United States
Environmental Protection
Ag :ncy
&EPA
Office of Water
4601
EPA811-F-95-004J-T
October 1 995
National Primary Drinking
Water Regulations
Dichloromethane
CHEMICAL/ PHYSICAL PROPERTIES
CAS NUMBER: 75-09-2
COLOR/ FORM/ODOR:
A colorless liquid with a sweet,
pleasant odor like chloroform.
M.P.: N/A B.P.: 39.75° C
VAPOR PRESSURE: 400 mm Hg at 24.1° C
OCTANOL/WATER PARTITION (Kow):
Log Kow = 1.25
DENSITY/SPEC. GRAV.:
SOLUBILITY: N/A
N/A
SOIL SORPTION COEFFICIENT:
Log Koc estimated at 1.68; High to
moderate mobility in soil
ODOR/TASTE THRESHOLDS: N/A
BlOCONCENTRATION FACTOR:
BCF = 5 (est.); not expected to biocon-
centrate in aquatic organisms.
HENRY'S LAW COEFFICIENT:
N/A; Reportedly high. Moderate
evaporation from water.
TRADE NAMES/SYNONYMS:
DCM, Methylene chloride
DRINKING WATER STANDARDS
MCLG: zero
MCL: 0.005 mg/L
HAL(child): 1 day: 10 mg/L
10-day: 2 mg/L
HEALTH EFFECTS SUMMARY
Acute: EPA has found dichloromethane to potentially
cause the following health effects from acute exposures
at levels above the MCL: neurological (encephalosis)
and blood cell damage.
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 to 10 mg/
L or a ten-day exposure to 2 mg/L.
Chronic: Dichloromethane has the potential to cause
the following health effects from long-term exposures at
levels above the MCL: liver damage
Cancer: There is some evidence that dichlorometh-
ane may have the potential to cause cancer from a
lifetime exposure at levels above the MCL.
USAGE PATTERNS
Production of DCM has been decreasing: from a high
of 561 million Ibs. in 1986, to 410 million Ibs in 1993
(projected 1993 data). In 1988, industries consumed
)CM for various uses as follows: paint stripper, 28%;
aerosols, 18%; exports, 15%; chemical processing, 11%;
urethane foam blowing agent, 9%; metal degreasing,
8%; electronics, 7%; other, 4%.
The greatest use of DCM is as a paint remover. Other
uses include: solvent and cleaning agent in chemical
manufacture, textiles, electronics, metals and plastics,
pesticides industries; blowing and cleaning agent in the
urethane foam industry; fumigant for strawberries and
grains, and as degreener for citrus fruits; in pharmaceu-
Toxic RELEASE INVENTORY -
RELEASES TO WATER AND LAND:
1987 TO 1993
TOTALS (in pounds)
Top Ten States*
CT
NY
GA
NJ
Wl
SC
Ml
KS
MO
TX
Water
1,544,694
940,158
58,400
166,700
138,302
0
20,860
39,575
0
0
15,910
Major Industries*
Medicinals, botanicals 1,106,858
Photographic supplies 58,400
Misc Indust. organics 141,942
Custom plastics, resins 0
Pharmaceuticals 37,575
Potato/corn chips&snacks 2,000
Air conditioning/heating 0
Steel pipe, tubing 0
Land
556,830
0
155,755
0
2,721
139,920
52,810
32,900
33,489
27,295
823
0
155,755
53,741
139,920
0
32,900
33,489
27,295
* Water/Land totals only include facilities with releases
greater than a certain amount - usually 1000 to 10,000 Ibs.
October 1995
Technical Version
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ticals and as an anesthetic; in extraction of caffeine,
cocoa, fats, spices and beer hops; as a heat transfer
agent in refrigeration products.
RELEASE PATTERNS
Dichloromethane is released to the air from its use as
an aerosol propellant, paint remover, metal degreaser
and a urethane foam blowing agent. It is released in
wastewater primarily from the following industries: Paint
and ink, aluminum forming, coal mining, photographic
equipment and supplies, pharmaceutical, organic chemi-
cal/plastics, rubber processing, foundries and laundries.
In a 1978 report, release of dichloromethane to the
land totalled 61.6 million Ibs, with a breakdown for its
various uses as follows: production, 22,000 Ibs; paint
removers, 19.4 million Ibs.; metal degreasing, 13.4 mil-
lion Ibs; aerosols, 8.4 million Ibs.; foam blowing agent, 2.6
million Ibs.; pharmaceutical solvent, 4.8 million Ibs.; mis-
cellaneous solvent uses, 13 million Ibs. Release of di-
chloromethane to water totalled 8.1 million Ibs., with
breakdown: production, 66,000 to 132,000 Ibs.; paint
removers, 3.1 million Ibs.; metal degreasing, 2.2 million
Ibs.; pharmaceutical solvent, 1 million Ibs.; miscella-
neous solvent uses, 1.7 million Ibs.
Dichloromethane is also formed during the chlorina-
tion of water.
From 1987 to 1993, according to EPA's Toxic Chemi-
cal Release Inventory, DCM releases to land and water
totalled over 2.1 million Ibs., of which about 75 % percent
was to water. These releases were primarily from medici-
nals and botanicals industries which use DCM as a
solvent and extractive. The largest releases occurred in
Connecticut and New York.
ENVIRONMENTAL FATE
Most of the dichloromethane will be released to the
atmosphere where it will degrade by reaction with photo-
chemically produced hydroxyl radicals with a half-life of
a few months. It will be subject to direct photolysis.
Releases to water will primarily be removed by evapo-
ration. Half-lives for the evaporation from water of 3-5.6
hours have been determined at moderate mixing condi-
tions. When released into a river, dichloromethane levels
were non-detectable 3-15 miles from the source. Biodeg-
radation is possible in natural waters but will probably be
very slow compared with evaporation. Dichloromethane
is reported to completely biodegrade under aerobic con-
ditions with sewage seed or activated sludge between 6
hours to 7 days. It will not be expected to significantly
adsorb to sediment. Hydrolysis is not an important pro-
cess under normal environmental conditions, with a
minimum reported half-life for hydrolysis of approxi-
mately 18 months.
Releases to soil will evaporate rapidly from near-
surface soil and partially leach into groundwater where its
fate is unknown. Little work has been done on the
adsorption of dichloromethane to soil. It is adsorbed
strongly to peat moss, less strongly to clay, only slightly
to dolomite limestone, and not at all to sand. A log Koc of
1.68 can be calculated from a reported log Kom of 1.44.
Although experimental data are lacking, dichlorometh-
ane would not be expected to bioconcentrate due to its
low octanol/water partition coefficient (log Kow is 1.25),
from which an estimated BCF of 5 can be estimated using
recommended regression equation.
The major route of human exposure is from air, which
can be high near sources of emission, and contaminated
drinking water.
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:
4 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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