This project provides epidemiologic data and statistical analyses relative to the etiology of skin cancer, including malignant melanoma. In particular, we measure and clarify the association of disease incidence and mortality with nonionizing solar radiation exposure. Through these studies, NIC provides basic research in response to Public Law 95-95 (Amendment to the Clean Air Act of 1977), which is a commitment to the stratospheric ozone protection policy. The need for these data and analyses of potential human risk has existed since we learned about the decomposition of stratospheric ozone by nitrogen oxides and chlorofluoromethanes (CFMSs). Most recent reports indicate that ozone depletion will be more than 16 percent by the mid-21st century. This will lead to increased amounts of solar ultraviolet, specifically UVB (290nm to 320nm), exposure on earth accompanied by increased incidence in disease. We developed new statistical methodology designed to measure the degree of skin cancer (i.e., basal cell and squamous cell carcinoma) risk according to specific constitutional and environmental factors. Age-race-sex specific relative risk estimates were derived from select geographic areas which vary greatly in the degree or intensity of UVB exposure. We found highest relative risks for caucasians who had been treated for moles (5:1), followed by excess risks (of 2:1 to 4:1) for individuals with histories of exposure to radiation (ioninzing), coal tar or pitch, arsenic, or those with acne, psoriasis or warts, or those with outdoor jobs. Fair skin complexion, freckling, inability to tan, and Irish/Scottish ancestry were factors also found to be associated with higher risk to skin cancer (about 2:1). Of major concern has been our projection of incidence of cutaneous tumors. In the United States, we estimate an averge annual increase of six percent for melanoma, and three percent for skin cancer. Results from our mathematical models indicate that the effect of UVB is significant for each type of skin malignancy, including melanoma, even after adjusting for demographic, constitutional and other environmental factors.
