Early consent‑order toxicity tests show diverse ecological effects; rodent studies pending

DEQ presented early results from the toxicity studies required under the Chemours consent order. The consent order required multiple aquatic and rodent toxicity tests for five targeted PFAS; results from three aquatic studies (algae growth inhibition, acute Daphnia, and 7‑day fish survival) are now available and show differing potency and dose‑response patterns among the compounds.

Frannie Nielsen summarized the aquatic results: one compound (PFMOAA) reduced algal growth at high laboratory concentrations; acute Daphnia mobility responses were generally minimal across compounds in definitive tests; several compounds produced fish mortality at intermediate or specific time points rather than following a simple monotonic dose‑response. DEQ noted those patterns were sometimes surprising and recommended further mechanistic or follow‑up testing where irregular dose responses were observed.

DEQ also reported progress on rodent studies: range‑finding and protocol approvals are complete for several immunotoxicity and repeated‑dose tests; at least one rodent immunotoxicity test has finished and the final report is expected soon. DEQ cautioned that aquatic tests alone are insufficient to derive human health reference values; typically rodent outcomes would be used to corroborate human‑health endpoints before applying laboratory bioaccumulation factors to regulatory decisions.

Why it matters: the aquatic tests inform environmental exposures and will support bioaccumulation or bioconcentration factor derivation for ecological risk and water‑to‑fish transfer evaluations. The agency said all final reports will be posted and that the results could underpin additional environmental monitoring and targeted mechanistic studies. DEQ plans additional outreach and follow‑up presentations with more complete datasets and comparisons to environmental concentrations.