Sunscreen controversies confuse consumers

July 6, 2020

Patients may be afraid to use a sunscreen considering reports describing the potential for a variety of adverse effects. Physicians should seek a strong understanding of the evidence to discuss benefits and safety with patients and encourage proper sunscreen use.

Media reports about sunscreen use, including its potential harms, can lead consumers to wonder whether they should be using sunscreens for photoprotection and which product to choose.

Adam Friedman, M.D., says dermatologists need to be knowledgeable about the controversies and be prepared to answer patients’ questions with information that will reinforce the importance of sunscreen use.

“People from certain special interest groups and industries are disseminating claims and reports associating sunscreens with a range of deleterious effects. When the data are carefully examined; however, it is clear there is no valid foundation for the existing concerns,” says Dr. Friedman, professor and interim chair of dermatology, The George Washington University School of Medicine & Health Sciences, Washington, D.C.

“What we do know for certain based on very strong evidence, however, is that exposure to ultraviolet (UV) radiation causes skin cancer and skin aging, and sunscreens used appropriately can prevent those harmful effects.”

Setting the record straight

One of the major controversies surrounding sunscreen use is that it can interfere with natural Vitamin D synthesis. Studies on this topic have generated conflicting results, partly because of methodological differences. An important consideration in extrapolating the results is that most people do not properly apply sunscreen. Therefore, cutaneous Vitamin D synthesis will not be totally inhibited in sunscreen users in the real-world.

The bottom line, however, is that the concern represents a moot point because adequate systemic Vitamin D levels can be achieved in the absence of cutaneous synthesis through foods and dietary supplements.

“Patients should be told that they are able to get Vitamin D in safe ways without making the sacrifice of exposing themselves to the adverse effects of the sun by avoiding sunscreen use,” Dr. Friedman says.

Oxybenzone exposure is another common consumer concern, and the issues relate both to its purported activity as an endocrine disruptor and environmental impact on ocean coral. Dr. Friedman points out that oxybenzone has many positive attributes that explain why it is a commonly used sunscreen ingredient.

“Oxybenzone is inexpensive, easy to formulate, and provides very effective broad-spectrum protection against UVA and UVB radiation,” he says.

He acknowledged that it has received some negative attention as being one of the most common photo-allergens among UV filters.

“The risk, however, is relevant to a small number of people and is not a reason to limit its widespread use.” Dr. Friedman says.

Claims that oxybenzone acts as an endocrine disruptor are based on data from preclinical research using in vitro cell cultures and animals fed oxybenzone. In these experiments, the concentrations of oxybenzone causing adverse effects far exceed the level that can be achieved following external sunscreen use.

“Researchers addressing the safety of topically applied oxybenzone calculated that a person would need to apply sunscreen at the density recommended by the U.S. Food and Drug Administration of 2 mg/cm2 to 100% of the body surface area daily for 35 years to reach the systemic level reported to be harmful,” Dr. Friedman says.

“To date, there have been no clinically significant negative effects of oxybenzone in humans.”

Concern that oxybenzone represents an environmental toxin causing coral bleaching has led some states and municipalities to ban the sale of oxybenzone-containing sunscreens. Evidence linking oxybenzone to coral bleaching, however, comes from an artificial model conducted with conditions that do not replicate actual marine reef ecosystems. Furthermore, the adverse effect occurred at a concentration of oxybenzone that exceeds its level in the ocean, even in waters off highly vacationed coasts.

“This is another situation where we need to look at the numbers in the real-world versus the lab and consider the confounders. There are numerous environmental factors that contribute to coral bleaching, and areas where there is maximal coral bleaching do not correspond with human habitation,” Dr. Friedman says.

“On the other hand, oxybenzone is the most effective sunscreen ingredient we have that covers UVA. States that are banning oxybenzone have overstepped in limiting its availability considering the current state of science,” Dr. Friedman says.

He adds, “Patients can be told that hypothetical environmental concerns alone should not interfere with sun protection, but if they are worried, they can use a mineral-based sunscreen instead.”

Mineral-based sunscreen concerns

Dermatologists may find themselves fielding a growing number of questions about risk of frontal fibrosing alopecia (FFA) with facial sunscreen use. This concern may emerge based on recent studies that reported finding titanium species on the hair shaft of patients with FFA.

“Remember that correlation does not equal causation,” Dr. Friedman says.

“Authors of a recent review article on this topic concluded that there is insufficient evidence to establish a direct causal relationship between sunscreen and FFA.1 Therefore, the medical community should take pause before advising sunscreen avoidance in patients with FFA.”

Concerns about the safety of nanosized particles in mineral-based sunscreens were more prevalent in the past but have generally diminished after accumulating evidence showed that the particles do not penetrate or harm the skin.

“The materials may be detrimental if inhaled or ingested, which argues against using mineral-based sunscreens in aerosolized formulations. There is not any problem, however, with cream or lotion preparations,” Dr. Friedman says.

Picking the right SPF

The wide range of SPF values found in available sunscreens is another source of confusion for consumers who wonder what they should choose. While the official recommendation from the American Academy of Dermatology advises selecting a product with an SPF of at least 30, patients may wonder if higher is better.

As it relates to protection against UVB radiation, sunscreens provide only incrementally greater protection as the SPF value increases above 30, assuming the product is properly used. The average consumer, however, applies only one-fourth to one-half of the amount needed to impart the labeled SPF value. Choosing a sunscreen with an SPF higher than 30 has utility to compensate for underuse.

“Regardless of the SPF value, sunscreens cost the same and feel the same on the skin, but it may be worthwhile to recommend choosing a higher SPF product knowing that it will be more likely to give the patient proper protection in the setting of expected use,” Dr. Friedman says.

Disclosure:
Dr. Friedman serves as a consultant for Aveeno, Cerave, and La Roche-Posay, and Neutrogena.

Reference:
1 Robinson G, Mcmichael A, Wang SQ, Lim HW. Sunscreen and frontal fibrosing alopecia: A review. J Am Acad Dermatol. 2020;82(3):723-728.

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