Biologists are interested in every kind of living thing. When they study organisms in relation to atomic radiations, they enter the field of radiobiology, which really is not a science in itself but merely a branch of the larger interest in biology. Biologists find that atomic energy has significance both in the study of individual organisms and in studies of organisms in their natural communities and habitats.

Radioactivity introduced into any community may be “taken up” by the biological system, becoming subject to cycling in food chains or to accumulation in plant or animal tissues. The presence of radioactivity permits study of the workings of a system as large as an ocean, perhaps, or of one no larger than a tree. And in each case it thus may be possible to observe how the cycles of organic renewal are related to the larger systems of life on earth.

The Single Environment

The environment in which we live is recognizable as a single complex, composed of many subenvironments—land, oceans, atmosphere, and the space beyond our envelope of air. The deer in the forest, the lizard in the desert burrow, and the peavine in the meadow are different kinds of organisms living in situations that are seemingly unalike. Each creature is part of its environment and a contributor to it, but it also is part of the total biosphere.[1] All creatures are linked to each other, however remotely, in their dependence on limited environments that together form the whole of nature.

We know much about the life of the earth, but there is far more that we do not know. Understanding of the large cyclical forces has continued to elude us. We do not even yet grasp the small and seemingly random biological relations between individual organisms—relations involving predator and prey, for instance, and those among species and families—such as exist together in symbiotic[2] harmony and interdependence. Through centuries of observation we have gained a store of information. We are left, however, with a still unsatisfied curiosity about the reach and strength of the tenuous biological cords that bind together the lives of the deer, the lizard, and the peavine.

The Need to Understand

Life on earth evolved amid constant exposure to ionizing[3] radiation, from the earth itself and from space, known as background radiation. Therefore environmental studies must be conducted in relation to, and with understanding of, background radioactivity.

Of some 340 kinds of atoms that have been found in nature, about 70 are radioactive. Three families of radioactive isotopes[4]—the uranium, thorium, and actinium series—produce a large proportion of the natural radiation. Other radionuclides[5] occur singly, rather than in families, and some of them, such as potassium-40 and carbon-14, are major contributors of natural radioactivity. Traces of natural radioactivity can be found, in fact, in all substances on earth.

When man began experimenting with atomic fusion and fission, he placed in his environment—across vast landscapes, in the oceans, and in the atmosphere—measurable additional amounts of radioactivity. These additions were composed of the longer-lived members of some 200 kinds of atomic radiation. Although the additions constituted but a fraction of the background burden, they represented the first alteration of the radiological balance that had existed since the early ages of the planet. Thus it became necessary to determine what the impact of such a change might be. In the process of inquiry, these ideas emerged:

1. The addition of man-made radioactivity presents the possibility of delayed or cumulative effects. Long-term studies, geared to the assessment of biological effects from extremely low radioactivity, are essential.

2. The addition of radioactivity makes possible broad-gauged studies to trace the movement and concentration of radionuclides in the environment. These studies, in turn, can disclose new information on biological complexes and mechanisms.

The quantities of low-level long-lived radioactivity already released into our environment will provide materials for future studies covering decades. Further, because radioisotopes are chemically similar to nonradioactive forms, observation of their biological fate will provide clues to the transport, concentration, dilution, or elimination of many other kinds of man-made toxic agents and contaminants of the environment.

Operating Concepts

Environmental problems are best approached in the environment itself, where all the natural variables and unknowns are present. Laboratory work is essential, but no laboratory can carve from nature or reproduce artificially all the complexities of the natural environmental “laboratory”, the ecosystem.[6]

Environmental studies frequently demand the coordinated attentions of ecologists,[7] chemists, physicists, geologists, oceanographers, meteorologists, botanists, zoologists, and others, all working together to approach the environment as a synchronized mechanism.

Finally, environmental studies are conducted with a special consciousness of the need to withhold judgment as to what is meant by “effect”, particularly “radiation effect”. Gross, immediate effects may be determinable. Ultimate effects may be generations in the making, remote in time and space from their causes. Studies thus are focused on biological processes and on isolation and identification of the long-range trends.