Narrator: This is Science Today. Mothers who have been exposed to high levels of a specific class of the toxicant PCBs – known as non-coplanar PCBs – may want to think twice before breastfeeding their infants. A study by University of California, San Francisco has found that rat pups exposed to similar levels of these PCBs in their bloodstream had significant developmental abnormalities.
Merzenich: For very good reason, more and more mothers are nursing their babies. The problem is that these chemicals are concentrated in breast milk at a level of about six-fold in breast milk as they are in the general body tissues because they are concentrated in fat.
Narrator: Neuroscientist Michael Merzenich, the senior author of the study, who has done extensive research on autism, suggests that women with an inherited weakness for developmental disorders may want to think about this possibility before breastfeeding.
Merzenich: So, if your family – or husband – has a history of language impairment or of dyslexia or of autism itself, it would be an indication that there's some reason for concern.
Narrator: For Science Today, I'm Larissa Branin.