Introduction
Molecular and Cellular Effects of Tanning
Increased Risk of Melanoma and nonmelanoma Skin Cancer
‘Benefits’ of Sun Bed Tanning
References
Further Reading
Sunbeds, or tanning beds, expose individual skin to ultraviolet radiation to increase melanin production. Exposure to ultraviolet radiation from indoor tanning technology is correlated with an increased risk of Melanoma as well as other negative health consequences.
Despite these findings, the practice of indoor tanning using sunbeds across the world is prevalent.
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The World Health Organisation international agency for research on cancer (IRAC) classified ultraviolet radiation emitted from sunbeds as carcinogenic uncategorized artificial sources of ultraviolet radiation in the same carcinogenic category as tobacco and asbestos in 2009. Moreover, the Society of Behavioral Medicine issued a position statement recommending a ban on indoor tanning in young adults and children in 2014; this coincided with the American Academy of dermatology and pediatrics release of reports in support of a widespread ban on indoor tanning in those under the age of 18.
There is a widespread misconception that the ultraviolet radiation emitted from sunbeds is safer compared to the ultraviolet radiation from sunlight. This belief is not supported by scientific evidence; indeed, exposure to ultraviolet radiation from indoor tanning beds has been proven to produce damage to DNA in skin cells. This subsequently results in an increased risk of melanoma, as well as basal (BCC) and squamous cell carcinomas (SCC).
The use of sunbeds has also been associated with skin aging, ocular Melanoma, skin burns, and the suppression of the immune system. There is also a particularly heightened risk associated with the variance in the ultraviolet wavelength emitted by indoor tanning devices; raffle, consistent regulation of use is essential.
Indoor tanning devices such as sunbeds use both ultraviolet a and ultraviolet B radiation. Ultraviolet B radiation is associated with the production of cyclobutane pyrimidine dimers (CPD) and 6-4 pyrimidine pyrimidone photoproduct (6-4PP) formation in DNA resulting in direct DNA damage. Spontaneous rearrangement of these photoproducts results in distortion of the DNA backbone, which subsequently halts transcription on protein synthesis.6-4PP adducts also undergo isomerization following exposure to further UVA or UVB radiation.
UVA Radiation, in contrast, mediates DNA damage indirectly as a consequence of reactive oxygen species. Both UV A and UV B mediate indirect damage to DNA as a result of the absorption of photons by non-DNA chromophores. The products of this are reactive oxygen species (such as singlet oxygen or hydrogen peroxide) that cause mutations.
Ultraviolet radiation from the sun is predominantly composed of UVA radiation (95%). The radiation induces erythema (skin burns) at a 500-1000-fold lower dose than the UVA; however, although UVB results in delayed skin burning, UVA also causes this reaction. The ultraviolet radiation emitted from sunbeds is approximately 10 to 15 times more potent relative to solar ultraviolet radiation at its most direct exposure.
What is sunburn? | Cancer Research UK
Molecular and Cellular Effects of Tanning
There are two predominant outcomes associated with tanning:
- Immediate and maintained darkening of the skin pigment: Pigment darkening occurs immediately following exposure to both UV A and visible light; this change is resolved within 10 to 20 minutes, after which a maintained darkened pigment develops; this is typically more intense and lasts ~ two hours. Immediate and later maintained pigment tanning occur from the oxidation of melanin that has been performed, alongside the redistribution of melanosomes (organelles that produce melanin); at this stage, no new pigment is synthesized.
- A delayed tanning response: Contrastingly, delayed tanning arises between three- and five days following UVA and visible light exposure. This is associated with an upregulation of the melanocyte tyrosinase activity, The product of which, is new melanin. Both the A and B forms of UV can stimulate the delayed response; UVA-stimulated timing, however, is between two and three orders of magnitude less efficient, requiring higher doses and oxygen during exposure. Studies suggest that DNA damage occurs as a secondary effect of UV radiation which also stimulates pigmentation as a consequence of upregulating the tyrosinase mRNA and protein levels. Keratinocyte damage also activates p53 A transcription factor that binds and upregulates the production of pro-opiomelanocortin and subsequently αmelanocyte-stimulating hormone. This factor signals to melanocytes resulting in pigmentation in the cutaneous layer.
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Increased Risk of Melanoma and nonmelanoma Skin Cancer
In 2012, eight large systematic reviews which examined 12 studies comprised a total of 9,382 cases of non-Melanoma skin cancer determined a 29% increased risk for basal cell carcinoma (BCC) as a consequence of indoor tanning and a 67% increased risk for the development of squamous cell carcinoma (SCC). When the scales come up this represents over 72,000 cases of non-Melanoma skin cancer each year. An increased risk for BCC was found with younger age, whereas a high dose exposure was associated with an increased risk for BCC.
The greatest concern regarding the use of sunbeds is related to the development of malignant Melanoma. Data from the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) Registry demonstrate that the rate of new cutaneous Melanoma cases has increased year on year by an average of 1.4% over the past decade. Among the new cases, trends have demonstrated an increased rate of thinner and thicker melanomas, specifically in 15 to 39-year-old women. The pathogenesis of cutaneous Melanoma is linked to UV exposure; this, together with the high prevalence of indoor sunbed use among this population has resulted in several studies examining the association between some beds and this form of cancer.
Read Next: How is Melanoma Diagnosed and Treated?
A study conducted in 1999 in Sweden examined 571 patients with Melanoma alongside 913 controls. The odds ratio who engaged in regular exposure to ultraviolet exposure was significantly higher than those who had never used any form of tanning device among those less than 36 years of age. Moreover, there was a dose-dependent relationship found. These findings have subsequently been corroborated by several other studies.
An examination of the individual effects of UV B-exclusive high-intensity tanning technology, conducted in 2010 determined that such high-intensity, high-pressure devices subsequently increased the probability of melanoma in those using tanning technology relative to those who did not. This study could not determine any differential effect among the tanning equipment investigated. This is concordant with the findings of prior studies determining risk according to the type of indoor tanning device.
This 2010 study conducted by Lazovich et al. assessed individuals between the ages of 25 and 59, diagnosed with invasive cutaneous melanoma in Minnesota over the years 2004-2007. The research determined that the use of sunbeds and other indoor tanning devices resulted in an elevated risk of melanoma, which subsequently increased with the number of years, hours, and sessions. This risk existed across all types of tanning devices and was not associated with the age at which the individual began tanning. Quantitatively, the probability of developing melanoma as a result of tanning indoors was 1.74 (95% CI 1.42, 2.14). the adjusted odds ratio was between 2.5 and 3.0 in high-use individuals (those who had experienced 50 hours, > 100 sessions, over 10 years or more).
When accounting for the anatomic site of melanoma in each respective gender, dose-response patterns were significant for both men and women with regards to Melanoma located in the trunk. There was a differential effect between the genders with regards to head and neck melanomas, with men having a significantly higher increased risk. Conversely, women were more likely to develop melanoma of the upper or lower limbs.
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‘Benefits’ of Sun Bed Tanning
Despite the overwhelming evidence to suggest the harm and risk associated with sunbed tanning, there are some "benefits" associated with this practice. Most poignantly, is the upregulation of vitamin D as a consequence of stimulation by UVB exposure. It is important to note, however, that those using sunbeds receive between 4.5 and seven times the UV B radiation necessary possession for vitamin D production.
The synthesis of vitamin D induced by UV be is considered to be optimal at suberythemal doses. This refers to the amount of radiation that, applied to the skin, makes it turn temporarily red (erythematous). Further exposure does not result in the production of more vitamin D. Moreover, the vitamin D3 fast is produced is photo label and is therefore degraded with increased exposure to UV, and is unable to enter circulation. These findings have strengthened recommendations to suggest oral supplementations for individuals who are at risk of vitamin D deficiency, particularly as this is a safer alternative.
Moreover, several epidemiological studies have noted a correlation between UVB and reduced risks of several types of cancers including colorectal, prostate, and breast cancer, alongside non-Hodgkin lymphoma. Despite these findings, it is important to note that these correlations have not been proven and, overwhelmingly, the risk of developing cancer has been substantially proven.
Ultimately, there is a wealth of evidence to suggest that exposure to indoor UV devices such as sunbeds, is carcinogenic, and is correlated with several other high-risk lifestyles and health behaviors. Although restrictions are in place, sunbed use is prevalent, particularly among young adults, demonstrating the need for further attempts to increase public awareness, as well as the implementation of stricter restrictions.
References
- Le Clair MZ, Cockburn MG. (2016) Tanning bed use and melanoma: Establishing risk and improving prevention interventions. Prev Med Rep. doi:10.1016/j.pmedr.2015.11.016
- Madigan LM, Lim HW. (2016) Tanning beds: Impact on health, and recent regulations. Clin Dermatol. doi: 10.1016/j.clindermatol.2016.05.016.
- Gordon LG, Rodriguez-Acevedo AJ, Køster B, et al. (2020) Association of Indoor Tanning Regulations With Health and Economic Outcomes in North America and Europe. JAMA Dermatol. doi: 10.1001/jamadermatol.2020.0001
Further Reading