Cognitive development of children prenatally exposed to polychlorinated biphenyls (Yu-Cheng children) and their siblings.

An intoxication episode resulting from rice-bran oil (Yu-Cheng) contaminated with polychlorinated biphenyls (PCBs) occurred in Taiwan from 1978 to 1979. After that episode, the authors found 15 Yu-Cheng children who were born to intoxicated mothers after their documented consumption of PCB-contaminated oil; these children had older siblings, born before PCB exposure, without prenatal PCB exposure. The cognitive development of these Yu-Cheng children and the youngest of their elder siblings were assessed annually from 1985 to 1990 using the Chinese version of the Wechsler Intelligence Scale for Children, Revised Version (WISC-R) for those over six years of age. Compared with their elder siblings, the Yu-Cheng children scored significantly lower (p < 0.05) on the verbal intelligence quotient, by 6.8-16.1 points; on performance IQ by 10.2-18.4 points; and on full-scale IQ by 8.9-18.5 points, during the six measurements performed from 1985 to 1990. The differences in WISC-R IQ scores between the two groups have remained unchanged during these six years of follow-up.