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Sunscreen

What to Look For

Skin cancer is the most common of all cancers in the U.S., and as many as one million people are diagnosed with it every year. Despite these high numbers, skin cancer is preventable with proper protection.

Mineral Ingredients

Titanium dioxide and zinc oxide are minerals that physically block ultraviolet (UV) rays from reaching your skin, as opposed to other sunscreens that use chemicals to absorb UV rays. Minerals are considered the best protection against sunburn because they block both UVB rays (which cause sunburns) and UVA rays (which cause skin aging and cancer). Chemical sunscreens, on the other hand, don't always protect against UVA. And some break down in sunlight in as little as half an hour, while also interfering with your hormonal systems (see The Backstory).

All the sunscreens listed on our Product Comparisons page use either titanium dioxide, zinc oxide or a combination of both. None contain chemical sunscreens.

Protection Rating

SPF (or sun protection factor) is an FDA-regulated rating system that represents how long it will take for exposed skin to burn with the sunscreen applied. For example, if your unprotected skin usually burns in 10 minutes, a sunscreen with an SPF 15 would prevent a sunburn for 15 times that length of time, or 150 minutes (two and a half hours). However, SPF only rates UVB rays, not skin damaging UVA rays. For that reason, never rely entirely on a sunscreen's SPF, and look for products that advertise "broad-spectrum protection," which means it protects against both types of rays.

Fabrics and sun-protective clothing are rated according to UPF (ultraviolet protection factor), which measures how well these items prevent sunburn in the same way that SPF does. While UPF does apply to both UVA and UVB rays, UPF claims aren't federally regulated, as SPF ratings are.

Nano-sized or Micronized Particles?

The primary drawback to sunscreens with titanium dioxide or zinc oxide is that they can leave a white tint on your skin. To make the lotions transparent, manufacturers shrink titanium dioxide or zinc oxide particles down to nano-sized particles--less than 100 nanometers (nm); for comparison, a human hair is about 80,000 nm in diameter. Because smaller particles can act differently than larger particles when they enter the body, these nano-sized particles have been cause for concern: Research indicates that nanoparticles of titanium dioxide are small enough to bypass your body's "blood-brain barrier" (a natural defense against foreign substances in the bloodstream) and enter the brain where they can damage brain cells. Larger particles, however, are blocked by that barrier and don't pose this problem. Fortunately, a 2006 Australian government literature review on the topic found that neither titanium dioxide nor zinc oxide penetrate the skin deep enough to actually enter the bloodstream, and most scientific evidence supports the fact that nano-sized particles of these ingredients are often trapped in the outer layer of the skin and not absorbed (they should always be avoided when used in powders that may be inhaled). However, if you'd rather err on the side of safety, opt for sunscreens that use micronized ingredients (particles larger than 100 nm), which are mostly transparent but may still offer a slight tint.