United States
Environmental Protection
Agency
Office of Health and
Environmental Assessment
Washington DC 20460
EPA-600/8-84-026A
December 1984
Review Draft
Research and Development
r/EPA
Health Assessment
Document for
Beryllium
Review
Draft
(Do Not
Cite or Quote)
NOTICE
This document is a preliminary draft. It has not been formally
released by EPA and should not at this stage be construed to
represent Agency policy. It is being circulated for comment on its
technical accuracy and policy implications.
-------
(Do Not EPA-600/8-84-026A
Cite or Quote) December 1984
Review Draft
Health Assessment Document
for
Beryllium
NOTICE
This document is a preliminary draft. It has not been formally released by EPA and should not at
this stage be construed to represent Agency policy. It is being circulated for comment on its
technical accuracy and policy implications.
Environmental Criteria and Assessment Office
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
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DISCLAIMER
This report is an external draft for review purposes only and does not
constitute Agency policy. Mention of trade names or commercial products does
not constitute endorsement or recommendation for use.
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PREFACE
The Office of Health and Environmental Assessment, in consultation with
other Agency and non-Agency scientists, has prepared this health assessment
to serve as a "source document" for Agency-wide use. Specifically, this
document was prepared at the request of the Office of Air Quality Planning
and Standards.
In the development of this assessment document, the scientific literature
has been inventoried, key studies have been evaluated, and summary/conclusions
have been prepared such that the toxicity of beryllium is qualitatively and
where possible, quantitatively, identified. Observed effect levels and dose-
response relationships are discussed where appropriate in order to place
significant health responses in perspective with observed environmental
levels.
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ABSTRACT
The chemical and geochemical properties of beryllium resemble those of
aluminum, zinc, and magnesium. This resemblance is primarily due to similar
ionic potentials which facilitate covalent bonding. The three most common
forms of beryllium in industrial emissions are the metal, the oxide, and the
hydroxide.
The main routes of beryllium intake for man and animals are inhalation
and ingestion. While the absorption of ingested beryllium is probably quite
insignificant, the chemical properties of beryllium are such that transforma-
tion of soluble to insoluble forms of inhaled beryllium results in long
retention time in the lungs. The tissue distribution of absorbed beryllium
is characterized by main depositions in the skeleton where the biological
half-time is fairly long.
The lung is the critical organ of both acute and chronic non-carcinogenic
effects. However, unlike most other metals, the lung effects caused by
chronic exposure to beryllium may be combined with systemic effects, of which
one common factor may be hypersensitization. Certain beryllium compounds
have been shown to be carcinogenic in various experimental animals under
differing routes of exposure. Epidemiologic studies present equivocal conclu-
sions on the carcinogenicity of beryllium and beryllium compounds. A lifetime
cancer risk for continuous inhalation exposure at 1 ng beryllium/m has been
estimated.
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TABLE OF CONTENTS
Page
LIST OF TABLES ix
LIST OF FIGURES x
1. INTRODUCTION 1-1
2. SUMMARY AND CONCLUSIONS 2-1
2.1 BACKGROUND INFORMATION 2-1
2.2 BERYLLIUM METABOLISM 2-1
2.3 BERYLLIUM TOXICOLOGY 2-2
2.3.1 Subcellular and Cellular Aspects of Beryllium
Toxicity 2-2
2.3.2 Pulmonary and Systemic Toxicity of Beryllium in
Man and Animals 2-3
2.3.3 Dermatological Effects of Beryllium Exposure 2-5
2.3.4 Teratogenic and Reproductive Effects of Beryllium
Exposure 2-5
2.4 MUTAGENIC EFFECTS OF BERYLLIUM EXPOSURE 2-5
2.5 CARCINOGENIC EFFECTS OF BERYLLIUM EXPOSURE 2-6
2.5.1 Animal Studies 2-6
2. 5. 2 Human Studies 2-6
2.5.3 Qualitative Carcinogenicity Conclusions 2-7
2.6 HUMAN HEALTH RISK ASSESSMENT OF BERYLLIUM 2-7
2.6.1 Exposure Aspects 2-7
2.6.2 Relevant Health Effects 2-7
2.6.3 Dose-Effect and Dose-Response Relationships of
Beryl 1 i urn 2-8
2.6.4 Populations at Risk 2-9
3. BERYLLIUM BACKGROUND INFORMATION 3-1
3.1 GEOCHEMICAL AND INDUSTRIAL BACKGROUND 3-1
3.1.1 Geochemistry of Beryllium 3-1
3.1.2 Production and Consumption of Beryllium Ore 3-2
3.2 CHEMICAL AND PHYSIOCHEMICAL PROPERTIES OF BERYLLIUM 3~3
3.3 SAMPLING AND ANALYSIS TECHNIQUES FOR BERYLLIUM 3-5
3.4 ATMOSPHERIC EMISSIONS, TRANSFORMATION AND DEPOSITION 3-7
3.5 ENVIRONMENTAL CONCENTRATIONS OF BERYLLIUM 3-11
3.5.1 Ambient Air 3-11
3.5.2 Soils and Natural Waters 3-13
3.6 PATHWAYS TO HUMAN CONSUMPTION 3-13
4. BERYLLIUM METABOLISM IN MAN AND ANIMALS 4-1
4.1 ROUTES OF BERYLLIUM ABSORPTION 4-1
4.1.1 Beryllium Absorption by Inhalation 4-1
4.1.2 Gastrointestinal Absorption of Beryllium 4-2
4.1.3 Percutaneous Absorption of Beryllium 4-3
4.1.4 Transplacental Transfer of Beryllium 4-3
4.2 TRANSPORT AND DEPOSITION OF BERYLLIUM IN MAN AND
EXPERIMENTAL ANIMALS 4-4
4.3 EXCRETION OF BERYLLIUM IN MAN AND ANIMALS 4-5
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TABLE OF CONTENTS (continued)
Page
5. BERYLLIUM TOXICOLOGY 5-1
5.1 ACUTE EFFECTS OF BERYLLIUM EXPOSURE IN MAN AND ANIMALS 5-1
5.1.1 Human Studies 5-1
5.1.2 Animal Studies 5-2
5.2 CHRONIC EFFECTS OF BERYLLIUM EXPOSURE IN MAN AND ANIMALS 5-2
5.2.1 Respiratory and Systemic Effects of Beryllium 5-2
5.2.1.1 Human Studies 5-2
5.2.1.2 Animal Studies 5-13
5.2.2 Teratogenic and Reproductive Effects of Beryllium ... 5-17
5.2.2.1 Human Studies 5-17
5.2.2.2 Animal Studies 5-17
6. MUTAGENIC EFFECTS OF BERYLLIUM 6-1
6.1 GENE MUTATIONS IN BACTERIA AND YEAST 6-1
6.1.1 Salmonella Assay 6-1
6.1.2 Host-mediated Assay 6-1
6.1.3 Escherichia coli WP2 Assay 6-3
6.2 GENE MUTATIONS IN CULTURED MAMMALIAN CELLS 6-3
6.3 CHROMOSOMAL ABERRATIONS 6-5
6.4 SISTER CHROMATID EXCHANGES 6-5
6.5 OTHER TESTS OF GENOTOXIC POTENTIAL 6-7
6.5.1 The Rec Assay 6-7
6.5.2 PpJ_ Assay 6-7
6.5.3 Hepatocyte Primary Culture/DNA Repair Test 6-8
6.5.4 Beryllium-Induced DNA Cell Binding 6-8
6.5.5 Mitotic Recombination in Yeast 6-9
6.5.6 Biochemical Evidence of Genotoxicity 6-9
6.5.7 Mutagenicity Studies in Whole Animals 6-9
7. CARCINOGENIC EFFECTS OF BERYLLIUM 7-1
7.1 ANIMAL STUDIES 7-1
7.1.1 Inhalation Studies 7-1
7.1.2 Intratracheal Injection Studies 7-7
7.1.3 Intravenous Injection Studies 7-11
7.1.4 Intramedullary Injection Studies 7-14
7.1.5 Intracutaneous Injection Studies 7-15
7.1.6 The Percutaneous Route of Exposure 7-15
7.1.7 Dietary Route of Exposure 7-15
7.1.8 Tumor Type, Species Specificity, Carcinogenic
Forms, and Dose-Response 7-16
7.1.8.1 Tumor Type and Proofs of Malignancy 7-16
7.1.8.2 Species Specificity and Immunobiology 7-17
7.1.8.3 Carcinogenic Forms and Dose-Response
Relationships 7-18
7.1.9 Summary of Animal Studies 7-20
7.2 EPIDEMIOLOGIC STUDIES 7-24
7.2.1 Bayliss et al. (1971) 7-24
7.2.2 Bayliss and Lainhart (1972, unpublished) 7-25
7.2.3 Bayliss and Wagoner (1977, unpublished) 7-26
7.2.4 Wagoner et al. (1980) 7-27
vi
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TABLE OF CONTENTS (continued)
7.2.5 Infante et al. (1980) 7-32
7.2.6 Mancuso and El-Attar (1969) 7-36
7.2.7 Mancuso (1970) 7-36
7.2.8 Mancuso (1979) 7-38
7.2.9 Mancuso (1980) 7-41
7.2.10 Summary of Epidemiologic Studies 7-44
7.3 QUANTITATIVE ESTIMATION 7-48
7.3.1 Procedures for the Determination of Unit Risk 7-50
7.3.1.1 Low-Dose Extrapolation Model 7-50
7.3.1. 2 Selection of Data 7-52
7.3.1.3 Calculation of Human Equivalent Dosages .... 7-53
7.3.1.3.1 Oral Exposure 7-53
7.3.1.3.2 Inhalation Exposure 7-55
7.3.1.4 Calculation of the Unit Risk from Animal
Studies 7-57
7.3.1.4.1 Adjustments for Less Than
Lifespan Duration of Experi-
ment 7-57
7.3.1.5 Model for Estimation of Unit Risk Based
on Human Data 7-58
7.3.2 Estimation of the Carcinogenic Risk of Beryllium 7-59
7.3.2.1 Calculation of the Carcinogenic Potency
of Beryllium on the Basis of Animal
Data 7-59
7.3.2.2 Calculation of the Carcinogenic Potency
of Beryllium on the Basis of Human
Data 7-60
7.3.2.2.1 Information on Exposure
Levels 7-62
7.3.2.2.2 Information on Excess Risk 7-63
7.3.2.3 Risk Due to Exposure to 1 ug/ms of
Beryl 1 iurn in Air 7-65
7.3.3 Comparison of Potency With Other Compounds 7-66
7.3.4 Summary of Quantitative Assessment 7-72
7.4 SUMMARY 7-73
7.4.1 Qualitative Summary 7-73
7.4.2 Quantitative Summary 7-74
7.5 CONCLUSIONS 7-75
8. HUMAN HEALTH RISK ASSESSMENT FOR BERYLLIUM 8-1
8.1 AGGREGATE HUMAN INTAKE OF BERYLLIUM 8-1
8.2 SIGNIFICANT HEALTH EFFECTS OF BERYLLIUM FOR HUMAN RISK
ASSESSMENT 8-1
8.3 DOSE-EFFECT AND DOSE-RESPONSE RELATIONSHIPS OF BERYLLIUM .... 8-2
8.4 POPULATIONS AT RISK 8-5
9. REFERENCES 9-1
Vll
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TABLE OF CONTENTS (continued)
Page
APPENDIX A—Analysis of Incidence Data with Time-dependent
Dose Pattern A-l
APPENDIX IB—International Agency for Research on Cancer
Criteria for Evaluation of the Carcinogenicity of
Chemicals B-l
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LIST OF TABLES
Page
3-1 Production and Consumption of Beryllium Ore 3-2
3-2 Physical Properties of Beryllium and Related Metals 3-4
3-3 Industrial Uses of Beryllium Products 3-6
3-4 Natural and Anthropogenic Emissions of Beryllium 3-8
3-5 Concentrations of Beryllium in Urban Atmospheres 3-12
3-6 Potential Human Consumption of Beryllium from Normal
Sources in a Typical Residential Environment 3-16
5-1 Beryllium Registry Cases, 1959 5-4
5-2 Time from Last Exposure to First Symptom in the BCR, 1959 ... 5-4
5-3 Changes of Latency from 1922 to Present in Occupational
Beryl!iosis Cases 5-7
5-4 Symptoms of Chronic Beryllium Disease 5-7
5-5 Signs of Chronic Beryllium Disease 5-8
5-6 Comparison of 1971 and 1974 Data of Workers Surveyed in
Beryllium Extraction and Processing Plants 5-11
5-7 Comparison of 1971 and 1974 Arterial Blood Gas Results 5-11
6-1 Mutagenicity Testing of Beryllium: Gene Mutations
in Bacteria and in Yeast 6-2
6-2 Mutagenicity Testing of Beryllium: Gene Mutations
in Mammalian Cells In Vitro 6-4
6-3 Mutagenicity Testing of Beryllium: Mammalian _In Vitro
Cytogenetics Tests 6-6
7-1 Pulmonary Carcinoma from Beryllium Part 2 7-3
7-2 Pulmonary Carcinoma from Beryllium Part 1 7-4
7-3 Beryllium Alloys -- Lung Neoplasms 7-9
7-4 Lung Tumor Incidence in Rats Among BeO, As203 and Control
Groups 7-10
7-5 Histological Classification of Lung Tumors and Other
Pathological Changes 7-10
7-6 Osteogenic Sarcomas in Rabbits 7-12
7-7 Osteosarcoma from Beryllium 7-13
7-8 Carcinogenicity of Beryllium Compounds 7-21
7-9 Comparison of Study Cohorts and Subcohorts of Two
Beryllium Companies 7-45
7-10 Problems with Beryllium Cohort Studies 7-47
7-11 Beryllium Dose-Response Data from Seven Inhalation Studies
on Rats, and the Corresponding Potency (Slope) Estimations .. 7-61
7-12 Observed/Expected Lung Cancer Deaths (Relative Risk)
Among White Male Workers Who Were Employed at Least
15 Years Ago at the End of Follow-up 7-64
7-13 Cancer Potency Estimates Calculated Under Various
Assumptions 7-65
7~14 Relative Carcinogenic Potencies Among 53 Chemicals
Evaluated by the Carcinogen Assessment Group as Suspect
Human Carcinogens 7-68
A-l Time-to-Death Data A-2
ix
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LIST OF FIGURES
Figure Page
3-1 Pathways of Environmental Beryllium Concentrations
Leadi ng to Potenti al Human Exposure 3-14
5-1 Latency According to Year of First Exposure (Occupational
Berylliosis) 5-6
7-1 Pulmonary Tumor Incidence in Female Rats, 1965-1967 7-6
7-2 Histogram Representing the Frequency Distribution of the
Potency Indices of 53 Suspect Carcinogens Evaluated by
the Carcinogen Assessment Group 7-67
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AUTHORS AND REVIEWERS
The authors of this document are:
Dr. Robert Elias
Environmental Criteria and Assessment Office
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina
Dr. Kantharajapura S. Lavappa
Reproductive Effects Assessment Group
U.S. Environmental Protection Agency
Washington, D.C.
Dr. Magnus Piscator
Karolinska Institute
Stockholm, Sweden
Dr. Andrew L. Reeves
Wayne State University
Detroit, Michigan
Dr. Carol Sakai
Reproductive Effects Assessment Group
U.S. Environmental Protection Agency
Washington, D.C.
Carcinogen Assessment Group
U.S. Environmental Protection Agency
Washington, D.C.
Participating members of the CAG are listed below:
(Principal authors and contributors to carcinogenicity sections of this document
are designated by *).
Roy Albert, M.D. (Chairman)
Elizabeth Anderson, Ph.D.
Larry D. Anderson, Ph.D.
Steven Bayard, Ph.D.
David Bayliss, M.S.*
Chao W. Chen, Ph.D.*
Margaret Chu, Ph.D.*
Herman J. Gibb, M.S., M.P.H.
Bernard H. Haberman, D.V.M., M.S.
Charalingayya B. Hiremath, Ph.D.
Robert McGaughy, Ph.D.
Dharm V. Singh, D.V.M., Ph.D.
Todd W. Thorslund, Sc.D.
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Project Manager:
Ms. Donna J. Sivulka
Environmental Criteria and Assessment Office
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina
The following individuals reviewed earlier drafts of this document and sub-
mitted valuable comments:
Dr. Frank D'ltri
Michigan State University
East Lansing, Michigan
Dr. Philip Enterline
University of Pittsburgh
Pittsburgh, Pennsylvania
Dr. Jean French
Center for Disease Control
Atlanta, Georgia
Dr. Richard Henderson
Health Sciences Consultants
Osterville, Massachusetts
Dr. Marshall Johnson
Thomas Jefferson Medical College
Philadelphia, Pennsylvania
Dr. Magnus Piscator
Karolinska Institute
Stockholm, Sweden
Dr. Neil Roth
Roth and Associates
Rockville, Maryland
Dr. Flo Ryer
Exposure Assessment Group
U.S. Environmental Protection Agency
Washington, D.C.
Dr. Carl Shy x
University of North Carolina
Chapel Hill, North Carolina
Dr. Vincent Simmon
Genex Corporation
Gaithersburg, Maryland
Dr. F. William Sunderman, Jr.
University of Connecticut
Farmington, Connecticut
xii
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Dr. J. Jaroslav Vostal
General Motors Research Laboratory
Warren, Michigan
Dr. John Wood
University of Minnesota
Navarre, Minnesota
In addition, there are several scientists who contributed valuable information
and/or constructive criticism to interim drafts of this report. Of specific
note are the contributions of: Jack Behm, Richard Chamber!in, Thomas J.
Concannon, John Copeland, Bernie Greenspan, Si Duk Lee, Brian MacMahon,
Robert J. McCunney, Ray Morrison, Om Mukheja, Chuck Nauman, Martin B. Powers,
and Otto Preuss.
Technical Assistance
Project management, editing, production, word processing and workshop from
Northrop Services, Inc., under contract to the Environmental Criteria and
Assessment Office:
Ms. Barbara Best-Nichols
Ms. Linda Cooper
Dr. Susan Dakin
Ms. Anita Flintall
Ms. Kathryn Flynn
Ms. Miriam Gattis
Ms. Tami Jones
Ms. Varetta Powell
Ms. Patricia Tierney
Word processing and other technical assistance at the Office of Health and
Environmental Assessment:
Ms. Linda Bailey
Ms. Frances P. Bradow
Ms. Diane Chappell
Ms. Renee Cook
Mr. Doug Fennel 1
Mr. Allen Hoyt
Ms. Barbara Kearney
Ms. Emily Lee
Ms. Marie Pfaff
Ms. Judy Theisen
Ms. Donna Wicker
xn i
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1. INTRODUCTION
This report evaluates health effects associated with beryllium exposure,
with particular emphasis placed on effects thought to be of most concern to
the general U.S. population.
This report is organized into chapters which provide a cohesive discus-
sion of all aspects of beryllium and delineate a logical linking of this
information to human health risk. The chapters include: an executive summary
(Chapter 2) of the information contained within the text of later chapters;
background information on the chemical and environmental aspects of beryllium,
including levels of beryllium in media with which U.S. population groups come
into contact (Chapter 3); beryllium metabolism, where factors of absorption,
biotransformation, tissue distribution, and excretion of beryllium are dis-
cussed with reference to the element's toxicity (Chapter 4); beryllium toxi-
cology, discussing the various acute, subacute, and chronic health effects of
beryllium in man and animals (Chapter 5); beryllium mutagenesis, discussing
the ability of beryllium to cause gene mutations, chromosomal aberrations and
sister chromatid exchanges (Chapter 6); beryllium carcinogenesis, including
discussion of selected dose-effect and dose-response relationships (Chapter 7);
and a human health risk assessment for beryllium, where key information from
the preceding chapters is placed in an interpretive and quantitative perspec-
tive highlighting those health effects likely of most concern for U.S. popula-
tions (Chapter 8).
This report is not intended to be an exhaustive review of all the beryllium
literature, but is focused upon those data thought to be most useful and
relevant for human health risk assessment purposes. Particular emphasis is
placed on delineation of health effects and risks associated with exposure to
airborne beryllium, in view of the most immediate use intended for the present
report, i.e., to serve as a basis for decision making regarding the regulation
of beryllium as a hazardous air pollutant under pertinent sections of the
Clean Air Act, as amended in 1977. Health effects associated with the inges-
tion of beryllium or with exposure via other routes are also discussed, pro-
viding a basis for possible use for multimedia risk assessment purposes, as
well. The background information provided at the outset on sources, emissions,
and ambient concentrations of beryllium in various media is presented in order
to provide a general perspective against which to view the health effects eval-
uations contained in later chapters of the document. More detailed exposure
1-1
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assessments, taking into account even more recent, up-to-date emission and
ambient concentration data will be prepared separately for use in subsequent
EPA regulatory decision making regarding beryllium.
1-2
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2. SUMMARY AND CONCLUSIONS
2.1 BACKGROUND INFORMATION
Even though industrial consumption of beryllium has increased 10-fold in
the last 40 years, there has been no detectable change in environmental concen-
trations of beryllium. The primary source of atmospheric beryllium is from
the combustion of coal, although the emission factors from this source are
subject to controversy.
Contamination of the natural environment is largely by atmospheric deposi-
tion, as the production of solid beryllium waste appears to be negligible.
Beryllium from the atmosphere eventually reaches the soil or sediments where
it is probably retained in the relatively insoluble form of beryllium oxide at
very low concentrations. In two hundred years since the industrial revolution,
it is likely that no more than 0.1 ug Be/g has been added to the very surface
of the soil, which has a natural beryllium concentration of 0.6 M9/9- Distri-
buted evenly throughout the soil column, atmospheric beryllium could account
for less than 1 percent of the total soil beryllium. Allowing for greater
mobility of atmospheric beryllium in soil than natural beryllium in the inor-
ganic soil fraction, it is possible that 10 to 50 percent of the beryllium in
plants and animals may be of anthropogenic origin.
Contamination of the human environment also appears to be by the atmos-
pheric route, as there appear to be no sources of industrial beryllium immedi-
ately influencing human consumption, except in a primary or secondary occupa-
tional setting. The normal consumption of beryllium is probably about 400 to
450 ng/day, of which 50 to 90 percent may be natural.
2.2 BERYLLIUM METABOLISM
The main routes of beryllium intake for man and animals are inhalation
and ingestion. Percutaneous absorption is insignificant.
Due to the specific chemical properties of beryllium compounds, even
primarily soluble beryllium compounds are partly transformed to more insoluble
forms in the lungs, resulting in long retention times after exposure to all
types of beryllium compounds in the lungs. Like other particulates, dose and
particle size are decisive factors for the deposition and clearance of inhalec
beryllium particles. Of the deposited beryllium that is absorbed, part will
be rapidly excreted and part will be stored in bone.
2-1
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Some beryllium is transferred to the regional lymph nodes. Beryllium trans-
ferred from the lungs to the gastrointestinal tract is mainly eliminated via
feces with only a minor portion being absorbed.
There are no quantitative data on absorption of beryllium from the gastro-
intestinal tract in human beings,"but several animal studies indicate that the
absorption of ingested beryllium is less than 1 percent.
The absorption of beryllium through intact skin is very small, as beryllium
is tightly bound in the epidermis.
Absorbed beryllium will go into the blood, but there are no data on the
partitioning of beryllium between plasma and erythrocytes. In plasma, there
are limited data suggesting that at normally occurring levels of beryllium,
the main binding is to some plasma proteins. In animal experiments, it has
been shown that large doses of injected beryllium are found in aggregates
bound to phosphate. The smaller the dose, the more beryllium will be in the
diffusible form. There are not enough data to permit an estimate of the
levels of beryllium normally occurring in blood or plasma.
The tissue distribution of absorbed beryllium is characterized by main
depositions in the skeleton, with other organs containing very low levels. In
the liver, beryllium seems to be preferentially taken up by lysosomes. There
are not enough data to permit any conclusions about the normal distribution
and amounts of beryllium in the human body. The total body burden is probably
less than 50 ug.
Based on animal studies, beryllium appears to have a long biological
half-time, mainly depending on its storage in the skeleton. The half-time in
soft tissues is relatively short.
Beryllium seems to be normally excreted in very small amounts via urine,
normal levels in human urine probably being only a few nanograms per liter.
Animal data indicate that some excretion via the gastrointestinal tract may
occur.
2.3 BERYLLIUM TOXICOLOGY
2.3.1 Subcellular and Cellular Aspects of Beryllium Toxicity
It is not well known in what form or through which mechanism beryllium is
bound to tissue constituents in normal human beings. Beryllium can bind to
lymphocyte membranes, which may explain the sensitizing properties of the metal.
A number of reports on experimental studies describe various J_n vivo and i_n
vitro effects of various beryllium compounds on enzyme systems, especially
2-2
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alkaline phosphatase, to which beryllium can bind. Effects on protein and
nucleic acid metabolism have been shown in many experimental studies; however,
the doses in these studies have been large and parenterally administered.
Because such administrative routes have little practical application to humans,
the data from these studies have little utility in advancing an understanding
of human effects, which are mainly on the lung. In the lung, retained beryllium
particles are found in the macrophages, and the understanding of how these and
other pulmonary cells metabolize beryllium is probably of most relevance for
understanding chronic beryllium disease.
An important aspect of beryllium toxicology is that beryllium can cause
hypersensitivity which is essentially cell-mediated. There are species differ-
ences; thus, humans and guinea pigs can be sensitized to beryllium, whereas
the present data indicate that no such mechanism exists in the rat. Earlier,
patch tests were used to detect hypersensitivity in humans, but these tests
are no longer used since they were shown to cause a reactivation of latent
beryllium disease. Presently, the lymphoblast transformation is regarded as
the most useful test to detect hypersensitivity to beryllium.
2.3.2 Pulmonary and Systemic Toxicity of Beryllium in Man and Animals
There are no data indicating that moderate beryllium exposure via oral
administration causes any local or systemic effects in human beings or in
animals. Respiratory effects, possibly combined with systemic effects, con-
stitute the major health effects of concern in beryllium exposures, with
hypersensitization likely playing an important role in the manifestation of
the systemic effects. Respiratory effects may occur as either a nonspecific
acute disease or as a more specific chronic beryllium disease.
The most acutely toxic beryllium compounds are probably beryllium oxides
fired at low temperatures, e.g. 500°C, and some salts, such as the fluoride
and the sulfate. The latter forms of beryllium are acidic, and part of the
toxic reactions caused by these compounds may be due to the acidity of the
particles. Acute effects have generally occurred at concentrations above
3
100 ug/m of beryllium, and the main feature of such effects is a chemical
pneumonitis which may lead to pulmonary edema and even death. In animal
experiments, concentrations of more than 1 mg/m have generally been needed to
produce acute effects, but effects have been reported at lower levels of
exposure. In most cases, the acute disease will regress, but it may take
several weeks or months before recovery is complete. If there is no further
2-3
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excessive exposure to beryllium, it is generally believed that acute disease
will not lead to chronic beryllium disease. The amount initially deposited
during acute exposure and individual predisposition are probably the main
factors leading to later sequelae.
Acute beryllium poisoning was quite common in the 1940's, but since the
present standards were established in 1949, the number of new cases reported
has been relatively small.
Chronic beryllium disease occurred as an epidemic in the 1940's, which
led to the establishment of the "Beryllium Case Registry" (BCR), a file for
all cases of acute and chronic beryllium disease. Chronic beryllium disease
is characterized by dyspnea, cough, and weight loss, and sometimes is associ-
ated with systemic effects in the form of granulomas in skin and muscles and
effects on calcium metabolism. There are many similarities between chronic
beryllium disease and sarcoidosis, but in sarcoidosis the systemic effects are
much more predominant than in chronic beryllium disease. In most cases of
chronic beryllium disease there are only lung effects without systemic involve-
ment. Pathologically, the disease is a granulomatosis in which eventually
there may be fibrosis, emphysema and also cor pulmonale. Resultant deaths
from chronic beryllium disease are often due to cor pulmonale. A long latency
time is typical to the appearance of the disease; sometimes there may be more
than 20 years between last exposure and the diagnosis of the disease.
It has been very difficult to establish the levels of beryllium in air
that may cause the disease. One reason for this difficulty is that exposure
data have not always been obtainable. Another factor is that hypersensitization
may cause the occurrence of the disease in people with relatively low exposures,
whereas in nonsensitized people with much higher exposures there may be no
effects. Diagnosis of the disease is obtained by X-ray examinations, but lung
function tests of vital capacity may decrease before roentgenological changes
are seen.
There are limited data on levels of beryllium found in the tissue of lung
in cases of acute and chronic beryllium disease, and these data do not allow
for conclusions about dose-effect relationships.
New cases of chronic beryllium disease are still being reported due to
the fact that, in some instances, the standards have been exceeded. In indus-
tries, where the average exposure generally has been below 2 ug/m , there have
been very few new cases of chronic beryllium disease. It is conceivable that
3
peak exposures in such cases have exceeded 25 ug/m .
2-4
-------
There have also been a large number of "neighborhood" beryllium disease
cases reported. Neighborhood cases are those in which chronic beryllium
disease occurs in people living in the vicinity of beryllium-emitting plants.
The air concentrations of beryllium in such areas at the time when the disease
has occurred has probably been around 0.1 ug/m , but considerable exposure via
dust transferred to homes from the plants likely contributed to the occurrence
of the disease. No new "neighborhood" cases of beryllium disease have occurred
3
since standards of 0.01 pg/m were set for ambient air. Present ambient air
3
levels are generally below 1 ng/m .
2.3.3 Dermatological Effects of Beryllium Exposure
Contact dermatitis and some other dermatological effects of beryllium
have been documented in occupationally exposed persons, but there are no data
indicating that such reactions have occurred, or may occur, in the general
population.
2.3.4 Teratogenic and Reproductive Effects of Beryllium Exposure
Available information on the teratogenic or reproductive effects of
beryllium exposure is limited to three animal studies. The information from
these studies is not sufficient to determine whether beryllium compounds have
the potential to produce adverse reproductive or teratogenic effects. Further
studies are needed in this area.
2.4 MUTAGENIC EFFECTS OF BERYLLIUM EXPOSURE
Beryllium has been tested for its ability to cause gene mutations in
Salmonella typhimurium, Escherichia coli, yeast, and cultured human lymphocytes
and Syrian hamster embryo cells; DNA damage in Escherichia coli and unscheduled
DNA synthesis in rat hepatocytes.
Beryllium sulfate and beryllium chloride have been shown to be nonmutagenic
in all bacterial and yeast gene mutation assays. This is because bacterial
and yeast systems have proven to be insensitive for the detection of metal
mutagens in general. Gene mutation studies in cultured mammalian cells,
Chinese hamster V79 cells and Chinese hamster ovary (CHO) cells, on the other
hand, have yielded positive mutagenic responses of beryllium. Similarly,
chromosomal aberration and sister chromatid exchange studies in cultured human
lymphocytes and Syrian hamster embryo cells have also resulted in positive
2-5
-------
mutagenic responses of beryllium. In DMA damage and repair assays, beryllium
was negative in pol, rat hepatocyte, and mitotic recombination assays, but was
weakly positive in the rec assay. Based on the information so far available,
beryllium appears to have the potential to cause mutations.
2.5 CARCINOGENIC EFFECTS OF BERYLLIUM EXPOSURE
2.5.1 Animal Studies
Experimental beryllium carcinogenesis has been successfully induced by
intravenous or intramedullary injection of rabbits, and by inhalation exposure
or intratracheal injection of rats. The carcinogenic evidence for mice (intra-
venously injected) and monkeys and rabbits (intratracheally injected or exposed
via inhalation) is presently uncertain. Guinea pigs, and possibly hamsters,
have not been shown to be susceptible to beryllium carcinogenesis.
In rabbits, osteosarcomas and chondrosarcomas have been induced. These
tumors have been highly invasive, metastasize readily, and are judged to be
histologically similar to corresponding human tumors. In rats, pulmonary
adenomas and/or adenocarcinomas of questionable malignancy have been obtained,
although these studies are not well documented.
Although some studies involving beryllium clearly have limitations, the
totality of the data, using the criteria of the International Agency for
Research on Cancer (IARC), requires that beryllium be placed in the "sufficient
evidence" category of animal carcinogens.
2.5.2 Human Studies
Epidemiologic studies present equivocal conclusions on the carcinogenicity
of beryllium and beryllium compounds. Early studies (see IARC, 1972, 1980;
Bayliss et al., 1971; Bayliss and Lainhart, 1972) did not provide positive
evidence, but a few recent studies indicate an increased risk of lung cancer
in beryllium-exposed workers. In general, the absence of beryllium exposure
levels and the information on other possible confounding factors within the
workplace make a positive correlation between beryllium exposure and increased
risk of cancer difficult to substantiate. Epidemiologic evidence must therefore
be classified as "limited" to "inadequate" according to the IARC criteria for
determining carcinogenicity.
2-6
-------
2.5.3 Qualitative Carcinogenicity Conclusions
Overall, the animal and human evidence for carcinogenicity is considered
to be either in IARC Group 2A or 2B depending upon the interpretation given to
the human studies. A Group 2A or 2B classification under IARC criteria means
that the chemical or chemicals are probably carcinogenic for humans.
2.6 HUMAN HEALTH RISK ASSESSMENT OF BERYLLIUM
2.6.1 Exposure Aspects
In the general population, the dietary intake of beryllium is probably
several micrograms but the absorbed amount will probably be extremely low due
to the chemical properties of beryllium. Very little beryllium will be avail-
able in the gut for absorption. The daily inhaled amount will, for most
people, probably be only a few nanograms, but it can be expected that most of
the beryllium inhaled will be retained in the lungs and will eventually accumu-
late. The available data on levels of beryllium in the lung indicate that the
lung burden in adults may be around 1 to 10 p.g. The small amounts of beryllium
absorbed will go to the skeleton. Since beryllium occurs in cigarettes it can
be expected that smokers will absorb and retain more beryllium than nonsmokers.
However, the present data on beryllium in mainstream smoke are contradictory.
2.6.2 Relevant Health Effects
Occupational exposure to various beryllium compounds has been associated
with acute respiratory disease and chronic beryllium disease in the form of
granulomatosis. Some systemic effects have also been noted and a hypersensi-
tization component probably plays a major role in the manifestation of these
effects. In the past, chronic beryllium disease was found in members of the
general population living near beryllium-emitting plants, but past exposures
were high compared to present levels of beryllium in the ambient air. No
"neighborhood" cases of chronic beryllium disease have been reported in the
past several years.
Numerous animal studies have been performed to determine whether or not
beryllium and beryllium-containing substances are carcinogenic. Although some
of these studies have limitations, the overall evidence from animal studies
should be classified as "sufficient" using the evaluation criteria of the
International Agency for Research on Cancer (IARC). The IARC has also con-
cluded that the evidence from animal studies is "sufficient." Human studies
2-7
-------
on beryllium carcinogenicity have deficiencies that limit any definitive conclu-
sion that a true association exists. Nevertheless, the possibility exists
that a portion of the excess cancer risks reported in these studies may, in
fact, be due to beryllium exposure. Although IARC concluded that beryllium
and its compounds should be classified as having "limited" human evidence ,of
carcinogenicity, the U.S. Environmental Protection Agency's Carcinogen Assess-
ment Group (CAG) has concluded that the evidence can be considered as being
"limited" to "inadequate."
2.6.3 Dose-Effect and Dose-Response Relationships of Beryllium
As previously stated, there are two components of chronic beryllium
disease. One is a more direct toxic effect of beryllium on the lung tissue,
and the other is the hypersensitization factor. Even if exposure data of high
quality were available, it would still be difficult to establish dose-effect
and dose-response relationships due to this hypersensitization factor. Present
experience indicates that no adverse effects have been noted in industries
3
where adherence to the 2 (jg/m standard has been maintained; thus, that level
of beryllium in air seems to provide good protection in regard to noncarcino-
genic effects. To what extent peak exposures above the present standard of
3 3
2 |jg/m , i.e., up to 25 pg/m , may cause delayed effects is not clear.
From available data, the CAG has estimated carcinogenic unit risks for
air exposure to beryllium. The quantitative aspect of carcinogen risk assess-
ment is included here because it may be of use in setting regulatory priori-
ties and in evaluating the adequacy of technology-based controls and other
aspects of the regulatory decision-making process. However, the uncertainties
associated with estimated cancer risks to humans at low levels of exposure
should be recognized. At best, the linear extrapolation model used (see
Section 7.3) provides a rough but plausible estimate of the upper limit of
risk—that is, it is not likely that the true risk would be much higher than
the estimated risk, but it could be considerably lower. The risk estimates
presented below should not be regarded, therefore, as accurate representations
of true cancer risks even when the exposures involved are accurately defined.
The estimates presented may, however, be factored into regulatory decisions to
the extent that the concept of upper-risk limits is found to be useful.
Both animal and human data are used to estimate the carcinogenic potency
of beryllium. Most of the animal inhalation studies conducted on beryllium
2-8
-------
are not well documented, were conducted only at single dose levels, and did
not utilize control groups. In the present report, data from eight rat studies
were used to estimate the upper bounds for the carcinogenic potency of beryl-
lium. The upper-bound potency estimates, calculated on the basis of animal
_o o o
data, range from 2.9 x 10 /(ug/m) to 4.4/(|jg/m ). Among the four beryllium
compounds examined in the eight studies, beryl ore is the least carcinogeni-
cally potent, while beryllium sulfate is the most potent. The estimated
potency values for beryllium on the basis of animal studies, except the potency
value estimated with the Wagner et al. (1980) study on beryl ore, are consider-
ably greater than those estimated from human data. In light of the human
experience in the beryllium industries, the risk estimates from animal data do
not appear to be reasonable. Therefore, information from two epidemiologic
studies by Mancuso (1979) and Wagoner et al. (1980) and the industrial hygiene
reviews by NIOSH (1972) and Eisenbud and Lisson (1983) have been used to
estimate the plausible upper bound for incremental cancer risks associated
with exposure to air contaminated with beryllium. The upper-bound incremental
lifetime cancer risk associated with 1 ug/m of beryllium in the air is esti-
mated to be 7.4 x 10 . This incremental unit risk estimate places the relative
carcinogenic potency of beryllium in the lower part of the third quartile of
the 53 suspect carcinogens evaluated by the CAG.
2.6.4 Populations at Risk
In terms of exposure, persons engaged in handling beryllium in occupa-
tional environments obviously comprise individuals at highest risk. With
regard to the population at large, there may be a small risk for people living
near beryllium-emitting industries. However, the risk for such individuals
may not be due so much to ambient air levels of beryllium, but rather due to
the possibility of accumulated beryllium-contaminated dust within the household.
There are no data that allow an estimate of the number of people that may be
at such risk, but it is reasonable to assume that it is a very small group.
It should be noted that no new "neighborhood" cases of beryllium disease have
been reported since the 1940's.
2-9
-------
3. BERYLLIUM BACKGROUND INFORMATION
3.1 GEOCHEMICAL AND INDUSTRIAL BACKGROUND
3.1.1 Geochemistry of Beryllium
Average crustal rock contains about 2.8 pg Be/g (Mason, 1966). The
element occurs in more concentrated form as a component of over forty differ-
ent minerals. Granites are enriched by 15 to 20 ug Be/g. It is likely that
most beryllium minerals were formed during the cooling of granitic magmas
(Beus, 1966), where the element was excluded during the early cooling stages
and accumulated in the crystallization products of the final stages most
commonly in association with quartz. The most highly enriched deposits of
beryllium are found in pegmatitic intrusions.
Only two beryllium minerals are of current economic importance. Beryl,
an aluminosilicate (BesA^SigOg), is mined in the USSR, Brazil, Argentina, and
the People's Republic of China, for the most part, with smaller amounts produced
in several central African countries. Formed by pegmatite processes, beryl is
5- to 11-percent beryllium oxide and, in its purest gem quality form, is
treasured as the green or blue emerald. Until the late 1960s, the common
technique for separating beryl from associated rock was to crush the rock and
hand pick the mineral crystals. By 1969, as major beryl deposits in the free
world became exhausted, mechanical flotation separation techniques were
developed, and a second mineral, bertrandite [Be.Sip07(OH)?], became economi-
cally important (Anonymous, 1980). Bertrandite occurs as very tiny silicate
granules with a beryllium oxide concentration of less than 1 percent. The
only active commercial deposit of bertrandite rests at Spor Mountain, Utah.
This domestic source accounts for about 85 percent of the United States con-
sumption of beryllium ore, the rest being imported from the several countries
listed in Table 3-1 (Bureau of Mines, 1982).
Beryllium was discovered by Vauquelin in 1798. The element was isolated
in metallic form in 1828 by Woehler and perhaps independently in the same year
by Bussy (Beus, 1966). It is a light grey, low-density metal with a high
melting point, exceptional resistance to corrosion, and the capacity to absorb
heat. With these properties, it is not surprising that the demand for beryl-
lium closely parallels the growth of the nuclear, aerospace and electronics
industries.
In the United States, beryllium ore is processed at Delta, Utah by Brush
Well man, Inc.
3-1
-------
TABLE 3-1. PRODUCTION AND CONSUMPTION OF BERYLLIUM ORE (METRIC TONS)
World production of beryl
Argentina
Brazil
Madagascar
Mozambique
People's Republic of China2
Portugal
Rwanda
South Africa, Republic of
U.S.S.R.2
Zimbabwe
World production of bertrandite1
U.S. consumption of beryllium ore1
1948
2590
55
1960
10
90
--
--
11
48
--
--
--
1415
1969
8717
562
3900
--
132
--
31
290
340
1360
98
--
""
1978
2850
24
802
12
--
--
--
63
4
1900
38
3365
4099
1981
3857
32
590
10
20
940
20
98
108
1970
10
5908
8012
Calculated as the equivalent in beryl to avoid disclosing company proprietary
data
2estimated
Source: U.S. Bureau of Mines (1982)
3.1.2 Production and Consumption of Beryllium Ore
From the ore, beryllium is extracted as the hydroxide, from which all
forms of the metal and its alloys can be made. The most useful products are
beryllium metal, beryllium oxide and beryllium-copper alloys. Its stiffness
to-weight ratio and high thermal conductivity make beryllium metal useful in
the space and aircraft industry. In the electronics industry, beryllium oxide
is used to dissipate heat away from thermally sensitive components. Beryllium-
copper alloys, which provide a combination of strength, electrical conductivity
and resistance to stress relaxation, are used extensively for electrical/
electronic switches, sockets, and connectors. The alloys are also non-magnetic.
Beryllium alloys are also used in the production of dental prostheses (Newland,
1982). Other beryllium alloys are especially valuable for their resistance to
oxidation or corrosion.
Although beryllium had been isolated as a metal in 1828, it was not until
the 1930s that Be-Cu alloys came into widespread use. In the initial global
search for beryllium, deposits of beryl known for gem production were exploited.
By 1932, geochemical techniques for locating deposits by chemical anomalies in
surrounding rock formations were used in the USSR (Goldschmidt and Peters,
3-2
-------
1932). Although the discipline of geochemistry was well established, the low
concentrations of beryllium in crustal rock taxed the analytical capabilities
of the geochemists, and projects met with little success. Deposits of beryl
remained the sole source of beryllium until 1969. Consumption of beryllium
increased from 1415 tons in 1948 to 8581 tons in 1968, a 600-percent increase
that was ten times the growth rate of any other common metal (Knapp, 1971).
During this period, the nuclear power industry had joined the aerospace and
electonics industries as a consumer of beryllium products (Anonymous, 1980).
Two countries, the USSR and the United States, had become the primary consumers
of beryllium ore and producers of beryllium products.
Worldwide production of beryl virtually disappeared in the Western world,
decreasing from 7300 tons in 1969 to 900 tons in 1981 (Table 3-1). Production
in the USSR and the People's Republic of China rose to about 2900 tons in
1981. After domestic production of bertrandite became economically feasible in
1969, bertrandite production rose to the equivalent of about 6000 tons of
beryl in 1981, although this mineral contains only one tenth the beryllium of
beryl. Bertrandite is mined only in the United States, although the search
continues for beryl and bertrandite deposits around the world. From a domestic
production of 6000 equivalent tons of beryl ore and the import of 2138 actual
tons, the United States produced 130 tons of contained beryllium in 1981, of
which about 40 tons were exported as finished or unfinished products.
3.2 CHEMICAL AND PHYSIOCHEMICAL PROPERTIES OF BERYLLIUM
The chemical and geochemical properties of beryllium resemble those of
aluminum, zinc, and magnesium. Chemical similarities are due primarily to
similar ionic potentials, which facilitate covalent bonding (Novoselova and
Batsanova, 1969).
The chemistry of beryllium should be considered in the context of the
three most common forms of potential industrial emissions: the metal, the
oxide and the hydroxide (Table 3-2). In specific occupational settings,
beryllium halides may also be important, but these are not sufficiently wide-
spread to merit extended discussion here.
Beryllium is extracted from ores as the hydroxide and shipped in this
form to commercial processing plants (Anonymous, 1980). The most common con-
centration process involves leaching of 20-mesh particles with sulfuric acid
and hydroxylating the beryllium sulfate with di-2-ethylhexylphosphate in
kerosene. The beryllium hydroxide salt is collected by filtration. The
process recovers about 80 percent of the beryllium in low-grade bertrandite ore.
3-3
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TABLE 3-2. PHYSICAL PROPERTIES OF BERYLLIUM AND RELATED METALS
Be Al Zn Mg
Metal
Atomic number
Atomic weight
Atomic radius
Valence 0
Ionic radius A
Density 25°C
Melting point
Boiling point
Thermal conductivity 100°
Electrical resistivity
H°nm • cm @ 20°C
Oxide
Formula
Molecular weight
Density
Melting point
Boiling point
Thermal conductivity 725°C
cal/sec • cm2 • °C/cm
4
9.012
1.40
2+
.35
1.85
1283°C
2970°C
.401
4.31
BeO
25.01
3.008
2530
3900
.111
13
26.98
1.82
3+
.51
2.7
660.4
2467
.573
2.65
A1203
101.96
3.965
2072
2980
30
65.38
1.53
2+
.74
7.14
419.58
907
1.12
5.916
ZnO
81.37
5.606
1975
—
12
24.31
1.72
2+
.66
1.74
648.8
1107
.376
4.45
MgO
40.31
3.58
2852
3600
Hydroxide
Formula
Molecular weight
Density
Solubility M/£
Decomposes to oxide at °C
Be(OH)2
43.01
0.8 x 10"4
250-300
A1(OH)3
78.00
2.42
300
Zn(OH)2
99.38
3.053
125
Mg(OH)2
58.33
2.36
350
From beryl, beryllium may be extracted by the Sawyer-Kjellgren process,
where the ore is melted at 1625°C and cooled quickly with water to form a
beryllium glass. The glass is dried and ground to 200-mesh powder, then
leached with sulfuric acid. Sodium hydroxide is used to convert the sulfate
to beryllium hydroxide. This process is also about 80-percent efficient but
is not effective with the low beryllium concentration in bertrandite ore.
A third process, the Copaux-Kawecki process, uses sodium ferric fluoride
to extract beryllium from low-grade, fine-grained ores at a 90-percent effi-
ciency. This process is no longer used in the United States and Europe, due to
the higher expense and to the toxicity of beryllium fluoride. Indeed, the
3-4
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first medical report of beryl!iosis in 1933 can be attributed to exposure to
beryllium fluoride at an extraction plant (Weber and Englehardt, 1933).
Waste materials from the production of the raw beryllium product can
result in elevated environmental concentrations of beryllium hydroxide and
lesser amounts of beryllium fluoride. These would be confined to the waste
facilities used by the only ore-processing plant in the United States, operated
by Brush Wellman at Delta, Utah. Conversion of the hydroxide to the oxide or
pure metal form takes place at Brush Wellman facilities in Delta, Utah and
Elmore, Ohio.
About 10 percent of the domestic beryllium hydroxide is used for the
production of pure beryllium metal in sheet, rod, or wire form. Since 1979,
Brush Wellman, Inc. has been the only free-world producer of beryllium metal
(Anonymous, 1980). The metal is milled to desired specifications at the user
facility, producing beryllium dust and scrap in the vicinity of machine shops.
Because of the high cost of the metal at this point, efficient recovery and
recycling of the metal receive a high priority.
Beryllium oxide (beryllia) production consumes about 15 percent of the
raw beryllium hydroxide in the production of high-technology ceramics that
have superior thermal conductivity, especially at high temperatures. These
products make good electrical insulators and have a high resistance to thermal
shock. The high melting point permits the use of beryllium oxide in rocket
nozzles and thermocouple tubing (Table 3-3).
The remaining 75 percent of beryllium hydroxide is used in the production
of alloys, primarily Be-Cu alloys. As a general rule, 2 percent beryllium in
a copper alloy with an array of other metals can markedly increase the strength,
endurance, and hardness of the alloy. Most applications are in the electronic
field, although specialized uses such as springs, wheels, and pinions serve an
indispensable industrial function. Kawecki-Berylco, Inc. at Reading, Pennsylvania,
and Brush Wellman at Elmore, Ohio are the major producers of beryllium alloys in
the United States.
3.3 SAMPLING AND ANALYSIS TECHNIQUES FOR BERYLLIUM
Trace amounts of beryllium occur in environmental samples at concentra-
tions of about 0.01 to 0.1 ng/m in air, 0.05 to 0.1 M9/9 in dust, 0.01 to 1.0
ng/g in surface waters, 0.3 to 6 pg/g in soil, and 0.01 ug/g in biological
materials. Some plants, such as hickory, may accumulate beryllium as much as
3-5
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TABLE 3-3. INDUSTRIAL USES OF BERYLLIUM PRODUCTS
Beryllium Metal
aircraft disc brakes
navigational systems
X-ray transmission windows
space vehicle optics and
instruments
aircraft/satellite structures
missile parts
Beryllium Oxide
high-technology ceramics
electronic heat sinks
electrical insulators
microwave oven components
gyroscopes
Beryllium Alloys
springs
electrical connectors and relays
pivots, wheels and pinions
plastic injection molds
nuclear reactor neutron
reflector
fuel containers
precision instruments
rocket propellents
heat shields
mirrors
nuclear weapons
military vehicle armor
rocket nozzles
crucibles
thermocouple tubing
laser structural components
precision instruments
aircraft engine parts
submarine cable housing
non-sparking tools
1 (jg/g dry weight (Newland, 1982). Consequently, the collection and pretreat-
ment of samples is determined by the capabilities of the method of analysis.
Two techniques, gas chromatography (GC) (Ross and Sievers, 1972) and atomic
absorption spectroscopy (AAS) (Owens and Gladney, 1975) appear to give the
best combination of sensitivity and sample handling efficiency. Colorimetry,
fluorometry, and emission spectrometry are occasionally used.
3-6
-------
Because of interfering substances and low environmental concentrations,
samples analyzed by atomic absorption spectroscopy and gas chromatography
require pretreatment. At high concentrations (500 pg/g), aluminum and silicon
interfere with beryllium analysis by AAS. Separation is by chelation and ex-
traction with an organic solvent. The limit of detection for the flame method
of AAS is 2 to 10 ng/ml, and 0.1 ng/ml for the fTameless method. Air samples
of a few cubic meters must be concentrated after extraction to a volume of
less than 1 ml to enter the detection range. The high-volume sampler normally
3
used in sampling networks collects in the range of 1.1 to 1.7 m /min and is
therefore more desirable in terms of sample size than a low-volume sampler
3
which collects at 0,001 m /min, or a cascade impactor at the same flowrate.
Normal concentrations of dust, water and biological materials are all at or
below the detection limits of flameless AAS, so that preconcentration by wet
digestion is required.
Ross and Sievers (1972) report a detection limit of less than 0.04 ng/m
in air analyzed by GC, making this method marginally acceptable for small
sample sizes. Extensive chemical digestion and extraction is required, how-
ever.
For any method, standard reference materials are available in the form of
fly ash, coal, orchard leaves, and bovine liver. Owens and Gladney (1975)
have reported the beryllium values for these SRM's.
3.4 ATMOSPHERIC EMISSIONS, TRANSFORMATION AND DEPOSITION
There is little evidence for significant emissions of beryllium to the
atmosphere during ore production. Uncontrolled emissions during ore process-
ing could be locally significant without existing regulations. The 20 percent
of the beryllium lost as waste represents a potential environmental problem.
Emission of beryllium from non-metallurgical sources amounts to 99 per-
cent of U.S. emissions (Table 3-4). The average concentration of beryllium in
coal is between 1.8 and 2.2 ug/g. In 1981, the United States burned 640 x 106
metric tons of coal. Had emission control measures for other pollutants not
been used, 1,300 tons of beryllium would have been emitted, or about 10 times
the annual U.S. production of contained beryllium metal. But emission control
measures are used and there is evidence that 70 to 90 percent of this beryllium
is retained by the captured fly ash. The actual efficiency of beryllium
retention is a subject of controversy and a source of confusion in several
published reports. Phillips (1973) presented data which suggested 86 percent
3-7
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TABLE 3-4. NATURAL AND ANTHROPOGENIC EMISSIONS OF BERYLLIUM*
Natural
windblown dust
volcanic particles
Total
Anthropogenic
coal combustion
fuel oil
beryllium ore processing
Total
*Units are in metric tons
Total U.S.
Production
(106 t/yr)
8.2
0.41
640
148
O.OOS1"
Emission
Factor
(g/t)
0.6
0.6
0.28
0.048
37. 51"
Emission
(t/yr)
5
0.2
5.2
180
7.1
0.3
187.4
Since the production of beryllium ore is expressed in equivalent tons of
beryl, the emission factor of 37.5 is hypothetical.
of the beryllium in coal is released to the atmosphere. Gladney and Owens
(1976) concluded that only 4 percent escapes. Henry (1979), in a report to
the U.S. Environmental Protection Agency, suggested that less than 1 percent
escapes, but that 35 percent remains unaccounted for in mass balance estimates.
A closer look at these three calculations may reveal a part of this discrepancy
All three authors use a mass balance calculation, where the concentration
of beryllium in the coal and the fly ash is known. Since beryllium output is
assumed to be confined to captured fly ash and emitted stack gases, that
fraction of the coal input not found in the fly ash is considered as emitted
to the atmosphere. Neither Phillips (1973) nor Gladney and Owens (1976) knew
the actual mass of the ash produced. In both cases, they reported ash content
published elsewhere in the literature. Phillips measured a beryllium content
of the coal and ash of 2.5 and 5.0 pg/g, respectively, and assumed an ash
content of 7 percent to calculate the fraction not collected as
2.5 ug/g - (0.07) (5 pg/g) _ n ft,
2.5 pg/g~ U'8b
3-8
-------
Gladney and Owens (1976) assumed an ash content of 12 percent and measured
a coal and ash beryllium content of 1.89 and 15.3, respectively. The calcu-
lated percent loss would be
1.89 |jg/g - (Q.12)(15.3 ug/g) = o HOPS
1.89 ug/g
Analytical errors aside, both calculations are extremely sensitive to the
assumed ash content of coal, which varies between 7 and 14 percent. Using
this range, the data of Phillips show beryllium losses of 72 to 86 percent anc
the data of Gladney and Owens, 0 to 43 percent. It is also possible that
errors of analysis were made. Coal and ash from the same plant that Phillips
investigated were reported by the Southwest Energy Study (1972) to be 0.43 and
7 |.ig Be/g, respectively. In the range of 7 to 14 percent ash, these data
would yield a percent beryllium loss of less than zero, however. If the
average beryllium content of western coal (1 ug/g) is used with the Phillips
data, the loss to the atmosphere ranges from 30 to 65 percent.
Henry (1979) made similar measurements of coal and ash. Sixty-five
percent of the beryllium was accounted for in the ash. However, measurements
of beryllium at the precipitation outlet and in the stack did not account for
the remainder of the beryllium. In simulation runs, Yeh et al. (1976) found
77 percent retention of the beryllium in the slag and fly ash.
It seems reasonable to conclude that between 10 and 30 percent of the
beryllium in coal is emitted to the atmosphere from coal during the combustion
process. While not all coal burning facilities control emissions to the
extent of power plants, the following calculation is a conservative estimate
of total beryllium emissions from coal in the United States during 1981.
640 x 106 t coal/yr x 1.4 g Be/t coal x (0.1 to 0.3) - 180 + 90 t Be/yr
efficiency
Emission from oil-burning facilities may be calculated from the average
beryllium concentrations of fuel oil (Anderson, 1973), an assumed loss of 40
Q
percent, and a consumption of 1.1 x 10 tons residual oil per year. From this
calculation, it appears that 7.2 tons beryllium are emitted from this source.
Although no data exist, it is likely that no more than 0.5 percent of the
contained beryllium is emitted during the metallurgical process, or about 0.12
3-9
-------
tons/year. Therefore, 185 tons/year would seem to be a reasonable estimate for
anthropogenic beryllium emissions from the United States. Assuming a residence
I line ul 1(1 il.iy., .1:1 i>llc
-------
been measured in the United States, the preceding calculations based on metals
of similar particle size are an acceptable substitution.
There are no reports of beryllium concentrations in precipitation. If
half the emissions return to the surface of the earth as wet precipitation,
the average concentration of beryllium in rain or snow would be 0.01 ng/g,
which is far below the detection limit of most analytical techniques. Meehan
and Smyth (1967) reported an average of 0.07 ng/g in rain in Australia.
Beryllium oxide is very insoluble and would not be mobilized in soil or
surface water, at environmental pH ranges of 4 to 8. If this is indeed the
chemical form of beryllium at the time of deposition, beryllium would not move
easily along grazing food chains, but would be confined to soils and sediments.
If, however, significant amounts of beryllium are converted to chloride,
sulfate, or nitrate during atmospheric transport, solubility upon deposition
would be greatly enhanced and mobility within ecosystems could be facilitated.
Biochemically, beryllium is classified as a fast-exchange metal, a property
that potentially allows beryllium to interfere with the transport of nutritive
metals such as calcium into eucaryotic cells (Wood and Wang, 1983). There is
a need for further research on the effects of pH on the mobility of beryllium
in ecosystems and the subsequent effects on plants and animals. While further
discussions of the effects of beryllium on natural populations of plants and
animals are beyond the scope of this document, it is worth noting that some
toxic effects have been reported. These are reviewed by Brown (1979).
3.5 ENVIRONMENTAL CONCENTRATIONS OF BERYLLIUM
3.5.1 Ambient Air
Beryllium is measured at many of the stations in the SLAMS (State and
Local Air Monitoring Stations) and NAMS (National Air Monitoring Stations)
networks. The data are available from the SAROAD data base of the U.S. En-
vironmental Protection Agency. The detection limit for these analyses is 0.03
ng/m and most annual averages are at this concentration. Annual averages
which exceeded 0.1 ng/m3 during 1977-81 are listed in Table 3-5. The highest
24-hour observation was 1.78 ng/m3 reported in Atlanta, Georgia during 1977.
There were no locations where the 30-day average concentration approached the
10 ng/m3 standard set by the U.S. Environmental Protection Agency, (FR, 1973).
3-11
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TABLE 3-5. CONCENTRATIONS OF BERYLLIUM IN URBAN ATMOSPHERES
3
Values exceeding 0.1 ng/m are reported for the period 1977-81. Some values
for 1981 are not yet available. Units are in ng/m3. Values in parentheses
are the number of 24-hour observations used to determine this average annual
air concentration.
Birmingham, AL
Douglas, AZ
Tucson, AZ
Ontario, CA
Hialeah, FL
Miami, FL
St. Petersburg, FL
Tampa, FL
Atlanta, GA
East Chicago, IN
Gary, IN
Hammond, IN
Indianapolis, IN
Des Moines, IA
Kansas City, KS
Ashland, KY
Baton Rouge, LA
Portland, ME
Baltimore, MO
Fall River, MA
New Bedford, MA
Flint, MI
Lansing, MI
Kansas City, MO
Omaha, NB
Camden Co. , NJ
Perth Amboy, NJ
Trenton, NJ
Albuquerque, NM
Niagara Falls, NY
Syracuse, NY
Cincinnati , OH
Cleveland, OH
Columbus, OH
Dayton, OH
Mansfield, OH
Portsmouth, OH
Steubenville, OH
Toledo, OH
Youngstown, OH
1977
.11(20)
.12(13)
.11(23)
.19(27)
.16(23)
.19(26)
.22(24)
1978
.11(20)
.11(22)
.13(24)
.11(18)
.15(25)
.14(28)
.37(19)
.11(29)
.12(26)
.12(29)
.13(15)
.13(28)
-17(5)
.19(2)
.11(30)
.15(26)
.11(26)
.21(26)
.15(29)
.14(27)
.13(24)
.19(27)
1979 1980
.25(7)
.14(11)
.16(21)
.12(23)
.11(19)
.18(5)
.11(6)
.13(10)
-17(14)
.11(19)
.11(16)
.17(28)
.11(11)
.14(26) .18(10)
1981
.11(7)
.22(1)
.11(7)
-11(6)
.13(4)
.22(6)
(continued on the following page)
"U/A
3-12
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TABLE 3-5. (continued)
1977
1978
1979
1980
1981
Guayanilla Co.
Baja Co., PR
Knoxville, TN
Nashville, TN
Dallas, TX
El Paso, TX
Houston, TX
PR
.11(15)
11(29)
,14(25)
17(17)
.15(7)
.17(5) .16(5)
.13(11)
.40(2)
Lubbock, TX
Pasadena, TX
Seattle, WA
Charleston, WV
Milwaukee, WI
.13(23)
.15(23)
.13(25)
.17(13)
.11(7)
3.5.2 Soils and Natural Waters
Shacklette et al. (1971) reported a geometric mean of 0.6 ug Be/g in soil
for 847 samples distributed evenly across the United States. Only 12 percent
of the samples exceeded 1.5 ug/g. The soils were sampled at a depth of 20 cm
to avoid surface contamination. These results are lower than those of previous
geochemical surveys by Vinogradov (1959), Hawkes and Webb (1962), and Mitchell
(1964), all of whom reported means of 6 |jg/g. The differences can most reason-
ably be explained by limitations in analytical techniques. Nevertheless, the
0.6 |jg/g average is somewhat consistent with the average crustal value of 2.8
reported by Mason (1966).
Global values for beryllium in natural surface waters range from 0.01 to
1.0 ng/g (Bowen, 1979). The lowest value (0.01 ng/g) was reported by Meehan
and Smythe (1967) in Australia. These concentrations are in the same range as
the calculated concentration of beryllium in precipitation (0.01 ng/g) discussed
above. Seawater was reported to be 0.0005 ng/g by Merrill et al. (1960) and
0.0056 ng/g by Bowen (1979). There are no available reports of beryllium in
groundwater.
3.6 PATHWAYS TO HUMAN CONSUMPTION
The possible sources of human consumption of beryllium are inhaled air,
food, drinking water, and ingested dusts. The environmental sources of beryl-
lium which can lead to human consumption are shown in Figure 3-1. In this
3-13
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INDUSTRIAL
EMISSIONS
CRUSTAL
WEATHERING
SURFACE AND
GROUND WATER
DRINKING
WATER
Figure 3-1. Pathways of environmental beryllium concentrations leading to potential human exposure.
3-14
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section, beryllium concentrations in the four compartments immediately pre-
ceding human consumption are estimated for a typical background human environ-
ment not exposed to extraordinary sources of beryllium. These values are
combined with known consumption rates for air, food, water and dust to estimate
the typical daily consumption of beryllium. The value of this determination
lies not in its precision, but in its ability to eliminate misguided estimates
of human consumption which are exceptionally high or low.
Because of the sporadic location of stations reporting atmospheric con-
centrations of beryllium, the average of reports may be biased toward the high
region. A probable average concentration for air concentration would be 0.08
3
ng/m for residential environments not located near an unusually high source
of beryllium. The 0.08 ng/m value as measured at a monitoring station could
be influenced by vertical and horizontal distance from the source and by an
indoor vs. outdoor environment of filtered or unfiltered air.
Limited data for foods are available. Meehan and Smythe (1967) analyzed
a few foods from Australia, reporting values from 0.05 to 0.15 ng/g fresh
weight. Beryllium in drinking water appears to range from 0.01 to 1.2 ng/g,
with an average of 0.2 ng/g. There are no reports of beryllium in household
dust, but if it is assumed that this dust is derived solely from the atmos-
3
phere, an air/dust ratio of 600 would be a reasonable estimate. At 0.1 ng/m ,
household dust would contain 60 ng/g.
3
The average American adult inhales 20 m of air/day, and consumes 1200 g
of food and 1500 g of water and beverages (Pennington, 1983). The daily
consumption of dust is not well established, but a conservative estimate of
0.02 g is made here for the purpose of illustration. The data in Table 3-6
show that the typical American adult consumes 423 ng/day of beryllium, most of
which comes from food and beverages. This calculation shows that direct air
inhalation or the consumption of dust derived from air have little impact on
the total consumption of beryllium. This overall determination is extremely
sensitive to the average concentration of beryllium in food and water (99.3
percent of total daily consumption). It is likely that there is some variation
in these numbers according to the types of food and beverages eaten, and that
there is some atmospheric contribution to the beryllium concentrations of food
and beverages.
Daily consumption from extraordinary sources, such as occupational expo-
sures or secondary occupational exposure to workers' families, would cause
3
increases in the air and dust categories. At 2 pg/m air concentrations (the
3-15
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TABLE 3-6. POTENTIAL HUMAN CONSUMPTION OF BERYLLIUM FROM
NORMAL SOURCES IN A TYPICAL RESIDENTIAL ENVIRONMENT
Air
Food
Water
Dust
Environmental
Concentration
0.08 ng/m3
0.1 ng/g
0.2 ng/g
60 ng/g
Total Daily
Human
Intake
20m3
1200g
1500g
0.02g
Total
Consumption
1.6 ng/day
120
300
1.2
422.8
Percent of
Total Daily
Consumption
0.4%
28.4%
70.9%
0.3%
current occupational standard), a worker's exposure for an 8-hour shift would
increase to more than 13,000 ng/day. Dust of beryllium metal or metal oxide,
at a daily consumption of 0.02 g (including dust consumed during the working
shift and that carried home on the clothing of the worker), could add 2,000,000
ng beryllium to the total daily consumption. There is also the possibility
that certain individuals might be exposed to beryllium from implanted dental
prostheses. Although the leaching of nickel and chromium from alloys used in
prostheses has been reported, no studies of beryllium are available.
3-16
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4. BERYLLIUM METABOLISM IN MAN AND ANIMALS
4.1 ROUTES OF BERYLLIUM ABSORPTION
4.1.1 Beryllium Absorption by Inhalation
There are no data on deposition or absorption of inhaled beryllium in
human beings. However, it can be expected that beryllium particles will
follow the same general laws as other inhaled particles in that dose, size and
solubility will be important factors for deposition and clearance.
Beryllium has been found in lungs of persons without known occupational
exposure to the metal. Cholak (1959) analyzed 70 lungs from unexposed indivi-
duals and reported an average concentration of 3.3 ug Be/kg dry weight (range:
0.1-19.8 ug/kg). Meehan and Smythe (1967) reported a mean level of 1.3 ug/kg
wet weight (range: 0.3-2.0 ug/kg) in 4 human lungs corresponding to about
6 ug/kg dry weight. Sumino et al. (1975) analyzed beryllium in the lungs of a
few Japanese subjects and found concentrations of up to 30 ug/kg wet weight.
In viewing these above findings, it should be kept in mind that smoking habits
were not taken into account. In addition, it is difficult to validate such
data, as well as other data on beryllium in tissues or body fluids, since
there have not been any interlaboratory or quality control studies. There are
no reference samples for beryllium in tissues or body fluids. The data by
Cholak have been used as a basis for determining an upper normal level of
beryllium in lung of 20 pg/kg dry weight.
Animal studies have shown that rats exposed to beryllium sulfate (average
3
beryllium concentration of 35 ug/m ) for 7 hr/day, 5 day/week, for 72 weeks,
reached a plateau in lung beryllium concentrations after 36 weeks of exposure.
A plateau in the tracheobronchial lymph nodes was also reached at that time.
After cessation of exposure, pulmonary beryllium was first eliminated with an
initial half-time of two weeks, followed by much slower elimination (Reeves
et al., 1967; Reeves and Vorwald, 1967).
In studies which have examined the distribution of radioactive beryllium
compounds via intratracheal injection, Kuznetsov et al. (1974) reported a
half-time of 20 days in rats given a single injection of beryllium chloride,
whereas Van Cleave and Kaylor (1955) reported that the citrate was rapidly
eliminated in rats. Longer observation periods in rats, however, have indi-
cated a half-time of about 325 days after inhalation exposure to beryllium
4-1
-------
oxide (Sanders et al., 1975, 1978). About 25 percent of beryllium cleared
from the lungs was translocated to regional lymph nodes (Sanders et al.,
1978).
It is not known in detail how retained beryllium is stored in the lungs.
It is likely that soluble beryllium compounds will be transformed to insoluble
complexes with, for instance, phosphate, when the beryllium concentration is
above a certain level (Reeves and Vorwald, 1967). Beryllium particles in the
insoluble state will likely be taken up by the macrophages as demonstrated j_n
vitro (Hart and Pittman, 1980). At high jjn vitro and jji vivo exposures,
beryllium has been shown to be very toxic to alveolar macrophages (Camner
et al., 1974; Sanders et al., 1975).
Zorn et al. (1977) subjected rats and guinea pigs to a nasal exposure of
beryllium sulfate aerosol, with Be added as the chloride, for a period of
three hours. The average deposition of Be was reported to be 5.6 ng, which
suggests that the total uptake of beryllium might have been 1624 |jg. Clearance
from the lungs must have been rapid since 13.5, 60, and 10 percent of the
retained dose was in the skeleton, lungs, and excreta, respectively, by the end
of the three-hour exposure period. Animals were killed at 20, 48, 64, 72, 96,
144, and 408 hours after exposure. During the first 5 days, there was a rapid
clearance from the lungs, and after a week only 2 percent of the dose remained
in the lungs. At approximately 17 weeks, the retained dose decreased to about
1.5 percent. Unfortunately, the authors did not provide information on the
number of animals in each test group or on the number of animals killed at
each of the designated time intervals.
4.1.2 Gastrointestinal Absorption of Beryllium
There are no data on the absorption of beryllium compounds in human
beings. Estimates from animal experiments generally show low values, <1
percent in pigs (Hyslop et al., 1943), rats (Crowley, 1949; Furchner et al.,
1973), mice, monkeys, and dogs (Crowley, 1949; Furchner et al., 1973). The
latter studies were done using tracer amounts of Be. Reeves (1965) gave two
groups of rats, four in each group, beryllium sulfate in drinking water, the
average daily intake being about 6.6 and 66.6 ug Be, respectively. In each
group, one rat was killed after 6, 12, 18, and 24 weeks of exposure. Reeves
found that 60-90 percent of the ingested beryllium was eliminated via feces,
indicating a relatively high absorption. However, the total amount of beryllium
4-2
-------
in the skeletons from the four rats exposed to 6.6 ug/day was the same as in
the skeletons from the four rats exposed to 66 ug/day, being on the average
1.49 and 1.19 ng, respectively. This suggests either that the relative absorp-
tion was much less in the high exposure group or that the uptake in bone was
independent of absorbed dose. If it is assumed that 50 percent of absorbed
beryllium goes to the skeleton and that the biological half time in the skeleton
is 1000 days, the daily absorbed amount would be around 40 ng, i.e. about
0.6 percent of the oral daily dose.
In his reporting of the study, Reeves (1965) discussed the possibility
that at the high exposure level, beryllium might be precipitated as the
hydroxide as well as the phosphate. However, he goes on to reject this possi-
bility based on the finding that the absorption rate calculated from fecal
elimination data was similar in the two groups of rats. This rejection ignores
the fact that the skeleton data do support the theory that the absorption rate
of beryllium might be dose-dependent.
Morgareidge et al. (1977) claimed that uptake in bone was dose-dependent
when rats were orally exposed to beryllium at concentrations of 5, 50, and
500 mg/kg feed for up to two years. Unfortunately, no quantitative data are
given in the abstract discussing this study.
4.1.3 Percutaneous Absorption of Beryllium
There are no data on skin absorption in human beings. Tracer studies
showed that small amounts may be absorbed from the rat tail (Petzow and Zorn,
1974). Belman (1969) reported that ionic beryllium applied to the skin will
bind to epidermal constituents, mainly alkaline phosphatase. However, the
chemical properties of beryllium make it unlikely that any significant absorp-
tion can occur through intact skin.
4.1.4 Transplacental Transfer of Beryllium
In a study by Bencko et al. (1977), the soluble salt of beryllium, BeCl2,
was evaluated for its ability to penetrate the placenta and reach the fetus of
ICR SPF mice. Radiolabelled 7BeCl2, injected into the caudal vein of 7 to 9
mice, did cross the placenta and was deposited in various organs of the fetus
(see Chapter 5 for detailed discussion of this study).
No other data are available on placental transfer of beryllium.
4-3
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4.2 TRANSPORT AND DEPOSITION OF BERYLLIUM IN MAN AND EXPERIMENTAL ANIMALS
Beryllium absorbed from the gastrointestinal tract will distribute mainly
to the skeleton (Reeves, 1965; Mullen et al., 1972). Some beryllium has been
found in the liver, but other organ concentrations have been reported to be
very low (Reeves, 1965).
After injection of radioactive beryllium compounds, the highest concentra-
tions have been found in bone and liver of rats (Hard et al., 1977) and cows
(Mullen et al., 1972). The physicochemical state of the injected compound
determines the main site of deposition; soluble beryllium rapidly distributes
to the skeleton, whereas colloidal forms of beryllium mainly go to the liver
(Klemperer et al., 1952). In rat blood, large doses of injected beryllium
tend to aggregate and bind to phosphate, whereas small doses result in rela-
tively more beryllium being in a diffusible form (Vacher and Stoner, 1968a,b).
At low doses of beryllium, the main binding in human blood has been reported
to be the prealbumin and crglobulin fractions of plasma (Stiefel et al. ,
1980). Recent data indicate that there is a binding site for beryllium in
the lymphocyte membrane (Skilleter and Price, 1984).
Witschi and Aldridge (1967) studied the dose-dependence of this effect in
rats. They found that less than 10 percent of the intravenous doses of beryl-
lium sulfate (0.75-15 ug Be/kg b.w.) was in the liver after 24 hours, whereas
more than 25 percent was found in the liver following the administration of
doses of 63 ug/kg b.w. or higher. They also found that with increasing dose
more beryllium was found in the nuclear fraction and relatively less in the
supernatant when the subcellular fractions of the rat livers were examined.
At the lowest exposure (0.75 ug), the light mitochondrial fraction had the
highest amount of beryllium and some evidence was presented for beryllium
being located in the lysosomes. Further evidence for a role of lysosomes in
hepatic accumulation of beryllium has been presented by Skilleter and Price
(1979).
There are few data on beryllium levels in human beings. Analysis of
tissues from people occupationally exposed to beryllium showed that, generally,
the concentrations were highest in bone, liver, and kidney (Tepper et al.,
1961). Meehan and Smythe (1967) reported that in the brain, kidney, spleen,
liver, muscle, and heart, the concentrations were generally less than 1 ug/kg
wet weight. However, in one bone sample, the concentration was 2 ug/kg, and
in five vertebrae, the mean was 3.6 ug/kg. The form in which beryllium is
4-4
-------
stored in bone is presently unknown. At low exposure to beryllium, it may be
bound to prealbumin and crglobulin fractions in plasma (Stiefel et al., 1980).
4.3 EXCRETION OF BERYLLIUM IN MAN AND ANIMALS
In rats given intravenous injections of tracer doses of Be, 15 and 64
percent of the doses were excreted, via urine, 1 and 64 days after dosing,
respectively (Crowley et al., 1949). In mice, monkeys and dogs, urinary
excretion was the main elimination route the first days after parenteral
dosing; however, later, excretion via the gastrointestinal tract equaled that
of urinary excretion (Furchner et al., 1973). In early studies, Scott et al.
(1950) discovered that increasing the dose in experimental animals resulted in
lowering urinary excretion rates. Biliary excretion seems to play a minor
role in total beryllium excretion (Cikrt and Bencko, 1975).
The biological half-time of beryllium administered via intravenous and
intraperitoneal injections has been found to consist of three components, the
long-term component being 1270, 1210, 890, and 770 days in dogs, mice, rats,
and monkeys, respectively (Furchner et al., 1973).
After oral dosing, Reeves (1965) found that less than 1 percent of the
administered dose was excreted in urine of rats.
Quantitative data on excretion of beryllium in humans are scarce. Very
small amounts of beryllium (<0.1 ug/1), measured by emission spectroscopy,
were found in urine from non-exposed persons (Lieben et al., 1966). Much
higher values (averages of 0.9 p.g/1) were reported in 120 people from Califor-
nia (Grewal and Kearns, 1977) and 20 individuals from Germany (Stiefel et al.,
1980). In both the above studies, flameless atomic absorption spectroscopy
was used to measure the beryllium concentrations. The differences observed
between these two studies and that of Lieben et al. may have been due to
differences in the accuracies of the analytical methods used.
Since human dietary intake of beryllium is low and animal studies suggest
that gastrointestinal absorption would be low, total human body burden is
likely quite low and, therefore, only a few nanograms of beryllium would be
expected to be excreted daily. Based on the limited data reported by Meehan
and Smythe, the soft tissue burden of an adult will likely be less than 20 pg
and the skeletal burden will be about 30 (jg.
Presently, no estimates exist of the biological half-time of beryllium in
humans. Limited evidence suggests that the half-time in bone is likely to be
many years.
4-5
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5. BERYLLIUM TOXICOLOGY
The following chapter discusses the non-mutagenic/carcinogem'c effects of
exposure to beryllium. Because of the greater volume of information available
regarding the mutagenic and carcinogenic effects of beryllium, these topics
have been discussed in the following chapters.
5.1 ACUTE EFFECTS OF BERYLLIUM EXPOSURE IN MAN AND ANIMALS
5.1.1 Human Studies
Acute lung disease from excessive exposure to beryllium compounds was
first reported in the 1930's in Europe. The first U.S. case was reported in
1943 (Van Ordstrand et al., 1943). In the 1940's, many hundreds of cases
occurred, but today, with improved working conditions, acute beryllium poison-
ing is uncommon.
Acute lung disease has been caused by inhalation of soluble beryllium
compounds, e.g., the fluoride with acidic pH or the oxide, and the symptoms
have been nonspecific with chemical pneumonitis as the most severe manifesta-
tion (Freiman and Hardy, 1970; Reeves, 1979). In a study of six fatal case
reports, Freiman and Hardy (1970) reported that death occurred between 17 days
and 10 weeks after exposure. Interstitial edema and cellular infiltration
dominated the histological tissue analyses. The beryllium concentrations in
the lung ranged from 4 to 1800 ug/kg.
In most cases of acute poisoning, recovery is slow, taking several weeks
or months (Reeves, 1979). In the U.S. Beryllium Case Registry (BCR), a file
on reported cases of acute and chronic beryllium disease, 215 cases of acute
poisoning were registered up to 1967 (Freiman and Hardy, 1970). Since that
time, an additional 9 cases, as of 1983, have been reported (Eisenbud and
Lisson, 1983).
That there still is an occupational risk for acute beryllium disease is
shown by a recent case report by Hooper (1981). An 18-year-old man involved
in sandblasting and exposed to grinding dyes containing a copper-beryllium
alloy developed acute respiratory disease. Open lung biopsy, six days after
exposure, showed interstitial pneumonitis and slightly elevated beryllium
concentrations in the lung tissue (28 ug/kg dry weight compared to normal
levels of <20 ug/kg).
5-1
-------
Acute skin effects in the form of contact dermatitis after contact with
soluble beryllium salts have been described (Van Ordstrand et al. , 1945).
5.1.2 Animal Studies
Acute chemical pneumonitis has been produced in a great variety of animals
exposed to beryllium sulfate or fluoride (Stokinger et al., 1950). Some
insoluble compounds, especially low-fired beryllium oxide, have also caused
acute effects in rats (Hall et al., 1950). The concentrations needed to cause
acute effects have generally been on the order of several mg/m .
Injection of beryllium compounds can cause acute liver damage (Cheng,
1965; Aldridge et al., 1950).
5.2 CHRONIC EFFECTS OF BERYLLIUM EXPOSURE IN MAN AND ANIMALS
5.2.1 Respiratory and Systemic Effects of Beryllium
5.2.1.1 Human Studies—The fact that beryllium can cause chronic lung disease
was first reported by Hardy and Tabershaw in 1946. They presented data on 17
persons employed in the fluorescent lamp manufacturing industry. The main
symptoms noted were dyspnea on exertion, cough, and weight loss. In most
cases the symptoms first appeared several months or even years after the last
exposure. The patients were generally young, below 30 years of age, and the
majority were women. X-ray examinations and autopsy findings provided addi-
tional information. The X-rays showed that an early sign of chronic beryllium
poisoning was a fine diffuse granularity in the lungs. In the second stage, a
diffuse reticular pattern was also seen, and in the third stage, distinct
nodules could be seen. Histological examination of the lungs in an autopsy
case showed a granulomatous inflammation characterized by central and eccentri-
cally located giant cells of the foreign body type in the alveoli. Infiltration
of plasma cells and lymphocytes was another feature. After generally less
than two years of illness, five deaths occurred among the 17 persons. In a
couple of cases, some recovery was noted and in some other cases persistent
disability occurred.
This pioneer study of chronic beryllium disease led to further studies
which have been documented in papers by Hardy (1980) and Eisenbud (1982). In
addition to further cases of occupational beryllium poisoning, there have also
been reports on "neighborhood cases," i.e., beryllium disease in persons living
in the vicinity of beryllium-emitting plants. In these cases, exposure has
5-2
-------
not only been to beryllium in ambient air, but also to contaminated clothing
brought into the house from occupationally exposed members of the household
(Eisenbud et al., 1949). At least 3 children, ages 7-14 years, have been
among these cases (Hall et al., 1959).
These findings and the experience from acute beryllium poisoning led to
the initiating of beryllium standards in both the industrial and general
environment. To prevent acute disease, a TLV of 25 jjg/m was proposed in 1949
as a maximum permissible peak occupational exposure during 30 minutes, and a
level of 2 pg/m was set as an average 8-hour exposure. For the general
3
environment, a level of 0.01 jjg/m was proposed. It should be noted that the
3
2 |jg/m standard was, in fact, not based on actual dose-response relationships.
As stated by Eisenbud (1982), this was a standard based on the molar toxicity
of beryllium in relation to some heavy metals like lead and mercury, with TLVs
around 100 pg/m .
While these proposed standards seemed to prevent acute poisoning, during
the following years, many new cases of chronic beryllium disease were dis-
covered, mainly as a result of heavy exposures in the years 1940 to 1946.
This led to the foundation of the previously mentioned Beryllium Case Registry
in 1952. The intention of the Registry was that it would serve as a file for
all cases of acute and chronic beryllium disease, from which information on
the development and clinical manifestations of beryllium disease could be
obtained. Since 1978, the Registry has been maintained by the National Insti-
tute for Occupational Safety and Health.
Throughout the years, many scientific reports have appeared based on the
information in the Registry. In 1959, Hall et al. presented some data on 601
persons who at that time (1959) had entered the registry. As seen in Table 5-1,
the majority of male cases in 1959 were acute, but in later reports the number
of chronic disease cases increased and now number more than 600 in total,
whereas only a few more cases of acute disease have been reported. It should
be noted that 28 of the acute cases in Table 5-1 were also classified as
chronic. In 1966-1974, 74 new cases were reported to the BCR, of which 36 had
been exposed after 1949 (Hasan and Kazemi, 1974).
Typical of chronic beryllium disease is that it may appear many years after
cessation of exposure. In Table 5-2, it can be seen that the time since last
exposure in more than 20 percent of the cases reported up to 1959 was more than
5 years, the maximum being 15 years. There has been some overlapping between
5-3
-------
TABLE 5-1. BERYLLIUM REGISTRY CASES, 1959
Acute
Chronic
Men
227
191
Women
20
191
Total
247 (39%)
382 (61%)
Dead
15 ( 6%)
121 (31%)
Source: Hall et al. (1959)
TABLE 5-2. TIME FROM LAST EXPOSURE TO FIRST SYMPTOM* IN THE BCR, 1959
Time
Less than 1 month
1 month to 1 year
1-5 years
5-10 years
More than 10 years
Cases of beryllium disease
126
27
89
56
12
310
%
41
9
29
18
4
^Maximum was 15 years.
Source: Hall et al. (1959)
acute and chronic disease, but generally the disease has been registered as
chronic if it has lasted more than one year.
In the latest report, 897 cases have been registered in the BCR, 10 of
which have been added since 1978 (MMWR, 1983). Eisenbud and Lisson (1983)
reported on 888 cases, but mentioned that they knew about 45 chronic cases
which had not been included as of their report. Therefore, the total number
of cases may well be over 900.
Of the 888 cases reported by Eisenbud and Lisson, 224 were classified as
acute. This number is smaller than the one given in Table 5-1, but as mentioned
earlier, 28 acute cases in that table were also classified as chronic. The
chronic cases were reported to be 622, leaving 42 cases unaccounted. Of the
622 cases, 557 occurred in individuals occupationally exposed and 65 occurred
among members of the general populace. Of the latter, 42 were attributed to
ambient air exposure and 23 to dust exposure in the homes.
5-4
-------
The majority of the occupational cases were either from exposures within
the fluorescent lamp industry (319) or within beryllium extraction plants
(101). In 62 percent of the occupational cases, dates for first exposure and
onset of disease were available. Figure 5-1 shows that latency times may have
been up to 40 years, but have been declining in recent years. Eisenbud and
Lisson acknowledged that caution should be exercised in interpreting the data
in Figure 5-1, as a rough correspondence between the maximum latency time and
number of years elapsed since first exposure must exist. Thus, it could be
argued that cases with longer latencies will develop among more recent cohorts
in later years. While the authors disputed this argument by noting that reduc-
tion in maximum latency paralleled the reduction in mean latency, which also de-
clined through time (Table 5-3); nevertheless, it is clear that a person exposed
in 1960 cannot, by the end of the study period, have a latency time of more than
20 years.
Some of the most common symptoms of chronic beryllium disease are shown
in Table 5-4 (Hall et al., 1959). These symptoms confirm what was earlier
reported by Hardy and Tabershaw in 1946. Table 5-5 shows some of the signs of
chronic beryllium disease. The cardiovascular signs can be attributed to the
cor pulmonale, which is a sequela to the severe forms of chronic beryllium
disease. There are also some other signs which may be seen as pure systemic
effects of beryllium exposure.
An extensive description of chronic beryllium disease was presented by
Stoeckle et al. (1969). In that paper, mainly clinical and X-ray findings and
results of treatment were presented. In another paper by Freiman and Hardy
(1970), the pulmonary pathology was presented. In the paper by Stoeckle et
al., data were shown on 60 patients with chronic beryllium disease, who had
been investigated at the Massachusetts General Hospital between 1944 and 1966.
This group came from different industries and no data were presented on expo-
sure levels, so the data cannot be used for any dose-response estimations.
However, valuable information was given on the clinical findings and the
diagnostic problems encountered in the examination of these patients. In
addition to the pulmonary effects, there was further evidence for extrapul-
monary signs of beryllium disease. In some patients, granulomas were found in
muscle or skin.
Some of the features of chronic beryllium disease are similar to those
seen in sarcoidosis. In the paper by Stoeckle et al., as well as in an earlier
paper by Israel and Sones (1959), the differentiation of these two diseases is
5-5
-------
on
o-i
50
40
I 30
O
2
H 20
10
32
•
•t
• o
0
o
• V.
o
§
0
O O
;j«*I°8Jjo8i°*
°f!l°*9li*!:0
!8 o
I
I
• EXPOSED TO BERYLLIUM PHOSPHORUS
o EXPOSED TO OTHER BERYLLIUM
COMPOUNDS
8
o
o o
o
8
I
00
I
o o
o
o o
o ^
40
72
48 56 64
YEAR OF FIRST EXPOSURE
Figure 5-1. Latency according to year of first exposure (occupational berylliosis).
Source: Eisenbud and LJsson (1983).
80
-------
TABLE 5-3. CHANGES OF LATENCY FROM 1922 TO PRESENT IN
OCCUPATIONAL BERYLLIOSIS CASES
Period of First
Exposure
1922-1981
1922-1937
1938-1949
1950-1959
1960-1981
No. of Cases
347*
33
264
32
18
Latency, ^yr
Mean Range
11 1-41
16 4-40
9.8 1-39
9.6 1-25
6.6 1-13
*Cases were included only if both dates of first exposure and diagnosis of
first symptoms were known; 62 percent of all chronic cases reported to the
Registry were included.
Source: Eisenbud and Lisson (1983).
TABLE 5-4. SYMPTOMS OF CHRONIC BERYLLIUM DISEASE
Symptom
Dyspnea
on exertion 69
at rest 17
Weight loss
more than 10% 46
0% to 10% 15
Cough
nonproductive 45
productive 33
Fatigue 34
Chest pain 31
Anorexia 26
Weakness 17
Source: Hall et al. (1959)
5-7
-------
TABLE 5-5. SIGNS OF CHRONIC BERYLLIUM DISEASE*
Sign %
Chest signs 43
Cyanosis 42
Clubbing 31
Hepatomegaly 5
Splenomegaly 3
Complications
Cardiac failure 17
Renal stone 10
Pneumothorax 12
*Signs are not included when they are attributable to cardiac failure.
Source: Hall et al. (1959)
discussed. The main difference is that in sarcoidosis there is much more
systemic involvement, as noted in more than 80 percent of the cases. X-ray of
the lungs may, however, show very similar pictures.
Among laboratory findings in cases of beryllium disease, hypercalcemia,
hypercalcuria, stone formation, and osteosclerosis have been noticed (Stoeckle
et al., 1969) as has hyperuricemia (Kelley et al., 1969).
In addition to the studies based on the BCR, there have also been some
studies within industrial populations. Wagoner et al. (1980) conducted a
mortality study on a cohort of 3055 workers exposed to beryllium in a plant in
Pennsylvania. (See Section 7.2 for detailed discussion of lung cancer within
the cohort.) Among causes of death other than lung cancer, there was a signi-
ficant excess of heart disease (396 observed versus 349 expected) and respira-
tory disease other than influenza and pneumonia (31 observed versus 18.7
expected). It is conceivable that some of the cardiac deaths were, in fact,
caused by cor pulmonale secondary to beryllium disease. There are no data
that indicate that beryllium exposure via inhalation has a direct effect on
the cardiovascular system.
These data can be compared to a mortality study by Infante et al. (1980)
on 421 white males listed in the BCR during the period of 1952 through 1975.
5-8
-------
Heart disease was stated to be the cause of death in 31 of these cases (29.9
were expected), whereas respiratory disease other than influenza and pneumonia
was the cause of death in 52 cases (only 1.6 were expected).
Recently, it has been suggested that beryllium exposure may cause granu-
lomas in different parts of the body which may prove fatal when the myocardium
is affected. Hozberg and Rajs (1980) reported granulomatous myocarditis as
the cause of death in two individuals occupationally exposed to beryllium.
Results of studies on respiratory function have been presented by Andrews
et al. (1969), Kanarek et al. (1973), and Sprince et al. (1978). Andrews et
al. performed lung function tests, e.g., vital capacity and FEV,, on 41 patients
from the BCR with chronic beryllium disease. Only in two patients were the
test results normal; 16 out of the 41 patients had airway obstruction.
The studies by Kanarek et al. and Sprince et al. were performed on workers
employed in beryllium extraction and processing plants. In the first study,
214 employees were examined. They had been exposed for 1 to 14 years and
exposure had started after recommended occupational standards had been set.
It was known, however, that the recommended standards of 2 and 25 ug/m for
8-hour and short-term exposures, respectively, had been exceeded. In some
3
areas of the plants peak exposures were above 1 mg/m . A large number of lung
function tests were performed, including FVC, FEV-,, and gas exchange. Among
31 subjects with X-ray abnormalities of the lung, there were 11 with hypoxemia
at rest, but these subjects were also heavy smokers. In this study, there was
no control group and it is, therefore, difficult to establish to what extent
smoking or beryllium caused some of the effects. However, in two subjects,
lung biopsies were performed, and in one of these cases a diffuse granulomatous
reaction, typical for beryllium exposure, was found. In both cases the beryl-
lium content of the lung was elevated. It is noteworthy that the case with
granulomatous reaction had much lower beryllium concentrations in the lung
tissue than the case without tissue changes.
A follow-up was made 3 years later on these workers, as reported by
Sprince et al. (1978). Exposure levels were now much lower due to new engineer-
ing, and peak concentrations were now less than 25 ug/m . For some operations,
3
peak concentrations were even less than 2 ug/m . One hundred eleven workers
who had participated in 1971 and had not changed smoking category were studied
5-9
-------
(Table 5-6). There were no major differences between the results from the two
examinations, but as seen in Table 5-7, there had been some improvement of
hypoxemia as indicated by the results of the Pan determinations. In the 13
2
persons who had clearly demonstrated hypoxemia in 1971, there was a highly
significant rise--on an average, 19 mm higher--in Pan in 1974. Among the 98
2
workers who had normal Pan in 1971, the average increase was 4.1 mm.
2
Of the 31 subjects who had X-ray abnormalities in 1971, nine now showed
normal X-ray readings. These findings indicate that some minor changes might
be reversible in beryllium-exposed workers, if exposure is reduced. A new
follow-up was conducted in 1977 and briefly reported (Sprince et al., 1979).
The improvement in Pan remained and there was a tendency towards normaliza-
2
tion of lung X-rays. It is obvious, however, that, due to long latency
times, longer follow-ups are necessary before any final conclusions can be
i
made with regard to prognosis.
In addition to the U.S. studies, studies have been conducted in other
countries on workers exposed to beryllium (Cotes et al. , 1983; Bencko et al.,
1980).
In a recent British study, Cotes et al. (1983) presented data on workers
exposed to beryllium compounds, mainly beryllium oxide. The plant in which
these workers had been employed started operation in 1952. The first study of
these workers was made in 1963 when 130 men out of a group of 146, who had
worked for more than 6 months, were examined. Chest X-rays were taken and, in
all but one case, pulmonary function was measured by a set of respiratory
function tests. In a follow-up in 1973, 106 of the 130 were examined. In
another follow-up in 1977, only 8 men from that group and one ex-employee were
examined, but to this new group were added 24 employees and 14 ex-employees
employed since 1963. The same tests were performed on these subjects.
Airborne beryllium had been measured during the years 1952 to 1960, but
no measurements seemed to have been made since 1960. In a total of 3401
o
samples taken, only 20 exceeded the 25 pg/m limit and 318 exceeded the 2 |jg/
o
m limit. Mean concentrations were presented as geometric means, and in both
3
1952 and 1960 these concentrations were never above 2 pg/m . Generally, con-
3
centrations were far below 1 (jg/m . The 1963 study found 6 cases of definite
or suspected beryllium disease. The follow-up studies did not find any new
cases. However, after the 1977 study, two further cases were added. Both
were men who had worked since 1952. There were also two cases of acute
5-10
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TABLE 5-6. COMPARISON OF 1971 AND 1974 DATA OF WORKERS SURVEYED IN BERYLLIUM
EXTRACTION AND PROCESSING PLANTS*
Workers
Smokers
Ex-smokers
Nonsmokers
Total
Year
1971
1974
1971
1974
1971
1974
1971
1974
No.
55
55
36
36
20
20
111
111
Age
(years)
40.9
43.9
43.3
46.3
43.4
46.4
42.1
45.1
Ciga-
rette-
Pack-
years
23
27
25
25
0
0
23.5
26.2
Length of
Employ-
ment
(years)
10.2
13.2
10.6
13.6
10.9
13.9
10.4
13.4
FEVj (%
predicted)
92.9
90.4
97.9
97.7
105.3
102.4
96.7
95.1
FVC (%
predicted)
96.6
95.2
97.8
101.2
98.6
102.5
97.3
98.5
PEFR (%
predicted)
96.9.
91.3'
(P < 0.02)
100. 0+
94. 8T
(P = 0.02)
104.7
99.2
99.3
93. 8T
(P < 0.01)
Definition of abbreviations: FEVj - 1-sec forced expiratory volume; FVC = forced vital
capacity; PEFR - peak expiratory flow rate.
^Results are mean values.
Significant difference, comparing results in 1971 with those in 1974.
Source: Sprince et al. (1978)
TABLE 5-7. COMPARISON OF 1971 AND 1974 ARTERIAL BLOOD GAS RESULTS*
Workers
Smokers
Ex-smokers
Nonsmokers
Total
Year
1971
1974
1971
1974
1971
1974
1971
1974
No.
55
55
36
36
20
20
111
111
Pan
02
(mm Hg)
90.9.
96. 1'
89.1,
95.7'
93.4
100.2**
90.8,
96. 8T
PaC02
(mm Hg)
38.0,
35.1'
37.9
36. 1T
38.0
36.3
38.0,
35. 7T
PH
7.42
7.42
7.42
7.42
7.43,
7.41'
7.43
7.42**
Definition of abbreviations:
*
Results are mean values.
Pan = arterial P
OP' PaC02 = arterial PC02
**
< 0.01, comparing 1971 with 1974 results.
P < 0.05, comparing 1971 with 1974 results.
Source: Sprince et al . (1978)
5-11
-------
beryllium pneumonitis, and these two men were among a group of 17 who were
deemed to have had the highest exposures. Both these cases were normal in the
1963 study.
After adjusting for age, smoking, and other personal attributes, the
respiratory function tests only showed that exposure was related to large
vital capacity. In the 1963 study, a significant negative correlation between
estimated total exposure to beryllium and lung compliance was shown in a sub-
group of 19 workers from the slip-casting bay. Comparison between data from 1963
and 1973 showed only changes that could be ascribed to personal attributes.
The conclusion of the authors was that respiratory function studies generally
could not detect beryllium disease before radiographic changes appeared. De-
creases in lung function were only observed in cases with clear X-ray changes.
However, Preuss and Oster (1980) have noted that changes in vital capacity may
occur long before X-ray changes appear.
As mentioned above, chronic beryllium disease differs from some other
occupational lung diseases, in that it also has a systemic component. The
systemic involvement suggests that there is also an immunological component to
the disease and that hypersensitivity can explain some of the findings in
chronic beryllium disease.
In 1951, Curtis developed a patch test, which was found to be positive
for most cases of dermatitis and skin granuloma caused by beryllium. In
addition, it was found to be positive in many cases of lung disease caused by
beryllium (Curtis, 1959) and in beryllium-exposed workers (Nishimura, 1966).
However, it was also found that the patch test could initiate the development
of skin reactions or pulmonary disease in people exposed to beryllium, but who
had not had previous symptoms of respiratory illness (Sneddon, 1955; Stoeckle
et al., 1969; Rees, 1979; Cotes et al., 1983).
Recently, attempts have been made to develop other tests suitable for
studying hypersensitivity to beryllium. The lymphocyte transformation test,
as reported by Williams and Williams (1982a,b, 1983), is deemed to be the most
useful. This test gave a positive response in 16 patients with established
chronic beryllium disease, whereas it was negative in 10 subjects with suspec-
ted disease. Only two positive responses were reported among 117 healthy
beryllium workers (Williams and Williams, 1983). It is not clear, however, if
a positive test in an otherwise healthy worker really indicates that such an
individual is at a higher risk for getting pulmonary disease.
5-12
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In an area in Czechoslovakia where coal with a high beryllium content is
burned, Bencko et al. (1980) studied immunoglobulins and autoantibodies both
in workers in a power plant and in people living in the vicinity of the plant.
The concentration of beryllium in the town was estimated to be, on an average,
3
80 ng/m , which is 8 times higher than the suggested standard for ambient air
in the U.S. In both the workers and general public, elevated levels of immuno-
globulins IgG and IgA and increased concentrations of autoantibodies were
found, compared to a control group not exposed to beryllium. The workers had
higher exposure than the town dwellers, up to 8 ug/m , and they also had
considerably higher levels of IgM than the town residents or the control
group. Since many factors can contribute to increases in immunoglobulin levels,
the significance of these findings is not clear.
5.2.1.2 Animal Studies—There have been a large number of animal studies on
the chronic effects of beryllium exposure via air. Much of the early work in
the 1940's and 1950's has been described by Vorwald et al. (1966). A large
number of studies on the rat were performed by Vorwald and co-workers, but
many of these studies have never been fully reported and the main data base
remains the 1966 review by Vorwald and co-workers.
In one study, rats were exposed to beryllium sulfate aerosol in concentra-
3
tions ranging from 2.8 to 194 ug/m of air. The exposures were usually given
7 hours a day, for 1 to 560 days. It was stated that exposure to 2.8 ug/m
o
did not produce any specific inflammatory abnormalities, whereas 21 ug/m
caused significant inflammatory changes in some long-surviving rats. Forty-two
pg/m produced chronic pneumonitis and 194 pg/m caused acute disease.
The main finding of this study was that the low-exposure group had a high
incidence of pulmonary cancer, 13 of 21 rats. There has been some concern
about the validity of the low-exposure data, however (see Section 7.1.8.3). In
the group exposed to 42 pg/m , microscopic examination of lung tissue showed
alveolar changes with a large increase in macrophages. With longer exposure,
diffuse pneumonitis and focal granulomatous lesions became increasingly promi-
nent, typically occurring in patches.
Schepers et al. (1957) exposed rats to beryllium sulfate; the average
concentration of beryllium was about 35 ug/m . In one experiment 21 animals
were exposed for 1 to 30 days; in another experiment 115 animals were exposed
for 6 months. The number of controls was 17 and 69, respectively. In the
latter study, 46 animals out of the 115 died during exposure and 29 were
5-13
-------
killed at the end of exposure. Fifty-two rats were then transferred to normal
air and observed for up to 18 months after cessation of exposure. The cause
of death during exposure was mainly pleural pericarditis with a tendency to
chronic pneumonitis. No bacteria were isolated, but the authors concluded
that this response was caused by infection, since sulfathiazole had a benefi-
cial effect. In further experiments, similar exposures were given and no rats
died during exposure or up to 9 months following exposure. Among the findings
after 6 months of exposure were neoplastic changes, foam-cell clusters, focal
mural infiltration, lobular septal cell proliferations, peribronchial alveolar
wall epithelialization and granulomatosis.
In a study by Reeves et al. (1967), 150 rats (same number of controls)
were exposed to beryllium sulfate at a mean concentration of 34 ug/m .
Exposure was for 72 weeks, 7 hours/day, 5 days/week. Variations in the exposure
concentrations must have been large (some above 100 ug/m ) since the standard
3
deviation was reported to be about 24 ug/m . Every month, 3 male and 3 female
rats from the exposed and control groups were killed. Among the findings were
progressive increases in lung weight in the exposed animals. At the end of
the experiment, the lung weights of exposed animals were, on an average, more
than four times greater than those of controls. Histological examination
showed inflammatory and proliferative changes. Also, clusters of macrophages
in the alveolar spaces were a common finding. Granulomatosis and fibrosis
were only occasionally seen. The proliferative changes ultimately led to a
large number of tumors in the exposed animals (see Section 7.1.1).
Wagner et al. (1969) exposed two groups of 60 rats each to the beryllium
ores, beryl and bertrandite. Exposure was for up to 17 months to 15 mg/m of
3 3
the ores, corresponding to 210 ug beryllium/m as bertrandite and 620 ug/m as
beryl. Exposure was generally for 6 hours/day, 5 days/week. A very large
incidence of lung tumors was reported. Among the non-malignant changes, study
clusters of macrophages were seen. Granulomas were seen in lungs from bertran-
dite-exposed rats.
The last major study on the rat seems to be the study by Sanders et al.
(1975). They exposed rats to beryllium oxide particles calcined at 1,000°C.
Exposure to the beryllium oxide was via the nose only and all exposures were
single. Exposures ranged from 30 to 180 minutes and concentrations of beryl-
3
lium were from 1 mg to 100 mg/m . The single exposures resulted in chronic
changes characterized by the appearance of foamy macrophages and some granulo-
matous lesions. A significant depression of alveolar clearance was observed.
5-14
-------
Other animal studies have examined the effects of beryllium exposure on
monkeys (Vorwald et al., 1966; Schepers, 1964; Conradi et al., 1971), dogs
(Conradi et al., 1971; Robinson et al., 1968), guinea pigs (Policard, 1950;
Reeves et al., 1971, 1972) and hamsters (Wagner et al., 1969).
Vorwald et al. (1966) exposed monkeys to intermittent daily administra-
3
tions of beryllium sulfate (average concentration of 35 ug/m ) for several
months. Some monkeys were given intratracheal instillations of beryllium
oxide. Both routes of administration led to typical chronic beryllium disease
with pneumonitis and granulomatosis.
Schepers (1964) exposed three groups of monkeys, 4 in each group, to
aerosols of beryllium fluoride, beryllium sulfate, and beryllium phosphate in
3
concentrations of about 200 ug/m as beryllium. In another experiment, two
groups of monkeys, 4 animals in each, were given higher concentrations of the
beryllium phosphate, about 1140 and 8380 ug/m of beryllium, respectively.
Exposure was 1 or 2 weeks in the animals exposed to the fluoride and sulfate,
and from 3 days to 30 days in the groups exposed to the phosphate. After
exposure ceased, the animals were kept in normal air for different periods of
time.
There were signs of initial general toxicity, in the form of anorexia, in
the exposed animals. Dyspnea, one of the typical signs of human chronic
beryllium disease, developed rapidly in the animals exposed to fluoride and to
the high beryllium phosphate concentrations. After cessation of exposure,
some recovery was noted. Mortality was 100 percent in the animals exposed to
the two highest phosphate concentrations. Examination of lungs from animals
who either died during the experiment or were killed showed pulmonary edema and
congestion, mainly in the animals exposed to the fluoride and to the highest
phosphate concentration. Cor pulmonale was also a common finding. The his-
tological picture was similar to what has been seen in other experimental
animals and in human beings. Notable were pigment-filled macrophages and
invasion of plasma cells in the alveoli.
Wagner et al. (1969) exposed 2 groups of 12 squirrel monkeys each, for 23
months, to beryl and bertrandite dust under the same exposure conditions as
described for rats. While both dusts caused macrophage clusters, no other
marked changes were seen compared to the controls.
The effects of beryllium oxide calcined at 1400°C were studied by Conradi
et al. (1971). Five monkeys received inhalation exposures with concentrations
5-15
-------
3
varying between 3.3 and 4.4 mg beryllium/m . Exposure was for 30 minutes at
3 monthly intervals; the animals were observed for 2 years and then killed.
The results of histological examinations were essentially negative. No major
differences could be seen between controls and exposed animals.
Conradi et al. also studied 6 dogs exposed in the same way as the monkeys.
No pathological changes were observed in the dogs.
Robinson et al. (1968) gave much higher doses of beryllium to dogs. Two
dogs were exposed for 20 minutes to rocket exhaust products containing mixtures
of beryllium oxide, beryllium fluoride and beryllium chloride at average
3
concentrations of 115 mg beryllium/m . The dogs were observed for a period of
3 years, and then killed. Immediately after exposure the dogs had some acute
symptoms, but during the rest of the study they remained clinically healthy.
Histological examination of the lungs showed small foci of granulomatous
inflammation scattered throughout the lungs of both dogs. Beryllium deposits
were also found in the lungs. The average beryllium content of the lungs of
these 2 dogs was 3.9 and 5.5 mg/kg wet weight, respectively.
Granulomatosis has also been shown in guinea pigs exposed to beryllium
oxide dust (Policard, 1950; Chiappino et al., 1969). In the guinea pig, it
has been possible to produce beryllium sensitivity, and this seems to have
some protective effect against the development of pulmonary disease (Reeves
et al., 1971; Reeves et al., 1972). Barna et al. (1981) studied two strains
of guinea pigs given intratracheal injections of 10 mg of beryllium oxide.
All of the animals in one strain developed lung disease, whereas the animals
in the other strain did not, indicating genetic differences. The latter
animals also showed negative skin tests and lymphocyte transformation tests,
whereas positive reactions were seen in the group with the lung reactions.
Administration of the immunosuppressive drug, prednisone, had a beneficial
effect on the animals with lung disease; however, this effect only lasted as
long as the treatment with the drug continued. Following cessation of the
drug, the lung disease reappeared, demonstrating the persistence of beryllium
in the lung.
Wagner et al. (1969) exposed two groups of hamsters, 48 animals in each
group, for 17 months to beryl and bertrandite dust under the same exposure
conditions previously described for rats and squirrel monkeys. After 6 months
of exposure, the bertrandite-exposed animals had a few granulomatous lesions
in the lungs, and, in both groups, there were some atypical cell proliferations.
5-16
-------
Interestingly, in the various studies which have shown differing degrees
of granulomatosis in rats, it is noteworthy that rats have not developed
hypersensitivity to beryllium (Reeves, 1978).
There have also been some studies where animals have been orally exposed
to beryllium for long periods. In some early studies (Guyatt et al., 1933;
Jacobson, 1933; Kay and Skill, 1934), rickets were produced in young animals
by giving large oral doses of beryllium carbonate (0.1-0.5 percent; 1000-
5000 mg/kg) in the diet. This effect has since been regarded as an indirect
effect due to the binding of phosphate to beryllium in the gut and phosphorus
depletion in the body.
Schroeder and Mitchener (1975a,b) gave groups of male and female rats and
mice beryllium in drinking water at a concentration of 5 mg/1 for their respec-
tive lifetimes. No consistent differences could be noticed between exposed
animals and controls with regard to weight and lifespan. In a 2-year feeding
study, Morgareidge et al. (1977, abstract) fed rats dietary concentrations of
5, 50, and 500 mg beryllium/kg. The highest dose level resulted in a slight
weight depression. Specific details about the results were not reported.
A large number of experiments have been conducted on beryllium compounds
injected into animals. Some of these studies are mentioned in Section 7.1 on
experimental carcinogenicity. The results from some of these studies have
also been presented in earlier documents on beryllium, especially with regard
to effects on enzymes (Drury et al., 1978). Since these exposure routes are
not relevant for understanding the action of beryllium in humans, they will
not be discussed further in this document.
5.2.2 Teratogenic and Reproductive Effects of Beryllium
5.2.2.1 Human Studies—No known studies have been reported concerning the
teratogenic and reproductive effects of beryllium exposure in humans.
5.2.2.2 Animal Studies—Very few studies have investigated the teratogenic or
reproductive effects produced by beryllium exposure of animals. The available
information consists of one study evaluating the behavioral effects of offspring
exposed to beryllium sulfate during pregnancy (Hirotoda and Hoshishima, 1979),
a study dealing with the ability of beryllium chloride to penetrate the placenta
(Bencko et al., 1979), and a study concerned with the effects of beryllium
chloride on developing chick embryos (Puzanova et al., 1978).
5-17
-------
Hoshishima et al. (1978) presented a brief abstract and, later, a more
extensive report (Tsujii and Hoshishima, 1979) on the effects of trace quanti-
ties of beryllium injected into pregnant CFW strain mice. Six females per
group were exposed to a total of 22 kinds of metals which included BeSO. (140
ng/mice/day). The mice received intraperitoneal injections (0.1 ml) 11 times
during pregnancy. The injections were given once daily for three consecutive
days and then every other day for eight treatments. The gestational days of
treatment were not reported. In this study, beryllium (140 ng/day) produced
the following differences in the pups exposed i_n utero as compared to the
control group: delayed response in head turning in the geotaxis test, accelera-
tion in the straight-walking test, delayed bar-holding (for a moment) response,
and acceleration of bar holding (for 60 seconds).
The authors suggested that trace elements may have stimulating effects on
physiological processes if given in concentrations similar to those found in
nature, but if greater concentrations are given, then the effect could be
irritating. However, the results of this study are too equivocal to confirm
or deny this possibility. Further studies, using more than one dose level,
would have to be conducted to establish this hypothesis. In addition, more
basic research on the significance of the behavioral responses must be done in
order to understand whether an acceleration or diminution of the various
responses represents a true adverse effect.
In a study by Bencko et al. (1977), the soluble salt of beryllium, BeCl^,
was evaluated for its ability to penetrate the placenta and reach the fetus.
Radiolabelled BeCK was injected into the caudal vein of 7 to 9 ICR SPF mice
and was administered in 3 different time periods: (1) before copulation (group
A), (2) the 7th day of gestation (group B), and (3) the 14th day of gestation
(group C). The animals were sacrificed on the 18th to 19th day of pregnancy
and the radioactivity associated with the fetal and maternal compartments was
evaluated. In fetuses exposed on the 14th day of gestation, higher levels of
radioactivity were associated with the fetal compartment as compared to other
exposure periods (group A, 0.0002 ug Be/g fetus; group B, 0.0002 ug Be/g
fetus; and group C, 0.0013 ug Be/g fetus). The amount of radioactivity in
the other organs of the fetus was generally not influenced by beryllium exposure
except in the spleen and liver. The amount of Be penetrating the spleen was
decreased, while in the liver it was increased when Bed was given on the
14th day of pregnancy.
5-18
-------
Puzanova et al. (1978) conducted studies on the effects of beryllium on
the development of chick embryos. BeCl? (300 ug to 0.00003 ug dissolved, in
3 ul twice-distilled water) was injected subgerminally into chick embryos (10
embryos per dose) on the second day of embryogenesis. After a 24-hour incuba-
tion, the eggs were opened and stained with 0.1 percent neutral red so that
the distance between the origin of the vitelline arteries and the caudal tip
of the body could be measured. In a second part of this experiment, the same
doses of Bed2 were administered subgerminally to 2-day embryos, and intra-
amniotically to 3- and 4-day embryos. The surviving embryos were examined
after the 6th day of incubation.
In the first part of the experiment, it was found that 300 ug BeCK
caused complete embryo!ethality while 0.3 ug was not lethal to any embryos.
Doses of 0.003 (jg and under had no observable effect on the development of the
embryos. When the eggs were treated on day 2, the most common malformation
was caudal regression and open abdominal cavity and ectopia cordis. When
administered on the fourth day, execephalia, mandibular malformation, and
malformations described as the straitjacket syndrome were reported. It is not
known, however, if these types of teratogenic effects in chick embryos are
reflective of effects that might occur in humans. Additional studies would
have to be done using mammals to determine whether beryllium has teratogenic
potential.
Considered collectively, the available information from the above studies
is not sufficient to determine whether beryllium compounds have the potential
to produce adverse reproductive or teratogenic effects. It should be noted
that these studies were not designed to specifically investigate the effects
of beryllium compounds on reproduction or the developing conceptus. Further
studies in this area would be desirable.
5-19
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6. MUTAGENIC EFFECTS OF BERYLLIUM
Beryllium has been tested for its ability to cause genetic damage in both
prokaryotic and eukaryotic systems. The prokaryotic systems include gene
mutations and DNA damage in bacteria. The eukaryotic systems include DNA
damage and gene mutations in yeast and cultured mammalian cells, and studies
for chromosomal aberrations and sister chromatid exchanges in mammalian cells
i_n vitro. The available literature indicates that beryllium has the potential
to cause gene mutations, chromosomal aberrations, and sister chromatid exchange
in cultured mammalian somatic cells.
6.1 GENE MUTATIONS IN BACTERIA AND YEAST
The studies on beryllium-induced gene mutations in bacteria and yeast are
summarized in Table 6-1.
6.1.1 Salmonella Assay
Beryllium has been tested for its ability to cause reverse mutations in
Salmonella typhimurium (Simmon, 1979a; Rosenkranz and Poirier, 1979).
Simmon (1979a) found that beryllium sulfate was not mutagenic in Salmonella
strains TA1535, TA1536, TA1537, TA98, and TA100. Agar incorporation assay
with and without S-9 metabolic activation was employed. The highest concentra-
tion of beryllium sulfate tested was 250 ug/plate (1.41 umole). No mutagenic
response was obtained in any of the above strains.
Beryllium sulfate was also not mutagenic in Salmonella typhimurium strains
TA1535 and TA1538, both in the presence and absence of S-9 activation system
(Rosenkranz and Poirier, 1979). Two concentrations of the test compound used
were 25 ug/plate and 250 ug/plate. No significant differences in the mutation
frequencies between the experimental and the control plates were noted.
6.1.2 Host-Mediated Assay
Negative mutagenic response of beryllium sulfate was obtained in the
host-mediated assay (Simmon et al., 1979). Several procedures were used. In
all procedures the tester strain was injected intraperitoneally and the beryl-
lium sulfate was given orally or by intramuscular injection. Four hours
later, the Salmonella or Saccharomyces tester strain was recovered from the
6-1
-------
TABLE 6-1. MUTAGENICITY TESTING OF BERYLLIUM: GENE MUTATIONS IN BACTERIA AND IN YEAST
Test System
Salmonel la
typhimurium
Salmonella
„, typhimurium
i
IXi
Saccharomyces
cerevisiae
Salmonel la
typhimurium
Escherichia
coli
Escherichia
coli
(pol assay)
Strain
TA1535
TA1536
TA1537
TA100
TA98
TA1530
TA1538
TA1535
D3
TA1535
TA1538
WP2
Pol A+
Pol A"
Concentration of S-9 Activation
Test Compounds System
Maximum of ±
250 ug/plate
25 mg/kg i.m. Host-mediated
assay in mice
1200 mg/kg gavage
1200 mg/kg gavage
25 ug/plate ±
250 ug/plate
0.1-10 umol/plate
(0.9-90 (jg/plate)
250 ug/plate
+
Results
Reported
negative
in al 1
strains
Reported
negative
in all
strains by
both routes
of exposure
Reported
negative
Reported
negative
Reported
negative
Comments Reference
1. Only highest Simmon, 1979a
concentration
used.
Simmon et al. ,
1979
Rosenkranz and
Poirier, 1979
Ishizawa,
1979
Rosenkranz and
Poirier, 1979
-------
peritoneal cavity and plated to determine the number of mutants (Salmonella)
or recombinants (Saccharomyces) and the number of recovered microorganisms.
Simultaneous experiments were conducted with control (untreated) mice. Using
25 mg/kg given intramuscularly, beryllium sulfate was not mutagenic with
tester strain TA1530 or TA1538. Using 1200 mg/kg given orally, beryllium
sulfate was not mutagenic in TA1535 and did not significantly increase the
recombination frequency in S. cerevisiae D3.
6.1.3 Escherichia coli WP2 Assay
Negative mutagenic response in the Escherichia coli WP2 system was obtained
with beryllium concentrations ranging from 0.1-10 ^mol/plate (10.5 - 105 jjg/
plate) (Ishizawa, 1979).
These results should not be taken as proof, however, that beryllium is
nonmutagenic. The standard test system may be insensitive for the detection
of metal mutagens because of the large amount of magnesium salts, citrate, and
phosphate in the minimal medium (McCann et al., 1975). Bacteria appear to be
selective in letting metal ions get inside their cells. More research is
needed to select a suitable strain of bacteria to detect metal-induced muta-
genesis in these prokaryotic systems.
6.2 GENE MUTATIONS IN CULTURED MAMMALIAN CELLS
The ability of various beryllium compounds to cause gene mutations in
cultured mammalian cells has been investigated by Miyaki et al. (1975) and
Hsie et al. (1979a,b) (Table 6-2).
Miyaki et al. (1975) demonstrated the induction of 8-azaguanine-resistant
mutants by beryllium chloride in the Chinese hamster V79 cells. Beryllium
chloride at concentrations of 2 and 3 mM (158 (jg/ml and 237 ug/ml, respectively)
induced 35.01 ± 1.4 and 36.5 ±1.7 mutant colonies per 10 survivors. These
values were approximately 6 times higher than the control value of 5.8 ± 0.8
colonies per 10 survivors. The cell survival rates were 56.9 percent at 2 mM
concentration and 39.4 percent at 3 mM. Analysis of mutant colonies revealed
that they were deficient in the enzyme hypoxanthine guanine phosphoribosyl
transferase (HGPRT) activity indicating that the mutation had occurred at the
HGPRT locus.
Hsie et al. (1979a,b) also reported that beryllium sulfate induced 8-
azaguanine-resistant mutants in Chinese hamster ovary (CHO) cells. However,
6-3
-------
TABLE 6-2. MUTAGENICITY TESTING OF BERYLLIUM: GENE MUTATIONS IN MAMMALIAN CELLS IN VITRO
CTi
I
Test System
Chinese
hamster
Chinese
hamster
Strain
V79 cells;
resistance
to 8-
azaguanine
CHO cells;
resistance
to 8-
azaguani ne
Concentration of S-9 Activation
Test Compounds System
2 mM (10 ug/ml) None
3 mM (15 ug/ml)
beryl lium chloride
Not stated ±
Results
Reported
positive
6.0 to
6.3-fold
increase
Reported
mutagenic
and weakly
mutagenic
Comments
1. 99 percent
pure.
2. No dose
response.
1. No details.
2. The authors
noted variable
results with
Reference
Miyaki et al . ,
1975
Hsie et al . ,
1979 a,b
noncarcinogens
such as calcium.
-------
they did not provide details about the concentrations of the test compound and
the number of mutants induced per 10 survivors.
These studies indicate that beryllium has the ability to cause gene
mutations in cultured mammalian cells.
6.3 CHROMOSOMAL ABERRATIONS
Beryllium sulfate was tested for its clastogenic potential in cultured
human lymphocytes and Syrian hamster embryo cells (Larramendy et al., 1981)
(Table 6-3). Cultured human lymphocytes (24 hours old) were exposed to a
single concentration, 2.82 x 10 M (5 ug/ml), of beryllium sulfate, and chromo-
some preparations were made 48 hr after the treatment. A minimum of 200 meta-
phases were scored for chromosomal aberrations. In cultures treated with
beryllium, there were 19 cells (9.5 percent) with chromosomal aberrations, or
0.10 ± 0.02 aberration per metaphase. In the nontreated control cells, only 3
cells (1.5 percent) had chromosomal aberrations. This sixfold increase in the
aberration frequency clearly indicates that beryllium sulfate is clastogenic
in cultured human lymphocytes. A beryllium concentration of 2.82 x 10 M was
selected because it induced a maximum number of sister chromatid exchanges in
human lymphocytes in another experiment reported by the same authors (see
Section 6.4).
In the Syrian hamster embryo cells the results were even more dramatic.
This same concentration of beryllium sulfate 24 hr after the treatment induced
aberrations in 38 out of 200 cells (19 percent). Aberration per metaphase was
0.12 ± 0.03. In control cells only 3 cells (1.5 percent) had aberrations or
0.01 ± 0.01 aberration per cell. In these studies, chromosomal gaps were also
considered as aberrations. Even if the gaps were not included as true aberra-
tions, the aberration frequency was still far above the control level, indica-
ting that beryllium sulfate has a clastogenic potential in cultured mammalian
cells.
6.4 SISTER CHROMATID EXCHANGES
Larramendy et al. (1981) also studied the potential of beryllium to
induce sister chromatid exchanges (Table 6-3). Both cultured human lymphocytes
and Syrian hamster embryo cells were employed in these studies.
Lymphocytes after 24 hr of cultivation were exposed to 5.6 x 10 M (1.0
ug/ml), 1.41 x 10"5M (2.5 ug/ml) and 2.82 x 10~5M (5 ug/ml) of beryllium sulfate
6-5
-------
TABLE 6-3. MUTAGENICITY TESTING OF BERYLLIUM: MAMMALIAN IN VITRO CYTOGENETICS TESTS
Test System
Chromosomal
aberrations
Chromosomal
aberrations
CT>
cn Sister
chromatid
exchanges
Sister
chromatid
exchanges
Strain
Human
lymphocytes
Syrian
hamster
embryo
cells
Human
lymphocytes
Syrian
hamster
embryo
cells
Concentration of S-9 Activation
Test Compounds System
2.82 x 10~5M
(5 pg/ml)
2.82 x 10~5M
(5 pg/ml)
5.6 x 10"6M
(1 pg/ml) ,
1.41 x 10 DM
(2.5 jjg/mU
2.82 x 10
(5 ug/ml)
5.6 x 10"6M
(1 pg/ml).
1.41 x 10 M
(2.5 pg/mU
2.82 x 10 °M
(5 pg/ml)
Results
Reported
positive
Reported
positive
Reported
positive
Reported
positive
Comments
1. 6x above
background level.
2. Primarily
breaks.
1. 12x above
background level.
2. Primarily
breaks and gaps.
1. Less than two-
fold increase.
2. Insufficient
evidence for a
positive conclu-
sion.
1. Less than two-
fold increase.
2. Insufficient
evidence for a
positive conclu-
sion.
Reference
Larramendy
et al . , 1981
Larramendy
et al . , 1981
Larramendy
et al . , 1981
Larramendy
et al . , 1981
-------
followed by 10 |jg Brdllrd/ml medium. Cultures were incubated for an additional
48 hr and chromosome preparations were made and stained for sister chromatid
exchange analysis. At least 30 metaphases were scored for each concentration
of the test compound. The background sister chromatid exchange level was
11.30 ± 0.60. According to these investigators, there was a dose-dependent
increase in sister chromatid exchanges, i.e., 17.75 ± 1.10, 18.15 ± 1.79, and
20.70 ± 1.01, respectively, for the above concentrations.
In the Syrian hamster embryo cells, the same concentrations of beryllium
sulfate induced 16.75 ± 1.52, 18.40 ± 1.49, and 20.50 ± 0.98 sister chromatid
exchanges. The background sister chromatid exchange frequency was 11.55 ± 0.84.
The sister chromatid exchange assay has been extensively used in mutagenicity
testing because of its sensitivity to many mutagenic chemicals.
The authors stated that the results of the sister chromatid exchange
studies in human lymphocytes and Syrian hamster embryo cells demonstrated a
dose-response relationship. However, in these studies, the increase was less
than twofold and fell within a plateau region; thus, the dose-response rela-
tionship suggested by the authors may be somewhat tenuous. Further experimen-
tation to confirm the study results would be advisable.
6.5 OTHER TESTS OF GENOTOXIC POTENTIAL
6.5.1 The Rec Assay
Kanematsu et al. (1980) found beryllium sulfate to be weakly mutagenic in
the Rec assay. Bacillus subtil is strains H17 (rec ) and M75 (rec ) were
streaked onto agar plates. An aqueous solution (0.05 ml) of 0.01 M (88.5
Mg/plate) beryllium sulfate was added to a filter paper disk (10-mm diameter)
which was placed on the plates at the starting point of the streak. Plates
were first cold incubated (4°C) for 24 hr and then incubated at 37°C overnight.
Inhibition of growth, due to DNA damage, was measured in both the wild type
H17 (rec ) and the sensitive type (rec ) strains. The difference in growth
inhibition between the wild-type strain and the sensitive strain was 4 mm,
which was considered to indicate a weak mutagenic response. Similar results
were also obtained by Kada et al. (1980).
6.5.2 Pol Assay
Beryllium was tested for mutagenicity in the pol assay using Escherichia
coli (Rosenkranz and Poirier, 1979, 1980). Use for this assay is based on the
6-7
-------
fact that cells deficient in their ability to repair DNA damage are more
sensitive than normal cells to the growth-inhibiting properties of mutagenic
agents. Escherichia coli strains pol A (normal ) and pol A (DNA polymerase
I-deficient) were grown on agar plates, and filter disks impregnated with
250 (jg of beryllium sulfate were placed in the middle of each agar plate and
incubated at 37°C for 7-12 hrs. Experiments were conducted both in the presence
and absence of S-9 activation system. The diameter of the zones of growth
were determined in both strains. There was no difference in the diameter of
the zones of growth in both strains. Positive and negative controls were used
for comparison. The shortcomings of this assay are that (1) interpretable
conclusions can be drawn only when measurable zones of growth inhibition
occur; (2) it is possible that the test chemical may not be able to penetrate
the test organisms; and (3) insufficient diffusion of chemicals from the disk
can occur because of low solubility or large molecular size.
6.5.3 Hepatocyte Primary Culture/DMA Repair Test
The DNA damage and repair test as reflected in unscheduled DNA synthesis
(incorporation of tritiated thymidine) was conducted using beryllium sulfate
(Williams et al., 1981). Rat primary hepatocyte cultures were exposed to 0.1,
1, and 10 mg/ml of beryllium sulfate with 10 uc/ml of tritiated thymidine and
incubated for 18-20 hr. Following incubation, autoradiographs of cells were
prepared. A minimum of 20 nuclei was counted for each concentration and the
uptake of radioactive label was measured as grain counts in each nucleus. The
compound was considered positive when the nuclear grain count was greater than
that of the control (above 5 grains per nucleus over the control value). The
compound was considered negative in the assay if the nuclear grain count was
less than 5 at the highest nontoxic dose. Cytotoxicity was determined by the
morphology of the cells. According to these authors, beryllium sulfate did not
induce statistically greater grain count at any of the above concentrations
over the control value. Benzo(a)pyrene was employed as a positive compound.
6.5.4 Beryllium-Induced DNA Cell Binding
Kubinski et al. (1981) reported that beryllium induces DNA protein com-
plexes (adducts) that can be measured with analytical techniques. Escherichia
coli cells and Ehrlick ascitis cells were treated with radioactive DNA in the
presence of 30 jjM of beryllium. Methyl methanesulfonate (MMS) was used as a
6-8
-------
positive control. The negative control consisted of cells only and radioactive
DNA. The radioactive DNA bound to cell membrane proteins was measured. Like
MMS, beryllium induced positive results. However, the significance of beryllium-
induced DNA binding to cell membranes is not clear in terms of its ability to
induce mutations.
6.5.5 Mitotic Recombination In Yeast
Beryllium sulfate did not induce mitotic recombination in the yeast
Saccharomyces cerevisiae D., (Simmon, 1979b). The Saccharomyces cerevisiae
strain D, is a heterozygote with mutations in ade 2 and his 8 of chromosome
XV. When grown on a medium containing adenine, cells homozygous for the ade 2
mutation produce a red pigment. These homozygous mutants can be generated
from the heterozygotes by mitotic recombination induced by mutagenic compounds.
A single concentration (0.5 percent) of beryllium induced 10 mutant colonies
per 10 survivors, while in the control the mutation frequency was 6 colonies
per 10 . In the mitotic recombination assay, there must be a 3-fold increase
in the mutation frequency of experimental over the control in order to be
considered as a positive mutagenic response. The negative mutagenic response
of beryllium may be due to the fact that it is not able to penetrate into the
cell as in other microbial tests.
6.5.6 Biochemical Evidence of Genotoxicity
Iji vitro exposure of rat liver cells to beryllium resulted in binding of
beryllium to non-histone proteins that were phosphorylated (Parker and Stevens,
1979). Exposure of rat hepatosoma cells in tissue culture to beryllium reduced
glucocorticoid induction of tyrosine transaminase activity (Perry et al. ,
1982). In a DNA fidelity assay, beryllium increased the mis incorporation of
nucleotide bases in the daughter strand of DNA that was synthesized i_n vitro
from polynucleotide templates by microbial DNA polymerase (Zakour et al.,
1981). Beryllium was investigated for its effects on the transcription of
calf thymus DNA and phage T^ DNA by RNA polymerase from E. coli under controlled
conditions. Beryllium inhibited overall transcription but increased RNA chain
irritation, indicating the interaction of the metal with the DNA template
(Niyogi et al., 1981).
6.5.7 Mutagenicity Studies in Whole Animals
Information on the mutagenicity of beryllium compounds in intact animals
such as Drosophila and mammals is not available in the literature. Such
6-9
-------
studies are highly valuable in assessing the in v ivo effects of beryllium
compounds, specifically to understand whether or not they induce mutations in
germ cells. Metals such as cadmium and methyl mercury have been implicated in
the induction of aneuploidy (numerical chromosomal aberrations) in female
rodent germ cells. Aneuploidy is generally induced as a result of malfunction-
ing of the spindle apparatus. Such studies with beryllium compounds would
yield valuable results.
6-10
-------
7. CARCINOGENIC EFFECTS OF BERYLLIUM
The purpose of this section is to provide an evaluation of the likelihood
that beryllium is a human carcinogen and, on the assumption that it is a human
carcinogen, to provide a basis for estimating its public health impact, includ-
ing a potency evaluation in relation to other carcinogens. The evaluation of
carcinogenicity depends heavily on animal bioassays and epidemiologic evidence.
However, information on mutagenicity and mechanisms of action, particularly in
relation to interaction with DNA and to metabolic and pharmacokinetic behavior,
has an important bearing on both the qualitative and quantitative assessment
of carcinogenicity. The available information on these subjects is reviewed
in other sections of this document. This section presents an evaluation of
animal bioassays, human epidemiologic evidence, the dose-response (quantita-
tive) aspects of assessment, and finally, a summary and conclusions dealing
with all of the relevant aspects of the carcinogenicity of beryllium.
7.1 ANIMAL STUDIES
Numerous animal studies have been performed to determine whether or not
beryllium and beryllium-containing substances are carcinogenic. In these
studies, metallic beryllium, salts of beryllium, and beryllium-containing
alloys and ores were administered by various routes. In the discussions that
follow, the studies are grouped according to the routes of administration
used.
7.1.1 Inhalation Studies
The first finding of pulmonary tumors after inhalation exposure to beryl-
lium was reported by Vorwald in 1953. Among 15 female rats exposed to beryl-
o
lium sulfate (BeSO^) aerosol at a reported concentration of 33 ug beryl!ium/m ,
7 hours/day, 5.5 days/week, 4 developed primary pulmonary adenocarcinomas.
The incidence represented 80 percent (4/5) of animals necropsied after 420
days of exposure and 50 percent (4/8) of animals necropsied after one year or
more. The paper reporting this study was read before a meeting of the American
Cancer Society, but was never published; an abstract of the presentation was
printed 2 years later (Vorwald et al., 1955). Schepers et al. (1957) published
a paper updating the Vorwald et al. study, which then encompassed 136 rats, of
which 78 survived to planned necropsy. The total number of tumors produced
7-1
-------
was counted, rather than the number of tumor-bearing animals. These tumors
totaled 76 after the animals had had 6 months of exposure to the beryllium
sulfate aerosol and up to 18 months of continued life in normal air. Eight
histologic variants of neoplasms were observed, intrathoracic metastases were
noted to occur, and successful transplants were claimed to have been accom-
plished.
During the late 1950s and early 1960s, both Schepers and Vorwald contin-
ued these experiments on what appears to have been a fairly large scale, but
instead of writing papers on them in the customary way, the results were
hinted at, or partially incorporated into reviews (Schepers, 1961; Vorwald et
al., 1966). The details of these experiments are, therefore, not in the public
record. Based on all available information, the best estimates are that Schepers
exposed rats to beryllium phosphate and obtained a tumor incidence of 35-60/170
at 32-35 ug beryllium/m3 and 7/40 at 227 ug beryl!ium/m3 (20-35 percent and
17.5 percent, respectively); after exposure to beryllium fluoride he obtained
3
a tumor incidence of 10-20/200 at 9 ug beryllium/m (5-10 percent), and after
exposure to zinc beryllium manganese silicate (ZnEeMnSiO,) (a fluorescent
phosphor in use at that time) he obtained a tumor incidence of 4-20/220 at
o
0.85-1.25 mg beryl!ium/m (2-9 percent, Table 7-1). No tumors were observed
in rabbits and guinea pigs similarly exposed.
In all but one of his inhalation experiments, Vorwald used rats exposed
to beryllium sulfate aerosol in concentrations ranging from 2.8 to 180 ug
3
beryl!ium/m on various exposure schedules ranging in length from 3 months to
24 months. In one inhalation experiment, beryllium oxide (temperature of
3
firing not known) was used at 9 mg/m . Pulmonary lesions believed to be
adenocarcinomas were found in all groups, in incidences ranging from 20 to
100 percent, with weak correlations between incidence and exposure concentra-
tion and between incidence and exposure length (Table 7-2). No metastases
were observed. Serial homotransplants were attempted and were unsuccessful.
Reeves et al. (1967) exposed 150 rats of both sexes, and an equal number
of controls, to beryllium sulfate aerosol at a mean atmospheric concentration
o
(±1 S.D.) of 34.25 ± 23.66 ug beryl lium/m on a schedule of 35 hours/week.
Scheduled sacrifices were conducted quarterly. The first lung tumors were
seen at 9 months' exposure, and all animals necropsied at 13 months (43/43)
had pulmonary adenocarcinomas. Essentially similar results were reported by
Reeves and Deitch (1969) 2 years later for another animal group. In the
latter study, 225 female rats were exposed for durations of 3 to 18 months to
7-2
-------
TABLE 7-1. PULMONARY CARCINOMA FROM BERYLLIUM PART 2
Author
SCHEPERS
REEVES
WAGNER
Year
1957
1961
1964
1967
1969
1972
1976'
1969
Species
Rait
Rabbits
Guinea pigs
Monkeys
Rats
Guinea pigs
Rats
Hamsters
Monkeys
Compound
BeSO«
Be phosphate
BeFi
Zn. Be, Mn
silicate
RaCO«
BeFi
Be phosphate
BeSO«
Beryl
Bertrandilo
Beryl
Bertrandlte
Beryl
Bertrandite
Duration
of
Exposure
6-9 mo.
1-12 mo.
6-15 mo.
1-9 mo.
24 mo.
22 mo.
12 mo.
8 mo.
13 mo.
3 mo.
6 mo.
9 mo.
12 mo.
18 mo.
18-24 mo.
mmn
Atmospheric
Concentration
Be
32-35 r/m1
227 r/m1
9 r/m1
0.85-1. 25 mg/m1
1 mg/m1
35 r/m1
35 200 r/m1
180 r/m1
0.2 mg/m1
1.1 mg/m1
8.3 mg/m1
34.25 ± 23.66 r/m1
35.66 ± 13.77r/m»
3.7-30.4 r/m1
-15 r/m1
620 r/m1
2 10 r/m1
620 r/m1
2 1O r/m»
620 r/m1
210 r/m1
Incidence of
Pulmonary
Carcinoma
58? in 136
ca. 35 60 in 170
ca. 7 in 40
ca. 10- 12 in 200
ca. 4-2O in 220
0
0
0
Oin4
Oin4
Oin4
1 in 4
Oin4
43 in 43
19 in 22
33 in 33
15 in 15
21 in 21
13 in 15
Oin 58
0 in 110
18 in 19
0 in 30-60
Oin48
Oin48
Oin t2
Oin 12
•unpublished
Source: Reeves (1978)
7-3
-------
TABLE 7-2. PULMONARY CARCINOMA FROM BERYLLIUM PART 1
Author
VORWALD
Year
I960
1953
1955
1962*
1966
1968
Specie*
Rabbits
Rata
Guinea pig*
Rata
Monkeys
Compound
Zn. Be. Mn
silicate
Be stearate
BeJOH),
Be metal
BeO
BeSO«
BeO
BeSO«
BeO
Mode of
Administration
or
Duration of
Exposure
Inl
1
ratracheal
njection
Intratracheal
inj. in 3 doses
s4
:?
i!
8 *
ft
Inhalation
35-38 hrs/
Inhal.
ev 16
hrs/wk
12 14 mo
13-18 mo.
3-18 mo.
12 mo.
3-22 mo.
8-21 mo.
9-24 mo.
11-16 mo.
8 21 mo.
9-24 mo
13-16 mo.
3 12 mo.
18 mo.
18 mo.
3 * yrs.
Bronchomural
implant * intra-
bronchial inj.
Dose
or
Aim. Cone.
(Bel
2.3-6.9 mg
0.46 mg
3.4 mg
5 mg
31 mg
54 mg
75 mg
338 r
33 r
33-35 r/mg*
65 r/mg»
180r/m»
18r/m»
1. 8-2.0 r/m>
gmg/m1
21-42r/mJ
28K/m»
38 8 r/m1
I8-9O* mg
Incidence ol
Pulmonary
Carcinoma
0
0
0
0
0
0
0
1 in 4
1 in 5
4 in 8
17 in 17
55 in 74
11 in 27
72 in 1O3
31 in 63
47 in 90
9 in 21
25 in 50
43 in 95
3 in 15
22 in 36
"almost all"
13 In 21
Bin 11
3 in 2O
'unpublished
Source: Reeves (1978)
7-4
-------
3
35.66 ± 13.77 (jg beryllium/m (35 hours/week) at various age levels (Figure 7-1).
It was found that tumor yield depended not on length of exposure but on how
early in life the exposure was received. Rats exposed at an early age for
only 3 months had essentially the same tumor frequency (19/22) as rats exposed
for the full 18 months (13/15), whereas rats receiving 3 months' exposure
later in life had substantially reduced tumor counts (3-10/20-25; 86-87 percent
versus 15-40 percent). Generally, an incubation time of at least 9 months
after commencement of exposure was required to produce actual tumors, whereas
epithelial hyperplasia of the alveolar surfaces commenced after about 1 month,
progressed to metaplasia by 5-6 months, and to anaplasia by 7-8 months. In
guinea pigs, 18 months of exposure (35 hours/week) to three different concen-
3
trations of beryllium sulfate (3.7 ± 1.5 pg beryllium/m , 16.6 ± 8.7 pg
3 3
beryllium/m , and 30.4 ± 10.7 pg beryllium/m ) produced no tumors, but only
alveolar hyperplasia/metaplasia in 23 out of 144 animals, all of them associ-
ated with diffuse interstitial pneumonitis. Incidence of hyperplasia/metaplasia
in unexposed controls was 3/55 (Reeves et al., 1971, 1972; Reeves and Krivanek,
1974). Sanders et al. (1978) exposed female rats to submicron aerosols of
medium-fired (1000°C) beryllium oxide by the nose-only method. Only 1 of 184
rats developed a lung tumor during the 2-year observation period; alveolar
deposition was 1-91 pg beryllium with a half-time of 325 days.
Wagner et al. (1969) exposed rats, hamsters, and squirrel monkeys to
aerosols of beryl ore and bertrandite ore at the then "nuisance limit" for all
3
dusts (15 mg/m ). At this particle concentration, the beryllium content of
3
the aerosols was 620 and 210 pg/m for beryl and bertrandite, respectively.
Exposure was continued intermittently for 17 months. At that point, 18 of 19
rats exposed to beryl dust had bronchiolar or alveolar cell tumors, of which 7
were judged to be adenomas, 9 adenocarcinomas, and 2 epidermoid tumors.
Metastases were not observed, and transplants were not attempted. In the
animals exposed to bertrandite dust, and in all hamsters and squirrel monkeys,
no indisputable tumors were found. In the bertrandite-exposed rats and ham-
sters, granulomatous lesions composed of large, tightly packed macrophages as
well as "atypical proliferation" of the cells lining the respiratory bronchi-
oles and alveoli were seen. Atypical proliferation was also seen in beryl-
exposed hamsters, and, according to the authors, these proliferations "could
be considered alveolar cell tumors except for their size." Only the granulo-
matous lesions were seen in both beryl- and bertrandite-exposed monkeys.
7-5
-------
I
en
A
B
C
D
E
F
G
H
I
AGE MO,
EXP. HRS.
M
|A|M|jjj|A|S[O|N|D|j|F|M|A|M|j|j|A|S|O|N|D|j|F|lvi'
16 18 20 22 24
400
800
1200
1600 2000
2400 (CHAMBER TIMER)
[ EXPOSURE TO 35y Be (as SO4)/m3
35 Hrs./Wk.
• ANIMAL LOST
A NO TUMOR
a SMALL TUMOR
O LARGE TUMOR
Figure 7-1, Pulmonary tumor incidence in female rats, 1965-1967.
Source: Reeves and Deitch (1969).
-------
Schepers (1964) found that among 20 female rhesus monkeys exposed to
inhalation of beryllium sulfate (BeSO.), beryllium phosphate (BeHPO.), or
beryllium fluoride (BeF,), in concentrations ranging from 0.035 to 8.3 mg
3
beryllium/m , one animal had a small pulmonary neoplasm that appeared to be an
alveolar carcinoma. The animal was in the beryllium phosphate (1.1 mg
3
beryllium/m ) exposure group, and the tumor, which had a maximum diameter of
3 mm, was found on the 82nd day following commencement of exposure. Its
connection with the beryllium exposure was judged to be uncertain.
Vorwald (1968) reported the outcome of a 3-year chamber study on rhesus
monkeys inhaling an aerosol of beryllium sulfate, with intermittent exposure
averaging about 15 hours/week, at a mean atmospheric concentration of 38.8 ug
3
beryl!ium/m . Eight of 11 surviving monkeys had pulmonary tumors, with adeno-
matous patterns predominating among areas with epidermoid characteristics.
Extensive metastases to the mediastinal lymph nodes, and in some animals to
the bones, liver, and adrenals, were seen. No control animals were kept in
this experiment.
Dutra et al. (1951) exposed 5, 6, and 8 rabbits to beryllium oxide aerosol
3
(degree of firing unidentified) at 1, 6, and 30 mg beryllium/m , respectively,
on a 25-hours/week schedule for 9-13 months. One rabbit in the 6 mg beryllium/
3
m group developed osteosarcoma of the pubic bone, with extension into the
contiguous musculature. Scattered tumors, which were judged to be metastases
of the osteogenic sarcoma, were seen in the lungs and spleen. The lungs also
exhibited extensive emphysema, interstitial fibrosis, and lymphocytic infiltra-
tion. Rabbits in the other groups remained free of malignancies.
7.1.2 Intratracheal Injection Studies
Intratracheal administration of beryllium compounds was practiced as a
shortcut for inhalation experiments by Vorwald (1953), Van Cleave and Kaylor
(1955), Spencer et al. (1965), Kuznetsov et al. (1974), Ishinishi et al. (1980),
and Groth et al. (1980). The fate and effects of these deposits are not neces-
sarily the same as that of identical compounds deposited by inhalation. The
intratracheal injection produces an unnatural deposition pattern in the lung
and also allows the pulmonary entry of larger particles, those that normally
would be filtered out in the upper respiratory tract. Dusts of a certain
compound, therefore, frequently show longer pulmonary half-times after intra-
tracheal injection than after inhalation.
7-7
-------
Vorwald (1953) reported one lung tumor after intratracheal injection of
338 ng beryllium (as beryllium oxide) and one "sarcoma" (site unidentified)
after intratracheal injection of 33.8 |jg beryllium (as beryllium sulfate); the
induction of lung cancer with intrathoracic metastases in rhesus monkeys
following intrabronchial injection and/or bronchomural implantation of "pure"
beryllium oxide (firing temperature unknown) was also mentioned in a review,
without reference to any original publication (Vorwald et al., 1966).
Groth et al. (1980) injected dusts of beryllium metal, passivated beryll-
ium metal (with < 1 percent chromium) and various beryllium alloys, as well as
beryllium hydroxide, intratracheally into rats. Lung tumors were observed
after injection of beryllium metal, passivated beryllium metal, and a beryllium-
aluminum alloy (containing 62 percent beryllium), but not after injection of
other beryllium alloys in which the beryllium concentration was < 4 percent;
injection of beryllium hydroxide into 25 rats yielded 13 cases of neoplasia,
of which 6 were judged to be adenomas and 7 were adenocarcinomas (Table 7-3).
The rest of the animals had various degrees of metaplasia, which was regarded
as precancerous lesions. Several of the tumors were successfully transplanted.
The most detailed studies with intratracheal injections of beryllium were
reported by Spencer et al. (1965, 1972). High-fired (1600°C), medium-fired
(1100°C), and low-fired (500°C) specimens of beryllium oxide were injected
into rats; the incidence of pulmonary adenocarcinomas was 3/28, 3/19, and
23/45 in the three groups, respectively, corresponding to 11, 16, and 51 per-
cent.
Ishinishi et al. (1980) injected 30 rats with beryllium oxide (calcined
at 900°C) by the intratracheal route, in 15 weekly doses of 1 mg each. Of 29
animals examined 1.5 years later, 7 (24 percent) had lung tumors, i.e., one
squamous cell carcinoma, one adenocarcinoma, four adenomas, and one malignant
lymphoma. Of the four adenomas, three had "strong histological architectures
[of] suspected malignancy" (Tables 7-4 and 7-5). The malignant lymphoma was
found not only in the lung but also in the hilar lymph nodes and in the abdomi-
nal cavity, with the primary site remaining undetermined. Six extrapulmonary
lymphosarcomas, fibrosarcomas, or other tumors were found in further injected
animals but in only one of 16 control animals. The incidence of clearly
malignant primary pulmonary tumors in this experiment was 2/29, or 7 percent.
7-8
-------
TABLE 7-3. BERYLLIUM ALLOYS—LUNG NEOPLASMS
Compounds
Be metal
Be metal
Passivated Be metal
Passivated Be metal
BeAl alloy
BeAl alloy
4% BeCu alloy
4% BeCu alloy
2.2% BeNi alloy
2.2% BeNi alloy
2.4% BeCuCo alloy
2.4% BeCuCo alloy
Sal ine
Dose of
compound
(mg)
2.5
0.5
2.5
0.5
2.5
0.5
2.5
0.5
2.5
0.5
2.5
0.5
"•
Dose of
Be
(mg)
2.5
0.5
2.5
0.5
1.55
0.3
0.1
0.02
0.056
0.011
0.06
0.012
*~
Total
no. rats
autopsied
16
21
26
20
24
21
28
24
28
27
33
30
39
Autopsy intervals and lung
neoplasm incidences (months)
1
0/5b
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
2-7
-
0/3
0/2
0/1
0/3
-
0/1
0/2
0/1
0/2
0/3
0/2
0/3
8-10
-
0/5
1/5
0/3
2/5
0/1
0/5
-
0/5
-
0/5
-
0/5
11-13
3/5
0/5
4/10
-
0/5
0/6
0/6
0/4
0/5
0/5
0/5
0/5
0/5
16-19
6/6
2/3
4/4
7/11
2/6
1/9
0/11
0/13
0/12
0/15
0/15
0/18
0/21
a
P value
<0.0001
0.011
<0.0001
0.0001
0.043
0.30
P value (Fisher's one-tailed test) when the lung neoplasm incidence in exposed groups is compared with the lung
neoplasm incidence in the saline control group at the autopsy period of 16-19 months. Because of multiple
comparisons with the control group, the individual P value must be 0.008 or less to be significant.
Number of rats with a lung neoplasm divided by total number of rats autopsied at the specified interval.
Source: Groth et al. (1980)
-------
TABLE 7-4. LUNG TUMOR INCIDENCE IN RATS AMONG BeO, As203 AND CONTROL GROUPS
Group
BeO (1 mg)*
As203 (1 mg)*
Control
Sex
M
M
M
Number of rats
surviving after
15 instillations
30/30
19/30
16
Average
545
546
398
Range
99-791
98-820
1-617
Mai ignant
tumor
2+(l)A
1
0
Benign
tumor
4
0
0
*Amount of one instillation Be or As.
Unknown which is primary tumor or metastasis.
Source: Ishinishi et al. (1980)
TABLE 7-5. HISTOLOGICAL CLASSIFICATION OF LUNG TUMORS AND OTHER PATHOLOGICAL CHANGES
i
i—1
o
Group
BeO (1 mg as Be)
As203 (a mg as As)
Control
Sex
M
M
M
No. of
rats
29*
18*
16
Malignant
Squamous
cell
carcinoma
la
1
0
tumors (A)
Adeno-
carcinoma
lb
0
0
Benign tumors (B)
Mai ignant
lymphoma
d)C
0
0
Ade-
noma
4(3)A
0
0
All
tumors
(A + B)
[tumor
incidence
rats]
21.4%
5.6%
0
Squamous
cell
meta-
plasia
2
5
1
Osseous
metaplasia
1
2
0
Other
site
tumors
except
the lung
tumor
1
Coexistence of squamous cell carcinoma and adenocarcinoma.
Coexistence of adenocarcinoma and adenoma.
Malignant lymphoma in the left lobule of the lung, the lymphatic nodules in
the pulmonary hilus, and in the abdominal cavity.
Lymphosarcoma or fibrosarcomas (except one).
eMesothelioma in peritoneum, liver and mesentery.
*0ne rat was not histopathologically observed because of cannibalism.
Three of four adenomas have strong histological architectures of suspected malignancy.
Source: Ishinishi et al. (1980)
-------
7.1.3 Intravenous Injection Studies
In 1946, Gardner and Heslington, in a search to find the cause of an
"unusual incidence of pulmonary sarcoid" in the fluorescent light tube industry,
injected zinc beryllium silicate (ZnBeSiO,) into rabbits and obtained osteosar-
«5
coma of the long bones in all seven animals which survived the treatment for 7
months or more. Because this was the first instance of experimental carcino-
genesis by an inorganic substance, it evoked great interest. Beryllium was
clearly implicated as the causative agent because zinc oxide, zinc silicate,
or silicic acid did not cause osteosarcoma in a second set of trials, whereas
beryllium oxide (firing temperature unknown) did. Guinea pigs and rats, when
similarly treated with both zinc beryllium silicate and beryllium oxide,
failed to respond. The dose of beryllium within the two compounds injected
(beryllium oxide and zinc beryllium silicate) was 360 and 60 mg, respectively,
in 20 divided doses during a 6-week period.
This basic experiment was repeated many times by several investigators
(Tables 7-6 and 7-7). Cloudman et al. (1949) produced osteosarcoma in four
out of five rabbits receiving a total dose of 17 mg beryllium (as zinc beryl-
lium silicate); mice were also injected, with production of "some" tumors
(count or incidence percentages not stated). In this experiment, "substanti-
ally 100 percent beryllium oxide by spectrographic standards" (degree of
firing not stated, total dose 1.54-390 mg beryllium) produced no tumors. Nash
(1950) produced five cases of osteosarcoma with zinc beryllium silicate phosphor
among 28 injected rabbits, with about 200 mg zinc beryllium silicate (12 mg
beryllium) appearing to be the minimum effective dose. Dutra and Largent
(1950) produced osteosarcoma in rabbits with both zinc beryllium silicate
(2/3) and beryllium oxide (6/6), and reported a successful transplant in the
anterior chamber of the eye of a guinea pig. Barnes et al. (1950) produced
six cases of osteosarcoma among 17 rabbits injected with zinc beryllium sili-
cate and one case of osteosarcoma among 11 rabbits injected with beryllium
silicate. The tumors were multicentric in origin; blood-born metastases were
stated to be common. Hoagland et al. (1950) injected rabbits with 2 samples
of zinc beryllium silicate phosphor, containing 2.3 and 14 percent beryllium
oxide, and produced an osteosarcoma incidence of 3/6 and 3/4, respectively.
With uncompounded BeO, the incidence was 1/8; beryllium phosphate produced no
tumors. The osteosarcomas appeared to be highly invasive, but could not be
transplanted.
7-11
-------
TABLE 7-6. OSTEOGENIC SARCOMAS IN RABBITS'
Compound
ZnBeSi03
BeO
ZnBeSi03
ZnBeSi03
ZnMnBeSi03
ZnMnBeSi03
BeO
Be metal
ZnBeSi03
BeSi03
ZnBeSi03
BeO
ZnBeSi03
ZnBeSi03
BeO
Dose of
compound
(g)
i
i
UN
UN
0.45-0.85
0.2
UN
0.04
1-2.1
1-1.2
UN
UN
1
1
1
Be phosphate 0. 103
BeO
BeO
ZnBeSi03
BeO
Totals for
0.22-0.4
0.42-0.6
0.02
Inhalation
6 mg Be/M3
Dose of
beryl 1 ium
(mg)
UN
360
17
0.264
3.7-7.0
10-12.6
360
40
7.2-15
UN
64-90
360-700
12
12
360
UN
79-144
151-216
0.144
ZnBeSi03 + ZnMnBeSi03
Route
of
injection
i v
iv
iv
iv(M)
i v
i v
iv
iv
i v
iv
i v
i v
i v
iv
i v
i v
IMD
IMD
IMD
i v
No. of
animal s
with tumors
7
1
4
1
3
3
1
2
6
1
2
6
5
10
3
1
7
11
4
1
40
Incidence
of
tumors
7/7 (100%)
UN
4/5 (80%)
UN
> 3/6 (50%)
> 3/4 (75%)
> 1/9 (11%)
2/5 (40%)
6/13 (46%)
1/8 (13%)
2/3 (67%)
6/6 (100%)
5/10 (50%)
10/13 (77%)
UN
UN
7/9 (78%)
11/11 (100%)
4/12 (33%)
£ 1/6 (£17%)
40/61 (66%)
Incidence
of
metastases
3/7 (43%)
UN
3/4 (75%)
UN
5/7 (71%)
UN
4/6 (67%)
None
2/2 (100%)
6/6 (100%)
>2/5 ( 40%)
UN
2/3 (66%)
UN
UN
UN
3/4 (75%)
1/1 (100%)
£ 18/30 (60%)
Reference
Gardner and Heslington, 1946
Cloudman et al . , 1949
Hoagland et al . , 1950
Barnes et al. , 1950
Barnes et al . , 1950
Dutra and Largent, 1950
Janes et al. , 1954
Kelly et al . , 1961
Komi tows ki, 1967
Vorwald, 1950
Yamaguchi, 1963
Tapp, 1969
Dutra et al . , 1951
UN = unknown; IMD = intramedullary; ZnBeSi03 = zinc beryllium silicate; (M) = mouse; ZnMnBeSi03 = zinc manganese
beryllium silicate; BeO = beryllium oxide.
Source: Groth (1980)
-------
TABLE 7-7. OSTEOSARCOMA FROM BERYLLIUM
OJ
Author
GARDNER
CLOUDMAN
BARNES
HOAGLAND
NASH
DUTRA
JANES
KELLY
HIGGINS
Year
1946
1949
1950
1950
1950
195O
1951
1954
1956
1961
1964
Species
Rabbits
Guinea pigs
Rals
Rabbits
Mice
Rabbits
Rabbits
Rabbits
Rabbits
Rabbits
Splenectomlied
rabbits
Rabbits
Rabbits
Compound
Zn Be silicate
BeO
Zn Be silicate
BeO
Zn Be silicate
BeO
Zn Be silicate
BeO
Zn Be silicate
BeO
Zn Be silicate
BeO
Zn Be silicate
(BeO = 2.3%)
Zn Be silicate
(BeO = 14%)
Be phosphate
BeO
Zn Be silicate
BeO
Zn Be silicate
Mode of
Administration
i v. in 20 doses
l.v. In 20-22 doses
i.v. In 6- 10 doses
i.v. In 1 -30 doses
l.v. "repeated"
i.v. in 17- 25 doses
l.v. in 20- 26 doses
inhalation
25 hrs/wk
9-10 months
l.v. In 20 doses
Total
Dose
(mo, Be)
60
360
60
360
60
360
17
140
026
0.55
7.2
16
180
3-7
10-12
130?
360
12*
64-90
360-700
r
6*
30'
12
12
12
3300
Incidence
of
Osteosarcoma
7 in 7
tin?
0
0
0
0
4in5
0
"some"
0
4 in 14
2in3
1in11
3in6
3»n4
OinS
linB
5 in 28
2in3
6in6
OinS
1in6
OinS
Bin 10
7 in 7
10 In 14
"many*
* atmospheric concentration in mg Be/m'
Source: Reeves (1978)
-------
Araki et al. (1964) injected 35 rabbits with zinc beryllium manganese
silicate (ZnEJeMnSioO, zinc beryllium silicate (ZnBeSiCL), or beryllium phos-
phate (BeHPCK). The incidence of osteosarcoma was 6/24, 2/7, and 2/4 in the
three groups, respectively; there were no tumors among three rabbits injected
with beryllium oxide (firing temperature unstated) or among two uninjected
controls. There was also a primary thyroid tumor in the group injected with
zinc beryllium manganese silicate. Liver cirrhosis and splenic fibrosis were
also observed; transplant experiments were all negative.
Several experiments were reported from the Mayo Foundation (Janes et al.,
1954, 1956; Kelly et al., 1961) which also confirmed the carcinogenic effects
of intravenous beryllium on bone. Out of a combined total of 31 rabbits
receiving zinc beryllium silicate in a total dose of 12 mg beryllium, 22
developed osteosarcomas. New bone formation was observed in the medullary
cavities of the long bones before the malignant changes became apparent. Of
particular interest were observations of atrophy of the spleen in those animals
in which bone tumors developed, while in the injected rabbits that did not
develop the bone tumors, the spleen seemed to be normal. Following splenectomy,
the incidence of bone tumor or new bone formation in the medullary cavity was
100 percent, whereas the incidence of these developments in non-splenectomized
rabbits after identical injection was only 50 percent. The results suggest that
a well-functioning spleen may serve as protection against beryllium carcino-
genesis in the rabbit. Tibial chondrosarcomas were also produced, and success-
ful transplants to the anterior chambers of the eyes of rabbits were performed
(Higgins et al. , 1964).
7.1.4 Intramedullary Injection Studies
Beryllium oxide or zinc beryllium silicate was directly introduced into
the medullary cavity of bones of rabbits by Yamaguchi (1963), Tapp (1969), and
Fodor (1977). Osteosarcoma, chondrosarcoma, and presarcomatous changes (irre-
gular bone formation) were observed; 20-30 injections (20 mg beryllium oxide
per injection) gave the highest frequency of tumor formation. The tumors
developed directly from the medullary bone, and were sometimes preceded by
fibrosis. They metastasized to liver, kidney, lymph nodes, and in especially
high frequency, to the lung.
7-14
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7.1.5 Intracutaneous Injection Studies
No neoplasms were produced by intracutaneous injection of beryllium
sulfate, or by introduction of insoluble beryllium compounds (beryllium oxide,
beryllium phosphate, beryllium-containing fluorescent phosphors) into acciden-
tal cuts of the skin. The lesions thus produced were cutaneous granulomas,
or, in the case of extensive injury, necrotizing granulomatous ulcerations
(Van Ordstrand et al., 1945; Reeves and Krivanek, 1974).
Intracutaneous administration of beryllium sulfate in doses of 5 ug
beryllium was practiced in the immunotoxicologic experiments of Reeves et al.
(1971, 1972); there was no evidence that measurable amounts of beryllium left
the sites of administration.
7.1.6 The Percutaneous Route of Exposure
No neoplasms were ever observed following the percutaneous route of
exposure in any species. Eczematous contact dermatitis in humans following
work with soluble compounds of beryllium was first described by Van Ordstrand
et al. (1945), and Curtis (1951) studied the allergic etiology of these reac-
tions and developed a patch test. In 1955, Sneddon reported that a patient
with a patch test positive to beryllium developed a sarcoid-like granuloma at
the test site. Granulomatous ulcerations followed if insoluble beryllium
compounds became imbedded in the skin. Dutra et al. (1951) could produce
experimental beryllium granulomas in the skin of pigs which resembled the
human lesion. There is no record of any of these lesions ever undergoing
malignant degeneration.
In view of the virtual impenetrability of the intact skin to beryllium
(section 4.1.3), the fact that no neoplasms were observed to occur by the
percutaneous route of exposure could be explained by the lack of absorption
through intact skin.
7.1.7 Dietary Route of Exposure
No neoplasms have ever been known to be observed following beryllium
exposure by the dietary route in any species. Guyatt et al. (1933), Jacobson
(1933), and Kay and Skill (1934) produced rickets in young rats fed beryllium
carbonate at 0.1-0.5 percent dietary level. This result is attributable to
intestinal precipitation of beryllium phosphate and consequent phosphorus
deprivation. Sols and Dierssen (1951) observed a decrease in the intestinal
7-15
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absorption of glucose at similar intake concentrations, attributable to inhi-
bition of alkaline phosphatase (Du Bois et al., 1949). At intake levels of
5-500 ppm in diet, no toxic effects of any kind were found (Reeves, 1965;
Schroeder and Mitchener, 1975; Morgareidge et al., 1977).
If insoluble beryllium dusts (beryllium, beryllium alloys, beryllium
oxide, beryllium phosphate, beryllium ores) are ingested, the bulk of these
substances will pass through the gastrointestinal tract unabsorbed. Depending
on the size of the particles, and, in the case of beryllium oxide, on the firing
temperature, a minor proportion of these dusts could become dissolved in
gastric juices, and traces of the resultant beryllium chloride could be absorbed
from the stomach. Upon entry into the intestine, any dissolved beryllium would
become precipitated again, mainly as beryllium phosphate (Reeves, 1965).
Soluble beryllium salts [beryllium fluoride (BeF,,), beryllium chloride
(BeCl2), beryllium sulfate (BeS04), and beryllium nitrate (Be[N03]2)] are
available for absorption in the stomach, to the extent that there is alimentary
absorption from the stomach, which in most mammalian species is recognized as
very minor. At levels of intake of 0.6-6.6 ug beryllium/day in the drinking
water of rats, 80+ percent of the intake passed the gastrointestinal tract
unabsorbed. Upon entering the alkaline milieu of the intestine, the beryllium
became precipitated and was excreted in the feces (Reeves, 1965; Furchner
et al., 1972; Schroeder and Mitchener, 1975). There is some evidence that in-
creasing the intake concentration does not increase the amount absorbed from
the intestine, because the latter is governed by the solubility of the intes-
tinal precipitates rather than by the total beryllium levels present.
7.1.8 Tumor Type, Species Specificity, Carcinogenic Forms, and Dose-Response
7.1.8.1 Tumor Type and Proofs of Ma1ignancy--The pulmonary neoplasms found in
rats after beryllium exposure were classified as adenocarcinomas, showing a
predominantly alveolar pattern. Reeves et al. (1967) distinguished four
histological variants, including focal columnar, focal squamous, focal vacuolar,
and focal mucigenous. Schepers et al. (1957) distinguished several more,
including some adenomas not judged to be malignant. Wagner et al. (1969) and
Groth et al. (1980) found that about half of the tumors they produced with
beryllium were benign adenomas. The diagnosis of pathological lesions is
complicated, and requires judgment and special experience. The histological
differentiation between adenomas and adenocarcinomas is not always well defined,
7-16
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and may also have species-related peculiarities, so that different conclusions
on the same specimen may sometimes be reached by pathologists, and especially
by those who have been trained in human medicine rather than veterinary medicine.
It is also noteworthy that neoplasia in the lungs of rats was invariably
associated with the purulent lesions of chronic murine pneumonia, which itself
was exacerbated by inhalation of the acidic beryllium sulfate aerosol.
Metastases as well as successful transplants were claimed by Schepers et
al. (1957); neither were explicitly observed or successfully accomplished in
the rat experiments of Vorwald, although this was reported with ambiguity when
these studies were published (Vorwald et al., 1966; see also Lesser, 1977). In
the monkey experiments of Vorwald (1968), which lacked controls, extensive
metastases to the mediastinal lymph nodes and sometimes to the bones, liver,
and adrenals were reported. Groth et al. (1980) accomplished successful
transplants in experiments with intratracheal administration of beryllium
metal and beryllium alloy, but metastasis to the mediastinal lymph node was
observed in only one animal.
The bone neoplasms produced with intravenous or intramedullary administra-
tion of beryllium to rabbits are surrounded with considerably less uncertainty.
The malignant osteosarcoma or chondrosarcoma character of these neoplasms has
not been challenged, and metastases to all parts of the body were observed—but
it is noteworthy that the transplant experience in these studies was non-
uniform. Successful transplants to the anterior chamber of the eye were
reported by Dutra and Largent (1950) and Higgins et al. (1964), whereas failure
with transplants was expressly admitted by Hoagland et al. (1950) and Araki et
al. (1954). It is possible that the degree of malignancy of the bone tumors
depended somewhat on the type of compound used in the injection.
7.1.8.2 Species Specificity and Immunobio1ogy--Pu1monary tumors were produced
after inhalation exposure and sometimes after intratracheal injection in rats
(Vorwald, 1953; Vorwald et al., 1955; Schepers et al. , 1957; Schepers, 1961;
Vorwald et al., 1966; Reeves et al., 19$7; Reeves and Deitch 1969; Spencer et
al., 1968 and 1972; Wagner et al., 1969; Groth et al., 1980; Ishinishi et al.,
1980) and perhaps in monkeys (Schepers, 1964; Vorwald et al., 1966; Vorwald,
1968; but see also Wagner et al., 1969 for negative evidence). No pulmonary
tumors were produced in rabbits (Vorwald, 1950), hamsters (Wagner et al.,
1969), and guinea pigs (Vorwald, 1950; Schepers, 1961; Reeves et al., 1972).
7-17
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Bone tumors were produced by intravenous or intramedullary injection in
rabbits (Gardner and Heslington, 1946; Dutra and Largent, 1950; Barnes et al.,
1950; Hoagland et al. , 1950; Araki et al., 1954; Janes et al., 1954 and 1956;
Kelly et al. , 1961; Yamaguchi, 1963; Higgins et al. , 1964; Tapp, 1969; and
Fodor, 1977). The one nondetailed report claiming osteosarcoma in mice (Cloudman
et al., 1949) needs confirmation, as does the report of osteosarcoma in rabbits
after inhalation exposure (Dutra et al., 1951). Bone tumors were never observed
in rats and guinea pigs.
It would appear from these data that pulmonary tumors can be obtained
with beryllium in rats and perhaps in monkeys, but not in rabbits, hamsters,
and guinea pigs; and that bone tumors can be obtained with beryllium in rabbits
and perhaps in mice, but not in rats and guinea pigs. The negative evidence
with guinea pigs is particularly strong and involves both intravenous injection
(Gardner and Heslington, 1946; Vorwald, 1950) and inhalation (Schepers, 1961;
Reeves et al., 1972) at levels that were definitely carcinogenic in rabbits
and rats, respectively.
This apparent species specificity, which might operate with other types
of carcinogenesis as well (guinea pigs are generally regarded as poor models
for cancer induction), has remained thus far quite unexplored. It is certainly
noteworthy that guinea pigs develop cutaneous hypersensitivity to beryllium,
whereas rats do not (Reeves, 1978). In rabbits, the spleen has been found to
be involved in the neoplastic response to intravenous beryllium. Gardner and
Heslington (1946) observed prompt splenic atrophy in beryllium-injected rabbits;
Janes et al. (1954) found that the splenic atrophy afflicted only those animals
that developed the osteosarcomas, whereas the nonresponding animals had a
normal-looking spleen. In a later work, Janes et al. (1956) could increase
the yield of osteosarcomas in beryllium-injected rabbits twice by performing
splenectomy. These studies allow the working hypothesis that some form of
cellular immunity, with the immunocompetent cells arising from the spleen, may
be a factor in determining whether the response to beryllium will be neoplastic
or not, and that various species, or perhaps various members of one species,
have resistance to beryllium cancer according to their immunocompetence.
7.1.8.3 Carcinogenic Forms and Dose-Response Relationships—There is insuffi-
cient evidence to implicate any specific chemical form of beryllium as the
exclusive carcinogenic entity. Ionic beryllium changes to beryllium hydroxide
upon inhalation, and both forms, upon inhalation or intratracheal injection,
7-18
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respectively, have caused pulmonary tumors in rats (Vorwald, 1953; Schepers et
al., 1957; Reeves et al. , 1967; Groth et al., 1980). There is reason to
believe that beryllium hydroxide particles can change to beryllium oxide upon
aging (Reeves, in press). Beryllium oxide, when directly introduced into the
lungs of rats, showed a remarkable pattern of carcinogenicity, clearly indica-
ting that firing temperature had a definite influence on the tumor yield and
that only "low-fired" (500°C) beryllium oxide was highly carcinogenic (Spencer
et al., 1968, 1972). Sanders et al. (1978) observed only one case of lung
tumor among 184 rats exposed to "medium-fired" (1000°C) beryllium oxide.
Frequently, no tumors were obtained with beryllium oxide; however, in early
studies, the type of beryllium oxide to which the animals were exposed was not
generally identified (Cloudman, 1949; Dutra and Largent, 1950; Hoagland et
al., 1950; Araki et al., 1954; Vorwald et al., 1966).
Experiments aiming at the establishment of a dose-response relationship
with intravenous beryllium are limited. Nash (1950) suggested 12 mg beryllium/
rabbit as the minimum effective total dose to produce osteosarcomas; in the
experiments of Hoagland, incidence of osteosarcomas increased from 50 to
75 percent as beryllium oxide content of a fluorescent phosphor was increased
from 2.3 percent to 14 percent. Barnes et al. (1950) could increase the
incidence of rabbit osteosarcomas from 4/14 (29 percent) to 2/3 (67 percent)
by doubling the dose of intravenous zinc beryllium silicate from 7.5 to 15 mg.
However, in the inhalation experiment of Dutra et al. (1951) and in the intra-
medullary experiments of Yamaguchi (1963), there was no clear-cut relation
between dose and tumor yield.
Vorwald et al. (1966) cited results of their own unpublished studies,
according to which "almost 100 percent of a large number of rats" developed
lung cancer after 18 months of exposure to 42 or 21 pg beryllium (as beryllium
O *)
sulfate)/m ; after exposure to 2.8 ug beryllium (as beryllium sulfate)/m , the
incidence of lung cancer was 13/21 (62 percent). These figures came under
considerable scrutiny during the beryllium hearings at the Occupational Safety
and Health Administration (Lesser, 1977). It was pointed out that these
experiments were poorly controlled and that at least the data of the exposure
o
intended to be 2.8 pg beryllium/m deserved no confidence. Wagner et al.
(1969) could obtain pulmonary tumors in rats with beryl ore (beryllium content
4.14 percent) but not with bertrandite ore (beryllium content 1.4 percent).
Similarly, Groth et al. (1980) obtained pulmonary tumors with beryllium metal,
7-19
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beryllium hydroxide, and a beryllium-aluminum alloy, with beryllium content
ranging from 62 to 100 percent; whereas with other alloys, ranging in beryllium
content from 2.2 to 40 percent, they obtained no tumors. Thus, the evidence
points to the existence of a definable dose-response relationship in experi-
mental beryllium carcinogenesis.
Reeves (1978) examined this relationship by the probit method. For the
induction of osteosarcoma in rabbits following intravenous injection of zinc
beryllium silicate, the median effective total dose per animal was 11.0 mg
beryllium; the curve intersected the 1 percent incidence level at 3.8 mg, the
0.1 percent incidence level at 2.7 mg, and the 0.01 percent incidence level at
2.0 mg. For the induction of pulmonary carcinoma in rats after inhalation of
beryllium sulfate (35 hours/week chamber exposure lasting 3 months or more),
the median effective concentration was 18.0 ug beryllium/m ; the curve inter-
3
sected the 1 percent incidence level at 12.0 ug/m , the 0.1 percent incidence
3 3
level at 10.5 ug/m , and the 0.01 percent incidence level at 9.0 ug/m .
Obviously, these estimates are subject to considerable uncertainty.
7.1.9 Summary of Animal Studies
This section has presented a discussion of animal experiments concerning
the carcinogenicity of beryllium, as summarized by Reeves (1978), Groth (1980),
and Kuschner (1981). These studies are listed in Table 7-8.
Experimental beryllium carcinogenesis was successfully accomplished by
intravenous or intramedullary injection of rabbits and, perhaps, of mice; and
by inhalation exposure or intratracheal injection of rats and, perhaps, of
monkeys and rabbits. Not susceptible to beryllium carcinogenesis are guinea
pigs and, perhaps, hamsters. This species specificity appears to be connected
with immunocompetence.
In rabbits, osteosarcomas and chondrosarcomas were obtained. The tumors
were highly invasive, metastasized readily, but gave variable transplant
experience. They were judged to be histologically similar to corresponding
human tumors. In rats, pulmonary adenomas and/or adenocarcinomas of question-
able malignancy were obtained. The tumors were less invasive, and both the
metastasis and transplant experiences were variable. They appeared to be
histologically associated with the purulent lesions of chronic murine pneumonia.
There is some evidence that the carcinogenicity of beryllium oxides is
inversely related to their firing temperature, with only the "low-fired" (500°C)
7-20
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TABLE 7-8. CARCINOGENICITY OF BERYLLIUM COMPOUNDS
Year
1946
1949
1949
1950
1950
1950
i
1X1 1951
)_«i -LJ+Jl.
1953
1954
1954
1957
1961
1964
1964
Species
rabbit
mouse
rabbit
rabbit
rabbit
rabbit
rabbit
rat
rabbit
rabbit
rat
rabbit
rabbit
rabbit
Compound
zinc beryllium silicate
zinc beryllium silicate
zinc beryllium silicate
zinc beryllium silicate
and beryl 1 ium metal
zinc beryllium silicate
beryllium oxide and
zinc beryllium silicate
beryllium oxide
beryllium sulfate
tetrahydrate
beryllium phosphate
beryllium oxide
zinc beryllium silicate
beryllium sulfate
tetrahydrate
zinc beryllium silicate
zinc beryllium silicate
zinc beryllium silicate
Route of Administration
intravenous
intravenous
intravenous
intravenous
intravenous
intravenous
inhalation
inhalation
intravenous
intravenous
inhalation
intravenous
intravenous
intravenous
Tumor
osteosarcoma
"mal ignant bone
tumors"
osteosarcoma
osteosarcoma
osteosarcoma
osteosarcoma
osteosarcoma
lung cancer
(adeno and
squamous)
osteosarcoma
osteosarcoma
lung cancer
(adeno and
squamous)
osteosarcoma
chondrosarcoma
osteosarcoma
Reference
Gardner
Cloudman
Cloudman
Barnes, Barnes,
Sissons
Hoagland
Dutra
Dutra
Vorwald
Araki
Janes
Schepers
Kelly
Higgins
Peterson
(continued on the following page)
-------
TABLE 7-8. (continued)
Year
1965
1966
1967
1968
1969
1969
1969
1969
Species
rat
monkey
monkey
rat
rabbit
rat
hamster
monkey
rabbit
Compound
beryllium sulfate
tetrahydrate
beryl 1 ium oxide
beryllium sulfate
tetrahydrate
beryllium sulfate
tetrahydrate
beryllium oxide
beryl ore
bertrandite ore
beryl ore
bertrandite ore
beryl ore
bertrandite ore
zinc beryllium silicate
beryllium silicate
beryllium oxide
Route of Administration
ingest ion
intratracheal
insti 1 lation
inhalation
inhalation
intravenous
inhalation
inhalation
inhalation
subperiosteal
injection
Tumor
no greater than
controls
pulmonary cancer
(anaplastic)
pulmonary cancer
1 ung-cancer
(al veolar-adeno Ca)
osteosarcoma
lung cancer (adeno)
no tumors
none
none
none
none
osteosarcoma
osteosarcoma
osteosarcoma
Reference
Schroeder
Vorwald
Vorwald
Reeves
Komi tows ki
Wagner
Wagner
Wagner
Tapp
1972
1975
rat
rat
beryl ore
beryl 1ium oxide
beryllium hydroxide
beryl 1ium metal
beryllium fluoride
beryl!ium chloride
intratracheal
inhalation
pulmonary tumors Groth
pulmonary tumors
pulmonary tumors
pulmonary tumors
lung cancer Lituinov
(adeno and squamous)
(continued on the following page)
-------
TABLE 7-8. (continued)
ro
CO
Year
1975
1977
1978
1979
1980
Species
rabbit
rat
rat
rat
rat
Compound
zinc beryllium silicate
beryllium sulfate
tetrahydrate
beryllium oxide
beryl 1 ium metal
beryllium alloy
passivated beryllium metal
beryllium hydroxide
beryl 1 ium oxide
Route of Administration
intramedullary
ingestion
inhalation
intratracheal
instil lation
intratracheal
instillation
Tumor
osteosarcoma
7
no greater than
controls
single lung cancer
(adeno)
lung cancer (adeno
and squamous)
it
ii
lung cancer
(squamous, adeno,
lympho)
Reference
Mazabraud
Morgareidge
Sanders
Groth
Ishinishi
Source: Adapted from Kuschner (1981)
-------
variety presenting a substantial hazard. Limited dose-response evidence indi-
cates about 2.0 mg beryllium (as beryllium oxide) as the minimum intravenous
dose for production of osteosarcomas in rabbits, and about 10 ug beryllium (as
3
beryllium sulfate)/m as the minimum atmospheric concentration for production
of adenocarcinomas in rats.
Although some studies involving beryllium clearly have limitations, the
totality of the data, using the criteria of the International Agency for
Research on Cancer (IARC), requires that beryllium be placed in the "sufficient
evidence" category of animal carcinogens.
7.2 EPIDEMIOLOGIC STUDIES
7.2.1 Bayliss et al. (1971)
The first in a series of government-sponsored studies of cancer in workers
exposed to beryllium was accomplished by Bayliss et al. (1971). This cohort
mortality study consisted originally of some 10,356 former and current employees
of the beryllium-processing industry (two companies in Ohio and Pennsylvania)
of which 2,153 had to be excluded because insufficient information was available
with regard to these workers. Records consisted entirely of lists of names
only with approximate years of employment of individuals who were presumably
employed at the Brush Beryllium Company prior to 1942. No other information
was available on these workers from company employment records at the time
after an intensive search was completed. These lists were prepared by an
earlier Brush Beryllium Company physician who is now deceased. After the
additional removal of another 1,130 females, the study was left with 6,818
males. Of this number, 777 deaths occurred from January 1, 1942, to the end
of the cut-off date, December 31, 1967, compared to 842.4 expected deaths
based upon U.S. male death rates--a shortfall attributable to the "healthy
worker effect." Only a slightly elevated risk of lung cancer (International
Classification of Diseases [ICD] 160-164) was evident overall (36 observed
versus 34.06 expected). No significant risk of lung cancer was found to exist
in relation to length of employment, beginning date of employment, or kind of
employment (office versus production), nor were significant risks of other
forms of cancer evident from these data.
This study suffers from several deficiencies, not the least of which is
the fact that over 2,000 individuals had to be eliminated from the study
because data regarding birth date, race, and sex could not be obtained for
7-24
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them. The author indicated that this reduction in the size of the study
necessitated the elimination of some 251 deaths, and represented a loss of
over 20 percent of the cohort and 25 percent of the known deaths, a circum-
stance that had the potential for introducing considerable bias into the
results.
A second major problem with the study is the fact that it did not analyze
the data according to length of time since initial employment in the industry.
The lack of such an analysis meant that questions dealing with latency could
not be addressed in the study.
A third deficiency is that the populations of several different plants
were combined into one cohort for the study. As a result, the study failed to
consider the many potential differences of exposure levels in different plants.
Individuals were studied in groups according to their beginning dates and
durations of employment, despite the fact that their exposure histories may
have been totally dissimilar.
For the above-cited reasons, this study was deemed not useful for the
evaluation of cancer mortality in beryllium-exposed workers.
7.2.2 Bayliss and Lainhart (1972, unpublished)
In an attempt to remedy the deficiencies of their earlier study, Bayliss
and Lainhart (1972), in an unpublished study presented at the American Indus-
trial Hygiene Association meeting on May 18, 1972, narrowed the scope of study
to only one beryllium-processing company, which had seemingly complete employ-
ment records for two locations in Pennsylvania. This change effectively
reduced the size of the cohort to some 3,795 white males, while retaining the
same starting date and cut-off date as was used in the earlier study. In the
1972 version of the study, Bayliss et al. found that 601 members of the cohort
had died, as compared to 599.9 expected deaths based on period- and age-specific
U.S. white male death rates. Again, no significant excess of unusual mortality
from any cause was evident. For lung cancer (ICD 160-164) overall, 25 deaths
were observed versus 23.69 expected. Even when latency was considered, no
significant excess risk of lung cancer was apparent after a lapse of 15 years
from initial exposure, at which time 14 deaths were observed versus 13.28
expected. In addition, no significant risks were apparent in relation to
intensity of exposure, duration of exposure, or beginning date of employment.
The Bayliss and Lainhart (1972) study was criticized by Bayliss and Wagoner
(1977) in a third version of the study, which was submitted to the Occupational
7-25
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Safety and Health Administration (OSHA) as part of the beryllium standards
development process. In this criticism, the earlier paper was said to have
multiple limitations, among which were the following: 1) the study included
clerical and administrative workers who presumably had not been exposed to
beryllium; 2) the data were obtained from industrial representatives, which
precluded an independent assessment of plant employment files to ensure that
all potentially exposed workers were included; and 3) the study did not assess
latency 20 or more years after initial employment, although it did examine
mortality after a 15-year lapse.
7.2.3 Bayliss and Wagoner (1977, unpublished)
This third version of the Bayliss et al. study was reduced in size to a
cohort mortality study of workers employed at only one of the original company's
plants. The cohort studied was composed of 3,070 white males, who were followed
until January 1, 1976. Vital status was unknown for only 80 members of the
cohort (3 percent), and these individuals were considered to be alive until
the end of the study's cut-off period. Altogether, 884 deaths were observed,
as compared to 829.41 expected deaths based on period- and age-specific U.S.
white male death rates. A significant excess of lung cancer was noted (ICD
162-163), with 46 cases observed versus 33.33 expected (P < 0.05). A signifi-
cant excess of heart disease was also noted (399 observed versus 335.15 expec-
ted, P < 0.05), as was a significant excess of nonmalignant respiratory disease
(32 observed versus 19.02 expected, P < 0.01). Irrespective of duration of
employment, a significant excess was noted in bronchogenic cancer following a
lapse of 25 or more years since initial employment.
In the Bayliss and Wagoner (1977) study, the authors discussed for the
first time the impact of cigarette smoking as a possible confounding agent
contributing to the excess risk of lung cancer. An examination of the results
of a cross-sectional health examination survey conducted at the plant under
study by the U.S. Public Health Service (PHS) in 1968 revealed little differ-
ence in the cigarette-smoking patterns of the surveyed employees, as compared
to smoking patterns in the United States as a whole, determined from a health
interview survey conducted by the PHS from 1964 to 1965. An increase in the
percentage of heavier smokers was indicated in the 1968 survey, as compared
with national data (21.4 versus 15.3 percent). Because of the results just
cited, cigarette smoking was dismissed by the authors as the cause of the
7-26
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increased risk of bronchogenic cancer and other diseases in the cohort under
study. Dismissing the role of cigarette smoking as a contributing cause of
the excess risk of lung cancer may have been unwarranted for several reasons.
First, the smoking patterns of the 379 current employees surveyed in 1968 were
probably not the same as those of the entire cohort of 3,795, which included
current employees and past employees from as early as 1942. Second, the first
national reports of smoking as a cause of lung cancer were produced in 1964
and were accompanied by a great deal of media attention. By 1968, intense
media coverage dealing with the health consequences of smoking probably produced
a diminution of cigarette smoking among various subgroups of the population in
the 4-year interim period between surveys. Furthermore, while the 1968 survey
done at the plant did speak of current cigarette-smoking patterns, the issue
of prior cigarette smoking was not addressed, nor was the issue of pipe smoking
and cigar smoking. Additional criticisms of the Bayliss and Wagoner (1977)
study, as well as subsequent iterations of the same study, including the final
version (Wagoner et al., 1980), are discussed in the following review.
7.2.4 Wagoner et al. (1980)
Wagoner et al. (1980) reduced slightly the cohort of Bayliss and Wagoner
(1977) to a smaller cohort mortality study of 3,055 white males employed at
some time between January 1, 1942 and December 31, 1967, in the same beryllium-
processing facility. The results showed a significantly high risk of lung
cancer (47 observed versus 34.29 expected, P < 0.05) for those individuals
followed until December 31, 1975. This excess extended to members of the
cohort followed for more than 24 years since initial employment (20 observed
versus 10.79 expected, P < 0.01). When the analysis was confined to those
whose initial employment occurred prior to 1950, but who were followed for 15
years or more from date of initial employment, a significantly high risk of
lung cancer was apparent (24 observed versus 13.42 expected, P < 0.05). In
fact, no deaths from lung cancer were observed in anyone whose initial employ-
ment occurred after 1950 (0 observed versus 2.03 expected). The authors
concluded that this excessive risk of lung cancer "could not be related to an
effect of age, chance, self-selection, study group selection, exposure to
other agents in the study facility, or place of residence."
This study has received severe criticism from several sources: an internal
Center for Disease Control (CDC) Review Committee appointed to investigate
7-27
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defects in the study, several professional epidemiologists (MacMahon, 1977,
1978; Roth and Associates, 1983), and also one of the study's co-authors
(Bayliss, 1980). These researchers have criticized Wagoner et al. for inade-
quately discussing all qualifiers that might explain any of the significant
findings of their study.
The cohort studied in Wagoner et al. (1980) was composed of workers at
the facility who had been employed prior to December 31, 1967, based on the
facility's employment records and the results of a cross-sectional medical
survey done in 1968 at the plant. The cohort excluded employees who were not
directly engaged in the extraction, processing, or fabrication of beryllium,
or in on-site administrative, maintenance, or support activities. The numbers
of expected deaths used in the study were based on U.S. white male death rates
that had been generated by an analytic life table program designed by the
National Institute for Occupational Safety and Health (NIOSH). As a basis for
these calculations, the program used actual U.S. deaths recorded by cause,
age, race, sex, and year through 1967, together with census population data
from 1941 to 1967. These data were provided by the Bureau of the Census and
the National Center for Health Statistics. Unfortunately, at the time of this
study and subsequent studies on beryllium, cause of death information was not
available from these agencies on a year to year basis after 1967. As a result
the NIOSH life table program could not generate death rates during this period
without the application of certain assumptions. In order to estimate expected
deaths during the period from 1968 through 1975, death rates were assumed by
the authors to be unchanged from those generated by the NIOSH life table program
for the period from 1965 through 1967. The result was that for causes of death
with declining death rates, expected deaths were overestimated, with a resultant
underestimate of risk. Similarly, for those causes with increasing death rates
during the interval studied, expected deaths were underestimated, with a resul-
tant upward risk bias, as was the case with respect to all of the lung cancer
risk calculations made by the authors. After this problem had been corrected by
the inclusion of actual lung cancer mortality data for the period in question,
expected lung cancer deaths were recomputed prior to the publication of the
Wagoner et al. (1980) study by Bayliss (1980). The result was an increase from
34.29 to 38.2 expected lung cancer deaths, or an excess of 11 percent. This
correction in itself was enough to eliminate the statistical significance cal-
culated by Wagoner et al. in their overall lung cancer tabulation. With respect
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to latency, the risk of lung cancer was reduced to one of only borderline
significance in the cohort subgroup that was observed for 25 years or more
after initial employment. These corrections have been confirmed as correct by
Richard Monson (MacMahon, 1977, 1978), following a reanalysis of the NIOSH
data tapes in an independent Monson life table program at Harvard University.
Wagoner et al. found 875 deaths in their cohort. The vital status of 79
members of the cohort remained unknown as of December 31, 1975. The authors'
assumption was that these individuals would be counted as alive until the end
of the study, and that because of their added person-years, any finding of
increased cause-specific mortality would tend to be underestimated. Actually,
these 79 individuals represented only 2 percent of the total cohort, and any
additional person-years included from the time when they were last known to be
alive would have added little to the number of expected deaths. Furthermore,
given the intense scrutiny afforded this population in determining vital status
by both Wagoner and Mancuso in their own studies of the same workers, and con-
sidering the fact that these researchers shared information on newly found lung
cancer deaths, it is questionable whether any additional lung cancers would
have been found, either in the 79 individuals with unknown vital status, or in
the 15 known dead for whom causes of death were not known by the study's
cut-off date. The latter number was reduced to 10 in subsequent tabulations,
after information on causes of death was located for five individuals (Bayliss,
1980). None of these were lung cancer.
Additional factors that could have contributed to the finding of an
excess risk of lung cancer in Wagoner et al. (1980) are as follows:
1) One lung cancer victim was added to the cohort by Wagoner based upon
a single 4" by 7" personnel card that listed the same day (June 1, 1945) as
the "starting date" and "release date" in the plant. In actuality, the individ-
ual, according to company sources, never reported for work because a preemploy-
ment chest X-ray revealed a lung abnormality. The company paid him for the
time he was being examined, which is why his name and social security number
appeared on a social security earnings report. Bayliss excluded him from his
original cohort based on the information on the same personnel record that
said "did not pass chest X-ray."
2) In a supplemental summation on the epidemiology of beryllium with
respect to the proposed occupational safety and health standard for exposure
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to beryllium (January 13, 1978; prepared by Roth and submitted by Brush Wellman),
it states that 295 white males, who were employed at the Reading plant of
Kawecki-Berylco Industries, in jobs similar or identical to those of the Wagoner
et al. cohort were not included. Of that group the report states that 199 had
a known vital status. One hundred eighty-one were alive and 18 deceased by
the close of the study period. Dr. Roth's post hearing statement indicated
that the inclusion of these additional employees would have increased the
cohort by about 10 percent.
3) In researching the medical files of the 47 lung cancer victims,
David Bayliss, one of the co-authors, discovered that 23 files contained
information to the effect that the individuals in question were smokers. In
addition, the company from which the cohort was derived provided data indica-
ting that 33 of the 47 lung cancer victims (70 percent) smoked cigarettes,
based on a company-sponsored survey by Hooper-Holmes (Kawecki-Berylco Industries
(KBI), 1977). Bayliss determined that of the 47 cases, a total of 42, or
better than 89 percent, smoked cigarettes, based on a combination of smoking
information gathered by the company and smoking information from the medical
files. If this information is accurate, it could indicate the presence of a
confounding effect due to cigarette smoking. Bayliss further established that
one of the remaining 5 cases died from another cause of death. This victim
actually died from a glioblastoma multiforme (astrocytoma) of the brain,
according to medical data. However, his death certificate incorrectly listed
lung cancer as an underlying cause of death. If the 47 cases are reduced to
46, then 91 percent smoked cigarettes.
4) An inadequate discussion was presented on the confounding effects of
exposure to potential carcinogens prior to and following employment in the
beryllium industry. These factors are especially important since the authors
maintain that only short-term employees are affected. Evidence from employment
records, medical files, questionnaires administered during the 1968 NIOSH-
sponsored medical survey of the plant, and death certificates indicates a
distinct possibility that these factors are significant in the cohort under
study (Bayliss, 1980).
Another problem with the Wagoner et al. (1980) study, as stated by the
authors themselves, is that the expected deaths were overestimated by 19 per-
cent because of the use of death rates for white males in the United States as
a whole, rather than those for Berks County, Pennsylvania, where the plant was
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located. This statement was based on a comparison in Mason and McKay (1973)
of the 1950-1969 age-adjusted lung cancer death rate for white males in Berks
County, Pennsylvania, with that of the 1950-1969 age-adjusted lung cancer rate
for white males in the U.S. (Mason and McKay, 1973). Actually, this reference
by Wagoner et al. to "lower" Berks County rates as a justification for the
position that the expected deaths based upon national rates are overestimated,
has been criticized by Roth and Associates (1983) as well as by Bayliss (1980).
Bayliss' criticism cited the fact that the periods of observation were differ-
ent, i.e., that the Mason data covered the period from 1950 through 1969,
while that of Wagoner et al. (1980) covered the period from 1942 through 1975.
Bayliss also pointed out that to derive reliable county death rates from the
existing data would be extremely difficult to do with any confidence. Roth
and Associates criticized the use of Berks County rates as not being reflective
of greatly elevated lung cancer death rates for the City of Reading, which
they maintained were 12 percent higher than the national rates. According to
Roth and Associates (1983), 46 percent of the workers employed by the plant in
1968 resided within the city limits, whereas only 34 percent of Berks County
residents (1970) resided within the city; and therefore, death rates calculated
for Berks County should be weighted toward the relatively higher City of
Reading rates. This adjustment would have the effect of generating comparison
lung cancer rates that are perhaps greater than U.S. rates, and would conse-
quently increase the number of estimated expected deaths.
Wagoner et al. (1980) also claim to have noted an unusual histopathologic
distribution of cell types in the cases of 27 of the 47 lung cancer deaths for
which pathologic specimens could be obtained. Adenocarcinomas were noted in 8
cases (32 percent) out of 25 individuals histologically confirmed to have died
from bronchogenic carcinoma (Smith and Suzuki, 1980). Wagoner et al. apparently
disregarded the conclusion of Smith and Suzuki that "the prevalence of histo-
pathologic cell types of bronchogenic carcinomas among beryllium-exposed
workers could not be presently defined." Smith and Suzuki attributed their
conclusion to the fact that there was "an inadequate response rate for the
submission of pathology specimens for review," since tissue specimens were not
available for 43 percent or 20 of the total number of lung cancers. Wagoner
et al., however, citing data from earlier studies (Haenszel et al. , 1962;
Axtell et al., 1976) to the effect that the frequency of adenocarcinomas in
U.S. white males was 15 or 16 percent, concluded that a significant "shift" of
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histologic cell types was apparent in lung cancer deaths in beryllium workers.
However, an internal NIOSH memorandum (Smith, 1978) stated that more recent
data by Vincent et al. (1977) indicated that a shift in the prevalences of
histopathological cell types of lung cancer in the general population over
time has led to an increase in the prevalence of adenocarcinoma to 24 percent,
and therefore the prevalence of adenocarcinomas in the lung cancer deaths of
beryllium workers is not significantly different from that expected. Smith
suggested in his memorandum that any mention by Wagoner et al. of the histopa-
thological examination of lung tumor specimens that does not take into consid-
eration the unrepresentative nature of the specimens should be deleted from
the paper.
To summarize, it appears that the authors of the Wagoner et al. (1980)
study tended to exaggerate the risk of lung cancer in a population of workers
potentially exposed to beryllium, and underemphasized or did not discuss suffi-
ciently the shortcomings of the study. The net effect was to turn a "suggested
association" of lung cancer with beryllium exposure into a questionable "signi-
ficant association." However, despite the study's problems, there still remains
a possibility that the elevated risk of lung cancer reported therein was due in
part to beryllium exposure, and therefore, the CAG considers the study to be
suggestive.
7.2.5 Infante et al. (1980)
In a companion paper by Infante et al. (1980) which appeared in the same
journal as the Wagoner et al. (1980) study, lung cancer mortality was studied
by the retrospective cohort method in white males for whom data had been
entered into the Beryllium Case Registry (BCR) with diagnoses of beryllium
disease. A person was adjudged to have beryllium disease and thus to be
eligible for inclusion into the BCR if three or more (two were mandatory) of
the following five criteria were met (Hasan and Kazemi, 1974).
Mandatory -- (1) Establishment of significant beryllium exposure based
on sound epidemiologic history.
(2) Objective evidence of lower respiratory tract disease
and a clinical course consistent with beryllium disease.
Mandatory -- (3) Chest X-ray films with radiologic evidence of intersti-
tial fibronodular disease.
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(4) Evidence of restrictive or obstructive defect with
diminished carbon monoxide diffusing capacity by physio-
logic studies of lung function.
(5) 1 - Pathologic changes consistent with beryllium disease
on examination of lung tissue.
2 - Presence of beryllium in lung tissue or thoracic
lymph nodes.
Close to 900 individuals have been entered into the BCR as of the present
date, based in some measure on evidence of non-malignant respiratory disease
objectively determined by appropriate and established medical procedures
(Mullan, 1983).
According to Mullan (1983), the criteria listed above are characterized by
high sensitivity but low specificity in that, while they are able to identify
cases of actual beryllium disease, they can also lead to the inclusion of non-
beryllium disease cases; in particular, cases of sarcoidosis.
Infante et al. eliminated from their cohort all nonwhite and female sub-
jects because of their lack of "statistical sensitivity," and also eliminated
all subjects who were deceased at the time of the BCR entry. The authors
maintain that this constraint was necessary in order to ensure that no bias
would result from the "selective referral of individuals with the outcome
still under investigation," i.e., individuals with lung cancer. The use of
the above procedure, however, raises the question that such a self-imposed
constraint may not have prevented the "selective referral" of lung cancer
victims prior to their deaths. This possible effect might have been eliminated
if the above-referenced limitation had been applied to such cases as well. Or,
alternatively, it should perhaps have been assumed that no potential bias
existed, and that therefore all BCR cases added posthumously should have been
retained.
Altogether, Infante et al. included in their study cohort only 421 members
of the BCR, less than 50 percent of the total. Of these, vital status could
not be determined on 64 (15 percent), while 139 (33 percent) were found to have
died by December 31, 1975. In this latter group, the causes of death could not
be ascertained for 15 individuals. These were placed in an "undetermined cause
of death" category. The authors ceased accumulating person-years on the group
of 64 with unknown vital status at the time each was last known to be alive
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instead of to the end of the study. This procedure served to reduce expected
mortality slightly in every cause category. This reduction was offset, however,
by the fact that no potential deaths that might have occurred during this time
up to the cut-off date in this group of 64 cases were included. With the
intense scrutiny given the issue of lung cancer and beryllium by Infante and
the many research investigators who have worked with the BCR since its incep-
tion (including Wagoner, Bayliss, and Mancuso), it is questionable whether any
of the 15 deaths from undetermined causes, or any of the 64 cases with unknown
vital status, were lung cancer deaths. Hence, it is probable that the esti-
mated lung cancer risk is somewhat overestimated by this procedure.
Additionally, since the same National Institute for Occupational Safety
and Health (NIOSH) life table program that was used to calculate lung cancer
deaths in the Wagoner et al. study was the method used to derive expected lung
cancer deaths in the Infante et al. study, it was subject to the same problems
as mentioned previously, i.e., a +11 percent error in the calculated expected
lung cancer deaths. If it is assumed that this distortion is of the same
magnitude as that described in the discussion of the Wagoner et al. (1980)
study, the SMR of the Infante et al. (1980) study would be inflated by 11 per-
cent also.
As expected, Infante et al. (1980) found a significantly high excess risk
of "non-neoplastic" respiratory disease (52 observed deaths versus 3.17 expec-
ted). In terms of total cancer, 19 deaths were observed versus 12.41 expected.
With respect to lung cancer, 6 deaths occurred more than 15 years after the
onset of beryllium exposure, versus 2.81 expected (P < 0.01). If the expected
deaths are adjusted upwards by 11 percent to compensate for the overestimate
produced by the NIOSH life table program, the authors' P value is reduced to
one of borderline significance (6 observed versus 3.12 expected deaths; P <
0.09).
Infante et al. divided their cohort on the basis of "acute" versus "chronic"
beryllium disease. Subjects were considered "acute" if the BCR records indi-
cated a diagnosis of chemical bronchitis or pneumonitis or other acute respira-
tory illness at time of entry into the registry. Subjects were called "chronic"
if BCR records indicated a diagnosis of pulmonary fibrosis or some recognized
chronic lung condition at time of entry into the registry. All other cases,
if they could not be designated as chronic, were considered by Infante to be
acute if the onset of the disease occurred within one year of initial exposure.
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These definitions should not be confused with the medically accepted defini-
tions of acute and chronic beryllium disease, in which cases of beryllium
disease lasting one year or less are termed "acute," while those lasting
longer than one year are termed "chronic." The authors found no significant
lung cancer, not even an excess in their "chronic" respiratory disease group
of 198 persons (1 observed death versus 1.38 expected). However, in their
"acute" respiratory disease group, they found 6 observed lung cancer deaths
versus 1.91 expected (P < 0.05), and in the interval of more than 15 years
since initial onset of beryllium exposure, 5 observed lung cancer deaths were
found versus 1.56 expected (P < 0.05). These findings, however, suffer from
the same problems previously alluded to regarding the NIOSH life table program,
and must therefore be regarded as questionable with respect to their implica-
tions.
The possibility cannot be discounted that cigarette smoking may have con-
tributed to an excess risk in the Infante et al. (1980) study, despite the
authors' claim that cigarette smoking is unlikely to have played a role in the
somewhat increased lung cancer risk they found. Although the criteria for
inclusion in the BCR have been evolving and undergoing revision to improve
their sensitivity and specificity since the Registry's inception in 1952, it
is possible that in the early years of the Registry, the criteria could have
allowed the inclusion of individuals with respiratory disease either brought
on by or exacerbated by cigarette smoking. Such individuals would then have
been likely candidates for selection into the BCR. Of the seven lung cancer
cases discussed by Infante et al. (1980), six were admitted to the hospitals
for treatment before 1955, and one was admitted in 1964. The ability to
detect subtle radiographic changes consistent with a diagnosis of beryllium
disease was relatively undeveloped in the early 1950s. Given current practices
in the interpretation of X-rays and pulmonary function data, such a misdiagnosis
would be unlikely today.
Any one of the factors referred to above could have been of sufficient
magnitude to produce a significant excess lung cancer risk in the group under
study. The authors' treatment of these confounders serves to exaggerate this
risk without presenting any compensating negatives. It appears likely that
correcting or controlling the influence of two or more of these factors could
reduce the estimated risk calculated to one of nonsignificance. The findings
of Infante et al. (1980) are thus seen to be, at best, only suggestive of an
increased risk of lung cancer from exposure to beryllium.
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7.2.6 Mancuso and El-Attar (1969)
The first in a series of four epidenriological studies of mortality in
workers exposed to beryllium was conducted by Mancuso and El-Attar (1969) on
the same study population as was used in the Bayliss and Wagoner studies. The
cohort in the Mancuso and El-Attar study, however, was derived from quarterly
earnings reports provided by the Social Security Administration. Quarterly
earnings reports on every employee of a given company covered by social security
are filed four times a year by all companies included under the Social Security
Act. These reports generally consist of lists of names, social security
numbers, dates of birth, and reported earnings during the quarters for which
filing is done. With respect to beryllium, Mancuso and El-Attar obtained
quarterly earnings reports for both companies studied by Bayliss et al. and
Wagoner et al., but limited their study to the period of employment from 1937
to 1948. Altogether, they identified 3,685 white males from two beryllium
plants. Only 729 white males were found to have died through the year 1966.
Included in this group were 31 lung cancers (ICD 162-163). The authors con-
trasted internally generated age-, plant-, and period-specific death rates by
cause with internally generated age-specific death rates by cause from an
"industrial control." Unfortunately, because of the small numbers involved,
the authors did not include any employees of age 55 or over. The industrial
cohort used for purposes of comparison was not identified. The 729 deaths
were distributed into 160 narrow subcategories, based on four broad age groups,
two companies, four periods of time, and five broad death categories. Internal
death rates were computed in each subcategory. Because the numbers from which
these internal rates were derived are so small (in some instances nonexistent)
from one subcategory to another, the comparisons with 20 rates generated from
the industrial control are shaky at best and appear to vary considerably. No
trends are evident. No significance tests were done. The data are open to
interpretation. The authors themselves conclude, based on their analysis,
that their data are "severely limited" with respect to answering the question
of carcinogenic risk.
7.2.7 Mancuso (1970)
In the second study of the same cohort, Mancuso (1970) added duration of
employment as a variable, and divided his cohort into a 1937-1944 component
and a 1945-1948 component, by dates of initial employment. Both subgroups
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were followed until 1967, and internal death rates were computed based upon a
technique the author terms "the generation cohort method." Each cohort was
classified into 10-year age groups, beginning with 1940. An average annual
mortality rate was calculated by age as of 1940. Age adjustment was done
through the direct method, using the 1950 standard million as a base population
(presumably the U.S. 1950 standard million, although the author does not state
what his comparison population is). Comparisons were internal by gradient of
exposure as defined by duration of employment and by evidence of prior chemical
respiratory disease.
A higher rate of lung cancer was noted by the author among workers whose
first employment occurred during the period 1937-1944 in age category 25-64,
and who were employed for 5 or fewer quarters (99.9 per 100,000) compared to
those employed 6 quarters or longer (33.2 per 100,000) based on 16 and 4 lung
cancers, respectively. He further found a higher rate in one company among a
group of workers with histories of chemical respiratory illness versus those
who did not have this condition. One hundred forty-two white males with
respiratory illness during the period 1940-1948 were identified in this plant.
Out of a total of 35 deaths occurring to this group, 6 were due to lung cancer.
Based on these 6 lung cancers, an age-adjusted lung cancer death rate of 284.3
per 100,000 was calculated, compared to an age-adjusted rate of 77.7 per
100,000 (based upon 9 lung cancer deaths) in the total cohort of this company's
workers employed from 1937 to 1948. These calculations were confined to
individuals who were in the age group 25 to 64 in the year 1940. For some
unknown reason, the author neglected to include the age group of 15 to 24,
the inclusion of which would have had the effect of increasing the lung cancer
death rate in individuals without prior respiratory illness by the addition of
two lung cancer deaths, while leaving the rate unchanged in those with respira-
tory illness, thus narrowing the difference between the two rates. No signi-
ficance tests were done, and the observations were based upon small numbers, as
was pointed out by the author.
Although Mancuso found elevated risks in these groups, the results are
subject to considerable variability. Mancuso criticized his own study for
several alleged deficiencies. Some of these criticisms seem inappropriate,
while others appear valid for this study and also for later studies by Mancuso
of this same population. The deficiencies, according to Mancuso, consisted of
"the marked influence of labor turnover on duration of employment, perhaps
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induced by the presence of respiratory disease; the inability to define the
specific populations by department, process, or by type or form of beryllium
exposure; the presence of competing causes of death; and the shortness of the
period of observation." Other potential problems with these data, which were
not mentioned by the author, are a lack of consideration of the effects of
smoking and the effects of exposure to potential carcinogens in other jobs the
workers may have had before and after their exposure to beryllium, since the
suggested increase appeared only in "short-term employees." This is discussed
further in a later description of the study (Mancuso, 1979). The author's
conclusion that prior chemical respiratory illness influenced the subsequent
development of lung cancer among beryllium workers may be somewhat overstated,
in view of the many limitations of the study.
7.2.8 Mancuso (1979)
In a third update of an epidemiologic study of white male workers employed
at two beryllium-manufacturing companies in Ohio and Pennsylvania, Mancuso
(1979) conducted a cohort mortality study in which he divided his cohort into
two subgroups, each consisting of former and current employees of the respective
companies. Employees were included in the study if they had worked at any
time during the period from 1942 to 1948. The original source documents, from
which names and social security numbers were derived to form the cohort,
consisted of quarterly earnings reports submitted to the Social Security
Administration. The Ohio cohort consisted of 1,222 white males, of which 334
were deceased. The Pennsylvania cohort consisted of 2,044 white males, of
which 787 were deceased. A life table analysis was performed by NIOSH, utili-
zing U.S. white male age- and period-specific rates (5-year age groupings) to
generate expected lung cancer deaths (ICD 162, 163) through 1974 for the Ohio
cohort, and through 1975 for the Pennsylvania cohort. An excess risk of lung
cancer appeared in the Ohio employees after a lapse of 15 years from the onset
of employment (22 observed versus 9.9 expected, P < 0.01). The same was true
for the Pennsylvania employees (36 observed versus 22.0 expected, P < 0.01)
following a similar latent period. The author noted that this risk was con-
fined principally to workers with less than one year's duration of employment
in the industry. No significant excess risk was noted in workers of either
plant who were employed for more than five years in the industry. The author
concluded, on the basis of this study and the Wagoner et al. (1980) study,
that "there is evidence that beryllium causes cancer in man."
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Several questions must be considered before these conclusions can be
accepted as valid. These data, although derived from social security quarterly
earnings reports and not from personnel records, are not independent of the
data set utilized in the Wagoner et al. (1980) study. Both sets of data were
analyzed through the use of the NIOSH life table program. The expected deaths
generated in both studies are subject to the same influences introduced by the
use of the same life table program, and by the use of the same comparison
rates (U.S. white male lung cancer rates). In addition, the extensive coopera-
tion between Mancuso (at the University of Pittsburgh) and Wagoner (at NIOSH)
in the search for causes of death in the respective cohorts for study, contri-
buted to the inclusion of lung cancer deaths known to one but not the other in
both studies. As mentioned previously, because of the use of the NIOSH life
tables in the Mancuso study, the calculation of expected lung cancer deaths was
on the high side (approximately 11 percent) because of the same artifact invol-
ving the calculation of lung cancer rates for which the Wagoner et al. (1980)
study was criticized. Hence, these results should not be considered independent
of the results of the Wagoner study.
Another problem with this cohort is the use of social security quarterly
earnings reports to constitute a cohort of potentially exposed employees.
These files, for the most part, are limited with respect to the data available.
Only the full name, social security number, and amount paid into the system
each quarter of any given year are provided, and only for covered employees.
An examination of microfilmed records of the reports maintained by the Social
Security Administration shows that there is no possibility of determining from
the reports what jobs these individuals performed for the companies, where
their job stations were located, whether their jobs were on or off the premises,
or whether they had actually been exposed to beryllium, or even precisely when
during the 3-month period they actually started work. And, of course, these
records give no information on workers who were not covered by the Act.
Furthermore, in the period prior to 1942, the social security system was in
the process of being established, and tremendous logistic problems in setting
up the system were being encountered during this time. Because the system was
not fully functional until 1942, millions of employees throughout the country
did not get social security numbers until after that date. Large numbers of
employees refused to join the system because they considered it to be "welfare,"
and many more simply reported their social security numbers inaccurately if at
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all when applying for work. Thus, questions remain concerning the validity of
this cohort.
Another difficulty with the Mancuso (1979) study, as with his earlier
studies, is a lack of discussion of other exposures these workers may have
received. The author observed that the main effect (lung cancer) occurred in
short-term employees more than 15 years after initial employment. These
workers had an opportunity to be exposed to other potential carcinogens at
jobs they may have held prior to or immediately following their short employment
in the beryllium industry. This is a distinct possibility because the beryllium-
manufacturing companies are located in or near heavily industrialized areas of
Ohio (Cleveland, Toledo) and Pennsylvania (Reading). Roth and Associates
(1983) report the presence of several industries in the Lorain, Ohio area in
the period from 1942 to 1948 that conceivably could have provided an opportunity
for short-term employees to receive exposure to potential carcinogens. These
are as follows:
INDUSTRIES IN LORAIN AREA 1942-1948
Company Operations Approx. No. Employees
National Tube Foundry, rolling, extruding, 12,000
(now U.S. Steel) coke ovens
Thew Shovel Foundry, machining, fabricating 2,000
Lorain Products Electrical conductors, 500
fabricating, nonferrous foundry
American Crucible Structural steel parts, machining, 200
fabricating, foundry
Iron Ore Ship Dock Unloading ore ?
Another serious omission of the Mancuso (1979) study is the lack of a
discussion of the effect of cigarette smoking on the target organ of interest,
the lung. With respect to the question of smoking, it would appear likely
that since there was considerable overlapping of this study with the Wagoner
study, it is probable that most of the lung cancer victims in the Pennsylvania
cohort of the Mancuso study were smokers. Hence, it is possible that cigarette
smoking contributed to the increased risk of lung cancer in the Pennsylvania
cohort. No information was provided in the Ohio portion of the Mancuso study
regarding the smoking influence, an exposure of considerable import in lung
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cancer. The findings of significant excesses of lung cancer in both plants
must be seen as limited because of the inadequate consideration of the con-
founding effects of these two likely exposures, the problem with the NIOSH
life table programs, and the inadequate nature of social security quarterly
earnings reports in defining an occupationally exposed cohort for study.
7.2.9 Mancuso (1980)
In the fourth update to his study of workers potentially exposed to
beryllium in two beryllium-manufacturing facilities, Mancuso (1980) found
statistically significant elevated risks of lung cancer in 3,685 white males
employed in the period from 1937 to 1948 and followed until the end of 1976,
when contrasted with viscose rayon workers. The beryllium cohort, as mentioned
earlier, was derived from quarterly earnings reports filed with the Social
Security Administration by the two companies. The only new addition to this
latest update was the introduction of a new comparison population, that of
viscose rayon workers. The source or location of these workers, however, is
not mentioned by the author, who states that the "viscose rayon cohort" was
derived from one company's "complete" file of microfilmed employment data on
employees first hired during the period from 1938 to 1948 and followed until
1976 (a period which began one year later than that of the beryllium cohort).
The origin and description of this group of workers is inadequately discussed,
although the Wagoner et al. (1980) study states that the viscose rayon worker
cohort utilized in the Mancuso (1980) study was located somewhere in the
vicinity of the Mancuso cohort.
Lung cancer mortality experience in the beryllium cohort was contrasted
with that expected based on rates specific to age and duration of employment
generated from the mortality experience of the viscose rayon worker cohort.
Rates were generated in two ways, the first based on the total group of
employees in the viscose rayon industry, and the second based on employees
with permanent assignments to only one department, according to the author.
Presumably, those who exhibited mobility in their employment by moving from
one department to another were excluded from the lung cancer death rate calcula-
tions in the second method. No rationale is presented by the author to explain
why mortality in beryllium workers should be contrasted with expected deaths
derived in these two separate ways. However, the net result was to produce
two separate sets of expected lung cancer rates that differed considerably
7-41
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from each other. Mancuso observed 80 lung cancer deaths in his beryllium
cohort of employees from the two companies combined, as compared to 57.06
expected deaths based on the former set of derived rates and 50.63 expected
deaths based on the latter subset of employees working their entire time in
only one department. The author did not compare his beryllium workers on the
basis of time since onset of employment, but did contrast them by duration of
employment. He found a statistically significant excess risk of lung cancer
in employees who had been employed for one year or less, and also in employees
who had been employed for four or more years by the beryllium companies. No
explanation was forthcoming with respect to the choice of four years of total
employment as the point at which short-term workers should be separated from
long-term workers. In his earlier versions, the author utilized different
durations of employment, i.e., 5 quarters (1 1/4 years) and 5-year duration of
employment categories.
An interesting omission from this study is any consideration of the
effects of latency according to duration of employment. It seems unusual that
a discussion of this topic was not included by Mancuso, since the major output
of the NIOSH life table program, which was utilized by Mancuso, is a set of
tabulations by time since onset of employment. Lung cancers diagnosed within
10 years of initial exposure probably were not a consequence of that exposure.
Furthermore, the designation "duration of employment" is not necessarily
uninterrupted continuous employment. In reality, what is meant is "total
employment" (i.e., periods of time when the employee was not exposed or not
actually working, such as during layoffs and terminations, sickness, vacations,
and leaves of absence between initial employment and final day of employment,
are not counted by the NIOSH life table program in the category "duration of
employment"). Therefore, it is possible that included in the observed deaths
are the deaths of individuals who had worked only a few days for the companies,
and who died from lung cancer 20 years later, as well as individuals who
worked for the companies for many years continuously, but who died within five
years of initial employment.
Additionally, the viscose rayon cohort appears to have been a somewhat
younger population by age at hire than was the beryllium cohort (47.2 percent
in the viscose rayon cohort were hired at under age 25, as compared to
38.4 percent hired at under age 25 in the beryllium cohort). Whether or not
the author adjusted for age differences is questionable. Indeed, at the recent
Peer Review Workshop on the Health Assessment Update for Beryllium (February,
7-42
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1984) sponsored by the U.S. Environmental Protection Agency, an epidemiologist
from NIOSH, Dr. Jean French, expressed concern that the Mancuso age adjustment
in Mancuso's comparison of expected mortality based upon viscous rayon workers
with that of actual mortality from Mancuso's beryllium cohort was "inadequate."
Dr. French reported that NIOSH reanalyzed the data and found serious problems
with Mancuso1s analysis. Efforts to resolve this issue have not been success-
ful through official NIOSH channels. Unsuccessful attempts to obtain the
results of the analysis from NIOSH have made it difficult to determine the
magnitude of impact of the required adjustment on risk estimates. Since the
viscous rayon cohort was younger than the beryllium cohort, the net impact of
an adjustment would be to decrease the gap between observed lung cancer deaths
based upon the beryllium cohort and expected deaths based upon the viscous
rayon cohort.
Another problem concerns the acquisition of cause-of-death data. Some
4.3 percent of the reported deceased members of the viscous rayon cohort
remained without a cause of death, versus only 1.5 percent of the beryllium
cohort. This could potentially lead to a greater underestimate of lung cancer
in the viscous rayon cohort compared to the beryllium cohort if the causes of
death in these two groups were fairly evenly distributed.
As in the earlier studies by the same author, a further difficulty with
this study is its lack of discussion of the confounding effects of smoking and
its disregard of potential exposures received not only while working for the
beryllium companies, but also in jobs prior to and subsequent to employment in
the beryllium industry. This represents a problem particularly because a
large majority of this cohort worked for less than one year. Because the
towns in which the beryllium companies were located were considerably industri-
alized, work in these industries could potentially have produced exposures to
other known or suspected carcinogens. As an example, one of the major employers
in the Lorain, Ohio area in the period from 1942 to 1948 was the National Tube
Company (now U.S. Steel), whose operations involved extensive exposure to coke
ovens. Nothing is revealed in the study of the origin or make-up of the
viscous rayon cohort. What is known about its location comes from the Wagoner
et al. (1980) study in which the authors stated that Mancuso1s viscous rayon
cohort was located in the vicinity of the beryllium companies.
Furthermore, since both cohorts were run utilizing the NIOSH life table
program, both cohorts suffer from the previously discussed 11 percent under-
estimation of expected lung cancer deaths.
7-43
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In conclusion, despite the author's certainty regarding the existence of
a causal relationship between beryllium exposure and lung cancer, the evidence
presented in this study is not convincing because of the many limitations of
the study, as described above. Hence it would appear that the study is at
best only suggestive of an increased risk of lung cancer due to exposure to
beryllium.
7.2.10 Summary of Epidemiologic Studies
Although several studies show a statistically significant excess risk of
lung cancer in individuals exposed to beryllium, all of the studies cited have
deficiencies that limit any definitive conclusion that a true association
exists. Support for a finding of an excess risk of lung cancer in beryllium-
exposed persons consists of evidence from cohort mortality studies of two
companies (Table 7-9) and one cohort mortality study of cases admitted to the
Beryllium Case Registry. None of these studies can be said to be independent
since all are studies of basically the same groups of workers. Extensive
cooperation existed between the authors of all of these studies, even to the
extent of running all cohorts through a NIOSH computer-based life table program
known to produce an 11 percent underestimate of expected lung cancer deaths at
the time. This problem has since been remedied. Furthermore, the authors could
not adequately address the confounding effects of smoking or of exposures
received during prior and subsequent employment in other non-beryllium industries
in the area known to produce potential carcinogens (especially in beryllium
workers with short-term employment). Problems in the design and conduct of
the studies further weaken the strength of the findings. There appeared to be
a tendency on the part of the authors to overemphasize the positive nature of
their results and minimize the contribution of qualifying factors. A list of
these problems is presented in Table 7-10. If the errors detailed in the
preceding paragraphs were corrected and proper consideration given to addressing
the problems described above, the finding of a significant excess risk would
probably no longer be apparent, although the possibility nevertheless remains
that a portion of the reported excess lung cancer risk may in fact be due to
beryllium exposure. Thus, the Carcinogen Assessment Group (CAG) feels that
the findings of these studies must be considered to be at least suggestive.
The International Agency for Research on Cancer (IARC) has concluded that
beryllium and its compounds should be classified as "limited" with respect to
0453/B 7-44
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TABLE 7-9. COMPARISON OF STUDY COHORTS AND SUBCOHORTS OF TWO BERYLLIUM COMPANIES
Bayliss et al .
(1971)
Bayliss and
Lainhart (1972)
Bayliss and
•sj Wagoner (1977)
-PS
en
Wagoner et al .
(1980)
Mancuso and
El-Attar (1969)
Company
where
employed3
KBI, BRUSH
6,818 males
KBI only
3,795 white
males
KBI-Reading
Facility only
3,070 white
males
KBI-Reading
Facility only
3,055 white
males
KBI, BRUSH
3,685 white
males
Source
Personnel
records
Same as
above
Same as
above
Same as
above
Social
Security
Quarterly
Earnings
Reports
Period of Comparison
employment population
1942-1967 U.S. males
1942-1967 U.S. white
males
1942-1967 U.S. white
males
1942-1967 U.S. white
males
1937-1948 Industrial
Control
(Unidentified)
Termination
date of Chief lung .
follow-up cancer results
1967 Total
35~TD), 34.1 (E)
1967 Total
2!T70), 23 (E)
Latency 15 yrs +
14 (0), 13.3 (E)
1975 Total
4670), 33 (E)
(P < 0.05)
Latency 15 yrs +
37 (0), 24 (E)
(P < 0.05)
1975 Total
47 (0), 34.3 (E)
(P < 0.05)
Latency 15 yrs +
20 (0), 10.8 (E)
(P < 0.05)
1966 Equivocal
(continued on the following page)
-------
TABLE 7-9. (continued)
Company
where
employed
Mancuso (1970) KBI, BRUSH
3,685 white
males
Mancuso (1979) KBI-2044
BRUSH-1,222
white males
Source
Social
Security
Quarterly
Earnings
Reports
Same
Period of
employment
1937-1944
and
1945-1948
1942-1948
Comparison
population
Internal
Control
U.S. white
males
Termination
date of
fol low- up
1966
Chief lung .
cancer results
Duration of employment
(rate)
> 1 1/4 yrs 33.2/10°
< 1 1/4 yrs 99.9/105
Prior respiratory disease only
BRUSH
1974
KBI
1975
with 284.3/10a
without 77.7/105
Latency 15 yrs + only
Ohio - 22 (0), 9.9 (E)
(P < 0.01)
Pennsylvania - 36 (0),
(P < 0.01)
Mobility (deaths)
22 (E)
aKBI = Kawecki-Berylco Industries (Pennsylvania).
BRUSH = Brush Beryllium Co. (Ohio).
(0) = observed
(E) = expected
Among departments
80 (0), 57.1 (E)
(P < 0.01)
Mancuso (1980)
KBI Same
3,685 white
males
1937-1948 Viscous
rayon
workers
1976 Remained in same department
80 (0), 50.6 (E)
(P < 0.01)
-------
TABLE 7-10. PROBLEMS WITH BERYLLIUM COHORT STUDIES
Bayliss et al. (1971)
Bayliss and Lainhart (1972)
Bayliss and Wagoner (1977)
and
Wagoner et al. (1980)
Mancuso and El-Attar (1969)
Mancuso (1970)
Mancuso (1979)
Mancuso (1980)
A. Loss of 2,000 individuals because of insufficient
data.
B. No latency considerations.
C. Combined study populations of several plants from
2 companies.
A. Includes clerical and administrative personnel with
no exposure.
B. No independent assessment plant employment files.
C. Latency after 20 years not assessed.
A. Cigarette smoking a possible confounder.
B. Overestimate of lung cancer deaths in comparison
population by 11 percent.
C. Inclusion of 1 lung cancer victim who did not fit
definition for inclusion.
0. Loss of 295 individuals from study cohort.
E. Exposure to potential carcinogens prior and post
beryllium employment.
A. Unidentified comparison population.
B. Internal rates based upon small numbers.
C. Tremendous variability and impossible to test
significance.
D. No smoking consideration as possible confounder.
A. Internal rates based upon small numbers.
B. Inappropriate comparison (age group 15-24 left out
of comparison).
C. No consideration of smoking as a possible confounder.
D. No consideration of latency.
E. Exposure to potential carcinogens prior and post
beryllium employment.
A. Overestimate of lung cancer deaths in comparison
population by 11 percent.
B. No consideration of smoking as a possible confounder.
C. Incomplete delineation of cohort from use of Social
Security Quarterly Earnings reports.
D. Exposure to potential carcinogens prior and post
beryllium employment.
A. No consideration of latent effects.
B. Probable lack of age adjustment.
C. No consideration of effects of smoking.
D. No description of origin or makeup of comparison
cohort except for age.
E. Overestimate of lung cancer deaths in comparison
population by 11 percent.
7-47
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the human epidemiologic evidence of carcinogem'city. The CAG regards the
epidemiologic evidence of beryllium carcinogem'city in beryllium-exposed
workers as limited to inadequate.
7.3 QUANTITATIVE ESTIMATION
This quantitative section deals with estimation of the unit risk for
beryllium as a potential carcinogen in air, and compares the potency of beryl-
lium to other carcinogens that have been evaluated by the CAG. The unit risk
for an air pollutant is defined as the incremental lifetime cancer risk to
0
humans from daily exposure to a concentration of 1 ug/m of the pollutant in
air by inhalation.
The unit risk estimate for beryllium represents an extrapolation below
the dose range of experimental data. There is currently no solid scientific
basis for any mathematical extrapolation model that relates exposure to cancer
risk at the extremely low concentrations, including the unit concentration
given above, that must be dealt with in evaluating environmental hazards. For
practical reasons, the correspondingly low levels of risk cannot be measured
directly either by animal experiments or by epidemiologic study. Low-dose ex-
trapolation must, therefore, be based on current understanding of the mechanisms
of carcinogenesis. At the present time, the dominant view of the carcinogenic
process involves the concept that most cancer-causing agents also cause irre-
versible damage to DMA. This position is based in part on the fact that a
very large proportion of agents that cause cancer are also mutagenic. There
is reason to expect that the quanta! response that is characteristic of muta-
genesis is associated with a linear (at low doses) nonthreshold dose-response
relationship. Indeed, there is substantial evidence from mutagenicity studies
with both ionizing radiation and a wide variety of chemicals that this type of
dose-response model is the appropriate one to use. This is particularly true
at the lower end of the dose-response curve; at high doses, there can be an
upward curvature, probably reflecting the effects of multistage processes on
the mutagenic response. The linear (at low doses) nonthreshold dose-response
relationship is also consistent with the relatively few epidemiologic studies
of cancer responses to specific agents that contain enough information to make
the evaluation possible (e.g., radiation-induced leukemia, breast and thyroid
cancer, skin cancer induced by arsenic in drinking water, liver cancer induced
7-48
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by aflatoxins in the diet). Some supporting evidence also exists from animal
experiments (e.g., the initiation stage of the two-stage carcinogenesis model
in rat liver and mouse skin).
Because its scientific basis, although limited, is the best of any of the
current mathematical extrapolation models, the nonthreshold model, which is
linear at low doses, has been adopted as the primary basis for risk extrapola-
tion to low levels of the dose-response relationship. The risk estimates made
with such a model should be regarded as conservative, representing a plausible
upper limit for the risk: i.e., the true risk is not likely to be higher than
the estimate, but it could be lower.
For several reasons, the unit risk estimate based on animal bioassays is
only an approximate indication of the absolute risk in populations exposed to
known carcinogen concentrations. First, there are important species differ-
ences in uptake, metabolism, and organ distribution and elimination of carcin-
ogens, as well as species differences in target site susceptibility, immunolog-
ical responses, hormone function, dietary factors, and disease. Second, the
concept of equivalent doses for humans as compared to animals on a mg/surface
area basis is virtually without experimental verification as regards carcino-
genic response. Finally, human populations are variable with respect to
genetic constitution and diet, living environment, activity patterns, and
other cultural factors.
The unit risk estimate can give a rough indication of the relative
potency of a given agent as compared with other carcinogens. Such estimates
are, of course, more reliable when the comparisons are based on studies in
which the test species, strain, sex, and routes of exposure are similar.
The quantitative aspect of carcinogen risk assessment is addressed here
because of its possible value in the regulatory decision-making process, e.g.,
in setting regulatory priorities, evaluating the adequacy of technology-based
controls, etc. However, the imprecision of presently available technology for
estimating cancer risks to humans at low levels of exposure should be recog-
nized. At best, the linear extrapolation model used here provides a rough but
plausible estimate of the upper limit of risk—that is, with this model it is
not likely that true risk would be much more than the estimated risk, but it
could be considerably lower. The risk estimates presented in subsequent
sections should not be regarded, therefore, as accurate representations of the
true cancer risks even when the exposures involved are accurately defined.
7-49
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The estimates presented may, however, be factored into regulatory decisions to
the extent that the concept of upper-risk limits is found to be useful.
7.3.1 Procedures for the Determination of Unit Risk
7.3.1.1 Low-Dose Extrapolation Model—Two dose-response models, which are
derivatives of the theory of multistage carcinogenesis, are used to calculate
the unit risk of beryllium on the basis of animal data. The selection of
these two models is dictated by the nature of the data available for quanti-
tative risk assessment. The first model, a multistage model that allows for a
time-dependent dose pattern, was developed by Crump and Howe (1984), and uses
the theory of multistage carcinogenesis developed by Armitage and Doll (1961).
The Armitage-Doll multistage model assumes that a cell is capable of generating
a neoplasm when it has undergone k changes in a certain order. The rate, r.,
t* h
of the i change is assumed to be linearly related to D(t), the dose at age
t, i.e., r. = a. + b.D(t), where a. is the background rate, and b. is the
proportionality constant for the dose. It can be shown that the probability
of cancer by age t is given by
P(t) = 1 - exp [-H(t)]
where
H(t) = J k_ ; 2
[(ak + bkD(uk)]} du1. ..duR
is the cumulative incidence rate by time t.
When H(t) or the risk of cancer is small, P(t) is approximately equal to
H(t). When only one stage is dose-related, all proportionality constants are
zero except for the proportionality constant for the dose-related stage.
This model will be applied to the data in Reeves and Deitch (1969) where
the dose D(t) is constant for t in an interval [S, , S?] and is zero elsewhere.
Under this particular exposure pattern and the assumption that only a single
stage is dose-related, the term H(t) can be written as the sum of two components
l<
H-,(t) and H?(t) where H-,(t) = a-, • a2 . . . a. t /k! represents the background
cumulative incidence and H?(t) is the incremental cumulative incidence due to
exposure. Three special cases of HL which are often used to interpret a given
set of data are given below.
7-50
-------
t <
Mt) = dbi(nai} (t - s )k s < t < s,
k! a i k k
1 (t - SI)K - (t - s2)K s2 < t
if the first stage is affected (r = 1),
0 t < s
i
• r
2
H,(t) = dbk-l(nai) v tk - s, [kt - (k - l)s,] s, < t < s
^_ i * xQ J. -A. -L
k!ak-l
k-1 k-1
s2 [kt - (k-l)s2] - s1 [kt - (k-Ds-j^] s2 < t
if the penultimate stage is affected (r = k - 1), and
0 t < s1
H2(t) = ynV x tk - sk Sl < t
k k . .
s2 - sl s2 < t
if the last stage is affected (r = k).
A computer program, ADOLL1-83, has been developed by Crump and Howe
(1984) to implement the computational aspect of the model. In this program,
the model is generalized to include tumor induction time I by replacing the
time factor t by t-I. The best-fit model is identified as the one that has
the maximum likelihood, among various models with different numbers of stages
and the stage affected by the exposure.
The second model used to calculate the carcinogenic potency of beryllium
is the one-hit model with zero background rate. This model is used because
all the experiments, except that of Reeves and Deitch (1969), had only one
data point and did not have a control group. The slope, b, of the one-hit
model, P(d) = 1 - exp(-bxd), is calculated by the formula
7-51
-------
b = [-Ln(l-P)]/d
Since the background rate is zero, the least-square estimate b, as calculated
above, is also a maximum- likelihood estimate.
7.3.1.2 Selection of Data—For some chemicals, several studies in different
animal species, strains, and sexes, each run at several doses and different
routes of exposure, are available. A choice must be made as to which of the
data sets from several studies to use in the model. It may also be appro-
priate to correct for metabolism differences between species and for absorp-
tion factors via different routes of administration. The procedures used in
evaluating these data are consistent with the approach of making a maximum-
likely risk estimate. They are as follows:
1. The tumor incidence data are separated according to organ sites or
tumor types. The set of data (i.e., dose and tumor incidence) used in the
model is the set where the incidence is statistically significantly higher
than the control for at least one test dose level and/or where the tumor
incidence rate shows a statistically significant trend with respect to dose
level. The data set that gives the highest estimate of the lifetime carcin-
ogenic risk, q?, is selected in most cases. However, efforts are made to
exclude data sets that produce spuriously high risk estimates because of a
small number of animals. That is, if two sets of data show a similar dose-
response relationship, and one has a very small sample size, the set of data
having the larger sample size is selected for calculating the carcinogenic
potency.
2. If there are two or more data sets of comparable size that are
identical with respect to species, strain, sex, and tumor sites, the geometric
mean of q?, estimated from each of these data sets, is used for risk assessment.
The geometric mean of numbers A-,, A^, •••, A, is defined as
x . . . x A
1/m
m
3. If two or more significant tumor sites are observed in the same
study, and if the data are available, the number of animals with at least one
of the specific tumor sites under consideration is used as incidence data in
the model.
7-52
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7.3.1.3 Calculation of Human Equivalent Dosages—Pol lowing the suggestion of
Mantel and Schneiderman (1975), it is assumed that mg/surface area/day is an
equivalent dose between species. Since, to a close approximation, the surface
area is proportional to the two-thirds power of the weight, as would be the
case for a perfect sphere, the exposure in mg/day per two-thirds power of the
weight is also considered to be equivalent exposure. In an animal experiment,
this equivalent dose is computed in the following manner.
Let
L = duration of experiment
1 = duration of exposure
m = average dose per day in mg during administration of the agent (i.e.,
during 1 ), and
W = average weight of the experimental animal.
Then, the lifetime exposure is
1 x m
7.3.1.3.1 Oral Exposure. Often exposures are not given in units of mg/day,
and it becomes necessary to convert the given exposures into mg/day. Similarly,
in drinking water studies, exposure is expressed as ppm in the water. For
example, in most feeding studies exposure is given in terms of ppm in the
diet. In these cases, the exposure in mg/day is
m = ppm x F x r
where ppm is parts per million of the carcinogenic agent in the diet or water,
F is the weight of the food or water consumed per day in kg, and r is the
absorption fraction. In the absence of any data to the contrary, r is assumed
to be equal to one. For a uniform diet, the weight of the food consumed is
proportional to the calories required, which in turn is proportional to the
surface area, or two-thirds power of the weight. Water demands are also
assumed to be proportional to the surface area, so that
7-53
-------
2/3
m a ppm x W x r
or
m
rW2/3
ppm
As a result, ppm in the diet or water is often assumed to be an equivalent
exposure between species. However, this may not be justified for the present
study, since the ratio of calories to food weight is very different in the
diet of man as compared to laboratory animals, primarily due to differences in
the moisture content of the foods eaten. For the same reason, the amount of
drinking water required by each species also differs. It therefore would be
necessary to use an empirically-derived factor, f = F/W, which is the fraction
of an organism's body weight that is consumed per day as food, expressed as
follows:
Fraction of body
weight consumed as
Species
Man
Rats
Mice
Thus, when the exposure is given as a certain dietary or water concentration
2/3
in ppm, the exposure in mg/W is
x f x W = ppm x f x wl/3
W
70
0.35
0.03
ffood
0.028
0.05
0.13
water
0.029
0.078
0.17
rW2/3 w2/3 w2/3
When exposure is given in terms of mg/kg/day = m/Wr = s, the conversion is
simply
m S X W1/3
rW2/3
7-54
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7.3.1.3.2 Inhalation Exposure. When exposure is via inhalation, the calcula-
tion of dose can be considered for two cases where 1) the carcinogenic agent
is either a completely water-soluble gas or an aerosol and is absorbed propor-
tionally to the amount of air breathed in, and 2) where the carcinogen is a
poorly water-soluble gas which reaches an equilibrium between the air breathed
and the body compartments. After equilibrium is reached, the rate of absorp-
tion of these agents is expected to be proportional to the metabolic rate,
which is proportional to the rate of oxygen consumption, which in turn is a
function of surface area.
7.3.1.3.2.1 Case 1. Agents that are in the form of particulate matter
or virtually completely absorbed gases, such as sulfur dioxide, can reasonably
be expected to be absorbed proportionally to the breathing rate. In this case
the exposure in mg/day may be expressed as
m = I x v x r
3 3
where I = inhalation rate per day in m , v = mg/m of the agent in air, and r
= the absorption fraction.
The inhalation rates, I, for various species can be calculated from the
observations of the Federation of American Societies for Experimental Biology
(FASEB, 1974) that 25-g mice breathe 34.5 liters/day and 113-g rats breathe
105 liters/day. For mice and rats of other weights, W (in kilograms), the
surface area proportionality can be used to find breathing rates in m /day as
follows:
For mice, I = 0.0345 (W/0.025)2/3 m3/day
o/o o
For rats, I = 0.105 (W/0.113) m /day
o
For humans, the value of 20 m /day* is adopted as a standard breathing rate
(International Commission on Radiological Protection, 1977). The equivalent
2/3
exposure in mg/W for these agents can be derived from the air intake data
in a way analogous to the food intake data. The empirical factors for the air
'From "Recommendation of the International Commission.^ Radiological Protec-
tion ,"7page 9. The average breathing rate is 10 cm per 8-hour workday and
2 x 10 cm0 in 24 hours.
7-55
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intake per kg per day, i = I/W, based upon the previously stated relationships,
are tabulated as follows:
Species W i = I/W
Man
Rats
Mice
70
0.35
0.03
0.29
0.64
1.3
Therefore, for particulates or completely absorbed gases, the equivalent
2/3
exposure in mg/W is
, _ _ m _ Ivr _ iWvr _ -wl/3wv,
d ~ " ~ " ~ ~ ~ 1W vr
In the absence of experimental information or a sound theoretical argument
to the contrary, the fraction absorbed, r, is assumed to be the same for all
species.
7.3.1.3.2.2 Case 2. The dose in mg/day of partially soluble vapors is
2/3
proportional to the 02 consumption, which in turn is proportional to W and
to the solubility of the gas in body fluids, which can be expressed as an
absorption coefficient, r, for the gas. Therefore, expressing the 09 consump-
tion as Op = k W , where k is a constant independent of species, it follows
that
2/3
m=kW xvxr
or
d = _JL = kvr
,w2/3
As with Case 1, in the absence of experimental information or a sound theoreti-
cal argument to the contrary, the absorption fraction, r, is assumed to be the
same for all species. Therefore, for these substances a certain concentration
in ppm or ug/m in experimental animals is equivalent to the same concentration
in humans. This is supported by the observation that the minimum alveolar
concentration necessary to produce a given "stage" of anesthesia is similar in
man and animals (Dripps et al . , 1977). When the animals are exposed via the
oral route and human exposure is via inhalation or vice versa, the assumption
7-56
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is made, unless there is pharmacokinetic evidence to the contrary, that absorp-
tion is equal by either exposure route.
7.3.1.4 Calculation of the Unit Risk from Animal Studies—The risk associated
with d mg/kg /day is obtained from GLOBAL79, and for most cases of interest
to risk assessment, can be adequately approximated by P(d) = 1 - exp (-q*d). A
"unit risk" in units X is simply the risk corresponding to an exposure of X =
2/3
1. This value is estimated by finding the number of mg/kg /day that corres-
ponds to one unit of X, and substituting this value into the above relationship.
3
Thus, for example, if X is in units of ug/m in the air, then for case 1, d =
1/3 -3 ?/3 3
0.29 x 70 x 10 mg/kg^Yday, and for case 2, d = 1, when ug/m is the
unit used to compute parameters in animal experiments.
If exposures are given in terms of ppm in air, the following calculation
may be used:
3
1 ppm = 1.2 x mo1ecu1ar weight (gas) mg/m
molecular weight (air)
Note that an equivalent method of calculating unit risk would be to use mg/kg
for the animal exposures, and then to increase the j polynomial coefficient
by an amount
(Wh/Wa)J/3 j = 1, 2, .... k,
and to use mg/kg equivalents for the unit risk values.
7.3.1.4.1 Adjustments for Less Than Lifespan Duration of Experiment. If the
duration of experiment Lg is less than the natural lifespan of the test animal
L, the slope q* or more generally the exponent g(d), is increased by multiply-
3
ing by a factor (L/l_e) . We assume that if the average dose d is continued,
the age-specific rate of cancer will continue to increase as a constant func-
tion of the background rate. The age-specific rates for humans increase at
least by the second power of the age and often by a considerably higher power,
as demonstrated by Doll (1971). Thus, it is expected that the cumulative
tumor rate would increase by at least the third power of age. Using this fact,
it is assumed that the slope q*, or more generally the exponent g(d), would
also increase by at least the third power of age. As a result, if the slope
q* [or g(d)] is calculated at age L , it is expected that if the experiment
7-57
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had been continued for the full lifespan L at the given average exposure, the
slope q* [or g(d)] would have been increased by at least (L/L ) .
This adjustment is conceptually consistent with the proportional hazard
model proposed by Cox (1972) and the time-to-tumor model considered by Daffer
et al. (1980), where the probability of cancer by age t and at dose d is given
by
P(d,t) = 1 - exp [-f(t) x g(d)]
7.3.1.5 Model for Estimation of Unit Risk Based on Human Data—If human epi-
demiologic studies and sufficiently valid exposure information are avail-
able for the compound, they are always used in some way. If they show a car-
cinogenic effect, the data are analyzed to give an estimate of the linear
dependence of cancer rates on lifetime average dose, which is equivalent to
the factor B,,. If they show no carcinogenic effect when positive animal
evidence is available, then it is assumed that a risk does exist, but it is
smaller than could have been observed in the epidemiologic study, and an upper
limit to the cancer incidence is calculated assuming hypothetically that the
true incidence is below the level of detection in the cohort studied, which is
determined largely by the cohort size. Whenever possible, human data are used
in preference to animal bioassay data.
Very little information exists that can be utilized to extrapolate from
high-exposure occupational studies to exposures at low environmental levels.
However, if a number of simplifying assumptions are made, it is possible to
construct a crude dose-response model whose parameters can be estimated using
vital statistics, epidemiologic studies, and estimates of worker exposures.
In human studies, the response is measured in terms of the relative risk
of the exposed cohort of individuals as compared with the control group. The
mathematical model employed for low-dose extrapolation assumes that for low
exposures the lifetime probability of death from cancer, PO, may be repre-
sented by the linear equation
PQ = A + BHx
where A is the lifetime probability in the absence of the agent, and x is the
average lifetime exposure to environmental levels in units such as ppm. The
7-58
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factor BH is the increased probability of cancer associated with each unit
increase of x, the agent in air.
If it is assumed that R, the relative risk of cancer for exposed workers
as compared to the general population, is independent of length of exposure or
age at exposure, and depends only upon average lifetime exposure, it follows
that
A + B (X + X)
P0 " A * BH
or
RPQ = A + BH (x1 + x2)
where x-, = lifetime average daily exposure to the agent for the general popula-
tion, Xp = lifetime average daily exposure to the agent in the occupational
setting, and PQ = lifetime probability of dying of cancer with no or negligible
exposure.
Substituting Pfi = A + B,, (x, ) and rearranging gives
BH = P0 (R - D/x2
To use this model, estimates of R and x? must be obtained from epidemiologic
studies. The value P~ is derived by means of the life table methodology from
the age- and cause-specific death rates for the general population found in
U.S. vital statistics tables.
7.3.2 Estimation of the Carcinogenic Risk of Beryllium
7.3.2.1 Calculation of the Carcinogenic Potency of Beryllium on the Basis of
Animal Data — Only the data from inhalation studies are used for risk assessment
because the route of administration is an exposure route of interest to humans.
Although there are many animal studies showing carcinogenic effects of beryllium
by inhalation, the data that can be used for estimating the carcinogenic risks
associated with beryllium are very limited. Except for Reeves and Deitch
(1969), most of the studies were not well documented, were conducted at single
dose levels, and did not include control groups. In Reeves and Deitch (1969),
7-59
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animals were exposed to nine different dose patterns, varying in the duration
of exposure and the time at which exposure was begun and terminated. The data
from Reeves and Deitch (1969) and seven other studies that had only single
dose levels are used herein to calculate the carcinogenic potency of beryllium.
For the Reeves and Deitch data, the multistage model with time-dependent dose
patterns is used as the low-dose extrapolation model. The data and the calcu-
lations are presented in Appendix A. For the studies with single dose levels,
the one-hit model, as described in Section 7.3.1.1, is used as the low-dose
extrapolation model. The data for the seven studies with single dose levels,
and potency estimates on the basis of all eight of the data sets, are presented
in Table 7-11.
In all of these calculations, the equivalent dose d is arrived at by
using the procedure described as Case 1 in Section 7.3.1.3.2.1. This procedure
3
is illustrated as follows: For 1 ug/m of beryllium in air, the total beryllium
3 3
intake for a rat weighing 0.35 kg is I. = 1 ug/m x 0.224 m /day = 0.224
3
ug/day, where 0.224 m /day is assumed to be the volumetric breathing rate for
a rat weighing 0.35 kg. Assuming that doses are equivalent among species on
3
the basis of surface area, the human equivalent dose C (ug/m ) satisfies the
equation
(20 m3/day) x C (ug/m3)/(70)2/3 = 0.224/(0.35)2/3
3 3
or C = 0.38 ug/m , where 20 m /day is assumed to be the volumetric breathing
3
rate for a 70-kg human. Therefore, the human equivalent dose in |jg/m is
obtained by multiplying the experimental dose by 0.38. The last column of
Table 7-11 presents the carcinogenic potency of beryllium as calculated from
each of the eight inhalation studies. The potency level ranges from 2.9 x
-33 3
10 /(ug/m ) to 4.4/(ug/m ). The magnitude of the potency appears to depend
upon the form of beryllium used in the experiment. Beryl ore is the least
potent compound among the four compounds studied, while beryllium sulfate
(BeSO.) is the most potent. Four of the five studies on beryllium sulfate
o
(BeSO.) have potency estimates that approximate 0.5/(ng/m ).
7.3.2.2 Calculation of the Carcinogenic Potency of Beryllium on the Basis
of Human Data—Given the need to estimate the cancer risk of beryllium and the
uncertainty inherent in the use of animal data, it is desirable to use the
7-60
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TABLE 7-11. BERYLLIUM DOSE-RESPONSE DATA FROM SEVEN INHALATION STUDIES ON RATS, AND THE CORRESPONDING
POTENCY (SLOPE) ESTIMATIONS
I
cr>
Investigator
Vorwald (1953)
Schepers (1957)
Schepers (1961)
Schepers (1961)
Vorwald et al. (1966)
Reeves and
Deitch (1969)
Wagner et al .
(1969)
Reeves and Deitch
(1969)
Mean beryllium
concentration Standardized
Beryllium (uQ/m ) experimental
compound exposure pattern dose (ug/m )
BeSO 33 ug Be/m3 5.0
35 hours/week for
13 months
BeSO. 33.5 ug Be/m3 2.9
35 hours/week for
7. 5 months
BeHPO. 227 ug Be/m3 17.1
35 hours/week for
6. 5 months
BeF2 9 ug Be/m3 1.1
35 hours/week for
10.5 months
BeSO. 2.8 ug Be/m3 0.58
35 hours/week for
18 months
BeSO. 35.7 ug Be/m3 7.4
35 hours/week for
18 months
o
beryl ore 620 ug Be/m 585.6
intermittantly
for 17 months
BeSO. See Appendix A for
details
Pulmonary
tumor
incidence
rate
4/8
58/136
7/40 '
11/200
13/21
13/15
9/19
Human
equivalent
dose ,
(ug Be/mJ)
1.9
1.1
6.5
0.42
0.22
2.8
222.5
Maximum
likelihood .
estimate, slope
(ug/mY1
0.36
0.51
3.0X10"2
0.13
4.4
0.72
2.9X10"3
0.81
'Standardized experimental dose is calculated by d x (h/168) x (L/18) where d is the mean experimental concentration,
h is the number of hours exposed per week (168 hours), and L is the number of months exposed.
bEstimated by assuming that the control response is zero.
Source: Reeves, 1978.
-------
available human data in some way to estimate the carcinogenic potency of
beryllium. Data from Mancuso (1979) and a sub-cohort from Wagoner et al.
(1980) are considered appropriate for this purpose. The reason these two
studies were selected is that their cohorts consisted of beryllium workers
employed prior to 1949, when controls on beryllium in the workplace began.
The workers' exposures to beryllium before 1949 were very high. A 1947 study
reviewed by NIOSH (1972) reported beryllium concentrations in a beryllium
3
extraction plant in Pennsylvania of up to 8,840 (jg/m . In more than 50 per-
cent of the determinations reviewed, beryllium concentrations were in excess
3
of 100 jjg/m . According to NIOSH (1972), the levels of environmental exposure
to beryllium in the workplace were markedly reduced after control measures
were instituted in 1949. In one Ohio extraction plant, the beryllium exposure
3
levels were recorded at 2 |jg/m or less during almost all of a 7-year period.
We summarize below the information available about beryllium exposure levels
in the workplace and the excess cancer risk observed among workers employed in
beryllium production plants.
7.3.2.2.1 Information on Exposure Levels. The beryllium production plants
studied by Mancuso (1979) and Wagoner et al. (1980) were major beryllium
production plants in Pennsylvania and Ohio. The workplace concentrations of
beryllium in these plants were found to be comparable (Eisenbud, 1983). Based
on the NIOSH (1972) report described previously, the lower-bound estimate of
3
the median exposure concentration exceeded 100 ug/m since more than 50 per-
cent of the determinations exceeded that level. To sharpen the estimate, if
we assume that the logarithmic transformation of the concentration follows
log-normal distribution and that the values of 100 and 8,840 pg/m correspond,
respectively, to the 45th and the 95th percentiles of the determinations, then
3
the median value would approximately equal 160 ug/m . According to Eisenbud
and Lisson (1983), it is likely this value is an underestimation of the actual
median exposure level in the workplace, and thus should be considered to be a
lower-bound estimate of the median level. Eisenbud and Lisson (1983) stated
"...published studies of conditions in the Pennsylvania production plant
indicate that the levels of exposure prior to installation of dust controls
were comparable to conditions in the Ohio plants. Concentrations in excess of
1,000 ug/m were commonly found in all three extraction plants during the late
1940's." On the other hand, it is unlikely that the median level could greatly
exceed 1,000 |jg/m , since at that level almost all of the exposed workers
7-62
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developed acute respiratory diseases (Eisenbud, 1955). Thus, it is reasonable
to assume that the median level of beryllium concentration did not exceed
3
1,000 ug/m . In the risk calculation, the median level of beryllium concentra-
3 3
tion is assumed to range from 160 ug/m to 1,000 ug/m . This is the narrowest
range for median exposure that we could obtain on the basis of available
information.
7.3.2.2.2 Information on Excess Risk.
7.3.2.2.2.1 Mancuso (1979). In this study, cohorts of beryllium-exposed
workers employed in two major beryllium production plants, one in Ohio (1,222
workers) and another in Pennsylvania (2,044 workers), during 1942-1948, were
identified from records of the Social Security Administration. Follow-ups
were performed through 1974 for the Ohio cohort and through 1975 for the
Pennsylvania cohort. The worker turnover rates in these cohorts were very
high. For most of the workers, the duration of employment was less than 5
years. It is possible that the workers for whom duration of employment was
less than 5 years were exposed to higher concentrations of beryllium than
those for whom duration of employment was longer than 5 years. Since the
installation of the control measures in 1949 had significantly reduced beryl-
lium concentrations in the plant, a longer duration of employment does not
necessarily imply a greater total cumulative exposure. Table 7-12 presents
the observed and expected lung cancer deaths among white male workers who were
employed at least 15 years ago at the end of follow-up. The duration of
employment did not appear to correlate with the lung cancer mortality rate, a
finding that could be explained in several ways. One possible explanation is
that the workers with shorter duration of employment may have been exposed to
higher concentrations of beryllium than the workers with longer duration of
employment. The Working Group on Beryllium (IARC, 1980) observed that short
exposure to beryllium was also correlated to the "chemical respiratory illness"
which occurred only when exposure exceeded a certain level of concentration
(Eisenbud, 1955).
7.3.2.2.2.2 Wagoner et al. (1980). Wagoner et al. (1980) conducted a
cohort study of 3,055 white males who were initially employed in a plant in
Pennsylvania during 1942 to 1967, and who were followed to December 30, 1975.
Of particular interest to the present risk assessment is a subcohort of workers
who were initially employed prior to 1950 and who were followed for at least
15 years from the date of initial employment. A significant elevation of lung
7-63
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TABLE 7-12. OBSERVED/EXPECTED LUNG CANCER DEATHS (RELATIVE RISK) AMONG
WHITE MALE WORKERS WHO WERE EMPLOYED AT LEAST 15 YEARS
AGO AT THE END OF FOLLOW-UP
Duration of employment (years)
Plant
Ohio
Pennsylvania
<1
14/6.48
(2.16)
23/12.84
(1.79)
1-4
5/1.74
(2.87)
10/5.27
(1.90)
>5
3/1.63
(1.84)
3/3.91
(0.77)
Total
22/9.86
(2.23)
36/20.02
(1.67)
Source: Mancuso, 1979.
cancer risk (24 observed vs. 13.42 expected, or a relative risk of 1.79) was
observed in this subcohort.
Although there is great uncertainty about the adequacy of the epidemic-
logic studies considered herein, the use of a particular relative risk estimate
in the risk calculation should not be affected because all of the relative
risk estimates have values of approximately 2. Even if all of the studies
were negative, a statistical upper-bound estimate of a relative risk would be
approximately equal to the reported value. Thus, the adequacy of the studies
would affect only the conclusion as to whether or not beryllium is carcinogenic
to humans and is not of great relevance to the risk estimation. A major
uncertainty of the risk estimate for beryllium comes from the derivation of
exposure level in the workplace and the temporal effect of the patterns of
exposure. To account for these uncertainties, the "effective" exposure level
of concentration is calculated in several ways.
To calculate the lifetime cancer risk on the basis of information described
previously, the median level of beryllium exposure must be converted to the
"effective" dose through multiplying by a factor of (8/24) x (240/365) x (f/L)
to reflect that workers were exposed to beryllium 8 hours/day, 240 days/year
for f years out of a period of L years at risk (i.e. , from the onset of employ-
ment to the termination of follow-up). Two values of f/L are used in the
calculation: f/L = 1 and f/L = 0.25. The use of f/L = 1 would avoid overesti-
mating the risk (but could underestimate the risk) if the observation by
Reeves and Deitch (1969) that tumor yield depends not on length of exposure
but on how early in life the exposure occurs. Table 7-13 presents a range of
7-64
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TABLE 7-13. CANCER POTENCY ESTIMATES CALCULATED UNDER VARIOUS ASSUMPTIONS
Beryllium
concentration
in workplace
(ug/m3)
"Effective"
f/L dose (ug/ni )a
Relative risk
Cancer potency
)
2.23
160 1 35.07 1.67
1.79
2.23
0.25 8.77 1.67
1.79
2.23
1,000 1 219.18 1.67
1.79
2.23
0.25 54.79 1.67
1.79
1.26 x 10" 5
— n
6.88 x 10 ;
8.11 x 10 *
-3
5.04 x 10 X
2.75 x 10,
3.24 x 10"-3
-4
2.02 x 10 ;
1.10 x 10";
1.30 x 10"^
-4
8.08 x 10 I
4.40 x 10";
5.19 x 10"4
a"Effective dose" is calculated by multiplying the beryllium concentration
in workplace by the factor (8/24) x (240/365) x (f/L).
For a given "effective" dose d and a relative risk R, the carcinogenic
potency is calculated by the formula B = (R-l) x 0.036/d where 0.036 is
the estimated lung cancer mortality rate in the U.S. population.
cancer potency estimates calculated under various assumptions about relative
risk estimates and levels of exposure. The potency estimates range from 1.10 x
10~4/(ng/m3) to 5.04 x 10~3/(ug/m3).
3
7.3.2.3 Risk Due to Exposure to 1 ug/m of Beryllium in Ail—Except for the
study on beryl ore (Wagner et al., 1969), all of the animal studies evaluated
in the present report produce considerably higher potency estimates than those
calculated on the basis of human data. A possible explanation is that a
specific beryllium compound (e.g., BeSO*) was used in animal experiments,
whereas workers were exposed to a combination of several forms of compounds.
If one adopts the most conservative approach, the upper-bound potency estimate
3
4.4/((jg/m ) would be used to represent the carcinogenic potential of beryllium.
This potency is estimated on the basis of data observed in an experiment in
which the level of exposure was very similar to the occupational exposure.
Thus, the high potency estimate is not simply due to the use of a particular
extrapolation model. The use of such a potency estimate would overestimate
7-65
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the human risk and is not consistent with the human experience in the beryllium
• **
industry. Therefore, the CAG recommends that the estimate of 7.4 x 10 /(pg/m )
be used as the carcinogenic potency of beryllium. This value is the geometric
mean of 12 potency estimates calculated on the basis of human data under
various assumptions. On this basis, the incremental risk associated with 1
|jg/m of beryllium in air is estimated to be 7.4 x 10 . This estimate could
be considered to be an upper-bound estimate of the cancer risk because low-dose
linearity is assumed in the extrapolation.
7.3.3 Comparison of Potency With Other Compounds
One of the uses of quantitative potency estimates is to compare the rela-
tive potencies of carcinogens. Figure 7-2 is a histogram representing the
frequency distribution of potency indices for 53 suspect carcinogens evaluated
by the CAG. The actual data summarized by the histogram are presented in
Table 7-14. The potency index used herein was derived from the carcinogenic
potency of the compound and is expressed in terms of (mMol/kg/day) . Where
no human data were available, animal oral studies were used in preference to
animal inhalation studies, since oral studies have constituted the majority of
animal studies.
To calculate the potency index, it is necessary to convert the potency
estimate 7.4 x 10~ /((jg/m ) into 2.6/(mg/kg/day), a potency estimate in a
different dose unit. The new potency estimate, 2.6/(mg/kg/day), is obtained
by dividing 7.4 x 10~V(|jg/m3) by a factor of (1 ug/m3) x (20 m3/day)/70 kg =
2.86 x 10 mg/kg/day, under the assumption that the volumetric air intake for
a 70-kg person is 20 m /day. The potency index for beryllium is 2 x 10 ,
calculated by multiplying the potency estimate, 2.6/mg/kg/day, and the molecular
weight of beryllium 9. This calculation places the relative potency of beryllium
in the lower part of the third quartile of the 53 suspect carcinogens evaluated
by the CAG.
The ranking of relative potency indices is subject to the uncertainties
involved in comparing a number of potency estimates for different chemicals
based on varying routes of exposure in different species, by means of data
from studies whose quality varies widely. All of the indices presented are
based on estimates of low-dose risk, using linear extrapolation from the
observational range. These indices may not be appropriate for the comparison
of potencies if linearity does not exist at the low-dose range, or if compari-
son is to be made at the high-dose range. If the latter is the case, then an
index other than the one calculated above may be more appropriate.
7-66
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4th 3rd 2nd W
QUART1LE QUARDL£ QUARTILE QUAR71LE
4x10** 2x10**
12345
LOG Of POTENCY INDEX
678
Figure 7-2. Histogram representing the frequency distribution of the potency
indices of 53 suspect carcinogens evaluated by the Carcinogen Assessment
Group.
7-67
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TABLE 7-14. RELATIVE CARCINOGENIC POTENCIES AMONG 53 CHEMICALS EVALUATED BY THE CARCINOGEN ASSESSMENT GROUP
AS SUSPECT HUMAN CARCINOGENS
Level
of evidence3
Compounds
Acrylonitrile
Aflatoxin B-^
Aldrin
•^ Allyl chloride
00 Arsenic
B[a]P
Benzene
Benzidene
Beryllium
Cadmium
Carbon tetrachloride
Chlordane
CAS Number
107-13-1
1162-65-8
309-00-2
" 7440-38-2
50-32-8
71-43-2
92-87-5
7440-41-7
7440-43-9
56-23-5
57-74-9
Humans
L
L
I
S
I
S
S
L
L
I
I
Animals
S
S
L
I
S
S
S
S
S
S
L
Grouping
based on
IARC
criteria
2A
2A
28
1
28
1
1
2A
2A
26
3
Slope
(mg/kg/day)-l
0.24(W)
2900
11.4
1.19x10-2
15(H)
11.5
5.2xlO-2(W)
234(W)
2.6
7.8(W)
1.30x10-!
1.61
Molecular
wei ght
53.1
312.3
369.4
76.5
149.8
252.3
78
184.2
9
112.4
153.8
409.8
Potency
index
1x10+1
9xlO+5
4x10+3
9x10-1
2x10+3
3x10+3
4x10°
4xlO+4
2x10+1
9x10+2
2x10+1
7x10+2
Order of
magnitude
index)
+1
+6
+4
0
+3
+3
+1
+5
+1
+3
+1
+3
aS = Sufficient evidence; L = Limited evidence; I = Inadequate evidence.
(continued on the following page)
-------
TABLE 7-14. (continued)
Compounds
Chlori nated ethanes
1,2-dichloroethane
hexachloroethane
Level
of evidence3
CAS Number
107-06-2
67-72-1
1,1,2,2-tetrachloroethane 79-34-5
1,1 ,2-trichloroethane
Chloroform
^ Chromium
1
CT*
S DDT
Dichlorobenzidine
1,1-dichloroethylene
Dieldrin
2,4-dinitrotoluene
Diphenylhydrazine
Epichlorohydrin
Bis(2-chloroethyl )ether
Bis(chloromethyl ) ether
79-00-5
67-66-3
7440-47-3
50-29-3
91-94-1
75-35-4
60-57-1
121-14-2
122-66-7
106-89-8
111-44-4
542-88-1
: — i 1 ' ' j. _ _i
Humans
I
I
I
I
I
S
I
I
I
I
I
I
I
I
S
Animals
S
L
L
L
S
S
S
S
L
S
S
S
S
S
S
Group! ng
based on
IARC
criteria
2B
3
3
3
2B
1
2B
26
3
2B
2B
2B
2B
2B
1
Slope
(mg/kg/day)-l
6.9x10-2
1.42x10-2
0.20
5.73x10-2
7x10-2
41(W)
0.34
1.69
1.47x10-1(1)
30.4
0.31
0.77
9.9xlO-3
1.14
9300(1)
Molecular
wei ght
98.9
236.7
167.9
133.4
119.4
100
354.5
253.1
97
380.9
182
180
92.5
143
115
Potency
index
7x10°
3x10°
3x10+1
8x10°
8x10°
4xlO+3
1x10+2
4x10+2
1x10+1
lxlO+4
6x10+1
1x10+2
9x10-1
2x10+2
lxlO+6
Order of
magnitude
(Iog10
index)
+ 1
0
+ 1
+ 1
+1
+4
+2
+3
+1
+4
+2
+2
0
+2
+6
(continued on the following page)
-------
TABLE 7-14. (continued)
Compounds
Ethylene dibromide (EDB)
Ethylene oxide
Heptachlor
Hexachlorobenzene
T4 Hexachlorobutadiene
Hexachlorocyclohexane
technical grade
alpha isomer
beta isomer
gamma isomer
Hexach 1 orodi benzodi oxi n
Methyl ene chloride
Nickel
Nitrosami nes
Dimethyl nitrosami ne
Diethylnitrosamine
Dibutylnitrosamine
CAS Number
106-93-4
75-21-8
76-44-8
118-74-1
87-68-3
319-84-6
319-85-7
58-89-9
34465-46-8
75-09-2
7440-02-0
62-75-9
55-18-5
924-16-3
Level
of evidence3
Humans
I
L
I
I
I
I
I
I
I
I
L
I
I
I
Animals
S
L
S
S
L
S
L
L
S
L
S
S
S
S
Grouping
based on
IARC
criteria
2B
2A
2B
2B
3
2B
3
28
2B
3
2A
2B
2B
2B
Slope Molecular
(mg/kg/day)-l weight
41
1.26(1)
3.37
1.67
7.75x10-2
4.75
11.12
1.84
1.33
6.2x10+3
6.3xlO-4
1.15(W)
25.9(not by qf)
43.5(not by qf)
5.43
187.9
44.1
373.3
284.4
261
290.9
290.9
290.9
290.9
391
84.9
58.7
74.1
102.1
158.2
Potency
index
8x10+3
6x10+1
1x10+3
5x10+2
2x10+1
1x10+3
3x10+3
5x10+2
4x10+2
2xlO+6
5x10-2
7x10+1
2xlO+5
4x10
9x10+2
Order of
magnitude
(Iog10
index)
+4
+2
+3
+3
+ 1
j
+3
+3 !
+3
+3
+6 I
!
+2
+3
+4
+3
(continued on the following page)
-------
TABLE 7-14. (continued)
Level
of evidence9
Compounds CAS Number Humans
N-nitrosopyrrolidi ne
N-nitroso-N-ethylurea
N-nitroso-N-methylurea
N-nitroso-diphenylamine
PCBs
Phenols
2,4,6-trichlorophenol
Tetrachlorodibenzo-
p-dioxin (TCDO)
Tetrachloroethylene
Toxaphene
Tri chloroethy lene
Vinyl chloride
930-55-2 I
759-73-9 I
684-93-5 I
86-30-6 I
1336-36-3 I
88-06-2 I
1746-01-6 I
127-18-4 I
8001-35-2 I
79-01-6 I
75-01-4 S
Animals
S
S
S
S
S
S
S
L
S
L
S
Grouping
based on
I ARC
criteria
2B
2B
2B
2B
2B
2B
2B
3
2B
3
1
Slope
(mg/kg/day)-1
2.13
32.9
302.6
4.92x10-3
4.34
1.99x10-2
1.56x10+5
3.5x10-2
1.13
1.9x10-2
1.75x10-2(1)
Molecular
weight
100.2
117.1
103.1
198
324
197.4
322
165.8
414
131.4
62.5
Potency
index
2x10+2
4xlO+3
3xlO+4
1x10°
1x10+3
4x10°
5xlO+7
6x10°
5x10+2
2.5x10°
1x10°
Order of
magnitude
(Iog10
index)
+2
+4
+4
0
+3
+1
+8
+ 1
+3
0
0
aS = Sufficient evidence; L = Limited evidence; I = Inadequate evidence.
Remarks:
1. Animal slopes are 95% upper-limit slopes based on the linearized multistage model. They are calculated based on
animal oral studies, except for those indicated by I (animal inhalation), W (human occupational exposure), and H
(human drinking water exposure). Human slopes are point estimates based on the linear nonthreshold model.
2. The potency index is a rounded-off slope in (mmol/kg/day)"1 and is calculated by multiplying the slopes in
(mg/kg/day)"! t>y tne molecular weight of the compound.
3. Not all of the carcinogenic potencies presented in this table represent the same degree of certainty. All are
subject to change as new evidence becomes available.
-------
7.3.4 Summary of Quantitative Assessment
Both animal and human data have been used to calculate the carcinogenic
potency of beryllium. Most of the animal studies conducted on beryllium are
not well documented, were conducted only at single dose levels, and did not
utilize control groups. In the present report, data from eight animal inhala-
tion studies have been used to calculate the upper bounds for the carcinogenic
potency of beryllium. The upper-bound potency estimates calculated on the
-33 3
basis of animal data range from 2.9 x 10 /(ug/m ) to 4.4/(ug/m ). The magni-
tude of potency appears to depend upon the beryllium compound used in the
experiment. Among the four beryllium compounds examined in the eight studies,
beryl ore is the least carcinogenically potent, while beryllium sulfate (BeSO.)
is the most potent. Except in the case of the beryl ore study (Wagner et al.,
1969), the potency values for beryllium that have been estimated on the basis
of animal studies are considerably greater than those estimated from human
data. A possible explanation is that a specific beryllium compound (e.g.,
BeSO.) was used in animal experiments, whereas workers were exposed to a
combination of several forms of compounds. If one adopts the most conservative
3
approach, the maximum potency estimate 4.4/(ug/m ) would be used to represent
the carcinogenic potential of beryllium. This potency is estimated on the
basis of data obtained in an experiment in which the level of exposure was
very similar to the occupational exposure condition. Thus, the high potency
estimate is not due to the use of a particular low-dose extrapolation model.
The use of such a potency estimate would clearly overestimate the human risk
and would be inconsistent with the human experience in the beryllium industry.
Data from two epidemiologic studies by Mancuso (1979) and Wagoner et al.
(1980), and the industrial hygiene reviews by NIOSH (1972) and Eisenbud and
Lisson (1983), have been used to calculate the cancer risk associated with
exposure to air contaminated with beryllium. Three relative risk estimates,
1.67, 1.79, and 2.23, reported in the two epidemiologic studies, have been
used by the CAG to calculate the carcinogenic potency of beryllium. Despite
the deficiencies in these studies, the use of these relative risk estimates in
the calculation is considered appropriate for the reason that, even if the
studies were negative, the upper-limit estimates for these relative risks
would have been approximately equal to the reported values. In recognition of
the greater uncertainty associated with the exposure estimation, four different
"effective" levels of exposure that reflect various uncertainties, along with
7-72
-------
three relative risk estimates, have been used in the present calculations. As
a result, 12 potency estimates have been calculated, ranging from 1.1 x
10 /((jg/m ) to 5.0 x 10 /(ug/m ), with the geometric mean of the twelve
estimates being 7.4 x 10 /((jg/m ). The incremental lifetime cancer risk
q
associated with 1 ug/m of beryllium in the air is thus estimated to be 7.4 x
-4
10 . This estimate could be considered an upper-bound estimate of the cancer
risk because low-dose linearity is assumed in the extrapolation. This calcu-
lation places the relative carcinogenic potency of beryllium in the lower part
of the third quartile of the 53 suspect carcinogens evaluated by the CAG.
7.4 SUMMARY
7.4.1 Qualitative Summary
Experimental beryllium carcinogenesis has been successfully induced by
intravenous or intramedullary injection of rabbits, and by inhalation exposure
or intratracheal injection of rats. The carcinogenic evidence for mice (intra-
venously injected), monkeys, and rabbits (intratracheally injected or exposed
via inhalation) is presently uncertain. Guinea pigs, and possibly hamsters,
are not susceptible to beryllium carcinogenesis. In rabbits, osteosarcomas
and chondrosarcomas have been induced. These tumors have been highly invasive
and shown to readily metastasize. These tumors have been judged to be histo-
logically similar to corresponding human tumors. In rats, pulmonary adenomas
and/or adenocarcinomas of questionable malignancy have been obtained, although
these studies are not well documented.
For the purposes of assessing the risks of human exposures to beryllium,
the animal evidence has limitations. Despite the fact that osteosarcomas in
rabbits were observed in multiple experiments, it is of limited value to
assessing human risks because of the artificiality of the intravenous route of
administration and the use of complex mixtures of beryllium (zinc beryllium
silicate).
Epidemiologic studies present equivocal conclusions on the carcinogenicity
of beryllium and beryllium compounds. Early studies (see IARC, 1972, 1980;
Bayliss et al., 1971; Bayliss and Lainhart, 1972) did not provide positive
evidence, but a few recent studies suggest an increased risk of lung cancer in
beryllium-exposed workers. Data presented by Wagoner et al. (1980) indicating
significant positive lung carcinogenesis in humans exposed to beryllium have
been questioned. In general, the absence of beryllium exposure levels and the
7-73
-------
lack of information on other possible confounding factors within the workplace
make a positive correlation between beryllium exposure and increased risk of
cancer difficult to substantiate. Epidemiologic evidence must therefore be
classified as "limited" to "inadequate" according to the IARC criteria for
determining carcinogenicity from human studies.
Beryllium at the cellular level (precise chemical species unknown) in-
creased the misincorporation of polydeoxyadenosylthymidine into microsomal DNA
(Luke et al., 1975) and substantially reduced the fidelity of in vitro DNA
transcription by single-base substitutions (Sirover and Loeb, 1976).
Dipaolo and Casto (1979) reported the transformation of cultured fetal
cells of the Syrian hamster.
Beryllium has been tested for its ability to cause gene mutations in
Salmonella typhimurium, Escherichia coli, yeast, and cultured mammalian cells;
chromosomal aberrations, sister chromatid exchanges in cultured human lymphocytes
and Syrian hamster embryo cells; DNA damage in Escherichia coli and unscheduled
DNA synthesis in rat hepatocytes.
Beryllium sulfate and beryllium chloride have been shown to be nonmutagenic
in bacterial and yeast gene mutation assays that have been tested. Gene
mutation studies in cultured mammalian cells, Chinese hamster V79 cells, and
Chinese hamster ovary (CHO) cells, on the other hand, have yielded a positive
mutagenic response for beryllium. Similarly, chromosomal aberration and
sister chromatid exchange studies in cultured human lymphocytes and Syrian
hamster embryo cells have also resulted in positive mutagenic responses of
beryllium. In DNA damage and repair assays, beryllium was negative in the p_o]_,
rat hepatocyte, and mitotic recombination assays but weakly positive in the
rec assay. Based on the information available, beryllium appears to have the
potential to cause mutations.
7.4.2 Quantitative Summary
Both animal and human data are used to estimate the carcinogenic potency
of beryllium. Most of the animal inhalation studies for beryllium are not
well documented, were conducted only at single dose levels, and did not utilize
control groups. In the present report, data from eight rat studies have been
used to estimate the upper bounds for the carcinogenic potency of beryllium.
The upper-bound potency estimates calculated on the basis of animal data range
from 2.9 x 10~3/(ug/m3) to 4.4/(ug/m3). The magnitude of potency appears to
depend on the beryllium compound used in the experiment. Among the four
7-74
-------
beryllium compounds examined in the eight studies, beryl ore is the least
carcinogenically potent while beryllium sulfate (BeSO,) is the most potent.
Except in the case of the beryl ore rat study (Wagner et al., 1969), the
potency values for beryllium that have been estimated on the basis of animal
studies are considerably greater than those estimated from human data.
In light of the human experience in the beryllium industry, the risk
estimates from animal data do not appear to be reasonable. Therefore, infor-
mation from epidemiologic studies by Mancuso (1979) and Wagoner et al. (1980)
and the industrial hygiene reviews by NIOSH (1972) and Eisenbud and Lisson
(1983) have been used to estimate the cancer risks associated with exposure to
air contaminated with beryllium. The upper-bound incremental lifetime cancer
3
risk associated with 1 ug/m of beryllium in air is estimated to be 7.4 x
10~4/(ug/m3).
Although there are deficiencies in the epidemiologic studies from which
the relative risk estimates are obtained, all of the relative risk estimates
have values of approximately 2. Even if all of the studies were negative, a
statistical upper-bound estimate of a relative risk would be about equal to
the reported value of approximately 2. A major uncertainty of the risk esti-
mate for beryllium comes from the derivation of exposure levels in the work-
place and the temporal effect of the patterns of exposure. To account for
these uncertainties, the "effective" exposure level of beryllium is derived in
several ways, and the geometric mean of different potency estimates thus
calculated is used to represent the carcinogenic potency of beryllium.
4 3
The upper-bound incremental unit risk of 7.4 x 10 /(ug/m ) places the
relative carcinogenic potency of beryllium in the third quartile of the 53
suspect carcinogens evaluated by the CAG.
7.5 CONCLUSIONS
Using the IARC approach (Appendix B) for classifying the weight-of-evidence
for carcinogen!city in experimental animals, there is "sufficient" evidence to
conclude that beryllium and beryllium compounds are carcinogenic in animals,
whereas the epidemiologic evidence for the carcinogenicity of beryllium is
"limited" to "inadequate" according to the IARC criteria (Appendix B).
The overall evidence for the carcinogenicity, using the IARC criteria
(Appendix B), places beryllium and beryllium compounds in the Group 2A or 2B
7-75
-------
category, meaning that beryllium is probably carcinogenic to humans under
inhalation exposure conditions.
The upper-bound incremental lifetime cancer risk for continuous inhalation
exposure at 1 ug beryllium/m is estimated to be 7.4 x 10 . This means that
the actual unit risk is not likely to be higher, but could be lower than 7.4 x
10~4. Also, this places beryllium in the lower part of the third quartile of
the 53 suspect carcinogens evaluated by the CAG.
7-76
-------
8. HUMAN HEALTH RISK ASSESSMENT FOR BERYLLIUM
8.1 AGGREGATE HUMAN INTAKE OF BERYLLIUM
The intake via ambient air can be estimated to be generally less than
3
20 ng/day, assuming that 20 m air is inhaled per day. This is a conservative
estimate since even in some of the larger industrial cities, average concentra-
3
tions generally do not exceed 0.2 ng/m . Small segments of the population
living near beryllium-processing plants may have higher exposure via ambient
3
air since concentrations in such areas may exceed 10 ng/m .
There is a lack of data on beryllium in drinking water. There is one
estimate of an average concentration of 0.2 ug/1. Assuming a daily intake of
2 1 of water, this would mean an intake of 0.4 (jg via water. Food normally
contains low concentrations of beryllium. The limited data available indicate
that the average concentration may be around 0.1 ug/kg fresh weight. Assuming
a daily intake of 1200 g of food, this results in a food intake of 0.12 pg/day.
Thus, intake via food and water is probably less than 1 ug/day. These estimates
are based on the data of Meehan and Smythe (1967). Reeves (1979), however,
has estimated, based upon the data of Petzow and Zorn (1974), that food and
water may account for intakes up to 20 (jg/day.
Regardless of the data base used, exposure via air will constitute only a
minor part of the total exposure. Absorption both from the lungs and from the
gut is assumed to be relatively small. An additional exposure source may be
smoking.
8.2 SIGNIFICANT HEALTH EFFECTS OF BERYLLIUM FOR HUMAN RISK ASSESSMENT
Acute noncarcinogenic effects of beryllium exposure have been exclusively
of concern in the workplace, and even with considerable reductions in occupa-
tional exposure to beryllium compounds, new cases still appear, indicating
that the handling of beryllium must be carefully controlled. The lung is the
critical organ of acute exposures and the acute lung effects generally are
regarded as reversible, even if, in a few cases, chronic beryllium disease
results, especially when further exposures occur.
Chronic effects after exposure to beryllium compounds have been reported
to occur both in occupational groups and in members of the general population
living in the vicinity of beryllium-emitting plants. In contrast to most
other metals, the lung effects caused by chronic exposure to beryllium may be
8-1
-------
combined with systemic effects, and one common factor may be hypersensitization.
Thus, no attempt is made to differentiate between risk estimates for local and
systemic effects after chronic exposure to beryllium via air. There are no
data that indicate that exposure via food or water can cause such systemic
reactions.
The epidemic of chronic beryllium disease which started in the 1940's as
a result of heavy exposure resulted in many deaths from chronic lung disease
and secondary heart disease (cor pulmonale) and probably also cancer of the
lung. Of special interest is that a large number of cases found in the Beryl-
lium Case Registry were "neighborhood" cases. These cases were people living
in the vicinity of beryllium-emitting industries, and the clinical manifestations
of their disease did not differ from that of occupationally exposed workers.
Within the last decades, no new neighborhood cases have been reported to the
registry.
It can be concluded that chronic lung disease is a critical effect for
exposure to beryllium compounds and preventing this effect will also prevent
other effects related to or combined with that condition.
Epidemiological studies present equivocal conclusions on the carcinogeni-
city of beryllium and beryllium compounds. Such studies have been subject to
numerous deficiencies including inadequate considerations of smoking effects
and previous exposures to other compounds, as well as underestimations of ex-
pected lung cancer deaths resulting in upward biases of relative risks. Never-
theless, the possibility exists that a portion of the excess cancer risks
reported in these studies may be due to beryllium exposure.
IARC has concluded that beryllium and its compounds should be classified
as "limited" with respect to the human epidemiologic evidence of carcinogenicity
and "sufficient" with respect to animal evidence. Overall, the weight of
evidence indicates that beryllium and beryllium compounds should be considered
as probably carcinogenic for humans.
8.3 DOSE-EFFECT AND DOSE-RESPONSE RELATIONSHIPS OF BERYLLIUM
An attempt has been made to quantify the health impact of beryllium on
human beings with reference to potential effects on the U.S. population as a
whole. Only chronic effects resulting from long-term low level exposure are
discussed, since there is no likelihood of acute effects in the general
population. Even though data are sparse on exposure via food and water, it
8-2
-------
seems very likely that exposure from such sources is very low and that subse-
quent absorption of beryllium from the intestinal tract is also very low.
Therefore, only effects from respiratory exposure are discussed below.
In contrast to some other agents, it is very difficult to use exposure
data to construct dose-response curves since the immunological component of
chronic beryllium disease indicates that, in addition to direct toxic effects
from beryllium in the lung, some people may be at extra risk for effects due
to hypersensitization. There is also a lack of data on internal indices of
exposure. Information on the levels of beryllium in tissues of the general
population is very sparse.
Nevertheless, data collected throughout the years on air concentrations
of beryllium in factories and on the occurrence of effects may be used to
determine an effect level (dose-response relationship). The standard set in
1949, 2 |jg/m for occupational exposure, can be used as a starting point.
When this standard has been exceeded, as reported by Kanarek et al. (1973) and
Sprince et al. (1978), clear effects have been noted with regard to pulmonary
changes and respiratory function. A drastic reduction of exposure can result
in some improvement in pulmonary function, but the data do not allow conclu-
sions about the no-effect level.
In the study by Cotes et al. (1983), the average exposure was stated to
be less than or equal to 2 ug/m . However, the data were presented as geomet-
ric means, and the arithmetic mean, which is a more appropriate estimate of
true exposure, might have been considerably higher. It is true that in several
areas studied by Cotes and co-workers, the geometric means were so low that
o
the arithmetic means must also have been well below 2 ug/m . Nevertheless, in
that same study, which was based on data collected during an 8-year period
with more than 3,000 measurements of beryllium in the air, there were also
3
several periods when peak exposures were above 100 {jg/m . It is thus quite
conceivable that, of the more than 100 workers studied in the factory, several
may have had relatively high exposures during shorter periods. A few cases of
verified or strongly suspected chronic beryllium disease were noticed in the
factory workers. However, no functional impairment could be found among the
workers, in contrast to the study by Kanarek et al., where exposures were much
greater. Only the X-ray findings were typical of beryllium exposure. It is
therefore reasonable to assume that in the Cotes et al. study, a "no observable
adverse effect level" (NOAEL) was found, indicating that the present occupational
3
standard of 2 ug/m seems to protect against noncarcinogenic toxic effects.
8-3
-------
In summary, it appears that it may be impossible to establish dose-response
relationships with regard to the noncarcinogenic effects of inhaled beryllium
because hypersensitization may occur at random. The present occupational
standard, which is far above present levels of beryllium in ambient air, seems
to be a reasonable safe level for preventing noncarcinogenic effects in
industry.
In Chapter 7, the Carcinogen Assessment Group (CAG) of the U.S. Environ-
mental Protection Agency has estimated carcinogenic unit risks for air exposure
to beryllium. The quantitative aspect of carcinogen risk assessment is in-
cluded here because it may be of use in setting regulatory priorities, evalua-
ting the adequacy of technology-based controls, and other aspects of the
regulatory decision-making process. However, the imprecision of presently
available technology for estimating cancer risks to humans at low levels of
exposure should be recognized. At best, the linear extrapolation model used
(see Section 7.3) provides a rough but plausible estimate of the upper limit
of risk—that is, with this model it is not likely that the true risk would be
much more than the estimated risk, but it could be considerably lower. The
risk estimates presented below should not be regarded, therefore, as accurate
representations of true cancer risks even when the exposures involved are
accurately defined. The estimates presented may, however, be factored into
regulatory decisions to the extent that the concept of upper-risk limits is
found to be useful.
Although there are many animal inhalation studies showing carcinogenic
effects from beryllium, the animal data do not appear to provide an adequate
data base for estimating the human cancer risk associated with exposure to
beryllium. Most of the animal studies that have been conducted on beryllium
are not well documented, were conducted only at single-dose levels, and did
not utilize control groups. In the present report, data from several of the
more reliable of these animal inhalation studies have been used to calculate
the upper bounds for the carcinogenic potency of beryllium. The upper-bound
_3
potency estimates calculated on the basis of animal data range from 2.9 x 10 /
3 3
(ug/m ) to 4.4/(ug/m ), depending on the beryllium compound used in the experi-
ment. Among the four beryllium compounds examined in the seven studies
referenced herein, the least carcinogenically potent was shown to be beryl ore,
while the most potent was beryllium sulfate (BeSCO. Except in the case of
the beryl ore study (Wagner et al. 1969), the potency values for beryllium that
8-4
-------
have been estimated on the basis of animal studies are considerably greater
than those estimated from human data. In light of the human experience in the
beryllium industries, the risk estimates from animal data do not appear to be
reasonable. Therefore, despite the deficiencies associated with the human
data, information from two epidemiologic studies by Mancuso (1979) and Wagoner
et al. (1980) and the industrial hygiene reviews by NIOSH (1972) and Eisenbud
and Lisson (1983) have been used to estimate the cancer risks associated with
exposure to air contaminated with beryllium. The upper-bound incremental
lifetime cancer risk associated with 1 pg/m of beryllium in the air is esti-
-4
mated to be 7.4 x 10 . This incremental unit risk estimate places the rela-
tive carcinogenic potency of beryllium in the lower part of the third quartile
of the 53 suspect carcinogens evaluated by the CAG.
8.4 POPULATIONS AT RISK
Populations at risk may be defined as those segments of the population
where there is an increased risk of effects from beryllium, either by virtue
of a special exposure status or by some physiological status that renders them
more susceptible to the effects of beryllium.
In terms of exposure, persons engaged in handling beryllium in occupational
environments obviously comprise individuals at highest risk. With regard to
the population at large, there may still be a small risk for people living
near beryllium-emitting industries. However, the risk for such individuals
may not be due so much to ambient air levels of beryllium, but rather due to
the possibility of accumulated beryllium-contaminated dust within the household.
There are no data that allow an estimate of the number of people that may be
at such risk, but it is reasonable to assume that it is a very small group.
It should be noted that no new "neighborhood" cases of beryllium disease have
been reported since the 1940's.
8-5
-------
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Andrews, J.L ; Kazemi, H.; Hardy, H.L. (1969) Patterns of lung dysfunction in
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trial Minerals; June 1980.
4
Araki, M. ; Okada, S. ; Fujita, M. (1954) Experimental studies on beryllium-
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Bayliss, D.L.; Wagoner, J.K. (1977) Bronchogenic cancer and cardiorespiratory
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9-1
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Belman, S. (1969) Beryllium binding of epidermal constituents. JOM J. Occup.
Med. 11: 175-183.
Bencko, V.; Brezina, M.; Banes, B.; Cikrt, M. (1979) Penetration of beryllium
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APPENDIX A
ANALYSIS OF INCIDENCE DATA WITH TIME-DEPENDENT DOSE PATTERN
Table A-l presents time-to-death data with or without lung tumors. These
data are reconstructed from Figure 1 in Reeves and Deitch (1969), in which
study animals were exposed to beryllium by inhalation at a concentration of
3
35 ng/m , 35 hours/week for specific durations during the 24-month observa-
tion period.
The computer program ADOLL1-83, developed by Crump and Howe (1984),
has been used to fit these data. Models with one to seven stages and with one
of the stages affected by the dose have been calculated. The model with the
maximum likelihood has been selected as the best-fitting model. The identified
best-fitting model has six stages, with the fifth stage dose-affected. Using
this model, the maximum likelihood estimate of the slope (linear component),
3
under the assumption of constant exposure, is 0.81/(ug/m ). The 95 percent
3
upper confidence limit for the slope is 1.05/(pg/m ).
A-l
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TABLE A-l. TIME-TO-DEATH DATA3
Exposure period Time-to-death
1. Control 19 , 20 (2), 21 (6), 22 (8), 24 (8)
2. 14th - 19th 14~(2), 15~, 20"(4), 20+, 2l"(5), 21+, 22~(5), 24~(3), 24+
month
3. llth - 16th 20~(2), 2l"(5), 21+, 22~, 22+(3), 24+(9)
month
4. 8th - 13th 13" 14", 20+(2), 2l"(5), 21+, 22+(6), 23~(2), 24~(4),
month 24 (3)
5. 5th - 10th 13" 19~(3), 20+(3), 2l"(2), 21+(4), 22~, 22+(4), 23~,
month 24 (3)
6. 2nd - 8th 16" 17", 18", 19~(4), 20~(2), 20+, 21~(3), 21+(3), 22~,
month 22 (6), 24
7. 8th - 19th 15~(2), 17~ 19~, 20~(3), 2l"(5), 21+(3), 22~(3), 22+(2),
month 24 (2), 24 (4)
8. 2nd - 13th 14", 18", 19~(4), 20+(3), 21+(6), 22+(4), 24+(2)
month
9. 2nd - 19th 16", 18"(4), 19~(2), 20"(5), 20+(3), 21+(3), 21~, 22+
month
t and t indicate, respectively, the time-to-death with and without
lung tumor; n is the number of replications.
i Q
All animals were exposed to beryllium at a concentration of 35 (jg/m , 35
hours/week.
A-2
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APPENDIX B
INTERNATIONAL AGENCY FOR RESEARCH ON CANCER CRITERIA FOR
EVALUATION OF THE CARCINOGENICITY OF CHEMICALS*
ASSESSMENT OF EVIDENCE FOR CARCINOGENICITY FROM STUDIES IN HUMANS
Evidence of carcinogenicity from human studies comes from three main
sources:
1. Case reports of individual cancer patients who were exposed to the
chemical or process.
2. Descriptive epidemiological studies in which the incidence of cancer
in human populations was found to vary in space or time with exposure to the
agents.
3. Analytical epidemiological (case-control and cohort) studies in
which individual exposure to the chemical or group of chemicals was found to
be associated with an increased risk of cancer.
Three criteria must be met before a causal association can be inferred
between exposure and cancer in humans:
1. There is no identified bias which could explain the association.
2. The possibility of confounding has been considered and ruled out as
explaining the association.
3. The association is unlikely to be due to chance.
In general, although a single study may be indicative of a cause-effect
relationship, confidence in inferring a causal association is increased when
several independent studies are concordant in showing the association, when
the association is strong, when there is a dose-response relationship, or when
a reduction in exposure is followed by a reduction in the incidence of cancer.
The degrees of evidence for carcinogenicity from studies in humans are
categorized as:
I. Sufficient evidence of carcinogenicity, which indicates that there is
a causal relationship between the agent and human cancer.
^Adapted from International Agency for Research on Cancer Monographs
Supplement 4, Evaluation of the Carcinogenic Risk of Chemicals to Humans,
1982, pp. 11-14.
B-l
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2. Limited evidence of carcinogenicity, which indicates that a causal
interpretation is credible, but that alternative explanations, such as chance,
bias, or confounding, could not adequately be excluded.
3. Inadequate evidence, which indicates that one of three conditions
prevailed: (a) there were few pertinent data; (b) the available studies,
while showing evidence of association, did not exclude chance, bias, or con-
founding; (c) studies were available which do not show evidence of carcino-
genicity.
ASSESSMENT OF EVIDENCE FOR CARCINOGENICITY FROM STUDIES IN EXPERIMENTAL ANIMALS
These assessments are classified into four groups:
1. Sufficient evidence of carcinogenicity, which indicates that there is
an increased incidence of malignant tumors: (a) in multiple species or strains;
or (b) in multiple experiments (preferably with different routes of administra-
tion or using different dose levels); or (c) to an unusual degree with regard
to incidence, site or type of tumor, or age at onset. Additional evidence may
be provided by data on dose-response effects, as well as information from
short-term tests or on chemical structure.
2. Limited evidence of carcinogenicity, which means that the data sug-
gest a carcinogenic effect but are limited because: (a) the studies involve a
single species, strain, or experiment; or (b) the experiments are restricted
by inadequate dosage levels, inadequate duration of exposure to the agent,
inadequate period of follow-up, poor survival, too few animals, or inadequate
reporting; or (c) the neoplasms produced often occur spontaneously and, in the
past, have been difficult to classify as malignant by histological criteria
alone (e.g., lung and liver tumors in mice).
3. Inadequate evidence, which indicates that because of major qualita-
tive or quantitative limitations, the studies cannot be interpreted as showing
either the presence or absence of a carcinogenic effect; or that within the
limits of the tests used, the chemical is not carcinogenic. The number of
negative studies is small, since, in general, studies that show no effect are
less likely to be published than those suggesting carcinogenicity.
4. No data indicate that data were not available to the Working Group.
The categories, sufficient evidence and limited evidence, refer only to
the strength of the experimental evidence that these chemicals are carcinogenic
and not to the extent of their carcinogenic activity nor to the mechanism
involved. The classification of any chemical may change as new information
becomes available.
B-2
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EVALUATION OF CARCINOGENIC RISK TO HUMANS
At present, no objective criteria exist to interpret data from studies in
experimental animals or from short-term tests directly in terms of human risk.
Thus, in the absence of sufficient evidence from human studies, evaluation of
the carcinogenic risk to humans was based on consideration of both the epide-
miological and experimental evidence. The breadth of the categories of evi-
dence defined above allows substantial variation within each. The decisions
reached by the Working Group regarding overall risk incorporated these diffe-
rences, even though they could not always be reflected adequately in the
placement of an exposure into a particular category.
The chemicals, groups of chemicals, industrial processes, or occupational
exposures were thus put into one of three groups:
Group 1
The chemical, group of chemicals, industrial process, or occupational
exposure is carcinogenic to humans. This category was used only when there
was sufficient evidence from epidemiological studies to support a causal
association between the exposure and cancer.
Group 2
The chemical, group of chemicals, industrial process, or occupational
exposure is probably carcinogenic to humans. This category includes exposures
for which, at one extreme, the evidence of human carcinogenicity is almost
"sufficient," as well as exposures for which, at the other extreme, it is
inadequate. To reflect this range, the category was divided into higher
(Group A) and lower (Group B) degrees of evidence. Usually, category 2A was
reserved for exposures for which there was at least limited evidence of car-
cinogenicity to humans. The data from studies in experimental animals played
an important role in assigning studies to category 2, and particularly those
in Group B; thus, the combination of sufficient evidence in animals and inade-
quate data in humans usually resulted in a classification of 2B.
In some cases, the Working Group considered that the known chemical
properties of a compound and the results from short-term tests allowed its
transfer from Group 3 to 2B or from Group 2B to 2A.
Group 3 I
The chemical, group of chemicals, industrial process, or occupational
exposure cannot be classified as to its carcinogenicity to humans.
B-3
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