Sunscreen: Your Skin’s Bodyguard

Mojgan Hosseinipour, D.O.
Edited by Paul M. Graham, D.O.

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Spring is upon us and summer is near. With longer days, many of us will embrace outdoor activities and the sun for the matter. Although there are some benefits to a modest amount of sun exposure, unprotected exposure to ultraviolet (UV) radiation has been proven to be a major factor in the development of skin cancer. The best skin cancer prevention strategy aims at minimizing sun exposure. This includes wearing sun-protective clothing and wide-brimmed hats, seeking shade when UV exposure is most intense, between the hours of 10 am to 2 pm, and the routine use of sunscreen.

Sunscreens are classified as organic versus inorganic filters based on their mechanism of action. Organic filters, chemical sunscreens, are translucent when applied. They exert their protective effects by absorbing UV energy and transforming it to and releasing it as heat. Inorganic filters or physical sunscreens are commonly referred to as sunblock because they are composed of minerals that absorb, reflect, and scatter UV light. These agents appear opaque when applied and block a higher percentage of light compared to organic sunscreens. Zinc oxide and titanium dioxide are the only FDA-approved inorganic filters. You may remember these as the thick, white sunscreen your uncle put on his nose. Nowadays, these sunscreens are thinner and more transparent, providing consumers with a more cosmetically acceptable appearance.

UV radiation has a broad spectrum ranging from 40-400nm, with UVA ranging from 320-400nm and UVB from 290-320nm. UVB causes direct damage to the skin resulting in short term effects such as sunburns and pigmentation (freckles). UVA causes indirect, long-term effects on the skin such as photoaging. Photoaging includes fine and deep wrinkles, laxity of the skin, irregular pigmentation, rough patches that may be pre-cancerous, and even development of certain skin cancers.

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Collagen is a major structural protein in the skin that gives the skin a smooth, plump appearance. UVA causes degradation of collagen resulting in decreased skin elasticity and increased skin wrinkling. The best sunscreen agents contain broad spectrum filters that achieve protective coverage against both UVA and UVB and the resultant short and long-term effects from collective sun exposure. The importance of sunscreens aims at protecting the skin and minimizing the cumulative damage caused by sun exposure over time. The effectiveness of sunscreens is measured through the sun protective factor (SPF). SPF is a ratio that measures the amount of UV radiation that burns protected skin versus the amount required to burn the same unprotected skin. This means a sunscreen with SPF 30 will provide 30 times the protection compared to not wearing sunscreen at all. It would take 30 times longer to sunburn. Thus, it is best to apply a liberal amount of sunscreen about 20-30 minutes before sun exposure and continue to apply it every 2-3 hours. Broad-spectrum agents are only those with SPF 15 or higher. Most dermatologists recommend using at least SPF 30. There is a lack of evidence to support that sunscreens with SPF greater than 50 have any advantage that those containing SPF 50 or below.

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There are many health benefits of using sunscreens, most importantly, prevention of skin cancer. As a added benefit, sunscreens will also protect against photoaging. Many patients ask what they can do to prevent wrinkles. I remember a lecture given by a dermatologist I once trained under, in which she stated the only proven way is proper use of sun protection! The image that always comes to mind is of this gentleman, a delivery truck driver, with significant wrinkling of the left side of his face, compared to a smoother texture on the right.

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A picture is worth a thousand words for sure. The significance of wearing facial sunscreen daily is quite evident from this one photograph. In addition, there is medical literature with evidence supporting that sunscreens are the most effective at preventing photoaging. The product I am using currently using is Replenix UltiMATTE Perfection 50+ tinted physical sunscreen. It has broad-spectrum UVA and UVB coverage with active ingredient zinc oxide 16.2%. This BB cream applies very smoothly to the skin, similar to the feel of makeup primer. It provides a sheer touch of color for all skin tones helping to minimize any imperfections. It is a great product because it doubles as both a daily sunscreen and a tinted moisturizer.

Although we have many resources to help with sun protection, there continues to be an increased incidence of skin cancer. Researchers postulate that higher protection has led to longer sun exposure from a false impression of safety in the sun. Therefore it is important to emphasize avoiding unnecessary sun exposure regardless of sun protective measures. In addition, many fail to apply sunscreen properly and regularly. Most people often only apply one-fourth to one-half the amount of sunscreen necessary for adequate protection. Proper sunscreen application includes 1 teaspoon to the face, head and neck, 1 teaspoon to each arm, 1 teaspoon for the chest and 1 teaspoon for the back, and 2 teaspoons to each leg. Apply sunscreens liberally to all exposed skin at least 15-30 minutes before sun exposure. These recommendations are similar for children, with an emphasis on reduced sun exposure and the use of sunscreens as a corresponding measure.

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In summary, practice photoprotective measures daily to prevent skin cancer as well as reduce the risk of photoaging. Sunscreen should always be used in combination with other sun-protective measures, including photoprotective clothing and use of wide-brimmed hats. Avoid the sun between the time of 10 am to 2 pm when UV radiation is most intense. Broad-spectrum sunscreens with SPF 30 to 50 is ideal. Sunscreens should be applied uniformly to all exposed skin and should always be reapplied regularly to maintain effectiveness. My motto is everything in moderation so have fun and stay protected.

References:

  1. Jansen R., Osterwalder U., Wang S.Q., Burnett M., Lim H.W. Photoprotection: Part II. Sunscreen: Development, efficacy, and controversies. J Am Acad Dermatol. 2013;69.
  2. Lautenschlager S., Wulf H. C. & Pittelkow M. R. Photoprotection. Lancet. 2007;370:528–537.
  3. Latha M. S., Martis J., Shobha V., Sham Shinde R., Bangera S., Krishnankutty B., et al. Sunscreening agents: a review. J Clin Aesthet Dermatol. 2013;6:16–26.
  4. Mancebo SE, Hu JY, Wang SQ. Sunscreens: a review of health benefits regulations, and controversies. Dermatol Clin. 2014;32:427–438.

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