« PreviousContinue »
betatron, or the various forms of linear accelerater which are appearing in increasing numbers. These are electromagnetic devices in which particles are accelerated in a succession of boosts to very high energy and radiation is achieved analogous to those which may be obtained from radium and other elements at will.
Most of the cancer research dealing with therapy supported by the Atomic Energy Commission is carried on in research hospitals, each placing special emphasis upon one of the modes of producing effective radiation. Four such major centers or hospitals are in existence. There is one each at Brookhaven, Oak Ridge, Chicago, and San Francisco, in the radiology laboratory of the University of California Medical School at San Francisco.
At Brookhaven the research emphasizes the use of neutrons from the reactor there. The Oak Ridge Cancer Hospital is the chief center for the utilization of isotopes, either internally or externally in powerful radiation sources; the new Argonne Cancer Research Hospital at Chicago enjoys access not only to reactors but to acceleraters in several different forms, while the radiological laboratory at San Francisco is exploring the utility of the 70 million electron volt synchrotron. Each of these hospitals, I think it is important to realize, is affiliated with the regional medical schools and works closely with the medical schools.
The number may vary from 9 universities affiliated with the Brookhaven laboratory to about 27 affiliated with the Oak Ridge group.
To lay before you in a more comprehensive manner the programs of these various centers we have requested that representatives join us here in order that they may explain directly to you the nature of the operations and the nature of the research they are carrying on.
Dr. Robert Stone, who directs the program at San Francisco, which I mentioned, cannot be with us, and for a discussion of the progress of this research center, as well as the broad outline of the activities of the medical branch, I wish now to turn the discussion to Dr. Dunham, on my left, who is the Chief of the Medical Branch, and will also speak for the San Francisco program.
The CHAIRMAN. Before we start the hearing of Dr. Dunham's statement, I was aware, as I am sure every layman in this audience is, of the use of very technical terms and names that certainly I have never been acquainted with in any of my activities, and I assume that it would be rather difficult for the reporter to get down those names as accurately as we would like, and as we would wish to have in the record. I also am of the opinion that the reporters of our newspapers who are present would likewise have some difficulty in doing it.
I noticed while you were giving your statement that you referred occasionally to notes or some prepared statement that you had before you. If there is any additional copy of that, I would be pleased if the reporter could have it so as to make certain that he has it just as you wish it to be in the record. If there are additional copies, I would be glad to have the use of one of them for the benefit of the newspaper reporters who are present, to select any material from that they might feel would be important to make reference to.
Do you have any extra copies?
Dr. BUGHER. At the moment I do not have an extra copy here but we will produce them.
The CHAIRMAN. I will tell you what I would suggest if you will let us have that copy for use by our reporter and in the meantime make it available to our newspaper friends who are present so that they could select from it any part they might wish, assuming that there are parts they would make reference to, then I will have copies of that made for them by our stenographic staff so as to be of some assistance to
you, and I leave that entirely to them. If you will deliver what copies you do have, it will be helpful to us.
Mr. CARLYLE. Mr. Roberts has just informed me that the reporter happens to be from Alabama and he would not need this extra information.
The CHAIRMAN. I am just informed by Mr. Roberts, a member of this committee from Alabama, that the reporter who is taking down this testimony comes from Alabama, and that being the case he would need no extra help other than the oral presentation.
Of course we are all familiar with the brilliance of these folks that come to us from Alabama, including our colleague on this committee, and if he had made me aware of that fact, maybe I would not have had to extend this solicitude to the reporter.
I think that Mr. Dolliver would like to ask a question, if he may.
Mr. DOLLIVER. As I understood your testimony, the atomic radiations are not only a cause, but also a cure for cancer.
Dr. BUGHER. You are quite right. The effects of radiation are within the cell, and the effects may be profound so that a cell which has been subjected to radiation and not killed may be made abnormal in various ways, particularly where there has been continuous radiation.
Particularly where there has been continuous radiation over a long period of time, the cell may not be killed but may be made so abnormal that it becomes incapable of sustained growth, which is really cancer. So, we think particularly in this respect of radiation applied to sensitive tissue over a long period of time as an example of the sort of thing that we have in mind. We cite the cases of radium poisoning where radium is deposited in the bone and continues to give off its various radiations, and in the course of years the bone may develop a tumor which may destroy the individual. The time lags may be on the order of 10 or 15 years from the time the radium is first taken into the body until a difficulty such as this appears.
That is an example of the one type of thing by the same energy that can partly injure a cell and then also if applied in sufficient intensity kill it. The objective of tumor therapy is to kill the cancer by one way or another. Consequently radiation may also be used as a means of destroying the cancer and that usually involves application of radiation at high intensity for a short period of time, whereas the cancerproducing tendency is manifested only over a long period of time.
Mr. DOLLIVER. The resulting thought that comes to me is that whether you give cancer or whether you cure it, depends upon the intensity of the application of these radioactive materials?
Dr. BUGHER. Yes; that is correct. In the case of radium there are some levels of poisoning below which we have not seen any cases of cancer resulting. In general, the more of the material which the individual has in his body, the greater the risk, and we attempt to determine a level below which the risk appears to be negligible and take
that level as a permissible limit. We all have small amounts of radium in our bodies as a part of our natural environment, but ordinarily that gives no difficulty.
Mr. DOLLIVER. I am greatly puzzled as to the relationship between X-rays and the X-rays that are gotten from a cyclotron or any one of those high-voltage machines; that is, the relationship between the rays that come out of radium which we have known for a generation or more and the rays that come from the various elements you have mentioned-new elements such as plutonium and others that have been discovered by atomic-energy research.
Is there any elaboration of those relationships which would be understandable by laymen?
Dr. BUGHER. No, sir; I am sure it is not beyond the scope of understanding. It is rational but not altogether simple.
If I may explain here—the forms of radiation which may be given off by a radioactive element may differ considerably. Now, one of them, for instance, is the gamma radiation which, as I mentioned, is similar to X-ray that is transmitted in the same manner that light is transmitted with the same speed, and the only difference beween gamma radiation and our ordinary X-ray is that gamma radiation is produced by an atomic nucleus, whereas X-ray is produced by bombardment of a target in a special tube. Usually the gamma radiation is a relatively high energy, where the ordinary X-ray is comparatively low, but that distinction does not always hold true.
Then, in addition to that type of radiation which is transmitted with the speed of light and behaves in many ways as does light, then we have particular forms of energy that are shot off from the nucleus. Some of those are very large and some are very small. The large one which I mentioned as the alpha particle is actually a core or the nucleus of the helium atom.
Mr. DOLLIVER. Now, when you say “large” you mean large enough to be seen under a microscope?
Dr. BUGHER. No.
Dr. BUGHER. We are talking about entirely submicroscopic and atomic things. The dimensions are then very minute fractions of millionths of an inch. The alpha particle is really itself an atomic nucleus. The beta particle, which I mentioned, is very, very much smaller, and is an electron which is traveling at high velocity. It is a small, extremely minute charge on a very minute particle of mat
almost weightless, if we want to put it that way. Then the neutron, which I mentioned, is one of the constituents of the atomic nucleus that does not have any charge. It is very difficult ordinarily to detect. But none the less it is readily absorbed by other atomic nuclei with the production of new elements, actually. All of these radiations differ enormously in their
gamma radiation may be projected actually for a mile or more. The neutron may itself, depending on its energy, travel considerable distances and penetrate surprisingly dense material.
As an example of that, at Nevada when we wish to do a neutron experiment, protecting the experimental material from the heat and all of that, we put these experimental devices, materials, and animals inside of lead chambers thick enough to stop the gamma radiation, but the neutrons will come through as much as 7 inches of lead without
being very much reduced. So that there is marked difference in range.
Mr. DOLLIVER. Right at that point, by the word “neutron” do you mean it is neutral, has no effect?
Dr. BUGHER. Has no charge; that is right.
Mr. DOLLIVER. Has none of the effects attributable to gamma and alpha and beta rays?
Dr. BUGHER. All of these radiations have certain things in common. They all produce ionization. That is to say, they cause disintegration of the molecules of tissue and of water with the production of charged molecules, so we call them ionizing radiations.
Although the physical properties of the radiations differ very markedly, their biological results are essentially similar, so we tend to group them all together here.
Mr. DOLLIVER. I am afraid I interrupted your train of thought there, Doctor.
Dr. BUGHER. No, sir; that was a very helpful question.
Mr. DOLLIVER. Now, to go a little further afield than that, we are all of us familiar with certain natural oscillations and waves. The sound waves, we know, for example, are oscillations of "circumambient air” as Mr. Shakespeare once said. We know about the radiation of light which we enjoy with sight. Then there are what we call radio radiations and in the radio range there are many variations of speed and wavelength.
Is there among scientists a grouping of all these various radiations that are natural phenomena, or do they separate them out into their various fields and consider them totally unrelated?
Dr. BUGHER. In ordinary discussions I think one tends to speak of them as though they were unrelated, but in fact one can regard electromagnetic radiations such as light and radio waves as a continuous system or a continuous gradation of change of wavelength from the very long radio waves, which may be measured in hundreds of yards in wavelength, through visible light, which is only a very small portion of this spectrum where the dimensions of the waves are minute fractions of a millimeter, measured in millionths of a millimeter, actually, all through the ultravioet range which is not visible but stíll shorter in wavelength, to the X-ray, which is still shorter, and finally to these high-energy gamma radiations where the wavelength is very short, indeed.
Mr. DOLLIVER. There is a progression, then, from the visible light and below the visible light in the infrared rays on clear up to the radiation received from radioactive materials?
Dr. BUGHER. Yes, sir; that is true.
Dr. BUGHER. Radium gives off three different kinds of radiation from the same atom. The gamma radiation comes off, which I mentioned. From time to time the radium atom extrudes, shoots off, alpha particles, which are the heavy helium nuclei of which I spoke. And also from time to time the atom emits beta particles. So that from the spontaneous radioactivity of radium three different types of radiation result.
Mr. DOLLIVER. But they are in the spectrum you referred to?
Mr. DOLLIVER. Now you said something about the care or solicitude which your division of the Atomic Energy Commission, the Division of Biology and Medicine, has with respect to the handling of atomic materials from the very time it is mined until it is finally disposed of. There are mineral resources from which fissionable materials are obtained, which are scattered over the earth pretty generally; is that right! Dr. BUGHER. Yes, sir.
Mr. DOLLIVER. Does that material in its natural state have the same results with respect to the production of cancerous tissue, as it would in the refined state!
Dr. BUGHER. We are speaking really of uranium.
Dr. BUGHER. The natural occurring uranium is radioactive partly due to the fact that it breaks down within itself to radium, so that the natural uranium therefore always carries a certain degree of radioactivity, which is very low. Naturally, if one concentrates the radium the material is more active than it was in the beginning, but pure uranium is not in itself very markedly radioactive. There is a spontaneous activity there, but most of the activity of natural uranium comes from the contained radium.
Mr. DOLLIVER. In other words, in its natural state it does not present a health hazard to any appreciable degree?
Dr. BUGHER. I think we do feel that it must be regarded to have a health hazard from two aspects. One is the contained radium which I mentioned; and the other is that uranium is itself a chemically toxic material entirely apart from the question of radiation. So that we do not like to see people acquiring any appreciable amount of uranium, even though the danger from radiation itself would not be very great. But the material is chemically toxic.
Mr. DOLLIVER. You mentioned the fact, too, that some of these materials, and I think you mentioned plutonium, did not occur naturally on the earth. Has science been able to determine whether it exists anywhere in the universe; that is, in the solar system or otherwise ?
Dr. BUGHER. So far as I know I do not believe that the spectroscopic study of stars has disclosed any of these transuranic elements, the ones that are beyond our level of uranium. It may be that some of my associates would have more specific information on that, but I have never seen any note of the recognition of these elements in the stars.
Mr. DOLLIVER. What brought that question to my mind was the fact that helium was first discovered on the sun before it was found on the earth. Is that correct?
Dr. BUGHER. Yes. These special elements are all unstable, so that they tend to disintegrate spontaneously over a period of many years.
Mr. DOLLIVER. There may have been a time when they did exist for short periods, short intervals, and were transmuted into other forms, just as is done in your operations in refining uranium?
Dr. BUGHER. Yes, I should think so.