Evaluating dietary carcinogens.

A much-cited 1981 study concluded that some 35 percent of human cancer deaths probably trace to carcinogens in foods-both synthetic chemicals, such as pesticides and food additives, and naturally occurring ones, like fungal toxins.

To get a better fix on the risks posed by such compounds, the National Research Council in Washington, D.C., set up a committee to study the amounts and toxicity of these chemicals in food and to compare them to data on the occurrence and potency of natur al cancer-fighting agents.

The committee's findings appear in "Carcinogens and Anticarcinogens in the Human Diet," a 417-page report issued on Feb. 15. Overall, its tone is reassuring, arguing that "the great majority of individual naturally occurring and synthetic chemicals in the diet appears to be present at levels below which any significant adverse biologic effect is likely, and . . . [thus] are unlikely to pose an appreciable cancer risk."

These compounds don't occur individually, however (SN: 7/3/93, p. 4). The report concedes that important questions remain regarding how to assess risk from the interaction of the tens or even hundreds consumed daily-each in what might represent a nontoxic quantity.

While much attention has been focused on the potential risks posed by pesticides and other agricultural chemicals in food, the new analysis argues that when it comes to cancer, "natural components of the diet may prove to be of greater concern." It points out that naturally occurring carcinogens function much as synthetic ones do, tend to occur in higher numbers, have been less well studied, and have largely escaped regulation.

For perspective, the study concludes, health risks posed by carcinogens in food tend to pale in comparison to those posed by gluttony-especially the overeating of foods rich in fat.

While food analyst Richard Wiles of the Environmental Working Group in Washington, D.C., agrees, he remains worried about those unknown risks associated with the mix of low-level carcinogens in our diet. Indeed, he argues, given that some carcinogens natu rally taint foods, "why shouldn't we be concerned about adding synthetic ones?"