This report consists of an updated analysis of a cohort examined in two previous studies (De Carli ed al, Brit.J.Cancer 1985,51:707-712 and Piolatto et al, Brit.J.Cancer 1991,63:457-459) on bladder cancer mortality of workers exposed in a dyestuff factory in a district of Turin (Northern Italy), where exposure to carcinogenic aromatic amines occurred up to 1972. This study comprised 664 exposed subjects followed-up in the period 1946-2003, for a total of 16,544 man-years at risk. Regional death rates were used to calculate SMRs as an estimate of relative risks for specific death causes. Overall, there were 58 bladder cancer deaths vs. 2.8 expected, corresponding to a SMR of 20.7. As reported in the above studies, the SMR was much higher (62.0) for workers engaged in Benzidine and 2-Naphtylamine manufacture and somewhat higher (26.6) for those who worked in Fuchsine manufacture and were exposed to o-toluidine. The effect of various temporal factors on relative risk was evaluated by including in the analysis age at first exposure, duration and time since the last exposure. No clear trend was found for exposure duration, whereas for age at first exposure and time since cessation, the risk associated with both variable levels decreased with increasing age and time. However, the excess risk (number of cases) persisted up to 30 years since last exposure and declined thereafter. Our findings suggest, under the multistage theory, that it is likely that the aromatic amines act on more the one stage of the process, by involving both initiation and promotion. These results are of interest because of their implications on a theoretic (carcinogenesis) and practical (public health) level, especially as far as the need of stopping both occupational exposure and voluntary habits (smoking) is concerned.
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