Distribution in the body and excretion pattern of uranium have been investigated, following the inhalation of uranyl nitrate aerosols (concentration of uranium were 4.2μg/l and 26.4μg/l respectively) by adult rats. Amounts of uranium in the lung and the kidney immediately after the inhalation of the aerosol were about ten to several tens times greater than those in other organs, but decreased to the level of back ground after about one month. Following the single inhalation of the aerosol, the levels of uranium in liver, spleen, blood and bones were almost in back ground level during the period of one month thereafter.
However, as the amout of uranium in the liver almost coincided with that of the spleen, it is estimated that the dose delivered to the spleen is more than ten times than that of the liver, in comparison of the both weights. The excretion of uranium in urine increases, according to the inhalation of uranyl nitrate. Therefore, uranium in urine is considered as a good index of the body burden of uranium for the estimation in case of the inhalation of the uranyl compound.
