Children exposed to the chemical bisphenol A (BPA) had an elevated risk for asthma in study published in the Journal of Allergy and Clinical Immunology (March 2013, Vol. 131:3, pp. 736-742).
The report, by researchers at the Columbia Center for Children's Environmental Health at the Mailman School of Public Health in New York, is the first to find an association between early childhood exposure to BPA and asthma, the researchers noted in a press release.
Animal studies have associated BPA -- which is used in some dental sealants -- with breast and prostate cancers, as well as reproductive and behavioral abnormalities. In addition, some research has tied BPA to cardiovascular disease, miscarriage, decreased semen quality, and childhood behavioral issues. The chemical also may affect metabolism, diabetes, and obesity, although more studies are required to determine its effects.
The study followed 568 women enrolled in the mothers and newborns study of environmental exposures. BPA exposure was determined by measuring levels of a BPA metabolite in urine samples taken during the third trimester of pregnancy and in the children at ages 3, 5, and 7.
Physicians diagnosed asthma at ages 5 to 12 based on asthma symptoms, a pulmonary function test, and medical history. A questionnaire was used to evaluate wheeze.
After adjusting for secondhand smoke and other factors known to be associated with asthma, the researchers found that postnatal exposure to BPA was associated with increased risk of wheeze and asthma.
BPA exposure during the third trimester of pregnancy was inversely associated with risk of wheeze at age 5, the researchers found. This unexpected finding is in contrast to the results of a previous study, which found that BPA exposure during the second trimester, a critical period for the development of airways and the immune system, was positively linked with risk for asthma.
In three periods, more than 90% of the children in the study had detectable levels of BPA metabolite in their bodies, a finding that is in line with previous research.
But the findings do not mean all children exposed to BPA will develop asthma, the researchers noted.
The biological mechanism behind the BPA-asthma connection is unclear. The current study found no evidence that exposure to BPA increased the risk that the immune system would develop more antibodies to common airborne allergens.
The report builds on existing evidence linking BPA exposure to respiratory symptoms, among a range of health problems. In July, the U.S. Food and Drug Administration banned BPA in baby bottles and sippy cups.
