Zirconium oxide sulphate

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

no hazard identified

STP

Hazard assessment conclusion:

no emission to STP expected

Sediment (freshwater)

Hazard assessment conclusion:

insufficient hazard data available (further information necessary)

Sediment (marine water)

Hazard assessment conclusion:

insufficient hazard data available (further information necessary)

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

insufficient hazard data available (further information necessary)

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

PNEC values calculated using assessment factors cannot be derived. In the available acute ecotoxicity tests in fish and daphnids (performed with similar water insoluble zirconium substances) no adverse effects were observed up to and including the maximum loading rate of 100 mg/L. In view of the extremely low water solubility of zirconium basic sulfate, concentrations that would be toxic for aquatic organisms will never be reached. In the available algal growth inhibition studies (also performed with similar water insoluble zirconium substances), adverse effects on growth were observed at the maximum loading rate of 100 mg/L, however, the observed effects were concurrent with phosphate depletion from the test medium, due to complexation with zirconium. This is hence a secondary effect, which is not considered relevant under environmentally realistic conditions.

Microorganisms in a sewage treatment plant are not expected to be exposed to zirconium from zirconium basic sulfate, as zirconium basic sulfate is insoluble. Therefore, exposure-based waiving of the endpoint is allowed and no PNEC needs to be derived.

As no PNECaquatic could be derived, no PNEC values for soil and sediment can be derived either by using the equilibrium partitioning method. No toxicity data are available for sediment or soil organisms, except for a short-term toxicity study with terrestrial plants, yielding only unbound NOEC values for both an insoluble and two 'water soluble' zirconium compounds. Therefore, no PNEC values for soil and sediment can be derived applying the assessment factor method either. Since zirconium basic sulfate is not considered hazardous to the environment, no chemical safety assessment needs to be conducted and therefore no PNECs need to be derived for these compartments.

No long-term toxicity studies to birds are available. A PNECsecondary poisoning should not be derived because zirconium does not bioaccumulate in the foodchain and because zirconium basic sulfate is not expected to give rise to bioavailable zirconium in the environment. Furthermore, a repeated dose toxicity study in rats (OECD 422) performed with the 'water soluble' zirconium substance zirconium acetate, did not observe any significant adverse effects up to and including the highest tested dose (NOAEL >= 1000 mg/kg bw/day, based on anhydrous test compound). This study indicates that even 'water soluble' zirconium compounds are not hazardous to organisms at higher levels in the foodchain.

Conclusion on classification

The substance does not need to be classified for environmental hazards, based on the available information for zirconium basic sulfate, used in combination with information from read across substances. In none of the studies used to cover the aquatic toxicity endpoints, adverse effects have been observed up to and including the limit test concentration of 100 mg/L. Only for algae, growth inhibition was observed at this limit test concentration for two read across substances, however, the observed inhibition was concurrent with phosphate depletion from the test medium (through heavy complexation with zirconium), and was hence considered a phosphate deprivation effect, which is not considered relevant at a normal environmental scale. Since there were no signs of primary toxicity, the effect in algae was not considered relevant for hazard assessment or classification purposes.