Return to Medical Research On-Line Resources

Slow Learners Or What?






The above are headlines and titles that appeared in the March 23, 1993 issue of the New York Times. Brief excerpts of the three-part series of articles follow:

The use of rodents as a diagnostic tool for identifying health hazards is being met with growing skepticism because of evidence that chemicals frequently have wholly different effects in animals than in humans. Dr Kenneth Olden, director of the National Institute of Environmental Health Services, reviewed tests in his laboratory in Research Triangle Park, N.C.

By the time Dr Olden took over as a director of the Health Sciences Institute in 1991, the animal studies were increasingly being called into question. Almost immediately, he empaneled a group of the nation's leading experts to study his agency's toxicology-research program to help him decide whether to look for a new approach.

Last summer, the group's report said many of the assumptions driving the rat and mouse research "do not appear to be valid." The experts particularly questioned the practice of feeding rodents the "maximum tolerated dose" of the chemical being tested, the MTD, as it is called..."The problem is we don't know what the findings really mean," Dr Robert Maronpot, chief of the institute's experimental-pathology laboratory, said of the animal studies.

As illustration, Dr Allen J. Wilcox, chief of the institute's epidemiology branch, cited a recent institute study showing that rodents consuming cola beverages "showed an association between the cola beverages and renal failure," or loss of kidney function...

Another study, completed about a year ago, found that rats and mice develop cancer when fed high doses of oxazepam, a direct chemical relative of Valium. Valium is among the nation's most-often prescribed drugs, and the rodents taking the maximum tolerated dose of oxazepam "had a 100 percent incidence of tumors, all over the body - very quickly," Dr Maronpot said...

Dr Maronpot swept his hand toward a long row of blue books stetching more than 10 feet along an upper shelf, reports on all 450 animal studies the Government has conducted over the last 30 years.

"It's an impressive product, not produced by anyone else in the world," he said. Still, Dr Maronpot acknowledged, neither he nor anyone else at the institute knows how many of the tested substances that produced tumors or other harmful effects in animals - about half the total - might now be shown to be benign at normal levels.

Even more worrisome, perhaps, is the opposite question: How many substances that caused no harm to rodents might be dangerous to humans? One chance finding demonstates this problem.

"Arsenic is not a carcinogen in animal studies," said Dr Joseph F. Fraumeni, director of epidemiology and bio-statistics at the National Cancer Institute. But several years ago, he recalled, a study of smelter workers exposed to high levels of arsenic in the air showed a high level of lung cancer.

From that, Dr Olden's review committee concluded that the Government should no longer rely on animal studies...

...the institute and the rest of the Government can seldom offer much more than the animal studies as warnings of a substance's possible danger to humans...

Quite often, that means no one takes the institute's warnings seriously any longer.

Almost two years ago, the results came in from rat and mouse studies of 1,2,3-trichloropropane, an industrial solvent used as a paint and varnish remover or a degreasing agent.

Almost every animal exposed to the substance was riddled with tumours "in several organs," said Dr Richard D. Irwin, the institute toxicologist who wrote the report. "This is the type of chemical that shows the greatest potential for human effect."

"Our understanding is that workers wash themselves in this," Dr Griesemer said. And since the chemical is absorbed in the skin, he and others said, the finding was particularly troubling.

In Dr Irwin's view, "It would be real good to get some human data because I'm sure there were people who were exposed to it in the past, maybe even now."

So did the epidemiologists look for people who had been exposed to the substance?

"This isn't one we're looking at," Dr Wilcox said...

In 1990, when a rodent study suggested that fluoride might be a carcinogen, "we took that one on," said Dr Fraumeni, head of epidemiology for the cancer institute. "We found nothing, and that was the last time."...

"We always have a battle on the issue of what to do with the animal data," Dr Stein added. "I'm not trying to downplay it, but I do believe other things ought to have priority."

So back in North Carolina, Dr Irwin said: "I really haven't heard of anything happening. It's almost as if our work just goes into a black box."

Acknowledging that problem, Dr Olden said: "I have to say we don't serve the American people very well right now. But that's where we are."

For much of the last two decades, [animal] studies have been the Government's most important diagnostic tool for identifying environmental problems that are health hazards and setting priorities for Federal regulations.

But now the animal-studies program is being hobbled by doubts about its worth. So much evidence has accumulated that chemicals frequently have wholly different effects in animals and humans that officials throughout Government and industry often do not act on the studies' findings.

And with the growing skepticism, the rationale behind a large portion of the nation's environmental regulation is thrown into question...

So there we have it. These admissions come now despite the fact that for well over a century intelligent and honest doctors and scientists had been fervently warning of the futility and stupidity of trying to apply to humans the results obtained from experiments that are carried out on entirely different biological entities. But then, this is not the first time the so-called experts have criticised the unscientific and misleading nature of their animal experiments - they have done so before on numerous occasions - but, only when it is in their own interests. The very fact that animal experiments are not reliable is its virtue to promoters. "So, if animal experiments are misleading, they are at least flexible: they can be deemed inapplicable when necessary, ignored when convenient and used to imply important advantages..." (Dr Robert Sharpe)

Return to the Top

Published in the Winter 1993 issue of the CAFMR Newsletter - Campaign Against Fraudulent Medical Research,