March 30, 2022

BPA Exposure in The Womb May Increase Risk For Asthma, Wheezing in Girls

In utero exposure to bisphenol A appeared associated with greater odds of asthma and wheeze among school-age girls, according to a study published in Environment International.

However, exposure to bisphenol A (BPA) did not appear associated with overall lung function, nor did it appear to impact asthma and wheeze in boys.

“Bisphenols are produced in large quantities worldwide and are present in many daily life products. Thus, there is widespread exposure to them,” Alicia Abellán, PhD, postdoctoral researcher at Barcelona Institute for Global Health, told Healio.

“Of concern, these chemicals can cross the placenta and may alter critical developing processes in the fetus,” Abellán continued. “Recently, the European Food Safety Authority named bisphenol A ‘a substance of very high concern.’”

BPA is an endocrine disruptor found in the plastics and resins of many consumer products. Diet is the primary source of exposure. In addition to crossing the placenta, it also is found in breastmilk, exposing fetuses and newborns to its effects.

The researchers examined 3,008 mother-child pairs recruited between 1999 and 2010 from eight population-based birth cohorts in Europe. Concentrations of BPA as well as BPA substitutes bisphenol F (BPF) and bisphenol S (BPS) were measured in these pairs via maternal urine samples.

Detected in 90% of the samples, median concentrations of BPA ranged from 1.56 µg/g to 9.54 µg/g. Researchers detected BPF in 27% of the samples and BPS in 49%.

Overall, in utero BPA exposure tended to be associated with greater odds of school-age wheeze (OR per doubling of BPA concentration = 1.05; 95% CI, 0.97-1.13) but not with current asthma or wheezing patterns.

When stratified by sex, each doubling in BPA concentration during pregnancy was associated with higher odds of current asthma (OR = 1.13; 95% CI, 1.01-1.27) and wheeze (OR = 1.14; 95% CI, 1.01-1.3) among girls. No sex differences were observed in wheezing patterns.

Also, in utero BPS levels above the limit of detection (LOD) appeared associated with lower odds of late (OR = 0.43; 95% CI, 0.19-1) and persistent wheeze (OR = 0.56; 95% CI, 0.35-0.9).

The researchers found that increasing BPA concentrations did not appear to have significant associations with lung function parameters. For instance, each doubling in BPA concentrations was associated with a 0.02 (95% CI, 0-0.04) higher z score in FEV1 but no associations with forced vital capacity (FVC) and FEV1/FVC.

Higher FEV1 was associated with BPA exposure among boys (z score, 0.03; 95% CI, 0-0.06). Also, the researchers associated BPF levels above the LOD during gestation with higher FEV1 (z score, 0.12; 95% CI, 0.01-0.23) and mid-expiratory flow (z score , 0.13; 95% CI, 0.01-0.25).

The child’s sex was a modifier of the associations between BPF and FVC and FEV1, the researchers wrote, observing associations with higher FVC (z score, 0.17; 95% CI, 0.02-0.32) and FEV1 (z score, 0.15; 95% CI, 0-0.29) among girls.

“Sexually dimorphic effects have been previously reported in the associations of exposure to endocrine disruptors, such as BPA, with health outcomes such as asthma or obesity,” Abellán said.

“Given the endocrine-disrupting capacity of bisphenols, they can alter key hormone-signaling pathways and thus induce changes in sex hormones, which may partly explain the results found in our study,” Abellán continued. “Of importance, fluctuations of sex hormones and their consequences on immune functions can play a role in asthma pathogenesis.”

Abellán and colleagues called for further research into how temporal variabilities in exposure are assessed in relation to health outcomes so current legislation in the European Union regarding chemicals could be improved.

“In our study, the detection of BPA substitutes like BPF and BPS was lower than BPA. However, our study reflects the exposure levels from the early 2000s, when these substitutes were not as present in the market as they are currently,” Abellán said.

“We expect the current population’s exposure to be higher, which guarantees the need for further investigation,” Abellán continued. “We hope our study is useful for policymakers by providing more evidence that may help develop the appropriate public health policies.”