ACUTE MORTALITY OF MICE AND RATS EXPOSED TO 14 MeV NEUTRONS.
ARMED FORCES RADIOBIOLOGY RESEARCH INST BETHESDA MD
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C57BL mice, C3H mice, and Sprague-Dawley rats were exposed to 250 kVp x rays or 14 MeV neutrons and mortality data collected for 30 days thereafter. The whole-body, bilateral x irradiations over the range of 378 to 918 rads were delivered at approximately 21 radsmin. The whole-body rotational neutron irradiations utilized midline tissue doses in the range from 282 to 707 rads. C57BL mice and Sprague-Dawley rats were exposed at a neutron dose rate which varied from 15 to 35 rads per minute averages approx. 20 radsmin. C3H mice were exposed at 15-50 averages approx. 20 radsmin or 3-5 radsmin to investigate the possibility of dose rate effects. The LD 5030 values for x rays and 14 MeV neutrons, respectively, were C57BL mice -- 680 and 432 rads C3H mice -- 704 and 537 3-5 radsmin or 480 15-50 radsmin rads Sprague-Dawley rats -- 810 and 494 rads. The relative biological effectivenesses RBE for 14 MeV neutrons using 30-day mortality as the end point for comparison and 250 kVp x rays as the reference radiation were 1.6, 1.5, and 1.6 for C57BL mice, C3H mice, and Sprague-Dawley rats, respectively. A dose rate effect was evident since the LD 5030 value for C3H mice exposed at 15-50 radsmin was significantly lower 480 rads than that of mice exposed at 3-5 radsmin 537 rads. Of the strains studied only the mean survival time of C3H mice was significantly less when exposed to 14 MeV neutrons at 15-50 radsmin than when exposed to x rays. Author
- Stress Physiology