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Scientists Debate Bill to Restrict Chemicals

Lawmaker seeks to ban compounds in plastic baby products that may pose health risks.

January 11, 2006|Marla Cone | Times Staff Writer

Scientists on Tuesday debated the health risks of two chemicals found in plastic baby products as California legislators consider a bill that would make the state the only place in the world to restrict one of the compounds, which has been shown in some studies to mimic female hormones and possibly interfere with boys' reproductive development.

The bill, by Assemblywoman Wilma Chan (D-Alameda), would prohibit baby toys and feeding products from containing phthalates, used in the manufacture of vinyl, and bisphenol A, used in hard, clear polycarbonate plastic for an array of consumer products, including baby bottles.

No other legislative or regulatory body has restricted use of bisphenol A, which is considered an essential ingredient of polycarbonate, a light-weight and shatter-free alternative to glass.

The bill, AB 319, has sparked an intense scientific debate, as well as heavy lobbying by the plastics industry and environmentalists. If the Assembly doesn't approve the bill by the end of the month, the legislation will expire because it was introduced two years ago.

Six scientists, including two sponsored by the plastics industry, testified Tuesday at a joint hearing of two Assembly committees overseeing health and environment issues. The purpose of the hearing was for legislators and the public to hear the evidence about the health risks of the compounds that would be banned under the bill.

Evidence has been mounting that phthalates and bisphenol A could be altering the hormones and harming the reproductive systems of babies, but the results are not considered conclusive, and some studies have been controversial. While the compounds have been shown in hundreds of laboratory studies to mimic estrogen or block testosterone and feminize animals, the effects on humans are largely unknown.

Environmental health activists and some scientists say California should take a better-safe-than-sorry approach, banning the compounds in teething toys, bath toys, baby bottles and other children's products because safer alternatives are available.

But industry scientists and other representatives say California legislators would be acting with little evidence and would unnecessarily limit consumers' access to popular products.

"Human exposure is extraordinarily low," said Steve Hentges of the polycarbonate division of the American Plastics Council. "And there is no evidence that any human has been harmed by use of these products."

At the hearing on Tuesday, Fred vom Saal, a reproductive biologist at the University of Missouri-Columbia, said the effects of low doses of bisphenol A, known as BPA, are clear in animal studies.

"Every aspect of maleness is disrupted," Vom Saal said, including the animals' sperm counts, prostate size and behavior, because it blocks testosterone production.

He added that "high exposure of children is occurring and children are more sensitive than adults."

But Lorenz Rhomberg, a former Harvard and Environmental Protection Agency scientist who is now a consultant paid by the American Plastics Council, told the legislators that most studies of bisphenol A have found no effects. He served on a panel of the Harvard Center for Risks Analysis, funded by the plastics industry, which concluded in 2004 that the "evidence is very weak" that the chemical mimics estrogen.

"If you go study by study ... you see that in almost every case when there is a study that found an effect, there are four or more examples of studies that looked at the same end points and doses and found no effects," he said.

But Vom Saal countered that 140 animal studies have found hormone-altering effects from low exposure to the plastics chemical. In a published review of the studies, Vom Saal reported that every one funded by industry showed no effects while more than 90% of the government-funded studies found effects.

Regarding phthalates, Earl Gray, an EPA scientist who specializes in hormone-disrupting chemicals, said there is no debate in the scientific community that phthalates block male hormones, causing feminization of reproductive tracts in laboratory animals. Thirty to 40 studies on lab animals show the same thing, he said.

Instead, Gray said, the debate is whether the doses that people are exposed to can cause the hormonal and genetic damage seen in animals.

Industry scientists agree, saying that the animal studies are conducted with much higher doses of phthalates than people are actually exposed to.

Several human studies have linked phthalates with changes in sperm, genitals and hormone production, including one that found baby boys are born with slight changes of their genitalia.

Dr. Shanna Swan, a scientist at the University of Rochester School of Medicine and Dentistry who conducted the study of baby boys, said at the hearing that phthalate exposure is "widespread, silent and involuntary" and that safer alternatives should be used in children's toys and other products.

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