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