Estimation of the Cumulated Exposure to Polychlorinated Dibenzo-p-dioxins/furans and Standardized Mortality Ratio Analysis of Cancer Mortality by Dose in an Occupationally Exposed Cohort
You can manage bookmarks using lists, please log in to your user account for this.
Media type:
E-Article
Title:
Estimation of the Cumulated Exposure to Polychlorinated Dibenzo-p-dioxins/furans and Standardized Mortality Ratio Analysis of Cancer Mortality by Dose in an Occupationally Exposed Cohort
Description:
<p> For a cohort of 1189 male German former herbicide and insecticide workers with exposure to polychlorinated dibenzo-p-dioxins and -furans (PCDD/F), we report an extended standardized mortality ratio (SMR) analysis based on a new quantitative exposure index. This index characterizes the cumulative lifetime exposure by integrating the estimated concentration of PCDD/F at every point in time (area under the curve). Production department-specific dose rates were derived from blood levels and working histories of 275 workers by applying a first-order kinetic model. These dose rates were used to estimate exposure levels for all cohort members. Total mortality was elevated in the cohort; 413 deaths yielded an SMR of 1.15 (95% confidence interval [CI] 1.05, 1.27) compared to the mortality of the population of Germany. Overall cancer mortality (n = 124) was significantly increased (SMR = 1.41, 95% CI 1.17, 1.68). Various cancer sites showed significantly increased SMRs. The exposure index was used for an SMR analysis of total cancer mortality by dose. For 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) a significant trend (p=0.01) for the SMRs with increasing cumulative PCDD/F exposure was observed. The SMR in the first exposure quartile (0-125.2 ng/kg×years) was 1.24 (95% CI 0.82, 1.79), increasing to 1.73 (95% CI 1.21, 2.40) in the last quartile (≥2503.0 ng/kg×years). For all congeners combined as toxic equivalencies (TEQ) using international toxic equivalency factors, a significant increase in cancer mortality was observed in the second quartile (360.9-1614.4 ng/kg×years, SMR 1.64; 95% CI 1.13, 2.29) and the fourth quartile (≥ 5217.7 ng/kg×years TEQ, SMR 1.64, 95% CI 1.13, 2.29). The trend test was not significant. The results justify the use of this cohort for a quantitative risk assessment for TCDD and to a lesser extent for TEQ. </p>