The Public Policy

Jumping Ship From the Rats

In a startling development, federal regulators agree that administering chemicals to rodents in super-high doses does not reliably predict human risk.

By 3.19.08

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We won! That is, the forces of science-based public health policy seem to have won -- if not the war, at least a major battle. At long last, federal risk assessors and regulators have come around to the view that administering chemicals to rodents in super-high doses does not reliably predict human risk -- of cancer, or anything else -- and that a better method needs to be employed, if we are to avoid more unnecessary bans, anti-chemical media hysteria, and activist crusades.

High dose animal tests on one rodent species don't reliably predict cancer risk in another rodent type, much less in humans. The same tests for "carcinogens" that are used to condemn synthetic chemicals also give false positive findings for a whole spectrum of natural substances that we safely eat, breathe, and drink every day.

The sort-of good news is that the National Institutes of Health (NIH) and the Environmental Protection Agency (EPA) just announced a new collaboration: the development of a "new paradigm" for testing potentially toxic chemicals. Drawing upon the unique testing methodologies to be found in their various sub-agencies, they plan to shift from testing chemicals on whole animals to testing the chemicals on cells and "isolated molecular targets," using high-speed, automated screening robots.

It sounds a bit science-fictiony -- a brave new world, perhaps, of chemical toxicity testing. Bypassing the high dose, long-term animal experimentation for test "subjects" -- cells -- in Petri dishes will undoubtedly save the government testers a lot of money (and also spare the lives of many rats and mice). But the real question is, will it bring some sense to the testing process for evaluating suspected chemical toxins?

ONE GOOD THING can be deduced from this new collegiality. It seems to be a clear (and overdue) acknowledgment of what my colleagues at the American Council on Science and Health have been telling federal risk assessors (and the public) since our group was founded in 1978: the old way of testing for chemical carcinogens is not valid. In our 2005 book America's War on "Carcinogens", we warned against allowing high-dose rat tests to paint us into a regulatory corner -- leading to bans and restrictions on hundreds of chemicals merely because rodents became ill after long periods of high exposure.

Forty-plus experts in various relevant fields reviewed our publication and agreed with our conclusions: high-dose animal tests do not predict human toxicity or cancer risk. Yet, when we tried to get someone in the regulatory bureaucracy to acknowledge this fact -- well known to toxicologists for decades -- we were met with either stony silence or the disingenuous, "Well, we know, but we've been doing it this way for years, and we have nothing to replace it with." Not a resounding endorsement for a system that has cost our economy billions in regulatory compliance efforts over decades.

DURING THE CREATION of our book, we asked the then-director of the Harvard Center for Risk Analysis, George M. Gray, Ph.D., to review it. He was so enthusiastic, he agreed to write its preface, and he stated (among other things) that animal testing was "badly flawed." Relying on such tests "can have important public health consequences." Gray added: "It is important for public health [that this book] be heeded."

However, some months later, when we (with the help of the Washington Legal Foundation) petitioned the EPA to re-assess its approach to carcinogen testing based on our book, who was the EPA assistant administrator who, after months of stonewalling, rejected our brief?

The same Dr. Gray. Yet now he has turned up again as a co-author of the article announcing the "new paradigm" (a phrase echoing from our book) in chemical testing.

So is a new era coming, one in which real toxins and carcinogens will be weeded out from the countless hypothetical and negligible ones that we have spent the past fifty years (and billions of dollars) pointlessly fighting? That's still up in the air. My gut reaction is to say it can't be any worse than the useless current method.

But of course, it can be. If the new high-output micro-assays do show chemical-induced cellular abnormalities, will that now be taken as conclusive evidence of increased human risk, without further confirmatory evidence? This is an all too likely scenario in our "zero-risk" environment. If so, the efficiency of the new testing paradigm could lead to even more chemicals being regulated than is now the case using (more lengthy and tedious) rodent tests.

So before we start celebrating, we should remember to be careful what we wish for. The larger mission of basing regulatory policy on scientific sense has not yet been accomplished.

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About the Author

Gilbert Ross M.D., is executive and medical director of the American Council on Science and Health.