Nitrate and nitrite are naturally occurring ions that are part of the nitrogen cycle. Nitrate is commonly used in inorganic fertilisers and nitrite in the form of sodium nitrite in food preservation. The health implications to humans of both are due to excessive consumption of nitrite – and nitrates reduction to nitrite. 

WHO Limits: 

• Nitrate - 50 mg/l
• Nitrite - 3 mg/l

Symptoms of Nitrite (and the reduction of ntirate to nitrite) Contamination: 

• Methaemoglobinaemia (blood disorder where too little oxygen is delivered to cells)
• Cyanosis (bluish discolouration to hands and feet due to too little oxygen)
• Asphyxia (suffocation)
• Blue-baby syndrome in infants

Treatment Methods: 

• Ion exchange 

For Further Information:

WHO Water Quality Guidelines - 4th Edition

WHO Nitrate and Nitrite in Drinking Water