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Community Water

Nitrate and Your Health

Nitrate and nitrite are nitrogen-oxygen molecules that can combine with various organic and inorganic compounds. Nitrate is the form commonly found in water, often in areas where nitrogen-based fertilizers are used. The greatest use of nitrate is as a fertilizer. Vegetables, food, and meat are the major sources of nitrate exposure.

Nitrate and nitrite originate in drinking water from nitrate-containing fertilizers, sewage and septic tanks, and decaying natural material such as animal waste. Nitrate is very soluble in water, can easily travel, and does not bind to soils. Nitrate and nitrite are likely to remain in water until consumed by plants or other organisms.

The U.S. Environmental Protection Agency (EPA) set levels of 10 mg/L for total nitrate and nitrite, 10 mg/L nitrate, and 1 mg/L nitrite as drinking water standards. Infants under the age of 6 months who drink water containing more than 1 mg/L nitrite, or 10 mg/L nitrate, could become seriously ill and, if untreated, may die. In the body, nitrate converts to nitrite. Nitrite interferes with the oxygen-carrying capacity of blood. Symptoms, such as shortness of breath and blueness of the skin, can occur rapidly over a period of days.

Exposure and Risk

The risks of excessive levels of nitrate apply to infants.

  • Short-term: Excessive levels of nitrate in drinking water have caused serious illness and sometimes death. The serious illness in infants is due to the conversion of nitrate to nitrite by the body, which can interfere with the oxygen-carrying capacity of the child's blood. This can be an acute condition in which health gets worse rapidly over a period of days. Symptoms include shortness of breath and blueness of the skin.
  • Long-term: Researchers continue to explore if there are associations with long-term exposures to nitrate, including adverse reproductive effects and some cancers. The studies are not conclusive at this time, and health standards are focused on protecting infants.
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Nitrate is monitored once a year during the quarter that previously had the highest nitrate result. If a water system's samples are less than 0.5 mg/L nitrite, the state specifies the frequency of additional monitoring. Initially, a water system samples quarterly for at least a year.

The following treatment methods have been approved by the EPA for removing nitrate/nitrite:

  • ion exchange,
  • reverse osmosis, and
  • electrodialysis.

If the levels of nitrate/nitrite exceed their Maximum Contaminant Levels, 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.

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