Registration Dossier

Administrative data

Description of key information

Conducting a repeated dose toxicity study with Ytterbium stabilized Zirconium and Hafnium Oxide (target substance) is scientifically not necessary. Due to its low solubility and bio-accessibility, a systemic toxicity of the target substance is not expected. The insolubility of the target substance was confirmed by a Transformation/dissolution assay (see IUCLID section 4.8). Hafnium and zirconium was not detectable. For ytterbium, an average metal release of 0.069 µg/L was measured after 7 days at 100 mg/L mass loading. To evaluate the bio-accessibility of the target substance a bio-elution test was conducted (see IUCLID section 7.1.1). The highest metal release values were found in artificial lysosomal fluid with a metal release for Yb of 8.314 µg/L, for Zr of 4.30 µg/L and for Hf of 0.02 µg/L (which is actually the limit of quantification). For the oral and dermal route, the metal release of hafnium was below the detection limit, for Yb within the range of 0.485 to 3.24 µg/L and for Zr within 0.01-0.02 µg/mL. Thus, the bioavailability of the target substance can be expected to very low. Furthermore, available data from the suitable read-across substances ytterbium oxide and ytterbium chloride supports further, that a systemic toxicity induced by the target substance is not expected.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records
Reference
Endpoint:
short-term repeated dose toxicity: oral
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
other:
Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

Justification for classification or non-classification

Conducting a repeated dose toxicity study with Ytterbium stabilized Zirconium and Hafnium Oxide (target substance) is scientifically not necessary. Due to its low solubility and bio-accessibility, a systemic toxicity of the target substance is not expected. The insolubility of the target substance was confirmed by a Transformation/dissolution assay (see IUCLID section 4.8). Hafnium and zirconium was not detectable. For ytterbium, an average metal release of 0.069 µg/L was measured after 7 days at 100 mg/L mass loading. To evaluate the bio-accessibility of the target substance a bio-elution test was conducted (see IUCLID section 7.1.1). The highest metal release values were found in artificial lysosomal fluid with a metal release for Yb of 8.314 µg/L, for Zr of 4.30 µg/L and for Hf of 0.02 µg/L (which is actually the limit of quantification). For the oral and dermal route, the metal release of hafnium was below the detection limit, for Yb within the range of 0.485 to 3.24 µg/L and for Zr within 0.01-0.02 µg/mL. Thus, the bioavailability of the target substance can be expected to very low. Furthermore, available data from the suitable read-across substances ytterbium oxide and ytterbium chloride supports further, that a systemic toxicity induced by the target substance is not expected and no classification is warranted.