Children who were exposed to extremely high levels of per- and polyfluoroalkyl substances (PFAS) before birth had a significantly higher likelihood of developing asthma, according to research published in PLOS Medicine on Apr. 14.
This study is important because it offers rare real-world evidence from a community with unusually high PFAS contamination, raising questions about the risks associated with early-life exposure to these so-called "forever chemicals." Asthma remains the largest contributor to non-infectious illness among children, and its prevalence has been rising over the past five decades.
Researchers examined data from 11,488 children born in Blekinge County, Sweden. About one-third of households in Ronneby—a town within the county—were exposed for over 30 years to drinking water contaminated by PFAS from aqueous film-forming foam. The concentration of PFAS in polluted water reached as high as 10,380 ng/L compared with much lower levels elsewhere. The study used water distribution records and maternal serum samples to estimate prenatal exposure categories ranging from background up to very high.
The findings showed that children with very high prenatal PFAS exposure had a 44 percent higher hazard of developing asthma compared with those in background exposure groups. In absolute terms, nearly 27 percent of highly exposed children developed asthma versus just over 16 percent among those less exposed. The association was not observed at lower exposure levels or for wheezing outcomes alone.
Researchers noted that lung development can be disrupted by environmental pollutants like PFAS, which may concentrate in lung tissue and alter immune responses or gene expression profiles related to respiratory health. Previous studies have produced mixed results regarding PFAS and childhood asthma risk; however, this research suggests that only exceptionally high exposures are linked with increased risk.
While the study benefitted from detailed clinical follow-up data and covered a wide range of exposures—including an atypically highly-exposed group—the authors acknowledged limitations such as potential misclassification due to using residential addresses instead of direct biomarker measurements for prenatal exposure. They also cautioned that many affected children continued living in contaminated areas after birth, making it difficult to separate prenatal effects from ongoing early-life exposures.
The authors concluded that further studies using direct measurement methods are needed before confirming these results or applying them more broadly.
