What Is Zinc Oxide?

Zinc Oxide (ZnO) is an inorganic cosmetic ingredient widely used in cosmetics and personal care products. It is also known as CI 77947 and is used as a colourant in cosmetic formulations.

The ingredient has several cosmetic functions, including colour, skin protection and UV absorption. Its applications and permitted uses depend on the regulatory requirements of the relevant market and on the physical characteristics of the Zinc Oxide used.

Cosmetic Applications of Zinc Oxide

Colourant

Zinc Oxide is used as a white colourant in cosmetic and personal care products. It can be used in products applied to areas including the lips and eye area when the applicable specifications are met.

Skin-Protecting Products

Zinc Oxide is used in skin-protecting formulations and is particularly well known for its use in products designed to protect the skin.

Sunscreen Formulations

Zinc Oxide can function as a UV filter in sunscreen formulations. Its ability to absorb and scatter UV radiation makes it an important ingredient in mineral sunscreen products.

Zinc Oxide Nanomaterials in Cosmetics

The properties of Zinc Oxide can vary depending on particle size, morphology, purity and surface treatment. For this reason, nano-sized Zinc Oxide requires specific consideration in cosmetic formulation and safety assessment.

The SCCS has evaluated specific Zinc Oxide nanomaterials for use as UV filters. The materials evaluated include nanoparticles with a purity of at least 96%, a wurtzite crystalline structure and defined particle-size characteristics.

For the evaluated materials, the median particle diameter (D50) is above 30 nm and D1 is above 20 nm.

The evaluated nanoparticles may be uncoated or coated with specific surface treatments, including triethoxycaprylylsilane, dimethicone, dimethoxydiphenylsilanetriethoxycaprylylsilane cross-polymer or octyl triethoxy silane. Other coatings require appropriate safety evaluation and should not adversely affect the relevant particle properties.

Formulation Considerations

When using Zinc Oxide in cosmetic formulations, the intended function, particle characteristics and regulatory status should be considered carefully.

For sunscreen products, particular attention should be given to whether the Zinc Oxide is used in pigmentary or nano form and whether the specific material complies with the applicable regulatory requirements.

Ingredient Information

INCI: Zinc Oxide
CAS: 1314-13-2
EINECS/EC: 215-222-5
Colour Index: CI 77947

References

Source: Handbook of Cosmetic Ingredients: Their Use, Safety and Toxicology – Anthony Dweck.