United States
Environmental Protection
Agency
Office of Research and
Development
Washington DC 20460
EPA/600/R-00/099
March 2001
v>EPA
US EPAOflice olJteieatai and Development
Sources, Emission and
Exposure for
Trichloroethylene (TCE) and
Related Chemicals
-------
EPA/600/R-00/099
March 2001
SOURCES, EMISSION AND EXPOSURE FOR
TRICHLOROETHYLENE (TCE)
AND RELATED CHEMICALS
National Center for Environmental Assessment-Washington Office
Office of Research and Development
U.S. Environmental Protection Agency
Washington, DC 20460
-------
DISCLAIMER
This report has been reviewed in accordance with U.S. Environmental Protection Agency
policy and approved for publication. Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.
11
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TABLE OF CONTENTS
LIST OF TABLES x
LIST OF FIGURES xi
PREFACE xii
AUTHORS, CONTRIBUTORS, AND REVIEWERS xiii
SECTION A. SUMMARY AND INTRODUCTION 1
SUMMARY 1
INTRODUCTION 10
SECTION B. PARENT COMPOUNDS 13
1.0 TRICHLOROETHYLENE 13
1.1 CHEMICAL AND PHYSICAL PROPERTIES 13
1.1.1 Nomenclature 13
1.1.2 Formula and Molecular Weight 13
1.1.3 Chemical and Physical Properties 13
1.1.4 Technical Products and Impurities 14
1.2 PRODUCTION AND USE 14
1.2.1 Production 14
1.2.2 Uses 14
1.2.3 Disposal 15
1.3 POTENTIAL FOR HUMAN EXPOSURE 15
1.3.1 Natural Occurrence 15
1.3.2 Occupational Exposure 15
1.3.3 Environmental 15
1.4 HUMAN EXPOSURE AND POPULATION ESTIMATES 23
1.4.1 General U.S. Population 23
1.4.2 Occupational Exposure 26
1.4.3 Consumer Exposure 27
1.5 CHAPTER SUMMARY 27
2.0 TETRACHLOROETHYLENE (PERCHLOROETHYLENE) 30
2.1 CHEMICAL AND PHYSICAL PROPERTIES 30
2.1.1 Nomenclature 30
2.1.2 Formula and Molecular Weight 30
2.1.3 Chemical and Physical Properties 30
2.1.4 Technical Products and Impurities 31
2.2 PRODUCTION AND USE 31
in
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TABLE OF CONTENTS (continued)
2.2.1 Production 31
2.2.2 Uses 32
2.2.3 Disposal 32
2.3 POTENTIAL FOR HUMAN EXPOSURE 32
2.3.1 Natural Occurrence 32
2.3.2 Occupational 32
2.3.3 Environmental 33
2.4 HUMAN EXPOSURE AND POPULATION ESTIMATES 40
2.4.1 General U.S. Population 40
2.4.2 Occupational Exposure 41
2.4.3 Consumer Exposure 41
2.5 CHAPTER SUMMARY 41
3.0 1,1,1-TRICHLOROETHANE (METHYL CHLOROFORM) 44
3.1 CHEMICAL AND PHYSICAL PROPERTIES 44
3.1.1 Nomenclature 44
3.1.2 Formula and Molecular Weight 44
3.1.3 Chemical and Physical Properties 44
3.1.4 Technical Products and Impurities 45
3.2 PRODUCTION AND USE 45
3.2.1 Production 45
3.2.2 Uses 46
3.2.3 Disposal 46
3.3 POTENTIAL FOR HUMAN EXPOSURE 46
3.3.1 Natural Occurrence 46
3.3.2 Occupational 46
3.3.3 Environmental 47
3.4 HUMAN EXPOSURE AND POPULATION ESTIMATES 52
3.4.1 General U.S. Population 52
3.4.2 Occupational Exposure 52
3.4.3 Consumer Exposure 54
3.5 CHAPTER SUMMARY 54
4.0 1,2-DICHLOROETHYLENE 56
4.1 CHEMICAL AND PHYSICAL PROPERTIES 56
4.1.1 Nomenclature 56
4.1.2 Formula and Molecular Weight 56
4.1.3 Chemical and Physical Properties 56
4.1.4 Technical Products and Impurities 57
4.2 PRODUCTION AND USE 57
4.2.1 Production 57
4.2.2 Uses 57
4.2.3 Disposal 58
4.3 POTENTIAL FOR HUMAN EXPOSURE 58
IV
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TABLE OF CONTENTS (continued)
4.3.1 Natural Occurrence 58
4.3.2 Occupational 58
4.3.3 Environmental 58
4.4 HUMAN EXPOSURE AND POPULATION ESTIMATES 62
4.4.1 General U.S. Population 62
4.4.2 Occupational Exposure 62
4.4.3 Consumer Exposure 64
4.5 CHAPTER SUMMARY 64
5.0 CIS-1,2-DICHLOROETHYLENE 65
5.1 CHEMICAL AND PHYSICAL PROPERTIES 65
5.1.1 Nomenclature 65
5.1.2 Formula and Molecular Weight 65
5.1.3 Chemical and Physical Properties 65
5.1.4 Technical Products and Impurities 66
5.2 PRODUCTION AND USE 66
5.2.1 Production 66
5.2.2 Uses 66
5.2.3 Disposal 67
5.3 POTENTIAL FOR HUMAN EXPOSURE 67
5.3.1 Natural Occurrence 67
5.3.2 Occupational 67
5.3.3 Environmental 67
5.4 HUMAN EXPOSURE AND POPULATION ESTIMATES 70
5.4.1 General U.S. Population 70
5.4.2 Occupational Exposure 70
5.4.3 Consumer Exposure 70
6.0 TRANS-1,2-DICHLOROETHYLENE 71
6.1 CHEMICAL AND PHYSICAL PROPERTIES 71
6.1.1 Nomenclature 71
6.1.2 Formula and Molecular Weight 71
6.1.3 Chemical and Physical Properties 71
6.1.4 Technical Products and Impurities 72
6.2 PRODUCTION AND USE 72
6.2.1 Production 72
6.2.2 Uses 72
6.2.3 Disposal 73
6.3 POTENTIAL FOR HUMAN EXPOSURE 73
6.3.1 Natural Occurrence 73
6.3.2 Occupational 73
6.3.3 Environmental 73
6.4 HUMAN EXPOSURE AND POPULATION ESTIMATES 76
6.4.1 General U.S. Population 76
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TABLE OF CONTENTS (continued)
6.4.2 Occupational Exposure 76
6.4.3 Consumer Exposure 76
7.0 1,1,1,2-TETRACHLOROETHANE 77
7.1 CHEMICAL AND PHYSICAL PROPERTIES 77
7.1.1 Nomenclature 77
7.1.2 Formula and Molecular Weight 77
7.1.3 Chemical and Physical Properties 77
7.1.4 Technical Products and Impurities 78
7.2 PRODUCTION AND USE 78
7.2.1 Production 78
7.2.2 Uses 78
7.2.3 Disposal 79
7.3 POTENTIAL FOR HUMAN EXPOSURE 79
7.3.1 Natural Occurrence 79
7.3.2 Occupational 79
7.3.3 Environmental 79
7.4 HUMAN EXPOSURE AND POPULATION ESTIMATES 81
7.4.1 General U.S. Population 81
7.4.2 Occupational Exposure 82
7.4.3 Consumer Exposure 82
7.5 CHAPTER SUMMARY 82
8.0 1,1-DICHLOROETHANE 83
8.1 CHEMICAL AND PHYSICAL PROPERTIES 83
8.1.1 Nomenclature 83
8.1.2 Formula and Molecular Weight 83
8.1.3 Chemical and Physical Properties 83
8.1.4 Technical Products and Impurities 84
8.2 PRODUCTION AND USE 84
8.2.1 Production 84
8.2.2 Uses 84
8.2.3 Disposal 84
8.3 POTENTIAL FOR HUMAN EXPOSURE 85
8.3.1 Natural Occurrence 85
8.3.2 Occupational 85
8.3.3 Environmental 85
8.4 HUMAN EXPOSURE AND POPULATION ESTIMATES 88
8.4.1 General U.S. Population 88
8.4.2 Occupational Exposure 88
8.4.3 Consumer Exposure 88
8.5 CHAPTER SUMMARY 90
SECTION C. METABOLITES OF TRICHLOROETHYLENE
AND PARENT COMPOUNDS 91
VI
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TABLE OF CONTENTS (continued)
9.0 CHLORAL 91
9.1 CHEMICAL AND PHYSICAL PROPERTIES 91
9.1.1 Nomenclature 91
9.1.2 Formula and Molecular Weight 91
9.1.3 Chemical and Physical Properties 91
9.1.4 Technical Products and Impurities 92
9.2 PRODUCTION AND USE 92
9.2.1 Production 92
9.2.2 Uses 93
9.2.3 Disposal 93
9.3 POTENTIAL FOR HUMAN EXPOSURE 93
9.3.1 Natural Occurrence 93
9.3.2 Occupational 93
9.3.3 Environmental 94
9.4 HUMAN EXPOSURE AND POPULATION ESTIMATES 96
9.4.1 General U.S. Population 96
9.4.2 Occupational Exposure 96
9.4.3 Consumer Exposure 96
9.5 CHAPTER SUMMARY 96
10.0 CHLORAL HYDRATE 98
10.1 CHEMICAL AND PHYSICAL PROPERTIES 98
10.1.1 Nomenclature 98
10.1.2 Formula and Molecular Weight 98
10.1.3 Chemical and Physical Properties 98
10.1.4 Technical Products and Impurities 99
10.2 PRODUCTION AND USE 99
10.2.1 Production 99
10.2.2 Uses 100
10.2.3 Disposal 100
10.3 POTENTIAL FORHUMAN EXPOSURE 100
10.3.1 Natural Occurrence 100
10.3.2 Occupational 100
10.3.3 Environmental 100
10.4 HUMAN EXPOSURE AND POPULATION ESTIMATES 102
10.5 CHAPTER SUMMARY 102
11.0 MONOCHLOROACETIC ACID 103
11.1 CHEMICAL AND PHYSICAL PROPERTIES 103
11.1.1 Nomenclature 103
11.1.2 Formula and Molecular Weight 103
11.1.3 Chemical and Physical Properties 103
11.1.4 Technical Products and Impurities 104
11.2 PRODUCTION AND USE 104
vn
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TABLE OF CONTENTS (continued)
11.2.1 Production 104
11.2.2 Uses 104
11.2.3 Disposal 104
11.3 POTENTIAL FOR HUMAN EXPOSURE 105
11.3.1 Natural Occurrence 105
11.3.2 Occupational 105
11.3.3 Environmental 105
11.4 HUMAN EXPOSURE AND POPULATION ESTIMATES 107
11.5 CHAPTER SUMMARY 107
12.0 DICHLOROACETIC ACID 109
12.1 CHEMICAL AND PHYSICAL PROPERTIES 109
12.1.1 Nomenclature 109
12.1.2 Formula and Molecular Weight 109
12.1.3 Chemical and Physical Properties 109
12.1.4 Technical Products and Impurities 110
12.2 PRODUCTION AND USE 110
12.2.1 Production 110
12.2.2 Uses 110
12.2.3 Disposal 110
12.3 POTENTIAL FOR HUMAN EXPOSURE 110
12.3.1 Natural Occurrence 110
12.3.2 Occupational 110
12.3.3 Environmental Ill
12.4 HUMAN EXPOSURE AND POPULATION ESTIMATES 112
12.4.1 General U.S. Population 112
12.4.2 Occupational Exposure 112
12.4.3 Consumer Exposure 112
12.5 CHAPTER SUMMARY 112
13.0 TRICHLOROACETIC ACID 113
13.1 CHEMICAL AND PHYSICAL PROPERTIES 113
13.1.1 Nomenclature 113
13.1.2 Formula and Molecular Weight 113
13.1.3 Chemical and Physical Properties 113
13.1.4 Technical Products and Impurities 114
13.2 PRODUCTION AND USE 114
13.2.1 Production 114
13.2.2 Uses 114
13.2.3 Disposal 115
13.3 POTENTIAL FOR HUMAN EXPOSURE 115
13.3.1 Natural Occurrence 115
13.3.2 Occupational 115
13.3.3 Environmental 115
Vlll
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TABLE OF CONTENTS (continued)
13.4 HUMAN EXPOSURE AND POPULATION ESTIMATES 118
13.4.1 General U.S. Population 118
13.4.2 Occupational Exposure 118
13.4.3 Consumer Exposure 118
13.5 CHAPTER SUMMARY 118
14.0 DICHLORO-VINYL CYSTEINE 119
REFERENCES 120
IX
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LIST OF TABLES
Table A-l. Summary of Potential Exposure Pathways and Potentially
Exposed Populations 5
Table A-2. Preliminary Dose Estimates of TCE and Related Chemicals 8
Table A-3. Summary of U.S. Production Data 9
Table 1-1. Annual Releases of Trichloroethylene in the U.S. (Ibs) 16
Table 1-2. Concentrations of Trichloroethylene in Ambient Air 17
Table 1-3 Mean TCE Air Levels Across Monitors by Year 18
Table 1-4 Mean TCE Air Levels Across Monitors by Land
Setting and Use (1985 to 1998) 18
Table 1-5 Modeled TCE Air Concentrations in Continental U.S. for 1990 18
Table 1-6. Concentrations of Trichloroethylene in Water 21
Table 1-7. TCE Levels in Whole Blood by Population Percentile 22
Table 1-8. Modeled Exposure Estimates for TCE 25
Table 1-9. Comparison of Measured and Modeled TCE Concentrations 25
Table 1-10. Trichloroethylene Summary 29
Table 2-1. Releases of Tetrachloroethylene (Ibs) 33
Table 2-2. Concentrations of Tetrachloroethylene in Ambient Air 34
Table 2-3. Concentrations of Tetrachloroethylene in Water 35
Table 2-4. Tetrachloroethylene Levels in Whole Blood by Population
Percentile 37
Table 2-5. Modeled Exposure Estimates for Tetrachloroethylene 38
Table 2-6. Comparison of Measured and Modeled Perchloroethylene
Concentrations 38
Table 2-7. Tetrachloroethylene (Perchloroethylene) Summary 43
Table 3-1. Releases of 1,1,1-Trichloroethane (Ibs) 47
Table 3-2. Level of 1,1,1-Trichloroethane in Food 49
Table 3-3. 1,1,1-Trichloroethane in Common Household Products 54
Table 3-4. 1,1,1-Trichloroethane (Methyl Chloroform) Summary 55
Table 4-1. 1,2-Dichloroethylene Summary 64
Table 7-1. 1,1,1,2-Tetrachloroethane Summary 82
Table 8-1. 1,1-Dichloroethane Summary 90
Table 9-1. Concentrations of Chloral (As Chloral Hydrate)
in Drinking Water in the United States 94
Table 9-2. Chloral Summary 97
Table 10-1. Chloral Hydrate Summary 102
Table 11-1. Release of Chloroacetic Acid (Ibs/yr) 105
Table 11-2. Monochloroacetic Acid Summary 108
Table 12-1. Concentrations of Dichloroacetic Acid in Water Ill
Table 12-2. Dichloroacetic Acid Summary 112
Table 13-1. Concentrations of Trichloroacetic Acid in Water 116
Table 13-2. Trichloroacetic Acid Summary 118
x
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LIST OF FIGURES
Figure A-l. Trichloroethylene, Related Parent Compounds,
and Their Metabolites 11
Figure 1-1. Modeled TCE Levels in Air from Cumulative
Exposure Project by Census Tract, New Jersey 19
Figure 1-2. Frequency of NPL Sites with Trichloroethylene Contamination 28
Figure 2-1. Concentration of Tetrachloroethylene in Blood at
Selected Population Percentiles 36
Figure 2-2. Frequency of NPL Sites with Tetrachloroethylene Contamination 42
Figure 3-1. Concentration of 1,1,1-Trichloromethane in Blood at
Selected Population Percentiles 50
Figure 3-2. Frequency of NPL Sites with 1,1,1-Trichlorom ethane Contamination 53
Figure 4-1. Frequency of NPL Sites with 1,2-Dichloroethene (Unspecified)
Contamination 63
Figure 8-1. Frequency of NPL Sites with 1,1-Dichloroethane Contamination 89
XI
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PREFACE
This document was based mostly on the report, "Sources, Emission and Exposure for
Trichloroethylene (TCE)" which was prepared in August 1997 by the Versar, Inc. of Springfield,
Virginia under U.S. Environmental Protection Agency (EPA) Contract No. 68-D5-0051.
Additional information was later added/updated, especially for the Trichloroethylene chapter.
This document is published as a state-of-the-science report on the exposure assessment of
TCE, its metabolites and other related chemicals known to produce similar metabolites. A
summary of much of the information contained in this report was also published in
Environmental Health Perspectives, Supplements, May 2000 and underwent the peer review
process required by the journal.
The scientific literature search for this assessment is generally current through January
1997, although a number of more recent publications on key topics have been included.
xn
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AUTHORS, CONTRIBUTORS, AND REVIEWERS
Authors
This report was prepared by Versar, Inc. of Springfield, VA, for the National Center for
Environmental Assessment-Washington Office (NCEA-W) of EPA's Office of Research and
Development. Dr. Chieh Wu (NCEA-W) served as the Work Assignment Manager for this
contract as well as a contributing author. John Schaum (NCEA-W) was also a contributing
author.
Reviewers
A summary of this report was published in Environmental Health Perspective, Volume
108, Supplement 2 in May 2000 by Wu and Schaum. This journal sponsored a peer review of
this article by their independent reviewers. Other reviewers of this document are listed below:
EPA reviewers:
Cheryl Scott
National Center for Environmental Assessment
Mike Dusetzina
Office of Air Quality Planning and Standards
External reviewers:
Dr. C.P. Huang
Chair and Distinguished Professor of Environmental Engineering
University of Delaware
Dr. Uwe Schneider
Environmental Quality Branch
Environment Canada
Dr. Mildred Williams-Johnson
Agency for Toxic Substances and Disease Registry
U.S. Department of Health and Human Services
Acknowledgments
The authors wish to thank Cheryl Scott and Mike Dusetzina for their review and
comments of the draft report, and Susan Perlin of NCEA-W and David Wong of George Mason
University for their assisstance in the use of the Geographic Information System (GIS) modeling
to map the air concentrations in New Jersey. The authors also would like to thank all the
reviewers for their time and efforts.
Xlll
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SECTION A. SUMMARY AND INTRODUCTION
SUMMARY
This report is an exposure assessment of Trichloroethylene (TCE), its metabolites, and
other chemical compounds known to produce identical metabolites. In addition to TCE, other
parent compounds considered here are 1,1,1-trichloroethane (methyl chloroform),
tetrachloroethylene (PCE or PERC), 1,2-dichloroethylene (cis-, trans-, and mixed isomers),
1,1,1,2-tetrachloroethane, and 1,1-dichloroethane. The metabolites are chloral, chloral hydrate,
monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, and dichloro-vinyl cysteine
(DCVC). Although listed here, no information was found for the metabolite, DCVC.
The parent compounds are used in many diverse manufacturing industries such as food
processing, textiles, wood products, furniture and fixtures, paper, printing and publishing,
chemicals, petroleum, rubber, leather, stone and clay, primary metals, fabricated metals,
industrial machinery, electronics, and transportation equipment. They are primarily used as
solvents, carriers, or extractants; in dry cleaning of textiles; in metal cleaning and degreasing; in
textile manufacturing; as insulating fluids/coolants; and as chemical intermediates. The
metabolites have more restricted uses in industry as chemical intermediates, herbicides, and
Pharmaceuticals.
The major routes of exposure for these chemicals are inhalation, ingestion, and dermal
absorption. The following paragraphs summarize available information concerning the general
population, occupational, and consumer exposure to these chemicals. A summary of the
potential exposure pathways and potential exposed populations for each chemical is presented in
Table A-l. Although inhalation seems to be the dominant route of exposure for most of the
chemicals, exposure can also occur through the ingestion of contaminated foods and drinking
water and through dermal contact (spills). Using media levels of the chemicals considered here,
one may predict the range of estimated exposures and the estimated range of daily doses. These
values are presented in Table A-2.
More research is needed to assess the exposure of these chemicals for the non-
occupational population (IARC, 1995; ATSDR, 1990, 1995, 1996a,b, 1997a,b). Most of the
monitoring data for humans are from occupational studies of specific workers exposed to the
chemical. Current data are needed for all chemicals for production, use in consumer products,
releases, and the efficiency of current disposal practices. Additionally, more data are needed on
the degradation of these chemicals in groundwater (specifically TCE, PCE, 1,1,1-trichloroethane,
and 1,2-dichloroethylene) and their rates of transformation in the soil. Current data to
characterize the levels of these chemicals in air, water, soil, and food also are needed. Current
monitoring data for these media will aid in the assessment of exposure for the general population,
especially persons living near waste sites. Biological monitoring data are also needed for
humans. Because TCE and PCE have been detected in breast milk samples (NHANES in, 1997)
of the general population, children ages 12 months and less who ingest breast milk may
potentially be exposed. Unspecified levels of TCE have been found in breast milk, however,
levels of PCE detected have ranged up to 43 jig/1 in the general population. According to NAS
1
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(1991), in 1989, the initiation of breast-fed newborn infants in the hospital was reported to 52.2
percent and by age 5-6 months, only 19.6 percent of the infants were breast-fed. Since some of
these chemicals (e.g., TCE and PCE) are present in soil, children may be exposed through
activities such as playing in or ingesting soil. Table A-3 presents the production data
(production, import, and export). As shown in this table, however, most of the production data
are old or non-existent.
Trichloroethylene
The general U.S. population is exposed via inhalation, ingestion, or dermal pathways.
The most important pathways appear to be inhalation of contaminated ambient air and ingestion
of contaminated drinking water. Because of pervasiveness of TCE in the environment, most
people are exposed to low levels of TCE. Occupational exposure results primarily from its use
as a degreasing or metal cleaning agent. Workers in the vapor degreasing industry are exposed to
the highest levels through inhalation. Consumers are exposed through their use of wood stains,
varnishes, finishes, lubricants, adhesives, typewriter correction fluid, paint removers, and
cleaners that contain TCE. Levels of TCE in consumer products appear to be declining.
Elevated exposure may occur to people living near waste facilities, those being exposed through
occupational activities, and residents of some urban and industrial areas where TCE-
contaminated media occur. Since TCE has been detected in breast milk, nursing infants may be
exposed via this pathway.
Tetrachloroethylene (Perchloroethylene; PCE)
The general U.S. population is exposed to PCE via inhalation and ingestion. The most
important pathways appear to be inhalation of contaminated ambient air (including indoor air)
and ingestion of contaminated drinking water. Dermal exposure does not appear to be important.
The greatest chance of exposure is occupational, primarily through inhalation, especially in the
dry cleaning industry. Consumers may be exposed through the use of adhesives, water
repellents, fabric finishes, spot removers, and wood cleaners. Since PCE has been detected in
breast milk, nursing infants may be exposed via this pathway.
1,14-Trichloroethane (methyl chloroform)
The general U.S. population is exposed to this chemical via inhalation of ambient air
(including indoor air). Exposure can also occur through ingestion of contaminated foods and
drinking water and through dermal contact. Exposure from commercial products may be more
significant than exposure resulting from industrial releases. Occupational exposure results from
degreasing, electric component manufacture, mixing and application of commercial resins, spray
painting and gluing. Occupational exposure is primarily through inhalation pathway. Consumers
are exposed via use of a wide variety of household products such as fingernail polish, paint
thinner, caulking compounds, paint removers, and antifreeze.
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1,2-Dichloroethylene (cis-, trans-, and mixed isomers)
The general U.S. population is exposed to this chemical via the inhalation of
contaminated ambient air and from ingestion of water from contaminated groundwater sources.
Potentially high exposures are possible to those living near production/processing facilities,
municipal wastewater sites, hazardous waste sites, and municipal landfills. The National
Institute for Occupational Safety and Health (NIOSH) estimates that a small number of workers
(about 275) are potentially exposed occupationally via an inhalation or dermal pathway to one or
both of the isomers. No data are available for consumer exposure.
l,l?l?2-Tetrachloroethane
The general U.S. population is exposed to this compound thorough the inhalation of
ambient air. No data are available for occupational exposures. Consumers are possibly exposed
through their use of paints and varnishes, but confirmatory data are not available.
1,1-Dichloroethane
The general U.S. population is exposed to this chemical via the inhalation of ambient air
and the ingestion of contaminated drinking water. Higher exposures may exist for persons living
near industrial and hazardous waste sites. Occupational exposure occurs primarily via inhalation
during manufacturing processes using 1,1,-dichloroethane as a chemical intermediate, solvent,
and component of fumigant formulations. No data are available for consumer exposure.
Chloral
The general U.S. population may be exposed to chloral from drinking chlorinated water
and from pharmaceutical use. Some occupational exposure may result from chloral's production
and manufacture. No data are available for consumer exposure.
Chloral hydrate
The general U.S. population may be exposed to chloral hydrate from drinking chlorinated
water and from pharmaceutical use. No data are available for consumer exposure.
Monochloroacetic acid
No data are available for general U.S. population, occupational, and consumer exposure.
Dichloroacetic acid
The general U.S. population is exposed to this compound to this chemical via ingestion of
chlorinated drinking water and chlorinated water in swimming pools. No data are available for
occupational and consumer exposure.
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Trichloroacetic acid
The general U.S. population is exposed to this chemical via the ingestion of contaminated
drinking water and foods. Occupational exposure may occur during the production and use of
trichloroacetic acid as a pesticide. No data are available for consumer exposure.
Dichloro-Vinyl Cysteine
There are no data for this chemical.
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Table A-l. Summary of Potential Exposure Pathways and Potentially Exposed Populations
Chemical
TCE
PCE
1,1,1-
Trichloroethane
Potential Exposure Pathway
Inhalation
/"
/"
/"
Ingestion
/
/
/
Dermal
/
/
/
Potentially Exposed Population
General
/
/
/
Occupational
/"
-401,000 U.S.
employees (1981-
83 survey)
/"
-450,000 workers
in the dry-cleaning
industry; 688,110
other employees
(1981-83 survey)
/
-2.5 x 106 workers
(1981-83 survey).
Subcategories
include nurses,
maids, janitors,
electricians,
electronics
workers, and
apparel industry.
Consumer Exposure
/
Likely from use of
consumer products
that contain TCE.
/
Many consumer
products such as spot
removers, inks, fabric
finishes have been
found to contain PCE.
/
Consumer products
such as paints, paint
thinners, caulking
compounds, fingernail
polish, paint
removers, and food
packaging adhesives
have been reported to
contain 1,1,1-
trichloroethane
People living near waste sites, in urban
and industrial areas with populations
living near military bases, and with
occupational populations who are
continuously exposed to elevated levels.
Exposure to the consumer population is
possible from use of consumer products.
Products that generally contain TCE
include (paint removers, adhesives, etc.).
Short-term exposure to high levels
include people using consumer products
containing TCE with inadequate
ventilation. TCE has been detected in
breast milk, so exposure to nursing
infants may occur.
Persons working in dry cleaning
industries and metal degreasing most
heavily exposed; people living with
workers in the dry cleaning industries;
other populations who may have
elevated exposures include people living
near hazardous waste facilities and
people using products containing PCE in
areas with inadequate ventilation. PCE
has been detected in breast milk, so
exposure to nursing infants may occur.
elevated exposures may occur to
populations in occupational categories
such as degreasing operations.
Remarks
Work is being conducted at
Rutgers University to
develop a model for
describing exposure from
TCE contaminated
groundwater living near
Superfund sites because of
its persistence in
groundwater.
Research addressing waste
treatment technology is
underway at Cornell
University. Studies at New
York Department of
Health.
Exposure may also occur
through inhalation from
visiting dry cleaners;
working in chemistry labs;
using household cleaners,
pesticides, and paints.
Exposure to general
population from use of
commercial products may
be more significant than
from industrial releases.
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Table A-l. Summary of Potential Exposure Pathways and Potentially Exposed Populations (continued)
Chemical
1,2-
Dichloroethylene
(cis-, trans-, and
mixed isomers)
1,1,2,2-
Tetrachloroethane
1 , 1 -Dichloroethane
Chloral and Chloral
Hydrate
Monochloroacitic
Acid
Dichloroacetic Acid
Potential Exposure Pathway
Inhalation
S*
s*
s
NA
Ingestion
/
__C
/
/
/c
/
Dermal
/
__
__
NA
/
Potentially Exposed Population
General
/
/
/
/
NA
/
Occupational
Occupational
exposure to -275
people (mixed
isomers and cis
isomer only; data
not available for
trans isomer)
Probably exposed
through inhalation
of contaminated
ambient air
Estimated at 715-
1,957 workers in
early 1980s.
Exposure primarily
from use of
chemical as
intermediate and
solvent in
manufacturing
processes
Approximately
2,757 employees
(1981-83 survey -
chloral only)
NA
Approximately
1,592 employees
(1981-83 survey)
Consumer Exposure
Reported uses are in
the manufacture of
Pharmaceuticals,
artificial pearls, and in
the extraction of oil
and fats from fish and
meat. However, these
data are old (1985)
and consumer
exposure data were
not available.
Reported use is
primarily a feed stock
in the production of
solvent. It is not
known if this is a
closed production
process.
NA
NA
NA
NA
People living near waste sites and
production/processing facilities and
persons with occupational exposure.
Reported uses are in the manufacture of
paints and varnishes. It is not known if
this use is current or if the products are
consumer or industrial products.
Persons living near industrial and
hazardous waste sites.
NA
NA
NA
Remarks
Difficult to distinguish
between the isomers using
standard method analyses.
General population exposed
via inhalation of ambient
air and ingestion of
contaminated water.
General population may be
potentially exposed from
drinking chlorinated water
and pharmaceutical use.
Chloral hydrate is used in
Pharmaceuticals.
General population
potentially exposed
through the ingestion of
chlorinated drinking water,
water in swimming pools,
and contaminated surface
water.
-------
Table A-l. Summary of Potential Exposure Pathways and Potentially Exposed Populations (continued)
Chemical
Trichloroacetic
Acid
Dichloro-vinyl
Cysteine
Potential Exposure Pathway
Inhalation
NA
Ingestion
/
NA
Dermal
/
NA
Potentially Exposed Population
General
/
NA
Occupational
Estimated
employees exposed
is 35, 124 (1981-83
survey)
NA
Consumer
NA
NA
Populations with Potentially High
Exposure
NA
NA
Remarks
General population exposed
through ingestion of
chlorinated drinking water
and contact with
chlorinated surface water
and ingestion of foods
contaminated with this
chemical.
NA
NA = Information not available.
/ = Possible exposure pathway.
a Believed to be most prominent route of exposure, according to available data.
b Population with the greatest chance of elevated exposure (for longer periods of time).
c Probable exposure pathway, but not confirmed.
OO
-------
Table A-2. Preliminary Dose Estimates of TCE and Related Chemicals
Chemical
rrichloroethylene
fetrachloroethylene (PERC)
1,1,1 -Trichloroethane
1 , 2-Dichloroethylene
Cis- 1 , 2-Dichloroethylene
1,1,1, 2-Tetrachloroethane
1 , 1 -Dichloroethane
Chloral
Vlonochloroacetic Acid
}ichloroacetic Acid
Frichloroacetic Acid
Population
General
General
Occupational
General
General
Occupational
General
General
General
General
General
General
General
General
General
General
General
General
General
Media
Air
Water
Air
Air
Water
Air
Air
Water
Air
Water
Air
Water
Air
Air
Water
Water
Water
Water
Water
Range of Estimated Adult
Exposures
(ug/day)
11-33
2-20
2,232 - 9,489
80 - 200
0.1-0.2
5,897-219,685
10.8-108
0.38-4.2
1 -6
2.2
5.4
0.5-5.4
142
4
2.47 - 469.38
0.02-36.4
2 - 2.4
10 - 266
8.56 - 322
Range of Adult Doses
(mg/kg/day)
1.57E-04-4.71E-04
2.86E-05 - 2.86E-04
3.19E-02- 1.36E-01
1.14E-03-2.86E-03
1.43E-06-2.86E-06
8.43E-02-3.14
1.54E-04-1.54E-03
5.5E-06-6.00E-05
1.43E-05-8.57E-05
3.14E-05
7.71E-05
7.14E-06-7.71E-05
2.03E -03
5.71E-05
3.53E-05-6.71E-03
2.86E-07-5.20E-04
2.86E-05-3.43E-05
1.43E-04-3.80E-03
1.22E-03 -4.60E-03
Data Sources
ATSDR(1997a)
ATSDR(1997a)
ATSDR(1997a)
ATSDR(1997b)
ATSDR(1997b)
ATSDR(1997b)
ATSDR(1995)
ATSDR(1995)
ATSDR(1996a)
ATSDR(1996a)
HSDB (1996)
HSDB (1996)
HSDB (1996)
ATSDR(1990)
ATSDR(1990)
HSDB (1996)
USEPA(1994)
IARC (1995)
IARC (1995)
-------
Table A-3. Summary of U.S. Production Data
Chemical
TCE
PCE
1,1,1 -Trichloroethane
1 , 2-Dichloroethylene
Cis- 1 , 2-Dichloroethylene
Trans- 1 , 2-Dichloroethylene
1, 1,2,2-Tetrachloroethane
1 , 1 -Dichloroethane
Chloral
Chloral Hydrate
Monochloroacetic Acid
Dichloroacetic Acid
Trichloroacetic Acid
Dichloro-vinyl Cysteine
U.S. Production Data (kilograms)
Production (yr)
1.17xl05(1981)
7.72 xlO7 (1985)
1.45 xlO8 (1991)
3.08 xlO8 (1985)
1.84xl08(1986)
2.14 xlO8 (1989)
1.60xl08 (1990)
1.08x10° (1991)
1.12xl08(1992)
1.23 xlO8 (1993)
3.64 xlO8 (1990)
3.13xl08(1992)
NA
5.0 xlO5 (1977 -captive
production)
NA
NA
NA
2.83x10' (1969)
2.27 xlO7 (1975)
1.14 x 107 (1972 - anhydrous)
5.9 xlO5 (1975)
3.5xl07(1978)
>6.81xl03(1982)
NA
>3.6xl03(1975)
>2.27xl03(1976)
NA
Import (yr)
1.98 xlO7 (1985)
1.70xl07(1982)
6.36 xlO7 (1985)
8.3x10" (1986)
4.54x10" (1981)
5.99x10' (1992)
9.08x10" (1993)
NA
NA
NA
NA
NA
1.02 xlO5 (1984)
2.83 x 10" (1972)
4.8x10" (1975)
5.41 xlO3 (1984)
1.25 xlO7 (1978)
1.35 xlO7 (1982)
NA
3.67x10' (1984)
NA
Export (yr)
1.06 xlO7 (1985)
2.47 xlO7 (1983)
9.84x10' (1985)
5.20 xlO7 (1990)
7.39 xlO7 (1991)
6.34 xlO7 (1992)
3.44 xlO7 (1993)
NA
NA
NA
NA
NA
Negligible (1972; 1975)
NA
Negligible (1993)
NA
8.6x10' (1984)
NA
NA = Not available.
Sources: HSDB, 1996; IARC, 1995.
-------
INTRODUCTION
This report summarizes currently available exposure related information about TCE, its
metabolites, and other parent compounds that produce these same metabolites. Thus, this
assessment is a departure from typical exposure assessment of a chemical in that it considers
exposure to metabolites as well as parent compounds. Exposure information is summarized for
the following 14 compounds:
• Trichloroethylene;
• The primary metabolites of trichloroethylene: dichloro-vinyl cysteine, chloral,
chloral hydrate, trichloroacetic acid, dichloroacetic acid, monochloroacetic acid;
and
• The primary parent compounds which produce the same metabolites as
trichloroethylene: tetrachloroethylene, methyl chloroform, 1,1,1,2-
tetrachloroethane, cis-l,2-dichloroethylene, trans-1,2-dichloroethylene, 1,2-
dichloroethylene, and 1,1-dichloroethane.
Not all possible metabolites of trichloroethylene and related parent compounds were
included in the scope of this document. The metabolites were limited to human metabolites that
are produced in the largest quantities and are most important in producing toxic effects. The
parent compounds were limited to those to which humans are most commonly exposed. The two
parent compounds of most importance were trichloroethylene and tetrachloroethylene, and the
two metabolites of most importance were trichloroacetic acid and dichloroacetic acid. These
four compounds were given the highest priority in terms of the level of effort spent in developing
this document.
Figure A-l shows the parent-metabolite relationships between the compounds covered in
this document. The actual pathways of metabolism are much more complicated than shown here
and it should be understood that this diagram is intended only to give the reader a general
understanding of which parent compounds lead to which metabolites. The key limitations of this
diagram are summarized below:
• The diagram does not include all metabolites of trichloroethylene.
• The diagram does not include all potential parent compounds which could lead to
the listed metabolites. For example, acetic acids are common metabolites of many
compounds.
• The diagram does not show the intricacies of the metabolic pathways. For
example, interconversion can occur between some metabolites, many reactions
include intermediate steps and the reactions can be affected by enterohepatic
circulation and renal reabsorption.
10
-------
Trichloroethylene
(TCE)
-o
Trichloroacetic
Acid
Chloral Hydrate
Chloral
Dichloroacetic
Acid
Monochloroacetic
Acid
Dichlorovinylcysteine
Trichloroethanol
Tetrachloroethylene
1—
1—
s
J
1,1-Dichloroethane
Methyl Chloroform
1,1,1,2-Tetrachloroethane
1,2-Dichloroethylene
Figure A-l. Trichloroethylene, Related Parent Compounds, and Their Metabolites
-------
• The diagram does not represent quantitative relationships (i.e., some metabolites
are produced in much higher quantities than others and concepts such as half-life
and reaction kinetics are not represented).
This report has drawn heavily on information presented in the 1995 International Agency
for Research on Cancer publication (IARC 1995) and profiles on several chemicals from the
Agency for Toxic Substances and Disease Registry (ATSDR 1990, 1995, 1996a, 1997a,b).
Additional informational sources include electronic literature searches, on-line searches of the
Hazardous Substances Data Base, and data retrievals from the U.S. EPA Toxic Release Inventory
(TRI).
This report is organized in three sections. Section A includes this introduction and
summary of the results. Section B summarizes readily available information on the physical-
chemical properties, production and use, potential for human exposure, and exposure and
population estimates for TCE and the other parent compounds. The final section, Section C,
summarizes the same exposure-related information for the TCE metabolites.
There are a number of limitations and uncertainties in this report that result primarily
from the lack of information and that much of the data are not current, although found in current
publications. It should be noted that monitored chemical levels presented in this report are
primarily for the United States. Information on most metabolites is relatively sparse and is
completely lacking for one chemical.
Research is needed to gather data, especially to confirm current production, use, release,
and disposal practices and study fate of the chemicals in certain media (especially groundwater
and soils). Reliable, current monitoring data for levels in environmental media are needed to
assess human exposures. Most of the monitoring data reported are old and based on occupational
studies data. Additionally, the monitoring data for humans are basically for levels in blood and
urine only. Research is needed to address monitored levels of these chemicals in other human
tissues for the general population and populations around hazardous waste sites as well.
12
-------
SECTION B. PARENT COMPOUNDS
1.0 TRICHLOROETHYLENE
1.1 CHEMICAL AND PHYSICAL PROPERTIES
The information/data presented in this section and the supporting references were
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).
1.1.1 Nomenclature
CAS No.:
Synonyms:
Trade Names:
79-01-6
l-chloro-2,2-dichloroethylene; ethene, trichloro-; acetylene
trichloride, TCE.
Chlorylea, Chlorylen, CirCosolv, Crawhaspol, Dow-Tri,
Dukeron, Per-A-Clor, Triad, Trial, TRI-Plus M, Vitran, Perm-A-
Chlor (and others).
1.1.2 Formula and Molecular Weight
Molecular Formula: C2HC13
Molecular Weight: 131.40
1.1.3 Chemical and Physical Properties
Description:
Boiling Point:
Melting Point:
Density:
Clear, colorless, or blue mobile liquid (Remington's Pharm. Sci.,
16th Ed., 1980); chloroform-like odor (Weast, 1986-87).
87° C (Weast, 1987-1988).
-73° C (Weast, 1987-1988).
1.4649 @ 20° C/4° C (Merck Index, 11th Ed., 1989).
Spectroscopy Data: Sadtler Ref. Number: 185 (IR, Prism); Max. Absorption: less
than 200 nm (vapor) (Weast, 1979); Index of refraction: 1.4773
@ 20° C/D (Weast, 1986-87); IR: 62 (Weast, 1979).
Solubility:
Volatility:
1,100 mg/1 water at 25° C (Verschueren, 1983).
Vapor Pressure: 19.9 mm Hg @ 0° C; 57.8 mm Hg @ 20° C
(NRC, 1981).
13
-------
Vapor Density: 4.53 (air = 1) (Merck Index, 1989).
Stability: Relatively stable in air (Browning, Tox Metab Indus Solv, 1965);
Unstable in light and moisture (Osal, 1980).
Reactivity: Incompatible with strong caustics and alkalis; chemically-active
metals such as barium, lithium, sodium, magnesium, titanium,
and beryllium (NIOSH Pocket Guide Chemical Hazards, 1994).
Octanol/Water
Partition Coefficient: log Kow = 2.29 (Hansch, 1979).
1.1.4 Technical Products and Impurities
Trichloroethylene is available in the USA in high-purity, electronic USP, technical, metal
degreasing, and extraction grades (IARC Monographs, 1972-present, V20, 1979). Commonly
used stabilizers found in commercial trichloroethylene products include: pentanol-2
triethanolamine, 2,2,4-trimethylpentene-l, and iso-butanol. Tetrachloroethane is a contaminant
in commercial trichloroethylene (ARENA, 1986). Impurities found in commercial
trichloroethylene products include: carbon tetrachloride, chloroform, 1,1,1,2-trichloroethane, and
benzene (WHO, 1985).
1.2 PRODUCTION AND USE
The information/data presented in this section and the supporting references were
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996) and IARC
(1995).
1.2.1 Production
U.S. Production: (1981) 1.17 x 108 g (USITC, 1981); (1985) 7.72 x 1010 g
estimated (USITC, 1985); (1991) 1.45 x 1011 g (SRI. Directory
Chem. Producers-USA, 1992).
Import Volume: (1985) 1.98 x 1010 g (Bureau of the Census, U.S. Imports, 1985).
Export Volume (1985) 1.06 x 1010 g (Bureau of the Census, U.S. Exports, 1985).
1.2.2 Uses
The major use of trichloroethylene is degreasing (IARC, 1995). About 85 percent of the
TCE produced is used in metal cleaning. Other uses include the manufacture of organic
chemicals; as a solvent in adhesives and paint-stripping formulations, paints, lacquers, varnishes;
heat transfer medium-EG; in case hardening of metals; a solvent base for metal phosphatizing
systems; and solvent in characterization test for asphalt (SRI). It was also used earlier as an
extractant for spice oleoresins, natural fats and oils, hops and decaffeination of coffee (IARC,
14
-------
1995), and a carrier solvent for the active ingredients of insecticides and fungicides, and for
spotting fluids (WHO; Environ. Health Criteria, 1985). TCE has been replaced in the dry
cleaning industry with tetrachloroethylene (ATSDR, 1997a). Its use as a fumigant and as an
extractant for decaffeinating coffee has been discontinued in the U.S. (ATSDR, 1997a). Its use
in cosmetics and drug products was also discontinued (IARC, 1995).
1.2.3 Disposal
Generators of waste (equal to or greater than 100 kg/month) containing this contaminant
(EPA hazardous waste numbers U228, D040, and F002) must conform with U.S. EPA
regulations in storage, transportation, treatment, and disposal of waste (40 CFR 240-280, 7/1/91).
Incineration is a method of disposal, preferably after mixing with another combustible fuel. Care
must be exercised to assure complete combustion to prevent the formation of phosgene. An acid
scrubber is necessary to remove the halo acids produced. An alternative to disposal for
trichloroethylene is recovery and recycling (Sittig, 1985. Handbook Toxic Hazardous Chemicals
and Carcinogens). This compound should be susceptible to removal from wastewater by air
stripping (U.S. EPA, 1980).
1.3 POTENTIAL FOR HUMAN EXPOSURE
1.3.1 Natural Occurrence
The natural occurrence of trichloroethylene has been reported in one red microalga and in
temperate, subtropical and tropical algae (IARC, 1995).
1.3.2 Occupational Exposure
Occupational exposure to TCE of workers in industries using TCE may result from
inhalation of vapors or through dermal contact with TCE from spills.
1.3.3 Environmental
1.3.3.1 Environmental Releases
Total Toxic Release Inventory (EPA, 1996) releases for years 1987 to 1994 are shown in
Table 1-1. The receiving media are air, water, land, and for underground injection, POTW
(Public Owned Treatment Works) transfer and other transfers. These releases are reported from
manufacturing and processing facilities. Only certain facilities are required to report.
15
-------
Table 1-1. Annual Releases of Trichloroethylene in the United States (Ibs)
Year
1987
1988
1989
1990
1991
1992
1993
1994
Number of
reporting
facilities
959
951
899
807
724
681
790
783
Fugitive air
releases
25,978,879
26,168,126
22,629,351
19,030,377
17,078,485
15,585,757
14,524,316
14.788.788
Stack air
releases
29,436,952
29,759,510
27,054,328
20,900,640
18,860,997
14,866,100
15,939,964
15.083.085
Surface
water
releases
30,104
13,801
15,849
14,285
12,784
8,606
5,220
1.671
Underground
injection
18,720
390
390
805
800
466
460
288
Land
disposal
56,733
21,186
8,686
12,554
62,991
20,726
8,212
4.417
POTW
transfer
130,178
85,652
31,519
11,949
73,195
70,149
42,987
50.325
Other
transfers
11,689,590
6,509,867
4,962,054
3,879,599
10,625,967
9,807,719
10,143,591
12.307.585
Total
67,341,156
62,558,532
54,702,177
43,850,209
46,715,219
40,359,523
40,664,750
42.236.159
Source: TRI1996
Air: Most of the TCE used in the U.S. is released to the atmosphere primarily from
vapor degreasing operations by evaporation (ATSDR, 1997a). Releases to air also occur at
treatment and disposal facilities, water treatment facilities, and landfills (ATSDR, 1997a). TCE
has also been detected in stack emissions from the municipal and hazardous waste incineration
(ATSDR, 1997a). TCE has been detected in the air throughout the United States. Industrial
releases to the environment in the U.S. ranged from 55.6 million pounds in 1987 down to 29.9
million pounds in 1994 (TRI, 1996).
Water: TCE has been reported in rainwater, surface waters, groundwater, drinking
water, and seawater (IARC, 1995). TCE is released to the aquatic systems from industrial
discharges of wastewater streams (ATSDR, 1997a). It has been reported that TCE in landfill
leachate can contaminate groundwater; TCE has been reported to be one of the most frequent
contaminants of groundwater (ATSDR, 1997a).
Other Media: TCE has been reported in marine sediments, marine invertebrates, marine
mammals, foods, mother's milk, and human urine and blood (IARC, 1995) (HSDB, 1996).
1.3.3.2. Monitored Environmental Media Levels
Air: TCE has been detected in the air throughout the United States. According to ATSDR
(1997a), atmospheric levels are highest in areas concentrated with industry and population, and
lower in remote and rural regions. Air levels of TCE are highly variable (fluctuate widely over
relatively short periods of time), depending on strength of emission sources, variation of wind
direction and velocity and other meteorological factors, rain scavenging, and
photodecomposition. Levels of TCE measured in the ambient air at a variety of locations in the
U.S. are shown in Table 1-2. These data were derived from studies conducted in the late 1970's
and early 1980's.
16
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Table 1-2. Concentrations of Trichloroethylene in Ambient Air
Area
Rural
Whiteface Mountain, NY
Badger Pass, CA
Reese River, NV
Jetmar, KS
Urban and Suburban
New Jersey
New York City, NY
Los Angeles, CA
Lake Charles, LA
Phoenix, AZ
Denver, CO
St. Louis, MO
Portland, OR
Philadelphia, PA
Year
1974
1977
1977
1978
1973-79
1974
1976
1976-78
1979
1980
1980
1984
1983-84
Concentration (jig/m3)*
Mean
0.5
0.06
0.06
0.07
9.1
3.8
1.7
8.6
2.6
1.07
0.6
1.5
1.9
Range
0.3-1.9
0.005-0.09
0.005-0.09
0.04-0.11
ND-97
0.6-5.9
0.14-9.5
0.4-11.3
0.06-16.7
0.15-2.2
0.1-1.3
0.6-3.9
1.6-2.1
Source: IARC, 1995.
* 1 ug/m3=0.17ppb
Other ambient air measurement data for TCE were obtained from the Aerometric
Information Retrieval System (AIRS) using the AIRS Website: http://www.epa.gov/airsdata/.
(U.S. EPA, 1999a). These data were collected from a variety of sources including State and local
environmental agencies and cover the years 1985 to 1998. They represent about 1,200
measurements from 25 states. The most recent data (1998) come from 115 monitors located in
14 states. The 1998 air levels in |ig/m3 across all 115 monitors can be summarized as follows:
range = 0.01 to 3.9; mean = 0.88, 50th percentile = 0.32 and 90th percentile = 1.76. Table 1-3
summarizes the data by year, showing the average and number of samples. Relatively few
samples were collected in 1985 and 1986, but each year after 1986 is represented by at least 50
samples. The data suggest a general downward trend from about 1.5 |ig/m3 in the late 1980s to
0.8 |lg/m3 in the late 1990s. Table 1-4 shows the monitoring data organized by land setting
(rural, suburban, or urban) and land use (agricultural, commercial, forest, industrial, mobile, and
residential). Urban air levels are about three times higher than rural areas. Among the land use
categories, TCE levels are highest in commercial/industrial areas and lowest in forest areas.
TCE ambient air concentrations in 1990 were modeled for all census tracts of the
continental United States as part of the U.S. EPA Cumulative Exposure Project (CEP, see
www.epa.gov/cumulativeexposure/air/air.htm). (U.S. EPA, 1999b). A variety of sources were
used to obtain emissions data and the air modeling was done using a Gausian dispersion model.
Table 1-5 shows the distribution of modeled TCE ambient air concentrations across the
continental United States. The modeling suggests that 97% of the census tracts have TCE
concentrations ranging from 0 to 1.5 |ig/m3. The average level was estimated as 0.37 |ig/m3 and
the maximum as 32 |ig/m3. The averages and percentiles are better interpreted as population-
weighted values than spatial averages because all census tracts have roughly equal populations,
but are more variable in geographic area. Figure 1-1 is a map of the CEP-modeled TCE air
concentrations in New Jersey. The average across all population tracts in the state is 0.5 |ig/m3.
The map indicates, however, that the vast majority of the state, on an area basis, has levels under
17
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Table 1-3. Mean TCE Air Levels Across Monitors by Year*
Mean Concentration
(ug/m3)
n
1985
1.4
11
1986
1.39
21
1987
1.68
53
1988
4.87
57
1989
1.69
96
1990
1.84
59
1991
2.86
70
1992
1.37
76
1993
1.12
84
1994
0.95
89
1995
0.78
146
1996
0.65
150
1997
0.74
129
1998
0.88
115
Table 1-4. Mean TCE Air Levels Across Monitors by Land Setting and Use (1985 to 1998)*
Mean Concentration
(ug/m3)
n
Rural
0.42
93
Suburban
1.26
500
Urban
1.61
558
Agricultural
1.08
31
Commercial
1.84
430
Forest
0.1
17
Industrial
1.54
186
Mobile
1.5
39
Residential
0.89
450
Table 1-5. Modeled TCE Air Concentrations in Continental U.S. for 1990*
Concentration
(Hg/m3)
25th Percentile
0.13
50th Percentile
0.24
75th Percentile
0.45
95th Percentile
1.1
Maximum
32
Overall Mean
0.37
Urban Mean
0.5
*1 ppb= 5.36 |ig/m3.
-------
|~~| State Boundary, NJ
lUb (microgram/cub meter)
0.085-0.501
0.501-1.2
• •'• 1.2-3.21
3.21 - 12.025
12.025-31.584
^^V/iV':Mc"X^,'^v'^v""^'''-^^hi;"" • "•'•f'i'-v*''"'"' '••••'
Inset
Figure 1-1. Modeled TCE Levels in Air from Cumulative Exposure Project by Census Tract,
New Jersey (|lg/m3)
19
-------
0.5 jig/m3. Relatively high levels (generally 1 to 12 |ig/m3) were estimated for the densely populated
areas around Camden and Newark - Paterson. The highest levels (up to 30 |ig/m3) were estimated for
a few (presumably industrial) sectors within these areas. The CEP data suggest that this pattern (i.e.,
generally low TCE levels in rural areas, moderate levels in urban areas, and highest levels in small
commercial/industrial sectors) is common across most states. The monitoring data, as discussed earlier,
also suggest that this is the general pattern across the country.
These modeled values should be interpreted with caution. Clearly they are not as reliable as
measured values for specific locations. As discussed earlier, the AIRS data shows an average for 1990
across 59 monitoring stations of 1.84 |ig/m3. This is much higher than the national average from CEP
of 0.37 jig/m3. An important difference, though, is that the CEP estimate represents all areas of the
continental United States, whereas the 1990 AIRS data for TCE represent only 59 monitors located in
8 states. CEP compared modeled estimates with measured values in the same locations and found that
for most chemicals, agreement was usually within a factor of three, with underestimates being more
common than overestimates. More variability, however, was found in the model-monitor comparisons
for TCE than for other HAPs (hazardous air pollutants). In addition, the tendency for underestimation
in the model observed for other HAPs was not seen for TCE. The TCE model-monitor comparisons
can be summarized as follows: model-monitor comparisons were made at 57 monitoring sites, the
median of the model-monitor ratios was 0.76, arithmetic mean ratio = 2.33, geometric mean ratio =
1.02, 53% of ratios were less than 1.0, 51% were within a factor of 3 (i.e. within the range of 0.33 to
3.0), 19% were less than 0.33 and 30% were greater than 3.0.
Water: According to IARC (1995), the reported median concentrations of TCE in 1983-84
were 0.5 |ig/l in industrial effluents and 0.1 |ig/l in ambient water. ATSDR (1997a) has reported that
TCE is the most frequently reported organic contaminant in groundwater and the one present in the
highest concentration in a summary of ground water analyses reported in 1982. It has been estimated
that between 9 percent and 34 percent of the drinking water supply sources tested in the U.S. may
have some trichloroethylene contamination. This estimate is based on available Federal and State
surveys (ATSDR, 1997a). Results from an analysis of the EPA STORET Data Base (1980-1982)
showed that TCE was detected in 28 percent of 9,295 surface water reporting stations nationwide
(ATSDR, 1997a). Levels of TCE found in rainwater, groundwater, and drinking water are shown in
Table 1-6.
More recently, the U.S. EPA Office of Ground Water and Drinking Water reported that most
water supplies are in compliance with the maximum contaminant level [maximum contaminant level
(MCL), 5 |ig/L] and that only 407 samples out of many thousands taken from community and other
water supplies throughout the country over the past 11 years (1987-1997) have exceeded the MCL
limit for TCE (U.S. EPA, 1998).
TCE concentrations in ground water have been measured extensively in California. The data
were derived from a survey of large water utilities (i.e., utilities with more than 200 service
connections). The survey was conducted by the California Department of Health Services (DHS,
1986). From January 1984 through December 1985, wells in 819 water systems were sampled for
organic chemical contamination. The water systems use a total of 5,550 wells, 2,947 of which were
sampled. TCE was found in 187 wells at concentrations up to 440 |ig/L, with a median
20
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Table 1-6. Concentrations of Trichloroethylene in Water
Water Type
Industrial
Effluent
Surface Waters
Rainwater
Groundwater
Drinking water
Location
U.S.
U.S.
Portland, OR
MN
NJ
NY
PA
MA
AZ
U.S.
U.S
U.S.
MA
NJ
CA
CA
NC
ND
Year
83
83
84
83
76
80
80
76
76
77
78
84
84-
85
84
84
84
Mean
0.006
23.4
66
5
5
Median
0.5
0.1
Range
0.002-0.02
0.2-144
<1530
<3800
<27300
<900
8.9-29
0.2 - 49
0-53
0.5-210
max. 267
max. 67
8-12
Number of Samples
NR
NR
NR
NR
NR
NR
NR
NR
NR
1130
486
486
48
48
Ref.
IARC, 1995
IARC, 1995
Ligocki, et.al , 1985
Sabel, et.al, 1984
Burmaster, et. al. '82
Burmaster, et. al. '82
Burmaster, et. al. '82
Burmaster, et. al. '82
IARC, 1995
IARC, 1995
IARC, 1995
IARC, 1995
IARC, 1995
Cohn, et.al., 1994
EPA, 1987
EPA, 1987
EPA, 1987
EPA, 1987
NR - Not Reported
concentration of 3.0 |ig/L. Generally, the most contaminated wells and the wells with the highest
concentrations were found in the heavily urbanized areas of the state. Los Angeles County
registered the greatest number of contaminated wells (149).
Other Media: Levels of TCE were found in the sediment and marine animal tissue
collected in 1980-81 near the discharge zone of a Los Angeles County waste treatment plant.
Concentrations were 17 |ig/l in the effluent, <0.5 |ig/kg in dry weight in sediment, and 0.3-7
jig/kg wet weight in various marine animal tissue (IARC, 1995). TCE has also been found in
foods in the U. S. and the United Kingdom. The average concentrations of TCE in food in the
U.S. were the following (IARC, 1995):
0.9 |ig/kg in grain-based foods;
1.8 |ig/kg in table-ready foods;
73.6 |ig/kg in butter and margarine;
0.5 |ig/kg in peanut butter;
3.0 |ig/kg in ready-to-eat cereals;
1.3 |ig/kg in highly processed foods; and
3.8 |ig/kg in cheese products.
Biological Monitoring: Biological monitoring studies have detected TCE in human
blood and urine in the U.S. and other countries such as Croatia, China, Switzerland, and
Germany (IARC, 1995). Concentrations of TCE in persons exposed through occupational
degreasing operations were most likely to have detectable levels (IARC, 1995). In 1982, eight of
21
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eight human breastmilk samples from four U.S. urban areas had detectable levels of TCE. The
levels of TCE detected, however, were not specified (HSDB, 1996; ATSDR, 1997a).
The Third National Health and Nutrition Examination Survey (NHANES HI) examined
TCE concentrations in blood in 677 non-occupationally exposed individuals drawn from the
general U.S. population who were selected on the basis of age, race, gender and region of
residence (IARC, 1995 and Ashley et al., 1994). The samples were collected during 1988 to
1994. TCE levels in whole blood were below the detection limit of 0.01 |ig/l for about 90% of
the people sampled (Table 1-7). Assuming that nondetects equal half of the detection limit, the
mean concentration was about 0.017 jig/I.
1.3.3.3 Environmental Fate and Transport
1.3.3.3.1 Summary
The summary is based on the data presented in the subsequent fate and transport
subsections.
Fate in Terrestrial Environments: The dominant fate of trichloroethylene released to
surface soils is volatilization. Because of its moderate to high mobility in soils, trichloroethylene
introduced into soil (e.g., landfills) has the potential to migrate through the soil into groundwater.
The relatively frequent detection of trichloroethylene in groundwater confirms the mobility of
trichloroethylene. Biodegradation in soil and groundwater may occur at a relatively slow rate
(half-lives on the order of months to years) (Howard et al., 1991).
Fate in the Atmosphere: In the atmosphere, trichloroethylene is expected to be present
primarily in the vapor phase rather than sorbed to particulates because of its high vapor pressure.
Some removal by scavenging during wet precipitation is expected because of the moderate
solubility of trichloroethylene in water (1.1 g/L). The major degradation process affecting vapor
phase trichloroethylene is photo-oxidation by hydroxyl radicals (half-life on the order of 1 to 11
days) (HSDB, 1996).
Fate in Aquatic Environments: The dominant fate of trichloroethylene released to
surface waters is volatilization (predicted half-life of minutes to hours). Bioconcentration,
biodegradation, and sorption to sediments and suspended solids are not thought to be significant
(HSDB, 1996).
Table 1-7. TCE Levels in Whole Blood by Population Percentile*
Percentiles
Concentration
(ng/i)
10
0.005
20
0.005
30
0.005
40,
0.005
50
0.005
60
0.005
70
0.005
80
0.005
90
0.012
* Nondetects assumed equal to half the detection limit (0.01 (-lg/L).
Data from IARC (IARC, 1995) and Ashley (Ashley, 1994)
22
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1.3.3.3.2 Transport and Partitioning
Soil Adsorption/Mobility: Kocs ranging from 30 to 150 have reported in studies with
various soil types indicate that trichloroethylene should exhibit moderate to high mobility in soil.
The mobility of trichloroethylene in soil has been confirmed in soil column studies and river
bank infiltration studies (HSDB, 1996).
Volatilization: The dominant removal mechanism for trichloroethylene in surface waters
is volatilization. The half-life will depend on wind and mixing conditions and is estimated to
range from several minutes to hours in rivers, lakes, and ponds based on laboratory experiments
and field studies. Because of its high vapor pressure (73 torr at 25 degrees C) and relatively low
soil adsorption coefficient (30 to 150), trichloroethylene is expected to volatilize from soil
surfaces and also from suspended particulate matter in the atmosphere (HSDB, 1996).
Bioconcentration: Bioconcentration factors of 17 to 39 have been reported in bluegill
sunfish and rainbow trout. Marine monitoring data suggest BCFs of 2 to 25. Therefore,
bioconcentration in aquatic organisms should not be significant and there is little potential for
biomagnification in the food chain (HSDB, 1996).
1.3.3.3.3 Transformation and Degradation Processes
Biodegradation: Based on limited acclimated soil screening test data, trichloroethylene
undergoes aerobic biodegradation at a very slow rate with a half-life estimated at 6 months to a
year. Slow degradation under anaerobic conditions is expected (half-life of months to years)
based on the results of limited anaerobic sediment studies (Howard et al., 1991).
Photodegradation: Photolysis in the atmosphere or in aquatic environments is expected
to proceed very slowly, if at all. Trichloroethylene does not absorb UV light at wavelengths of
less than 290 nm and thus will not directly photolyze. Based on measured rate data for the vapor
phase photo-oxidation reaction with hydroxyl radicals, the estimated half-life of trichloroethylene
in the atmosphere is on the order of 1 to 11 days with production of phosgene, dichloroacetyl
chloride, and formyl chloride. Under smog conditions, degradation is more rapid (half-life on the
order of hours) (HSDB, 1996; Howard et al., 1991).
Hydrolysis: Trichloroethylene is not hydrolyzed under normal environmental conditions.
However, slow photo-oxidation in water (half-life of 10.7 months) has been reported (HSDB,
1996; Howard etal., 1991)
1.4 HUMAN EXPOSURE AND POPULATION ESTIMATES
1.4.1 General U.S. Population
Because of the pervasiveness of TCE in the environment, most people are exposed to it
through ingestion of drinking water, inhalation of ambient air, or ingestion of food (ATSDR,
1995a). Contamination of drinking water with TCE varies according to location and with the
drinking water source (whether source is surface water or groundwater). TCE readily volatilizes
from water and inhalation of indoor air may be a major route of exposure in homes with
23
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contaminated water supply (ATSDR, 1997a). Available data indicate that for most people,
dermal exposure is not an important route of exposure (ATSDR, 1997a).
The 1998 AIRS monitoring data indicate a mean outdoor air level of 0.88 |lg/m3. Using
this value and an inhalation rate of 20 m3 air/day yields an exposure estimate of 18 |ig/day. This
is consistent with ATSDR (ATSDR, 1997a), which reported an average daily air intake for the
general population of 11 to 33 |lg/day The California survey of large water utilities in 1984
found a median concentration of 3.0 |lg/L (DHS, 1986). Using this value and a 2 L/day water
consumption rate yields an estimate of 6 |lg/day. This is consistent with ATSDR (ATSDR,
1997a) which reported an average daily water intake for the general population of 2 to 20 |ig/day.
The use of ambient air data to estimate inhalation exposure does not account for possible
differences between contaminant levels in indoor vs. outdoor air. TCE readily volatilizes from
water and indoor inhalation exposure may be comparable or greater than ingestion exposures in
homes where the water supply contains TCE (ATSDR, 1997a, Andelman, et.al., 1985, Giardino,
et.al., 1992, Andelman, et.al., 1986a, Andelman, et.al., 1986b). For example, in two homes using
well water with TCE levels averaging 22 to 128 |ig/L, the TCE levels in bathroom air ranged
from <0.5 to 40 mg/m3 when the shower was run less than 30 minutes (Andelman et al., 1985).
In one study, the transfer of TCE from shower water to air had a mean efficiency of 61%
(independent of water temperature); it was concluded that a 10-minute shower in TCE-
contaminated water could result in a daily inhalation exposure comparable to that expected from
drinking TCE-contaminated tap water (ATSDR, 1997a). Indoor use of TCE containing products
can also contribute to exposures. Wallace et al. (Wallace, et.al., 1985) concluded that indoor air
contributes more to overall TCE exposure than outdoor air. This was based on monitoring of
expired breath of 190 people in New Jersey. This is also indicated in the TEAM (Total
Exposure Assessment Methodology) Study (U.S. EPA, 1987), which shows, for example, that
the ratio of the indoor to outdoor TCE concentration for Greensboro, NC was about 5:1.
Accordingly, ambient air-based exposure estimates probably under represent total inhalation
exposures.
TCE in bathing water can also cause dermal exposure. A modeling study has suggested
that a significant fraction of the total dose associated with exposure to volatile organics in
drinking water results from dermal absorption (Brown, et.al., 1984).
Pharmacokinetic modeling can be used to gain further understanding of general
population exposure. Clewell et al. (Clewell, et.al., 1995) developed a physiologically based
pharmacokinetic model for TCE that can be used to estimate the long-term average inhaled air
concentration that would result in a measured blood concentration, assuming no other TCE
exposure. The model can also estimate the long-term average ingested dose that would result in
a measured blood concentration, assuming no other TCE exposure. This dose can be converted
to a TCE water concentration assuming an ingestion rate such as 2 L/day. For each of these
exposure scenarios, the model also provides the corresponding concentrations of trichloroacetic
acid (TCA) and dichloroacetic acid (DCA) in blood and the amount of TCE metabolized per day.
This model was applied to the range of TCE levels in blood as measured in NHANES in. Table
1-8 shows the resulting exposure estimates corresponding to the range of TCE blood levels. The
TCE environmental concentrations modeled from blood levels exceeded the range of measured
values for air and water: modeled mean concentration in drinking water was 59.5 |lg/L
(measured range was trace to 50 |ig/L) and the modeled mean air concentration was 4.2 |ig/m3
24
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(measured range was for 0.01 to 3.9 |lg/m3) . This implies that neither inhalation nor water
ingestion dominate exposure; rather both contribute to the total exposure. Exposure estimates
derived from blood cannot distinguish among exposure routes and sources. It is generally
believed that TCE exposure occurs primarily via water consumption and air inhalation, but it is
impossible to use the blood data to directly estimate how much of the total exposure is
attributable to each. A wide range of combinations of exposures from air and water could have
produced the measured blood levels. As noted earlier, most water supplies have TCE levels
under the MCL of 5 |ig/L. The modeling suggests that exposure at the MCL would correspond
to a very low blood level. This implies that the TCE exposure via the air and other nonwater
pathways may generally be more important than water ingestion. Table 1-8 provides the
modeled exposure estimates corresponding to a range of blood levels, and Table 1-9 shows a
comparison of measured and modeled TCE concentrations in air and drinking water.
1.4.1.1 Extent of General Population Exposure
Because of the pervasiveness of TCE in the environment, most people are likely to have
some exposure via one or more of the following pathways: ingestion of drinking water,
inhalation of ambient air, or ingestion of food (ATSDR, 1995a). As noted earlier, the NHANES
survey suggests that about 10% of the population has detectable levels of TCE in blood. The
exposures in these individuals may be higher than those in others in the general population as a
result of a number of factors. As discussed below, some occupations and the use of certain
consumer products can cause increased TCE exposure via inhalation. In addition, some members
of the general population may have increased TCE exposure via their drinking water. The extent
of TCE exposure via drinking water is difficult to estimate, but the following discussion provide
some perspective on this issue.
Table 1-8. Modeled Exposure Estimates for TCE
10th percentile blood level
(0.005 |ig/L)
90th percentile blood level
(0.012 jig/L)
Mean blood level (0.0 17
US/L)
Air concentration
(|ig/m3)
1.25
3.0
4.3
Ingested dose
(^ig/kg-day)
0.5
1.2
1.7
Water concentration
(Hg/L)
17.5
42.0
59.5
Table 1-9. Comparison of Measured and Modeled TCE Concentrations
Air
Drinking Water
Measured Range
0.0005 to 16ug/m3
trace to 50 |ig/L
Modeled Mean
4.58 |Jg/m3
59.5 |ig/l
25
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TCE is the most frequently reported organic contaminant in ground water (ATSDR,
1997a), 93% of the public water systems in the United States obtain water from groundwater
(U.S. EPA, 1995) and between 9% and 34% of the drinking water supply sources tested in the
United States may have some TCE contamination (ATSDR, 1997a). Although commonly
detected in water supplies, the levels are generally low since, as discussed earlier, MCL
violations for TCE in public water supplies are relatively rare for any extended period (U.S. EPA,
1998). Private wells, however, are often not closely monitored and if located near TCE
disposal/contamination sites where leaching occurs, may have undetected contamination levels.
About 10% of Americans (27 million people) obtain water from sources other than public water
systems, primarily private wells (U.S. EPA, 1995). TCE is a common contaminant at Superfund
sites. It has been identified in at least 861 sites of the 1,428 hazardous waste sites proposed for
inclusion on the EPA National Priorities List (NPL) (See Figure 1-2. ATSDR, 1997a). Studies
have shown that many people live near these sites: 41 million people live less than 4 miles from
one or more of the nation's NPL sites, and on average 3,325 people live within 1 mile of any
given NPL site (ATSDR, 1996b). Thus, although exact estimates cannot be made, many people
are probably exposed to TCE via drinking water from private wells. It is not known how often
such exposures would be above the MCL.
Some members of the general population may have elevated TCE exposures. ATSDR
(ATSDR, 1997a) has reported that TCE exposures may be elevated for people living near waste
facilities where TCE may be released, residents of some urban or industrialized areas, people
exposed at work (discussed further below) and individuals using certain products (also discussed
further below). Because TCE has been detected in breast milk samples of the general population,
infants who ingest breast milk may be exposed. Also, since TCE can be present in soil, children
may be exposed through activities such as playing in or ingesting soil.
1.4.2 Occupational Exposure
Occupational exposure to TCE in the U.S. has been identified in various degreasing
operations, silk screening, taxidermy, and electronic cleaning (IARC, 1995). The major use of
trichloroethylene is for metal cleaning or degreasing (IARC, 1995). Degreasing is used to
remove oils, greases, waxes, tars, and moisture before galvanizing, electroplating, painting,
anodizing, and coating. The five primary industrial groups are: furniture and fixtures; electronic
and electric equipment; transport equipment; fabricated metal products; and miscellaneous
manufacturing industries (IARC, 1995). Additionally, TCE is used in the manufacture of
plastics, appliances, jewelry, plumbing fixtures, automobile, textiles, paper, and glass (IARC,
1995). NIOSH conducted a survey of various industries from 1981 to 1983 and estimated that
approximately 401,000 U.S. employees in 23,225 plants in the U.S. are potentially exposed to
TCE (IARC, 1995; ATSDR, 1997a). The majority of published worker exposure data are for
degreasing operations; time weighted average (TWA) concentrations from personal monitoring
ranged from 6,535-27,775 |ig/m3 (1.2 to 5.1 ppm) at individual industrial sites where TCE was
used (ATSDR, 1997a).
According to ATSDR (1997a), workers, especially in the vapor degreasing industry, are
exposed to the highest levels of TCE through inhalation. These workers may be exposed to
26
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levels ranging from approximately 5,446-544,600 |ig/m3 (1 to 100 ppm), based on monitoring
survey (ATSDR, 1997a).
1.4.3 Consumer Exposure
Consumer products reported to contain TCE include wood stains, varnishes, and finishes;
lubricants; adhesives; typewriter correction fluids; paint removers; and cleaners (ATSDR,
1997a). Use of TCE has been discontinued in some consumer products (i.e., as an inhalation
anesthetic, fumigant, and an extractant for decaffeinating coffee) (ATSDR, 1997a).
1.5 CHAPTER SUMMARY
Table 1-10 summarizes the findings of TCE.
27
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FREQUENCY
1 TO 15 SITES
57 TO 72 SITES
|llllll| 16 TO 33 SITES
S3 TO 32 SITES
Figure 1-2. Frequency of NPL Sites with Trichloroethylene Contamination (Source: ATSDR,
1997a)
28
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Table 1-10. Trichloroethylene Summary
Uses
Production
Releases
Properties/Fate
Media Levels
General Population
Exposure
Special Population
Exposures
Estimates
Metal cleaning and degreasing; many other
solvent applications
1.45xl08kg/yr
All media - 42 million Ib/yr (mostly to ai) in
1994
Volatile, water soluble, stable in air, no
significant bio-degradation or bio-
concentration
- Air: mean = 0.88 [ig/m3
- Drinking water: 2-7 |-ig/L
- Groundwater: median = 3 |-ig/L
- Human blood: mean = 0.017 |-ig/L
- Some data on food, human milk, and
other tissues
- Inhalation: 11-33 [ig/d (urban)
- Water ingestion: 2-20 |ig/d
- Food exposure possible but probably low
- Nursing infants
- Workers in production plants or
degreasing operations: 1-100 ppm
Support
Well documented in numerous studies,
recent information
1991 data
TRI (U.S. EPA, 1996) is primary source, so
current but uncertain due to self reporting
and exemptions
Well documented in numerous studies,
recent information
- Air data is from 1 998 survey of 1 1 5
monitors in 14 states
- Based on extensive data from public
water systems which routinely monitor
for TCE, private systems generally do not
monitor for TCE and levels not well
established
- Groundwater estimate from 1985 survey
of 819 water systems in CA
- Blood data collected from 1 988 to 1 994
from 677 individuals
- n's and dates for other data unclear, but
appear very limited
- Inhalation and ingestion estimates based
on very limited monitoring data (see
above)
- Insufficient food data for reliable
estimates of exposure
- Human milk data insufficient for
estimating exposure
- Worker data based on several recent
surveys
29
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2.0 TETRACHLOROETHYLENE (PERCHLOROETHYLENE)
2.1 CHEMICAL AND PHYSICAL PROPERTIES
The information/data presented in this section and the supporting references were
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).
2.1.1 Nomenclature
CAS No.: 127-18-4
Synonyms: 1,1,2,2-tetrachloroethylene; ethene, tetrachloro-,
perchloroethylene; tetrachloroethene; PCE.
Trade Names: ENT 1; 860; Perclene; Persec; Antisal 1; Dow-Per; Perchlor; Perklone.
2.1.2 Formula and Molecular Weight
Molecular Formula: C2C14
Molecular Weight: 165.83
2.1.3 Chemical and Physical Properties
Description: Colorless liquid, ether-like or chloroform-like odor (Merck Index, 10th
Ed., 1983).
Boiling Point: 121° C @ 760 mm Hg (Weast. Hdbk. Chem. & Phys., 68th Ed., 1987-88).
Melting Point: -19° C (Weast. Hdbk. Chem. & Phys., 68th Ed., 1987-88).
Density: 1.6227 at 20° C/4° C (Weast. Hdbk. Chem. & Phys., 68th Ed.,
1987-88).
Spectroscopy
Data: Sadtler Ref. Number: 237 (IR, prism); 79 (IR, grating) (Weast.
Hdbk.Chem. & Phys., 60th Ed., 1979). Index of refraction: 1.5053
@ 20° C/D (Weast. Hdbk. Chem. & Phys., 68th Ed., 1987-88). IR:
4786 (Coblentz Society Spectral Collection), Mass: 1053 (Atlas of
Mass Spectral Collection)
Solubility: Soluble in water, 0.15 g/100 ml @ 25°C (IARC Monographs)
(1972-present) 1979. Miscible with alcohol, ether, chloroform,
benzene (Merck Index, 10th Ed., 1983).
Volatility: Vapor Pressure - 18.47 mm Hg at 25°C (Riddick, J.A., et al. (1986)
Organic Solvents: Physical Properties and Methods of Purification).
30
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Vapor Density - 5.7 (air = 1) (Browning Tox. & Metab. Indus. Solv.,
1965).
Stability: Rapidly deteriorates in warm climates (Goodman, 1975);
tetrachloroethylene is stable up to 500°C in the absence of catalysts,
moisture, and oxygen (WHO, Environ. Health Criteria, 1984).
Reactivity: Reacts with metals to form explosive mixtures; sodium hydroxide,
possible explosion (ITU Tox. & Hazard Indus. Chem. Safety Manual,
1982). Incompatible with chemically active metals, such as barium,
lithium, and beryllium (NIOSH Pocket Guide, 1985).
Octanol/Water
Partition
Coefficient: log Kow = 3.40 (Hansch C., Leo A.J., 1985, Medchem Project Issue
No. 26)
2.1.4 Technical Products and Impurities
Tetrachloroethylene is available in the USA in the following grades: purified, technical,
USP, spectrophotometric, and dry-cleaning. The technical and dry-cleaning grades both meet
specifications for technical grade and differ only in the amount of stabilizer added to prevent
decomposition. Stabilizers include amines or mixtures of epoxides and esters. Typical analysis
of the commercial grade is nonvolatile residue, 0.0003%; free chlorine, none; moisture, no cloud
at -5°C. USP grade contains not less than 99.0% and no more than 99.5% tetrachloroethylene,
the remainder consisting of ethanol (IARC Monographs, 1972-Present V20 492, 1979). PCE is
also available in the United States in veterinary preparation (Nema Worm Capsules) (AMA Drug
Eval., 1986).
2.2 PRODUCTION AND USE
The information/data presented in this section and the supporting references were
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).
2.2.1 Production
U.S. Production: (1985) 3.08 x 1011 g; (1986) 1.84 x 1011 g; (1989) 2.14 x 1011 g;
(1990) 1.6 x 1011 g; (1991) 1.08 x 1011 g; (1992) 1.12 x 1011 g; (1993) 1.23 x
1011 g (ATSDR, 1995b; HSDB, 1996).
Import volumes: (1982) 1.70x 1010 g; (1985) 6.36 x 1010 g; (1986) 8.3 x 107g
(Bureau of the Census, U.S. Imports for Consumption and General Imports, 1985;
1986).
Export volumes: (1983) 2.47 x 1010 g (SRI); (1985) 9.84 x 109 g (Bureau of the
Census, U.S. Exports, 1985).
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2.2.2 Uses
The three major uses of tetrachloroethylene in the U.S. are textile dry-cleaning;
processing and finishing in both cold cleaning and vapor degreasing of metals; and as a chemical
intermediate in the synthesis of fluorocarbon 113, 114, 115, and 116. However, because of an
international agreement to protect against ozone layer depletion, this latter use is being phased
out (IARC, 1995). Additionally, PCE is used as a heat-exchange fluid; a scouring, sizing, and
desizing agent; a carrier solvent for fabric dyes and finishes; a water repellant in textile
manufacture; a component of aerosol laundry-treatment products; a solvent for silicones;
insulating fluid and cooling gas in electric transformers (SRI); and a solvent in typewriter
correction fluids (IARC, 1995). Other reported uses are extractant in the pharmaceutical
industry; a pesticide; and a solvent for adhesive formulations, printing inks, leather treatments;
and paper coatings. It has also been reported to be used as an anthelminthic in the treatment of
hookworm and some trematode infestations (IARC, 1995) although it has been replaced now
with other less toxic and easier-to-administer compounds.
The current end-use pattern for PCE is estimated to be 55% for chemical intermediates,
25% for metal cleaning and vapor degreasing, 15% for dry cleaning and textile processing, and
5% for other unspecified uses (ATSDR, 1997b).
2.2.3 Disposal
Incineration at a temperature greater than 450°C is a method of disposal, preferably after
mixing with another combustible fuel. Care must be exercised to assure complete combustion to
prevent the formation of phosgene. An acid scrubber is necessary to remove the halo acids that
are produced (ATSDR, 1997b). PCE may be disposed of in landfills by adsorbing it in
vermiculite, dry sand, earth, or a similar material and disposing in a secured sanitary landfill
(ATSDR, 1997b). According to HSDB (1996), an environmental regulatory agency should be
consulted prior to implementing land disposal of waste containing PCE. The HSDB database
presents numerous disposal practice precautions for carcinogens from the IARC 1979 Scientific
Publication No. 33.
2.3 POTENTIAL FOR HUMAN EXPOSURE
2.3.1 Natural Occurrence
The natural production of PCE in temperate, subtropical, and tropical algae, and in one
red microalga has been reported (IARC, 1995).
2.3.2 Occupational
There is considerable potential for exposure to PCE (dermal and inhalation) during its use
in degreasing and dry cleaning operations (IARC, 1995). Other occupational areas where
exposures may occur are urethane foam, automotive brake, and rubber molding manufacture;
motion picture film processing; taxidermy; electroplating; and graphic arts.
32
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2.3.3 Environmental
PCE is released to the environment through industrial emissions, from building products
and consumer products. Releases are primarily to the atmosphere, but there are additional
releases to surface water and land in sewage sludges, other liquids, and solid wastes. Because of
the high vapor pressure, PCE is volatilized to the atmosphere from these sources (ATSDR,
1997b). The Toxic Release Inventory (TRI) industrial release data for PCE releases to air, water,
land, and other media from manufacturing facilities are presented in Table 2-1. The number of
reporting facilities and the total releases per year are also shown in Table 2-1.
2.3.3.1 Environmental Releases
Air: Levels of PCE in air have been reported in numerous studies, both in the U.S. and
worldwide. PCE has been found in ambient air, especially in the near vicinity of dry cleaning
operations. The TRI emission estimate for total PCE industrial emissions to the atmosphere was
32.9 million pounds in 1987; 17 million pounds in 1991; and 5.2 million pounds in 1994 (TRI,
1996).
Water: PCE has been detected in rainwater, surface water, drinking water, and seawater.
According to TRI, releases to surface water totaled 161,000 pounds in 1987; 7,448 pounds in
1991; and down to 3,872 pounds in 1994 (TRI, 1996).
Other Media: Levels of PCE have been reported in foods, marine invertebrates, fish,
waterbirds, marine mammals, marine sediments, and human blood, urine, breast milk, and tissue
(IARC, 1995; ATSDR, 1997b; HSDB 1996). TRI estimates of releases for land disposal were
618,026 pounds in 1993 down to 4,349 pounds in 1994 (TRI, 1996).
Table 2-1. Releases of Tetrachloroethylene (Ibs)
Year
1987
1988
1989
1990
1991
1992
1993
1994
Number of
Reporting
Facilities
715
746
732
666
577
518
490
459
Fugitive Air
Releases
15,628,341
16,336,282
12,187,707
9,351,150
6,669,093
5,305,402
4,538,411
4,671,751
Stack Air
Releases
17,273,459
19,786,265
15,753,023
13,597,042
10,339,157
7,389,816
6,634,275
5,530,378
Surface
Water
Release
160,921
33,314
53,940
21,510
7,448
10,317
10,152
3,872
Underground
Injection
354,000
72,250
50,000
11,012
14,000
12,780
15,041
4,051
Land
Disposal
5,220
82,144
10,791
1,260
23,309
9,354
618,026
4,349
POTW
Transfer
468,295
558,691
467,181
450,922
234,642
111,517
111,002
62,053
Other Transfers
9,155,484
5,582,693
4,356,193
4,548,481
16,290,418
11,011,874
9,564,687
10,411,056
Total
43,046,435
42,452,385
32,879,567
27,982,043
33,578,644
23,851,578
21,492,084
20,687,969
Source: TRI, 1996.
33
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2.3.3.2 Monitored Environmental Media Levels
Air: Measured levels of PCE in air in rural, urban, and suburban locations in the U.S. are
shown in Table 2-2.
Water: Measurements of PCE in surface waters, groundwater, and drinking water in
U.S. locations are shown in Table 2-3.
Other Media: PCE was reported as a contaminant of cosmetic products (0.3-400 |ig/l)
and cough mixtures (0.2-97.1 jig/1) (IARC, 1995). PCE has been detected in blood and urine of
occupationally exposed persons. It has also been reported in 7 of 42 breast milk samples from
the general population in 4 urban areas of the U.S. (IARC, 1995; HSDB, 1996). PCE was
detected at 1.4 - 5.7 ppt in rain/snow in California (HSDB, 1996). Levels found in food included
(ATSDR, 1997b; HSDB, 1996):
Crab apple jelly - 2.5 ng/kg
Grape jelly - 1.6 |ig/kg
Dairy products - 0.3 - 13 |ig/kg
Oils and fats - 0.01 - 7 |ig/kg
Beverages (canned fruit drinks, instant coffee, tea) - 2 - 3 |ig/kg
Fruits and vegetables (potatoes, apples, pears, tomatoes) - 0.7 - 2 |ig/kg
Grain-based products (wheat, corn, oats, corn grits, corn meal) - 1.8 - 2.5 |ig/kg
Table 2-2. Concentrations of Tetrachloroethylene in Ambient Air
Area
Rural
Southern Washington, USA
Rural California, USA
Central Michigan, USA
USA, 577 sites
Urban and Suburban
New York City, NY, USA
Houston, TX, USA
Detroit, MI, USA
Los Angeles, CA, USA
Phoenix, AZ, USA
Oakland, CA, USA
San Diego, CA, USA
San Francisco, CA, USA
Sacramento, CA, USA
Concentration (ng/m3)*
Mean
136
210
1,085
9,017
2,644
3,119
10,034
6,739
2,054
1,831
1,559
475
Range
200-300
1,085-71,936
<678-30,510
678-14,916
1,180-14,001
875-25,066
359-9,831
Source: IARC, 1995.
1 ng/m3=0.00014 ppb
34
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Table 2-3. Concentrations of Tetrachloroethylene in Water
Area
Surface Waters:
Seawater
Eastern Pacific
North Atlantic
Rainwater
Los Angels, CA, 1982
La Jolla, CA
Portland, OR
Germany
Rivers
USA, five states, surface water (14% of samples
positive)
Drinking Water
New Jersey, USA, 1981-83
New Jersey, USA
Woburn, MA, USA
Groundwater:
USA, CA, 945 Water supplies
USA, five sites, 28% of samples positive
Concentration (ng/L)
Mean
0.021
0.006
0.08
0.4
7.7
Range
0.0001-0.0021
0.00012-0.0008
0.0008-0.009
max. 21
max. 14
66-212
max. 0.58-69
max. 1500
Source: IARC, 1995.
Levels of PCE detected in margarine from several supermarkets in the Washington, D.C.,
area were >50 ppm in 10.7 percent of the products sampled. The highest levels, ranging from
500 to 5,000 ppb, were found in samples from a store located near a dry cleaning operation
(ATSDR, 1995b). The concentrations were highest on the ends of the margarine stick and
decreased towards the middle, suggesting that contamination occurred after manufacturing rather
than during the manufacturing process (ATSDR, 1997b).
Biological Monitoring: The Third National Health and Nutrition Examination Survey
(NHANES HI) examined perchloroethylene concentrations in blood in 590 non-occupationally
exposed individuals (IARC, 1995 and Ashley et al., 1994). This study involved persons in the
general U.S. population who were selected on the basis of age, race, gender and region of
residence. The samples were collected during 1988 to 1994. As shown in Table 2-4 below, the
tetrachloroethylene levels in whole blood span over a wide range with a mean concentration of
0.19 |ig/l. This result is also shown on Figure 2-1.
35
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0.4
0.3
c
1 0.2
c
I
8 0.1
JHBBMLJIHIMLjJMHBHLjJHMMML^JHHMMLjJi^^
0
10 20 30 40 50 60 70 80 90
Population Percentile
Source: NHANES 111 (Ashley, D., 1997, CDC). N=590
Figure 2-1. Concentration of Tetrachloroethylene in Blood at Selected Population Percentiles
36
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Table 2-4. Tetrachloroethylene Levels in Whole Blood by Population Percentile*
Percentiles
Concentration (|-ig/l)
10
0.015
20
0.015
30
0.035
40
0.049
50
0.063
60
0.086
70
0.120
80
0.180
90
0.35
* detection limit = 0.03 [ig/L
Source: Personal communication from David Ashley, Center for Disease Control.
Clewell (personal communication to J. Schaum, 1997) applied the NHANES in blood
data for tetrachloroethylene to a physiologically based pharmacokinetic model (described in
Gearhart et al., 1993) to estimate the following quantities:
• The long term average inhaled air concentration which would result in the
measured blood concentration, assuming no other perchloroethylene exposure.
• The long term average ingested dose which would result in the measured blood
concentration, assuming no other perchloroethylene exposure. This dose was
converted to a perchloroethylene water concentration assuming an ingestion rate
of 2 I/day.
• For each of these exposure scenarios, the model also provides the corresponding
concentrations of TCA and DCA in blood and the amount of perchloroethylene
metabolized per day.
This model (Gearhart et al., 1993) includes 30 to 40 parameters in its structure. Typically
only 25 to 30 percent of these parameters have a significant enough impact on the model
prediction to be considered. Significant parameters in this model include parameters such as
blood/air and tissue/blood partition coefficients, organ volumes, body weight, ventilation rates,
and in vivo metabolic rates.
Table 2-5 below provides the modeled exposure estimates corresponding to a range of
blood levels.
As shown in Table 2-6 below, the modeled mean perchloroethylene concentrations fall
within the range of measured values for both air and water.
Further interpretations of this analysis are discussed below:
• The monitoring data are much older than the blood data (collection dates: air
1975-1981, water 1973-1994 and blood 1988 - 1994). Thus, the exposure
estimates derived from blood should better reflect current conditions.
• Environmental monitoring data (especially for air) may not be very representative
of actual exposures. For example, ambient air monitors are fixed units typically
located on top of buildings and do not sample the air that a person actually
37
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Table 2-5. Modeled Exposure Estimates for Tetrachloroethylene
Blood Level
lOthpercentile (0.015 |ig/l)
90thpercentile(0.35|^g/l)
Mean (0.1 9 |ig/l)
Air Concentration
(Hg/m3)
1.34
31.2
17.0
Ingested Dose
(|ig/kg-day)
0.24
5.5
3
Water Concentration
(Hg/1)
8.4
192.5
105
Table 2-6. Comparison of Measured and Modeled Perchloroethylene Concentrations
Air
Water
Measured Range
0.2 to 30 |Jg/m3
0.0001 to 210 |ig/l
Modeled Mean
18.5 Lig/m3
105 |ig/l
breathes throughout a day. Also, indoor air (which is not measured by ambient air
monitors) may be a more important contributor to perchloroethylene exposure
than outdoor air. In contrast, blood measurements reflect the actual exposure that
an individual experiences. Thus, the exposure estimates derived from blood
should more accurately reflect total exposure.
Exposure estimates derived from blood cannot distinguish between exposure
routes and sources. It is generally believed that perchloroethylene exposure
occurs primarily via water consumption and air inhalation, but it is impossible to
use the blood data to estimate how much of the total exposure is attributable to
each. A wide range of combinations of exposures from air and water could have
produced the measured blood levels.
2.3.3.3 Environmental Fate and Transport
2.3.3.3.1 Summary
The summary is based on the data presented in the subsequent fate and transport
subsections.
Fate in Terrestrial Environments: The dominant fate of tetrachloroethylene released to
surface soils is volatilization. Because of its low to moderate mobility in soils,
tetrachloroethylene introduced into soil (e.g., landfills) has the potential to migrate through the
soil into groundwater. Biodegradation under anaerobic conditions in soil and groundwater may
occur at a relatively slow rate (half-lives on the order of months or longer (HSDB, 1996).
38
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Fate in the Atmosphere: In the atmosphere, tetrachloroethylene is expected to be present
primarily in the vapor phase rather than sorbed to particulates because of its high vapor pressure.
Removal by scavenging during wet precipitation is expected because of the moderate solubility
of tetrachloroethylene in water (150 mg/L). The major degradation process affecting vapor phase
tetrachloroethylene is photo-oxidation by hydroxyl radicals and the chlorine radicals formed by
the hydroxyl radical reaction (half-life on the order of weeks to months).
Fate in Aquatic Environments: The dominant fate of tetrachloroethylene released into
surface waters is volatilization (predicted half-life of hours to days (HSDB, 1996)).
Bioconcentration and sorption to sediments and suspended solids are not expected to be
significant transport/partitioning processes. Although biodegradation is not expected to be a
significant degradation process, any tetrachloroethylene that reaches the sediment will undergo
slow anaerobic biodegradation.
2.3.3.3.2 Transport and Partitioning
Soil Adsorption/Mobility: A Koc of 1,685 is predicted for tetrachloroethylene based on
its measured log octanol/water partition coefficient of 3.40. Actual Kocs calculated from studies
with various soils and sediments are less than 250 (HSDB, 1996). Based on the reported and
measured Kocs, tetrachloroethylene is expected to exhibit low to medium mobility in soil.
Therefore, tetrachloroethylene may leach slowly to the groundwater particularly in soils with low
organic content (HSDB, 1996).
Volatilization: The dominant removal mechanism for tetrachloroethylene in surface
waters is volatilization. The half-life will depend on wind and mixing conditions and is
estimated to range from 3 hours to 14 days in rivers, lakes, and ponds based on laboratory and
mesocosm experiments. Because of its high vapor pressure and relatively low soil adsorption
coefficient, tetrachloroethylene is expected to volatilize from soil surfaces and also from
suspended paniculate matter in the atmosphere (HSDB, 1996).
Bioconcentration: A bioconcentration factor of 226 is predicted for tetrachloroethylene
based on its measured log octanol/water partition coefficient of 3.40. Actual BCFs measured in
fish studies are less than 50. Therefore, bioconcentration in aquatic organisms should not be
significant and there is little potential for biomagnification in the food chain (HSDB, 1996).
2.3.3.3.3 Transformation and Degradation Processes
Biodegradation: Under aerobic conditions, tetrachloroethylene undergoes
biodegradation at a very slow rate with a half-life estimated at 6 months to a year. Little or no
degradation has been observed in several aerobic tests with acclimated or unacclimated inocula
nor in river die-away and mesocosm tests. Slow degradation under anaerobic conditions (half-
lives of weeks to months) has been demonstrated in laboratory screening tests.
Trichloroethylene is the major intermediate observed with traces of vinyl chloride and
dichloroethylene isomers also formed (HSDB, 1996; Howard et al., 1991).
39
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Photodegradation: Photolysis in the atmosphere or in aquatic environments is expected
to proceed very slowly if at all. Tetrachloroethylene does not absorb UV light at wavelengths
greater than 260 nm and thus will not directly photolyze. Based on measured rate data for the
vapor phase photo-oxidation reaction with hydroxyl radicals and with the chlorine radicals
formed during this reaction, the estimated half-life of tetrachloroethylene in the atmosphere is on
the order of weeks to months, although one study has reported complete degradation in one hour.
The main reaction products are phosgene, carbon tetrachloride, dichloroacetyl chloride, and
trichloroacetyl chloride (HSDB, 1996; Howard et al., 1991).
Hydrolysis: Tetrachloroethylene has no hydrolyzable groups. The rate constants at pH 3,
7, and 11 have been measured to be zero in one study. Another study reported a half-life of 9
months in purified, deionized water (HSDB, 1996; Howard et al., 1991)
2.4 HUMAN EXPOSURE AND POPULATION ESTIMATES
2.4.1 General U.S. Population
The most important routes of exposure to PCE for the general population are inhalation
of PCE in ambient air and ingestion of contaminated drinking water from contaminated aquifers
and drinking water distributed in pipelines with vinyl liners (HSDB, 1996). Available data
indicates that dermal exposure to PCE is not an important route of exposure for most people
(ATSDR, 1997b). Exposure from inhalation of ambient air varies according to location. In rural
and remote areas, background levels are generally in the low ppt range, and both low ppb and
high ppt are found in urban and industrial areas, and areas near point sources of emissions
(ATSDR, 1997b).
Results of several studies have indicated that indoor air is a more significant source of
exposure to PCE than outdoor air; reported concentrations in the air of four homes in North
Carolina were consistently higher than the outdoor concentrations (ATSDR, 1997b). The
detection of PCE in breast milk (see Section 2.3.3.2) indicates that infants may be exposed to
PCE through breast feeding (ATSDR, 1997b). For the general population, the estimated amount
of PCE that a person might breathe per day ranges from 0.08-0.2 mg/day and the most PCE
people might drink in water is 0.0001-0.002 mg/day (ATSDR, 1997b).
The EPA estimated that in 1985, 11,430,000 individuals (5.3 percent of the U.S.
population using municipal water supplies) in the U.S. were exposed to PCE at concentrations
>0.5 |ig/l. Assuming a 70 kg person drinks 2 L/day of water containing 0.5 ppb PCE, the daily
intake of PCE was 1 |ig or 0.014 |ig/kg/day (ATSDR, 1997b). Additionally, 874,000 individuals
were estimated to be exposed to levels >5 jig/1 (IARC, 1995). General population exposure from
ingestion of contaminated foods has been approximated by EPA assuming individual average
daily intakes of 0.753 kg dairy products; 0.262 kg meat, fish, and poultry; 0.073 kg fats and oils;
and 0.128 kg beverages (ATSDR, 1997b). The average daily intake of PCE was determined to
be between 0-4 jig from dairy products; 0-1 jig from meat, fish, and poultry; 0-9.5 jig from fats
and oils; and 0-0.06 |ig from beverages (ATSDR, 1997b).
40
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Showering or bathing with contaminated water is also a mechanism for PCE exposure.
Using results from a study and a model, it was estimated that the shower air would contain an
average of 1 ppm and the air above a bath tub would contain an average of 0.725 ppm if the
water contained 1 mg/L of PCE (ATSDR, 1997b). The model assumed that the shower or bath
used 100 liters of water, the air volume in the shower stall or above the bath tub was 3 m3, and
the shower flow rate was 6.667 L/minute (ATSDR, 1997b).
2.4.2 Occupational Exposure
Persons with the greatest chance of elevated exposure are those engaged in occupational
activities using PCE. In a survey conducted between 1981 and 1983 by NIOSH, it was estimated
that approximately 688,110 employees in 49,025 plants in the U.S. were potentially exposed to
PCE (ATSDR, 1997b). Further, in 1994 an independent industry estimate indicated that
approximately 450,000 workers in dry cleaning operations in the U.S. may be exposed (IARC,
1995). A NIOSH survey in 44 dry cleaning facilities showed PCE TWA exposures to machine
operators ranged from 4.0 to 149 ppm with a geometric mean of 22 ppm. Mean exposures to
pressers, seamstresses, and front counter workers were 3.3, 3.0, and 3.1 ppm, respectively
(ATSDR, 1997b).
Tetrachloroethylene has been identified in at least 771 of 1,430 hazardous waste sites that
have been proposed for inclusion in the EPA National Priorities List (NPL) (ATSDR, 1997b).
The number of sites evaluated is not known; the frequency of the sites are shown in Figure 2-2.
2.4.3 Consumer Exposure
In a study to determine potential sources of indoor air pollution, approximately 63 of
1,159 common household products were found to contain PCE (IARC, 1995). Products that
may contain PCE include adhesives; water repellents; fabric finishers; stain, spot, and rust
removers; and wood cleaners (ATSDR, 1997b). Other consumer products that have been found
to contain PCE are inks, polishes, rug and upholstery cleaners, sealants, and silicones.
2.5 CHAPTER SUMMARY
Table 2-7 summarizes the findings of TCE.
41
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FREQUENCY
1 TO 13 SITES
5B TO 64 SITES
11 II III) IB TO 30 SITES
7B SITES
Figure 2-2. Frequency of NPL Sites with Tetrachloroethylene Contamination (Source- ATSDR
1997b)
42
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Table 2-7. Tetrachloroethylene (Perchloroethylene) Summary
Uses
Production
Releases
Properties/Fate
Media Levels
General Population
Exposure
Special Population
Exposures
Estimates
Dry cleaning and metal degreasing
1.2xl08kg/yr
Air: 5.2 million Ib/yr
Water: 3,900 Ib/yr
Land: 4,300 Ib/yr
Volatile, water soluble, photo-oxidizes
slowly in air, no significant biodegradation
or bioconcentration
- Urban air: low ppb
- Rural air: low ppt
- Drinking water: 0.5-5 ug/L
- Food: 0.3-3 ug/kg
- Human blood: 0.1 9 ug/L
- Human milk: 6.2 ug/L
- Inhalation: 0.08-0.2 mg/d (urban)
- Water ingestion: 0.1-2ug/d
- Dairy: 0-4 ug/d
- Meat: 0-1 ug/d
- Fats/oils: 0-9 ug/d
- Nursing infants: ~4 ug/d
- Workers in production plants, degreasing
operations, dry cleaners (3-150) ppm
Support
Well documented in numerous studies,
recent information
1993 data
TRI (U.S. EPA, 1996) is primary source, so
current but uncertain due to self reporting
and exemptions
Well documented in numerous studies,
recent information
- Air data represents only 4 rural and 9
urban locations, dates unclear
- Blood data from NHANES III (n=590)
- n's and dates unclear for water, food, and
human milk data
- All estimates based on limited or unclear
monitoring data (see above)
- Representativeness of human milk data
unknown
- Worker data based on several recent
surveys
43
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3.0 1,1,1-TRICHLOROETHANE (METHYL CHLOROFORM)
3.1 CHEMICAL AND PHYSICAL PROPERTIES
The information/data presented in this section and the supporting references were
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).
3.1.1 Nomenclature
CAS No.:
Synonyms:
71-55-6
Chloroethene; chloroform; methyl-, chlorotene; ethane,
1,1,1-trichloro-; methyl chloroform; trichloroethane
Trade Names: alpha-t; algylen; baltana; gemalgene; inhibisol; solvent 111
3.1.2 Formula and Molecular Weight
Molecular Formula: C2H3C13
Molecular Weight: 133.43
3.1.3 Chemical and Physical Properties
Description:
Boiling Point:
Melting Point:
Density:
Colorless liquid (Patty, 1981-82); chloroform-like odor, sweetish
(Hazard Chem. Data Vol. II, 1984-85).
74.0°C @ 760 mm Hg (CRC Handbook Chem. & Physics, 1994-
95).
-30.4°C (CRC Handbook Chem. & Physics, 1994-95).
1.3376 @ 20°C/4°C (Merck Index, 11th Ed., 1989).
Spectroscopy Data: Index of refraction: 1.43838 @ 20°C/D (Merck Index, 10th Ed.,
1983); IR: 19461, NMR: 9171; Mass; 618 (Sadtler Research
Laboratories Prism Collection) (Weast, 1985).
Solubility:
Volatility:
Stability:
Soluble in acetone, benzene, methanol, carbon tetrachloride
(Merck Index, 11th Ed., 1989); 4,400 mg/1 in water @ 20°C
(Verschueren, 1983).
Vapor Pressure: 16.5 kPa @ 25°C (CRC Handbook, 1994-95)
Vapor Density: 4.63, relative (air = 1) (Verschueren, 1983).
No data.
44
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Reactivity: Although apparently stable on contact, mixtures with potassium
(or its alloys) with a wide range of halocarbons (including 1,1,2-
trichloroethane) are shock-sensitive and may explode with great
violence on light impact. Violent decomposition with evolution
of hydrogen chloride may occur when it comes into contact with
aluminum or its alloys with magnesium (Handbook Reactive
Chem. Hazards, 1985). Reacts with strong caustics; strong
oxidizers; chemically-active metals such as zinc, magnesium
powders; sodium and potassium; water (note: reacts slowly with
water to form hydrochloric acid) (NIOSH Pocket Guide Chem.
Haz, 1994).
Octanol/Water
Partition Coefficient: log Kow = 2.49 (Hansch. Log P Database, 1984)
3.1.4 Technical Products and Impurities
1,1,1-Trichloroethane is available commercially in the USA in technical and solvent
grades, which differ only in the amount of stabilizer added to prevent corrosion of metal parts
(IARC Monographs, V20:516, 1979). It is available as chlorothene SM (industrial grade) and
aerothene TT (aerosol grade) (Kuney. Chemcyclopedia, 1988).
Impurities include 1,2-dichloroethane, 1,1-dichloroethane, chloroform, carbon
tetrachloride, trichloroethylene, 1,1,2-trichloroethane, and vinylidene chloride (Stewart, RD, et
al., 1969).
Stabilized grades contain 3-8% stabilizers such as nitrom ethane, N-m ethyl pyrrole,
butylene oxide, 1,3-dioxolane, and secondary butyl alcohols (IARC Monographs, V20:516,
1979). Stabilizing agents which may be present in small amounts include: glycol diesters,
ketones, nitriles, dialkyl sulfoxides, dialkyl sulfides, dialkyl sulfites, tetraethyl lead, nitroaliphatic
hydrocarbons, 2-methyl-3-butyn-2-ol, tert-butyl alcohol, 1,4-dioxane, dioxolane, sec-butyl
alcohol, and monohydric acetylenic alcohols (NIOSH, 1976).
3.2 PRODUCTION AND USE
The information/data presented in this section and the supporting references were
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996) and from
ATSDR(1995).
3.2.1 Production
- (1990) 3.64 x 1011 g (ATSDR, 1995); (1992) 3.13 x 10ng (HSDB, 1996).
- Import Volume: (1991) 4.54 x 107 g; (1992) 5.99 x 109 g; (1993) 9.08 x 107 g
(ATSDR, 1995).
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- Export Volume: (1990) 5.2 x 1010 g; (1991) 7.37 x 1010 g; (1992) 6.34 x 1010 g; (1993)
3.44 x 1010 g (ATSDR, 1995).
3.2.2 Uses
1,1,1-Trichloroethane is used as a solvent for adhesives (including food packaging
adhesives) in pesticides, metal degreasing, textile processing, aerosols, lubricants, cutting oil
formulations, cutting fluids, shoe polishes, spot cleaners, stain repellents, drain cleaners, and
printing inks (ATSDR, 1995; HSDB, 1994). Its primary use in industry is for cold, dip, and
bucket cleaning and in vapor degreasing operations of electric and electronic instruments, fabrics,
wigs, and photographic film (ATSDR, 1995). It is also used as a chemical intermediate and for
on-site cleaning of printing presses, food packaging machinery, and molds (ATSDR, 1995;
HSDB, 1996). 1,1,1-Trichloroethane is also used extensively in household products that contain
solvents.
3.2.3 Disposal
Generators of waste containing this contaminant (i.e., EPA hazardous waste numbers
U226 and F002) must conform with USEPA regulations in storage, transportation, treatment, and
disposal of waste [40 CFR 240-280, 300-306, 702-799]. 1,1,1-trichloroethane is a waste
chemical stream constituent which may be subjected to ultimate disposal by controlled
incineration, preferably after mixing with another combustible fuel. Complete combustion to
prevent the formation of phosgene must be exercised (U.S. EPA, 1981 Engineering Handbook
for Hazardous Waste Incineration). 1,1,1 -Trichloroethane is a potential candidate for liquid
injection incineration at a temperature range of 650 to 1,600°C and a residence time of 0.1 to 2
seconds; for rotary kiln incineration at a temperature range of 820 to 1,600°C and residence times
of seconds for liquids and gases, and hours for solids; and for fluidized bed incineration at a
temperature range of 450 to 980°C and residence times of seconds for liquids and gases, and
longer for solids (HSDB, 1996). Chemical treatability study results indicates that the chemical
may be extractable with solvents, air and stream strippable, and treatable using biological
treatment (U.S. EPA, 1982, Management of Hazardous Waste). Other methods that have shown
promise for destruction of 1,1,1-trichloroethane are a combination of ozonation and ultraviolet
treatment for groundwater and homogeneous sonochemical treatment for aqueous waste
(ATSDR, 1995).
3.3 POTENTIAL FOR HUMAN EXPOSURE
3.3.1 Natural Occurrence
1,1,1-Trichloroethane is not known to occur as a natural product.
3.3.2 Occupational
Humans may be exposed to 1,1,1-trichloroethane dermally and by inhalation of
contaminated air at the workplace (HSDB, 1996).
46
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3.3.3 Environmental
1,1,1-Trichloroethane is likely to enter the environment from air emissions or in the
wastewater from its production or use in vapor degreasing, metal cleaning, and other operations.
It can also enter the environment in leachates and volatile emissions from landfills (HSDB,
1996). Process and fugitive emissions may result from the use of both consumer and industrial
products (ATSDR, 1995). Because 1,1,1-trichloroethane is used as a solvent in many products
and is very volatile, it is most frequently found in the atmosphere due to volatilization from
production and use (ATSDR, 1995).
3.3.3.1 Environmental Releases
Air: Trichloroethane has been found in the ambient air around chemical manufacturing
areas, in remote and rural areas, and around suburban sites. Toxic Release Inventory (TRI) data
are shown in Table 3-1.
The TRI data for 1,1,1-trichloroethane have been correlated with industrial source code
(SIC Codes) and shows that emissions of this chemical are associated with 122 different
industrial classifications (ATSDR, 1995). The TRI data shown in Table 3-1 indicate that 1,1,1-
trichloroethane emissions to air ranged from 166.3 million pounds in 1987 down to 38.1 million
pounds in 1994 (TRI, 1996).
Table 3-1. Releases of 1,14-Trichloroethane (Ibs)
Year
1987
1988
1989
1990
1991
1992
1993
1994
Number of
Reporting
Facilities
3494
3915
4201
4210
3732
3210
2111
1207
Fugitive Air
Releases
90,428,647
92,995,587
94,100,022
85,672,408
72,670,441
57,760,109
33,199,831
20,070,741
Stack Air
Releases
75,825,060
87,654,575
86,086,417
83,0994,85
71,770,764
59,857,572
31,568,263
17,981,336
Surface
Water
Release
37,181
95,624
27,564
16,984
22,308
13,707
11,146
1,980
Underground
Injection
28,325
1,000
2,318
1,586
2,805
561
2528
102
Land
Disposal
199,191
204,923
70,547
62,446
174,730
76,131
42,743
2,732
POTW
Transfer
412,010
305,358
312,515
173,444
253,812
119,263
60,463
6,439
Other
Transfers
32,141,143
19,389,542
16,815,840
13,099,706
39,451,571
32,080,182
20,842,953
11,387,618
Total
199,071,557
200,646,609
197,415,223
182,126,059
184,346,431
149,907,525
85,727,927
49,450,948
Source: TRI, 1996.
47
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Other sources for small emissions of 1,1,1-trichloroethane to the atmosphere include coal
fired plants, incineration of medical waste, incineration of industrial waste containing waste
solvents and certain plastics, and municipal wastewater sludge (ATSDR, 1995). When contained
in consumer products, 1,1,1-trichloroethane can be released to the atmosphere during application,
drying, or curing of the consumer products.
Water: 1,1,1-Trichloroethane has been reported in groundwater, surface water, and
drinking water in the United States. It has also been reported in seawater. TRI data on water
releases are presented in Table 3-1.
Other Media: Levels of 1,1,1-trichloroethane has been reported in raw, processed, and
prepared foods. Additionally, it has been detected in soils and sediments (ATSDR, 1995). TRI
estimates of releases to land are presented in Table 3-1.
3.3.3.2 Monitored Environmental Media Levels
Air: Numerous studies have reported levels of 1,1,1-trichloroethane in air throughout the
U.S. Monitoring data have been reported with sampling dates ranging primarily from years 1972
through 1986. However, there are several studies for years 1987 through 1990. Measured
concentrations in urban air range from 0.1 to 1 ppb; for large urban areas or areas near hazardous
waste sites, levels < 1,000 ppb have been observed (ATSDR, 1995; HSDB, 1996). Level of this
chemical in rural areas typically are <0.2 ppb. ATSDR (1995c) provides a summary of
monitored levels in ambient air in the U.S. that includes sampling dates, number of samples,
concentrations (range and mean), study location, and author. Level of 1,1,1-trichloroethane in
indoor air seems to depend on parameters such as outdoor concentration, age of building,
individual practices, and building air exchange characteristics (ATSDR, 1995).
Water: 1,1,1-Trichloroethane has been detected in surface water, groundwater, drinking
water, rain, snow, effluent, and urban runoff (ATSDR, 1995). The levels detected in surface
water and groundwater depends upon the sampling point location. For groundwater random
samples, levels have ranged from 0 to 18 ppb; groundwater samples obtained near sources of
release to soil have been as high as 11,000 ppb (ATSDR, 1995). Drinking water from reported
surface or groundwater sources contained concentrations of 0.01 to 3.5 ppb (ATSDR, 1995).
Levels in raw surface water in 105 U.S. cities were 0.2 ppb (median) and 1.2 ppb
(maximum) (HSDB, 1996). In studies of surface water near industrialized sites, the measured
levels ranged up to 334 ppb (HSDB, 1996).
Other Media: 1,1,1-Trichloroethane has been detected in human adipose tissues (not
detected - 830 ppb); milk; blood; and breath. It has been found in foods which include
unprepared, uncooked foods; fruits; nuts; dairy products; etc. A range of the mean values for
levels of 1,1,1-trichloroethane reported in ATSDR (1995) are shown in Table 3-2 for some of
these foods. 1,1,1-Trichloroethane has been found in average concentrations in fish at 2.7 ppm;
shrimp at <0.3 ppm; and clams and oysters ranging from 39 to 310 ppm.
48
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Table 3-2. Level of 1,1,1-Trichloroethane in Food
Food Type
Concentration (ppb) (Range of Means)
Cereals
Vegetables (processed/cooked)
Baked goods (breads, cookies, cakes)
Dairy products
Nuts/nut products
Meats, meat dishes (cooked/processed)
Fruits (raw/dried)
Infant/toddler blend
3-35
1-9
2-40
1-520
10-228
2-76
2-32
6
Source: ATSDR, 1995.
The National Health and Nutrition Examination Survey (NHANES IE) (1988-91) is a
national survey of the U.S. civilian non-institutionalized population. It provides data to monitor
changes in dietary, nutritional, and health status of the U.S. population. As part of this survey,
data were analyzed for the level of selected VOCs in the blood. Figure 3-1 presents the level of
1,1,1-trichloroethane in blood at selected percentiles.
Levels of 1,1,1-trichloroethane in soils have been measured in grab samples from two
former sludge lagoons of a solvent recovery operation, at a residence near a landfill, at a
production facility, and at several NPL sites. The reported levels were 23,000 to 120,000 ppb at
the lagoon, up to 230,000 ppb at the NPL sites, and 0.06 to 1.0 ppb at the production facility
(ATSDR, 1995). Levels of 1,1,1-trichloroethane in sediment have been reported up to 2 ppb for
non-NPL sites and ranged from 50 to 2,500 ppb at an NPL site (ATSDR, 1995). Monitoring data
for the occurrence of 1,1,1-trichloroethane in soil is limited and may be due to its rapid
volatilization from soil and/or its ability to leach through soil (ATSDR, 1995).
3.3.3.3 Environmental Fate and Transport
3.3.3.3.1 Summary
The summary is based on the data presented in the subsequent fate and transport
subsections.
Fate in Terrestrial Environments: The dominant fate of 1,1,1-trichloroethane released
to surface soils is volatilization. Because of its moderate mobility in soils, 1,1,1-trichloroethane
introduced into soil (e.g., landfills) has the potential to migrate through the soil into groundwater.
Fate in the Atmosphere: In the atmosphere, 1,1,1-trichloroethane is expected to be
present primarily in the vapor phase rather than sorbed to particulates because of its moderate
vapor pressure. Removal by scavenging during wet precipitation is expected because of the
moderate solubility of 1,1,1-trichloroethane in water; 40 percent reductions in air concentrations
have been reported on rainy days. The major degradation process affecting vapor phase 1,1,1-
trichloroethane is photo-oxidation by hydroxyl radicals (half-life on the order of years). Due to
its persistence, 1,1,1-trichloroethane will disperse over long distances and slowly diffuse into the
49
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0.5
S0.4
a
f 0.3
2
10.2
0.1
0
5
10 20 30 40 50 60 70 80 90
Population Percentile
Source: NHANES III (Ashley, D., 1997, CDC). N=574
Figure 3-1. Concentration of 1,1,1-Trichloromethane in Blood at Selected Population Percentiles
50
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stratosphere where it would be rapidly degraded. The global atmospheric average half-life has
been estimated to be 6 to 7 years (HSDB, 1996; ATSDR, 1995).
Fate in Aquatic Environments: The dominant fate of 1,1,1-trichloroethane released to
surface waters is volatilization (predicted half-life of hours to weeks depending on wind and
mixing conditions). Bioconcentration and sorption to sediments and suspended solids are not
expected to be significant transport/partitioning processes relative to volatilization.
3.3.3.3.2 Transport and Partitioning
Soil Adsorption/Mobility: The mean Koc range of 1,1,1-trichloroethane in a silty clay
soil and sandy loam soil is 81 to 89. 1,1,1-Trichloroethane is sorbed strongly to peat moss but
not at all to sand. From these measured Kocs and the fact that 1,1,1-trichloroethane is frequently
detected in groundwater, it can be concluded that 1,1,1-trichloroethane is not sorbed strongly by
soils. It can be expected to leach to groundwater particularly in soils with low organic content
(HSDB, 1996).
Volatilization: The dominant removal mechanism for 1,1,1-trichloroethane in surface
waters is volatilization. The half-life will depend on wind and mixing conditions and is
estimated to range from 3 to 29 hours in rivers, 4 to 12 days in lakes, and 5 to 11 days in ponds
based on laboratory experiments. Because of its moderate vapor pressure and relatively low soil
adsorption coefficient, 1,1,1-trichloroethane is expected to volatilize from soil and also from
suspended particulate matter in the atmosphere. The cumulative evaporation loss of a mass of
1,1,1-trichloroethane situated 1.0 to 1.3 meters beneath a soil surface for one year has been
estimated to be 61.8 percent in sandy soil and 4.9 percent in clay soil (HSDB, 1996).
Bioconcentration: A bioconcentration factor of 8.9 was measured in a 28-day test with
bluegill sunfish. BCFs measured in fish studies are less than 10 for structurally similar
halogenated aliphatic compounds. Therefore, bioconcentration in aquatic organisms should not
be significant and there is little potential for biomagnification in the food chain (HSDB, 1996).
3.3.3.3.3 Transformation and Degradation Processes
Biodegradation: 1,1,1-Trichloroethane has been shown to undergo reductive
dechlorination to 1,1-dichloroethane and chloroethane under anaerobic conditions in laboratory
tests using acclimated microorganisms with half-lives on the order of weeks to months.
Biodegradation under aerobic conditions has also been demonstrated to occur at a slow rate
(weeks to months) with vinylidene chloride formed as a degradation product (HSDB, 1996;
Howard etal., 1991).
Photodegradation: Direct photolysis is not important in the troposphere since 1,1,1-
trichloroethane does not absorb light above 290 nm. In the stratosphere, photolysis is important
and 1,1,1-trichloroethane will be rapidly degraded. Photolytic degradation has not been observed
in aqueous media exposed to sunlight for one year. Based upon measured rate constants for the
vapor phase photo-oxidation reaction with photochemically produced hydroxyl radicals, the half-
life of 1,1,1-trichloroethane in the atmosphere is on the order of years. Products of
51
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photodegradation include phosgene, chlorine radicals, and hydrochloric acid. Degradation is
reported to be greatly increased by exposure to ozone and chlorine but no quantitative data are
available (HSDB, 1996; Howard et al., 1991).
Hydrolysis: The hydrolysis half-life of 1,1,1-trichloroethane has been reported to range
from 0.73 to 1.1 years. The half-life in water containing suspended sediment is 1.2 years. The
product of hydrolysis is vinylidene chloride (HSDB, 1996; Howard et al., 1991).
3.4 HUMAN EXPOSURE AND POPULATION ESTIMATES
3.4.1 General U.S. Population
The general population may be exposed to 1,1,1-trichloroethane through the inhalation of
ambient air and inhalation of indoor air contaminated by use of household products containing
this chemical. The general population may be potentially exposed to 1,1,1-trichloroethane
through emissions from hazardous waste sites. 1,1,1-Trichloroethane has been identified at 696
of 1,408 NPL hazardous waste sites. The frequency of these sites in the U.S. is shown in Figure
3-2. Inhalation is expected to be the predominant exposure route; however, exposure can also
occur through ingestion of contaminated foods and drinking water and through dermal contact.
Therefore, available data suggest that because of its ubiquitous occurrence in the environment
and its use in many consumer products, much of the general population is exposed to low levels
of 1,1,1-trichloroethane (ATSDR, 1995).
Exposure of the general population from the commercial use of products may potentially
be more significant than exposure resulting from industrial release. ATSDR reported maximum
exposure levels to this chemical during a variety of personal activities: visiting the dry cleaners
(185 ppb); working in chemistry lab (18.5 ppb) and as lab technician (12 ppb); using pesticides
(20 ppb); and using paint (20 ppb) (ATSDR, 1995).
The average daily intake (ADI) for air is assumed in HSDB (1996) to be: in rural areas
(0.110 ppb) - 12.2 jig; urban/suburban areas (0.420 ppb) - 46.5 jig; for residents in source
dominated areas assume (1.2 ppb) - 133.0 jig. The ADI for water is assumed in HSDB (1996) to
be: surface water source (0.4 ppb) - 0.8 jig; groundwater source (2.1 ppb) - 4.2 jig. ATSDR
(1995) assumed an average urban air concentration of 1,1,1-trichloroethane of 1 ppb and the
average rural concentration of 0.1 ppb and calculated daily nonoccupational intakes of 108 and
10.8 jig/day, respectively. The estimate is based on an average human air intake of 20 m3/day.
ATSDR (1995) noted that Wallace et al. (1985) has determined the mean daily air exposures for
12 subjects at 2 urban areas at 37 mg and the mean daily intake from all sources (air, food, water)
between 50 and 1,000 mg/day.
3.4.2 Occupational Exposure
NIOSH estimated in a 1981-1983 survey that approximately 2,528,300 workers were
potentially exposed to 1,1,1-trichloroethane in the U.S. (ATSDR, 1995). Trichloroethane
concentration in the air of various industries (degreasing, manufacture of electric components,
52
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March 29, 200163
FREQUENCY
1 TO IB SITES
SO TO SB SITES
16 TO 28 SITES
6O TO 71 SITES
Figure 3-2. Frequency of NPL Sites with 1,1,1-Trichloromethane Contamination (Source:
ATSDR, 1995)
53
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mixing and application of commercial resins, spray painting, and gluing) applications of 1,1,1-
trichloroethane might result in elevated levels of exposure (ATSDR, 1995). Occupational
exposures predominantly occur through inhalation pathways.
3.4.3 Consumer Exposure
In a shelf survey for household products containing methylene chloride, 14.1 percent of
the samples and 47.8 percent of the product categories contained 1,1,1-trichloroethane (HSDB,
1996). Consumer products that may contain this chemical include typewriter correction fluid,
fingernail polish, paint thinner, caulking compounds, lacquer, paint removers, and antifreeze. A
list of common household products that contain 1,1,1-trichloroethane is presented in Table 3-3.
Table 3-3. 1,1,1-Trichloroethane in Common Household Products
Product
Adhesive cleaners
Adhesives
Aerosol spray paint
Battery terminal protectors
Belt lubricants
Brake cleaners
Carburetor cleaners
Circuit board cleaners
Door spray lubricants
Drain cleaner (nonacid)
Electric shaver cleaners
Engine degreasers
Fabric finishes
Gasket removers/adhesives
General purpose spray degreasers
General purpose liquid cleaners
Ignition wire driers
Lubricants
Miscellaneous nonautomotive
Miscellaneous automotive
Concentration
(% w/w)
0.1-95.0
0.2-121.1
0.2-1.0
37.1
11.4-72
0.4-75.6
0.2-0.3
NS
95.6
97.8
2.5-20.3
0.2
77.9-85.1
0.2-1.0
0.1-71.4
72.7-126.7
24.3-43.6
0.1-104.5
12.5-67.5
0.3-0.4
Product
Oven cleaners
Paint removers/strippers
Primers
Rust removers
Silicone lubricants
Specialized aerosol cleaners
Spot removers
Spray shoe polish
Stereo/record player cleaners
Suede protectors
Tape recorder cleaners
Tire cleaners
Transmission cleaner/lubricant
TV/computer screen cleaners
Typewriter correction fluid
VCR cleaners
Video disk cleaners
Water repellents
Wood cleaners
Woodstain/varnishes/fmishes
Concentration
(% w/w)
97
0.1-25.7
1.2-61.8
0.7
0.2-91.1
0.2-83.8
10.5-110.8
11.4-62.3
0.7
4.8-118.5
0.2-101.5
0.1-90.3
113
0.3
6-110
97.8
0.6
0.2-116.2
12.3-20.4
0.1-21.4
NS = not specified
Source: ATSDR (1995)
3.5 CHAPTER SUMMARY
Table 3-4 summarizes the findings of 1,1,1-trichloroethane.
54
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Table 3-4. 1,1,1-Trichloroethane (Methyl Chloroform) Summary
Uses
Production
Releases
Properties/Fate
Media Levels
General Population
Exposure
Special Population
Exposures
Estimates
Metal cleaning and degreasing, many
other solvent applications, chemical
intermediate, many household
products
3.13x 108kg
49.45 x 106 Ibs in 1994, mostly to air
Volatile, no significant bio-
concentration, slow bio-degradation
Air: outdoor urban - 0.545-5.45
|lg/m3
outdoor rural - < 1.09 |lg/m3
Drinking Water: 0.01-3.5 ppb
Groundwater: 0-18 ppb
Some data on food and in many
household items
Inhalation: rural - 12.2 |lg/d
urban/suburban - 46.5
|ig/d
Water ingestion: surface water - 0.8
|ig/d; groundwater - 4.2 |ig/d
Workers in dry cleaning, chemistry
labs, lab tech, painting
Support
Well documented in recent
studies
1992 data
TRI (U.S. EPA, 1996) data is
primary source, so data are
current but uncertain due to self
reporting and exemptions
Well documented in recent
studies
Data is dated and represent
uncertain number of samples
Values based on limited data
Data limited
55
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4.0 1,2-DICHLOROETHYLENE
4.1 CHEMICAL AND PHYSICAL PROPERTIES
The information/data presented in this section and the supporting references were
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).
4.1.1 Nomenclature
CAS No.: 540-59-0
Synonyms: 1,2-dichloroethene; acetylene dichloride; ethene, 1,2-dichloro
Trade Names: Diform, NCI.C5603
4.1.2 Formula and Molecular Weight
Structural Formula: C2H2C12
Molecular Weight: 96.95
4.1.3 Chemical and Physical Properties
Description: Colorless liquid (usually a mixture of cis and trans isomers);
slightly acrid, chloroform-like odor (NIOSH Pocket Guide Chem.
Haz., 1994).
Boiling Point: 55°C (Merck Index, 9th Ed., 1976).
Melting Point: -50°C (Patty. Indus. Hyg. & Tox., 3rd Ed., 1981-82).
Density: 1.27 @ 25°C (liquid) (CHRIS Hazard Chem. Data Vol. II,
1984-5).
Spectroscopy Data: IR: 3645 (Sadtler Research Laboratories Prism Collection); Mass:
203 (Atlas of Mass Spectral Data) (Weast. 1985. CRC Handbook
Data Organic CPDS, Vol. I, II).
Solubility: Soluble in alcohol, ether, acetone (cis- and trans-1,2-
dichloroethylenes) (CRC Handbook Chem. & Physics, 1994-1995).
Soluble in most organic solvents (Merck Index, 11th Ed., 1989)
Volatility: Vapor Pressure: 324 torr at 25°C (Patty. Indus. Hyg. & Tox, 3rd.
Ed., Vol. 2A, 2B, 2C, 1981-1982).
Stability: Gradually decomposed by air, light, and moisture, forming HC1
(Merck Index, 10th Ed., 1983).
56
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Reactivity: The reaction of 1,2-dichloroethylene and potassium hydroxide
produces chloroacetylene, which is explosive and spontaneously
flammable in air. It is highly toxic. The addition of sodium,
caustic, or caustic solution to 1,2-dichloroethylene may form
monochloroacetylene which is spontaneously flammable in air
(Fire Protect Guide Hazard Matls, 10th Ed., 1991). May release
explosive chloroacetylene by the contact with copper or copper
alloys (Tox & Hazard Indus Chem Safety Manual, 1988).
Incompatible with alkalies, difluoromethylene dihypofluorite, and
nitrogen tetraoxide (Sax, 1984). Reactive with strong oxidizers,
strong alkalis, potassium hydroxide, copper (Note: usually contains
inhibitors to prevent polymerization) (NIOSH Pocket Guide Chem
Haz, 1994).
Octanol/Water
Partition Coefficient: No data
4.1.4 Technical Products and Impurities
1,2-Dichloroethylene is produced in the following grades: technical; As cis, trans; and as
a mixture of both (Sax, 1987). Technical 1,2-dichloroethylene consists of 60%, 40% cis- trans-
isomers (ACGffl, 1985).
4.2 PRODUCTION AND USE
The information/data presented in this section and the supporting references were
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996) and ATSDR
(1996a).
4.2.1 Production
No information concerning U.S. production, import, or export volumes was identified.
4.2.2 Uses
1,2-Dichloroethylene has been used as a solvent for fats, phenol, camphor; for retarding
fermentation (Merck Index, 11th Ed., 1989); solvent for natural rubber; coolant in refrigeration
plants; low temperature solvent; and a special-purpose solvent (HSDB, 1996; ATSDR, 1996a).
It has also been used in extraction of dyes, caffeine, fats from animal flesh; perfumes; lacquers;
thermoplastics; and organic synthetics (Sax, 1987). Although cis- and trans-isomers of 1,2-
dichloroethylene have had use as solvents and chemical intermediates, neither of the isomers has
developed wide industrial usage in the U.S., partly because of their flammability (Patty. Indus
Hyg & Tox, 3rd Ed., Vol. 2A, 2B, 2C, 1981-82). 1,2-dichloroethylene obtained as a byproduct is
used as feed stock for the synthesis of tri- and perchloroethylene (Ullmann's Encyc Indust Chem,
5th Ed., Vol. Al, 1985-present). It also has miscellaneous uses such as a liquid dry cleaning
57
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agent; cleaning agent for printed circuit boards; for food packaging adhesive; and germicidal
fumigant. The extent of these continued uses has not been confirmed (ATSDR, 1996a).
In applications where dichloroethylenes could be used as solvents and for low
temperature extraction processes, they have been replaced with methylene chloride (Ullmann's
Ency Indus Chem, 5th Ed., 1985-present).
4.2.3 Disposal
1,2-Dichloroethylene is a potential candidate for rotary kiln incineration at a temperature
range of 820 to 1,600°C and residence times of seconds for liquids and gases and hours for
solids; for fluidized bed incineration at a temperature range of 450 to 980°C and residence times
of seconds for liquids and gases, and longer for solids; and for liquid injection incineration at a
temperature range of 650 to 1,600°C and a residence time of 0.1 to 2 seconds (trans-1,2-
dichloroethylene) (USEPA. 1981. Engineering Handbook for Hazardous Waste Incineration).
This compound should be susceptible to removal from wastewater by air stripping
(USEPA/ORD. 1980. Innovative and Alternative Technology Assessment Manual).
Incineration is a disposal method, preferably after mixing with another combustible fuel. Care
must be exercised to assure complete combustion to prevent the formation of phosgene. An acid
scrubber is necessary to remove the halo acids produced. The recommendable method is
incineration (Un. Treat Disposal Methods Waste Chem Data Series No. 5, 1985).
At the time of review, criteria for land treatment or burial (sanitary landfill) disposal
practices are subject to significant revision. Prior to implementing land disposal of waste residue
(including waste sludge) consult with environmental regulatory agencies for guidance on
acceptable disposal practices (HSDB Scientific Review Panel; HSDB, 1996).
4.3 POTENTIAL FOR HUMAN EXPOSURE
4.3.1 Natural Occurrence
No information on natural occurrence of 1,2-dichloroethylene was identified.
4.3.2 Occupational
Occupational potential for exposure is reported in Section 5 and Section 6 for the cis and
trans isomers, respectively.
4.3.3 Environmental
Most of the 1,2-dichloroethylene released into the environment will eventually enter the
groundwater or the atmosphere (ATSDR, 1996a). Releases to the environment are a result of
process and fugitive emissions from production and use as a chemical intermediate; leaching
from landfills; evaporation from wastewater streams, landfills, and solvents; emissions from
heating or combustion PVC and vinyl copolymers; and formation via anaerobic biodegradation
of some chlorinated solvents (ATSDR, 1996a).
58
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4.3.3.1 Environmental Releases
Air: Releases of 1,2-dichloroethylene to air are usually the result of emissions from
industrial production and use facilities, contaminated waste disposal sites, and emissions from
pyrolysis/combustion of certain plastic resins. TRI estimates for releases to the air in 1991
totaled 44,782 pounds (>99 percent of total TRI estimated environmental releases) (ATSDR,
1996a).
Water: 1,2-dichloroethylene may be released to surface waters, groundwater, and has
been detected in drinking water. It may be released to surface waters through runoff from
contaminated waste disposal sites, wastewater from industrial sources, and from some POTWs.
According to TRI estimates for 1993, a total of 28 pounds of 1,2-dichloroethylene (<0.1 percent
of total releases to the environment) were released to water from reporting manufacturing and
processing facilities (ATSDR, 1996a).
1,2-dichloroethylene may be released to groundwater due to leaching from contaminated
waste disposal sites and cracked sewer interceptors carrying industrial waste contaminated with
this chemical. It may also be released to groundwater as a result of anaerobic degradation of
highly chlorinated ethenes (TCE, PCE) and ethanes present in groundwater (ATSDR, 1996a).
1,2-dichloroethylene's presence in drinking water may be attributed to raw water source
contamination; however, there is little documentation of direct groundwater contamination.
Other Media: The cis and trans isomers of 1,2-dichloroethylene are released to soil from
disposal of waste contaminated with this chemical. Additionally, they may also be found in
landfills from anaerobic biodegradation of PCE, TCE, 1,1,1-trichloroethane, and 1,1,2,2-
tetrachloroethane (ATSDR, 1996a). TRI estimates for 1993 indicated that no 1,2-
dichloroethylene was released to land from manufacturing and processing facilities (ATSDR,
1996a). Available data are not sufficient to estimate the amount of 1,2-dichloroethylene released
to soil and to sediments.
4.3.3.2 Monitored Environmental Media Levels
Air: 1,2-dichloroethylene has been detected in ambient air samples in various urban
locations throughout the U.S. It has also been detected in the gas from various landfills in the
U.S. Levels found in the ambient air ranged from <0.1 to 2.6 ppb, and levels in the gas from
landfills ranged from 70 ppb (mean) to 75,600 ppb (maximum values; trans isomer) (ATSDR,
1996a). 1,2-dichloroethylene detected in the indoor air of 2 studies were 0.015 ppb and 8.1 ppb,
respectively (ATSDR, 1996a). The data reported in most studies were not isomer-specific. In
the EPA National Ambient Database update, outdoor ambient concentrations of 1,2-
dichloroethylene averaged 0.326 ppb. A median value of 0.037 ppb was also reported. These
reported levels were base on 161 data points (ATSDR, 1996a). According to ATSDR (1996a),
the efficiency of waste treatment plants has improved and loadings to receiving waters have
decreased. But, this decrease has often resulted in increased emissions to the atmosphere as the
volatile constituents are removed through processes such as air stripping (ATSDR, 1996a).
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Water: Concentrations of 1,2-dichloroethylene found in water reported in ATSDR
(1996a) are described below. These ranges are based on various studies.
• Surface water: not detected - 1,370.5 ppb (maximum value)
• Groundwater: 0.25-0.28 ppb (average value) - 50,000 ppb (maximum value; trans
isomer)
• Drinking water: trace - 64 ppb (maximum value - groundwater source)
• Leachate: 1.4-470 (cis isomer) ppb - 45-800 ppb (average concentration of
leachate; maximum value)
• Aqueous Lagoon: 50 ppb (trans isomer)
• Wastewater at various industries: 1.6 ppb (cis isomer) - 2,265 ppb (trans isomer;
median value)
• Rainwater: 0.230 ppb (1 sample)
A maximum concentration of 33 ppb for cis isomer was found in a shallow unconfirmed aquifer
receiving waste water from metal plating operations. The EPA Contract Laboratory Program
(CLP) data base has reported trans isomer mean concentrations ranging from 5 to 4,000 ppb at 8
of 357 hazardous waste sites.
Other Media: Trans 1,2-dichloroethylene concentrations ranging from 22 to 55 g/L have
been detected in municipal sludge from various treatment throughout the United States (1996a),
while 0.04 ppm (mean value) to 0.05 ppm (maximum value) of 1,2-dichloroethylene were found
in fish tissues from Commencement Bay in Tacoma, Washington (1996a). Monitoring data for
levels of 1,2-dichloroethylene in soil are very limited. The mean concentration range of 5 to
4,000 ppb was reported at 87 of 357 hazardous waste sites (ATSDR, 1996a). However, the trans
isomer was reported in all cases (ATSDR, 1996a). According to ATSDR (1996a), the available
data for 1,2-dichloroethylene in soil are limited to data from hazardous waste site monitoring.
4.3.3.3 Environmental Fate and Transport
4.3.3.3.1 Summary
The summary is based on the data presented in the subsequent fate and transport
subsections.
Fate in Terrestrial Environments: The dominant fate of 1,2-dichloroethylene released
to surface soils is volatilization. Some 1,2-dichloroethylene may leach downward in the soil
column because of the high water solubility and low Koc values of the two isomers. Also, 1,2-
dichloroethylene is formed under anaerobic conditions in soil, groundwater, and sediments as a
breakdown product from microbial reductive dehalogenation of the common industrial solvents
trichloroethylene, tetrachloroethylene, and 1,1,2,2,-tetrachloroethane. The fate of 1,2-
dichloroethylene in subsurface soils and groundwater is slow anaerobic degradation with the
formation of vinyl chloride as a degradation product.
Fate in the Atmosphere: In the atmosphere, 1,2-dichloroethylene is expected to be
present in the vapor phase rather than sorbed to particulate matter. Removal by scavenging
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during wet precipitation is expected because of the high solubility of the two isomers. The
predominant degradation process affecting both isomers is photo-oxidation by hydroxyl radicals.
Predicted half-lives for this reaction are 3.6 and 8 days for the trans- and cis- isomers,
respectively.
Fate in Aquatic Environments: The dominant fate of 1,2-dichloroethylene released to
surface waters is volatilization (predicted half-life of 3 hours). Bioconcentration and sorption to
sediments and suspended solids are not expected to be significant transport/partitioning
processes. Although biodegradation is not expected to be a significant degradation process, any
1,2-dichloroethylene that reaches the sediment will undergo slow anaerobic biodegradation.
4.3.3.3.2 Transport and Partitioning
Soil Adsorption/Mobility: The relatively low predicted soil adsorption coefficients (Koc)
for cis- and trans-1,2-dichloroethylene, 36 and 49, respectively, indicate that adsorption of the
1,2-dichloroethylene isomers to soil, sediment, and suspended solids is not a significant fate
process. As a consequence, these isomers should show high mobility in soil (HSDB, 1996;
Howard, 1993).
Volatilization: The dominant removal mechanism for the dichloroethylene isomers in
surface waters is volatilization. The Henry's Law constants for cis- and trans- dichloroethylene
are 0.00408 and 0.00938, respectively. Based on these values, the estimated half-lives for
volatilization of cis- and trans-dichloroethylene from a model river 1 m deep with a 1 m/sec
current and a 3 m/sec wind speed are 3.1 and 3.0 hours, respectively. Similarly, the volatilization
half-lives from aim deep body of water predicted from laboratory volatilization studies are 5.0
and 6.2 hours, respectively. Because of their high vapor pressures, both isomers are also
expected to readily volatilize from soil surfaces and also from suspended particulate matter in the
atmosphere (HSDB, 1996; Howard, 1993).
Bioconcentration: Bioconcentration factors of 15 and 22 are predicted for cis- and trans-
dichloroethylene, respectively, based on their respective octanol/water partition coefficients.
Therefore, bioconcentration in aquatic organisms should not be significant and there is little
potential for biomagnification in the food chain (HSDB, 1996; Howard, 1993).
4.3.3.3.3 Transformation and Degradation Processes
Biodegradation: The results of most aerobic biodegradation studies indicate that 1,2-
dichloroethylene is recalcitrant to aerobic degradation in soil and water (i.e., half-lives on the
order of months); however, one study reported half-lives on the order of days to weeks. Several
studies have demonstrated that both isomers will undergo slow anaerobic biodegradation in soils
and sediments with half-lives on the order of months or longer. Vinyl chloride is a degradation
product (HSDB, 1996; Howard, 1993; Howard et al., 1991).
Photodegradation: In the atmosphere, cis- and trans-1,2-dichloroethylene react with
photochemically produced hydroxyl radicals resulting in half-lives of 8 and 3.6 days,
respectively. The only product positively identified from this reaction is formyl chloride. Photo-
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oxidation through reaction with ozone is much slower, on the order of months. Because cis- and
trans-1,2-dichloroethylene absorb only a small amount of UV light in the environmentally
significant range, direct photolysis is an insignificant fate process (HSDB, 1996; Howard, 1993;
Howard et al., 1991).
Hydrolysis: The two isomers of 1,2-dichloroethylene contain no hydrolyzable groups
(Howard et al., 1991)
4.4 HUMAN EXPOSURE AND POPULATION ESTIMATES
4.4.1 General U.S. Population
The general population may be exposed to low levels ranging from 0.013 to 0.076 ppb of
1,2-dichloroethylene through inhalation of contaminated air in urban areas (ATSDR, 1996a).
ATSDR (1996a) calculated the corresponding average daily intake of 1 to 6 |ig/day based on an
average air intake of 20 m3/day. HSDB (1996) has reported the following assumed
concentrations for average daily intake:
Air intake - assume air concentration of 68 ppt (5.4 jig)
Water intake - assume water concentration from contaminated sources of 1.1 ppb
(2.2 jig) when drinking water is contaminated
The general population with potentially the highest exposures are those living near
production/processing facilities, municipal wastewater treatment plant, hazardous waste sites,
and municipal landfills. Potential exposure exists in air downwind of these sites and in the
contaminated drinking water from groundwater down gradient from the sites (ATSDR, 1996a).
Cis-l,2-dichloroethylene has been identified in 146 of the 1,430 current or former EPA
National Priorities List (NPL) hazardous waste sites and trans -1,2-dichloroethylene has been
identified in at least 563 of the current or former NPL sites (ATSDR, 1996a). Although the
number of sites evaluated for this chemical is not known, the frequency of these sites has been
determined and is presented in Figure 4-1.
4.4.2 Occupational Exposure
According to a 1981-1983 NIOSH survey, a statistical estimate of 215 workers in the
U.S. are potentially exposed to 1,2-dichloroethylene (mixture of cis and trans isomers) in the
workplace (ATSDR, 1996a). An estimated 61 workers are potentially exposed to the cis isomer
(ATSDR, 1996a). An estimate for potential occupational exposure to the trans isomer was not
estimated from the survey.
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Figure 4-1. Frequency of NPL Sites with 1,2-Dichloroethene (Unspecified) Contamination
(Source: ATSDR, 1996a)
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4.4.3 Consumer Exposure
Readily available data were not found on consumer exposures for 1,2-dichloroethylene.
4.5 CHAPTER SUMMARY
Table 4-1 summarizes the findings of 1,2-dichloroethylene.
Table 4-1. 1,2-Dichloroethylene Summary
Uses
Production
Releases
Properties/Fate
Media Levels
General Population
Exposure
Special Population
Exposures
Estimates
Many solvent applications
No recent information was identified
44.8 x 103 Ibs/year to air (>99% of total
environmental releases)
Volatile; insoluble in water; relatively stable
in air; flammable; significant
bioconcentration not expected
Air: <0. 545-14. 16 |ig/m3
Ambient air: 0.202 j^g/m3
Surface water: ND- 1,370 ppb
Groundwater: 0.25-0.28 ppb (average value)
Drinking water: trace-64 ppb
Inhalation: 1 to 6 ug/d
215 workers are potentially exposed
Support
Well documented
TPJ (U.S. EPA, 1996) data
Well documented
ATSDR(1996a)
161 data points, from EPA National
Ambient Database
ATSDR(1996a)
Data from early 1980s
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5.0 CIS-1,2-DICHLOROETHYLENE
5.1 CHEMICAL AND PHYSICAL PROPERTIES
The information/data presented in this section and the supporting references were
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).
5.1.1 Nomenclature
CAS No.: 156-59-2
Synonyms: 1,2-cis-dichloroethene; cis-dichloroethylene; ethene, 1,2-dichloro-,
ethyl ene; 1,2-dichloro-
Trade Names: Acetalyne dichloride
5.1.2 Formula and Molecular Weight
Structural Formula: C2H2C12
Molecular Weight: 96.95
5.1.3 Chemical and Physical Properties
Description: Liquid (Merck Index, 11th Ed., 1989); colorless (Tox & Hazard
Indus Chem Safety manual, 1982); Sweetish (Ullmann's Encyc
Indust Chem, 5th Ed., Vol Al, 1985-present).
Boiling Point: 60.3°C @ 760 mm Hg (CRC Handbook Chem & Physics, 75th
Ed., 1994-1995).
Melting Point: -80.5°C (CRC Handbook Chem & Physics, 75th Ed., 1994-1995).
Density: 1.2837 @ 20°C/4°C (CRC Handbook Chem & Physics, 75th Ed.,
1994-1995).
Spectroscopy Data: Index of refraction: 1.4490 20°C/D; maximum absorption (vapor):
greater than 200 nm (CRC Handbook Chem & Physics, 75th Ed.,
1994-1995). Sadtler reference number: 3645 (IR, Prism) (Weast,
1979). Refractive index: 1.4519 @ 15°C (Flick. Indust Solvents
Handbook, 1985). Mass: 203 (Atlas of Mass Spectral Data)
(Weast, 1985).
Solubility: Water solubility = 0.35 g/100 g @ 25°C (Kirk-Othmer, 4th Ed.,
Vol. 1, 1991-present). Soluble in alcohol, acetone, ether, benzene,
and chloroform (Weast. Hdbk Chem & Phys, 67th Ed., 1986-87).
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Volatility: Vapor Pressure: 273 mm Hg @ 30°C.
Vapor Density: 3.54 g/1 (at bp, 760 mm Hg) (Flick. Indust Solvents
Hdbk, 1985).
Stability: Decomposes slowly on exposure to air, light, and moisture.
Reactivity: May release explosive chloroacetylene by the contact with copper
or copper alloys (1,2-dichloroethylene (ITU. Tox & Hazard Indus
Chem Safety Manual, 1988). Reacts with strong oxidizers (1,2-
dichloroethylene (Sittig. Handbook Toxic Hazard Chem &
Carcinog, 2nd Ed., 1985).
Octanol/Water
Partition Coefficient: log Kow = 1.86 (Hansch. Log P Database, 1987)
5.1.4 Technical Products and Impurities
No data were identified.
5.2 PRODUCTION AND USE
The information/data presented in this section and the supporting references were
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).
5.2.1 Production
The U.S. production in 1977 was at least 5.0 x 108 g (captive production) (SRI). More
recent production data were unavailable. No data were identified for import and export volumes.
5.2.2 Uses
Cis-l,2-dichloroethylene is used as a solvent (isomeric mixture) for perfumes, dyes, and
lacquers; solvent (as mixture) for thermoplastics, fats, and phenols; solvent (as mixture) for
camphor and natural rubber; chemical intermediate (as isomeric mixture) for chlorinated
compound; and an agent in retarding fermentation (SRI). It is also used as a solvent in waxes,
resins, and acetylcellulose and used in the extraction of rubber, as a refrigerant, in the
manufacture of pharmaceuticals and artificial pearls and in the extraction of oils and fats from
fish and meat (Sittig. Handbook Toxic Hazard Chem & Carcinog, 2nd Ed., 1985).
Although cis- and trans-isomers of 1,2-dichloroethylene have had use as solvents and
chemical intermediates, neither isomer has developed wide industrial usage in the U.S., partly
because of their flammability (Patty. Indus Hyg & Tox, 3rd Ed., 1981-82). 1,2-dichloroethylenes
obtained as byproducts are used as feed stock for the synthesis of tri- and perchloroethylene
(Ullmann'sEncyc. Indust. Chem., 5th Ed., Vol la, 1985-present).
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In applications where dichloroethylenes could be used as solvents and for low
temperature extraction processes, they have been replaced by methylene chloride (Ullmann's
Encyc Indust Chem, 5th Ed., Vol Al, 1985-present).
5.2.3 Disposal
1,2-dichloroethylene may be disposed of by atomizing in a suitable combustion chamber
equipped with an appropriate effluent gas cleaning device (NIOSH/OSHA. Occupat Health
Guide Chem Hazards, 1981). Incineration is a disposal method, preferably after mixing with
another combustible fuel. Care must be exercised to assure complete combustion to prevent the
formation of phosgene. An acid scrubber is necessary to remove the halo acids produced (Sittig.
Handbook Toxic Hazard Chem & Carcinog, 2nd Ed, 1985). This compound should be
susceptible to removal from wastewater by air stripping (USEPA/ORD. 1980. Innovative and
Alternative Technology Assessment Manual).
At the time of review, criteria for land treatment or burial (sanitary landfill) disposal
practices are subject to significant revision. Prior to implementing land disposal of waste residue
(Including waste sludge) consult with environmental regulatory agencies for guidance on
acceptable disposal practices (HSDB Scientific Review Panel; HSDB, 1996).
5.3 POTENTIAL FOR HUMAN EXPOSURE
5.3.1 Natural Occurrence
Cis-l,2-dichloroethylene is not known to occur naturally.
5.3.2 Occupational
Occupational exposure to cis-l,2-dichloroethylene is expected to be through dermal
contact with the vapor and liquids and through inhalation of contaminated air at the work place
(HSDB, 1996).
5.3.3 Environmental
5.3.3.1 Environmental Releases
Cis-l,2-dichloroethylene may be released to the environment in emissions and
wastewater during its production and use as a solvent and extract (HSDB, 1996). The cis isomer
is apparently more commonly found than the trans isomer, but is usually mistakenly listed as the
trans isomer. The Michigan Department of Health has reported that it has the capability of
distinguishing between the two isomers and where concentrations are high, they occasionally find
traces of the trans isomer (HSDB, 1996). Under aerobic conditions that may exist in landfills or
sediments, 1,2-dichloroethylenes may be present as breakdown products from reduction
dehalogenation of trichloroethylene and tetrachloroethylene (HSDB, 1996).
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5.3.3.2 Monitored Environmental Media Levels
According to HSDB (1996), an assessment of the sources of the cis-l,2-dichloroethylene
is complicated because the cis isomer was a priority pollutant, unlike the trans isomer. These
isomers cannot be differentiated using the EPA standard method analysis. Therefore, monitoring
reports have erroneously listed the trans isomer when the cis isomer is present (HSDB, 1996).
(See Section 4.0 (1,2-Dichloroethylene) for more information on environmental levels.)
Air: For urban/suburban areas in the U.S., reported levels for 669 sites/samples were 68
ppt (median values) and 3,500 ppt (maximum value). Source areas (101 sites/samples) reported
levels were 300 ppt (median) and 6,700 ppt (maximum value) (HSDB, 1996).
Water: Cis-l,2-dichloroethylene was found in Miami drinking water at 16 ppb,
Cincinnati and Philadelphia at 0.1 ppb, but was not found in 7 other drinking waters surveyed
(HSDB, 1996). Raw water from a well in Wisconsin contained 83.3 ppb of this chemical. The
Biscayne Aquifer (near the Miami inactive drum recycling hazardous waste site) that supplies
drinking water to Dade County, Florida, contained 0-26 ppb. Shallow groundwater near the site
had reported levels of 839 and 13.3-17.9 ppb (HSDB, 1996).
Other Media: Data were not available for levels in food, plants, fish, animals, and milk.
5.3.3.3 Environmental Fate and Transport
5.3.3.3.1 Summary
The summary is based on the data presented in the subsequent fate and transport
subsections.
Fate in Terrestrial Environments: The dominant fate of 1,2-dichloroethylene released
to surface soils is volatilization. Some 1,2-dichloroethylene may leach downward in the soil
column because of the high water solubility and low Koc values of the two isomers. Also, 1,2-
dichloroethylene is formed under anaerobic conditions in soil, groundwater, and sediments as a
breakdown product from microbial reductive dehalogenation of the common industrial solvents
trichloroethylene, tetrachloroethylene, and 1,1,2,2,-tetrachloroethane. The fate of 1,2-
dichloroethylene in subsurface soils and groundwater is slow anaerobic degradation with the
formation of vinyl chloride as a degradation product.
Fate in the Atmosphere: In the atmosphere, 1,2-dichloroethylene is expected to be
present in the vapor phase rather than sorbed to particulate matter. Removal by scavenging
during wet precipitation is expected because of the high solubility of the two isomers. The
predominant degradation process affecting both isomers is photo-oxidation by hydroxyl radicals.
Predicted half-lives for this reaction is 8 days for the cis- isomers.
Fate in Aquatic Environments: The dominant fate of 1,2-dichloroethylene released to
surface waters is volatilization (predicted half-life of 3 hours). Bioconcentration and sorption to
sediments and suspended solids are not expected to be significant transport/partitioning
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processes. Although bio-degradation is not expected to be a significant degradation process, any
1,2-dichloroethylene that reaches the sediment will undergo slow anaerobic biodegradation.
5.3.3.3.2 Transport and Partitioning
Soil Adsorption/Mobility: The relatively low predicted soil adsorption coefficients (Koc)
for cis-1,2-dichloroethylene of 36 indicate that adsorption of the cis-1,2-dichloroethylene isomer
to soil, sediment, and suspended solids is not a significant fate process. As a consequence, these
isomers should show high mobility in soil (HSDB, 1996; Howard, 1993).
Volatilization: The dominant removal mechanism for the dichloroethylene isomers in
surface waters is volatilization. The Henry's Law constants for cis-dichloroethylene is 0.00408.
Based on this value, the estimated half-life for volatilization of cis-dichloroethylene from a
model river 1 m deep with a 1 m/sec current and a 3 m/sec wind speed is 3.1 hours. Similarly,
the volatilization half-life from aim deep body of water predicted from laboratory volatilization
studies is 5.0 hours. Because of its high vapor pressures, this isomer is also expected to readily
volatilize from soil surfaces and also from suspended paniculate matter in the atmosphere
(HSDB, 1996; Howard, 1993).
Bioconcentration: Bioconcentration factors of 15 is predicted for cis-dichloroethylene,
based on its respective octanol/water partition coefficient. Therefore, bioconcentration in aquatic
organisms should not be significant and there is little potential for biomagnification in the food
chain (HSDB, 1996; Howard, 1993).
5.3.3.3.3 Transformation and Degradation Processes
Biodegradation: The results of most aerobic biodegradation studies indicate that 1,2-
dichloroethylene is recalcitrant to aerobic degradation in soil and water (i.e., half-lives on the
order of months); however, one study reported half-lives on the order of days to weeks. Several
studies have demonstrated that both isomers will undergo slow anaerobic biodegradation in soils
and sediments with half-lives on the order of months or longer. Vinyl chloride is a degradation
product (HSDB, 1996; Howard, 1993; Howard et al., 1991).
Photodegradation: In the atmosphere, cis-1,2-dichloroethylene reacts with
photochemically produced hydroxyl radicals resulting in half-life of 8 days. The only product
positive identified from this reaction is formyl chloride. Photo-oxidation through reaction with
ozone is much slower, on the order of months. Because cis-l,2-dichloroethylene absorb only a
small amount of UV light in the environmentally significant range, direct photolysis is an
insignificant fate process (HSDB, 1996; Howard, 1993; Howard et al., 1991).
Hydrolysis: This isomer of 1,2-dichloroethylene contain no hydrolyzable groups
(Howard et al., 1991)
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5.4 HUMAN EXPOSURE AND POPULATION ESTIMATES
5.4.1 General U.S. Population
The general population is exposed to cis-l,2-dichloroethylene in urban air and from
contaminated drinking water from groundwater sources. For the average daily intake, HSDB
(1996) has reported the following: air intake, assume a concentration of 68 ppt (5.4 jig); water
intake, assume water concentration from contaminated sources of 0.23-2.7 ppb (0.5-5.4 jig) when
drinking water is contaminated (HSDB, 1996).
5.4.2 Occupational Exposure
Occupational exposure to cis-l,2-dichloroethylene is expected to be through dermal
contact with the vapor and liquids and through inhalation of contaminated air at the work place
(HSDB, 1996). Data for occupational exposures and exposed population estimates were not
found.
5.4.3 Consumer Exposure
Data for consumer exposures were not found.
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6.0 TRANS-1,2-DICHLOROETHYLENE
6.1 CHEMICAL AND PHYSICAL PROPERTIES
The information/data presented in this section and the supporting references were
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).
6.1.1 Nomenclature
CAS No.: 156-60-5
Synonyms: Ethylene, 1,2-dichloro-; sym-dichloroethylene
Trade Names: No data
6.1.2 Formula and Molecular Weight
Structural Formula: C2H2C12
Molecular Weight: 96.95
6.1.3 Chemical and Physical Properties
Description: Colorless, light liquid; sweetish odor (Ullmann's Encyc Indust
Chem, 5th Ed., Vol Al, 1985-present).
Boiling Point: 48.0-48.5°C @ 760 mm Hg (Flick. Indust Solvents Hdbk, 1985).
Melting Point: -50°C (Flick. Indust Solvents Hdbk, 1985).
Density: 1.2565 @ 20°C/4°C (CRC Handbook Chem & Physics, 75th Ed,
1994-1995).
Spectroscopy Data: Refractive index: 1.4490 @ 15°C/D (Flick. Indust Solvents Hdbk,
1985), IR: 3646 (Sadtler Research Laboratories Prism Collection);
NMR: 6742 (Sadtler Research Laboratories Spectral Collection);
MASS: 203 (Atlas of Mass Spectral Data) (Weast, 1985).
Solubility: Soluble in alcohol, ether, acetone, benzene, and chloroform
(Weast, 1986-97). Water solubility: 0.63 g/100 g @ 25°C (Flick.
Indust Solvents Hdbk, 1985).
Volatility: Vapor Pressure: 395 mm Hg at 30°C (Flick. Indust Solvents Hdbk,
1985).
Vapor Density: 3.67 g/1 at (bp at 760 mm Hg) (Flick. Indust
Solvents Hdbk, 1985).
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Stability: Gradually decomposed by air, light, and moisture, forming HC1
(HSDB Scientific Review Panel; HSDB, 1996); potential phosgene
formation (Merck Index, 10th Ed., 1983).
Reactivity: May release explosive chloroacetylene by the contact with copper
or copper alloys (1,2-dichloroethylene) (ITII. Tox & Hazard Indus
Chem Safety Manual, 1988). Reacts with strong oxidizers (Sittig.
Handbook Toxic Hazard Chem & Carcinog, 2nd Ed., 1985).
Incompatible with alkalies, difluoromethylene dihypofluorite, and
nitrogen tetraoxide (Sax. Danger Props Indus Mater, 6th Ed.,
1984).
Octanol/Water
Partition Coefficient: log Kow = 2.06 (Hansch. Log P Database, 1987).
6.1.4 Technical Products and Impurities
No data were identified.
6.2 PRODUCTION AND USE
The information/data presented in this section and the supporting references were
obtained from a retrieval from the Hazardous Substances Data Bank during September 1996.
6.2.1 Production
No data concerning U.S. production, import, or export volumes were identified.
6.2.2 Uses
Trans-1,2-dichloroethylene is more widely used in industry than either the cis isomer or
the commercial mixture (HSDB, 1996). It is used as a solvent for waxes, resins, and
acetylcellulose. It is also used in the extraction of rubber, as a refrigerant, in the manufacture of
Pharmaceuticals and artificial pearls and in the extraction of oils and fats from fish and meat
(Sittig. Handbook Toxic Hazard Chem & Carcinog, 2nd Ed., 1985). 1,2-dichloroethylenes
obtained as byproducts are used as feed stock for the synthesis of tri- and perchloroethylene. In
applications where dichloroethylenes could be used as solvents and for low temperature
extraction processes, they have been replaced by methylene chloride (Ullmann's Encyc Indust
Chem, 5th Ed., Vol. Al, 1985-present). Although this chemical has had use as a solvent and
chemical intermediate, it has not developed wide industrial usage in the U.S., partly because of
its flammability (Patty. Indus Hyg and Tox, 3rd Ed., Vol. 2A, 1981-82).
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6.2.3 Disposal
A method of disposal is incineration, preferably after mixing with another combustible
fuel. Care must be exercised to assure complete combustion to prevent the formation of
phosgene. An acid scrubber is necessary to remove the halo acids produced (Sittig. Handbook
Toxic Hazard Chem & Carcinog, 2nd Ed., 1985). Trans-1,2-dichloroethylene is a potential
candidate for rotary kiln incineration at a temperature range of 820 to 1,600°C and residence
times of seconds for liquids and gases and hours for solids. It is also a potential candidate for
fluidized bed incineration at a temperature range of 450 to 980°C and residence times of seconds
for liquids and gases, and longer for solids and a potential candidate for liquid injection
incineration at a temperature range of 650 to 1,600°C and a residence time of 0.1 to 2 seconds
(USEPA. 1981. Engineering Handbook for Hazardous Waste Incineration). This compound
should be susceptible to removal from wastewater by air stripping (USEPA/ORD. 1980.
Innovative and Alternative Technology Assessment Manual).
At the time of review, criteria for land treatment or burial (sanitary landfill) disposal
practices are subject to significant revision. Prior to implementing land disposal of waste residue
(Including waste sludge) consult with environmental regulatory agencies for guidance on
acceptable disposal practices (HSDB Scientific Review Panel, HSDB, 1996).
6.3 POTENTIAL FOR HUMAN EXPOSURE
6.3.1 Natural Occurrence
Trans-1,2-dichloroethylene is not known to occur naturally.
6.3.2 Occupational
Potential occupational exposures exist in production and manufacturing facilities from
the use of trans-1,2-dichloroethylene as a solvent and extractant.
6.3.3 Environmental
6.3.3.1 Environmental Releases
Trans-1,2-dichloroethylene may be released to the environment in air emissions and
wastewater during its production and use. Dichloroethylenes can be found as breakdown
products from the reduction dehalogenation of common industrial solvents such as
trichloroethylene, tetrachloroethylene, and 1,1,2,2-tetrachloroethane under aerobic high organic
mix conditions, that may exist in landfills, aquifers, or sediment. The cis isomer is the isomer
found most. However, it mistakenly reported as the trans isomer because EPA standard methods
analytical procedures do not distinguish between isomers (HSDB, 1996). See Section 4.0 (1,2-
Dichloroethylene) for more information on environmental levels.
Air: Trans-1,2-dichloroethylene has been identified in ambient air near production and
manufacturing facilities from its use.
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Water: Trans-1,2-dichloroethylene has been detected in drinking water, surface water,
and groundwater.
Other Media: Trans-1,2-dichloroethylene has been identified in the effluent of many
manufacturing facilities, POTW effluents (and sludges), urban runoff, and sediment and soil
samples (HSDB, 1996).
6.3.3.2 Monitored Environmental Media Levels
Air: The atmospheric concentration near source areas in Edison, New Jersey, was 930 ppt
(HSDB, 1996).
Water: Trans-1,2-dichloroethylene was found in drinking water in Miami at 1 PPB; in
private wells in Illinois at nondetected to 64 ppb with a median of 8 ppb (HSDB, 1996). It was
found in a groundwater plume of predominantly trichloroethylene that was believed to originate
from an old industrial source. In Tacoma, Washington, two utility production wells had levels of
200 ppb trans-l,2-dichloroethylene. Groundwater monitoring wells (789 wells) near a
degreasing plant in Connecticut contained levels of this chemical ranging from 1.2 - 320.9 ppb
(HSDB, 1996).
Other Media: In an EPA survey of wastewater from 4,000 industrial and publicly owned
treatment works, the highest effluent concentration among several industries was for iron and
steel manufacturing at 3,013 ppb, with a median contamination of 2,265.9 ppb. Median
concentrations in the effluents of other industries were: organics and plastics (14.6 ppb);
inorganic chemicals (3.9 ppb); rubber processing (19.0 ppb); auto and other laundries (60.6 ppb);
explosives (3.9 ppb); electronics (140.7 ppb); mechanical products (13.7 ppb); transportation
equipment (29.3 ppb); POTWs (16.3 ppb) (Shackelford et al., Analyt Chem Acta, Vol. 146,
1983; HSDB, 1996). In another survey of industrial occurrences, wastewater discharges had the
following mean concentrations: metal finishing (260 ppb); photographic equipment (2,200 ppb
maximum concentration); nonferrous metal manufacturing (75 ppb); rubber processing (150
ppb).
6.3.3.3 Environmental Fate and Transport
6.3.3.3.1 Summary
The summary is based on the data presented in the subsequent fate and transport
subsections.
Fate in Terrestrial Environments: The dominant fate of 1,2-dichloroethylene released
to surface soils is volatilization. Some 1,2-dichloroethylene may leach downward in the soil
column because of the high water solubility and low Koc values of the two isomers. Also, 1,2-
dichloroethylene is formed under anaerobic conditions in soil, groundwater, and sediments as a
breakdown product from microbial reductive dehalogenation of the common industrial solvents
trichloroethylene, tetrachloroethylene, and 1,1,2,2,-tetrachloroethane. The fate of 1,2-
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dichloroethylene in subsurface soils and groundwater is slow anaerobic degradation with the
formation of vinyl chloride as a degradation product.
Fate in the Atmosphere: In the atmosphere, 1,2-dichloroethylene is expected to be
present in the vapor phase rather than sorbed to particulate matter. Removal by scavenging
during wet precipitation is expected because of the high solubility of the two isomers. The
predominant degradation process affecting both isomers is photo-oxidation by hydroxyl radicals.
Predicted half-lives for this reaction is 3.6 days for the trans- isomers.
Fate in Aquatic Environments: The dominant fate of 1,2-dichloroethylene released to
surface waters is volatilization (predicted half-life of 3 hours). Bioconcentration and sorption to
sediments and suspended solids are not expected to be significant transport/partitioning
processes. Although biodegradation is not expected to be a significant degradation process, any
1,2-dichloroethylene that reaches the sediment will undergo slow anaerobic biodegradation.
6.3.3.3.2 Transport and Partitioning
Soil Adsorption/Mobility: The relatively low predicted soil adsorption coefficients (Koc)
for trans-1,2-dichloroethylene, 49, indicate that adsorption of this 1,2-dichloroethylene isomer to
soil, sediment, and suspended solids is not a significant fate process. As a consequence, this
isomer should show high mobility in soil (HSDB, 1996; Howard, 1993).
Volatilization: The dominant removal mechanism for the dichloroethylene isomers in
surface waters is volatilization. The Henry's Law constants for trans-dichloroethylene is 0.00938.
Based on this value, the estimated half-life for volatilization of trans-dichloroethylene from a
model river 1 m deep with a 1 m/sec current and a 3 m/sec wind speed is 3.0 hours. Similarly,
the volatilization half-life from aim deep body of water predicted from laboratory volatilization
studies is 6.2 hours. Because of its high vapor pressure, this isomer is also expected to readily
volatilize from soil surfaces and also from suspended particulate matter in the atmosphere
(HSDB, 1996; Howard, 1993).
Bioconcentration: Bioconcentration factors of 15 and 22 are predicted for cis- and trans-
dichloroethylene, respectively, based on their respective octanol/water partition coefficients.
Therefore, bioconcentration in aquatic organisms should not be significant and there is little
potential for biomagnification in the food chain (HSDB, 1996; Howard, 1993).
6.3.3.3.3 Transformation and Degradation Processes
Biodegradation: The results of most aerobic biodegradation studies indicate that 1,2-
dichloroethylene is recalcitrant to aerobic degradation in soil and water (i.e., half-lives on the
order of months); however, one study reported half-lives on the order of days to weeks. Several
studies have demonstrated that both isomers will undergo slow anaerobic biodegradation in soils
and sediments with half-lives on the order of months or longer. Vinyl chloride is a degradation
product (HSDB, 1996; Howard, 1993; Howard et al., 1991).
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Photodegradation: In the atmosphere, trans- 1,2-dichloroethylene react with
photochemically produced hydroxyl radicals resulting in a half-life of 3.6 days. The only product
positive identified from this reaction is formyl chloride. Photo-oxidation through reaction with
ozone is much slower, on the order of months. Because trans-1,2-dichloroethylene absorb only a
small amount of UV light in the environmentally significant range, direct photolysis is an
insignificant fate process (HSDB, 1996; Howard, 1993; Howard et al., 1991).
Hydrolysis: Trans-1,2-dichloroethylene contains no hydrolyzable groups (Howard et al.,
1991)
6.4 HUMAN EXPOSURE AND POPULATION ESTIMATES
6.4.1 General U.S. Population
The general population is exposed to trans-1,2-dichloroethylene in urban air and
contaminated drinking water from ground water sources.
6.4.2 Occupational Exposure
Occupational exposure will be through dermal contact with the vapor and liquid or
through inhalation. Data for occupational exposures and exposed population estimates were not
found.
6.4.3 Consumer Exposure
Data for consumer exposures were not found.
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7.0 1,1,1,2-TETRACHLOROETHANE
7.1 CHEMICAL AND PHYSICAL PROPERTIES
The information/data presented in this section and the supporting references were
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).
7.1.1 Nomenclature
CAS No.: 630-20-6
Synonyms: Ethane, 1,1,1,2-tetrachloro-
Trade Names: NCI-C52459
7.1.2 Formula and Molecular Weight
Structural Formula: C2H2C14
Molecular Weight: 167.85
7.1.3 Chemical and Physical Properties
Description: Yellowish-red liquid (NIOSH Pocket Guide Chem Haz, 1994).
Boiling Point: 130.5°C @ 760 mm Hg (CRC Handbook Chem & Physics, 75th
Ed., 1994-1995).
Melting Point: -70.2°C (CRC Handbook Chem & Physics, 75th Ed., 1994-1995).
Density: 1.4506 @ 20°C/4°C (CRC Handbook Chem & Physics, 75th Ed.,
1994-1995).
Spectroscopy Data: Index of Refraction: 1.4821 @ 20°C/D (Weast, 1986-87); Mass:
1074 (Atlas of Mass Spectral Data) (Weast, 1985).
Solubility: Water solubility is 1.1 x 103 mg/1 @ 25°C (McKay and Shiu, 1981;
J. Phys. Chem. Ref Data, Vol. 19). Soluble in alcohol, ether,
acetone, benzene, chloroform (Weast, 1986-87).
Volatility: Vapor Pressure - 14 Torr at 25°C (Willing, WL. 1977. Environ Sci
Technol, Vol. 11).
Vapor Density - No data.
Stability: Decomposes when heated and emits toxic fumes of chlorine (Sax,
6th Ed., 1984); when in contact with flame, incandescent material,
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or red hot metal surfaces, it decomposes to form hydrochloric acid,
carbon monoxide, and carbon dioxide (Encyc. Occupat. Health and
Safety, 1983).
Reactivity: Mixtures of sodium-potassium alloy and bromoform,
tetrachloroethane, or pentachloroethane can explode on standing at
room temperature. They are especially sensitive to impact (NFPA.
1986. Fire Protect Guide Hazard Matls, 9th Ed.) Reacts with
dinitrogen tetraoxide; potassium hydroxide nitrogen tetroxide; 2,4-
dinitrophenyl disulfide (NIOSH Pocket Guide Chem Haz, 1994).
Octanol/Water
Partition Coefficient: Log Kow = 2.66 (IARC Monographs, 1972-present)
7.1.4 Technical Products and Impurities
1,1,1,2-tetrachloroethane is available at 99% purity and is used for a laboratory standard
for selected EPA methods (The Aldrich Catalog/Handbook of Fine Chemicals, 1994-95). It is
not available in commercial quantities.
7.2 PRODUCTION AND USE
The information/data presented in this section and the supporting references were
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).
7.2.1 Production
As of 1982, this chemical was not produced commercially in USA; no data are available
for other years. This chemical is not produced on an industrial scale and is mainly the byproduct
from the production of chlorinated ethanes. No data are available concerning import and export
volumes.
7.2.2 Uses
1,1,1,2-tetrachloroethane is used as a solvent in cleaning, degreasing, and extraction
processes; in manufacture of insecticides, herbicides, soil fumigants, bleaches, paints and
varnishes and as a laboratory reagent (NRC. 1977. Drinking Water & Health; IARC
Monograph, V.41, 1986). 1,1,1,2-tetrachloroethane is used primarily as a feedstock for the
production of solvents such as trichloroethylene and tetrachloroethylene (Kirk-Othmer. 1991-
present. Encyc Chem Tech, 4th Ed., Vol 1).
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7.2.3 Disposal
1,1,1,2-tetrachloroethane is a potential candidate for fluidized bed incineration at a
temperature range of 450 to 980°C and residence times of seconds for liquids and gases and
longer for solids; for rotary kiln incineration at a temperature range of 820 to 1,600°C and
residence times of seconds for liquids and gases and hours for solids; and for liquid injection
incineration at a temperature range of 650 to 1,600°C and a residence time of 0.1 to 2 seconds
(USEPA. 1981. Engineering Handbook for Hazardous Waste Incineration. EPA 68-03-3025).
Incineration is a method of disposal, preferably after mixing with another combustible fuel. Care
must be exercised to assure complete combustion to prevent the formation of phosgene. An acid
scrubber is necessary to remove the halo acids produced. Recommendable methods are
incineration and evaporation. Not recommendable method: discharge to sewer.
At the time of review, criteria for land treatment or burial (sanitary landfill) disposal
practices are subject to significant revision. Prior to implementing land disposal of waste residue
(including waste sludge), consult with environmental regulatory agencies for guidance on
acceptable disposal practices (HSDB Scientific Review Panel; HSDB, 1996).
7.3 POTENTIAL FOR HUMAN EXPOSURE
7.3.1 Natural Occurrence
Available data do not indicate that 1,1,1,2-tetrachloroethane occurs naturally.
7.3.2 Occupational
1,1,1,2-tetrachloroethane is not produced on an industrial scale but is formed as an
incidental byproduct. Potential occupational exposure would occur from exposure to air
emissions or contact with the vapor or liquid in the workplace.
7.3.3 Environmental
7.3.3.1 Environmental Releases
According to available data, it appears that 1,1,1,2-tetrachloroethane is currently not
produced in the U.S. However, since the chemical may be formed incidentally during the
manufacture of other chlorinated ethanes, it may be released into the environment as air
emissions or in wastewater (HSDB, 1996). It has not been confirmed if this chemical is currently
used in the U.S. However, if used, environmental releases as a result of use would be expected.
7.3.3.2 Monitored Environmental Media Levels
Air: Field studies were conducted in Arizona and California to better characterize the
abundance of selected chemicals in the atmosphere. Average daily dosages from exposure to
haloethane, including 1,1,1,2-tetrachloroethane, was determined to be 142 |ig/day (Singh, H.B. et
al., 1981; Atmos. Environ. Vol. 15, No. 4; HSDB, 1996). 1,1,1,2-tetrachloroethane was not
79
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detected in two rural/remote sites in the U.S. For 602 urban/suburban sites in the U.S., a median
level of 2.2 ppt and a maximum level of 63 ppt were found. In source areas, 43 sites/samples in
the U.S., the mean concentration was 0.071 ppt and the maximum level 3.1 ppt. However,
1,1,1,2-tetrachloroethane was not detected in over 75 percent of the samples (Brodzinsky and
Singh, SRI Contract 68-02-34; Class and Ballschmiter, 1986, Chemosphere, Vol. 15; HSDB,
1996).
Water: In the U.S. Groundwater Supply Survey, 1,1,1,2-tetrachloroethane was not
detected (detection limit 0.2 ppb) in the drinking water of 945 supplies where groundwater was
the source (Westrick et al., 1984; J. Amer. Water Works Assoc., Vol. 76; HSDB, 1996).
Other Media: Wastewater was analyzed in a survey conducted by the EPA of 4,000
industrial and publicly owned treatment works. 1,1,1,2-tetrachloroethane was identified in the
discharges from several industrial categories. The median concentrations reported as follows:
organics and plastic (27.4 ppb); inorganic chemicals (14.8 ppb); and electronics (272.6 ppb)
(Shackelford, W.M. et al., 1983, Analyt. Chem. Acta., Vol. 146; HSDB, 1996).
7.3.3.3 Environmental Fate and Transport
7.3.3.3.1 Summary
The summary is based on the data presented in the subsequent fate and transport
subsections.
Fate in Terrestrial Environments: The dominant fate of 1,1,1,2-tetrachloroethane
released to surface soils is volatilization. Because of its moderate mobility in soils,
tetrachloroethylene introduced into soil (e.g., landfills) has the potential to migrate through the
soil into groundwater.
Fate in the Atmosphere: In the atmosphere, 1,1,1,2-tetrachloroethane is expected to be
present primarily in the vapor phase rather than sorbed to particulates because of its moderate
vapor pressure. Removal by scavenging during wet precipitation is expected because of the
moderate solubility of 1,1,1,2-tetrachloroethane in water (1,100 mg/L). The maj or degradation
process affecting vapor phase 1,1,1,2-tetrachloroethane is photo-oxidation by hydroxyl radicals
and the chlorine radicals formed by the hydroxyl radical reaction (half-life on the order of years).
Due to its persistence, 1,1,1,2-tetrachloroethane will disperse over long distances and slowly
diffuse into the stratosphere where it would be rapidly degraded.
Fate in Aquatic Environments: The dominant fate of 1,1,1,2-tetrachloroethane released
to surface waters is volatilization (predicted half-life of hours). Bioconcentration and sorption to
sediments and suspended solids are not expected to be significant transport/partitioning
processes.
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7.3.3.3.2 Transport and Partitioning
Soil Adsorption/Mobility: AKocof 93 is predicted for 1,1,1,2-tetrachloroethane based
on its measured water solubility. An experimentally determined Koc for 1,1,1,2-tetrachloroethane
is reported to be 399. Based on the predicted and measured Kocs, 1,1,1,2-tetrachloroethane is
expected to exhibit moderate mobility and may leach slowly to the groundwater particularly in
soils with low organic content (HSDB, 1996).
Volatilization: The dominant removal mechanism for 1,1,1,2-tetrachloroethane in
surface waters is volatilization. The half-life will depend on wind and mixing conditions and is
estimated to range from 4 to 11 hours in rivers, lakes, and ponds based on laboratory
experiments. Because of its moderate vapor pressure (14 torr at 25 degrees C) and relatively low
soil adsorption coefficient (Koc of 93 to 399), 1,1,1,2-tetrachloroethane is expected to volatilize
from dry soil surfaces and also from suspended particulate matter in the atmosphere (HSDB,
1996).
Bioconcentration: No experimental data are available on the bioconcentration of 1,1,1,2-
tetrachloroethane. A bioconcentration factor of 12 is predicted for 1,1,1,2-tetrachloroethane
based on its measured water solubility of 1,100 mg/L. Actual BCFs measured in fish studies are
less than 10 for structurally similar halogenated aliphatic compounds. Therefore,
bioconcentration in aquatic organisms should not be significant and there is little potential for
biomagnification in the food chain (HSDB, 1996).
7.3.3.3.3 Transformation and Degradation Processes
Biodegradation: Little information is available on the biodegradability of 1,1,1,2-
tetrachloroethane. Based on the results of a river die-away test for 1,1,1,2-tetrachloroethane and
several studies examining the biodegradability of 1,1,1-trichloroethane, 1,1,1,2-tetrachloroethane
is estimated to undergo biodegradation at a slow rate. The estimated half-lives are one to six
months under aerobic conditions and 4 to six months under anaerobic conditions (Howard et al.,
1991).
Photodegradation: Based upon an estimated rate constant for the vapor phase photo-
oxidation reaction with photochemically produced hydroxyl radicals, the half-life of 1,1,1,2-
tetrachloroethane in the atmosphere is 550 days. No data are readily available on the photolysis
of 1,1,1,2-tetrachloroethane (HSDB, 1996).
Hydrolysis: Hydrolysis of 1,1,1,2-tetrachloroethane is not significant at environmental
temperatures and pHs; the half-life for this process (at 25 C, pH 7) is 46.8 years (HSDB, 1996).
7.4 HUMAN EXPOSURE AND POPULATION ESTIMATES
7.4.1 General U.S. Population
Potential exposure, if any, to the general population would probably be through inhalation
of ambient air contaminated with 1,1,1,2-tetrachloroethane (HSDB, 1996).
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7.4.2 Occupational Exposure
Data are not available for the estimated occupationally exposed populations.
7.4.3 Consumer Exposure
According to Kirk-Othmer (1991), 1,1,1,2-tetrachloroethane is used primarily as a
feedstock for the production of solvents such as trichloroethylene and tetrachloroethylene
(HSDB, 1996). The IARC Monographs in 1986 have reported use in the manufacture of
products such as paints and varnishes. It has not been confirmed if this use is current or if these
products are/were consumer or industrial products (HSDB, 1996).
7.5 CHAPTER SUMMARY
Table 7-1 summarizes the findings of 1,1,1,2-tetrachloroethane.
Table 7-1. 1,1,1,2-Tetrachloroethane Summary
Uses
Production
Releases
Properties/Fate
Media Levels
General Population
Exposure
Special Population
Exposures
Estimates
Many solvent applications; chemical
intermediate
As of 1982, not produced in U.S.; no other
data are available
No available data
Volatile; water soluble; no significant
bioconcentration; moderate mobility
Air: 0.012 [ig/m3 - median value at
602 urban/suburban sites
Water: Non detect (detection limit = 0.2
ppb) in 945 groundwater supplies
No available data
No available data
Support
Recent information
Recent information
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8.0 1,1-DICHLOROETHANE
8.1 CHEMICAL AND PHYSICAL PROPERTIES
The information/data presented in this section and the supporting references were
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).
8.1.1 Nomenclature
CAS No.:
75-34-3
Synonyms: Ethane, 1,1-dichloro-; ethylidene chloride; ethylidene dichloride
Trade Names: NCI-C04535
8.1.2 Formula and Molecular Weight
Molecular Formula:
Molecular Weight:
C2H4C12
98.97
8.1.3 Chemical and Physical Properties
Description:
Boiling Point:
Melting Point:
Density:
Spectroscopy Data:
Solubility:
Volatility:
Oily liquid, chloroform-like odor, taste as of chloroform
(Merck Index, llth Ed., 1989); colorless liquid (Sax. Danger
Props Idus Mater, 6th Ed., 1984); colorless, oily liquid,
chloroform-like odor (NIOSH Pocket Guide Chem Haz, 1994);
aromatic ethereal odor (Sax. Hawley's Condensed Chem Diet,
llth Ed., 1987).
57.3°C (Merck Index, llth Ed., 1989).
-96.9°C (CRC Handbook Chem & Physics, 75th Ed., 1994-
1195).
1.175 @ 20°C/4°C (Merck Index, llth Ed., 1989).
Index of Refraction: 1.4167 @ 20°C (Merck Index, 11th Ed.,
1989); Sadtler Reference Number: 3205 (IR, prism); J118
(NMR) (Weast, 1979); Mass: 68 (National Bureau of Standards
EPA-Nffl Mass Spectra Data Base) (Weast, 1985).
0.55 g/100 ml water at 20°C; soluble in ethanol, ethyl ether
(Patty. Indus Hyg & Tox, 3rd Ed., Vol 2A, 2B, 2C, 1981-82)
Vapor Pressure: 3.44 (air = 1) (Sax. Danger Props Indus
Mater, 6th Ed., 1984).
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Vapor Density: 234 torr at 25°C (Patty. Indus Hyg & Tox, 3rd
Ed., Vol 2A, 2B, 3C, 1981-82).
Stability: No data.
Reactivity: Reacts with strong oxidizers, strong caustics (NIOSH Pocket
Guide Chem Haz, 1994).
Octanol/Water
Partition Coefficient: Log Kow = 1.9 (ITC/USEPA. Information Review #209
(Draft) Chloroethanes, 1980).
8.1.4 Technical Products and Impurities
1,1-dichloroethane is produced as reagent grade, 99.7% pure, with the following
impurities: ethyl chloride 0.02%, butylene oxide 0.08%, trichloroethylene 0.08%, ethylene
dichloride 0.01%, unknown 0.14% (expressed as volume percentage by weight of sample
(ITC/USEPA. 1980. Information Review #209).
8.2 PRODUCTION AND USE
The information/data presented in this section and the supporting references were
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).
8.2.1 Production
No information was identified for U.S. production, import, or export volumes.
8.2.2 Uses
1,1-dichloroethane is used as a solvent for plastics, oils, and fats; cleaning agent;
degreaser; in rubber cementing; as a fumigant and insecticide spray; in fabric spreading; in fire
extinguishing; and in medication: formerly used as an anesthetic (Browning. 1965. Tox &
Metab Indus Solv). It is also used as an extractant for heat-sensitive substances (NIOSH OSHA.
1981. Occupat Health Guide Chem Hazards). Other uses include as a coupling agent in
antiknock gasoline; in paint, varnish and paint removers; metal degreasing; and in ore flotation
(Verschueren. 1983. Handbook Environ Data Org Chem). 1,1 -dichloroethane is usually used as
an intermediate in the production of 1,1,1-trichloroethane by thermal chlorination or
photochlorination and in the production of vinyl chloride (Kirk-Othmer, 1991-present).
8.2.3 Disposal
Generators of waste containing this contaminant (i.e., EPA hazardous waste number
U076) must conform with USEPA regulations in storage, transportation, treatment, and disposal
of waste (40 CFR 240-280, 300-306, 702-799). 1,1-dichloroethane may be disposed of by
atomizing in a suitable combustion chamber equipped with an appropriate effluent gas cleaning
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device (NIOSH OSHA. 1981. Occupat Health Guide Chem Hazards). It is a potential candidate
for liquid injection incineration, with a temperature range of 650 to 1,600°C and a residence time
of 0.1 to 2 seconds; for rotary kiln incineration, with a temperature range of 820 to 1,600 °C and
a residence time of seconds; and for fluidized bed incineration, with a temperature range of 450
to 980°C and a residence time of seconds (USEPA. 1981. Engineering Handbook for Hazardous
Waste Incineration). The following wastewater treatment technologies have been investigated
for 1,1-dichloroethane: concentration process: stripping, solvent extraction, activated carbon,
and resin adsorption (USEPA. 1982. Management of Hazardous Waste Leachate. EPA
Contract No. 68-03-2766).
8.3 POTENTIAL FOR HUMAN EXPOSURE
8.3.1 Natural Occurrence
There are no known natural sources of 1,1-dichloroethane; however, it has been reported
that 1,1,1-trichloroethane is biodegraded to 1,1-dichloroethane in anaerobic environments such as
landfills (ATSDR, 1990).
8.3.2 Occupational
In addition to members of the general populations living near emission point sources and
hazardous waste sites, human exposure to 1,1-dichloroethane is expected to be highest among
certain occupational groups (ATSDR, 1990). These groups are workers in the chemical and
allied products industry (ATSDR, 1990).
8.3.3 Environmental
8.3.3.1 Environmental Releases
The primary disposition of 1,1-dichloroethane in the environment is the result of
production, storage, consumption, transport, and disposal from its use as chemical intermediate,
solvent, finish remover, and degreaser (ATSDR, 1990). Releases from industrial processes are
almost exclusively to the atmosphere. 1,1-dichloroethane has been detected generally at low
levels in ambient air, surface water, groundwater, drinking water, and human breath.
Concentrations are largest in environmental media near source areas (ATSDR, 1990). Another
source of this chemical in the environment is the reduction (biotic or abiotic) of 1,1,1-
trichloroethane to 1,1-dichloroethane in groundwater (HSDB, 1996).
Air: The majority (99 percent) of all releases of 1,1-dichloroethane to the environment
are emissions to the atmosphere (ATSDR, 1990). Releases from the production of 1,1,1-
trichloroethane and 1,2-dichloroethane account for approximately 52 percent and 35 percent,
respectively of these releases (ATSDR, 1990). Approximately 52,000 kg of 1,1-dichloroethane
are released to the air from POTWs (ATSDR, 1990).
Water: Releases of 1,1-dichloroethane to surface waters from industrial solvent use and
from POTWs are approximately 2,000 kg/yr (ATSDR, 1990). The largest sources of these
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releases are believed to be from its use as a cleaning solvent or chemical intermediate and from
POTWs (ATSDR, 1990). Approximately 1,000 kg/yr of 1,1-dichloroethane are released in the
effluents of POTWs (ATSDR, 1990).
Other Media: Releases to land from solvent use and POTWs were estimated at 6,000 kg
in 1978 (ATSDR, 1990). According to ATSDR (1990), approximately 4,000 kg/yr of 1,1-
dichloroethane are released to land as sludge from POTWs.
8.3.3.2 Monitored Environmental Media Levels
Air: Atmospheric levels of 1,1-dichloroethane have been detected at urban, rural, and
industrial sites across the U.S. The reported median concentration is 55 ppt (ATSDR, 1990). In
the urban/suburban parts of the U.S., reported concentrations were 61 ppt (median value) and 100
ppt (maximum values) for the analysis of 455 samples (HSDB, 1996). The concentrations in
source areas (101 samples) were 11 ppt (median value) and 1,400 ppt (maximum value) (HSDB,
1996).
Water: Data summarized from the EPA STORET data base in 1982 have shown
concentrations for 1,1-dichloroethane ranging from <10 ppb (not detected) to 1,900 ppb
(ATSDR, 1990). The highest reading was from the upper Mississippi River Basin; however, the
reported monitoring results indicated that in surface water the levels were mostly <10 ppb.
According to a study summarizing groundwater data from numerous State agencies, 18
percent of monitored drinking water wells contained 1,1-dichloroethane; the highest reported
concentration in wells was 11,300 ppb and a maximum surface concentration of 0.2 ppb
(ATSDR, 1990; HSDB, 1996). In Iowa, 127 wells from 58 public water supplies contained 1,2-
dichloroethane residues 1 to 24 ppb (HSDB, 1996).
Finished water supplies in the U.S. from groundwater sources that were tested for EPA
contaminants had a maximum concentration of 4.2 ppb; detectable levels of 1,1-dichloroethane
was found in 10.8 percent of 158 non-random samples. Groundwater samples taken from 178
hazardous waste disposal sites contained an average concentration of 0.31 ppm with a maximum
concentration of 56.1 ppm and had a frequency of 18 percent (ATSDR, 1990).
Other Media: Data for levels in soil were not found. The reported mean concentration
was 33 ppt for oysters obtained from the Mississippi River delta (HSDB, 1996). Information
were not found for ambient concentrations of 1,1-dichloroethane in soil, current disposal of
waste products containing this chemical in landfills, foods, plants, fish, or animals (HSDB, 1996;
ATSDR, 1990).
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8.3.3.3 Environmental Fate and Transport
8.3.3.3.1 Summary
The summary is based on the data presented in the subsequent fate and transport sections.
Fate in Terrestrial Environments: The dominant fate of 1,1-dichloroethane released to
surface soils is volatilization. Because of its high mobility in soils, 1,1-dichloroethane
introduced into soil (e.g., landfills) has the potential to migrate through the soil into groundwater.
Biodegradation under anaerobic conditions in soil and groundwater may occur at a relatively
slow rate (half-lives on the order of months or longer).
Fate in the Atmosphere: In the atmosphere, 1,1-dichloroethane is expected to be present
in the vapor phase rather than sorbed to particulate matter. Removal of 1,1-dichloroethane
during wet precipitation is expected because of its relatively high water solubility. 1,1-
Dichloroethane will degrade by reaction with photochemically produced hydroxyl radicals.
Because photo-oxidation is not a rapid process (predicted half-lives ranging from 10 to 100
days), considerable dispersion of 1,1-dichloroethane in the atmosphere may occur.
Fate in Aquatic Environments: The dominant fate of 1,1-dichloroethane released to
surface waters is volatilization (predicted half-life of 1 to 10 days). Bioconcentration,
biodegradation, and sorption to sediments and suspended solids are not expected to be significant
fate processes.
8.3.3.3.2 Transport and Partitioning
Soil Adsorption/Mobility: The very low predicted soil adsorption coefficients (Koc) for
1,1-dichloroethane (Koc of 43) indicates that sorption of 1,1-dichloroethane to soil, sediment, and
suspended solids is not a significant fate process. As a consequence, these isomers should show
high mobility in soil (HSDB, 1996).
Volatilization: The dominant removal mechanism for the 1,1-dichloroethane isomers in
surface waters is volatilization. The half-life will depend on wind and mixing conditions and is
estimated to range from 1 to 10 days in rivers, lakes, and ponds based on laboratory experiments.
Because of its high vapor pressure and relatively low soil adsorption coefficient, 1,1-
dichloroethane is expected to volatilize rapidly from soil surfaces and also from suspended
parti culate matter in the atmosphere (HSDB, 1996).
Bioconcentration: A bioconcentration factor of 1.3 is predicted for 1,1-dichloroethane
based on the reported water solubility of 5,500 mg/L. Therefore, bioconcentration in aquatic
organisms should not be significant and there is little potential for biomagnification in the food
chain (HSDB, 1996).
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8.3.3.3.3 Transformation and Degradation Processes
Biodegradation: The results of aerobic biodegradation studies indicate that 1,1-
dichloroethane is recalcitrant to aerobic degradation in soil and water (i.e., half-lives on the order
of months). Although no studies examining the anaerobic biodegradation of 1,1-dichloroethane
are available, the estimated half-life under anaerobic conditions has been estimated to range from
months to years (HSDB, 1996; Howard et al., 1991).
Photodegradation: Based on measured rate data for the vapor phase reaction with
hydroxyl radicals, the estimated half-life of 1,1-dichloroethane in the troposphere ranges from 10
to 100 days (HSDB, 1996; Howard et al., 1991).
Hydrolysis: No information specifically addressing the hydrolytic half-life of 1,1-
dichloroethane is available. Considering the volatility of 1,1-dichloroethane from water and the
fact that the hydrolytic half-lives of structurally similar chlorinated ethanes are on the order of
months to years, indicates that hydrolysis is not an important fate process (HSDB, 1996; Howard
etal., 1991).
8.4 HUMAN EXPOSURE AND POPULATION ESTIMATES
8.4.1 General U.S. Population
The primary route of exposure for the general population to 1,1-dichloroethane is the
inhalation of air contaminated with this chemical. An additional potential route of exposure is
ingestion of 1,1-dichloroethane contaminated drinking water. Specifically, persons near
industrial facilities and hazardous waste may be potentially exposed from inhalation of ambient
air and ingestion of drinking water (ATSDR, 1990). EPA has identified 1,1-dichloroethane in
248 of the 1,177 NPL sites; the number of sites evaluated for this chemical was not reported
(ATSDR, 1990). The frequency of these sites within the U.S. are presented in Figure 8-1.
The U.S. EPA assumed median ambient air concentration of 55 ppt and an average
inhalation rate of 20 m3/day and estimated the average inhalation exposure to 1,1-dichloroethane
from the general population to be 4 |ig/day (ATSDR, 1990).
8.4.2 Occupational Exposure
Populations potentially exposed in the workplace in the early 1980s were estimated by
NIOSH to have ranged from 715 to 1,957 workers (ATSDR, 1990). Occupational exposures are
primarily the result of the use of 1,1-dichloroethane as a chemical intermediate, solvent, and a
component of fumigant formulations (ATSDR, 1990).
8.4.3 Consumer Exposure
No data were found for consumer exposure estimates.
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FREQUENCY
1 TO 3 SITES
11 TO SO SITES
3 TO 1O SITES
OVER 2O SITES
Figure 8-1. Frequency of NPL Sites with 1,1-Dichloroethane Contamination (Source' ATSDR
1990)
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8.5 CHAPTER SUMMARY
Table 8-1 summarizes the findings of 1,1-dichloroethane.
Table 8-1. 1,1-Dichloroethane Summary
Uses
Production
Releases
Properties/Fate
Media Levels
General Population
Exposure
Special Population
Exposures
Estimates
Many solvent uses; fumigant; chemical
intermediate; degreaser
No available information
Predominantly air - 52,000 kg released to air
fromPOTWs
Volatile; slightly soluble in water; no
significant bioconcentration or
biodegradation expected
Air: urban/suburban - 0.332 |^g/m3
(median)
Water: surface water < 1 0 ppb to 1,900 ppb
Groundwater: varies
1 to 24 ppb (Iowa; 127 wells)
Primarily through air or potentially
contaminated groundwater
Air = 4 [ig/d
Chemical and allied product workers
Support
Well documented
ATSDR(1990)
455 samples
ATSDR(1990)
ATSDR(1990)
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SECTION C. METABOLITES OF TRICHLOROETHYLENE AND PARENT
COMPOUNDS
9.0 CHLORAL
9.1 CHEMICAL AND PHYSICAL PROPERTIES
The information/data presented in this section and the supporting references were
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996) and IARC
(1995).
9.1.1 Nomenclature
CAS No.:
Synonyms:
Trade Name:
75-87-6
2,2,2-trichloroacetaldehyde; acetaldehyde, trichloro-; anhydrous
chloral; trichloroacetaldehyde; trichloroethanol
Grasex
9.1.2 Formula and Molecular Weight
Structural Formula:
Molecular Weight:
C2HC13-0
147.40
9.1.3 Chemical and Physical Properties
Description:
Boiling Point:
Melting Point:
Density:
Spectroscopy Data:
Colorless, oily liquid with an irritating odor (Encyc. Occupat.
Health & Safety, 1983).
97.8°C @ 760 mm Hg (Merck Index, 10th Ed., 1983).
-57.5°C (Merck Index, 10th Ed., 1983).
1.5121 @ 20°C/4°C (Weast. Hdbk. Chem. & Phys., 67th Ed.,
1986-87).
Index of refraction: 1.45572 @ 20°C/D (Weast. Hdbk. Chem. &
Phys., 67th Ed., 1986-87); IR: 4626, IR: 4426 (Sadtler Research
Laboratories Prism Collection); IR: 6507 (Coblentz Society
Spectral Collection); UV: 5-3 (Organic Electronic Spectral
Data); Mass: 814 (Atlas of Mass Spectral Data) (Weast. CRC
Hdbk. Data Organic CPDS., Vol. I, II, 1985)
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Solubility: Highly soluble in water; soluble in alcohol, ether (Merck Index,
10th Ed., 1983); chloral hydrate is extremely soluble in water
(825 g/100 g water (Seidell, A. (1941) Solubilities of Organic
Compounds); soluble in chloroform (Condensed Chem.
Dictionary, 10th Ed., 1981).
Volatility: Vapor Pressure: 35 mm Hg @ 20°C (Encyc. Occupat. Health &
Safety, 1983; IARC, 1995).
Vapor Density: 5.1 (air = 1) (Patty. Indus. Hyg. & Tox, 1981-
1982).
Stability: Unstable (Goodman (1985) Pharm. Basis Therap., 7th Ed.).
Reactivity: Forms chloral hydrate when dissolved in water and forms chloral
alcoholate when dissolved in alcohol (Merck Index, 10th Ed.,
1983).
Octanol/Water
Partition Coefficient: No data.
9.1.4 Technical Products and Impurities
Chloral is produced in a technical grade with a minimum of 94% purity (Hawley (1981)
Condensed Chem. Dictionary, 10th Ed.). Instead of water, various alcohols can be added to
chloral to form hemiacetals. Chloral alcoholate and chloral betaine are simple adducts and
laboratory anesthetic alpha-chloralose is a complex adduct. Chloral is an unstable oil that does
not lend itself well to pharmaceutical formulations; therefore, in medicine it was introduced in
the form of chloral hydrate (Goodman (1985) Pharm. Basis Therap, 7th Ed.) The typical
impurities (max.) are as follows: water, 0.06%; 2,2-dichloroethane, 0.3%; 2,2,3-trichlorobutanal,
0.01%; hydrogen chloride, 0.06%; and chloroform (IARC, 1995).
9.2 PRODUCTION AND USE
The information/data presented in this section and the supporting references were
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996) and IARC
(1995).
9.2.1 Production
The principal use of chloral in the U.S. was in the manufacture of DDT. According to
IARC (1995), when the use of DDT was banned in the U.S. in 1972, the demand for chloral in
the U.S. rapidly declined. DDT is still produced in the U.S. for use in tropical countries (IARC,
1995).
- U.S. Production: (1969) 2.83 x 1010 g; (1975) 2.27 x 1010 g (SRI).
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- Import Volumes: (1984) 1.02 x 108 g (Bureau of the Census. U.S. Imports for
Consumption and General Imports, 1984).
- Export Volumes: (1972 and 1975) negligible.
9.2.2 Uses
Chloral is used in the spraying and pouring of polyurethanes (NRC, 1977); as a chemical
intermediate for the herbicide trichloroacetic acid and chloral hydrate (HSDB, 1996); used to
induce swelling of starch granules at room temperature (Kirk-Othmer, 1978-present); and as an
intermediate in DDT and other insecticides, including: methoxychlor, dichlorvos, naled, and
trichlorofon (Sittig. (1985) Handbook Toxic hazard Chem & Carcinog, 2nd Ed.; IARC, 1995).
Estimated use in the U.S. in 1975 was in the manufacture of DDT (40%); methoxychlor,
dichlorvos, and naled (10%); and miscellaneous other applications (50%) (IARC, 1995).
9.2.3 Disposal
Chloral is a potential candidate for liquid injection incineration at a temperature range of
650 to 1,600°C and a residence time of 0.1 to 2 seconds; for rotary kiln incineration at a
temperature range of 820 to 1,600°C and residence times of seconds for liquids and gases, and
hours for solids; and for fluidized bed incineration at a temperature range from 450 to 980°C and
residence times of seconds for liquids and gases, and longer for solids. (USEPA (1981)
Engineering Handbook for Hazardous Waste Incineration).
At the time of review, criteria for land treatment or burial (sanitary landfill) disposal
practices are subject to significant revision. Prior to implementing land disposal of waste residue
(including waste sludge), consult with environmental regulatory agencies for guidance on
acceptable disposal practices (HSDB Technical Review Panel; HSDB, 1996).
9.3 POTENTIAL FOR HUMAN EXPOSURE
9.3.1 Natural Occurrence
Chloral is not known to occur as a natural product (IARC, 1995).
9.3.2 Occupational
Exposure to chloral is thought to be primarily via inhalation and dermal contact with the
vapor (HSDB, 1996). Chloral has been detected in the work environment during spraying and
casting of polyurethane foam, identified as an auto-oxidation product of trichloroethylene during
extraction of vegetable oil, and also identified at the output of etching chambers in
semiconductor processing (IARC, 1995).
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9.3.3 Environmental
9.3.3.1 Environmental Releases
Chloral may be released to the environment from the synthesis of methoxychlor and
DVPP, and also from wood processing plants in the chlorination portion of the bleaching process
(HSDB, 1996). It is a reactive intermediate metabolite of trichloroethylene (IARC, 1995).
9.3.3.2 Monitored Environmental Media Levels
Air: No data.
Water: Chloral is formed during aqueous chlorination of humic substances and amino
acids (IARC, 1995). It may therefore occur in drinking water as a result of chlorine disinfection
of raw waters containing natural organic substances. The concentration of chloral measured in
drinking water in the U.S. is summarized in Table 9-1.
Chloral was reported in the drinking water supplies of several U.S. cities as follows:
Philadelphia, PA - 5 |ig/l; Seattle, WA - 3.5 |ig/l; Cincinnati, OH - 2 |ig/l; Terrebonne Parish, LA
- 1 |ig/l; New York City, NY - 0.02 |ig/l; Grand Forks, ND - 0.01 |ig/l (HSDB, 1996). In surface
water samples taken from water of New Orleans/Baton Rouge, chloral was reported at a mean
concentration of 1.0 |ig/l (HSDB, 1996).
Chloral has also been detected in the spent chlorination liquor from bleaching of sulfite
pulp after oxygen treatment at concentrations of <0.1 to 0.5 g/ton of pulp. Trace amounts have
also been reported from photocatalytic degradation of trichloroethylene in water (IARC, 1995).
Other Media: Chloral is a reactive intermediate metabolite of trichloroethylene (IARC,
1995).
Table 9-1. Concentrations of Chloral (As Chloral Hydrate)
in Drinking Water in the United States
Water Type (Location)
Tap water (reservoir)
Surface, reservoirs, lake, and groundwater
Tap water
Distribution system
Surface water
Concentration (|ig/L)
7.2-18.2
1.7-3.0
0.01-5.0
0.14-6.7
6.3-28
Source: IARC, 1995.
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9.3.3.3 Environmental Fate and Transport
9.3.3.3.1 Summary
Fate in Terrestrial Environments: The dominant fate of chloral released to soils is
rapid hydrolysis by soil water to form chloral hydrate. Volatilization is likely to be important
only in the event of a spill onto relatively dry soil.
Fate in the Atmosphere: Chloral should react rapidly with the moisture in air to form
chloral hydrate. Although photo-oxidation by hydroxyl radicals will likely occur to some extent,
the reaction rate is much slower than for hydrolysis; the half-life for the vapor phase reaction of
chloral with photochemically produced hydroxy radicals is estimated to be 10.8 hours.
Fate in Aquatic Environments: The dominant fate of any chloral released to water is
rapid hydrolysis to form chloral hydrate. Although this hydrolysis reaction is reversible, the
equilibrium constant favors the formation of chloral hydrate (27,000 to 1). Chloral is thus
essentially removed from the water. Volatilization, sorption to suspended solids, and
bioconcentration are not expected to be significant.
9.3.3.3.2 Transport and Partitioning
Soil Adsorption/Mobility: No data are available concerning the sorption of chloral to
soil. However, since chloral reacts rapidly with water to form chloral hydrate, it should also react
rapidly with soil moisture. Since chloral hydrate is extremely soluble in water (8,250 g/L) and is
not expected to sorb to soil, chloral hydrate has the potential to leach through soils (HSDB,
1996).
Volatilization: Chloral has a relatively high vapor pressure (35 torr at 25 degrees C) and
should therefore volatilize rapidly from dry surfaces. Chloral reacts rapidly with water to form
chloral hydrate thus precluding any significant volatilization of chloral from water (HSDB,
1996).
Bioconcentration: No data are available concerning the bioconcentration of chloral.
However, since chloral reacts rapidly with water to form chloral hydrate, bioconcentration would
not be expected to be a significant fate process. Since chloral hydrate is extremely soluble in
water (8,250 g/L), bioconcentration in aquatic organisms should not be significant for chloral
hydrate (HSDB, 1996).
9.3.3.3.3 Transformation and Degradation Processes
Biodegradation: No data are available concerning the biodegradability of chloral.
However, since chloral reacts rapidly with water to form chloral hydrate, biodegradation would
not be expected to be a significant fate process.
Photodegradation: The half-life for the vapor phase reaction of chloral with
photochemically produced hydroxy radicals is estimated to be 10.8 hours. No data are available
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on the photolytic sensitivity of chloral. However, acetaldehyde has a UV absorption maximum at
293 nm which suggests that chloral will also absorb some UV light (HSDB, 1996).
Hydrolysis: Chloral reacts exothermically with water to form chloral hydrate. Because
the equilibrium constant for this reaction is 3.6 x 10"5, very little chloral will remain in solution
(HSDB, 1996)
9.4 HUMAN EXPOSURE AND POPULATION ESTIMATES
9.4.1 General U.S. Population
The general population can be exposed to chloral during its production and use, from
drinking chlorinated water, and from pharmaceutical use (IARC, 1995).
9.4.2 Occupational Exposure
Results of the National Occupational Exposure Survey conducted between 1981 and 1983
indicate that 2,757 employees in the U.S. were potentially exposed to chloral (IARC, 1995). The
estimate was based on a survey of companies and did not involve measurements of actual
exposure.
9.4.3 Consumer Exposure
No data concerning consumer exposure were found.
9.5 CHAPTER SUMMARY
Table 9-2 summarizes the findings of chloral.
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Table 9-2. Chloral Summary
Uses
Production
Releases
Properties/Fate
Media Levels
General Population
Exposure
Special Population
Exposures
Estimates
Chemical intermediate for manufacture of
pesticides; used in spraying and pouring of
polyurethanes
2.3xl07kg
No available data
Soluble in water; rapid hydrolysis to chloral
hydrate; no significant bio-concentration
expected
Air: no data
Drinking water supplies: six U.S. cities -
0.02 ug/1 to 5 mg/1
No available data
2,757 employees potentially exposed
Support
Well documented
1975 data
Data from early 1980s
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10.0 CHLORAL HYDRATE
10.1 CHEMICAL AND PHYSICAL PROPERTIES
The information/data presented in this section and the supporting references were
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).
10.1.1 Nomenclature
CAS No.
Synonyms:
302-17-0
1,1,1 -trichloro-2,2-dihydroxyethane; 2,2,2-trichloro-1,1 -ethanediol;
trichloroacetaldehyde hydrate; trichloroacetaldehyde monohydrate;
trichloroethylidene glycol; 2,2,2-trichloroethane-l,l-diol
Trade Names: Kessodrate, Noctec, Phaldrone, Sontec, Chloralvan, Chloralex
10.1.2 Formula and Molecular Weight
Molecular Formula:
Molecular Weight:
C2H3C1302
165.42
10.1.3 Chemical and Physical Properties
Description:
Boiling Point:
Melting Point:
Density:
Spectroscopy Data:
Solubility:
Transparent, colorless crystals (Sax, 1984); aromatic,
penetrating and slightly acrid odor; slightly bitter, caustic taste
(Merck Index, llth Ed., 1989).
96.3°C @ 764 mm Hg (decomp) (CRC Handbook Chem. &
Physics, 1991-1992).
-57°C (Merck Index, llth Ed., 1989).
1.908 @ 20°C/4°C (CRC Handbook Chem. & Physics, 1991-
1992).
IR: 5423 (Coblentz Society Spectral Collection); NMR: 10362
(Sadtler Research Laboratories Spectral Collection); Mass:
1054 (Atlas of Mass Spectral Data) (Weast, 1985); intense
mass spectral peaks: 82 m/z, 111 m/z, 146 m/z (Pfleger, 1985).
2.4 g/ml water @ 0°C; 14.3 g/ml water @ 40°C; 8.3 g/ml water
at 25°C. Sparingly soluble in turpentine, petroleum ether,
benzene, toluene, carbon tetrachloride; 1 g/68 g carbon
disulfide; 1 g/1.3 ml alcohol; 1 g/1.4 ml olive oil; freely soluble
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in acetone, methyl ethyl ketone; 1 g/2 ml chloroform; 1 g/1.5
ml ether; 1 g/0.5 ml glycerol (Merck Index, 11th Ed., 1989).
Volatility: No data.
Stability: Slowly volatilizes on exposure to air (Merck Index, 11th Ed.,
1989). Aqueous solutions of chloral hydrate decomposed
rapidly when exposed to ultraviolet light, with the formation of
hydrochloric acid, trichloroacetic acid, and formic acid. A 1%
solution lost about 5% of its strength after storage at room
temperature for 20 weeks; aqueous solutions are likely to
develop mold growth (Martindale. Extra Pharmacopeia, 28th
Ed., 1982).
Reactivity: No data.
Octanol/Water
Partition Coefficient: log Kow = 0.99 (Hansch. Log P Database, 1987)
10.1.4 Technical Products and Impurities
Dosage forms for chloral hydrate are the following: capsules: 250 and 500 mg, and 1 g;
elixir: 500 mg/5 ml; suppositories: 325, 500, and 650 mg; syrup: 250 and 500 mg/5 ml
(Remington's Pharm. Sci., 17Ed., 1985). Noctec capsules contain 250 or 500 mg chloral hydrate
per capsule; Noctec syrup contains 500 mg chloral hydrate per 5 cc (AHFS drug Information 92
Plus Suppl's). Chloral hydrate is produced in technical and USP grades (Sax, 1987). For
chloropent injection; intravenous anesthetic; each ml contains chloral hydrate 42.5 mg;
magnesium sulfate 21.2 mg; pentobarbital 8.86 mg; ethyl alcohol 14.25%; propylene glycol
33.8%; and purified water, qs (for cattle and horses) (Vet Pharm. & Biolog., 1982-1983).
Chloral hydrate capsules contain not less than 95.0% and not more than 110.0% of the labeled
amount of chloral hydrate; chloral hydrate syrup contains not less than 95.0% and not more than
110.09% of the labeled amount of chloral hydrate (USPC. USP XXH & NF XVH 1990, Plus
Suppl's).
10.2 PRODUCTION AND USE
The information/data presented in this section and the supporting references were
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).
10.2.1 Production
U.S. Production: (1972) 1.14 x 1010 g (anhydrous chloral); (1975) 5.9 x 108 g
(SRI).
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Import Volume: (1972) 2.83 x 107 g; (1975) 4.8 x 107 g (SRI); (1984) 5.41 x 106
g; 4.67 x 1012 g (Bureau of the Census. U.S. Imports for
Consumption and General Imports, 1984; 1986).
Export Volume: No data.
10.2.2 Uses
Chloral hydrate is used in medication as a hypnotic and sedative (Merck Index, 11th
Ed., 1989; IARC, 1995). It is also used as a rubefacient in topical preparations (AHFS Drug
Information 92 Plus Suppl's); veterinary medication (VetPharm. & Biolog., 1982-1983); and as
a glue peptizing agent (Kirk-Othmer, 1980).
10.2.3 Disposal
Chloral hydrate is a waste chemical stream constituent which may be subjected to
ultimate disposal by controlled incineration, preferably after mixing with another combustible
fuel. Care must be exercised to assure complete combustion to prevent the formation of
phosgene; an acid scrubber is necessary to remove the halo acids produced (USEPA. 1981.
Engineering Handbook of Hazardous Waste Leachate). Solvent extraction is a wastewater
treatment technology that has been investigated for chloral hydrate (USEPA. 1982. Engineering
Handbook of Hazardous Waste Leachate).
10.3 POTENTIAL FOR HUMAN EXPOSURE
10.3.1 Natural Occurrence
Chloral hydrate is not known to occur as a natural product (IARC, 1995).
10.3.2 Occupational
Specific information concerning potential for occupational exposure were not found.
10.3.3 Environmental
10.3.3.1 Environmental Releases
Specific data on environmental releases of chloral hydrate were not found.
10.3.3.2 Monitored Environmental Media Levels
Air: No data.
Water: Chloral hydrate may occur in drinking water as a result of chlorine disinfection
of raw waters containing natural organic substances. The concentration of chloral measured in
drinking water (as chloral hydrate) in the U.S. is summarized in Section 9, Table 9-1.
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Other Media: Chloral hydrate has been detected in human milk (HSDB, 1996). Data
were not available in HSDB (1996) on the mechanism whereby the breast milk became
contaminated.
10.3.3.3 Environmental Fate and Transport
10.3.3.3.1 Summary
The summary is based on the data presented in the subsequent fate and transport
subsections.
Fate in Terrestrial Environments: Since chloral hydrate is very soluble in water
(8,250 g/L), it is not expected to sorb to soil and thus has the potential to leach through soils. No
information is available on the biodegradation of chloral hydrate.
Fate in the Atmosphere: Any chloral hydrate released to the atmosphere is expected to
be readily scavenged during precipitation events. Chloral hydrate may also undergo photolysis,
but the available data are not adequate to determine its relative importance.
Fate in Aquatic Environments: Because of its very high water solubility, chloral
hydrate is not expected to volatilize, sorb to suspended solids or sediments, or bioconcentrate.
No information is available on the biodegradation of chloral hydrate.
10.3.3.3.2 Transport and Partitioning
Soil Adsorption/Mobility: No data are available concerning the sorption of chloral
hydrate to soil. However, since chloral hydrate is very soluble in water (8,250 g/L), it is not
expected to sorb to soil and thus has the potential to leach through soils (HSDB, 1996).
Volatilization: Although vapor pressure data for chloral hydrate are not readily
available, chloral hydrate has been reported to slowly volatilize from surfaces when exposed to
air. Because of its very high water solubility, volatilization from water is not expected to be
significant (HSDB, 1996).
Bioconcentration: No data are available concerning the bioconcentration of chloral
hydrate. However, since chloral hydrate is very soluble in water (8,250 g/L), bioconcentration in
aquatic organisms should not be significant (HSDB, 1996).
10.3.3.3.3 Transformation and Degradation Processes
Biodegradation: No information is available on the biodegradation of chloral hydrate
(HSDB, 1996).
Photodegradation: Although no studies have apparently been published that
quantitatively have examined direct atmospheric photolysis of chloral hydrate, a 1 percent
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aqueous solution of chloral hydrate was reported to have lost 5 percent of its strength after
storage for 20 weeks at room temperature. Hydrochloric acid, trichloroacetic acid, and formic
acid were formed as products (HSDB, 1996).
Hydrolysis: Hydrolysis is not expected to be a significant fate process for chloral
hydrate.
10.4 HUMAN EXPOSURE AND POPULATION ESTIMATES
Human exposure to chloral hydrate can occur during its production and use, from
pharmaceutical use, and from drinking chlorinated water (IARC, 1995). Specific exposure data
and data on estimates of exposed populations were not found. The general population may be
potentially exposed from ingestion of drinking water contaminated with chloral hydrate. The
occupational population may be exposed in the workplace during production and use. The
consumer population may be potentially exposed from use of pharmaceuticals.
10.5 CHAPTER SUMMARY
Table 10-1 summarizes the findings of chloral hydrate.
Table 10-1. Chloral Hydrate Summary
Uses
Production
Releases
Properties/Fate
Media Levels
General Population
Exposure
Special Population
Exposures
Estimates
Pharmaceutical
5.9xl05kg
No available data
Water soluble; no significant
bioconcentration expected; no information
on biodegradation
No available data
No available data
No available data
Support
Well documented
1975 data
102
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11.0
MONOCHLOROACETIC ACID
11.1
CHEMICAL AND PHYSICAL PROPERTIES
The information/data presented in this section and the supporting references were
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).
11.1.1 Nomenclature
CAS No.:
Synonyms:
79-11-8
Acetic acid; chloro-; alpha-chloroacetic acid; chloracetic acid;
chloroethanoic acid; monochloroacetic acid; monochloroethanoic acid
Trade Names: NCI-C60231
11.1.2 Formula and Molecular Weight
Molecular Formula:
Molecular Weight:
C2H3C102
94.50
11.1.3 Chemical and Physical Properties
Description:
Boiling Point:
Melting Point:
Density:
Spectroscopy Data:
Solubility:
Colorless or white crystals (Merck Index, 11th Ed., 1989).
Characteristic penetrating odor similar to vinegar.
All three forms (alpha, beta, gamma) boil at 189° C (Merck
Index, llth Ed., 1989).
Exists in three physical modifications: alpha 63° C; beta 55-
56° C; gamma 50° C (Merck Index, 11th Ed., 1989).
1.4043 @ 40° C/4° C (Gardner's Chem Synonyms, Trade
Names, 1987).
Index of Refraction: 1.4351 @ 55° C/D; SadtlerRef. Number:
2094 (IR, Prism (Weast, 1988-89); IR: 5567 (Coblentz Society
Spectral Collection) (Weast, 1985); NMR: 128 (Sadtler
Research Laboratories Spectral Collection) (Weast, 1985);
Mass; 196 (Weast, 1985).
Very soluble in water, slightly soluble in chloroform (Weast,
1988-89); Soluble in acetone, carbon disulfide (Weast, 1979);
soluble in benzene (Merck Index, 1989); soluble in ethanol,
diethyl ether (Worthing, Pesticide Manual, 1979); soluble in
carbon tetrachloride (Encyc. Occupat. Health & Safety, 1983).
103
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Volatility: Vapor Pressure: 1 mm Hg @ 43.0° C (Patty, Indus. Hyg. &
Tox., 3rd Ed., 1981-82).
Vapor Density: 3.26 (air = 1) (Sax, 1984).
Stability: No data.
Reactivity: Highly reactive; chemically reacts with ammonia to form
glycine and with aniline to form a precursor for indigo dyes
(Encyc. Occupat. Health & Safety, 1983).
Octanol/Water
Partition Coefficient: log Kow = 0.22 (Hansch, 1981)
11.1.4 Technical Products and Impurities
Monochloroacetic acid is produced in technical and medicinal grades with 99.5%
purity. Data were not available for impurities.
11.2 PRODUCTION AND USE
The information/data presented in this section and the supporting references were
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).
11.2.1 Production
U.S. Production: (1978) 3.50 x 1010 g (SRI); (1982) probably greater than 6.81 x 106 g
(SRI); Chemical Int. For sodium carboxymethyl cellulose, 60%; for
herbicides, 30%; for other derivatives (e.g., glycine, thioglycolic acid,
Pharmaceuticals, and indigoid dyes), 10% (SRI, 1979).
Import Volumes: (1978) 1.25x 1010g(SRI); (1982) 1.35x 1010g(SRI).
11.2.2 Uses
Monochloroacetic acid is used as a chemical intermediate for pharmaceuticals (e.g.,
vitamin A); chemical intermediate for indigoid dyes; and as a herbicide (Merck Index, 1989). It
is also used as a preservative, bacteriostat, intermediate in production of synthetic caffeine;
carboxymethyl cellulose; ethyl chloracetate; glycine; scariosine; thioglycolic acid; EDTA; 2,4-D;
2,4,5-T (Hawley's Condensed Chem. Diet., 11th Ed., 1987). It has also been recommended as a
defoliant (Pesticide Manual, 4th Ed., 1974, p. 106).
11.2.3 Disposal
No data were identified.
104
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11.3 POTENTIAL FOR HUMAN EXPOSURE
11.3.1 Natural Occurrence
No information on the natural occurrence of chloracetic acid was found.
11.3.2 Occupational
No specific information on potential for occupational exposure of chloracetic acid was
found.
11.3.3 Environmental
11.3.3.1 Environmental Releases
Chloracetic acid may enter the environment in emissions and wastewater from its
production and use as a chemical intermediate primarily in the manufacture of chlorophenoxy
herbicides and carboxymethyl cellulose. Such releases of the chemical would be limited to
industrial settings (HSDB, 1996). Chloroacetic acid has been used as a pre-emergent herbicide
and defoliant, and if it is still used for these applications, its use would constitute an emission
source and ground contamination of a more general nature (HSDB, 1996).
Total Toxic Release (TRI) releases for years 1987 to 1994 are shown in Table 11-1.
The receiving media are air, water, land, and for underground injection, POTW transfer, and
other transfer. These releases are reported from manufacturing and processing facilities. Only
certain facilities are required to report, and therefore may not capture all releases.
Table 11-1. Release of Chloroacetic Acid (Ibs/yr)
Year
1987
1988
1989
1990
1991
1992
1993
1994
Number of
Reporting
Facilities
34
37
35
37
36
31
29
32
Fugitive Air
Releases
24229
21660
20616
20660
60745
10778
5796
5983
Stack Air
Releases
4383
5159
4229
4759
446920
1024
767
710
Surface
Water
Release
29956
850
1524
1691
1696
3199
8719
10178
Underground
Injection
280
10
10
0
0
0
0
0
Land
Disposal
0
0
0
0
123675
0
750
950
POTW
Transfer
1380
10727
9717
1785
3279
1792
1433
1015
Other
Transfers
4010
9406
4096
6779
6444
3147
2219
6259
Total
64272
47849
40227
35711
642795
19971
19713
25127
Source: TRI, 1996.
105
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11.3.3.2 Monitored Environmental Media Levels
Air: Data were not found for monitored levels in air.
Water: Between the spring of 1988 and the winter of 1989, grab samples were
collected at the clearwell effluents (after disinfection) from 35 treatment facilities and analyzed
by gas chromatography/mass spectroscopy (GC/MS). The concentration of monochloroacetic
acid was <1.0 to 1.2 |ig/L (U.S. EPA, 1994). Chloroacetic acid was also found in a study where
concentrated humic acid from a coastal North Carolina lake was chlorinated (U.S. EPA, 1994).
Other Media: Data were not found for monitored levels in other media.
11.3.3.3 Environmental Fate and Transport
11.3.3.3.1 Summary
The summary is based on the data presented in the subsequent fate and transport
subsections.
Fate in Terrestrial Environments: The dominant fate of chloroacetic acid released to
or into soils is biodegradation. Although no soil biodegradation studies with chloroacetic acid
have been reported, studies with wastewater and river water inocula indicate that biodegradation
in soil will be a relatively rapid process. This ready biodegradability should minimize the
possibility of any significant leaching of chloroacetic acid into groundwater.
Fate in the Atmosphere: Because of its high water solubility and slow rates of photo-
oxidation and photolysis, any chloroacetic acid released into the atmosphere will likely be
scavenged during precipitation events before any significant photodegradation occurs.
Fate in Aquatic Environments: The dominant fate of chloroacetic acid released to
surface waters is biodegradation (predicted half-life of days). Bioconcentration and sorption to
sediments and suspended solids are not expected to be significant transport/partitioning
processes.
11.3.3.3.2 Transport and Partitioning
Soil Adsorption/Mobility: The relatively low predicted soil adsorption coefficient (log
Koc) for chloroacetic acid (0.08) indicates that adsorption to soil, sediment, and suspended solids
is not a significant fate process. As a consequence, chloroacetic acid has the potential for high
mobility in soil; however, the extent of migration will be minimized because of the ready
biodegradability of chloroacetic acid (HSDB, 1996; U.S. EPA, 1996).
Volatilization: The very low predicted Henry's Law constant for chloroacetic acid
(<10"7 atm-m3/mol) indicates that minimal volatilization is expected from water bodies. Because
of its relatively low vapor pressure (<1 torr), minimal volatilization from soil surfaces is
expected (HSDB, 1996; U.S. EPA, 1996).
106
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Bioconcentration: A bioconcentration factor of 0.86 is predicted for chloroacetic acid
based on its very low measured log octanol/water partition coefficient of 0.22. Therefore,
bioconcentration in aquatic organisms should not be significant and there is little potential for
biomagnification in the food chain (HSDB, 1996; U.S. EPA, 1996).
11.3.3.3.3 Transformation and Degradation Processes
Biodegradation: Chloroacetic acid is expected to undergo ultimate biodegradation in
aerobic environmental settings with a half-life on the order of days. Degradation under anaerobic
conditions is expected to proceed more slowly with a predicted half-life on the order of weeks.
In laboratory tests using sewage or acclimated sludge inocula, chloroacetic acid readily
undergoes biodegradation with greater than 70-90 percent degradation being reported in 5-10
days. The results of river water studies indicate 73 percent mineralization (i.e., conversion to
carbon dioxide) in 8-10 days (HSDB, 1996; U.S. EPA, 1996; Howard et al., 1991).
Photodegradation: Photolysis in the atmosphere or in aquatic environments is
expected to proceed very slowly with predicted half-lives on the order of months to years.
Chloroacetic acid does not appreciably absorb UV light above 290 nm and thus will not directly
photolyze. The presence of sensitizers such as p-cresol and tryptophan that generate superoxide
radicals has been shown to increase the rate of photodechlorination by up to 16-fold. Based on
the estimated reaction rate constant of chloroacetic acid with hydroxyl radicals, the estimated
half-life of chloroacetic acid in the atmosphere is on the order of weeks to months (HSDB, 1996;
Howard et al., 1991).
Hydrolysis: Based upon the results of darkened controls during photolysis experiments,
the half-life of chloroacetic acid is on the order of years (HSDB, 1996; Howard et al., 1991)
11.4 HUMAN EXPOSURE AND POPULATION ESTIMATES
Data were not found for human exposure and population estimates.
11.5 CHAPTER SUMMARY
Table 11-1 summarizes the findings of monochloroacetic acid.
107
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Table 11-2. Monochloroacetic Acid Summary
Uses
Production
Releases
Properties/Fate
Media Levels
General Population
Exposure
Special Population
Exposures
Estimates
Chemical intermediate; herbicide
6.81xl03kg/yr
25, 127 Ibs- all media
Very soluble in water; no significant
bioconcentration or biodegradation expected
Air: no available data
Water samples from treatment facilities -
<1.0tol.2ug/l
No available data
No available data
Support
Well documented
1982 data
1 994 TRI data
35 facilities
108
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12.0
DICHLOROACETIC ACID
12.1 CHEMICAL AND PHYSICAL PROPERTIES
The information/data presented in this section and the supporting references were
obtained from IARC Monographs, Volume 63, 1995.
12.1.1 Nomenclature
CAS No.:
Synonyms:
79-43-6
Bichloracetic acid; DC A; CDA (acid); DCAA; dichloracetic acid;
dichlorethanoic acid; dichloroethanoic acid; 2,2-dichloroethanoic acid
12.1.2 Formula and Molecular Weight
Molecular Formula:
Molecular Weight:
C2H2C1202
128.94
12.1.3 Chemical and Physical Properties
Description:
Boiling Point:
Melting Point:
Density:
Spectroscopy Data:
Solubility:
Volatility:
Colorless to slightly yellowish liquid with a pungent acid-like
odor (Merck Index, 1989; Hoechst Chemicals, 1990).
194°C
13.5°C
1.5634@20°C/4°C
Infrared (prism [2806]; grating [36771]), nuclear magnetic
resonance (proton [116], C-13 [500], and mass spectral data
have been reported (Sadtler Research Laboratories, 1980;
IARC, 1995).
Soluble in water, acetone, ethanol, and diethyl ether; also
soluble in ketones, hydrocarbons, and chlorinated hydrocarbons
(IARC, 1995). In aqueous solution, dichloroacetic acid and
dichloroacetate exist as an equilibrium mixture, the proportions
of each depending primarily on the pH of the solution. The pKa
of dichloroacetic acid is 1.48 @ 25°C.
Vapor Pressure - 0.19 mbar (19 Pa) @ 20°C (Hoechst
Chemicals, 1990).
Vapor Density - No data.
109
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Reactivity: Highly corrosive and attacks metals; releases hydrogen chloride
gas (see IARC, 1992) when heated (Hoechst Chemicals, 1990).
Octanol/Water
Partition Coefficient: log P, 0.92 (Hansch, 1995)
12.1.4 Technical Products and Impurities
Dichloroacetic acid is available commercially at a purity of 99% with a maximum of
0.3% water (Hoechst Chemicals, 1990; Spectrum Chemical Mfg Corp., 1994)
12.2 PRODUCTION AND USE
12.2.1 Production
Figures for the production and use of dichloroacetic acid in the U.S. or throughout the
world are not available (IARC, 1995).
12.2.2 Uses
Dichloroacetic acid is presently of little economic importance. Its acid chloride and
methyl ester, however, are used as intermediates in the manufacture of agrochemicals and the
pharmaceutical, chloramphenicol (IARC, 1995). Dichloroacetic acid is also a starting material
for the production of glyoxylic acid, dialkyloxy and diaryloxy acids, and sulfonamides. The
compound is used as a test reagent for analytical measurements during the manufacture of
polyethylene terephthalate and as a medical disinfectant, in particular as a substitute for
formaldehyde (IARC, 1995). It has been considered for use in the treatment of lactic acidosis,
diabetes mellitus, hyperlipoproteinaemia, and several other disorders; however, it has never been
marketed for any of these purposes (Merck Index, 1989).
12.2.3 Disposal
No information concerning disposal methods for dichloroacetic acid was identified.
12.3 POTENTIAL FOR HUMAN EXPOSURE
12.3.1 Natural Occurrence
Dichloroacetic acid is not known to occur as a natural product.
12.3.2 Occupational
No specific information concerning the potential for human exposure in an occupational
setting was found.
110
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12.3.3 Environmental
12.3.3.1 Environmental Releases
No information concerning environmental releases of dichloroacetic acid was found.
12.3.3.2 Monitored Environmental Media Levels
Air: No data available.
Water: Dichloroacetic acid is produced as a by-product during aqueous chlorination of
humic substances and therefore it may occur in drinking water after chlorine disinfection of raw
waters containing natural substances (IARC, 1995). The concentrations of dichloroacetic acid
measured in various water sources and reported in various studies are summarized in Table 12-1.
According to IARC (1995), it has been identified as a major chlorinated by-product of the
photocatalytic degradation of tetrachloroethylene in water and a minor by-product of the
degradation of trichoroethylene.
Other Media: In humans, dichloroacetic acid is a reactive intermediate metabolite of
trichloroethylene and an end-metabolite of 1,1,1,2-tetrachloroethane. Dichloroacetic acid has
also been reported as a biotransformation product of methoxyflurane (IARC, 1995) and
dichlorvos (IARC, 1995). It may occur in the tissues and fluids of animals treated with
dichlorvos for helminthic infections (IARC, 1995).
Table 12-1. Concentrations of Dichloroacetic Acid in Water
Water Type (Location)
Drinking Water (chlorinated tap water (USA)
Drinking Water (chlorinated surface, reservoir, lake, and ground-water) (USA)
Chlorinated Surface Water (USA)
Chlorinated Drinking Water (USA)
Swimming Pool (Germany)
Surface Water (downstream from a paper mill) &Austria)
Biologically Treated Kraft Pulp Mill Effluent (Malaysia)
Concentration Range (ng/L)
63.1 -133
5.0-7.3
9.4-23
8-79
indoors: 0.2 - 10.6
open air: 83.5- 181. Oa
<3 - 522
14-18
a The higher levels found in open-air swimming pools may be due to the input of organic material by swimmers.
Source: IARC, 1995.
Ill
-------
12.3.3.3 Environmental Fate and Transport
No information is readily available on the environmental fate and transport of
dichloroacetic acid. However, its environmental fate is expected to be similar to that of
monochloroacetic acid and trichloroacetic acid. The environmental fate and transport of
monochloroacetic acid and trichloroacetic acid are discussed in Sections 11.3.3.3 and 13.3.3.3,
respectively.
12.4 HUMAN EXPOSURE AND POPULATION ESTIMATES
12.4.1 General U.S. Population
The general population is potentially exposed to dichloroacetic acid through the
ingestion of chlorinated drinking water, contact with surface water contaminated with this
chemical, and chlorinated water in swimming pools.
12.4.2 Occupational Exposure
The National Occupational Exposure Survey conducted between 1981 and 1983
indicated that 1,592 employees in the United States were potentially exposed to dichloroacetic
acid in 39 facilities (IARC, 1995).
12.4.3 Consumer Exposure
Data were not found on consumer exposure to dichloroacetic acid.
12.5 CHAPTER SUMMARY
Table 12-2 summarizes the findings of dichloroacetic acid.
Table 12-2. Dichloroacetic Acid Summary
Uses
Production
Releases
Properties/Fate
Media Levels
General Population
Exposure
Special Population
Exposures
Estimates
Chemical intermediate
No available data
No available data
Water soluble
Water: 5-133 ug/1
No available data
1,592 employees potentially exposed
Support
Data from early 1980s
112
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13.0
TRICHLOROACETIC ACID
13.1 CHEMICAL AND PHYSICAL PROPERTIES
The information/data presented in this section and the supporting references were
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).
13.1.1 Nomenclature
CAS No.:
Synonyms:
Trade Names:
70-03-9
Acetic acid; trichloro-,
-------
slightly soluble in carbon tetrachloride (CRC Handbook Chem.
& Physics, 76th Ed., 1995-96).
Volatility: Vapor Pressure - 1 mm Hg @ 51.0°C (solid) (CRC Handbook
Chem. & Physics, 72nd Ed., 1991-1992).
Stability: Stable in the absence of moisture (Pesticide Manual, 8th Ed.,
1987); 2-year shelf life minimum, may cake however
(Herbicide Hdbk, 5th Ed., 1983).
Reactivity: Reacts with moisture, iron, zinc, aluminum, strong oxidizers
(Note: decomposes on heating to form phosgene and hydrogen
chloride. Corrosive to metals.) (NIOSH Pocket Guide Chem.
Haz., 1994).
Octanol/Water
Partition Coefficient: No data.
13.1.4 Technical Products and Impurities
Trichloroacetic acid is produced in a technical grade (chemically pure: a grade
designation signifying a minimum of impurities, but not 100% purity) and a USP grade
(Hawley's Condensed Chem. Diet., 12th Ed., 1993).
13.2 PRODUCTION AND USE
The information/data presented in this section and the supporting references were
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996).
13.2.1 Production
- U.S. Production: (1975) greater than 3.60 x 106 g; (1976) greater than 2.27 x
106g(SRI).
- Import Volumes: (1984) 3.67 x 109 g/chloroacetic acid (Bureau of the
Census. U.S. Imports for Consumption and General
imports, 1984).
- Export Volumes: (1984) 8.60 x 109 g (Halogenated Hydrocarbons, Bureau of
the Census. U.S. Exports, 1984).
13.2.2 Uses
Trichloroacetic acid is used as a chemical intermediate for the production of ethylene
glycol bis(trichloroacetate) and herbicides, sodium trichloroacetate and monuron-TCA; and used
as a lab reagent for biological applications (SRI). TCA has been used as an astringent and
antiseptic, and polymerization catalyst (Kirk-Othmer. Encyc. Chem. Tech., 4th Ed., Vol. 1,
114
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1991-present). About 21,000-23,000 t/a of the TCA sodium salt are used worldwide as a
selective herbicide (Ullmann's Encyc. Indus! Chem., 5th Ed., 1985-present).
13.2.3 Disposal
Reverse osmosis is a wastewater treatment technology that has been investigated for
trichloroacetic acid (USEPA, 1982, Management of Hazardous Waste Leachate). After mixing,
transfer into a drum and fill with water for drainage after 24 hours (Tox. & Hazard. Indus. Chem.
Safety Manual, 1988).
At the time of review, criteria for land treatment or burial (sanitary landfill) disposal
practices are subject to significant revision. Prior to implementing land disposal of waste residue
(including waste sludge), consult with environmental regulatory agencies for guidance on
acceptable disposal practices (HSDB Scientific Review Panel; HSDB, 1996).
13.3 POTENTIAL FOR HUMAN EXPOSURE
13.3.1 Natural Occurrence
Trichloroacetic acid is not known to occur naturally (IARC, 1995).
13.3.2 Occupational
The probable routes of occupational exposure are dermal contact and inhalation.
Trichloroacetic acid is the major end metabolite of trichloroethylene and tetrachloroethylene in
humans and has been used as a biological marker of exposure to these compounds (IARC, 1995).
Additionally, it is a metabolite of 1,1,1-trichoroethane and 1,1,1,2-tetrachloroethane and chloral
hydrate is rapidly oxidized to trichloroacetic acid in humans (IARC, 1995).
13.3.3 Environmental
13.3.3.1 Environmental Releases
The production of trichloroacetic acid and its use in organic synthesis, medicine,
Pharmaceuticals, and as a herbicide may result in its release to the environment through
wastestreams (HSDB, 1996).
13.3.3.2 Monitored Environmental Media Levels
Air: No data.
Water: The concentrations of trichloroacetic acid in water are presented in Table 13-1.
Other Media: Trichloroacetic acid has been detected in the following foods(IARC,
1995):
115
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Table 13-1. Concentrations of Trichloroacetic Acid in Water
Water Type (Location)
Chlorinated Tap Water (USA) (drinking water)
Chlorinated Drinking Water (USA)
Raw Water (USA)
Chlorinated Surface, Reservoir, Lake, and Groundwaters
(USA)
Chlorinated Surface Water (USA)
Chlorinated Drinking Water (USA)
Raw Water (USA)
Concentration Range (ng/L)
33.6-161
4.23-53.8
95-2,120
4.0-6.0
7.4 - 22
15-64
60-1,630
Source: IARC, 1995.
Seed of wheat, barley, and oats after treatment with trichloroacetic acid as
postemergent herbicide;
Fruits and vegetables after irrigation with trichloroacetic acid contaminated water
(trace levels); and
Field bean pods and seeds (0.13 to 0.43 mg/kg)
Concentration of trichloracetic acid was in irrigation water after the application of the
sodium salt (herbicide) to control canary grass on the banks of dry canals in the State of
Washington. The levels measured ranged from 53 to 297 ppb (HSDB, 1996).
13.3.3.3 Environmental Fate and Transport
13.3.3.3.1 Summary
The summary is based on the data presented in the subsequent fate and transport
subsections.
Fate in Terrestrial Environments: The dominant fate of trichloroacetic acid released
onto or into soils is biodegradation. Studies with wastewater and soil indicate that aerobic
biodegradation in soil will occur within weeks to months depending on the soil type, moisture
and temperature. However, the low reported Koc for trichloroacetic acid indicates that
trichloroacetic acid should have high mobility in soil and, therefore, significant leaching to
groundwater could occur, particularly in sandy soils.
Fate in the Atmosphere: Because of its moderate vapor pressure (<1 mm Hg at 25
degrees C), trichloroacetic acid should exist predominantly in the vapor phase in the atmosphere.
Vapor phase trichloroacetic acid is degraded in the atmosphere by reaction with photochemically
produced hydroxyl radicals; the half-life for this reaction is estimated to be about 31 days.
116
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Fate in Aquatic Environments: The dominant fate of trichloroacetic acid released into
surface waters is biodegradation (predicted weeks to months). Bioconcentration, sorption to
sediments and suspended solids, and volatilization are not expected to be significant
transport/partitioning processes.
13.3.3.3.2 Transport and Partitioning
Soil Adsorption/Mobility: The relatively low predicted soil adsorption coefficient (Koc
= 1) for trichloroacetic acid indicates that adsorption to soil, sediment, and suspended solids is
not a significant fate process. Several laboratory and field soil studies confirm that
trichloroacetic acid shows little sorption to soils. As a consequence, trichloroacetic acid has the
potential for high mobility in soil (HSDB, 1996).
Volatilization: The very low predicted Henry's Law constant for trichloroacetic acid
(<10"7 atm-m3/mol) indicates that minimal volatilization is expected from water bodies. Because
of its relatively low vapor pressure (<1 mm Hg), minimal volatilization from soil surfaces is
expected (HSDB, 1996).
Bioconcentration: Bioconcentration factors measured in carp range from 0.4 to 1.7.
Therefore, bioconcentration in aquatic organisms should not be significant and there is little
potential for biomagnification in the food chain (HSDB, 1996).
13.3.3.3.3 Transformation and Degradation Processes
Biodegradation: Trichloroacetic acid has been demonstrated to be undergo
biodegradation under aerobic conditions in soil and in laboratory tests with activated sludge
inocula (half-lives on the order of weeks to months). However, a noticeable lag period was
observed (i.e., a period in which slow degradation was followed by rapid degradation).
Degradation appears to be favored by warm moist conditions conducive to high microbiological
activity (HSDB, 1996).
Photodegradation: Based on the estimated reaction rate constant of trichloroacetic acid
with hydroxyl radicals, the estimated half-life of trichloroacetic acid in the atmosphere is about
31 days. No information is available on the photolysis of trichloroacetic acid. However,
monochloroacetic acid does not appreciably absorb UV light above 290 nm and thus will not
directly photolyze; the presence of sensitizers such as p-cresol and tryptophan that generate
superoxide radicals has been shown to increase the rate of photodechlorination by up to 16-fold
(HSDB, 1996; Howard et al., 1991).
Hydrolysis: No information is available on the hydrolytic half-life of trichloroacetic
acid. However, the hydrolytic half-life of monochloroacetic acid is on the order of years based
on the results of darkened controls during photolysis experiments (HSDB, 1996; Howard et al.,
1991)
117
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13.4 HUMAN EXPOSURE AND POPULATION ESTIMATES
13.4.1 General U.S. Population
Based on available data, the general population could be potentially exposed to
trichloroacetic acid through ingestion of drinking water and foods contaminated with this
chemical.
13.4.2 Occupational Exposure
Estimates from aNIOSH survey conducted between 1981 and 1983 show that 35,124
employees in the U.S. were potentially exposed occupationally to trichloroacetic acid (IARC,
1995). This potentially exposed population were employees in seven different industries and
1,562 plants (IARC, 1995).
Trichloroacetic acid (3-116 mg/g creatinine) was found in the urine of employees in the
metal degreasing industry. These employees were exposed to trichloroethylene (HSDB, 1996).
13.4.3 Consumer Exposure
Data were not found for consumer exposures.
13.5 CHAPTER SUMMARY
Table 13-2 summarizes the findings of trichloroacetic acid.
Table 13-2. Trichloroacetic Acid Summary
Uses
Production
Releases
Properties/Fate
Media Levels
General Population
Exposure
Special Population
Estimates
Chemical intermediate; herbicide
More than 2,270 kg
No available data
Water soluble; no significant
bioconcentration is expected
Air: no data
Drinking water: 4.2 to 161 ug/1
Raw water: 60 to 1,630 ug/1
35,124 employees potentially
Support
Well documented data
1976 data
Data from early 1980s
118
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14.0 DICHLORO-VINYL CYSTEINE
No information is readily available for this chemical.
119
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