Polychlorinated biphenyls (PCB), thyroid hormones and cytokines in construction workers removing old elastic sealants

OBJECTIVES To estimate the internal PCB level in Swedish workers specialised in PCB abatement in buildings and to measure possible effects of PCB on thyroid function and aspects of the immune system. METHODS Thirty six of 40 eligible workers (90%) removing old elastic sealants containing PCB and 33 control construction workers provided blood samples for determination of 19 PCB congeners and some other organochlorine compounds (hexachlorobenzene and p,p'-DDE), thyroid function hormones and a set of cytokines. The PCB exposed group was reinvestigated after 10 months for a trend assessment. RESULTS The sum of 19 PCB congeners in blood plasma from the occupationally PCB-exposed group was twice the level in the controls (geometric mean 580 vs. 260 ng/g lipid; P < 0.001), and there was also some difference in p,p'-DDE between the groups while the lipid-adjusted hexachlorobenzene levels were of the same magnitude. No statistically significant increase in overall PCB levels was observed in the abatement workers at follow-up and some congeners even declined. Thyroid function was not associated with PCB exposure at the current levels and this applied also to the cytokines investigated. CONCLUSIONS Swedish workers removing old elastic sealants with PCB have a higher internal PCB load than unexposed colleague construction workers, tentatively secondary to historical exposure. A system of protective measures seemed to be efficient since no further increase was noted after a longish period of additional exposure. There was no evidence of thyroid function or immune system involvement, as expressed by a set of cytokines, at the low PCB levels recorded.