Sunscreen is critical in preventing skin cancer. UVB rays cause DNA pyrimidine dimer formation, mutations and
photocarcinogenesis. UVA rays contribute to tanning and photoaging. The latter (the vanity factor, as I like to call it), may be the most compelling argument to patients when providing sun protection education. You may encounter common misconceptions regarding sunscreen. Here is the truth:
Myth #1: When it’s cloudy, I don’t need to wear sunscreen.
Even in the winter, I still enthusiastically encourage sunscreen use in my patients! Why? Even with cloud cover, UVB rays still pass through the clouds.
Myth #2: SPF 15 is all that is needed and any higher SPF provides no added benefit.
SPF is measured using a thick layer of sunscreen (2mg/cm2). True application is closer to 0.5-1mg/cm2 lowering the effective SPF. So in actuality, patients are getting less SPF, probably less than half. Thus, I usually recommend minimum SPF of 30.
Myth #3: Makeup with SPF is sufficient sunscreen
Makeup these days often include SPF, which is great. But most have SPF 15. Again, I encourage at least SPF 30 for my patients. You should look for higher SPF in makeup or have them layer their sunscreen under their makeup for sufficient protection.
Myth #4: The best sunscreen is the one with the highest SPF
I have many patients who tell me they use SPF 100 or higher. The reality is that the added benefit from higher SPF actually plateaus as you get higher in number. SPF 15 filters 94% of UVB rays. SPF 30 filters 97%. Any higher than SPF 30 is the law of diminishing returns. For this reason, the new FDA regulations prohibit sunscreen makers from labeling their sunscreens higher than SPF 50+.
Myth #5: The sun is necessary for Vitamin D, and therefore sunscreen is dangerous
Clearly Vitamin D is important, but exposure to UVB rays is only one of the ways to meet daily Vitamin D requirements. Because sunscreen decreases skin cancer risk, I recommend a daily dose of 1000IU of Vitamin D3 from diet or supplementation especially for patients who are vigilant about sunscreen, reside in northern latitudes, or are obese, elderly, housebound or photosensitive. Given the benefits of sunscreen, I encourage getting your Vitamin D from food or supplementation. Vitamin D3 is better absorbed and is what is produced in the skin.
Myth #6: For swimming, one application of waterproof sunscreen is the best safeguard
There is no such thing as waterproof sunscreen! In fact, one of the new FDA regulations is that sunscreen makers can no longer label their sunscreen as “waterproof.” Sunscreens can now be labeled “water-resistant” instead. Sunscreen does wash off in the pool and even with sweat. I recommend reapplication after swimming, sweating, toweling off and every 2 hours.
Myth #7: The best way to apply sunscreen is to apply it every morning
Again, I would emphasize reapplication. Sunscreen wears off after only 2 hours! So if patients are applying before work, they are no protected as they leave for lunch or on their drive home.
Myth #8: Microsized zinc has dangerous systemic side effects
Microfine and nanosized zinc do not penetrate the stratum corneum, and therefore do not enter your bloodstream. Zinc is inert and nontoxic.
Myth#9: Sunscreen is toxic
It is true that several chemical sunscreens such as oxybenzone, Octinoxate and others are absorbed into the bloodstream and found in the urine. There are no studies that show there are negative effects from this occurrence. However, if you have a concern, stick with the physical blockers: zinc and titanium. These do not penetrate the stratum corneum.
Myth #10: Sunscreen causes skin cancer
This myth started with a few studies that showed that people who wore sunscreen had a false sense of security, stayed out longer in the sun, and had increased skin cancer rates. Also some patients use sunscreen as tanning aids. These patients are at higher risk for skin cancer. Another explanation is that melanoma can be inherited and is not always prevented with sunscreen use.
I hope this cheat sheet provide quick ways to educate yourself regarding sunscreen use all year round. Other important ways to avoid UV damage include covering up with broad-rim hats, sunglasses, long sleeves, and pants. I also encourage you to avoid midday sun between 10am and 4pm and to find shade whenever they can.
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