A number of studies suggest that the use of sunscreen does not significantly decrease the risk skin cancer, and may actually increase the risk of sunburns. People seem to forget that the sun sends two types of harmful rays: UVA and UVB. Most sunscreens protect just against UVB. Even though UVA rays don’t cause sunburn, they penetrate deeper into the skin and cause damage to DNA. The Environmental Working Group (EWG), a Washington-based research group, did a study which showed that many sunscreens are ineffective or contain harmful chemicals.