THE FOREIGN SERVICE OF THE UNITED STATES OF AMERICA 6 April 1°5U fr. Rokuzs Kobayashi Nationa} Institute of Health Melfare Ministry TOKYO Dear Dr. Kobayashi: . On March 26 we received two samples of urine from patients at the Tokyo Univeristy Hospital. I am happy to be able to report at this time that the radioactivity of these samples is so low that the deposits of fission products in the tissues of the two patients can be accepted as well within the limits of safety, The results follow: ~ -~ 720 disintegrations per minute per liter nf ® nw n 4 Data on the individual radio-isotcpes will be telegraphed to ne in another few days. It will then be possible for me to be more quantitative in estimating the dose from absorbed fission products. However, it ds most certain thet the storage 2f Long-lived radiceisotopes is in~ Significant in these men. AS you know, the rate of excretion of fiseicn products at any given time after absorption beers a relatisnship to the quantities de- posited in the varisus tissues, The principal radiochemical constituents at this time ore due to Sr 99, LallLO end the Rare Earths, These are isotopes which have relatively snort half-lives and are eliminated from the body with comparctive rapidity either by redicactive decay or ex- cretion. In the case of these patients, Sr90 is most certainly an insignificant fraction of the total absorbed redicactivity. The permissible urinary excretion, considering the isotspes involved, would be greater, by a large fector, than the values r.ported above. T note that the newspapers continue to carry occasional state-= ments 3f the Japanese investigators ts the effect that the prognosis ‘fcr the fishermen is adversely affected by tne fact that long-life done= seeking isotopes are deposited in their tissues. It is regrettable that the public continues to be misinfcrned in this respect. Certainly the results reported above argue convincingly that only minimal, nedicclly insignificant amounts of fissiin orcducts have Seen sbsctrbed into the tissues of the two patisnts fcr ~hom resuits ime available, ~?