> About a quarter of new pharmaceuticals are PFAS Huh, TIL. I was going to rebut this but I looked into it. I didn't realize simply the presence of a -CF3 grou

> About a quarter of new pharmaceuticals are PFAS Huh, TIL. I was going to rebut this but I looked into it. I didn't realize simply the presence of a -CF3 group is enough to classify the whole molecule as a PFAS according to new definitions. > More recently (2021) the Organisation for Economic Co-operation and Development (OECD) expanded the definition, stating that "PFASs are defined as fluorinated substances that contain at least one fully fluorinated methyl or methylene carbon atom (without any H/Cl/Br/I atom attached to it), i.e. with a few noted exceptions, any chemical with at least a perfluorinated methyl group (–CF3) or a perfluorinated methylene group (–CF2–) is a PFAS."[3][4] That's a super popular moeity in medchem for whatever reason, so yeah, RIP all thing trifluoromethyl. Difluromethylene can be degraded much more quickly as long as the molecule can be "unzipped" (needs a break point where nucleophilic attack can occur), so it's possible we may be able to sub in -CHF2 or -CH2F to "cap" molecules and render them less persistent.