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From: "Jorge Bonilla" <yoyo...@msn.com> - Find messages by this author

Date: 10 Feb 2005 12:10:28 -0800
Local: Thurs, Feb 10 2005 12:10 pm
Subject: Re: Low Level Of Mercury Exposure
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jdrew63...@aol.com wrote:

What does number seven have to do with the rest of your post? This is a

study on microleakage (microleakage of liquids and bacteria through the

space between dentin and amalgam, not the release of Hg from the
amalgam).
Dr. Bonilla

Hmmm, doc, are you desperate to pick out the things you can pick at,
rather than read the entire post?

Research in molecular biology has elucidated mechanisms that may
underlie the
toxic effects of mercury.

Studies of the effects of mercury on the immune system in rodents have
enhanced
knowledge of the mechanisms whereby mercury affects the immune system.
Clinical
studies of occupationally exposed employees have objectively confirmed
subclinical influence of mercury on the immune system at low levels of
mercury
exposure.

The thyroid has been identified as the target organ for the toxic
effect of
mercury in occupational exposure to mercury vapour in low doses.

Clinical studies of the effects of mercury on occupationally exposed
workers,
using modern diagnostic methods, have elucidated the connection between

dose
and effect. They have also identified and quantified neuropsychological

symptoms at low exposure levels.

Relation between symptoms and mercury concentrations in saliva after
chewing.
The Tbingen amalgam study could establish in the especially examined
group of
21-40 year old persons a statistically significant relation between
mercury
levels in saliva and symptoms. Only symptoms which are characteristic
of
subacute or chronic mercury exposure in the low-level range were
studied.

Low-level chronic exposures to mercury may affect the peripheral
nervous system
resulting in polyneuropathies (reduced sensory and motor nerve
function) and
neuropsychological effects (visual alterations, sensory loss, stress)
(ATSDR
1989); these effects correlate to tissue levels of 20 to 40 g/g.
Neuropsychological effects were also reported by Smith et al. (1970)
for
occupational exposure to mercury levels of > 0.1 mg/m3. Mercury
concentrations
below this value did not appear to cause observable effects. Kishi et
al.
(1993) reported that neurobehavioral and motor function effects
persisted in
ex-mercury miners more than 10 years after cessation of exposure.

Once inhaled, elemental mercury is mostly converted to an inorganic
divalent or
mercuric form by catalase in the red blood cells. This inorganic form
has
similar properties to organic mercury. Small amounts of non-oxidized
elemental
mercury continue to persist and account for CNS toxicity.

Elemental mercury, as a vapor, which escapes from fillings, penetrates
the
blood-brain-barrier and enters the CNS, where it's ionized and trapped,

attributing to its significant toxic effects

http://www.floridalcv.org/FLCVEdFund/environmental_effect_of_dental_a...

Environmental Effect of Dental Amalgam

Mercury is one of the most toxic substances commonly encountered, and
according
to Government agencies causes adverse health effects in large numbers
of people
in the U.S.[1]  The extreme toxicity of mercury can be seen from
documented
effects on wildlife by very low levels of mercury exposure. The average

amalgam
filling has more than  gram of mercury, and has been documented to
continuously leak mercury into the body of those with amalgam fillings
due to
the low mercury vapor pressure and galvanic current induced by mixed
metals in
the mouth.

1.  Hg plasma concentration correlated with no.of amalgam fillings.
http://tinyurl.com/cdb0  2003

2.  Correlation between number of fillings and salivary Hg.
http://tinyurl.com/cgs  2000

3. The amount of organic and inorganic mercury in paraffin-stimulated
saliva
was significantly higher in subjects with dental amalgam fillings
http://tinyurl.com/cgs1 2001
4.  Mercury vapour release increases with chewing,  with absorption and

uptake
by the brain and kidneys. http://tinyurl.com/cczd 2002

5.  Amalgam causes nerve cell toxicity in culture.
http://tinyurl.com/ccyo
2003

6.  Plasma concentrations of mercury before and after treatment
supported the
metal exposure to be causative for the ill health.
http://tinyurl.com/ccyr
2002

7  None of the materials tested consistently prevented microleakage.
http://tinyurl.com/cfcg  2002

8.  In neither of the nonamalgam groups was this [wastewater] limit
exceeded,
but 20.5% in the amalgam group exceeded the limit
http://tinyurl.com/ccyu 2002

9.  I-Hg levels in placenta increased with an increasing number of
maternal
dental amalgam fillings (p < 0.001)... a substantial fraction of
maternal blood
I-Hg, probably as Hg(0), reached the fetus. http://tinyurl.com/cgrz
2002

10  Evidence of a pro-oxidant role of the amalgam Hg chronically
released in
saliva. http://tinyurl.com/cgrv  2002
11. Mercury released into air from dry abraded amalgam was shown to be
above
the recommended industrial limit http://tinyurl.com/cf7j  2002

http://www.chem-tox.com/pregnancy/mercury.htm

Low Level Mercury Causes Behavior Problems During Pregnancy

Subtle behavior problems were observed in mice offspring exposed to a
single
low level mercury dose.

In summarizing the results of their study, the researchers stated,

"This hypothesis generating study showed highly significant
correlations
between mood scores and most measures of low level Hg (mercury)
exposure. The
specific mood measures most associated with Hg exposure were tension,
fatigue,
and confusion. The strength of these associations suggests that mood
should be
included for investigation in future hypothesis-testing studies.....
Among the
cognitive and motor function tests, only the digit span and simple
reaction
time (nondominant hand) scores were associated with any measure of
exposure...... Overall, and despite the small size of the study
population,
this investigation found some evidence of adverse preclinical effects
at
mercury doses averaging 36 ugs/l in urine. The mood and symptom results

of this
study agree with prior evaluations of both high and low urinary mercury

doses.
These preliminary survey findings support a critical evaluation of the
adequacy
of the 50 ug/g creatinine biologic threshold for mercury proposed by
the World
Health Organization This is the first U.S. dental study to detect
potential
behavioral deficits at such a low level of exposure. A larger and more
comprehensive study is required to accurately determine a biologic
threshold of
adverse central and peripheral nervous system effects for elemental
mercury."

Drs. Diana Echeverria, Nicholas J. Heyer, Michael D. Martin, Conrad A
Naleway
Depart. of Environ. Health, Univ. of Washington, School of Dentistry,
Univ. of
Washington Neurotoxicology and Teratology, Vol. 17(2):161-168, 1995

Dopamine Uptake in Brain Cells Changed By Methylmercury

Attention Deficit Disorder children were reported in other headings in
this
book as having altered dopamine levels. Several compounds, including
alcohol,
have been shown to alter dopamine levels in test animals. Now,
researchers at
Duke University Medical School have shown that even very low levels of
methylmercury result in dopamine and norepinephrine brain
neurotransmitter
changes.