FREDERICK CANCER RESEARCH CENTER 
P.O. BOX B ■ FREDERICK, MARYLAND U S A. 21701 ■ 301 663-6000 
August 25, 1978 
Dr. Donald S. Fredrickson 
Director, National Institutes 
of Health 
Building 1 Room 124 
Bethesda, Maryland 20014 
Dear Dr. Fredrickson, 
We want to commend you and the recombinant DNA advisory committee on 
the proposed revision of the guidelines. We find that they represent 
a more realistic assessment of the potential dangers involved in 
recombinant DNA experiments than that made in the original guidelines. 
Accordingly, certain experiments are now exempt from the guidelines 
while both physical and biological containment requirements have been 
reduced to more appropriate levels. Furthermore, the review and 
approval of projects by the Institutional Biosafety Committee (with 
the exception of those requiring P4 containment) should eliminate many 
of the unnecessary delays that have occurred in the past. 
We would like to propose that the new guidelines should allow the 
substitution of the P3-EK1 containment level wherever the P2-EK2 
containment is specified (e.g. in the shotgun cloning of mouse DNA 
in prokaryotic vectors). The requirement for EK2 containment eliminates 
many of the genetic tools that are employed for selection and characteri- 
zation of cloned restriction fragments. 
With the exception of the change mentioned in the preceding paragraph, 
we would like to express our support for the proposed revision and 
acknowledge our appreciation for all of the work that you and the 
recombinant DNA committee have done. We remain 
Respectfully yours, 
Robert Yu 
Nat Sternberg 
Members of the Frederick Cancer 
Research Center Biosafety Committee 
:c*nf 
[A-49] 
OPERATED FOR THE NATIONAL CANCER INSTITUTE 
BY LITTON BIONETICS, INC. 
