EPA publishes risk assessment for PFBA, new IRIS Handbook
The U.S. Environmental Protection Agency (EPA) has launched two important documents for its Integrated Risk Information System (IRIS) Program: The Office of Research and Development Staff Handbook for Developing IRIS assessments (IRIS Handbook) and the final IRIS Toxicological Review of Perfluorobutanoic Acid (PFBA) and Related Salts.
EPA’s IRIS program identifies the health hazards of chemicals found in the environment, acting as an important source of toxicity information for both EPA and health organizations.
Final IRIS Toxicological Review
The IRIS Program released its final IRIS assessment of Perfluorobutanoic Acid (PFBA) and Related Salts. PFBA is a breakdown product of other per- and polyfluoroalkyl substances (PFAS) that have been used in stain-resistant fabrics, paper food packaging, carpets, and consumer products; it has also been used for manufacturing photographic film.
The assessment reviews the evidence on the potential noncancer and cancer human health effects resulting from exposure to PFBA. It can be used to support a wide variety of decision-making needs across EPA’s program offices and regions, and state agencies.
Regarding PFBA’s potential cancer effects, the final assessment concludes that there is “inadequate information to assess carcinogenic potential.”
The final assessment found that sufficient oral exposure to PFBA likely causes thyroid, liver, and developmental effects. The final assessment also includes a noncancer estimate of the amount of PFBA that one can ingest every day that is likely to be without harmful effects.
IRIS assessments are only part of a risk assessment. The scientific conclusions regarding hazard identification and dose response from IRIS assessments are typically combined with other scientific information, including information on human exposure, to inform decisions.
Since 2019, IRIS has developed assessments for four PFAS and their associated product — in addition to PFBA, these include Perfluorodecanoic Acid (PFDA), Perfluorononanoic Acid (PFNA), Perfluorohexanoic Acid (PFHxA), and Perfluorohexanesulfonic Acid (PFHxS). In November 2019, the agency opened a public comment period for a draft Systemic Review Protocol of the substances. In October 2021, EPA announced a public comment period on a list of candidates for the IRIS PFAS review panel, which would review the draft Toxicological Reviews of the substances.
The IRIS Handbook
The IRIS Handbook provides procedures for staff developing IRIS assessments, including how to apply systematic review approaches. Systematic review uses prespecified scientific methods to identify, select, assess, and synthesize the findings of similar, but separate, studies. In IRIS assessments, such studies are used to identify human health hazards associated with exposure to chemicals found in the environment and derive toxicity values for health effects resulting from exposure.
EPA says that the procedures set forth in the handbook will apply to newly initiated IRIS assessments moving forward; however, many elements of the handbook have already been incorporated in recently finalized assessments and assessments that are currently in progress. The IRIS Handbook does not supersede existing EPA guidelines and does not serve as direction for other EPA programs.
The Handbook will be updated as needed based on method advancements and experience gained through its application to a broader spectrum of assessments to ensure consistent application of best practices in future IRIS assessments.
“EPA is committed to developing IRIS assessments using consistent, transparent, and scientifically rigorous methods,” said Chris Frey, Assistant Administrator for EPA’s Office of Research and Development. “I am very proud of the scientists who have worked hard to produce a rigorous Handbook at the leading edge of assessment science, and of those scientists who have finalized the PFBA assessment, which will help EPA continue our important work to address PFAS.”