Average Sr⁹⁰ in U.S. milk—measured in trillionths of a gram per quart.
Average radiation doses from Sr⁹⁰ in bones of young children (U.S.)—measured in roentgens per year.
The actual amounts of Sr⁹⁰ in the soil, in the milk, and in the bones of young children are only approximately known. But the main point that we are trying to illustrate, is that since 1954 the buildup of Sr⁹⁰ has gone on at a rather steady rate. How far will this buildup continue?
More radioactivity was released in tests in the year 1954 than in all other years put together. Probably more than one-half of that activity has already been deposited. Since that time the fission energy produced in U.S. tests has steadily decreased. Furthermore, we have learned how to minimize the world-wide fallout by employing ground bursts which deposit most of their activity in the close-in fallout near the test site. It is also possible to place chemical additives near the bomb in order to convert the strontium into a more insoluble form or else into a form which will more readily fall out in the immediate neighborhood of the explosion. And what is most important—we are developing clean nuclear weapons, which produce blast and heat but greatly reduced radioactivity. In the future these clean weapons may eliminate the additional radioactivity altogether.
It is hard to make predictions about the plans of all nations. If we find—and others also find—that clean weapons are the most desirable, the total strontium contamination is not likely to become more than perhaps two to four times the present value. We believe that all reasons—respect for human life, military considerations and simple sanity—lead to one conclusion. In the development of nuclear explosives we must endeavor to make them clean. But the real reason for this does not lie in the small contamination due to tests. The real reason is that war could turn contamination into a danger to countless people.
CHAPTER XII
Danger to the Individual
How much harm is being done by the atomic tests? Some scientists have claimed that from past tests alone about 50,000 persons throughout the world will die prematurely. There is no general agreement on this point. Some think the number should be smaller. It is possible that radioactivity produces some effects which prolong life rather than shorten it. But even if all the biological consequences of radiation were known many questions would still demand answers. Can tests be justified if they actually shorten some human lives? Even the possibility of a health hazard must be taken most seriously. On the other hand: Are there any reasons which make continued testing necessary?
We shall return to these questions in a later chapter. First, however, we shall try to put before the reader the known facts about the fallout danger to the individual. We shall try to put this danger into perspective by relating it to other more familiar dangers to which all of us are exposed. In the following chapter we shall discuss how the fallout may affect future generations.
The dangers from big doses of radiation are well known. Exposure to a thousand roentgens over our whole body causes almost certain death in less than thirty days. Four or five hundred roentgens give a fifty-fifty chance of survival. At less than a hundred roentgens, there is no danger of immediate death. Three years ago the Marshallese got a dose of 175 roentgens. None died. Apparently all are in good health.