HEALTH PHYSICS AND RADIATION PROTECTION 103 



topes in this category. If these materials are to be put into the sewer, it 

 has been suggested by Quimby (50) that they be dihited with enough of 

 the stable isotope in the same form to give a dihition such that a constant 

 intake could not give more than the maximum permissible body burden. 

 This may be theoretically calculated from the maximum permissible body 

 burden and the total amount of the element in the body. However, this 

 approach should be used with caution, especially in the case of the bone- 

 seeking radioisotopes that may be accumulated in the skeleton by the 

 exchange process under nonequilibrium conditions. Quimby has also 

 suggested that water dilution to a concentration ten times that permitted 

 for constant ingestion would be a realistic and adequate procedure. 



Especially for the remains and excretions of large animals, it would 

 seem that burial in soil offers the most practical approach. Most agricul- 

 tural institutions where this type of work is done would have some small 

 areas of land that could be set aside for the purpose. The burial ground 

 should be under the long-term control of the institution, and permanent 

 records should be kept of the amounts and materials buried. The area 

 should be fenced off and plainly marked. Such factors as the level of the 

 water table, the final pathways of wastes, and the burial capacity will 

 be of importance in the choice of the site. For specific elements the 

 exchange capacity and nature of the soil may be used to estimate the 

 amount of diffusion to be expected. The behavior of elements incor- 

 porated in soils has been the subject of much study by soil scientists, who 

 may be called on to offer specific recommendations for local conditions. 

 Soil and vegetation samples can be measured occasionally to determine 

 the possibility of the spread of radioactive material. The radioactive 

 wastes may be buried in pits or trenches, either with or without prior 

 enclosure. If the waste is contained in a relatively small volume, enclos- 

 ure may be preferred. This may be accomplished by using a pipe of 

 appropriate diameter, sealed at one end and set vertically in the ground. 



Burial at sea after incorporation in concrete or return to the Atomic 

 Energy Commission is possible but will usually not be necessary under 

 ordinary conditions. 



Longer-lived isotopes in sealed sources used chiefly for external irradia- 

 tion (such as Co^", Sr^", and Ta^^^) should be returned to the supplier for 

 disposal. 



Carbon 14. General recommendations have been proposed for the 

 disposal of wastes containing carbon 14 which are considered to be very 

 conservative with respect to the health hazards involved, and at the same 

 time very Uberal in regard to the needs of the users (9). The tremendous 

 dilution of the disposed C^^ with the carbon of the biological cycle makes 

 it possible to have such liberal recommendations. There are two cases, 

 however, which are not covered by the general proposals and to which the 



