What do non-stick coated pans, waterproof fabrics, oil-resistant food packaging, stain-resistant materials, and fire-fighting foam all have in common? They all potentially contain fluorinated compounds, and more specifically, are made with a suite of specialty chemicals called Perfluorooctanesulfonic acid (PFOS) and Perfluorooctanoic acid (PFOAs). PFOs and PFOAs both are fluorinated organic chemicals, part of a larger family of compounds referred to as Perfuoroalkyl Substances (PFAS). These substances are synthetic compounds that are unique for being water and lipid-resistant.
PFAS have been identified as one of the leading “emerging contaminants” by U.S. EPA. In May 2016, the United States Environmental Protection Agency (US EPA) released two documents titled Health Effects Support Document for Perfluorooctanoic Acid (PFOA) and Health Effects Support Document for Perfluorooctane Sulfonate (PFOS). The U.S. EPA is required, “…to publish a list of unregulated microbiological and chemical contaminants known or anticipated to occur in public water systems and that might require control in the future through national primary drinking water regulations.” PFOA and PFOS are two of the chemicals identified on the EPA’s Contaminant Candidate List (CCL), which means they were chosen for regulatory decision making and information collection. PFOAs and PFOSs go against the common misconception that “emerging contaminants” are chemicals that have only recently been released into the environment. Instead, they have the potential to have been released over 60 years ago, and we are only now discovering them in our water supply and more fully understanding their toxicological effects and practical and regulatory implications.
Historically, both 3M and the DuPont corporations were the major producers of PFOA. 3M began manufacturing PFOA in the 1940s, and DuPont began using PFOA in the 1950s. In 2000, 3M began phasing out production of PFOA and related compounds, and in 2002 DuPont built its own PFOA manufacturing plant in North Carolina. In 2006, eight major corporations, including 3M and DuPont, voluntarily agreed to phase out their global production of PFOA and PFOA-related chemicals with total elimination of these chemicals by the end of 2015. EPA has an opportunity to review any effort to reintroduce the chemical into the market place under the proposed Toxic Substance Control Act’s Significant New Use Rule (SNUR).
PFOA and PFOS are persistent chemicals, meaning they are stable in the environment and do not breakdown readily, and are not readily eliminated from the human body. They are both resistant to high temperatures, are water and dirt repellent, and grease proof. Because of this, they have historically been used in surface treatments for soil/stain resistance on carpets, textiles, leather, paper and cardboard (for food packaging), metals, and also a surfactant in fire extinguisher and fire-fighting foams. Large amounts of PFOA were used industrially as a processing aid in the production of fluoropolymers and fluoroelastomers for use as non-stick coatings (i.e., Teflon™). In addition, fire-fighting training areas on military bases and other training facilities have been a common source of the PFAS contamination to drinking water sources.
Potential toxicological effects of PFAS have been studied for some time, but are just now getting more closely scrutinized. Studies have shown that elevated exposure to PFAS can potentially result in liver, immunological, developmental, endocrine, and reproductive effects, as well as cancer. The common human exposure pathways associated with these compounds is contact at the work place, ingestion of food containing PFAS (including fish), drinking water contaminated with PFAS, and direct contact with treated fabrics. In addition, PFAS can bio-accumulate in fish and wildlife. As such, fish advisories for PFAS have been issued by some states, and in one county in Michigan, there is a Do Not Eat advisory for deer.
A Maximum Contaminant Level (MCL), the legal threshold limit on the amount of a substance allowed in public water systems under the Safe Drinking Water Act, has not been established for PFOA or PFOS. In November 2016, however, the U.S. EPA issued a Fact Sheet titled PFOA & PFOS Drinking Water Health Advisories. According to the Fact Sheet, when both PFOA and PFOS concentrations are detected in drinking water, the combined concentrations should be compared to a health advisory level of 70 parts per trillion (ppt). To put this into perspective, the currently established MCL for benzene (petroleum compound) and tetrachloroethylene (common dry cleaning solvent) is 5,000 parts per trillion.
At least 10 states (CA, CT, ME, MA, MI, NH, NJ, NC, VT, and WV) currently have guidance levels established for PFAS. The most conservative is the New Jersey Department of Environmental Protection, which published (June 27, 2016) a PFOA water standard of 14 ppt based on their State’s research and the need for a standard because of the contaminant’s prevalence in the State’s drinking water. Most of the other states adopted the U.S. EPA’s health advisory level, or some value between 14 ppt (NJ) and 70 ppt (U.S. EPA). Some states like Michigan, have enacted a very aggressive statewide PFAS drinking water sampling program, which includes sampling of all schools on well water, and all community water systems.
Sampling protocols for PFAS in soil, groundwater, and sediment are very specific due to the ubiquity of the chemicals on the people doing the sampling (e.g., water-proof, stain resistant fabrics, Goretex boots, etc.) and in typical environmental sampling supplies (many sampling components contain Teflon or similar compounds). These factors, coupled with the very low detection levels and regulatory levels (ppt), result in increased potential of cross-contamination during sampling. As such, there are well established sampling protocols for PFAS. In the last 3 months, Michigan published nine (9) different sampling guidance documents for PFAS. The documents include guidance for sampling groundwater, surface water, wastewater, soils, residential wells, sampling and lab information, and general and quick-reference guides. Other states have similar guidance, and we have seen that labs are developing sampling procedures too.
Remedial options for PFAS and related compounds in soils include excavation and landfilling or off-site incineration. Some field applications of in situ soil stabilization approaches (using activated carbon, alumina or kaolinite) have shown some promise, and soil washing and thermal are currently developing technologies. Remediation of PFAS in water is largely associated ex situ (i.e., pump and treat) technologies, including carbon adsorption, resin adsorption, and reverse osmosis. Technologies currently being evaluated for in situ groundwater/water treatment include sorption using injected nano- scale carbon and biopolymer. Based on the chemical properties of PFAS, the traditional groundwater/water treatment approaches of air stripping, air sparging, bioremediation, and chemical oxidation have not yet been shown to be highly effective. We anticipate that the advances in remedial technologies will increase as the regulatory interest continues to grow. Contamination associated with PFAS is a growing concern for regulators and the regulated community. As more states develop screening and/or clean-up criteria, the overall state of the science will expand significantly.