Systematic Review Protocol for the Pfas IRIS Assessments


EPA announces the availability of the Systematic Review Protocol for the PFBA, PFHxA, PFHxS, PFNA, and PFDA IRIS Assessments for a 45-day public comment period as announced in a November 8, 2019, Federal Register Notice.


The protocol presents the methods for conducting the systematic reviews and dose-response analyses for development of a draft IRIS assessment for five per- and polyfluoroalkyl substances (PFAS) assessments including: perfluorodecanoic acid (PFDA; CASRN 335-76-2), perfluorononanoic acid (PFNA; CASRN 375-24-4), perfluorohexanoic acid (PFHxA, CASRN 307-24-4), perfluorohexanesulfonate (PFHxS, CASRN 355-46-4), and perfluorobutanoic acid (PFBA, CASRN 375 22 4), and their related salts which are all members of the group per and polyfluoroalkyl substances (PFAS). These five toxicity assessments are being developed according to the scope and methods outlined in this protocol built upon several other PFAS assessments that have already been developed by the EPA. It includes a summary of why these specific PFAS were prioritized for evaluation, description of the objectives and specific aims of the assessments, draft PECO (Populations, Exposures, Comparators, and Outcomes) criteria, and identification of key areas of scientific complexity.


U.S. EPA. Systematic Review Protocol for the Pfas IRIS Assessments. U.S. Environmental Protection Agency, Washington, DC, EPA/635/R-19/050, 2019.


Andrew D. Kraft,  Ph:  202-564-0286,  Email:

James W. Avery,  Ph:  202-564-1494,  Email:

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Date Description
Nov 2019EPA released the Systematic Review Protocol for the PFAS IRIS Assessments (Preliminary Assessment Materials). [Federal Register Notice Nov 8, 2019]


Concluding the public comment period, the IRIS Program will use the comments received and the methods outlined in the protocol for conducting the systematic review to develop 5 individual draft assessments.

Additional Information

In addition to being released on the EPA website, the protocol will be published in the Zenodo data repository (

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