Occupational and nonoccupational risk factors for bladder cancer were analyzed in a cohort of 1385 workers with known exposure to a potent bladder carcinogen, beta-naphthylamine. Bladder cancer was approximately seven times (95% confidence interval [CI] = 3.9, 12.4) more likely in exposed rather than nonexposed individuals, yet, otherwise, the groups were generally similar in other exogenous or hereditary risk factors. A total of 13 cases of bladder cancer were identified. After the first year of a screening program involving 380 members of the cohort, 9 of the 13 cases of bladder cancer and 36 persons with atypical bladder cytology, histology, or pathology were compared with 335 noncases for distributions of different variables. Occupational variables were significant in a multivariate model that controlled for age, cigarette smoking history, and source of drinking water. The estimated odds ratio for the association for bladder cancer and the duration of employment, when controlling of these other variables, is 4.3 (95% CI = 1.8, 10.3). In addition to the occupational factors, age was significant in the multivariate analysis. Other potential risk factors, such as consumption of coffee or artificial sweeteners, use of phenacetin, or decreased use of vitamin A were not found to be significantly different in cases and noncases.

Kaolin is removed from underground seams in the mining area to a processing area, where it is sliced, dried, and pulverised to make the finished product. A study was undertaken to determine the dust concentrations in various work areas and to assess the prevalence of radiographic and pulmonary function abnormalities in 65 workers at a Georgia kaolin mine. Respir

A marker for biological response to bladder carcinogen exposure was evaluated in a cross-sectional study of 504 workers at high risk due to a range of exposures to various carcinogenic aromatic amines, primarily 2-naphthylamine. A quantitative fluorescence cytology method using the DNA-binding dye, acridine orange, was employed to measure DNA in exfoliated urothelial cells. DNA hyperploidy (greater than 5 C) was observed in 16 (21.6%) of 74 workers who had been exposed compared with 15 (3.5%) of 430 workers who had not (p less than 0.001). The prevalence of DNA hyperploidy increased in a dose-response manner from 3.5% to 60% with increasing duration of exposure. The association between DNA hyperploidy and exposure persisted when adjustment was made for age and cigarette smoking (p = 0.0001). The prevalence of the marker was greatest for exposed workers who smoked (23%), and lowest for those who had no exposure and who had not smoked (2%). This study indicates that DNA hyperploidy can serve as a marker for identifying workers who are at increased risk in occupational groups exposed to bladder carcinogens.

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