TCS Daily

Toxic Shock Syndrome

By Herbert Inhaber - February 26, 2003 12:00 AM

Toxicology may sound like the most boring of subjects, but it governs most of the environmental laws and regulations on the books. Thus if it miscalculates, society may spend billions too much to clean up toxic substances. Indeed, it may be possible to save billions without jeopardizing health - and even improving health - by loosening overly strict standards.

The field was thrown into turmoil recently by an article on Feb. 13 by Edward Calabrese of the University of Massachusetts in the prestigious science journal Nature. Prof. Calabrese is not a bomb-thrower by profession, and he is the author of many books on toxicology, air pollutants and related subjects.

'The Dose Makes the Poison'

Toxicology operates on the principle that enough of any substance can injure or kill you. This was known to the natural philosopher Paracelsus about half a millennium ago, who said, "the dose makes the poison". To put it simply, every human needs some salt in the diet, since we are descended from sea creatures of billions of eons past. But one hardly has to be a graduate toxicologist to know that a diet of say 10% salt, besides being unpalatable, would make you sick or even send you to the cemetery.

Since experiments on humans are out, for obvious reasons, toxicologists feed high percentages of mercury, lead, arsenic and other toxics to rats, mice and other creatures, Some of them develop tumors, lesions or die. But then comes the public policy problem: The unfortunate rodents are being fed hundreds or even thousands of parts per million of the toxic substance. But humans are almost invariably exposed, if they are exposed at all, to perhaps a few parts per million or even parts per billion of toxic substances.

If rats were given food or water with these small concentrations, scientists might need millions of them to prove what the mathematicians call "statistical significance". Nobody has the time or money to have vast colonies of rats being fed tiny amounts of arsenic or lead, so the toxicologists make a giant leap of faith. They extrapolate down from the high doses that the rats get to low doses that humans receive, making corrections for body size and other variables.

This is how, with other complications, we get the rules that are published in the Federal Register for a myriad of potential pollutants. But Prof. Calabrese, toxicologist himself, says, "The field of toxicology has made a terrible blunder. A lot of high-powered people need to take the time to explore (what I discovered)".

'Mild Chemical Stress Is Beneficial'

Quoting about 5000 studies, Calabrese notes that in small quantities, many toxics are actually good for you. Dioxins in tiny concentrations, regarded by many as about as appealing as anthrax or the bubonic plague, can reduce tumor growth in some species. Calabrese quotes many examples and refers to his vast array of past studies.

Calabrese has support from others in the field. Anthony Trewavas from Edinburgh University says, "What we call 'toxic chemicals' is a misnomer. Mild chemical stress is beneficial".

In one sense, Calabrese is reiterating the principles of homeopathy, pioneered by Hahnemann many years ago. The principle of that science is that a small amount of an otherwise dangerous substance, say arsenic, can provide some medical benefits.

The principle was brought up to date by the coining of thew word "hormesis" about 60 years ago. This again refers to a possibly beneficial effect of small amounts of something that's lethal in high concentrations. For example, after Hiroshima everyone on Earth knows that high radiation doses are extremely hazardous. But some of us go out of our way to avoid even the slightest radiation dose. Some will drive miles out of their way to avoid passing near a nuclear reactor, although the dose they would get by driving by the gate could not be detected by the most sensitive radiation detector.

But Prof. T. D. Luckey has performed the same service for radiation as Calabrese has for toxicology, noting that hundreds of studies have demonstrated that small doses of radiation either cause no effect or may promote health. To give a simple example, Coloradans get more radiation than most Americans. Because of their elevation, they get more cosmic rays. Yet the Colorado Chamber of Commerce promotes the state as one of the most healthful.

So Prof. Calabrese has performed a great public service by thinking out of the box. It will not be easy to change allowable levels of toxic substances, because of the powerful special interests that profit from present standards. But the good professor has thrown a pebble down the mountainside that may eventually become an avalanche.

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