Q: Given a passage and a query based on the passage, generate an unambiguous, concise and simple answer to the query from information in the passage. Note that the answer may not be present in exact form.
Studies of cells in lab dishes and test tubes have shown that sunlight and simulated sunlight (for example, from xenon or xenon-mercury arc lamps) can cause DNA damage (mutations). Studies in animals Exposure of mice, rats, and some other lab animals to sunlight and artificial sources of UV rays has been shown to lead to skin cancers. Basal and squamous cell skin cancer: Many observational studies have found that basal and squamous cell skin cancers are linked to certain behaviors that put people in the sun, as well as a number of markers of sun exposure, such as: 1 Spending time in the sun for recreation (including going to the beach) Melanoma: Observational studies have also found links between certain behaviors and markers of sun exposure and melanoma of the skin, including: 1 Activities that lead to "intermittent sun exposure," like sunbathing, water sports, and taking vacations in sunny places. 2 Previous sunburns. Additional Reading. 1 Black HS, deGruijl FR, Forbes PD et al. Photocarcinogenesis: an overview. 2 Freeman SE, Hacham H, Gange RW et al. Wavelength dependence of pyrimidine dimer formation in DNA of human skin irradiated in situ with ultraviolet light. 3 Lindahl T, Wood RD. Quality control by DNA repair. No type of UV radiation has been shown to be safe cancers have developed after exposure to UVA (alone), UVB (alone), and UVC (alone). What expert agencies say. Several national and international agencies study different substances in the environment to determine if they can cause cancer. However, this is not always the case. The signature mutation caused by ultraviolet light is a CC to TT mutation, caused when a CC dimer is mispaired with two adenine bases during replication. Because of these mutations, the connection between ultraviolet damage to DNA and cancer is quite clear. Whenever we walk in the sun, ultraviolet light (UV) attacks our DNA, making chemical changes that corrupt our genetic information. Fortunately, the most dangerous UV light never reaches us at all: the ozone in the upper atmosphere absorbs (at least for now) the energetic UVC wavelengths. The longer UV wavelengths, however, do pass through the atmosphere and fall on us. Yes. In fact, most skin cancers are a direct result of exposure to the UV rays in sunlight. Both basal cell and squamous cell cancers (the most common types of skin cancer) tend to be found on sun-exposed parts of the body, and their occurrence is typically related to lifetime sun exposure. Studies of cells in lab dishes and test tubes have shown that sunlight and simulated sunlight (for example, from xenon or xenon-mercury arc lamps) can cause DNA damage (mutations). Studies in animals. Exposure of mice, rats, and some other lab animals to sunlight and artificial sources of UV rays has been shown to lead to skin cancers. Ultraviolet light is absorbed by a double bond in pyrimidine bases (such as thymine and cytosine in DNA), opening the bond and allowing it to react with neighboring molecules. If it is next to a second pyrimidine base, the UV-modified base forms direct covalent bonds with it. Query: how does uv light cause mutations?
A:
The signature mutation caused by ultraviolet light is a CC to TT mutation, caused when a CC dimer is mispaired with two adenine bases during replication.