Study: 4 in 10 popular sunscreens fail to protect skin

A whopping 40 percent of the most-popular sunscreens do not adequately protect against sun damage, new research shows.

And on top of that, consumers spend up to 3,000 percent more for products that provide the same sunscreen protection as lower-cost sunscreens.

Scientists from Northwestern University's Feinberg School of Medicine looked at the top one percent of highly-rated sunscreens sold on Amazon.com. The cheapest sunscreen was 68 cents an ounce, and the most expensive was $24 an ounce.

Of the 65 products identified, 26 failed to meet guidelines set by the American Academy of Dermatology.

The recommendations call for products to provide:

• Broad spectrum protection covering both UVA and UVB rays.

• Sun Protection Factor (SPF) of at least 30.

Researchers conducted the study in order to come up with recommendations for effective, affordable and popular sunscreen products to recommend to people. Their findings were recently published in the journal, JAMA Dermatology.

Melanoma rates have tripled in the last 30 years, and dermatologists say wearing the right sunscreen reduces the risk of skin cancers, sunburns and other skin damage. Still, convincing people to regularly wear sunscreen remains a battle.

In the study, researchers analyzed consumer reviews of sunscreen products and rated which factors were most important to people. Cosmetic features, such as how the product felt, looked and smelled, dominated consumer comments.

"You don't want to wear a chalky, greasy, terrible-smelling product, even if your dermatologist recommends it, " lead author Dr. Steve Xu said in a statement. "This gave us insight into what consumers prefer, so it can guide our recommendations and be cost conscious."

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