Natural carcinogens in food pose a far greater danger than pesticides and additives and account for more than 98 percent of the cancer risk in the diet, a government scientist has said. Even a minor reduction in these naturally occurring hazards would surpass the benefits of eliminating all traces of dangerous manmade chemicals, said Dr. Robert J. Scheuplein, director of the Office of Toxicological Sciences at the U.S. Food and Drug Administration (FDA).
The culprits include not only such recognized health hazards as fats and beer but such seemingly safe products as bread, yogurt, mushrooms and many spices.
"The risk is from natural carcinogens in the diet, because they overwhelm all the others," he said Monday.
This does not mean that all food is dangerous or even that people can do much about the hazard. Instead, Scheuplein's analysis was intended to focus attention away from what he sees as a largely bogus health issue _ the hazards of chemical contamination.
He contended that the public is worried about the wrong risks in their diet, in part because of exaggerated news accounts of such scares as Alar in apples, cyanide in grapes and dioxin in milk.
Scheuplein based his conclusions on a statistical analysis of the quantity of cancer-causing agents in the diet.
He said the risk of dying from cancer from dietary exposure to both natural and manmade carcinogens, or cancer-inducing substances, was 7.7 percent. The risk from naturally occurring carcinogens alone was 7.6 percent.
Scheuplein presented his findings at a meeting of the American Association for the Advancement of Science.
Dr. Frank Young, a former FDA commissioner who is now deputy assistant secretary of Health and Human Services, said he agreed with Scheuplein's contention.
"The headline should not be, "All Foods Cause Cancer' or "Drop Dead. Don't Eat,"' Young said. "The good news is, let us not as a nation focus just on the technological food additives. We ought to focus on the big issues as well."
Federal law requires the FDA to ban food additives known to cause cancer in humans or animals, but technological advances in recent years have enabled scientists to detect traces of carcinogens in virtually every food.
As a result, the FDA and the Environmental Protection Agency, which regulates pesticides, have in recent years attempted to concentrate on major risks and ignore insignificant ones.
Scheuplein said the main carcinogen is fat, which has been linked to several kinds of tumors. However, he said most foods would not pass safety tests required for new food chemicals and additives.
He estimated that carcinogens make up one-tenth of 1 percent of the food people eat. Among concerns he cited were:
High-protein foods, such as meat and eggs, contain bacterial substances that can cause genetic mutations. An ordinary day's protein can be as damaging to the genes as five cigarettes.
Hazardous urethane is a natural product of fermentation. It is present in beer, yogurt, bread and other foods.
Mycotoxins produced by molds are common in many foods, especially when stored in warm, humid conditions. Aflatoxins occur in corn and peanuts, zearalenone in soybeans and luteoskyrin in yellow rice.
Smoked or salted fish and pickled vegetables may cause digestive cancers. This is attributed to nitrates and funguses.
Grilling and charring fish or meat can produce potentially hazardous substances, such as nitropyrenes.
Many spices contain questionable substances. There is estragole in tarragon, eugenal in cloves, cinnamaldehyde in cinnamon, myristicin in nutmeg and anethole in fennel. Several spices, including oregano, marjoram and bay leaves, may cause genetic damage.
Other naturally occurring carcinogens include d-limonene in oranges, psoralens in celery, hydrazines in mushrooms and nitrates in spinach.
Because federal money is in short supply, Scheuplein said the FDA should change its research focus to concentrate on the total diet and move away from "the notion that you can ban one or two substances and have an effect."
_Information from Reuters was used in this report.