DISTRIBUTION OF RADIOACTIVITY IN FOODS
By far the largest fraction of the radioactivity present in foods is due to the naturally radioactive element potassium. The average American ingests about 2300 pC of K/sup 40/ per day and this nuclide, with a half life of more than a billion years, distributes itself through the body, and on the average delivers a dose that is about 20% of the dose received from ali natural sources. Other radionuclides that occur naturally ia all foods are C/sup 14/ Ra/sup 126/, Ra/sup 228/, and uranium. In some places in the world the radium content of food and water is known to be abnormally high. About half a million people in the Middle West consume water in which the radium content is more than ten times normal. Recent studies in Brazil have shown that foods grown in certain areas known for their high radioactivity contain radium and mesothorium in amounts that are 10-30 times normal. Of the many isotopes produced in fallout, Sr/sup 90/, Sr/ sup 89/, Cs/sup 137/, and I /sup 131/ are the most significant insofar as contamination of food is concerned. Beginning with the first test of nuclear weapons, the Sr/sup 90/ content of foods began to increase and records of the amount of Sr/sup 90/ in foods have been maintained by several agencies since 1954. The concentration of this long-lived isotope increased until early 1959 when it began to decline, following the temporary moratorium of weapons testing. American children receive most of their Sr/sup 90/ from fresh milk but this is only because fresh milk happens to be the principal source of dietary calcium. Children who receive their calcium from food other than milk would absorb more Sr/ sup 90/ because the cow eliminates much of the Sr/sup 90/ in the process of producing milk. Sr/sup 89/ behaves like Sr/sup 90/ except that it is short-lived and does not accumulate. Cs/sup 137/ is also long-lived, has characteristics somewhat like potas sium, but does not accumulate in foods to the same extent as Sr/sup 90/ because it tends to be locked into the soils in such a manner as to be unavailable to plants. During periods of weapons testing the amounts of radioiodine (I/sup 131/) in milk exceeds that of any other radioisotope. Although traces of this nuclide may be found in other fresh foods, the amounts are insignificant compared to that observed in cow's milk and to a lesser extent in cottage cheese. (auth)
- Research Organization:
- New York Univ., New York
- NSA Number:
- NSA-18-003605
- OSTI ID:
- 4142077
- Journal Information:
- Federation Proc., Vol. Vol: 22; Other Information: Orig. Receipt Date: 31-DEC-64
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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