Researchers analyzed the breast milk of 50 first-time mothers in the Seattle area, searching for the presence of 39 per- and polyfluoroalkyl substances (PFAS), and detected the compounds in every sample (Env. Sci. Technol. 2021, DOI: 10.1021/acs.est.0c06978). The study marks the first report of PFAS levels in breast milk in the US in 15 years and measures more of the substances with lower detection limits than previous work, the authors say. PFAS are part of nonstick coatings, food packaging, and firefighting foam. Some have been implicated in health problems including suppressed immune function and some types of cancers. The “legacy” PFAS perfluorooctanesulfonic acid and perfluorooctanoic acid have been phased out because of health concerns, including accumulation in the body, and replaced in many applications by shorter-chain versions, such as perfluorohexanoic acid (shown). “The idea before was that new PFAS don’t accumulate” because of their smaller size, study author and environmental chemist Amina Salamova of Indiana University says. But the new study detected legacy and new PFAS at comparable levels in the breast milk samples. “We now have evidence, based on this study, that some of the current-use PFAS can also accumulate in breast milk, similar to legacy PFAS,” she says. The researchers don’t know what effects this PFAS exposure could have on infants, but effects are possible “because we know that everyday levels in adults can lead to health effects,” particularly on immune function, Salamova says.