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The trend for natural color cosmetics and personal care products in general is still popular, but there are differences between mineral and natural colorants, especially when it comes to color additives. The formulator needs to understand the difference and make informed decisions about the pigments they select for a color cosmetic or personal care products.
One example is iron oxides, which are available in red, yellow, black and brown blends. These colorants are considered mineral by most people, as they essentially are derived from the oxidation of iron, with the different colors arising from the different oxidation states of the iron. For cosmetic use in the United States, iron oxides must be synthetic according to the US Code of Federal Regulations Part 21 Section 73.2250, which clearly uses the term “synthetic.” In other words, natural iron oxides cannot be used as color additives for cosmetics and personal care products in the United States because it is much easier to control trace levels of heavy metals in a synthetically produced mineral than it is in a naturally mined mineral.
Many mineral-based color additives (those exempt from government certification) and other powder fillers must be assayed for heavy metal content, specifically lead, arsenic and mercury. They must fall within the guidelines set down by the US Food and Drug Administration (FDA). For iron oxides, the maximum levels for lead, arsenic and mercury are 10, 3, and 3 parts per million (ppm), respectively. Some other ingredients only allow 1 ppm of mercury. Color additives with higher levels of any heavy metals are not considered cosmetically acceptable and cannot be used in cosmetic products. They can, however, be used in other industries such as paints and printing inks.
The use of iron oxides in other countries personal care markets is slightly different. Iron oxides are controlled by the E172 regulation in the European Union. Each cosmetic ingredient in the EU is assigned an “E” number. This number designates its type, form and function as an ingredient for cosmetic use. Even though the cosmetics industry uses that same synthetic iron oxides for all markets, natural iron oxides are permitted for use in cosmetics in the EU but they must be assayed for additional heavy metals in addition to the lead, arsenic and mercury. The additional heavy metals with their maximum limits are cadmium (5 ppm), nickel (50 ppm), copper (50 ppm), barium (50 ppm), chromium (50 ppm) and zinc (100 ppm).
In the United States, iron oxides are grouped and listed together on an ingredient label. In international markets, they must be listed separately and identified by their Color Index numbers: red iron oxide (CI 77491), yellow iron oxide (CI 77492) and black iron oxide (CI 77499).