Iron yellow is a kind of oxide made from iron. It has stable chemical properties and is widely used in paint, scagliola, and concrete. It is a highly opacified, bright color, and is weatherproof. In addition to these properties, it is also a good colorant for rubber, paper, and ink. This is the reason why it is often used as a colorant in cosmetics.
The chemical composition of iron oxide is a mixture of two types of iron oxides. The red type of iron oxide has primary particles of about 100 nm, while the yellow one has only a small amount. Yellow iron holds water more than white iron, and dries more slowly. Once it reaches cone 8, it takes on the characteristics of metal. The white one is much lighter than the yellow one, and is also a more opaque color.
In determining the composition of iron oxides, the EU Commission has created the FAO JECFA monograph. This is an internationally accepted method for identifying iron oxides in feed. It is also recommended by Commission Directive 2008/128/EC, which defines purity criteria for food colours. The monograph involves the measurement of iron concentration by solubility in various solvents, digestion, and iodometric titration. However, it does not require an appropriate laboratory for identification or quantification.
In addition to being an irritant to the skin and eyes, iron oxides also have a potential to cause cancer. However, the Panel noted that no studies have been conducted to determine whether these additives are genotoxic. Consequently, the risk of cancer from the use of these products should be low. This is why they are widely used in cosmetics. But it is important to remember that you must check the safety of any products before deciding to use them.