SPFs can reach triple digits, but the benefit is marginal.

By CATHERINE SAINT LOUIS


Last year, Coppertone introduced two easy-to-use sprays with its highest-ever sun protection factor: SPF 70+. Not to be outdone, Neutrogena offered its Ultra Sheer Dry-Touch lotion in SPF 85 strength.

This sun season, Banana Boat is retaliating with a pair of SPF 85 sprays, which it trumpets on its Web site as“our highest SPF level in a continuous spray formula.”

But now, SPF creep has hit the triple digits with Neutrogena’s SPF 100+ sunblock, leading some dermatologists to complain that this is merely a numbers game that confuses consumers.

The parade of stratospheric SPFs is“crazy,”said Dr.Barbara A.Gilchrest, a dermatology professor at Boston University School of Medicine.“For a normal person who is fairskinned and concerned about skin damage and photoaging,”Dr.Gilchrest said,“it’s really in my opinion tremendous overkill.”

A sunscreen’s SPF, or sun protection factor, measures how much the product shields the sun’s shorter-wave ultraviolet B rays, known as UVB radiation, which can cause sunburn. It used to be that SPF topped out at 30. No more. These days, a race is on among sunscreen makers to create th highest SPF.

If adequately applied, sunscreens with sky-high SPFs offer slightly better protection against lobster-red burns than an SPF 30. But they don’t necessarily offer stellar protection against the more deeply penetrating ultraviolet A radiation, or so-called aging rays.


In 2007, the United States Food and Drug Administration proposed capping SPF at 50+, but it still isn’t in place. So in the cap’s absence, a marketing battle is raging, fought on territory best understood by beachgoers.

“It captures the consumers’attention, the high SPF,”said Dr.Elma D.Baron, an assistant professor of dermatology at Case Western Reserve University in Ohio.

But no SPF, not even 100+, offers 100 percent protection. What’s more, both UVA and UVB radiation can lead to skin cancer, which is why dermatologists now advise using sunscreens with an SPF of at least 15 and UVA-fighting ingredients like an avobenzone that doesn’t degrade in light or Mexoryl SX.

The difference in UVB protection between an SPF 100 and SPF 50 is marginal. Far from offering double the blockage, SPF 100 blocks 99 percent of UVB rays, while SPF 50 blocks 98 percent. (SPF 30 deflects 96.7 percent).

A sunscreen’s SPF number is calculated by comparing the time needed for a person to burn unprotected with how long it takes for that person to burn wearing sunscreen. So a person who turns red after 20 minutes of unprotected sun exposure is theoretically protected 15 times longer if they adequately apply SPF 15. Dermatologists advise reapplication every two hours or after swimming or sweating.

“As you get higher and higher, it’s not really a practical difference,”said Dr.David M.Pariser, the president of the American Academy of Dermatology. But to get the SPF advertised, you must use a full shot glass on your body. That’s an ounce (28 grams), which means a three-ounce tube should last, at most, a few outings.

Yohini Appa, the senior director of scientific affairs at Johnson & Johnson, of which Neutrogena is a subsidiary, said Neutrogena’s SPF 100+ lotion provided for realworld under-application. With it, she said,“you can bring the least diligent ones up to the level of the most diligent ones.”

Banana Boat has a similar rationale for its SPF 85 sprays, which provide“an extra ayer of insurance for consumers,”said Beth St.Raymond, the director of sun care at Energizer Personal Care, of which Banana Boat is abrand.

But that logic may be flawed. It has long been assumed that applying half the recommended ounce meant half the SPF protection. But a small 2007 study published in the British Journal of Dermatology found that under-application made SPF coverage fall much more steeply.

“It turns out that if you apply half the amount, you get the protection of only the square root of the SPF,”said Dr.Darrell S.Rigel, a clinical professor of dermatology at New York University, who has done efficacy testing for Johnson & Johnson and the Procter & Gamble Company.

So applying a half-ounce of SPF 70 will not give you the protection of SPF 35, but 8.4, Dr.Rigel said.

What if high-SPF products allow beachgoers to dawdle without turning a telltale red?“It could actually be a negative thing,”said Sonya Lunder, a senior analyst at the Environmental Working Group, a nonprofit in Washington that reviewed nearly 1,100 sunscreens in 2008,“because it allows you to stay in the sun longer.”And, she added,“You could be getting other sun-related damage.”