PFAS are everywhere—even when they’re not. A recent study published in Proceedings of the National Academy of Sciences is garnering significant media attention for suggesting that a crisis exists because of “wastewater-derived PFAS” potentially contaminating the drinking water of 23 million Americans. There’s only one problem—the study and its associated media coverage are treating the term “PFAS” as a four-letter word to spur interest in the findings.
Although the researchers did, technically, study a type of “PFAS,” the wastewater-containing substances that are driving their estimates are not those that are the subject of the government’s increased scrutiny. As currently defined by various organizations and government agencies, the acronym PFAS encompasses thousands of different fluorinated substances with various carbon chain lengths, side groups, and functional groups. Some define “PFAS” as any chemical containing at least one fully fluorinated carbon atom, while others require multiple fluorinated carbon atoms and/or the absence of other attached atoms besides hydrogen, such as chlorine, bromine, and iodine. There are over 10,000 substances that meet the aforementioned definitions of “PFAS,” yet relatively few have been studied with any level of scientific rigor. In fact, only a few PFAS are driving current regulations. As they relate to drinking water, there are only six that are currently regulated in the United States: are PFOA, PFOS, PFHxS, PFNA, PFBS, and HFPO-DA.
So what did the researchers study? Their stated objective was “to better understand the magnitude and composition of aqueous organofluorine discharged from large US [publicly owned treatment works] (defined as those serving >10,000 individuals) and impacts on downstream water quality.” Because they are fluorinated substances, organofluorine compounds can fall within the extremely broad definition of PFAS. But not all PFAS are created equal.
Some, like pharmaceuticals, contain the carbon-fluorine bond specifically because that bond helps to provide metabolic stability, reduces side effects, and enhances efficacy. In short, some organofluorine compounds can actually help heal ailments, not create them. It is this type of organofluorine—not those the EPA currently regulates in drinking water—that the researchers found to be most prevalent in their wastewater study. Specifically, most of the extractable organofluorine (EOF) found in the influent and effluent at POTWs, 75% and 62%, respectively, consisted of 12 fluorinated pharmaceuticals/metabolites, namely mono- and polyfluorinated pharmaceuticals. Some of those pharmaceuticals included such well-known medications as Atorvastatin (Lipitor), Citalopram (Celexa), Celecoxib (Celebrex), and Sitagliptin (Januvia).
Importantly, though, there is nothing in the study to suggest that any of those fluorinated pharmaceuticals pose a health risk to the 23 million Americans who the authors estimate will be impacted by alleged organofluorine-contaminated drinking water. Nor do the researchers contend that such fluorinated pharmaceuticals should be regulated like PFOA, PFOS, PFHxS, PFNA, PFBS, and HFPO-DA. Interestingly, as relates to the six PFAS that the EPA does regulate, the researchers found that those PFAS made up only approximately 7%-8% of the EOF content in the wastewater at the POTW—a stark difference from the 62%-75% of fluorinated pharmaceuticals that are driving the headlines. But focusing only on these fluorinated pharmaceuticals doesn’t sell. “PFAS” does.
It is time we moved beyond the headlines, focusing on what each specific fluorochemistry is, rather than on how all fluorochemistries are defined.
