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Environmental Safety Limits of Nitrates

Nitrates (NO3) are composed of nitrogen and oxygen that combine with other molecules. Nitrates are converted to nitrites (NO2) when they are ingested. Nitrates can cause health problems in humans and are particularly dangerous for infants. The U.S. Environmental Protection Agency (EPA) has set standards for the amount of nitrates allowed in drinking water.

  1. Health Effects

    • According to the EPA, nitrates in drinking water pose a health hazard to infants under six months of age. Ingestion of nitrates at greater than the maximum contaminant level can cause serious and sometime fatal illness in babies. Among the symptoms a baby with nitrate poisoning would exhibit are shortness of breath and blue baby syndrome.

    Sources

    • The Centers for Disease Control (CDC) states that nitrates are most often found in ground water and surface water. They come from nitrogen-containing fertilizers and animal and human wastes. Nitrates in the soil are soluble and so end up in water sources. Nitrates occur naturally in foods such as cauliflower, spinach, collard greens, broccoli, and root vegetables. Sodium nitrate is a preservative used in meats and meat products. About 6 percent of nitrates consumed come from this preservative. Another source is medications, including antimalarial and antidiarrheal concoctions. Most nitrates consumed by infants come from the water mixed in with powdered formula.

    Occurrence

    • Excessive amounts of nitrates occur most often in shallow, rural wells in areas where nitrogen containing fertilizers are common. Water can also be contaminated with nitrates by leaky septic systems.

    EPA Regulations

    • The 1974 Safe Drinking Act set standards for the amount of nitrates in drinking water. The standards for this and other water contaminants are based on possible health risks that could occur over a lifetime of exposure. The standards are called maximum contaminant level goals (MCLG). The MCLG for nitrates in drinking water is 10 mg per liter or 10 parts per million. Individual states may set stricter limits.

    Your Water Supply

    • If your water comes from a municipal source, your water supplier is required to monitor nitrate levels. If the level exceeds the MCLG, your water supplier is required to notify you within 24 hours, take steps to reduce the nitrate level, and provide an alternative water source if necessary. In addition, your water supplier is required to provide customers with a water quality report each year. If you get your water from your own well, contact your health department or local water system for information on water contaminants in your area.

    Removing Nitrates

    • Nitrates can be removed from water by ion exchange, reverse osmosis, and electrodialysis.

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