Yale University 
Neiv Haven, Connecticut 06510 
SCHOOL OF MEDICINE 
333 Cedar Street 
Department of Human Genetics 
December 11, 1979 
Dr. Donald S. Frederickson, Director 
National Institutes of Health 
Bethesda, Maryland 20205 
Dear Don: 
I am writing to express my strong support for the wording of the 
proposed revised recombinant DNA guidelines as published in the Federal 
Register of November 30, 1979. In particular, I wish to endorse the 
new Section III-O on page 69 218, dealing with experiments using E-coli 
K12 as host. 
As a member of RAC from its formation until June, 1978, chairman of 
the RAC sub-committee on EK2 host-vector systems, and chairman of Yale’s 
Institutional Biohazards Committee, I've had ample opportunity to review 
the evidence that has been presented by persons of many different viewpoints 
concerning the safety of recombinant DNA experiments. Based not only on 
theoretical arguments, but on solid data concerning strain K12's lack of 
potential for pathogenicity or for transmission of vectors to other hosts, 
I can see no hazard to either laboratory workers or to the general public 
in the conduct of recombinant DNA experiments using K12. 
I, therefore, urge adoption of Section III-O, as a way of eliminating 
a costly and time-consuming unnecessary obstacle to research of great 
practical importance as well as scientific interest. 
Sincerely yours 
EAA:ml 
E 
P lenetics 
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