[Reanalysis of mortality in a petrochemical plant producing vinyl chloride and XXXX ].

@entity1 @entity706 @entity96 @entity5 @entity2634 @entity1313 @entity2 @entity1778 @entity1575 @entity204 @entity65
OBJECTIVE: To study @entity5 mortality among main subgroups of workers employed in VC/ @entity2634 production potentially exposed to toxics and carcinogens. MATERIALS AND METHODS: We reanalyzed the mortality of 1,658 males (follow up 1972-1995; 35,626 @entity1 years; 170 @entity204 ) by Poisson regression, adjusting for age, age at hiring, calendar period, length of exposure and latency. We calculated the relative risks (RR) and the 95% confidence intervals (CI) for @entity2634 baggers (n. = 197), @entity2634 compound (n. = 403) and autoclave (n. = 209) workers. As an internal reference we used two groups of workers: technicians and employees (main reference: n. = 202 subjects), with the group of other blue collar workers (n. = 639) added for statistical purposes only (minor reference: n. = 841 subjects). RESULTS: Pooling the four subgroups of exposed workers, the comparison with the main reference group allowed us to detect increased mortality from all causes of @entity204 (RR = 2.09; CI = 1.09-4.00; 160 @entity204 ), all @entity5 (RR = 1.53; ns; 81 @entity204 ), @entity2 (RR = 2.05; ns; 29 @entity204 ) and @entity65 (RR = 3.57; ns; 29 @entity204 ). The analysis for each specific subgroup revealed increased mortality from all causes of @entity204 among both @entity2634 baggers (RR = 2.66; CI = 1.27-5.59) and @entity2634 compound workers (RR = 2.68; CI = 1.36-5.27). Comparison of the minor reference group with the overall population of exposed workers showed increased RRs for other diseases, namely, @entity96 (RR = 4.08; ns; 9 @entity204 ), @entity706 and @entity1778 (RR = 2.97; ns; 7 @entity204 ) and @entity1575 (RR = 3.30; ns; 11 @entity204 ). The analysis for each specific subgroup revealed significantly increased RR for all @entity5 among @entity2634 compound workers (RR = 1.74; CI = 1.06-2.85), for @entity2 among @entity2634 baggers workers (RR = 3.04; CI = 1.15-7.99) and for @entity96 (RR = 9.57; CI = 1.69-54.1) and @entity1575 (RR = 6.32; CI = 1.37-29.07) among autoclave workers. In addition, the two @entity204 from @entity1313 were observed among @entity2634 compound workers. CONCLUSIONS: To highlight the risk previously reported in the literature and to reduce the possible dilution effect (due to comparison bias, healthy worker effect), it proved methodologically pivotal to separate exposed and probably unexposed workers (considered as an internal reference group).
