CHAPTER XII. Danger to the Individual

Danger to the Individual

How much harm is being done by the atomic tests? Some scientists have claimed that from past tests alone about 50,000 persons throughout the world will die prematurely. There is no general agreement on this point. Some think the number should be smaller. It is possible that radioactivity produces some effects which prolong life rather than shorten it. But even if all the biological consequences of radiation were known many questions would still demand answers. Can tests be justified if they actually shorten some human lives? Even the possibility of a health hazard must be taken most seriously. On the other hand: Are there any reasons which make continued testing necessary?

We shall return to these questions in a later chapter. First, however, we shall try to put before the reader the known facts about the fallout danger to the individual. We shall try to put this danger into perspective by relating it to other more familiar dangers to which all of us are exposed. In the following chapter we shall discuss how the fallout may affect future generations.

The dangers from big doses of radiation are well known. Exposure to a thousand roentgens over our whole body causes almost certain death in less than thirty days. Four or five hundred roentgens give a fifty-fifty chance of survival. At less than a hundred roentgens, there is no danger of immediate death. Three years ago the Marshallese got a dose of 175 roentgens. None died. Apparently all are in good health.

Over longer periods of time even bigger radiation doses can be tolerated. A thousand roentgens spread over a lifetime produce no apparent biological consequences in individual cases. A rough rule (which is not too well-established) is that five times as much radiation can be tolerated if one is exposed to only a little radiation at any one time.

A hundred roentgens all at once, or several times this amount over a protracted time period, will not cause sickness or death that can be directly blamed on the radiation. However, such a dose of radiation may have harmful biological consequences which are more subtle. An exposed individual may develop an increased susceptibility to certain diseases, notably bone cancer and leukemia. Leukemia is a fatal disease in which the white blood cells multiply too rapidly.

A person who receives a hundred roentgens does not necessarily contract bone cancer or leukemia. Rather, his chance of contracting these diseases during his lifetime may have been increased. Knowledge of this kind can be obtained only with the help of statistics.

If, for example, a large number of mice receive a heavy dosage of radiation over a long period of time, one finds that the incidence of tumors and leukemia is higher amongst such irradiated animals than the natural incidence of these diseases.

Direct evidence with human beings—fortunately—is rather scarce. Statistics exist on the survivors of Hiroshima and Nagasaki, and also on radiologists. The latter group probably receive several hundred roentgens during their professional lifetimes. In addition, some statistics exist on children who have been treated with large doses of radiation for enlarged thymuses. Persons suffering from ankylosing spondylitis, which is a painful disease of the spinal joints, have also been treated with large X-ray doses. The statistics in all these cases lead to the same conclusion: that large doses of radiation increase the likelihood that an individual’s life will be shortened by leukemia and possibly also other cancers. Furthermore, it appears (mainly from the experiments on animals) that the increased likelihood is simply proportional to the amount of radiation received, at least for doses in the neighborhood of several hundred roentgens or so.

This of course sounds frightening. But the radiation doses from the world-wide fallout are in a completely different class from those we have been discussing. They are very much smaller. On the average human bones are getting about 0.002 roentgens per year from the Sr⁹⁰ in the fallout. In addition the whole body is receiving a roughly equal amount in gamma rays, mainly from Cs¹³⁷. These figures apply to new bone in young children who have grown up in an environment of Sr⁹⁰ in the northern part of the United States. This is a region of maximum fallout. Adults whose bones were made for the most part before the atomic testing started are getting about 0.0003 roentgens per year from Sr⁹⁰. None of these figures appears to be alarming.

At this present rate a lifetime dosage in northern U.S. is only a small fraction of a roentgen. A rare individual might get several times this amount. If tests continue at the present rate, radiation levels could increase by as much as five-fold. However, even in this situation it is difficult to imagine anyone receiving a lifetime dose of more than five or ten roentgens from the world-wide fallout. A more reasonable estimate for the average lifetime dose would be a few roentgens or less.

One might conclude from these figures that there is no danger whatsoever from the fallout. This conclusion, however, may not be correct.

The danger from such small doses of radiation is not easy to define. Even the best statistical methods are insufficient. One is looking for small effects which show up only after millions of cases have been studied. Animal experiments are extremely difficult to carry out under these conditions. Direct controlled experience with human beings is, of course, impossible. As a result, one is forced to draw conclusions from the effects at higher dose levels, where experimental data have been obtained.

This may be done in many ways. One way is to assume that the law of proportionality holds down to the smallest doses. This means that one roentgen produces one hundredth as many cases of bone cancer and leukemia as 100 roentgens produce. This law is plausible. It is by no means proven.

By arguing in this way one finds that for each megaton of fission energy which escapes from the test site in the world-wide fallout the lives of approximately four hundred persons would be shortened by leukemia or bone cancer. Under present conditions of testing, roughly one half of the fission products are deposited as close-in fallout in and near the test site. Per megaton of fission energy exploded, therefore, perhaps 200 persons may get leukemia or bone cancer. This figure could actually be higher, possibly even a thousand persons or more per megaton. It could also be lower. It could be zero.

It is possible that radiation of less than a certain intensity does not cause bone cancer or leukemia at all. In the past small doses of radiation have often been regarded as beneficial. This was not supported by any scientific evidence. Today many well-informed people believe that radiation is harmful even in the smallest amounts. This statement has been repeated in an authoritative manner. Actually there can be little doubt that radiation hurts the individual cell. But a living being is a most complex thing. Damage to a small fraction of the cells might be beneficial to the whole organism. Some experiments on mice seem to show that exposure to a little radiation increases the life expectancy of the animals. Scientific truth is firm—when it is complete. The evidence of what a little radiation will do to a complex animal like a human being is in an early and uncertain state.

In any event the number of additional cases of leukemia and bone cancer due to the fallout radiation is certainly too small to be noticed against the natural incidence of these disorders.

In the next thirty years about 6,000,000 people throughout the world will die from leukemia and bone cancer. From past tests, which have involved the explosion of about fifty megatons of fission energy, the possibility exists that another 50 × 200, i.e., 10,000 cases may occur. Statistical methods are not able to find the difference between 6,000,000 and 6,010,000. There is no way to differentiate between the fallout-induced cases of leukemia and bone cancer, and those which occur naturally.

The possible shortening of ten thousand lives may seem rather ominous. But mere figures can be misleading. A better way to appreciate the danger from fallout is to compare it with other more familiar dangers. Such a comparison can be made with the natural background of cosmic rays and radioactivity in the earth and in our own bodies.

We are constantly and inescapably exposed to this radiation. Our ancestors have been exposed to it. The human race has evolved in such a radioactive environment. Moreover, the biological effects from different kinds of radiation can be compared in a meaningful way in terms of roentgens. Therefore the danger from Sr⁹⁰ is not unknown in every respect. In some ways it is very well-known because we and all living beings have spent our days in a similarly dangerous surrounding. We live on an earth which has radioactivity in its rocks, which carries a similar activity in its waters, and which is exposed from all sides, to a rain of particles which produce effects identical with the effects of radioactive materials.

Not all radiations which have the same intensity (the same number of roentgens) have precisely the same effect. The damage produced also depends somewhat on the spacing of the ionized and disrupted molecules. The cosmic rays and the Sr⁹⁰, however, are quite similar even in this respect.

The reader will recall that the spacing of the ionization depends only on the charge and the speed of the ionizing particle. The ionizing particle from the Sr⁹⁰ is an energetic beta ray, which has a charge of one and a speed close to that of light. A large part of the background radiation which reaches our bones comes from the cosmic rays. The main portion of the cosmic rays is due to the mesons. The meson, like the beta ray, has a unit charge and a speed close to that of light. The two particles may therefore be expected to produce identical biological effects. The only difference between their effects is that the beta ray does not have enough energy to leave the bones, while the meson is so energetic that it deposits its energy both in our bones and throughout our whole body. Thus if we compare a Sr⁹⁰ dose with the same dose of cosmic rays the same effect to the bones must be expected. But the cosmic rays give rise to additional effects in our bodies.

The total background dose to the bones is about 0.15 roentgens per year for the average person living at sea level in the United States. Of this amount, about 0.035 roentgens is due to cosmic rays. At higher altitudes the cosmic ray dosage increases. In Denver, at an altitude of 5000 feet, the cosmic rays contribute 0.05 roentgens per year.

The above numbers should be compared with the present level of world-wide fallout radiation to the bones: about 0.003 roentgens per year (from Sr⁹⁰ and other sources). The fallout radiation is thus only a few per cent of the natural cosmic radiation. It is small even when compared to the variation of cosmic ray intensity between sea level and 5000 feet.

A correlation between the frequency of leukemia and bone cancer, and the intensity of natural radiation has been looked for. Some statistics for the year 1947, before weapons testing began, are available. They show the number of cases of these diseases occurring in that year per 100,000 population.

Bone Cancer Leukemia

Denver 2.4 6.4 New Orleans 2.8 6.9 San Francisco 2.9 10.3

The extra radiation that one gets in Denver from cosmic rays is many times greater than the fallout radiation. But the table shows no increased incidence of bone cancer or leukemia. On the contrary—the incidence of these diseases is actually lower in Denver.

Not all of the natural background radiation is due to cosmic rays. Part of the background comes from natural radioactive elements in the soil and in the drinking water. These include uranium, potassium⁴⁰, thorium and radium. Radium behaves like calcium and strontium, and gets deposited in our bones. All these effects are, to the best of our knowledge, at least as intensive in the Denver area as in San Francisco or New Orleans.

One possible explanation for the lower incidence of bone cancer and leukemia in Denver is that disruptive processes like radiation are not necessarily harmful in small enough doses. Cell deterioration and regrowth go on all the time in living creatures. A slight acceleration of these processes could conceivably be beneficial to the organism. One should not forget that while radiation can cause cancer, it has been used in massive doses to retard and sometimes even to cure cancer. The reason is that some cancer cells are more strongly damaged by radiation than the normal cells.

In spite of the table, however, there may actually be an increased tendency toward bone cancer and leukemia that results from living in Denver. If so—and this is the main point—the effect is too small to be noticed compared to other effects. We must remember that Denver differs from New Orleans and San Francisco in many ways (besides altitude), and these differences may also influence the statistics.

A more thorough consideration of the background radiation gives further evidence that this radiation is more important than the present or expected effects of Sr⁹⁰. The radium deposited in our bones from drinking water has been observed to reach values as high as 0.55 roentgens per year. Furthermore the heavier and slower alpha particles emitted by radium cause ionization processes which occur in closer spacing and are therefore more damaging than the ionization due to Sr⁹⁰. To make things worse radium is deposited in our bones in little nodules (hot spots). Thus the possibility of local damage is enhanced.

The background radiation to which we are exposed varies for some unexpected reasons. It has been pointed out recently that brick may contain more natural radioactivity than wood. The difference between living in a brick house and living in a wood house could give rise to ten times as much radiation as we are currently getting from fallout. (The additional radiation from the brick might be as much as 0.03 roentgens per year.)

Human beings are subject to radiation not only from natural sources, but also from man-made sources. One of these is wearing a wrist watch with a luminous dial. Another is having X-rays for medical purposes. Both of these sources give much more radiation than the fallout.

Of all ionizing radiation to which we are exposed the X-rays are most important. In some cases medical X-rays have intensities which are noticeably harmful. Yet this damage is practically always of little consequence compared to the advantage from correct recognition of any trouble that the X-ray discloses.

We may summarize in this way. Our knowledge of the effects from the fallout is deficient. We cannot say exactly how many lives may be impaired or shortened. On the other hand, our knowledge is sufficient to state that the fallout effect is below the statistically observable limit. It is also considerably less than the effect produced by moving from sea level to an elevated location like Denver, where cosmic radiation has a greater intensity. It is also less than having a chest X-ray every year. In other words, we know enough to state positively that the danger from the world-wide fallout is less than many other radiation effects which have not worried people and do not worry them now.

We have compared radiation from the fallout with radiation from other sources. It is also possible and helpful to compare the fallout danger with different kinds of dangers. For this purpose it is convenient to express all dangers in terms of a reduced life-expectancy. For example, smoking one pack of cigarettes a day seems to cut one’s life-expectancy by about 9 years. This is equivalent to 15 minutes per cigarette. That cigarettes are this harmful is, of course, not known with certainty. It is a “best guess,” due to Dr. Hardin Jones, based on an analysis of statistical data. A number of Dr. Jones’ statistical findings are listed in the following table:

Reduced Life Expectancy

Being 10 per cent overweight 1.5 years Smoking one pack of cigarettes a day 9 years Living in the city instead of the country 5 years Remaining unmarried 5 years Having a sedentary job instead of one involving exercise 5 years Being of the male sex 3 years Automobile accidents 1 year One roentgen of radiation 5 to 10 days The world-wide fallout (lifetime dose at present level) 1 to 2 days

The reader will see that the world-wide fallout is as dangerous as being an ounce overweight or smoking one cigarette every two months.

The objection may be raised that the fallout, while not yet dangerous, may become so as more nations develop and test atomic weapons. On this point we can only say that the future is not easy to predict. Some factors, however, justify optimism. We are learning how to regulate the fallout by exploding bombs under proper surroundings. Development of clean bombs will greatly reduce the radioactivity produced. Deep underground tests will eliminate fallout altogether. The activity put into the atmosphere in 1954 was considerably greater than the activity released in any other year. It is highly probable that the activity produced by United States tests will continue to decline.

Finally, we may remark that radiation is unspecific in its effects. Chemicals are specific. About the effects of a new ingredient in our diet, in our medicine, or in the air we breathe, we know much less than we know about radiation. If we should worry about our ignorance concerning our chemical surroundings as we worry about the possible effects of radiation, we would be condemned to a conservatism that would stop all change and stifle all progress. Such conservatism would be more immobile than the empire of the Pharaohs.

It has been claimed that it is wrong to endanger any human life. Is it not more realistic and in fact more in keeping with the ideals of humanitarianism to strive toward a better life for all mankind?