EPA has released its risk assessment for GenX, one of the hundreds of "forever chemicals" known collectively as PFAS that are ubiquitous in our environment owing to decades of use in everything from fire suppressants to pizza boxes. Experts have concluded that if the same principles were used to assess the risk associated with other PFAS that were used to finally assess the risk associated with GenX, the predicted safe levels of those other PFAS would be much lower.
In the risk assessment, EPA more than halved what it considers a safe "dose" of GenX. EPA did that under pressure from certain States to increase the effect on its risk assessment of what are known as "uncertainty factors". To over simplify things, "uncertainty factors" magnify calculated risk to account for what one doesn't know about the toxicity of a chemical. Ultimately those "uncertainty factors" may prove to have been far too conservative but, if past is prologue, by the time that is known, no one will be listening.
EPA finds itself in a bit of a jam. The more it suggests that the risks associated with PFAS may be greater than it previously calculated, the more it faces increased pressure to immediately eliminate those risks. And, as we know from the PFAS Roadmap released last month, it is going to take at least several months to begin to make the changes to federal regulations necessary to do that under federal law. On the other hand, if EPA doesn't appear to be keeping up with the States that have already set and are setting much lower "safe" limits for PFAS, EPA might be criticized for not doing its job.
For now the States that have already regulated PFAS will continue to drive behavior in the regulated community and panic over PFAS will likely continue to increase.
In its response to comments document for the GenX assessment, EPA signaled that such studies were not the decisive factor in its decision to tighten its final RfD to 3×10^-6 milligrams per kilogram bodyweight per day (mg/kg-day) -- an order of magnitude stricter than the proposed value of 8×10^-6 mg/kg-day. This is likely because there is far less information available about the newer GenX than PFOA and PFOS. Specifically, the agency wrote, the key was its decision to increase the assessment’s uncertainty factors -- multipliers of up to 10 that regulatory agencies use to increase the conservativism of RfDs to account for various types of uncertainty . . . EPA notes in its response to comments that Pennsylvania and Minnesota regulatory agencies and other environmental groups urged EPA to increase its database uncertainty factor (UFD) from 3 to 10
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