48 
Pi Level (Minimal). At the PI level, physical containment is pro- 
vided by standard microbiological practices. These include antiseptic 
techniques, the daily decontamination of work surfaces, the decontam- 
ination of contaminated liquid and solid wastes, the use of safe pipetting 
procedures, and the observance of appropriate worker hygienic 
procedures. 
A laboratory suitable for experiments involving recombinant DNA 
molecules requiring physical containment at the PI level is shown in 
Figure V-l. Such a laboratory possesses no special engineering design 
features. Special containment equipment is neither required nor 
generally available, and the work is usually conducted on open bench tops. 
The laboratory is not separated from the general traffic patterns of the 
building, and public access may be permitted. 
Figure V-l 
PI Laboratory 
Protective measures equivalent to those described for the PI level 
of physical containment are used to control infectious organisms, such 
as non-pathogenic strains of E. coli, which cause no or minimal hazard 
under ordinary conditions of Handling. This minimal level of contain- 
ment has also been applied to most studies involving tissue cultures 
from man, other primates, and lower mammals. Until the 1950s, 
most organisms that cause disease in man were isolated and studied 
under conditions equivalent to those described for the Pi level. 
P2 Level ( Low ). Physical containment at the P2 level is provided 
by a combination of laboratory practices and containment equipment. 
In addition to those practices required at the PI level, mechanical 
pipetting aids are required; eating, drinking, smoking, and storage 
of food are not permitted in the laboratory; and laboratory garments 
are required. Containment equipment is required to isolate operations 
that produce a considerable aerosol. 
