How Sunlight Ages Skin and Promotes Cancer

An unwritten rule in science is that we don’t understand something until we know how it works.  We see that people who are out in the sun a lot get wrinkled skin.  Does that mean sunlight causes the wrinkles, or is there something else?

Well, now we know.

The answer to the question also answers another age old question for many:  why did I have to take chemistry in high school?

The key concept is the free radical — no, not a terrorist out of jail.  It’s an atom that’s missing a valence electron and thus becomes highly reactive with other elements.  In this case, those other elements are part of the DNA of skin cells.

Ultraviolet rays in sunlight (UVA and UVB) create free radicals of oxygen in upper and lower layers of skin.  This radicals can alter the DNA in these cells, particularly in the mitochondria — the “power plant” of the cell that drives continuation and reproduction.

These changes in mitochondria cause (1) the loss of elastin and collagen (hence wrinkling) and (2) onset and aggravation of skin cancers.  Not good.

Thanks to a research team at the University of Newcastle (UK), these processes have been demonstrated and documented.  That matters because it moves the discussion of the role of sunlight from conjecture and hypothesis to fact.  It can also lead to the creation of more effective sun screens.

The finding comes at a very opportune time.  We are experiencing a rapid growth in diagnosis of melanoma.  There has been a debate about whether this growth is due to better diagnostic tools or to a real increase in cancer incidence.

We also know that loss of ozone and other changes in the earth’s atmosphere is increasing our exposure to the UVA and UVB components of sunlight.  These changes are putting humans at risk — today, not at some remote time in the future.

These findings also end the discussion as to whether tanning beds are safe.  We now know how they harm people.  Damage is immediate.  There is no safe age.

Whether we can get governments to act, it’s essential for individuals to protect themselves and to do so immediately.  End of discussion.

A tan may be fashionable.  Wrinkles usually aren’t.  Cancer never is.

UVA and UVB rays are also major issues with rosacea (source:  Medscape).  Daily use of a broad spectrum sunscreen is recommended for all persons with rosacea.


(1) Jennifer A Latimer, James J Lloyd, Brian L Diffey, Paul J Matts, Mark A Birch-Machin. Determination of the Action Spectrum of UVR-Induced Mitochondrial DNA Damage in Human Skin Cells. Journal of Investigative Dermatology, 2015; DOI: 10.1038/jid.2015.194

(2) Newcastle University. “Action spectrum of sun skin damage documented.” ScienceDaily. ScienceDaily, 26 June 2015. <>.




(6) “The Epidemic of Nonmelanoma Skin Cancer,”


  1. Free radicals are the reason we need to consume antioxidant rich food. These annoying unpaired electrons mostly stem from our environment, i.e. radiation, smoking, pollution, herbicides, etc. Free radicals are so highly reactive that if left unchecked, the reaction will cascade creating a domino effect by disrupting neighboring atoms which will eventually lead to some type of cancer because our cells become damaged. I advise all of my friends regardless of age or race to protect themselves. Plus, no one wants to age prematurely. Right?


  2. Your comment is excellent.

    Unfortunately, given continued demand for tanning beds and public complacency over chemicals in the air and in the food supply, it would appear that a lot of people don’t care about aging or dying prematurely.


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