Human exposure to preformed environmental N-nitroso compounds in the UK

The Laboratory of the Government Chemist has been investigating the presence of N-nitrosamines in various foodstuffs for the last 12 years; work concentrating on those foods in which nitrosamines are thought to be formed. The studies showed that fried bacon contained N-nitrosopyrrolidine (NPYR) in the range of 1--10 microgram/kg with N-nitrosodimethylamine (NDMA) present in all samples up to 5 microgram/kg. Fish and cheese were examined and some samples were found to contain low levels of NDMA. A wide variety of other food samples were examined, the levels, however, did not exceed 0.5 microgram/kg of NDMA in these samples with the exception of beer where NDMA levels of up to 12 microgram/kg were found. Air sampling was undertaken at various sites in the UK, however, no positive evidence was found for the presence of N-nitrosamines in normal air in the UK. Mainstream tobacco smoke was also examined, values of up to 10 ng of NDMA per cigarette were obtained. Samples of rain and river water were analysed, traces of NDMA and N-nitrosomorpholine occasionally being found; however, nitrosamines were not found in any of the samples of drinking water examined. An assessment was made of the average intake of N-nitrosamines from food, beer and cigarettes and the human exposure from these sources is somewhat less than in other European countries. some occupational sources of exposure to N-nitrosamines were also considered; cutting fluids were examined for the presence of N-nitrosodiethanolamine and certain herbicides were examined for NDMA.