STANFORD UNIVERSITY
MEDICAL CENTER 3(
PALO ALTO, CALIFORNIA /

DEPARTMENT OF GENETICS

School of Medicine

Goshua Lederberg

_
bne>:

March 19, 1969

RN

Dear Dr. Wuréser-

Thank you for the material.

I have no information on mutagenicity of DDT. I would caution
you on loose talk and misinterpretation, like the enclosed, which
confuses selective effects (favoring better adapted genotypes) with
mutation-induction.

In fact, our general me thodology in this area is very bad. Before
long every compound is going to flunk the leucocyte/chromosome
breakage test, which may discredit the whole inquiry. By the same
token we might have to inculpate coffee, and we would if we did not
have a better understanding now of the mechanism of action of caffeine
(an inhibitor of some enzymes of DNA repair) that rule out a simple
extrapolation from high doses- in laboratory experiments to low ones in
human exposure.

A propos DDT, one of my deepest concerns would be its ecological
impact, i.e., the selection for more resistant species of marine
algae xhkanxany which could have serious adverse effects long before
we actually had to worry about the termination of photosynthesis.

Finally, I would be disappointed at a ruling that peremptorily
forbade DDT. It ought to be licensed and regulated, perhaps even
taxed to balance the merits with the costs. I am afraid this kind
of blanket determination may set a very poor precedent for making
a flexible responsef to other social irritations where your and my
own preferences maght be quite on the other side. the legal approach
to marijuana is a case in point.

PS: Is the whole subject of Porcinkey

DDT effects going to be reopened
by differential effects of the
o- and p- isomers?