Chlorinated dibenzo-p-dioxins, dibenzofurans, and biphenyl profiles of workers with trichlorophenol and pentachlorophenol exposures

Abstract

We examined the serum lipid adjusted levels of 2,3,7,8-substituted chlorinated dioxins and furans, and four coplanar PCBs for 98 workers. We found workers who worked only in the trichlorophenol units had mean lipid adjusted 2,3,7,8-TCDD levels of 36.8 ppt significantly higher (p < 0.05) than 6.0 ppt in the reference group. Workers who worked only in the pentachlorophenol units had mean lipid adjusted levels for 123478-HxCDD of 14.8 ppt, 123678-HxCDD of 156.4 ppt,123789-HxCDD of 23.7 ppt, 1234678-HpCDD of 234.6 ppt, and OCDD of 2,778.2 ppt significantly higher (p < 0.05) than the reference group levels for the same congeners of 7.5, 71.8, 8.0, 67.5, and 483.2 ppt, respectively. While we did find 12378-PeCDD levels higher than the reference group in trichlorophenol and pentachlorophenol workers, the differences are small, and could be attributed to normal variation. All furan levels among the trichlorophenol or pentachlorophenol only workers were not significantly different than the reference group. Workers with both trichlorophenol and pentachlorophenol exposures had mean dioxin levels consistent with complex chlorophenol exposures. Tradesmen who worked throughout the plant had congener profiles consistent with both trichlorophenol and pentachlorophenol exposures. PCB 169, 23478-PeCDF, 123478-HxCDF, and 123678-HxCDF levels were also significantly greater (p < 0.05) in these tradesmen than in the reference group. We found distinct patterns of dioxin congeners many years after exposure among workers with different chlorophenol exposures. We were effectively able to distinguish past trichlorophenol exposures from pentachlorophenol exposures based on differing serum dioxin profiles among workers.

Introduction

Polychlorodibenzo-p-dioxins and polychlorodibenzofurans may be formed as unintended by-products in the production of 2,4,5-trichlorophenol (TCP) and pentachlorophenol (PCP). Studies of persons with significant TCP exposures find 2,3,7,8 tetrachlorodibenzo-p-dioxin (2378-TCDD) levels above background with some of these studies also reporting elevated 12378-PeCDD levels (Nygren et al., 1988, Beck et al., 1989, Papke et al., 1992, Piacitelli et al., 1992, Smith et al., 1992, Ott et al., 1993, Littorin et al., 1994, Flesch-Janys et al., 1996, Heederik et al., 1998, Ryan and Schecter, 2000). Persons exposed to PCP often have 123478-HxCDD, 123678-HxCDD, 123789-HxCDD, 1234678-HpCDD, and OCDD levels above background. Some studies also report higher 12378-PeCDD, 123478-HxCDF, and 1234678-HpCDF levels (Ryan et al., 1987, Papke et al., 1992, Littorin et al., 1994, Schecter et al., 1994, Flesch-Janys et al., 1996, Schecter et al., 1996, Coenraads et al., 1999).

We examined serum dioxin, furan, and PCB levels among former workers in production of TCP and PCP, and compared these levels with workers at the same plant without potential for workplace exposures. These chlorophenol workers have been studied previously in several epidemiology studies (Townsend et al., 1982, Bond et al., 1983, Bond et al., 1989, Bodner et al., 2003). The current study is unusual because workers may have been exposed to either or both TCP and PCP. Thus this study provides a rare opportunity to compare 2,3,7,8-substituted chlorinated dioxins and furans profiles among two types of chlorophenol workers. We will determine if the dioxin and furan profiles for our workers differ from previous studies of TCP and PCP workers, and how distinct the dioxin “fingerprints” are for these chlorophenols many years after workplace exposures have ceased.