A cohort study of behavioral problems and intelligence in children with high prenatal polychlorinated biphenyl exposure

Background: In 1978, about 2000 persons in Taiwan were poisoned when their cooking oil was contaminated during Manufacture with heat-degraded polychlorinated biphenyls, which are toxic, very widespread pollutant chemicals. The chemicals cannot be metabolized or excreted, and 8 of the first 39 children born to affected women died. When examined in 1985, 117 surviving children were found to have ectodermal defects, developmental delay, and disordered behavior. We have continued to observe the children. Methods: From 1992 through 1995, 118 children born between 1978 and 1985 (during or after their mothers' exposure) and 118 matched neighborhood control children had cognitive function measured yearly with the Wechsler Intelligence Scale for Children-Revised and behavioral problems measured with the Achenbach Child Behavior Checklist and the Rutter Child Behavior Scale A. Results: The exposed children scored 3 points (P=.05) lower than control children for IQ; 3 points (P=.002) higher on the Child Behavior Checklist (an effect size similar to the sex difference); and 6 points (P<.001) higher on the Rutter scale (3 times the sex difference). Birth year x exposure interactions, testing whether children born long after the exposure were as affected as those born soon after, were small and not significant. Age x exposure interactions, testing whether the children improved relative to control children as they got older, were significant only for the Rutter scale. Conclusions: Prenatal exposure to these compounds produces long-lasting cognitive and behavioral damage, but there is some evidence of recovery.