Inert earth mineral used as a thickening, lubricating, and sunscreen active ingredient in cosmetics. Along with titanium dioxide, zinc oxide is considered to have no risk of skin sensitization. As a sunscreen, it is effective in providing protection against sun’s UVA rays in addition to UVB rays. Zinc oxide is also sometimes used in makeup to impart opacity to products like foundations, particularly powder-based makeup.
In recent years, there have been concerns about the use of nano-sized zinc oxide in sunscreen formulations. Nanotechnology is about taking a material and making it much smaller than its original size. In the case of zinc oxide, nanotechnology is used to make it more aesthetically pleasing, as well as enhance its SPF. Nano-sized zinc oxide is not believed to be a safety concern for skin.
References for this information:
Particle and Fibre Toxicology, August 2016, page 44
International Journal of Cosmetic Science, June 2014, pages 273-283
Indian Journal of Dermatology, September-October 2012, pages 335-342
Archives of Toxicology, July 2012, pages 1063-1075
Photodermatology, Photoimmunology, & Photomedicine, April 2011, pages 58-67
American Journal of Clinical Dermatology, December 2010, pages 413-421