Recent research suggests that sunscreen can actually damage your skin, by releasing more free radicals then not using it.

According to this 2006 study from the University of California, Riverside, certain sunscreen ingredients may cause more free radicals to form than no sunscreen at all. If the findings are confirmed, the implications will be enormous — and sobering, given that women have been told for decades that regular sunscreen use is one of the best ways to minimize aging and the risk of skin cancer.

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Chemical sunscreens have three primary defects: 

1	They are powerful free radical generators.	Their free radical generation increases cellular damage and changes that lead to cancer.  Psoralen – such a compound that is used to treat psoriasis increases skin cancer rates 83-fold.
2	They often have strong estrogenic activity.	Estrogenic – “Gender Bending” – chemicals interfere with normal sexual development -   Engendering a host of secondary medical problems – see more below.
3	They are synthetic chemicals that are alien to the human body and accumulate in body fat stores.	The human body is well adapted to de-toxify biologicals that it has been exposed to over tens of millions of years. But it has often has difficulty removing new and non-biological compounds such DDT, Dioxin, PCBs, and chemical sunscreens.

Source 2

In fact This website has so much more information then i could accumulate, i will tell you to go there if you are interested in knowing more!

From this source

And another source

Be careful out there!