You know by now that UV rays can cause skin cancer, but here's one more reason to practice safe sun: Researchers at Stanford University have discovered that UV exposure makes human tissues more likely to tear, which can lead to potentially serious infections. Their findings were published in the Proceedings of the National Academy of Sciences.

 

According to a release from the university, Reinhold Dauskardt and colleagues subjected samples of human tissue to varying doses of UVB radiation, which is the range of ultraviolet wavelengths that are largely absorbed by the epidermis and don't penetrate to deeper layers. Then the investigators tested the samples by putting them under different kinds of stress until they tore.   The release explains that the body's outermost defensive layer, the stratum corneum, has a "brick-and-mortar" structure. The "bricks" in this model are dead cells called corneocytes, which are filled with a matrix of keratin filaments. These were not affected by UVB exposure. However, the "mortar" of skin defense, which is a layer of fatty, waxy substances that hold the skin cells together and keep water from getting through, were damaged.     "UV exposure doesn't just make the stratum corneum weaker. It also increases the actual stresses that cause the stratum corneum to fail. So it's sort of a double-whammy, which we didn't expect," Dauskardt said. In other words, UV radiation introduces more force that drives skin cells apart while making the cells more helpless to resist.   As a reminder, even on cloudy days and even during winter weather, the sun's rays can penetrate and wreak havoc with your skin. Don't abandon sunscreen just because summer is over!