"The rules will transform the $680 million domestic market for sunscreens, which has been growing rapidly because of an aging population and growing worries about skin cancer."
First, some facts about sun and current sunscreen labels. There are two kinds of solar rays: short ones called UVB that cause burning and skin cancer and long ones called UVA that cause skin cancer and wrinkling. SPF ratings — the letters stand for sun protection factor — reflect only the extent of protection against UVB. The higher the rating, the longer one can stay in the sun before burning.
But there are two important caveats. First, SPF ratings are based on a rather thick application of sunscreen, not the amount consumers normally use, which is most often a quarter to a half the amount applied in manufacturers’ tests. An adult in a bathing suit should apply about three tablespoons of lotion every two hours, experts say.
Second, above an SPF of 30, which can block 97 percent of UVB (if used in testing amounts), effectiveness increases by only 1 or 2 percent. In the way that sunscreens are used in the real world, then, a product with an SPF of 30 actually provides the protection of SPF 2.3 to 5.5, and one rated SPF 50 provides the protection of SPF 2.7 to 7.1, according to a report published this month in Drug and Therapeutics Bulletin.
UVA, which represents more than 95 percent of solar radiation reaching the earth, does not figure in SPF ratings. The phrase “broad spectrum” is meant to indicate protection against UVA, but there is no numerical rating for product effectiveness. Under the new rules, products labeled “broad spectrum” will have to provide equal protection against UVB and UVA, and only products with an SPF of 15 or higher will be allowed to claim protection against skin cancer and premature skin aging.
Meanwhile, dermatologists suggest choosing only products that are labeled “broad spectrum” and have an SPF rating of 30 to 50. There is no evidence that anything higher than 50 is any better. Apply the sunscreen just before exposure, and reapply it two hours later — it loses effectiveness over time. And even if the label claims the sunscreen is water resistant, be sure to reapply it after swimming or sweating heavily.
The rise in melanoma has led to fears that sunscreens may actually cause this deadly cancer. But other explanations are more likely. By allowing people to stay in the sun longer, sunscreens have greatly increased exposure to UVA radiation. And many, if not most, victims of melanoma were damaged long before sunscreens became popular. A history of sunburn is a major risk factor for this cancer; five sunburns per decade raise the risk by about threefold.
Another reason for the increase in diagnoses: skin cancer screening and detection have improved greatly in recent decades.
With regard to ingredients, many dermatologists recommend products with micronized titanium or zinc oxide as the most effective sun blockers that leave no white residue on the skin. There is some concern, based on animal studies, that the most popular ingredient in sunscreens, oxybenzone, may disrupt natural hormones, but the scientific evidence is scant.
Another chemical, retinyl palmitate, sometimes listed among the inactive ingredients, has been linked to skin cancers in animal studies. Because it is converted into a compound that can cause birth defects, it should be avoided by women who are pregnant or likely to become pregnant.
However, although more studies of these possible risks should be done, Consumer Reports concluded that “the proven benefits of sunscreen outweigh any potential risks.”
Finally, don’t be fooled by price. In tests of 22 sunscreens, Consumer Reports found nine to be effective against UVB and UVA and ranked three as “Best Buys”: Up & Up Sport SPF spray (88 cents an ounce) at Target; No-Ad With Aloe and Vitamin E SPF 45 lotion (59 cents); and Equate Baby SPF 50 lotion (63 cents). The organization said La Roche-Posay Anthelios SPF 40 cream, at $18.82 an ounce, scored well below these three in effectiveness.
Although it may be tempting to try to kill two birds at once with a combination sunscreen and insect repellent, the Centers for Disease Control and Prevention does not recommend this. Multiple applications could result in an overdose of the repellent.
More than two million people in the United States are treated each year for the two most common types of skin cancer, basal cell and squamous cell, and more than 68,000 receive a diagnosis of melanoma, the most deadly form of the disease. Sunscreens have not been shown to prevent the first case of basal cell carcinoma, but they delay reoccurrences of basal cell and have been shown to prevent squamous cell and melanoma.