Hooman Khorasani, MD

Guest blog written by John Zade, current research fellow under Hooman Khorasani, MD, the Chief of the Division of Dermatologic & Cosmetic Surgery at The Mount Sinai Hospital and Assistant Clinical Professor of Dermatology at the Icahn School of Medicine at Mount Sinai.

With Melanoma awareness month just ending and summer just starting, it’s a perfect time to talk about how to protect yourself from the sun. Although sun damage doesn’t seem to affect us immediately, over the period of your life it’s one of the leading causes of skin cancer. If you think this doesn’t apply to you, think again: one in five Americans will develop skin cancer within their lifetime (Robinson, 2005). Aside from increasing skin cancer risk, sun damage is a known cause of premature skin aging, deep wrinkles, and uneven skin tones. The good news is that we can protect ourselves from the sun’s damage by following a few simple steps.

Step number one: get a good sunscreen and use it often! With so many sunscreens in the market today this is no easy task. I’m going to try and address some of the bigger questions on sunscreen use and when/how to apply it:

What is SPF and which number should I use?

To answer the first question, SPF stands for Sun Protection Factor and is a way to measure what degree a sunscreen will protect you from sun damage. This is measured by taking the time is takes you to burn with a sunscreen on divided by the time it would take you to burn without a sunscreen on. In other words, it’s how many times longer you can stay in the sun without getting burned. Most dermatologists recommend that the SPF level be greater than 30.

What else should I look for in a sunscreen?

When choosing a sunscreen one important thing to make sure of is that it is “broad-spectrum,” meaning that it protects you from UVA and UVB radiation. UVA light is less talked about but these rays penetrate deeper into the skin and are the main cause for sun-induced pre-mature aging and wrinkling.

Which sunscreen should I use if I have sensitive skin?

If you have sensitive skin or are prone to breaking out, the physical sunscreens are the best option for you. These products usually contain Zinc Oxide or Titanium Dioxide and act as a barrier to protect you from the sun. They are broad-spectrum, less irritating, and less likely to clog pores than chemical sunscreens. The downside to physical blockers is that they can leave a white-ish cast on your skin. Luckily the newer physical blockers are less likely to cause this white-ish coloring and there are even tinted sunscreens for different skin-tones.

When should I use my sunscreen?

You should make a morning routine of applying your sunscreen and use it everyday. If you are going to be out in the sun, then you should be using sunscreen. Once integrated into your morning skincare routine (which I will make another blog post about soon!) you will be covered for the beginning of the day. Most dermatologists recommend reapplying sunscreen every 2-3 hours as the day goes by. If you are going to be swimming, then you should be reapplying sunscreen when you get out of the water or every 15-30 minutes, whichever is sooner. It is important to remember that no sunscreen is “water-proof,” no matter what the catchy advertisements might tell you.

What are the commonly missed spots?

We’re bound to miss a few spots and there are some spots that are more commonly missed than others. Any area that will be exposed to sun should be covered, including your ears, upper chest, top and bottom of your feet (the bottoms are exposed when lying down), and your neck. Your scalp is also exposed to the sun and is a tricky area to try and apply sunscreen to– a protective hat may be the best option for those of you who don’t want to put sunscreen in your hair.

 How much sunscreen should I use?

A good rule of thumb for the amount of sunscreen you need to cover your exposed body areas is 1 ounce. That’s about equal to one shot glass full of sunscreen.

Are the products in sunscreens safe and will it cause vitamin D deficiency?

With the new movement of keeping everything organic, gluten-free, anti-vaccinated and “safe,” sunscreen ingredients have come under the spotlight. Unfortunately, I have to burst the bubble on this theory, as the human studies testing ingredients in sunscreens have not shown any significant toxicity (Gasparro, Mitchnick, & Nash, 1998). The one area that we have insufficient data on is spray sunscreens, which can be inhaled and may impact the lungs. If you want to play it safe, lotion or cream sunscreens are the way to go.

Another common question is if sunscreen will block the beneficial effects from the sun, such as getting enough vitamin D. Vitamin D deficiency is not fully understood and it seems to be the new fad diagnosis in medicine. Even in people who are highly sun exposed, like Hawaiian surfers, there are still cases of vitamin D deficiency (Hollis, Wagner, Drezner, & Binkley, 2007). So although in theory sunscreen could block your body’s ability to create sun-induced vitamin D, this does not seem to hold up in the real world setting (Norval & Wulf, 2009).

Once I put on my sunscreen can I go tanning?

Definitely not! Your goal in the sun should never be to get a tan; whenever you think of tan skin you should think of damaged skin. It is a misconception that a base tan can help protect you from the sun. As the dermatologist saying goes, “there is no such thing as a safe tan.”

How early can I put my child on sunscreen?

It’s generally accepted that children greater than 6 months can join the rest of the adult population in wearing sunscreen. You should not, however, start lathering your baby with sunscreen right away. Just to be safe, put a small amount of your chosen sunscreen on a tiny area of your baby’s skin and leave it on for 30 minutes. As long as there’s no reaction (such as redness or swelling), your baby should tolerate the ingredients in the sunscreen. Even though we can safely apply sunscreen to our babies, you should still try to limit their sun exposure and use as much protective clothing as possible. For your infants younger than 6 months, it is generally recommended to stick to protective clothing for sun damage control.

What else should I know?

Although this post mainly addressed sunscreens, there are many other steps you can take to protect yourself from the sun. This includes wearing protective clothing and trying to limit your sun exposure as much as possible (generally avoiding direct sunlight between 10 am and 2pm). Sun radiation is a known carcinogen and it needs to be addressed as seriously as other known cancer causing agents. Although you may not notice the benefits of incorporating sun protection into your daily routine immediately, your future, younger-looking, cancer-free self will thank you.

References

Gasparro, F. P., Mitchnick, M., & Nash, J. F. (1998). A review of sunscreen safety and efficacy. Photochem Photobiol, 68(3), 243-256.

Hollis, B. W., Wagner, C. L., Drezner, M. K., & Binkley, N. C. (2007). Circulating vitamin D3 and 25-hydroxyvitamin D in humans: An important tool to define adequate nutritional vitamin D status. J Steroid Biochem Mol Biol, 103(3-5), 631-634. doi:10.1016/j.jsbmb.2006.12.066

Norval, M., & Wulf, H. C. (2009). Does chronic sunscreen use reduce vitamin D production to insufficient levels? Br J Dermatol, 161(4), 732-736. doi:10.1111/j.1365-2133.2009.09332.x

Robinson, J. K. (2005). Sun exposure, sun protection, and vitamin D. JAMA, 294(12), 1541-1543.