Protective Methods in Radiology 267 



mendations is left to each country to deal with as appears to 

 it best." 



Most countries have, up to now, preferred not to take legisla- 

 tive measures. In Great Britain, the safety measures recom- 

 mended by the British X-ray and Radium Protection Com- 

 mittee ^^ receive the support of State Departments, such as the 

 Ministry of Health and the Ministry of Labor and National 

 Service, but those in charge of X-ray and radium departments 

 are not compelled to adopt the safety measures nor to submit 

 to inspection of their departments by the National Physical 

 Laboratory. The recommendations have, however, in general, 

 been followed by hospital authorities and factory managements, 

 while the manufacturers of X-ray equipment have played an 

 important part in the progressive improvement in conditions 

 by designing equipment and departments in conformity with 

 the committee's proposals. It may be mentioned that the Min- 

 istry of Labor and National Service issued an Order No. 703 

 on April 1st, 1942, regarding the health and safety provisions 

 for factory workers engaged in the use of radioactive luminous 

 compounds. The Order does not, however, specify any tolerance 

 doses, and the inspections of luminizing departments which are 

 carried out by the National Physical Laboratory on behalf of 

 the Ministry are based upon the tolerance doses suggested by 

 the British Committee. 



In the United States, safety recommendations are prepared by 

 the Advisory Committee on X-ray and Radium Protection. ^-^' ^ 



Tolerance Doses for Ionizing Radiations 



In toxicology, it is important^ to know what quantity of a 

 particular poison can be tolerated without ill effects. The same 

 position holds for ionizing radiations of all types, particularly 

 those of a more penetrating character, since complete protec- 

 tion against them is, in the light of practical considerations, 

 impossible. Before any protective schemes can be formulated 

 on a sound basis, it is necessary to survey the various types 

 of work undertaken with ionizing radiations and to have a com- 



