PATHOLOGIC EFFECTS 29 



to direct its radiation to a particular part; in this way many of the early radiologists suffered 

 acute or chronic injury to the hands, which has also occurred in more recent atomic energy 

 accidents. 



In the second instance, a radioactive substance may be taken into the body and deposited 

 where it is a source of constant local irradiation until it is eliminated. Bone disease in radium 

 workers (leading to cancer as a late development) is a well-known example of this mode of 

 exposure. It is worth noting that the atomic energy industry, through careful preventive meas- 

 ures, has apparently avoided exposures leading to this type of injury. 



It is thus characteristic of the radiations that their effects may manifest themselves not 

 only immediately, but perhaps only after a long period of intermittent radiation, or may even 

 be long delayed after a single exposure. One of the particular tasks of the panel has been to 

 see all of these effects in a common perspective. They will be discussed here in terms of the 

 effects of radiation on the important organs and tissues of the body, since it is a well-known 

 fact that some are more readily injured by radiation than others, and that injury to some has 

 more serious consequences than to others. 



Blood-Forming Tissues*: Among the more serious effects of radiation are those on 

 the blood, since the vital blood-forming organs are particularly sensitive to radiation injury. 

 For example, when a man receives a total body dose of 200 to 400 r, the white blood cells 

 are decreased in number soon after radiation, and in fatal cases they almost disappear before 

 death. Other acute changes in the blood give rise to disorders in the clotting mechanism and 

 a bleeding tendency, and the formation of antibodies against infections is impaired. These 

 changes lead to acute illness in the second week heralded by decrease in the white cells. 



In the next few weeks anemias may occur due to deficiencies in red blood cell formation 

 and survival. Those victims living through the first month usually recover, but in certain in- 

 dividuals, or where radiation is continued, there is a further serious breakdown of blood cell 

 formation. 



A late effect of radiation appears to be leukemia, which may arise years after radiation 

 exposure. This disease, relatively rare in man, may show manifold increase in population 

 groups, such as bomb casualties, subjected to intensive radiation over a short period of time 

 or in those whose professional work has exposed them to higher than acceptable permissible 

 doses. 



In a British study, the incidence of intrauterine exposure to X-rays used to take roent- 

 genograms was determined in two groups of children, one dying of leukemia and other cancers 

 and the other without malignant diseases. It was observed that a larger proportion of the 

 former group were so exposed. Of several regional studies in America, some confirmed these 

 observations but others have not. Because of difficulties inherent in epidemiological studies 

 of this type, particularly with regard to the selection of non-irradiated controls, it is felt that 

 further investigation will be required to establish whether or not diagnostic radiation is leu- 

 kemogenic to human embryos. 



Gastro-intestinal Tract: Effects on the intestinal tract are also critical in the early pe- 

 riod. Vomiting and diarrhea occur within a few hours. This is a common complication of 

 X-ray treatment to the abdomen. It seems to be mediated through the vegetative nervous 

 system and is probably not related to later damage. 



Within a few days (usually four or five) after a person's whole body is exposed to 200 



* An interim statement of the Subcommittee on Acute and Long-Term Hematological Effects is presented 

 in Appendix A herewith. 



