Eat Your Vegetables, Reduce Cancer RiskCommentary by Pete du Pont
April 08, 1998
You may not be aware that you're eating and coming into contact with hundreds of potential cancer-causing chemicals every day - not from pesticides, but from nature!
The above statement is true but misleading. Despite what you may have read and heard, chemicals, whether manmade or natural, are not an important source of cancer risk.
That's the main message of a National Center for Policy Analysis study written by Dr. Bruce Ames and Dr. Lois Gold, both of the National Institute of Environmental Health Sciences Center. While more than half of all natural chemicals in fruits and vegetables that have been tested cause cancer when given in large doses to laboratory rats and mice, these tests have very little relevance for humans.
The facts are, Drs. Ames and Gold say, that not eating fruits and vegetables because of a fear of getting cancer from pesticide residues actually increases a person's cancer risk. Further, contrary to the impression many people have, cancer rates except for lung cancer have fallen 16 percent since 1950.
The authors wrote the study because they feared that misconceptions about the relationship between environmental pollution and pesticides and human disease are resulting in poor research and funding decisions in regulatory policy.
Among the study's other findings: Smoking contributes 35 percent of U.S. cancer cases (no big surprise there);
Unbalanced diets, particularly diets which are low in fruits and vegetables and high in fats and alcohol consumption, account for another one-third of cancer cases.
Reproductive hormones contribute as much as 20 percent of all cancer, with lack of exercise, obesity and alcohol intake influencing hormone levels and increasing risk.
Guess what's not a significant factor in cancer rates? Research indicates that pesticides, industrial chemicals and all other synthetic chemicals contribute to less than one percent of all cancer cases. This implies that spending cancer research and prevention dollars on preventing exposure to synthetic chemicals is misguided at best, and, according to Ames and Gold, possibly counterproductive.
Not only are fears about man-made pesticides normally not justified, but reducing their use may do more harm than good. The reason: organic fruits and vegetables are more expensive. And if higher prices cause people to buy less produce, there will be health consequences. The study reports that the quarter of the population with the lowest dietary intake of fruits and vegetables has roughly twice the cancer rate as the quarter with the highest intake.
Even nature may not cooperate with efforts to reduce the use of man-made pesticides. For example, plant breeders developed a new breed of insect-repelling celery, but this new "all natural" celery contained eight times the amount of natural carcinogens present in common celery and caused produce handlers to develop a severe rash.
To put the cancer risk from pesticides in perspective, 99.9 percent of all pesticides that humans eat are naturally produced by plants to defend themselves against fungi, insects and other animal predators. Americans eat about 10,000 times more natural pesticides per person, per day (measured by weight) than they consume in synthetic pesticide residues.
A single cup of coffee contains about a thousand chemicals, only 28 of which have been tested, and 19 of those tested cause cancer in rodents. However, people would have to drink the equivalent of thousands of cups of coffee a day to face the same risk as the rats, who ingest massive amounts of the chemicals in the tests. Ames, who doesn't hesitate to drink coffee himself, says people worry about the wrong things.
Ames developed the "Ames test" for determining whether a chemical causes cancer in laboratory animals, but now he says there is mounting evidence that it is the high doses themselves, not the chemicals tested, that cause cancer. Or to use a scientific truism, "It's the dose that makes the poison."
Two conclusions - one regarding public policy, the other regarding public health - can be drawn from this study. First, public health dollars should not be squandered fighting the hypothetical cancer risks posed by synthetic chemicals. Second, the benefits of eating fruits and vegetables far outweigh the risks. So ignore the rantings of technophobic environmentalists about the risks of pesticides and follow your mother's advice: "eat your vegetables."