For most natural products retailers, when summer sets in, sunscreen sales spike. And in recent years, heightened awareness of skin cancer has pushed even more people to purchase and use sunscreen. According to Schaumburg, Ill.-based market research firm SPINS, sales of natural sun protection and tanning lotions shot up 25 percent in natural products stores in 2010. Last year's sharp growth, coupled with a few other key factors, suggests that this season, perhaps more than ever, consumers will kick Coppertone out of the cabana in favor of natural, mineral-based blocks. Here's why.