Levels of polychlorinated dibenzo-p-dioxins and dibenzofurans in workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin.
Nineteen subjects exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (1746016) (2,3,7,8-TCDD), and who were previously found to have widely disparate levels of 2,3,7,8-TCDD in adipose tissue, were investigated to determine the cause of this phenomenon. The participants in the present study had previously demonstrated 2,3,7,8-TCDD levels ranging from 3.5 to 750 parts per trillion (ppt). Adipose tissue and serum samples were reanalyzed for 2,3,7,8- TCDD, and individual job history data was extracted from the original questionnaires. Employment records of the 19 participants were analyzed to evaluate exposure. Sixteen of the participants had worked at the same chemical factory; process records of the factory were analyzed to determine areas and periods of high exposure risk. Nine of the participants had worked in an area where 2,4,5- trichlorophenol (95954), hexachlorophene (70304), or 2,4,5- trichlorophenoxacetic-acid (93765) was produced. Three were truckers who had worked near 2,3,7,8-TCDD contaminated waste oils. Adipose tissue levels of 2,3,7,8-TCDD in the nine factory employees with exposure ranged from 41.9 to 750ppt, while those in the seven others ranged from 3.5 to 25.8ppt, a statistically significant difference. Levels in the three truckers ranged from 7.8 to 24.7ppt. Lipid adjusted serum levels demonstrated similar results. The authors conclude that stratification by exposure level explains the wide ranging levels of 2,3,7,8-TCDD in persons reporting occupational exposure to this compound.