NITRATE

Fertilizers and animal manure, septic/municipal wastewater, natural soils/rocks; added to cured meats; naturally high in leafy vegetables [1][2][4].

Private well water in agricultural areas; some public water supplies; foods (leafy vegetables, processed meats); infant formula mixed with contaminated water [1][2][5].

In the body, nitrate can become nitrite, which reduces blood’s oxygen-carrying ability, causing “blue baby” syndrome (methemoglobinemia) in infants; long-term high intake has been linked to pregnancy and thyroid effects; under conditions that form N‑nitroso compounds, nitrate/nitrite are probably carcinogenic (IARC Group 2A) [1][3][4].

Infants under 6 months, pregnant people, those with certain enzyme deficiencies or anemia, and private well users near agriculture [1][2][5].

Test private wells yearly; if above EPA limit (10 mg/L as nitrate‑N), use certified treatment (reverse osmosis, ion exchange, distillation) or alternative safe water—do not boil; maintain septic systems; limit processed meats [2][4][5][1].