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EC number: 264-885-7
CAS number: 64417-98-7
No aquatic PNEC values were derived for yttrium zirconium oxide. No
adverse effects were observed in the available toxicity studies (fish
and aquatic invertebrates) with zirconium dioxide and yttrium oxide at
the limit test concentrations. Algal growth inhibition tests with other
zirconium compounds revealed adverse effects on growth which were
however concurrent with phosphate depletion. Phosphate complexation by
both zirconium and rare earth elements represents a technical difficulty
in algal growth inhibition tests which cannot be overcome. Either the
zirconium/rare earth or the phosphate will be depleted from the test
medium, depending on which of both is in excess of the other. Therefore,
no meaningful results can be obtained in algal growth inhibitions tests
with zirconium or rare earth compounds. The phosphate deprivation effect
is a secondary effect and is not considered environmentally relevant
since it may only occur at a very small local scale, such as at point
discharges. Taking all this in account, yttrium zirconium oxide can be
considered non-hazardous to aquatic organisms, as is the case for
zirconium dioxide and yttrium oxide too.
Because the substance does not need to be classified for any
environmental hazard, no chemical safety assessment needs to be
conducted. Therefore, and taking into account the results of the aquatic
toxicity tests included in this dossier, it is not considered necessary
to perform toxicity tests with sediment or terrestrial organisms. As for
aquatic organisms, the substance is not considered to be hazardous to
sediment or terrestrial organisms. This is supported by the results of a
short-term study (using zirconium hydroxide, zirconium acetate, and
zirconium dichloride oxide) in terrestrial plants, which did not reveal
any adverse effects up to the highest doses tested. Therefore no PNEC
values were determined for sediment and terrestrial organisms either.
Finally, no PNEC value was determined for secondary poisoning since the
available mammalian studies indicate that zirconium dioxide nor yttrium
oxide is a hazardous substance and because there is no concern for
bioaccumulation or biomagnificiation of zirconium or yttrium in both the
aquatic and terrestrial environment.
As yttrium zirconium oxide has a limited water solubility,
concentrations of yttrium or zirconium which are toxic to aquatic
organisms are anticipated not to be reached. This is supported by
information from acute fish and daphnid tests with zirconium dioxide and
yttrium oxide. These individual substances were not found to cause any
adverse effects in daphnids and fish up to the limit test
concentrations, and are hence not classified for any environmental
hazard. Based on these fish and daphnid tests it is concluded that
yttrium zirconium oxide is not to be classified for environmental
hazards either. Data from algal growth inhibition tests are not
considered for classification purposes since the strong complexation of
zirconium and rare earth elements such as yttrium with phosphates in the
test medium confuses the results of these tests. The adverse effects on
algal growth observed in such tests are due to phosphate deprivation and
are not a direct toxic effect of zirconium or the rare earth itself.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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