Hangers&Hangers

I see it everyday, here in Florida. Patients who years ago swore off their ‘baby oil and iodine’ days, who whisper about “laying out” in the sun as if it deserves a confessional…
Yet, they come in perplexed, brown and red, with visible strap marks and brown splotches where the sun has kissed them too much. “I don’t understand. I used a 70.”
Aha! And that’s the problem! Although the F.D.A. has allowed SPFs to be rated up to 30+, it can’t squelch the power of marketing. The marketing Gods want us to believe that an SPF of 70 is twice as good as an SPF of 30. It’s NOT.
And no sunscreen can live up to its SPF (Sun Protection Factor) unless YOU reapply, reapply, reapply.
Let’s go back to how S.P.F. is determined. In a lab, a thick coating of sunscreen (2 mg per square centimeter of skin) is applied. This is a HUGE amount. In real life, most of us use only ½ to 1/4th of this. The skin is exposed to UV radiation, and observed for the tiniest flush of pink. The dose of radiation that turns the skin pink is the MED (minimal erythema dose.) ‘Erythema’, you see, is the medical term for ‘redness.’
So, if a person’s skin turns pink after 10 minutes, then an SPF of 15 should prevent this from happening for 10 X 15 = 150 minutes.
The problem is, this is a LAB, not a BEACH. Some people who just start turning pink in 10 minutes at the beach at 10 a.m. will be roasted lobsters in the same 10 minutes at 1 p.m.
Meanwhile, in real life, other things are happening. You are sweating, and the sun itself is breaking down your sunscreen. Worse, scientists now believe that even more esoteric things are happening—that the chemical sunscreens absorbing the sun’s energy are getting into your skin. When they are overburdened by the energy they can no longer absorb, they release this energy in the form of free radicals right into your skin, causing cancer.
But the good news is, ALL of these problems are prevented by reapplying!
So, I see scorched people who put their SPF 70 on only once. Worse, they’ve been fooled into thinking that a 70 is twice as good as a 30. An SPF of 30 blocks 5% more UVB than an SPF of 15. An SPF of 50 blocks only 1% more than an SPF of 30. Don’t be fooled by marketing. Most Caucasians in Florida should be using a 30+.
The next comment I hear form the “accidentally tanned Floridian” is, “Of course I use sunscreen, when I go out in the sun.” These people are usually quite fit, sporting a tank top and shorts. They’ve had a long day of dropping the kids off, buying groceries, and other errands…without applying sunscreen. How do they do this without “going out in the sun?” We don’t have subways in Florida.
What about UVA? The SPF is designed to rate protection against UVB—the burning rays. And for years, only UVB was vilified for causing cancer—by causing Thymine bases in DNA to cross link. Well, now UVA, able to penetrate glass (think about driving) may cause cancer too, by penetrating deeper into the skin and generating free radicals.
Well, the FDA will soon be adding a four-star rating system to reflect UVA protection. Until then, the words “Broad Spectrum” let you know that the product offers some UVA protection. And, it is essentially impossible to have an SPF of 30+ without some UVA protection.
So, go to the beach…or shopping. But use SPF 30+ 15-30 minutes before sun exposure. Reapply either 15-30 minutes after arrival or after any activities (swimming, sweating.) Reapply again before 2 hours have elapsed. And don’t forget the broad-brimmed hat. And remember to use sunscreen under the swimsuit—don’t stop at the fabric edges. That’s how you don’t get burned using sunscreen.

Diane Cantrell, M.D.