ACS Chemistry for Life

We’ve always known that sun can burn our skin. But now we also know that long exposure to the sun’s ultraviolet rays can prematurely age skin and ultimately lead to skin cancer. Add to those worries the depletion of upper atmospheric ozone.

It’s no surprise then that sunscreen sales to beach and pool goers are on the rise. And active sunscreen ingredients are also finding their way into a variety of daily-use personal care products, such as moisturizers, eyeshadow, foundations, and lipsticks. Annual sunscreen actives sales in the U.S. and Europe are each about $100 million and are likely to grow 4% annually through 2006, according to industry consultant Kline & Co.

There are two basic types of active ingredients: inorganic and organic. Both afford protection against UV-B rays in the 280- to 320-nm range, the primary culprits in sunburn. Some offer additional protection from UV-A rays in the 320- to 400-nm range, which can penetrate more deeply into the skin and do greater long-term damage.

Inorganic sunscreens use titanium dioxide and zinc oxide. They work primarily by reflecting and scattering UV light. The organics include widely used ingredients such as octyl methoxycinnamate (OMC), 4-methylbenzylidene camphor (4-MBC), avobenzone, oxybenzone, and homosalate. They work primarily by absorbing UV light and dissipating it as heat.

Formulators often combine inorganic and organic sunscreens for a synergistic effect. In fact, that is how most are capable of achieving very high SPF–sun protection factor–ratings. SPF is a measure of how effectively a sunscreen in a formulation limits skin exposure to the UV-B rays that burn skin. The higher the number, the more protection a sunscreen formula affords against sunburn.

Visit “What’s That Stuff” to read more about sunscreen.

Excerpted with permission, Chemical & Engineering News
Copyright © 2002 American Chemical Society