This project was initiated to provide epidemiologic data relative to skin cancer and solar ultraviolet radiation. Through these studies NCI participates in a continuing basic research effort involving several Federal agencies and responds to Public Law 95-95 (amendment to the Clear Air Act of 1977), which is a commitment to the ozone protection policy. The need for these data has existed since we have learned about the decomposition of stratospheric ozone by nitrogen oxides and chlorofluoromethanes (CFMs). Federal regulatory agencies have already banned the use of aerosol spray cans which use CFMs as propellants. The National Academy of Sciences (NAS) has warned, in several publications from 1975 to 1984, that an eventual decrease in stratospheric ozone sometime in the 21st century will lead to increased amounts of solar ultraviolet radiation (UVB 290-320 nm) exposure on earth. In its most recent report to Congress, NAS recommended that (a) the effect of an increase in UVB radiation on the incidence and mortality of skin cancer and malignant melanoma should be determined and that these predictions must take into account social and demographic factors, and (b) measurement of annual UVB insolation at specific geographic sites should be continued. New estimates of skin cancer risks and relative risks are being developed for specific host and environmental factors. The host attributes include skin complexion, ethnicity, skin conditions (e.g. warts, psoriasis, moles, dry skin, etc.), ability to burn/tan; environmental factors include outdoor exposure, occupation, ionizing radiation exposure, chemical and industrial exposures (e.g., coal tar, pitch, arsenic, dust, oils, etc.). These data should enhance the progress of other programs dealing with skin cancer prevention, intervention or screening. Since nonmelanoma skin cancer (i.e., basal cell and squamous cell carcinoma) information is not being collected routinely by the NCI, final results from this project will augment NCI's task in providing epidemiologic data for all malignancies.