Image source: Ifccenter.com

There are certain rumors about skin care that sound so logical, people assume they must be true.  Unfortunately, sometimes the right answer is the one that combats common sense!  Here are five of the most common myths about summer skin care I have recently heard:

1.  SPF 100 means 100% protection.

Errrt, wrong!  An SPF of 100 means that the sunscreen blocks 99.0% of UV rays.  And yes, that means an SPF of 200 is not only possible, but also would theoretically only block 99.5% of UV rays.  How did I get these numbers?  The amount of UVB an SPF is effective at blocking can be estimated using the following algorithm from dermatologist Dr. Rachel Herschenfeld: SPF means that  1/(SPF number) of rays goes through.  That means that SPF 30 allows 1/30 UVB rays, or 3.3% through, blocking about 96.6% of UVB rays, and SPF 50 allows 1/50 UVB rays, or 2.0% through, blocking about 98.0% of UVB rays.  According to Dr. Leslie Baumann, über-derm and author of Cosmetic Dermatology, the Sun Protection Factor (SPF) commonly listed on products refers to the amount of UVB protection, measured by the time it takes for a person without sunscreen versus a person with sunscreen to show a erythemal skin reaction (i.e., to show redness).

2.  A base tan protects you from future sun damage.

Yes, it is true that darker-skinned women naturally have a slight SPF built-in to their skin (as if Halle Berry and Iman weren’t enough to make me jealous already, *sighs*).   However, women who are lighter-skinned should not get a “base tan” to prevent future damage.  For one, you will incur free radical and structural damage while trying to achieve the build-up of melanin that yields the bit of sun protection.  And two, let’s not forget that everyone — of all skin tones — still needs sun protection: “[Melanin build-up provides an umbrella of sun protection], but the umbrella is porous – you’re still getting DNA damage, which can lead to wrinkles and skin cancer,” says NYC dermatologist Dr. Doris Day in the June issue of Allure.  In other words, everyone needs sunscreen, and while dark skin naturally provides a bit of beneficial SPF, tanning lighter skin to get there isn’t benefiting you in the long run.

3.  Self-tanner saves you from free radical damage.

Yes and no on this one.  Yes, there is nothing proven to naturally age your faster UV light, which does pretty much everything from depleting collagen levels to inducing free radical production at monstrous levels.  And if you use self-tanner and stay out of the sun as a result, then you are saving your skin. However, if you use self-tanner and then go out into the sun, you could be causing more damage:  According to a 2007 study published in Germany (and cited in Allure), for 24 hours after applying a self-tanner, the skin is more susceptible to free-radical damage once being exposed to the sun.

In other words, best case scenario:  avoid self-tanner, wear sunscreen, and avoid the sun between 10-4 P.M. except for 15 minutes/week (for adequate vitamin D production).  Next best scenario:  use self-tanner, wear sunscreen, and avoid the sun between 10-4 P.M. except for 15 minutes/week.  Worst case scenario:  use self-tanner, don’t wear sunscreen, and go out into the sun.  Eeeeek!

4.  “If my powder contains SPF, that’s enough protection.”

Oh dear.  If you want to know how much SPF you are really getting from a product, divide the SPF number by 14, according to Dr. Leslie Baumann, über-dermatologist from the University of Miami.  According to Baumann, scientists estimate the SPF of a facial powder assuming 1200 mg of product is used with each application, but the average woman only applies 85 mg of powder at a time, 14 times less than the estimated amount.  In other words, if you want adequate sun protection, wear a moisturizer or sunscreen with SPF under your powder, even if your powder contains sunscreen.

5.  SPF = UPF.

UPF, the rating system for sun protective clothing, has been getting a lot of press recently because sun protective clothing is currently popular and – dare I say it – increasingly stylish.  However, unlike SPF, which quantifies only UVB protection, UPF is a number that incorporates both UVA and UVB (broad-spectrum) protection.

In general, according to Baumann’s Cosmetic Dermatology textbook, a UPF of 10 equals protection of about SPF 30, so a UPF of 50 equals protection of about SPF 150 (i.e., lets 1/150 rays through, providing 99.25% protection).  Pretty cool, huh? 

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In short, rumors were made to be about Hollywood celebrity scandals, not your skin.  Let’s put an end to these 5 skin care myths, shall we? 

Let me know your thoughts!  After all, until June 19, 2008, every comment on FutureDerm.com counts as 1 entry in the $500 skin care giveaway from Skinmedix.com!