By Janet Raloff
BOSTON — The ubiquity of the pollutant bisphenol A in many plastic products, food-can linings, cash-register receipts and dental resins means that everyone is exposed to it daily. But controversy remains about how much BPA people actually ingest or otherwise encounter. New data reported at a February 16 symposium raised red flags over the accuracy of previously reported human blood concentrations of BPA — amounts described over the years as being representative of the general population.
Those values appear to be roughly 1,000 times higher than most people actually encounter, concludes toxicologist and symposium organizer Justin Teeguarden of the Pacific Northwest National Laboratory in Richland, Wash. His assessment, reported at the American Association for the Advancement of Science annual meeting, was based on a reanalysis of data from previously published studies, including BPA values measured in more than 30,000 people.
Animal and human studies have linked exposures to BPA, a hormone mimic, with cardiovascular changes, altered behavior in children, prediabetic symptoms and reproductive impairments. So getting estimates of typical exposure right, Teeguarden said, is crucial to defining what intake levels should now be probed intensively by toxicity testing.
In addition to Teeguarden’s work, toxicologist K. Barry Delclos of the Food and Drug Administration’s National Center for Toxicological Research in Jefferson, Ark., described experiments in which rodents received seven doses of BPA daily from conception through birth and on into early adulthood. Amounts ranged from very low (2.5 micrograms per kilogram of body weight, in the range of probable human exposure) to doses more than 100 times higher.