UNIVERSITY OF WASHINGTON 
SEATTLE, WASHINGTON 98195 
School of Medicine 
Department of Microbiology and Immunology , SC-42 April 19, 1978 
Dr. Donald Fredrickson 
Di rector 
National Institutes of Health 
Bethesda, Maryland 20014 
Dear Dr. Fredrickson: 
I am writing you following my return from Europe after attending the 
International Symposium on Genetic Engineering held in Milan March 29-31, 
1978 and the Plasmid Workshop held in Berlin from April 1-5, 1978. During 
the course of the meetings I consulted with a number of scientists about 
your request to prepare a documented list of microorganisms which are known 
to readily exchange genetic material under laboratory conditions or in Nature. 
I am glad to tell you that this material is being collated for transmission 
to the Recombinant DNA Advisory Committee. 
On March 30, 1978 Professor E. S. Anderson, Professor M. H. Richmond and 
I held a meeting (our second) on Rick Assessment under the auspices of the 
Committee on Genetic Experimentation (COGENE) which was formed by the Inter- 
national Council of Scientific Unions. It was our unanimous concensus that 
we now have available sufficient data in man and livestock to show that: 
a) the survival of _E. col i K-12 sublines in man and animals is exceedingly 
low; 
b) the frequency of transfer of self-transmissible plasmids from K-12 to 
resident gram negative flora of man occurs very rarely indeed; 
c) that the frequency of transfer of plasmids from the resident flora to 
fed E_. col i K-12 strains is extraordinari ly low and; 
d) that the frequency of mobilization of non-conjugati ve plasmids (the 
type actually used in DNA recombinant experiments) from K-12 to other enteric 
flora is not detectable under normal circumstances. 
The combined monitoring data of several laboratories over a three year 
period has failed to demonstrate the colonization (indeed not even the detection) 
of K-12 strains in research workers and their families. Moreover, monitoring 
of the laboratory environment has not detected significant numbers of K-12 cells 
and in reconstructed accidental spills, the viable count of K-12 cells were 
found to decrease by 10 million fold in 4 hours if simply left to dry or was 
instantly sterilized if exposed to the mildest germicidal agents. 
[Appendix A — 284] 
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