Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

Acute toxicity to aquatic invertebrates

Acutely, zirconium dioxide was not found to be harmful to aquatic invertebrates, as demonstrated in an OECD 202 guideline study, in which no significant immobilization was observed at an initial nominal loading rate of 100 mg/L.

Similarly, for erbium oxide, no significant immobilisation was observed in a 100% v/v saturated solution of erbium oxide in the test medium.

Toxicity to algae

Studies with zirconium compounds, whether 'water soluble' or insoluble, indicate that the observed growth inhibitory effects can be attributed to phosphate depletion of the test medium. 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 dioxide and the tested zirconium compounds are not considered toxic to algae.

A similar phosphate complexing behaviour is known for rare earth elements such as erbium. Because phosphate complexation in algal growth inhibition tests hampers the generation of meaningful test results, it was decided not to add experimental data on the effect of erbium oxide or other erbium compounds on algal growth to this dossier.

Conclusion on erbium zirconium oxide

It is expected that the substance will have a similar aquatic ecotoxicity profile as the read across substances zirconium dioxide and erbium oxide, more specifically that it is not expected to cause any adverse effects on living organisms in the aquatic environment.