Dionex Corporation Home

Nitrates and Sulfates

Nitrates are toxic compounds that can pose serious risks to human health and the environment. Exposure to high levels of nitrates may cause serious illness or death, as well as significant environmental damage to streams, lakes, and rivers. Infants and children are especially sensitive to elevated levels of nitrates, which cause methemoglobinemia, or "blue-baby syndrome." When too much nitrate is ingested, it reduces the capacity of blood to carry oxygen, turning the skin blue, causing shortness of breath, and depriving the brain of oxygen. Under the authority of the Safe Drinking Water Act (1974), the EPA has set a maximum contaminant level for public water supplies of 10 mg/L, which is equal to 10 ppm for nitrogen in the nitrate form.

Sulfate occurs naturally in drinking water, and has been a cause for concern due to reports that diarrhea may be associated with the ingestion of water containing high levels of sulfate. Sulfate in drinking water currently has a secondary maximum contaminant level of 250 mg/L based on aesthetic effects (i.e., taste and odor). This regulation is not a federally enforceable standard, but is provided as a guideline for States and public water systems. The EPA estimates that about 3% of the public drinking water systems in the country may have sulfate levels of 250 mg/L or greater.