rr w 
TUFTS UNIVERSITY 
School of Medicine 
Otp«rtMnt oi MobraUr Btetofy 
Mkrobolofy 
January 7, 1982 
Dr. Ullllaa J. Cartland 
Offica of llaco«binant DKA Activlcias 
ITLAD, Bulldlns 31. Rooa 4A52 
National Inatltutaa of Haalth 
Bathaada. Maryland 2020S 
Daar Dr. Cartland: 
I hava a problaa in accepting tha "Unlquancaa Arguaent” prasented 
aa part of tha dlacuaalon of rlska aaaoclatad with racoablnant DMA 
raaaarch (Fadaral Raglatar ^ [233] page S938i, 1981). In essence, 
this says that special precautions would be needed for recoablnant DNA 
work only if "a unique organlsa, never found In Nature, night be constructed 
by reconblnant DNA techniques." (ny cnphasls). 
If 1 understand correctly, the notion Is that a new pathogen that 
night be created by genetic engineers need be treated only as carefully 
as tha pre-axlstlng cognate pathogen. Fair enough. If all of Nature's 
experlnants resulted In failure or In known organlsns, but It does not 
follow that anything Nature has aver produced Is Ipso facto safe. It 
la not even true that tha only dangerous organlsns ever Invented by Nature 
are nodam pathogens. I would not like to sect the bacterial equivalent 
of a dinosaur. 
There nay be Innunerable experlnants that Nature has tried, rarely, 
which resulted In tha death of hunans (or other useful species), sonetlnes 
In Isolated populations, sonetlnes for a United tine, but which haven't 
resulted In nodem pathogens. In nost cases such epldenlcs either pass un- 
noticed or renaln unexplained or occurred before nedlclne was written down. 
Sonetlnes, as In the case of the late ISth century Syphilis before It became 
attenuated, we hava an historical record of the problens that arose. It Is 
a well-established principle that non-adnpted pathogens can be too virulent 
for their hosts' and therefore for their own, survival. Organlsns which became 
extinct In this way can hardly be called safe. 
A second problem Is this. It Is not conceivable that Nature has tried all 
Its experlnants In every possible ecological circumstance. In any case, new 
combinations of environmental parameters are constantly being devised so that 
lyS KUrrteon Av«n«w 
Boston. MsMsebuMtt* eaiii 
Siy e5S-S750 
I 
I641J 
