A few days ago, I saw this photo on a friend's Facebook feed, accompanied by a caption claiming that it showed a truck driver who had exposed half his face to the sun for 30 years.
There wasn't any link and naturally, being Facebook, I assumed this was probably not an accurate description of what was going on in the photo and kind of just brushed it aside.
And then Mo Costandi posted the same photo on Twitter along with a link to its original source—The New England Journal of Medicine. Oh, s&*%.
The patient reported that he had driven a delivery truck for 28 years. Ultraviolet A (UVA) rays transmit through window glass, penetrating the epidermis and upper layers of dermis. Chronic UVA exposure can result in thickening of the epidermis and stratum corneum, as well as destruction of elastic fibers. This photoaging effect of UVA is contrasted with photocarcinogenesis. Although exposure to ultraviolet B (UVB) rays is linked to a higher rate of photocarcinogenesis, UVA has also been shown to induce substantial DNA mutations and direct toxicity, leading to the formation of skin cancer. The use of sun protection and topical retinoids and periodic monitoring for skin cancer were recommended for the patient.
Basically, this gentleman does not yet seem to have skin cancer. Instead, the skin on that side of his face had thickened (a sign that his skin cells aren't growing and sloughing off in a normal way). The elastic tissue on that side of the face had also started to degenerate, leaving deep wrinkles, as well as wide pores that became multiple blackheads. Also, small cysts had formed around the follicles of fine hairs on his face.
Read more about how exposure to UVA rays from the sun can cause skin damage and premature aging.
Maggie Koerth-Baker is the science editor at BoingBoing.net. She writes a monthly column for The New York Times Magazine and is the author of Before the Lights Go Out, a book about electricity, infrastructure, and the future of energy. You can find Maggie on Twitter and Facebook.