Long-term effects of laser therapy, including the possibility of an increased risk of cancer, have not been studied. Some researchers have observed changes in atypical moles (dysplastic nevi) after laser hair removal. Therefore, they suggest caution in the use of cosmetic laser therapy for people with a personal or family history of skin cancer or atypical moles, until further research determines whether these changes may be malignant or not. Laser therapy uses non-ionising radiation in the form of a concentrated light source that produces a very fine laser beam. In the case of laser hair removal, the laser beam is used to kill hair follicles (cells where hair grows from), resulting in the loss of hair growth from those follicles. Laser therapy does not use the same ultraviolet (UV) wavelengths as those found in sunlight (i.e. UVA and UVB), which are known to damage the DNA in cells and cause skin cancer. Non-ionising radiation is also different to ionising radiation (e.g. nuclear radiation, X-rays), which is also known to cause cancer. In addition to hair removal, laser therapy is used for: other cosmetic (e.g. tattoo removal) and dental procedures; to treat varicose veins; for prostate, skin and eye surgery; and to remove kidney stones. It is also widely used to treat cancer, including skin cancer.