Mr. HOLIFIELD. You are referring to prompt radiation there and not accumulated radiation over a period of time?

Mr. CORSBIE. I am referring to acute radiation.

Mr. HOLIFIELD. So the same amount of radiation received over a period of 30 days, of course, would not conform to this lethal dose rate? My question is this. You say that the lethal dose for 50 percent is 450 roentgens. The point I am making is that that refers to an acute or prompt dose of radiation. If that individual got that 450 roentgens over a period of, let us say, 10 days, it would be a different death rate, would it not?

Mr. CORSBIE. This quotation refers to days or months for the total dose. And I believe experience would indicate that the longer period over which the dose is received, the less hazardous it is.

Mr. HOLIFIELD. Is it not true that our experimental mammals such as mice have been able to take considerably more radiation over a period of time than they could stand in a one-shot dose?

Dr. DUNHAM. May I comment on that?

Mr. HOLIFIELD. Yes, Dr. Dunham.

Dr. DUNHAM. The best information we have now suggests that 450 roentgens given over a period of a few seconds, hours, or several days, would pretty much have the same effect.

You earlier said 30 days. Spread over a 30-day period, there would be much less effect.

Mr. HOLIFIELD. In other words, you would have to thin it out a little bit in order to keep it from having its cumulative effect? Dr. DUNHAM. That is right.

Mr. HOLIFIELD. That brings up the value, then, of 2 weeks, of a period of 2 weeks underground.

Dr. DUNHAM. That is the important thing.

Mr. HOLIFIELD. When your high radiation is in existence above the ground?

Dr. DUNHAM. That is right.

Mr. HOLIFIELD. And if you can protect the people during this period of rapid decay in the first 2 weeks, and they come out into an environment of 10 roentgens a day, or something like that, then you have a different situation. If they were exposed to rather heavy doses, the body can tolerate it and throw off to a certain extent its effects, due to the recuperative power of the body?

Dr. DUNHAM. There is recovery which sets in almost immediately. Mr. HOLIFIELD. It gives the blood a chance to restore the corpuscles that are killed by radiation, the prompt radiation.

Go ahead, Mr. Corsbie.

LETHAL DOSE

Mr. CORSBIE. The LD-50 is often given as 450 roentgens, that is, 50 percent of the people receiving that much of a dose would not be expected to recover. The LD-50 concept is widely used, and I sometimes believe it may be interpreted as "either you're dead or you're not."

Actually the 50 percent who survive will be very ill and their recovery will be slow.

Mr. HOLIFIELD. But if you step that up to 600 roentgens, then your LD rates would go up to almost 100 percent, wouldn't it?

Mr. CORSBIE. It would increase.

Mr. HOLIFIELD. How much would it increase? What is considered the average tolerance of the human body to prompt radiation? I know it will vary some by individuals, but what would you say, 600 roentgens-700?

Mr. CORSBIE. There are great differences of opinion, and I would like to refer this to Dr. Dunham, if I may.

Mr. HOLIFIELD. Dr. Dunham?

Dr. DUNHAM. Certainly somewhere between 600 and 800 roentgens acute radiation exposure would be fatal to practically any individual. There might be an occasional person who would survive.

Mr. HOLIFIELD. It would have more effect upon the young than the aged, would it not?

Dr. DUNHAM. Not necessarily; no.

Mr. HOLIFIELD. About the same effect?

Dr. DUNHAM. It would depend more on the state of health of the individual. There isn't that much difference in the different age groups.

Mr. HOLIFIELD. Thank you.

Go ahead, Mr. Corsbie.

CUMULATIVE RADIATION DOSES

Mr. CORSBIE. Although acute 150- to 200-roentgen doses will result in no acute effects in the great majority of people, this is not to be construed as a license for indiscriminate exposures until the dose has been accumulated. The values do give a means for making some assumptions with respect to feasible and economical shielding against radiation. They also point out the departure from the conservative peacetime standards which would be unusable in wartime and very likely for many years thereafter.

When we look at maps and diagrams of fallout patterns on which dose rates at various times are shown, we often see 1,000 roentgens per hour and other high levels indicated. After a couple of weeks the 1,000 roentgens per hour at H+1 hour will have fallen to 1 roentgen per hour or something in that neighborhood. The fact that the dose rate at 2 weeks is smaller by a factor of 1,000 does not mean that a dose rate of 1 roentgen per hour is nothing to worry about. Careful guidance from local officials and radiological know-how on the part of individuals and families will be required to minimize the effects of radiation.

DAMAGE TO STRUCTURES

Next I wish to add a few words about physical damage. Shelter from the weather would be important to us in wartime just as it is in peacetime, and we depend on a variety of buildings, facilities, and equipment.

Inside the range at which 30 pounds per square inch would occur we

should expect to find complete destruction of buildings except those which are specially constructed. Out to the 5-pounds-per-square-inch line and perhaps somewhat beyond in the event of megaton bursts we should expect to find wooden and brick homes destroyed. Aboveground tanks and commercial and communications facilities will be severely damaged in the 5- to 10-pounds-per-square-inch range.

Underground pipelines are quite well protected; however, the service connections are usually inflexible, and breaks can be expected to occur in profusion at the points where service lines enter buildings. Severe blast damage to automobiles occurs in the 5- to 7-pounds-persquare-inch range.

FIRE DAMAGE

Superimposed upon the blast damage or compounding it will be damage from fires. Under certain conditions small fires become mass fires which consume all combustible material. The annual fire loss exceeds $1 billion now when conditions permit fires to be fought with skill; the prospects in wartime give cause for deep concern.

PROTECTIVE DESIGN FEATURES IN CONSTRUCTION

I have a few observations pertaining to protection in a general way. If there is to be a nationwide effort, then the knowledge and skills present in cities and towns all across the Nation must be applied. There are data ready for practical applications in the hands of the professional people in architect's and engineer's offices, safety engineers, building developers, city engineering offices, and others who work in materials and design. They are the same people who are responsible for the engineering and design of physical structures today.

These data say, for example, that it is possible to design a one story wood rambler house which will provide as much shelter in the basement against fallout as we now find in a conventional two-story house. By substituting a concrete floor slab 6 to 8 inches thick with a 1/4-inch hardwood finished floor glued to it, for the usual wood beam construction, we may achieve a result equally pleasing in appearance to the homeowner, yet it improves considerably the protection against fallout. The windows in basements can be eliminated; we put them there before we had electricity to light and ventilate basements. We can use smooth roofs which will not hold the fallout particles. And we can exercise more care in using brittle, friable materials which convert under low pressure to damaging missiles.

INDIVIDUAL RESPONSIBILITY

It is necessary that the individual citizen evaluate for himself the kind and degree of protection best suited to his needs. As a very important first step he should be able to estimate what he has to start with, that is, to evaluate the protection available to him in his home, office, or factory and to exercise his judgment on the risk he is taking and to know how to reduce the risk and thereby improve his chances of survival.

A FAMILY AND HOME 25 MILES FROM A TARGET

Let us assume that a man lives about 25 miles from an important, somewhat isolated strategic target; that is, there is no other important target nearby. From a 20-megaton bomb, depending on the wind direction, and height of burst, this man could reasonably expect fallout dose rates upward of 3,000 roentgens per hour at early times, blast pressure of about 1 pound per square inch, and thermal radiation of about 8 calories per square centimeter. There would be no prompt radiation problems.

What does all this add up to in terms of the total hazard to the man and his family?

Prolonged exposure without protection from residual radiation, having an R+1 hour dose rate of 3,000 roentgens per hour would give an estimated infinity dose of about 19,800 roentgens; unprotected personnel would receive a lethal dose in less than an hour, or about 10,000 roentgens in 2 weeks. The 1-pound-per-square-inch blast pressure would shatter ordinary windows and doors and superficially damage other parts of a dwelling. The thermal injury to anyone who is unprotected, that is unshielded, would be characterized by second degree burns and, very likely, eye injury if he happened to be facing the explosion.

Survival depends on how much this man has found out about weapons effects, about the precaution he needs to take, and above all what he has actually done. For instance, a shelter with a shielding factor of 100 makes the radiation tolerable. Because of the slower rate of delivery of thermal energy from the high yield weapons, he can reduce effectively the number of calories hitting him if he ducks behind something opaque. After a few seconds the bulk of the thermal energy will have been emitted and he then has about 2 minutes to get to a place where he'll be safe from flying glass and other missiles created by the blast wave which travels at the speed of sound. Depending on the meteorological conditions, of course, the fallout could be expected to arrive in around 20 minutes to an hour and continue to fall for about 2 to 6 hours. Thus it can be seen that the effects of a detonation of 20 megatons as experienced at 25 miles do not confront our man simultaneously. If he knows the sequence of events, and if he knows what he has to do to survive, he has time to act. He does have to act correctly the first time or take the conquences.

At such distances few knowledgeable, intelligent people need be hurt seriously.

COST OF PROTECTION

I mentioned some examples of the protection we can undertake as we go along with new construction and new planning. Encouragement, perhaps insistence, is needed to stimulate practical applications while plans are still on the drawing boards Almost every time I talk about a shelter, the first question is: "How much does it cost?" Peo ple do not ask right away such questions as: "How close to the ground zero will the shelter protect my family?" or "Is a shelter really neces sary?" or "What do I need in addition to the structure?"

Once you have settled on the type of shelter that the local situation requires-once you have settled on the protection that the shelter

has to furnish-then is the time to get around to the costs of the different ways of getting the protection. But we cannot go by the cost alone.

Ten years ago and more there were protective measures which would improve one's chances of survival. The threat has multiplied, yet, if we do some things, we can still expect to keep the number of casualties down. Knowledge, practical applications, shelters, instruments, and good local organization are the basic components. With these and a resolute spirit the combined defenses will improve.

Mr. HOLIFIELD. Thank you very much, Mr. Corsbie, for this very fine presentation. This is going to be very valuable in helping us prepare our report.

Mr. Roback has some questions.

NATIONAL COMMITTEE FOR RADIATION PROTECTION

Mr. ROBACK. I would like to ask Dr. Dunham whether he is familiar with the report of the National Committee for Radiation Protection?

Are you familiar with that report, Dr. Dunham ?

Dr. DUNHAM. I assume, Mr Roback, you are talking about the one still in preparation which has to do with civil defense and was being developed at the request of the FCDA at the time the request was made?

Mr. ROBACK. Yes. Are you familiar with the findings in the report?

Dr. DUNHAM. I haven't seen a copy of it for some months. I think it is going through its final stages. As I recall, the purpose of the report is to try to give a feel for the amount of radiation exposure which people could tolerate. And it is a sort of general discussion of radiation. It doesn't get into the sort of thing that Mr. Corsbie presented, which is how much radiation is likely to occur at a specific distance from a specific type of weapon.

Mr. ROBACK. Well, in peacetime for industrial purposes, this committee tried to set up some dosage limits or criteria

Dr. DUNHAM. This is the other subcommittee.

Mr. ROBACK. I understand.

But this is an effort to do the same for wartime effects.

Now, do they come up with some specific criteria, or do they just admonish civil defense planners to keep down as much as possible the level of radiation received?

Dr. DUNHAM. I think they go a little further. Their basic philosophy is, don't take unnecessary exposure just because there is a war going on. But what they try to point out is that if you are a civil defense worker and deliberately take several hundred r, you may be a sick man and no use to the civil defense organization a couple of weeks later, and you had better try to keep it down as low as you can and not waste your radiation exposure, or your tolerance of radiation the first couple of days.

Mr. ROBACK. Does the Atomic Energy Commission act to review that report?

Dr. DUNHAM. I have reviewed it and commented on it. And I think Dr. Dunning also has had a chance to comment on it, and Dr.