Magnesium zirconium oxide

Endpoint summary

Additional information

Magnesium zirconium oxide is not classified for any environmental hazard. Therefore, no chemical safety assessment needs to be performed for this substance. In agreement with Column 2 of REACH Annex IX and X, toxicity testing with terrestrial organisms may be required when the outcome of the chemical safety assessment indicates the need for further investigation for this environmental compartment. However, since no chemical safety assessment needs to be performed, it is not considered necessary to fulfill these endpoint requirements. Moreover, for toxicity to terrestrial plants, in a supporting study (Ferrand et al., 2006), in which tomato and pea seedlings were exposed for 7 days to two different soils contaminated with either an insoluble zirconium compound (Zr(OH)4) or a soluble zirconium compound (zirconium acetate or zirconium dichloride oxide), no adverse effects were observed on plant growth. These findings (which are considered relevant for zirconium dioxide) further support the waiving of terrestrial toxicity tests. On the other hand, magnesium, being an essential and internally regulated element, is not expected to cause any adverse effects either. The read across assumption (i.e. the addition of magnesium oxide to the crystal lattice of zirconium dioxide does not alter the unhazardous character of zirconium dioxide) is considered validated by comparison of data for both zirconium dioxide and magnesium oxide for the basic ecotoxicological endpoints acute toxicity to aquatic invertebrates and toxicity to aquatic algae (Annex VII ecotoxicological endpoints).