230 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1953 



isotopes and their applications as tracer atoms in the twentieth cen- 

 tury has given us a tool whereby we can explore the physiology and 

 biochemistry of organisms in the dynamic state with even greater 

 detail. The microscope permits examination of the structural details 

 of individual cells. Isotopes permit examination of the chemical 

 activities of individual batches of molecules, atoms, and ions within 

 cells. 



The isotope, particularly the reactor-produced radioactive isotope, 

 has truly been a new key to knowledge. It is a key that has already 

 opened up many doors. Many many more, however, remain to be 

 opened and can be opened by this new key. 



EXAMPLES OF APPLICATIONS 



Keactor-produced radioisotopes have been used, particularly as 

 tracer atoms, in nearly every phase of the physical, chemical, and 

 biological sciences. They have also been used extensively in many of 

 the applied problems of medicine, agriculture, and industry. Since the 

 distribution program began in the summer of 1946, more than 32,000 

 radioisotope shipments have been made from the principal produc- 

 tion facilities in Oak Ridge, Tenn., to some 2,000 departments of over 

 1,200 institutions throughout the United States. In addition, more 

 than 1,600 shipments have gone to approximately 360 institutions lo- 

 cated in some 33 foreign countries. Also, several thousand shipments 

 have been made from secondary commercial suppliers in the form 

 of specially processed radiomaterials, radioactive drugs, radiation 

 sources, etc. 



In the past 6 years somewhere between 4,000 and 5,000 papers and 

 reports dealing with isotope investigations have been published in 

 some 200 different scientific and technical journals. These only in- 

 clude papers on work done with Commission-supplied isotopes. Also, 

 a number of books have been written on the subject. 



Since the number of different kinds of applications could run into 

 the thousands, we shall try to select examples representative of a large 

 number of applications. Also, to keep the story short, we shall stick 

 to applications in medicine, agriculture, or industry. 



MEDICINE 



The largest percentage of radioisotope shipments go for use in the 

 field of medicine. This is not only because radioisotopes are used 

 extensively in medicine but because most medical applications use 

 short-lived radioisotopes and therefore require repeated shipments. 

 Radioistopes have foimd valuable uses in medical research, diagnosis, 

 and treatment. 



