Forever Chemicals, Documented Since 2005: PFAS Fate, Transport, and Firefighter Exposure
By Paul E. Rosenfeld, M.S., Ph.D., Principal Environmental Chemist, RoseyFields LLC, Santa Monica, California
A twenty-year record on a contaminant class regulators are still catching up to
Per- and polyfluoroalkyl substances (PFAS) attracted mainstream litigation attention largely in the 2010s and 2020s, but Dr. Paul E. Rosenfeld, M.S., Ph.D. of RoseyFields LLC was presenting on PFOA fate, transport, and toxicology as early as 2005, giving his current PFAS litigation work an unusually long documented professional foundation (Rosenfeld, 2005a; Rosenfeld, 2005b).
Aqueous film-forming foam as a PFAS source
One of the best-documented PFAS exposure pathways is aqueous film-forming foam (AFFF), historically used for fighting petroleum-based fires at airports, military bases, and industrial facilities, which released PFOA and PFOS directly into soil and groundwater at application sites. Dr. Rosenfeld presented specifically on PFOA and PFOS contamination in drinking water from AFFF use at U.S. airports (Rosenfeld, 2009).
AFFF manufacturer litigation
That specialized background is directly relevant to litigation against AFFF and PFAS manufacturers, including consolidated federal litigation against 3M Company arising from PFAS contamination (Bells, 2018), where fate-and-transport analysis of how PFAS chemicals migrate from an application or manufacturing site into groundwater and drinking-water supplies is central to establishing a pathway from a defendant’s product to a plaintiff’s exposure.
Firefighters as a uniquely exposed occupational population
Beyond environmental releases, firefighters face direct occupational PFAS exposure through AFFF use and through PFAS-treated turnout gear. Dr. Rosenfeld and coauthors published a peer-reviewed review of PFAS exposure sources and implications specifically for firefighters, addressing both the AFFF and protective-equipment pathways in a single analytical framework (Rosenfeld et al., 2023).
Responding to scientific critique in the peer-reviewed literature
That firefighter PFAS paper subsequently drew a published critique, to which Dr. Rosenfeld and a coauthor responded directly in the same journal, addressing the specific methodological questions raised (Rosenfeld & Spaeth, 2023). Publishing both the original analysis and the response to critique in the peer-reviewed literature, rather than only in litigation reports, subjects the underlying methodology to a level of scrutiny litigation reports alone do not receive.
The current federal drinking-water standard
In April 2024, EPA finalized the first federal Maximum Contaminant Levels for PFAS in drinking water, setting individual limits of 4.0 parts per trillion for both PFOA and PFOS, along with limits for four additional PFAS compounds and a Hazard Index approach for their mixtures (US EPA, 2024). That rulemaking reflects a regulatory judgment that PFOA and PFOS are unsafe at extraordinarily low, single-digit parts-per-trillion concentrations.
A regulatory landscape still in motion
EPA’s PFAS drinking-water framework remains subject to ongoing rulemaking; in 2026 the agency proposed both a compliance-timeline extension for the PFOA/PFOS limits and a separate action affecting the individual limits and Hazard Index for several other PFAS compounds (US EPA, 2026). Litigation reports addressing PFAS exposure should track this evolving regulatory posture rather than treat any single year’s standard as final.
Why fate and transport, not just toxicology, decides these cases
PFAS compounds are highly persistent and mobile in groundwater, meaning contamination detected at a monitoring well may have originated from a source and time period far removed from the sampling date. Reconstructing that transport pathway, from a manufacturing or firefighting-training site, through soil and groundwater, to a drinking-water intake, requires the same fate-and-transport modeling skill set Dr. Rosenfeld has applied across other contaminant classes for over two decades.
Connecting the environmental pathway to the occupational pathway
In firefighter-specific matters, both pathways can be relevant simultaneously: environmental PFAS contamination in a fire station’s water supply and occupational PFAS exposure from turnout gear and AFFF use during the same career. Dr. Rosenfeld’s firefighter PFAS publication specifically integrates both source categories into a single exposure framework rather than treating them as unrelated (Rosenfeld et al., 2023).
Regulatory-grade methodology applied to an emerging contaminant
As with his other chemical classes, Dr. Rosenfeld’s PFAS work draws on established EPA and ATSDR exposure-assessment methodology applied to a comparatively new regulatory subject, giving PFAS litigation the same evidentiary structure, source characterization, fate and transport, dose reconstruction, and regulatory benchmarking, that courts have found reliable in his other chemical-specific work.
Why PFAS litigation will remain a growth area
With federal drinking-water limits now in the low parts-per-trillion range and additional PFAS compounds under active regulatory review, the population of plaintiffs with a documented PFAS exposure pathway is likely to continue growing well beyond current AFFF and manufacturing-site litigation. Additional background on Dr. Rosenfeld’s PFAS-specific work appears at RoseyFields.com.
References
1. Bells RL, et al. v The 3M Company, et al. Case No. 1:16-cv-02531-RBJ (D Colo).
2. Rosenfeld PE. Fate, Transport and Persistence of PFOA and Related Chemicals. Mealey’s C8/PFOA Science, Risk & Litigation Conference; October 24-25, 2005; Philadelphia, PA.
3. Rosenfeld PE. Fate Transport, Persistence and Toxicology of PFOA and Related Perfluorochemicals. National Groundwater Association Ground Water and Environmental Law Conference; July 21-22, 2005; Baltimore, MD.
4. Rosenfeld PE. Perfluoroctanoic Acid (PFOA) and Perfluoroactane Sulfonate (PFOS) Contamination in Drinking Water From the Use of Aqueous Film Forming Foams (AFFF) at Airports in the United States. Ground Water Summit and Ground Water Protection Council Spring Meeting; April 19-23, 2009; Tucson, AZ.
5. Rosenfeld PE, Spaeth KR, Remy LL, Byers V, Muerth SA, Hallman RC, Summers-Evans J, Barker S. Perfluoroalkyl substances exposure in firefighters: sources and implications. Environ Res. 2023;220:115164.
6. Rosenfeld PE, Spaeth KR. Authors’ response to letter to the editor from Bullock and Ramacciotti. Water Air Soil Pollut. 2023;234:165.
7. US Environmental Protection Agency. PFAS National Primary Drinking Water Regulation. 40 CFR Parts 141 and 142. Fed Regist. 2024;89(81):32532-32757.
8. US Environmental Protection Agency. Per- and Polyfluoroalkyl Substances (PFAS): Proposed PFOA and PFOS Compliance Extension Rule. Washington, DC: US EPA; 2026.
9. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Perfluoroalkyls. Atlanta, GA: US Department of Health and Human Services; 2021.
10. US Environmental Protection Agency. Human Health Toxicity Assessment for Perfluorooctanoic Acid (PFOA) and Related Compounds. Washington, DC: US EPA; 2024.
11. Rosenfeld PE. RoseyFields LLC: PFAS Fate, Transport, and Exposure Assessment. Santa Monica, CA: RoseyFields LLC; 2026.
12. US Environmental Protection Agency. Toxicological Review of Benzene (Noncancer Effects). Integrated Risk Information System (IRIS). Washington, DC: US EPA; 2003.
13. IARC Working Group on the Evaluation of Carcinogenic Risks to Humans. Benzene. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol 120. Lyon, France: International Agency for Research on Cancer; 2018.
14. US Environmental Protection Agency. Revisions to the Guideline on Air Quality Models. 40 CFR Part 51, Appendix W. Fed Regist. 2017;82(10):5182-5235.