Toxic Tort: Trichloroethylene in Residential Water Supply
This case study summarizes the events surrounding the filing of a lawsuit by residents
against a company for allegedly contaminating the local water supply with trichloroethylene,
a chemical used in industrial cleaning and degreasing. It further illustrates how
exposure evidence, historical factors, a residential questionnaire and a toxicological
risk assessment can play pivotal roles in determining an outcome in litigation.
TCE (1,1,2-trichloroethane or "trichloroethylene") is a colorless, transparent liquid used in manufacturing.
It previously served as a degreaser, paint stripper, adhesive solvent and as an
additive in paints and varnishes as well as in the manufacture of other chemicals.
It is nonflammable at room temperature and evaporates readily into the air. TCE
can leach into groundwater when improperly disposed of.
TCE and vinyl chloride are confirmed human carcinogens associated with non-Hodgkin's
lymphoma, leukemia, kidney and liver cancer and other malignancies. Vinyl chloride
is known to cause certain types of liver cancer.
Historically, people have been exposed to TCE through ingestion of contaminated
groundwater and by inhaling vapors resulting from soil vapor intrusion. In this
case, residents ingested TCE through well water and vapors evaporated from
contaminated drinking water into indoor air during cooking, cleaning and washing,
resulting in a quantifiable exposure dose.
Chronic Ingestion of TCE and Vinyl Chloride from Contaminated Well Water
Eighty-eight residents commenced an action for personal injury and property damages
due to defendants' alleged contamination of groundwater and drinking wells with
trichloroethylene (TCE) and vinyl chloride. Plaintiffs claimed that the TCE and
vinyl chloride emanated from property formerly used by defendant to manufacture
electrical components. The plant used TCE and other solvents to clean component
parts from approximately 1962 to 1967 with spent solvent disposed of in an on-site,
unlined "evaporation pit."
In 1979, the defendant sampled the soil near one of the abandoned pits and detected
chemicals within the soil. In 1985, the defendant hired an environmental company
to further assess their industrial site and found TCE within the groundwater at
levels thousands of times in excess of the state drinking water standard. However,
the defendant notably failed to alert the nearby residents of these test results.
The defendant also failed to test any of the plaintiffs' local drinking water wells.
As a result of this inaction, the plaintiffs were needlessly exposed to TCE for
an additional 15 years at which time governmental agencies finally initiated independent
testing (year 2000).
Toxicological Assessment of TCE and Vinyl Chloride Exposure
To assess the claim, the plaintiffs' expert hydrogeologist modeled historic well
water TCE levels at each plaintiff's location. Dr. Sawyer prepared a residential
screening questionnaire to ascertain TCE exposures via ingestion quantity, dermal
absorption and inhalation using generally-accepted, peer-reviewed methodology. The
results of the questionnaire were compiled and presented in court to demonstrate
dose and the documented and potential effects of TCE and vinyl chloride exposures in
well water. Additionally, Dr. Sawyer prepared a toxicological
health risk assessment based on the exposure parameters of the 88 plaintiffs and
an assessment of potential malignancies supported by human toxicological and epidemiological
Dr. Sawyer was challenged by the defendant with numerous pre-trial arguments within
motions to exclude. All of these motions were subsequently denied by the court.
Notable Toxicological Factors Assessed by Dr. Sawyer
- Risk assessment results were based on a generally-accepted, peer-reviewed methodology.2
- The TCE well water level (average of all homes) exceeded the U.S. EPA Maximum Contaminant
Level (MCL) by more than 7 times (average of plaintiff wells = 36.11 µg/L vs.
the MCL of 5.0 µg/L.)3
- Historic TCE well water levels exceeded the U.S. EPA Residential Screening Level (RSL)
by more than 15 times (average of plaintiff wells = 31.94 µg/L vs. the RSL
of 2.0 µg/L.)
- The cancer risk assessment value exceeded the U.S. EPA benchmark value for "significantly
- Met requirements for medical monitoring candidacy per ATSDR under CERCLA as published
in the Federal Register.3
- TCE is a "confirmed human carcinogen." (ATSDR)1
- Vinyl chloride is a "confirmed human carcinogen." (ATSDR)4
Subsequent to presentation of Dr. Sawyer's report, the U.S. National Toxicology
Program, the International Agency for Research on Cancer (IARC) and the U.S. EPA determined
(through peer-reviewed studies) that sufficient, scientifically credible evidence
existed that trichloroethylene exposure can induce several different types of cancer.
In 2015, the National Toxicology Program (NTP) recommended a change in TCE's cancer
classification to Group 1 ("Known Human Carcinogen").5
A protracted, three week trial ensued during which Dr. Sawyer offered expert testimony
with respect to his toxicological assessment and formal report. In view of the overwhelming
toxicological evidence, the demonstrable negligence in failing to alert residents
and failing to test residential drinking water wells for contamination, in addition
to the fact that the court denied all motions to exclude expert testimony damaging
to their position in litigation, defendants elected to settle the case prior to
a likely verdict in favor of plaintiffs.
In toxicological cases, weight-of-evidence (WOE) determinations can greatly affect
the outcome. Dr. Sawyer successfully rebutted repeated motions-to-exclude by virtue of the application
of unbiased, peer-reviewed methodologies and by drawing upon documented and historical
facts-in-evidence during expert testimony and depositions. The comprehensive report(s),
expert opinions and compilation of questionnaire data presented in court were instrumental
in bringing about a conclusion to this case. TCAS strongly recommends that
any individual, company or government agency engaged in litigation matters concerning
exposure to TCE and/or vinyl chloride always retain the services of an experienced,
impartial expert toxicologist.
(Disclaimer: Toxicology case studies are impartial and objective summaries of toxicological
matters in which TCAS was retained for the purpose of assessing health-based
factors which, in some cases, led to a determination of causation. No names or identifying
information have been provided due to privacy and legal considerations. In the above
matter, Dr. Sawyer was retained by plaintiffs.)
Notes and References
- ATSDR, Division of Toxicology and Environmental Medicine, "Toxicological Profile for Trichloroethylene," 2014
- U.S. EPA, "Trichloroethylene Hazard Summary,"
- Federal Register, U.S. EPA, "Trichloroethylene Health Risk Assessment,"
2001, Vol. 66, No. 227
- ATSDR, Division of Toxicology and Environmental Medicine, "Toxicological Profile for Vinyl Chloride,"
- National Toxicology Program, "Report on Carcinogens:
Monograph on Trichloroethylene," U.S. Department of Health and Human Services,
- Image by Keith Beard, Salt Lake City, UT