THE PHYSICIAN AND ENVIRONMENTAL RADIATION HAZARDS
Genetic and somatic effects of radiation in children are discussed, particularly with respect to medical and fallout radiation sources. Only a small fraction of naturally occurring mutations can be attributed to background radiation ( approximates 0.1 rad/yr). The dosage required to double the mutation rate in man is estimated to be between 10 and 100 rad, with 15 to 30 rad as the most probable value for acute exposure and 100 rad for chronic exposure; however, physicians treating young patients have a special obligation to keep gonadal exposure to a minimum, since even small changes of the mutation rate have serious long-range biologic and social implications. It is pointed out that the problem of radioinduced mutations is so important that ill-advised statements concerning negligible radiation exposure should be disregarded. The Committee on Environmental Hazards of the American Academy of Pediatrics has recently issued a statement that assesses the genetic effects of fallout in Japanese atomic bomb survivors as nonexistent. It is suggested that this statement is erroneous and embodies a misleading limitation. A highly probable genetic effect has, in fact, been observed in exposed Japanese populations; namely, a change in the sex ratio of children of irradiated parents in the direction of fewer males. The misleading aspect of the Academy's report also ignores the recessive character of most radioinduced mutations. These would not be readily detected in the first generation, but would become apparent in future generations when homozygotes are produced. The principal sources of radiation exposure are listed and their relative contributions to hereditary effects are indicated. The order of magnitude of radiation doses associated with various diagnostic studies is tabulated. The average radiologic examination of abdomen and colon, including the fluoroscopy, contributes a gonadal dose of 2 rad, or approximates 20 times yearly background exposure. Relative importance of vari.ous fallout radionuclides in contributing to the exposure of children is assessed. Cesium- 137 and C/sup 14/ contribute the largest genetically significant dose; since the Sr isotopes are concentrated in bone and I/sup 131/ in thyroid, they contribute little radioactivity to the gonads. A survey of radiation doses attributable to fallout from weapons testing in 1954-61 is given. Carbon-14 contributes a large fraction of the radiation dose to gonads as well as to other tissues. Its effect is protracted; only 10% of the total dose attributable to it will be biologically effective by the year 2000. By contrast, all the Cs/sup 137/ from past weapons testing is expected to have exerted its activity by that time. Estimates of genetic damage resulting from C/sup 14/ released during weapons testing depend on whether only the present generation or all future generations are considered. Radioinduced carcinogenesis in children is considered, especially with reference to thyroid cancer for x rays and I/sup 131/. (BBB)
- Research Organization:
- Washington Univ., St. Louis
- NSA Number:
- NSA-18-003626
- OSTI ID:
- 4131966
- Journal Information:
- Pediat. Clin. North Am., Vol. Vol: 10; Other Information: Orig. Receipt Date: 31-DEC-64
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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