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Short-term toxicity to aquatic invertebrates

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The rate and extent to which chromium (III) oxide produces soluble (bio)available ionic and other chromium-bearing species in environmental media is limited. Further, the poor solubility of chromium (III) oxide is expected to determine its behaviour and fate in the environment, and subsequently its potential for ecotoxicity. Proprietary studies are not available for chromium (III) oxide. However, the fate and toxicity of chromium (III) oxide in the environment is evaluated by assessing the fate of its ecotoxicologically relevant moiety, the chromium (III) ion, and read-across to data available for other chromium (III) substances is applied.

In accordance with ECHA’s Guidance on IR & CSA, Appendix R.7.13-2 (2008), the poorly soluble substance chromium (III) oxide is evaluated by comparing the dissolved chromium (III) ion level resulting from the T/Dp at a loading rate of 1 mg/L after 7 d with the lowest acute effect concentration as determined for the (soluble) chromium (III) ion.The lowest reliable acute effect concentration determined for the (soluble) chromium (III) ion is a 48 h LC50 of 3.71 mg Cr(III)/L observed in an acute toxicity test on the effects of chromium (III) chloride on Ceriodaphnia dubia neonates (Baral et al., 2005). Dissolved chromium concentrations of <0.01 µg/L in the T/Dp after 7 days at pH 6 (i.e. the pH that maximizes the dissolution) are significantly lower than the lowest reliable acute effect concentration derived for aquatic invertebrates (i.e. LC50 of 3.71 mg Cr(III)/L). Hence, chromium (III) oxide is not sufficiently soluble in environmental media to cause acute toxicity to aquatic invertebrates at the level of the lowest acute effect concentration (expressed as the LC50).

For further information on the applied read-across approach and the evaluation of the poorly soluble substance chromium (III) oxide, please refer to the section "Cr2O3_Aquatic toxicity".

Based on the poor solubility of chromium (III) oxide in environmental media, acute toxicity to aquatic invertebrates is not expected.

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