THE INSTITUTE FOR CANCER RESEARCH 
7701 BUBHOLME AVENUE 
FOX CHAS E • PHILADELPHIA, PENNSYLVANIA 10111 
215 FIDELITY 2 - lOOO • CABLE ADDRESS: CANS E ARC H 
December 13, 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 
rpp/b 
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