ation by going down deep in a mine where no cosmic radiation can penetrate. This still will not solve the radiation problem, because there he will be exposed to radiation from radioactive material in the earth's crust. Some of these radioactive materials are, therefore, found in materials used to construct buildings. In addition, there are radioactive elements within the make-up of all persons' bodies, elements that have been radioactive from the beginning of time, such as radioactive potassium, radium, and carbon. A person's body also tends to concentrate radioactive materials that are taken into it, particularly from the water which he drinks. Water, in some parts of the country and particularly from some mineral springs, has appreciable radioactivity. So, from the beginning of time, man has been exposed to an inescapable natural background of radiation.

In addition to this natural background of radiation, the population as a whole receives a certain amount of radiation from medical and dental diagnostic and therapeutic procedures. It is obvious, from a basic premise that radiation can damage living tissue, that some of this medical and dental radiation may have some harmful effects. When harmful effects appear to outweigh the benefits from medical use of radiation, the logical course is to modify the medical procedure, not do away with all medical uses of radiation.

People are exposed to radiation from X-ray machines for the purposes of determination of broken bones, diagnostic techniques for the proper functioning of body organs, detection. of lung diseases, and many others. Such devices have been in use for the past 50 years. These are machines which produce a man-made form of electro-magnetic radiation similar to gamma rays (fig. 22). An example of unnecessary exposure to radiation is the use of shoe-fitting fluoroscope machines which fit children's shoes by the use of X-rays. These are a possible hazard, not only to the child, but also to the shoe clerk. No useful purpose is served which could not be served by other means, and in many jurisdictions these devices have been outlawed.

Probably the chief error in much of the current thinking about radiation hazards is the failure to relate radiation hazards to the other hazards of human existence. All human activity

involves risks. Some of them are physical, such as the hazard of being hit on the head by a heavy object dropped from above. Some hazards are more mental than physical, such as those of the advertising executive or play producer, who is under the constant strain of delivering completely satisfactory work or suffering the penalty of being ruthlessly eliminated from the field of his chosen profession. Consciously or not, when a person selects a field of work, he makes an appraisal of the hazards involved, along with the other factors, such as pay, general working conditions, prospects for advancement, and security of employment, all of which must be considered. Each occupation has its own peculiar hazards, inherent in the nature of the work. In controlling the hazard, attempts are made to reduce the probability of accident to a minimum, but absolute freedom from risk cannot be guaranteed.

the fact that serious diseases can be spread from person to person by improperly washed tableware. Yet most people would consider a man who went into a restaurant and applied a sterilizing solution to the tableware before using it, to be somewhat neurotic. In general, they have weighed the risk and found that it is so slight that they prefer to ignore it. However, if a violent epidemic were to break out in a city, the inhabitants might well consider that they should take precautions.

When driving on the highway, despite the fact that many people might maintain their own automobiles in perfect mechanical condition, and despite the fact that they might be truly defensive drivers-mentally driving not only their own cars but also the cars of others— situations can arise in which they, and those dear to them, can be maimed or killed under circumstances entirely beyond their control. The only control over this is to stay at home. Yet, while thousands are killed and maimed on our highways, few people refrain from driving automobiles or riding in automobiles because of the terrible accident toll. Having weighed the hazard against the good, the motoring public has made its decision.

If a man doesn't care to accept the exposure to radiation incidental to employment in an atomic energy plant when all of the necessary precautions have been provided and his radiation exposure is no more than the maximum permissible level, there is only one thing for him to do; he should find other work, the hazards of which he is willing to accept.

Many occupations are fraught with so-called "calculated risks." Regardless of the risks involved most people work safely at these occupations all their lives. This is simply because they have learned to recognize, plan for, and live with the hazards. Fire fighting is a hazardous business which firemen have learned to accept and live with.

When addressing a group of citizens such as the PTA on the subject of fire protection, a fireman would always give them one firm piece of advice: "If your house is on fire, get yourself and your family out of the house immediately. call the fire department, and do not go back into the house." When this fireman arrives at the fire he immediately enters the burning building.

This is directly contrary to the advice he gave the citizens, advice based on the fact that it i dangerous to remain in a burning building Then, why is he entering the building? To save life? Not in this case because upon arrival he was assured that all persons were out.

He entered the burning building because it was part of his job to confine the fire and lim: the destruction. In so doing he took risks, bu because of his training and experience he knowthese risks are reasonable, considering the objective. He would not, however, enter all burning buildings indiscriminately. Little risk i taken by a fireman in fighting a fire in a dilapi dated barn. A greater risk is taken by a firemar in fighting a fire in a commercial building. The greatest risk is taken by a fireman in saving lives during a fire in an occupied building.

Firemen must learn to relate radiation hazards in their proper perspective to the other common risks which they face. In addition, thes must also learn to adjust their radiation risk acceptance to the necessity of the job to be accomplished.

When firemen have been educated in a sour! approach to the hazards of the Atomic Age. they will take the same reasonable view of these hazards that the people working in a radiation plant do, and the same view they take regarding the other hazards of their professior

The safety record of the Atomic Energy Commission program is phenomenally good. The fatal accident rate is less than half that of the best of American industry. Although approx:mately 200 people have been killed in the program, only 3 deaths resulted from accidents involving radiation. The others were killed ir what are sometimes referred to as "normal" industrial accidents, such as fires, falls, electrocutions, motor vehicle accidents, drowning, and the like.

The effects of excessive radiation exposure or the body are manifested in several ways:

In add to the three noted above shortly before p three military personnel were killed in a criticality accident 1g the SI 1 reactor seated at the National Reactor Test Sa's m Jako ka'a Tah The deaths apparently did not resa” direc TTT! ra: " but frn ma ve physical injuries caused by 8!་x༅%Tiམ༞༞༞pp!£ *a *v{»« tZwn®% There is little dut that had they survived the effects of the explain they w have received masove radiation doses which would have here fa'a

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Radiation Sickness

This is a sickness produced by a massive overdose of penetrating external gamma radiation, which causes nausea, vomiting, diarrhea, malaise, hemorrhage, and a lowering of the body's resistance against disease and infection, and, of course, if serious enough, can cause death.

Radiation Injury

Radiation injury consists of localized injurious effects, generally from overdoses of less penetrating external beta radiation and most often to the hands because contact is usually with the hands. This can cause injuries not unlike burns, loss of hair, and skin lesions. Genetic damage is also a form of radiation injury, usually of permanent nature.

Radioactive Poisoning

Radioactive poisoning is illness resulting when dangerous amounts of certain types of radioactive materials enter the body; it may cause such diseases as anemia and cancer. The alpha radiation emitters are the most dangerous in this respect.

After looking at the foregoing, one realizes that a fireman can get into trouble with radiation by two entirely different means. One, by radiation originating from a radioactive source located outside the body from which the radiation comes at the body like a continuous shower of tiny, invisible bullets; the other by exposure of internal body organs to radioactive material which has been taken into the body and which may have collected in these body organs. It should be obvious that precautions against one type of hazard will not be particularly helpful in protecting against the other type of hazard, and that the radiation problem is made up of two separate problems (fig. 23).

This is indeed the case. As a matter of fact, certain radioactive materials are no hazard at all outside the body. However, if these same materials got inside the body in sufficient quan

External Radiation

HERE ARE TWO TYPES of external radiation hazards: (1) long-range, highly penetrating external radiation called gamma; and (2) shortrange less penetrating external radiation called beta.

The long-range, highly penetrating external radiation is similar to X-rays, and consists of very short waves of pure energy having no mass or weight. These rays originate from certain radioactive materials which are usually located outside the body, and so the rays come at the body like a continuous shower of tiny, invisible bullets. In order to visualize this, it should be thought of as one ray at a time. Each ray can be considered a bundle of energy. It may penetrate the body to some depth before it does damage and the energy of the ray is spent. (The effect of radiation on the body is a little more complex than this, but this concept will serve the purpose of this text.)

Observe the figure of the man in figure 24. The rays come at him from the radioactive source which is giving off the penetrating gamma radiation. Each ray penetrates to a different depth in the body before finding its target and producing its effect on the structure of the body. Also note that a sizable proportion of the radiation passes through the man's body. Those rays that pass entirely through do him no harm.

If it were not for the fact that some radiation can pass through the body without touching it, X-ray pictures would be impossible. For example, the X-ray machine is pointed at the patient's chest and the film is placed at his back. If his body stopped all of the radiation, there would be no radiation left to reach the film. It is obvious that some of the radiation gets through to the film.

Roughly speaking, 85% of the human body is composed of water. Figure 25 shows a concept

of what this water might look like if it could be magnified with a microscope tremendously more powerful than any in existence. Of course it must be realized that there are many other elements and compounds in the body which are not shown for simplicity's sake.

It is general knowledge that water is HO. This means that the water molecule consists of an atom of oxygen with two atoms of hydrogen tied onto it. Each one of the figures in the illustration represents a molecule of water. It has been seen that atoms consist of two parts, a heavy dense core called the nucleus, which contains practically all of the weight, and very tiny particles called electrons that spin around the nucleus like the planets around the sun.

The trouble with the illustration is that it is not to scale. If the nuclei of the atoms were actually as big as shown, the electrons would be whirling around hundreds of feet away and would be the size of tiny specks of dust.

It can be seen that if the electrons are this far away from the nucleus, the nuclei of the various atoms must be relatively quite far apart. This is the case. Yet, when one steps on a weighing scale, what is being weighed is the sum total of all the nuclei in the body, those little incredibly heavy balls of matter existing mostly in empty space. These nuclei are so heavy that if a child's marble could be made. of this material only, it would weigh 37 million tons.

Therefore, it now can be understood how it is possible for each ray to penetrate various distances into a substance before it hits anything and that some rays will pass entirely through the substance because it is mostly empty space.

The rays from radioactive materials do not hit the nucleus in significant numbers; few of them have enough energy to penetrate this central ball of matter and cause any change. They do hit the electrons, which are spinning around. the nucleus, and the energy of the ray is spent. This results in a transfer of energy from the rays to those electrons which are ejected from the atoms. This process is called ionization.

ment and rearrangement of these electrons as shown in figure 26, positive and negative ions are created.

Atoms in their normal state are electrically neutral, that is, an atom contains the same number of electrically negative electrons in orbit as it contains electrically positive protons in its nucleus. When radiation causes displace