ZnO emits a greater amount of electrons than TiO2 and the anatase form emits more than rutile form. The obvious concern is that the ROS formed by UV-exposed TiO2 and ZnO have the potential to damage proteins, lipids, and DNA they contact. Of note, mineral sunscreens lacking nanoingredients have been marketed and used under UV exposure for years, but there are no studies demonstrating the production of potentially harmful free radicals with these traditional sunscreens. If these studies were to be undertaken, the larger particles in mineral sunscreens would have less surface area to react with UV light and thus, be less likely to form such ROS. Several studies have been conducted to address the concern of free radicaleinduced DNA damage and we have summarized their findings below.