Study: Most Plastics Leach Hormone-Like Chemicals
Most plastic products, from sippy cups to food wraps, can release chemicals that act like the sex hormone estrogen, according to a study in Environmental Health Perspectives.
The study found these chemicals even in products that didn't contain BPA, a compound in certain plastics that's been widely criticized because it mimics estrogen.
Many plastic products are now marketed as BPA-free, and manufacturers have begun substituting other chemicals whose effects aren't as well known.
Exactly how BPA affects humans, and how serious its effects are, are still very much up for debate. The U.S. government generally advocates caution and more research, but agencies have issued a range of hesitant warnings. The National Toxicology Program, a division of the National Institutes of Health, says it has "some concern" about potential BPA exposures to the brains and prostate glands of fetuses, infants and children. Other agencies say they have lingering, unresolved "questions" about the chemical.
Those questions largely circle around how prolonged exposure to the chemical in childhood or adulthood could affect reproduction and growth; how low-dose exposure at sensitive developmental stages could affect children and babies later in life; and how parental exposure could affect the next generation. Studies have shown links between BPA and cancer, diabetes, heart disease, and a host of other illnesses.
One major sticking point for scientists is the challenge of drawing conclusions from hundreds of studies, each using different animals (mice and rats among them), doses, and routes of exposure. As the Environmental Protection Agency has noted, "there is controversy about whether effects seen at lower doses in animals are meaningful and relevant to humans." And scientists have also wondered whether rodents are more sensitive to the chemical than us because they metabolize it differently.
Last year, the NIH launched a new round of studies, all with the same methodology, designed to answer the some of the niggling questions and help the government provide clearer guidance than it's been able to so far.
-- Eliza Barclay
But it's still unclear whether people are being harmed by BPA or any other so-called estrogenic chemicals in plastics. Most studies of health effects have been done in mice and rats.
The new study doesn't look at health risks. It simply asks whether common plastic products release estrogen-like chemicals other than BPA.
The researchers bought more than 450 plastic items from stores including Walmart and Whole Foods. They chose products designed to come in contact with food — things like baby bottles, deli packaging and flexible bags, says George Bittner, one of the study's authors and a professor of biology at the University of Texas, Austin.
Then CertiChem, a testing company founded by Bittner, chopped up pieces of each product and soaked them in either saltwater or alcohol to see what came out.
The testing showed that more than 70 percent of the products released chemicals that acted like estrogen. And that was before they exposed the stuff to real-world conditions: simulated sunlight, dishwashing and microwaving, Bittner says.
"Then, you greatly increase the probability that you're going to get chemicals having estrogenic activity released," he says, adding that more than 95 percent of the products tested positive after undergoing this sort of stress.
But what about all those products marketed as BPA-free? That's a claim being made for everything from dog bowls to bento boxes these days.
The team concentrated on BPA-free baby bottles and water bottles, Bittner says, "and all of them released chemicals having estrogenic activity." Sometimes the BPA-free products had even more activity than products known to contain BPA.
The testing didn't show which chemicals are to blame, which is likely to be frustrating to manufacturers.
But Bittner says consumers should be encouraged that at least some plastic products had no estrogen-like activity. He says that shows it is possible to make these products.
Early reaction to the study was mixed. Some scientists wondered about the test's reliability. Others noted that wine and many vegetables also can act like estrogen. And a few observed that Bittner has a financial interest in the testing lab and in a company involved in making plastic products that don't release estrogenic chemicals.
On the other hand, groups that have warned about the potential dangers of BPA in the past seemed to welcome the new research.
"This is really helpful because they took a look at very common products," says Sonya Lunder, a senior analyst at the Environmental Working Group.
But the results suggest that concerns about plastics can't be solved by worried consumers at the checkout counter, Lunder says. It's a problem for government, she says.
"Regulatory agencies need to study the effect of chemicals leaching out of plastic," Lunder says, adding that an EPA program formed more than a decade ago to do this sort of research still hasn't produced many results.
Until scientists come up with more definitive answers, Lunder says, worried consumers can follow the old advice to avoid putting those baby bottles and other plastic products in dishwashers or microwaves.
"We've long cautioned consumers to avoid extreme heat and cooling for plastics, to discard scratched and worn plastics and we feel like this [study] validates one of our many concerns," she says.
MICHELE NORRIS, host:
Many of you have been clearing your house of baby bottles and other plastic products because they're made with the chemical BPA. Research has shown that BPA can act like the hormone estrogen, at least in mice and in rats.
Now, as NPR's Jon Hamilton reports, a new study finds that even plastics without BPA can release estrogen-like chemicals.
JON HAMILTON: Before you toss out your Tupperware, it's worth noting that scientists still don't know whether people are harmed by any of the chemicals coming from plastics. It's just not clear. And the new study doesn't look at health risks. It simply asks whether common plastic products release estrogen-like chemicals other than BPA.
That's something George Bittner, a biologist at the University of Texas in Austin, had been wondering for a long time. So he sent a research team to stores, including Wal-Mart and Whole Foods. Their mission: buy a whole bunch of stuff made of plastic, the kind of stuff that might come in contact with food.
Mr. GEORGE BITTNER (Biologist, University of Texas at Austin): Baby bottles, deli packaging, flexible bags.
HAMILTON: The team came back with more than 450 products. Then CertiChem, a testing company that Bittner founded, chopped up pieces of each product and soaked them in either salt water or alcohol to see what leeched out. Bittner says the tests made one thing clear.
Mr. BITTNER: Most plastic products on the market today release chemicals having easily detectible estrogenic activity.
HAMILTON: Estrogenic activity means they act like estrogen. Bittner says about 70 percent of the stuff the lab tested released these chemicals, and Bittner says that was before they exposed the stuff to real-world conditions: simulated sunlight, dishwashing and microwaving.
Mr. BITTNER: Then, you greatly increase the probability that you're going to get chemicals having estrogenic activity released, in fact, maybe somewhere between 95 to 98 percent.
HAMILTON: But what about all those things marketed as BPA-free - you know, dog bowls, bento boxes?
Mr. BITTNER: In particular, we've concentrated on baby bottles and water bottles. We've tested them and all of them released chemicals having estrogenic activity.
HAMILTON: Sometimes even more than products known to contain BPA. The testing didn't show which chemicals are to blame. That's likely to be frustrating to manufacturers, but Bittner says consumers should be encouraged that at least some plastic products had no estrogen-like activity. He says that shows it can be done.
Early reaction to the study was mixed. Some scientists wondered about the test's reliability. Others noted that wine and many vegetables also have estrogenic activity. And they note that Bittner has a financial interest in the testing lab and in a plastics company.
But groups that have warned about BPA in the past seemed to welcome the new research.
Ms. SONYA LUNDER (Senior Analyst, Environmental Working Group): This is really helpful because they took a look at very common products.
HAMILTON: Sonya Lunder is from the Environmental Working Group. She says the results suggest the concerns about plastics can't be solved by worried consumers at the checkout counter. It's a problem for government.
Ms. LUNDER: Regulatory agencies like the FDA need to study the effect of chemicals leeching out of plastic. We know the EPA first proposed its hormone disrupter screening program 15 years ago and has made virtually no progress.
HAMILTON: Lunder says that until there are more definitive answers, worried consumers can follow the old advice to avoid putting those baby bottles in dishwashers or microwaves.
Ms. LUNDER: See, we've long cautioned consumers to avoid extreme heat and cooling for plastics, to discard scratched and worn plastics, and we feel like this validates one of our many concerns.
HAMILTON: The new study appears in the online edition of the journal Environmental Health Perspectives.
Jon Hamilton, NPR News. Transcript provided by NPR, Copyright NPR.