Posted on March 27th, 2009 by
Indoor tanning is a $5 billion–per–year industry that’s marketed itself as safe and even beneficial. The truth may not be so sunny.
By Kari Bohlke, ScD
Each year in the United States, an estimated 28 million people visit an indoor tanning facility, with a majority of visits made by women and teenage girls. In a survey of White adolescents (13 to 19 years old), 37 percent of the girls and 11 percent of the boys reported having used a tanning bed at least once. The bad news is that tanning beds—like the sun—expose the skin to ultraviolet (UV) radiation, and a growing body of research indicates that indoor tanners have an increased risk of skin cancer. “Indoor tanning represents one of the most striking examples of preventable skin cancer,” explains David Fisher, MD, PhD, a medical oncologist and chair of the Department of Dermatology at Massachusetts General Hospital.
Not surprisingly, the indoor tanning industry has dismissed the skin cancer research while choosing instead to focus on the benefits of vitamin D. Vitamin D—which is produced by the skin in response to ultraviolet B (UVB) radiation or obtained through diet—may indeed provide important health benefits, but before you (or your teenagers) head to the tanning salon, be aware of three key points:
In this article the term indoor tanning refers to exposure to artificial ultraviolet radiation through tanning beds or sunlamps. It does not refer to sunless self-tanning products such as sprays and lotions (see sidebar for more information about these products).
An Overview of Ultraviolet Radiation
Ultraviolet radiation is a type of electromagnetic radiation—energy moving at the speed of light in the form of particles or waves. Other familiar types of electromagnetic radiation are radio waves, microwaves, visible light, and X-rays. These different types of radiation are classified based on their energy content, and together they form the electromagnetic spectrum. On the electromagnetic spectrum, UV radiation falls between visible light and X-rays, carrying more energy than visible light but less energy than X-rays.
Ultraviolet radiation is often divided into three types: UVA, UVB, and UVC. UVA has the longest wavelength and the least energy of the three; UVC has the shortest wavelength and the most energy. Although the sun emits all three types of ultraviolet radiation, only UVA and UVB reach the surface of the earth (UVC and some UVB are blocked by the ozone layer). UVA and UVB are also the types of ultraviolet radiation emitted by most tanning beds.
UVB is the cause of most sunburns and has long been recognized as carcinogenic. UVA—which penetrates more deeply into the skin—was initially thought to be relatively safe. Now, however, it’s recognized that both types of UV radiation are likely to contribute to skin cancer.4, Ultraviolet radiation also contributes to premature aging of the skin.
Indoor Tanning and Skin Cancer
More than 1 million new cases of skin cancer are diagnosed in the United States each year. Skin cancer is often divided into two broad categories: melanoma and nonmelanoma. Nonmelanoma skin cancer refers to several different types, but the most common are basal cell carcinoma and squamous cell carcinoma. Basal cell and squamous cell carcinomas tend to be less deadly than melanoma, but they are cancers and can behave unpredictably.
“Squamous cell carcinoma, which has a rock-solid connection to UV, actually does cause cancer deaths,” notes Dr. Fisher. “It has a much lower risk of metastasizing [spreading to other parts of the body] than melanoma, but when it does, it is essentially as lethal as melanoma.” Skin cancer can also be disfiguring when it occurs on cosmetically sensitive areas such as the face.
Analyses of skin cancer trends have identified a disturbing increase among young adults in the United States, particularly young women. Between 1973 and 2004, the frequency of melanoma more than doubled among women 15 to 39 years of age; melanoma rates also increased among men in this age range but to a lesser extent. The researchers note: “The recent increase in incidence among young women parallels reported trends in exposure to [ultraviolet radiation], the primary environmental cause of melanoma.”13 Studies have also reported an increasing occurrence of basal cell and squamous cell carcinomas.
The strongest evidence for a link between indoor tanning and melanoma is found among individuals who were first exposed to indoor tanning at a young age. In a combined analysis of previously published studies, individuals who had their first exposure to indoor tanning before the age of 35 were 75 percent more likely to develop melanoma than individuals who had no exposure to indoor tanning. In addition, exposure to indoor tanning was linked with a more than twofold-increased risk of squamous cell carcinoma.
With regard to the risks of indoor tanning, Dr. Fisher notes that the evidence is compelling for melanoma and unequivocal for squamous cell carcinoma. “I don’t think that even the indoor tanning industry would argue with the evidence for squamous cell carcinoma,” he says. “But what they do ignore is the fact that there are deaths from metastatic squamous cell carcinoma.”
What About Vitamin D?
Vitamin D is produced in the skin in response to UVB and can also be obtained from food or dietary supplements. The potential health benefits of vitamin D are described in another article in this issue of Women&Cancer.
Tanning beds that emit UVB do stimulate vitamin D production by the skin, but as Dr. Fisher explains there are two strong arguments against indoor tanning as a source of vitamin D: “Number one, there’s another way to get vitamin D—a pill—that yields exactly the same chemical; it’s indistinguishable as a vitamin and does not come with a carcinogen. Number two, the dose of UV that would be needed to replenish blood levels to a healthy level is very unpredictable. It depends on the intensity of the UV, it depends on how much of a tan you have, and it depends on how low your vitamin D was to begin with. The proper way to replete and maintain a healthy level of vitamin D in your bloodstream is to have your blood level checked by a doctor once during your routine blood check. Find out if you need extra vitamin D to boost you to a healthy level.” If you do, a daily vitamin D supplement can help you achieve and maintain a healthy level of vitamin D without increasing your risk of skin cancer or premature aging of the skin. Your doctor can help you decide whether you should consider vitamin D testing or supplementation.
A Clear Message
The messages from credible medical and scientific organizations such as the American Academy of Dermatology and the World Health Organization are clear and consistent: avoid tanning beds, be sun-smart, and get your vitamin D safely. Avoidance of tanning beds may be particularly important for young people, who appear to have the greatest increase in risk of skin cancer as a result of indoor tanning.
“From a policy perspective, and certainly from an education perspective, we need to do something about this,” says Dr. Fisher, drawing a parallel between where we are currently with indoor tanning and where we were 60 years ago with cigarettes. “As an oncologist, it’s such a sad thing.”
Sunless Tanning Products
In contrast to sunlamps and tanning beds, sunless self-tanning sprays or lotions have not been linked with an increased risk of skin cancer. These products use a chemical known as dihydroxyacetone (DHA) to darken the surface of the skin. A few points are important when using these products :
Ideally, of course, we wouldn’t feel compelled to use any tanning product (other than a broad-spectrum sunscreen).
Can Indoor Tanning Be Addictive?
Only a few small studies have addressed this question, but the answer may be yes. In one of the most intriguing studies, researchers found that treatment with the drug naltrexone (an opioid antagonist used to treat alcohol and narcotic addition) produced withdrawal-like symptoms in four of eight frequent tanners. Withdrawal-like symptoms were not experienced by infrequent tanners treated with naltrexone. In addition, when comparing two identically appearing tanning beds—one of which emitted UV radiation and one of which did not—treatment with naltrexone reduced the extent to which frequent tanners preferred the UV-emitting bed.
. Demko CA, Borawski EA, Debanne SM, Cooper KD, Stange KC. Use of indoor tanning facilities by white adolescents in the United States. Archives of Pediatrics and Adolescent Medicine. 2003;157(9):854-60.
. FAQs. Indoor Tanning Association Web site. Available at: http://www.theita.com/indoor/faq.cfm. Accessed December 28, 2008.
. Report on Carcinogens, Eleventh Edition; U.S. Department of Health and Human Services, Public Health Service, National Toxicology Program. Available at: http://ntp.niehs.nih.gov/ntp/roc/eleventh/intro.pdf. Accessed December 18, 2008.
. Be Sun Smart. American Academy of Dermatology Web site. Available at: http://www.aad.org/public/sun/smart.html. Accessed December 28, 2008.
. Global Disease Burden from Solar Ultraviolet Radiation. World Health Organization Web site. Available at: http://www.who.int/mediacentre/factsheets/fs305/en/index.html. Accessed December 28, 2008.
. Sun Safety Action Steps. U.S. Environmental Protection Agency Web site. Available at: http://www.epa.gov/sunwise/actionsteps.html. Accessed December 28, 2008.
. Ultraviolet (UV) Radiation. U.S. Food and Drug Administration Web site. Available at: http://www.fda.gov/cdrh/tanning/uvradiation.html. Accessed December 28, 2008.
. Agar NS, Halliday GM, Barnetson RS, Ananthaswamy HN, Wheeler M, Jones AM. The basal layer in human squamous tumors harbors more UVA and UVB fingerprint mutations: A role for UVA in human skin carcinogenesis. Proceedings of the National Academy of Sciences. 2004;101(14):4954-59.
. Cancer Facts & Figures 2008. American Cancer Society Web site. Available at: http://www.cancer.org/docroot/STT/stt_0.asp. Accessed December 28, 2008.
. Christenson LJ, Borrowman TA, Vachon CM, et al. Incidence of basal cell and squamous cell carcinomas in a population younger than 40 years. Journal of the American Medical Association. 2005;294(6):681-90.
. Exposure to Artificial UV Radiation and Skin Cancer. International Agency for Research on Cancer Web site. Available at: http://www.iarc.fr/en/Publications/PDFs-online/IARC-Working-Group-Reports/Exposure-to-Artificial-UV-Radiation-and-Skin-Cancer. Accessed December 28, 2008.
. Tanning Products. U.S. Food and Drug Administration Web site. Available at: http://www.fda.gov/cdrh/tanning/tanningproducts.html. Accessed December 28, 2008.
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