Swedish researchers have found that babies born to women living near a polluted municipal water supply have a higher likelihood of developing asthma due to the presence of Perfluoroalkyl substances (PFAS) in utero. The study combined data from public records for drinking water exposure and asthma rates in a study conducted by researchers in Blekinge County, which had been contaminated with PFAS for decades. The researchers found that childhood asthma was more likely in cases where the baby was exposed to "very high" PFAS levels. The US Geological Survey estimates that at least 45% of tap water in the country is contaminated withPFAS. The authors of the study are calling for more PFAS studies globally, especially to better understand the compounding variables contributing to asthma.