It was one of the more surprising findings to hit the news in recent years: According to a 2011 study, frequent sunscreen wearers are 23 percent more likely to burn than those who use it rarely. It’s enough to make you want to toss out your sunscreen. But not so fast. The problem is not necessarily with sunscreens themselves but rather with how they’re labeled and how we’re using them — or misusing them. The Food and Drug Administration set up sunscreen rules designed to clear up any confusion.