> EPA
United States
Environmental Protection
Agency
Office of Water October 1981
Regulations and Standards (WH-553) EPA-440/4-85-019
Washington DC 20460
Water
An Exposure
and Risk Assessment
for Trichloroethylene
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DISCLAIMER
This is a contractor's final report, which has been reviewed by the Monitoring and Data Support
Division, U.S. EPA. The contents do not necessarily reflect the views and policies of the U.S.
Environmental Protection Agency, nor does mention of trade names or commercial products
constitute endorsement or recommendation for use.
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1 -TEPORT DOCUMENTATION
PAGE
1. REPORT NO.
EPA-440/4-85-019
3. Recipient1* Accenlon No.
„,. TIB» Mtf Subtitle
An Exposure and Risk Assessment for Trichloroethylene
3. Rtpoit Ottepinal Revision
October 1981
Thomas, R.; Byrne, M.; Gilbert, D.; Goyer, M. (ADL)
Moss. K. (Acurex Corporation)
8. Performing OrganiMtlon Rept. No.
Pei fanning. Organization Name and Addrest
Arthur D. Little, Inc.
20 Acorn Park
Cambridge, MA 02140
10. Proi«ct/T««k/Work Unit No.
Acurex Corporation
485 Clyde Avenue
Mt. View, CA 94042
11. Contract(C) or Grent(G) No.
(O C-68-01-5949
(C) C-68-01-6017
&. 3taum»liiB Organization Name and Addreu
Monitoring and Data Support Division
Office of Hater Regulations and Standards
U^S. Environmental Protection Agency
Washington, D.C. 20460
IX Type of Report A Period Covered
Final
14.
1ft. Supplementary Notes
Extensive Bibliographies
. Atatrast (Limit 200 wordai
This, report assesses the risk of exposure to trichloroethylene. This study is part of
a program to identify the sources of and evaluate exposure to 129 priority pollutants.
The analysis is based on available information from government, industry, and
technical publications assembled in March of 1981.
The assessment includes an identification of releases to the environment during
production, use, or disposal of the substance. In addition, the fate of trichloro-
ethylene in the environment is considered; ambient levels to which various populations
of humans and aquatic life are exposed are reported. Exposure levels are estimated
and! available data on toxicity are presented and interpreted. Information concerning
aOH of these topics is combined in an assessment of the risks of exposure to trichloro-
etftyiene for various subpopulations.
I Analytle a. Descriptors
Exposure
tTater Pollution
&£r Pollution
fe. IdMlfflen/Opoti-Endod Term*
Eo-llutant Pathways
Ki'sk Assessment
B. COS«I Field/Group Q6F 06T
Effluents
Waste Disposal
Food Contamination
Toxic Diseases
Trichloroethylene
U.S. Environmental Protection Agency
Region HI Information Resource
Center (3PM52)
841 Chestnut Street
Philadelphia, PA 19107
Statement
alease to Public
19. Security Cleis (This Report)
Unclassified
20. Security Clau (TMe Pace)
Unclassified
21. No. of
175
22. Price
S16.00
<»••- 4NSM33U8)
See himvcttofle on ftevem
OPTIONAL FORy 272 (4-77)
(Formerly NTIS-39)
0*ip4ii imcni of CofnniQfcv
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EPA-440/4-85-019
March 1981
(Revised October 1981)
AN EXPOSURE AND RISK ASSESSMENT FOR
TRICHLOROETHYLENE
by
Richard Thomas, Melanie Byrne,
Diane Gilbert, and Muriel Goyer
Arthur D. Little, Inc.
U.S. EPA Contract 68-01-5949
Kenneth Moss
Acurex Corporation
U.S. EPA Contract 68-01-6017
Charles Delos
Project Manager
U.S. Environmental Protection Agency
Monitoring and Data Support Division (WH-553)
Office of Water Regulations and Standards
Washington, D.C. 20460
OFFICE OF WATER REGULATIONS AND STANDARDS
OFFICE OF WATER AND WASTE MANAGEMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
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FOREWORD
Effective regulatory action for toxic chemicals requires an
understanding of the human and environmental risks associated with the
manufacture, use, and disposal of the chemical. Assessment of risk
requires a scientific judgment about the probability cf harm to the
environment resulting from known or potential environmental concentra-
tions. The risk assessment process integrates health effects data
(e.g., carclnogenicity, teratogenicity) with information on exposure.
The components of exposure include an evaluation of the'sources of the
chemical, exposure pathways, ambient levels, and an identification of
exposed populations including humans and aquatic life.
This assessment was performed as part of a program to determine
the environmental risks associated with current use and disposal
patterns for 65 chemicals and classes of chemicals (expanded to 129
"priority pollutants") named in the 1977 Clean Water Act. It includes
an assessment of risk for humans and aquatic life and is intended to
serve as a technical basis for developing the most appropriate and
effective strategy for mitigating these risks.
This document is a contractors' final report. It has been
extensively reviewed by the Individual contractors end by the EPA at
several stages of completion. Each chapter of the draft was reviewed
by members of the authoring contractor's senior technical staff (e.g.,
toxicologists, environmental scientists) who had not previously been
directly involved In the work. These individuals were selected by
management to be the technical peers of the chapter authors. The
chapters were comprehensively checked for uniformity in quality and
content by the contractor's editorial team, which also was responsible
for the production of the final report. The contractor's senior
project management subsequently reviewed the final report in its
entirety.
At EPA a senior staff member was responsible for guiding the
contractors, reviewing the manuscripts, and soliciting comments, where
appropriate, from related programs within EPA (e.g., Office of Toxic
Substances, Research and Development, Air Programs, Solid and
Hazardous Waste, etc.). A complete draft was summarized by the
assigned EPA staff member and reviewed for technical and policy
implications with the Office Director (formerly the Deputy Assistant
Administrator) of Water Regulations and Standards. Subsequent revi-
sions were included in the final report.
Michael W. Slimak, Chief
Exposure Assessment Section
Monitoring & Data Support Division (WH-553)
Office of Water Regulations and Standards
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EXECUTIVE CONCLUSIONS1
Trichloroechylene (TCE) is a synthetic chemical widely used as a
solvent. It is now ubiquitous in the environment, particularly as an
air pollutant. Concern about exposure to TCE stems from its toxicity
and suspected carcinogenicity.
TCE is now produced from 1,2-dichloroethane at a rather steady
level of about 130,000 metric tons per year, a volume perhaps one-half
of the production 10 years ago. Ninety-two percent of the TCE production
is consumed as a degreasing solvent, mostly for cleaning metal, second-
arily for washing undyed fabrics. Recycle of TCE is practiced to some
extent, resulting in total solvent use being perhaps 17% greater than
solvent production and consumption. Four percent of production is con-
sumed as a chemical feedstock, and four percent for other uses including
fungicide. A variety of former uses have been discontinued, such as for
coffee decaffeination and other food and cosmetic uses, and for anesthesia,
dry cleaning, and paint formulation.
The entire TCE production is ultimately released to the environment,
except for the 6% which is consumed as a feedstock or destroyed by in-
cineration. During or following use or reuse, perhaps 79% of production
is released to air, 14% to land, and 1% to ambient waters. Around 2%
of this total release occurs through municipal conveyance or treatment
systems; most of this volatilizes before being discharged to surface
waters.
Environmental partitioning of TCE favors air rather than water;
water concentrations in equilibrium with commonly occurring air concen-
trations would be in the undetectable ng/1 range. Surface water con-
centrations above this level can be expected to volatilize, with half
life often ranging from hours to weeks. In the atmosphere, TCE is
destroyed by photo-oxidation, with a half life of about 1 day.
If TCE were completely stable chemically in water and soil, then
virtually all of the quantity disposed of to land could ultimately be
expected to migrate away from the disposal site, either by volatilizing
into the atmosphere or by leaching into groundwater. However, since
TCE dissolved in water may slowly hydrolyze, with a reported half life
of about 1 year, a substantial amount of degradation might occur over
the years. Whether current disposal technology is capable of containing
TCE until chemical degradation has occurred is, however, not known.
(With respect to kinetics in any medium, it should be noted that more
than three half lives are required to achieve a 90% reduction and almost
seven half lives for a 99% reduction.)
Prepared by EPA Technical Project Officer based in part on program
considerations.
iii
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Ambient environmental data indicates that urban air tends to have
elevated ICE levels. It is detected in surface and groundwater supplies
vich about equal frequency; however, the higher concentrations tend to
be found in groundwater supplies. The effect these levels have on human
health hinges partially on whether or not ICE is carcinogenic, a contro-
versial question due to the existence of some positive indications on
one hand, but lack of unambiguous and consistent results on the other.
Exposure to technical grade ICE has been shown to result in an ap-
parent increase in liver cancer in one strain of mice. The validity of
this finding has been questioned primarily on the basis of high spontaneous
liver cancer rates indigenous to the mouse strain, and the presence of
strongly mutagenic stabilizing chemicals (epoxides) added to technical
grade TCE. Tests with pure TCE on three other species failed to show
liver carcinogenicity; however, one sex of one species showed an increase
in lymph cancer, attributed to an immunity suppressing effect at high
concentrations, rather than a cancer initiating effect. Several other
studies (including one of human epidemiology) failed to detect carcino-
genesis in a variety of species.
TCE is toxic to the liver, kidneys, heart, and nervous system. How-
ever, a criterion derived to prevent such toxicity would be substantially
higher than one intended to reduce cancer risks to negligible levels,
assuming that TCE is as carcinogenic as some of the mouse studies suggest.
For prevention of non-carcinogenic toxicity, the Water Quality Criteria
document sets the threshhold at 800 ug/1, a level which would correspond to
an estimated cancer risk of 3xlO~4. For prevention of more than a 10-5
excess cancer risk, the EPA water quality criterion is 27 ug/1. Thus,
the severity of the environmental TCE problem is dependent on the car-
cinogenic potential of TCE, particularly pure grade TCE.
Environmental exposures to TCE, averaged nationwide, appear to re-
sult primarily from contamination of air, food, and water in descending
order of importance. Considering all three routes, average exposure
through water would be 2-10 percent of the total, depending on the
estimate used for the mean air exposure.
If all carcinogenicity tests yielding negative results are ignored,
and the mouse tests showing the most positive results are linearly extra-
polated to low doses using the EPA Cancer Assessment Group model, then
the magnitude of the nationwide risks would be roughly estimated as
shown below. The assumptions incorporated into such extrapolations
suggest that these predictions be regarded as the maximum risks for
which a plausible argument could be made, rather than the risks which
might actually seem most probable.
iv
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EPA ESTIMATES OF CANCER RISKS FROM ENVIRONMENTAL EXPOSURE BASED ON
AVERAGE NATIONWIDE CONDITIONS2
Nationwide
Average Average Excess Incidence
Route TCE Level • Lifetime Risk (cancers/year)
Ambient Air 0.2-2 yg/m3 10~6 - 10"5 2.5 - 23
Drinking Water 0.5 ug/1 2 x 10~ 0.6
Food 6 ug/day 10~ 4
TOTAL • 11-47 ug/day 10"6 - 10"5 7-28
The ranges of individual risks from exposure via some routes may
differ considerably from the population averages shown above. While the
average drinking water risk is 2x10""?, 0.5% of the EPA nationwide survey
data [NOMS and NOSP (GC-MS) samples] exceed the 27 ug/1 criterion suggested
for protection from more than a 10~5 risk. Moreover, other information
indicates that some groundwater supplies are contaminated with up to
3000 '.ig/1, representing a possible cancer risk of 10~3 for lifetime
exposure. In no case does contaminated fish appear to be a significant
route.
Waterbome routes of exposure are rarely expected to result in non-
cancer related toxicity. Only 1% of all STORET ambient data, and none
of the above mentioned nationwide survey data of drinking water exceed
even one-tenth of the 800 ug/1 non-cancer related safe dose ceiling.
Similarly, current ambient levels appear to pose little hazard to aquatic
life, since toxicity has not been reported at less than 2,000 and 22,000
ug/1 for salt and freshwater organisms, respectively.
EPA's Office of Water Regulations and Standards has concluded that:
(1) The benefits of reducing TCE exposure are partially
dependent on the carcinogenic potency attributed to
TCE, and are thus currently not completely certain.
(2) On the average, exposure to TCE is primarily through
air and food, with waterborne routes contributing
possibly 2-10 percent. In some instances, however,
TCE concentrations in groundwater may attain levels
possibly associated with substantial health risks.
Table 7-1 in the following report depicts individual excess cancer risks
for specific environmental situations, whereas the values here are intended
to reflect excess cancer risks associated with average nationwide condi-
tions. Hence, the two tables are complementary.
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(3) Due co rapid volatilization, wastewater borne TCE may
affect air as well as water media. Volatilization
from water does not appear to be one of the major
sources of atmospheric TCE, however.
(4) The fate of TCE disposed of on land is not well
enough understood to know whether it may eventually
enter the environment by volatilizing or leaching.
Nevertheless, its gradual rate of degradation appears
to place some limit on the distance it can travel in
groundwater. The bulk of TCE disposed of by recycle
or incineration appears not to enter the environment.
Notes on Derivation of TCE Risks:
Unit Risk (Dose-Response)
Lifetime risk is based on NCI mouse study (as reported by CAG and
the Water Quality Criteria document):
1.26 x 10" lifetime cancer risk/(mg/kg-day) TCE intake.
For a 70 .kg person:
55 yg/day TCE intake corresponds to 10~ risk.
Nationwide incidence is based on 70 year average lifetime for 220
million persons in U.S.
Population Risk
Air; The inhaled volume is 20 m /day. Two estimates for the
mean exposure are based on:
(1) EPA OAQPS modeling: 34.5 million person-ug/m exposure
for 159 million persons implies 0.22 ug/nr mean exposure
(Anderson jst al. 1980).
(2) Lillian e^ al. (1975) data for 8 cities: mean
concentration 2 yg/nr.
Drinking Water; The ingested volume is 2 I/day. The mean
concentration from NOMS is approximately 0.5 yg/1 re-
gardless of whether undetected levels are assumed to
be a minimum of zero or a maximum of just below the
detection limit. NOSP (GC-MS) data support this esti-
mate. It may be noted that heating is likely to drive
off the volatile organics; 2 I/day may overestimate
the unheated water intake.
vi
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Food; Data from McConnell a_t al. (1975), projected to various
classes of food in a standard diet, as described in
Chapter 5.
Uncertainties in the exposure estimates arise from several factors, in-
cluding (a) very small sample sizes on which the air, water, and food
projections are based, (b) possible sampling biases (for example, the
air data is applicable to outdoor urban air rather than either rural
or indoor air), (c) possible inaccuracies in laboratory methods, (d)
uncertainties in the effects of food and beverage preparation on ICE
content, and (e) on other minor biases such as ignoring small differences
between the uptake efficiencies of inhalation and ingestion. In addition
to the uncertainties relating to exposures, there is considerable uncer-
tainty regarding the validity of extrapolating dose-response data from
laboratory animals to humans.
(References listed in Chapters 4 and 5.)
vii
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TABLE OF CONTENTS
PAGE
EXECUTIVE CONCLUSIONS ill
LIST OF TABLES . xiii
LIST OF FIGURES xv
ACKNOWLEDGMENTS xvii
1.0 TECHNICAL SUMMARY 1-1
2.0 INTRODUCTION 2-1
3.0 MATERIALS BALANCE ' 3-1
3.1 Introduction 3-1
3.2 Summary 3-1
3.3 Production of Trichloroethylene 3-4
3.3.1 Production of Trichloroethylene and Tetra- 3-5
chloroethylene
3.3.2 Trichloroethylene Releases: Production, 3-5
Storage and Fugitive
3.3.3 Publicly Owned Treatment Works (POTWs) 3-9
3.3.4 Transportation-Related Accidents Involving 3-10
Trichloroethylene
3.3.5 Inadvertent Sources of Trichloroethylene Emissions 3-10
3.3.5.1 Production of Other Chlorinated 3-10
Hydrocarbons
3.3.5.2 Chlorination of Drinking Water and 3-13
Wastewater
3.4 Uses of Trichloroethylene 3-13
3.4.1 Present Use Patterns 3-13
3.4.2 Degreasing Operations 3-16
3.4.2.1 Cold Cleaning 3-20
3.4.2.2 Open-Top Vapor Degreasing 3-20
3.4.2.3 Conveyorized Vapor Degreasing 3-22
3.4.2.4 Fabric Scouring 3-22
3.4.3 Emissions from Minor Applications 3-24
3.4.4 Discontinued Miscellaneous Uses 3-24
3.5 Mismanagement of Trichloroethylene 3-26
3.5.1 Selected Damage Incidents 3-26
3.5.2 Cumulative Emissions 3-27
References 3-31
4.0 DISTRIBUTION IN THE ENVIRONMENT 4-1
4.1 Introduction 4-1
4.2 Trichloroechylene Detected in the Environment and in
Other Media
ix
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TABLE OF CONTENTS (cont'd.)
PAGE
4.3 Environmental Fate of Trichloroethylene 4-12
4.3.1 Atmospheric Fate 4-12
4.3.2 Fate in Water 4-15
4.3.2.1 Volatilization 4-15
4.3.2.2 Hydrolysis 4-17
4.3.2.3 Photolysis 4-17
4.3.2.4 Biodegradation 4-17
4.3.2.5 Sorption/Desorption 4-17
4.3.3 Fate in Soil 4-18
4.3.3.1 Transport and Volatilization 4-18
4.3.3.2 Decomposition 4-18
4.3.4 Other Fate Processes 4-20
4.3.4.1 Waste Materials 4-20
4.3.4.2 Decomposition during Welding 4-23
4.4 Environmental Fate Modelling 4-23
4.4.1 Overview 4-23
4.4.2 Equilibrium Model 4-23
4.4.3 EXAMS 4-27'
4.5 Summary 4-31
References 4-33
5.0 EFFECTS AND EXPOSURE—HUMANS 5-1
5.1 Human Toxicity 5-1
5.1.1 Introduction 5-1
5.1.2 Metabolism and Bioaccumulation 5-1
5.1.2.1 Absorption and Distribution 5-1
5.1.2.2 Biotransformation and Elimination 5-2
5.1.3 Human and Animal Studies . 5-5
5.1.3.1 Carcinogenicity 5-5
5.1.3.2 Mutagenicity 5-8
5.1.3.3 Teratogenicity 5-9
5.1.3.4 Other Toxic Effects 5-10
5.1.4 Summary 5-11
5.1.4.1 Ambient Water Quality Criterion - 5-11
Human Health
5.1.4.2 Trichloroethylene Relation to Hunan Risk 5-11
5.1.5 Estimation of Human Dose-Response Relationships 5-13
for Cancer
5.1.5.1 Introduction 5-13
5.1.5.2 Calculation of Human Equivalent Doses 5-15
5.1.5.3 Estimation of Human Risk Relationships 5-15
5.1.5.4 Other Considerations 5-18
x
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TABLE OF CONTENTS (cont'd.)
5.2 Human
5.2.1
5.2.2
5.2.3
5.2.4
Exposure
Introduction
Exposure Scenarios
5.2.2.1 Populations Exposed through Inhalation
5.2.2.2 Populations Exposed through Ingestion
of Contaminated Drinking Water and
Foodstuffs
5.2.2.3 Populations Exposed through Dermal Contact
Exposure Estimates
5.2.3.1 Air
5.2.3.2 Water
5.2.3.3
Summary
Food
References
6.0 EFFECTS AND EXPOSURE— BIOTA
6.1 Effects on Biota
6.1.1 Introduction
6.1.2 Freshwater Organisms
6.1.2.1 Acute Effects
6.1.2.2 Chronic Effects
6.1.3 Marine Organisms
6.1.3.1 Acute Effects
6.1.3.2 Chronic Effects
6.1.4 Other Studies
6.1.5 Summary
6.2 Biological Fate and Bioaccumulation
6.2.1 Aquatic Biota
6.2.1.1 Fish
6.2.1.2 Birds and Mammals
6.2.1.3 Invertebrates
6.2.1.4 Plants
Terrestrial Biota
6.2.2.1 Vertebrates
6.2.2.2 Plants
Biomagnification in the Food Chain
Summary
6.3 Exposure to Biota
6.3.1 Introduction
6.3.2 Monitoring Data
6.3.3 Ingestion Exposure
6.3.4 Fish Kills
6.3.5 Summary
References
6.2.2
6.2.3
6.2.4
PACE
5-19
5-19
5-20
5-20
5-20
5-22
5-22
5-22
5-23
5-23
5-23
5-27
6-1
6-1
6-1
6-1
6-1
6-2
6-3
6-6
6-6
6-6
6-6
6-7
6-8
6-8
6-8
6-8
6-9
6-9
6-9
6-10
6-11
6-11
6-12
6-12
6-12
6-13
6-13
6-13
6-15
xi
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TABLE OF CONTENTS (cont'd.)
PAGE
7.0 RISK CONSIDERATIONS 7-1
7.1 Human Risk 7-1
7.2 Risk to Aquatic Organisms 7-4
APPENDIX A A-l
APPENDIX B B-l
APPENDIX C C-l
APPENDIX D D-l
APPENDIX E E-l
APPENDIX F F-l
APPENDIX G G-l
APPENDIX H H-l
xii
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LIST OF TABLES
TABLE ?AGE
3-1 Trichloroechylene Environmental Releases: Production 3-5
3-2 Trichloroethylene Environmental Releases from 3-11
Inadvertent Sources
3-3 Trichloroethylene Materials Balance: Use 3-14
3-4 Selection of Chemical Products Containing 3-17
Trichloroethylene
3-5 Trichloroethylene Emissions: Degreasing Operations 3-19
3-6 Cumulative Releases of Trichloroethylene from Degreasing 3-29
Operations
4-1 Trichloroethylene in Ambient Waters 4-2
4-2 Weight/Weight Comparison of Concentrations of Trichloro- 4-3
ethylene in Different Media
4-3 Concentration of Trichloroethylene Detected in Human 4-4
Tissue
4-4 Concentrations of Trichloroethylene Detected in Food 4-5
from the U.K.
4-5 Selected Measurements of Trichloroethylene Concentrations 4-7
in Air
4-6 Compilation of Measurements of Trichloroethylene Con- 4-9
centrations in Water
4-7 Measured Evaporation Rates for Trichloroethylene 4-16
4-8 Composition of Soils Used in Study of Trichloroethylene 4-19
Fate in Soil
4-9 Fate of Trichloroethylene Applied to a Soil Column in 4-19
the Laboratory
4-10 Trichloroethylene Adsorption onto Sludge-Data Summary 4-22
4-11 Trichloroethylene Concentrations at Various Stages of 4-24
Wastewacer Treatment
4-12 Data Used in Level II Fugacity Calculations 4-24
xiii
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LIST OF TABLES (cont'd.)
TABLE PAGE
£-13 Estimated Trichloroethylene Concentrations in Air, Water 4-26
and Soil Determined by Fugacity Calculations
4-14 Parameters for Trichloroethylene Used in EXAMS Analysis 4-28
4-15 The Fate of Trichloroethylene in Various Generalized 4-29
Aquatic Systems
4-16 Estimated Steady-State Concentrations in Various Generalized 4-30
Aquatic Systems Resulting from Continuous Discharge of
Trichloroethylene at a Rate of 10 kg/hr
5-1 Estiaated Non-Occupational Exposure to Trichloro- 5-14
ethylene via Inhalation
5-2 Estimated Occupational Exposure to Trichloroethylene 5-16
via Inhalation
5-3 Estimated Trichloroethylene Exposure by Ingestion: 5-21
Amounts, Concentrations, and Intake by Source
5-4 Summary of Estimated Exposure to Trichloroethylene 5-24
5-5 Estimated Trichloroethylene Exposure by Ingestion: 5-25
Amounts, Concentrations, and Exposure by Source
5-6 Summary of Estimated Exposure to Trichloroethylene 5-26
6-1 Acute Toxicity of Trichloroethylene for Fresh Water 6-2
Fish and Invertebrates
6-2 Results of Flowthrough Studies of Chronic and Acute &"*
Toxicity of Trichloroethylene for the Fathead Minnow
6-3 Toxicity of Trichloroethylene for Salt Water Fish 6-5-
7-1 Estiaated Levels of Human Exposure and Excess Individual 7-3
Lifetime Probability of Tumor Incidence Due to Exposure
to Trichloroethylene
xiv
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LIST OF FIGURES
FICUT.E PAGE
3-1 U.S. Trichloroechylene Materials Balance, 1978 3-2
3-2 Environmental Releases from Trichloroechylene and 3-7
Tecrachlorethylene Production by Chlorination
3-3 Environmental Releases from Trichloroechylene and 3-8
Tetrachloroethylene Production by Oxy-Chlorinaeion
3-4 Domestic Production of Trichloroechylene 3-15
3-5 Degreaser Flow Diagram 3-18
3-6 Geographic Distribution of Cold Cleaning Operations 3-21
3-7 Geographic Discribution of Vapor Degreasing Operations 3-23
3-8 Geographic Distribution of Fabric Scouring Operations 3-25
3-9 Disposition of Trichloroethene Consumed in Solvent 3-20
Degreasing
4-1 Major Pachways of Trichloroechylene in che Environmenc 4-13
4-2 Absorption Spectra of Trichloroethylene .4-14
4-3 Correlation Between Trichloroethylene in Dry Solids and 4-21
that in Settled Wastewater from Sewage Treatment
4-4 Correlation Between Trichloroethylene in Wet Sludge and 4-21
that in Untreated Sewage
4-5 Plot for Maximum Trichloroethylene Sorption on Cried 4-22
Sludge Solids
4-6 Intermedia Flux of TCE and Media Concentrations Based 4-26
on Air Emissions and Fate Processes—Estimates Based
on Dynamic Partitioning Model
5-1 Metabolism of Trichloroechvlene in Animals and Man 5-3-
xv
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ACKNOWLEDGEMENTS
The Arthur D. Little, Inc. task manager for this study was Richard G.
Thomas. Major contributors to this report were Melanie Byrne and
Kathy Saterson (Biological Effects), Diane Gilbert (Human Exposure)
and Muriel Goyer (Human Effects). In addition, Kate Scow did the EXAMS
analysis and contributed to Biological Effects; John Ostlund, Alan
Eschenroeder, and Joseph Fiksel estimated dose/response parameters, and
Jane Metzger and Nina Green edited and documented the report.
The materials balance for trichloroethylene (Chapter 3.0) was
provided by Acurex, Inc., produced under contract 68-01-6017 to the
Monitoring and Data Support Division (MDSD), Office of Water Regulations
and Standards (OWRS), U.S. EPA. Kenneth Moss was the task manager for
Acurex, Inc. Patricia Leslie was responsible for report oroduction.
Charles Delos, MDSD, was the project manager at EPA.
xvii
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1.0 TECHNICAL SUMMARY
The Monitoring and Daca Support Division, Office of Water Regulations
and Standards, the U.S. Environmental Protection Agency, is conducting an
ongoing program to assess the risk associated with exposure to 129 pri-
ority pollutants in the environment. This report assesses the exposure
and risk associated with trichloroethylene (TCE).
1.1 MATERIALS BALANCE
Trichloroethylene is a high-vapor-pressure organic solvent, used
almost exclusively (>90%) in degreasing operations. The chemical has
become pervasive in the environment due to fugitive emissions during
production, use, and disposal.
Production of trichloroethylene has declined sharply from 206,000
kkg in 1973 to 136,000 kkg in 1978, mostly in response to declining
demand and improved solvent recovery. About 90% of the total used is
estimated to be discharged to the environment, and degreasing operations
account for almost all the releases of this amount. Environmental
releases are primarily to air due to evaporation of the chemical. Dis-
charges to water account for much less of the total and the amount
disposed of on land is also relatively small. However, land discharges
may pose significant problems for groundwater quality.
Only three sites in the U.S. manufacture the chemical, all located
along the Gulf Coast. Releases from production are only a small part of
the total released each year.
1.2 FATE AND DISTRIBUTION IN THE ENVIRONMENT
1.2.1 Distribution of Trichloroethylene in the Environment
Trichloroethylene appears in all environmental media - air, water
(including groundwater), and soil. Concentrations detected in the
atmosphere range from a background of 27-100 ng/m^ to about 1.5 mg/m^ '
in the vicinity of TCE production sites. Concentrations found in sur-
face water range from none to 188 ug/1. When detected, however,
concentrations are generally on the order of 1-10 ug/1. In groundwater,
concentrations up to 35000 ug/1 have been detected, but monitoring sur-
veys indicate concentrations to be mostly in the.<1-100 ug/1 range.
Data on only a few soil samples were found. These showed soil concen-
trations between none detected and <10 ug/kg (dry weight). Data con-
cerning concentrations in sediments are too few to indicate specific
sorption characteristics, although TCE does sorb and has been found in
sediments.
1-1
-------
1.2.2 Environmental Face of Trichloroethylene
ICE is highly volatile. The hair-life of trichloroechylene in
surface waters is estimated to be on the order of a few hours to a few
days, depending upon the characteristics of the water body. TCE will
also volatilize from soil if exposed to the air, although estimates of
the volatilization rate are imprecise. The process appears to occur
up to ten times more slowly from soil than from water of a similar depth.
The ultimate disposition of TCE appears to be atmospheric photo-
oxidation. The half-life in the atmosphere due to photooxidation is
estimated to be a day or so, possibly one-half day to a couple of days.
TCE does not undergo other chemical fate processes to any appreciable
degree, although chemical degradation in groundwater may be significant,
with a half-life on the order of a year. On the basis of this informa-
tion, the fate ox TCE is expected to be destruction by atmospheric
photooxidation following direct emission or volatilization from water
or soil.
Models of environmental fate indicate that changes in ambient
concentrations are linearly dependent upon changes in environmental
loadings. The EXAMS model indicates that most TCE is volatilized;
transformation and bioaccumulation will not reduce water concentration
significantly. These results are consistent with observations regarding
fate.
1.3 RISKS TO HUMANS
1.3.1 Human Effects
Oral administration of TCE was carcinogenic in B6C3F1 mice including
a 52% incidence of hepatocellular carcinoma in male mice at a level of
1170/mg/kg bw. Some controversy exists, however, regarding the design
of this study. Repeated dermal application and initiation-promotion
studies with Ha:ICR Swiss mice were negative and intubation of 1.5 mg
TCE/mouse/week produced no tumors in liver, lungs or stomach in this
strain. Mo carcinogenic activity was found in Osborne-Mendel rats given
TCE by gavage; however, survival was poor, reducing the ability to detect
a carcinogenic response in this study.
Negative results were reported in a dominant lethal assay with rats
exposed by inhalation to 1614 mg/m^ TCE for 9 months, and exposure of
mice (1614 mg/m^) and rats (9684 mg/m^) during gestation gave no indi-
cation of fetotoxic or teratogenic effects. Positive mutagenic effects
have been reported in a mammalian cell transformation assay and weak
responses in bacterial and yeast test systems, but only if microsomal
activation was provided.
The predominant toxic manifestation of TCE exposure in man is
depression of the central nervous system. Transient increases in
serum transaminases (an indication of liver toxicity) have also been
1-2
-------
reported, but boch these effects are reversible upon removal from the
source. Intolerance to alcohol is a well-documented symptom of repeated
TCE exposure. High acute doses have produced cardiac arrhythmias and
death by ventricular fibrillation and cardiac arrest. The lowest reported
oral lethal dose in man is 50 mg TCE/kg body weight.
1.3.2 Human Exposure to Trichloroethylene
Humans can be exposed to TCE by the presence of TCE in all environ-
mental media - air, water, and soil - and through drinking water and
foodstuffs. Exposures have been estimated based upon activity and
location. Inhalation exposures range from 0.0006 to 14 tag/day for
non-occupational activities and up to 5800 nig/day for occupational
activities. Ingestion via foodstuffs and water has been estimated at
_<_ 0.0006 to 6 mg/day. Thus ingestion of water (2 liters per day)
contaminated at the maximum estimated concentration of TCE found in
water (i.e., 3 mg/1) would contribute 6 mg/day to the total body burden
of TCE, an amount less than one-half that possible from inhalation at
the upper bound of non-occupational inhalation exposure (i.e., 14 mg/day),
but could potentially exceed the lower bound of non-occupational inhala-
tion' exposure (0.0006 mg/day) by several thousand-fold. However, findings
of the maximum estimated TCE concentration in water are an uncommon event,
and the generally observed levels of TCE in drinking water would result in
intakes (0.004 tng/day) substantially lower than those possible from
non-occupational inhalation exposure, but roughly comparable to the
estimated upper limit for intake from food (0.006 mg/day).
1.3.3 Risk Considerations for Humans
Exposure levels to individuals have been estimated for different
exposure conditions. Dose/response extrapolations based on three models
have been applied to these exposure levels using data from one positive
study in B6C3F1 mice to estimate risk levels. Risk .estimates of excess
individual lifetime tumor incidence associated with TCE intakes due to
inhalation range from 4 x 10~8 to 8 x 10~4, corresponding to background
TCE concentrations in air and high ambient concentrations near users,
respectively. Estimated excess individual lifetime cancer risk due to
continuous lifetime consumption of drinking water contaminated at the
average observed TCE levels Is in the <10"7 to 10~6 range. At the high-
est TCE concentrations observed in drinking water, estimated excess
individual lifetime cancer risk levels are =10~3.
Considerable controversy exists regarding the most appropriate
method for extrapolating human equivalent doses from animal data. Due
to this uncertainty, the range of risk estimated by the various extra-
polation models may under- or overestimate the actual risk to man.
Overestimation appears more likely due to the conservative assumptions
utilized in the calculation of human equivalent doses.
1-3
-------
Other chan carcinogenic risks, acute human exposure to ICE is ot
concern only at high exposure concentrations. Inhalation of 800 mg/m3
ICE for 2 hours can depress the central nervous system, while ingestion
of 150 ml TCE can result in acute renal failure and cardiovascular
damage. Data on chronic human exposure to TCE are not available. No-
effect levels ranging from 540 to 2050 mg/m-* have been established for
laboratory animals exposed for periods up to 6 months.
1.4 RISKS TO AQUATIC BIOTA
1.4.1 Toxic Effects of Tricholoethylene to Aquatic Biota
Under laboratory conditions TCE has been shown to be lethal to fish
and other aquatic organisms, and to affect such functions as equilibrium,
respiration, and reproduction. Acute effects levels for fish are
40-79 mg/1 .(LCso). One test for chronic effects showed a 48-hour LC5Q
for Daphnia of 85 mg/1 and no effect during a chronic test at 10 mg/1.
For 24 hr - 96 hr tests, the LCso for fathead minnows was 22 - 23 mg/1
and LCgo's are in the same range: 16 - 100 mg/1. Algae showed toxic
effects at 8 mg/1.
Results of the studies cited show most effects levels to be in the
10 - 100 mg/1 range in most freshwater and marine fish.
1.4.2 Exposure of Aquatic Biota to Trichloroethylene
Ambient water concentrations of TCE seem to fall in the not
detected to 10 ug/1 range, although some concentrations in particular
areas are higher. The highest reported was 5.3 mg/1 in the vicinity
of a TCE manufacturing plant. Significant exposures to TCE might,
therefore, occur in extremely localized areas; however, most aquatic
biota will experience little or no exposure. The high volatility of
.TCE also indicates that any high concentrations are not likely to
persist for periods of longer than hours or days unless direct inputs
at particular locations continue.
1.4.3 Risk Considerations for Aquatic Biota
Chronic and acute toxlcity levels of tricholorethylene for aquatic
biota are greater than 10 mg/1. The highest reported ambient concentra-
tion was 5.3 mg/1 in the vicinity of a manufacturing plant. Other
detected concentrations are much lower; consequently, biota will not be
exposed to levels that overlap with those causing toxic effects.
On the basis of these considerations, the risk to aquatic biota due
to trichloroethylene in ambient waters is determined to be negligible.
1-4
-------
2.0 INTRODUCTION
The Office of Water Regulations and Standards, Monitoring and
Data Support Division, the U.S. Environmental Protection Agency, is
conducting a program to evaluate the exposure to and risk of 129
priority pollutants in the nation's environment. The risks to be
evaluated include potential harm to human beings and deleterious
effects on fish and other biota. The goal of the task under which this
report has been prepared is to integrate information on cultural and
environmental flows of specific priority pollutants and estimate the
risk based on receptor exposure to these substances. The results are
intended to serve as a basis for developing suitable regulatory strategy
for reducing the risk, if such action is indicated.
This report provides a brief, but comprehensive, summary of the
production, use, distribution, fate, effects, exposure, and potential
risks of crichloroethylene.
The report is organized as follows:
Chapter 3.0 presents a materials balance for crichloroethylene
that considers quantities of the chemical consumed or produced
in various processes, the form and amount of pollutant released
to the environment, the environmental compartment initially
receiving it, and, to the degree possible, the locations and
timing of releases.
Chapter 4.0 describes the distribution of trichloroethylene in
the environment by presenting available monitoring data for
various media and by considering the physicochemical and
biological fate processes that transform and transport
the chemicals.
Chapter 5.0 describes the available data concerning the
toxicity of trichloroethylene for humans and laboratory
animals and quantifies the likely level of human exposure
via major known exposure routes.
Chapter 6.0 considers toxicological effects on and exposure
to biota, predominantly aquatic biota.
1 Chapter 7.0 compares exposure conditions for humans and
other biota with the available data on effects levels from
Chapters 5.0 and 6.0. The risks presented by various
exposures to the trichloroethylene are estimated.
2-1
-------
Appendices A-G present core detailed information supporting
materials balance estimates in Chapter 3.0. Appendix H
discusses the procedure for estimating the volatilization
rates of trichloroethvlene.
-------
3.0 MATERIALS BALANCE
3.1 INTRODUCTION'
This chapter presents an environmental materials balance for
crichloroethylene.
As matter is neither created nor destroyed in chemical trans-
formations, the total mass of all materials entering a system equals
the total mass of all materials leaving that system, excluding those
materials the system accumulates or retains. From the perspective
of risk analysis, a materials balance may be performed around any
individual operation chat serves to identify a specific population
at risk (e.g., process water discharges creating ground water con-
tamination). An environmental materials balance, therefore, consists
of a collection of materials balances, each of which is directed
to a specific source and sink within the environment.
The scope of this report has been limited to a review of both
published and unpublished data concerning the production, use, and
disposal of trichloroethylene within the United States. Available
literature has been critiqued and compiled in a single document to
present an overview of major sources of environmental release of
trichloroethylene and fully annotated tables to aid data evaluation.
3.2 SUMMARY
The flow of trichloroethylene through the environment is shown
in Figure 3-1. Trichloroethylene is found in all media of the
environment. Available literature indicates it is solely man-made.
Like other low molecular-weight chlorinated hydrocarbons, trichloro-
ethylene has a relatively high vapor pressure and low water solubility
and thus tends to partition toward the atmosphere.
Historically, contamination of groundwater supplies has been tied
to disposal practices. As discussed in Section 3-5, trichloroethylene
pollution of groundwater and drinking water supplies appears largely
attributable to migration and leaching of the chemical from unlined
or improperly lined landfills, settling ponds, old dredge pits, open
fields, and old industrial sludge oits. Documented incidents of envi-
ronmental damage resulting from improper management of trichloroethylene-
containing wastes are listed in Appendix G. In many cases, the specific
source or generator of the waste is unknown or not easily identified.
However, in the cases where a particular point source can be isolated,
metal degreasing operations have been the primary contributors of the
trichloroethylene wastes.
3-1
-------
3i p*C* Sources
£3,000
Direct ChloHnaiton ^^
57.000
Ijnoorts 1
Indirect Sources
Cnlorlnation of
'•a:er SUSP lies
Manufacture of Vinyl
Monomer
Manufacture of
Tetrschloroethylene
SCT.S
^•M^H
Uses
r.nrof
IS.OCC *~
3.300
PVC Chain Transfer
5.000
Cold Cleaning v 1 _
30.000 (3?.000)D j a
Ooen Top Vaoor
56.000 Uey'eal"l
-------
To assess and understand the impact of crichloroethylene in terms
of demonstrated and potential ground water degradation, estimates of
the cumulative amounts of trichloroethylene released to air, water, and,
most importantly, land over the period of 1954-1978 are presented.
Table 3-6 presents a summary of cumulative releases to land and water
based on a simplified scenario in which only losses from degreasing
operations are considered. As shown, an estimated 730,000 kkg of tri-
chloroethylene were dumped on land and an additional 320,000 kkg released
to water during the study period. This represents only the "worst case"
accumulation over the past 25 years; indeed, an indeterminate yet sig-
nificant amount will have volatilized from surface waters or open
impoundments during this time. Atmospheric degradation is the primary
sink for trichloroethylene. It is destroyed rapidly in the atmosphere.
(See Chapter 4.0.)
Section 3.3 of this chapter investigates production of trichloro-
ethylene, from either direct or inadvertent sources. Trichloroethylene
is manufactured (as a coproduct with tetrachloroethylene) by either
chlorination or oxy-chlorination of 1,2-dichloroethane or other C2
chlorinated hydrocarbons. All of the 136,000 kkg of trichloroethylene
produced in the United States during 1978 was from 1,2-dichloroethane
based processes; production sites were limited to Dow Chemical Corp.,
Freeport, Texas; Ethyl Corp., Baton Rouge, Louisiana; and PPG Industries,
Lake Charles, Louisiana. (See Table 3-1.) Prior to 1978, 8 percent of
U.S. trichloroethylene production was via an acetylene-based process,
which has been abandoned due to increasing feedstock costs.
Few data are available regarding emissions of trichloroethylene
during production. Major point sources of atmospheric emissions are
neutralization and drying vents and distillation vents; an estimated
280 kkg were dispersed to the air from trichloroethylene manufacture
during 1978. Process discharges to land and water were negligible.
(See Table 3-1.)
The second part of Section 3.3 is a discussion of inadvertent
sources of trichloroethylene. Trichloroethylene emissions originate
from the production of other chlorinated hydrocarbons—specifically
during vinyl chloride monomer (VCM) and tetrachloroethylene production.
However, since much of the waste tars are recyclable (or incinerated)
and water emissions are negligible, trichloroethylene discharges from
these sources are not significant. (See Table 3-2.)
Another possible inadvertent source of chlorinated hydrocarbons
might be chlorination of drinking water and wastewater. Trichloroethy-
lene has been identified in drinking water supplies in the ug/1 range;
however, the source of such chlorinated organic chemicals cannot be
readily identified (e.g., whether they are in the raw water prior to
treatment or introduced as a result of chlorination). For purposes
of this materials balance, it was assumed that a negligible amount of
trichloroechylene was created and discharged to the environment by
water chlorination.
3-3
-------
Trichloroethylene loading to POTWs varies widely in different
*1"?0- Of che estimated 1,020 kkg trichloroethvlene entering
calculations indicate that approximately 85 percent is lost to
air and 15 percent is discharged to water. (See Section 3.3.3.)
and 1«reS?nt^USe pa"erns« in Particular crichloroethylene consumption
and loss in degreasing operations, are presented in Section 3.4. In
response to declining demand and improved solvent recovery, production
?LC^ °eChylene dr°PPed sharply from 206,000 kkg in 1973 to
136,000 kkg in 1978. Historically, however, over 90 percent of the
trichloroethylene domestic supply has been consumed in degreasing
operations. Minor uses of trichloroethylene, which include the produc-
tion of fungicides, cleaning fluids and adhesives, represent only 4 per-
cent of the total domestic consumption; the remainder (approximately
4 percent) is used as a chain terminator in polyvinyl chloride production.
for
Trichloroethylene is one of the most versatile solvents used fc
degreasing operations. Because of its low boiling point (relative
to water;, strong solvent properties, and, until recently, relatively
xow cost, trichloroethylene has been employed in an estimated 160 000
operations annually. This widespread use of trichloroethvlene results
in an estimated annual loss of 120,000 kkg from degreasing operations,
either as process emissions or as waste solvent. As shown in Table 3-3
use of trichloroethylene in fungicides, adhesives, and cleaning fluids '
represent .5 percent of atmospheric emissions', whereas degreasing opera-
tions represent 95 percent of the total. Moreover, degreasing operations
represent virtually 100 percent of all discharges to Jnd ind wa?er
disposal of trichloroethylene within the United States.
Available literature has been critiqued and compiled in this
chapter to present an overview of major sources of environmental release
of trichloroethylene and fully annotated tables to aid data evaluation.
Data collection, sources of information, and problem areas are reviewed
in Sections 3.3 through 3.5. The discussion of the fate and transport
of trichloroethylene within air, soil, and water environmental compart-
ments was limited to a review of damage incidents resulting from
improper disposal of trichloroethylene-bearing wastes and an estimate of
cummulative environmental releases of trichloroethylene from degreasing
operations over the period 1954-1978. (See Section 3.5.)
3.3 PRODUCTION OF TRICHLOROETHYLENE
First synthesized by Fisher in 1864, trichloroethylene was not
manufactured in the United States until 1925. Demand for trichloroethy-
lene increased with improvements in metal degreasing techniques in the
1920rs and with the growth of the dry-cleaning industry during the 1930's.
Recently, however, trichloroethylene production has declined significantly
as a result of its suspected carcinogenicity and contribution to air
pollution.
3-4
-------
3.3.1 Production of Trichloroechvlene and Tetrachloroethylene
Trichloroechylene, along with coproduct tecrachloroethyiene, is
produced by either chlorinacion or oxy-chlorinacion of 1,2-dichloro-
echane or other Ci chlorinated hydrocarbons (including waste streams).
All of the 136, 005 kkg of trichloroethylene produced in the United States
during 1978 was from 1,2-dichloroethane-based processes. Prior to 1978,
8 percent of U.S. trichloroethylene production was via an acetylene-based
process, which has been abandoned due to increasing feedstock costs
(SRI 1979). Table 3-1 summarizes production and emission data for
trichloroethylene manufacture.
The reaction for direct chlorination of 1,2-dichloroethene to
tri- and tetrachloroethylene is:
2C1CH9CH,C1 + 5C1 - > C12C=CHC + C12C=CC12 + 7HC1
This process is discussed in more detail in Appendix A. Figure 3-2
represents a simplified diagram of the emissions from production
by chlorination.
Tri- and tetrachloroethylene may also be produced by oxy-chlorination
of 1,2-dichloroethene:
5C1CH2CH2C1 + 3C12 + 402 -^-> C12C=CC12 -I- 4C12C=CHC1 -I- 8H20
This process is discussed in more detail in Appendix B. Figure 3-3
represents a simplified diagram of the environmental releases from
production by oxy-chlorination.
3.3.2 Trichloroethvlene Releases: Production, Storage and Fugitive
Emissions
Few data are available regarding releases of trichloroethylene
during production. Major point sources of atmospheric trichloroethy-
lene emissions are neutralization and drying vents and distillation
vents. It is estimated that 0.51 kg trichloroethylene/kkg trichloro-
ethylene produced are discharged as process emissions, 0.81 kg/kkg
emitted from storage facilities, and 0.75 kg/kkg as fugitive emissions
(EPA 1980e). Based on the 136,000 kkg trichloroethylene produced in
1978 (USITC 1979), a total of 280 kkg are dispersed to the atmosphere
during trichloroethylene manufacture from process, storage and fugitive
sources. (See Table 3-1.)
Neutralization is the predominant method of treatment of trichloro-
ethylene process wastes. All three of the producing plants discharge
to surface waters; two report secondary treatment (e.g., aerated lagoons
or activated sludge) and one reports primary treatment only. Assuming
total wastewacer production of 0.42 kkg H 30 /kkg product (Catalytic 1979),
total trichloroethylene production of 136,000 kkg (USITC 1979), and an
average trichloroechylene concentration of 6580 ug/1 (Catalytic 1979),
3-5
-------
Table 3-1. Trichloroetliylene Envirunincntal Releases: Production, 1978 (kky/yr)
Company and Location
Dow Chemical Corp.
Kreeport, TX
Ethyl Corp.
Baton Rouge, LA
PPG Industries
Lake Charles, LA
TOTALS
a b
Process Capacity
DC 68,000
DC 20 .000
91 ,000
OXY
179,000
c
Production
52,000
15,000
68,000
136,000
Releases
Aird Land6 Water f
110 neg neg
30 ne
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Table 3-2. Trichloroethylene Environmental Releases from Inadvertent Sources, 1978 (kkg/yr)
Source
Air
Discharges
Aqueous
Solid
Manufacture of 1,2-Dichloroethane by
the Balanced Process
Production of Tetrachloroethylene
Diamond Shamrock Corp.
Deer Park, TX
Chlorination of Drinking Water and Wastewater
neg«
12a
neg1
UJ
I
a)
Based on 29 kg "heavy" chlorinated organic material generated/kkg EDC produced (Lunde, 1965), 5.1 x 106 kkg
EDC produced by balanced process, approximately 4% non-recyclable tars in heavy material, and 0.2%
trichloroethylene by weight in tars (EPA, 1975a). If incinerated, assume 99.9% combustion efficiency. The
remainder of the heavy stream is presumed recycled. At 3.6% trichloroethylene (Lunde, 1965), «%^5200 kkg of
trichloroethylene would be recycled, to carbon telrachloride/tetrachloroethylene production.
b) Based on 0.11 kg trichloroethylene emitted from neutralization and drying vent/kkg tetrachloroethylene produced
by direct chlorination of 1,2-dichloroethane, and 0.056 kg/kkg from distillation vent (EPA, 1977d). Capacity for
this plant: 75xl03 kkg tetrachloroethylene; production at 63% of capacity. (USITC, 1979; EPA, 1979d).
c) Based on National Organic Monitoring Survey data (EPA, 1977c). POTWs considered a throughput, rather than an
indirect source of trichloroethylene; see Appendix C for POTW data.
-------
CO
use
Table 3-3. Trichluroethylene Materials Balance: Use. 1978 (kky/yr)a
ConTained/Recycle
Input
Degreasiny1'
Cold Cleaning 30.000
0|ien-tup vapor 56.000
Conveyorized vapor 21.000
Fabric scouring 10.000
3S.OOO
66.000
25.000
12.000
9.000
6.000
1.700
2.700
Discontinued0
Coffee Decaffemation
Deer foam suppressant
Dry cleaning
Film cleaning
Paint additive
Grain drying
Refrigerant
Lumber drying
Anaesthesia
Cosmet ics
Oilfield wax removal
Rubber products
Fungicides . 3.800d
Adhesives \-
Cleaning fluids | 1.200d
Chain transfer agent 5,000
in polyvinyl chloride
product ion
Exports9 16.000
Air
15.000
51.000
21 .000
6.000
Releases
Land
Water
7.000
5.300
1.300
2.100
3.000
2.300
900
3.800*
l,200e
5.000*
16.000
-neg-
Numbers may not add due to rounding to two significant figures.
See Table 3-5 for derivation of degreasing figures; totals do not include ss2X TCE destroyed by Incineration. Numbers
in parenthesis are lota) solvent (virgin * recycle from previous use).
c) See text for explanation of discontinued uses.
d) Munster. 1900; Bernard. 1980.
e Assumed total input is released to the air.
fj Represents amount of trichloroethylene chemically incorporated into the polymer.
g U.S. Department of Commerce, 1980.
-------
approximately 380 kg of crichloroechylene were discharged to surface
vaters (Catalytic 1979). This value is calculated on the basis of raw
vasreload and,therefore, represents a maximum value. Possible mechanisms
for trichloroethylene removal from mixed liquor suspended solids in an
activated sludge system include biological degradation and mechanical
stripping as a result of aeration (Su and Garin 1972). Aerated lagoons
lower aquatic discharges at the expense of air emissions. This total
aqueous discharge was divided proportionally between the three plants
producing trichloroethylene. (See Table 3-1.) Specific data regarding
solid waste discharges are unavailable. Assuming that solid wastes are
largely incinerated or recycled as chlorinolysis process feedstocks
[the waste may be a suitable feedstock for tetrachloroethene/carbon
tetrachloride via a chlorinolysis process (EPA 1976)], land discharges
of trichloroethylene are presumed to be negligible.
3.3.3 Publiclv-Owned Treatment Work (POTWs)
Trichloroethylene loading to POTWs is largely dependent upon vari-
ations in a particular municipal area. A framework for calculating the
total trichloroethylene flow through the nation's POTWs is provided by
data from a recent EPA study (EPA 1980b). A materials balance of tri-
chloroethylene at the treatment plants can be constructed using a total
POTW flow of approximately 1011 I/day (EPA 1978b) and median values of
28 ug trichloroethylene/1 (influent) and 4 yg trichloroethylene/1 (ef-
fluent). (See Appendix C.) A trichloroethylene "slug" discharged to a
POTW would effectively settle to the bottora of a primary clarifier (Su
and Garin 1972). since TCE is relatively more dense than water. It is
assumed for purposes of these calculations that influent and effluent
flow rates are equal, i.e., that water loss from sludge removal and
evaporation are small compared to influent flows. The results of the
calculations show an input to POTWs of 1,020 kkg trichloroethylene and
an effluent of 150 kkg. (See Figure 3-1.)
Trichloroethylene discharged in sludge can be estimated from the
trichloroethylene concentration in sludge and quantity of dry sludge
produced annually, 6.0 x 106 kkg (EPA 1979f). Assuming the trichloro-
ethylene concentration of POTW wet sludge to be 30 ug/1 (see Appendix C)
and that wet sludge is 95 percent water by weight, approximately 4 kkg
of trichloroethylene are discharged as sludge. As ocean dumping of
sludge is mandated to cease by 1981 and assuming that more stringent
air quality standards curb incinerator use (EPA 1979g), the 4 kkg of
trichloroethylene contained in sludge are assumed discharged to land.
(See Figure 3-1.)
The trichloroethylene released to the atmosphere may be estimated by
the difference from the above calculations given the following assumptions:
(1) trichloroethylene recycled within the activated sludge process will
eventually be "wasted"; (2) the trichloroethylene biologically degraded
is negligible; and (3) trichloroethylene is lost to the atmosphere by
mechanical stripping, or aeration. Thus, an estimated 870 kkg of tri-
chloroethylene is released to the atmosphere from POTW's. (See Figure 3-1.)
3-9
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3.3.4 Transportation-Related Accidents Involving Trichloroethvlene
Transportation (loading and transfer) of trichloroethylene night
result in accidental spills or leakage of vapor and/or liquid. Tri-
chloroethylene is transported by rail (35.6 percent), truck (43.0 percent),
and barge (16.2 percent) (EPA 1980c). Appendix D is a list, maintained
by U.S. Department of Transportation's Material Transportation Bureau
(DOT 1980), of transportation incidents involving the release of tri-
chloroethylene to the environment from 1971 to the present. It is
interesting to note that the number and severity of the accidents are
low, with no deaths or injuries resulting. Further, there was a total
of only $551 in damages reported. For 1979, 675 liters, approximately
one kkg, were released to the atmosphere from such incidents. DOT now
requires special modifications, to tank cars shipping hazardous materials
in commerce, including head shield, shelf couplers, and thermal protec-
tion (49 CFR 179.105) to further reduce the frequency and severity of
future accidents.
3.3.5 Inadvertent Sources of Trichloroethylene Emissions
In general, any human activity that unintentionally disperses a
chemical to the environment is an "inadvertent source" of that chemcial.
Inadvertent sources are likely since chemical species do not react via
a single reaction pathway. Depending on the nature of the reactive
intermediate -there are a variety of pathways that lead to a series of
reaction products. Inadvertent sources of a chemical are not limited
to those of chemical manufacturing processes, however. Disinfection
of drinking water or wastewaters by chlorination, for example, is a po-
tentially. Important" inadvertent: source of chlorinated organic hydrocarbons.
This section will examine possible inadvertant sources of trichloro-
ethylene emissions grouped accordingly:
• Trichloroethylene emissions from production of other
chlorinated hydrocarbons; and
• Chlorination of drinking water.
Table 3-2 is a summary chart for inadvertent sources.
3.3.5.1 Production of Other Chlorinated Hydrocarbons
Quantifiable discharges of trichloroethylene have been documented
from the production of vinyl chloride monomer, and tetrachloroethene
manufacture. Both will be discussed briefly here and put in the context
of inadvertent sources of trichloroethylene releases, as illustrated
in Table 3-2.
There are two sources of trichloroethylene emissions during vinyl
chloride monomer (VCM) production: solid waste from the 1,2-dichloroethane
purification column and reactor VCM tars. Solid wastes, containing tars,
3-10
-------
FUGITIVE STORAGE
EMISSIONS EMISSIONS
\ |
1 1
HC1 TO OTHER PROCESSES | |
1 ' '
1 i i
CHLORINE
n nui fur* i\i/*ui mi i nc
ClIIYLLNt Ul CHLORIDE
NaOII _
CHLORINATED C9's
FROM OTHER £
onfirccccc
rKULtabta
TETRA-and
TRICHLOROETIIVLENE
PRODUCTION via
DIRECT CIILORINATION
1 1
fa f
NEUTRALIZATION TARS TO
AND DRV ING INCINERATION
UASTEWATER
EMISSIONS FROM
COLUMN VENTS
\
1
1
9
1
1 STORAGE
EMISSIONS
*
1
TRICIILOROETHENE 1
• -
1
TETRACHLOUOETHENEI 1
1
1
1
1
IIANIIL ING
EMISSIONS
*
1
.
L^ -J-_-to._l OADING
i -~ "
|
I
II
""
AIR EMISSIONS
WATER DISCHARGES
Figure 3-2. Environmental Releases from Trlchloroethylene and Tetrachloroethylene Production by Chlorination
-------
spent catalyst, and dessicants are usually treated to recover organic
compounds present, then_ are either disposed in a landfill or incinerated,
thereby recovering chlorine as hydrogen chloride (McPherson e_t_ al. 1979).
Process emissions are dependent upon plant specific operating pa-
rameters and configuration. Based on the process description of Lunde
(1965) however, approximately 29 kg of "heavy" chlorinated organic
material are generated per kkg of 1,2-dichloroethane produced. Based
on a 1,2-dichloroethane production of 5.1 x 106 kkg, 1.5 x 105 kkg of
"heavy" chlorinated organic material were generated from the balanced
process. [This 1,2-dichloroethane production figure is at variance
with data reported by the United States International Trade Commission
(USITC), who exclude production data for intermediate products. The
figure cited here is based upon end product production and reported
yields.] Of this waste, approximately 4 percent may be regarded as
nonrecyclable tars; the remainder is presumed to be recycled to carbon
tetrachloride/tetrachloroethylene production. The trichloroethylene
concentration of the recyclable stream is estimated to be 3.6 percent
by weight (Lunde 1965) while that of tars is estimated to be 0.2 percent
(EPA 1975a). Using these assumptions, approximately 5,200 kkg of
trichloroethene are recycled. Assuming nonrecoverable tars to be the
only source of trichloroethylene dispersion to the environment, and
that these tars are incinerated with 99.9 percent efficiency, 12 kg of
trichloroethylene are emitted from this source. If disposed as solid
waste, 12 kkg are dispersed to land. (See Table 3-2.)
Production of tetrachloroethylene by direct chlorination at the
Deer Park, Texas plant of Diamond Shamrock has provided an opportunity
to examine trichloroethylene emissions from a facility that has put
trichloroethylene production on standby (EPA 1979d, SRI 1979). Process
discharges from a tetrachloroethylene plant have been estimated as
0.11 kg trichloroethylene/kkg product from the neutralization and drying
vent and 0.056 kg/kkg from the distillation vent. Thus, from this
75 x 1Q3 kkg capacity plant, and a production level 63 percent of capacity
(USITC 1979), an estimated 8 kkg of trichloroethylene were emitted to the
atmosphere. (See Table 3-2.) Aqueous discharges are calculated as
0.13 kkg based on emission factors described in Section 3.3.2. The waste-
water production of 0.42 kkg 1^0/kkg product and average trichloroethylene
concentration of 6,580 ug/1 are assumed to be the same for both tetra-
and trichloroethylene production; the two compounds commonly occur as
coproducts in the same facility, and are subject to the same waste treat-
ment processes. In comparison, total trichloroethylene production dis-
charges are estimated as 280 kkg to the atmosphere and 380 kg to water.
(See Section 3.3.2; Table 3-1.)
3-12
-------
3.3.5.2 Chlorinacion of Drinking Water and Wastewater
The chlorinacion of drinking water and wastevater has come under
close scrutiny recently, largely due co the discovery that chlorina-
tion of residual organic matter in such waters may lead to the formation
of chlorinated degration products (Glaze and Henderson 1975, Rook 1977,
Dowty et. al. 1975). Trichloroethylene has been identified among thir-
teen halogenated hydrocarbons from New Orleans drinking water (Rook 1977).
The EPA National Organic Monitoring Survey identified trichloroethylene
at concentrations in the low ug/1 range in samples from 113 U.S. com-
munity water supplies (EPA 1977c). As shown in Appendix E, however, the
results of this broad sampling effort are ambiguous. That is, the source
of such chlorinated organic chemicals cannot be readily identified (e.g.,
whether they are in the raw water prior to treatment or introduced as a
result of chlorination). However, it is possible that chlorination of
these waters could be a source of trichloroethylene, as the number of
positive results is less in samples that have been quenched with a
chlorine reducing agent than those that have not (i.e., terminal). In
addition, trichloroethylene and other nonaromatic and aromatic compounds
have also been found at ug/1 levels in superchlorinated (2000-4000 ug/l)
wastewater samples (Glaze and Henderson 1975, Dowty et al. 1975). None-
theless, it is estimated for the purposes of this materials balance that
a negligible amount of trichloroethylene is discharged to the environ-
ment by this inadvertent source.
3.4 USES OF TRICHLOROETHYLENE
In the past, trichloroethylene was used in a variety of applications,
including medical anaesthesia, decaffeination of coffee, food and spice
processing, dry cleaning and leather processing. As shown in Table 3-3,
current uses of trichloroethylene have declined markedly.
Existing and anticipated regulations (reflecting concerns about
trichloroethylene toxicity), increased cost of raw materials, and the
availability of solvents with similar properties, such as tetrachloro-
ethylene, carbon tetrachloride and 1,1,1-trichloroethane, have curtailed
the trichloroethylene market. The remainder of this section consists
of a discussion of the present use patterns of trichloroethylene. Spe-
cifically, trichloroethylene consumption and losses in degreasing oper-
ations and minor applications are presented. A brief discussion of
discontinued miscellaneous uses is also included.
3.4.1 Present Use Patterns
In response to declining demand and improved solvent recovery,
production of trichloroethylene dropped sharply from 206,000 kkg in 1973
to 136,000 kkg in 1978, see Figure 3-4, (USITC 1979). Moreover, an
increasing proportion of U.S. trichloroethylene production, 11 percent
in 1978 as compared to 25 percent in 1979, has been exported (Dept. of
Commerce 1980).
3-13
-------
FUGITIVE
EMISSIONS
STORAGE
EMISSIONS
EMISSIONS FROM
PROCESS VENTS
ui
HYDROCHLORIC ACID
PROCESS HATER.
AMMONIA CATALYST.
OXVGtN.
CHLORINE OR HYDROGEN CHLORIDE,
ETIIYLENE DICIILORIDE,
C2 CHLORINATED ORGANICS
FROM OTHER PROCESSES
TETRA-and TRICIILOROETIIYLENE
PRODUCTION via
OXYCIILORINAT10N
*STORAGE
|EMISSIONS
ORGANIC RECYCLE
SYSTEM AND STORAGE
TARS TO INCINERATION
BY PRODUCTS
TRICHLOROETIIENE
TETRACHLOROETIIENE
AQUEOUS WASTE
AND CATALYST FINES
TO WASTE TREATMENT
STORAGE HANDLING »
EMISSIONS EMISSIONS
STORAGE
STORAGE
'LOADING
'LOADING
I AIR EMISSIONS
I
WATER DISCHARGES
Figure 3-3. Environmental Releases from Tetra- and Tricliloroethylene Production by Oxychlorlnatlon
-------
2.75
2.50
o>
ft
2 2.25
x
•o
O)
u
2
,2 1.75
1.50
1.25
n
r» OB OL
m in m
9 9> «
to r»
<0
-------
Of the remaining domestic supply of trichloroethylene, over 90 per-
cent has been consumed historically in degreasing operations (EFA 1979a).
Minor uses of trichloroethylene represent only 4 percent of the total
domestic consumption and include the production of fungicides, cleaning
fluids and adhesives (Munster 1980, Bernard 1980); a list of represen-
tative products are presented in Table 3-4. The remaining trichloro-
ethylene, or 4 percent of total production, is used as chain terminator
in polyvinyl chloride production (Munster 1980, Bernard 1980).
3.4.2 Degreasing Operations
Solvent degreasing is the removal of oils, fats, waxes and grease
from metal, plastic, glass and textiles by an organic solvent. This is
a basic step in both large and small industries, such as machinery pro-
duction prior to painting or electroplating, and small electronics work-
shops or auto service centers. (See Appendix F.)
Trichloroethylene is one of the most versatile solvents used for
degreasing operations. Because of its low boiling point (relative to
water), strong solvent properties, and, until recently, relatively low
cost, trichloroethylene has been employed in an estimated 160,000 oper-
ations annually (EPA 1979b). Between 1956 and 1977, the price of tri-
chloroethylene rose, with fluctuations, from S0.237/kg to 30.462/kg
(USITC 1977).
Solvent operations are classified as either metal cleaning (cold
cleaning, open-top vapor degreasing and conveyorized vapor degreasing)
or fabric scouring. A flow diagram of a degreasing operation is pre-
sented in Figure 3-5. Approximately one-third of the total environmental
releases from solvent degreasing occur as waste solvent (EFA 1977a).
Waste solvent is the liquid containing solvent and impurities removed
from degreased parts, and is distinct from vapor emissions (due to
evaporation from the degreaser) or from carryout of solvent on treated
parts. Estimates of waste solvent generation by degreasing operation
are presented in Table F-2 (Appendix F). Information on waste solvent
disposal practices is scant; however, approximately 45 percent of the
waste solvent is assumed reclaimed by distillation. Distillation of
solvent from oil-containing waste solvent is performed either by con-
tractors or in-house by large users. Most degreasers have external
stills, permitting uninterrupted operation. The bottoms from these
stills, which contain the metals, oils and other impurities removed
from the degreased parts, can be incinerated or landfilled. The latter
is the less costly and more dominant practice (EPA 1977a). Emissions
from each degreasing operation are discussed in the following sections
and are summarized in Table 3-5.
3-16
-------
Table 3-4. Selection of Commercial Products Containing Trichloroethylene
Adhes-Off
(Harvey Labs Inc.)
Trichloroethylene
Petroleum base
Balkamp Klean and
(Balkamp Inc.,
Corp.)
Trichloroethylene
Prime
Mfr. Loctite
Bowes Buffing Solution
(Bowes Corp.)
Xylol
Trichloroethylene
Carboff
(Hoicomb Corp.)
Cresol >10%
Methylene chloride >10%
Trichloroethylene 1-10%
Carbona Cleaning Fluid
(Carbona Products Co.)
Trichloroethylene 44%
Petroleum solvent 56%
Carbona No.10 Special Spot
Remover
(Carbona Products Co.)
Trichloroethylene 40%
1,1,1-Trichloroethane 10%
Petroleum Solvent 50%
Lacco Chlorosan
(Los Angeles Chemical Co.)
Orthodichlorobenzene 59.5%
Trichlorobenzene 6.3%
Trichloroethylene 6.4%
Pine Oil 4.4%
Glamorene Dry Cleaner for Rugs
(Glamorene Products Corp.)
Chlorinated hydrocarbon (TCE)
Petroleum distillate
Wood flour
Instant Chimney Sweep
(Miracle Adhesives Corp.)
Trichloroethylene 34%/wt.
Propel!ant freon 25%/wt.
Mole a Gopher Get
(Mole a Gopher Get Mfg,
Methylene Chloride
Naphthalene
Paradichlorobenzene
Trichloroethylene
Co.)
46.4 %
1.24%
1.24%
51.1 %
PMD-77
(Oixo Company, Inc.)
Diethyl diphenyl dichloroethane
and related compounds 10.5%
2,2'-Methylenebis
(4-Chlorophenol) 0.2%
Tetrachloroethylene 45.8%
Trichloroethylene 42.6%
Sirotta's Sircofume Liquid Fumiga-
ting Gas
(Sirotta, Bernard, Co., Inc.
Carbon tetrachloride 96.
Ethylene dichloride 1.
Tetrachloroethylene 1.
1,1,1-Trichloroethane 1.
Trichloroethylene
0%
0%
0%
0%
Lethalaire B-5
(Virginia Chem. Inc.)
Trichloroethylene
1.0%
31.0%
Source: EPA, 1979a
3-17
-------
COAl GAS
OR FbEl OIL
o —
OEGREASER
CONDENSER
TO WASH
WATER
TREATMENT
WATER
SEPARATOR
SOIVENT
RECOVERY
STiu.
r STEAM
SOLVEDT
STORAGE
INDUSTRIAL BOIUR
SOLVENT RECOVERY SYSTEM
•{J
TO AIR TO AIR
vV
SLUDGE TO WASTE
It.f. LANOflLU
'SEPARATOR
TO WASTE-
WATER
TREATMENT
TO SOLVENT
STORAGE
CARBON ADSORPTION SYSTEM
KNSES
Figure 3-5 Degreaser Flow Diagram
1} Part to be cleaned is conveyed manually or automatically into the
degreaser.
2) After degreasing, part manually or automatically withdrawn or sent
to next operation.
3) Solvent heated by gas, electricity or steam.
4) Diffusing solvent can be collected by exhaust hood and vented to
atmosphere or 6.
5) "Dragout" of solvent with the work.
6) Carbon adsorption system.
7) Solvent loss balanced by periodic addition of solvent from storage
tanks or drums.
8) Solvent contaminated with grease or oil (waste solvent) sent to
solvent recovery system.
9) Distillate is condensed, sent through water separator, and placed in
storage.
10) Boiler provides steam if required.
Source: EPA. 1979b.
3-18
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Table 3-5. Trichloroethylene Materials Balance: Dear-easing Operations. 1973 (kxg/yr)«
Opera:: en
Cold Cleaning
Open-Tac Vaoor
Conveyori zed Vapor
fabric Scouring
TOTALS
l
. Total
Use*
35.000
66.000
25,000
12.000
140.000
Virgin
Solvent6
30.000
56.000
21.000
10.000
120.000
Recycie-
9.000
6,800
1.700
2,700
20,000
incineration^
1.000
750
190
300
2.200
Total waste
Solvent Load*
20,000*^
15,000
3.800
6.000
45,000
environmental releases
Process
Emissions
15.000
(11.000-20.000)
51 000
(36.000-67.000)
21 000
(15.000-28,000)
6.000
(4.200-7,800)
93.000
Land" .a-.er--
7.000 3.000
S.300 2.300
1.300 570
£.100 900
16.000 S.8CC
a) All figures have been rounded to two significant figures.
D) Eased on apparent 1978 consumption figures for tnchloroethylene and distribution figures deriveo from -PA (lS79o!- to-ai
use • virgin solvent * recycle from previous use; see figure F-l (Appendix F) for calculations.
c) Assumes 45S of the waste solvent load is reclaimed through distillation and recycled (EPA, I977a).
d) Approximately 51 of waste solvent Is assumed to be disposed of oy incineration {EPA, iS77a) resulting in negheisle
air emissions*
e) There are two categories of solvent losses recognized: evaporative and waste solvent loading, waste solvent loacinc was
calculated according to release factors presented in Table F-2 (Appendix F).
f) Insufficient data precluded the calculation of an emission factor on a solvent-by-solvent basis - thus all solvents are
assumed to have the same emission factor calculated as follows: cold cleaning: 430 g/ke »301; open-top vapor: 775 o/kc
;30»; conveyor-lied vapor; 850 g/kg +301; and fabric scouring: 500 g/kg *30S (EPA, 1979a).~ The uncertainty range -as
"sea on calculations presented In IPA (I977a) and witn personal communications of the authors with J. i. Shumake- of
U.S. trA. (EPA, 1979a).
g) The range presented represents the *30* uncertainty factor on the calculated value.
h) Assumptions were made based on engineering judgements as follows: 351 of the total waste solvent load Is assumes to be
disposed of to land (i.e., dumped onto grounds surrounding the user facility or 1n landfills) and 15s to water (i.e.
dumped in drains). These totals are undoubtedly high, as most of the solvent should volatilize to the atmospnere. Onl»
20. of the metal finishing plants are direct dischargers. (Note: the remaining 4SS Is recycled after distillation and" 5*.
is assumed to be incinerated, see Footnotes e and d). (EPA. 1977a).
1) The waste solvent load from cold cleaners was calculated based on the factors for the maintenance ana manufacturing
ana'maintenance'lecilrles res^ectiv I™"' 7'7°° k"9 "* 12'25° "* °f "*"* "'*"* "*" 9eBeratea b* "»nufacturing
J) Approximately 33« of the waste solvent load from maintenance cold cleaners (i.e., automotive maintenance facilities) is
assumed to be disposed with waste crankcase oil. It Is further assumed that the crankcase oil is used for dust control
on unpavea road (EPA, i9//a).
3-19
-------
3.4.2.1 Cold Cleaning
There are two major applications for cold cleaners—maintenance
and manufacture. Maintenance cleaners are used primarily in automotive
and general plant cleaning, whereas the manufacture cleaners are inte-
gral to metal working production. Cold cleaning uses solvent in the
liquid state (at room temperature or sometimes heated below the boiling
point), and includes spraying, brushing, and soaking operations. Typi-
cally the solvent is agitated by a pump, compressed air, or by ultra-
sonics; in some cases, the parts to be treated are agitated within the
bath. The design of a cleaner varies with the types of parts to be
cleaned, required materials handling (i.e., manual and batch loaded
conveyorized systems), the agitation technique, the size of tank re-
quired, and the frequency of cleaning. As shown in Figure F-l (Ap-
pendix F), solvent is lost to the environment by: evaporation from
the bath, spray and agitation operations, carry-out on treated parts;
and waste solvent disposal (EPA 1977a).
Cold cleaning is the largest user of trichloroethylene in the degreasing
industry with the compound utilized in approximately 150.000 operations
annually (EPA 1979b). A geographic distribution of all cold cleaning
operations is presented in Figure 3-6. As shown in Table 3-5, cold
cleaning produced 45 percent (20,000 kkg) of the total waste solvent
trichloroethylene load from degreasing operations. Total trichloro-
ethylene releases from cold cleaning are estimated as follows:
15,000 kkg to air; 7,000 kkg to land; and 3,000 kkg to water. Approx-
imately 9,000 kkg of trichloroethylene are assumed to be recycled (see
Table 3-5; releases based on total solvent used, i.e., virgin solvent^
plus chat solvent recycled).
3.4.2.2 Open-Top Vapor Degreasing
In open-top vapor degreasing, a vapor layer is created over a
solvent bath by electric, steam or gas heat (Watson 1973). The metal
parts to be cleaned are then dipped into the vapor. As the vapors
condense on the metal, the impurities are washed off. In addition, a
spray may be used to rinse the part (Spring 1967). Although cooling
coils in the tank maintain a distinct boundary between the vapor layer
and the surrounding air. vapor does escape as a result of evaporation,
agitation of treated parts, and solvent carry-out on parts. (See
Figure F-2, Appendix F). In practice, exhaust hoods are often used
to vent escaping fumes to the air.
Open-top vapor degreasers are usually site-specific (i.e., located
at the site of the material to be cleaned), operated manually, and used
chiefly only during a small part of the work day. They are primarily
used in metal working plants or for maintenance cleaning of Intricately
designed electrical parts requiring a high degree of cleanliness
(EPA 1977a).
3-20
-------
> SC.DDC
Figure 3-6. Geographic Distribution of Cold Cleaning Operations (EPA, 1979b)
3-21
-------
Over 50 percent (or >11,000) of the estimated 21,000 degreasing
operations use trichloroethylene as the solvent of choice (EPA 1979b).
The geographic distribution of all open-top and conveyorized vapor de-
greasing operations is shown in Figure 3-7.
Emissions can be controlled with activated carbon systems, use of
tank covers during idle time, adequate freeboard height, proper sizing
of treated parts in relation to the tank, minimum agitation of the bath,
and use of additional condensers to prevent evaporation and adequate
freeboard height (Watson 1973, EPA 1979b). Freeboard is the distance
from the top of the vapor zone to the top of the degreaser tank. This
is usually established by the location of condenser coils, which pro-
tect the solvent vapor from outside air disturbance. For trichloro-
ethylene, the freeboard is usually 50-60 percent of the degreaser width
(EPA 1977a). In contrast to cold cleaners, most releases from open-top
vapor degreasers are not from the waste solvent load but rather from
vapor diffusing from the degreaser. Estimated total trichloroethylene
releases in 1978 from this degreasing operation were 51,000 kkg to the
atmosphere, 5,300 kkg to land, and 3,000 kkg to water; 6,800 kkg were
assumed to be recycled. (See Table 3-5; based on total quantity of
solvent used).
3.4.2.3 Conveyorized Vapor Degreasing
In this continuous version of the open-top method, manual handling
has been eliminated and the operation is typically located at a central
cleaning station within a plant requiring a steady flow of products
to be degreased. Conveyorized degreasers continuously redistill solvent
and return it to the bath; the conveyor speed can be controlled to
minimize agitation of the bath (EPA 1977a). Sources of releases from
conveyorized degreasers are depicted in Figure F-3 (Appendix F). Since
the degreasers are normally enclosed and the workload large, solvent
loss is greatest from carry-out with parts.
Trichloroethylene is used by 1,700 operations employing conveyor-
ized vapor degreasing (EPA 1979b). The total geographic distribution
of all vapor degreasing operations (i.e., open-top and conveyorized)
is presented in Figure 3-7. Total air emissions from this degreasing
operation in 1978 were calculated as 21,000 kkg. As shown in Table 3-5,
waste solvent trichloroethylene disposed of on land and in water amounted to
1,300 kkg and 570 kkg, respectively; 1,700 kkg were assumed to be recycled.
3.4.2.4 Fabric Scouring
Fabric scouring, the only nonmetal cleaning degreasing operation
discussed, is essentially a cold conveyorized degreaser. In this
operation, "grey" goods (raw or untreated fabrics) are cleaned with
solvent before finishing (dyeing and fabrication). There are three
types of solvent scouring processes for fabrics; textile scouring,
wool scouring, and multilayer treatment, in which textiles undergo
3-22
-------
NUM8EE Of OPERATIONS
0 to 100
100 to 500
500 to 1.000
> 1.000
Figure 3-7. Geographic Distribution of Vapor Degreasing Operations
Includes open-top and conveyorized degreasers.
Source:EFE, 1979b.
3-23
-------
solvent scouring in several layers to increase throughput (EPA 1979b).
The conveyorized fabric is sprayed, cooled and fed to the next finishing.
stage while the solvent and removed impurities are separated (EPA 1979b).
Emissions occur through entrances to the scouring machine and are ex-
hausted to the atmosphere (see Figure F-4, Appendix F). Although not
in wide use, an activated-carbon system can recover up to 98 percent
of the solvent from exhaust (Watson 1973).
Less than 700 (of the more than 9,000) fabric scouring operations
are estimated to use trichloroethylene. The geographic distribution
of all fabric scouring operations is shown in Figure 3-8. Total re-
leases of trichloroethylene from this process in 1978 were estimated
as 6,000 kkg to the air, 2,800 kkg to land, and 900 kkg to water.
Approximately 2,700 kkg of trichloroethylene were assumed to be recycled.
(See Tables F-2 and 3-5.)
3.4.3 Emissions from Minor Applications
Limited data are available concerning the miscellaneous minor uses
of trichloroethylene. From the literature, it is estimated that 5,000
kkg of trichloroethylene are consumed on an annual basis in the produc-
tion and use of fungicides, adhesives, and cleaning fluids. All of the
solvent is assumed to be dispersed to the atmosphere (Bernard 1980,
Munster 1980). Approximately 4 percent of trichloroethylene production
(5,000 kkg) is used as a chain terminator in polyvinyl chloride (PVC)
production (Bernard 1980, Munster 1980). Releases of trichloroethylene
to the environment from PVC production are negligible,as trichloroethy-
lene is introduced into the slurry in relatively small amounts and
becomes chemically incorporated into the polymer. (See Table 3-3.)
3.4.4 Discontinued Miscellaneous Uses
Many of the minor applications for which trichloroethylene was
once used or considered suitable are no longer practiced (ORNL 1976).
Where published information was unavailable or in conflict, contacts
were made with industry representatives to ascertain current tri-
chloroethylene use practices. Although cited in the literature as a
minor use (ORNL 1976, Joyce 1979), trichloroethylene is no longer used
by the dry cleaning industry because of its aggressive solvent action
on acetate dyes and textiles (Woolsey 1980). Because of its recognized
toxicity, trichloroethylene is no longer used as an anaesthetic (Hattox
1980, Yamaner 1980). In a similar manner, coffee companies that had
used trichloroethylene to decaffeinate coffee later abandoned its use
in anticipation of its prohibition by the Food and Drug Administration
(Gianetta 1980, Adinolfi 1980). Furthermore, trichloroethylene is
regarded as too expensive for use in grain drying (Frederick 1980) or
wood treatment (American Wood Preservers Association 1980) and unsuitable
as a refrigerant (Evans 1980). An obscure application, wax removal
from oil field pipelines, (ORNL 1976) is no longer practiced, as it
3-24
-------
MJM3ER 0' OPERATIONS
Oto 50
50 to 500
500 ts l.ODO
> 1.000
Figure 3-8. Geographic Distribution of Fabric Scouring
Operations (EPA, 1979b)
3-25
-------
results in unwanted carry-over of trichloroethylene into oil refineries
(Smyth 1980, Grundman 1980). While research on the use of trichloro-
ethylene as a solvent for surface coatings of paint has been reported
in the literature, commercial development appears to have been unsuc-
cessful (Leonard 1969).
3.5 MISMANAGEMENT 0? TRICHLOROETHYLENE
Historically, contamination of ground water supplies has been tied
to disposal practices. In terms of trichloroethylene, pollution of
ground water and drinking water supplies appears largely attributable
to migration and leaching of the chemical (either uncontained or stored
in corroding 55~gallon drums) from unlined or improperly lined landfills
(municipal and industrial), settling ponds, old dredge pits, open fields,
and old industrial sludge pits. In addition, direct discharge of tri-
chloroethylene into leaking sewer lines or from leaking storage tanks
and faulty septic lines has been recorded (Massachusetts 1979, Fishburn
1980). Not surprisingly, EPA has documented several hundred cases of
damage to human health and the environment resulting from improper man-
agement of hazardous waste. Those incidents specifically related to
trichloroethylene use and disposal are listed in Appendix G. In many
cases, the specific source or generator of the trichloroethylene-
containing wastes is unknown or not easily identified. Nevertheless,
a review of these damage incidents reveals present or imminent ground
water contamination, resulting in partial or complete loss of private
residential, industrial and/or municipal wells as drinking water sources.
3.5.1 Selected Damage Incidents
Reported damage incidents are not a recent development in the
history of trichloroethylene use. Two cases of well contamination
were described in 1949. In the first, trichloroethylene escaped from
a burst tank during a factory fire, saturated the ground and contam-
inated a well located near the factory. As the well was situated in
gravel only 20 ft from a river, the authors were surprised that
trichloroethylene odors remained at the well after 4 years, stating
that "one might have expected that the movement of water through the
gravel would have removed the contaminant." In the second case, a
trichloroethylene plume seeped through gravel from an open field dump
site 150-200 yards to a well, registering 18,000 ug/1 trichloroethy-
lene, and causing stomach disorders and giddiness in consumers of the
water. The authors' conclusions: "...contamination by compounds of
this nature is likely to be very persistent, and there is some evidence
of toxicity at very low concentrations." (Lyne and McLachlan 1949)
Recent analytical studies have revealed several cases of trichloro-
ethylene contamination. In New Jersey, testing of eight public water
supplies (rural, suburban and urban) showed levels of 170-400 ug/i
trichloroethylene (Kasabach 1980). Xear the Aerojet General rocker
plant and its subsidiary Cordova Chemical Company (located east of
3-26
-------
Sacramento, Calfornia), levels of 8,000 ^g/1 trichloroethylene have
been found in ground water (Phillippe 1980). Extensive contamination
of drinking water has been detected at various U.S. Air Force bases,
prompting an Air Force-wide testing of the wells (Fishburn 1980).
Presently the investigation is being conducted at Pease Air Force Base
in New Hampshire, Wurtsmith Air Force Base in Michigan, Mather Air Force
Base in California, and McClellan Air Force Base in California. Testing
is in the preliminary stages, and information is incomplete. Thus far,
however, levels of 6,700 ug/1 trichloroethylene in a production well
and 790 ug/1 in a test well have been registered on-base at Wurtsmith
Air Force Base (Grimes 1980), presumably the consequence of seepage
from a corroded underground 500~gallon trichloroethylene storage tank.
At McClellan, a base water supply well was similarly contaminated;
recent analysis revealed trichloroethylene levels of 700 ug/1. Else-
where on the McClellan property, an industrial waste sludge disposal
pit is the suspected source of 48 ug/1 trichloroethylene levels in an
off-base private well. Although a centrifuge is normally used to dry
the waste, with the dry sludge going to landfill, if the centrifuge
fails, the solvent-containing wet sludge is deposited in the unlined
disposal pits. A third potential on-base source of groundwater con-
tamination is degreasing shops that dump small (3:100 liters) quan-
tities of solvent directly into ditches behind the facilities
(Phillippe 1980).
In the cases where a particular point source can be isolated,
metal degreasing operations have been the primary contributors of
trichloroethylene wastes. The industries involved include machine
shops, electronics companies (Massachusetts 1979) and refrigerator
manufacturers (Joyce 1980), in addition to the aforementioned cases.
The Air Force used, and still uses, trichloroethylene (although in a
limited capacity) primarily in the jet engine and aircraft shops for
degreasing of parts. Aerojet General Rocket plant used trichloro-
ethylene for degreasing during production of solid rocket propellant
batch mixtures or to flush liquid propellant delivery pipes at test
areas. Cordova Chemical Company, the Aerojet subsidiary sharing the
common property, manufactured a variety of chemical products, including
herbicides, Pharmaceuticals and paint intermediates, and presumably
used trichloroethylene as a process solvent, as well as for degreasing.
3.5.2 Cumulative Environmental Releases
To assess and understand the impact of trichloroethylene in terms
of demonstrated and potential ground water degradation, estimates of the
cumulative amounts of trichloroethylene released to air, water, and
most importantly land over the period 1954-1978 are required. In the
simplest case, ground water contamination results directly from improper
disposal of trichloroethylene wastes; indeed, the many damage incidents
involving trichloroethylene are suggested to have arisen in this way.
3-27
-------
In this section, a summary table (see Table 3-6) has been developed
to estimate cumulative releases of trichloroethylene to land and water
for the period covering 1954-1973. To necessarily simplify the scenario,
only releases from degreasing operations have been considered. Apparent
consumption of trichloroethylene for degreasing operations has been as-
sumed to be constant over the whole period at 90 percent of total U.S.
production. Furthermore, for lack of better information, the distri-
bution of trichloroethylene consumption among the different types of
degreasing operations—*cold cleaning, open-top vapor, conveyorized vapor,
and fabric scouring—has been assumed to be constant. (See Tables 3-3 or 3-5.
Estimates of waste solvent loading, critical to any cumulative
calculations of trichloroethylene dispersion to land and water, were
based on release factors presented in Table F-2. From these estimates
of total waste solvent loading, it is assumed that only 10 percent of the
total waste solvent generated during the period of 1954 to 1972 was re-
covered (i.e., distillation), and that recovery practices increased (in
a linear fashion) during the period between 1972 to 1978 to an estimated
recovery/recycle level of 45 percent (EPA 1977a, see Table 3-6, Footnote G).
In addition, it was assumed that throughout this period, approximately
5 percent of the total waste solvent load was destroyed by incineration
(EPA 1977a), resulting in negligible air emissions. As shown in Figure 3-9,
it is assumed, based on communications with users (Stranges 1980, Thorpe
1980) and EPA estimates (EPA 1977a), that the remaining waste solvent
load is disposed of as follows: 70 percent on land and 30 percent to
water. In a worst case scenario (in terms of ground water contamination),
air emissions from open storage of waste solvent are considered insignif-
icant (see EPA 1977a). From these calculations, an estimated 730,000 kkg
of waste solvent trichloroethylene were dumped on land and 320,000 kkg
discharged to water (i.e., dumped in drains) during the study period.
3-28
-------
Table 3-6.
Cumulative Releases of Trlchloroethylene from Degreaslng Operations, 1954 - 1978 (10 kkg)a
Year
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
TOTALS
Production
138
145
158
150
138
165
160
145
160
165
170
190
220
225
230
275
281
225
200
206
176
132
143
135
136
4,500
Apparent U.S.
Consumption
Degrees 1ngc
124
131
142
135
124
149
144
131
144
149
153
171
198
203
207
248
253
203
180
185
158
119
129
122.
122i
4,000
Process
Evaporative
Emissions
84
89
97
92
84
101
98
89
98
101
104
116
135
138
141
169
172
138
122
126
107
81
88
83
83i
Waste
Waste
Solvent6
40
42
45
43
40
48
46
42
46
48
49
55
63
65
66
79
81
65
58
59
51
38
41
39
39i
1,300
Waste Solvent Disposition
Incineration
2.0
2.1
2.3
2.2
2.0
2.4
2.3
2.1
2.3
2.4
2.5
2.8
-3.2
3.3
3.3
4.0
4.1
3.3
2.9
3.0
2.6
1.9
2.1
2.0
2.0
Recycle
.0
.2
.5
.3
.0
4.8
4.6
4.2
4.6
4.8
4.9
5.5
6.3
6.5
6.6
7.9
8.1
6.5
5.8
8.9
10.0
9.9
13.0
15.0
18.0
Land
Disposal
24
25
27
26
24
29
27
25
27
29
29
33
38
39
39
47
48
38
35
33
27
18
18
15
13
730
Discharge
10
11
11
11
10
12
12
11
12
12
13
14
16
17
17
20
21
16
15
14
12
8
8
7
6
320
FOONOTES next page
-------
TABLE 3-6 (concluded)
a) Final totals do not add due to rounding.
b) Lowenheim and Moran, 1975; USITC; 1975-1979.
c) Apparent use of trichloroethylene for degreasihg operations is reported in the literature as 90-99% of
the total U.S. consumption of trichloroethylene (EPA, 1979a; EPA, 1979b). From these figures, the
assumption was made that 90% of total U.S. production from 1954 to 1978 was consumed by degreasing
operations.
d) Evaporative process emissions are calculated by determining the difference between the total amount of
solvent utilized in the specific type of operations and the waste solvent load (EPA, 1979b).
e) Waste solvent load was derived from release factors presented in Table F-2 and a total degreasing
trichloroethylene consumption of 120,000 kkg for 1978, resulting in a 32% value.
f) Approximately 5% of waste solvent is assumed to be disposed by incineration (EPA, 1977a) resulting in
negligible air emissions.
g) It is assumed that only 10% of the total waste solvent generated was recovered from the period of 1954
to 1972, and that recovery practices increased (in a linear fashion) during the period of 1972 to 1978
to an estimated recovery/recycle level of 45% (EPA, 1977a). These assumptions were based on: personal
communications with industry representatives (Stranges, 1980; Thorpe, 1980); the fact that the price of
trichloroethylene more than doubled during the period of 1972 to 1978 (USITC, 1972-1979); and the
promulgation of EPA regulations controlling solvent use and disposal.
h) The remaining waste solvent load is assumed, from communications with (Stranges, 1980; Thorpe, 1980)
and EPA 1977a) to be disposed of as follows: 70% is disposed on land (i.e., dumped at a landfill site,
on land at the user facility or mixed with crankcase oil and sprayed on land) and 30% to water (i.e.,
dumped in drains). In a worst case scenario (in terms of groundwater contamination), air emissions
from open storage of waste solvent are considered insignificant (see EPA, 1977a).
i) These figures differ from those presented in Tables 3-3, F-2 and 3-5 as exports and imports have not
been adjusted for. Rather 90% of the total production for each year was calculated for the degreasing
consumption figure.
-------
Total Solvent
Consumed In Oegreasing
68%
Process A1r
Emissions
32% Waste Solvent
17
Recycled
Incineration
3-14S
Dispersed to the
Environment
16-27S
Figure 3-9.
r
Water
30%
Disposition of Trlchloroethylene Consumed 1n Solvent
Degreaslng for the Period 1954 - 1978
Land
7W
It is assumed that only 10" of the total waste solvent generated was recovered from the period of 1954 to 1972,
and that recovery practices increased (in a linear fashion) during the period of 1972 to 1978 to an estimated
recovery/recycle level of 45S (EPA, 1977a). These assumptions were based on: personal communications witn
industry representatives (Stranges, 1980; Thorpe, 1980); the fact that the price of trichloroethene more than
doubled during the period of 1972 to 1978 (USITC, 1972-1979); and the promulgation of EPA regulations
controlling solvent use and disposal.
Approximately 5X of waste solvent is assumed to be disposed of by Incineration (EPA, 1977a), resulting in
negligible air emissions.
Percentage dispersed to the environment Is dependent on recycle practices.
3-31
-------
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3-3S
-------
4.0 DISTRIBUTION IN THE ENVIRONMENT
4.1 INTRODUCTION
Monitoring data are presented first in this chapter (Section 4.2).
Available literature has been scanned to determine trichloroethylene
concentration detected in various environmental media - air, water
(including groundwater),soil, and biota. The second part of this chapter
(Section 4.3) addresses the environmental fate of trichloroethylene.
4.2 TRICHLOROETHYLENE DETECTED IN THE ENVIRONMENT AND IN OTHER MEDIA
The U.S. EPA STORET files were searched for data concerning con-
centrations of TCE in ambient water and effluents. In six wells reported,
TCE was found at 0.14 ug/1 to 10 ug/1. Concentrations of 0.14 -g/1
to 300 ug/1 at about 180 ambient surface water monitoring stations were
reported, but most had concentrations of 10 ug/1 or less. At 17 stations,
no TCE was found in the analysis. In 270 reports of concentrations in
effluents, TCE was reported at concentrations of 0.01 to 1600 ug/l
although all but a very few were less than about 10 ug/1. Comparatively
few reports of TCE in sediments showed 0.07 to 580 ug/I;g. Table 4-1
summarizes STORET ambient water data by region.
Table 4-2 summarizes typical TCE concentrations in different media.
These readings are not specific to the U.S. In all media reported,
typical TCE levels are 10"^ to 10~^ °n a weight per weight basis.
Most fall in the 10~9 to 10 w/w range.
Table 4-3 shows concentrations of TCE detected in human tissue.
Most concentrations found in body fat, kidneys, livers, and brains were
in the 1-10-yg TCE/kg wet tissue range. These measurements were taken
in the U.K.
Table 4-4 shows TCE detected in foods from the UK. Concentrations
in foods ranged from not detected to 60 ug/kg, with most less than
10 pg/kg. No US data were found.
Many reports of TCE concentrations found in air are available,
both for the US and worldwide. These are given in Table 4-5. Back-
ground levels in areas away from centers of use (i.e. cities, etc.)
over land range from <27 ng/m3 to 4300 ng/m . On the basis of these
measurements an estimate of the pervasive background level in air is
32-53 ng/m . Concentrations over the open ocean range from
1 ng/m - 20 ng/m .
TCE has been found in wastewater, surface water, the ocean, drinking
water, and groundwater. A summary of information found concerning
these TCE levels is given in Table 4-6. TCE in wastewater was
found at concentrations <10 ug/l to 8000 '-g/l- TCE in surface water
(rivers and lakes) was found up to 200 -g/1, out most levels were nearer
4-1
-------
TABLE 4-1 TRICHLOROETHYLENE IN AMBIENT WATERS
Trichloroethylene (ug/1)
River Basin/Region
Northeast
North Atlantic
Southeast
Tennessee River
Ohio River
Lake Erie
Upper Mississippi
Lake Michigan
Missouri .River
Lower Mississippi
Colorado River
Western Gulf
Pacific Northwest
California
Great Basin
Unlabeled
UNITED STATES
Source: Combination of Remarked and Unremarked Data from U.S. EPA
STORET Water Quality Information Systems, as of October 2, 1980.
Observations
20
31
110
14
57
3
19
94
26
9
3
18
78
4
1
1
488
%
<10
IOC
97
96
93
98
67
74
87
85
99
100
100
99
100
100
100
94
Observations
10.1-100
3
4
2
21
13
15
1
1
6
in ranae
100.1-1000
7
33
5
4-2
-------
Table 4-2 WEIGHT/WEIGHT COMPARISON' OF TYPICAL Tf.ICHLOROETHENE
CONCENTRATIONS IS DIFFERENT MEDIA
DIFFERENT MEDIA
Comparison o£ Typical TCE Concentrations
Medium
Air
Rainwater
Surface Water
Potable Water
Sea Water
Marine Sediments
Marine Invertebrates
Fish
Waterbirds
Marine Mammals
Fatty Foods
Non-Fatty Foods
Human Organs
Human Body Fat
Minimum
(weight/weight)
Maximum
10
10
10
10
10
10
10
10
10
10
10
10
10
10
-9
-11
-11
-11
-10
-10
-9
-9
-9
-9
-9
-9
-9
Source: McConneUet al. (1975)
10
10
10
10
10
10
10
10
10
10
10
10
-8
-9
-9
-9
-9
-9
-8
-8
-7
i
-8
i
-8
-9
-9
-8
Concentrations have been expressed on a weight per weight basis in
order to facilitate comparisons among different media. These values
are not specific to the U.S.
i-3
-------
TABLE 4-3 TRICHLOROETHYLENE CONCENTRATIONS IN HUMAN
TISSUE3
Sample
Tissue
TCE Concentration
(wet tissue)
ug/kg
76
76
82
48
65
75
66
74
F Body Fat
Kidney
Liver
Brain
F Body Fat
Kidney
Liver
Brain
F .Body Fat
Liver
M Body Fat
Liver
M Body Fat
Liver
M Body Fat
Liver
M Body Fat
F Body Fat
32
<1
5
1
2
3
2
<1
1.4
3.2
6.4
3.5
3.4
5.2
14.1
5.8
4.6
4.9
Source: McConnell et al. (1975)
apparently from the UK.
4-4
-------
TABLE 4-4 TRICHLOROETHYLENE DETECTED IN FOOD FROM THE UK
Food Item TCE Concentration (_g/kg)
Dairy
Fresh Milk 0.3
Cheshire Cheese 3
English Butter 10
Hens Eggs 0.6
Meat
English Beef Steak 16
English Beef Fat 12
Pig Liver 22
Oils and
Margarine 6
Olive Oil (Spanish) 9
Cod Liver Oil 19
Vegetable Cooking Oil 7
Castor Oil " ND1
Beverages
Canned Fruit Drink 5
Light Ale 0.7
Canned Orange Juice ND
Instant Coffee 4
Tea (Packet) 60
Wine (Yugoslav) 0.02
4-5
-------
TABLE 4-4 TRICHLOROETHYLENE DETECTED IN FOOD FROM THE
UK (Continued)
Food Item TCE Concentration (_g/kg)
Fruit and Vegetables
Potatoes (S. Wales) ND
Potatoes (N.W. England) 3
Apples 5
Pears 4
Tomatoes (grown in reclaimed
lagoon at a chemical
plant) 1>7
Imported Black Grapes 2.9
Fresh Bread 7
aND - Not Detected
Source: 'McConnellet al. (1975)
4-6
-------
TABLE 4-5 SELECTED MEASUREMENTS OF TRICIILOROETim.ENE CONCENTRATinNS IN AIR
I.OCATIOH
Eii.st Coast Urban Areas
West Coast Urban Area
Vicinities of TCE
Manufacturing Sites
Vicinity of TCE User
Industrialized Areas
Ifl.-ilwurklng Shop In
Swudi-n
DATE
1974
4/74 - 1/76
11-12-76
1/77
pre 1979
prc 1963
CONCENTRATION
mln max mean
Ug/B3
<0.3 47 1-5 •
<3 - 34 ug/m3
<5 - 1440 ug/B3
-------
TABLE 4-5 SELECTED MEASUREMENTS OF TRICIILOROETIIYLENE CONCENTRATIONS IN AIR (Continued)
LOCATIOH
emote Areas - US
en Stations
Europe, Africa
01
PATE
1975 - 1917
7-8/1972
10/73
1972. 1974
CONCENTRATION
Range 0-3 i>g/o
Range 0-22 ng/o
Mean 6 ng/n
<65 ng/oj
<100 ng/ni
COMMENT
Moat In 0 - 100 ng/o range
Pacific N.W.
Talladega National Forest
California-Point Reyes.
S.F. Bay
Pullman. Wash.
Along a line from Lands End to
Cap Blanc (Spanish Sahara)
North Atlantic
REFERENCE
Cronn et al.
(1977)
Itolzer et al.
(1977)
Singh et al.
(1977)
Grlnarud and
Rasoiissen(197l
Murray and
Hlley(1971)
Su and Cold-
berg (1976)
Hurray and
Rlley 1973
COB et al.
(1976)
-------
TABU 4-6 COMPILATION OF MEASUREMENTS OP TRICHMMU>BTIIY,.ENE CONCENTRATIONS. IN WATER
LOCATION
Surface Water - U.S.
Vicinities of TCE
Manufacturing Plants
far 1 no-
I.E. Atlantic
Surface Water
'Mat Pacific
Pacific Coast - US
Iroundwater -
Raw
Finished
iroundwater - 8 states
N.J. Groundwater
N.Y. Public Water Systc
Nassau Co., N.Y.
Community
Water Supply Wells
Massachusetts
PATE
1977
11-12/1976
pre 1973
1-7/75
a
4/28/78
COHCEMTRATIOH
Range 0 - 5227 |ig/l
Mean 0 - 100 pg/l
0.1 - 5227 |ig/l
0-10 ng/1
0-15 ng/l
Mean Median Range ug/j
29.72 1.3 0.2-125
6.76 0.31 0.21-53
35000 lig/lmax
<1.0 |ig/l 1-1O 10-100 >IOO
"7 41 15 4
Max 19 ng/1
Max 300 ng/i
0 - 1000 yg/i
COMMENT
Four manfacturlng plants
- Dow Chemical. Freeport. TX
- PPG Industries. Lake Charlc
LA
- Ethyl Corp.. Baton Houge. LA
- Hooker Chemical. Taft. LA
13 38.5
25 36
28Z of 2894 wells were positive
73Z of 397 wells positive
18 of 39 positive
SO of 372 positive
13 communities
REFERENCE
Research Tri-
angle Insltute
(1979)
Battelle
Coluabua Lobs
(1977)
Hurray and
Rlley(1973)
Su and Cold-
berg (1976)
Conlgllo et al
(1980)
Special
.eglslatlve
tomnisslon on
Water Supply
(1979)
-------
TABLE 4-6 COMPILATION OF MEASUREMENTS OF TR ICIIU>ROETIIYLENE CONCENTRATIONS IN HATER
(Continued)
LOCATION
Other Surface/Drinking
Water
Finished Water
Samples - US
lew Jersey Drinking
later
lefferson Parish LA
lefferson Parish Tap
later
DATE
May - July 1976
CONCENTRATION
mean of positives 2.1 pg/1
nean of all 0.5 pg/1
<0.05 pg/1 median
1
2/7/77-8/5/77
iurface Water \
Raw
Finished
Inter Supply Systems
Her v Ing >75. 000
population
Unrcr Supply Systems
serving <75,000
population
Wnatvwatcr -
Semiconductor Raw Waste
Water
•
757 - 18017 ng/1
Mean Low High
0.2 Ug/1 0.1 Pg/1 1.4 ug/1
0.087 pg/1 0.2 pg/| 0.5 pg/1
0.19 pg/i mean
1.6 Pg/1 high
Mean Median Range pg/1
0.9 0.25 0.1-42
0.47 0.26 0.06-3.2
0.66 pg/1
avg.
0.32 pg/1
mln max mean
0.0066 3.5 0.25 pg/1
COMMENTS
5 ng/1 minimum quantifiable
limit
-28/113 positives In puMIc
water supplies In NOUS Phase 11
22/22 Samples
Mississippi River Water
Water entering distribution
system
found In 92/145 samples
ffcltles sampled Z positive
105 11.4
133 32.3
28/87 positive
Phase 1. 11. Ill of NOUS
9/26 positive
37/113 systems showed posltlv
7/87 nystems serving >75.000
have >0.5 pg/1
Fluw,pioport loncd average
concentration 0.19 l'8/l*
Flow rate 291.5 x 10° I/day
REFERENCE
Brass et al .
(1977)'
Research Tri-
angle lust 1 tut
(1979)
1
Conlgllo et al
( 1980)"
'enJeyfjraf t
ef_ al. (1979)
•
USEPA (I980a)
-------
TABLE 4-6 COMPILATION OP MEASUREMENTS OF TR1CIIUOROKTIIYLENB CONCENTRATION IN WATER
(Continued)
LOCATION
Sewage Treatment Plant
Effluents
Finished Water
Ambient
Rain
La Jolla, Calif.
Runcorn, U.K.
Snow
So. California
Central California
Alaaka
Ice
Reservoir
Lake
Untreated Water
I
PATE
CONCENTRATION
max 10 ug/1
•ax S Ug/1 •
max 188/ ng/l
S + 2.6 (ng/l)
ISO
39
30
20
38 - 65
S.I + 4.6
8/18 samples
72/182 samples
from a commercial machine
REFERENCES
EPA(1977b)
Su and Cold-
berg(1976)
-------
10 "jg/l or less. This generally agrees with the STORET data shown in
Table 4-1. In Che vicinities of plants manufacturing TCE, concentrations
as high as 5227 yg/1 were found.
Drinking water was sampled in the National Organics Monitoring
Survey. Where TCE was found in finished drinking water, concentrations
were generally less than a few -g,'l, with mean concentrations, if
detected, less than 1 ug/1 (see Table 4-6). With well water (ground-
water) the situation is different. TCE has been found at concentrations
of several hundred rnicrograms per liter and some have been in the high
milligram per liter range. In finished groundwater used for drinking,
concentrations up to 125 ug/l have been found. TCE was found in 28%
of 2894 wells tested in eight states.
Soil samples were taken in the vicinities of TCE manufacturing and
user sites (Battelle Columbus Labs 1977). Concentrations ranging fror.
none detected to 5.6 ug/kg (dry weight) were found. Few other soil
concentrations have been reported. Sediment samples at the same sites
showed up to 300 ug/kg (dry weight) TCE.
Pearson and McConnell (1975) and Dickson and Riley (1976) report
TCE concentrations found in marine fishes, birds, mammals, and algae in
the UK. While these data are not specific to the U.S., they do indicate
TCE levels that may be achieved. In marine fishes concentrations ranged
from <0.1 ug/kg to 480 ug/kg. In marine birds and mammals TCE levels
were between 2 ug/kg and 30 ug/kg. Marine invertebrates had levels
ranging from not detected to 250 ug/kg. Marine algae showed up to 22 '-g/kg.
When expressed on a wet weight basis, the concentrations fall in the lover
part of the concentration ranges reported and when expressed on a dry
weight basis, the concentrations are in the upper part of the range.
4.3 ENVIRONMENTAL FATE
This section reviews the major environmental pathways and fate of
trichloroethylene, as summarized in Figure 4-1. Atmospheric fate is
discussed first, followed by discussions of fate in water and in soil.
Following discussions of environmental fate processes, information
is presented concerning fate of TCE in solid waste materials and sewaae
treatment plants.
4.3.1 Atmospheric Fate
Trichloroethylene is not photolyzed in the atmosphere, but rather
is photooxidized. TCE does not absorb light in the visible or near UV
spectra of sunlight (Jaffe and Orchin 1962). Dahlberg (1969) determined
the absorption spectra of TCE; as shown in Figure 4-2 the absorption
spectra lie below the atmospheric cutoff limit of 290 nm.
Trichloroethylene forms many decomposition products when photo-
oxidized in the atmosphere. The half-life for this process in nature
has been estimated to be from a few hours to a few days. Decomposition
4-12
-------
I
M
U)
IrampiMt hom
Dislanl Souicct
(I>.U kl|l(lllll>l I OMI l-llll dll.lll
TiO|H»|iliefe - Photochemical Dcgiailaliun
(i./, -- Ktlay - 2 .lays!
Septic Sysleiiu
Percolate lo
Aquiler
Leaching lo Deep Soils
toumlwuler
DetfH|ilimi
Mitun
A<(iiilei (long residence lime)
FIGURE 4-1 MAJOR PATHWAYS OF TRICHLOROETHYLENE IN THE ENVIRONMENT
-------
10
togk
2000
2200
Wavelength (A)
2400
2600
Note: If the unit for the partial pressure of the absorbing molecule
is at M, the absorption coefficient is defined by
Where T = Temperature, K
p = Partial Pressure of TCE
5 = Path Length of Light
!„ • Initial Intensity of Light
Measured Intensity of Light
I
Source: Dahlberg 1969.
FIGURE 4-2 ABSORPTION SPECTRA OF TRICHLOROETHYLENE
4-14
-------
products include any or all of the following: phosgene, dichloroacetyl
chloride, trichloroacetyl chloride, formyl chloride, hydrogen chloride,
chlorine, carbon monoxide, chloral, ozone, formic acid, and nitric acid.
These products further decompose at various rates.
Although no information was found concerning the propensity of
TCE to sorb onto particulate, this is not expected to occur to a
significant extent due to TCE's high vapor pressure.
4.3.2 Fate in Water
4.3.2.1 Volatilization
Several experimenters (Jensen and Rosenberg 1975, Dilling et al.
1975, Neely 1976, Billing 1977) have determined in the laboratory the
evaporation rate of trichloroethylene from water. (See Table 4-7)
For most cases, a half-life of about 20 or 30 minutes was reported for
studies in which evaporation from a stirred beaker was measured. The
exception is the work of Jensen and Rosenberg (1975))in which TCE
apparently evaporated from a partially covered aquarium containing
seawater. The half-life in this case appeared to be 3-4 days.
Though these rates are indicative of the rapid volatilization of
TCE from water, they are not directly applicable to environmental
situations. Methods have been developed (Southworth 1979, Neely 1976,
Liss and Slater 1974) whereby volatilization rates from water bodies
can be estimated. (See Appendix G for a discussion of these methods.)
For representative environmental conditions (wind speed 3m/sec,
current speed 1m/sec), the half-life in a 1-m deep stream is estimated
to be about 3.5 hours. For lower wind speeds and stream depths up to
10 m, the estimated half-lives increase to about 11 days. These rates,
on the order of hours or days, are indicative of TCE's propensity to
volatilize rapidly from water bodies.
In a 1-m deep river flowing at 3.6 km/hr (1 m/sec) with a wind of
'3 m/sec, 90% of the TCE is estimated to volatilize in about 11.7 hours,
or 42 km downstream from the source. For the 10-m deep river, this time
increases to 37 days, which would correspond to 3200 km downstream at
a 1 m/sec flow rate. These estimates assume initially well-mixed
conditions and constant environmental conditions. (The results of the
EXAMS analysis discussed in Section 4.4.3 relate to this discussion.)
4.3.2.2 Hydrolysis
Trichloroethylene is reported to resist hydrolysis at 100°C, but
oxygen accelerates the decomposition rate (Dilling et al. 1975). Pro-
ducts from dilute solution hydrolysis or oxidation have not been reported,
but dichloroacetic acid and hydrogen chloride are likely products. In
4-15
-------
TABLE 4-7 MEASURED EVAPORATION RATES FOR TRICHLOROETEYLEXE
Experiment Measured Half-life Experimenter
250 n beaker 22 min Neely (1976)
200 m solution, 6.5 cm deep
Gently stirred
c0 = 1 mg/
250 m beaker
200 m solution, 6.5 cm deep 19 min Pilling et al.
200 rpm stirrer (1975)
c0 • 1 mg/
No stirring >^90 min
250 m beaker
200 o solution, 6.5 cm deep 16.9-24.5 min Dilling (1977)
200 rpm stirrer
c0 ° 1
4-16
-------
sealed tubes kept in the dark, the half-life of TCE was about 10.7
months at 25°C (Dilling et. al.. 1975). The reaction may have been
oxidation.
TCE is, therefore, not expected to hydrolyze at an appreciable
rate under environmental conditions, although hydrolysis may be significant
in groundwater, where other fate mechanisms are not operative.
4.3.2.3 Photolysis
TCE-water solutions were sealed in tubes and placed in sunlight
(Dilling et. al. 1975). TCE loss was noted. Most of the activity "was
probably due to oxidation and was probably free radical in character."
Half-life in this experiment was about 6-8 months. This observation is
in agreement with predictions based on vapor-phase photolysis studies,
where it was shown that TCE disappeared when irradiated with long
wavelength light in the presence of nitric oxide or nitrogen dioxide.
Dichloroacetic acid and hydrogen chloride are likely products. Photolysis
is, therefore., not expected to be an important loss mechanism for TCE
from water under environmental conditions.
4.3.2.4 Biodegradation
TCE is metabolized by higher organisms (Versar 1979) and its
metabolites (chloracetics) are readily degradable. (See Chapter 6.0).
However, microbial degradation does not appear to play a significant
role in the breakdown of trichloroethylene in the environment (HcConnell
1975, Wilson et. al. 1980).
4.3.2.5 Sorp t ion/De so rpt ion
Very little directly useful information is available concerning
sorption of TCE. The effects of clay and peat moss in a solution on
the evaporation of TCE from the solution were investigated (Dilling
e£ al. 1975). Dry granular bentonite clay exhibited a sorption partition
coefficient of ^300-375. (This coefficient was not derived by the
investigators but was derived from results presented in the paper.)
Other evidence (Versar 1979) shows no correlation between sorbed
concentration and water concentration. Coarse gravels have little
sorptive capacities. An octanol/water partition coefficient has been
reported (SRI 1980) to be 69.2 and an organic carbon partition coefficient
of 38 was derived from this value Versar (1979) reports a log
octanol/water partition coefficient of 2.29. An organic carbon parti-
tion coefficient of 100 has been derived from a regression equation
reported by Choiu et. al. (1979).
Monitoring data from the vicinity of plants manufacturing TCE show
concentrations in sediments to be similar to concentration in the water
from which sediment samples were taken (USEPA 1977a). This indicates
that little sorption occurs.
-------
The section on waste treatment (4.3.4.1) discusses sorption of ICE
onto sewage solids.
4.3.3 Fate in Soil
4.3.3.1 Transport and Volatilization
Wilson £t_ al. (1980) performed studies to determine transport and
fate of chemicals applied to soil; among these chemicals was trichloro-
ethylene. Most of the TCE in a water solution applied to a column of
sandy soil volatilized, while the rest percolated through a 140-cm
column. Little, if any, was biodegraded. Table 4-8 shows the soil
characteristics. Table 4- 9 shows test results. Soil columns were not
saturated.
In their comparison of volatilization from the soil column to
volatilization from water, Wilson et_ al. found that volatilization
from soil was inhibited by the soil by about a factor of ten. For an
initial concentration of 0.90 mg/1, the measured hourly flux from soil
was 0.34 ug/cm . Calculated flux from water was estimated to be
3.0 ug/cm3. For a volatile chemical such as TCE, volatilization is
probably limited by diffusion through air-filled pores.
Transport of TCE through the soil column, when defined as (inter-
stitial water velocity/velocity of pollutant), was inhibited minimally
by the soil. In a laboratory study using a sandy soil, the factor
was at most 1.6 + 0.2 and in field tests using a soil with a higher
organic carbon content, the factor was at most 3.1 (Wilson et al. 1980).
This increase in the retardation factor is probably due to sorption of
TCE onto organic matter.
The following conclusions can be drawn from Wilson e£ al. (1980):
• Most TCE applied to soil will volatilize.
• TCE percolating through the soil column is minimally retarded
by sandy soils. Organic matter increases the retardation rate
somewhat.
• Volatilization from the soil column occurs at a rate about ten
times lower than in a water column of similar depth.
4.3.3.2 Decomposition
Versar (1979) indicated that some organochlorine compounds
degrade more rapidly in the presence of metallic iron than in an iron-
free situation. This observation was mentioned in connection with life-
times in water, but it may have some significance for TCE in soil as
well. No rates or supporting data were included that would allow the
importance of this observation to be assessed. No trichloroethylene
degradation is assumed to occur in soil.
4-18
-------
TABLE 4-8 COMPOSITION OF SOILS USED IS STUDIES OF TRICHLOROETHYLENE
FATE IN SOIL
Laboratory Column Tests Field Tests
Sand
Silt
Clay
Organic
Carbon
Average
92
5.9
21
0.08
% Range
(95-89)
(8.0-4.0)
(3.5-1.5)
(0.22-0.02)
Average
76
5.7
19
0.13
% Range
(91-64)
(9.4-3.0)
(33-2.6)
(0.25-0.05)
Source: Wilson et al.(1980)
4-19
-------
TABLE 4- 9 FATE OF TRICHLOROETHYLEXE APPLIED TO A SOIL COLUMN IN THI
LABORATORY
Concentration Applied, % in Column % Degraded or
mg/1 % Volatilized Effluent not accounted for
0.90 59+14 28+1 14 + 15
0.18 90 +18 21 + 13 -10 + 11
Source: Wilson et al. 1980
4-20
-------
4.3.4 Other Fate Processes
Trichloroethylene is found in sewage and Che effluent from sewage
treatment plants. It is also found in landfills from waste deposited
in the landfills. These are important routes for TCE input into the
environment because of their potential effects on ground and surface
waters. This section discusses TCE behavior in solid waste and in
sewage treatment.
4.3.4.1 Waste Materials
Jones et_al. (1977/78) performed experiments in which a TCE
solution was mixed with fresh, untreated domestic refuse from a landfill.
The refuse leachate was monitored over a period of a few months to
determine TCE concentrations in the leachate.
A TCE preparation (Triklore) was mixed with equal volumes of used
crankcase oil. The solution was mixed with the refuse to give 200 mg/kg
and 500 mg/kg concentrations of TCE. Three canisters were prepared for
each TCE concentration. One was left uncovered, one was closed, and
one was fully saturated with water. All were left outdoors. '
Only the leachate from the 500 mg/kg closed column and the 500 mg/kg
fully saturated column contained >2 mg/kg concentration of TCE. Leachate
from the closed column contained 4-7 mg/kg of TCE over a 4-month elution
period, and 9-13 mg/kg was detected in leachates from the saturated
column over a similar time period. None was detected in the open column
or the 200-mg/kg columns.
These experimental results indicate that evaporation and adsorption
may result in leachate concentrations of TCE that are about two orders
of magnitude lower.than the initial concentration in the domestic waste
being leached.
Anaerobic digestion is inhibited by TCE at 200-1200 mg/kg dry
solids (Camisa 1975). In an activated sludge system, 300 mg/l caused
little repression of the glucose removal rate. More than 300 mg/l
caused slight repression, and more than 500 mg/l caused significant
repression of bacterial activities and partial inhibition of enzymes.
TCE partitions into the sludge. The maximum concentration expected
to sorb onto sludge is 3030 mg/kg dry solids. This concentration has
the potential to affect anaerobic digestion adversely.
Camisa (1975) determined the partitioning of TCE among several
different components of sewage, wet sludge, settled sewage, raw sewage,
and dry solids. The results are shown in Figures 4-3 to 4-5 and
Table 4-10.
4-21
-------
1000
8
0
w
> 100
cc
O
\
y
" 10.
/
/
/
/
!
»/
1
X
^
/'
"
1
L
t
j
i
j
t
i
1 1
OJ 1,0 10.0
MC TCE/LITER SETTLED SEWAGE
Source: Camisa 1975
FIGURE 4-3 CORRELATION BETWEEN TRICHLOROETHYLENE IN DRY SOLIDS
AND THAT IN SETTLED WASTEWATER FROM SEWAGE TREATMENT
10
Id
?.
•
5 LO
£
UJ
K
_l
U
*
O
" Ql
— ?
/
/
/
i
r
•
^
i
t :
/
f
T
i /"
i
i
!
: ' '
i j
!
!
!
r,
i
— :
i
i |
i
1
! !
;
j i
i
i
10 IQO
MG TCE/LITER RAW SEWAGE
Source: Camisa 1975
FIGURE
CORRELATION BETWEEN TRICHLOROETHYLENE IN
WET SLUDGE AND THAT IN UNTREATED SEWAGE
4-22
-------
U
O
U
O
go
9
8
sruor
11 Illl I I I I I Illl
I I I I Illl I I I I 11II
OJ i iO PC -^~
SOLUTE TCE CONCENTRATION MC/LITER
Source: Camisa 1975
FIGURE 4-5 PLOT FOR MAXIMUM TRICHLOROETHYLENE
SORPTION ON DRIED SLUDGE SOLIDS
TABLE 4-10 TRICHLOROETHYLENE ADSORPTION ONTO SLUDGE-DATA SUMMARY
»«TCE
•dried to
201
3,962
7,925
11.888
15.850
21.632
28,540
34.832
38,974
40.369
i
mcTCF-l <
raw , •>
wanewuer i
•
0.198 i
0.396 :
0.594 ,
0.792 i
1.08 :
1.42 '
1.74 '
1.94 :
2.01 i
I
S-ttled Volume of
Imlue (•-(} ' 3JJJJJ
1
2.36
2.30
2.72
2.10
2.40
2.51
2.82
3.10
275
i
\\Vishiof . us of TCE
lined Miitiue i recovered
II) : ir. riuiise*
.... . 121
160 ' 3.68 1 161
200 I 5.44 ! 408
140
2.96
240 5.77
248 > 6.24
169
278
2.90 i 178
1
4.79
8.62
5.18
287
877
1.297
1,163
2.473
1.693
i .B of TCP.
1 recovered in
1 natant*
j
! 4,097 1
! 6.136 1
I 9.945 i
1 12.037 ;
! 16.948 '
: 23.562 .
1 27.992 1
! 33.617 j
I 35.084 I
: i
me TCK ks '
ariril
-------
TAI11.G 4-11 TRICtll.OKOimm.KNK CONCENTRATIONS AT VARIOUS STACKS or WASTKWATKR TKKATMKNT
_ J JIB/A_) TCE Concentration (life / L ;
I'lant
1
2
3
4
5
6
JN
K ?
I'Jant
a
8
9
9
Effluent
In fluent Pre-Ci.
28 5
2 0
2 1
497
49
487
17 4
Stage
Total Fnfluent
Secondary Kf fluent
(Chlorinated)
Total Influent
Secondary Kf Fluent
Gravity Heat- Heat-
Final Z Primary Combined Thickener Treated Treated
Effluent Kern. Sludge Sludge Overflow Sludge Decant
4 86 284
0 100 - <5
<5 100 38 - 3
37 93 - 467
14 71 163
64 87 30
76 - 2 7 <5
Times %
Analyzed Delected Detected Average Minimum Maximum
4 4 100 30 11 78
4 1 25 0 <2 \
6 6 100 33 1 51
N\)n m*H tin" ND€M Ni>n ND"
DilU'K
SLnd£<
120
2
4
(Chlorinated)
Not l»eI «•<-led.
Son ret-: liurns and Koe (1980)
-------
Barrett (1972) investigated ICE in the gas from a sewage digester.
ICE concentrations in the gas peaked immediately after the addition of
ICE and then dropped steadily. Barrett (1972) attributed this behavior
to the ability of the digester to digest the solvent, but it also seems
plausible that the concentration in the gas was dropping due to depletion
of TCE in the waste by volatilization. Barrett (1972) did note that
some of the solvent was stripped out by the gas during digestion, somewhat
confirming Camisa's (1975) results.
Barrett (1972) determined that in a digester with a 20-day retention
period, the digester could survive shock doses of 1200 mg TCE/1 sewage.
This value is much higher than the 1C-60 mg/1 concentrations reported
to cause inhibition of anaerobic digestion by Versar (1979) (4.3.2.4)
Data from U.S. EPA (1976) show TCE concentrations in water from
sewage treatment plants in several cities to be 40.4 mg/l in influent
before treatment, 8.6 mg/1 in effluent before chlorination, and 9.8 rag/1
in effluent after chlorination. Other data from a recent study (Burns
and Roe 1980) give TCE concentrations for nine plants at various stages
during the wastewater treatment process. As shown in Table 4-11,
between 70% and 100% of the TCE appears to be removed between influent
and effluent.
4.4 ENVIRONMENTAL FATE MODELLING
4.4.1 Overview
The environmental fate of trichloroethylene was analyzed through
the use of mathematical models. These models are useful to indicate the
behavior of chemicals in the absence of measured environmental processes
or concentrations. The methods also are useful in estimating ambient
concentrations under other circumstances, e.g., a reduction in environ-
mental releases or different environmental conditions.
A fugacity model was used to estimate equilibrium concentrations
in a river-basin-sized region. The EXAMS model was used to investigate
TCE behavior in water.
4.4.2 Equilibrium Model
Concentrations in air, water, and soil were compiled using a Level
II fugacity model (Mackay 1979). Fugacity can be regarded as the
"escaping tendency" of a chemical substance from a compartment. When
the escaping tendencies, the fugacities, from two or more compartments
are equal they are in equilibrium and there is no net movement between
compartments. The fugacities are proportional to concentrations;
hence, chemical concentrations in each compartment can be estimated.
Table 4-12 shows the input data used.
The fugacity coefficients, fugacity. masses in each subcoir.parttr.ent,
and concentrations ... each compartment were calculated. These are
shown in Table 4-13.
4-25
-------
TABLE 4-12 DATA USED IN LEVEL II
Volume of the air compartment
Volume of the water compartment
Volume of the soil compartment
Density of soil
Organic carbon content of soil
Temperature
Advection
Henry's Lav Constant
K
oc
Molecular Weight
Photooxidation Rate Constant
Other rate constants (soil, water)
Input rate to compartment
FUGACITY CALCULATIONS a
2.6 x 10Um3 (1 km depth)
1.04 x 1010=3 (1 a depth)b
2.6 x 1010m3 (10 cm depth)
2 x 106 g/m3
15%
20'C
None
0.0095 atm-m /mole
100
131.4 g/mole
k • 510 yr"1
k2, k3 = 0
I « 3.12 x 10 moles/yr
(4.1 x 106 kg/yr)
Some input data are assumed values; some data are from the literature
and are discussed in the appropriate sections.
Water covers 4% of the region. Average water depth was arbitrarily
assumed to be 1m since no data were found concerning stored water
in the region.
4-26
-------
TABLE 4-13 ESTIMATED TRICHLOROETHYLEKE CONCENTRATION IS AIR, WATER AND SOIL
DETERMINED BY FUGACITY CALCULATIONS
Sub-
Compartment
Air
Water
Soil
Fugacity
Coefficient
41.6 mol/m a cm
105.3
3158
Mass In
Subcompartment
8040 kg
0.8 kg
60 kg
Concentration
In Subcompartaent3
30 ng/m
0.08 ng/1
1.2 ng/kg
Z = 8100 kg
Rate of removal from air — 4.1 x 10 kg/yr
Average Residence Time of TCE in the compartment — 0.72 days
under equilibrium conditions the ratios between concentrations in the
three media are independent of the volumes assumed for the media.
4-27
-------
Reductions in emissions are reflected linearly in reductions in
concentrations. Hence, a reduction by one third in emissions results in
a similar reduction by one third in ambient equilibrium concentrations.
A.4.3 EXAMS
For the purpose of examining the probable fate of TCE in various
aquatic environments under conditions of continuous discharge, the
EXAMS (Exposure Assessment Modelling System) model AETOX 1 was imple-
mented (USEPA 1980b). Rate constants and physical/chemical properties
thought to influence the fate of TCE in the water environment are
presented in Table 4-14 (SRI 1980). An arbitrary loading rate of
1.0 kg/hr was chosen for purposes of comparing different systems. Six
prototype systems were simulated to provide a range of environmental
conditions: pond, eutropic and oligotrophic lakes, and rivers (average,
turbid and coastal plain).
As would be expected, in relatively static systems (ponds and lakes)
in which physical transport processes did not dominate, volatilization
was the most important removal mechanism, responsible for a 93-96%
loss of the equilibrium TCE mass. Table 4-15 presents information on
the distribution and transformation of TCE in the different systems.
In all the river systems, (1 km segments) transport downstream alone
accounted for at least 85% of the removal, and at a much faster rate
than volatilization (on the order of hours rather than days). The
overall time for self-purification (following cessation of discharge)
was, thus, over 2 months for the lakes, approximately one month for the
pond and less than 2 days for the rivers.
In order to provide a better understanding of the fate of trichloro-
ethylene continually discharged into a river (flow • 2.4 x 10' nrVday,
depth » 4 m), the EXAMS river system was modified by extending its
length by various increments from 2 km up to 1000 km from the point
source. At approximately 50 km downstream, slightly more than 50%
of the total mass had volatilized, a negligible amount had oxidized,
and the remainder was transported further downstream. One hundred km
downstream, 75% of the total amount had volatilized, and by 500 km
downstream, about 98% was volatilized. Chemical oxidation had little
effect on TCE concentration; even at 1000 km downstream; the fraction
of the total mass lost via this process was <1%.
Table 4-16 presents the simulated TCE concentrations in different
environmental compartments (water column, sediment, plankton and benthos)
at steady-state conditions. Water concentrations were approximately
0.1-3 mg/1 in the pond and lake systems and considerably lower (due to
dilution and flow rates), 1-10 ug/1, in the river systems. Sediment
concentrations were variable, ranging from "-0.3 pg/kg up to about
5000 yg/kg. The highest levels were in the pond where both volatilization
and physical transport were not fast enough to remove TCE before a
slight accumulation above water column concentrations could occur.
4-28
-------
TABLE 4-14 PARAMETERS FOR TRICHLOROETHYLENE USED IN EXAMS ANALYSIS
Property
Molecular Weight
Solubility
Liquid Phase Transport Resistance
Henry's Law Coefficient
Vapor Pressure
Partition Coefficient:
• Biomass /Water
• Sediment/Water
• Octanol/Water
Chemical Oxidation Rate Constant
• Water
• Sediment
Value
131.4
1100
0.548
9.1 x 10~3
57.9
11.4
38.0
69.2
6.0
1 x 10"3
Units
g/mole
mg/1
unitless ratio
3
m /mole
torr
•
ug/g
mg/1
mg/kg
mg/1
ma, 1
mg/1
mole/1 /hr
mole/1/ hr
aAll data from SRI (1980).
4-29
-------
TABLE 4-15 TUB PATE OF TRICIILOROETUYLENE IN VARIOUS GENERALIZED AQUATIC SYSTEMS8
System
Pond
Ku trophic Lake
Ollgotrophle Lake
River
1
U> Turbid River
Coastal Plain
Residing In
Water at Steady-
State
93.3
>99.9
>99.9
99.2
99.4
98.5
Residing In
Sediment In
Steady-State
6.7
4fl 1
-------
TABLE 4-16 ESTIMATED STEADY-STATE CONCENTRATIONS IN VARIOUS GENERALIZED AQUATIC SYSTEMS RESULTING FROM
CONTINUOUS TRICIILOROETHYLENE DISCHARGE AT 1.0 kg/hr*
Maximum In
Water— Water— Rotten Sediment Total Steady Total
Dissolved Total Sediment Deposits Plankton Benthos State Accunula- Dally toad
System Loading (ng/l) (ng/1) (nut/1) (DK/K) (UR/B) (UK/K) tlon (kg) (kit/day)
Pond 1.0 kg he"1 2.5 2.5 1.3 5.3 28 14 S3 24
Eu trophic
Lake
Ollgotrophlc
Lake
River
Turbid
River
Coastal Plain
River
0.13 0.13 4.3 x 10° 7.8 x 10"3 l.S 4.9 x 10~2 310 24
0.14 0.14 1.6 x 10~3 3.0 x 10~3 l.S 1.8 x 10~Z 350 24
9.9 x 10~* 9.9 x 10~* 3.3 x 10~* 9.3 x 10~* 1.1 x 10~2 3.7 x 10"3 0.89 24
9.9 x 10~* 9.9 x 10~* 6.5 x 10~* 7.4 x 10~* 1.1 x 10~2 7.5 x 10~3 0.89 24
9.3 x 10~3 9.3 x 10"3 3.1 x lo"3 1.3 x lo"2 0.11 3.6 x 10"2 8.0 24
*All data simulated by EXAMS Model (see text for further Information).
-------
Concentrations in biota were generally one to two orders of magnitude
above water levels which is compatible with observed bioaccumulation
levels (see Section 6.2 for a discussion of biological fate).
Based on the results of the EXAMS run and dependent on the
assumptions of the Model and the rate constants used as input, some
conclusions can be drawn about ICE's potential behavior in water. In
relatively static systems with slow flow rates (e.g. lakes) TCE's
persistence is a function of volatilization. In more dynamic river
systems, physical transport processes are much more competitive for
ICE, transporting the chemical over a considerable distance before
volatilization can remove a significant amount from a segment of the
river. Transformation processes and bioaccumulation will not significantly
reduce water concentrations. The sediment layer does not appear to
absorb TCE at levels much above water concentrations; in fact, these
levels are sometimes lower than water levels. Since volatilization is
such an important fate mechanism, then conditions such as high temperature,
high wind speeds, and high water turbulence would increase removal due to
volatilization.
4.5 SUMMARY
Trichloroethylene appears in all environmental media - air, water
(including groundwater), and soil. Concentrations detected in the »
atmosphere range from a background level of 27-100 ng/m to ^1.5 mg/m
in the vicinity of TCE production sites. Concentrations detected in
surface water range from none to 188 ug/1. When detected in surface
water, however, TCE is generally found at a concentrations on the order
of 1-10 wg/i. In groundwater, concentrations up to 35 mg/1 have been
detected, but monitoring surveys indicate concentrations to be mostly
in the <1-100 ugA range. Data on only a few soil samples were found.
These showed soil concentrations between.none detected and <10 ug/kg
(dry weight). Data concerning concentrations in sediments are too few
to indicate specific sorption characteristics, although TCE does sorb
and has been found in sediments.
The environmental fate of trichloroethylene has been assessed.
TCE is highly, volatile. Its half-life in surface waters is estimated
to be on the order of a few hours to a few days, depending upon the
characteristics of the water body. TCE also volatilizes from soil if
exposed to the air although estimates of the volatilization rate are
imprecise. The process does appear to occur up to ten times more
slowly than from water of a depth similar to that of the affected soil
volume. The ultimate disposition of TCE appears to be atmospheric
photooxidation. Half-life in the atmosphere due to photooxidation is
estimated to be about 1 day,with a possible range from 12-48 hours.
TCE does not undergo other chemical fate processes to any appreciable
degree. Based on this information, the ultimate fate of TCE is expected
to be destruction by atmospheric photooxidation following direct emission
or volatilization from water or soil.
4-32
-------
Fate processes have been modelled for an environmental situation.
The results of the model agree fairly well with monitoring data. Back-
ground air concentration under current release conditions is about
30 ng/m , while in water and soil ambient concentrations are negligible,
less than 1 ug/1 and 1 ug/kg, respectively,
This positive evaluation indicates the usefulness of the model in
estimating environmental concentrations. Ambient concentrations due
to changes in emissions have been estimated using the model. The model
used shows the emission reductions are reflected linearly in reduction
of ambient equilibrium concentrations. Hence, a reduction in emissions
by one third or one half results in a similar reduction in environmental
concentrations.
The EXAMS model showed that volatilization was the most significant
removal mechanism for TCE in water bodies. In the river system analyzed,
half of the TCE had volatilized in 50 km downstream, and 98% was gone
500 km downstream. Other fate mechanisms contributed minimally to the
loss of TCE from the water.
4-33
-------
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Battelle Columbus Labs. Environmental monitoring near industrial sites -
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organohalides in chlorinated drinking waters. Report No. 670/4-74-008,
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Brass, H. J.; Feige, M. A.; Halloran, T.; Mello, I. M.; Munch, D.;
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analyses for purgeable organic compounds. Pojasek, R. B. ed. Drinking
water quality enhancement through source protection. Ann Arbor MI.
Ann Arbor Science Publishers; 1977, Chapter 23.
Burns and Roe, Inc. Preliminary data for POTW studies. Washington, D.C.:
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Camisa, A. G. Analysis and characteristics of trichloreothylene wastes.
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Chiou, C. T.; Peters L. J.; Fried, V. H. A physical concept of soil-
water equilibria for nonionic organic compounds. Science 206(4420)831-2;
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Congilio, W. A.; Miller, K.; Mackeever, D. The occurrence of volatile
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Cox, R. A.; Derwent, R. G.; Eggleston, A. E. J.; Lovelock, J. E. Photo-
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Cronn, D. R.; Rassmussen, R. A.; Robinson, E.; Harsch, D. E. Halogenated
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Dahlberg, J. A. The non-sensitized photo-oxidation of trichloroethylene
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Dickson, A. G.; Riley, J. P. The distribution of short-chain halogenated
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Dilling, W. L. Interphase transfer process II. Evaporation rates of
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Dilling, W. L.; Tefertiller, N. B.; Kallos, G. J. Evaporation rates
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chemistry simulated atmospheric photodecomposition rates of methylene
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Grimsrud, E. P.; Rasmussen, R. A. Survey and analysis of halocarbons
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Jones, C. J.; Hudson, B. L.; McGugan, P. J.; Smith, A. J. The leaching
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Jungclaus, G. A.; Lopez-Avila, V.; Kites, R. A. Organic compounds
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Mackay, D. Finding Fugacity feasible. Environ. Sci. Technol. 13:1218-1223;
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4-38
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5.0 EFFECTS AND EXPOSURE—HUMANS
5.1 HUMAN TOXICITY
5.1.1 Introduction
The human health effects of trichloroethylene have been investigated
extensively, and several comprehensive reviews on the toxicity of ICE are
available (MRI 1979; Waters et al. 1976; USEPA 1979; NIOSH 1973, 1978;
NAS 1977; von Oettingen 1964; Browning 1965). Therefore, this chapter
focuses on the data that provide the most useful assessment of acceptable
limits of human exposure to TCE and the consequences of such exposure.
5.1.2 Metabolism and Bioaccumulation
5.1.2.1 Absorption and Distribution
Trichloroethylene can be absorbed by inhalation, ingestion, or
cutaneous exposure. Inhalation is the most important route of entry.
Persons inhaling TCE will retain between 50% and 76% and eliminate the
remaining TCE unchanged (von Oettingen 1964, Bauer and Rabens 1977,
Bartonicek 1962).
Numerous cases of human poisoning following ingestion of TCE attest
to its absorption from the gastrointestinal tract (Waters ejt al. 1976,
MRI 1979). Rats administered an oral dose of TCE expired 72-85% in air
and 10-20% in urine. This indicates extensive absorption from the
gastrointestinal tract (Daniel 1963).
Though TCE has been demonstrated to penetrate intact skin, it is
considered unlikely that absorption of toxic quantities would occur by
this route. Stewart and Dodd (1964) detected TCE in alveolar air
following insertion of a person's thumb in TCE for 30 minutes. The
mean peak of TCE in expired air was 2.69 mg/m3.
Sato and Nakajima (1978) observed the effects of immersion in TCE
of one hand by each of four healthy males wearing self-contained breathing
apparatus. The end tidal air concentrations for the first 2 hours
following a 30-minute immersion were approximately, twice as high as the
concentrations noted after inhalation of 538 mg/m TCE for 4 hours.
This occurred even though uptake through skin was approximately one-
third of uptake by inhalation.
In mice, percutaneous absorption of TCE was found to increase linearly
with time over a period of 5 - 15 minutes (Tsuruta 1978). An in vivo
absorption rate of 7.82 ug/min/cm2was determined. The penetration rate
may be somewhat higher since all TCE metabolites were not determined. .
The penetration rate with excised skin was calculated to be 12.1 yg/min/cm .
If a similar absorption rate is assumed for man, immersion of both hands
5-1
-------
2
(^800 cm ) into TCE for 1 minute would result in the absorption of
approximately 6.3 - 9.7 mg TCE, or approximately one- third the uptake
that would result by inhalation.
Following absorption, the blood transports TCE to body tissues. The
mechanism of this transport is unknown. Because of its lipid solubility,
TCE that is not immediately metabolized may be extracted from blood by fatty
tissue (Waters et^ al . 1976). TCE metabolites are known to bind irreversibly
to sulfhydryl groups in vivo and, to a lesser extent, to free amino
groups of proteins, with the greatest protein binding seen in the liver
(Bolt and Filser 1977) . Van Duuren (1977) noted that the in vitro binding
of TCE to liver microsomal proteins of male B6C3F1 mice was significantly
higher than that seen in male Osborne-Mendel rats. Furthermore, the
binding was higher in male mice than in female mice. The significance
of these data will be discussed in the carcinogenicity section (See
Section 5.1.3.1).
5.1.2.2 Biotransformation and Elimination
Several metabolic pathways have been suggested for TCE. The generally
accepted pathway based on known metabolic products and possible inter-
mediates is shown in Figure 5-1. Although the fraction of various
eliminated metabolites differs, the overall pattern appears similar for
the various mammalian species studied. The first step involves oxidation
of TCE to chloral hydrate via an epoxide intermediate; the epoxide is
believed to undergo spontaneous intramolecular rearrangement to form
trichloroacetaldehyde, which is subsequently hydrolyzed to the sedative-
hypnotic, chloral hydrate (Daniel 1963, Waters et_ al . 1976, Van Duuren
1977, Nomiyama and Nomiyama 1979b) . Oxidation or reduction rapidly converts
chloral hydrate to trichloroacetic acid (10-36%) , or trichloroethanol
(32-59%), respectively. Trichloroethanol is conjugated with a slucuronide
and excreted in the urine in the same way as trichloroacetic acid and
a minor metabolite, monochloroacetic acid (4%) (Leibman 1965, Soucek and
Vlachova 1960, Bauer and Rabens 1977).
Parchman and Magee (1980) reported the production of 1^C02» a
previously unreported metabolite of TCE, in male Sprague-Dawley rats
and male B6C3F1 mice injected intraperitoneally with low doses of
14C-TCE (0.2-6 mg/kg). Approximately 70% of the label was excreted in
urine within 6 hours; by 24 hours, 10% of the label was recovered as
14C02. Injection of higher doses (1.5-3 g/kg) produced "little C02,"
an observation suggesting dose-related differences in metabolite pathways.
The rate of conversion of TCE to chloral hydrate is relatively
slow; once chloral hydrate is produced, however, the biotransformation
of chloral hydrate to trichloroethanol and trichloroacetic acid proceeds
so rapidly that chloral hydrate cannot be detected in plasma (Nomiyama
and Nomiyama 1979b) . For example, Marshall and Owens (1955) detected no
chloral hydrate in human plasma 5-30 minutes after ingestion of 30 rag /kg
chloral hydrate. Trichloroethanol has a biological half-life of x!3 hours
5-2
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Figure 5-1 Metabolism of Tricliloroetliylene in Animals and Man
Ul
to
Cl
\
V
mixed
function
oxidases
Cl II
NADPII
2
Cl Cl
\ /
Cl-C-C-ll
\/
Tr Lchloroethylene
V
II
I ^o
c-c-c
I x»
II
Monocliloracetic
acid
Tricliloroetliylene
oxide
Cl Oil
\ I
Cl-C-C-ll
\
NADU
alcohol
dehyrogenasc
Cl OH
Chloral
hydrate
spontaneous
intramolecular
rearrangement
Tr ichlorocthanol
glucuronyl
transferase
I I
CI-C-C-O-C.ILO
I I 696
CL II
hydrolysis
Tr i ch Loroacetaltlehydi:
dehydrogcMtaso
NAD
mixed function
oxidascs
O
TrichJoroaccit Jc
acid
llrocliloral Ic acid (Triclilorocthanol j;1 neuron Ide)
-------
in humans compared with a value of 50-90 hours for trichloroacetic acid.
Thus, excretion of urochloralic acid is rapid compared to the slower
rate of excretion for trichloroacetic acid, presumably as a result of high
protein-binding affinity of the acid (Muller et_ al. 1974). Ikeda (1977)
found a linear correlation between the concentration of TCE in the work
environment and the level of total trichloro-compounds in urine. The
trichloroechanol level was also linearly related to the TCE concentration,
while trichloroacetic acid levels deviated frcm the linear relationship
when the TCE level exceeded 268 mg/m3.
Monster _et_ al. (1976) exposed four male volunteers either at rest
or rest combined with exercise to 376 or 753 mg/nr TCE for 4 hours at
3-week intervals. These experiments indicated that the concentration
of TCE and trichloroethanol in blood and expired air were proportional
to the dose. Workload increased the mean dose by approximately 40%;
however, it did not influence distribution or metabolism. After 66 hours,
67% of the dose was recovered: 10% exhaled as TCE and 57% eliminated in
urine as trichloroethanol (39%) and trichloroacetic acid (18%). Similar
results were obtained by Astrand and Ovrum (1976) in a study with 15
healthy men exposed to 538-1076 mg/nr TCE during four 30-minute rest-
exercise periods.
Nomiyama and Nomiyama (1979a) examined the metabolism of TCE in
man, rabbits, and rats. Five male students were exposed to 1345-2044
(mean 1695) rag/or TCE for 160 minutes (equivalent to 25 mg/kg intake
of TCE); three male rabbits and five male rats were injected intra-
peritoneally with 200 and 50 mg/kg TCE, respectively. [Ikeda and
Ohtsuji (1972) have shown that the route of administration does not
modify the metabolism of TCE in the rat]. Urinary excretion of trichloro-
ethanol and trichloroacetic acid decreased exponentially in the three
species studied; however, the rates of decrease differed. These rates
were considerably lower in man, with large amounts still detectable
6 days after exposure. In rats, the rate of decrease was rapid, with
metabolites barely detectable at 3 days. The ratio of trichloroethanol
to trichloroacetic acid also indicated differences in TCE metabolism
among the three species: 207, 12.5 and 1.9 for rabbit, rat,and man,
respectively. Trichloroethanol was the major metabolite in rabbits,
while the reverse was true in man. Trichloroacetic acid has also been
detected in the urine of dogs (von Oettingen 1964).
Nomlvama and Nomiyama (1971) reported that the pattern of TCE
metabolism differed between men and women; i.e., within the first 24
hours following exposure to 1345- 2044 mg/m TCE in air, women tended
co excrete more trichloroacetic acid and less trichloroethanol than
males. A similar study with rats showed no significant differences
between sexes in TCE metabolism (Nomiyama and Nomiyama 1979a). Man
also appears to exhibit an age-dependent pattern of TCE excretion.
Grandjean e_t al. (1955) reported that younger workers excreted more
inhaled TCE as urinary trichloroacetic acid than in expired breath
(6:1 ratio) in contrast with the ratio in older workers (2:1), suggesting
an age dependence for urinary:alveolar excretion of TCE.
5-4
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Little information is available on the accumulation of TCE in human
tissues. McConnell e_t. al. (1975) reported that post-mortem samples of
human tissues from eight individuals with unknown exposures to TCE con-
tained less than 1-32 ug TCE/kg wet tissueiwith no significant pattern
of distribution or accumulation evident.
5.1.3 Human and Animal Studies
5.1.3.1 Carcinogenicity
Considerable controversy exists concerning whether TCE is carcinogenic.
The available evidence presented in this section is insufficient to
indict pure TCE as a carcinogen, but does suggest that technical grade
TCE may be a potential, but apparently weak, carcinogen. Test data
from studies under way are needed to clarify this issue.
No epidemiologic evidence suggests that TCE exposure is associated
with an increased risk of cancer in humans. Preliminary analysis in
two cohort mortality studies in Sweden and Finland suggests no increased
risk of cancer; however, data are presently insufficient to analyze
site-specifically for cancer risk (Axelson e£ al. 1978, Tola 1977).
The National Cancer Institute (1976) reported that the oral
administration of time-weighted-average doses of 2339 and 1169 mg
technical grade TCE/kg bodyweight (bw) in male and 1739 and 869 mg TCE/kg bw
in female B6C3F1 mice, 5 times per week for 78 weeks,induced a significant
increase in hepatocellular carcinoma:
Males Females
Control 1/20 (5%) 0/20 (0%)
Low Dose 26/50 (52%) p = 0.004 4/5 (8%) p = 0.090
High Dose 31/48 (65%) p <0.001 11/47 (23%) p = 0.008
Hepatocellular carcinoma was detected as early as 27 weeks in males at .
the high dose level, but developed later in low-dose males and all
females.
No carcinogenic effect was observed, however, in a concurrent study
with Osborne-Mendel rats exposed five times per week by gavage to time-
weighted average doses of 1097 and 549 mg technical grade TCE/kg body weight (bw)
Increased mortality necessitated a reduction in dosing to a 4-week
treatment, with a 1-week no treatment regimen. The mortality rate reduced
the ability to detect TCE-induced carcinogenicity in Osborne-Mendel rats.
This strain also showed a poor response (5% hepatocellular carcinoma)
to the positive control, carbon tetrachloride (NCI 1976).
Negative carcinogenic effects were observed in Sprague-Dawley rats
administered 24 or 240 mg highly purified TCE/kg by gavage, 4-5 days/week
for 52 weeks, then held up to 140 weeks (Maltoni 1979). Maltoni (1980)
5-5
-------
reported a negative carcinogenic response in mice (strain unspecified)
fed 500 mg highly purified TCE/kg bw 5 times/week for 52 weeks. So other
details were available. In another study with mice, Rudali (1967)
observed no liver lesions or hepatomas in 28 NIC mice (age unspecified)
given 40 mg TCE in oil/mouse by gavage twice weekly for an unspecified
period. The positive control, carbon tetrachloride,produced a good
response in this strain.
Van Duuren and coworkers (1979) intubated Ha:ICR Swiss mice with
a highly purified sample of 0.5 mg TCE/mouse, once a week for the
duration of a 622-day study. No significant increase in forestomach
tumors was found; only lung, liver and stcmach were examined histologically.
Repeated dermal application of highly purified TCE (1 mg in acetone/
mouse, 3 times/week for 581 days) to the dorsal skin of Ha:ICR Swiss
mice produced no significant incidence of skin tumors (Van Duuren et_ al.
1979). A similar experiment involving an initiation-promotion sequence,
i.e., a single application of TCE followed by repeated applications of
the tumor promoter, phorbol myristate acetate, also produced negative
results (Van Duuren et al. 1979).
The Manufacturing Chemists Association sponsored Industrial Bio-
Test Laboratories, Inc. (IBT) to do a 2-year inhalation study with
Charles River rats and B6C3F1 mice. These animals were exposed to
538, 1614, or 3228 mg technical grade TCE/m3, 6 hours/day, 5 days/week
for 24 months. The TCE used in this study was identical to the TCE
sample used in the NCI (1976) study. Preliminary results of mice
killed at 24 months and rats dying by 21 months indicated an apparent
induction of liver cancer in mice but no evidence of tumors in rats
(Clark 1977 a,b,c). This study has been criticized because exact con-
centrations of TCE administered were not known (analytical data indicate
extreme deviations from nominal concentrations) and because the control
animals were obtained from a different population (Infante and Marlow 1980).
No carcinogenic effects were reported for Han:Wist rats, Syrian
hamsters or male Han:NMRI mice exposed to 0, 538, or 2690 mg purified
TCE vapor/m , 6 hours/day, 5 days/week for 18 months. Surviving mice
and hamsters were killed at 30 months and rats were killed at 36 months.
An elevated incidence of malignant lymphoma was noted in treated female
mice (17/30 low dose, 18/28 high dose vs. 9/29 controls). An immuno-
suppressive effect of TCE and/or its metabolites may be responsible
for the observed increase in lymphomas (Henschler et_ al. 1980). The
significance of this finding is open to question in view of the high
incidence of lymphoma in controls (31%). Another lifetime inhalation
study initiated in February 1979, with 3500 animals (Sprague-Dawley
rats and Swiss mice), is currently in progress (Maltoni 1980). Test
animals are being exposed 3228-18830 mg highly purified TCE/m3. No
carcinogenic effects were evident at 1 year. A second carcinogenicity
study for TCE by the oral route is also underway in B6C3F1 mice and
five strains of rats (Osborne-Mendel, Fisher 344, MA540, A28807, and
ACI); completion is expected by 12/81 (NCI 1980).
5-6
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Thus, other than the elevated incidence of lymphoraa in female
Han:NMRI mice exposed to purified TCE vapor for 18 months (Henschler
et_ al. 1980), which is of debatable significance in view of the 30%
incidence of lymphoma in controls, the sole carcinogenic response in
which the dose of TCE is clearly established, is hepatocellular carcinoma
noted in B6C3F1 mice given technical grade TCE by gavage for 78 weeks
(NCI 1976). Several questions on a number of points have caused concern
about the validity of these results (Henschler et^ al. 1977, Van Duuren
1978). Analysis (GC/MS) of the industrial grade TCE used in the NCI
study indicated that it contained two epoxide stabilizers (0.22% epichloro-
hydrin and 0.19% 1,2-epoxbutane), both of which are highly mutagenic in
the Ames assay (Henschler ^jt al. 1977, Weisburger 1977).
Henschler e_t al. (1977) believe that the carcinogenic effects noted
in the NCI study were predominantly, if not exclusively, due to the epoxides.
Limited feeding experiments with epichlorohydrin resulted in negative car-
cinogenic effects that were ascribed to epichlorohydrin's rapid rate of
hydrolysis at acidic pH encountered in the stomach (Van Duuren e_£ al.
1966). A co-carcinogenic effect of TCE and impurities, however, cannot
be ruled out.
Another issue concerning the NCI study is metabolic overload.
The toxic doses utilized in the NCI study may have partially chemi-
cally hepatectomized the mice, with tumorigenesis occurring secondary
to rapid cellular proliferation and liver regeneration; or, the
high dose levels may have saturated the usual metabolic pathways,
resulting in atypical metabolites and/or routes of metabolism.
Indeed, recent findings of Farchman and Magee (1980) suggest dose-
related differences in metabolic pathways for TCE; and Ikeda (1977)
found that the linear correlation between TCE exposure level and
trichloroacetic acid in human urine deviated from linearity when
TCE exceeded 268 mg/m3.
In addition, species differences are known to exist in hepatic'
epoxide hydrase activity, the enzyme that inactivates epoxides.
Hydrase activity in humans is four times that of mice, two times that
of rats (Oesch £££1. 1974). The in vitro binding of TCE to liver
microsomal proteins was found to be 37% higher in male B6C3F1 mice than
in female mice and 46% higher in male mice than in male Osborne-Mendel
rats. The data correlate with the carcinogenicity results of the NCI
study (Van Duuren 1977). Parchman and Magee (1980) also reported small
amounts of radioactivity in DNA extracted from livers of B6C3F1 mice
6 hours after administration of ^C-TCE possibly suggesting that a TCE
metabolite interacts with DNA.
The Carcinogen Assessment Group (1980) has taken the position that:
• the administration of technical grade TCE by gavage for
78 weeks induced a statistically significant incidence
of hepatocellular carcinoma in male and female B6C3F1 mice
(NCI 1976): and
5-7
-------
• findings that inhalation of technical TCE vapor for 24 months
showed a statistically significant increase in hepatocellular
carcinoma in male B6C3F1 mice (Clark 1977)
are sufficient evidence that technical TCE is a carcinogen. Furthermore,
CAG believes that a significant increase in malignant lymphoma noted in
female Han:NMRI mice exposed to purified TCE vapor for 18 months
(Henschler et al. 1980) is substantial evidence to indicate that purified
TCE is a likely human carcinogen and grounds for disregarding all
negative data. The CAG has discounted the. absence of a dose-response,
the absence of tumors in exposed rats, the effective partial chemical
hepatectomy produced in mice with the high doses of TCE used in the
NCI study and the very high incidence of lymphoma in female control
NMRI mice. Resolution of these points must await studies currently in
progress with purified TCE in various strains of rats and mice,
scheduled for completion by the end of 1981 (i.e., via gavage by the
National Toxicology Program and via inhalation by Maltoni and coworkers).
Estimates of the human risk associated with TCE exposure have been
calculated based on the NCI (1976) mouse data of a 50% incidence of
tumors in male mice given 1170 mg TCE/kg/day. Using a multi-stage
model and the observed hepatocellular carcinoma incidence in male mice
in the NCI (1976) study, the CAG (1980) estimated the dose-response
slope and risk to-an average 70 kg human from TCE exposure. The slope
of the dose-response curve was 1.26 x 10~2 (rag/kg/day)'1, with the
additional risk for a lifetime continuous exposure to 1 ug/nr TCE
of 3.6 x 10-6.
5.1.3.2. Mutagenicity
The mutagenicity studies conducted with TCE have produced contradictory
results. Price ejt al. (1978) noted transformation of Fischer rat embryo
cells (F1706) to tumor-producing cells following exposure to TCE. Sub-
cutaneous injection of transformed cells into newborn Fischer rats pro-
duced fibrosarcoma at the site of inoculation in all test animals within
55 days.
Ismailov and Ryskal (1976) reported that the addition of 0.01%,
0.03%, or 0.05% of trichloroethylene to the nutrient medium of Drosophila
melanogaster caused sex-linked recessive lethal mutations in the chromo-
somes of 3.2%, 7.7%, and 8.2% of the offspring, respectively.
Negative findings were recorded, however, in a dominant lethal study
with 15 male rats exposed bj inhalation to 161A mg TCE/nr, 6 hours/day,
5-8
-------
5 days/week for 9 months. Males were subsequently mated with two
untreated females/week for 8 weeks. Reproductive performances in TCE-
exposed rats were reported to be comparable with those of control rats
(Bell 1977).
In bacterial mutagenicity assays, weakly positive results were ,
found with Salmonella typhimurium TAlOO exposed for 7 hours to 8070 mg TCE/m ;
however, this occurred only when exposure was coupled with liver microsomal
activation (Simmon e£ al. 1977).
Similar results were noted by Bartsch et. al. (1979). Weakly
positive results were also reported in Escherichia coli K12 exposed to
434 mg TCE/1 but only when activated with a mouse liver microsomal fraction
(Greim et al. 1975).
Positive mutagenic activity has also been noted in the presence of
microsomal activation with the yeast Saccharomyees cerevisiae in both
gene conversion (fram'eshift and base-pair mutations) and mitotic
recombination assays (Shahin and von Borstel 1977, Bronzetti et al^ 1978,
Callen et al. 1980). Bronzetti and coworkers (1978) also noted a
positive host-mediated assay in _§_._ cerevisiae with mice given a single
gavage dose of ICE (400 mg/kg) or multiple doses over a 5-day period
(total dose: 3700 mg TCE/kg).
In summary, positive mutagenic results have been noted in bacterial
and yeast test systems. This occurred only if microsomal activation was
provided in a mammalian cell transformation assay. On the other hand,
negative results were reported in a dominant lethal assay with rats
exposed to 1614 mg TCE/m for 9 months.
5.1.3.3 Teratogenicity
Although TCE is not considered teratogenic, it may delay skeletal
maturation in rats. Schwetz et al• (1975) reported no teratogenic
effects or significant maternal or fetal toxicity in either Swiss
Webster mice or Sprague-Dawley rats exposed to 1614 mg TCE/m3 by
inhalation, 7 hours/day on days 6 through 15 gestation.
Similar findings were noted in Charles River rats exposed by
inhalation to 1614 mg TCE/m3, 6 hours/day on days 6 through 15 of
gestation. In addition, offspring of male rats similarly exposed for
9 months prior to mating exhibited no genetic changes in germinal cells
(Bell 1977). In another study, female Long-Evans hooded rats were
exposed by inhalation to 9684 + 1076 mg TCE/m3 according to one of
four treatment regimens:
• TCE 2 weeks before mating and during first 20 days of pregnancy;
• TCE before mating with filtered air during pregnancy;
5-9
-------
• filtered air before mating, TCE during pregnancy; and
• filtered air before mating and during pregnancy.
The group exposed only during gestation shoved a significant
elevation in skeletal anomalies (incomplete ossification of the sternum),
which is indicative of developmental delay in maturation rather than
teratogenesis. This treatment group also demonstrated an increased
incidence of displaced right ovary(18.6% vs. 6.3% in controls). Dams
exposed before mating and during pregnancy and those exposed before
mating alone produced offspring that experienced a reduction in post-
natal body weight from 20-100 days after birth. Behavioral tests
revealed no statistically significant differences between treated and
control animals as measured by general activity levels at 10 and 20
days of age. No indications of maternal toxicity or fetotoxicity
were seen in any treatment group (Dorfmueller .§£ al^ 1979).
5.1.3.4 Other Toxic Effects
Exposure to TCE has been associated with toxic effects on the
central nervous,cardiovascular, hepatic, acd renal systems. The pre-
dominant toxic manifestation of acute TCE exposure in man is depression
of the central nervous system. Reported symptoms include visual
disturbances, mental confusion, fatigue, tremors, dizziness, nausea
and vomiting following exposure to a concentration of 800 mg TCE/nr
for 2 hours (Browning 1965, Lloyd et al. 1975, MRI 1979). High acute
doses have produced cardiac arrhythmias, with deaths typically caused by
ventricular fibrillation and cardiac arrest (Tomasini 1976, Waters
et al. 1976). Pelka and Zach (1974) reported that accidental ingestion
of ^150 ml TCE resulted in acute renal failure, anuria, uremia, and
hepatic and cardiovascular damage. The lowest reported oral lethal dose
in man is 50 mg TCE/kg (RTECS 1977).. By inhalation, the lowest reported
lethal concentration was 16,140 mg/m for 10 minutes (MRI 1979). CNS
effects have been reported due to 860 mg TCE/m^ for 83 minutes (RTECS
1977). Prolonged skin contact may cause local irritation and blister
formation; paralysis of the fingers has been reported after repeated,
intermittent immersion of the hands in TCE (Lloyd et_ .al.. 1975).
The effects of chronic exposure to TCE in humans have not been
extensively studied; therefore, they are not well characterized.
Intolerance to alcohol, however, is a well-documented symptom of
repeated TCE exposure (Waters et. al^. 1976, NIOSH 1978). The mixed
function oxidases responsible for the metabolism of ethanol also
metabolize TCE. A competitive inhibition between TCE and ethanol for
the enzyme results in the depression of TCE metabolism and a subsequent
build up of TCE in blood. Muller et al. (1975) demonstrated that con-
current administration of ethanol and TCE (538 mg/m3 for 6 hours) resulted
in a 2 1/2-fold increase in the concentration of TCE in the blood of
human volunteers above that observed in the absence of ethanol and
a 3-4-fold increase in the amount of TCE in expired air.
5-10
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In laboratory animals, Che acute oral toxicity of TCE is low. Oral
LD50 values (lethal dose to 50% of the population) of 4920 mg/kg in
the rat (RTECS 1977), 3200 mg/kg in the mouse (Klaassen and Plaa 1966),
and 2800 mg/kg in the dog (Klaassen and Flaa 1967) have been reported.
Adams et_ al. (1951) reported that the maximum concentrations of
TCE producing no toxic effects after exposure for 7 hours/day, 5 days/
week for. 6 months were: rats and rabbits, 1076 mg/m3; guinea pigs,
538 mg/m ; monkeys, 2052 mg/m3. in another study, rats exposed to
3800 mg TCE/m , 8 hours/day, five days/week for 6 weeks exhibited no
significant toxicity or evidence.of histopathological changes. Rats
exposed continuously to 188 mg/m for 90 days also exhibited no visible
signs of toxicity (Prendergest et al. 1967).
Unlike other chlorinated hydrocarbons, evidence of hepatoxic effects
of TCE is largely inconclusive. Early experiments with dogs exposed to
either 4035 mg TCE/m for 8 hours/day, 6 days/week for 3 weeks or
3066 mg/m for 6 hours/day, 5 days/week for 8 weeks produced degeneration
of parenchymatous liver cells, anemia, weight loss, lethargy and diarrhea
(Seifter 1944).
Later studies using more purified TCE, however, indicate little or .
no hepatoxic effects following TCE exposure. Rats exposed to 116,200 mg/m
TCE for 15-90 hours showed increase intracellular lipid levels but no
liver necrosis (Verne .et ail. 1959). Kylin £t_ al. (1963) found no
evidence of histological damage in the liver of rats following a single
4-hour exposure to 17,210 mg/m3.
In man, transient increases in serum transaminases (which indicates
damage to liver parenchyma)have been observed, however, these increases
usually disappear after exposure is terminated (MRI 1979).
5.1.4 Overview and Summary
5.1.4.1 Ambient Water Quality Criterion - Human Health
The U.S. Environmental Protection Agency (1980a) has established
a zero ambient water concentration for the maximum protection of human
health from potential carcinogenic effects of exposure to trichloroethylene
through ingestion of water and contaminated aquatic organisms. The water
quality criterion is based on the induction of hepatocellular carcinoma
in male B6C3F1 mice given a time-weighted average dose of 1169 mg/kg/day
for 78 weeks. The concentration of trichloroethylene in water calculated
(via a linear^.non-threshold model) to keep any additional lifetime cancer
risk below 10 is 27-28 yg/1 (USEPA 1980a, USEPA 1980c).
5.1.4.2 Trichloroethylene Relation to Human Risk
The potential carcinogenic effect of TCE is controversial. Technical
TCE (1170 mg/kg by gavage) was carcinogenic in B6C3F1 mice, inducing a
5-11
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52% incidence of hepatocellular carcinoma in male mice compared with a
5% incidence in male control mice. No tumors were seen in liver, lung,
or stomach of Ha:ICR Swiss mice intubated with a considerably lower
dose (0.5 mg purified TCE/mouse/week) for a lifetime nor in mice fed
500 mg purified TCE/kg 5 times per week for 52 weeks. Repeated dermal
application of TCE also produced no significant incidence of skin tumors
in Ha:ICR mice and initiation-promotion studies were also negative. No
carcinogenic activity was found in Sprague-Dawley rats fed 240 mg purified
TCE for 52 weeks, then held up to 140 weeks; nor in Osborne-Mendel rats
given technical TCE by gavage; however, high mortality reduced the ability to
detect a carcinogenic response in the latter study. No carcinogenic
effects were observed in Han:Wist rats, Syrian hamsters, or male Han:NMRI
mice exposed to 2690 mg purified TCE/kg by inhalation for 18 months,
although female mice exhibited an elevated incidence of malignant
lymphoma. The significance of this finding, however, is questionable
in view of the 30% incidence of lymphoma in controls. The malignant
lymphomas in the exposed population may be related to an immunosuppressive
effect caused by TCE.
Carcinogenic effects in B6C3F1 mice have been questioned because
of epoxide stabilizers present in the TCE test sample and the high
dosage levels employed. Metabolic overload is another unresolved
issue. Limited data on epoxide stabilizers suggest that they are
inactivated at the acidic pH in the stomach; therefore, it is unlikely
that epoxide stabilizers produced the clear increase in hepatic tumors
seen in TCE-fed B6C3F1 mice. In addition, the structural similarity
of TCE to other known carcinogens, the greater in vitro binding of TCE
to tissue macromolecules and DNA in mice compared with rats, and the
lower levels of epoxide hydrase in mice compared with rats and humans
are factors that may have contributed to the NCI findings.
(The GAG estimated the slope of the dose-response curve to be 1.26 x 10~2
(mg/kg/day)'1. This value is based on a multi-stage extrapolation model
and the observed incidence of hepatocellular carcinoma in male mice in
the NCI study.)
Consumption of 2 liters drinking water/day containing 27-28 ug
TCE/1 has been estimated by the CAG to result in one additional cancer
per 100,000 people exposed. At this time, no epidemiologic evidence sug-
gests that TCE exposure is associated with an increased risk of cancer in
humans. Epidemiologic studies, however, have only recently been initiated.
Positive mutagenic results have been noted in a mammalian cell
transformation assay and weak responses in bacterial and yeast test
systems. However, this occurred only if microsomal activation was
provided. Negative results, however, were found in a dominant lethal
assay with rats exposed to 1614 mg TCE/m for 9 months; and inhalation
exposure of mice (1614 mg/nr) and rats (9684 mg/nr) during gestation
resulted in no indication of fetotoxic or teratogenic effects.
5-12
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ICE is readily absorbed by ingestion or inhalation and is oxidized to
chloral hydrate via an epoxide intermediate. Chloral hydrate is then
either oxidized to trichloroacetic acid or reduced to trichloroethanol
and eliminated in urine. A major toxic effect of TCE, depression of
the central nervous system, is believed to be associated with the
formation of chloral hydrate. The effects are reversible when removed
from the source. Cardiac arrythmias have been noted with acute exposures
to TCE; however, little liver toxicity has been observed in humans. The
lowest oral lethal dose reported for humans is 50 mg TCE/kg bw. Intolerance
to alcohol is a major interaction of TCE-ethanol exposure and appears
related to a competitive inhibition between TCE and ethanol for microsomal
mixed function oxidases, resulting in depression of TCE metabolism and
its subsequent build up in the blood.
5.1.5 Estimation of Human Dose-Response Relationships for Cancer
5.1.5.1 Introduction
The potential carcinogenic effects of TCE upon humans can be
quantitatively estimated through extrapolation of j.n vivo laboratory
results. The available data concerning mammalian effects are summarized
above. We have selected for extrapolation purposes the data which
demonstrated increased hepatocellular carcinomas in mice. These data
are listed in Table 5- 1 . It must be noted that Interpretation of these
results for human risk assessment is subject to a number of important
qualifications and assumptions:
• Though positive carcinogenic findings exist, there have also
been negative findings in tests with several species. In
view of possible species differences in susceptibility,
pharmaco-kinetics, and repair mechanisms, the carcinogenicity
of TCE to humans is far from certain.
• Assuming that the positive findings indeed provide a basis
for extrapolation to humans, the estimation of equivalent
human doses involves considerable uncertainty. Scaling
factors may be based on a number of variables, including
relative body weights, body surface areas, and lifespans.
• The large difference between the typically high experimental
doses and the actual exposure levels introduce 'uncertainty
into the extrapolation from animals to humans. Due to
inadequate understanding of the mechanisms of carcinogenesis,
there is no scientific basis for selecting among several
alternate dose-response models, which yield different
results.
5-13
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TABLE 5- 1 INCIDENCE OF HEPATOCELLULAR
CARCINOMA IN MICE (NCI 1976)
SPECIES
Male Mice
Female Mice
TCE
DOSAGE
(mg/kg)
2339
1169
0
1739
869
0
HUMAN
EQUIVALENT
(mg/day)
7017
3507
0
5217
2607
0
RESPONSE
31/48 (65%)
26/50 (52%)
1/20 ( 5%)
11/47 (23%)
4/50 ( 8%)
0/20
EXCESS RESPONSE
OVER CONTROLS
60%
47%
-
23%
8%
_
(a)
5 times/week orally for 78 weeks
5-14
-------
5.1.5.2 Calculation of Human Equivalent Doses
The first step in extrapolating the carcinogenic effects of TCE
to humans was to calculate the equivalent human dose rate corresponding
to the experimental treatment. We have followed the approach recommended
by the EPA (Federal Register 1979), which normalizes the dose rate
according to body surface area. This approach is conservative, in
that it results in a lower equivalent human dose than would be obtained
from simple multiplication of animal dose rate (mg/kg/day) by human
body weight. Whether surface area or body weight is a more appropriate
normalization factor is still open to debate. The former method yields
a dose rate about 14 times lower for mice. Thus, the choice of method
introduces an uncertainty of roughly an order of magnitude into the
risk estimates.
The actual calculation of equivalent human dose was performed as follows,
assuming an average human weight of 70 kg:
Human dose • 70 kg x animal dose /animal weight | I5\ x /duration of exposure \
(mg/day) (mg/kg/day) Vhuman weight / \7/ I animal lifespan /
The correction factor for body surface area is the cube root of the ratio
of animal to human weight, as shown in the Federal Register (1979).
A correction factor of 5/7 was also included since the animals were
treated only on five days per week. As a result, we conclude that one
mg/kg/day to a mouse is equivalent to about 3 mg/day human intake.
5.1.5.3 Estimation of Human Risk Relationships
In order to indicate a range of possible carcinogenic risk to
humans, three dose/response extrapolation models were applied to the
human equivalent dose/response data. Results are shown in Table 5-2.
These models were the "one-hit" model with a linear "hazard rate," (this
model is also used by CAG) the log-probit model, and the one-hit model
with a quadratic hazard rate (also known as a "multi-stage model). All
of these models are well described in the literature, and theoretical dis-
cussions may be found in Arthur D. Little (1980) and the Federal Register (1979)
The one-hit models assume that the probability F(x) of carcinogenic
response to dose x is described by
«/ \ -i ~h(x)
P(x) = 1 - e ,
where h(x) is the hazard rate function.
5-15
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TABLE 5-2 ESTIMATED LIFETIME CARCINOGENIC RISK
PER CAPITA DUE TO TCE INCESTION(a)
EXPOSURE LEVEL OR DOSE (ing/day)
0.01
0.1
10
100
Linear Model
CAC Model
-------
The log-probit model assumes that human susceptibility varies
log-normally with dose.
Due to differing assumptions between the two dose-response models,
they usually give widely differing results when effects data are
extrapolated from high laboratory doses to the low doses typical of
environmental exposure.
The one-hit model with linear hazard rate function (often simply
referred to as the "linear one-hit model" since its behavior at low
doses is linear) is the model used by the Carcinogen Assessment Group
(GAG). According to this model, the probability F (x) of carcinogenic
response in test subjects treated with dose x is
where B and C are constants determined from the data. First solving
for C, with x •• 0, and rewriting, it is found that
P (x) - 1 - [1 - P (0)] e'Bx,
i
where P (0) is the probability of response at dose zero, i.e., the
proportional response of the control group. Thus,
B • -
x *" \1 - Pt(x) / .
The probability P (x) of carcinogenic response attributable to dose x
is then a
Pt(x) " Pt(0) . -Bx (see footnote)
1 - Pt(0) - i - «
It was found that the male mouse data indicated a higher rate of
excess cancer,incidence, yielding a conservative estimate of
B a 1.8 x 10~ , roughly. The inferred human per capita risk at low
dose levels may then be found simply by multiplying the coefficient B
by the dose in mg/day. (Note that dose can also be normalized by
body weight and can be expressed in mg/kg/day.)
P (x) a Bx
Note the distinction between P (x), the probability of response
attributable to the carcinogen^ and P (x), the probability of response
attributable to both the carcinogen and background effects. The
probability P_(x) is referred to as the "excess cancer incidence."
5-17
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The estimated incidence of cancer in a given population may then
be found by multiplying the probability of response times the size of
the population.
For the log-probit extrapolation, we solved for the "probit"
intercept A in the following equation:
P(x) - * (A + loglf) (x))
where * is the cumulative normal distribution function.
This equation makes the usual assumption that the log-probit dose-
response curve has unit slope with respect to the log-dose. Again, the
more conservative results for male mice were utilized to estimate A,
though in this case the difference was less important. Using tables
of the standard normal distribution we find that A is approximately
equal to -3.6. This value may then be used to find the probability
of a response at various dose levels from the above equation.
The multi-stage model, using a quadratic hazard
rate functioc,
2
h(x) = ax + bx + c,
was fit to both the male and female mouse data combined. To estimate
the parameters a, b, and c we used a maximum likelihood method, aided
by a computer program which performed a heuristic search for the best
fit. It was found that the parameter b dominated for small values of
the dose x, so that the dose-response function was essentially linear _
in the low-dose region. The value of b was found to be 6.5 x 10~5(mg/day)
Table 5-2 summarizes for a range of exposure levels the risk estimates
obtained from these three models. The estimated lifetime per capita
risk for the exposed population is shown for daily exposures ranging
from 1 ug/day to 100 mg/day.
The gap between the estimates is large in the low-dose region;
thus, there is a substantial range of uncertainty concerning the actual
carcinogenic effects of TCE. However, present scientific methods do
not permit a more accurate or definitive assessment of human risk.
5.1.5.4 Other Considerations
Several approaches were taken to the estimation of human health
risks from exposures to trichloroethylene by the Carcinogen Assessment
Group (GAG 1980). These estimates were mainly directed toward the
carcinogenic response to air pollution. They first used the data of
Henschler ££ al. (1980), who observed the following incidence of
malignant lymphomas in female mice under inhalation exposure: 9/29
(control); 17/30 (100 ppm); 18/28 (500 ppm). Formation of hepatocellular
5-18
-------
carcinomas was not observed. We did not use these data in our risk
extrapolation due to the high control incidence, the dubious pathological
interpretation, and the negative results obtained with male mice, as well
as rats and hamsters. In any case, the CAG's estimated risk of lymphoraas
did not differ greatly from the estimates based on the NCI study
(Table 5-1), which offers a more solid basis for extrapolation.
The Carcinogen Assessment Group analysis also dealt with the
results of the NCI study, where hepatocellular carcinomas were observed
in male mice due to exposure to trichloroethylene by gavage. Although
the Carcinogen Assessment Group stated that it used a multistage model,
it, in fact, used a one-hit model by setting the second-order coefficient
equal to zero. The potency or dose-response slope for humans derived _.
from the one-hit model applied to this set of experiments was 1.26 x 10"
per mg/kg/day (CAG 1980). This is equivalent to a risk of about 1.8 x 10~A
per mg/day, which is exactly the dose-response slope that was derived above.
5.2 HUMAN EXPOSURE
5.2.1 Introduction
For estimating human exposure to TCE, certain populations were
assumed to be exposed to representative concentrations in the environ-
ment, foodstuffs, and drinking water. These concentrations were selected
from monitoring data and estimates determined in the fate section. .
Estimates of exposure durations and maximum intake from exposure were
used as an upper bound for the risk estimates in Chapter 7. These
exposures are not definitive, but rather indicate the range of potential
exposures.
The TCE environmental fate analysis has shown that measurable
levels of TCE may occur in all environmental media — air, water,
soil, and sediment. Monitoring data support this analysis, demonstrating a
wide range of TCE levels in the natural environment and in foodstuffs.
Therefore, all three exposure routes—inhalation, ingestion, and dermal
contact — were considered.
Certain data are required in order to identify exposed populations
and estimate the duration of exposure. Such data include the sources
and amounts of TCE released to each medium, the persistence and con-
centration of the chemical, and the human activities occurring in
proximity to each source type. Residence (urban, rural, or remote),
occupation, and diet are the predominant factors influencing TCE
exposure. Some exposure has occurred in the past during certain
medical operations; however, it is reported that TCE is no longer used
in these procedures. Therefore this exposure route will not be
discussed.
Occupational exposure is the primary concern since TCE is used
almost exclusively (90% of annual production) in the work environment.
Other federal agencies have investigated these risks (Page and Arthur
1978, NIOSH 1978); therefore, they are not reviewed in detail in this
report. For comparative purposes, however, the exposed population
directly handling TCE will be reviewed.
5-19
-------
In addition to the monitoring data and fate analysis, the work of
Anderson e£ al. (1980) dealing with atmospheric exposure routes will be
discussed in this section.
5.2.2 Exposure Scenarios
5.2.2.1 Populations Exposed Through Inhalation
The three plants that manufacture trichloroethylene and the 57,OOP
industrial and commercial degreasers identified by Anderson e_t al. (1980)
account for most of the TCE release to air.
Populations exposed to TCE by inhalation are distinguished according
to their general proximity to release of TCE into three groups: urban,
rural, and remote. These groups have been arbitrarily assigned to
coincide with selected ranges and levels of ambient atmospheric concen-
trations shown in Table 5-3. Specific subgroups of the three general
groups include populations who live and/or work near user sites or near
manufacturing sites.
Populations working in the vicinity of a source may be exposed 40
hours/week, while residents in the area of a source may only be exposed
during the time a plume from the source is in the atmosphere around
them. In this case, emissions may be reduced or eliminated at the
end of the working day, and night-time exposure would drop to the local
background level. Weather conditions will also alter the dispersion of
the emissions, so that exposure may vary in any given location, even
if the emission rate is absolutely constant over time. The duration of
exposure to concentrations in the area of a source has been assumed to
be 40 hrs/wk, corresponding with the length of the work week. An
analysis of site-specific data would be required to refine this duration
estimate.
Anderson &^ al. (1980) performed an exposure analysis based on plume
dispersion and population distribution by Standard Metropolitan Statistical
Areas (SMSA's). These authors estimate that about 4000 people in the US
would be exposed to TCE levels >0.1 ug/m • This exposure assessment is
not based on the Anderson e£ al.. analysis for the following reasons:
atmospheric TCE concentrations in remote areas have been found to be
approximately 0.03 yg/m and in many other places, particularly urban
areas, concentrations >0.1 ug/nr have been detected. The Anderson e_t al.
(1980) analysis also indicates that at 93% or more of the 57,000 degreasing
sites, populations outside the plants will be exposed to no more than
three times the ambient background levels. Higher concentrations have
been measured in cities in which a substantial portion of the population
may be exposed. Monitoring surveys have recorded up to 215 ug TCE/m^
near user sites (see Chapter 4).
5.2.2.2 Populations Exposed through Ingestion of Contaminated Drinking
Water and Foodstuffs
Human exposure to TCE may result from ingestion of contaminated
drinking water, either surface or well water. The monitoring data
5-20
-------
TABLE 5-3 ESTIMATED NONOCCUPATIONAL EXPOSURE TO TRICIII.OROETim.ENE VIA INHALATION
Ui
K)
fa)
Location
Near Manufacturing Site
Urban - Day (near manufacturer)
- Night (Bayonne, NJ)
Rural - Day (near manufacturer)
- Night (Talledega Nat. Forest)
Near Degreaslng Sites
Urban - Day (Aircraft Factory) .
- Night (Bayonne, N.I)
Rural - Day (Aircraft Factory)
- Night (Talledega Nat. Forest)
Low Ambient - Rural (Talledega Nat. Forest) or
Urban (East Const)
Maximum Observed
Concentration
(|ig/m )
or
1440
47
1440
3
235
47
235
3
3
Weekday
Durat ion
of
Exposure* '
(lirs/day)
8
16
8
J6
8
16
R
16
24
Estimated Total
Intake-'0
(mg/day)
" I
0.6 J
" (
0.04 \
,., j
0.6 \
,., j
0.04 )
0.06
14.6
14.04
2.9
2.34
Remote Locations (Ambient Background)
0.03
24
0.0006
00,.
Concentration estimates arc taken from Table 4-5.
(10
Weekend exposures wUl be 24 hr/day nl nlghl 11« .eve.s. Henre. these values provide „„ upperho.nul
esllmnte daily on exposure levels. ' ' IIIM1IUI
Vnliit-H arc rounded, llascd on iv.splr.-it Ion of 1.2 m /|,r (awak..-), 0.4 n/Vhr (.sli-rplu)'), .-iliout 20 inJ/day
(ICUI' 1975).
-------
indicate that some drinking water supplies, primarily wells, have been
contaminated, some to high levels. Because the populations exposed to
these sources are likely to be isolated and distinct with regard to the
whole population, it is difficult to estimate a representative TCE
exposure or the sizes of the affected populations. Because of the high
degree of variability in the actual levels of TCE in drinking water (U.S.
EPA 1980b), an average level of 2 ug TCE/1 has been used to estimate
the average exposure from all drinking water sources. This level is
considered conservative in that it overstates generally observed con-
centrations, if detected at all, in the majority of surface and ground-
water supplies sampled (see Table 4-6). It may, however, underestimate
exposure for isolated cases in which high concentrations of TCE were
detected. An exposure concentration of 3,000 ug/1 (SLCWS 1975) was
selected as the maximum potential exposure from drinking water. Although
higher concentrations have been found, it was assumed that consumption
of such water would be deterred by the characteristic odor of TCE.
Foodstuffs may be contaminated with TCE and human exposure may
result from ingestion. Processing (i.e. caffeine and flavor extraction
from coffee and spices) has been implicated in food contamination in
the past, although the use of TCE in these applications has been
generally discontinued. McConnell ejc al. (1975) have reported TCE
concentrations in foods in the U.K. Although the relevancy of these
concentrations to foods in general is unknown, in the absence of other
information, it is assumed that they represent potential exposure levels.
Information on food quantities consumed was taken from ICRP (1975).
5.2.2.3 Populations Exposed through Dermal Contact
Dermal exposure may occur through contact with washwater and during
sports activities in freshwater. The data on the rate of absorption by
the skin (See Section 5) show that dermal absorption is approximately
one-third that noted for inhalation exposure (Sato and Nakajima 1978).
Exposure durations are most likely very short. The potential environ-
mental exposures via this route are assumed to be low relative to other
routes. Therefore, no estimates were made concerning this route.
5.2.3 Exposure Estimates
5.2.3.1 Air
Estimates of exposure durations for various situations and typical
ambient concentrations for each exposure group are presented in Table 5-3.
The product of the TCE concentration and duration of 'exposure for
each specific human activity and appropriate respiratory rates were used
to estimate total daily exposures (See Table 5-3)• Exposures were
calculated using the average active adult breathing rate of 1.2 m /hour
(16 hours), which falls to 0.4 m3/hour during sleep (8 hours) (ICRP 1975).
The numbers presented in Table 5-3 represent possible intakes of TCE.
5-22
-------
Occupational exposure estimates are shown in Table 5-4. The assump-
tions presented above also apply here. Concentrations were taken from
various sources and compiled by Page and Arthur (1978).
The highest non-occupational inhalation exposures are near TCE manu-
facturing sites. Only three plants in the United States manufacture TCE.
The exposed population is estimated to number fewer than 100,000 people
based on census data on the populations outside the central cities of
Lake Charles and Baton Rouge, and an additional 7,000 for Freeport, a
highly industrialized area. Some 57,000 degreasing facilities are
scattered throughout the United States and fugitive emissions from .
these facilities may affect some of the 120.7 million people living in
urban areas (U.S. Bureau of Census 1979).
The exposure calculations in Table 5-3 and 5-4 show that non-
occupational intakes may range from <0.01 mg/day to ^15 mg/day, while
those for occupational exposures are between 0.05 g/day and 5.8 g/day.
The estimated non-occupational exposures that may occur in proximity
to a source were from three to several hundred thousand times less than
occupational exposures, while exposures in remote areas are up to nine
million times less.
5.2.3.2 Water
Water consumption of 2 liters/day containing TCE at an average con-
centration of 2 ug/1 or a maximum potential concentration of 3,000 yg/1
would result in intakes of 0.004 mg and 6 mg TCE per day, respectively
(Table 5-5). Therefore, contaminated water may contribute to ingestion
of a substantial amount of TCE relative to inhalation if the water is
highly, contaminated, i.e., >300 ug/1 (an uncommon event)(see Table 5-5
and Chapter 4). Generally observed levels result in intakes <0.1 mg/day.
The size of the population exposed via this route is unknown.
5.2.3.3 Food
Ingestion of food contaminated at the assumed levels results in
an estimated TCE intake of much less than 1 mg/day, a level similar
to that estimated for drinking water (Table 5-5)• As mentioned pre-
viously, this estimate may not represent actual situations because
concentrations vary considerably and it is unknown how widespread
food contamination may be.
5.2.4 Summary
The results of the exposure estimates are summarized in Table 5-6.
Inhalation is the dominant exposure route. Depending on location and
exposure duration, ingestion may be relatively more significant to total
exposure. For these reasons, a 0.0006mg/day (ambient atmospheric back-
ground inhalation exposure) minimum to approximately 15 mg/day (10 mg/day
inhalation plus 5 mg/day ingestion) maximum potential exposure range is
estimated.
5-23
-------
TABLE 5-4 ESTIMATED OCCUPATIONAL EXPOSURE TO
TRICHLOROETHYLENE VIA INHALATION
Facility
or
Operation
Exposure
(a)
Exposure
Duration
Concentration
(mg/m') (hours/day)
Daily
Exposure
(mg/day)
.(b)
DECREASING TANK OPERATION
minimum 5.4
maximum 600
median 270
8
8
8
52
5800
2600
TANK CLEANING
minimum
maximum
1240
6010
0 5(d)
Ui3/j\
0.5(d)
74rf->
3600(e)
ELECTRICAL COMPANY
minimum
maximum
20
215
EXPOSURE AT TLV (538 mg/m3) 540
8
8
200
2100
5200
(a),
(b)
(c),
lata from Page and Arthur (1978).
I
Estimates rounded. Respiration of 1.2 m-Vhr, 100% retention assumed.
'Three surveys3of degreasers indicated that air concentrations less
than 270 mg/m occurred at 58%. 48% and 60% of the tanks sampled,
while 81%, 93%, and 86% were less than 540 mg/m .
(d)
Arthur D. Little, Inc. estimates.
Tank cleaning will not necessarily occur weekly, but only when
the grease sludge buildup is excessive, which will be dependent
upon the size of the overall operation.
5-24
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TABLE 5-5 ESTIMATED TRICHLOROETHYLENE EXPOSURE
BY DIGESTION: AMOUNTS, CONCENTRATIONS,
AND EXPOSURE BY SOURCE
Source
Amount
Peg/day)
Concentration
(yg/kg)
Total TCE Exposure
(ing/day)
DRINKING WATER
Maximum Level
(a)
Typical Level
(b)
2
2
3000
2
6
0.004
Water Quality
Criterion
0.004
FOODSTUFF
Milk
Cheese
Eggs
Meats and Products
Oils and Fats
Potatoes
Fruits
Grains
0.5
0.016
0.02
0.2
0.05
0.10
0.2
0.2
0.3
3
0.6
16
8
3
4.5
7
TOTAL FOOD
1.5 x 10
5 x 10'5
1.2 x 10
3.2 x 10
4 x 10~4
3 x 10~4
9 x 10"4
1.4 x 10
-4
-3
-3
6.4 x 10
-3
(a)
Although higher levels have been observed, it is assumed that consumption
of water containing more than 3,000 ug/1 would be deterred by the character-
istic odor of TCE.
Because of the high degree of variability in the actual levels of TCE in
drinking water, an average level of 2 yg TCE/I was used to estimate the
typical exposure from all drinking water sources. This level is considered
conservative in that it overstates generally observed concentrations, if
detected at all, in the majority of surface and groundwater supplies (see
Table 4-6).
(c)Data from ICRP (1975).
5-25
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TABLE 5-6 SUMMARY OF ESTIMATED EXPOSURE TO TRICHLOROETHYLENE*
Estimated Total
Route Exposure (ing/day)
Inhalation: Non-Occupational
Activities near manufacturing sites 14
Activities near degreasing sitesb 2.6
Night-time background: urbanc 1.0
Sight-time background: rural<* 0.07
Remote Areas 0.0006
Inhalation: Occupational 52-5800
Ingestion:
Food 0.006
Water 0-6
MOTE: aAll populations may be exposed but not all will be exposed
continuously. These estimates are, therefore, conservative
and would overstate the possible exposure for the population
in general.
^Average of rural and urban exposures, Table 5-3.
cNighttime ambient concentration around Bayonne, N. J.,
(47 ug/m3) taken as a representative ambient urban con-
centration.
^Nighttime ambient concentration at Talladega National
Forest (3 ug/m3) taken as representative of rural con-
centrations .
5-26
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chloro- or tetrachloro-derivatives of ethane and ethylene. Brit J. Ind.
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-------
Infante, P. F.; Marlov, P. B. Evidence for the carcinogenicity of selected
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International Agency for Research on Cancer (IARC). Monographs on the
evaluation of the carcinogenic risk of chemicals to man: Trichloroeethylene.
11:263-71; 1976.
Ismailov, A. A.; Ryskal, G. V. Mutagenic effect of trichloroethylene in
offspring of the fly Drosophila melanogaster. Ser. Biol Nauk 6(1):10;
1976 (As cited by Chemical Abstracts 87(17):128-386u
Klaassen, C. D.; Plaa, G. L. Relative effects of various chlorinated
hydrocarbons on liver and kidney function in mice. Toxicol. Appl.
Pharmacol. 9:139-151; 1966. (As cited by IARC 1976).
Klaassen, C. D; Plaa, G. L. Relative effects of various chlorinated
hydrocarbons on liver and kidney function in dogs. Toxicol. Appl.
Pharmacol. 10:119-131; 1967. (As cited by IARC 1976).
Kylin, B.; Reichard, H.; Sumegi, I.; Yllner, S. Hepatotoxicity of inhaled
trichloroethylene, tetrachloroethylene, and chloroform. Single exposure.
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Leibman, K. C. Metabolism of trichloroethylene in liver microsomes.
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Lloyd, J. W.; Moore, R. M., Jr.; Breslin, P. Background information on
trichloroethylene J. Occup. Med. 17:603-5; 1975.
Maltoni, C. Results of long-term carcinogenicity bioassays of trichloro-
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McConnell, G.; Ferguson, D. M.; Pearson, C.R. Chlorinated hydrocarbons
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5-29
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Midwest Research Institute (MRI). An assessment of the need for limitations
on trichloroethylene, methyl chloroform and perchloroethylene. Draft
Final Report. Washington, D. C.: Office of Toxic Substances, U. S.
Environmental Protection Agency; 1979. p. 5-1 to 5-132.
Monster, A. C.; Boersma, G.; and Duba, W. C. Pharmacokinetics of trichloro-
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Int. Arch. Occup. Environ. Hlth. 38(2):87-102; 1976.
Muller, G.; Spassovski, M.; Henschler, D. Metabolism of trichloroethylene
in man. II. Pharmacokinetics of metabolites. Arch. Toxicol. 32:283-295;
1974. (As cited by Waters et al. 1976).
Muller, G.; Spassovski, M.; Henschler, D. Metabolism of trichloroethylene
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5-30
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14
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5-31
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6.0 EFFECTS AND EXPOSURE—BIOTA
6.1 EFFECTS ON BIOTA
6.1.1 Introduction
This section presents a discussion of the TCE levels that cause
mortality or disrupt physiologic functions and processes in aquatic
organisms. The effects of TCE in various organisms have been determined
by laboratory studies under both static and flowthrough experimental
conditions. Often, bioassay data from these two methods are inconsistent
for the same species. The static bioassay test for aquatic organisms
measures one initial concentration of a chemical to determine toxicity
without compensation for loss or lack of availability. In flowthrough
bioassay tests, a fresh solution containing the test substance is con-
tinuously or periodically supplied to the organisms throughout the test
period. A problem with the static bioassay is that the test concentra-
tions may change rapidly as a result of volatilization or degradation of
certain test compounds (MRI 1979). In both kinds of bioassays, the
concentrations are often determined nominally (i.e. by diluting a measured
amount of the substance) rather than by direct periodic measurement
during the bioassay. Nominal determination of concentrations does not
account for toxicant evaporation, absorption onto particles or walls of
a test tank, or absorption by test organisms; thus, lethal and sublethal
levels may be overestimated. TCE is a highly volatile compound, with a
half-life in water of only a few hours to a few days depending on the
water body. (See Chapter 4)
TCE has been shown under laboratory conditions to be lethal to fish
and other aquatic organisms and to affect such functions as equilibrium,
respiration, and reproduction (Pearson and McConnell 1975, MRI 1979).
Sensitivity to TCE differs among species and various life stages of single
species. It is therefore difficult to define precise toxicity values
for this compound.
6.1.2 Freshwater Organisms
6.1.2.1 Acute Effects
Acute toxicity is defined as toxicant-induced mortality over a short
period, generally within 96 hours of exposure. Although aquatic organisms
in natural waterways are more likely to be exposed to lower concentrations,
which may result in chronic or sublethal effects, industrial discharges
and accidental spills can temporarily result in levels high enough to cause
mortality.
The acute effects of TCE to freshwater biota have been studied for
three species, thus, information is limited. Fathead minnows, bluegill,
and the cladoceran Daohnla magna. an invertebrate, were the organisms
tested. The doses lethal to one-half the test population (LCso's) for
these organisms are presented in Table 6-1. Both static and flowthrough
tests were conducted for the finfish species; of these species, the
bluegill was the most sensitive. The LC50 for Daohnia is 85 mg/1, about
6-1
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TABLE 6-1. ACUTE TOXICITY OF TRICHLOROETHYLENE
FOR FRESHWATER FISH AND INVERTEBRATES
Organism
Freshwater Fish:
Fathead minnow
(Pimephales promelas)
Fathead minnow
(Pimephales promelas)
Blueglll
(Lepomis macrochirus)
Bioassay Test , Time
oioassay lesc , lime ""50
Method* Cone. (hrs) (mg/1) Reference
FT
M 96 40.7 Alexander et a!.,
(1978)
U 96 66.8 Alexander et. al.
(1978)
U 96 44.7 U.S. EPA (1978)
Freshwater
Invertebrates:
Cladoceran
(Daphnia magna)
48
85.2 U.S. EPA (1978)
a S - static, FT - flow-through
b U - unmeasured, M - measured
Note: The lowest value from a flowthrough test with measured concentrations
40.7 mg/1.
6-2
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2.5 times higher than the "LC$Q for fish. Bioconcentration by bluegill
was studied by the U.S. EPA (1978) using radiolabeled TCE. After 14 days,
the bioconcentration factor was 17.
6.1.2.2 Chronic Effects
Sub lethal or chronic effects of a substance, indicated by the
value (concentration causing the effect in 50% of test organisms) , are
generally determined by observation of effects such as loss of equilibrium,
melanization, narcosis, swollen or hemorrhaging gills, and changes in
reproductive habits of capabilities (MRI 1979). Data on chronic toxicity
are very limited; only one test has been conducted on TCE and freshwater
organisms. That study with Daphnia magna provided incomplete results
because no adverse effects were detected at the maximum test concentration
of 10 mg/1. Since the 48-hour ECso value for Daphnia is 85.2 mg/1 and
there was no observed adverse effect during the chronic test at 10 mg/1,
the difference between acute and chronic effects levels for this species
is less than 8.5 times the chronic test level (U.S. EPA 1980).
A comparison of the effective concentration values (levels producing
loss of equilibrium) and lethal concentrations of TCE in flowthrough
tests on fathead minnows (Pimeohales promelas) is presented in Table 6-2.
Concentrations producing sub-lethal effects in 50% of the fish (EC-Q)
were 23.0 mg/1 (MRI 1979).
6.1.3 Marine Organisms
6.1.3.1 Acute Effects
Information on acute toxic effects of TCE is limited; however, data
are available concerning finfish, shrimp, polychaetes, barnacle larvae,
and phy top lank ton. Limited toxicity data indicate that marine mammals
take up and accumulate TCE in the low ug/1 range, 2.5-7.8 ug/kg wet weight
(MRI 1979).
Data concerning TCE toxicity for saltwater fish are presented in
Table 6-3. Investigations concerning acute and sublethal toxicity
report median lethal concentration (1X53). Non-lethal effects have also
been noted. Fish appear to be sensitive to low concentrations (mg/1 range).
The LCso (48 hr) value for the barnacle nauplii was 20 mg/1. Another
organism included in the study by Pearson and McConnell (1975) study was
the unicellular algae Phaeodactylum trlcornutum. The EC5Q for this
species was 5 mg/1. Marine algae take up and accumulate TCE in the low
mg/1 range and have an accumulation factor of less than 100 (MRI 1979).
Acute toxicity studies were conducted on the polychaete Ophryotrocha
labronica using a static system. An initial momentary exposure to 400
mg TCE/1 killed all test organisms within 24 hours. Approximately 40% of
the test population was dead within 24 hours in 250 mg/1, however,
the mortality rate decreased after the 24-hour period and was roughly
constant for the remainder of the experiment. In 300 mg/1 75% of the
6-3
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TABLE 6-2. RESULTS OF FLOWTHROUGH STUDIES
OF CHRONIC AND ACUTE TOXICITY
OF TRICHLOROETHYLENE FOR THE
FATHEAD MINNOW
Effective concentration (EC) value ' (mg/1)
Hr
24
48
72
96
Hr
2'4
48
72
96
EC10
15.2
16.9
15.5
13.7
Lethal
LC10
34.7
27.7
20.9
17.4
EC50
23.0
22.7
22.2
21.9
concentration (LC) value
LC50
52.3
. 53.3
39.0
40.7
EC90
36.2
30.6
31.8
34.9
(mg/1)
LC90
79.1
102.6
72.6
95.0
a The effect noted was loss of equilibrium.
b MRI (1979).
c Alexander et al. (1975).
6-4
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TABLE 6-3. TOXICITY OF TRICHLOROETHYLENE FOR SALTWATER FISH
Organism
Test
Condition
Concen-
Toxic tration
Effect (mg/1)
Reference
Dab
(limnada limnada)
Flowthrough LC5Q (96/hr) 16
McConnell et al.
(1975)
Pinpearch
(Lagodon, rhomebodius)
Grass Shrimp
Sheepshead minnow
Static LC5Q (24/hr) 75-100 Garrett (1957)
96 hr \ erratic swimming,
( uncontrolled move-
96 hr I ment.loss of
equilibrium
2.0
Borthwick 1977
6-5
-------
polychaetes were dead in 3 days following a shock tesc, whereas all
polychaeces survived, wich somewhat reduced activity, if exposure to 300
tng/1 was made gradually. In 600 mg/1, the entire test population died
within 96 hours; and in 400 mg/1, 25% of the polychaetes were alive after
120 hours and survived through the eighth day of experimentation (Rosenberg
e£ al. 1975). The decrease in the mortality rate over time could result
from volatilization and consequent decreased concentration of TCE
(Rosenberg e_£ al. 1975).
Grass shrimp and the sheepshead minnow demonstrated erratic swimming,
uncontrolled movement, and loss of equilibrium after several minutes of
exposure to 2 mg/1 and 20 mg/1 of TCE, respectively. (Borthwick 1977)
6.1.3.2 Chronic Effects
When reproductive female polychaetes were exposed to 200 mg/1 THE,
fewer eggs and egg masses than normal were found. Far lower TCE
concentrations affected the reproductivity of Ophryotrocha than those
concentrations causing acute toxic effects. Eggs hatching decreased in
150-200 mg TCE/1; however, the LCso value was 400 mg/1 (Rosenberg et al.
1975).
6.1.4 Other Studies
Biggs e£ al. (1979) conducted experiments to determine if TCE had any
effect on phytoplankton. Mixed laboratory cultures of known sensitive
species, the estuarine centric diatom Thalassiosira pseudonana and a resis-
tant green alga Dunaliella tertiolecta, were exposed. TCE concentrations
of 50 ug/1 and.100 ug/1 caused no detectable effects onalgae growth or
size of progeny in both species. The authors predicted that TCE concen-
trations in this range (50-100 ug/1) and lower are unlikely to reduce
algae growth or alter species succession of phytoplankton in natural
systems (Biggs e_t al. 1979).
Limited data suggest that excessively high concentrations of TCE
have a potential for disrupting activated sludge systems. Studies
conducted on sewage treatment facilities in Michigan indicated that TCE
concentrations >500 mg/1 had a significant potential for completely
inhibiting bacterial activity and partially inhibiting the synthesis of
enzymes in these systems. It was concluded that at concentrations up to
300 mg/1, little, if any, effect would occur (MRI 1979). (Section 4.3.4.1
further discusses the waste treatment process.)
6.1.5 Summary
According to the literature, 2 mg/1 was the lowest TCE concentration
reported to affect aquatic organisms in the laboratory. Intoxication
was noted in marine grass shrimp. The marine flatfish Llmnada limnada
was the most sensitive finfish species tested, with an LCso of 16 mg/1.
Barnacle nauplii were also sensitive to TCE concentrations in the low
mg/1 range, with a LC50 of 20 mg/1. The most resistant organism tested
was the polychaete Oohryotracha labronlca. with an LC50 of 400 mg/1.
General concentration ranges can be established for certain effects
observed in the laboratory. These ranges are not rigidly defined, however,
6-6
-------
and may overlap as a result of differences among species, life stages, or
environmental variables. These ranges include:
• <10.0 mg/1 represents the lowest range at which toxic effects
were observed in any aquatic organism; toxic to unicellular
marine algae.
• 10-20 mg/1 represents the toxic concentration to marine
flatfish and barnacle nauplii.
• 20-100 mg/1 represents the acutely toxic range to several
species of freshwater fish (40-70 mg/1), to the saltwater
fish pinpearch (75-100 mg/1), and to Daphnia (85.2 mg/1).
Chronic effects on fathead minnow were observed at 22.0
mg/1.
• 100-500 mg/1 represents the acute and sub-lethal (reproducti-
vity changes) effects to adult polychaetes of the species
Ophryotracha labronica.
• >500 mg/1 represents the significant potential believed to
exist for major effects on waste treatment through inhibition
of bacterial activity.
6.2 BIOLOGICAL FATE AND BIOACCUMULATION
The bioaccumulation of any chemical can be affected by those para-
meters of the soil, water, or air that affect the biological action of
that compound. The behavior of a chemical in water is typically affected
by temperature, oxygen concentration, water hardness, the presence or
absence of other cations, and pH.
Accumulation has been defined as the increase in the level of a
material in the issues of a test organism. Biomagnification is used
herein to refer to increases in concentration up a food chain. (Accumula-
tion aid bioaccumulation are considered to be synonymous terms.) Little
data are available on the variables that influence the bioaccumulation
of TCE specifically.
6.2.1 Aquatic Biota
Aquatic organisms absorb TCE from the water by direct diffusion
across wetted membranes and by absorption into the digestive tract (U.S.
EPA 1977b). Based on a partition coefficient (KQW) of 195 in an octanol/
water system (log p = 2.29), TCE is expected to bioaccumulate slightly
in fatty tissue. The 195 Kow indicates a propensity to transfer from
water to a lipid phase and bioaccumulate. In many cases lipophilicity
is offset by susceptibility to metabolic degradation. Metabolism generally
converts lipophilic compounds to polar metabolites,which are excreted
by the kidneys (Radding"et_ al. 1977). The biological half-life of TCE
in freshwater, fish tissue is reported to be less than one day (U.S. EPA
1979).
6-7
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Aquatic planes absorb ICE directly from water and via root uptake
from sediments.
6.2.1.1 Fish
Pearson and McConnell (1975) reported that the ICE concentrations in
fish flesh from the U.K. range from 0.8 ug/kg to 11 ug/kg,while the
concentration in fish liver ranged from 2 ug/kg to 56 ug/kg on a wet
weight basis. Sampling of aquatic vertebrates from regions in England
having major organochlorine plants showed a maximum of approximately
100-fold bioconcentration between seawater (0.5 ug/1) and the tissues
such as ray liver (56 ug/lg) of animals higher in the food chain.
(Pearson and McConnell 1975, U.S. EPA 1980.)
Dickson and Riley (1976) recorded TCE concentrations in various
organs of five species of marine fish. Their results are in the same
range as those of Pearson and McConnell (1975) if adjustments are made
for the wet weight factors in the latter study. Dickson and Riley
(1976) did not determine a TCE bioconcentration order for the various
organs of each fish species. The highest concentration factor between
the seawater and fish TCE concentrations was 171,which occurred in the
dogfish liver.
Accumulation in marine species from the relatively uncontaminated
Erin Sea show enrichment factors of 2-25 times (dry weight) (Dickson and
Riley 1975).
Limited data are available on biocencentration of TCE in freshwater
species. After a 14-day exposure, a BCF of 17 was obtained for bluegill
exposed to radiolabelled TCE (U.S. EPA 1978).
6.2.1.2 Birds and Mammals
TCE has been observed to accumulate in the eggs and internal organs
of aquatic birds and mammals. Freshwater and saltwater birds accumulated
from 2.4 ug/1 to 33 ug/1 (wet weight) in eggs. A maximum of approximately
a 66-fold increase in concentration was detected between seawater (0.5
Ug/1) and kittiwake eggs (33 ug/kg).
Based on the limited data, aquatic mammals are able to take up and
accumulate TCE in the low ug/1 range. The grey seal had a TCE level of
2.5-7.2 ug/1 in blubber and 3-6.2 ug/1 in liver. (Pearson and McConnell 1975)
6.2.1.3 Invertebrates
Pearson and McConnell (1975) reported TCE levels in invertebrates
ranging from none determined in whelk and ragworm to 16 ug/1, wet
weight basis, in shrimp. Dickson and Riley (1976), however, detected a
TCE level in the whelk (Baccinum undatum) digestive gland of 2 mg/1 on a
dry weight basis. They also found TCE in the Modiolus tnodiolus organs
varying from 33 ug/1 in muscle, and 56 ug/1 in the digestive tissue, to
250 ug/1 in the mantle.
6-8
-------
The Pearson and McConnell (1975) study reported that the average
concentration of TCE in the vaters was 0.5 -g/1. This shows TCE uptake
by marine invertebrates to levels that are roughly 1-50 times greater
than that of the surrounding water. The U.S. EPA (1977) reported that
the bioconcentration factor for TCE in marine invertebrates is roughly
10 to 100 times the level in the seawater.
6.2.1.4 Plants
Only one report was found in the literature (Pearson and McConnell
1975) containing data on the uptake and accumulation of TCE in aquatic
plants. Marine algae containing 16 to 23 ug/1 TCE were found in waters,
with an average TCE level of 0.3 ug/1 and a maximum level of 3.6 ug/1.
This indicates a bioconcentration factor of roughly 4 to 70 times
(U.S. EPA 1977).
6.2.2 Terrestrial Biota
Trichloroethylene .which has been used as a liquid anesthetic,
biotransforms to three products: chloral hydrate, then trichloroacetic
acid and trichloroethanol. In humans, both chloral hydrate and
trichloroethanol possess hypnotic properties. Oxidation of TCE to chloral
hydrate occurs in the microsomal fraction of liver cells, requiring the
presence of MADPH and oxygen. Animal experiments indicate that TCE is a
type I substrate for cytochrome P-450 of the microsomal mixed-function
oxidase system, and that a pretreatment with phenobarbital may enhance
metabolism. Metabolism of chloral hydrate, catalyzed by soluble enzymes,
consists of either oxidation to trichloroacetic acid, or reduction to
trichloroethanol. Trichloroacetic acid is excreted unchanged in the
urine. Irichloroethanol is first conjugated with glucmonic acid, then
excreted in urine (Kelly and Brown 1974).
Generally, animals inhaling TCE rapidly absorb it and readily
metabolize it to chloral hydrate, trichloroethanol, and trichloroacetic
acid; and then excrete it in the urine (U.S. EPA 1977).
6.2.2.1 Vertebrates
Pearson and McConnell (1975) have provided the only information
on TCE levels in non-laboratory species. They reported the accumulation
of 2.6-7.8 ug/kg (wet weight) of TCE in a common shrew (Sorex araneus)
collected in a marsh.
The experimentally determined log P value for TCE is 2.9 (high),
which indicates that the compound may be bioaccumulated. Cohen and
coworkers (1958, cited in Waiter et_ al., 1976) reported detectable levels
of TCE in the blood, brain, adrenals, fat, heart, kidney, liver, lung,
muscle, pancreas, spinal cord, cerebral spinal fluid, spleen, and
thyroid of animals exposed to the compound for periods up to 219 hours.
The relative amounts of TCE in these tissues were not reported in the
secondary source because the data were not adequate for determining the
relationship of the concentration in the tissues. Insufficient information
on the distribution of TCE in different tissues did not allow verification
6-9
-------
of the bioaccumulation potential suggested by the partition coefficient
(U.S. EPA 1977).
Daniel (1963) reported that 72-852 and 10-20% of the total orally
administered dose to rat? could be accounted for in expired air and urine,
respectively, with less than 0.5% appearing in the feces. This indicates
that at least 80% (and probable more) of ingested ICE is systemically
absorbed.
A study of TCE distribution in guinea pigs showed the highest concen-
trations in adrenals and fat and the lowest concentrations in liver and
muscle (Fabre e_t al. 1952).
The biological half-life of TCE and its metabolites has been examined
in humans and experimental animals. In the rat (male, SPE-Wistar II),
concentrations of TCE in expired air were undetectable 8 hours after
inhalation of TCE at concentrations of up to 330 ppm (Kimmerle and Eben
1973). After administration by gavage of 3°ci-labelled TCE to Vistar rats,
72-83% of the radioactivity (presumably primarily TCE) was recovered in the
expired air with a half-life of 5 hours (Daniel 1963). ,
When Nomiyama and Nomiyama (1979) injected rats and rabbits with TCE
intraperitoneai.lv, rats metabolized the substance more quickly. The
biological half-time for urinary excretion of the total trichloro-corapounds
was 0.36 days for rabbits and 0.22 days for rats. The ratio of total
trichloro-compounds in urine to the dose of TCE decreased with increases
in dose level, and remained unchanged at exposure levels over 665 mg/m^
TCE. Although the reasons for these results are not clearly understood,
they may be due to increased respiratory excretion (Nomiyama and Nomiyama
1979).
6.2.2.2 Plants
Alumot and Bielorai (1969) fumigated cereals, for 48 hours, with a
mixture that contained 37% TCE. The amount of TCE absorbed is summarized
below:
Amounts(mg/kg) of TCE Initially
Sorbed by Cereals at Two Temperatures (8C)
Sorghum
Temperature: 17 30 17 30 17 30 17 30
mg/kg TCE: 119 136 105 97 184 187 129 120
In another study, the mean concentrations of TCE observed, after a
2-day extraction of wheat and corn, were 33 mg/kg and 106 mg/kg, respectively
(Panel 1974).
Levels of TCE in fruit and vegetables are shown in Table 4-4. The
levels range from no TCE detected in potatoes from South Wales to 5 us/kg
6-10
Wheat
17
119
30
136
Barley
17
105
30
97
Corn
17
184
30
187
-------
detected In apples. No information was available on the ICE levels
in food of plant origin in the United States (McConneil ejt al. 1975).
6.2.3 Biomaenification in the Food Chain
Pearson and McConnell (1975) determined the level of 'ICE and other
chlorinated hydrocarbons in the tissues of a wide range of organisms.
Species were chosen to represent significant trophic levels in the marine
environment. The maximum overall increase in concentration between seawater
and the tissues of animals at the top of food chains (such as fish liver,
sea bird eggs, and seal blubber) was on the order of 100-fold for TCE
(from 0.5 ug/1 in water to 30 ug/1 in tissues).
The concentrations of TCE in the marine organisms analyzed were in
the range of 1-2 orders of magnitude greater than the level of TCE in the
water. However, Pearson and McConnell (1975) found no evidence of bio-
magnification to any significant extent up aquatic food chains. They
also found that birds and animals representing the higher trophic levels
did not have significantly higher levels of TCE than the fish on which
they fed. The grey seal, representing a higher trophic level, had a TCE
level of 2.5-7.2 ug/1 in blubber and 3-6.2 ug/1 level in liver; thus,
it differs slightly from the lower trophic level invertebrate mussel,
(4-11.9 yg/1) and hermit crab (5-15 ug/1).
Pearson and McConnell (1975) concluded that significant biomagnifi-
cation of TCE does not occur in aquatic food chains. Insufficient data are
available to draw conclusions concerning biomagnification in terrestrial
food chains.
6.2.4 Summary
Accumulation of ICE occurs in both aquatic and terrestrial plants and
animals. The reported residues of TCE detected in aquatic organisms can
be summarized as follows:
. _. Accumulated
Aquatic Biota Concentration Range of TCE (us/kg)
marine fish <0.1-56 (wet weight)
0-479 (dry weight)
birds 2.4-33 (wet weight)
mammals (grey seal) 2.5-7.2 (wet weight)
marine invertebrates 0-16 (wet weight)
2-250 (dry weight)
marine algae 16-23 (wet weight)
plankton 0.05-0.9 (wet weight)
6-li
-------
Terrestrial organisms have been observed to accumulate the following
levels of ICE:
Terrestrial Biota Accumulated Concentration
Ranee of TCE (-_e/kg)
domestic animals 12-22
(beef and pig)
shrew 2.6-7.8 (wet weight)
guinea pigs (laboratory) 5,000-35,000
cereals (laboratory) 33,000-194,000
fruit and vegetables 0-5
The above results show the greater levels that can accumulate under
laboratory conditions.
Animals tend to accumulate more TCE in fatty tissues such as liver.
TCE can be metabolized to biotransformation products that are then excreted
into urine. The biological half-life for TCE in freshwater tissue is
reported to be less than one day; for laboratory animals, it is 5-8 hours.
Although it appears that the range of accumulated TCE is higher in
organisms- farther up the food chain, data are insufficient to conclude
that TCE is biomagnified through the food chain.
6-3 EXPOSURE OF BIOTA TO TRICHLOROETHYLENE
6.3.1 Introduction
Trichloroethylene (TCE) is an organo-chlorine compound that does not
occur naturally in the environment; rather,it arises from anthropic
sources (MRI 1979). Its detection in rivers, municipal water supplies,
groundwater, the ocean, and aquatic organisms indicates that TCE is widely
distributed in the aquatic environment (Pearson and McConnell 1975). TCE
is a highly volatile compound; however, with a half-life in water of
from a few hours to a few days, depending on the waterbody. TCE has been
found in both the influent and effluent water from sewage treatment plants,
resulting in part from chlorination of waste effluents by both industries
and municipalities (Jolley 1975). (See Monitoring Section)
6.3.2 Monitoring Data
Limited field monitoring data were available for TCE and included
small-scale and localized sampling programs in the United States and
England, and ambient and effluent concentrations of TCE from U.S. EPA's
STORET files.
STORET data (Chapter 4.2) reveal that TCE is found in ambient water
samples in the range of 0.14 ug/1-300 ug/1. Effluent concentrations ranged
from 0.01 ug/1 to 1600 ug/1, though most of the 270 samples were less
6-12
-------
Chan 10 ug/1. Other studies showed ICE concentrations in surface waters
up to approximately 200 ug/1, with most levels around 10 ug/1 or less.
Concentrations as high as 5227 ug/1 were found in the vicinities of
manufacturing plants in Louisiana and Texas.
Concentrations of ICE found in seawater in Liverpool Bay, England
averaged 0.3 ug/1. Municipal waters in England, from upland surface
sources, were found to contain up to 6 x 10~9 (by mass) ICE. Rainwater,
also in England, contained a 1.5 x 10~10 (by mass) ICE. Marine sediments
in Liverpool Bay were sampled and found to contain TCE in concentrations
of 9.9 x 10~9 (Pearson and McConnell 1975). Sediment samples taken in
the vicinities of TCE manufacturing and user sites (Battelle Columbus
Laboratories 1977) showed up to 300 UR/1 (dry weight) TCE.
6.3.3 Ingestion
Laboratory and field studies have attempted to determine the extent,
if any, to which aquatic organisms take up and accumulate TCE. Bioaccumu-
lation is considered the increase in the levels of a substance in the tissues
of a test organism, whereas biomagnification refers to the increase in
concentration of a material up the food chain (MRI 1979).
The transfer of compounds from ambient water to the tissues of
organisms occur through two major pathways. The first route is by direct
diffusion across wetted membranes, particularly those involved with
respiration. The second, an indirect pathway is absorption into the
digestive tract, either from particles that have adsorbed the substance,
or directly from the tissues of their food (Pearson and McConnell 1975).
No laboratory studies on toxicity of TCE to aquatic organisms as a result
of ingestion were found. Field and laboratory data on the uptake and
accumulation of TCE by fish are limited. However, these data indicate
that fish do take up TCE from an aqueous environment. Field sampling
showed an average concentration of TCE in fish (high ppb-low ppra range)
to be up to 100 times the concentration found in ambient water. No
evidence was presented in this study supporting accumulation through
food chains (MRI 1979). Laboratory experiments showed that bioaccumula-
tion does occur, but that is is not accompanied by any detected ill effects
(Pearson and McConnell 1975). The lowest concentration observed to be
toxic to aquatic organisms was 16 mg/1 LCen for the marine flatfish
Limnada limnada (McConnell et. al. 1975). 50
6.3.4 Fish Kills
Mo data were available concerning any fish kills related to TCE in
aquatic environments.
6.3.5 Summary
Because of the lack of extensive monitoring data for TCE concentra-
tions in aquatic environments and the high volatility of TCE from water,
it is difficult to propose definitive conclusions regarding exposure levels,
6-13
-------
on a national, regional, or local level. Based on the data available
however, it would appear that where these compounds ara detected, they
are almost always found in low concentrations (<10 vg/1), generally lower
than those levels observed toxic to aquatic biota as discussed previously.
Those few reports of higher concentrations that have occurred near TCE plant
sites were also lower than the concentrations found to be toxic to the
most sensitive aquatic species tested. No data were found on the length
of time these concentrations existed, but given the relatively short half-
life of TCE in water, these concentrations probably did not persist.
Overall, the concentrations to which aquatic biota are exposed are in the
low ug/1 range, but exposures at this level appear to be localized and not
pervasive on a nationwide basis.
-------
REFERENCES
Alexander, H. C.; McCarty, W. M.; Bartlett, E. A. Toxicity of perchloro-
echylene, trichloroechylene, 1,1,1-trichlorcethane, and methylene
chloride co fathead minnows. Bull. Environ. Contain. Toxicol. 20(3):
344-352;1978 (As cited by USEPA 1980).
Alumot, E.; Bielorai, R. Residues of fumigant mixture in cereals fumigated
and aired at two different temperatures. J. Agr. Food Chem. 17: 869-870:
1969.
Battelle Columbus Labs. Determination and evaluation of environmental
levels of methyl chloroform and trichloroethylene. Battelle Columbus
Laboratories 1977. (As cited in MRI 1979).
Biggs, D. C.; Rowland, R. G.; Burster, C. F. Effects of trichloro-
ethylene, hexachlorobenzene and polychlorinated biphenyls on the growth
and cell size of marine phytoplankton. Bull. Environ. Contain. Toxicol.
21:196-201; 1979.
Borthvick, P.W. 1977. Results of toxicity tests with fishes and macro-
invertebrates. Data sheets available from USEPA Environmental Research Lab,
Gulf Breeze, FL. (As cited in USEPA 1980.)
Daniel, J. W. The metabolism of Cl-labelled trichloroethylene and
tetrachloroethylene in the rat. Biochem. Phannacol. 12: 795; 1963.
(As cited by USEPA 1980).
Dickson, A. G.; Riley, J. p. The distribution of short-chain halogenated
aliphatic hydrocarbons in some marine organisms. Marine Pollution
Bulletin. 7 (9): 167-169; 1976.
Fabre, R.; Truhaut, R. Toxicology of trichloroethylene. II. Results
of experimental animal studies. Br. Jour, Ind. Med. 9:36; 1952.
(As cited by USEPA 1980).
Garrett, J. T. Toxicity investigation on aquatic and marine life. Public
Works 88 (12): 95, 1978 (As cited in MKI 1979).
Goldstein, A. e_£ ad. Drug metabolism. In Principles of drug action,
the basis of pharmacology, 2nd ed. John Wiley and Sons, New York,
1974. (As cited in USEPA 1979 p. 18).
Jo1ley, R. L., ed. The environmental impact of water chlorination. Proc.
Conf. on the Environment Impact of Water Chlorination. RNL USERDA,
United States Environmental Protection Agency, 1975.
Kelley, J. M.; Brown, B. R., Blotransformation of trichloroethylene.
Int. Anesthiol. Clin. 12(2): 35-40; 1974 Chem Abs. 81:1142876.
Kimmerle, G.; Eban, A. Metabolism, excretion and toxicology of trichloro-
ethylene after inhalation. 2. Experimental human exposure. Arch.
Toxikol. 30:127; 1973. (As cited in USEPA 1980).
6-15
-------
McConnell, G.; Ferguson, D. M.; Pearson, C. R. Chlorinated hydrocarbons
and the environment. Endeavor 34 (121): 13-18; 1975.
Midwest Research Institute (MRI). An assessment of the need for limita-
tions on trichloroethylene, methyl chloroform, and perchloroethylene.
Draft final report. U.S. Environmental Protection Agency. Office of
Toxic Substances. Washington, B.C.; 1979.
Nomiyama, H.; Nomiyama, K. Host and agent factors modifying metabolism
of trichloroethylene. Industrial Health 17: 21-28; 1979.
Panel on Fumigant residues in grain of the committee for analytical
methods for residues of pesticides and veterinary products in foodstuffs.
The determination of residues of volatile fumigants in grain. Analyst
99: 570-576; 1974.
Pearson, C. R.; McConnell, G. Chlorinated C-± and C- hydrocarbons in the
marine environment. Proc. R. Soc. Lond. B. 189 (1096): 305-332; 1975.
(As cited in MRI 1979 and USEPA 1977).
Radding, S. B.; et_ aL.- Review of the environmental fate of selected
chemicals. Stanford Res. Inst. Office Toxic Substance U.S. Environmental
Protection Agency, Washington, D.C.; 1977. (As cited in USEPA 1979b).
Rosenberg, R.: Grahn, 0.; Johansson, L. Toxic effects of aliphatic chlorinated
byproducts from vinyl chloride production on marine animals. Water
Research 9:607-612; 1975.
U.S. Environmental Protection Agency (USEPA). Review of the Environmental
Fate of Selected Chemicals. Task 3. Final Report. Mo. EPA-560/5-77-003.
Washington, D.C., Office of Toxic Substances; 1977a.
U.S. Environmental Protection Agency (USEPA). Environmental Fate and
Effects. Chapter IV. Trichloroethylene. 1977b.
U.S. Environmental Protection Agency (USEPA). In-depth studies on health
and environmental impacts of selected water pollutants. Contract No.
68-01-4646. U.S. Environmental Protection Agency, 1978. (As cited by
USEPA 1980).
U.S. Environmental Protection Agency (USEPA). Trichloroethylene. Ambient
water quality criteria. Washington, D.C.: Criteria and Standards
Division, Office of Water Planning and Standards. 1979.
U.S. Environmental Protection Agency (USEPA). Ambient water quality criteria
for trichloroethylene. EPA 440/5-80-029. Washington, D.C.: Criteria and
Standards Division, Office of Water Regulations and Standards; 1980.
Walter, P.; Craigmill, A.; Villaume, J.: Sweeney, S.; Miller, G.
Chlorinated hydrocarbon toxicity(1,1,1-Trichloroethane trichloroethylene,
and tetrachloroethylene): A Monograph, ?B 257185/9WP. 1976. (As cited
in USEPA May 1977).
6-16
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7.0 RISK CONSIDERATIONS
7.1 HUMAN RISK
7.1.1 The Careinogenicity of Trichloroethylene
Considerable controversy exists concerning whether trichloroethylene
(TCE) is carcinogenic (see Chapter 5.0). Laboratory studies indicate
that technical ICE (1170 mg/kg body weight by gavage) is carcinogenic
in B6C3F1 mice, inducing an elevated incidence of hepatocellular
carcinoma. However, no tumors were seen in HarlCR Swiss mice intubated
with a considerably lower dose (0.5 mg purified TCE/mouse/week) for a
lifetime nor in mice fed 500 mg purified TCE/kg 5 times per week for
52 weeks. Repeated dermal application of TCE also produced no signi-
ficant incidence of skin tumors in Ha:ICR mice and initiation-promotion
studies were also negative. No carcinogenic activity was found in
Sprague-Dawley rats fed 240 mg purified TCE for 52 weeks, then held up
to 140 weeks; nor in Oshorne-Mendel rats given technical TCE by gavage;
however, high mortality reduced the ability to detect a carcinogenic
response in the latter study. No carcinogenic effects were observed
in Han:Wist rats, Syrian hamsters, or male Han:NMRI mice exposed to
2690 mg purified TCE/kg by inhalation for 18 months, although female
mice exhibited an elevated incidence of malignant lymphoma. The
significance of this finding, however, is questionable in view of the
30% incidence of lymphoma in controls. The malignant lymphomas in the
exposed population may be related to an immunosuppressive effect caused
by TCE.
The carcinogenic effects noted in B6C3F1 mice have thus been
questioned. Among several issues raised are:
• The presence of carcinogenic epoxide stabilizers in the
technical TCE sample administered to the B6C3F1 mice;
• The lower levels of epoxide hydrase in mice compared
with rats and humans;
• The high dosage levels employed which may have saturated the
usual metabolic pathways, resulting in atypical metabolites
and/or routes of metabolism. Perhaps these high levels
partially chemically hepatectomized the mice, with tumorigenesis
occurring secondary to rapid cellular proliferation and liver
regeneration.
7-1
-------
There is no epidemiologic evidence to suggest that TCE exposure is
associated with an increased risk of cancer in humans but cohort
aortalicy studies have only recently been initiated. Thus, the avail-
able evidence presented in this report (see Chapter 5.0 for additional
details) is insufficient to indict pure TCE as a carcinogen, but does
suggest that technical grade TCE may be a potential, but apparently
weak, carcinogen. Test studies currently underway will hopefully
clarify this issue. However, until such time as this issue is resolved,
a prudent course of action is to regard TCE as a suspected human
carcinogen.
The potential carcinogenic effects of TCE on humans were quantitatively
estimated through extrapolation of ^n vivo laboratory results (hepatocellular
carcinoma in B6C3F1 mice), using three extrapolation models. A discussion
of these models, as well as a number of important qualifications and
assumptions utilized in the estimation of equivalent human doses and the
extrapolation process, can be found in Section 5.1.3 of this report.
Exposure levels and doses to individuals have been estimated for
many different exposure conditions. These conditions consider inhalation
of TCE in air and ingestion of TCE in food and water. Risks associated
with body intakes for these different conditions are summarized in
Table 7-1. Non-occupational intakes due to inhalation range from 6 x 10~4
mg/day to 15 nig/day, with corresponding excess individual lifetime tumor
incidence probabilities (estimated) of 4 x 10~8 to 3 x 10~3. Estimated
excess risks due to continuous lifetime consumption of water contaminated
at average concentration levels are in the <10~7 to 10~*> range. At the
highest concentrations observed in drinking water, the estimated risk of
excess individual lifetime cancer is on the order of 10""3. These risk
levels are based on the assumption that these exposures occur continuously
over an individual's lifetime. Continuous lifetime exposures are most un-
likely to occur over a large fraction of the population, except for back-
ground inhalation levels.
Occupational exposures might be much higher than 15 mg/day, with a
corresponding increase in excess lifetime risk to populations exposed
in this way.
No data were available nor were any estimates possible concerning
the size of the population exposed to the chemical, except for the back-
ground inhalation value (0.6 ug/day). The total population potentially
exposed to this level is 220 x 10^. The background inhalation value
(0.6 ug/day) combined with the risk models yields a range of 8.8 to 22.
potential excess lifetime cancers for the 220 million people exposed,
or less than one excess cancer/year, assuming a 70-year lifespan.
7-2
-------
Table 7-1 ESTIMATED LEVELS OF HUNAN EXPOSURE AND EXCESS INDIVIDUAL 1.1 I'ETIME
PROBABILITY OF TUMOIl INCIDENCE DUE TO EXPOSURE TO TKICII1.0KOETIIYLENE
OJ
EXPOSURE
SITUATION
Background Air
LIFETIME
EXPOSURE
LEVEL OR
(muAlav)
0.0006
LIFETIME
EXPOSURE
LEVEL OR
DOSE^a)
(ing/kg/day)
8.6 x 10~6
RISK ESTIMATION METHOD
LINEAR MODEL
CAC MODEL (•>)
1 x 10~7
LOC-PKOIUT
MODEL (c)
) Excess
(c) Excess
(d) Excess
7 x 10
-7
1 x 10
-5
5 x 10
-4
1 x 10
-3
3 x 10
-3
< 10
-7
8 x 10
-7
8 x 10
-4
3 x 10
-3
7 x 10
-3
exposure (ing/day)/body weight (70 kg)
Lifetime Risk = (1.26 x 10-2)(mg/kg/day)-l * Dose (nig/kg/day)
* Dose (nig/day)
Lifetime Risk = * [-3.6 + log,fl(l)ose. ing/day)]
lifetime Risk = 6.5 x 10~5 (ing/day)-* * Dose (mg/day)
1.8 x 10-^
3 x 10
-7
4 x 10
-6
2 x 10
-4
4 x 10
-4
I x 10
-------
7.1.2 Other Human Risks Associated with TCE Exposure
Other Chan carcinogenic risk, the risks associated with chronic
exposure to TCE cannot be quantified. The effects of chronic exposure
to TCE in humans have not been extensively studied; therefore, they
are not well characterized. Intolerance co alcohol, however, is a
well-documented symptom of repeated TCE exposure and appears to be
related to a competitive inhibition between TCE and ethanol for micro-
somal mixed function oxidases, resulting in depression of TCE metabolism
and its subsequent build up in the blood.
Tests with laboratory animals have established no-observed-effect
levels of 540 to 2050 mg/m.3 over a 6-month exposure period. These levels
are orders of magnitude above estimated human exposure levels. No indi-
cations of fetotoxic or teratogenic effects of TCE have been reported
either.
Acute human exposure to TCE is of concern only at high exposure
concentrations. Inhalation of 800 mg3/m3 TCE for 2 hours can depress
the central nervous system. Reported symptoms include visual distur-
bances, mental confusion, fatigue, tremors, dizziness, nausea and vomiting.
These effects are reversible when the exposed individual is removed from
the source. High acute doses have produced cardiac arrhythmias, with
deaths typically caused by ventricular fibrillation and cardiac arrest.
Ingestion of 150 ml TCE can result in acute renal failure and cardiovascular
damage; however, little liver toxicity has been observed in humans. The'
lowest oral lethal dose reported for humans is 50 mg TCE/kg bw. Prolonged
skin contact may cause local irritation and blister formation; paralysis
of the fingers has been reported after repeated, intermittent immersion
of the hands in TCE.
7.2 RISK TO AQUATIC ORGANISMS
Ambient environmental levels of TCE appear to pose little risk to
aquatic organisms. Water concentrations range from none detected to a
high of 5300 ug/1 in the vicinity of a TCE manufacturing facility.
STORET retrievals indicate that most ambient concentrations seem to be
in the 10 ug/1 or less range. These concentrations, except for the
high levels detected in the vicinity of the manufacturing plant, are
generally lower than concentrations at which adverse effects have been
noted.
The lowest LC5Q to fish was found to be 16 mg/1 and sublethal
effects were found to occur at 2 mg/1. The lowest concentration for
adverse effects in algae was 8 mg/1. These concentrations are approxi-
mately two to three factors of ten greater than the generally observed
environmental concentrations. In the vicinity of manufacturing plants,
however, maximum water concentrations are comparable to levels at which
adverse effects have been noted. It is in these locations that TCE may
pose a threat to aquatic organisms if discharges occur at levels that
raav cause acuta or chronic effect levels to be reached.
7-4
-------
APPENDICES A-G
These appendices contain supporting information for Chapter 3. The
references for these appendices appear at the end of Chapter 3.
-------
APPENDIX A
The reaction for direct chlorination of 1,2-dichloroethane to
tri- and tetrachloroethylene is:
2 C1CH2CH2C1 * 5C12-*C12C=CHC1 + C12C=CC12 + 7HC1
The chlorination is carried out at temperatures between 400°C to
450°C, at approximately atmospheric pressure, and without the use of a
catalyst. Other chlorinated C? hydrocarbons or recycled
chlorinated hydrocarbon by-products may be used as feedstocks.
By-product hydrogen chloride is typically used in other processes.
Figure A-l represents a simplified process for manufacture of
tri- and tetrachloroethylene via direct chlorination of
1,2-dichloroethane. 1,2-Oichloroethane and chlorine are first
vaporized and fed to the reactor. Hydrogen chloride is separated from
the reaction mixture and recovered as a by-product. The chlorinated
hydrocarbon mixture is neutralized with sodium hydroxide solution.
The crude product is dried and separated by distillation into two
crude streams. Crude trichloroethylene is distilled and the light
ends taken overhead. The bottom stream which contains
trichloroethylene and heavy chlorinated hydrocarbons is distilled in
the finishing column. Trichloroethylene is taken overhead and sent to
storage; the heavy by-products are combined with the light ends from
the trichloroethylene column and recycled. The crude tetra-
chloroethylene is separated in the tetrachloroethylene column;
purified tetrachloroethylene goes overhead to storage and the bottoms
go to the heavy ends column. The heavy by-products are fractionated
and recycled. The bottom product (largely tars) is assumed to be
incinerated.
A-l
-------
to
AIR
AIR AIR AIR
iso-I H
.« f/ftl'-w
MtUTCM.
TO
AIR
L
•4- _ _ _.
1
AIR
ri-
I | •-
AIR
COUUMM
Jl
u
T
I J »- LO*,
HEAN/V
Figure A-l. Flow Diagram for Tetrachloroetylene by Chlorination (EPA. 1979d)
-------
APPENDIX 3
OXY-CHLORINATION
Tri- and tetrachloroethene may also be produced by oxy-chlori na-
tion of 1,2-dichloroethane:
5C1CH2CH2C1 + 3d 2 + 402 * ClgOCClg + 4C12C=CHC1 + SHgO
The reaction Is carried out at an approximate temperature and
pressure of 425°C and one atmosphere, respectively. Other chlorinated
hydrocarbons may be used as feedstocks; Indeed, most organic
by-products may be recycled to the process. The process Is relatively
flexible and production of either tri- or tetrachloroethylene may be
increased at the expense of the other.
Figure B-l represents a simplified process for tri- and
tetrachloroethylene manufacture via oxy-chlorination of
1,2-dichloroethane. Hydrogen chloride (or chlorine), oxygen, and
1,2-dichloroethane are vaporized and fed to a fluidized bed reactor.
The crude product is cooled, separated 'from by-product water and
noncondensed phases (e.g., carbon dioxide, hydrogen chloride nitrogen,
and small amounts of uncondensed chlorinated hydrocarbons) and are
scrubbed with process water to make by-product hydrochloric acid.
The remaining inert gases are purged.
The crude product is dried by azeotropic distillation and
separated into two product streams in the tetrachloroethene/
trichloroethylene column. Crude trichloroethylene is further
fractionated and low boiling impurities (light ends) are recycled to
the reactor. Trichloroethylene is neutralized with ammonia, dried,
and sent to storage.
B-l
-------
MAKEUP
• 00
' I
• ro
~L
,C"i xT7~i_
v4 42> V
" «ce«5| I
I fcillMCl
1^ _, j L^ I
MCI
A:'.a3ce*-<.
AIR
AIR
iOrCtL3CIH.3tt.ir. ACtO
AI
j*i?
—*-—^.
r
c£i
1
AIR
>JL
FLUID ttXr>
!l£>~fi>|i
A»jt>
C«iYliJ^-
CCL.UMU
ITT
•d |
AIR
T7
IKlCHLCXO-
ETHYLeuC
COUL.MM
-J
TO
pv/tiTV'6
CO.UMK!
AMIAMllA
CO.YE.%
J-,
J L_
R.1C.YC
«,YSf«
DC
l£
1
H
E
C
^|
k
HEAVY
EiaO^t
COUUMM
ETMYLElJfi
COCUMM
Figure B-l. Flow Diagram for Tetrachloroethylene and Trlchloroethylene
by Oxy-chlorinatlon (EPA, 1979d)
AIR
r—n AI
I L^yr.xoiws
, • LI
ptccnio. .1-
I Erti^ru'.
_ i ..
s.r*-*-Vv-
-------
Table C-l. TRICHLOROETHYLENE DISTRIBUTION IN POTWs, SLUDGE: Selected Urban Sites
r>
PLANT
1
2
3
4
5
6
7
AVERAGE FLOW
(lOp I/day)
400
30
38
340
95
23
190
TRICIILOROETIIYLENE CONCENTRATON (ii
-------
Table D-l. Incidents Involving Trichloroethylene (January 1971 through March 1980)
Can ler
Shipper
Juhnsun Hoi or I Ines Inc.
U.S. Guvernmunt - 111)0
I'ALitii. Inlcrmounlitlo Lxpress
U.S. Government - DUII
luicry Air freight Corporation
Uurke Kublier Company
llintdh freiglitways
U S. liiivcriunuiit - USA
Associated Truck Lines Inc.
Nallinckroilt Chemical Works
Uyiolf Coni|iany Inc
IIUR Scientific Company
CaiHjo Corporation
Ikiw Iheiuical Company
Ashland Chemical Company
Ashland Chemical Company
Associated truck Lines Int..
Uulk lenninals Company
Hoile
Date
llwy
6/20/77
llwy
11/21/76
Air
II/I/7II
llwy
?/l//9
llwy
3/«J/79
llwy
3/14/79
llwy
3/IU/79
llwy
5/3/79
llwy
111/27/79
Inriiliiiit location
Shipment Origin
Atlanta
llcllhluir
Peterson fid.
Lyolh
San 1 ranclsco
San Jose
Salt Lake Cy.
llonvor
Louisville
St. Inuls
Salt lake Cy.
Denver
Iowa
frrepnrt
Cnlimiliiis
Columbus
Alslp
Cliltaijo
dA
VA
CO
CA
CA
CA
III
CO
KV
MO
Ul
CO
IA
IX
flll
Oil
IL
IL
Container
lypus Capacity(l)
Injury/Dead
Hetal drum*
Metal can
Metal drum1*
Hetal druinb
Class bottle ft
1 ihcrlioard box
or carton
Tank truck
Cargo tank
Hetal drunb
20
0 0
0 0
4
0 0
210
0 0
210
0 0
4
0 0
0
0 0
15140
0 0
210
0 0
1 at lures Ami
Damages
Uoltom fall.
t20
JO
loose fittings
to
external punct.
130
Improper braclnq/
damage by other
Iri-ight
iioo
Body/side fall.
to
Vehicular ace id.
to
Hose burst
13116
Internal uunct.
tis
. Hel<.M*4!ll(l)
Result
1
spill
20
spill
4
spill
10
spill
III)
spill
4
spill
4
Spill
b!iS
spill
4
spill
Source: Department of Transportation, 19110
a) Removable head authorized
b) Removable hsad not authorized
-------
Table E-l. National Organic Monitoring Survey, March 1976 through January 1977: Trichloroethylene
Number of Positive Analyses
per Mean Concentration (wg/1) Median Concentration (iig/1)
Number of Analyses Positive Results Only All Results
Sample Phase8 I II III I II III I II III
Quenched6 4/112c 10/106 llc 2.4
-------
1. Recycle = (x)Waste Solvent, where x = 45%
2. Total Use = Virgin Solvent + Recycle
« Virgin Solvent + (x) Waste Solvent
3. Waste Solvent = (y)Total Use = (y)(Virgin + (x)Waste)
y, the fraction wasted, is derived from Table F-2:
38,000 out of 117,000 kkg virgin solvent
is wasted:
y « 38,000/117,000 = 0.325
Solving for Waste Solvent in Equation 3:
Waste = (y)Virgin Production + (x)(y)Waste
Waste (l-(x)(y)) = (y)Virgin
Waste = y Virgin = 0.38 Virgin
From Equation 1:
Recycle = (x)waste
= (x)(0.38)Virgin = 0.171 Virgin
Figure F-l. Calculations: Total Solvent Usage in Degreasing
Operations
F-l
-------
Table F-l. Industrial Classes Utilizing Degreasing
Source Type SIC
Industrial degreaslng
Metal furniture 25
Primary metals 33
Fabricated products 34
Nonelectric machinery 35
Electric equipment 36
Transportation equipment " 37
Instruments and clocks 38
Miscellaneous 39
Automotive
Auto repair shops and garages 75
Automotive dealers 55
Gasoline stations 55
Maintenance shops a
Textile plants (fabric scouring) 22
Source: EPA, 1979b.
aNo applicable SIC for this category
F-2
-------
I'/.1/1
• I,'/ f '
WASTE
SOLVENT
Figure F-2. Cold Cleaner (EPA, 1977a)
F-3
-------
DIFFUSION AND
CONVECTION
Figure F-3 Open-Top Degreasing Emission Points
Source: EPA, 1977a.
Figure F-3. Open-Top Degreasing Emission Points (EPA, 1977a)
-------
i
en
DIFFUSION AND
CONVECTION
CONDENSER^
COILS
Figure F-4 Conveyorized Degreaser Emission Points
Source: tPA, 1977a.
Figure F-4. Conveyorized tiegreaser Emission Points (EPA, 1977a)
-------
. , Ventilator
AA Exhaust
I21!h?ndts t. Dragout
Outlet
Losses—••
\ SCOURING MACHINE /
WASTE SOLVENT
DISPOSAL
Figure F-5. Fabric Scourer (EPA, 1979b)
F-6
-------
APPENDIX G
G.I PHYSICAL PROPERTIES AND AMBIENT LEVELS
This section describes the physical properties of trichloro-
ethylene and ambient levels in air, water and soil. Included is a
list past damage incidents arising from improper disposal or storage
of trichloroethylene-containing waste. Cumulative emissions from
degreasing operations have been estimated for the past 20 years, with
emphasis on waste solvent dispersion (see Section 3.5.2).
G.I.I Physical Properties
Trichloroethylene (CHC1=CC1 ) is a colorless, sweet smelling,
volatile liquid at normal temperatures. Its physical properties are
listed in Table G-l. The fact that it is nonflammable under conditions
of normal use and miscible with many organic liquids makes it a
versatile solvent with many industrial applications, primarily in
metal degreasing.
G.I.2 Ambient Levels of Trichloroethylene
Trichloroethylene is found in all media of the environment. It
is, however, not ubiquitous and available literature indicates it is
solely man-made (Derwent and Eggleton, 1977). Like other low
molecular weight (C^-C^) chlorinated hydrocarbons,
trichloroethylene has a relatively high vapor pressure and low water
solubility and thus, tends to partition toward the atmosphere.
G. 1.2.1 Atmosphere
In air, trichloroethylene is found in the part per trillion (ppt)
range (see Table G.2), with concentrations highest near urban areas
(Lillian, et a].., 1975; Singh, et iL-« 1977a; Correia, et li-, 1977;
EPA, 1977b"J7 The OSHA recommended occupational exposure standard is
100 ppm, averaged over an eight hour workday, and is based on the
threshold limit value established by the American Conference of
Governmental Industrial Hygienists (ACGIH, 1976). Trichloroethylene
is thought to be rapidly oxidized in the atmosphere (NAS, 1975; Gay,
ejt al., 1976; Dilling, et £l_.f 1975), giving rise to toxic products
sucTTas phosgene (Lillian, et al_., 1975) and chloroacetyl chlorides
(Singh, et aj_., 1977a). A detailed discussion of the photochemical
fate of trichloroethylene, however, is beyond the scope of this
materials balance.
G.I.2.2 Water
Levels of trichloroethylene in water vary with the degree of
pollutant contamination. Levels in surface waters of industrialized
G-l
-------
Table 6-1. Properties of Trichloroethylene
molecular weight
melting point. *C
boiling puini. "C
specific gravity
liquid
20/4«C
100/4«C
vapor" at bp
vapor density at bp. kg/ra3
no
liquid. 20°C
vapor. 0°C
viscosity. mPa-» (• cP>
liquid
20"C
60«C
vapor at 6Ce
surface tension at 20°C. m.N 'm' • dyn/cm)
heat capacity at 20°C. J/(kg-Kir
liquid
vapor
critical temp. *C
critical pressure. MPa'
thermal conductivity. W/(m-K>
liquid
vapor, at bp
coeff cubical expansion, liq. 0-*0°C
dielectric constant, liquid, at 16'C
dipole moment. C-m"
heat of combustion. MJ/kg*
heat of formation. MJ/(kg-mo2>*
liquid
vapor
latent beat of evaporation at bp. kJ/kg*
explosive limits, vol ^ in air
25°C
100»C
vapor pressure'. kPa'
Antoine constants
solubility, g
H;0 in 100 g trichloroethylene
O'C
20*C
60*C
trichloroethylene in 100 g HjO
20*C
60°C
13!
SS.T
1.46S
4.54
4.45
1 4782
1.001 744
0.56
0.42
A
194606
26.4
941
653
271.0
5.02
138.5
8.34
0.00119
3.42
3.0 x 10-
7J25
4.18
-29.3
240
8.0-10.5
8.0-52
B
1187.51
0.010
0.0225
0.08G
0.107
0.124
C
214.474
• Air • 1.
• To convert J to cal. divide by 4.184
' To convert MPa to aim. divide b> 0. 1 01 .
' To convert C-m to debye. divide b> 3.336 x 10' *
/ To convert kPa to mm Hg. multiply by 7.5.
Source: McNeil!, 1979.
G-2
-------
Table G-2. Ambient Levels of Trichloroethylene In Air
OJ
Air Levels Comments
0.05-8.8 ppba Measurable primarily near urban areas. Precursor of phosgene.
16±8 ppt" Northern hemisphere. Southern hemisphere background concentrations <3 ppt
20 pptc . Averaged tropospherlc background concentration.
5-15 ppt Lower troposphere
2.6-3.3 npbe -Urban
14.5 ppt' Significant urban-nonurban gradient
15.6 ppt9 N. hemisphere background concentration
16 ppt" . Ambient concentration in industrialized areas
I ppt-100 ppb Remote areas Manufacturing areas (range)
2-16 pptJ. Ambient concentrations in industrialized areas in U.S.
0.1-3 ppb Western Europe concentration higher in urban areas than near manufacturers
a) Lillian. £t ^K, 1975
b) Simjh, et al.t 1979
c) Cronn, tilt TT., 1977
d) Oerwent amFEggleton, 1978
e) Ohta, et al, 1977
f) Singh, et al., 1977a
g) Singh, et IT., 1977b
h) EPA, 1976a~~
1) EPA, 1977
j) EPA, 1979b
k) Correia, et al., 1977
-------
Table G-3. Ambient Levels of Trlchloroethylene In Mater
Water Levels
<5 ppb
0.02-25 ppb
Trace amounts (slppb)
4.1-70 ppb
Trace - 6700 ppb
1-21 ppb
0.1-32 ppb
£ 10 ppm
£ 260 ppm
0-188 ppb
Comments
Surface waters of industrialized river basins, average concentration
Rivers, canals, seawater in Europe
Drinking water
Municipal wells
Production wells near trichloroethene storage tanks on Air Force Base
Drinking water in various cities
Drinking water in various cities
Wells near lagoon receiving waste from tool manufacturer
Wells near sanitary landfill
Great Lakes area, water plus suspended sediment
en
•*»
a) EPA. 1977b
b) Correia, et aK, 1977
c) Thomason, et al., 1978
d) Joyce, 1979; "See Section 3.5.1
e) Grimes, 1980; See Section 3.5.1
f) EPA, 1970a
g) EPA. I979c
h) EPA, 1979c
i) Council on Environmental Quality, 1978
-------
areas are generally in the part per billion (ppb) range (see Table
G-3). Levels in groundwater and municipal water supplies (e.g.,
wells, reservoirs) may be much higher, as a result of improper storage
or disposal practices (e.g., leaching from landfills or leakage from
storage facilities; see Table G-3 and Section 3.5.1 for documented
levels of trichloroethylene contamination in well water of up to 260
ppm). Furthermore, chlorination of drinking water is a potential, yet
apparently insignificant, inadvertent source of trichloroethylene (see
Section 3.3.5.2). Contamination of a waterbody may result from
ongoing discharges or from previous incidents in which contaminated
water moved slowly and with little mixing through an aquifer (Walker,
1973). While trichloroethylene evaporates readily from agitated
aqueous systems (NAS, 1975; Helz and Hsu, 1978; Oil ling, et al.,
1975), it may persist unchanged in undisturbed water bodies TT.e.,
plug flow). Evaporation of trichloroethylene from water is a more
likely route of removal than by hydrolysis, biodegradation, or
transfer to sediments (NAS, 1975; Helz and Hsu, 1978).
Data concerning ambient levels of trichloroethylene in soil and
sediment are scarce, although levels of up to 7 ppm have been
documented (EPA, 1979c). Major sources of trichloroethylene discharge
to soil are leaching from landfills, illegal dumping, and subsurface
waste injection. Trichloroethylene may also enter soil by injection
of fungicides into crop land. From there it may evaporate (the most
likely route), be leached away, or be taken up by plants. It is not
known whether soil adsorption of trichloroethylene is a significant
phenomenon.
G.2 ENVIRONMENTAL DAMAGE INCIDENTS
Table G-4 is a summary of documented U.S. environmental damage
incidents involving trichloroethylene (see Section 3.5 for a
discussion of waste mismanagement).
fi-5
-------
Table G-4. Recently Documented Damage Incidents as a Result of Improper Waste Management of Trlchloroethylene
Location
Suspected/Conf1raed
Generator. Trtchloroethene Use
Disposal Method/
Source of Pollution
Trichloroethene
Contamination
tn
ct
Rancho Cordova. California
San Gabriel Valley.
Los Angeles, California
Mather AFD. California
HcClellan AFB. California
Southington. Connecticut
Canton. Connecticut
East Gray. Maine
Gray. Maine
Aerojet General/
Cordova Chemical:
solvent during production
and delivery of rocket
propellant
Not specified
Oegreasing, cleaning of
machinery on base
Solvents recovery service:
distillation, recovery and
disposal of Industrial
solvents
John Swift Chemical Company
Waste disposal site accepting
1-2x10* gal/yr of waste oil
and various liquid wastes
Solvent and oil waste
processing facility
Open pit. old dredge pit.
Unllned and defectively lined
surface percolation ponds
Not specified
Old Industrial sludge pits.
settling ponds, underground
storage tanks
Not specified
Not specified
Tanks or 1/2-acre asphalt-
lined lagoon
Not specified
Ground water to Dredye pit;
25-30/50 private wells
sampled within 0.5 mile of
Aerojet property
56 municipal wells within
18 water supply systems
16.5-30.2 ppb in drinking
water wells
several wells, on and off
base
groundwater: three of six
wells closed, two of these
three contained hazardous
levels of trlchloroethene
11 Canton wells
20 nearby residential wells
Residential well
-------
Table G-4. (Continued)
en
location
Massachusetts:
Ac ton North Reading
Uudford Norwood
(lelcherluwn Rehoboth
Hiirlington Rowley
Canton Shrewsbury
Danvcrs Woburn
Groveland Wilmington
Luncnbery Vanmuth
Oscoda. Michigan
Caiiiden. Now Jersey
Ht. Holly. New Jersey
Niagara Falls. New York
(Hyde Park site)
Ilidipra Falls. New York
(Love Canal site)
Suspected/Confirmed
Generator. Triclilorocthenc Use
Various: unidentified dumpers,
industries using degreasers (ey.
electronics, machine shops)
None identified
Harrison Avenue landfill
- active until 1976
Landfill and Development
Company
1953-1975 Hooker Chemical
1942-1952 Hooker Chemical
Islip (Suffolk County). New York
Mickey's Carting
Disposal Method/
Source of Pollution
Illegal discharge into leaking
sewer lines, illegal dumping of
55 gallon drums to unlined
sites, discharge from septic
leach lines
Open dumping of trlchloroethene
on site of nearby auto parts
plant
Abandoned gravel pit - hazardous
materials dumped with municipal
trash
20 acre landfill on banks of
Rancocos Creek, adjacent to
housing developments - no liner
15 acre landfill, two drainage
ditches emptying into tributary
of Niagara River
Landfill - two 70 foot strips
on either side of 60 foot canal
Town dump
Trichloroethene
CoiilaniLn.it joti
Private wolls, municipal
supplies: ii|> to 100Z
contamination in some areas
Eight private wells and one
Industrial well
Leachate over tidal mudflats
to Delaware River - nearby
residential population
Private water wells, ground-
water
Migration from landfill.
hazardous levels
Migration from landfill at
hazardous levels; 239 homes
and grammar school built on
land around canal; 3 storm
sewers underlie the landfill.
emptying into a tributary of
Niagara River, which contains
hazardous amounts in water
and sediment
4xl03 gallons of industrial
cleaner trichloroethene
dumped; numerous area wells
showed trichloroL'lhene
-------
Table G-4. (Concluded)
00
Location
West Nyack. New York
Ducks and Montgomery Counties.
Pennyslvania
Newbery Township, Pennsylvania
Hazel ton. Pennsylvania
Lchigh County. Pennyslvania
North SmUhfleld. Rhode Island
Bristol, Rhode Island
Suspected/Conf1 nned
Generator. Trlchloroethene Use
None determined; various
Industries within one mile of
site used trlchloroethene
None determined
One company, not named
From New Jersey, midnight dumpers
None determined
Chemical wastes and septage of
undetermined origin
None determined
Disposal Method/
Source of Pollution
Not specified
12 active sites under
investigation
Not specified
Dumped Into quarry
lleleva landfill
Western Sand and Gravel
- trenches and unllned
lagoons: sand and gravel
>663 barrels In three Illegal
dump sites
Trlchloroethene
Contamination
16 private wells closed
Private wells, camp and
municipal water supplies
Private wells
Leakage to aquifer.
potential water supply
contaminated
Well supplying 50 homes
Leaching to brook and
reservoir
Adjacent marshland,
>11 wells
Source: EPA, 1980a, except Massachusetts incidents, which are from Massachusetts. 1979.
------- |