Bring Me Sunshine…

Bring me sunshineAnother day, another Press Release…..

“No safe way to suntan, new NICE guidance warns”

Just what is their problem?  After all, the sun is our friend….right?  Keeps us warm…makes plants grow…helps us make Vitamin D, thus avoiding rickets…gives us a reason to skip work and head off to the park or the beach with a crate of beers…  And everyone loves a suntan.  Makes you look healthy.  So why have NICE got such a downer on suntans & sun exposure.

One word:  Melanoma.

According to Cancer Research UK, Melanoma (ie. skin cancer) rates have been increasing steadily since the mid-1970’s.  Now part of this may be due to improved detection rates, but mostly it is put down to the massive increase in foreign beach holidays over the last 40 years.

Since the 1970’s, more of us have gotten used to going somewhere hot on holidays and spending 1-2 weeks lying on the beach, or by the pool, sizzling away.  And that can be dangerous, because sunlight contains a lot of Ultra Violet (UV) radiation, and it’s been long known that UV can damage DNA and lead to potentially dangerous mutations is human skin cells.

In point of fact, that is why you get a suntan in the first place.  I’ve spoken before (back in Trumpity-Trump) about the way that cells respond to damage, by putting the brakes on cell growth and activating repair mechanisms.  Well, there are other protective mechanisms inside cells, which are there to try and stop damage occurring in the first place.  If a cell is subjected to stress, or detects that there is something in the environment that is potentially damaging, it can respond by making proteins that will act to protect it.

We scientists lump them all together under the umbrella term Heat Shock Proteins (HSPs), because they were first discovered by heating up cells to see how they react.  But they aren’t just activated by heat, but by other damaging mechanisms.  And for skin cells, one thing that has the potential to create dangerous amounts of DNA damage is UV radiation.

Now, as I said, UV is a major component of sunlight.  And the stronger the sunlight, the higher the levels of UV.  So, if you expose your skin to strong sunlight, as you do when you are sunbathing, your skin cells will detect the increase in UV radiation, and try to protect themselves from UV-induced damage.  And one of the main ways they do this is by producing a range of HSPs known as Melanins.

Melanins are dark coloured pigments, and in skin cells there are two main types, the Eumelanins, which range from brown to black coloured and the Pheomelanins which range from pink to dark red.  Melanins are responsible for skin pigmentation – and also for hair colouring:  brown and black hair are due to the production of Eumelanins, while red hair is caused by Pheomelanins.

But, more importantly, Melanins can act to absorb UV light.  So, if skin cells detect increased UV radiation, they start to make Melanins, which absorb the UV and stop it from damaging the cells’ DNA.  Now, the upshot of this is that, because the skin cells are making more of the dark coloured pigment, the cells themselves will start to go darker.  If this keeps happening….Bingo!  The skin tans**.  And that is what you see.  That is what a suntan is.  It is the cells in your skin trying to protect themselves from the damaging effects of UV light.  And if this protection fails completely, the skin cells get damaged & burned: sunburn.  And the more damage, the bigger the risk that this damage will result in DNA alterations which could become cancerous.

The protective effects of Melanin production are well known.  And, obviously, the more Melanin that is made the better the protection.  And if the Melanin production is constant, that is better still.  This is why, according to Cancer Research UK, people from the Black & Asian communities have lower rates of skin cancer than White people.

But what this new press release tells us, is that the dangers from over-exposure to UV light MASSIVELY outweigh any protective effects of suntan-induced Melanin production.

So, remember!  Next time you are lying on the beach, admiring your tan, think what is really going on.  Your skin is only tanning because you are trying to hurt it.  Just watch out that it doesn’t try to hurt you back with Melanoma……..

** As an aside, the fact that there are different types of Melanin may also explain another peculiar effect that many people have noticed.  People who use a sunbed tend to go orange, rather than brown.  One explanation for this is that, just as Melanin is not one thing, but a range of different things (grouped as Eumelanins and Pheomelanins), UV radiation is not one thing either, but is a range of different wavelengths of light.  So, the theory is that different wavelengths of UV light are absorbed by different specific types of Melanin.  The sun produces the whole range of UV, therefore your skin makes the whole range of Melanins in response.  But, as the UV produced by a sunbed is artificial, it doesn’t have the whole range of wavelengths, so the skin makes less of the browny-black Eumelanins and more of the pinky-red Pheomelanins.  The upshot being that the artificially produced suntan from a sunbed looks less brown and more orange.

 

NICE (2016). Sunlight exposure: risks and benefits National Institute for Health & Care Excellence

Cancer Research UK (2016). Skin cancer incidence statistics CRUK website

Newton-Bishop, J., Chang, Y., Elliott, F., Chan, M., Leake, S., Karpavicius, B., Haynes, S., Fitzgibbon, E., Kukalizch, K., Randerson-Moor, J., Elder, D., Bishop, D., & Barrett, J. (2011). Relationship between sun exposure and melanoma risk for tumours in different body sites in a large case-control study in a temperate climate European Journal of Cancer, 47 (5), 732-741 DOI: 10.1016/j.ejca.2010.10.008

ResearchBlogging.org

AG McCluskey (2016). Bring Me Sunshine… Zongo’s Cancer Diaries

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