Conference Coverage

Be ready for patient questions on sunscreen safety, SPF choice


 

EXPERT ANALYSIS FROM ODAC 2020

– Dermatologists should be well versed in addressing common concerns that patients, family members, and the media have about photoprotection, Adam Friedman, MD, advised at the ODAC Dermatology, Aesthetic, & Surgical Conference.

Dr. Adam Friedman, professor and interim chief of dermatology, George Washington University, Washington, DC

Dr. Adam Friedman

“Know the controversies. Be armed and ready when these patients come to your office with questions,” Dr. Friedman, professor and interim chair of dermatology at George Washington University, Washington, said in an interview at the meeting, where he presented on issues related to photoprotection.

Which SPF to choose and the impact of sunscreen on vitamin D are among the issues patients may be asking about.

Sunscreen SPFs above 50 don’t technically provide a “meaningful” increase in ultraviolet protection, given that this value relates to filtering about 98% of UVB, but they still can provide some benefit, which has to do with real-world human error, Dr. Friedman said.

“Most people don’t use sunscreens the right way,” meaning they don’t apply enough to achieve the SPF listed, he added in the interview. “A higher SPF is meaningful, because if they apply less [sunscreen], they actually still are in that safety window,” with the higher SPF sunscreen. (The American Academy of Dermatology recommends an SPF of 30 or higher.) Several studies have shown that a SPF of 70 or 100 is superior to 50, likely because of this “dilutional” effect.

Patients may have concerns about the effects of sunscreen on vitamin D production, the environment, and hair loss, and whether they have endocrine disrupting effects, added Dr. Friedman, who is also the medical director of the meeting.

Inhibition of cutaneous vitamin D synthesis after using sunscreen can vary, based on whether a person has properly applied sunscreen, the season, latitude, and an individual’s age and obesity level. Patients with low vitamin D levels can use a vitamin D supplement to achieve sufficient levels, and patients concerned about the impact of sunscreen and vitamin D can be advised to take 600 IU of vitamin D3 a day, according to Dr. Friedman. Some studies have suggested that UVB exposure and risk of certain cancers are inversely correlated, implicating cutaneous vitamin D synthesis (J Clin Transl Endocrinol. 2014 Oct 5;1[4]:179-86). But correlation does not equal causation, he pointed out.

Other concerns stem from the potential for oxybenzone, a UVA/UVB filter in more than 70% of sunscreens, to act as an endocrine disruptor in people and whether it is potentially damaging the environment. The data driving these concerns “stem from the bench, not the real world,” Dr. Friedman said. While topical application of oxybenzone can result in systemic absorption, and even though it’s been detected in waters that are heavily populated or where people go on vacation, there is no evidence demonstrating toxicity to humans or the coral reefs. “At least the information we have to date says they don’t,” he added.

In a randomized clinical trial recently published in JAMA, Food and Drug Administration investigators found that systemic skin absorption with geometric mean plasma concentrations greater than 0.5 ng/mL with six active ingredients in sunscreen that were tested, including oxybenzone (JAMA. 2020;323[3]:256-7). The study was part of an FDA proposed rule requesting additional information on sunscreen ingredients; the plasma concentrations exceeded the level at which further safety studies could potentially be waived.

The study, Dr. Friedman said, “only demonstrated the ability to detect these UV filters at very small concentrations in the blood. They have yet to show any meaningful biologic correlation to these findings.”

For those patients who prefer not to use chemical filters, Dr. Friedman suggests recommending mineral-based sunscreens, of which he said micro- and nanoparticulate formulations offer the best cosmesis by sitting more evenly on the skin, being more amenable to thinner and less-lipophilic vehicles, and limiting visible light scattering (thereby limiting the unsightly white appearance) – while maintaining UV scattering efficacy. However, controversy has emerged as there are past studies that posit the theoretical danger of nanoparticles in sunscreens, given their potential to penetrate the skin and enter cells.

But continually emerging evidence has shown that commercially available nanosunscreens are safe, with no toxicity even at the cellular level when applied to the skin in sunscreen or in cosmetics. “All evidence to date suggests they do not do this,” Dr. Friedman said, noting that, in Europe, the European Commission’s Scientific Committee on Consumer Safety has stated that nanoparticles below a concentration of 25% in sunscreens is safe, “just don’t put them in aerosolized forms.”

Lastly, while some recent studies have detected titanium dioxide on the hair shafts of patients with and without frontal fibrosing alopecia, Dr. Friedman noted more evidence is needed before recommending that these patients avoid using sunscreen (Br J Dermatol. 2019 Jul;181[1]:216-7). “Correlation does not mean causation, and the current dogma is that there’s no connection between these two,” he commented.

Dr. Friedman reported consulting and advisory board relationships with numerous companies; he also reported speaking for Regeneron, Abbvie, and Dermira, and receiving grants with Pfizer and DF Pharma.

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