ATTACHMENT 4

INTER-OFFICE MEMORANDUM

To: Mr. J. R. Oppenheimer

From: L. H. Hempelmann

Subject: Danger to Personnel from Inhaled or Ingested Plutonium

This question was first raised by Mr. Kennedy in view of the fact 
that large quantities of the dry material will be worked with in this 
laboratory. The biological damage in the following cases will be local 
in character, and will be produced by the energy absorbed by the tissues 
from alpha particles emitted by the plutonium.

Case I: Inhalation of plutonium dust with deposition of the material in 
the bronchial epithelium.

			FOR REFERENCE SEE (11bb01)

This exceeds the daily tolerance limit of radiation even for a single 
irradiated organ.

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Case II: Ingestion of plutonium (assuming that absorption from 
intestinal tract and subsequent metabolism is the same as in the 
case of radium).

2-10 micrograms of radium deposited in the bones is known to be fatal 
over the course of years. If 1/50th. as many alpha particles are 
emitted by plutonium, than 100-500 micrograms would constitute the 
lethal dose of plutonium.

Carbon copies to: Mr. J. Kennedy
Mr. C. Smith