US EPA

In July 2023, the draft IRIS Assessment of Perfluorohexanesulfonic Acid (PFHxS) and Related Salts (Public Comment and External Review Draft) and the draft charge to external peer reviewers were released for a 60-day public review and comment period. The Toxicological Review and charge were reviewed internally by EPA and by other federal agencies and White House Offices before public release. Consistent with the May 2009 IRIS assessment development process, all written comments on IRIS assessments submitted by other federal agencies and White House Offices are made publicly available on this site.

Perfluorohexanesulfonic Acid (PFHxS) and its related salts are members of the group of per and polyfluoroalkyl substances (PFAS). PFAS are not naturally occurring in the environment; they are man-made compounds that have been used widely over the past several decades in consumer products and industrial applications because of their resistance to heat, oil, stains, grease, and water. Concerns about PFHxS and other PFAS stem from the resistance of these compounds to hydrolysis, photolysis, and biodegradation, which leads to their persistence in the environment.

PFHxS is used in water- and stain-protective coatings for consumer products such as carpets, textiles, paper (including food-contact), packaging (including food-contact), textiles, and electronics. It has been used industrially as a surfactant to make fluoropolymers, as a surfactant or surface protection agent for cleaning and polishing products, and in other industrial fluids or water-proofing agents. It may also be present unintentionally as an impurity from industrial production processes. PFHxS has also been used in aqueous film-forming foam (AFFF) for fire suppression.

EPA is undertaking development of the Integrated Risk Information System (IRIS) health assessment for PFHxS. The outcome of this project is an IRIS Toxicological Review and Summary for PFHxS will be entered into the IRIS database.

The Perfluorohexanesulfonic Acid (PFHxS) and Related Salts IRIS assessment was released for public comment in July 2023. Following the public comment period, there will be an external peer review. The assessment will then be revised taking into consideration public and peer review comments.

U.S. EPA. IRIS Toxicological Review of Perfluorohexanesulfonic Acid (PFHxS) and Related Salts (Interagency Science Consultation Draft, 2023). U.S. Environmental Protection Agency, Washington, DC, EPA/635/R-22/192, 2023.