Within biotic community’s ana ecosystems, these radioactive elements may become dispersed or accumulated, depending upon the biological activity of the element and period of radioactivity of the isotope. Strontium-90 for example, normally occurs in radioactive fallout, has a half-life of 28 years and behaves like calcium in biogeochemical cycles.
Thus it is absorbed by plants, invested by animals and deposited in bone tissues close to blood forming tissue. Strontium-90 can also concentrate in natural biological systems following method: water > bottom sediments > aquatic plants > fresh-water clams > minnows and small fish > musk rats.
It is demonstrated that due to this food chain musk rats concentrate strontium-90,3500 times above the levels of the water in which they I’ve. Grazing animals concentrate strontium-90 by ingesting it through grass and forage, and it can then be passed on to humans through milk.
Radioactive phosphate cesium and iodine-132 can also readily accumulate in plants and animals through natural food chains. However, in food chains involving arthropods radioactive isotopes of potassium, sodium, and phosphorus accumulate, but isotopes of strontium and cobalt do not.
Although isotopes may accumulate in human tissues as well as those of plants and animals, it is not established at the gresent time whether current levels of isotopes in human tissues represent serious health hazards to man (Southwick, 1976; Smith, 1977).
Some medical scientists such as Gofman and Tamplin (1970) and Stern- glass (1972), however, feel that man’s radiation exposure from artificial sources is already sufficient to produce serious disease problems (leukemia and bone tumors), genetic damage, and infant mortality.