EFFECT OF VIDEO DISPLAY TERMINAL IRRADIATION ON URETHANE-INDUCED LUNGCARCINOGENESIS IN MICE

Female Swiss-derived SHR mice were exposed intraperitoneally to 4 inje ctions of 1% urethane at the Ist, 8th, 54th and 61st days of the exper iment (a single dose was 20 mg per mouse). Groups of mice starting fro m the Ist day were also exposed 5 days per week to 1 hour irradiation of video display terminal (VDT) or VDT+ screen filter (SF). The distan ce from VDT screen and bottom of animal cage was 38 cm. The experiment was finalized in 1 year. Longterm exposure of urethane-treated mice t o both VDT or VDT+SF was followed by slight decrease in survival time of lung tumor-bearing animals. The tendency to increase of the inciden ce of lung tumors and the number of lung tumor per mouse was observed in mice exposed to urethane + VDT as compared to those exposed to uret hane alone. The incidence of lung tumors and lung tumor multiplicity w ere significantly decreased in mice treated with urethan and VDT+SF in comparison to mice exposed to urethane + VDT. Thus, a slight promotin g effect of VDT-induced irradiation on lung tumorigenesis was observed induced by urethane in mice, and SF alleviated this effect. The dose of urethane in these experiments was rather high to show more clearly the effect of VDT irradiation on lung carcinogenesis.