Sunscreen info. from Chicago Tribune article

...the evidence is inconclusive as to whether sunscreens reduce the risk of basal cell cancer and melanoma, the most deadly form of skin cancer.

Four out of five name-brand sunscreens offer inadequate protection, according to the second annual sunscreen summary by the Environmental Working Group, a non-profit environmental research organization. Leading brands—Coppertone, Banana Boat and Neutrogena—were the worst offenders according to the group, which recommended 143 products at cosmeticsdatabase.com.

The oxybenzone debate. The EWG recommends avoiding sunscreens containing the commonly used chemical oxybenzone out of concern that it can disrupt hormones, cause allergic reactions and damage cells.
But the American Academy of Dermatology (AAD) recommends oxybenzone because it ensures "broad-spectrum" coverage, which means it filters out both UVA and UVB light. Pick your side.
Be wary of "seals of approval." [They can have corrupt ties.]

Don't rely on SPFs. The Sun Protection Factor numbers (SPFs) refer only to the ability to deflect UVB rays. Look for "broad spectrum" to protect against both UVA and UVB rays. An SPF 30 screens 97 percent of UVB rays; an SPF 15 screens 93 percent of UVB rays. Rather than reach for SPF 70, apply a lower number generously and often.

Use at least 7 percent zinc oxide or titanium dioxide. Zinc and titanium act as a physical barrier on the skin and, unlike other sunscreen chemicals, don't penetrate the skin, don't show hormone-like activity, don't break down in the sun and block a wider spectrum of the sun's rays than other products.