Washington BPA - a chemical used in food containers - is so widespread that most people have traces of it in their bodies.
But health officials can't decide if that's a problem, or something we all can live with.
Bisphenol A is useful for hardening plastics to make all sorts of consumer products, from CDs to baby bottles. And the canning industry uses it for coatings that prevent leaks and bacterial contamination in metal food containers.
Some scientists are concerned that BPA could be harmful, since it mimics some of the effects of a powerful hormone, estrogen. Infants may be particularly vulnerable because their bodies are developing and cannot eliminate the chemical as quickly.
Earlier this year, the Food and Drug Administration issued a scientific assessment that BPA is safe and asked independent scientists to review its conclusion. That report - made public Tuesday - found that the FDA's science was badly flawed. The FDA did not consider all the evidence and its margin of safety for human exposure to BPA could be off by a factor of ten times or more, the outside scientists said.
While the experts sort out the issue, what are the options for worried consumers? Here are some questions and answers:
Q: It sounds like BPA is everywhere; how can people avoid it?
A: "Get to know your plastics," says Urvashi Rangan, a senior scientist with Consumers Union, which publishes Consumer Reports. Avoid polycarbonate plastic containers, those imprinted with the recycling number "7" and the letters "PC." Don't microwave foods in these containers. Don't use polycarbonate plastic baby bottles. Consider powdered infant formula instead of liquid formula in cans. Cut down on canned foods.
"If you the consumer want to take matters into your own hands while the science is being sorted out here, those are the things you can do that will directly reduce your level of exposure to BPA," said Rangan.
One thing mothers should not do is stop giving their infants proper nutrition because of fears about BPA, says acting Surgeon General Steven Galson. "While the best source of nutrition for babies is the mother's breast milk, infant formula remains the recommended alternative when breast milk is not an option," he said.
Q: Wait a minute, aren't some people overreacting here? Has anybody died from BPA?
A: No direct cause-and-effect relationship has been established to show that exposure to small amounts of BPA harms people.
But many scientific studies have raised that possibility, and some government scientists believe it should not be dismissed lightly. Chemical exposures that cause harm over a long time are hard to detect.
The National Toxicology Program conducted its own BPA assessment earlier this year, and differed with the FDA. The toxicology program found "some concern" for BPA effects on the brain, behavior and prostate gland in fetuses, infants and children at current exposure levels. "Some concern" is right in the middle of the toxicologists' five-level scale for ranking the possible harmful effects of chemicals.
The independent panel that reviewed the FDA's assessment said the agency needs to go back and take a second look at several studies it earlier dismissed.
Q: What's going to happen now?
A: On Friday, the FDA's Science Board will meet to discuss the controversy in public. It was a subcommittee of the Science Board that issued the report criticizing FDA's safety analysis. But FDA officials say it could take two to five years to complete additional research and reach a final conclusion.
If scientific evidence against BPA mounts and U.S. regulators don't act, Congress may try to restrict some uses for the chemical.
"If FDA continues to dismiss independent scientific evaluations of BPA, correcting the issue legislatively is an option," said Rep. Rosa DeLauro, D-Conn., chairwoman of a committee with jurisdiction over the FDA budget.
Q: What would be the downside of just banning BPA altogether?
A: The canning industry thinks there would be unintended consequences. The chemical is used to make epoxy resins that coat and seal the inside of cans. That prevents leaks and keeps bacteria from contaminating the foods inside.
"Although we are looking for alternatives, they are not readily available, and there is no 'drop-in' replacement for these uses," said John Rost, chairman of the North American Metal Packaging Alliance, a trade group. "Quick changes that have not been evaluated could impact the real safety issue: food poisoning."
Short of a ban on all BPA in food containers, Canada has banned it in baby bottles as a precaution.