Objective: To compare the cognitive development in Taiwanese children who had been exposed prenatally to high levels of heat-degraded polychlorinated biphenyls (PCBs) with control children who were exposed to background levels. The disorder was called Yu-Cheng, "oil disease," in Taiwan.
Design: Matched-pair cohort study.
Setting: Communities in central Taiwan in which there had been a cooking-oil contamination and mass poisoning by heat-degraded PCBs in 1978 through 1979.
Participants: One hundred eighteen children born between June 1978 and March 1985 during or after their mothers' consumption of contaminated rice oil; 118 children matched for age, sex, neighborhood, maternal age, and parental education and occupational class; and 15 older siblings of exposed children, born before the poisoning.
Main outcome measures: Cognitive development measured from 1985 through 1990 using the Chinese versions of the Stanford-Binet test and the Wechsler Intelligence Scale for Children, Revised,
Results: The exposed children scored approximately 5 points lower on the Stanford-Binet test at the ages of 4 and 5 years and approximately 5 points lower on the Wechsler Intelligence Scale for Children, Revised, at the ages of 6 and 7 years. Children born up to 6 years after their mothers' exposure were as affected as children born within a year or two after exposure when examined at 6 and 7 years of age. Older siblings resembled the control children.
Conclusion: Children prenatally exposed to heat-degraded PCBs had poorer cognitive development than their matched controls. The effect persisted in the children up to the age of 7 years, and children born long after the exposure were still affected.