Study: Tanning is baaaaaaad
A new study appeared online yesterday at the Pigment Cell and Melanoma medical journal on the high risk associated with tanning (be it sun tanning or indoors tanning) [1].

This was a review (not systematic) of the available literature on the medical issues (DNA damage, vitamin D production, and cancer formation) surrounding tanning and Ultra Violet Radiation (UVR) but also such social and economic issues as tanning promotion by the relevant industry.

The paper starts off with some socio-economic statistics and numbers (all emphasis in all subsequent quotes mine. Also references have been removed -have a look at the original paper):
Despite public awareness campaigns, the tanning industry is growing, with at least 5 billion dollars a year in estimated annual revenue, a five-fold increase from the level in 1992. About 28 million US citizens, of whom about 70% are white teenagers and women, aged between 16 and 49 years, use about 50,000 tanning facilities, amounting to about 1 million users per day. [...] It is widely felt that an effective lobbying effort by the tanning industry has contributed to continued growth and public use of the indoor tanning industry. Teenagers are specifically targeted by the tanning industry through methods such as advertisements placed in high school newspapers including those that offer coupons for discounts and “unlimited tanning” programs. Statements about positive effects of ultraviolet (UV) lights as well as the safety and benefits of tanning in a salon are well-advertised on the Indoor Tanning Association website.
Ah, another disingenuous campaign to drive people to dubious or downright damaging modalities. But hey, you gotta look good for the summer, no?

And now for a primer on the nastiness that is UVR:
Whereas targets of UV include nucleic acids, proteins, lipids, and other macromolecules, the biological consequences for DNA structure are particularly striking, resulting in “signature” mutations which are commonly found in cutaneous malignancies in man.
[...]
While UVA has historically been implicated in skin aging, it has now been linked, along with UVB, in the development of skin cancers in animals and in immunosuppression in humans.
[...]
UVR also suppresses the normal pathways of immune surveillance responsible for eliminating mutant cells
In other words: UVR is a bad motherf***er for our skin… But how exactly is this related to tanning and how does it work? Well, in a nutshell this is what happens:
UV-mediated skin tanning. When the skin is exposed to ultraviolet (UV) radiation, some of the radiation reflects off the skin, while some penetrates deeper and causes DNA damage in keratinocytes. In response to the DNA damage, p53 is activated and binds to the pro-opiomelanocortin (POMC) promoter, acting as a transcription factor. The POMC gene product is post-translationally cleaved into adrenocorticotropic hormone (ACTH), -endorphin, and -melanocyte-stimulating hormone (-MSH). -MSH signals to melanocytes through the melanocortin 1 receptor (MC1R). The resulting elevation in cAMP increases transcription of microphthalmia-associated transcription factor (MITF), which leads to the synthesis of melanin from tyrosine. Melanin is packaged in melanosomes and transported back to keratinocytes, where the melanin localizes above the nuclei to protect from further UV exposure.
Or in understandable language: when the higher layer of cells in our skin, called keratinocytes, realize their DNA is being screwed by UVR they call for extra protection against UVR. This extra protection comes from the melanocytes (pigment producing cells) which produce more pigment (melanin) and send it back to the keratinocytes to use as a shield. This extra pigment production and movement causes the skin tanning.

Now, on to some really frightening statistics:
There are few lingering doubts from epidemiological data as well as scientific information regarding the massive risk UVR imposes on development of skin cancer. Skin cancer is the most common malignancy in the US with well over 1 million cases of non melanoma skin cancers as well as over 60,000 cases of malignant melanoma estimated for 2007 (melanoma in situ will account for an additional 46,000 cases), with skin cancer accounting for more than 50% of all malignancies. The World Health Organization has estimated that in the year 2000, up to 71,000 deaths worldwide were attributable to excessive UV exposure. The incidence of skin cancer continues to rise faster than that of any other cancer, with the lifetime risk for an American to develop melanoma estimated to have increased approximately 2000% in the past 75 years.
[...]
[One] study revealed a 75% increased risk of melanoma for individuals who had first use of a tanning bed prior to age 35 as well as a significant increased risk of melanoma in the “ever” vs. “never” indoor tanning group
In simple words: shit! Is there anything good coming out of our exposure to UVR?!? Well, apparently there is: Vitamin D production. And get the irony here: vitamin D may play a role in prevention of some forms of cancer! You get yourself under the sun to produce more vitamin D in order to prevent cancer caused by… the sun! However, to reach healthy and cancer preventing vitamin D levels, you do not need to expose yourself to UVR, as the authors state:
While vit D may indeed have anti-cancer beneficial effects, there is no benefit to utilizing UVR as the vehicle to boost vit D levels. Oral vit D supplements are routinely (and increasingly) prescribed by internists to patients with laboratory-proven vit D deficiency. The use of unreliable dose-relationships between UV and vit D production (either from sunlight or indoor tanning) to boost skin-produced vit D in the blood is medically dangerous due to the known carcinogenic risk in skin, with several of those skin cancers producing measurable risk of cancer lethality.
Bottom line: there is no safe level of exposure to Ultra Violet Radiation. Tanning actually represents damaged skin cells and dramatically increases the risk factor for cancer formation. Avoid sun exposure -hell what are we going to do in the summer? Actually, scrap that: why didn’t they tell us before summer?

But there is always something good to take out of such a gloomy paper (for me at least): I now like London even more!

---
References:
  1. Tran T-NT, Schulman J, Fisher DE. "UV and pigmentation: molecular mechanisms and social controversies". Pigment Cell Melanoma 2008, 21:509–516 []

3 Responses to this post
So, what about next summer?
:)
Next summer we’ll stay under our umbrellas, with a sun lotion of 50SPF and our coats on :-)

Better safe than sorry…
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