Registration Dossier

Administrative data

Link to relevant study record(s)

Description of key information

Key value for chemical safety assessment

Additional information

See attached document and the read-across statement attached to summary Toxicological information. The conclusions listed in the first document are reproduced below.

Conclusions

  • Systemic exposure to iron oxides after oral administration is not expected to reach toxicologically significant levels. The physicochemical properties of the substances prevent the necessary dissolution of the oxides themselves or the conversion to iron ions or iron chelates in the gastrointestinal tract.
  • After inhalation of iron oxide particles, the mechanism of pulmonary clearance is activated and the material is removed directly and/or after phagocytosis by the macrophages, via mucociliary transport to the pharyngeal region. Part of this cleared material will subsequently be ingested and eliminated via the faeces. Systemic exposure after inhalation is deemed negligible, since no absorption in the gastrointestinal tract of the insoluble oxides is expected.
  • The iron oxide particles covered by the present dossier are too large to be translocated directly from the alveoli via the epithelium to extrapulmonary organs, a systemic exposure postulated for nanoparticles (MMAD <100 nm).
  • Systemic exposure after intracellular break down of the oxide by the lysosomal system of the macrophages will be negligible, due to the very slow rate of this process. This rate diminishes further when larger particles are ingested.
  • The secondary oral exposure to iron oxides for workers after inhalation at the 3 mg/m3 threshold for respirable inert dust and the 10 mg/m3 threshold for inhalable inert dust will not lead to any substantial systemic exposure, due to the physicochemical properties of iron oxides.