As a group of US scientists issue a warning about BPA, the contentious debate over the plastic compound intensifies, writes Marla Cone.
Scientists in the US issued a strongly worded consensus statement warning that an oestrogen-like compound in plastic is likely to be causing an array of serious reproductive disorders in people.
The compound, bisphenol A or BPA, is one of the highest- volume chemicals in the world and has found its way into the bodies of most human beings.
Used to make hard plastic, BPA can seep from beverage containers and other materials. It is used in all polycarbonate plastic baby bottles, as well as other rigid plastic items, including large water cooler containers, sports bottles and microwave oven dishes, along with canned food liners and some dental sealants for children.
The several dozen scientists - including four from US federal health agencies - reviewed about 700 studies before concluding that people are exposed to levels of the chemical exceeding those that harm lab animals. Infants and foetuses are most vulnerable, they said.
The statement, published online by the journal Reproductive Toxicology, was accompanied by a new study by researchers from the National Institutes of Health finding uterine damage in newborn animals exposed to BPA.
That damage is a possible predictor of reproductive diseases in women, including fibroids, endometriosis, cystic ovaries and cancers.
It is the first time BPA has been linked to female reproductive tract disorders, although earlier studies have found early-stage prostate and breast cancer and decreased sperm counts in animals exposed to low doses.
The scientists' statement and new study - along with five accompanying scientific reviews that summarise the 700 studies - intensify a highly contentious debate over whether the plastic compound poses a public threat. So far no governmental agency in the US or in Europe has restricted its use.
Representatives of the plastics industry lambasted the scientists as alarmist and biased, and said they based their conclusions on inconsistent and uncertain science.
"Considering many of these people have made their views known in the past, is there any surprise? Is there really anything new?" asks Steve Hentges of the American Chemistry Council's polycarbonate/BPA group.
Hentges says the scientists who signed the consensus statement are self-selected, leaving out many experts, and that many have conflicts of interest because they have either studied BPA and reported effects or "have already taken a very clear advocacy position".
"They are completely at odds with the findings of every governmental scientific body that has reviewed the same science," he says.
Two government scientific committees in Europe and Japan recently decided there is insufficient evidence to restrict the compound. Europe's food safety agency decided in January that the data was inconclusive, largely because of metabolic differences between mice and humans, and because it is uncertain the amounts people are exposed to pose a human health threat.
This week a US expert panel convenes to decide whether to declare BPA a human reproductive toxin, which could be a first step toward federal regulation.
The review by the panel of the federal Center for the Evaluation of Risks to Human Reproduction, part of the National Institutes of Health, has been controversial.
It was reported in March that its preliminary report on BPA was written by a consulting firm with financial ties to the chemical industry that has since been fired by the centre.
Frederick vom Saal, a University of Missouri at Columbia reproductive toxicologist, says the scientists' statement on BPA "is very different than any other approach to any chemical".
"We now have, without a doubt, the most comprehensive set of documents covering every aspect of bisphenol A and the hope here is that government panels will actually look at this information, digest it, and incorporate it into their decision-making," says vom Saal, who is the most vocal scientist studying BPA.
No studies have been conducted looking for effects in people, and one goal of the scientists who signed the statement is to generate human research.
Jerrold Heindel, a scientist with the National Institute of Environmental Health Sciences who organised a meeting last autumn to begin drafting the statement, says that even though there have been no human studies of BPA, there is now so much animal data that the 38 experts believe that potential human damage is likely.
More than 150 studies have found health effects in animals that have been exposed to low doses.
"We know what doses the animals were given, and when we look at humans, we see blood levels within that range or actually higher, which is a cause of concern and there should be more human research," he says.