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Ecotoxicological information

Toxicity to terrestrial plants

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In the study of Ferrand et al. (2006) no adverse effects were observed when exposing tomato and pea seedlings either to soluble zirconium compounds (zirconium dichloride oxide or zirconium acetate) or insoluble zirconium compounds (zirconium hydroxide) added to soil. Only unbound NOEC values were obtained. Since the experiments only lasted for 7 days, the long-term toxicity endpoint (Annex X) is not covered. However, since there is no concern for terrestrial toxicity at the moment, the Annex X endpoint can be waived.

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A single study was identified containing relevant and reliable information on toxicity of zirconium substances to terrestrial plants. In this study (Ferrand et al., 2006), tomato and pea seedlings (ca. 21 days old) were exposed for 7 days to two different soils contaminated with either a soluble zirconium compound (ZrOCl2 or zirconium acetate) or an insoluble zirconium 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 lowest unbound NOEC was >= 264 mg Zr/kg dw for the calcareous soil (164 mg Zr/kg background) amended with 100 mg Zr/kg ZrOCl2 or Zr acetate. The highest unbound NOEC was >= 703.4 mg Zr/kg dw for the acidic soil (417.4 mg Zr/kg background) amended with 286 mg Zr/kg Zr(OH)4. Since zirconium hydroxide is also an insoluble zirconium compound, the latter value is most likely most relevant for zirconium basic sulfate.

Since the above experiments only lasted for 7 days, the long-term toxicity endpoint (Annex X) is not covered. However, since there is no concern for terrestrial toxicity at the moment, the Annex X endpoint can be waived.