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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Hydrolysis

The hydrolysis study cannot be performed as the substance is highly insoluble in water (REACH Annex VIII, 9.2.2.1 column 2). In water, ZrO2 remains an insoluble mass and due to the density it will settle. A very small amount could hydrate and form Zr(OH)4, and only very low amounts will dissolve. The water solubility constant (log Ks,0) varies between -64 to -57 for crystalline monoclinic ZrO2 and between -60 to -52 for amorphous Zr(OH)4 (from: E. Ferrand, Doctorat Universite Paris VI - Pierre et Marie Curie, 2005, Etude de la spéciation en solution, de la rétention dans les sols et du tranfert sol-plantte du zirconium). From this solubility data, Adair et al. (1997) derived theoretical solubilities as a function of pH (see attachment). The predominant species in solution are Zr(OH)4 and Zr(OH)5 - at environmentally relevant pH. At pH values below 5, the predominant species in solution are Zr(OH)3 +, Zr(OH)22 + and ZrOH3 + (Blumenthal WR, 1958, The Chemical Behaviour of Zirconium. Van Nostrand, New York)

Biodegradation

Due to its inorganic nature, biodegradation studies can be waived (REACH Annex VII, 9.2.1.1 column 2).

Bioaccumulation

Due to its extremely low water solubility, the substance will not reach high concentrations in the water, so bioaccumulation in aquatic organisms can be regarded as negligible. Furthermore, due to complexation to organic matter, zirconium dioxide will become unavailable both for aquatic and sediment-dwelling organisms. Based on experimental data available for algae and cyanobacteria (read across from zirconium dichloride oxide, a 'water soluble' zirconium compound), zirconium has no potential to bioconcentrate/bioaccumulate in the aquatic foodchain. Experimental data for terrestrial plants (experiments conducted with zirconium dichloride oxide, zirconium acetate, and zirconium hydroxide, i.e., two 'water soluble' and one 'insoluble' zirconium compound) confirm that neither for the terrestrial foodchain there is a concern for bioaccumulation.

Transport and distribution

Adsorption of zirconium compounds (as such) to particles of suspended matter, sediment, or soil, is not expected to occur. It is rather the zirconium cation (or potentially other cationic zirconium species) that will adsorb to particulate matter. Therefore, the assessment of the potential for adsorption and the derivation of adsorption coefficients is element-based (not substance-based). Based on the derived Kp values, zirconium can be concluded to strongly adsorb to particulate matter. Therefore, its environmental distribution will be mainly to sediment and soil, depending on the emission pathway under consideration. For adsorption to occur however, zirconium has to end up in the aqueous phase of the environmental compartment under consideration (water column, or pore water in sediment/soil).