Exposure to N-nitrosamines

Excluding tobacco and tobacco smoke (lf f3), the largest known human exposure to N-nitrosamines is in the industrial sector (4). The area or process air samples containing the largest amount of nitrosamines are in a tire factory, NMOR at the 250 yg/m level (5, a leather tannery, NDMA at the 47 ]xg/wr level (jy, and a rocket fuel factory, NDMA at the 36 yg/m level (7). 

Leather Tanneries. N-nitrosodimethylamine has recently been shown (40) to be present as an air pollutant inside a leather tannery, at levels between 100 ng/m3 and 47,000 ng/m3. The average NDMA level in the 19 air samples where were collected was 17,000 ng/m3. This is the highest known human exposure to N-nitrosamines. 

Spiegelhalder B. 1984. Occupational exposure to N-nitrosamines. Air measurements and biological monitoring. lARC Sci Publ 57 937-942. 

Although food and tobacco products are important sources of external exposure to N-nitrosamines, exposure also occurs from nitrosamines produced internally in the digestive tract. About 5% of ingested nitrates are reduced to nitrites in sahva. These nitrites can subsequently react with secondary and tertiary amines, as well as N-substituted amides, carbamates and other related compounds, to form N-nitroso compounds within the gastrointestinal tract. This internal formation is a major source of human exposure to N-nitrosamines. 

During the last 4 years, a considerable discussion has been building up in biochemical and oncological circles on the possible carcinogenic risk presented by exposure to N-nitrosamines(49 ). The fact that carcinogenic N-nitrosamines are present in the diet may be regarded as established (SO) though the quantities may be less thw initially thou t. Since the question of a no-effect... 

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