10 
to specify the nature of the biological containment under host-vector 
headings such as those given below for Escherichia coli K-12 (pp. 13-25). 
D. Publication - The committee strongly recommends that all 
publications dealing with recombinant DNA work include a description of 
the physical and biological containment procedures practiced, to aid and 
forewarn others who might consider repeating the work. 
Ill . Experimental Guidelines 
A general rule that, though obvious, deserves statement is that the 
level of containment required for any experiment on DNA recombinants shall 
never be less than that required for the most hazardous component used to 
construct and clone the recombinant DNA (i.e., vector, host, and inserted 
DNA). In most cases the level of containment will be greater, particularly 
when the recombinant DNA is formed from species that ordinarily do not 
exchange genetic information. Handling the purified DNA will generally 
require less stringent precautions than will propagating the DNA. However, 
the DNA itself should be handled at least as carefully as one would handle 
the most dangerous of the DNAs used to make it. 
The above rule by itself effectively precludes certain experiments-- 
namely, those in which one of the components is in Class 5 of the 
"Classification of Etiologic Agents on the Basis of Hazard" (5), as these 
are excluded from the United States by law and USDA administrative policy. 
There are additional experiments which may engender such serious biohazards 
that they should not be performed at this time. These are considered prior 
to presentation of the containment guidelines for permissible experiments. 
[811 
