(Like all my blog entries, this is intended to be informative but not intended as legal advice in any specific situation; and no one should be relying on any generic regulatory interpretations herein, as a substitute for careful fact-specific evaluation of regulations and guidance) . 

Shortly after posting my April 29 blog on PFAS groundwater contamination, I learned that EPA had published revised draft guidance on risk-based action levels for both PFOA and PFOS.  Thus, a brief update is necessary.

For the last 10 years, EPA health advisory levels have ranged from 0.2 ug/l PFOS and 0.4 ug/l PFOA [ 2009], to 0.070 ug/l (“70 ppt”) for either chemical, individually or combined [ 2016].  

The April 25, 2019 guidance does NOT change EPA’s 70 ppt number.  It just clarifies that this number is the default “preliminary remediation goal” (PRG) in the absence of a federal or state drinking water standard. The new development is that they are recommending 40 ppt as a “screening level”—which means: below that level is considered acceptable risk; and above that level requires evaluation. As I interpret the guidance, this number is NOT based on new conclusions about underlying health risk of PFOA and PFOS. It is simply the mathematical result of modifying the “hazard quotient” (HQ) factor,  to reflect potential additive toxicity of PFOA and PFOS, as well as the likely existence of other PFAS compounds for which toxicity has not yet been evaluated.  70 ppt  is still the  number they stand by for purposes of defining unacceptable lifetime risk, and defining RMG.     

This interim guidance feels like an attempt to wade a little further  into this growing and important public health issue, while being very mindful of the huge potential remedial costs for over 400 federal military bases, and the substantial public drinking water utility costs as PFAS continue to be found all over the country.  It is likely that state drinking water and cleanup standards will be the primary factor for PFAS contamination situations in the foreseeable future; and those numbers are trending lower than 70 ppt and even 40 ppt.