Per- and polyfluoroalkyl substances (PFAS) are a large group of synthetic chemicals used in a variety of everyday materials, including nonstick cookware, carpet, textiles, high-performance outdoor gear, coated paper and cardboard products, some firefighting foams, and a variety of cleaning products, paints, varnishes, and sealants. These compounds repel oil, water, grease, and stains, resist temperature extremes, and reduce friction. PFAS have been in use since the 1940s.
PFAS are characterized by a chain of fluorine-carbon bonds, among the strongest bonds in chemistry. Their persistence in the environment has earned them the distinction of being “forever chemicals” because they don’t naturally degrade in soil or water. Due to their persistence in the environment and widespread use, most people in the United States have been exposed to PFAS.
Over 4,000 different PFAS have been identified through analytical detection, studies, and manufacturing process data, with at least 1,000 more PFAS-named substances that may fall within its broad chemical definition.
Long-chain PFAS compounds consisting of 8 or more carbon atoms have stronger chemical bonds than shorter-chain PFAS compounds, meaning the chemicals are more likely to accumulate in the bodies of humans and wildlife and not degrade in the environment. Long-chain compounds include:
- Perfluorooctanoic acid (PFOA)
- Perfluorooctane sulfonic acid (PFOS)
- Perfluorononanoic acid (PFNA)
- Perfluorohexane sulfonic acid (PFHxS)
- Perfluordecanoic acid (PFDeA)
The Environmental Protection Agency (EPA) was concerned about the adverse health and environmental effects of long-chain PFAS, particularly PFOA and PFOS, two of the most widely studied PFAS compounds. Both PFOA and PFOS were detected in the blood serum of up to 99 percent of samples collected between 1999 and 2012 in a representative population of the United States.
Some U.S. manufacturers voluntarily phased out production of PFOA and PFOS beginning in 2004. The eight major PFAS manufacturing companies committed to reducing PFOA and other long-chain PFAS compounds under EPA’s PFOA Stewardship Program. EPA indicated that all eight companies had eliminated their manufacture by 2015. The phase-out resulted in decreasing levels of these two compounds in blood serum and bio-monitoring studies. However, long-chain PFAS are still manufactured in other parts of the world and may be present in imported products.
Many long-chained PFAS have since been replaced with short-chain PFAS. These compounds were initially believed to be less toxic and less persistent in the environment. Unfortunately, these short-chain alternatives have proven to be as persistent in the environment as their long-chain counterparts, with different but no less concerning health and environmental impacts. While these short-chain PFAS have received less attention and regulatory oversight than long-chain chemicals such as PFOA and PFOS, scientists are now raising concerns about the harmful impacts of this new generation of PFAS compounds. Short-chain PFAS are more difficult to remove from drinking water and have a greater potential for long-range transport. Short chain PFAS compounds include:
- GenX chemicals (replaced PFOA)
- Hexafluoropropylene oxide (HFPO) dimer acid
- Ammonium salt of HFPO dimer acid
- Perfluorobutanesulfonic acid (PFBS) (replaced PFOS)
The switch from long-chain to short-chain PFAS led to an increase in their presence in humans and the environment. Animal studies on GenX chemicals have shown health effects in the kidney, blood, immune system, developing fetus, and especially in the liver following oral exposure. The data are also suggestive of cancer. Animal studies on PFBS have shown health effects on the thyroid, reproductive organs and tissues, developing fetus, and kidney following oral exposure. Overall, the thyroid and kidney are particularly sensitive to PFBS.
The potential for long-term health effects, exposure from contamination in agricultural products and fish, difficulties with treating drinking water, (etc), and unknown potential for bio-accumulation in humans and wildlife point to continuing concerns about the long-term impacts of these newer chemicals.
Regulatory Response to PFAS
Although there are a number of federal laws and regulations that could be eventually used to control PFAS contamination, EPA has not yet issued enforceable standards for these chemicals.
The EPA has set a lifetime health advisory limit (LHA) of 70 parts per trillion (70 ppt) for PFOS and PFOA under the Safe Drinking Water Act (SDWA), but the agency has not set Maximum Contaminant Levels (MCLs) for these compounds, an action that would require routine monitoring of public water supplies. PFAS are not currently listed as hazardous substances under the Comprehensive Environmental Response Compensation and Liability Act (CERCLA). No PFAS compounds are listed as hazardous wastes under the Resource Conservation and Recovery Act, nor are they regulated under the Toxic Substances Control Act. PFAS compounds are not listed as toxic or priority pollutants under the Clean Water Act.
EPA has developed a Per- and Ployfuoroakyl Substances (PFAS) Action Plan to increase understanding of PFAS compounds and their effects on human health and the environment, identify methods to clean up contaminated sites, and develop tools to prevent future contamination. Proposed actions:
- Expand toxicity information for PFAS.
- Develop new tools to characterize PFAS in the environment.
- Evaluate cleanup approaches.
- Develop guidance to facilitate the cleanup of contaminated groundwater.
- Use enforcement tools to address PFAS exposure in the environment and assist states in enforcement activities.
- Use legal authorities such as those in the Toxic Substance Control Act (TSCA) to prevent future PFAS contamination.
- Address PFAS in drinking water through regulatory and other methods.
In addition, EPA announced four new regulatory approaches to address PFAS contamination:
- Initiate steps to evaluate the need for a maximum contaminant level (MCL) for PFOA and PFOS.
- Begin the necessary steps to designate PFOA and PFOS as “hazardous substances” through available federal statutory mechanisms.
- Develop groundwater cleanup recommendations for PFOA and PFOS at contaminated sites.
- Developing toxicity values or oral reference doses (RfDs) for GenX chemicals and PFBS.
Congressional lawmakers have introduced, or plan to introduce, legislation to address a range of PFAS-related concerns, from the requirement for EPA to establish an MCL for PFAS in drinking water to laws that prevent new PFAS chemicals from being approved under the TSCA.
A number of states concerned about the slow response to develop enforceable regulations for PFAS contamination have either adopted or introduced regulations and policies to address PFAS in drinking water, landfills, firefighting foams, cosmetics, and food packaging. California has adopted nonbinding drinking-water notification levels of 13 parts per trillion (ppt) for PFOS and 14 ppt for PFOA, and New Jersey has proposed to use these same levels as state drinking-water standards for PFOS and PFOA. Vermont has set a 20 ppt drinking water health advisory for any combination of five PFAS and plans to propose 20 ppt as the MCL for these PFAS compounds. Other states, including Alabama, California, Illinois, Massachusetts, Mississippi, Montana, New Hampshire, New York, North Carolina, Pennsylvania, and Wisconsin, are considering similar steps.