Understanding the active ingredients in sunscreen is a bit like learning a foreign language that uses a different alphabet. Suffice it to say in short that sunscreens are made up of a combination of two types of ingredients: those that reflect ultraviolet (UV) rays and those that absorb UV rays. Although that might sound simple enough, there are also two types of rays: UV-A rays and UV-B rays. UVB causes sunburn at the outer layers of skin, but UVA causes sun damage that reach deeper layers of skin. Both UVA and UVB radiation can contribute to the development of skin cancer.
Dioxybenzone (benzophenone-8) is an organic compound used in sunscreen to block UVB and UVA rays. It is a derivative of benzophenone. It is insoluble in water, which lends to the ‘waterproof’ claims that sunscreens make.
It’s approved for use in the US at a concentration of 3%.