216 THE SHORTER-TERM BIOLOGICAL PERSISTENCE OF RADIOACTIVE CONTAMINATION IN ANIMALS HAZARDS OF A FALLOUT FIELD The carcass contained 470 to 545 sunshine units while 2 bones of the rooster analyzed contained 105 end 272 sunshine units. For comparison, an autograph of a tibia of a kitten that was exposed to the initial fallout and collected & days after the detonation is shown iu Figure 3. This animal died from natural causes at 1 year following exposure. The pattern of deposition of thefission products was similar to that observed in the rooster with dense concentration in the shaft of the bone. Thelight regions at the ends of the bone re- flect. the region of growth after the animal had been removed from the contaminated area. There was less translocation of deposited ac- Tapiy & Wet wt. Rats: oe ee ee Carcass 2. _ WKIGC Lf LL lll. WIT Lo ee do___. Rooster: (IO ne eee Femur. | IO. eee ee Tibia W5£3 272.45 the limiting process is probably carcinogenic. The Jong term effects ean be described in terms of relatively few radionnclides. By the end of the 2nd yearafter detonation, the hazard may be characterized in terms of the levels of Sr®. This is the erifical element responsible for practically all the long term effects and in terms of which the habitwbility of a contaminated area may he assesscd. The relationship between environmental availability of the contaminant and the biological retention has not as yet been clearly delineated. Further Iaboratory and field studies are required to provide data on this relationship to allow for an estimation of internal radiation hazard to human beings from the physical availability data alone. fission products are deposited internally. Evaluation of the biological effects produced by internally deposited fallout can be expressed in terms of limiting pathological processes. Fraura 1—Autoradiograph of tibia of Rongelap rooster. 0.095 ze/kg body weight which was approximately the level of activity in the rooster, The distribution of residual activity in the rat skeleton is ilustrated in the autoradiograph of the femurs of the 4 The activity is diffusely spread throughoutthe bone which suggests that these animals were born after the detonation. This diffuse activity represents the incorporation of low levels of activity over a long period of time. DISCUSSION The one exception is rat No. 4, which shows a heavy line in the epiphyseal region suggesting that the animal was a young adult at the time of exposure. tissue of these rats are presented in Table 5. 519 9. 50 54h 219 153 4.90 420427 At very low levels as observed in this study, the biclogical effects produced when these As these rats lived for a period of years on Rongelap they serve as an indicator of the internal radiation hazard in human beings inhabiting this area, The Sr®/Ca ratios for the 1210 £30 5702 1 i1% QL 583 ots 2 353 Atrelatively high dose levels (hese are damage to bone marrow, hone and to the G.L. tract. the internal radiation hazard availability of the various fission products and rats, Figure 2. 226.0 41.0 i 642 | 23 315 4 62 | 367 4 21 | : gm Ca. ? Does not inelude head, femurs, tibiae and viscera. 3 Drv weight of 2 femur halves. from fallout depends on two parameters-— 0.12 uc/ke body weight. 447 62.5 323 ditSrit/sample Ca/sample fern Srvo 18.es 2.2 dimSrv tivity than seen in the rooster. Detectible amounts of activity, however, are seen in the ends of the bone, In general, 217 STRONTIUM © LEVELS IN ANIMALS LIVING ON RONGELAP ISLAND Hi. ¥. Weiss and S. H. Cohn Dr. Coapwier (PHS). 1 didn’t happen to see on Dr. Weiss’ figures anything about the breadfruit, and 1 was wondering, did you have tu) i 4 Freure 2.—Autoradiograph of femurs of Rongelap rats. Frovre 3.--Autoradiograph of tibia of kitten collected on Rongelap, March 9, 1954. The kitten died of natural causes ai 1 year post detonation. 4 anyfigures on breadfruit or not? T know in reading the caleitum levels for breadfruit, it seemed that they ran higher than those for