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EC number: 939-967-7
CAS number: -
No data are available on repeated dose toxicity of erbium zirconium oxide. According to the read across approach (see IUCLID Section 13), the addition of erbium oxide to the zirconium dioxide crystal lattice is not expected to change its toxicological properties. Therefore, it is assumed that erbium zirconium oxide has a similar toxicological profile as zirconium dioxide. Consequently, the substance is not expected to cause any adverse effects after repeated exposure. The following data on repeated dose toxicity are included in this dossier:
Repeated dose toxicity: oral
No reliable information is available for zirconium dioxide either. Therefore, the read across data used in the zirconium dioxide dossier are used here too to cover the endpoint. Thus, a study with zirconium acetate (a 'water soluble' zirconium compound) and a study with zirconium basic carbonate (an insoluble zirconium compound such as zirconium dioxide) are used in a weight of evidence approach and support each other in the fact that no oral toxicity was observed after repeated oral exposure. The read across justification is included in Section 13 of IUCLID.
No effects were reported after oral administration to rats during 17 weeks of zirconium hydrated basic carbonate in the form of a moist paste containing 20.9% zirconium dioxide in a reliable study (Klimisch 2) (Harrison et al., 1951). The total intake of zirconium dioxide during the test period was 0, 0.9, 9 and 103.5 g. The equivalent NOAEL for zirconium dioxide was >= 3150-7080 mg/kg bw/day. A similar study was performed on kittens, but the reported information from that study is limited and thus is considered as supporting information.
The systemic toxic effects of zirconium acetate solution (containing 40.7% of the active ingredient zirconium acetate) after oral repeated exposure, as well as any toxic effects on reproduction and development were investigated in Sprague Dawley rats up to early lactation (day 4 post partum). The study (Rossiello, 2013) was performed according to OECD guideline 422 (GLP).
Three groups of 10 males and 10 females each received the test item, by oral gavage, at 100, 300 and 1000 mg/kg bw/day, expressed as zirconium acetate (anhydrous form). A similar constituted control group received the vehicle alone during the treatment period. The test item was diluted in purified water (vehicle) at concentrations of 10, 30 and 100 mg of zirconium acetate/mL. Chemical analyses of the formulated test item were performed during the study and the overall results were within the limits of acceptance. The overall dosing period was 32 days for males, which included 2 weeks before pairing and continuously thereafter up to the day before necropsy and up to 50 days for females including 2 weeks before pairing and thereafter during pairing, gestation and lactation periods until day 3 post partum.
The animals were followed for daily clinical signs, weekly body weight, food consumption, neurotoxicity assessment, oestrous cycle, mating performance, clinical pathology evaluation including haematology and clinical chemistry and offspring delivery. A detailed macroscopic examination, organ weights and histopathology including the spermatogenic cycle were performed.
No treatment-related findings were observed either during the in vivo phase or at post mortem examination. Microscopically, a treatment-related finding was seen in males receiving 300 and 1000 mg/kg bw/day consisting of minimal focal vacuolation of squamous epithelium (limiting ridge) of non-glandular region of the stomach. This change may be attributed to a local irritant effect of the compound administered by oral gavage and since humans do not have a forestomach or structure analogous to the forestomach, it is not considered of toxicological relevance.
No systemic adverse effects were therefore reported. On the basis of these results, the NOAEL (No Observed Adverse Effect Level) for systemic toxicity after repeated oral exposure was considered to be >= 1000 mg of zirconium acetate/kg bw/day for both males and females.
Taking into account the concept of the more water soluble is the substance the higher is its potential for systemic bioavailability, it could be concluded that systemic toxicity after repeated oral exposure to zirconium dioxide (an insoluble zirconium compound) may be even lower than after repeated oral exposure to zirconium acetate (a 'water soluble' zirconium compound).
Level of HZC in diet: 0%, 0.2%, 2.0% and 20%
Total intake food: 2182 g, 2176 g, 2149 g and 2475 g
Total intake ZrO2: 0 g, 0.9 g, 9.0 g and 103.5 g
Total intake water: 4193 g, 4774 g, 4097 g and 4021 g
Initial weight males: 52-54 g; females: 50-51 g
Weight after 17 weeks males: 340-349 g; females 210-230 g
Weight gain (average) males: 285-295 g; females 160-179 g
Daily consumption of HZC: 0, 0.13-0.30 g/kg, 1.3-3.3 g/kg and 15.1-33.9
The overall results of the test formulation
analyses were within the limits of acceptance for concentration (15% of
the theoretical concentration).
Based on the available data for repeated dose toxicity via the oral route according to the CLP criteria, zirconium dioxide should not be classified for STOT - repeated exposure. Based on the read across assumption that the addition of erbium (oxide) to the crystal lattice of zirconium dioxide does not alter the unhazardous character of zirconium dioxide, it is considered acceptable to assume non-classification for erbium zirconium oxide too.
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