Polychlorinated biphenyls in umbilical cord serum of newborns from Rio Grande do Sul state, Brazil.

Background: Polychlorinated biphenyls (PCBs) are food-chain contaminants that have been shown to contaminate foods worldwide. The newborn are exposed to these organochlorine compounds across the placenta and through breastfeeding. They are proven to be carcinogenic and may contribute to congenital malformation etiology.