Occurrence of volatile nitrosamines in food samples collected in three high-risk areas for nasopharyngeal carcinoma.

Fifty-four samples of foods consumed frequently in Tunisia, southern China and Greenland, all high-risk areas for nasopharyngeal carcinoma (NPC), were analysed for the presence of volatile nitrosamines by gas chromatography (GC) combined with a thermal energy analyser (TEA). Relatively high levels of N-nitrosodimethylamine (NDMA), N-nitrosopiperidine (NPIP) and N-nitrosopyrrolidine (NPYR) were found in Tunisian stewing base (touklia) and dried mutton preserved in olive oil (qaddid). In one Chinese salted and dried fish sample, a high level of NDMA (133 micrograms/kg) was detected, but for the 14 others the levels ranged from undetectable to 14 micrograms/kg, with a mean of 3 micrograms/kg. Similarly high levels of NDMA, were found in Eskimo dried, unsalted fish samples. NDMA, NPIP and NPYR at various levels were present in Chinese vegetables fermented in brine. The possible role of nitrosamines in the etiology of NPC is discussed.