itself.

School of surgeonfish off Arji Island, Bikini Atoll, August 1964. Note coral growth on lagoon bottom.

Wide-ranging studies of ocean-borne radioactivity were initiated by the Japanese. The experience of the fishermen produced in Japan a fear of contamination of fisheries resources as a result of the United States tests. One result was the organization, in the summer of 1954, of a government-sponsored ocean survey expedition that cruised from Japan into and through the Bikini-Eniwetok area to determine what amounts of radioactivity were being carried, by water and by aquatic organisms, toward the shores of Japan.

The expedition made significant observations of the role of plankton[10] in the biological utilization of ocean fallout. A United States scientific team, following up the Japanese effort, made a similar but far more extensive cruise through the Western Pacific early in 1955 and went on to Japan to discuss its findings with the Japanese. During and after the test series in the Pacific in 1956 and 1958, United States surveys of the ocean were made routinely. Exchanges of information between scientists of Japan and the United States continued.

The Rongelap case produced results of another kind. The Rongelap people were found to have suffered exposure requiring medical attention and continued observation. Evacuated from their atoll because it was not safe, members of the community were given care at other atolls until they could be repatriated in 1957, and received continued medical supervision thereafter.

The bioenvironmental condition of Rongelap was unique. The fallout had made the atoll the only place in the world contaminated on a single occasion by relatively heavy deposition of radioactive debris without also being disturbed by a nuclear explosion. In 1957-1958, after the Rongelapese had been returned to a new village constructed on their atoll, Rongelap was the site of a long and thorough study of the circulation of radionuclides in the terrestrial-aquatic environment.

Before the 1963 Test Ban Treaty

The first break in the pattern of nuclear testing came in 1958, when the nuclear powers agreed to a 1-year test moratorium. The world’s political and emotional climates were changing. For more than 5 years, the United States, which had announced its Atoms-for-Peace Program in December 1953, had been endeavoring to place emphasis on the use of atomic energy for constructive purposes. The Atomic Energy Act of 1954, liberalizing provisions of the 1946 law, contemplated for the first time private development of nuclear power resources and established authority for international activities. In 1957 the Atomic Energy Commission initiated its Plowshare Program for the development of peaceful uses of nuclear explosives.[11]

Distribution of fallout radioisotopes on Rongelap Atoll as determined by a survey in 1961. Note the interrelationships of man, plants, animals and the environment.

Amid such changes there was arising, too, a wider apprehension concerning the possible effects of fallout. The United Nations in 1955 appointed a committee of scientific representatives of 15 nations to study the effects of radiation on man. In the United States the National Academy of Sciences published in 1956 the first of its summary reports on the biological effects of atomic radiation.

Nuclear testing was not ended by the 1958 agreement, yet the moratorium—which was renewed annually until 1961, when the U.S.S.R. broke the agreement by initiating a new test series—was significant as an experiment in nuclear restraint. After the United States conducted a final test series near Christmas Island in 1962, new discussions of ways to halt successive rounds of nuclear test programs were held. Finally, in 1963, the Nuclear Test Ban Treaty was signed by most of the nations of the world. The treaty was, among other things, a declaration against worldwide fallout.

THE ATOM IN ENVIRONMENTAL STUDIES

Although his experience with radioactivity has been brief, man probably already knows more about the effects of radiation than he knows about the effects of many other contaminants that alter his environment. Even so, he knows far less than he needs to know to make certain that atomic energy is wisely managed in the future.

There has been neither time nor opportunity, for example, to gather radiation-effects data on more than a few hundred of the 1,500,000 kinds of living organisms inhabiting the earth. Nor is it possible to predict the extent to which life can adjust itself to environmental changes resulting from scarcely perceptible alterations of natural radiological balances. Also undetermined is the relation between environmental changes and the biological exchanges making up the often mentioned, but insufficiently understood, “balance of nature”.

The case of carbon-14 is an example of a permanent man-made modification of the environment. From the early ages of the earth, carbon-14 has been created in the upper atmosphere by the transmutation of nitrogen in cosmic-ray reactions. Carbon itself is an almost universal component of living matter, and the ratio between stable carbon and radioactive carbon is believed to have been unchanged for thousands of years. It is this circumstance that permits the use of carbon-14 as a tool for “dating”, or determining the ages of, fossil remains, prehistoric artifacts, and geologic formations. But carbon-14 also is produced in nuclear fusion, and the testing of thermonuclear devices after 1952 produced an estimated increase of 4% in the amount of carbon-14 on earth. This is enough to disturb the natural equilibrium. Since the half-life[12] of carbon-14 is some 5800 years, the addition will be a factor of environmental consideration for scores of human generations.

Nuclear tests, although not the only sources of man-made radioactivity, have been until now the most significant ones and the only sources touching large areas of the earth. The total product of nuclear testing is small in relation to the natural burden of radioactivity, raising the level of radiation to which all life is subject by a factor of one-tenth or less. But it is the unknown element, the degree to which fallout radioactivity may introduce new influences into the environment, that gives concern.[13]

One of the last cows of the herd exposed to fallout by the world’s first atomic detonation in New Mexico in July 1945, photographed in 1964. The calf is her 15th to be born in 15 years. The cow, believed about 20 years old, has been under observation by scientists, who found she suffered little