Starting Wednesday, grocery stores across California must post signs in their check-out areas notifying customers that bisphenol A - BPA - is in some food and drink containers. The notices are required under Prop. 65, because the state has determined that BPA causes "harm to the female reproductive system."
But does it?
That's still a matter of debate.
Very small amounts of BPA - used to strengthen the lining of cans and bottles - can migrate into food or beverages. Some studies have found that exposure to high levels of the chemical has damaged the fetuses of lab animals. There is also research that has linked it to disruptions to the body's hormonal system.
But the federal Food and Drug Administration has determined that the chemical is safe as it is currently used.
The agency says its experts in toxicology, analytical chemistry, endocrinology, epidemiology and other fields completed a four-year review in 2014 of more than 300 scientific studies, and they did not find "any information ... to prompt a revision of FDA's safety assessment of BPA in food packaging at this time."
BPA used to be in baby battles and sippy cups, but manufacturers abandoned it several years ago in the face of widespread public concern about possible negative health effects. The FDA subsequently banned it from those products in 2012, although the agency said at the time that it did so not because it believed BPA was unsafe, but to codify what the industry had already done.
California's Office of Environmental Health Hazard Assessment added BPA to the Prop. 65 list on the recommendation of a panel of scientific experts.
But the agency posts this caveat on its website:
A Proposition 65 warning is not a regulatory decision that a product is safe or unsafe. Rather, the law is designed to help consumers decide whether to assume the risks of purchasing particular products that result in exposures to listed chemicals.
Here is the language Health Hazard Assessment suggests stores use for their BPA notices:
WARNING - Many food and beverage cans have linings containing bisphenol A (BPA), a chemical known to the State of California to cause harm to the female reproductive system. Jar lids and bottle caps may also contain BPA. You can be exposed to BPA when you consume foods or beverages packaged in these containers. For more information, go to: www.p65warnings.ca.gov/chemicals/bisphenol-bpa
Typically, if a chemical is on the Prop. 65 list, the manufacturer must place a warning directly on the products that contain it.
But in the case of BPA, Health Hazard Assessment said it did not have enough information to determine how much BPA in a product should trigger a warning.
So the agency secured approval for an emergency regulation that allows stores to place a warning at cash registers until Health Hazard Assessment determines which level of the chemical should require a Prop. 65 label. The agency says it hopes to complete that process within a year.
Some food companies, such as Amy's Kitchen and Annie's Homegrown, owned by General Mills, already use BPA-free cans. And other companies are moving in that direction, too. Campbell's Soup announced in March that it plans to be BPA-free by the middle of next year. The company, which makes two billion cans a year, says it will use acrylic or polyester material in can liners as a substitute.
Ash Daniels, the manager of a General Discount store in Compton, said he would be putting up the warning signs at every cash register Wednesday.
He said he would prefer to put them by the products that contain BPA, as he believes that would provide the store better protection in terms of liability.
At a Food for Less in Huntington Park, the supervisor - who declined to give his name - said he was unaware that the signs needed to go up starting Wednesday.
Claudia Diaz of South L.A. brought her five-year-old son with her to the store to buy a can of evaporated milk.
She said having a BPA warning at the cash register is too late, that it should be on the can.
"I’m not paying attention once I’m done shopping, especially with kids," she said. "At the register, my focus is on something else, not on what I picked out."
But the signs will only be in store check-out areas for about a year, until the state figures out which cans and bottles should carry a BPA warning label.
This story has been updated to correct the URL for the state's BPA information page, to clarify that the signs will be in check-out areas for about a year, and to clarify that the warning sign is not "generic."