The finding contradicts conclusions reached by a wide range of bisphenol-a researchers as well as those of another federal panel, which generally agree the chemical disrupts key reproductive and developmental systems and is linked to such disorders as cystic fibroids, reduced sperm quality and recurrent miscarriages.
The finding, by a group of 12 independent scientists convened by the National Toxicology Program to assess bisphenol-a's potential reproductive and developmental hazards, was also denounced by activists as error prone and industry influenced.
"Only the chemical industry agrees with the decision that (bisphenol-a) has little or no human health risks. That by itself should speak volumes about the corrupted process endorsed by the panel today," said Anila Jacob, a senior scientist with the Environmental Working Group.
The group earlier this year discovered that a contractor compiling data for the panel also worked for plastics manufacturers; the review was halted and the contractor dismissed, but the agency reported no improprieties.
Bisphenol-a is ubiquitous in modern life, used to line food cans to preserve shelf life and to make plastic baby and sports bottles shatterproof. It also contaminates our bodies, although at concentrations so minute -- from less than 1 part-per-billion to about 5 parts-per-billion for most of us -- that scientists could barely detect it a decade ago.
In the past few years, researchers studying laboratory animals have found bisphenol-a acts like a hormone at far lower levels, scrambling chromosomes and impairing reproductive health, particularly in the very young.
But the chemical is rapidly rendered harmless in the human digestive system. And industry has long argued that studies showing harm do so by injecting bisphenol-a directly into animals -- an exposure, they say, with no real-world analogue.
The federal panel agreed, considering in their assessment only studies where the compound was fed to laboratory animals.
"This was a very reassuring conclusion," said Steve Hentges, director of the American Plastics Council's polycarbonate business unit. "The issue will continue. More research will be done. But right now what this tells us is the weight of scientific evidence doesn't find much of a concern."
The findings go out for public comment, will be assessed by the National Toxicology Program, and then be submitted for peer review before becoming the agency's policy recommendation. That recommendation is used by federal and state regulatory agencies when setting exposure recommendations and limits. Europe and Japan have undergone similar reviews recently, both concluding bisphenol-a does not pose much of a threat at current levels.
What Wednesday's report will not likely do, added Michael Shelby, director of the NTP's Center for the Evaluation of Risks to Human Reproduction, is end the debate on the safety of bisphenol-a.
"The problem is not because we didn't try to settle it," he said, "but because the nature of the scientific evidence available to the panel doesn't particularly allow them to do that.
"This is a pretty heavy-duty scientific document. For the lay person to get any clear messages, it probably is not going to be easy.
"Nonetheless, (based on) the conclusions reached by this panel, I would say their concerns are moderate to low."
Contact Douglas Fischer at email@example.com or (510) 208-6425.