Reprinted from ScIENCE, August 3, 1958, Vol. 128, No. 3318, pages 256-257. Common Strontium Content of the Human Skleton The geochemica and biogeochemical behavior of the dement strontium is important in undestanding the movement of fission-procict strontium-90 into man (7). Several investigators (2, 3) have analyzed hunan bone from different locations for srontium, The availability of a large collection of bones from the study of torld-wide fallout of strontium-90 made convenient the examination of this frameter in greater detail. This report ¢) is concerned with (i) the distributionof strontium among the different bone in an individual skeleton, (ii) the «stribution of strontium in the populaion of a single city, and (iii) the extesion of information on geographical vziation. Samples consisted of a variety>f bones from eleven individuals, wholekeleton ash from 133 NewYork City caavers, and composites from 16 localiti, each representing equal weights of tne ash from 4 to 38 individuals. The analyses we performed by an emission spectrognhic technique modified from that o'Turekian and Kulp (2), The standan used to define the working curves we actual samples of bone ash which #re analyzed by the isotope dilution ethod (accurate to within 5 percent) \ll samples were run in duplicate and-e reported as parts of strontium per rion. The reproeducibility of these aryses is estimated to be about + 10 perat. The average strtium content of ad- ditional samples fn previously investi- gated areas (2) waound to be about 30 percent lower. In cer to check this discrepancy, some ofte original samples were reanalyzed the present method. The new analysesere also about 30 percent lower m ch case. Synthetic standard: similar those used by Tu- rekian and Kulp’) were analyzed, using the present sking curve defined by isotope dilution alyses of bone ash, The results indicathat a matrix difference between bs and chemically precipitated phosp! is responsible for the higher values reted in the carher work (2 In view this observation, the samples of Turn and Kulp were composited by ety and redeter- mined. The distribution of commenstrontium among the different bones of individuals was examined by analyzing the femur, tibia, fibula, humerus, u!na, radius, hand or foot bones, skull, pelvis-sternum, vertebrae, ribs, clavicle, scapula, and kneeelbow from eleven skeletons (5). Although the average strontium content of the whole skeleton varied by a factor of 3 among these individuals, there was no systematic difference in strontium content between any two bones of the body outside of the experimental error (stand- Table 1. Worid survey of common strontium in human bone. : Location Boston Boston Boston New York Houston Houston vo. of amples samp Sr in bone ash ppm North America 37 38 62* 134* 14+ 12 Av 101 109 117 162 125 190) 162 152 ~ 105 Denver 337 203 203 Vancouver Vancouver San Juan 17} 12 5+ 164 117 i79 14 179 Guatemala 29 156 156 Recife South America 344 344 Guayaquil 17 oT i79 179 Cordoba 18 160 160 Santiago 37t 160) 160 187 Santiago a4 160 Caracas 377 187 West Germany Copenhagen Copenhagen Europe 307 137 137 2T 4 242 256 253 140 Zurich ly 140) Rome OF 168 Rome London London 10 4y 21 Ava Tokyo Tokyo Tokyo ‘Taiwan 36 21% at 19+ India ait Taiwan India Durban Liberia World av 6 12 Africa 13 1 258 187 136 206 199 23 191 179 176 206 160 ard deviation of 10 percent). Thus a single bone can give a valid estimate of the common strontium content of the body at this level of certainty. This would also be the case for strontium-90 distribution if a population ingested a diet . 18; . “14 187 194 324 195 324 172 * Samples run individually, ¢ Samples reported by Turekian and Kulp (2) rerun as composites. a constant Sr®°/Ca_ ratio uals. The histogram (Fig. 1) of the stron- tium concentration in 133 individuals (whole skeleton ash} from New York City shows a nearly normal distribution with a standard deviation that is only about +32 percent of the mean of 162 parts per million by weight. The narrow spread reflects the averaging of food sources In a city environment, The data on the concentration of strontium in human bone in various geo- graphical localities are summarized in Table 1. To show that the use of com- posite samples is valid, the samples from Boston and Tokyo were run individually, and then equal weights of bone ash were combined into composite samples. There appear to be small but significant differences from one locality to the next, The average for any given locality falls within a factor of 2 of the mean of the data (172 ppm). Recent work by Sow- den and Sutch (6) on a limited number of samples from England analyzed by neutron activation gives results which are consistent within the experimental] and natural variation of those reported here. Their work shows a Jower strontium concentration in young children. This is expected as a result of fetal discrimination against strontium (7). An examination of the present analyses shows that for adults there is no age effect, The average world-wide value of (%Sr)/(%Ca) x 10% in human bone derived from Table 1 is 0.45+0.1. The value 206 with throughout the lifetime of the individ- (%Sr/%Ca} x 10% in average rock or soil is 7+ 1 (8). The discrimination factor between soi! and skeleton for the strontium/calcium ratio is therefore 1522. The experimentally determined discrimination factor for strontium/caleium between soil and plant is about unity (9), between plant and milk, about 7 (10), and between milk or vegetation and human boneit is about 4 (73. Thus, if in the average urban world population, half of the calcium in the diet comes from milk, and half from poe ARCHIVES