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C. Biological Containment Requirements 
Some readers of the Draft EIS noted that the term biological contain- 
ment was not used in the statement, while it has been used extensively 
in the Guidelines and in public discussion of recombinant DNA issues. 
The term was omitted from the Draft EIS on grounds that it might be 
confusing to lay readers. Confusion can arise because "biological 
containment" does not, in fact, contain the organisms in the sense 
that their dispersion from the laboratory is controlled. Rather, the 
term is used to describe organisms that, were they to escape the 
laboratory, would have only a slight probability of growing in natural 
environments. The concept of biological containment is discussed in 
detail in Sections II and III of the Guidelines. 
In addition to explaining the concept of biological containment, this 
section describes the properties of the E. coli K-12 host-vector systems. 
(See also Section VI-C-3-b.) 
D. Combination of Physical and Biological Containment 
in Practice 
Within the EIS the concept of biological containment is now explicitly 
stated. It is also implied in the framework for assessment for danger 
given in Section V-D. Extensive material has been added to this section 
explaining the Guidelines' standards as applied to particular types of 
experiment and presenting examples of containment systems. Items 
(4), (5), (7), and (8) in the list beginning "The criteria for assessing 
the possibility for danger are:" concern the ability of the vector or the 
host cell to survive in natural environments or to transmit recombined 
genes to other organisms that might be encountered in natural environ- 
ments. Since the possibility for danger will increase with the degree 
to which these items in the list increase (as indicated in this Section), 
the use of host-vector systems chosen or designed to minimize these 
possibilities (such as EK1, EK2, EK3, or defective polyoma and SV40 
viruses) decreases the potential for hazard in a given experiment. 
An explanation for the requirement of higher containment levels 
for experiments involving recombinant DNA from higher organisms 
(e.g., primates) appears in this section under the subhead "Examples 
of Containment Systems" [26]. 
For the convenience of readers for whom the Guidelines themselves 
are too technical, a review of these concepts and of the Guidelines 
themselves can be found in an added Appendix E to the EIS. 
