By Elizabeth M. Whelan, Sc.D., M.P.H.
Posted: Monday, November 29, 2004

EDITORIAL
Publication Date: November 25, 2004

FORTY-FIVE years ago this week, in November, 1959, most Americans cel ebrated Thanksgiving sans cranberry sauce. Earlier that month, a government health official had announced that traces of the weed killer aminotriazole — a chemical that caused cancer in rodents — had been found in the cranberry crop. The spokesman urged housewives to "be on the safe side" and refrain from buying cranberries because the rodent data suggested that the "contaminated" cranberries could pose a human cancer risk.

There was never any real health risk.

The cranberry scare of 1959 marked the beginning of a modern wave of "chemical phobia" and a government assault on synthetic chemicals that, at high doses, caused cancer in laboratory animals.

This "war on carcinogens," which is still in full force today, had its legal origins in the Delaney Clause, a 1958 amendment to the Food, Drug, and Cosmetic Act that prohibited the presence in food of any synthetic chemical that caused cancer in animal studies.

Cranberry phobia, which burst on the scene a year after the Delaney Clause was passed, was soon followed by a spate of other chemical scares, including those focused on nitrite in bacon, the sweeteners saccharin and cyclamate, and the agricultural chemicals EDB and Alar. More recently, questions have been raised about the safety of French fries (and other high-starch foods cooked at high temperatures) because the process can generate acrylamide. All of these "carcinogen du jour" scares were based solely on the observation that the chemical in question caused cancer in rodents.

But is there sound scientific evidence that high-dose animal tests can accurately predict human cancer risk? Many scientific studies and scientific experts tell us that the resounding answer is "no."

America's "war on carcinogens" was predicated on a number of assumptions — all of which we now know are false:

* Only a small number of chemicals are carcinogenic — so let's get rid of them.

Actually, a surprisingly high percentage of chemicals — 50 percent in some tests — test positive in animal carcinogenicity studies. A likely explanation for many of these positive results is that toxicity at high doses, not the chemical per se, leads to increased cell turnover, which in turn boosts cancer risk.

* If it causes cancer in one species, it will cause cancer in all animals — including Man.

 

In reality, not all substances that induce tumors in one species do so in another. In many instances, findings in mice do not predict cancer risk in rats, two rodent species that are far more closely related to one another than either is to humans.

* Since chemicals (mainly in occupational exposures) that cause cancer in people also cause cancer in animals, the predictions work the other way as well.

Not so. Very few chemicals shown to be animal carcinogens have ever been linked later with human cancer risk.

* Only synthetic chemicals are carcinogens, not natural chemicals.

Wrong again.

For example your upcoming 100 percent natural Thanksgiving dinner will be brimming with carcinogens, including the hydrazines in the mushroom soup, heterocyclic amines, acrylamide, benzo(a)pyrene, safrol and quercetin in the roast turkey and stuffing, coumarin, acetaldehyde and methyl eugenol in the apple and pumpkin pies and benzofuran, caffeic acid and 4-methylcatechol in the after-dinner coffee. None of these substances pose a health hazard.

Animal testing is essential to biomedical research. But so is common sense. A positive result in a few high-dose animal tests is not sufficient evidence to allow us to conclude that a chemical poses a human cancer risk.

Over-reliance on animal carcinogenicity testing as a predictor of human health risks has diverted both public attention and resources from important and proven causes of cancer. Unfounded cancer scares cause economic disruption as useful, safe products are banned — and replaced with more expensive, inferior alternatives (the 1959 cranberry panic had a devastating effect on the growers).

Earlier this month, the Bush administration, in addressing environmental policies for Bush's second term, pledged "to employ the best science and data to inform our decision-making." The elimination of the scientifically baseless mantra "if it causes cancer in animals it must be assumed to be a human cancer risk," would be an excellent place to start.

Dr. Elizabeth M. Whelan is president of the American Council on Science and Health and an editor of ACSH's forthcoming book "America's War on 'Carcinogens': Reassessing the Use of Animal Tests to Predict Human Cancer Risk."

Source Notes:  
New York Post