JUDY WOODRUFF: Finally tonight, an update on a report we aired last fall about the possible dangers of a chemical found in plastic bottles. NewsHour correspondent Betty Ann Bowser has our Science Unit story.
BETTY ANN BOWSER, NewsHour Correspondent: A chemical found in hard plastic, commonly seen on the sidelines of sporting events, has become so controversial that Nalgene will no longer make water bottles out of it.
The Canadian government and at least one U.S. senator want to ban or limit its use. And a draft report by the National Toxicology Program acknowledged for the first time some concern that it may affect neural and behavioral development in fetuses, infants and children at current exposures.
Dr. John Bucher is the head of the National Toxicology Program.
JOHN BUCHER, Associate Director, National Toxicology Program: We have a little more confidence that this data is a little more solid than it was over the last year. And I think that, while we still have some issues related to understanding exactly what these early changes mean in relation to long-term health effects, and also certainly the extrapolation to human health effects, is another leap that we need to make.
But we are becoming a little more certain that there are some emerging trends in the literature that do support the level of concern that our folks have indicated in our draft documents.
BETTY ANN BOWSER: The chemical is Bisphenol A, or BPA. Even before the latest rash of BPA headlines, these mothers in Washington, D.C., were worried, because Parent magazine and two popular baby guides told them to stop using hard plastic baby bottles that contained the chemical.
HEIDI PARSONT: Some of the studies are so scary and some of them are inconclusive. And some of them just say, you know, they don’t really know. And so it’s hard to decide how to proceed in a day and age when everything is made of this.
KIM TRUCANO: I also saw that could be possible issues with the nervous system, and that worries me.
BPA very common ingredient
BETTY ANN BOWSER: BPA has been used for more than 30 years to make polycarbonate plastic products shatter-resistant and optically clear. Each year, six billion pounds are produced around the world.
Almost every food can on the shelves at American grocery stores is lined with a resin made from BPA to prevent the metal from breaking down and affecting the contents. BPA is also found in CDs, DVDs, eyeglasses, dental sealants, bike helmets, shin guards, and dinnerware.
It's so ubiquitous that the Centers for Disease Control said it found BPA in the urine of 95 percent of over 2,000 adults tested at random.
The American Chemical Council insists BPA is safe. Steven Hentges is in charge of Bisphenol A research for the group.
STEVEN HENTGES, Chief BPA Scientist, American Chemistry Council: I think the bottom line is our view is that Bisphenol A does not present a risk to human health, in particular at the very trace levels in which it would be found in consumer products.But it's not so much our view that's really important. Our view is consistent with the views of scientific and government bodies worldwide that have reviewed the science in recent years. Such reviews have been done many times, and those reviews generally support that conclusion that Bisphenol A is not a risk to human health.
Deemed harmful by some scientists
BETTY ANN BOWSER: But BPA got new attention in 2007 when 38 internationally recognized scientists said it was harmful.
In an unusual consensus statement, after looking at 700 different studies and after publishing their findings in six peer-reviewed papers, the scientists said adverse effects found in animals exposed to low doses of BPA gave them cause for "great concern" because of the "potential for similar adverse effects in humans."
Developmental reproductive biologist Rheta Newbod was in the group of 38.
RHETA NEWBOD, National Institute of Environmental Health Sciences: If we look at all these things that are -- illnesses that are going up in the United States, there's an increased incidence in breast cancer. There's an increased incidence in prostate cancer. We have more problems with infertility and fertility. We have problems with thyroids, the incidence of thyroids are going up.
So we have all of this information. We do not have the direct link to say that Bisphenol A is directly associated with these lesions. But there is reason for concern that BPA is actually playing a role in some of these.
BETTY ANN BOWSER: In her lab at the National Institute of Environmental Health Sciences, Newbod studied the effect of low-dose BPA on mice. She injected them just five days after they were born and then raised them normally for 18 months. After that, she studied their reproductive tracts.
RHETA NEWBOD: When they aged out, we found paraovarian cysts. And these are cysts that are located just outside of the oviduct.
Now, if you saw paraovarian cysts in a human, that would be associated with infertility or sub-fertility. In the mice, we also saw changes with cystic structures in the ovary.
BETTY ANN BOWSER: So what does all of this suggest for human beings?
RHETA NEWBOD: I think, for me, the data is very clear, using the animal models, that there is reason for concern.
No real consensus on toxicity
BETTY ANN BOWSER: Hentges says the American Chemistry Council rejected the group's conclusion.
STEVEN HENTGES: The position of the 38 scientists is distinctly at odds with the views of every other review of Bisphenol A that has been conducted in recent years.
In every other case, scientific and government bodies with open and transparent processes which very carefully managed conflicts of interest, in every case the conclusion from those reviews is that Bisphenol A is not a concern for human health.
BETTY ANN BOWSER: To make matters even more confusing, a group called together by the National Toxicology Program also reached conclusions different than the group of 38's. Environmental Protection Agency research toxicologist Earl Gray was a member of that panel.
EARL GRAY, Environmental Protection Agency Toxicologist: We have negligible concern for the ability of Bisphenol A to affect adult reproductive health. That was sort of the lowest level of concern.
The next level, we had minimal concern for its ability to affect the prostate and other tissues. And the only -- so that's a two out of a five scale level of conversation. The highest level of concern expressed by the panel, which is some concern, was expressed for the sort of neuro- and behavioral changes in the fetus and the infant.
BETTY ANN BOWSER: Gray thinks, when it comes to BPA, people have nothing to worry about.
EARL GRAY: I don't know that the science gives me great cause for concern about these products with Bisphenol A.
BETTY ANN BOWSER: And, Gray thinks, people don't need to eliminate all products they believe contain BPA from their lives.
The National Toxicology Program's Bucher and his staff had the Herculean job of reviewing all the studies, both pro and con, and coming up with recommendations for federal agencies about what to do.
JOHN BUCHER: There is a very large literature on Bisphenol A. It's a controversial literature. There's some conflicting studies.
And I think that we've -- in our report, we've begun to illuminate some of those conflicts and try to sort through some of those issues. We don't see much of a concern at all for exposures to adults.But the area of concern is specifically related to infants and children, especially the fetus, early infants, and early childhood exposures to Bisphenol A.
Businesses, FDA respond to pressure
BETTY ANN BOWSER: After Bucher made his announcement, Wal-Mart said it would stop selling baby bottles made with BPA by early next year. Babies 'R' Us and others already have been carrying BPA-free brands.
Even with all the attention being given to BPA, it's still hard for consumers to know what to do or even to know what products contain the chemical.
We assembled a group of plastic products -- a sippy cup, a can of tomatoes, baby food, baby bottles -- and asked neurobiologist Jennifer Sass how to tell which ones contain BPA.
JENNIFER SASS, Senior Scientist, Natural Resources Defense Council: Some do, and some don't. And the problem is the consumer doesn't have a reliable way of knowing the difference.
BETTY ANN BOWSER: Sass, who works with environmental advocacy group, says if a plastic product is clear and hard it is most likely to contain BPA. And unless the federal government were to require labeling, consumers can only make an educated guess.
JENNIFER SASS: And what they're going to need to do, unfortunately, is phone up the companies that they're interested in or phone up the Food and Drug Administration and have the governments provide information, but preferably moving away from plastics is the best choice, if you can.BETTY ANN BOWSER: Although the Food and Drug Administration insists BPA is safe, it has just formed an agency-wide task force to review the new concerns that have been raised.