BPA exposure may raise child's asthma risk

Asthma rates climb in the United States every year, and a new study suggests exposure to the chemical BPA may be a reason.

Asthma is disease that causes wheezing, chest tightness, coughing and other breathing difficulties. It can last a lifetime.

In 2001, one in 14 Americans -- or 20 million people -- had asthma. By 2009, the rates climbed to one in 12 people, or 25 million Americans. That means eight percent of the U.S. population is asthmatic, and more than half of them have suffered a recent asthma attack, according to the American Academy of Allergy, Asthma and Immunology.

"Asthma prevalence has increased dramatically over the past 30 years, which suggests that some as-yet-undiscovered environmental exposures may be implicated," explained study author Dr. Kathleen Donohue, an assistant professor of Medicine at Columbia University College of Physicians and Surgeons and an investigator at the Center for Children's Environmental Health, in a press release. "Our study indicates that one such exposure may be BPA."

BPA, or bisphenol A, is a ubiquitous chemical found in food packaging like cans (to prevent corrosion caused by food), plastics such as tableware and other storage containers.

The chemical has been considered hormone-disrupting, with reported links to behavioral disorders, reproductive defects, obesity risk and immune system problems. The U.S. Food and Drug Administration has banned BPA from baby bottles and sippy cups as of July 2012 because studies of young developing animals showed health concerns. But, the agency rejected an outright ban the chemical, saying the evidence at the time did not suggest that BPA exposure through our diets is unsafe.

Donohue and colleagues tracked 568 women who were enrolled in study of environmental exposures in mothers and newborns. BPA levels were measured from mom's urine samples during her third trimester and in the children at ages 3, 5 and 7-years-old.

After ruling out secondhand smoke and other causes of asthma, the researchers tied "fairly routine, low doses" of BPA exposure in children to increased risk for wheezing and asthma.

"Just as smoking increases the risk of lung cancer but not everyone who smokes gets lung cancer, not every child exposed to BPA will develop asthma," said Donahue.

At all three ages, 90 percent of kids in the study had detectable levels of BPA in their bodies, which is consistent with past research. Unexpectedly, the researchers found BPA exposure during the third trimester was inversely associated with risk for wheezing.

"Like most other scientists studying BPA, we do not see a straightforward linear dose-response relationship," she said.

The study is published in the March issue of Journal of Allergy and Clinical Immunology.

"This is the first study to identify an association of childhood BPA exposure with the development of asthma,"Dr. Leo Trasande, an associate professor of pediatrics and environmental medicine at NYU Langone Medical Center in New York City, told CBSNews.com in an email.

Trasande was not involved in the research, but has authored recent studies that linked BPA exposure to obesity ratesand presence of protein markers associated with risk for kidney damage and heart disease.

"While further research is needed to be certain that this association applies to the entire US population, it adds to ongoing concerns about this dietary contaminant, and about the decision by the FDA to await further evidence before limiting uses in aluminum cans and other food containers," he said.

Other experts were less convinced.

"I would not recommend that my patients avoid the chemical based on this article," Dr. Claudia Fernandez, a pediatric pulmonologist at Miami Children's Hospital in New York City, told HealthDay.

The industry group the American Chemistry Council also disputed the findings.

"The increasing rate of asthma among children is an important public health issue, but there is no scientific consensus on what is causing the increase and this study adds little relevant information to the debate," Steven Hentges, a representative at the American Chemistry Council, said in a prepared statement to Scientific American. "Because of the limited study design based on single samples to monitor exposure, it is difficult to draw any meaningful conclusions from this report."

The FDA says consumers who want to limit their BPA exposure should avoid plastics with recycle codes 3 or 7, which may be made with BPA. Also, putting hot or boiling liquid into plastic containers with BPA may increase exposure. Discard plastic bottles with scratches because they may contain bacteria that increases the release of BPA.

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