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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

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Description of key information

The value of 98.3 mg Na2S2O4/L is put forward for the environmental classification of sodium dithionite.	

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
98.3 mg/L

Additional information

The reliable key study (BASF, 1989) on the acute toxicity of sodium dithionite used the cladoceran Daphnia magna as test species. The reported nominal 48h-EC50 was 98.3 mg test material/L, which corresponds to 36.2 mg S/L or 90.3 mg SO32 -/L. A drop in pH and oxygen levels of the test medium was noted with increasing levels of sodium dithionite, but levels were still acceptable at EC50-level, indicating that observed toxicity was not only related to physicochemical conditions of the test medium.