Water quality fact sheet: Nitrate

The primary health concern regarding nitrate and nitrite is the formation of methaemoglobinaemia, so- called ‘blue-baby syndrome’. Nitrate is reduced to nitrite in the stomach of infants, and nitrite is able to oxidize haemoglobin (Hb) to methaemoglobin (metHb), which is unable to transport oxygen around the body. This reduced oxygen transport becomes clinically manifest when metHb concentrations reach 10% or more of normal Hb concentrations; the condition, called methaemo- globinaemia, causes cyanosis and, at higher concentrations, asphyxia.