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Sediment toxicity

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Reference
Endpoint:
sediment toxicity: long-term
Data waiving:
other justification
Justification for data waiving:
other:

Description of key information

Taking into account (i) the rapid dissociation of sodium dithionite and decomposition of dithionites upon dissolution in environmental solutions, including sediment porewater, and respective participation in the natural sodium and sulfur cycle, (ii) ubiquitousness of sodium and inorganic sulfur substances in sediment, (iii) essentiality of sodium and sulfur, and (iv) the lack of a potential for bioaccumulation and toxicity to aquatic organisms, the hazard potential of sodium dithionite in sediment can be expected to be low.

Key value for chemical safety assessment

Additional information

Due to the instability of sodiumdithionite under environmental conditions (decomposition to sulfite and sulfate) and its physicochemical properties which make adsorption to sediments unlikely, the derivation of a PNEC for the sediment compartment is not feasible/appropriate:

-      due to rapid oxidation of sodium dithionite, no relevant test design and toxicity data can be generated

-      due to the lack of a relevant adsorption coefficient for dithionites to sediment, the equilibrium partitioning method for deriving a PNECsediment is not applicable

-      taking into account the industrial use, exposure pathways and environmental fate of sodium dithionite, long-term exposure of sediment organisms to this substance can be excluded.

Consequently, there is no need to derive a PNECsediment for sodium dithionite.