Final Recommended Aquatic Life Criteria and Benchmarks for Select PFAS

SUPPLEMENTARY INFORMATION:

I. How can I get copies of these documents and other related information?

The EPA has established a first docket for the “Final Recommended Freshwater Aquatic Life Ambient Water Quality Criteria and Saltwater Acute Benchmarks for Perfluorooctanoic Acid (PFOA)” under Docket ID No. EPA-HQ-OW-2022-0365 and a second docket for the “Final Recommended Freshwater Aquatic Life Ambient Water Quality Criteria and Saltwater Acute Benchmarks for Perfluorooctane Sulfonate (PFOS)” under Docket ID No. EPA-HQ-OW-2022-0366. Publicly available docket materials are available either electronically through www.regulations.gov or in hard copy at the EPA Docket Center, WJC West Building, Room 3334, 1301 Constitution Ave. NW, Washington, DC. The Docket Center's hours of operations are 8:30 a.m.-4:30 p.m., Monday through Friday (except Federal holidays). For further information on the EPA Docket Center services and the current status, see : https://www.epa.gov/dockets.

The “Final Recommended Freshwater Aquatic Life Ambient Water Quality Criteria and Saltwater Acute Benchmarks for Perfluorooctanoic Acid (PFOA)” document can be accessed on the EPA's website through the following link: https://www.epa.gov/system/files/documents/2024-09/pfoa-report-2024.pdf. The “Final Recommended Freshwater Aquatic Life Ambient Water Quality Criteria and Saltwater Acute Benchmarks for Perfluorooctane Sulfonate (PFOS)” document can be accessed on the EPA's website through the following link: https://www.epa.gov/system/files/documents/2024-09/pfos-report-2024.pdf. The “Final Acute Freshwater Aquatic Life Benchmarks for Eight Data-Limited PFAS: PFBA, PFHxA, PFNA, PFDA, PFBS, PFHxS, 8:2 FTUCA, and 7:3 FTCA” document can be accessed on the EPA's website through the following link: https://www.epa.gov/system/files/documents/2024-09/pfas-report-2024.pdf.

II. What are PFAS, including PFOA and PFOS?

Per- and polyfluoroalkyl substances (PFAS) are human-made organic chemical compounds composed of a carbon chain bound to multiple fluorine atoms. PFAS have been manufactured and used by a broad range of industries since the 1940s, and there are estimated to be thousands of PFAS present in the global marketplace that are used in a range of commercial and industrial products. PFOA and PFOS are two of the most widely used and studied chemicals in the PFAS group. PFAS are not naturally occurring and have no biologically important functions or beneficial properties to aquatic life. PFAS, including PFOA and PFOS, can persist in the environment and have been detected in U.S. rivers, lakes, and streams. At elevated concentrations, PFAS can be toxic to fish and other aquatic species.

III. What are CWA national ambient water quality criteria and benchmarks developed by the EPA?

CWA section 304(a) directs the EPA to develop and publish water quality criteria that reflect the latest scientific knowledge. The EPA develops national recommended ambient water quality criteria for the protection of aquatic life based on the highest numeric concentrations of pollutants, with specific recommendations on the duration and frequency of those concentrations, that are protective of aquatic ecosystems as a whole. The EPA's section 304(a)(1) criteria recommendations generally follow the Guidelines methods ( Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Organisms and Their Uses), which recommend toxicity data for a minimum of eight families of aquatic animals be used in developing aquatic life criteria to ensure criteria will protect aquatic ecosystems as a whole. Water quality criteria are based solely on data and scientific judgments about the relationship between pollutant concentrations and potential environmental effects. The EPA's recommended water quality criteria are not regulatory, nor do they automatically become part of a State's water quality standards. States must adopt into their standards water quality criteria that protect the designated uses of their water bodies. States can establish water quality criteria based on the EPA's recommended criteria, modify recommended criteria to reflect site-specific conditions, or develop proposed standards using on other scientifically defensible methods. A State's or Tribe's water quality criteria are not legally effective under the Clean Water Act until they have been adopted into a State's or Tribe's water quality standards and are approved by the EPA.

Aquatic life benchmarks, developed under section 304(a)(2) of the CWA, are informational values that the EPA generates when there are limited high quality toxicity data available and data gaps exist for several aquatic organism families. The EPA develops aquatic life benchmarks to provide information that States and Tribes may consider in their water quality protection programs. In developing aquatic life benchmarks, data gaps may be filled using new approach methods (NAMs), such as computer-based toxicity estimation tools ( e.g., EPA's Web-ICE; Version 3.3; https://www.epa.gov/webice/ ) or other new approach methods intended to reduce reliance on additional animal testing ( https://www.epa.gov/chemical-research/epa-new-approach-methods-work-plan-reducing-use-vertebrate-animals-chemical ), including the use of read-across estimates based on other chemicals with similar structures. The EPA's aquatic life benchmark values are not regulatory, nor do they automatically become part of a State's water quality standards.

IV. What are the EPA's recommended criteria for PFOA and PFOS in freshwater for the protection of aquatic life?

The EPA has developed separate PFOA and PFOS criteria to protect aquatic life from the effects of these individual chemicals. The EPA developed these final recommended aquatic life ambient water quality criteria following the general approach outlined in the EPA's Guidelines. The EPA developed the final PFOA and PFOS recommended criteria to protect aquatic life designated uses established for freshwaters. The final criteria documents contain acute and chronic water column criteria for freshwaters (see Table 1 of this document). Acute criteria protect aquatic species from short-term exposures to high pollutant concentrations while chronic criteria protect aquatic species from long-term and repeated pollutant exposures. The final criteria also contain chronic criteria expressed as PFOA and PFOS concentrations in fish muscle tissue, fish whole-body tissue, and in invertebrate tissue (see Table 1 of this document). Many States and Tribes measure PFAS in fish tissues and these tissue-based criteria values allow States and Tribes to assess the health of fish and invertebrates in their freshwaters. The chronic freshwater and chronic fish/invertebrate tissue-based criteria for both chemicals are intended to be independently applicable and no one criterion takes primacy.

The PFOA and PFOS criteria establish maximum concentrations ( i.e., magnitude component), averaged over a given time period ( i.e., duration component), that if not exceeded more than the allowable number of times during a specified time period ( i.e., frequency component), are expected to protect aquatic ecosystems as a whole. The duration components of criteria are set to be substantially shorter than the length of toxicity tests used to derive the criteria magnitude and restrict allowable fluctuations in pollutant concentrations over time. The frequency components of aquatic life criteria ensure aquatic communities have adequate time to recover following a criteria exceedance event. The EPA's final recommended PFOA and PFOS criteria magnitudes combined with the associated duration and frequency components are expected to protect fish and other aquatic species in freshwaters (see Table 1).