A controversial, estrogen-like chemical in plastic could be harming the development of children's brains and reproductive organs, a federal health agency concluded in a report released Tuesday.

The National Toxicology Program, part of the National Institutes of Health, concluded that there was "some concern" that fetuses, babies and children were in danger because bisphenol A, or BPA, harmed animals at low levels found in nearly all human bodies.

An ingredient of polycarbonate plastic, BPA is one of the most widely used synthetic chemicals in industry today. It can seep from hard plastic beverage containers such as baby bottles, as well as from liners in cans containing food and infant formula.

The federal institute is the first government agency in the U.S. to conclude that low levels of BPA could be harming humans. Its findings will be used to help regulators at federal and state environmental agencies to develop policies governing its use.

The draft report followed an 18-month review that was fraught with allegations of bias, heated disputes among scientists and the firing of a consulting company with financial ties to the chemical industry.

Some scientists suspect that exposure early in life disrupts hormones and alters genes, programming a fetus or child for breast or prostate cancer, premature female puberty, attention deficit disorders and other reproductive or neurological disorders.

In its new report, the National Toxicology Program, which reviewed about 500 laboratory animal experiments, concluded that there was "some concern" that fetuses, babies and children were at risk from BPA. It rated as "negligible" the concern for adults.

When animal fetuses or newborns are exposed, BPA "can cause changes in behavior and the brain, prostate gland, mammary gland and the age at which females attain puberty," the agency's draft report says.

"These studies only provide limited evidence for adverse effects on development and more research is needed to better understand their implications for human health," it said. "However, because these effects in animals occur at bisphenol A exposure levels similar to those experienced by humans, the possibility that bisphenol A may alter human development cannot be dismissed."

Plastics industry representatives stressed that the agency found "no serious or high-level concerns." They call the lab animal experiments inconclusive and flawed.

Steven G. Hentges of the American Chemistry Council's polycarbonate/BPA group said the findings "provide reassurance that consumers can continue to use products made from bisphenol A."

"The limited evidence for effects in laboratory animals at low doses primarily highlights opportunities for additional research to better understand whether these findings are of any significance to human health," he said.

In the key area of reproductive health, the agency reported more concern about the potential dangers to children than its advisory panel did.

The advisory panel in August found "minimal" concern about effects on the prostate and puberty after siding with the plastics industry and disqualifying many animal studies that showed effects. That drew criticism from scientists who conducted the research.

But in the new report, the National Toxicology Program overruled its panel, elevating its finding about human prostates and puberty to "some concern." It also for the first time expressed concern about effects on human mammary glands, which the panel had not addressed.

The findings "break new scientific ground" by validating the low-dose animal tests, said Anila Jacob, senior scientist at Environmental Working Group, an activist group. It "reflects a significant body of science showing that BPA may play a larger role than previously thought in a host of common health problems, including prostate cancer, breast cancer and early puberty," she said.

Frederick vom Saal, a reproductive scientist at University of Missouri-Columbia who studies BPA, said the new report was "very, very much in line" with a consensus statement signed by 38 scientists last year that said the chemical could be harming babies' brains and reproductive tracts.

"This is going to ripple around the world," vom Saal said. "The bottom line is there really is a convergence of opinion that is occurring."

Canada is expected soon to declare BPA a toxic substance, which would be followed by proposals to control its use. California and other states have considered but not adopted bans on BPA in products.

A year ago, the Los Angeles Times reported that the government was basing its BPA decision on a summary of the science drafted by a private company, Sciences International, which had financial ties to more than 50 chemical companies and groups. The company was then fired. National Toxicology Program officials audited the report and found it unbiased, so it was used to reach its conclusions.

The National Toxicology Program will accept public comments on its draft report until May 23, and it will be reviewed by a new scientific panel in June.

marla.cone@latimes.com

© 2008 The Los Angeles Times