Oculodermatological findings in workers with occupational exposure to polychlorinated biphenyls (PCBs)

Oculodermatological findings, such as hypersecretion of the Meibomian glands, swelling of the upper eyelids and hyperpigmentation of the conjunctivae are considered typical of "PCB poisoning." They were common clinical manifestations of yusho and yu-cheng, two epidemics in Japan and Taiwan caused by the ingestion of rice cooking oil contaminated with polychlorinated biphenyls (PCBs) and polychlorinated dibenzofurans. To investigate the prevalence of such abnormalities in a population with long term occupational exposure to PCBs, a group of 326 workers employed in two capacitor manufacturing facilities were investigated in 1976, and 195 of these again in 1979. The median blood values of lower homologues of PCBs were 63 ppb (in plasma) in 1976 and 49 ppb (in serum) in 1979, and of the higher homologues 18 ppb and 17 X 5 ppb respectively. The prevalence of oculodermatological findings potentially related to the effects of PCBs were 9 X 4% and 13 X 3% at the two examinations. There was no significant association between such abnormalities and blood plasma/serum concentrations of PCBs. The observations in this work population exposed to PCBs differ from the yusho and yu-cheng experiences in that fewer clinical abnormalities were found. Suggestions are made that it may be inappropriate to extrapolate findings from the well known PCB poisoning episodes to exposures in occupational settings and that attention should be paid to the importance of polychlorinated dibenzofurans as an aetiological factor in human PCB poisoning.