Word: strontium
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Walter Selove, professor of Physics at the University of Pennsylvania and formerly assistant professor of Physics here, took a rather different viewpoint of the situation. He pointed out that it is virtually impossible to determine what may be reasonably called a "permissible level" of radioactive strontium 90 in the body...
When any kind of strontium gets into soil, it is taken up by plants as if it were calcium. Since plants do not like it as much as calcium, those grown in calcium-deficient soil generally contain more strontium 90 than plants that get plenty of calcium. It is not established, however, that all plants behave in this...
Cows & Grass. When animals, including milk cows, eat plants containing strontium 90, they reject it selectively in favor of calcium. Therefore milk contains less strontium 90 in proportion to calcium than the grass or alfalfa that the cows eat. This means that humans who get most of their calcium from milk will collect less strontium 90 than people who get their calcium direct from vegetable sources...
Most of the strontium 90 created by past bomb tests is still in the stratosphere or in the soil, but it will tend to move for years into human bones. If no more large tests are made, the Columbia men figure, the average human bone should contain, by 1970, about 1.3 micromicrocuries of strontium 90 per gram of calcium. This is eleven times the present amount...
...Columbia men are concerned about such individuals as the Vancouver man who have a lot more strontium 90 than the average, and about people who get most of their calcium from vegetables that were grown in calcium-deficient soil. Such people may come much closer to the "permissible" level. The permissible level itself is still considered debatable. It was derived principally from a small amount of experience with the cancer-causing effects of radium in the bones; at that time no strontium 90 existed in the world. When more is known, the permissible level for strontium 90 may have...