Nitrate
Nitrate compounds (eg sodium nitrate) are found naturally on earth as large deposits. Nitrate (NO3−) naturally results from the breakdown of animal (or human) waste, but nitrate in groundwater mainly comes from fertilizers (eg ammonium nitrate) used in agriculture. Nitrate is much less toxic than ammonia. Nitrate is naturally consumed by growing plants, including fruit trees. Particularly vegetables may contain high levels of nitrate due to (besides nitrate fertilization) reduced sunlight exposure, undersupply of molybdenum and iron, and/or reduced assimilation of nitrate in the plant.
Nitrite (NO2−)
Methemoglobinemia
Methemoglobinemia is characterized by elevated levels of oxidized (Fe3+) hemoglobin (= methemoglobin = metHb) relative to (Fe2+) haemoglobin levels in the blood. Infants are particularly vulnerable to methemoglobinemia due to nitrate metabolizing triglycerides present at higher concentrations than at other stages of development.
