American Journal of Epidemiology Advance Access first published online on October 30, 2008
This version published online on November 10, 2008
American Journal of Epidemiology, doi:10.1093/aje/kwn295
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Original Contribution |
Mortality After Exposure to Polychlorinated Biphenyls and Polychlorinated Dibenzofurans: A 40-Year Follow-up Study of Yusho Patients
Correspondence to Dr. Daisuke Onozuka, Department of Information Science, Fukuoka Institute of Health and Environmental Sciences, 39 Mukaizano, Dazaifu-shi, Fukuoka 818-0135, Japan (e-mail: onozuka{at}fihes.pref.fukuoka.jp).
Received for publication July 1, 2008. Accepted for publication August 14, 2008.
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.
cohort studies; food contamination; mortality; neoplasms; polychlorinated biphenyls
Abbreviations: CDF, chlorinated dibenzofuran; CI, confidence interval; ICD, International Classification of Diseases; PCB, polychlorinated biphenyl; PCDF, polychlorinated dibenzofuran; SMR, standardized mortality ratio