, Air, and Soil Poll. 56: 427-437.
A-16
-------
APPENDIX B
ESTIMATED NATIONAL AND REGIONAL POPULATIONS OF WOMEN OF
CHILD-BEARING AGE: UNITED STATES, 1990
-------
Estimated National and Regional Populations of
Women of Child-Bearing Age: United States, 1990
Because methylmercury is a developmental toxin, the subpopulation judged of particular concern
in this Mercury Study: Report to Congress was women of child-bearing age. Estimates of the size of the
population of women of reproductive age, number of live births, number of fetal deaths, and number of
legal abortions can be used to predict the percent of the population and number of women of reproductive
age who are pregnant in a given year. This methodology has been previously used in the Agency for
Toxic Substances and Disease Registry's (ATSDR's) Report to Congress on The Nature and Extent of
Lead Poisoning in Children in the United States (Mushak and Crocetti, 1990).
The estimates of number of women of child-bearing age calculated for this Mercury Study:
Report to Congress were prepared by Dr. A.M. Crocetti under purchase order from the EPA Office of Air
Quality, Planning and Standards (OAQPS). The techniques used by Dr. Crocetti parallel those used to
prepared the 1984 estimates for ATSDR. To estimate the size of this population on a national basis Vital
and Health Statistics data for number of live births (National Center for Health Statistics of the United
States, 1990; Volume I, Natality, Table 1-60, pages 134-140), and fetal deaths (National Center for Heal*
Statistics of the United States, 1990; Volume II, Mortality; Table 3-10, pages 16, 18, and 20). Fetal
wastage, that is, spontaneous abortions prior to 20 weeks of gestation were not considered since no
systematically collected, nationally based data exist.
The estimate of number of women of child-bearing age includes some proportion of women who
will never experience pregnancy. However, substitution of the number of pregnancies in a given year
provides some measure of assessing the size of the surrogate population at risk. Estimates of the size of
the population were based on "Estimates of Resident Population of the United States Regions and
Divisions by Age and Sex" (Byerly, 1993). The Census data for 1990 were grouped by age and gender.
The sizes of these populations are shown in Table B-l.
Women ages 15 through 44 are the age group of greatest interest in identifying a subpopufation of
concern for the effects of a developmental toxin such as methylmercury. This population consisted of
58,222,000 women living within the contiguous United States. This population was chosen rather than for
the total United States (population 58,620,000 women ages 15 through 44 years) because the dietary
survey information from CSFII 89-91 did not include Hawaii and Alaska. Based on estimates offish
consumption data for Alaska by Nobmann et al. (1992) the quantities of fish eaten by Alaskans exceeds
those of the contiguous U.S. population. It is also estimated that residents of the Hawaiian Islands also
have fish consumption patterns that differ from those of the contiguous United States.
The number of pregnancies per year was estimated by combining the number of live births,
number of fetal deaths (past 20 weeks of gestation) and the number of legal abortions. The legal abortion
data were based on information published by Koonin et al. (1993) in Morbidity and Mortality Weekly
Report. These totals are presented in Table B-2. As noted in this table, the total of legal abortions
includes those with unknown age which were not included in the body of each table entry. There were
2,929 such cases for the United States in 1990 or 0.2% of all legal abortions. Another complication in the
legal abortion data was for the age group 45 and older. The available data provide abortion data for 40
years and older only. To estimate the size of the population older than 45 years, the number of legal
abortions for women age 40 years and older were allocated by using the proportions of Live Births and
Fetal Deaths for the two age groups 40-44 and 45 and older.
B-l
-------
It was estimated that within the contiguous United States 9.5% of women ages 15 to 44 years were
pregnant in a given year. The total number of live births reported in 1990 for this age group was
4,112,579 with 30,974 reported fetal deaths and 1,407,830 reported legal abortions. The estimated
number of total pregnancies for women ages 15 to 44 years was 5,551,383 in a population of 58,222,000
women.
REFERENCES
Byerly, E.R. (1993) State Population Estimates by Age and Sex: 1980-1992, U.S. Bureau of the Census,
Current Population Reports P25-1106, U.S. Government Printing Office, Washington, DC.
Koonin, L.M., Smith, J.C., and Ramick, M. (1993) Division of Reproductive Health, National Center for
Chronic Disease Prevention and Health Promotion: Abortion Surveillance - United States, 1990:
Morbidity Mortality Weekly Report, Vol 42/No. SS-6, pps. 29-57, December 17.
Mushak, P., and Crocetti, A.M. (1988). The Nature and Extent of Lead Poisoning in Children in the
United States: A Report to Congress. Agency for Toxic Substances and Disease Registry, United States
Public Health Service, United States Department of Health and Human Services.
National Center for Health Statistics of the United States (1990) Volume I. Natality: Table 1-60; pages
134-140.
National Center for Health Statistics of the United States (1990) Volume II. Mortality; Table 3-10, pages
16, 18, and 20.
Nobmann, E.D., Byers, T., Lanier, A.P., Hankin, J.H., and Jackson, M.Y. (1992) The diet of Alaska
Native adults: 1987-1988. Amer. J. Clin. Nutr. 55: 1024-1032.
B-2
-------
Table B-l
Resident Population of the United States and Divisions, April 1,1990
Census by Gender and Age; in Thousands, including Armed Forces Residing in Region
Resident Population of the United States and Divisions, April 1, 1990 Census by Gender and
Age; in Thousands, including Armed Forces Residing in Region.
Division/
Gender
United States
Male
Female
% Female
Total
248,710
121,239
127,471
51.3
< 15 Years
of Age
53,853
27,570
26,284
48.8
15-44 Years
of Age
117,610
58,989
58,620
49.8
> 44 Years
of Age
77,248
34,680
42,567
55.1
Resident Population of the United States and Divisions, April 1, 1990 Census by Gender and
Age; in Thousands, including Armed Forces Residing in Region.
Division/
Gender
Contiguous
United States
Male
Female
% Female
Total
247,052
120.385
126,667
51.3
< 15 Years
of Age
53,462
27,369
26,094
48.8
15-44 Years
of Age
116,772
58.548
58,222
49.9
> 44 Years
of Age
76,817
34,467
42.348
55.1
Resident Population of the United States and Divisions, April 1, 1990 Census by Gender and
Age; in Thousands, including Armed Forces Residing in Region.
Division/
Gender
New England
Male
Female
% Female
Total
13,207
6,380
6,827
51.7
< 15 Years
of Age
2,590
1,327
1,264
48.8
15-44 Years
of Age
6.379
3,174
3,202
50.2
> 44 Years
of Age
4,239
1,878
2,361
55.7
B-3
-------
Table B-l (continued)
Resident Population of the United States and Divisions, April 1, 1990 Census by Gender and
Age; in Thousands, including Armed Forces Residing in Region.
Division/
Gender
Middle
Atlantic
States
Male
Female
% Female
Total
37,602
18,056
19,547
52
< 15 Years
of Age
7,471
3,824
3,645
49
15-44 Years
of Age
17,495
8,676
8,818
50
> 45 Years
of Age
12,638
5,554
7,083
56
Resident Population of the United States and Divisions, April 1, 1990 Census by Gender and
Age; in Thousands, including Armed Forces Residing in Region.
Division/
Gender
E North Central
Male
Female
% Female
Total
42,009
20,373
21,636
51.5
< 15 Years
of Age
9,233
4.728
4,505
48.8
15-44 Years
of Age
19,596
9,744
9,851
50.3
> 44 Years
of Age
13,180
5,899
7,279
55.2
Resident Population of the United States and Divisions, April 1, 1990 Census by Gender and
Age; in Thousands, including Armed Forces Residing in Region.
Division/
Gender
West North
Central
Male
Female
% Female
Total
17,660
8,599
9,061
51.3
< 15 Years
of Age
3,967
2,032
1,935
48.8
15-44 Years
of Age
8,017
4,020
3,997
49.9
> 44 Years
of Age
5,676
2,546
3,129
55.1
B-4
-------
Table B-l (continued)
Resident Population of the United States and Divisions, April 1, 1990 Census by Gender and
Age; in Thousands, including Armed Forces Residing in Region.
Division/
Gender
South
Atlantic
Male
Female
% Female
Total
43,567
21,129
22,438
51.5
< 15 Years
of Age
8,864
4,531
4,333
48.9
15-44 Years
of Age
20,579
10,279
10,301
50.1
> 44 Years
of Age
14,122
6,321
7,804
55.3
Resident Population of the United States and Divisions, April 1, 1990 Census by Gender and
Age; in Thousands, including Armed Forces Residing in Region.
Division/
Gender
East South
Centra]
Male
Female
% Female
Total
15,176
7,301
7,875
51.9
< 15 Years
of Age
3,316
1,698
1,618
48.8
15-44 Years
of Age
7,037
3,472
3,565
50.7
> 44 Years
of Age
4,823
2,132
2,692
55.8
Resident Population of the United States and Divisions, April 1, 1990 Census by Gender and
Age; in Thousands, including Armed Forces Residing in Region.
Division/
Gender
West South
Central
Male
Female
% Female
Total
26,703
13,061
13,641
51.1
< 15 Years
of Age
6,366
3,256
3,110
48.9
15-44 Years
of Age
12,687
6,359
6,328
49.9
> 44 Years
of Age
7,651
3,445
4,204
54.9
B-5
-------
Table B-l (continued)
Resident Population of the United States and Divisions, April 1, 1990 Census by Gender and
Age; in Thousands, including Armed Forces Residing in Region.
Division/
Gender
Mountain
States
Male
Female
% Female
Total
13,659
6,779
6,880
50.4
< 15 Years
of Age
3,313
1,696
1,616
48.8
15-44 Years
of Age
6,435
3,259
3,176
49.4
> 44 Years
of Age
3,910
1,825
2,087
53.4
Resident Population of the United States and Divisions, April 1, 1990 Census by Gender and
Age; in Thousands, including Armed Forces Residing in Region.
Division/
Gender
West North
Central
Male
Female
% Female
Total
17,660
8,599
9,061
51.3
< 15 Years
of Age
3,967
2,032
1,935
48.8
15-44 Years
of Age
8,017
4,020
3,997
49.9
> 44 Years
of Age
5,676
2,546
3,129
55.1
Resident Population of the United States and Divisions, April 1, 1990 Census by Gender and
Age; in Thousands, including Armed Forces Residing in Region.
Division/
Gender
Pacific (5 States
including Alaska
and Hawaii)
Male
Female
% Female
Total
39,127
19,562
19,565
50.0
< 15 Years
of Age
8,734
4,476
4,258
48.8
15-44 Years
of Age
19,394
10,004
9,379
48.4
> 44 Years
of Age
11,011
5,083
5,929
53.8
B-6
-------
Table B-l (continued)
Resident Population of the United States and Divisions, April 1, 1990 Census by Gender and
Age; in Thousands, including Armed Forces Residing in Region.
Division/
Gender
Pacific
(Washington,
Oregon and
California only)
Male
Female
% Female
Total
37,469
18,708
18,761
50.1
< 15 Years
of Age
8,343
4,275
4,068
48.8
15-44 Years
of Age
18,546
9,563
8,981
48.4
> 44 Years
of Age
10,580
4,870
5,710 .
54.0
B-7
-------
Table B-2
Pregnancies by Outcome for Resident Females by Divisions and States,
U.S. 1990, by Age
Pregnancies by Outcome for Resident Females by Divisions and States, U.S. 1990, by Age*
United
States
Females
Live births
Fetal Deaths
Legal Abortions
Total
Pregnancies
% Pregnant
Total**
127,471,000
4,158,212
31,386
1,429,577
5,619,175
< 15 Years
26,284,000
11,657
174
11,819
23,650
-
15-44 Years
58,620,000
4,144,917
31,176
1,413,992
5,590,085
9.5
>44
Years***
42,567,000
1,638
36
837
2,511
-
Pregnancies by Outcome for Resident Females by Divisions and States, U.S. 1990, by Age*
Contiguous
United
States
Females
Live births
Fetal Deaths
Legal Abortions
Total
Pregnancies
% Pregnant
Total**
126,667,000
4,125,821
31,183
1,423,340
5,580,344
-
< 15 Years
26,094.000
11,615
173
11,765
23,553
-
15-44 Years
58,222,000
4,112,579
30,974
1,407,830
5,551,383
9.5
> 44 Years
42,348,000
1.627
36
833
2.496
-
Pregnancies by Outcome for Resident Females by Divisions and States, U.S. 1990, by Age*
New
England
Females
Live births
Fetal Deaths
Legal Abortions
Total
Pregnancies
% Pregnant
Total**
6,827,000
201,173
1,226
78,347
280,746
-
< 15 Years
1,264,000
270
4
487
761
-
15-44 Years
3,202,000
200,827
1,220
77,358
279,405
8.7
>44 Years
2,361,000
76
2
37
115
-
B-8
-------
Table B-2 (continued)
Pregnancies by Outcome for Resident Females by Divisions and States, U.S. 1990, by Age*
Middle
Atlantic
Females
Live births
Fetal Deaths
Legal Abortions
Total
Pregnancies
% Pregnant
Total**
19,547,000
591,826
5,653
252,599
850,078
< 15 Years
3,645,000
1,305
25
1,912
3,242
15-44 Years
8,818,000
590,238
5,622
250,484
846,344
9.6
> 44 Years
7,083,000
283
6
157
446
Pregnancies by Outcome for Resident Females by Divisions and States, U.S. 1990, by Age*
East
North
Central
Females
Live births
Fetal Deaths
Legal Abortions
Total
Pregnancies
% Pregnant
Total**
21,636,000
675,512
4.555
166,897
846,964
< 15 Years
4,505,000
1.838
14
1,056
2,908
15-44 Years
9,851,000
673,449
4,537
165,434
843,420
8.6
> 44 Years
7,279,000
225
4
109
338
Pregnancies by Outcome for Resident Females by Divisions and States, U.S. 1990, by Age*
West
North
Central
Females
Live births
Fetal Deaths
Legal Abortions
Total
Pregnancies
% Pregnant
Total**
9,061,000
270,331
1,741
57,219
329,291
< 15 Years
1,935,000
457
6
398
861
-
15-44 Years
3,997,000
269,792
1,733
56,562
328,087
8.2
> 44 Years
3,129,000
82
2
30
114
-
B-9
-------
Table B-2 (continued)
Pregnancies by Outcome for Resident Females by Divisions and States, U.S. 1990, by Age*
South
Atlantic
Females
Live births
Fetal Deaths
Legal Abortions
Total
Pregnancies
% Pregnant
Total**
22,438,000
700,285
6,453
238,538
945,276
< 15 Years
4,333,000
2,644
57
2,242
4,943
-
15-44 Years
10,301,000
697,424
6,389
235,536
939,349
9.1
> 44 Years
7,804,000
217
7
123
347
-
Pregnancies by Outcome for Resident Females by Divisions and States, U.S. 1990, by Age*
East
South
Central
Females
Live births
Fetal Deaths
Legal Abortions
Total
Pregnancies
% Pregnant
Total**
7,875,000
236,374
2,954
53,919
292,347
< 15 Years
1,618,000
1,143
25
662
1,830
-
15-44 Years
3,565,000
235,195
2,027
53,030
290,252
8.1
> 44 Years
2,692,000
36
2
19
57
-
Pregnancies by Outcome for Resident Females by Divisions and States, U.S. 1990, by Age*
West
South
Central
Females
Live births
Fetal Deaths
Legal Abortions
Total
Pregnancies
% Pregnant
Total**
13,641,000
472,721
3,258
122,261
598,240
< 15 Years
3,110,000
1,852
21
781
2,654
-
15-44 Years
6,328,000
470,715
3,234
121,100
595,049
9.4
> 44 Years
4,204,000
154
3
90
247
-
B-10
-------
Table B-2 (continued)
Pregnancies by Outcome for Resident Females by Divisions and States, U.S. 1990, by Age*
Mountain
Females
Live births
Fetal Deaths
Legal Abortions
Total
Pregnancies
% Pregnant
Total**
6,880,000
242,829
1,492
50,880
295,201
< 15 Years
1,616,000
500
6
288
794
-
15-44 Years
3,176,000
242,235
1,483
50,330
294,048
9.3
> 44 Years
2,087,000
94
3
31
128
-
Pregnancies by Outcome for Resident Females by Divisions and States, U.S. 1990, by Age*
Pacific
(5 states
including
Alaska and
Hawaii)
Females
Live births
Fetal Deaths
Legal Abortions
Total
Pregnancies
% Pregnant
Total**
19,565.000
767.161
4.954
408,917
1,181,032
< 15 Years
4.258.000
1,648
16
3.993
5,657
-
15-44 Years
9.379,000
765.042
4.931
404.158
1,174.131
12.5
> 44 Years
5,929,000
471
7
241
719
-
Pregnancies by Outcome for Resident Females by Divisions and States, U.S. 1990, by Age*
Pacific
(Washington,
Oregon, and
California)
Females
Live births
Fetal Deaths
Legal
Abortions
Total
Pregnancies
% Pregnant
Total**
18,761.000
734,770
4.751
402,680
1,142,201
-
< 15 Years
4.068,000
1,606
15
3,939
5,560
-
15-44 Years
8.981,000
732.704
4.729
397,996
1,135,429
12.6
> 44 Years
5,710.000
460
7
237
704
-
B-ll
-------
APPENDIX C
ANALYSIS OF MERCURY LEVELS IN FISH AND SHELLFISH
REPORTED IN NATIONAL MARINE FISHERIES SERVICE
SURVEY OF TRACE ELEMENTS IN THE FISHERY RESERVE
-------
C.I Introduction
Some reviewers of data on the levels of mercury in fish and shellfish have expressed concern
about the methods used to handle "nondetects" by the investigators who originally reported the data on
the concentrations of mercury in fish and shellfish tissues. Specifically, these reviewers have expressed
concern about the potential impact that different methods of handling nondetects may have on the
reported mean concentrations of mercury. The purpose of this memo is to report the results of a data
analysis performed on the nondetects in the mercury data reported in the report National Marine
Fisheries Service Survey of Trace Elements in the Fishery Reserve, hereinafter referenced as the NMFS
Report.
The major conclusion of this analysis is that different methods of handling nondetects have
negligible impact on the reported mean concentrations. This conclusion follows from two findings from
the data analysis, set forth below. First, when mean mercury levels are relatively "large", there are few,
if any, nondetects, so the methodology employed to handle nondetects is irrelevant. Second, when mean
mercury levels are small, there are relatively large numbers of nondetects. However, the differences
between different methods of handling nondetects result in small differences in the resultant mean
values.
The NMFS Report reports number of samples, number of nondetects, and mean, standard
deviation, minimum and maximum mercury level in ppm for 1,333 combinations of fish/shellfish species,
variety, location caught, and tissue. Of these, 777 correspond to fish/shellfish species for which we have
mercury concentration data. These 777 combinations form the basis for the analyses reported in this
memorandum. They represent 5,707 analyses of fish and shellfish tissues for mercury, of which 1,467, or
26 percent, are reported as nondetects. Because the mercury concentration data is used in our analyses at
the species level, not at the more detailed species/variety/location/tissue level, we have aggregated, or
pooled, the 777 combinations to 35 different species for the purposes of this analysis.
In the following sections, we first discuss various methods of handling nondetects in calculating
mean mercury concentrations, then the analysis method adopted, and finally the results of that analysis.
C.2 Methods for Handling the Detection Limits
There are five methods commonly used to handle values below the detection limits in calculating
the mean mercury levels.
1. All nondetects are treated as being equal to 0. The total number of samples for which
mercury was measured is used in the mean calculation and it is assumed that the
concentration of mercury is 0.000 whenever the chemical analysis was reported as
"not detected". This approach may lead to an underestimation of the true mean,
2. All nondetects are excluded from the calculation of the mean. The mean is calculated
as if these samples were not selected. The number of nondetects is subtracted from
the total number of samples for which mercury was measured, and the resulting
number is used to calculate the mean. This method may overestimate the true mean
C-l
-------
and always yields a mean estimate greater than that obtained by method 1 (see
formulae in Addendum A).
3. All nondetects are replaced with a fixed value, usually one-half of the detection limit.
This method is the most widely used and accepted of the five methods. It is difficult
to know whether this method will lead to an underestimation or to an overestimation
of the true mean. But it will always lead to an estimate that falls between the
estimates obtained from method 1 and method 2.
4. All nondetects are replaced with simulated mercury levels randomly selected in the
interval (0, detection limit) according to an appropriate statistical distribution. This
method is close in spirit to method 3 and, like method 3, will lead to an estimate
falling between estimates obtained from method 1 and method 2.
5. All nondetects are replaced with the detection limit. This method may overestimate
the mean as all nondetects are smaller or equal to the detection limit. The mean
calculated by method 5 will also be between the means obtained from method 1 and
method 2.
The NMFS Report says that method 2 - nondetects dropped from the calculation - was used to
calculate their reported mean mercury levels. However, an examination of their data indicates that the
investigators did not always use method 2. It appears that other methods, including method 1 -
nondetects set equal to zero may have sometimes been used.
C.3 Method of Analysis
The approach adopted amounts to comparing means obtained by two different methods. Since we
do not have access to the raw data, it was necessary to first assume that the reported mean mercury levels
were calculated by one of the five methods mentioned above. Then we calculated the mean that would
have been obtained if another method had been used.
Although it is possible to consider all ten possible combinations of two methods that can be
obtained from the five under analysis, we have confined ourselves to the case where the other methods
are compared with method 3, the latter being the most commonly used in such situations. The following
three scenarios are studied:
The reported means are assumed to have been calculated by method 1. The
corresponding mean mercury levels that would have been obtained by method 3 were
then calculated. The two sets of corresponding means are then compared. The
calculation method is reported in Addendum A.
The above analysis was repeated for method 2 and method 3.
The above analysis was repeated for method 5 and method 3. It should be noted that
if the reported mean is 0 and is assumed to be obtained by method 5 then method 3
might yield a negative value. In that case the mean was set to 0.000.
C-2
-------
It is unlikely that method 4 was used to calculate the reported means since this would likely have
appeared in the NMFS report. Therefore method 4 is ruled out of this analysis. To be able to calculate
the mean mercury level by method 3, a value for the limit of detection is needed. We have been told that
the limit of detection was 0.100 ppm. However, the data reported in the NMFS Report have numerous
reported positive values less than 0.100 ppm. We therefore used the lowest of all detected analytical
values as the presumed limit of detection. This value is 0.010 ppm.
Addendum B lists and graphs the mean mercury levels in ppm by fish and shellfish species, as
reported by NMFS, then as calculated according to the methodology described above. That is, the mean
mercury level that would be obtained by method 3, assuming NMFS used method 1 is presented,
followed by the other two comparisons listed above. Then the mean differences between pairs of
methods are presented.
C.4 Data Analysis Results
The calculations comparing method 1 nondetects dropped and method 3 nondetects set to
one-half the detection limit, viz., 0.005 - are reported in Figure C-la and C-lb. The straight line in
Figure C- la is the line y = x; points on the line correspond to mean values that are the same for both
methods. All points are on the line y = x, or nearly on it; the two methods yield identical results for most
species. This result follows from the fact that when mean mercury levels are relatively large, very few
nondetects were reported (see Figure C-4a).
In order to have a better assessment of the magnitude of the differences between method 1 and
method 3. we plotted the differences between the two methods versus method 1 in Figure C-lb. The
differences between methods 1 and 3 are never as high as 0.004 ppm. Further, they never exceed 0.001
ppm when the mean is above 0.200 ppm.
C-3
-------
Difference between Method 3 and
Method 1, ppm
6 op
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Mean Mercury Levels by
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The results comparing methods 2 and 3 are in Figures D-2a and D-2b. They lead to the same
conclusions as the comparison of methods 1 and 3. The differences between methods 2 and 3 never
exceed 0.030 ppm in magnitude. Because the differences between methods 2 and 3 are an order of
magnitude greater than the other two comparisons, it was decided to investigate the larger differences
between these methods to see if there were any significant patterns.
The results comparing methods 5 and 3 are in Figures D-3a and D-3b. They lead to the same
conclusions as the two previous comparisons. The differences between methods 5 and 3 never exceed
0.003 ppm in magnitude. They never exceed 0.001 ppm when the mean mercury level is above 0.200
ppm.
These results follow from the fact that the number of nondetects is especially high when the
reported mean is very small. When that mean is larger, there are very few nondetects, so that all methods
yield virtually the same results. This phenomenon is well illustrated in Figures D-4a and D-4b, which
present the number and percentage of nondetects against the mean mercury levels, respectively.
C-5
-------
o
Difference between Method 3 and
Method 2, ppm
666
Mean of Mercury Levels by Method
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n
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Percent of Nondetects
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-------
ADDENDUM A
This addendum provides the formulae used to calculate the mean Mercury levels according
to the four methods used in the analysis.
Let W0 be the total number of samples for which the fish was measured, A^the total
number of samples in which no Mercury was detected and */0the limit of detection. Suppose that
jc, stands for the Mercury level (ppm) detected in the /sample and that Xi,X2,Xi and Xs are the
mean Mercury levels calculated by methods 1,2,3 and 5 respectively. Then we have that,
X i = - > x. ; , X 2 =
Let Xs/i, X3/2 and X^/5 be the means calculated by method 3 under the assumption that
the reported data are calculated by method 1, 2 and 5 respectively. These conditional means are obtained
as follows:
and
C-9
-------
ADDENDUM B
Mercury Levels by Species
NMFS Data:
Table and Graphs
Comparisons of Different Methods of Handling Nondetects:
Table and Graphs
C-10
-------
Table C-l
Records in NMFS Report for which the difference between Method 3 and Method 2 is greater than
0.010 (sorted according to the magnitude of the difference, DIFF)
SPECIES
Herring
Sole
Tuna
Squid
Cod
Crab
Squid
Shrimp
Cod
Shrimp
Cod
Clam
Mullet
Salmon
Crab
Mullet
Oyster
Scallop
Clam
Squid
Shrimp
Oyster
Squid
Squid
Tuna
Clam
Croaker
Pollock
Squid
Shrimp
Salmon
Mackerel
Trout (Sea)
Clam
Flounder
Mullet
Shrimp
Squid
Cod
Pollock
VARIETY
Pacific
Petrale
Bigeye
All. Longfinned
Atlantic
Tanner (Bairdi)
Atl. Longfinned
Alaska (Sidestriped)
Atlantic
Ocean
Atlantic
Butter
Striped
Coho (Silver)
Tanner (Bairdi)
Striped
Pacific (Giant)
Calico
Hard
Shortfinned
Brown
Pacific (Giant)
Atl. Longfinned
Shortfinned
Yellowfin
Razor
Atlantic
Walleye (Alaska)
Shortfinned
Pink
Coho (Silver)
Jack
Silver (White)
Soft
Fourspot
Striped
White
Shortfinned
Atlantic
LOCATION
Pacific NWest
Pacific NWest
Hawaii
N. Atlantic
N. Atlantic
Alaska
N. Atlantic
Alaska
N. Atlantic
Pacific NWest
N. Atlantic
Pacific NWest
Hawaii
Alaska
Alaska
South Atlantic
California
S. Atlantic
N. Atlantic
N. Atlantic
Gulf
California
N. Atlantic
N. Atlantic
Hawaii
Alaska
Gulf
Alaska
N. Atlantic
Gulf
Pacific NWest
California
Gulf
N. Atlantic
N. Atlantic
Gulf
Gulf
N. Atlantic
N. Atlantic
N. Atlantic
TISSUE
whole
muscle
liver
mantle, skinless
liver
meat
mantle, skinless
tail, peeled
liver
tail, peeled
liver
shucked, large
muscle
muscle
meat
muscle
shucked
abductor muscle
shucked, cherrysto
mantle, skinless
tail, peeled
shucked
mantle, skinless
mantle, skinless
liver
shucked
muscle
muscle
mantle, skinless
tail, peeled
liver
headed
muscle
shucked
muscle
muscle
tail, peeled
mantle, skinless
muscle
liver
NO.
20
11
2
6
2
10
7
7
6
10
4
10
18
10
10
19
10
10
10
4
10
20
20
2
2
11
9
28
11
20
2
4
10
19
3
12
10
5
16
3
N. DET
19
6
1
5
1
5
5
4
5
6
2
8
16
7
5
15
8
8
5
2
8
12
13
1
1
8
6
12
6
10
1
3
5
11
1
10
8
4
6
2
MEAN
.260
.347
.250
.130
.210
.208
.140
.168
.110
.136
.158
.100
.090
.110
.152
.098
.090
.090
.141
.135
.085
.111
.100
.120
.120
.083
.090
.135
.105
.114
.110
.070
.100
.086
.145
.060
.060
.060
.121
.070
DIFF
-0.242
-0.187
-0.123
-0.104
-0.103
-0.102
-0.096
-0.093
-0.088
-0.079
-0.077
-0.076
-0.076
-0.074
-0.074
-0.073
-0.068
-0.068
-0.068
-0.065
-0.064
-0.064
-0.062
-0.058
-0.058
-0.057
-0.057
-0.056
-0.055
-0.055
-0.053
-0.049
-0.048
-0.047
-0.047
-0.046
-0.044
-0.044
-0.044
-0.043
C-I1
-------
Table C-l (continued)
Records in NMFS Report for which the difference between Method 3 and Method 2 is greater than
0.010 (sorted according to the magnitude of the difference, DIFF)
Flounder
Mackerel
Flounder
Tuna
Herring
Scallop
Squid
Mullet
Shrimp
Flounder
Squid
Oyster
Flounder
Salmon
Abalone
Oyster
Crab
Herring
Flounder
Pollock
Squid
Scallop
Flounder
Trout (Sea)
Crab
Mullet
Flounder
Scup
Salmon
Shrimp
Mullet
Squid
Clam
Pollock
Anchovy
Scallop
Squid
Herring
Herring
Shrimp
Salmon
Snapper
Flounder
Flounder
Mackerel
Oyster
Shrimp
Winter
King
Witch
Skipjack
Atlantic
Calico
Shortfinned
Striped
Pink (Northern)
Winter
Pacific
Eastern
Winter
Sockeye (Red)
Red
Eastern
Tanner (Bairdi)
Round
Southern
Atl. Longfinned
Calico
Summer (Fluke)
Sand
Rock
Striped
Winter
Chum (Keta)
Pink (Northern)
Striped
Shortfinned
Surf
Walleye (Alaska)
Northern
Sea (smooth)
Atl. Longfinned
Atlantic
Atlantic
Brown
Chinock (King)
Red (EMU)
Witch
Yellowtail
Atlantic
Eastern
White
North Atlantic
Gulf
N. Atlantic
Pacific
North Atlantic
S. Atlantic
N. Atlantic
South Atlantic
Alaska
North Atlantic
California
S. Atlantic
North Atlantic
Pacific NWest
California
N. Atlantic
Alaska
North Atlantic
S. Atlantic
N. Atlantic
N. Atlantic
S. Atlantic
S. Atlantic
Gulf
N. Atlantic
Gulf
North Atlantic
North Atlantic
Alaska
Alaska
South Atlantic
N. Atlantic
N. Atlantic
Alaska
California
N. Atlantic
N. Atlantic
North Atlantic
North Atlantic
Gulf
Pacific NWest
Hawaii
N. Atlantic
North Atlantic
North Atlantic
N. Atlantic
Gulf
muscle
ROE
muscle
liver
whole
shucked
mantle, skinless
muscle
tail, peeled
muscle
whole
shucked
muscle
muscle
shucked
shucked, std.
meat
H & G tailless
muscle
liver
mantle, skinless
abductor muscle
muscle
muscle
meat
muscle
muscle
muscle
muscle
tail, peeled
muscle
mantle, skinless
shucked, whole
liver
whole
abductor muscle
mantle, skinless
headed
whole
tail, peeled
liver
muscle
muscle
muscle
muscle
shucked, select
tail, peeled
10
9
2
2
12
10
10
10
10
2
29
10
5
12
10
10
10
10
10
7
7
10
20
5 .
5
15
4
2
10
9
4
14
19
3
10
10
10
6
29
10
5
18
16
10
8
10
10
4
2
1
1
11
6
6
9
9
1
19
3
2
7
5
7
3
6
4
5
3
5
6
3
1
14
2
1
4
5
1
8
9
2
4
7
4
5
14
4
1
1
3
3
5
8
8
.113
.199
.090
.090
.050
.073
.073
.050
.050
.085
.064
.133
.100
.068
.078
.057
.126
.065
.095
.055
.088
.076
.119
.060
.169
.040
.070
.070
.086
.063
.133
.060
.070
.050
.080
.047
.078
.040
.065
.077
.149
.522
.156
.099
.050
.040
.040
-0.043
-0.043
-0.043
-0.043
-0.041
-0.041
-0.041
-0.041
-0.041
-0.040
-0.039
-0.038
-0.038
-0.037
-0.037
-0.036
-0.036
-0.036
-0.036
-0.036
-0.036
-0.036
-0.034
-0.033
-0.033
-0.033
-0.033
-0.033
-0.032
-0.032
-0.032
-0.031
-0.031
-0.030
-0.030
-0.029
-0.029
-0.029
-0.029
-0.029
-0.029
-0.029
-0.028
-0.028
-0.028
-0.028
-0.028
C-12
-------
Table C-l (continued)
Records in NMFS Report for which the difference between Method 3 and Method 2 is greater than
0.010 (sorted according to the magnitude of the difference, DIFF)
Mullet
Shrimp
Pollock
Shrimp
Shark
Scup
Flounder
Flounder
Salmon
Mackerel
Squid
Squid
Flounder
Trout (Sea)
Octopus
Flounder
Herring
Croaker
Perch
Shrimp
Oyster
Flounder
Flounder
Flounder
Salmon
Sole
Flounder
Bass
Cod
Halibut
Mackerel
Squid
Mullet
Herring
Mullet
Oyster
Shrimp
Herring
Bass
Flounder
Mullet
Cod
Flounder
Clam
Flounder
Herring
Scup
Striped
Pink
Pink (Northern)
Blue
Winter
Yellowtail
Chinock (King)
Spanish
Atl. Longfinned
Shortfinned
Gulf
Gray (Weakfish)
Marmuratus
Fourspot
Atlantic
Atlantic
Ocean (Pacific)
Alaska (Sidestriped)
Pacific (Giant)
Winter
Witch
Winter
Chum (Keta)
Dover
Winter
striped
Atlantic
Pacific
Atlantic
Atl. Longfinned
Striped
Atlantic
Silver (white)
Pacific (Giant)
Pink
Round
striped
Witch
Striped
Atlantic
Witch
Razor
Winter
Atlantic
Hawaii
Gulf
N. Atlantic
N. Atlantic
North Atlantic
North Atlantic
North Atlantic
North Atlantic
Alaska
South Atlantic
N. Atlantic
N. Atlantic
Gulf
N. Atlantic
Hawaii
N. Atlantic
North Atlantic
N. Atlantic
Pacific NWest
Alaska
Pacific NWest
North Atlantic
N. Atlantic
North Atlantic
Alaska
Pacific NWest
North Atlantic
N. Atlantic
N. Atlantic
Pacific NWest
North Atlantic
N. Atlantic
South Atlantic
North Atlantic
South Atlantic
Pacific NWest
Gulf
North Atlantic
Pacific NWest
N. Atlantic
Gulf
N. Atlantic
N. Atlantic
Pacific NWest
North Atlantic
North Atlantic
North Atlantic
muscle
tail, peeled
liver
tail, peeled
liver
muscle
muscle
muscle
muscle
muscle
mantle, skinless
mantle, skinless
muscle
whole
mantle, skinless
muscle
whole
muscle
muscle
tail, peeled
shucked, medium
muscle
muscle
muscle
muscle
muscle
muscle
muscle
liver
liver
muscle
mantle, skinless
muscle
muscle
muscle
shucked, small
tail, peeled
H & G tailless
muscle
muscle
muscle
liver
muscle
shucked
muscle
muscle
muscle
9
9
14
11
9
6
10
3
10
20
4
4
19
10
36
4
3
5
10
10
9
7
5
15
9
10
6
16
3
3
11
13
2
10
24
10
9
27
40
15
20
5
4
10
21
12
5
6
2
8
7
2
2
4
2
8
3
3
3
5
4
17
2
1
1
7
7
4
4
2
9
4
3
1
8
2
2
4
7
1
9
18
5
8
21
1
3
11
2
1
5
6
8
1
.047
.130
.053
.048
.127
.086
.072
.045
.038
.181
.040
.040
.101
.068
.058
.055
.080
.130
.040
.040
.060
.047
.065
.045
.059
.085
.147
.052
.040
.040
.069
.048
.050
.030
.035
.050
.030
.033
.858
.111
.043
.057
.088
.046
.076
.035
.105
-0.028
-0.028
-0.027
-0.027
-0.027
-0.027
-0.027
-0.027
-0.026
-0.026
-0.026
-0.026
-0.025
-0.025
-0.025
-0.025
-0.025
-0.025
-0.025
-0.025
-0.024
-0.024
-0.024
-0.024
-0.024
-0.024
-0.024
-0.024
-0.023
-0.023
-0.023
-0.023
-0.023
-0.023
-0.023
-0.023
-0.022
-0.022
-0.021
-0.021
-0.021
-0.021
-0.021
-0.021
-0.020
-0.020
-0.020
C-13
-------
Table C-l (continued)
Records in NMFS Report for which the difference between Method 3 and Method 2 is greater than
0.010 (sorted according to the magnitude of the difference, DIFF)
Sole
Shark
Squid
Squid
Mackerel
Oyster
Trout
Trout (Sea)
Shrimp
Scup
Croaker
Clam
Shrimp
Shrimp
Salmon
Squid
Flounder
Scallop
Flounder
Anchovy
Scallop
Halibut
Salmon
Croaker
Cod
Trout (Sea)
Shrimp
Anchovy
Crab
Mackerel
Squid
Flounder
Flounder
Flounder
Bass
Salmon
Clam
Croaker
Halibut
Clam
Oyster
Squid
Tuna
Flounder
Shrimp
Clam
Abalone
Petrale
Blacktip
Pacific
Atl. Longfinned
Atlantic
Eastern
Rainbow/Steelhead
Silver (White)
Brown
Atlantic
Razor
White
Pink (Northern)
Chum (Keta)
Atl. Longfinned
Witch
Atlantic Bay
Fourspot
Northern
Atlantic Bay
Pacific
Sockeye (Red)
Atlantic
Pacific (Gray)
Silver (White)
Pink (Northern)
Northern
Blue
Atlantic
Shortfinned
Southern
Fourspot
Winter
striped
Pink
Razor
Atlantic
Pacific
Hard
Eastern
Shortfinned
Yellowfin
Fourspot
Pink
Hard
Green
Pacific NWest
South Atlantic
California
N. Atlantic
North Atlantic
N. Atlantic
Pacific NWest
Gulf
Gulf
North Atlantic
S. Atlantic
Pacific NWest
S. Atlantic
N. Atlantic
Pacific NWest
N. Atlantic
N. Atlantic
S. Atlantic
N. Atlantic
California
S. Atlantic
Pacific NWest
Alaska
N. Atlantic
Alaska
Gulf
N. Atlantic
California
N. Atlantic
North Atlantic
N. Atlantic
Gulf
N. Atlantic
North Atlantic
California
Alaska
Alaska
Gulf
Pacific NWest
N. Atlantic
Gulf
N. Atlantic
Hawaii
N. Atlantic
Gulf
N. Atlantic
California
muscle
liver
whole
mantle, skinless
muscle
shucked
muscle
muscle
tail, peeled
muscle
muscle
shucked
tail, peeled
tail, peeled
muscle
whole
muscle
abductor muscle
muscle
whole
abductor muscle
muscle
muscle
muscle
liver
muscle
tail, peeled
whole
claw & body meat
muscle
mantle, skinless
muscle
muscle
muscle
muscle
muscle
shucked
muscle
liver
shucked, mixed
shucked
mantle, skinless
muscle
muscle
tail, peeled
shucked, littleneck
shucked
2
3
10
17
36
20
6
10
17
6
12
10
10
10
7
23
10
10
6
10
10
10
19
10
5
13
3
10
10
7
20
4
19
12
28
9
8
2
8
20
11
5
10
6
10
16
10
1
1
6
7
17
9
2
3
3
3
4
5
2
4
5
9
2
6
1
4
2
3
9
6
2
2
1
8
5
4
5
1
3
4
1
4
4
1
6
5
5
3
3
1
5
7
6
.045
.065
.038
.053
.046
.048
.063
.069
.113
.043
.061
.042
.096
.050
.030
.050
.093
.034
.109
.048
.091
.062
.041
.033
.047
.114
.055
.025
.037
.033
.069
.067
.103
.051
.432
.039
.035
.035
.025
.065
.038
.030
.054
.093
.034
.038
.029
-0.020
-0.020
-0.020
-0.020
-0.019
-0.019
-0.019
-0.019
-0.019
-0.019
-0.019
-0.019
-0.018
-0.018
-0.018
-0.018
-0.018
-0.017
-0.017
-0.017
-0.017
-0.017
-0.017
-0.017
-0.017
-0.017
-0.017
-0.016
-0.016
-0.016
-0.016
-0.016
-0.015
-0.015
-0.015
-0.015
-0.015
-0.015
-0.015
-0.015
-0.015
-0.015
-0.015
-0.015
-0.015
-0.014
-0.014
C-14
-------
Table C-l (continued)
Records in NMFS Report for which the difference between Method 3 and Method 2 is greater than
0.010 (sorted according to the magnitude of the difference, DIFF)
Herring
Shrimp
Herring
Shrimp
Shrimp
Clam
Mullet
Oyster
Oyster
Scup
Oyster
Anchovy
Croaker
Salmon
Oyster
Clam
Croaker
Haddock
Oyster
Perch
Snapper
Lobster
Tuna
Clam
Salmon
Flounder
Salmon
Scallop
Scup
Squid
Haddock
Squid
Shrimp
Flounder
Salmon
Flounder
Clam
Shrimp
Salmon
Perch
Haddock
Crab
Salmon
Round
Pink (Northern)
Atlantic
White
Brown
Hard
Striped
Eastern
Pacific (Giant)
Eastern
Northern
Atlantic
Sockeye (Red)
Pacific (Giant)
Hard
Atlantic
Eastern
Ocean (Pacific)
Vermilion
Atlantic Spiny
Skipjack
Butter
Chinock (King)
Windowpane
Chinock (King)
Pink
Shortfinned
Shortfinned
Brown
Witch
Coho (Silver)
Fourspot
Butter
Pink (Northern)
Sockeye (Red)
Ocean (Redfish)
King
Pink
North Atlantic
N. Atlantic
North Atlantic
Gulf
Gulf
N. Atlantic
Hawaii
Gulf
Pacific NWest
North Atlantic
N. Atlantic
California
Gulf
Alaska
Pacific NWest
N. Atlantic
S. Atlantic
N. Atlantic
S.Atlantic
Pacific NWest
South Atlantic
Gulf
Pacific
Pacific NWest
Alaska
N. Atlantic
Alaska
Alaska
North Atlantic
N. Atlantic
N. Atlantic
N. Atlantic
Gulf
N. Atlantic
Pacific NWest
N. Atlantic
Pacific NWest
N. Atlantic
Alaska
North Atlantic
N. Atlantic
Alaska
Alaska
H & G tailless
tail, peeled
whole
tail, peeled
tail, peeled
shucked, cherrysto
muscle
shucked
shucked, medium
muscle
shucked, select
whole
muscle
muscle
shucked
shucked, chowder
muscle
liver
shucked
liver
muscle
tail meat
muscle
shucked, ex. large
muscle
muscle
muscle
abductor muscle
muscle
mantle, skinless
muscle
mantle, skinless
tail, peeled
muscle
muscle
muscle
shucked
tail, peeled
muscle
muscle
muscle
meat
muscle
7
9
17
17
13
30
13
20
10
11
16
10
10
10
10
49
2
2
10
8
2
12
20
9
9
7
10
5
5
5
5
9
3
15
10
18
4
4
10
14
9
9
10
5
4
16
3
7
13
12
12
6
10
9
9
9
9
4
14
1
1
5
4
1
3
3
4
3
1
8
4
3
4
1
1
1
2
5
2
3
1
4
1
1
3
6
.025
.037
.020
.085
.031
.037
.020
.028
.028
.020
.029
.020
.020
.020
.038
.050
.030
.030
.030
.030
.030
.055
.088
.033
.042
.090
.020
.020
.025
.020
.065
.112
.040
.092
.028
.108
.020
.050
.033
.161
.105
.038
.023
-0.014
-0.014
-0.014
-0.014
-0.014
-0.014
-0.014
-0.014
-0.014
-0.014
-0.014
-0.014
-0.014
-0.014
-0.013
-0.013
-0.013
-0.013
-0.013
-0.013
-0.013
-0.013
-0.012
-0.012
-0.012
-0.012
-0.012
-0.012
-0.012
-0.012
-0.012
-0.012
-0.012
-0.012
-0.012
-0.011
-0.011
-0.011
-0.011
-0.011
-0.011
-0.01 1
-0.011
C-15
-------
APPENDIX D
HUMAN FISH CONSUMPTION AND MERCURY INGESTION
DISTRIBUTIONS
-------
TABLE OF CONTENTS
D. 1 Introduction 1
D.2 Methods and Assumptions 1
D.3 Population Exposure Equations 1
D.4 Input Distributions 2
D.4.1 Mercury Digestion per Fish Meal (Kg^^) 2
D.4.2 Fish Consumption per Fish Meal (Fish^,^ 3
D.4.3 Number of Fish Meals per Month (Nmeals) 4
D.5 Simulation Output 6
D.6 Sensitivity Analysis 8
D.6.1 Adequacy of Input Distribution Fit 8
D.6.2 Impact of Assumptions on Simulation Output 13
D.6.2 Other Sources of Uncertainty 15
D.7 Conclusions 15
D.8 References 16
D-i
-------
LIST OF TABLES
Distributions for Selected Populations 3
D-2 Fish,^^ Distributions for Selected Populations 4
D-3 Nmeals Distributions for Selected Populations 5
D-4 HgDAILY Distributions for Selected Populations: Adults 6
D-5 HgDAILY Distributions for Selected Populations: Children 7
D-6 FCDAILY Distributions for Selected Populations: Adults 7
D-7 FCDAILY Distributions for Selected Populations: Children 8
D-8 Comparison of HgDAILY Output for Alternate Fits 15
D-ii
-------
LISTOF FIGURES
D-l Quantile-Quantile Plots for Hg^^ Distributions 10
D-2 Quantile-Quantile Plots for FishMEAL Distributions 11
D-3 Quantile-Quantile Plots for Nmeals Distributions 12
D-4 Quantile-Quantile Plots for Mixtures-Distribution Fits 14
D-iii
-------
D.I Introduction
This Appendix presents an analysis of the third National Health and Nutrition Examination Survey
(NHANES ffl) data on frequency of fish and shellfish consumption over an one-month interval, 24-hour
recall data for consumption of fish and shellfish, body weight (in kilograms) and mean mercury
concentrations in fish and shellfish. These data were utilized to estimate national exposure distributions
for ingestion of mercury from fish and shellfish for a time period defined as one month or 30 days.
Mathematical distributions were fit to data addressing the number and size of fish meals and associated
mercury ingestion for several ethnic and racial groups within the general U.S. population. Analyses for
higher-frequency fish consumers, women of child-bearing age and children were also performed.
D.2 Methods and Assumptions
All variables in this analysis were assumed to be lognormally distributed and independent.
Parameters of the lognormal distributions are expressed as the geometric mean (GM) and the geometric
standard deviation (GSD). The geometric mean (and median) is defined as eM, where u is the mean of the
logarithms of the observations. The geometric standard deviation is defined as e°, where o is the standard
deviation of the logarithms of the observations.
The data available for estimation of distribution parameters were in the form of cumulative
distribution percentiles and moments (arithmetic mean and standard deviation). The primary approach to
fitting lognormal distributions to the data was by the method of moments, in which the sample mean and
sample standard deviation, themselves, are used as estimates of the parameters. For the lognormal, the
parameters are determined in log space (mean and standard deviation of the logs of the observations). In
this analysis, the GM and GSD were estimated from the arithmetic mean and standard deviation using
analytic formulas relating the arithmetic and geometric moments (Evans et al., 1993). In some cases the
arithmetic moments did not provide reasonable estimates of the geometric moments. In these cases
parameter estimation focused on the range between the 50th (median) and 95th percentiles. (a was
assumed to be the log of the median, o was estimated as the average of the difference of the logs of the
75th, 90th and 95th percentiles and u, divided by the corresponding z-score from the standard unit normal
distribution. Distributions derived by the percentile method should be considered to be less reliable than
by the method of moments. The fit of the distributions to the data in this range was assessed by graphical
analysis and percentile matching.
D.3 Population Exposure Equations
Daily mercury ingestion from fish consumption is given as Equation 1.
H8DA1LY = 3Q (1)
where
HgDAELY is daily ingestion of total mercury (ug/kgfew-day),
HgMEAi is the ingestion of total mercury per fish meal (ug/kgfew-meal),
Nmeals is the number of fish meals per month (month ') and
30 is the number of days per month (days/month).
D-l
-------
Daily fish consumption is given as Equation 2.
x Nmeals
MEAL
30
where
FCDAILY is daily per capita fish consumption (g/day),
FishvEAL is fish consumption per fish meal (g/meal),
Nmeals is the number of fish meals per month (month"1) and
30 is the number of days per month (days/month).
Equations 1 and 2 are solved using analytic methods for multiplying lognormal distributions (Aitchison
and Brown, 1966; see also Appendix D to Volume 3 of this Report).
D.4 Input Distributions
This section presents the development of each of the input distributions for Equations 1 and 2.
The basis for each distribution is given. Moments and percentiles for all empirical distributions were
based on population weighted frequencies. That is, the sample observation frequencies were projected to
the national population weighted by sex and age frequencies in the national population (NHANES HI).
D.4.1 Mercury Ingestion per Fish Meal (HgMEAL)
. distributions were based on 24-hour fish (and shellfish) consumption recall data for
consumers, only (per user), reported in NHANES HI and average mercury concentrations reported for each
fish species consumed. Consumption-mass-weighted mercury concentrations for individual species were
summed across all species consumed by each survey respondent (consumers only) and divided by the
respondent's body weight. Simplifying assumption were made that all the mercury was methylmercury
(MeHg) and was ingested in a single meal. Empirical HgMEAL distributions were constructed for six
subpopulations: the Caucasian (nonHispanic) general population ("White"), the African-American
(nonHispanic) general population ("Black"), the Mexican-American general population ("Hispanic"), a
more frequent fish-consuming population that included Asians, Pacific Islanders, Native Americans and
Caribbean Islanders ("Other"), 15 to 44 year-old females across all groups ("Women") and 3 to 6 year-old
children across all groups ("Children"). Women of this age group were selected as the MeHg Reference
Dose (RfD) based primarily on effects in offspring of women exposed to MeHg during pregnancy. This
particular age group of children was selected because of its much higher mercury exposure rate than other
child age groups. The HgMEAL empirical distributions and lognormal approximations for each of these
subpopulations are given in Table D-l.
D-2
-------
Table D-l
Distributions for Selected Populations
(ug/kg6n>-meal)
Distribution:
Empirical
n
mean
std. dev.
50th percentile
75th percentile
90th percentile
95th percentile
Lognormal
method
GMa
GSDh
75th percentile
90th percentile
95th percentile
mean
std. dev.
Population
White
Black
Hispanic
Other
Women
Children
1392
0.19
43.05
0.12*
0.26
0.50
0.73
1278
0.23
19.69
0.15
0.32
0.57
0.77
914
0.22
11.42
0.15
0.31
0.58
0.77
265
0.23
50.00
0.12
0.32
0.61
0.97
882
0.17
0.28
0.10
0.22
0.39
0.53
415
0.40
0.56
0.28
0.49
0.77
1.08
percentiles
0.12
3.01
0.25
0.50
0.74
0.22
0.34
percentiles
0.15
2.82
0.31
0.57
0.83
0.26
0.36
percentiles
0.15
2.91
0.30
0.58
0.85
0.26
0.38
percentiles
0.12
3.77
0.30
0.66
1.07
0.29
0.64
moments
0.09
3.14
0.19
0.38
0.58
-
-
moments
0.23
2.83
0.47
0.88
1.29
-
-
a Geometric Mean (and 50th percentile)
b Geometric Standard Deviation
*Rounded to 2 significant figures.
D.4.2 Fish Consumption per Fish Meal (FishMEALj
FishMEAL distributions were based on 24-hour fish (and shellfish) consumption recall data for
consumers, only (per user), reported in NHANES ffl. A simplifying assumption was made that all the fish
was consumed in a single meal. Fish^^ distributions were constructed for the same five subpopulations
as for HgMEAL. The FishMEAJL empirical distributions and lognormal approximations for each of these
subpopulations are given in Table D-2.
D-3
-------
Table D-2
Distributions for Selected Populations
(g/meal)
Distribution:
Empirical
n
mean
std. dev.
50th percentile
75th percentile
90th percentile
95th percentile
Lognormal
method
Gma
GSDb
75th percentile
90th percentile
95th percentile
mean
std. dev.
Population
White
Black 1 Hispanic
Other
1394
109
16752
65.5*
126
222
291
1282
128
8004
77.5
151
263
356
920
108
4856
64.7
129
222
318
266
106
15277
67.5
122
234
297
Women
883
103
116
66.0
131
228
288
Children
415
57
55
43.3
66.2
113
151
percentiles
65.5
2.57
124
220
310
102
123
percentiles
77.5
2.60
148
264
373
122
150
percentiles
64.7
2.67
125
228
326
105
134
percentiles
67.5
2.50
125
219
305
103
119
moments
68.6
2.47
126
219
304
-
-
moments
40.7
2.26
70.6
116
156
-
-
a Geometric Mean (and 50th percentile)
b Geometric Standard Deviation
* Rounded to 3 significant figures.
D.4.3 Number of Fish Meals per Month (Nmeals)
Nmeals distributions were based on monthly fish (and shellfish) consumption frequency data for
all respondents (per capita) reported in NHANES HI. The frequency of fish meals consumed per month
was treated as a continuous variable for estimation of long-term fish consumption rates. Values at the
reference percentiles (50th, 75th, 90th and 95th) were estimated by linear interpolation from cumulative
discrete frequency distributions. As these data are from the general population (not just fish consumers), a
significant fraction of respondents reported eating no fish in the last month (11-14%). Nmeals
D-4
-------
distributions were constructed for the same subpopulations as for Kg,^^ and Fish,^^ except for
"Women" and "Children," for which data were not available. An Nmeals distribution for the general
population across all other groups ("All") was used as a surrogate for "Women" and "Children." Nmeals
empirical distributions and lognormal approximations for each of these subpopulations are given in Table
D-3.
Table D-3
Nmeals Distributions for Selected Populations
(month1)
Distribution
Empirical
n
mean
std. dev.
50th percentile
75th percentile
90th percentile
95th percentile
99th percentile
maximum
Lognormal
method
GM"
GSDh
75th percentile
90th percentile
95th percentile
99th percentile
Population
White
Black
Hispanic
Other
All
7410
5.6
6.2
3.4*
7.2
12
16
30
150
5594
6.5
8.2
3.8
8.0
13
18
31
220
5394
4.7
5.8
2.9
5.8
11
14
28
150
785
8.3
2.6
4.1
9.9
22
31
43
61
moments
3.7
2.5
6.8
12
16
30
moments
4.0
2.7
7.8
14
20
39
moments
3.0
2.6
5.7
10
14
28
moments
5.3
2.6
10
18
25
19
19,200
5.8
6.9
3.5
7.4
12
17
30
220
moments
3.8
2.5
7.1
12
18
33
" Geometric Mean (and 50th percentile)
b Geometric Standard Deviation
* Rounded to 2 significant figures.
D-5
-------
D.5 Simulation Output
The results of the solution of Equation 1 (HgDAILY) are given for adults and children in Tables D-4
and D-5, respectively. The percentile at which the MeHg RfD falls in the HgDAILY output is given for
adults (Table D-4). Direct comparison to the RfD is most appropriate for women of child-bearing age, as
the MeHg RfD is based, primarily, on effects in the offspring of exposures to their mothers during
pregnancy (see Volume V of this report; also U. S. EPA, 1997). That is, although the effects were
observed in children, the exposure (and it's associated metric) was to the mother. The RfD is designed to
be protective of all sensitive subpopulations. In this case (MeHg), the developing fetus was judged to be
the most sensitive population. An uncertainty factor was included in the RfD to account for the lack of
data on post-natal development, among other factors.
The results of the solution of Equation 2 (FCDAjLY) are given for adults and children in Tables D-6
and D-7, respectively. The percentile at which fish ingestion exceeds 100 g/day in the FishDAILy output is
also shown.
Table D-4
Distributions for Selected Populations: Adults
(ug/kgfcw-day)
Percentile
50th
75th
90th
95th
RfD Percentile
Population
White'
0.015
0.039
0.092
0.15
91.0
Black"
0.020
0.053
0.13
0.21
86.8
Hispanic0
0.015
0.047
0.11
0.18
91.0
Other"
0.021
0.064
0.17
0.31
82.7
Women'
0.011
0.030
0.074
0.13
93.2
"CM = 0.0149, GSD = 4.145
"GM = 0.0204, GSD = 4.153
CGM = 0.0145, GSD = 4.216
dGM = 0.0214, GSD = 5.123
d GM = 0.01 ll.GSD = 4.382
D-6
-------
Table D-5
Distributions for Selected Populations: Children
(ug/kgin'-day)
Percentile
50th
75th
90th
95th
Ethnicity
All
Groups'
0.029
0.075
0.18
0.29
White"
0.029
0.072
0.17
0.28
Black0
0.031
0.082
0.19
0.33
Hispanic"
0.023
0.060
0.14
0.24
Other'
0.041
0.11
0.25
0.42
aGM = 0.0292, GSD = 4.050
h CM = 0.0286, GSD = 3.961
CGM = 0.0311, GSD = 4.173
dGM = 0.0230, GSD = 4.130
eGM = 0.0411, GSD = 4.102
Nmeals distributions from general population for each group (not child-specific)
HgMEAL distribution from 3-6 year-old children across ethnicities (not group-specific)
Table D-6
FCDA1LV Distributions for Selected Populations: Adults
(g/day)
Percentile
50th
75th
90th
95th
100 g percentile
Population
White"
8.1
19
43
69
97.3
Black"
10
26
60
99
95.1
Hispanicc
6.4
16
37
62
97.7
Other0
12
29
65
105
94.6
Women"
8.6
21
46
73
97.0
aGM = 8.08, GSD = 3.685
"GM = 10.4, GSD = 3.925
CGM = 6.43, GSD = 3.957
CGM= 11.9, GSD = 3.751
"GM = 8.63, GSD = 3.668
D-7
-------
Table D-7
FCDAay Distributions for Selected Populations: Children
(g/day)
Percentile
50th
75th
90th
95th
100 g percentile
Ethnicity
AU
Groups'
5.1
12
25
39
>99
White"
5.0
11
24
37
>99
Black0
5.5
13
28
44
99
Hispanic*
4.0
9.5
20
32
>99
Other'
7.2
17
36
57
98
"GM = 5.12, GSD = 3.456
bGM = 5.01, GSD = 3.370
CGM = 5.46,GSD = 3.573
"GM = 4.04, GSD = 3.532
CGM = 7.18, GSD = 3.506
Nmeals distributions from general population for each group (not child-specific)
FishMEAL distribution from 3-6 year-old children across ethnicities (not group-specific)
D.6 Sensitivity Analysis
D.6.1 Adequacy of Input Distribution Fit
A general trend for fitting input distributions by the percentile method was for higher estimates of
o at lower percentiles but with fairly good agreement in the targeted range (75th to 95th percentiles);
coefficients of variation for o estimates for a given data set were in the range of 0.03 to 0.1. Distributions
fit by this method were not particularly good approximations of the data outside these percentile ranges.
The impact of overestimating the lower end of the input distributions on the output of Equations 1 and 2 is
discussed in the next section.
Quantile-quantile plots (QQ plots) are shown for each of the distributions in Figures D-l, D-2 and
D-3, which show the Hg^^, FishMEAL, and Nmeals distributions, respectively. These figures plot the z-
scores of the logs of the observations against the z-scores for the corresponding fitted lognormal
distribution (normal in log space). The z-scores are the number of standard deviations above or below the
median. A z-score of 2 corresponds to about the 95* percentile (z= -2 = 5th percentile). The 99th and 99.9th
percentiles correspond to z-scores of 2.33 and 3.1, respectively. As these plots compare the logs of the
distributions, zeroes in the raw data are not included. Zeroes were included, however, in the fitting process
for those variables fit by the method of moments. For those distributions fit by the percentile method, the
data points (50th, 75*, 90th and 95th percentiles) used in the fitting process are indicated by filled symbols
on the Figures.
D-8
-------
The solid straight lines on the QQ plots represent perfect fits. That is, a perfect fit would result in
all the points lining up along the line. The direction of deviations from the line can be used to assess the
direction of the prediction error. If the points curve below the line at either end, the fitted distribution will
under predict actual values at that end. Conversely, if the points curve above the line, the fitted
distribution will over predict. The tendency to over predict the lower tail can be seen for all of the
variables. This tendency is quite marked for a number of variables, particularly for the ones fitted by the
percentile method. The upper tails of the empirical distributions are all fairly well represented by the fitted
distributions, even for extreme values. Nmeals/Other is an exception, but the poor fit is well beyond the
99th percentile; the data points above the 99th percentile are single observations. The effect of over
prediction in the lower tail on the analytic solutions of Equations 1 and 2 will be to greatly exaggerate the
lower percentiles. There will also be a tendency to over predict the upper percentiles, but probably not by
a large amount. Deviations from the fit line at z-scores of less than -3 should have no effect on the output
In general, the magnitude of the over prediction is difficult to assess from the QQ plots, but will be
considerably less than that resulting from over prediction in the upper tails of the input distributions. The
best predictions should be for both outputs for "Women" and "Children," given the better combined fit for
HgMEAL, FishMEAL, and Nmeals for these two groups.
D-9
-------
Figure D-l
Quantile-Quantile Plots for H
Distributions
WHITE
3.0-
2.5-
2.0-
1 5-
10-
05-
00-
-05-
1.0-
-05 05 15 25 35
empirical z-score
BLACK
3.0-
2.5-
2.0-
1.5-
1.0-
05-
00-
0.9
-1 0
1.9
-20
25-
-70 -55 -40 -25 -10 00 10 20 30
empirical z-score
HISPANIC
OTHER
K
30-
25-j
20-;
15J
S 1 0-
05-
00-
-1 0-
-1 5-
-2tH
-25-
30-
25-
20-
1 5-
10-
05-
00-
-05-
-1 rr
-40 -30
-20 -10 00
empirical z-score
10 20 30
-10 00 05 10 15 20 25 30
empirical z-score
WOMEN
CHILDREN
30-
25-j
I
OOJ
30-
2.5-
20-
1 5-
1 0-
05-
00-
-05-
-1.0
1.9
! T~
-I
00 05 10 15 20 25
empirical z-score
-1.0 00 10 20 30
empirical z-score
D-10
-------
normal z-score
fo-^*- 0°°-
9
5
£
O
6 .
normal 7-score
O m c? <4* . *? *7 ..5? ^7... ? "i* ?
^ In q> c/1 gy CJp cp
O
F
O
33
m
Q en
J5
Si' ^
m
3J
O
-------
Figure D-3
Quantile-Quantile Plots for Nmeals Distributions
WHITE
40-
35-
3.0-
25-
2.0-
* 1-5-
10-
05-
o.o-
-0.5-
-1 O
00 05 10 1.5 2.0 2.5 3.0 35 4.0
empirical z-score
BLACK
3.5-
30-
25-
2.0-
1.5-
1.0-
0.5-
00-
-OS
00 05 10 1.5 20 25 30
empirical z-score
35 4.0
HISPANIC
OTHER
"I
20-i
i
= 1 ^
05^
30-
25-
20-
9
1 151
1 1.0-
8
05-
oo-
-0*
00 05 10 15 20 25 30 35 40
empirical z-score
-10 -05 00 05 10
empirical z-score
15 20 25
ALL
25-
£
20-
75 '5-
I 10-
05-
oo-
0.5-
-10 00 05 10 15 20 25 30 35 40
empirical z-score
D-12
-------
D.6.2 Impact of Assumptions on Simulation Output
The assumption that the 24-hour recall data represent one fish meal is obviously false for all
respondents who reported more than 30 fish meals per month. The assumption will result in
overestimation of both HgDMLY and FCDAILY at higher percentiles. The 30 fish meal per month mark falls at
the 99th percentile or higher for all groups except "Other," for which the 95th percentile is 31.4 fish meals
per month. The bias in HgDAJLy and FCDAILy for groups other than "Other" should not be significant at the
95th percentile and lower, but this assumption was not tested. The results for "Other" above the 90th
percentile should be considered to be conservative.
Correlation of input variables was not considered in this analysis. Data for "Women" suggest that
there is a slight positive correlation between Nmeals and the other two variables, with a more noticeable
difference in Fish,^^ for those respondents reporting zero or one fish meal in the last month. That is,
those individuals who had a low frequency of fish consumption also tended to eat less fish per meal (70
g/meal vs 108 g/meal for respondents reporting two or more fish meals per month). The result of this
correlation would be an over prediction of FCDlMLY- The magnitude of the over prediction could not be
estimated without the specific body weight of the individuals, but was judged to be small. The correlation
of Nmeals and HgMEAL was very weak and was not expected to have any impact on the output. The effect
of correlations on simulation output is generally smaller than that arising from the form of the assigned
distribution (Bukowski et al., 1995).
The impact of the simplifying lognormal assumptions on the output of Equations 1 and 2 was
investigated by defining the input distributions as mixtures (mixtures approach) and then solving the
equations by Monte Carlo analysis. That is, separate distributions were fit to discrete segments of the
empirical data rather than assuming a single mathematical form for the entire distribution. For several data
sets where the number of zeroes was high, the proportion of zeroes was modeled as a delta function
(spike), with a lognormal distribution fit to the nonzero data (delta method). For one data set with no
zeroes, a log-triangular distribution was fit to the proportion of the data set that did not appear to be
lognormal (the lower 25%) and a lognormal was fit to the remainder (two-distribution method). In each
case, a composite mixtures distribution was constructed by Monte Carlo simulation.
Figure D-4 shows the QQ-plots for the mixtures distribution fits to selected variables. Two of the
worst-fitting HgMEAL data sets (Hispanic and Other) were selected for this part of the analysis. The
corresponding Nmeals data sets were also analyzed so that output distributions (Equation 1) could be
generated. HgMEAL/Hispanic, was fit by the two-distribution method and the rest by the delta method.
Distribution quantiles, in natural log units, are shown in these plots instead of z-scores, as the fitted
distributions are not entirely lognormal. Otherwise, the visual fit of the distributions can be compared
directly with the corresponding QQ-plots in Figures D-l and D-3. The mixtures approach provided a
better overall fit for HgMEAL, particularly at the lower end, the lower three points for Mg^^/Hispanic being
an exception. These data points, however, represent less than 1% of the distribution and would have no
effect on the output. Upper percentile estimates for the mixtures approach are similar to those estimated by
the simple lognormal assumptions. The Nmeals distributions estimated by the mixtures approach showed
only slightly better fit (or none at all) in the lower percentiles at the expense of a slightly poorer fit at the
upper extreme. Fits to Nmeals/White and Nmeals/All were similar to Nmeals/Hispanic. Overall, the
mixtures approach did not improve the fit to Nmeals.
D-l 3
-------
Figure D-4
Quantile-Quantile Plots for Mixtures-Distribution Fits
HgMeal (Hispanic)
i.o-
05-
S. -10-
I -'»
I -20-
I '
| -30-
5 -35-
» -4.0-
'iI i 1 1 1 1 1 1 1 1 1 1 1 i 1
-65 -55 -45 -35 -2.5 -1.5 -0.5 0.5 15
empirical quantiles (natural log)
HgMeal (Other)
2.0-
1.5-
1.0-
f 05-
« 0.0-
| -O.S
f 1-°
I -1.9
§ -2.O
| -2.9
| -3.0
| -3.S
-4.0
-60
i 1 1 1 1 ri 1 1
-40 -3.0 -2.0 -1.0 0.0
empirical quantiles (natural log)
Nmeals (Hispanic)
Nmeals (Other)
2 1 cr
E I
50-
45-
4.0-
3.5-
30-
25-
20-
1 5-
1 0-
05-
00 05 10 15 20 25 30 35 40 45
empirical quantiles (natural log)
10 15 20 25 30 35
empirical quantiles (natural log)
Results of the Monte Carlo simulations of Equation 1 using the mixtures distributions are given in
Table D-8. The output was simulated with mixtures distributions for both inputs (HgMEAL and Nmeals) and
for HgMEAL, only, as the mixtures approach did not provide a better fit for Nmeals. The results in Table
D-8 show little effect from the simple lognormal assumption for the inputs in this limited comparison.
Further analysis using the full data sets and other parametric fitting or nonparametric methods would be
useful for resolving the remaining distribution fit issues.
D-14
-------
Table D-8
Comparison of HgDAILY Output for Alternate Fits
(pgfkgbw-day)
Group
method of
distribution
fit
Percentiles
50th
75th
90th
95th
99th
Hispanic
simple
lognormal"
0.015*
0.038
0.092
0.15
0.41
HgMEAl.
. mixture15
both
mixtures0
Other
simple
lognormal*
HgM£AL
mixture"
both
mixtures'
0.014
0.038
0.086
0.14
0.40
0.019
0.047
0.11
0.18
0.45
0.021
0.064
0.17
0.31
0.96
0.021
0.066
0.18
0.33
0.98
0.020
0.071
0.20
0.36
1.1
" from Table D-4
bmixture for HgMEAL, only; lognormal Nmeals from Table D-3
c mixtures for both inputs
* Rounded to 2 significant figures.
D.6.2 Other Sources of Uncertainty
Sources of uncertainty or bias that have not been considered in this analysis include fish mercury
concentrations, mercury speciation in fish and shellfish, and population weights. The mercury
concentrations in the fish and shellfish were average concentrations for the identified fish species. Data
were available on the distribution of mercury in each species but were not considered for this analysis.
These data would provide bounds on the percentile values estimated in this analysis but would not change
the median estimates for each percentile. The mercury in all "fish" species was assumed to be
methylmercury, which is a fairly sound assumption for finfish (Bloom, 1992), but somewhat less so for
shellfish and other species. The impact of this assumption on the simulation output was not investigated
but was assumed to be small. The uncertainty in the population weighting protocol in NHANES in was
not investigated either.
D.7 Conclusions
The derived distributions are thought to be more characteristic of month-long patterns offish and
shellfish consumption than are either of the two individual distributions that formed the input variables.
The resulting derived distribution was done to maximize fit between the 75th and 95th percentiles.
D-15
-------
D.8 References
Aitchison, J. and J. A. C. Brown (1966). The Lognormal Distribution. University Press, Cambridge.
Barnes, D. G. and M. L. Dourson (1988). "Reference dose (RfD): Description and use in health risk
assessment," Regul. Toxicol. Pharmacol. 8:471-486.
Bloom, N.S. (1992). On the chemical form of mercury in edible fish and marine invertebrate tissue. Can.
J. Fish. Aquat. Sci. 49:1010-1017.
Bukowski, J., L. Korn and D. Wartenberg (1995)."Correlated Inputs in Quantitative Risk Assessment: The
Effects of Distributional Shape," Risk Analysis 15:215-219.
Evans, M., N. Hastings and B. Peacock (1993). Statistical Distributions. 2nd Edition. John Wiley and
Sons, Inc., New York, NY, pp. 42-44.
U. S. EPA (1988). Integrated Risk Information System (IRIS), Background Document 1, National Center
for Environmental Assessment, Cincinnati Office, Cincinnati, OH.
U. S. EPA (1997). Integrated Risk Information System (IRIS), On-Line Assessments, National Center for
Environmental Assessment, Cincinnati Office, Cincinnati, OH.
D-16
-------
TECHNICAL REPORT DATA
(Please read Instructions on reverse before completing)
1. REPORT NO.
EPA-452/R-97-006
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Mercury Study Report to Congress. Volume IV. An Assessment of Exposure to
Mercury in the United States.
5. REPORT DATE
December. 1997
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Dr. Kathryn R. Mahaffey, and Mr. Glenn E. Rice
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
U.S. Environmental Protection Agency
Office of Research and Development
National Center for Environmental Assessment
Washington, DC 20460
10 PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
Office of Air Quality Planning and Standards
Office of Air and Radiation
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711;
National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
Washington, DC 20460
13. TYPE OF REPORT AND PERIOD COVERED
December, 1997
14. SPONSORING AGENCY CODE
EPA/200/04
15. SUPPLEMENTARY NOTES
U.S. EPA Project Officer: Martha H. Keating
16. ABSTRACT
This volume assesses exposure of the U.S. general population to methylmercury through consumption of fish and shellfish.
Based on determination of the impact of ambient releases of mercury, humans and piscivorous wildlife are exposed to mercury
as methylmercury through consumption of fish and shellfish. Analyses of patterns of fish consumption by humans were based on
contemporary food consumption surveys of nationally representative populations hi the United States, and for subpopulations
identified as consumers of substantially higher amounts of fish/shellfish than are more typical consumers. These subpopulations
include: Native American Tribal groups, Alaskan natives, persons of Asian/Caribbean/South Pacific Island ethnicity, and
subsistence fishers. Mercury concentrations in marine/fresh water/estuarine species are described. Commercial data on
quantities of seafood available and sources of fish/shellfish consumed are provided based on commercial and National Marine
Fisheries Service data bases. Mercury exposures are calculated for multiple groups, but particularly for women of childbearing
age, and for children. Young children are exposed to two-to-three times higher levels of methylmercury from fish and shellfish
(on a per kilogram body weight basis) than are adults. Alternative presentations of patterns of fish/shellfish consumption (e.g.,
daily, per capita, consumers only, and month-long patterns) for the general population are provided. Assessment of mercury
exposures based on biomonitoring of mercury in hair and blood among North American groups are provided. A brief summary
of additional sources of mercury (e.g., occupational exposures) is included. Sources of variability and uncertainty are described,
and when possible, quantitated.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b. IDENTIFIERS/OPEN ENDED TERMS
c COSATI Field/Group
Mercury; Methylmercury; Clean Air Act; Diet Records;
Food habits; Food supply; Toxicology; Fetal
development; Child development disorders; Air
pollutants, chemical; Water pollutants, chemical;
Bioaccumulate.
Air Pollution control
18 DISTRIBUTION STATEMENT
Release Unlimited
19. SECURITY CLASS (Report)
Unclassified
21. NO. OF PAGES
293 pp.
20. SECURITY CLASS (Page)
Unclassified
22. PRICE
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