Researchers at the University of Maryland School of Medicine in Baltimore report today that exposure to a common chemical in plastics during prenatal development is sometimes associated with pulmonary system problems later on in childhood, including reduced lung function and chronic wheezing.

Over the past three decades, health officials have observed a rise in asthma rates, and environmental factors such as airborne particles and tobacco smoke have been identified as risk factors. Some research also suggests a link between exposure to bisphenol A (BPA) and asthma.

In a study described in a report published on Monday in the journal JAMA Pediatrics, researchers looked at nearly 400 mothers and their respective infants enrolled in a birth cohort study conducted in the greater Cincinnati, Ohio, area, collecting urine samples during pregnancy and child urine samples each year after birth to measure BPA exposure. The outcomes measured were parent-reported wheeze and child forced expiratory volume in the first second of expiration, or FEV1, a standard lung function test.

The study revealed that a 14.2 percent decrease in the percentage predicted FEV1 at four years of age was associated with every 10-fold increase in average maternal urinary BPA concentration. However, the researchers found no association with the same measurements at five years of age. Every 10-fold increase in maternal urinary BPA concentration was weakly associated with about a 55 percent increase in the odds of child wheezing. A 10-fold increase in maternal urinary BPA was associated with a 4.27-fold increase in the odds of child persistent wheeze. However, no associations were observed between the outcomes and child urinary BPA concentrations.

“We found that prenatal BPA exposure that occurred during early pregnancy was inconsistently associated with diminished lung function, increased odds of wheeze and a persistent wheeze phenotype in young children,” the authors wrote. “If future studies confirm that prenatal BPA exposure may be a risk factor for impaired respiratory heath, it may offer another avenue to prevent the development of asthma.”