Ultraviolet rays damage the skin hours after exposure

From now we will have to be much more careful when sunbathing or using tanning booths. According to a study by Yale University (USA), sun lovers can experience damage to their DNA, which may be related to cancer, many hours after leaving the beach or tanning booths. The blamed for this ‘delayed’ purpose is melanin in the skin.

Until now, researchers say, it is usually considered that melanin is a pigment protection, blocking UV radiation damaging DNA and contributes to the development of skin cancer. The process begins when radiation causes lesions or breaks DNA that can lead to mutations that cause cancer, and these lesions usually appear in less than a second after UV exposure. But what has been in mice and human cells is that these lesions may appear on melanin-producing cells (melanocytes) even more than three hours after exposure to UV radiation. The finding, published in “Science” shows that melanin has both carcinogenic and protective effects.

In their work, the researchers exposed mouse and human cells to radiation from UV lamp. Thus they saw that radiation caused a type of DNA damage in which two “letters” of DNA bind and bend DNA, preventing the information they contain can be read correctly. To the surprise of researchers, melanocytes not only generate this damage immediately, but continued doing hours after the end of exposure. However, melanin cells without DNA damage generated only during exposure to UV.

If you look inside the skin of adults, melanin protects against this damage, but at the same time cause injury. The researchers tested the extent of damage that occurred after exposure to the sun avoiding DNA repair in normal mouse samples and found that half of injuries in melanocytes were ‘dark lesions’, ie formed in the dark.

Experts believe that produces UV radiation and reactive oxygen or nitrogen which excites an electron in the active melanin, and this energy release in turn leads to DNA lesions. UV light activates two enzymes combine to “excite” an electron in melanin. The energy generated from this process transferred DNA in the dark, causing the same damage in the DNA sunlight during the day. Although the news of the carcinogenic effect of melanin is puzzling, researchers also point out that there is some hope: it can give time to develop new prevention tools, such as sunscreens designed to block the transfer of power after the sun exposure.