PURPOSE: To investigate the biological effect of tritium on mouse at low dose-rates. MATERIALS AND METHODS: Mice ([C57BL/6N x C3H/He]F1) were exposed to beta-rays by continuous administration of tritiated drinking water throughout their lives at low dose-rates of 3.6, 0.9, and 0.2 mG/day. RESULTS: Including the previous study, the tumour frequency was 70 to approximately 80% for exposure in the range 240 mGy/day to 9.6 mGy/day. Frequency of tumours decreased with decrease of dose-rate to 50% comparable to the controls. Restricting to thymic lymphomas, a linear relationship in a semi-log plot was found between the frequency and the dose-rate above a threshold dose-rate of 12 mGy/day. There was a 'tail' to this relationship down to 0.9 mGy/day. A similar pattern resulted for the relationship between the life-shortening and the dose-rate. The threshold dose-rate of 3H beta-rays, 2 mGy/day (with a tail down to 0.2 mGy/day), was much lower than that of gamma-rays, 20 mGy/day (tail down to 2 mGy/day) derived from other studies. CONCLUSIONS: These studies suggest that there exists the threshold dose-rate in the biological effects of radiation, and that the threshold dose-rate for 60Co gamma-irradiation is higher than that for 3H beta-irradiation.
PURPOSE: To investigate the biological effect of tritium on mouse at low dose-rates. MATERIALS AND METHODS:Mice ([C57BL/6N x C3H/He]F1) were exposed to beta-rays by continuous administration of tritiateddrinking water throughout their lives at low dose-rates of 3.6, 0.9, and 0.2 mG/day. RESULTS: Including the previous study, the tumour frequency was 70 to approximately 80% for exposure in the range 240 mGy/day to 9.6 mGy/day. Frequency of tumours decreased with decrease of dose-rate to 50% comparable to the controls. Restricting to thymic lymphomas, a linear relationship in a semi-log plot was found between the frequency and the dose-rate above a threshold dose-rate of 12 mGy/day. There was a 'tail' to this relationship down to 0.9 mGy/day. A similar pattern resulted for the relationship between the life-shortening and the dose-rate. The threshold dose-rate of 3H beta-rays, 2 mGy/day (with a tail down to 0.2 mGy/day), was much lower than that of gamma-rays, 20 mGy/day (tail down to 2 mGy/day) derived from other studies. CONCLUSIONS: These studies suggest that there exists the threshold dose-rate in the biological effects of radiation, and that the threshold dose-rate for 60Co gamma-irradiation is higher than that for 3H beta-irradiation.
Authors: Ludwig Feinendegen; Philip Hahnfeldt; Eric E Schadt; Michael Stumpf; Eberhard O Voit Journal: Radiat Environ Biophys Date: 2007-12-18 Impact factor: 1.925
Authors: Werner Olipitz; Sheena Hembrador; Matthew Davidson; Jacquelyn C Yanch; Bevin P Engelward Journal: Health Phys Date: 2010-05 Impact factor: 1.316