NIH Advisory Committee on Recombinant DNA 
Testimony of Bernard D. Davis, M. D. 
Harvard Medical School 
December 15, 1977 
Though I am not here as an official representative of the American Society 
of Microbiologists, my publications on recombinant DNA have led officers of 
that society to recommend me to serve here, and I believe the views that I 
shall present are widely held among microbiologists. 
I am convinced that the alleged dangers from recombinant DNA research 
have been enormously exaggerated, on the basis of scenarios that depend on 
the compounding of many low probabilities. The proposed revisions are therefore 
a step in the right direction. On the basis of what we know today, a year and 
a half after the original guidelines, the following conclusions seem to me 
reasonable. 
1) Except for the insertion of a gene for a potent toxin, the danger of 
creating a pathogen and causing a laboratory infection , by cloning DNA in 
E. coli K12, is very much less than the danger of working with everyday pathogens. 
Hence this danger is well within the range that has been left in the past, without 
substantial danger to society, to the prudence of microbiological investigators. 
2) The danger of epidemic spread from the laboratory, in work with coli 
K12 and even more with its derivative EK2 strain, is virtually nil, because of 
the demonstrated incapacity of the organisms to colonize the gut and to transfer 
their plasmids to more viable organisms. This conclusion was offered a year ago 
on the basis of theoretical considerations; it is now amply supported by 
experimental evidence. 
[Appendix A — 166] 
