Most often, skin cancer is the result of over-exposure to the sun. In some cases, UV rays directly cause skin cancer. Many studies of skin cancer, especially of malignant melanoma, show individual intolerance to sun exposure. Fair skin is more vulnerable because it contains very little pigment to decrease penetration by ultraviolet rays. A child's skin is thinner, more sensitive and therefore less protected against the penetration of ultraviolet rays.
Infants are particularly vulnerable.
And there is evidence that even a single sunburn in childhood may increase the risk of developing skin cancer later in life. All sunburns should be avoided, but particularly by children. Most people can prevent skin cancer by simply not over-exposing themselves to the sun and to ultraviolet lamps, such as sunlamps. A suntan and a sunburn are two quite distinct reactions, but both are evidence of skin injury. When you have a tan, ultraviolet rays have darkened the pigment in your skin called melanin.