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Water: Basic Information about Regulated Drinking Water Contaminants

Basic Information about Endrin in Drinking Water

Endrin at a Glance

Maximum Contaminant Level (MCL) = 0.002 milligrams per Liter (mg/L) or 2 parts per billion (ppb)

Maximum Contaminant Level Goal (MCLG) = 0.002 mg/L or 2 ppb

Health Effects
Some peopte who drink water containing endrin in excess of the MCL over many years could experience liver problems.

Drinking Water Health Advisories provide more information on health effects

Chemical Abstract Service Registry Number

Sources of Contamination
Residue of banned insecticide

List of all Regulated Contaminants (PDF) (6 pp, 396 K, About PDF)

EPA regulates endrin in drinking water to protect public health. Endrin may cause health problems if present in public or private water supplies in amounts greater than the drinking water standard set by EPA.

What is endrin?
Endrin is an organic solid of odorless white crystals.

Uses for endrin.
Endrin is an insecticide which has been used mainly on field crops such as cotton, maize, sugarcane, rice, cereals, ornamentals, and other crops. It has also been used for grasshoppers in non-cropland and to control voles and mice in orchards. Once widely used in the United States, most uses were cancelled in 1980.

If you are concerned about endrin in a private well, please visit:

What are endrin's health effects?
Some people who drink water containing endrin well in excess of the maximum contaminant level (MCL) for many years could experience liver problems.

This health effects language is not intended to catalog all possible health effects for endrin. Rather, it is intended to inform consumers of some of the possible health effects associated with endrin in drinking water when the rule was finalized.

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What are EPA's drinking water regulations for endrin?
In 1974, Congress passed the Safe Drinking Water Act. This law requires EPA to determine the level of contaminants in drinking water at which no adverse health effects are likely to occur. These non-enforceable health goals, based solely on possible health risks and exposure over a lifetime with an adequate margin of safety, are called maximum contaminant level goals (MCLG). Contaminants are any physical, chemical, biological or radiological substances or matter in water.

The MCLG for endrin is 0.002 mg/L or 2 ppb. EPA has set this level of protection based on the best available science to prevent potential health problems. EPA has set an enforceable regulation for endrin, called a maximum contaminant level (MCL), at 0.002 mg/L or 2 ppb. MCLs are set as close to the health goals as possible, considering cost, benefits and the ability of public water systems to detect and remove contaminants using suitable treatment technologies. In this case, the MCL equals the MCLG, because analytical methods or treatment technology do not pose any limitation.

The Phase V Rule, the regulation for endrin, became effective in 1994. The Safe Drinking Water Act requires EPA to periodically review the national primary drinking water regulation for each contaminant and revise the regulation, if appropriate. EPA reviewed endrin as part of the Six Year Review and determined that the 0.002 mg/L or 2 ppb MCLG and 0.002 mg/L or 2 ppb MCL for endrin are still protective of human health.

States may set more stringent drinking water MCLGs and MCLs for endrin than EPA.

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How does endrin get into my drinking water?
The major source of endrin in drinking water is residue of banned insecticide.

A federal law called the Emergency Planning and Community Right to Know Act (EPCRA) requires facilities in certain industries, which manufacture, process, or use significant amounts of toxic chemicals, to report annually on their releases of these chemicals. For more information on the uses and releases of chemicals in your state, contact the Community Right-to-Know Hotline: (800) 424-9346.

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How will I know if endrin is in my drinking water?
When routine monitoring indicates that endrin levels are above the MCL, your water supplier must take steps to reduce the amount of endrin so that it is below that level. Water suppliers must notify their customers as soon as practical, but no later than 30 days after the system learns of the violation. Additional actions, such as providing alternative drinking water supplies, may be required to prevent serious risks to public health.

If your water comes from a household well, check with your health department or local water systems that use ground water for information on contaminants of concern in your area.

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How will endrin be removed from my drinking water?
The following treatment method(s) have proven to be effective for removing endrin to below 0.002 mg/L or 2 ppb: granular activated carbon.

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How do I learn more about my drinking water?
EPA strongly encourages people to learn more about their drinking water, and to support local efforts to protect the supply of safe drinking water and upgrade the community water system. Your water bill or telephone book's government listings are a good starting point for local information.

Contact your water utility. EPA requires all community water systems to prepare and deliver an annual consumer confidence report (CCR) (sometimes called a water quality report) for their customers by July 1 of each year. If your water provider is not a community water system, or if you have a private water supply, request a copy from a nearby community water system.

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