It is almost impossible to miss the public health warnings about sun exposure and tanning. The recent ‘darker side of tanning’ campaign has been hard to avoid. However there are other voices and some people still talk about having a healthy tan (to avoid burning). Even popular health figures like ‘Dr Oz’ give out mixed messages.
On the one hand, according to SunSmart Victoria “at least two in three Australians will be diagnosed with skin cancer by the age of 70” , on the other the tanned look is still popular. It is easy to see the motivation behind public health messages that try to reduce skin cancer but is all tanning really bad?
Perhaps it should not be surprising that new research suggests that, yes, it really is. This research is, perhaps, a little more interesting than it seems at first glance as it goes a bit further than just saying ‘tanning is bad’ (which we’ve heard before) but describes how tanning causes skin cancers. In particular it shows that there are two pathways by which ultraviolet light causes skin cancers.
Ultraviolet B, responsible for sunburn, is well known to cause skin cancer later in life. Ultraviolet A, however, while known to cause ageing in skin has been a bit more mysterious. This research shows that ultraviolet A is, indeed, damaging but only in tanned skin. So untanned skin is safe from ultraviolet A (though not ultraviolet B) but tanned skin is vulnerable to both.
Well how do they know that? The research, done in the United States and funded by the National Institutes of Health, used mice that had been genetically modified to be vulnerable to melanoma and to have skin cells more similar to human skin than normal mice. They exposed young mice to different kinds of ultraviolet light (just ultraviolet A, ultraviolet B, both or none). When the mice were older they compared the rates at which they developed melanoma. They found that while ultraviolet B was far more carcinogenic than ultraviolet A that ultraviolet A was still dangerous when the skin had been tanned.
The doses of ultraviolet used were modelled on the ratios of ultraviolet light in sunlight and are also similar to the amounts of ultraviolet A that you might get in 6-12 minutes in a tanning bed.
So is tanning safe? No. To some extent we already knew that but this researches provides a new perspective on how dangerous it can be.