Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

To assess the potential for bioaccumulation of a substance like erbium zirconium oxide, information on the individual metallic elements should be considered.

The available information on bioaccumulation of zirconium in the aquatic and terrestrial foodchain was studied in algae and higher terrestrial plants respectively, yielding the following conclusions:

- Although no data are available on other aquatic organisms besides algae and cyanobacteria, it can be concluded that zirconium has no potential to bioconcentrate/bioaccumulate in the aquatic foodchain. A rapid uptake of zirconium from the medium was observed as well as a rapid desorption. The BCF values obtained for cyanobacteria and microalgae were very low, the highest value being 0.064 L/kg ww. The available study used zirconium dichloride oxide as test compound, which is a 'water soluble' zirconium compound that however rapidly transforms to zirconium oxide or other non-soluble forms under environmentally relevant conditions.

- Based on a study on the transfer of zirconium from soil to plants, it could further be concluded that there is no potential for bioaccumulation of zirconium in the terrestrial foodchain, as all BSAF values were < 0.1, which is well below 1. In this study both soluble and non-soluble forms were used. The BSAF values were quite similar, but even lower for non-soluble forms than for soluble forms.

Erbium oxide is expected to have a similar extremely low bioaccumulation potential as zirconium oxide based on the similar extremely low water solubility of both compounds as well as the effect of environmentally relevant pH levels on dissolution of erbium and zirconium.

Therefore it can be concluded that there is no concern for bioaccumulation of erbium or zirconium from the use of erbium zirconium oxide.