Nitrate exposure and the carcinogenic process.
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Animals↗
Biomedical subjects
S Al-Dabbagh
Publications and source records attributed to S Al-Dabbagh.
Mortality of nitrate fertiliser workers.
An epidemiological cohort study was conducted to investigate the mortality patterns among a group of workers engaged in the production of nitrate based fertilisers. This study was designed to test the hypothesis that individuals exposed to high concentrations of nitrates might be at increased risk of developing cancers, particularly gastric cancer. A total of 1327 male workers who had been employed in the production of fertilisers between 1946 and 1981 and who had been occupationally exposed to nitrates for at least one year were followed up until 1 March 1981. In total, 304 deaths were observed in this group and these were compared with expected numbers calculated from mortality rates in the northern region of England, where the factory was located. Analysis was also carried out separately for a subgroup of the cohort who had been heavily exposed to nitrates--that is, working in an environment likely to contain more than 10 mg nitrate/m3 for a year or longer. In neither the entire cohort nor the subgroup was any significant excess observed for all causes of mortality or for mortality from any of five broad categories of cause or from four specific types of cancer. A small excess of lung cancer was noted more than 20 years after first exposure in men heavily exposed for more than 10 years. That men were exposed to high concentrations of nitrate was confirmed by comparing concentrations of nitrates in the saliva of a sample of currently employed men with control men, employed at the same factory but not in fertiliser production. The men exposed to nitrate had substantially raised concentrations of nitrate in their saliva compared with both controls within the industry and with men in the general population and resident nearby. The results of this study therefore weight against the idea that exposure to nitrates in the environment leads to the formation in vivo of material amounts of carcinogens.
Aged↗
Geographic and social class variation within the UK in levels of salivary nitrates and nitrites. A preliminary report.
In the study, the first results of which are reported here, salivary nitrate and nitrite levels were examined in populations drawn from regions of the UK which differ in mortality rates for gastric cancer. The aims were to see, firstly, whether there was an equivalent geographic variation for nitrate and nitrite levels and, secondly, whether within each region any socio-economic or dietary characteristics correlated with the salivary levels. The results show that the nitrate and nitrite levels are significantly higher in residents from the Oxford region (low gastric cancer incidence area) than in residents from the north-east of England and north Wales (high-incidence areas). Further, within each area there is a noticeable relationship between nitrate and nitrite levels and age and social class. The social class trend is, as with the geographic trend, the inverse of that for stomach cancer risk. It is felt that the explanation of these results is probably a greater consumption of fresh, nitrate-containing vegetables by people in the Oxford region and by those in higher socio-economic groups. The implications that these results have for the nitrate hypothesis in relation to gastric cancer is discussed.
Adolescent↗
Nitrates, nitrites and gastric cancer in Great Britain.
Nitrate and nitrite were measured in the saliva of two populations who differed in their risk of developing gastric cancer. Surprisingly, the levels of both ions were significantly higher in the low-risk group.
Adolescent↗