"SUNLIGHT"-INDUCED MAMMALIAN CELL KILLING: A COMPARATIVE STUDY OF ULTRAVIOLET AND NEAR-ULTRAVIOLET INACTIVATION

Abstract— We have examined the relationship between the survival curves obtained with UV light (254 nm) and those obtained with a near-UV sburce (Westinghouse Sun Lamps, FS20) simulating sunlight for cultured Chinese hamster cells, C3H mouse cells, and HeLa cells. In no case do the "sunlight" survival curves have the same shape as the UV survival curves. Also, the combined lethal effects of UV and near-UV, sunlight-like exposures are not entirely additive. Hence, we conclude that (1) the cell-killing photolesions induced by these radiations are at most only partly the same, and (2) in view of (I), caution should be exercised in predicting near UV-induced dose-dependencies of other end points based upon observations with UV.