The Johns Hopkins Oncology Center 
Biochemical Virology Laboratory 
301/955-8900 
December 21, 1979 
Dr. Donald Fredrickson, Director 
NIH 
Bethesda, Maryland 21205 
Dear Dr. Fredrickson: 
This letter is written to support the proposed downgrading of the containment 
level for the recombinant DNA experiments when E. coli K12 is used as outline* 
in the Federal Register, November 30, 1979. I support this proposal, since I 
am personally involved in the cloning experiment, and our data as well as the 
work from the other laboratories indicate that the recombinants are much less 
stable than anticipated. This and the results of the risk assessments experi- 
ment indicate that there is much less biohazard involved than originally 
thought. Therefore, I personally believe that all of the regulations imposed 
on laboratories working with E. coli K 12 host vector system are not only not 
necessary but also increase enormously the cost of these experiments. 
The downgrading would not only allow rapid progress in these areas of 
medical application but also decrease the experimental cost. 
Yours truly, . 
Paula M. Pitha, Ph.D. 
Associate Professor, Oncology 
Assistant Professor, Microbiology 
mas 
601 North Broadway, Baltimore, Maryland 21205 
[566] 
