Chemistry of tanning
by American Chemical Society. Contact Tiffany Steele McAvoy
It's no coincidence that the process of turning animal
skins into leather is called tanning. When people tan, UV radiation from the sun
breaks down protein in our skin cells and causes, over time, wrinkles and
leathery-looking skin. According to the American Academy of Dermatology (AAD),
most sun exposure occurs before the age of 18. With major summer "beach time"
remaining, here's some information from the American Chemical Society, the
world's largest scientific society, on how consumers can protect themselves and
their families from the sun's harmful rays:
Perfect tan made in the shade: Everyone knows that too much exposure
to the sun can cause skin cancer and premature aging. Everyone from Jennifer
Aniston to your neighbor is using self-tanners to recreate that coveted bronze
glow. But how do they work and are they safe? According to Chemical &
Engineering News, self-tanners contain an active ingredient called
dihydroxyacetone (DHA), a nontoxic, simple sugar found in baby formula and fish
oil. DHA turns skin brown in a process called the Maillard reaction, better
known to food chemists for making beer golden brown. Proteins in our skin
interact with sugars to create brown or golden-brown compounds. DHA doesn't
penetrate further than the outermost, dead layer of skin.
Making sense of sunscreens: From moisturizers to lipsticks, sales of
personal care products formulated with sunscreen have exploded. The sun's rays
are more damaging now then ever because the earth's protective ozone layer is
depleted, but with 17 active sunscreen ingredients approved for use in the
United States, how do you choose? According to Chemical & Engineering
News, sunscreens with inorganic ingredients such as titanium dioxide and
zinc oxide reflect and scatter UV light. Sunscreens made with organic
ingredients like OMC and avobenzone absorb UV light and dissipate it as heat.
SPF (sun protection factor) measures how effectively a sunscreen protects
against UVB rays that burn skin.
Newer sunscreens offer greater protection against sun's rays: Craig
Bonda, a chemist at the C.P. Hall Company in Bedford Park, Ill., has developed a
longer-lasting sunscreen that protects wearers against both UVB and UVA
radiation. Until recently, most sunscreens protected only against UVB — the
ultraviolet rays that cause sunburn. The newest sunscreens absorb or reflect the
full spectrum of ultraviolet radiation, including UVA, which causes skin to age
and wrinkle prematurely and may also cause certain skin cancers. Avobenzone, a
chemical used in many full-spectrum sunscreens, loses its effectiveness upon
prolonged exposure to the sun. Bonda found that avobenzone breaks down more
slowly when the chemical DEHN is added.
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