Chapter VI 



EFFECTS OF RADIONUCLIDES AFTER ABSORPTION 



The biological consequences of radiation originating from materials situated 

 within the body are fundamentally similar to those of external radiation. Important 

 differences stem from the facts that (1) radionuclides are not distributed uniformly 

 within the body, and (2) they serve as more or less continuous sources of radiation. 



A. Acute and Subacute Effects 



In animals, hematologic symptoms of acute radiation disease appear in seven to 

 ten days after the parenteral administration of lethal amounts of radionuclides^S, 24_ 

 Subacute effects, which are frequently seen between one and five months after administra- 

 tion of somewhat smaller amounts, may include hematologic and hematopoietic symptoms 

 as well as evidence of malfunction of those organs in which the radionuclide is most 

 heavily deposited. For example, plutonium and the rare earths lead to liver and bone 

 damaee radioiodine to thyroid damage, polonium to kidney damage, and radiostrontium 



pc; _9Q 



to bone damage "^ " . 



It is exceedingly unlikely that many human cases of acute or subacute poisoning 

 due to exposure to internal emitters will ever occur. In the event of nuclear war the 

 chance of serious damage from external radiation will greatly overshadow the chance 

 of damage from radionuclides that might enter the body. On the other hand, the long- 

 term effects of small amounts of these materials might become a serious problem. 



B. Chronic Effects 



Experience with the chronic effects of internal emitters in man is essentially 

 limited to radium, which has been used therapeutically and in the dial-painting industry; 

 to thorium, which has served as a contrast medium for roentgenographic diagnosis; and 

 to elements in the decay chains of radium and uranium, to which miners have been ex- 

 posed. An increased incidence of cancer has been observed in these groups of indivi- 

 duals"^"'^^. More recently radiophosphorus, radioiodine, and other new nuclides have 

 been used in treatment and diagnosis. So far, reports of tumor induction following use 

 of these therapeutic agents have been scanty. A recent follow-up study of patients 

 treated with 1^31 has failed to show an increase in the incidence of leukemia . 



In man, radium has produced epithelial tumors in the mastoid cavity and the ac- 

 cessory nasal sinuses, in addition to the usual sequela of bone malignancy^S. Tumors 

 may appear in those tissues in which the nuclide is located and also in adjacent tissues 

 lying within range of the radiation. Thus radiostrontium, which localizes in bone, 

 induces in mice both osteosarcomas and epidermoid carcinomas of the oral and nasal 

 mucosa^^. There is also evidence in this species that lymphocytic neoplasms may 

 result when tissues elsewhere in the body are irradiated-^ . 



The relationship between tumor induction and absorbed dose of radiation is ob- 

 scured by a series of problems that require individual solution. The basic difficulty 



