Megan Brooks

April 01, 2011

April 1, 2011 (San Francisco, California) — Exposure during childhood to the widely used industrial chemical bisphenol-A (BPA) may increase the risk for asthma, according to a study presented here at the 2011 Annual Meeting of the American Academy of Allergy, Asthma & Immunology.

"This is the first report of an association between BPA and asthma in humans," study presenter Kathleen M. Donohue, MD, from Columbia Presbyterian Medical Center in New York City, noted in an interview with Medscape Medical News.

BPA has been used for decades to make hard plastic containers, including cups and baby bottles, and in the lining of metal food and beverage cans.

"Some animal studies have shown that BPA can influence Th2 pathways and T regulatory cell pathways, which are important in asthma pathogenesis," Dr. Donohue said. "Therefore, we hypothesized that exposure to BPA might be associated with increased odds of wheeze and asthma."

Columbia Center for Children's Environmental Health Birth Cohort Study

To investigate, Dr. Donohue and colleagues turned to the Columbia Center for Children's Environmental Health study, an ongoing prospective birth cohort study that has recruited 400 women and their children to date.

Total urinary BPA level was analyzed via mass spectrometry when the children were 3, 5, and 7 years old. Child wheeze in the past 12 months was assessed using the International Study of Asthma and Allergies in Childhood questionnaire. Allergists conducted standardized exams and pulmonary function tests to determine current asthma status using prespecified criteria. The results were controlled for a variety of factors including sex, race/ethnicity, maternal asthma, and exposure before and after birth to environmental tobacco smoke.

The cohort is 47% male, 59% Dominican, and 41% African American; 21% of the patients have a maternal history of asthma, and 35% had prenatal and 41% postnatal environmental tobacco smoke exposure.

Modest Effect Seen With BPA Exposure

"We found that the urinary BPA level in children at ages 3 and 7 years was associated with an increased odds of asthma," Dr. Donohue reported, adding: "The effect size is modest."

At age 3 years (n = 333), the odds ratio (OR) was 1.34 (95% confidence interval [95% CI], 1.02 - 1.76; P = .03). At age 7 years (n = 292), the OR was 1.38 (95% CI, 1.03 - 1.86; P = .03).

Urinary BPA level at age 3 years also was associated with increased odds of wheeze at age 7 years (OR, 1.34; 95% CI, 1.01 - 1.83; P = .04).

The mean urinary BPA level at age 3, 5, and 7 years was 7.6, 5.5, and 6.0 ng/mL, respectively. These levels are "somewhat higher" than in other published studies, Dr. Donohue noted. "This is likely because our samples were first morning voids, whereas the other studies in children used spot urine samples. First morning voids tend to be more concentrated. We controlled for urine concentration in our multivariate models."

Dr. Donohue emphasized that this study provides "interesting," but "very preliminary," data that "needs to be followed-up and replicated in other cohorts."

Rebecca G. Piltch, MD, who was not involved in the study, agreed. "It is still too early to draw conclusions one way or another," said Dr. Piltch, who has a private practice in San Francisco, California, specializing in allergy, asthma, and immunology care for infants, children, and adults.

Dr. Donohue and colleagues plan to continue their research and conduct mechanistic studies to see how BPA may affect the airways of children.

The Columbia Center for Children's Environmental Health study is supported by the National Institute of Environmental Health Sciences, part of the National Institutes of Health. The authors and Dr. Piltch have disclosed no relevant financial relationships.

2011 Annual Meeting of the American Academy of Allergy, Asthma & Immunology: Abstract 553. Presented March 20, 2011.


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