Compounds that do not break down, in a regulatory framework that will not sit still. Both facts shape every matter involving them.
Start a conversation with our AI Research Concierge, already scoped to PFAS & AFFF. Pick a starting point, or describe your situation directly.
PFAS are a class of thousands of synthetic compounds distinguished by carbon-fluorine bonds strong enough that they do not meaningfully degrade in the environment or in the body. That single property drives most of what makes them difficult: plumes travel further and persist longer than conventional attenuation models predict, exposure accumulates over time, and remediation cannot rely on degradation. Aqueous film-forming foam used in firefighting and fire training is among the most significant identified sources, and AFFF litigation consolidated as MDL-2873 has become one of the largest active toxic tort dockets in the country. The regulatory picture is unusually unsettled, which affects both compliance obligations and how standards can be used as evidence.
Each of these differs materially from how a conventional solvent or petroleum matter behaves.
Carbon-fluorine bonds resist degradation, so plumes do not attenuate on the timescales that solvent work assumes.
A class, not a chemical. Most individual compounds lack toxicological characterisation, and analytical suites capture only a fraction.
Firefighting foam at airports, military installations, refineries and training grounds — a well-documented and geographically concentrated source type.
Ingestion via public and private supply is the dominant exposure route in most community matters.
Long human half-lives mean serum concentrations reflect cumulative exposure, which changes what biomonitoring can show.
Federal drinking water standards are being actively reconsidered while litigation proceeds around them.
How PFAS matters are worked up.
The scale is unusual: sources are often institutional, plumes are wide, and affected populations are large.
On 18 May 2026 EPA proposed to keep the PFOA and PFOS maximum contaminant levels while extending compliance to 2031, and separately to rescind the regulatory determinations for PFHxS, PFNA, GenX and the Hazard Index mixture. Comments closed 20 July 2026 and nothing is final. Verify the current position before relying on any figure — and expect states to diverge from the federal position.
It is genuinely in flux, and any answer needs a date attached. EPA finalised maximum contaminant levels for several PFAS in 2024. In May 2026 it proposed two changes: retaining the PFOA and PFOS limits but extending the compliance deadline by two years to 2031, and rescinding the regulatory determinations for PFHxS, PFNA, HFPO-DA and the Hazard Index mixture that included PFBS. The comment period closed in July 2026 and the proposals were not final at the time of writing. Several states have their own standards, and where the federal position is contracting, state requirements are where the operative obligation increasingly sits.
The evidence base is strongest for certain cancers — kidney and testicular cancer are the associations most frequently identified as best supported in the AFFF context, and they feature prominently in how that litigation has been organised. Other outcomes have been alleged with a range of evidentiary support. As with any general causation question, what a matter requires is a defensible assessment of the whole literature for the specific compound and the specific disease, at exposure levels resembling those alleged, rather than reliance on the class as a whole.
Because the compounds are in ordinary materials that field work involves — certain waterproof clothing, some sample containers and tubing, adhesives, and even some personal care products used by samplers. Concentrations of interest are extremely low, so trace introduction from equipment or the sampler produces false positives at levels that matter. Field and equipment blanks, prohibited-materials lists and dedicated protocols exist for this reason, and a sampling programme that did not follow them is an obvious line of attack on the resulting data.
Through compound profile and site history together. Different sources produce characteristically different mixtures — AFFF formulations differ from those associated with industrial manufacturing, biosolid application or landfill leachate, and the relative proportions of individual compounds carry information about origin. Because these compounds do not degrade, the profile is more stable over time than for substances that break down, which helps attribution. Where sources overlap the analysis may resolve to proportions rather than a single origin.
Describe the source and the claim. We will scope it and connect you with the right expert.