Current Strontium-90 Level in Diet in United States

Measurements were made of the concentration of strontium-90 found in approximately 100 food samples collected throughout the United States. Samples of important calcium sources such as milk, vegetables, cereals, and tap water were includcd. From an analysis of the data it is concluded that the strontium- 90 conient in ihe dlet of an average United States citizen in 1957 was about 6.5 Sunshine Units. corresponding to an equilibrium base level of 1.5 Sunshine Units, since the discrimination factor belween diet and base appears to be about 4. If the diet concentration remains constant for a decade. the equilibrium bone level of 1.6 Sunshine Unit would be approached by young children. New-born children would have about half of this value on account of fetal discrimination, and adults would reach only 20 to 30 percent of the equillbrium level, because of the slow rate of exchange of calclum in bone. (C.H.)