Model application—body ‘bu yt estimates Ee ime te ete ’ For acute ingestion of cesium-137 (ingestion over a period of a few days), estimated average boty burden: can be determined as a function o> Gisc<. after ingestion for the exposed populatiox, from: Be | Be= s000° 203 t/Tb : (6) For acute deposi’“an of cesium-137 on pasturage utilized by >. cows,it has bu.-. estimated that the maximum concentration (n ‘ilk will occur about 6 days following depsition. The average body burden for various ages resulting from such changing levels in milk may be approximated by: 1. Assuming total milk intake prior to maxi- mum concentration is an acute intake u-- where ing equation (6). 2. Assuming an additional! intake using the 8B, = body ourdens (nanocuries) R.=initiai body burden, =total mtake in picocuries assuming 100 percent absorption, t=time after ingestion (days), T. = iological half-time (days), =12.8 ‘xite-*) and age (years). © nversely for acute ingestion, the total in- ti .. .m be estimated for various age groups i ..... average body burdens are known at &.c« time after ingestion. rv: ingestion of cesium-137 that decreases wick time, average body burdens within the maximum daily intake as R, in equation (7). The estimated body burden from milk consumption will be the burden from equation (6), plus the burden from equation (7). Contributions to total body burden from other contaminated foods will be additive. Figure 6 presents _the body burden for males 1 year of age, for an _ acute deposition on pasturage, where the maximum concentration of cesium-187 in milk reached a level of 2,000 pCi/liter. Figure 6 indicates that maximum burden will be reached in about 25 days for this age group. population may be estimated as a function of time from: B= 1000 Qi) © meee where Ro —bt dit’ @ ®. =1nitial rate of intake (pigocuries per day), Av = biological decay constant = ,693/12.8(x!+e-*), Ai= Intake decay constant = .693/T, T, = half-time for intake after maximum concon- rf tration (days) - eri Report No. 7 (19) indicates that for an steer sone ay cee pees acute deposition on pasturage, the total cesium137 intake from milk may be 32 times the intake on the aay of the maximum concentration 4u milk (assuming the same amount of milk is <ursumed each day). The portion of the total intai. vecurring prior to maximum concentration i: about 16 percent of the total intake. The intak: occurring after maximum concentration - # about 27 times the maximum. Therefore, 27 echo mi ayCNNBAREMY eam = A Mtcame swan te ws. days may be considered the mean time of "ta cesiun.-187 in milk following maximum concentration. The half-time for intake after maxi¥aum concentration is: . T.=270.693~18 days. T2€ Cccaempmagpapene ° ago * * t._§____-} im 1 1 ey TOME AL TES REPOSITION tdteys! Figure 6. Cesium-137 body burden for males less than - 1 year of age versus time after acute deposition (assuming maximum milk concentration reaches 2,000 pCi/liter) Other assumptions regarding the pattern of milk consumption versus age may apply for various portions of the U.S. population. Body burdens for the milk consumption pattern in table 1 may be underestimated for the ages consuming quantities of milk away from home. For a continuing intake of cesium-187 (intake that occurs over a period of years), estimates of average body burdens within a population can be developed from the following: Radiological Health Data mone acs FO a