A DOSE OF NUCLEAR RADIATION

Lovelock, James: The Ages of Gaia (1988)

Carl Sagan once observed that if an alien astronomer were to look at the Solar System in the radio-frequency part of the spectrum, it would see a truly remarkable object. Two stars eclipsing one another: one of them a normal, small, main-sequence star and the other a very small, but intensely luminous body with an apparent surface temperature of millions of degrees, our Earth. Were that distnat observer a scientist, it might speculate on the nature of the energy source that powered, what seemed to be, one of the hottest objects in the Galaxy. I wonder how high on the list of probable sources it would place chemical energy. Would it include energy coming from the reaction between fossil fuels and oxygen from plants?

It is easy to ignore the fact that we are the anomalous ones. The natural energy of the Universe, the power that lights the starts in the sky, is nuclear. Chemical energy, wind, and water wheels: such sources of energy are, from the viewpoint of a manager of the Universe, almost as rare as a coal-burning star. If this is so, and if God's Universe is nuclear-powered, why then are so many of us prepared to march in protest against its use to provide us with electricity?

Fear feeds on ignorance, and a great niche was opened for fear when science became incomprehensible to those who were not its practitioners. When X rays and nuclear phenomena were discovered at the end of the last century, they were seen as great benefits to medicine--the near-magic sight of the living skeleton and the first means to palliate, even sometimes cure, cancer. Röntgen, Becquerel, and the Curies are remembered with affection for the good their discoveries did. Sure enough, there was a dark side also, and too much radiation is a slow and nasty poison. But even water can kill if too much is taken.

It is usually assumed that the change in attitude towards radiation came from our revulsion at that first misuse of nuclear energy at Hiroshima and Nagasaki. But it is not that simple. I well remember how the first nuclear power stations were a source of national pride as they quietly delivered their benefice of energy without the vast pollution of the coal burners they replaced. There was a long spell of innocence between the end of the Second Worlds War and the start of the protest movements of the 1960s. So what went wrong?

Nothing really went wrong, it just happens that nuclear radiation, pesticides, and ozone depleters share in common the property that they are easily measured and monitored. The attachment of a number to anything or anyone bestows a significance that previously was missing. Sometimes, as with a telephone number, it is real and valuable. But some observations--for example, that the atmospheric abundance of perfluoromethyl cyclohexame is 5.6 x 10-15, or that as you read this line of text at least one hundred thousand of the atoms within you will have disintegrated--while scientifically interesting, neither confer benefit nor have significance for your health. They are of no concern to the public.

But once numbers are attached to an environmental property the means will soon be found to justify their recording, and before long a data bank of information about the distribution of substance X or radiation Y will exist. It is a small step to compare the contents of different data banks and, in the nature of statistical distributions, there will be a correlation between the distribution of substance X and the incidence of the disease Z. It is no exaggeration to observe that once some curious investigator pries open such a niche, it will be filled by the opportunistic growth of hungry professionals and their predators. A new subset of society will be occupied in the business of monitoring substance X and disease Z, to say nothing of those who make the instruments to do it. Then there will be the lawyers who make the legislation for the bureaucrats to administer, and so on. Consider the size and intricacy of the radiation-monitoring agencies, of the industry that builds monitoring and protective devices, and of the academic community that has radiation biology as its subject. If the strong public fear of radiation were dispelled, it would not be helpful to their continued employment. We see that there is a very biological, Gaian, feedback in our community relationship with the environment. It is not a conspiracy or a selfishly motivated activity. Nothing like that is neeed to maintain the ceaseless curiosity of explorers and investigators, and there are always opportunists waiting to feed on their discoveries.

If this alone were not enough, there are the media, ready to entertain us. They have in the nuclear industry a permanent soap opera that costs them nothing. Why, we can even experience the excitement of a real disaster, like Chernobyl, but in which, as in fiction, only a few heroes died. It is true that calculations have been made of the cancer deaths across Europe that might come from Chernobyl, but if we were consistent, we might wonder also about the cancer deaths from breathing the coal smoke smogs of London and look on a piece of coal with the same fear now reserved for uranium. How different is the fear of death from nuclear accidents from the commonplace and boring death toll of the roads, of cigarette smoking, or of mining--which when taken together are equivalent to thousands of Chernobyls a day.

It was Rachel Carson, with her timely and seminal book Silent Spring, who started the Green Movement and made us aware of the damage we can so easily do to the world around us. But I do not think that she could have made her case against pesticide poisoning without the prior discovery that agricultural pesticides were distributed ubiquitously throughout the whole biosphere. Number could even be attached to the wholly insignificant quantities of pesticide in the milk of nursing mothers or in the fat of penguins in the Antarctic. In Rachel Carson's time, pesticides were a real threat, and the blind exponential increase of their use put all our futures in hazard. But we have responded in a fashion, and that one experience ought not be extrapolated to all environmental hazards real or imagined.
The foregoing paragraphs are not intended as support for the nuclear industry, not to imply that I am enamoured of nuclear power. My concern is that the hype about it, both for and against, diverts us from the real and serious problem of living in harmony with ourselves and the rest of the biota. I am far from being un uncritical supporter of nuclear power. I often have a nightmare vision of the invention a simple, light weight nuclear fusion power source. It would be a small box, about the size of a telephone directory, with four ordinary electricity outlets embedded in its surface. The box would breath in air and extract, from its content of moisture, hydrogen that would fuel a miniature nuclear fusion power source rated to supply a maximum of 100 kilowatts. It would be cheap, reliable, manufactured in Japan, and available everywhere. It would be the perfect, clean, safe power source; no nuclear waste nor radiation would escape from it, and it could never fail dangerously.

Life could be transformed. Free power for domestice use; no one need ever again be cold in winter or overheated in the summer. SImple, elegant pollution-free private transport would be available to everyone. We could colonize the planets and maybe even move on to explore the star systems of our Galaxy. That is how it might be sold, but the reality almost certainly is ominously expressed by Lord Acton's famous dictum "Power tends to corrupt and absolute power corrupts absolutely." He was thinking of political power, but it could be just as true of electricity. Already we are displacing the habitats of our partners in Gaia with agricultural monocultures powered by cheap fossil fuel. We do it faster than we can think about the consequences. Just imagine what could happen with unlimited free power.
If we cannot disinvent nuclear power, I hope that it stays as it is. The power sources are vast and slow to be built, and the low cost of the power itself is offset by the size of the capital investment required. Public fears, unreasoning though they sometimes are, act as an effective negative feedback on unbridled growth. No one, thank God, can invent a chain saw driven by a nuclear fission power source that could but a forest as fast and heedlessly as now we cut down a tree.

To my ecologist friends, many of whom have been at the sharp end of protest against nuclear power, these views must seeem like a betrayal. In fact, I have never regarded nuclear radiation or nuclear power as anything other than a normal and inevitable part of the environment. Our prokatyotic forebears evolved on a planet-sized lump of fallout from a star-sized nuclear explosion, a supernova that synthesized the elements that go to make our planet and ourselves. That we are not the first species to experiment with nuclear reactors has been touched on earlier in this book.

I am indebted to Dr. Thomas of Oak Ridge Associated Universities, who gave me a new insight on the nature of the biological consequences of nuclear radiation. As I listened to his words, spoken in the quiet privacy of his room, I felt an emotion like that described by Keats in his verses about fist reading Chapman's Homer. What Dr. Thomas said may have been no more than hypothetical, but to me it was exciting stuff. Let's look at his proposition: "Suppose that the biological effects of exposure to nuclear radiation are no different from those of breathing oxygen."
We have long known that the agents within the living cell that do damage after the passage of an X-ray photon, or a fast-moving atomic fragment, are an assortment of broken chemicals; things called free radicals that are reactive and destructive chemicals. As an X-ray photon passes through the cell, the radiation severs chemical bonds just as a bullet might sever blood vessels and nerves. By far the greater part of this destruction is of molecules of water, for they are the most abundant in living matter. The broken pieces of a water molecule form, in the presence of oxygen, a suite of destructive products including the hydrogen and hydroxyl radicals, the superoxide ion, and hydrogen peroxide. These are all capable of damaging, irreversibly, the genetic polymers that are the instructions of the cell. This is now conventional scientific wisdom; the novel insight from Dr. Thomas was to remind us that these same destructive chemicals are being made all the time, in the absence of radiation, by small inefficiencies in the normal process of oxidative metabolism. In other words, so far as our cells are concerned, damage by nuclear radiation and damage by breathing oxygen are almost indistinguishable.

The special value of this hypothesis is that it suggests a rule of thumb for comparing these two damaging properties of the environment. If Dr. Thomas were right, then the damage done by breathing is equivalent to a whole body radiation dose of approximately 100 roentgens per year. I used to wonder about the risk-benefit ratio of a medical X-ray examination. A typical hospital X-ray of the chest or abdomen could deliver 0.1 roentgen of radiation, enough to blacken the film of a personal radiation monitor and to have caused terror to the inhabitants of Three Mile Island. Now, thanks to Dr. Thomas, I look upon it as no more than one-thousandth of the effect of breathing for a year. Or to put it another way, breathing is fifty times more dangerous than the sum total of radiation we normally receive from all sources.

The early battles at the end of the Archean against the planet-wide pollution by oxygen are still apparently with us. Living systems have invented ingenious countermeasures: antioxidants such as vitamin E to remove the hydroxyl radiacals, superoxide dismutase to destroy the superoxide ion, catalase to inactivate hydrogen peroxide, and numerous other means to lessen the destructive effects of breathing. Nevertheless, it seems likely that the life span of most animals is set by a fixed upper limit of the quantity of oxygen that their cells can use before suffering irreversible damage. Small animals such as mice have a specific rate of metabolism much greater than we do; that is why they live only a year or so even if protected from predation and disease. Oxygen kills just as nuclear radiation does, by destroying the instructions within our cells about reproduction and repair. Oxygen is thus a mutagen and a carcinogen, and breathing it sets the limit of our life span. But oxygen also opened to life a vast range of opportunities that were denied to the lowly anoxic world. To mention just one of these: free molecular oxygen is needed for the biosynthesis of those special structure-building amino-acids, hydroxylysine and hydroxyproline. From these are made the structural components that made possible the trees and animals.

Paul Crutzen, an atmospheric chemist, was the first to draw our attention to the far-reaching geophysiological consequences of a major nuclear war, the "nuclear winter". We need to be reminded, often, just how bad that ultimate sanction can be so that it remains a deterrent. But, like oxygen, nuclear energy provides opportunities and challenges us to learn to live with it.

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