A nationwide collaboration of scientists led by a University of Missouri-Columbia researcher is strengthening warnings about a ubiquitous chemical that could be harming humans.

Vom Saal

Frederick vom Saal, MU professor of reproductive biology and neurobiology, has spent years studying bisphenol-A and its effects on laboratory animals. Bisphenol-A is an extremely popular chemical that companies use to make clear plastic containers for food and water, including baby bottles. Vom Saal and dozens of colleagues this week issued a stern warning that humans might be at risk, especially the very young.

"There really is at this point sufficient information to warrant concern about exposure to this chemical, particularly for our fetuses and babies," vom Saal said. "The public needs to be aware of that."

Although valuable for making attractive plastic containers, bisphenol-A is also a potent sex hormone that is very similar to estrogen. Research has shown that bisphenol-A leaches from food containers in small doses that increase over time and after the container has been heated.

Scientists have tested very small doses of bisphenol-A on laboratory mice and rats and found it produces a list of ailments: prostate and breast cancer, urogenital abnormalities in male babies, reduced sperm quality, early puberty in girls, insulin-resistant diabetes, obesity and neurobehavioral problems such as attention deficit hyperactivity disorder.

In addition, a new study showed bisphenol-A given to mice when they are very young causes reproductive problems that emerge when they become adults.

"We found an increase in abnormalities in the ovaries and in the reproductive tract, as compared to the control animals," said Retha Newbold of the division of intramural research at the National Institute of Environmental Health Sciences in North Carolina. "Some of these things we found were cystic ovaries and paraovarian cysts. These cysts are located just outside of the ovary and have been associated with fertility problems both in mice and in humans."

Vom Saal and the other researchers aren’t surprised that the list of abnormalities resembles, in many ways, the diseases and disorders that seem to be increasing in humans. Compared to the levels of bisphenol-A given to animal subjects, scientists have found even higher levels "in the blood of virtually all people in the United States and in other developed countries," vom Saal said.

The research into the effects of bisphenol-A began in labs at MU. But now many scientists are examining the chemical. To date, more than 700 papers have been published on the topic.

The research has remained controversial, however, with industry groups contending that bisphenol-A is safe.

Recently, a panel of prominent researchers, including vom Saal and Newbold, reviewed all the scientific findings, weighed the evidence and came to the consensus that concerns about the chemical are warranted. They released a consensus statement yesterday in the journal Reproductive Toxicology, signed by 38 researchers and written by vom Saal, to inform their colleagues and citizens that the debate should be considered over. "This is the most comprehensive set of data regarding an environmental chemical of concern ever assembled," said Jerrold Heindel,with the division of extramural research and training at the National Institute of Environmental Health Sciences.

But Steven Hentges, of the American Chemistry Council’s Polycarbonate/BPA Global Group, suggested that the scientists are biased, noting that several have spoken out against bisphenol-A in the past. He said the industry is putting its stock in an upcoming evaluation by the National Toxicology Program’s Center for the Evaluation of Risks to Human Reproduction.

"With the scientifically sound CERHR evaluation of bisphenol-A so near to completion, we’re dismayed to see a competing and far less sound evaluation released and publicized this week, apparently in an attempt to upstage CERHR," Hentges said in a news release.

The Center for the Evaluation of Risks to Human Reproduction has been accused of having ties to the chemical industry through a group hired to write a bisphenol-A report. A recent government audit found no problems, however.

The current body of research lacks studies actually conducted with human subjects. But vom Saal said there are reasons to believe people are having similar reactions as the animal subjects.

"At the cellular level, there is essentially no difference in the way that mouse cells or rat cells respond to bisphenol-A and human cells respond to it," vom Saal said, "so the concern is that these mouse and rat studies are really quite relevant to humans."

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