134 
The NIH Guidelines require that waste water from a P4 facility 
be collected and sterilized before being discharged to the sanitary 
sewer. This is a secondary precaution to prevent the release of a 
contaminant to the environment in the event of an accidental escape 
of microorganisms from the primary barrier system (i.e., class 
III biological safety cabinet). For experiments of less hazard -potential 
(i.e.. Pi, P2, and P3), the NIH Guidelines require decontamination 
of all contaminated liquid and solid materials before disposal. Secondary 
sterilization, however, is not required for these materials. In the 
review by Wedum (10), no evidence was found that this additional 
precaution is needed. 
2. Impact on the Environmental Spread of Possibly Hazardous Agents 
There is no supporting epidemiological experience which suggests 
that the research conducted at Fort Detrick was hazardous to the 
public. Although there was a total of 42 3 laboratory-acquired infections 
over the 2 5 years of Fort Detrick's operations, during which a variety 
of primary containment conditions were employed (Pi to P4), no member 
of the general public was ever infected as a result of research at Fort 
Detrick (12). 
Experience with highly infectious microorganisms does not indicate 
a need to provide more stringent facility safeguards for the P3 and P4 
levels than those required by the NIH Guidelines. Wedum (10) stated: 
"As far as biohazard outside the building is concerned, most secondary 
barriers are more for reasons of public relations than for anything 
else, except for pilot plants or other large-volume production, experi- 
mental aerosols, use of tick or insect vectors, and agents capable of 
spread to animal or plant food supply. This view assumes that known 
infectious liquids, solids, animals, and animal wastes are decontam- 
inated before disposal, as has long been standard practice in all 
microbiological laboratories. " 
3. Cost Impact 
Several commentators also requested specific cost estimates for 
preparing facilities to accommodate recombinant DNA research [13,20]. 
The text has been expanded to provide such information. 
4. Secondary Impacts 
No comments were addressed to this Section. 
