THE INFLUENCE OF STRONTIUM-90 UPON LIFE SPAN AND NEOPLASMS OF MICE
Predictions of the potential hazard to man of worldwide contamination with sdtrontium-90 must be based largely upon the results of animal experimentation. Among the most useful criteria of radiation damage to in life span and increase in the incidence of certain tumors. However, these effects can be studied and evaluated adequately only when large numbers of animals are observed for the duration of their natural lives. The mouse is admirably suited to this type of experimentation. Although the human problem is primarily one of depositon within the body of material that has been ingested or inhaled, extrapolations from mouse to man are simplified if the radiostrontium is given by intravenous injection because of species differences in absorption At low levels thc effective dose is probably that which becomes incorporated in the skeleton rather than that which passes through the gastrointestinal tract or lungs. Differences in uniformity of distribution, depending upon whether the period of exposure is relatively short or long, have been studied by administering the total dose in a single injection or in multiple, fractionated injections. The twelve dosages administered to 1320 CF No. 1 female nice ranged from acutely lethal levels to one that resulted in a body burden corresponding to approximately 10 mu c/man, or to 10 times the present maximum permissible level for occupational exposure. The control population consisted of 240 mice. Neither the average life expectancy nor the timne to 50% mortality plotted against the dose resulted in curves that could be described adequately by a simple linear function or by any of a number of mathematical transformation. At the three lowest levels the differences in survival between the experimental and the control populutions were within the range of expected variation A statistically significant difference in life expectancy was not seen below a dose roughly equivalent to 350 mu c/man The data on osteogenic sarcomas similarly failed to demonstrate a linear dose-response curve, and the number of such neoplasms arnong the 3 lowest dosage groups fell within the control range. Thus life span and malignant tumors of bone appeared to be equally sensitive indicators of radiation damage. Neoplastic change of the blood-forming tissuss, however, proved to be a more sensitive criterion of injury. Although the incidence of reticular tumors was not markedly influenced by radiostrontium, they appeared earlier as the dose increased. The time required to reach a 20% incidence was significantly shorter among the animals that had received 8.9 mu c/ kg than it was among the control animals. This injected dose resulted in a body burden of approxirnately 1 mu c/kg, which is roughly equivalent to 70 mu c/man. Below this level the treated animals were indistingishable from their controls. Since the differences in life span and neoplasms of bone and reticular tissues among the lowest doses and the control population were not statistically signifi- . cant, it appears either that pathological change in the total mammalian organism is too crude a measure of toxicity at very low levels or that such levels actually are without effect.(auth)
- Research Organization:
- Argonne National Lab., Lemont, Ill.
- NSA Number:
- NSA-12-014505
- OSTI ID:
- 4310408
- Report Number(s):
- A/CONF.15/P/911
- Resource Relation:
- Other Information: Prepared for the Second U.N. International Conference on the Peaceful Uses of Atomic Energy, 1958. Orig. Receipt Date: 31-DEC-58
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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ANIMALS- BLOOD FORMATION- BODY- BONES- CANCER- CARCINOGENESIS- DIAGRAMS- MAMMALS- MAN- MATHEMATICS- QUANTITY RATIO- RADIATION DOSES- RADIATION EFFECTS- RADIOSENSITIVITY- SARCOMAS- STATISTICS- STRONTIUM 90- SURVIVAL TIME- TISSUES- TUMORS- VARIATIONS- WEIGHT
BLOOD CIRCULATION- BODY- BONES- CARCINOGENESIS- CONFERENCE- CONTAMINATION- DISTRIBUTION- ENVIRONMENT- INTESTINE- LETHAL DOSE- - LUNGS- MAN- METABOLISM- MICE- RADIATION DOSES- RADIATION EFFECTS- RADIOSENSITIVITY- SEX- STRONTIUM 90- VARIATIONS