Do you know that many sunscreens have chemicals that are bad for you and may even increase free radical damage. The Environmental Work Group (EWG) has identified many of these chemicals and what the issues with them are.
Some of the issues include toxicity to reproductive organs, bioaccumulative in the body, breaking down other more effective sunscreen ingredients, contributing to free radicals that can cause damage to skin DNA which can increase susceptibility to skin cancer.
This, of course is a very short version of the issues.
The bottom line: natural sunscreen ingredients are safer. Read the label and look for Zinc Oxide and or Titanium Dioxide. These are the safest and best to use and apply to your skin.