Environmental and occupational causes of cancer: a call to act on what we know.

The discussion of the scientific evidence linking cancer to environmental and occupational exposures has been an area of contention for atleast the past three decades, since the assertion in 1977 by Higginson and Muir that 80% of all cancers were due to environmental exposures. Over the past three decades, there have been additional efforts to estimate the proportion of cancer due to these involuntary exposures, including the 1981 monograph by Doll and Peto and the more recent reports by the Harvard Center for Cancer Prevention. In this paper, we review the evidence that Doll and Peto and other authors have summarized, provide an alternative interpretation of the evidence, and caution against the very idea of attributing specific fractions or proportions of cancer to particular factors. We also review the scientific evidence, particularly epidemiologic evidence, regarding the contribution of environmental and occupational exposures to the overall cancer burden in the US. We conclude with a call for action to prevent exposures to environmental and occupational carcinogens.