Skin cancer rates in America continue to rise, despite the amount of sunscreen people are slathering on. Now, new FDA testing shows that the active ingredients in sunscreen, normally absorbed into the body, may remain for days or even weeks. In addition, their testing found that even a single application of sunscreen seemed to leach high concentrations of chemicals into the bloodstream — beyond what the FDA considers safe. So, what exactly are these ingredients and how harmful are they?