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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

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Description of key information

In a valid Daphnia acute immobilization test similar to OECD TG 202, the EC50 of isobutyric acid was determined to be 51.25 mg/L (BASF AG, 1989)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
51.25 mg/L

Additional information

Hydrolysis studies show that isobutyric anhydride added to water rapidly converts to isobutyric acid. Thererfore, isobutyric acid data is being used by read across for most environmental fate and ecotox endpoints.

This endpoint is covered by two studies. One study is a valid 48-h acute Daphnia immobilization test (BASF AG, 1989). The second study (Hüls, 1979) cannot be used for assessment of this endpoint due to critical deviations from requirement of actual test guidelines (test period only 24 h).


BASF AG 1989


Isobutyric acid was tested on the waterflea Daphnia magna in a 48-h acute immobilization test similar to OECD TG 202 under static conditions at concentrations of 0 (water control), 15.625, 31.3, 62.5, 125, 250, and 500 mg/L. Immobilization and other toxic effects were observed 3, 6, 24, and 48 h after initiation of the test.


The 48-h EC50 was determined to be 51.25 mg/L (BASF AG, 1989).