Intrauterine exposure to environmental toxins: The significance of subtle behavioral effects

Abstract

Recently, there has been an increase in interest in subtle effects associated with exposure to environmental toxins. One methodological problem in research in this area involves assessment of degree of contamination when exposure occurs at low and moderate levels. A second problem lies in determining the clinical or practical significance of subtle toxic effects when they are observed. Both these issues are illustrated by the case of polychlorinated bi‐phenyls (PCBs), a family of environmental toxins found in moderate concentrations in humans who consume Lake Michigan sports fish. Two hundred forty‐two newborns whose mothers had consumed these fish and 71 newborns whose mothers had abstained were examined in the immediate post‐partum period. Degree of exposure was measured by both maternal contaminated fish consumption and cord serum PCB level. An examination of the data suggests that, at the levels of exposure found in this sample, a maternal report may in some instances be more sensitive and reliable than a biochemical analysis. While statistically significant effects on birth size, gestational age, and neonatal behavior were observed, the clinical significance of these effects is not yet known since none of the exposed infants weighed less than 1500 g and criteria for newborn behavioral adequacy have not been established. However, research on other toxic substances suggests that subtle neonatal deficits frequently signal the existence of an ongoing toxic process with clinically significant implications for later development.