http://www.newscientist.com/article/dn8937-sunscreen-chemicals-disrupt-thyroid-in-rats.html
UV light from the Sun can potentially cause skin cancer. But studies on the chemicals that block UV have already raised concerns over side effects.
I’m feeling more and more secure about my decision to just avoid leaving the house entirely. No sunstroke, no UV, no chemical-induced cancer, plus I get a lot more Stumbling done. 😉