The True Causes of Cancer
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Environmental activists have long claimed that man-made chemicals are causing rampant cancer rates that could be addressed only by government regulation. Accordingly, lawmakers have passed laws directing government agencies to study environmental causes of cancer, estimate the number of lives allegedly lost, and devise regulations to reduce death rates. However, lawmakers should be aware of some key problems with how this system has worked in practice. First, the claim that chemical pollution is a major cancer cause is wrong. Second, agencies have relied on faulty scientific methods that grossly overestimate potential cancer deaths from chemicals and potential lives saved by regulation. As a result, regulatory policy tends to divert billions of dollars from other life-saving uses or from other efforts to improve quality of life to pay for unproductive regulations.
In their landmark 1981 study of the issue, Richard Doll and Richard Peto set out to determine the causes of preventable cancer in the United States. According to Doll and Peto, pollution accounts for 2 percent of all cancer cases, and geophysical factors account for another 3 percent. They do note that 80 percent to 90 percent of cancers are caused by “environmental factors.” Although activists often trump this figure as evidence that industrial society is causing cancer, Doll and Peto explained that environmental factors are simply factors other than genetics—not pollution alone. Environmental factors include smoking, diet, occupational exposure to chemicals, and geophysical factors. Geophysical factors include naturally occurring radiation, man-made radiation, medical drugs and medical radiation, and pollution. Tobacco use accounts for about 30 percent of all annual cancer deaths. Dietary choices account for 35 percent of annual cancer deaths.
Bruce Ames and Lois Swirsky Gold have come to similar conclusions, noting that smoking causes about a third of all cancers. They underline the importance of diet by pointing out that the quarter of the population eating the fewest fruits and vegetables had double the cancer incidence than those eating the most. Finally, they conclude: “There is no convincing evidence that synthetic chemical pollutants are important as a cause of human cancer.”