ence, which try to be scientific at least, a poor calculation until we have better data.

Representative PRICE. Then you stated that most diligently executed research is needed to resolve this. Did you mean to leave the impression that we are not doing anything in the way of a research effort in this regard, or that it is not as extensive as it should be?

Mr. PARKER. I meant, sir, that I hope the medium of these very important hearings would help to clarify for those doing this research what the key problems now seem to be upon this joint review and to work diligently on these key problems, perhaps recognizing some that were more evident or soluble. Perhaps agreeing that with any prescribed length of time, such as 10 or 20 years, certain problems by their nature are not completely soluble. This is what I meant to cover in that point.

Representative PRICE. What is the difference between levels of acceptability of radiation exposure and performance standards?

Mr. PARKER. I would not understand how you would characterize the performance standard, Mr. Price.

Representative PRICE. This is the casual reference sometimes to the performance standard and the level of acceptability. The performance standard is what you would take on in the performance of the work. The reason I ask the question is because it refers sometimes to the level of acceptability and sometimes to the performance standard. Mr. PARKER I see. Neither of these are terms that I would find used in the particular areas of radiation protection with which I am more familiar.

Representative PRICE. I have seen it used.

Mr. PARKER. In our case performance standards would be a measure of how well we had found we had in practice achieved the reduction of limits or limitations of exposure that we had thought proper to prescribe.

Representative PRICE. Would there be any difference between that and the level of acceptability of radiation exposure?

Mr. PARKER. The level of acceptability could to some people-and I am sorry I am not familiar how it was used in the particular reference that you have in mind, sir-mean in advance a level of acceptability in different cases. For example, we all think it imprudent to offer the same amount of radiation exposure to children and possibly old and infirm people as compared to a mature adult population. There is a concept of a level of acceptability involved there. This is what I would call a level of acceptability. The performance would be the measure of how well this was achieved by the responsible people. I do not know, sir, whether it was meant in this sense in the reference that you have. I would be very happy to look this up outside of the meeting and report to your committee.

Representative HOLIFIELD. The level of acceptability in the case of an individual might vary considerably, as you pointed out, between an elderly person and a child. It also might be higher where you were using X-ray for cancer treatment or something like that. An individual might accept quite a considerable dose in a local area which would not be acceptable ordinarily to populations; isn't that true?

Mr. PARKER. It is indeed so, Mr. Holifield.

RADIATION PROTECTION

Representative PRICE. You brought that out in your own statement.
Mr. PARKER. Excuse me, sir. I didn't hear the question.

Representative PRICE. You brought that out in your statement this morning as to the level of acceptability.

Mr. PARKER. Yes, in other terms.

Representative PRICE. That is all I have, Mr. Chairman.
Representative HOLIFIELD. Mr. Hosmer.

Representative HOSMER. In discussing the threshold theory and discarding it in your hypothesis, at least, you made the assumption that it is generally conceded that radiation of any amount causes changes that are deleterious. Yet we find man evolving what we think is upward in quality as an animal in a background environment of radiation. How do we reconcile that?

Mr. PARKER. Mr. Hosmer, let me attempt to answer that question in two parts, or perhaps more honestly to answer the first part and duck the second part. The answer to the first part is that one has not said whether one is discarding the threshold effect. Merely one says that the evidence is incomplete, and this is the key technical problem that has to be resolved.

In the absence of its resolution you select the approach to the problem that will seem to be the most conservative, which is to accept the no-threshold effect. This implies to some degree additivity of deleterious genetic effects through all the generations, as you mentioned. Why I divided the question into two parts is because I do wish to duck the firm response to the second part on the grounds that I have made some point of the great mistake that many of us make in stepping well outside of our bounds of professional qualification. The question you ask, I believe, sir, is one in which the geneticists have a useful contribution to make, and which I as a layman from the genetics point of view have tried hard to understand in full. would make no real contribution by making a definitive statement and so using the opinion of the geneticists at secondhand. I do recommend that the point be addressed to a suitably qualified witness. later, sir.

I

Representative HOSMER. In that connection, I think one of the points that was made in the paper by Harris 2 is the fact that these standards should not be established by physicists or any particular discipline alone, since they involve matters of economics, sociology, and things of that nature, they necessarily should be established on the basis of a diversified committee coming to some general agreement. Is that essentially what our problem is?

Mr. PARKER. This is essentially built into the language that I have tried to use this morning as to value judgments.

Representative HOSMER. You mentioned the importance of public understanding in obtaining the acceptance of whatever standards: might eventually be evolved. How do we overcome the very difficult problem of terminology? In the preprint we have set forth a special table of terms. You have used several different expressions in your testimony that I think only the real experts can grasp at first hearing sufficiently to bring to mind the concept of their meaning.

2 See Selected Materials, pp. 49 and 50.

What I am essentially getting at is that, although the general public doesn't know what a watt is of electricity, they have an understanding whether they want a 50-watt or 70-watt or 100-watt light bulb. They go down and buy one. Is there any key of that nature that can be developed so that public understanding of radiation can be facilitated? Mr. PARKER. This is again not an easy question to answer. Let me say first that by the time we have had our present battery of radiation units in practical use as long as the term "watt" has been in use, I believe its degree of familiarity to the public will be about. equal. At the present time it is not so large. There is a complex battery of radiation units which was in fact only developed and used in a small coterie of atomic energy projects, beginning in about 1943. These were promulgated, beginning about 1946 or 1947, to a wider audience, and have gone through the process of what you might call clinical trial and error which have caused them to be modified. So we have arrived by more or less agreement of the scientific fraternity at two units in current use which have some continuing substance, although a limited substance.

Of these two, the physical one, which is known as the rad, is a measure of expression which I believe can be with confidence promulgated to all and its meaning known through standard forms of teaching.

The unit rem has a different character in the sense that it is not as significant a unit in the absence of the arbitrary scale of relation that I mentioned that defines applicable radiobiological effectiveness values for all of the particular cases. This multiplies the task of teaching to the public the true meaning of such a unit.

One should not put some numbers on this because it has no numbers. It is an order of magnitude more difficult to convey this meaning to a large audience and not have the next speaker inadvertently convey quite a different meaning.

Representative HOSMER. As a matter of fact, in the instructions you received as a witness you were told to deliver your testimony in terms understandable by the layman. You have found it impossible to comply with that instruction, have you not?

Mr. PARKER. This is what you are saying. This means that we have failed in an attempt to reduce the language to generally understandable terms without further elaboration.

Representative HOSMER. The reason I pursue this line of inquiry is merely to emphasize that, along with all the other problems that may be mentioned during these hearings, communications and terminology are important ones to solve in order to achieve what we seek-acceptable standards in this whole area.

Just for the purposes of the record, I think you have indicated that the average person obtains about three rem of irradiation from diagnostic X-rays during his lifetime. What contribution does one chest X-ray make to that?

Mr. PARKER. The number that is conventionally written down for a chest X-ray depends on whether we are talking about the fluoroscope process or look-see process or the actual radiographic process or taking the photograph. The look-see or fluoroscopic process is normally charged between 1 and 2 roentgens as a representative value for

the chest. You must recall again, sir, that the actual radiation dose will vary at all points on the chest in this procedure.

Taken as a radiographic photographic process, the necessary dose is generally taken as about one-tenth of that in the look-see method, or one-tenth to two-tenths of a roentgen.

Representative HOSMER. In other words, the fluoroscopic procedure gives a relatively high dosage.

Mr. PARKER. Very much higher than the photographic process. Its justification is that only by a fluoroscopic or direct look-see process or some indirect sort of moving sequencing can you get the sense of motion which is needed for the clinical examination in some cases. It does not say that fluoroscopy should be used where radiography satisfies the inquiry of the physician.

Representative HOSMER. I think you indicated it has between 100 and 200 for a photograph.

Mr. PARKER. I think those are generally taken as representative. Representative HOSMER. Thank you.

(The following supplementary information was submitted for the record by Mr. Parker:)

On Tuesday, May 24, I endeavored to answer a question from Representative Hosmer on the amount of radiation received during chest radiography. As I recall, I quoted a dose of about 1 roentgen for the indirect fluoroscopic method and a dose of about 100 to 200 milliroentgens for direct radiography. These numbers are appropriate for the average dose received by the chest region in such practices. However, it is now clear that the intent of Mr. Hosmer's question was to determine representative dose to the reproductive organs. Such doses are broadly in the range of 0.1 to 0.5 percent of the numbers quoted. There is a wide variation in the actual dose to the reproductive organs during these procedures. The range of reported values that I find is from 0.01 to 3 milliroentgens. It may be noted that Dr. Chamberlain on Wednesday, June 1, quoted numbers which range from 0.1 to 0.5 milliroentgens using modern techniques. There is no particular discrepancy between our figures, since mine include, at one extreme, very low values obtained with special methods not yet considered to be general modern practice and, at the other extreme, the high values connected with the fluoroscopic method.

Representative BATES. I want to touch on the same point that Mr. Hosmer made relative to an informed public. After listening to your statement, realizing the magnitude and complexity of the problem, we come to the point where you indicate the public should be informed. This appears rather difficult and particularly after I read part of your statement where you say taking points 4, 5, 6, and 7 together, man gets so subdivided between space and time and radiation types and radionuclides that the base integrating sense of standards is lost. Those are the words of an expert in the field. I wonder how we can at this time inform the public? You indicate that this authority of knowledge should be accepted, I presume, by faith. People who are experienced in the field are working on it. People cannot measure in their own minds the terms that we use, rems and rads. They can understand a foot or a pound or something like that. Particularly when the experience of damage in the field has been so limited. People have been burned by fire, and they can understand the dangers there. They drown in water, and they can understand that. What can you say in a brief statement that would at this time inform the public in addition to the fact that they should have faith in the people who are working in the program?

Mr. PARKER. These are some of the most significant points in the whole affair, Mr. Bates. Let me say this, that one is faced with this enormous mass of preprint material and in a first review of it, one perhaps emphasizes the difference in contempt and presentation of the intended witnesses. But if one steps back a pace and takes a more objective view, I believe it is proper to say that there is a remarkable degree of uniformity on the keypoints throughout this preprint material, and thus, I believe, throughout the material that will be presented. If these 2 weeks of hearings emphasize the point that although some of us tend to quibble on the third decimal place of some expression of limits, on certain key points there is almost unanimous agreement among those perhaps qualified to have competent. opinion. This, I believe, is what will tend to establish in the public this feeling of support of knowledge of those who are currently working in this field. I would consider it, in detail, hopeless to inform the public on all the ramifications of all the handbooks put out by responsible bodies in this field. But I do think that certain basic principles can be shown here to be agreed upon by those qualified, and that this provides the basic assurance to the public that very probably the fine points are under much better control than they occasionally see when one tends to rather emphasize the difference in expression rather than the basic similarity.

Representative BATES. As you know, there is a good deal of fear in the minds of many people concerning the possible effects of radiation. That has been expressed in many forms, whether it is ocean disposal in my area, or other places throughout the country. You indicate that faith in people is one thing. But it is difficult for people to accept something merely on faith, especially when they don't understand it, and as you indicate, the details are so far reaching that they could not possibly understand it anyway.

Mr. PARKER. There are some points in this area which I am sure will be clarified in these 2 weeks, some which I rather consciously left out of what was intended as a summary. One point is the fear in the minds of many that if one goes slightly beyond some written limit, some dire consequence will occur. We establish a limit perhaps in some cases of 5 rem per year. I am sure there is a feeling in some areas that if any individual has been exposed to 6 rem his life is ruined. I believe that the responsible witnesses will show the fallacy of any such line of reasoning during this period. This may make a real contribution.

Representative BATES. Of course, the uncertainties of any new field make people much more suspect and much more reluctant to accept something new than something that they have lived with for a long time. For instance, automobile accidents, 45,000 deaths a year. If that was part of this program we would have to close up the shop right away. People would never accept that.

Mr. PARKER. The program is bedeviled by its own past excellence compared with other protection programs plus the demand for many other investigations needed. This is what I referred to as the second implied need for balance in our national structure, a perspective in respect to hazards of all kinds.

Representative BATES. All of this will be developed as the hearings proceed?

Mr. PARKER. I hope to hear it so developed, sir.