Consumer Factsheet on: DICHLOROMETHANE
List of Contaminants
As part of the Drinking Water and Health pages, this fact
sheet is part of a larger publication:
National Primary Drinking Water Regulations
This is a factsheet about a chemical that may be found in some
public or private drinking water supplies. It may cause health
problems if found in amounts greater than the health standard set
by the United States Environmental Protection Agency (EPA).
What is DCM and how is it used?
Dichloromethane (DCM) is a colorless organic liquid with a sweet,
chloroform-like odor. The greatest use of DCM is as a paint
remover. Other uses include: solvent and cleaning agent in a
variety of industries, a fumigant for strawberries and grains; and
to extract substances from foodstuffs.
The list of synonyms given below may help you find out whether you
are using this chemical at home or work.
Trade Names and Synonyms:
DCM
Methylene chloride
Why is DCM being Regulated?
In 1974, Congress passed the Safe Drinking Water Act. This law
requires EPA to determine safe levels of chemicals in drinking
water which do or may cause health problems. These non-enforceable
levels, based solely on possible health risks and exposure, are
called Maximum Contaminant Level Goals.
The MCLG for dichloromethane has been set at zero because EPA
believes this level of protection would not cause any of the
potential health problems described below.
Based on this MCLG, EPA has set an enforceable standard called a
Maximum Contaminant Level (MCL). MCLs are set as close to the MCLGs
as possible, considering the ability of public water systems to
detect and remove contaminants using suitable treatment
technologies.
The MCL has been set at 5 parts per billion (ppb) because EPA
believes, given present technology and resources, this is the
lowest level to which water systems can reasonably be required to
remove this contaminant should it occur in drinking water.
These drinking water standards and the regulations for ensuring
these standards are met, are called National Primary Drinking Water
Regulations. All public water supplies must abide by these
regulations.
What are the Health Effects?
Short-term: EPA has found dichloromethane to potentially cause the
following health effects when people are exposed to it at levels
above the MCL for relatively short periods of time: Damage to the
nervous system and to blood.
Long-term: Dichloromethane has the potential to cause the following
effects from a lifetime exposure at levels above the MCL: liver
damage; cancer.
How much DCM is produced and released to the environment?
Production of DCM has been decreasing: from a high of 561 million
lbs. in 1986, to roughly 410 million lbs. in 1993. It is released
in wastewater primarily from the following industries: Paint and
ink, aluminum forming, coal mining, photographic equipment and
supplies, pharmaceutical, organic chemical/plastics, metal
foundries and laundries. DCM is also formed during the chlorination
of water.
From 1987 to 1993, according to EPA's Toxic Chemical Release
Inventory, DCM releases to land and water totalled over 2.1 million
lbs. These releases were primarily from medicinals and botanicals
industries. The largest releases occurred in Connecticut and New
York.
What happens to DCM when it is released to the environment?
Most DCM is released to air where it is degraded by sunlight within
a few months. Releases to water evaporate very quickly. It will
evaporate from soil but can also leach through soil to ground
water. DCM is not likely to accumulate in aquatic life.
How will DCM be Detected in and Removed from My Drinking Water?
The regulation for dichloromethane became effective in 1994.
Between 1993 and 1995, EPA required your water supplier to collect
water samples every 3 months for one year and analyze them to find
out if dichloromethane is present above 0.5 ppb. If it is present
above this level, the system must continue to monitor this
contaminant.
If contaminant levels are found to be consistently above the MCL,
your water supplier must take steps to reduce the amount of
dichloromethane so that it is consistently below that level. The
following treatment methods have been approved by EPA for removing
dichloromethane: Granular activated charcoal in combination with
Packed Tower Aeration.
How will I know if DCM is in my drinking water?
If the levels of dichloromethane exceed the MCL, 5 ppb, the system
must notify the public via newspapers, radio, TV and other means.
Additional actions, such as providing alternative drinking water
supplies, may be required to prevent serious risks to public
health.
Drinking Water Standards:
Mclg: zero
Mcl: 5 ppb
DCM Releases to Water and Land, 1987 to 1993 (in pounds):
| Water | Land |
TOTALS (in pounds) | 1,544,694 | 556,830 |
Top Ten States* |
---|
CT | 940,158 | 0
|
NY | 58,400 | 155,755
|
GA | 166,700 | 0
|
NJ | 138,302 | 2,721
|
WI | 0 | 139,920
|
SC | 20,860 | 52,810
|
MI | 39,575 | 32,900
|
KS | 0 | 33,489
|
MO | 0 | 27,295
|
TX | 15,910 | 823
|
Major Industries* |
---|
Medicinals, botanicals | 1,106,858 | 0
|
Photographic supplies | 58,400 | 155,755
|
Misc Indust. organics | 141,942 | 53,741
|
Custom plastics, resins | 0 | 139,920
|
Pharmaceuticals | 37,575 | 0
|
Potato/corn chips&snacks | 2,000 | 32,900
|
Air conditioning/heating | 0 | 33,489
|
Steel pipe, tubing | 0 | 27,295
|
* Water/Land totals only include facilities with releases greater
than a certain amount - usually 1000 to 10,000 lbs.
Learn more about your drinking water!
EPA strongly encourages people to learn more about their drinking
water, and to support local efforts to protect and upgrade the
supply of safe drinking water. Your water bill or telephone books
government listings are a good starting point.
Your local water supplier can give you a list of the chemicals they
test for in your water, as well as how your water is treated.
Your state Department of Health/Environment is also a valuable
source of information.
For help in locating these agencies or for information on drinking
water in general, call: EPAs Safe Drinking Water Hotline: (800)
426-4791.
For additional information on the uses and releases of chemicals in
your state, contact the: Community Right-to-Know Hotline: (800) 424-9346.
List of Contaminants
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