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Short-term toxicity to fish

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Description of key information

In the course of the 96-h limit test with Danio rerio, applying 100 mg/L tantalum pentachloride, no mortality was observed. Therefore, no further testing was carried out. The analytically measured tantalum concentration in solution showed high variability and ranged from below the detection limit of 0.5 µg/L to 32.2 µg/L. This was mainly due to instability in the neutralized medium and agglomeration effects. The chemical analysis revealed a geometric mean of 1.76 µg/L (measured) of the test item in the test media. Hence, the 96-h LL50 (nominal) is > 100 mg/L, the LC50 based on measured concentrations is > 1.76 µg/L.

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Additional information

In the course of a 96-h limit test with Danio rerio according to OECD Guideline 203 (July 1992) applying 100 mg/L tantalum pentachloride under semi-static conditions, no mortality was observed. Therefore, no further testing was carried out. The analytically measured tantalum concentration in solution showed high variability and ranged from below the detection limit of 0.5 µg/L to 32.2 µg/L. This was mainly due to the fact that small changes in pH caused significant changes in the soluble fraction of the test substance. Additionally, tantalum pentachloride precipitated after adjusting the pH and agglomeration reactions and effects of adsorption to vials and analytical instruments contributed to the varying measured tantalum concentrations in solution. Therefore, effect levels are given as nominal loading rates and mean measured concentrations of tantalum. The chemical analysis revealed a geometric mean of 1.76 µg/L (measured) of the test item in the test media. Hence, the 96-h LL50 (nominal) is > 100 mg/L, the LC50 based on measured concentrations is > 1.76 µg/L. This study is classified as acceptable and satisfies the guideline requirement for a fish acute toxicity study.