Physical or Mineral Blockers include Zinc Oxide and Titanium Dioxide. While ZnO is the only true physical blocker TD works as a hybrid by scattering UV light as well as absorbing UV radiation. Zinc works by sitting on top of skin and either reflecting or scattering UV rays. Zinc Oxide blocks against both UVA and UVB rays, covering the whole spectrum. Zinc Oxide is the only FDA approved Broad Spectrum UVA/UVB Protection ingredient. Zinc Oxide creates a physical barrier that both reflects UV rays away from the skin and effectively blocks UVA1, UVA2 and UVB rays as well. Zinc Oxide won’t degrade or lose potency over time, won’t produce the skin sensitivities and rashes or initiate the creation of free radicals or hormone disruptors commonly caused by chemical sunscreens. Zinc Oxide is an insoluble mineral that stays suspended on the skins surface and does not absorb into living skin cells the way Chemical UV absorbers do.
Chemical Absorbers include a range of ingredients. These agents work by interacting with the skin’s top layer to absorb UV rays and convert their energy. Once this energy is absorbed the filters then defuse the energy in to the skin as heat. Chemical sunscreens tend to use a combination of ingredients to protect against the full spectrum of UV rays, as individually they all filter different ranges of the spectrum. While older chemical filters tended to protect well against UVB rays, they often didn’t deliver much in the way of UVA protection. While the new generation of chemical absorbers are much more photo stable there are limits to the amount of UV radiation that they can absorb before breaking down. Some of the chemicals used pass entirely through the blood stream and have been linked to hormone disruption.