A retrospective job exposure matrix for estimating exposure to 2,3,7,8-tetrachloredibenzo-p-dioxin

Background A job exposure matrix was developed to estimate the 2,3,7,8-tetr achlorodibenzo-p-dioxin exposure of 3,538 workers who produced 2,4,5-trichl orophenol and its derivatives. Methods Daily TCDD exposure scores that were plant, process, and period spe cific were estimated for each job title as the product of 1) the concentrat ion of TCDD (mu g/g); 2) a qualitative factor to account for the extent of worker contact and 3) time exposed to TCDD contamination. Daily scores were summed to compute individual cumulative TCDD exposure scores. Results Daily TCDD exposure scores ranged from 0.001 to 1,250. Cumulative T CDD scores ranged from 0.002 to 1,559,430. The 393 workers with records of chloracne in the TCDD exposure cohort (11%) had markedly higher cumulative scores than those with no record of chloracne (a median score of 11,546 vs. 77). Conclusion The cumulative TCDD exposure scores incorporate both duration an d level of exposure, and permit the relative ranking of worker exposures fo r the evaluation of exposure-response relationships between TCDD exposure a nd mortality in an updated cohort study analysis. Am. J. Ind. Med. 38:28-39 , 2000. Published 2000 Wiley-Liss, Inc.(dagger)