Chemistry of tanning

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.

---

---