Mortality After Exposure to Polychlorinated Biphenyls and Polychlorinated Dibenzofurans: A 40-Year Follow-up Study of Yusho Patients

Abstract

A 40-year follow-up study was conducted to examine mortality among 1,664 patients in Japan suffering from "Yusho," a disease caused by ingestion of rice oil contaminated with polychlorinated biphenyls and polychlorinated dibenzofurans. To evaluate the effects of exposure on mortality, the authors calculated standardized mortality ratios. National mortality rates for major causes of death were used as reference points. A total of 1,596 Yusho patients (95.9%) were followed until death or the end of the study (December 31, 2007). The standardized mortality ratios for most major causes of death were not significantly elevated, with the exceptions of all types of cancer (standardized mortality ratio (SMR) = 1.37, 95% confidence interval (CI): 1.11, 1.66), liver cancer (SMR = 1.82, 95% CI: 1.06, 2.91), and lung cancer (SMR = 1.75, 95% CI: 1.14, 2.57) in males. In addition, the standardized mortality ratios for all cancers, liver cancer, and lung cancer among males tended to decrease over time. Results from this study suggest that the carcinogenicity of polychlorinated biphenyls and polychlorinated dibenzofurans must be taken into account when evaluating mortality risk.

Mortality after exposure to polychlorinated biphenyls and dibenzofurans: 30 years after the “Yucheng Accident”

“…They occur mostly in males, which is also true in the 40 year follow-up from Yusho in Japan(Onozuka et al, 2009). The predominant excesses in Japan are in liver and lung cancer, with a small increase in stomach cancer, whereas we see excesses in stomach and haematopoietic malignancies, and no liver cancer excess.…”

Metabolism and metabolites of polychlorinated biphenyls

“…While this classification was based on positive correlation between PCB exposure and incidences of melanoma and limited evidence of an involvement in the development of breast cancer and non-Hodgkin lymphoma, exposure to PCBs has also been correlated with an increased incidence of other malignancies including hepatocellular carcinoma and lung cancer (Onozuka et al, 2009, Todaka et al, 2009). In addition, exposure to several Aroclor PCB mixtures resulted in the formation of thyroid neoplasms in male Sprague-Dawley rats, a finding that is in agreement with similar in vivo studies (Mayes et al, 1998, Vansell et al, 2004).…”

Oxidative DNA adducts after Cu2+-mediated activation of dihydroxy PCBs: Role of reactive oxygen species

“…Similar effects of PCB toxicity were observed in the more than 2000 people affected by this latter incident. In a 40 year follow-up study of the Yusho accident examining the mortality of 1,664 patients, men showed an elevated mortality, compared to the general population, from all types of cancer, particularly lung and liver, while in women the mortality ratio was only increased for liver cancer (6). A similar follow-up study of the Yucheng accident did not find any increase in cancer mortality in either sex, as compared to the general Taiwanese population, but did find an early increase in liver mortality in men and a delayed increase in systemic lupus erythematosus mortality was found in women (7).…”