MONTE BELLO BOMBS

Press, Volume XCIII, Issue 28008, 30 June 1956, Page 11

MONTE BELLO BOMBS

Drift Of Radio-active Clouds Over Vast Distances DANGERS OF RADIATION TO THE HUMAN RACE [Associated Newspapers Feature Services) SYDNEY, June 25 The testing of atomic bombs in the Monte Bello Islands, the subsequent drift of radio-active cloud, and the appearance of radio-active rain near Cloncurry, Queensland, have given Australians sharp awareness of the dangers of radiation. In the following article, Dr. E. P. George, Director of the Experimental Research School of Physics, University of Sydney explains the effect of radiation on living tissue and discusses factors bearing on the dangers of radiation to the human race. He suggests the early establishment of a network of routine radiatioi monitoring stations throughout Australia.

Radiation is the name used to describe the transmission of energy over a distance through space.

Wireless, infra-red rays, light and ultra-violet rays are all examples of radiation which have biological effects if encountered in sufficient quantities, but they are not matters about which concern is expressed at the moment. What is of concern is the more penetrating type of rays given off by X-ray machines (X-rays) and radio-active substances. The latter can give off rays like X-rays. These are then referred to as gamma rays. They can also shoot off minute particles of two types known as alpha rays and beta rays. When X-rays and atomic rays are absorbed in living tissue they produce changes in the tissue cells, the nature of the change depending on the type of cell - , . , , Thus the cell may be destroyed, stimulated into more rapid growth and if sex cells, may be modified so that vie resulting offspring deviates from the normal. In the latter case a mutation is said to have been produced and mutations are usually retrograde—i.e.. as a result of a radiation-induced mutation, a moron is much more likely than a genius. The effect on the individual depends very much on the amount of radiation. Thus, consider the killing off of cells. In the normal wear and tear in the human being, cells are continually dying off and being replaced by new ones anyway, so that small doses of radiation, resulting in the killing of a few extra cells, hardly matter. The body can easily dispose of them. Similarly, a small stimulation of growth hardly matters and may even be beneficial if applied to accelerating the healing of wounds.

Similarly, mutations occur at a steady frequency in the human race independently of any radiation effects and. if the mutation rate is small compared with the natural one, it hardly matters.

In Large Doses

On the other hand, large doses of radiation will kill off cells at such a rate that the body is not able to dispose of them and poisoning ensues. This is radiation sickness and. if sufficiently intense, can be fatal. Similarly, excessive stimulation can produce cancer, and too large a radiation dose to the sex cells would result in large-scale degradation of the human race.

The all-important question is: What is a small radiation dose d what is a large one? To understand this we must have a yardstick with which to measure the effect. This unit of radiation dose is called the roentgen, after the discoverer of X-rays, and is roughly the amount of radiation you receive in one second at a distance of one foot from an average hospital X-ray tube. Lethal doses of radiation are of the order of 500 to a few thousand roentgens received over a short period of time—e.g.. a few weeks.

The time scale is important, as even the effects of several hundred roentgens can be harmless if received gradually over 10 or 20 years. Use is made of this fact in the treatment oi cancer by radiation, when the malignant tissue is killed off by a burst of X-rays or gamma rays. Cancer can be caused by a’constant irritation, and radition received regularly over a long period of time is one example of this. Doses of the order of 100 roentgens a year, continued for many years, are required to produce cancer.

In the case of mutations, a dose of about 100 roentgens ' results in a doubling of the natural mutation rate.

The effect is cumulative and the radiation received must be tallied up for the whole of the reproductive cycle—say. 30 years. On the other hand, the effect on the race must be calculated by averaging the radiation received over the whole population. As brought out in the report of the British Medical Research Council, it should be remembered that all our lives we are subject to a small radiation dose from cosmic rays, and from naturally occurring radioactivity in the ground This amounts to two-thousandths of a roentgen a week, one-tenth of a roentgen a year, or three roentgens in the reproductive cycle. It will be realised that this is so low as to be negligible—even genetically. In the recent atom-bomb tests, the background radiation at Marble Bar is reported to have increased by a factor of 30 for a few days, a similar increase being reported after rain at Cloncurry a few days ago. If this is so. it still only means sixtv-thousandths of a roentgen in a week, and it will certainly not last as long as that Again—negligible. In all these atom-bomb tests the great safety factor comes from the fact that the effects all die away in a lew days. It would be serious if the background increased by a large factor and stayed up. because of. say. the toofrequent occurrence of atom-bomb tests all over the world. The way to guard against this would be to establish regular radiation monitoring stations throughout the Commonwealth. At present, this is being done voluntarily and in a haphazard sort of way by a few isolated individuals and by universities. The time seems to be ripe for the establishment of a network of routine radiation monitoring stations. These would act like radar stations and give us early warning of a new and dangerous invader of our atmosphere: radiation. The cost of the equipment would be small —a few hundred pounds per station. Hence the Commonwealth could be covered for the expenditure of merely a few thousand pounds.