71 
MS. PFUND: Yes. 
DR. FREDRICKSON: I would like to have Dr. Barkley just mention his 
view of that . 
DR. BARKLEY: Well, this obviously has been a point of consideration 
for the last four years. At a P3 laboratory all work with potentially 
hazardous materials must be confined to biological safety cabinets. Those 
cabinets exhaust air, and they are designed to prevent escape of organisms 
into the environment if the laboratory worker mi s funct ions . The exhaust air 
from those cabinets must be treated before it is discharged. 
The air that we are talking about exhausting out of the laboratory 
building is the air that the laboratory worker is breathing 8 hours, 10 
hours, 24 hours a day. It is true that there is a likelihood that that 
air can become contaminated in the event of some gross spill or accident. 
It was felt, therefore, that the appropriate way to see that the air that 
could be accidentally contaminated would not be widely distributed within 
the confined space of the laboratory facility would be to discharge it out- 
side, where it could be reduced in number by the sun, environmental stresses, 
dilution. But this is only an accidental situation that that air is likely 
to become contaminated. We drew very heavily on the experience over the last 
100 years with human pathogens, many of which had the potential of causing 
epidemics, and the situation is that we have not been able to find anywhere 
where the exhaust air from any facility handling highly pathogenic organisms, 
where these things were commonly handled on the open bench, had caused any 
insult to a community by their discharge outside. So the method of taking 
the general ventilation air which is breathed by the laboratory worker and 
discharging it outdoors seems to be an appropriate approach for dealing 
with agents at a P3 level. 
When we are concerned that in an accidental situation that release 
must be prevented, the agent at that hazard level would be confined to a 
P4 laboratory, where the general ventilation of air is indeed treated. 
MR. DACH: I guess I would like to see clarified whether the risk 
is as minimal as you say, and also just as a point of clarification, you 
were talking about a monetary expense as a rationale for why it is not 
required . 
DR. BARKLEY: It is not a monetary expense. I think what we are trying 
to do is see that the safeguards that are employed are appropriate to the 
purpose that they have. I am very much concerned about the use of funds to 
build what I call monuments for biohazards control that really don't impact 
on the problem. I would much prefer if it is true that it is going to be 
costly to put in filters on exhaust air in P2 or P3 facilities, I think it 
would be much more cost-effective to use those funds to buy more hoods, to 
jeffect more training programs, to provide more space so that crowding is 
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