Man, I hate sunburns. My paternal grandmother was deathly afraid of sun damage, skin cancer in particular, so much so that she often carried an umbrella (she called it a parasol) outside with her, even just to sit in the yard for a few minutes. Interestingly, her fears came true. She developed a few skin polyps on her nose in her last years, despite all the umbrella-toting.
My grandmother's umbrella came screaming back to my consciousness a few years ago when I burned my face off. I went downhill skiing the first (and only) time – and didn't bring sunblock. "No problem," I thought, "I'll just be here a couple hours." Oh, woe is me! How very naïve I was of the dangers of high-altitude UV radiation and snow reflection! I was there for several hours more than I thought I would be, enjoying a newfound excitement of speeding down snowy hillsides, avoiding other skiers, and tumbling onto my butt and through the air in exotic poses of flailing arms, skis, and ski poles. Great fun. I'll do it again some day.
The next morning I noticed a strange moisture seeping out of my cheeks. It was clear liquid. Was I sweating? I didn't know what to think of it, so I taped some gauze on my cheek and went to work anyhow. Once at work, I busied myself as usual. After an hour or so I noticed the gauze was soaked, so I went to the bathroom to re-evaluate my strange condition. When I took the tape off, part of my cheek went with it! And, boy, did the liquid start coming out! I was positively dripping!
Long story short, I rushed to a medical clinic (and sat for hours in their stupid waiting room) and found out I had a second-degree sunburn. The top layer of skin hadn't bothered turning red first, it just said, "Goodbye cruel sunlit world" and died. My pasty face melted off over the course of about a week. "Peeled off" would be too kind of a phrase. I didn't have enough leave time left at work, so I had to work during that time, my face covered with bandages. Not a good situation. Needless to say, I wasn't very popular with coworkers. The thought running through my mind that whole time was, "Am I going to get skin cancer from this rather severe amount of UV radiation?"
Well, researchers at
It's reported in the latest addition of _Science_: http://www.sciencemag.org/cgi/content/abstract/315/5812/625
It's been known for a long time that exposure to UV light (like in sunlight) can cause skin cancer because the energy level from the intense UV radiation causes mutations in the DNA, leading to uncontrolled cell growth (cancer) or cell death (in the case of a sunburn or, more extreme, your friggin' face melting off!). Femptosecond transient absorption spectroscopy is a very new method for visualizing extremely fast reactions at the molecular level. In short, this method uses lasers to excite molecules and an extremely fast light pulse and detector are used to look at changes in the energy levels of the molecule changed by the laser. Using this method, the researchers directly observed how UV radiation caused the formation of two chemical bonds between thymine molecules in the DNA structure. This was a pretty artificial test sample (artificial thymine-only DNA), and not in actual cells, and didn't involve all the chemical pathways involved with sunburn, but it DOES show for the first time actual DNA mutation from UV radiation, which is a huge step in understanding such mutations.
The authors probably don't go so far, but I'm wondering, could similar, non-deadly mutations happen that could lead to genetic changes in the morphology of bacteria or simple-celled organisms, perhaps even changes that could lead to development of new species adaptations, leading toward evolution?
Anyhow, this all makes me even more concerned about skin cancer and my little bout with my skiing incident!