21 
One, that except for the insertion of genes for a potent toxin, the 
danger of inadvertently creating a pathogen and causing a laboratory infec- 
tion by cloning in K-12 is very much less than the danger of working with 
everyday pathogens that medical bacteriologists work with, and hence the 
dangers within the laboratory are well within the range that has tradition- 
ally been left to the prudence of the investigator risking his own health. 
Secondly, the danger of an epidemic spread of work with clones in K-12, 
and even more in EK2, is virtually nil because of the demonstrated incapacity 
of the organisms to colonize the gut and to transfer their plasmids. This 
was a theoretically sound position two years ago; today it is supported by 
a good deal of evidence. 
Thirdly, and more specifically, the danger of shotgun experiments with 
eukaryotic DNA, even that from humans, really does not seem significant. 
I make this perhaps surprising statement for the following reasons. One, if 
a human tissue contained tumor viruses, any particular clone would have 
about one chance in a million of having picked that up. Secondly, if the 
tumor genes are rare in man, then the chance of picking it up from any 
old human culture are rare. On the other hand, if the tumor virus is so 
widespread in man that we have to worry about picking it up, then it is 
hard to see how very much could be added to its spread by putting it into 
bacteria. Finally, the virus itself is clearly more infectious by many 
orders of magnitude than the DNA of the virus that would have to be released 
from a bacterium in the gut and somehow get into animal cells to prove 
hazardous . 
So, if one had to choose between working with SV40 virus in the tradi- 
tional way, or any other tumor virus in the laboratory today, or working with 
its genome in a bacterium, I would consider the latter much less hazardous 
than the acceptable and necessary procedure of working with dangerous viruses. 
On scientific grounds, then, I would conclude that the original Guide- 
lines have been far too severe, and that the proposed revisions are more 
than justified, and I hope that others will follow as experience mounts 
without casualties and as public anxiety recedes. The public cannot be 
blamed for having a great deal of anxiety in the light of what they have 
read about the subject. 
Now, I think many people must ask how can I justify such an apparently 
extreme view, since the responsible scientists within the field felt con- 
cerned enough to recommend a moratorium at an earlier stage, and many are 
still very deeply concerned today. I believe we have been victims of rather 
gross misunderstanding of the problem, arising with the best of intentions. 
I believe this for the following reasons. First, that the role of genetic 
novelty in the evolutionary spread of organisms has been focused on to the 
exclusion of adequate discussion of the dominating role of natural selec- 
tion in determining what novelty can survive in the competition of nature. 
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