America's War on "Carcinogens": Reassessing The Use of Animal Tests to Predict Human Cancer Risk

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Please click here to download and view an 11-minute video synopsis of America's War on "Carcinogens" -- the book in which ACSH urges changes in the current regulatory approach to assessing human cancer risk on the basis of high-dose animal tests.

Click to watch/listen to the Jan. 26, 2005 Cato Institute press conference for the book.

Go here for information on the March 16, 2005 Manhattan Institute breakfast/speech about the book.

Go here for information on the April 19, 2005 Pacific Research Institute breakfast/speech about the book in San Francisco.


As we went to press with America s War on Carcinogens, we had just passed a dubious national anniversary: November 2004 marked the forty-fifth anniversary of America s first major carcinogen scare. Just prior to Thanksgiving, a federal official announced that there was a cancer-causing chemical in the cranberry crop and the safety of one of the staples of holiday dinner was immediately in doubt. Americans panicked and threw out their cranberry sauce.

The great cranberry scare of 1959 was the first of many cancer scares. What do these scares have in common? They were based on the observation that the chemicals in question caused cancer when fed to laboratory animals in high doses.

But do the results of high-dose animal cancer tests in themselves allow us to accurately predict human cancer risk? In ACSH s bold new book, scientists come together to consider that question, and respond with a resounding and paradigm-shifting no.

Animal testing is a critical part of modern biomedical research. But so is common sense. As you will read in the pages that follow, laws, regulations, and even the popular wisdom have come to accept the mouse is a little man concept, the argument that since we cannot test chemicals on people, we need to rely on animals as our surrogate. In some ways this is true, and what ACSH asserts is not that we should discount animal testing but that we should interpret the results of such tests in a more sophisticated (and less knee-jerk) manner.

At this time, there are laws and regulations in effect that are premised on the assumption that if a high dose of a chemical causes cancer in a laboratory animal, we must, out of caution, assume that it will also increase human cancer risk, even if the human exposure is extremely low in comparison.
For example, the Delaney Clause, part of the 1958 Food, Drug, and Cosmetic Act, requires that the FDA ban from the food supply any synthetic chemical that causes cancer in animals. No ifs, ands, or buts about it. The law (and ones similar to it, including California s Proposition 65) focuses considerable amounts of our cancer-fighting resources on the purely hypothetical risks of trace environmental chemicals solely because those chemicals have been designated carcinogens in animals. The ongoing attempt to purge our air, water, and food supply of traces of any synthetic chemical that causes cancer in animals is suspect in itself, but it becomes even more absurd when one considers that nature abounds with chemicals (including those in the natural food supply) that cause cancer in animals. The more we test both natural and synthetic chemicals on animals, the more of them we must classify as carcinogens.

Cancer is the second leading cause of death in the United States. Effective cancer prevention measures should be among our top priorities in public health. But we will never succeed in reducing our nation s cancer toll if we continue to focus on trace levels of chemicals that cause cancer in animals but have never been shown to cause human cancer at the levels of typical human exposure.

The time is long overdue to call for a national reassessment of the use of animal cancer testing to predict human cancer risk.

American consumers should not be subject any longer to the carcinogen du jour scares that have dominated the headlines for the past five decades. Corporations should not be forced to withdraw perfectly useful and safe products from the market (or take unnecessary efforts to purge chemicals from the environment) just because a substance is labeled an animal carcinogen. In our pursuit of methods to reduce the risk of cancer in America, science and common sense, not rhetoric, scare tactics, and hyperbole, should prevail.

In this book, scientists associated with the American Council on Science and Health call upon Congress, the National Cancer Institute, the National Toxicology Program, our nation s regulators, scientists from many disciplines, as well as members of the media to step back from the familiar but scientifically baseless mantra that if it causes cancer in animals, it must be assumed to be a human cancer risk. Such a simplistic, unscientific, inconsistent approach to ferreting out risks for human cancer is a losing strategy in the war on cancer.

Elizabeth M. Whelan, Sc.D., M.P.H., M.S.
American Council on Science and Health
December 2004
New York City

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