Maximum acceptable dose of ultraviolet radiation: A safety limit for cataract

Abstract

Purpose: To develop a method for experimental estimation of toxicity for continuous dose-response relationships. To apply this method to cataract induced by ultraviolet radiation (UVR) in young rats. Methods: After establishing experimentally the frequency distribution of light scattering of normal physiologically clear lenses, the lower limit of pathological light scattering is defined such that a certain fraction, for example 97.5%, of normal lenses scatter less light. Results: The dose-response function for UVR and cataract is determined experimentally. With this function, the dose corresponding to the lower limit of pathological light scattering may be determined as the maximum acceptable dose (MAD). The MAD0.975 for UVR 300 nm was determined to be 2.2 kJ/m2. Conclusions: The method can serve as a basis for establishing safety standards for UVR-induced cataract and probably other continuous dose-response functions.