, according to Steven Q. Wang, MD, director of dermatologic surgery and dermatology, Memorial Sloan-Kettering Cancer Center, Basking Ridge, N.J.
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Although sunscreens are regulated as an OTC drug under the Food and Drug Administration, concerns persist about the safety of sunscreen active ingredients, including avobenzone, oxybenzone, and octocrylene, Dr. Wang said in a virtual presentation at MedscapeLive’s annual Las Vegas Dermatology Seminar.
In 2019, the FDA proposed a rule that requested additional information on sunscreen ingredients. In response, researchers examined six active ingredients used in sunscreen products. The preliminary results were published in JAMA Dermatology in 2019, with a follow-up study published in 2020 . The studies examined the effect of sunscreen application on plasma concentration as a sign of absorption of sunscreen active ingredients.
High absorption
Overall, the maximum level of blood concentration went above the 0.5 ng/mL threshold for waiving nonclinical toxicology studies for all six ingredients. However, the studies had several key limitations, Dr. Wang pointed out. “The maximum usage condition applied in these studies was unrealistic,” he said. “Most people when they use a sunscreen don’t reapply and don’t use enough,” he said.
Also, just because an ingredient is absorbed into the bloodstream does not mean it is toxic or harmful to humans, he said. Sunscreens have been used for 5 or 6 decades with almost zero reports of systemic toxicity, he observed.
The conclusions from the studies were that the FDA wanted additional research, but “they do not indicate that individuals should refrain from using sunscreen as a way to protect themselves from skin cancer,” Dr. Wang emphasized.
Congress passed the CARES Act in March 2020 to provide financial relief for individuals affected by the novel coronavirus, COVID-19. “Within that act, there is a provision to reform modernized U.S. regulatory framework on OTC drug reviews,” which will add confusion to the development of a comprehensive monograph about sunscreen because the regulatory process will change, he said.
In the meantime, confusion will likely increase among patients, who may, among other strategies, attempt to make their own sunscreen products at home, as evidenced by videos of individuals making their own products that have had thousands of views, said Dr. Wang. However, these products have no UV protection, he said.
For current sunscreen products, manufacturers are likely to focus on titanium dioxide and zinc oxide products, which fall into the GRASE I category for active ingredients recognized as safe and effective. More research is needed on homosalate, avobenzone, octisalate, and octocrylene, which are currently in the GRASE III category, meaning the data are insufficient to make statements about safety, he said.
Vitamin D concerns
Another sunscreen concern is that use will block healthy vitamin D production, Dr. Wang said. Vitamin D enters the body in two ways, either through food or through the skin, and the latter requires UVB exposure, he explained. “If you started using a sunscreen with SPF 15 that blocks 93% of UVB, you can essentially shut down vitamin D production in the skin,” but that is in the laboratory setting, he said. What happens in reality is different, as people use much less than in a lab setting, and many people put on a small amount of sunscreen and then spend more time in the sun, thereby increasing exposure, Dr. Wang noted.
For example, a study published in 1988 showed that long-term sunscreen users had levels of vitamin D that were less than 50% of those seen in non–sunscreen users. However, another study published in 1995 showed that serum vitamin D levels were not significantly different between users of an SPF 17 sunscreen and a placebo over a 7-month period.