THE INSTITUTE FOR CANCER RESEARCH 
TTOl BlIBHOLME AVENUE 
FOX CHASE • PHILADELPHIA, PENNSYLVANIA 10111 
215 FIDELITY 2- lOOO ■ cable address, can search 
December 14, 1979 
Dr. Donald S. Fredrickson 
Director 
National Institutes of Health 
Bethesda, Maryland 20014 
Dear Dr. Fredrickson: 
I am writing this letter to let you know that I fully support your 
position that all recombinant DNA research performed with E. coli strain 
K12 should be classified P1/EK1. I feel that the potential risks of such 
research have been carefully evaluated by well-informed specialists and 
that this classification is a proper one. 
Yours very truly 
Kenneth D. Tartof 
KDT : Is 
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