Q & A Library

Attorneys in California have filed a class action lawsuit on behalf of consumers who, they say, are being intentionally deceived by manufacturers of some of the most popular and widely-sold sunscreens. The suit alleges that sunscreen labels and advertisements mislead the public by suggesting that they completely block the sun's harmful rays. As a result, the lawyers claim, millions of Americans mistakenly believe that their sunscreens adequately protect them from sun damage and skin cancer.

The suit notes that sunscreens afford some protection against ultraviolet (UV) B rays that cause bad sunburns, tan skin and are associated with the two most common types of skin cancer, basal cell carcinoma and squamous cell carcinoma. These two skin cancers tend not to spread and are usually curable by simple dermatological treatments. The suit charges that sunscreen labels and ads mislead the public when they claim to block UVA rays, which penetrate the skin more deeply than UVB and have been linked to melanoma, the form of skin cancer that metastasizes early and is often fatal once it does so.

It's true that no sunscreen effectively blocks all UVA rays. Those that do the best job are the ones containing zinc oxide, Parsol 1789, and titanium dioxide.

I'm not going to make any judgments about the merits of the lawsuit, but I can tell you how to get the most protection from your sunscreen:

• Use lots of it. You need at least an ounce (the amount that would fill a shot glass) to cover your entire body.
• Apply sunscreen 15 to 30 minutes before going outdoors so that it can be absorbed into the skin.
• Be sure to reapply sunscreen every two hours and after every swim. No matter what the label says, one application of sunscreen won't last you all day and won't stay on if you're in and out of the water.
• Choose sunscreens that offer "broad spectrum" protection - that means it will block UVB rays and some UVA. Look for zinc oxide, titanium dioxide, and Parsol 1789 among the ingredients.
• Buy sunscreen with a minimum SPF of 15. This will block about 93 percent of UVB rays. Higher SPF numbers won't necessarily give you that much greater protection, but tend to remain effective longer.

Andrew Weil, M.D.