Last Friday, I blogged that the U.S. Food and Drug Administration (FDA) was expected to rule on the safety of bisphenol-A (BPA) for use in various plastics including the plastic liners in canned food and drink containers. The Natural Resources Defense Council lobbying group has been pressing the agency for several years to ban the substance claiming that it produces deleterious estrogenic effects in the human body.
The FDA has declined to ban BPA. The agency reportedly sent a letter to the NRDC stating:
"The information provided in your petition was not sufficient to persuade FDA, at this time, to initiate rulemaking to prohibit the use of BPA in human food and food packaging."
The agency based its decision on recent research that found:
With the support of the National Institute of Environmental Health Sciences (NIEHS) and the National Toxicology Program (NTP), scientists at FDA's National Center for Toxicological Research (NCTR) have been studying BPA.
The NCTR researchers have been conducting in-depth studies of BPA since September 2008, when a report by the NIEHS and NTP called for more research into the potential toxic effects of BPA on fetuses, infants and children.
NCTR's findings include:
- The level of BPA from food that could be passed from pregnant mothers to the fetus is so low that it could not be measured. Researchers fed pregnant rodents 100 to 1,000 times more BPA than people are exposed to through food, and could not detect the active form of BPA in the fetus eight hours after the mother's exposure.
- Exposure to BPA in human infants is from 84 to 92 percent less than previously estimated.
NCTR researchers report that they were able to build mathematical models of what happens to BPA once it's in the human body. These models showed that BPA is rapidly metabolized and eliminated through feces and urine. They found that BPA is "exactly the opposite" from some other toxins, like dioxin, that can stay in the body's tissues for months or even years.
The center's toxicology research has not found evidence of BPA toxicity at low doses in rodent studies, including doses that are still above human exposure levels.
Naturally, the environmental lobbyists disagreed. Businessweek reports:
Sarah Janssen, a senior scientist at the NRDC, said the FDA's denial of a ban shows "a major overhaul" of chemical regulation is needed. The Environmental Working Group, a Washington-based advocacy group, said consumers can no longer trust the FDA to protect the health of their families.
"The agency has veered dangerously off course," Jane Houlihan, the group's senior vice president for research, said today in a statement. "Pregnant women and new parents should no longer think FDA has their backs."
Hundreds of studies focusing on the effects (or in this case mostly non-effects) of trace amounts of BPA ingested by people have been conducted. Unfortunately, the uncertainties inherent in this kind of scientific research means that the proponents of the precautionary principle can always justify (at least to themselves) their continuing campaign to ban BPA.