and what we do in low probability events of a high potential consequence, we will have to go back and revise everything that everybody said today. We intentionally restricted our earlier remarks to normal operation, routine things that happened with low level radiation.

I think we ought to stick to the subject.

1/ Bureau of Radiological Heath. Food and Drug Administration. Population Exposures to X-Rays: United States, 1970. Washington, D.C. Govt. Print. Off. Nov. 1973. (FDA-73-8047).

2/ Modan, B. et al.

Radiation-Induced Head and Neck Tumours.

Lancet. v. 50. n. 7852. Feb.1974: 277-279.

3/ Lassiter. Laboratory Management Participation in Long Term Investigation of Man in Occupational Monitoring for Genetic Hazards Workshop. Annals of the New York Academy of Sciences. v. 269. March 1975: 43-45.

4/ Hunt, V.R. Occupational Health Problems of Pregnant Women. A Report and Recommendations for the Office of the Secretary of the Department of Health, Education and Welfare. Washington, D.C. Govt. Print. Off. April 30, 1975. (FA-5304-75).

5/ Bureau of Radiological Health. Food and Drug Administration.
Gonad Doses and Genetically Significant Dose from Diagnostic
Radiology. United States. 1964-1970. Washington, D.C.
Govt. Print. Off. April 1976. (DHEW-FDA-76-8034).

6/ Shleien, D. Tucker, T.T. and D.W. Johnson. Mean Active Bone Marrow Dose to the Adult Population of the United States from Diagnostic Radiology. Bureau of Radiological Health. (in progress).

Current Radiation Protection Standards,

Dr. Morgan.

Responsibility and Scientific Basis

I believe we had better go on to question 6. Let me state the question, and I will take a crack at one of the ans

wers.

Who must set the current radiation protection standards for public and occupational groups and what data are these standards based on?

First of all, I would like to indicate that for many decades the National Council on Radiation Protection and Measurements (NCRP) and the International Commission on Radiological Protection (ICRP) have set what sometimes are referred to as standards for protection from ionizing radiation through their numerous publications, but these, as has been indicated, are recommendations. I underline the word "recommendations."

Although these are not laws or official regulations or codes of practice, they in fact serve in many instances the function of regulations and codes of practice. In many cases, for example, the regulations that exist, the codes of practice are based specifically on these recommendations.

The first official guides at the Federal level in the United States, to my knowledge, were set by the Federal Radiation Council whose functions have now been taken over by the Environmental Protection Agency. There are many government agencies that have responsibility at the present time for setting radiation guides, standards, codes of practice, regulations. I might mention among others the former Atomic Energy Commission, now the NRC, the Environmental Protection Agency, the Bureau of Radiological Health, the Public Health Service, HEW, FDA, DOT (Department of Transportation), et cetera.

And of course, each branch of the military has its own regulations and the states and a number of local governments have regulations to control and assure radiation protection and to set standards.

And, addressing the second part of the question, by far the principal source of excessive and unnecessary population exposure is, in my opinion, medical and dental x-rays. With proper education and training, motivation, and certification, and with the use of improved equipment, I believe that this exposure could be reduced to less than 10 percent of its present level.

Even a 2 percent reduction in medical exposure would reduce population exposure more than could be brought about by completely eliminating the nuclear industry to the end of this century. The present radiation protection standards wherever possible are based on human experience -- the cause and effects of excessive exposure, most of which comes from excessive medical exposure.

However, in many cases, essential data are missing. In such cases, one must rely on animal studies. The most important human

depend are, for example, the human exposure history with radium that we have discussed and exposures of radiologists and other members of the medical professions to x-rays, studies of survivors of Hiroshima and Nagasaki atomic bombings, studies of medical patients undergoing radiation therapy, and the studies of Alice Stewart and many others showing a large increase in incidence of leukemia, central nervous system tumors, etc. as a consequence of the use of diagnostic x-rays on pregnant women.

I think again I might have encouraged some of you to respond to this question.

Dr. Ellett. I think I probably see the question somewhat narrower than you do. As you pointed out, the NCRP in 1958 made recommendations for radiation standards. In 1960, the FRC put out guides that essentially affirmed NCRP recommendations. They were also confirmed by ICRP in 1959.

If we have to say what data this is based on, we have to look at what data was available in 1959, not what data is available today. Recommendations, not standards particularly, have been reviewed since that time. The current situation is perhaps somewhat different than it was in 1959.

Certainly the occupational standard for radium was based on the industrial experience with radium workers and that is when there was a body of data available. As stated in the IRCP reports, nobody knew in 1959 if 5 rem per year was equivalent to the radium limits or not. I do not think that that sort of data became available until the publication, really of the BEIR Report. They did have an inkling in 1959 that there was increased leukemia, perhaps from Hiroshima and Nagasaki data, although that was not at all clear.

If you go back to 1958 and 1959 when the recommendations were lowered to 0.5 rem per year total for individuals in the general population, the main concern was genetic effects. People really started to believe that there was not a threshold dose, that there was harm as far as genetic effects were concerned. Almost no mention of cancer is made in the ICRP/NRCP study, but rather recognition that if you are going to expose large populations, you are going to have genetic effects and these effects are going to be with you, regardless of dose.

As to the danger of cancer occurring in the general public, I do not think there was much concern expressed in the recommendations. As near as I can find out, the philosophy was that doses should be ten times less for people who were not occupationally exposed. As the ICRP points out, we assume the occupational standards for radiation place radiation workers under risks comparable to other occupational hazards in industry. There was a balancing of risk against risk, if you will, so that there would not be something exceptional in the health effects observed in the radiation workers as long as their exposures were under NRCP/ICRP recommendations.

When it came to the general population, I don't know whether it is fair to balance an occupational risk situation as against

radiation dose. The way NRCP and FRC have handled this is to say the risk should be somewhat less, that is a factor of 10 less.

I don't know but that if we had a number system based on 20 instead of 10 it would be a factor of 20 less, rather than 10. I have never seen a real rationale for what dose we allow for the general public.

Dr. Morgan. I would take issue with some of the things you said. I was a member of NRCP and IRCP through all of these years and I was Chairman from the beginning of the Committee that prepared the internal dose report that you referred to. We did have access to some of the reports of the Hiroshima and Nagasaki survivors. We had access to some early data on the effects of exposure to the fetus, and we were particularly alerted to the human history on radium exposures; so much so that our standard was the 0.1 microcurie of radium in the body that corresponds to 30 rem per year. This was used in calculating the permissible dose for all the bone-seeking radionuclides.

We did look very carefully at the history of the exposures of the radiologist. That basically is where our present figure of 15 rem per year for most body organs came from. The British felt that the average exposure of early radiologists was of this order and that led us to have the two reference standards, namely 30 rem per year from radium 226 and 15 rem per year average exposure of the radiologist during the preceeding decades.

So we did have a great deal of this data for our evaluation. I remember Dr. Muller, the geneticist, and I worked closely together through these decades in preparing radiation exposure recommendations. We had many arguments on whether the genetic risks or the somatic risks set the boundary conditions for radiation exposure levels. And so these discussions went on for a decade at least before the ICRP reports themselves came out in print. Dr. Bond?

Dr. Bond. I should like to extend the remarks that you and Dr. Ellett made. I do not speak for the NCRP or the ICRP. With respect to the data, radiation standards have been based, historically on findings of scientific committees of the NCRP and ICRP. These councils attempted to call upon the best talent available to help evaluate scientific data.

In this country the NCRP has done this; in Britain, the MRC has done the same thing. At the time that fall-out was an issue, the British report was prepared and the so-called BEAR (Biological Effects of Atomic Radiations) Committee was prepared. This was in the middle 1950's.

As far as I know, as alluded to, it was the report of the genetic effects part of the BEAR Committee that had a great deal to do with standard setting at that time (mid 50's) and led fairly directly to the recommendation of the NCRP standard for the general public. In practice, this has been used very widely as the standard. It was the Genetics group of the BEAR Committee that stated, after a very careful review of the genetic effects data, the best available data at the time, that in their view, in

order to get the jobs done 10 rems over 30 years might have to be "allowed" as an upper limit. That included medical x-ray exposures. This evolved into 5 rem over 30 years or 0.17 rem per year for the general public for all man-made exposure except medical.

This was adopted as a recommendation for the general public and I would like to say that this committee stated very clearly what Karl Morgan also stated here -- that any numbers adopted as standards, are to be taken as upper limits, and that in fact the exposure should be kept to the lowest degree practicable.

Obviously, these committees used the best data available at the time they met. Later committees have been appointed and the information has been updated. The main point is that the groups having to do with radiation standards have attempted to avail themselves of the best data and talent available.

Dr. Morgan. Dr. Bertell.

Dr. Bertell. If that recommendation was that they be exposed to no more than 10 rem in a generation, then there was another assumption implied, namely that 5 rem would come from medical, and therefore you could distribute the other 5 over industry, is that correct?

Dr. Bond. Essentially correct, but not precisely. The precise figure, I believe, was three or four, and the rest for atomic energy. That evolved into recommendations for other groups that there should be allowed an upper limit of 5 rem for the public, over 30 years, from all sources other than medical exposure.

Dr. Bertell. There was an assumption there that we were getting about 5 anyway from medical sources, I think also in the beginning, Dr. Morgan, you said something about 73 millirads per year assumed medical exposure?

Dr. Morgan. This figure is a result of the Bureau of Radiological Health studies. In 1969, their data were evaluated and they came forward with the number 73 rem per year to total body of the average person in the U.S. from medical exposure.

Dr. Bertell. I would just like to give you the figures from the Tri-state survey on what people actually were getting on medical x-ray. This is over a ten-year, approximately ten-year period. Dr. Morgan. Excuse me, are these total body figures?

Dr. Bertell. Total body for medical x-ray, and that includes dental. The male controls averaged 10.37 rads in a ten-year period. The male cases 13.47 rads. Female controls, 11.7 rads and female cases 13.14 rads.

If we are talking about 10 rads over a 30-year period, we are already over this limit when we just talk about medical x-rays. In the DHEW Report of 1970 on the exposure to medical x-rays in the United States, the estimate I could come up with, as an average per person, was 642 millirem per year external from medical x-rays, not including dental.