[ RadSafe ] heavy metal hormesis

[Jaro]

Jerry,

Here's a few excerpts that address, in a general way, your query re. heavy
metals.....

 Jaro
^^^^^^^^^^^^^^^^^^^^^



http://www.insightmag.com/news/2004/01/06/National/Can.Toxins.Lead.To.Health
ier.L.shtml
Can Toxins Lead to Healthier Lives?
By John Pike
<SNIP>

"I believe there is not a single chemical that does not" exhibit patterns of
hormesis, Calabrese says. It is a general response that is shown with
mercury, lead, components of cigarette smoke, cadmium, marijuana, cocaine,
alcohol and "everything that is regulated by the EPA."
<SNIP>


DISCOVER MAGAZINE By Will Hively December 2002 pages 76 80
Is Radiation Good for You ? Or dioxin? Or arsenic?
The answer is yes but only in very small doses, says one of the country's
most respected toxicologists.
If he's right, environmental regulation will never be the same
<SNIP>

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."

Unfortunately; benefits from hormesis may be practically impossible to
harness. Hormesis usually occurs at doses about five times lower than the
toxic threshold, Calabrese has found. The EPA often sets acceptable exposure
limits 20 times lower than that. But sensitivities can vary from individual
to individual by a factor of 10 to 100. A dose that stimulates hormesis in
one person may well be toxic to another. That variability is a major reason
why hormesis won't add new medicines to our cabinets anytime soon.
<SNIP>
============

http://www.nature.com/cgi-bin/doifinder.pl?URL=/doifinder/10.1038/421691a
Calabrese, E.J. & Baldwin, L.A. Toxicology rethinks its central belief.
Nature, 421, 691-321, (2003)

Dangerous levels of toxins miscalculated
Potential pollutants and poisons may be beneficial in low doses.
13 February 2003
HELEN R PILCHER
We may be putting too much effort into cleaning our environments.

The levels at which potentially toxic substances such as mercury and lead
are classified as dangerous may have been miscalculated, two US scientists
are warning. Risk assessments and regulations on safe limits for these
substances in medicine and the environment may have to be rethought, they
warn.

There are safe levels below which potential pollutants and poisons may
actually be beneficial, say Edward Calabrese and Linda Baldwin of the
University of Massachusetts in Amherst. For the past 30 years,
cancer-causing chemicals and X-rays have been viewed largely as dangerous
whatever their level.

"The field of toxicology has made a terrible blunder," says Calabrese. "A
lot of high-powered people need to take the time to explore this."

For example, dioxins, which are industrial by-products that at certain doses
can cause cancer, can actually reduce tumour growth in some species.
Similarly, small amounts of the toxic trace metal cadmium can promote plant
growth.

"What we call 'toxic chemicals' is a misnomer," says cell biologist and UK
government advisor Anthony Trewavas from Edinburgh University. "Mild
chemical stress is beneficial."

Having identified over 5,000 similar examples, Calabrese and Baldwin are
among a growing number of researchers who feel that the hazardous nature of
toxic substances has been overstated. The levels used in studies are not
comparable to those normally experienced by humans, Calabrese says. "This
provides an interesting challenge for the clinical and pharmaceutical
industries as they develop new medicines."

The point of toxicological testing is to determine the drug exposure at
which undesired effects are observed

UK Medicines Control Agency

Britain's Medicines Control Agency (MCA) is more cautious. "The point of
toxicological testing is to determine the drug exposure at which undesired
effects are observed," a spokesperson said, adding that the new criticisms
are, "unlikely to change the way in which the MCA or other regulatory
agencies conduct product risk-benefit analysis."

The debate also raises the question of how clean our environment really
needs to be. Some argue that billions of dollars are being wasted ridding
the world of substances that are dubbed 'hazardous', when low levels could
actually be a good thing.

"We don't need to spend large amounts of money on removing chemicals from
the environment," says Trewavas. "Food contains lots of natural chemicals
that are as damaging as synthetics. We consume lots of these all the time
without harm. The public need re-educating in this."

But convincing people that 'safest' is a more meaningful description of risk
than 'safe' and 'dangerous' is notoriously difficult.
=================




-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl]On
Behalf Of jjcohen
Sent: Sunday, May 08, 2005 2:40 PM
To: James Salsman; radsafe at radlab.nl; jimm at wpi.edu
Subject: Re: [ RadSafe ] heavy metal hormesis


Hormesis can be considered a general rule in nature, but not a
universal rule  since there are exceptions. For example,
 3 heavy metals that show no evidence of hormesis
are lead, cadmium, and mercury. If anyone has contrary
information, I would like to see it.    Jerry Cohen


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