79 
The summary of the Falmouth Workshop on Risk Assessment (see 
Appendix M) states: "The mode of spread of enteric bacteria (viz., 
by the fecal -oral route) virtually eliminates the epidemic potential of 
any strain in areas where the water supplies are protected from con- 
tamination with raw sewage" (8). Further documentation of these points 
is found in the quotation on the following page by microbiologist Roy 
Curtiss (7). 
There remains the question whether the insertion of a foreign DNA 
fragment into K-12 will significantly alter the properties of the latter 
with regard to survival and multiplication, or the ability of the plasmid 
and bacteriophage vectors to be spread. The improbability of thereby 
converting K-12 to a pathogen has already been discussed. Changes in 
ability to survive and multiply would be expected to involve not only the 
changes in the K-12 itself, or the plasmid or bacteriophage, but the 
nature of the environment in which it finds itself. 
These questions are discussed in Section IV-C-2 of this EIS from a 
general point of view. Recently, additional data pertaining to the K-12 
systems have been obtained. Those data relevant to lambda, the 
bacteriophage vector, indicate that insertion of foreign DNA fragments 
does not result in any increase in the efficiency of bacteriophage 
reproduction (14). Additional, more detailed information is given in 
reference 7. 
Defective K-12 Systems . Theoretically, the most desirable bacte- 
rial recipient of recombinant DNA would be a species uniquely adapted 
to carefully controlled laboratory environments and unable to survive 
or transmit DNA to other organisms in any natural environment. This 
means that the bacterium should be unable to survive in normal ecolog- 
ical niches. It should be unable to establish itself as a long-lived and 
multiplying resident in or on living things, or in soil or water. In 
addition, these properties should not be significantly altered by 
insertion into the bacterium of recombined DNA. The organism should 
also, of course, lend itself to manipulation for successful execution 
of the proposed experiments. 
No bacterium meeting all these requirements is known. Further- 
more, it is possible that no such bacterium exists in nature. Available 
bacterial systems must be evaluated for relative safety and utility, 
depending on the extent to which they approach the ideal criteria. The 
foregoing summary of knowledge concerning K-12 and its known 
plasmids and bacteriophages indicates that these systems measure up 
very well when compared with the ideal criteria, and can therefore 
be recommended for use in certain recombinant DNA experiments. The 
Guidelines permit the use of such systems --EK1 --for those experiments 
whose potential for hazard is considered to be nil, low, or minimal. 
