by John Oberer, LSRP, GZA GeoEnvironmental

It’s no secret that there’s little agreement between governments about acceptable levels of PFAS. But as co-author of the white paper “Site-Specific PFAS Risk Assessment: Regulatory Variability and Implications for Management,” first published in the Journal of the New England Water Works Association in their June 2026 issue, what was surprising was the different outcomes that different regulatory frameworks provided.

Site-Specific Risk Assessments (SSRAs) are critical tools for evaluating the magnitude and nature of human and ecological risks at PFAS-contaminated sites, but they don’t have a regulatory focus. Furthermore, not all regulatory frameworks allow the use of SSRAs, instead using proscriptive comparisons to fixed standards, similar to how the USEPA uses maximum contaminant levels (MCLs) to enforce drinking water standards. The purpose of our paper was to see how SSRAs could be translated into risk management under different state and federal regulations.

We used four different frameworks for our study: USEPA guidance, and regulatory guidance or proscriptive standards from Massachusetts, Wisconsin, and New Jersey. The site we chose had a long and checkered history, having been used for railcar cleaning and refurbishing, automotive recycling, railroad tie dipping, contractor laydown areas, and metals recycling. While these industries are not specifically known for PFAS use, some contribution was likely from the automotive recycling.  In addition, there were a series of fires at this site over the decades, some of which were likely extinguished using aqueous film-forming foam (AFFF).  The site also bordered on a former uranium processing facility, where PFAS use was quite likely.

In the paper, we focused on risks associated with groundwater used for drinking water purposes, using data from four monitoring wells. Yet the same objective data yielded very different regulatory results.

Under federal guidance and using Wisconsin’s standards, PFAS concentrations at one well were beyond the levels designated as a significant health risk. In Massachusetts and New Jersey, however, the standards didn’t indicate significant risks.

Another factor was which compounds were regulated. All four regulatory regimes had standards for PFOA and PFOS, but federal standards regulated five compounds, Massachusetts six, and New Jersey four. Furthermore, as we performed our study, it was clear that more compounds would eventually be regulated. Wisconsin, meanwhile, uses a hazard index approach for mixtures of up to 12 different compounds. All of this would influence how the SSRA is performed and its recommendations. Other challenges also surfaced as we continued the study. There are over one hundred PFAS compounds that have seen significant commercial use since the 1930s, a challenge made more complicated by the fact that PFAS precursors can degrade from unregulated compounds to more commonly regulated ones.

Another challenge is that health-based toxicity values are relatively scarce, requiring conservative assumptions when determining risk. But what does this mean for organizations dealing with PFAS now?

First, staying current on the science is crucial both to understanding risk and applying recommendations. What we know about PFAS is evolving quickly and can impact risk evaluation.

Second, don’t assume that any recommendations are set in stone. Exposure frameworks, risk assessment frameworks, and even site closures may be subject to review as what we learn changes.

Finally, flexibility will be the watchword for risk assessment. Effective assessments will leave space for changing regulations, scientific growth, and new challenges. 

For more details, please read the paper at the Journal of the New England Water Works Association.

The Author:

John Oberer is a Senior Vice President/Principal and Licensed Site Remediation Professional (LSRP) at GZA with over 30 years of experience.  He has been involved in the investigation and remediation of soils and groundwater in both unconsolidated and bedrock aquifers at sites involving organic and inorganic contaminants as well as PFAS. These include projects where PFAS compounds are the primary and/or secondary contaminants in soil and groundwater and where there are potentially multiple sources of PFAS both on- and off-site.  John is a founding member of the New Jersey Licensed Site Remediation Professionals Association and has served on several NJDEP committees developing guidance for implementation of the LSRP program. Contact him at John.Oberer@GZA.com or 267.464.3616.