50 5 The value OR,_, =0.25 is an approximate value [t is obvious that use of this technique to esti- obtained expertmientallyon rats fed a stock laboratory diet.** The discrimination factor of 4 for mate the Sr°® body burdens of the Marshallese people is also complicated by the uncertainty of their diet. The esumates of average dietary intake of the Marshallese since their return to Rongelap calclum against strontium from diet to bone in man has been reported by Schulert*’ and Brvant.*! A more appropriate value tor the rats in this situa- are approximate, because the diet has varied dur- tion might be the ORyyae-a:e1=0.16 obtained bya study of wild kangaroo rats living in the Nevada ing the past several vears. A study made in 1958 yielded daily Sr°’//Ca intake levels of 67.5 Sr units (Sr°°/Ca), = (Sr? /Caj),(OR,_,)(OR,_,) Sr°° Ca levels in the various foods are shown in (upC Sr°"'¢ Ca), provided that coconut crabs(see desert.*” The Sr*® body burdenis then Figure +) were excluded from their diet.** ** The Table 31. This study was based on the analysis of various food samples in what may be considered =(8.4x 10")(0.7)(0.16) =924 uC Sr°*/g Ca. The value obtained in this manneris approxiobtained by direct radiochemical analysis of the was assumed that half the calcium in the diet was derived from food not native to Rongelap Island. between the indirect environmental estimate of intake of 67.5 Sr units, the equilibrium Sr°° body burden for the Rongelap people is calculated as tissues of rats living on the island during the 2year period following detonation.** This difference From the discrimination factor of 4 and the daily the body burden of Sr?°/Ca and the results of direct analysis may reflect either errors in the discrimination ratios or perhapslack of equilibrium between the Sr®°/Ca in the animals and in the =17 mpC. This is very close to the equilibrium body burden (23 muC) estimated by Woodward from the urinalysis data.°° although the 13 adult rats analyzed by Held*’ at + years had values close to the 2-year level, 443 181 wu Sr°°/g Ca, the life span of the rat is only 2 years. gather samples of meals to be assayed for Sr®/Ca content. However, since the Marshallese were found to subsist to a large extent on foods notindigenous to the area, such as C rations, rice, and soil at 2 years. The latter possibility exists, since, *( r 2 =’, J ok emma ee an average diet. The data were obtained froma study of the diets of 14 males on Rongelap.*’ It mately twice the value 470 to 545 uC Sr°?/g Ca Spee ees a I Mie Another effort was made inthe 1959 survey to.” ’ Table 31 Estimate of Sr?? in Diet of Rongelap Adults, 1958 A Daily intake,* e@ (wet wt) - Meatfrom mature coconut Meat from drinking coconut Milk from green coconut Pandanus, edible portion Arrowroot 89 75 116 79 58 B Ca content, me/g 0.075 0.60 0.13 Crabs, land 14 4.00 Total 6.7 10.5 17.4 11.9 2.10, 45 139 45 Ca intake,mg 0.14 0.15 0.15 Breadfruit Fish Clams AXB Daily 4.00 © 660 121.8 D Fraction oftotal Caintake** ~ 9.008 0.013 0.022 0.015 0.152 27.0 18.1 0.03+ 0.023 36.0 0.070 ” 449 0.36 a 180.0 0.225 E Sr? content, puC/gCa DXE Contribution to total daily Srintake, pyuC/g Ca 1,200 9.6 210 1,000 930 2.7 22.0 14.0 19 2.3 260 280 5 (4,000) ( . 8.8 6.4 Lt (280.0) 67.5 The diet also included imported foods: rice, canned C rations, flour, tea, milk, salt, and sugar. [ORESet Ge gera es *Based on average daily diet of 14 Rongelap males. *” ** Based on total calcium intake of 0.8 g/day.