Iron

Endpoint summary

Description of key information

There are no reports in the literature on skin and eye irritation with metallic iron. Skin contact with iron has been very common in domestic life and during work for a very long time. This has never resulted in any report in the literature pointing to dermal irritation. As regards eye irritation, it can be argued that any damage to the eye can only have a mechanical background, also in cases where the iron is oxidised. Also the very extensive experience with the possible exposure of the eyes during abrasive techniques has never resulted in reports pointing to eye irritation that cannot be attributed to mechanical damage. Thus for both endpoints testing is deemed unnecessary. This is further justified by the lack of irritating properties observed in skin and eye-irritation tests with iron oxides, which are summarized under this endpoint. The acute inhalation studies did not show any adverse effects and strongly suggests thereby that the 6 h inhalation of up to 250 mg/m3 does not cause respiratory irritation.

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Additional information

There are no reports in the literature on skin irritation with metallic iron. Dermal contact with metallic iron has been a common feature of everyday life for humans for thousands of years, whether in the domestic sphere or during work. If metallic iron exhibited skin-irritating or eye-irritating properties, these would certainly not have gone unnoticed. No reports exist in the literature of skin irritation in humans due to contact with metallic iron. The requirement for a dermal irritation/corrosion study is, therefore, deemed redundant on the basis of a very long history of safe use. 

During contact with the skin, the metallic iron may oxidize. In the unlikely event that exposure time were long enough for any substantial oxidation, this would not result in irritation as is shown by the negative outcome of skin irritation studies with iron oxides.

Similarly, there are no reports in the literature on eye irritation caused by metallic iron. The requirement for an eye irritation study is, therefore, deemed redundant on the basis of a very long history of safe use. Potential occupational exposure of the eye to metallic iron particles substances is very common in machining and construction. The surface of iron objects is often corroded and consequently abrasive techniques, drilling and sawing of the steel will result in particles that contain both metallic iron and its oxides. So there is a lot of experience with handing such exposures, and there is no need to start standard eye irritation studies with animals in the context of prevention or protection. Iron particles cannot be regarded as inert, and will (partially, depending on their size and the duration of exposure) oxidize in the aqueous ocular environment. This will result in iron oxide. Iron oxide itself is inert and will not give rise to effects other than mechanical effects. This is confirmed by the summaries of supporting studies that are included under this endpoint.

Skin irritation/corrosion of iron oxides

Two guideline studies on skin irritation/corrosion of iron oxides were identified in the literature. One study with a mixture of Fe₂O₃83.5 %, FeO 12%, and Co 4.5%, i.e. 95.5% iron oxide; another study with Fe₃O₄. Both studies gave negative results. Additional information is provided by a supporting study performed with FeO(OH), which also gave a negative result. Based on these iron oxides can be considered non-irritating.

Eye irritation of iron oxides

Two guideline studies on eye irritation were available and they were summarized as key studies. One study with a mixture of Fe₂O₃83.5 %, FeO 12%, and Co 4.5%, i.e. 95.5% iron oxide; another study with Fe₃O₄. Both studies gave negative results. Additional information is provided by a supporting study performed with FeO(OH), which also gave a negative result. Based on these results iron oxides can be characterized as non-irritating.

The acute inhalation studies with metallic iron did not show any adverse effects and strongly suggests thereby that the 6 h inhalation of up to 250 mg/m³does not cause respiratory irritation.

Justification for classification or non-classification

Metallic iron and iron furnace need not to be classified for skin, eye or respiratory irritation.