In summer, the sun is a near-constant companion in many parts of the world. But we know that the sun can be our adversary – particularly the ultraviolet radiation emanating from it. Ultraviolet light is used as phototherapy, in the treatment of conditions including jaundice, psoriasis, and cutaneous T-cell lymphoma. But in honor of UV Safety Awareness Month, we focus here on UV exposure that is environmental and not therapeutic in nature, and how best to achieve protection from harmful UV rays. Use of tanning beds is one dangerous source of ultraviolet radiation, but exposure to them is avoidable via behavioral and lifestyle changes. For other types of exposure, there are fortunately a multitude of products available for protection.
That ultraviolet radiation awareness has increased dramatically in recent years is generally a positive change, but where do consumers go to get informed about UV protection? One prominent result in Google searches is a resource from the Environmental Working Group. EWG is an activist nonprofit focused on chemicals used in agriculture and cosmetics, as well as pollutants in drinking water. The EWG has been compiling an annual review of sunscreens since 2008. Its methodology includes assigning numerical ratings to sunscreens based on their “safety.” The EcoWell, a website dedicated to combating misinformation in the cosmetics industry, has expressed some doubts about the EWG’s methodology, which is disclosed at length on their website, but is not easily evaluated by non-experts. EWG includes the following statement in their page on methodology: “Most people [believe] the government oversees the safety of their cosmetics and other personal care items. Not so.” (EWG, n.d.) Even a non-expert can understand that this position stakes a specific claim, and thus the information is not coming from an unbiased source. Additionally, EWG offers companies an opportunity to become “verified” on their website, which in part involves a financial transaction, and means that verified products appear before others in the database. This information is inconclusive, but doesn’t inspire confidence in a nonprofit that claims to be organized in the public interest.
While consumers might be grateful for a source that is easily accessible, it is very important to understand that the EWG’s findings are not evidence-based. According to Dr. Adewole Adamson, MD, MPP, speaking to Dermatology Times this month, “None of [the EWG’s] data is actually based on any information that involves actual clinical or actual patient use in the real world. I do not think that patients should change their behavior related to putting on whatever sunscreen it is that they use based on this data.” (Andrus, 2024)
Another important thing to understand about sunscreens on the market in the United States, as opposed to those sold in Europe or Asia, is that in the U.S. sunscreen is regulated as though it were a drug. In Europe and Asia, sunscreen is regulated as a cosmetic. Because drug regulation is a more rigorous process, the U.S. has seen fewer sunscreen filters approved for use than in other countries. As a result, Americans have fewer and more limited product choices for protection.
One recent evidence-based guide to sunscreens is this 2023 review on photoprotection, published in the Archives of Dermatological Research. Photoprotection is the practice of minimizing damage to skin and eyes from damage that ranges in severity from sunburn to photoaging to the development of malignant neoplasms. There are two types of ultraviolet radiation, UVA and UVB. UVB exposure is at its highest level in summer, while UVA exposure is more constant throughout the year and leads to carcinogenesis. Sunscreens which are labeled “broad spectrum” primarily protect from UVB, but also protect from UVA. In addition to UV, 50% of ultraviolet radiation comes from visible light, which causes other types of skin conditions, or else can trigger flares of chronic conditions. While UV radiation is absorbed or scattered, visible light is reflected.
The authors of the review state that people “should be encouraged to avoid outdoor activities during peak sun hours, seek shade, apply sunscreen, wear sun protective clothing, and sunglasses.” (McDonald et al, 2023) Avoiding exposure, then, is our first line of protection. But that isn’t practical for most people, especially those who want to participate in summer activities outdoors. It is important to learn more about the different types of sunscreen products and their pros and cons. Sun Protection Factor, or SPF, is a common measure of the effectiveness of sunscreens.
On an FDA website explaining SPF, we learn that the number associated with a sunscreen product’s SPF is commonly misconstrued as a measure of protection based on the amount of time one is exposed to the sun. This is incorrect because solar intensity differs by time of day. In fact, SPF denotes the amount of UV radiation required to produce sunburn on protected versus unprotected skin. (FDA, 2017) One study cited in the review from Archives of Dermatological Research found that SPF 85 provided significantly more protection against sunburn than did SPF 50. A product with a higher SPF may help compensate for an insufficient amount of sunscreen being applied. Frequency of reapplication of sunscreen is important, particularly when there is water exposure or perspiration.
The two main types of sunscreen are chemical, or organic sunscreens, which represent 75% of products currently on the market, and include chemical filters which absorb UVR. Physical, or inorganic sunscreens approved by the FDA include zinc oxide and titanium dioxide, which form a physical barrier to UV absorption. While chemical sunscreens are absorbed more readily on the skin, physical sunscreens are not. Tinted sunscreens contain iron oxides and synthetic mica for cosmetic purposes, in addition to other sunscreen ingredients. The authors of the review found limited evidence of the use of systemic agents protecting against UVR.
One photoprotective measure whose availability has dramatically increased in recent years is sun protective clothing. When selecting UPF (ultraviolet protection factor) clothing for sun safety, the number associated has to do with how much UVR is able to penetrate through different fabrics. However, the authors note that “UPF does not account for body surface area covered.” (McDonald et al, 2023) In general, most natural fibers provide less protection from UVR than synthetic fabrics or wool, darker colors absorb more UVR, and looser clothing provides more protection from UVR. Clothing marked UPF50+ is considered an excellent source of protection.
Now that we’ve discussed protecting the body, what about our heads and eyes? Wearing sunglasses helps decrease UVR damage to the skin around the eyes, the lens, and the cornea. Wearing a hat protects our vulnerable scalps, with wider brimmed hats providing optimal protection for both head and neck.
The review goes on to discuss evidence on adverse effects from photoprotection, including a comparison of evidence on superficial cutaneous absorption versus systemic absorption, concluding that despite the presence of sunscreen compounds in plasma, there simply is no evidence to date that sunscreen ingredients cause any harm to humans – a conclusion in stark contrast to those drawn by the EWG.
We only have the one skin we’re born with, so learning how best to protect it from UVR is time well spent!
References
Andrus, E. (2024/07/05). Addressing Sunscreen Safety. Dermatology Times, 45(7), 6. https://www.dermatologytimes.com/view/addressing-sunscreen-safety-a-review-of-ewg-s-2024-guide-to-sunscreens
Center for Drug Evaluation and Research. (n.d.). Sun Protection Factor (SPF). U.S. Food and Drug Administration. https://www.fda.gov/about-fda/center-drug-evaluation-and-research-cder/sun-protection-factor-spf#:~:text=SPF%20is%20a%20measure%20of,produce%20sunburn%20on%20unprotected%20skin Accesssed on July 11, 2024
Environmental Working Group. About | Skin Deep | Cosmetics Database. Environmental Working Group. https://www.ewg.org/skindeep/learn_more/about/ Accessed on July 12, 2024
McDonald, K. A., Lytvyn, Y., Mufti, A., Chan, A. W., & Rosen, C. F. (2023). Review on photoprotection: a clinician's guide to the ingredients, characteristics, adverse effects, and disease-specific benefits of chemical and physical sunscreen compounds. Archives of dermatological research, 315(4), 735–749. https://doi.org/10.1007/s00403-022-02483-4
