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In contact with moisture/water, Zirconium metal is directly oxidised and a relatively stable passivation layer of ZrO2 is formed at the surface. As ZrO2 is very poorly soluble (0.055 mg/L), the behaviour of Zr in the terrestrial compartment is driven by the solubilisation, complexation and adsorption of ZrO2. Therefore, as for other Zirconium compounds, the relevant substances for read-across purpose that enables to characterize the effect of zirconium towards terrestrial organisms is ZrO2 and any other Zirconium compounds leading to the formation of ZrO2.

No information is available from the literature on toxicity of Zr or Zr compounds to terrestrial organisms.

Concerning the effect on plant, the study available displayed no adverse effect on tomato and pea seedlings (ca. 21 days old) exposed for 7 days to two different soils contaminated with either a soluble Zr compound (ZrOCl2 or Zr acetate) or an insoluble Zr compound (Zr(OH)4). In none of the experiments adverse effects were observed on root or shoot fresh weight of the plants. Unbound NOEC values were obtained for all experiments. The highest unbound NOEC was >= 703.4 mg Zr/kg dw for the acidic soil (417.4 mg Zr/kg background) and the lowest unbound NOEC was >= 450 mg Zr/kg dw for the calcareous soil (164 mg Zr/kg background), both soils amended with 286 mg Zr/kg Zr(OH)4.

Concerning the toxicity to birds, no likely exposure is expected and this endpoint has been waived.

In conclusion, considering all this information and the exposure assessment presented in the CSR that reveals very little likelihood of exposure of the terrestrial compartment (little deposition and no sludge application to agricultural land) no testing proposal is made for terrestrial toxicity of Zr.

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