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Ecotoxicological information

Short-term toxicity to fish

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Description of key information

Key study was performed with ZrO2 on Danio rerio during 96 hours according to OECD guideline 203. Results displayed a LL50 and a NOELR > 100 mg/L of ZrO2. In terms of zirconium element, this correspond to a NOELR (96h) > 190 mgZrCl4/L. 

Key value for chemical safety assessment

LC50 for freshwater fish:
190 mg/L

Additional information

Three studies have been identified for short-term toxicity to fish based on read-across from zirconium compounds. The key study selected is a study performed with zirconium dioxide (ZrO2). Zirconium tetrachloride once in water, dissosciates into HCl and hydrated forms of ZrO2 (The most stable form of zirconium in water). Therefore, the study testing the toxicity of fish with ZrO2 is suitable to characterize the effect of zirconium tetrachloride. This test with a 96 hours exposure of Danio rerio to ZrO2 displayed a LL50 and a NOELR of > 100 mgZrO2/L which corresponds in terms of ZrCl4 a concentration of > 190 mg ZrCl4/L.

The second study identified for fish toxicity, was performed with zirconium tetrachloride. The authors did not neutralized water solution and therefore a pH-induced effect was observed at high concentration due to the degradation of ZrCl4 into HCl. However, the pH-induced effect was inexistent at 20 mgZr/L (pH = 6.0). Therefore LC50 for this study was at least > 51 mg ZrCl4/L.

Unfortunately, the third study performed with zirconium dichloride oxide (ZrOCl2) on Heteropneustes fossilis and Clarius sp. was disregarded because very few information was available for the fish toxicity test. Nevertheless, no effect was observed at a loading rate of 100 mg ZrOCl2/L (i.e 130 mg ZrCl4/L).