Comparison of micronucleus frequencies in poly chrome erythrocytes of mouse fetal liver induced by tritiated water

Female 10-12 week old mice of NIH strain were exposed on 10 day gestation to β-rays from tritiated water (HTO) or 60Co gamma rays at constant doses for three days. The pregnant mice were killed by cervical dislocation at 12 h after exposure to THO and 60Co. The fetal liver was removed and slides were made. Micronuclei of poly chrome erythrocytes (PCE) were scored under a binocular microscope. The experimental results showed that the total accumulative doses from β-rays of HTO in the three days were 0, 0.047, 0.093, 0.282, 0.564, 0.846 and 1.270 Gy, and the frequencies of micronuclei of PCE in the fetal liver were 1.64, 2.30, 6.81, 8.43, 12.37, 14.46 and 18.52 per mille respectively. The total accumulative doses from 60Co gamma rays in the three days were 0, 0.10, 0.25, 0.50, 0.75, 1.00, 1.25, and 1.50 Gy, and the frequencies of micronuclei of PCE in the fetal liver were 1.64, 4.7, 5.5, 6.4, 6.9, 6.7 and 8.3 per mille, respectively. The RBE of beta rays from HTO at dose range of 0.4-0.1 Gy were 5.5-3.5