biosafety levels

richard richardz at cy-net.net
Tue Jan 7 17:02:56 EST 1997

In article <c=US%a=_%p=Saint_Michael's_%l=PHANTOM-970107193954Z-1447 at phantom.smcvt.edu>, gbauer at smcvt.edu (Glenn Bauer) says:
>        I am trying to find definitions for the biosafety levels (1,2,3, and 4)
>as they pertain to laminar flow hoods.  Can anyone point me in the right
I'm not certain that what I am about to say is a response to your
question, but perhaps the comment will help.

It is my understanding that organisms considered BL-1 are NOT pathogens.
BL-2 covers that broad group of bacteria that most of us routinely
handle in ordinary bench top circumstances.
BL-3, appropriate for the nasties as TB.
I may be incorrect, but I think BL-4 is extensive biosecurity typically
appropriate only for the nasty viruses.

I guess, except for incovenience, it never hurts to operate 1 level
above what is considered appropriate.

With the above in mind, I'm not at all sure what relevance BL-1 or
even BL-2 would have to hoods.

A suitable hood should have HEPA filters for effluent air and have an
airflow pattern that keeps the beasts inside.  Tissue culture hoods
are designed to keep contaminants from getting inside the hood, whereas
a biosafety hood should be designed to contain the pathogens.

Therefore, you can't assume that a good tissue culture hood would necessarily 
be a good biosafety hood. 

I hope someone more knowledgeable than I am jumps into this exchange.
I would like to hear more authoritative responses.

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