Abstract
Scientific bodies overseeing UV radiation protection recommend safety limits for exposure to ultraviolet radiation in the workplace based on published peer-reviewed data. To support this goal, a 3D model of the human cornea was used to assess the wavelength dependence of corneal damage induced by UV-C radiation. In the first set of experiments the models were exposed with or without simulated tears; at each wavelength (215-255 nm) cells with DNA dimers and their distribution within the epithelium were measured. Simulated tears reduced the fraction of damaged cells to an extent dependent on the wavelength and tissue layer. Subsequent experiments were performed with models exposed without simulated tears; yields of DNA-damaged cells and their distribution within the corneal epithelium were evaluated at each wavelength, together with other markers of cell and tissue integrity. Unlike relatively longer wavelengths, the range of wavelengths commonly referred to as far-UV-C (215-235 nm) only induced dimers in the uppermost layers of the epithelium and did not result in lasting damage or halt proliferation of the germinative cells. These results provide evidence for the recommended exposure limits for far-UV-C wavelengths, which have been proposed as a practical technology to reduce the risk of transmission of airborne diseases in occupied locations.