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work are potential hazards, and no one knows whether any of those hazards 
might ever exist, even if no precautions were taken. We therefore had to 
assume where the hazard might lie, and it has been a general assumption 
that a hazard might be posed if any bacterium or virus carrying a piece 
of foreign DNA were to become established as a stable part of the flora 
of the intestinal tract of any human being or animal. 
By posing that as a potentially dangerous situation we assume that 
once a bacterium or virus carrying a recombinant DNA molecule becomes part 
of the normal flora, it might pose a hazard because the DNA in it might 
become released or might make products that become released and cause in- 
jury to humans, animals or plants. 
So when we ask whether the proposed guidelines are appropriate to 
the hazard, we are really asking if they will guarantee that artificially- 
joined DNA molecules stay in the laboratory and are not disseminated in 
the general population. 
A second level of analysis has gone into the formulation of these 
guidelines. In this analysis an attempt has been made to grade the po- 
tential hazard of a given recombinant DNA. In line with the recommenda- 
tions of the Asilomar meeting, the present guidelines attempt to grade 
a series of protective measures against the potential hazards. The 
argument is that for innocuous recombinants, the usual laboratory 
procedures will suffice, because even if those recombinants got out of 
the laboratory the hazard they pose is no more severe than the hazard 
posed by the microorganism that contains the recombinant DNA. 
I wish to emphasize this point, especially in relation to some of the 
discussion today. It is not conceivable to me that the mere manufacture 
of a recombinant DNA poses a hazard per se. The shuffling and mixing of 
DNA molecules has gone on for eons, and if it were dangerous to add a ran- 
dom piece of DNA to a plasmid or virus, I think we would know that already. 
I think we must focus on those DNAs that have reason to be thought a poten- 
tial hazard, and not on the mere joining of DNA molecules. 
The proposed guidelines become very restrictive as any potential haz- 
ard becomes evident. Taking the hazard that I personally have thought most 
about, the hazard implicit in joining the DNA from a cancer-causing virus 
to a prokaryotic vector, let us see what the guidelines propose in the way 
of safety for the population. 
Reading from page 30 of the guidelines, it states, "P4 plus EK2 or P3 
plus EK3 should be used to isolate DNA recombinants that include all or 
part of the genome of an animal virus." What this means is that my proposed 
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