Formula: FeO(OH).H2O or Fe(OH)3
Other names: Iron (III) hydroxide, hydrated iron oxide
Appearance: Lemon to dark yellow powder
Solubility in water: Insoluble
Thermal decomposition: Dehydrates to red iron oxide between 80 and 160°C
Melting Point: Not applicable due to thermal decomposition
Colourant for glazes
No adverse effects
The prolonged inhalation of high concentrations can produce a benign pneumoconiosis without impairment of lung morphology, function or symptoms. Although this may show up on lung X-rays, unlike silica this does not result in fibros or other damage to the lungs.
Particles are rods about 1.6µm long but with the diameter mostly below 0.1µm.
Only about 2% of ingested yellow iron oxide is absorbed by the digestive system (though this increases markedly with ascorbic acid - Vitamin C).
There are very few toxicity tests on this material, but also there are no known toxicity reports other than from the generic dust hazards.
Results from red iron oxide should not be read across, due to the much higher proportion of nanoparticles in the yellow oxide.
The material is not reported to have any genotoxicity.
The material is not reported to be a carcinogen.
There is no data on effects on fertility, reproductive toxicity or effects on or via lactation.
Normal dust precautions.
Normal waste disposal. Not harmful to aquatic life.