?xEPA
United States
Environmental Protection
Agency
Office of Health and
Environmental Assessment
Washington DC 20460
EPA-600/8-84-015A
April 1984
External Review Draft
Research and Development
Health Assessment
Document for
Chlorinated
Benzenes
Part 1 of 2
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(Do Not
Cite or Quote)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.
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EPA-600/8-84-015A
April 1984
External Review Draft
DRAFT
Do not cite or quote
HEALTH ASSESSMENT DOCUMENT
FOR
CHLORINATED BENZENES
Part 1 of 2
Notice
This document 1s a preliminary draft. It has not been
formally released by EPA and should not at this stage be
construed to represent Agency policy. It 1s being circu-
lated for comment on Us technical accuracy and policy Im-
plications.
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Office of Health and Environmental Assessment
Envirinmental Criteria and Assessment Office
Cincinnati , Ohio *»5268
Project Manager: W. Bruce Pelrano
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DISCLAIMER
This report 1s 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.
NOTE
For Information concerning this document, please contact the project
manager, W. Bruce Pelrano (513/684-7573) of the Environmental Criteria and
Assessment Office, Cincinnati, OH 45268.
11
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PREFACE
The Office of Health and Environmental Assessment of the Office of
Research and Development has prepared this Health Assessment Document (HAD)
on chlorinated benzenes at the request of the Office of A1r Quality, Plan-
ning and Standards. The chlorinated benzenes are a group of 12 chlorinated
cyclic aromatic compounds which are currently being studied by the Environ-
mental Protection Agency (EPA) to determine 1f they should be regulated as
hazardous air pollutants under the Clean A1r Act.
In the development of this assessment document, the scientific litera-
ture has been searched and Inventoried, key studies have been reviewed and
evaluated and summaries and conclusions have been directed at Identifying
the health effects from exposure to the various chlorinated benzenes. At
several stages 1n the HAD development process, the chlorinated benzenes
document has been reviewed for scientific and technical accuracy. These
peer reviews have been by scientists from Inside and outside the EPA.
Observed effect levels and dose-response relationships are discussed where
appropriate 1n order to Identify the critical effect and to place adverse
health responses 1n perspective with observed environmental levels.
111
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AUTHORS, CONTRIBUTORS, AND REVIEWERS
The EPA Office of Health and Environmental Assessment (OHEA) was responsible
for the preparation of this draft health assessment document. The OHEA
Environmental Criteria and Assessment Office (ECAO-Cincinnati) had overall
responsibility for coordination and direction of the document preparation and
production effort (W. Bruce Peirano, Project Manager, Jerry F. Stara, Director,
ECAO-Cincinnati).
The participating members of the Environmental Criteria and Assessment
Office-Cincinnati, Ohio are:
W. Bruce Peirano, M.S.*
L. Erdreich, Ph.D.
H. Ball, M.S
C. DeRosa, Ph.D.
R. Hertzberg, Ph.D.
J. Risher, M.S.
S. Lutkerihoff, B.S.
D. Mukerjee, M.Sc., Ph.D.
J. Orme, M.S.
J. F. Stara, D.V.M.; D.S., Director
D. Reisman, M.En.
R. Bruins, M.S.
W. Pepelko, Ph.D.
C. Mullin, M. En.
F. Mink, Ph.D.
M. Dourson, Ph.D.
B. Farren, B.S.
D. Basu, Ph.D., Syracuse Research Corp.*
M. Neal, Ph.D., Syracuse Research Corp.*
S. Que Hee, Ph.D., Univ. of Cincinnati *
The OHEA Carcinogen Assessment Group (CAG) was responsible for preparation
of the sections on carcinogenicity. Participating members of the CAG are listed
below:
Roy E. Albert, M.D. (Chairman)
Elizabeth L. Anderson, Ph.D.
Larry D. Anderson, Ph.D.
Steven Bayard, Ph.D.
David L. Bayliss, M.S.
Chao W. Chen, Ph.D.*
Herman J. Gibb, B.S., M.P.H.
Bernard H. Haberman, D.V.M., M.S.
Charalingayya B. Hiremath, Ph.D.
James W. Holder, Ph.D.
Robert E. McGaughy, Ph.D.*
Jean C. Parker, Ph.D.
Dharm V. Singh, D.V.M., Ph.D.
Todd W. Thorslund, Sc.D.
Muriel M. Lippman, Ph.D. (Consultant)*
The OHEA Reproductive Effects Assessment Group (REAG) was responsible for
the preparation of the sections on mutagenicity. Participating members of
the REAG are listed below:
John R. Fowle III, Ph.D.
Ernest R. Jackson, M.S.
David Jacobson-Kram, Ph.D.
Casey Jason, M.D.
K. S. Lavappa, Ph.D.
Sheila L. Rosenthal, Ph.D.*
Carol N. Sakai, Ph.D.
Vicki Vaughan-Dellarco, Ph.D.
Peter E. Voytek, Ph.D. (Director)
Authors
i v
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The following people also contributed to the development of this
document:
David Dellarco EPA Office of Toxic Substances
Linda S. Erdreich ECAO-Cincinnati
Charles H. Nauman OHEA Exposure Assessment Group
David J. Reisman ECAO-Cincinnati
Phil Wirdzek EPA Office of Toxic Substances
The following individuals were asked to review earlier drafts of this
document:
George T. Bryan University of Wisconsin
Derek J. Cripps University of Wisconsin
Erma Durden ECAO-Cincinnati
Erdogan Erturk University of Wisconsin
Richard W. Lambrecht University of Wisconsin
Carl R. Morris EPA Office of Toxic Substances
Henry A. Peters University of Wisconsin
James Withey Food Directorate, Canada
The following members of the ECAO-Cincinnati Technical Services Staff
were responsible for document production:
Cynthia Cooper Karen Mann
Patricia Daunt Judith Olsen
Cindy Fessler Bette Zwayer
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CHLORINATED BENZENES PEER REVIEW PANEL MEMBERS
July 25-26, 1983 Cincinnati, Ohio
Chairman:
W. Bruce Pelrano, ECAO-CIN
Julian B. Andelman
D1pak Basu
Gary P. Carlson
Herbert H. Cornish
Fred Coulston
Diane Courtney
David Dellarco
Chris DeRosa
Chris Dlppel
Linda S. Erdrelch
Charlie Hlremath
Muriel M. Llppman
Debdas Mukerjee
Albert Munson
Chuck H. Nauman
Mike Neal
William E. Pepelko
Shane Que Hee
Martha J. Radlke
David J. Relsman
John F. Rlsher
Sheila L. Rosenthal
Jerry F. Stara
Norman M. Trieff
Phil Wirdzek
Members
University of Pittsburgh
Syracuse Research Corporation
Purdue University
University of Michigan
Coulston International Corporation
EPA, HERL-RTP
EPA, OTS, Washington, DC
University of Maine
Dynamac Corporation
EPA, ECAO-CIN
EPA, CAG, Washington, DC
ERNACO, Inc.
EPA, ECAO-CIN
Medical College of Virginia
EPA, EAG, Washington, DC
Syracuse Research Corporation
EPA, ECAO-CIN
University of Cincinnati College of Medicine
University of Cincinnati College of Medicine
EPA, ECAO-CIN
EPA, ECAO-CIN
EPA, REAG, Washington, DC
EPA, ECAO-CIN
University of Texas Medical Branch
EPA, OTS, Washington, DC
V I
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TABLE OF CONTENTS
1. INTRODUCTION 1-1
2. SUMMARY AND CONCLUSIONS 2-1
2.1. SUMMARY 2-1
2.1.1. Properties, Production and Use - 2-1
2.1.2. Environmental Levels, Transport and Fate 2-2
2.1.3. Ecological Effects 2-4
2.1.4. Pharmacoklnetlcs 2-5
2.1.5. Effects on Humans 2-10
2.1.6. Mammalian Toxicology 2-12
2.2. CONCLUSIONS 2-20
2.3. NEEDS FOR FUTURE RESEARCH 2-20
3. PHYSICAL AND CHEMICAL PROPERTIES/ANALYTICAL METHODOLOGY 3-1
3.1. SYNONYMS, TRADE NAMES AND IDENTIFICATION NUMBERS 3-1
3.2. PHYSICAL AND CHEMICAL PROPERTIES 3-1
3.3. ANALYTICAL METHODOLOGY 3-15
3.3.1. Chemical Analysis 1n A1r 3-15
3.3.2. Chemical Analysis 1n Water 3-18
3.3.3. Chemical Analysis 1n Soil, Sediment and Chemical
Waste Disposal Site Samples 3-19
3.3.4. Chemical Analysis 1n F1sh and Other Foods 3-20
3.4. SUMMARY 3-23
4. PRODUCTION, USE AND ENVIRONMENTAL LEVELS 4-1
4.1. PRODUCTION 4-1
4.2. USE 4-5
4.3. SOURCE AND ENVIRONMENTAL LEVELS 4-5
4.3.1. Levels in A1r 4-12
4.3.2. Water 4-18
4.3.3. Food 4-26
4.3.4. Soil and Sediments 4-28
4.3.5. Human Tissue Residues 4-29
4.4. RELATIVE SOURCE CONTRIBUTIONS TO TOTAL EXPOSURE 4-34
4.4.1. A1r 4-36
4.4.2. Water 4-36
4.4.3. Food 4-38
4.5. SUMMARY 4-38
v i i
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Page
5. ENVIRONMENTAL TRANSPORT AND FATE 5-1
5.1. TRANSPORT 5_1
5.1.1. A1r 5-1
5.1.2. Water 5-2
5.1.3. Soil 54
5.2. FATE 5-7
5.2.1. A1r 5-7
5.2.2. Water 5-8
5.2.3. Soil 5-10
5.3. BIOCONCENTRATION, BIOACCUMULATION AND BIOMAGNIFICATION. . . 5-13
5.4. SUMMARY 5-19
6. ECOLOGICAL EFFECTS 6-1
6.1. EFFECTS ON THE AQUATIC ENVIRONMENT 6-1
6.1.1. Effect on Freshwater and Marine F1sh 6-1
6.1.2. Effect on Aquatic Crustaceans 6-14
6.1.3. Embryotoxlc and Reproductive Effects 6-16
6.1.4. Effect on Aquatic Plants 6-24
6.1.5. Residues 6-30
6.2. EFFECTS ON NONAQUATIC ENVIRONMENTS 6-34
6.2.1. Plants 6-34
6.2.2. Insects 6-35
6.2.3. Birds 6-37
6.2.4. Residues 6-38
6.3. SUMMARY 6-39
7. MONOCHLOROBENZENE 7-1
7.1. PHARMACOKINETICS 7-1
7. .1. Absorption 7-1
7. .2. Distribution 7-1
7. .3. Metabolism 7-2
7. .4. Excretion 7-5
7. .5. Summary 7-10
7.2. EFFECTS ON HUMANS 7-10
v i i i
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Page
7.3. MAMMALIAN TOXICITY 7-12
7.3.1. Acute ToxIcHy 7-12
7.3.2. Subchronlc ToxIcHy 7-15
7.3.3. Chronic ToxIcHy 7-23
7.3.4. MutagenlcHy 7-24
7.3.5. Carc1nogen1c1ty 7-24
7.3.6. Reproductive and Teratogenlc ToxIcHy 7-31
7.4. INTERACTIONS 7-31
7.5. SUMMARY 7-32
8. DICHLOROBENZENES 8-1
8.1. PHARMACOKINETICS 8-1
8.1.1. Absorption 8-1
8.1.2. Distribution 8-3
8.1.3. Metabolism 8-6
8.1.4. Excretion 8-8
8.1.5. Summary 8-9
8.2. EFFECTS ON HUMANS 8-10
8.2.1. Occupational Studies 8-10
8.2.2. Case Studies 8-11
8.2.3. Summary 8-17
8.3. MAMMALIAN TOXICOLOGY 8-17
8.3.1. Acute ToxIcHy 8-17
8.3.2. Subchronlc ToxIcHy 8-22
8.3.3. Chronic ToxIcHy 8-32
8.3.4. MutagenlcHy 8-33
8.3.5. CardnogenlcHy 8-34
8.3.6. Reproductive and Teratogenlc ToxIcHy 8-39
8.4. INTERACTIONS 8-39
8.5. SUMMARY 8-40
9. TRICHLOROBENZENES 9-1
9.1. PHARMACOKINETICS 9-1
9.1.1. Absorption 9-1
9.1.2. Distribution 9-2
9.1.3. Metabolism 9-2
9.1.4. Excretion 9-6
9.1.5. Summary 9-8
9.2. EFFECTS IN HUMANS 9-9
i x
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Page
9.3. MAMMALIAN TOXICOLOGY 9-9
9.3.1. Acute Tox1c1ty 9-9
9.3.2. Subchronlc Tox1c1ty 9-14
9.3.3. Chronic Tox1c1ty 9-23
9.3.4. MutagenUUy 9-24
9.3.5. Carc1nogen1c1ty 9-25
9.3.6. Reproductive and Teratogenlc Toxldty 9-26
9.4. INTERACTIONS 9-28
9.5. SUMMARY 9-28
10. TETRACHLOROBENZENES 10-1
10.1. PHARMACOKINETICS 10-1
10.1.1. Absorption 10-1
10.1.2. Distribution 10-2
10.1.3. Metabolism 10-7
10.1.4. Excretion 10-10
10.1.5. Summary 10-13
10.2. EFFECTS ON HUMANS 10-14
10.3. MAMMALIAN TOXICOLOGY 10-15
10.3.1. Acute Toxldty 10-15
10.3.2. Subchronlc Toxldty 10-20
10.3.3. Chronic Toxldty 10-22
10.3.4. Mutagenldty 10-22
10.3.5. Cardnogenldty 10-23
10.3.6. Reproductive and Teratogenlc Effects 10-23
10.4. INTERACTIONS 10-24
10.5. SUMMARY 10-24
11. PENTACHLOROBENZENE 11-1
11.1. PHARMACOKINETICS 11-1
11.1.1. Absorption 11-1
11.1.2. Distribution 11-2
11.1.3. Metabolism 11-7
11.1.4. Excretion . 11-11
11.1.5. Summary . 11-13
11.2. EFFECTS ON HUMANS 11-13
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11.3. MAMMALIAN TOXICOLOGY 11-13
11.3.1. Acute Tox1c1ty 11-13
11.3.2. SubchronU ToxIcHy 11-16
11.3.3. Chronic ToxIcHy 11-18
11.3.4. MutagenlcHy 11-19
11.3.5. CardnogenlcHy 11-19
11.3.6. Reproductive and Teratogenlc ToxIcHy 11-19
11.4. INTERACTIONS 11-26
11.5. SUMMARY 11-26
12. HEXACHLOROBENZENE 12-1
12.1. PHARMACOKINETICS 12-1
12.1.1. Absorption 12-1
12.1.2. Distribution 12-3
12.1.3. Metabolism 12-16
12.1.4. Excretion 12-20
12.1.5. Summary 12-27
12.2. EFFECTS ON HUMANS 12-29
12.2.1. Ep1dem1olog1c Studies 12-29
12.2.2. Accidental Ingestlon 1n Turkey 12-32
12.2.3. Summary 12-37
12.3 MAMMALIAN TOXICOLOGY 12-40
12.3.1. Acute ToxIcHy 12-40
12.3.2. SubchronU ToxIcHy 12-42
12.3.3. Chronic ToxIcHy 12-56
12.3.4. MutagenlcHy 12-59
12.3.5. Carc1nogen1c1ty 12-60
12.3.6. Reproductive and Teratogenlc Effects 12-125
12.4. INTERACTIONS 12-131
12.5. SUMMARY 12-134
13. OVERVIEW OF EFFECTS OF MAJOR CONCERN 13-1
13.1. PRINCIPAL EFFECTS AND TARGET ORGANS 13-1
13.2. ANIMAL TOXICITY STUDIES MOST USEFUL FOR HEALTH
ASSESSMENT AND ESTIMATED TOXICITY THRESHOLDS 13-5
13.2.1. Animal ToxIcHy Studies 13-5
13.2.2. Estimated ToxIcHy Thresholds 13-31
13.3. CARCINOGENICITY STUDIES 13-31
13.4. HUMAN STUDIES 13-39
XI
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Page
13.5. FACTORS INFLUENCING HEALTH HAZARD ASSESSMENT 13-40
13.5.1. Exposure 13-40
13.6. REGULATIONS AND STANDARDS 13-45
13.6.1. Occupational Standards 13-45
13.6.2. Transportation Regulations 13-51
13.6.3. Solid Waste Regulations 13-52
13.6.4. Food Tolerances 13-54
13.6.5. Water Regulations 13-54
13.6.6. A1r Regulations 13-55
14. REFERENCES 14-1
APPENDIX A: Comparison Among Different Extrapolation Models A-l
XI I
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LIST OF TABLES
No. Title Page
3-1 Synonyms, Trade Names and Identification Numbers of the
Chlorinated Benzenes 3-3
3-2 Physical Properties of the Chlorinated Benzenes 3-7
3-3 Vapor Pressures and Vapor Densities of the Chlorinated
Benzenes 3-8
3-4 Reported Composition of Commercial 1,2-D1chlorobenzene. . . . 3-11
4-1 United States Production of Chlorinated Benzenes for
Selected Years 4-2
4-2 U.S. Producers and Estimated Annual Production Capacities
(1983) of Chlorobenzenes. 4-6
4-3 A Summary of the Uses of the Chlorinated Benzenes 4-8
4-4 Estimated Quantities of Chlorobenzenes Lost During
Manufacture, and to the Environment Compared with
Total Production 1n 1983 4-9
4-5 Estimated Quantities of Hexachlorobenzene (HCB) 1n
Industrial Wastes and Byproducts in 1972 4-11
4-6 Chlorinated Benzene Levels 1n Ambient A1r from
Different Locations 1n the U.S. 4-13
4-7 Concentrations of Chlorinated Benzenes at Three Sites .... 4-16
4-8 Overall and Site-Specific Mean Atmospheric Levels of
Chlorobenzenes throughout the United States 4-17
4-9 Atmospheric Levels of Hexachlorobenzene Around Selected
Industrial Plants 4-19
4-10 Chlorinated Benzenes 1n Surface Water 4-20
4-11 Chlorobenzene Concentrations 1n Drinking Water from
Ontario, Canada 4-24
4-12 Frequency and Range of Concentrations of Chlorinated
Benzenes Pollutants 1n Industrial Wastewaters 4-27
4-13 Chlorinated Benzene Residues 1n Human Adipose Tissue 4-30
4-14 Chlorinated Benzenes 1n the Blood of Nine Residents of
Love Canal 1n Niagara Falls, New York 4-33
XI I I
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No. Title Page
4-15 Chlorinated Benzenes 1n the Breath and Urine of Nine
Residents of Love Canal 1n Niagara Falls, New York. ..... 4-35
4-16 Estimated Yearly Exposure to Several Chlorinated Benzenes
Via Inhalation 4-37
5-1 Predicted Transport and Fate of Chlorinated Benzenes
Released from Landfills and Lagoons 5-5
5-2 Transport of Chlorinated Benzenes 1n Sandy Soil 5-6
5-3 Estimated Atmospheric Residence Time and Dally Loss Rates
for Several Chlorinated Benzenes. 5-9
5-4 Aqueous B1odegradab1l1ty Studies of Chlorinated Benzenes. . . 5-11
5-5 Octanol/Water Partition Coefficients, B1oconcentrat1on
Factors and Biological Half-lives for Chlorinated Benzenes
1n F1sh 5-15
5-6 Bloconcentratlon Factor and Slope of the Elimination Curve
for Gupples (Poedlla retlculata) Exposed to Six Chlorinated
Benzenes 5-18
6-1 Acute Toxldty Data for F1sh Species Exposed to Chlorinated
Benzenes. ... ..... 6-2
6-2 Chronic Toxldty Values of Chlorinated Benzenes 1n F1sh . . . 6-12
6-3 Bloconcentratlon Factors of Some Chlorinated Benzenes
In Two F1sh Species 6-15
6-4 Acute Toxldty Data for Crustaceans Exposed to Chlorinated
Benzenes 6-17
6-5 Embryo-Larval Toxldty of Monochlorobenzene to Goldfish,
Largemouth Bass and Rainbow Trout 1n Soft and Hard Water. . . 6-21
6-6 Results of 1,2,4,5-Tetrachlorobenzene Tests with Embryo
to Juvenile Sheepshead Minnows 1n Continuous-Flow Natural
Seawater 6-23
6-7 Adult Llfespan and Reproductive Performance of Brine
Shrimp Exposed to 1,3,5-Tr1chlorobenzene 6-25
6-8 Acute Toxldty Data for Aquatic Algae Exposed to
Chlorinated Benzenes 6-26
6-9 Chlorinated Benzene Concentrations (jjg/8.) 1n Water and
Sediment 6-31
X I V
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No.
6-10
6-11
6-12
7-1
7-2
7-3
7-4
7-5
7-6
7-7
8-1
8-2
8-3
8-4
8-5
8-6
8-7
8-8
9-1
9-2
Title
Chlorinated Benzene Concentrations 1n a Variety of Marine
Species . . .
Emergence of Adult HousefHes 8 Days Following Exposure of
Pupae to "Saturation Concentration" of Dlchlorobenzene
Vapors
Chlorinated Benzene Residues 1n Bird Eggs
Percentage of Isomers of Chlorophenol from Metabolism
of Monochlorobenzene
Species Variation 1n Urinary Metabolites of 14C-Mono-
chlorobenzene
Acute Toxldty of Monochlorobenzene
Summary of Subchronlc Toxldty Studies on Monochlorobenzene .
Mutagen1c1ty Testing of Monochlorobenzene
Nonneoplastlc Lesions In F344 Rats Given Chlorobenzene by
Gavage for 2 Years
Statistical Comparisons of Liver Tumors 1n Male Rats
Treated with Chlorobenzene and Vehicle Controls . .
Tissue Concentrations of 1 ,4-D1chlorobenzene 1n Adult
Female CFY Rats
Chromosomal Alterations 1n Persons Accidentally Exposed
to 1 ,2-D1chlorobenzene
Case Reports Involving Dlchlorobenzenes (DCB)
Acute Toxldty of 1 ,2-01chlorobenzene
Acute Toxldty of 1 ,4-D1chlorobenzene ,
Subchronlc Toxlclty of l,2-D1chlorobenzene
Subchronlc Toxldty of 1 ,4-01chlorobenzene
NTP Bloassay of 1 ,2-D1chlorobenzene Analysis of
Primary Tumors 1n Male Rats: Adrenal Pheochromocytomas. . . .
Distribution of 14C-Labeled 1 ,2,4-Tdchlorobenzene 1n Rat
Tissues after Oral Dosing with 181.5 mg/kg/day for 7 Days . .
Summary of Subchronlc and Chronic Toxldty Studies
on Tdchlorobenzenes
Paqe
6-32
6-36
6-40
7-4
7-9
7-14
7-16
7-25
7-28
7-29
8-5
8-12
8-13
8-19
8-20
8-23
8-25
8-36
9-3
9-15
XV
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No. Title Page
10-1 Percentage of 1,2,4,5-Tetrachlorobenzene Steady-State
Reached at Specific Times 1n Fat and Plasma of Dogs 10 4
10-2 Time Required to Reach Various Percentages of 1,2,4,5-
Tetrachlorobenzene Steady-State 1n Fat and Plasma of Dogs . . 10-5
10-3 Unchanged Tetrachlorobenzene 1n Rabbit Tissues 6 Days
After Oral Dosing 10-6
10-4 Urinary Metabolites of Tetrachlorobenzene Isomers 1n
Rabbits 6 Days After Oral Dosing 10-9
10-5 Summary of Excretion of the IsomeMc Tetrachlorobenzenes
as Metabolites or as Unchanged Compound 1n Rabbits Dosed
Orally 10-11
10-6 Excretion of Unchanged Tetrachlorobenzenes 1n the Expired
A1r of Rabbits After Oral Dosing 10-12
10-7 Frequency of Chromat1d-type Chromosome Aberrations In
Peripheral Lymphocytes 10-16
10-8 Frequency of Labile Chromosome-type Aberrations 10-17
10-9 Frequency of Stable Chromosome-type Aberrations 10-18
10-10 Summary of Toxldty Studies on Tetrachlorobenzenes. ..... 10-19
11-1 Distribution of Pentachlorobenzene Residues 1n the
Tissues of Maternal Rats after Oral Administration 11-3
11-2 Distribution of Pentachlorobenzene Residues 1n the
Tissues of Fetal Rats after Oral Administration to Dams . . . 11-4
11-3 Distribution of Pentachlorobenzene and/or Metabolites on
the 40th Day 1n the Rhesus Monkey Following a Single Oral
Dose of 0.5 mg/kg Body Weight 11-6
11-4 Distribution of Pentachlorobenzene 1n Chinchilla Doe
Rabbits Expressed as a Percentage of Administered Dose. . . . 11-8
11-5 Percentage of Pentachlorobenzene and Its Metabolites
Identified 1n Urine, Feces and Various Organs of Rhesus
Monkeys Dosed 0.5 mg/kg Body Weight Pentachlorobenzene. . . . 11-9
11-6 Cumulative Urinary and Fecal Excretion of Pentachlorobenzene
and Metabolites During 40 Days Following a Single Oral Dose
of 0.5 mg/kg 1n Male and Female Rhesus Monkeys 11-12
11-7 Acute Oral Toxldty of Pentachlorobenzene 11-15
XVI
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_Noi_ Title Page
11-8 Summary of Subchronlc, Reproductive and Teratogenlc
Toxldty Studies on Pentachlorobenzene 11-17
11-9 Reproductive Effects 1n Litters of Female Rats Fed Diets
Containing Pentachlorobenzene 11-21
11-10 Toxic Effects of Pentachlorobenzene on Reproduction 1n
Rats Dosed on Each of Gestation Days 6-15 11-23
11-11 Skeletal and Soft-Tissue Abnormalities Observed 1n Rat
Litters of Dams Treated with Pentachlorobenzene on Each
of Gestation Days 6-15 11-24
11-12 Fetal Wlstar Rat Residues of Pentachlorobenzene 11-25
12-1 Storage and Excretion of 14C-HCB Administered Orally
1n Arachls 011 1n Rats 12-4
12-2 Tissue Concentration (ppm) of 14C-Hexachlorobenzene
and Its Metabolites 1n Sprague-Dawley Rats 12-6
12-3 Tissue Levels of HCB (ppm) 1n Adult Female Rhesus Monkeys . . 12-7
12-4 HCB Concentrations 1n Tissues of Male Beagles Receiving
Single Intravenous Doses of 1 mg/kg bw 1n Olive 011 12-9
12-5 Mean (^SE) Hexachlorobenzene Radioactivity (dpm/g) of
Selected European Ferret Tissues 12-14
12-6 Mean dSE) HCB Radioactivity (dpm x 103) of European
Ferret Kits 12-15
12-7 Concentrations of HCB and Us Metabolites (mg/kg) In the
Liver and Kidneys of Male and Female Rats 12-19
12-8 Hexachlorobenzene and Its Major Metabolites 1n the Excreta
of Different Animal Species 12-21
12-9 Results of Blood and Urine Analysis 1n Men Employed 1n a
Chlorinated Solvents Plant, 1974-1977 12-31
12-10 HCB Plasma Levels 1n Exposed Individuals and Controls .... 12-33
12-11 Clinical Signs and Symptoms 1n Humans 25 Years After
Exposure to Low Levels 1n HCB 1n Turkey, 1955-1959 12-36
12-12 Porphyrln Levels 1n Patients and Controls 12-38
12-13 Laboratory Test Results of Turkish Patients 12-39
12-14 Summary of Toxidty Studies on Hexachlorobenzene 12-43
XV I I
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No. Title _Page_
12-15 PorphyMn Content and Uroporphyrlnogen Oecarboxylase
Activity 1n the Liver Cytosol of Female Rats Pretreated
with 100 mg/kg HCB Every Other Day for 6 Weeks. ....... 12-53
12-16 Tumor Incidence 1n Hamsters Given HCB 1n the Diet 12-62
12-17 HCB Levels 1n Tissues of Male Rats Following Administration
of 8 mg/kg 1n Sunflower 011 for 19 Days 12-64
12-18 HCB Levels 1n Tissues of Male Rats Following Administration
of 14C-HCB 1n Arachls 011 12-65
12-19 Effect of HCB on Hamsters: Liver Tumors and Other Liver
Lesions 12-69
12-20 Liver Tumor Incidence 1n Mice Fed HCB 12-71
12-21 Tumor Data on Mice Fed HCB. 12-72
12-22 Body Weights of Female Agus Rats Fed Hexachlorobenzene
for 90 Weeks 12-76
12-23 Growth Rates for Female Agus Rats on a Diet Containing
100 ppm HCB 12-78
12-24 Dosage Levels 1n the Chronic Feeding Study of
Hexachlorobenzene 1n Sprague-Dawley Rats 12-81
12-25 Liver and Kidney Tumors 1n Sprague-Dawley Rats GWen
Hexachlorobenzene 1n the Diet for up to 2 Years ....... 12-82
12-26 Adrenal Tumors 1n Sprague-Dawley Rats Given
Hexachlorobenzene 1n the Diet for up to 2 Years 12-84
12-27 Exposure Levels 1n the Chronic Feeding, 2-Generat1on
Study of Hexachlorobenzene 1n Sprague-Dawley Rats 12-86
12-28 Tumors 1n Organs that Showed Statistical Differences
from Control 1n F-j Sprague-Dawley Rats Treated with
Hexachlorobenzene ... 12-88
12-29 Parathyroid and Adrenal Pheochromocytomas 1n Sprague-
Dawley Rats Maintained on Synthetic Diets of Varying
Vitamin A Content and With or Without Hexachlorobenzene . . . 12-89
12-30 Qualitative Comparison of Tumor Development 1n Rats
Following Hexachlorobenzene Administration 1n Different
Studies 12-92
12-31 Tumor Incidences 1n Male and Female Hamsters Given
Hexachlorobenzene 1n Diet 12-107
XVI I !
-------
JNp_-_ Title
12-32 Incidence of Liver Cell Tumors 1n Male and Female
Swiss Mice Given Hexachlorobenzene Diet 12-108
12-33 Liver and Kidney Tumor Incidence Rates 1n Male and
Female Sprague-Dawley Rats Given Hexachlorobenzene 1n Diet. . 12-109
12-34 Incidence Rate of Adrenal Pheochromocytoma 1n Female
Sprague-Dawley Rats (F-| generation) 1n a 2-Generat1on
Feeding Study . 12-110
12-35 The Carcinogenic Potency of Hexachlorobenzene, Calculated
on the Basis of 14 Data Sets, Using the Linearized
Multistage Model 12-113
12-36 Upper-Bound (Point) Estimation of Risk, Based on
Hepatocellular Carcinoma 1n Female Rats 12-115
12-37 Relative Carcinogenic Potencies Among 54 Chemicals
Evaluated by the Carcinogen Assessment Group as
Suspect Human Carcinogens 12-119
12-38 Significantly Increased Incidence of Tumors 1n
Animals Given Hexachlorobenzene 1n Diet 12-124
12-39 Analysis of the Excreta from Rats Administered Hexa-
chlorobenzene After an Initial Treatment with Dlethyl-
stllboestrol. ... 12-132
13-1 Summary of Subchronlc Toxldty Studies on Monochlorobenzene . 13-6
13-2 Subchronlc Toxldty of 1,2-D1chlorobenzene 13-9
13-3 Subchronlc Toxldty of 1,4-D1chlorobenzene 13-11
13-4 Summary of Subchronlc and Chronic Toxldty Studies on
Trlchlorobenzenes 13-13
13-5 Summary of Toxldty Studies on Tetrachlorobenzenes 13-15
13-6 Summary of Subchronlc, Reproductive and Teratogenlc
Toxldty Studies on Pentachlorobenzene 13-16
13-7 Summary of Toxidty Studies on Hexachlorobenzene 13-17
13-8 Comparison of Toxic Effects of Chlorinated Benzene
Isomers 1n Rats 13-22
13-9 Comparison of Toxic Effects of Chlorinated Benzene
Isomers 1n Mice 13-24
13-10 Comparison of Toxic Effects of Chlorinated Benzene
Isomers 1n Rabbits 13-26
XI X
-------
No. Title Page
13-11 Comparison of Toxic Effects of Chlorinated Benzene
Isomers 1n Dogs 13-28
13-12 Comparison of Toxic Effects of Chlorinated Benzene
Isomers 1n Monkeys 13-30
13-13 Toxldty Data for Threshold Estimates 13-32
13-14 Summary of Tumors Induced 1n Rodents by HCB 13-37
13-15 Comparison of Chemical and Physical Properties of
Chlorinated Benzenes 13-41
13-16 Comparison of Chlorinated Benzenes BCF and Water
Concentrations 13-42
13-17 Estimated Yearly Exposure to Several Chlorinated
Benzenes Via Inhalation 13-44
13-18 Occupational Standards for Monochlorobenzene 13 46
13-19 Occupational Standards for 1,2-D1chlorobenzene 13-48
13-20 Occupational Standards for 1,4~D1chlorobenzene 13-49
13-21 The Chlorinated Benzenes as Constituents of
Hazardous Wastes from Specific Sources 13-53
13-22 Ambient Water Quality Criteria for Chlorinated
Benzenes—Aquatic Life 13-56
13-23 Ambient Water Quality Criteria for the Chlorinated
Benzenes for the Protection of Human Health 13-57
13-24 Maximum Imm1ss1on Concentration Standards for
Monochlorobenzene 13-59
XX
-------
LIST OF FIGURES
No. Title Page
3-1 Chemical Structure of the Chlorinated Benzenes 3-2
7-1 Metabolism of Monochlorobenzene 7-7
9-1 Metabolic Pathways for TMchlorobenzene (KB) Isomers
Through Arene Oxide Intermediates 1n Rabbits 9-7
12-1 Histogram Representing the Frequency Distribution of
the Potency Indices of 54 Suspect Carcinogens Evaluated
by the Carcinogen Assessment Group 12-118
XXI
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1. INTRODUCTION
The purpose of this document 1s to summarize the current knowledge of
the effects of exposure to the chlorinated benzenes on human health.
The chlorinated benzenes are a group of 12 compounds 1n which 1 to 6
chlorine atoms have been substituted for the hydrogens on a benzene ring.
They are used as chemical Intermediates 1n the synthesis of pesticides and
other chlorinated compounds, and as solvents, pesticides, dye carriers,
space deodorants and other products. Environmental contamination results
from emissions to air and water during the manufacture and use of the
chlorinated benzenes and from the disposal of wastes from a number of pro-
cesses. These compounds are resistant to chemical and biological degrada-
tion and tend to accumulate 1n I1p1d-conta1n1ng tissues of animals and
humans. The ubiquitous environmental distribution of the chlorinated ben-
zenes and their bloconcentratlon 1n humans are a basis for concern over the
consequences of chronic exposure to human health.
The rationale for structuring the document Is based primarily on two
major Issues, exposure and response. The first portion of the document 1s
devoted to the chlorinated benzenes 1n the environment: physical and chemi-
cal properties, the monitoring of the chlorinated benzenes 1n various media,
natural and human-made sources, the transport and distribution of the
chlorinated benzenes within environmental media, and the levels of expo-
sure. The second part 1s devoted to biological responses 1n laboratory
animals and humans Including metabolism, pharmacoklnetlcs, as well as the
toxlcologlcal effects of the chlorinated benzenes.
1824A 1-1 03/09/84
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This assessment 1s based on original publications, although the overall
knowledge covered by a number of reviews and reports was also considered.
The references cited were selected to reflect the current state of knowledge
on those Issues which are most relevant for a health assessment of the
chlorinated benzenes 1n the environment.
1824A 1_2 7/5/83
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2. SUMMARY AND CONCLUSIONS
2.1. SUMMARY
2.1.1. Properties, Production and Use. The chlorinated benzenes are a
group of cyclic aromatic compounds 1n which 1-6 hydrogen atoms of a benzene
ring have been replaced by up to six chlorine substHutents. This substitu-
tion yields 12 compounds: monochlorobenzene, three 1somer1c forms of
dlchlorobenzene, three Isomers of trlchlorobenzene, three Isomers of tetra-
chlorobenzene, pentachlorobenzene and hexachlorobenzene. The physical prop-
erties of these compounds vary with the degree of substitution of each and
are, 1n general, low water solubility (solubility decreasing with Increasing
chlorlnatlon), low flammabllHy, moderate to high octanol/water partition
coefficients (coefficients Increasing with Increasing chlorlnatlon) and low
to moderate vapor pressures (vapor pressures decreasing with Increasing
chlorlnatlon). They are chemically unreactlve and exist as liquids or
solids at environmental conditions. Analysis of airborne chlorobenzenes are
usually accomplished by adsorption onto sorbent cartridges, followed by-
thermal desorptlon and analysis by gas chromatography (GC). For water
samples, the purge-trap method 1s used to concentrate the volatile halo-
genated benzenes before analysis by GC. For less volatile chlorinated ben-
zenes, solvent extraction followed by column chromatographlc cleanup of the
extract and electron capture/gas chromatography (EC/GC), 1s the most com-
monly used method for the Isolation, detection and quantification. Methods
similar to those used for wastewater samples are commonly used for the
analysis of chlorinated benzenes 1n biological matrices.
Annual production of these 12 chlorinated benzenes 1n 1983 1s on the
order of 450 million pounds, the majority of which 1s accounted for by mono-
chlorobenzene and dlchlorobenzenes. These compounds are used 1n a number of
1825A 2-1 03/26/84
-------
organic chemical syntheses, Including the synthesis of other chlorobenzenes,
and have applications as solvents, electrical equipment Insulators, pesti-
cides, herbicides and fungicides. Emissions of chlorobenzenes are most
likely to occur during their manufacture or use as Intermediates and from
the disposal of waste products from manufacturing operations. Hexachloro-
benzene 1s Imported but not produced commercially 1n the United States, and
occurs as a by-product 1n the synthesis of nine other chlorinated hydro-
carbons; 2-5 million pounds may be generated each year.
2.1.2. Environmental Levels, Transport and Fate. Chlorinated benzenes
have been Identified 1n air, food and soil, and 1n surface, ground and
drinking water. The highest concentrations have been found In or near manu-
facturing and waste disposal sites, although no study has attempted to char-
acterize the contribution of any one source to the total environmental con-
tamination by chlorobenzenes. Ambient air and water levels are 1n the
m1crogram/cub1c meter and mlcrogram/Hter range, respectively, although
monitoring studies for finished water have been limited. The most fre-
quently detected chlorinated benzenes 1n air and water were monochloroben-
zene and the d1- and tMchlorobenzenes. Penta- and hexachlorobenzene have
been found more frequently 1n food and soil, although their detection may
reflect more the concern over their use as pesticides and fungicides, or
their presence as contaminants 1n pesticides or fungicides, rather than the
absence of the other chlorobenzenes.
The transport and fate of the chlorinated benzenes In the environment
have not been well characterized although, from laboratory and field studies
and from the known chemical and physical properties, several generalizations
can be made. After emission Into air, the chlorobenzenes are likely to be
widely dispersed by the prevailing wind and degrade slowly through chemical
1825A 2-2 03/26/84
-------
and photolytlc reactions. One study estimated residence times for three of
the chlorobenzenes to range from 13-116 days. When released Into water,
these compounds, because of their low water solubility will evaporate from
the surface rapidly. Small amounts are likely to remain 1n solution or be
removed through sedimentation. Some of the chlorobenzenes can undergo
mlcroblal degradation, and all show a propensity for bloaccumulatlon. After
release of chlorobenzenes Into soil, very little will be removed by leaching
with water because of low water solubility and high soil adsorption; the
latter Increases with the number of substHuent chlorines. Evaporation 1s
likely to occur from the upper soil layers. Overall, the less chlorinated
chlorobenzenes will tend to partition from soil and water Into air, there to
be dispersed and degraded. The chlorobenzenes will also tend to enter the
atmosphere, either as partlculates or vapors, and disperse, degrade or
precipitate out.
The chlorinated benzenes are UpophlUc compounds that bloaccumulate 1n
animal and human tissues from ambient air, water and food. The bloconcen-
tratlon factor (BCF) (tissue concentration/media concentration) Is an
Indicator of bloaccumulatlon and can be expressed 1n terms of such physico-
chemical parameters as the water solubility or the octanol/water partition
coefficient which reflect the number of substHuent chlorine atoms. The BCF
1n various fish species range from 12-46 for monochlorobenzene to >44,000
for hexachlorobenzene. Physiological exposure levels (the levels of expo-
sure, concentration, at the site of the compounds Interaction, sequestration
or observed effects) are determined by absorption, metabolism, elimination
and storage 1n adipose tissue; thus, biologically persistent compounds, such
as the chlorinated benzenes, may produce prolonged physiological exposures.
1825A 2-3 03/26/84
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No comprehensive study of human exposure to the chlorinated benzenes has
been conducted, although their ubiquity 1n the environment and the detection
of measurable residues 1n human tissue Indicate that human exposure and
absorption occur. The contribution of the chlorinated benzenes from all
three media (air, water and food) to a person's total exposure cannot be
made with the limited environmental monitoring data. The available data,
however, Indicate that human Inhalation exposure to chlorinated benzenes may
i
be higher than 1ngest1on exposure either through drinking water or through
foods.
2.1.3. Ecological Effects. As demonstrated 1n acute toxldty bloassays,
the LC 1n fish generally decreases as the number of substHuent chlorine
atoms on the molecule Increases (Isomers vary). Chlorinated benzenes cause
adverse reproductive effects 1n Invertebrates and fish. Monochlorobenzene
tested 1n goldfish and largemouth bass, 1,3,5-tr1chlorobenzene tested 1n
brine shrimp, and the exposure of sheepshead minnows to 1,2,4,5-tetrachloro-
benzene resulted 1n decreased hatching of eggs or embryo lethality and
decreased survival of juvenile fish.
Adverse effects of chlorinated benzenes were also apparent In terres-
trial organisms. Mitosis 1n seeds and seedlings was disrupted by 1,4-dl-
chlorobenzene; 1,2,4,5-tetrachlorobenzene affected seed germination and
seedling growth depending on soil type. Soil application rates of 224 kg/ha
or higher of 1,2,4,5-tetrachlorobenzene were found to be toxic to mature
cotton plants. Dlchlorobenzene vapors at "saturation concentrations"
Inhibited the emergence of housefly pupae, while 1,2-d1chlorobenzene and
trlchlorobenzene each 1n dlesel oil were toxic to Douglas fir beetles.
1825A 2-4 03/26/84
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Contact with residues of 1,3,5-tr1chlorobenzene shortened the Hfespan of
female wasps, and their eggs suffered high mortality within 7 days of
exposure.
Although effects of chlorinated benzenes (mortality, decreased reproduc-
tion) on natural populations have not been adequately studied, tissue
concentrations of several Isomers were measured 1n a number of different
species. Aquatic organisms {fish and Invertebrates) and terrestrial species
have been found to contain chlorinated benzenes levels. Tissue concentra-
tions of the quantHated chlorinated benzenes were highest for hexachloro-
benzene. The detection In North America and Europe of hexachlorobenzene 1n
the eggs of birds and subcutaneous fat of wild animals suggests Its wide-
spread distribution 1n the environment.
2.1.4. Pharmacok1net1cs. Monochlorobenzene 1s readily absorbed through
the respiratory system and the gastrointestinal tract, but the quantitative
extent 1s not known. It 1s deposited 1n body Uplds and metabolized by
mlcrosomal oxidation. Ox1dat1ve reactions lead to the formation of arene
oxides; these epoxldes are metabolized further to the ortho-, meta- or
para-chlorophenols. The chlorophenols may conjugate with glutathlone and be
detoxified by conversion to the corresponding mercaptuMc adds and excreted
1n the urine or they may bind to cellular proteins. Binding to cellular
protein appears to be correlated with necrotlc pathological changes 1n the
kidneys and livers of rodents. In addition to conjugation with glutathlone,
metabolites of monochlorobenzene (monophenols and dlphenols) can conjugate
with glucuronlc add or with sulfate and be excreted 1n the urine. Mono-
phenols are the major metabolites; the dlphenols are formed to a lesser
degree. The arene oxides, 3-chlorobenzene oxide or 4-chlorobenzene oxide,
1825A 2-5 03/27/84
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also can be converted to the dlhydrodlol by epoxlde hydrase and dehydro-
genated to form chlorocatechols. There appear to be species differences 1n
the profile of urinary conjugation of metabolites, and end metabolites may
vary depending on the availability of tissue glutathlone. Detoxification by
conjugation with glutathlone is Important 1n the modulation of toxic effects
especially at high exposure levels.
The available data for rats, rabbits and humans Indicate that the
dlchlorobenzenes are absorbed through the lungs, gastrointestinal tract and
Intact skin, though actual determinations of absorption rates were not
located. Once absorbed through either Inhalation or 1ngest1on, the
dlchlorobenzenes are rapidly distributed to many tissues, Including blood,
adipose, kidney, liver, lung, heart, brain and muscle tissues. Distribution
1s primarily to adipose tissue, which has Initial levels 10-32 times the
blood concentrations and to lung and kidney tissues to a greater extent than
liver, muscle and plasma. Single-dose and repeated exposures by both Inha-
lation and 1ngest1on show similar patterns of distribution. Elimination of
the dlchlorobenzenes and their metabolites occurs within 5-6 days after
exposure, although elimination from adipose tissue 1s slowest and l,2-d1-
chlorobenzene and metabolites are eliminated slightly more rapidly than
1,4-d1chlorobenzene. The dlchlorobenzenes are primarily metabolized by
hydroxylatlon to their respective dlchlorophenols, which are excreted 1n the
urine 1n the form of glucuronlc and sulfate conjugates. Some metabolites
are excreted 1n the bile, although the majority are then reabsorbed by the
enterohepatlc pathway and reexcreted 1n the urine. Intermediates of the
metabolism of 1,4-d1chlorobenzene, possibly arene oxides, bind to liver
protein and may be Involved 1n the Induction of hepatotoxldty.
1825A 2-6 03/26/84
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The limited comparative pharmacoklnetlc data available on the trlchloro-
benzenes prevent specification of the absorption, distribution, metabolism
and excretion of the Individual Isomers. From the available data, H
appears that metabolism 1n at least three species has a common first step,
the production of an arene oxide Intermediate. Subsequent metabolic steps,
however, vary among the species examined, at least for the most studied
Isomer, 1,2,4-tr1chlorobenzene.
In general, the pharmacoklnetlcs of the trlchlorobenzenes are similar to
those described for the other halogenated aromatlcs. These compounds are
UpophlUc and their metabolism and excretion depend on conversion to polar
Intermediates. In addition, their UpophlUc character provides for ready
absorption from the gastrointestinal tract and Initial distribution to the
more highly perfused tissues, particularly the liver, after which they are
either metabolized and excreted or redistributed to adipose tissue or skin.
Additional experiments are needed to clarify the relationship of these
studies to the metabolism of trlchlorobenzenes 1n humans.
No studies describing the absorption, distribution, metabolism or excre-
tion of 1,2,3,4-, 1,2,3,5- or 1,2,4,5-tetrachlorobenzene following Inhala-
tion exposure were located 1n the available literature. The pharmaco-
klnetlcs of the tetrachlorobenzene Isomers following oral administration 1s
well characterized 1n rabbits, but not 1n other animal species. The Upo-
phlUc characteristics of the tetrachlorobenzene Isomers would allow effi-
cient transepHhellal absorption at the gastrointestinal and respiratory
surfaces. Once absorbed, the tetrachlorobenzene Isomers administered orally
to rabbits were rapidly accumulated 1n fat, metabolized primarily to tetra-
chlorophenols and conjugated partly as glucuronldes and ethereal sulfates or
eliminated unchanged 1n the expired air or feces.
1825A 2-7 03/26/84
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No pharmacoklnetlc data were available for humans, except a report of
1,2,4,5-tetrachlorobenzene 1n adipose tissue (range of 0.006-0.039 mg/kg bw;
mean of 0.019 mg/kg bw) of 15 Tokyo residents. The tetrachlorobenzene
Isomers are both In^ vivo and in vitro metabolites of the pesticides, llndane
and hexachlorobenzene; therefore, human exposure via air, food and drinking
water may occur from the environmental degradation of these pesticides.
Although studies of the absorption of pentachlorobenzene Indicated that
absorption does occur through the gastrointestinal tract, the rate or extent
of absorption has not been determined. A study 1n rabbits indicated that up
to 50% of a dose was absorbed within 3-4 days. Oral administration to
monkeys Indicated 95% absorption within 4 days. Absorption resulting from
Inhalation has not been studied, and absorption from dermal exposure was
found to be rather poor 1n rats. Once absorbed, pentachlorobenzene 1s dis-
tributed to many tissues, with the highest levels appearing In fat, liver
and bone marrow. A study 1n rats demonstrated that transport across pla-
centa! membranes occurred readily and that accumulation of pentachloroben-
zene in the fetus 1s highest in the liver. No studies were encountered that
described the distribution of pentachlorobenzene after inhalation or dermal
exposure.
The metabolism of pentachlorobenzene 1s not fully understood, but some
studies suggested that metabolic activity other than the hepatic cytochrome
P-450, xenobiotic metabolizing system may be Involved. Metabolism appeared
to be primarily via oxidation to two major metabolites, pentachlorophenol
and 2,3,4,5-tetrachlorophenol, which were excreted in the urine. Metabolism
and excretion occurred at a slow rate; an estimated elimination half-life
for a single dose in primates was 2-3 months.
1825A 2-8 03/26/84
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The pharmacoklnetlcs of hexachlorobenzene 1n a number of mammalian
species have been studied 1n detail following oral administration and, to a
lesser extent, following Intravenous or 1ntraper1toneal Injection. No
Information was present 1n the available literature on hexachlorobenzene
metabolism following Inhalation or topical application. Absorption of
hexachlorobenzene from the Intestinal tract appears to depend on the vehicle
used during test material administration. Thus, when hexachlorobenzene 1s
administered 1n olive oil, -80% of the dose 1s absorbed; when 1t 1s adminis-
tered 1n an aqueous solution, 1n IX methyl cellulose or 1n a crystalline
form, relatively little (<20%) 1s absorbed. Intestinal absorption of
hexachlorobenzene occurs primarily through lymphatic channels, with only a
minor portion being absorbed Into the portal circulation.
Following absorption, hexachlorobenzene 1s distributed to tissues that
have a high I1p1d content. The adipose tissue accumulates the greatest
concentrations of hexachlorobenzene 1n all species studied, although bone
marrow and skin, which contain large amounts of Uplds, also accumulate
hexachlorobenzene. The adrenal cortex accumulates hexachlorobenzene at con-
centrations approaching those of fat. Other body constituents (e.g., kid-
neys, lungs, heart, spleen and blood) generally contain much lower amounts
of hexachlorobenzene. Intravenous Injection of hexachlorobenzene results 1n
a tissue distribution similar to that seen following oral administration.
Hexachlorobenzene 1s transported via the placenta and 1s distributed 1n
fetal tissue as Indicated by studies 1n rabbits, rats, mice, mink and
ferrets.
t
Hexachlorobenzene 1s metabolized slowly Into other chlorinated benzenes,
chlorinated phenols and other minor metabolites and forms glucuronlde and
glutathlone conjugates. Tissues were found to contain mainly unchanged
1825A 2-9 03/26/84
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hexachlorobenzene together with small amounts of metabolites. Similarly,
only small amounts of hexachlorobenzene metabolites were detected 1n feces,
whereas most of the metabolites were excreted 1n the urine together with
small amounts of unchanged hexachlorobenzene. There are Indications that
females produce and excrete more hexachlorobenzene metabolites than do males.
The excretion of hexachlorobenzene from treated animals Is slow and
occurs mainly through the feces with relatively little being excreted 1n the
urine. It 1s characterized by an Initial rapid phase followed by a very
slow phase. This slow phase of excretion can be enhanced by the administra-
tion of mineral oil, paraffin or n-hexadecane. Both biliary and Intestinal
excretion contribute to fecal excretion. A three-compartment mammlllary
model has been reported for the behavior of hexachlorobenzene 1n beagles and
rhesus monkeys following 1.v. Injection of a single dose. Radioactivity was
not detected 1n exhaled air following 1.p. Injection of 14C-hexachloroben-
zene. Hexachlorobenzene has been detected 1n the milk of nursing mammals.
2.1.5. Effects on Humans. No ep1dem1olog1c studies regarding the effects
of exposure to monochlorobenzene are available. Human exposure to mono-
chlorobenzene by Inhalation or by accidental 1ngest1on can cause neurotoxlc
effects. It 1s not known 1f the effects are reversible after long-term
exposure or 1f there are other sites of toxldty.
Ep1dem1olog1c data on dlchlorobenzenes are Insufficient to evaluate
dose-response association. Possible chronic effects of exposure to the
dlchlorobenzenes are Indicated by case reports of the chronic exposure of
Individuals, I.e., repeated exposures over a period of more than a year,
suggesting a common set of toxic effects, those of the retlculoendothellal
and hematopoletlc systems and those of the liver. Of the 23 exposure cases
found 1n the literature, 17 Involved pathological changes 1n the blood or
1825A 2-10 03/26/84
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liver, Including chronic lymphold leukemia, acute hemolytlc anemia, aplastlc
anemia and bone marrow hyperplasla. Although the exposures 1n these cases
are not well defined 1n time and often Involve other toxic substances,
together they suggest a common pathologic action of the dlchlorobenzenes on
bone marrow and other organs of the blood-forming system. The one available
ep1dem1olog1c study supports this generalization 1n that the reported
short-term exposure to l,2-d1chlorobenzene (8 hours/day for 4 days) produced
alterations 1n the chromosomes of leukocytes. This study did not establish
an association between chromosomal alterations and the pathologic changes
that characterize the case studies.
Human exposure to 1,2,4-tMchlorobenzene at 3-5 ppm causes eye and
respiratory Irritation. The only other data on human exposure are Individ-
ual case reports of aplastlc anemia of persons exposed occupationally or
domestically.
Only one ep1dem1olog1c study was available regarding the effects of the
tetrachlorobenzenes on humans and this study examined peripheral lymphocytes
for chromosomal abnormalities 1n blood. The blood was collected from
Hungarian workers engaged 1n the production of 1,2,4,5-tetrachlorobenzene.
There were observed chromosome aberrations 1n the lymphocytes; however, no
airborne concentrations or exposures were determined.
No ep1dem1olog1c or case studies of effects on humans resulting from
exposure to pentachlorobenzene were available for review.
A few ep1dem1olog1c studies with occupationally-exposed workers have
been reported, together with studies conducted 1n Turkey and 1n the United
States (I.e., Louisiana) on the general population following accidental
exposure to hexachlorobenzene. These studies qualitatively support the
toxldty of hexachlorobenzene, but give little dose-response Information.
1825A 2-11 03/26/84
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Biological monitoring of plasma levels clearly show more hexachlorobenzene
1n the plasma of exposed compared to nonexposed Individuals, although no
biologically significant adverse health effects were seen during the obser-
vation periods. The exposure of humans to hexachlorobenzene In Turkey
during 1955-1959 caused an epidemic of hexachlorobenzene-lnduced porphyrla
cutanea tarda (PCT), also known as porphyrla turdca, which 1s manifested by
disturbed porphyMn metabolism, cutaneous lesions and hyperplgmentatlon.
The authors estimated that from 0.05-0.2 g/day were Ingested. In exposed
children under 1 year of age, pink sore was observed as well as 95% mortal-
ity 1n these Infants.
Follow-up studies conducted with patients 20-25 years after the onset of
porphyrla showed that a few subjects still had active porphyrla, whereas
>50% exhibited hyperplgmentatlon scarring, as well as other dermatologlc,
neurologic and skeletal features of hexachlorobenzene toxldty. Hexachloro-
benzene residues were also found 1n the blood, fat and breast milk of some
patients.
A correlation was found between hexachlorobenzene levels 1n blood and
the number of years worked 1n a chlorinated solvents plant. The concentra-
tion of urinary uroporphyrlns and coproporphyMns ranged from 21-37 and
67-101 yg/d, respectively, for the period between 1974 and 1977. An
ep1dem1olog1c survey conducted with 86 residents 1n the vicinity of this
chlorinated solvents plant showed elevated hexachlorobenzene residues 1n
plasma. Higher levels of hexachlorobenzene residues were found 1n males
than 1n females, but these were not associated with race or food consumption.
2.1.6. Mammalian Toxicology. Acute exposure to monochlorobenzene by
Inhalation causes sensory Irritation of the respiratory system after a few
minutes; exposure for several minutes to several hours causes narcosis and
1825A 2-12 03/26/84
-------
central nevous system depression, which can result 1n death. Monochloroben-
zene 1s also toxic by the oral or parenteral routes. Systemic effects of
acute toxic doses Include kidney damage. Subchronlc Inhalation exposure at
1.0 mg/m3 (contlnously for 60 days) causes neurotoxlc effects 1n rats, an
Increase 1n blood chollnesterase and abnormal chronaxla of the muscles.
Repeated exposure of rats to monochlorobenzene at 250 ppm (1157 mg/m3)
causes slight changes 1n the liver, kidneys and adrenal cortex. Repeated
oral dosing of rats or dogs (100-200 mg/kg/day) causes some toxic manifesta-
tion 1n the liver and kidneys. Gavage administration of monochlorobenzene
to mice and rats 5 times/week for 13 weeks resulted 1n Increased mortality
1n the higher dose groups (>250 mg/kg), urinary porphyrla and dose-dependent
Injury to the liver, kidney, bone marrow, spleen and thymus. A set of sim-
ilar studies were conducted 1n mice and rats for 2 years and resulted 1n
some Increased mortality 1n the male monochlorobenzene exposed groups when
compared with controls. Only equivocal evidence for mild monochlorobenzene-
Induced hepatocellular necrosis was found 1n rats.
Although one study 1n Streptomyces antlblotlcus found monochlorobenzene
to Induce reversion to vitamin B. prototrophy and one study 1n Saccharo-
myces cerevlslae showed Induction of DNA damage, several other studies using
bacterial, fungal and mammalian tissue culture systems were negative. The
carcinogenic activity of monochlorobenzene was tested by the NTP bloassay
program 1n two rodent species at doses of 60 and 120 mg/kg bw/day In male
and female rats and female mice, and at 30 and 60 mg/kg bw/day 1n male mice.
Carc1nogen1c1ty was not demonstrated for monochlorobenzene 1n this study,
but high dose male rats had a significant Increase 1n neoplastlc nodules of
the liver.
Repeated exposures to monochlorobenzene at 2.0 mg/8. (vapors) or 0.250
mg/kg/day (oral) were found to cause atrophy of the epithelial tissue In the
1825A 2-13 04/16/84
-------
seminiferous tubules and decreased spermatogenesls 1n dogs and rats and
Increased gonad weight/body weight ratios 1n female rats.
Studies of the acute and subchronlc toxldty of the dlchlorobenzene
Isomers Indicate that generally these compounds have similar target organs
and effects. At oral doses ranging from 125-1000 mg/kg over periods of up
to 6 months, the dlchlorobenzenes cause central nervous system depression,
Injury to liver, kidney, heart, thymus and spleen, and hepatic porphyrla;
however, one study reported that a dose of 0.01 mg/kg over a 5-month period
Inhibited erythropolesls and bone marrow activity. The subchronlc oral
toxldty studies 1n rats provide two estimates of no-observed-effect level
(NOEL) values: 0.001 mg/kg for 1,4-dlchlorobenzene and 18.8 mg/kg for 1,2-
and for 1,4-d1chlorobenzene. The National Toxicology Program (NTP, 1982)
subchronlc oral study on 1,2-d1chlorobenzene 1n mice provided higher esti-
mated NOEL values of 125 and 250 mg/kg for males and females, respectively.
A 2-year NTP chronic oral gavage study on 1,2-d1chlorobenzene 1n rats and
mice, conducted primarily as a carclnogenesls bloassay at the 60 and 120
mg/kg dose levels, resulted only 1n Increased mortality 1n the male rats
given 120 mg/kg. Acute and subchronlc Inhalation studies of dlchloroben-
zenes Indicate similar toxic effects and target sites as seen In the oral
studies. The effects occurred at doses >950 mg/m3; inhalation NOELs were
reported as 580 mg/m3 for 1,2-dichlorobenzene and 290 mg/m3 for
1,4-d1chlorobenzene.
Studies of the mutagenlc activity of dlchlorobenzenes show little or no
activity in a range of bacterial systems, Including Salmonella, with and
without metabolic activation. However, these studies were lacking in exper-
imental detail. Several studies with mold and plant cultures treated with
dlchlorobenzenes have reported mutations and chromosomal alterations. The
carcinogenic activity of one Isomer, 1,2-d1chlorobenzene, was tested in the
1825A 2-14 04/16/84
-------
NTP bloassay program 1n two rodent species at doses of 60 and 120 mg/kg. No
evidence of carcinogenic activity was found under the test conditions.
The effects 1n mammals of acute exposure by various routes to trlchloro-
benzenes Include local Irritation, convulsions and death. Livers, kidneys,
adrenals, mucous membranes and brain ganglion cells appear to be target
sites with effects Including edema, necrosis, fatty Infiltration of livers,
Increased organ weights, porphyMn Induction and mlcrosomal enzyme Induction.
Quantitative data on the toxic effects of trlchlorobenzene following
subchronlc exposure by various routes were obtained 1n a variety of species.
In general, these studies Indicate that the liver and kidney are target
organs. Inhalation of 1,2,4-tMchlorobenzene at >74.2 mg/m3 (10 ppm) for
6 hours/day, 5 days/week for up to 26 weeks Induced hepatocytomegaly and
hyaline degeneration 1n several species, although these effects may be to
some extent reversible. One study Identified 22.3 mg/m3 (3 ppm) as a no-
observed-adverse-effect level (NOAEL) 1n rats, while another study reported
that some rats exposed by Inhalation to 1,3,5-tr1chlorobenzene at 7423
mg/m3 (1000 ppm) for 13 weeks showed squamous metaplasia and focal hyper-
plasla of the respiratory epithelium, which appeared to be reversible.
Subchronlc oral studies have also found that the trlchlorobenzenes Induce
hepatic xenoblotlc metabolism and porphyrla. Subchronlc dermal exposure
resulted 1n mild to moderate Irritation.
One chronic study on the effects of trlchlorobenzene (0.03 mfc) painted
on the skin of mice for 2 years reported Increased mortality 1n females at
the low dose (30% solution 1n acetone) and 1n both sexes at the high dose
(60% solution).
Results of two reports on mutagenldty tests with Salmonella typhlmuMum
test strains were negative. However, this test system 1s generally Insensi-
tive to chlorinated compounds. One carc1nogen1c1ty study, a 2-year skin
1825A 2-15 04/16/84
-------
painting study 1n mice, failed to demonstrate a tumorlgenlc effect. A
multlgeneratlon study of the reproductive effects of oral exposure of rats
to trlchlorobenzene and an oral teratogenUHy study 1n rats failed to show
effects on reproduction or fetal development, although pups had mild osteo-
genlc changes.
The only mammalian toxicology data available for tetrachlorobenzenes are
the result of oral exposures. The oral L05Q for 1,2,4,5-tetrachloroben-
zene was reported as 1035 mg/kg 1n mice and 1500 mg/kg 1n rats and rabbits
when administered 1n sunflower oil and 2650 mg/kg 1n mice when administered
1n 1.5% starch solution. Subchronlc oral exposure of rats and rabbits to
1,2,4,5-tetrachlorobenzene resulted 1n statistically significant effects on
biochemical parameters, Including retlculocytosls, Increased blood chollnes-
terase activity, erythremla and an Indication that glycogen formation was
Impeded; at higher doses of 1,2,4,5-tetrachlorobenzene, rats also had
Increased kidney and liver weights, and renal and hepatic hlstologlc changes.
Reversible effects on serum alkaline phosphatase and total blllrubin
were reported 1n dogs given 5 nig/kg bw/day 1,2,4,5-tetrachlorobenzene In the
diet for 2 years.
1,2,4,5-Tetrachlorobenzene was not mutagenlc 1n the sex-linked recessive
lethal assay with DrosophUa melanogaster. However, because only an
abstract of the study was available, experimental details were too sparse to
permit an evaluation of this negative result. Both 1,2,3,5- and 1,2,4,5-
tetrachlorobenzenes were negative 1n the reverse mutation assay with Salmo-
nella typhlmurlum strains TA98, TA100, TA1535, TA1537 and TA1538. These
results were reported 1n an abstract with Insufficient experimental detail.
Also, a negative result for chlorinated compounds In the Salmonella rever-
sion assay 1s not unexpected.
1825A 2-16 04/16/84
-------
No Information was available regarding the carc1nogen1c1ty of any of the
three tetrachlorobenzene Isomers 1n either animals or humans.
The tetrachlorobenzene Isomers have been found to Induce appreciable
maternal toxldty, mild fetotoxlclty and negligible teratogenlclty 1n rats
following oral administration.
Oral LD values were determined for pentachlorobenzene 1n adult rats
(1080-1125 mg/kg) and mice (1175-1370 mg/kg), and for weanling rats (940
mg/kg). No clinical signs of toxldty were observed 1n adult rats following
dermal application of 2500 mg/kg pentachlorobenzene. Also, 1t was demon-
strated that pentachlorobenzene caused an Increase 1n the liver content of
cytochrome P-450, mlcrosomal drug metabolizing enzymes and mlcrosomal
proteins.
A subchronlc feeding study Indicated that the primary toxic effects are
on the liver and kidneys, although slight changes 1n some hematologlc param-
eters (e.g., decreased erythrocyte count, hemoglobin and hematocrlt; and
Increased leukocyte count) occurred 1n the high dose groups. H1stolog1c
examination Identified pathologic changes 1n the livers of the female rats
fed 500 and 1000 ppm for 180 days and 1n the 1000 ppm male rats treated for
100 days. These data were sufficient to Identify a subchronlc lowest-
observed-adverse-effect level (LOAEL) of 500 ppm (-27-63 mg/kg/day) and a
NOEL of 250 ppm (-16-31 mg/kg/day).
No mutagenlc activity was detected In five strains of Salmonella typhl-
murlum when tested at five unspecified concentrations of pentachlorobenzene
1n the presence and absence of rat liver mlcrosomes Induced by Aroclor
1254. These results were reported 1n an abstract with Insufficient experi-
mental details presented. A negative result 1s not unexpected, because the
Salmonella test system 1s generally Insensitive to chlorinated compounds.
1825A 2-17 04/16/84
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Studies also have shown that pentachlorobenzene Is capable of causing
reproductive and developmental effects. Female rats fed diets containing
pentachlorobenzene during mating and gestation produced Utters with reduced
pup survival and body weights at weaning, and Increased llver-to-body weight
ratios. No adverse effects were observed 1n the offspring of the dams
exposed to 125 ppm (6-16 mg/kg/day).
Single oral doses of pentachlorobenzene given dally to pregnant rats
during gestation Increased the Incidence of fetal death at all tested doses,
Identifying a LOAEL of 50 mg/kg/day. Sternal defects and an Increase 1n the
Incidence of extra ribs also were observed at doses of 200 mg/kg/day and 50,
100 and 200 mg/kg/day, respectively.
In a study of possible reproductive and teratogenlc effects, doses of 50
and 100 mg/kg/day of pentachlorobenzene administered by gavage to pregnant
mice had no adverse effect on fetal development or survival of the pups.
The acute oral toxldty of hexachlorobenzene has been found to be low
with LD values ranging from 1700-10,000 mg/kg. Subchronic oral toxldty
studies with a number of mammalian species Indicated a significant Increase
1n liver and kidney weights 1n hexachlorobenzene-treated animals. Studies
have shown Increases 1n other organ weights as well. The livers from hexa-
chlorobenzene-exposed animals have shown hlstologlc changes such as Irregu-
lar shaped and moderately enlarged liver mitochondria and Increases 1n the
size of the centrllobular hepatocytes. Chronic toxldty studies revealed
the same type of effects seen 1n the subchronlc studies, plus hexachloroben-
zene associated life-shortening and various hepatic and renal pathologies.
These subchronlc and chronic effects were usually dose-related. Other
effects Included multiple alopecia and scabbing, together with neurologic
effects 1n rats, mice and dogs. A dose-related hlstopathologlc change In
the ovaries of monkeys has also been reported.
1825A 2-18 04/16/84
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Increased porphyMn levels 1n the liver and 1n urine have been reported
for all species studied except the dog. Hexachlorobenzene was found to
cause the accumulation of 0-H-stero1ds which Induce porphyrln biosynthesis
and to Inhibit uroporphyrlnogen decarboxylases. The Inhibition of uropor-
phyrlnogen decarboxylase appears to be from pentachlorophenol, a hexachloro-
benzene metabolite. Indications are that females are more susceptible to
hexachlorobenzene-lnduced porphyrla than are males, which may be related to
the females estrogen levels and greater hexachlorobenzene metabolism.
Hexachlorobenzene was reported to produce a mixed-type Induction of cyto-
chromes resembling that produced by a combination of phenobarbltal (P-450)
and 3,4-benzpyrene (P-448). In addition, the activities of several hepatic
mlcrosomal enzymes were found to be Induced by hexachlorobenzene.
Hexachlorobenzene did not Induce dominant lethal mutations In two stud-
ies but was reported to be mutagenlc 1n a yeast, S^ cerevlslae, assay at a
concentration of 100 ppm. Hexachlorobenzene possessed no detectable levels
of mutagenlc activity 1n the Salmonella h1st1d1ne reversion assay. The
chronic toxldty studies provide sufficient evidence of the carclnogenldty
of hexachlorobenzene 1n animals since there was an Increased Incidence of
malignant tumors of the liver 1n two species (haemang1oendothel1oma 1n ham-
sters and hepatocellular carcinoma 1n rats) as well as reports of hepatoma
1n mice, rats and hamsters. Hexachlorobenzene given to pregnant mice was
found to produce cleft palates and renal agenlsls 1n exposed pups. Cer-
tain chemicals were found to alter the toxldty of hexachlorobenzene 1n mam-
mals, whereas hexachlorobenzene pretreatment was reported to Increase CC1.
toxldty and alter the Immune responses of treated animals.
1825A 2-19 04/23/84
-------
2.2. CONCLUSIONS
The chlorinated benzenes are a group of 12 cyclic aromatic compounds 1n
which 1-6 hydrogen atoms of a benzene ring have been replaced by up to six
chlorine substltuents. As the benzene ring 1s Increasingly chlorinated
there are physlochemlcal trends towards Increased melting points, boiling
points, densities and log partition coefficients, and decreased volatility
and water solubility of the compounds.
A wide range and severity of chlorinated benzenes-Induced health effects
have been reported 1n rodents and other laboratory animals. Some of these
same effects have also been observed 1n chlorinated benzenes-exposed humans
as well, but the human reports are not as extensive or complete as the
animal studies. A review of the animal chlorinated benzenes health effects
literature also Indicates that there are some large data gaps existing for
several of the chlorinated benzene Isomers, especially for 1,3-d1chloro-
benzene, the trlchlorobenzenes and the tetrachlorobenzenes. The animal
studies Indicate a trend of Increasing toxldty with Increased chlorlnatlon
of the benzene ring, e.g., hexachlorobenzene 1s more porphyrlnogenlc than
monochlorobenzene. Adequate evidence of the carclnogenlclty of the
different chlorinated benzenes has only been shown for hexachlorobenzene.
Hexachlorobenzene has been classified as a probable carcinogen In humans.
2.3. NEEDS FOR FUTURE RESEARCH
Further studies should be conducted to determine detailed pharmaco-
klnetlcs of each of the chlorinated benzene Isomers (I.e., absorp-
tion, distribution, metabolism and excretion).
Further studies should be conducted to determine more thoroughly
the long-term toxldty and, 1n some cases, the carclnogenlclty of
many of the chlorinated benzene Isomers, except for hexachloro-
benzene where sufficient data already exists.
Further mutagenldty studies should be conducted on those chlori-
nated benzene Isomers which do not have sufficient mutagenldty
data available.
1825A 2-20 04/16/84
-------
Studies should be conducted to assess the potential of the chlori-
nated benzenes to cause DNA damage.
Teratogenldty, fetotoxldty and reproductive studies should be
conducted using various routes of exposure, with emphasis on the
Inhalation route, on all the chlorinated benzene Isomers.
Studies on the neurotoxlc effects of the chlorinated benzene
Isomers should be conducted using various routes of exposure, with
emphasis on the Inhalation route.
Studies should be conducted to assess for possible chlorinated
benzenes effects on alterations to the endocrine, hematopoletic and
1mmunolog1c systems 1n humans and animals.
Further studies need to be conducted on the porphyrla-produclng
properties of the chlorinated benzenes [I.e., the properties of the
chlorinated benzene molecules or their metabollte(s) which are
responsible for this adverse health effect 1n humans and animals].
Investigations need to be conducted Into the quantitative
structure-activity relationships of the chlorinated benzenes with
an effort to relate biological and health effects to physlochemlcal
properties.
Studies are needed to Identify the extent of human exposure from
each of the chlorinated benzene Isomers and the relative contri-
bution of the various environmental medlas to the total human
exposure.
Exposure and health assessments of Indoor air pollution by chlori-
nated benzenes need to be made. This 1s Important especially for
the dlchlorobenzenes which are present 1n household space deodor-
ants and moth repellants.
Ep1dem1olog1c studies need to be conducted on Individuals who are
occupatlonally exposed to the chlorinated benzenes, with particular
emphasis on those adverse health effects already observed 1n the
human and animal studies.
Further follow-up studies are needed concerning the health of the
Turkish Individuals who were exposed to hexachlorobenzene 1n the
1950's, with particular emphasis on their cancer Incidences.
1825A 2-21 04/16/84
-------
3. PHYSICAL AND CHEMICAL PROPERTIES/ANALYTICAL METHODOLOGY
The chlorinated benzenes are the group of substituted benzene compounds
1n which 1-6 hydrogen atoms of benzene are replaced by chlorine atoms with
no substHuents present other than chlorine and hydrogen. The chloMnatlon
of benzene can yield 12 different compounds: monochlorobenzene
(C H Cl); 1,2-, 1,3- and 1,4-d1chlorobenzene (C H Cl ); 1,2,3-,
6 D & " <-
1,2,4- and 1,3,5-tr1chlorobenzene (C^dg); 1,2,3,4-, 1,2,3,5- and
1,2,4,5-tetrachlorobenzene (C&H2C14); pentachlorobenzene (C6HC15);
and hexachlorobenzene (C6C1,). The chemical structures of these com-
pounds are shown 1n Figure 3-1.
3.1. SYNONYMS, TRADE NAMES AND IDENTIFICATION NUMBERS
Synonyms, trade names and Identification numbers for the 12 chlorinated
benzenes are listed 1n Table 3-1.
3.2. PHYSICAL AND CHEMICAL PROPERTIES
Some physical properties of the chlorobenzenes are shown 1n Tables 3-2
and 3-3. In general, the chlorinated benzenes have low water solubility,
moderate to high octanol/water partition coefficients and low to moderate
vapor pressures at 25°C, and low flammabllHy. Apart from hexachloroben-
zene, they are considered to be volatile compounds because their Henry's Law
constants are greater than 10~4 atm m3 q • mol"1 (MacKay et al.,
1979).
The chlorobenzenes are chemically very unreactlve compounds and are
generally stable under ambient conditions 1n the laboratory. Because of the
electron-withdrawing character of the chlorine atom relative to carbon, the
chlorobenzenes are highly resistant to electrophlUc attack (e.g., chlorlna-
tlon), and each additional chlorine substltuent further lowers the reactiv-
ity of these compounds. Hydroxylatlons occur only at high temperatures In
1826A 3-1 03/22/84
-------
o
MONOCHLOAMENZENE
1. 2-OtCHI.O*O«NZENE 1.S-OICHLCWMENZENE 1.«-{MCHLOftOtEMZENE
O
o
1.2.a-TMICHlOftOVENZENE 1. 2.'-TftlCHLOAMENZENE 1.1. E-THICHlOHOtENZENE
O
o
p • o
1. 2. 1. 4-TETNACHLOACXENZENE 1. 2. 3. t-TETMACHLOHOCENZENE 1. 2, t. E-TETRACHIOMCWENZENE
o
FtNTACHLOftCWENZENE
NEXACHLOWMENZCNE
FIGURE 3-1
Chemical Structure of the Chlorinated Benzenes
1826A
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02/10/84
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TABLE 3-1
Synonyms, Trade Names and Identification Numbers of the Chlorinated Benzenes*
Chemical
Identification Number
Synonyms and Trade Names
Monochlorobenzene
CAS No. 108-90-7
TSL No. CZ017500
NCI No. C54886
EPA Haz Waste No.
EPA Haz Waste No.
U037
F002
Chlorobenzene
Benzene chloride
Phenyl chloride
Chlorobenzol
MCB
DOT Haz Mat No. UNI 134
Dlchlorobenzene
1,2-
CAS No. 95-50-1
TSL No. CZ4500000
NCI No. C54944
EPA Haz Waste No.
EPA Haz Waste No.
U070
F002
DOT Haz Mat No. UNI591
Chlorbenzene
Monochlorbenzene
Benzene, chloro-
Chlorobenzeen (Dutch)
Chlorobenzol
Chlorobenzene (Polish)
Clorobenzene (Italian)
Monochlorobenzene (Dutch)
Monochlorobenzol (German)
Monochlorobenzene (Italian)
o-D1chlorobenzene
o-D1chlor benzol
DCB
Dowtherm E
ODB
o-DCB
o-D1chlorobenzol
Orthodlchlorobenzene
Orthod1Chlorobenzol
Chloroben
Dlzene
Dlchlorobenzene, ortho, liquid
Special Termite Fluid
Term1tk1l
Cloroben
l,2-d1chloro-
o-d1chloro-
Benzene,
Benzene,
ODCB
Dllantln
DB
1826A
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03/22/84
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TABLE 3-1 (cont.)
Chemical
Identification Number
Synonyms and Trade Names
Dlchlorobenzene
1,3-
CAS No. 541-73-1
EPA Haz Waste No. U071
1,4-
CAS No. 106-46-7
TSL No. C24550000
NCI No. C54955
EPA Haz Waste No. U072
DOT Haz Mat No. UN1592
Benzene, m-d1chloro-
Benzene, 1,3-d1chloro-
m-Phenylene dlchlorlde
m-D1chlorobenzol
m~D1chlorobenzene
meta-D1ch1orobenzene
01-chlor1c1de
Paramoth
^-Dlchlorobenzene
PDB
Paradde
Paradlchlorobenzene
Paradl
Paradow
Santochlor
2-DCB
£-D1chlorobenzeen (Dutch)
1,4-D1chloorbenzeen (Dutch)
p_-D1chlorbenzol (German)
1,4-D1chlor-benzol (German)
j>-D1chlorobenzol
Dlchlorobenzene, para, solid
1,4-D1chlorobenzene (Italian)
p_-D1clorobenzene (Italian)
para Crystals
Paradlchlorobenzol
Paranuggets
Parazene
Benzene, f>-d1chloro-
Benzene, 1,4-d1chloro-
Pj-Chlorophenyl chloride
Evola
Persla-Perazol
1826A
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03/22/84
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TABLE 3-1 (cont.)
Chemical
Identification Number
Synonyms and Trade Names
Trlchlorobenzene
1,2,3-
Trlchlorobenzene
1,2,4-
1,3,5-
Tetrachlorobenzene
1.2,3,4-
1,2,3,5-
1,2.4,5-
Pentachlorobenzene
CAS No. 87-61-6
CAS No. 120-82-1
TSL No. DC2100000
CAS No. 108-70-3
CAS No. 634-66-2
CAS No. 634-90-2
CAS No. 95-94-3
TSL No. DB9450000
EPA Haz Waste No. U207
CAS No. 608-93-5
EPA Haz Waste No. U183
TSL No. DA6640000
y1c-Tr1chlorobenzene
1,2,6-Trlchlorobenzene
v-Tr1chlorobenzene
Benzene, 1,2,4-tr1chloro-
asym-Trlchlorobenzene
TCB
Trojchlorobenzen (Polish)
1,2,4-Tr1chlorobenzol
Hostetex L-Pec
s-Tr1chlorobenzene
sym-Tr1chlorobenzene
TCB
TCBA
Benzene, 1,3,5-tr1chloro-
Benzene, 1,2,3,4-tetrachloro-
Benzene, 1,2,3,5-tetrachloro-
Benzene tetrachlorlde
Benzene, 1,2,4,5-tetrachloro-
s-Tetrachlorobenzene
1,2,3,4,5-Pentachlorobenzene
QCB
Benzene, pentachloro-
Qulntochlorobenzene
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03/22/84
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TABLE 3-1 (cont.)
Chemical
Identification Number
Synonyms and Trade Names
Hexachlorobenzene
CAS No. 118-74-1
TSL No. DA2975000
EPA Haz Waste No. U127
Esaclorobenzene (Italian)
Amatln
Ant1car1e
Bunt-Cure
Bunt-No-More
Co-op Hexa
Granox NM
HCB
HEXA C.B.
Hexachlorobenzol (German)
Hexachlorobenzene
Julln's Carbon Chloride
No Bunt
No Bunt 40
No Bunt 80
No Bunt Liquid
Pentachlorophenyl Chloride
Perchlorobenzene
Phenyl Perchloryl
Sanodde
Smut-Go
Snledotox
*Source: National Library of Medicine (NLM), Toxicology Data Bank (TDB)
1826A
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03/22/84
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TABLE 3-2
CD
CT>
Chemical
Monochlorobenzene
Dlchlorobenzene
1.2-
1.3-
1.4-
Trlchlorobenzene
1.2,3-
1.2,4-
1.3,5-
Vs Tetrachlorobenzene
-J 1.2.3,4-
1.2,3,5-
1.2.4,5-
Pentachlorobenzene
Hexachlorobenzene
Molecular
Weight
112.56
147.01
147.01
147.01
181.46
181.46
181.46
215.90
215.90
215.90
250.34
284.76
Melting
Point
CC)
-45.6
-17.0
-24.7
53.1
52.6
16.95
63.4
47.5
54.5
139.5
86
230
Physical
Boiling
Po1ntb
CC)
132
180.5
173
174
221
213.5
208.4
254
246
246
277
3229
Properties of
Density0
(g/mt)
1.1
1.30
1.28(25)
1.25
1.69
1.45
1. 39(64)1"
NA
NA
1.86(22)
1.83(16.5)
1.57(23)
the Chlorinated Benzenes3
Henry's Law
Constant11 x 10"
(a tin m3 mol M
2.6
1.3
2.4
1.0
4.3
0.12
Log P°d
2.84*
3.38*
3.38f
3.39f
4.]1,J
4.121
NA
NA
NA
4.933."
5.63"
5.81
Water
Solubility
(rag/l)*
500(20)9
1459
1239
799
31. 5k
34. 6k
6.6k
4.3k
3.5k
0.60k
0.56k
0.005k
Flash
Point
(°C or °F)
85 F/cc"
151 F/cc
NA
150 F/cc
113 C
110 C
107 C
NA
311 F
311 F
NA
468 F
Index of
Refraction
at CC)
1.5241(20)
.5515(20)
.5459(20)
.5285(60)
.5776(19)
.5717(20)
.5662(19)
NA
NA
NA
NA
NA
o
to
CO
Data are from the National Library of Medicine (NLM), Toxicology Data Bank (TDB), except as noted.
bAt 760 mm
°At 20"C, except as noted
dMacKay et al.. 1979
eAt 25°C, except as noted
fLeo et al., 1971
9Verschueren, 1977
These are data from closed cup (cc) experiments
Monsanto, 1978
^Isomer unspecified
kYalkowsky and Valvanl, 1980
Hansch and Leo, 1981
"Wrvath, 1982
nU.S. EPA. 1980b
P° = Partition coefficient at 25°C
NA = Not available
-------
TABLE 3-3
Vapor Pressures and Vapor Densities of the Chlorinated Benzenes
Chemical
Vapor Pressure
(mm Hg)
Specific Vapor Density
(air = 1)
Monochlorobenzene
Dichlorobenzene
1.2-
1,3-
1,4-
Trlchlorobenzene
1,2,3-
1,2,4-
1,3,5-
Tetrachlorobenzene
8.8 at 20°Ca
10 at 22.2°Cb
11.8 at 25°Cb
15 at 30°Ca
1 at 20°Ca
1.28 at 25°Ce
1.5 at 25°Ca
1.9 at 30°ca
1 at 12.1°Cb
1.89 at 25°Cd
0.6 at 20°Ca
1.0 at 25°Cf
1.8 at 30°Ca
0.07 at 25°Cd
1 at 40°Cb
0.29 at 25°Cd
1 at 38.4°Cb
0.15 at 25°Cd
10 mm at 78°Cb
3 88a,b,c
3.9d
5.05b
5.07a»c
5.08°
5.07C
5.08b
6.26b
6.26b
6.26b
1,2,3,4-
1,2,3,5-
1,2,4,5-
1 at 68.5°C9
0.04 at 25°Ch
1 at 58.2°C9
0.07 at 25°Ch
0.05 at 25°C1
0.05 at 25°Ch
NA
NA
7.4b
1826A
3-8
03/22/84
-------
TABLE 3-3 (cont.)
Chemical Vapor Pressure Specific Vapor Density
(mm Hg) (air = 1)
Pentachlorobenzene 1 at 98.6°C9 NA
Hexachlorobenzene 1 at 114°C9 9.84a
1.68xlO~5 at 25°CJ
1.089xlO"5 at 20°Ck
aVerschueren, 1977
bSax, 1979
Clowenhe1m and Moran, 1975
dNLM, 1982a
eR1chardson, 1968
fMart1n and Worthing, 1977
9Weast, 1980
"MacKay et al., 1982
1Ware and West, 1977
^Leonl and Oarca, 1976
kFarmer et al., 1980
NA = Not available
1826A 3-9 03/22/84
-------
very alkaline conditions. A description of each of the chlorinated benzenes
follows.
Monochlorobenzene, which 1s the most polar of the chlorinated benzenes,
1s a colorless, volatile liquid with a pleasant almond-like odor that 1s
classified as a flammable liquid by the U.S. Department of Transportation
(NLM, 1982a). Monochlorobenzene 1s soluble 1n water to the extent of 499+8
mg/S, at between 20 and 30°C (Verschueren, 1977). It 1s mlsdble 1n all
proportions 1n ethyl alcohol and dlethyl ether, and 1s very soluble 1n car-
bon dlsulflde and benzene (NLM, 1982a). No established trade specifications
exist for monochlorobenzene. Kao and Pottenberger (1979) reported two
Impurities for a typical analysis of monochlorobenzene: dlchlorobenzenes at
<0.1 wt percent and benzene at <0.05 wt percent. This Implied a purity of
99,Q% or higher for the sample. A product data sheet (Dow Chemical Company,
1977) listed a 99.9% purity for monochlorobenzene, while Allied Chemical
Corporation (1973) stated a purity of 99.0% for Us product (U.S. EPA, 1980a)
1,2-D1chlorobenzene 1s a clear, volatile liquid with a pleasant odor
(NLM, 1980) and 1s combustible at room temperature. It has a solubility of
145 mg/8, 1n water at 25°C (Verschueren, 1977). 1,2-D1chlorobenzene 1s
mlsdble with alcohol, ether, benzene, carbon tetrachlorlde, and acetone
(NLM, 1980). The lack of Industry-wide standards of purity for this chlori-
nated benzene 1s Illustrated by the compositions reported for 1,2-d1chloro-
benzene by different sources shown 1n Table 3-4.
1,3-D1chlorobenzene 1s a colorless liquid that 1s combustible at room
temperature. It can react violently with aluminum (NLM, 1981a). It has a
solubility of 123 mg/a, 1n water at 25°C (Verschueren, 1977). 1.3-D1-
chlorobenzene 1s soluble 1n alcohol, ether and benzene, and 1s mlsdble with
acetone, carbon tetrachlorlde and petroleum ether (NLM, 1981a).
1826A 3-10 03/22/84
-------
00
PO
cr<
3*
CO
1
— '
0
o
CO
TABLE 3-4
Reported Composition of Commercial 1 ,2-01ch1orobenzene
Composition (%}
Constituent Standard Standard Mechanical High Purity Technical
Grade3 Gradeb Gradec Grade0 Graded
C6H5C1 NA 0.07 NA NA <0.05
1,2-C6H4C12 80 82.7 75-85 99.0 80.0
1,3-C6H4C12 2 0.5 0.5 "balance" <19.0
1,4-C6H4C12 17 15.4 15-25 NA NA
C6H3C1 (all Isomers) NA 1.6 NA NA <1.0
1.2.4-C6H3C13 NA NA NA NA NA
aDow Chemical Company, 1977
bAH1ed Chemical Company, 1973
CMCA, 1974
dKao and Poffenberger, 1979
NA = Not available
Purified
Graded
<0.05
98.0
NA
NA
NA
<0.2
-------
1,4-D1chlorobenzene 1s a combustible crystalline solid that tends to
sublime at ordinary temperatures. It possesses a distinctive odor that 1s
noticeable at concentrations between 30 and 60 ppm (NLM, 1981a). It has a
solubility of 79 mg/t 1n water at 25°C (Verschueren, 1977). It 1s soluble
at 25°C 1n ether, chloroform, carbon dlsulflde and benzene, and 1s mlsdble
with alcohol and acetone (NLM, 1981b). The commercially available technical
grade 1,4-d1chlorobenzene may contain <0.5 wt percent of the other two
Isomers and also may contain <0.1 wt percent of monochlorobenzene and
trlchlorobenzene (Kao and Poffenberger, 1979). A product data sheet (Dow
Chemical Company, 1977) stated a purity of 99.95% for that company's 1,4-
dlchlorobenzene. Product Information from Montrose Chemical (1972)
described a mixture of 35% 1,2-d1chlorobenzene and 65% 1,4-d1chlorobenzene
(U.S. EPA, 1980a).
1,2,3-TMchlorobenzene 1s a white crystalline solid (platelets from
alcohol) that 1s volatile with steam. It 1s slightly soluble (31.5 mg/st)
at 25°C 1n water, slightly soluble In alcohol, soluble 1n benzene and carbon
dlsulflde, and very soluble 1n ether (NLM, 1981e; Yalkowsky and Valvanl,
1980).
1,2,4-Trlchlorobenzene 1s a colorless liquid at 25°C but may also take
the form of rhombic crystals because of Its low melting point of 16.95°C.
It possesses a distinctive odor, similar to that of 1,4-dlchlorobenzene, and
1s considered volatile with steam (NLM, 1981f). It 1s slightly soluble 1n
water, 34.6 mg/8, at 25°C {Yalkowsky and Valvanl, 1980); mlsdble with
benzene, petroleum ether and carbon dlsulflde; slightly soluble 1n ethanol;
and very soluble 1n dlethyl ether (NLM, 198lf). An Information sheet (Dow
Chemical Company, 1977) listed a purity of 100% for Its product. Kao and
Poffenberger (1979) reported that commercial 1,2,4-tr1chlorobenzene may
1826A 3-12 03/22/84
-------
contain monochlorobenzene (<0.1 wt percent) and d1- and tetrachlorobenzenes
(<0.5 wt percent and <0.5 wt percent) with the 1,2,4-tr1ch1orobenzene
content being around 97X.
1,3,5-TMchlorobenzene takes the physical form of white crystals or
needles. It 1s very slightly soluble (6.6 mg/8, at 25°C) 1n water; spar-
ingly soluble In alcohol; and soluble 1n ether, benzene, petroleum ether,
carbon dlsulflde and glacial acetic add (NLM, 1982c; Yalkowsky and Valvanl,
1980).
1,2,3,4-Tetrachlorobenzene 1s a white crystalline solid that appears as
needles from alcohol (NLM, 1981c). It 1s very slightly soluble In water
(4.3 mg/a at 25°C); slightly soluble 1n alcohol; soluble 1n hot alcohol;
and very soluble 1n ether, carbon dlsulflde, acetic add and petroleum ether
(NLM, 1981c; Yalkowsky and Valvanl, 1980).
1,2,3,5-Tetrachlorobenzene 1s a solid that appears 1n the form of
needles or white flakes. It 1s very slightly soluble 1n water (3.5 mg/si
at 25°C), slightly soluble 1n alcohol, and very soluble 1n carbon dlsulflde
and petroleum ether (NLM, 1981d; Yalkowsky and Valvanl, 1980).
1,2,4,5-Tetrachlorobenzene appears as white flakes or needles. It takes
the form of monocl1n1c prisms from ether, alcohol or benzene. It 1s
practically Insoluble 1n water (0.6 mg/fc at 25°C), slightly soluble 1n hot
alcohol, and soluble 1n ether, chloroform and carbon dlsulflde (NLM, 1982b;
Yalkowsky and Valvanl, 1980). A commercial 1,2,4,5-tetrachlorobenzene was
analyzed as 97.0% pure; Impurities were not Identified (Kao and Potten-
berger, 1979; Dow Chemical Company, 1977).
Pentachlorobenzene 1s a needle-like solid (NLM, 1979b). It Is slightly
soluble 1n water (0.56 mg/!i at 25°C); slightly soluble 1n ether, benzene
and chloroform; and soluble 1n hot alcohol and carbon dlsulflde (NLM, 1979b;
Yalkowsky and Valvanl, 1980).
1826A 3-13 03/22/84
-------
Hexachlorobenzene is a colorless crystalline (rnonocllnic prisms) solid.
Its water solubility was reported as 0.005 mg/8, at 25°C (Yalkowsky and
Valvani, 1980). Hexachlorobenzene 1s sparingly soluble 1n cold alcohol and
soluble 1n benzene, chloroform and ether (NLM, 1979a). Impure commercial
preparations may contain pentachlorobenzene (10-81,000 ppm), octachlorodi-
benzo-p-d1ox1n (0.05-212 ppm) and octachlorodlbenzofuran (0.35-58.3 ppm)
(VUleneuve et al., 1974).
According to the CRC Atlas of Spectral Data and Physical Constants for
Organic Compounds (Grasselll, 1973) the following group trends 1n spectro-
scoplc properties can be seen:
There is a red shift 1n ultraviolet xmax for the aromatic
•a to ir* transition with Increasing chlorination (245 to 272 nm
for monochlorobenzene; 291 to 301 nm for hexachlorobenzene). This
Implies that the more chlorinated the chlorinated benzene, the more
likely 1s photodegradatlon at sea level by sunlight. Diagnostic
Infrared absorptions for all the chlorinated benzenes occur around
3.2-3.3 and 6.2-6.4 vm. All the proton NMR aromatic signals for
chlorinated benzenes 1n carbon tetrachloride or deuterated chloro-
form solvents occur between 6.9 to 7.5 ppm with respect to tetra-
methylsllane. The mass spectra for all compounds are characterized
by very Intense molecular Ions (M) (100% for all compounds except
for pentachlorobenzene), and Intense M-35 peaks. Thus, specific
1on monitoring using the molecular Ions and M-35 peaks 1s possible,
Increasing the sensitivity of analysis.
The atmospheric chemistry of chlorobenzenes has been studied
under laboratory conditions. Oilling et al. (1976) studied the
photocatalzyed degradation of monochlorobenzene in an atmosphere
containing 5 ppm nitric oxide and reported its half-life to be 8.7
hours under strong light at room temperature. Kanno and Nojima
(1979) irradiated monochlorobenzene with light from a xenon lamp in
the presence of nitric oxide and air and found the products to be
chlorinated n1trobenzenes and nltrophenols. Uyeta et al. (1976)
found that Irradiation of several chlorobenzenes with natural sun-
light for periods up to 56 days yielded polychlorlnated biphenyls.
Whether PCBs are formed under atmospheric conditions is unknown,
but unlikely because of the low concentration. Yanagihari et al.
(1977) studied the degradation of monochlorobenzene in a smog cham-
ber (2 ppm chlorobenzene, 1 ppm NOX) and found 7.5% degradation
in 5 hours. Using higher concentrations (5000 ppm chlorobenzene
and 1000 ppm NO), Kanno and Nojima (1979) found similar rates of
degradation and identified one chloronitrobenzene and three
chloronitrophenols as products. Rates of reaction of chlorobenzene
with hydroxyl radical (Anbar and Neta, 1967) and singlet oxygen
1826A 3-14 03/22/84
-------
(Graedel, 1978) are also available which allows half-life estima-
tions of 0.5 and 2.6 years, respectively. Yanohlhara et al. (1977)
also studied the atmospheric photochemistry of o-d1chlorobenzene
and found 21.5% degradation 1n 5 hours and Nojlma and Kanno (1980)
found 7.6% of p_-d1chlorobenzene (high concentrations of test chemi-
cal and NO) 1n 5 hours of Irradiation.
One study has examined the possibility of photocatalyzed
degradation of the chlorinated benzenes. Oliver et al. (1979)
exposed 1.4 dlchlorobenzene 1n saturated aqueous solutions with
various suspended sediments (titanium oxide, clays and samples of
river sediments) to ultraviolet light. Degradation of the dlchlo-
robenzene occurred only 1n the titanium oxide solution, possibly
because of a shielding of the chemical from the light by the other
sediments or a catalytic effect of titanium oxide, and did not
occur 1n natural sediment systems. Korte et al. (1978) and Hustert
et al. (1981) demonstrated that hexachlorobenzene was photocheml-
cally stable. The Hustert et al. (1981) study consisted of sun-
light Irradiation of an aqueous solution.
3.3. ANALYTICAL METHODOLOGY
The usual sampling and analytical methods for airborne chlorobenzenes
Involve the adsorption and concentration of airborne vapors on sorbentpacked
cartridges followed by thermal desorptlon and gas chromatographlc (GC) anal-
ysis using either flame 1on1zat1on detection, electron capture detection, or
photo1on1zat1on detection. The purge and trap method 1s the most common
method used for the sampling of volatile chlorobenzenes 1n water. Headspace
analysis using GC with flame 1on1zat1on detection or electrolytic conductiv-
ity detection are also used for analysis of aqueous samples. Methods that
are slightly modified from the analytical procedures for aquatic samples are
used for the analysis of chlorobenzenes 1n soil, food and human tissues.
The following sections provide examples of these analytical methods.
3.3.1. Analysis 1n A1r. Krost et al. (1982) described a method whereby
ambient air was drawn through a cartridge containing a 1.5x6.0 cm bed of
Tenax-GC (35/60 mesh) so that vapors were collected completely on the resin.
The sample was then thermally desorbed and the vapors passed through a cryo-
genlcally cooled trap and subsequently Introduced Into a gas chromatograph-
1826A 3-15 03/22/84
-------
mass spectrometer (GC-MS). Estimated detection limits for three chloroben-
zenes were as follows: monochlorobenzene, 2.1 ng/m3; 1,2-d1chlorobenzene,
1.0 ng/m3; and 1,3-d1chlorobenzene, 0.7 ng/m3. However, the precision
of this method for field sampling and analysis has been determined to range
from flO to 4-40% relative standard deviation. A similar method has been
used for the monitoring of mono- and dlchlorobenzenes by Barkley et al.
(1980), PelllzzaM (1982) and Bozzelll (1981).
Lewis and MacLeod (1982) have developed and evaluated a portable low-
volume air sampling system for Indoor air monitoring of semlvolatlle organic
chemicals. Two types of sampling cartridges were used to sample for chloro-
benzenes. Using polyurethane foam (PUF), a mean collection efficiency of
94.0% with a relative standard deviation of 12% was determined for five
1 vg samples of pentachlorobenzene. For five 0.5 and 1.0 yg samples of
hexachlorobenzene, the reported mean collection efficiency was 94.5% with a
relative standard deviation of 8%. The tr1- and tetrachlorobenzenes were
poorly trapped using this PUF plug, with collection efficiencies of 6.6 and
62.3%, respectively. However, using a dual-sorbent trap consisting of a
0.6 g layer of Tenax-GC (35-60 mesh) sandwiched between two 3.8 cm PUF
plugs, a collection efficiency of 98% was obtained for both compounds.
Theoretical detection limits, using GC-electron capture detection, are
expected to be at least one order of magnitude lower (1n the range of
0.06-0.1 ng/m3). Storage stability of the PUF cartridges was tested
under adverse storage conditions. The amount of chlorobenzenes recovered
from the cartridges after 15 days of storage at 32°C ranged from 57% for the
trichlorobenzenes to 98% for hexachlorobenzene. Billings and Bldleman
(1980) reported that hexachlorobenzene was very poorly retained by porous
3-16 03/22/84
-------
PUF, but efficiently collected by Tenax-GC. Oehme and Stray (1982), how-
ever, reported high recovery (76-115%) of tr1-, tetra-, penta- and hexa-
chlorobenzene with PUF plugs.
Langhorst and NestMck (1979) used an air sampling tube packed with two
sections of Amberllte XAD-2 resin separated by a sllanlzed glass wool plug
to collect the chlorobenzenes. The adsorbent was desorbed with carbon
tetrachlorlde and analyzed by GC using a photo1on1zat1on detector. Using
the method described, the minimum detection limits for mono-, d1-, trl-,
tetra-, penta- and hexachlorobenzene were 15, 20, 30, 35, 45 and 70 ppb
(v/v), respectively. Collection and desorptlon efficiencies for all chloro-
benzenes (air concentrations between 5 ppb and 15 ppm) were ~95% with a
precision of +02%.
Thompson et al. (1980) described a sampling technique using the Trace
Atmospheric Gas Analyzer coupled with negative atmospheric pressure chemical
1on1zat1on for analysis of hexachlorobenzene after gas chromatography. This
system 1s portable with close to real-time capability and a detection limit
of -30 ppt (v/v) 1n air.
Van Tassel et al. (1980) pointed out that there are disadvantages 1n
using some sorbent materials because of Interferences, such as relative
humidity and high concentrations of carbon dioxide. They described a method
for determining m1crogram-per-cub1c meter levels of monochlorobenzene 1n air
using sampling cartridges containing Porapak N, followed by elutlon with
methanol and analysis by GC. Both electron capture detection and photo-
1on1zat1on detection can be used with detection limits of 1 yg/m3 and 5
vg/m3, respectively. This technique reportedly allows for greater
flexibility. Results are reproducible at various relative humidity levels
and varying concentrations of carbon dioxide. Advantages over thermal
1826A 3-17 03/22/84
-------
desorptlon techniques Include ease of operation and the ability to use
various columns to achieve analytical precision.
NIOSH (1977) has developed sampling and analytical methods for occupa-
tional air monitoring for monochlorobenzene, 1,2-d1chlorobenzene and 1,4-
dlchlorobenzene. All three methods Involve trapping the compound 1n a char-
coal tube, desorblng the analyte with carbon dlsulflde, and analyzing the
sample 1n a gas chromatograph using flame 1on1zat1on detection.
3.3.2. Chemical Analysis 1n Wattr. The purge-trap method 1s the most
commonly used method for analyzing volatile organlcs 1n water. Otson and
Williams (1982) evaluated the use of the dynamic headspace or the purge-trap
method 1n combination with GC technique for a number of organlcs Including
monochlorobenzene and dlchlorobenzene. For monochlorobenzene, a recovery
rate of 91% was measured using flame 1on1zat1on detection and 96% was mea-
sured using electrolytic conductivity detection. The corresponding recovery
rates for 1,4-d1chlorobenzene were 65 and 58%. Detection limits ranged from
<0.1 pg/8, for monochlorobenzene to 0.2 vq/i for 1,2-d1chlorobenzene.
The relative standard deviation ranged from 6.3-9.6% using flame 1on1zat1on
detection. Storage of samples for several weeks did not affect results by
more than ^15%. The dynamic headspace or the purge-trap method has been
used by other researchers to determine the levels of mono- and dlchloroben-
zenes 1n water samples (Perelra and Hughes, 1980; Jungclaus et al., 1978).
The purge-trap technique 1s also recommended by U.S. EPA Method 602 (1982)
for the determination of mono- and dlchlorobenzenes 1n wastewater. Cowen
and Baynes (1980) concluded that headspace analysis was applicable for
monochlorobenzene and dlchlorobenzenes, using flame 1on1zat1on detection at
the 5 yg/9. concentration 1n water. Minimum detectable quantities using
electrolytic conductivity detection were 0.15 and 0.20 ng for monochloro-
1826A 3-18 03/22/84
-------
benzene and dlchlorobenzenes, respectively. The static headspace technique
was employed by Otson et al. (1982) for the quantification of mono- and
dlchlorobenzene 1n Canadian potable waters.
The purge-trap technique does not provide quantitative recoveries for
compounds with low volatilities, such as trlchlorobenzenes and higher
chlorinated benzenes. Therefore, a solvent extraction and cleanup method 1s
normally used to produce organic extracts suitable for GC/MS analysis. The
U.S. EPA (1982) (Method 612) has recommended the use of Flor1s1l column
chromatography as a cleanup step before the quantification of the samples by
GC with electron capture detector. This recommended method Is applicable
for the determination of d1-, tr1-, tetra-, penta- and hexa-chlorobenzene In
drinking water and wastewater. The recovery of dlchlorobenzenes and hexa-
chlorobenzene by this method was found to be 82-89% and 95%, respectively.
The percent standard deviation of the method for dlchlorobenzenes and
hexachlorobenzene ranged from 10-20% (U.S. EPA, 1982).
3.3.3. Chemical Analysis 1n Soil, Sediment and Chemical Waste Disposal
Site Samples. A method for the determination of hexachlorobenzene 1n soil
and chemical waste disposal site samples has been developed by DeLeon et al.
(1980). The procedure Involves methane extraction followed by temperature-
programmed GC analysis using electron capture detection. Recoveries of
samples spiked at the 10, 100 and 300 vg levels were 96.5% (±3.6), 93.1%
(±8.1) and 78.0% (±2.6), respectively. The lower detection limit for this
method 1s around 10 yg/g. The solvent extraction method was used by
Lopez-Avlla (1983) to determine chlorobenzenes 1n sediment samples. In this
method, the solvent extract was subjected to acid-base fractlonatlon. The
base/neutral fraction containing the chlorobenzenes was fractionated by
silica gel chromatography. The final separation and quantification was
1826A 3-19 03/22/84
-------
accomplished by GC-MS. The recovery of 1,3-dichlorobenzene, 1 ,?-d1chloro~
benzene, 1,2,4-tr1chlorobenzene and hexachlorobenzene by this method was 63,
66, 67 and 46%, respectively, at a spike level of 400 ng/g of dry sediment.
3.3.4. Chemical Analysis 1n F1sh and Other Foods.
3.3.4.1. FISH -- The levels of pentachlorobenzene and hexachloroben-
zene have been determined 1n fish samples using solvent extraction, solvent
and sulfurlc add partitioning and GC with electron capture detection (Lunde
and Ofstad, 1976).
H1att (1981) compared three analytical methods used to quantify mono-
chlorobenzene levels 1n fish tissue. His data Indicate that recoveries of
64^15%, 32+8%, and 68% were reported for the vacuum extraction method,
direct purge and trap method, and a modified purge and trap method, respec-
tively. In the modified purge and trap procedure, the homogenized fish
tissue was purged, with the concentration trap Immersed 1n an 1ce water bath
for 5 minutes, followed by Immersion 1n a 55°C water bath for an additional
7 minutes. This modification provided reproducible purging efficiencies. A
similar modified purge-trap method has been used by Easley et al. (1981) for
the determination of monochlorobenzene 1n fish samples.
The determination of trlchlorobenzenes and other higher chlorinated
benzenes 1n fish samples can also be done by a solvent extraction method.
In one method, Kuehl et al. (1980) subjected the solvent extract to Flor1s1l
and gel permeation on chromatographlc separation, followed by GC-MS Identi-
fication and quantification of tMchlorobenzene and other higher chlorinated
benzenes 1n fish samples. Murray et al. (1980), however, used solvent
partitioning, silica gel chromatography, followed by GC-electron capture
detection for the quantification of hexachlorobenzene 1n fish samples.
1826A 3-20 03/22/84
-------
3.3.4.2. HUMAN MILK -- A method to detect ppb concentrations of hexa-
chlorobenzene 1n human milk has been used by Brevlck (1978). This method
Involves solvent extraction and GC analysis using electron capture detec-
tion. A mean recovery of 98.6+10.8% was reported for 10 samples containing
5 ppb hexachlorobenzene. The solvent extraction method was also used by
Tessarl and Savage (1980) for the determination of hexachlorobenzene 1n
human milk. In this method, the extract was subjected to Flor1s1l and
silica gel column chromatographlc cleanup, followed by GC-electron capture
detection. The method gave 68% recovery at a fortification level of
5.7 ng/g.
The quantification of more volatile halogenated benzenes, such as mono
and dlchlorobenzenes In milk samples, was performed by a purge and trap
technique at an elevated temperature of 50°C. The trapped gas was thermally
desorbed and quantified by the GC-MS method (Michael et al., 1980). The
average recovery of monochlorobenzene by this method was determined to be
88%.
3.3.4.3. OTHER FOODS — R1ce, vegetables, meat, milk, eggs and fish
have been analyzed for hexachlorobenzene residues using GC with electron
capture detection (SekHa et al., 1980); GC-MS was used to confirm the anal-
ysis. A similar solvent extraction method, followed by solvent partitioning
and Flor1s1l column cleanup, and GC-electron capture detection was used for
the quantification of hexachlorobenzene in different crops from 37 states
(Carey et al., 1979).
3.3.4.4. OTHER BIOLOGICAL MATRICES -- Gas chromatography using elec-
tron capture detection has been employed to determine levels of pentachloro-
benzene and hexachlorobenzene In blood samples (Lunde and Bjorseth, 1977)
and to determine levels of 1,4-dichlorobenzene and Us major metabolites 1n
1826A 3-21 03/22/84
-------
urine and serum samples (McKlnney et al., 1970). Blood and urine samples
have also been analyzed for the chlorobenzenes by GC using photolonlzatlon
detection (Langhorst and Nestrlck, 1979). Using carbon tetrachloride
extraction, silica gel column chromatography and concentration with a
Kuderna-Danlsh concentrator, chlorobenzene recoveries from blood and urine
samples averaged 83^12% for concentrations between 1 and 500 ppb.
A method of hexachlorobenzene determination and confirmation 1n adipose
tissue has been described by Watts et al. (1980). In this method, the
solvent extract 1s subjected to a Flor1s1l cleanup and one-fraction elutlon.
Hexachlorobenzene 1s determined by direct GC with electron capture detec-
tion. Confirmation 1s made by analysis of the b1s-1sopropoxytetrachloroben-
zene derivative, which 1s formed by reaction with Isopropanol. Average
recoveries ranged between 87.4i6.8% and 92.&ilO.O%. This method 1s particu-
larly useful for the determination of hexachlorobenzene 1n the presence of
M1rex.
The determination of the less volatile chlorinated benzenes, such as
tr1-, tetra-, penta- and hexachlorobenzene 1n biological tissue samples, has
been done by solvent extraction of the tissue, followed by column chromato-
graphlc cleanup of the sample and final separation and quantification by GC
with electron capture detection (Lamparskl et al., 1980; Mes et al., 1982).
For more volatile chlorinated benzenes, such as mono- and dlchlorobenzenes,
the modified purge-trap method 1n combination with capillary GC and flame
1on1zat1on detection or preferably more specific detection method can be
used (Michael et al., 1980).
1826A 3-22 03/22/84
-------
3.4. SUMMARY
The chlorinated benzenes are a group of compounds 1n which 1-6 chlorine
substltuents have been added to a benzene ring yielding a total of 12 1so-
merlc forms. In general, these compounds have low water solubility (solu-
bility decreasing with Increasing chlorlnatlon), low flammabllHy, moderate
to high octanol/water partition coefficients (coefficients Increasing with
Increasing chlorlnatlon) and low to moderate vapor pressures (vapor pres-
sures decreasing with Increasing chlorlnatlon). They are chemically unreac-
tlve and exist as liquids or solids at environmental conditions. Analysis
of airborne chlorobenzenes 1s usually accomplished by adsorption onto
sorbent cartridges, followed by thermal desorptlon and analysis by GC. For
water samples, the purge-trap method 1s used to concentrate the volatile
halogenated benzenes before analysis by GC. For less volatile chlorinated
benzenes, solvent extraction followed by column chromatographlc cleanup of
the extract and GC with electron capture detection, 1s the most commonly
used method for the Isolation, detection and quantification. Methods
similar to those used for wastewater samples are commonly used for the
analysis of chlorinated benzenes 1n biological matrices.
1826A 3-23 03/22/84
-------
4. PRODUCTION, USE AND ENVIRONMENTAL LEVELS
4.1. PRODUCTION
Industrial synthesis of chlorinated benzenes 1s achieved through the
controlled catalytic chlorlnatlon of benzene and 1s described 1n the K1rk-
Othmer Encyclopedia of Chemical Technology (Hardle, 1964). In general,
monochlorobenzene and the dlchlorobenzenes are synthesized at 30-50°C 1n the
presence of a ferric chloride catalyst. The output 1s then purified by
distillation, and the Isomers are Isolated by fractional distillation or
crystallization. Trlchlorobenzene 1s produced by the chlorlnatlon of
dlchlorobenzene using ferric chloride and temperatures of 25-30°C. An
aluminum catalyst, trlchlorobenzene and chlorine are used to produce tetra-
chlorobenzene, which 1n turn can serve as a precursor for pentachloroben-
zene. Hexachlorobenzene can be obtained by the chlorlnatlon of benzene at
150-200°C using a ferric chloride catalyst or from the distillation of resi-
dues from the production of tetrachloroethylene. Because these reactions
are not completely controlled and purification processes are not 100% effec-
tive, 1t 1s likely that any commercially available chlorinated benzene will
also contain unwanted IsomeMc chlorobenzenes as Impurities, and this 1s
particularly true for 1,2-d1chlorobenzene.
The TSCA Inventory (U.S. EPA, 1981) provides production data on the
chlorinated benzenes for Individual facilities. The data for the largest
producers (>lx!06 pounds/year) are expressed as ranges of estimated pro-
duction for 1977 1n Table 4-1. Total yearly production data are published
for high-volume, synthetic chemical Intermediates by the U.S. International
Trade Commission (USITC); data for 1980 are available only for monochloro-
benzene, 1,2-d1chlorobenzene and 1,4-d1chlorobenzene (USITC, 1981), and are
1827A 4-1 02/13/84
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TABLE 4-1
United States Production of Chlorinated Benzenes for Selected Years
Chemical/
Manufacturers
Location
Production
Estimates
for 197?a
(Ib x 106)
Production
for 1980b
(Ib x 10«)
Monochlorobenzene:
Dow Chemical Co.
PPG Industries, Inc.
Montrose Chemical
Corp. of CA
Allied Chemical Corp.
Monsanto Co.
NAd
NAd
1,2-D1chlorobenzene:
Dow Chemical Co.
PPG Industries, Inc.
Monsanto Co.
Montrose Chemical
Corp. of CA
Allied Chemical Corp,
1,3-D1ch1orobenzene:
PPG Industries, Inc.
NAd
Midland, MI 50-100
New Mart1nsv1lle, WV 10-50
Henderson, NV 10-50
Solvay, NY 1-10
Sauget, IL 50-100C
NAd 10-50
NAd 1-10
Total: 132-370
Midland, MI 1-10
New Mart1nsv1lle, WV 10-50
Sauget, IL 1-10
Henderson, NV 1-10
Solvay, NY 1-10
Total: 14-90
New Mart1nsv1lle, WV 0.1-1
NAd 0.1-1
Total: 0.2-2
284
49
NA
1827A
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03/22/84
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TABLE 4-1 (cont.)
Chemical/
Manufacturers
1 ,4-D1chlorobenzene:
Dow Chemical Co.
PPG Industries, Inc.
Monsanto Co.
Montrose Chemical
Corp. of CA
Allied Chemical Corp.
Dover Chemical Corp.
NAd
1 ,2, 3-Tr1chlorobenzene:
Dow Chemical Co.
1 ,2,4-TMchlorobenzene:
Dow Chemical Co.
NAd
1 ,3,5-TMchlorobenzene:
Chemical Systems Division
1 ,2,3,4-Tetrachlorobenzene:
Dow Chemical Co.
NAd
Production
Location Estimates Production
for 1977a for 1980b
(Ib x 10s) (Ib x 106)
Midland, MI
New Mart1nsv1lle, WV
Sauget, IL
Henderson, NW
Solvay, NY
Dover, OH
NAd
Total:
Midland, MI
Total:
Midland, MI
NAd
Total:
San Jose, CA
Total:
Midland, MI
NAd
Total:
1-10
10-50
1-10
1-10
1-10
1-10
1-10
16-110
1-10
1-10
1-10
10-50
11-60
0.01-0.1
0.01-0.1
1-10
0.1-10
1.1-20
75
NA
NA
NA
NA
1827A
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03/22/84
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TABLE 4-1 (cont.)
Chemical/
Manufacturers
1 ,2,3,5-Tetrachlorobenzene:
(No manufacturers listed)
1 ,2,4,5-Tetrachlorobenzene:
Dow Chemical Co.
Chem South Corp.
NAd
Pentach lorobenzene:
Ol1n Corp.
Hexachlorobenzene:
(No manufacturers listed)
Production
Location Estimates Production
for 1977a for 1980b
(Ib x 10*) (Ib x 106)
Midland, MI 10-50
ChUdersburg, AL 0.1-lc
NAd 1-1 Oc
Total: 11.1-61 NA
Mclntosh, AL 1-10
Total: 1-10 NA
NA
aSource: U.S. EPA, 1981
bSource: U.S. ITC, 1981
CA11 production at this site was processed within the facility and was not
distributed outside the facility as a chemical or 1n a mixture.
dProducer and location not listed in the TSCA inventory.
NA = Not available
1827A
4-4
03/22/84
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Incorporated Into Table 4-1. A more recent 11st of producers and the esti-
mates of their production capacities for chlorobenzenes are available from
SRI (1983), who 11st the producers of chlorobenzenes and their estimated
production capacities as of January 1983 (Table 4-2). The names of the
chlorobenzene manufacturers given 1n Table 4-2 are slightly different from
those given 1n Table 4-1, because Table 4-2 11st only the manufacturers as
of January, 1983.
As mentioned already, hexachlorobenzene 1s not manufactured commercially
1n the United States but does occur 1n waste streams during the production
of some organic chemicals (e.g., perchloroethylene, trlchloroethylene,
carbon tetrachlorlde and chlorine) and pesticides.
4.2. USE
Chlorinated benzenes are used 1n manufacture of Intermediates 1n the
production of organic chemicals, Including other chlorinated benzenes,
herbicides, pesticides, dyes and rubber chemicals and as dye carriers,
process solvents, pesticides, fungicides and deodorizing agents (U.S. EPA,
1980). A summary of these uses 1s presented 1n Table 4-3.
4.3. SOURCE AND ENVIRONMENTAL LEVELS
No comprehensive studies have been conducted on the sources of chloro-
benzenes released Into the environment. In general, these releases would
occur during the manufacture and transport of chlorobenzenes, through their
use as pesticides, solvents and other Industrial and comsumer products, and
through the disposal of wastes from the manufacturing process. Estimates of
releases (Table 4-4) have been made for monochlorobenzene, dlchlorobenzenes
and trlchlorobenzenes. Dow (1978) estimated that 30-50% of the monochloro-
benzene produced annually was released Into the air. Virtually all the
monochlorobenzene used as a solvent 1n herbicide formulations 1s probably
1827A 4-5 03/22/84
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TABLE 4-2
U.S. Producers and Estimated Annual Production
Capacities (1983) of Chlorobenzenes*
Chemical/
Manufacturer
Location
Annual Capacity
(Ib. x 106)
Monochlorobenzene:
Dow Chemical Co.
Monsanto Co.
PPG Industries, Inc.
Standard Chlorine Chem.
1,2-D1ch1orobenzene:
Dow Chemical Co.
Monsanto Co.
PPG Industries, Inc.
Standard Chlorine Chem.
1,3-D1ch1orobenzene:
NA
1,4-D1chlorobenzene:
Dow Chemical Co.
Monsanto Co.
PPG Industries, Inc.
Standard Chlorine Chem.
1,2.3-Tr1chlorobenzene:
Standard Chlorine Chem.
Midland, MI
Sauget, IL
Natrium, WV
Delaware City, DE
Total:
Midland, MI
Sauget, IL
Natrium, WV
Delaware CHy, DE
Total:
NA
Midland, MI
Sauget, IL
Natrium, WV
Delaware CHy, DE
Total:
Delaware CHy, DE
170
150
45
150
515
30
6
20
50
106
NA
30
12
30
75
147
NA
1827A
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02/13/84
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TABLE 4-2 (cont.)
Chemical/
Manufacturer
Location
Annual Capacity
(Ib. x 10*)
1.2.4-Tr1ch1orobenzene:
Dow Chemical Co.
Standard Chlorine Chem.
1,3,5-Tr1chlorobenzene:
Southland Corp.
Trlchlorobenzene. Mixed Isomers;
PPG Industries, Inc.
1,2.3.4-Tetrachlorobenzene:
NA
1,2.3,5-Tetrachlorobenzene:
NA
1,2,4,5-Tetrachlorobenzene:
Dow Chemical Co.
Standard Chlorine Chem.
Pentachlorobenzene:
NA
Midland, MI
Delaware City, DE
Great Meadows, NJ
Natrium, WV
NA
NA
Midland, MI
Delaware City, DE
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
*Source: SRI, 1983
NA = Not available
1827A
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02/13/84
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03
—I
3>
TABLE 4-3
A Summary of the Uses of the Chlorinated Benzenes
Chemical
Hajor Uses
Reference
i
05
Monochlorobenzene
,2-D1ch1orobenzene
l,3-D1ch!orobenzene
1,4-D1ch1orobenzene
1,2,3-TMchlorobenzene
1,2,4-Tr1chlorobenzene
Intermediate 1n the manufacture of chloronltrobenzenes, dlphenyl oxide,
DDT and slUcones; as a process solvent for methylene dllsocyanate,
adheslves, polishes, waxes, Pharmaceuticals and natural rubber; as
a degrading solvent.
In the manufacture of 3,4-d1chloroan1l1ne; as a solvent for a wide range
of organic materials and for oxides of non-ferrous metals; as a solvent
carrier 1n production of toluene dllsocyanate; 1n the manufacture of dyes;
as a fumlgant and Insecticide; 1n degreaslng hides and wool; In metal
polishes; 1n Industrial odor control; In cleaners for drains.
As a fumlgant and Insecticide
As a moth repellent, general Insecticide, germicide, space deodorant;
In the manufacture of 2,5-d1chloroan1l1ne and dyes; as an Inter-
mediate; 1n Pharmaceuticals; 1n agricultural fumlgants.
Other than chemical Intermediate usage, the uses of this compound
are the same as 1,2,4-tMchlorobenzene.
As an Intermediate 1n the manufacture of herbicides; as a dye carrier,
as a dielectric fluid; as a solvent; as a heat-transfer medium.
U.S. EPA, 1980
Hawley, 1977
Hawley, 1977
Hawley, 1977
U.S. EPA, 1980
U.S. EPA, 1980
1,3,5-Trlchlorobenzene
1,2,3,4-Tetrachlorobenzene
1,2,3,5-Tetrachlorobenzene
1,2,4,5-Tetrachlorobenzene
Pentachlorobenzene
Hexachlorobenzene
OD
Solvent for high-temperature melting products; as a coolant 1n
electrical Insulators; as a heat-transfer medium, lubricant and
synthetic transformer oil; as a termite preparation and Insecticide;
In dyes.
As a component In dielectric fluids; In the synthesis of fungicide.
NA
As an Intermediate for herbicides and defoliants; as an Insecticide;
moisture-resistant Impregnant; In electric Insulation; 1n packing protection.
In a pesticide used to combat oyster drills; as a chemical Intermediate.
As a fungicide; Industrial waste product 1n the manufacture of perchloro-
ethylene, chlorinated solvents, pesticides and nltroso rubber.
Sllmak et al., 1980
Hawley, 1977
U.S. EPA, 1980
Hawley, 1977
Clement Associates, 1979
Ware and West, 1977
Courtney, 1979
NA = Not available
-------
TABLE 4-4
Estimated Quantities of Chlorobenzenes Lost During Manufacture,
and to the Environment Compared with Total Production In 1983*
(All figures are 1n megagram)
Chlorobenzene
Quantity Lost During
Manufacture
Quantity Lost to
Environment
*Source: 47 FR 26992
NA = Not available
Total Industrial
Production
Mono-
D1-
1,2-
1,3-
1,4-
Tr1-
1,2,3-
1,2,4-
1,3,5-
Tetra-
Penta-
Hexa-
191-303
118-206
0.185-0.608
178-284
0.598-2.111
3.39-10.2
Import
NA
not manufactured
not manufactured
153-259
29.95
NA
166-269
<0.100
0.364-0.924
Import
NA
NA
NA
88,769-128,755
18,301-21,479
147-460
28,310
23.3-74.1
1,253-3,668
111-210
NA
NA
NA
1827A
4-9
02/13/84
-------
released Into the atmosphere. Approximately 0.1% of monochlorobenzene
produced annually was estimated to enter water (Dow, 1978). The U.S. EPA
(Gruber, 1975) estimated that, assuming all of the monochlorobenzene was
produced using a batch process, <0.1% of Us annual production would occur
1n wastewater and <1% would be disposed of on land. For 1,2-d1chloroben-
zene, Dow (1978) estimated that 5-10% of Us annual production would be
released Into air and <0.1% Into water. Using different data, U.S. EPA
(1980) calculated that 2% of the annual production of the l,2-1somer would
be released Into the environment during Its manufacture. For 1,4-d1chloro-
benzene, which 1s used as a space deodorant, Dow (1978) stated that 70-90%
of the yearly production would be released Into air and <5% Into water.
U.S. EPA (1980) estimated that 2% of the total amount of 1,4-d1chlorobenzene
would be released during Us production. Data were not available on poten-
tial environmental releases for other chlorinated benzenes.
Mumma and Lawless (1975) surveyed Industrial processing data and Identi-
fied nine products whose manufacture resulted In the generation of hexa-
chlorobenzene. The authors estimated that 2.4-4.9 million pounds were
generated 1n 1972 and that the manufacture of four products accounted for
>95% of this total. These four products and the estimated quantities of
hexachlorobenzene produced are listed 1n Table 4-5. Hexachlorobenzene 1s
also a constituent of a seed treatment called Grannox NM that 1s Imported
and used In the United States. In 1975, -200,000 pounds of Grannox NM, a
formulation of hexachlorobenzene also containing Maneb, entered the United
States (IARC, 1979). Table 4-4 shows the most recent official figures for
quantities lost from Industrial sources, and quantities released Into the
environment compared with total Industrial production (47 FR 26992).
1827A 4-10 02/13/84
-------
TABLE 4-5
Estimated Quantities of Hexachlorobenzene (HCB)
1n Industrial Wastes and Byproducts 1n 1972*
Product
Perchloroethylene
TMchloroethylene
Carbon tetrachlorlde
Chlorine
Total HCB (103 Ibs)
1750-3500
230-450
200-400
160-390
HCB (Ibs/ton of
4.8-9.5
1.1-2.1
0.4-0.8
product)
0.02-0.04
*Source: Mumma and Lawless, 1975
1827A 4-11 02/13/84
-------
4.3.1. Levels 1n A1r. Investigations of the occurrence of chlorobenzenes
1n air have been conducted 1n Japan and the United States utilizing both
grab and sorbent cartridge techniques. These studies, which have Included
the sampling of polluted air and urban and rural air, have reported the
detection of monochlorobenzene, and various Isomers of d1-, tr1-, tetra- and
hexa-chlorobenzenes. Analysis of Indoor air has Indicated the presence of
monochlorobenzene and the dlchlorobenzenes, and other studies have measured
monochloro- and 1,4-dlchlorobenzene 1n occupational settings.
MorUa and Oh1 (1975) sampled ambient air for the determination of
1,4-d1chlorobenzene levels at six central and suburban Tokyo sites 1n Japan
and found concentrations ranging from 1.5-4.2 vg/m3. Determinations
were also performed on "Indoor" samples from a closet, a bedroom and a
wardrobe; these concentrations were -25-400 times greater than the highest
reported ambient levels.
Pell1zzar1 et al. (1979) presented the results of the analysis of air
samples collected from a number of locations 1n the United States. Samples
from each location were obtained from several sites at a given location and
at numerous times. The samples were analyzed for monochlorobenzene and the
d1- and trlchlorobenzenes. Table 4-6 1s a compilation of these data.
Monochlorobenzene and the dlchlorobenzenes were also measured by
Woj1nsk1 et al. (1979) 1n samples from an Industrially produced cloud that
periodically appears over Henderson, Nevada Industrialized town 10 miles
southeast of Las Vegas. Monochlorobenzene levels were nearly 50 times
greater 1n the Henderson samples (mean: 24325 ng/m3) as compared with the
Las Vegas samples (mean: 458 ng/m3). The mean 1,2-d1chlorobenzene concen-
trations were ~5 times greater over Henderson than over Las Vegas (10291
ng/m3 compared with 3087 ng/m3). However since the methodology was
different, the significance of this finding 1s uncertain.
1827A 4-12 03/22/84
-------
CD
> TABLE
Chlorinated Benzene Levels in Ambient Air
4-6
from Different Locations in the U.S.a
Concentration ranqe, ng/m3
Site
Kin-Buc Disposal
Site, Edison, NJ
^ Baton Rouge, LA
i
co Houston, TX
Niagara Falls, NY
Different NJ Sites0
Date
Sampled MCB
1976/ ND-12,791
1978
1977 ND-900
1977 ND-132
NR ND-119
1978 ND-6072
1,2-DCB
ND-12,433
ND-87
ND-86
ND-444b
ND-5513
1,3-DCB
ND-33,783
ND-102
ND-86
ND-444b
ND-3392
1,4-DCB TCB TeCB PeCB
ND-7000 ND-1327 NR NR
ND ND NR NR
ND ND NR NR
ND-444b ND-4346 ND-451 ND-17
ND ND NR NR
aSource: Taken from Pellizzari et al., 1979
bThese are the values for the unseparated isomers
cThe sites include: Edison, Ground Brook, Paterson, Hoboken, Clifton, Fords, Passaic and Sayreville
ND = Not detected; NR = not reported
MCB = Monochlorobenzene; DCB = dichlorobenzene; TCB = trichlorobenzene; TeCB = tetrachlorobenzene; PeCB =
pentachlorobenzene
CO
CD
-------
In a study of contamination from a hazardous waste site, Barkley et al.
(1980) provided data on chlorobenzene levels from the homes of nine resi-
dents of the "Old Love Canal" area of Niagara Falls, New York. Monochloro-
benzene was detected Inside three of the homes at concentrations ranging
from 60-600 ng/m3. The dlchlorobenzenes (Isomers unseparated) were found
Inside the homes at concentrations ranging from trace levels to 31,000
ng/m3. Samples taken outside the homes over 6-16 hour periods contained
monochlorobenzene, dlchlorobenzenes (Isomers unseparated), tMchlorobenzenes
(Isomers unseparated) and tetrachloro-benzenes (Isomers unseparated) from
nondetectable amounts up to 440 ng/m3, the highest level being found at
one location for the dlchlorobenzene Isomers.
In 1978, the Department of Environmental Protection of New Jersey
Initiated a study of selected volatile organic chemicals 1n ambient air.
Over a 5-month period, a total of 330 samples were obtained at five sites
that Included a mixture of Industrial, residential and semlrural locations.
The results, reported by BozzelH and Kebbekus (1979), Indicated the pres-
ence of 1,2- and 1,4-dlchlorobenzene at all sites. The average concentra-
tions (trace amounts were averaged as the lower detection limit of 0.01 ppb)
were 2096 ng/m3 and 1703 ng/m3 for 1,2- and 1,4-d1chlorobenzene, respec-
tively. Peak concentrations were 46,780 ng/m3 and 93,560 ng/m3, respec-
tively. In a follow-up study, Harkov et al. (1981) sampled air at six sites
1n New Jersey over 24-hour periods every 6 days for a year. Monochloro-
benzene was detected 1n 86% of the samples at an average level of 2.53
yg/m3 and a maximum level of 1.36 v9/ro3>
Field studies were conducted by Singh et al. (1981) 1n California and
Arizona to characterize the atmospheric levels and fate of several organic
chemicals. The samples, collected over 24 hours during a 2-week period at
1827A 4-14 02/13/84
-------
each site, were analyzed for four chlorobenzenes: monochlorobenzene, l,2-d1-
chlorobenzene, 1,3-d1chlorobenzene and 1,2,4-tMchlorobenzene. Table 4-7
presents the results of the analysis.
The atmospheric concentrations of the chlorinated benzenes around
different locations 1n the United States have been measured by a number of
other Investigators. The monitoring sites can be broadly divided Into three
different categories, namely rural/remote sites, urban/suburban sites and
sites near source areas. In a recent report, Brodzlnsky and Singh (1982)
Integrated most of the available U.S. air monitoring data relating to the
levels of chlorobenzenes along with a number of other organlcs Into a
coherent data base. The overall and site-specific mean atmospheric levels
of monochlorobenzene, dlchlorobenzenes, trlchlorobenzenes and tetrachloro-
benzenes compiled 1n this report (Brodzlnsky and Singh, 1982) are shown 1n
Table 4-8.
The levels of pentachlorobenzene and hexachlorobenzene 1n ambient air
samples rarely have been reported. Considering their volatility, the
abundance of these compounds 1n the atmosphere can be speculated to be lower
than the other chlorobenzenes. However, tetrachlorobenzenes, pentachloro-
benzene and hexachlorobenzene have been detected, but not quantified, 1n fly
ashes from municipal Incinerators (Elceman et al., 1979, 1981). High volume
air samples collected from Boston, Massachussetts, and Columbia, South
Carolina, using a glass fiber filter and polyurethane foam trap were
subjected to Interlaboratory analysis of hexachlorobenzene along with other
parameters (Bldleman, 1981). The average concentrations of hexachloroben-
zene 1n Boston (Massachussetts) and Columbia (South Carolina) air were found
to be >0.057 ng/m3 and 0.012 ng/m3, respectively. The percent relative
standard deviations for the two results were determined to be 35 and 43%,
respectively.
1827A 4-15 03/22/84
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TABLE 4-7
Concentrations of Chlorinated Benzenes at Three Sites3
Chemical
Monoch lorobenzene
1
1
1
,2-D1chlorobenzene
,3-D1chlorobenzene
,2,4-TMchlorobenzene
Mean Concentration
Los Angeles, CA
-936
75.1 ± 59.5
46.3 ± 33.7
52.0 ± 36.9
1n nq/m3 ± 1 Standard Deviation15
Phoenix, AZ
-936
135.8 + 209.1
52.3 i 35.5
23.4 i 15.8
Oakland
-468
24.0 i
39.1 +
22.6 i
, CA
30.1
17.4
18.1
aSource: Singh et al., 1981
conversion of ppt unit to ng/m3 1s based on a temperature of 20°C
and a pressure of 1 atmosphere.
1827A
4-16
02/13/84
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TABLE 4-8
Overall and Site-Specific Mean Atmospheric Levels
of Chlorobenzenes throughout the United States*
Mean Concentration, ng/m3
Chemical Total Number Rural-Remote Urban-
of Overall Area Suburban
Localities Areas
Monochlorobenzene
1 ,2-D1chlorobenzene
1 ,3-01chlorobenzene
1 ,4-D1chlorobenzene
Tr1 chlorobenzenes
Tetrachlorobenzenes
56
51
38
24
35
3
3087
1142
571
1563
136
3502
ND
11
40
ND
ND
198
3742
1142
499
1743
128
6196
Areas of
Production
936
1202
902
16
181
853
*Source: Brodzlnsky and Singh, 1983
ND = Not detected
1827A 4-17 03/22/84
-------
In a survey of contamination by hexachlorobenzene around eight Individ-
ual plants, L1 et al. (1976) reported the detection of up to 24 yg/m3
hexachlorobenzene at a distance of 90 feet from one plant. Table 4-9 summa-
rizes the data from this Investigation. Concentrations of hexachlorobenzene
at distances 400-3000 feet downwind from the plants ranged from 0.02-2.7
yg/m3. The authors noted that the highest levels of hexachlorobenzene
contamination were associated with the production of lower chlorinated
hydrocarbons as opposed to the production of chlorine and herbicides, and
that plants with onslte landfill and open pit waste disposal sites had the
highest levels of airborne concentrations of hexachlorobenzene.
Chlorinated benzenes are also present 1n air 1n occupational settings.
Ware and West (1977) reported that the air of facilities manufacturing
1,4-d1chlorobenzene contained an average of 204 mg/m3 dlchlorobenzene
(from 42-288 mg/m3) for certain processes and that no levels <48 mg/m3
were detected throughout the plant. More recently, a survey of monochloro-
benzene exposure was conducted at the chemical companies by the National
Institute for Occupational Safety and Health (NIOSH) (Cohen et al., 1981).
Personal sampling data Indicated that monochlorobenzene levels ranged from
below the detection level to 18.7 mg/m3.
4.3.2. Water. Chlorinated benzenes have been detected 1n ground, surface
and drinking water and 1n Industrial and municipal wastewater. The most
prevalent compound 1s monochlorobenzene. The dlchlorobenzenes, trlchloro-
benzenes, tetrachlorobenzenes, pentachlorobenzene and hexachlorobenzene are
detected Infrequently.
Numerous Investigations have Identified chlorinated benzenes 1n samples
of surface water (Table 4-10). The U.S. EPA STORET system also Includes
monitoring data on the chemicals.
1827A 4-18 03/22/84
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TABLE 4-9
Atmospheric Levels of Hexachlorobenzene Around
Selected Industrial Plants*
Hexachlorobenzene
Concentrations, yg/m3
Company/Location
Vulcan Materials
Wichita, KS
Stauffer Chemical
Louisville, KY
Dow Chemical
Pittsburgh, CA
Du Pont
Corpus Chr1st1, TX
Diamond Shamrock
Deer Park, TX
Ol1n
Mclntosh, AL
C1ba-Ge1gy
St. Gabriel, LA
PPG
Lake Charles, LA
Products
Perchloroethylene, carbon
tetrachlorlde, chlorine
Perchloroethylene, carbon
tetrachlorlde, methylene
chloride, chlorine
Carbon tetrachlorlde, perchlo-
roethylene, chlorine
Carbon tetrachlorlde
Trlchloroethylene, perchloro-
ethylene, chlorine
Pentachloronltrobenzene,
chlorine
Atrazlne, propazlne,
slmazlne
Trlchloroethylene, perchloro-
ethylene, vinyl chloride, vlnyl-
1dene chloride, chlorine, etc.
High Low
24 0.53
7 0.24
0.08 <0.02
ND NO
ND ND
2.2 0.03
0.02 ND
1.7 ND
*Source: L1 et al., 1976
ND = Not detected (<0.02 yg/m3)
1827A
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03/22/84
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00
~J
J>
TABLE 4-10
Chlorinated Benzenes 1n Surface Water
Chemicals
Levels3
Location
Reference
i
INS
o
o
f\J
CD
Trichlorobenzeneb
Monochlorobenzene
1,4-Dichlorobenzene
Monochlorobenzene
Oichlorobenzene
Trichlorobenzene
Tetrachlorobenzene
Pentachlorobenzene
Hexachlorobenzene
Hexachlorobenzene
Monochlorobenzene
Dichlorobenzene0
Trichlorobenzene0
Monochlorobenzene
1,4-D1chlorobenzene
Dichlorobenzene0
Monochlorobenzene
Dichlorobenzene
Trichlorobenzene
Tetrachlorobenzene0
Pentachlorobenzene
Hexachlorobenzene
100-500
*
30-900
ND-17.4 (2.7)
ND-7000
ND-400
ND-1000
ND->10,000
ND->10,000
+ in 7% of all surface
water and in 3% of all
groundwater samples
100-8000
100-200,000
ND-100,000
8000-30,000
Merrimack River, MA Hites, 1973
Glatt River, Germany Giger et al., 1976
River Waters, U.S.
Ohio River
600 sites in NJ
Drainage streams
Niagara Falls, NY
Shackelford and Keith, 1976
Tiber River, Italy Leoni and D'Arca, 1976
Delaware River Sheldon and Hites, 1978
ORVWSC, 1982
Page, 1981
Elder et al., 1981
* T «
-------
OD
ru
TABLE 4-10 (cont.)
Chemicals
Levels3
Location
Reference
D1chlorobenzenec
Tr1chlorobenzenec
Tetrachlorobenzene0
Pentachlorobenzene0
Hexachlorobenzene
D1chlorobenzene°
Trlchlorobenzene0
Tetrachlorobenzene0
Pentachlorobenzene
Hexachlorobenzene
3-71 (27)
0.1-1.6 (0.5)
ND-0.8 (0.12)
ND-0.6 (0.12)
0.02-0.1 (0.05)
ND-77 (11)
ND-8.7 (2.1)
ND-0.2 (0.05)
NO-0.1 (0.05)
0.02-0.1 (0.06)
Great Lakes
Oliver and Nlchol, 1982
Grand River, Canada
Oliver and Nlchol, 1982
aRange (mean) 1n ng/a unless Indicated
''Unidentified Isomers
°A11 Isomers
NO = Not detected; + = detected
CO
oo
-------
Drinking water supplies also have been sampled for chlorobenzene contam-
ination. In a survey of three water treatment plants of the city of New
Orleans, Louisiana, U.S. EPA (1975a) reported finding only one chloroben-
zene, 1,3-d1chlorobenzene, at two of the plants. The reported concentration
was <3 yg/a. The U.S. EPA also found monochlorobenzene and all three
Isomers of dlchlorobenzene at levels <1.0 yg/8. In three of five raw
water supplies that were sampled as part of the National Organlcs Reconnais-
sance Survey (U.S. EPA, 1975b). A follow-up study (U.S. EPA, 1975c) report-
ed concentrations of monochlorobenzene 1n samples of finished drinking water
from the four Initial locations and at five additional sites.
Con1gl1o et al. (1980) reported data on concentrations of volatile
organic chemicals from drinking water treatment plants In the United States.
The frequency of occurrence of 1,2-d1chlorobenzene and 1,2,4-tr1chloroben-
zene 1n finished water originating from surface water was 12.5 and 11.5X,
respectively. Of the facilities using groundwater, 12.9 and 7.1% had drink-
Ing water samples containing 1,4-d1chlorobenzene and monochlorobenzene,
respectively. The other chlorobenzenes were detected 1n <4.5% of the
samples. The authors also reported data from a groundwater survey conducted
1n New Jersey. Of the chlorobenzenes, only the dlchloro- and trlchloroben-
zenes (Isomers unspecified) were detected at concentrations ranging from
<1-100 yg/8. 1n 1 and 3% of the samples, respectively.
Fielding et al. (1981) sampled untreated and finished groundwater, raw
and finished river water and rainwater from 13 unspecified sites throughout
Great Britain. 1,4-D1chlorobenzene was detected at a concentration of 0.08
yg/8. 1n one finished groundwater sample. Page (1981) also surveyed
groundwater and surface water at over 1000 sites throughout New Jersey, 1n a
study designed to compare the relative degree of chemical contamination of
1827A 4-22 03/22/84
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ground and surface water. All Isomers of dlchlorobenzene were found In ~3%
of all the groundwater samples and 4X of the surface water samples.
Analysis of these data and data on 52 other toxic chemicals Indicated that
New Jersey groundwater has a similar pattern and degree of contamination as
surface water. Oliver and Nlchol (1982) sampled drinking water In three
cities on Lake Ontario, both before and after chlorlnatlon. Individual
Isomers of dlchloro- through hexachlorobenzene were found 1n mean concentra-
tions ranging from non-detectable to 13 ng/l. No Increase 1n the level of
concentration was noted 1n these compounds after chlorlnatlon. The levels
of chlorobenzenes 1n the drinking water of three cities bordering Lake
Ontario are given 1n Table 4-11.
As part of a study of the contamination of drinking water by leachate
from a pesticide waste dump site 1n Hardeman County, TN, Clark et al. (1980)
reported data from a U.S. EPA survey of chemicals 1n private wells.
Monochlorobenzene was found 1n 23 of 25 wells at levels from trace amounts
to 41 pg/8. with a median value of 5.0 yg/l. In another study of
possible contamination of drinking water by the disposal of toxic chemicals,
Barkley et al. (1981) found monochlorobenzene and dlchlorobenzenes (Isomers
unspecified) 1n tapwater from all nine of the houses 1n Old Love Canal,
Niagara Falls area. Concentration levels for these two compounds ranged
from 10-60 ng/9, and from 10-800 ng/8., respectively. The tetrachloro-
benzenes and pentachlorobenzene also were found at concentrations up to 2000
and 240 ng/8,, respectively.
The chlorobenzenes have been Identified 1n wastewaters from Industrial
processes and 1n Influents and effluents at municipal sewage treatment
plants. Gaffney (1976) sampled water at four municipal facilities 1n
Georgia that, 1n addition to handling sewage, also treated wastewater from
1827A 4-23 03/22/84
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TABLE 4-11
Chlorobenzene Concentrations 1n Drinking Water from Ontario, Canada3
Chemical
1 ,2-D1chlorobenzene
1 ,3-D1chlorobenzene
1 ,4-D1chlorobenzene
1 , 2,3-Tr1chlorobenzene
1 ,2,4-Tr1chlorobenzene
1 ,3,5-Tr1chlorobenzene
1 ,2,3,4-Tetrachlorobenzene
1 ,2,3,5-Tetrachlorobenzene
1 ,2,4,5-Tetrachlorobenzene
Pen tach lorobenzene
Hexachlorobenzene
Concentration
Range
ND-7
ND-2
8-20
0.1-0.1
1-4
NDb
0.1-0.4
NDb
NDb-0.3
0.03-0.05
0.06-0.2
ng/l
Mean
3
1
13
0.1
2
NDb
0.3
NDb
0.2
0.04
0.1
aSource: Oliver and Nlchol, 1982
bL1m1ts of detection were -0.1 ng/l for the trlchlorobenzenes and -0.05
for the tetrachlorobenzenes.
NO = Not detected
1827A
4-24
02/13/84
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local synthetic carpet mills. Average concentrations reported for dlchloro-
benzenes 1n the Incoming and outgoing water ranged from 3-146 pg/fc and
0-268 ng/a, respectively. For the tMchlorobenzenes, the levels ranged
from 1-60 yg/s, and 0-13 yg/8, for Influent and effluent, respec-
tively. The author concluded that the Increase 1n the dlchlorobenzene
levels was a result of chlorlnatlon performed during the secondary phase of
wastewater treatment.
A U.S. EPA survey of wastewater throughout the United States found that
dlchlorobenzenes and trlchlorobenzenes occurred 1n discharges from Indus-
trial and municipal plants (Ware and West, 1977). The reported concentra-
tions ranged from 15-690 vg/t for l,2-d1chlorobenzene and from 0.25-500
vig/l for 1,2,4-tr1chlorobenzene. Young and Hessan (1978) also reported
the presence of several chlorobenzenes 1n the wastewater of major municipal
facilities 1n southern California. The highest concentrations they found
were for water discharged by the Los Angeles Hyperion Treatment Facility
during December: 1,2-d1chlorobenzene, 435 pg/fc; 1,4-d1chlorobenzene, 230
ng/8,; 1,2,4-trlchlorobenzene, 130 vg/i and 1,3,5-tr1chlorobenzene
<0.2 yg/l. For the other sites, the levels of dlchlorobenzene Isomers
ranged from 0.2-6 vQ/l. None of the facilities used chlorlnatlon to
treat the water.
Neptune (1980) compiled data for organic priority pollutants analyzed 1n
samples taken during several Industrial wastewater surveys conducted from
September 1978 through October 1979. The resulting data were grouped by
their occurrence 1n each of 35 standard Industrial categories. The most
prevalent of the chlorobenzenes was monochlorobenzene, which was present 1n
waste streams from 14 Industrial categories; 1,2-, 1,3- and l,4-d1chloro-
benzene were detected 1n 13, 10 and 14 categories, respectively, with
1827A 4-25 03/22/84
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1,2,4-tr1chlorobenzene present 1n 7 categories. The frequency and range of
concentrations found are summarized 1n Table 4-12.
4.3.3. Food. Investigation of the occurrence of chlorobenzenes 1n food
has been limited primarily to the measurement of hexachlorobenzene. This
concern derived from Its use as a fungicide on the seeds of several food
crops and from Its ability to bloaccumulate 1n the food chain. The bio-
accumulation potential of hexachlorobenzene and the other chlorobenzenes 1s
discussed 1n Section 5.3.
Johnson and Manske (1976) reported the detection of hexachlorobenzene at
levels of 0.0006-0.041 mg/kg 1n food samples from 30 U.S. cities obtained
from the Total Diet Program of the U.S. Food and Drug Administration (FDA).
Based on these and other data, FDA estimated the average dally Intake of
hexachlorobenzene from foods 1n fiscal years 1973 and 1974 to be 0.3978 and
0.0725 yg/day, respectively (IARC, 1979). Leonl and D'Arca (1976), using
analysis data on cooked foods served 1n the Italian Navy, estimated an aver-
age dally Intake of 4.11 ng of hexachlorobenzene. In addition, these
authors surveyed uncooked foods available to the public and found mean hexa-
chlorobenzene levels ranging from none detected to 133.0 ppb (0.133 mg/kg),
with the highest levels occurring 1n butter, lard and pork meat. The aver-
age dally Intake of hexachlorobenzene from uncooked diets was calculated to
be 4.32 vg, a value similar to Intake from cooked diets. Hexachloroben-
zene has also been detected 1n Navy foodstuffs available 1n 3apan (Morlta et
al., 1975a,b; SekHa et al., 1980) and was measured In beef (12 pg/kg),
salmon (9 ug/kg), pork (7pig/kg) and other animal sources of protein
(Morlta et al., 1975a,b). In a survey of over 300 suppliers of cow's milk
1n southern Ontario 1n 1977, hexachlorobenzene residues were Identified 1n
68% of the samples at a level of 0.002 mg/kg 1n fat. The hexachlorobenzene
1827A 4-26 03/22/84
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TABLE 4-12
Frequency and Range of Concentrations of Chlorinated
Benzenes Pollutants 1n Industrial Wastewaters*
Chemical
Monochlorobenzene
1 ,2-D1chlorobenzene
1 ,3-D1chlorobenzene
1 ,4-D1chlorobenzene
1 ,2,4-Tr1chlorobenzene
Total
Samples
31,194
3,268
3,268
3,268
3,266
Samples
Number
of Samples
147
80
44
88
30
Containing >
Range
11-6,400
12-860
10-39
10-410
12-607
10 yg/9.
Mean
Concentration
667
141
21
79
161
*Source: Neptune, 1980
1827A
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02/13/84
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levels found 1n the 1977 survey were significantly below the levels detected
1n a similar survey conducted 1n 1973 (Frank et al., 1979).
Some Information on the presence of other chlorobenzenes 1n food was
also available. MoMta et al. (1975c) reported detecting 1,4-d1chloroben-
zene 1n fish Including mackerel caught 1n Japanese coastal waters. Oliver
and Nlchol (1982) reported detecting all Isomers of dlchlorobenzene, tr1-
chlorobenzene, tetrachlorobenzene, pentachlorobenzene and hexachlorobenzene
1n trout from the Great Lakes. The highest levels were detected for penta-
and hexachlorobenzene and the mean concentrations were 5.5 and 46.8 yg/kg,
respectively. Residues of pentachlorobenzene have also been found 1n oils,
fats and shortening (0.001-0.11 mg/kg) and sugar (-0.002 mg/kg) (U.S. EPA,
1980).
4.3.4. Soil and Sediments. The study of soil contamination by chloro-
benzenes has concentrated on hexachlorobenzene, although more recent surveys
have Included all the chlorobenzenes.
Hexachlorobenzene has been detected 1n sediment samples taken from lakes
throughout Germany (Buchert et al., 1981) and was measured at 0.04 ppm 1n
soil from a farming region 1n Italy where high mortality among birds had
taken place (Leonl and D'Arca, 1976). In 1975, the U.S. EPA examined soil
and aquatic sediments at 26 locations along a 150-mile transect of Louisiana
and found that 46% of the soil samples were contaminated with hexachloroben-
zene at levels of 20-440 ppb. The aquatic sediments contained hexachloro-
benzene at levels of 40-850 ppb (Blackwood and Spies, 1979). In a survey of
nine Industrial plants (see Table 4-9 for site locations) producing chloro-
carbon compounds, L1 et al. (1976) detected hexachlorobenzene 1n soil
samples taken within the plant area at levels >1000 pg/g (1000 ppm) at
three plants. Soil taken from the cornfield adjacent to one plant contained
1827A 4-28 03/22/84
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1.1 v9/9 (1100 ppb) and >3000 pg/g were detected along a boundary road
of another plant.
Elder et al. (1981) sampled sediments In streams draining the Love Canal
area of Niagara Falls, NY, and detected all of the chlorobenzenes (Isomers
unspecified) at levels 1n the ppm range. Oliver and Nlchol (1982) studied
the fate and distribution of chlorobenzenes 1n the Great Lakes and reported
detecting all Isomers 1n the sediments of Lakes Superior, Huron, Erie and
Ontario. The most contaminated lake was Lake Ontario, for which the mean
levels In the sediments of the Individual Isomers ranged from 11-94 ng/g for
the dlchlorobenzenes, from 7-94 ng/g for the trlchlorobenzenes, and from
6-52 ng/g for the tetrachlorobenzenes. The levels of penta- and hexachloro-
benzene were measured as 32 and 97 ng/g, respectively.
4.3.5. Human Tissue Residues. Studies of the transport, fate and bio-
accumulation of the chlorinated benzenes reviewed above Indicate that human
exposure 1s likely from air, food and drinking water (Sections 5.1., 5.2.
and 5.3.). In this section, human ambient exposure 1s confirmed by the
reported levels of chlorobenzene 1n human adipose tissue, blood, breath and
urine; unfortunately, the environmental concentrations were not available
for comparison with the observed tissue concentrations.
Due to the Upophlllc character of the chlorinated benzenes, as Indicat-
ed by their octanol/water partition coefficient discussed 1n Section 5.3.,
adipose and other fatty tissues are the major tissue depots for chlorinated
benzenes. The measured levels of several chlorobenzene Isomers 1n human
adipose tissue are shown 1n Table 4-13.
Human breast milk 1s also high 1n fat content, making this an exposure
route for nursing Infants. Stacy and Thomas (1975) analyzed breast milk
1827A 4-29 02/13/84
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TABLE 4-13
Chlorinated Benzene Residues 1n Human Adipose Tissue
Compound
Country
Tissue
Concentration
(mg/kg)*
Reference
1 ,4-D1chlorobenzene
1.2.4,5-
Tetrachlorobenzene
Hexachlorobenzene
Japan
Japan
Japan
Japan
Japan
United States
Italy
Great Br1t1an
Germany
New Zealand
Canada
Canada
Sweden
2.3
1.88
1.7
0.019
0.21
0.03-0.47
0.491
0.05
6.3
0.31
0.001-0.52
0.01-0.67
0.029-0.071
Morlta and Oh1, 1975
Morlta and Ohl, 1975
Morlta et al., 1975?
Morlta et al., 1975?
Morlta et al., 1975?
Barquet et al. , 1981
Leonl and D'Arca, 1976
Abbott et al., 1972
Acker and Shulte, 1970
Solly and Shanks, 1974
Mes et al., 1979
Mes et al., 1982
Noren, 1983
*Values are for adipose tissue
1827A
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02/13/84
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samples from 20 urban and 20 rural Australian mothers and found the concen-
tration of hexachlorobenzene 1n rural milk (0.079 mg/kg milk) significantly
greater than that 1n urban milk (0.028 mg/kg). A study of another group of
Australian mothers showed the opposite results: rural milk contained 0.042
mg/kg while urban milk contained 0.063 mg/kg (Newton and Greene, 1972). In
France, 18 of 49 breast milk samples contained hexachlorobenzene at con-
centrations of 0.001-0.17 mg/kg whole milk (0.50-3.50 mg/kg on fat basis)
(Goursaud et al., 1972). Relatively low concentrations of pentachloroben-
zene and hexachlorobenzene (0.002 mg/kg and 0.006 mg/kg, respectively) were
found 1n milk samples from Yugoslavian women (Kodr1c-Sm1t et al., 1980). In
another study, 50 milk samples from Helsinki women 1n 1982 (WUkstrom et
al., 1983) contained 0.7-6 vg hexachlorobenzene/kg whole milk (14-240 vg
hexachlorobenzene/kg milk fat). No detectable hexachlorobenzene was found,
however, 1n 57 samples of breast milk from women of rural Arkansas and
Mississippi (Strassman and Kutz, 1977). Levels 1n two Swedish women varied
from 0.029i0.002 mg hexachlorobenzene/kg milk fat 1n one to 0.071+0.005 mg
hexachlorobenzene/kg milk fat 1n the other (Noren, 1983). Courtney (1979)
reviewed some of these and other studies that substantiate the ubiquity of
hexachlorobenzene by the fact that people with no known exposure to the
chlorobenzene had measurable tissue concentrations.
In a study Involving 28,000 people across the United States (Murphy et
al., 1983), hexachlorobenzene was found 1n 4X of 4200 blood serum samples
using a method with a detection limit between 1 and 2 yg/8.. In addi-
tion, hexachlorobenzene was found 1n 93X of 785 adipose tissue samples,
using a method with detection limits around 10-20 v>gA- These findings
were Interpreted as signifying non-occupational exposures. No actual levels
were provided 1n this study.
1827A 4-31 03/22/84
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From the data on chlorobenzene concentrations found 1n human blood and
plasma, H Is apparent that newborns to adults, even those from Industrially
remote areas or those with no known chlorobenzene exposure, experience
exposures to these compounds.
Astolfl et al. (1974) reported hexachlorobenzene at 19 ng/8. 1n the
umbilical cord blood of Infants born 1n Argentina. Ninety-seven rural and
97 urban children from Upper Bavaria all had detectable levels of hexa-
chlorobenzene 1n their blood ranging from 2.8-77.9 ppb (ng/g); the average
concentration was 16.5 ppb (Rlchter and Schmld, 1976). An average concen-
tration of 22 ppb hexachlorobenzene was measured 1n the blood of nonexposed
Australians, whereas occupatlonally exposed people had an average concentra-
tion of 55.5 ppb (range 21-100 ppb) 1n their blood (S1yal1, 1972). MorHa
and Ohl (1975) analyzed the blood of four male and two female residents of
Tokyo for 1,4-d1chlorobenzene and reported an average of 9.5 yg/l.
Wastes containing hexachlorobenzene were spread on a landfill 1n western
Louisiana as a fly control measure (Burns and Miller, 1975). Blood levels
of hexachlorobenzene In 22 husband-wife pairs living near the landfill were
analyzed. The average blood level for the men was 5.10 ppb, which was
significantly higher than that for the women, which was 1.70 ppb. Forty-six
Louisiana residents not living 1n the Immediate vicinity of the landfill had
average blood levels of 0.5 ppb hexachlorobenzene, while chemical plant
workers 1n the area had a blood concentration range of 14-233 ppb. The
levels of chlorinated benzenes 1n the blood of nine residents of the Love
Canal area 1n Niagara Falls, New York, were measured and are shown 1n Table
4-14 (Barkley et al., 1980).
Although the chlorobenzenes bloaccumulate 1n human adipose tissue and
are detected In human blood, the levels are tempered by the elimination pro-
cesses. The expired breath and urine of nine residents of the Love Canal
1827A 4-32 02/13/84
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TABLE 4-14
Chlorinated Benzenes 1n the Blood of Nine Residents
of Love Canal 1n Niagara Falls, New York*
Compound
Monochlorobenzene
D1-1somers
Tetra-lsomers
No. of Positive
Results
8
9
1
Blood
Concentration
(ng/mi)
0.05-17.0
0.15-68
2.6
*Source: Barkley et al., 1980
1827A
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area contained measurable levels of the chlorobenzenes as shown In Table
4-15 (Barkley et al., 1980).
The concentrations of chlorinated benzenes reported for human tissue
(see Table 4-13) and blood, breath and urine (see Tables 4-14 and 4-15)
Indicate that humans absorb chlorinated benzenes. The bloaccumulatlon of
the chlorinated benzenes 1s offset by metabolism and elimination from the
body.
4.4. RELATIVE SOURCE CONTRIBUTIONS TO TOTAL EXPOSURE
The monitoring studies discussed 1n the preceding section Indicate that
chlorinated benzenes are present 1n the environment and that human exposure
to one or more of these substances 1s likely to result from the Inhalation
of air or the 1ngest1on of water or food. The Intent of this section 1s to
estimate the relative degree that these three media — air, water and food
-- contribute to a person's overall exposure. There are several limitations
to this approach. First, no comprehensive study of human exposure to the
chlorobenzenes has been conducted; the available monitoring data Indicate
the presence of the substances under the conditions of a given study and do
not establish universal levels of exposure. Consequently, the studies that
are used 1n this section were selected on the basis of being the most likely
to represent general population exposure. Data on Instances of gross
contamination; I.e., local pollution from landfill or in an occupational
setting, were not used. Second, no single study has analyzed any one medium
for all of the chlorobenzenes. Hence, only data from a single study were
used 1n the calculations for one type of exposure; aggregate or combined
data were not used. Third, all monitoring studies are limited either on
terms of sampling duration or the number of locations sampled; studies with
the widest geographical sampling locations and longest duration of sampling
1827A 4-34 03/22/84
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TABLE 4-15
Chlorinated Benzenes 1n the Breath and Urine of Nine
Residents of Love Canal In Niagara Falls, New York*
Compound
Monochlorobenzene
D1-1somers
Tr1-1somers
Tetra-1somers
Pentachlorobenzene
No. of Pos1
Breath
1
7
2
2
1
tlve Results
Urine
6
7
0
0
0
Concentration
Breath
(ng/m3)
T
T-5000
T-90
30-180
70
Range
Urine
(ng/i)
20-120
40-39,000
NO
NO
ND
*Source: Barkley et al., 1980
T = Trace; ND = not detected
1827A
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were favored for use 1n the calculations. Finally, quantitative data on the
absorption of the various chlorobenzenes by humans through the lungs, skin
or gastrointestinal tract 1s not available. For this reason, the data 1n
this section are estimates of yearly average ambient exposure levels (I.e.,
the amount potentially Inhaled or Ingested) and are not physiological
exposure levels.
4.4.1. A1r. The monitoring data used for the estimation of Inhalation
exposure (Table 4-16) are taken from the overall mean concentration values
given 1n Table 4-7. In addition, this table presents estimates of the total
yearly exposure of an adult man, adult woman, child and Infant using stan-
dard respiratory volumes of 8.4x10*, 7.7x10*. 5.5x10* and 1.4x10*
I/year, respectively (ICRP, 1975). The Inhalation exposure estimate will
be different for rural/remote, urban/suburban and source areas.
4.4.2. WaUr. The estimation of exposure of chlorobenzenes from drinking
water requires that the mean or median concentrations of these compounds 1n
finished water originating from a large number of both U.S. surface and
groundwater be known. As discussed 1n Section 4.3.2., only a limited number
of monitoring data for the levels of chlorobenzenes 1n finished water
samples are available. Therefore, an assessment of the exposure of chloro-
benzenes through the Ingestlon of drinking water cannot be made at the
present time. However, the maximum concentrations of the chlorobenzenes
found 1n U.S. drinking water are the following: monochlorobenzene, 5.6
jjg/l; 1,3-d1chlorobenzene, <3 ug/l; and trlchlorobenzene (Isomer
unspecified), 1.0 pg/l (NAS, 1977). If the maximum fluid Intake by an
Individual 1s assumed to be 711.8 I/year (ICRP, 1975), the maximum
exposure of an Individual chlorobenzene Isomer through Ingestlon of finished
water can be estimated to be <4 mg/year.
1827A 4-36 03/22/84
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TABLE 4-16
Estimated Yearly Exposure to Several
Chlorinated Benzenes Via Inhalation
Exposure (mg/yr)
Chemical
Monochlorobenzenes
1 ,2-D1chlorobenzene
1 ,3-D1chlorobenzene
1 ,4-D1chlorobenzene
Trlchlorobenzenes
Tetrachlorobenzenes
Mean Ambient Con-
centration (ng/m3)*
3087
1142
571
1563
136
3502
Adult
Man
25.9
9.6
4.8
13.1
1.1
29.4
Adult
Woman
23.8
8.8
4.4
12.0
1.0
27.0
Child
(10 yr)
17.0
6.3
3.1
8.6
0.7
19.3
Infant
(1 yr)
4.3
1.6
0.8
2.2
0.2
4.9
*Mean levels obtained from Table 4-8
1827A
4-37
03/29/84
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4.4.3. Food. Hexachlorobenzene 1s the only chlorinated benzene whose
presence 1n food has been systematically Investigated. Based on data from
the Total Diet Program, the FDA estimated the average dally Intake of
hexachlorobenzene for fiscal year 1974 to be 0.0725 yg/day (IARC, 1979).
This would result 1n a yearly exposure of 0.03 mg hexachlorobenzene from
food sources.
4.5. SUMMARY
Annual production of chlorinated benzenes 1n 1983 1s on the order of 450
million pounds, the majority of which 1s accounted for by monochlorobenzene
and dlchlorobenzenes. Production of the tr1- and tetrachlorobenzenes and
pentachlorobenzene 1s on the order of millions of pounds/year. Hexachloro-
benzene 1s not currently produced as a commercial product 1n the United
States (IARC, 1979), although 1t 1s a constituent of several Imported
products and 1s a byproduct or waste material 1n the production of many
chemicals (Humma and Lawless, 1975). These compounds are used 1n a number
of organic chemical syntheses, Including the synthesis of other chloroben-
zenes, and have applications as solvents, electrical equipment Insulators,
pesticides, herbicides and fungicides. Emissions of chlorobenzenes are most
likely to occur during their manufacture or use as Intermediates and from
the disposal of waste products from manufacturing operations. Hexachloro-
benzene, for example, which 1s Imported but not produced commercially 1n the
United States, occurs as a byproduct 1n the synthesis of nine other chloro-
carbons; 2-5 million pounds may be generated each year.
Chlorinated benzenes have been Identified 1n air, food and soil, and 1n
surface, ground and drinking water. The highest concentrations have been
found near manufacturing and waste disposal sites, although no study has
attempted to characterize the contribution of any one source to the total
1827A 4-38 03/22/84
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environmental contamination by chlorobenzenes. Ambient air and maximum
water levels are 1n the yg/m3 and mg/t range, respectively, although
monitoring studies for finished water have been limited. The most frequent-
ly detected compounds 1n air and water were monochlorobenzene and the d1-
and trlchlorobenzenes. Penta- and hexachlorobenzene are more frequently
found 1n food and soil, although their detection may reflect more of the
concern over their use as pesticides and fungicides, or their presence as
contaminants 1n pesticides or fungicides, rather than the absence of the
other chlorobenzenes.
No comprehensive study of human exposure to the chlorobenzenes has been
conducted, although their ubiquity 1n the environment and the detection of
measurable residues 1n human tissue (see Section 5.3., B1oaccumulat1on/B1o-
concentratlon) Indicate that human exposure and absorption occur. The
contribution of the chlorobenzenes from all the three media (air, water and
food) to a person's total exposure cannot be made with the limited environ-
mental monitoring data. The available data, however, Indicate that human
Inhalation exposure to chlorobenzenes may be higher than 1ngest1on exposure
either through drinking water or through foods.
1827A 4-39 03/22/84
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5. ENVIRONMENTAL TRANSPORT AND FATE
The following sections consider the transport and fate of the chlori-
nated benzenes through the three environmental media (air, water and soil)
and their potential to accumulate or concentrate 1n plant, animal, and
ultimately, human tissues. Transport between the various environmental
media 1s governed by the physical and chemical characteristics of the com-
pounds and their Interaction with components of the environment. Evapora-
tion rates and solubilities Influence transport from water and soil Into
air. Leaching rates, adsorption, rainfall, soil type and desorptlon affect
the movement of chlorobenzenes from soil and sediment Into water and ground-
water, as well as from water Into sediment and soil. The fate of chloroben-
zenes 1n the environment depends on degradatlve processes, either abiotic
degradation by chemical reactions or photolysis, or blotlc degradation by
microbes, and on the rate at which these compounds are stored or accumulated
by plants, animals and humans.
5.1. TRANSPORT
5.1.1. A1r. The transport and distribution of the chlorobenzenes 1n the
atmosphere has not been Investigated. One study has suggested that distri-
bution of one of the chlorobenzenes 1n air may be global. Atlas and G1am
(1981) reported detecting hexachlorobenzene at a mean level of 0.10 ng/m3
1n air samples taken at a remote North Pacific Ocean atoll where the only
source could be air transport. These data led the authors to suggest that
hexachlorobenzene 1s well mixed 1n the atmosphere and has wide distribution
1n the Northern Hemisphere. A study of environmental contamination by hexa-
chlorobenzene from Industrial plants (L1 et al., 1976) provided some data
that Indicated such emissions can be spread by wind from point sources. The
1828A 5-1 03/22/84
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authors reported that the emissions, which were 1n both vapor and partlcu-
late form, were detected at levels from 0.1-29.0 pg/m3 near the produc-
tion facilities and decreased to 0.10-0.50 as much 200 feet or more down-
wind. The tendency of the hexachlorobenzene to remain 1n the atmosphere was
not studied.
Entry Into the atmosphere from other media 1s determined mainly by a
substance's molecular weight, water solubility and vapor pressure. Chloro-
benzenes have vapor pressures ranging from 0.05-11.8 mmHg at 20°C (see
Section 3.3.). In general, these vapor pressures decrease with the Increase
1n the number of chlorine substltuents. Chlorobenzenes are likely to enter
the atmosphere as a result of evaporation from soil and water and these
types of studies are discussed 1n the following sections.
5.1.2. Water. Chlorobenzenes have low solubility 1n water, with the solu-
bility decreasing as the number of chlorine substltuents Increases, although
some variation 1s evident among the Isomers (Hawley, 1977; Sax, 1979; Weast,
1979) (see Section 3.3.). Once dissolved 1n water, despite their relatively
low vapor pressures and high molecular weights, the chlorinated benzenes
tend to evaporate quickly (Mackay and Wolkoff, 1973). Two laboratory
studies Indicate that evaporation of some of the Chlorobenzenes from an
aqueous solution will be as rapid as a few minutes to a few days.
Garrison and Hill (1972) found that >99% of mono-, 1,2- and l,4-d1- and
1,2,4-tr1chlorobenzene had evaporated within 4 hours from aerated distilled
water solutions and within 72 hours from nonaerated solutions. Mono-, 1,2-
d1- and 1,4-d1chlorobenzene volatilized completely 1n <1 day from aerated
solutions containing mixed cultures of aerobic microorganisms. l,2,4-Tr1-
chlorobenzene also evaporated, but less rapidly, with 2% of the Initial
concentration remaining after 80 hours. Lu and Metcalf (1975) provided
1828A 5-2 03/22/84
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evidence of monochlorobenzene's volatility from water through their study of
this chemical's b1odegradab1!1ty 1n a model ecosystem. They noted that
after 48 hours, 96% of the radloactlvely labeled compound added to the model
system was found 1n the traps that sampled the system's atmosphere.
A 1-year field study of the transport of 1,4-d1chlorobenzene 1n Lake
Zurich, Switzerland, also Indicated an Important role for evaporation 1n the
removal of chlorobenzenes from water (Schwarzenbach et al., 1979). The
authors found that the main Input of 1,4-d1chlorobenzene Into the lake was
from wastewater treatment plants and that the half-life of the chemical was
-100 days. From a comparison of the seasonal variation 1n evaporation
rates, they concluded that transport Into the atmosphere 1s the predominant
Influence on the loss of 1,4-d1chlorobenzene from the lake. Their data
Indicated that of the 90 kg/year entering the lake, 60 kg was lost to the
air, 2 kg entered lake sediments and 28 kg was 1n the lake's outflow.
In addition to laboratory and field Investigations, theoretical studies
of the transport of chlorobenzenes 1n aquatic systems may be useful 1n
predicting the distribution of these compounds and their removal from water
by evaporation and sedimentation. Using Henry's Law Constant and various
assumptions of water depth, air speed, etc., the half-life of evaporation
from water can be calculated. For chlorobenzene, 1,2-d1chlorobenzene and
1,2,4-tr1chlorobenzene, these values are 4.6 minutes, 8.1 minutes and 0.75
hours, respectively. Falco et al. (1982) developed a mathematical model for
assessing the transport and degradation of materials released from land-
fills and waste storage lagoons. The parameters Incorporated Into the model
Included coefficients for the following: (1) octanol/water partition, (2)
hydrolysis rate, (3) photolysis rate, (4) bacterial degradation rate, (5)
oxidation rate, (6) overall degradation rate and (7) volatilization rate.
The predictions made using the model are therefore limited by the available
1828A 5-3 03/29/84
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data base and rate coefficients. In their modeling, Falco et al. (1982)
used the model to predict the transport and persistence of chlorobenzenes
for the following types of surface waters: (1) a river capable of trans-
porting a chemical 50-100 miles 1n 5 days, (2) a pond with an average
retention time of 100 days and (3) a lake or reservoir with a retention time
of 1 year. For comparative purposes, a summary of the authors' results for
the lake or reservoir 1s presented 1n Table 5-1.
5.1.3. Soil. Chlorobenzenes have an Intermediate to high potential for
adsorption onto soils, which tends to Increase with Increasing number of
chlorine substltuents. Once adsorbed, their movement within the soil 1s
dependent on the soil type and the nature of the solvent or leachate. In
the absence of a solvent, transport Into adjacent soil and the atmosphere 1s
likely to result from vapor phase diffusion.
Wilson et al. (1981) studied the transport, over a 21-day period, of a
mixture of monochlorobenzene, 1,4-d1chlorobenzene, 1,2,4-tr1chlorobenzene
and 10 other organic chemicals through a column of sandy soil having a low
organic matter content. Using water as a solvent, these Investigators noted
that for the chlorobenzenes the retardation factors (velocity of the sol-
vent/velocity of a compound) Increased with the chlorine number regardless
of the Initial concentration of the compounds. These authors also reported
that up to 50% of the applied monochlorobenzene evaporated and -50% of the
amount of all three chlorobenzenes was degraded or unaccounted for (Table
5-2). These results Indicated that chlorinated benzenes are likely to leach
Into groundwater and this mobility 1n groundwater was confirmed 1n a field
study by Roberts et al. (1980).
Studies on the transport of hexachlorobenzene Indicate a high potential
for soil adsorption and for volatilization from porous soils. Ausmus et al.
1828A 5-4 03/29/84
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TABLE 5-1
Predicted Transport and Fate of Chlorinated Benzenes
Released from Landfills and Lagoons3
Property
Movement from point of
entry to outlet
Potential for degradation
or elimination
Amount absorbed onto
suspended sediments
Amount taken up by fish
Estimated volatilization
to atmosphere
Total
Mono-
5-9
83-94
-------
TABLE 5-2
Transport of Chlorinated Benzenes 1n Sandy Soil*
Chemical
Monochlorobenzene
1
1
,4-D1chlorobenzene
, 2, 4-Tr1 chlorobenzene
Percentage
Volatilized
27-54
ND
ND
of Total Chlorobenzene
Degraded or
Not Accounted For
20-40
51-63
54-61
Applied
Column
Effluent
26-33
37-49
39-46
*Source: Wilson et al., 1981
ND = Not determined
1828A 5-6 02/13/84
-------
(1979) applied C14-labeled hexachlorobenzene to soil cores taken from a
pine forest and monitored Us evaporation and leaching by water over 21
days. Of the amount applied, <1% was lost by volatilization or 1n the
leachate, and none was degraded as Indicated by the absence of labeled
CO . Farmer et al. (1980a) examined the vapor phase diffusion of hexa-
chlorobenzene through a high clay, low organic material soil (39 and 1%,
respectively) and reported diffusion to be Increased by the soil porosity
and decreased by the soil's water content. The same authors (Farmer et al.,
1980b) also found that highly compacted wet soil covers were most effective
1n reducing hexachlorobenzene volatilization after dumping Into a land-fill.
A water cover 1n a temporary storage lagoon was also effective. Each 10°C
rise 1n soil temperature Increased volatilization fluxes 3.5-fold. Griffin
dnd Chou (1981) Investigated the adsorption and mobility of polychlorlnated
and polybromlnated blphenyls and hexachlorobenzene 1n seven different soil
types with Increasing amounts of organic carbon. The adsorption of hexa-
chlorobenzene Increased with Increasing amounts of organic carbon. Further,
they noted that hexachlorobenzene was Immobile and was not leached from the
three soils that were tested with water and a leachate from a landfill.
K values for chlorinated benzenes are: chlorobenzene (537), l,2-d1-
oc
chlorobenzene (977), 1,4-d1chlorobenzene (1259), 1,2,3-tr1chlorobenzene
(2630), 1,2,4-tMchlorobenzene (2042) and hexachlorobenzene (38,000)
(CalamaM et al., 1983).
5.2. FATE
5.2.1. A1r. The degradation of chlorobenzenes 1n air has been studied 1n
a fair amount of detail. In theory, chlorobenzenes dispersed 1n air may be
degraded by chemical- or sunlight-catalyzed reactions or may be adsorbed
onto particles that settle or are removed from the atmosphere by rain. A
measure of the effectiveness of these factors 1s the atmospheric residence
1828A 5-7 03/22/84
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time. One study has made estimates of residence times for various chloro-
benzenes. Singh et al. (1981) conducted field studies 1n California and
Arizona and analyzed air samples over 2-week periods for 33 organic chemi-
cals Including monochlorobenzene, the dlchlorobenzenes and an unspecified
Isomer of trIchlorobenzene. The estimated residence times of these chemi-
cals and dally percentage of each lost from the atmosphere are presented In
Table 5-3.
5.2.2. Water. The fate of chlorobenzenes 1n aquatic systems has not been
completely characterized, although Initial studies Indicate that degradation
of chlorobenzenes Is possible by mlcroblal communities 1n wastewater treat-
ment plants and 1n natural bodies of water. Other Investigations have Indi-
cated that chlorobenzenes have a high potential for bloaccumulatlon and bio-
concentration by aquatic species (Section 5.3.). Removal of chlorobenzenes
by adsorption onto suspended material that 1n turn settles and Is Incorpo-
rated Into sediments has not been demonstrated.
Lee and Ryan (1979) examined the degradation of various chlorinated com-
pounds by microbes 1n samples of water and sediments taken from a river 1n
Georgia. They observed that the degradation rates fit first-order expres-
sions, although the degradation of the chlorinated compounds 1n water was
slow. In the sediment samples, monochlorobenzene was found to have a
half-life of 75 days, which was longer than the chlorinated phenols, but
more rapid than the degradation of hexachlorophene and DDE. In contrast,
hexachlorobenzene showed no degradation by water or sediment microbes.
Davis et al. (1981) conducted a similar experiment using samples of mlc-
roblal populations from Industrial and municipal wastewater treatment plants
and 1,2-d1chlorobenzene along with other compounds. The dlchlorobenzene at
a concentration of 50 ng/8. was degraded by both systems within 7 days.
1828A 5-8 02/13/84
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TABLE 5-3
Estimated Atmospheric Residence Time and Dally Loss
Rates for Several Chlorinated Benzenes3
Chemical
Monochlorobenzene
1 ,2-D1chlorobenzene
1 ,3-D1chlorobenzene
1 ,4-D1chlorobenzene
Trlchlorobenzene^
Residence Times
(days)b
13
38.6
38.6
38.6
116.0
Dally Loss Rate
(percent)0
7.4
2.6
2.6
2.6
0.9
aSource: Singh et al., 1981
bCalculated assuming an average dally (24-hour) abundance of OH radicals
of 106 molecules/cm3
cFor 12 hours of sunlight
dlsomer unspecified
1828A 5-9 02/13/84
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This rate, which was more rapid than the rate for phenol but slower than
that measured for benzene, was described as "comparatively rapid."
Using a model aquatic ecosystem, Lu and Metcalf (1975) Investigated the
blodegradatlon and b1oaccumulat1on of various chemicals Including monochlo-
robenzene and hexachlorobenzene. Both compounds were found to have high
"ecological magnification" Indices and accumulated 1n both aquatic plants
and animals. Both chemicals had low b1odegradab1!1ty Indices and were, 1n
general, metabolized to monochloro- and pentachlorophenol, respectively.
A number of other Investigators have studied the b1odegradab1lHy of
chlorinated benzenes and these results are summarized 1n Table 5-4. In
general, these results suggest that the b1odegradabH1ty decreases as the
number of chlorine substltuents Increases. In addition to these laboratory
studies, Zoeteman et al. (1980) Indicated that chlorobenzene, o-d1chloroben-
zene, £-d1chlorobenzene, 1,2,4-tr1chlorobenzene and hexachlorobenzene
degrade 1n river water with half-lives of 0.30, 3-2, 1.1-25, 1.8-28 and 0.5
days, respectively, as Indicated by monitoring at various stations along the
Rhine River. These half-lives are likely to be very Inaccurate since only a
limited number of samples were taken.
Roberts et al. (1980) studied the transport and degradation of monochlo-
robenzene, o-, m-, j>-chlorobenzenes and 1,2,4-tr1chlorobenzene 1n ground-
water after Injection by analyzing monitoring wells at different distances
from the Injection well. No degradation was noted.
5.2.3. Soil. Studies on the fate of dlchlorobenzenes, trichlorobenzenes,
pentachlorobenzene and hexachlorobenzene 1n soil have Indicated that the
chlorobenzenes are usually resistant to mlcroblal degradation (however,
compare Ballschmlter and Scholz, 1980) and that chlorophenols are likely
degradation products. Beck and Hansen (1974) studied the blodegradatlon of
1828A 5-10 03/22/84
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CD
IVJ
CD
TABLE 5-4
Aqueous B1odegradab111 ty Studies of Chlorinated Benzenes
Method
Warburg
Mineral salts
shake flask
MITI BOO Test
Warburg (phenol
acclimated
cultures)
BOO 5-day
Natural water
Warburg (sewage)
Results (X Degradation)
MCB o-OCB £-OCB 1.2.4-TCB HCB
3.9 BOOT Trace of 3.4 BOOT No degradation
degradation
100* 18-66* 0-61* 0-70* 0-56*
Resistant to Resistant to Resistant to
degradation degradation degradation
16.1 BOOT 2.4 BOOT
1.5 BOOT
Degradation fast slow degradation
1n fresh water,
slower tn estuar-
1ne and marine
water
0-54
Reference
Nalaney and NcKlnney, 1966
Tabak et al., 1981
Kawasaki, 1980
Chambers et al., 1963
Heukeleklah and Rand, 1965
Pfaender and Bartholomew,
1982
Gaffney, 1976
*Percent degradation after acclimation (subculture every 7 days)
CO
X*
CD
-------
Qulntozene, a fungicide, and two of Us Impurities, penta- and hexachloro-
benzene. Soil samples treated under laboratory conditions with penta- and
hexachlorobenzene at rates equal to 10 mg/ha were monitored over a period of
600 days. From the slopes of the degradation curves, the authors estimated
the half-lives of penta- and hexachlorobenzene to be 194-345 and 969-2089
days, respectively. Beall (1976) applied hexachlorobenzene at an amount
equivalent to 750 g/ha to sections of turf In a greenhouse. Within 2 weeks,
55% of the hexachlorobenzene had disappeared from the top 2 cm of soil, most
likely a result of evaporation. Very little of the chemical disappeared
from the 2-4 cm-deep soil layer over the next 19 months. Isensee et al.
(1976) also found hexachlorobenzene to be highly persistent 1n soil. Hexa-
chlorobenzene was applied to samples of sterile and nonsterlle soil to
create levels of 0.1, 1, 10 and 100 ppm. After storage of the samples under
aerobic (sterile and nonsterlle) and anaerobic {nonsterlle) conditions for 1
year, analysis Indicated that none of the hexachlorobenzene had degraded 1n
any sample.
Studies with the d1~ and trlchlorobenzenes have Indicated that these
compounds are also persistent, but not to the degree reported for hexachlo-
robenzene. Ballschmlter and Scholz (1980) Investigated the metabolism of
1,2-, 1,3- and 1,4-d1chlorobenzene by a soil microbe of the Pseudomonas
genera. In culture, the soil microbe was capable of degrading the compounds
to dlchlorophenols and dichloropyrocatechols. Similar cultures of Pseudo-
monas also metabolized the tr1- and tetrachlorobenzenes to their respective
chlorophenols. In an experiment that more closely duplicated conditions 1n
nature, Marlnucd and Bartha (1979) treated fresh field soil with radio-
labeled 1,2,3- and 1,2,4-tr1chlorobenzene. They found very slow rates of
degradation for these compounds, 0.35 and 1.00 nmol/day/20 g of soil,
1828A 5-12 02/13/84
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respectively. These authors also noted that the amount of organic material
1n the soil had no effect on the rate, but 1t did appear to reduce evapora-
tion of the chlorobenzenes. The primary degradation products were chloro-
phenols. Haider et al. (1974), using 14C-labeled compounds 1n soil, found
18.3, 1.1 and 1.1% CO after 1 week of Incubation of monochlorobenzene,
o-d1chlorobenzene and £-chlorobenzene, respectively.
5.3. BIOCONCENTRATION, BIOACCUMULATION, AND BIOMAGNIFICATION
The occurrence of toxic substances 1n the environment raises the Issues
of whether humans may be exposed to them via air, water or food and, 1f so,
what are the physiological exposures. The transport and fate of the chloro-
benzenes (see Sections 5.1. and 5.2.) are primary determinants of human
exposure to the environmental sources of these compounds, but the more
crucial physiological exposure levels are determined by the ease with which
a compound crosses biological membranes. B1oaccumulat1on, alternately
expressed as biological persistence, 1s the net result of the absorption and
the elimination rate of a compound and, therefore, determines the level and
duration of human physiological exposure.
The terminology used In this section will follow the suggestion of Macek
et al. (1979): bloconcentratlon Implies that tissue residues result only
from exposure to the ambient environment (I.e., air for terrestrial or water
for aquatic species); bloaccumulatlon considers all exposures (air, water
and food) of an Individual organism as the source of tissue residues; and
blomagnif1cat1on defines the Increase 1n tissue residues observed at suc-
cessively higher trophic levels of a food web.
Tissue concentrations of the various chlorinated benzenes 1n laboratory
and field populations are discussed 1n Chapter 6, Ecological Effects. It 1s
sufficient to state here that the chlorinated benzene Isomers do reach mea-
1828A 5-13 03/22/84
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surable tissue levels 1n exposed organisms. The factors controlling their
accumulation, however, are pertinent for discussion 1n this section.
Studies of the accumulation of xenoblotlcs from environmental sources
Into living cells and tissues have been conducted mainly with aquatic
species and food chains. Under the general experimental design, the organ-
Isms are exposed to sublethal concentrations of the test material under
static or flowing water conditions. After exposure, the concentration of
the test material 1n the organism 1s quantified and a bloconcentratlon
factor (BCF) 1s calculated as the ratio of the concentration 1n tissue (or
the whole organism) to the concentration 1n the water or food; air concen-
tration 1s substituted Into the denominator for calculating the BCF for
terrestrial organisms (Macek et al., 1979; Velth et al., 1980).
From such studies, 1t appears that concentration 1s determined by water
solubility, the octanol/water partition coefficient (Lu and Metcalf, 1975)
or the number of chlorine atoms on the molecule (Barrows et al., 1980). All
three parameters correlate well with the BCF (Kenaga and Goring, 1980;
Metcalf, 1977; Lu and Metcalf, 1975). Table 5-5 shows the direct relation-
ships between Increasing chlorlnatlon, Increasing I1p1d . solubility as
Indicated by the octanol/water partition coefficient and the Increase 1n the
BCF for chlorinated benzenes 1n fish. For example for salmon (Oliver and
N1mm1, 1983) all the chlorobenzenes except hexachlorobenzene obeyed:
log BCF = -0.632 * (1.022 + 0.057) log K at the high exposure end,
and
log BCF = -0.869 + (0.997 * 0.056) log K at the low exposure end.
Accordingly, the octanol/water partition coefficient 1s a good first
approximation of the BCF 1n aquatic organisms (r = 0.948, n = 8 In flowing
water) (Kenaga and Goring, 1980).
1828A 5-14 02/13/84
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TABLE 5-5
00
!\J
CO
Octanol/Hater Partition Coefficients, B1oconcentrat1on Factors
and Biological Half-lives for Chlorinated Benzenes 1n F1sh
I
LTI
Compound
Monochlorobenzene
1
1
1
1
1
1
1
,2-01 ch lorobenzene
,3-D1chlorobenzene
,4-D1ch lorobenzene
,2,4-Tr1chlorobenzene
*
,3,5-TMchlorobenzene
,2,3-Tr1chlorobenzene
,2,3,5-Tetrachlorobenzene
Octanol/Water
Partition
Coefficient3
690
NR
NR
2,511
2,510
2,754
2,750
2,400
2,344
2,400
2,340
NR
NR
2,400
3,388
NR
17,000
17,000
NR
17,000
10,500
15,000
14,100
15.850
12,900
15,850
28,800
87,100
Species
NS
fathead minnow
rainbow trout
blueglll
rainbow trout
blueglll
rainbow trout
blueglll
blueglll
rainbow trout
rainbow trout
rainbow trout
rainbow trout
trout
guppy
fathead minnow
fathead minnow
green sunflsh
blueglll
rainbow trout
rainbow trout
NS
rainbow trout
guppy
rainbow trout
guppy
blueglll
guppy
BCFb
12
450
46
89
270-560
66
420-740
15
60
214
370-720
32-107
80
231
100
1700
2100
2300
182
890
1300-3200
491
1800-4100
760
1200-2600
700
1800
3900
Biological
Half-I1fec
(days)
NR
NR
NR
<1
NR
<1
NR
<7
<1
NR
NR
<1
NR
NR
0.7
<7
NR
NR
>1<3
NR
NR
NR
NR
1.7
NR
1.5
>2<4
2.5
Reference
Kenaga and Goring, 1980d
VeHh et al., 1979
Branson, 1978
VeHh et al.. 1980
Oliver and N11m1. 1983
VeHh et al.. 1980
Oliver and Nllml. 1983
U.S. EPA. 1980
VeHh et al.. 1980
Neely et al.. 1974
Oliver and N11m1, 1983
Galassl et al.. 1982
CalamaM et al., 1982
U.S. EPA. 1980
Konemann and Van Leeuwen.
1980
Koslan et al.. 1981
VeHh et al.. 1979
VeHh et al., 1979
Barrows et al.. 1980
VeHh et al.. 1979
Oliver and N11m1, 1983
Kenaga and Goring, 1980
Oliver and N11m1, 1983
Konemann and Van Leeuwen,
1980
Oliver and N11m1, 1983
Konemann and Van Leeuwen.
1980
VeHh et al., 1980
Konemann and Van Leeuwen,
1980
CD
-------
CD
TNJ
CD
Octanol/Water
Compound Partition
Coefficient3
1 ,2, 4, 5-Tetrach lorobenzene 33,100
47,000e
NR
1 , 2, 3, 4-Tetrach lorobenzene 28,800e
NR
Pentachlorobenzene 87,096
C
87,100f
154,000
490,000
LTI Hexachlorobenzene NR
L 170,000
& 170,000
170,000
169,824
316,0009
168,000
NR
NR
TABLE 5-5 (cont.
Species
rainbow trout
NS
carp
rainbow trout
carp
blueglll
rainbow trout
NS
guppy
fathead minnow
fathead minnow
green sunflsh
rainbow trout
rainbow trout
rainbow trout
NS
largemouth bass
sheepshead minnow
,
BCFb
5300-13,000
4500
4000-4900
5200-12.000
3800-4500
3400
13,000-20,000
-5000
14,000
35,000
16,200-18,500
21,900
5500
7762
12.000-20,000
8600
18,214-44,437
20,000
Biological
Half-I1fec
(days)
NR
NR
NR
NR
NR
>7
3.8
>7<21
NR
NR
NR
NR
NR
NR
>4<9
NR
Reference
Oliver and N11m1, 1983
Kenaga and Goring, 1980
KHano, 1978
Oliver and N11m1, 1983
KHano, 1978
Velth et al.. 1980
Oliver and N11m1, 1983
Kenaga and Goring, 1980
Kcnemann and Van Leeuwen,
1980
Koslan et al., 1981
Velth et al., 1979
VeHh et al., 1979
Velth et al., 1979
Neely et al., 1974
Oliver and N11m1, 1983
Kenaga and Goring, 1980
Laseter et al. . 1976
ParMsh et al., 1978
o
Ui
ro
co
-pv
Determined experimentally or by calculation from relative chromatographlc retention time
DT1ssue concentration/water concentration (1n flowing water)
C0epurat1on time for tissue concentration to decrease by one-half
dKenaga and Goring (1980) reported these data from various authors; therefore, each entry 1n a row may be from a different study.
eKonemann et al. (1979)
fBanerjee et al. (1980)
9Ch1ou et al. (1982)
NR = Not reported; NS = Not specified
-------
B1oaccumulat1on 1n aquatic species 1s a function of the total environ-
mental exposure of the organism Including both water and the food consumed.
Macek et al. (1979) showed, however, that uptake of 1,2,4-tMchlorobenzene
from the ambient water (bloconcentratlon) accounted for 93% of the total
body burden, while diet accounted for 6-7% of the 14C-1,2,4-tMchloroben-
zene measured 1n bluegllls, Lepomls macrochlrus, after 28 days of exposure.
Similar conclusions were reached by Laseter et al. (1976) using bass and
bluegllls exposed to hexachlorobenzene.
Although the chlorinated benzenes do bloaccumulate and establish tissue
concentrations 1n equilibrium with the environment (Kenaga and Goring, 1980;
Velth et al., 1980; Lu and Metcalf, 1975), the biological (referring to
Individual organisms) and ecological (referring to blomagnlf1cat1on) persis-
tence of the substance may be the more Important parameter. The longer bio-
logical half-life of persistent compounds 1s most likely a result of their
relative tissue-binding kinetics and the rate of their blotransformatlon.
Ware and West (1977) concluded that halogenatlon of a compound Increased Its
resistance to blotransformatlon. This, together with the high affinity for
adipose tissue, suggests that the chlorobenzenes are persistent compounds;
this 1s shown for fish 1n Table 5-5.
The extent of halogenatlon also affects the rate of depuration. Gup-
pies, PoeclHa retlculata. were exposed to a standardized mixture of six
chlorobenzenes for 19 days and then allowed to depurate for 9 weeks
(Konemann and Van Leeuwan, 1980). The ambient water concentration of each
chlorobenzene, the BCF and the slope of the elimination curve are shown in
lable 5-6. While the chlorobenzenes as a group are persistent, halogenatlon
Influences their rate of elimination.
1828A 5-17 03/22/84
-------
TABLE 5-6
B1oconcentrat1on Factor and Slope of the Elimination Curve for
Gupples (Poedlla retlculata) Exposed to Six Chlorinated Benzenes3
Compound
1 ,A-D1chlorobenzene
1 ,2,3-Tr1chlorobenzene
1 ,3,5-Tr1chlorobenzene
1 ,2,3,5-Tetrachlorobenzene
Pentachlorobenzene
Hexachlorobenzene
Average Concentra-
tion Measured In
Water (ng/ms.)
116
48
43
12
1.2
0.3
BCFb
l.BxlO3
1.3x10"
1.4x10*
7.2xl04
2.6xl05
2.9xlOs
Slope of
Elimination
Curve (day"1)0
1.00
0.45
0.40
0.28
0.18
0.062
aSource: Konemann and Van Leeuwan, 1980
Calculated on the basis of fat weight (average fat weight = 5.4%)
C0nly l,4-d1-and hexachlorobenzene had single-phase elimination curves;
the second-phase slopes for the other compounds are excluded for simplicity.
1828A
5-18
02/13/84
-------
The significance of biological persistence lies 1n the Increased time of
physiological exposure for an Individual organism and the greater probabil-
ity for human exposure via environmental media.
No studies were available on the bloaccumulatlon of the chlorobenzenes
In terrestrial food webs. There are, however, no Immediately apparent
reasons why the relationships between bloaccumulatlon and the physlcocheml-
cal parameters demonstrated for aquatic systems are not applicable to the
terrestrial environment. Generally, for air-breathing terrestrial species
such as humans, the atmospheric concentration of a compound 1s the primary
determinant of bloaccumulatlon because the frequency of air Intake 1s much
greater compared to the 1ngest1on of food or water. This was apparent from
the analysis of ambient air and household tapwater samples taken from nine
homes 1n the Love Canal area of Niagara Falls, New York (Barkley et al.,
1980). From these data, the expected total dally Intake of dlchloroben-
zenes by a 70 kg adult male for example, was nearly 300-fold greater from
air (0.119 mg/day) than from tapwater (3.36xlO~* mg/day). This topic 1s
discussed more extensively 1n Sections 4.3. and 4.4.
Although the chlorobenzenes are volatile compounds and Inhalation 1s the
expected primary route of human exposure, potentially high Intake by other
routes cannot be Ignored. Therefore, bloaccumulatlon and Internal exposure
are mult1factor1al parameters dependent upon the chlorinated benzene concen-
tration In each of three environmental compartments and upon the relative
rate of absorption and elimination for each compound.
5.4. SUMMARY
The chlorinated benzenes are a group of volatile compounds readily
evaporated to the atmosphere from soil and water. Point source releases of
the chlorinated benzenes are readily carried by prevailing winds and may be
1828A 5-19 02/13/84
-------
the primary source of measurable hexachlorobenzene In Industrially remote
areas, although there also may be concentration gradients around these point
sources. The high vapor pressure and low water solubility of these com-
pounds promotes their release to the atmosphere from open water systems or
their association with organic material that may either be Incorporated Into
sediments or flow out of the system. Soils, depending on their type, read-
ily evaporate chlorobenzenes from pore spaces to the atmosphere, or, depend-
ing on the relative affinity of the compound, release 1t as leachate.
Little Information 1s available on the fate of the chlorinated benzenes
In air, but one study concluded that the atmospheric residence time In-
creased with an Increase 1n chlorine substHuents. Laboratory studies with
smog chambers suggests photocatalysls may produce nitrobenzene, and nHro-
phenol or polychlorlnated blphenyls (01ll1ng et al., 1976; Kanno and Nojlma,
1979; Uyeta et al., 1976). The fate of the chlorobenzenes 1n water and soil
are similar, but the rates differ for each process (I.e., blodegradatlon,
loss to the atmosphere, accumulation 1n the biota, physical removal by
outflow or leaching, or sequestration of the unaltered compound).
The chlorobenzenes are I1poph1l1c compounds that bloaccumulate 1n animal
and human tissues from ambient air, water and food. The BCF (tissue concen-
tration/media concentration) 1s an Indicator of bloaccumulatlon and 1s
determined by physlochemlcal parameters such as the water solubility, the
octanol/water partition coefficient and the number of substHuent chlorine
atoms (Kenaga and Goring, 1980). Physiological exposure levels are deter-
mined by absorption, distribution, metabolism, elimination, and storage 1n
adipose tissue; thus, biologically persistent compounds, such as the chloro-
benzenes, may produce prolonged physiological exposures.
1828A 5-20 02/13/84
-------
6. ECOLOGICAL EFFECTS
As mentioned briefly 1n the previous chapters, chlorinated benzenes
occur 1n both the aquatic and terrestrial environments. The concentrations
of these compounds 1n some areas suggest that wildlife may be exposed to
higher levels of chlorinated benzenes than those encountered by humans.
Although aquatic and terrestrial organisms are exposed, no data are avail-
able on the toxic effects of chlorobenzenes at environmental concentrations
1n natural populations. Laboratory testing has shown that chlorobenzenes
have toxic effects on aquatic and terrestrial species and bloaccumulate In
exposed organisms.
6.1. EFFECTS ON THE AQUATIC ENVIRONMENT
Data on the effects of chlorinated benzenes on freshwater or marine
organisms 1n their natural environment were not available. Chlorobenzenes
have been shown to be acutely toxic to aquatic species 1n laboratory bio-
assays. The results of such acute toxldty bloassays can be used to deter-
mine relative tox1cH1es of the various chlorobenzenes to various species.
6.1.1. Effect on Freshwater and Marine F1sh. The acute toxldty of mono-
chlorobenzene has been reported for several species of freshwater and marine
fish (Table 6-1). The most sensitive species appears to be the rainbow
trout, Salmo galrdnerl, with 96-hour median lethal concentration (LC )
values ranging between 3-5 mg monochlorobenzene/9, (Brosier, 1972; Dow
Chemical Company, 1978b; Calamarl et al., 1983; Dallch et al., 1982). Blue-
gill sunflsh (Lepomls macrochlrus), fathead minnows (Plmephales promelas)
and gupples (Leblstes retlculatus) were moderately tolerant with mean
96-hour LC values ranging from 15.9-24.0, 31.5-33.9 and 45.5 mg/fc,
respectively (U.S. EPA, 1978; Pickering and Henderson, 1966). The goldfish,
Carasslus auratus. was the species most tolerant of monochlorobenzene with a
96-hour LC value of 51.62 mg/8, (Pickering and Henderson, 1966).
1829A 6-1 03/23/84
-------
TABLE 6-1
x> Acute ToxUHy Data for F1sh Species Exposed to Chlorinated Benzenes
3>
Compound Species Duration
(hour)
Monochlorobenzene rainbow trout 96
(Salmo galrdnerl )
24
8
96
96
48
bluegUl sunflsh 24
_, (Lepomls macrochlrus) 48
i 72
^ 96
96
24
48
96
24
96
fathead minnows 24
(Plmephales promelas)
48
96
24
S 4B
CO
\
S 96
no
\
Mean
Concentration
(mg/l)
3.58
1.8
5-10
3-5
4.7
4.1a
16.9
15.9
15.9
15.9
7.80
24.00
24.00
24.00
17.0
16.0
31.53
31.53
31.53
39.19
34.98
33.93
Method
constant-flow
NR
static
static
constant-flow
IRSA
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
Effect
t-^50
I~CSQ
LC] QQ
LC50
LD-50
LC50
LC50
50
50
None
LC50b
LC50b
LC50b
LC50
LC50
LC50b
LC50b
LC50b
I-CSQC
LC50c
LC50c
Reference
Dow Chemical Co.,
1978b
G1nger1ch and
Dallch, 1978
Brosler, 1972
Brosler, 1972
Dallch et al.,
1982
CalamaM et al. ,
1983
U.S. EPA. 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA. 1978
Pickering and
Henderson, 1966
Pickering and
Henderson, 1966
Pickering and
Henderson, 1966
Buccafusco et al. ,
1981
Buccafusco et al. ,
1981
Pickering and
Henderson, 1966
Pickering and
Henderson, 1966
Pickering and
Henderson, 1966
Pickering and
Henderson, 1966
Pickering and
Henderson, 1966
Pickering and
Henderson, 1966
oo
-------
TABLE 6-1 (cont.)
M>* II. . 1
TVS
Compound
Monochlorobenzene (cont.)
o->
i
to
l,2-01chlorobenzene
o
CO
CO
CD
Species
goldfish
(Carasslus auratus)
gupples
(Leblstes retlculatus)
sheepshead minnow
(Cyprlnodon vaMeqatus)
Brachydanlo rerlo
rainbow trout
(Sal mo galrdnerl )
blueglll sunflsh
(Lepomls macrochlrus)
fathead minnow
(Plmephales promelas)
Duration
(hour)
24
48
96
24
48
96
24
48
96
96
48
96
48
24
48
72
96
96
24
96
96d
96
48
96
Mean
Concentration
(mg/l)
73.03
56.00
51.62
45.53
45.53
45.53
>19.9
8.94
10.50
6.20
10.53
1.67
2.33
6.26
6.06
5.59
5.59
<3.20
6.3
5.6
27.0
57.0
76.3
57.0
Method
static
static
static
static
static
static
static
static
static
static
IRSA
constant-flow
IRSA
static
static
static
static
static
static
static
static
static
static
static
Effect
LC50b
LCsrjb
LC50b
LC50
LC50
LC50
^-^50
LCgQ
t-cso
None
LC50
LC50
LCso
IC5°
LC50
None
LCso
LC50
LC50
LC50
Lt-50
LC50
Reference
Pickering and
Henderson, 1966
Pickering and
Henderson, 1966
Pickering and
Henderson, 1966
Pickering and
Henderson, 1966
Pickering and
Henderson, 1966
Pickering and
Henderson, 1966
U.S. EPA. 1978;
HeUmuller et al.,
1981
Calamarl et al. ,
1983
Dow Chemical Co. ,
1978b
Calamarl et al. ,
1983
U.S. EPA. 1978
U.S. EPA. 1978
U.S. EPA. 1978
U.S. EPA, 1978
U.S. EPA, 1978
Buccafusco et al. ,
1981
Buccafusco et al . ,
1981
Dawson et al. , 1977
Curtis and Ward,
1981
Curtis et al..
1979
Curtis et al. ,
1979
-------
TABLE 6-1 (cont.)
-BJ
J3O
Compound
Species Duration
(hour )
Mean
Concentration Method Effect
(mg/i)
Reference
l,2-D1chlorobenzene (cont.)
tidewater sllverslde
(Menldla berylllna)
sheepshead minnow
(Cyprlnodon varlegatus)
96d
24
48
72
96
96
7.3
9.66-12.9
9.26
9.66
9.66
7.22
static
static
static
static
static
static
LC50
LC50
None
Dawson et al., 1977
U.S. EPA, 1978;
Heltmuller et al..
1981
Brachydanlo rerlo
48
6.8^
IRSA
CalamaH et al..
1983
1,3-D1chlorobenzene
blueglll sunflsh
(Lepomls roacrochlrus)
24
48
72
96
96
24
96
21.8
10.7
02
02
70
22.0
5.0
static
static
static
static
static
static
static
LC50
^50
LC^o
None
U.S.
U.S.
U.S.
U.S.
U.S.
EPA.
EPA.
EPA.
EPA.
EPA.
1978
1978
1978
1978
1978
Buccafusco et al.
1981
Buccafusco et al.
1981
,4-01chlorobenzene
fathead minnow
(Plmephales promelas)
sheepshead minnow
(Cyprlnodon varlegatus)
blueglll sunflsh
(Lepomls macrochlrus)
O
CO
ro
CO
CO
96
24
48
72
96
96
24
48
72
96
96
24
96
12.7
8.46
8.04
8.04
7.77
4.18
.54
.37
.37
.28
<2.80
4.5
4.3
static
static
static
static
static
static
static
static
static
static
static
static
static
LC50
LC50
LC50
LC50
LC50
None
LC50
None
Curtis and Ward,
1981
U.S. EPA. 1978;
Heltmuller et al.
1981
U.S. EPA. 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA. 1978
Buccafusco et al.
1981
Buccafusco et al.
1981
-------
TABLE 6-1 (cont.)
OS
Jg Compound Species
3»
l,4-D1chlorobenzene (cont.) fathead minnow
(Plmephales promelas)
sheepshead minnow
(Cyprlnodon varleqatus)
rainbow trout
(Salmo galrdnerl)
Brachydanlo rerlo
o^ 1,2,3-TMchlorobenzene rainbow trout
en (Salmo galrdnerl )
Brachydanlo rerlo
1,2,4-Trlchlorobenzene rainbow trout
Duration
(hour)
96
24
48
96
24
48
72
96
96
48
48
48
48
48
Mean
Concentration
(mg/l)
30.0
35.4
35.4
33.7
7.5-10.0
7.17
7.40
7.40
5.6
1.183
4.25a
0.713
3.13
1.953
Method
static
static
static
static
static
static
static
static
static
IRSA
IRSA
IRSA
IRSA
IRSA
Effect
Reference
LC5Q Curtis and Ward.
LCso
LCSO
LC50
LCso
LCso
LCso
LC50
None
LCso
LCSO
LCso
LCso
LCSO
1981
Curtis et al..
Curtis et al. ,
Curtis et al. ,
U.S. EPA. 1978
Heltmuller et
1981
Calamarl et al
1983
Calamarl et al
1983
Calamarl et al
1983
Calamarl et al
1983
Calamarl et al
1979
1979
1979
.
al..
* t
• t
• »
• t
• •
(Salmo galrdnerl)
Brachydanlo rerlo
48
6.33
IRSA
1983
Calamarl et al.,
1983
o
CO
rv>
CO
03
blueglll sunflsh
(Lepomls macrochlrus)
sheepshead minnow
(Cyprlnodon varleqatus)
24
48
72
96
96
24
96
24
48
72
96
96
109.0
13.0
3.59
3.36
<1.70
109.0
3.4
>46.8
>46.8
>46.8
21.4
14.6
static
static
static
static
static
static
static
static
static
static
static
static
LCSO
LC50
LCso
LCso
None
LCSO
LC50
LCso
LC50
LC50
LC50
None
U.S. EPA. 1978
U.S. EPA. 1978
U.S. EPA. 1978
U.S. EPA. 1978
U.S. EPA, 1978
Buccafusco et al. ,
1981
Buccafusco et al. ,
1981
U.S. EPA. 1978;
Heltmuller et al. ,
1981
-------
TABLE 6-1 (cont.)
CD
ffl
I
o
GO
o
\
CD
Compound
1 ,2,3.5-Tetrachlorobenzene
1 ,2,4,5-Tetrachlorobenzene
Pentachlorobenzene
Species
bluegUl sunflsh
(Lepomls macrochlrus)
sheepshead minnow
(Cyprlnodon varleqatus)
blueglll sunflsh
(Lepomls macrochlrus)
sheepshead minnow
(Cyprlnodon varleqatus)
blueglll sunflsh
(Lepomls macrochlrus)
Duration
(hour )
24
48
72
96
96
24
96
24
48
72
96
96
24
48
72
96
96
24
96
24
48
72
96
96
96
24
48
72
96
96
24
96
Mean
Concentration
(mg/l)
57.8
11.5
8.34
6.42
<1.70
59.0
6.4
>7.5
5.59
4.68
3.67
1.0
5.69
4.35
1.55
1.55
0.68
5.7
1.6
>1.80
0.90
0.84
0.84
0.32
0.33
2.27
0.55
0.30
0.25
<0.088
2.30
0.25
Method
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
f lowthrough
static
static
static
static
static
static
static
Effect
LC50
LC50
LCso
None
LC50
LC50
LC50
LC50
50
50
None
LC50
LCso
LCso
None
LCso
LCso
LC5Q
LCso
LC50
LC50
None
LCso
50
50
LCso
None
LCso
LC$o
Reference
U.S. EPA. 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
Buccafusco et al. ,
1981
Buccafusco et al. ,
1981
U.S. EPA, 1978;
Heltmuller et al.,
1981
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
Buccafusco et al. ,
1981
Buccafusco et al. ,
1981
U.S. EPA, 1978;
Heltmuller et al. .
1981
Ward et al., 1981
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA. 1978
U.S. EPA, 1978
Buccafusco et al . ,
1981
Buccafusco et al. ,
1981
-------
3D
ISO
Compound Species
Pentachlorobenzene (cont.) sheepshead minnow
( Cypr 1 nodon vaMeqatus)
Hexachlorobenzene largemouth bass
(Hlcropterus salmoldes)
sheepshead minnow
( Cypr 1 nodon vaMeqatus)
-^ plnflsh
(Lagodon rhomboldes)
rainbow trout
(Salmo galrdnerl)
Brachydanlo rerlo
aSoft water conditions: pH = 7.4; hardness = 320 mg CaCC
TABLE
Duration
(hour)
24
48
72
96
96
240
360
96
96
48
48
13/1; oxygen
6-1 (cont.)
Mean
Concentration
(mg/l)
>32.0
9.55
3.2-10.0
0.83
0.32
0.009-0.01
0.022-0.026
0.13
l.OC
<0.03a
<0.03a
= >70X; temperature =
Method
static
static
static
static
static
static
static
constant-flow
constant-flow
IRSA
IRSA
15'C for trout and
Effect
LC50
LC50
LCso
None
None
None
None
None
LC50
LC50
23°C for
Reference
U.S. EPA. 1978;
Heltmuller et al. ,
1981
Laska et al.. 1978
Laska et al., 1978
Parrlsh et al. ,
1974
Parrlsh et al. ,
1974
Calamarl et al. ,
1983
Calamarl et al. ,
1983
Brachydanlo
o
u>
no
CO
CO
bSoft water conditions: pH = 7.5; alkalinity = 18 mg/l; hardness = 20 rag/l
cHard water conditions: pH = 8.2; alkalinity = 300 mg/l; hardness = 360 mg/l
^Estimated based on 24, 48, 72 and 96-hour toxldty tests
eNom1nal concentration; because of solubility, actual concentration would be less
NR = Not reported
-------
The marine sheepshead minnow, CypMnodon varleqatus. was relatively sensi-
tive with a 96-hour LC value of 10.5 mg/8, (U.S. EPA, 1978; Heltmuller
et al., 1981).
The acute toxldty of 1,2-d1chlorobenzene was studied 1n several fresh-
water and marine fish (see Table 6-1). Rainbow trout, S. qalrdnerl. was the
most sensitive species reported with an LC value of 1.67 mg/a. follow-
ing a 96-hour exposure (Dow Chemical Company, 1978b). The U.S. EPA (1978)
and Buccafusco et al. (1981) reported 96-hour LC values near 5.6 mg/a.
for the blueglll sunflsh, L. macrochlrus. while Dawson et al. (1977)
reported a value of 27.0 mg/8. for this species. The fathead minnow, P.
promelas. was the most resistant species tested, having a 96-hour LC
value of 57.0 mg/si (Curtis et al., 1979; Curtis and Ward, 1981). Two
marine species, the tidewater sllverslde (Men1d1a berylllna) and the sheeps-
head minnow (C. varleqatus). were moderately sensitive with 96-hour LC
values of 7.3 and 9.7 mg/a, respectively (Dawson et al., 1977; U.S. EPA,
1978; Heltmuller et al., 1981).
The 1,3- Isomer of dlchlorobenzene was tested for acute toxldty In two
species of freshwater fish and a single marine species. The 24, 48, 72 and
96-hour LC values for blueglll sunflsh, L. macrochlrus. were 21.8, 10.7,
5.02 and 5.02 mg 1,3-d1chlorobenzene/a, respectively (U.S. EPA, 1978;
Buccafusco et al., 1981). The no-observed-effect level (NOEL) was 1.7
mg/8, 1n the blueglll (U.S. EPA, 1978). The fathead minnow, P. promelas.
had a static 96-hour LC5Q value of 12.7 mg 1,3-d1chlorobenzene/a (Curtis
and Ward, 1981). In the marine species, sheepshead minnow (C. varlegatus).
24, 48, 72 and 96-hour LC values were 8.46, 8.04, 8.04 and 7.77 mg/a,
J VJ
respectively. The NOEL was 4.18 mg/a (U.S. EPA, 1978; Heltmuller et al.,
1981).
1829A 6-8 03/23/84
-------
Rainbow trout, blueglll sunflsh, fathead minnows and sheepshead minnows
were the species tested to study the static acute toxldty of 1,4-d1chloro-
benzene. Rainbow trout, S. galrdnerl. was the most sensitive species
tested, with 48-hour LC values of 1.18 mg/a, {Calamarl et al., 1983).
The blueglll sunflsh (L. macrochlrus) showed 24, 48, 72 and 96-hour LC5Q
values of 4.54, 4.37, 4.37 and 4.28 mg/8, (U.S. EPA, 1978; Buccafusco et
al., 1981). The NOEL for this species was reported to be <2.8 mg l,4-d1~
chlorobenzene/ft (U.S. EPA, 1978). The 24, 48, and 96-hour static LC5Q
values for fathead minnows (P. promelas) were 35.4, 35.4 and 33.7 mg/l,
respectively (Curtis et al., 1979). The marine sheepshead minnow, C.
varlegatus. was Intermediate 1n sensitivity to 1,4-d1chlorobenzene, having a
96-hour LC5Q of 7.4 mg/8, and a NOEL of 5.6 tng/a. (U.S. EPA, 1978;
HeHmuller et al., 1981).
1,2,4-Trlchlorobenzene has been tested for acute toxldty to fish
species. The 48-hour LCcn value for rainbow trout, S_. galrdnerl. was 1.95
bu
mg/a. (CalamaM et al., 1983). In the blueglll sunflsh (L. macrochlrus)
estimated LC,-ns, based on nominal concentrations, were reported for 24,
48, 72 and 96-hour exposures at 109.0, 13.0, 3.59 and 3.36 mg l,2,4-tr1-
chlorobenzene/a (U.S. EPA, 1978; Buccafusco et al., 1981). The NOEL was
<1.7 mg/a for the sunflsh. The sheepshead minnow, C_. varlegatus. was more
tolerant with 24, 48 and 72-hour LC values >46.8 mg/8. and the 96-hour
LC5Q value of 21.4 mg/a. The NOEL for this marine species was 14.6
mg/il (U.S. EPA, 1978; HeHmuller et al., 1981). For 1,2,3-tMchloroben-
zene, rainbow trout, S. qalrdnerl. showed a 48-hour LC,_0 value of 0.71
mg/a (Calamarl et al., 1983), and 1s thus more aquatlcally toxic than the
1,2,4- Isomer. The correspor
mg/8, (Calamarl et al., 1983).
1,2,4- Isomer. The corresponding LCrn value for Brachydanlo rerlo was 3.1
bu
1829A 6-9 03/23/84
-------
The toxIcHy of only 1,2,3,5- and 1,2,4,5-tetrachlorobenzene has been
tested 1n fish. These two Isomers differ dramatically In their lethality to
blueglll sunflsh and sheepshead minnows. The 24, 48, 72 and 96-hour LC™
values for the 1,2,3,5- Isomer 1n bluegllls (I., macrochlrus) and sheepshead
minnows (£. varlegatus) were 57.8, 11.5, 8.34 and 6.42 mg/a. and >7.5,
5.59, 4.68 and 3.67 mg/a, respectively (U.S. EPA, 1978; Buccafusco et al.,
1981; Heltmuller et al., 1981; Ward et al., 1981). The NOELs for the
blueglll and sheepshead minnow were <1.70 and 1.0 mg 1,2,3,5-tetrachloro-
benzene/a,, respectively. The 1,2,4,5- Isomer was, 1n some cases, 10-11
times more lethal to the fish species tested. For example, the 24, 48, 72
and 96-hour LC™ values 1n the blueglll sunflsh were 5.69, 4.35, 1.55 and
1.55 mg/a.. In the sheepshead minnow, the L.CCQ values ranged from
>1.80-0.33 for 24 through 96-hour exposures (see Table 6-1 for comparison)
(U.S. EPA, 1978; Heltmuller et al., 1981; Ward et al., 1981). NOELs for the
1,2,4,5- Isomer were reported to be 0.68 and 0.32 mg/a. for blueglll
sunflsh and sheepshead minnows, respectively.
The acute toxlclty of pentachlorobenzene was studied 1n the freshwater
blueglll sunflsh and the marine sheepshead minnow (U.S. EPA, 1978; Bucca-
fusco et al., 1981; Heltmuller et al., 1981). The static LC5Q values for
24, 48, 72 and 96-hour exposures were 2.27, 0.55, 0.30 and 0.25 mg/a. for
the bluegUl sunflsh (L. macrochlrus) and >32.0, 9.55, 3.2-10.0 and 0.83
mg/J. for the sheepshead minnows (C,. varleqatus). NOELs for blueglll sun-
fish and sheepshead minnows were <0.088 and 0.32 mg pentachlorobenzene/a.,
respectively.
Because of the low water solubility of hexachlorobenzene, acute toxlclty
testing of this compound has been conducted at low concentration levels.
1829A 6-10 03/02/84
-------
Largemouth black bass, Hlcropterus salmoldes, exposed for 10 days at 9-10
pg/8, or exposed for 15 days at 22-26 pg/l, showed no toxic effects
(Laska et al., 1978). Sheepshead minnows, C. varlegatus, exposed at 0.13
mg/s, and plnflsh, Lagodon rhomboldes, exposed to a nominal concentration
of 1.0 mg/i (actual concentration would be less because of low aqueous
solubility) for a 96-hour period showed no toxic effects (Parrlsh et al.,
1974). But rainbow trout, S. galrdnerl. and Brachydanlo rerlo showed
48-hour LC values of <0.03 mg/l (Calamarl et al., 1983).
Subchronlc toxldty testing has been conducted on monochlorobenzene 1n
rainbow trout, S. galrdnerl (Oallch et al., 1982). Groups of fish were
exposed to 2.1 or 2.9 mg monochlorobenzene/8. for 15 or 30 days. Treated
fish did not accept food during at least the first 15 days of treatment.
Neither concentration of monochlorobenzene resulted In any deaths during the
exposure periods, but loss of equilibrium was reported 1n most treated fish.
Liver toxldty, determined by enzyme levels, and hlstologlcal hepatic
changes were reported 1n trout treated at both exposure levels (Dallch et
al., 1982).
Studies conducted by the U.S. EPA (1978, 1980a) resulted 1n chronic
toxldty values (NOELs) for many of the chlorinated benzenes 1n fathead
minnows and/or sheepshead minnows (Table 6-2).
During b1oaccumulat1on testing with the blueglll sunflsh, I., macro-
chlrus, fish were exposed to 1,2-d1chlorobenzene (7.89 yg/8.). l,3-d1~
chlorobenzene (107.0 ug/l) and 1,4-d1chlorobenzene (10.1 pg/a) for
14 days. Similarly, 1,2,4-tr1chlorobenzene (2.87 vg/l), 1,2,3,5-tetra-
chlorobenzene (7.72 yg/l) and pentachlorobenzene (5.15 yg/l) were
tested for 28 days 1n the blueglll. No deaths or toxic effects were
reported for any of the chlorinated benzenes at the exposure levels tested
(Barrows et al., 1980).
1829A 6-11 03/23/84
-------
CD
TABLE 6-2
Chronic Toxlcity Values of Chlorinated Benzenes 1n Fish
Chemical
1 ,2-Dichlorobenzene
1 ,3-Oichlorobenzene
T 1 ,4-D1chlorobenzene
1 ,2,4-Trichlorobenzene
1 ,2,3,4-Tetrachlorobenzene
1 ,2,4,5-Tetrachlorobenzene
Species
fathead minnow
(Pimephales promelas)
fathead minnow
(Pimephales promelas)
fathead minnow
(Pimephales promelas)
fathead minnow
(Pimephales promelas)
sheepshead minnow
(Cyprinodon variegatus)
fathead minnow
(Pimephales promelas)
sheepshead minnow
(Cyprinodon varieqatus)
Chronic Value*
2000
1510
763
286
705
222
318
129
Range
1600-2500
1000-2270
560-1040
200-410
499-995
150-330
245-412
92-180
Reference
U.S.
U.S.
U.S.
U.S.
U.S.
U.S.
U.S.
U.S.
EPA,
EPA,
EPA,
EPA,
EPA,
EPA,
EPA,
EPA,
1978
19803
1980a
1978
1980a
1978
1980a
1978
o
CO
o
ro
CO
*NOELs
-------
Limited data are available on the pharmacoklnetlcs of chlorinated
benzenes 1n fish. Uptake of 1,2,4-tr1chlorobenzene from the water (0.012
mg/i) was rapid 1n the rainbow trout, S. galrdnerl. with bile and liver
concentrations exceeding 100 times the water levels within hours (Melancon
and Lech, 1980). N11m1 and Cho (1980) reported that rainbow trout absorbed
and accumulated hexachlorobenzene from their diet and body levels could
Increase 15 vg/kg body weight/day 1n a dose-dependent manner. Later,
Oliver and N11m1 (1983) reported evidence Indicating that all chlorinated
benzenes studied (l,2-d1, l,3-d1, l,4-d1, l,3,5-tr1, 1,2,4-trl, l,2,3-tr1,
1,2,4,5-tetra, 1,2,3,4-tetra, penta- and hexachlorobenzene) could be
absorbed from the aqueous environment. ZHko and Hutzlnger (1976) reported
the uptake and accumulation of hexachlorobenzene from food or water 1n
juvenile Atlantic salmon, Salmo salar.
Monochlorobenzene seems to be metabolized by the liver since liver
toxldty, Including degeneration of hepatocytes and necrosis, was reported
1n treated rainbow trout (61nger1ch and Dallch, 1978). A modeling study by
Lu and Metcalf (1975) suggested that chlorobenzene 1s metabolized to o- and
p-chlorophenol 1n the mosquito fish, Gambusla afflnls.
Studies on the metabolism and blotransformatlon of 1,2,4-tr1chloro-
benzene 1n rainbow trout (S. galrdnerl) and carp (Cyprlnus carplo) suggested
that conjugated metabolites occur 1n the liver and bile (Melancon and Lech,
1980). A hepatic mixed-function oxldase Inducer (p-naphthoflavone)
elevates the hepatic and biliary levels of blotransformatlon products of
1,2,4-tMchlorobenzene. In the mosquito fish, G. afflnls. absorbed hexa-
chlorobenzene 1s predominantly unchanged, but two unidentified metabolites
were reported (Lu and Metcalf, 1975).
1829A 6-13 03/23/84
-------
Accumulated chlorinated benzenes and/or their metabolites seem to be
distributed throughout the body 1n fish. The highest concentrations have
been detected 1n the bile, liver and muscle (Melancon and Lech, 1980). The
bloconcentratlon of chlorinated benzenes Increased as the degree of chloM-
natlon of the test compound Increased (Oliver and N11m1, 1983). Bloconcen-
tratlon factors (BCFs) for many of the chlorinated benzenes 1n gupples
(Poedlla retlculata) and rainbow trout (S. galrdnerl) are shown 1n Table
6-3 (Konemann and van Leeuwen, 1980; Oliver and N11m1, 1983). More complete
data on BCFs 1n fish are reported 1n Section 5.3 of this document.
The excretion rate of chlorinated benzenes 1n fish 1s related to the
extent of chlorlnatlon of the compound. Konemann and van Leeuwen (1980)
reported that 1,4-d1chlorobenzene 1s excreted within several days, while
trlchlorobenzenes required nearly 25 days, tetrachlorobenzene nearly 50
days, and penta- and hexachlorobenzene required >50 days for elimination.
After termination of exposure, 1,2,4-tr1chlorobenzene and metabolites are
eliminated 1n two stages. The first had a half-life of elimination of 0.4
days, while the second was eliminated more slowly (t = 50 days). In
comparison, Branson et al. (1975) reported half-lives for elimination of
dlchlorobenzGne and hexachlorobenzene to be 1.1 and 12.1 days, respectively.
Sanborn et al. (1977) estimated the half-life for elimination of hexachloro-
benzene 1n the green sunflsh, L.. cyanellus. to be 8.0-19.6 days. The
longest time was for elimination from the liver. The biological half-life
of hexachlorobenzene was estimated to be 7 months to several years 1n
rainbow trout (N11m1 and Cho, 1981).
6.1.2. Effect on Aquatic Crustaceans. In addition to fish, freshwater
and marine crustaceans, which are an Important element 1n aquatic food
chains, are exposed to chlorobenzenes 1n the environment (Grzenda et al.,
1829A 6-14 03/23/84
-------
TABLE 6-3
Bloconcentratlon Factors of Some Chlorinated Benzenes 1n Two Fish Species
Species Compound
Rainbow trout l,2-d1-
Salmo qalrdnerl
1,3-dl-
l,4-d1-
1,3,5-tM-
l,2,4-tr1-
l,2,3-tr1-
1,2,4,5-tetra-
1,2,3,4-tetra-
penta-
hexa-
Guppy l,4-d1-
Poedlla retlculata l,2,3-tr1-
l,3,5-tr1-
1,2,3,5-tetra-
penta-
hexa-
Exposure
Level
(pg/O
47.0
940.0
28.0
690.0
28.0
670.0
2.3
45.0
3.2
52.0
4.3
72.0
1.0
21.0
1.4
26.0
0.34
9.3
0.32
8.0
116.0
48.0
43.0
12.0
1.2
0.3
BCF Reference
270 Oliver and N11m1,
560 1983
420
740
370
720
1,800
4,100
1,300
3,200
1,200
2,600
5,300
13,000
5,200
12,000
13,000
20,000
12,000
20,000
1 ,800 Konemann and
13,000 van Leeuwen, 1980
14,000
72,000
260,000
290,000
1829A
6-15
03/02/84
-------
1964). Laboratory testing of the chlorinated benzenes has provided acute
toxldty data for several species of crustaceans (Table 6-4).
The U.S. EPA (1978) reported most of the available data 1n which mono-,
l,2-d1-, l,3-d1-, l,4-d1-, 1,2.4-tM-. 1,2,3,5-tetra-, 1,2,4,5-tetra- and
pentachlorobenzene tox1c1t1es were tested 1n the water flea (Daphnla magna)
and the mysld shrimp (Mys1dops1s bahla). Other available studies on
specific chlorinated benzenes tested 1n specific species were noted 1n Table
6-2. Generally, the more chlorinated benzenes appear to be more toxic. For
example, the 96-hour LC^ values 1n mysld shrimp were 16.4, 1.97, 0.34 and
0.16 mg/8. for mono-, l,2-d1-, 1,2,3,5-tetra- and pentachlorobenzene,
respectively. Data on the toxldty of the 1,2,3,5- and 1,2,4,5-tetrachloro-
benzenes Indicate that, unlike that 1n fish, the 1,2,3,5- Isomer 1s more
toxic. Because of the very low solubility of hexachlorobenzene 1n aqueous
solutions, data on the toxldty of this compound are limited. One study
(Laska et al., 1978) reported no toxic effects 1n crayfish, Procambarus
clark11. exposed (unspecified Interval) to a saturated aqueous solution of
hexachlorobenzene (estimated to be -0.02 mg/8,). The 24-hour Immobiliza-
tion concentrations of several chlorobenzenes for water fleas, Daphnla
magna, using the AFNOR test were: monochlorobenzene (4.3 mg/l);
l,2-d1chlorobenzene (0.78 mg/8,); 1,4-d1chlorobenzene (<0.03 mg/2.)
(Calamarl et al., 1983).
6.1.3. Embryotoxlc and Reproductive Effects. Wild Atlantic salmon (Salmo
salar) eggs, collected from different sites, contained different levels of
hexachlorobenzene (0.086, 0.132, 0.142 and 0.159 Pg/g llpld 1n eggs). No
correlation between hexachlorobenzene levels and egg-hatchabllHy was demon-
strated (ZHko and Saunders, 1979). Eggs also contained other environmental
contaminants such as PCBs and organochloMde pesticides.
1829A 6-16 03/23/84
-------
00
»o
CD
TABLE 6-4
Acute Toxldty Data for Crustaceans Exposed to Chlorinated Benzenes
Compound
Species
Mean
Duration Concentration
(hour) (tng/l)
Method
Effect
o
CO
o
\
CD
Reference
lochlorobenzene water flea
(Daphnla maqna)
mysld shrimp
(Hys1dops1s bahla)
!-D1chlorobenzene water flea
(Daphnla magnal
mysld shrimp
(Mys1dops1s bahla)
grass shrimp
(Palaemonetes puglo)
'-Dlchlorobenzene water flea
(Daphnla maqna)
mysld shrimp
(Hys1dops1s bahla)
24
48
48
24
24
48
72
96
96
24
48
48
24
24
48
72
96
96
24
48
96
96
24
48
48
24
48
72
96
96
140.0
86.0
10.0
4.3
24.7
24.7
24.7
16.4
<11.1
2.44
2.44
0.36
0.78
4.75
4.52
3.88
1.97
<1.29
14.3
10.3
9.4
10.4
47.8
28.1
6.0
7.31-13.06
5.14
4.06
2.85
<1.30
static
static
static
AFNOR
static
static
static
static
static
static
static
static
AFNOR
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
LC50
None
iCso
"50
LC50
"50
None
LC50
LCso
None
50
50
50
50
50
None
"50
"50
LCso
"50
50
50
None
"50
"50
"50
"50
None
U.S. EPA, 1978;
LeBlanc. 1980
Calamarl et al. ,
1983
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA. 1978;
LeBlanc. 1980
Calamarl et al. .
1983
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA. 1978
U.S. EPA, 1978
U.S. EPA, 1978
Curtis et al.,
1979
Curtis et al. ,
1979
Curtis et al.,
1979
Curtis and Ward,
1981
U.S. EPA, 1978;
LeBlanc, 1980
U.S. EPA, 1978
U.S. EPA. 1978
U.S. EPA. 1978
U.S. EPA. 1978
U.S.- EPA, 1978
-------
TABLE 6-4 (cont.)
cc
•N;
1C
I
CD
O
CO
o
PO
CD
Compound
1 ,4-D1chlorobenzene
1 ,2,3-TMchlorobenzene
1 ,2,4-Trlchlorobenzene
1 ,3,5-TMchlorobenzene
1 ,2,3,5-Tetrachlorobenzene
Species
water flea
(Daphnla magna)
raysld shrimp
(Hys1dops1s bahla)
grass shrimp
(Palaemonetes puqlo)
water flea
(Daphnla magna)
water flea
(Daphnla magna)
mysld shrimp
(Mysldopsls bahla)
brine shrimp
(Artemla sallna)
water flea
(Daphnla magna)
mysld shrimp
(Hys1dops1s bahla)
Duration
(hour)
24
48
46
24
24
48
72
96
96
48
96
96
24
24
48
48
24
24
48
72
96
96
168
24
48
48
24
48
72
96
96
Mean
Concentration
(mg/l)
41.5
11.0
0.68
1.6
5.6-10.0
5.35
4.31
1.99
<1.0
129.2
69.0
60.0
0.35
114.0
50.2
<2.4
1.2
>1.46
>1.46
0.76
0.45
0.09
10.0
18.1
9.71
<1.1
0.96
0.36
0.34
0.34
0.10
Method
static
static
static
AFNOR
static
static
static
static
static
static
static
static
AFNOR
static
static
static
AFNOR
static
static
static
static
static
static
static
static
static
static
static
static
static
static
Effect
LC50
LC50
None
IC50
LC50
LC50
LC50
LC50
None
t-cso
LC50
LC50
IC50
LC50
LC50
None
IC50
LC50
LC50
LC50
LC50
None
LC100
LC50
LC50
None
LC50
LC50
LC50
LC50
None
Reference
U.S. EPA, 1978;
LeBlanc. 1980
Calamarl et al. ,
1983
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
Curtis et al.,
1979
Curtis et al. ,
1979
Curtis and Hard,
1981
Calamarl et al. ,
1983
U.S. EPA, 1978;
LeBlanc. 1980
Calamarl et al. ,
1983
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA. 1978
U.S. EPA, 1978
Grosch, 1973
U.S. EPA, 1978;
LeBlanc, 1980
U.S. EPA, 1978
U.S. EPA, 1978
U.Sr EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
-------
as
TABLE 6-4 (cent.)
cr>
_^
us
Compound Species
1 ,2,4,5-Tetrachlorobenzene water flea
(Daphnla roagna)
mysld shrimp
(Hysldopsls bahla)
Pentachlorobenzene water flea
(Daphnla magna)
mysld shrimp
(Hysldopsls bahla)
Hexachlorobenzene water flea
(Daphnla magna)
swamp crayfish
(Procambarus dark11)
shrimp
(Crangon septemsplnosa)
Duration
(hour )
24
48
48
24
48
72
96
96
24
48
48
24
48
72
96
96
24
NR*
96
Mean
Concentration
(mg/l)
>530.0
>530.0
320.0
3.2-5.6
1.99
1.48
1.48
0.6
17.2
5.28
1.3
0.75
0.72
0.24
0.16
<0.06
<0.03
saturated*
0.0072
Method
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
AFNOR
static or
f lowthrough*
static
Effect
LC50
LC50
None
LC50
LC50
LCSO
LC50
None
LC50
LC50
None
LC50
LC50
LC50
LC50
None
IC50
No toxic
effects
No mortality
Reference
U.S. EPA. 1978;
LeBlanc, 1980
U.S. EPA. 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA. 1978
U.S. EPA, 1978;
LeBlanc, 1980
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
CalamaM et al. ,
1983
Laska et al..
1978
HcLeese and
Metcalfe, 1980
*Tox1c1ty testing was conducted for an unspecified period with a saturated aqueous solution of hexachlorobenzene 1n both static and flowthrough
systems.
o
to
ro
NR = Not reported
Lethal concentration for SOX of animals;
= Immobilization concentration for 50X of animals
00
-------
The toxic effects of monochlorobenzene on egg and embryo development
were studied 1n the laboratory with largemouth bass (Hlcropterus salmoldes),
goldfish (Carasslus auratus) and rainbow trout (Salmo galrdnerl) using a
flowthrough system with both hard (200 mg/8. CaCO ) and soft {50 mg/8.
O
CaCOJ water (B1rge et al., 1979). WHh trout, exposure to 0.09, 0.31,
O
1.60, 4.27 and 32.0 mg monochlorobenzene/a. was Initiated 20 minutes after
fertilization and continued for 16 days (hatching time for trout 1s 23
days). Complete lethality of the trout embryos occurred at all monochloro-
benzene concentrations within the exposure period 1n hard and soft water
conditions (Table 6-5). The LC for trout embryos was therefore reported
to be <0.09 mg/8. (B1rge et al., 1979). Largemouth bass embryos/larvae
were exposed 1-2 hours postfertHUatlon through hatching until 4 days
posthatchlng. (Average hatching time for bass 1s 3.5 days.) Chlorobenzene
concentrations ranged from 0.013-27.3 mg/8. for soft water and 0.009-23.2
mg/8, for hard water conditions. Percent hatchabUHy was reduced to 72,
25 and 4% of controls at 0.15, 3.10 and 23.2 mg/8., respectively, 1n hard
water. Percent survival of bass larvae at 4 days posthatchlng was 80, 60
and 24% after exposure to 0.013, 0.038 and 0.16 mg monochlorobenzene/8.,
respectively, 1n soft water conditions. The LC value at 4 days post-
hatching for bass larvae was reported to be 0.05-0.06 mg/8., while the
LCcn value for embryos exposed until hatching was 0.34-0.39 mg/8. (see
DU
Table 6-5). Goldfish, C. auratus. were more tolerant to monochlorobenzene
exposure during development. (Average hatching time for goldfish Is 4
days.) The LC__ values for embryos exposed until hatching and embryos/
larvae exposed until 4 days post-hatching ranged from 2.37-3.48 mg/8. and
0.88-1.04 mg/l, respectively (see Table 6-5). Abnormal bass larvae
1829A 6-20 03/23/84
-------
TABLE 6-5
Embryo-Larval Toxldty of Monochlorobenzene to Goldfish, Largemouth Bass
and Rainbow Trout In Soft and Hard Water3
Soft Water
(50 mg/l as CaC03>
Species
Goldf1shb
Largemouth bassc
Rainbow trout**
aSource: Blrge et
Exposure 1n
Days Beyond
Egg Hatching
0
4
0
4
£/
al., 1979
(mg/l)
3.48
0.88
0.34
0.05
<0.09
95%
Confidence
Limits
3.08-3.87
0.67-1.12
0.22-0.51
0.04-0.07
NA
Hard Water
(200 mg/l as CaC03)
LC50
(mg/l)
2.37
1.04
0.39
0.06
<0.09
95%
Confidence
Limits
1.96-2.86
0.86-1.25
0.25-0.58
0.04-0.08
NA
bRequ1re ~4 days from spawning to hatching; thus, exposure of the
hatched larvae for 4 additional days resulted 1n a total of 8 days of
continuous exposure.
cRequ1re -3.5 days from spawning to hatching; thus, exposure of the
hatched larvae for 4 additional days resulted In a total of 7.5 days of
continuous exposure.
dRequ1re -23 days from spawning to hatching; all exposed embryos were
dead by 16 days after fertilization.
NA = Not applicable
1829A
6-21
03/02/84
-------
occurred In 2, 13, 42 and 100% of those hatching after exposure to 0.04,
0.15, 3.1 and 23.2 mg/8,, respectively, during embryonic development.
Abnormal goldfish larvae were less prevalent (B1rge et al., 1979).
The embryo and larval toxldty of 1,2,4,5-tetrachlorobenzene was tested
In sheepshead minnows, C. varleqatus. Within 4 hours after assurance of
fertilization, embryos were exposed to 0.06, 0.09, 0.18, 0.30 and 0.52 mg
1,2,4,5-tetrachlorobenzene/a, until hatching; thereafter, exposure of
larval and juvenile fish was continued for an additional 28 days. Hatching
success of embryos was not significantly decreased at any exposure level.
Juvenile mortality was significantly (p<0.05) Increased In fish exposed to
>0.18 mg 1,2,4,5-tetrachlorobenzene/a, (Table 6-6). The maximum acceptable
toxicant concentration (MATC) for embryos and juvenile sheepshead minnows
exposed to 1,2,4,5-tetrachlorobenzene was estimated to range between
0.09-0.18 mg/8..
The embryo and larval toxldty of trlchlorobenzene {Isomer not speci-
fied) was studied 1n American oysters (Crassostrea vlrglnlca) and the hard
clam (Mercenarla mercenaMa) (Davis and Hindu, 1969). Exposure which
commenced soon after fertilization and embryo development was determined 48
hours later. To determine larval survival, 2-day-old larvae (hatched under
normal conditions) were exposed for 10 days (for clams) or 12 days (for
oysters) before quantitative sampling. At 1.0 and 10.0 mg trIchloroben-
zene/8., egg survival and normal embryo development 1n oysters was 59 and
21%, respectively, of control cultures. In clams treated with 1.0 and 10.0
mg tMchlorobenzene/8., embryo development was reduced to 72 and 58% of
controls. Survival of clam larvae exposed to 1.0 and 10.0 mg trlchloroben-
zene/l was 108 and 69% of controls, respectively, with no change 1n larval
length. Based on toxlclty data, Davis and Hindu (1969) reported a 48-hour
1829A 6-22 03/02/84
-------
TABLE 6-6
Results of l,2,4,5-Tetrachloroben2ene Tests with Embryo to Juvenile
Sheepshead Minnows 1n Continuous-Flow Natural Seawatera
Nominal
Concentration
(mg/a)
Control
Solvent control
0.12
0.25
0.5
1.0
2.0
Measured
Concentration'1
(mg/l)
ND
ND
0.06+0.04
0.09+0.04
0.18±0.07
0.30+0.16
0.52+0.33
Hatching
Success
(X)
84
85
76
81
91
83
67
Juvenile
Mortality0
(X)
21
25
16
41
54d
79d
98d
Standard Length
of Juveniles
(mm)
H±2
12+3
10+3
12+2
10+3
12+1
12+0e
aSource: Ward et al., 1981
bValues expressed as mean +_ standard deviation
cAt 28 days after hatching
dS1gn1fIcantly greater than control at p<0.05
eOnly one fish survived: the 96-hour LC50 for Juveniles was 0.33 mg/8,
with 9554 confidence limits of 0.12-0.94 mg/l.
ND = Not detectable (<0.007 mg/H)
1829A
6-23
03/02/84
-------
LC50 of 3'13 mg/a for ovster embryos and 48-hour and 12-day LC5Q
values of >10.0 mg/8. for clam embryos and larvae.
The effects of 1,3,5-tr1chlorobenzene on the reproductive performance 1n
brine shrimp, Artemla sallna. were reported by Grosch (1973). Ten pairs of
adult shrimp were exposed to 10 ppm 1,3,5-tMchlorobenzene for 24 hours and
studied for their lifetime for reproductive performance. The llfespan of
treated adult females was significantly (p<0.05) reduced. The number of
broods, number of zygotes, and larval survival rate were all significantly
reduced 1n exposed cultures (Table 6-7). The author discussed the possi-
bility that brood number and zygote number were related to the decreased
Hfespan of adult females, but discounted this as the sole cause after
computations showed a decrease 1n the brood size (Grosch, 1973). Cultures
of Artemla sallna that were continuously exposed to 10 mg 1,3,5-tr1chloro-
benzene/8, survived <1 week and produced no viable embryos.
6.1.4. Effect on Aquatic Plants. The 96-hour EC (effective concen-
tration for 50% of the algae to show the effect) for reduced chlorophyll a
content 1n the freshwater algae, Selenastrum caprlcornutum. treated with
monochlorobenzene was 232 mg/8, (Table 6-8). The 96-hour ECrn for 1nh1-
bU
bltlon of growth and the reported NOEL were 224 and <111 mg/a., respec-
tively (U.S. EPA, 1978). (For more complete toxldty data for algae refer
to Table 6-8.). Toxldty of 1,2-, 1,3- and 1,4-d1chlorobenzene was somewhat
varied when comparing 96-hour EC values for reduced chlorophyll content
of 91.6, 179 and 98.1, respectively. The general trend of Increasing
toxldty with Increased chlorine substitution 1s seen with 1,2,4-trUhloro-
benzene, tetrachlorobenzenes and pentachlorobenzene (see Table 6-8). The
1,2,3,5- Isomer of tetrachlorobenzene appears to be 2- to 3-fold more toxic
than the 1,2,4,5- Isomer 1n this freshwater algae, S. caprlcornutum. The
1829A 6-24 03/23/84
-------
TABLE 6-7
Adult Llfespan and Reproductive Performance of Brine Shrimp
Exposed to !,3,5-Tr1chlorobenzenea»b
Brine
Solution
Controls
Acetone
Controls
Exposed to
l,3,5-Tr1-
chlorobenzene
Adults:
Survival (1n days)
Males0
r -, d
Females
Number of broods (per pair)
49.6+4.0
50.0±5.0
11.31-1.6
47.6+4.0
50.H5.5
11.8+1.6
44.2+3.8
37.6+4.2
5.3+0.8
Offspring:
Total number of zygotes produced
Cysts produced (%)
Cysts hatched (%)f
Survival of larvae (%)
Sex ratio (no. males/no, females)
Adaptive values (ratio of average
no. of matured offspring per pair
exposed to 1,3,5-tMchlorobenzene/
average no. of matured offspring
per pair 1n acetone controls)^
1828
29.0
46+5
76.3+5.0
0.91
1884
30.6
48+7
75.6+4.7
0.94
1.00
456
11.4
18ilO
30.3±11.5
0.82
0.11
aSource: Grosch, 1973
bTests performed with 10 mating pairs exposed at 10 mg/l for 24 hours;
each pair then returned to separate fresh brine solutions.
cControl and treatment means not statistically different.
^Statistically significant difference between control and treatment means
at 0.05 level.
Statistically significant difference between control and treatment means
at 0.005 level.
^Statistical analyses not reported for difference between control and
treatment means.
1829A
6-25
03/02/84
-------
os
TABLE 6-8
Acute Toxlclty Data for Aquatic Algae Exposed to Chlorinated Benzenes
i
ivs
o
CO
ro
CO
oo
Compound Species
Monochlorobenzene freshwater algae
(Selenastrum caprlcornutural
marine algae
(Skeletonema costatum)
Green algae
(Scendesmus quadrlcauda)
l,2,-D1chlorobenzene freshwater algae
(Selenastrum capMcornutuni)
marine algae
(Skeletonema costatum)
Green algae
(Scendesmus quadrlcauda)
1 ,3-D1chlorobenzene freshwater algae
(Selenastrum caprlcornutum)
Duration
(hours)
243
483
963
96b
96C
96
243
483
96a
96b
96C
168
243
483
723
963
96b
96C
96
243
483
723
963
96°
96C
168
243
483
723
963
96b
96C
Mean
Concentration
330.0
264.0
232.0
224.0
390.0
84.8
138.0
119.0
91.6
98.0
<12.9
2.2
66.7
45.1
45.6
44.2
44.1
<12.8
>100.0
180.0
170.0
162.0
179.0
149.0
41.8
Method
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
Effect
EC50
EC50
ECSO
None
EC50
ECSO
EC50
EC50
None
EC3<1
ECso
EC50
EC50
EC50
ECSO
None
ECso
ECSO
"50
EC50
ECSO
None
EC3d
ECSO
ECSO
EC50
ECso
None
Reference
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA. 1978
U.S. EPA, 1978
CalamaH et al . ,
1983
U.S. EPA, 1978
U.S. EPA. 1978
U.S. EPA. 1978
U.S. EPA, 1978
U.S. EPA, 1978
Brlngmann and
Kuhn. 1980
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
CalamaM et al. ,
1983
U.S. EPA. 1978
U.S. EPA. 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA. 1978
U.S. EPA. 1978
Brlngmann and
Kuhn, 1980
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA. 1978
U.S. EPA. 1978
-------
« • V
TABLE 6-8 (cont.)
o
CO
r\>
CO
CO
Compound Species
l,3-D1chlorobenzene (cont.) marine algae
(Skeletonema costatura)
l,4-D1chlorobenzene freshwater algae
(Selenastrum capMcornutuia)
marine algae
(Skeletonema costatum)
1,2,3-Trlchlorobenzene freshwater algae
(Selenastrum caprlcornutum)
1,2,4-Trlchlorobenzene freshwater algae
(Selenastrum caprlcornutum)
marine algae
(Skeletonema costatum)
Duration
(hours )
243
48^
72«
963
96°
96C
243
483
723
963
96b
9&c
96
243
483
723
963
96D
96C
96
243
48a
723
963
96b
96C
96
243
483
723
963
96b
9&c
Mean
Concentration
(mg/t)
55.8
41.9
62.3
52.8
49.6
7.3
76.9
61.6
77.5
98.1
96.7
5.6
1.6
61.9
56.6
50.6
54.8
59.1
10.0
0.9
55.0
32.8
31.8
35.3
36.7
<8.2
1.4
13.5
1.46-2.63
1.46-2.63
8.75
8.93
<1.46
Method
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
Effect
"50
"50
"50
"50
"50
None
"50
"50
"50
"50
"50
None
"50
"50
"50
"50
"50
"50
None
"50
"50
"50
"50
"50
"50
None
"50
"50
"50
"50
"50
"50
None
Reference
U.S. EPA. 1978
U.S. EPA. 1978
U.S. EPA, 1978
U.S. EPA. 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA. 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA. 1978
U.S. EPA, 1978
CalamaH et al. ,
1983
U.S. EPA. 1978
U.S. EPA, 1978
U.S. EPA. 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA. 1978
CalamaM et al. ,
1983
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA. 1978
U.S. EPA. 1978
U.S. EPA. 1978
U.S. EPA, 1978
Calamarl et al. .
1983
U.S. EPA. 1978
U.S. EPA. 1978
U.S. EPA. 1978
U.S. EPA, 1978
U.S. EPA, 1978
U.S. EPA. 1978
-------
TABLE 6-8 (cont.)
03
TVJ
to
o
to
CO
CO
Compound Species
1 ,2,3,5-Tetrachlorobenzene freshwater algae
(Selenastrum caprlcornutum)
marine algae
(Skeletonema costatum)
1 ,2,4,5-Tetrachlorobenzene freshwater algae
(Selenastrum caprlcornutum)
marine algae
(Skeletonema costatum)
Pentachlorobenzene freshwater algae
(Selenastrum caprlcornutum)
marine algae
(Skeletonema costatum)
Duration
(hours)
24*
48*
72*
96*
96b
96C
24*
48*
72*
96*
96b
96C
24*
48*
72*
96*
96b
96C
24*
48*
72*
96*
96b
96C
24*
48*
72*
96*
96b
96C
24*
48*
72*
96*
96"
96C
Mean
Concentration
(mg/l)
27
.4
28.0
14
17
17
<3
2
2
1
0
0
<0
50
54
47
52
46
<3
>18
9
8
7
7
<]
>32
8
13
6
6
0
.7
.2
.7
.2
.83
.53
.39
.83
.70
.1
.4
.9
.3
.9
.8
.2
.0
.39
.56
.10
.32
.0
.0
.25
.0
.78
.63
.10
5.53
1.57
1.94
2.23
1,
<0
.98
.1
Method
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
static
Effect
"50
"50
"50
"50
"50
None
"50
"50
"50
"50
"50
None
"50
"50
"50
"50
"50
None
"50
"50
"50
"50
"50
None
"50
"50
"50
"50
"50
None
"50
"50
"50
"50
"50
None
Reference
U
U
U
U
U
U
U
U
U
U
U
U
U
U
U
U
U
U
U
U
U
U
U
U
U
U
U
.s.
.s.
.s.
.s.
.s.
.s.
.s.
.s.
.s.
.s.
.s.
.s.
.s.
.s.
.s.
.s.
.s.
.s.
.s.
.s.
.s.
.s.
.s.
.s.
.s.
.s.
.s.
U.S.
U.S.
U.S.
U.S.
U.S.
U.S.
U.S.
U.S.
U.S.
EPA.
EPA,
EPA,
EPA.
EPA.
EPA.
EPA.
EPA.
EPA.
EPA,
EPA.
EPA.
EPA,
EPA,
EPA.
EPA.
EPA,
EPA.
EPA.
EPA.
EPA.
EPA.
EPA.
EPA,
EPA.
EPA.
EPA.
EPA,
EPA,
EPA,
EPA,
EPA,
EPA,
EPA.
EPA.
EPA.
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
1978
-------
CD
no
TABLE 6-8 (cont.)
o
to
GO
oo
Compound
Hexachlorobenzene
Species
Freshwater algae
(Selenastrum capMcornutum)
Tetrahymena pyrlformls
Mixed culture; diatom/green
algae (Thalassloslra
pseudonana/Duna 1 1 e 11 a
tertlolecta)
Green algae
(Chlorella pyrenoldosa)
Duration
(hours)
96
240
72
76
Mean
Concentration Method
(mg/D
<0.03 static
0.001 static
0.1 static
10.0 static
Effect
EC50
Growth
reduction6
No growth
Inhibition
Growth
reduction^
Reference
Calamarl et al. ,
1983
Gelke and
Parasher, 1976
Biggs et al. ,
1979
Parasher et al. ,
1978
Effective on chlorophyll a content
Effective on cell growth
CNOEL
^A 3% change In growth measured by turbidity
eGrowth reduced to 66% of control cultures; measured by dry mass
fGrowth reduced to 87.5% of control cultures; measured by dry mass
= Concentration Inhibiting the growth of 50% of the population
-------
U.S. EPA (1978) also conducted similar toxldty tests on the chlorinated
benzenes with the marine algae, Skeletonema costatum. The 24, 48, 72 and
96-hour EC5Q values and the 96-hour NOELs for the chlorinated benzenes
studied are shown In Table 6-8. Effective toxldty concentrations of each
chlorinated benzene are within the same range for both the freshwater and
marine algae. Data from other studies (Brlngmann and Kuhn, 1980; Gelke and
Parasher, 1976; Biggs et al., 1979; Parasher et al., 1978) using various
algal species are also reported In Table 6-8.
6.1.5. Residues. Residue concentrations of the chlorinated benzenes (In
sediment and water) were determined 1n the Great Lakes (Superior, Huron,
Erie and Ontario), drinking water of surrounding cities, wastewater
effluents from area Industries and from the Grand and Niagara Rivers (Oliver
and Nlcol, 1982). These data, reviewed 1n Table 6-9, Indicate that almost
all chlorinated benzenes exist 1n measurable quantities 1n the Great Lakes
and can occasionally be traced to point sources. Oliver and Nlcol (1982)
Indicate that these substances are persistent 1n the sediment and are
bloconcentrated by fish.
Bjerk and Brevlk (1980) collected sediment core samples (0-5 cm deep)
and reported concentrations of 0.87 mg/kg pentachlorobenzene and 0.528 mg/kg
hexachlorobenzene (dry weight basis) In the Oslo fjord at Asstranda, Norway.
Deeper samples contained less contaminants (0.064 and 0.317 mg/kg, respec-
tively). At Ora, Norway, sediment samples contained lower levels of penta-
chlorobenzene (0.003 mg/kg dry weight). In a wide variety of species tested
(algae, crustaceans, mollusks and fish), penta- and hexachlorobenzene appear
to bloaccumulate, usually about 20-fold over environmental levels
(Table 6-10).
1829A 6-30 03/02/84
-------
TABLE 6-9
Chlorinated Benzene Concentrations (ug/i) 1n Water and Sediment3
CO
LO
Chemical
l.3-D1chlorobenzene
1 ,4-D1chlorobenzene
l,2-D1chlorobenzene
1 ,3,5-Tr1chlorobenzene
1 ,2,4-Trlchlorobenzene
7* 1,2,3-Trlchlorobenzene
CO
1 ,2,3,5-Tetrachlorobenzene
1 ,2,4,5-Tetrachlorobenzene
1 ,2,3,4-Tetrachlorobenzene
Pentachlorobenzene
Hexachlorobenzene
aSource: Oliver and N1col, 1982
o ''Highest value of four sampling
CO
Lake Lake
Superior Huron
NA
2
NA
5
NA
1
NA
0.
NA
1
NA
0.
NA
0.
NA
0.
NA
0.
NA
0.
NA
0.
sites
ND
2
4
16
ND
8
NO
2 0.7
0.2
6
ND
2 0.3
ND
1 0.4
ND
3 1
0.05
3 1
0.04
1 1
0.04
2 2
reported
Lake
Erie
NA
4
NA
9
NA
2
NA
1
NA
3
NA
0.4
NA
0.3
NA
1
NA
0.7
NA
1
NA
3
Lake
Ontario
NO
74
45
94
5
11
0.1
60
0.6
94
0.1
7
ND
6
0.1
52
0.1
33
0.2
32
0.06
97
City
Drinking
Mater
1
NA
13
NA
3
NA
ND
NA
2
NA
0.1
NA
ND
NA
0.2
NA
0.3
NA
0.04
NA
0.1
NA
Wastewater
Effluents
14
NA
660
NA
13
NA
0.3
NA
11
NA
2
NA
0.4
NA
1.2
NA
1.6
NA
0.9
NA
1.5
NA
Niagara0
River
18
94
56
8
107
3B
3
31
126
22
17
Grand
River
1
NA
10
NA
6
NA
ND
NA
2
NA
0.1
NA
ND
NA
ND
NA
0.05
NA
0.05
NA
0.06
NA
Sample
Type
W
S
W
S
W
S
U
S
W
S
W
S
M
S
M
S
W
S
W
S
W
S
NA = Not available; NO = Not dectected; S - Mean concentration 1n surfldal sediment sample; W = Mean concentration 1n water samples
-------
TABLE 6-10
oo
r-o
LD
Chlorinated Benzene Concentrations 1n a
Mean Concentration (mg/kg
CO
ro
0
w
\
0
r\j
N^
CO
-p»
Species/Tissue
Cod (Gadus morhua)
Cod, homogenate
Cod liver
Cod liver
Cod fillet
WhHIng
Sprat
Sprat oil3
Plaice
Eel
Rainbow trout
(Salmo qalrdneri )
Brown trout
(Salmo trutta)
Arctic char
(Salvellnas alpinus)
Atlantic salmon
(Salmo salar)
Number
Analyzed
7
6
6
3
3
2
4
3
3
10
6
5
6
Tri-
0.4
NA
NA
2.7
0.4
1.1
0.5
<0.01-0.5
0.2
0.3
0.6
NA
NA
NA
Tetra-
0.3
NA
NA
0.8
0.14
0.3
0.3
<0.01-0.4
0.4
0.3
1.5
NA
NA
NA
Variety of Marine Species
) of Chlorinated Benzene
Penta-
3.8
0.79
NA
12.7
1.1
4.3
4.7
0.01-3.7
0.7
0.7
3.5
NA
NA
NA
Hexa-
55.6
19.9
30.9
170
31
56
29
0.04-16
13
13
32.7
31.7
30.0
46.0
Reference
Ofstad et al., 1978
Bjerk and Brevik, 1980
Bjerk and Brevlk, 1980
Ofstad et al., 1978
Ofstad et al., 1978
Ofstad et al., 1978
Ofstad et al., 1978
Lunde and Ofstad, 1976
Ofstad et al., 1978
Ofstad et al., 1978
Oliver and N11mi, 1983
Skaftason and
Johannesson, 1982
Skaftason and
Johannesson, 1982
Skaftason and
Johannesson, 1982
-------
TABLE 6-10 (cont.)
CO
bO
Mean Concentration (mq/kq) of Chlorinated Benzene
Species/Tissue
Coho salmon
(Oncorhynchus klsutch)
Liver
Muscle
Brittle star
(Ophlura alblda)
is Hermit Crab
w (Pagurus s_p_. )
Snail
{LlttoMna IHtorea)
Sea star
(Asteroldea)
Salthe, homogenate
(Pollachlus vlrens)
Number Tr1-
Analyzed
28 NA
28 NA
15 NA
3 NA
3 NA
12 NA
13 NA
Tetra- Penta- Hexa-
NA NA 0.065°
NA NA 0.097°
NA 1.10 21.2
NA 0.88 4.3
NA NA 13.9
NA 0.78 1.03
NA 1.11 21.8
Reference
Norstrom et al., 1978
Norstrom et al., 1978
Bjerk and Brevlk, 1980
Bjerk and Brevlk, 1980
Bjerk and Brevlk, 1980
Bjerk and Brevlk, 1980
Bjerk and Brevlk, 1980
o
o
ro
CD
aValues are the concentration ranges for five sampling sites around Norway.
°Concentrat1ons expressed as wet weight of fish.
-------
Msh and Invertebrates collected from contaminated waters have been
shown to contain various levels of chlorinated benzenes. Only Ofstad et al.
(1978) collected water and sediment samples for chlorinated benzene analysis
and quantitatively confirmed the presence of tr1- through hexachlorobenzenes
In the area where contaminated fish were collected. Concentrations of
chlorinated benzenes 1n the fish were Inversely related to the distance of
the collection site from a chlorinated benzene discharge point. Data from
several reports of tissue levels of tr1-, tetra-, penta- and hexachloroben-
zene In fish from the United States, Canada and Norway are presented 1n
Table 6-10. Brunn and Manz (1982) collected 72 samples of various fish
species from several ponds, streams and rivers of Germany. Residues of
hexachlorobenzene were present 1n 66 samples (92%) at average concentrations
ranging from 0.265 mg/kg fat 1n fish from ponds without a flowing surface-
water connection to 0.463 mg/kg fat 1n fish from rivers.
Additional data on tissue levels of chlorinated benzenes In fish and
BCFs were discussed 1n Section 5.3.
6.2. EFFECTS ON NONAQUATIC ENVIRONMENTS
6.2.1. Plants. Plant seedlings and germinating seeds are commonly
exposed to 1,4-d1chlorobenzene to disrupt or arrest mitosis and facilitate
chromosome study (Meyer, 1948). Sharma and Bhattacharyya (1956) exposed
healthy root tips of 10 monocotyledons and 6 dicotyledons to a saturated
solution of 1,4-d1chlorobenzene. Chromosome fragmentation was observed In
all species after 1.5-4.5 hours of exposure. Barley, oat and wheat seed-
lings were raised 1n greenhouse pots of sand, sandy loam, clay loam or clay
treated with 1,2,4,5-tetrachlorobenzene at application rates equivalent to
0, 1.9, 5.6, 16.9, 50.6 or 151.9 kg/ha (Ameen et al., 1960). Eighteen days
after planting, a decrease was observed 1n seedling germination and 1n
1829A 6-34 03/02/84
-------
heights and root lengths of seedlings of all three varieties and 1n all four
soil types. A gradient of severity was reported, however, decreasing from
sand to sandy loam, clay loam and clay. No effects were noted 1n any
variety grown 1n any soil type treated at the highest application rate
(151.9 kg/ha) 1f planting was delayed 125 days. Mature cotton plants grown
1n Norfolk sandy loam soil were observed 30 days after soil treatment with
1,2,4,5-tetrachlorobenzene at application rates of 0-4483 kg/ha to control
nematode parasites (Adams and Rodrlquez-Kabana, 1976). There was 100%
mortality 1n plots treated at >224 kg/ha. No effects on the cotton plants
were observed at application rates of 0-112 kg/ha.
6.2.2. Insects. Pupae of the housefly, Husca v1c1na. were exposed to
"saturation concentration" vapors of each of the three dlchlorobenzene
Isomers for 3, 6 or 10 hours (Levlnson, 1955). The emergence of adult flies
8 days after exposure 1s shown 1n Table 6-11. The actual concentrations of
the various exposure atmospheres, however, were not reported.
Solutions of l,2-d1chlorobenzene 1n dlesel oil (1:3 or 1:5 ratio
d1chlorobenzene:o1l) and of an unspecified trlchlorobenzene Isomer 1n dlesel
oil (1:5 ratio) effectively eliminated all broods of the Douglas-fir beetle,
Dendroctonus pseudotsugae, when sprayed on both fallen logs and standing
trees (Gibson, 1957). The actual volumes of spray or total weight of the
chlorobenzene applied were not specified.
Fifteen virgin female wasps, Bracon hebetor. were each placed overnight
Inside glass vials, the sides of which had been uniformly coated with a 10
ppm solution of 1,3,5-tr1chlorobenzene 1n 0.25 ml of acetone (Grosch and
Hoffman, 1973). The mean llfespan of the females was shortened (15.7+1.1
days) compared with controls (22.0+0.8 days). Embryo mortality, measured by
the number of unhatched eggs, 1n the control and treated groups was similar
1829A 6-35 03/23/84
-------
TABLE 6-11
Emergence of Adult HousefHes 8 Days Following Exposure of Pupae to
"Saturation Concentration" of Dlchlorobenzene Vapors3
Emergence of HousefHes (%) Resulting from
Exposure Period of:
Chem1calb
1 ,2-D1chlorobenzene
1 ,3-D1chlorobenzene
1 ,4-D1chlorobenzene
3 hours
46±10C
15±5
2±2
6 hours
15±6
0
0
10 hours
0
0
0
aSource: Levlnson, 1955
^Percent emergence of controls = 94+2%
cln an average of 10% of the cases recorded as unhatched pupae, the flies
had died after having pushed through the pupal skin with their ptlUnum,
but with their thorax and abdomen Inside the pupal skin.
1829A 6-36 03/02/84
-------
for the first 5 days after treatment, but by the seventh day, 71% of the
eggs from treated females were unhatched.
6.2.3. Birds. The toxldty of hexachlorobenzene was tested In Gapanese
quail (Coturnlx coturnlx japonlca) by dietary administration at 0, 1, 5, 20
or 80 mg/kg diet for 90 days (Vos et al., 1971). A NOEL was reported at
1 mg/kg. At higher concentrations liver damage and porphyrln excretion In-
creased In a dose-related fashion. At 80 mg/kg 5 of 15 quail died during
the exposure period. There was a dose-related decrease 1n the hatchablllty
of eggs, especially In groups treated at 20 and 80 mg/kg (Vos et al., 1971).
Carpenter et al. (1983) also reported hepatic toxldty and porphyrla In
quail treated orally with 500 mg/kg/day hexachlorobenzene for 1, 2, 5 or 10
days. Most treatment-related changes occurred after the first dose of hexa-
chlorobenzene.
Studies on the effects of chlorinated benzenes, predominantly hexa-
chlorobenzene, on wild birds have primarily focused on the accumulation of
contaminants 1n eggs and their effects on embryo survival and reproductive
parameters. Gllbertson and Fox (1977) determined hexachlorobenzene levels
In eggs of Herring Gulls, Larus argentatus. from Lake Erie, Lake Ontario and
1n northern Alberta (used as an "uncontamlnated" control). Hexachloro-
benzene residue levels 1n eggs were 1.37, 4.30 and 0.21 mg/kg (dry matter
basis), respectively. There was a relationship between the number of
embryos that developed to pipping stages and the final percent hatching, and
the area from which they were collected. Of the eggs collected 1n
"uncontamlnated" areas (n=14), 85% developed to pipping and 69% hatched. Of
those collected at Lake Erie (n=25), 83 and 53%, respectively, pipped and
hatched. Lake Ontario-collected eggs (n=47) showed a significant (p<0.05)
decrease In survival to pipping (39%) and hatchablllty (26%). Liver weights
1829A 6-37 03/02/84
-------
and porphyrln levels 1n embryos from Lake Ontario and Lake Erie were greater
than those of the control group. Gllman et al. (1977) reported that hatch-
Ing success for Herring Gull eggs from Lakes Superior, Huron, Erie and
Ontario were 80, 72, 63 and 19%, respectively, which supports the data of
Gllbertson and Fox (1977). Additional data on residue levels of chlorinated
benzenes 1n eggs and wild birds will be discussed 1n Section 6.2.4.
6.2.4. Residues. Harp seals, Phagophllus groenlandlcus. having a high
percentage of body fat, were found to contain hexachlorobenzene residues
(Rosewell et al., 1979). Forty of 42 seal pups contained hexachlorobenzene
(concentrations unspecified), which was concluded to be transferred from
adult to fetus and also through maternal nursing of the pups.
Subcutaneous adipose tissue from wild foxes, boars and deer (1n Germany)
was analyzed for hexachlorobenzene content (Koss and Manz, 1976). The
average tissue levels (ranges) were 0.29 (0.02-0.77) mg/kg 1n 21 foxes, 0.71
(0.05-3.11) mg/kg 1n 7 wild boars and 0.03 (0.00-0.05) mg/kg In 6 female
deer. The detection of l,4-d1-, l,2,4-tr1-, 1,2,3,4-tetra-, 1,2,4,5-tetra-,
penta- and hexachlorobenzene (concentrations not reported) 1n samples of
pooled body I1p1d from Lake Ontario Herring Gulls (L. argentatus) was
reported by Hallett et al. (1982). Similarly, Szaro et al. (1979) reported
that 8 of 28 Great Black-Backed Gulls, collected 1n Maine, had average
tissue levels of 0.03 mg hexachlorobenzene/kg (wet weight). Ohlendorf et
al. (1981) reported hexachlorobenzene residues at an average concentration
of 0.23 mg/kg (wet weight) among 12 of 105 herons, Including great blue
herons, Ardea herodlas. During the period 1971-1974, Barbehenn and Relchel
(1981) examined 101 bald eagles, Hallaetus leucocephalus. and found 19
carcasses to contain an average concentration of 8.0 mg hexachlorobenzene/kg
(I1p1d basis; 2.2% body weight as I1p1d). Kaiser et al. (1980) reported
1829A 6-38 03/23/84
-------
that 23 of 168 bald eagles collected during 1975-1977 had mean carcass
levels of 0.08 mg hexachlorobenzene/kg wet weight. An Osprey, Pandlon
hallaetus (0.2 mg/kg), a great horned owl, Bubo vlrqlnlanus (0.7 mg/kg),
Swalnson's hawk (up to 5.2 mg/kg) and starlings, Sturnus vulgarls (0.21
mg/kg) also were found to contain hexachlorobenzene residues (Wlemeyer et
al., 1980; Blus et a!., 1983; Bechard, 1981; White, 1979).
Reports on the residue levels of some chlorinated benzenes In bird eggs
are summarized In Table 6-12. Hexachlorobenzene has been the most prevalent
and persistent chlorinated benzene Identified.
6.3. SUMMARY
As demonstrated In acute toxldty bloassays, the LC 1n fish gener-
ally decreases as the number of substHuent chlorine atoms on the molecule
Increases (Isomers vary). Chlorinated benzenes have adverse effects on the
reproduction of Invertebrates and fish. Monochlorobenzene tested 1n gold-
fish and largemouth bass, 1,3,5-tr1chlorobenzene tested 1n brine shrimp and
the exposure of sheepshead minnows to 1,2,4,5-tetrachlorobenzene resulted 1n
decreased hatching of eggs or embryo lethality and decreased survival of
juvenile fish.
Adverse effects of chlorinated benzenes were also apparent 1n terrestri-
al organisms. Mitosis In seeds and seedlings was disrupted by 1,4-d1chloro-
benzene; 1,2,4,5-tetrachlorobenzene affected seed germination and seedling
growth depending on soil type. Soil application rates of 224 kg/ha or
higher of 1,2,4,5-tetrachlorobenzene were found to be phytotoxlc to mature
cotton plants. Dlchlorobenzene vapors at "saturation concentrations"
Inhibited the emergence of housefly pupae, while 1,2-d1chlorobenzene and
trlchlorobenzene each 1n dlesel oil were toxic to Douglas-fir beetles.
1829A 6-39 03/02/84
-------
TABLE 6-12
Chlorinated Benzene Residues 1n Bird Eggs
CO
Compound
Tetrachlorobenzenes
Pentachlorobenzene
i
0
Hexachlorobenzene
o
CO
o
INi
Species
Herring Gull
(Larus argentatus)
Herring Gull
(Larus argentatus)
Herring Gull
(Larus argentatus)
Great Black-Backed Gull
Common tern
(Sterna hlrundo)
Double-Crested Cormorant
(Phalacrocorax aurltus)
Number
Analyzed
65
10
13
65
20
20
13
20
20
65
20
20
20
20
20
28
13
9-10
Mean
Concentration
(mg/kg)
0.026
0.015
0.024
0.039
0.024
0.025
0.025
0.022
0.021
0.451
0.315
0.09
0.115
0.115
0.12
0.03
7.67C
0.016
Location
Lake Ontario3
Lake Ontar1ob
Lake Er1eb
Lake Ontario3
Lake Ontario6
Lake Er1eb
Lake Huron0
Lake Super 1orb
Lake Michigan0
Lake Ontario3
Lake Ontar1ob
Lake Er1eb
Lake Huronb
Lake Superior0
Lake H1ch1ganb
Maine
Lake Ontario
Bay of Fundy
Reference
Hallett et al.
Hallett et al.
Hallett et al.
Hallett et al.
Hallett et al.
Hallett et al.
Hallett et al.
Hallett et al.
Hallett et al.
Hallett et al.
Hallett et al.
Hallett et al.
Hallett et al.
Hallett et al.
Hallett et al.
Szaro et al. .
Gllbertson and
1972
ZHko. 1976
. 1982
. 1982
, 1982
. 1982
. 1982
. 1982
. 1982
. 1982
, 1982
. 1982
. 1982
, 1982
. 1982
, 1982
. 1982
1979
Reynolds,
CO
-------
TABLE 6-12 (cont.)
Compound
Hexachlorobenzene
(cont.)
aOata collected 1n 1977
bData collected \n 1978
C8ased on dry weight of
Species
Canvasback Duck
(Ay thy a valUlnerla)
Red-Breasted Herganser
(Mergus serrator)
Comnon Merganser
(Mergus merganser)
Brown Pelican
(Pelecanus occidentals)
Great Horned Owl
(Bubo vlrglnlanus)
egg
Number
Analyzed
11
51
114
92
2
115
4
Mean
Concentration
(mg/kg)
0.02
0.01
0.06
0.05
0.05
0.03
0.2
Location
Nevada
Manitoba
Lake Michigan
Lake Michigan
Lake Michigan
South Carolina
Ohio
Reference
Stendell et al..
Stendell et al..
Haseltlne et al. ,
Haseltlne et al.,
Haseltlne et al..
Blus et al., 1979
Springer, 1980
1977
1977
1981
1981
1981
o
CO
o
rvj
CO
-------
Contact with residues of 1,3,5-tr1chlorobenzene shortened the Hfespan of
female wasps, and their eggs suffered high mortality within 7 days of
exposure.
Although effects (mortality, decreased reproduction) of chlorinated
benzenes on natural populations have not been adequately studied, tissue
concentrations of several Isomers were measured 1n a number of different
species. Aquatic organisms (fish and Invertebrates) and terrestrial
species, alike, have been found to contain chlorinated benzenes. Tissue
concentrations of the quantltated chlorinated benzenes were highest for
hexachlorobenzene. The detection 1n North America and Europe of hexachloro-
benzene 1n the eggs of birds and subcutaneous fat of wild animals suggests
Its widespread distribution 1n the environment.
1829A 6-42 03/23/84
-------
7. MONOCHLOROBENZENE
Between 88.7 and 128.7 million kilograms of monochlorobenzene 1s
estimated to be produced 1n the United States 1n 1983 (U.S. EPA, 1983).
Monochlorobenzene 1s used primarily as an Intermediate 1n the synthesis of
organic chemicals and as a solvent 1n herbicides and paints (Hawley, 1977).
It has been detected 1n samples of urban, ambient and Indoor air, as well as
1n surface, drinking and Industrial wastewater, and 1n water and sediments
1n a stream draining an abandoned waste site (see Section 4.3.). Residues
of monochlorobenzene have been found 1n human adipose tissue, and studies
indicate that 1t bioaccumulates in fish and other aquatic organisms (see
Sections 5.3. and 5.4.). In addition to the exposure of workers Involved in
organic chemical synthesis, humans are likely to be exposed to monochloro-
benzene via Inhalation of air and 1ngest1on of water.
7.1. PHARMACOKINETICS
7.1.1. Absorption. Quantitative studies on the absorption of monochloro-
benzene are lacking. Toxic effects reported in humans after 1ngest1on or
Inhalation Indicate that monochlorobenzene 1s absorbed via these routes
(Reich, 1934; Rosenbaum et al., 1947; Tarkhova, 1965). Studies of the
metabolism of monochlorobenzene In a number of mammalian species indicate
that absorption from the gastrointestinal tract does occur (Williams, 1959).
Given the Upophllic character of monochlorobenzene and the dermal absorp-
tion of other chlorobenzenes, some degree of absorption through the skin
would be expected.
7.1.2. Distribution. The only available study regarding the distribution
of monochlorobenzene is the inhalation pharmacokinetic experiments of
Sullivan et al. (1983). Male Sprague-Dawley rats were exposed to 100, 400
or 700 ppm of 14C-monochlorobenzenene, 8 hours/day for 1 or 5 consecutive
1830A 7-1 03/27/84
-------
days. Following a single exposure period, radioactivity was found 1n all
tissues examined both Immediately and 48 hours post-exposure, with the
highest concentrations located 1n the fat. With the exception of the
kidney, five exposures did not result 1n significantly higher tissue con-
centrations than did a single exposure, Indicating that a steady-state
concentration 1s reached during the first 8 hours of exposure. The tissue
concentration was proportional to the exposure concentration, with the
exception of the fat, 1n which the tissue levels Increased 8- to 10-fold
when the exposure concentration was Increased from 100-400 ppm and 3- to
5-fold when the exposure concentration was Increased from 400-700 ppm.
7.1.3. Metabolism. Shlmada (1981) administered monochlorobenzene to rats
(strain and dose unspecified) by subcutaneous Injection and analyzed the
urine by high performance liquid chromatography. They detected p_-chloro-
phenylmercaptudc add and monoglucuronlde and ethereal sulfate conjugates
of 4-chlorocatechol. Based on this Information, they proposed that the
metabolism of monochlorobenzene Involves an Initial oxidation to form
4-chlorobenzene-l,2-epox1de. This Intermediate may then 1) form a gluta-
thlone conjugate, resulting 1n the excretion of £-chlorophenylmercaptur1c
add, 2) be converted to 4-chlorophenol, conjugated, and excreted, or 3) be
converted to 4-chlorocatechol, conjugated, and excreted.
Nakajlma and Sato (1979) found that fasting enhanced the activity of
liver enzymes for monochlorobenzene 1n both male and female Wlstar rats.
They found that fed male rats metabolized most of the hydrocarbons tested
more rapidly than fed female rats; however, there were no significant
differences 1n the Initial metabolic rate for monchlorobenzene between sexes.
Selander et al. (1975) Investigated the metabolism of monochlorobenzene
1n perfused rat livers and 1n a variety of cell-free hepatic preparations
1830A 7-2 03/17/84
-------
(Table 7-1). They found that monochlorobenzene 1s converted to chloro-
phenols by three different enzymes. Two of these enzymes form arene oxide
Intermediates (3- and 4-chlorobenzene oxides) resulting 1n the formation of
o- and p_-chlorophenol. m-Chlorophenol appeared to occur via a direct oxlda-
tlve pathway. Under the conditions of these assays, conjugation of the
arene oxide with glutathlone or hydratlon did not occur to a significant
extent.
Smith et al. (1972) administered 75 yd (0.59 gm) of 14C-monochloro-
benzene emulsified 1n Cremophor E.L. and physiological saline to two -1.5 kg
female Dutch rabbits by gavage, twice a day for 4 days. The major urinary
metabolites recovered were p_-chlorophenylmercaptur1c add and the conjugates
of 4-chlorocatechol. Other minor metabolites detected were qulnol, 3-chlo-
rocatechol, o-chlorophenylmercaptudc add and m-chlorophenylmercaptur1c
add. The Identified metabolites accounted for over 98% of the urinary
radioactivity and consisted of 3,4-d1hydro-3,4-d1hydroxychlorobenzene
(0.57%), monophenols (2.84%), dlphenols (4.17%), mercapturlc adds (23.80%),
ethereal sulfates (33.88%) and glucuronldes (33.57%).
7.1.3.1. TISSUE BINDING -- Reid (1973) and Reid et al. (1973) have
studied tissue distribution and tissue binding of monochlorobenzene and the
related halobenzene, bromobenzene. Treatment of C57B6J mice with a single
1ntraper1toneal dose of 4.58 mmol/kg bromobenzene or 6.75 mmol/kg monochlo-
robenzene produced necrosis of the proximal convoluted tubules of the
kidneys within 48 hours. This was associated with covalent binding of an
unidentified 14C labeled metabolite to the site of necrosis prior to
manifestation of the hlstologlc effect. Pretreatment of animals with
pyrazole butoxlde blocked the binding as well as the toxic effect. Six
hours after administration of 1 mmol/kg (112 mg/kg), -0.332 nmol equiva-
lents of 14C-monochlorobenzene/mg protein were covalently bound. Although
1830A 7-3 03/17/84
-------
TABLE 7-1
Percentage of Isomers of Chlorophenol from
Metabolism of Monochlorobenzene*
System
Perfused liver
Phenobarbltal treated
Methylcholanthrene treated
Mlcrosomes
Phenobarbltal treated
Methylcholanthrene treated
ortho-
40
46
89
18
32
59
Isomer (X)
meta-
20
10
2
7
6
6
para-
40
44
9
75
62
35
*Source: Selander et al., 1975
1830A 7-4 03/17/84
-------
tissue distribution was not studied with monochlorobenzene, a metabolite of
bromobenzene was strongly bound by tissues from the liver, lungs and kidneys
but not by tissue from the heart, spleen or testes, and this binding corre-
lated with necrotlc changes. Mlcrosomes from the lungs and liver (in vitro)
oxidized bromobenzene, whereas mlcrosomes from the kidneys, heart, spleen
and testes did not, which Indicated that metabolic activation took place 1n
lungs and liver and that an active metabolite was transported to the kidneys
before binding. Pretreatment with 3-methylcholanthrene enhances the overall
metabolism of monochlorobenzene; however, this pretreatment reduces the
extent of covalent binding to cellular macromolecules and prevents centro-
lobular hepatic necrosis (Reid et al., 1971). Similar results of preventing
chlorobenzene-el1c1ted liver necrosis have been obtained by Inhibiting
epoxlde hydrase with cyclohexene oxide (Oesch et al., 1973). Jergll et al.
(1982) found that when monochlorobenzene was Incubated with liver mlcrosomes
H was bound to mlcrosomal proteins of molecular weights of 72,000 and
50,000-60,000 daltons. The metabolite probably was bound to the sulfhydryl
groups of proteins, since the addition of glutathlone blocked the binding.
7.1.4. Excretion. Sullivan et al. (1983) exposed male Sprague-Dawley
rats to atmospheres containing 14C-monochlorobenzene (100, 400 or 700 ppm)
8 hours/day for 1 or 5 days. Following treatment, the label was detected 1n
the expired air and urine of the rats. The urine contained metabolites of
monochlorbenzene, Including mercapturlc acids, glucuronlde conjugates and
sulfate conjugate; the respiratory elimination consisted of unmetabollzed
compound. The percentage of the dose excreted by respiration Increased with
Increasing exposure, Implying that the metabolic elimination of monochloro-
benzene can be saturated.
1830A 7-5 03/27/84
-------
Smith et al. (1972) orally dosed two female Dutch rabbits with 0.5 g (75
yC1) of 14C-monochlorobenzene emulsified 1n Cremophor E.L. and physio-
logical saline twice a day for 4 days, and collected urine and feces
throughout the 7 days of the study. The urine contained 19.6% of the admin-
istered label, the feces (methanol extracted) contained 1.05% and the
tissues contained 0.05%. Radlolabeled 14C 1n expired air was not mea-
sured. Williams (1959) has reported that 27% of a 0.5 g/kg dose orally
administered to rabbits was excreted 1n expired air over a 1-2 day period.
Lindsay-Smith et al. (1972) found that the conjugated metabolites were
both mono- and diphenollc 1n the rabbit, but the monophenollcs were predom-
inate. p_-Monochlorophenol was the predominant Isomer 1n the urine. The
distribution of Isomers for free and conjugated monochlorophenol combined
was: ortho-, 4.9%; meta-, 22.9%; and para-, 72.2%. For free monochloro-
phenols, the distribution of Isomers was 5.9, 33.6 and 60.4% for ortho-,
meta- and para-1somers, respectively. The major diphenollc metabolite was
reported to be 4-chlorocatechol; small amounts of chloroqulnol, 3-chloro-
catechol and qulnol also were found. Although there was not adequate proof
1n these studies, 1t was proposed that metabolism proceed through the forma-
tion of an arene oxide (3,4-chlorobenzene oxide). Conjugation of this arene
oxide with glutathlone followed by further metabolic reactions would account
for the meta- and para-chlorophenyl mercapturlc adds but not the ortho-
Isomer. Hydratlon of the arene oxide, followed by dehydrogenatlon, would
lead to chlorocatechol. Pathways for metabolism have been proposed based on
the In vivo and Ijn vitro studies (Figure 7-1).
The profile of urinary metabolites varies from species to species. For
example, Williams et al. (1975) reported on 13 species and Indicated that
19-65% of l4C-ur1nary metabolites of monochlorobenzene was p_-chloro-
1830A 7-6 03/23/84
-------
Cl
Cl
Cl
H
S-glutathione
OH
3-chlorophenol
conjugation
'oercapturic acid
glucuronide
sulfste
4-chlorophenol
conjugation
(""glucuronidej
[sulfate J
I dehydrogenise
Cl
OE
di
A-chlorocatechol
SCH 2CHCOOH
NHCOCH.
4-chlorophenylniercapturic acid
FIGURE 7-1
Metabolism of Monochlorobenzene
Adapted from: Williams, 1959; Lindsay-Smith et al.f 1972;
Selander et al., 1975; Shlmada, 1981; Sullivan, 1981
1830A
7-7
03/23/84
-------
phenyl mercaptuMc add. The metabolites 1n humans were the same as those
1n animals, but the proportions of metabolites were different (Table 7-2).
In humans, 19% appeared as the mercapturlc add and 33 and 31X, respec-
tively, were excreted as 4-chlorophenol and 4-chlorocatechol sulfate, and
glucuronlde conjugates. The ultimate urinary metabolites would also be
expected to vary depending on saturation of metabolism or on the nutritional
state of the animals. If glutathlone levels are depleted, the metabolic
fate can vary. Sullivan (1981) found that monochlorobenzene metabolism was
saturable 1n rats. Male Sprague-Dawley rats were exposed via Inhalation to
100, 400 or 700 ppm monochlorobenzene vapor for an 8-hour period. Urinary
metabolite profiles and tissue glutathlone concentrations were measured at
16 and 48 hours after exposure. The capacity of metabolic oxldases and the
conjugation of metabolites to glutathlone were saturated at the two higher
levels of exposure. Saturation of detoxification mechanisms can Increase
the Incidence and severity of toxldty. Recent studies have examined the
profile of urinary metabolites after Inhalation exposure (Sullivan, 1981) or
after subcutaneous administration (Shlmada, 1981). Essentially, the results
of these studies are consistent with results 1n other spedes that were
administered monochlorobenzene orally.
Ogata and Shlmada (1982) compared the metabolism of monochlorobenzene 1n
rats and humans. The compound was diluted with polyethylene glycol and
Injected 1ntraper1toneally Into rats or administered to rats and human
volunteers orally. Urine specimens were also collected from two workers at
a factory Involved 1n distilling raonochlorobenzene. In rats, the major
metabolite detected was p_-chlorophenylmercaptur1c add, accounting for 6-10
times the amount of material excreted as conjugates of 4-chlorocatechol.
In a human volunteer, only trace amounts of j)-chlorophenylmercaptur1c
1830A 7-8 03/27/84
-------
TABLE 7-2
Species Variation 1n Urinary Metabolites of ^C-Monochlorobenzene*
Species
Man
Rhesus monkey
Squirrel monkey
Capuchin monkey
Dog
Ferret
Hedgehog
Rabbit
Rat
Mouse
Gerbll
Hamster
Guinea pig
Percentage
4-Chlorophenol
33
19
14
19
14
33
20
29
23
20
13
15
27
of 24-Hour Excretion
4-Chlorocatechol
31
37
37
36
45
31
12
38
22
31
26
23
35
of 14C
4-Chlorophenyl-
Mercapturlc Add
19
40
50
41
42
24
65
26
49
42
51
43
21
*Source: Data cited by Williams et al.. 1975
1830A
7-9
03/27/84
-------
add were detected; however, conjugates of 4-chlorophenylmercaptur1c add
were the major metabolites observed. These findings suggest that urinary
4-chlorocatechol conjugates may be used to monitor human exposure to
monochlorobenzene.
7.1.5. Summary. Monochlorobenzene 1s readily absorbed by Inhalation and
by the gastrointestinal tract but the quantitative extent 1s not known. It
1s deposited 1n body I1p1ds and metabolized by mlcrosomal oxidation. Oxlda-
tlve reactions lead to the formation of arene oxides; these epoxldes are
metabolized further to the ortho-, meta- or para-chlorophenols. The chloro-
phenols may conjugate with glutathlone and be detoxified by conversion to
the corresponding mercaptuMc adds and excreted In the urine or they may
bind to cellular proteins. Binding to cellular protein appears to be
correlated with necrotlc pathologic changes 1n the kidneys and livers of
rodents. In addition to conjugation with glutathlone, metabolites of mono-
chlorobenzene (monophenols and dlphenols) can conjugate with glucuronlc add
or with sulfate and be excreted 1n the urine. Monophenols are the predomi-
nant metabolites; the dlphenols are minor. The arene oxides, 3-chloroben-
zene oxide or 4-chlorobenzene oxide, also can be converted to the dlhydro-
dlol by epoxlde hydrase and dehydrogenated to form chlorocatechols. There
appear to be species differences 1n the profile of urinary conjugation of
metabolites, and end metabolites may vary depending on the availability of
tissue glutathlone. Detoxification by conjugation with glutathlone 1s
Important 1n the modulation of toxic effects especially at high exposure
levels.
7.2. EFFECTS ON HUMANS
No ep1dem1olog1c studies regarding the effects of exposure to monochlo-
robenzene are available. Several case studies and one clinical study,
1830A 7-10 03/17/84
-------
however, provide some Information regarding the toxic effects of the chem-
ical 1n humans. Maximum allowable air concentrations range from 75 ppm In
the United States and Switzerland to 11 ppm 1n Sweden (Merlan, 1980).
Reich (1934) reported the case of a 2-year-old boy who swallowed -5-10
ml of monochlorobenzene. WHhln 2 hours, the child's lips were cyanotlc,
and he had no detectable reflexes. He became unconscious and cyanotlc and
displayed head and neck twitching. He regained consciousness after ~3 hours
and all signs returned to normal within 8 hours. There was no followup on
the patient.
Glrard et al. (1969) reported the case of a 70-year-old woman who had
worked for 6 years with a glue containing 70% monochlorobenzene. From the
time when she began using the glue, her symptoms Included headaches and
Irritation of the upper respiratory tract and the eye mucosa. After 6 years
of exposure hematologlc examination resulted 1n a diagnosis of medullar
aplasla.
Rosenbaum et al. (1947) examined 28 factory workers who had been exposed
to monochlorobenzene for 1-2 years. Many of the workers complained of head-
aches and showed signs of somnolescence and dyspepsia. Eight of the 28 had
tingling, numbness and stiffness of the extremities, eight had hyperesthesla
of the hands, nine had spastic contractions of the finger muscles, and two
had spastic contractions of the gastronemlus muscle. Twenty-six workers who
had either short-term exposure (<1 year) to monochlorobenzene or exposure to
combinations of benzene and monochlorobenzene fumes displayed no neurotoxlc
signs.
Tarkhova (1965) exposed 4 humans to 0.02, 0.04 or 0.06 ppm (0.1, 0.2 or
0.3 mg/m3) of monochlorobenzene and monitored electroencephalographlc
patterns. At the lowest concentration there were no effects, but within
1830A 7-11 03/17/84
-------
minutes at the higher doses, there were changes 1n response patterns to
10-nanosecond light flashes of 8-10 Hz.
Human exposure to monochlorobenzene by Inhalation or by accidental
1ngest1on can cause neurotoxlc signs (Reich, 1934; Rosenbaum, 1947). It 1s
not known 1f the effects are reversible after long-term exposure or 1f there
are other sites of toxldty.
7.3. MAMMALIAN TOXICITY
7.3.1. Acute ToxIcUy. Treatment with monochlorobenzene has been demon-
strated to produce a variety of changes 1n enzymatic and physiological func-
tion, Including the slight depression of mitochondrlal oxldatlve
phosphorylatlon 1n male Oonryu rats (Ogata et al., 1981), Increased flow of
bile duct-pancreatic fluid 1n male Holtzman rats (Yang et al., 1979),
stimulating the activity of 6-am1nolevul1n1c add synthetase and
hemeoxldase 1n male Wlstar rats (Ar1yosh1 et al., 1981) and decreasing
hepatic cytochrome P-450 1n female Wlstar rats (Ar1yosh1 et al., 1975).
Varshavskaya (1967) Investigated the toxlcologlcal, olfactory and gusta-
tory properties of monochlorobenzene and ortho- and para-dlchlorobenzene.
The olfactory and gustatory thresholds were found to be 0.01-0.02 mg/9. for
monochlorobenzene. In the oral toxldty tests with albino rats, the highest
concentration of monochlorobenzene that produced no observed toxic effect
was 0.001 mg/kg.
R1m1ngton and Zlegler (1963) administered monochlorobenzene to male
albino rats by dally gastric Intubation, using an escalating dosage regimen.
*
Monochlorobenzene was less effective 1n producing porphyMa than were
1,4-d1chlorobenzene, 1,2,4-tMchlorobenzene or 1,2,3,4-tetrachlorobenzene
(hexachlorobenzene was not studied). Monochlorobenzene also has been
observed to produce bronchlolar necrosis (Reid et al., 1973) and centro-
lobular hepatic necrosis (Reid and Krishna, 1973).
1830A 7-12 03/17/84
-------
A summary of the acute lethal doses of monochlorobenzene 1s presented 1n
Table 7-3. In a majority of the studies reviewed, fatalities were the
result of central nervous system depression. Irish (1963) reported that
cats tolerated monochlorobenzene at concentrations of 220-660 ppm for 1
hour. Narcotic signs were noted at levels of 1200 ppm, and death occurred
after 7 hours of exposure at 3700 ppm. Cats exposed at 8000 ppm for 30
minutes died 2 hours after exposure. By the oral route, LD™ values 1n
rats and rabbits were reported to be 2.91 and 2.83 g/kg bw, respectively.
Bonnet et al. (1982) reported that 6-hour Inhalation exposures to rats and
mice resulted 1n LCcns of 2965 and 1886 ppm, respectively.
bu
Administration of sublethal doses of monochlorobenzene causes toxic
signs that are manifest within 24 hours. When mice are given a single
1ntraper1toneal dose of 6.75 mmol/kg (760 mg/kg), they develop coagulation
necrosis of the proximal tubules of the kidneys. Rats are slightly less
sensitive. Doses of 9.3 mmol/kg (1047 mg/kg) have been reported to cause
swollen, vacuolated, convoluted tubules (Reid et al., 1971).
Monochlorobenzene causes sensory Irritation of the respiratory system.
A comparison of the Index of sensory Irritation for 22 chemicals was made
based on a short Inhalation experiment 1n mice (De CeaurMz et al., 1981).
Mice were exposed usually for 5 minutes at varying concentrations, and
respiratory rates were measured with a plethysmograph. An RD value for
mice, which 1s the concentration that causes a 50% decrease 1n respiratory
rate, was calculated. An uncomfortable human dose was predicted to be 0.1
RD , and a no-effect dose was predicted to be 0.01 RD,-n- For monochlo-
robenzene, the RDrQ was 1054 ppm, and the predicted no-effect human dose
was 11 ppm. For comparison, the RD™ for formaldehyde and toluene d11so-
cyanate were 5.3 and 0.24 ppm, respectively.
1830A 7-13 03/27/84
-------
TABLE 7-3
CD
CO
O
3>
Species
Rat
Cat
^ Rat»
Tj Sprague-Dawley
Mouse
Rat
Rat
Rabbit
Rat
Guinea pig
RabbH
o
" *95% confidence 1
ro
en NR = Not reported
Acute
Route
Inhalation 22,000
9,000
Inhalation 3,700
8,000
Inhalation 2,965
Inhalation 1,886
oral 2,144
Toxldty of Monochlorobenzene
Dose
ppm
ppm
ppm
ppm
(2787-3169)* mg/kg
(1781-1980)* mg/kg
mg/kg
oral 400-1600 mg/kg
oral 2,830
1.p. 7,400
1.p. 4,100
dermal >10
1m1ts 1n parentheses
mg/kg
mg/kg
mg/kg
g/kg
Exposure
Duration
(hour)
2.5
3.0
7.0
0.5
6.0
6.0
NR
NR
NR
NR
NR
NR
Lethal
Effect
Level
LC50
LC100
LC100
LC50
LC50
LD50
LD50
LD50
LD50
LD50
LD50
Reference
Eastman Kodak,
Irish, 1963
Bonnet et al. ,
Bonnet et al. ,
Monsanto, 1965
Eastman Kodak,
Eastman Kodak,
NIOSH, 1982
NIOSH, 1982
Monsanto, 1965
1978
1982
1982
1978
1978
-------
Biochemical manifestations of the acute toxic effects of monochloroben-
zene may be associated with the binding of liver and kidney protein by
metabolites of the compound (the arene oxide or monochlorophenol) as dis-
cussed 1n Section 7.1.2. Ogata et al. (1981) found that 0.24 mM monochloro-
benzene, 1n an in vitro assay, caused a slight depression of rat liver mlto-
chondrlal oxldatlve phosphorylatlon. This effect was much less than the
effect caused by more highly chlorinated congeners and may be correlated
with a slight decrease 1n cytochrome P-450 1n the liver of rats administered
200 mg/kg monochlorobenzene 1ntraper1toneally 24 hours before analysis
(AMyoshl et al., 1975).
7.3.2. Subchronlc ToxUUy. The subchronlc toxldty data are summarized
1n Table 7-4. Several Investigators have studied the subchronlc Inhalation
toxldty of monochlorobenzene. Dllley (1977) exposed groups of 32 male
Sprague-Oawley rats (125 g) or male rabbits (2.0-2.5 kg) to monochloroben-
zene (99+%) at 0, 75 and 250 ppm for 7 hours/day, 5 days/week, for 24 weeks.
After exposure for 11 weeks (55 exposures), the rats showed Increased Hver-
to-body weight ratios. After 120 exposures at 250 ppm, the rats showed an
Increase 1n I1ver-to-body and kidney-to-body weight ratios as well as
decreased food consumption. Slight changes were also observed In three
hematologlc parameters (retlculocyte, white blood cell, and platelet
counts). H1stopatholog1c changes were seen 1n the kidneys, liver and
adrenals of rats at 11 and 24 weeks; the kidneys had regenerating cortical
tubules with basophlllc Inclusions 1n the cytoplasm of cells, the livers
were congested and the adrenals had vacuolatlon of cells 1n the zona fascl-
culata. It was suggested that 75 ppm may be the marginal toxic concentra-
tion for dally Inhalation. Effects were less marked In rabbits than In
rats; no hlstologlc or hematologlc changes were found relating to monochlo-
robenzene exposures at 24 weeks.
1830A 7-15 03/27/84
-------
TABLE 7-4
03
CO
o
J>
Species Route
Dog Inhalation0
(beagle)
— j
i
^ Rat Inhalation
Rat Inhalation
Rat Inhalation
Rat Inhalation
Rat Inhalation
Rat Inhalation
o
CO
J^ Rabbit Inhalation
10
\
no
-f*
Summary of Subchronlc Toxldty Studies on Monochlorobenzenea
Dose
0.75 mg/l, 6 hrs/day.
5 days/week (162 ppra)
1 .50 mg/l, 6 hrs/day.
5 days/week (424 ppm)
2.00 mg/l, 6 hrs/day,
5 days/week
0.75, 1.50 or 2 mg/l
6 hrs/day, 5 days/week
0.1 or 1.0 mg/m3
(continuous)
0.1 mg/m3 (continuous)
1.0 mg/m3 (continuous)
0.1. 1.25 or 1.5 mg/l
0.1 mg/l, 3 hr/day
(alternate days)
75 and 250 ppm, 7 hrs/day
5 days/week
75 and 250 ppm, 7 hrs/day,
5 days/week
Duration
(days)
62
exposures
over 90 days
62
exposures
over 90 days
62
exposures
over 90 days
62
exposures
over 90 days
72-80
60
60
49-98
37 weeks
120
exposures
120
exposures
Effects Reference
None Monsanto, 1978
Weight loss; conjunctivitis; moribund at
31 days
Weight loss; hypoactlvlty and conjunctivitis;
vacuolated nepatocytes; cytoplasmlc vacuolatlon
of renal collecting tubules; bilateral atrophy
of seminiferous tubules; lower total leukocyte
counts, elevated SAP, SCOT, SGPT; aplastlc bone
marrow; mortality 1n 5/8 dogs after 25-29 days
None Monsanto, 1978
Liver necrosis and regeneration; kidney Khanln, 1977
hyperplasla; encephalopathy; pneumonia
None Tarkhova, 1965
Inhibited chronaxla of antagonistic muscles
at 39 days; Increased blood chollnesterase
Chronax1metr1c Inhibition Plslaru, 1960
Inhibition of extensor t1b1al1s 7-14 weeks; Gabor and Raucher,
normal by 20 weeks 1960
Focal lesions of adrenal cortex; lesions 1n DUley, 1977
tubules of kidneys; congestion of liver and
kidneys; decreased SGOT
Decreased SGOT after 24 weeks of exposure 011 ley, 1977
-------
I « t
TABLE 7-4 (cont.)
as
Species
Route
Dose
Duration
(days)
Effects
Reference
Mouse oral (gavage) 60 mg/kg/day, 5 days/week 13 weeks
125 rag/kg/day, 5 days/week 13 weeks
250 mg/kg/day, 5 days/week 13 weeks
500 rag/kg day. 5 days/week 13 weeks
750 mg/kg/day, 5 days/week 10 weeks
Rat Oral (gavage) 60 mg/kg/day, 5 days/week 13 weeks
125 mg/kg/day, 5 days/week 13 weeks
250 mg/kg/day. 5 days/week 13 weeks
500 mg/kg/day, 5 days/week 13 weeks
750 mg/kg day, 5 days/week
13 weeks
CO
CO
one male with hepatic necrosis NTP, 1983
Increased liver weights In males one male
with hepatic necrosis
>50X reduction 1n weight gain, Increased
excretion of coproporphyrlns 1n females,
Increased liver weights, lesions of the
liver, kidney, bone marrow, spleen and
thymus
100X lethal to males within 1 week,
reduced body weight gains, polyurla
In females. Increased liver weights,
lesions of the liver, kidney, bone
marrow, spleen and thymus.
100% lethal to male mice within 1 week
and to female mice within 10 weeks.
lesions of the liver, kidney, bone marrow.
spleen and thymus at death
None NTP. 1983
None
Minimal centrolobular hepatocellular
necrosis
Decreased body weights gain. Increased
GGTP and alkaline phosphatase 1n females.
Increased excretion of porphyrlns, con-
trolobular hepatocellular necrosis,
nephropathy In males, myelold depletion
of bone marrow.
Decreased body weight gain and survival
of animals, hematologlc effects, Increased
GGTP and alkaline phosphatase In females.
polyurla 1n males. Increased excretion of
porphyrlns, centrolobular hepatocellular
necrosis, nephropathy, lymphold depletion
of thymus and spleen, myelold depletion of
bone marrow.
-------
TABLE 7-4 (cont.)
Species Route Dose
Dog oral (capsule) 27.3 mg/kg/day
54.6 mg/kg/day
272.5 mg/kg/day
•^j
i
o^ Rat oral (diet) 12.5 or 50 mg/kg/day
100 mg/kg/day
250 mg/kg/day
Rat oral (diet) 14.4 mg/kg/day
144 and 288 mg/kg/day
aSource: Updated from U.S. EPA, 1980a
bl ppm -4.60 mg/m», 1 mg/l -219 ppm (Irish, 1963)
0
CO
Duration
(days)
90
90
90
93-99
93-99
93-99
192
192
Effects
None
Diarrhea and vomiting; conjunctivitis
4/8 died 1n 3-5 weeks; Increased Immature
leukocytes; elevated SGOT and SAP, b1l1rub1n
and cholesterol; low blood sugar; hlstopatho-
loglc changes In liver, kidneys, spleen
None
Increased liver and kidney weights
Increased liver and kidney weights;
retarded growth In males
None
Increased liver and kidney weights;
Increased salivation and hair loss
Reference
Monsanto, 1967a
Monsanto, 1967b
Irish. 1963
oo
-------
Monsanto (1978b) exposed by Inhalation Charles River albino rats to
monochlorobenzene at 0, 0.76, 1.47 and 2.00 mg/8. (0, 165, 319 and 434
ppm), 6 hours/day, 5 days/week for 62 exposures. Fifteen rats of each sex
were exposed at each dose level. Erythema and hair loss were noted 1n 2 of
30 animals at the lowest dose. Hematology, clinical chemistry values and
urlnalysls parameters were found to be similar between the treated and
control groups, and no hlstopathologlc changes attributable to monochloro-
benzene were found.
Beagle dogs exposed under the same regimen as the rats had toxic mani-
festations. Although no effects were noted at 0.75 mg/l, at 1.5 mg/l, 2
of 8 dogs were moribund and sacrificed at 30 days; they were hypoactlve, had
decreased weight gain, and conjunctivitis. No clinical or hlstopathologlc
examination was made on this group. At the 2.0 mg/a level, all the dogs
displayed weight loss, hypoactlvlty, and conjunctivitis. The mean leukocyte
counts of these dogs were lower than 1n controls at 45 and 90 days, and SAP
and SGOT were elevated at 38 days. Five dogs were moribund and therefore
sacrificed between days 25 and 38. Hlstopathologlc examination revealed
vacuollzatlon of hepatocytes 1n 5 of 8 dogs, aplastlc bone marrow In 5 of 8
dogs, abnormalities of collecting tubules of the kidneys 1n 4 of 8 dogs, and
bilateral atrophy of seminiferous tubules 1n 2 of 4 dogs.
Tarkhova (1965) exposed by Inhalation adult male rats to monochloroben-
zene at 0.1 or 1.0 mg/m3 (0.02 or 0.2 ppm) for 60 days of continual
exposure. No effects were seen at the lower level, but neurotoxlc effects
were noted at the higher level. In the high dose group, the chronaxy ratio
of antagonistic muscles was reversed at day 39 (I.e., the conduction speeds
of nerve Impulses to sets of flexor and extensor muscles had changed). Blood
1830A 7-19 03/27/84
-------
chollnesterase was Increased before the chronaxlmetrlc changes developed.
Similar neurotoxlc effects 1n rats were reported by Plslaru (1960) and Gabor
and Raucher (1960).
Subchronlc toxldty studies regarding the effects of monochlorobenzene
administered to rats and dogs via gavage (oral administration) have been
reported by Monsanto (1967a,b). Male and female rats (18 of each sex 1n
each group) were dosed with 0, 12.5, 50, 100 or 250 mg/kg monochlorobenzene
1n corn oil for 5 days/week for 13 weeks. There were no effects on mortal-
ity, no clinical signs of abnormality and no hlstopathologlc lesions. A
slight decrease 1n growth rate over controls 1n males receiving the highest
dose level and a dose-related Increase 1n salivation 1n the animals were
noted.
Groups of 4 male and 4 female beagle dogs were given repeated doses of
27.3, 54.6 and 272.5 mg/kg of monochlorobenzene by capsule for 5 days/week
for 13 weeks. At the highest dose, two animals died and two were moribund
and sacrificed 1n the Interval between 14 and 21 doses. All animals given
doses of 272.5 mg/kg had weight' loss and hlstologlc changes 1n the liver,
kidneys, gastrointestinal mucosa and hematopoletic tissues. Minimal hlsto-
loglc changes were seen at 54.6 mg/kg, and no effects were noted at the
lowest dose. Animals that survived the higher dose had Increases 1n SGPT,
SAP, b1!1rub1n and cholesterol.
Subchronlc toxldty studies on monochlorobenzene were conducted under
the auspices of the National Toxicology Program (NTP, 1983b). The Investi-
gations were completed using 10 male and 10 female B6C3F mice and using
10 male and 10 female F344/N rats. The monochlorobenzene was administered
by gavage using a corn oil vehicle, 5 ml/kg bw, 5 days/week for 13 weeks.
The monochlorobenzene doses used were 0, 60, 125, 250, 500 and 750 mg/kg bw.
1830A 7-20 03/17/84
-------
The mouse study resulted 1n 13-week survival rate of 100% (10/10), 100%
(10/10), 100% (10/10), 44% (4/9), 0% (0/10) and 0% (0/10) 1n male mice and
90% (9/10), 100% (10/10), 100% (10/10), 60% (6/10), 30% (3/10) and 0% (0/10)
in female mice for the 0, 60, 125, 250, 500 and 750 mg/kg dose groups,
respectively (NTP, 1983b). Body weight gains during the 13 weeks were
decreased when compared with control animals In the surviving male mice, 27%
for the 60 and 125 mg/kg groups, and 82% for the 250 mg/kg group. A
decrease 1n body weight gains 1n surviving female mice was seen only 1n the
250 and 500 mg/kg dose groups (50% decrease 1n both groups). No clear
compound-related effects were found 1n the surviving monochlorobenzene-
treated mice from the hematologlc and clinical analyses performed. Polyurla
was noted 1n the 750 mg/kg male group and the 500 mg/kg female group.
Significantly Increased excretion of coproporphyrlns were observed 1n sur-
viving female mice receiving 250 and 500 mg/kg. No changes 1n liver
porphyrln concentrations were observed In any of the male or female mice.
At sacrifice Increased liver weights were observed In surviving male mice at
125 and 250 mg/kg and surviving female mice at 250 and 500 mg/kg. Dose
dependent monochlorobenzene-lnduced Injury was revealed after histologic
examination of liver, kidney, bone marrow, spleen and thymus. Except for
two male mice each with hepatic necrosis 1n the 60 and 125 mg/kg dose
groups, the observed tissue Injuries, which were graded as severe, only
occurred 1n the 250, 500 and 750 mg/kg dose groups. The liver lesions
consisted of focal hepatocytlc necrosis and centrllobular hepatocyte degen-
eration at 250 mg/kg and centrllobular hepatocellular necrosis at 500 and
750 mg/kg dose levels. Nephropathy was observed 1n female mice at 250 mg/kg
dose, and 1n male mice at 250, 500 and 750 mg/kg doses. Both sexes of mice
had myelold depletion of the bone marrow at doses >250 mg/kg. Doses of >250
1830A 7-21 03/17/84
-------
mg/kg caused necrosis of the thymus and doses of >500 mg/kg caused lymphold
depletion 1n the thymus. Based on these results, 60 mg/kg should be
considered a lowest-observed-adverse-effect level (LOAEL).
The rat study resulted 1n a 13-week survival rate of 90% (9/10), 100%
(10/10), 100% (10/10), 100% (10/10), 60% (6/10) and 10% (1/10) 1n male rats
and 100% (10/10), 100% (10/10), 100% (10/10), 100% (10/10), 70% (7/10) and
20% (2/10) 1n female rats for the 0, 60, 125, 250, 500 and 750 mg/kg dose
groups, respectively (NTP, 1983b). Body weight gains over the 13-week
period were depressed by 10% or more 1n the male rats receiving doses >250
mg/kg and 1n female rats receiving 500 and 750 mg/kg doses. The only
hematologlc effects noted were at the 750 mg/kg dose level 1n surviving
males (Increased retlculocyte percentage) and females (decreased white blood
cell count). The only consistent effects observed 1n the serum chemistries
were slightly Increased activities of y-Qlutamyl transpeptldase and
alkaline phosphatase 1n female rats receiving 500 and 750 mg/kg. The 750
mg/kg male rats were observed to have a doubling of their 24-hour urine
output. Increased urinary excretion of uroporphyMns was observed In male
rats at 750 mg/kg dose and of coproporphyrlns 1n male rats at 500 and 750
mg/kg doses and 1n female rats at 500 mg/kg dose. No changes were observed
1n hepatic porphyrln levels. At sacrifice, monochlorobenzene-related
histologlcal changes were found 1n the liver, kidney, bone marrow, spleen
and thymus. Liver lesions were classified as centrllobular hepatocellular
necrosis (minimal at 250 mg/kg, minimal to moderate at 500 mg/kg, and moder-
ate at 750 mg/kg for both sexes of rats). M1ld to moderate nephropathy was
observed 1n male and female rats at 750 mg/kg and 1n male rats at 500 mg/kg.
Both male and female rats exhibited lymphold depletions of the thymus and
1830A 7-22 03/17/84
-------
spleen at the 750 mg/kg dose and myelold depletion of the bone marrow at the
500 and 750 mg/kg doses. From these rat data the lowest-observed-adverse-
effect level (LOAEL) 1s 250 mg/kg and the NOEL 1s 125 mg/kg.
7.3.3. Chronic Tox1c1ty. Two-year chronic bloassay studies using
monochlorobenzene were conducted under the auspices of the National Toxico-
logy Program (NTP, 1983b). The Investigations were conducted using 50 male
and 50 female B6C3F, mice and 50 male and 50 female F344/N rats. Mono-
chlorobenzene was administered by gavage 1n a corn oil vehicle, 5 mil/kg, 5
days/week for 103 weeks. The dosage groups used were untreated, 0, 60 and
120 mg/kg for male and female rats and female mice, and untreated, 0, 30 and
60 mg/kg for male mice.
The mouse study revealed no monochlorobenzene-related clinical signs of
toxldty or differences 1n mean body weights among test groups during the
105-week test period (exposure duration 103 weeks). Survival rates over the
test period 1n the male m1c,e were 70% (35/50), 78% (39/50), 56% (28/50) and
58% (29/50) for the untreated control, vehicle control (0), 30 and 60 mg/kg
dose groups, respectively. Survival rates for the female mice were 74%
(37/50), 80% (40/50), 82% (41/50) and 76% (38/50) for the untreated
controls, vehicle controls (0), 60 and 120 mg/kg dose groups, respectively.
The only monochlorobenzene dosed group found to be significantly different
from controls 1n survival rates was the 30 mg/kg male group (p=0.031).
H1stolog1cal findings of neoplasms will be discussed In Section 7.3.5.
Carc1nogen1c1ty. No statistically significant Increased or decreased
Incidences 1n site-specific tumors or non-neoplast1c pathology were found 1n
either the male or female mice (NTP, 1983b).
The rat study revealed no monochlorobenzene-related clinical signs of
toxldty during the 104-week study period (exposure duration 103 weeks).
1830A 7-23 03/27/84
-------
The only differences noted 1n body weights during this study were Increased
body weights 1n the monochlorobenzene-treated females during the second
study year. The only significant differences 1n survival rates were
observed 1n the male 120 mg/kg dose group which had significantly reduced
survival rates (p=0.014 as compared with vehicle control). The survival
rates during this study were 68% (34/50), 78% (39/50), 64% (32/50) and 52%
(26/50) 1n male rats and 74% (37/50), 58% (29/50), 60% (30/50) and 62%
(31/50) 1n female rats for the untreated controls, vehicle controls (0), 60
and 120 mg/kg dose groups, respectively. H1stolog1cal findings of neoplasms
will be discussed 1n Section 7.3.5. Carc1nogen1c1ty. Hlstologlcal evalua-
tion of liver tissue provided equivocal evidence for mild monochlorobenzene-
Induced hepatocellular necrosis. The control rat livers were observed to
have more basophlUc cytoplasmlc changes than the monochlorobenzene-treated
rats (NTP, 1983b).
7.3.4. MutagenlcUy. Studies of the mutagenlcHy of monochlorobenzene
have yielded mixed results, with the greater proportion of the studies being
negative (Table 7-5).
7.3.5. Carc1nogen1c1ty. The only study available on the assay of mono-
chlorobenzene for carcinogenic potential 1s one conducted by the National
Toxicology Program (NTP), 1983. This study was carried out with F344/N rats
and with B6C3F mice. In both the rat and mouse tests the compound was
prepared 1n corn oil and administered by gavage, on a 5 day/week schedule,
for 103 weeks to groups of 50 male and 50 female animals at each dose. The
doses selected 1n the rat study were 60 and 120 mg/kg/day for both male and
female animals while 1n the case of mice the females received 60 or 120
mg/kg/day but the males received 30 or 60 mg/kg/day. The test compound was
99% pure.
1830A 7-24 03/27/84
-------
TABLE 7-5
CO
CO
o
-J
1
l\>
tn
o
co
«-x
0
Vv
as
Test System
Asperlqlllus nldulans
Salmonella strains
TA1535, TA1537, TA1538,
TA92, TA98, TA100
Salmonella typhlmurlum
strains
Salmonella typhlmurlum
strains
Saccharomyces cerevlslae
Saccharomyces cerevlslae
Mouse lymphoma L5178Y
(forward mutation of TK)
DNA repair:
Escherlchla coll
(polAVpolA")
Bacillus subtms
(rec~/rec+)
Streptomyces antlblotlcus
11 n u ~ ». _n«.-..j.n.-i
Mutagenldty Testing of Monochlorobenzene
Metabolic Concentration
Activation
200 pg/mt
+ 0.1-0.5 pi/plate
+ 100 vg/plate
+ 150-3000 yg/plate
+ 0.05-6%
4 0.01-5 vl/plaie
0.001-0.1 yl/mt
t 0.0001-0.01 yt/ml
10-20 yft/plate
10-20 pit/plate
NR
Result
negative
negative
negative
negative
positive
negative
negative
negative
negative
positive
Reference
Prasad, 1970
Simmon et al. ,
1979
Merck, 1978
DuPont, 1977
Simmon et al . ,
1977
Monsanto, 1976
Monsanto, 1976
Simmon et al. ,
1979
Simmon et al. ,
1979
Kesklnova, 1968
-------
7.3.5.1. RAT STUDY -- In the case of the F344/N rats, dose selection
was made as a result of observations 1n the 13 week subchronlc study. In
the 13-week study doses of 60, 125, 250, 500 and 750 mg/kg for each day of
dosing were used. There was essentially 100% survival among both sexes up
to and Including the 250 mg/kg groups; at 500 mg/kg/day the mortality was
30-40% and at the top dose, 750 mg/kg, the mortality was 80-90%. Among male
rats the body weight gain was depressed by 12% relative to the controls for
250 mg/kg or higher, and 12% or greater among females at the 500 and 750
mg/kg groups. Hlstopathology was carried out on all the major organs for
rats 1n the 500 and 750 mg/kg groups, on kidneys, bone marrow and liver for
animals 1n the 250 mg/kg groups and only on liver and kidney In the 125
mg/kg groups. Hepatic necrosis was seen 1n 2/10 males and 1/10 females at
250 mg/kg and occurred with greater frequency 1n the higher dose groups.
Other toxic manifestations Including nephrotoxldty, lymphold and myelold
depletion of spleen, bone marrow and thymus, and abnormal porphyrln metabo-
lism occurred at the 500 mg/kg and higher doses. These findings on surviv-
al, weight decrement and pathology formed the basis for selection of the 60
and 120 mg/kg dosages for the 2-year study 1n the rats.
In the 2-year study survival of males at the 120 mg/kg groups was
significantly reduced when compared with vehicle but not with untreated
controls. It 1s not clear whether the accidental deaths were censored from
this evaluation. There were four such accidental deaths among the high dose
males, two at the low dose and one 1n a vehicle control male. Among females
there were seven accidental vehicle control deaths, four at the low dose and
two at the high dose.
The hlstopathology review In the 2-year study resulted 1n conflicting
Interpretation by different pathologlsts with respect to hepatocellular
1830A 7-26 03/23/84
-------
necrosis, hepatocellular basophlUc cytoplasmlc changes and granulomatous
Inflammation. The findings of the 2 different reviewers are given, as they
appear 1n the NTP report, 1n Table 7-6. It 1s not clear whether these
differing Interpretations of non-neoplast1c lesions have any bearing on the
single set of results reported for neoplastlc nodules and carcinomas (Table
7-7). In males no carcinomas were observed In the treated groups, but there
was a statistically significant Increase 1n neoplastlc nodules 1n the high
dose group and a marginally significant dose-response trend. Neither neo-
plastlc nodules nor hepatocellular carcinoma were Increased 1n female rats.
In this study Interstitial cell tumors of the testls showed a signifi-
cant positive trend and the Incidence 1n the high dose group was signifi-
cantly different from the vehicle control 1n the life-table test. These
statistics are, however, without biological significance since the untreated
controls had Incidence of 100%. The vehicle control had 93.7% Incidence and
the low dose 97.7% while the high dose had 100%.
Both pituitary tumors (adenomas 1n female rats and combined adenomas and
carcinomas 1n male rats) and endometrlal stromal polyps of the uterus showed
significant negative trends.
In the F344/N rats, therefore, the significant Increase 1n neoplastlc
nodules 1n the liver of male animals at the 120 mg/kg/day dose group
provides some evidence for tumor1gen1c1ty of monochlorobenzene.
7.5.3.2. MOUSE STUDY -- The choice of dose for the chronic study 1n
mice was based on the results of a 13 week subchronlc test. In the 250
mg/kg group of the 13-week study 4/9 males died (time of death was 1 week
for one animal and 10 weeks for the other three animals), and there was a
20% weight decrement compared to controls, showing clear evidence of toxlc-
1ty. In the next lower test group (125 mg/kg), no males died and the
1830A 7-27 03/23/84
-------
TABLE 7-6
Nonneoplastlc Lesions 1n F344 Rats Given Chlorobenzene
by Gavage for 2 Years*
Males
UC VC
Low
Dose
High
Dose
Females
UC VC
Low
Dose
High
Dose
Number of livers
examined
50 50
49
49
49 50
50
50
Hepatocellular
necrosis
Cytoplasmlc
basophlUa change
Inflammation
First Reading
214 5
25 27 6 3
38 27 18 10
23 21 11 11
Hepatocellular
necrosis
Cytoplasmlc
basophlUa change
Second Reading
325 1
28 40 12
12
1 1
43 34 26
18
*Source: NTP draft, 1983b
UC = Untreated controls; VC = vehicle controls
1830A
7-28
04/16/84
-------
TABLE 7-7
Statistical Comparisons of Liver Tumors 1n Male Rats Treated with
Chlorobenzene and Vehicle Controls*
Untreated
Control
Vehicle
Control
60 mg/kg 120 mg/kg
Neoplastlc nodule
Overall
Adjusted
Terminal
Life Table
Incidental
Test
4/50(8%)
10.4%
2/34(6%)
Tumor
Cochran-Armltage Trend,
Fisher Exact Tests
Carcinoma
Overall
Adjusted
Terminal
Life Table
Incidental Tumor Test
Cochran-Armltage Trend,
Fisher Exact Tests
Neoplastlc Nodule or Carcinoma
Overall
Adjusted
Terminal
Life Table
Incidental Tumor Test
Cochran-Armltage Trend,
Fisher Exact Tests
0.50(0%)
0.0%
0/34(0%)
4/50(8%)
10.4%
2/34(6%)
2/50(4%)
4.5%
0.39(0%)
P=0.005
P=0.011
P=0.027
2/50(4%)
5.1%
2/39(5%)
P=0.139N
P=0.139N
4/50(8%)
9.4%
2/39(5%)
P=0.033
P=0.054
P=0.121
4/49(8%)
12.5%
4/32(13%)
P=0.255
P=0.290
P=0.329
0/49(0%)
0.0%
0/32(0%)
P=0.283N
P=0.283N
P=0.098N P=0.253N
4/49(8%)
12.5%
4/32(13%)
P=0.532
P=0.570
P=0.631
8/49(16%)
29.3%
7/26(27%)
P=0.010
P=0.021
P=0.043
0/49(0%)
0.0%
0/26(0%)
P=0.331N
P=0.331N
P=0.253N
8/49(16%)
29.3%
7/26(27%)
P=0.048
P=0.083
P=0.168
*Source: NTP draft, 1983b
1830A
7-29
04/16/84
-------
average weight was within 6% of the controls, The hlstopathology review of
the 125 mg/kg group showed one male mouse with hepatic necrosis. There was
also one male with hepatic necrosis 1n the 60 mg/kg/day group. On the basis
of these data one can conclude that doses up to 120 mg/kg probably could
have been tolerated 1n the chronic study of male mice, whereas only 60 and
30 mg/kg were actually used. However, the NTP draft document (dated Feb.
28, 1983) stated that "doses of 30 and 60 mg/kg were selected for male mice
because of a perceived greater susceptibility of this sex to the toxic
effects of chlorobenzene".
The survival and body weight data 1n males during the chronic study also
suggest that larger doses could have been tolerated. Body weights 1n both
dose groups and survival 1n the high dose group were comparable to controls.
Although survival was reported to be significantly reduced In the low dose
group (30 mg/kg), two animals that died had foreign material 1n the lungs,
suggesting that gavage errors rather than toxldty was responsible for the
reduced survival 1n that group. These two animals were Included as deaths
from natural causes.
After hlstopathologlcal analysis the NTP found that both tumor Incidence
and non-neoplast1c pathology were comparable to controls at all sites 1n
both male and female treated groups. The test 1n mice therefore provided no
evidence of carclnogenlcHy at doses as high as 60 mg/kg. Note, however
that the F344/N rats did not develop neoplastlc nodules until the dose was
as high as 120 mg/kg.
In summary, the evidence for the carclnogenlcHy of monochlorobenzene
from the NTP study on F344/N rats and B6C3F mice consists of the finding
of a significant Increase 1n neoplastlc nodules 1n the liver 1n male rats
that received 120 mg/kg, for 5 days/week for 2 years. If the IARC criteria
1830A 7-30 03/23/84
-------
for classifying carcinogens were used, this evidence would be characterized
as limited to Inadequate 1n animals. Since there 1s no human evidence
relating to carc1nogen1dty, the overall IARC classification 1s category 3,
and no conclusions can be made concerning the cardnogenlclty of monochloro-
benzene 1n humans.
7.3.6. Reproductive and Teratogenlc Tox1c1ty. Monsanto Company (1978)
reported effects on the gonads of dogs exposed to monochlorobenzene vapor at
0, 0.76, 1.47 and 2.0 mg/J. for 6 hours/day, 5 days/week for a total of 62
exposures. Two of four male dogs 1n the high dose group developed bilateral
atrophy of epithelial tissue 1n the seminiferous tubules. These effects are
consistent with an earlier Monsanto (1967a) study where four male and four
female dogs were orally given monochlorobenzene at 0.025, 0.050 and 0.250
mg/kg/day doses for 13 weeks. Three of the four male dogs 1n the high dose
group had decreased spermatogenesls and this group also had tubular atrophy
and epithelial degeneration.
Rats exposed to monochlorobenzene vapor at 0, 0.76, 1.47 and 2.0 mg/8.
for 6 hours/day, 5 days/week for a total of 62 exposures showed less
definite gonadal responses (Monsanto, 1978). The 2.0 mg/l exposed female
rats exhibited significantly higher gonad-to-body-we1ght ratio when compared
to control females.
No studies regarding the teratogenlclty of monochlorobenzenes were
available for review.
7.4. INTERACTIONS
Monochlorobenzene produces a variety of alterations 1n enzyme function
and would, therefore, be expected to Influence the metabolism and toxldty
of a variety of compounds. Shelton and Weber (1981) Investigated the hepa-
totoxlclty of a mixture of CC1 and monochlorobenzene (1:38 molar ratio)
1830A 7-31 03/23/84
-------
to male CF-1 mice. The mixture was given 1ntraper1toneally 1n corn oil
(0.01 m8./g bw). For the mixture of CC1. and monochlorobenzene, the
plasma anallne amlnotransferase dose-response curve did not deviate from
that predicted on the basis of dose addition.
7.5. SUMMARY
Acute exposure to monochlorobenzene by Inhalation causes sensory Irrita-
tion of the respiratory system after a few minutes; exposure for several
minutes to several hours causes narcosis and central nevous system depres-
sion, which can result 1n death. It 1s also toxic by the oral or parenteral
routes. Systemic effects of acute toxic doses Include kidney damage.
Subchronlc Inhalation exposure at 1.0 mg/m3 (contlnously for 60 days)
causes neurotoxlc effects 1n rats, an Increase 1n blood chollnesterase and
abnormal chronaxla of the muscles. Repeated exposure of rats to monochloro-
benzene at 250 ppm (1157 mg/m3) causes slight changes 1n the liver,
kidneys and adrenal cortex. Repeated oral dosing of rats or dogs (100-200
mg/kg/day) causes some toxic manifestation 1n the liver and kidneys.
Gavage administration of monochlorobenzene to mice and rats 5 times/week
for 13 weeks resulted 1n Increased mortality 1n the higher dose groups (>250
mg/kg), urinary porphyrla and dose-dependent Injury to the liver, kidney,
bone marrow, spleen and thymus. A set of similar studies were conducted 1n
mice and rats for 2 years and resulted 1n some Increased mortality 1n the
male monochlorobenzene exposed groups when compared with controls. Only
equivocal evidence for mild monochlorobenzene-lnduced hepatocellular
necrosis was found 1n rats.
Although one study 1n Streptomyces found monochlorobenzene to Induce
reversion to vitamin B prototrophy and one study 1n Saccharomyces cejre-
vlslae showed Increased mltotlc crossing over (Indication of DNA damage),
1830A 7-32 04/17/84
-------
several other studies with bacterial, fungal and mammalian tissue culture
systems were negative. The carcinogenic activity of monochlorobenzene was
tested 1n the NTP bloassay program 1n two rodent species at doses of 60 and
120 mg/kg bw/day 1n male and female rats and female mice, and at 30 and 60
mg/kg bw/day 1n male mice. Cardnogenldty was not demonstrated for
monochlorobenzene by this study.
Repeated exposures to monochlorobenzene at 2.0 mg/l (vapors) or 0.250
mg/kg/day (oral) were found to cause atrophy of the epithelial tissue of the
seminiferous tubules and decreased spermatogenesls 1n male dogs and rats and
Increased gonad weight/body weight ratios 1n female rats.
1830A 7-33 03/17/84
-------
8. DICHLOROBENZENES
The 1983 annual production of dlchlorobenzenes 1n the United States 1s
estimated to be between 46.7 and 50.2 million kilograms (U.S. EPA, 1983).
These materials are used primarily as fumlgants, Insecticides, solvents, dye
carriers and space deodorants (Hawley, 1977). Measurable levels of
dlchlorobenzenes have been reported 1n ambient urban and rural air and 1n
samples of Indoor air, 1n ground, surface and wastewater and In runoff from
hazardous waste sites (see Section 4.3.). Residues have been found 1n fish
and other aquatic organisms and 1n samples of human fat, blood, breath and
urine (see Section 4.3.3.). Human exposure 1s most likely through the
Inhalation of air and Ingestlon of contaminated food and drinking water.
8.1. PHARMACOKINETICS
8.1.1. Absorption. The dlchlorobenzenes have low water solubility and
high I1p1d solubility and therefore are likely to diffuse through most bio-
logical membranes, Including the surfaces of the lungs and gastrointestinal
tract and the skin. The absorption of dlchlorobenzenes by humans Is
Indicated by poisonings that have resulted from exposures by Inhalation or
Ingestlon. Quantitative studies of the absorption of dlchlorobenzenes 1n
humans and animals are lacking. The available data Indicate that absorption
does occur fairly rapidly through the lungs and gastrointestinal tract.,
Skin absorption has not been tested adequately.
Twenty-three cases of poisoning by dlchlorobenzenes have been reported
In the available literature and provide evidence of human absorption
(Downing, 1939; Perrln, 1941; PetH and Champelx, 1948; Sumers et al., 1952;
Weller and Crellln, 1953; Cotter, 1953; Hallowell, 1959; Frank and Cohen,
1961; Gadrat et al., 1962; Nalbandlan and Pearce, 1965; Glrard et al., 1969;
Campbell and Davidson, 1970; Ware and West, 1977; Harden and Baetjer, 1978).
1831A 8-1 03/29/84
-------
Of these cases, 5 Involved 1,2-d1chlorobenzene as the principal or signifi-
cant source of exposure and 11 Involved 1,4-d1chlorobenzene. Inhalation was
the primary route of exposure for 17 of the cases and 3 Involved Ingestlon.
Three of the cases also mentioned previous dermal exposures that may have
contributed to the reported Intoxication.
Hawkins et al. (1980) exposed ten female CFY rats to a nominal air con-
centration of 1000 ppm of l,4-d1chloro-[l4C]benzene, 3 hours/day for up to
10 days. In parallel experiments, groups of 20 female CFY rats were given
dally oral or subcutaneous doses of 1,4-d1chloro-[l4C]benzene dissolved In
sunflower oil. Twenty-four hour tissue concentrations of 14C were similar
for each treatment route, with the highest concentrations occurring 1n the
fat, kidneys, liver and lungs. 1,4-D1chlorobenzene appears to be well
absorbed through both the lungs and gastrointestinal tract; however, no
quantitative measures of absorption were attempted.
Klmura et al. (1979) administered 200 or 800 mg/kg of 1,4-d1chloroben-
zene 1n corn oil orally to male Wlstar rats and monitored the appearance of
the chemical 1n blood, adipose, kidney, liver, lung, heart and brain tissue.
At the first time point, 30 minutes after dosing, all these tissues con-
tained measurable amounts of dlchlorobenzene, with liver and adipose tissue
having 2 and 10 times the concentrations seen 1n the blood, respectively.
Throe other studies have suggested that dlchlorobenzenes can be almost
completely absorbed from the gastrointestinal tract, even when present 1n
low doses. Azouz et al. (1955) dosed chinchilla rabbits Intragastrlcally
with 1.5 g 1,4-d1chlorobenzene/rabb1t 1n olive oil and did not detect any of
the compound 1n the feces, Implying that under the conditions of this study,
a total absorption had occurred. Hawkins et al. (1980) administered a
single dose of labeled 1,4-d1chlorobenzene (250 mg/kg) to rats with
1831A 8-2 03/29/84
-------
cannulated bile ducts, which prevented fecal excretion of the metabolized
compound. During the following 24 hours, 9% of the label was present 1n the
feces, representing the unabsorbed portion of the dose. l,2-D1chlorobenzene
and other organic contaminants of water were administered to rats In the
diet at levels of 0.4-2 mg/kg/day (Jacobs et al., 1974a,b). The accumula-
tion of the compound 1n several tissues Indicated that absorption occurs
after the 1ngest1on of low levels of 1,2-d1chlorobenzene.
Rledel (1941) has Investigated the dermal absorption of l,2-d1chloro-
benzene 1n rats. No quantitative measurements were made; however, five
applications were lethal when the compound was applied directly to a 10
cm2 area of abdominal skin.
Absorption of dlchlorobenzenes can occur through the lungs, skin and
gastrointestinal tract. Quantitative studies of absorption through the
lungs and gastrointestinal tract are lacking, as well as studies on dermal
absorption.
8.1.2. Distribution. The low water and high I1p1d solubility of the
dlchlorobenzenes enable their diffusion through membranes and therefore
enhance their tissue distribution. Several studies 1n animals have quanti-
fied the degree and time course of the distribution of dlchlorobenzenes
after Inhalation and 1ngest1on and Indicate rapid distribution to blood,
adipose, kidney, liver, lung, heart, brain and muscle tissue.
Hawkins et al. (1980) Investigated the distribution and excretion of
l,4-d1chlorobenzene In adult female CFY rats (derived from Sprague-Dawley
rats) after repeated Inhalation, oral and subcutaneous doses. Rad1oact1vely
labeled 1,4-d1chlorobenzene was administered by exposing groups of 10 rats
to the compound at an atmosphere of 1000 ppm for 3 hours/day for 10 consecu-
tive days or by oral or subcutaneous doses of 250 mg/kg/day for 10 days.
1831A 8-3 03/29/84
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The Investigators reported tissue concentrations after 2, 4, 6, 8 and 10
doses. Radlolabel was widely distributed following each route of adminis-
tration, with the highest concentrations occurring 1n fat, kidney, liver and
lungs (Table 8-1).
Klmura et al. (1979) also provided Information on the distribution of
1,4-d1chlorobenzene. Tissue levels of the compound were monitored at
Intervals from 30 minutes to 120 hours 1n male Wlstar rats given a 200 mg/kg
oral dose 1n corn oil after a 16-hour fast. At the first Interval, fat and
liver levels were 10 and 2 times the blood levels (~9 pg/ml), respec-
tively, with lower concentrations of dlchlorobenzene appearing 1n all of the
other tissues examined (kidney, lung, heart and brain). Levels 1n fat,
kidney and liver tissue peaked between 6 and 12 hours (at -50, 2 and 0.5
times blood levels, respectively) and thereafter, decreased along with the
levels 1n the other tissues. After 48 hours, concentrations of l,4-d1-
chlorobenzene were below the detection limit 1n all tissues examined, except
for fat tissue, which had detectable levels equal to approximately one-
fiftieth of peak concentrations at 120 hours post-administration.
Tissue distribution after subchronlc feeding of 1,2-d1chlorobenzene was
Investigated by Jacobs et al. (1974a,b), who administered the compound 1n a
mixture of other organic chemicals at doses of 0.4, 0.8 and 2 mg/kg/day for
4-12 weeks to rats. A dose-related accumulation of 1,2-d1chlorobenzene was
reported 1n abdominal and renal adipose tissue to an extent greater than
that seen 1n liver, heart and blood tissues.
Studies of tissue distribution of dlchlorobenzenes after repeated
Inhalation exposure and single and subchronlc oral exposure Indicate that
the chemicals appear 1n all of the major tissues soon after dosing with the
1831A 8-4 03/29/84
-------
CD
CO
TABLE 8-1
Tissue Concentrations of 1,4-D1chlorobenzene In Adult Female CFY Ratsa«b-c
(ppm)
Number
of Doses
CD
i
en
2
4
6
8
10
Liver
Inha1at1onc Oral
14
22
28
16
18
11
18
14
15
9
Subcutaneous
21
22
24
21
20
Inhalation
24
40
43
28
27
Kidneys
Oral Subcutaneous
27
29
23
18
16
30
32
47
41
32
Inhalation
9
12
11
10
10
Lunqs
Fat
Oral Subcutaneous Inhalation Oral
7
13
10
11
9
18
12
14
21
17
418
579
597
433
337
218
369
170
131
257
Subcutaneous
372
302
269
554
383
aSource: Adapted from Hawkins et al., 1980
bFema1e rats were exposed dally to 1,4-dlchlorobenzene via: Inhalation, 1000 ppm for 3 hours/day; oral, 250 mg/kg 1n sunflower oil;
subcutaneously, 250 mg/kg 1n sunflower oil and killed 24 hours after last dosing.
cValues represent the average from two animals
o
CO
CD
-------
highest levels, 1n descending order, 1n adipose, kidney, liver and lung
tissue. Peak concentrations are reached 1n all tissues within 4-12 hours,
followed by almost total elimination (Section 8.1.4.). The pattern of dis-
tribution after Inhalation, subcutaneous and oral administration 1s similar.
8.1.3. Metabolism. The metabolism of the dlchlorobenzenes has been
Investigated primarily 1n rabbits and rats; few data were available on
metabolism 1n humans. Several studies have shown the primary metabolites to
be dlchlorophenols that are conjugated with glucuronlc and sulfuMc adds
and excreted. Formation of the dlchlorophenols from 1,2- and 1,3-d1chloro-
benzene appears to Involve epoxldase and arene oxide Intermediates.
Azouz et al. (1955) studied the metabolism of 1,2- and 1,4-d1chloroben-
zene 1n rabbits given oral doses of 500 mg/kg. The compounds were metabo-
lized primarily through oxidation to 3,4-d1chlorophenol (from 1,2-d1chloro-
benzene) and 2,5-d1chlorophenol (from 1,4-d1chlorobenzene) and excreted 1n
the urine 1n the form of glucuronlc and sulfurlc add conjugates. Minor
metabolites of 1,2-d1chlorobenzene Included the 4,5- and 3,4-d1chloro-
catechols and 3,4-d1chlorophenylmercaptur1c add; a minor metabolite of
l,4-d1chlorobenzene 1s 2,5-d1chloroqu1nol. Metabolism and complete elimina-
tion required 5-6 days for 1,2-d1chlorobenzene and >6 days for 1,4-d1chloro-
benzene. Klmura et al. (1979) found similar results 1n male Wlstar rats;
oral administration of 200 or 800 mg/kg of 1,4-d1chlorobenzene resulted 1n
the formation of one major metabolite, 2,5-d1chlorophenol, and two minor
sulfur-containing metabolites (<0.03X of the total dose). These two com-
pounds, Identified as 2,5-d1chlorophenol methoxy sulfoxlde and 2,5-dlchloro-
phenol methyl sulfone, were excreted over a 5-day period and were detected
1n blood, fat, kidney and liver tissues.
1831A 8-6 03/29/84
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Hawkins et al. (1980) Investigated the metabolism of radlolabeled
1,4-d1chlorobenzene 1n female CFY rats after repeated Inhalation (1000 ppm
for 3 hours/day), oral or subcutaneous (250 mg/kg/day) exposures. After
dosing for 10 consecutive days, all of the label was metabolized and elimi-
nated within 192 hours (8 days). Both routes of exposure resulted 1n simi-
lar urinary and biliary metabolites, primarily 2,5-d1chlorophenol sulfate
(46-54% of the total excreted) and 2,5-d1chlorophenol glucuronlde 1n the
urine (31-34%) and bile (30-42%). Two minor metabolites were Identified as
d1hydroxyd1chlorobenzene and a mercapturlc add of 1,4-d1chlorobenzene.
Parke and Williams (1955) studied the metabolism of 1,3-d1chlorobenzene
1n rabbits and found dlchlorophenol to be the major metabolite, accounting
for 40% of the total amount of excreted metabolites. 2,4-D1chlorophenyl-
mercapturlc add and 3,5-d1chlorocatechol were also detected. No analogous
studies have been conducted 1n humans although Pagnotto and Walkley (1966)
reported that 2,5-d1chlorophenol was present 1n the urine of men occupation-
ally exposed to 1,4-d1chlorobenzene by Inhalation. Several studies have
Indicated that the dlchlorobenzenes are also capable of Inducing hepatic
mlcrosomal enzymes and enhancing the synthesis of porphyrins. Rlmlngton and
Zlegler (1963), Poland et al. (1971) and Ar1yosh1 et al. (1981) have report-
ed the Induction of 5-am1nolevul1n1c add synthetase 1n rats by dally
doses of 250-1000 mg/kg of dlchlorobenzenes. This enzyme Is Involved In the
rate-limiting step of the synthesis of porphyrins and Its Induction 1s
necessary for an Increase in the activity of cytochrome P-450 and other
xenoblotlc metabolizing enzymes.
8.1.3.1. COVALENT BINDING — Metabolism of dlchlorobenzenes results
1n the formation of reactive spedes, which may bind covalently to cellular
macromolecules. This binding may lead to some toxic effects of the
1831A 8-7 03/29/84
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dlchlorobenzenes. Reid and Krishna (1973) studied the relationship between
the binding of metabolites of halogenated aromatic hydrocarbons and the
Induction of hepatic necrosis. Labeled bromobenzene, 1,2- and 1,4-d1chloro-
benzene, as well as other aromatic compounds, were Injected Intraperltoneal-
ly Into Sprague-Dawley rats 1n 0.5 mmol/kg doses. A correlation between
covalent binding of bromobenzene to protein and the time course and degree
of hepatic centrolobular necrosis was established. 1,2-D1chlorobenzene also
was found to bind to liver protein and the binding was enhanced by pretreat-
ment with phenobarbltal. 1,4-D1chlorobenzene showed little binding. The
authors Interpreted these results to mean that the hepatic Injury Induced by
1,2-dlchlorobenzene was a result of the binding to protein of reactive
Intermediates whose synthesis was Increased by the Induction of hepatic
xenob1ot1c-metabo!1z1ng enzymes. 1,4-D1chlorobenzene Is less hepatotoxlc
than 1,2-d1chlorobenzene and does not bind to the same degree. Similar
results were obtained for the bronchlolar necrosis occurring 1n lung tissue
{Reid et a!., 1973).
8.1.4. Excretion. Hawkins et al. (1980) measured the excretion of 14C
In female CFY rats following whole body exposure by Inhalation (1000 ppm, 3
hours/day, 2-10 days), by oral (250 mg/kg/day) or subcutaneous (250 mg/kg/
day) routes of 1,4-d1chloro[l4C]benzene. Excretion occurred primarily via
the urine (91-97% of the total excreted) over a 5-day period after repeated
doslngs had stopped, with only minor amounts occurring 1n the feces and
expired air. Following a single oral dose to blle-duct-cannulated rats,
46-63X of the 14C excreted during the first 24 hours was found In the
bile. This Implies that enterohepatlc reclrculatlon occurs to a major
extent with this compound. Excretion seemed to Involve a rapid Initial
phase followed by a slower extended excretion phase.
1831A 8-8 03/01/84
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Klmura et al. (1979) observed similar excretion patterns 1n male Wlstar
rats. They suggested that the prolonged excretion of 1,4-d1chlorobenzene
resulted from the release of unmetabollzed material from fatty depots and
the slow excretion rates for 2,5-d1chlorophenyl methyl sulfone and
2,5-d1chlorophenyl methyl sulfoxlde, two metabolites of 1,4-d1chlorobenzene.
Azouz et al. (1955) compared the excretion of 1,2-d1chlorobenzene and
1,4-d1chlorobenzene given to chinchilla rabbits by stomach tube 1n an olive
oil solution. Excretion rates were not determined; however, the excretion
of the ortho Isomer appeared to be complete within 5-6 days after dosing.
With the para Isomer, appreciable excretion of metabolites still occurred
after 6 days. Excretion of the meta Isomer 1n chinchilla rabbits was found
to be virtually complete wHhln 5 days after dosing by stomach tube using an
olive oil solution (Parke and Williams, 1955). One study has suggested that
similar metabolic products occur 1n humans. Pagnotto and Walkley (1966)
reported that the appearance of dlchlorophenol 1n the urine of workers that
were exposed to 1,4-d1chlorobenzene began soon after exposure, peaked at the
end of the shift and continued for several days.
8.1.5. Summary. The available data for rats, rabbits and humans Indicate
that the dlchlorobenzenes are absorbed through the lungs, gastrointestinal
tract and Intact skin, though actual determinations of absorption rates were
not located. Once absorbed through either Inhalation or 1ngest1on, the
dlchlorobenzenes are rapidly distributed to many tissues, Including blood,
adipose, kidney, liver, lung, heart, brain and muscle tissues. Distribution
1s primarily to adipose tissue, which has Initial levels 10-32 times the
blood concentrations and to lung and kidney tissues to a greater extent than
liver, muscle and plasma. Single-dose and repeated exposures by both
Inhalation and 1ngest1on show similar patterns of distribution. Elimination
1831A 8-9 03/29/84
-------
of the dlchlorobenzenes and their metabolites occurs within 5-6 days after
exposure, although elimination from adipose tissue Is slowest and l,2-d1-
chlorobenzene and metabolites are eliminated slightly more rapidly than
1,4-d1chlorobenzene. The dlchlorobenzenes are primarily metabolized by
hydroxylatlon to their respective dlchlorophenols, which are excreted 1n the
urine In the form of glucuronlc and sulfurlc add conjugates. Some metabo-
lites are excreted 1n the bile, although the majority are then reabsorbed by
the enterohepatlc pathway and reexcreted 1n the urine. Intermediates of the
metabolism of 1,4-d1chlorobenzene, possibly arene oxides, bind to liver
protein and may be Involved 1n the Induction of hepatotoxiclty.
8.2. EFFECTS ON HUMANS
8.2.1. Occupational Studies. One occupational study was available for
review. Zapata-Gayon et al. (1982) performed chromosomal studies on 8 males
and 18 females who were accidentally exposed to vapors of 1,2-d1chloroben-
zene for four 8-hour workdays. Karyotypes of cells from samples of periph-
eral blood from the exposed subjects were compared with those obtained from
16 controls (8 male, 8 female). Exposed subjects and controls had similar
occupational histories: all worked 1n a biological laboratory performing
electron microscope and tissue culture work. Recent history of prolonged
X-ray exposure, Infection or exposure to other toxic chemicals was not found
among the subjects. The exposure to 1,2-d1chlorobenzene, which resulted
from Us use as a pest control 1n the basement of a one-story building,
caused dizziness, headache, fatigue, nausea and eye and nose Irritation 1n
all but four of the subjects. Karyotype analysis, performed Independently
by two cytogenetldsts, found that the total number of altered cells, Iden-
tified as having clastogenlc chromosomal alterations, was greater 1n the
exposed versus control groups (8.9 vs. 2.0%, p<0.001, multiple ch1-square
1831A 8-10 03/29/84
-------
tests). In addition, the total number of single chromosomal breaks (6.2 vs.
0.9%, p<0.001) and double breaks (6.4 vs. 1.6X, p<0.001) were different. A
follow-up study was conducted on 15 of the original exposed cases 6 months
after the Initial exposure. The Investigators reported that the number of
altered cells and single breaks was not significantly different (p<0.05)
from the original control frequencies, but that the number of double breaks
was Increased (3.7 vs. 1.6X, p<0.01). No analysis of the number of altered
cells/person was performed, although these data, reported 1n the form of a
histogram, showed distinct differences (Table 8-2). The Investigators also
noted the presence of other aberrations (polyploldy and ring formation) that
were not statistically significant.
8.2.2. Case Studies. Numerous case studies have been reported In the
literature Involving both long-term occupational exposure and accidental or
deliberate acute exposure. Of these cases (a total of 23), 17 have Involved
exposure primarily through Inhalation, 3 through 1ngest1on and 3 most likely
through dermal absorption. The principal agent In 16 of these exposures was
1,4-d1chlorobenzene; the remainder Involved 1,2-d1chlorobenzene or mixtures
of all three dlchlorobenzene Isomers. In all of these cases, toxic effects
have been reported 1n one or more of the following: liver; blood, Including
ret1culoendothel1al system; central nervous system; and respiratory tract.
A summary of these reports, which were compiled 1n U.S. EPA (1980c) with the
exception of Hardln and Baetjer (1978), 1s given 1n Table 8-3.
Two surveys of the health of workers occupationally exposed to
1,4-d1chlorobenzene during Us manufacture have been reported. Holllngs-
worth et al. (1956) reported that periodic medical examinations showed no
evidence of Injury or adverse changes In hematology or eye lenses In workers
1831A 8-11 03/29/84
-------
TABLE 8-2
Chromosomal Alterations 1n Persons Accidentally
Exposed to l,2-D1chlorobenzene*
Number of Altered Cells per Person
0-1
2-3
4-5
>6
Percentage
Control
(n=16)
83
19
0
0
Exposed
(n=22)
5
35
29
31
*Source: Adapted from Zapata-Gayon et al., 1982
1831A
8-12
03/29/84
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as
TABLE 8-3
Case Reports Involving Dlchlorobenzenes (OCB)*
Chemical/Mixture
Subject and Exposure
Effects
Reference
1,2-DCB (vapor)
1,2-DCB solvent mixtures:
80* 1,2-DCB;
15X 1,4-OCB;
2X 1,3-DCB
1,2-DCB solvent mlxure:
95X 1,2-DCB;
5X 1,4-DCB
1,2-DCB and other chlorobenzenes
1,2-DCB In a mixture
1,2-DCB (37X In solution)
1,2-DCB solvent mixture:
BOX 1,2-DCB;
15X 1,4-DCB;
2X 1,3-DCB
1.4-DCB primarily
Sewage workers; occupational; Inhalation; efflu-
ent from dry cleaning establishment
Male, 40 years; occupational; use of solvent to
clean equipment; chronic dally exposure probably
via Inhalation of vapors, and dermal absorption
from clothing
Female, 18 years; occupational; chronic dally
Inhalation exposure to vapors as pressing-Ironing
worker
Hale, 60 years; occupational; filling barrels
with 1,2-DCB and other chlorobenzenes; chronic
Inhalation of vapors (last 3 years); perhaps
also skin contact
Male, 47 years; occupational; handling window
sashes dipped In mixture; chronic skin contact
(also Inhalation)
Female, 15 years; nonoccupatlonal; chronic
repeated dermal contact from compulsive use of
cleaning solution on clothing
Female, 55 years; nonoccupatlonal; chronic
repeated Inhalation of vapors from use of
solution to clean clothes; 1-2 I/year
Female, 30 years; occupational; chronic Inhala-
tion and dermal contact from 2 years of selling
mothballs and Insecticide products containing
1,4-DCB
Eye and upper respiratory
tract Irritation; vomiting
Weakness, fatigue; periph-
eral lymphadenopathy;
chronic lymphold leukemia
Severe acute hemolytU
anemia; leukocytosls, poly-
nucleosls; fatigue, nausea,
headache; bone marrow hyper-
plasla; possible Inherent
predisposing factor
Anemia
Contact eczematold derma-
titis on hands, arms, face,
erythema, edema; bullae 1n
response to skin test
Acute myeloblastlc leukemia
progressing to 100X leuko-
blastosls, hemorrhage and
death
Dupont, 1938
GUard et al., 1969
Gadrat et al., 1962
GUard et al., 1969
Downing, 1939
GUard et al.. 1969
Acute myeloblastlc leukemia GUard et al., 1969
Weakness, nausea, spleno-
megaly, "severe hepato-
cellular derangement, and
ensuing portal hyper-
tension" with esophageal
varlces
Sumers et al., 1952
-------
TABLE 8-3 (cont.)
Chemical/Mixture
Subject and Exposure
Effects
Reference
1,4-OCB primarily
1,4-OCB
1,4-DCB primarily
1,4-OCB
1,4-DCB
1,4-DCB
1,4-DCB
1,4-DCB
Female, 34 years; occupational; chronic Inhala-
tion from demonstrating 1,4-DCB products In booth
1n department store
Hale, 52 years; occupational; chronic Inhala-
tion of high vapor levels 1n a fur warehouse
Female, 19 years; occupational; crushing, pouring,
sieving, filling containers; poor ventilation;
chronic Inhalation of vapors
Female, occupational; casting 1,4-DCB 1n molds;
chronic Inhalation
Hale, 20 years and workmates; occupational;
1,4-DCB manufacturing activities, 1-7 months
of exposure; Inhalation
Hale, 62 years; nonoccupatlonal; used "moth
killer" product 1n bathroom at home, chronic
Inhalation of vapors, and wearing of Impreg-
nated clothing (possible skin exposure)
Female, 36 years; nonoccupatlonal; use of
commercial moth killer 1n home {presumably
Inhalation of vapors)
Hale, 60 years; nonoccupatlonal; 3-4 months
exposure to "moth gas vapor" 1n home
Halalse, then acute nausea,
vomiting, headache, jaun-
dice, hepatomegaly, spleno-
megaly, esophageal varlces,
and hemorrhoids; subacute
yellow atrophy and cirrhosis
of liver
Weakness, nausea, hemateme-
s1s, jaundice, emaciation,
petechla, hemorrhages;
hepatomegaly, splenomegaly,
hemorrhoids; protelnurla,
b1!1rub1nur1a; hematurla;
anemia, leukopenla; subacute
yellow atrophy of liver
Harked asthenia, dizziness,
weight loss; anemia and
reactlonal leukocytosls
Severe anemia
Weight loss, exhaustion,
and decreased appetite;
methemoglob1nem1a and
other blood pathologies
Asthenia, dizziness;
anemia, hypogranulocytosls
(similar to cases of In-
toxication by benzene)
Acute Illness with Intense
headache, profuse rhinitis,
perlorbltal swelling
Headache; weight loss;
diarrhea; numbness; clumsi-
ness; jaundice; enlarged
liver; anemia; neutropenla;
asdtes; death; acute
yellow atrophy of Hver
noted at autopsy
Cotter, 1953
Cotter, 1953
Petit and Champelx, 1948
Perrln, 1941
Ware and West, 1977
Perrln, 1941
Cotter. 1953
Cotter, 1953
-------
TABLE 8-3 (cont.)
Chemical/Mixture
Subject and Exposure
Effects
Reference
1,4-DCB
Female, wife of above, nonoccupatlonal; prolonged
severe exposure to "moth gas vapor"
1,4-DCB
oo
i
1.4-DCB
1.4-OCB
1,4-DCB
o
CO
X.
PO
o
03
Female, 53 years; nonoccupatlonal; used moth
eradlcator product heavily In home for 12-15
years, odor always apparent; chronic Inhalation
of vapor
Male, 3 years; nonoccupatlonal; played with
canister of demothlng crystals, spreading on
floor, handling; Ingestlon, likely acute
Female, 21 years; nonoccupatlonal; Ingestlon
during pregnancy (pica) of toilet air freshener
blocks at rate of 1-2/week
Female, 19 years; nonoccupatlonal; Ingestlon
(pica), 4-5 moth pellets dally for 2.5 years
Gradual loss of strength
and weight, then abdominal
swelling and jaundice
before acute Illness; ele-
vated temperature and pulse,
dilated vessels, swollen
liver, toxic granulocytosls;
died 1 year later; acute
yellow atrophy of liver,
Laennec's cirrhosis and
splenomegaly noted at autopsy
Chronic progressive cough
and dyspnea with mucold
sputum, wheezing, fatigue,
diminished breath sounds
and rales; abnormal lung
field on X-ray; flbrotlc.
rubbery lung with hlsto-
loglc changes; diagnosis:
pulmonary granulomatosls
Ustlessness, jaundice,
oUgurla, methemogloblnuHa
and other urine abnormali-
ties, anemia, hypothermia;
diagnosis: acute hemolytlc
anemia
Fatigue, anorexia, dizzi-
ness, edema of ankles;
hypochromlc mlcrocytlc
anemia; bone marrow normo-
blastlc hyperplasla; diag-
nosis: toxic hemolytlc
anemia; complete recovery
Increased skin pigmentation
1n areas 3-7 cm 1n diameter
on limbs; mental sluggish-
ness; tremor; upon with-
drawal, unsteady gait along
with decrease 1n pigmentation
Cotter, 1953
Heller and Crellln, 1953
Hallowell, 1959
Campbell and Davidson,
1970
Frank and Cohen, 1961
-------
TABLE 8-3 (cont. }
Chemical/Mixture
Subject and Exposure
Effects
Reference
1,4-DCB
Male, 69 years; nonoccupatlonal; dermal exposure,
presumably Interrupted; episode precipitated by
use of chair treated with 1,4-DCB
CD
i
1,4-DCB (and naphthalene)
Female, 68 years; occupational; Inhalation and
dermal exposure to mothproofing agents for 1
month/year for 39 years
Dyspnea followed by stiff
neck; "tightness" 1n chest,
"gas pains" 1n abdomen;
symmetrical petechla and
purpura on extremities,
swelling discomfort; stool
occult blood positive,
blood cells 1n urine; and
Increased BUN; basophll
degranul. test positive
for 1,4-DCB; diagnosis:
allergic (anaphylactold)
purpura and acute glomer-
ulonephrltls
Aplastlc anemia
Nalbandlan and Pierce,
1965
Harden and Baetjer. 1978
•Source: U.S. EPA. 1980c
o
CO
PO
10
oo
-------
exposed to airborne concentrations averaging 270-630 mg/m3. Workers com-
plained of eye and nose Irritation at levels >800 mg/m3. Another survey,
conducted at a 1,2-dlchlorobenzene manufacturing facility, reported ambient
levels of 6-264 mg/m3 (90 mg/m3 average) (Holllngsworth et al., 1958).
Occasional medical examinations, Including hematology and urlnalysls,
revealed no evidence of Injury or adverse hematologlc effects attributable
to the exposure.
8.2.3. Summary. Ep1dem1olog1c data are Insufficient to evaluate
dose-response associations. Possible chronic effects of exposure to the
dlchlorobenzenes are Indicated by case reports of the chronic exposure of
Individuals, I.e., repeated exposures over a period of more than a year,
suggesting a common set of toxic effects, those of the retlculoendothellal
and hematopoletlc systems and those of the liver. Of the 23 cases 1n the
literature, 17 Involved pathological changes 1n the blood or liver, Includ-
ing chronic lymphold leukemia, acute hemolytlc anemia, aplastlc anemia and
bone marrow hyperplasla. Although the exposures 1n these cases are not well
defined In time and often Involve other toxic substances, together they
suggest a common pathologic action of the dlchlorobenzenes on bone marrow
and other organs of the blood-forming system. The one available epidemic-
logic study (Zapata-Gayon et al., 1982) supports this generalization 1n that
the reported short-term exposure to 1,2-d1chlorobenzene (8 hours/day for 4
days) produced alterations In the chromosomes of leukocytes. This epldemlo-
loglc study did not establish an association between chromosomal alterations
and the pathologic changes that characterize the case studies.
8.3. MAMMALIAN TOXICOLOGY
8.3.1. Acute Toxldty. Many studies have Investigated the acute toxlclty
of 1,2- and 1,4-dlchlorobenzene, but no studies were available on
1831A 8-17 03/01/84
-------
l,3-d1chlorobenzene. In general, the acute toxic effects of 1,2- and
l,4-d1chlorobenzene have shown a similar profile of effects In all of the
species tested and depend to a certain degree on the route of administra-
tion. For oral administration, these effects Include, Initially, Increased
lacrlmatlon, salivation and excitation followed by ataxla, dyspnea and death
from respiratory paralysis usually within 3 days. On autopsy, the animals
were found to have enlarged livers with necrotlc areas, submucosal hemor-
rhages of the stomach, necrotlc changes of the kidneys and brain edema.
After acute Inhalation, the toxic effects observed were eye and nose Irrita-
tion, liver and kidney necrosis and central nervous system depression.
Lethal doses for both oral and Inhalation routes for 1,2-d1chlorobenzene
tend to be one-half to two-thirds of the values for 1,4-d1chlorobenzene.
Acute dermal application of 1,2-d1chlorobenzene results 1n local Irritation
and absorption of a lethal amount. Acute toxldty data for 1,2- and
1,4-dichlorobenzene, as compiled by U.S. EPA (1980), are given 1n Tables 8-4
and 8-5, respectively.
HolUngsworth et al. (1956, 1958) determined the acute oral toxldty of
1,2-d1chlorobenzene (50% 1n olive oil) 1n 10 guinea pigs of mixed sex and
l,4-d1chlorobenzene (20 or 50% 1n olive oil) 1n rats and (50% 1n olive oil)
1n guinea pigs. The Intubation of guinea pigs with 1,2-d1chlorobenzene 1n
single oral doses of 800 mg/kg resulted 1n loss of body weight, but was
survived by all subjects, whereas 2000 mg/kg doses were fatal to all
subjects. Intubation of rats and guinea pigs with 1,4-d1chlorobenzene 1n
single oral doses of 1000 mg/kg and 1600 mg/kg bw, respectively, were
survived by all the test animals, while doses of 4000 mg/kg and 2800 mg/kg
bw were found to be lethal to rats and guinea pigs, respectively.
1831A 8-18 03/29/84
-------
CD
3>
O3
i
5
O
CO
Species
Rat
Rat
Rat
Guinea pig
Guinea pig
Guinea pig
Rabbit
Rat
Mouse
Guinea pig
Rat
Mouse
Rabbit
Route of
Administration
Inhalation
Inhalation
Inhalation
Inhalation
oral
oral
oral
oral
oral
oral
dermal
Intravenous
Intravenous
Concentration
or Dose
5872 mg/m3
4249 mg/m»
3239 mg/m3
4808 mg/m3
2000 mg/kg
800 mg/kg
1875 mg/kg
2138 mg/kg
2000 mg/kg
3375 mg/kg
unspecified
dally for 5
applications
520 mg/kg
330 mg/kg
TABLE
Acute Toxldty of 1
Regimen
7 hours
7 hours
7 hours
24 hours
single
single
single
single
single
single
twice
single
single
8-4
,2-D1chlorobenzene*
Effects
lethal In 4/5
lowest lethal concentration
eye Irritation, CNS depression,
liver and kidney damage
lowest lethal concentration
100X mortality
weight loss
L050
LD5Q
L050
LD50
lethality
lowest lethal concentration
lowest lethal concentration
Reference
Holllngsworth et al., 1958
Chrlstenson and Fa1rch1ld
1976
•
Holllngsworth et al., 1958
Chrlstenson and Fa1rch1ld
1976
•
Holllngsworth et al., 1958
Holllngsworth et al., 1958
Varshavskaya, 1967a
Varshavskaya, 1967a
Varshavskaya, 1967a
Varshavskaya, 1967a
Rledel, 1941
Chrlstenson and Falrchlld
1976
Chrlstenson and FalrchUd
1976
i
•
*Source: U.S. EPA, 1980c
as
-------
3D
3D
I
TABLE 8-5
Acute ToxIcHy of 1,4-D1chlorobenzene*
Species
Rabbit
Rat
Guinea pig
Guinea pig
Guinea pig
Rabbit
Rat
Rat
Mice
Route
Inhalation
Inhalation
Inhalation
oral
oral
oral
oral
oral
s.c.
Concentration
or Dose
10s mg/m3
10s mg/m3
105 mg/m3
2800 mg/kg
1600 mg/kg
2812 mg/kg
500 mg/kg
4000 mg/kg
5145 mg/kg
Regimen
30 minutes
dally
30 minutes
dally
30 minutes
dally
single
single
single
single
single
Effects
CNS depression, eye
and nose Irritation
CNS depression, eye
and nose Irritation
Irritation, CNS de-
pression, and death
100% lethal
100% survival
LD50
LD50
100% lethal
LD50
Reference
Domenjoz, 1946
Domenjoz, 1946
Domenjoz, 1946
HolUngsworth
et al., 1958
HolUngsworth
et al., 1958
Varshavskaya,
1967a
Chrlstenson and
Fa1rch1ld, 1976
HolUngsworth
et al., 1958
Ir1e et al.,
1973
*Source: Modified from U.S. EPA, 1980c
CNS = Central nervous system; s.c. = subcutaneous
-------
Ir1e et al. (1973) reported the toxldty of 1,4-d1chlorobenzene adminis-
tered subcutaneously to mice. They reported an LD of 5.145 g/kg.
Inhalation of 1,4-d1chlorobenzene (dose not specified) resulted In meta-
chromasla of the nuclei and cytoplasm of liver cells.
The Induction of hepatic porphyrla by oral administration of dlchloro-
benzene has been reported 1n several studies. R1m1ngton and Zlegler (1963)
gave rats 1,2- and 1,4-d1chlorobenzene at levels that Increased over several
days to 455 and 770 mg/kg, respectively. Clinical observations of toxldty
Included anorexia, weakness, clonlc contractions, hepatomegaly and liver
degeneration and focal necrosis. The metabolic alterations seen were
Increased urinary excretion of uroporphyMn, porphoblUnogen and amlnolevu-
I1n1c add (1,4-d1chlorobenzene only). The authors noted that 1,2-d1chloro-
benzene appeared more acutely toxic and damaging to the liver, while 1,4-dl-
chlorobenzene was more porphyrogenlc. Poland et al. (1971) also Induced
hepatk porphyrla 1n rats by the dally administration of 800 mg/kg
1,3-d1chlorobenzene over a 9-day period. Urinary coproporphyrln excretion
Increased 1 day after the first dose, peaked at day 3 and then decreased to
a level 3 times the pre-dos1ng concentration. The Investigators also found
that the administration of 1, 3 or 5 doses of 1,3-d1chlorobenzene enhanced
the metabolism of hexabarbltal and blshydroxycoumarln, and Interpreted these
results to Indicate that l,3-d1chlorobenzene Induced drug-metabolizing
enzymes and enhanced Its own degradation.
Enhancement of xenoblotlc metabolism of the liver by the dlchloroben-
zenes and other halogenated benzenes has been confirmed by other studies.
Ar1yosh1 et al. (1975a) treated female Wlstar rats orally for 3 days with
250 mg/kg/day of each of the dlchlorobenzene Isomers. The activities of
1831A 8-21 03/29/84
-------
several hepatic drug-metabolizing enzymes were Increased by these treat-
ments, although none of the Isomers Increased the liver content of cyto-
chrome P-450. Carlson and Tardlff (1976) also studied the effect of
1,4-d1chlorobenzene and other halogenated benzenes on hepatic metabolism.
Rats orally administered 10-40 mg/kg of the compound for 14 days showed
Increased activity of several metabolic enzymes, glucuronyltransferase and
the detoxification of hexobarbltal and 0-ethyl-0-p-n1trophenyl-phenyl-phos-
phonothloate (EPN).
8.3.2. Subchronlc Toxldty. Many subchronlc toxldty studies of 1,2- and
1,4-d1chlorobenzene have been conducted on the oral and Inhalation routes of
administration. Although the majority of these studies have been on l,4-d1-
chlorobenzene, the available data Indicate that effects similar to those for
1,4-d1chlorobenzene result from exposure to 1,2- and 1,3-d1chlorobenzene.
In the subchronlc Inhalation studies (I.e., those using repeated doses over
a period of weeks or months), the toxic effects noted at low doses (<1000
mg/m3 but >600 mg/m3) were growth depression, Increased liver and kidney
weight and liver necrosis. At higher Inhalation doses (>1000 mg/m3), the
toxic effects were liver, lung and kidney pathology, central nervous system
depression, granulocytopenla and death. The lowest level at which no
adverse effects were found was 580 mg/m3 of 1,4-d1chlorobenzene adminis-
tered via Inhalation to several species for 7 hours/day, 5 days/week, over a
6- to 7-month period (HolUngsworth et al., 1956). Subchronlc toxldty data
for 1,2- and 1,4-d1chlorobenzene are presented 1n Tables 8-6 and 8-7,
respectively.
HolUngsworth et al. (1958) exposed via Inhalation groups of 20 rats, 8
guinea pigs and 2 rabbits of each sex plus 2 female monkeys to repeated
exposures of 560 mg/m3 1,2-d1chlorobenzene for 7 hours/day, 5 days/week
1831A 8-22 03/29/84
-------
CO
to
CD
i
1VJ
03
O
CO
CO
•x
CO
TABLE 8-6
Subchronlc Toxlclty of 1,2-Dlchlorobenzene*
Route Concentration
or Dose
Inhalation 560 mg/m3
290 mg/m»
455 mg/m»
Oral 376 mg/kg (tube)
188 mg/kg (tube)
18.8 mg/kg (tube)
0.01-0.1 rag/kg/day
Regimen
7 hours/day, 5 days/week,
6-7 months
7 hours/day, 5 days/week
6.5 months
dally up to 15 days
5 days/week, 138 doses
5 days/week, 138 doses
5 days/week, 138 doses
5 months
Subject
rat, guinea
pig, rabbit,
monkey
rat, guinea
pig
rat
rat
rat
rat
rat
Effect
Ho effect on several parameters
except decreased spleen weights
1n male guinea pigs
Ho effect on several parameters
Hepatic porphyrla
Liver, kidney weight Increase;
cloudy swelling 1n liver.
Increase In liver and kidney
weight
Ho effects noted
Hematopo1et1c system; altered
Reference
Holllngsworth et al. ,
1958
Holllngsworth et al. ,
1958
Rlmlngton and
Zlegler. 1963
Holllngsworth et al.,
1958
Holllngsworth et al.,
1958
Holllngsworth et al. ,
1958
Varshavskaya, 1967a
500 mg/kg
5 days/week, 13 weeks
rat
250 mg/kg
125 mg/kg
60 mg/kg
30 mg/kg
5 days/week, 13 weeks
5 days/week, 13 weeks
5 days/week, 13 weeks
5 days/week, 13 weeks
rat
rat
rat
rat
conditioned reflexes; Increased
prothromb time and altered
enzyme activities
Increased liver weights; polyuMa HIP, 1982
In males; Increased urinary por-
phyMns; hepatic necrosis and
degeneration; renal tubular
degeneration; thymlc lymphold
depletion; and hematologlc and
clinical changes
Increased liver weights; hema- NTP, 1982
tologlc and clinical changes;
hepatic necrosis
Increased liver weights; hema- NTP, 1982
tologlc and clinical changes;
some hepatic necrosis
Hematologlc and clinical changes NTP, 1982
Hematologlc and clinical changes NTP, 1982
-------
TABLE 8-6 (cont.)
Route Concentration Regimen
or Dose
Oral (cont.) 500 mg/kg 5 days/week, 13 weeks
CD
i
rsj
.*»
Subject Effect
mouse Increased mortality; Increased
liver weights; Increased urinary
and liver porphyrlns; hepatic
necrosis and degeneration; heart
and skeletal muscle lesions;
lymphold depletion of thymus and
spleen
Reference
NTP, 1982
250 mg/kg
30, 60, 125 mg/kg
Subcutaneous unspecified
5 days/week, 13 weeks mouse
5 days/week, 13 weeks mouse
repeated rabbit
Hepatic necrosis and degeneration
1n males; no effects In females
No effects
Blood dyscraslas, (agranulo-
cytosls)
NTP, 1982
NTP, 1982
Ware and West, 1977
*Source: Modlfed from U.S. EPA. 1980c
o
CO
CO
-------
CD
>
TABLE 8-7
Subchronlc ToxUHy of 1,4 -Dichlorobenzene*
Route
Concentration
or Dose
Regimen
Subject
Effect
Reference
Inhalation 105 mg/m3
4800 mg/m»
4600-4800 mg/m'
0.5 hours/day, 5-9 days
8 hours/day, 5 days/week,
up to 69 exposures
8 hours/day, 5 days/week,
rabbit
rat, guinea pig,
rabbit
rabbH
Granulocytopenla; Irritation; CNS
and lung toxldty; death (12/18)
Severe Irritation; CNS depression
and collapse; liver, kidney, lung
pathology; deaths
Tremors, weakness, nystagmus;
some deaths
Zupko and Edwards,
1949
HolUngsworth et al.,
1956
P1ke, 1944
TVS
Oral
o
00
ro
CO
oa
2050 mg/m3
1040 mg/ms
950 mg/m3
900 mg/m3
580 mg/m3
7 hours/day, 5 days/week,
6 months
7 hours/day, 5 days/week,
16 days
7 hours/day, 5 days/week,
157-219 days
8 hours/day, 2 weeks
7 hours/day, 5 days/week,
6-7 months
1000 mg/kg per 92 doses 1n 219 days
dose (tube)
770 mg/kg/day up to 5 days
500 mg/kg/day 5 days/week, 20 doses
(tube)
rat, guinea pig
rat, guinea pig
rat, guinea pig,
rabbit, mouse,
monkey
mouse
rat, guinea pig,
mice, rabbit,
monkey
rabbit
rat
rat
Growth depression, Increased liver,
kidney weight; liver pathology
(necrosis, fatty degeneration,
swelling, flbrosls)
Increased liver, kidney weight
(rat); lung, liver pathology
Growth depression (guinea pig);
Increased liver, kidney weight;
hlstologlcal liver changes
(cloudy swelling, granular
degeneration) 1n rats, no adverse
effects reported 1n rabbit, mouse
or monkey
Respiratory excitation; liver
pathology, deaths; at serum
concentration of 39 mg/l
No adverse effects on several
parameters
CNS depression; weight loss;
liver degeneration and necrosis;
deaths
Hepatic porphyMa
Hepatic centrolobular necrosis;
cloudy swelling, renal tubular
epithelium, and casts
HolHngsworth et al.,
1956
HolUngsworth et al.,
1956
HolUngsworth et al.,
1956
Ir1e et al., 1973
HolUngsworth et al.,
1956
HolUngsworth et al.,
1956
Rlmlngton and Zlegler,
1963
HolUngsworth et al.,
1956
-------
TABLE 8-7 (cont.)
Route
Concentration
or Dose
Regimen
Subject
Effect
Reference
Oral (cont.) 5000 rng/kg diet up to 35 days
oo
i
er>
500 mg/kg/day
(tube)
376 mg/kg/day
5 days/week, 263 doses 1n
367 days
5 days/week, 138 doses In
192 days
250 mg/kg/day 3 days
188 mg/kg/day
20-40 mg/kg/day 2 weeks
Peking duck
rabbit
rat
rat
5 days/week, 138 doses In rat
192 days
rat
18.8 mg/kg/day 5 days/week, 138 doses In rat
192 days
Death In 3/10. Retarded growth
CNS depression; weight loss; liver
pathology
Increased liver and kidney weight;
liver cirrhosis and focal necrosis
Induced liver metabolism enzyme
system
Increased liver and kidney weight
Induced liver metabolism enzyme
system
No adverse effects detected
HolUngsworth et al.,
1956
HolUngsworth et al.,
1956
HolUngsworth et al.,
1956
Ar1yosh1 et al.,
1975a,b
HolUngsworth et al.,
1956
Carlson and Tardlff.
1976
HolUngsworth et al.,
1956
•Source: U.S. EPA. 1980c
10
OD
-P.
-------
for periods ranging up to 7 months. They reported that this exposure
regimen did not result 1n any adverse effects on any of the animal species
tested. Inhalation-exposed groups of 20 rats and 8 guinea pigs of each sex
plus 10 female mice to repeated exposures of 290 mg/m3 1,2-d1chlorobenzene
for 7 hours/day, 5 days/week, for 6.5 months again resulted 1n no adverse
effects on any of the tested animals.
Several species of laboratory animals were exposed to 1,4-d1chloroben-
zene vapor at each of five concentrations for 7 hours/day {8 for the highest
dose group), 5 days/week (Holllngsworth et al., 1956). Effects In animals
(rats, guinea pigs, rabbits) exposed to 4800 mg/m3 for up to 69 exposures
Included: some deaths (up to 25%); marked tremors, weakness, collapse, eye
Irritation, and reversible eyeground changes 1n rabbits, but no lens
changes; weight loss, liver degeneration and necrosis, cloudy swelling of
renal tubular epithelium (rats); and lung congestion and emphysema
(rabbits). Effects 1n rats and guinea pigs exposed at 2050 mg/m3 for 6
months Included: growth depression (male guinea pigs); Increased liver and
kidney weights (male rats); and liver pathology (cloudy welling, fatty
degeneration, focal necrosis, cirrhosis) 1n some of the animals. Effects In
animals exposed for as high as 12 exposure over 16 days at 1040 mg/m3
were: Increased liver, spleen and kidney weights (guinea pigs); pulmonary
edema, congestion, hemorrhage; hepatic centrolobular congestion and granular
degeneration (rats). Effects 1n animals exposed to 950 mg/m3 for 157-219
days Included: growth depression (guinea pigs); Increased liver weights
(rats, guinea pigs) and Increased kidney weights (rats); and centrolobular
hepatocellular cloudy swelling or granular degeneration (rats). No adverse
effects were observed 1n rats, guinea pigs, rabbits, mice or a monkey
exposed at 580 mg/m3 for 6-7 months.
1831A 8-27 03/29/84
-------
In the corresponding subchronlc oral studies, female rats (10/group,
strain not specified) were dosed via stomach tube with 18.8, 188 or 376 mg
l,2-d1chlorobenzene/kg/day, 5 days/week, for a total of 138 doses over 192
days (50% 1,2-d1chlorobenzene 1n olive oil) (Holllngsworth et al., 1958).
No adverse effects on growth or mortality were observed at any dose level.
A dose of 376 mg/kg/day resulted 1n slightly Increased liver and kidney wet
weights, a slight decrease 1n spleen wet weight and slight to moderate
cloudy swelling 1n the liver. Slight Increases 1n liver and kidney wet
weights were observed at the Intermediate dose and no effects were noted at
the lowest dose (18.8 mg/kg/day). Application of 1,2-d1chlorobenzene to the
eyes of two rabbits resulted 1n slight to moderate pain and slight conjunc-
tlval Irritation which cleared completely within 7 days.
l,4-D1chlorobenzene was dissolved 1n olive oil and given by stomach tube
to male adult rats (2/group) at 10, 100 or 500 mg/kg 5 days/week for 4
weeks. Centrolobular hepatic necrosis and marked cloudy swelling of renal
tubular epithelium with cast formation occurred 1n animals given 500 mg/kg.
No adverse effects were observed at the lower dose levels (Holllngsworth et
al., 1956).
White female rats (10/group) were fed either 18.8, 188 or 376 mg/kg of
l,4-d1chlorobenzene 1n olive oil (emulsified with acacia) by stomach tube 5
days/week for a total of 138 doses 1n 192 days (Holllngsworth et al., 1956).
At the highest dosage level of 376 mg/kg/dose, Increased liver and kidney
weights, and slight hepatic cirrhosis and focal necrosis were observed. No
adverse effects were noted at the lowest dose level (18.8 mg/kg). No cata-
racts were observed 1n these exposures. The same Investigators fed rabbits
(5/group) with 1,4-d1chlorobenzene 1n olive oil by Intubation for up to 92
doses 1n 219 days at a level of 1000 mg/kg/dose. Another group received a
1831A 8-28 03/29/84
-------
dose level of 500 mg/kg/dose 5 days/week for a total of 263 doses In 367
days. Effects at the higher dose level (1000 mg/kg) Included: weight loss,
tremors, weakness, hepatic cloudy swelling and a few areas of focal
necrosis, and deaths. Similar changes, but no deaths, were noted 1n rabbits
on the lower dose regimen. No cataracts were observed. Peking ducks
(10/group) fed 1,4-d1chlorobenzene 1n their diet at 0.5% (5000 mg/kg diet)
for 35 days experienced retarded growth and 30% mortality in 28 days, but no
cataracts were observed (HolUngsworth et al., 1956).
Varashavskaya (1967) administered 1,2-d1chlorobenzene 1n sunflower oil
orally to rats at doses of 0.001, 0.01 and 0.1 mg/kg/day over a 5-month
period. At the highest dose level, Inhibition of erythropolesls and bone
marrow activity was observed. In addition, at this level, adrenal weight
and ascorbic add content decreased, serum alkaline phosphatase and trans-
amlnase activity Increased, and serum glutathlone decreased. Similar
effects were noted 1n the Intermediate dose level animals, but not at the
lowest dose. These results are 1n distinct contrast to those of HolUngs-
worth et al. (1956) who found no effects at a dose level of 18.8 mg/kg after
a 6-month administration period.
Subchronlc toxldty studies on 1,2-d1chlorobenzene were conducted under
the auspices of the National Toxicology Program (NTP, 1982). The Investiga-
tions were conducted using 10 male and 10 female B6C3F mice and 10 male
and 10 female F344/N rats. The 1,2-d1chlorobenzene was administered by
gavage using a corn oil vehicle, 5 ma/kg, 5 days/week for 13 weeks. The
1,2-d1chlorobenzene doses used were 0, 30, 60, 125, 250 or 500 mg/kg.
Ihe 1,2-d1chlorobenzene mouse study resulted 1n a decreased survival
rate In the male 250 mg/kg dose group with a mortality rate of 10% (1/10)
and 1n the male and female 500 mg/kg dose groups with mortality rates of 40%
1831A 8-29 03/29/84
-------
(4/10) and 30% (3/10), respectively (NTP, 1982). Liver weight/body weight
ratios were significantly Increased 1n both males and females at 500 mg/kg.
Spleen weight/body weight ratios were decreased 1n all 1,2-d1chlorobenzene
dosed female groups and uterus weight/body weight ratios were decreased In
the 500 mg/kg female group. No biologically significant changes were found
during the hematologlcal evaluations. Female mice receiving 500 mg/kg
1,2-d1chlorobenzene were found to excrete 6 times more coproporphyrlns 1n
their urine and had a 2-fold Increase 1n liver porphyrln concentrations when
compared with control mice. No hlstologlcal effects were observed In the 0,
30, 60 or 125 mg/kg dose groups. The 250 mg/kg dose male mice group was
found to have hepatocellular necrosis and degeneration while the females
receiving this dose were found to be unaffected. Ninety percent of both the
male and female 500 mg/kg dose groups were observed with centrllobular
necrosis, necrosis of Individual hepatocytes or hepatocellular degeneration.
The hearts of the 500 mg/kg dosed animals had mineralization of the myo-
cardlal fibers (multiple foci) and the skeletal muscles were observed with
some necrosis, myosltls and mineralization. Both the male and female 500
mg/kg groups were observed with lymphold depletion of the thymus and spleen
and a yellow-green pigmentation (considered to be hemoslderln) In some of
their livers. Based on these results NOELs are determined to be 125 mg/kg
for male mice and 250 mg/kg for female mice.
The 1,2-d1chlorobenzene rat study resulted 1n a dose-dependent depres-
sion In mean body weight gains over the 13-week period (NTP, 1982). A dose-
related Increase 1n liver weights was also observed 1n both sexes with
significant Increases 1n liver weight/body weight ratios 1n the 125, 250 and
500 mg/kg male and female dose groups. Decreases In spleen and thymus
1831A 8-30 03/01/84
-------
weights and organ weight/body weight ratios were observed 1n the male 500
mg/kg group. Minimal changes 1n hematologlc parameters were observed 1n the
500 mg/kg dose groups. An Increased number of platelets were found 1n
female rats receiving 60, 125 and 500 mg/kg doses of 1,2-d1chlorobenzene. A
dose-related Increase 1n serum cholesterol levels were found 1n males
receiving 30, 125, 250 and 500 mg/kg and 1n females receiving 125-500 mg/kg.
A decrease 1n serum trlglycerldes was observed at 500 mg/kg (males) and 250
mg/kg (females), and a dose-related Increase 1n total serum protein was
observed at 250-500 mg/kg (males) and at 30-500 mg/kg (females). Female
rats were observed with minimal Increases 1n serum glucose levels at l,2-d1-
chlorobenzene doses of 30, 125, 250 and 500 mg/kg. PolyuMa was observed 1n
males receiving the 500 mg/kg dose. A 3- to 5-fold Increase In urinary uro-
porphyrlns and coproporphyrlns were seen 1n males and females at 500 mg/kg.
The liver porphyMn levels were not altered by 1,2-d1chlorobenzene at any
dose level. Hepatocellular necrosis and focal hepatic necrosis were
observed 1n some of the rats at the 125 mg/kg dose. More hepatocellular
necrosis was seen 1n both males and females at 250 mg/kg. Most of the rats
1n the 500 mg/kg dose groups had liver lesions, either centrllobular
degeneration or hepatic necrosis. The 500 mg/kg male group also had renal
tubular degeneration and thymlc lymphold depletion. A yellow-green to gold
pigment (believed to be hemoslderln) was also observed 1n the livers of rats
at 250 and 500 mg/kg. Based on these results, a LOAEL for 1,2-d1chloroben-
zene 1n rats 1s determined to be 30 mg/kg.
The effect of subchronlc treatment with 1,4-d1chlorobenzene has been
extensively Investigated 1n guinea pigs (Salamone and Coppola, 1960; Totaro,
1961; Coppola et al., 1963; Totaro and L1car1, 1964). Intramuscular Injec-
tions of 125 mg 1,4-d1chlorobenzene (50X 1n almond oil) dally for 20 days
1831A 8-31 03/15/84
-------
were found to produce weight loss (5-10%), Increased blood serum trans-
amlnase and Increased clotting times.
8.3.3. Chronic ToxIcUy. Two-year chronic bloassay studies using l,2-d1-
chlorobenzene were conducted under the auspices of the National Toxicology
Program (NTP, 1982). The Investigations were conducted using 50 male and 50
female B6C3F1 mice and 50 male and 50 female F344/N rats. 1,2-D1chloroben-
zene was administered by gavage 1n a corn oil vehicle, 5 ml/kg, 5
days/week for 103 weeks. The dosage groups used were 0 (vehicle control),
60 and 120 mg/kg.
The 1,2-d1chlorobenzene mouse study resulted 1n a 105-week (exposure
duration 103 weeks) survival rate of 52% (26/50), 64% (32/50) and 70%
(35/50) 1n male mice and 66% (33/50), 80% (40/50) and 76% (38/50) In female
mice for the 0, 60 and 120 mg/kg dose groups, respectively (NTP, 1982).
Mean body weights were comparable between 1,2-d1chlorobenzene dosed and
control male mice but the female dosed mice were slightly higher 1n body
weight than controls. Hlstologlcal findings of neoplasms 1n dosed and
control groups will be discussed 1n Section 8.3.5. Carc1nogen1c1ty. No
apparent Increase 1n non-neoplast1c lesions In the liver, kidney, bone
marrow, spleen or other organs of male and female mice were observed as a
result of administration of 1,2-d1chlorobenzene over the 105-week study
period.
The l,2-d1chlorobenzene rat study resulted 1n 104-105 week (exposure
duration 103 weeks) survival rates of 84% (42/50), 72% (36/50) and 38%
(19/50) [significantly different from the 60 mg/kg group (p=0.014) and 0
mg/kg group (p<0.001)] 1n male rats and 62% (31/50), 66% (33/50) and 64%
(32/50) 1n female rats for the 0, 60 and 120 mg/kg dose groups, respectively
(NTP, 1982). Slightly lower mean body weights were observed 1n the male 120
1831A 8-32 03/29/84
-------
mg/kg group when compared with the 0 and 60 mg/kg male groups. This was
contrasted by higher mean body weights 1n the female animals In the 120
mg/kg group when compared with the female controls. H1stolog1cal findings
of neoplasms 1n dosed and control groups will be discussed 1n Section 8.3.5.
CardnogenlcUy. No apparent Increase 1n non neoplastlc lesions 1n the
liver, kidney, bone marrow, spleen, thymus or other organs of male and
female rats were observed as a result of administration of 1,2-d1chloro»
benzene over the 105-week study period.
8.3.4. MutagenlcUy. The capability of the dlchlorobenzenes to Induce
mutations or other alterations of genetic structure has not been extensively
Investigated, although a recent study (Zapata-Gayon et al., 1982) Indicates
such research 1s warranted. As cited 1n Section 8.2., a higher Incidence of
chromosomal breaks was observed 1n the leukocytes of humans accidentally
exposed for a short period of time to 1,2-d1chlorobenzene vapors (Zapata-
Gayon et al., 1982).
Anderson et al. (1972) reported that 1,2-d1chlorobenzene did not Induce
point mutations when tested 1n Salmonella typhlmuMum (8 unspecified
strains) without activation. No conclusions can be drawn from this study
because of the lack of details provided and because metabolic activation was
not used. In an abstract, Lawlor et al. (1979) evaluated the ability of
chlorinated phenols, benzenes and hexanes to Induce mutations or DNA damage
1n bacteria. Tests of 1,2- and 1,4-d1chlorobenzene (doses not specified)
were negative 1n five strains of Salmonella (TA98, TA100, TA1535, TA1537 and
TA1538) with and without rat liver mlcrosomal activation. DNA repair tests
with two Salmonella and two E. coll strains with and without activation
Indicated the ability of two unspecified chlorobenzenes to cause preferen-
tial killing of the DNA repair deficient strains. Because these results
1831A 8-33 03/29/84
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were reported In an abstract with Insufficient experimental detail, the
results cannot be critically evaluated. These negative findings In bacteria
were supported by studies conducted for the National Toxicology Program
(Appendix M of NTP, 1982). In these studies, 1,2-d1chlorobenzene was
negative 1n four Salmonella strains {TA98, TA100, TA1535 and TA1537) when
tested with and without metabolic activation at doses as high as 1300
vg/plate.
Prasad and Pramer (1968) reported testing all three Isomers of dlchloro-
benzene 1n an auxotrophlc strain of Asperglllus nldulans, a soil mold. All
three compounds Increased the frequency of back mutations 1n the following
descending order: 1,4-, 1,3- and 1,2-d1chlorobenzene. Abnormal numbers of
chromosomes and abnormally shaped nuclei were observed 1n the root cells of
AlHum exposed for 4 hours to 1,4-d1chlorobenzene vapors (Carey and
McDonough, 1943). Sharma and Bhattacharyya (1956) reported chromosomal
breakage and nondlsjunctlon 1n the root tips and flower buds of Nothoscordum
fragans, which were treated with saturated aqueous solutions of 1,4-d1chlo-
robenzene. Various mltotlc abnormalities were also found 1n the somatic
cells and chromosomes of the root tips of several plant species treated with
1,4-d1chlorobenzene (SMvastava, 1966). The aberrations Included shortening
and thickening of chromosomes, early separation of chromatlds, tetraplold
cells, blnucleate cells, chromosome bridges and chromosome breaks In the
heterochromatlc regions. Sarbhoy (1980) exposed germinating root tips of
Lens esculenta to 1,4-d1chlorobenzene vapors and also observed chromosome
fragmentation, condensation and bridges and polyplold cells.
8.3.5. Cardnogenldty. The National Toxicology Program (NTP) conducted
a 2-year study on 1,2-d1chlorobenzene with F344/N rats and with B6C3F
mice (NTP, 1983). There were 50 animals of each sex for each dosage group
1831A 8-34 03/29/84
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1n both the rat and mouse studies. The 1,2-d1chlorobenzene was prepared 1n
corn oil and administered by gavage 5 days/week for 103 weeks. The dosages
used were 0, 60 and 120 mg/kg for each day of dosing. The 1,2-dlchloro-
benzene was >99% pure with the major Impurity found to be 0.84% v/v of
l,4-d1chlorobenzene. The stability of the 1,2-d1chlorobenzene preparation
was monitored.
8.3.5.1. RATS -- In male rats survival was reported (NTP, 1983a) to
be significantly reduced 1n the 120 mg/kg group. The NTP peer review
committee for this draft document (NTP, 1983a) suggested that the reduced
mortality of this group of animals provides evidence that the MTD had been
reached. However, this group had 12 animals which died before the end of
the study with gavage solution In the lungs and another 5 that were killed
as a result of accident 1n the gavage procedure. If these 17 accidentally
Injured or killed animals had survived there would have been comparable sur-
vival 1n this test group to the low dose and control groups. The mortality
of the males 1n this group 1s, therefore, a function of technical problems
with the gavage technique and does not reflect a compound related response.
Therefore, the conclusion can be drawn that the reduced survival of these
animals does not provide evidence that the maximum tolerated dose had been
reached. Body weights of rats 1n the treated groups were within 1% of those
of the controls among males and 12 and 11% higher than controls for female
rats 1n the low and high dose groups respectively after 99 weeks.
The results of the h1stopatholog1cal analysis showed that non-neoplast1c
lesions were not significantly Increased 1n the treated rats nor were neo-
plasms other than adrenal pheochromocytoma. The latter (Table 8-8) was
significantly Increased In the low dose group when compared to controls by
the life table test but not In the other statistical tests. The terminal
1831A 8-35 04/16/84
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TABLE 8-8
NTP Bloassay of l,2-D1chlorobenzene
Analysis of Primary Tumors 1n Male Rats: Adrenal Pheochromocytomas*
Vehicle 60 mg/kg 120 mg/kg
Control
Tumor Rates
Overall 9/50 (18%) 16/50 (32%) 6/49 (12%)
Adjusted 20.9% 40.5% 21.7%
Terminal 8/42 (19%) 13/36 (36%) 2/18 (11%)
Statistical Tests
Life Table p = 0.201 p = 0.039 p = 0.380
Incidental Tumor Test p = 0.499 N p = 0.070 p = 0.420 N
Cochran-Armltage Trend, p = 0.285 N p = 0.083 p = 0.303 N
Fisher Exact Tests
*Source: NTP, 1982
1831A 8-36 04/16/84
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Incidence of adrenal pheochromocytoma 1n males was 36% (13/36) 1n the low
dose group compared with 19% (8/42) 1n controls. The historical Incidence
of adrenal tumors 1n male F344/N rats receiving corn oil by gavage, based on
data from seven different laboratories Is 153/986 (15.5%).
In rats, therefore, under conditions of this test, cardnogenlclty was
not 1n evidence. However, based on the following observations from the
2-year study, a larger dose probably could have been tolerated:
1) there was no Increase 1n mortality 1n treated groups when com-
pared with controls,
2) there was no loss of weight 1n the treated groups compared to
the controls,
3) there was no evidence of life-threatening pathology 1n the
treated groups compared to the controls.
The question 1s then raised as to whether a higher dose could, or should,
have been tested. In the 13-week dose selection study rats were given doses
of 60, 125, 250, 500 and 1000 mg/kg on each day of dosing and no deaths
occurred at any dose up to and Including 500 mg/kg In both male and female
rats. Weight gain was within 7% of the controls 1n female rats through the
500 mg/kg group and through the 250 mg/kg group 1n male rats. Mortality and
weight decrement have been traditionally used as Indicators of levels of
toxldty which would be expected to reduce the number of animals at risk 1n
a long-term study and, hence, Indicate when Inappropriately high doses were
being used. Use of these criteria Indicates that a dose over 120 mg/kg
could have been used 1n the 2-year study.
Another consideration \n the design of this study Is that of the pharma-
coklnetlcs of 1,2-d1chlorobenzene. Azouz et al. (1955) studied the metabo-
lism and excretion of both 1,2-d1chlorobenzene and 1,4-d1chlorobenzene 1n
rabbits given 500 mg/kg. They found that 1,2-d1chlorobenzene took 5-6 days
1831A 8-37 03/29/84
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for complete metabolism and elimination. Klmura et al. (1979) found similar
results with oral administration of 200-800 mg/kg 1,4-d1chlorobenzene 1n
VMstar rats. A regimen which gives 120 mg/kg for only 5 days, followed by
no treatment for 2 days, may not be providing effective continuous exposure,
an element Important 1n the chronic toxldty testing rationale.
In summary, the assay of l,2-d1chlorobenzene 1n F344 rats did not give
evidence of cardnogenldty. However higher doses probably could have been
tolerated and the assay was not as sensitive as 1t could have been.
8.3.5.2. MICE — In B6C3F mice 500 mg/kg for each day given 1n the
13-week study resulted 1n Increased mortality and significant weight decre-
ment (47X 1n males and 67% 1n females). Only 1 male animal died at the 250
mg/kg dose at 13 weeks. Hlstopathology of the liver, myocardium, skeletal
muscle, thymus and spleen were found at 500 mg/kg but the only compound-
related lesion at the 250 mg/kg dose was found In males; necrosis of Indi-
vidual hepatocytes (2/10), hepatocellular degeneration (1/10) and pigment
deposition (1/10). No compound related lesions were found 1n females at
this dose. At the 250 mg/kg dose, the body weights did not different
significantly from controls 1n this 13-week study. Some liver pathology was
observed In male mice (4/10) that received a dose of 250 mg/kg 1n this
13-week study. The question of whether this level of pathology, In a poten-
tial target organ, 1s sufficient justification for selecting 120 mg/kg as
the highest dose 1n the 2-year study must be raised. As 1n the chronic
study with rats there were no significant weight or survival differences
between treated and control groups.
After hlstopathologlcal analysis the only non-neoplast1c lesion which
appeared to be treatment-related was a dose-related trend 1n tubular regen-
eration of the kidney 1n male mice. Increases 1n non-neoplast1c lesions of
1831A 8-38 04/16/84
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the liver were not found. In fact there was a dose related decrease 1n
hepatocellular adenoma Incidence and a significant decrease 1n this tumor
when the highest dose group and controls were compared. It should be noted
that male B6C3F1 mice had an Incidence of 38X (19/50) of liver adenoma or
carcinoma 1n the control group. The problem of a high background Incidence
of this type 1n mice 1s repeatedly at Issue 1n terms of suitability of these
animals for testing when liver tumors are the potential target lesions.
In conclusion, neither the rat nor the mouse study gave evidence of
cardnogenldty under the test conditions, but the doses selected were prob-
ably below the MTD 1n both species, reducing the sensitivity of the assays.
The marginal Increase 1n adrenal pheochromocytoma 1n rats should be noted as
this lesion appears with hexachlorobenzene, also at a relatively low dose.
If the IARC criteria for classifying carcinogens were used, this evidence 1s
clearly Inadequate for developing any conclusions concerning the cardno-
genldty of 1,2-d1chlorobenzene 1n humans.
8.3.6. Reproductive and Teratogenlc Toxldty. No data on the reproduc-
tive and teratogenlc toxldty of the dlchlorobenzenes were available for
review; however, dlchlorobenzenes have been demonstrated to cross the
placenta (Dowty and Laslter, 1976).
8.4. INTERACTIONS
As Indicated 1n Section 8.2., halogenated benzenes, Including the
dlchlorobenzenes, have the ability to Induce hepatic xenoblotlc metabolizing
enzymes (Ar1yosh1 et al., 1975a,b; Carlson and Tardlff, 1976; Carlson,
1977). This type of Induction theoretically will alter the metabolism of
other compounds; thus, the toxldty resulting from the concurrent exposure
to the dlchlorobenzenes and other compounds may be different from the expo-
sure to the Individual chemicals. One study was available that Investigated
1831A 8-39 03/29/84
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the effect of dlchlorobenzene on the toxldty of other compounds (Townsend
and Carlson, 1981). Mice were orally administered 0.1 mmol/kg (18 mg/kg bw)
of 1,4-d1chlorobenzene and other chlorinated and bromlnated benzenes dally
for 7 days, after which the mice were used In the determination of LD
values for four organophosphorus Insecticides. The treatment with l,4-d1-
chlorobenzene was found to decrease the lethality of parathlon and paraoxon
by -50%, although other compounds were much more effective. In addition,
Carlson and Tardlff (1976) observed that administration of 1,4-d1chloroben-
zene (10-40 mg/kg for 14 days to rats) enhanced the detoxification of hexo-
barbltal and EPN.
Harden and Baetjer (1978) reported a human case of aplastlc anemia
following exposure to 1,4-d1chlorobenzene and naphthalene. While a single
case report cannot be considered convincing evidence for an Interactive
effect, the possibility of Interactions cannot be dismissed.
8.5. SUMMARY
The available data on the pharmacoklnetlcs of the dlchlorobenzenes
Indicate that these compounds are absorbed through the lungs, skin and
gastrointestinal tract and rapidly distributed to many tissues, especially
those with a high I1p1d content. Metabolism 1s accomplished by oxidation to
dlchlorophenols which are conjugated as glucuronldes and sulfates. Elimina-
tion, primarily through the urine, appears to be rapid, although the data
are Insufficient to make quantitative estimates of the rate. Biliary excre-
tion does occur but little of the biliary excreted dlchlorobenzene has been
found In the feces, probably due to enterohepatlc redrculatlon. The
dlchlorobenzenes, as well as the other chlorinated benzenes, are capable of
bloaccumulatlon (see Section 5.3.).
1831A 8-40 03/29/84
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Data on possible effects In humans were available In a number of case
reports and 1n a single ep1dem1olog1c study. The case studies demonstrate
the ability of the dlchlorobenzenes to be absorbed through the lungs and gut
and their acute and subchronlc toxlclty. Many of these reports. In which
exposure may have occurred over several years, noted toxic effects 1n the
blood, such as chronic lymphold leukemia and anemia, as well as effects on
the liver. Ihe one available occupational study reported chromosomal
alterations In leukocytes resulting from a short-term exposure to
l,4-d1chlorobenzene. laken together, these studies suggest a possible toxic
action of dlchlorobenzenes on bone marrow and other organs of the blood-
forming system.
Studies of the acute and subchronlc toxlclty of the dlchlorobenzene
Isomers Indicate that, In general, these compounds have similar target
organs and effects. At oral doses ranging from 125-1000 mg/kg over periods
of up to 6 months, the dlchlorobenzenes cause central nervous system depres-
sion, Injury to liver, kidney, heart, thymus and spleen, and hepatic and
urinary porphyrla; however, one study reported that a low dose of 0.01 mg/kg
over a 5-month period Inhibited erythropolesls and bone marrow activity.
The subchronlc oral toxlclty studies In rats provide two estimates of NOEL
values: 0.001 mg/kg (Varashavskaya, 1967) for 1,4-d1chlorobenzene and 18.8
mg/kg for 1,2- and for 1,4-dlchlorobenzene (Holllngsworth et al., 1956,
1958). The NTP (1982) subchronlc oral study on 1,2-d1chlorobenzene 1n mice
provided higher estimated NOEL values of 125 and 250 mg/kg for males and
females, respectively. A 2-year NTP chronic oral gavage study on l,2-d1-
chlorobenzene In rats and mice, conducted primarily as a carclnogenesls
bloassay at the 60 and 120 mg/kg dose levels, resulted 1n only Increased
mortality In the male rats given 120 mg/kg. Acute and subchronlc Inhalation
1831A 8-41 03/01/84
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studies of dlchlorobenzenes Indicate similar toxic effects and target organs
as seen In the oral studies. The effects occurred at doses >950 mg/m3;
Inhalation NOELs were reported as 580 mg/m3 for 1,2-d1chlorobenzene
(HolUngsworth et a!., 1956) and 290 mg/m3 for 1,4-d1chlorobenzene
(Holllngsworth et al., 1958).
The mutagenlclty studies with bacteria were lacking In experimental
detail, but suggest that the dlchlorobenzenes are probably not mutagenlc 1n
bacteria. However, several studies with mold and plant cultures treated
with dlchlorobenzenes have reported mutations and chromosomal aberrations.
Because chromosomal aberrations were also observed In human workers exposed
to 1,2-dlchlorobenzene, the weight of available evidence suggests that the
dlchlorobenzenes are clastogens. The carcinogenic activity of one Isomer,
1,2-dlchlorobenzene, was tested In the NTP bloassay program In two rodent
species at doses of 60 and 120 mg/kg. No evidence of carcinogenic activity
was found under the test conditions.
1831A 8-42 03/01/84
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9. TRICHLOROBENZENES
The trlchlorobenzenes are produced 1n relatively small amounts (1.3-3.95
million kg/year 1s the estimated 1983 production) (U.S. EPA, 1983) and are
used primarily as chemical Intermediates, solvents, Insecticides, and cool-
ants and Insulators 1n electrical equipment (Hawley, 1977; SUmak et a!.,
1980). Trlchlorobenzenes have been detected 1n all environmental media
Including drinking water (see Section 4.3.), and have been found to bloaccu-
mulate 1n fish (see Section 5.3.). In addition to the exposure of humans
during the manufacture and use of trlchlorobenzenes, exposure 1s likely to
result from Inhalation and 1ngest1on of contaminated air and water.
9.1. PHARMACOKINETICS
9.1.1. Absorption. No quantitative studies on the absorption of the trl-
chlorobenzenes from the gastrointestinal tract, skin or lungs were found.
Information on absorption may be obtained from data describing elimination.
Male Charles River rats (16 1n the group) excreted a mean of 84%, and two
female rhesus monkeys excreted a mean of 40% of the orally (by gavage)
administered dose of 10 mg 14C-1,2,4-tr1chlorobenzene/kg 1n the 24-hour
urine, while fecal elimination accounted for only 11 and IX, respectively
(L1ngg et al., 1982). The results Indicate that 1n these species, this
Isomer 1s well absorbed through the gastrointestinal tract. Two Chinchilla
female rabbits given doses of 500 mg 1,3,5-tr1chlorobenzene/kg 1n arachls
oil by gavage expired -10% of the administered dose from the lungs 1n 9 days
(Parke and Williams, 1960). These Investigators also observed elimination
of urinary and fecal metabolites, but quantities or percentages were not
reported.
That the trlchlorobenzenes are absorbed by the respiratory tract and by
the skin can be Inferred from toxldty studies using the Inhalation (Kodba
1832A 9-1 03/29/84
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et al., 1981) and dermal (Brown et al., 1969) routes of exposure. These
studies, however, were not designed to give Information on rates of
absorption.
9.1,8. Distribution. Smith and Carlson (1980) examined the distribution
of 14C-1,2,4-tr1chlorobenzene 1n groups of four male Sprague-Dawley rats
on days 1, 6, 11 and 16 after oral dally dosing with 181.5 mg/kg (1 mmol/kg)
for 7 days. Their data Indicate that the adrenals Initially had the highest
concentration of radlolabel. This level declined rapidly; however, by day
11 1t was less than twice the background of the other tissues. Abdominal
fat had the highest concentration at the end of 1 day (Table 9-1) and main-
tained detectable concentrations (20% of the day 1 level) for the duration
of the observation period (16 days). The liver also maintained detectable
levels throughout the recovery period, retaining -30% of the day 1 level by
day 16. These authors also found that starvation for 4 days had no observed
effect on the distribution of l4C-tr1chlorobenzene 1n fat or liver.
Parke and Williams (1960) reported the distribution of 1,3,5-tMchloro-
benzene 1n one rabbit on day 8 following oral administration of 500 mg/kg as
follows: 13% of the administered dose was detected In the feces, 23% (4% as
monochlorobenzene) 1n the gut, 5% 1n the pelt, 5% In depot fat (exclusive of
pelt) and 22% 1n the carcass.
9.1.3. Metabolism. No metabolic studies following the Inhalation of tr1-
chlorobenzenes were available for review, but the metabolic fate following
oral and/or Intravenous (1.v.) or 1ntraper1toneal (1.p.) administration has
been characterized 1n rabbits (Jondorf et al., 1955; Parke and Williams,
1960; Kohll et al., 1976) and 1n rats and monkeys (L1ngg et al., 1982).
Jondorf et al. (1955), using spectrophotometrlc analysis, studied the
metabolism of all three Isomers of trlchlorobenzene 1n groups of 3 or 4
1832A 9-2 03/29/84
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TABLE 9-1
Distribution of 14C-Labeled 1,2,4-Tr1chlorobenzene 1n Rat Tissues
after Oral Dosing with 181.5 mg/kg/day for 7 Days3
Tissue
Abdominal fat
Liver
Adrenals0
Muscle
Kidney
Heart
Spleen
Activity (dpm/g t1ssue)b
Day 1 Day 6 Day 11
2033+439 642+54 342+10
1075+87 442i22 308+21
754+J32 246+22 d/
400+30 d/
1471+167 404+43 d/
438il 4 d/
404+14 d/
Day 16
408+39
317+18
aSource: Smith and Carlson, 1980
value 1s the mean +^ SE for 4 rats, except for abdominal fat on day 1,
which was for three rats.
cTotal for both adrenals; they were not weighed.
less than twice background; further analyses were not performed.
1832A
9-3
03/29/84
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Chinchilla rabbits given oral doses of 500 mg/kg. The results Indicated
that the 1,2,3- Isomer was metabolized to 2,3,4-trlchlorophenol (TCP), to
3,4,5-TCP to a lesser degree, and to small amounts of 3,4,5-tMchlorocate-
chol. During the 5 days after administration, 50% of the dose was excreted
1n the urine as glucuronlc add conjugates, 12% as sulfurlc add (sulfate)
conjugates and 0.3% as 2,3,4-tr1chlorophenylmercaptur1c add. The 5-day
urinary metabolites of 1,2,4-tr1chlorobenzene were represented by glucuron-
1de conjugates (27%), sulfurlc add conjugates (11%) and 2,3,5- and 2,4,5-
trlchlorophenylmercapturlc add (0.3%). The major phenols formed were
2,4,5- and 2,3,5-TCP. For the 1,3,5- Isomer, 20X was excreted as glucuron-
1de and 3% as sulfurlc acid conjugates. No mercaptudc add was found,
2,4,6-trlchlorophenol was the only phenol detected 1n the urine, and some
unchanged 1,3,5-tr1chlorobenzene was present 1n the feces. To further char-
acterize and clarify the metabolic fate of the 1,3,5- Isomer, Parke and
Williams (1960) followed the 9-day urinary excretion 1n 2 or 3 female Chin-
chilla rabbits treated orally with 500 mg of the 1somer/kg. For the first 3
days, the rabbits eliminated 2,4,6-TCP along with some minor monochloro-
phenols, while from day 4 to 9, 4-chlorophenol was detected more prominently
along with 2,4,6-TCP and -1% of the dose as 4-chlorocatechol.
Using GC-MS analysis, Kohll et al. (1976) examined the metabolism of the
three trlchlorobenzene Isomers following 1.p. Injection of 60-75 mg/kg doses
1n vegetable oil to male rabbits (number and strain not reported). In
agreement with the results of Jondorf et al. (1955), the major urinary
metabolites of 1,2,4-tr1chlorobenzene were 2,4,5- and 2,3,5-TCP. The major
metabolite of 1,2,3-tr1chlorobenzene was 2,3,4-TCP, with 2,3,6- and 3,4,5-
TCP as minor urinary metabolites. The 1,3,5- Isomer was metabolized to
1832A 9-4 03/29/84
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2,3,5- and 2,4,6-TCP and a third, more polar metabolite, was tentatively
Identified as a dlchlorobenzene with 2 hydroxyl and 1 methoxyl substltuents.
L1ngg et al. (1982) Investigated the metabolism of 1,2,4-tr1chloroben-
zene 1n groups of 16 male Charles River rats and groups of 2 female rhesus
monkeys following oral or 1.v. administration of 10 mg/kg doses and found
similar phenolic metabolites to those observed 1n the rabbit. These
researchers were also able to characterize some species specific conju-
gates. An 1somer1c pair of 3,4,6-tr1chloro-3,5-cyclohexad1ene-l,2-dlol
glucuronldes accounted for 48-61% of the 24-hour urinary metabolites 1n the
monkeys. Also found were glucuronldes of 2,4,5- and 2,3,5-TCP and unconju-
gated TCP, which accounted for 14-37 and 1-37% of the urinary metabolites,
respectively. In the rat, the 2,4,5- and 2,3,5- Isomers of N-acetyl-S-(tr1-
chlorophenyl)-L-cyste1ne accounted for 60-62% of the urinary metabolites.
Minor urinary metabolites Included 2,4,5- and 2,3,5-tr1chloroth1ophenol and
free 2,3,5- and 2,3,4-TCP, which accounted for 28-33 and 1-10% of the mater-
ial excreted, respectively.
On the basis of the studies of L1ngg et al. (1982) and Kohll et al.
(1976), 1t 1s apparent that there may be differences among species 1n the
metabolism of 1,2,4-tr1chlorobenzene. It seems likely that these differ-
ences will extend to the other Isomers of trlchlorobenzene as well. Both
reports postulated the same first step 1n metabolism (I.e., Initial forma-
tion of arene oxide Intermediates), but Indicated differences 1n the subse-
quent metabolic reactions. In the rat, conjugation of the Intermediate with
glutathlone was postulated to account for the sulfur-containing urinary
metabolites. In the monkey, hydrolysis of the arene oxide to the dlhydro-
dlol and the absence of sulfur-containing metabolites seemed to preclude the
Involvement of glutathlone (L1ngg et al., 1982). As proposed by Kohll et
1832A 9-5 03/29/84
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al. (1976) and Illustrated 1n Figure 9-1, formation of the IsomeMc tr1-
chlorophenols from the arene oxide Intermediates can proceed either by
direct opening of the C-0 bond or by the NIH shift of chlorine.
Differences 1n the rate of metabolism of the different Isomers within a
species have been attributed to the positions of the chlorine atoms on the
benzene ring, with the presence of two adjacent unsubstHuted carbon atoms
facilitating the formation of the arene oxide Intermediate. Halogenated
benzenes without adjacent unsubstHuted carbons may still be metabolized via
an arene oxide Intermediate but at a reduced rate, and should show evidence
of a NIH shift (Matthews and Kato, 1979).
9.1.4. Excretion. L1ngg et al. (1982) measured the 24-hour excretion of
radioactivity 1n the urine and feces of 16 male Charles River rats and 2
rhesus monkeys given a single 10 mg/kg 1.v. or oral dose of 14C-1,2,4-tr1-
chlorobenzene. In the rat, 84% of the oral dose and 78% of the 1.v. dose
were excreted 1n the urine by 24 hours; 11 and 7%, respectively, were the
amounts Identified 1n the feces. In the monkeys, 40% of the oral dose and
22% of the Injected dose appeared 1n the urine and <1% 1n the feces. Smith
and Carlson (1980) orally administered 181.5 mg/kg/day (1 mmol/kg/day) of
14C-1,2,4-tMchlorobenzene 1n corn oil to 4 Sprague-Dawley rats for 7 days
and followed the excretion of radioactivity 1n the feces and 1n the urine
during administration and up to 21 days after the first dose. Fecal elimi-
nation rose slightly during the first 3 days of dosing, after which 1t
declined rapidly and was essentially complete at 15 days of collection,
accounting for -4% of the total dose. Urinary excretion followed a similar
pattern; however, at 21 days after the first dose, radioactivity was still
detectable. Total urinary excretion to this time accounted for -72% of the
total administered radioactivity. As noted by L1ngg et al. (1982), the
1832A 9-6 03/29/84
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00
co
ro
9
i
\
\
NO
I.1. «-1
I
a
OH
a
i. a. 4-Tca
/ \
/ \ /
1.1.4-T«y
-TCP
1.4.1-TCP
». I. i-TO
TO • TMCNKMOMNltM
FIGURE 9-1
o
CO
ro
us
00
Metabolic Pathways for Trlchlorobenzene (TCB) Isomers Through Arene Oxide Intermediates
1n Rabbits
Source: Adapted from KohH et al., 1976
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differences 1n the excretion rate between the rat and monkey may be attrib-
utable to their different pathways of metabolism, since the monkey required
two steps beyond the arene oxide to produce Us urinary metabolite, while
the rat required only one.
Differences 1n the rates of excretion between the Isomers of trlchloro-
benzene have also been reported. Jondorf et al. (1955) found that rabbits
given oral doses of 500 mg/kg of 1,2,3-, 1,2,4- or 1,3,5-tr1chlorobenzene
excreted 78, 42 or 9%, respectively, of the administered dose as monophenols
1n the 5-day urine.
U.S. EPA (1980b), using data from Williams (1959) and Parke and Williams
(1960), estimated the following half-lives 1n the rabbit: 2, 5.5 and 8.5
days for 1,2,3-, 1,2,4- and 1,3,5-tr1chlorobenzene, respectively. The rate
of excretion 1s most likely related to the position of the chlorine atoms on
the benzene ring. Matthews and Kato (1979) hypothesized that two adjacent
unsubstHuted carbon atoms facilitate the formation of the arene oxide
Intermediate and Increase the rate of metabolism and excretion.
9.1.5. Summary. The limited comparative pharmacoklnetlc data available
on the trlchlorobenzenes prevent specification of the absorption, distribu-
tion, metabolism and excretion of the Individual Isomers. From the avail-
able data, 1t seems relatively clear that metabolism 1n at least three
species has a common first step, the production of an arene oxide Intermedi-
ate. Subsequent metabolic steps, however, vary among the species examined,
at least for the most studied Isomer, 1,2,4-tr1chlorobenzene.
In general, the pharmacoklnetlcs of the trlchlorobenzenes are similar to
those described for the halogenated aromatlcs by Matthews and Kato (1979).
The authors observed that these compounds are UpophlUc and that their
I832A 9-8 03/29/84
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metabolism and excretion depends on their conversion to polar Intermedi-
ates. In addition, their UpophHU character provides for ready absorption
from the gastrointestinal tract and Initial distribution to the more highly
perfused tissues, particularly the liver, after which they are either metab-
olized and excreted or redistributed to adipose tissue or skin. Additional
experiments are needed to clarify the relationship of these studies to the
metabolism of trlchlorobenzenes 1n humans.
9.2. EFFECTS IN HUMANS
Information on the health effects of trlchlorobenzenes 1n humans 1s
limited to case reports. Rowe (1975) found that an Individual exposed to
1,2,4-tr1chlorobenzene at 3-5 ppm had eye and respiratory Irritation.
Glrard et al. (1969) reported two cases, one 1n which a 68-year-old woman
who often soaked her husband's work clothes 1n trlchlorobenzene developed
aplastlc anemia, and the other 1n which a 60-year-old man, who had been
occupatlonally exposed to DDT as well as to mono-, d1- and trlchlorobenzenes
for over 30 years, developed anemia.
9.3. MAMMALIAN TOXICOLOGY
9.3.1. Acute Toxldty. Studies of the acute toxldty of the trlchloro-
benzenes have been performed 1n several species using various routes of
administration.
Information on the effects of acute Inhalation exposure to trlchloroben-
zenes 1s limited. In an abstract of a study from the Russian literature
(Gurfeln and Pavlova, 1960), a single high Inhalation dose (doses of
0.005-0.01 mg/8, 1n air or 5-10 mg/m3 were used) of an unspecified Isomer
of trlchlorobenzene to rats resulted 1n Immediate nervousness and plnkness
of mouth, ears and paws. These effects were followed by convulsions and
death within 30 minutes, with edema of livers and kidneys observed upon
1832A 9-9 03/29/84
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necropsy. Unpublished results of a study performed by Treon (1950) were
reported by Coate et al. (1977) and Indicated that the target organs of non-
lethal acute Inhalation exposure to tMchlorobenzenes (a weight-to-weight
mixture of S% 1,2,3- and 92X 1,2,4-tr1chlorobenzene) In cats, dogs, rats,
rabbits and guinea pigs Included the liver, ganglion cells at all levels of
the brain and mucous membranes. Lethal doses resulted 1n local Irritation
of the lungs and functional changes 1n respiration In animals dying after
exposure. Levels and duration of exposure were not given.
Brown et al. (1969) reported the single-dose oral LD for 1,2,4-tM-
chlorobenzene 1n CFE rats to be 756 mg/kg (95X confidence limits 556-939
mg/kg). In CF mice, the single-dose oral LD§ was 766 mg/kg (95% confi-
dence limits 601-979 mg/kg). Death occurred within 5 days 1n rats and 3
days 1n mice.
R1m1ngton and Zlegler (1963) studied the porphyr1a-1ndudng ability of
1,2,4- and 1,2,3-tr1chlorobenzenes administered by gavage to male albino
rats for various time periods (5-15 days). Doses of the Isomers were gradu-
ally Increased until porphyrln excretion was high but fatalities were few.
Porphyrla was Induced by 1,2,4-tr1chlorobenzene when the Isomer was given
for 15 days at 730 mg/kg (3 rats) as evidenced by peak rises 1n urinary
coproporphyrln, uroporphyrln, porphoblUnogen and i-am1nolevu!1n1c add.
At a dose of 500 mg/kg for 10 days (1n 5 rats), peak liver levels of copro-
porphyrln, protoporphyrln, uroporphyrln and catalase were reached. For the
1,2,3- Isomer, urinary excretion of these Indicators peaked at 785 mg/kg for
7 days (3 rats), but to a lesser extent than for the 1,2,4- Isomer. Only
the liver uroporphyrln levels were Increased by administration of l,2,3-tr1-
chlorobenzene at this dose and duration. Glutathlone was found to have a
protective effect on tr1chlorobenzene-1nduced porphyrla.
1832A 9-10 03/29/84
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Brown et al. (1969) determined the single-dose percutaneous ID™ 1n
CFE rats (4 of each sex) to be 6139 mg/kg (95% confidence limits 4299-9056
mg/kg) for 1,2,4-tr1chlorobenzene administered topically and covered with an
Impermeable dressing. All deaths occurred within 5 days. In skin Irrita-
tion studies, 1,2,4-tr1chlorobenzene was applied to the skin of rabbits and
guinea pigs. In the first experiment, two 2x2 cm patches of Unt, each con-
taining 1 ml of the compound, were applied to the shorn backs of rabbits
(4 of each sex) for 6 hours/day for 3 consecutive days and covered with an
Impermeable dressing. For another experiment, rabbits (1 of each sex) and
guinea pigs (5 of each sex) received single uncovered applications of
1,2,4-trlchlorobenzene (1 ml for rabbits, 0.5 ml for guinea pigs) 5
days/week for 3 weeks. The results Indicated that trlchlorobenzene was not
very Irritating, although flssurlng was noted during the 3-week exposure.
Some guinea pigs that died during the 3-week regimen had focal necrosis of
the liver.
Hepatotoxlc effects {fatty Infiltration and necrosis) were reported by
Cameron et al. (1937) following s.c. and/or 1.v. Injection of 500 mg (range
of doses was 1-500 mg) trlchlorobenzene 1n liquid paraffin to rats; the
toxldty was less than that of mono- and o-d1chlorobenzene. Further details
of strain, number of animals or Isomers were not reported.
Robinson et al. (1981), 1n an acute toxldty study to assess the
Increased adrenal weight which was noted 1n a multlgeneratlon study, gave
groups composed of 9-10 preweanlng female Charles River rats 1.p. Injections
of 0, 250 or 500 mg of 1,2,4-tr1chlorobenzene/kg 1n corn oil at 22, 23 and
24 days of age. Significant changes (p<0.05) from control values were
1832A 9_H 03/29/84
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observed upon necropsy at 25 days of age as follows: decreased body weight
and Increased adrenal weight at the high dose; decreased uterus and
Increased liver weights at both doses.
Male Holtzman rats (number not specified) were given single IntrapeM-
toneal Injections of 1,2,4- or 1,3,5-tr1chlorobenzene at a dose of 37 mg/kg
(5 mmol/kg) as a 50% solution 1n sesame oil 1n a volume of 1 ml/kg (Yang
et al., 1979). Controls received an equal volume of sesame oil. After 24
hours, the femoral veins and the common bile duct were cannulated. Both
Isomers produced significant Increases (p<0.05) 1n bile duct-pancreatic
fluid (BDPF) flow with the 1,2,4- Isomer being 4 times more effective than
the 1,3,5- Isomer. SGPT activity was elevated by treatment with l,3,5-tr1-
chlorobenzene and bile flow was elevated by the 1,2,4- Isomer. Both Isomers
caused a decrease 1n BDPF protein concentration.
Several studies have demonstrated the ability of the trlchlorobenzenes
to enhance xenoblotlc metabolism. Carlson, 1n a series of reports (Carlson
and Tardlff, 1976; Carlson, 1977a, 1978, 1981; Smith and Carlson, 1980),
examined the ability of 1,2,4-tr1chlorobenzene to Induce a variety of mlcro-
somal functions and enzymes Including cytochrome c reductase, 0-ethyl
0-p-n1trophenyl phenylphosphothlonate (EPN) detoxification, cytochrome
P-450, glucuronyltransferase, benzpyrene hydroxylase and azoreductase. In a
14-day study by Carlson and Tardlff (1976), dally doses of 1,2,4-tr1chloro-
benzene 1n corn oil were administered orally to groups of 6 male albino rats
at 10, 20 and 40 mg/kg. All the above functions and enzymes Increased sig-
nificantly (p<0.05) except benzopyrene hydroxylase. In a 90-day study by
the same Investigators, all the functions and enzyme activities Including
benzopyrene hydroxylase Increased significantly (p<0.05) at 10-40 mg/kg/day
and remained significantly elevated after a 30-day recovery period. In a
1832A 9-12 03/29/84
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similar study, Smith and Carlson (1980) administered 1,2,4-tMchlorobenzene
at 181.5 mg/kg/day (1 mmol/kg/day) to rats for 7 days, and measured recovery
at 1, 6, 11 and 16 days. EPN detoxification was still significantly
(p<0.05) elevated at 11 days; p-n1troan1sole demethylatlon at 16 days; cyto-
chrome c reductase at 6 days; and cytochrome P-450 at 11 days. In a similar
study by Carlson (1977b), 7-day administration of 1,3,5-trlchlorobenzene at
100-200 mg/kg/day significantly (p<0.05) Increased EPN detoxification, UOP
glucuronyltransferase, and cytochrome c reductase, and significantly
decreased hepatic G-6-P; benzpyrene hydroxylase, azoreductase and serum
Isodtrate dehydrogenase were not significantly affected at 200 mg/kg/day,
In the same study, jm vivo hepatotoxldty of carbon tetrachlorlde (one dose
of 0.5 ml/kg) was significantly (p<0.05) enhanced by 14-day pretreatment
of rats with 1,2,4-tr1chlorobenzene. Glucose-6-phosphatase activity was
significantly (p<0.05) decreased by pretreatment with 1,2,4-tr1chlorobenzene
at 5 mg/kg/day, and 1soc1trate dehydrogenase was decreased by pretreatment
at 20 mg/kg/day.
The 1,2,4- Isomer, and to a lesser extent the 1,3,5- Isomer, were also
shown to Induce hepatic esterases (Carlson et al., 1979; Carlson, 1980). In
studies similar to those previously described, rats receiving dally oral
doses of 18.2 mg 1somer/kg (0.1 mmol/kg) for 14 days were killed 24 hours
later and hepatic mlcrosomes were prepared. The l,2,4-1somer was an
effective Inducer of both acetanlllde esterase and acetanlllde hydroxylase,
while the l,3,5-1somer Induced only the esterase and to a lesser degree than
did 1,2,4-trlchlorobenzene (Carlson et al., 1979). The l,2,4-1somer also
Induced hepatic arylesterase, while 1,3,5-trlchlorobenzene did not (Carlson,
1980). Pretreatment of rats with 181.5 mg/kg/day (1 mmol/kg/day) of either
Isomer resulted 1n Induction of procalne esterase (Carlson et al., 1979).
1832A 9-13 03/29/84
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In a series of experiments, Ar1yosh1 et al. (1975a,b,c) studied the
effects of the trlchlorobenzenes on Induction of hepatic mlcrosomal pro-
teins, phosphol1p1ds and enzymes, especially 1n relation to the activity of
6-am1nolevul1n1c add synthetase, the rate limiting enzyme 1n the bio-
synthesis of heme. The three tMchlorobenzene Isomers were administered
orally to groups of 2-6 female VMstar rats at a dose of 250 mg/kg/day for 3
days, after which the rats were killed and mlcrosomes were prepared. The
results Indicated that trlchlorobenzenes Increased the levels of mlcrosomal
proteins, phosphollplds and cytochrome P-450, and enhanced the activities of
aniline hydroxylase, amlnopyrlne demethylase and 6-am1nolevul1n1c acid
synthetase, with the l,2,4-1somer being the most effective (Ar1yosh1 et al.,
1975a,b). The dose response of these effects to 1,2,4-tr1chlorobenzene were
determined (Ar1yosh1 et al., 1975c) for groups of 2-6 female Wlstar rats
treated orally with single doses of 0, 125, 250, 500, 750, 1000 and 1500
mg/kg. The results Indicated that 24 hours after the administration of the
Isomer, mlcrosomal protein was elevated at >750 mg/kg and glycogen content
was decreased at >500 mg/kg. The activities of amlnopyrlne demethylase and
aniline hydroxylase and the content of cytochrome P-450 were Increased at
>250 mg/kg, as was 6-am1nolevul1n1c add synthetase activity.
9.3.2. Subchronlc Toxldty. The effects of trlchlorobenzene following
subchronlc Inhalation, as well as oral and dermal exposure, have been
Investigated 1n a variety of species. Toxldty data for the trlchloroben-
zenes can be found 1n Table 9-2.
Kodba et al. (1981) exposed 20 male Sprague-Dawley rats, 4 male New
Zealand rabbits and 2 male beagle dogs by Inhalation to 1,2,4-tr1chloroben-
zene (99.4% pure) at levels of 0, 223 mg/m3 (30 ppm) or 742 mg/m3 (100
ppm) for 7 hours/day, 5 days/week for a total of 30 exposures In 44 days.
1832A 9-14 03/29/84
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TABLE 9-2
Summary of Subchronlc and Chronic Tox1c1ty Studies on Trlchlorobenzenes
CD
CO
VO
I
O
to
O
V.
co
Species Route
Rat Inhalation
Rats, rabbits. Inhalation
two dogs
Rat Inhalation
Rat Inhalation
Rabbits, Inhalation
monkeys
Monkey oral
Rat oral
Rat oral
Mouse oral
Dose
74.2, 742 or
7423 mg/m1
of 1,3.5-TCB
223 or 742 mg/m»
of 1.2.4-TCB
22.3 or
74.2 mg/ra»
of 1,2,4-TCB
186, 371 or
742 mg/m*
of 1.2,4-TCB
186, 371 or
742 mg/m1
of 1.2,4-TCB
1. 5, 25, 90.
125 or 173.6
mg/kg/day
of 1,2,4-TCB
50, 100 or
200 mg/kg/day
of 1,2.4-TCB
10. 20 or
40 mg/kg/day
of 1,2,4-TCB
600 ppm diet
(0.078 mg/kg/
day) of
1,2,4-TCB
Duration
6 hr/day, 5 day/wk
for up to 13 wk
7 hr/day, 5 day/wk;
total of 30 expo-
sures In 44 days
6 hr/day, 5 day/wk,
3 mo
7 hr/day. 5 day/wk.
26 wk
7 hr/day, 5 day/wk.
26 wk
30 days
30, 60, 90 or
120 days
90 days
6 mo
Effects Reference
No hepatotoxldty; three high-dose rats had Sasmora and Palmer,
squamous metaplasia and focal hyperplasla 1981
of respiratory epithelium, believed to be
reversible
Increase 1n urinary excretion of porphyrla Koclba et al., 1981
1n exposed rats; Increase 1n liver weights
1n high-dose rats and dogs; Increased kid-
ney weights 1n high-dose rats
Increase In urinary porphyrln excretion In Watanabe et al., 1978
high-dose rats; no effects 1n 22.3 mg/m*
group
Enlarged hepatocytes and nondose-dependent Coate et al.. 1977
hepatocytes vacuol1zat1on, liver granulance,
biliary hyperplasla and kidney hyaline de-
generation at 4 and 13 wk; no hlstopathology
evident at 26 wk
No treatment related changes at 26 wk Coate et al., 1977
<25 mg/kg/day - no effects observed; Smith et al., 1978
>90 mg/kg/day - observed toxic 1ty and death
Increases 1n liver weights, liver porphyrlns Carlson, 1977b
and urine porphyrlns. dose and time related
Increase 1n I1ver-to-body weight ratio 1n Carlson and Tardlff,
high-dose group; changes In enzyme actlva- 1976
tlon at all doses
No effects Goto et al.. 1972
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1ABIF 9-2 (cont. )
Species
Guinea pig
Mouse
Rats
Rabbits
Route
dermal
dermal
oral
(drinking
water )
dermal
Dose
0.5 ml/day
of 1,2,4-TCB
0.003 ml/paint-
ing of 30 and
60% solution In
acetone of
1.2,4-TCB
25, 100 or
400 mg/t
of 1,2,4-TCB
30, 150 or
450 mg/kg/day
of 1,2,3-TCB
Duration
5 day/wk, 3 wk
2 t1mes/wk, 2 yr
F0 to F2
generations
5 day/wk, 4 wk
Effects Reference
Death following extensor convulsion; livers Brown et al., 1969
showed necrotlc foe!
Painting Induced excitability, panting and Yamamoto et al., 1957
epidermal thickening, Inflammation and
keratlnlzatlon; Increased organ weights and
mortality
Enlarged adrenals In FQ and FI generations Robinson et al., 1981
Dose-related skin Irritation; Increase 1n Rao et al.. 1982
urinary coproporphyrln In high-dose males
and slight pallor of liver 1n males and
females
1,2,3-TCB = 1,2.3-tMchlorobenzene; 1,2,4-TCB = 1,2,4-trlchlorobenzene; 1,3,5-TCB = 1,3,5-tMchlorobenzene
o
CO
-------
There were no significant effects on body weight, hematologlc Indices or
serum biochemistry tests. Upon necropsy, gross and comprehensive hlstologl-
cal examination revealed no significant treatment-related effects 1n any of
the species. At the 742 mg/m3 level, Increased liver weights were
detected 1n dogs and rats and Increased kidney weights 1n rats. Urinary
excretion of porphyrln was Increased 1n rats exposed to 1,2,4-trlchloroben-
zene at 223 or 742 mg/m3, which the Investigators Interpreted as a com-
pound-specific physiologic effect rather than a toxic effect. A follow-up
study supported this Interpretation. The same Investigators exposed male
and female Sprague-Dawley rats to 1,2,4-tr1chlorobenzene at 0, 22.3 mg/m3
(3 ppm) or 74.2 mg/m3 (10 ppm) for 6 hours/day, 5 days/week for 3 months.
The results, which were reported 1n an abstract (Watanabe et al., 1978),
Indicated that urinary excretion of porphyrlns was slightly Increased 1n the
74.2 mg/m3 group during exposure, but returned to control range 2-4 months
post-exposure. Since this appeared to be the most sensitive Indicator 1n
rats, and exposure to trlchlorobenzene at 22.3 mg/m3 did not cause
Increased porphyrln excretion, 22.3 mg/m3 was considered a no-observed-
adverse-effect level (NOAEL) for rats by the authors.
Sasmore and Palmer (1981) exposed male and female outbred albino CD rats
(20/group) to 1,3,5-tr1chlorobenzene vapor at 0, 74.2 mg/m3 (10 ppm), 742
mg/m3 (100 ppm) or 7423 mg/m3 (1000 ppm) for 6 hours/day, 5 days/week
for up to 13 weeks. No significant effects were observed on body weights,
food consumption, standard hematologlc and clinical chemistry parameters or
on methemoglobln and porphyrln levels. In a subgroup of animals killed
after 4 weeks of exposure, there was a significant Increase 1n the I1ver-to-
body weight and I1ver-to-bra1n weight ratios 1n the male rats of the high
exposure level group, but these effects were not observed at 13 weeks.
1832A 9-17 03/29/84
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Since gross and microscopic pathologic examinations of the liver revealed no
treatment-related abnormalities, the authors concluded that the exposure did
not cause hepatotoxldty. Microscopic examinations, however, revealed that
three high dose rats had squamous metaplasia and focal hyperplasla of the
respiratory epithelium, which the authors believed to be reversible.
Coate et al. (1977) exposed groups of 30 male Sprague-Dawley rats, 16
male New Zealand rabbits and 9 male monkeys (Macaca fasclcularls) to 99.07%
pure 1,2,4-trlchlorobenzene vapor at levels of 0, 186 mg/m3 (25 ppm), 371
mg/m3 (50 ppm) or 742 mg/m3 (100 ppm) for 7 hours/day, 5 days/week for
26 weeks. Pulmonary function and operant behavior tests 1n the monkeys,
ophthalmic examinations 1n the rabbits and monkeys, and measurements of body
weight, hematologlc Indices and serum biochemistry parameters 1n all species
were conducted before and during the exposure period. Subgroups of 5 rats
each were killed after 4 and 13 weeks of exposure; all remaining rats were
killed after 26 weeks for hlstologlcal examination of selected tissues. No
treatment-related effects at any observation time were seen with respect to
body weight, survival, hematology or serum chemistry for any of the
species. No ophthalmic changes were observed 1n rabbits or monkeys. Pul-
monary function and operant behavior were unaffected 1n monkeys. Hlstologl-
cal examination of rat tissues revealed that treated animals had enlarged
hepatocytes that were more prominent at 4 weeks than at 13 weeks after expo-
sure, and at 371 and 742 mg/m3 than at 186 mg/m3. Other changes 1n
treated rats that did not appear to be dose-dependent were vacuollzatlon of
hepatocytes at 4 and 13 weeks, slightly more severe granuloma of the liver
at 4 weeks and biliary hyperplasla at 4 and 13 weeks. A nondose-related In-
crease 1n the severity of kidney hyaline degeneration was observed 1n test
rats at 4 weeks. This lesion was slightly more severe 1n the high dose
1832A 9-18 03/29/84
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group at 13 weeks. These effects appeared to be transient; rats necropsled
after 26 weeks of exposure had none of these changes. Likewise, hlstologl-
cal examination of selected tissues from rabbits and monkeys revealed no
treatment-related changes after 26 weeks of exposure.
Carlson and Tardlff (1976) assessed the effects of 14- or 90-day oral
administration of 1,2,4-tr1chlorobenzene 1n corn oil compared to corn oil
controls 1n male CD rats. In the 14-day studies, the effects examined were
lethality, hepatotoxldty and the Influence on hexabarbltal sleeping time
and other parameters of xenoblotlc metabolism. A dose of 600 mg/kg, the
highest dose administered, caused no deaths during the 14-day administration
period. Hepatotoxldty was evaluated by dosing at 0, 150, 300 or 600
mg/kg/day and determining serum 1soc1trate dehydrogenase and liver glucose-
6-phosphatase activities. Although no dose-related changes 1n serum 1so-
cltrate dehydrogenase activity was observed, liver glucose-6-phosphatase
activity was significantly decreased at >300 mg/kg (p<0.05). Hexabarbltal
sleeping time was significantly decreased at 600 mg/kg/day (the only dose
examined); this effect persisted through a 14-day recovery period. In rats
receiving 14 dally doses at 0, 10, 20 or 40 mg/kg, there was a significant
dose-related Increase 1n I1ver-to-body weight ratio at >10 mg/kg/day
(p<0.05). Significant dose-related Increases were also observed 1n activi-
ties or contents of cytochrome c reductase (at >10 mg/kg), cytochrome P-450
(at >20 mg/kg), glucuronyltransferase (at >20 mg/kg), azoreductase (at >10
mg/kg) and the rate of detoxlcatlon of EPN (at >10 mg/kg). These results
Indicated that the doses, while causing a slight degree of hepatic Injury,
significantly enhanced xenoblotlc metabolism.
In 90-day studies by Carlson and Tardlff (1976), the effects of oral
dosing of male CD rats (6 animals/group) at 0, 10, 20 or 40 mg/kg/day with
1832A 9-19 03/29/84
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1,2,4-tr1chlorobenzene 1n corn oil on weight gain, liver weight, hemoglobin
content, packed cell volume and the Indicators of xenoblotlc metabolism were
evaluated. No effects on weight gain and no consistent alteration 1n hemo-
globin content or packed cell volume were observed. At 40 mg/kg, there was
a statistically significant Increase (p<0.05) In I1ver-to-body weight ratios
that persisted throughout a 30-day recovery period. Following 90-day admin-
istration, cytochrome c reductase activity was Increased at >10 mg/kg, with
recovery after 30 days; cytochrome P-450 levels Increased at >20 mg/kg, fol-
lowed by recovery; glucuronyltransferase activity decreased at >10 mg/kg;
EPN detoxlcatlon Increased at >20 mg/kg; benzopyrene hydroxylase activity
Increased 2-fold at 40 mg/kg; and azoreductase activity Increased at >10
mg/kg.
Groups of 5 female rats (strain not reported) received dally oral doses
of 0, 50, 100 or 200 mg 1,2,4-tr1chlorobenzene/kg/day 1n corn oil for 30,
60, 90 or 120 days (Carlson, 1977b). Significant Increases were observed In
liver porphyrlns at >100 mg/kg after 30 days exposure and In urinary
porphyrlns at 200 mg/kg after 30 days. For the 30-day study, slight but
significant Increases were also observed 1n liver weights at 200 mg/kg.
When the compound was administered for 60 days, only the liver weights were
Increased. The administration of 1,2,4-tr1chlorobenzene for 90 days
resulted In slight but significant Increases 1n liver weights at >50 mg/kg,
1n liver porphyrlns at >100 mg/kg and 1n urine porphyrlns at 200 mg/kg. A
significant Increase was observed for liver porphyrlns when the compound was
given at >50 mg/kg for 120 days. The excretion of 6-am1nolevul1n1c acid
and porphoblUnogen 1n the urine was not Increased at any dose given for any
duration. When the author compared the 1,2,4-tr1chlorobenzene results with
the results for hexachlorobenzene, he concluded that tMchlorobenzene
1832A 9-20 03/29/84
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Induced porphyrU was very small compared to the hexachlorobenzene Induced
porphyrla (Carlson, 1977b).
A 90-day oral study by Smith et al. (1978), reported 1n an abstract, was
reviewed by U.S. EPA (1980b), who gave further details of the study after
communication with the authors. Rhesus monkeys (4/group) were given 1,2,4-
trlchlorobenzene 1n dally oral doses of 1, 5, 25, 90, 125 or 173.6 mg/kg.
No toxic effects were observed at <25 mg/kg, while doses of >90 mg/kg were
observed to be toxic, and the 173.6 mg/kg dose was lethal within 20-30 days.
There were no deaths observed 1n the 1, 5 and 25 mg/kg groups; one death
occurred 1n each of the 90 mg/kg and 125 mg/kg groups and two deaths occured
1n the 173.6 mg/kg group. Animals on the highest dose exhibited severe
weight loss and predeath find tremors. All of the animals 1n the highest
dose group had elevated BUN, Na*, K*. CPK, S60T, SGPT, LDH and alkaline
phosphatase as well as hypercalcemla and hyperphosphatemla from 30 days on.
Smith et al. (1978) have been using the urinary pattern of chlorguanlde
metabolites as an Indication of cytochrome P-450 dependent drug metabolism.
At the high doses, monkeys showed evidence of the hepatic Induction as well
as Increased clearance of 1.v. doses of labeled TC8. Further Information on
the study (Smith, 1979) gave evidence of liver enzyme Induction 1n the 90,
125 and 174 mg/kg animals. There were some pathological changes noted In
the livers of the high dose groups, primarily a fatty Infiltration. The
point at which there was no effect related to the compound was at the 5
mg/kg level. Since only an abstract of this study was available and since
the Interpretation of this study was complicated by the use of other drugs
and weight losses 1n the control animals, a valid no-observed-effect level
(NOEL) cannot be derived from these data.
Two studies have assessed the dermal toxldty of the trlchlorobenzenes.
Powers et al. (1975) applied technical grade 1,2,4-tr1chlorobenzene at con-
1832A 9-21 03/29/84
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centratlons of 5 or 25% 1n petroleum ether, or 100% 1,2,4-tr1chlorobenzene
topically 1n 0.2 ml volumes to the ventral surface of the ears of New Zea-
land rabbits (groups of 12 each), 3 times weekly for 13 weeks; a control
group received petroleum ether only. Rabbits exposed to 5% trlchlorobenzene
and controls had slight redness and scaling. Dermal responses at 25 and
100% of the compound Included slight to severe erythema, severe scaling,
desquamatlon, encrustation, and some hair loss and scarring. The responses
were characterized by acanthosls and keratosls, typical of moderate to
severe Irritation and probably attributable to degreaslng action. No overt
signs of systemic toxldty were noted, body weight gain was comparable 1n
all groups, and none of the animals showed meaningful changes 1n gross
pathology. The Investigators noted that this contrasted with the findings
of Brown et al. (1969), who reported that some guinea pigs, exposed topic-
ally to 1,2,4-trlchlorobenzene at 0.5 ml/day, 5 days/week for 3 weeks,
died following extensor convulsions and their livers showed necrotlc foci.
This difference 1n results may be attributed to the site of application
(Brown et al., 1969, used the dorsal m1d!1ne for application, a more exten-
sive exposure site), the volume applied (0.5 ml vs. 0.2 ml), the species
used, and more frequent (5 times/week vs. 3 times/week) application,
although the total number of exposures was less (5x3 weeks vs. 3x13 weeks).
Rao et al. (1982) applied technical grade trlchlorobenzene [1,2,4- (70%)
and 1,2,3-trlchlorobenzene (30%)] 5 days/week for 4 weeks, at doses of 0,
30, 150 or 450 mg/kg/day, to the dorsal skin (4x4 Inch area) of groups (5 of
each sex) of New Zealand rabbits weighing ~3 kg. One rabbit died after 18
applications, but the Investigators were unable to determine the cause of
death by either gross or hlstologlc examination. Gross and hlstologlc
examination of the skin showed evidence of moderate Irritation at the hlgh-
1832A 9-22 03/29/84
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est dose and less Irritation at the lower doses. This Irritation evidence
consisted of epidermal scaling, thickening, fissures, ulcers and erythema.
No treatment-related change was observed 1n clinical chemistry (BUN, glu-
cose, SGPT, SAP) or hematology. A slight but significant Increase 1n
urinary coproporphyrln was observed 1n high-dose males (450 mg/kg/day) at
day 24; none was seen 1n females. This slight porphyrla and a slight gen-
eralized pallor of the liver (3/5 males, 4/4 females) were the only signs of
systemic toxldty. Extensive hlstologlc examination of numerous tissues
failed to show any treatment-related abnormalities. The volume of tM-
chlorobenzene applied at the dose levels 1n this study can be calculated as
=0.06 mil (30 mg/kg), 0.31 ml (150 mg/kg) and 0.93 ml(450 mg/kg) by
multiplying the dose 1n g/kg by the weight of the rabbits (3 kg) and divid-
ing by the density of tMchlorobenzene (1.45).
9.3.3. Chronic Toxldty. No studies on the effects of the trlchloroben-
zenes following chronic Inhalation exposure were available for review; how-
ever, a chronic skin painting study was encountered. Goto et al. (1972)
conducted a 6-month feeding study 1n mice using hexachlorocyclohexane
Isomers and their metabolites, Including 1,2,4-tr1chlorobenzene. Male mice
(20/group) of the ICR-JCL strain (age at Initiation 5 weeks, average weight
26.5 g) received a diet containing 600 ppm of trlchlorobenzene (78 pg of
compound/kg body weight, assuming mice consume 13% of their body weight 1n
food per day). The weight gain of treated mice did not differ from controls
during the 6-month exposure. At 26 weeks, 10 mice were killed and liver,
heart and kidneys were weighed; no abnormal weight changes were observed.
Macroscopic and hlstologlc examination of the liver revealed no hepatic
tumors or any other lesions.
1832A 9-23 03/29/84
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Yamamoto et al. (1957) studied the toxIcHy of 1,2,4-tr1chlorobenzene
when painted on the skin of Slc:ddy mice 2 times/week for 2 years. Groups
consisted of 75 mice/sex receiving 0.03 ml applications of the compound as
30 or 60% solutions 1n acetone. Controls consisted of 50 mice/sex and
received only acetone. The skin painting produced general symptoms of
excitability and panting, local skin thickening, kerat1n1zat1on and Inflam-
mation of the epidermis. These effects were not observed 1n controls. For
the 30% tMchlorobenzene groups, mortality was Increased 1n females (5/75
survived for 83 weeks compared with 11/50 controls). The mean survival days
were 357+.125.4 for treated females compared with 423.8+145.0 for controls
(p<0.01). The survival of males at this exposure level was not signifi-
cantly different from that of controls. Spleen weights were significantly
Increased (p<0.05) and left adrenal weights were significantly decreased
(p<0.01) for treated males when compared with controls. HematologU and
blood chemistry Indices were essentially unchanged with the exception of
Increased red blood cell counts 1n treated males (p<0.05) and decreased
CT concentration (p<0.01). For the 60% solution, 6/75 treated females
survived for 83 weeks. Mean survival days were 320.2+147.7 for treated
females compared with 423.8+J45.0 for controls (p<0.001). Eight of 75
treated males survived for 83 weeks compared with 9/50 control males. Mean
survival days were 288.0+173.7 for treated males and 363.9+J73.9 for con-
trols (p<0.05). Significant differences 1n organ weights from control
values were seen 1n the spleens of males (p<0.01) and the adrenals of
females (p<0.05). Hematologlc and blood biochemistry changes were seen 1n
Increased lymphocyte counts 1n treated females (p<0.05), and 1n Increased
SGOT (p<0.05), SGPT (p<0.001) and BUN (p<0.01) for treated males.
9.3.4. Mutagenldty. Schoeny et al. (1979) and Lawlor et al. (1979)
examined the mutagenlc potential of 1,2,4-tr1chlorobenzene In Salmonella
1832A 9-24 03/29/84
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typhlmuMum tester strains TA98, TA100, TA1535 and TA1537, using the plate
Incorporation technique. Schoeny et al. (1979) used 8 concentrations of
trlchlorobenzene ranging from 102 yg/plate to 1.4xlOs vig/plate. The
toxic dose was determined as 1599 pg/plate (killing of one or more strain
on mutagenesls plates). Trlchlorobenzene was negative for mutagenldty 1n
the absence and presence of S-9 mlcrosomal fractions from unlnduced rats,
from rats Induced by the polychloMnated blphenyl, Aroclor 1254, and from
rats homologously Induced with trlchlorobenzene.
The study of Lawlor et al. (1979), reported 1n an abstract, used the
TA1538 strain of S. typhlmurlum 1n addition to the strains previously men-
tioned. Negative results were obtained for five unspecified concentrations
tested 1n the presence and absence of rat liver mlcrosomes Induced by
Aroclor 1254. Because these results were reported 1n an abstract without
the details of the experimental procedures used, the results cannot be crit-
ically evaluated.
The negative results 1n the Salmonella h1st1d1ne reversion assay are not
unexpected because this test system 1s generally Insensitive to chlorinated
compounds.
9.3.5. CardnogenlcHy. Yamamoto et al. (1957) applied 1,2,4-tr1chloro-
benzene 1n acetone to the skin of Slc.ddy mice 2 times/week for 2 years.
The solution of 1,2,4-tr1chlorobenzene was 60% for the high dose and 30% for
the low dose and the volume applied was 0.03 ma/application. Each treated
group contained 75 animals and there were 50 control animals for each sex.
Growth rates In treated and control mice were comparable through 83 weeks.
Mean survival days were significantly reduced 1n the 60% 1,2,4-tMchloroben-
zene groups of males and females and also 1n the 30% treatment group of
females.
1832A 9-25 03/29/84
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Hlstopathology showed some organs sites had Increased non-neoplast1c
lesions. Assuming that all 75 animals 1n the treated groups were examined
and all 50 1n the control groups were examined, there would be Increases 1n
lesions 1n the males 1n lung, liver, kidney, adrenal, spleen and lymph node
at the high dose, and 1n all of these organs except lymph node 1n the
females at the high dose. Unfortunately, the English translation of
Japanese text Is not very specific 1n describing the nature of the lesion
making 1t difficult to use this Information 1n the Interpretation of the
tumor findings.
No single tumor type was Increased significantly over the control Inci-
dence but among males nine different tumors were found 1n the high dose
group as compared with two 1n the low dose and two 1n the control group. In
females there were 11 different tumors 1n the high dose group as compared
with three In the low dose and eight 1n the control group. The authors do
not state whether these tumors were all found 1n different Individual ani-
mals or whether these were multiple tumors In the same animal. Therefore,
the actual Incidence 1n terms of the number of tumor bearing animals 1s not
known.
Further Information from this study 1s necessary for full Interpreta-
tion. This single study 1s clearly Inadequate for making any conclusions
about cardnogenlclty 1n humans.
9.3.6. Reproductive and Teratogenlc Tox1c1ty. Studies on the reproduc-
tive or teratogenlc effects of trichlorobenzenes following Inhalation expo-
sure were not found 1n the available literature. Robinson et al. (1981)
reported a mult1generat1on study of the reproductive effects of l,2,4-tr1-
chlorobenzene following oral administration. Charles River rats were con-
tinuously exposed to the compound at 0, 25, 100 or 400 ppm 1n drinking
1832A 9-26 03/29/84
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water. The authors calculated the dosages for the FQ generation based on
water consumption data to be: for females at 29 days of age, 8.3+0.8,
28.0+1.2, 133.2+J3.4 mg/kg/day, respectively; for males at 29 days of age,
8.5+0.6, 27.6+1.6, 133.6+15.6 mg/kg/day, respectively; for females at 83
days of age, 3.7+0.1, 14.8+_1.0, 53.6+_3.9 mg/kg/day, respectively; for males
at 83 days of age, 2.5+0.1, 8.9+0.3, 33.0+J.4 mg/kg/day, respectively. The
exposure period began with the birth of the FQ generation and continued
through 32 days of age of the F? generation. Each treatment group consis-
ted of 17-23 Utters. No treatment-related effects were noted with respect
to fertility, neonatal weights, maternal weights, Utter sizes, preweanlng
viability or postweanlng growth 1n any generation. Treatment-related dif-
ferences were seen with respect to food Intake and water consumption 1n F
males and females, but they were Inconsistent and did not occur In other
generations. Blood chemistry analyses and locomotor activity measurements
revealed no overt hematologlc or neurologic effects, and histologlcal exami-
nation of the livers and kidneys of the FI generation rats revealed no
damage. At the 400 ppm dose level, significantly enlarged adrenals 1n both
sexes of the F and F rats were observed at 95 days of age (p<0.006).
A follow-up acute toxldty study showed that this effect could result from
three dally 1.p. Injections of 500 mg 1,2,4-tr1chlorobenzene/kg.
Black et al. (1983) reported 1n an abstract a teratogenldty study 1n
pregnant Wlstar rats using 1,2,4-, 1,2,3- or 1,3,5-tr1chlorobenzene adminis-
tered by gavage 1n doses of 75-600 mg/kg on days 6-15 of gestation (gesta-
tlonal day 0 or 1 not defined). Upon necropsy (gestatlonal day not speci-
fied), thyroid and liver lesions and reduced hemoglobin and hematocrlt
values were observed 1n treated dams (doses not specified). No teratogenlc
effects were observed In the pups; however, pups exposed to the 1,2,4- and
1,3,5- Isomers (doses not specified) had mild osteogenlc changes.
1832A 9-27 03/29/84
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9.4. INTERACTIONS
Several studies discussed 1n Section 9.3.1. on acute toxldty have
demonstrated that the Isomers of trlchlorobenzene are capable of affecting
xenoblotlc metabolism by Inducing a variety of the hepatic drug-metabolizing
enzymes 1n rats. These Include cytochrome c reductase, cytochrome P-450,
glucuronyltransferase, benzpyrene hydroxylase, azoreductase (Carlson and
Tardlff, 1976; Carlson, 1977, 1978, 1981; Smith and Carlson, 1980), aceta-
nH1de esterase and acetanlUde hydroxylase, procalne esterase (Carlson et
al., 1979), arylesterase (Carlson, 1980), mlcrosomal proteins, phosphollplds
and amlnopyrene hydroxylase (Ar1yosh1 et al., 1975a,b,c). That trlchloro-
benzenes enhance xenoblotlc metabolism has been demonstrated by Smith and
Carlson (1980) and Carlson (1977a), who showed that administration of
1,2,4- or 1,3,5-trlchlorobenzene to groups of 4 male Sprague-Dawley rats for
7 days Increased EPN detoxlcatlon.
Townsend and Carlson (1981) demonstrated that 1,2,4-tr1chlorobenzene,
administered by gavage 1n corn oil to groups of five male Swiss mice at
181.5 mg/kg (1 mmol/kg) for 7 days, Increased the LD5Q and protected the
mice against the toxic effects of malathlon, malaoxon, parathlon and para-
oxon when graded doses of these Insecticides were administered on the day
following the last dose of trlchlorobenzene.
Experiments comparing the effects of trlchlorobenzenes with the effects
of phenobarbHal and 3-methylcholanthrene Indicated that the Inductions of
mlcrosomal enzymes by trlchlorobenzenes are of the phenobarbHal type
(Carlson, 1978).
9.5. SUMMARY
The trlchlorobenzenes appear to enter the body readily via Inhalation,
Ingestlon and dermal absorption; however, data were not available to quantl-
1832A 9-28 03/29/84
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tate the rates of these processes nor of any of the pharmacoklnetlc pro-
cesses. Initial distribution of the trlchlorobenzenes and metabolites Is
mainly to the liver, kidneys and adrenals, followed by migration to adipose
tissue or metabolism to polar compounds that are more readily excreted.
Metabolism appears to be Initially to arene oxides, and then by different
routes 1n different species, with different rates of excretion. Species
differences are such that extrapolation of adverse effects to humans prob-
ably requires the support of comparative metabolic data.
Human exposure to 1,2,4-tr1chlorobenzene at 3-5 ppm causes eye and
respiratory Irritation (Rowe, 1975). The only other data on human exposure
are Individual case reports of aplastlc anemia of persons exposed occupa-
tlonally or domestically (Glrard et al., 1969).
The effects 1n mammals of acute exposure by various routes to trlchloro-
benzenes Include local Irritation, convulsions and death. Livers, kidneys,
adrenals, mucous membranes and brain ganglion cells appear to be target
organs with effects Including edema, necrosis, fatty Infiltration of livers,
Increased organ weights, porphyrln Induction and mtcrosomal enzyme Induction.
Quantitative data on the toxic effects of trlchlorobenzene following
subchronlc exposure by various routes were obtained In a variety of
species. In general, these studies Indicate that the liver and kidney are
target organs. Inhalation of 1,2,4-tr1chlorobenzene at >74.2 mg/m3 (10
ppm) for 6 hours/day, 5 days/week for up to 26 weeks Induced hepatocyto-
megaly and hyaline degeneration 1n several species (Kodba et al., 1981;
Watanabe et al., 1978; Coate et al., 1977), although these effects may be to
some extent reversible. One study (Watanabe et al., 1978) Identified 22.3
mg/m3 (3 ppm) as a NOAEL 1n rats. Sasmore and Palmer (1981) reported that
some rats exposed by Inhalation to 1,3,5-trlchlorobenzene at 7423 mg/m3
1832A 9-29 03/29/84
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(1000 ppm) for 13 weeks showed squamous metaplasia and focal hyperplasla of
the respiratory epithelium, which appeared to be reversible. Subchronlc
oral studies have also found that the tMchlorobenzenes Induce hepatic xeno-
blotlc metabolism (Carlson and Tardlff, 1976; Smith et al., 1978) and por-
phyrla (Carlson, 1977b). Subchronlc dermal exposure resulted 1n mild to
moderate Irritation (Powers et al., 1975; Rao et al., 1982).
One chronic study, on the effects of trlchlorobenzene painted on the
skin of mice for 2 years, reported Increased mortality 1n females at the low
dose (30% solution 1n acetone) and 1n both sexes at the high dose (60%
solution) (Yamamoto et al., 1957). No tumorlgenlc effects were seen.
Results of two reports on mutagenldty tests with Salmonella typhlmurlum
test strains were negative (Schoeny et al., 1979; Lawlor et al., 1979).
However, this test system 1s generally Insensitive to chlorinated compounds.
A multlgeneratlon study of the reproductive effects of oral exposure to
trlchlorobenzene (Robinson et al., 1981) and an oral teratogenldty study In
rats (Black et al., 1983) failed to show effects on reproduction or fetal
development, although pups had mild osteogenlc changes.
1832A 9-30 03/29/84
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10. TETRACHLOROBENZENES
Approximately 50 million pounds of the three tetrachlorobenzene Isomers
were produced annually 1n the United States, and the 1,2,4,5- Isomer was
produced the most (U.S. EPA, 1981). Recent Information Indicates that the
production of the tetrachlorobenzenes have been substantially reduced or
have been stopped for the present time (U.S. EPA, 1983). The 1,2,3,4- and
1,2,3,5- Isomers have limited use Industrially and are byproducts 1n the
synthesis of 1,2,4,5-tetrachlorobenzene. The 1,2,4,5- Isomer 1s primarily
used as an Intermediate 1n the synthesis of fungicides, bacteMddes and
herbicides (see Sections 4.1. and 4.2.) (U.S. EPA, 1977). Tetrachloroben-
zene Isomers have been detected 1n environmental samples as well as In human
tissues and breath, but no quantitative exposure assessment has been com-
pleted (see Sections 4.3. and 4.4.). Fish and other organisms bloaccumulate
the tetrachlorobenzenes, Indicating that human exposure from the food chain
1s likely along with human atmospheric exposure (see Section 4.4.).
10.1. PHARMACOKINETICS
No studies describing the absorption, distribution, metabolism or excre-
tion of 1,2,3,4-, 1,2,3,5- or 1,2,4,5-tetrachlorobenzene following Inhala-
tion exposure were located In the available literature. Several oral
studies describing the pharmacoklnetlcs of the three tetrachlorobenzene
Isomers 1n rats, rabbits and dogs are available and are discussed 1n detail
below.
10.1.1. Absorption. Jondorf et al. (1958) examined the absorption of
1,2,3,4-, 1,2,3,5- and 1,2,4,5-tetrachlorobenzene from the gastrointestinal
tract of female Chinchilla rabbits. Groups of three rabbits were given a
single dose of the tetrachlorobenzene Isomers by stomach tube at a dose
level of 500 mg/kg 1n a 10% solution 1n arachls oil. Through 6 days post-
1833A 10-1 03/29/84
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dosing, the percentages of the administered doses recovered 1n the feces as
the Intact compound were 5% for 1,2,3,4-tetrachlorobenzene, 14% for 1,2,3,5-
tetrachlorobenzene and 16% for 1,2,4,5-tetrachlorobenzene. Considering the
small amount of Isomers 1n the feces through 6 days postdoslng and that some
of this fecal content may have been due to biliary excretion, 1t can be
assumed that gastrointestinal absorption of the three tetrachlorobenzene
Isomers 1s a relatively efficient process 1n rabbits (Jondorf et al., 1958).
The percentages of the administered doses recovered unchanged 1n the "gut
contents" were 0.5, 1.4 and 6.2% for 1,2,3,4-, 1,2,3,5- and 1,2,4,5-tetra-
chlorobenzene, respectively, suggesting that the chlorine positions on the
molecule may Influence absorption. Based on the mlcroanatomy of the respir-
atory epHhella, a similar absorption efficiency may be predicted for
Inhalation exposures but the efficiency of gastrointestinal absorption may
also be due to enterohepatlc recycling.
10.1.2. Distribution. The tissue distribution patterns of 1,2,4,5-tetra-
chlorobenzene 1n beagle dogs (Braun et al., 1978) and of all three tetra-
chlorobenzene Isomers 1n Chinchilla rabbits (Jondorf et al., 1958) and rats
(Chu et al., 1983; Jacobs et al., 1977) have been described. None of these
Investigators speculated on comparisons between the animal species tested
and humans.
Braun et al. (1978) administered 5 mg/kg/day of 1,2,4,5-tetrachloroben-
zene 1n the diet to 2 male and 2 female beagle dogs for 2 years. The
resulting distribution of 1,2,4,5-tetrachlorobenzene was described 1n terms
of a two-compartment pharmacoklnetlc model, with clearance rate constants
(k ) of 6.64+0.82xlO~a day"1 for plasma and 6.22+0.58x1O"3 day'1
e
for fat tissue. The half-lives for elimination from fat and plasma were 111
and 104 days, respectively. The authors concluded that steady-state was
1833A 10-2 03/15/84
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approached at a faster rate 1n fat than 1n plasma. However, the steady-
state profiles for both fat and plasma (Tables 10-1 and 10-2) appear to be
similar, and no statistically significant difference was reported. The
fatrplasma ratio (F/P) was -650 after 1 month of treatment, Indicating that
I,2,4,5-tetrachlorobenzene has a high affinity for fat. During the remain-
der of the study, F/P decreased steadily, reaching -280 by the end of the
study. Therefore, the fat was probably becoming saturated with each succes-
sive dose, and the 1,2,4,5-tetrachlorobenzene concentration In the plasma
Increased more rapidly over time than that 1n the fat. During the 20-month
observation period that followed treatment, F/P Increased rapidly, as the
available 1,2,4,5-tetrachlorobenzene 1n the plasma and other hypothetical
low affinity compartments was preferentially redistributed to the high
affinity fat compartment.
Jondorf et al. (1958) administered dosages of 500 mg/kg each of the
three tetrachlorobenzene Isomers 1n a 10% solution 1n arachls oil by stomach
tube to groups of three Chinchilla rabbits. The animals were killed 6 days
post-dosing, and the unchanged tetrachlorobenzene Isomers were detected 1n
the liver, brain, skin, depot fat, gut contents and other unspecified parts
of the body (cumulatively referred to as "rest of body"). The percentage of
the administered dose measured as unchanged Isomer for each of the above
tissues 1s presented 1n Table 10-3.
Chu et al. (1983) administered 14C-labeled 1,2,3,4-, 1,2,3,5- and
1,2,4,5-tetrachlorobenzene as a single oral dose of 1 or 10 mg/kg to male
rats, and killed the treated animals 7 days postdoslng. At the higher dose
level, 1,2,4,5-tetrachlorobenzene was observed 1n all tissues examined,
Including fat (411 ppm), skin {33 ppm), kidney (23 ppm) and liver (22 ppm);
there was no Indication 1n the abstract whether these concentrations were
1833A 10-3 03/29/84
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TABLE 10-1
Percentage of 1,2,4,5-Tetrachlorobenzene Steady-State Reached
at Specific Times 1n Fat and Plasma of Dogs*
Percentage of Steady-State Profile
Time of Exposure
(days)
10
30
90
180
365
730
Fat
5.5
16
40
64
87
98
Plasma
4.8
14
35
58
83
97
*Source: Braun et al., 1978
2 Male and 2 female beagle dogs were administered 5 mg/kg/day of 1,2,4,5-
tetrachlorobenzene 1n the diet.
1833A
10-4
03/02/84
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TABLE 10-2
Time Required to Reach Various Percentages of
1,2,4,5-Tetrachlorobenzene Steady-State In Fat and Plasma of Dogs*
Percentage of Steady State
99.9
98.0
90.0
50.0
Time
Fat
1220
691
407
122
(days)
Plasma
1418
803
473
142
*Source: Braun et al., 1978
2 Male and 2 female beagle dogs were administered 5 mg/kg/day of 1,2,4,5-
tetrachlorobenzene 1n the diet.
1833A 10-5 03/02/84
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TABLE 10-3
Unchanged Tetrachlorobenzene 1n Rabbit Tissues
6 Days After Oral Dosing (500 mg/kg)*
letrachlorobenzene
Isomer Liver
Percentage of Dose
Brain Skin
Depot
Fat
Gut
Contents
Rest of
Body
Total
1.2.3.4-
1.2.3.5-
1.2.4,5-
0.1 0
<0.5 <0.2
0.1 <0.1
2 5
5 11
10 25
0.5
1.4
6.2
2.0
5.2
6.4
10
23
48
*Source: Jondorf et al., 1958
1833A
10-6
03/02/84
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Intact compound or radioactivity. Similar tissue distribution patterns were
observed for animals given the higher doses of 1,2,3,4- or 1,2,3,5-tetra-
chlorobenzene, but tissue concentrations were much less; further detail
regarding target tissues and concentrations for these two Isomers were not
reported 1n the abstract. At the lower doses, a similar tissue distribution
pattern for all three Isomers was observed.
As reported 1n the summary of a German study, Jacobs et al. (1977)
continuously fed rats diets containing 1,2,4,5-tetrachlorobenzene (dose
level and duration not reported). Accumulation of 1,2,4,5-tetrachloroben-
zene and Us derivatives were greatest In adipose tissue. The maximum
concentrations 1n adipose tissue and blood were reached by 3 weeks after
Initiation of treatment, and steady state was attained 1n both adipose and
blood compartments by 5 weeks after Initiation of treatment.
MorHa et al. (1975d) analyzed adipose tissue samples of 15 residents of
the Tokyo metropolitan area for 1,2,4,5-tetrachlorobenzene. Residual tissue
levels of 1,2,4,5-tetrachlorobenzene ranged from 0.006-0.039 pg/g of fat,
with a mean residual tissue level of 0.019 yg/g of fat. The source and
route of exposure to 1,2,4,5-tetrachlorobenzene were not Identified.
10.1.3. Metabolism. Kohll et al. (1976a) examined the metabolic fate of
the three tetrachlorobenzene Isomers In male rabbits following a single
Intraperltoneal Injection of the compounds dissolved In vegetable oil at
dose levels of 60-75 mg/kg. The urine and feces of the treated animals were
collected for 10 days postdoslng and examined for major metabolites.
1,2,3,5-Tetrachlorobenzene was the most extensively metabolized Isomer,
yielding 2,3,4,5-, 2,3,5,6- and 2,3,4,6-tetrachlorophenol. 1,2,3,4-Tetra-
chlorobenzcne was metabolized to 2,3,4,5- and 2,3,4,6-tetrachlorophenol,
1833A 10-7 03/29/84
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while 1,2,4,5-tetrachlorobenzene yielded the single metabolite, 2,3,5,6-
tetrachlorophenol. The authors proposed corresponding arene oxides as elec-
trophlUc Intermediate metabolites of all three tetrachlorobenzene Isomers,
with the ultimate tetrachlorophenol formation from 1,2,3,5- and 1,2,3,4-
tetrachlorobenzene Involving an NIH shift of a chlorine atom. The metabo-
lism of 1,2,4,5-tetrachlorobenzene to 2,3,5,6-tetrachlorophenol can be
achieved via the 2,3,5,6-tetrachlorobenzene oxide Intermediate without an
NIH shift of a chlorine atom. Further evidence of this metabolic pathway
was provided by Ar1yosh1 et al. (1974, 1975a,b), who reported that all three
tetrachlorobenzene Isomers Increased the cytochrome P-450 enzyme activity 1n
the liver of rats, Indicating that oxldatlve metabolism with the formation
of the corresponding arene oxide Intermediate 1s a plausible pathway.
The metabolic fate of the tetrachlorobenzenes In rabbits also was
Investigated by Jondorf et al. (1958). Single doses of 500 mg/kg tetrachlo-
robenzene Isomers were given to groups of three rabbits by stomach tube 1n a
10% solution 1n arachls oil. The metabolic products detected 1n the urine
through day 6 postdoslng, as summarized 1n Table 10-4, Included tetrachloro-
phenols and the glucuronlde, ethereal sulfate and mercapturlc add conju-
gates. The authors suggested that the tetrachlorobenzenes were metabolized
via the competitive reactions Involving oxldatlve hydroxylatlon or reductive
dechlorlnatlon. In agreement with the results obtained by KohH et al
(1976a), Jondorf et al. (1958) also reported that 1,2,4,5-tetrachlorobenzene
was the least metabolized tetrachlorobenzene Isomer; 48% of the administered
dose of 1,2,4,5-tetrachlorobenzene was detected as the Intact compound 1n
the tissues of rabbits at 6 days after administration, as compared to 10%
for 1,2,3,4-tetrachlorobenzene and 23% for 1,2,3,5-tetrachlorobenzene. It
1833A 10-8 03/29/84
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CD
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TABLE 10-4
Urinary Metabolites of Tetrachlorobenzene Isomers in Rabbits 6 Days After Oral Dosing (500 mg/kg)*
Percentage of Dose (Mean Values) Excreted as
Tetrachlorobenzene
Isomer
Glucuronlde
Ethereal Sulfate
Mercapturic Add
Tetrachlorophenol
Free Total
1,2,3.4-
1.2,3,5-
1,2,4,5-
30
6
4
3
2
1
0
0
8
1.9
1.3
43
5
2.2
*Source: Jondorf et al., 1958
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was suggested by MorHa (1977) that the metabolism of 1,2,4,5-tetrachloro-
benzene via oxldatlve hydroxylatlon 1s partially Inhibited because of sterlc
factors.
Chu et al. (1983) administered single oral doses of 1 or 10 mg/kg
14C-labeled 1,2,4,5-, 1,2,3,5- and 1,2,3,4-tetrachlorobenzene each to male
rats, and killed the treated animals 7 days postdoslng. Urinary metabolites
of the tetrachlorobenzene Isomers detected Included tetrachlorophenols,
trlchlorophenols, dlhydroxylated tetrachlorobenzenes and trace amounts of
sulfur-containing metabolites; no distinction between Individual Isomers and
metabolites was made In the abstract.
The tetrachlorobenzenes have been reported as metabolites of llndane In
rats (Engst et al., 1976a), molds (Engst et al., 1979), hen pheasants,
wheat, lettuce and endives (KohH et al, 1976b,c; Saha and Burrage, 1976),
and of hexachlorobenzene 1n rats (Mehendale et al., 1975; Engst et al.,
1976a).
10.1.4. Excretion. Jondorf et al. (1958) administered single doses of 500
rng/kg each of the tetrachlorobenzene Isomers to groups of three rabbits by
stomach tube In a 10% solution 1n arachls oil. The tetrachlorobenzene
Isomers were excreted as phenols (primarily tetrachlorophenols) 1n the
urine, as Intact compound In the feces and breath and as other chloroben-
zenes In the expired air. Total excretion of the administered dose at 6
days postdoslng was 68% for both 1,2,3,4- and 1,2,3,5-tetrachlorobenzene,
and 83% for 1,2,4,5-tetrachlorobenzene. The excretion profiles for the
1somer1c tetrachlorobenzenes are summarized In Table 10-5, and the excretion
of the Intact compound 1n the expired air over 5 days postdoslng Is summar-
ized 1n Table 10-6.
1833A 10-10 03/02/84
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00
to
C*5
3»
O
I
TABI 1- 10-5
Summary of Excretion of the Isomerlc Tetrachlorobenzenes as Metabolites or as
Unchanged Compound 1n Rabbits Dosed Orally (500 mg/kg)*
Percentage of Dose Excreted as
Phenols 1n Urine Unchanged Tetrachlorobenzene 1n
Tetrachlorophenol
Isomer
1,2,3,4-
1,2,3,5-
1,2,4,5-
Tetrachlorophenols Other Feces Tissues Breath
Phenols
43 <1 5 10 8
5 5 14 23 12
2 5 16 48 2
Other
Chlorobenzenes
1n Breath
2
9
10
Total
68
68
83
*Source: Jondorf et al., 1958
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TABLE 10-6
Excretion of Unchanged Tetrachlorobenzenes 1n the
Expired A1r of Rabbits After Oral Dosing (500 mg/kg)*
Tetrachlorobenzene
Isomer
1,2,3.4-
1.2,3.5-
1,2.4.5-
Percentage
Days after
123
1.9 2.2 1.6
2.1 2.1 1.2
1.2 0.2 0.2
of Dose
Dosing
4
0.2
2.9
0
1n Expired Air
5
0
2.6
0
Total
5.9
10.9
1.6
*Source: Jondorf et al., 1958
1833A
10-12
03/29/84
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Chu et al. (1983) administered single oral doses of 1 or 10 mg/kg each
of ^C-labeled 1,2,4,5-, 1,2,3,5- and 1,2,3,4-tetrachlorobenzene to male
rats, and killed the treated animals 7 days postdoslng. Animals receiving
the higher dose of 1,2,4,5-tetrachlorobenzene were observed to excrete 16.7%
of the administered dose 1n the urine and 4.8X 1n the feces. The percentage
of the administered dose excreted 1n the urine and feces of animals dosed
with 1,2,3,5- or 1,2,3,4-tetrachlorobenzene was greater than that for those
dosed with 1,2,4,5-tetrachlorobenzene; however, actual percentages were not
reported. Excretion of the lower doses of Isomers were similar to the per-
centage values observed with the higher doses, but quantitative results were
not presented 1n the abstract.
10.1.5. Summary. No studies describing the absorption, distribution,
metabolism or excretion of 1,2,3,4-, 1,2,3,5- or 1,2,4,5-tetrachlorobenzene
following Inhalation exposure were located 1n the available literature. The
pharmacoklnetlcs of the tetrachlorobenzene Isomers following oral admini-
stration 1s well characterized In rabbits, but not 1n other animal species.
The UpophlUc characteristics of the tetrachlorobenzene Isomers would allow
efficient transepHhellal absorption at the gastrointestinal and respiratory
surfaces. Once absorbed, the tetrachlorobenzene Isomers administered orally
to rabbits was rapidly accumulated 1n fat, metabolized primarily to tetra-
chlorophenols and conjugated partly as glucuronldes and ethereal sulfates,
or eliminated unchanged 1n the expired air or feces (Jondorf et al., 1958).
No pharmacoklnetlc data were available for humans, except a report of
1,2,4,5-tetrachlorobenzene 1n adipose tissue (range of 0.006-0.039 mg/kg bw;
mean of 0.019 mg/kg bw) of 15 Tokyo residents (Morlta et al., 1975d).
Although quantitative estimates of human exposure to the tetrachlorobenzene
Isomers via air, food or drinking water were not available, based on the
1833A 10-13 03/29/84
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relatively limited Industrial use of the tetrachlorobenzene Isomers (U.S.
EPA, 1980b), human exposure may not be significant. The tetrachlorobenzene
Isomers are both ±n vivo and in vitro metabolites of the pesticides, Undane
and hexachlorobenzene (Mehendale et al., 1975; Engst et al., 1976a,b, 1979;
KohH et al, 1976b,c; Saha and Burrage, 1976); therefore, human exposure via
air, food and drinking water may occur from the environmental degradation of
these pesticides.
10.2. EFFECTS ON HUMANS
Only one ep1dem1olog1c study was available regarding the effects of the
tetrachlorobenzenes on humans. Klraly et al. (1979) examined peripheral
lymphocytes for chromosomal abnormalities 1n blood collected from Hungarian
workers engaged 1n the production of 1,2,4,5-tetrachlorobenzene. The
"normal control" group consisted of 49 nonfactory workers (ages, 26-52
years; average age, 38.2 years) who provided blood for chromosome examina-
tion at a genetic counseling clinic. The "factory employees control" group
consisted of 14 factory employees (ages, 28-47 years; average age, 35.4
years; duration of employment range of 10-30 years) not directly exposed to
the 1,2,4,5-tetrachlorobenzene manufacturing process, but with possible
Inadvertent exposure to other unspecified airborne pollutants. The "posi-
tive control" group contained 25 factory workers (ages, 31-59 years; average
age, 44.6 years) producing 1,2,4,5-tetrachlorobenzene; each had been
employed at that job for >6 months, working 8 hours/day, and wearing "Tucan-
type" face masks during work hours. Coded samples of peripheral lymphocytes
were cultured for 48 hours, and >50 metaphase cells were examined for each
sample. Factory air concentrations of 1,2,4,5-tetrachlorobenzene were not
determined.
1833A 10-14 03/29/84
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The group of workers exposed to 1,2,4,5-tetrachlorobenzene had a sig-
nificantly Increased (p<0.01) frequency of cells with <46 chromosomes when
compared with both the normal and factory employee control groups. Poly-
ploldy was observed 1n 2.94% (40 of 1360) of the mitoses examined from the
exposed group, compared with 0.59% (15 of 2523) 1n the normal control, and
2.50% (21 of 838) 1n the factory control group; statistical significance was
not Indicated. Inadvertent exposure to airborne pollutants may have
resulted 1n the relatively high percentage of polyploldy and chromosome
aberrations observed 1n the factory control group. The frequencies for
chromatld-type chromosome aberrations, labile chromosome-type aberrations
and stable chromosome-type aberrations for the three groups are listed 1n
Tables 10-7, 10-8 and 10-9, respectively. The authors concluded that
1,2,4,5-tetrachlorobenzene was mutagenlc (I.e., clastogenlc) to occupation-
ally exposed humans.
10.3. MAMMALIAN TOXICOLOGY
No animal studies on acute toxldty, subchronlc toxldty, chronic toxlc-
1ty, mutagenldty, carc1nogenc1ty or reproductive and teratogenic effects of
1,2,3,4-, 1,2,3,5- or 1,2,4,5-tetrachlorobenzene following Inhalation
exposure were located 1n the available literature. Several oral studies
describing some of the effects of the three tetrachlorobenzene Isomers In
animal species are available and are described below. A summary of sub-
chronic, chronic, reproductive and teratogenic toxldty studies on tetra-
chlorobenzenes can be found 1n Table 10-10.
10.3.1. Acute Toxldty. The oral LD for 1,2,4,5-tetrachlorobenzene
was reported to be 1035 mg/kg when given 1n sunflower oil and 2650 mg/kg
when given 1n 1.5% starch solution 1n mice and 1500 mg/kg when given 1n
1833A 10-15 03/29/84
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TABLE 10-7
Frequency of Chromat1d-type Chromosome
Aberrations 1n Peripheral Lymphocytes3
Parameter
No. of Mitoses Examined
(subjects)
Gap
Number
Percent
Isogapb
Number
Percent
Total (Gap + Isogap)
Percent
Break
Number
Percent
Isobreakb
Number
Percent
lotal (Break +• Isobreak)
Percent
Exchange
Number
Percent
Total Aberrations
Number
Percent
Normal
Control
2523 (49)
73
2.89
19
0.75
92
3.64
40
1.59
17
0.67
57
2.26
0
0
149
5.90
Factory 1
Control
838 (14)
46
5.48
2
0.23
48
5.71
26
3.10
18
2.14
44
5.24
0
0
92
10.97
, 2,4,5-Tetrachlorobenzene
Exposed
1360 (25)
81
5.95
30
2.20
111
8.15
55
4.04
32
2.35
87
6.39
2
0.15
198
14.70C
aSource: Klraly et al., 1979
blsogap and Isobreak are aberrations Involving the same location on two
chromatlds
Statistically significant difference between exposed and each of the
control groups; test and p value not specified.
1833A 10-16 03/15/84
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TABLE 10-8
Frequency of Labile Chromosome-type Aberrations*
Parameter
No. of Mitoses Examined
(subjects)
Acentric Fragment
Number
Percent
Ring Chromosome
Number
Percent
Dlcentrlc Chromosome
Number
Percent
Total
Number
Percent
Normal
Control
2523 (49)
9
0.35
0
0
0
0
9
0.35
Factory
Control
838 (14)
8
0.95
0
0
0
0
8
0.95
1 ,2,4,5-Tetrachlorobenzene
Exposed
1360 (25)
19
1.40
2
0.15
2
0.15
23
1.69
*Source: Klraly et al., 1979
1833A 10-17 03/02/84
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TABLE 10-9
Frequency of Stable Chromosome-type Aberrations3
Parameter
No. of Karyotypes Examined
Deletion
Number
Percent
Inversion
Number
Percent
Translocatlon
Number
Percent
Total
Number
Percent
Normal
Control
460
19
4.13
4
0.87
3
0.65
26
5.65
Factory
Control
144
10
6.94
1
0.69
2
1.38
13
9.02
1 ,2,4,5-Tetrachlorobenzene
Exposed
237
27
11.39
4
1.68
5
2.10
36
15.18&
aSource: Klraly et al., 1979
bStat1st1cally significant difference between exposed and normal controls
and factory controls (p<0.1, test not specified).
1833A 10-18 03/02/84
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TABLE 10-10
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Species Route Dose
Rat oral 0.5-500 mg/kg
of diet
1,2,4,5-TeCB
Rat oral 0.001, 0.005,
0.05 mg/kg/day
1,2,4,5-TeCB
Rabbit oral 0.001, 0.005,
0.05 mg/kg/day
1.2,4,5-TeCB
Rat oral 75 mg/kg/day
T.2,4,5,-TeCB
Dog oral 5 mg/kg/day
1,2,4,5-TeCB
Pregnant rats oral 50, TOO,
200 mg/kg/day
T,2,4,5-TeCB
Pregnant rats oral 50, 100,
200 mg/kg/day
1,2.3,4-TeCB
Pregnant rats oral 50, 100,
200 mg/kg/day
1,2,3,5-TeCB
1,2,4,5-TeCB = 1 ,2.4.5-tetrachlorobenzene
Summary of ToxIcHy
Duration
28 or 90 days
8 mo
8 mo
2 mo
2 yr exposure,
22 mo recovery
days 6-15 of
gestation
days 6-15 of
gestation
days 6-15 of
gestation
Studies on Tetrachlorobenzenes
Effects
Increased liver and kidney weights and
hlstologlcal changes In liver and kidneys;
Increases 1n MFO activity, serum cholesteroT
values
No effects observed 1n 0.001 mg/kg/day dose
group; 0.005 and 0.05 mg/kg/day doses caused
disruption 1n conditioned reflexes, Increases
In liver weight coefficients and decrease In
serum SH groups
No effect observed 1n 0.001 mg/kg/day dose
group; 0.05 mg/kg dose caused disorder of
liver glycogen formation, altered serum SH
group levels, Increase In blood hemoglobin
and peripheral retlculocyte levels
Altered biochemical parameters Indicating
changes In hepatic and hematopo1t1c homeo-
stasls
No controls used; elevated SAP and total
b1!1rub1n, returned to normal range 3 mo
after exposures ended
High-dose lethal to 9/10 of treated dams;
organ weight changes, elevated serum
cholesterol and liver metabolism enzymes,
no Indication of those changes were dose-
related
Induced maternal toxIcHy and Increased
lethality of pups at 200 mg/kg/day
Increased lethality 1n 200 mg/kg/day group
pups; one pup malformed and minor chondro-
genic delay 1n other pups
Reference
VUleneuve et al. ,
1983
Fomenko, 1965
Fomenko, 1965
Fomenko. 1965
Braun et al., 1978
Ruddlck et al., 1981
Ruddlck et al., 1981
Ruddlck et al.. 1981
1,2,3,4-TeCB = 1,2,3,4-tetrachlorobenzene
1,2,3,5-TeCB = 1,2.3.5-tetrachlorobenzene
-------
apparently sunflower oil 1n rats and rabbits (Fomenko, 1965). Vllleneuve et
al. (1983) reported an LD... range of -1200-3000 mg/kg 1n rats for the
bu
three tetrachlorobenzene Isomers with 1,2,3,4-tetrachlorobenzene > 1,2,3,5-
tetrachlorobenzene > 1,2,4,5-tetrachlorobenzene; further details regarding
doses and effects were not provided 1n the abstract.
R1m1ngton and Zlegler (1963) administered relatively large dietary doses
of 1,2,3,4-tetrachlorobenzene at a level of 660 mg/kg/day for 10 days or
1,2,4,5-tetrachlorobenzene at a level of 905 mg/kg/day for 5 days to rats.
1,2,3,4-Tetrachlorobenzene Induced weight loss, nonnecrotlc liver cell
degeneration and an Increase 1n porphyrln and hemoglobin metabolism, while
the only effect reported for 1,2,4,5-tetrachlorobenzene was nonnecrotlc
liver cell degeneration.
No studies were available regarding the dermal toxldty or sens1t1zat1on
reactions of the three tetrachlorobenzene Isomers.
10.3.2. Subchronlc Toxldty. As reported 1n an abstract, Vllleneuve et
al. (1983) administered dietary concentrations of 1,2,3,4-, 1,2,3,5- and
1,2,4,5-tetrachlorobenzene ranging from 0.5-500 ppm to both sexes of rats
for 28 or 90 days. Administration of 1,2,4,5-tetrachlorobenzene resulted 1n
Increased kidney and liver weights, Increased mixed function oxldase activi-
ties, Increased serum cholesterol values, moderate to marked histologlcal
liver changes 1n both sexes, and marked histologlcal kidney changes 1n
males. The authors concluded that 1,2,4,5-tetrachlorobenzene was the most
toxic tetrachlorobenzene Isomer when administered 1n the diet to rats, and
that males appeared to be more susceptible than females. The authors did
not specify the number or strain of animals used, 1f the effects observed
were dose-related or only seen at the higher dose(s), the severeness of
effects, or the type of histologlcal changes observed.
1833A 10-20 03/29/84
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Fomenko (1965) examined the subchronlc tox1c1ty of 1,2,4,5-tetrachloro-
benzene In rats and rabbits. Both species of animals were given the com-
pound dally by gavage 1n vegetable oil at dose levels of 0, 0.001, 0.005 or
0,05 mg/kg for 8 months. No treatment-related effects were observed 1n
either rats or rabbits at the 0.001 mg/kg dose level. Doses of 0.005 or
0.05 mg/kg to rats Induced a disruption of conditioned reflexes, Increased
liver weight coefficients, and decreased blood serum SH groups, while
Increased organ ascorbic add was seen only 1n those rats given 0.05 mg/kg;
the author did not Indicate the statistical significance of these effects.
Rabbits given 0.005 mg/kg had a transient disorder of liver glycogen forma-
tion and a statistically significant (p=0.05) change In blood serum SH
groups during the last month of treatment. At the 0.05 mg/kg dose level,
rabbits were observed to have a disorder of liver glycogen formation during
the sixth month of treatment, Increased serum blood SH groups 1n the fifth
month that was followed by a decrease, a statistically significant (p=0.05)
Increase 1n the blood hemoglobin level during the third month of treatment,
an Increased level of peripheral retlculocytes at the end of the last month
of treatment, and an Increased retention of an Intravenous galactose load by
6 months of treatment.
In a 2-month oral study, rats were given dally doses of 0 or 75 mg/kg
1,2,4,5-tetrachlorobenzene In vegetable oil by gavage (Fomenko, 1965). No
treatment-related hlstologlc changes were observed, but several biochemical
parameters were affected, Indicating changes 1n hepatic and hematopoletlc
homeostasls. The blood chollnesterase activity Increased significantly
(p=0.01), and the prothrombln Index dropped by -1/3 of the control value (p
not reported). In addition, the number of peripheral retlculocytes
decreased significantly (p=0.02) but then Increased, the serum potassium
1833A 10-21 03/02/84
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levels were reduced (p not reported), and the number of peripheral large-
diameter erythrocytes was Increased (p not reported). The Incidence of
erythemla was significantly Increased (p=0.01). At cessation of treatment,
statistically significant (p=0.01) observed effects Included a decrease 1n
serum SH groups, adrenal hypertrophy and decreased adrenal ascorbic add.
10.3.3. Chronic Tox1c1ty. Braun et al. (1978) fed two beagle dogs of each
sex diets containing doses of 5 mg/kg/day 1,2,4,5-tetrachlorobenzene for 2
years, and then observed them for a 20-month recovery period. The primary
goal of the study was to determine the uptake and elimination kinetics for
plasma and fat; therefore, no concurrent control animals were used. Histor-
ical control data, however, suggested that the elevations of serum alkaline
phosphatase and total bH1rub1n after 24 months of administration were
related to treatment. The elevated clinical chemistry values returned to
the normal range of values for the historical controls at 3 months Into the
20-month recovery period. Gross and hlstopathological examinations of
tissues done after the recovery period did not reveal any treatment-related
morphological changes 1n the animals. This study cannot substantiate either
a no-observed-effect level (NOEL) or a lowest-observed-effect level (LOEL),
because concurrent controls were not used, the number of treated animals
used was small, and only one dose level was tested.
10.3.4. Mutagen1c1ty. Klraly et al. (1979) reviewed the chromosomal
effects of 1,2,4,5-tetrachlorobenzene 1n Hungarian workers and concluded
that 1,2,4,5-tetrachlorobenzene is mutagenic 1n occupationally-exposed
humans. A more accurate conclusion from this data Is that 1,2,4,5-tetra-
chlorobenzene is clastogenlc in the exposed humans. This paper was
discussed 1n detail in Section 10.2.
1833A 10-22 03/29/84
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ParacM and Lovenyak (1981) reported that 1,2,4,5-tetrachlorobenezene did
not Induce an Increased frequency of sex-linked recessive lethals In Droso-
phlla melanogaster exposed by larval feeding at a dose less than the LC,-n
(actual dose not reported). Because only an abstract of the original paper
was evaluated, rather than the paper Itself, there was no Information
regarding the number of chromosomes assayed at each dose nor the doses
used. This Information 1s essential before any conclusions can be made as
to whether or not 1,2,4,5-tetrachlorobenzene can Induce sex-linked recessive
lethal mutations 1n Drosophlla.
1,2,3,5- and 1,2,4,5-tetrachlorobenzene were tested for mutagenldty by
plate Incorporation with Salmonella typh1mur1um strains TA98, TA100, TA1535,
TA1537 and TA1538 at five unspecified dose levels (Lawlor et al., 1979).
Both Isomers gave negative results 1n the reverse mutation assay either 1n
the presence or absence of an S-9 metabolic activation system from rats
pretreated with Aroclor 1254. Because these results were reported In an
abstract, Insufficient experimental detail was provided to permit a critical
evaluation of the data.
10.3.5. CareInogenlcity. Pertinent data regarding the carclnogenldty of
1,2,3,4-, 1,2,3,5- and 1,2,4,5-tetrachlorobenzene were not located 1n the
available literature.
10.3.6. Reproductive and Teratogenlc Effects. As reported In an abstract,
Ruddlck et al. (1981) administered 1,2,3,4-, 1,2,3,5- and 1,2,4,5-tetrachlo-
robenzene via gavage (vehicle not reported) at dose levels of 0, 50, 100 or
200 mg/kg to pregnant rats (10/dose level) on days 6 through 15 of gesta-
tion. 1,2,4,5-Tetrachlorobenzene was the most toxic Isomer, Inducing
lethality 1n 9 of 10 treated dams at the 200 mg/kg level. A dose-related
accumulation of compound residue was seen 1n dams and offspring with all
1833A 10-23 03/15/84
-------
three Isomers, but was greatest 1n those animals given 1,2,4,5-tetrachloro-
benzene. Other toxldty effects observed In dams treated with 1,2,4,5-
tetrachlorobenzene Included organ weight changes and significantly elevated
serum cholesterol, liver am1nopyr1ne-N-demethylase and hepatic aniline
hydroxylase levels; 1t was unclear from the abstract whether these changes
were dose-related or occurred at a single dose level. 1,2,3,4-Tetrachloro-
benzene also Induced maternal toxldty, manifested 1n a significantly
lowered platelet count at the 200 mg/kg level. Fetotox1c1ty, as Indicated
by Increased lethality of pups, was observed at the 200 mg/kg level of
1,2,3,4- and 1,2,3,5-tetrachlorobenzene. One malformed pup and minor chon-
drogenlc delay were seen among the offspring of dams given 1,2,3,5-tetra-
chlorobenzene.
10.4. INTERACTIONS
Tetrachlorobenzene 1s capable of Inducing the NADPH-dependent cytochrome
P-450 metabolizing enzymes, which are nonspecific for natural and xenoblotlc
substrates (Ar1yosh1 et al., 1974, 1975a,b). The substrate may either be
detoxified by such metabolism or become more hazardous (toxlfled) 1f con-
verted to a reactive Intermediate capable of binding to critical Intracellu-
lar macromolecules. In Itself, P-4SO Induction Is not a disadvantage, but
H may become one when substrates are activated during metabolism (Neal,
1980). Thus, exposure to tetrachlorobenzene may enhance the toxlclty of a
compound that normally would be Innocuous. No studies were available,
however, to demonstrate the Interaction of tetrachlorobenzene with other
compounds.
10.5. SUMMARY
No animal studies on pharmacoklnetlcs, acute toxldty, subchronlc
toxldty, chronic toxldty, miltagenlcity, cardnogenlclty or reproductive
1833A 10-24 03/29/84
-------
and teratogenlc effects of 1,2,3,4-, 1,2,3,5- or 1,2,4,5-tetrachlorobenzene
following Inhalation exposure were located 1n the available literature.
Tetrachlorobenzenes are I1p1d-soluble compounds that bloaccumulate 1n
the fat of aquatic and terrestrial organisms. Although the Isomers were
preferentially distributed to adipose tissue, they did not cross the blood-
brain barrier of rabbits. Some Tokyo residents were found to have 1,2,4,5-
tetrachlorobenzene (mean of 0.019 mg/kg bw) 1n their adipose tissue.
The metabolism of the tetrachlorobenzene Isomers apparently follows
aromatic hydroxylatlon to tetrachlorophenols with an arene oxide Intermedi-
ate. Rabbits and rats treated with the tetrachlorobenzene Isomers excreted
unchanged compound 1n expired air and feces; the urine contained tetrachlo-
rophenols, trlchlorophenols, dlhydroxylated tetrachlorobenzenes, glucuron-
1des and ethereal sulfates.
The tetrachlorobenzenes have been reported as metabolites of Undane 1n
rats, molds, hen pheasants, wheat, lettuce and endives, and of hexachloro-
benzene 1n rats.
Chromosome aberrations were observed 1n the lymphocytes of Hungarian
workers producing 1,2,4,5-tetrachlorobenzene; no airborne concentrations or
exposures were determined.
The only mammalian toxicology data available for tetrachlorobenzenes are
the result of oral exposures. The oral L05_ for 1,2,4,5-tetrachloroben-
zene was reported as 1035 mg/kg 1n mice and 1500 mg/kg 1n rats and rabbits
when administered 1n sunflower oil and 2650 mg/kg 1n mice when administered
1n 1.5% starch solution. Subchronlc oral exposure of rats and rabbits to
1,2,4,5-tetrachlorobenzene resulted 1n statistically significant effects on
biochemical parameters, Including retlculocytosls, Increased blood cholln-
esterase activity, erythremla and an Indication that glycogen formation was
1833A 10-25 03/15/84
-------
Impeded; at higher doses of 1,2,4,5-tetrachlorobenzene, rats also had
Increased kidney and liver weights, and renal and hepatic hlstologlc changes.
Reversible effects on serum alkaline phosphatase and total b1!1rub1n
were reported 1n dogs given 5 mg/kg/day 1,2,4,5-tetrachlorobenzene 1n the
diet for 2 years.
1,2,4,5-Tetrachlorobenzene was not mutagenlc 1n the sex-linked recessive
lethal assay with Drosophlla roelanogaster. However, because only an
abstract of the Drosophlla study was available, experimental details were
too sparse to permit a critical evaluation of this negative result. Both
1,2,3,5- and 1,2,4,5-tetrachlorobenzene were negative In the reverse muta-
tion assay with Salmonella typh1reur1um strains TA98, TA100, TA1535, TA1537
and TA1538. These results were reported 1n an abstract with Insufficient
experimental detail. Also, a negative result 1n the Salmonella assay with
chlorinated compounds 1s not unexpected.
No Information was available regarding the carc1nogen1c1ty of any of the
three tetrachlorobenzene Isomers In either animals or humans.
The tetrachlorobenzene Isomers Induced appreciable maternal toxldty,
mild fetotoxlclty and negligible teratogenlclty 1n rats following oral
administration.
1833A 10-26 03/15/84
-------
r/EPA
United States
Environmental Protection
Agency
Office of Health and
Environmental Assessment
Washington DC 20460
EPA-600/8-84-015A
April 1984
External Review Draft
Research and Development
Health Assessment
Document for
Chlorinated
Benzenes
Part 2 of 2
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.
-------
EPA-600/8-84-015A
April 1984
External Review Draft
DRAFT
Do not cite or quote
HEALTH ASSESSMENT DOCUMENT
FOR
CHLORINATED BENZENES
Part 2 of 2
Notice
This document 1s a preliminary draft. It has not been
formally released by EPA and should not at this stage be
construed to represent Agency policy. It 1s being circu-
lated for comment on Us technical accuracy and policy Im-
plications.
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Office of Health and Environmental Assessment
Environmental Criteria and Assessment Office
Cincinnati, Ohio 45268
Project Manager: W. Bruce Pelrano
-------
DISCLAIMER
This report 1s 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.
NOTE
For Information concerning this document, please contact the project
manager, W. Bruce Pelrano (513/684-7573) of the Environmental Criteria and
Assessment Office, Cincinnati, OH 45268.
11
-------
PREFACE
The Office of Health and Environmental Assessment of the Office of
Research and Development has prepared this Health Assessment Document (HAD)
on chlorinated benzenes at the request of the Office of Air Quality, Plan-
ning and Standards. The chlorinated benzenes are a group of 12 chlorinated
cyclic aromatic compounds which are currently being studied by the Environ-
mental Protection Agency (EPA) to determine 1f they should be regulated as
hazardous air pollutants under the Clean A1r Act.
In the development of this assessment document, the scientific litera-
ture has been searched and Inventoried, key studies have been reviewed and
evaluated and summaries and conclusions have been directed at Identifying
the health effects from exposure to the various chlorinated benzenes. At
several stages 1n the HAD development process, the chlorinated benzenes
document has been reviewed for scientific and technical accuracy. These
peer reviews have been by scientists from Inside and outside the EPA.
Observed effect levels and dose-response relationships are discussed where
appropriate 1n order to Identify the critical effect and to place adverse
health responses 1n perspective with observed environmental levels.
111
-------
AUTHORS, CONTRIBUTORS, AND REVIEWERS
The EPA Office of Health and Environmental Assessment (OHEA) was responsible
for the preparation of this draft health assessment document. The OHEA
Environmental Criteria and Assessment Office (ECAO-Cincinnati) had overall
responsibility for coordination and direction of the document preparation and
production effort (W. Bruce Peirano, Project Manager, Jerry F. Stara, Director,
ECAO-Cincinnati).
The participating members of the Environmental Criteria and Assessment
Office-Cincinnati, Ohio are:
W. Bruce Peirano, M.S.*
L. Erdreich, Ph.D.
H. Ball, M.S
C. DeRosa, Ph.D.
R. Hertzberg, Ph.D.
J. Risher, M.S.
S. Lutkerihoff, B.S.
D. Mukerjee, M.Sc., Ph.D.
J. Orme, M.S.
J. F. Stara, D.V.M.; D.S., Director
D. Reisman, M.En.
R. Bruins, M.S.
W. Pepelko, Ph.D.
C. Mullin, M. En.
F. Mink, Ph.D.
M. Dourson, Ph.D.
B. Farren, B.S.
D. Basu, Ph.D., Syracuse Research Corp.*
M. Neal, Ph.D., Syracuse Research Corp.*
S. Que Hee, Ph.D., Univ. of Cincinnati *
The OHEA Carcinogen Assessment Group (GAG) was responsible for preparation
of the sections on carcinogenicity. Participating members of the CAG are listed
below:
Roy E. Albert, M.D. (Chairman) Charalingayya B. Hiremath, Ph.D.
Elizabeth L. Anderson, Ph.D.
Larry D. Anderson, Ph.D.
Steven Bayard, Ph.D.
David L. Bayliss, M.S.
Chao W. Chen, Ph.D.*
Herman J. Gibb, B.S., M.P.H.
Bernard H. Haberman, D.V.M., M.S.
James W. Holder, Ph.D.
Robert E. McGaughy, Ph.D.*
Jean C. Parker, Ph.D.
Dharm V. Singh, D.V.M., Ph.D.
Todd W. Thorslund, Sc.D.
Muriel M. Lipjman, Ph.D. (Consultant)*
The OHEA Reproductive Effects Assessment Group (REAG) was responsible for
the preparation of the sections on mutagenicity. Participating members of
the REAG are listed below:
John R. Fowle III, Ph.D.
Ernest R. Jackson, M.S.
David Jacobson-Kram, Ph.D.
Casey Jason, M.D.
K. S. Lavappa, Ph.D.
Sheila L. Rosenthal, Ph.D.*
Carol N. Sakai, Ph.D.
Vicki Vaughan-Dellarco, Ph.D.
Peter E. Voytek, Ph.D. (Director)
* Authors
i v
-------
The following people also contributed to the development of this
document:
David Dellarco EPA Office of Toxic Substances
Linda S. Erdreich ECAO-Cincinnati
Charles H. Nauman OHEA Exposure Assessment Group
David J. Reisman ECAO-Cincinnati
Phil Wirdzek EPA Office of Toxic Substances
The following individuals were asked to review earlier drafts of this
document:
George T. Bryan University of Wisconsin
Derek J. Cripps University of Wisconsin
Erma Durden ECAO-Cincinnati
Erdogan Erturk University of Wisconsin
Richard W. Lambrecht University of Wisconsin
Carl R. Morris EPA Office of Toxic Substances
Henry A. Peters University of Wisconsin
James Withey Food Directorate, Canada
The following members of the ECAO-Cincinnati Technical Services Staff
were responsible for document production:
Cynthia Cooper Karen Mann
Patricia Daunt Judith Olsen
Cindy Fessler Bette Zwayer
-------
CHLORINATED BENZENES PEER REVIEW PANEL MEMBERS
July 25-26, 1983 Cincinnati, Ohio
Chairman:
W. Bruce Pelrano, ECAO-CIN
Julian B. Andelman
Dlpak Basu
Gary P. Carlson
Herbert H. Cornish
Fred Coulston
Diane Courtney
David Dellarco
Chris DeRosa
Chris Dlppel
Linda S. Erdrelch
Charlie Hlremath
Muriel M. Llppman
Debdas Mukerjee
Albert Munson
Chuck H. Nauman
M1ke Neal
William E. Pepelko
Shane Que Hee
Martha J. Radlke
David J. Relsman
John F. Rlsher
Sheila L. Rosenthal
Jerry F. Stara
Norman M. Trleff
Phil Wlrdzek
Members
University of Pittsburgh
Syracuse Research Corporation
Purdue University
University of Michigan
Coulston International Corporation
EPA, HERL-RTP
EPA, OTS, Washington, DC
University of Maine
Dynamac Corporation
EPA, ECAO-CIN
EPA, CAG, Washington, DC
ERNACO, Inc.
EPA, ECAO-CIN
Medical College of Virginia
EPA, EAG, Washington, DC
Syracuse Research Corporation
EPA, ECAO-CIN
University of Cincinnati College of Medicine
University of Cincinnati College of Medicine
EPA, ECAO-CIN
EPA, ECAO-CIN
EPA, REAG, Washington, DC
EPA, ECAO-CIN
University of Texas Medical Branch
EPA, OTS, Washington, DC
VI
-------
TABLE OF CONTENTS
1. INTRODUCTION 1-1
2. SUMMARY AND CONCLUSIONS 2-1
2.1. SUMMARY 2-1
2.1.1. Properties, Production and Use 2-1
2.1.2. Environmental Levels, Transport and Fate 2-2
2.1.3. Ecological Effects 2-4
2.1.4. Pharmacok1net1cs 2-5
2.1.5. Effects on Humans 2-10
2.1.6. Mammalian Toxicology 2-12
2.2. CONCLUSIONS 2-20
2.3. NEEDS FOR FUTURE RESEARCH 2-20
3. PHYSICAL AND CHEMICAL PROPERTIES/ANALYTICAL METHODOLOGY 3-1
3.1. SYNONYMS, TRADE NAMES AND IDENTIFICATION NUMBERS 3-1
3.2. PHYSICAL AND CHEMICAL PROPERTIES 3-1
3.3. ANALYTICAL METHODOLOGY 3-15
3.3.1. Chemical Analysis 1n A1r 3-15
3.3.2. Chemical Analysis 1n Water 3-18
3.3.3. Chemical Analysis 1n Soil, Sediment and Chemical
Waste Disposal Site Samples 3-19
3.3.4. Chemical Analysis 1n F1sh and Other Foods 3-20
3.4. SUMMARY 3-23
4. PRODUCTION, USE AND ENVIRONMENTAL LEVELS 4-1
4.1. PRODUCTION 4-1
4.2. USE 4-5
4.3. SOURCE AND ENVIRONMENTAL LEVELS 4-5
4.3.1. Levels 1n A1r 4-12
4.3.2. Water 4-18
4.3.3. Food 4-26
4.3.4. Soil and Sediments 4-28
4.3.5. Human Tissue Residues 4-29
4.4. RELATIVE SOURCE CONTRIBUTIONS TO TOTAL EXPOSURE 4-34
4.4.1. A1r 4-36
4.4.2. Water 4-36
4.4.3. Food 4-38
4.5. SUMMARY 4-38
VI I
-------
Page
5. ENVIRONMENTAL TRANSPORT AND FATE 5-1
5.1. TRANSPORT 5_1
5.1.1. A1r 5_1
5.1.2. Water ' 5.2
5.1.3. Soil 5_4
5.2. FATE 5-7
5.2.1. A1r 5-7
5.2.2. Water 5-8
5.2.3. Soil 5-10
5.3. BIOCONCENTRATION, BIOACCUMULATION AND BIOMAGNIFICATION. . . 5-13
5.4. SUMMARY 5-19
6. ECOLOGICAL EFFECTS 6-1
6.1. EFFECTS ON THE AQUATIC ENVIRONMENT 6-1
6.1.1. Effect on Freshwater and Marine Fish 6-1
6.1.2. Effect on Aquatic Crustaceans 6-14
6.1.3. Embryotoxlc and Reproductive Effects 6-16
6.1.4. Effect on Aquatic Plants 6-24
6.1.5. Residues 6-30
6.2. EFFECTS ON NONAQUATIC ENVIRONMENTS 6-34
6.2.1. Plants 6-34
6.2.2. Insects 6-35
6.2.3. Birds 6-37
6.2.4. Residues 6-38
6.3. SUMMARY 6-39
7. MONOCHLOROBENZENE 7-1
7.1. PHARMACOKINETICS 7-1
7.1.1. Absorption 7-1
7.1.2. Distribution 7-1
7.1.3. Metabolism 7-2
7.1.4. Excretion 7-5
7.1.5. Summary 7-10
7.2. EFFECTS ON HUMANS 7-10
VI I I
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Page
7.3. MAMMALIAN TOXICITY 7-12
7.3.1. Acute ToxUHy 7-12
7.3.2. Subchronlc Toxlclty 7-15
7.3.3. Chronic ToxIcHy 7-23
7.3.4. MutagenlcHy 7-24
7.3.5. Cardnogenldty 7-24
7.3.6. Reproductive and Teratogenlc Toxlclty 7-31
7.4. INTERACTIONS 7-31
7.5. SUMMARY 7-32
8. DICHLOROBENZENES 8-1
8.1. PHARMACOKINETICS 8-1
8.1.1. Absorption 8-1
8.1.2. Distribution. . 8-3
8.1.3. Metabolism 8-6
8.1.4. Excretion 8-8
8.1.5. Summary 8-9
8.2. EFFECTS ON HUMANS 8-10
8.2.1. Occupational Studies 8-10
8.2.2. Case Studies 8-11
8.2.3. Summary 8-17
8.3. MAMMALIAN TOXICOLOGY 8-17
8.3.1. Acute Toxlclty 8-17
8.3.2. Subchronlc Toxlclty 8-22
8.3.3. Chronic Toxlclty 8-32
8.3.4. MutagenlcHy 8-33
8.3.5. Cardnogenldty 8-34
8.3.6. Reproductive and Teratogenlc Toxlclty 8-39
8.4. INTERACTIONS 8-39
8.5. SUMMARY 8-40
9. TRICHLOROBENZENES 9-1
9.1. PHARMACOKINETICS 9-1
9.1.1. Absorption 9-1
9.1.2. Distribution 9-2
9.1.3. Metabolism 9-2
9.1.4. Excretion 9-6
9.1.5. Summary 9-8
9.2. EFFECTS IN HUMANS 9-9
IX
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Page
9.3. MAMMALIAN TOXICOLOGY 9.9
9.3.1. Acute Tox1c1ty 9.9
9.3.2. Subchronlc ToxIcHy 9-14
9.3.3. Chronic ToxIcHy 9-23
9.3.4. MutagenlcHy 9-24
9.3.5. CardnogenlcHy 9-25
9.3.6. Reproductive and Teratogenlc ToxIcHy 9-26
9.4. INTERACTIONS 9-28
9.5. SUMMARY 9-28
10. TETRACHLOROBENZENES 10-1
10.1. PHARMACOKINETICS 10-1
10.1.1. Absorption 10-1
10.1.2. Distribution 10-2
10.1.3. Metabolism 10-7
10.1.4. Excretion 10-10
10.1.5. Summary 10-13
10.2. EFFECTS ON HUMANS 10-14
10.3. MAMMALIAN TOXICOLOGY 10-15
10.3.1. Acute Toxldty 10-15
10.3.2. Subchronlc ToxIcHy 10-20
10.3.3. Chronic ToxIcHy 10-22
10.3.4. MutagenlcHy 10-22
10.3.5. CardnogenlcHy 10-23
10.3.6. Reproductive and Teratogenlc Effects 10-23
10.4. INTERACTIONS 10-24
10.5. SUMMARY 10-24
11. PENTACHLOROBENZENE 11-1
11.1. PHARMACOKINETICS 11-1
11.1.1. Absorption 11-1
11.1.2. Distribution 11-2
11.1.3. Metabolism 11-7
11.1.4. Excretion 11-11
11.1.5. Summary 11-13
11.2. EFFECTS ON HUMANS 11-13
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Page
11.3. MAMMALIAN TOXICOLOGY 11-13
11.3.1. Acute Toxldty 11-13
11.3.2. SubchronU ToxUHy 11-16
11.3.3. Chronic Toxldty 11-18
11.3.4. MutagenlcHy 11-19
11.3.5. CardnogenlcHy 11-19
11.3.6. Reproductive and Teratogenlc Toxldty 11-19
11.4. INTERACTIONS 11-26
11.5. SUMMARY 11-26
12. HEXACHLOROBENZENE 12-1
12.1. PHARMACOKINETICS 12-1
12.1.1. Absorption 12-1
12.1.2. Distribution 12-3
12 1.3. Metabolism 12-16
12.1.4. Excretion 12-20
12.1.5. Summary 12-27
12.2. EFFECTS ON HUMANS 12-29
12.2.1. Ep1dem1olog1c Studies 12-29
12.2.2. Accidental Ingestlon 1n Turkey 12-32
12.2.3. Summary 12-37
12.3 MAMMALIAN TOXICOLOGY 12-40
12.3.1. Acute Toxldty 12-40
12.3.2. Subchronlc Toxldty 12-42
12.3.3. Chronic Toxldty 12-56
12.3.4. MutagenlcHy 12-59
12.3.5. CardnogenlcHy 12-60
12.3.6. Reproductive and Teratogenlc Effects 12-125
12.4. INTERACTIONS 12-131
12.5. SUMMARY 12-134
13. OVERVIEW OF EFFECTS OF MAJOR CONCERN 13-1
13.1. PRINCIPAL EFFECTS AND TARGET ORGANS 13-1
13.2. ANIMAL TOXICITY STUDIES MOST USEFUL FOR HEALTH
ASSESSMENT AND ESTIMATED TOXICITY THRESHOLDS 13-5
13.2.1. Animal Toxldty Studies 13-5
13.2.2. Estimated Toxldty Thresholds 13-31
13.3. CARCINOGENICITY STUDIES 13-31
13.4. HUMAN STUDIES 13-39
XI
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Page
13.5. FACTORS INFLUENCING HEALTH HAZARD ASSESSMENT 13-40
13.5.1. Exposure 13-40
13.6. REGULATIONS AND STANDARDS 13-45
13.6.1. Occupational Standards 13-45
13.6.2. Transportation Regulations 13-51
13.6.3. Solid Waste Regulations 13-52
13.6.4. Food Tolerances 13-54
13.6.5. Water Regulations 13-54
13.6.6. A1r Regulations 13-55
14. REFERENCES 14-1
APPENDIX A: Comparison Among Different Extrapolation Models A-l
XI I
-------
LIST OF TABLES
No. Title Page
3-1 Synonyms, Trade Names and Identification Numbers of the
Chlorinated Benzenes 3-3
3-2 Physical Properties of the Chlorinated Benzenes 3-7
3-3 Vapor Pressures and Vapor Densities of the Chlorinated
Benzenes 3-8
3-4 Reported Composition of Commercial 1,2-D1chlorobenzene. . . . 3-11
4-1 United States Production of Chlorinated Benzenes for
Selected Years 4-2
4-2 U.S. Producers and Estimated Annual Production Capacities
(1983) of Chlorobenzenes 4-6
4-3 A Summary of the Uses of the Chlorinated Benzenes 4-8
4-4 Estimated Quantities of Chlorobenzenes Lost During
Manufacture, and to the Environment Compared with
Total Production 1n 1983 4-9
4-5 Estimated Quantities of Hexachlorobenzene (HCB) In
Industrial Wastes and Byproducts 1n 1972 4-11
4-6 Chlorinated Benzene Levels 1n Ambient A1r from
Different Locations 1n the U.S 4-13
4-7 Concentrations of Chlorinated Benzenes at Three Sites .... 4-16
4-8 Overall and Site-Specific Mean Atmospheric Levels of
Chlorobenzenes throughout the United States 4-17
4-9 Atmospheric Levels of Hexachlorobenzene Around Selected
Industrial Plants 4-19
4-10 Chlorinated Benzenes 1n Surface Water 4-20
4-11 Chlorobenzene Concentrations 1n Drinking Water from
Ontario, Canada ...... 4-24
4-12 Frequency and Range of Concentrations of Chlorinated
Benzenes Pollutants 1n Industrial Wastewaters 4-27
4-13 Chlorinated Benzene Residues 1n Human Adipose Tissue 4-30
4-14 Chlorinated Benzenes 1n the Blood of Nine Residents of
Love Canal 1n Niagara Falls, New York 4-33
XIII
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No. Title Page
4-15 Chlorinated Benzenes 1n the Breath and Urine of Nine
Residents of Love Canal 1n Niagara Falls, New York 4-35
4-16 Estimated Yearly Exposure to Several Chlorinated Benzenes
Via Inhalation 4-37
5-1 Predicted Transport and Fate of Chlorinated Benzenes
Released from Landfills and Lagoons 5-5
5-2 Transport of Chlorinated Benzenes 1n Sandy Soil 5-6
5-3 Estimated Atmospheric Residence Time and Dally Loss Rates
for Several Chlorinated Benzenes. 5-9
5-4 Aqueous B1odegradab1l1ty Studies of Chlorinated Benzenes. . . 5-11
5-5 Octanol/Water Partition Coefficients, B1oconcentrat1on
Factors and Biological Half-lives for Chlorinated Benzenes
1n F1sh 5-15
5-6 B1oconcentrat1on Factor and Slope of the Elimination Curve
for Gupples (PoeclHa retlculata) Exposed to Six Chlorinated
6-1
6-2
6-3
6-4
6-5
6-6
6-7
6-8
6-9
Benzenes
Acute Tox1c1ty Data for F1sh Species Exposed to Chlorinated
Benzenes
Chronic Toxldty Values of Chlorinated Benzenes 1n F1sh . . .
Bloconcentratlon Factors of Some Chlorinated Benzenes
1n Two F1sh Species ...
Acute Toxldty Data for Crustaceans Exposed to Chlorinated
Benzenes
Embryo-Larval Toxldty of Monochlorobenzene to Goldfish,
Largemouth Bass and Rainbow Trout In Soft and Hard Water. . .
Results of 1 ,2,4,5-Tetrachlorobenzene Tests with Embryo
to Juvenile Sheepshead Minnows In Continuous-Flow Natural
Seawater. ....
Adult Llfespan and Reproductive Performance of Brine
Shrimp Exposed to 1 ,3,5-Tr1chlorobenzene
Acute Toxldty Data for Aquatic Algae Exposed to
Chlorinated Benzenes
Chlorinated Benzene Concentrations (yg/1) 1n Water and
Sediment
5-18
6-2
6-12
6-15
6-17
6-21
6-23
6-25
6-26
6-31
XI V
-------
No. Title Page
6-10 Chlorinated Benzene Concentrations 1n a Variety of Marine
Species 6-32
6-11 Emergence of Adult HousefHes 8 Days Following Exposure of
Pupae to "Saturation Concentration" of DUhlorobenzene
Vapors 6-36
6-12 Chlorinated Benzene Residues 1n Bird Eggs 6-40
7-1 Percentage of Isomers of Chlorophenol from Metabolism
of Monochlorobenzene 7-4
7-2 Species Variation 1n Urinary Metabolites of 1*C-Mono-
chlorobenzene 7-9
7-3 Acute Toxldty of Monochlorobenzene 7-14
7-4 Summary of Subchronlc Toxldty Studies on Monochlorobenzene . 7-16
7-5 Mutagen1c1ty Testing of Monochlorobenzene . 7-25
7-6 Nonneoplastlc Lesions 1n F344 Rats Given Chlorobenzene by
Gavage for 2 Years 7-28
7-7 Statistical Comparisons of Liver Tumors 1n Male Rats
Treated with Chlorobenzene and Vehicle Controls 7-29
8-1 Tissue Concentrations of 1,4-01chlorobenzene 1n Adult
Female CFY Rats 8-5
8-2 Chromosomal Alterations 1n Persons Accidentally Exposed
to l,2-D1chlorobenzene 8-12
8-3 Case Reports Involving Dlchlorobenzenes (DCB) 8-13
8-4 Acute Toxldty of 1,2-D1chlorobenzene 8-19
8-5 Acute Toxldty of 1,4-D1chlorobenzene 8-20
8-6 Subchronlc Toxldty of 1,2-01chlorobenzene 8-23
8-7 Subchronlc Toxldty of 1,4-D1chlorobenzene 8-25
8-8 NTP Bloassay of 1,2-D1chlorobenzene Analysis of
Primary Tumors 1n Male Rats: Adrenal Pheochromocytomas. . . . 8-36
9-1 Distribution of "C-Labeled 1,2,4-Tr1chlorobenzene 1n Rat
Tissues after Oral Dosing with 181.5 mg/kg/day for 7 Days . . 9-3
9-2 Summary of Subchronlc and Chronic Toxldty Studies
on Tdchlorobenzenes 9-15
XV
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No. Title Page
10-1 Percentage of 1,2,4,5-Tetrachlorobenzene Steady-State
Reached at Specific Times 1n Fat and Plasma of Dogs 10-4
10-2 Time Required to Reach Various Percentages of 1,2,4,5-
Tetrachlorobenzene Steady-State 1n Fat and Plasma of Dogs . . 10-5
10-3 Unchanged Tetrachlorobenzene 1n Rabbit Tissues 6 Days
After Oral Dosing 10-6
10-4 Urinary Metabolites of Tetrachlorobenzene Isomers 1n
Rabbits 6 Days After Oral Dosing 10-9
10-5 Summary of Excretion of the IsomeMc Tetrachlorobenzenes
as Metabolites or as Unchanged Compound 1n Rabbits Dosed
Orally 10-11
10-6 Excretion of Unchanged Tetrachlorobenzenes 1n the Expired
A1r of Rabbits After Oral Dosing 10-12
10-7 Frequency of Chromat1d-type Chromosome Aberrations 1n
Peripheral Lymphocytes 10-16
10-8 Frequency of Labile Chramosome-type Aberrations 10-17
10-9 Frequency of Stable Chromosome-type Aberrations . . 10-18
10-10 Summary of Toxldty Studies on Tetrachlorobenzenes 10-19
11-1 Distribution of Pentachlorobenzene Residues 1n the
Tissues of Maternal Rats after Oral Administration 11-3
11-2 Distribution of Pentachlorobenzene Residues 1n the
Tissues of Fetal Rats after Oral Administration to Dams . . . 11-4
11-3 Distribution of Pentachlorobenzene and/or Metabolites on
the 40th Day 1n the Rhesus Monkey Following a Single Oral
Dose of 0.5 mg/kg Body Weight . 11-6
11-4 Distribution of Pentachlorobenzene 1n Chinchilla Doe
Rabbits Expressed as a Percentage of Administered Dose. . . . 11-8
11-5 Percentage of Pentachlorobenzene and Its Metabolites
Identified 1n Urine, Feces and Various Organs of Rhesus
Monkeys Dosed 0.5 mg/kg Body Weight Pentachlorobenzene. . . . 11-9
11-6 Cumulative Urinary and Fecal Excretion of Pentachlorobenzene
and Metabolites During 40 Days Following a Single Oral Dose
of 0.5 mg/kg 1n Male and Female Rhesus Monkeys 11-12
11-7 Acute Oral Toxldty of Pentachlorobenzene 11-15
XVI
-------
No. Title Rage
11-8 Summary of Subchronlc, Reproductive and Teratogenlc
Toxldty Studies on Pentachlorobenzene 11-17
11-9 Reproductive Effects 1n Litters of Female Rats Fed Diets
Containing Pentachlorobenzene ... 11-21
11-10 Toxic Effects of Pentachlorobenzene on Reproduction 1n
Rats Dosed on Each of Gestation Days 6-15 11-23
11-11 Skeletal and Soft-Tissue Abnormalities Observed 1n Rat
Litters of Dams Treated with Pentachlorobenzene on Each
of Gestation Days 6-15. ...... 11-24
11-12 Fetal Wlstar Rat Residues of Pentachlorobenzene 11-25
12-1 Storage and Excretion of 14C-HCB Administered Orally
1n Arachls 011 1n Rats 12-4
12-2 Tissue Concentration (ppm) of 14C-Hexachlorobenzene
and Its Metabolites 1n Sprague-Dawley Rats 12-6
12-3 Tissue Levels of HCB (ppm) 1n Adult Female Rhesus Monkeys . . 12-7
12-4 HCB Concentrations 1n Tissues of Male Beagles Receiving
Single Intravenous Doses of 1 mg/kg bw 1n Olive 011 12-9
12-5 Mean (+SE) Hexachlorobenzene Radioactivity (dpm/g) of
Selected European Ferret Tissues 12-14
12-6 Mean (+SE) HCB Radioactivity (dpm x TO3) of European
Ferret Kits 12-15
12-7 Concentrations of HCB and Us Metabolites (mg/kg) 1n the
Liver and Kidneys of Male and Female Rats 12-19
12-8 Hexachlorobenzene and Its Major Metabolites 1n the Excreta
of Different Animal Species 12-21
12-9 Results of Blood and Urine Analysis 1n Men Employed 1n a
Chlorinated Solvents Plant, 1974-1977 12-31
12-10 HCB Plasma Levels 1n Exposed Individuals and Controls .... 12-33
12-11 Clinical Signs and Symptoms 1n Humans 25 Years After
Exposure to Low Levels 1n HCB 1n Turkey, 1955-1959 12-36
12-12 Porphyrln Levels 1n Patients and Controls 12-38
12-13 Laboratory Test Results of Turkish Patients 12-39
12-14 Summary of Toxldty Studies on Hexachlorobenzene 12-43
XVI I
-------
No. TUIe Page
12-15 Porphyrln Content and Uroporphyrlnogen Decarboxylase
Activity 1n the Liver Cytosol of Female Rats Pretreated
with 100 mg/kg HCB Every Other Day for 6 Weeks 12-53
12-16 Tumor Incidence 1n Hamsters Given HCB 1n the Diet 12-62
12-17 HCB Levels 1n Tissues of Male Rats Following Administration
of 8 mg/kg 1n Sunflower 011 for 19 Days 12-64
12-18 HCB Levels 1n Tissues of Male Rats Following Administration
of "C-HCB 1n Arachls 011 12-65
12-19 Effect of HCB on Hamsters: Liver Tumors and Other Liver
Lesions 12-69
12-20 Liver Tumor Incidence 1n Mice Fed HCB 12-71
12-21 Tumor Data on Mice Fed HCB 12-72
12-22 Body Weights of Female Agus Rats Fed Hexachlorobenzene
for 90 Weeks 12-76
12-23 Growth Rates for Female Agus Rats on a Diet Containing
100 ppm HCB 12-78
12-24 Dosage Levels 1n the Chronic Feeding Study of
Hexachlorobenzene 1n Sprague-Dawley Rats 12-81
12-25 Liver and Kidney Tumors 1n Sprague-Dawley Rats Given
Hexachlorobenzene 1n the Diet for up to 2 Years 12-82
12-26 Adrenal Tumors 1n Sprague-Dawley Rats Given
Hexachlorobenzene 1n the Diet for up to 2 Years 12-84
12-27 Exposure Levels 1n the Chronic Feeding, 2-Generat1on
Study of Hexachlorobenzene In Sprague-Dawley Rats 12-86
12-28 Tumors 1n Organs that Showed Statistical Differences
from Control 1n F] Sprague-Dawley Rats Treated with
Hexachlorobenzene 12-88
12-29 Parathyroid and Adrenal Pheochromocytomas 1n Sprague-
Dawley Rats Maintained on Synthetic Diets of Varying
Vitamin A Content and With or Without Hexachlorobenzene . . . 12-89
12-30 Qualitative Comparison of Tumor Development 1n Rats
Following Hexachlorobenzene Administration 1n Different
Studies 12-92
12-31 Tumor Incidences 1n Male and Female Hamsters Given
Hexachlorobenzene 1n Diet 12-107
XVI I I
-------
No. Title
12-32 Incidence of Liver Cell Tumors 1n Male and Female
Swiss Mice Given Hexachlorobenzene Diet 12-108
12-33 Liver and Kidney Tumor Incidence Rates 1n Male and
Female Sprague-Dawley Rats Given Hexachlorobenzene 1n Diet. . 12-109
12-34 Incidence Rate of Adrenal Pheochromocytoma 1n Female
Sprague-Dawley Rats (F^ generation) 1n a 2-Generatlon
Feeding Study 12-110
12-35 The Carcinogenic Potency of Hexachlorobenzene, Calculated
on the Basis of 14 Data Sets, Using the Linearized
Multistage Model 12-113
12-36 Upper-Bound (Point) Estimation of Risk, Based on
Hepatocellular Carcinoma 1n Female Rats 12-115
12-37 Relative Carcinogenic Potencies Among 54 Chemicals
Evaluated by the Carcinogen Assessment Group as
Suspect Human Carcinogens 12-119
12-38 Significantly Increased Incidence of Tumors 1n
Animals Given Hexachlorobenzene 1n Diet 12-124
12-39 Analysis of the Excreta from Rats Administered Hexa-
chlorobenzene After an Initial Treatment with Dlethyl-
stllboestrol 12-132
13-1 Summary of Subchronlc Toxldty Studies on Monochlorobenzene . 13-6
13-2 Subchronlc Toxldty of 1,2-D1chlorobenzene 13-9
13-3 Subchronlc Toxldty of 1,4-D1chlorobenzene 13-11
13-4 Summary of Subchronlc and Chronic Toxldty Studies on
Trlchlorobenzenes 13-13
13-5 Summary of Toxldty Studies on Tetrachlorobenzenes 13-15
13-6 Summary of Subchronlc, Reproductive and Teratogenlc
Toxldty Studies on Pentachlorobenzene 13-16
13-7 Summary of Toxldty Studies on Hexachlorobenzene 13-17
13-8 Comparison of Toxic Effects of Chlorinated Benzene
Isomers 1n Rats 13-22
13-9 Comparison of Toxic Effects of Chlorinated Benzene
Isomers 1n Mice 13-24
13-10 Comparison of Toxic Effects of Chlorinated Benzene
Isomers 1n Rabbits 13-26
XI X
-------
No. Title page
13-11 Comparison of Toxic Effects of Chlorinated Benzene
Isomers 1n Dogs 13-28
13-12 Comparison of Toxic Effects of Chlorinated Benzene
Isomers 1n Monkeys 13-30
13-13 Toxldty Data for Threshold Estimates 13-32
13-14 Summary of Tumors Induced 1n Rodents by HCB 13-37
13-15 Comparison of Chemical and Physical Properties of
Chlorinated Benzenes 13-41
13-16 Comparison of Chlorinated Benzenes BCF and Water
Concentrations 13-42
13-17 Estimated Yearly Exposure to Several Chlorinated
Benzenes Via Inhalation 13-44
13-18 Occupational Standards for Monochlorobenzene 13-46
13-19 Occupational Standards for l,2-D1chlorobenzene 13-48
13-20 Occupational Standards for 1,4-D1chlorobenzene 13-49
13-21 The Chlorinated Benzenes as Constituents of
Hazardous Wastes from Specific Sources 13-53
13-22 Ambient Water Quality Criteria for Chlorinated
Benzenes—Aquatic Life 13-56
13-23 Ambient Water Quality Criteria for the Chlorinated
Benzenes for the Protection of Human Health 13-57
13-24 Maximum Imm1ss1on Concentration Standards for
Monochlorobenzene . 13-59
XX
-------
LIST OF FIGURES
No. Title Page
3-1 Chemical Structure of the Chlorinated Benzenes 3-2
7-1 Metabolism of Monochlorobenzene 7-7
9-1 Metabolic Pathways for TMchlorobenzene (TCB) Isomers
Through Arene Oxide Intermediates 1n Rabbits 9-7
12-1 Histogram Representing the Frequency Distribution of
the Potency Indices of 54 Suspect Carcinogens Evaluated
by the Carcinogen Assessment Group 12-118
XXI
-------
11. PENTACHLOROBENZENE
The annual production of pentachlorobenzene 1n the United States was
estimated to be 1-10 million pounds 1n 1977 (U.S. EPA, 1981a). Recent
Information Indicates that the production and Import of pentachlorobenzene
Into the U.S. 1s zero (U.S. EPA, 1983). The compound has been used as a
pesticide, a chemical Intermediate (Clement Associates, 1979; Ware and West,
1977) and as a flame retardant (Kw1atkowsk1 et al., 1976). Pentachloroben-
zene has been detected In surface waters (Barkley et al., 1980; Oliver and
Nlchol, 1982; Elder et al., 1981), drinking water contaminated by a toxic
waste site (Barkley et al., 1981), aquatic sediments (Elder et al., 1981),
fish and shellfish (Oliver and Nlchol, 1982; Ten Berge and Hlllebrand, 1974)
and In some edibles (U.S. EPA, 1980a).
11.1. PHARMACOKINETICS
11.1.1. Absorption. Pentachlorobenzene has UpophllU characteristics and
1s therefore likely to be capable of crossing biological membranes. Several
studies were available on the absorption of pentachlorobenzene after oral
administration. One study discussed absorption after dermal application;
however, no studies were available on absorption via the Inhalation route.
No studies were encountered on the distribution of pentachlorobenzene after
Inhalation or dermal exposure.
Parke and Williams (1960) studied the absorption and metabolic fate of
pentachlorobenzene 1n rabbits. Three to four days after a 0.5 g/kg dose of
pentachlorobenzene suspended 1n an aqueous solution was administered by
gavage, 5% was recovered 1n the feces and 45% was found 1n the gut con-
tents. Biliary excretion was not measured; therefore, some of the penta-
chlorobenzene found 1n the gut and feces may have resulted from a portion of
the dose that was absorbed being excreted unchanged 1n the bile. Rozman et
1834A 11-1 03/29/84
-------
al. (1979) found that absorption 1n two male and two female rhesus monkeys
was very efficient. Four days following a single dose of 0.5 mg/kg penta-
chlorobenzene by gavage, at least 95X was reported as being absorbed. Blood
and tissue levels of pentachlorobenzene and/or Us metabolites were found to
be similar to those measured for hexachlorobenzene, Indicating the Involve-
ment of the lymphatic system 1n the absorption process (latropoulos et al.,
1975). Other studies concerning the toxldty and metabolism of pentachloro-
benzene (Under et al., 1980; Engst et al., 1976; VUleneuve and Khera,
1975) also demonstrated that absorption occurs through the gastrointestinal
tract, but did not provide quantitative data.
In the only available study Involving dermal absorption of pentachloro-
benzene, Under et al. (1980) applied a single dose of 2500 mg/kg penta-
chlorobenzene dissolved 1n xylene to the shaved backs and shoulder areas of
two rats. No clinical signs of toxldty were observed In males or females,
suggesting that percutaneous absorption of pentachlorobenzene was poor.
11.1.2. Distribution. VUleneuve and Khera (1975) studied the distribu-
tion of pentachlorobenzene 1n dams and fetuses after dally administration by
gavage of pentachlorobenzene prepared 1n corn oil at levels of 40, 100 and
200 mg/kg to pregnant rats on days 6-15 of gestation. On day 22, the dams
were killed, fetuses removed and tissues analyzed by gas-Hqu1d chromato-
graphy for organohalogen residues. Recovery of pentachlorobenzene was >80%
for all tissues. In the tissues of the maternal animals, fat had the great-
est accumulation of pentachlorobenzene, followed by the liver, brain, heart,
kidneys and spleen. In the fetuses, the levels detected 1n the brain were
equal to those measured 1n the whole fetus, while the levels 1n the liver
were double the whole fetus concentration. Tables 11-1 and 11-2 show these
distribution data. Both the maternal tissues and the whole fetuses appeared
to accumulate pentachlorobenzene 1n a dose-related manner.
1834A 11-2 03/29/84
-------
TABLE 11-1
Distribution of Pentachlorobenzene Residues 1n the Tissues
of Maternal Rats after Oral Administration3
Dose Level
(mg/kg)
Residue
Fat Liver
Concentration
Brain
(mq/kg 1n wet
Heart
tissue)
Kidney
Spleen
50 470+106 13.9+5.1 6.9+1.2 6.2+1.0 6.0+1.1 4.5+J.l
100 824+116 18.1+2.0 12.0+1.7 12.6+2.0 10.6+1.5 8.3+1.3
200 3350+331 91.1+6.6 62.5±10.2 57.5+9.6 43.5+2.6 46.2+8.1
aSource: Vllleneuve and Khera, 1975
bRepresents the mean of five animals + standard error of the mean
1834A 11-3 03/29/84
-------
TABLE 11-2
Distribution of Pentachlorobenzene Residues 1n the Tissues
of Fetal Rats after Oral Administration to Dams3
Whole Fetusb
Dose Level
(mg/kg)
50
100
200
(mg/kg)
2.44±0.38
5. 27+0. 60
16.9 ±2.8
(total yg)
9.6511.3
21.2 ±2.1
55.1 ±6.7
L1verc
(mg/kg)
4.37±0.69
10.4 ±1.31
40.4 ±6.02
Bra1nc
(mg/kg)
3.08+0.55
5.3U0.60
20.5 ±2.64
aSource: Vllleneuve and Khera, 1975
^Represents the mean of two fetuses each from 15 Utters ± standard error
of the mean.
Represents the mean of five fetuses each from a different Utter ± stan-
dard error of the mean.
I834A 11-4 03/29/84
-------
Under et al. (1980) also reported that pentachlorobenzene accumulated
in the adipose tissue. Based on food consumption data provided by the
authors, groups of 10 male rats were fed 6-16 or 50-134 mg/kg/day (125 or
1QQO ppm) for 100 days, and similar groups of females were fed 6-16, 16-31,
27-63 or 55-134 mg/kg/day (125, 250, 500 or 1000 ppm) for 180 days. The
results Indicated that pentachlorobenzene accumulated 1n adipose tissue
-1.5-2.2 times the dietary concentration, and the accumulation was dose-
dependent. Residues 1n males and females were similar, but could not be
compared directly because of the longer exposure period of the females and
the complicating factors of pregnancy and lactation. Suckling pups whose
mothers were fed >250 ppm pentachlorobenzene developed tremors, and at 1000
ppm, most died before weaning. Though no clinical signs of tremors were
observed in the parents, the authors stated that this result was presumptive
evidence for excretion of a toxic agent via the milk. Because pentachloro-
benzene accumulates in the fetus (Villeneuve and Khera, 1975), prenatal
exposure of the pups may also have contributed to the observed effects.
Rozman et al. (1979) studied the distribution of pentachlorobenzene and
its metabolites 1n four rhesus monkeys. Tissues of monkeys given a single
dose of 14C-labeled pentachlorobenzene (0.5 mg/kg) by gavage were analyzed
after 40 days. Quantitative determination of pentachlorobenzene and Us
metabolites was performed by gas chromatography. The highest concentrations
were found In the fat and bone marrow, followed by the thymus, lymph nodes
and adrenal cortex. Table 11-3 summarizes the distribution data for the 20
tissues examined.
Parke and Williams (1960) studied the distribution of pentachlorobenzene
In rabbits and found that the compound was readily Isolated from the feces
and gut contents 3-4 days following administration by gavage of 0.5 g/kg.
1834A 11-5 03/02/84
-------
TABLE 11-3
Distribution of Pentachlorobenzene and/or Metabolites on the
40th Day In the Rhesus Monkey Following a Single Oral Dose
of 0.5 mg/kg Body We1ghta
Organ
Fatb
Bone marrow
Lymph nodesb
Thymus
Adrenal cortex
Adrenal medulla
Skin
Kidneys
Liver
Lungs
Spleen
Heart
B1le
Stomach
Duodenum
Cecum
Large Intestine
Small Intestine
Brain
Cerebellum
Male
(mg/kg)
1.86
1.10
0.35
0.50
0.31
0.18
0.26
0.09
0.19
0.06
0.04
0.07
0.09
0.06
0.11
0.24
0.31
0.17
0.05
0.05
Female
(mg/kg)
2.68
2.35
0.79
0.61
0.56
0.07
0.26
0.10
0.17
0.06
0.04
0.12
0.09
0.06
0.06
0.18
0.33
0.07
0.06
0.06
aSource: Rozman et a!., 1979
bAverage value from five different parts of the body
1834A
11-6
03/02/84
-------
Subcutaneous Injections of 0.5 g/kg (10% w/v solutions 1n arachls oil)
resulted 1n concentrations of 47% 1n the pelt (mostly at the site of Injec-
tion), 22% 1n the fat, a total of 2% 1n the gut and feces, and 10% 1n the
rest of the body. Table 11-4 summarizes the distribution data for penta-
chlorobenzene for this study.
11.1.3. Metabolism. The metabolism of pentachlorobenzene has been studied
1n male Wlstar rats by Engst et al. (1976) following administration by
gavage of 8 mg/kg pentachlorobenzene dissolved 1n 1 ma. of filtered sun-
flower oil. The major metabolites detected 1n the urine were Identified as
2,3,4,5-tetrachlorophenol and pentachlorophenol. Pentachlorobenzene,
2,3,4,6-tetrachlorophenol and/or 2,3,5,6-tetrachlorophenol were present 1n
the free form. Trlchlorophenol (Isomer not specified), 2,4,6-tMchloro-
phenol and 1,2,3,4-tetrachlorobenzene were present 1n small concentrations.
Quantities of the metabolites obtained were not reported for this study.
Koss and Koransky (1977) reported pentachlorophenol, 2,3,4,5-tetra-
chlorophenol, tetrachlorohydroqulonone and a hydroxylated chlorothlo com-
pound as metabolites of pentachlorobenzene 1n the urine and feces of three
female rats collected for 4 days after administering a single 1ntraper1to-
neal dose of 403 pM/kg (sic). Pentachlorophenol and other hydrophlUc
metabolites accounted for 9% of the eliminated dose.
Rozman et al. (1979) measured and Identified the metabolites of penta-
chlorobenzene 1n the rhesus monkey. Table 11-5 summarizes the metabolic
breakdown during 40 days following a single oral dose by gavage of 0.5 mg/kg
14C-labeled pentachlorobenzene. The major metabolites Identified 1n the
urine were pentachlorophenol, 2,3,4,5-tetrachlorophenol and 2,3,5,6-tetra-
chlorophenol. No significant differences were observed 1n the metabolism
patterns of male and female monkeys.
1834A 11-7 03/29/84
-------
as
•^
3>
TABLE 11-4
Distribution of Pentachlorobenzene 1n Chinchilla Doe Rabbits
Expressed as a Percentage of Administered Dose3
1
CO
Dose/Route
(g/kg)
0.5 oral
0.5 oral
0.5 s.c.
Time
After
Dosing
(days)
3
4
10
Urine
Tr1- or Penta-
chlorophenol
0.2
0.2
0.7
Expired Air
Other
Phenols
1
1
1
Feces
5.0
5.0
1.5
Gut
Contents
45.0
31.0
0.5
Pelt
1.0
5.0
47. Ob
Depot
Fat
15.0
9.0
22. 0&
Rest of
Body
6.0
5.5
10.0
Unchanged
0
0
0
Other Chloro-
hydrocarbons
9.0
21.0
<2.0
Total
Accounted
%
82
78
85
^Source: Parke and H111 lams, 1960
DLocated mainly at site of Injection
s.c. = subcutaneous
o
CO
no
10
co
-------
CO
00
TABLE 11-5
Percentage of Pentachlorobenzene and Its Metabolites Identified In Urine, Feces and
Various Organs of Rhesus Monkeys Dosed 0.5 mg/kg Body Weight Pentachlorobenzene*
Liver
Bile
Feces
Blood
Kidney
Urine
Pentachlorobenzene
99. OX
nonpolar compound! s)
99. OX
45. 8X
51 3<
ND
1 ,2, 3,4-Tetrachlorobenzene
l.OX
nonpolar compound(s)
l.OX
ND
ND
ND
Pentachlorophenol
ND
ND
ND
54. 2X
/
j -_-__-
58. IX
2,3,4,5-Tetrachlorophenol 2,3,
ND
ND
ND
ND
32. 2X
,5,6-Tetrachlorophenol
ND
ND
ND
ND
\
9.7X
*Source: Rozman et al., 1979
ND = Not detected
o
CO
CD
-------
Similar results were obtained by KohH et al. (1976) 1n male rabbits.
Following Intraperltoneal Injection of 300 mg pentachlorobenzene dissolved
In 10-15 ma, vegetable oil, urinary metabolites were Identified as 2,3,4,5-
tetrachlorophenol and pentachlorophenol. Both were detected at yields of 1%
during the 10 days following administration of the dose. Parke and Williams
(1959) reported that
-------
Kohll et al., 1976; Parke and Williams, 1960). Rozman et al. (1979) demon-
strated that the half-life of pentachlorobenzene 1n the rhesus monkey was
2-3 months, and after 40 days pentachlorophenol accounted for 58.1% of the
metabolites Identified 1n the urine.
11.1.4. Excretion. The excretion of pentachlorobenzene and Us metabo-
lites was described 1n rhesus monkeys following administration by gavage of
a single oral dose of 0.5 mg/kg (Rozman et al., 1979). Approximately 12% of
the administered dose was excreted 1n the urine after 40 days (see Table
11-5). After the same period, -24% of the dose was excreted via the feces,
of which 99% was unmetabollzed. Table 11-6 displays the cumulative urinary
and fecal excretion of pentachlorobenzene and Its metabolites. This study
Indicated that the metabolites of pentachlorobenzene were excreted primarily
via the urine, while the unabsorbed or unmetabollzed compound was excreted
via the feces. These results also Indicated that pentachlorobenzene was
eliminated very slowly, with an estimated excretion half-life 1n primates of
2-3 months.
Koss and Koransky (1977) identified 3% pentachlorobenzene In Us un-
changed form, pentachlorophenol, 2,3,4,5-tetrachlorophenol and a hydroxylat-
ed chlorothio compound In the feces of rats 4 days after intraperitoneal
administration of 403 pM/kg (sic) pentachlorobenzene. Parke and Williams
(1960) also Isolated 5% pentachlorobenzene after 4 days from the feces of
rabbits given 0.5 g/kg pentachlorobenzene orally.
Under et al. (1980) fed pentachlorobenzene (250-1000 ppm) to female
Sherman rats with suckling pups and observed that the pups developed tremors
and most died before weaning in the 1000 ppm group. This work provides
presumptive evidence for excretion of pentachlorobenzene via the milk.
1834A 11-11 03/29/84
-------
TABLE 11-6
Cumulative Urinary and Fecal Excretion of Pentachlorobenzene and
Metabolites During 40 Days Following a Single Oral Dose of
0.5 mg/kg 1n Male and Female Rhesus Monkeys3*^
4
Males
urine 1.9
feces 6.3
Females
urine 2.4
feces 4.4
Days After
10 20
4.8 8.6
11.5 19.3
4.3 7.8
8.3 16.4
Exposure
30
11.3
23.6
10.0
19.8
%
40 Total
Recovered
13.2 40,2
27.0
]1-4 33.2
21.8
aSource: Rozman et al., 1979
Expressed 1n percent of the total administered dose
1834A
11-12
03/29/84
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11.1.5. Summary. Although studies of the absorption of pentachlorobenzene
Indicated that absorption does occur through the gastrointestinal tract, the
extent of absorption has not been determined. A study In rabbits Indicated
that up to 50X of a dose was absorbed within 3-4 days. Oral administration
to monkeys Indicated 95X absorption within 4 days. Absorption resulting
from Inhalation has not been studied, and absorption from dermal exposure
was found to be rather poor In rats. Once absorbed, pentachlorobenzene 1s
widely distributed to many tissues, with the highest levels appearing 1n
fat, liver and bone marrow. A study In rats demonstrated that transport
across placental membranes occurred readily and that accumulation of penta-
chlorobenzene In the fetus 1s highest 1n the liver. No studies were encoun-
tered that described the distribution of pentachlorobenzene after Inhalation
or dermal exposure.
The metabolism of pentachlorobenzene 1s not fully understood, but some
studies suggested that metabolic activity other than the hepatic cytochrome
P-450, xenoblotlc metabolizing system may be Involved. Metabolism appeared
to be primarily via oxidation to two major metabolites, pentachlorophenol
and 2,3,4,5-tetrachlorophenol, which were excreted In the urine. Metabolism
and excretion occurred at a slow rate; an estimated elimination half-life
for a single dose In primates was 2-3 months.
11.2. EFFECTS ON HUMANS
No epldemlologlc studies or case studies of effects 1n humans resulting
from exposure to pentachlorobenzene were available for review.
11.3. MAMMALIAN TOXICOLOGY
11.3.1. Acute ToxIcHy. Llnder et al. (1980) Investigated the acute and
subchronlc toxiclty of 99.1% pure pentachlorobenzene In adult and weanling
Sherman strain rats and adult Swiss-Webster mice. Weanling rats (27-35 days
1834A 11-13 03/02/84
-------
of age; 10 animals/dosage level) and adult animals (90-120 days of age; 10
animals/dosage level) were administered by gavage a single dose of 5.0-15.0
mil/kg pentachlorobenzene dissolved In peanut oil. The oral LD values
ranged from 1080-1125 mg/kg for adult rats, and 1175-1370 mg/kg for adult
mice; for weanling rats the LD was reported as 940 mg/kg (Table 11-7).
The characteristic toxic signs observed Included a decrease 1n activity,
hypersensltlvlty to touch, and tremors. The tremors started 1n mice -24
hours after dosing and -48 hours after dosing 1n rats. Death usually
occurred In rats 5-12 days after dosing; In mice the survival time was less,
with death usually occurring 2-4 days after the lethal dose was adminis-
tered. The authors reported many cases of rats with reddish stains around
the eyes, nose and mouth; no explanation of this phenomenon was given.
AMyoshl et al. (1975) Investigated the effects of various chlorinated
benzenes, Including pentachlorobenzene, on the mlcrosomal drug metabolizing
enzymes, 6-am1nolevul1n1c add synthetase, mlcrosomal proteins and cyto-
chrome P-450 content. Groups of 2-6 female Wlstar rats were orally adminis-
tered 250 mg/kg pentachlorobenzene suspended 1n a 2% tragacanth gum solu-
tion, once a day for 3 days. The compound Increased the liver content of
cytochrome P-450 and Increased the activities of aniline hydroxylase and
amlnopyrlne demethylase. Significant Increases were also observed for
mlcrosomal protein and 6-am1nolevul1n1c add synthetase. Glycogen content
decreased markedly, and trlglycerlde content Increased 1n pentachloroben-
zene-treated rats.
In the only available study Involving acute dermal toxldty of penta-
chlorobenzene, Under et al. (1980) applied a single dose of 2500 mg/kg
pentachlorobenzene dissolved 1n xylene to the shaved backs and shoulder
areas of two rats. No clinical signs of toxldty were observed In either
male or female adult rats.
1834A 11-14 03/02/84
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TABLE 11-7
Acute Oral Toxlclty of Pentachlorobenzene*
Species/
Sex
Rat/M
Rat/F
Rat/F
Mouse/M
Mouse/F
Age
adult
adult
weanling
adult
adult
LD50
(mg/kg)
1125
1080
940
1175
1370
95% Confidence
Limits
(mg/kg}
1015-1247
952-1226
864-1023
1035-1334
1263-1487
Dosage
Range
Tested
(mg/kg)
750-1350
750-1500
600-1200
750-1500
1050-1500
Dose
Volume
(ml/kg)
7.5
7.5
5.0
15.0
15.0
*Source: Llnder et al., 1980
Weanling animals were 27-35 days old. Adult animals were 90-120 days old.
Ten animals per each dosage group were given pentachlorobenzene dissolved 1n
peanut oil.
1834A
11-15
03/02/84
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11.3.2. Subchronlc ToxUHy. No studies of toxUHy resulting from
subchronlc Inhalatory exposure to pentachlorobenzene were located 1n the
available literature. A summary of subchronlc, reproductive and teratogenlc
toxldty studies on pentachlorobenzene can be found 1n Table 11-8.
Under et al. (1980) studied the subchronlc toxldty of pentachloroben-
zene 1n rats as part of an Investigation of the compound's toxic effects on
reproduction. Groups of 10 female weanling rats were fed diets containing
0, 125, 250, 500 and 1000 ppm of pentachlorobenzene for -180 days; while
groups of 10 male rats received 0, 125 and 1000 ppm for 100 days. Based on
food consumption data provided by the authors, 1t was estimated that the
female groups consumed an average of 11, 23, 46 and 99 mg/kg/day, respec-
tively (actual reported ranges of 7-16, 16-31, 27-63 and 55-134 mg/kg/day).
The male groups consumed -11 and 97 mg/kg/day, respectively (reported ranges
of 7-16 and 50-134 mg/kg/day). None of the animals died or exhibited clini-
cal signs of toxldty throughout the study. Food consumption and body
weight gain for the dosed groups were similar to the control groups. In
hematologlc parameters, erythrocyte count and hematocrlt were slightly lower
than the control group (p<0.05) for the 1000 ppm males, and hemoglobin was
reduced and leukocyte count Increased 1n both 1000 ppm groups (p<0.05).
Examination of the liver and viscera under ultraviolet light did not
reveal the presence of porphyrlns 1n males or females. Only tissues of the
female rats were analyzed quantitatively for porphyrlns. Total liver
porphyrlns were slightly higher In female rats fed 1000 ppm compared with
the control group (0.79 pg/g compared with 0.64 pg/g), but the differ-
ence was not judged to be a porphyrogenlc response and was of doubtful
consequence.
1834A 11-16 03/29/84
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03
00
TABLE 11-8
Summary of Subchronlc, Reproductive and Teratogenlc ToxIcUy Studies on Pentachlorobenzene
Species
Route
Dose
Duration
Effects
Reference
Rat (female) oral 125, 250, 500
(diet) or 1000 mg/kg
1n diet
Rat (male) oral 125 or 1000
(diet) mg/kg 1n diet
Rat oral 125, 250, 500
(offspring) (diet) or 1000 mg/kg
In mothers diet
Mice oral 50 or 100
mg/kg/gavage
Rat oral 50. 100 or 200
mg/kg/gavage
180 days
100 days
gestation and
during suckling
days 6-15 of
gestation
days 6-15 of
gestation
Changes 1n hematologlc parameters 1n high-
dose group; Increase In liver weights,
hepatic hypertrophy and vacuollzatlon 1n
500 and 1000 mg/kg groups; Increased kid-
ney weight 1n high-dose group
High-dose group Induced changes 1n hemato-
loglc parameters; hepatic and renal
histology and Increase 1n liver, kidney
and adrenal weights
Offspring treated with >250 mg/kg/dlet were
adversely affected (reduced survival, body
weights and Increased liver weights, hepato-
cellular enlargement)
Increase In liver weights of dams; no
adverse effects on total development or
survival
No observed toxldty 1n adult rats; In-
creased total deaths at all doses, but not
1n dose-related manner; extra ribs 1n ex-
posed fetuses and sternal defects In 200
mg/kg group
Under et al.. 1980
Under et al., 1980
Under et al., 1980
Courtney et al., 1979
Khera and Vllleneuve,
1975
o
CO
en
•*v
c»
-------
Tissues of 21-day-old weanlings appeared normal although relative
weights (organ/body weight ratio) of the livers were Increased 1n pups of
mothers fed >250 ppm for 180 days. The obvious change was hepatocellular
enlargement In all pups from the groups fed 500 and 1000 ppm.
At necropsy of the adult rats, no pathological changes were observed 1n
tissues of males fed pentachlorobenzene for 100 days or females fed penta-
chlorobenzene for 180 days. Weights of livers relative to body weight
Increased 35-45X 1n the animals fed 500 or 1000 ppm. Relative weights of
the kidneys of both sexes and the adrenals of males Increased In the 1000
ppm groups. Microscopically, hepatic cell enlargement (hypertrophy) and
vacuollzatlon were observed 1n the female rats of the 500 and 1000 ppm
groups. Similar changes were apparent 1n the males fed 1000 ppm. In high-
dose groups, the kidneys of males showed hyaline droplet formation, atrophlc
tubules and lymphocytlc Infiltration. Results of this study Indicated that
the toxlclty of orally administered pentachlorobenzene was directed toward
the liver and kidneys.
The ability of pentachlorobenzene to Induce porphyrla In Wlstar rats has
been Investigated by Goerz et al. (1978). Adult female rats were fed a diet
containing 0.05X (-25.0 mg/kg/day or 500 ppm) pentachlorobenzene for 60
days. This treatment Increased the hepatic cytochrome P-450 content
(1.06*0.30 and 1.20.f0.30 nMol/mg mlcrosomal protein for 10 and 60-day
exposures, respectively, for the controls compared with 2.25^1.10 and
2.06^0.65 nMol/mg mlcrosomal protein, for 10 and 60-day exposures for the
pentachlorobenzene-treated rats), but did not Increase the excretion of
porphyrlns 1n the urine.
11.3.3. Chronic Toxldty. No studies of toxldty resulting from chronic
exposure of pentachlorobenzene were located In the available literature.
1834A 11-18 03/02/84
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11.3.4. MutagenlcHy. The only Information available on the mutagenlcHy
of pentachlorobenzene was a study presented 1n abstract form on a plate
Incorporation assay for reverse mutation 1n h1st1d1ne-dependent strains of
Salmonella typhlmurlum (Lawlor et al., 1979). Five strains of Salmonella
typhlmurlum (TA98, TA100, TA1535, TA1537 and TA1538) were tested at five
unspecified concentrations of pentachlorobenzene 1n the presence and absence
of rat liver mlcrosomes Induced by Aroclor 1254. No detectable levels of
mutagenlc activity were found 1n the Salmonella tester strains (Lawlor et
al., 1979). Because these results were reported 1n an abstract, experiment-
al details were too sparse to permit a critical evaluation of this negative
result. Also, this result 1s not unexpected because the Salmonella test
system 1s generally Insensitive to chlorinated compounds.
11.3.5. Carcinogenicity. The Ambient Water Quality Criteria Document for
Chlorinated Benzenes (U.S. EPA, 1980b) cited a study by Preussman (1975)
that was reported as alluding to the carclnogenldty of pentachlorobenzene.
The German text 1s now being translated and reviewed by the Carcinogen
Assessment Group of the U.S. EPA.
11.3.6. Reproductive and Teratogenic Toxicity. The reproductive toxldty
of pentachlorobenzene was demonstrated 1n three studies. Of these studies,
Under et al. (1980) and Khera and Vllleneuve (1975) provided sufficient
data to estimate a NOEL and a LOAEL, respectively.
Llnder et al. (1980) tested 99.1% pure pentachlorobenzene for Its toxic
effects on reproduction 1n rats. No other chlorinated compounds were
detected by GC-EC analysis of the sample. Dietary concentrations of 0
(control), 125, 250, 500 and 1000 ppm (7.4-16, 16-31, 27-63 and 55-134
mg/kg/day) were fed by gavage to groups of ten 4- to 5-week-old weanling
female Sherman strain rats, while similar groups of males received diets
1834A 11-19 03/29/84
-------
containing 0 (control), 125 or 1000 ppm (6-16 or 50-134 mg/kg/day). Both
males and females were fed treated diets for 67 days before mating with
untreated males or females. Pregnant females continued to receive treated
diets until their Utters were weaned, for a total exposure of 180 days;
males were dosed for a total of 100 days before being sacrificed.
Litters sired by treated males showed no treatment-related effects.
Although clinical signs were not observed 1n the parents, Utters from
treated females (>250 ppm) were adversely affected. Pup survival and body
weight at weaning were reduced 1n the two highest dose groups, and the off-
spring of the 250, 500 and 1000 ppm groups showed statistically significant
(p<0.05) Increases 1n I1ver-to-body weight ratios. Survival decreased
dramatically from 88.6 to 28.0% during days 4-21 for pups whose mothers were
fed concentrations of 500 and 1000 ppm, respectively. Table 11-9 summarizes
the reproductive effects 1n Utters of treated females.
H1stolog1c examination of the livers of weanling rats revealed hepato-
cellular enlargement In all pups examined from the 500 and 1000 ppm groups,
and In 2 of 9 male pups from the 250 ppm group. The hepatotoxlc effects
were not seen 1n the offspring of the dams exposed to dietary concentrations
of 125 ppm. These data Indicated that pentachlorobenzene was transferred to
the offspring during gestation and/or lactation and had a toxic effect on
the pups 1n the 250, 500 and 1000 ppm groups. Therefore, this study sug-
gested a NOEL of 125 ppm 1n the diet for no toxic effects on the reproduc-
tion of rats.
In a study by Khera and Vllleneuve (1975), pregnant Wlstar rats
(17-19/group) were administered pentachlorobenzene by gavage on days 6-15 of
gestation. The doses 1n mg/kg with percentage concentrations 1n corn oil
(1n parentheses) were 50 (0.5), 100 (1.0) or 200 (2.0). Uterine and viscera
1834A 11-20 03/29/84
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oo TABLE 11-9
GO
Reproductive Effects in Utters of Female Rats Fed Diets Containing Pentachlorobenzene3
Pentachlorobenzene in Diet (ppm)
Parameter
Dosage range (mg/kg/day)
Litters born
Pups per litter (mean)
Litters weaned
Pup survival (%)
Days 0-4
Days 4-21
Pup body weight at Male
weaningb Female
Liver/body weight Male
ratio0 (g/100 g) Female
0
NA
8
10.4
8
100
100
45 (5)
45 (8)
3.9 (0.1)
4.0 (0.1)
125
6-16
6
12.0
6
98.6
91.7
44 (3)
41 (3)
3.9 (0.1)
3.9 (0.1)
250
16-31
9
11.9
9
98.1
95.4
41 (4)
40 (3)
4.3 (0.1)d
4.2 (0.1)
500
27-63
9
13.2
9
98.3
88.6
40 (4)
38 (4)
5.1 (0.1)d
5.3 (0.1)d
1000
50-134
8
10.8
4
94.2
28.0
31 (4)
37 (4)
6.5 (0.1
6.5 (0.2
>d
)d
aSource: Llnder et al., 1980
bValues are litter means in grams (+_ standard deviation)
cValues are group means (+_ standard error of the mean)
o dSignificantly different from control; p=0.05 (statistical analysis performed on liver weights only)
CO
V.
£ NA = Not applicable
CO
-------
contents were removed following sacrifice of the dams on day 22 of gesta-
tion. No overt signs of toxldty were observed 1n the adult rats; however,
the treatment Increased fetal death rate at all of the doses tested, but not
1n a dose-related manner (Table 11-10). This study demonstrated a lethal
effect of _^n utero exposure to pentachlorobenzene at doses to the dams as
low as 50 mg/kg/day, therefore Identifying a LOAEL for this study.
Khera and VUleneuve (1975) also reported that sternal defects were
observed 1n the fetuses of Wlstar rat mothers treated with 200 mg/kg/day.
In addition, all three doses Increased the Incidence of both un1- and
bilateral extra ribs (Table 11-11). The latter effect (Increase 1n extra
ribs), although not a gross malformation, occurred at an Incidence 5-9 times
greater than the controls, Indicating a potential for pentachlorobenzene to
alter fetal skeletal development. In addition, quantitative chemical
analysis of fetuses for pentachlorobenzene residues showed a dose-related
accumulation of the unchanged compound 1n the whole fetus, brain and liver
(Table 11-12) (VUleneuve and Khera, 1975). These results suggested that
the parent compound may have been responsible for the observed teratogenlc
and reproductive effects, but did not preclude metabolites as potential
causes of the observed effects.
In a study of possible reproductive and teratogenlc effects, Courtney et
al. (1977) reported that no reproductive toxldty occurred 1n Utters of
pregnant CD-I mice treated by gavage with 50 or 100 mg/kg of >97% pure
pentachlorobenzene 1n 0.1 ma corn oil on days 6-15 of gestation. There
were no teratogenlc effects observed 1n the 10 or 9 Utters whose mothers
had been treated with 50 or 100 mg/kg, respectively, when compared with the
6 control Utters. There was, however, a significant Increase (p=0.01) 1n
the liver weight and the I1ver-to-body weight ratio of the treated mice
1834A 11-22 03/29/84
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TABLE 11-10
Toxic Effects of Pentachlorobenzene on Reproduction
in Rats Dosed on Each of Gestation Days 6-15a
Pentachlorobenzene
Parameter
Number of rats pregnant at term
Live fetuses per Utter
Fetal death (%)b
Fetal mean body weight (g)
0
19
12.1
1.3
4.8
50
18
12.5
4.2
4.9
Dose (mg/kg/day)
100
19
11.5
3.1
4.8
200
17
10.7
3.2
4.4
aSource: Khera and Vllleneuve, 1975
bPercent fetal death = (no. dead plus dedduomas) x 100/total no. of Implants
1834A 11-23 03/02/84
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TABLE 11-11
Skeletal and Soft-Tissue Abnormalities Observed In Rat Utters of
Dams Treated with Pentachlorobenzene on Each of Gestation Days 6-15*
Pentachlorobenzene Dose (mg/kg/day)
Parameter 0 50 100 200
Skeletal Defects
No. of fetuses examined 127 129 122 100
Extra ribs: unilateral 2 18 10 17
bilateral 2 10 11 46
Fused ribs NA NA NA 2
Wavy ribs 52 NA NA
Sternal defects 5 4 NA 31
Exencephaly NA NA NA NA
Soft-Tissue Anomalies
No. of fetuses examined for
visceral defects 67 69 67 52
Runts 1 2 NA 2
Cleft palate NA 1 NA NA
Cardiac defects NA NA NA NA
Other Defects NA NA NA 2
*Source: Khera and Vllleneuve, 1975
NA = No abnormality observed
1834A 11-24 03/02/84
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TABLE 11-12
Fetal Wlstar Rat Residues of Pentachlorobenzene3*0
Maternal
Intubated
Dose Level
(mg/kg)
50
100
200
Whole Fetus
(ppm)
2.44 + 0.38
5.27 + 0.60
16.9 + 2.8
(Total
9.65
21.2
55.1
yg)
+ 1.3
+ 2.1
+ 6.7
L1verd
(ppm)
4.37 + 0.69
10.4 + 1.31
40.4 + 6.02
Bra1nd
(ppm)
3.08 + 0
5.31 i 0
20.5 + 2
.55
.60
.64
aSource: Adapted from Vllleneuve and Khera, 1975
DPregnant rats were exposed to pentachlorobenzene during days 6-15 of
gestation and the fetuses were removed and analyzed on day 22.
Represents the mean of two fetuses from 15 Utters +_ s.e.m.
^Represents the mean of five fetuses each from a different Utter +_ s.e.m.
1834A
11-25
03/15/84
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compared with the control mice. Pentachlorobenzene had no adverse effect on
fetal development or survival. One fetus 1n the 50 mg/kg dose group
displayed a cleft palate, but the occurrence was within the normal Incidence
for this strain of mice.
11.4. INTERACTIONS
Arlyoshl et al. (1975) and Goerz et al. (1978) demonstrated the ability
of pentachlorobenzene to Increase the activity of NADPH-cytochrome P-450
dependent enzyme systems 1n rats. Induction of the cytochrome P-450
monoxygenase-catalyzed metabolism could result In an Increase or decrease 1n
the toxlclty of the compound. Therefore, exposure to pentachlorobenzene
could result In the blotransformatlon and toxlclty of drugs and other
chemicals. However, no studies were available to support this.
11.5. SUMMARY
Pentachlorobenzene Is absorbed from the gastrointestinal tract; studies
Indicated that 50-95% of an administered dose 1s absorbed within 4 days.
One study that measured absorption through the skin suggested that penta-
chlorobenzene was poorly absorbed. No studies were available that measured
absorption through the lungs.
Distribution Is to many tissues, primarily the fat, liver and bone
marrow. Transfer across placental membranes and excretion Into the milk
probably occur.
Metabolism Is believed to be by oxidation to phenolic compounds, espe-
cially pentachlorophenol, that are excreted In the urine. Excretion appears
to occur slowly; an estimated half-life 1n primates Is 2-3 months.
No data were available on the effects of exposure to pentachlorobenzene
In humans, and no chronic or carc1nogen1c1ty studies were available for
review.
1834A 11-26 03/02/84
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Oral LDr0 values were determined for adult rats (1080-1125 mg/kg) and
mice (1175-1370 mg/kg), and for weanling rats (940 mg/kg). No clinical
signs of toxldty were observed 1n adult rats following dermal application
of 2500 mg/kg pentachlorobenzene. Also, H was demonstrated that penta-
chlorobenzene caused an Increase 1n the liver content of cytochrome P-450,
mlcrosomal drug metabolizing enzymes and mlcrosomal proteins.
A subchronlc feeding study Indicated that the primary toxic effects are
on the liver and kidneys, although slight changes 1n some hematologlc
parameters (e.g., decreased erythrocyte count, hemoglobin and hematocrlt;
Increased leukocyte count) occurred 1n the high-dose groups. H1stolog1c
examination Identified pathologic changes 1n the livers of the female rats
fed 500 and 1000 ppm for 180 days and 1n the 1000 ppm male rats treated for
100 days. These data were sufficient to Identify a subchronlc LOAEL of 500
ppm (-27-63 mg/kg/day) and a NOEL of 250 ppm (-16-31 mg/kg/day).
No mutagenlc activity was detected 1n five strains of Salmonella typhl-
muMum when tested at five unspecified concentrations of pentachlorobenzene
1n the presence and absence of rat liver mlcrosomes Induced by Aroclor 1254.
These results were reported 1n an abstract with few experimental details.
Also, a negative result for pentachlorobenzene 1s not unexpected, because
the Salmonella assay 1s generally Insensitive to chlorinated compounds.
Studies also have shown that pentachlorobenzene 1s capable of causing
reproductive and developmental effects. Female rats fed diets containing
pentachlorobenzene during mating and gestation produced Utters with reduced
pup survival and body weights at weaning, and Increased I1ver-to-body weight
ratios. No adverse effects were observed 1n the offspring of the dams
exposed to 125 ppm (6-16 mg/kg/day).
1834A 11-27 03/29/84
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Single oral doses of pentachlorobenzene given dally to pregnant rats
during gestation Increased the Incidence of fetal death at all doses tested.
Identifying a LOAEL of 50 mg/kg/day. Sternal defects and an Increase In the
Incidence of extra ribs also were observed at doses of 200 mg/kg/day and 50,
100 and 200 mg/kg/day, respectively.
In a study of possible reproductive and teratogenlc effects, doses of 50
and 100 mg/kg/day of pentachlorobenzene administered by gavage to pregnant
mice had no adverse effect on fetal development or survival.
1834A 11-28 03/02/84
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12. HEXACHLOROBENZENE
Hexachlorobenzene is not manufactured as a commercial product 1n the
United States, but an estimated 2-5 million pounds were produced each year
during the synthesis of several chlorinated chemicals (Mumma and Lawless,
1975). Hexachlorobenzene 1s also an Ingredient 1n a fungicide of which
-200,000 pounds are Imported each year (IARC, 1979). Hexachlorobenzene 1s
resistant to blodegradatlon, accumulates 1n the biological environment and
has been detected 1n ambient air, drinking and surface water, sediments,
cropland and food (see Section 4.3.). Hexachlorobenzene residues also have
been found 1n samples of human blood, fat and breast milk. The greatest
degree of human exposure 1s most likely to occur 1n the workplace and near
manufacturing and disposal sites, although the general population is likely
to be exposed through Inhalation of polluted air and the Ingestlon of
contaminated food and water.
12.1. PHARMACOKINETICS
12.1.1. Absorption. Absorption of hexachlorobenzene from the gut has been
studied 1n detail; however, no Information has been found 1n the available
literature on hexachlorobenzene absorption through the lungs or skin.
Absorption of hexachlorobenzene from the Intestinal tract appears to depend
on the solvent vehicle used during test material administration. Thus, when
hexachlorobenzene 1s administered 1n olive oil, -8054 of the dose 1s
adsorbed; when 1t 1s administered 1n an aqueous solution, 1n 1% methyl
cellulose, or 1n a crystalline form, relatively Uttle (<20%) 1s absorbed.
Intestinal absorption of hexachlorobenzene occurs primarily through lym-
phatic channels (latropoulos et al., 1975), with only a minor portion being
absorbed Into the portal circulation.
1835A 12-1 03/23/84
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IngebMgtsen et al. (1981) Investigated the absorption of [14C]hexa-
chlorobenzene (10 mg 1n peanut oil) administered to male, blle-duct-cannu-
lated Wlstar rats by gastric catheter. Four days after dosing, 24.8% of the
administered 14C had been recovered 1n the feces, Indicating that at least
75% of the administered hexachlorobenzene was absorbed,
Albro and Thomas (1974) studied the absorption of hexachlorobenzene 1n a
squalane/cotton seed oil vehicle by male rats following administration of a
single dose by stomach Intubation. The results Indicated that at doses of
12 and 30 mg/kg, -82 and 72%, respectively, were absorbed within 96 hours.
Koss and Koransky (1975) compared the absorption rates of [14C]hexa-
chlorobenzene 1n female Wlstar rats following oral administration of olive
oil solutions or suspensions 1n 6% gum arable 1n water (4, 20, 50.5, 60 and
180 mg/kg). Approximately 80% of the dose was absorbed from the olive oil
solutions; however, only 6% was absorbed from the aqueous suspension.
Similarly, Zablk and Schemmel (1980) found that, when hexachlorobenzene
(32 mg/kg/day) was administered 1n the diet, high-fat (45.3% w/w) diets
resulted 1n greater accumulation of hexachlorobenzene In the tissues and
less hexachlorobenzene excreted 1n the feces than did high-carbohydrate
diets (67.7% w/w). The female rats received 32 mg/kg body weight hexa-
chlorobenzene/day for 6, 12 or 18 days. Although this study did not Include
a control group receiving a balanced diet, the data suggest that high fat
diets Increase the absorption of hexachlorobenzene.
Sundlof et al. (1982) administered seven consecutive dally oral doses of
10 or 100 mg crystalline hexachlorobenzene/kg body weight to male laboratory
beagles. The results from the 100 mg/kg group Indicated that hexachloro-
benzene can continue to be absorbed from the Intestines for up to 1 week
following the cessation of dosing.
1835A 12-2 03/23/84
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Bleavlns et al. (1982) fed female European ferrets (Hustela putoMus
furo) a single dose of 57.6 yg hexachlorobenzene (14C-labeled) In 7.5 g
of standard mink diet (22% fat) and calculated that 98.5% of the hexachloro-
benzene dose was absorbed by the ferrets. They made this calculation based
on predicted hexachlorobenzene excretion as extrapolated from this study,
and owing to a food passage time 1n the female ferret of just over 3 hours.
12.1.2. Distribution. Following Intestinal absorption, hexachlorobenzene,
which 1s I1poph1l1c, distributes to tissues that are rich 1n I1p1d content.
The adipose tissue accumulates the greatest concentrations of hexachloro-
benzene 1n all species studied, although bone marrow and skin, which contain
large amounts of Uplds, also accumulate hexachlorobenzene. The adrenal
cortex accumulates hexachlorobenzene at concentrations approaching those of
fat. Other tissues (e.g., kidneys, lungs, heart, spleen and blood) gen-
erally contain lower amounts of hexachlorobenzene. Intravenous Injection of
hexachlorobenzene results 1n a tissue distribution similar to that following
oral administration. Hexachlorobenzene 1s transported via the placenta and
1s distributed 1n fetal tissue.
Mehendale et al. (1975) studied the disposition of ^C-hexachloro-
benzene by adult male rats following a single oral dose of 5 mg/kg.
14C-Hexachlorobenzene was mixed with arachls oil and administered by
stomach Intubation at a dose of ~5 mg/kg. The animals were sacrificed 7
days later and the tissues and organs radloassayed. Forty-three percent of
the total radioactivity administered was present 1n fat tissue 7 days after
14C-hexachlorobenzene administration. In addition, muscle and skin tis-
sues each contained -9% of the radioactivity, whereas the other 12 tissues
analyzed contained ~5X combined (Table 12-1).
1835A 12-3 03/23/84
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TABLE 12-1
Storage and Excretion of 1«C-HCB Administered Orally
1n Arachls 011 1n Rats3
Organ or Tissue
Fatb
Musclec
Sklnd
Liver
Small Intestine
Bone6
Kidneys
Large Intestine
Stomach
Blood
Lungs
Testes
Heart
Brain
Spleen
Total 1n tissues
Excretion
Feces
Urine
Gut contents
Total recovery
Percent of Total
Radioactivity
Administered
42.81 + 6.14
9.41 + 1.17
8.64 + 1.21
3.01 + 0.23
2.43 t 0.47
1.04 + 0.09
0.76 + 0.11
0.43 + 0.08
0.36 + 0.04
0.24 + 0.04
0.24 + 0.04
0.21 + 0.04
0.18 + 0.03
0.17 + 0.03
0.04 ± 0.002
70.09 + 5.48
16.02 + 2.31f
0.85 + 0.13f
2.48 ± 0.45
89.44 v 10.57
aSource: Mehendale et al., 1975
bBased on 9% body weight as fat
cBased on 50% body weight as muscle
dBased on 16% body weight as skin
eBased on 10% body weight as bone
^Cumulative total for 7 days
Adult male rats were given 5 mg/kg of hexachlorobenzene.
HCB = Hexachlorobenzene
1835A
12-4
03/23/84
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When I4C-hexachlorobenzene was suspended In 1% methyl cellulose and a
single oral dose containing 150 vg of hexachlorobenzene was administered
to Sprague-Dawley rats, the absorption of 14C-hexachlorobenzene by the
walls of the stomach and duodenum 1 hour later was relatively low: -1.0 and
0.6 ppm were found 1n the stomach and duodenum, respectively (latropoulos et
al., 1975). Increased radioactivity was found 1n the jejunum and 1leum as
well as the lymph nodes and adipose tissues 3 hours after administration
(Table 12-2). Although the radioactivity also Increased 1n the liver and
kidneys, this Increase was relatively low compared to that found In the
lymph nodes and adipose tissue. Moreover, the radioactivity 1n the liver
and kidneys decreased within a 2-day period, whereas the radioactivity 1n
the lymph nodes and fat remained relatively constant. These results Indi-
cate that the portal venous transport of hexachlorobenzene to the liver
appears to be a minor pathway, whereas the major part of the Ingested hexa-
chlorobenzene 1s absorbed by the lymphatic system 1n the duodenum and
jejuno-1leum and deposited 1n the fat, bypassing the systemic circulation
and the excretory organs.
Knauf and Hobson (1979) Investigated the tissue distribution of hexa-
chlorobenzene 1n six female rhesus monkeys following the administration of
dally doses of hexachlorobenzene [0 (one monkey), 8 (one monkey), 32 (one
monkey), 64 (one monkey), or 128 (two monkeys) mg/kg/day] 1n 1% methyl
cellulose for a period of 60 days. The highest concentrations of hexa-
chlorobenzene were located 1n tissues with high I1p1d content. Tissue
levels correlated more with body fat content than with dose, with the monkey
that had the least adipose tissue producing the highest nonfat tissue and
serum values (Table 12-3).
1835A 12-5 03/23/84
-------
OD
" TABLE 12-2
Tissue Concentration (ppm) of 14C-Hexachlorobenzenea and Its Metabolites 1n Sprague-Dawley Ratsb
Tissue
Stomach
Duodenum
i^ Jejuno-Ileum
01 Cecum
Colon
Liver
Mesenterlc
lymph node
Adipose
tissue
Kidneys
Lungs
Male
0.6
0.6
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
1
F ema 1 e
1.6
0.6
0.2
0.1
0.1
0.4
0.6
0.2
0.2
0.3
Male
0.8
1.4
0.6
0.1
0.1
0.5
0.4
1.7
0.4
0.3
3
F ema 1 e
1.0
1.0
0.8
0.2
0.2
0.5
1.3
1.2
0.3
0.4
Time I
Male
1.1
0.2
1.0
0.1
0.4
0.2
2.0
2.3
0.5
0.2
[hours)
5
Female
0.5
0.3
0.3
0.1
0.1
0.3
1.0
1.5
0.2
0.2
1
Male
0.1
0.1
0.3
0.1
0.1
0.2
1.5
1.3
0.2
0.1
12
Female
0.1
0.1
0.3
0.2
0.1
0.2
1.0
1.1
0.1
0.1
48
Male
0.1
0.1
0.2
0.1
0.2
0.1
1.9
2.6
0.2
0.1
Female
0.1
0.1
0.1
0.1
0.1
0.2
2.1
2.7
0.1
0.2
o
CO
PO
CO
03
a!50 yg hexachlorobenzene was administered by stomach tube suspended 1n 1% methyl cellulose.
^Source: latropoulos et al., 1975
-------
TABLE 12-3
Tissue Levels of HCB (ppm) 1n Adult Female Rhesus Monkeys3'*3
Monkey No.
Dose (mg/kg/day)
Body fat
Bone marrow
Adrenal cortex
Adrenal medulla
Liver
Kidney
Brain
Ovaries
Muscle
Serum
61 3C
128
930
460
150
12
20
18
25
6
4
2.5
618d
128
215
175
30
9
50
19
19
23
21
1.5
627e
64
540
1700
325
285
365
258
108
133
24
11.0
817
32
250
255
90
35
40
11
12
3
7
0.5
1163
8
580
350
50
4
30
3
8
1
2
3.3
1826
0
1.1
1.6
0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
aSource: Knauf and Hobson, 1979
bHCB was administered dally for 60 days 1n IX methylcellulose
cMonkey was small and slight
^Monkey was obese
eMonkey had very little adipose tissue
HCB = Hexachlorobenzene
1835A 12-7 03/30/84
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The highest levels of hexachlorobenzene residues were found 1n fat tis-
sue (215-930 ppm) and bone marrow (175-1700 ppm), and selectively higher
levels were found 1n the adrenal cortex (30-325 ppm) than 1n the adrenal
medulla (4-285 ppm). Residues 1n semen, muscle, ovaries, brain, kidneys and
liver were relatively much lower (0.5-258 ppm).
Engst et al. (1976) reported the administration by gavage of 8 mg/kg of
hexachlorobenzene 1n 1 ml of sunflower oil to male Wlstar rats for 19
days. The animals were then sacrificed, and the liver, kidneys, adrenals,
heart, spleen and Intestinal fat were analyzed for hexachlorobenzene resi-
dues. The following results were reported: fat tissue, 82 yg/g; muscle,
17 yg/g; liver, 125 vg total; kidneys total 21 vg each; spleen total 9
pg; heart total 1.5 pg; and adrenals total 0.5 ug each. High levels
of hexachlorobenzene residues 1n fat tissues also have been reported for
rats receiving 50.0 mg/kg (177 ymoles/kg) of hexachlorobenzene every
second day for 10 weeks (Koss et al., 1980b).
Szymczynskl and Wal1szewsk1 (1981) analyzed human semen and testlcular
and fat tissues, and Identified several chlorinated pesticides that Included
hexachlorobenzene. The compound was not detected 1n testlcular tissue, but
was present 1n semen and fat tissues at concentrations of 0.001 and 0.128
vig/g, respectively. Similarly, hexachlorobenzene was one of several
chlorinated compounds found 1n semen collected 1n 1979 from 132 college
students (Dougherty et al., 1981).
Sundlof et al. (1982) studied the distribution of 14C-hexachloroben-
zene or unlabeled hexachlorobenzene 1n male beagles following a single
Intravenous dose of 1 mg/kg 1n olive oil. Two dogs each were sacrificed
after 2, 4, 8, 16, 32 and 48 hours and after 12 weeks; hexachlorobenzene
concentrations were determined 1n 16 tissues and organs as well as 1n the
blood (Table 12-4). Two hours after dosing, the highest concentration
1835A 12-8 03/30/84
-------
TABLE 12-4
HCB Concentrations In Tissues of Male Beagles
Receiving Single Intravenous Doses of 1 mg/kg bw 1n 011ve 011*
Tissue
Lungs
Adrenals
Subcutaneous fat
Perlrenal fat
MesenteMc fat
Spleen
Liver
Thyroid
Heart
Kidneys
Stomach
Pancreas
Brain
Duodenum
Colon
Small Intestine
Blood
2 hours
36.14
2.82
1.14
1.00
0.56
0.54
0.51
0.37
0.28
0.18
0.18
0.17
0.15
0.12
0.12
0.07
0.07
HCB Concentration (ppm)
Time Interval After Dosing
48 hours
0.08
0.38
3.38
3.24
2.40
0.01
0.04
NR
0.04
0.02
0.36
0.06
0.02
0.02
0.01
0.02
0.03
12 weeks
<0.01
0.06
0.37
0.46
0.41
<0.01
0.02
0.02
0.01
0.01
0.01
0.07
0.02
0.02
<0.01
0.01
0.01
*Source: Sundlof et a!., 1982
NR - Not reported
HCB - Hexachlorobenzene
1835A
12-9
03/23/84
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was found 1n the lungs (36.14 ppm). This was considered to be a property of
the Injection vehicle rather than a property of hexachlorobenzene per se.
That 1s, H was believed that the olive oil vehicle formed m1croembol1 1n
the blood which became trapped 1n the capillaries of the lung. Residue
levels 1n the lungs then dropped (4.4 ppm), and a concurrent Increase 1n
hexachlorobenzene was detected 1n fat tissues (10.32 ppm 1n subcutaneous,
perlrenal and mesenterlc fat) 4 hours postlnjectlon. Residues In all
tissues, organs and blood declined during the 48 hours postlnjectlon except
for fat tissue, which remained constant. Twelve weeks after dosing, tissue
concentrations were very low 1n all tissues, Including fat (>0.01-0.46 ppm),
Indicating significant excretion of the compound.
Yang et al. (1978) studied the distribution of hexachlorobenzene 1n male
Sprague-Oawley rats and female rhesus monkeys following Intravenous Injec-
tion of 14C-hexachlorobenzene 1n 1,2-propaned1olrplasma (1:8). Rats
received 0.1 mg of 14C-hexachlorobenzene and then were replaced In meta-
bolic cages for 48 hours before sacrifice. About 0.2 and 1.0% of the admin-
istered dose was excreted 1n the urine and feces, respectively. No radio-
activity was exhaled from the animals. Over 20 tissues from the rats were
analyzed and all were found to contain radioactivity. The highest levels
were In fat (~3 yg/g of tissue). The adrenal glands also contained a
relatively high level of radioactivity, whereas the other tissues contained
much lower levels, generally 1n the range of 1/12 to 1/300 of those 1n fat
tissue.
The tissue distribution of 14C-hexachlorobenzene 1n rhesus monkeys was
determined 1n Individual animals 100 days, 6 months and 1 year after Intra-
venous Injection of 14C-hexachlorobenzene at 0.38, 0.32 and 0.22 mg/kg,
1835A 12-10 03/30/84
-------
respectively. The results again Indicated that the highest levels were
present 1n fat (828-6069 ng/g) and bone marrow (373-1638 ng/g) among the 30
tissues analyzed 1n all three monkeys. The adrenal glands contained -1/6 to
1/8 of the levels present 1n fat, whereas the other tissues contained radio-
activity levels ranging between 1/10 to <1/800 of those 1n fat.
The transplacental transfer of hexachlorobenzene from pregnant mice,
rats and rabbits has also been reported. Brandt et al. (1980) conducted a
qualitative study on the distribution of 14C-hexachlorobenzene and several
of Us sulfur-containing metabolites 1n pregnant mice. The mice were
Injected 1.v. and sacrificed at Intervals ranging between 20 minutes and 32
days after Injection. The animals were frozen, sectioned and submitted to
autoradlography. The autoradlograms showed a strong uptake of hexachloro-
benzene 1n the adipose tissues. This hexachlorobenzene was found to persist
1n the adipose tissues for more than 1 month after the administration.
Radioactive hexachlorobenzene was also found to penetrate the placenta,
resulting 1n the blood and liver concentrations 1n the fetus equaling those
of the dams.
Vllleneuve and H1erl1hy (1975) studied the placental transfer of hexa-
chlorobenzene 1n Wlstar rats and reported that hexachlorobenzene crosses the
placenta and accumulates 1n the fetus 1n a dose-dependent manner. The
females were dosed dally (5, 10, 20, 40 and 80 mg/kg) from gestation day
6-16 and then sacrificed on day 22. Only liver, brain and whole fetus resi-
due levels were determined 1n this study. Fetal liver residues (1.8-35.8
pg/g) were much lower than those of the dams (9.3-86.0 pg/g). The fetal
brain and whole fetus levels were 1.1-17.5 pg/g and 1.5-18.9 pg/g,
respectively.
1835A 12-11 03/23/84
-------
vnieneuve et al. (1974) also reported that the transplacental transport
of hexachlorobenzene 1n New Zealand rabbits was dose-dependent. Rabbits
were mated and then treated orally with hexachlorobenzene from days 1-27
with subtoxlc doses of 0, 0.1, 1.0 or 10 mg/kg. On day 28 the dams were
killed for fetal and maternal tissue analysis for hexachlorobenzene. In
dams, the hexachlorobenzene residue concentrations were highest 1n fat,
followed by the liver, heart, kidneys, brain, lung, spleen and plasma.
Hexachlorobenzene residues were higher 1n the fetal liver than In the
maternal liver.
Courtney et al. (1976) reported on the distribution of hexachlorobenzene
(assayed 90.4% hexachlorobenzene and 9.6% pentachlorobenzene) administered
on days 7-11 of gestation at a dose of 50 mg/kg/day 1n a corn oil acetone
mix to five pregnant and two non-pregnant CD-I mice. They found there were
no remarkable differences 1n the hexachlorobenzene tissue levels between the
pregnant and non-pregnant animals sampled at day 12 of pregnancy. The
levels of pentachlorobenzene 1n sampled tissues were low as compared to the
very high hexachlorobenzene levels detected 1n the thymus, skin, fat and
urinary bladder. No detectable levels of hexachlorobenzene or pentachloro-
benzene were found 1n the control mice.
Courtney et al. (1979) studied the tissue distribution of hexachloroben-
zene 1n the maternal and fetal tissues of CO rats and CD-I mice and reported
that placentas and fetuses of both species demonstrated a dose-dependent
relationship for hexachlorobenzene residues, with levels 1n the fetuses
being higher than those 1n their corresponding placentas. The dams were
treated with single or multiple oral doses (10, 50 or 100 mg/kg 1n corn oil)
at different periods during gestation. The hexachlorobenzene concentrations
1835A 12-12 03/23/84
-------
1n mice and rat fetuses at mid-gestation were very similar. In mice, mul-
tiple low doses of hexachlorobenzene resulted 1n higher concentrations of
hexachlorobenzene 1n maternal and fetal tissues than single doses of equiva-
lent total doses. In another study, Courtney and Andrews (1979) reported
that 1n mice the fetus could be exposed to hexachlorobenzene from maternal
body burdens, established before fetal Implantation, and was not limited to
maternal exposure during the postlmplantatlon gestation.
Bleavlns et al. (1982) studied the tissue distribution and transfer of a
single dose of hexachlorobenzene given to female European ferrets (Mustela
putorlus furo). They gave a single 57.6 yg hexachlorobenzene (14C-
labeled) dose to each of three bred and five non-bred ferrets, 1n 7.5 g of
standard mink diet (22.2% fat). The dosed ferrets and offspring were
observed for 5 weeks after the kits were born, at which time they were
killed and tissue 14C-hexachlorobenzene levels were determined (Table
12-5). One ferret kit per Utter was also collected at birth and at weeks
1, 2, 3 and 4 for whole body residue determinations (Table 12-6). These
results Indicate that nursing mothers can significantly reduce their body
burdens of hexachlorobenzene, when compared to unbred female counterparts,
by transferring a large amount of the hexachlorobenzene to their offspring.
The mothers' milk contaminated with hexachlorobenzene seems to be a large
contributor to the kits' body burdens with a reported milk to placental
exposure ratio of 31:1. The distribution of hexachlorobenzene 1n ferrets
follows similar trends, as observed 1n the other mammals, of the highest
hexachlorobenzene levels being found 1n the I1p1d rich tissues.
The transfer of hexachlorobenzene to nursing Infant rhesus monkeys from
lactatlng mothers receiving 64 mg/kg/day for 60 days was reported by Bailey
et al. (1980). M1lk concentrations were on the average 17-fold higher than
1835A 12-13 03/30/84
-------
TABLE 12-5
Mean (+SE) Hexachlorobenzene Radioactivity (dpm/g)
of Selected European Ferret T1ssuesa»D
Tissues
Blood
Subcutaneous fat
Visceral fat
Muscle
Heart
Kidney
Spleen
Liver
Lung
Brain
Group I
(n=3)
49
4472
4429
53
34
105
13
248
1
61
1 34. 6d
i 780.5s
1 867.6s
i 14. 4d
1 9.2d
1 31.1s
± 7.5s
± 68.9s
1 0.3s
1 30.0s
Group II
(n=5)
166
19,525
19,704
384
310
611
180
1,445
241
395
t 26.8
i 1503.9
+ 1666.0
i 64.0
i 56.8
± 80.4
1 24.8
i 145.2
i 18.4
± 48-5
K1tsc
(n=3)
—
11,678 i 712. 4f
--
561 i 204.8
--
209 i 37.2
--
1,420 i 185.69
---
130 + 29.4
aSource: Bleavlns et al., 1982
bat 62 days postdoslng from adult bred (group I) and unbred (group II)
female ferrets exposed to a single 57.6 yg dose of 14C-labeled hexa-
chlorobenzene and from offspring born to the bred females.
CKH tissues, from 5-week-old offspring, were contrasted only with mater-
nal (group I) tissues.
dS1gn1f1cantly different (p<0.05) from group II tissue of the same type.
6S1gn1f1cantly different (p<0.01) from group II tissue of the same type.
^S1gn1fIcantly different from maternal tissue (group I) at p<0.01.
9S1gn1f1cantly different from maternal tissue (group I) at p<0.05.
HCB =- Hexachlorobenzene
1835A 12-14 03/23/84
-------
CO
GO
en
3>
ro
i
TABLE 12-6
Mean (+SE) HCB Radioactivity (dptn x 10») of European Ferret KHsa-b
Weeks Post par turn
Measure Number
Per gram of kit 3
Per whole kit 3
Increase over previous week
M1lk (per ml) 3
0 1 2
3.0 i 0.19 2.7 i 0.57 4.3 + 0.67
25. 111. 43 76.7 i 14.35 311.4+63.39
51.6 234.7
6.1 t 0.66
3
3.9 i 0.73
492.5 + 92.22
181.1
2.9 t 0.45
4
3.5 ±
672.8 +
180.
1.8 ±
0.50
117.63
3
0.17
5
2.7 i
805.7 *
132.
0.8 *
0.14
54.25
.8
0.20
aSource: Bleavlns et al., 1982
bBorn to female ferrets exposed to a single dose of 14C-labeled hexachlorobenzene and the milk produced by those dams
HCB =- Hexachlorobenzene
o
CO
00
\
co
-------
maternal serum levels, whereas Infant serum levels were about 2- to 5-fold
higher than serum levels of their mothers. Similarly, the Infants had
higher tissue residues than their mothers and hexachlorobenzene was concen-
trated 1n the Infant fat, bone marrow, adrenals and lymph nodes.
Hexachlorobenzene residues also have been reported 1n human fat 1n the
United Kingdom (Abbott et al.9 1981, Japan (Curley et al., 1973), and
Australia (Brady and S1yal1, 1972) and in human milk collected 1n Sweden
(Westoo and Noren, 1978; Hofvander et al., 1981), Canada (Mes and Davles,
1979), Norway (Bakken and Se1p, 1976; Skaare, 1981), and Hawaii (Takahashl
et al., 1981).
12.1.3. Metabolism. The metabolism of hexachlorobenzene has been studied
1n male and female rats following oral administration, rhesus monkeys and
beagles following i.v. injection, and rabbits following i.p. Injection
(Renner, 1981). Hexachlorobenzene 1s metabolized slowly into other chlori-
nated benzenes, chlorinated phenols and other minor metabolites and forms
glucuronide and glutathlone conjugates. Tissues were found to contain
mainly unchanged hexachlorobenzene together with small amounts of metabo-
lites. Similarly, only small amounts of hexachlorobenzene metabolites were
detected in feces, whereas most of the metabolites were excreted In the
urine together with small amounts of unchanged hexachlorobenzene.
Mehendale et al. (1975) studied the metabolism of hexachlorobenzene in
male Sprague-Dawley rats 7 days after oral administration of a single 5
mg/kg dose. The fat, liver, intestines, kidneys, lungs and brain were found
to contain hexachlorobenzene primarily, along with trace amounts of other
chlorinated benzenes. Analysis of these chlorinated benzenes suggested the
presence of pentachlorophenol, 2,4,5-trlchlorophenol, pentachlorobenzene and
the tetrachlorobenzenes. Extraction and analysis of fecal radioactivity,
1835A 12-16 03/30/84
-------
which accounted for 16% of the dose, did not reveal the presence of metabo-
lites. Although urine contained only 0.85% of the administered radioactiv-
ity, 1t provided the only evidence of hexachlorobenzene metabolite excre-
tion. Several unidentified metabolites were evident following thin-layer
chromatography (TLC) separation of urine, 1n addition to 2,4,5-tMchloro-
phenol, pentachlorophenol and one spot was reported to contain a mixture of
chlorinated benzenes.
^n vitro metabolism studies with homogenates of the liver, lungs, kid-
neys and small Intestines produced trace amounts of chlorobenzene metabo-
lites when Incubated with [14C]-hexachlorobenzene 1n the presence or
absence of added cofactors. Liver mlcrosomal preparations produced amounts
of one or more chlorophenols when fortified with NADPH; 1n the presence of
UDPGA, pentachlorophenol was reported to form the glucuronlde conjugate.
Fortification of kidney homogenates with glutathlone resulted 1n the appear-
ance of unextractable radioactivity 1n the aqueous phases, Indicating that
glutathlone conjugates of polar hexachlorobenzene metabolites might also be
formed (Mehendale et al., 1975).
The metabolism of hexachlorobenzene 1n male and female Sprague-Dawley
rats each receiving nine doses of 85.6 mg/kg hexachlorobenzene (99.7% pure)
1n arachls oil over a period of 1 month was reported by Rlchter et al.
(1981). The animals were sacrificed 3, 24 and 52 days after the last dose,
and various tissues were analyzed for hexachlorobenzene and Us metabolites
by CDE/6LC and GLC/MS. In addition to hexachlorobenzene, the following
metabolites were also detected: pentachlorobenzene (PCB), pentachlorophenol
(PCP), pentachlorothlophenol (PCTP) and 2,3,4,6- and 2,3,5,6-tetrachloro-
phenol (TCP). The results reported for the liver and kidneys for day 3
Indicated that the livers of the females contained significantly more PCTP,
1835A 12-17 03/23/84
-------
a derivative of a glutathlone conjugate, than those of the males (Table
12-7). However, 1t 1s not known whether that Increase 1s due to a higher
rate of PCTP production or to a lower rate of elimination.
R1zzard1n1 and Smith (1982) Investigated the sex differences 1n hexa-
chlorobenzene metabolism 1n young F344/N rats who had been Intubated every
other day for 103 days with 14 mg/kg hexachlorobenzene (analytical grade)
dissolved In arachls oil. Three hexachlorobenzene metabolites were analyzed
for: pentachlorobenzene, pentachlorothlophenol and 2,3,5,6-tetrachloroben-
zene-1,4-d1ol, and all three were found to be produced In larger concentra-
tions 1n the female rats during the first 10 weeks of hexachlorobenzene
treatment. The greater quantities of hexachlorobenzene metabolites being
formed In female rats was believed due to their body estrogen levels.
Engst et al. (1976) detected several urinary metabolites 1n male Wlstar
rats receiving by gavage 8 mg/kg of hexachlorobenzene dally dissolved 1n
sunflower oil for 19 days. The results of this study were presented quali-
tatively, and the authors reported that the major metabolic route for hexa-
chlorobenzene was to pentachlorophenol. In addition, the feces contained
mainly unchanged hexachlorobenzene together with traces of pentachloro-
benzene.
Koss et al. (1976) Investigated the metabolism of hexachlorobenzene In
female Wlstar rats given 2-3 1.p. doses of [14C]hexachlorobenzene (260 or
390 mg/kg total dose). At the end of 4 weeks, 1% of the administered radio-
activity was excreted 1n the urine, with >90% of this amount contained 1n
the major metabolites (pentachlorophenol, tetrachlorohydroqulnone, and
pentachlorothlophenol). An Isomer of tetrachlorothlophenol was detected as
a minor urinary metabolite. Twenty-seven percent of the administered radio-
activity was excreted 1n the feces, of which 70% was Identified as unchanged
1835A 12-18 03/23/84
-------
TABLE 12-7
Concentrations of HCB and Its Metabolites (mg/kg)
1n the Liver and Kidneys of Male and Female Ratsa»b
Tissue/Sex
Liver
Males
Females
Kidneys
Males
Females
HCB
192
147C
127
111
PCB
0.05
0.03C
0.05
0.01
PCP
3.16
2.12C
5.79
3.69
PCTP
0.23
0.36C
0.24
0.10
TCP
0.02
0.04C
0.09
0.08
aSource: Rlchter et al., 1981
bDeterm1ned 3 days after the last of nine oral doses of 85.6 mg/kg HCB
given within 1 month 1n arachls oil
Statistically significant from males (p<0.05)
HCB = Hexachlorobenzene; PCB = pentachlorobenzene; PCP = pentachlorophenol;
PCTP - pentachlorothlophenol; TCP = 2,3,5,6-tetrachlorophenol
1835A 12-19 03/23/84
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hexachlorobenzene. Only pentachlorophenol and pentachlorothlophenol were
Identified as fecal metabolites of hexachlorobenzene. In the tissues of the
animals, only pentachlorophenol was detected 1n measurable quantities,
accounting for 10% of the radioactivity 1n blood and <0.1% In body fat.
Total radioactivity contained 1n the metabolites detected in the animal
bodies and excreted at the end of the 4 weeks accounted for 16% of the
administered radioactivity.
In follow-up studies, Koss et al. (1978a) compared the formation of
hexachlorobenzene metabolites 1n rats, mice, guinea pigs, Japanese quail,
laying hens and rainbow trout. The only metabolites detected were penta-
chlorophenol, tetrachlorohydroqulnone and pentachlorothlophenol; however,
the species tested differed greatly in their ability to metabolize hexa-
chlorobenzene (Table 12-8).
Gas-liquid chromatography of urine, bile and fecal extracts from male
beagle dogs receiving a single i.v. injection of 14C~hexachlorobenzene at
1 mg/kg revealed that 96% of the fecal radioactivity occurred as the parent
compound. Hexachlorobenzene accounted for 4% of the biliary radioactivity,
but no parent compound was detected in urine (Sundlof et al., 1982).
Kohli et al. (1976) studied the metabolism of several chlorinated ben-
zenes, Including hexachlorobenzene, in rabbits following 1.p. injection.
The urine was collected for 10 days after injection and analyzed for metabo-
lites following extraction and gas-liquid chromatography, but no hexachloro-
benzene metabolites were found 1n the urine.
12.1.4. Excretion. The excretion of hexachlorobenzene from treated ani-
mals 1s slow and occurs mainly through the feces, with relatively little
being excreted 1n the urine. It 1s characterized by an initial rapid phase
followed by a very slow phase. This slow phase of excretion can be enhanced
1835A 12-20 03/23/84
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TABLE 12-8
Hexachlorobenzene and Its Major Metabolites
1n the Excreta of Different Animal Species3
Spec1esb
Rat
Mouse
Guinea pig
Japanese quail
Laying hen
Rainbow trout
Total Dose
(mMol/kg)
0.92
0.92
0.92
2.76
0.92
2.76
HCB
6.1C
2.6
1.8
7.5
0.6
1.8
Total Amount
PCP
2.0
0.3
0.9
trace
0.1
0.4
of Substances
TCH
0.4
0.1
0.2
trace
0.07
ND
PCTP
1.8
ND
0.5
3.2
0.04
ND
aSource: Koss et al., 1978a
^2-3 animals were used per each species Investigated
cF1gures are given 1n yMol/kg bw/day
ND = Not detected. The lower detection limit of the metabolites was deter-
mined to be 0.03 nMol/ms. urine or g feces.
HCB = Hexachlorobenzene; PCP = pentachlorophenol; TCH = tetrachlorohydro-
qulnone; PCTP = pentachlorothlophenol
1835A
12-21
03/23/84
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by the administration of mineral oil, paraffin and n-hexadecane. Both
biliary and Intestinal excretion contribute to fecal excretion. A three-
compartment mammalian model has been reported for the behavior of hexa-
chlorobenzene 1n beagles and rhesus monkeys following 1.v. Injection of a
single dose. Radioactivity was not detected 1n exhaled air following 1.p.
Injection of 14C-hexachlorobenzene.
Studies conducted by Mehendale et al. (1975) with rats receiving a
single oral dose Indicated that only 16.0 and 0.85% were excreted 1n the
feces and urine, respectively, 7 days after treatment (see Table 12-1).
IngebHgtsen et al. (1981) reported that 4 days after 1ntragastr1c admin-
istration of 14C-hexachlorobenzene, a total of 24.8 and 2.1% of the admin-
istered radioactivity were recovered 1n the feces and urine, respectively.
In addition, an average of 3.6% of the dose was recovered 1n the bile of
blle-duct-cannulated rats within 48 hours after dosing. Of the radioactiv-
ity excreted In the bile, only 2% was unchanged hexachlorobenzene, 1.8% was
pentachlorobenzene, 24% was pentachlorophenol and -72% was unidentified
metabolites.
Rozman et al. (1977) studied the excretion of hexachlorobenzene 1n
female rhesus monkeys receiving 110 yg 14C-hexachlorobenzene/day/monkey
via diet for 15 months. The excretion and storage patterns showed a very
slow approach to a saturation level, Indicating a high tendency for hexa-
chlorobenzene accumulation 1n rhesus monkeys. A total of 5.8 and 3.6% of
the administered dose was excreted 1n the urine of male and female monkeys,
respectively, after 15 months, of which 50% was pentachlorophenol, 25%
1835A 12-22 03/23/84
-------
pentachlorobenzene and the remaining 25% consisting of unidentified metabo-
lites with varying amounts of hexachlorobenzene. A total of 47.9 and 27.5%
of the dose was present 1n the feces of male and female monkeys, respec-
tively, of which 99% was hexachlorobenzene.
Koszo et al. (1978) administered hexachlorobenzene (0.2% 1n the diet) to
young male and female Wlstar rats for as long as 200 days and measured the
accumulation of hexachlorobenzene 1n the liver and fatty tissue and the
excretion of hexachlorobenzene and pentachlorophenol 1n the urine and feces.
The concentration of hexachlorobenzene 1n the liver and fat Increased stead-
ily throughout the treatment period. Pentachlorophenol appeared 1n both the
urine and feces 1n Increasing amounts throughout the treatment period, with
the excretion of other apolar and polar products being markedly enhanced
after 5-6 weeks.
R1zzard1n1 and Smith (1982) Investigated the sex differences 1n hexa-
chlorobenzene metabolism and excretion of hexachlorobenzene metabolites 1n
young F344/N rats. These rats were Intubated with 14 mg/kg analytical grade
hexachlorobenzene dissolved 1n arachls oil every other day for 103 days and
were analyzed for the three main hexachlorobenzene metabolites, pentachloro-
phenol, pentachlorothlophenol and 2,3,5,6-tetrachlorobenzene-l,4-d1ol, 1n
urine and feces. Results Indicated that the combined urinary excretion of
metabolites was greater 1n the female rats, especially during the first 10
weeks, with pentachlorothlophenol being particularly high In the females.
No wide variations between the sexes were seen 1n the analyzed feces hexa-
chlorobenzene metabolites after 103 days of treatment. Combined urine and
feces excretion of metabolites at the end of the study were found not to be
significantly different between males (229H116 nmole/ 24 hours/kg) and
1835A 12-23 03/23/84
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females (2425tl82 nmole/24 hours/kg). It was stated, though, that the total
excretion of pentachlorothlophenol was always significantly higher 1n the
female rats.
Koss and Koransky (1975) studied the metabolism of hexachlorobenzene 1n
rats when the compound was orally administered 1n an aqueous suspension or
1n olive oil. The animals received different amounts of 14C-hexachloro-
benzene 1n a single dose, and the feces and urine were collected at varying
time Intervals and radloassayed. When administered 1n water, hexachloro-
benzene was not readily absorbed; 76-97% of the dose was excreted 1n the
feces, and <0.1-0.4% was excreted 1n the urine 1 day after administration.
When administered 1n oil, only 45-46% of the dose was excreted 1n the feces
and 2.1-3.8% was excreted 1n the urine after 14 days of treatment. Rats
receiving 4 mg/kg of 14C-hexachlorobenzene administered 1.p. excreted a
total of 5 and 34% of the dose 1n the urine and feces, respectively, within
14 days. About 4 and 80% of the excreted radioactivity In the urine and
feces, respectively, was unchanged hexachlorobenzene. Animals Injected 1.p.
with 50.5 mg/kg [14C]hexachlorobenzene released no radioactivity 1n
exhaled air (Koss and Koransky, 1975).
Rozman et al. (1981) reported that administration of mineral oil or
n-hexadecane to female Sprague-Dawley rats or male or female rhesus monkeys
who were pretreated with 14C-hexachlorobenzene enhanced the fecal elimina-
tion of 14C-hexachlorobenzene. All animals were administered 14C-hexa-
chlorobenzene (100 mg/kg) orally as a single dose except for one monkey that
received three consecutive dally doses and two monkeys that received 14C-
hexachlorobenzene (0.11 mg/kg) 1n sugar pellets dally for 750 consecutive
days. Aliphatic hydrocarbons were administered to the treated animals 11-40
days after hexachlorobenzene treatment. When mineral oil was added to the
1835A 12-24 03/23/84
-------
diet of the rhesus monkeys, fecal excretion was enhanced 6- to 9-fold.
Similarly, dietary administration of hexadecane resulted 1n the same
Increase 1n fecal excretion of hexachlorobenzene 1n both the rhesus monkeys
and rats. Residue analyses Indicated an enhanced depletion of hexachloro-
benzene from blood and of stored hexachlorobenzene from adipose tissue.
Enhanced fecal excretion of hexachlorobenzene as a result of dietary admin-
istration of aliphatic hydrocarbons was primarily due to Increased hexa-
chlorobenzene elimination 1n the large Intestine.
Rlchter and Schafer (1981) studied the Intestinal excretion of hexa-
chlorobenzene In male Sprague-Oawley rats using the pendular perfuslon
method. The animals were Injected 1.p. with hexachlorobenzene at 100 mg/kg
and, 1 and 4 weeks after treatment, various parts of the Intestines were
perfused with paraffin or squalane for 5 hours. The largest amount of hexa-
chlorobenzene excreted was Into the jejunum followed by the 1leum and
colon. The ratios of total hexachlorobenzene excreted during paraffin
treatment were: jejunum/1leum = 1.26 and jejunum/colon = 2.43. The authors
concluded that these results Indicate the Importance of Intestinal excretion
1n the elimination of hexachlorobenzene, and that paraffin treatment can be
one of the measures by which a long-term stimulation of hexachlorobenzene
excretion can be achieved.
Beagle dogs receiving a single 1.v. dose of 1 mg/kg excreted 44 and <6%
of the dose 1n the feces and urine, respectively, during a 12-week period
(Sundlof et al., 1982). Both biliary and Intestinal excretion contributed
to fecal excretion; however, the data Indicated that biliary excretion was
the major contributor to fecal excretion. A computer-assisted pharmaco-
klnetlc analysis of blood, urine and fecal radioactivity levels during a
1835A 12-25 03/23/84
-------
12-week period suggested a three-compartment model for the behavior of hexa-
chlorobenzene 1n beagles. The biological half-life values were calculated
for the three dogs used and ranged from 6 weeks to 3 years.
Yang et al. (1978) reported that the elimination rate of hexachloroben-
zene from male Sprague-Dawley rats and rhesus monkeys Injected 1.v. with
hexachlorobenzene was slow because hexachlorobenzene 1s stored In the fat
tissue. The major route of radlolabel excretion 1n treated monkeys was via
the feces. About 17.1, 8.8 and 28.2% of the dose was excreted In the feces
after 100 days, 6 months and 1 year, respectively, after treatment of Indi-
vidual monkeys, with -90% of the radioactivity determined to be unchanged
14C-hexachlorobenzene. The cumulative urinary excretion of hexachloroben-
zene metabolites was determined to be 1.6% of the administered dose after 1
year. An open system, three-compartment mammUlary model was found to fH
the data for plasma, fecal and metabolized hexachlorobenzene 1n the rhesus
monkey.
Koss et al. (1983) administered 100 mg/kg hexachlorobenzene every other
day, via stomach tube, to female Wlstar rats for a period of 6 weeks and
then observed the rats for an additional 18 months. At cessation of hexa-
chlorobenzene treatment they tried to assess the biological half-life of
hexachlorobenzene and determined a value of 8 days for the start of the
elimination phase, a value of 10 weeks when assessed 3 months later, and
finally a value of 1.5 years after 12 months. The authors then concluded
that 1t 1s not possible to establish a valid biological half-life for the
total elimination phase of hexachlorobenzene 1n rats.
Bleavlns et al. (1982) studied the excretion and transfer of hexachloro-
benzene given to female European ferrets (Hustela putorlus furo). Three
bred and five non-bred female ferrets were each given a single dose of 57.6
1835A 12-26 03/30/84
-------
yg 14C-hexach1orobenzene 1n 7.5 g of standard mink diet (22.2% fat).
The Investigators Indicated that there were no significant differences 1n
the excretion of hexachlorobenzene metabolites, between bred and non-bred
groups, 1n urine for the entire 8-week study period or 1n feces during the
beginning of the study. The observed fecal excretion during the middle
weeks to the end of the study showed a leveling of the cumulative fecal
excretion 1n the bred females and a continued Increase 1n fecal excretion 1n
the non-bred female ferrets, although 1t was stated that this difference was
not statistically significant. Excretion of hexachlorobenzene or metabo-
lites 1n the milk was found to be an Important route of excretion for lac-
tatlng females, -20.3% of the Initial dose was eliminated by the fifth week
of lactation, and found to be a very Important route of exposure to nursing
offspring. The Importance of placenta! transfer and milk excretion 1s fur-
ther presented by observing the time required for 50% of the Initial hexa-
chlorobenzene dose to be excreted. The bred females required 32 days to
excrete 50% while 41 days was required for the unbred females.
12.1.5. Summary. The pharmacoklnetlcs of hexachlorobenzene 1n a number of
mammalian species have been studied 1n detail following oral administration
and, to a lesser extent, following 1.v. or 1.p. Injection. No Information
was present 1n the available literature on hexachlorobenzene metabolism fol-
lowing Inhalation or topical application. Absorption of hexachlorobenzene
from the Intestinal tract appears to depend on the solvent vehicle used dur-
ing test material administration. Thus, when hexachlorobenzene 1s admin-
istered 1n olive oil, -80% of the dose 1s absorbed; when H 1s administered
1n an aqueous solution, 1n 1% methyl cellulose or 1n a crystalline form,
relatively little (<20%) 1s absorbed. Intestinal absorption of hexachloro-
benzene occurs primarily through lymphatic channels, with only a minor por-
tion being absorbed Into the portal circulation.
1835A 12-27 03/30/84
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Following absorption, hexachlorobenzene distributes to tissues that have
a high I1p1d content. The adipose tissue accumulates the greatest concen-
trations of hexachlorobenzene 1n all species studied, although bone marrow
and skin, which contain large amounts of liplds, also accumulate hexachloro-
benzene. The adrenal cortex accumulates hexachlorobenzene at concentrations
approaching those of fat. Other tissues (e.g., kidneys, lungs, heart,
spleen and blood) generally contain much lower amounts of hexachlorobenzene.
Intravenous Injection of hexachlorobenzene results 1n a tissue distribution
similar to that seen following oral administration. Hexachlorobenzene Is
transported via the placenta and 1s distributed in fetal tissue in rabbits,
rats, mice, minks and ferrets.
Hexachlorobenzene 1s metabolized slowly into other chlorinated benzenes,
chlorinated phenols and other minor metabolites and forms glucuronide and
glutathione conjugates. Tissues were found to contain mainly unchanged
hexachlorobenzene together with small amounts of metabolites. Similarly,
only small amounts of hexachlorobenzene metabolites were detected in feces,
whereas most of the metabolites were excreted in the urine together with
small amounts of unchanged hexachlorobenzene. There are indications that
females produce and excrete more hexachlorobenzene metabolites than do males.
The excretion of hexachlorobenzene from treated animals 1s slow and
occurs mainly through the feces with relatively little being excreted 1n the
urine. It 1s characterized by an initial rapid phase followed by a very
slow phase. This slow phase of excretion can be enhanced by the administra-
tion of mineral oil, paraffin or n-hexadecane. Both biliary and intestinal
excretion contribute to fecal excretion. A three-compartment mammlllary
model has been reported for the behavior of hexachlorobenzene 1n beagles and
rhesus monkeys following 1.v. injection of a single dose. Radioactivity was
1835A 12-28 03/30/84
-------
not detected 1n exhaled air following 1.p. Injection of 14C-hexachloroben-
zene. Hexachlorobenzene has been detected 1n the milk of nursing mammals
(see Sections 12.1.2. and 12.2.).
12.2. EFFECTS ON HUMANS
The effects of hexachlorobenzene on humans as a result of accidental or
occupational exposure have been reviewed by Courtney (1979) and Currier et
al. (1980). A few reports of data collected on occupatlonally exposed
workers have been reported with studies conducted 1n Turkey and In the
United States (I.e., Louisiana) on the general population following
accidental exposure to hexachlorobenzene. The exposure of humans to toxlco-
loglcally significant levels of hexachlorobenzene In Turkey from 1955-1959
by 1ngest1on of contaminated grain, as reported by Cam (1959, 1960), Cam and
Nlgogosyan (1963) and Peters (1966), caused an epidemic of hexachloro-
benzene-lnduced porphyrla cutanea tarda (PCT), also known as porphyrla
turdca.
12.2.1. Ep1dem1ologU Studies. Burns et al. (1974) found 0-310 ppb hexa-
chlorobenzene In blood samples from 20 vegetable spraymen. There were no
signs of PCT, and no correlations were observed between hexachlorobenzene
levels and urinary porphyrfn excretion, serum glutamlc-oxaloacetic trans-
amlnase, serum glutamlc-pyruvlc transamlnase or lactate dehydrogenase.
Increased levels of urinary porphyrlns were detected 1n 1 of 54 men occupa-
tlonally exposed to hexachlorobenzene (Morley et al., 1973).
A medical survey was conducted by Dow Chemical Company (Currier et al.,
1980) on 50 employees working at a chlorinated solvents plant 1n Louisiana,
to determine blood hexachlorobenzene levels and signs suggestive of PCT or
other adverse effects, as well as any changes 1n hematologlc, clinical chem-
istry and urlnalysls parameters. The results from this study are of limited
1835A 12-29 03/30/84
-------
value because the various parameters studied during the 4-year period were
analyzed by several laboratories using various methods and on different
Individuals. There was potential exposure to other substances also. During
various times of the study, the time-weighted-average airborne concentra-
tions of hexachlorobenzene ranged from <1-13 ppb, and wipe samples 1n the
control, laboratory and clerical work areas ranged from 0.03-1.24
vg/100 cm2.
The laboratory analyses and physical examinations performed on the 1977
study group and on a control group from a polyethylene plant did not reveal
any signs Indicative of PCT. Levels of hexachlorobenzene, urinary porphyMn
and coproporphyrln and the average years of exposure are listed 1n Table
12-9. A statistically significant (p<0.05) correlation was found between
hexachlorobenzene levels 1n blood and the number of years worked In the
plant. For the other studied parameters no statistically significant
differences were noted between the 44 chlorinated solvents workers and the
44 control workers for 1977, except for higher protein levels and lower
hematocrlt values 1n the former workers which were not considered to be bio-
logically significant. In addition, significantly lower levels of urinary
coproporphyrlns and albumin were detected 1n white male workers with hexa-
chlorobenzene blood levels >200 ppb than 1n those with hexachlorobenzene
levels <200 ppb.
Burns and Miller (1975) studied plasma hexachlorobenzene residues of 86
residents living and/or working 1n an area exposed to the production, trans-
portation and disposal of "hex" wastes (hexachlorobenzene and other chlori-
nated hydrocarbons) 1n Louisiana. Plasma hexachlorobenzene levels were mea-
sured and correlated with demographic characteristics, occupational hazards,
1835A 12-30 03/30/84
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TABLE 12-9
«j
op
Results of Blood and Urine Analysis 1n Men Employed In a Chlorinated Solvents Plant, 1974-19773
3>
_ Study Group _ Comparison Group
Parameter 1974 1975 1976 1977 1977
(n=50) (n=49) (n=49) (n=44) (n=44)
Blood HCB 310.7 ± 287. 7b 311. 5 + 242. 9b 159.9 + 142. 7C 170. 3+ 111. 8C 0.1 ± 0.6
Urinary 22.4+21.1 20.9+11.0 37.4+14.4 26.2+14.3 NR
uroporphyrlns
Urinary 77.4 + 40.5 67.2 + 36.1 100.6 + 40.8 95.2 + 48.9 NR
£ coproporphyrlns
Age 30.1+6.3 31.1+6.6 30.8+6.7 31.7+7.1 31.3+6.8
(years)
Plant-years 5.5 + 3.9 6.3 + 4.0 5.9 + 4.5 6.6 + 4.8 6.6 + 4.4
aSource: Currier et al., 1980; 1974-1975 results conducted by Blosdence Laboratories; 1976-1977 results
conducted by Pathology Laboratories (+_ Standard Deviation)
plasma
cln blood
0 N = Sample size
CO
g NR = Not reported
CD
* HCB = Hexachlorobenzene
-------
food sample analyses and house dust analyses. Average plasma levels of
hexachlorobenzene ranged from 2.4-3.6 ppb 1n exposed subjects as compared
with 0.5 ppb In controls (p<0.001; Table 12-10).
Higher levels of hexachlorobenzene residues, which were statistically
significant (p<0.05), were found 1n the male subjects (4.71 ppb) than 1n the
female subjects (2.79 ppb). These were not associated with race or exposure
to hexachlorobenzene through the consumption of homegrown vegetables and
animals. About 68% of the house dust samples contained an average hexa-
chlorobenzene concentration of 380 ppb as compared with 20 ppb 1n control
samples. When the hexachlorobenzene levels 1n dust were compared with the
mean plasma hexachlorobenzene residues for the same household, a significant
correlation was obtained (p<0.025). In addition, blood samples from 11
workers employed for an average of 4.8 years (10 months to 15 years) at the
chemical plant contained an average of 78.6 (14-233) ppb hexachlorobenzene.
12.2.2. Accidental Ingestlon 1n Turkey. The hexachlorobenzene-lnduced PCT
epidemic In Turkey, a result of exposure during 1955-1959 1n Individuals who
used contaminated seed wheat for food, has been reviewed by Courtney (1979).
Cam and Nlgogosyan (1963) estimated that 0.05-0.2 g of hexachlorobenzene was
consumed per day. The method of estimation was not described. PCT Is a
disease of disturbed porphyrln metabolism manifested by cutaneous lesions
and 1s commonly followed by hypertrlchosls (hairiness) and hyperplgmenta-
tlon. The Induction of porphyrla by hexachlorobenzene has been reviewed
(DeMattels, 1967; Granlck, 1965; Tschudy and Bonkowsky, 1972; Courtney,
1979). PorphyMas are metabolic disorders of porphyrln metabolism that are
characterized by Increased excretion of porphyrlns and their precursors.
Normally, i-am1nolevu!1n1c add synthetase 1s the rate-limiting step 1n
porphyrln synthesis and heme acts as an end-product Inhibitor or an end-
1835A 12-32 03/30/84
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TABLE 12-10
HCB Plasma Levels 1n Exposed Individuals and Controls3
Parameter
Number of subjects
Age (years)
Black/white ratio
HCB plasma residues (ppb)
Range (ppb)
Percent positive
Percent >1 ppb
Exposed^
86
39.8 ± 19.1
1.0
2.4 + 2.3C
0-23
99
99
Controlsb
43
32.3 ± 18.6
2.3
0.5
0-1.8
95
5
aSource: Burns and Miller, 1975
DValues are mean +_ 1 SO
cLevel for random sample only, N=63 (3.6 +_ 4.3 for random and biased
samples, N=83)
HCB = Hexaclorobenzene
1835A 12-33 03/23/84
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end-product represser of 4-am1nolevul1n1c add synthetase. In hexachloro-
benzene-lnduced porphyrla, 4-am1nolevul1n1c add synthetase 1s Induced but
heme does not suppress or Inhibit the enzyme. The activity of uropor-
phyrlnogen decarboxylase 1s decreased, consequently, porphyrln and Its pre-
cursors (e.g., uroporphyrlnogen, coproporphyrlnogen and occasionally series
I porphyMns) are excreted mainly 1n the urine but also 1n the feces.
Increased levels of porphyMns also can be measured 1n the liver, skin,
Intestinal tract and other tissues (Courtney, 1979). PCT appeared to occur
more frequently 1n children 4-16 years of age, whereas the number of adults
and children under 5 years of age reporting PCT was much lower (10-24% of
cases were Individuals over 15 years of age and <5% were children below the
age of 4). A distinct disease described as "pink sore" was observed 1n
children under 1 year of age and achieved an epidemic scale. The clinical
symptoms were weakness and convulsions and usually death 1n children whose
mothers had clinical symptoms of PCT or who had Ingested contaminated bread
during gestation and/or lactation. The presence of hexachlorobenzene 1n the
milk of nursing mothers suggested that pink sore was a manifestation of
hexachlorobenzene toxldty. The reviewer states that there was a 95% mor-
tality 1n these Infants 1n addition to the very high Incidence of still-
births.
In a follow-up study, CMpps et al. (1980) examined 32 patients 20 years
after the onset. PorphyMns were determined 1n urine and stool specimens of
29 patients and clinically significant porphyrln levels were observed 1n 5
patients. Clinical features such as hyperp1gmentat1on, scarring, pinched
fades, hypertrlchosls, enlarged thyroid and distinctive arthritis were
present 1n about half of the patients.
1835A 12-34 03/23/84
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A detailed follow-up study was also conducted with 161 Turkish patients
25 years after the Initial hexachlorobenzene Incident (Peters et al., 1982).
The patient group studied Included some of the patients previously examined
(Peters et al., 1966). Twenty-six patients were over 17 years of age at the
time of acute toxldty, whereas the average age of the remaining patients
was 7.1 years. An evaluation of the clinical signs and symptoms Is sum-
marized 1n Table 12-11.
The chronic disease state was manifested by generalized hyperplgmenta-
tlon and hypertrlchosls, scarring on the cheeks and hands, and tight sclero-
dermold changes of the nose with perloral scarring. The most striking clin-
ical features 1n those patients who developed signs of hexachlorobenzene
toxldty at an average age of 7 years consisted of painless arthritic
changes with osteoporosis of carpal, metacarpal and phalangeal bones and
atrophy or failure to develop 1n the terminal phalanges. In addition,
neurologic symptoms Including weakness, parestheslas, myotonla, cogwheellng
and painless arthritic changes of the hands and feet, were observed 1n
50-70% of the patients examined. Since the signs and symptoms 20-25 years
later represented a continuum of signs and symptoms observed personally by
Peters and Gocmen (1959-1963), H was concluded that the symptoms repre-
sented the effects of both hexachlorobenzene toxldty and changes caused by
the Induced mixed porphyrla. Control patients from the villages Inhabited
by these patients Included unaffected family members and clearly demon-
strated clearly the uniqueness of this disorder which allowed for ready
Identification of affected patients. In addition the 60% Incidence of large
thyroid tumors 1n the females proved a sharp contrast to the 5% Incidence of
thyroid tumors 1n the geographical area. No conclusions were drawn as to
1835A 12-35 03/30/84
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TABLE 12-11
Clinical Signs and Symptoms 1n Humans 25 Years After Exposure to
Low Levels 1n HCB 1n Turkey, 1955-19593
Clinical Signs/Symptoms
No. of Patients
with Symptoms'3
Percent
Porphyrl a --Neurological
Weakness
Parestheslas
Sensory shading
Nervousness
Myotonla
"Cogwheellng"
Colic
Constipation
Recent red urine
Enlarged liver
Dermatologlc
Hyper pigmentation
Scarring
H1rsut1sm
Pinched fades
Fragile skin
Thyroid enlargement
Total
Men
Women
Orthopedic and others
Arthritis
Small hands
Short stature
117 (161)
89 (161)
75 (125)
39 (60)
35 (76)
34 (125)
84 (161)
31 (161)
17 (161)
10 (161)
125 (161)
134 (161)
81 (161)
69 (161)
62 (161)
64 (161)
26 (98)
38 (63)
108 (161)
107 (161)
74 (161)
73
55
60
65
46
27
52
19
IT
1
6
78
83
50
43
39
40
27
60
67
67
46
aSource: Peters et al., 1982
bNumbers 1n parentheses represent total number of patients examined for
this symptom
HCB = Hexachlorobenzene
1835A
12-36
03/23/84
-------
the Incidence of cancer and mortality. Studies on these endpolnts are still
1n progress and the length of time that has elapsed from the time of expo-
sure may not yet be adequate for drawing conclusions.
A boy and three women treated 1n the early 1960's with 1.v. and/or oral
edetlc add (the metal chelatlng agent EDTA) showed no active symptoms when
examined, and skin pigmentation and scarring were much less severe than 1n
most of the other patients. Urine and/or stool porphyrln studies showed
that seven patients had clearly recognizable Increases 1n porphyrln levels
(Table 12-12). Clinical chemistry and milk residue data are summarized 1n
Table 12-13. Percent i-am1nolevul1n1c add values were found to be above
the upper normal limit of 4 mg/8, 1n 32 of 55 patients. The average
residue levels 1n human milk samples from Turkish mothers with porphyMa was
0.5H0.75 ppm; 0.16^0.23 ppm was found 1n milk samples from nonporphyrlc but
hexachlorobenzene-exposed mothers.
12.2.3. Summary. A few ep1dem1olog1c studies with occupationally-exposed
workers have been reported, together with studies and surveys conducted 1n
Turkey and 1n the United States (I.e., Loulsana), on the general population
following accidental exposure to hexachlorobenzene. These studies qualita-
tively support the toxldty of hexachlorobenzene but give little dose
response Information. Biological monitoring of plasma levels show clearly
more hexachlorobenzene 1n plasma of exposed compared to non-exposed Individ-
uals although no biologically significant adverse health effects were seen
during the observation periods.
The exposure of humans to hexachlorobenzene 1n Turkey from 1955-1959
caused an epidemic of hexachlorobenzene Induced PCT, also known as porphrya
turdca, which 1s manifested by disturbed porphyrln metabolism, cutaneous
1835A 12-37 03/30/84
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CD
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TABLE 12-12
PorphyMn Levels 1n Patients and Controls*
Controls
Turkey,
mean + SO
(N=33)
United States,
mean + SO
(N=40)
Hexachlorobenzene-Exposed Patients
Patients with active porphyrla
(N.15)
Remainder
(N=146)
Stool («q/Q dry weight
Coproporphyrln Protoporphyrln Uroporphyrln
4.80 * 3.2 7.65 i 9.83 1.41 ± 1.57
6.1 i 4.7 21.1 i 11.6 2.8 + 2.7
70.14 12.19 25.8
(1.0-837.6) (0.7-61.8) (0.7-189.2)
5.74 9.02 1.19
(0.5-4.1) (0-103.4) (0-12.6)
Urine
Coproporphyrln
30.0 + 23.6
69.0 ± 27.0
174.5
(32.6-779.3)
31.91
(0-198.4)
(ug/l)
Uroporphyrln
5.80 i 4.25
9.0 ± 4.0
111.4
(16-1607)
7.25
(0-29.5)
*Source: Peters et al., 1982
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00
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TABLE 12-13
Laboratory Test Results of Turkish Patients3
Test
Urine
a-Am1nolevu!1n1c add, mg/t
PorphobHlnogen, mg/l
Copper, ppm
Z1nc, ppm
Serum
Copper, v9/dH
Z1nc, ug/dl
Creatlne klnase, units/1
Iron, vg/dst
Thyroid function tests
Thyroxlne, pg/dl
Tr11odothyron1ne uptake,
percent
Free thyroxlne Index
Blood
Lead, erythrocyte, yg/di,
Uroporphyrlnogen synthetasec
M1lk hexachlorobenzene, ppmd
Patients with porphyrla
Patients without porphyrla
Normal Range
<4
<1
0.01-0.06
0.1-0.7
70-155
70-120
women, <120
men, <150
65-170
5-11
37-59
1.85-6.5
<35
>20
NA
NA
Patient Range
0.14-10.1
0.11-1.04
0.01-0.046
0.02-1.22
88-153
57-112
65-141
51-318
69-147
2.2-10.1
36-51.1
0.9-4.6
2-17
12.4-34.8
0.51 (0-3.12)
0.16 (0-1.26)
No. of
Abnormal
Resultsb
32 (55)
0 (56)
0 (31)
7 (31)
0 (30)
9 (29)
1 (8)
4 (11)
0 (29)
women, 5 (10)
men, 2 (9)
women, 1 (10)
men, 1 (9)
women, 4 (10)
men, 0 (9)
0 (11)
5 (30)
53 (56)
16 (77)
aSource: Peters, et al.t 1982
bNumbers 1n parentheses represent total number of patient specimens
analyzed.
cValues expressed 1n nanomoles formed per mllllHter of RBCs per hour
Allowable limit 1n United States for cow's milk 1s 0.02 ppm
NA = Not applicable
1835A
12-39
03/23/84
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lesions and hyperplgmentatlon. The authors estimated that 0.05-0.2 g/day
were Ingested. In children under 1 year of age, pink sore was observed as
well as 95% mortality 1n these Infants.
Follow-up studies conducted with patients 20-25 years after the onset of
porphyrla showed that a few patients still had active porphyrla, whereas
>50% exhibited hyperplgmentatlon scarring as well as other dermatologlc,
neurologic and skeletal features of hexachlorobenzene toxldty. Hexachloro-
benzene residues were also found 1n the blood, fat or breast milk of some
patients.
A correlation was found between hexachlorobenzene levels 1n blood and
the number of years worked 1n a chlorinated solvents plant. The concentra-
tion of urinary uroporphyrlns and coproporphyrlns In workers ranged from
21-37 and 67-101 yg/l, respectively, for the period between 1974 and
1977. An ep1dem1olog1c survey conducted with 86 residents 1n the vicinity
of this chlorinated solvents plant showed elevated hexachlorobenzene
residues 1n plasma. Higher levels of hexachlorobenzene residues were found
in males than 1n females, but these were not associated with race or food
consumption.
12.3. MAMMALIAN TOXICOLOGY
12.3.1. Acute Toxldty. Information on the acute toxldty of hexachloro-
benzene was limited to oral LDcn values determined with a few mammalian
bu
species. The following LD™ values were reported 1n the available litera-
ture: rats, 3500-10,000 mg/kg; rabbits, 2600 mg/kg; cats, 1700 mg/kg; and
mice, 4000 mg/kg (IARC, 1979; NAS, 1977; Sax, 1979).
Graef et al. (1979) reported that hexachlorobenzene blocked the activity
of rat hepatic 3-hydroxystero1d dehydrogenase leading to the accumulation of
50-H-stero1ds, which are known Inducers of porphyMn biosynthesis. Hexa-
chlorobenzene-lnduced porphyrla has also been reported to occur as a result
1835A 12-40 03/30/84
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of a deficiency In the uroporphyrlnogen decarboxylatlon process that 1s
catalyzed by porphyrlnogen carboxylase. This enzyme Is the only one 1n the
heme pathway that exhibits a decrease 1n activity. The Inhibition of por-
phyrlnogen carboxylase 1n liver homogenates from female Wlstar rats with
severe porphyria Induced by hexachlorobenzene was studied by R1os de Molina
et al. (1980). Hexachlorobenzene had no effect on enzyme activity at
10"3 M, whereas pentachlorophenol caused a 90% Inhibition at the same con-
centration. However, pentachlorophenol did not Inhibit the enzyme at a con-
centration of 10~s M. It was concluded that a concentration >10~5 M of
pentachlorophenol, possibly together with other hexachlorobenzene metabo-
lites, was needed to cause enzyme Inhibition.
Hexachlorobenzene has also been reported to Induce the activity of
hepatic mlcrosomal enzymes 1n male or female rats following subchronlc
administration (Carlson, 1978; Carlson and Tardiff, 1976; Chadwlck et al.,
1977). Hexachlorobenzene produced a so-called "mixed-type" Induction of
cytochrome P-450 content 1n female rats resembling that produced by a com-
bination of phenobarbltal (cytochrome P-450) and 3,4-benzopyrene (cytochrome
P-448) (Goldstein et al., 1982; Debets et al., 1980a). In female rats,
hexachlorobenzene Increased the activities of (S-am1nolevul1n1c add syn-
thetase and amlnopyrlne demethylase (Ar1yosh1 et al., 1974), ethoxy-
resoruf1n-0-deethylase, amlnopyrlne demethylase, aryl hydrocarbon hydroxy-
lase, p-n1trophenol glucuronyl transferase, and NAOPH-cytochrome c reductase
(Goldstein et al., 1982; Debets et al., 1980a). Similarly, 1n male rats,
hexachlorobenzene Increased the activities of hepatic ethyl morphine N- and
p-n1troan1sol 0-demethylases, aniline hydroxylase, and UDP glucuronyl trans-
ferase (Mehendale et al., 1975), acetanlUde hydroxylase, acetanlllde ester-
ase, procalne esterase, and arylesterase activities (Carlson et al., 1979;
Carlson, 1980).
1835A 12-41 03/23/84
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12.3.2. Subchronlc Tox1c1ty. Several oral subchronlc studies of hexa-
chlorobenzene have been reported, but no studies were located on the effects
of hexachlorobenzene following Inhalation. In several animal species, hexa-
chlorobenzene was found to cause alopecia and scabbing, decreased body
weight, Increased liver and kidney weights and Increased porphyrln levels 1n
the urine and 1n several organs. H1stopatholog1c changes were noted 1n the
liver and kidneys of rats, gastric lymphold tissue of dogs, and ovaries of
monkeys. When placed on untreated diets, rats were able to recover from
most of the toxic effects of hexachlorobenzene treatment. Hexachlorobenzene
was also reported to cause certain neurologic effects (ataxla, paralysis,
etc.) on rats, mice, hamsters and female beagles, and to Induce an Increase
1n hepatic mlcrosomal enzyme activity. Toxldty data for hexachlorobenzene
can be found 1n Table 12-14.
latropoulos et al. (1976) reported that five adult female rhesus monkeys
given dally gavage treatments of hexachlorobenzene suspended 1n 1% carboxy-
methylcellulose at 8, 32, 64 or 128 mg/kg/day for 60 days, showed extensive
morphologic changes 1n the ovaries. These changes were dose-related.
Subchronlc studies conducted by Koss et al. (1980a) with groups of four
female rats treated orally (probably by gavage) with 100 mg/kg of hexachlo-
robenzene 1n olive oil every other day, suggested that hexachlorobenzene
metabolites covalently bind to cytosollc proteins although no binding to
uroporphyrlnogen decarboxylase was specifically demonstrated.
EUssalde and Clark (1979) reported a significant Increase 1n the In
vitro metabolism of 3H-testosterone by liver mlcrosomes from male mice fed
diets containing 250 mg hexachlorobenzene/kg for 21 days. In addition,
decreases 1n the concentration of testosterone 1n the serum and 1n the
1835A 12-42 03/30/84
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CO
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TABLE 12-14
Summary of Tox1c1ty Studies on Hexachlorobenzene
Species
Route
Dose
Duration
Effects
Reference
Rat
(females)
Rat
oral
oral
(diet)
100 mg/kg every other
day
0.5 mg/kg/day
2.0 mg/kg/day
8.0 mg/kg/day
32.0 mg/kg/day
up to 43 days
15 weeks exposed and
held to 48 weeks
15 weeks exposed and
held to 48 weeks
15 weeks exposed and
held to 48 weeks
15 weeks exposed and
held to 48 weeks
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Rat oral 50 mg/kg every other
(females) (gavage) day
Rats oral 0.5 mg/kg twice
(females) (gavage) weekly
2.0 mg/kg twice
weekly
8.0 mg/kg twice
weekly
32.0 mg/kg twice
weekly
Rat oral 100 mg/kg diet
(females) (diet)
15 weeks
29 weeks
29 weeks
29 weeks
29 weeks
98 days
CD
Suggested covalent binding of hexachlorobenzene Koss et al.,
metabolites to cytosollc proteins 1980a
Transient Increases 1n liver porphyrln levels Kulper-Goodman
1n females after termination of exposure et al., 1977
Increases 1n liver porphyrln levels 1n females
after termination of exposure, Increased size
of centrllobular hepatocytes
Increased liver weights. Increased liver,
kidney and spleen porphyrln levels In females
(porphyrla), centrllobular liver lesions espe-
cially 1n females at 48 weeks
Increased mortality 1n females, Intension
tremors 1n males and females and ataxla 1n a
few females. Increased liver, kidney and
spleen weights, Increased liver, kidney and
spleen porphyrln levels 1n females (porphyrla),
centrllobular liver lesions and splenomegaly
Increased liver, kidney, spleen and adrenal Koss et al.,
weights, porphyrla (Increased liver porphyrln 1978b
levels and Increased excretion of porphyrlns
and precursors), tremors, hair loss and skin
lesions
Increase 1n relative liver weight Boger et al.,
1979
Increase 1n relative liver weight, moderately
enlarged hepatocytes
Porphyrla, markedly enlarged hepatocytes,
Increase 1n relative liver weight
Porphyrla, markedly enlarged hepatocytes,
Increase 1n Hver weights
Porphyrla (Increased liver lobe porphyrlns). Smith et al.,
decreased activity of uroporphyrlnogen 1980
decarboxylase
-------
TABLE 12-14 (cont.)
00
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en
Species
Route
Dose
Duration
Effects
Reference
Rat
oral
{diet and
nursing)
Rat
IV)
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Rat
Rat
(male)
Rat
(female)
Rat
(female)
Rat
Rat
(females)
Rat
(females]
Rat
oral
(diet)
oral
(diet)
oral
(diet)
oral
(diet)
oral
(gavage)
oral
{gavage)
oral
(gavage)
oral
(diet)
oral
(diet)
50 mg/kg diet
150 mg/kg diet
500. 1000 or 2000
mg/kg diet
2000 mg/kg diet
2000 mg/kg diet
3000 mg/kg diet
50, 100 or 200 mg/kg
14 mg/kg every other
day
100 mg/kg every
other day
6-8 mg/kg/day
75 mg/kg diet
(4-5 mg/kg/day)
150 mg/kg diet
(8-9.5 mg/kg/day)
gestation until
5 weeks of age
gestation until
5 weeks of age
3 weeks
10 weeks
100 days
11 weeks
120 days
103 days
6 weeks exposed and
held for additional
18 months
75-90 weeks
up to 2 years
Depressed resistance to L. monocytoqenes and
T. sp1ral1s. enhanced thymus-dependent antibody
response
Increased serum IgM and IgG, depressed resis-
tance to L_. monocytoqenes and T. splralls.
enhanced thymus-dependent antibody response,
Increased liver and adrenal weights
Dose-related Increases 1n relative spleen,
lymph nodes, liver, adrenals, thyroid, testes
and kidney weights, dose-related Increase 1n
serum IgM levels, no change 1n serum IgG
levels, dose-related pathological changes In
liver, lymph nodes and spleen
Porphyria found microscopically at 5 weeks and
grossly at 10 weeks using fluorescence
Elevated hepatic enzymes by 1 week and Increased
urinary porphyrln and ALA levels (porphyria) as
early as 40 days
Decreased uroporphyrImogen decarboxylase
activity and porphyria after 4 weeks
Dose- and time-dependent Increase 1n liver and
urine porphyrlns (porphyria)
Porphyria 1n treated females, susceptibility of
females to porphyria may be related to estrogen
levels
Porphyria (liver uroporphyrln levels peaked 7
months postexposure and levels had not returned
to normal by 18 months), decreased liver proto-
porphyMn and coproporphyMn levels, Inhibition
of uroporphyrlnogen decarboxylase activity
until 18 months postexposure
Decline 1n body weights, porphyria, enlarged
livers and liver tumors
Porphyria, time-related appearance of severe
hepatic and renal pathologies, after 1 year In-
creases In hepatomas, hepatocarclnomas, bile duct
adenomas, renal adenomas and renal carcinomas
Vos et al.,
1979b
Vos et al.,
1979a
Gralla et al.,
1977
Llssner
et al., 1975
Elder et al.,
1976
Carlson, 1977b
R1zzard1n1 and
Smith, 1982
Koss et al.,
1983
Smith and
Cabral, 1980
Lambrecht et
al., 1983a,b
-------
TABLE 12-14 (cont.)
co Species
CO
' H
3>
Rat
Rat
Route
oral
(diet)
oral
(diet and
nursing)
oral
(diet)
Dose
0.32. 1.6, 8.0 or
40 mg/kg diet
0.32 or 1.6 mg/kg
diet
8.0 mg/kg diet
40 mg/kg diet
10 or 20 mg/kg diet
Duration
-130 days
gestation through
lifetime (130 weeks)
gestation through
lifetime (130 weeks)
gestation through
lifetime (130 weeks)
FQ to F4 generations
Effects Reference
HematologUal changes at all dose levels 1n Arnold et al.,
males, Increases In liver and heart weights 1n 1983
males at 8.0 and 40 ppm diets, no treatment-
related effects observed In bred females
Glycogen depletion In 1.6 mg/kg males; no
effects reported at 0.32 mg/kg
Increase 1n liver pathologies
Increased mortality as pups, Increase 1n liver
and kidney pathologies, Increase In adrenal
pheochromocytomas In females and parathyroid
tumors In males
No effects reported Grant et al.,
1977
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Rat
Rat
Rat
oral
(diet)
oral
(diet)
oral
(diet)
40 mg/kg diet
80 mg/kg diet
160 mg/kg diet
320 and 640 mg/kg
diet
60, 80. 100. 120 or
140 mg/kg diet
0 or 80 mg/kg diet
80 mg/kg diet
Frj to F$ generations
FQ to F4 generations
FO to F$ generations
FQ to F^ generations
FQ to F-|a and
generations
gestation and
nursing or cross
nursed with controls
2 weeks prior to
mating to 35-36 days
after weaning
Increases In liver weights and aniline
hydroxylase activity
Decreased body weights, f% and f$ generations had
decreased lactation Index and postnatal viability
and Increased stillbirths
Increased mortality and decreased lactation
Index starting 1n F-| generation
20 and 50% mortality 1n FQ 320 and 640 mg/kg
groups, respectively, greatly reduced fertility
Index and Utter size and Increase 1n still-
births, viability Index zero 1n F^
Increased mortality In all groups at 21 days,
21 -day LDso values for pups were 100 and 140
mg/kg for F]a and FI^ generations, respectively
Nursing exposure produced greater effects than
did gestatlonal exposure, effects noted were:
smaller brains, hearts, kidneys and spleens,
Increased liver weights
Increased porphyrln levels and decreased liver
esterase activity In dams, no changes In
gestation Indices or neonatal survival
Kltchln
et al.. 1982
Mendoza
et al., 1978
Mendoza
et al., 1979
-------
TABLE 12-14 (cont.)
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U-l
Species
Rat
Route
oral
(gavage)
Dose
10, 20, 40. 60, 80
or 120 mg/kg
Duration
days 6-21 of gesta-
tion
Effects
Maternal toxldty (weight loss, tremors and
convulsions) and reduced fetal weights at 120
Reference
Khera, 1974
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-P.
and 80 mg/kg maternal doses, dose-related In-
crease 1n Incidence of unilateral and bilateral
14th Mb, sternal defects were also noted 1n
one experiment
House
House
(male)
Mouse
(male)
Mouse
Mouse
Hamster
Hamster
Cats
(breeding
females)
oral
(diet)
oral
(diet)
oral
(diet)
oral
(diet)
oral
(gavage)
oral
(diet)
oral
(diet)
oral
(diet)
2.5, 25 or 250
mg/kg diet
10 mg/kg diet (8.4
(mg/mouse/24 weeks)
or 50 mg/kg diet
(35.3 mg/mouse/
24 weeks)
167 mg/kg diet
6, 12, 24 and 36*
mg/kg/day
100 mg/kg/day to
pregnant mice
200 or 400 mg/kg
diet
4, 8 or 16 mg/kg/day
3 or 8.7 mg/day/cat
21 days
24 weeks
3-6 weeks
101-120 weeks
*(15 weeks exposed
held until 120
weeks)
days 7-16 of
gestation
90 days
Hfespan
142 days
Dose-related Increase 1n liver and decrease 1n
prostate and seminal vesicle weights, dose-
related alterations In testosterone metabolism,
altered hepatic enzyme levels
Dose-related reduction 1n weight gain, no tumor
pathology observed
Impairment In host resistance as measured by
Increased sensitivity to S. typhosa and P.
bergherl. and decrease 1n IgA levels
Reduced growth rate at all dose levels, short-
ened llfespan associated with tremors and con-
vulsions In 24 and 36 mg/kg/day groups, dose-
dependent Increase 1n liver-cell tumors 1n the
12, 24 and 36 mg/kg/day dose groups
Increased maternal livers and decreased fetal
body weights, Increased Incidence of abnormal
fetuses per Utter observed
Predrrhotlc and clrrhotlc hepatic lesions,
bile-duct hyperplaslas and hepatomas
Shortened Hfespan In 16 mg/kg/day group, In-
crease In hepatomas at all dose levels, Increase
1n liver haemang1oendothel1oma In males and
females and an Increase 1n thyroid alveolar
adenomas In males 1n 16 mg/kg/day group
Weight loss and Increased disease susceptibility
In bred females, dose-related decrease 1n Utter
size and survival of offspring, hepatomegaly 1n
offspring
EUssalde and
Clark, 1979
Sh1ra1 et al.,
1978
Loose et al. ,
1978a,b
Cabral et al. ,
1979
Courtney
et al., 1976
Lambrecht
et al.. 1982
Cabral et al. ,
1977
Hansen et al . ,
1979
-------
TABLE 12-14 (cont.)
r\j
i
Species
Minks
Dog
(female)
Dog
Monkey
(female)
Monkey
Route
oral
(diet)
oral
(capsule)
oral
(capsule)
oral
(gavage)
oral
(nursing)
Dose
1 or 5 mg/kg diet
50 or 150 mg/kg/day
1, 10, 100 or 1000
mg/day/dog
8. 32. 64 or 128
mg/kg/day
7.51-186 ppm milk
Duration
during gestation
until 17 weeks of
age
21 days
1 year
60 days
60 days
Effects
Dose-related Increase 1n offspring mortality,
Induction of nepatlc MFO enzymes 1n exposed
offspring
Liver and hepatocyte enlargement, dose-Induced
electroencephalogram dysrhythmlas
Increase 1n mortality, neutrophlUa, and
anorexia In the 100 and 1000 mg dose groups,
dose-related nodular hyperplasla of gastric
lymphold tissue 1n all treated animals
Dose-related pathology In liver, kidney, ovaries
and thymus
2 of 3 Infants died as a result of exposures
Reference
Rush et al. ,
1983
Sundlof
et al., 1981
Gralla et al. ,
1977
latropoulus
et al., 1976
Bailey et al. ,
1980
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00
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weights of seminal vesicles and ventral prostates were reported. Hexa-
chlorobenzene was also reported to cause certain neurologic lesions 1n male
and female rats, hamsters and mice fed diets containing varous levels of
hexachlorobenzene for 13 weeks. These Included hyperemla, edema, arboriza-
tion and hemorrhages 1n the brain and menlnges. The lesions extended to the
cerebrum, cerebellum, medulla, spinal cord and their menlnges. The severity
of these lesions was higher 1n males and was dose dependent 1n both sexes
(Headley et al., 1981). Physiologic changes (electroencephalogram dys-
rhythmlas) 1n the central nervous system were reported 1n 10 female beagles
receiving gelatin capsules containing doses of 50 or 150 mg/kg of hexa-
chlorobenzene for 21 days (Sundlof et al., 1981).
Kulper-Goodman et al. (1977) conducted a 15-week subchronlc feeding
study wherein groups of 70 male and 70 female COBS rats were fed diets pro-
viding 0, 0.5, 2, 8 or 32 mg/kg bw/day of hexachlorobenzene dissolved 1n
corn oil (5%). Female rats were more susceptible to hexachlorobenzene than
males, as Indicated by all the parameters studied, and a NOEL of 0.5 mg/kg/
day was suggested by the authors. This NOEL may be better Interpreted as a
NOAEL since a transient Increase 1n liver porphyrln levels was observed 1n
females 4 weeks after removal from hexachlorobenzene. The 2 mg/kg/day dose
may be Interpreted as a LOAEL since this level caused Increases 1n liver
porphyrln levels 1n females even 33 weeks after removal from hexachloroben-
zene, and Increases 1n the relative observed severity of centrllobular liver
lesions as compared to control rats. About 40% mortality occurred In
females, but none 1n males at the highest dose. Clinical signs Included
Intention tremor, excessive Irritability, multiple alopecia, scabbing and
ataxla, with hind leg paralysis at the highest dose. There was a signifi-
cant Increase 1n liver and kidney weights at the higher doses. An Increase
1835A 12-48 03/30/84
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1n liver weight was also found 1n groups of 36 female Wlstar rats treated by
gavage twice weekly with hexachlorobenzene dissolved 1n olive oil at 32
mg/kg for 29 weeks (Boger et al., 1979). Similarly, Koss et al. (1978b)
reported a 1.5- to 2-fold Increase 1n the weights of the liver, spleen,
kidneys and adrenal glands from female Wlstar rats treated orally (esopha-
geal tube) with 50 mg/kg of hexachlorobenzene dissolved 1n corn oil every
other day for 15 weeks. When hexachlorobenzene-treated rats were placed on
untreated diets, they no longer showed signs of hexachlorobenzene toxlclty,
such as dermal lesions, and body and organ weights returned to normal
(Kulper-Goodman et al., 1977; Koss et al., 1978b). Enlarged livers were
reported 1n subchronlc studies with female beagles (Sundlof et al., 1981)
and male mice (Sh1ra1 et al., 1978) administered hexachlorobenzene 1n diet.
A dose-dependent enlargement of hepatocytes was observed 1n groups of 36
female Wlstar rats receiving gavage treatments of olive oil containing hexa-
chlorobenzene (99.8% pure) 0.5, 2.0, 8.0 and 32 mg/kg twice weekly for 29
weeks (Boger et al., 1979). This effect was associated with the prolifera-
tion of the smooth endoplasmlc retlculum 1n the centrllobular area, and an
Increase 1n glycogen deposits; however, animals receiving 0.5 mg/kg did not
develop enlarged hepatocytes. In addition, atypical membrane complexes 1n
treated animals were noted and liver-cell mitochondria were moderately
enlarged and had Irregular shapes. An Increase 1n the size of centrllobular
hepatocytes was also reported 1n male and female rats receiving 2 mg/kg/day
for 15 weeks, together with hlstopathologlc changes In the spleen (Kulper-
Goodman et al., 1977).
Nodular hyperplasla of gastric lymphold tissue was reported In groups of
6 male and 6 female beagles receiving dally gelatine capsules containing 1,
10, 100 and 1000 mg hexachlorobenzene/dog/day for 12 months (Gralla et al.,
1835A 12-49 03/23/84
-------
1977). Extensive dose-related hlstopathologlc changes were also observed 1n
ovaries from groups of two rhesus monkeys given dally methyl cellulose/
distilled water solutions containing doses of 8, 16, 32, 64 or 128 mg hexa-
chlorobenzene/kg of body weight by gavage for 60 days (Knauf and Hobson,
1979; latropoulas et al., 1976). Sh1ra1 et al. (1978) conducted a 24-week
study with male mice fed diets containing 10 or 50 ppm of hexachlorobenzene,
followed by a recovery period of 14 weeks. Hlstologlc examination revealed
no pathologic changes 1n the liver or any other organ.
Lambrecht et al. (1982) fed male and female Syrian golden hamsters hexa-
chlorobenzene at doses of 0, 200 and 400 ppm 1n their diet for 90 days. The
hamsters were killed on day 91 and at 6-week Intervals through day 361. No
differences were seen 1n growth and food consumption between control and
exposed animals. The liver was reported as the most severely affected organ
exhibiting a variety of preclrrhotlc and drrhotlc lesions, bile-duct hyper-
plaslas and hepatomas. The Incidence of neoplasms found 1n this study will
be further discussed 1n Section 12.3.5.
Hexachlorobenzene has been found to cause Increased porphyrln levels 1n
the liver of male and female rats receiving the compound Incorporated Into
the diet at doses of 8 and 32 mg/kg/day for 15 weeks (Kulper-Goodman et al.,
1977). Koss et al. (1978b) reported that female rats treated orally with 50
mg nexachlorobenzene/kg every other day for 15 weeks still showed Increased
levels of porphyrln 1n the liver, 38 weeks after the last treatment. In
addition, porphyrln, 6-am1nolevul1n1c add, and porphobHlnogen levels 1n
the urine gradually Increased during the 15-week treatment period, but sub-
sequently decreased to normal levels. Smith et al. (1980) reported that the
lobes of livers from female Agus rats fed diets containing 0.01% hexachloro-
benzene developed porphyrla at different rates. During the Initial course
1835A 12-50 03/23/84
-------
of treatment, porphyMa 1n the caudate lobe developed at a significantly
slower rate than the median, left or right sections of the liver, but event-
ually, all lobes became equally porphyMc. In contrast, porphyMa was not
observed when viewed for hepatic fluorescence of porphyrlns in male and
female beagle dogs treated dally with 0, 1, 10, 100 or 1000 mg/dog/day for 1
year (Gralla et al., 1977). Gralla et al. (1977) observed that female CO
rats fed 0.2% hexachlorobenzene were porphyrlc using this fluorescence
method.
R1zzard1n1 and Smith (1982) clearly confirmed that female rats are more
susceptible to hexachlorobenzene-lnduced porphyrla than are male rats, and
that this difference 1n susceptibility 1s probably associated with the
faster metabolism of hexachlorobenzene 1n females. They Intubated male and
female F344/N rats every other day for 103 days with 14 mg/kg (50 vimole/
kg) hexachlorobenzene dissolved 1n arachls oil and monitored the rats for
hexachlorobenzene metabolites and porphyrln levels. The results indicated
that after 75 days of hexachlorobenzene treatment the excretion of urinary
porphyrlns increased rapidly 1n the females and after 103 days the females
had urine and liver porphyrln levels 40- and 310-fold higher, respectively,
than did the males. During this treatment period the females were found to
excrete greater quantities of hexachlorobenzene metabolites, especially
pentachlorothlophenol, than the males. Estrogen levels seem to play an
important part 1n the Increased susceptibility of females to hexachloroben-
zene-lnduced porphyria. When both male and female rats were pretreated
intraperltoneally with four doses of 20 pmole/kg of dlethylstlIboestrol
dipropionate (an estrogenic drug), both sexes had stimulated excretion of
hexachlorobenzene metabolites.
1835A 12-51 03/30/84
-------
A better understanding of hexachlorobenzene-lnduced porphyrla was
provided by Koss et al. (1983). These researchers administered every other
day for 6 weeks, through stomach tube, TOO mg/kg hexachlorobenzene dissolved
1n olive oil to female Wlstar rats and then observed the rats for an addi-
tional 18 months. The rats were evaluated during both the exposure period
and the 18-month holding period for liver hexachlorobenzene levels, levels
of liver porphyrlns, and the activity of liver uroporphyMnogen decarb-
oxylase. The results revealed a rapid Increase 1n hexachlorobenzene liver
levels which reached a plateau after 10 days of treatment and remained
constant until exposure was terminated at 6 weeks. The levels of liver
hexachlorobenzene then decreased over time with no valid biological halfUfe
determlnable. The liver porphyMn levels, however, started to rise slightly
after 3 weeks of hexachlorobenzene exposure and reached a maximum Hver
porphyMn concentration ~7 months after the exposures had ceased (Table
12-15). The liver porphyrln levels decreased to a constant level -14 months
after ceasing hexachlorobenzene exposures. At 18 months after ceasing
exposures, the treated rats liver porphyrln levels were still substantially
higher than the levels 1n control rats. The distribution pattern of the
liver porphyrlns was observed to be changed as early as after the second
hexachlorobenzene administration. The observed changes were Increases 1n
liver uroporphyrln levels and decreases 1n liver protoporphyMn and
coproporphyrln levels. The change 1n porphyrln patterns was traced to the
decreased activity of uroporphyMnogen decarboxylase activity which was
found to be not detectable at the end of the 6-week exposure period and the
activity did not become detectable again until 18 months postexposure
1835A 12-52 03/30/84
-------
TABLE 12-15
Porphyrln Content and Uroporphyrlnogen Decarboxylase Activity
1n the Liver Cytosol of Female Rats Pretreated with 100 mg/kg HCB
Every Other Day for 6 Weeks3
Time After the
End of Treatment
1 day
7 months
14 months
18 months
Controls
Porphyrln Content
(nmol/6 ml cytosol )b
14
133
9
8
0.06
±3d
t 15
± &
± 5
+ 0.04
Enzyme Activity
(pmol • mg"1 • mln"1)1-
NDe
NO
ND
0.3 + 0.2d
0.5 + 0.1
aSource: Koss et al., 1983
b6 ml cytosol correspond with 1 g liver tissue
cpmol coproporphyrlnogen I (determined as coproporphyrln) formed from uro-
porphyrlnogen I 1n 1 m1n by 1 mg cytosol protein
dMean (± SD) of three or four animals
eND - Not_ detectable. The lower detection limit was determined at 0.02
pmol • mg"1 • mln"1 coproporphyrln
HCB = Hexachlorobenzene
1835A 12-53 03/23/84
-------
(see Table 12-15). These data led the Investigators (Koss et al., 1983) to
propose that there are four phases of hexachlorobenzene-lnduced porphyMa:
During the first phase an almost constant content of hexa-
chlorobenzene and a gradual decrease of uroporphyrlnogen decarboxy-
lase activity 1s achieved. In the second phase a noticeable accu-
mulation of porphyrlns and a practically complete Inhibition of
decarboxylase activity are conspicuous. In the third phase, which
occurs after hexachlorobenzene administration has been discon-
tinued, a further accumulation of porphyrlns and a continuing Inhi-
bition of uroporphyrlnogen decarboxylase activity can be seen, even
after extensive elimination of hexachlorobenzene. During the
fourth phase a decrease 1n porphyrln content and a return of
decarboxylase activity are clearly observable.
A possible reason for the continued Inhibition of uroporphyrlnogen decarb-
oxylase activity, even after substantial elimination of hexachlorobenzene
has occurred, was also discussed 1n this report. Koss et al. (1983) pre-
sented the scenario that once hexachlorobenzene had caused an Inhibition of
uroporphyrlnogen decarboxylase activity and Increased liver porphyrln levels
that the accumulation of porphyrlns could themselves maintain the Inhibition
of the enzyme activity.
Hexachlorobenzene pretreatment has been reported to cause altered Immune
responses. Vos et al. (1979b) studied the effect of hexachlorobenzene on
the Immune system after combined pre- and postnatal exposure. Wlstar rats
were fed diets containing 50 or 150 yg/kg hexachlorobenzene during preg-
nancy and lactation. The pups were weaned after 3 weeks and continued on
the test diets until 5 weeks of age, when their Immune system was function-
ally assessed. At the higher dietary level, hexachlorobenzene caused a
statistically slgnflcant Increase 1n serum IgM and IgG concentrations.
Hexachlorobenzene treatment also caused a decreased resistance to Infec-
tion with Listerta monocytogenes (Vos et al., 1979b). The LD5Q values
were reported to be 14xlOs, 7.1xl05 and S.OxlO5 bacteria 1n pregnant
Wlstar rats receiving diets containing 0, 50 and 150 mg/kg, respectively.
1835A 12-54 03/23/84
-------
Similarly, decreased resistance of Tr1ch1nella splralls Infection, as Indi-
cated by an Increase 1n the number of larvae found 1n muscle tissue, was
noted. Hexachlorobenzene also enhanced the thymus-dependent antibody
response to J_^ splralls antigen and to tetanus toxold. No effects were
observed on allograft rejection, mltogenlc response of thymus and spleen
cells, thymus-lndependent IgM response to EscheMchla coll llpopolysac-
chaMde, passive cutaneous anaphylaxls, and on the clearance of carbon par-
ticles and L_._ monocytogenes. The authors concluded that hexachlorobenzene
suppressed cellular Immunity and enhanced humoral Immunity 1n both test
groups.
In contrast, hexachlorobenzene pretreatment of weanling rats did not
alter their cell-mediated Immunity, but did stimulate their humoral Immune
response and enhanced the 1_n vitro responsiveness of spleen cells to dif-
ferent mltogens, which was mainly a result of an Increase 1n the number of
splenic lymphocytes. The rats received diets containing 1000 pg hexa-
chlorobenzene/g for 3 weeks after weaning, before assessing their Immune
system (Vos et al., 1979a).
Loose et al. (1978a,b) found that hexachlorobenzene pretreatment also
resulted 1n Impaired host resistance. Male BALB/c mice received diets con-
taining 167 yg hexachlorobenzene/g for 3 or 6 weeks before assessing their
Immune functions. The concentration of IgA was significantly decreased,
whereas those of IgG and IgM did not exhibit consistent significant altera-
tions as compared with the controls. Hexachlorobenzene-treated mice were
more sensitive to gram-negative endotoxln (Salmonella typhosa), showed a
decreased resistance to a malaria challenge (Plasmodlum berghel), and
exhibited slgnflcantly depressed antibody synthesis.
1835A 12-55 03/23/84
-------
12.3.3. Chronic Tox1c1ty. Cabral et al. (1977) studied the tumor1gen1c1ty
of hexachlorobenzene 1n 6-week-old Syrian golden hamsters given 0, 50 (4
mg/kg/day), 100 {8 mg/kg/day) and 200 (16 mg/kg/day) ppm hexachlorobenzene
1n their diets for their remaining Hfespan. Shortened Hfespan was
observed 1n the male and female 200 ppm dose groups after 70 weeks of expo-
sure along with marked weight reduction 1n the males. Neoplasms were
Increased by the hexachlorobenzene exposures and are reported in Section
12.3.5. No other pathologies were reported 1n this study.
Cabral et al. (1979) studied the tumor1gen1c1ty of 6- to 7-week-old male
and female outbred Swiss mice given 0, 50 (6 mg/kg/day) 100 (12 mg/kg/day)
and 200 (24 mg/kg/day) ppm hexachlorobenzene for 101-120 weeks and 300 ppm
(36 mg/kg/day) hexachlorobenzene for 15 weeks and held until 120 weeks of
age. Results Indicated that shortened Hfespan occurred 1n the 200 and 300
ppm dose groups starting after the 30th week of the test and that this
reduced survival was associated with tremors and convulsions. Reduction 1n
the rate of growth was observed 1n female mice 1n the 50, 200 and 300 ppm
dose groups and more pronounced growth rate reduction was observed 1n male
mice 1n the 100, 200 and 300 ppm dose groups. An Increase 1n neoplasms were
found as a result of hexachlorobenzene exposures and are discussed 1n
Section 12.3.5. No other pathologies were reported 1n this study.
Smith and Cabral (1980) fed young female Agus or MRC Wlstar rats 100 ppm
(6-8 mg/kg/day) hexachlorobenzene 1n a diet containing 2% arachis oil for 90
weeks. Hexachlorobenzene exposure resulted 1n a steady decline 1n body
weights over the study period and 1n the exposed rats possessing less hair
than the controls. Tremors or other nervous symptoms were not seen during
this study. Onset of porphyrla was observed 1n the hexachlorobenzene rats
after ~3 months, as Indicated by urines fluoresdng red under UV light, and
1835A 12-56 03/23/84
-------
liver porphyrla was confirmed at autopsy by a red fluorescence of the liver.
The livers were enlarged 2-fold 1n the hexachlorobenzene-exposed females and
were associated with multiple liver cell tumors. This neoplastlc Incidence
will be discussed 1n Section 12.3.5.
Male and female Sprague-Dawley rats were fed hexachlorobenzene diets for
2 years containing 0, 75 or 150 ppm hexachlorobenzene (Lambrecht et al.,
1983a,b). Four rats per group were killed at weeks 0, 1, 2, 3, 4, 8, 16,
32, 48 and 64 of the study and liver and kidney evaluations were made.
Times of appearance of lesions were as follows: 4 weeks — hepatic hyper-
emla, edema, parenchymal and hydropic degeneration, renal hyperemla, con-
gestion, swelling and parenchymal degenerations; 32 weeks -- renal tubular
nephritis with hyaline casts, severe parenchymal degeneration, epithelial
necrosis accompanied by proximal convoluted tubular regeneration, and pre~
neoplastlc foci; and 36 weeks -- hepatic preneoplastlc fod; and 64 weeks --
hepatic neoplasms and renal neoplasms. The Incidence of neoplasms will be
further discussed In Section 12.3.5.
A two-generation hexachlorobenzene (analytical grade) feeding study was
conducted using Sprague-Dawley rats fed diets containing 0 (64 males, 64
females), 0.32 (40 males, 40 females), 1.6 (40 males, 40 females), 8.0 (40
males, 40 females), or 40.0 (66 males, 66 females) ppm hexachlorobenzene
(Arnold et al., 1983). The parental rats (F ) received their respective
test diets for 90 days before mating and until 21 days after parturition (at
weaning), at which time they were killed and evaluated for hexachloro-
benzene-lnduced effects. The number of offspring (F generation) from
these matlngs were reduced to 50 males and 50 females per dose group at 28
days of age and fed their respective parents' diets. Thus, the F, animals
1835A 12-57 03/30/84
-------
were exposed to hexachlorobenzene and metabolites In utero, from maternal
nursing and from their diets for the remainder of their lifetime (130 weeks).
The results from this two-generation study Indicated no consistent
treatment-related effects upon growth or food consumption 1n either gener-
ation and no change 1n fertility, gestation or lactation Indices. A
decreased viability Index was noted In the 40.0 ppm group relative to con-
trols. No treatment-related effects were found 1n the FQ females. The
Fn males were found to have significantly Increased liver, heart and brain
weights 1n the 8.0 ppm group and significantly Increased liver and heart
weights 1n the 40.0 ppm group. The F males were observed to have various
significant changes 1n hematologlcal parameters at all dose levels. Neo-
plasms were seen 1n the F generation and are discussed 1n Section 12.3.5.
The F, generation had dose-related significant Increases 1n: 1) centM-
lobular basophlllc chromogenesls reported as slight 1n the 8.0 and 40.0 ppm
male and female dose groups and as moderate 1n the 40.0 ppm male and female
dose groups; 2) per1bH1ary lymphocytosls and flbrosls 1n the 40.0 ppm male
group; and 3) severe chronic nephrosls 1n the 40.0 ppm male dose group.
In a second study conducted by Arnold et al. (1983), 50 male Sprague-
Dawley rats per group were fed hexachlorobenzene (0 or 40 ppm) and various
levels of vitamin A diet (0.1, 1 or 10 times normal control levels). The
test groups were as follows: control diet; control diet plus 40 ppm hexa-
chlorobenzene; 1/10 vitamin A diet; 1/10 vitamin A diet plus 40 ppm hexa-
chlorobenzene, 10 times control vitamin A diet; and 10 times vitamin A diet
plus 40 ppm hexachlorobenzene. Five rats per group were killed and evalu-
ated both at 25 and 49 weeks and the remaining animals were killed and
evaluated after 119 weeks.
1835A 12-58 03/30/84
-------
Results revealed that the animals on the 1/10 vitamin A diet had sig-
nificantly reduced body weights and surv1vab1l1ty when compared with control
diet animals. The animals on 1/10 vitamin A plus 40 ppm hexachlorobenzene
diet had significantly decreased body weights and did not survive as long as
rats receiving the control diet plus 40 ppm hexachlorobenzene. Hematolog-
1cal evaluations revealed no consistent treatment-related effects. Neo-
plasms were observed 1n the test animals and are discussed 1n Section
12.3.5. No significant differences were found 1n the Incidence of any
pathological lesions between the test groups.
12.3.4. Mutagen1c1ty. In a dominant lethal mutation study, male rats
(strain not given) received by gavage 0, 70 or 221 mg hexachlorobenzene/kg
body weight orally for 5 consecutive days. A dose-dependent reduction 1n
male reproductive performance was observed, but hexachlorobenzene did not
Induce dominant lethal mutations {Simon et al., 1979). Khera (1974) also
reported a lack of dominant lethal mutations 1n Wlstar rats following oral
administration of 0, 20, 40 or 60 mg hexachlorobenzene/kg for 10 consecutive
days. In 14 sequential mating trials, no significant differences 1n the
Incidence of pregnancies, corpora lutea, live Implants and dedduomas
between the treated and control groups were observed. Mutagenlc activity
has been observed 1n a yeast, Saccharomyces cerevlslae. assay (Guerzonl et
al., 1976). The mutagenlcHy of hexachlorobenzene was Investigated 1n three
strains of S_._ cerevlslae using reversion from h1st1d1ne and methlonlne auxo-
trophy, and hexachlorobenzene was reported to be mutagenlc at a minimum con-
centration of 100 ppm.
Lawlor et al. (1979) measured the activity of hexachlorobenzene 1n the
Ames assay, strains TA98, TA100, TA1535, TA1537 and TA1538, at five unspeci-
fied dose levels both with and without metabolic acH1vat1on by Aroclor 1254
1835A 12-59 03/30/84
-------
Induced rat liver mlcrosomes. Hexachlorobenzene possessed no detectable
levels of mutagenlc activity 1n any of the Salmonella strains used either
with or without mlcrosomal activation. These results were reported 1n an
abstract with few experimental details. In addition, this result 1s not
unexpected because the Salmonella test system 1s generally Insensitive to
chlorinated compounds.
12.3.5. Carc1nogen1c1ty. Studies on the carcinogenic potential of hexa-
chlorobenzene have been carried out on hamsters, mice and rats.
12.3.5.1 HAMSTER STUDIES —
12.3.5.1.1. Cabral et al. (1977) — In one study on Syrian golden
hamsters (Cabral et al., 1977) hexachlorobenzene was administered 1n the
diet at 50, 100 or 200 ppm. These concentrations correspond to dosages of
4, 8 and 16 mg/kg/day based on body weight and food Intake averages. The
hexachlorobenzene was prepared by dissolution In corn oil which was then
mixed with the feed. The feed was analyzed periodically to Insure that the
Intended level of hexachlorobenzene was maintained (Mollner, 1983). The
hexachlorobenzene preparation used 1n this study was 99.5% pure. Impurities
reported to be present 1n some hexachlorobenzene preparations Include
chlorinated dlbenzofuran and chlorinated d1benzo-p-d1ox1n, both members of
classes of compounds which are carcinogens (VUleneuve et al., 1974). The
dosages selected for this study were chosen 1n order to be comparable to
those believed to be consumed by victims of accidental hexachlorobenzene
1ngest1on in Turkey.
In this study on hamsters 1t was difficult to determine from the pub-
lished report whether an MTD was reached or exceeded because the Information
on mortality and weight changes was not detailed enough for unambiguous
evaluation. Although mortality was monitored, the Investigators only stated
1835A 12-60 03/23/84
-------
that 71% of the treated animals were alive at 50 weeks and that at the
highest dose, 16 mg/kg bw/day, there was a reduced Hfespan among treated
animals after 70 weeks. The study was run for the lifetime of the animals,
but the actual duration 1n weeks was not given. Since the Investigators
also reported "marked weight reduction" 1n the highest dose group one could
conclude that the MTD may have been reached. However, 1n the absence of
weight data definite conclusions cannot be made.
The tumor Incidence among the hamsters 1s given 1n Table 12-16. The
Incidence of hepatomas 1n males and females was statistically significant 1n
all treated groups. The Incidence of liver haemangloendothelloma 1n males
and females was statistically significant 1n the high dose groups and 1n
males 1n the middle dose groups. There was a significant dose-related trend
for both tumor types. Three Instances of metastases were found among the
animals with liver haemangloendothelloma. No hepatoma metastases were
found. One of the hepatomas 1n a female animal was found at necropsy at 18
weeks; the Investigators did not Indicate which dosage level this animal
received.
Hamsters 1n the control groups showed no thyroid tumors but thyroid
alveolar adenomas were significantly Increased 1n the high dose males and
there was a significant dose-related trend. In female thyroid tumors
occurred 1n all treated groups of females but were not statistically sig-
nificant.
Chemical Induction of thyroid tumors has not been Identified with chem-
ically related compounds except for toxaphene, which 1s a mixture of chlori-
nated camphene derivatives. Other chemicals associated with Induction of
thyroid tumors are thloureas, thlouradls, 3-am1no-4-ethoxyacetan1l1de,
amltrok, o-an1s1d1ne, 2,4-d1am1nan1sole sulfate, ethlonamlde, 4,4'-methylene
1835A 12-61 04/16/84
-------
00
CO
TABLE 12-16
Tumor Incidence 1n Hamsters Given HCB 1n the Diet*
ro
l
er-
r\j
Group
Control
SO ppm
(4 mg/kg)
100 ppm
(8 mg/kg)
200 ppm
{16 mg/kg)
Effective
No.
39 F
40 M
30 F
30 M
30 F
30 M
60 F
57 M
TBA
No.
5
3
16
18
18
27
52
56
No. of Tumors
X
12.8
7.5
53.3
60.0
60.0
90.0
86.6
98.2
No.
5
3
21
27
32
45
73
87
per
Hamster
0.13
0.08
0.70
0.90
1.06
1.50
1.21
1.52
Hore Than
One Tumor
No.
0
0
4
8
11
14
15
27
X
0
0
13.3
26.6
36.6
46.6
25.0
47.3
Thyroid
No.
0
0
2
0
1
1
3
8
X
0
0
6.6
0
3.3
3.3
5.0
14.0
Hepatoma
No.
0
0
14
14
17
26
51
49
X
0
0
46.6
46.6
56.6
86.6
85.0
85.9
Haemanq1oendothe11omas
Liver Spleen
No.
0
0
0
1
2
6
7
20
X
0
0
0
3.3
6.6
20.0
11.6
35.0
No.
1
0
0
1
3
3
4
4
X
2.5
0
0
3.3
10.0
10.0
6.6
7.0
Other
No.
4
3
5
11
9
9
8
6
X
10.2
7.5
16.6
36.6
30.0
30.0
13.3
10.5
*Source: Cabral et at.. 1977
TBA = Tumor-bearing animals
HCB = Hexachlorobenzene
o
CO
CO
\
CO
-------
b1s(n,n'-d1methyl) n,n'-d1methy"!benzenam1ne, 1,5-naphthylened1am1ne, 4,4'-
oxydlanaHne, pronetalol-HCl, 4,4'-th1od1anal1ne, lodoform, dlbromomethane
and dlchloroethane (Krayblll, 1983; Welsburger, 1983). Hexachlorobenzene 1s
1n a different chemical class from these agents.
Induction of thyroid tumors 1n the animal studies 1s of particular
Interest because a very high Incidence of thyroid "tumors" (most of which
have not been examined h1stolog1cally as a result of surgery or biopsy) 1s
found among victims of accidental exposure to hexachlorobenzene 1n Turkey
(Peters, 1983). The Incidence among females, over 25 years after the Inci-
dent, 1s 61.4% whereas the background Incidence 1n that geographic area for
females 1s about 5% (Peters, 1983). The data and pathology reports have not
been made available yet, but 1t 1s clear that the cohort exposed to hexa-
chlorobenzene has an unexpectedly high Incidence of enlarged thyroid.
While the average dosages used 1n the study were 4, 8 or 16 mg/kg/day
the effective doses are likely to be lower. A number of studies on the
absorption of hexachlorobenzene have been conducted (Albro and Thomas, 1974;
Mehendale et al., 1975; Koss and Koransky, 1975; Ingebrlgsten et al., 1981)
which Indicate that 1n an appropriate solvent, such as corn oil, absorption
Is on the order of 70-80%. Further, hexachlorobenzene distributes Itself to
various tissue compartments unevenly. Tables 12-17 and 12-18 show the tis-
sue distribution for rats. Zablk and Schemmel (1980) reported that the com-
position of the diet affects the tissue storage of hexachlorobenzene. It 1s
reasonable to assume that 1n this hamster study of Cabral et al. (1977) por-
tions of the absorbed dose were sequestered 1n the fat and mobilized only
when fat stores were utilized (I.e., 1f the animals lost weight). Indeed
Vllleneuve and Newsome (1975) have shown that when rats were fed hexachloro-
1835A 12-63 04/16/84
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TABLE 12-17
HCB Levels 1n Tissues of Male Rats Following Administration of
8 mg/kg 1n Sunflower 011 for 19 Days*
Tissue HCB Level
Fat tissue 82 ppm
Muscle 17 ppm
Liver 125 pg
Kidneys 12 pg
Spleen 9 pg
Heart 1.5 pg
*Source: Engst et al., 1976
HCB - Hexachlorobenzene
1835A 12-64 03/23/84
-------
TABLE 12-18
HCB Levels 1n Tissues of Male Rats Following Administration of 14C-HCB
1n Arachls 011. Measurement 7 Days After Single Dose of 5 mg/kga
Organ or Tissue % Total Radioactivity Administered
Fatb 42.81 i 6.14
Muscle0 9.41 ± 1.17
Sk1nd 8.64 ± 1.21
Liver 3.01 ± 0.23
Small Intestine 2.43 + 0.47
Bone6 1.04 + 0.09
Kidneys 0.76 +_ 0.11
Large Intestine 0.43 +_ 0.08
Stomach 0.36 + 0.04
Blood 0.24 + 0.04
Lungs 0.24 + 0.04
Testes 0.21 ± 0.04
Heart 0.18 ± 0.03
Brain 0.17 + 0.03
Spleen 0.04 + 0.002
Total 1n tissues 70.09 + 5.48
Excretion
Feces 16.02 + 2.31f
Urine 0.85 ± 0.13^
Gut contents 2.48 _t 0.45
Total recovery 89.44 t 10.57
aSource: Mehendale et al., 1975
Based on 9% body weight as fat
Based on 50% body weight as muscle
Based on 16% body weight as skin
Q
Based on 10% body weight as bone
Cumulative total for 7 days
HCB = Hexachlorobenzene
1835A 12-65 03/23/84
-------
benzene followed by a normal Intake of hexachlorobenzene-free diet, hexa-
chlorobenzene was not mobilized from the fat stores. If, however, the hexa-
chlorobenzene-containlng diet was followed by an hexachlorobenzene diet
which was restricted 1n calories, causing the animals to mobilize their fat
stores, then the stored hexachlorobenzene was mobilized and redistributed to
other tissues as the fat stores were utilized. The effective dose of hexa-
chlorobenzene will, therefore, be expected to vary 1n a chronic hexachloro-
benzene study depending upon whether hexachlorobenzene has accumulated 1n
existing fat and remains there as a sink, or whether such stores are mobi-
lized, and at what rates. In the early stages of treatment, when the ani-
mals are growing, 1f the dose 1s not adjusted to body weight, the effective
dose will reflect the greater proportional food Intake/body weight char-
acteristic of the growing animal. Later the effective dose could be higher
than the administered level because 1t will consist of the amount taken In
as well as the amount released from sequestered stores. These mechanisms
should apply to hamsters as well as to the rats.
Since Cabral et al. (1977) did not report the actual weight data 1n
their hamster study and since accompanying pharmacoklnetlc data are not
available, 1t 1s not possible to make quantitative evaluation of the hexa-
chlorobenzene contribution to, or from, stored compartments 1n order to
determine effective dose. However, consideration of the absorption factors,
and on the assumption that for a major part of the treated animal's life it
deposited some of the administered hexachlorobenzene in fat stores, it is
reasonable to conclude that the effective dose will be somewhat below the
administered dose. If a figure of 75% absorption 1s used, then the lowest
dose used in the study, 4 mg/kg bw/day, is effectively closer to 3 mg/kg
bw/day. At that dosage the incidence of hepatoma was 47% and the Incidence
1835A 12-66 03/23/84
-------
of thyroid adenomas was 7% among female hamsters, and at this same dose 1n
males the hepatoma Incidence was 47X and the Incidence of liver haemanglo-
endothelloma was 3%. Unfortunately, Information 1s not available about the
total number of weeks on test, or the time of death for the animals with
tumors, so that total doses cannot be calculated from Information supplied
1n the published report. These facts would be useful 1n calculation of
potency of hexachlorobenzene 1n hamsters.
This hamster study provides strong positive evidence of tumor1gen1dty
and evidence of carclnogenldty of hexachlorobenzene, as Indicated by the
significant Increase 1n hepatomas, significant Increase of thyroid adenomas
1n males and the occurrence of metastaslzlng liver haemang1oendothel1omas 1n
treated but not 1n control animals. Although not reported 1n detail 1n this
one page publication, the authors noted an Increase In adrenal neoplasms as
well. The data presented show that the tumor Incidence 1s positively dose-
dependent 1n most Instances and that this 1s true not only of the number of
animals with tumors of all sites but also for the number of tumors per ani-
mal. The authors also Indicated that latency period was reduced, but actual
supporting data was not presented.
12.3.5.1.2. Lambrecht et al. (1982a) Hamster Study — Another study on
hamsters, carried out 1n a different laboratory, adds further suggestive
evidence for the tumor1gen1c1ty of hexachlorobenzene 1n hamsters (Lambrecht
et al., 1982a). This study, reported only 1n abstract form, was also
carried out 1n the Syrian golden hamster. In this study the animals were
exposed for only 90 days to the hexachlorobenzene. On day 91, half of the
Initial exposed 50 animals were sacrificed. The remaining animals were
sacrificed periodically until the end of the 1-year study. The exposure
levels used were 200 or 400 ppm hexachlorobenzene 1n the diet. Assuming
1835A 12-67 04/16/84
-------
that the hamsters from the Cabral (1977) study were comparable 1n weight and
dietary consumption, these ppm figures would be approximately equal to and
twice those of the high dose used 1n the lifetime studies of Cabral et al.,
1977). Lambrecht et al. (1982a) reported the Incidence of hepatoma at the
200 ppm level to be 7.7% 1n males and 6.7% 1n females; at the 400 ppm level
the Incidence was 5% 1n females and 14.3% 1n males. These figures are based
on the numbers of animals at risk at the time of the earliest observed
tumor. The time to first tumor was relatively late 1n the study, 276 days
for males and 255 days for females of the lower dose and 153 days for males
and 299 days for females at the higher dose. Since the test animals were
systematically sacrificed from 3 months onward, the time to tumor figures
should be reasonably close to actual time to tumor. Table 12-19 shows the
results reported by Lambrecht et al. (1982a).
The tumor1gen1c1ty and cardnogenlcHy of hexachlorobenzene has been
demonstrated by one lifetime study 1n hamsters. Additional suggestive evi-
dence for tumor1gen1c1ty 1s found 1n a 90-day study 1n another laboratory.
In both cases hepatomas resulted. The longer period of exposure also
produced thyroid adenomas and metastatlc liver haemangloendothelloma.
12.3.5.2. MOUSE STUDIES —
12.3.5.2.1. Cabral et al. (1979) - Cabral et al. (1979) reported that
outbred Swiss mice were fed hexachlorobenzene (99.5% purity) 1n their diets
for up to 120 weeks. The hexachlorobenzene content of the diet was mon-
itored periodically during the study and the diet was found to be free of
aflatoxlns. The exposure levels used were 50, 100 and 200 ppm corresponding
to dosages of 6, 12 or 24 mg/kg/day based on body weight and food Intake
averages. One other test group was given 300 ppm (36 mg/kg/day) for only 15
weeks and retained on an hexachlorobenzene-free diet for the remainder of
the study.
1835A 12-68 04/16/84
-------
TABLE 12-19
Effect of HCB on Hamsters: Liver Tumors and Other Liver Lesions^
Sex
M
F
HCB
(ppm)
0
200
400
0
200
400
PC+Cb
Incidence
3/50
48/49
50/50
10/43
48/49
45/45
BDHC
Incidence
0
0
1/25
0
1/6
2/20
Day First Hepatomas
Observed Incidence
0
1/13
101 1/20
0
340 1/15
174 1/7
Day First
Observed
276
153
255
299
aSource: Lambrecht et al., 1982a
bPredrrhot1c + clrrhotlc
cB1!1ary duct hyperplasla
HCB = Hexachlorobenzene
1835A
12-69
03/30/84
-------
Growth rates were monitored but not given 1n detail 1n the published
report. The Investigators stated that among female mice there was a reduced
growth rate for all doses except 1n the 12 mg/kg/day dose group and among
males for all doses except In the 6 mg/kg/day dosage group.
Survival times were reported 1n detail. Survival was essentially
unaffected In the two lower dosage level groups at 50 weeks, while at that
time 1t was down by 60% of the original number 1n the females and 52% of the
original number 1n the males 1n the highest dosage group. By 70 weeks on
test the survival was decreased 1n the two lower dose groups as well, and 1n
the highest dose group 1t was down to 14% 1n females and 10% 1n males. At
90 weeks there were only four surviving males out of the 50 and no surviving
females In the highest dosage group as compared with 96 and 100% survival 1n
the female and male controls.
The yield of tumors 1n this study 1s given 1n Tables 12-20 and 12-21.
In Table 12-20, the effective number of animals 1s the number of animals
alive at the earliest time a liver cell tumor was observed In each group
while In Table 12-21 the effective number of animals 1s that number of
animals alive at the earliest appearing tumor for any site In the body
within that group. There was a statistically significant elevation 1n the
Incidence of liver cell tumors at the high dose 1n females and a marginal
Increase 1n high-dose males, with a positive dose-related trend In both
cases. There was also a dose-dependent decrease 1n latent period and a
dose-dependent Increase 1n the size and multiplicity of liver cell tumors
(Table 12-20). The liver cell tumors were subsequently defined as hepatomas
(Cabral, 1983).
1835A 12-70 03/30/84
-------
CO
CO
en
3*
TABLE 12-20
Liver Tumor Incidence 1n Mice Fed HCBa
o
CO
INJ
CO
CO
Group
HCB 100
HCB 200
HCB 300
(15 weeks
exposure)
Effect1veb
No.
Animals
F 12
M 12
F 26
M 29
F 10
M 3
Mice with LCT
No.
3
3
14
7
1
1
%
25
25
54
24
10
33
Node S1
<8
2
1
5
4
__
—
ze (mm)
>8
1
2
9
3
1
1
Multiplicity
Single
1
2
3
2
1
--
Multiple
2
1
11
5
__
1
Aqe at Death (weeks)
Range
87-104
83-98
47-85
46-101
101
97
Average
98
89
67
73
101
97
aSource: Cabral et a!., 1979
DSurv1vors at time first LCT was observed 1n each group
LCT = Liver cell tumors
HCB = Hexachlorobenzene
-------
TABLE 12-21
CD
CO
cn
3*
Tumor Data on Mice Fed HCBa
Animals with Tumors
Lymphomas
Group
Control
HCB 50
HCB 100
HCB 200
^, HCB 300
ro (15 weeks)
Initial
No.
Animals
F 50
M 50
F 30
M 30
F 30
M 30
F 50
M 50
F 30
M 30
Effective0
No.
Animals
49
47
30
30
30
29
41
44
26
16
Lung
TBAC
No.
39
22
21
15
13
10
19
12
20
5
X
80
47
70
50
43
34
46
27
77
31
No.
21
12
16
13
5
7
5
4
8
3
X
43
26
53
43
17
24
12
9
31
19
Average Age
at Death
(weeks)
89.6
80.8
69.8
73.7
94.4
70.4
58.2
53.2
97.7
68.6
No.
14
13
4
4
6
0
2
4
4
2
X
29
28
13
13
20
0
5
9
15
13
Average Age
at Death
(weeks)
89.0
83.8
84.5
87.0
83.5
--
66.5
82.5
91.2
83.5
Liver-cell
No.
0
0
0
0
3
3
14
7
1
1
%
0
0
0
0
10
10
34
16
4
6
Gonads
No.
3
0
2
0
1
0
1
1
3
0
X
6
0
7
0
3
0
2
2
12
0
Other
No.
9d
4e
2*
0
39
1"
11
0
83
0
%
18
9
7
U
10
3
2
U
31
U
o
CO
ro
CO
CD
aSource: Cabral et a!., 1979
bNumber of survivors at moment of appearance of first tumor at any site 1n each group
cln relation to the effective number
dSk1n f Ibrosarcoma, uterine haemangloendothelloma, one skin haemangloendothelloma, two adrenal adenoma, two mammary adenoma
eUr1nary bladder transition cell carcinoma, one liver haemangloendothelloma, one skin haemangloendothelloma, one skin flbrosarcoma
fflne uterine haemangloendothelloma, one skin flbrosarcoma
9Two skin flbrosarcoma, one skin haemangloendothelloma
nOne skin squamous-cell carcinoma
^One Intestinal lelomyosarcoma
skin flbrosarcoma, two liver haemangloendothelloma, one cecum carcinoma, one stomach papllloma, one skin haemangloendothelloma, one
uterine adenoma, one mammary adenoma
HCB = Hexachlorobenzene
-------
In this study there was a high Incidence of both lymphoma and lung
tumors 1n control mice. A dose-related decrease 1n the Incidence of lympho-
mas appears In the treated groups. The Investigators attributed this to the
decreased survival time of hexachlorobenzene-treated animals. This seems
reasonable but does not explain the reduction 1n lung tumors In the 50 ppm
(6 mg/kg/day) group when they are compared to controls, since there was not
an appreciable reduction of Hfespan 1n this low dose group.
This study by Cabral (1979) demonstrates the tumor1gen1c1ty of hexa-
chlorobenzene 1n Swiss mice by the significant Increase 1n liver cell tumors
In both sexes and by the demonstration of dose-dependency 1n the response
with respect to tumor Incidence, tumor size, multiplicity and latent period
duration. Tumor1gen1c1ty was detected as low as 12 mg/kg bw/day (100 ppm)
for lifetime exposure but not at 6 mg/kg bw/day (50 ppm).
12.3.5.2.2. Lambrecht et al. (1982b) — Swiss mice exposed to hexa-
chlorobenzene for only 90 days at levels of 100 and 200 ppm 1n the diet
showed degenerative changes of liver and kidneys when examined at various
Intervals after they were removed from the hexachlorobenzene-contalnlng diet
(Lambrecht et al., 1982b). Although liver tumors were not reported, treated
animals showed lymphosarcomas 1n both dosage groups 1n both sexes at levels
significantly above those of controls. Exposure to hexachlorobenzene 1n
this Instance produced leukemogenlc changes. The animals were not permitted
to live beyond selected Intermediate sacrifice dates, so H was not possible
to determine whether survivors would have developed liver or other tumors.
The method of preparation of the hexachlorobenzene-contalnlng diet may have
been different In the Cabral et al. (1979) and Lambrecht et al. (1982b)
studies, but detailed Information was not presented 1n the Lambrecht et al.
(1982b) abstract.
1835A 12-73 03/30/84
-------
Mice may be somewhat less sensitive than hamsters to hexachlorobenzene
as evidenced by the difference 1n Incidence of hepatoma formation at various
doses. These animal species may differ 1n the distribution of the hexa-
chlorobenzene Into various tissue compartments (Lambrecht et al., 1981), and
differ 1n rates of metabolism and absorption. Administration of the same
levels of hexachlorobenzene 1n the feed can be expected to give different
effective dosages.
12.3.5.2.3. Shiral et al. (1978) — Sh1ra1 et al. (1978) administered
hexachlorobenzene to male ICR mice (35 animals/group) at levels of 10 or 50
ppm 1n the diet for periods of 24 weeks. Polychlorinated terphenyl was
given alone to another group at 250 ppm, and in combination with 50 ppm
hexachlorobenzene to a third group. Animals were examined histologically at
40 weeks.
Final body weights were slightly lower in the hexachlorobenzene-treated
groups while liver weights were higher. Examination of the livers showed
that the hexachlorobenzene-treated groups had hypertrophy of the centri-
lobular area at both doses. No liver tumors were found in either group.
The total Intake of hexachlorobenzene was calculated to be 8.4 and 3S.3
mg/mouse of the 10 ppm and 50 ppm groups, respectively.
Polychlorinated terphenyl alone, at 250 pom (total dose 207.4 mg/mouse)
gave 3/28 (10.7%) nodular hyperplasla. When this same level of polychlori-
nated terphenyl was given along with hexachlorobenzene at 50 ppm (total dose
36.9 mg/ mouse) there were 23/26 (88.5%) nodular hyperplasia and 8/26
(30.8%) hepatocellular carcinoma. This response Indicates that hexachloro-
benzene can enhance the carcinogenic potency of polychlorinated terphenyl.
The duration of administration, 24 weeks, in this mouse study and the
doses used were below those used in the Cabral (1979) study on Swiss mice
1835A 12-74 03/30/84
-------
and also below the levels used 1n the 13-week study by Lambrecht (1982b) on
Swiss mice. Therefore, H 1s not surprising that hepatomas were not found
when hexachlorobenzene was given alone. The occurrence of liver lesions,
however, does Indicate target organ toxldty.
These three studies 1n mice demonstrate the tumor1gen1c1ty of hexa-
chlorobenzene with respect to the Induction of hepatomas, the leukemogenlc
effect of subchronlc exposure and the ability of hexachlorobenzene to
enhance the carcinogenic effect of another compound.
12.3.5.3. RAT STUDIES —
12.3.5.3.1. Smith and Cabral (1980) — The carcinogenic potential of
hexachlorobenzene was tested 1n several different laboratories 1n rats. In
one study (Smith and Cabral, 1980) small numbers of female Agus rats, and
even smaller numbers of female Wlstar rats, were used. There were 12 con-
trol and 14 treated Agus rats and 4 control and 6 treated Wlstar rats. The
hexachlorobenzene was analytical grade (99.5% purity) dissolved 1n arachls
oil and mixed with the feed to give 100 ppm 1n the diet. This dietary level
supplied an average dally dose of 6-8 mg/kg/day to the rats.
In this study the Agus rats showed signs of porphyrla after 3 months
exposure to hexachlorobenzene, but other toxic manifestations were not
found. The Investigators stated that "there was a steady decline 1n body
weight to eventually 80% of control animals" (Table 12-22). Examination of
the weight data presented 1n the publication Indicates that this Interpreta-
tion 1s based upon comparison of "final" average weight 1n control
(286^19 g) and treated (225+16 g) animals (Table 12-22), representing a 21%
difference 1n weight. This method of comparison can be misleading since the
final weights represent accumulated differences 1n growth rates and varying
1835A 12-75 03/30/84
-------
TABLE 12-22
Body Weights of Female Agus Rats Fed Hexachlorobenzene for 90 Weeks3
Body Weight (g)
eeks of Diet
0
10
30
50
90
Control
46 +
191 i
236 t
257 ±
286 +
6 (8)
5
13
17
19 (8)
HCB
45 i 24 (9)
180 i 17
212 ± 13b
221 i 19C
225 i 16 (7)c
% Difference
2
6
10
14
21
aSource: Smith and Cabral, 1980
bS1gn1f1cantly different from controls as assessed by Student's t-test
p<0.01
cp<0.001
Female Agus rats were fed HCB (100 ppm) 1n MRC 41B diet for 90 weeks and
then killed. Weights are menas (no. of animals In parentheses) + S.D.
HCB = Hexachlorobenzene
1835A 12-76 03/30/84
-------
composition of the groups because of animal deaths. An effect produced,
even transiently, at an early age, may persist 1n the figures, even though
all subsequent growth may be normal. Growth rates, rather than absolute
difference 1n weights provide a more suitable picture of the animal
response. Growth rates for the time Intervals reported were calculated
based on the data given 1n the publication and are shown 1n Table 12-23.
The equation used was:
weight at end of Interval - weight at start of Interval ,„„
R = x 100
weight at start of Interval
According to this calculation both groups of animals grew during each time
Interval.
The survival of the treated Agus rats was good; one test animal was
sacrificed at 52 weeks and a second one died of pneumonia at 70 weeks. Both
of these animals had liver cell tumors found by hlstologlc examination.
Another five treated animals were sacrificed at 75 weeks and the remaining
seven treated animals lived until the end of the experiment at 90 weeks.
Among controls, one was killed at 63 weeks and three more at 75 weeks. The
remaining eight were killed at 90 weeks.
No control animals had liver pathology. In contrast, 14/14 (100%) of
the treated Agus rats had liver tumors; the earliest of these was detected
at 52 weeks. The livers of the treated animals were grossly enlarged and
some of the tumors were 1.5-2 cm 1n diameter. Although one liver cell tumor
was described as pedunculated, hlstopathology detail was not given, except
to note the absence of metastases 1n all cases. Four of the six (67%)
Wlstar rats also had liver cell tumors and none of the four controls showed
such pathology at 75 weeks.
1835A 12-77 03/30/84
-------
TABLE 12-23
Growth Rates for Female Agus Rats on a Diet Containing 100 ppm HCB*
Average Growth Rate %/week
Interval (on diet)
0-10 weeks
10-30 weeks
30-50 weeks
50-90 weeks
Control
31.5
1.2
0.45
0.28
Treated
30.0
0.89
0.22
0.05
*Source: Calculated from Smith and Cabral, 1980
HCB = Hexachlorobenzene
1835A
12-78
03/30/84
-------
In this rat study hexachlorobenzene was a potent Inducer of liver
tumors, causing a 100% Incidence with the earliest tumor observed at 52
weeks. It 1s Important to determine whether the magnitude of the effect 1s
all attributable to the hexachlorobenzene or whether contaminants, unusual
characteristics of the test animals, or procedural factors were operative 1n
this study. In this context the following points are noted.
First, historical control data on tumor Incidence for Agus rats were not
available, but, according to Cabral (1983), the Agus rat 1s a strain partic-
ularly sensitive to porphyrla and hepatic tumors. In regard to the question
of contaminants, peanut oil 1s generally believed to be free of aflatoxlns
[they are destroyed 1n processing (MAS, 1977)] and the feed was analyzed for
both aflatoxlns and dlbenzofurans and found to be free of both (Cabral,
1983). Absorption 1s another factor to consider. The absorption of the
hexachlorobenzene 1n these animals might be enhanced by dissolution 1n the
arachls oil.
12.3.5.3.2. Lambrecht et al. (1983a,b, 1984) — Another study on rats
was carried out by Lambrecht et al. (1983a,b, 1984). In this study 94
Sprague-Dawley rats of each sex for each dosage and control groups were
used. Four animals of each group were sacrificed at each of 10 Intervals:
0, 1, 2, 3, 4, 16, 32, 48 and 64 weeks. The remaining 54 animals of each
group were allowed to continue until they died, or to the end of the 2
years. The number of animals at risk was considered to be those that sur-
vived at least 12 months, since this was the earliest time to tumor. This
number would be, at minimum, 54 plus some animals from the last sacrifice
time.
The hexachlorobenzene was highly purified and the prepared diet moni-
tored for hexachlorobenzene levels periodically. The preparation was also
1874A 12-79 04/16/84
-------
analyzed for aflatoxlns and found to be negative. The test diet was
prepared by mixing the hexachlorobenzene with dextrose and Wayne laboratory
feed (1.5 g hexachlorobenzene + 98.5 g dextrose + 9.9 kg lab chow to give
150 ppm hexachlorobenzene). Half the amount of hexachlorobenzene was used
1n the mix for the 75 ppm hexachlorobenzene level. This oil-free vehicle 1s
different from the vehicle used by both Smith and Cabral (1980) and Arnold
et al. (1983). The hexachlorobenzene was well absorbed as shown by progres-
sive accumulation 1n fat which was measured 1n this study.
Based on an average food consumption of 22.6 g/rat/day for males and
16.5 g/rat/day for females, and on an average adult weight for females of
265 g and for males of 400 g, the low dose was calculated to be 4-5 mg/kg/
day and the high dose, 8-9.5 mg/kg/day. In order to compare the results
obtained 1n this study with those obtained 1n Sprague-Dawley rats by Arnold
et al. (1983), more detailed calculation of doses at different time periods
on test are given 1n Table 12-24.
The administration of hexachlorobenzene 1n the diet at these doses 1n
the Lambrecht et al. (1983a) chronic feeding study 1n rats resulted 1n liver
pathology just before the appearance of hepatoma or hepatocellular «arc1-
noma. Pathology observed at the early sacrifice time Included parenchymal
degeneration, preneoplastlc fod and adenoma. At 48 and 64 weeks of the
test females had gross liver tumors which measured between 1 and 2 mm2.
Porphyrla was also detected.
Rats that lived 12 months or longer showed a significant Increase 1n
hepatoma Incidence 1n both sexes. A statistically significant Increase 1n
the Incidence of hepatocellular carcinoma was found at both doses 1n the
females, and 1n males a slight non-significant Increase was found. None of
the liver cell tumors metastaslzed. Table 12-25 summarizes the findings.
1874A 12-80 03/30/84
-------
TABLE 12-24
Dosage Levels 1n the Chronic Feeding Study of Hexachlorobenzene
1n Sprague-Dawley Rats3
(mg/kg/day)
Time on D1etb
(weeks)
0
26
52C
79
99
Males
75 ppm
19.5
3.2
3.3
3.4
6.2
150 ppm
37.0
7.1
6.4
6.7
10.0
Females
75 ppm
16.1
3.7
3.8
3.5
4.3
150 ppm
32.2
8.7
8.0
8.4
10.6
aSource: Calculations and data provided by Lambrecht, 1984
animals were 3 weeks old when placed on test
cAt 52 weeks on test the males consumed an average of 24.7 g of the diet/
day and weighed an average of 553.7 g. The females consumed an average of
16.0 g diet/day and weighed an average of 311.7 g.
1874A 12-81 03/26/84
-------
TABLE 12-25
Liver and Kidney Tumors 1n Sprague-Dawley Rats Given Hexachlorobenzene
1n the Diet for up to 2 yearsa»b
Exposure
Level
0
percentage
75 ppm
percentage
150 ppm
percentage
Hepatoma
M
0/54
0
10/52
19
11/56
20
F
0/52
0
26/56
46
35/55
64
Hepatocellular
Carcinoma
M
0/54
0
3/52
6
4/56
7
F
0/52
0
36/56
64
48/55
87
Renal Cell
Adenoma
M
7/54
13
41/52
79
42/56
75
F
1/52
2
7/56
13
15/54
28
Renal Cell
Carcinoma
M
0/54
0
0/52
0
0/56
0
F
1/52
2
2/56
4
2/54
4
aSource: Lambrecht et al., 1983a,b; Lambrecht, 1983
bThe diet was prepared without solub1!1zat1on of the hexachlorobenzene,
but by mixing 1t as a pulverized solid.
1874A
12-82
03/26/84
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Renal cell adenoma was found to be significantly elevated 1n both sexes
but with greater frequency 1n males. In this study the control male group
had a high Incidence of renal cell adenoma which was not explained; never-
theless, the Increase In the hexachlorobenzene-treated animals was statis-
tically significant. The Incidence of renal cell carcinoma 1n treated
animals was not significantly Increased over control animals 1n either males
or females.
In an updated report from this laboratory (Peters et al., 1983) hlsto-
pathology details were supplied. These data show that 1n addition to the
liver and kidney lesions there was an Increase 1n adrenal pheochromocytoma
1n female rats which was statistically significant at both 75 and 150 ppm.
Females also had elevated Incidences of adrenal cortical adenoma and
hemangloma 1n the treated groups. Among males the background Incidence of
adrenal pheochromocytomas 1s high (76.5%), making 1t difficult to determine
whether the 90.6% Incidence found 1n the 150 ppm group has any biological
significance. Other adrenal neoplastlc and non-neoplast1c lesions were
detailed: hyperemla and/or congestion, cortical hyperplasla, preneoplastlc
foci, cysts, Upoma and adenocardnoma; none of these were elevated 1n the
treated animals. The adrenal tumor Incidences are given 1n Table 12-26.
One point to consider 1n the Interpretation of the results, particularly
In terms of their application to risk assessment, 1s the form 1n which the
hexachlorobenzene was administered 1n the diet. The absorption from a
partlculate form Introduces an additional possible exposure route, namely,
from the food preparation by Inhalation. This consideration does not
Invalidate the study, but raises the question of the actual exposure levels
1f an additional route of exposure was occurring 1n the same experiment
simultaneously with oral 1ngest1on.
1874A 12-83 03/30/84
-------
TABLE 12-26
Adrenal Tumors 1n Sprague-Oawley Rats Given Hexachlorobenzene
1n the Diet for up to 2 Yearsa«b
MALES
Days on diet
Exposure ppm
hexachlorobenzene
Number of tissues
examined
Cortical adenoma
(X)
Pheochromocytoma
(X)
Hemangloma (%)
400-599
0 75 150
17 23 28
326
369
(17.6) (26.1) (32.1)
000
0
34
6
26
(76.5)
0
600+
75
25
3
17
(68)
0
150
23
4
21
(91.
0
3)
FEMALES
Days on diet
Exposure ppm
hexachlorobenzene
Number of tissues
examined
Cortical adenoma
(X)
Pheochromocytoma
(X)
Hemangloma (%)
400-599
0 75 150
12 5 13
032
002
002
0
35
2
(5.7)
5
(14.3)
3
(8.5)
600+
75
47
11
(23.4)
31
(66)
8
(17)
150
32
6
(18.
29
(90.
5
(15.
8)
6)
6)
aSource: Peters et al., 1983
diet was prepared without solub1!1zat1on of the hexachlorobenzene,
but by mixing 1t as a pulverized solid.
1874A
12-84
03/30/84
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12.3.5.3.3. Arnold et al. (1983) — Another study (an unpublished 1983
draft, amended 1n 1984) on Sprague-Dawley rats was carried out at the
Canadian Health Protection Branch of the Canadian Health Ministry (Arnold et
al., 1983). This 2-generat1on study has been completed, but not yet pub-
lished. Our data were derived from the draft of the manuscript to be sub-
mitted for publication and from personal communication with Or. Arnold of
the Canadian Health Ministry.
In this study hexachlorobenzene (99X pure) was administered to parental
male and female Sprague-Dawley rats for 3 months. These animals were mated
at that time and the females continued to receive hexachlorobenzene-contaln-
1ng diets during pregnancy and throughout lactation. At weaning, 50 pups of
each sex were separated and fed for the remainder of their lifetime on hexa-
chlorobenzene-contalnlng diets. Controls were fed diets free of hexachloro-
benzene. The range of doses used 1n this study 1s considerably lower than
those used by either Smith and Cabral (1980) or Lambrecht et al. (1983a,b).
Table 12-27 shows the doses used 1n the Arnold et al. study at particular
points 1n time since the doses were not adjusted throughout the study.
These doses represent a greater exposure to the test animals from the point
of view of exposure duration, since the F, animals were exposed 1n utero
1
and during nursing 1n addition to their exposure from feeding on an hexa-
chlorobenzene-contalnlng diet. Total doses cannot be calculated since the
actual dose received during nursing 1s not known.
Arnold et al. (1983) found no differences 1n treated animals when com-
pared to controls with respect to growth rates, food consumption, hematology
or survival except at the highest dose used. At this dose, F pups had a
significantly Increased mortality.
1874A 12-85 03/30/84
-------
TABLE 12-27
Exposure Levels 1n the Chronic Feeding, 2-Generat1on Study of
Hexachlorobenzene 1n Sprague-Dawley Ratsa
(mg/kg/day)
Time on D1etb
(weeks)
1
30C
70
1
30C
70
Exposure Level
0.32 ppm
0.04
0.01
0.01
0.04
0.02
0.01
1 .6 ppm
MALES
—
0.06
0.05
FEMALES
0.17
0.08
0.06
8.0 ppm
0.93
0.29
0.25
0.84
0.40
0.32
40.0 ppm
4.85
1.5
1.3
4.64
1.9
1.6
aSource: Calculations and data provided by Arnold, 1984
bThe animals were placed on feed at 6 weeks of age.
cThe mean body weight of male controls was 663 g and for the highest dose
group males 653 g. The mean weekly food consumption for male controls at
that time was 178 g and for the highest dose group 169 g. Females of the
same age weighed 351 g for controls and 353 g for the highest dose treated
group and the mean weekly food consumption was 113 and 118 g, respectively.
1874A 12-86 03/30/84
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Hlstopathology showed that F-, females had a significant elevation 1n
neoplastlc Hver nodules and 1n adrenal pheochromocytoma 1n the high dose
females compared to controls (Table 12-28). There was also a significant
positive dose-related trend 1n the Incidence of these tumors 1n F females.
Among F, males, 1n the highest dose group parathyroid tumors were
significantly increased: 25% (12/48) 1n the treated groups and 4.2% (2/48)
among controls. Females also showed a few parathyroid tumors 1n the two
highest dose groups and none 1n controls or 1n the two lowest dose groups,
but the differences were not statistically significant. Table 12-28 gives
the tumor Incidences. Although kidney tumors were not reported to be ele-
vated, there was an Increased chronic nephrosls 1n the F treated animals.
12.3.5.3.4. Arnold et al. (1983) — In another study by Arnold et al.
(1983) which was related to the 2-generat1on study, the effect of vitamin A
In a synthetic diet was tested 1n conjunction with hexachlorobenzene. This
was a l-generat1on study and the level of hexachlorobenzene was the same as
the highest dose of the 2-generat1on study, 40 ppm. There were six separate
groups of 50 animals each and the experiment ran for 119 weeks. At 29 weeks
and at 49 weeks five animals from each group were sacrificed and evaluated
h1stolog1cally. The six groups are shown 1n Table 12-29. The vitamin A did
not apparently alter the effects of hexachlorobenzene. The number of
animals with parathyroid tumors and adrenal pheochromocytomas was somewhat
elevated 1n all the cases In which hexachlorobenzene was administered
compared with the total cases with the three levels of vitamin A and no
hexachlorobenzene. The significance of these tumor Incidences cannot be
determined by simple comparison because 1t was also found 1n the study that
vitamin A had an effect on the background level of some common tumors and
these data have not yet been completely analyzed.
1874A 12-87 03/30/84
-------
CO
TABLE 12-28
Tumors 1n Organs that Showed Statistical Differences from Control 1n F-| Sprague-Dawley Rats Treated with Hexachlorobenzenea
[Incidence (X)]
Parathyroid Adenoma
ro
i
CD
CD
o
CO
\
0
»w
^
CO
Dose at 30 weeks
(mg/kg bw/day)
Controls
0.01-0.02
0.06-0.08
0.29-0.40
1.5-1.9
Other statistical tests
IARC trend test
ArmHage time-related
trend test
Fisher exact
treated vs. control
aSource: Arnold et al . ,
Males
2/48 (4.2)
4/48 (8.3)
2/48 (4.2)
1/49 (2.0)
12/49 (24.5)
p<0.01
p<0.01
1983; Arnold
bD1fferent results of two different
Females
0/49 (0)
0/49 (0)
0/50 (0)
1/49 (2.
2/49 (4.
p<0.01
p<0.05
. 1984
pathologlsts
Adrenal Pheochromocytoma
Males Females
10/48 (20.8) 2/49 (4.1)
12/48 (25.0) 4/49 (8.0)
7/48 (14.6) 4/50 (8.0)
0) 13/49 (26.5) 4/49 (10.2)
1) 17/49 (34.7) 17/49 (34,7)
p<0.01
p<0.01
p<0.01
reading the same slides
Hepatocellular Carcinoma
Males Females
0/48 (0) 0/49 (0)
2/48 (4.2) 0/49 (0)
1/48 (2.1) 0/49 (0)b
1/49 (2.0)b
3/49 (6.1) 0/50 (0)
0/49 (0) 0/49 (0)b
1/49 (2.0)b
Neoplastlc Liver Nodules
Males Females
2/48 (4.2) 0/49 (0)
0/48 (0) 0/49 (0)
0/48 (0) 2/50 (4.0)
2/49 (4.1)b 2/49 (4.1)b
3/49 (6.1)b 3/49 (6.1)b
1/49 (2.0) 10/49 (20.4)b
9/49 (18.4)b
p<0.01
p<0.01
p<0.01
-------
TABLE 12-29
Parathyroid and Adrenal Pheochromocytomas 1n Sprague-Oawley Rats
Maintained on Synthetic Diets of Varying VHamln A Content and
With or Without Hexachlorobenzene*
Group No. with
Parathyroid Tumors
Controls on diet with normal
vitamin A content
Control diet t 40 ppm HCB
Diet with 0.1 times normal vitamin A
Diet with 0.1 times normal
vitamin A + 40 ppm HCB
Diet with 10X vitamin A
Diet with 10X vitamin A + 40 ppm HCB
Total without HCB
Total with HCB 40 ppm
3
4
0
0
1
3
4
7
No. with Adrenal
Pheochromocytoma
3
6
2
2
4
7
9
15
*Source: Arnold et al., 1983
HCB = Hexachlorobenzene
1874A 12-89 03/30/84
-------
12.3.5.4. DISCUSSION OF RAT STUDIES — It seems appropriate to compare
the findings of Smith and Cabral (1980) 1n Agus and Wlstar rats, Lambrecht
et al. (1983a,b) and Arnold et al. (1983) In Sprague-Dawley rats. None of
the three studies agree precisely on all four of the tumor target organs:
Smith and Cabral reported liver tumors, Lambrecht reported liver, adrenal
and kidney tumors and had some liver carcinomas not found by Smith and
Cabral. Arnold found adrenal and parathyroid tumors and neoplastlc liver
nodules but no Increase 1n kidney tumors. We find that, although differ-
ences do occur, the results are not contradictory for the following reasons:
1. The dosages used 1n the Arnold et al. (1983) study were below those used
by either Smith and Cabral (1980) or Lambrecht et al. (1983a,b). The
range of doses used by Smith and Cabral was given as 5-8 mg/kg/day and
those used by Lambrecht were 3-9 mg/kg bw/day. Those of Arnold were, at
most, between 1.5 and 2.0 mg/kg bw/day.
2. There were notable differences 1n the animals used: 1n the case of
Smith and Cabral the liver tumor susceptible strain of Agus rat was
used, although tumors were also found with Wlstar rats. We do not have
full data on historical tumor Incidences 1n these animals to allow for
more detailed evaluation.
3. The conditions of the Smith and Cabral study and those of Lambrecht were
both different from the 2-generat1on study of Arnold. The possible
effects prenatal exposure could have on metabolism of xenoblotlcs
renders this an Important consideration.
4. The method of preparation of the hexachlorobenzene 1n the diet was
different 1n that both Smith and Cabral and Arnold used arachls oil and
corn oil as hexachlorobenzene solvents while Lambrecht did not use an
oil vehicle. Absorption characteristics are known to depend upon the
vehicles used.
1874A 12-90 04/16/84
-------
5. The Sprague-Dawley animals used by Arnold may have more fat than those
used by Lambrecht as they were somewhat larger. Distribution Into
different tissue compartments, especially Into fat where 1t 1s likely
the hexachlorobenzene 1s at least temporarily stored, Is likely to alter
the effective concentration 1n target tissues. In this regard the hexa-
chlorobenzene 1s known to concentrate 1n adrenal tissue; the degree of
such concentration may well vary with strain or diet of the host animals.
In summary, orally administered hexachlorobenzene has Induced hepato-
cellular carcinoma 1n male Sprague-Dawley (S-D) rats as well as hepatomas 1n
female Agus and Wlstar rats and 1n S-D rats of both sexes. At the lowest
dose used 1n any of the studies (40 ppm In the diet or 1.5 mg/kg/day), neo-
plastlc nodules were Induced 1n S-D rats, whereas hepatocellular carcinomas
occurred 1n the same strain at a higher dose (4-5 mg/kg/day). Adrenal pheo-
chromocytoma was significantly elevated 1n two separate studies 1n female
S-D rats. In the same strain one Investigator reported parathyroid tumors
and a different Investigator reported kidney tumors; neither of these
findings has been repeated by other authors. Table 12-30 summarizes this
Information.
12.3.5.5. OTHER STUDIES — In addition to the studies described on
hamsters, mice and rats there are a few studies which cover specific kinds
of tests other than lifetime exposure and examination of all potential
target tissues for tumorlgenlc or carcinogenic response.
One such study was that of Thelss et al. (1977) 1n which the experiment
was designed to detect only pulmonary tumors following 1.p. Injection of
organic chemicals found as contaminants of drinking water. In this assay
hexachlorobenzene was one of the chemicals tested. Strain A mice were given
three dosage levels of hexachlorobenzene with the top level as the MTD. A
total of 24 Injections over a period of 8 weeks were given to 20 mice/group.
1874A 12-91 03/26/84
-------
00
TABLE 12-30
Qualitative Comparison of Tumor Development 1n Rats Following Hexachlorobenzene Administration 1n Different Studies
Strain/Sex
Agus/Female
^ Hlstar/Female
i
Sprague-Dawley/
Kale and female
Sprague-Dawley/
Male and female
FT animals of
2-generat1on study
Dosage
(lowest dose that
produced tumor)
100 ppm (6-8 mg/kg bw/day)
prepared by dissolving In
oil and mixing oil with food
75 ppm (3-4 mg/kg bw/day)
prepared 1n feed sans oil
vehicle
40 ppm (0.3-1.5 mg/kg bw/day)
prepared 1n oil and mixing
oil with food at weaning --
animals exposed 1n utero and
during nursing
Liver
liver -cell tumor
(F)
liver-cell tumor
(F)
hepatocellular
carcinoma (M&F)
hepatoma (M&F)
neoplastlc liver
nodules (F)
Kidney Adrenal
NA NA
NA NA
renal cell pheochromo-
adenoma (M&F) cytoma (F)
cortical
adenoma (F)
not found pheochronto-
cytoraa (F)
Parathyroid Reference
NA Smith and
Cabral, 1980
NA Smith and
Cabral, 1980
NA Lambrecht,
1983a,b
adenoma (K) Arnold, 1983
NA = It 1s not known whether or not these tissues were examined.
CO
o
CD
-P-
-------
The total doses received were 190, 480 and 960 mg/kg. Lungs were the only
organ examined and hexachlorobenzene did not Increase tumor Incidence 1n
that organ. The study ran for 32 weeks. Although this assay has proved
useful 1n detecting some pulmonary carcinogens, 1t 1s not designed to detect
other tumors.
In another study on beagle dogs 1n which hexachlorobenzene was given 1n
dally gelatin capsules to 30 animals of each sex/dosage group the duration
of the study was only 1 year. Although this 1s not a long enough period of
time for a carc1nogen1c1ty study in dogs, 1t 1s of Interest to note that the
doses of 100, 10, 1 and 0.1 mg/kg bw/day produced a number of toxic mani-
festations 1n the liver Including bile duct hyperplasia, hepatomegaly and
liver necrosis. This study 1s more appropriately considered under chronic
toxldty.
Finally, Perelra et al. (1982) designed a study to determine whether
hexachlorobenzene Increased Y-glutamyltranspept1dase-pos1t1ve foci 1n
rats. These fod are believed to be preneoplastlc 1n the liver. The assay
1s designed to test Initiation/promotion 1n this case by employing dlethyl-
N-n1trosam1ne (DENA) as the Initiating agent and hexachlorobenzene as the
promoter. Unfortunately, there are some errors 1n reporting of the results
1n the published paper and some Important controls were not Included
(Perelra, 1983). We have not yet received a corrected manuscript.
12.3.5.6. QUANTITATIVE ESTIMATION -- Among the six chlorinated ben-
zenes reviewed 1n this document, only hexachlorobenzene provides sufficient
data for a risk estimate. This quantitative section deals with estimation
of the unit risk for hexachlorobenzene as a potential carcinogen 1n air and
water, and with the potency of hexachlorobenzene relative to other carcino-
gens that have been evaluated by the U.S. EPA Carcinogen Assessment Group
1874A 12-93 04/19/84
-------
(CAG). The unit risk for an air or water pollutant 1s defined as the
lifetime cancer risk to humans from dally exposure to a concentration of
1 yg/m3 of the pollutant 1n air by Inhalation, or to a concentration of
1 pg/8. 1n water by Ingestlon.
The unit risk estimate for hexachlorobenzene represents an extrapolation
below the dose range of experimental data. There 1s currently no solid
scientific basis for any mathematical extrapolation model that relates expo-
sure to cancer risk at the extremely low concentrations, Including the unit
concentration given above, that must be dealt with 1n evaluating environ-
mental hazards. For practical reasons the correspondingly low levels of
risk cannot be measured directly either by animal experiments or by eplde-
mlologlc study. Low dose extrapolation must, therefore, be based on current
understanding of the mechanisms of cardnogenesls. At the present time the
dominant view of the carcinogenic process Involves the concept that most
cancer-causing agents also cause Irreversible damage to DNA. This position
1s based In part on the fact that a very large proportion of agents that
cause cancer are also mutagenlc. There 1s reason to expect that the quantal
response that Is characteristic of mutagenesls 1s associated with a linear
(at low doses) non-threshold dose-response relationship. Indeed, there 1s
substantial evidence from mutagenldty studies with both Ionizing radiation
and a wide variety of chemicals that this type of dose-response model 1s 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 mutagenlc
response. The linear non-threshold dose-response relationship Is also
consistent with the relatively few ep1dem1olog1c studies of cancer responses
to specific agents that contain enough Information to make the evaluation
1874A 12-94 03/30/84
-------
possible (e.g., radiation-Induced leukemia, breast and thyroid cancer, skin
cancer Induced by arsenic 1n drinking water, liver cancer Induced by
aflatoxlns 1n the diet). Some supporting evidence also exists from animal
experiments (e.g., the Initiation stage of the two-stage cardnogenesls
model 1n rat liver and mouse skin).
Because Us scientific basis, although limited, 1s the best of any of
the current mathematical extrapolation models, the non-threshold model,
which 1s linear at low doses, has been adopted as the primary basis for risk
extrapolation to low levels of the dose-response relationship. The risk
estimates made with such a model should be regarded as conservative, repre-
senting the most plausible upper limit for the risk (I.e., the true risk 1s
not likely to be higher than the estimate, but 1t could be lower).
For several reasons, the unit risk estimate based on animal bloassays 1s
only an approximate Indication of the absolute risk 1n populations exposed
to known carcinogen concentrations. First, there are Important species
differences 1n uptake, metabolism and organ distribution of carcinogens, as
well as species differences 1n target site susceptibility, 1mmunolog1cal
responses, hormone function, dietary factors and disease. Second, the con-
cept of equivalent doses for humans compared to animals on a mg/surface area
basis 1s virtually without experimental verification as regards carcinogenic
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 1n
which the test species, strain, sex and routes of exposure are similar.
1874A 12-95 03/26/84
-------
The quantitative aspect of carcinogen risk assessment 1s addressed here
because of Us possible value 1n the regulatory decision-making process,
e.g., 1n setting regulatory priorities, evaluating the adequacy of technol-
ogy-based controls, etc. 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 here
provides a rough but plausible estimate of the upper limit of risk - that
1s, with this model 1t 1s not likely that the true risk would be much more
than the estimated risk, but 1t could be considerably lower. The risk esti-
mates presented 1n subsequent sections should not be regarded, therefore, as
accurate representations of the 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 1s found to be useful.
12.3.5.6.1. Procedures for the Determination of Unit Risk —
12.3.5.6.1.1. Low Dose Extrapolation Model. The mathematical formula-
tion chosen to describe the linear non-threshold dose-response relationship
at low doses 1s the linearized multistage model. This model employs enough
arbitrary constants to be able to fit almost any monotonlcally Increasing
dose-response data, and 1t Incorporates a procedure for estimating the
largest possible linear slope (1n the 95% confidence limit sense) at low
extrapolated doses that 1s consistent with the data at all dose levels of
the experiment.
Let P(d) represent the lifetime risk (probability) of cancer at dose d.
The multistage model has the form
P(d) = 1 - exp t-(qQ + q]d + q]d* + ...+ qkdk)]
where
q^ > 0, 1 = 0, 1, 2, .... k
1874A 12-96 03/30/84
-------
Equlvalently,
Pt(d) = 1 - exp [-I
where
Pt(d) =
1 - P(0)
1s the extra risk over background rate at dose d.
The point estimate of the coefficients q,, 1 = 0, 1, 2 k, and
consequently, the extra risk function, Pt(d), at any given dose d, 1s
calculated by maximizing the likelihood function of the data.
The point estimate and the 95% upper confidence limit of the extra risk,
Pt(d), are calculated by using the computer program, GLOBAL79, developed
by Crump and Watson (1979). At low doses, upper 95% confidence limits on
the extra risk and lower 95% confidence limits on the dose producing a given
risk are determined from a 95% upper confidence limit, q * on parameter
q-j. Whenever q1 > 0, at low doses the extra risk Pt(d) has approxi-
mately the form ?t(d) = q^ x d. Therefore, q * x d 1s a 95% upper
confidence limit on the extra risk and R/q * Is a 95% lower confidence
limit on the dose, producing an extra risk of R. Let LQ be the maximum
value of the log-likelihood function. The upper-limit q * 1s calculated
by Increasing q to a value q * such that when the log-likelihood 1s
remaximized subject to this fixed value q * for the linear coefficient,
the resulting maximum value of the log-likelihood L, satisfies the equation
2 (LQ - 1^) = 2.70554
where 2.70554 is the cumulative 90% point of the ch1-square distribution
with one degree of freedom, which corresponds to a 95% upper-limit (one-
sided). This approach of computing the upper confidence limit for the extra
risk P (d) 1s an improvement on the Crump et al. (1977) model. The upper
confidence limit for the extra risk calculated at low doses is always
1874A 12-97 03/26/84
-------
linear. This Is conceptually consistent with the linear non-threshold
concept discussed earlier. The slope, q * 1s taken as an upper-bound of
the potency of the chemical 1n Inducing cancer at low doses. [In the
section calculating the risk estimates, P.(d) will be abbreviated as P.]
In fitting the dose-response model, the number of terms 1n the poly-
nomial 1s chosen equal to (h-1), where h 1s the number of dose groups 1n the
experiment, including the control group.
Whenever the multistage model does not fit the data sufficiently well,
data at the highest dose 1s deleted and the model 1s refit to the rest of
the data. This 1s continued until an acceptable fit to the data is
obtained. To determine whether or not a fit is acceptable, the chi-square
statistic
h
X2 z
"
the
is calculated where N^ is the number of animals 1n the 1 dose group,
the
X. is the number of animals in the 1 dose group with a tumor
the
response, P. 1s the probability of a response in the 1 dose group
estimated by fitting the multistage model to the data, and h 1s the number
of remaining groups. The fit is determined to be unacceptable whenever X2
1s larger than the cumulative 99% point of the chi-square distribution with
f degrees of freedom, where f equals the number of dose groups minus the
number of non-zero multistage coefficients.
12.3.5.6.1.2. 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 1n the model. It may
also be appropriate to correct for metabolism differences between species
1874A 12-98 03/26/84
-------
and for absorption factors via different routes of administration. The
procedures used 1n 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 1s the set where the Incidence 1s 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 carcinogenic risk, q * 1s selected 1n most cases.
However, efforts are made to exclude data sets that produce spuriously
high risk estimates because of a small number of animals. That 1s, 1f
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
1s 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, 1s used for risk
assessment. The geometric mean of numbers A,, A0, ..., A 1s
I i m
defined as
(A-, x A2 x ... x Am) m.
3. If two or more significant tumor sites are observed 1n the same study,
and 1f the data are available, the number of animals with at least one
of the specific tumor sites under consideration 1s used as Incidence
data 1n the model.
1874A 12-99 03/26/84
-------
12.3.5.6.1.3. Calculation of Human Equivalent Dosages. Following the
suggestion of Mantel and Schnelderman (1975), 1t 1s assumed that mg/surface
area/day 1s an equivalent dose between species. Since, to a close approxi-
mation, the surface area 1s proportional to the two-thirds power of the
weight, as would be the case for a perfect sphere, the exposure 1n
2/3
mg/day of the weight 1s also considered to be equivalent exposure. In
an animal experiment, this equivalent dose 1s computed 1n the following
manner.
Let
Le = duration of experiment
le = duration of exposure
m = average dose per day 1n mg during administration of the agent
(I.e., during le), and
W = average weight of the experimental animal
Then, the lifetime exposure 1s
le xm
Le x W2/3
ORAL: Often exposures are not given 1n units of mg/day, and 1t
becomes necessary to convert the given exposures Into mg/day. Similarly, 1n
drinking water studies, exposure 1s expressed as ppm 1n the water. For
example, 1n most feeding studies exposure 1s given 1n terms of ppm 1n the
diet. In these cases, the exposure 1n mg/day 1s
m = ppm x F x r
where ppm 1s parts per million of the carcinogenic agent 1n the diet or
water, F 1s the weight of the food or water consumed per day 1n kg, and r 1s
the absorption fraction. In the absence of any data to the contrary, r 1s
assumed to be equal to one. For a uniform diet, the weight of the food
1874A 12-100 04/16/84
-------
consumed 1s proportional to the calories required, which In turn 1s propor-
tional 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
m a ppm x W x r
or
m
a ppm.
rW2/3
As a result, ppm 1n the diet or water 1s often assumed to be an equivalent
exposure between species. However, this 1s not justified for the present
study, since the ratio of calories to food weight 1s very different 1n the
diet of man as compared to laboratory animals, primarily due to differences
1n the moisture content of the foods eaten. For the same reason, the amount
of drinking water required by each species also differs. It 1s therefore
necessary to use an empirically-derived factor, f = F/W, which 1s the
fraction of an organism's body weight that 1s consumed per day as food,
expressed as follows:
Species
Man
Rats
Mice
W
70
0.35
0.03
Fraction of Body Weight Consumed as
ffood ^water
0.028 0.029
0.05 0.078
0.13 0.17
Thus, when the exposure 1s given as a certain dietary or water concentration
2/3
1n ppm, the exposure 1n mg/W 1s
^ . UULL . ngUUi. „ ,, K
1874A 12-101 03/26/84
-------
When exposure 1s given 1n terms of mg/kg/day = m/Wr = s, the conversion 1s
simply
. s x
rW2/3
INHALATION: When exposure 1s via Inhalation, the calculation of dose
can be considered for two cases where 1) the carcinogenic agent 1s either a
completely water-soluble gas or an aerosol and 1s absorbed proportionally to
the amount of air breathed 1n, and 2) where the carcinogen 1s a poorly
water-soluble gas which reaches an equilibrium between the air breathed and
the body compartments. After equilibrium 1s reached, the rate of absorption
of these agents 1s expected to be proportional to the metabolic rate, which
1n turn 1s proportional to the rate of oxygen consumption, which 1n turn 1s
a function of surface area.
Case 1: Agents that are 1n the form of partlculate matter or virtu-
ally completely absorbed gases, such as sulfur dioxide, can reasonably be
expected to be absorbed proportionally to the breathing rate. In this case
the exposure 1n mg/day may be expressed as
m = I x v x r
where I = Inhalation rate per day 1n m3, v = mg/m3 of the agent 1n 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 Biol-
ogy (FASEB, 1974) that 25 g mice breathe 34.5 I/day and 113 g rats breathe
105 9,/day. For mice and rats of other weights, W (1n kg), the surface
area proportionality can be used to find breathing rates 1n mVday as
follows:
2/3
For mice, I = 0.0345 (W/0.025) mVday
p/3
For rats, I = 0.105 (W/0.113) ' mVday
1874A 12-102 03/26/84
-------
For humans, the value of 20 mVday* 1s adopted as a standard breathing
2/3
rate (ICRP, 1977). The equivalent exposure 1n mg/W for these agents
can be derived from the air Intake data 1n a way analogous to the food
Intake data. The empirical factors for the air Intake/kg/day, 1 = I/W,
based upon the previously stated relationships, are tabulated as follows:
Species H 1 = I/W
Man 70 0.29
Rats 0.35 0.64
Mice 0.03 1.3
Therefore, for partlculates or completely absorbed gases, the equivalent
2/3
exposure 1n mg/W Is
d _ jn_ _ lyr_ _ iwyr _ 1wi/3vr
a " w2/3 ~ w2/3 " w2/3
In the absence of experimental Information or a sound theoretical argu-
ment to the contrary, the fraction absorbed, r, 1s assumed to be the same
for all species.
Case 2: The dose 1n mg/day of partially soluble vapors 1s proportion-
2/3
al to the Op consumption, which 1n turn 1s proportional to W and 1s
also proportional to the solubility of the gas 1n body fluids, which can be
expressed as an absorption coefficient, r, for the gas. Therefore, express-
2/3
1ng the Op consumption as Op = k W , where k 1s a constant Indepen-
dent of species, 1t follows that
= kW xvxr
*From "Recommendation of the International Commission on Radiological Pro-
section", page 9. The average breathing rate 1s 107 cm3 per 8-hour
workday and 2xl07 cm3 1n 24 hours.
1874A 12-103 03/26/84
-------
or
j m i
d = ~^ = kvr
W2/3
As with Case 1, 1n the absence of experimental Information or a sound theo-
retical argument to the contrary, the absorption fraction, r, 1s assumed to
be the same for all species. Therefore, for these substances a certain
concentration 1n ppm or yg/m3 1n experimental animals 1s equivalent to
the same concentration 1n humans. This 1s supported by the observation that
the minimum alveolar concentration necessary to produce a given "stage" of
anesthesia 1s similar 1n man and animals (Drlpps et al., 1977). When the
animals are exposed via the oral route and human exposure 1s via Inhalation
or vice versa, the assumption 1s made, unless there 1s pharmacoklnetlc
evidence to the contrary, that absorption 1s equal by either exposure route.
12.3.5.6.1.4. Calculation of the United Risk from Animal Studies. The
2/3
risk associated with d mg/kg /day 1s 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" 1n units X 1s simply the risk
corresponding to an exposure of X = 1. This value 1s estimated simply by
2/3
finding the number of mg/kg /day that corresponds to one unit of X, and
substituting this value Into the above relationship. Thus, for example, 1f
1 /T
X 1s 1n units of vg/m3 1n the air, then for Case 1, d = 0.29 x 70 x
?/3
10 3 mg/kg /day, and for Case 2, d = 1, when yg/m3 1s the unit
used to compute parameters 1n animal experiments.
If exposures are given 1n terms of ppm 1n air, the following calculation
may be used:
, n molecular weight (gas)
1 ppm = 1.2 x — mg/m3
molecular weight (air)
1874A 12-104 03/26/84
-------
Note that an equivalent method of calculating unit risk would be to use
the
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.
ADJUSTMENTS FOR LESS THAN LIFESPAN DURATION OF EXPERIMENT: If the
duration of experiment L 1s less than the natural Hfespan of the test
animal L, the slope q,*, or more generally the exponent g(d), 1s Increased
by multiplying a factor (L/L )3. We assume that If the average dose d
1s continued, ths age-specific rate of cancer will continue to Increase as a
constant function of the background rate. The age-specific rates for humans
Increase at least by the third power of the age and often by a considerably
higher power, as demonstrated by Doll (1971). Thus, 1t 1s expected that the
cumulative tumor rate would Increase by at least the third power of age.
Using this fact, 1t 1s 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, 1f the slope q * [or g(d)j 1s calculated at age L , U 1s
expected that 1f the experiment had been continued for the full Hfespan L
at the given average exposure, the slope q * [or g(d)J would have been
Increased by at least (L/L )3.
This adjustment 1s conceptually consistent with the proportional hazard
model proposed by Cox (1972) and the t1me-to-tumor model considered by
Daffer et al. (1980), where the probability of cancer by age t and at dose d
1s given by
P(d.t) = 1 - exp [-f(t) x g(d)].
1874A 12-105 03/26/84
-------
12.3.5.6.2. UnH Risk Estimates --
12.3.5.6.2.1. Data Available for Potency Calculation. Hexachloro-
benzene has been shown to Induce tumors 1n hamsters, mice and rats. The
primary target organ appears to be the liver In all three of these species.
Liver haemang1oendothel1omas 1n hamsters and hepatocellular carcinomas 1n
rats were significantly Increased 1n the hexachlorobenzene-treated animals.
The potency estimate calculated on the basis of hepatocellular carcinomas 1n
female rats 1s used to derive unit risk estimates for hexachlorobenzene 1n
air and water. This particular tumor site 1s selected for calculating unit
risks because 1t 1s a malignant tumor 1n the primary target organ and
results 1n the highest potency estimate.
Increased Incidences of thyroid, parathyroid, adrenal and kidney tumors
were also observed among these species. Fourteen data sets showing signifi-
cant tumor Incidences have been used herein to calculate the carcinogenic
potency of hexachlorobenzene. These calculations provide a range of esti-
mates that, In part, reflect the uncertainties Inherent 1n the risk assess-
ment process. Tables 12-31 through 12-34 summarize the data used to calcu-
late the potency of hexachlorobenzene. These data have been discussed and
evaluated elsewhere 1n this chapter.
12.3.5.6.2.2. Choice of Low-Dose Extrapolation. In addition to the
multistage model currently used by CA6 for low-dose extrapolation, CA6 also
uses three other models, the probH, the Welbull and the one-hit models, to
estimate the risks from exposure to hexachlorobenzene using the data for
hepatocellular carcinoma 1n female rats. These models cover almost the
entire spectrum of risk estimates that could be generated from the existing
mathematical extrapolation models. These models are generally statistical
1n character, and are not derived from biological arguments, except for the
1874A 12-106 04/16/84
-------
TABLE 12-31
Tumor Incidences 1n Male and Female Hamsters Given
Hexachlorobenzene 1n Diet3
Doseb
(mg/kg/day)
0
4
9
16
Thyroid
Male
0/40
0/30
1/30
8/57
Hepatoma
Male
0/40
14/30
26/30
49/57
Female
0/30
14/30
17/30
51/60
Liver Hemang1oendothel1oma
Male
0/40
1/30
6/30
20/57
F ema 1 e
0/39
0/30
2/30
7/60
aSource: Cabral et al., 1977
blf mg/surface area/day 1s assumed to be equivalent between humans and
animals, the dose 1n mg/kg/day 1s multiplied by a factor (0.1/70)1/3,
where 70 and 0.1 kg are, respectively, the average body weights of humans
and hamsters.
1874A
12-107
03/26/84
-------
TABLE 12-32
Incidence of Liver Cell Tumors 1n Male and Female Swiss Mice
Given Hexachlorobenzene D1eta
Doseb Malec Femalec
(mg/kg/day)
0 0/47 0/49
6 0/30 0/30
12 3/12 3/12
24 7/29 14/26
aSource: Cabral et al., 1979
^If the equivalent dose between humans and mice 1s assumed to be on the
basis of bodv surface area, the dose 1n mg/kg/day 1s multiplied by a factor
(0.035/70 )1/3\ where 0.035 kg and 70 kg are, respectively, the average
body weights of mice and humans.
cThe number of animals that survived at the first observed liver cell
tumor 1s used as the denominator.
1874A 12-108 03/26/84
-------
TABLE 12-33
Liver and Kidney Tumor Incidence Rates 1n Male and Female
Sprague-Dawley Rats Given Hexachlorobenzene 1n D1eta
Sex
Male
F ema 1 e
Ooseb
(mg/kg/day)
0
4.24
8.48
0
4.67
9.34
Hepatocellular
Carcinoma
0/54
3/52
4/56
0/52
36/56
48/55
Hepatoma
0/54
10/52
11/56
0/52
26/56
35/55
Renal Cell
Adenoma
7/54
41/52
42/56
1/52
7/56
15/54
aSource: Lambrecht, 1983a,b. Additional data from this study on adrenal
pheochromocytoma has recently become available (Peters et al., 1983, summa-
rized 1n Table 12-26) but was not available when quantitative estimates
were made.
bThe dosages are calculated by the Investigator based on the average food
consumption of 22.6 g/rat/day and an average body weight of 400 g for male
rats. For female rats, the average food consumption 1s 16.5 g/rat/day and
the average body weight 1s 265 g. If the equivalent dose between humans and
mice Is assumed to be on the basis of body surface area, the dose presented
1n the table 1s multiplied by a factor (Wa/70)1/3, where Wa 1s the
body weight of male or female rats, and 70 kg 1s the human body weight.
1874A 12-109 03/26/84
-------
TABLE 12-34
Incidence Rate of Adrenal Pheochromocytoma 1n Female Sprague-Dawley
Rats (FI generation) 1n a 2-Generat1on Feeding Study
Dose3
(mg/kg/day)
0
0.02
0.08
0.40
1.90
Incidence Rateb
(used 1n calculations)
2/48
4/50
4/50
5/49
17/49
Revised Incidence Ratec
2/49
4/49
4/49
alf the equivalent dose between humans and rats 1s assumed to be on the
basis of body surface, the dose 1n this table 1s multiplied by a factor
(0.35/70)1/3, where 70 kg and 0.35 kg are, respectively, assumed to be
the body weight of humans and rats.
bSource: Arnold et al., 1983
cSource: Arnold, 1984. The amended 1984 data are presented 1n Table
12-28, but were not available when quantitative estimates were made.
1874A 12-110 03/30/84
-------
multistage model which has been used to support the somatic mutation
hypothesis of carclnogenesls (Armltage and Doll, 1954; Whlttemore, 1978;
WhUtemore and Keller, 1978). The main differences among these models 1s
the rate at which the response function, P(d), approaches zero or P(0) as
dose, d, decreases. For Instance, the probH model would usually predict a
smaller risk at low doses than the multistage model because of the differ-
ence of the decreasing rate 1n the low-dose region. However, 1t should be
noted that one could always artificially give the multistage model the same
(or even greater) rate of decrease as the problt model by making some dose
transformation and/or by assuming that some of the parameters 1n the multi-
stage model are zero. This, of course, 1s not reasonable without knowing, a
priori, what the carcinogenic process for the agent 1s. Although the multi-
stage model appears to be the most reasonable or at least the most general
model to use, the point estimate generated from this model 1s of limited
value because 1t does not help to determine the shape of the dose-response
curve beyond experimental exposure levels, furthermore, point estimates at
low doses extrapolated beyond experimental doses could be extremely unstable
and could differ drastically, depending on the amount of the lowest experi-
mental dose. Since upper-bound estimates from the multistage model at low
doses are relatively more stable than point estimates, 1t 1s suggested that
the upper-bound estimate for the risk (or the lower-bound estimate for the
dose) be used 1n evaluating the carcinogenic potency of a suspect carcino-
gen. The upper-bound estimate can be taken as a plausible estimate 1f the
true dose-response curve 1s actually linear at low doses. The upper-bound
estimate means that the risks are not likely to be higher, but could be
lower 1f the compound has a concave upward dose-response curve or a thresh-
old at low doses. Another reason one can, at best, obtain an upper-bound
1874A 12-111 03/26/84
-------
estimate of the risk when animal data are used 1s that the estimated risk 1s
a probability conditional to the assumption that an animal carcinogen 1s
also a human carcinogen. Therefore, 1n reality, the actual risk could range
from a value near zero to an upper-bound estimate.
12.3.5.6.2.3. Calculation of the Carcinogenic Potency of Hexachloroben-
zene. Fourteen sets of tumor Incidences which show significant Increases
(see Tables 12-31 through 12-34) are used herein to calculate the carcino-
genic potency of hexachlorobenzene. Since preparing these calculations
additional data from the Lambrecht et al. (1983a,b) study (adrenal pheo-
chromocytoma) and from the Arnold et al. (1983) study (neoplastlc liver
nodules) have become available. Quantitative estimates have not been made
using this data. Using the multistage model for low-dose extrapolation, as
shown 1n Table 12-35, the potency estimates calculated on the basis of these
data sets are approximately within an order of magnitude from each other,
with the exception of the thyroid tumor. These potencies provide a range of
estimates that reflects the uncertainties stemming from the differences 1n
species, tumor sites, solvent vehicles and composition of diet. The range
does not reflect uncertainty resulting from the use of different extrapola-
tion models.
To calculate the unit risks of hexachlorobenzene in air and water, CAG
used an estimate of carcinogenic potency based upon the data for hepatocel-
lular carcinoma 1n female rats. For comparison, three additional low-dose
extrapolation models, the problt, the Welbull and the one-hit models, are
also used to provide risk estimates at dose levels 0.01, 0.1 and 1 mg/kg/
day. These results are presented 1n Table 12-36. The maximum likelihood
estimate of the parameters for all four models are presented 1n Table A-l 1n
the Appendix. At 1 mg/kg/day, all four models predict comparable risks.
1874A 12-112 03/30/84
-------
CD
TABLE 12-35
The Carcinogenic Potency3 of Hexachlorobenzene, Calculated on the Basis of 14 Data Sets,b
Using the Linearized Multistage Model
Study
i
_«J
CO
Date Base
Dose 1s Assumed to be
Equivalent on the Basis of
Body Weight
Surface Area
Reference
Hamster
Mice
Thyroid (male)
Hepatoma:
Male
Female
Hemangi oendothel 1 oma :
Male
Female
Liver cell:
Male
Female
9.3 x 10~3
1.9 x 10'1
1.5 x 10'1
3.2 x 10""2
1.1 x 1(T2
1.7 x 10~2
1.4 x 10~2
8.3
1.7
1.3
2.8
1.0
2.1
1.8
x 10~2
x KT1
x KT1
x 10'1
x 10'1
Cabral
et al.. 1977
Cabral
et al., 1979
o
CO
oo
-------
CD
•—J
TABLE 12-35 (cont.)
Study
Date Base
Dose 1s Assumed to be
Equivalent on the Basis of
Body Weight
Surface Area
Reference
Rats
IVJ
I
Rats
2-generat1on
study
Renal cell:
Male
Female
Hepatocellular carcinoma:
Male
Female
Hepatoma:
Male
Female
Adrenal
Pheochromocytoma
(female)
2.5 x 10'1
4.2 x 10~2
1.8 x 10~2
2.7 x 10'1
4.7 x 10"2
1.5 x KT1
2.8 x KT1
1.4
2.6 x KT1
1.0 x
1.7
2.6 x ItT1
9.0 x 10'1
1.6
Lambrecht,
1983
Arnold
et al., 1983
aq-|* (mg/kg/day)"1 1s the 95% upper confidence limit of the linear component 1n the multistage model.
bS1nce preparing these calculations, additional data from Lambrecht et al. (1983a,b) study (adrenal
Pheochromocytoma) and from Arnold et al. (1983) study (neoplastlc liver nodules) has become available.
These data have not been evaluated.
oo
-------
TABLE 12-36
Upper-Bound3 (Point) Estimation of Risk,
Based on Hepatocellular Carcinoma 1n Female Ratsb
Assumption of
Human Equivalent Models
Dose
Risk at Dose Level (mg/kg/day)
0.01
0.1
a95% upper confidence limit
bSource: Lambrecht, 1983
1.00
On the basis of
body weight
On the basis of
surface area
multistage
problt
Welbull
one-hit
multistage
problt
Welbull
one-hit
2.7 x 10~3
(2.2 x 10"a)
3.6 x 10"»
(1.3 x 10~10)
1.2 x 10~2
(2.5 x 10~3)
2.7 x 10~3
(2.2 x 10~3)
1.7 x 10~2
(1.4 x 10'2)
6.2 x 10~s
(4.1 x 10~«)
5.0 x 10~2
(1.3 x 10"a)
1.7 x 10~a
(1.4 x 10~2)
2.7 x 10~2
(2.2 x 10"2)
1.0 x 10~3
(8.9 x 10~5)
8.4 x 10~2
(2.5 x 10~2)
2.7 x 10"2
(2.2 x 10"2)
1.7 x 10"1
(1.3 x 10"1)
1.3 x 10'1
(2.9 x 10~2)
2.9 x 10'1
(1.3 x 10"1)
1.7 x 10"1
(1.3 x 10'1)
2.4 x 10~!
(2.0 x 10~M
3.4 x 10'1
(1.2 x 10"1)
4.3 x 10'1
(2.2 x 10~M
2.4 x 10"1
(2.0 x 10"1)
B.OxlO"1
(7.4 x lO'1)
8.2 x lO'1
(7.5 x 10"1)
8.1 x 10'1
(7.4 x 10~M
S.OxlO"1
(7.4 x 10'1)
1874A
12-115
04/16/84
-------
At lower doses, the multistage model predicts a higher risk than the problt
model, but a lower risk than the Welbull model.
12.3.5.6.2.4. Risk Associated with 1 pg/i of Hexachlorobenzene 1n
Drinking Water. Under the assumption that dally water consumption for a 70
kg person 1s 2 I, the hexachlorobenzene Intake 1n terms of mg/kg/day 1s
d = 2 l x 1 pg/j, x 1CT3 mg/l/70 kg = 2.86 x 10~5 mg/kg/day.
Therefore, the risk from drinking water containing 1 pg/8. of hexachloro-
benzene 1s estimated to be
P = 1.7 x 2.86 x 1(TS = 4.9 x 10~5.
This calculation uses the carcinogenic potency q * = 1.7/(mg/kg/day),
based on the data on hepatocellular carcinomas 1n female rats, assuming that
dose per surface area 1s equivalent between rats and humans. If the equiva-
lent dose 1s assumed to be on the basis of body weight, the unit risk, P,
would be reduced to 7.6xlO~*.
12.3.5.6.2.5. Risk Associated with 1 pg/m8 of Hexachlorobenzene In
A1r. Since no Inhalation study has been performed on hexachlorobenzene,
the risk from Inhalation exposure can only be estimated by using the carci-
nogenic potency, q * = 1.7/(mg/kg/day), as calculated from the dietary
study referred to elsewhere 1n this chapter. The assumption Is made that
the hexachlorobenzene absorption rate 1s the same whether exposure 1s via
the oral or the Inhalation route.
Assuming the volumetric breathing rate of 20 mVday for a 70 kg
person, the rate 1n mg/kg/day corresponding to 1 pg/m3 hexachlorobenzene
1n air is
d = (20 mVday) x (10~3 mg/pg) x (1/70 kg) = 2.86 x 10"" mg/kg/day.
Therefore, the risk due to Inhaling air contaminated with 1 pg/m3 hexa-
chlorobenzene 1s
P = 1.7 x 2.86 x 10~« = 4.9 x 10~«.
1874A 12-116 03/26/84
-------
This estimation 1s based on the assumption that dose per surface area 1s
equivalent between humans and rats. If dose per body weight 1s assumed to
be equivalent, the unit risk would be reduced to 7.6xl(T5.
12.3.5.6.3. Comparison of Potency with Other Compounds -- One of the
uses of quantitative potency estimates 1s to compare the relative potency of
carcinogens. Figure 12-1 Is a histogram representing the frequency distri-
bution of potency Indices for 54 suspect carcinogens evaluated by CAG. The
actual data summarized by the histogram are presented 1n Table 12-37. The
potency Index 1s derived from q *, the 95% upper bound of the linear
component 1n the multistage model, and 1s expressed 1n terms of (mMol/kg/
day)"1. Where no human data were available, animal oral studies were used
1n preference to animal Inhalation studies, since oral studies have consti-
tuted the majority of animal studies.
Based on data concerning hepatocellular carcinomas 1n female rats, the
potency Index for hexachlorobenzene has been calculated as 5xl02. This
figure 1s derived by multiplying the slope q * = 1.7/(mg/kg/day) and the
molecular weight of hexachlorobenzene, 284.4. This places the potency Index
for hexachlorobenzene 1n the second quartlle of the 54 suspect carcinogens
evaluated by CAG.
The ranking of relative potency Indices 1s subject to the uncertainties
Involved 1n comparing a number of potency estimates for different chemicals
based on varying routes of exposure 1n 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 compari-
son of potencies 1f linearity does not exist at the low-dose range, or If
comparison Is to be made at the high-dose range. If the latter 1s the case,
then an Index other than the one calculated above may be more appropriate.
1874A 12-117 03/30/84
-------
20
18
16
14
> 12
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z
UJ
§10
UJ
QC
"" 8
6
4
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0
• 12 x
4th
QUARTILE
3rd
QUARTILE
,+i
2nd
QUARTILE
1 x 1Q+ 4 x 1Q+2 2 x 10
1st
QUARTILE
*3
-2
0
246
LOG OF POTENCY INDEX
8
FIGURE 12-1
Histogram Representing the Frequency Distribution of the Potency Indices
of 54 Suspect Carcinogens Evaluated by the Carcinogen Assessment Group
1874A
12-118
03/26/84
-------
co
TABLE 12-37
Relative Carcinogenic Potencies Among 54 Chemicals Evaluated by the Carcinogen Assessment Group
as Suspect Human Carc1nogensa»b»c
ro
i
vo
o
CO
•*v
ro
03
Compounds
Acrylon1tr1le
Aflatoxln B,
Aldrln
Allyl chloride
Arsenic
B[a]P
Benzene
Benzldene
Beryllium
Cadmium
Carbon tetrachlorlde
Chlordane
Chlorinated ethanes
l,2-D1chloroethane
Hexachloroethane
1 ,1 ,2,2-Tetrachloroethane
1 ,1 ,!-Tr1chloroethane
1 ,1 ,2-Tr1chloroethane
Chloroform
Chromium
Slope
(mg/kg/day)"1
0.24 (W)
2924
11.4
1.19 x 10~2
15 (H)
11.5
5.2 x 10~2 (W)
234 (W)
1.40
6.65 (W)
1.30 x 10"1
1.61
6.9 x 10~2
1.42 x 10~2
0.20
1.6 x 10~3
5.73 x 10"2
7 x 10~2
41 (W)
Molecular
Weight
53.1
312.3
369.4
76.5
149.8
252.3
78
184.2
9
112.4
153.8
409.8
98.9
236.7
167.9
133.4
133.4
119.4
100
Potency
Index
IxlO*1
9x!0*5
4xlO+3
9xl(Ti
2xlO*3
3X10+3
4x10°
4xlO+4
lxlO+1
7xlO*2
2xlO+1
7xlO+2
7x10°
3x10°
3xlO+1
2X10'1
8x10°
8x10°
4xlO+3
Order of
Magnitude
(Iog10 Index)
+1
46
+4
0
43
43
4l
45
4l
43
4l
43
4l
0
4l
-1
4l
4l
44
-------
TABLE 12-37 (cont.)
OS
rvs
o
CO
CO
Compounds
DOT
Dlchlorobenzldlne
1 ,1-Dichloroethylene
Dleldrin
Dlnltrotoluene
D1phenylhydraz1ne
Ep1chlorohydr1n
B1s(2-chloroethyl }ether
B1s(chloromethyl )ether
Ethylene dlbromlde (ECB)
Ethylene oxide
Heptachlor
Hexachlorobenzene
Hexachlorobutadlene
Hexachlorocyclohexane
Technical grade
Alpha Isomer
Beta Isomer
Gamma Isomer
Hexachlorod1benzod1ox1n
Methylene chloride
Nickel
Slope
(mg/kg/day)"1
8.42
1.69
1.47 x 10"1 (I)
30.4
0.31
0.77
9.9 x 10~3
1.14
9300 (I)
8.51
1.26 (I)
3.37
1.67
7.75 x 10~2
4.75
11.12
1.84
1.33
1.1 x 10f4
6.3 x 10~4
1.15 (W)
Molecular
Weight
354.5
253.1
97
380.9
182
180
92.5
143
115
187.9
44.1
373.3
284.4
261
290.9
290.9
290.9
290.9
391
84.9
58.7
Potency
Index
3X10+3
4X1Q+2
lxlO+1
1X10+4
6X10+1
IxlO*2
9X10"1
2xlO*2
lxlO+6
2xlO+3
6X10*1
lxlO+3
5X10+2
2xlO+1
Ixl0t3
3xlO+3
5x10 2
4x10
4xlO+6
5xlO~2
7xlO+1
Order of
Magnitude
(logio Index)
+3
+3
+ 1
+4
+2
+ 2
0
+ 2
+6
+3
+2
+ 3
+3
+1
+3
+ 3
4-3
+7
-1
+ 2
-------
CO
TABLE 12-37 (cont.)
IN3
I
INS
O
CO
ro
CD
-fa.
Compounds
NHrosamlnes
D1methylnHrosam1ne
D1ethyln1trosam1ne
D1butyln1trosam1ne
N-n1trosopyrrol1d1ne
N-nHroso-N-ethylurea
N-n1troso-N-me thy 1 urea
N-n1troso-d1phenylam1ne
PCBs
Phenols
2,4,6-TMchlorophenol
Tetrachlorod1benzo-p-d1ox1n
Tetrachloroethylene
Toxaphene
TMchloroethylene
Vinyl chloride
Slope
(mg/kg/day)"1
25.9 (not by q-|*)
43.5 (not by q-|*)
5.43
2.13
32.9
302.6
4.92 x 10"3
4.34
1.99 x 10~2
1.56 x 10s
3.5 x 1(T2
1.13
1.9 x 10~2
1.75 x 10"2 (I)
Molecular
Weight
74.1
102.1
158.2
100.2
117.1
103.1
198
324
197.4
322
165.8
414
131.4
62.5
Potency
Index
2xlO+3
4xlO+3
9xlO+2
2xlOt2
4xlO+3
3xlO+4
1x10°
IxlO*3
4x10°
5X10+7
6x10°
5xlO+2
2.5x10°
1x10°
Order of
Magnitude
(logic Index)
+3
+4
+3
+2
+4
+4
0
+3
+1
+8
+1
+3
0
0
aAn1mal 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
non-threshold model.
bThe potency Index 1s a rounded-off slope 1n (mMol/kg/day) 3
slopes 1n (mg/kg/day)"1 by the molecular weight of the compound.
and 1s calculated by multiplying the
cNot all of the carcinogenic potencies presented 1n this table represent the same degree of certainty.
All are subject to change as new evidence becomes available.
-------
12.3.5.6.4. Summary of Quantitative Estimation -- Data on hepatocellu-
lar carcinomas 1n female rats have been used to estimate the carcinogenic
potency of hexachlorobenzene and the risks associated with one unit of the
compound 1n drinking water and air. The upper bound cancer risks associated
with 1 yg/S. of hexachlorobenzene In drinking water and 1 pg/m3 of
hexachlorobenzene 1n air are estimated to be 5xlQ~5 and 5xlO~4, respec-
tively. These estimates are calculated on the basis of the assumption that
close per surface area 1s equivalent among species. If the dose 1s assumed
to be equivalent on the basis of body weight, the corresponding risk would
be reduced approximately by a factor of 6. The carcinogenic potencies of
hexachlorobenzene are also estimated on the basis of 13 other data sets,
encompassing different tumor sites and animal species. Except for the case
of thyroid tumors, these potency estimates differ from each other within a
single order of magnitude. The range of the estimates reflects the
uncertainties due to differences In species, tumor sites, solvent vehicles,
composition of diet, etc.
12.3.5.7. CARCINOGENICITY SUMMARY — In a lifetime study of hexa-
chlorobenzene dietary administration to hamsters, hepatoma was Induced 1n
both males and females. The response at a dose of 4-5 mg/kg/day was 47% for
both sexes and controls had no hepatomas. In addition to hepatomas,
hamsters responded to hexachlorobenzene treatment with malignant liver
haemangloendothelloma and thyroid adenoma. The Incidence of haemangloendo-
thelloma was 20% 1n males (versus 0 1n controls) at 8 mg/kg/day and 12% 1n
females (versus 0 1n controls) at 16 mg/kg/day. The thyroid adenoma
occurred at 14% Incidence 1n males treated with 16 mg/kg hexachlorobenzene
(versus 0 1n controls).
1874A 12-122 03/30/84
-------
Liver cell tumors, described as hepatomas, were also produced 1n both
sexes 1n Swiss mice. At 24 mg/kg/day the Incidence was 34X for females and
16% for males and the response showed a dose-dependency not only In the
number of tumor-bearing animals but also 1n the latent period, multiplicity
and size of tumors. In ICR mice, hexachlorobenzene administered concur-
rently with polychlorlnated terphenyl Induced hepatocellular carcinomas.
In rats target organs for hexachlorobenzene-lnduced tumors Included
liver, kidney, adrenal gland and parathyroid gland 1n various studies.
Liver tumors were found 1n three studies which Included three different
strains of rat: Agus (a liver tumor sensitive strain), Wlstar and Sprague-
Oawley rats. These tumors were Induced with doses between 1.5 and 8 mg/kg/
day. The Incidence was as high as 100% 1n Agus rats but lower for the other
strains. Renal cell tumors were found 1n one study on Sprague-Dawley rats.
In two studies on Sprague-Dawley rats, significant Increases 1n adrenal
pheochromocytoma 1n females were found. In one of these studies the Inci-
dence of parathyroid tumors 1n males was significantly Increased as well.
Table 12-38 summarizes the tumor data for hamsters, mice and rats for
hexachlorobenzene experiments.
The data on hexachlorobenzene provide sufficient evidence of the card-
nogenldty and tumor1gen1dty of hexachlorobenzene since there were In-
creased Incidences of malignant tumors of the liver In two species (haeman-
gloendotheHoma 1n hamsters and hepatocellular carcinoma 1n rats) as well as
reports of hepatoma 1n mice, rats and hamsters.
The appearance of thyroid tumors 1n hamsters and adrenal pheochromocyto-
mas and parathyroid tumors 1n rats as a result of hexachlorobenzene exposure
1s particularly Interesting because of the clinical association of adrenal
pheochromocytomas with parathyroid and thyroid tumors 1n humans (Fraumenl,
1874A 12-123 04/16/84
-------
CO
TABLE 12-38
-5*
3*
Significantly Increased Incidence of Tumors in Animals Given Hexachlorobenzene 1n Diet
X Treated/X Control
r\j
i
t\>
.**
03/30/84
Animal
(strain)
Hamsters
Hamsters
Mice
Rats
(S.O.)
Rats
(S.O.)
Rats
(S.O.)
Rats
(Mlstar)
Rats
(Agus)
Rats
(S.O.)
Rats
(S.O.)
Rats
(S.O.)
Rats
(S.D.)
Hamsters
NS = Not stated
Organ
liver
liver
liver
liver
liver
liver
liver
liver
adrenal
adrenal
kidney
parathyroid
thyroid
Tumor
hepatoma
haemangl oendothe 1 1 oma
hepatoma
neoplastlc nodules
hepatoma
hepatocellular
carcinoma
hepatoma
hepatoma
pheochromocytoma
pheochromocytoma
renal cell adenoma
adenoma
adenoma
Males
47/0
20/0
16/0
NS
19/0
NS
NS
NS
79/13
25/4
14/0
Females
47/0
12/0
34/0
20/0
46/0
64/0
67/0
100/0
35/4
91/14
13/2
NS
Lowest Dose
to Produce Tumor
(mg/kg bw/day)
4
8 1n males
16 1n females
24
1.5
4-5
4-5
6-8
6-8
1.5
4-5
4-5
1.5
16
Reference
Cabral. 1977
Cabral, 1977
Cabral, 1979
Arnold, 1983
Lambrecht
et al.. 1983a
Lambrecht
et al., 1983a
Smith and
Cabral, 1980
Smith and
Cabral. 1980
Arnold, 1983,
1984
Peters et al. ,
1983
Lambrecht
et al.. 1983b
Arnold, 1983
Cabral, 1977
-------
1974; H111, 1974), and because follow-up of Individuals 1n Turkey, who were
accidentally exposed to hexachlorobenzene over 25 years ago, shows a marked
elevation 1n thyroid tumors. Only a few of these subjects have had their
thyroid tumors examined h1stolog1cally and the pathology reports are not yet
available.
If the IARC criteria for the classification of carcinogens were used,
this animal evidence would be considered "sufficient." In the absence of
human evidence of carc1nogen1c1ty, hexachlorobenzene would be classed 1n
IARC category 28, meaning that 1t 1s probably carcinogenic 1n humans.
A quantitative estimate of the carcinogenic potency of hexachlorobenzene
and an upper-bound estimate of the risks from continuous human exposures to
1 pg/m3 1n air and 1 pg/J, 1n drinking water were made from data on
the hepatocellular carcinoma response 1n female rats. The upper-bound slope
of the dose-response curve, q *, 1s 1.7/(mg/kg/day), giving a potency
Index which 1s 1n the second quartlle of 54 suspect carcinogens evaluated by
the Carcinogen Assessment Group. The unit risks for air and water exposures
are 4.9xlO~« for 1 yg/m3 1n ambient air and 4.9xlO~5 for 1 yg/8.
1n drinking water. Corresponding estimates from 13 other data sets, encom-
passing different tumor sites and animal species, fall within a factor of 10
of these estimates except for thyroid tumors 1n hamsters, which give esti-
mates of about 1/20 of the potency based on the rat hepatocellular carcinoma
response.
12.3.6. Reproductive and Teratogenlc Effects. Hexachlorobenzene has been
shown to be transported via the placenta Into fetal tissues and to be
present in the milk of nursing dams (see Section 12.1.2.). The NOEL In a
4-generation reproduction study with rats was reported to be 20 ppm of hexa-
chlorobenzene 1n the diet. Pups from treated dams (receiving diets contain-
ing 80 ppm hexachlorobenzene) recovered from elevated liver weights when
1874A 12-125 04/16/84
-------
nursed by foster dams. Hepatomegaly and reduced survival was reported In
kittens from cats receiving 263 ppm of hexachlorobenzene 1n their diets.
Infant rhesus monkeys developed clinical signs of toxldty, but hlstologlc
examination showed only mild effects. Fetal mice from dams treated with 100
mg/kg/day during days 7-16 of gestation exhibited teratogenlc abnormalities.
Results from a 4-generat1on reproduction study with Sprague-Dawley rats
was reported by Grant et al. (1977). Weanling rats, 1n groups of 20 females
and 10 males, were fed diets containing 0, 10, 20, 40, 80, 160, 320 or 640
ug hexachlorobenzene/g and at 100 days of age the F generation was
mated to produce the F, generation. The F, pups were weaned at 21
days, and the FQ rats were rested for 14 days and again mated to produce
the second Utter, Flb animals. The Flb animals were then used to
produce the next generation, and this sequence was followed to the F..
generation. The two highest doses (320 and 640 pg/g) were toxic to the
mothers and resulted 1n 20 and 50% mortality, respectively, before the first
whelping and 25% 1n each high dose group before the second whelping. In
addition, the fertility Index 1n these rats was greatly reduced 1n these two
dose groups and the average Utter size was decreased 1n the F , F
ID c.3.
and F2b generations. The pups exhibited no gross abnormalities, but there
was an Increased number of stillbirths and all pups born alive died within 5
days 1n the 320 and 640 pg/g diet groups.
At the 160 pg/g level, 55% of the pups survived to day 5 but survival
to day 21 was greatly reduced. The number of live births and survival was
normal for the first two generations at the 80 pg/g dietary level, but by
the third generation there were stillbirths and a low degree of postnatal
v1ab1Hlty. In addition, birth and weanling body weights were consistently
less than those of the control group. At 40 pg/g diet only the liver
1874A 12-126 03/26/84
-------
weights of the 21-day-old pups were significantly Increased, while the
kidney, heart and brain weights were not affected. Tissue concentrations of
hexachlorobenzene were dose-related, with body fat having the highest
concentration. The NOEL was reported to be 20 ppm 1n the diet.
The effect of hexachlorobenzene on rat reproduction was also reported by
K1tch1n et al. (1982). Female Sprague-Dawley rats (10 animals/treatment
group) were fed diets containing 0, 60, 80, 100, 120 and 140 pg hexa-
chlorobenzene/g of diet. The females were mated with untreated males after
96 days and then bred a second time 12 days after weaning of the F^a
Utter. Fertility and fecundity of treated females were not affected by
treatment; however, a dose-related 21-day Increase 1n mortality was observed
1n both Utters and the LDcn values were determined to be 100 and 140
DU
pg/g (maternal dietary concentration) for the F and F generation,
la ID
respectively.
Mendoza et al. (1978) studied the effects of hexachlorobenzene on
preweanllng Wlstar rats after a reciprocal transfer between 5 treated and 5
control dams. A significant Increase 1n the liver weight over that of the
control was observed 1n pups nursed by dams fed diets containing 80 pg
hexachlorobenzene/g for 2 weeks before mating until birth, but this effect
did not persist after the treated pups were transferred to a control foster
dam. Similarly, the pups nursed by treated dams had smaller brains, hearts,
kidneys and spleens than the controls, and these organs were larger 1n
treated pups nursed by control dams. The authors concluded that hexachloro-
benzene transmission via the milk had greater effects on the pups than
transmission via the placenta.
Mendoza et al. (1979) placed female Wlstar rats on diets containing 80
pg hexachlorobenzene/g beginning 2 weeks before mating until 35-36 days
1874A 12-127 03/26/84
-------
after weaning. Results Indicated that there were no marked differences 1n
the external appearance, body weight, liver weight, gestation, or neonatal
survival between the hexachlorobenzene treated and control females. In
addition, there were no differences 1n the number of Utters, average number
of pups/Utter, average number of pups at birth and gestation Index.
Hansen et al. (1979) studied the effects of hexachlorobenzene on repro-
duction 1n cats fed contaminated pork cakes for 142 days. These cakes con-
tained 9CH51 yg hexachlorobenzene/g, equivalent to an Intake of 3 mg/day/
cat, and were obtained from gilts fed diets containing 100 yg hexachloro-
benzene/g for 6-8 weeks before slaughter. The positive and untreated
control groups received pork cakes from gilts fed diets that did not contain
hexachlorobenzene, with the positive control group receiving hexachloroben-
zene-splked cakes (263^120 yg/g equivalent to 8.7 mg/day/cat). These
females were mated with untreated males and the resulting kittens did not
receive hexachlorobenzene-contalnlng cakes. Effects on survival were noted
1n kittens born to only those cats receiving hexachlorobenzene-splked cakes
and was apparently due to the kittens being too weak to survive the stress
of weaning. There was a tendency for reduced average Utter sizes and
Increased mortality of nursing kittens, and statistically significant
hepatomegaly and reduction 1n kitten survival at weaning. Treated females
exhibited a net weight loss and Increased susceptibility to disease but no
changes In relative organ weights, hematologlc parameters, or fecal copro-
porphyMn excretion.
Rush et al. (1983) fed adult male and female standard dark minks
(Mustela vision) diets containing 0, 1 or 5 ppm hexachlorobenzene and then
mated the males to the females 1n each of the respective study groups. The
resulting mink kits were fed their parents respective diets after weaning
1874A 12-128 03/26/84
-------
from their mothers. The effects of exposures to hexachlorobenzene In utero
and from nursing milk resulted 1n Increased mortality 1n the hexachloro-
benzene-treated weanlings with mortality 1n the 0, 1 and 5 ppm groups being
8.2, 44.1 and 77.4%, respectively. The surviving kits from all three groups
had no observed alterations 1n whole body, kidney or liver weights and no
observed damage to the kidneys or livers at 17 weeks of age. Induction of
hepatic mixed-function oxldases was observed 1n the surviving hexachloro-
benzene-exposed kits without any observable frank hepatotoxldty.
Bailey et al. (1980) studied the transfer of hexachlorobenzene to three
nursing Infant rhesus monkeys from three lactatlng mothers receiving by
gavage 64 mg/kg/day of hexachlorobenzene suspended 1n methyl cellulose for
60 days. The hexachlorobenzene concentrated 1n the mothers' milk ranged
from 7.51-186 ppm during the dosing schedule. One Infant, by day 22, had
developed symptoms of hypoactlvlty and lethargy which progressed to ataxla
and death 1 week later. Autopsy revealed severely congested lungs. A
second Infant died on day 38 and autopsy revealed a subdural hematoma and
bilateral hemorrhaglc pneumonia. This Indicated that the risk of exposure
to nursing Infants was greater than the risk to their mothers. Blood
(0.42-49.44 ppm) and tissue levels 1n the Infants were higher than 1n their
mothers (0.41-16.16 ppm blood), and the Infants developed clinical symptoms
of toxlclty while the mothers were asymptomatic.
Studies on the placental transfer of hexachlorobenzene 1n Wlstar rats
and New Zealand rabbits did not reveal any apparent adverse effects on fetal
development. The female rats were dosed dally with 5, 10, 20, 40 or 80
mg/kg from day 6-16 of gestation, whereas the rabbits were treated with 0,
0.1, 1.0 or 10 mg/kg from day 1-27 of gestation. The compound was dissolved
1n corn oil and administered by means of a stomach tube (Vllleneuve et al.,
1974; Vllleneuve and H1erl1hy, 1975).
1874A 12-129 03/26/84
-------
Khera (1974) conducted a teratogenlclty study with groups of 7-16 female
Wlstar rats given single oral doses of 0, 10, 20, 40, 60, 80 or 120 mg
hexachlorobenzene/kg suspended 1n corn oil or 0.25% aqueous gum tragacanth
during gestation days 6-21. Maternal toxlclty and reduction 1n fetal
weights resulted from the two higher doses. Maternal toxlclty was charac-
terized by loss 1n body weight, hyperesthesla, tremors and convulsions. A
significant Increase 1n the Incidence of unilateral and bilateral 14th Mb
was observed and was related to the duration of treatment (days 10-13, 6-16
or 6-21 of gestation) and the dose. Sternal defects were observed In only 1
of 4 experiments, which lead the authors to conclude that 1t 1s doubtful
that hexachlorobenzene was the cause of the observed sternal defects. There
were no hexachlorobenzene-related effects on external morphology. Visceral
abnormalities were not observed, and microscopic examinations did not reveal
any treatment-related change 1n the histology of the fetuses. Values for
live and dead fetuses, resorptlon sites, and fetal weight were within the
control limits.
Courtney et al. (1976) studied the effects of 1ngest1on of 100 mg/kg/day
hexachlorobenzene on days 7-16 of gestation 1n 10 pregnant CD-I mice. This
study was undertaken to evaluate the possibility that hexachlorobenzene
could be responsible for fetal malformations seen In pregnant animals
exposed to hexachlorobenzene-contamlnated pentachloronltrobenzene. The
results showed that the hexachlorobenzene-treated mice had significantly
Increased maternal I1ver-to-body weight ratios and decreased fetal body
weights. Also, a significant Increase 1n the Incidence of abnormal fetuses
per Utter were observed as compared to control mice. The abnormalities
that were observed 1n these affected fetuses were cleft palates, one
straight leg, small kidneys, one renal agenesis, and enlarged renal pelvis.
1874A 12-130 03/30/84
-------
They concluded from this study that the teratogenlc activity of contaminated
pentachloronltrobenzene was probably due to hexachlorobenzene.
12.4. INTERACTIONS
Certain chemicals have been shown to alter the toxldty and pharmaco-
klnetlcs of hexachlorobenzene 1n mammals. Pentachlorophenol and Iron
Increased the porphyrlnogenlc effect of hexachlorobenzene, whereas
decachloroblphenyl had no effect. Hexachlorobenzene pretreatment resulted
In Increased CC1 toxldty and altered Immune responses In hexachloro-
benzene-treated animals. In addition, hexachlorobenzene has been shown to
Induce hepatic xenoblotlc metabolism and thus has the potential to alter the
rate of metabolism of other chemicals (see Section 12.3.1.).
Debets et al. (1980b) studied the effect of pentachlorophenol (PCP) on
*
hexachlorobenzene toxldty. Groups of female rats were fed diets containing
1000 pg hexachlorobenzene/g, 500 pg pentachlorophenol/g, or both chemi-
cals 1n the same amounts, and a fourth group served as the control. Penta-
chlorophenol accelerated the onset of hexachlorobenzene-lnduced porphyrla,
as Indicated by an Increase 1n urinary excretion of uroporphyMn and a
decrease of porphyrlns with two and three carboxyllc groups. This Increase
occurred ~3 weeks earlier 1n the hexachlorobenzene plus pentachlorophenol-
treated animals than 1n hexachlorobenzene-treated animals.
Razzard1n1 and Smith (1982) Investigated dlethylstHboestrol (DES) pre-
treatment on hexachlorobenzene metabolite excretion 1n young male and female
F344/N rats. The rats were Injected 1.p. with four doses of DES dlproplo-
nate 20 pmoles/kg dissolved 1n arachls oil over a 24-day period and then
given 14 mg/kg hexachlorobenzene by oral Intubation for 7 days. The results
Indicated that the DES pretreatment stimulated the excretion, via urine and
feces, 1n both males and females (Table 12-39).
1874A 12-131 03/26/84
-------
- TABLE 12-39
CXI
~J
> Analysis of the Excreta from Rats Administered Hexachlorobenzene
After an Initial Treatment with D1ethylst1lboestrola«b
Sex and Treatment
Urine
Male + oil
Male + DES
Female + oil
Female + DES
Feces
Male + oil
Male + DES
Female + oil
Female + DES
Pentachlorophenol
151 + 19
190 + 22
174 + 17
453 + 105f
85 + 15
160 + 23f
116 + 35
279 + 80
Tetrachlorobenzene-1 ,4-d1ol
(nmole/24 hours/kg bw)
3 + 1
17 + 2C
16 + 2d
35 + 9
Trace
Trace
Trace
Trace
Pentachlorothlophenol
23 + 3
158 + 9C
142 + 12e
176 + 7f
74 + 23
166 + 33
65 + 4
149 + 13C
co
PO
aSource: Razzard1n1a and Smith, 1982
bMale and female rats (52-54 and 71-73 days old, respectively) were given 20 ymole of DES dlproplo-
nate/kg dissolved 1n arachls oil (10 mg/ma) or oil alone by 1.p. Injection on days 1, 4, 14 and 24.
From day 25 all rats were given 14 mg of hexachlorobenzene/kg by oral Intubation dally for 7 days. After
the last dose 24-hour samples of urine and feces were collected, hydrolyzed and analyzed. Results are
means +_S.E.M. (n=4/group).
Significance of differences from rats not given DES, p<0.001
Significance of differences from males, p<0.005
S GS1gn1f1cance of differences from males, p<0.001
£ fS1gn1fIcance of differences from rats not given DES, p<0.05
* Total excretions of these metabolites were: male, 336+57; male + DES, 691+.70 (p<0.01); female, 513+.62;
female + DES, 1092+175 (p<0.025) nmole/24 hours/kg
-------
Blekkenhorst et al. (1980) reported that the simultaneous l.m. adminis-
tration of Iron and hexachlorobenzene caused a marked potentlatlon of hexa-
chlorobenzene porphyrlnogenlc effect 1n rats. This was shown by a decrease
1n hepatic uroporphyrlnogen decarboxylase activity and Increased urinary and
fecal porphyrln excretion. Conversely, simultaneous bleeding of hexachloro-
benzene-treated rats diminished the porphyrlnogenlc effect of hexachloro-
benzene.
Goldstein et al. (1978) studied the comparative toxlclty of pure hexa-
chlorobenzene (purity >99%) and technical hexachlorobenzene (purity 92X)
which contained 200 ppm of decachloroblphenyl and 4 ppm of octachlorodl-
benzofuran, 1n female CD rats fed diets containing 0, 30, 100, 300 or 1000
Pg hexachlorobenzene/g for up to 15 weeks. Neither grade contained other
chlorinated dlbenzofurans or d1benzo-p-d1ox1ns. Both grades resulted 1n
comparable effects (porphyrla, cutaneous lesions, hyperexc1tab1l1ty, changes
1n liver enzymes and morphological liver changes) 1n treated rats, although
the technical grade appeared to be slightly more potent than pure hexa-
chlorobenzene 1n Us effects on the pulmonary endothellum. The Impurities
did not appear to have a synerglstlc effect.
Kluwe et al. (1982) reported that pretreatment of male Sprague-Oawley
rats with hexachlorobenzene resulted 1n Increased CC1 toxlclty. The rats
received seven doses of hexachlorobenzene at 30 mg/kg once every 72 hours
followed by an 1.p. Injection of CC1 at 0.0, 0.03, 0.05, 0.25, 1.0 or 2.0
mfc/kg 24 hours after the last hexachlorobenzene treatment. Hexachloro-
benzene pretreatment Increased the CC1 .-Induced acute growth retardation,
renal tubular functional Impairment, hepatocellular necrosis and further
reduced the survival of the animals. Variable results were reported In a
study on the effect of hexachlorobenzene pretreatment of male albino
1874A 12-133 03/26/84
-------
Sprague-Oawley rats on the In vivo blotransformatlon, residue deposition,
and elimination of 14C-alddn, 1-naphthol, DDT, hexachlorobenzene or mlrex
(Clark et al., 1981a). There was no evidence of qualitative changes In the
blotransformatlon of any test compound that could be attributed to hexa-
chlorobenzene pretreatment. Analysis of residue deposition gave mixed
results: less 14C residues were found 1n rats fed diets containing hexa-
chlorobenzene and then treated with 14C-aldMn, more 14C residues were
found after 14C-DDT or l4C-m1rex treatment, and no difference was
evident after 14C-hexachlorobenzene or 14C-l-naphthol treatment. Hexa-
chlorobenzene also potentiates the effects of stress on male Sprague-Dawley
rats (Clark et al., 1981). Rats fed 250 ppm hexachlorobenzene resulted 1n
an Increased severe loss of body weight when placed Into crowded cages and
compared to the weight loss of crowded control rats. Crowded rats fed
hexachlorobenzene had higher tissue residues of hexachlorobenzene and higher
mortality than the non-crowded hexachlorobenzene-treated rats or the control
rats.
12.5. SUMMARY
The acute oral toxldty of hexachlorobenzene has been found to be low,
with LD values ranging from 1700-10,000 mg/kg. Subchronlc oral toxldty
studies with a number of mammalian species Indicated a significant Increase
1n liver and kidney weights 1n hexachlorobenzene-treated animals. Studies
have shown Increases 1n other organs as well. The livers from hexachloro-
benzene-exposed animals have shown hlstologlc changes such as Irregular
shaped and moderately enlarged liver mitochondria and Increases 1n the size
of the centrllobular hepatocytes. Chronic oral toxldty studies revealed
the same type of effects seen 1n the subchronlc studies plus hexachloroben-
zene-assodated life-shortening and various hepatic and renal pathologies.
1874A 12-134 03/26/84
-------
These subchronlc and chronic effects were usually dose-related. Other
effects Included multiple alopecia and scabbing, together with neurologic
effects 1n rats, mice and dogs. A dose-related hlstopathologlc change In
the ovaries of monkeys has also been reported.
/
Increased porphyrln levels 1n the liver and 1n urine have been reported
for all species studied except the dog, which does not exhibit Increased
porphyrln levels. Hexachlorobenzene was found to cause the accumulation of
0-H-stero1ds which Induce porphyrln biosynthesis and to Inhibit uroporphy-
rlnogen decarboxylases. The Inhibition of uroporphyrlnogen decarboxylases
appears to be due to pentachlorophenol, a hexachlorobenzene metabolite.
Indications are that females are more susceptible to hexachlorobenzene-
Induced porphyrla than are males, which may be related to the female estro-
gen levels and greater hexachlorobenzene metabolism. Hexachlorobenzene was
reported to produce a mixed-type Induction of cytochromes resembling that
produced by a combination of phenobarbltal (P-450) and 3,4-benzpyrene
(P-448). In addition, the activities of several hepatic mlcrosomal enzymes
were found to be Induced by hexachlorobenzene.
Hexachlorobenzene did not Induce dominant lethal mutations 1n two
studies but was reported to be mutagenlc 1n a yeast, S^ cerevlslae, assay at
a concentration of 100 ppm. Hexachlorobenzene possessed no detectable
levels of mutagenlc activity 1n the Salmonella h1st1d1ne reversion assay.
The chronic toxldty studies provide sufficient evidence of the cardno-
genldty of hexachlorobenzene 1n animals since there was an Increased Inci-
dence of malignant tumors of the liver 1n two species, haemang1oendothel1oma
1n hamsters and hepatocellular carcinoma 1n rats as well as confirmed
reports of hepatoma 1n both of these species. Hexachlorobenzene was found
1874A 12-135 03/26/84
-------
to cause teratogenlc effects 1n fetal mice whose mothers were Ingesting 100
mg/kg/day of hexachlorobenzene during days 7-16 of gestation. Certain
chemicals were found to alter the toxldty of hexachlorobenzene 1n mammals,
whereas hexachlorobenzene pretreatment was reported to Increase CC1.
4
toxldty and alter the Immune responses of treated animals.
1874A 12-136 03/26/84
-------
13. OVERVIEW OF EFFECTS OF MAJOR CONCERN
A primary factor 1n Identifying the major effects of concern resulting
from exposure to the chlorinated benzenes 1s the extent and adequacy of the
available studies on mammalian and human toxicology. As Indicated 1n the
section on research needs (see Section 2.3.), several areas related to the
toxldty of these chemicals have not been Investigated. Except for hexa-
chlorobenzene, few studies have been performed on the carcinogenic, repro-
ductive and teratogenlc toxldty of chlorinated benzenes. However, data are
available on the subchronlc toxic effects produced by the oral and Inhala-
tion routes of exposure for most of the chlorinated benzenes 1n several
species. Studies that provide adequate data on the consequences of chronic
exposure or reproductive and teratologlc effects of particular chlorinated
benzenes do exist, but are more limited 1n number. The absence of discus-
sion or presentation of data on a particular chlorinated benzene should not
be equated with an absence of effects or diminished need for concern; more
likely, 1t reflects a lack of adequate Investigation.
13.1. PRINCIPAL EFFECTS AND TARGET ORGANS
The data available for Identifying the principal effects and sites of
toxldty for the chlorinated benzenes are derived mainly from studies of
subchronlc toxldty, reproductive and teratogenlc effects, and reports of
effects on humans accidentally or occupatlonally exposed to chlorinated
benzenes. In general, the main sites affected by short-term, high-level
exposures are the hepatic, renal and nervous systems. Inhalation and oral
toxldty studies 1n several spedes Indicate that chlorinated benzenes are
capable of Inducing hepatic and renal degeneration and necrosis, disrupting
porphyrln metabolism, and depressing the short-term functioning of the
nervous system. Levels of exposure below those causing hepatic and renal
1836A 13-1 3/26/84
-------
tox1c1ty for some of the chlorinated benzenes have adverse effects on the
long-term functioning of the nervous system and on the hematopoletlc system.
In several studies, the administration of two of the chlorinated benzenes,
penta- and hexachlorobenzene, during gestation 1n rats resulted 1n Increased
fetotoxldty, postnatal mortality and Incidence of fetal skeletal malforma-
tions. Studies 1n rodents have also shown hexachlorobenzene to be a
carcinogen.
Monochlorobenzene, when administered to rats, rabbits and dogs at
moderate to high doses by Inhalation or oral routes caused hepatic and renal
toxldty manifested by Increased liver and kidney weights, hlstopathologlc
changes, elevated serum enzymes, and liver and kidney necrosis (Monsanto
1967a,b; Irish, 1963; Khanln, 1969; Dllley, 1977). At high doses, dogs
developed depression of bone marrow activity (Monsanto 1967a, 1978). Con-
tinuous exposure by Inhalation at low doses disturbed the proper chronaxy
correlation of the muscle antagonists and Increased blood chollnesterase 1n
rats (Tarkhova, 1965). Humans exposed occupatlonally to monochlorobenzene
Intermittently for up to 2 years displayed signs of neurotoxldty Including
numbness, cyanosis, hyperesthesla and muscle spasms (Rozenbaum, 1947).
Subchronlc administration of dlchlorobenzenes by Inhalation to rats,
rabbits and guinea pigs caused liver and kidney toxldty and pulmonary
congestion (HolUngsworth et al., 1956). Oral administration produced
hepatic porphyrla, pathologic changes 1n the kidneys and liver, and Inhibi-
tion of erythropolesls and bone marrow activity (R1m1ngton and Zlegler,
1963; HolUngsworth et al., 1956; Varashavskaya, 1976a,b). Chronic adminis-
tration of 1,2-d1chlorobenzene by gavage to rats and mice at less than
maximum tolerated doses did not produce statistically significant changes 1n
tumor Incidences (NTP, 1982). Case studies of human exposures report a
1836A 13-2 3/26/84
-------
range of effects Including liver necrosis, depression of erythropolesls and
leukemia. A study of 26 persons exposed to 1,2-d1chlorobenzene for 4 work
days reported Increased chromosomal aberrations 1n peripheral leukocytes
(Zapata-Gayon et al., 1982).
Studies of the subchronlc Inhalation toxlclty of 1,2,4-trlchlorobenzene
have Identified hepatic porphyrla and cellular degeneration as effects 1n
rats but not 1n rabbits or monkeys (Coate et al., 1977; Watanabe et al.,
1978). Porphyrla was also Induced 1n rats after the dietary adminis-
tration of high doses of 1,2,3- or 1,2,4-tr1chlorobenzene for 7 days
(R1m1ngton and Zlegler, 1963). Three studies using dermal applications of
1,2,4-trlchlorobenzene or a mixture of 1,2,4- and 1,2,3-tMchlorobenzene to
rabbits and guinea pigs reported skin Irritation at doses as low as 30
mg/kg/day and some systemic toxlclty at higher doses (Brown et al., 1969;
Powers et al., 1975; Rao et al., 1982). In a reproductive study 1n rats,
25, 100 or 400 ppm of 1,2,3-tr1chlorobenzene administered to the parental
animals 1n their drinking water produced no reproductive, hematologlc or
neurologic effects (Robinson et al., 1981). Adrenal enlargement occurred 1n
both the parents and offspring at the highest dose level. In a 2-year mouse
skin painting study (Yamamoto et al., 1957) a slight Increase In tumors of
all sites was reported, but no conclusions can be drawn about carclnogenlc-
1ty because of the lack of details 1n the English translation of the text.
More limited data were available on the toxlclty of the tetrachloroben-
zenes. A single oral subchronlc study with 1,2,4,5-tetrachlorobenzene 1n
rabbits Indicated effects on blood chemistry and hematology at low doses
(Fomenko, 1965); a chronic study with the same Isomers In dogs suggested
adverse effects on liver metabolism (Braun et al., 1978). In a study of
1836A 13-3 04/16/84
-------
workers exposed to 1,2,4,5-tetrachlorobenzene found an Increased Incidence
of chromosomal abnormalities (decreased chromosome number per cell, poly-
ploldy during mitosis, and chromosomal malformations) 1n the leukocytes of
the workers (Klraly et al., 1979).
Data on the toxldty of pentachlorobenzene were also limited. High
levels 1n the diets of rats caused Increased excretion of porphyrlns (Goerz
et al., 1978) and Induced hlstopathologlc changes 1n the kidneys and liver
(Under et al., 1980). Studies of the reproductive and teratologlc effects
of pentachlorobenzene 1n rats Indicated that the chemical Increased fetal
deaths, reduced postnatal survival of pups and Increased the Incidence of
extra ribs and sternal defects (Under et al., 1980; Khera and Vllleneuve,
1975). Teratogenlc effects were not seen 1n mice (Courtney et al., 1979).
The toxldty of long-term dietary exposure of humans to hexachloroben-
zene was demonstrated by the epidemic of porphyMa cutanea tarda (PCT) 1n
Turkish citizens who accidentally consumed bread made from grain treated
with hexachlorobenzene (Cam, 1963; Peters et al., 1966; Peters et al.,
1982). In addition to the PCT-assodated symptoms of skin lesions, hyper-
trlchosls, and hyperpigmentatlon, the exposure caused neurotoxldty and
liver damage, follow-up studies reported PCT symptoms, reduced growth, and
arthritic changes 1n the appendages of children who were directly or
Indirectly (I.e., through breast milk) exposed. Studies 1n rats have demon-
strated hexachlorobenzenes ability to Increase the Incidence of stillbirths,
decrease fetal growth and decrease postnatal survival (Grant et al., 1977;
Khera, 1974). A study 1n rats reported that administration of hexachloro-
benzene during gestation Increased significantly the number of fetuses with
extra ribs. A study 1n mice found that hexachlorobenzene given on days 7-16
of gestation resulted 1n an Increased Incidence of fetal abnormalities when
compared to controls (Courtney et al., 1976). Hexachlorobenzene has been
1B36A 13-4 03/30/84
-------
shown to produce tumors 1n animals. Lifetime dietary administration of hex-
achlorobenzene to hamsters, rats and mice Increased the Incidence of thyroid
tumors 1n hamsters (Cabral et al., 1977), liver tumors 1n hamsters (Cabral
et al., 1977), mice (Cabral et al., 1979) and rats (Smith and Cabral, 1980;
Lambrecht, 1983; Arnold, 1984), kidney tumors 1n rats (Lambrecht, 1983) and
adrenal tumors 1n rats (Arnold, 1983; Peters et al., 1983).
13.2. ANIMAL TOXICITY STUDIES USEFUL FOR HEALTH ASSESSMENT AND ESTIMATED
TOXICITY THRESHOLDS
13.2.1. Animal Toxldty Studies. The studies useful for health assessment
determinations of each of the chlorinated benzenes 1s presented 1n the res-
pective dose/effect Tables 13-1 through 13-7, extracted from the Mammalian
Toxldty Sections of Chapters 7-12 of this document. These tables should
provide assistance 1n selecting the most useful and appropriate studies for
health assessment determinations.
Tables 13-8 through 13-12 attempt to compare a variety of toxic res-
ponses to chlorinated benzenes 1n rats, mice, rabbits, dogs and monkeys.
The recorded values reflect the lowest dosage reported for each listed
effect category for each species, taken from the subchronlc, chronic, car-
c1nogen1dty, reproductive and teratogenldty studies reported In Chapters
7-12 of this document. It should be noted that there 1s the potential for
similar responses 1n each species to occur at lower dose levels than
reported and that a blank entry does not necessarily mean that the effect
does not occur 1n that species Induced by the particular chlorinated
benzene. This 1s probably Indicative of the fact that lower dose levels may
not have been tested and/or that particular effect may not have been speci-
fically looked for by research Investigators. In attempting to use these
tables to determine fine-line conclusions/Interpretations about chlorinated
benzenes structure activity relationships, further complications arise
1836A 13-5 03/30/84
-------
00
oo
TABLE 13-1
Summary of Subchronlc Toxlclty Studies on Monochlorobenzene3
oo
i
00
oo
Species
Dog
(beagle)
Rat
Rat
Rat
Rat
Rat
Rat
Rabbit
Route
Inhalation0
Inhalation
Inhalation
Inhalation
Inhalation
Inhalation
Inhalation
Inhalation
Dose
0.75 mg/l, 6 hrs/day,
5 days/week (162 ppm)
1 .50 mg/l, 6 hrs/day.
5 days/week (424 ppm)
2.00 mg/l, 6 hrs/day,
5 days/week
0.75, 1.50 or 2 mg/l
6 hrs/day, 5 days/week
0.1 or 1.0 mg/m^
(continuous)
0.1 mg/afl (continuous)
1.0 mg/m3 (continuous)
0.1, 1.25 or 1.5 mg/l
0.1 mg/l, 3 hr/day
(alternate days )
75 and 250 ppm, 7 hrs/day
5 days/week
75 and 250 ppm, 7 hrs/day,
5 days/week
Duration
(days)
62
exposures
over 90 days
62
exposures
over 90 days
62
exposures
over 90 days
62
exposures
over 90 days
72-80
60
60
49-98
37 weeks
120
exposures
120
exposures
Effects Reference
None Monsanto, 1978
Weight loss; conjunctivitis; moribund at
31 days
Weight loss; hypoactlvlty and conjunctivitis;
vacuolated hepatocytes; cytoplasmlc vacuolatlon
of renal collecting tubules; bilateral atrophy
of seminiferous tubules; lower total leukocyte
counts, elevated SAP, SGOT, SGPT; aplastlc bone
marrow; mortality In 5/8 dogs after 25-29 days
None Monsanto, 1978
Liver necrosis and regeneration; kidney Khanln, 1977
hyperplasla; encephalopathy; pneumonia
None Tarkhova, 1965
Inhibited chronaxla of antagonistic muscles
at 39 days; Increased blood chollnesterase
ChronaxImetMc Inhibition Plslaru, 1960
Inhibition of extensor Hblalls 7-14 weeks; Gabor and Raucher,
normal by 20 weeks 1960
Focal lesions of adrenal cortex; lesions In Dllley, 1977
tubules of kidneys; congestion of liver and
kidneys; decreased SGOT
Decreased SGOT after 24 weeks of exposure Dllley, 1977
-------
1ABLF 13-1 (cont.
CD
CO
Species
Route
Dose
Duration
(days)
Effects
Reference
Mouse oral (gavage)
60 mg/kg/day, 5 days/week 13 weeks
125 mg/kg/day, 5 days/week 13 weeks
250 mg/kg/day, 5 days/week 13 weeks
500 ing/kg day, 5 days/week 13 weeks
CO
i
Rat
Oral (gavage)
750 mg/kg/day, 5 days/week
60 mg/kg/day, 5 days/week
125 mg/kg/day, 5 days/week
250 mg/kg/day, 5 days/week
500 mg/kg/day, 5 days/week
750 mg/kg day, 5 days/week
PO
\
CO
10 weeks
13 weeks
13 weeks
13 weeks
13 weeks
13 weeks
one male wHh hepatic necrosis NTP, 1983
Increased liver weights 1n males one male
with hepatic necrosis
>50X reduction In weight gain. Increased
excretion of coproporphyrlns In females,
Increased liver weights, lesions of the
liver, kidney, bone marrow, spleen and
thymus
100% lethal to males within 1 week,
reduced body weight gains, polyurla
1n females. Increased liver weights,
lesions of the liver, kidney, bone
marrow, spleen and thymus.
100% lethal to male mice within 1 week
and to female mice within 10 weeks,
lesions of the liver, kidney, bone marrow,
spleen and thymus at death
None NTP, 1983
None
Minimal centrolobular hepatocellular
necrosis
Decreased body weights gain, Increased
GGTP and alkaline phosphatase In females.
Increased excretion of porphyrlns, con-
trolobular hepatocellular necrosis,
nephropathy 1n males, myelold depletion
of bone marrow.
Decreased body weight gain and survival
of animals, hematologlc effects, Increased
GG1P and alkaline phosphatase 1n females,
polyurla 1n males, Increased excretion of
porphyrlns, centrolobular hepatocellular
necrosis, nephropathy, lymphold depletion
of thymus and spleen, myelold depletion of
bone marrow.
-------
oo
CO
01
CO
CD
TABLE 13-1 (cont.)
Species Route
Oog oral (capsule)
Rat oral (diet)
Rat oral (diet)
Dose
27.3 mg/kg/day
54.6 mg/kg/day
272.5 mg/kg/day
12.5 or 50 mg/kg/day
100 mg/kg/day
250 mg/kg/day
14.4 mg/kg/day
144 and 288 mg/kg/day
Duration
(days)
90
90
90
93-99
93-99
93-99
192
192
Effects
None
Diarrhea and vomiting; conjunctivitis
4/8 died In 3-5 weeks; Increased Immature
leukocytes; elevated SGOT and SAP. blllrubln
and cholesterol; low blood sugar; hlstopatho-
loglc changes In liver, kidneys, spleen
None
Increased liver and kidney weights
Increased liver and kidney weights;
retarded growth 1n males
None
Increased liver and kidney weights;
Increased salivation and hair loss
Reference
Monsanto, 1967a
Monsanto, 1967b
Irish, 1963
aSource: Updated from U.S. EPA, 1980a
bl ppm -4.60 mg/m», 1 mg/l -219 ppm (Irish, 1963)
co
co
-------
CD
CO
CT»
CO
I
10
CO
\
f\J
•x
CO
1ABLF 13-2
Subchronlc Toxldty of 1,2-D1chlorobenzene*
Route Concentration
or Dose
Inhalation 560 mg/m>
290 mg/ra'
455 mg/m>
Oral 376 mg/kg (tube)
188 mg/kg (tube)
18.8 mg/kg (tube)
0.01-0.1 nig/kg/day
Regimen
7 hours/day, 5 days/week,
6-7 months
7 hours/day, 5 days/week
6.5 months
dally up to 15 days
5 days/week, 138 doses
5 days/week, 138 doses
5 days/week, 138 doses
5 months
Subject
rat, guinea
t pig, rabbit,
monkey
rat, guinea
pig
rat
rat
rat
rat
rat
Effect
No effect on several parameters
except decreased spleen weights
1n male guinea pigs
No effect on several parameters
Hepatic porphyrla
Liver, kidney weight Increase;
cloudy swelling 1n liver.
Increase In liver and kidney
weight
No effects noted
Hematopoletlc system; altered
Reference
Holllngsworth et al. ,
1958
Holllngsworth et al . ,
1958
R1m1ngton and
Zlegler, 1963
Holllngsworth et al.,
1958
Holllngsworth et al. ,
1958
Holllngsworth et al. ,
1958
Varshavskaya, 1967a
500 mg/kg
5 days/week, 13 weeks
rat
250 mg/kg
125 mg/kg
60 mg/kg
30 mg/kg
5 days/week, 13 weeks
5 days/week, 13 weeks
5 days/week, 13 weeks
5 days/week, 13 weeks
rat
rat
rat
rat
conditioned reflexes; Increased
prothromb time and altered
enzyme activities
Increased liver weights; polyurla NTP, 1982
1n males; Increased urinary por-
phyrlns; hepatic necrosis and
degeneration; renal tubular
degeneration; thymlc lymphold
depletion; and hematologlc and
clinical changes
Increased liver weights; hema- NTP, 1982
tologlc and clinical changes;
hepatic necrosis
Increased liver weights; henna- NIP, 1982
tologlc and clinical changes;
some hepatic necrosis
Hematologlc and clinical changes NIP, 1982
Hematologlc and clinical changes NTP, 198?
-------
1ABLF 13-2 (cont.)
Route
Concentration
or Dose
Regimen
Subject
Effect
Reference
Oral {cont.) 500 rug/kg
CO
i
250 mg/kg
5 days/week, 13 weeks
5 days/week, 13 weeks
30, 60, 125 mg/kg 5 days/week, 13 weeks
Subcutaneous unspecified repeated
mouse
mouse
mouse
rabbit
Increased mortality; Increased
liver weights; Increased urinary
and liver porphyMns; hepatic
necrosis and degeneration; heart
and skeletal muscle lesions;
lymphold depletion of thymus and
spleen
Hepatic necrosis and degeneration
1n males; no effects In females
No effects
Blood dyscraslas, (agranulo-
cytosls)
NTP, 1982
NTP, 1982
NTP, 1982
Ware and West, 1977
•Source: Modlfed from U.S. EPA, 1980c
INJ
cr>
CO
-------
00
CO
cr
TABLE 13-3
Subchronlc Toxlclty of 1,4-D1chlorobenzene*
Route
Concentration
or Dose
Regimen
Subject
Effect
Reference
CO
i
Inhalation 105 mg/m3
4800 mg/m3
4600-4800 mg/m3
2050 mg/m'
1040 mg/m3
950 mg/m3
Oral
CO
\
rsj
\
CD
900 mg/m3
580 mg/m3
1000 mg/kg per
dose (tube)
7/0 mg/kg/day
600 mg/kg/day
(tube)
0.5 hours/day, 5-9 days
8 hours/day, 5 days/week,
up to 69 exposures
8 hours/day, 5 days/week,
7 hours/day, 5 days/week,
6 months
7 hours/day, 5 days/week.
16 days
7 hours/day, 5 days/week,
157-219 days
8 hours/day, 2 weeks
7 hours/day, 5 days/week,
6-7 months
92 doses In 219 days
up to 5 days
5 days/week, 20 doses
rabbit
rat, guinea pig,
rabbit
rabbit
rat, guinea pig
rat, guinea pig
rat, guinea pig,
rabbit, mouse,
monkey
mouse
rat, guinea pig,
mice, rabbit,
monkey
rabbit
rat
rat
Granulocytopenla; Irritation; CNS
and lung toxlclty; death (12/18)
Severe Irritation; CNS depression
and collapse; liver, kidney, lung
pathology; deaths
Tremors, weakness, nystagmus;
some deaths
Growth depression, Increased liver,
kidney weight; liver pathology
(necrosis, fatty degeneration,
swelling, flbrosls)
Increased liver, kidney weight
(rat); lung, liver pathology
Growth depression (guinea pig);
Increased liver, kidney weight;
hlstologlcal liver changes
(cloudy swelling, granular
degeneration) 1n rats, no adverse
effects reported 1n rabbit, mouse
or monkey
Respiratory excitation; liver
pathology, deaths; at serum
concentration of 39 mg/l
No adverse effects on several
parameters
CNS depression; weight loss;
liver degeneration and necrosis;
deaths
Hepatic porphyrla
Hepatic centrolobular necrosis;
cloudy swelling, renal tubular
epithelium, and casts
Zupko and Edwards,
1949
HolUngsworth et al.
1956
P1ke. 1944
HolUngsworth et al.
1956
HolUngsworth et al.,
1956
HolUngsworth et al.,
1956
Ir1e et al., 1973
Holllngsworth et al.,
1956
HolUngsworth et al.,
1956
Rlmlngton and Zlegler,
1963
HolUngsworth et al . ,
1956
-------
TABLE 13-3 (cont.)
CO
i
ro
Route Concentration
or Dose
Oral (cont.) 5000 mg/kg diet
500 mg/kg/day
(tube)
376 mg/kg/day
250 mg/kg/day
Regimen Subject
up to 35 days Peking duck
5 days/week. 263 doses In rabbit
367 days
5 days/week, 138 doses In rat
192 days
3 days rat
Effect
Death 1n 3/10.
CNS depression;
pathology
Increased liver
liver cirrhosis
Retarded growth
weight loss; liver
and kidney weight;
and focal necrosis
Induced liver metabolism enzyme
Reference
HolUngsworth et al . ,
1956
HolUngsworth et al . ,
1956
HolUngsworth et al. ,
1956
Arlyoshl et al. .
188 mg/kg/day
20-40 mg/kg/day 2 weeks
18.8 mg/kg/day
5 days/week, 138 doses 1n rat
192 days
5 days/week, 138 doses In
192 days
rat
rat
system
Increased liver and kidney weight
Induced liver metabolism enzyme
system
No adverse effects detected
1975a,b
HolUngsworth et al.,
1956
Carlson and Tardlff,
1976
HolUngsworth et al.,
1956
*Source: U.S. EPA, 1980c
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3/26/84
Summary of Subchronlc and Chronic Toxldty Studies on Trlchlorobenzenes
Species Route Dose
Rat Inhalation 74.2. 742 or
7423 mg/m'
of 1,3,5-TCB
Rats, rabbits. Inhalation 223 or 742 mg/m'
two dogs of 1.2,4-TCB
Rat Inhalation 22.3 or
74.2 mg/ms
of 1,2.4-TCB
Rat Inhalation • 186, 371 or
742 mg/m»
of 1,2.4-TCB
Rabbits, Inhalation 186, 371 or
monkeys 742 mg/ms
of 1.2,4-TCB
Monkey oral 1. 5. 25, 90,
125 or 173.6
mg/kg/day
of 1.2.4-TCB
Rat oral 50, 100 or
200 mg/kg/day
of 1,2,4-TCB
Rat oral 10, 20 or
40 mg/kg/day
of 1,2,4-TCB
Mouse oral 600 ppm diet
(0.078 mg/kg/
day) of
1,2,4-TCB
Duration
6 hr/day, 5 day/wk
for up to 13 wk
7 hr/day. 5 day/wk;
total of 30 expo-
sures In 44 days
6 hr/day, 5 day/wk,
3 mo
7 hr/day, 5 day/wk,
26 wk
7 hr/day, 5 day/wk,
26 wk
30 days
30. 60. 90 or
120 days
90 days
6 mo
Effects Reference
No hepatotoxlclty; three high-dose rats had Sasmora and Palmer,
squamous metaplasia and focal hyperplasla 1981
of respiratory epithelium, believed to be
reversible
Increase 1n urinary excretion of porphyrla Kodba et al., 1981
1n exposed rats; Increase In liver weights
In high-dose rats and dogs; Increased kid-
ney weights 1n high-dose rats
Increase In urinary porphyrln excretion 1n Watanabe et al., 1978
high-dose rats; no effects In 22.3 mg/ms
group
Enlarged hepatocytes and nondose-dependent Coate et al., 1977
hepatocytes vacuollzatlon, liver granulance,
biliary hyperplasla and kidney hyaline de-
generation at 4 and 13 wk; no hlstopathology
evident at 26 wk
No treatment related changes at 26 wk Coate et al., 1977
<25 mg/kg/day - no effects observed; Smith et al., 1978
>90 mg/kg/day - observed toxic Hy and death
Increases In liver weights, Hver porphyMns Carlson, 1977b
and urine porphyrlns, dose and time related
Increase 1n I1ver-to-body weight ratio In Carlson and Tardlff,
high-dose group; changes 1n enzyme actlva- 1976
tlon at all doses
No effects Goto et al., 1972
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TABLE 13-4 (cont.)
Species
Guinea pig
House
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** Rats
Rabbits
Route
dermal
dermal
oral
(drinking
water)
dermal
Dose
0.5 ml/day
of 1,2,4-TCB
0,003 mi/pa1nt-
Ing of 30 and
60X solution 1n
acetone of
1.2.4-TC8
25. 100 or
400 mg/i
of 1.2,4-TCB
30, 150 or
450 mg/kg/day
of 1,2.3-TCB
Duration
5 day/wk, 3 wk
2 t1raes/wk, 2 yr
FQ to F2
generations
5 day/wk, 4 wk
Effects
Death following extensor convulsion; livers
showed necrotlc fod
Painting Induced excitability, panting and
epidermal thickening. Inflammation and
keratlnlzatlon; Increased organ weights and
mortality
Enlarged adrenals 1n FQ and F-j generations
Dose-related skin Irritation; Increase 1n
urinary coproporphyMn 1n high-dose males
and slight pallor of liver In males and
females
Reference
Brown et al . , 1969
Yamamoto et al . , 1957
Robinson et al . , 1981
Rao et al., 19B2
1,2,3-TCB = 1,2,3-trlchlorobenzene; 1,2,4-TCB = 1,2,4-trlchlorobenzene; 1.3,5-TCB = 1,3,5-tr1chlorobenzene
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TABLF 13-S
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3/26/84
Summary of Toxlclty Studies on Tetrachlorobenzenes
Species Route Dose Duration
Rat oral 0.5-500 mg/kg 28 or 90 days
of diet
1,2,4.5-TeCB
Rat oral 0.001, 0.005. 8 mo
0.05 mg/kg/day
1.2.4,5-TeCB
RabbH oral 0.001, 0.005, 8 mo
0.05 mg/kg/day
, 1,2,4,5-TeCB
Rat oral 75 mg/kg/day 2 mo
1,2,4,5,-TeCB
Dog oral 5 mg/kg/day 2 yr exposure,
1,2,4,5-TeCB 22 mo recovery
Pregnant rats oral 50, 100, days 6-15 of
200 mg/kg/day gestation
1,2,4,5-TeCB
Pregnant rats oral 50, 100, days 6-15 of
200 mg/kg/day gestation
1,2,3,4-TeCB
Pregnant rats oral 50, 100, days 6-15 of
200 mg/kg/day gestation
1,2,3.5-TeCB
1.2,4.5-TeCB = 1 .2.4.5-tetrachlorobenzene
1.2,3,4-TeCB =- 1 ,2.3.4-tetrachlorobenzene
Effects
Increased liver and kidney weights and
hlstologlcal changes 1n liver and kidneys;
Increases 1n HFO activity, serum cholesterol
values
No effects observed 1n 0.001 mg/kg/day dose
group; 0.005 and 0.05 mg/kg/day doses caused
disruption 1n conditioned reflexes, Increases
1n liver weight coefficients and decrease 1n
serum SH groups
No effect observed In 0.001 mg/kg/day dose
group; 0.05 mg/kg dose caused disorder of
liver glycogen formation, altered serum SH
group levels, Increase 1n blood hemoglobin
and peripheral retlculocyte levels
Altered biochemical parameters Indicating
changes In hepatic and hematopoUlc horaeo-
stasls
No controls used; elevated SAP and total
b1!1rub1n, returned to normal range 3 mo
after exposures ended
High-dose lethal to 9/10 of treated dams;
organ weight changes, elevated serum
cholesterol and liver metabolism enzymes,
no Indication of those changes were dose-
related
Induced maternal toxldty and Increased
lethality of pups at 200 mg/kg/day
Increased lethality In 200 mg/kg/day group
pups; one pup malformed and minor chondro-
genlc delay In other pups
Reference
Vllleneuve et al. ,
1983
Fomenko, 1965
Fomenko, 1965
Fomenko, 1965
Braun et al., 1978
RuddUk et al.. 1981
RuddUk et al.. 1981
RuddUk et al., 1981
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TABLE 13-6
Summary of Subchronlc, Reproductive and Teratogenlc Toxldty Studies on Pentachlorobenzene
Species
Rat (female)
Route
oral
(diet)
Dose Duration
125, 250. 500 180 days
or 1000 mg/kg
1n diet
Effects
Changes In hematologlc parameters In high-
dose group; Increase 1n liver weights,
hepatic hypertrophy and vacuollzatlon 1n
500 and 1000 mg/kg groups; Increased kid-
ney weight 1n high-dose group
Reference
Under et al., 1980
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Rat (male) oral 125 or 1000
(diet) mg/kg 1n diet
Rat oral 125, 250, 500
(offspring) (diet) or 1000 mg/kg
1n mothers diet
Mice oral 50 or 100
mg/kg/gavage
Rat oral 50, 100 or 200
mg/kg/gavage
100 days
gestation and
during suckling
days 6-15 of
gestation
days 6-15 of
gestation
High-dose group Induced changes In hemato-
loglc parameters; hepatic and renal
histology and Increase 1n liver, kidney
and adrenal weights
Offspring treated with >250 mg/kg/d1et were
adversely affected (reduced survival, body
weights and Increased liver weights, hepato-
cellular enlargement)
Increase 1n liver weights of dams; no
adverse effects on total development or
survival
No observed toxldty In adult rats; In-
creased total deaths at all doses, but not
In dose-related manner; extra ribs 1n ex-
posed fetuses and sternal defects In 200
mg/kg group
Under et al., 1980
Under et al., 1980
Courtney et al., 1979
Khera and Vllleneuve,
1975
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TABLE 13-7
Summary of Toxldty Studies on Hexachlorobenzene
Species
Route
Dose
Duration
Effects
Reference
Rat
(females)
Rat
oral
oral
(diet)
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Rat
(females)
oral
(diet]
100 mo/kg every other
day
0.5 mg/kg/day
2.0 mg/kg/day
8.0 mg/kg/day
32.0 mg/kg/day
weekly
100 mg/kg diet
up to 43 days
15 weeks exposed and
held to 48 weeks
15 weeks exposed and
held to 48 weeks
15 weeks exposed and
held to 48 weeks
15 weeks exposed and
held to 48 weeks
Rat oral
(females) (gavage)
Rats oral
(females) (gavage)
50 mg/kg every other
day
0.5 mg/kg twice
weekly
2.0 mg/kg twice
weekly
8.0 mg/kg twice
weekly
32.0 mg/kg twice
15 weeks
29 weeks
29 weeks
29 weeks
29 weeks
98 days
Suggested covalent binding of hexachlorobenzene Koss et al.,
metabolites to cyto3o!1c proteins 1980a
Transient Increases 1n liver porphyrln levels Ku1per-Goodman
1n females after termination of exposure et al.. 1977
Increases 1n liver porphyrln levels 1n females
after termination of exposure, Increased size
of centrllobular hepatocytes
Increased liver weights, Increased liver,
kidney and spleen porphyrln levels In females
(porphyrla), centrllobular liver lesions espe-
cially 1n females at 48 weeks
Increased mortality 1n females. Intension
tremors 1n males and females and ataxla In a
few females. Increased liver, kidney and
spleen weights, Increased liver, kidney and
spleen porphyrln levels 1n females (porphyrla),
centrllobular liver lesions and splenomegaly
Increased liver, kidney, spleen and adrenal Koss et al.,
weights, porphyrla (Increased liver porphyrln 1978b
levels and Increased excretion of porphyrlns
and precursors), tremors, hair loss and skin
lesions
Increase 1n relative liver weight
Bdger et al.
1979
Increase 1n relative liver weight, moderately
enlarged hepatocytes
Porphyrla, markedly enlarged hepatocytes,
Increase 1n relative liver weight
Porphyrla, markedly enlarged hepatocytes,
Increase In liver weights
Porphyrla (Increased liver lobe porphyrlns). Smith et al.
decreased activity of uroporphyrlnogen 1980
decarboxylase
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TABLE 13-7 (cont.)
oo
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Species Route
Rat oral
(diet and
nursing!
Rat oral
(diet)
Dose
50 mg/kg diet
150 mg/kg diet
500, 1000 or 2000
mg/kg diet
Duration
gestation until
5 weeks of age
gestation until
5 weeks of age
3 weeks
Effects
Depressed resistance to L. monocytogenes and
T. splralls. enhanced thymus-dependent antibody
response
Increased serum IgM and IgG, depressed resis-
tance to L. monocytogenes and T. splralls.
enhanced thymus-dependent antibody response.
Increased liver and adrenal weights
Dose-related Increases In relative spleen,
lymph nodes, liver, adrenals, thyroid, testes
Reference
Vos et al
1979b
Vos et al.
1979a
< •
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Rat
Rat
(male)
Rat
( f ema 1 e )
Rat
(female)
Rat
Rat
(females)
oral
(diet)
oral
(diet)
oral
(diet)
oral
(gavage)
oral
(gavage)
oral
(gavage)
2000 mg/kg diet
2000 mg/kg diet
3000 mg/kg diet
50, 100 or 200 mg/kg
14 mg/kg every other
day
100 mg/kg every
other day
10 weeks
100 days
11 weeks
120 days
103 days
6 weeks
held for
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Rat
(females)
Rat
oral
(diet)
oral
(diet)
6-8 mg/kg/day
75 mg/kg diet
(4-5 mg/kg/day)
150 mg/kg diet
(8-9.5 mg/kg/day)
18 months
75-90 weeks
up to 2 years
and kidney weights, dose-related Increase In
serum IgM levels, no change In serum IgG
levels, dose-related pathological changes 1n
liver, lymph nodes and spleen
Porphyrla found microscopically at 5 weeks and
grossly at 10 weeks using fluorescence
Elevated hepatic enzymes by 1 week and Increased
urinary porphyrln and ALA levels (porphyrla) as
early as 40 days
Decreased uroporphyrlnogen decarboxylase
activity and porphyrla after 4 weeks
Dose- and time-dependent Increase In liver and
urine porphyrlns (porphyrla)
Porphyrla In treated females, susceptibility of
females to porphyrla may be related to estrogen
levels
Porphyrla (liver uroporphyrln levels peaked 7
months postexposure and levels had not returned
to normal by 18 months), decreased liver proto-
porphyrln and coproporphyrln levels. Inhibition
of uroporphyrlnogen decarboxylase activity
until 18 months postexposure
Decline 1n body weights, porphyrla, enlarged
livers and liver tumors
Porphyrla, time-related appearance of severe
hepatic and renal pathologies, after 1 year In-
creases In hepatomas, hepatocardnomas, bile duct
adenomas, renal adenomas and renal carcinomas
Gralla et al.,
1977
Llssner
et al., 1975
Elder et al.,
1976
Carlson, 1977b
R1zzard1n1 and
Smith. 1982
Koss et al.,
1983
Smith and
Cabral. 1980
Lambrecht et
al., 1983a,b
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TABLE 13-7 (cont.)
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Species Route
Rat oral
(diet)
oral
(diet and
nursing)
Rat oral
(diet)
Dose
0.32, 1.6, 8.0 or
40 mg/kg diet
0.32 or 1 .6 mg/kg
diet
8.0 rag/kg diet
40 mg/kg diet
10 or 20 mg/kg diet
40 mg/kg diet
80 mg/kg diet
Duration
-130 days
gestation through
lifetime (130 weeks)
gestation through
lifetime (130 weeks)
gestation through
lifetime (130 weeks)
Fg to F4 generations
FQ to F4 generations
FQ, to F4 generations
Effects Reference
Hematologlcal changes at all dose levels 1n Arnold et al.,
males, Increases In liver and heart weights 1n 1983
males at 8.0 and 40 ppm diets, no treatment-
related effects observed tn bred females
Glycogen depletion 1n 1.6 mg/kg males; no
effects reported at 0.32 mg/kg
Increase In liver pathologies
Increased mortality as pups. Increase In liver
and kidney pathologies, Increase In adrenal
pheochromocytomas In females and parathyroid
tumors In males
No effects reported Grant et al.,
1977
Increases 1n liver weights and aniline
hydroxylase activity
Decreased body weights, fj and F4 generations had
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Rat
Rat
Rat
oral
(diet)
oral
(diet)
oral
(diet)
160 mg/kg diet
320 and 640 mg/kg
diet
60, 80. 100, 120 or
140 mg/kg diet
0 or 80 mg/kg diet
80 mg/kg diet
FQ to F^ generations
FQ to F4 generations
F0 to F1a and Flb
generations
gestation and
nursing or cross
nursed with controls
? weeks pr lor to
mating to 35-36 days
after weaning
decreased lactation Index and postnatal viability
and Increased stillbirths
Increased mortality and decreased lactation
Index starting 1n F] generation
20 and 50% mortality In F0 320 and 640 mg/kg
groups, respectively, greatly reduced fertility
Index and Utter size and Increase 1n still-
births, viability Index zero 1n F]
Increased mortality 1n all groups at 21 days,
21-day 1059 values for pups were 100 and 140
mg/kg for F]a and FU, generations, respectively
Nursing exposure produced greater effects than
did gestatlonal exposure, effects noted were:
smaller brains, hearts, kidneys and spleens,
Increased liver weights
Increased porphyrln levels and decreased liver
esterase activity 1n dams, no changes 1n
gestation Indices or neonatal survival
Kltchln
et al., 1982
Mendoza
et al., 1978
Mendoza
et al. , 1979
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TABLE 13-7 (cont.
OS
Species
Rat
Route
oral
(gavage)
Dose
10. 20, 40, 60, 80
or 120 mg/kg
Duration
days 6-21 of gesta-
tion
Effects
Maternal toxldty (weight loss, tremors and
convulsions) and reduced fetal weights at 120
Reference
Khera. 1974
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Mouse
House
(male)
Mouse
(male)
Mouse
Mouse
Hamster
Hamster
Cats
(breeding
females)
oral
(diet)
oral
(diet)
oral
(diet)
oral
(diet)
oral
(gavage)
oral
(diet]
•
oral
(diet]
oral
(diet]
2.5. 25 or 250
mg/kg diet
10 mg/kg diet (8.4
(mg/mouse/24 weeks)
or 50 mg/kg diet
(35.3 mg/mouse/
24 weeks)
167 mg/kg diet
6. 12, 24 and 36*
mg/kg/day
100 mg/kg/day to
pregnant mice
200 or 400 mg/kg
diet
4, 6 or 16 mg/kg/day
3 or 8.7 mg/day/cat
21 days
24 weeks
3-6 weeks
101-120 weeks
*{15 weeks exposed
held until 120
weeks)
days 7-16 of
gestation
90 days
Hfespan
14? days
and 80 mg/kg maternal doses, dose-related In-
crease In Incidence of unilateral and bilateral
14th rib, sternal defects were also noted In
one experiment
Dose-related Increase In liver and decrease In EUssalde and
prostate and seminal vesicle weights, dose- Clark, 1979
related alterations In testosterone metabolism,
altered hepatic enzyme levels
Dose-related reduction In weight gain, no tumor Shlral et al.,
pathology observed 1978
Impairment 1n host resistance as measured by Loose et al.,
Increased sensitivity to S. typhosa and P. 1978a,b
bergherl. and decrease In IgA levels
Reduced growth rate at all dose levels, short- Cabral et al.,
ened Hfespan associated with tremors and con- 1979
vulslons 1n 24 and 36 mg/kg/day groups, dose-
dependent Increase 1n liver-cell tumors In the
12, 24 and 36 mg/kg/day dose groups
Increased maternal livers and decreased fetal Courtney
body weights, Increased Incidence of abnormal et al., 1976
fetuses per litter observed
Preclrrhotlc and clrrhotlc hepatic lesions, Lambrecht
bile-duct hyperplaslas and hepatomas et al., 1982
Shortened Hfespan In 16 mg/kg/day group, In- Cabral et al.,
crease In hepatomas at all dose levels, Increase 1977
1n liver haemang1oendothel1oma In males and
females and an Increase 1n thyroid alveolar
adenomas 1n males 1n 16 mg/kg/day group
Weight loss and Increased disease susceptibility Hansen et al.,
In bred females, dose-related decrease In litter 1979
size and survival of offspring, hepatomegaly In
offspring
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1ABLF 13-7 (cont.)
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Species
Minks
Dog
(female)
Dog
Monkey
(female)
Monkey
Route
oral
(diet)
oral
(capsule)
oral
(capsule)
oral
(gavage)
oral
(nursing)
Dose
1 or 5 mg/kg diet
50 or 150 mg/kg/day
1, 10, 100 or 1000
mg/day/dog
8, 32, 64 or 128
mg/kg/day
7.51-186 ppro milk
Duration
during gestation
until 17 weeks of
age
21 days
1 year
60 days
60 days
Effects
Dose-related Increase In offspring mortality,
Induction of hepatic MFO enzymes In exposed
offspring
Liver and hepatocyte enlargement, dose-Induced
electroencephalogram dysrhythmlas
Increase In mortality, neutrophllla, and
anorexia 1n the 100 and 1000 mg dose groups,
dose-related nodular hyperplasla of gastric
lymphold tissue 1n all treated animals
Dose-related pathology In liver, kidney, ovaries
and thymus
2 of 3 Infants died as a result of exposures
Reference
Rush et al . ,
1983
Sundlof
et al., 1981
Gralla et al . ,
1977
latropoulus
et al., 1976
Bailey et al. ,
1980
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TABLE 13-8
Comparison313 of Toxic Effects of Chlorinated Benzene Isomers 1n Rats
Organ/Body Altered Porphyrlnogenlc Neurologic Hematopo1et1c Renal Hepatic Adrenal Reproductive Carcinogenic
Chemical Weight Changes Enzyme Effects Effects Effects Effects Effects Effects and Teratogenlc Effects
Levels Effects
CO
ro
CO
ro
Nono-CB ( I )
(0)
1.2-OCB (I)
(0)
1.3-DCB (I)
(0)
1,4-DCB (I)
(0)
1.2.3-TCB (I)
(0)
1,2,4-TCB (I)
(0)
1,3,5-TCB (I)
(0)
1.2,3.4-TeCB (I)
(0)
2000 mg/m3
(90)d
100 mg/kg/day
(99)
125 mg/kg (90)6
950 mg/m3
(219)c
188 mg/kg
(192)e
186 mg/m3 (90)c
40 mg/kg/day
(90)
1 .0 mg/m3 1 .0 mg/m3
(60) (60)
500 500 mg/kg/day 500 mg/kg/day
mg/kg/day (90) (90)
(90)
455 mg/m3 (15)
0.1 500 mg/kg (90)e 0.01 0.1 mg/kg/day
mg/kg/day mg/kg/day (150)
(150) (150)
4800 mg/m3
(97)f
20 770 mg/kg/day
mg/kg/day (5)
(14)
74.2 mg/m3
(90)d
10 100 mg/kg/day
mg/kg/day (30)
(90)
200 mg/kg/day
0.1 mg/m3
(80)
500
mg/kg/day
(90)
500 mg/kg
(90)e
4800
mg/m3
(97)f
500 mg/kg
(28)6
186 rag/m3
(90)c
0.1 mg/m3 345 mg/maC
(80) (168)
250
mg/kg/day
(90)
125 mg/kg
(90)e
950 mg/m3
376 mg/kg
(192)6
186 mg/m3
(90)c
33-56
mg/kg/day
(95)9
200 mg/kg/day
CD
(10)
(10)
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TABLE 13-8 (cont.)
Organ/Body Altered Porphyrlnogenlc Neurologic Hematopoletlc Renal Hepatic Adrenal Reproductive Carcinogenic
Chemical Weight Changes Enzyme Effects Effects Effects Effects Effects Effects and Teratogenlc Effects
Levels Effects
1,2,3,5-TeCB (I)
(0)
200 mg/kg/day
(10)
1,2,4,5-TeCB (I)
PCB
HCB
(0)
(I)
(0)
(I)
(0)
0.005 mg/kg/day
(240)
46 mg/kg/day
(180)
0.3 mg/kg/day
(130)
75
mg/kg/day
(60)
25
mg/kg/day
(10)
5 mg/kg/ 0.05 mg/kg/day
day (60) (105)
0.005
mg/kg/day
(240)
50 mg/kg
(105)n
75 mg/kg/day
(60)
97 mg/kg/day
(100)
0.01 mg/kg/day
(130)
97
mg/kg/day
(100)
2 mg/kg/
day (910)
46
mg/kg/day
(180)
2 mg/kg/
day (105)
75
mg/kg/day
(60)
2 mg/kg/
day (910)
200 mg/kg/day
(10)
16-31 mg/kg/day
(100)
10 mg/kg/day
(10)
4-5 mg/kg/day
(730)
CO
I
aAll values are the lowest dose level reported for each listed effect category, from the mammalian toxldty sections of Chapters 7-12, with dosing duration
listed 1n (days). A blank Indicates that the effect has not been reported In this species for this Isomer.
''From subchronlc, chronic, reproductive and teratogenlclty studies
cmg/m», 7 hours/day, 5 days/week
dmg/m8, 6 hours/day, 5 days/week
emg/kg, 5 days/week
fmg/m3, 8 hours/day, 5 days/week
9ln FQ and f-\ generations: enlarged adrenals
nmg/kg every other day
CO
ro I = Inhalation exposure; 0 = oral exposure
oo Hono-CB = monochlorobenzene; DCB = dlchlorobenzene; TCB = trlchlorobenzene; TeCB = tetrachlorobenzene; PCB = pentachlorobenzene; HCB = hexachlorobenzene
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to
TABLE 13-9
Comparison3-1* of Toxic Effects of Chlorinated Benzenes 1n Mice
Chemical
Organ/Body
Weight Changes
Altered
Enzyme
Levels
PorphyMnogenlc Neurologic Hematopo1et1c Renal Hepatic
Effects Effects Effects Effects Effects
Adrenal Reproductive Carcinogenic
Effects and Teratogenlc Effects
Effects
o
.£»
Hono-CB (I)
(0) 125 mg/kg/day
(90)
1.2-OCB (I)
(0) 500 mg/kg
(90)c
1,3-DCB (I)
(0)
1,4-DCB (I)
(0)
1,2,3-TCB (I)
(0)
1,2,4-TCB (I)
(0)
1,3,5-TCB (I)
(0)
1,2,3,4-TeCB (I)
(0)
1,2.3,5-TeCB (I)
(0)
1,2,4,5-TeCB (I)
(0)
250 mg/kg/day
(90)
500 mg/kg (90C
500 mg/kg/day 250 mg/kg/
(90) day (90)
500 rag/kg
900 mg/m3
60 mg/kg/
day (90)
250 mg/kg
(90)c
900 mg/m3
-------
03
CO
CO
I
en
TABLE 13-9 (cont.)
Chemical
PCB
HCB
(I)
(0)
(I)
(0)
Organ/Body
Weight Changes
50 mg/kg/day
(10)
0.01 mg/kg/day
(21)
Altered PorphyMnogenlc
Enzyme Effects
Levels
0.01 mg/kg/
day (21)
Neurologic Hematopoletlc
Effects Effects
24 mg/kg/
day (840)
Renal Hepatic Adrenal
Effects Effects Effects
12 mg/kg/
day (840)
Reproductive
and Teratogenlc
Effects
100 mg/kg/day
(10)
Carcinogenic
Effects
12 rog/kg/day
(840)
aAll values are the lowest dose level reported for each listed effect category, from the mammalian toxldty sections of Chapters 7-12, with dosing duration
listed In days. A blank Indicates that the effect has not been reported 1n this species for this Isomer.
bFrom subchronlc, chronic, reproductive and teratogenldty studies
cmg/kg, 5 days/week
d8 hours/day
I = Inhalation exposure; 0 = oral exposure
Mono-CB = monochlorobenzene; DCB = dlchlorobenzene; TCB = tMchlorobenzene; TeCB = tetrachlorobenzene; PCB = pentachlorobenzene; HCB = hexachlorobenzene
rvj
-------
oo
CO
01
3»
TABLE 13-10
Comparison3-1* of Toxic Effects of Chlorinated Benzenes 1n Rabbits
CO
1
Chemical
Hono-CB (I)
(0)
1,2-DCB (I)
(0)
1.3-DCB (I)
(0)
Organ/Body Altered PorphyMnogenlc Neurologic Hematopo1et1c Renal
Weight Changes Enzyme Effects Effects Effects Effects
Levels
345 mg/m3
(168)c
Hepatic Adrenal Reproductive Carcinogenic
Effects Effects and Teratogenlc Effects
Effects
1,4-DCB
(I)
(0) 500 mg/kg
(367)6
1,2,3-TCB (I)
(0)
1,2,4-TCB (I)
(0)
1,3,5-TCB (I)
(0)
1,2,3.4-TeCB (I)
(0)
1,2.3,5-TeCB (I)
(0)
4800 mg/m3
(97}d
500 mg/kg
s
4800 mg/m3 4800 mg/m3
(97)d
mg/kg
e
500
oo
-------
CD
TABLE 13-10 (cont.;
Chemical
Organ/Body
Weight Changes
Altered
Enzyme
Levels
PorphyMnogenlc Neurologic Hematopo1et1c Renal
Effects Effects Effects Effects
Hepatic Adrenal Reproductive Carcinogenic
Effects Effects and Teratogenlc Effects
Effects
1,2.4,5-TeCB (I)
(0)
0.05 mg/kg/day
(2*0)
CO
1
ro
_^ i
PCB
HCB
(I)
(0)
(I)
(0)
aAll values are the lowest dose level reported for each listed effect category, from the mammalian toxldty sections of Chapters 7-12, with dosing duration
listed 1n days. A blank Indicates that the effect has not been reported 1n this species for this Isomer.
bFrom subchronlc, chronic, reproductive and teratogenldty studies
cmg/m*, 7 hours/day, 5 days/week
dmg/m3, 8 hours/day, 5 days/week
emg/kg, 5 days/week
I = Inhalation exposure; 0 = oral exposure
Hono-CB = monochlorobenzene; DCB = dlchlorobenzene; TCB = tMchlorobenzene; TeCB = tetrachlorobenzene; PCB = pentachlorobenzene; HCB = hexachlorobenzene
tvj
-------
CXI
CO
cri
TABLE 13-11
Comparison3-11 of Toxic Effects of Chlorinated Benzenes 1n Dogs
CO
rv?
CD
Organ/Body
Chemical Weight Changes
Hono-CB (I) 1500 mg/m3
(90)«
(0)
1,2-DCB (I)
(0)
1.3-DCB (I)
(0)
1,4-OCB (I)
(0)
1.2,3-TCB (I)
(0)
Altered Porphyr1nogen1c Neurologic Hematopoletlc
Enzyme Effects Effects Effects
Levels
2000 mg/m3 2000 mg/m3
(90)c (90)c
272.5 mg/ 272.5 mg/kg/
kg/day (90) day (90)
Renal Hepatic Adrenal Reproductive
Effects Effects Effects and Teratogenlc
Effects
2000 mg/m3 2000 mg/m3 2000 mg/m3
(90)c (90)c (90)c
272.5 mg/ 272.5 mg/
kg/day (90) kg/day (90)
Carcinogenic
Effects
1,2,4-TCB (I) 742 mg/m3 (44)d
(0)
1,3,5-TCB (I)
(0)
1.2.3.4-TeCB (I)
(0)
1,2,3,5-TeCB (I)
(0)
CO
-------
CD
CO
TABLE 13-11 (cont.)
Chemical
Organ/Body
Weight Changes
Altered
Enzyme
Levels
PorphyMnogenlc Neurologic Hematopo1et1c Renal
Effects Effects Effects Effects
Hepatic Adrenal Reproductive Carcinogenic
Effects Effects and Teratogenlc Effects
Effects
CO
1,2,4,5-TeCB (I)
(0)
5 mg/kg/day
(730)
PCB
HCB
(I)
(0)
(I)
(0)
50 mg/dog/ 100 ing/dog/day
day (21) (365)
50 mg/dog/
day (21)
aAll values are the lowest dose level reported for each listed effect category, from the mammalian toxldty sections of Chapters 7-12, with dosing duration
listed 1n (days). A blank Indicates that the effect has not been reported 1n this species for this Isomer.
bFrom subchronlc, chronic, reproductive and teratogenlclty studies
cmg/m3, 6 hours/day, 5 days/week
drag/m3, 7 hours/day, 5 days/week
I = Inhalation exposure; 0 = oral exposure
Mono-CB = monochlorobenzene; DCB = dlchlorobenzene; TCB = tMchlorobenzene; TeCB = tetrachlorobenzene; PCB = pentachlorobenzene; HCB = hexachlorobenzene
co
oo
-------
CO
CO
TABLE 13-12
Comparison3-15 of Toxic Effects of Chlorinated Benzenes 1n Monkeys
Organ/Body Altered Porphyr1nogen1c Neurologic Hematopo1et1c Renal Hepatic Adrenal Reproductive Carcinogenic
Chemical Height Changes Enzyme Effects Effects Effects Effects Effects Effects and Teratogenlc Effects
Levels Effects
co
i
CO
o
Mono-CB
1,2-DCB
1,3-DCB
1,4-DCB
1,2,3-TCB
1.2,4-TCB
(I)
(0)
(I)
(0)
(I)
(0)
(I)
(0)
(I)
(0)
(I)
(0)
1,3,5-TCB (I)
(0)
1,2,3.4-TeCB (I)
(0)
1.2,3,5-TeCB (I)
(0)
1,2.4.5-TeCB (I)
(0)
PCB
HCB
(I)
(0)
(I)
(0)
90 mg/kg/
day (30)
174 mg/kg/
day (30)
174 mg/kg/
day (30)
8 mg/kg/ 8 mg/kg/day
day (60) (60)
co
-P*
aAll values are the lowest dose level reported for each listed effect category, from the mammalian toxldty sections of Chapters 7-12, with dosing duration
listed 1n (days). A blank Indicates that the effect has not been reported 1n this species for this Isomer.
From subchronlc, chronic, reproductive and teratogenlclty studies
I = Inhalation exposure; 0 = oral exposure
Hono-CB = monochlorobenzene; DCB = dichlorobenzene; TCB = trlchlorobenzene; TeCB = tetrachlorobenzene; PCB = pentachlorobenzene; HCB = hexachlorobenzene
-------
because the variety of studies used to glean the effects Information were as
follows: the studies were conducted under a wide range of experimental
conditions; employed different study durations; used a variety of animal
strains and different group sizes; and designed to assess different end-
points. Nevertheless, these tables do allow for a broad comparison of the
toxic effects Induced by the 12 different chlorinated benzenes 1n a variety
of species.
After reviewing Tables 3-8 through 13-12, H can be seen that large data
gaps exist for many of the chlorinated benzenes, especially for 1,3-
dlchlorobenzene, the trlchlorobenzenes and the tetrachlorobenzenes. Also,
except for the rat and possibly the mouse, the effects from subchronlc and
chronic exposure to the different chlorinated benzenes 1n a variety of
animal species have not been studied. The Interpretation of possible
chlorinated benzenes structure activity relationships will, for the most
part, be left to the document reader. The only Interpretation that will be
proposed from these comparison tables Is an apparent trend, for many of the
toxic effect categories, of Increased toxlclty with Increased chlorlnatlon
of the benzene ring.
13.2.2. Estimated Toxlclty Thresholds. Estimated toxldty threshold
levels as determined from the studies discussed 1n the respective mammalian
toxlclty sections of Chapters 7-12 of this document are presented 1n Table
13-13.
13.3. CARCINOGENICITY STUDIES
Adequate evidence of the carc1nogen1c1ty of the different chlorinated
benzenes has only been found for hexachlorobenzene. The other chlorinated
benzenes either have not been studied for their carc1nogen1c1ty or the
studies that have been conducted are Inadequate.
1836A 13-31 04/16/84
-------
TABLE 13-13
CD
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CO
CO
CO
en
CD
"**
Compound
Honochlorobenzene
Moporhlorobenzene
Honochlorobenzene
Honochlorobenzene
Monochlorobenzene
Nonochlorobenzene
Honochlorobenzene
Honochlorobenzene
1 ,2-D1chlorobenzne
1 ,2-D1chlorobenzene
1 ,2-D1chlorobenzene
1 ,2-D1chlorobenzene
1 ,2-D1chlorobenzene
1 ,2-D1chlorobenzene
1 ,2-D1chlorobenzene
1 ,4-D1chlorobenzene
1 ,4-D1chlorobenzene
Species
dog
rat
dog
rat
rat
rat
rat
mouse
rat, rabbit,
monkey
guinea pig
rat
rat
rat
mouse (female)
mouse (male)
rat, guinea pig,
mouse, rabbit,
monkey
rat
iuxic i ty uai
Route
Inhalation
Inhalation
oral
oral
oral
oral
oral
oral
Inhalation
Inhalation
oral
oral
oral
oral
oral
Inhalation
oral
:a ror inreshold tstlnwtes
Dose
Concentration
0.75 mg/i (162 ppm),
6 hour/day, 5 day/week
2.0 mg/i, 6 hour/day.
5 day/week
27.3 mg/kg/day
50 mg/kg/day
14.4 mg/kg/day
125 mg/kg/day,
5 day/week
250 mg/kg/day.
5 day/week
60 mg/kg/day,
5 day/week
560 mg/m3.
7 hour/day, 5 day/week
290 mg/m3.
7 hour/day, 5 day/week
18.8 mg/kg, 5 day/week
0.001 mg/kg/day
30 mg/kg, 5 day/week
250 mg/kg, 5 day/week
125 mg/kg, 5 day/week
580 mg/m3,
7 hour/day, 5 day/week
18.8 mg/kg, 5 day/week
Dose
Duration
62 exposures
over 90 days
62 exposures
over 90 days
90 days
93-99 days
192 days
13 weeks
13 weeks
13 weeks
6-7 months
6.5 months
138 doses
5 months
13 weeks
13 weeks
13 weeks
6-7 months
138 doses
Effect
Level
NOEL3
NOEL3
NOEL3
NOELa
NOAELb
NOEL3
LOAEL3
LOAEL3
NOEL3
NOEL3
NOEL3
NOEL3
LOAEL3
NOEL3
NOEL3
NOEL3
NOELa
Reference
Monsanto. 1978
Monsanto, 1978
Monsanto, 1967a
Monsanto, 1967b
Irish, 1963
NTP, 1983
NTP, 1983
NTP, 1983
Holllngsworth
et al., 1958
Holllngsworth
et al.. 1958
Holllngsworth
et al.. 1958
Varshavskaya,
1967a
NTP. 1982
NTP, 1982
NTP, 1982
Hoi 1 Ingsworth
et al.. 1956
Hoi 1 Ingsworth
et al., 1956
-------
TABLE 13-13 (cont.)
00
co-~
ty>
3>
CO
CO
CO
Compound
1 , ?.4-Tr1chlorobenzene
1 ,2,4-Tdchlorobenzene
1 ,2,4-Trlchlorobenzene
1,3,5-TMchlorobenzene
1 ,2,4,5-Tetrachlorobenzene
Pentachlorobenzene
Pentachlorobenzene
Pentachlorobenzene
Pentachlorobenzene
Hexachlorobenzene
Hexachlorobenzene
Hexachlorobenzene
Hexachlorobenzene
Species
rat
rabbit, monkey
monkey
rat
rat, rabbit
rat
rat
rat (offspring)
rat (offspring)
rat
rat
rat
rat
Route
Inhalation
Inhalation
oral
Inhalation
oral
oral
oral
oral
oral
oral
oral
oral
oral
Dose
Concentration
22.3 mg/m'.
6 hour/day, 5 day/week
742 mg/m',
7 hour/day, 5 day/week
25 mg/kg/day
74.2 mg/m3,
6 hour /day, 5 day/week
0.001 mg/kg/day
250 mg/kg diet
(-16-31 mg/kg/day)
500 mg/kg diet
(-27-63 mg/kg/day)
125 mg/kg diet
(-14-16 mg/kg/day)
50 mg/kg/day
0.5 mg/kg/day
2.0 mg/kg/day
0.32 mg/kg diet
(0.01-0.04 mg/kg/day)
20 mg/kg diet
Dose
Duration
3 months
26 weeks
30 days
13 weeks
8 months
180 days
180 days
gestation and
suckling
days 6-15 of
gestation
15 weeks
15 weeks
gestation-
lifetime
F0 to F4
generations
Effect
Level
NOAELa
NOEL3
NOEL3
NOAEL3
NOEL3
NOEL3
LOAEL3
NOEL3
LOAEL3
NOAEL3
LOAEL3
NOEL3
NOEL3
Reference
Uatanabe et al. ,
1978
Coate et al . ,
1977
Smith et al.,
1978
Sasmore and
Palmer, 1981
Fomenko, 1965
Llnder et al. ,
1980
Llnder et al . ,
1980
Llnder et al. ,
1980
Khera and
Vllleneuve, 1975
Ku1 per -Goodman
et al.. 1977
Ku1 per -Goodman
et al.. 1977
Arnold et al . ,
1983
Grant et al . ,
1977
INJ
CT>
CO
Estimated toxldty thresholds as determined 1n the respective Mammalian "loxldty Sections of this document.
bEst1mated toxldty thresholds as found 1n U.S. EPA, 1980b.
NOEL - No-observed-effect level: That exposure level at which there are no statistically significant Increases In frequency or severity of
effects between the exposed population and Us appropriate control.
NOAEL -- No-observed-adverse-effect level: That exposure level at which there are no statistically significant Increases In frequency or
severity of adverse effects between the exposed population and Us appropriate control. Effects are produced at this dose, but they are not
considered to be adverse.
LOAtl - Lowest -observed-adverse-effeet level: The lowest exposure level In a study or group of studies which produces statistically signifi-
cant Increases In frequency or severity of effects between the exposed population and Its appropriate control
-------
The chlorinated benzenes for which animal carclnogenldty studies were
available for review were hexachlorobenzene, 1,2,4-tMchlorobenzene,
1,2-d1chlorobenzene and rnonochlorobenzene. One study which Included both
rats and mice, was available for rnonochlorobenzene and for 1,2-d1chloro-
benzene. The chronic studies which were available for hexachlorobenzene
Included two on hamsters, one on mice and four on rats as well as a few
studies which failed to qualify as cardnogenlclty tests.
All of the hexachlorobenzene cardnogenlcHy studies, with the exception
of one, conducted at low doses, yielded one or more sites of significantly
Increased tumor Incidence. The primary target organ appears to be the
liver, but thyroid, parathyroid and adrenal glands also showed Increases and
1n one Instance kidney tumors were Increased.
Malignant liver tumors occurred 1n one experiment on hamsters (Cabral et
al., 1977) where the Incidence of haemangloendothelloma was 6/30 (20%) 1n
treated males at 8 mg/kg bw/day compared with 0/40 (0%) 1n controls and an
Incidence of 7/60 (12%) 1n treated females at 16 mg/kg bw/day compared with
0/39 (0%) 1n controls. In an experiment 1n rats Lambrecht (1983) obtained
hepatocellular carcinoma 1n hexachlorobenzene-treated males with a frequency
of 3/52 (6%) compared to 0/54 (0%) 1n controls and of 36/56 (64%) 1n treated
females compared to 0/52 (0%) 1n controls. These effects were produced at
4-5 mg/kg bw/day.
Hepatoma was Increased as a result of hexachlorobenzene 1n two hamster
studies (Cabral et al., 1977; Lambrecht et al., 1982). In the latter report
the number of animals at risk was small and the Increase just detectable.
In the Cabral study at a dose of 4 mg/kg bw/day both males and females had a
14/30 (47%) Incidence of hepatoma while controls for each sex had 0/40
(0%). The Incidence went as high as 51/60 (85%) at the largest dose used.
1836A 13-34 03/30/84
-------
Cabral (1979) also found an Incidence of 3/12 (25%) 1n both male and female
mice administered 6 mg/kg bw/day hexachlorobenzene compared with 0/50 (0%)
1n controls. The rat studies 1n which hepatomas were reported are those of
Smith and Cabral (1980) and Lambrecht et al. (1983). In the study of Smith
and Cabral (1980) an Agus rat strain was used that 1s particularly suscepti-
ble to porphyrla and liver tumors. These animals, all female, gave 100%
yield of hepatoma 1n 14 animals compared to 0/12 (0%) 1n controls. Part of
that same study employed six female Wlstar rats 1n a treated group and 4 of
6 cases of hepatoma (67%) were reported compared with 0/4 (0%) 1n controls.
In Lambrecht's study at 4-5 mg/kg bw/day Sprague-Dawley rats developed
hepatoma 1n 19% of treated males and 46% of treated females while controls
for both sexes were 0/52 (0%). They also found hepatocellular carcinoma 1n
females with an Incidence of 36/56 (64%) at 4-5 mg/kg/day and 48/55 (87%) at
8-10 mg/kg/day.
The liver cardnogenldty and tumor1gen1c1ty of hexachlorobenzene,
therefore, seems established by repeated experiments 1n rats and hamsters
and by a single study 1n mice. A high Incidence 1s Induced with doses as
low as 4-5 mg/kg bw/day. This dosage appears to be effective In three
rodent species 1n Inducing hepatoma. In the Lambrecht (1983) study the oral
dose was nominally 4-5 mg/kg bw/day 1n the diet, but may have been higher
because of Inhalation exposure from hexachlorobenzene In the feed, since the
compound was not solublUzed 1n any liquid vehicle.
Other tumors were reported as well as those which occurred 1n the liver.
In male hamsters, thyroid tumors were significantly elevated at 16 mg/kg
bw/day In males and 1n a 2-generat1on study, rats of the F generation had
significant Increase In adrenal pheochromocytoma 1n females and parathyroid
1836A 13-35 03/30/84
-------
tumors 1n males. These tumors may not be spurious for the following
reasons. The doses Involved did not produce significant toxldty and H 1s
unlikely that nonspecific stress or systemic toxldty evoked these re-
sponses. Also, one of the observations made on humans accidentally exposed
to hexachlorobenzene, Initially and 1n a 25-year follow-up, 1s thyroid
enlargement well above expected levels for that area (Peters et al., 1982).
In addition, rats exposed to monochlorobenzene had a significant decrease 1n
pituitary adenoma Incidence suggesting that the endocrine balance may be
affected by chlorinated benzenes.
There was one report of a significant Increase 1n renal cell adenoma In
rats of both sexes at 4-5 mg/kg bw/day.
The studies on 1,2-d1chlorobenzene and monochlorobenzene were conducted
at doses which were well below the MTD as estimated by subchronlc range
finding studies. In the case of 1,2-d1chlorobenzene In rats no Increase 1n
tumors or other pathology was found. In mice no tumor type was signifi-
cantly Increased compared with controls.
In the case of the monochlorobenzene a significantly Increased Incidence
of neoplastlc nodules 1n male rats was Induced at a gavage dose of 120 mg/kg
bw/day. The data on the 1,2-d1chlorobenzene and monochlorobenzene are In-
adequate to draw conclusions concerning the human carclnogenlclty of these
compounds.
For hexachlorobenzene the studies showing positive tumor responses are
summarized 1n Table 13-14. It has Induced liver tumors 1n hamsters, mice
and rats, thyroid tumors 1n hamsters, and kidney and adrenal tumors 1n
rats. Using the IARC ranking system for classifying the evidence of car-
dnogenldty, hexachlorobenzene would be a Group 2 chemical which IARC
describes as a probable carcinogen 1n humans.
1836A 13-36 04/17/84
-------
XB
TABLE 13-14
Summary of Tumors Induced 1n Rodents by HCB
CO
1
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— J
o
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Species
Hamsters
Hamsters
Hamsters
Hamsters
Mice
Rats
Rats
Rats
Rats
Rats
Lowest
to Produce Tumor
mg/kg bw/day
4
8 maTe; T6 female
T6
200 ppm
6
6-8
6-8
F] dose unknown
In utero, adult =
0.4
FI dose unknown
1n utero, adult =
0.4
V1t. A content
varied, HCB = 0.4
Males
Tumor X
Type Treated/Control
hepatoma 47/0
haemangloendo- 20/0
theTloma of
Tlver
thyroid adenoma 14/0
hepatoma 8/0
hepatoma 25/0
parathyroid 25/4
adrenal pheo- 35/23
chromocytoma
none
Females
Tumor X
Type Treated/ControT
hepatoma 47/0
haemangloendo- T2/0
theUoma of
Tlver
thyroid adenoma 6/0
hepatoma 8/0
hepatoma 25/0
hepatoma TOO/0
(Agus)
hepatoma 67/0
(Wlstar)
adrenaT pheo- 35/4
chromocytoma
none
Reference
CabraT, 1977
Cabral, 1977
Cabral, T977
Lambrecht et al.. 1982a
CabraT, 1979
Smith and
CabraT, 1980
Smith and
CabraT, T980
Arnold. T983
ArnoTd, T983
ArnoTd, 1983
CO
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TABLE 13-14 (cont.)
03
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CD
Species
Rats
Rats
Rats
Males
Lowest
to Produce Tumor Tumor
mg/kg bw/day Type
4-5 hepatoma
4-5 hepatocellular
carcinoma
4-5 renal cell
adenoma
Females
X Tumor
Treated/Control Type
19/0 hepatoma
6/0 hepatocellular
carcinoma
79/13 renal cell
adenoma
Reference
X
Treated/Control
46/0 Lambrecht. 1983
64/0 Lambrecht. 1983
13/2 Lambrecht. 1983
o
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A quantitative estimate of the carcinogenic potency of hexachlorobenzene
and an upper-bound estimate of the risks from continuous human exposure to 1
vig/m3 1n air and 1 yg/8. 1n drinking water were made from data on the
hepatocellular carcinoma response 1n female rats. The upper-bound slope of
the dose-response curve, q * 1s 1.7/(mg/kg/day), giving a potency Index
which is 1n the second quartlle of 54 suspect carcinogens evaluated by the
Carcinogen Assessment Group. The unit risks for air and water exposures are
4.9x10"" for 1 yg/m3 1n ambient air and 4.9xl(T5 for 1 pg/S. In
drinking water. Corresponding estimates from 13 other data sets, encompass-
ing different tumor sites and animal species, fall within a factor of 10 of
these estimates except for thyroid tumors 1n hamsters, which give estimates
of about 1/20 of the potency based on the rat hepatocellular carcinoma
response.
13.4. HUMAN STUDIES
Although animal studies Indicate that hexachlorobenzcne is carcinogenic
1n hamsters, rats and mice, there were no adequate ep1dem1ologic studies
available to corroborate these findings 1n humans. However, the human data
which has been collected were not designed to detect human carclnogenidty,
but rather provide a better understanding of hexachlorobenzene toxldty 1n
Infants (pink sore) and adults (porphyMa cutanea tarda) (Cam, 1963; CMpps
et al., 1981; Peters et al., 1966; Peters et al., 1982). In the studies of
hexachlorobenzene-lnduced toxldty, human consumption of hexachlorobenzene
through contaminated wheat was estimated at 50-200 mg hexachlorobenzene/
person/day (0.71-2.86 mg/kg bw/day for a 70 kg male); these doses were
sufficient to cause porphyrla cutanea tarda and other effects in 3000-5000
people (Courtney, 1979). Ep1dem1olog1c studies with occupationally-exposed
workers or people living In the vicinity of a chlorinated solvents plant
1836A 13-39 03/30/84
-------
were not designed to detect carcinogenic!ty. The exposure Information
provided by those studies Is not sufficient to relate dose level to effect
(Currier et al., 1980).
Two other chlorinated benzenes were reported to have effects 1n humans.
l,2-D1chlorobenzene (Zapata-Gayon et al., 1982) and 1,2,4,5-tetrachloroben-
zene (Klraly et al., 1979) each caused statistically significant Increases
In the frequency of chromosomal aberrations, but neither study reported the
ambient atmospheric concentration. Thus, these two chlorobenzenes are clas-
togenlc, but the critical exposure concentration Is not known.
13.5. FACTORS INFLUENCING HEALTH HAZARD ASSESSMENT
13.5.1. Exposure. For an Individual or a population, exposure to poten-
tially toxic substances occurs on two levels. The first 1s exposure to
ambient environmental levels which occurs through food, drinking water and
air. Physiologic exposure 1s the second and more Important level and occurs
after the compound has been absorbed and 1s 1n a position to Interact
directly with critical cellular components. This Interaction 1s the basis
for toxlcologlc effects.
Chlorinated benzenes 1n the environment are resistant to blotransforma-
tlon and degradation and are, therefore, ecologically persistent compounds.
At the level of the Individual organism, these compounds are biologically
persistent because of their affinity for fatty tissues and their slow rate
of blotransformatlon or elimination (see Section 5.3.). Thus, biological
persistence and bloaccumulatlon 1n nonhuman organisms Increase the likeli-
hood of human exposure. Tables 13-15 and 13-16 present some useful proper-
ties and trends of chlorinated benzenes which Illustrate the differences
that exist between the chlorinated benzenes Isomers and their potential for
human exposure.
1836A 13-40 03/30/84
-------
CD
00
CTi
3>
TABLE 13-15
Comparison of Chemical and Physical Properties of Chlorinated Benzenes
to
i
-fs.
O
CO
CO
o
CO
Chemical
Monochlorobenzene
Olchlorobenzene
1,2-
1,3-
1,4-
Trlchlorobenzene
1.2,3-
1,2,4-
1,3.5-
Tetrachlorobenzene
1,2,3,4-
1.2,3,5-
1,2,4,5-
Pentachlorobenzene
Hexachlorobenzene
Molecular
Weight*
112.56
147.01
147.01
147.01
181.46
181.46
181.46
215.90
215.90
215.90
250.34
284.76
Melting
Point (°C)a
-45.6
-17.0
-24.7
53.1
52.6
16.95
63.4
47.5
54.5
139.5
86
230
Boiling
Point (°C)a
132
180.5
173
174
221
213.5
208.4
254
246
246
277
3229
Density
g/mc (20°C)a
1.1058
1.3048
1.2828 (25)
1.2475
1.69
1.4542
1.3865 (64)
NA
NA
1.858 (22)
1.8342 (16.5)
1.569 (23)
Log P°a
2.84
3.38
3.38
3.39
4.1
4.12
NA
NA
NA
4.93
5.63
5.8
Volatility 1n
Vapor Pressure
MM Hg at 25°CD
11.8
1.28
1.89
1.0
Likely to be present as
h vapor In ambient air
0.07
0.29
0.15
0.04
0.07
0.05
~0
Not likely to be present
1n ambient air — more
likely to be present 1n
condensed state 1n soil
etc.
1.68x10-''
Increasing trend
''Decreasing trend
NA = Not available
P° = Partition coefficient at 25°C
-------
CO
CO
TABLE 13-16
Comparison of Chlorinated Benzenes BCF and Water Concentrations
CO
CO
v^
IV)
Chemical
Monoch lorobenzene
Dlchlorobenzene
1.2-
1.3-
1.4-
TMchlorobenzene
1.2,3-
1.2,4-
1.3,5-
Tetrachlorobenzene
1.2,3.4-
1,2.3.5-
1.2,4,5-
Pentachlorobenzene
Hexachlorobenzene
BCFa
(rainbow trout)
46
270-560
420-740
370-720
1,200-2,600
890-3,200
1,800-4,100
5,200-12,000
NA
5,300-13,000
13,000-20,000
5,500-20,000
Mean Chlorobenzene
Concentrations 1n
Drinking Waterb
(ng/l)
NA
3
1
13
0.1
2
<0.1
0.3
<0.05
0.2
0.04
0.1
Chlorinated Benzenes 1n
Various Wastewaters
Mean Concentration
(v9/l)
667
141
21
79
NA
161
NA
NA
NA
NA
NA
NA
Increasing trend
^Decreasing trend
BCF = B1oconcentrat1on factor; NA = not available
-------
Although toxic effects 1n humans have not been directly related to
ambient chlorinated benzene exposure, H 1s apparent from the residue levels
1n human tissues that humans receive physiologic exposures to the chlori-
nated benzenes (see Section 4.3.5.). A comparison of human ambient exposure
levels and tissue concentrations confirms that humans bloaccumulate chlori-
nated benzenes (Burn et al., 1974; Currier et al., 1980). Prolonged
physiologic exposure and the uncertainty of the toxic effects of chronic
low-dose exposure to the chlorinated benzenes Increase the concern for human
exposures resulting from ambient levels of these substances.
The large number of locations at which chlorinated benzenes have been
detected Indicate their ubiquity 1n the environment and 1s a reflection of
their annual production volume, release rate, end uses (Sections 4.1.-4.3.),
and their environmental transport and fate (Sections 5.1.-6.3.). Human
exposure to these ambient concentrations depends on the chlorobenzene
concentration 1n, and absorption efficiency from, air, drinking water or
food. The relative contribution of each medium to the total human exposure
was estimated from monitoring data for several areas of the United States;
the limitations of these estimates are discussed 1n Section 4.4. The
estimated yearly exposures to the chlorinated benzenes from air are shown 1n
Table 13-17 and are based on the data for each chlorobenzene shown 1n Table
1-8. The available data Indicate that human exposure to chlorinated ben-
zenes through Inhalation may be greater than Ingestion exposure either
through drinking water or through foods. The relative contribution of food
to human exposure 1s less certain because food has not been extensively
monitored for chlorinated benzene residues; two studies estimated annual
hexachlorobenzene exposures of 0.026 mg/year and 0.145 mg/year, respectively
(IARC, 1979).
1836A 13-43 03/30/84
-------
TABLE 13-17
Estimated Yearly Exposure to Several
Chlorinated Benzenes Via Inhalation
Exposure (mq/yr)
Chemical
Monochlorobenzenes
1 ,2-D1chlorobenzene
1 ,3-D1chlorobenzene
1 ,4-D1chlorobenzene
Tr Ichlorobenzenes
Tetrachlorobenzenes
Mean Ambient Con-
centration (ng/m3)*
3087
1142
571
1563
136
3502
Adult
Man
25.9
9.6
4.8
13.1
1.1
29.4
Adult
Woman
23.8
8.8
4.4
12.0
1.0
27.0
Child
(10 yr)
17.0
6.3
3.1
8.6
0.7
19.3
Infant
(1 yr)
4.3
1.6
0.8
2.2
0.2
4.9
*Mean levels obtained from Table 4-8
1836A
13-44
3/28/84
-------
This paucity of data for food, however, does not preclude this medium as
a significant human exposure route. Trout from the Great Lakes, for
example, had detectable levels of all of the chlorobenzenes except mono-
chlorobenzene (Oliver and N1col, 1982), and H 1s conceivable that other
animals used as food sources also have tissue residues of chlorobenzenes.
13.6. REGULATIONS AND STANDARDS
The chlorinated benzenes are regulated under numerous United States and
foreign statutes. These have been grouped according to the type of activity
or medium being controlled.
13.6.1. Occupational Standards.
13.6.1.1. HONOCHLOROBENZENE -- The current OSHA standard for mono-
o
chlorobenzene levels 1n the workplace 1s 75 ppm (350 mg/m ). This thres-
hold limit value (TLV), established 1n 1974, 1s not to be exceeded for an
8-hour time weighted average (TWA) for an employee's exposure In any 8-hour
shift of a 40-hour workweek (29 CFR 1910). This standard 1s Identical to
those recommended by the American Conference of Governmental Industrial
Hyg1en1sts (ACGIH, 1982). Occupational standards for monochlorobenzene have
also been established 1n four foreign countries. These are presented 1n
Table 13-18.
The Interagency Testing Committee (ITC) designated monochlorobenzene a
TSCA Section 4(e) priority chemical 1n Us Initial Report to the Administra-
tor of EPA (44 FR 70666). Additionally, all manufacturers and producers of
monochlorobenzene were required to report exposure, production and use
Information to EPA's Office of Toxic Substances in the form of a Preliminary
Assessment Information Manufacturers Report. The deadline for submission
was November 19, 1982 (40 CFR 712).
1836A 13-45 3/26/84
-------
TABLE 13-18
Occupational Standards for Monochlorobenzene*
TLV
Year
o
Country ppm mg/m Adopted
USSR 11 50 1972
German Democratic Republic — 50 1973
Czechoslovakia — 200 1969
Federal Republic of Germany 50 230 1974
USA 75 350 1974
*Source: Verschueren, 1977
1836A 13-46 3/26/84
-------
13.6.1.2. OICHLOROBENZENES — The OSHA standard for 1,2-dlchloroben-
3
zene 1n the workplace 1s set at a celling of 50 ppm (300 mg/m ). Levels
1n the workplace are at no time permitted to exceed this value (39 FR, No.
125). The 1982 ACGIH TLV for 1,2-d1chlorobenzene 1s Identical (ACGIH,
1982). Foreign standards for occupational exposure to 1,2-d1chlorobenzene
are shown 1n Table 13-19.
In 1978, NIOSH classified 1,2-d1chlorobenzene as a Group II pesticide (a
pesticide that poses "adverse acute health risks at moderate doses") and
recommended criteria for standards for occupations 1n pesticide manufactur-
ing and formulating (NIOSH, 1978). These standards rely on engineering
controls, work practices and medical surveillance programs, rather than
workplace air limits, to protect workers from adverse effects of pesticide
exposure 1n pesticide manufacturing and formulating. NIOSH specifically
chose not to establish scientifically valid environmental (workplace air)
limits for pesticides (except those already promulgated) because exposure
via other routes, especially dermal, had proven to be of critical Importance
for many pesticides and NIOSH believed that "Immediate action" was needed to
protect workers 1n pesticide manufacturing and formulating plants (NIOSH,
1978).
The current OSHA standard for 1,4-d1chlorobenzene 1n the workplace 1s a
TLV of 75 ppm, 450 mg/m3 (39 FR, No. 125). In addition to recommending a
TLV Identical to the OSHA standard, ACGIH has recommended a short-term
exposure limit (STEL), the maximum concentration allowable 1n a !5-m1nute
3
period, of 110 ppm (675 mg/m ) for 1,4-d1chlorobenzene {ACGIH, 1982).
NIOSH has also classlfed 1,4-d1chlorobenzene as a Group II pesticide and
recommended criteria for workplace standards 1n pesticide manufacturing and
formulating plants {NIOSH, 1978). Foreign standards for occupational expo-
sure to 1,4-d1chlorobenzene are presented 1n Table 13-20.
1836A 13-47 3/26/84
-------
TABLE 13-19
Occupational Standards for l,2-D1chlorobenzenea
Level
Country
(Standard)
ppm
mg/m3
Year
Adopted
USSR (TLV)b
German Democratic Republic (TLV)
USA (MAC)C
Federal Republic of Germany (TLV)
50
50
20
150
300
300
1972
1973
1974
1974
aSource: Verschueren, 1977
threshold limit value
cMax1mum allowable concentration
1836A
13-48
3/26/84
-------
TABLE 13-20
Occupational Standards for 1,4-D1chlorobenzene*
Country
USSR
German Democratic Republic
USA
Federal Republic of Germany
TLV
ppm mg/m3
20
200
75 450
75 450
Year
Adopted
1972
1973
1974
1974
*Source: Verschueren, 1977
1836A 13-49 3/26/84
-------
There are no occupational workplace standards, either United States or
foreign, for 1,3-d1chlorobenzene. However, dlchlorobenzenes (no Isomer
specified) were designated by the ITC as TSCA Section 4(e) priority chemi-
cals (44 FR 70666). Separate Preliminary Assessment Information Manufac-
turers Reports on 1,2-, 1,3- and 1,4-d1chlorobenzene were to be submitted to
EPA by November 19, 1982 (40 CFR 712).
13.6.1.3. TRICHLOROBENZENES — There are no United States workplace
standards for the trlchlorobenzenes.
3
The ACGIH has recommended a celling of 5 ppm (40 mg/m ) for 1,2,4-
trichlorobenzene (ACGIH, 1982), and NIOSH classified 1t as a Group III
pesticide. Group III pesticides are less toxic than Group II pesticides and
the recommended criteria for workplace standards are less stringent than
those recommended for Group II pesticides (NIOSH, 1978). The British
Journal of Industrial Medicine reported a provisional operational limit of
25 ppm for 1,2,4-trichlorobenzene (Verschueren, 1977). The 1971 TLV for
1,2,3-trichlorobenzene is 1.3 ppm [10 mg/m3 (n.s.i.)] for the USSR
(Verschueren, 1977).
Trlchlorobenzenes have been designated by the ITC as TSCA Section 4(e)
priority chemicals (44 FR 70666). Preliminary Assessment Information Manu-
facturers Reports were to be submitted to the EPA Office of Toxic Substances
by November 19, 1982, for each of the trlchlorobenzenes (40 CFR 712).
13.6.1.4. TETRACHLOROBENZENES AND PENTACHLOROBENZENE — There are no
occupational workplace standards or recommended criteria for standards,
United States or foreign, for the tetrachlorobenzenes or pentachlorobenzene.
These chlorobenzenes have been designated as TSCA Section 4(e) priority
chemicals (44 FR 70666). Preliminary Assessment Information Manufacturers
Reports were required on 1,2,3,4-tetra-, 1,2,3,5-tetra- and 1,2,4,5-tetra-
chlorobenzene and pentachlorobenzene (40 CFR 712).
1836A 13-50 3/26/84
-------
13.6.1.5. HEXACHLOROBENZENE -- Workplace standards have not been
established 1n the United States. The USSR has established a TLV of 0.08
3
ppm (0.9 mg/m ) (Verschueren, 1977). NIOSH classified hexachlorobenzene
as a Group II pesticide and recommended criteria for standards (NIOSH, 1978).
13.6.2. Transportation Regulations. The Department of Transportation
(DOT), the Coast Guard and the Departments of Commerce and Energy regulate,
1n varying degrees, the transport of the chlorinated benzenes.
All of the chlorinated benzenes are regulated under the Hazardous
Material Transportation Act (HMTA) as amended by the Comprehensive Environ-
mental Response Compensation and Liability Act (CERCLA), I.e., "Superfund"
Act (49 CFR 172.101, 46 FR 17738). The HMTA, administered by DOT, specifies
the requirements to be observed in the preparation for interstate shipment
and transport of hazardous materials (46 CFR 171-179). CERCLA further
classified the chlorinated benzenes as hazardous substances and provides
that common carriers of hazardous substances may be held liable for releases
of hazardous substances 1n amounts equal to or greater than the reportable
quantity (RQ). The RQs for mono-, 1,2-di- or 1,4-dichlorobenzene are set at
100 pounds (45.4 kg) (49 CFR 172.101). RQs for the remaining chlorinated
benzenes have been set at 1 pound pending establishment of different RQs by
EPA (46 CFR 17738).
DOT has designated monochlorobenzene as a flammable liquid. The maximum
net quantity permitted 1n one package for transport by passenger carrying
aircraft or rallcar has been set at 1 quart, while the maximum net quantity
for cargo aircraft has been set at 10 gallons/package (49 CFR 172.101).
The U.S. Coast Guard regulates the transport of hazardous materials
while aboard vessels. Title 46, Part 150, specifies the compatibility of
cargoes and operating requirements for bulk liquid hazardous waste cargoes;
1836A 13-51 03/30/84
-------
I.e., monochlorobenzene, dlchlorobenzene (no Isomer specified) and 1,2,4-
trlchlorobenzene (46 CFR 150). Part 153 prescribes the safe handling
procedures for self-propelled vessels carrying hazardous liquids; I.e.,
mono- and dlchlorobenzene (no Isomer specified) (46 CFR 153). Part 151
details the minimum requirements for unmanned tank barges carrying bulk
dangerous cargoes; I.e., monochlorobenzene (46 CFR 151).
The International transport of hazardous materials 1s regulated by the
International Maritime Dangerous Goods Code (IMCO) and administered by DOT
1n this country. Mono-, l,2-d1- and 1,4-dlchlorobenzene are regulated under
the IMCO code (46 FR 29392, 49 CFR 172.102).
The export of the chlorobenzenes (I.e., mono-, l,2-d1-, l,4-d1, 1,2,3-
tr1-, 1,2,4-tM- and hexachlorobenzene) 1s regulated by the DOT via the
departments use of the Commodity Control List (15 CFR 399). The DOE
regulates the Import of oil and petrochemicals, and mono-, d1- and tetra-
chlorobenzene (no Isomers specified) are classified as petrochemicals under
the authority of the 011 Import Regulations (10 CFR 213).
13.6.3. Solid Waste Regulations. Under the Solid Waste Disposal Act as
amended by the Resources Conservation and Recovery Act (RCRA), EPA has
designated mono-, l,2-d1~, l,3-d1~, l,4-d1-, 1,2,4,5-tetra-, penta- and
hexachlorobenzene as hazardous wastes (40 CFR 261.33); subject to the
disposal and permit regulations of Title 40 Code of Federal Regulations,
Parts 262-265 and Parts 122-124 (40 CFR 261). All of the chlorinated
benzenes are designated as hazardous constituents of hazardous wastes from
specific sources subject to RCRA disposal regulations (40 CFR 261.32).
Table 13-21 shows these specific wastes 1n relation to the chlorinated
benzenes. Monochlorobenzene and 1,2-dichlorobenzene, as spent halogenated
solvents, and their still bottoms from the recovery of these solvents, are
1836A 13-52 3/26/84
-------
TABLE 13-21
The Chlorinated Benzenes as Constituents
of Hazardous Wastes from Specific Sources*
EPA Hazardous
Waste No.
Hazardous Waste
Hazard
Constituent
KOI 5
K016
K018
K030
K042
K085
K105
Still bottoms from the distillation
of benzyl chloride
Heavy ends or distillation residues
from the production of carbon
tetrachlorlde
Heavy ends from the fractlonatlon
column 1n ethyl chloride production
Column bottoms or heavy ends from
the combined production of tr1-
chloroethylene and perchloroethylene
Heavy ends or distillation residues
from the distillations of tetra-
chlorobenzene 1n the production of
the 2,3,5- Isomer
Distillation or fractlonatlon column
bottoms from the production of
chlorobenzene
Separated aqueous stream from the
reactor product washing step 1n the
production of chlorobenzene
Monochlorobenzene
Hexachlorobenzene
Hexachlorobenzene
Hexachlorobenzene
l,2-D1chloro- and
hexachlorobenzene
Dlchlorobenzenes,
tMchlorobenzenes,
tetrachlorobenzenes,
pentachlorobenzene,
hexachlorobenzene
Monochlorobenzene,
dlchlorobenzenes
*Source: 40 CFR 261.32
1836A
13-53
3/26/84
-------
also regulated for disposal under RCRA (Hazardous Waste No. F002) provided
that the combined concentrations of the spent solvent 1n the resulting
mixture 1s no greater than 25 ppm (46 PR 56582, 40 CFR 261.31).
13.6.4. Food Tolerances. Food tolerances have been established for mono-
chlorobenzene and hexachlorobenzene.
13.6.4.1. MONOCHLOROBENZENE — Monochlorobenzene 1s exempted from the
requirement of a tolerance when used 1n accordance with good agricultural
practices as an Ingredient 1n pesticide formulation applied to growing crops
only. Permitted uses are as a solvent or cosolvent 1f monochlorobenzene
contains not more than 1% Impurities. Under FIFRA, use of monochlorobenzene
1s prohibited after edible parts of plants begin to form. The grazing of
livestock 1n treated areas 1s prohibited within 48 hours after application
[40 CFR 180.1001(d)].
The FDA permits the use of polysulfone resins and polycarbonate resins
as articles or components of articles for use 1n producing or holding food.
These resins are permitted to contain 500 ppm of monochlorobenzene as a
residual solvent 1n finished (basic) resin (21 CFR 177.1580, 21 CFR
177.2500). Monochlorobenzene as a component of adheslves used In the
packaging of food 1s also regulated by FDA (21 CFR 175.105).
13.6.4.2. HEXACHLOROBENZENE — USDA regulates the use of hexachloro-
benzene as a seed treatment for the control of wheat bunt (smut) under the
Federal Seed Act (7 CFR 201).
13.6.5. Water Regulations. Under Section 311(b)(2)(A) of the Federal
Water Pollution Control Act, EPA designated monochlorobenzene, dlchloroben-
zene (no Isomer specified), l,2-d1- and 1,4-d1chlorobenzene as hazardous
substances (40 CFR 116.4) and established an RQ of 100 pounds (45.4 kg) for
these chlorinated benzenes (40 CFR 117.3). Discharges equal to or greater
1836A 13-54 3/26/84
-------
than the RQ Into or upon United States waters are prohibited unless the
discharge 1s 1n compliance with applicable permit programs (40 CFR 117.11).
Under the Clean Water Act, Section 307(a), EPA has designated chlori-
nated benzenes (other than dlchlorobenzene) and dichlorobenzenes (all
Isomers) as toxic pollutants, I.e., priority pollutants (40 CFR 401.15).
Effluent limitation guidelines, new source performance standards, and pre-
treatment standards have been developed or will be developed for the prior-
ity pollutants for 21 major Industries. Specific definitions for classes
and categories are set forth 1n 40 CFR, Parts 402 through 699.
Under the Clean Water Act, Ambient Water Quality Criteria for chlori-
nated benzenes have been developed (U.S. EPA, 1980a,b). These are summar-
ized 1n Tables 13-22 and 13-23. The USSR 1n 1971 established a drinking
water standard for monochlorobenzene of 0.02 mg/l, and an organoleptlc
limit for l,2-d1- and 1,4-d1chlorobenzene has been set at 0.002 mg/s.
(Verschueren, 1977).
13.6.6. A1r Regulations. Ambient air quality standards for the chlori-
nated benzenes have not been established 1n the United States. Maximum
1mm1ss1on concentration (MIC) and maximum emission concentration (MEC)
standards have been established 1n several European countries for mono-
chlorobenzene, 1,2- and 1,4-d1chlorobenzene.
Maximum emm1ss1on concentration standards; I.e., ambient air quality
standards, are used for calculating the minimum stack heights permitted by
law. Dispersion of emitted compounds must be such that the addition of
these compounds to ground level concentrations does not result 1n the
ambient air quality standard being exceeded more frequently than the allowed
percentage. The MEC 1s the maximum concentration of a specific pollutant in
emitted gases. MECs are derived from ambient air quality standards by
taking into account the dispersion phenomena (Verschueren, 1977).
1836A 13-55 3/28/84
-------
TABLE 13-22
Ambient Water Quality Criteria
for Chlorinated Benzenes—Aquatic L1fea
Chlorinated
Aquatic Life Benzenes'3 Dlchlorobenzenes
Freshwater aquatic life
Acute toxldty 250 ug/lc 1120 yg/&c
Chronic toxldty —d«e 763 yg/8.c
Saltwater aquatic life
Acute toxldty 160 yg/fcC 1970 pg/fcC
Chronic toxldty 129 yg/!lc —d
aSource: U.S. EPA, 1980a,b
^Includes all of the chlorinated benzenes except the dlchlorobenzenes
cTox1dty would occur at lower concentrations among species that are more
sensitive than those tested.
dNo data available
6Tox1c1ty occurs at concentrations as low as 50 yg/8, for fish spedes
exposed for 7.5 days.
1836A 13-56 3/26/84
-------
CD
CO
TABLE 13-23
Ambient Water Quality Criteria for the
Chlorinated Benzenes for the Protection of Human Health3
Compound
From Toxic Properties
Ingested Through:
Based on
Available:
Water and
Contaminated
Aquatic Organisms
Contaminated
Aquatic
Organisms Alone
Tox1c1ty
Data
Organoleptlc
Data
From the
Potential:
Carcinogenic
Effects
CO
I
tn
Monochlorobenzene
Dlchlorobenzenes
Trlchlorobenzenes
1,2,4,5-Tetra-
cnlorobenzene
Pentachlorobenzene
Hexachlorobenzene
488 yg/9.
20 vg/lb
400
__
38 vg/l
74 yg/8.
2.6 mg/8.
c
48 yg/8.
85 vg/8.
CO
aSource: U.S. EPA, 1980a,b
bOrganolept1c data as a basis for establishing a water quality criteria have limitations and have no
demonstrated relationship to potential adverse human health effects.
C0ue to Insufficient data, a criterion was not derived.
dBased on the nonthreshold assumption, however, a zero level may not be attainable at the present time
and, therefore, levels that may result 1n Incremental Increases of cancer risk of the lifetime were esti-
mated at 10~5, 10~6 and 10~7. The corresponding recommended criteria are 7.2 ng/8., 0.72 ng/a,
and 0.072 ng/a., respectively; 1f estimates are for consumption of aquatic organisms only, the levels
are 7.4 ng/il, 0.74 ng/8. and 0.074 ng/8..
-------
13.6.6.1. MONOCHLOROBENZENE -- Ambient air quality standards for
monochlorobenzene have been established 1n five countries and are shown 1n
Table 13-24. In addition, MEC limits have been established 1n the Federal
Republic of Germany; should emissions exceed 3 kg/hour, then a concentration
3
of 150 mg/m cannot be exceeded (Verschueren, 1977).
13.6.6.2. DICHLOROBENZENES -- Maximum emission concentration limits
for 1,2- and 1,4-d1chlorobenzene have been established 1n the Federal
Republic of Germany. The MEC limits set were the same as those established
for monochlorobenzene: 150 mg/m3 1f emissions are >3 kg/hour
(Verschueren, 1977).
1836A 13-58 3/26/84
-------
TABLE 13-24
Maximum Imm1ss1on Concentration Standards for Monochlorobenzene*
Country
USSR
German Democratic
Republic
Bulgaria
Federal Republic of
Germany-VDI (Assoc.
of German Engineers)
Yugoslavia
mg/m3
0.100
0.3
0.1
15.0
0.1
MICS
Average
ppm Time
20 m1n
30 m1n
0.02 20 m1n
3.0 30 m1n
0.02 30 m1n
mg/m3
0.100
0.1
0.1
5.0
0.1
MIC1
Average
ppm Time
24 hr
24 hr
0.02 24 hr
1.0 30 m1n
0.02 24 hr
*Source: Verschueren, 1977
1836A 13-59 3/26/84
-------
14. REFERENCES
Abbott, D.C., G.B. Collins, R. Gouldlng and R.A. Hoodless. 1981. Organo-
chloMne pesticide residues 1n human fat 1n the United Kingdom, 1976-7. Br.
Med. J. 283: 1425-1428.
ACGIH (American Conference of Governmental Industrial Hyg1en1sts). 1982.
Threshold Limit Values for Chemical Substances 1n Work A1r Adopted by ACGIH
for 1982. Cincinnati, OH. ISBN: 0-936712-39-2.
Adams, J.R. and R. Rodrlquez-Kabana. 1976. The effects of 1,2,4,5-tetra-
chlorobenzene on plant parasitic and free-living nematodes. J. Alabama
Acad. Sd. 47: 134. (Abstr.)
Albro, P.W. and R. Thomas. 1974. Intestinal absorption of hexachloroben-
zene and hexachlorohexane Isomers 1n rats. Bull. Environ. Contam. Toxlcol.
12(3): 289-294.
Allied Chemical Corporation. 1973. Product data sheets - monochloroben-
zene, o-d1chlorobenzene, p-d1chlorobenzene. MorMstown, NJ. (CHed 1n:
U.S. EPA, 1980a)
Ameen, O.A., A.O. Day and K.C. Hamilton. 1960. Effect of 1,2,4,5-tetra-
chlorobenzene on the germination and seeding vigor of barley, oats, and
wheat. Agron. J. 52: 87-89.
1837A 14-1 03/29/84
-------
Anbar, M. and P. Neta. 1967. A compilation of specific bimolecular rate
constants for the reactions of hydrated electrons, hydrogen atoms and
hydroxyl radicals with Inorganic and organic compounds 1n aqueous solution.
Int. J. Appl. Radlat. Isotop. 18: 493-523.
Anderson, K.J., E.G. Lelghty and H.T. Takahashl. 1972. Evaluation of
herbicides for possible mutagenic properties. J. Agric. Food Chem. 20(3):
649-656.
Ariyoshi, T., M. Arakaki, K. Ideguchi and Y. Ishizuka. 1974. Relation
between chemical structure and drug metabolizing enzyme activities. Proc.
Symp. Drug Metab. Action, p. 187-194.
Ariyoshi, T., K. Ideguchi, Y. Ishizuka, K. Iwasaki and M. Arakaki. 1975a.
Relationship between chemical structure and activity. I. Effects of the
number of chlorine atoms 1n chlorinated benzenes on the components of
drug-metabolizing system and the hepatic constituents. Chem. Pharm. Bull.
23(4): 817-823.
Ariyoshi, T., K. Ideguchi, K. Iwasaki and M. Arakaki. 1975b. Relationship
between chemical structure and activity. II. Influences of Isomers in
dlchlorobenzene, trichlorobenzene, and tetrachlorobenzene on the activities
of drug-metabolizing enzymes. Chem. Pharm. Bull. 23(4): 824-830.
1837A 14-2 03/29/84
-------
AMyoshl, T., K. Ideguchl, K. Iwasakl and M. Arakakl. 1975c. Relationship
between chemical structure and activity. III. Dose-response or time-course
of Induction 1n mlcrosomal enzymes following treatment with 1,2,4-tMchloro-
benzene. Chem. Pharm. Bull. 23(4): 831-836.
Arlyoshi, T., M. Eguchl, Y. Murakl, M. Yasumatsu, N. Suetsugu and K.
AMzono. 1981. Effects of chlorinated benzenes on the activities of 6-
aminolevul1n1c add synthetase and heme oxygenase and on the content of
hemoproteln 1n the Hver of rats. J. Pharm. Dyn. 4(1): 69-76.
Armltage, P. and R. Doll. 1954. The age distribution of cancer and a
multistage theory of cardnogenesls. Br. J. Cancer. 8: 1-12.
Arnold, O.L. 1983. Personal communication to Murial M. Llppman, ERNACO,
Inc., Silver Springs, MD.
Arnold, D.L. 1984. Personal communication to Murial M. Llppman, ERNACO,
Inc., Silver Springs, MD.
Arnold, D.L., C.A. Moodle, S.M. Charbonneau, et al. 1983. Long-term tox-
1c1ty of hexachlorobenzene 1n the rat. (In preparation)
Atlas, E. and C.S. G1am. 1981. Global transport of organic pollutants:
Ambient concentration 1n the remote marine atmosphere. Science. 211(4478):
163-165.
1837A 14-3 03/29/84
-------
Ausmus, B.S., S. Klmbrough, D.R. Jackson and S. Llndberg. 1979. The
behavior of hexachlorobenzene 1n pine forest microcosms: Transport and
effects on soil processes. Environ. Pollut. 20(2): 103-112.
Azouz, W.M., O.V. Parke and R.T. Williams. 1955. Studies 1n detoxlcatlon.
The metabolism of halogenobenzenes. Ortho and para-dlchlorobenzenes. B1o-
chem. J. 59(3): 410-415.
Bailey, J., V. Knauf, W. Mueller and W. Hobson. 1980. Transfer of hexa-
chlorobenzene and polychlorlnated blphenyls to nursing Infant rhesus mon-
keys: Enhanced toxldty. Environ. Res. 21(1): 190-196.
Bakken, A.F. and M. Se1p. 1976. Insecticides 1n human breast milk. Act.
Paedlat. Scand. 65: 535.
Ballschmlter, K. and C. Scholz. 1980. M1crob1al decomposition of chlori-
nated aromatic substances. VI. Formation of dlchlorophenols and dlchloro-
phyrocatechol from dlchlorobenzenes 1n a mlcromolar solution by Pseudomonas
species. Chemosphere. 9(7-8): 457-467.
Banerjee, S., S.H. Yalkowsky and S.C. Valvanl. 1980. Water solubility and
octanol/water partition coefficients of organlcs. Limitations of the solu-
bility-partition coefficient correlation. Environ. Sc1. Technol. 14(10):
1227-1229.
1837A 14-4 03/29/84
-------
Barbehenn, K.R. and W.L. Relchel. 1981. OrganochloMne concentrations 1n
bald eagles: Brain/body I1p1d relations and hazard evaluation. J. Toxlcol.
Environ. Health. 8(1-2): 325-330.
Barkley, J., J. Bunch, J.T. Bursey, et al. 1980. Gas chromatography mass
spectrometry computer analysis of volatile halogenated hydrocarbons 1n man
and his environment. A multimedia environmental study. Blomed. Mass
Spectrom. 7(4): 139-147.
Barquet, A., C. Morgade and C.O. Pfaffenberger. 1981. Determination of
organochlorlne pesticides and metabolites 1n drinking water, human blood
serum, and adipose tissue. J. Toxlcol. Environ. Health. 7(3-4): 469-479.
Barrows, M.E., S.R. Petrocelll, K.J. Macek and J.J. Carroll. 1978. Blocon-
centratlon and elimination of selected water pollutants by blueglll sunflsh
(Lepomls macrochlrus). Am. Chem. Soc., D1v. Environ Chem. 18: 345-346.
Barrows, M.E., S.R. Petrocelll, K.J. Macek and J.J. Carroll. 1980. Blocon-
centratlon and elimination of selected water pollutants by blueglll sunflsh
(Lepomls macrochlrus). Dyn. Exposure Hazard Assess. Toxic Chem. (Pap.
Symp.). p. 397-392.
Bartha, P. and A.C. Marlnucd. 1979. B1odegradat1on of 1,2,3- and
1,2,4-tr1chlorobenzene 1n soil and 1n liquid enrichment culture. Appl.
Environ. M1crob1ol. 38(5): 811-817.
1837A 14-5 03/29/84
-------
Beall, M.L. 1976. Persistence of aerially applied hexachlorobenzene on
grass and soil. J. Enlvorn. Qual. 5(4): 367-369.
Bechard, M. 1981. DDT and hexachlorobenzene residues 1n Southeastern Wash-
ington Swalnson's hawks. Bull. Environ. Contam. Toxlcol. 26(1): 248-253.
Beck, J. and K.E. Hansen. 1974. The degradation of qulntozene, penta-
chlorobenzene, hexachlorobenzene, and pentachloroanlUne 1n soil. Pest.
Sd. 5(1): 41-48.
Bellar, T.A., W.L. Budde and J.W. Elchelberger. 1979. The Identification
and measurement of volatile organic compounds 1n aqueous environmental
samples. In_; Monitoring Toxic Substances, D. Schuetzle, Ed. Am. Chem. Soc.
Symp. Ser. No. 94, 174th Meet. ACS, Chicago, IL, August 31, 1977. ACS,
Washington, DC.
Bldleman, T.F. 1981. Interlaboratory analysis of high molecular weight
organochlorlnes 1n ambient air. Atmos. Environ. 15(4): 619-624.
Biggs, D.C., R.G. Rowland and C.F. Wurster. 1979. Effects of tMchloro-
ethylene, hexachlorobenzene and polychlorlnated blphenyls on the growth and
cell size of marine phytoplankton. Bull. Environ. Contam. Toxlcol.
21(1-2): 196-201.
Billings, W.N. and T.F. Bldleman. 1980. Field comparison of polyurethane
foam and Tenax-GC resin for high-volume air sampling of chlorinated hydro-
carbons. Environ. Sc1. Technol. 14(6): 679-683.
1837A 14-6 03/29/84
-------
B1rge, W.J., J.A. Black and D.M. Bruser. 1979. Toxlcity of organic chemi-
cals to embryo-larval stages of fish. Prepared by Thomas Hunt Morgan School
of Biological Sciences under Contract No. 68-01-4321. OTS, U.S. EPA, Wash-
ington, DC. EPA 560/11-79-007. NTIS PB 80-101637.
Bjerk, J.E. and E.M. Brevik. 1980. Organochlorlne compounds 1n aquatic
environments. Arch. Environ. Contam. Toxlcol. 9(6): 743-750.
Black, W.D., V.E.O. Valll, J.A. Ruddlck and D.C. Vllleneuve. 1983. The
toxldty of three trlchlorobenzene isomers 1n pregnant rats. The Tox1-
cologlst. 3(1): 30. (Abstr.)
Blackwood, T.R. and T.6. S1pes. 1979. Status assessment of toxic chemi-
cals: Hexachlorobenzene. ORO, U.S. EPA, Cincinnati, OH. EPA 600/2-79-210g.
Bleavlns, M.R., W.J. Breslln, R.J. Aulerlch and R.K. Ringer. 1982. Excre-
tion and placental and mammary transfer of hexachlorobenzene 1n the European
ferret (Mustela putorlus furo). J. Toxlcol. Environ. Health. 10: 929-940.
Blekkenhorst, G.H., R.S. Day and L. Eales. 1980. The effect of bleeding
and Iron administration on the development of hexachlorobenzene-lnduced rat
porphyrla. Int. J. Blochem. 12(5-6): 1013-1017.
Blus, L.J., T.G. Lamont and B.S. Burkett, Jr. 1979. Effects of organo-
chlorlne residues on eggshell thickness, reproduction and population status
of brown pelicans (Pelecanus occidental is) in South Carolina and Florida,
1969-76. Pest. Monit. J. 12(4): 172-184.
1837A 14-7 03/29/84
-------
Blus, L.J., O.H. Pattee, C.J. Henny and R.M. Prouty. 1983. Short communi-
cations. First record of chlordane-related mortality 1n wild birds. J.
W1ldl. Manage. 47(1): 196-198.
Boger, A., G. Koss, W. Koransky, R. Naumann and H. Frenzel. 1979. Rat
Hver alterations after chronic treatment with hexachlorobenzene. Vlrchows
Arch. [Path Anat.] 382(2): 127-137.
Bonnet, P., Y. Morele, 6. Raoult, D. Z1ssu and 0. 6rad1sk1. 1982. Deter-
mination of the median lethal concentration of the main aromatic hydro-
carbons 1n rats. Arch. Mai. Prof. 43(4): 261-265. (Fre.)
Bozzelll, J.W. and 8.8. Kebbekus. 1979. Analysis of Selected Volatile
Organic Substances 1n Ambient A1r; Final Report Apr.-Nov. 1978. New Jersey
Oept. Environ. Prot., Trenton, NJ. NTIS PB 80-144694.
BozzelH, J.W., J. Kemp, L. Horgan and B.B. Kebbekus. 1981. Analysis of
ambient air at New Jersey locations for selected volatile organic compounds.
Proc. Ann. Meet., A1r Pollut. Control Assoc. 74(3): 81-47.4. 20 p.
Brady, M.N. and D.S. S1yal1. 1972. Hexachlorobenzene 1n human body fat.
Med. J. Aust. 1: 158-161.
Brandt, I., A. Lyden, P. Slanlna and L. Albanus. 1980. Hexachlorobenzene
(HCB) and some of Its sulfur-containing metabolites: Tissue retention and
excretion routes In mice. Dav. Toxlcol. Environ. Sci., ISS Mech. Toxic.
Hazard Eval. 8: 627-630.
1837A 14-8 03/29/84
-------
Branson, D.R., W.B. Neely and G.E. Blau. 1975. Predicting a bloconcentra-
tlon potential of organic chemicals 1n fish from partition coefficients.
in: Structure-activity Correlations 1n Studies of Tox1c1ty and Bloconcentra-
tlon with Aquatic Organisms, G.D. Velth and D.E. Konasewlch, Ed. Int. Joint
Comm., Windsor, Ontario, p. 99-118.
Braun, W.H., L.Y. Sung, 0.6. Keyes and R.J. Kodba. 1978. Pharmacok1net1c
and toxlcologlcal evaluation of dogs fed 1,2,4,5-tetrachlorobenzene 1n the
diet for two years. J. Toxlcol. Environ. Health. 4: 727-734. (Also publ.
In J. Environ. Pathol. Toxlcol. 2(2): 225-234.)
Brevik, E.M. 1978. Gas chromatographlc method for the determination of
organochloMne pesticides 1n human milk. Bull. Environ. Contam. Toxlcol.
19(3): 281-286.
BMngmann, G. and R. Kuhn. 1980. Comparison of the toxldty thresholds of
water pollutants to bacteria, algae, and protozoa 1n the cell multiplication
Inhibition test. Water Res. 14(3): 231-241.
Brodzlnsky, R. and H.B. Singh. 1982. Volatile organic chemicals 1n the
atmosphere: An assessment of available data. Contract No. 68-02-3452.
Environ. Sc1. Res. Lab., ORO, U.S. EPA, Research Triangle Park, NC.
Brosler, J.S. 1972. A modified static toxldty test and b1o-accumulat1on
of monochlorobenzene 1n rainbow trout. Waste Control. (Unpubl. data)
1837A 14-9 03/29/84
-------
Brown, V.K.H., C. Mu1r and E. Thorpe. 1969. The acute tox1c1ty and skin
Irritant properties of 1,2,4-tr1chlorobenzene. Ann. Occup. Hyg. 12:
209-212.
Brunn, H. and D. Manz. 1982. Contamination of native fish stock by hexa-
chlorobenzene and polychlorlnated blphenyl residues. Bull. Environ. Contam.
Toxlcol. 28(5): 599-604.
Buccafusco, R.J., S.J. Ells and G.A. LeBlanc. 1981. Acute toxldty of pri-
ority pollutants to blueglll (Lepomls macrochlrus). Bull. Environ. Contam.
Toxlcol. 26(4): 446-452.
Buchert, H., S. Blhler, P. Schott, H.P. Roper, H.J. Pachur and K. Ball-
schmlter. 1981. Organochlorlne pollutant analysis of contaminated and
uncontamlnated lake sediments by high resolution gas chromatography.
Chemosphere. 10(8): 945-956.
Burns, J.E. and P.M. Miller. 1975. Hexachlorobenzene contamination: Its
effects 1n a Louisiana population. Arch. Environ. Health. 30: 44-48.
Burns, J.E., P.M. Miller, E.D. Gomes and R.A. Albert. 1974. Hexachloroben-
zene exposure from contaminated DCPA 1n vegetable spraymen. Arch. Environ.
Health. 29: 192-194.
Cabral, J.R.P. 1983. Personal communication to Murlal M. Llppman, ERNACO,
Inc., Silver Springs, MD.
1837A 14-10 03/29/84
-------
Cabral, J.R.P., P. Shublk, T. Mollner and F. RaHano. 1977. Carcinogenic
activity of hexachlorobenzene 1n hamsters. Nature (London). 269: 510-511.
Cabral, J.R.P., T. Mollner, F. Raltano and P. Shublk. 1979. Cardnogenesls
of hexachlorobenzene 1n mice. Int. J. Cancer. 23(1): 47-51.
Calamarl, 0., S. Galassl and F. Settl. 1982. Evaluating the hazard of
organic substances on aquatic life: The paradlchlorobenzene example.
Ecotox. Environ. Safety. 6: 369-378.
Calamarl, D., S. Galassl, F. Settl and M. V1gh1. 1983. Tox1c1ty of
selected chlorobenzenes to aquatic organisms. Chemosphere. 12(2): 253-262.
Cam, C. 1959. Cutaneous porphyMa related to Intoxication. Dlrlm. 34:
11-15. (Tur.)
Cam, P.C. I960. Une nouvelle dermatose }p1d}m1que des enfants. Ann.
Dermatol. Syph1l1ger. 87: 393-397. (Fre.)
Cam, C. and G. Nlgogosyan. 1963. Acquired toxic porphyMa cutanea tarda
due to hexachlorobenzene. J. Am. Med. Assoc. 183(2): 88-91.
Cameron, G.R., J.C. Thomas, S.A. Ashmore, J.L. Buchan, E.H. Warren and A.W.
McKlnney Hughes. 1937. The toxldty of certain chlorine derivatives of
benzene, with special reference to o-d1chlorobenzene. J. Pathol. BacteMol.
44(2): 281-296.
1837A 14-11 03/29/84
-------
Campbell, D.M. and R.J.L. Davidson. 1970. Toxic haemolytlc anemia In preg-
nancy due to a pica for paradlchlorobenzene. J. Obstet. Gynaec. Br.
Cmnwlth. 77: 657. (Cited 1n: U.S. EPA, 1980b)
Carey, A.E., J.A. Gowen, H. Ta1, W.G. Mitchell and G.B. Wlersma. 1979.
Pesticide residue levels 1n soils and crops from 37 states, 1972 - National
Soils Monitoring Program (IV). Pest. Monlt. J. 12(4): 209-229.
Carey, M.A. and E.S. McDonough. 1943. On the production of polyploldy 1n
alHum with paradlchlorobenzene. J. Heredity. 34: 238-241.
Carlson, G.P. 1977a. Halogenated benzenes, effect on xenoblotlc metabolism
and the toxldty of other chemicals. Ann. N.Y. Acad. Scl. 298: 159-169.
Carlson, G.P. 1977b. Chlorinated benzene Induction of hepatic porphyMa.
Exper1ent1a. 33(12): 1627-1629.
Carlson, G.P. 1978. Induction of cytochrome P-450 by halogenated benzenes.
Blochem. Pharmacol. 27(3): 361-363.
Carlson, G.P. 1980. Effects of halogenated benzenes on arylesterase activ-
ity jm vivo and In yUrj). Res. Commun. Chem. Pathol. Pharmacol. 30(2):
361-364.
Carlson, G.P. 1981. Effects of halogenated aromatic compounds on the
metabolism of foreign organic compounds. Health Effects Res. Lab., Cincin-
nati, OH. EPA-600/1-81-010. NTIS PB81-152522.
1837A 14-12 03/29/84
-------
Carlson, G.P. and R.G. Tardlff. 1976. Effect of chlorinated benzenes on
the metabolism of foreign organic compounds. Toxlcol. Appl. Pharmacol. 36:
383-394.
Carlson, G.P., J.D. Dzlezak and K.M. Johnson. 1979. Effect of halogenated
benzenes on acetanHlde esterase, acetanlUde hydroxylase and procalne
esterase 1n rats. Res. Commun. Chem. Pathol. Pharmacol. 25(1): 181-184.
Carpenter, H.M., O.E. Williams, M.C. Henderson, R.C. Bender and D.R. Buhler.
1983. Induction of hepatic drug metabolizing enzymes and hexachlorobenzene
(HCB)-lnduced porphyrla 1n Japanese quail. The Tox1colog1st. 3(1): 115.
(Abstr.)
Chadwlck, R.W., C.J. Chadwlck, J.J. Freal and C.C. Bryden. 1977. Compara-
tive enzyme Induction and Undane metabolism 1n rats pre-treated with var-
ious organochloMne pesticides. Xenob1ot1ca. 7(4): 235-246.
Chlou, C.T. and D.W. Schmeddlng. 1982. Partitioning of organic compounds
1n octanol-water systems. Environ. Sc1. Technol. 16(1): 4-10.
Chu, I., D.C. Vllleneuve, Y.H. Q1n, A. V1au and G.C. Becking. 1983. Tissue
distribution, metabolism and excretion of three tetrachlorobenzene cogeners
1n the rat. Tox1colog1st. 3(1): 104. (Abstr.)
Clark, D.E., G.W. Iv1e and B.J. Camp. 1981a. Effects of dietary hexa-
chlorobenzene on In y1v£ blotransformatlon, residue deposition and elimina-
tion of certain xenoblotlcs by rats. J. Agrlc. Food Chem. 29(3): 600-608.
1837A 14-13 03/29/84
-------
Clark, D.E., M.H. Ellssalde, J.J. Doyle and H.H. Mollenhauer. 1981b.
Interaction of environmental stress and hexachlorobenzene In the laboratory
rat. J. Toxlcol. Environ. Health. 8(1-2): 297-306.
Clark, C.S., C.R. Meyer, P.S. Gartslde, et al. 1982. An environmental
health survey of drinking water contamination by leachate from a pesticide
waste dump 1n Hardeman County, Tennessee. Arch. Environ. Health. 37(1):
9-18.
Clement Associates, Inc. 1979. Third report of the TSCA Interagency Test-
Ing Committee to the Administrator, OTS, U.S. EPA, Washington, DC.
Coate, W.B., W.H. Schoenflsch, T.R. Lewis and W.M. Busey. 1977. Chronic,
Inhalation exposure of rats, rabbits, and monkeys to 1,2,4-tr1chlorobenzene.
Arch. Environ. Health. 32(6): 249-255.
Cohen, J.M., R. Dawson and M. Koketsu. 1981. Extent-of-exposure survey of
rnonochlorobenzene. D1v. Surveillance, Hazard Evaluations and Field Studies,
NIOSH, Cincinnati, OH. ISS DHHS/PUB/NIOSH-81-105. PB 82-183963.
Con1gl1o, W.A., K. Miller and D. MacKeever. 1980. The occurrence of vola-
tile organlcs 1n drinking water. Briefing - prepared for Deputy Asst.
Admin. Drinking Water, March 6. Cr1. Stand. D1v., U.S. EPA, Washington, DC.
Coppola, A., S. D1Blas1, A. Scorsone and G. L1car1. 1963. Thromboelasto-
graphlc changes 1n subacute poisoning with paradlchlorobenzene. Folia
Medlca. (Naples). 4b: 1104-1109.
1837A 14-14 03/29/84
-------
Cotter, L.H. 1953. Case reports: Paradlchlorobenzene poisoning from
Insecticides. N.Y. State J. Med. 53: 1690-1692.
Courtney, K.D. 1979. Hexachlorobenzene (HCB): A review. Environ. Res.
20(2): 225-266.
Courtney, K.D. and E. Andrews. 1979. Mobilization of hexachlorobenzene
(HCB) during gestation. Toxlcol. Lett. 3(6): 357-363.
Courtney, K.D., M.F. Copeland and A. Robblns. 1976. The effects of penta-
chloronltrobenzene, hexachlorobenzene and related compounds on fetal
development. Toxlcol. Appl. Pharmacol. 35: 239-256.
Courtney, K.D., J.E. Andrews and M.T. Ebron. 1977. Teratology study of
pentachlorobenzene 1n mice: No teratogenlc effect at 50 or 100 mg/kg/day
from day 6 to day 15 of gestation. Health Effects Research Lab., Research
Triangle Park, NC. EPA 600-J-77-123. NTIS PB 284 762.
Courtney, K.D., J.F. Andrews and D.J. Svendsgaard. 1979. Hexachlorobenzene
(HCB) deposition 1n maternal and fetal tissues of rat and mouse. I. Chemi-
cal qualification of HCB 1n tissues. Environ. Res. 19(1): 1-13.
Cowen W.F. and R.K. Baynes. 1980. Estimated application of gas chromato-
graphlc headspace analysis to priority pollutants. J. Environ. Sc1. Health.
A15(5): 413-427.
1837A 14-15 03/29/84
-------
Cox, C.B. 1972. Regression model and life tables. J. Roy. Stat. Soc.
B34: 187-220.
Cragg, S.T., G.F. Wolfe and C.C. Smith. 1978. Tox1c1ty of 1,2,4-trlchloro-
benzene 1n Rhesus monkeys: Comparison of two in vivo methods for estimating
P-450 activity. Toxlcol. Appl. Pharmacol. 45(1): 340-341. (Abstr.)
Crlpps, 0., H.A. Peters and A. Gocmen. 1981. PorphyMa turdca (hexa-
chlorobenzene Intoxication) twenty years later. Br. J. Dermatol. 105(519):
15.
Crump, K.S. and W.W. Watson. 1979. GLOBAL79: A Fortran program to extrap-
olate dlchotomous animal cardnogenlcHy data to low doses. Natl. Inst.
Environ. Health Sc1. Contract No. l-ES-2123.
Curley, A., V.W. Burse, R.W. Jennings and E.C. Vlllanueva. 1973. Chlori-
nated hydrocarbon pesticides and related compounds 1n adipose tissue from
people 1n Japan. Nature. 242: 338-340.
Currier, M.F., C.D. McCllmans and G. Barna-Lloyd. 1980. Hexachlorobenzene
blood levels and the health status of men employed 1n the manufacture of
chlorinated solvents. J. Toxlcol. Environ. Health. 6(2): 367-377.
Curtis, M.W. and C.H. Ward. 1981. Aquatic toxiclty of forty Industrial
chemicals: Testing 1n support of hazardous substances spill prevention regu-
lation. J. Hydrol. (Amsterdam). 51(1-4): 359-367.
1837A 14-16 03/29/84
-------
Curtis, M.W., T.L. Copeland and C.H. Ward. 1979. Acute toxlclty of 12
Industrial chemicals to freshwater and saltwater organisms. Water Res.
13(2): 137-142.
Dallch, G.M., R.E. Larson and W.H. G1nger1ch. 1982. Acute and chronic
toxldty studies with monochlorobenzene 1n rainbow trout. Aquatic Toxlcol.
2: 127-142.
Davis, E.M., H.E. Murray, J.G. L1ehr and E.I. Powers. 1981. Basic mlcrob-
1al degradation rates and chemical by-products of selected organic com-
pounds. Water Res. 15(9): 1125-1127.
Davis, H.C. and H. Hindu. 1969. Effects of pesticides on embryonic
development of clams and oysters and on survival and growth of the larvae.
U.S. F1sh W1ldl. Serv. F1sh Bull. 67(2): 393-403.
Dawson, G.W., A.L. Jennings, D. Drozdowskl and E. Rider. 1977. The acute
toxlclty of 47 Industrial chemicals to fresh and saltwater fishes. J.
Hazard. Mater. 1(4): 303-318.
Debets, F.M.H., W.J.H.M.B. Hamers and J.J.T.W.A. Strlk. 1980a. Metabolism
as a prerequisite for the porphyrlnogenlc action of polyhalogenated aro-
matlcs, with special reference to hexachlorobenzene and polybromlnated
blphenyls (Flremaster BP-6). Int. J. Blochem. 12(5-6): 1019-1025.
1837A 14-17 03/29/84
-------
Debets F.M.H., J.J.T.W.A. StMk and K. Ol1e. 1980b. Effects of penta-
chlorophenol on rat liver changes Induced by hexachlorobenzene, with special
reference to porphyrla, and alterations 1n mixed function oxygenases. Toxi-
cology. 15(3): 181-195.
De CeaurMz, J.C., J.C. M1c1ll1no, P. Bonnet and J.P. Guenler. 1981. Sen-
sory Irritation caused by various Industrial airborne chemicals. Toxlcol.
Lett. (AMST). 9(2): 137-144.
DeLeon, I.R., M.A. Maberry, E.B. Overton, et al. 1980. Rapid gas chromato-
graphlc method for the determination of volatile and semlvolatlle organo-
chlorlne compounds 1n soil and chemical waste disposal site samples. J.
Chromatogr. Sc1. 18: 85-88.
DeMattels, F. 1967. Disturbances of liver porphyrla metabolism caused by
drugs. Pharmacol. Rev. 19: 523-557.
DUley, J.V. 1977. Toxic evaluation of Inhaled chlorobenzene (monochloro-
benzene). Prepared by Stanford Res. Inst. under Contract 210-76-0126.
NIOSH, DHEW, Cincinnati, OH. NTIS PB 276 623.
D1ll1ng, W.L., C.J. Bredeweg and N.B. Tefertlller. 1976. Simulated atmos-
pheric photodecomposltlon rates of methylene chloride, 1,1,l-tr1chloro-
ethane, trlchloroethylene, tetrachloroethylene, and other compounds.
Environ. Sc1. Technol. 10(4): 351-356.
1837A 14-18 03/29/84
-------
Oomenjoz, R. 1946. Zur B1olog1schen Wlrkung E1n1ger DOT-Der1vate. Arch.
Int. Pharmacodyn. 73: 128-146.
Dougherty, R.C., M.J. WhHaker, S-Y. Tang, R. Bottcher, M. Keller and D.W.
Kuehl. 1981. Sperm density and toxic substances: A potential key to
environmental health hazards. Environ. Health Chem., Chem. Environ. Agents
Potential Hum. Hazards (Symp.), J.D. McKlnney, Ed. p. 263-278.
Dow Chemical Company. 1979-1980. Material safety data sheets - mono-
chlorobenzene, o-d1chlorobenzene, p-d1chlorobenzene, 1,2,4-tr1chlorobenzene,
1,2,4,5-tetrachlorobenzene. Midland, MI.
Dow Chemical Company. 1978a. Comments on the first ten designations of the
TSCA Interagency Testing Committee. OTS-040002. U.S. EPA, Washington, DC.
(Cited 1n: U.S. EPA, 1980a)
Dow Chemical Company. 1978b. TSCA sec. 8(d) submission 8DHQ-0978-0299.
Dynamic acute toxldty of selected phenol and benzene compounds to rainbow
trout. Salmo galrdnerla [sic] Richardson, 1974. OTS, U.S. EPA, Washington,
DC.
Downing, J.G. 1939. Dermatitis from orthodlchlorobenzene. J. Am. Med.
Assoc. 112(15): 1457.
Dowty, B.J., J.L. Laseter and J. Storer. 1976. The transplacental migra-
tion and accumulation 1n blood of volatile organic constituents. Pedlat.
Res. 10: 696-701.
1837A 14-19 03/29/84
-------
Drlpps, R.D., J.E. Eckenhoff and L.O. Vandem. 1977. Introduction to
Anesthesia: The Principles of Safe Practice, 5th ed. W.B. Saunders Company,
Philadelphia, PA. p. 121-123.
Easley, D.M., R.O. Kleopfer and A.M. Carasea. 1981. Gas chromatographlc-
mass spectrometrlc determination of volatile organic compounds 1n fish. J.
Assoc. Off. Anal. Chem. 64(3): 653-656.
Eastman Kodak Company. 1978. Tox1c1ty and Health Hazard Summary on Mono-
chlorobenzene. OPTS, U.S. EPA, Washington, DC. TSCA Section 8(d) submis-
sion 8DHQ-0978-0039. (Cited 1n: U.S. EPA, 1980a)
Elceman, G.A., R.E. Clement and F.W. Karasek. 1979. Analysis of fly ash
from municipal Incinerators for trace organic compounds. Anal. Chem.
51(14): 2343-2350.
Elceman, G.A., R.E. Clement and F.W. Karasek. 1981. Variations 1n concen-
trations of organic compounds Including polychlorlnated d1benzo-p-d1ox1ns
and polynuclear aromatic hydrocarbons 1n fly ash from a municipal Incinera-
tor. Anal. Chem. 53(7): 955-959.
Elder, G.H., J.O. Evans and S.A. MatHn. 1976. The effect of the porphyro-
genlc compound, hexachlorobenzene, on the activity of hepatic uroporphyrlno-
gen decarboxylase 1n rat. Cl1n. Sc1. Mol. Med. 51: 71-80.
1837A 14-20 03/29/84
-------
Elder, V.A., B.I. Proctor and R.A. HHes. 1981. Organic compounds found
near dump sites 1n Niagara Falls, New York. Environ. Sc1. Technol. 15(10):
123/-1243.
EUssalde, M.H. and D.E. Clark. 1979. Testosterone metabolism by hexa-
chlorobenzene-lnduced hepatic mlcrosomal enzymes. Am. J. Vet. Res. 40(12):
1762-1766.
Engst, R., R.M. Macholz and M. Kujawa. 1976a. The metabolism of hexa-
chlorobcnzene (HCB) 1n rats. Bull. Environ. Contam. Toxlcol. 16(2):
248-251.
Engst, R., R.M. Macholz, M. Kujawa, H-J. Lewerenz and R. Plass. 19766. The
metabolism of lindane and Its metabolites gamma-2,3,4,5,6-pentachlorocyclo-
hexene, pentachlorobenzene and pentachlorophenol 1n rats and the pathways of
lindane metabolism. J. Environ. Sd. Health Bull. Bll(2): 95-117.
Engst, R., R.M. Macholz and M. Kujawa. 1979. Metabolism of lindane 1n
mlcroblal organisms, warm-blooded animals and humans. 61g. Sanlt. 10:
64-65.
Falco, J.W., L.A. Mulkey, R.R. Swank, Jr., R.E. L1pcse1 and S.M. Brown.
1982. A screening procedure for assessing the transport and degradation of
solid waste constHutents 1n subsurface and surface waters. Environ.
Toxlcol. Chem. 1: 121-134.
1837A 14-21 03/29/84
-------
Farmer, W.J., M.S. Yang, J. Letey and W.F. Spencer. 1980. Hexachloroben-
zene: Its vapor pressure and vapor phase diffusion In soil. Soil Sc1. Soc.
Am. J. 44(4): 676-680.
FASEB {Federation of American Societies for Experimental Biology). 1974.
Biology Data Book, 2nd ed., Vol. Ill, P.L. Altman and O.S. DHtmen, Ed.
Bethesda, MD. Library of Congress No. 72-87738.
Fielding, M. T.M. Gibson and H.A. James. 1981. Levels of trlchloroethy-
lene, tetrachloroethylene and p-d1chlorobenzene 1n groundwaters. Environ.
Technol. Lett. 2(12): 545-550.
Fomenko, V.N. 1965. Determination of the maximum permissible concentration
of tetrachlorobenzene 1n water basins. Hyg. SanH. 30: 8-15.
Frank, S.B. and H.J. Cohen. 1961. Fixed drug eruption due to paradlchloro-
benzene. New York J. Med. 61: 4079.
Frank, R., H.E. Braun, M. Holdrlnet, G.J. Slrons, E.H. Smith and D.W. D1xon.
1979. Organochlorlne Insecticides and Industrial pollutants 1n the milk
supply of southern Ontario, Canada - 1977. J. Food Prot. 42(1): 31-37.
Fre1re1ch, E., E. Gehan, D. Rail, L. Schmidt and E. Skipper. 1966. Quan-
titative comparison of toxldty of antlcancer agents 1n mouse, rat, hamster,
dog, monkey and man. Cancer Chemother. Rep. 50(4): 219-244.
183/A 14-22 03/29/84
-------
Gabor, S. and K. Raucher. 1960. Studlen zur Bestlmmung der zulasslgen ben-
zol und monochlorbenzol Grenzkonzentratlonen. J. Hyg. Ep1dem1ol. M1crob1ol.
Immunol. 4: 223-231.
Gadrat, J., J. Monnier, A. R1bet and R. Bourse. 1962. Acute hemolytlc
anemia 1n a female worker of a dyeing and dry-cleaning shop exposed to Inha-
lation of chlorobenzenes. Arch. Maladies Prof. Med. Travail Securlte
Sodale. 23(10/11): 710-714. (Fre.)
Gaffney, P.E. 1976. Carpet and rug Industry case study II: Biological
effects. J. Water Pollut. Contr. Fed. 48(12): 2731-2737.
Garrison, A.M. and O.W. Hill. 1972. Organic pollutants from mill persist
1n downstream waters. Am. Dyestuff Rep. p. 21-25.
Gelke, F. and C.D. Parasher. 1976. Effect of hexachlorobenzene (HCB) on
growlh of Tetrahymena pyrlformls. Bull. Environ. Contam. Toxlcol. 16(3):
347-354.
Gibson, A.L. 1957. Tests of bark-penetrating Insecticides to control the
Douglas-fir beetle. Econ. Entomol. 50: 266-268.
G1ger, W., M. Relnhard, C. Schaffner and F. Zureher. 197b. Analyses of
organic constituents 1n water by high-resolution gas chromatography 1n com-
bination with specific detection and computer-assisted mass spectrometry.
In: Identification and analysis of organic pollutants 1n water, L.H. Keith,
ed. Ann Arbor Science Publishers, Inc., Ann Arbor, MI. p. 433-452.
1837A 14-23 03/29/84
-------
Gllbertson, M. and G.A. Fox. 1977. Pollutant-associated embryonic mortal-
ity of great lakes herring gulls. Environ. Pollut. 12: 211-216.
Gllbertson, M. and L.M. Reynolds. 1972. Hexachlorobenzene (HCB) In the
eggs of common terns 1n Hamilton Harbour, Ontario. Bull. Environ. Contam.
Toxlcol. 7(6): 371-373.
Gllman, A.P., G.A. Fox, D.B. Peakall, S.M. Teeple, T.R. Carroll and G.T.
Haymes. 1977. Reproductive parameters and egg contaminant levels of Great
Lakes herring gulls. J. W1ldl. Manage. 41(3): 458-468.
G1nger1ch, W.H. and G.M. Oallch. 1978. An evaluation of liver toxldty 1n
rainbow trout following treatment with monochlorobenzcne. Proc. West.
Pharmacol. Soc. 21: 475-480.
Glrard, R. 1969. Serious blood disorders and exposure to chlorine deriva-
tives of benzene (a report of seven cases). Med. Lyon. 50: 771.
Glrard, R., F. lolot, P. Martin and J. Bourret. 1969. Serious blood dis-
orders and exposure to chlorine derivatives of benzene (A report of 7
cases). J. Med. Lyon. 50(1164): 771-773. (Fre.)
Goerz, G.t W. Vlzethum, K. Bolsen, Th. Krleg and R. llssner. 1978. Hexa-
chlorobenzene (HBC)-lnduced porphyrla 1n rats. Effect of HCB-metabol1tes on
heme biosynthesis. Arch. Oermatol. Res. 263(2): 189-196. (Ger.)
183/A !4-?4 03/29/84
-------
Goldstein, J.A., M. FMesen, T.M. Scottl, P. Hlckman, J.R. Mass and H.
Bergman. 1978. Assessment of the contribution of chlorinated d1benzo-p-
dioxins and dlbenzofurans to hexachlorobenzene-lnduced toxicity, porphyrla,
changes 1n mixed function oxygenases, and hlstopathologlcal changes.
Toxlcol. Appl. Pharmacol. 46(3): 633-649.
Goldstein, J.A., P. L1nko, J.N. Hucklns and D.L. Stalling. 1982. Struc-
ture-activity relationships of chlorinated benzenes as Inducers of different
forms of cylochrome P 450 1n rat liver. Chem. B1ol. Interact. 41(2):
131-139.
Goto, M., M. Hattorl, T. Mlyagawa and M. Enomoto. 1972. Beltrage zur
okologlschen chemle. II. Hepatoma-blldung 1n mausen nach verabrelchung von
HCII-1someren 1n hohen dosen. Chemosphere. 6: 279-282. (Ger.)
Graedel, I.E. 1978. Chemical Compounds in the Atmosphere. Academic Press.
p. 334-337.
Graef, V., S.W. Golf and G. Goerz. 1979. Effect of hexachlorobenzene on
enzymes of steroid metabolism 1n rat liver. Arch. Toxlcol. 43(2): 115-120.
Gralla, E.J., R.W. Flelschman, Y.K. Luthra, et al. 1977. Toxic effects of
hexachlorobenzene after dally administration to beagle dogs for one year.
Toxlcol. Appl. Pharmacol. 40(2): 227-239.
Granick, S. 1965. Hepatic porphyrla and drug-Induced or chemical por-
phyrla. Ann. N.Y. Acad. Scl. 123: 188-197.
1837A 14-25 03/29/84
-------
Grant, D.L., F. Iverson, G.U. Hatlna and O.C. Vllleneuve. 1974. Effects of
hexachlorobenzene on liver porphyrln levels and mlcrosomal enzymes In rats.
Environ. Physlol. Blochem. 4: 159.
Grant, D.L., W.E.J. Phillips and G.V. Hatlna. 1977. Effect of hexachloro-
benzene on reproduction 1n the rat. Arch. Environ. Contam. Toxlcol. 5(2):
207-216.
Grasselll, J.G., Ed. 1973. Atlas of Spectral Data and Physical Constants
for Organic Compounds. CRC Press, Cleveland, OH.
Griffin, R.A. and S.F.J. Chou. 1981. Movement of PCB's and other per-
sistent compounds through soil. Water Sc1. Technol. (England). 13(4-5):
1153-1163.
Grosch, D.S. 1973. Reproduction tests: The toxldty for Artemla of deriva-
tives from non-persistent pesticides. B1ol. Bull. 145: 340-351.
Grosch, D.S. and A.C. Hoffman. 1973. The vulnerability of specific cells
1n the oogenetlc sequence of Bracon hebetor say to some degradation products
of carbamate pesticides. Environ. Entomol. 2(6): 1029-1032.
Grzenda, A.R., G.J. Lauer and H.P. Nicholson. 1964. Water pollution by
Insecticides 1n an agricultural river basin. II. The zooplankton, bottom
fauna, and fish. Llmnol. Oceanog. 9: 318-323.
1837A 14-26 03/29/84
-------
Guerzonl, M.E., L. Del Cupolo and I. Ponti. 1976. Mutagenlc activity of
pesticides. (Att1v1ta mutagenlca degll antlporossltarl.) R1v. Sc1. Tech-
nol. Alementl Nutrl. Urn. 6: 161-165.
Gurfeln, L.N. and Z.K. Pavlova. 1960. Maximum allowable concentration of
chlorinated benzene 1n water supplies. Sanlt. Okhrana Vod. Zagryaznenlya
Prom. Stochrayml Vodaml. (4): 117-127. (Cited In: CA 56: 70601)
Hallett, O.J., R.J. Norstrom, F.I. Onuska and M.E. Comba. 1982. Incidence
of chlorinated benzenes and chlorinated ethylenes 1n Lake Ontario Herring
Gulls. Chemosphere. 11(3): 277-285.
Hallowell, M. 1959. Acute haemolytlc anaemia following the Ingestlon of
para-dlchlorobenzene. Arch. D1s. Child. 34: 74-75.
Hansch, C. and A.J. Leo. 1981. Medchem Project. Issue No. 19. Pamona
College, CA.
Hansen, L.G., R.H. Teske, S.M. Sundlof and J. Simon. 1979. Hexachloroben-
zene and feline reproduction: Effects of ground pork contaminated by dietary
exposure or spiked with purified hexachlorobenzene. Vet. Hum. Toxlcol.
21(4): 248-253.
Harden, R.A. and A.M. Baetjer. 1978. Aplastlc anemia following exposure to
para-dlchlorobenzene and naphthalene. J. Occup. Med. 20(12): 820-822.
1837A 14-27 03/29/84
-------
HarcMe, D.W.F. 1964. Chlorinated benzenes. K1rk Othmer Encyclopedia of
Chemical Technology, 2nd ed., Vol. 5. John Wiley and Sons, Inc., New York.
Markov, R., R. Katz, J. BozzelH and B. Kebbekus. 1981. Toxic and carcino-
genic air pollutants 1n New Jersey - volatile organic substances. Proc.
Int. Tech. Conf. Toxic A1r Contain, p. 104-119.
Haseltlne, S.O., 6.H. Heinz, W.L. Relchel and J.F. Moore. 1981. Organo-
chloMne and metal residues 1n eggs of waterfowl nesting on Islands 1n Lake
Michigan off Door County, Wisconsin, 1977-78. Pest. Monlt. J. 15(2): 90-97.
Hawkins, D.R., L.F. Chasseaud, R.N. Woodhouse and D.6. Cresswell. 1980.
The distribution, excretion and blotransformatlon of p-d1chloro(l4C)ben-
zene 1n rats after repeated Inhalation, oral and subcutaneous doses. Xeno-
blotlca. 10(2): 81-95.
Hawley, G.G. 1977. Condensed Chemical Dictionary, 9th ed. Van Nostrand
Relnhold Company, NY.
Headley, D.B., R.W. Lambrecht, E. Erturk, H.A. Peters, C.R. Morris and G.T.
Bryan. 1981. Neuropathology and tissue levels of hexachlorobenzene (HCB)
fed to rats, mice and hamsters. Fed. Proc. Fed. Am. Soc. Exp. Blol.
40(3): 699. (Abstr.)
Heltmuller, P.T., T.A. Holllster and P.R. Parrlsh. 1981. Acute toxldty of
54 Industrial chemicals to sheepshead minnows (Cyprlnodon varlegatus).
Bull. Environ. Contam. Toxlcol. 27(5): 596-604.
1837A 14-28 03/29/84
-------
Hiatt, M.H. 1981. Analysis of fish and sediment for volatile priority pol-
lutants. Anal. Chem. 53(9): 1541-1543.
H1tes, R.A. 1973. Analysis of trace organic compounds 1n New England
rivers. J. Chromatogr. Sc1. 11: 570-574.
*
Hofvander, Y., U. Hagman, C.-E. Under, R. Vaz and S.A. Slorach. 1981. WHO
collaborative breast feeding study. I. OrganochloMne contaminants 1n
Individual samples of Swedish human milk, 1978-1979. Acta. Paedlatr. Scand.
70(1): 3-8.
Holllngsworth, R.L., V.K. Rowe, F. Oyen, H.R. Hoyle and H.C. Spencer. 1956.
Toxlclty of paradlchlorobenzenes. Determinations of experimental animals
and human subjects. Am. Med. Assoc. Arch. Ind. Health. 14(1956): 138-147.
Holllngsworth, R.L., V.K. Rowe, F. Oyen, T.R. Torkelson and I.H. Adams.
1958. Toxldty of o-d1chlorobenzene. Studies on animals and Industrial
experience. Am. Med. Assoc. Arch. Ind. Health. 17(1): 180-187.
Horvath, A.L. 1982. Halogenated Hydrocarbons. Solubility - H1sc1b1l1ty
with Water. Marcel Dekker, Inc., NY. p. 530.
Howe, R.B. and K.S. Crump. 1982. GLOBAL82: A computer program to extrapo-
late quantal animal toxldty data to low doses. OSHA Contract No. 41
USC252C3.
1837A 14-29 03/29/84
-------
IARC (International Agency for Research on Cancer). 1979. IARC monographs
on the evaluation of the carcinogenic risk of chemical to humans. Hexa-
chlorobenzene. IARC, Lyon, France. 20: 155-178.
latropoulos, M.J., A. Milling, W.F. MQller, et al. 1975. Absorption,
transport and organotroplsm of dlchloroblphenyl (DCB), dleldrln, and hexa-
chlorobenzene (HCB) 1n rats. Environ. Res. 10(3): 384-389.
latropoulos, M.J., W. Hobson, V. Knauf and H.P. Adams. 1976. Morphological
effects of hexachlorobenzene toxlclty 1n female Rhesus monkeys. Toxlcol.
Appl. Pharmacol. 37: 433-444.
latropoulos, M.J., J. Bailey, H.P. Adams, F. Coulston and W. Hobson. 1978.
Response of nursing Infant Rhesus to Clophen A-30 or hexachlorobenzene given
to their lactatlng mothers. Environ. Res. 16(1-3): 38-47.
ICRP (International Commission on Radiological Protection). 1975. No. 23
Report of the Task Group on Reference Man. Pergamon Press, NY. p. 346, 360.
ICRP (International Commission on Radiological Protection. 1977. Recom-
mendation of the ICRP. Publ. No. 26, January 17. Pergamon Press, Oxford,
England.
IngebMgtsen, K., J.U. Skaare, I. Nafstad and M. Fdrde. 1981. Studies
on the excretion and metabolites of hexachlorobenzene 1n the rat. Xeno-
blotlca. 11(11): 795-800.
1837A 14-30 03/29/84
-------
Ir1e, D, T. Sasaki and R. Ito. 1973. Acute tox1c1ty, Inhalation toxldty
and skin Irritation of cyclododecane, trlchclododecane, naphthaline and
p-d1chlorobenzene (parazol). Toho Igakkal Zasshl, Toho Univ., Toho, Japan.
20(5-6): 772-775.
Irish, O.D. 1963. Halogenated hydrocarbons: II. Cyclic. ln_: Industrial
Hygiene and Toxicology, 2nd rev. ed., Vol. II, F.A. Patty, Ed. Intersdence
Publishers, New York. p. 1333-1340.
Isensee, A.R., E.R. Holden, E.A. Woolson and G.E. Jones. 1976. Soil per-
sistence and aquatic bloaccumulatlon potential of hexachlorobenzene (HCB).
J. AgMc. Food Chem. 24(6): 1210-1214.
Ito, N., M. Tatematsn, K. Nakan1sh1, et al. 1980. The effects of various
chemicals on the development of hyperplastlc liver nodules 1n hepatectomlzed
rats treated with N-n1trosod1ethyl-am1ne or N-2-fluorenylacetamlde. Gann.
71: 832-842.
Jacobs, A., M. Blangettl and E. Hellmund. 1974a. Accumulation of noxious
chlorinated substances from Rhine River water 1n the fatty tissue of rats.
Vom Wasser. 43: 259-274.
Jacobs, A., M. Blangettl and E. Hellmund. 1974b. Accumulation of organic
compounds, Identified as harmful substances 1n Rhine water, 1n the fatty
tissue of rats. Dernforschungszentrum Karlsruhe. KRK 2969 UF. p. 1.
(Abstr.) (Cited 1n: U.S. EPA, 1980b)
1837A 14-31 03/29/84
-------
Jacobs, A., E. Hellmund and S.H. Eberle. 1977. Accumulation of trace water
pollutants in living organisms: Time and dose dependence of the accu-
mulation of hexachlorobenzene and tetrachlorobenzene derivatives In rats.
VomWasser. 48: 255-272. (Ger.)
Jergll, B., C. Schelln and A. Tunek. 1982. Covalent binding of metabolic-
ally activated hydrocarbons to specific mlcrosomal proteins. Adv. Exp. Med.
Biol. 136A (Biol. React. Intermed.-2, Chem. Mech. Biol. Eff., Pt. A),
341-348.
Johnson, R.O. and D.D. Manske. 1976. Pesticide residues in total diet
samples (IX). Pest. Monit. J. 9(4): 157-167.
Jondorf, W.R., D.V. Parke and R.T. Williams. 1955. Studies 1n detoxica-
tlon. 66. Ihe metabolism of halogenobenzenes, 1,2,3-, 1,2,4- and 1,3,5-
trlchlorobenzenes. Blochem. J. 61: 512-521.
Jondorf, W.R., O.V. Parke and R.T. Williams. 1958. Studies in detoxlca-
tion. 76. The metabolism of halogenobenzenes 1,2,3,4-, 1,2,3,5- and
1,2,4,5-tetrachlorobenzenes. Blochem. J. 69: 181-189.
Jungclaus, G.A. V. Lopen-Avila and R.A. H1tes. 1978. Organic compounds in
an industrial waste water: A case study of their environmental Impact.
Environ. Sci. Technol. 12(1): 88-96.
1837A 14-32 03/29/84
-------
Kaiser, I.E., W.L. Relchel, L.N. Locke, et al. 1980. Organochlorlne
pesticide, PCB, and PBB residues and necropsy data for bald eagles from 29
states — 1975-1977. Pest. MonH. J. 13(4): 145-149.
Kanno S. and K. Nojlma. 1979. Studies on photochemistry of aromatic hydro-
carbons. V. Photochemical reaction of chlorobenzene with nitrogen oxides 1n
air. Chemosphere. 8(4): 225-232.
Kao, C.I. and N. Poffenberger. 1979. Chlorinated benzenes. In.: KlrkOthmer
Encyclopedia of Chemical Technology, 3rd ed., Vol. 5. John Wiley and Sons,
New York. p. 797-808.
Kawasaki, M. 1980. Experiences with the test scheme under the chemical
control law of Japan: An approach to structure-activity correlations.
Ecotox. Environ. Safety. 4: 444-454.
Kenaga, E.E. and C.A.I. Goring. 1980. Relationship between water solubil-
ity, soil sorptlon, octanol-water partitioning, and concentration of chemi-
cals 1n biota, in: Aquatic Toxicology, J.G. Eaton, P.R. ParMsh, and A.C.
Hendrlcks, Ed. Am. Soc. Test. Mater, p. 78-115.
Kesklnova, D.V. 1968. The effect of dlmethylcyclodlazomethane 1n chloro-
benzene solution on mutagenesls 1n Actlnomyces antlblotlcus 400. Genetlka.
4(8): 121-125. (Cited 1n: U.S. EPA, 1980a)
1837A 14-33 03/29/84
-------
Khanln, A.G. 1977. Pathological changes 1n the general nervous system and
Internal organs of experimental animals after chronic continuous Inhalation
of toxic substances. CA 74: 97-106. (Cited 1n: U.S. EPA, 1980a)
Khera, K.S. 1974. Teratogenldty and dominant lethal studies on hexa-
chlorobenzene 1n rats. Food Cosmet. Toxlcol. 12: 471-477.
Khera, K.S. and D.C. Vllleneuve. 1975. Teratogenldty studies on halo-
genated benzenes (pentachloro-, pentachloronltro-, and hexabromo-) 1n rats.
Toxicology. 5(1): 117-122.
Klmura, R., T. Hayashl, M. Sato, T. Almoto and T. Murata. 1979. Identifi-
cation of sulfur-containing metabolites of p-d1chlorobenzene and their dis-
position 1n rats. J. Pharm. Dyn. 2(4): 237-244.
Klraly, J., I. Szentesl, M. Ruzlcska and A. Czelze. 1979. Chromosome stud-
ies In workers producing organophosphorus Insecticides. Arch. Environ.
Contam. Toxlcol. 8(3): 309-319.
KHchln, K.T., R.E. Under, T.M. Scottl, D. Walsh, A.D. Curley and 0.
Svensgaard. 1982. Offspring mortality and maternal lung pathology 1n
female rats fed hexachlorobenzene. Toxicology. 23(1): 33-39.
Klaassen, C.D. 1980. Absorption, distribution, and excretion of toxicants.
I_n: Casarett and Douells's Toxicology. The Basic Science of Poisons, 2nd
ed., J. Oouell, C.D. Klaassen and M.O. Amdur, Ed. Macmlllan Publishing Co.,
New York. p. 28-51.
1837A 14-34 03/29/84
-------
Kluwe, W.M., J.B. Hook and J. Bernstein. 1982. Synerg1st1c tox1c1ty of
carbon tetrachloMde and several aromatic organohallde compounds. Toxi-
cology (Ireland). 23(4): 321-336.
Knauf, V. and W. Hobson. 1979. Hexachlorobenzcne ingestlon by female
Rhesus monkeys: Tissue distribution and clinical symptomatology. Bull.
Environ. Contam. Toxlcol. 21(1-2): 243-248.
Kodba, R.J., B.K. Leong and R.E. Hefner, Jr. 1981. Subchronlc toxldty
study of 1,2,4-tr1chlorobenzene 1n the rat, rabbit and beagle dog. Drug
Chem. Toxicol. 4(3): 229-249.
Kodr1c-Sm1t, M., Z. Sm1t and K. OHe. 1980. Organochlorlne contaminants 1n
human milk from Slavonla Province, Yugoslavia, 1978. Pest. Monlt. J.
14(1): 1-2.
KohH, J., D. Jones and S. Safe. 1976a. The metabolism of higher chlori-
nated benzene Isomers. Can. J. Blochem. 54(3): 203-208.
Kohll, J., I. Welsgerber and W. Klein. 1976b. Balance of conversion of
[14C] Undane 1n lettuce 1n hydroponlc culture. Pest. Blochem. Physlol.
&: 91-97.
Kohll, J., I. Welsgerber, W. Klein and F. Korte. 1976c. Contributions to
ecological chemistry. CVII. Fate of Hndane-14C 1n lettuce, endives and
soil under outdoor conditions. J. Environ. Sc1. Health. Bll(l): 23-32.
1837A 14-35 03/29/84
-------
Konemann, H. and K. van Loeuwen. 1980. Tox1cok1net1cs 1n fish: Accumula-
tion and elimination of six chlorobenzenes by gupples. Chemosphere. 9(1):
3-19.
Konemann, H., R. Zella, F. Busser and W.E.J. Hammers. 1979. Determination
of log P values of chloro-substHuted benzenes, toluenes and anilines
by high-performance liquid chromatography on ODS-s1l1ca. J. Chromatography.
178: 559-565.
Koss, G. and W. Koransky. 1975. Studies on the toxicology of hexachloro-
benzene. I. Pharmacok1net1cs. Arch. Toxlcol. 34: 203-212.
Koss, G. and W. Koransky. 1977. Pentachlorophenol 1n different species of
vertebrates after administration of hexachlorobenzene and pentachloroben-
zene. J.TK Pentachlorophenol, K.R. Rao, Ed. Plenum Press, NY. p. 131.
Koss, G. and D. Manz. 1976. Residues of hexachlorbenzene In wild mammals
of Germany. Bull. Environ. Contam. Toxlcol. 15(2): 189-191.
Koss, G., W. Koransky and K. Stelnbach. 1976. Studies on the toxicology of
hexachlorobenzene. II. Identification and determination of metabolites.
Arch. Toxlcol. 35: 107-114.
Koss, G., J.J.T.W.A. Strlk and C.A. Kan. 1978a. Metabolites of hexachloro-
benzene 1n the excreta of different animal species. Int. Consv. Series.
Exerpta Medlca. 440: 211-212.
1837A 14-36 03/29/84
-------
Koss, G., S. Seubert, A. Seubert, W. Koransky and H. Ippen. 1978b. Studies
on the toxicology of hexachlorobenzene. III. Observations 1n a long-term
experiment. Arch. Toxlcol. 40(4): 285-294.
Koss, G., S. Seubert, A. Seubert, W. Koransky, P. Kraus and H. Ippenet.
1980a. Conversion products of hexachlorobenzene and their role 1n the
disturbance of the porphyrln pathway 1n rats. Int. J. Blochem. 12(5-6):
1003-1006.
Koss, G., S. Seubert, A. Seubert, M. Herbert, W. Koransky and H. Ippen.
1980b. Hexachlorobenzene and 2,4,5,2',4',5'-hexachlorob1phenyl -- A com-
parison of their distribution, blotransformatlon and porphyrlnogenlc action
1n female rats. Oev. Toxlcol. Environ. Sc1., ISS. Mech. Toxic. Hazard Eval.
8: 517-520.
Koss, G., S. Seubert, A. Seubert, J. Seldel, W. Koransky and H. Ippen.
1983. Studies on the toxicology of hexachlorobenzene. V. Different phases
of porphyMa during and after treatment. Arch. Toxlcol. 52: 13-22.
Koszo, F., C. S1klos1 and N. Simon. 1978. Hexachlorobenzene porphyMa and
hexachlorobenzene catabollsm 1n rats. Blochem. Blophys. Res. Commun.
80(4): 781-788.
Kovar, J. and D. Krewskl. 1981. RISK81: A computer program for low-dose
extrapolation of quantal response toxldty data. Dept. Health Welfare,
Canada.
1837A 14-37 03/29/84
-------
Krayblll, H. 1983. Personal communication to MuMal M. Lippman, ERNACO,
Inc., Silver Springs, MO.
Krost, K.J., E.D. Pell1zzar1, S.G. Walburn and S.A. Hubbard. 1982. Col-
lection and analysis of hazardous organic emissions. Anal. Chem. 54(4):
810-817.
Kuehl, D.W., E.N. Leonard, K.J. Welch and G.D. Velth. 1980. Identification
of hazardous organic chemicals 1n fish from the Ashtabula River, Ohio, and
Wabash River, Indiana. J. Assoc. Off. Anal. Chem. 63(6): 1238-1244.
Ku1 per-Goodman, T., O.L. Grant, C.A. Moodle, G.O. Korsrud and I.C. Munro.
1977. Subacute toxldty of hexachlorobenzene 1n the rat. Toxlcol. Appl.
Pharmacol. 40(3): 529-549.
Kw1atkowsk1, G.T., G.L. Brode and A.M. Bedwln. 1976. ChloroaromatU ether
amines. J. Poly. Sd. 14: 2649-2657.
Lambrecht, R.W. 1983. Personal communication to MuMal M. Lippman, ERNACO,
Inc., Silver Springs, MO.
Lambrecht, R.W. 1984. Personal communication to Murlal M. Lippman, ERNACO,
Inc., Silver Springs, MD.
1837A 14-38 03/29/84
-------
Lambrecht, R.W., B.A. Darcey, E. Erturk, et al. 1981. Tissue levels and
fate of hexachlorobenzene (HCB) disappearance In fat and liver of rats, mice
and hamsters after oral administration. Proc. Am. Assoc. Cancer Res.
22: 127 (Abstr.)
Lambrecht, R.W., E. Erturk, E. Grunden, et al. 1982a. Hepatotoxldty and
tumoMgenlcHy of hexachlorobenzene (HCB) 1n Syrian golden hamsters (H)
after subchronlc administration. Fed. Proc. 41:(3): 329. (Abstr.)
Lambrecht, R.W., E. Erturk, E. Grunden, et al. 1982b. Renal toxldty and
tumorlgenlclty of hexachlorobenzene (HCB) 1n rats. Proc. Am. Assoc. Cancer
Res. 23: 54. (Abstr.)
Lambrecht, R.W., E. Ertriik, E.E. Grunden, H.A. Peters, C.R. Morris and G.T.
Bryan. 1983a. Renal tumors 1n rats (R) chronically exposed to hexachloro-
benzene (HCB). Proc. Am. Assoc. Cancer Res. 24: 59. (Abstr.)
Lambrecht, R.W., E. Ertruk, E.E. GMnden, H.A. Peters, C.R. Morris and G.T.
Bryan. 1983b. Hepatocardnogen1c1ty of chronically administered hexa-
chlorobenzene 1n rats. Fed. Proc. 42(4): 786. (Abstr.)
Lamparskl, L.L., M.L. Langhorst, T.J. Nestrlck and S. Cutle. 1980. Gas-
I1qu1d chromatographlc determination of chlorinated benzenes and phenols 1n
selected biological matrices. J. Assoc. Off. Anal. Chem. 63(1): 27-32.
1837A 14-39 03/29/84
-------
Langhorst, M.L. and T.J. NestMck. 1979. Determination of chlorobenzenes
1n air and biological samples by gas chromatography with photolonlzatlon
detection. Anal. Chem. 51(12): 2018-2025.
Laseter, J.L., C.K. Bartell, A.L. Laska, et al. 1976. An ecological study
of hexachlorobenzene (HCB). OTS, U.S. EPA, Washington, DC. EPA
560/6-76-009. NTIS PB 252 651.
Laska, A.L., C.K. Bartell, D.B. Condle, J.W. Brown, R.L. Evans and J.L.
Laseter. 1978. Acute and chronic effects of hexachlorobenzene and hexa-
chlorobutadiene 1n Red Swamp crayfish (Procambarus clarkl) and selected fish
species. Toxlcol. Appl. Pharmacol. 43: 1-11.
Lawlor, T., S.R. Haworth and P. Voytek. 1979. Evaluation of the genetic
activity of nine chlorinated phenols, seven chlorinated benzenes, and three
chlorinated hexanes. Environ. Mutagen. 1: 143. (Abstr.)
LeBlanc, G.A. 1980. Acute toxldty of priority pollutants to water flea
(Daphnla magna). Bull. Environ. Contam. Toxlcol. 24: 684-691.
Lee, R.F. and C. Ryan. 1979. M1crob1al degradation of organochlorlne com-
pounds 1n estuarlne water and sediments. NTIS PB 298254.
Leo, A., C. Hansch and D. Elklns. 1971. Partition coefficients and their
uses. Chem. Rev. 71(6): 525-616.
1837A 14-40 03/29/84
-------
Leonl, V. and S.U. D'Arca. 1976. Experimental data and critical review of
the occurrence of hexachlorobenzene 1n the Italian environment. Sd. Total
Environ. 5(3): 253-272.
Levlnson, Z.H. 1955. Chemicals affecting the prelmaglnal stages of the
housefly. V. Vapour toxldty of the dlchlorobenzenes to housefly pupae.
R1v. ParassHol. 16(4): 253-256.
Lewis, R.6. and K.E. MacLeod. 1982. Portable sampler for pesticides and
semlvolatlle Industrial organic chemicals 1n air. Anal. Chem. 54: 310-315.
L1, R.T., J.L. SplgarelH and J.E. Going. 1976. Sampling and analysis of
selected toxic substances. Task lA-Hexachlorobenzene. OTS, U.S. EPA, Wash-
ington, DC. EPA 560/676/001.
Llnder, R., T. Scottl, J. Goldstein, K. McElroy and 0. Walsh. 1980. Acute
and subchronlc toxldty of pentachlorobenzene. J. Environ. Pathol. Toxlcol.
4(5-6): 183-196.
Lingg, R.D., W.H. Kaylor, S.M. Pyle, et al. 1982. Comparative metabolism
of 1,2,4-tr1chlorobenzene 1n the rat and Rhesus monkey. Drug Metabol.
Dlspos. 10(2): 134-141.
Llssner, R., G. Gortz, M.G. Elchenauer and H. Ippen. 1975. Hexachloroben-
zene Induced prophyrla 1n rats. Relationship between porphyrln excretion
and Induction of drug metabolizing liver enzymes. Blochem. Pharmacol. 24:
1729-1731.
1837A 14-41 03/29/84
-------
Loose, L.O., K.A. PHtman, K.F. Benltz, J.B. Sllkworth, W. Mueller and F.
Coulston. 1978a. Environmental chemical-Induced Immune dysfunction.
Ecotoxlcol. Environ. Safety. 2(2): 173-198.
Loose, L.D., J.B. Sllkworth, K.A. PHtman, K.-F. Benltz and W. Mueller.
1978b. Impaired host resistance to endotoxln and malaria 1n polychlorlnated
blphenyl- and hexachlorobenzene-treated mice. Infect. Immun. 20(1): 30-35.
Lopez-Avlla, V., R. Northcutt, J. Onstot, M. Wlckham and S. Billets. 1983.
Determination of 51 priority organic compounds after extraction from stan-
dard reference materials. Anal. Chem. 55(6): 881-889.
Lowenheim, F.A. and M.K. Moran. 1975. Faith, Keys, and Clark's Industrial
Chemicals, 4th ed. Wlley-Intersdence, New York. p. 258-265.
Lu, P-Y. and R.L. Metcalf. 1975. Environmental fate and b1odegradab1Hty
of benzene derivatives as studied 1n a model aquatic ecosystem. Environ.
Health. Perspect. 10: 269-284.
Lunde, G. and A. Bjorseth. 1977. Human blood samples as Indicators of
occupational exposure to persistent chlorinated hydrocarbons. Scl. Total
Environ. 8(3): 241-246.
Lunde, G. and E.B. Ofstad. 1976. Determination of fat-soluble chlorinated
compounds 1n fish. Z. Anal. Chem. 282: 395-399.
1837A 14-42 03/29/84
-------
Macek, K.J., S.R. Petrocelll and B.H. Sleight, III. 1979. Considerations
1n assessing the potential for, and significance of, blotnagnlfIcation of
chemical residues 1n aquatic food chains. In: Aquatic Toxicology, L.L.
Marking and R.A. Klmerle, Ed. Am. Soc. Test. Mater, p. 251-268.
Mackay, 0. and A.W. Wolkoff. 1973. Rate of evaporation of low-solubility
contaminants from water bodies to atmosphere. Environ. Sc1. Technol.
7(7): 611-614.
MacKay, D., W.Y. Sh1u and R.P. Sutherland. 1979. Determination of air-
water Henry's Law constants for hydrophoblc pollutants. Environ. Sc1.
Technol. 13(3): 333-337.
MacKay, D., A. Bobra, D.W. Chan and W.Y. Sh1u. 1982. Vapor pressure corre-
lations for low-volatility environmental chemicals. Environ. Sd. Technol.
16(10): 645-649.
Mantel, N. and M.A. Schnelderman. 1975. Estimating "safe" levels, a haz-
ardous undertaking. Cancer Res. 35: 1379-1386.
Martin, H. and C.R. Worthing. 197/. Pesticide Manual, 5th ed. British
Crop Protection Council, England, p. 170.
Matthews, M.B. and S. Kato. 1979. The metabolism and disposition of halo-
genated aromatlcs. in: Ann N.Y. Acad. Sd., Vol. 320. Health Effects of
Halogenated Aromatic Hydrocarbons, Int. Symp., NY, June 24-27, 1978, W.J.
Nicholson and J.A. Moore, Ed. N.Y. Acad. Sd. p. 131-137.
1837A 14-43 03/29/84
-------
MCA (Manufacturing Chemists Association). 1974. Chemical safety data sheet
SO-54: Ortho-dlchlorobenzene. MCA, Washington, DC. (Cited 1n: U.S. EPA,
1980a)
McKlnney, J.D. L. F1shbe1n, C.E. Fletcher and W.F. Bartel. 1970. Electron-
capture gas chromatography of paradlchlorobenzene metabolites as a measure
of exposure. Bull. Environ. Contain. Toxlcol. 5(4): 354-361.
McLeese, D.W. and C.D. Metcalfe. 1980. Tox1c1t1es of eight organochlorlne
compounds 1n sediment and seawater to Crangon septemsplnosa. Bull. Environ.
Contam. Toxlcol. 25(6): 921-928.
Mehendale, H.M., M. Field and H.B. Matthews. 1975. Metabolism and effects
of hexachlorobenzene on hepatic mlcrosomal enzymes 1n the rat. J. Agrlc.
Food Chem. 23(2): 261-265.
Melancon, M.J. and J.J. Lech. 1980. Uptake, metabolism, and elimination of
14C-labeled 1,2,4-tr1chlorobcnzene In rainbow trout and carp. J. Toxlcol.
Environ. Health. 6(3): 645-658.
Mendoza, C.E., B.T. Collins, J.B. Shields and 6.W. Laver. 1978. Effects of
hexachlorobenzene or hexabromobenzene on body and organ weights of prewean-
I1ng rats after a reciprocal transfer between the treated and control dams.
J. Agrlc. Food Chem. 26(4): 941-945.
1837A 14-44 03/29/84
-------
Mendoza, C.E., J.B. Shields and 6.W. Laver. 1979. Comparison of he por-
phyrlnogenlc activity of hexabromobenzene and hexachlorobenzene 1n pr1m1-
parous Wlstar rats. Bull. Environ. Contam. Toxlcol. 21(3): 358-364.
Merck and Company. 1978. Summary of monochlorobenzene bacterial mutagen
test (Ames test). OPTS, U.S. EPA, Washington, DC. TSCA Sec 8(d) submission
8DHQ-1078-0302.
MeMan, E. 1980. Legal limits of controls for volatile aromatic hydro-
carbons. Chemosphere. 9(5-6): N3-N6.
Mes, J. and D.J. Oavles. 1979. Presence of polychlorlnated blphenyl and
organochlorlne pesticides residues and the absence of polychlorlnated ter-
phenyls In Canadian human milk samples. Bull. Environ. Contam. Toxlcol.
21(3): 381-387.
Mes, J., D.J. Davles and D. Turton. 1982. Polychlorlnated blphenyl and
other chlorinated hydrocarbon residues 1n adipose tissue of Canadians.
Bull. Environ. Contam. Toxlcol. 28(1): 97-104.
Metcalf, R.L. 1977. Biological fate and transformation of pollutants 1n
water. In.: Fate of Pollutants 1n the A1r and Water Environments: Pt. 2.
Chemical and Biological Fate of Pollutants 1n the Environments, I.H. Suffet,
Ed. Wiley Series 1n Environ. Sd Technol., Vol. 8, John Wiley and Sons, New
York. p. 195-221.
1837A 14-45 03/29/84
-------
Meyer, J.R. 1948. Modification of mitosis by chemicals. Science.
108: 188.
Michael, L.C., M.D. Erlckson, S.P. Parks and E.G. Pell1zzar1. 1980. Vola-
tile environmental pollutants 1n biological matrices with a headspace purge
technique. Anal. Chem. 52(12): 1836-1841.
Mollner, T. 1983. Personal communication to Murlal M. Uppman, ERNACO,
Inc., Silver Springs, MD.
Monsanto Company. 1965. Biographies acute and subacute data n monochloro-
benzene (AME 20-079). OPTS, U.S. EPA, Washington, DC. TSCA Sec 8(d) sub-
mission 8DHQ-1078-0212(4). {Cited 1n: U.S. EPA, 1980a)
Monsanto Company. 196/a. 13-Week oral administration-dogs, monochloroben-
zene. OPTS, U.S. EPA, Washington, DC. TSCA Sec 8(d) submission
8DHQ-1078-0212(2).
Monsanto Company. 1967b. Three-month subacute oral study of monochloroben-
zene 1n rats. U.S. EPA, Washington, DC. TSCA Sec 8(d) submission
8DHQ-1078-Q212(3).
Monsanto Company. 1976. Litton B1onet1cs mutagenldty evaluation of
B1o-76-86-CP 5535 (WGK): Monochlorobenzene. OPTS, U.S. EPA, Washington, DC.
TSCA Sec 8(d) submission 8DHQ-1078-0214(1).
1837A 14-46 03/29/84
-------
Monsanto Company. 1978a. TSCA Sec 8{d) Submission 8DHQ-1078-0221(2).
Report on salmonella mutagenldty assay of m-dlchlorobenzene (technical).
OP1S, U.S. EPA, Washington, DC.
Monsanto Company. 1978b. Industrial B1o-Test draft report of 90-day sub-
acute vapor Inhalation toxldty study with monochlorobenzene, 1n beagle dogs
and albino rats. OPTS, U.S. EPA, Washington, DC. TSCA Sec 8(d) submission
8DHQ-1078-0212(1).
Montrose Chemical Corporation of California. 1972. Product safety Infor-
mation: Olchlorobenzene. February 1972. (Cited 1n: U.S. EPA, 1980a)
Morlta, M. 1977. Chlorinated benzenes 1n the environment. Ecotoxlcol.
Environ. Safety. 1(1): 1-6.
Morlta, M. and G. Oh1. 1975. Para-d1chlorobenzene 1n human tissue and
atmosphere 1n Tokyo metropolitan area. Environ. Pollut. 8(4): 269.-274.
Morlta, M. and G. Oh1. 1978. p-D1chlorobenzene in pigeon and human adipose
tissue. Chemosphere. 7(10): 839-842.
Morlta, M., T. N1sh1zawa and S. Mlmura. 1975a. Environmental pollution by
hexachlorobezene. Tokyo ToMtsu Eisel Kenkyusho Kenkyu Nempo. 26(1):
333-335. (Jap.) CA 85: 51355g. (CHed in: IARC, 1979)
1837A 14-47 03/29/84
-------
MorHa, M., F. Ushio, T. Nishlzawa, S. Fukano, M. Doguchl and S. Mlmura.
1975b. Hexachlorobenzene 1n foods. Shokuhln E1se1gaku Zasshl. 16: 53-54.
(Jap.)
MorUa, M., T. Nishlzawa, S. Mlmura, et al. 1975c. Envlrnmental pollution
by para-dlchlorobenzene. Tokyo TorHsu E1se1 Kenkyusho Kenkyu Nempo.
26(1): 329-332.
MorHa, M., S. Mlmura, G. Oh1, H. Yagyu and T. Nishlzawa. 1975d. A
systematic determination of chlorinated benzenes 1n human adipose tissue.
Environ. Pollut. 9(3): 175-179.
Morley, A., D. Geary and F. Harben. 1973. Hexachlorobenzene pesticides and
porphyrla. Med. J. Aust. 1: 565.
Muller, W.F., W. Hobson, 6.B. Fuller, W. Knauf, F. Coulston and F. Korte.
1978. Endocrine effects of chlorinated hydrocarbons In Rhesus monkeys.
Ecotoxlcol. Environ. Safety. 2(2): 161-172.
Mumma, C.E. and E.W. Lawless. 1975. Survey of Industrial processing data.
Task I - Hexachlorobenzene and hexachlorobutadlene pollution from chloro-
carbon processes. Prepared by Midwest Res. Inst., under Contract No.
68-01-2105. EPA 560/3-75-003. NTIS PB 243 641.
Murphy, R.S., F.W. Kutz and S.C. Strassman. 1983. Selected pesticide resi-
dues or metabolites 1n blood and urine specimens from a general population
survey. Environ. Health. Perspect. 48: 81-86.
1837A 14 48 03/29/84
-------
Murray, H.E., G.S. Neff, Y. Hrung and C.S. G1am. 1980. Determination of
benzo(a)pyrene, hexachlorobenzene and pentachlorophenol 1n oysters from
Galveston Bay, Texas. Bull. Environ. Contam. Toxlcol. 25(4): 663-667.
Nakajlma, T. and A. Sato. 1979. Enhanced activity of liver drug-metaboliz-
ing enzymes for aromatic and chlorinated hydrocarbons following food depri-
vation. Toxlcol. Appl. Pharmacol. 50: 549-556.
Nalbandlan, R.M. and O.F. Pierce. 1965. Allergic purpura Induced by expo-
sure to p-d1chlorobenzene. J. Am. Med. Assoc. 194(7): 828-829.
NAS (National Academy of Sciences). 1977. Drinking Water and Health. Safe
Drinking Water Committee, NAS, Washington, DC. p. 667-673, 798-799.
NCI (National Cancer Institute). 1980. Bloassay of 2,3,7,8-tetrachlorodl-
benzo-p-d1ox1n. DHHS, Cardnogenesls Test. Prog., NIH, Bathesda, MD. Publ.
No. (NIH) 80-1765.
Neal, R.A. 1980. Metabolism of toxic substances. In.: Casarett and Doull's
Toxicology: The Basic Science of Poisons, 2nd ed., J. Doull, C. Klaassen and
M. Amour, Ed. MacMlllan Publishing Co., Inc., New York. p. 56-69.
Neely, W.B., D.R. Branson and G.E. Blau. 1974. Partition coefficient to
measure bloconcentratlon potential of organic chemicals In fish. Environ.
Sc1. Tech. 8(13): 1113-1115.
1837A 14-49 03/29/84
-------
Neptune, D. 1980. Descriptive statistic for detected priority pollutants
and tabulation listings. Off. Water Plan. Stand., U.S. EPA, Washington, DC.
TRDB-0280-001.
N11m1, A.J. and C.Y. Cho. 1980. Uptake of hexachlorobenzene (HCB) from
feed by rainbow trout (Salmo galrdnerl). Bull. Environ. Contain. Toxlcol.
24(6): 834-839.
N11m1, A.J. and C.Y. Cho. 1981. Elimination of hexachlorobenzene (HCB) by
rainbow trout (Salmo galrdnerl). and an examination of Us kinetics 1n Lake
Ontario salmonlds. Can. J. F1sh Aquatic Sc1. 38: 1350-1356.
NISOH (National Institute for Occupational Safety and Health. 1977. NIOSH
Manual of Analytical Methods, 2nd ed., Vol. 1-5. Cincinnati, OH. Publ. No.
77-157-A. p. S133-1 to S133-8, S281-1 to S281-9, S135-1 to S135-9.
NIOSH (National InstutHe for Occupational Safety and Health). 1978. Cri-
teria for a Recommended Standard...Occupational Exposure During the Manu-
facture and Formulations of Pesticides. Cincinnati, OH. OHEW (NIOSH) Publ.
No. 78-174.
NIOSH (National Institute for Occupational Safety and Health). 1982. The
1982 Registry of Toxic Effects of Chemical Substances. R.J. Lewis and R.L.
Taken, Ed. Cincinnati, OH.
NLM (National Library of Medicine). 1979a. Hexachlorobenzene. Toxicology
Data Base, Bethesda, MD. TDB No. 1724.
1837A 14-50 03/29/84
-------
NLM (National Library of Medicine). 1979b. 1,2,3,4,5-Pentachlorobenzene.
Toxicology Data Base, Bethesda, MD. TDB No. 2863. .
NLM (National Library of Medicine). 1980. 1,2-D1chlorobenzene. Toxi-
cology Data Base, Bethesda, MD. TDB No. 0521.
NLM (National Library of Medicine). 1981a. 1,3-D1chlorobenzene. Toxi-
cology Data Base, Bethesda, MD. TDB No. 0523.
NLM (National Library of Medicine). 1981b. 1,4-D1chlorobenzene. Toxi-
cology Data Base, Bethesda, MD. TDB No. 0523.
NLM (National Library of Medicine). 1981c. 1,2,3,4-Tetrachlorobenzene.
Toxicology Data Base, Bethesda, MD. TDB No. 4268.
NLM (National Library of Medicine). 1981d. 1,2,3,5-Tetrachlorobenzene.
Toxicology Data Base, Bethesda, MD. TDB No. 4269.
NLM (National Library of Medicine). 1981e. 1,2,3-Tr1chlorobenzene. Toxi-
cology Data Base, Bethesda, MD. TDB No. 1502.
NLM (National Library of Medicine). 1981f. 1,2,4-Trichlorobenzene. Toxi-
cology Data Base, Bethesda, MD. TDB No. 1105.
NLM (National Library of Medicine). 1982a. Chlorobenzene. Toxicology Data
Base, Bethesda, MD. TDB No. 0055.
1837A 14-51 03/29/84
-------
NLM (National Library of Medicine). 1982b. 1,2,4,5-Tetrachlorobenzene.
Toxicology Data Base, Bethesda, MD. TOB No. 2733.
NLM (National Library of Medicine). 1982c. 1,3,5-Tr1chlorobenzene. Toxi-
cology Data Base, Bethesda, MD. TDB No. 0132.
Nojlma, K. and S. Kanno. 1980. Studies on photochemistry of aromatic
hydrocarbons. VII. Photochemical reaction of p-d1chlorobenzene with nitro-
gen oxides In air. Chemosphere. 9(7-8): 437-440.
Noren, K. 1983. Some aspects of the determination of organochlorlne con-
taminants In human milk. Arch. Environ. Contam. Toxlcol. 12: 277-283.
Norstrom, R.J., D.J. Hallett and R.A. Sonstegard. 1978. Coho salmon
(Qncorhynchus klsutch) and herring gulls (Larus argentatus) as Indicators of
organochlorlne contamination 1n Lake Ontario. J. F1sh Res. Board Can.
35(11): 1401-1409.
NIP (National Toxicology Program). 1982. Cardnogenesls bloassay of
l,2-d1chlorobenzene (CAS No. 95-50-1) in F344/N rats and B6C3F1 mice
(gavage study). NTP, Research Triangle Park, NC. NTP-82-062. NIH Publ.
No. 82-2511. (Draft)
NIP (National Toxicology Program). 1983a. NTP Technical report.
NTP-82-062. p. 11.
1837A 14-52 03/29/84
-------
NTP (National Toxicology Program). 19835. Carc1nogenes1s bloassay of
chlorobenzene (CAS No. 108-90-7) 1n F344/N rats and B6C3F mice (gavage
study). NTP-82-090. NIH Publ. No. 83-2517. (Draft)
Oehme, M. and H. Stray. 1982. Quantitative determination of ultra-traces
of chlorinated compounds 1n high-volume air samples from the Arctic using
polyurethane foam as collection medium. Fresenlus Z. Anal. Chem. 311(7):
665-673.
Oesch, F.t D.M. JeMna, J.W. Daly and J.M. R1ce. 1973. Induction, activa-
tion, and Inhibition of epoxlde hydrase: An anomalous prevention of chloro-
benzene-lnduced hepatotoxiclty by an Inhibitor of epoxlde hydrase. Chem.
B1ol. Interact. 6: 189-202.
Ofstad, E.B., G. Lunde and K. Martlnsen. 1978. Chlorinated aromatic hydro-
carbons In fish and from an area polluted by Industrial effluents. Sd.
Total Environ. 10(3): 219-230.
Ogata, M. and Y. Shlmada. 1982. Differences In urinary monochlorobenzene
metabolites between rats and humans. Acta Med. Okayama. 36(6): 491 494.
Ogata, M., T. Hasegawa, T. Meguro and T. Mori. 1981. Effects of chlori-
nated monoaromatlc hydrocarbons on mltochondrlal oxldatlve phosphorylatlon
1n rat liver. Ind. Health. 19(1): 31-36.
Ohlendorf, H.M., D.M. Swlneford and L.N. Locke. 1981. OrganochloMne resi-
dues and mortality 1n herons. Pestle. Monlt. J. 14(4): 125-135.
1837A 14-53 03/29/84
-------
Oliver, B.G. and K.D. Nlcol. 1982. Chlorobenzenes 1n sediments, water and
selected fish from Lakes Superior, Huron, Erie and Ontario. Environ. Sc1.
Technol. 16(8): 532-536.
Oliver, B.G. and A.J. N11m1. 1983. Bloconcentratlon of Chlorobenzenes from
water by rainbow trout: Correlations with partition coefficients and envi-
ronmental residues. Environ. Sd. Technol. 17(5): 287-291.
Oliver, B.G., E.G. Cosgrove and J.H. Carey. 1979. Effect of suspended
sediments on the photolysis of organlcs 1n water. Environ. Sc1. Technol.
13(9): 1075-1077.
ORVWSC (Ohio River Valley Water Sanitation Commission). 1982. Assessment
of Water Quality Conditions. Ohio River Main Stem., 1980-1981, Cincinnati,
OH.
Otson, R. and D.T. Williams. 1982. Headspace chromatographlc determination
of water pollutants. Anal. Chem. 54(6): 942-946.
Otson, R., D.T. Williams and P.O. Bothwell. 1982. Volatile organic com-
pounds 1n water at thirty Canadian potable water treatment facilities. J.
Assoc. Off. Anal. Chem. 65(6): 1370-1374.
Pagnotto, L.D. and J.E. Walkley. 1966. Urinary dlchlorophenol as an Index
of para-dlchlorobenzene exposure. Ind. Hyg. Assoc. J. 26: 137-142.
1837A 14-54 03/29/84
-------
Paradl, E. and M. Lovenyak. 1981. Studies on genetlcal effect of pesti-
cides 1n Drosophlla melanogaster. Acta. B1ol. Acad. Sd. Hung. 32(2):
119-122. (Cited 1n: CA 96:156985t)
Parasher, C.D., M. Ozel and F. Gelke. 1978. Effect of hexachlorobenzene
and acetone on algal growth: Physiology and ultrastructure. Chem. B1ol.
Interact. 20(1): 89-95.
Parke, D.V. and R.T. Williams. 1955. Studies 1n detoxlcatlon. LXIII. The
metabolism of halogenobenzenes. (a) Meta-d1chlorobenzene. (b) Further
observations on the metabolism of chlorobenzene. Blochem. J. 59: 415-422.
Parke, D.V. and R.T. Williams. 1960. Studies 1n detoxlcatlon. LXXXI. The
metabolism of halogenobenzenes: (a) penta- and hexa-chlorobenzenes, and (b)
further observations on 1,3,5-tr1chlorobenzene. Blochem. J. 74: 5-9.
Parrlsh, P.R., G.H. Cook and J.M. Patrick, Jr. 1974. Hexachlorobenzene:
Effects on several estuarlne animals. In.: Proc. 28th Annual Conf. S.E.
Assoc. Game F1sh Comm. p. 179-187.
Parrlsh, P.R., E.E. Dyar, J.M. Enos and W.G. Wilson. 1978. Chronic toxl-
dty of chlordane, tr1flural1n, and pentachlorophenol to sheepshead minnows
(Cyprlnodon vaMeqatus). U.S. EPA, Gulf Breeze, FL. NTIS PB-278 269.
p. 67.
1837A 14-55 03/29/84
-------
Parsons, L.D. 1942. On early tumour formation 1n the pure-line mice
treated with carcinogenic compounds and the associated blood and tissue
changes. J. Path. Bact. 54: 321-330.
PelUzzarl, E.D., M.D. Erlckson and R.A. Zwe1d1nger. 1979. Formulation of
a preliminary assessment of halogenated organic compounds In man and envi-
ronmental media. OTS, U.S. EPA, Washington, DC. EPA 560/13-79-006. NTIS
PB 80-112170.
Pereira, M.S. 1983. Personal communication to Murlal M. Llppman, ERNACO,
Inc., Silver Springs, MD.
Pereira, M.S., S.L. Herren, A.L. BrUt and M. Khoury. 1982. Sex difference
In enhancement of GGTase-pos1t1ve fod by hexachlorobenzene and llndane 1n
rat liver. Cancer Lett. 15(1): 95-102.
Pereira, W.E. and B.A. Hughes. 1980. Determination of selected volatile
organic priority pollutants 1n water by computerized gas chromatography-
quadrupole mass spectrometry. J. Am. Water Works Assoc. 72(4): 220-230.
Perrln, M. 1941. Possible harmfulness of paradlchlorobenzene used as a
moth killer. Bull, de 1' Acad. de Med. 125: 302.
Peters, H., D. CMpps, J.T. Bryan and G. Gosman. 1983. 5th Annual Progress
Report of Ep1dem1olog1c Study of Populations Previously Exposed to Hexa-
chlorobenzene. EPA Contract 68-01-5002.
1837A H-56 03/29/84
-------
Peters, H.A., S.A.M. Johnson, S. Cam, et al. 1966. Hexachlorobenzene-
lnduced porphyrla: Effect of chelatlon of the disease, porphyMa and metal
metabolism. Am. J. Med. Sc1. 251: 314-322.
Peters, H.A., A. Gocmen, D.J. Crlpps, 6.T. Bryan and I. Dogramad. 1982.
Epidemiology of hexachlorobenzene-lnduced porphyrla 1n Turkey. Clinical and
laboratory follow-up after 25 years. Arch. Neurol. 39(12): 744-749.
Petit, G. and J. Champelx. 1948. Does an Intoxication caused by para-
dlchlorobenzene exist? Arch. Malad. Profess. Med. 9: 311-312.
Pickering, Q.H. and C. Henderson. 1966. Acute toxldty of some important
petrochemicals to fish. J. Water Pollut. Control Fed. 38(9): 1419-1429.
P1ke, M.H. 1944. Ocular pathology due to organic compounds. J. Michigan
State Med. Soc. 43: 581-584.
Plslaru, V. 1960. Mod1f1car1 cronaxlmetrlce 1n 1ntox1cat1a cronlca cu
benzen s1 monochlorobenzen. Iglena. 9: 127-135. (Cited 1n: U.S. EPA,
1980a)
Poland, A., J. Goldstein, P. Hlckman and V.W. Burse. 1971. A reciprocal
relationship between the Induction of 6-am1nolevul1n1c add synthetase and
drug metabolism produced by m-d1chlorobenzene. Blochem. Pharmacol. 20(6):
1281-1290.
1837A 14-57 03/29/84
-------
Powers, M.B., W.B. Coate and T.R. Lewis. 1975. Repeated topical applica-
tions of 1,2,6-trlchlorobenzene: Effects on rabbit ears. Arch. Environ.
Health. 30: 165-167.
Prasad, I. 1970. Mutagenlc effects of the herbicide 3',4'-d1chloroprop1o-
anH1de and Us degradation products. Can. J. M1crob1ol. 16: 369-372.
Prasad, I. and D. Pramer. 1968. Mutagenlc activity of some chloroanlUnes
and chlorobenzenes. Genetics. 60: 212-213. (Abstr.)
Preussman, R. 1975. Chemical carcinogens In the human environment. Hand.
Allg. Pathol. 6: 421-594.
Rao, K.S., K.A. Johnson and J.W. Henck. 1982. Subchronlc dermal toxldty
study of trIchlorobenzene 1n the rabbit. Drug. Chem. Toxlcol. 5(3):
249-263.
Reich, H. 1934. Puran (Monochlorobenzol)-Verg1ftung be1 elnem zweljahrlgen
K1nde. Schwe1zer1sche Med1z1n1sche Wachenschrlft. 64: 223-224.
Reid, W.D. 1973. Mechanism of renal necrosis Induced by bromobenzene or
chlorobenzene. Exp. Mol. Pathol. 19: 197-214.
Reid, W.D. and G. Krishna. 1973. Centrolobular hepatic necrosis related to
covalent binding of metabolites of halogenated aromatic hydrocarbons. Exp.
Mol. Pathol. 18: 80-99.
1837A 14-58 03/29/84
-------
Reid, W.D., B. Christie, M. Elchelbaum and G. Krishna. 1971. 3-Methyl-
choloanthrene blocks hepatic necrosis Induced by administration of bromoben-
zene or carbon tetrachlorlde. Exp. Mol. Pathol. 15(3): 363-372.
Reid, W.D., K.F. Ilett, J.M. Click and G. Krishna. 1973. Metabolism and
binding of aromatic hydrocarbons 1n the lung. Am. Rev. Res. D1s. 107:
539-551.
Renner, G. 1981. B1otransformat1on of the fungicides hexachlorobenzene and
pentachloronltrobenzene. Xenob1ot1ca. 11(7): 435-446.
Richardson, L.T. 1968. Selective vapor phase activity of chloronltro- and
chlorobenzene 1n soil. Phytopathology. 58: 316-322.
Rlchter, E. and S.G. Schaefer. 1981. Intestinal excretion of hexachloro-
benzene. Arch. Toxlcol. 47(3): 233-239.
Rlchter, E., G. Renner, J. Bayerl and M. W1ck. 1981. Differences 1n the
blotransformatlon of hexachlorobenzene (HCB) 1n male and female rats.
Chemosphere. 10(7): 779-785.
Rledel, H. 1941. E1nge beobachtungen uber orthodlchlorobenzol. Arch.
Gewerbepath. Gewerbehyg. 10: 546-549.
R1m1ngton, C. and G. Zlegler. 1963. Experimental porphyrla In rats Induced
by chlorinated benzenes. Blochem. Pharmacol. 12: 1387-1397.
1837A 14-59 03/29/84
-------
R1os de Molina, M.C., R. Walnstok de Calmanovld and L.C. San Martin de
V1ale. 1980. Investigations on the presence of porphyrlnogen carboxy-lyase
Inhibitor 1n the liver of rats Intoxicated with hexachlorobenzene. Int. J.
Blochem. 12(5-6): 1027-1032.
R1zzard1n1, M. and A.G. Smith. 1982. Sex differences 1n the metabolism of
hexachlorobenzene by rats and the development of porphyMa 1n females.
Blochem. Pharmacol. 31(22): 3543-3548.
Robinson, K.S., R.J. Kavlock, N. Chernoff and I.E. Gray. 1981. Multlgener-
atlon study of 1,2,4-tr1chlorobenzene 1n rats. J. Toxlcol. Environ. Health.
8(3): 489-500.
Rosenbaum, N.D., R.S. Block, S.N. Kremneva, S.L. Glnzburg and I.V.
PozharlskH. 1947. The use of chlorobenzene as a solvent from the point of
view of Industrial hygiene. G1g1ena 1 SanH. 12(1): 21-24. (Cited 1n:
U.S. EPA, 1980b)
Rosewell, K.T., O.C.G. Mu1r and B.E. Baker. 1979. Organochlorlne residues
In harp seal (Phagophllus groenlandlcus) tissues, Gulf of St. Lawrence,
1971, 1973. Pest. Monlt. J. 12(4): 189-192.
Rowe, V.K. 1975. Written communication. CUed 1n; U.S. EPA, 1980b.
Rozman, K., W. Mueller, F. Coulston and F. Korte. 1977. Long-term feeding
study of hexachlorobenzene 1n Rhesus monkeys. Chemosphere. 6(2-3): 81-84.
1837A 14-60 03/29/84
-------
Rozman, K., J. Williams, W.F. Mueller, F. Coulston and F. Korte. 1979.
Metabolism and pharmacoklnetlcs of pentachlorobenzene 1n the Rhesus monkey.
Bull. Environ. Contam. Toxlcol. 22(1-2): 190-195.
Rozman, K., T. Rozman and H. Grelm. 1981. Enhanced fecal elimination of
stored hexachlorobenzene from rats and Rhesus monkeys (Macaca mulatta) by
hexadecane or mineral oil. Toxicology. 22(1): 33-44.
Ruddlck, J.A., D.C. Vllleneuve, I. Chu, S. Kacew and V.E. Valli. 1981. A
transplacental and teratologlcal evaluation of tetrachlorobenzene Isomers 1n
the rat. Teratology. 23(2): 59A. (Abstr.)
Rush, G.F., J.H. Smith, K. Malta, et al. 1983. Perinatal hexachlorobenzene
toxldty 1n the mink. Environ. Res. 31: 116-124.
Sana, J.G. and R.H. Burrage. 1976. Residues of Undane and Us metabolites
1n eggs, chicks and body tissues of hen pheasants after ingestlon of Undane
carbon-14 via treated wheat seed or gelatin capsules. 0. Environ. Sc1.
Health Pestle., Food Contam. Agrlc. Wastes Bull. 1: 67-93.
Salamone, L. and A. Coppola. 1960. Changes 1n blood coagulation 1n experi-
mental subacute poisoning with p-d1chlorobenzene. Influence of some Upo-
trophlc factors. Folia. Med. 43: 259-266.
Sanborn, J.R., W.F. Chllders and l.G. Hansen. 1977. Uptake and elimination
of [14C] hexachlorobenzene (HCB) by the green sunflsh, Lepomls cyanellus
Raf_., after feeding contaminated food. J. Agrlc. Food Chem. 25(3): 551-553.
1837A 14-61 03/29/84
-------
Sarbhoy, R.K. 1980. Effect of paradlchlorobenzene on the somatic chromo-
somes and mitosis of Lens esculenta (L.) Moench. Cytologla. 45(3): 381-388.
Sasmore, D.P. and D. Palmer. 1981. Ninety-day study of Inhaled l,3,5-tr1-
chlorobenzene 1n rats. Prog. rep. Dept. Energy, Washington, DC. Rep. No.
UCRL-15396. NTIS PC A04/MF A01.
Sax, N.I. 1975. Dangerous Properties of Industrial Materials, 4th ed. Van
Nostrand Relnhold Co., New York. p. 348, 351.
Sax, N.I. 1979. Dangerous Properties of Industrial Materials, 5th ed. Van
Nostrand Relnhold Co., NY. p. 716.
Schoeny, R.S., C.C. Smith and J.C. Loper. 1979. Non-mutagen1c1ty for Sal-
monella of the chlorinated hydrocarbons Arochlor 1254, 1,2,4-tr1chloroben-
zene, mlrex and kepone. Mutat. Res. 68(2): 125-132.
Schwarzenbach, R.P., E. Molnar-Kublca, W. G1ger and S.G. Wakeham. 1979.
Distribution, residence time and fluxes of tetrachloroethylene and l,4-d1-
chlorobenzene In Lake Zurich, Switzerland. Environ. Sd. Techno!. 13(11):
1367-1373.
Sekita, H. M. Takeda, Y. SaHo and M. Uchlyama. 1980. Studies on analysis
of pesticide residues 1n foods. XXX. Identification of hexachlorobenzene
(HCB) residue 1n foods and drinking water by gas chromatography-mass spec-
trometry. Bull. Natl. Inst. Hyg. Sc1. (Tokyo). 98: 138-143.
1837A 14-62 03/29/84
-------
Selander, H.G., D.M. Jerlna and J.W. Daly. 1975. Metabolism of chloroben-
zene with hepatic mlcrosomes and solublUzed cytochrome P-450 systems.
Arch. Blochem. Blophys. 168: 309-321.
Shakelford, W.M. and L.H. Keith. 1976. Frequency of organic chemlclas 1n
water. Environ. Res. Lab., ORD, U.S. EPA, Atlanta, GA. EPA 600/4-76-062.
p. 65-71.
Sharma, A.K. and N.K. Bhattacharyya. 1956. Chromosome breakage through
para-dlchlorobenzene treatment. Cytologla. 21: 353-360.
Sharma, A.K. and S.K. Sarkar. 1957. A study on the comparative effect of
chemicals on chromosomes of roots, pollen mother cells and pollen grains.
Proc. Indian Acad. Sc1. Sect. B. 45(6): 288-293.
Sheldon, L.S. and R.A. H1tes. 1978. Organic compounds 1n the Delaware
River. Environ. Sc1. Technol. 12(10): 1188-1194.
Shelton, O.W. and L.J. Weber. 1981. Quantification of the joint effects of
mixtures of hepatotoxlc agents: Evaluation of a theoretical model 1n mice.
Environ. Res. 26(1): 33-41.
Shlmada, Y. 1981. Studies on monochlorobenzene polslonlng. I. Quantita-
tive determination of urinary metabolites (p-chlorophenylmercaptur1c acid
and conjugates of 4-chlorocatechol) of monochlorobenzene by high-performance
liquid chromatography. Okayame loakkal Zasshl. 93(5-6): 549-554.
1837A 14-63 03/29/84
-------
Sh1ra1 T., Y. Mlyata, K. Nakan1sh1, G. Murasakl and N. Ito. 1978. Hepato-
carc1nogen1c1ty of polychlorlnated terphenyl (PCT) 1n ICR mice and Us
enhancement by hexachlorobenzene (HCB). Cancer Lett. 4(5): 271-275.
S1klos1, C., N. Simon and F. Koszo. 1981. Effect of some hexachlorobenzene
catabolUes on the porphyMn metabolism of rats. Dermatosen Beruf. Umwelt.
29(2): 40-42.
Simmon, V.F., E.S. R1cc1o and M.V. Pelrce. 1979. I_n vitro microbiological
genotoxldty assays of chlorobenzene, m-d1chlorobenzene, o-d1chlorobenzene
and p-dlchlorobenzene. Contract No. 68-02-2947. ORD, U.S. EPA, Washington,
DC.
Simmons, P.O., D. Branson and R. Bailey. 1977. 1,2,4-Tr1chlorobenzene:
Biodegradable or not? Text. Chem. Color. 9(9): 211-213.
Simon, G.S., R.G. Tardlff and J.F. Borzelleca. 1979. Failure of hexa-
chlorobenzene to Induce dominant lethal mutations 1n the rat. Toxlcol.
Appl. Pharmacol. 47(2): 415-419.
Singh, H.B., L.J. Salas, A. Smith and H. Sh1ge1sh1. 1979. Atmospheric mea-
surements of selected toxic organic chemicals. EPA Grant No. 805990, Atmos.
Chem. Phy. Dept., Environ. Sc1. Res. Lab., U.S. EPA, Research Triangle Park,
NC. EPA 600/3-80-072. NTIS PB 80-198989.
1837A 14-64 03/29/84
-------
Singh, H.B., L.J. Salas, A.J. Smith and H. Shlgelshl. 1981. Measurements
of some potentially hazardous organic chemicals 1n urban atmospheres.
Atmos. Environ. 15(4): 601-612.
Skaare, J.U. 1981. Persistent organochlorlnated compounds 1n Norwegian
human milk 1n 1979. Acta. Pharmacol. Toxlcol. (Copenhagen). 49(5): 384-389.
Skaftason, J.F. and T. Johannesson. 1982. Organochlorlne compounds 1n
Icelandic lake trout and salmon fry: Local and global sources of contamina-
tion. Acta Pharmacol. Toxlcol. 51(4): 397-400.
Sllmak, K., P. Johnson and V. Hodge. 1980. Materials balance-task c.4
chlorobenzenes. OTS, Washington, DC. EPA-560/13-80-001.
Smith, A.G. and J. Cabral. 1980. Liver-cell tumors In rats fed hexachloro-
benzene. Cancer Lett. 11(2): 169-172.
Smith, C.C. 1979. Personal communication, April 10. (Cited 1n U.S. EPA,
1980b)
Smith, E.N. and G.P. Carlson. 1980. Various pharmacoklnetic parameters 1n
relation to enzyme-Inducing abilities of 1,3,4-tr1chlorobenzene and
1,2,4-trlbromobenzene. J. Toxlcol. Environ. Health. 6(4): 737-749.
Smith, J.R., B.A. Shaw and D.M. Foulkes. 1972. Mechanisms of mammalian
hydroxylatlon: Some novel metabolites of chlorobenzene. Xcnob1ot1ca.
2(3): 215-226.
1837A 14-65 03/29/84
-------
Smith, C.C., S.T. Cragg and G.F. Wolfe. 1978. Subacute toxldty of
1,2,4-trichlorobenzene (TCB) 1n subhuman primates. Fed. Proc. 37(3): 248.
Smith, A.G., J.E. Francis and F. De Matteis. 1980. Lobes of rat tissue
respond at different rates to challenge by dietary hexachlorobenzene.
Biochem. Pharmacol. 29(23): 3127-3131.
Springer, M.A. 1980. Pesticide levels, egg and eggshell parameters of
great horned owls. Ohio J. Sci. 80(4): 184-187.
SRI International. 1983. 1983 Directory of Chemical Procedures. United
States of America. SRI International, Menlo Park, CA. p. 1097.
Srivastava, L.M. 1966. Induction of mitotic abnormalities in certain
genera of Tribe Vicieae by paradichlorobenzene. Cytologia. 31: 166-171.
Stendell, R.C., E. Cromartie, S.N. Wiemeyer and J.R. Longcore. 1977.
Organochlorine and mercury residues in canvasback duck eggs, 1972-73. J.
Wildl. Manage. 41(3): 453-457.
Sullivan, T.M. 1981. Pharmacokinetics of inhaled chlorobenzene in the
Sprague-Oawley rat. Diss. Abstr. Int. B 1982, 42(11): 4346. 132 p.
Sullivan, T.M., G.S. Born, G.P. Carlson and W.V. Kessler. 1983. The phar-
macokinetics of inhaled chlorobenzene in the rat. Toxicol. Appl. Pharmacol.
(In press)
1837A 14-66 03/29/84
-------
Sumers, J., M. Fuhrman and A. Kelman. 1952. Hepatitis with concomitant
esophageal varlces following exposure to moth ball vapors. N.Y. State Med.
J. 52: 1048-1049.
Sundlof, S.M., A.J. Parker, J. Simon, J.L. Dorner and L.G. Hansen. 1981.
Sub-acute toxldty of hexachlorobenzene 1n female beagles, Including
electroencephalographlc changes. Vet. Hum. Toxlcol. 23(2): 92-96.
Sundlof, S.F., L.G. Hansen, G.D. Korltz and S.M. Sundlof. 1982. The phar-
macoklnetlcs of hexachlorobenzene 1n male beagles. Distribution, excretion,
and pharmacoklnetlc model. Drug Metab. Dlspos. 10(4): 371-381.
Szaro, R.C., N.C. Coon and E. Kolbe. 1979. Pesticide and PCB of common
elder, herring gull and Great Black-backed gull eggs. Bull. Environ.
Contam. Toxlcol. 22: 394-399.
Szymczynskl, G.A. and S.M. Wal1szewsk1. 1981. Comparison of the content of
the chlorinated pesticide residues 1n human semen, testicles and fat tis-
sues. Andrologla. 13(3): 250-252.
lakahashl, W., D. Sa1d1n, G. Takel and L. Wong. 1981. OrganochloMde
pesticide residues 1n human milk 1n Hawaii, 1979-80. Bull. Environ. Contam.
Toxlcol. 27(4): 506-511.
Tarkhova, L.P. 1965. Material for determining the maximum permissible con-
centration of chlorobenzol 1n the atmospheric air. G1g. SanH. 30: 327-333.
1837A 14-67 03/29/84
-------
Ten Berge, W.F. and M. Hlllebrand. 1974. Organochlorlne compounds 1n sev-
eral marine organisms from the North Sea and the Dutch Wadden Sea. Neth. J.
Sea Res. 8: 361-368.
TessaM, J.O. and E.P. Savage. 1980. Gas-I1qu1d chromatographlc determina-
tion of organochlorlne pesticides and polychlorlnated blphenyls 1n human
milk. J. Assoc. Off. Anal. Chem. 63(4): 736-741.
Thelss, J.C., G.D. Stoner, M.B. Sh1mk1n and E. Welsburger. 1977. Test for
cardnogenldty of organic contaminants of United States drinking waters by
pulmonary tumor response 1n strain A mice. Cancer Res. 37: 2717-2720.
Thompson, B.A., W.R. Davidson and A.M. Lovett. 1980. Applications of a
versatile technique for trace analysis: Atmospheric pressure negative chemi-
cal 1on1zat1on. Environ. Health Perspect. 36: 77-84.
lotaro, S. 1961. Serum transmlnase and aldolase activity 1n subacute
experimental Intoxication with p-d1chlorobenzene. Folia Med. 44: 586-594.
Totaro, S. and G. L1car1. 1964. Serum transamlnases 1n subacute poisoning
with p-d1chlorobenzene. Influence of some Hoptroplc factors. Folia Med.
5: 507-511.
Townsend, B.A. and G.P. Carlson. 1981. Effect of halogenated benzenes on
the toxldty and metabolism of malathlon, malaoxon, parathlon and paraoxon
1n mice. Toxlcol. Appl. Pharmacol. 60(1): 52-61.
1837A 14-68 03/29/84
-------
Treon, J. 1950. The toxldty of trichlorobenzene. KetteMng Lab., Univ.
of Cincinnati. (Unpubl. rep.) CUed 1n: Coate et al., 1977.
Tschudy, D.P. and H.L. Bonkowsky. 1972. Experimental porphyrla. Fed.
Proc. 31: 147-159.
U.S. EPA. 1975a. Analytical report New Orleans area water supply study.
Region VI, Dallas, TX. EPA 906/9-75-003.
U.S. EPA. 1975b. Preliminary assessment of suspected carcinogens 1n
drinking water. Interim report to Congress, June. Washington, DC. EPA
560/4-75-0033.
U.S. EPA. 1975c. Preliminary assessment of suspected carcinogens In drink-
Ing water. Report to Congress, December. Washington, DC. EPA 560/4-75-005.
U.S. EPA. 1977. Investigation of selected potential environmental contami-
nants: Halogenated benzenes. EPA 560/2-77-004.
U.S. EPA. 19/8. In-depth studies on health and environmental Impacts of
selected water pollutants. Contract No. 68-01-4646.
U.S. EPA. 1980a. TSCA Chemical Assessment Series, Assessment of Testing
Needs: Chlorinated Benzenes, Support Document for Proposed Health Effects
Test Rule. Toxic Substances Control Act: Sect. 4. OPTS, Washington, DC.
EPA 560/11-80-014.
1837A 14-69 03/29/84
-------
U.S. EPA. 1980b. Ambient Water Quality Criteria for Chlorinated Benzenes.
Environmental Criteria and Assessment Office, Cincinnati, OH. EPA
440/5-80-028. NTIS PB 81-117392.
U.S. EPA. 1980c. Laboratory data. Environ. Res. Lab., Duluth, MM.
(Unpubl.)
U.S. EPA. 1980d. Ambient Water Quality Criteria for Olchlorobenzenes.
Environmental Criteria and Assessment Office, Cincinnati, OH. EPA
440/5-80-039. NTIS PB 81-117509.
U.S. EPA. 1981. Computer printout: Chlorobenzenes production estimates.
CICIS Development System, TOPS-20. OTS, Washington, DC.
U.S. EPA. 1982a. Test methods: Methods of organic chemical analysis of
municipal and Industrial wastewater. J.E. Longbottom and J.J. Llchtenberg,
Ed. Environ. MonH. Sup. Lab., Cincinnati, OH. EPA 600/4-82-057.
U.S. EPA. 1982b. Effects of monochlorobenzene on the jin vitro Induction of
chromosomal aberrations 1n Chinese hamster ovary cells. Prepared by Bio-
assay Systems Corp.
U.S. EPA. 1983. Chlorinated benzenes aggregates derived from Information
reported under TSCA section 8(a). Preliminary assessment Information rule
(47 FR 26992) using the techniques for aggregating data described by 48 FR
27041. Off. Toxic Subst., Washington, DC.
1837A 14-70 03/29/84
-------
USITC (United States International Trade Commission). 1981. Synthetic
organic chemicals, United States production and sales, 1980. U.S. GPO.
USITC Pub, 1183.
Uyeta, M., S. Taue, K. Chlkasawa and M. Mazakl. 1976. Photoformatlon of
polychlorlnated blphenyls from chlorinated benzenes. Nature. 264: 583-584.
VanTassel, S., N. AmalfHano and R.S. Narang. 1981. Determination of
arenes and violate haloorganlc compounds 1n air at mlcrogram per cubic meter
levels by gas chromatography. Anal. Chem. 53(13): 2130-2135.
Varshavskaya, S.P. 1967a. Comparative toxlcologlcal characteristics of
chlorobenzene and dichlorobenzene (ortho- and para-isomers) 1n relation to
the sanitary protection of water bodies. Hyg. Sanlt. 33(10): 17-23.
Varshavskaya, S.P. 1967b. The hygienic standardization of mono- and
dlchlorobenzenes 1n reservoir waters. Nauch. Tr. Asplr. Ordln., Pervyl.
Mosk. Med. Inst. p. 175-177. (Trans.)
Velth, G.D., D.L. DeFoe and B.V. Bergstedt. 1979. Measuring and estimating
the bloconcentratlon factor of chemicals 1n fish. J. F1sh. Res. Board Can.
36: 1040-1048.
1837A 14-71 03/29/84
-------
Velth, G.D., K.J. Macek, S.R. Petrocelll and J. Carroll. 1980. An evalua-
tion of using partition coefficients and water solubility to estimate bio-
concentration factors for organic chemicals 1n fish. in: Aquatic Toxi-
cology, ASTM SIP 707, J.G. Eaton, P.R. ParMsh and A.C. HendMcks, Ed. Am.
Soc. Test. Mater, p. 116-129.
Verschueren, K. 1977. Handbook of Environmental Data on Organic Chemicals.
Von Nostrand Relnhold Co., New York.
Vllleneuve, O.C. and S.L. H1erl1hy. 1975. Placental transfer of hexa-
chlorobenzene 1n the rat. Bull. Environ. Contam. Toxlcol. 13: 489-491.
VUleneuve, D.C. and K.S. Khera. 1975. Placental transfer of halogenated
benzenes (pentachloro-, pentachloronltro-, and hexabromo-) 1n rats. Envi-
ron. Physlol. Blochem. 5(5): 328-331.
Vllleneuve, D.C. and W.H. Newsome. 1975. ToxUHy and tissue levels 1n
rats and guinea pigs following acute hexachlorobenzene administration.
Bull. Environ. Contam. Toxlcol. 14(3): 297-300.
Vllleneuve, D.C., L.G. Panoplo and O.L. Grant. 1974. Placental transfer of
hexachlorobenzene 1n the rabbit. Environ. Physlol. Blochem. 4: 112-115.
Vllleneuve, O.C., I. Chu, V.E.O. Valll, V.E. Secours and G.C. Becking.
1983. The comparative acute, subacute and subchronlc toxldty of three
tetrachlorobenzene cogeners 1n the rat. Tox1colog1st. 3(1): 115. (Abstr.)
1837A 14-72 03/29/84
-------
Vos, J.G., H.L. van der Maas, A. Musch and E. Ram. 1971. ToxIcHy of hexa-
chlorobenzene 1n Japanese quail and special reference to porphyrla, Hver
damage, reproduction, and tissue residues. Toxlcol. Appl. Pharmacol. 18:
944-957.
Vos, J.G., M.J. van Logten, J.G. Kreeftenberg and W. Kru1z1nga. 1979a.
Hexachlorobenzene-lnduced stimulation of the humoral Immune response 1n
rats. Ann. N.Y. Acad. Sc1. 320: 535-550.
Vos, J.G., M.J. van Logten, J.G. Kreeftenberg, P.A. Steerenberg and W.
Krulzinga. 1979b. Effect of hexachlorobenzene on the Immune system of rats
following combined pre- and postnatal exposure. Drug Chem. Toxlcol.
2(1-2): 61-76.
Ward, G.S., P.R. Parrlsh and R.A. R1gby. 1981. Early life stage toxldty
tests with a saltwater fish: Effects of eight chemicals on survival, growth,
and development of sheepshead minnows (Cyprlnodon vaMegatus). J. Toxlcol.
Environ. Health. 8(1-2): 225-240.
Ware, S.A. and W.L. West. 1977. Investigation of selected potential
environmental contaminants: Halogenated benzenes. Prepared by Ebon Research
Systems under Contract No. 68-01-4183. OTS, U.S. EPA, Washington, DC. EPA
560/2-77-004. NTIS PB 273 206. p. 297.
Watanabe, P.G., R.J. Kodba, R.E. Hefner, Jr., H.O. Yakel and B.K.J. Leong.
1978. Subchronlc toxldty studies of 1,2,4-tMchlorobenzene 1n experimental
animals. Toxlcol. Appl. Pharmacol. 45(1): 322-333.
1837A 14-73 03/29/84
-------
Watts, R.R., D.W. Hodgson, H.L. Christ and R.F. Moseman. 1980. Improved
method for hexachlorobenzene and mlrex determination with hexachlorobenzene
confirmation 1n adipose tissue: Collaborative study. J. Assoc. Off. Anal.
Chem. 63(5): 1128-1134.
Weast, R.C. 1979. Chemical Rubber Company (CRC) Handbook of Chemistry and
Physics, 60th ed. CRC Press, Inc., Boca Raton, FL. p. C-153, C-157,
C-170-171.
Weast, R.C., Ed. 1981. Handbook of Chemistry and Physics, 61st ed. CRC
Press, Inc., Cleveland, OH.
Welsburger, E. 1983. Personal communication to MuMal M. Llppman, ERNACO,
Inc., Silver Springs, MO.
Weller, R.W. and A.J. CrelUn. 1953. Pulmonary granulomatosls following
extensive use of paradlchlorobenzene. Arch. Intern. Med. 91: 408-413.
Westoo, G. and K. Noren. 1978. OrganochloMne contaminants 1n human milk,
Stockholm 1967-1977. Amblo. 7(2): 62-64.
White, D.H. 1979. Nationwide residues of organochlorlne compounds 1n
starlings (Sturnus vulgarls). 1976. Pest. MonH. J. 12(4): 193-197.
Whlttemore, A. 1978. Quantitative theories of cardnogenesls. Ijr.
Advances In Cancer Research, Vol. 27. Academic Press, New York, NY.
p. 55-58.
1837A 14-74 03/29/84
-------
WhHtemore, A. and B. Keller. 1978. Quantitative theory of cardnogenesls.
Soc. Ind. Appl. Math. Rev. 20: 1-30.
Wlckstrom, K., H. Pyysalo and M.A. S11mes. 1983. Levels of chlordane,
hexachlorobenzene, PCB and DDT compounds In Finnish human milk In 1982.
Bull. Environ. Contam. Toxlcol. 31: 251-256.
Wlemeyer, S.N., T.G. Lament and L.N. Locke. 1980. Residues of environ-
mental pollutants and necropsy data for Eastern United States ospreys,
1964-1973. Estuaries. 3(3): 155-167.
Williams, R.T. 1959. The metabolism of halogenated aromatic hydrocarbons.
In: Detox1cat1on Mechanisms, 2nd ed. John Wiley and Sons, New York.
p. 237-277.
Williams, R.T. 1959. The Metabolism of Halogenated Aromatic Hydrocarbons.
Detox1cat1on of Mechanisms, 2nd ed. John Wiley and Sons, Inc., NY. p. 237.
Williams, R.T., P.C. Hirom and A.G. Renwlck. 1975. Species variation 1n
the metabolism of some organic halogen compounds. In: Ecological and Tox1-
cologlcal Research, A.D. Mclntyre and C.F. Mills, Ed. Plenum Press, New
York. p. 91-106.
Wilson, J.T., C.G. Enfleld, W.J. Dunlap, R.L. Cosby, D.A. Foster and L.B.
Baskin. 1981. Transport and fate of selected organic pollutants 1n a sandy
soil. J. Environ. Qual. 10(4): 501-506.
1837A 14-75 03/29/84
-------
Woj1nsk1, S., D. Clayton and J. Bumgarner. 1979. Analysis of volatile
organic constituents 1n ambient air at Henderson-Las Vega, Nevada;
Henderson, Nevada cloud study. ORO, U.S. EPA, Research Triangle Park, NC.
Yalkowsky, S.H. and S.C. Valvanl. 1980. Solubility and partitioning. I.
Solubility of nonelectrolytes 1n water. J. Pharm. Sci. 69(8): 912-922.
Yamamoto, H., Y. Ohno, K. Nakamorl, T. Okuyama, S. Ima1 and Y. Tsubura.
1957. Chronic toxldty and cardnogenlcHy test of 1,2,4-tr1chlorobenzene
on mice by dermal painting. J. Nara. Med. Assoc. 33: 132-145. (Jap.)
Yang, K.H., R.E. Peterson and J.M. Fujlmoto. 1979. Increased bile duct-
pancreatic fluid flow 1n benzene and halogenated benzene-treated rats.
Toxlcol. Appl. Pharmacol. 47(3): 505-514.
Yang, R.S.H., K.A. PHtman, D.R. Rourke and V.B. Stein. 1978. Pharmaco-
klnetlcs and metabolism of hexachlorobenzene 1n the rat and the rhesus
monkey. J. AgMc. Food Chem. 26(5): 1076-1083.
Young, O.R. and T.C. Heesen. 1978. DDT, PCB, and chlorinated benzenes 1n
the marine ecosystem off southern California. In: Water ChloMnatlon.
Environmental Impact and Health Effects, Vol. 2., R.L. Jolley, H. Gorchev
and D.H. Hamilton, Jr., Ed. Ann Arbor Science Publishers, Inc., Ann Arbor,
MI. p. 267-290.
1837A 14-76 03/29/84
-------
Zablk, M.E. and R. Schemmel. 1980. Influence of diet on hexachlorobenzene
accumulation 1n Osborne-Mendel rats. J. Environ. Pathol. Toxlcol. 4(5-6):
97-103.
Zapata-Gayon, C., N. Zapata-Gayon and A. Gongalez-Anguio. 1982. Clasto-
genlc chromosomal aberrations 1n 26 Individuals accidentally exposed to
ortho dlchlorobenzene vapors 1n the National Medical Center In Mexico City.
Arch. Environ. Health. 37(4): 231-235.
ZHko, V. 1976. Levels of chlorinated hydrocarbons 1n eggs of double-
crested cormorants from 1971 to 1975. Bull. Environ. Contain. Toxlcol.
16(4): 399-405.
Z1tko, V. and 0. Hutzlnger. 1976. Uptake of chloro- and bromoblphenyls,
hexachloro- and hexabromobenzene by fish. Bull. Environ. Contam. Toxlcol.
16(6): 665-673.
Zitko, V. and R.L. Saunders. 1979. Effect of PCBs and other organochlorine
compounds on the hatchabllity of Atlantic salmon (Salmo salar) eggs. Bull.
Environ. Contam. Toxlcol. 21(1-2): 125-130.
Zupko, A.G. and L.D. Edwards. 1949. A toxlcologlcal study of p-dichloro-
benzene. J. Am. Pharmaceut. Assoc. 38(3): 124-131.
1837A 14-77 03/29/84
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APPENDIX A
Comparison Among Different Extrapolation Models
Four models used for low-dose extrapolation, assuming the Independent
background, are:
Multistage: P(d) = 1 - exp [-(q^ + ... + qkdk)]
where q. are non-negative parameters.
A + B ln(d)
ProbH: P(d) = J f(x) dx
- 00
where f(.) 1s the standard normal probability density function.
Welbull: P{d) = 1 - exp [-bdk]
where b and k are non-negative paramters.
One-hit: P(d) = 1 - exp [-bd]
where b 1s a non-negative parameter.
The maximum likelihood estimates (MLE) of the parameters 1n the
multistage and one-hit models are calculated by means of the program
GLOBAL82, which was developed by Howe and Crump (1982). The MLE estimates
of the parameters 1n the probH and Welbull models are calculated by means
of the program RISK81, which was developed by Kovar and Krewskl (1981).
Table A-l presents the MLE of parameters 1n each of the four models.
1876A A-l 03/30/84
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TABLE A-l
Maximum Likelihood Estimate of the Parameters for Each of the Four Extrapolation Models
Based on Hepatocellular Carcinomas 1n Female Rats*
(mg/kg/day)
Basis of Interspecies
Extrapolation
Body weights
Body surface area
Multistage
qi - 2.20 x 10"1
q2 = 5.01 x 10~5
q-| = 1.35
q2 = 1.90 x 10"3
Probit
A = -1.35
8 = 1.12
A = 6.70 x 10"1
B = 1.12
Weibull One-hit
b = 2.20 x 10'1 b = 2.20 x 10'1
k = 1.00
b - 1.35 b = 1.35
k - 1.00
*Source: Lambrecht, 1983
o
CO
CO
oo
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