Per- and polyfluoroalkyl substances (PFAS) are a group of synthetic chemicals that have been used extensively since the 1940s to make coatings such as Teflon®, Scotchgard®, and Gore-Tex® for products like cookware, food packaging, stain and water repellants, as well as firefighting foams. In the past couple of years, drinking water concerns have been raised over the known/suspected toxicity of PFAS, and research has focused on sample analysis, remediation, and better toxicological assessment of these chemicals.
Longer-chained perfluoroalkyl acid (PFOA) and perfluorooctane sulfonate (PFOS) are currently the only PFAS with Environmental Protection Agency (EPA) Drinking Water Health Advisory levels and have generally been phased out of production in the U.S. due their high potential for human health and environmental impacts. As government agencies work to address PFAS, the EPA recently published a fact sheet and draft toxicity assessments for two types of shorter-chained and less environmentally harmful PFAS: GenX and perfluorobutane sulfonic acid (PFBS). Furthermore, EPA updated one of the analytical methods for PFAS.
A little background on GenX and PFBS
GenX is a trade name for a technology that is used to make high performance fluoropolymers for some nonstick coatings, without the use of PFOA, by using the hexafluoropropylene oxide (HFPO) dimer acid and its ammonium salt. PFBS and its related compound potassium perfluorobutane sulfonate (PPBS) replaced PFOS and other longer-chained PFAS.
GenX chemicals and PFBS can travel in the environment and impact drinking water based on surface water and groundwater contamination. Humans may also be exposed through other pathways, including through ambient air and consumption of food packaged in products made with PFAS such as fast food wrappers and microwavable popcorn bags.
EPA’s new updates on GenX and PFBS chemical toxicity
On November 21, 2018, the EPA published draft human health toxicity assessments for GenX chemicals and for PFBS in the Federal Register. The assessment explains that “overall, the available oral toxicity studies show that the liver is sensitive to GenX chemicals, and the kidney and thyroid are sensitive to PFBS.” However, the draft assessments suggest that GenX chemicals are 4 times less toxic, and PFBS are 500 times less toxic than PFOA and PFOS, whose drinking water health advisory was summarized in this 2016 EPA fact sheet.
Based on the limited knowledge base about GenX and PFBS, EPA states that the draft toxicity values for these chemicals may change in the future. Interested parties can provide input on the draft assessment during the 60-day comment period. Trihydro will be reviewing and commenting on EPA’s draft document.
Ask us your PFAS questions!
If you have questions or want to know more, please contact us:
Andrew Pawlisz, D.A.B.T.
Senior Program Specialist, Toxicology
Rajib Sinha, P.E.
Senior Engineer, Regional Development Manager