The San Francisco Regional Water Quality Control Board (SFRWQCB) released updated Environmental Screening Levels (ESLs) dated July 18, 2025. This is the first update to the ESLs since 2019 and notably includes soil and groundwater ESLs for 14 new PFAS chemicals as well as updated soil and groundwater cancer risk ESLs for PFOA and PFOS. The newly updated ESLs for PFOA are even more conservative than the interim soil screening levels released by the SFRWQCB in May 2020, with some having decreased by more than an order of magnitude. Because these chemicals are non-volatile, there are no vapor ESLs for PFAS.
PFAS are persistent, man-made chemicals used in a wide range of industrial and consumer products—from firefighting foam and non-stick cookware to food packaging and stain-resistant fabrics. Linked to cancer, liver damage, and immune system disruption, PFAS have been under intensifying regulatory scrutiny, including several high-profile EPA actions in 2024.
The updated ESLs reflect that trend. For example, the residential cancer risk threshold for PFOA in soil dropped from 0.0038 mg/kg (2020) to 0.000019 mg/kg (2025). Similar reductions appear across the commercial/industrial and construction worker scenarios.
| Exposure Scenario | PFOS (mg/kg) 2020 → 2025 | PFOA (mg/kg) 2020 → 2025 |
|---|---|---|
| Residential | 1.2 E-02 → 1.4 E-02 | 3.8 E-03 → 1.9 E-05 |
| Commercial/Industrial | 5.1 E-02 → 5.8 E-02 | 1.6 E-02 → 7.8 E-05 |
| Construction Worker | 2.9 E-01 → 4.7 E-01 | 9.3 E-02 → 6.4 E-04 |
While a number of groundwater ESLs for other chemicals in the Tier 1 ESLs Table were lower by orders of magnitude, this is based on changes to the aquatic habitat levels – seafood ingestion human health. Similarly, several Tier 1 soil ESLs were lowered by orders of magnitude as well. As always, it is important to look past the Tier 1 ESLs to the media-specific ESL tables to ensure the appropriate screening level is used for each site-specific exposure pathway.
The SFRWQCB continues to stress that ESLs are not regulatory thresholds or automatic triggers for cleanup. As reiterated in the User Guide, exceedance of an ESL does not equate to a finding of risk—it signals that further site-specific evaluation is needed. The User Guide states that “ESLs are specifically not intended to serve as: (a) a standalone, decision-making tool; (b) guidance for the preparation of baseline environmental risk assessments; (c) a rule to determine if a waste is hazardous under State or federal regulations; or (d) a rule to determine when the release of hazardous chemicals must be reported to the overseeing regulatory agency.” The User Guide further clarifies that “[t]he presence of a chemical at concentrations exceeding an ESL does not necessarily indicate adverse effects on human health or the environment, but rather that additional evaluation is warranted.”
Key Takeaways for Practitioners and Developers
- Verify the right standard: Do not rely solely on Tier 1 ESLs. Always verify the correct screening levels for each exposure pathway.
- Update due diligence: Make sure your Phase I Environmental Site Assessments reflect the new ESLs.
- Check ongoing projects: If your site is already under remediation or regulatory oversight, consult your environmental team to verify that the applicable standards have not changed.