First, EPA published its human health toxicity assessment for “GenX chemicals,” also known as hexafluoropropylene oxide (“HFPO”) dimer acid (and don’t forget its ammonium salt!). EPA has pegged HFPO’s toxicity at 7-100 times higher than that of other PFAS compounds for which assessments already exist, such as PFBS, PFOA, and PFOS. It’s probably worth noting that GenX was developed to replace PFOA. Because it’s a shorter chain molecule, the expectation was that GenX would pose less environmental risk.
The second development this week was that EPA announced it was commencing a rulemaking to propose adding all of the compounds mentioned above as hazardous constituents in what is known as “Appendix VIII” to the hazardous waste regulations at 40 CFR Part 261. Adding the PFAS compounds to Appendix VIII subjects them to potential corrective action requirements. It’s also safe to say that the listing in Appendix VIII is simply the first step towards listing them as hazardous wastes under RCRA and hazardous substances under CERCLA.
It’s going to be some time before we really have our arms around the total tab for addressing PFAS contamination, but it’s definitely not going to be a small number.