January 09, 2003

High Bad, Low Good

Hormesis. Sounds kind of odd, but it's the idea that high doses of a compound are a poison, low doses are a tonic. Dr. Edward Calabrese advances the theory of Hormesis based on thousands of studies performed on all kinds of organisms. The proposed mechanism is that the low doses stimulates the body and the response is beneficial - for instance, a low dose of radiation causes a small amount of DNA damage which stimulates the body to repair it - if the dose is low enough, the repair exceeds the damage do to the radiation. Too high, and you die. It's hard to build a therapy around, but it does mean we might not have to sweat the small stuff - for instance, there is a point past which cleaning up certain pollutants is actually counter productive, let alone pointless. And the EPA's linear dose models would need to be changed. Still, it's not widely accepted.

This passage caught my eye in the article:

In one session of the conference, veterinarian Dennis Jones, of the Agency for Toxic Substances and Disease Registry in Atlanta, presented recent findings on low-dose mercury exposure. Jones analyzed data from a study at the Centers for Disease Control that tracked more than 100,000 infants. The infants were given thimerosal, an organic compound of mercury used as a preservative in vaccines. The researchers worried that giving the infants too many vaccines might harm them. But Jones found that limited exposure to mercury actually lessened the children's chances of developing neurological tics, delayed speech, and other pathologies. Jones's analysis is preliminary, so he declined to give concrete numbers. But he called the study "exquisite" and said that it "really amazed" him. Calabrese was not amazed. "In our most recent database search," he said softly into the microphone, "mercury is perhaps the most studied element showing a hormetic effect."

So while there's no scientific evidence so far that mercury in vaccines cause autism, if hormesis is accurate, then there might actually be a benefit to mercury in vaccines. I can see why it's hard to accept.

Posted by Kevin Murphy at January 9, 2003 02:43 PM | Science
Comments
We welcome comments. However, use no profanity and be civil.

Sounds a little bit like the underlying theory behind "homeopathy", whereby toxins with specific effects, given in small doses, supposedly mitigate their normal effects.

But there's quite a gap between showing mercury works this way, in particular cases, and showing that "hormesis" is a viable idea, across the board.

Posted by: Hormesis? at January 9, 2003 03:35 PM

From reading a little about it, I got the impression the hormesis scientists weren't too happy about the association with homeopathy. I guess the two big differences are that in homeopathy you try to dilute as much as possible (I vaguely recall some anti-homeopathy person claiming that the dilution was so great that there wasn't even a molocule of the "agent" left), where the hormesis people say a particular dose range is important; and the hormesis hypothesis is based on scientific studies.

Also, mercury is just one of many toxins that purportedly show this effect. The paragraph about it only caught my eye because of the current controversy over whether mercury can cause autism. I got the impression from the two articles linked and others that it was the fact that so many compounds seemed to show this behavior that Dr. Calabrese was attracted in the first place. It's really a two part problem - where there's data on low dosages of toxins (any toxins), it seems to show there can be benefits. Hormesis is a hypothesis to try to explain how that can happen.

Posted by: Kevin at January 10, 2003 11:18 AM

Biological systems display phasic dose response curves. There are virtually thousands of examples of paradoxical microdose phenomena in the literature. As concerns ultra-molecular phenomena: this is at the very threshold of our technical means to investigate. I would point you to a very well controlled study: Hamman B., Konig G & Him Lok K. 'Homeopathic Gibberellic Acid and Barley Germination' Homoepathy Vol 92 No 3 July 2003 Publ. Churchill Livingston. (Formery British Homeopathic Journal) ISSN 1475-4916 pp140-144

Posted by: Russell at November 4, 2003 10:29 AM

hormesis is a facinating topic and has been giving E.J. Calabrese a fantastic amout of exposure and his paper is referenced all over. But yet what I do not like to see is the non-scientific interpritation of his theory in the general media. In the past week tons of articals on "If it doesn't kill you it makes you stronger" have proposed that hormesis is going to change enviromental policy. This is complete garbage, we are not going to start lifting bans and deregulating polution to suppliment ourselves with trace amounts of toxic chemicals. A true scientist simply finds this and interesting and logical result but its actual impact will be minor.

Posted by: Chemist at December 12, 2003 03:21 PM

hthujjgnjknhgjkjjkjtttujgtuthtuhuuutuutuuthutu

Posted by: La-shan at January 23, 2004 07:51 AM