Published: May 6, 2013 | Updated: May 6, 2013

By Joyce Frieden , News Editor, MedPage Today

Action Points

• This study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
• BPA exposure was associated with a modest decrease in two lung function parameters in children – one associated with small airway function and the other associated with pulmonary obstruction.

WASHINGTON — Increased levels of the chemical bisphenol A, found in some plastic products and can linings, were associated with decreases in two markers of pediatric lung function, researchers reported here.

Among 661 children ages 6 to 19, each log-unit increase in bisphenol A (BPA) was associated with a 4% decrease in forced expiratory flow between 25% and 75% of vital capacity (FEF[25-75]) — a measure of small airway function — and a 1% decrease in the ratio of forced expiratory volume (FEV1) to forced vital capacity (FVC), Adam Spanier, MD, of Pennsylvania State University College of Medicine in Hershey, Pa., and colleagues found.

The results “suggest a possible mechanism for the BPA effect we’ve seen in epidemiologic studies — obstruction of small airways — which does merit additional evaluation in future prospective studies,” Spanier said at the annual meeting of the Pediatric Academic Societies.

BPA is found in many consumer products, and about 90% of the U.S. population has been exposed to it, Spanier noted. Exposure to BPA can be measured in the urine.

One animal study showed that perinatal BPA exposure promotes an allergic model of asthma in mice, and work done by Spanier and colleagues has shown that prenatal BPA concentration is associated with wheezing in children (Environ Health Perspect. June 2012; 120(6): 916–920). A more recent study showed that BPA concentrations found in children at ages 3, 5, and 7 were associated with an asthma diagnosis at ages 5 through 12, he said.

To further examine the relationship between BPA exposure and pulmonary function in children, Spanier and colleagues performed a cross-sectional analysis of 2007-2010 data from the National Health and Nutrition Examination Survey (NHANES). The NHANES includes an exam component containing medical, dental, and physiological measurements, as well as laboratory test results.

The investigators looked at urinary BPA levels as well as four pulmonary function parameters: FEV1, FEF(25-75), FVC, and FEV1/FVC. The study’s primary outcome measure was spirometry.

Slightly more than half of study participants were male; participants’ average age was 13. Nearly a quarter (24.1%) of participants were obese and 14.5% were overweight. In addition, 18.9% of respondents reported physician-diagnosed asthma, and almost 20% had suffered a respiratory illness in the previous week, Spanier noted.

Participants’ mean BPA concentration was 4.3 ng/mL, and only 15% of children had a level of exposure that was considered to be low.

When the researchers calculated the percent predicted values of the four pulmonary variables, all were close to 100%, but the range of distribution varied, Spanier said.

Multivariable analysis adjusting for urinary creatinine, asthma diagnosis, recent cold, body mass index, age, poverty-income ratio, gender, race, and serum cotinine showed that although increases in BPA were associated with decreases in FEF(25-75) and the FEV1/FVC ratio — P=0.01 and P=0.02, respectively — they were not associated with FEV1 or FVC alone, the researchers found.

Also, dividing participants into quartiles based on their BPA levels and comparing those in the top quartile to those on the bottom, participants in the highest quartile had an average FEF(25-75) that was 10% lower than those in the lowest quartile, and an FEV1/FVC ratio that was 3% lower, Spanier said.

Limitations included missing data, the short half-life of BPA, and the fact that it was a cross-sectional study, so that the researchers could not suggest causality.