II. THE OBJECTIVES AND STATUS OF THE DNA 
RECOMBINANT MOLECULE GUIDELINES 
A. Introduction 
At the beginning of the controversy over the use of the DNA recom- 
binant molecule technique, the primary issue was one of the potential 
for possible hazard to the public health and safety. With this issue 
as a focus of attention, the scientific community identified a series of 
requirements for conducting approved research, which they believed 
to be suitable for assuring the continuation of research with a minimum 
of potential for harm. Basically, these requirements are divided into 
two forms of containment: physical barriers utilizing the best tech- 
nologies for safe handling such as hoods for safeguarding the dis- 
semination of aerosols, high temperature autoclaves for disinfecting, 
filters, negative pressure and similar laboratory architectural and 
equipment requirements; and the use of a unique biological method 
of deliberately selecting for experimental use mutant organisms which 
lack the capability to survive in nature because of unique growth 
requirements available only in the laboratory medium in which they 
are grown. These requirements have now been promulgated by the 
National Institutes of Health as guidelines to be followed for all DNA 
recombinant molecule research supported by Federal funds* 
B. Physical Containment 
Dr. Barkley 
Emmett Barkley, Director, Office of Research Safety, National 
Cancer Institute addressed the development and utilization of physical 
containment standards which are being prescribed for all federally 
funded DNA recombinant molecdle research. As he pointed out in 
his introductory comments, the objective of physical containment 
standards is to confine to the laboratory the research organisms 
containing recombinant molecules. Four levels of physical containment 
are specified within the DNA recombinant molecule Federal guide- 
lines. These levels are code designated Pi, P2, P3 and P4. The least 
potentially hazardous experiments are permitted under Pi conditions 
and the experiments about which there is the least information and 
which are estimated to have the potential for a relatively high degree 
of hazard are assigned to the P4 type of laboratory. 
The Pi level of containment is fundamentally the use of good micro- 
biological practices. P2 provides for a combination of good microbio- 
logical practice plus the use of certain types of containment equip- 
ment and the specification of good sanitation procedures. At the 
P3 level more stringent microbiological laboratory practices are 
specified, entry and exit procedures are imposed to minimize trans- 
port out of the laboratory of possible contaminating substances, 
and facility safeguards such as double-doored entrances, controlled 
( 21 ) 
[Appendix B — 70] 
