Role of Polychlorinated Dibenzofuran in Yusho (PCB Poisoning)

Abstract

In the blood of 15 patients with yusho or "polychlorinated biphenyl poisoning" that occurred in 1979 in Taiwan, was found polychlorinated dibenzofurans (14 of 15) and polychlorinated quaterphenyls (15 of 15), as well as polychlorinated biphenyls (15 of 15). The mean concentration ratio of these substances was approximately 1 : 160 : 500. Based on the following evidence, we propose that polychlorinated quaterphenyls were major pathogenic substances in the development of yusho: (1) Clinical manifestations and course of yusho patients are disproportionately severe and persistent for the observed blood levels of polychlorinated biphenyls, while patients who were occupationally exposed to pure polychlorinated biphenyls take characteristically mild and benign clinical course despite polychlorinated biphenyl levels often much higher than those noted in yusho patients; (2) Polychlorinated debenzofurans show a marked tendency to accumulate in the liver, which might explain frequent presence of jaundice and other abdominal symptoms in yusho, which are, again, not observed in those with occupational polychlorinated biphenyl poisoning; (3) Toxicity of polychlorinated dibenzofurans is a hundred to ten thousand times greater than that of polychlorinated biphenyls and polychlorinated quaterphenyls in animal experiments.

Placental markers of human exposure to polychlorinated biphenyls and polychlorinated dibenzofurans.

“…The EGF receptor autophosphorylation effect correlated well with the decrease in birth weight observed in offspring of exposed women, suggesting that this biochemical event might provide a good marker of effect for the toxic halogenated aromatics. Two PCDF congeners (2,3,4,7,2,3,4,7, were detected in Yu-Cheng placentae but not controls. Several PCBs were also detected (including the 2,2',4,4',5,5'-hexa-CB and 2,3,3',4,4',5-hexaCB) in much higher concentrations in Yu-Cheng placentae.…”

Surveys of Workers Occupationally Exposed to PCBs and of Yusho Patients

“…PCDFs were detected in tissues of Japanese Yusho patients (17), and Kashimoto et al (18) detected them in the blood of "fresh" Taiwanese patients though they could not be detected in "old" Japanese Yusho patients. From the results of animal experiments, Hori et al (19,20) concluded that PCDFs had played an important role in the manifestation of Yusho findings.…”

“…Testing for PCQs in the blood is an important means of determining whether a subject has been exposed to Yusho-type chlorinated hydrocarbons (i.e., PCBs, PCQs and PCDFs) or only to PCBs, though the toxicity of PCQs themselves is almost equal to that of PCBs (18). In view of these reports, groups A and C can be judged to have been exposed only to PCBs, because PCQ levels were lower than the detection limit of 0.02 ppb in the two groups.…”

Chlorinated and brominated dioxins and dibenzofurans in human tissue following exposure.

“…Figure 17 (47) illustrates dioxin and dibenzofuran congener levels from a well-known rice oil poisoning, the Yusho incident of 1968 in Fukuoka, Japan (48,49 (50,5). The Binghamton incident, as noted previously, showed elevation ofsome ofthese congeners in some exposed workers.…”