case report cited an incident wherein four adults were acutely exposed to
mercury vapor resulting from the smelting of dental amalgams (Taueg et al.
1991). Initial signs of toxicity included nausea, diarrhea, dyspnea, and
chest pains. Despite chelation therapy, all four patients died 11 to 24 days
after initial exposure. Mercury concentrations in the house were as high as
912 ?g/m3 at or within 11 to 188 days after the exposure, and postmortem
blood mercury levels ranged from 58 to 369 ?g/L. Historically, the triad of
increased excitability, tremors, and gingivitis has been recognized as
characteristic for mercury poisoning (Goyer 1991).

  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.

Mercury vapor from dental amalgams has been identified as a major source of
exposure to inorganic mercury in the general population (WHO 1991). An
average mercury dose from dental amalgams has been estimated to be only 4 to
5 ?g (Halbach 1995).

1. Central nervous system and kidneys: Both the central nervous system and
kidneys are affected by inorganic mercury. The toxic effects may occur with
acute, subchronic, or chronic exposure depending on the exposure level and
the resulting body burden of mercury. Animal data suggest that the renal
effects may be immunologically mediated. The central nervous system,
especially during prenatal and postnatal development, is the primary target
organ for methyl mercury.

3.4.2.1. Primary Target Organ(s)1. Central nervous system and peripheral
nervous system: The critical target organs for inhalation exposure to
elemental mercury vapor are the central nervous system and the peripheral
nervous system.

Elemental mercury is found in liquid form, which easily vaporizes at room
temperature and is well absorbed through inhalation. Its lipid (fat)-soluble
property allows for easy passage through the alveoli into the bloodstream
and red blood cells. 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. It is not well
absorbed by the GI tract and, when ingested, is only mildly toxic. Inorganic
mercury is highly toxic and corrosive and is the most destructive form, but
its destruction is limited to where it's located. It doesn't have the
ability to move through tissues like other forms. It gains access orally or
dermally and is absorbed at a rate of 10% of that ingested. It has a
nonuniform mode of distribution, secondary to poor fat solubility, and
accumulates mostly in the kidney, causing renal damage

Millions of U.S. citizens are being exposed to mercury levels that exceed
established health standards. Occupational exposure to mercury is a hazard
for dental personnel. The only defense for its use comes from the total
support of organized dentistry. Science, in over 12,000 scientific studies,
has not been able to determine one constructive purpose served by the
presence of this toxic metal in the human body. No amount of exposure to
mercury vapor can be considered harmless. Once it has leached from the
dental fillings and infiltrated the body, mercury becomes a neurotoxin.
Mercury is more neurotoxic than arsenic and far more neurotoxic than lead.
Mercury has been used quite extensively by the medical profession in
anti-fungal preparations, diuretics, antiseptics, brain scans (radioactive
mercury), etc. Merthiolate and Mercurochrome, which were very common
"first-aid" items in most households and are still used extensively in
hospitals, contain mercury.
Nerve endings in the peripheral nervous system constantly scan their
environment, engulfing foreign particles and bringing them across the cell
membrane for inspection. These substances may then travel all the way up
from the foot to the spinal cord to be presented to the nerve cells there.
As it travels up the axon, mercury destroys a substance called tubulin, used
as insulation for neurofibrils in the microtubules, effectively destroying
the nerves. Within 24 hours of injecting a minute dose of mercury into a
muscle anywhere in the body of test animals, it is detectable in the spinal
cord and brain. The mercury is also found in the kidneys, lungs,
bloodstream, connective tissue, adrenals and other endocrine glands. In the
brain, it tends to congregate in the hypothalamus, which regulates the
autonomic nervous system, and in the limbic system, believed to be the seat
of emotions.
The most devastating effect of mercury in the nervous system is that it
interferes with energy production inside each cell. Nerve cells are impaired
in their ability to detoxify and nurture themselves. The cell becomes toxic
and dies, or lives in a state of chronic malnutrition. It is common for
heavy metals to migrate to and acumulate in nerve ganglia (nerve relay
stations). As a heavy metal (which means heavier than water), mercury tends
to accumulate in the lowest parts of the body, such as the floor of the
mouth, the pelvic floor, and the feet. Pelvic symptoms, in both men and
women, are very commonly caused by metal toxicity of the Frankenhauser's
ganglion. This can account for premature ejaculaton and an enlarged prostate
in men, and endometriosis, pelvic pain, and hormonal dysfunction in women.
Neural therapy cleans up this area through the painless injection of the
Frankenhauser's ganglion (just above the pubic bone) with a local
anesthetic. This opens up most of the ionic channels in the cell wall; the
cell is then able to excrete much of its toxic components. This spurs the
body to dump large amounts of mercury into the urine.

A dentist can't legally throw amalgam material or extracted amalgam filled
teeth in the trash, bury them in the ground, or put them in a landfill, but
the ADA and the EPA say it's okay to put it in people's mouths. In 1976, the
U.S. Congress requested that the FDA "classify" dental amalgam fillings. The
Federal Register recorded another such request in 1980. Multiple requests
have been made over the years, yet there is still no classification of
dental amalgam. The FDA has steadily refused to classify amalgam. The
government agencies have been defending the use of mercury. Consider for a
moment the national consequences if mercury in fillings were reported to be
dangerous. The offending parties (dentists, the ADA, dental manufacturers
and distributors), if found guilty, would be liable.

Mercury Vapor

Silver mercury fillings are not stable. These fillings emit mercury vapor at
a rate of 2.8 micrograms per cubic meter of air breathed in the resting
state, and their emission rate accelerates dramatically (as high as 49 mgs)
after minimal mechanical, chemical, and temperature stimulations. It is also
very volatile. This means that "metallic" mercury gives off mercury vapor
when agitated, compressed or exposed to increases in temperature. Mercury
vapor--which is colorless, tasteless and odorless--if inhaled into the
lungs, passes into your bloodstream for distribution to all body tissues. It
is at this point that biotransformation begins. Some of the mercury vapor
remains unchanged, and some of it is oxidized. (This means to remove a pair
of hydrogen atoms and to combine with oxygen. Chemically it means the
increase of a positive electrical charge and the decrease of the negative
charge, which in effect ionizes the vapor). The unchanged portion exists
dissolved in the blood lipids (fats). The toxic effects are produced by that
portion that is oxidized into mercuric ions which occurs partly in the
blood, partly in the tissues but mainly in the red blood cells.
Several researchers, beginning with Jernelov in 1969, have demonstrated the
microbial conversion or methylation of mercury by various microorganisms.
This was demonstrated in the laboratory as well as inside the bodies of
animals. In 1975, Edwards and McBride demonstrated the methylation of
mercuric chloride in human feces. It was also in 1975 that Rowland, Grasso
and Davies determined that most strains of staphylococci, streptococci,
yeasts and escherichia coli found in the human intestine (these are bacteria
and yeasts of different forms and shapes that are normally present in the
human gut) were capable of methylating mercury. It was in 1983 that Heintze
and his associates made the startling discovery that saliva can also
methylate mercury being released from the amalgam fillings.
Confirmation of the escape of mercury vapor and ions from amalgam dental
fillings is provided by The World Health Organization (WHO) Environmental
Health Criteria 118 document (EHC 118) on inorganic mercury. It clearly
states that the largest estimated average daily intake and retention of
mercury and mercury compounds in the general population, is from dental
amalgams, not from food or air. Mercury vapor inhaled into the lungs is
absorbed almost 100 percent and immediately passes into the bloodstream. It
takes approximately four minutes before mercury is converted or oxidized
into an ionic state from its elemental vapor state. While in its elemental
form, mercury vapor is lipid (fat) soluble and readily passes through the
blood-brain barrier or the placental membrane.
It can also accumulate in other organs and tissues of the body. The
estimated average daily intake of mercury from dental amalgams is 3.8 - 21
micrograms per day. Two-thirds of the body burden of mercury is derived from
the mercury vapor released from amalgams. The static, unstimulated release
of mercury vapor from amalgam fillings, which goes on 24 hours a day, 365
days a year, is a major contributor to total mercury body burden. Large
amounts of mercury vapor are released during chewing. After only ten minutes
of gum chewing, there is an average increase in mercury release of 15.6
times more than during the resting state in test subjects. That converts to
a 1,560% increase in mercury release."The World Health Organization has
calculated that the average human daily dose of mercury from various sources
are: Dental amalgam = 3.0-17.0 mg/day (Hg vapor) Fish and Seafood = 2.3
mg/day (methylmercury) Other food = 0.3 mg/day(inorganic Hg) Air & Water =
Negligible traces (NOTE mg = Micrograms)" (World Health Organization
Figures, from Environmental Health Criteria 118: Inorganic Mercury, Geneva,
1991. These figures confirm Amalgam as #1 average source for Environmental
Mercury exposure.)"You wouldn't take a leaky thermometer, put it in your
mouth, and leave it there 24 hours a day, 365 days a year. Yet that's
exactly what happens when an amalgam filling is installed in your
mouth."--Dr Michael Ziff.Mercury Vapor AnalyzerThe <I
style="mso-bidi-font-style: normal">Jerome 431-X Mercury Vapor Analyzer uses
a patented gold film sensor for the detection and measurement of toxic
mercury vapor in the air, including the air in your mouth. It is a portable
hand-held unit, weighing only seven pounds that can easily be carried to
locations where there is a concern about mercury. It is the same unit used
for chemical toxicology testing by OSHA and the EPA to monitor industrial
hygiene, mercury spill cleanups and mercury exclusion testing. It is also
suitable for monitoring mercury concentrations in a dental office during a
daily routine.The simple push-button operation allows users to measure
mercury levels in just seconds. The detection range is from 0.000 to 0.999
mg/m3 Hg. The gold film sensor is inherently stable and selective to
mercury, eliminating interference common to ultraviolet analyzers, such as
water vapor and hydrocarbons. When the sample cycle is activated, the
internal pump in the 431-X draws a precise volume of air over the sensor.
Mercury in the sample is adsorbed and integrated by the sensor, registering
it as proportional change in electrical resistance. The instrument computes
the concentration of mercury in milligrams or nanograms per cubic meter, and
displays the final result in the LCD readout.The 431-X includes features not
available in older Jerome models. When attached to either a data logger or
computer, the analyzer automatically regenerates the sensor when it becomes
saturated and then resumes sampling. An improved film regeneration circuit
makes the sensor last even longer. It can operate up to six hours on a fully
charged nickel-cadmium battery.This analyzer can easily be used to measure
mercury vapor concentration on a patient before and after chewing a piece of
gum for 5 minutes. Chewing, or tooth grinding, increases the heat between
teeth and, thus, enhances the release of mercury from amalgams.This is an
insightful eye-opener for those skeptical dentists who still refute the
possibility of mercury leaking out of dental amalgams and their own health
and their patients' health being in jeopardy by their refusal to acknowledge
something that is clearly visible with this machine.Some reported
measurements of dental patients' oral mercury vapor have been twice the OSHA
standard of 50 ?g/cubic meters which would place them in violation of the
OSHA standard based on an employee's 8-hour work exposure for a 40-hour work
period seven days a week. Once measurements are taken, you will realize that
the most toxic spaces may not be at one of the EPA's superfund sites, but
simply right under your nose.

Mercury Ingestion

Mercury readily mixes with food and is swallowed with it. The body uptake
from inorganic mercury, swallowed with saliva, can be as much as hundreds of
micrograms per day for individuals with a large number of amalgam fillings.
Urinary excretion is a common indicator of mercury toxicity, even though
fecal excretion of mercury is twenty times greater than the corresponding
urinary excretion. There is a statistical correlation between the mercury
concentration in saliva and the number of amalgam fillings. The United
States government has determined and ruled that the continual exposure to
mercury from amalgam fillings is not without risk to patients. We are
concerned over picograms and micrograms of mercury in apples and are looking
the other way when milligrams, one million times more, are being implanted
directly into a child's mouth. There is a phenomenon that occurs in the
mouth that can contribute to the release of mercury, and is called
corrosion. Corrosion is similar to "rust" and means that surface particles
of the filling material are being chemically broken down and released into
the oral cavity.

Mercury vapor is released when you chew or grind. Additionally, minute
rusted particles of the amalgam are being abraded and taken up by your food
or saliva and swallowed. Intestinal enzymes and bacteria both produce
methylmercury, an even more toxic form than elemental mercury, may act upon
these minute particles of mercury filling. Although several sources
contributing to the domestic mercury concentrations have been identified,
human wastes (feces and urine) from individuals with dental amalgam fillings
are believed to be the most significant source--greater than 80 percent.
Conventional amalgam was routinely placed until 1976, when the new
state-of-the-art amalgams (50% mercury and 30% copper) were introduced. They
emit up to 50 times more mercury than the earlier, conventional amalgam
fillings. That means that every new high-copper amalgam filling placed today
has the effective toxic equivalent of fifty of the older amalgam fillings.
If other fillings are in the mouth, such as gold crowns, nickel crowns, and
removable bridges or braces, the mercury emission further increases from the
amalgam. This is due to the electrical current generated by the presence of
dissimilar metals in an electrolyte such as saliva. Heat will reliably
increase the rate of escape of mercury vapor from amalgam fillings. Vapor
detectors, held above amalgams, revealed an increase from 3 micrograms to
over 500 micrograms ten seconds after a hot drink was swallowed."Worldwide
there are over 4000 research papers indicating mercury is a highly toxic
substance. How can dentists be so thoughtless as to place one of the
deadliest toxins in existence *two* inches from our brain?"--Tom Warren"The
mercury uptake from amalgam is the dominating source for inorganic mercury
in the central nervous system and is the major source of total mercury
uptake in the population."--Maths Berlin, a leading Swedish toxicologist

Blood-Brain Barrier

The blood-brain barrier is a normal mechanism that is supposed to restrict
the entry of substances into the brain. The transfer of substances such as
nutrients, waste products, oxygen and carbon dioxide, hormones, and poisons
in and out of the cells of the body is accomplished through the smallest of
blood vessels, the capillaries. The capillaries of the brain have a special
structural design to provide extra protection for the critical brain cells.
Unlike capillaries elsewhere in the body, the cells lining the brain
capillaries are overlapped and less porous. This special structure prevents
many substances from passing into or out of the brain that would easily pass
to and from other body cells.
Substances that can dissolve in fats readily penetrate the membranes of
cells, as these membranes have large amounts of fat-containing molecules.
Elemental mercury vapor and methylmercury are fat-soluble and therefore
easily penetrate cell membranes, including those of the placenta and the
blood-brain barrier. This barrier does, however, selectively allow passage
of certain smaller water-soluble substances necessary to the brain, such as
glucose and essential amino acids. Mercury vapor has no electrical charge
(non-ionic) and is fat-soluble, which accounts for its extremely potent
toxicity in the elemental vapor form. The oxidation of mercury vapor occurs
in the blood and in the body cells. Ionic mercury is the harmful form of
mercury because it is chemically active and can readily combine with
tissues, exerting its toxic influence in that manner.
Elemental mercury vapor, after entering the bloodstream, is oxidized through
the mercurous into the mercuric ion. These reactions requires several
minutes for completion; because of this delay, elemental mercury stays in
the blood long enough to reach all tissues and organs. In its elemental
form, mercury easily penetrates the blood-brain barrier and infiltrates
nerve cells, where final oxidation proceeds. By easily overcoming the
blood-brain and placental barriers, elemental mercury is particularly
dangerous during long-term or chronic exposures, representing a potentially
serious hazard in many occupations. Once mercury has penetrated the
blood-brain barrier, its oxidation to the ionic form is completed. This
ionic mercury now has an electrical charge and is no longer fat-soluble.
Ionic mercury is very active chemically and readily combines with body
substances, thereby exerting its toxic effect.

This ionic mercury can no longer easily penetrate the blood-brain barrier
and is very resistant to removal from the brain. Mercury is retained in
brain tissue for extremely long periods of time. Autopsy studies have
demonstrated a definite correlation between levels of mercury found in the
brain and the number and surfaces of dental amalgam fillings present. When
mercury ions are absorbed into the bloodstream, even in minute amounts (less
than 1.0 parts per million), they are capable of impairing the blood-brain
system within 4-6 hours, allowing passage of normally barred plasma solutes
into the brain from the blood, that otherwise would be denied entry. Mercury
will not only damage the brain but it will also increase exposure of the
brain to other harmful substances in the blood. The blood-brain barrier is
also an active site for the regulation of the uptake of metabolites from the
blood to the nervous system.
The impairment of the blood-brain barrier, together with the possible
inhibition of certain associated enzymes by the mercury, is probably
responsible for the great reduction of the uptake of amino acids and other
metabolites by the nervous system after mercury administration. Amino acids
are the building blocks of proteins which are the structural materials used
to construct the cells of the body, along with physiological materials such
as enzymes and hormones. There is no scientific evidence that brain cells
can be regenerated. This is why mercury damage to the brain is permanent and
irreversible. Since mercury vapor readily traverses the placental membrane,
the oxidation of mercury vapor in the fetal blood or at the fetal
blood-brain barrier itself no doubt results in damage to the fetal
blood-brain barrier. But the damage to the fetal blood-brain barrier may be
even more important, preventing the uptake of vital amino acids for the
construction of the irreplaceable brain cells.
There is absolutely no doubt that exposure to methylmercury in pregnant
women presents a serious threat to the fetus. A number of studies have
described the effects on infants of prenatal exposure to methylmercury,
while the exposed pregnant mothers exhibited little or no observable signs
or symptoms from exposure. The neurological effects on these infants were as
severe as cerebral palsy and even death, but less easily recognizable
symptoms were more common, such as delayed mental development, delayed
speech development, delayed motor development, and learning deficits. The
major influence of mercury vapor on the fetus is not the promotion of birth
defects; but rather the toxic effect on the body cells, particularly those
of the brain. In spite of the wealth of information strongly demonstrating
the potential risk of elemental mercury vapor to the unborn child, the
scientific community has not yet seen fit to responsibly investigate this
awesome question."It is sobering to realize that the original "quacks" were
dentists who advocated the use of mercury amalgam and that most dentists are
still advocating it today."---"The maximum amount of mercury that the
Environment Protection Agency allows people to be exposed to is 5,000 times
smaller than the permissible amount of lead exposure; in other words the EPA
apparently considers mercury to be 5,000 times more toxic than
lead."--Marcia Basciano DDS

Fertility

Mercury has been shown to pass the placental membrane in pregnant women and
cause permanent damage to the brain of a developing baby. A special
relationship regarding mercury distribution exists between the mother and
the fetus. Much higher levels of methylmercury have been reported in cord
blood versus that contained in maternal blood. In animal experiments it has
also been shown that there is a much higher accumulation of mercury in the
fetal brain tissue than in the maternal brain tissue. Mercury exposure leads
to hormone and immune disturbances that can reduce fertility. Reduced
fertility among dental assistants with occupational exposure to mercury is a
common problem. Many of the female fertility cycle events are related to
posterior pituitary activity, so amalgam is another factor that can disturb
fertility as well as functions unrelated to pregnancy. Estrogen function can
also be influenced by amalgam. Blood serum phosphorus is a guideline to
endocrine balance. If the phosphorus is below 3.5 mg%, there is an endocrine
disturbance, somewhat related to the degree of drop below 3.5. The most
effective hormones in balancing the phosphorus level are the sex hormones.
All males and all females produce both estrogen and testosterone. The males
produce more testosterone and the females more estrogen, but there is a
balance between the two in both sexes. Small doses of both hormones are used
in both sexes to balance the serum phosphorus.

The menstrual and reproductive cycles are controlled by a very complex
feedback mechanism between the ovaries, hypothalamus, and the pituitary. In
the case of follicle stimulating hormone (FSH), there is a negative feedback
relationship with estradiol at all times. When estrogen levels are low, the
release of leutinizing hormone (LH) is increased, and when estrogen levels
are high, LH is decreased. This ebb and flow controls the hormonal function
leading to ovulation and the mid-cycle surge of both LH and FSH and the
reduction of LH and FSH at the luteal phase relate to a feedback
relationship with progesterone. Progesterone is not secreted by the ovary
until just before ovulation. This, in turn, provokes ovulation--progesterone
secretion, which undergoes a tremendous increase. The high levels of
progesterone and estrogen associated with the luteal phase combine to
suppress FSH and LH during the corpus luteum phase. Mercury inhibits release
of FSH from the pituitary by damaging membranes of cells in the anterior
pituitary.
Chronic inhalation of mercury vapor from amalgam fillings for twenty years
or more can result in accumulation of pathologic quantities of mercury in
the brain and other critical organs and tissues. Human autopsy studies of
accident victims have shown a positive correlation between the numbers of
mercury amalgam dental fillings and the concentration of mercury in the
brain. The onset of clinically observable signs or symptoms of mercury
toxicity may take as long as 20-30 years to appear, depending on a person's
biochemical individuality. Lubricated condoms and birth control creams or
gels have mercury as the primary spermicide. It is not required that the
word mercury appear on the label, as it is assumed that everyone knows
mercury is in there. The uterus is a collection center for mercury. Hal
Huggins reported that more than 90% of the imbalances, created by sex
hormone disturbances were corrected within a few weeks of amalgam removal.
His patients noted differences in fertility, less pain during periods,
relief from endometriosis, and a trend toward optimization of the days of
menstrual flow. PMS is one of the most common symptoms to change after
amalgam removal. Amenorrhea, or the complete absence of a menstrual flow,
responds to amalgam removal. This is usually in women in their twenties or
thirties. Even in women who have gone through a sort of premature menopause
in their early forties, the periods may start up again for a couple of
years. This has resulted in surprise pregnancies. Women should avoid
pregnancy for at least six months after amalgam removal.

The Placenta

The circulatory systems of the mother and fetus are separated by a very thin
membrane in the placenta. The purpose of this membrane is to ensure that
there is no actual mixing of maternal blood with the fetal blood. This
placental membrane was formerly called the placental barrier. Its function
was assumed to be one of protecting the fetus from possible damage from any
of the potentially toxic drugs or substances that might be present in the
mother's blood. The Thalidomide disaster in 1961 demonstrated that the
passage of toxic substances from mother to fetus did occur and could result
in tragic birth defects and deformities. Mercury reduces the blood's ability
to carry oxygen and, although fetal blood flow might be normal, the reduced
oxygen content of the blood would parallel the hypoxic condition. Mercury
may affect the balance or status of most of the body's essential nutrients.
No scientific study has ever addressed the relationship between chronic
mercury exposure and placental weight/birth weight. From the time of
fertilization until birth, the offspring is dependent upon maternal sources
for all nutrition.
There are four major areas that are considered to be critical or
determinants in the outcome of fetal development: (1) the mother's
nutritional status, (2) the structural and functional quality of the
placenta, (3) the genetic makeup of the offspring, and (4) the presence of
physical, chemical, or mechanical insults to mother and child during
pregnancy. Mercury can also affect the satisfactory outcome of fetal
development in all four of these areas.
A possibly contributory factor in cadmium and mercury fetotoxicity may be an
effect on the transmembrane transport of nutrients, such as amino acids,
across the placenta to the fetus. An inhibition of nutrient transport may
cause fetal death, congenital malformations, or growth retardation. The
toxic effects of cadmium and mercury may be found in the placenta where
presence of these metals prevent the passage of required nutrients to the
embryo/fetus. The placental membrane will stop many substances. However, it
is made of fat molecules, and mercury vapor and methylmercury, being
fat-soluble, will penetrate the membrane. The lack of knowledge concerning
the mechanisms of mercury toxicity as they relate to the human reproductive
cycle is compounded by the scarcity of scientific studies investigating the
effects of mercury vapor. The majority of scientific studies on mercury have
dealt with methylmercury or inorganic mercury. Very little attention has
been paid to the threat posed by low-level chronic exposures to toxic
metals.
A great deal of the available scientific data was derived from observation
of acute exposures where a large single injection of the toxic metal being
investigated was administered and the results examined. While there is no
barrier preventing the transfer of mercury, there is a slight barrier to the
transfer of lead, and the greatest barrier is to the transfer of cadmium.
Mercury vapor enters the body and its cells far more readily than most other
forms of mercury. Researchers have found that the placental transfer of
mercury varies with the chemical form of mercury; that is, methylmercury is
more readily transferable than mercuric nitrate.
The mercury concentrations in the placenta and the infant's hair are
directly related to the infant's body burden of mercury

Mercury Vapor

Silver mercury fillings are not stable. These fillings emit mercury vapor at
a rate of 2.8 micrograms per cubic meter of air breathed in the resting
state, and their emission rate accelerates dramatically (as high as 49 mgs)
after minimal mechanical, chemical, and temperature stimulations. It is also
very volatile. This means that "metallic" mercury gives off mercury vapor
when agitated, compressed or exposed to increases in temperature. Mercury
vapor--which is colorless, tasteless and odorless--if inhaled into the
lungs, passes into your bloodstream for distribution to all body tissues. It
is at this point that biotransformation begins. Some of the mercury vapor
remains unchanged, and some of it is oxidized. (This means to remove a pair
of hydrogen atoms and to combine with oxygen. Chemically it means the
increase of a positive electrical charge and the decrease of the negative
charge, which in effect ionizes the vapor). The unchanged portion exists
dissolved in the blood lipids (fats). The toxic effects are produced by that
portion that is oxidized into mercuric ions which occurs partly in the
blood, partly in the tissues but mainly in the red blood cells.
Several researchers, beginn