On October 7, 2024 the United States Environmental Protection Agency (EPA) published final water quality numerical limits for 10 per- and polyfluoroalkyl substances (PFAS) intended for
the protection of aquatic life. These numerical limits are a combination of water quality criteria and benchmarks that can be used by States and Tribes to develop own regulations under the Clean Water Act (CWA) such as water quality standards and
wastewater discharge permits.
The process of developing PFAS Aquatic Life Criteria (ALCs) began back in 2022, focusing solely on two main substances, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in freshwater. The latest announcement from EPA not only expands
the scope to include marine limits for POFA and PFOS, but also unexpectedly includes Aquatic Life Benchmarks (ALBs) for eight additional PFAS:
- perfluorobutanoic acid (PFBA)
- perfluorohexanoic acid (PFHxA)
- perfluorononanoic acid (PFNA)
- perfluorodecanoic acid (PFDA)
- perfluorobutanesulfonic acid (PFBS)
- perfluorohexanesulfonic acid (PFHxS)
- hexadecafluoro-2-decenoic acid (8:2 FTUCA)
- pentadecafluorodecanoic acid (7:3 FTCA)
Under the CWA, ALCs and ALBs represent the maximum concentrations of pollutants in water and fish/aquatic invertebrate tissues without adverse effects on survival, growth, and reproduction within the whole ecosystem. In general, the aquatic toxicity of
PFAS is relatively low as measured in parts per million vs. parts per trillion for drinking water standards intended for human consumption. Certain
PFAS can persist in the environment and have bioaccumulative properties. Combined, these characteristics make PFAS of concern in aquatic environments.
While ALCs are based on sufficient scientific information on adverse effects, ALBs are less certain due to data gaps, some of which are filled with toxicity approximation and modeling tools. However, both can serve as reference concentrations to gauge
impacts on biota and as the basis for developing State and Tribal water standards for EPA’s concurrence and approval. According to EPA, ALCs and ALBs are not enforceable until adopted as standards.
What Are the New Aquatic Life PFAS Limits?
EPA’s factsheet contains limit summaries as presented in Tables 1-3. Limits are available for short- and long-term (i.e.,
acute and chronic) exposures, bioaccumulation-based scenarios, and freshwater and saltwater ecosystems. Additive toxicity of co-occurring PFAS compounds is not accounted for. That aspect will need to be addressed separately via the application of
established environmental risk assessment procedures when dealing with chemical mixtures. Strongest scientific evidence was available to support freshwater criteria, less so for saltwater, and benchmarks the least. Each limit serves as an independent
line of evidence, and none take precedence.
Table 1. Final Recommended Freshwater Aquatic Life Water Quality Criteria for PFOA/PFOS
| Criteria Component | Acute Water Column (CMC)1
(mg/L) | Chronic Water Column (CCC)2
(mg/L) | Invertebrate Whole-Body
(mg/kg ww3) | Fish Whole-Body
(mg/kg ww3) | Fish Muscle
(mg/kg ww3) |
| PFOA | 3.1 | 0.10 | 1.18 | 6.49 | 0.133 |
| PFOS | 0.071 | 0.00025 | 0.028 | 0.201 | 0.087 |
| Duration | 1-hour average | 4-day average | Instantaneous | Instantaneous | Instantaneous |
| Frequency | Not to be exceeded more than once in 3 years, on average | Not to be exceeded more than once in 3 years, on average | Not to be exceeded | Not to be exceeded | Not to be exceeded |
1Criterion maximum concentration (CMC) - highest water concentration of a substance to which an aquatic community can be exposed to briefly without an unacceptable effect.
2Criterion Continuous Concentration (CCC)- highest water concentration of a substance to which an aquatic community can be exposed to indefinitely without an unacceptable effect.
3wet weight (ww) - total weight of aquatic life tissue, not dried to remove water.
mg/L – milligrams per liter
mg/kg – milligrams per kilogram
Table 2. Acute Saltwater Aquatic Life Benchmarks for PFOA/PFOS
| Chemical | PFOA (mg/L) | PFOS (mg/L) |
| Concentration | 7.0 | 0.55 |
| Duration | 1-hour average |
| Frequency | Not to be exceeded more than once in 3 years on average |
Tabe 3. Acute Freshwater Aquatic Life Benchmarks for PFAS
| Chemical | PFBA
(mg/L) | PFHxA
(mg/L) | PFNA
(mg/L) | PFDA
(mg/L) | PFBS
(mg/L) | PFHxS
(mg/L) | 8:2 FTUCA
(mg/L) | 7:3 FTCA
(mg/L) |
| Magnitude | 5.3 | 4.8 | 0.65 | 0.50 | 5.0 | 0.21 | 0.037 | 0.012 |
| Duration | 1-hour average |
| Frequency | Not to be exceeded more than once in 3 years on average |
New PFAS Limits Compliance
While EPA indicates that by themselves, the criteria and benchmarks are neither regulatory nor legally required, the practicality is that they may find various uses, making them controlling in nature. For example, ambient water quality testing programs, contaminated site assessments, and/or prospective real estate Phase 1/2 evaluations typically screen results against all and any available limits from any publication source. Thus, PFAS ALCs/ALBs may be included in those assessments to provide interpretation of results and perhaps serve as the basis for risk management decisions. Another example may be effluent permitting, where receiving water body parameters shall be met despite the anticipated point source releases.
Curious About How the Latest PFAS News Impacts You? We Can Help
We will continue to monitor PFAS developments and keep you updated. Please be on the lookout for additional articles on this topic. Meanwhile, if you have PFAS-related questions, concerns, or challenges, drop your information into our contact form and we’ll schedule a time to discuss how you can prepare for and manage PFAS-related regulations.
