text: Fluorosurfactants such as PFOS, PFOA, and PFNA have caught the attention of regulatory agencies because of their persistence, toxicity, and widespread occurrence in the blood of general populations and wildlife. In 2009, PFOS, its salts, and perfluorooctanesulfonyl fluoride were listed as persistent organic pollutants under the Stockholm Convention due to their ubiquitous, persistent, bioaccumulative, and toxic nature. PFAS chemicals were dubbed "forever chemicals" in a 2018 op-ed in the Washington Post. The nickname was derived by combining the two dominant attributes of this class of chemicals: PFAS chemicals are characterized by a carbon-fluorine backbone (the "F-C" in "forever chemicals"), and the carbon-fluorine bond is one of the strongest bonds in organic chemistry, which gives these chemicals an extremely long environmental half-life. The term forever chemicals is commonly used in media outlets in addition to the more technical name of per- and polyfluorinated alkyl substances. Their production has been regulated or phased out by manufacturers, such as 3M, DuPont, Daikin, and Miteni in the U.S., Japan, and Europe. In 2006 3M replaced PFOS and PFOA with short-chain PFASs, such as perfluorohexanoic acid (PFHxA) and perfluorobutanesulfonic acid (PFBS). Shorter fluorosurfactants may be less prone to accumulating in mammals; there is still some concern that they may be harmful to both humans and the environment, though the EPA states, "...research is still ongoing to determine how different levels of exposure to different PFAS can lead to a variety of health effects." Many PFASs are either not covered by European legislation or are excluded from registration obligations under the EU REACH chemical regulation. Several PFASs have been detected in drinking water, municipal wastewater, and landfill leachates worldwide.
  It had been thought that PFAAs would eventually end up in the oceans, where they would be diluted over decades, but a field study published in 2021 by researchers at Stockholm University found that they are significantly transferred from water to air when waves break on land, and are a significant source of air pollution, and eventually get into the rain. The researchers concluded that pollution "may impact large areas of inland Europe and other continents, in addition to coastal areas".