Originally Posted by Ronaldo10

We have learned that there is actually no safe level of UV exposure (this is the part of sun exposure and tanning beds that actually causes tanning). The fact is, UV light is high energy and as it penetrates our cells it occasionally penetrates the nucleas of the cell and actually damages the DNA itself. It can cause breaks in the DNA, or cause the wrong base pairs to be permanently fused etc. This causes things in the cell to go awry. Usually our bodies can clean up these cells. But every now and then these so called "mutations" allow them to escape the normal cell cycle and also our own bodies way to get rid of these out-of-control cells and thus you have cancer.