Serum concentrations of chlorinated dibenzo-p-dioxins and dibenzofurans among former Michigan trichlorophenol and pentachlorophenol workers

This study examines serum levels of 2,3,7,8-substituted chlorinated dioxins and furans, and PCBs for 375 Michigan workers with potential chlorophenol exposure, 37 Worker Referents, and 71 Community Referents. The chlorophenol workers were last exposed to trichlorophenol and/or pentachlorophenol 26-62 years ago. Employees working only in the trichlorophenol units had mean lipid-adjusted 2378-tetrachlorodibenzo-p-dioxin (TCDD) levels of 15.9 ppt compared with 6.5 ppt in the Worker Referents. Employees working only in the pentachlorophenol units had mean lipid-adjusted levels for 123478-H6CDD of 16.1 ppt, 123678-H6CDD of 150.6 ppt, 123789-H6CDD of 20.2 ppt, 1234678-H7CDD of 192.6 ppt, and OCDD of 2,594.0 ppt compared with the Worker Referent levels for the same congeners of 7.5, 74.7, 8.6, 68.7, and 509.1 ppt, respectively. All furan and PCB levels among workers in the trichlorophenol and/or pentachlorophenol departments were similar to the Worker Referents. The Tradesmen who worked throughout the plant had dioxin congener profiles consistent with both trichlorophenol and pentachlorophenol exposures. PCB levels and levels of 23478-P5CDF, 123478-H6CDF, and 123678-H6CDF were also greater in these Tradesmen than in the Worker Referents. The Worker Referent group had higher levels of dioxins and furans than the Community Referents indicating the potential for exposure outside the chlorophenol departments at the site. Distinct patterns of dioxin congeners were found many years after exposure among workers with different chlorophenol exposures. Furthermore, past trichlorophenol exposures were readily distinguishable from past pentachlorophenol exposures based on serum dioxin evaluations among workers. These data can be used to better assess dioxin exposures in future health studies.