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Basic Information about Hexachlorobenzene in Drinking Water

Hexachlorobenzene at a Glance

Maximum Contaminant Level (MCL) = 0.001 milligrams per Liter (mg/L) or 1 part per billion (ppb)

Maximum Contaminant Level Goal (MCLG) = zero

Health Effects
Some people who drink water containing hexachlorobenzene in excess of the MCL over many years could experience liver or kidney problems; reproductive difficulties; increased risk of cancer.

Drinking Water Heaith Advisories provide more information on health effects

Chemical Abstract Service Registry Number
118-74-1

Sources of Contamlnation
Discharge from metal refineries and agricultural chemical factories

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

EPA regulates hexachlorobenzene in drinking water to protect public health. Hexachlorobenzene 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 hexachlorobenzene?
Hexachlorobenzene, a synthetic organic chemical, is a white crystalline solid. It does not occur naturally in the environment.

Uses for hexachlorobenzene.
Currently there are no commercial uses of hexachlorobenzene in the United States. It was used as a fungicide and to make fireworks and ammunition.

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

What are hexachlorobenzene's health effects?
Some people who drink water containing hexachlorobenzene well in excess of the maximum contaminant level (MCL) for many years could experience liver or kidney problems; reproductive difficulties; increased risk of cancer.

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

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What are EPA's drinking water regulations for hexachlorobenzene?
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 hexachlorobenzene is zero. 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 hexachlorobenzene, called a maximum contaminant level (MCL), at 0.001 mg/L or 1 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.

The Phase V Rule, the regulation for hexachlorobenzene, 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 hexachlorobenzene as part of the Six Year Review and determined that the zero MCLG and 0.001 mg/L or 1 ppb MCL for hexachlorobenzene are still protective of human health.

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

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How does hexachlorobenzene get into my drinking water?
Although it is not currently used commercially in the United States, hexachlorobenzene was widely used as a pesticide until 1965. It was also used in the production of rubber and wood preservatives. It breaks down very slowly and still persists in the environment. Small particles stick to soil and remain in sediments in the bottoms of water bodies; it accumulates in plants, grasses, fish, marine animals, birds and animals.

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 hexachlorobenzene is in my drinking water?
When routine monitoring indicates that hexachlorobenzene levels are above the MCL, your water supplier must take steps to reduce the amount of hexachlorobenzene 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 hexachlorobenzene be removed from my drinking water?
The following treatment method(s) have proven to be effective for removing hexachlorobenzene to below 0.001 mg/L or 1 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.

The CCR summarizes information regarding sources used (i.e., rivers, lakes, reservoirs, or aquifers), any detected contaminants, compliance and educational information.

Some water suppliers have posted their annual reports on EPA's Web site.

Other EPA Web sites

Other Federal Departments and Agencies

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