Science: The Problem of Fallout

How serious is the threat presented to man by fallout—the radioactive debris that settles invisibly over the earth after test explosions? Reactions range from unconcern to the near side of panic. Alarmed by recent announcements of sizable fail-out increases over North America since the U.S. and Soviet nuclear tests in October, a subcommittee of the Joint Congressional Committee on Atomic Energy held hearings last week, listened to scientists' reports addressed to two pivotal questions: How much of fission's byproducts —notably strontium 90, which enters the body in food, accumulates in the bones and may cause leukemia and bone cancer —can the human body safely tolerate? How much has been injected into the air and at what rate is it coming down?

Few can speak with equal authority on both subjects, since agencies that are responsible for the development of atomic weapons (AEC, Department of Defense) have different objectives from groups that are concerned primarily with the control of disease (e.g., the Public Health Service). Nonetheless, the scientists found agreement in several areas: fallout patterns vary in different parts of the world; debris comes to earth more rapidly than was once thought. And some new information was made public.

How Much Debris? AEC Biology and Medicine Director Charles L. Dunham, first to testify, carried a thick sheaf of papers that contained the biggest news of the hearings. Since 1945, Dunham revealed, the world's three atomic powers have exploded bombs with a total fission yield of more than 91,000 kilotons. The U.S. and Britain have been responsible for more than two-thirds of it. But the Russians contributed 21,000 of their 25,560-kiloton total in 1957-58 alone, raising the debris in the stratosphere to a record level.

By force of geography, Russian test explosions are in northern latitudes. Evidence was presented that fallout from Soviet polar shots is caught in the downward drafts of arctic air and delivered to earth quite rapidly (in about a year), while debris from equatorial explosions probably stays up longer. Largely as a result of Russian polar shots last year, twice as much strontium 90 fell on the U.S. as in any previous year.

The total amount of strontium 90 released to date, said Dunham, might result in 150 to 300 cases of bone cancer and leukemia in the U.S. each year from now until the year 2029—a figure he put in perspective against the 98,000 expectable fatalities caused in the same period by "other aspects of our defense efforts."