IRIS Toxicological Review of Perfluorohexanesulfonic Acid (Pfhxs) and Related Salts (Interagency Science Discussion Draft, 2024)
In January 2025, EPA finalized the IRIS Toxicological Review of Perfluorohexanesulfonic Acid (PFHxS) and Related Salts. The Toxicological Review was reviewed internally by EPA and by other federal agencies and White House Offices after public release in July 2023. 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.
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.
Impact/Purpose
Now that the interagency review draft has been completed and finalized, the final Perfluorohexanesulfonic Acid (PFHxS) assessment has been loaded into the IRIS Web site and Database.Citation
U.S. EPA. IRIS Toxicological Review of Perfluorohexanesulfonic Acid (Pfhxs) and Related Salts (Interagency Science Discussion Draft, 2024). U.S. Environmental Protection Agency, Washington, DC, EPA/635/R-24/0326, 2024.History/Chronology
| Date | Description |
|---|---|
| 01- Nov 2019 | EPA released the Systematic Review Protocol for the PFHxS IRIS Assessment (Preliminary Assessment Materials). [Federal Register Notice Nov 8, 2019] |
| 02- Jul 2020 | EPA released an update to the Systematic Review Protocol for the PFBA, PFHxA, PFHxS, PFNA, and PFDA IRIS Assessments in response to public comments. |
| 03- Jan 2023 | EPA sent an interagency science consultation PFHxS draft for review and comment. |
| 04- Jul 2023 | EPA released the draft IRIS Toxicological Review of Perfluorohexanesulfonic Acid (PFHxS) and Related Salts for a 60-day public comment period and external peer review. EPA also released the interagency science consultation comments from reviewers. [Federal Register Notice: July 24, 2023] |
| 05- Feb/Mar 2024 | ERG, an independent contractor to the EPA, hosted multiple external peer review meetings for the review of the Integrated Risk Information System (IRIS) Assessment for PFHxS in late Febraury and early March. |
| 06- Jul 2024 | EPA posted the final peer review report from the contractor on the EPA website. |
| 07- Nov 2024 | EPA submitted the revised interagency science discussion draft for final Agency and Interagency review. |
Download(s)
This download(s) is distributed solely for the purpose of pre-dissemination peer review under applicable information quality guidelines. It has not been formally disseminated by EPA. It does not represent and should not be construed to represent any Agency determination or policy.
- ATSDR PFHxS IASD Comments November 2024 (PDF) (2 pp, 194.3 KB, about PDF)
- DOD PFHxS IASD Comments November 2024 (PDF) (9 pp, 297.9 KB, about PDF)
- CEQ PFHxS IASD Comments November 2024 (PDF) (3 pp, 198.2 KB, about PDF)
- USDA PFHxS IASD Comments November 2024 (PDF) (1 pp, 130.9 KB, about PDF)
Related Link(s)
- Systematic Review Protocol for the PFAS IRIS Assessments (2021)
- Systematic Review Protocol for the Perfluorohexanesulfonic Acid (PFHxS) IRIS Assessment (Preliminary Assessment Materials)
- IRIS Toxicological Review of Perfluorohexanesulfonic Acid (PFHxS) and Related Salts (Public Comment and External Review Draft)
- IRIS Toxicological Review of Perfluorohexanesulfonic Acid (PFHxS) and Related Salts (Interagency Science Consultation Draft, 2023)
- External Peer Review Activities for PFHxS Integrated Risk Information System (IRIS) Assessment (Feb 2024)