Mortality after exposure to polychlorinated biphenyls and dibenzofurans: 30 years after the "Yucheng accident".

In 1979, approximately 2,000 people in central Taiwan were accidentally exposed to polychlorinated biphenyls and dibenzofurans due to ingestion of contaminated cooking oil. This event was called Yucheng, "oil-syndrome" in Chinese. We followed the exposed persons and compared their cause-specific mortality with that of neighborhood referents 30 years after the accident. We obtained age- and gender-matched referents from the 1979 neighborhoods of the exposed people. Cause-specific mortality was compared between exposed subjects (N=1803) and their neighborhood referents (N=5170) using standardized mortality ratios (SMR). Total person-years for the Yucheng subjects and neighborhood referents were 48,751 and 141,774, respectively. The SMR for all causes (SMR=1.2, 95% CI: 1.1-1.3), diseases of the circulatory system (SMR=1.3, 95% CI: 1.0-1.6), and diseases of the musculoskeletal system and connective tissue (SMR=6.4, 95% CI: 2.8-12.7) were elevated in Yucheng subjects. Among Yucheng males, the SMRs for diseases of the digestive system (SMR=1.9, 95% CI: 1.2-2.8), malignant neoplasm of stomach (SMR=3.5, 95% CI: 1.5-7.0), and malignant neoplasm of lymphatic and hematopoietic tissue (SMR=3.0, 95% CI: 1.1-6.6) were increased. The SMR for total neoplasms was increased (SMR=1.3, 95% CI: 0.9-1.7). We conclude that exposure to PCBs/PCDFs at levels that produced symptoms in many affects mortality patterns 3 decades after exposure.