In 1979, a mass poisoning occurred in central Taiwan from cooking oil contaminated by dioxin-like chemicals polychlorinated biphenyls (PCBs) and dibenzofurans (PCDFs). Symptoms included chloracne, hyperpigmentation, and peripheral neuropathy, and the illness was referred to as "Yucheng" (oil disease). We have regularly followed the victims of this event, and studied health outcomes.
　　 A mortality follow-up 30 years after the event found the Yucheng people had increased overall mortality, malignant neoplasm of stomach, and malignant neoplasm of lymphatic and hematopoietic tissue, myocardial infarction, and chronic liver diseases and cirrhosis among males, and increased diseases of the circulatory system, and systemic lupus erythematous in females. Morbidity studies found that Yucheng victims had more chloracne, hyperkeratosis, abnormal nails, skin allergy, and goiter than the background exposure groups. Yucheng women had higher rates of contracting diabetes, and had more memory problems when aged 60 or older. Those women exposed before reproductive age had reduced fecundability and higher risk of infertility. They also had reduced menstrual cycle length. Among Yucheng men, increased percent of oligospermia, reduced sperm capability of penetrating oocytes were observed. In addition, they gave birth to reduced percent of male offspring for 10 years. A follow-up 30 years after the event showed poorer health related quality of life as compared to unexposed people.
　　 Because of the long biological half-lives of PCBs and PCDFs, Yucheng women gave birth to children when significant internal levels of these chemicals were still present. The Yucheng children were thus prenatally exposed to these chemicals. Their gestational age-adjusted birth weight was reduced. Delay in growth continued to be observed in Yucheng children. The developmental milestones were achieved later among Yucheng children than controls. Neuro-cognitive scores were poorer among Yucheng children as compared to a well-matched neighborhood reference at ages 1~2.5 yr by the Bayley Scale of Infant Development, at ages 4~5 by Stanford-Binet test, and at ages 6~7 by the Wechsler Intelligence Scale for Children, Revised. Visual-spatial ability were especially affected in Yucheng boys noted by Raven’s Progressive Matrices at 6~8 yr of age. Yucheng children had more behavioral problems compared to reference children from age 7~14 yr as scored by their mothers with the Achenbach Child Behavior Checklist and the Rutter Child Behavior Scale A. The Yucheng children had increased rates of pigmented or dystrophic nails, acne scars, and hyperpigmentation at 8~12 yr of age. The main nail findings were transverse coarse grooves and irregularly concaved depression in approximately 33% of children, with predilection for thumbs, followed by big toes and other fingers. Yucheng children had significantly higher percentage of congenitally missing teeth (29% vs. 2.7%) or rotation in teeth (19% vs. 2.7%) as compared to the controls. The percentages of developmental defects increased significantly with increasing maternal serum PCB levels, children PCB and PCDF levels, and duration of breast milk feeding. The Yucheng children had a history of more frequent bronchitis, upper respiratory infection, and ear infections as reported by the parents in 1985 and 1992. Otolaryngological examination done in 1992 showed increased otitis media and its chronic complications in Yucheng children as compared with their controls. The middle ear findings were found to be associated with children’s serum levels of PCDFs, but not PCBs, suggesting a stronger immunological effects of PCDFs than PCBs. In 2007, the Yucheng children were found to have poorer hearing comparing to their neighbors. Among the second generation young men born to PCB/PCDF-exposed mothers, semen analysis was also performed when they were 16-21 years of age. Increased percentage of abnormal morphology, reduced percentage of mobile sperm, and reduced capability of sperm penetrating Chinese hamster oocytes were found. Hormonally, there was a decrease of serum testosterone levels and increase of serum follicle-stimulating hormone (FSH) levels in Yucheng boys at the age of puberty as compared with reference group.
　　 We conclude that exposure to food contaminants PCBs and PCDFs caused rather significant health effects, including directly exposed and children born to exposed mothers. Such health effects are observable even 30 years after the exposure event.