HAZARDS OF RADIATION
A recent report of the U.N. Committee on the Effects of Atomic Radiation is discussed with emphasis on the genetic damage that follows any dose of radiation, however small. It is pointed out that it will be many years before clear-cut technical resolution is possible, but recent work indicates that as knowledge increases so does our awareness of the deleterious effects of even low doses of radiation. Everyone is exposed to radiation from natural sources of about 100 mrad per yr, which varies by 20% from place to place in the British Isles. It is approximately the same for the dose to the bone marrow, significant as a somatic target, and for the gonads, significant as the genetic target. It is roughly estimated that this level might be producing about 10% of some of the neoplastic diseases which occur naturally, e.g., leukemia, as well as 10% of the new mutations added to the pool of genetic damage. On this estimate, and on a linear type of dose-response relation, can be based the decision whether additional radiation exposure is justified either to an individual or to a population in the light of the risk involved. So far as the genetic effects are concerned any additional radiation exposure increases the risk of genetic damage in the population, and the genetically significant exposure of the population must be kept to a minimum. For those occupationally exposed, a different criterion has been used, and a so-called permissible level has been established. With increasing knowledge of the effects of radiation, the limit of this permissible dose has been decreased from 100 rad/yr in 1928 to 15 rad/yr in 1947, and more recently to 5 rad/yr. For the general population, the permissible dose is 10% of this. Similar reductions have been made in the maximum permissible radioactivity in foodstuffs. This trend of increasing caution with increasing knowledge is likely to continue, it is inferred. Even tracer doses of tritiated thymidine incorporated in the nucleus of leukemic lymphocytes may increase their ability to induce leukemia. The data are summarized relating to the possible effects of radiation on the fetus. It is concluded that pelvic x irradiation should be discouraged except during the 9 days after the onset of a regular menstruation, as a simple precaution which could be instituted more widely in medical practice. The genetic consequence of fetal irradiation also is discussed as a problem different from that of the adult. A study of 734,243 children indicates a cancer-mortality rate 40% higher in those prenatally x rayed than in the non-x-rayed population. The mean dose to the fetus was of the order of 2000 mrems, given at one time, that is, 20 times the background level spread out over a year. From these figures it is estimated that the doubling dose for these late somatic effects in the fetus is of the order of 6 rad, about 1/5 of that estimated by the United Nations Committee as the doubling dose for similar effects in the adult. Several other reports relating to growing radiation hazards are discussed. (RBB)
- Research Organization:
- Originating Research Org. not identified
- NSA Number:
- NSA-18-009935
- OSTI ID:
- 4084840
- Journal Information:
- Brit. Med. J., Vol. Vol: 2; Other Information: Orig. Receipt Date: 31-DEC-64
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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