4 
D. Classification of Experiments Using the E. Coli K-12 Containment 
Systems 
The commentators were clearly divided on the classification of 
containment criteria for different kinds of recombinant DNAs. 
Several commentators considered the guidelines to be too 
stringent and rigid. Others viewed the guidelines in certain 
instances as too permissive. And still others endorsed the 
guidelines as sensible and reasonable, affording the public an 
enormous degree of protection. Questions raised by commentators 
are those that have troubled your committee as well. The 
following issues are those to which I would like the committee's 
response. 
Issues for the Committee ’s Consideration 
1. On p. 26 of the guidelines for shotgun experiments with 
eukaryotic DNA recombinants, the committee has recommended 
lower containment levels for DNA from embryonic tissue. 
I concur with the committee's judgment that the likelihood 
of the presence of horizontally transmitted viruses is less 
in embryonic material than in non-embryonic material in the 
same species. But it is clear that careless handling of 
embryonic tissue can cause it to become infected. What is 
the committee's response to a stipulation in the guidelines 
that all such embryonic material be handled under aseptic 
conditions? 
2. On p. 26 of the guidelines there are reduced containment 
levels for foreign DNA from cold-blooded vertebrates. 
I know the effort of the committee to resolve the difficult 
issues in this area. In my view, there is not available to 
us the arguments or evidence that support lower physical and 
biological containment levels for DNA from lower species. 
Unless there are compelling arguments to the contrary, I am 
considering raising the containment levels for cold-blooded 
vertebrates from P2 + EK2 to P3 + EK2 and, further, setting 
the containment levels for embryonic or germ-line DNA from 
cold-blooded vertebrates at P3 + EK1 or P2 + EK2 instead of 
the presently recommended containment level of P2 + EK1. 
What is the committee's response to this suggestion? 
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