COMPARISON OF MELANOCYTES AND KERATINOCYTES IN ULTRAVIOLET-INDUCED DNA-DAMAGE PER MINIMUM ERYTHEMA DOSE SUNLIGHT - APPLICABILITY OF ULTRAVIOLET ACTION SPECTRA FOR RISK ESTIMATES

Action spectra are being used in risk estimates for ultraviolet (UV) d amage. The purpose of our investigation was to compare the susceptibil ity of cultured melanocytes and keratinocytes to UV-induced DNA damage per minimum erythema dose (MED) and to determine whether the predicti ons made with action spectra agree with the damage actually induced. G enetic damage was measured as the number of T4-endonuclease V-sensitiv e sites (ESS). Predictions made with the action spectrum for the induc tion of DNA damage in melanocytes after irradiation with sunlight and a solar simulator were 15.9 and 13,2 ESS per lO(8) daltons per MED, re spectively; with the action spectrum for the induction of DNA damage i n keratinocytes the predictions were 12,1 and 9.8 ESS per 10(8) dalton s per MED, respectively. To determine the actual damage per MED, cultu red cells were irradiated with sunlight or a solar simulator, and MED was determined with an erythema UV meter. The induction of DNA damage in melanocytes after sunlight and solar simulator irradiation was 8.01 and 6.7 ESS per 10(8) daltons per MED, respectively, and in keratinoc ytes 7.49 and 7.12 ESS per 10(8) daltons per MED, respectively. This w as considered to be in agreement with the predicted data. The use of a ction spectra for risk estimates in melanocytes appears justified.