26 
MINUTES OF MEETING - June 5-6 
5 agents. She noted that a proposed revision of the CDC classification 
of etiological agents will soon be issued. Dr. Bems said he favored 
waiting for the CDC revised classification to appear before consider- 
ing further modifications in Section I-D-l. He felt that the revised 
classification, because of the number of individuals participating in 
the review, would be better than any RAC could construct. He thought 
the RAC review process afforded by the Guidelines was adequate until 
the revised CDC classification became available. Dr. Goldstein ques- 
tioned Dr. Dowdle of CDC on the status of the CDC revision. Dr . Dowdle 
said reviewers' comments had been received and that substantial modi- 
fications of format, as well as classification of sane organisms 
would be incorporated into a revised document, and that a draft will 
be circulated to the RAC. 
Dr. Gottesman said she was inclined to maintain the status quo. She 
said that there had been no requests for permission to do recombinant 
DNA experiments employing CDC Class 4 or 5 organisms. E^r. Setlow 
said she sensed a concensus for maintaining the status quo and 
suggested Dr. Nightingale begin discussion of the next item. 
Et. Nightingale noted that Section I-D-2 prohibits "deliberate 
formation of recombinant ENAs containing genes for the biosynthesis 
of toxins potent for vertebrates (2A) (e.g., botulinum or diphteria 
toxins; venoms from insects, snakes, etc.)" She said an ad hoc 
group chaired by Dr. Maas was attempting to define what is a potent 
toxin. E*r. Maas said he had composed a table (tab 895) outlining the 
lethal dose of various bacterial toxins. He said the table has limi- 
tations in that (1) the amount of information available is limited; 
(2) lethality is measured for experimental animals, and humans may 
react quite differently; and (3) deleterious effects other than 
lethality have not been considered. He suggested that perhaps only 
the cloning of botulinum and tetanus toxins should be prohibited. 
Cloning of other toxins could be considered on an individual basis. 
Dr. Campbell expressed concern that human sensitivity to a toxin may 
differ significantly from that of animal test systems. Dr. Ahmed 
said that enough uncertainty existed in the data to render consider- 
ation of the proposal very difficult. Dr. Young suggested that 
potent toxins might be dealt with generically by removing them from 
the prohibitions and setting containment at P4. Dr. Levine said 
botulinum toxin is in a class by itself; extraordinarily small quan- 
tities can kill by the oral route. He said tetanus toxin can also 
kill in quantities too small to elicit an immune response, but must 
be administered parenterally. 
Dr. Nightingale pointed out that plant toxins, some of which are 
very potent, are not covered by the prohibitions. She suggested 
that this type of toxin be reviewed by an appropriate group. 
Dr. Young said he felt the bacterial toxins should be examined 
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