It's no secret that overexposure to UV rays either natural sunshine or manufactured produces negative effects. In fact, about 90% of skin cancer incidents are the direct result of UV radiation. The role of tanning beds remains key. Introduced in the U.S. in the 1970s, they've continued growing in popularity, especially among teens, despite well-publicized risks. An April 2010 study showed for the first time that indoor tanners specifically may form dependencies in the same way that drugs and alcohol do.