reproduced from

VOL. 7 NO. 29

Vicky Getty, MEd, RD and Bill Evers, PhD, RD
Cooperative Extension Foods and Nutrition Specialists
School of Consumer and Family Sciences, Department of Foods and Nutrition, Purdue University, West Lafayette, IN

Over the years, the public has heard from the media and consumer groups that synthetic chemicals in food are a major factor in the development of cancer. The report below, from one of the most well-known inventors of a standard test for cancer- causing chemicals and a colleague, helps put into perspective what the real concerns ought to be. This article could make an
excellent "put it in perspective" piece for any program on cancer and food.

Summarized from FOOD CHEMICAL NEWS, April 28, 1997, pp. 18-19.

In April, biochemical researchers at the University of Californiaat Berkeley told the American Chemical Society that synthetic chemicals in the human diet are not a significant cause of cancer.

According to Bruce Ames, professor of biochemistry and director of the National Institute of Environmental Health Sciences Center (NIEHSC) at Berkeley, and Dr. Lois Gold, director of the
Carcinogenic Potency Project at NIEHSC, several myths about environmental chemicals in food have grown over the years. Citing pesticide residues as an example, the researchers said that the public and government have a mistaken impression about the impact of these chemicals on human health.

They said, "The U.S. spends 100 times more to prevent one hypothetical, highly uncertain death from a synthetic chemical than it spends to save a life by medical intervention." More harm
than good might come of regulatory attempts to reduce these "tiny hypothetical risks," according to the two researchers. They warned that such attempts might make farming less efficient, causing increases in the cost of fruits and vegetables. The increased cost could put these foods beyond the budgets of the poor. Ames and Gold voiced the opinion that eating fruits and vegetables is one of the most important things a person can do to ward off cancer. They also mentioned quitting smoking and controlling infections as important cancer-preventing measures.

In a more general discussion of cancer, Ames and Gold noted in their report that, contrary to the popular belief that the frequency of cancer is rapidly increasing, cancer rates have actually declined 15% since 1950, if the figures are corrected for age and lung cancer caused by smoking is removed. The types of cancers that have gone up in the last 40-50 years are not the ones that seem to be affected by food choices, according to the researchers. Two examples they provided were rates for lung cancers and melanomas [skin cancers].

Ames and Gold also stated that cancer "is one of the degenerative diseases of old age, increasing exponentially with age in both rodents and humans." Even with the best efforts to reduce the risk of cancer, the two noted that cancer is due partially to normal aging and will still occur at some age in some people.

It is the buildup of oxidative damage to DNA and other macromolecules over a lifetime that is responsible for aging and its degenerative diseases, according to the report. Normal metabolism produces byproducts, such as superoxide, hydrogen peroxide, and hydroxyl radicals, which are the same oxidative mutagens produced by radiation. These byproducts and actual mutations accumulate with age, Ames and Gold wrote. One of the defenses against these byproducts are antioxidants, including vitamins C and E and carotenoids, most of which come from dietary fruits and vegetables.

The researchers argued that the Environmental Protection Agency and other government regulatory agencies may increase the cost of pesticide use by increasing regulations for pesticide registrations. In turn, farmers might use less pesticides and thereby increase the risk of crop loss due to insects and other pests. The final result will be more expensive fruits and vegetables, "thereby decreasing consumption, then cancer will be increased, particularly for the poor," wrote Ames and Gold.

Getting back to their focus on chemicals in food, Ames and Gold challenged the belief that synthetic chemicals are the main cancer hazards to which humans are exposed. According to their argument, 99.9% of the chemicals humans ingest are natural, including substances produced by plants to ward off fungi, insects, and other animal predators. The average American ingests about 5,000 to 10,000 different natural pesticides, according to Ames and Gold.

The researchers questioned the use of high-dose animal cancer tests to assess cancer risk to humans. They noted that about half of all chemicals, natural or synthetic, studied in standard animal cancer tests are rodent carcinogens. Such a high percentage of chemicals being carcinogens is not what would be expected and is highly suspicious, according to Ames and Gold. They pointed out that in standard cancer tests rodents are given the maximum dose of a chemical that the mouse or rat can tolerate. "Evidence is accumulating that it may be cell division caused by the high dose itself, rather than the chemical per se, that is increasing cancer rate," Ames and Gold stated.

The belief that synthetic chemicals are a big danger has led to a greater than needed focus on the testing of these chemicals, according to the researchers. They observed that synthetic chemicals account for 77% of the 559 chemicals tested in long term studies in both rats and mice, and added, "There is an enormous background of naturally occurring rodent carcinogens in typical portions of common foods that cast doubt on the relative importance of low-dose exposures to residues of synthetic chemicals such as pesticides. A committee of the National Research Council/National Academy of Sciences recently reached similar conclusions about natural vs. synthetic chemicals in the diet."

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