ISSN:0030-2414    

DOI:10.1159/000225433

出版商:S. Karger AG    

年代:1980

数据来源: Karger

ISSN:0030-2414    

DOI:10.1159/000225434

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

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 μg/kg with N-nitrosodimethylamine (NDMA) present in all samples up to 5 μg/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/μg/kg of NDMA in these samples with the exception of beer where NDMA levels of up to 12 μg/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 N

ISSN:0030-2414    

DOI:10.1159/000225435

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

The largest human exposure to N-nitrosamines is in the industrial section. Leather tanners are exposed to N-nitrosodimethylamine at levels up to 47 μg/m3, corresponding to 440 μg/person/day. Workers in the curing area of tire factories are exposed to N-nitrosomorpholine at levels up to 27 μg/m3, corresponding to a intake of 250 μg/person/day. These industrial exposures are considerably greater than exposure via foodstuffs, beer, cosmetics, cutting fluids and herbici

ISSN:0030-2414    

DOI:10.1159/000225436

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

In total, 201 duplicates of all foods and drinks sampled by adult volunteers during a 24-hour sampling period have been analyzed for nitrate, nitrite and volatile N-nitrosamines. For nitrate the mean daily intake was equivalent to 179 mg of potassium nitrate per 24 h, for nitrite this intake was equivalent to 4.2 mg of sodium nitrite per 24 h. The best estimate for the total daily fraction of salivary nitrite originating from dietary nitrate has been calculated as 6.3 mol%/24 h. For N-nitrosodimethylamine the mean daily intake was 0.38 μg/24 h. The most important source of this nitrosamine contributing to the daily dietary intake was shown to be beer, which contributes 71% of the intake of an average consumer. Finally, attention has been drawn to the identification of N-nitroso-5-methyl-l,3-oxazolidine as an environmental nitrosamine present as an impurity in cutting fluids

ISSN:0030-2414    

DOI:10.1159/000225437

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

The results of the systematic survey of food from the German market in regard to the occurrence of volatile nitrosamines are presented. The average daily intake for male persons amount to 1.1 μg for N-nitroso-dimethylamine (NDMA) and 0.1-0.15 μg for N-nitroso-pyrrolidine (NPYR). About 64% of this total daily intake for NDMA is found in beer, 10% result from cured meat products. The surprising contamination of beer is formed during the drying (kilning) of malt and can be eliminate

ISSN:0030-2414    

DOI:10.1159/000225438

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

Volatile N-nitrosamines were quantitatively determined in mainstream and sidestream smoke of commercial cigarettes using gas chromatography-thermal energy analysis (GLC-TEA). The smoke was trapped in ascorbic acid solution buffered at pH 4.5 and then extracted with dichloromethane; the organic phase was chromatographed on basic alumina and analyzed by GLC-TEA. The mainstream smoke of 22 different commercial cigarettes from Germany and Switzerland contained between 0.1 and 27 ng dimethylnitrosamine (DMN), 1.5 and 29 ng nitrosopyrrolidine (NPY) and traces of methylethylnitrosamine (MEN). The side-stream smoke of these cigarettes contained between 143 and 415 ng DMN, 3.1 and 27 ng MEN and 28 and 150 ng NPY. In a final experiment we measured the DMN concentration in a sealed experimental chamber as a function of the number of cigarettes smoked and recovered 68-87% of the DMN values found when using the sidestream collection device applied in the other experiments.

ISSN:0030-2414    

DOI:10.1159/000225439

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

Formation of N-nitroso compounds from amines and nitrite has been demonstrated in chemical systems and in the stomach of animals in vivo. The amines differ in the extent to which they give rise to N-nitroso compounds. Many amines are common in the environment. Other amines are ingested as drugs, food additives or as trace contaminants of food with agricultural chemicals. At least 20 such amines have been given chronically to rats together with sodium nitrite and the incidence of tumors compared with that in rats given the amine or nitrite alone. Until now 13 of these amines have given rise to a significant incidence of tumors under these conditions, indicating that ingestion of these amines when nitrite is present could provide a source of carcinogenic nitrosamines for man. Some of the amines were more effective in this respect than others. These were amino-pyrine, morpholine, disulfiram, methylbenzylamine and heptamethyleneimine.

ISSN:0030-2414    

DOI:10.1159/000225440

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

A survey is given on the occurrence of nitrate and nitrite in human saliva and the influence of the dietary nitrate intake. Nitrate, after its absorption in the upper gastrointestinal tract, reaches the salivary glands via the blood circulation where it is secreted into the oral cavity and partially reduced to nitrite by the oral microflora. There is a linear relationship between the amounts of nitrate ingested and amounts of nitrate and nitrite found in saliva. The ability of the oral microflora to reduce nitrate to nitrite depends on the individual ages. Mean salivary nitrite was found to increase from well below 1 ppm in infants of up to 6 months to about 7 ppm in adults. A remarkably different situation has been found in areas of high esophageal cancer incidence in Iran: although dietary intake of nitrate and nitrite is very low, nitrite levels in saliva, especially in children of this area tend to be much higher than those in children of western European countries.

ISSN:0030-2414    

DOI:10.1159/000225441

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

A simple mathematical model is formulated to estimate the order of magnitude of the flux of N-nitrosodimethylamine, based upon blood concentrations and the assumption of a quasi steady state between formation and metabolism. The model predicts a total daily exposure which corresponds to an extrapolated risk well within the observed risk for liver cancer in the USA. The ramifications of this model are significant for cancer prevention and for the development of techniques of risk extrapolation.

ISSN:0030-2414    

DOI:10.1159/000225442

出版商:S. Karger AG    

年代:1980

数据来源: Karger