PFAS are challenging contaminants because most PFAS constituents cannot be detected using conventional analytical techniques. Remediation options that may address one PFAS constituent may not work for others, and only partial treatment may be achievable. Byproducts of treatment may not be detected and thus their risk is unknown. Risk-based standards for PFAS in soil and water are extremely low.

Investigation and management of PFAS sites require an innovative, adaptable and educated team, actively involved in (not just aware of) current research, and capable of developing and optimizing new approaches in response to policy updates and technological advances.

What are PFAS?

PFAS, formerly known as "perfluorinated compounds" (PFCs), are emerging compounds of increasing importance for a broad spectrum of industrial sites and waterways. PFAS are a family of organic substances whose molecular structures contain multiple fluorine (F) atoms in place of hydrogen (H) atoms. Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are the two most widely-recognized, environmentally-relevant PFAS, although there are hundreds of PFAS of potential significance, and little is known about these compounds.

Why are PFAS so Challenging?

The sources of PFAS in the environment (e.g., Aqueous Film Forming Foam [AFFF] or misting for electroplating) are typically comprised of complex mixtures of hundreds of individual PFAS constituents. The majority of PFAS constituents cannot be detected using conventional analytical techniques. Progress is being made towards developing analytical techniques to improve the detection of these constituents, including recent research by Geosyntec and partners developing nuclear magnetic resonance (NMR)-based analytical techniques and total fluoride field screening, but it may be years before comprehensive site characterization is achievable. The behavior of PFAS constituents in the environment can also vary widely depending on the composition of the PFAS mixture, the presence of co-contaminants, the introduction of oxidants or reductants into the environment. Maintaining fluoride mass balance while monitoring byproducts of degradation reactions is critical to understanding remedial success, but is currently difficult to achieve. As such, it is essential that knowledgeable practitioners, who fundamentally understand the limitations and challenges associated with PFAS, direct investigation and remediation efforts to achieve successful mitigation of risk at PFAS sites.