68 EFFECTS OF IONIZING RADIATION Table 5.1.—Biologically Hazardous Internally Deposited Fission Products Rabto-ELEMENT Sré? ye TyPE! or RADIATION FISSION! ABUNDANCE PERCENT RaDIo.. ! Dars Ongan BIo.. 23 Days B 8 4.6 5. 9 53 57 3.9 x 108 > 500 42 20 Zr B, ¥ 8, ¥ 3.7 Ru! [31 Bato gB 8, + B, 0. 5 2.8 6. 0 Rui FRACTION REACHING CRITICAL HAUP LIFE 6.4 Lai4o B, + 6. 0 Celll B, ¥ 5. 7 Pris Cel4 B 8, ¥ 5. 4 5. 3 65 365 8 12.8 17 28 13. 8 275 > 100 20 180 ~~ 200 35 > 100 50 500 By INGESTION | By INHALA. , TION . 25 2.8 x 10-4 . 35 0. 22 0. 14 . 04 . O4 0. 2 . O07 0.15 . 20 1.2 x 10-3 0. 1 . 25 1,3 x 107-3 2x 10-‘ . 063 0. 10 From: t Seaborg and Perlman, Rev. Mod. Physics, 20:585, 1948. 2 Hamilton, J. G. Rev. Mod. Physics, 20:718, 1948. 3 Handbook 52, U. 8. Dept. of Commerce, National Bureau of Standards. general, long radiological and biological halflives and produce high-energy beta particles. Thus, they cause greater damage to bone and to the radiosensitive bone marrow than to other tissues. The damage to the blood formingtissue results in a reduction of blood cells, and thus affects the entire body. Information on the biological effects of internally deposited isotopes is derived from the limited studies of accidental radioisotopic poisoning in humans, or from animal experimentation. The best documented data on the effects of small amounts of internally deposited emitters in humanbeings are obtained from studies of radium poisoning. As a result of radium deposition, terminal anemia, bone necrosis and osteogenic sarcoma appeared after a numberof years. The residual activity in the body associated with these effects is 1 to 2 micrograms of radium. Radium is a particularly hazardous element when deposited internally because of its long biological and radiological half-life. Very few data are available on the long term biological effects in humanbeingsof the shorter lived isotopes such as Sr*, I, P® and Na”. The metabolism, excretion and biological effects of a number of fission products have been Sdetise ry studied in animals by Hamilton (1), Abrams (2), Bloom (3). However, most of these studies do not cover the problem of the long termeffects in animals produced by small amounts of internally deposited isotopes. Few data are available concerning the effects of internal contamination with mixed fission products from nuclear detonations. Contamination is not produced by every detonation of a nuclear device. For example, no internal contamination was detected in individuals exposed to the air burst at Nagasaki and Hiroshima. In field tests of the contaminating type of atomic detonation, animals that inhaled fission products during short periods of exposure were found to haveinsignificant amounts of internal contamination. The long term effects (primarily malignant changes) resulting from radium deposition have been used to set the limits for maximumpermissible body concentrations of a few bone seeking radioisotopes in the body (5). Maximum permissible body content of other radioisotopes are estimated on quantities resulting in a dose of 0.3 rem per week to the tissue of highest, concentration.