Controversies in Sunscreens: A Practical Approach

Abstract

At least 1 in 5 people will be diagnosed with skin cancer in their lifetime, and the annual incidence of skin cancer in the United States approaches over 3 million, which is higher than breast, lung, prostate and colon cancer combined.1Stern RS Prevalence of a history of skin cancer in 2007: results of an incidence-based model.Arch Dermatol. 2010; 146: 279-282Crossref PubMed Scopus (274) Google Scholar Ultraviolet (UV) radiation is a known environmental carcinogen, and sun exposure is the most critical modifiable risk factor for skin cancer.2D'Orazio J Jarrett S Amaro-Ortiz A Scott T UV radiation and the skin.Int J Mol Sci. 2013; 14: 12222-12248Crossref PubMed Scopus (892) Google Scholar Randomized controlled trials support the use of broad-spectrum sunscreen to reduce the development of skin cancer.2D'Orazio J Jarrett S Amaro-Ortiz A Scott T UV radiation and the skin.Int J Mol Sci. 2013; 14: 12222-12248Crossref PubMed Scopus (892) Google Scholar Current recommendations from the American Academy of Dermatology (AAD) include applying water-resistant sunscreen (sun protection factor [SPF] 30 or higher) with both ultraviolet A (UVA, 320-400 nm) and ultraviolet B (UVB, 290-320 nm) protection. Despite this, potential harms of sunscreen use have raised public health concerns and may lead to non-compliance. Physicians should be familiar with common concerns regarding sunscreen application to adequately counsel their patients. We highlight 3 common patient apprehensions that have garnished media attention regarding sunscreen use and provide a practical approach for sunscreen recommendations based on the most recent published evidence.•“I'm afraid to use sunscreen because of all of the chemicals that get absorbed in my body.” Sunscreen components include inorganic and organic filters. Inorganic filters are designed to physically reflect UV photons away from the skin. Organic sunscreen filters are chemicals used to absorb UV radiation and have the potential to penetrate the skin. Common organic filters include ensulizole, octisalate, octocrylene, octinoxate, oxybenzone, and avobenzone.3Schneider SL Lim HW Review of environmental effects of oxybenzone and other sunscreen active ingredients.J Am Acad Dermatol. 2019; 80: 266-271Abstract Full Text Full Text PDF PubMed Scopus (133) Google Scholar Although limited data exists on the extent of potential systemic toxicities of sunscreen use, a recent trial conducted by the Food and Drug Administration (FDA) evaluated the systemic absorption of organic filters in 24 healthy adults over a 1-week period. Participants applied 2 mg/cm2 of sunscreen to 75% of their total body surface area 4 times a day for 4 consecutive days. The study found 4 common formulations of sunscreen had plasma concentrations higher than 0.5 ng/mL (a level at which the FDA recommends additional safety testing) after the first day of application.4Matta MK Zusterzeel R Pilli NR et al.Effect of sunscreen application under maximal use conditions on plasma concentration of sunscreen active ingredients: a randomized clinical trial.JAMA. 2019; 321: 2082-2091Crossref PubMed Scopus (159) Google Scholar A more recent FDA trial demonstrated similar results.5Matta MK Florian J Zusterzeel R et al.Effect of sunscreen application on plasma concentration of sunscreen active ingredients: a randomized clinical trial.JAMA. 2020; 323: 256-267Crossref PubMed Scopus (87) Google Scholar Despite this, data does not exist regarding clinical consequences of this level of systemic absorption, and the FDA, itself, continues to recommend the use of sunscreen for UV protection.•“I'm reluctant to use sunscreen because I don't want to become vitamin D deficient.” Vitamin D is essential for skeletal integrity. UVB converts 7-dehydrocholesterol to previtamin D3 in the skin, which then thermally isomerizes to vitamin D3, after which it is 25-hydroxylated in the liver and 1-alpha-hydroxylated in the kidney.6Neale RE Khan SR Lucas RM Waterhouse M Whiteman DC Olsen CM The effect of sunscreen on vitamin D: a review.Br J Dermatol. 2019; 181: 907-915Crossref PubMed Scopus (46) Google Scholar With increasing age, there is a decline in cutaneous production and systemic activation of vitamin D.7Holick MF Vitamin D deficiency.N Engl J Med. 2007; 357: 266-281Crossref PubMed Scopus (10276) Google Scholar However, oral supplementation of vitamin D is used as an adequate alternative source. In regard to cutaneous production of vitamin D and sunscreen use, a recent meta-analysis of 75 studies found little evidence that sunscreen (with an average SPF of 16) reduces vitamin D concentration when used in real-life settings.6Neale RE Khan SR Lucas RM Waterhouse M Whiteman DC Olsen CM The effect of sunscreen on vitamin D: a review.Br J Dermatol. 2019; 181: 907-915Crossref PubMed Scopus (46) Google Scholar Additionally, a study assessing sunscreen use at high UV-index locations found no compromise in vitamin D synthesis.8Young AR Narbutt J Harrison GI et al.Optimal sunscreen use, during a sun holiday with a very high ultraviolet index, allows vitamin D synthesis without sunburn.Br J Dermatol. 2019; 181: 1052-1062Crossref PubMed Scopus (40) Google Scholar These findings suggest that with regular sun exposure, proper use of sunscreen does not prevent vitamin D synthesis. Thus, patients’ concerns regarding vitamin D levels should not prevent their performance of sun-safe behavior. If cutaneous vitamin D production is inadequate, patients can obtain dietary vitamin D or oral supplementation, while avoiding harmful UVB exposure.•“I'm worried that using sunscreen will harm the environment.” Organic filters, such as oxybenzone, are used in a variety of cosmetic and personal products, including sunscreen, and have been identified in various water sources and fish species. Studies suggest organic filters may cause coral reef bleaching3Schneider SL Lim HW Review of environmental effects of oxybenzone and other sunscreen active ingredients.J Am Acad Dermatol. 2019; 80: 266-271Abstract Full Text Full Text PDF PubMed Scopus (133) Google Scholar are based on in vitro data with conditions that do not accurately reflect the native coral reef environment.9Sirois J Examine all available evidence before making decisions on sunscreen ingredient bans.Sci Total Environ. 2019; 674: 211-212Crossref PubMed Scopus (9) Google Scholar Data more closely modeling in vivo conditions absolving sunscreen from reef bleaching exists.10Johnsen EC. Toxicological effects of commercial sunscreens on coral reef ecosystems: new protocols for coral restoration. Available at:https://nsuworks.nova.edu/cnso_stucap/335. Accessed Feb 11, 2020.Google Scholar Other factors such as climate change, including rising ocean temperature, along with industrial runoff and sewage discharge leading to salinity, acidification, and bacterial count changes are recognized as predominant culprits in coral bleaching.9Sirois J Examine all available evidence before making decisions on sunscreen ingredient bans.Sci Total Environ. 2019; 674: 211-212Crossref PubMed Scopus (9) Google Scholar Thus, environmental effects of sunscreen use should not undermine the importance of educating patients on preventing skin cancer. With the known harmful effects of sun exposure on the development of skin cancer, photoprotection is critical. When counseling patients, however, physicians must also take into account the patients’ concerns regarding organic filter absorption, vitamin D deficiency, and environmental harms. The importance of adequate photoprotection for the prevention of skin cancer has been well established. Both the risks and benefits of sun exposure should be considered when providing recommendations about sun protection. Physicians should be familiar with sunscreen composition, proper use, and benefits while encouraging patient compliance. Counseling patients should incorporate the following general guidelines:•Seek shade when appropriate, remembering that the sun's rays are strongest between 10 am and 2 pm.•Wear protective clothing, such as a lightweight long-sleeved shirt, pants, a wide-brimmed hat, and sunglasses, when possible.•Generously apply a broad-spectrum, water-resistant sunscreen with an SPF of 30 or higher. Broad-spectrum sunscreen provides protection from both ultraviolet A and UVB rays. In regard to the aforementioned patient concerns, we find the following recommendations helpful:•For patients concerned about sunscreen systemic absorption, physicians can recommend inorganic sunscreens mainly containing zinc oxide and titanium dioxide, which are generally recognized as safe and effective (GRASE), in addition to protective clothing to limit the surface area of sunscreen application.•Physicians should continue to recommend sun-safe behavior to their patients with vitamin D deficiency, in addition to vitamin D3 supplementation.•For patients concerned about the environmental impact of sunscreen, physicians can encourage their patients to pursue methods of photoprotection to provide adequate skin protection while minimizing the, albeit, likely negligible risks of environmental harm. This includes seeking shade, wearing photoprotective clothing, and limiting sunscreen application to photo-exposed skin. Patients concerned about reef safety can be directed to “reef safe” (an unregulated classification) sunscreens free of octinoxate and oxybenzone that are based on nonmicronized zinc oxide or titanium dioxide. More information for both patients and physicians can be obtained at the American Academy of Dermatology website.Patient-specific information available at: https://www.aad.org/public/everyday-care/sun-protection/sunscreen/sunscreen-resource-centerPhysician-specific information available at: https://www.aad.org/member/advocacy/priorities/sunscreen/webinar