A panel of U.S. government researchers trying to answer the controversial question of whether a key building block of polycarbonate can interfere with hormone systems essentially has decided that the evidence points both ways.
The panel from the National Toxicology Program in Research Triangle Park, N.C., announced May 14 that it found "credible evidence" that very low doses of bisphenol A can do things like enlarge prostate glands and hasten puberty in rats and mice.
But the panel also found that studies that came to the exact opposite conclusion were "credible." It said it is not endorsing the idea that BPA is dangerous at low levels.
The panel said it "is not persuaded that a low-dose effect of BPA has been conclusively established as a general or reproducible finding."
The debate has clear implications for polycarbonate: If BPA is found to interfere with hormone systems at much lower doses than previously thought, that could increase pressure to phase out PC in some applications.
Steve Hentges, executive director of the polycarbonate business unit of the American Plastics Council in Arlington, Va., said it is not clear that even if the effects occur, they are harmful. And he said the panel noted the importance of some large, multigenerational studies that found no harm.
The panel said those studies were "especially noteworthy" because of their "considerable strength and statistical power."
"We believe the overwhelming weight of the evidence shows there is no concern about health effects of BPA at low doses," Hentges said.
The NTP panel recommended additional studies, and Hentges said some of those are under way.