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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

No toxicity studies in aquatic algae or cyanobacteria are available for sodium borohydride since it rapidly hydrolyzes in water to form sodium borate/boric acid and hydrogen gas with half-lives ranging from seconds to minutes at environmentally relevant pHs. Therefore, aquatic toxicity data for boric acid was used. 

Key value for chemical safety assessment

Additional information

No aquatic toxicity data is available for sodium borohydride since the compound rapidly hydrolyzes in water to form sodium borate/boric acid and hydrogen gas with half-lives ranging from seconds to minutes at environmentally relevant pHs.

Therefore, toxicity data for the toxicologically relevant hydrolysis product boric acid is applied for the safety assessment.

The endpoints included in the dossier under environmental hazard assessment were reported from studies on the ecotoxicity of boron and various compounds, such as boric acid (H3BO3), anhydrous sodium tetraborate (Na2B4O7), and hydrated sodium tetraborates (Na2B4O7.xH2O). All endpoints were converted to concentrations of elemental boron (B) using the relative molar mass and then converted to NaBH4 for this IUCLID. Although a number of studies were available for exposure to aquatic algae or cyanobacteria, the lowest reliable value was taken from a key study with zebrafish. The NOEC was 5.6 mg B/L which was converted to 17.5 mg NaBH4/L and used for freshwater PNEC derivation.