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Short-term toxicity to fish:

One short-term toxicity fish study was available using the read-across substance zirconium dioxide as test substance. In this 96h acute toxicity test, Brachydanio rerio was exposed to ZrO2under static conditions according to the OECD guideline 203. Fish were exposed to control and test chemical at a nominal concentration of 100 mg/L. Mortality/immobilization were monitored daily. No mortality was observed during the test, neither in the control nor in the group exposed to the test item. The 96-h LC50 and NOEC were thus > 100 mg/L.

Short-term toxicity to aquatic invertebrates:

The acute toxicity of zirconium basic carbonate to Daphnia magna was studied under static conditions according to OECD Guideline 202/EU method C2. A saturated solution of zirconium basic carbonate (nominal 100 mg/L) did not induce any immobilisation of Daphnia magna after 48 hours exposure. The EC50 is > 100 mg/L.

Toxicity to aquatic algae and cyanobacteria:

The acute toxicity of zirconium basic carbonate to algae was studied. In this study, the observed growth inhibitory effects were attributed to phosphate depletion. Zirconium forms strong complexes with phosphate and therefore, when in excess, precipitates all phosphate from the test medium. No evidence has been found for direct toxic effects to occur to algae upon exposure to zirconium compounds. The phosphate depletion effect in limited systems such as used during aquatic ecotoxicity tests is not considered environmentally relevant and therefore zirconium basic carbonate and the tested zirconium compounds are not considered toxic to algae.

Toxicity to microorganisms:

No reliable studies were available for this endpoint. Microorganisms in an STP will not be exposed to zirconium basic carbonate, as it will either be removed in the primary settling tank before reaching the microorganisms, or it will not be bioavailable due to complexation. In addition, testing is waived based on the following justification in accordance with REACH Annex VIII, 9.1.4 Column 2: the study does not need to be conducted if the substance is highly insoluble in water.