Ultraviolet action spectrum for cell killing in a human lens epithelial cell line

There are many sources of ultraviolet (UV) radiation in the workplace. Action spectrum data are necessary for establishing methods to evaluate UV hazards. We determined a UV action spectrum for cell killing in the human lens epithelial cell line SRA 01/04 by measuring the viability of cells exposed to UV at 8 different wavelengths ranging from 259.5 to 300.5 nm in a carefully designed and controlled experiment. The action spectrum based on LD50 is nearly flat or falls slightly with wavelength in the short-wavelength region and then rises increasingly steeply at longer wavelengths. UV at 267.5 nm is most effective in cell killing, with an LD50 of 8.86 Jm(-2). The action spectrum for killing lens epithelial cells in humans (in vivo action spectrum) derived from the present results falls monotonically with wavelength in the range studied, suggesting that UV at wavelengths longer than 300.5 nm may also be highly effective in killing lens epithelial cells in humans and, therefore, in causing cataract. Further studies should be conducted with UV at longer wavelengths.