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September 17, 2004

College Admissions; Hormesis-- A Little Poison Strengthens You

At the Law and Econ Lunch yesterday, we were discussing how hard it is to get data. I'd asked if anybody knew of evidence as to how whether if two college applicants appeared with identical high school records, we would expect the student from a poor family to do better in college than the one from a rich family. Admissions offices have the data to find this out, but they are secretive. Have they done the studies themselves? We speculated as to whether they had the expertise. Professor Stake is an expert on these things, having done more than anyone to figure out how US News rankings of law schools works and having authored "The Ranking Game" website. He thought it quite possible the studies hadn't been done, and knows from experience that it is hard for even quasi-insiders (e.g., the chairman of a faculty admissions committee) to get the data.

At any rate, Dr. Stephen Peck, a first-timer who is visiting SPEA for the year, brought up his difficulties in getting health data from the nuclear power industry. He'd wanted to study cancer incidence at low levels of radiation, but couldn't get the data. That made me think about hormesis-- the idea that often low levels of poison seem to increase health rather than reduce it. He would have had a good test of it, and, indeed, some studies conclude that low levels of radiation reduce cancer rates. Whether the studies are right is a different matter-- one oughtn't to trust that kind of study without seeing what they actually did, since epidemiological estimates, even ones published in reputable journals, are often quite worthless because they so often omit relevant variables....

So I googled "hormesis", mainly for future reference. "An Introduction to Radiation Hormesis", by S. M. Javad Mortazavi is poorly written but has good content:

It is a general belief that low doses of ionizing radiation produce detrimental effects proportional to the effects produced by high-level radiation. Over the past decades, however, some pioneer scientists reported that low-dose ionizing radiation is not only a harmless agent but often has a beneficial or hormetic effect. That is, low-level ionizing radiation may be an essential trace energy for life, analogous to essential trace elements. It has been even suggested that about one third of all cancer deaths are preventable by increasing our low dose radiation.

...

In the early 1940s C. Southam and his coworker J. Erlish found that despite the fact that high concentrations of Oak bark extract inhibited fungi growth, low doses of this agent stimulated fungi growth. They modified Starling's word "hormone to "hormesis" to describe stimulation induced by low doses of agents which are harmful or even lethal at high doses. They published their findings regarding the new term "hormesis" in 1943 (Bruce M. 1987).

...

In 1927 Herman J. Muller,a Nobel Prize winner, found that X-rays are mutagen and there is a linear relationship between mutation rate and dose.
...

According to UNSCEAR report (1994), among A-bomb survivors from Hiroshima and Nagasaki who received doses lower than 200 mSv, there was no increase in the number of total cancer death. Mortality caused by leukemia was even lower in this population at doses below 100 mSv than age-matched control cohorts.

...

Although still we do not know the entire mechanisms of radiation hormesis, the following theories may explain this process:

1- D...NA repair (Mollecular level)
According to this theory, low doses of ionizing radiation induce the production of special proteins, that are involved in DNA repair processes (Ikushima 1996). ...

2- Free radical detoxification (Molecular level)
In 1987 Feinendengen and his co-workers indicated that low doses of ionizing radiation cause a temporary inhibition in DNA synthesis (the maximum inhibitionat 5 hours after irradiation). This temporary inhibition of DNA synthesis would provide a longer time for irradiated cells to recover (Feinendengen et al. 1987). This inhibition also may induce the production of free radical scavengers, so irradiated cells would be more resistant to any further exposures.

3- Stimulation of immune system (Cellular level)
Despite the fact that high doses of ionizing radiation are immunosupressive, many studies have indicated that low doses radiation may stimulate the function of the immune system. In 1909 Russ first showed that mice treated with low-level radiation were more resistant against bacterial disease (Russ VK 1909).

Another article is "Nietzsche's Toxicology: Whatever doesn't kill you might make you stronger" (Scientific American, 2003)

This idea may sound bizarre, but such adaptation to stress is common, says physiologist Suresh Rattan of Århus University in Denmark. Exercise, for instance, plays biochemical havoc with the body : starving some cells of oxygen and glucose, flooding others with oxidants, and depressing immune functions. "At first glance, there is nothing good for the body about exercise," he notes.

...

The definitive rat study that linked high doses of dioxin to cancer, published in 1978 by Richard Kociba of Dow Chemical and his colleagues, also found that low doses reduced the incidence of tumors.

Finally, see "Radiation Hormesis"

Posted by erasmuse at September 17, 2004 04:27 PM

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