ENVIRONMENTAL-POLLUTION, PESTICIDES, AND THE PREVENTION OF CANCER - MISCONCEPTIONS

The major causes of cancer are: 1) smoking, which accounts for about a third of U.S. cancer and 90% of lung cancer; 2) dietary imbalances: l ack of sufficient amounts of dietary fruits and vegetables. The quarte r of the population eating the fewest fruits and vegetables has double the cancer rate for most types of cancer than the quarter eating the most; 3) chronic infections, mostly in developing countries; and 4) ho rmonal factors, influenced primarily by lifestyle. There is no cancer epidemic except for cancer of the lung due to smoking, Cancer mortalit y rates have declined by 16% since 1950 (excluding lung cancer). Regul atory policy that focuses on traces of synthetic chemicals is based on misconceptions about animal cancer tests. Recent research indicates t hat rodent carcinogens are not rare. Half of all chemicals tested in s tandard high-dose animal cancer tests, whether occurring naturally or produced synthetically, are ''carcinogens''; there are high-dose effec ts in rodent cancer tests that are not relevant to low-dose human expo sures and which contribute to the high proportion of chemicals that te st positive, The focus of regulatory policy is on synthetic chemicals, although 99.9% of the chemicals humans ingest are natural. More than 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'' produced by plants to protect themselves fro m insects and other predators: 63 have been tested and 35 are rodent c arcinogens. There is no convincing evidence that synthetic chemical po llutants are important as a cause of human cancer. Regulations targete d to eliminate minuscule levels of synthetic chemicals are enormously expensive: the Environmental Protection Agency has estimated that envi ronmental regulations cost society $140 billion/year. Others have esti mated that the median toxic control program costs 146 times more per h ypothetical life-year saved than the median medical intervention. Atte mpting to reduce tiny hypothetical risks has other costs as well: if r educing synthetic pesticides makes fruits and vegetables more expensiv e, thereby decreasing consumption, then the cancer rate will increase, especially for the poor. The prevention of cancer will come from know ledge obtained from biomedical research, education of the public, and lifestyle changes made by individuals. A reexamination of priorities i n cancer prevention, both public and private, seems called for.