Causation Issues in PFAS Litigation: Where Did the “Forever” Chemical Come From? | Schiffer Hicks Johnson

Per- and polyfluoroalkyl substances, also known as PFAS, are widely used synthetic chemicals. Often referred to as “eternal chemicals,” they have been subjected to rigorous scrutiny by the Environmental Protection Agency, other governments and agencies, and litigating parties.[1]

The EPA recently designated PFAS as hazardous substances,[2] exposing manufacturers to potential cleanup costs. Beyond this increased regulation, the litigation landscape continues to change dramatically. Lawsuits, including for alleged harmful exposures, have increased exponentially, and more are expected in the future. Some commentators already referring to PFAS as “the mother of toxic crimes” and the “next asbestos”,[3] it makes sense to move beyond whether the PFAS litigation is here to stay (it is) and consider what the contours of that litigation will look like.

More specifically, how will the parties attempt to prove or disprove causation? Veterans of asbestos litigation will recall endless depositions, with dozens of defendants asking plaintiffs rote questions about whether they remembered encountering this defendant’s products. Will the new science surrounding PFAS change the math? The answer is probably yes. Developments in PFAS research and tracking technology may significantly affect how parties can prove or disprove causal links between parties and their chemicals.


PFAS were developed in the 1930s, and during the 20e century have become nearly ubiquitous due to their remarkable ability to make surfaces resistant to oils and wrinkles. They are widely found in consumer goods, including non-stick food packaging, clothing, upholstery and cookware, and fire-fighting foams.[4] Humans ingest them through food, drinking water and household dust.[5]

As their use has grown, so have concerns about potentially negative health effects to humans and the environment.[6] The EPA has issued health advisories regarding safe and unsafe amounts of PFAS since at least 2016, but revised those advisories this year to indicate that PFAS can cause health risks at concentration levels far below what previously thought: 0.004 parts per trillion, instead of 70 ppt. .[7]

Different carbon-fluoride bond structures result in different types of PFAS, of which there are over 12,000 known today.[8] According to some, various PFAS have been associated with obesity, birth defects, impaired metabolism, fertility problems, ulcerative colitis, high cholesterol, developmental toxicity, enlarged liver, thyroid disease and various types of cancer including non-Hodgkin’s lymphoma, breast cancer, liver, kidney, testicular, prostate and ovarian cancers.[9] Others are considered relatively harmless.[10]

The EPA’s Proposed Rule and Ongoing Litigation

On August 26, 2022, the EPA proposed a new rule that would classify two widely used PFAS chemicals as hazardous substances under the Global Environmental Response, Compensation, and Liability Act (“CERCLA” or “Superfund”). ), which could expose PFAS manufacturers and users to liability for PFAS releases and cleanups. The EPA touts the rule as “increasingly[ing] transparency around the discharges of these harmful chemicals and help[ing] to hold polluters accountable for cleaning up their contamination.[11]

The proposed rule is, according to the EPA, prompted by new data and analysis suggesting that the levels at which PFAS can cause adverse health effects are significantly lower than previously understood.[12]The CERCLA designation would require anyone responsible for a vessel or facility to report releases of PFOA and PFOS of one pound or more within 24 hours of the release. It would also require federal agencies to disclose the presence of hazardous substances, including PFOA and PFOS, at the scene.[13]

The proposed settlement comes amid a dramatic growth in the breadth and depth of litigation against companies that have widely used PFAS in manufacturing, as well as the expansion of the types of parties that bring such lawsuits, from individuals to municipalities and states.[14] A federal judge presiding over multidistrict PFAS litigation has pointed out that such litigation poses “an existential threat” to companies as massive as 3M and EI du Pont de Nemours and Co.[15]

For example, the Commonwealth of Massachusetts sued 13 companies, including 3M and Du Pont, for violations of the Massachusetts Safe Drinking Water Act and Consumer Protection Act, as well as liability for products, negligence, public nuisance and trespass.[16] The Kalispel Indian Tribe sued 3M Co., Tyco Fire Products LP and the United States, alleging that the fire-fighting foam contaminated their drinking water.[17] The City of San Diego has sued more than 20 chemical companies for “consistently manufacturing and covering up the toxic nature of fire-fighting foams that have contaminated drinking water supplies around San Diego for decades.”[18]

Tracking where the PFAS came from

Historically, plaintiffs alleging damages based on contamination with hazardous substances (most often asbestos) have invoked various theories of liability where it is impossible to identify the specific manufacturer or supplier of the hazardous substance. .[19] As commentators observed years before the EPA’s proposed rule, CERCLA’s imposition of joint and several liability between liable parties could put chemical companies sued for contamination in the unenviable position of having to prove that they did not manufacture any of the PFAS at the alleged site.[20]

As litigation issues and regulations surrounding PFAS grow, efforts in the field of environmental forensics to track PFAS to their source are increasing.[21] Tracking PFAS is complicated by the fact that the types of PFAS in a given product are usually proprietary information. Nonetheless, information gained from the types and percentages of PFAS found in a given sample can allow researchers to identify the original manufacturing process or product. Whether the composition of a PFAS molecule is “branched” or “linear”, the distribution of consecutive perfluorinated carbons and formation at the end of a given PFAS chain can indicate the manufacturing process that caused this molecule.[22] These data points can collectively provide an imperfect “fingerprint” identifying the manufacturing process from which the contaminant originated, providing litigants with more information to use to argue for or against the attribution of liability.

As the scientists explained, several lines of data can be brought together to identify the sources of PFAS that are identified, whether in water, sediment or soil.[23] No tool can be used to discover their sources, but it can be done using a holistic course of scientific action.[24] This includes a combination of analytical chemistry, PFAS fate and transport, analysis of site-specific conditions, graphical analysis and statistical methods.[25] This will require lawyers to engage a multidisciplinary team of experts that covers chemistry, hydrogeology, fate and transport.

As environmental forensic methods for tracking PFAS continue to develop, litigants will need to understand these methods when considering how to prove or disprove liability and causation. Now that it’s clear that PFAS litigation is here to stay, this kind of scientific evidence will be essential for years to come.




















[20] See, for example,