98 
which is a policy issue that I would like to discuss later. But I thought 
that he identified the extent to which in the natural environment there 
was a tremendous capability of the body to resist invasion of that which 
was found in the natural environment. He has indicated the extent to which 
he has been engaged in the research which was not serious or dangerous. I 
would sort of like him to comment on the extent to which he is concerned 
about creating an organism that is not found in the natural environment and 
whether or not you can place the same degree of confidence in the body's 
ability to react in a manner which is not adversely affected by that or- 
ganism which is not normally found in the environment. 
He has identified the extent to which the safety precautions had been 
completely adequate where you were dealing with an organism that was found 
in the environment. What we are talking about is creating an organism that 
is not normally found in the environment, and what the degree of threat that 
that represents, and how much of a safeguard you should take against that. 
DR. FREDRICKSON: Dr. Petersdorf? 
DR. PETERSDORF: Well, I would like to share the answer with Dr. 
Melnick, who is a distinguished virologist, and I think in the virus field 
the answer may be somewhat different than in the bacterial field. 
Dr. Curtiss certainly pointed out that some enteropathogens can be 
introduced into that parent bacteria which might potentially make them 
pathogenic. Now, there are two things I would say about that. One is 
where you know that, you don't do that experiment in terms of the — or 
you try not to do that experiment because that is one of the things which 
will be ecologically, I think, unsafe and potentially hazardous. 
Furthermore, even when working with enteropathic organisms, such as 
Salmonella and Pseudomonas and some of the other ones, the incidence of 
infections in the laboratory, short of drinking a culture flask of that 
stuff, which very few of us would enjoy, is very small — in other words, the 
physical precautions within the knowledge that we have should take care of 
this matter. 
Now, what we don't know, and where I agree that Dr. Berg has a point, 
we may be creating something somewhere along the line, a potential patho- 
genicity of which we do not know, and the response of the host we do not 
know. I think this is probably the biggest danger. 
I have been impressed listening to the molecular biology of this 
meeting, that the E. coli , as long as you use that as a host, has been 
attenuated, so I am not at all sure that you are ever going to do a hell 
of a lot for that particular E_j_ coli to make it hazardous for man. I can't 
comment on what it might do to other organisms in the environment because 
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