Memo from To: Alex Fa Fecoet
_—_———e

JOSHUA LEDERBERG Al
AUB 6 1973

7 K -:
<t?Z ~- Hon-absorbable polymers

~
Have you pondred how difficult it may be
, to anticipate the eventual selection of micro.
bial flora that will degrade the polymer car-
rier, or modify it, or release the attached

“gustaphore" or chromophore or what have you?

This is likely to complicate the toxico-

ALZA

logy more than the primary efficacy; and with

 

Wey oyymers in widespresd, non-vital uses, there
will be special concenns about allergentcity.
If se given complex becomes widely used,
the spread of adapted bacteria from person to
person will eccelerate the selection.
Ager might be exemined as a possible coun-
ter example to my concern (or as e® carrier al-

ready widely used and relied upon).

Cyclamate was originally believed to be
nonebsorbable. The absorption of cyclohexyl-
amine is almost surely a byproduct of gut
flora that do become adepted to this ‘nutri-
ent’, (Simpler modifications of cyclamate

might slready solve the problem!)
Good Tuck,

ssO® JOSHUA LEDERBERG

epartment of Genetics
School of Medicine
Stanford University
Stanford, California 94305