What happens to your DNA when you get too much sun?
Too much sun demonstrably damages your DNA and increases the risk of skin cancer. Protect your skin, especially if you have a fair skin type or a family history of skin cancer.
UV radiation directly damages your DNA. Even one hour in the sun causes large-scale damage to the genome, in the form of so-called photolesions: spots where the DNA structure becomes distorted. If your cells fail to repair that damage in time, permanent mutations can develop, or the cell dies.
It is not only DNA that takes a hit: UV also damages RNA, the 'messenger' that translates genetic information into proteins. Damaged RNA strands cause the protein-making machinery in your cell to stall. New research suggests that this stalling may actually be the main reason cells die after UV exposure, more so than the classic DNA-damage response. At the same time, UV also generates aggressive oxygen molecules that cause additional damage to DNA, fats and proteins in your cells.
Repeated exposure, through sunlight or a sunbed, accumulates that damage. This substantially raises the risk of skin cancer: not only the more deadly melanoma, but also squamous cell and basal cell carcinoma. How large that risk is for you personally depends in part on your skin type, hair colour and genetic predisposition. Furthermore, not every region of your genome is hit equally hard: the way your DNA is coiled and packaged determines which sections are more vulnerable. This explains why the same gene mutations keep appearing in skin cancer patients. UV also suppresses the immune system in your skin and changes which genes are switched on or off, though exactly how these processes contribute to cancer development is not yet fully understood.
Regarding UV nail lamps used in manicures: these emit UVA radiation and can cause DNA damage in laboratory studies. Cases of skin cancer on the hands of people who used them intensively over many years have been described. The evidence for a direct causal link is, however, limited. At normal usage levels, the doses fall within safety standards, although some lamps have been measured that exceeded those limits. Caution is therefore appropriate, but there is no need for panic.
Protective strategies are being actively investigated. One early experimental study (not yet tested in humans) showed that a combination of umbilical cord cell-derived particles and a compound from green tea, applied via microneedles, was able to reduce UV damage in skin tissue. This is interesting but still far from clinical practice.
The claims about direct UV-DNA damage and skin cancer are based on strong, causal evidence from multiple studies. The RNA-damage pathway and oxidative stress are plausibly causal but somewhat less well supported. The nail lamp risk rests on laboratory studies and case reports, not on prospective population research. The experimental treatment has only been studied in animal and lab models.