INFLUENCE OF DOSE-RATE AND DOSE DISTRIBUT ION ON THE INCIDENCE OF LUNG-TUMORS AFTER INHALATION OF ALPHA-EMITTERS

We have discussed experimental results reported on the influence of do se rate and dose distribution on the incidence of lung tumors after in halation exposure to alpha emitters. New experiments have been carried out to characterize the range of tumor risk which could vary over mor e than a factor 20 depending on the alpha activity of the inhaled part icles. Long term effects induced in rats after inhalation of poorly so luble (NpO2)-Np-237,, and industrial PuO2 with a similar granulometry will be compared, the specific activities of which varying within a fa ctor 500.