UV radiation -

The oncogenic effect of UV rays merits special mention because it highlights the impoance of DNA repair in car cinogenesis. Natural UV radiation derived from the sun can cause skin cancers (melanomas, squamous cell carcino mas, and basal cell carcinomas). At greatest risk are fair skinned people who live in locales such as Australia and New Zealand that receive a great deal of sunlight. Non melanoma skin cancers are associated with total cumula tive exposure to UV radiation, whereas melanomas are associated with intense intermittent exposure--as occurs with sunbathing. UV light has several biologic effects on cells. Of paicular relevance to carcinogenesis is the ability to damage DNA by forming pyrimidine dimersThis type of DNA damage is repaired by the nucleotide excision repair pathway. Reference: Robbins Basic Pathology. Pg no:200,201