Gliomas and meningiomas in men in Los Angeles County: investigation of exposures to N-nitroso compounds.

We conducted a case-control study of primary tumours of the brain and cranial meninges in Los Angeles County to investigate the hypothesis that these tumours are related to occupational exposures. We also collected limited data on diet and personal habits that are likely to involve exposure to N-nitroso compounds (NOC), NOC precursors and modulators of NOC metabolism. Interviews were conducted with 272 men with a brain tumour diagnosed in 1980-84 and with 272 individually matched neighbourhood controls. The study was of sufficient size to allow for separate analyses of the 202 pairs of glioma patients and of the 70 patients of meningioma. Six glioma cases and one control had worked in the rubber industry, in which excesses of brain tumour have been shown in previous studies and where there are high levels of volatile NOC at various work sites. Ten meningioma patients and five controls had used cooling, cutting or lubricating oils, and most had used these daily (eight cases; four controls). Cases and controls were not different, however, with respect to other occupations known to involve exposures to NOC. Cases and controls also did not differ in their consumption of alcoholic beverages or cigarettes or in their passive exposure to cigarette smoke. The most striking dietary finding was a significant protective effect among glioma pairs of use of vitamin supplements, which increased with increasing frequency of use (p for trend = 0.04; odds ratio for use at least twice a day = 0.4 (95% confidence interval = 0.24-0.77)).(ABSTRACT TRUNCATED AT 250 WORDS)