Board hears proposed PFAS notification and response level changes; OEHHA recommends 1 μg/L PFHxA NRL

At an informational hearing on Aug. 6, State Water Board staff presented proposed revisions to notification levels and response levels for several PFAS compounds and received an OEHHA recommendation for a new PFHxA notification level.

What staff proposed

- PFOA and PFOS: DDW proposed lowering the notification level (NL) for each compound to 4 nanograms per liter (ng/L) to align with the current U.S. EPA maximum contaminant level (MCL). Staff recommended no change to the existing response levels (RLs) while the federal MCL schedule is implemented.

- PFHxS: staff proposed converting the existing RL of 20 ng/L (single confirmed sample) to a 10 ng/L running annual average. The change would harmonize the metric with other PFAS RLs and mirror the U.S. EPA approach for PFHxS.

- PFHxA: OEHHA recommended a new NL of 1 microgram per liter (1 μg/L = 1 part per billion). Chris Banks, senior toxicologist at OEHHA, summarized the derivation: OEHHA screened the literature, identified a small set of animal studies (Loveless et al., NTP and others), used benchmark‑dose modeling of critical endpoints (nasal cavity degeneration, decreased thyroid hormone), applied a composite uncertainty factor (300) and a 20% relative source contribution to reflect non‑water exposure, and rounded a…