Nitrosamine

Overview
Nitrosamines are chemical compounds of the chemical structure R1N(-R2)-N=O, some of which are carcinogenic.

Occurrence in food
Nitrosamines are produced from nitrites and secondary amines, which often occur in the form of proteins. Their formation can occur only under certain conditions, including strongly acidic conditions such as that of the human stomach. High temperatures, as in frying, can also enhance the formation of nitrosamines.

The nitrite forms nitrous acid (HNO2), which splits into the nitrosonium cation, N=O+, and the hydroxide anion, OH−. The nitrosonium cation then reacts with an amine to produce nitrosamine.

Nitrosamines are found in many foodstuffs especially beer, fish, fish byproducts, and in meat and cheese products preserved with nitrite pickling salt. The US government established limits on the amount of nitrites used in meat products to decrease cancer risk in the population. There are also rules about adding ascorbic acid or related compounds to meat, because they inhibit nitrosamine formation.

Occurrence in other consumer products
Nitrosamines can be found in tobacco smoke and latex products. A test of party balloons and condoms indicated that many of them release small amounts of nitrosamines. However, nitrosamines from condoms are not expected to be of toxicological significance.

Cancer
Nitrosamines can cause cancers in a wide variety of animal species, a feature which suggests that they may also be carcinogenic in humans. Epidemiological data suggests that nitrosamines in preserved food cause stomach cancer.

Uses

 * Rubber products
 * Pesticides
 * Certain cosmetics

Tobacco-specific nitrosamines

 * N-Nitrosonornicotine (NNN)
 * NNK
 * NNAL
 * NAT
 * NAB
 * iso-NNAL
 * iso-NNAC

Other nitrosamines

 * NDEA
 * NDMA