Nutrition in Relation to Problems of Radioactivity

Basic principles relating to radioisotopes are explained for the physician, preliminary to a discussion of the significance of fallout radionuclides in pediatric nutrition. After a consideration of factors that bear on the amount and composition of fallout products, and those factors that concern their metabolism by the body, it is concluded that for practical purposes only the following isotopes are of biological significance: Sr/sup 89/, Sr/sup 90/, I/ sup 131/, and Cs/sup 137/. Ot her factors that govern the pattern of fallout and that bear on the possible biological hazard are discussed: amounts produced by nuclear bombs, physical half life, rate and location of terrestrial deposition, efficiency of transfer through the food chain to man, absorption and retention by the body, and distribution within the body. Dietary surveys reveal that the intake of Sr/sup 90/, expressed on a per g Ca basis, does not differ appreciably among infants, teenagers, and adults. The average value is about 15 mu VC/g Ca, with values somewhat lower on the West coast than in the East. Evaporated milks have about the same content as that of fluid whole milk, and the content of prepared infant foods does not differ significantly from that of analogousmore » foods eaten by adults. Instant tea and coffee have a high content of Sr/sup 90/ and Cs/ sup 137/, and many other fission products, such as Zr/sup 90/ and Ru/sup 106/. Whole-wheat flour has more Sr/sup 90/ by a factor of four than does white flour; the content of leafy vegetables exceeds that of root vegetables by a factor of 10. Fish have a low content because of the large dilution of fallout by water. Human milk contains only about 1/10 as much Sr/sup 90//g Ca as the mother's diet. Thus the lactating woman provides a discrimination factor, from diet to milk, just as does the cow. Soybean formulas for infants contain only 1/4 as much Sr/sup 90/ as powdered milk formulas, due to addition of uncontaminated Ca during processing. Strontium-90 content of milk collected in the New York City Area during the past seven years is discussed. Although a large share of the dietary Sr/sup 90/ comes from dairy products, total intake is higher in populations whose dietary Ca is largely from nonmilk sources, due to the discrimination factor provided by the cow. Thus, skeletons of rice-eating peoples accumulate 4 times as much isotope as those of milkdrinkers. Measures to reduce fallout exposure are discussed. Washing, peeling, shelling, or removal of the outer leaves of fruits and vegetables will remove much of the external contamination. A portion of the I/ sup 131/ of milk can be removed by aeration. A 90% reduction in other nuclides can be achieved by treatment with ion-exchange resins. Some recently marketed infant formula products contain amounts of Sr/sup 90/ too small to be detected. For short-lived isotopes, such as I/sup 131/, storage allows for dissipation of much activity. With the exception of thyroid blocking with KI, the magnitude of the response to various proposed prophylactic procedures is only 2- to 4-fold; some of them are inherently hazardous, and some are not applicable on a wide scale to man. At present it may be possible to reduce the fission product intake of infants to a certain extent (perhaps by a factor of 5 to 10) by means presently available. The feasibility of accomplishing the same objective in older children on a wide scale is less certain. The remote possibility of introducing new health hazards by the use of procedures aimed at decontamination of foods or diminishing the body burden should always be considered, particularly if large-scale operations are contemplated. It is concluded that the amount of radiation contributed by fallout from weapons testing is only a small fraction of that delivered to the population by other man-made sources. The biological risk from fallout is an exceedingly small one, but is nevertheless of concern to the pediatrician, since children have a much longer life expectancy and will contribute more to the future genetic burden, whatever this may be, than the adult. (BBB)« less