Almost all sunscreens contain a chemical known as avobenzone. While this chemical is the best option for filtering harmful ultraviolet A (UVA) sun rays, exposure to sunlight can still break it down. Most sunscreens also have octocrylene to help stabilize the avobenzone. Octocrylene may have faults of its own, however. According to the Environmental Working Group (EWG), it may irritate the skin and disrupt the body's hormone system.
