THE WISTAR INSTITUTE 
THIRTY-SIXTH STREET AT SPRUCE 
PHILADELPHIA. PA. 19104 
HILARY KOPROWSKI. M.D. 
Phone: (215) 243-3700 
DIRECTOR 
CABLE ADDRESS: WISTARINST 
December 19, 1979 
Director 
National Institutes of Health 
Bethesda, Maryland 20205 
Dear Sir: 
I consider a progressive downgrading of the containment require- 
ments for recombinant DNA as necessary and important so that the guide' 
lines reflect realistically the real dangers. 
Yours sincerely 
PJC: eg 
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