Perfluorooctanoic acid (PFOA), also known as C8, and perfluorooctanesulfonic acid (PFOS) are a class of perfluorinated carboxylic acids (PFCs) that have generated much interest in the last two decades due to media attention and an awareness of its extreme persistence (long biologic half-life). These chemicals were historically used in Teflon related products and textiles. History has shown that these chemicals, which were used for stain resistance, contaminate the groundwater across the nation where an industry which used them is nearby. More recently, concern about firefighters who were exposed via foam has been expressed. 

Paustenbach and Associates has been involved with these group of chemicals since the early 2000s and has been continuing work understand their effects. We have evaluated occupational exposures to PFOA/PFOS and the effects of its release to groundwater. For example, we were among the first to recognize that water from factories that treated fabrics and carpets was a source of contamination of groundwater due to the distribution of sludges from the local water treatment facility have been applied on to farmlands.

Key Projects

  • Characterized the hazard posed by PFOA to water bodies. Since the late 1990s and early 2000s, we have been studying the fluorinated chemicals with respect to the toxicological hazard and the fate/transport in the environment.  In 2015, we were asked to investigate the possible hazard associated with the contribution of textile factories to the contamination of sludges in wastewater treatment plants.  This is a highly complex issue that captured the attention of the media and trial lawyers since approximately 2014.
  • Assessed the risk associated with PFOA or PFOS in MSWTP sludges. We evaluated the threat to groundwater of using sludges from water treatment plants as soil amendment in farm fields. This practice was apparently common in Alabama and Mississippi where there were textile mills treating carpets with stain repellents (fall 2011).
  • Assessment of perfluorooctanoic Acid (PFOA) in groundwater (West Virginia). In 2003, ChemRisk was retained by DuPont to characterize the human health hazards posed by various concentrations of PFOA in groundwater, ambient air, soil, and other media near their Parkersburg manufacturing site. The work was completed in 2005, and is currently being reviewed by USEPA. The analysis was published in a peer-reviewed scientific journal, presented at the First International Symposium on Fluorinated Alkyl Organics in the Environment (Toronto, Canada) in August 2005, and is considered an important and unique study.
  • PFOA in groundwater: We conducted an analysis that explained why groundwater many miles from a facility could become contaminated via aerial deposition (Paustenbach, D.J., J.M. Panko, P.K. Scott and K.M. Unice. 2007. A methodology for estimating human exposure to perfluorooctanoic acid (PFOA): A retrospective exposure assessment of a community (1951-2003). J Toxicol Environ Health A. 70(1):28-57). This was the first occasion where any aerially distributed chemical was found to be able to reach groundwater. The EPA, NGOs, and various professors were surprised that we made the connection and that we reported our data in a journal. Three major universities were hired by EPA to check whether our methodology and conclusions were correct; and they confirmed the results of our analyses (Shin H.M., V.M. Vieira, P.B. Ryan, R. Detwiler, B. Sanders, K. Steenland, and S.M. Bartell. 2011. Environmental fate and transport modeling for perfluorooctanoic acid emitted from the Washington Works Facility in West Virginia. Environ Sci Technol. 15:45(4):1435-42.)
  • PFOA in groundwater due to the use of water treatment sludges as soil amendments: We had been asked to evaluate whether sludge’s from former carpet and clothing treating facilities, when applied to the soil could contaminate groundwater. We concluded that in some cases, where the water table was shallow, this could occur. A published paper by an environmental advocacy group applauded us for our work on the PFCs (Lerner, S. 2015. The Teflon Toxin, from This incident was memorialized in the movie Dark Waters (released in Dec. 2019).


  • Paustenbach, D.J., J.M. Panko, P.K. Scott and K. M. Unice. 2006. A methodology for estimating human exposure to perfluorooctanoic acid (PFOA): A retrospective exposure assessment of a community (1951-2003). J Toxicol Environ Health. 70:28-57.


  • 2024 (Jan. 22). Lessons Learned From 20 Years Of Study Of The Dioxins: Can It Help Inform EPA In Setting An MCL For PFOS/PFOA? Shubik Lecture at the Toxicology Forum Meeting. Washington, DC.
  • 2023 (Oct. 17). Dioxins vs. PFOA/PFOS: Similarities and Differences. Presentation at the Beyond Science and Decisions TERA Workshop XIV: PFAS Limits: How Did We Get So Far Apart? Conference. Washington, DC.