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Consumer Factsheet on: METHOXYCHLOR
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 Methoxychlor and how is it used?
Methoxychlor is a colorless organic solid with a slightly fruity odor. It is an insecticide preferred
to DDT for use on animals, in animal feed, and on DDT-sensitive crops such as squash, melons,
etc. Since methoxychlor is more unstable than DDT, it has less residual effect. It has been used
extensively in Canada for the control of biting flies, and is also effective against mosquitoes and
houseflies.
The list of trade names given below may help you find out whether you are using this chemical at
home or work.
Trade Names and Synonyms:
Dimethoxy-DDT
Methoxy-DDT
Chemform
Maralate
Methoxo
Methoxcide
Metox
Moxie
Why is Methoxychlor 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 methoxychlor has been set at 40 parts per billion (ppb) 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 40 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 methoxychlor to potentially cause the following health effects when
people are exposed to it at levels above the MCL for relatively short periods of time: central
nervous system depression, diarrhea, and damage to liver, kidney and heart tissue.
Long-term: Methoxychlor has the potential to cause the following effects from a lifetime exposure
at levels above the MCL: damage to liver, kidney and heart tissue; retards growth.
How much Methoxychlor is produced and released to the environment?
Production of methoxychlor has decreased: from 3.7 million lbs. in 1978 to 700,000 lbs in 1982.
Release of methoxychlor to the environment occurs due to its use as an insecticide and from
losses during the manufacture, formulation, packaging, and disposal of methoxychlor.
From 1987 to 1993, according to EPA's Toxic Chemical Release Inventory, methoxychlor
releases to land and water totalled only about 2000 lbs.
What happens to Methoxychlor when it is released to the environment?
Methoxychlor does not tend to persist when released to soil or water. If released to soil,
methoxychlor will adhere to soils, though some may leach into groundwater as suggested by the
detection of methoxychlor in some groundwater samples. It is broken down by soil and sediment
microbes under some conditions. In water, methoxychlor degrades quite rapidly - within days
compared to months as in soil. It may accumulate in some shellfish, but not in fish.
How will Methoxychlor be Detected in and Removed from My Drinking Water?
The regulation for methoxychlor became effective in 1992. 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 methoxychlor is present above 0.1 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 methoxychlor so that it is consistently below that level. The
following treatment methods have been approved by EPA for removing methoxychlor: Granular
activated charcoal.
How will I know if Methoxychlor is in my drinking water?
If the levels of methoxychlor exceed the MCL, 40 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: 40 ppbMcl: 40 ppb 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
book's 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: EPA's
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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