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Community Water

Arsenic and Your Health

Arsenic is a toxic chemical element that is naturally found in the Earth's crust in soil, rocks, and minerals. The levels of arsenic found in drinking water systems and private water supplies across the United States vary widely.

Arsenic occurs naturally in the environment and as a by-product of some agricultural and industrial activities. It can enter drinking water through the ground or as run-off into surface water sources.

Some people who drink water containing arsenic in excess of the U.S. Environmental Protection Agency's (EPA) standard over many years could experience skin damage or problems with their circulatory system and may have an increased risk of developing cancer.

In 2001 EPA reduced the regulatory drinking water standard called the Maximum Contaminant Level (MCL) from 50 micrograms per liter (µg/L) to 10 micrograms per liter (µg/L). This decision was based on bladder and lung cancer risks (EPA 2001a). Lowering the MCL reduces bladder and lung cancer mortality and morbidity by 37 to 56 cancers a year in the United States (EPA 2001b).

Exposure and Risk

The majority of health risks of arsenic exposure in the United States are long term. Although short-term exposures to high doses cause adverse effects in people, such exposures do not occur from U.S. Environmental Protection Agency (EPA)-regulated public water supplies in the United States that comply with the arsenic Maximum Contaminant Level. A high dose is about a thousand times higher than the drinking water standard.

Some people who drink water containing arsenic in excess of EPA's standard over many years could experience health effects, including:

  • thickening and discoloration of the skin;
  • stomach pain;
  • nausea;
  • vomiting;
  • diarrhea;
  • liver effects;
  • cardiovascular effects;
  • pulmonary effects;
  • immunological effects;
  • neurological effects, such as numbness and partial paralysis;
  • reproductive effects;
  • endocrine effects, such as diabetes; and
  • cancer
    • bladder
    • lungs
    • skin
    • kidney
    • nasal passages
    • liver
    • prostate.
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If your water comes from a municipal or privately-owned water company that meets the definition of a community water system, they are already testing for arsenic in your water.

If you have your own household water supply, you are responsible for maintaining and testing it. Contact your local health department to find out whether arsenic is a contaminant of concern in your area. Your state's drinking water agency can give you names of laboratories that are certified to test drinking water.

Find certified home treatment units on the following Web sites:

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