Sunscreen

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The FDA's long-awaited sunscreen-labeling reforms, which take effect in 2012, address concerns that consumers don't fully understand how--or how well--sunscreen combats damage done by the sun

HOW SKIN GETS BURNED

1 When skin is exposed to the sun, UV rays stimulate cells in the bottom layer of the epidermis

Epidermis

2 Pigment cells go to work, producing melanin, which darkens skin and protects DNA

Melanin

3 When the melanin defense is overwhelmed, cell damage occurs, and the body boosts blood flow to aid healing, causing inflammation

Dermis

Blood flow

UVA rays, responsible for most UV radiation reaching the earth, penetrate deeply and may contribute to cancer and aging

UVB rays, higher in energy and more variable with time of day and season, cause sunburn, increasing cancer risk

Sunscreen

UV rays

SUNSCREEN FIGHTS BACK

On the surface

Sunscreen contains compounds like zinc oxide that act as a UV barrier and absorb or reflect rays before they ever touch the body

Sunscreen molecules

In the skin

Some UV energy makes it through. Sunscreen molecules convert damaging UV to less harmful energy, which then radiates back out