Results from a US study suggest that urinary levels of the chemical bisphenol A (BPA) are positively associated with wheeze and asthma risk in young children.
Kathleen Donohue (Columbia University School of Physicians and Surgeons, New York) and team found that urinary BPA concentrations at ages 3, 5, and 7 years were positively associated with asthma risk at ages 5-12 years.
Furthermore, urinary BPA concentrations at 3 years of age were positively associated with wheeze at ages 5 and 6 years, and BPA concentrations at 7 years of age were associated with wheeze at the same age.
"Although the strength of the associations is modest, this is the first cohort study to report an association between childhood urinary BPA concentrations and asthma in children," comment the researchers in the Journal of Allergy and Clinical Immunology.
The team assessed urinary BPA concentrations in 568 women during the third trimester of pregnancy, and in their children at the ages 3, 5, and 7 years.
In the children, wheeze over the previous 12 months was assessed using parental questionnaires at ages 5, 6, and 7 years, and physician-diagnosed asthma was assessed between the ages of 5 and 12 years.
After accounting for factors such as maternal asthma, environmental tobacco smoke exposure, gender, and race/ethnicity, the team found that each log-transformed unit increase in urinary BPA concentration at ages 3, 5, and 7 years was associated with a respective 1.5-, 1.4-, and 1.5-fold increased risk for asthma at 5-12 years of age.
Furthermore, each log-transformed unit increase in urinary BPA concentration at 3 years of age was associated with a 1.4-fold increased risk for wheeze at both 5 and 6 years of age. Urinary BPA concentration at 5 years of age was not associated with wheeze at ages 5, 6, or 7 years, but BPA concentration at age 7 years was associated with a 1.4-fold increased risk for wheeze at the same age.
Surprisingly, however, maternal prenatal urinary BPA concentrations were inversely associated with infant wheeze at 5 years of age, at an odds ratio of 0.7 for each log-transformed unit increase in concentrations. There was no association between prenatal urinary BPA concentrations and wheeze in children at ages 6 or 7 years or with asthma at 5-12 years of age.
Donohue et al conclude: "These findings add to the evidence that environmental exposure to BPA might be associated with adverse respiratory outcomes."
They add, however, that "the mechanism by which BPA exposure during early childhood might influence asthma risk in subsequent years remains an open question."
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