3 
Issuance of and compliance with the Guidelines decreases the chance 
that NIH-assisted recombinant DNA research will have a negative effect 
on the environment. To the extent that the Guidelines are used as a 
model of safe research practice for recombinant DNA research that 
is not NIH-assisted, the risk of negative environmental effect will be 
further reduced. Confidence in the Guidelines is derived mainly from 
a consensus of the judgments of knowledgeable scientists who have been 
consulted. There is also an experimential base that is relevant. This 
is the fact that laboratory scientists have worked for about 100 years 
with various agents identified as capable of causing disease without 
any known adverse impact on the environment. The confidence of the 
scientists who have prepared and critically reviewed these guidelines 
is based on two premises. First, it is believed that the containment 
measures specified in the Guidelines make the escape of potentially 
harmful recombinant organisms into the environment highly improb- 
able. Second, it is believed that even if an experiment performed in 
accordance with the Guidelines does result in accidental release of 
recombinant organisms, adverse effects will either not occur or not 
be serious. 
In the absence of an adequate base of data derived from either 
experiments or experience, it must be recognized that future events 
may not conform to these judgments. There is some statistical 
probability that recombinant organisms will find their way into the 
environment either from experiments under NIH auspices or from 
the activities of others. It is not difficult to construct hypothetical 
scenarios in which injury could result. Although the possibility of 
significant environmental consequences is speculative, the chance of 
an event that could cause severe injury, however low the probability, 
must be treated as a possible adverse impact on the environment. 
The NIH Guidelines, while designed to ensure the safety of NIH- 
supported researchers, the general public, and the environment, also 
serve as a model for other laboratories throughout the world, thereby 
promoting environmental protection not otherwise achievable through 
the Federal Government. And it should be emphasized that the exper- 
iments which are the subject of the Guidelines are expected to lead 
ultimately to an increase of knowledge and the advancement of medicine 
and other sciences in ways that should profoundly benefit mankind. 
The Director of NIH believes that the NEPA review will focus 
attention on the important issues involved, in the interest of gaining 
the understanding and views of the broadest possible segment of the 
American people. In issuing the Guidelines, the NIH Director pointed 
out that they will be subject to continuous review and modification in 
the light of changing circumstances. Constructive modification could 
result from information received during the NEPA process. 
