The study of how substances alter gene expression is part of the field of epigenetics. Some chemical exposures appear to turn on and turn off genes in ways that disregulate cell growth and predispose for cancer. From this perspective, our genes are less the command-and-control masters of our cells and more like the keys of piano, with the environment as the hands of the pianist.

Living Downstream: An Ecologist's Personal Investigation of Cancer and the Environment (ed. Da Capo Press, 2010) - ISBN: 9780306818691