BY DR. MATT MAHLBERG
COLORADO CENTER FOR DERMATOLOGY & SKIN SURGERY
Dr. Matt Mahlberg is a board-certified dermatologist and fellowship-trained Mohs surgeon who is Medical Director of the Colorado Center for Dermatology & Skin Surgery in Greenwood Village. His monthly column “Skin Insights” offers helpful educational tips to optimize the skin’s health. His practice can be found at Orchard and Quebec and www.coloradodermatology.com or via phone at (303) 761-0906.
Recently, the news has been filled with reports about a ban on sunscreens in Hawaii. While these headlines have caught a lot of attention and raised questions about the sunscreen safety, there are many misconceptions that exist about sunscreens that deserve clarification.
First, it is helpful to understand that there are two different categories of sunscreens: physical and chemical. Physical sunscreens contain mineral ingredients such as zinc oxide or titanium dioxide and work by sitting on top of the skin and reflecting harmful UV rays. Chemical sunscreens are organic (carbon-based) compounds such as avobenzone, octocrylene, and oxybenzone that absorb UV radiation and convert it into heat before it can harm our skin’s DNA. In the United States, there are only 17 FDA-approved chemical or physical sunscreen ingredients, giving a very limited number of options compared to Europe and Canada.
Misconceptions about sunscreens often come from incomplete information or information from animal data that is inappropriately extrapolated to humans. One such example involves the long-available zinc oxide. Many of us can remember rubbing the thick white paste across our nose to provide sun protection. Fortunately, manufacturers have created ‘micronized’ zinc oxide which provides the same protection but doesn’t leave the clown-like appearance. Some have raised concern that the small sunscreen particles, called nanoparticles, might be so small that they would be absorbed into our bodies and cause harm. However, numerous studies have found that these sunscreens do not pass the skin barrier in meaningful amounts.
Another misconception about sunscreen promulgated was that oxybenzone, a UVB blocking chemical sunscreen, caused hormone disruption in humans. This idea was based on a study in which huge amounts of oxybenzone were fed to rats and those rats demonstrated uterine growth. To reach an equivalent amount of oxybenzone exposure in humans, one would have to apply sunscreen over every inch of the body every day for 70 years. No measurable effects have been demonstrated in humans. Nonetheless, out of an abundance of caution, I generally recommend zinc- or titanium-based sunscreen for pregnant women.
Recent news about deleterious effects on coral reefs has further cast doubt on the use of oxybenzone. A single study in 2015 suggested that oxybenzone may play a role in leaching nutrients from coral and bleaching it white. While the Hawaii Medical Association hoped that the issue would be studied further because peer-reviewed research had not demonstrated this effect as measured concentrations in the water were far below the necessary levels to cause coral bleaching. Nevertheless, the Hawaii legislature issued a oxybenzone and octinoxate that will take effect in 2021, and sunscreen manufacturers have taken note — more oxybenzone-free sunscreens are likely on the way. With all of the environmental impact the coral reefs are suffering from multiple factors, this is assuredly a good thing.
While these controversies exist, we certainly know that photoprotection is an important way to prevent skin cancer and photoaging and that sunscreens can be one of many ways to provide this protection. At the same time, manufacturers of sunscreens need to continue developing new and safe products and dermatologists need to continue advocating for the FDA to approve more active ingredients.
If you have questions or would like to discuss which sunscreen ingredients might be best for you, please do not hesitate to contact us at (303) 761-0906 or www.coloradodermatology.com.
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