EXPOSURE TO POLYCHLORINATED DIOXINS AND FURANS (PCDD/F) AND MORTALITY IN A COHORT OF WORKERS FROM A HERBICIDE-PRODUCING PLANT IN HAMBURG, FEDERAL-REPUBLIC-OF-GERMANY

The relation between mortality (all cause; cancer; cardiovascular diseases (Inrernational Classification of Diseases, Ninth Revision (ICD-9), codes 390-459); ischemic heart diseases (ICD-9 codes 410-414)) and exposure to polychlorinated dibenzo-p-dioxins and -furans (PCDD/F) was investigated in a retrospective cohort study. The cohort consisted of 1,189 male workers in a chemical plant in Hamburg, Federal Republic of Germany, who had produced phenoxy herbicides, chlorophenols, and other herbicides and insecticides known to be contaminated with 2,3,7,8-tetrachIorodibenzo-p-dioxin and other, higher chlorinated dioxins and furans. The authors reported previously on cancer mortality in this cohort for the follow-up period 1952-1989. The current study covers the years 1952-1992 and investigates the relation of PCDD/F exposure to mortality using a quantitative estimate of PCDD/F exposure for the whole cohort derived from blood and adipose tissue levels measured in a subgroup (n = 190). Quintiles and deciles of these estimates served as dose parameters in the estimation of relative risks (RRs), using year-of-birth stratified Cox regression. An unexposed cohort of gas workers served as an external reference group. The total mortality was elevated in all dose groups. The highest relative risk was observed for the highest 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) decile (RR = 2.43, 95% confidence interval (CI) 1.80 to 3.29). Cancer mortality and mortality due to ischemic heart diseases showed a dose-dependent relation with TCDD and all PCDD/F combined. The highest relative risks for cancer (RR = 3.30, 95% CI 2.05 to 5.31) and ischemic heart diseases (RR = 2.48, 95% CI 1.32 to 4.66) were observed in the highest PCDD/F exposure group. The pattern of effects and tests for trend were similar when the lowest exposure group within the chemical worker cohort served as the reference, but the relative risks were smaller and the confidence intervals were larger. Potential confounding exposures complicate the interpretation of the internal comparison. These findings indicate a strong dose-dependent relation between mortality due to cancer or ischemic heart diseases and exposure to polychlorinated dioxins and furans.