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EC number: 238-694-4
CAS number: 14644-61-2
PNEC values for the aquatic compartment cannot be derived. The available
acute ecotoxicity tests in fish and daphnids show EC50 or LC50 values
which are higher than 100 mg/L (based on added test substance) or > 100
% v/v saturated solution. When zirconium sulfate is dissolved in a
buffered aqueous solution (such as a natural surface water)
precipitation of zirconium as zirconium hydroxide/zirconium dioxide (pH
dependent), zirconium carbonate (pH dependent) and/or zirconium
phosphate will occur. The precipitation of zirconium phosphate in algal
test media seems to result in some growth inhibition due to phosphate
deprivation (i.e., a secondary effect). This was demonstrated in algal
growth inhibition experiments with read across substances. The fact that
in an algal growth inhibition test with zirconium sulfate no measurable
zirconium concentrations > LOQ (20 µg Zr/L) could be detected in any of
the treatments whereas 53% reduction of growth rate was observed in the
100% v/v saturated solution supports the assumption that the observed
effects are not due to primary exposure to bioavailable zirconium, but
rather due to a secondary effect such as phosphate deprivation. This
effect is however not considered environmentally relevant as it may only
occur extremely locally. Overall, in view of the extremely low
bioavailability of zirconium in environmentally relevant media at
environmentally relevant conditions, it can be concluded that zirconium
from zirconium sulfate is not toxic to aquatic organisms.
Similarly, microorganisms in a sewage treatment plant are not expected
to be exposed to zirconium (sulfate), as zirconium will have been
removed from the water column through hydrolysis and carbonate and/or
phosphate complexation before reaching the biological treatment step.
Often a pH increase step is included for metal precipitation as one of
the (first) waste water treatment steps in on-site waste water treatment
plants. If such as step is included the removal efficiency will be 100%.
Moreover, no adverse effects have been observed in an activated sludge
respiration inhibition study. Therefore no PNEC needs to be derived.
As no PNEC aquatic 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 to terrestrial plants, yielding
only unbound NOEC values. Therefore, no PNEC values for soil and
sediment can be derived applying the assessment factor either. Since
zirconium sulfate is not considered hazardous to the environment, no
chemical safety assesment needs to be conducted and therefore no PNECs
need to be derived for these compartments.
No long-term oral or dietary avian toxicity studies are available. A
repeated dose toxicity study in rats (OECD 422 study with zirconium
acetate, another 'water soluble' zirconium compound) 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).
Therefore no PNEC oral can be derived. This route is considered not
relevant anyway as it can be reasonably assumed that zirconium will not
bioaccumulate in the food chain.
The substance does not need to be classified for environmental hazards,
based on the available information for zirconium 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 or upon exposure to a 100% v/v saturated solution. Only for
algae, growth inhibition was observed at this limit test concentration
for zirconium sulfate as well as 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.
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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