Zirconium oxide (ZrO2), erbium-doped

Short-term toxicity to aquatic invertebrates

Description of key information

1. Information on zirconium dioxide (CAS# 1314-23-4)
The 48-h NOEC and 48-h EC50 were >= 100 mg/L and > 100 mg/L, respectively, as no significant immobilization was observed at the initial nominal loading rate of 100 mg/L.
2. Information on erbium oxide (CAS# 12061-16-4)
The 48-h NOEC and 48-h EC50 were >= 100 % v/v saturated solution and > 100% v/v saturated solution, respectively, as no significant immobilization was observed in a saturated solution of erbium oxide in test medium.
3. Conclusion on erbium zirconium oxide
It is expected that the substance will have a similar ecotoxicity profile as the read across substances zirconium dioxide and erbium oxide.

Additional information

1. Information on zirconium dioxide (CAS# 1314-23-4)

In a study from Bazin (1994), the acute toxicity of the read across substance zirconium dioxide to Daphnia magna was studied under static conditions according to EU method C2. Daphnids were exposed to control and test chemical at an initial loading rate of 100 mg/L for 48 hours. Mortality and immobilization were observed after 24 and 48 hours. No significant immobilization was observed at the loading rate of 100 mg/L. The 48-h NOEC and 48-h EC50 were thus superior to this value.

2. Information on erbium oxide (CAS# 12061-16-4)

In a study from Harris (2013), the acute toxicity of the read across substance erbium oxide to Daphnia magna was assessed in a study conducted in accordance with the standardised guidelines OECD 202 and EU Method C.2 under GLP conditions. In a limit test, twenty daphnids (4 replicates of 5 animals) were exposed to an aqueous solution of the test material at a concentration of 100 % v/v saturated solution for 48 hours under static test conditions. Immobilisation and any adverse reactions to exposure were recorded after 24 and 48 hours. The study showed that there were no toxic effects at saturation as no immobilisation was seen. Therefore the 48 hour EC50 based on nominal test concentrations was greater than 100 % v/v saturated solution. The No Observed Effect Concentration was ≥100 % v/v saturated solution.

3. Conclusion on erbium zirconium oxide

Both zirconium dioxide and erbium oxide were demonstrated not to cause any immobilisation in acute daphnid toxicity studies at the limit test dose (initial loading rate of 100 mg/L or saturated solution prepared using this loading rate). Therefore, it can be concluded that erbium zirconium oxide will not be harmful to daphnids either.