one or more of the segments may be a 
synthetic equivalent. 
I-E-3. Those that consist entirely of 
DNA from a prokaryotic host, includ- 
ing its Indigenous plasmids or viruses, 
when propagated only in that host (or 
closely related strain of the same spe- 
cies! or when transferred to another 
host by well-established physiological 
means: also those that consist entirely 
of DNA from a eukaryotic host, in- 
cluding its chloroplasts. mitochondria, 
or plasmids (but excluding viruses), 
when propagated only in that host (or 
a closely related strain of the same 
species). 
I-E-4. Certain specified recombinant 
DNA molecules that consist entirely of 
DNA segments from different species 
that exchange DNA by known physio- 
logical processes, though one or more 
of the segments may be a synthetic 
equivalent. A list of such exchangers 
will be prepared and periodically re- 
vised by the Director, NIH, with 
advice of the Recombinant DNA Advi- 
sory Committee, after appropriate 
notice and opportunity for public com- 
ment. (See Section IV-E-l-b-< lWd).) 
Certain classes are exempt as of publi- 
cation of these Revised Guidelines. 
The list is in Appendix A. An updated 
list may be obtained from the Office 
of Recombinant DNA Activities, Na- 
tional Institutes of Health, Bethesda. 
Maryland 20014. 
I-E-5. Other classes of recombinant 
DNA molecules, if the Director. NIH. 
with advice of the Recombinant DNA 
Advisory Committee, after appropriate 
notice and opportunity for public com- 
ment. finds that they do not present a 
significant risk to health or the envi- 
ronment. (See Section IV-E-l-b-O)- 
(d).) 
I-P. General Definition*. See Sec- 
tion IV-C. 
II. Containment 
Effective biological safety programs 
have been operative in a variety of lab- 
oratories for many years. Considerable 
information therefore already exists 
for the design of physical containment 
facilities and the selection of labora- 
tory procedures applicable to organ- 
isms carrying recombinant DNAs. [6- 
19] The existing programs rely upon 
mechanisms that, for convenience, can 
be divided into two categories: (i) A set 
of standard practices that are general- 
ly used In microbiological laboratories, 
and ( il ) special procedures, equipment, 
and laboratory Installations that pro- 
vide physical barriers which are ap- 
plied in varying degrees according to 
the estimated biohazard. 
Experiments on recombinant DNAs, 
by their very nature, lend themselves 
to a third containment mechanism— 
namely, the application of highly spe- 
cific biological barriers. In fact, natu- 
ral barriers do exist which limit either 
NOTICES 
(i) the infectivity of a vector, or vehi- 
cle, (plasmid or virus) for specific 
hosts or (ii) its dissemination and sur- 
vival in the environment. The vectors 
that provide the means for replication 
of the recombinant DNAs and/or the 
host cells In which they replicate can 
be genetically designed to decrease by 
many orders of magnitude the prob- 
ability of dissemination of recombin- 
ant DNAs outside the laboratory. 
As these three means of contain- 
ment are complementary, different 
levels of containment appropriate for 
experiments with different recombin- 
ants can be established by applying 
various combinations of the physical 
and biological barriers along with a 
constant use of the standard practices. 
We consider these categories of con- 
tainment separately here in order that 
such combinations can be conveniently 
expressed in the Guidelines. 
In constructing these Guidelines, it 
was necessary to define boundary con- 
ditions for the different levels of phys- 
ical and biological containment and 
for the classes of experiments to 
which they apply. We recognize that 
these definitions do not take into ac- 
count all existing and anticipated in- 
formation on special procedures that 
will allow particular experiments to be 
carried out under different conditions 
than indicated here without affecting 
risk. Indeed, we urge that individual 
investigators devise simple and more 
effective containment procedures and 
that investigators and institutional 
biosafety committees recommend 
changes in the Guidelines to permit 
their use. 
II-A. Standard Practices and Train- 
ing. The first principle of containment 
is a strict adherence to good microbio- 
logical practices. [6-15] Consequently, 
all personnel directly or Indirectly in- 
volved in experiments on recombinant 
DNAs must receive adequate instruc- 
tion. (see Sections IV-D-l-g, IV-D-5-d 
and IV-D-8-b.). This shall as a mini- 
mum include instructions in aseptic 
techniques and in the biology of the 
organisms used in the experiments, so 
that the potential biohazards can be 
understood and appreciated. 
Any research group working with 
agents with a known or potential bio- 
hazard shall have an emergency plan 
which describes the procedures to be 
followed if an accident contaminates 
personnel or the environment. The 
principal Investigator must ensure 
that everyone in the laboratory is fa- 
miliar with both the potential hazards 
of the work and the emergency plan. 
(See Sections IV-D-5-e and IV-D-3-d.) 
If a research group is working with a 
known pathogen where there is an ef- 
fective vaccine it should be made avail- 
able to all workers. Where serological 
monitoring is clearly appropriate it 
60109 
shall be provided. (See Sections IV-D- 
1-h and IV-D-8-c.) 
II-B. Physical Containment Levels. 
The objective of physical containment 
is to confine organisms containing re- 
combinant DNA molecules, and thus 
to reduce the potential for exposure of 
the laboratory worker, persons outside 
of the laboratory, and the environ- 
ment to organisms containing recom- 
binant DNA molecules. Physical con- 
tainment is achieved through the use 
of laboratory practices, containment 
equipment, and special laboratory 
design. Emphasis is placed on primary 
means of physical containment which 
are provided by laboratory practices 
and containment equipment. Special 
laboratory design provides a secondary 
means of protection against the acci- 
dental release of organisms outside 
the laboratory or to the environment. 
Special laboratory design is used pri- 
marily in facilities in which experi- 
ments of moderate to high potential 
hazard are performed. 
Combinations of laboratory prac- 
tices, containment equipment, and spe- 
cial laboratory design can be made to 
achieve different levels of physical 
containment. Four levels of physical 
containment, which are designated as 
PI, P2. P3. and P4, are described. It 
should be emphasized that the de- 
scriptions and assignments of physical 
containment detailed below are based 
on existing approaches to containment 
of pathogenic organisms. For example, 
the "Classification of Etiologic Agents 
on the Basis of Hazard," [7] prepared 
by the Center for Disease Control, de- 
scribes four general levels which 
roughly correspond to our descriptions 
for PI. P2. P3, and P4; and the Nation- 
al Cancer Institute describes three 
levels for research on oncogenic vir- 
uses which roughly correspond to our 
P2. P3. and P4 levels. [8] 
It is recognized that several differ- 
ent combinations of laboratory prac- 
tices. containment equipment, and spe- 
cial laboratory design may be appro- 
priate for containment of specific re- 
search activities. The Guidelines, 
therefore, allow alternative selections 
of primary containment equipment 
within facilities that have been de- 
signed to provide P3 and P4 levels of 
physical containment. The selection of 
alternative methods of primary con- 
tainment is dependent, however, on 
the level of biological containment 
provided by the host-vector system 
used in the experiment. Consideration 
will also be given by the Director. 
NIH. with the advice of the Recombin- 
ant DNA Advisory Committee to other 
combinations which achieve an equiva- 
lent level of containment. (See Section 
IV-E-l-b-(2Mb).) Additional material 
on physical containment for plant 
host-vector systems is found in Sec- 
tions III-C-3 and III-C-4. 
FEDERAL REGISTER. VOC 43, NO. 247 — FRIDAY, DECEMBER 22. 1778 
