Perfluorohexanoic Acid (PFHxA)

CASRN 307-24-4

Toxicological Review of Perfluorohexanoic Acid (PFHxA) and Related Salts (Final Report, 2023)


EPA announced the release of the IRIS Toxicological Review Perfluorohexanoic Acid (PFHxA) and Related Salts. The interagency comments on the IRIS Interagency Science Discussion Draft were also released.


EPA has finalized the IRIS Toxicological Review of Perfluorohexanoic Acid (PFHxA) and Related Salts. This assessment addresses the potential cancer and noncancer human health effects from exposure to perfluorohexanoic acid and related salts. EPA’s program and regional offices may use this assessment to inform decisions to protect human health.


U.S. EPA. Toxicological Review of Perfluorohexanoic Acid (PFHxA) and Related Salts (Final Report, 2023). U.S. Environmental Protection Agency, Washington, DC, EPA/635/R-23/027F, 2023.

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Perfluorohexanoic Acid (PFHxA) and its related salts are members of the group of per and polyfluoroalkyl substances (PFAS). Concerns about PFHxA and other PFAS stem from the resistance of these compounds to hydrolysis, photolysis, and biodegradation, which leads to their persistence in the environment. 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.

PFHxA is a breakdown product of other PFAS that are used in stain-resistant fabrics, paper food packaging, and carpets; it is also used for manufacturing photographic film, and it is used as a substitute for longer chain perfluoroalkyl carboxylic acids (PFCAs) in consumer products. PFHxA has been found to accumulate in agricultural crops and has been detected in household dust, soils, food products, and surface, ground, and drinking water.

As such, exposure is possible via inhalation of indoor or outdoor air, ingestion of drinking water and food, and dermal contact with PFHxA-containing products.


Date Description
01-Nov 2019EPA released the Systematic Review Protocol for the PFAS IRIS Assessment (Preliminary Assessment Materials). [Federal Register Notice Nov 8, 2019]
02-Jul 2020EPA released an update to the Systematic Review Protocol for the PFBA, PFHxA, PFHxS, PFNA, and PFDA IRIS Assessments in response to public comments.
03-Aug 2021EPA sent an interagency science consultation PFHxA draft for review and comment.
04-Feb 2022EPA released the draft IRIS Toxicological Review of Perfluorohexanoic Acid (PFHxA) and Related Salts for a 60-day public comment period and external peer review. EPA also released the interagency science consultation documents, comments from reviewers, and EPA's response to major comments. [Federal Register Notice: Feb 2, 2022 ]
05-Aug 2022EPA posted the final peer review report from the contractor on the EPA website.
06-Feb 2023EPA submitted the revised interagency science discussion draft for final Agency and Interagency review.
07-Apr 2023EPA posted the final report IRIS Toxicological Review of Perfluorohexanoic Acid (PFHxA) and Related Salts and released the interagency science discussion draft comments on the IRIS website, and updated key IRIS values for PFHxA in the IRIS database.

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This document has been reviewed in accordance with U.S. Environmental Protection Agency policy and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

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