The sunblock you are using may be destroying your skin.  The culprit is Methylparaben.  This preservative is used in most sunblocks as well as many shampoos, conditioners, and skin products.  Researchers (who published their findings in the prestigious journal, Toxicology) found that when methylparaben is exposed to sunlight it results in the following:

• Cell death
• Oxidative stress (related to aging and cancer)
• Lipid peroxidation (creating free radicals and destroying the healthy fats in your skin)

The researchers concluded "These results indicate that Methylparaben, which has been considered a safe preservative in cosmetics, may have harmful effects on human skin when exposed to sunlight."

As for methylparaben being safe, several studies have shown it to be a xenestrogen--a chemical that binds estrogen receptors and alters physiology.  Most importantly, it has been linked to breast cancer--as you will read in this study.  Stay away from all parabens--read your labels and shop accordingly! 

Read the study here.