Sunscreen Myths and Facts: What patients are asking Patricia Lucey, MD, FAAD Inova Melanoma and Skin Cancer Center
I have no financial or personal disclosures.
Top 10 Sunscreen Myths Questions/Concerns asked by real patients. 1. The sun is natural, I thought a little is good for you. 2. I only need sunscreen if I m going to be outside. 3. I heard sunscreen doesn t even prevent against melanoma. 4. I shouldn t wear sunscreen because I m Vitamin D deficient. 5. Tanning provides a protective base tan. 6. If you have darker skin, you don t need sunscreen. 7. I swear I l wear sunscreen, but I still get burned or tanned. 8. Every time I wear sunscreen, I get a reaction. 9. I heard sunscreen is full of harmful chemicals. 10. I heard sunscreen is bad for the environment.
Myth #1 The sun is natural, so a little is good for you Ultraviolet radiation (UVR) in sunlight is the most ubiquitous environmental carcinogen, and consequences of UVR exposure include MM and NMSC These skin cancers have reached epidemic proportions and their associated morbidity and mortality are substantial. An estimated 87,110 new cases of invasive MM will be diagnosed in the U.S.in 2017 (NOT MMis) An estimated 9,730 people will die of melanoma in 2017 (1 death every 54 mins) Melanoma accounts for <1% of skin cancer cases, but the vast majority of skin cancer deaths The vast majority of melanomas are caused by the sun On average, a person s risk for melanoma doubles if he or she has had more than five sunburns The most recognizable cutaneous effect by acute UVR is the sunburn. Other effects of UVR include: tanning, freckles and increased numbers of new moles Long-term effect of UVR are manifested as photoaging (sunspots, wrinkles, easy bruisability) and actinic neoplasia Actinic neoplasia is defined as pre-cancerous actinic keratoses (AK), and skin cancers squamous cell carcinomas (SCC) and basal cell carcinomas (BCC).
Ultraviolet Radiation (UVR) UVR is divided into UVA, UVB and UVC Ultraviolet C (UVC; 270-290 nm) filtered by ozone Ultraviolet B (UVB; 290-320) shorter wavelength, reaches only epidermis Ultraviolet A (UVA; 320-400 nm) longer wavelength, reaches dermis While both UVA and UVB exhibit biological, they differ in many respects. effects and are known to induce skin cancers
UVA vs. UVB Induces an immediate erythema that lasts for 2-3 days Primarily involved in the pathogenesis of photoaging, actinic neoplasia and melanoma Over 95% of UVR from sunlight reaching the basal proliferating keratinocytes and melanocytes is UVA, which makes UVA quite relevant for both MM and MNSC Produces reactive oxygen species that then induce DNA damage Exerts untoward effects on skin by accelerating the aging process and is immunosuppressive Induces erythema from several hours and peaks after 6-24 hours Primarily causes sunburn and actinic neoplasia, and has historically been felt to play a role in the majority of AK and cutaneous SCC Causes direct DNA damage by forming their classic UVB DNA signature mutations (cyclobutanepyrimidine dimers [CPDs]) which are found in AK and SCC Serves as both an initiator and accelerator of carcinogenesis as UVB is immunosuppressive
UVR and Melanoma Both UVB and UVA can generate melanocytic hyperplasia/melanomas in various animal model systems. Epidemiological studies have provided considerable evidence linking tanning bed use (mostly UVA) with melanoma. Given that the immune system plays an important role in melanoma recognition and potential removal, the immunosuppression induced by both UVB and UVA likely play important roles in allowing melanocytic tumors to progress. Hence, both UVB and UVA have been implicated in melanoma formation and protective measures must take into account both spectra to be effective.
Myth #2 I only need sunscreen if I m going to be outside Many people believe that sunscreen is only necessary when their entire body is exposed to sunlight, such as when at the pool or swimming in the ocean. Ultraviolet light is still harmful to exposed skin, no matter how much of it is exposed. Some people also believe that sunscreen is not necessary on cloudy days because the sun does not feel as strong as usual. The truth is that anytime the body is exposed to light from the sun, it is exposed to UV rays, even if it is an overcast day. The lower arms and face are common areas to leave exposed throughout the day, which may increase their risk of sun damage and skin cancer
Myth #3 I heard sunscreen doesn t even prevent against melanoma While it has been known for several decades that sunscreen use in humans is protective against actinic neoplasia (AK, BCC, SCC), it was controversial on whether or not sunscreen protected against melanoma. Some earlier studies suggested little to no benefit for sunscreen use in protecting against melanoma, and given that early sunscreens contained little UVA protection, and the latency of melanoma formation, there were confounding factors. Then a large prospective study (1,600+ adults) from Australia, spanning for more than a decade (1986-1996), DID indeed show that daily sunscreen users experienced a 50% reduction in numbers of melanomas in comparison to non-users, with a 73% decrease in invasive melanomas. Thus, broad-spectrum sunscreens containing both effective UVB and UVA filters will protect against both malignant melanoma as well as actinic neoplasia.
Myth #4 I shouldn t wear sunscreen because I m Vitamin D deficient Vitamin D is a vital nutrient for human health, and the body makes it easily through exposure to UV rays or can also be obtained from the diet Vitamin D is made in the skin from cholesterol through a chemical reaction that is dependent on sun exposure (specifically UVB radiation) Vitamin D from either dermal synthesis from sunlight or the diet is biologically inactive; activation requires enzymatic conversion (hydroxylation) in the liver and then the kidneys Sunscreen, however, blocks UV rays, so, in theory, using sunscreen 100 percent of the time would prevent the body from absorbing vitamin D However, sunlight can penetrate clothing, sunscreens lose their effectiveness over time, and it is likely a person doesn t wear sunscreen every time outdoors
Myth #5 Tanning provides a protective base tan Some people believe that they should use tanning beds to get a quick tan before summer comes, or before exposing themselves to a lot of sun, such as when on vacation. Tanning beds use high concentrations of UVA light to darken the skin quickly, whereas the sun includes both UVA and UVB light. Exposing the body to high levels of UVA light from a tanning bed creates a temporary tan that will do very little to protect the skin from sun exposure and sunburns caused by UVB light. Acute intermittent sun exposure is more associated with MM Chronic cumulative sun exposure is more associated with NMSC Every tan is still a sign of DNA damage!
Myth #6 If you have darker skin, you don t need sunscreen People with dark skin are still at risk of sunburn and skin damage. Taking precautions, such as wearing sunscreen, is always recommended regardless of skin color. Melanin DOES act to diffuse UVB rays and may protect again sunburns to some extent, thus some people believe that those with more melanin in their skin do not need to use sunscreen. While people with darker skin are more protected from the sun, they should still use a full spectrum sunscreen. UVA damage is not blocked by melanin in the same way and can lead to premature skin aging and wrinkles. Melanin will also not protect the skin from extreme sun exposure, such as spending long hours in the sun unprotected. People with darker skin are also not protected against skin cancer. **One study noted that skin cancer survival rates were lowest in people with darker skin, including African- Americans, Asian-Americans, Native Americans, and Pacific Islanders.
Myth #7 I swear I l wear sunscreen, but I still get burnt/tan SPF = MED protected skin / MED unprotected skin (SPF 15 = 150 minutes/10 minutes) SPF is a measure of how well a sunscreen will protect skin from UVB rays, NOT UVA! SPF is a rough estimate that depends on skin type, intensity of sunlight and amount of sunscreen used The declared SPF is based on the use of a sunscreen layer of 2mg/cm 2 of skin, or about one ounce for full body coverage (However, only around a quarter (0.5mg/cm 2 ) is applied by most users! ***Barriers for effective sunscreen protection are many and include: Non-use, forgetting, inconvenience, applying suboptimal amounts, not re-applying, not being truly water proof/resistant, not using on a daily basis, using sprays instead of creams, the stability of the filters/ inactivation by sunlight
Myth #8 Every time I wear sunscreen, I get a reaction Types of sunscreens: UV filters generally block sunlight in one of two mechanisms: Physical sunscreens: Contain active mineral ingredients which work by sitting on top of the skin to deflect and scatter damaging UV rays away from the skin AKA: sunblock, physical blockers or inorganic sunscreens Types: titanium dioxide and zinc oxide Chemical sunscreens: Contain organic (carbon-based) compounds which create a chemical reaction and work by absorbing UV rays, changing them into heat, then releasing that heat from the skin AKA: chemical absorbers or organic sunscreens Types: Oxybenzone, Octinoxate (Octylmethoxycinnamate), Homosalate, Helioplex, Octisalate, Octocrylene, Avobenzone, Mexoryl SX and XL, benzophenone-4, benzophenone-8, menthyl anthranilate, PABA, Padimate O, and trolamine salicylate, Tinosorb S, Uvinul T 150, Uvinul A Plus
Physical sunscreens vs. Chemical Sunscreens Starts protecting immediately upon application, no wait needed Lasts longer when in direct UV light Less likely to cause a stinging irritation on the skin, making it better for sensitive skin Better for those with heatactivated skin (like those with rosacea and redness) since it deflects the heat and energy given off by the sun away from the skin Less likely to clog pores Protects against both UVA and UVB rays and is naturally broad spectrum* Thicker, whiter, harder to rub in Requires about 20 minutes after application before it begins to work Breaks down quickly in UV light, so reapplication must be more frequent Increased chance of redness for rosacea-prone skin types Increased chance of irritation and stinging, and the higher the SPF, the higher the risk of irritation for sensitive skin types May clog the pores for oily skin types Can cause stinging if it drips into the eyes from sweat Higher risk of allergy/photoallergy Thinner, more spreadable, not as white Toxicity concerns?!?!
Myth #9 I heard sunscreen is full of harmful chemicals Toxicity concerns for sunscreens: Will the chemical penetrate skin and reach living tissues? Will it disrupt the hormone system? Can it affect the reproductive and thyroid systems and, in the case of fetal or childhood exposure, permanently alter reproductive development or behavior? What if it is inhaled? (spray sunscreen) Environmental Working Group (EWG) Ratings: Oxybenzone (8)*, Octinoxate (6): higher toxicity concerns, hormone-like activity (acts like estrogen in the body; alters sperm production in animals; associated with endometriosis in women), found in breast milk, high rates of skin allergy Homosalate (4), Octisalate (3), Octocrylene (3): moderate toxicity Avobenzone (2): best UVA protection*, limited skin penetration, no hormone disruption, relatively high rates of skin allergy Mexoryl SX (2): low penetration, no hormone disruption, rare allergy Zinc oxide (2), titanium dioxide (2): no skin penetration, no hormone disruption, no risk of skin allergy
Oxybenzone: fact vs fiction Facts: Oxybenzone has been available for over 40 years It is widely used in sunscreens and other consumer products in the US The CDC has estimated the prevalence of oxybenzone exposure in the general US population to be 96.8% In the past few years, oxybenzone has received increasing attention as a potentially harmful compound Initial concerns arose when a report demonstrated systemic absorption of oxybenzone in humans at a rate of 1% to 2% after topical application, and higher rates of cutaneous absorption in human subjects have been observed. The potential for biological effects, however, were first published in a study by Schlumpf et al demonstrating uterotropic effects in immature rats after oral administration of oxybenzone (it should be noted that the estrogenic effect detected was less than 1 million-fold of estradiol, the positive control used) Nonetheless, this study served as the basis for considerable public concern
Oxybenzone: Facts vs Fiction Per a research letter published in the Archives of Dermatology (Wang SQ, Burnett ME, Lim HW. Safety of Oxybenzone: Putting Numbers Into Perspective. Arch Dermatol. 2011;147(7):865 866): The levels of exposure this study reached to produce health problems in the rats were extremely high. Their results indicates that both the application regimens and time periods required to obtain systemic levels of oxybenzone equivalent per unit of body mass are essentially unattainable, even those who use sunscreen regularly and liberally. Most relevant is that in a human study, oxybenzone did not demonstrate significant endocrine disruption, even with application of a formulation containing 10% oxybenzone The researchers noted that after 40 years of oxybenzone being an ingredient in sunscreens, there are no published studies that demonstrate toxic effects in humans caused by absorbed oxybenzone.
Myth #10 I heard sunscreen is bad for the environment. According to the study published in 2016 in the Archives of Environmental Contamination and Toxicology: Between 6,000 and 14,000 tons of sunscreen lotion winds up in coral reef areas each year, much of which contains oxybenzone. Oxybenzone can be fatal to baby coral and damaging to adults in high concentrations Oxybenzone also thought to be toxic to algae, sea urchins, fish and mammals (affecting embryonic development and hormone disruption?) The mining and processing of minerals for mineral -based sunscreens is both resource-intensive and environmentally taxing and by creating titanium dioxide, large amounts of iron sulfate waste or smaller amounts of the more hazardous iron chloride waste can be created When zinc oxide and titanium dioxide nanoparticles wash off skin, they enter the environment, with unknown effects and possible implications of nanoparticle pollution for the environment have not been sufficiently assessed Concern with spray/aerosol sunscreen causing air pollution
Conclusions: Ultraviolet radiation (UVR) in sunlight is the most ubiquitous environmental carcinogen. Skin cancers resulting from UVR exposure have reached epidemic proportions in the United States. Both UVA and UVB have been shown to cause melanoma, BCC, SCC, AK and photoaging and broad spectrum sunscreens can help prevent these. Physical and chemical sunscreens have both many advantages and disadvantages Some sunscreens are safer while others pose higher risk for allergy, irritation and possible toxicity concerns Many myths about sunscreen cause barriers to effective sunscreen use and thus we as health care providers need to educate our patients on the facts of sunscreen risks, benefits and proper use
References: Faurschou A, Wulf HC. The relation between sun protection factor and amount of suncreen applied in vivo. Br J Dermatol.2007 Apr;156(4):716-9. Schalka S, dos Reis VM, Cucé LC. The influence of the amount of sunscreen applied and its sun protection factor (SPF): evaluation of two sunscreens including the same ingredients at different concentrations. Photodermatol Photoimmunol Photomed.2009 Aug;25(4):175-80. Bodekaer M, Faurschou A, Philipsen PA, Wulf HC. Sun protection factor persistence during a day with physical activity and bathing. Photodermatol Photoimmunol Photomed.2008 Dec;24(6):296-300. Schalka S, Reis VM. Sun protection factor: meaning and controversies. An Bras Dermatol. 2011 May-Jun;86(3):507-15. Cole C, Appa Y Ou-Yang H. A broad spectrum high-spf photostable sunscreen with a high UVA- PF can protect against cellular damage at high UV exposure doses. Photodermatol Photoimmunol Photomed. 2014 Aug;30(4):212-9. Wang SQ, Burnett ME, Lim HW. Safety of Oxybenzone: Putting Numbers Into Perspective. Arch Dermatol. 2011;147(7):865 866. doi:10.1001/archdermatol.2011.173 Downs, C.A., Kramarsky-Winter, E., Segal, R. et al. Arch Environ Contam Toxicol (2016) 70: 265. https://doi.org/10.1007/s00244-015-0227-7 https://www.uptodate.com/contents/vitamin-d-deficiency-beyond-the-basics http://www.ewg.org/2015sunscreen/report/the-trouble-with-sunscreen-chemicals/ http://www.skincancer.org/prevention/sun-protection
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