Ames, B. N., and Gold, L. S., Environmental pollution, pesticides, and the prevention of cancer: Misconceptions. FASEB J. 11: 1041-1052 (1997).
The major causes of cancer are: 1) Smoking: About a third of U.S. cancer (90% of lung cancer); 2) Dietary imbalances, e.g., lack of dietary fruits & vegetables: The quarter of the population eating the least fruits & vegetables has double the cancer rate for most types of cancer compared to the quarter eating the most; 3) Chronic infections: mostly in developing countries; 4) Hormonal factors: primarily influenced by life style. There is no epidemic of cancer, except for lung cancer due to smoking. Cancer mortality rates have declined 16% since 1950 (excluding lung cancer). Regulatory policy that focuses on traces of synthetic chemicals is based on misconceptions about animal cancer tests. Recent research indicates that rodent carcinogens are not rare. Half of all chemicals tested in standard high dose animal cancer tests, whether occurring naturally or produced synthetically, are "carcinogens"; there are high-dose effects in rodent cancer tests that are not relevant to low-dose human exposures and which contribute to the high proportion of chemicals that test positive; The focus of regulatory policy is on synthetic chemicals, although 99.9% of the chemicals humans ingest are natural. Over 1000 chemicals have been described in coffee: 28 have been tested and 19 are rodent carcinogens. Plants in the human diet contain thousands of natural pesticides which protect them from insects and other predators: 63 have been tested and 35 are rodent carcinogens.
There is no convincing evidence that synthetic chemical pollutants are important for human cancer. Regulations that try to eliminate minuscule levels of synthetic chemicals are enormously expensive: EPA has estimated that environmental regulations cost society $140 billion/year. It has been estimated that the median toxic control program costs 146 times more per life year saved than the median medical intervention. Attempting to reduce tiny hypothetical risks also has costs, e.g., if reducing synthetic pesticides makes fruits and vegetables more expensive, thereby decreasing consumption, then cancer will be increased, particularly for the poor. Prevention of cancer will come from knowledge obtained from biomedical research, education of the public, and from lifestyle changes by individuals. A re-examination of priorities in cancer prevention, both public and private, seems called for.
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Last updated: August 1, 2001