By Sherrif F. Ibrahim, M.D., PhD & Marc D. Brown, M.D.
Published in Dermatol Surg 2008, 34;4:460–474
The History of Tanning
Multiple religions and civilizations based their beliefs around the sun, and as history evolved, medicinal uses for sunlight developed as well. Ultraviolet radiation (UVR) has been used for centuries as treatment and prevention for many ailments, such as vitiligo, rickets, lupus vulgaris and certain cancers. The authors recognize a quotation from a 1938 edition of Ladies Home Journal stating “The sunbath is just as important as the water bath,” regarding the health of infants. From an economic standpoint, a visible suntan was originally thought to be a result of blue-collar, outdoor labor, while a very fair complexion defined high class. The first implications of a tan exemplifying a higher economic status came with the industrial revolution, as an indication of free time to sunbathe. The preoccupation with achieving a golden tan continued throughout the 20th century, despite documentation dating back to 1907 connecting UVR with skin cancer. In the last four decades this irrefutable connection has become even more apparent. The use of artificial UVR has increased substantially since the introduction of indoor tanning facilities in 1978, with the authors citing studies that estimate the existence of up to 50,000 of these establishments in the United States alone. This article effectively outlines the progression of the tanning revolution and the dangers associated with this multi-billion dollar industry.
The Basics of Tanning Science
Melanin is the protein determinant for each person’s individual skin color. Darker skin tones contain more and larger melanin-filled packets (melanosomes) than lighter skin tones, with invariable numbers of pigment-producing cells (melanocytes). The effects of UVR are numerable and include inflammation, immune dysfunction, accelerated visible aging, cancer and pigmentary alterations. A tan occurs in two stages: immediate and delayed. Immediate pigment darkening (IPD) is a result of the oxidation of existing melanin and reorganization of melanosomes, and may appear within seconds of exposure. Delayed darkening of the skin occurs three to five days post-UV absorption and involves overproduction of melanocytic components that create a parasol over the keratinocytes’ nuclei to prevent further damage.
UVR is categorized into UVA, UVB and UVC rays, depending upon wavelength; each having a different histological effect. Currently, the atmospheric ozone absorbs all of the UVC and a majority of the UVB rays emitted from the sun, resulting in the Earth’s surface exposure being composed of 95% UVA and 5% UVB radiation. UVB rays, consisting of 280-320 nanometers (nm), are considered complete carcinogens, as they are directly responsible for DNA deformities and disturb the transcription and duplication of the genetic markers. UVA radiation, composed of 320-400nm, indirectly affects DNA by being absorbed by surrounding chromophores in the skin and, through excitement, produces free radicals which then cause DNA breakage. By inducing DNA damage and interfering with the skin’s delicate cellular makeup, both UVA and UVB rays are responsible for skin cancer.
Tanning is a Response to DNA Damage
The importance of the protein p53 has been substantiated in numerous articles as a tumor suppressor due to its ability to halt the formation of abnormal cells. The article’s authors review several studies which focus on the correlation between p53 and cancer; each finding that incidences of all cancers, including skin cancer, are much higher in both humans and rodents with inactive or absent p53. To further prove the undeniable link between tanning and DNA destruction, the authors cite studies where single-stranded DNA, which mimics the effects of UVB rays, was introduced to in vivo and in vitro models, resulting in a tanning response without the presence of UVR. Many additional internal changes take place with the tanning process, including the release of melanocyte-stimulating hormone (MSH), proopiomelanocortin (POMC), melanocyte-derived autocrine cytokines, and keratinocyte-derived paracrine factors, all of which are contingent upon the p53 protein. As the histology of tanning science unfolds, the promise for advanced sun protection products that are able to replace missing or mutated skin components becomes more possible for the future, potentially reducing the risk of skin cancer by upregulating the body’s natural defenses.
UVR and Cutaneous Malignancy
The statistics linking UVR and skin cancer are staggering, with cutaneous malignancies accounting for 50% of the United State’s cancer rates. Studies cited estimate over 1,000,000 cases of basal and squamous cell carcinomas, and 60,000 cases of melanoma annually. Skin cancer incidences are on the rise, causing experts to brand it as an epidemic, as the chances of developing the potentially deadly disease have increased nearly 2,000% in the last 75 years. Non-melanoma skin cancers are undoubtedly resultant from UV exposure, with few other contributing factors to these common carcinomas. While genetic factors have been shown to contribute to the development of melanoma, and although melanoma can occur in both sun-exposed and non sun-exposed areas of the body, many studies have demonstrated an obvious correlation between UV exposure and melanoma, with up to 90% of melanomas resulting from UVR. Melanoma rates have been found to be significantly higher in equator regions of higher altitudes as a result of more intense sun exposure. Clinical trials have also proven that fair-skinned individuals are much more susceptible to malignant melanoma than darker-skinned individuals, and some believe that an individual’s tanning ability may decrease their risk for developing melanoma.
But Doesn’t a Tan Protect Me from the Sun?
A very common yet erroneous thought among chronic tanners is that the development of a baseline tan will increase the natural UV protection mechanism. The sun protection factor (SPF) received from a natural UV suntan is a minuscule SPF of two to three, and from artificial tanning bulbs, an even lower one to two SPF. Even more important is the increased likelihood of an individual with an existing tan to remain outdoors for prolonged periods of time due to their dangerous misconception, therefore increasing their risk of DNA damage and skin cancers.
Tan Now, Worry Later
Unfortunately, the negative visible and internal effects of sun-bathing and tanning bed use do not appear for years, making it difficult to detour adolescents from this dangerous practice. Several dermatological studies tie childhood sun exposure to increased risks of non-melanoma skin cancers, estimating that up to 80% of one’s lifetime UV exposure is received before 18 years of age. Another study theorizes that older males are among the highest UV recipients and are more prone to melanoma-induced death. Whether or not either study proves to be true is irrelevant and, as the authors stress, early sun protection education is key to reducing all skin cancer incidences, both early and later in life.
The Double Hit
Despite the irrefutable amount of data linking UVR and skin cancer, one million people utilize indoor tanning facilities daily, and research shows that those who use these facilities are also more likely to tan outdoors as well, thereby doubling the risk factors. Hereditary predispositions, age and natural skin tone have little effect on this decision; however, those in the habit of frequenting artificial tanning establishments are much more likely to practice other unhealthy lifestyles, such as alcohol and drug abuse, smoking and eating disorders.
Tanning Bed Use and Skin Cancer
Initial data gathered connecting tanning bed use and cutaneous malignancies lacked substantiation and were deemed inconclusive, leading to misleading marketing launched by the indoor tanning industry. More recent studies are much more sound and demonstrate the undeniable association between tanning beds and basal cell, squamous cell and melanoma skin cancers. Because the bulbs utilized in tanning beds emit the same radiation as the sun, are much closer to the recipient and vary in strength, experts suggest that artificial tanning induces even more damage than natural sun exposure. Studies estimate that 20 minutes in a tanning bed equals 2 to 3 hours of natural midday sunlight, and that indoor tanning bulbs emit up to 5 times the amount of UVR than that of the sun.
Tanning, the Government, and Powerful Lobbying
Both the Food and Drug Administration (FDA) and the Federal Trade Commission (FTC) have set certain regulations for the tanning industry, as many experts compare the connection between cancer and UVR to that of smoking and lung cancer. Currently, regulations for equipment, eye protection and misleading marketing and in some states, age specifications, are in place. Unfortunately, few establishments follow these regulations, with most showing a less than 15% compliance rating. Research shows that many indoor tanning facilities not only market unlimited tanning, but many advertise in high school newspapers. There are also groups such as the International Tanning Association (ITA) that lobby to reverse the current safety laws and irresponsibly market the supposed health benefits of indoor tanning. The authors quote several statements made including, “ensure safety, consistency, and optimal exposure (unlike the outdoors)” and “wards off a host of debilitating and sometimes deadly diseases.” It is, in part, these false statements that lead to the confusion contributing to rising skin cancer rates.
The Vitamin D Debate
Many reports have been written discussing vitamin D and its health benefits. While there is no disputing that vitamin D is essential to multiple physiological processes, there is no evidence that prolonged, unprotected sun exposure is necessary to absorb ample amounts, and the risks far outweigh any potential health benefits. Several studies show that minimal sun exposure is needed (approximately five minutes daily) and that daily sunscreen use does not interfere with required vitamin D absorption. Furthermore, adequate vitamin D levels can be achieved without any sun exposure through the consumption of fortified milk and/or dietary supplements.
Is it Possible to Be Addicted to Tanning?
It has been suggested through recent research that tanning may be habit-forming. In some cases, experts compare tanning to other common substance abuse, and research shows that the release of endorphins and sexually related melanocortins triggered by UVR may reinforce the behavior.
So Where Do We Go from Here?
As previously discussed, current regulations are minimally enforced and followed, but as clinical data builds, the previously set regulations are sure to change and several new parameters are sure to be introduced, many with harsh penalties for those who do not comply. These new laws may include, but are not limited to, education as early as preschool; new Surgeon General’s warnings; age restrictions, similar to alcohol and cigarette purchases; and many advertising regulations. The use of sunless tanning facilities is also on the rise, and is thought to be a much safer way for those who want to achieve the look of a “tan” without the danger. Sunless tanning facilities utilize dehydroxyacetone (DHA), an FDA-approved dye that safely alters the appearance of skin tone.
Conclusions
Although the sun is an unavoidable part of daily life, overexposure to UVR not only accelerates the aging process but also dramatically increases the risk of malignancy by inducing DNA mutations. Education to the public is imperative in decreasing the rising skin cancer numbers by dispelling rumors that a tan is an indicator of health and adds natural protection from the sun. As knowledge of the cellular processes of the tanning reaction are uncovered new and technologically advanced sun protection products may become available in the future. Governmental intervention of the potentially deadly indoor tanning industry and the release of public service announcements as to the numerous negative effects of intentional, natural and artificial UV exposure will also assist in decreasing dangerous consumer practices.
Reprint requests: Dr. Sherrif F. Ibrahim, Department of Dermatology, University of Rochester Medical Center, 601 Elmwood Avenue, Box 697, Rochester, NY 14642.
