By Dr. Kathryn Barlow

Some of the most common questions patients have are about sun protection, skin cancer prevention and sunscreen use. There are many controversies about the safety of sunscreen and how this relates to the prevention of skin cancer. Here are several of the most common myths out there about sunscreen and sun exposure, and the science that debunks them.

Myth #1 – Sunscreen causes cancer.

Recently, several articles have claimed certain sunscreens like retinyl palmitate and oxybenzone can actually cause cancer or are harmful in other ways. To date, there is no scientific proof of these claims. The Food and Drug Administration has several safety regulations in place that monitor sunscreen, including safety data. UV radiation is the most common cause of skin cancer, although genetic influences, smoking, and other factors play a smaller role.

Myth #2 – Sunscreen causes early puberty and disrupts hormones in other ways.

This is another scientifically unfounded claim, and is based on questionable science that has not been verified by leading experts in the field of photomedicine. What we do know is that 90% of non-melanoma skin cancers (basal cell and squamous cell carcinomas), and about 65% of melanomas are associated with UV exposure on unprotected skin. Still not convinced? Then opt for sunscreens containing only zinc oxide or titanium dioxide. These physical blockers stay on the skin’s surface and deflect the UV radiation.

Myth #3 – It’s good to get a base tan.

Tan skin is damaged skin. Your skin cells that make skin pigment (called melanin) are called melanocytes. The melanocytes make more melanin in response to UV radiation for the sole purpose of protecting your skin cell’s genetic material (DNA) from becoming damaged and transforming from normal skin cells into cancer cells. Not to mention that most people get their “base tan” from indoor tanning beds which is one of the absolute worst things for your skin when it comes to premature aging and skin cancer risk. There are no safe tanning beds and never a reason to get into one.

Myth #4  – You won’t get enough Vitamin D if you use sunscreen all the time.

Vitamin D is very important for many aspects of our health, including bone growth and formation, as well as supporting a healthy immune system. However, the UVB rays (ultraviolet B) that produce vitamin D are also the very same wavelengths that cause the most skin cancer risk. Furthermore, our bodies are not able to absorb enough Vitamin D from sun alone to meet our needs. Normal vitamin D levels can easily be achieved through dietary intake and vitamin supplements. There is no compelling reason to expose yourself to a known cancer-causing agent (UV radiation) to get your vitamin D.  If someone said you could get Vitamin C from a cigarette, most people would drink some orange juice rather than take up smoking. Getting vitamin D from the sun makes about as much sense.

Myth #5 – The higher the SPF, the longer I’m protected.

The SPF, or sun protection factor, measures a sunscreen’s ability to block UVB. No sunscreen blocks 100% of these rays. For example, a sunscreen with an SPF of 15 filters out about 93% of UVB, SPF 30 filters about 97%, and SPF 50 filters out about 98% of UVB rays. All sunscreens must be reapplied liberally at a minimum of every 2 hours. The amount of sunscreen you use also matters. Adults typically require 1 ounce (enough to fill a shot glass!) per full body application. Also, make sure your sunscreen is “broad spectrum,” meaning it protects against both UVB and UVA rays.

Myth #6 – Sunscreen in my makeup is enough.

Wearing daily sunscreen on the face and neck is one of the very best ways to help prevent the daily sun damage that accumulates over the years to cause premature aging and skin cancer. The SPF rating is determined by a complex system of testing. A very specific amount of the makeup must be applied to reach the stated SPF, and most do not apply nearly enough to achieve this. Also, unless you are applying makeup to your neck and exposed upper chest area, these vital areas are unprotected. Using a light facial moisturizer of SPF 30 to the face, neck and chest every day is an easy way to protect them. Any extra SPF in the makeup is icing on the cake.

Myth #7 – Applying sunscreen once a day is enough.

No sunscreen, regardless of SPF number or strength, should be expected to work longer than 2 hours. The duration of protection is even less when sweating heavily or with water exposure. Reapplying is key to maintain protection. However, sunscreen alone is only part of the equation. Seeking shade, wearing protective clothing such as UV filtering shirts, wide-brimmed hats and sunglasses are also absolutely key to protecting your skin.

Now that you know the truth about sunscreen, what else can you do to limit damage when exposed to the sun? Here are some top tips:

• When you shop for sunscreen, try to find physical sunscreens (containing zinc or titanium oxide) rather than chemical sunscreens (most common sunscreens on the market are chemical, so it might take a little searching to find the best sunscreen for you). While it’s true physical sunscreens like zinc don’t absorb and usually leave a visible white film, there are clear zinc sunscreens available now. Here’s a good primer on physical vs. chemical sunscreens.
• Sunglasses with total UV protection can help protect your sensitive eyes, but also the skin around your eyes, which is thin and delicate. The better you protect this skin, the less you’ll notice “crow’s feet” and other visible signs of aging around your eyes.
• Protective clothing includes thick-woven (i.e. not sheer or lightweight) garments, but companies also make clothing specifically designed to block harmful UV radiation. These clothes are often light and comfortable for warm weather wear. One such brand of protective clothing is Coolibar.
• Keep an eye on your skin with regular self-exams. Make note of any moles or spots so you can monitor them for changes over time. This is a great guide to self-exams. But don’t rely on self-exams alone. See a dermatologist annually for a full body exam, too.

Sources: Skin Cancer Foundation, American Academy of Dermatology

Dr. Kathryn Barlow practices dermatology at Dermatology Consultants’ Eagan office. She specializes in general and cosmetic dermatology, minor dermatologic surgery, chemical peels, laser treatments and skin cancer. She has been named Mpls/St.Paul Magazine’s Top Docs – Rising Star for multiple years and has also been acknowledged by Minnesota Monthly as one of the area’s Best Doctors for Women.