United States
Environmental Protection
Agency
Office of Water
4601
EPA 811-F-95-004r-T
October 1995
&EPA
National Primary Drinking
Water Regulations
1,1,1 -Trichloroethane
CHEMICAL/ PHYSICAL PROPERTIES
CAS NUMBER: 71-55-6
COLOR/ FORM/ODOR: Colorless liquid with
sweet, chloroform-like odor
M.P.: -30.4° C B.P.: 74.1°C
VAPOR PRESSURE: 127 mm Hg at 25° C
OCTANOL/WATER PARTITION (Kow):
Log Kow = 2.49
DENSITY/SPEC. GRAV.: 1.34 at 20° C
ODOR/TASTE THRESHOLDS: N/A
BIOCONCENTRATION FACTOR: Low; 8.9 in fish
HENRY'S LAW COEFFICIENT: 0.008 atm-cu m/
mole;
SOLUBILITY: Soluble in water; 4.4 g/L of
water at 20° C;
TRADE NAMES/SYNONYMS: Chloroethene; •
SOIL SORPTION COEFFICIENT: Koc is 81 in silty Methylchloroform; Aerothene TT;
clay, 89 in sandy loam. Algylen; Alpha-T; Chlorten; Gemalgene;
Genklene; Dowclene; Solvent 111;
Trichloran; Inhibisol
DRINKING WATER STANDARDS
MCLG: 0.2 mg/L
MCL: 0.2 mg/L
HAL(child): 1 day: 100 mg/L
Longer-term: 40 mg/L
HEALTH EFFECTS SUMMARY
Acute: EPA has found that 1,1,1-trichloroethane has
the potential to cause damage to the liver, nervous
system and circulatory system from acute exposures
above the MCL.
Drinking water levels which are considered "safe" for
short-term exposures: Fora 10-kg (22 Ib.) child consum-
ing 1 liter per day, a one-day exposure of 100 mg/L; upto
a 7-year exposure to 40 mg/L.
Chronic: 1,1,1 -trichloroethane has the potential to
cause liver, nervous system and circulatory system dam-
age from a lifetime exposure at levels above the MCL.
Cancer; There is inadequate evidence to state whether
or not 1,1,1-trichloroethane has the potential to cause
cancer from exposures in drinking water.
USAGE PATTERNS
Demand for 1,1,1-trichloroethane in 1988 was 700
million Ib., increased to 705 million in 1989, and was
projected (in 1989) to reach 735 million Ib. in 1993.
Solvent uses include vapor degreasing of metal prod-
ucts; for cleaning precision instruments; for textile pro-
cessing and dyeing; in aerosols, in which if acts both as
a vapor pressure depressant and as a solvent and carrier
for many of the active ingredients used in aerosols.
It is also used as an intermediate in the manufacture of
organic chemicals, as a coolant and lubricant in metal
cutting oils; as a component of inks and drain cleaners.
Agricultural uses have included postharvest fumigation
of strawberries; for degreening citrus fruits; as a solvent
for various insecticides.
Proportions consumed for various uses in 1989 were:
vapor degreasing, 34%; cold cleaning, 12%; aerosols,
10%; adhesives, 8%; intermediate, 7%; coatings, 5%;
electronics, 4%; other, 5%; exports, 15%.
Toxic RELEASE INVENTORY -
RELEASES TO WATER AND LAND:
1987 TO 1993
Water
TOTALS (in pounds) 222,403
Top Six States*
CA 0
GA 0
AR 0
IN 15,000
VA 0
UT 40,000
Major Industries
Gray iron foundries 1,084
Aircraft 546
Manufacturing industries 1,018
Wood furniture 0
Fabricated structural metal 0
Plating, polishing 6,152
Turbines, generators 40,317
Land
812,873
109,070
73,258
67,000
46,096
51,822
0
76,158
73,258
72,572
53,038
51,425
41,647
966
* State totals only include facilities with releases greater
than 10,000 Ibs.
October 1995
Technical Version
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RELEASE PATTERNS
1,1,1 -Trichloroethane is likely to enterthe environment
from air emissions or in wastewater from its production or
use in vapor degreasing, metal cleaning, etc. It can also
enter the environment in leachates and volatile emis-
sions from landfills.
From 1987 to 1993, according to EPA's Toxic Chemi-
cal Release Inventory, releases to water totalled over
222,000 Ibs. Releases to land totalled over 812,000 Ibs.
These releases were primarily from metal fabrication
industries. The largest releases occurred in California
and Georgia. The largest direct releases to water oc-
curred in Utah and Indiana.
ENVIRONMENTAL FATE
1,1,1-Trichloroethane has a high Henry's Law con-
stant (8X10-3 atm-cu m/mole(4)) and will volatilize rap-
idly from water and soil with diffusion through the liquid
phase controlling volatilization from water. Half-life for
evaporation from water obtained from laboratory sys-
tems range from a fraction of an hour to several hours.
Various estimates of volatilization half-lives range from
5.1-10.6 days for ponds, 3-29 hr for rivers, and 3.8-12
days for lakes.
The adsorption of 1,1,1-trichloroethane to soil is pro-
portional to the organic carbon content of the soil(4-6).
The mineral content of the soil is not a contributing
factor(5). 1,1,1-Trichloroethane is adsorbed strongly to
peat moss, less strongly to clay, very slightly to dolomite
limestone and not at all to sand(2). It has a low adsorption
to silt loam (Koc = 183)(3). From the fact that it is not
retained in the soil during bank infiltration, and that it is
frequently found in groundwater in high concentrations,
one can safely conclude that it is not adsorbed strongly
by soils, especially subsurface soils(1). Based upon
experimental measurement, the mean Koc range of
1,1,1-trichloroethane in a silty clay soil and sandy loam
soilis81-89(8,SRC).
There is no or very slow degradation in soils. No
degradation has been observed in subsurface soils in 27
weeks. However in loamy sand, slow degradation has
been observed under acclimated conditions. Slow deg-
radation may occur in water under anaerobic or aerated
conditions; degradation may take several weeks and
acclimation is important. No degradation in river water
has been found. 1,1,1-Trichloroethane degraded to vi-
nylidene chloride as a first step in its biotransformation in
microcosms containing aquifer water and sediment col-
lected from uncontaminated sites in the Everglades.
Considerable degradation occurred within two weeks.
Field evidence of biodegradation in aquifers indicates a
half-life of 231 days.
1,1,1-Trichloroethane has been shown to undergo
biotransformation by a reductive dechlorination to 1,1-
dichloroethane and chloroethane under methanogenic
conditions. Laboratory reactors have demonstrated that
1,1,1-trichloroethane can be biodegraded under anaero-
bic simulations; it was suggested that in-situ anaerobic
biodegrdation may be a viable alternative for clean-up for
various contaminated soil and groundwater sites.
Hydrolysis is not a significant degradation process
having a half-life of approximately 6 months. The product
of hydrolysis is vinylidene chloride. Direct photolysis is
not important in the troposphere, but is in the strato-
sphere, and leads to the chemical's rapid degradation.
Photodegradation is not observed in water.
The BCF in bluegill sunfish in a 28 day test was 8.9.
This indicates that 1,1,1-trichloroethane has little ten-
dency to bioconcentrate in fish. Although the amount of
experimental data for 1,1,1-trichloroethane is limited,
confidence in this result is increased because values of
BCFs in related compounds are similar.
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; 551
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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