Ultraviolet radiation and skin cancer in mice and men: accumulation of effect and uncertainty of prediction.

Studies on mice exposed to repeated doses of UVR (35 yr ago) and recent epidemiologic investigations and measurements of carcinogenic radiation on patients with nonmelanoma skin cancer showed that repeated doses accumulated. The effects of factors such as genetics, human behavior, kind of skin, variation in intensity of sunlight, etc., cannot be ecaluated quantitatively because of uncertainty. The possibility of inherent indeterminancy must be kep in mind in the study of effects of sunlight.