59 
DR. BARKLEY: And some of the experiments assigned to their level 3 are 
experiments which we only allow at our level P4 , or prohibit altogether. 
DR. AHMED: That makes a li 
It depends on 
how 
you 
inter 
DR. BARKLEY: 
You 
are 
absol 
one element of 
the 
Guidel ine 
every level. 
DR. FREDRICKSON: 
Mr. 
Hutt? 
ttle problem about harmonizing thing 
pret the various containment levels. 
utely correct. Physical containment 
s, and harmonization needs to be ach 
s, doesn 
is 
ieved 
't 
MR. HUTT: Dr. Barkley, it is my recollection that when the Guidelines 
were first proposed, roughly two years ago, there were requirements for 
good microbiological practices, but nothing terribly specific in it. Appar- 
ently as a result of the advice of this Advisory Committee back when it con- 
sidered this matter, I guess in February of 1976, there were some detailed 
provisions put in, I believe, in an appendix, Appendix D, dealing with good 
microbiological practices. Those do not appear in the proposed new redraft, 
and I would like the reasons for the deletion of those if indeed there is 
to be a deletion. 
DR. BARKLEY: You are absolutely correct. At the Advisory Committee 
meeting that you referred to, there was felt a need for more emphasis on 
personnel practices, and that emphasis was placed in the final standard. 
The Appendix D was then a supplement document which was intended to provide 
more how-do-you-do-it information, of how do you implement the principles 
in the standards. They were not included in the current proposed revision 
because they were not intended to be specific requirements. They were more 
a reference document on certain approaches that would be consistent with 
those principles. That is the main reason that it wasn't included, because 
it wasn't a particular requirement. 
I have been asked, however, to revise that Appendix D to include a 
preface which would indicate its true purpose and function, and to see that 
that Appendix, if it is the desire of this Committee, be again added back to 
the revised Guidelines, the proposed Guidelines. 
DR. FREDRICKSON: Dr. DeRoos? 
DR. DE ROOS : I would just like to express the preference that it be 
added back in the full statement. 
DR. FREDRICKSON: Others have in their letters too, and I quite concur. 
Mr. Beaty. 
MR: BEATY: I have a specific question regarding Class II biological 
safety cabinets. There were a large number on the market before the 
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