On April 8, 2021, the US Environmental Protection Agency (US EPA)announced the publication of an updated version of its risk assessment for perfluorobutane sulfonic acid (PFBS; CAS 375-73-5), which sets specific limits for safe long-term (chronic) as well as shorter, sub-chronic exposures. 

Since the inauguration of the new US administration, many US EPA decisions made under the previous one have been under review. The PFBS risk assessment released in January 2021 was one such case that was retracted and re-released again recently after passing the necessary steps and going through internal and external reviews.  

The previous assessment had been criticized widely for including a range of levels for PFBS that would enable industry or state officials to choose higher levels for safety standards. This issue was addressed in the latest version of the assessment by setting specific reference dose values of 0.0003 mg/kg of body weight (bw)/day for safe chronic exposure to PFBS as well as a limit for shorter, sub-chronic exposures of 0.001 mg/kg bw/day. 

The aim of determining single values was to enable public entities to determine whether actions are required to protect the public from harmful exposures. Senior scientist Jennifer Orme-Zavaleta, Assistant Administrator for the Office of Research and Development at the US EPA, commented:“This PFBS assessment reflects the best available science, involved extensive federal, state, and public engagement, and is critical to EPA efforts to help communities impacted by PFAS.”  

PFBS is a per- and polyfluoroalkyl substance (PFAS) applied in food contact materials such as silicones and printing inks (see the FCCdbdatabase), as well as a replacement for perfluorooctanoic acid (PFOA; CAS 335-67-1) and perfluorooctanesulfonic acid (PFOS; CAS 1763-23-1). Like multiple other PFAS, PFBS has been linked to adverse health effects in animal exposure studies, for example, on the thyroid, reproductive organs, fetal development, and kidney function (see the background page on PFAS). In January 2020, the European Chemicals Agency (ECHA)also recognized PFBS as a substance of very high concern (SVHC) (FPF reported) and added it to its Candidate List (FPF reported).   

Read More 

US EPA (April 8, 2021). “EPA Releases Updated PFBS Toxicity Assessment After Rigorous Scientific Review. 

US EPA (April 8, 2021). “Human Health Toxicity Values for Perfluorobutane Sulfonic Acid and Related Compound Potassium Perfluorobutane Sulfonate.”  

US EPA (January 2021). “Human Health Toxicity Values for Perfluorobutane Sulfonic Acid (CASRN 375-73-5) and Related Compound Potassium Perfluorobutane Sulfonate (CASRN 29420-49-3).” (pdf)