Study: Sunscreen Poses Skin Cancer Risk

If it's not one thing, it's another. While everybody knows that too much time in the sun massively increases the chances of developing skin cancer, new research suggests that a compound found in most sunscreens may also increase the chances of acquiring melanomas. Terrific. We're screwed either way.

The research, carried out at Missouri University of Science and Technology, looked into what happens to the compounds in sunscreen when they're exposed to light. In particular, they found that zinc oxide -- a staple ingredient in sunscreen -- undergoes a chemical reaction when it's illuminated by bright light that may release unstable molecules known as free radicals.

Those free radicals readily bond with other molecules, but in the process they can damage cells or the DNA contained within those cells, in turn increasing the risk of skin cancer. The tests, which were carried out in the lab using lung cells covered in zinc oxide solution, suggest that it is UV light which causes the reaction to take place most strongly. Which is, you know, precisely the kind you use sunscreen to protect yourself from.

The research, which is to be published in the Journal of Toxicology and Applied Pharmacology, suggests that the harmful effects of the free radicals increases the longer zinc oxide is exposed to sunlight. After three hours of UV exposure, half of the lung cells covered in zinc oxide solution died. After 12 hours, that increased to 90 per cent.

The big question here, of course, if whether people should be concerned. In truth, this is a small study, conducted using lung cells rather than skin cells. While there could well be plenty of truth in the notion that zinc oxide degrades in such a way that increases skin cancer risk, there's not enough data here to decide if, on balance, sun screen causes more harm than good. In fact, Dr Yinfa Ma, one of the researchers, agrees:

"More extensive study is still needed. This is just the first step. I still would advise people to wear sunscreen; sunscreen is better than no protection at all."

It will, however, be interesting to see how this strand of research pans out. If further studies -- including clinical trials -- confirm this effect to be real, the cosmetic industry will have to change the way it produces sunscreen, and quick. [PhysOrg]

Image: ldhren/Flickr

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    Aren't skin rates dropping because of 'slip, slop, slap' - which seems counter to this article's premise. At any rate shouldn't we be more afraid of nano-particles in sun cream?

    I think they are going up, but it's all attributed to ozone layer holes and the harshness of Australian sun. Either that or they are staying steady because they cancel each other out. Less skin cancer from sun but replaced by the chemical causation of sunscreen. Fun, fun.

    I already knew this before hand, but good article.

    Without having statistical data on hand to back me up, I'd suggest that the rate of decline in skin cancer due to the use of sunscreen would far outweigh the increase in skin cancer as a result of using sunscreen.

    Furthermore, and someone please correct me if I'm wrong here, but aren't the outer layers of our skin already made up of dead cells anyway? In which case, the cells in direct contact with the zinc oxide won't become cancerous, which either negates or minimises the findings of this study.

      That is correct, though it is only a very small layer of dead cells, whilst there is a possibility the sunscreen is absorbed releasing free radicals.

      In 2009 the TGA released a statement regarding the use of zinc oxide in sunscreen and damage;

      "The TGA review concluded that:

      The potential for titanium dioxide and zinc oxide nanoparticles in sunscreens to cause adverse effects depends primarily upon the ability of the nanoparticles to reach viable skin cells; and
      To date, the current weight of evidence suggests that titanium dioxide and zinc oxide nanoparticles do not reach viable skin cells; rather, they remain on the surface of the skin and in the outer layer of the skin that is composed of non-viable cells."

      Experiments like this have already been done, but this experiment only relates zinc oxide damage to lung cells rather than skin cells as noted. I'd assume if this was a big problem, trends and figures would have been picked up by the cancer council much earlier.

    Nathan, I read an article a few weeks ago that mentioned the holes in the Ozone over Aus are gone.. they've apparently relocated to the Northern Hemisphere

    Titanium Oxide has the same affect - but these oxides are only found in those "dry sun screens" the "milk" based ones dont have them from what I remember.

    We now have plumetting rates of vitamin D...pick your poison.

    They did this as a joke advertisement in Robocop.

    im wondering why they are testing the zinc oxide component of sunscreen on lung cells. whats the point of this research. if you want to link zinc oxide to skin cancer or if it increases the risk of skin cancer then the need to test it on skin. just sayin'

      This +1

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