The micronuclear cell rate of nucleated erythrocyte of bone marrow in 30 cases of radiologists and 20 cases of normal controls have been compared. The result showed that the mioronuclear cell rate in bone marrow of radiologists is higher than that of normal contrls and the difference is significant(P<0.01)

The result also showed that there is a great sex difference

that is the rate in male is higher than that in female(P<0.01). There was no significant difference between those radiologists who had worked over 25 years and those less than 9 years(P>0.06).