United States
Environmental Protection
Agency
Office of Water
4601
EPA811-F-95-004h-T
October 1995
National Primary Drinking
Water Regulations
1,1 -Dichloroethylene
CHEMICAL/ PHYSICAL PROPERTIES
CAS NUMBER: 75-35-4
COLOR/ FORM/ODOR: Colorless liquid with a
mild, sweet, chloroform-like odor
M.P.: -122.5° C B.P.: 31.7° C
VAPOR PRESSURE: 591 mm Hg at 25° C;
highly volatile
OCTANOL/WATER PARTITION (Kow):
Estimated log Kow= 1.32
DENSITY/SPEC. GRAV.: 1.213 at 20° C
SOLUBILITIES: 2.5 g/L of water at 25° C
SOIL SORPTION COEFFICIENT: Koc estimated
at 150
ODOR/TASTE THRESHOLDS: N/A
BIOCONCENTRATION FACTOR: N/A; not ex-
pected to bioconcentrate in fish.
HENRY'S LAW COEFFICIENT: N/A
TRADE NAMES/SYNONYMS: 1,1-DCE; 1,1-
Dichloroethene; Asym-dichloroethylene;
Vinylidene chloride;
DRINKING WATER STANDARDS
MCLG: 0.007 mg/L
MCL: 0.007 mg/L
HAL(child): 1 day: 2 mg/L
Longer-term: 1 mg/L
HEALTH EFFECTS SUMMARY
Acute: EPA has found 1,1-dichloroethylene to poten-
tially cause adverse liver effects due to acute exposures
at levels above the MCL.
Drinking water levels which are considered "safe" for
short-term exposures: For a 10-kg (22 Ib.) child consum-
ing 1 liter of water per day: a one-day exposure of 2 mg/
L; upto a 7-year exposure to 1 mg/L.
Chronic: Chronic exposure to 1,1-dichloroethylene
at levels above the MCL has the potential to cause liver
and kidney damage, as well as toxicity to the developing
fetus.
Cancer; There is some evidence that 1,1-
dichloroethylene may have the potential to cause cancer
at levels above the MCL.
USAGE PATTERNS
An estimated 90,700 tons/yr of the monomer were
produced in the USA during the early 1980s. Virtually all
of the 1,1-dichloroethylene produced is used in the
production of copolymers with vinyl chloride or acryloni-
trile. A small percentage (4%) of 1,1-dichloroethylene is
used as chemical intermediates. These products are
then used in adhesives, synthetic fibers, refrigerants,
food packaging and coating resins such as the saran
types.
RELEASE PATTERNS
1,1-Dichloroethylene may be released into the envi-
ronment as emissions or in wastewater during its produc-
tion and use in the manufacture of plastic wrap, adhe-
sives, and synthetic fiber. 1,1-Dichloroethylene is formed
by a minor pathway during the anaerobic biodegradation
of trichloroethylene and also by the hydrolysis of 1,1,1-
trichloroethane. Therefore there is a potential for it to form
in groundwater that has been contaminated by chlori-
nated solvents. 1,1 -Dichloroethylene is also produced by
the thermal decomposition of 1,1,1-trichloroethane, a
reaction that is catalyzed by copper. 1,1,1 -Trichloroethane
is used as a degreasing agent in welding shops so there
is a potential for 1,1-dichloroethylene to be formed in
these shops as well as in other industrial environments
Toxic RELEASE INVENTORY -
RELEASES TO WATER AND LAND:
1987 TO 1993
TOTALS (in pounds)
Top States:
KY
TX
LA
Major Industries
Plastics materials, resins
Alkalies, chlorine
Water
10,101
2,880
2,06'
2,079
3,942
4,173
Land
1,488
286
150
3
1,299
154
October 1995
Technical Version
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where 1,1,1 -trichloroethane is used near sources of heat.
From 1987 to 1993, according to the Toxics Release
Inventory, releases to water totalled over 10,000 Ibs.
Releases to land totalled about 1,500 Ibs. These re-
leases were primarily from facilities classified as produc-
ing alkalies/chlorine and plastics materials/resins. The
largest releases occurred in Kentucky.
ENVIRONMENTAL FATE
Releases to water will primarily be lost to the atmo-
sphere through evaporation. The mass transfer coeffi-
cient between water and the atmosphere of 1,1-
dichloroethylene relative to oxygen has been measured
to be 0.62. Using data for the oxygen re-aeration rate of
typical bodies of water, one can calculate the half-life for
evaporation of 1,1 -dichloroethylene to be 5.9,1.2 and 4.7
days from a pond, river and lake, respectively. In water,
the photooxidation of 1,1-dichloroethylene is insignifi-
cant. A hydrolysis half-life of 6-9 months has been ob-
served with no significant difference in hydrolysis rate
between pH4.5 and 8.5. This value differs markedly from
the estimated hydrolytic half-life of 2 yr at pH 7.
If spilled on land, part of the 1,1-dichloroethylene will
evaporate and part will leach into the groundwater where
its fate is unknown, but degradation is expected to be
slow based upon microcosm studies. No experimental
data is available on the adsorption of 1,1 -dichloroethylene.
A low Koc of 150 are calculated from a regression
equation based on its octanol/water partition coefficient
(log Kow= 1.48).
Once in the atmosphere it will degrade rapidly by
photooxidation with a half-life of 11 hours in relatively
clean air or under 2 hours in polluted air.
Few studies on the biodegradation of vinylidene could
be found In one study, 45-78% of the chemical was lost
in 7 days when incubated with a wastewater inoculum;
however, a sizeable fraction of the loss was due to
volatilization. 97% of 1,1-dichloroethylene was reported
to be removed in a municipal wastewater plant but again
the fraction lost by evaporation is unknown.
Under anaerobic conditions in microcosms designed
to simulate the anaerobic conditions in groundwater and
landfills, 1,1-dichloroethylene undergoes reductive de-
chlorination to vinyl chloride. In the microcosms designed
to simulate a groundwater environment, 50% of the 1,1-
dichloroethylene disappeared in 5-6 mo.
Under the simulated landfill conditions, degradation
occurred in 1-3 weeks. In another anaerobic biodegrada-
tion study that used materials from an aquifer that receive
municipal landfill leachate and is known to support
methanogenesis, the 1,1-dichloroethylene disappeared
in 40 weeks. However, no significant degradation oc-
curred for 16 weeks. 1,1 -Dichloroethylene was formed as
a degradation product.
No experimental data could be found on the biocon-
centration of 1,1 -dichloroethylene in fish or aquatic inver-
tebrates. Based on its low octanol/water partition coeffi-
cient (log Kow= 1.48) one would not expect any signifi-
cant bioconcentration.
The general population may be exposed to low levels
of 1,1-dichloroethylene in ambient air, indoor air, con-
taminated drinking water, and food which has come in
contact with plastic wrap which contains residual mono-
mer.
OTHER REGULATORY INFORMATION
MONITORING:
FOR GROUND/SURFACE WATER SOURCES: •
INITIAL FREQUENCY- 4 quarterly samples every 3 years
REPEAT FREQUENCY- Annually after 1 year of no detection
TRIGGERS - Return to Initial Freq. if detect at > 0.0005 mg/L
ANALYSIS:
REFERENCE SOURCE
EPA 600/4-88-039
METHOD NUMBERS
502.2; 524.2
TREATMENT:
BEST AVAILABLE TECHNOLOGIES
Granular Activated Charcoal and Packed Tower Aeration
FOR ADDITIONAL INFORMATION:
* EPA can provide further regulatory and other general information:
• EPA Safe Drinking Water Hotline - 800/426-4791
* Other sources of toxicological and environmental fate data include:
• Toxic Substance Control Act Information Line - 202/554-1404
• Toxics Release Inventory, National Library of Medicine - 301/496-6531
• Agency for Toxic Substances and Disease Registry - 404/639-6000
October 1995
Technical Version
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