Part 7

Contrary to all expectations, however, the original colony had not been eliminated. Biologists visiting Engebi in 1953 and 1954 found the rats apparently flourishing. New generations of rats were being born and were subsisting on grasses and other plants in an environment still slightly radioactive. In 1955 analysis of the bones of rats revealed the presence of strontium-89 and strontium-90 in amounts approaching what was assumed to be the maximum amount that would not cause bodily harm. The rats’ muscle tissues contained radioactive cesium-137. But no physical malformations were found in the rats. All animals appeared in sound physical condition, despite these body burdens of radioactivity. By 1964 the rat population had so increased that it apparently had reached equilibrium with available food supplies.

Questions relating to the reestablishment of the colony are intriguing. Why are new generations of these warm-blooded animals continuing to thrive after the colony was exposed to devastating nuclear effects? Is there a different dose-effect relation for these rats than for other animals? Even if it is assumed, as it must be, that some members of the colony survived the original nuclear heat and radioactivity because they were shielded by concrete bunkers or other man-made structures, how is it that there have been no observable effects among rats existing for years in an area that continually exposed them to radiation?

Fallout and Populations

In Arctic regions lying on opposite sides of the North Pole, fallout has created conditions that are given continuous scrutiny by scientists of Scandinavia and the United States.

The two cases, one involving the Lapps of northern Finland and the other the Eskimos of Alaska, are essentially the same. Hemispheric fallout introduced quantities of long-lived radionuclides, particularly cesium-137, into the food chains and consequently into the diets of native peoples. In each instance there had occurred a slow accumulation of radionuclides in the lichens and mosses and in other plants that are the foods of the reindeer and caribou. The meat of these animals forms a substantial part of the human diets, and as a result the members of the native communities were found to have, on the average, body burdens of radioactivity approaching the acceptable limit for human populations.

A preliminary study of the Lapp environment was made in 1958-1959, and a Lapp dietary study was made in 1960. The results showed close correlation between the consumption of reindeer meat and the Lapps’ body burdens of cesium-137. The Scandinavian investigators concluded that the levels of concentrated cesium approximated the maximum permissible dose range for large populations. They noted, however, that “the final answer ... has to be given by the geneticists”.

In Alaska, where studies of the native populations have been proceeding for several years, adult Eskimos living in the vicinity of Anaktuvuk Pass were found in 1964 to have average body burdens of cesium-137 more than 20 times as great as the average for adults in the area of the original 48 states. There was an expectation that even without further nuclear testing the levels of cesium-137 would continue to rise slowly in Arctic regions until about 1968.

The Variety of Approaches

Bioenvironmental studies form a background against which all atomic energy research is conducted. The central objective of the Atomic Energy Commission’s environmental radiation studies is “to determine the fate and effect of radionuclides in the environment”. This objective calls for hundreds of concurrent approaches to the interlocking problems of the air, the sea, and the land. The AEC alone, through its Division of Biology and Medicine, is supporting research costing about $75 million a year, about two-thirds of this amount going to biological and medical programs at AEC laboratories and the remainder to some 650 individual contract studies at universities, nonprofit institutions, and commercial research organizations. Additional programs, large and small, are supported by foundations or other agencies. Work goes on in other nations. Many programs are international. Although only a fraction of this total activity is specifically related to environmental problems, the concern throughout is with the effect, for good or ill, of radioactivity on man and his world. It is possible to suggest by example the lines of inquiry.

The Trinity site in New Mexico, scene of the first atomic detonation in history, was studied for a number of years after 1945, particularly in relation to the distribution and effects of residual radioactivity in the desert environment. In 1963 and 1964 scientists from the University of Missouri undertook to determine the state of revegetation of the original atomic bomb crater.

The Nevada Test Site, where nuclear programs have been conducted for a decade and a half, has invited investigations of revegetation. Project Sedan, an underground thermonuclear detonation in 1962, established conditions for one such study. The crater produced by this detonation was 320 feet deep and 1200 feet in diameter. Vegetation growing within 2500 feet of ground zero was almost completely destroyed, and the original soil was covered by radioactive throwout. Shrubs as far as 5000 feet away from ground zero were damaged by air blast, and, in the weeks after the detonation, plants within a two-mile radius were covered by radioactive sand and silt or by deposits of windblown radioactive dust.

Studies in 1963 by scientists from the University of California at Los Angeles showed that native plants—Russian thistle and various annuals—had become well established in the zone around the Sedan crater where the earth was thrown out. This area had remained barren for less than a year. Some of the shrubs most severely damaged by the blast, and exposed to cumulative gamma radiation doses of more than 4000 roentgens, had produced new growth. Populations of creosote bush, evergreen plants that in 1962 appeared to have been killed by heavy doses of radiation, were producing leafy branches in the summer of 1963. These developments permitted no conclusions, of course, for the possible radiation effects still needed to be identified. Studies were conducted, for example, of the effect of deliberately depositing nonradioactive dust on healthy creosote plants, and comparative studies of other phenomena were made.

Since 1959, ecological studies have been carried forward at the Nevada site by investigators from Brigham Young University who are interested in the abundance, seasonal occurrence, and ecological influences affecting the vertebrate and invertebrate animals in plant communities of the region. Surveys have been made in areas where nuclear explosions had obliterated natural ecological relationships and in similar areas undisturbed by nuclear effects. The investigations are concerned primarily with desert ecology—with the identification of biotic communities and of predominant animal species.

Among research programs in marine environments is that initiated in 1963 and 1964 by the University of California’s Institute of Marine Resources at La Jolla, where studies of marine food chains are conducted by a team of zoologists, chemists, botanists, and microbiologists. The program studies the interrelations among organisms at the lower levels of the food chains and the dynamics of marine phytoplankton cell division, photosynthesis, and excretion of organic matter as related to temperature, light intensity, and nutrient conditions. The work is conceived as a basic study of marine ecology. It is focused, however, on questions found to be significant in studies of radioactivity in the sea.

The University of California’s Lawrence Radiation Laboratory has launched a long-term investigation of the effects of the release of radionuclides on the biosphere, which encompasses the origins, transport, and final localization of radionuclides in all types of organs, tissues, cells, and subcellular constituents. The objective is “to develop the most complete understanding possible of the potential hazards to man that arise from the release of nuclear radiation and radionuclides into the biosphere and to apply this knowledge to the prevention of damage to living forms...”.

In programs such as these—multiplied by hundreds—the problems are being attacked.

WHERE ARE WE NOW?

Radiobiological studies that are environmental in scope became, with the release of atomic energy, a mandate on the twentieth century.

Environmental studies are not new. They have been implicit in thousands of biological research efforts, large and small, for generations. Atomic energy, however, is a new factor. Also new is the intensity of the approach. Not until the explosion of inquiry of this century has man brought together the necessary resources—the time, the funds, the instruments, the ingenious technological devices, the ideas, and the organizational and management skills—to attack problems that are global in scale.

The atom as a tool of the environmental radiobiologist has, of itself, solved few problems. Its significance is that it has speeded up—to a degree still not fully tested—our ability to study ecosystems and their relations to each other.

The First Twenty Years

Instruments for environmental research.

The first two decades of the Atomic Age have comprised a period of swift maturity. Much has been done to gain perspective. Atomic energy as a potential force for destruction has not been controlled. But there is a surer knowledge of the hazard inherent in the absence of control and a rational hope that the new power will be directed toward peaceful objectives. We know that:

1. The uninhibited release of nuclear products into the environment of the earth will create problems—fundamentally biological problems—of long duration and of still-unassessed ultimate effect.

2. Use of atomic weapons in war could have a “biological cost” beyond calculation.

Yet, in terms of constructive employment of atomic resources, we also know that:

1. Atomic energy may help solve the very problems that the new age presents.

2. Careful and controlled development of atomic forces will provide the reservoirs of energy that will be needed to sustain the world’s populations of the next century and beyond.