Breast milk: a leading source of PCBs.

Exposure to polychlorinated biphenyls (PCBs)--oily compounds that have been used as lubricants and insulating fluids--can diminish a child's ability to learn (SN: 11/11/95, p. 310). A new Dutch study now indicates that Rotterdam preschoolers who were breast-fed during infancy possess 3.6 times as much of these neurotoxic chemicals in their blood plasma as do children who had been fed infant formula only.

The study followed 173 children, slightly more than half of whom had been breast-fed as infants (usually for more than 3 months). By 42 months of age, all the children carried at least some PCBs in their blood. While prenatal exposures and childhood diet contributed some PCBs, breast milk proved the richest source, Svati Patandin of Sophia Children's Hospital in Rotterdam and her colleagues report in the October American Journal of Public Health. In fact, their data suggest that while the breast-fed infants were nursing, PCB concentrations in their blood "must have reached levels as high as their mothers'."

"To our knowledge," they observe, "no other study has measured plasma PCB levels in children--either formula-fed or breast-fed during infancy--in relation to environmental exposures to PCBs."

While many earlier studies attempted to quantify childhood exposure overall to the 209 PCBs, the Dutch researchers focused on just four representatives of this family of related chemicals. As such, notes Corine Koopman-Esseboom, a coauthor at Sophia Children's Hospital, it's hard to directly compare the Rotterdam exposures to those reported for U.S. populations. However, she says, the Dutch exposures "would appear comparable" to those linked with IQ deficits in Detroit youngsters last year (SN: 9/14/96, p. 165).

Koopman-Esseboom administered developmental tests to the Rotterdam infants at ages 3, 10, and 18 months. While the breast-fed babies had poorer muscle tone than the bottle-fed infants--something that she says was also seen in the PCB-exposed Detroit children--the Dutch youngsters exhibited no mental delays when compared to formula-fed peers. However, she notes that unpublished data from a follow-up looking for IQ deficits in the Dutch preschoolers "did find something."

The solution, she and her coauthors argue, is not to forgo breast-feeding but to lower PCB concentrations in the food chain so mothers accumulate less in their milk.