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."

How Much Harm? Coming from the AEC, Dunham's estimate of the menace of fallout was as official as any could be. But truth is that no one knows what concentrations of radioactive substances actually cause damage, since the world has had less than 15 years' experience of the explosive atom. As the week progressed, other witnesses proved less gloomy. The National Cancer Institute's Lloyd Law said he thought that strontium 90 deposited internally was "relatively ineffective" in production of leukemia; and another scientist said that present fallout levels "are about as likely to produce leukemia in an individual as two cigarettes a year to produce lung cancer.'' And the AEC's own advisory committee reported that fallout to date has contributed less than 5% of the total radiation to which the average person is normally exposed through cosmic rays, other background sources, and medical X rays. "The amount of strontium 90 which has been found in food and water is less of a hazard than the amount of radium normally present in public drinking-water supply in certain places in the U.S., and in public use for many decades."

At week's end a witnesses' panel agreed that the present hazard is "extremely small," not only from strontium 90 but also from the fission products that might damage human genes. But the panel foresaw "serious trouble" for the future if testing continues.

The International Commission on Radiological Protection has settled on 67 strontium units as the "maximum permissible concentration"--beyond which damage could be expected to result. If pollution of the atmosphere continues at the present rate for 40 years, the panel warned, the average concentration in the bones of all the world's inhabitants would reach 56; in northern latitudes the figure would be 64. But Japanese and other Eastern peoples who live in those latitudes ingest more radioactive strontium than Westerners because their diet is based on rice, which grows in calcium-poor soil and takes up strontium 90 to replace the lacking calcium. Their bones Will be carrying an average of 80 strontium units--well above the "maximum permissible concentration."

Steadily harassed by Laborites who think fallout might-contain votes as well as strontium go ("It's a fight for YOUR life," cawed the Daily Herald last week), Britain's Prime Minister Harold Macmillan put before the House of Commons a report prepared by the Atomic Energy Authority and the Medical Research Council. The rate of deposition in rainfall has doubled in the past year, but government scientists are not worried. "The irradiation of human bone and bone marrow attributable to strontium 90," the report concluded, "is at present small in relation to that from the natural radioactivity to which they are exposed."

In debate, Macmillan pointed out that of all radiation to which a man is exposed. 100 units come from natural causes, 22 from man-made sources such as X rays and luminous watch dials, and at most only two from fallout.

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