The Environmental Working Group independently tested 1400 SPF-rated products. Only 8 percent of the sunscreens offer sufficient protection and healthier ingredients to earn a "green" rating. EWG had two main concerns about sunscreen -- the false sense of protection that they offer, and the chemicals that they contain.
Some sunscreens contain oxybenzone, which blocks UVA and UVB but gets absorbed into your skin, acting as a photosensitizer. Because of this, it is very likely a photocarcinogen, and it is also a hormone disruptor.
What’s more, according to Treehugger:
“Recently available data from an FDA study indicate that a form of vitamin A, retinyl palmitate, when applied to the skin in the presence of sunlight, may speed the development of skin tumors and lesions (NTP 2009). This evidence is troubling because the sunscreen industry adds vitamin A to 41 percent of all sunscreens.”