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Science has ‘sort-of’ good news

March 24, 2008

by Roz Kohls

The National Institute of Health and the Environmental Protection Agency have decided, at long last, that administering chemicals to rats in high doses does not reliably predict human risk of cancer or anything else.

This is good news because those tests for carcinogens have been used to condemn chemicals and produce false positive findings on all kinds of natural substances that we eat, breathe, and drink every day, according to Gilbert Ross, MD, medical director of the American Council on Science and Health.

Sometimes the results were exactly contrary for the same substance. Remember the coffee scare? Scientists claimed if you drank coffee, it would give you cancer. A few months later, scientists claimed drinking coffee prevented cancer.

I can understand why scientists conducted the tests on rats instead of humans. That was certainly an ethical way to do the tests. However, rats’ tissue isn’t much like human tissue.

Also, scientists used extremely high doses of the chemical being tested on the rats. The quantity used was way out of proportion to the difference in sizes between rat and human.

In the “coffee” tests for example, no human could possibly consume that much coffee. It was almost as if the scientists believed any risk, no matter how tiny, was too much.

Also, the scientists who tested rats for carcinogens didn’t seem to use common sense and consider other factors. In the coffee tests, for example, were there large numbers of coffee drinkers who had stomach cancer? If there weren’t any statistical clusters indicating a common denominator, why wasn’t that considered before publishing the results?

The good news is that those kinds of tests are out now.

Scientists are replacing the rat tests with testing carcinogens on cells and “isolated molecular targets” using high-speed automated screening robots, Ross said.

This is obviously cheaper and faster, and will save the lives of many lab rats. The question remains, though, will scientists use common sense when analyzing the results?

That’s why this is “sort of” good news.

If the new tests produce chemically-induced cellular abnormalities, will it be taken as conclusive evidence? It will, if researchers expect “zero risk.” It won’t matter to the testers if there are no clusters of deaths or cases of illness or cancer in humans related to the substance.

“Zero risk” is an unrealistic standard. If scientists didn’t want to use common sense before, can we assume they will now?