A surprising study by the National Institute of Environmental Health Sciences reveals that a mother's background exposure to DDE (a product of the insecticide DDT) and PCBs (a once widely used, but now banned liquid electrical insulator) may increase the size of her children at puberty.
The study, appearing in the Journal of Pediatrics (April 2000, Vol. 136, pp. 490-496) followed up the teen children of women whose blood and milk levels of PCBs and DDE samples had been measured by NIEHS in a North Carolina Infant Feeding Study of expectant and new mothers between 1978 and 1982.
Height of boys at puberty, and their weight adjusted for height, increased with higher prenatal exposure to DDE. Girls with the highest prenatal PCB exposures were heavier for their heights than other girls, but this result was statistically significant only in white girls.
Since DDE and PCBs are widely present in the environment, essentially all pregnant women have some background level of these chemicals in their blood and milk. This study used a combined index of milk and blood samples taken immediately before and at intervals after birth to estimate the child's exposure.
"The results were surprising, but do not provide a completely clear picture of the effects of these pollutants," Beth C. Gladen, Ph.D., first author on the study, said.
"We do not know how the chemical exposures might produce these changes, but there is still laboratory work going on here and elsewhere that may help explain it." Both DDE and PCBs are known to be hormonally active.
Dr. Gladen's co-authors were N. Beth Ragan, and Walter Rogan, M.D., both also of NIEHS.
The children's weight was related only to their chemical exposure prenatally. There were no effects shown in those exposed through breast feeding and no effect on the ages at which pubertal stages were attained as established through questionnaires filled out by children and/or parents.
Out of a group of about 850 participants in the original North Carolina Infant Feeding Study, 594 families participated in the puberty study.