RMI Nuclear Justice Documents

94 THE SHORTER-TERM BIOLOGICAL RAZARDS OF A FALLOUT FIELD Tapstk I-—-RESIDUAL INJURY AT VARIOUS TIMES AFTER RADIATION EXPOSURE AS MEASURED BY DEPRESSION OF THE LDn30 DAYS Ltye-30 days '{t) Rostdual from first dose? (per- 520 562 516 548 597 79 37 83 53 6 200 200 200 200 446 ATT 491 524 a7 61 55 34 400 400 400 400 400 400 400 400 264 (11 days)_ 1,920 (80 days)... 3,100 (125 days)......-. 236 261 315 318 366 562 565 509 91 85 71 70 58 9 7 3 None None 4-264 hr control_...__.. 504 hr control__. Initial dase (ry 100 100 100 100 100 None None Time to seroud dose (hrs) 144 (6 days). 504 (21 days) 1,820 (80 days)... 1,920 hr control_ 3,100 hr control__.__ cont) 599 |.------601 591 519 the fast component. These points and the regression line are shownin Figure 3. The halftime for repair of this component was about 9-10 hours. Tu summary, when 30-daylethality was used. as a biological end-point, (here appeared to be two exponential components to the repair proe- ess, a slow componentrepairing with a half- time of about 30 days and a fast component repairing with a half-(ime of 9-10 hours. The size of the initial dose did not appear Lo influence the repair process. There was no evidence of a nonrepairing residual injury. Tante IZ—-RESIDUAL INJURY AT VARIOUS TIMES AFTER RADIATION EXPOSURE AS MEASURED BY DEPRESSION OF THE LD»100 HOURS Initial dose a) 400...--.-- were replotted as log percent residual vs. time. (This resulted in a curved regression line that could be adequately described by the sumof These lines were tenta- tively identified as representing a slow component and a fast componentof the repair process. The experimentally determined values at each time interval were averaged and those for 600..-.--. time intervals of 32 hours or more were plotted as a function of time. These values represent the slow component in repair. They are plotted with their calculated regression line in Figure 2. It can be seen from this figure that the half-time for repair for the slow component was about 33 days. By subtracting the contribution of the slow component from the total residual, it was possible to determine the half-time for repair of In the second series of studies, mice were exposed to 400, 600 or 800 r and at time intervals of 2, 4, 8, 24, 72, 240, or 336 hours a second dose was delivered to determine the LD,-100 hours. In this case, we were dealing primarily with injury to the gastrointestinal tract, since it is injury to this system that results in survival times of this magnitude. Residual damage was calculated as hefore. Table I[ summarizes the results of these studies. As in the case of the LDy-80 day studies, the 800... ---.-- Time to second dose dhrs) LDse100 hes! tr) 2 4 4 8 24 72 240 336 770 872 894 784 884 931 944 979 1025 1025 1038 1025 1025 1025 1021 1052 64 38 36 60 36 24 19 18 05 1 2 4 4 8 8 24 24 48 48 72 72 508 640 684 872 660 648 730 780 765 780 900 810 830 1038 1038 1038 1038 1065 1038 1065 1038 1065 1038 1065 1038 1065 88 66 69 61 68 65 56 43 50 43 28 38 39 2 4 4 24 336 304 483 534 1025 1025 1038 1038 86 79 72 63 1 LDs0-100 hours for the second dose. Controt LDye-100 hes w to be related to the size of the initial dose. The higher the dose, the higher the percent finding contrasts with the LDg-30 day results which indicated no differences in percent resid- ual with initial dose. described as the sumof two exponentials, These were again identified as a fast and a slow component to the repair process. The points obtained at 24 or more hours after the initial dose were plotted and regression lines of the + Percent of inittal dose remalningattime of delivery of second dose. type log R= a+ bt t =time between doses. These data are plotted in Figure 4. T my UETey F T were calculated. The slope constants for various sized initial doses did not differ significantly. They were averaged by weighting The i T T wep Perry T T TOT eT 100}- 4 sor 4 x 60; + 3 < & z A curved regression line resulted which could be where R=percent residual and T The data were replotted as before as log percent residual vs. time. residual to time was of the type 120, This residual injury measured at any time. best. empirical regression line relating percent Residual from first dose 3 (percent) 95 percent of residual injuryat all times appeared K==a+6 log i ; Paeeeat of Sfarthesecanddase, bt time of delivery of second. dose. two exponential lines. RATE OF REPAIR OF RADIATION DAMAGE IN MICE i. Oo wl @o = 3 40r- 4 a $ a 20-g w _ e 100r INITIALL DOSE Of a a 9200 INITIAL DOSE a 4400r INITIAL DOSE ~20 i i plese 10 1 = ° 4 else wial 100 i 4. rhoeveh TIME BETWEEN DOSES (HOURS) 1,000 i Nessa dt 10,000 Fievre 1.— Percent residual damage as measured by depression of the LDsy-30 days as a function of log time.