Registration Dossier

Administrative data

Description of key information

Diniobium pentaoxide is not bioavailable. Repeated dose oral: NOAEL 1000mg/kg bw/day. Other routes tests are unnecessary.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion
Dose descriptor:
1 000 mg/kg bw/day

Additional information

Diniobium pentaoxide is insoluble in water. It is resistant to acids, including nitrohydrochloric acid (aqua regia), HCl, H2SO4, HNO3, and H3PO4 and to many organic and inorganic compounds. Diniobium pentaoxide is attacked by hot concentrated mineral acids, such as HF and HF/HNO3mixtures, but is resistant to fused alkali (Nowak & Ziolek,Chem. Rev. 1999,99, 3603-3624). I.e., diniobium pentaoxide is dissolved only under extremely oxidising conditions that are not compatible with administration to animals.

Due to its insolubility it can be assumed that diniobium pentaoxide even if applied as pure powder will not be absorbed in the stomach and intestinal tract. The negligible bioavailability after oral application allows the prediction that the NOAEL for toxicity after repeated oral exposure will be greater than 1000 mg/kg bw/day.This value was confirmed by the performed study.

This predictability makes repeated dose inhalation toxicity testing unnecessary. A similar rationale forbids the testing via the dermal route: since it is certainly predictable that diniobium pentaoxide as manufacured cannot penetrate the skin, any testing via this route is scientifically unjustified.

Justification for classification or non-classification

Repeated dose oral: NOAEL 1000mg/kg bw/day.