CARNEGIE INSTITUTION OF WASHINGTON 
Department of Embryology 
115 West University Parkway 
Baltimore. Maryland 21210 
TELEPHONE: 467-1414 
August 14, 1979 
Dr. William Gartland 
ORDA 
Bldg 31, Rm 4A52 
NIH 
Bethesda, Md. 20205 
Dear Dr. Gartland, 
I am writing in support of exempting recombinant DNA research that 
involves the use of laboratory E_. col i strai n K12, nontransmissible plasmids 
and lambdoid phages from restrictions more stringent than PI. Enough 
years have gone by, and evidence accumulated to confirm the abundant 
information that showed the inability of laboratory strains of E. coli K12 
to colonize the mammalian gut. These coli do not pass the "nontransmissible 
plasmids or lambdoid phage to other more vigorous bacteria in the gut. 
Attempts to absolutely guarantee that this will never happen cannot be 
made. However, the risk level is obviously so small that it is only 
reasonable to liberalize the rules governing research with these well 
understood and heavily studied host and vector systems. 
It has reached a point where further testing is essentially a waste 
of time. Critics of the research will continue to ask for more tests after 
each negative report. An enlightened approach must now accept the weight 
of evidence and liberalize these unecessary restrictions. 
I hope that you will pass this letter on to the committee that is 
evaluating this change in the Recombinant DNA Guidelines. 
Sincerely yours 
; 
Donald D. Brown 
Di rector 
DDB :GS 
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