I came across this article from 1997 while researching
something for my leukemia group. If you read it in full,
you'll see the relevance to smoking, passive or otherwise.

It also has some interesting relevance to the perennial
aspartame debate and the implications for other food
additives, pollution factors etc, particularly in relation
to the difference in weighting to place on rodent-based
experiments and human experiments.

"ENVIRONMENTAL POLLUTION, PESTICIDES, AND THE PREVENTION OF
CANCER:
MISCONCEPTIONS"
http://www.botanischergarten.ch/debate/AmesMisconc.pdf

Cheers, Alan, T2, Australia.
d&e, metformin 2x500mg