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Description of key information

A category approach justification for the iron oxides - Fe2O3, Fe3O4, FeOOH, (Fe,Mn)2O3, (Fe,Mn)3O4, ZnFe2O4 - was developed.
In the updated category approach justification, the category was extended and includes additional information on nano- and/or powder material to justify that the category covers nano- and micro-sized materials.
The members of the category are insoluble, inert particles. Conclusive evidence of bioavailable iron or iron particles that were translocated to extrapulmonary organs after inhalation was not observed in repeated dose toxicity studies (see endpoint summary repeated dose toxicity; Pauluhn, 2005). Due to its structure and physicochemical properties (insoluble in water and organic solvents) absorption and bioaccumulation is negligible if no overload effect of the lung occurs – see Category Approach Justification - Iron oxides.

Key value for chemical safety assessment

Bioaccumulation potential:
no bioaccumulation potential

Additional information

As demonstrated in the category approach justification, in regard to structure, physicochemical properties, environmental fate characteristics, ecotoxicity and toxicity, the grouping of Fe2O3 (diiron trioxide), Fe3O4 (triiron tetraoxide), FeOOH (iron hydroxide oxide), (Fe,Mn)2O3 (iron manganese trioxide), (Fe,Mn)3O4 (manganese ferrite), and ZnFe2O4 (zinc ferrite) in the "Iron Oxides Category" is justified.

In the updated category approach justification , the category was extended to nano- and/or powder material. Comprehensive and sufficient data are available to conclude that nano- and micro-sized category member behave similar and no further testing is necessary.

Notably, from the results of repeated dose inhalation studies with FeOOH, Fe2O3 or Fe3O4 any size dependent increased translocation of iron outside the lung did not occur. Therefore no systemic toxicity for nano- and powder material of the iron oxides exists.

These repeated dose toxicity studies demonstrated, that the occupational limit value for nano- and powder material is identical.

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