Document Raq5r1yO7jdEwyROx82vdRQ6z

News of the Week / UfM- 05108 DIET, WORKPLACE CALLED CANCER FACTORS Saying that "most common cancers are potentially preventable/' a Na tional Research Council committee has begun recommending general di etary guidelines to reduce the risk of cancer. Despite their mildness and similarity to guidelines publicized by the National Cancer Institute two and a half years ago (C&EN, Oct. 15, 1979, page 20), the NRC com mittee's report has been criticized instantly. In a separate but topically related development, epidemiologists who study cancer incidence are calling for "continued vigilance in the workplace and environment" to pre vent cancer. They are acting on the basis of a recent analysis which, in part, contradicts another widely dis cussed epidemiologic study that played down the importance of such risk factors for cancer (C&EN, Aug. 17,1981, page 32). The National Research Council, the research arm of the National Academy of Sciences in Washington, D.C., was commissioned by the Na tional Cancer Institute to prepare its report, "Diet, Nutrition, and Can cer." The ad hoc committee respon sible for that report consisted of 13 scientists from the U.S. and Cana da, including chairman Clifford Grobstein, professor of biological sci ences and public policy at the Uni versity of California, San Diego. The epidemiologists whose study refers to the importance of the workplace and the environment in clude Devra Lee Davis, who recently moved to the Environmental Law Institute in Washington, D.C.; her former colleague at Johns Hopkins University in Baltimore, Kenneth Bridbord; and Marvin Schneiderman, a consultant with Clement Associ ates, also in Washington. The principal trend to which Davis and her colleagues wish to direct scrutiny is that of increasing cancer deaths among older men in the U.S. These epidemiologists discern an in crease in deaths due to cancer among men between the ages of 45 and 65 in the U.S. However, the trend is opposite for men below the age of 45, they note, with a drop in cancer mortality of about 40% since 1950. Davis also draws attention to in creases during the past several dec ades of the bulk manufacture of chemicals that are known to cause cancer in humans, including a dou bling of "synthetic carcinogen pro duction" in the past decade. Any effects of this increased manufacture on cancer incidence, either among workers or in the general populace, won't be known "until the end of the century," she says, adding: "Those who say we have no prob lem are jumping the gun." Thus she takes issue with a study published last year by British epidemiologists Richard Doll and Richard Peto. They Dietary gukteflnes may help reduce cancer rtak The Committee on Diet Nutrition & Cancer of the National Research Coun cil says the foHowtng guidelines are "consistent with good nutritional prac tices end likely to reduce the risk of canoer." Moreover, the guidelines ougN to be followed in "their entirety" for maximum benefit. Consumption of fats should be reduced from the curent level of ebout 40% to about 30% of total calories in the diet--"a moderate and practical target." The daily det should include fruits, especially those rich In vitamin C; veg etables, particularly those rich In caro tene and also members of the mustard family; and whole grains. However, taking of supplements of minor nutri ents found in these foods is not rec ommended, inasmuch as high doses are "potentially toxic." Foods cured or pickled with salt and smoked foods should be "mini mized" in the diet. Contamination of foods with car cinogens "from any source" should continue to be minimized. "Intentional additives" should continue to be eval uated before approval for use In foods. Mutagens in foods should be iden tified and tested for their ability to cauae cancer. Where "feestoie and prudent," mutagens should be "re moved" or their levels "minimized." Any drinking of alcohol, particu larly by smokers, should be done "in moderation." concluded that cigarette smoking could account for the only discerni ble general increase in cancer mor tality. Davis says that chemical exposure, infectious disease inci dence, and nutrition also must con tinue to be scrutinized- A wide group of experts, includ ing Doll and Peto, agree that nutri tional factors probably play an im portant role in cancer. The NRC committee also agrees, but says "pre cise estimates of diet's contribution are not yet possible." Nonetheless, says chairman Grob stein, "We recognize we should try to put what we learn to use as soon as possible. By controlling what we eat we may prevent such dietary cancers." Thus the NRC committee has formulated rather mild and "inter im" recommendations for the gen eral population. These recommenda tions are explained carefully and qualified cautiously by the commit tee. The committee adds an even more general caveat: "It is not now possible, and may never be possible, to specify a diet that protects all people against all forms of cancer." The critics of the committee's guidelines are arguing that it may not be possible to specify a diet that are the meat suppliers. Representa tives of the American Meat Insti tute and the National Meat Associ ation, both headquartered in Wash ington, D.C., greeted visitors to the NRC press conference with state ments offering instant criticism of the cancer-diet report That criticism also draws atten tion to inconsistencies within NRC, and in particular to the stance taken by NRC's Food & Nutrition Board two years ago regarding dietary guidelines (C&EN, June 2, 1980, page 6). Board member Robert E. Olson, a biochemist at St Louis Uni versity school of medicine and a principal author of that FNB report, also is critical .of the new NRu re port, calling it "premature. My basic philosophy is don't make public health recommendations unless you're sure of a benefit," he says. Grobstein defends the NRC re port, saying: "1 don't thnk we're pushing any unproven theories." 4 C&EN June 21, 1962