Nitrite

Nitrite

Nitrite is a negatively charged ion (anion) of one nitrogen and two oxygen atoms. Nitrites are widely used throughout the chemical and pharmaceutical industries. Nitrites are used to create pre-cursors for dyes and are used in the rubber industry. Sodium nitrite is an effective corrosion inhibitor and is an effective drug for the treatment of cyanide poisoning.

Sodium nitrite is used in the curing of meat as it prevents bacterial growth and is highly effective at inhibiting the germination of endospores of the C. Botulinum thus preventing botulism. Nitrites react with the meat to give a pink-red “fresh” colour which is desirable to the meat industry.

In contrast to the nitrate ion, the nitrite ion is an unstable oxidation state and is therefore far less abundant in the environment. Certain bacteria found in the environment and within the human body can convert nitrate ions to the more reactive nitrite molecule.

Agency Limit (ppm)
UK - DEFRA 0.5
US - EPA 1.0
EU - EEA 0.5
WHO 0.3

Nitrite and our health

Ingested nitrites may be absorbed directly from both the stomach and the small intestine. Absorbed nitrite is involved with the oxidation of haemoglobin, it binds tightly to the iron atom at the heart of the haemoglobin molecule thus preventing it from fulfilling its function as an oxygen transporter in the blood. The deactivation of haemoglobin leads to a blue or purple tinge to the skin, called cyanosis. Babies are far more susceptible to nitrite poisoning where the cyanosis is termed blue baby syndrome.

Nitrites have been classified as probable carcinogens. Nitrites are known to react with amines present in meat to form nitrosamines, these nitrosamines can damage DNA leading to cancers.

Nitrite in our drinking water

As nitrite is a reactive species its concentration in drinking water is normally low (below 1ppm) but can reach higher level where high concentrations of nitrate are found. Elevated levels of nitrate and consequently nitrite may be caused by agricultural run-off.

In the UK drinking water companies may choose to disinfect water either by the addition of chlorine or chloramine. The addition of chloramine to water may give rise to the formation of nitrite within the distribution system. The nitrification effect within water distribution systems can increase nitrite levels by 0.2 - 1.5 ppm but potentially by over 3ppm

Tests

Nitrite in your drinking water can be detected by the following tests.

Removing Nitrite

Nitrite can be reduced or removed from your drinking water using the following methods.

  • Reverse Osmosis
  • Anion Exchange Columns
  • Activated Carbon Filters

Further reading