In a blog post last week we highlighted the mechanisms by which a tanning bed (solarium) can cause skin cancer, following new statistics on melanoma from the UK. Yet, individuals continue to use solariums – despite their risks – and much debate is ongoing about their exact impact upon human health, particularly with regards to vitamin D.

One of the key arguments made by advocates of solariums is that exposure to ultraviolet (UV) radiation is essential for the production of vitamin D. Tanning beds are, in theory, a good source of this nutrient during the winter months or in locations which don’t receive much sunlight throughout the year. Yet, to consider this reasoning, it is first important to understand the science behind these concepts.

The synthesis of vitamin D within the body

Vitamin D is a prehormone manufactured in the skin when exposed to UV radiation. A small amount is essential for the human body to function, particularly for bone health and calcium absorption; for more information, refer to this article.

UV light, a type of electromagnetic radiation invisible to the human eye, can be separated into three different bands: UVA (wavelengths 400-320nm), UVB (320-290nm) and UVC (290-100nm). Of the UV radiation that reaches the Earth’s surface from the sun, approximately 6% is UVB and 94% UVA; UVC is blocked by the ozone layer.

Generally, most of the radiation emitted by tanning beds (over 95 percent) is in the UVA spectrum, with only a fraction in the UVB spectrum. However, it is UVB wavelengths of radiation which induce vitamin D synthesis. Therefore, most solariums are only able to marginally stimulate the synthesis of vitamin D.

Furthermore, in most cases, the incidental sun exposure people get, in addition to the vitamin D they receive from their food, is sufficient to maintain a healthy level. In circumstances where this is inadequate, most physicians and health authorities (including the World Health Organization and American Academy of Dermatology, among others) recommend changes to diet or vitamin D supplements (supervised by a doctor). These are considered safer ways to boost the intake of vitamin D than exposing the body to the damaging effects of UV.

UV radiation emitted by solariums significantly increases the risk of all types of skin cancer; squamous cell carcinoma, basal cell carcinoma and the deadliest form, melanoma. UV radiation can also induce sunburn, scarring, pre-cancerous lesions (actinic keratoses), Bowen’s disease (hard, scaly skin), eye damage (i.e. cataracts), photoaging (i.e. wrinkles), and suppression of the immune system which may increase the chance of infection or disease.

Tanning beds are able to produce UV radiation which is five times as intense as midday summer sun, greatly enhancing their potential to damage human skin; a far cry from the health benefits touted by some in the tanning industry.

As our knowledge of the skin, vitamin D production and UV radiation expands, more and more people are paying heed to the risks posed by solariums. However, a significant proportion of the population – particularly young women – continues to ignore the dangers to their health in pursuit of ‘beauty’. By publicly exploring some of the less well understood arguments, hopefully the horrific rates of skin cancer caused, in part, by solariums can be reduced.

References

Coelho, S.G & Hearing, V.J, 2009, ‘UVA tanning is involved in the increased incidence of skin cancers in fair-skinned young women’, Pigment Cell Melanoma Research, 23:57-63.

Wolpowitz, D & Gilchrest, B.A, 2006, ‘Vitamin D questions: How much do you need and how should you get it?’, Journal of the American Academy of Dermatology, 54: 301-317.

World Health Organization, 2010, Sunbeds, tanning and UV exposure, accessed 15th June 2010, <http://www.who.int/mediacentre/factsheets/fs287/en/print.html>.