1154 



RADIATION BIOLOGY 



Barlow (1918) was the first to report on the experimental induction of 

 carcinomas by means of radium. Although doubt was expressed as to 

 the neoplastic nature of the epithelial proliferative changes described by 

 him, his experimental pattern was followed by others who fully confirmed 

 his claim. The first "radium carcinoma" was described by Wakely 

 (1927) on the thumb of a man handling radium salts. In his first studies, 

 Lazarus-Barlow produced carcinomas of the skin in mice and rats (1918). 

 Later (1922) he reported on the induction of carcinoma of the gallbladder 

 by inserting radium into gallstones and placing such stones in the gall- 

 bladder. Investigations performed during the next two decades on the 



70-1 



050- 



Ld 

 O 



2 30- 

 o 



z 



10- 



Hh 



o o CONTROLS 



a a 2.2 r/8-HR DAY 



60- DAY INTERVALS 

 i0.ll r/8-HR DAY •— 

 i 4.4 r/8-HR DAY a— 



-• I.I r/8-HR DAY 

 -A 8.8 r/8-HR DAY 



Fig. 18-2. The incidence of leukemia in female mice after chronic total-body exposure 

 to 7 rays of radium (after Lorenz et ah, 1947). 



carcinogenic effects of radium, radon, mesothorium, and thorium are 

 surveyed in Table 18-2. 



Daels (1925) inserted radium into the subcutaneous tissue of mice and 

 rats, inducing sarcomas after seven to twelve months. About a year 

 later he described the induction of carcinomas by the same procedure. 

 Daels and Biltris (1931) soaked silk strings or tissues in radium chloride 

 solution, coated these with collodion, and inserted them in various tissues 

 of rats and guinea pigs, inducing sarcomas of the kidney, carcinomas of 

 the liver, and intracranial sarcomas after twelve to thirty months. The 

 similarity of action of this carcinogen to that of chemical carcinogens such 

 as methylcholanthrene, discovered later, is noteworthy. The type and 

 readiness of neoplasia induction seem to depend on the tissue, species, 

 and other factors, not on the carcinogen. When inserted in the kidney, 

 both chemical (e.g., methylcholanthrene) and physical carcinogens induce 



