The sun's rays contain UVB radiation, the cause of sunburn, and UVA radiation, which doesn't cause short-term signs of damage, but has a harmful cumulative effect that may be even worse than that caused by UVB. Many studies, such as one reported in a 2001 issue of "Journal of the American Academy of Dermatology," have demonstrated that just one week of unprotected exposure to UVA can cause a host of injuries to the skin, from inflammation to abnormal cell production. To properly protect your skin, the Skin Cancer Foundation says you should look for a sunscreen that provides broad-spectrum protection and not just a sunscreen with a high SPF rating. Knowing which ingredients provide such protection will help.
Avobenzene
Avobenzene is a synthetic ingredient, also known as Parsol 1789 and butyl methoxydibenzoylmethane, which provides protection against all UVA rays, but not UVB. It has to be combined with other ingredients likes oxybenzone to remain effective for any period of time, but new patented technologies such as Helioplex have made avobenzene stable and the most effective UVA block available.
Mexoryl SX
Mexoryl SX is also synthetic, and was developed and patented by L'Oreal, although it was only sold in Europe until the FDA approved its use in 2006. It is effective against the shorter UVA rays, but it does degrade after hours of sun exposure, losing 40 percent of its protection, says Ken Klein, president of Cosmetech Labs, who teaches on the subject of sunscreen formulation for the Society of Cosmetic Chemists. Unlike avobenzene, Mexoryl SX hasn't yet been stabilized via new technologies, and it does carry a slight risk of skin irritation.
Tinosorb
Tinosorb has been approved in Europe and is effective against the entire UVA range, reports a 2001 issue of "Photochemistry and Photobiology." Tinosorb is also very stable, remaining 98.4 percent intact. According to the website Truth in Aging, tinosorb can partly protect other chemical sunscreens from degradation.
Titanium Dioxide
Titanium dioxide is a naturally occurring mineral used to thicken, whiten and lubricate in sunscreens. It provides protection from both UVA and UVB radiation without causing skin irritation. Earlier formulations with this ingredient left a visible white film on skin, but thanks to a new version made up of smaller particles, the latest sunscreens with titanium dioxide have reduced this unwanted side effect.
Zinc Oxide
Zinc oxide is another natural mineral used in the same fashion as titanium dioxide for decades. Like the other mineral, it can leave the same white filmy appearance on the skin, although newer formulations have minimized this. Along with titanium dioxide, it provides the most complete form of sun protection from both UVA and UVB, especially when used in higher concentrations. Unfortunately, this means more of the chalky appearance, which tends to turn off many consumers. As an added benefit, zinc oxide may also have anti-irritant and antioxidant properties, reports the July 2004 edition of the "Journal of Postgraduate Medicine."
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