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September 17, 2019

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Weekend doctor: Sunscreen

By Julie Schloemer, MD
Summer is a time of enjoying your time out in the sun. However, the number of newly diagnosed skin cancers is rising at an alarming rate. Therefore, it is important to protect your skin from Ultraviolet (UV) radiation through photoprotective clothing and proper use of sunscreen. You should always wear a sunscreen, either a chemical filter or physical blocker, with an SPF of at least 30, as well as a lip balm with SPF 15 or higher.

Sunscreen: What you need to know
The number of newly diagnosed skin cancers, including melanoma, is rising at an alarming rate. Ultraviolet (UV) radiation is a major cause of the three most common types of skin cancer – basal cell carcinoma, squamous cell carcinoma and melanoma. Both UVA radiation (which contributes to signs of aging) and UVB radiation (which causes sunburns) increase one’s risk for skin cancer. The topic of photoprotection against these deserves a moment in the spotlight, especially given recent controversies regarding the safety of sunscreen.

First and foremost, the best way to protect your skin from UV radiation is to seek shade during the peak hours of 10 a.m. to 4 p.m. and wear photoprotective clothing, including a wide-brimmed hat. Sunscreen should be considered the second line of defense.

There are two types of sunscreens: chemical filters and physical blockers. Chemical sunscreens undergo a chemical reaction with UV radiation, converting the energy into heat. Physical sunscreens physically block the absorption of UV radiation by the skin. Sunscreen products may contain a combination of a physical blocker and one or more chemical filters. Chemical filters found in sunscreens sold in the United States include: Avobenzone, oxybenzone, octyl salicylate, homosalate and octinoxate.

In general, chemical filters tend to blend in well and are more transparent. However, because heat is produced during the chemical reaction with UV rays, they should be avoided in people who have certain skin conditions exacerbated by heat, including melasma. A

lso worth mentioning, is a recent study that demonstrated the absorption of chemical sunscreens into the bloodstream after maximal application over four days.

While it is an important point to consider, studies have not shown a link between sunscreen use and adverse health effects. Some chemical filters have also been a concern in contributing to environmental pollution of the oceans and bleaching of the coral reefs.

While there are certainly many factors contributing to the problem, physical sunscreens are considered “reef-safe” and ideal for those who want to minimize the impact on the ecosystem.

The two active ingredients found in physical blockers are zinc oxide and titanium dioxide. These are often called “mineral sunscreens.” The disadvantage of physical sunscreens is the white “cast” they tend to leave on the skin, as they don’t always rub in easily. However, there are some physical sunscreens on the market that are lightly tinted, making them more cosmetically appealing and providing an additional layer of photoprotection.

As a dermatologist, I generally recommend physical sunscreens, especially for children and people with sensitive skin. The American Academy of Dermatology does not recommend the use of sunscreen in infants less than six months of age, but instead advises to keep their skin covered or in the shade when outside.

Finally, be sure to select a sunscreen with a sun protection factor (SPF) of at least 30. It should also be labeled “broad-spectrum,” indicating it protects against both UVA and UVB rays.

Don’t forget to re-apply throughout the day, especially if perspiring heavily or enjoying water activities.

Be aware that lips can get sunburned too. Apply a lip balm with SPF 15 or higher at regular intervals when outdoors.

For more information or tailored recommendations, visit your local board-certified dermatologist.