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Ecotoxicological information

Long-term toxicity to aquatic invertebrates

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Link to relevant study record(s)

Description of key information

Reliable studies on the long-term toxicity to aquatic invertebrates are not available for sodium dichromate. In one unreliable (Klimisch 3) with sodium dichromate, the lowest 48 h EC50 of 0.0005 mg Cr(VI) was derived for the reproduction of Daphnia magna. The substance sodium dichromate consists of sodium cations and dichromate anions (Cr2O7(2 -)). Based on the solubility of sodium dichromate in water, a complete dissociation resulting in sodium cations and chromate anions may be assumed under environmental conditions.Therefore, the fate and toxicity of sodium dichromate in the environment is most accurately evaluated by assessing the fate and toxicity of its ecotoxicologically relevant moiety, i.e. the chromate anion, and read-across to data available for other (soluble) chromate substances is applied.

Please refer to the respective endpoint summary for soluble chromium (VI) substances for further information.

Key value for chemical safety assessment

Additional information

One unreliable (Klimisch 3 study) is available for sodium dichromate: First-instar (<24 h) daphnids of three species (Daphnia magna, Daphnia pulex, Ceriodaphnia reticulata) were exposed to sodium dichromate in a semi-static chronic toxicity test for 14 days (D. magna, D. pulex) and 7 days (C. reticulata), respectively (Elnabarawy et al. 1986). Although the test duration for D. magna was reduced, validity criteria of 3 broods produced, control survival >80% and production of ≥ 60 young per adult female could be fulfilled. A NOEC of 0.0005 mg Cr/L and 0.005 mg Cr/L (nominal) were derived for the reproduction and mortality of D. magna, respectively. For D. pulex, no significant effects on reproduction and survival were observed, although the survival was reduced by 50% at 0.05 mg Cr/L. The validity was not fulfilled for D. pulex, since only 53 young were produced per female during the duration of the test. For C. reticulata, effects on reproduction were observed at the lowest test concentration, while no effects on adult mortality were determined. It is thus not clear how the quoted 7-day LC50 of 17.4 μg/l was derived in the publication.