Suggested reduction of permissible exposure to plutonium and other transuranium elements.

The historical development of the value of maximum permissible body burden ot 239Pu is presented and present considerations for the revision of this standard are given. Some evidence is presented that the linear hypothesis may not be sufficiently conservative at low dose rates and especially for the actinide elements. Until certain questions are answered about the particle problem, it will not be possible to set a satisfactory maximum permissible body burden for 239Pu based on lung as the critical organ, but in the meantime some studies suggest that the present maximum premissible body burden based on bone should be reduced at least by a factor of 200.