Radioactivity in Total Diet

Abstract

Total diet samples collected in 1961 from 10 to 25 major cities were analyzed for radionuclides arising from nuclear debris (Sr⁹⁰, Cs¹³⁷, Ce¹⁴⁴, Pu²³⁹, Zn⁶⁵), for natural radioactivity (Ra²²⁶, Pb²¹⁰, K⁴⁰), and for the stable nuclides of Ca and K. The variability arising from collection of samples was not greater than that due to analytical procedures. Levels of Sr⁹⁰ in the total diet ranged from 2 to 15 µµc/gm of Ca. Values in the West, with the exception of the Far Northwest, tended to be lower, but no marked differences were observed among other geographical regions. The Sr⁹⁰/gm Ca values for adult diets, presumably because of their lower milk content, were higher than for infant and teenage diets. The values of Sr⁹⁰/ gm of Ca for the total diet were about 1.6 times those for the milk contained in the diet. It was calculated that 54% of the total Sr⁹⁰ intake came from dairy products, on the assumption that 75% of the Ca originated from this source. The daily intake of Ra²²⁶ was estimated to be about 2 µµc in teenage and adult diets, and about 1 µµc in infant diets. Average daily intakes of the various radionuclides expressed in micromicrocuries, were as follows: K⁴⁰, 4,000; Cs¹³⁷, 50; Sr⁹⁰, 10; Ce¹⁴⁴, 4; Pb²¹⁰, 4; Ra²²⁶, 2; Pu²³⁹, 0.1.