APPENDIX E 
In the experiments discussed in the guidelines the host cells are 
generally single living cells, either microorganisms such as bacteria, or 
animal or plant cells grown as single cells In tissue culture. 
General Principles . The guidelines start with a statement of general 
principles and these are consistent with the general conclusions published 
in the report of the International Conference on Recombinant DNA at Asiiomar, 
2 / 
California, in February of 1975 . (1) The first principle is that there are 
certain experiments which, in the I ight of currently available information, 
may be judged to present potential hazards of so serious a nature, that they 
should not be attempted at this time. (2) A large group of feasible experi- 
ments appear to pose lesser or no potential hazard, and can therefore be 
performed provided that the information to be obtained, or the practical 
benefits anticipated, cannot be obtained by conventional methods, and provided 
that appropriate safeguards for containment of potentially hazardous organisms 
are incorporated into the design and execution of the experiment. (3) That 
the more serious the nature of any possible hazardous event, the more stringent 
should be the safeguards against escape of the potentially hazardous agents. 
The safeguards should be at least as stringent as those generally used to handle 
the most hazardous parent of the recombinant. Since the estimation of potential 
hazards is conjectural and speculative, the levels of containment required for 
potentially hazardous organisms should be set high initially, and modified only 
when there is substantial relevant Information to advise such modifications. 
(4) That the guidelines are to be reviewed at least annually in order to account 
for new information. 
Containment Methods : Three approaches to the problem of containing 
potentially hazardous organisms form the basis of the safeguards recommended by 
the guidelines. Each of the three may be viewed as setting up barriers to the 
Appendix E — 4 
