Editorial: Ongoing Talks on BPA

FDA may support “reasonable steps” to decrease exposure to bisphenol A (BPA)-but when it comes to banning the chemical outright, the agency isn’t quite ready to go there.

On March 30, FDA rejected a 2008 citizens’ petition from the Natural Resources Defense Council (NRDC) to ban BPA in human food and food packaging. BPA touches the lives of millions and is present in more than 90% of humans, says  Bryan Walsh, who wrote an article in Time magazine titled “Why the FDA Hasn’t Banned Potentially Toxic BPA (Yet).”

In fact, Walsh cites CDC estimates that “Americans have traces of 212 environmental chemicals in their bodies-including so-called endocrine disruptors like bisphenol A (BPA), which may have a major impact on human health even though the dose is barely perceptible.”

Science is at a state in which we can detect minute presences of chemicals. “But,” Walsh continues, “our ability to detect chemicals outpaces our ability to understand exactly what exposure means for us-which puts regulatory agencies in a tight spot, especially when the chemicals in question are widely used in modern life and are hard to replace.”

While some claim overwhelming evidence of detrimental effects, others, including FDA, say that the science is still inconclusive on whether our exposure to BPA-FDA estimates this to be 0.1 to 0.2 µg per kg of body weight daily for adults-is enough to cause harm.

Many feel even a hint of potential harm is reason enough to ban BPA entirely. I’m not even close to being an expert on BPA or the science to go out on a limb one way or the other. But I think it worth mentioning that to toxicologists, there is a difference between a “no effect” level (a dose at which there is absolutely no effect) and a “no adverse effect” level.

“Toxicologists are trending towards ‘no adverse effect’ level type of statements because [they] more realistically describe the situation,” says George A. Burdock, PhD, president of toxicology consultant Burdock Group.

The situation is that all substances have the potential to produce change, and change can be positive or negative at certain doses. “Even water has an adverse effect,” says Burdock. “Five or so liters within a few hours can be fatal, even though water is ‘organic’ and ‘natural.’” (Many also like to quote Paracelsus, who said, “The dose makes the poison.”)

“Most anything can produce a change in the body, and analytical methods are constantly improving such that now even the smallest change is detectable. The question is, is the change meaningful?” Burdock asks. “There is, in most circumstances, a threshold below which no adverse effects can be demonstrated; it is just that sometimes, it is not possible to determine at what dose that threshold exists.”

Because all substances have the potential to be toxic, FDA generally abides by the “no adverse effect” rule. And FDA says the science thus far is not conclusive enough to determine if there is an adverse effect of BPA at the levels at which humans are typically exposed.

In its response to NRDC, the agency struck down many of the petition’s supportive studies, stating that many of the studies done on animals-and the doses and dosage methods (e.g., subcutaneous instead of oral)-are not necessarily relevant to how humans are exposed to BPA. On its webpage on BPA, FDA states, “Overall, the current literature cannot yet be fully interpreted for biological or experimental consistency or for relevance to human health. Part of the difficulty for evaluating consistency lies in reconciling findings of different studies that use different experimental designs and different specific behavioral tests to measure the same dimension of behavior.”

Burdock says, “In terms of BPA, people need to examine the facts. Is the test model and exposure realistic and applicable to whole animals? Is the effect ‘real’ or anecdotal? Is there a real effect to humans or just a hypothesis based on minimalistic observations of in vitro test systems, with generous extrapolation via speculation about what ‘could’ happen? Is the effect real and reproducible, or just junk science?”

FDA emphasizes that its evaluation of BPA and dose toxicity is ongoing. Also, on its BPA webpage, FDA says it is “taking reasonable steps to reduce human exposure to BPA in the food supply.” This includes “supporting industry actions” to end BPA-containing baby bottles and “supporting efforts” to replace or reduce the use of BPA in food cans.

FDA’s not the only one looking at this issue. Across the pond, the European Food Safety Authority is holding a June meeting during which scientists will debate low-dose responses for chemicals such as BPA. Stay tuned.