From: Jan Drew on
http://discovermagazine.com/2005/mar/our-preferred-poison

Let’s start with a straightforward fact:

Mercury is unimaginably toxic and dangerous.

A single drop on a human hand can be irreversibly fatal.

A single drop in a large lake can make all

the fish in it unsafe to eat.

Often referred to as quicksilver, mercury is the only common metal
that is liquid at room temperature. Alchemists, including the young
Sir Isaac Newton, believed it was the source of gold. In the modern
era, it became a common ingredient of paints, diuretics, pesticides,
batteries, fluorescent lightbulbs, skin creams, antifungal agents,
vaccines for children, and of course, thermometers. There is probably
some in your mouth right now: So-called silver dental fillings are
half mercury.

Mercury is also a by-product of many industrial processes. In the
United States coal-fired power plants alone pump about 50 tons of it
into the air each year. That mercury rains out of the sky into oceans,
lakes, rivers, and streams, where it becomes concentrated in the flesh
of fish, shellfish, seals, and whales. Last year the Food and Drug
Administration determined there is so much mercury in the sea that
women of childbearing age should severely limit their consumption of
larger ocean fish. The warning comes too late for many mothers. A
nationwide survey by the Centers for Disease Control shows that one in
12 women of childbearing age already have unsafe blood levels of
mercury and that as many as 600,000 babies in the United States could
be at risk. But that begs a critical question: At risk for what?

Infants born to mothers contaminated by mercury in Japan’s Minamata
Bay in 1956 had profound neurological disabilities including deafness,
blindness, mental retardation, and cerebral palsy. In adults, mercury
poisoning can cause numbness, stumbling, dementia, and death. “It’s no
secret that mercury exposure is highly toxic,” says toxicologist Alan
Stern, a contributor to a 2000 National Research Council report on
mercury toxicity. But high-level exposures like those at Minamata
cannot help scientists determine whether six silver fillings and a
weekly tuna-salad sandwich will poison you or an unborn child. “The
question is, what are the effects at low levels of exposure?” he says.

Data now suggest effects might occur at levels lower than anyone
suspected. Some studies show that children who were exposed to tiny
amounts of mercury in utero have slower reflexes, language deficits,
and shortened attention spans. In adults, recent studies show a
possible link between heart disease and mercury ingested from eating
fish. Other groups claim mercury exposure is responsible for
Parkinson’s disease, multiple sclerosis, Alzheimer’s, and the
escalating rate of autism.

How—and in what form—mercury inflicts damage is still unclear. Yet
scientists and policymakers agree that more regulation is imperative.
The Environmental Protection Agency plans to finalize its
controversial first rule on reducing mercury emissions from power
plants this month, and delegates from the United Nations Environment
Programme met in late February to discuss an international convention
limiting mercury use and emissions.

A decade ago researchers and lawmakers agreed that lead, another heavy
metal, was harmful to children at levels one-sixth as high as
previously recognized. But it took scientists decades to establish the
scope and subtlety of lead poisoning. Mercury is now a ubiquitous
contaminant. The average American may have several micrograms of it in
each liter of blood, and the atmospheric burden of mercury has perhaps
tripled since the industrial age. Whatever needs to be done to protect
humanity from its love affair with quicksilver, it had better happen
soon.

In August 1996 Karen Wetterhahn, a chemistry professor at Dartmouth
College in Hanover, New Hampshire, spilled a few drops of a laboratory
compound called dimethyl mercury onto one of her hands. She was
wearing latex lab gloves, so she didn’t think much of it. A colleague
saw her at a conference the following November. “She said she thought
she was coming down with the flu,” says toxicologist Vas Aposhian of
the University of Arizona. By the time Wetterhahn was diagnosed with
mercury poisoning, in January, it was too late. Despite subsequent
treatment that helped clear the metal from her body, she lapsed into a
vegetative state in February and died the following June.

Scientists are at a loss to explain why mercury often takes months to
exert its effects. “If we knew that, we’d know a lot more about how
mercury poisons the brain,” says Tom Clarkson, a toxicologist at the
University of Rochester Medical Center.

The degree of mercury’s toxicity depends on the form and route of
exposure. You can swallow the liquid form of elemental mercury without
much fear because it doesn’t easily penetrate the lining of the
stomach and intestines. On the other hand, liquid mercury vaporizes at
room temperature, and when you inhale the vapor it moves right from
the lungs to the bloodstream to the brain. A broken thermometer can
release enough mercury vapor to poison the air in a room—one reason
why some cities and several states discourage the sale of mercury
fever thermometers.

Mercury also binds with other elements in salts and organic compounds
of varying toxicity. Dimethyl mercury, the substance that poisoned the
Dartmouth chemist, is a synthetic form of organic mercury rarely found
outside a lab. A simpler organic compound called methylmercury is of
greater concern because methyl- mercury is the form found in the flesh
of fish.

Seafood is one of the two most common sources of mercury exposure in
adults. Although concentrations of mercury in air and water are
increasing, they are still too small for alarm. But bacteria process
the mercury in lakes and oceans into a form that accumulates in living
tissue. Plankton take in the bacteria and are in turn eaten by small
fish. With each meal, the mercury concentration rises. Then larger
fish eat the small fish, increasing tissue concentrations still more.
Fish at the top of the food chain accumulate the most mercury. The
species singled out by the recent FDA advisory—big predators such as
albacore tuna, shark, and swordfish—can have 100 times more mercury in
their tissues than smaller fish do.

The methylmercury in fish passes readily from the human gut to the
bloodstream and on into all organs and tissues. It seems to act most
powerfully on the brain because the compound is strongly attracted to
fatty molecules called lipids, and the brain has the highest lipid
content of any organ. Methylmercury crosses the protective blood-brain
barrier by binding with an essential amino acid that has dedicated
carrier proteins for shunting it into brain cells. Once inside brain
cells, some of it gets converted to an inorganic form that sticks to
and disables many structural proteins and enzymes essential to cell
function. “It can destroy the biological function of any protein it
binds to,” says Boyd Haley, a biochemist at the University of
Kentucky.

Researchers learned how much mercury the body can tolerate from
studies of victims of catastrophic poisoning, such as the Japanese
sickened by eating fish from Minamata Bay and the Iraqis who ate grain
treated with a methylmercury-based preservative in the early 1970s.
But those studies do not reveal how little mercury it takes to cause
harm. At the time of her diagnosis, the Dartmouth chemist had 4,000
micrograms of mercury per liter in her blood. A diet consistently high
in fish can create a blood-mercury level of about 25 micrograms per
liter. That’s far below a lethal dose, but it still may not be safe.

Concerns about low-level toxicity haunt discussions of another
ubiquitous source of mercury exposure: silver dental fillings.
Elemental mercury, which makes up half of silver fillings, releases
mercury vapor, just as liquid mercury does. The vapor from dental
amalgams is the primary source of the one to eight micrograms of
mercury per liter of blood, that is, according to some sources, in the
average American adult. That amount uncomfortably overlaps the
Environmental Protection Agency’s current safe level of 5.8 micrograms
per liter. But the EPA’s safety level is based on methylmercury
exposure, about which more is known. No human studies have assessed
prolonged exposure to low levels of mercury vapor. One study hints at
subtle neural and behavioral anomalies in dentists, who collectively
use 300 metric tons of mercury in amalgams each year and who often
have two to five times the typical concentration of mercury in their
urine.

I think the methylmercury in fish is probably our least toxic
exposure,” says Haley, who broadcasts the hazards of dental fillings.

Silver-mercury fillings have never been tested for safety. “The
amalgam question will never be solved until we do a clinical trial
like those we do with other medical devices,” says Aposhian.

“It’s really unclear what’s going on with dental amalgams,” says
Stern, who notes that the issue is complicated by the potential for
panic and lawsuits. “It’s a snake pit.”

One of the lessons of Minamata is that mercury, like lead, is harder
on fetuses than on the women carrying them, or adults in general. In
the Japanese event, women with no overt symptoms of poisoning gave
birth to severely disabled children. “It was evident there was a major
difference in susceptibility between the developing brain and the
mature brain,” says Philippe Grandjean, an epidemiologist at the
Harvard University School of Public Health. “When we saw serious
poisonings in Minamata, that made us wonder whether mercury could be
like lead.”

Studies of lead have shown that IQ decreases approximately two or
three points for every doubling of prenatal and early postnatal
exposure. To see if mercury has comparable effects, Grandjean, along
with Pál Weihe at the University of Southern Denmark, is conducting
the largest study to date of children’s cognition and behavior in a
population routinely exposed to low levels of mercury. His work in the
Faeroe Islands of Denmark includes 1,000 mother-child pairs and spans
almost 20 years. In a typical year, Faeroe islanders consume 1,000
pilot whales, or one whale for every 50 islanders. “They belong to one
of the most fish-eating populations in the world,” says Grandjean.

Whale meat is one of the most highly contaminated seafoods because
whales are at the top of the food chain. Even so, the mercury content
of whale meat is considerably lower than that of the hypertoxic
Minamata fish. An earlier study of shark eaters in New Zealand
suggested that relatively high levels of mercury in a mother’s hair
during pregnancy correlated with a loss of three IQ points in her
child. High levels, in that study, were identified as six parts per
million and above in the hair shaft.

Grandjean gave a battery of sophisticated cognitive and developmental
tests to the Faeroese children when they were 7 and 14. His results
indicate that IQ drops 1.5 points for every doubling in prenatal
exposure to mercury. The 2000 National Research Council report
concluded that the risk documented by Grandjean “is likely to be
sufficient to result in an increase in the number of children who have
to struggle to keep up in school.”

I think the methylmercury in fish is probably our least toxic
exposure,” says Haley, who broadcasts the hazards of dental fillings.

Silver-mercury fillings have never been tested for safety. “The
amalgam question will never be solved until we do a clinical trial
like those we do with other medical devices,” says Aposhian.

“It’s really unclear what’s going on with dental amalgams,” says
Stern, who notes that the issue is complicated by the potential for
panic and lawsuits. “It’s a snake pit.”

One of the lessons of Minamata is that mercury, like lead, is harder
on fetuses than on the women carrying them, or adults in general. In
the Japanese event, women with no overt symptoms of poisoning gave
birth to severely disabled children. “It was evident there was a major
difference in susceptibility between the developing brain and the
mature brain,” says Philippe Grandjean, an epidemiologist at the
Harvard University School of Public Health. “When we saw serious
poisonings in Minamata, that made us wonder whether mercury could be
like lead.”

Studies of lead have shown that IQ decreases approximately two or
three points for every doubling of prenatal and early postnatal
exposure. To see if mercury has comparable effects, Grandjean, along
with Pál Weihe at the University of Southern Denmark, is conducting
the largest study to date of children’s cognition and behavior in a
population routinely exposed to low levels of mercury. His work in the
Faeroe Islands of Denmark includes 1,000 mother-child pairs and spans
almost 20 years. In a typical year, Faeroe islanders consume 1,000
pilot whales, or one whale for every 50 islanders. “They belong to one
of the most fish-eating populations in the world,” says Grandjean.

Whale meat is one of the most highly contaminated seafoods because
whales are at the top of the food chain. Even so, the mercury content
of whale meat is considerably lower than that of the hypertoxic
Minamata fish. An earlier study of shark eaters in New Zealand
suggested that relatively high levels of mercury in a mother’s hair
during pregnancy correlated with a loss of three IQ points in her
child. High levels, in that study, were identified as six parts per
million and above in the hair shaft.

Grandjean gave a battery of sophisticated cognitive and developmental
tests to the Faeroese children when they were 7 and 14. His results
indicate that IQ drops 1.5 points for every doubling in prenatal
exposure to mercury. The 2000 National Research Council report
concluded that the risk documented by Grandjean “is likely to be
sufficient to result in an increase in the number of children who have
to struggle to keep up in school.”

“We learned there is a response at low levels,” says Grandjean. “It’s
not a huge loss, but it’s certainly not negligible.”

Yet in another large, long-term epidemiological study conducted on the
Seychelles Islands in the Indian Ocean, Clarkson has so far found no
effect on neurological development from prenatal exposure to low
levels of mercury in seafood. “We can’t exclude effects from 20 parts
per million or even 12 parts per million,” he notes. But he concludes
there is no graded risk that extends to the lowest exposure levels.

The 2000 research council report evaluated the Faeroe, Seychelles, and
New Zealand studies and recommended that the EPA set safety standards
based on Grandjean’s more sobering findings. The agency did. Then, for
good measure, it added a 10-fold uncertainty factor—a safety margin to
protect against scientific unknowns and individual differences in
response to a toxin. The uncertainty factor lowers the threshold to a
figure of 5.8 micrograms per liter of blood and 1.2 parts per million
in hair.

The problem with safety factors is that they create a toxicological
limbo between demonstrably harmful doses and levels that have been
declared safe. Thus, when Centers for Disease Control surveys find
that one in 12 American women of childbearing age—8 percent—have blood
mercury levels above the safety threshold, the implications aren’t
clear, either for them or for the children they bear. Epidemiologist
Tom Sinks says, “It doesn’t tell us there’s a hazard.”

“The whole idea of a safety factor is to protect people,” Clarkson
says. “You can’t turn it around to use as an indication of who’s at
risk. If you’re just above it, you aren’t necessarily in trouble.”

That kind of hedging, along with disagreement among population
studies, leaves regulators with plenty of wiggle room. The FDA, for
example, uses a more relaxed safety standard for mercury based on
studies from the 1970s and 1980s. Where the EPA safety level for daily
exposure is 0.1 microgram per kilogram (about 2.2 pounds) of body
weight, the FDA’s standard is about 0.4 microgram per kilogram per
day. The difference is four times as much mercury.

Concern about early exposure to mercury doesn’t end at birth. Until
recently, many infants received regular injections of mercury on a
state-mandated, medically sanctioned schedule. The mercury came from a
compound called thimerosal that has been used as a preservative in
vaccines and other medicines since the 1930s. In 1999 the FDA
recommended that thimerosal no longer be used in pediatric vaccines,
and manufacturers have removed it from all but the influenza vaccine.
But some scientists and many more aggrieved parents are convinced that
thimerosal in childhood vaccines has already caused, or at least
catalyzed, the U.S. epidemic of autism.

An estimated 400,000 Americans today have autism, a once rare
neurological disorder characterized by social withdrawal, difficulty
communicating, and involuntary, repetitive movements. Although the
exact numbers are in dispute, the rate of diagnosis seems to have
climbed sharply in the last decade. In California the incidence of
autism was six times higher in 2002 than in 1987.

During that period, federal health officials added four new kinds of
vaccines to the childhood immunization schedule, and the amount of
mercury routinely administered to infants in the first six months of
life more than doubled. Throughout the 1990s, a 3-month-old baby might
receive as much as 63 micrograms of mercury in a single visit to a
doctor—roughly 100 times the daily EPA safety level. By the age of 6
months, properly immunized children were exposed to at least 188
micrograms of mercury in a series of at least nine injections.
Although the 1999 FDA action minimized such exposure, some infant flu
vaccines still contain 12.5 micrograms of mercury per dose—more than
10 times the daily EPA safety level for a 20-pound baby.

Circumstantial evidence also implicates mercury in autism. Some of the
symptoms of autism and mercury poisoning are similar, and Haley has
garnered evidence from hair samples that autistic children do not
clear mercury from their bodies as efficiently as most kids do. They
may have a genetic susceptibility that allows more mercury to
accumulate in their tissues, he says. That could make them more
vulnerable to mercury-laced vaccines and the continuous low-level
exposure from their mothers’ dental fillings. “It is amazing to me
that no one has taken the tissue of autistic children to see if there
is excess mercury there,” Aposhian told a committee at the Institute
of Medicine in Washington, D.C., last year. “That’s one thing that
really has to be done.”

There are other sources of uncertainty. The form of mercury in
thimerosal—an organic compound called ethyl mercury—is the least
studied of all mercury’s incarnations. When scientists argue about its
toxicity, they typically rely on data from methylmercury, which may
not be an equivalent form of exposure. Experts even disagree about
whether ethyl mercury can cross the blood-brain barrier. (It probably
does.) “There are no good ways to measure ethyl mercury in tissue,”
toxicologist Polly Sager of the National Institute of Allergy and
Infectious Diseases told the Institute of Medicine committee.

The Institute of Medicine concluded last May that no claim could be
made for a causal link between mercury-laced vaccines and autism, but
several independent researchers had complained that their access to
federal vaccine databases, which could provide evidence of a link, had
been repeatedly blocked. A few scientists, including Haley and
neuropharmacologist Richard Deth of Northeastern University in Boston,
continue to study possible mechanisms for the connection. Deth
reported last year, for example, that in human nerve cells thimerosal
blocks a chemical reaction called methylation that is critical to gene
activity and that is also disabled by exposure to lead.

The report that first triggered worries about a connection between
vaccines and autism was published in the British medical journal The
Lancet in 1998. It described eight children whose behavioral problems
surfaced within two weeks of receiving the measles-mumps-rubella
vaccine. The Lancet and most of the article’s coauthors ultimately
disowned the study because its lead author had not divulged that he
was also being paid to conduct research for parents seeking to sue
vaccine manufacturers. Nonetheless, the number of parents in the
United Kingdom willing to immunize their babies with the vaccine
dropped from 90 percent in 1998 to less than 80 percent in 2004.
From: Peter B. on

"Jan Drew" <jdrew63929(a)aol.com> wrote in message
news:dafe6472-7bfb-4898-a7fd-c235c932b388(a)q8g2000vbm.googlegroups.com...

Deleted unfounded copyright text.

Janet Drew lies..................................a lot!


From: Jan Drew on

More options May 22, 8:59 pm

Newsgroups: misc.health.alternative, sci.med.dentistry,
misc.kids.health, talk.politics.medicine
From: Jan Drew <jdrew63...(a)aol.com>
Date: Sat, 22 May 2010 17:59:21 -0700 (PDT)
Local: Sat, May 22 2010 8:59 pm
Subject: Our Preferred Poison
Reply | Reply to author | Forward | Print | View thread | Show
original | Remove | Report this message | Find messages by this
author
http://discovermagazine.com/2005/mar/our-preferred-poison

Let’s start with a straightforward fact:


Mercury is unimaginably toxic and dangerous.


A single drop on a human hand can be irreversibly fatal.


A single drop in a large lake can make all


the fish in it unsafe to eat.


Often referred to as quicksilver, mercury is the only common metal
that is liquid at room temperature. Alchemists, including the young
Sir Isaac Newton, believed it was the source of gold. In the modern
era, it became a common ingredient of paints, diuretics, pesticides,
batteries, fluorescent lightbulbs, skin creams, antifungal agents,
vaccines for children, and of course, thermometers. There is probably
some in your mouth right now: So-called silver dental fillings are
half mercury.


Mercury is also a by-product of many industrial processes. In the
United States coal-fired power plants alone pump about 50 tons of it
into the air each year. That mercury rains out of the sky into
oceans,
lakes, rivers, and streams, where it becomes concentrated in the
flesh
of fish, shellfish, seals, and whales. Last year the Food and Drug
Administration determined there is so much mercury in the sea that
women of childbearing age should severely limit their consumption of
larger ocean fish. The warning comes too late for many mothers. A
nationwide survey by the Centers for Disease Control shows that one
in
12 women of childbearing age already have unsafe blood levels of
mercury and that as many as 600,000 babies in the United States could
be at risk. But that begs a critical question: At risk for what?


Infants born to mothers contaminated by mercury in Japan’s Minamata
Bay in 1956 had profound neurological disabilities including
deafness,
blindness, mental retardation, and cerebral palsy. In adults, mercury
poisoning can cause numbness, stumbling, dementia, and death. “It’s
no
secret that mercury exposure is highly toxic,” says toxicologist Alan
Stern, a contributor to a 2000 National Research Council report on
mercury toxicity. But high-level exposures like those at Minamata
cannot help scientists determine whether six silver fillings and a
weekly tuna-salad sandwich will poison you or an unborn child. “The
question is, what are the effects at low levels of exposure?” he
says.


Data now suggest effects might occur at levels lower than anyone
suspected. Some studies show that children who were exposed to tiny
amounts of mercury in utero have slower reflexes, language deficits,
and shortened attention spans. In adults, recent studies show a
possible link between heart disease and mercury ingested from eating
fish. Other groups claim mercury exposure is responsible for
Parkinson’s disease, multiple sclerosis, Alzheimer’s, and the
escalating rate of autism.


How—and in what form—mercury inflicts damage is still unclear. Yet
scientists and policymakers agree that more regulation is imperative.
The Environmental Protection Agency plans to finalize its
controversial first rule on reducing mercury emissions from power
plants this month, and delegates from the United Nations Environment
Programme met in late February to discuss an international convention
limiting mercury use and emissions.


A decade ago researchers and lawmakers agreed that lead, another
heavy
metal, was harmful to children at levels one-sixth as high as
previously recognized. But it took scientists decades to establish
the
scope and subtlety of lead poisoning. Mercury is now a ubiquitous
contaminant. The average American may have several micrograms of it
in
each liter of blood, and the atmospheric burden of mercury has
perhaps
tripled since the industrial age. Whatever needs to be done to
protect
humanity from its love affair with quicksilver, it had better happen
soon.


In August 1996 Karen Wetterhahn, a chemistry professor at Dartmouth
College in Hanover, New Hampshire, spilled a few drops of a
laboratory
compound called dimethyl mercury onto one of her hands. She was
wearing latex lab gloves, so she didn’t think much of it. A colleague
saw her at a conference the following November. “She said she thought
she was coming down with the flu,” says toxicologist Vas Aposhian of
the University of Arizona. By the time Wetterhahn was diagnosed with
mercury poisoning, in January, it was too late. Despite subsequent
treatment that helped clear the metal from her body, she lapsed into
a
vegetative state in February and died the following June.


Scientists are at a loss to explain why mercury often takes months to
exert its effects. “If we knew that, we’d know a lot more about how
mercury poisons the brain,” says Tom Clarkson, a toxicologist at the
University of Rochester Medical Center.


The degree of mercury’s toxicity depends on the form and route of
exposure. You can swallow the liquid form of elemental mercury
without
much fear because it doesn’t easily penetrate the lining of the
stomach and intestines. On the other hand, liquid mercury vaporizes
at
room temperature, and when you inhale the vapor it moves right from
the lungs to the bloodstream to the brain. A broken thermometer can
release enough mercury vapor to poison the air in a room—one reason
why some cities and several states discourage the sale of mercury
fever thermometers.


Mercury also binds with other elements in salts and organic compounds
of varying toxicity. Dimethyl mercury, the substance that poisoned
the
Dartmouth chemist, is a synthetic form of organic mercury rarely
found
outside a lab. A simpler organic compound called methylmercury is of
greater concern because methyl- mercury is the form found in the
flesh
of fish.


Seafood is one of the two most common sources of mercury exposure in
adults. Although concentrations of mercury in air and water are
increasing, they are still too small for alarm. But bacteria process
the mercury in lakes and oceans into a form that accumulates in
living
tissue. Plankton take in the bacteria and are in turn eaten by small
fish. With each meal, the mercury concentration rises. Then larger
fish eat the small fish, increasing tissue concentrations still more.
Fish at the top of the food chain accumulate the most mercury. The
species singled out by the recent FDA advisory—big predators such as
albacore tuna, shark, and swordfish—can have 100 times more mercury
in
their tissues than smaller fish do.


The methylmercury in fish passes readily from the human gut to the
bloodstream and on into all organs and tissues. It seems to act most
powerfully on the brain because the compound is strongly attracted to
fatty molecules called lipids, and the brain has the highest lipid
content of any organ. Methylmercury crosses the protective blood-
brain
barrier by binding with an essential amino acid that has dedicated
carrier proteins for shunting it into brain cells. Once inside brain
cells, some of it gets converted to an inorganic form that sticks to
and disables many structural proteins and enzymes essential to cell
function. “It can destroy the biological function of any protein it
binds to,” says Boyd Haley, a biochemist at the University of
Kentucky.


Researchers learned how much mercury the body can tolerate from
studies of victims of catastrophic poisoning, such as the Japanese
sickened by eating fish from Minamata Bay and the Iraqis who ate
grain
treated with a methylmercury-based preservative in the early 1970s.
But those studies do not reveal how little mercury it takes to cause
harm. At the time of her diagnosis, the Dartmouth chemist had 4,000
micrograms of mercury per liter in her blood. A diet consistently
high
in fish can create a blood-mercury level of about 25 micrograms per
liter. That’s far below a lethal dose, but it still may not be safe.


Concerns about low-level toxicity haunt discussions of another
ubiquitous source of mercury exposure: silver dental fillings.
Elemental mercury, which makes up half of silver fillings, releases
mercury vapor, just as liquid mercury does. The vapor from dental
amalgams is the primary source of the one to eight micrograms of
mercury per liter of blood, that is, according to some sources, in
the
average American adult. That amount uncomfortably overlaps the
Environmental Protection Agency’s current safe level of 5.8
micrograms
per liter. But the EPA’s safety level is based on methylmercury
exposure, about which more is known. No human studies have assessed
prolonged exposure to low levels of mercury vapor. One study hints at
subtle neural and behavioral anomalies in dentists, who collectively
use 300 metric tons of mercury in amalgams each year and who often
have two to five times the typical concentration of mercury in their
urine.


I think the methylmercury in fish is probably our least toxic
exposure,” says Haley, who broadcasts the hazards of dental fillings.


Silver-mercury fillings have never been tested for safety. “The
amalgam question will never be solved until we do a clinical trial
like those we do with other medical devices,” says Aposhian.


“It’s really unclear what’s going on with dental amalgams,” says
Stern, who notes that the issue is complicated by the potential for
panic and lawsuits. “It’s a snake pit.”


One of the lessons of Minamata is that mercury, like lead, is harder
on fetuses than on the women carrying them, or adults in general. In
the Japanese event, women with no overt symptoms of poisoning gave
birth to severely disabled children. “It was evident there was a
major
difference in susceptibility between the developing brain and the
mature brain,” says Philippe Grandjean, an epidemiologist at the
Harvard University School of Public Health. “When we saw serious
poisonings in Minamata, that made us wonder whether mercury could be
like lead.”


Studies of lead have shown that IQ decreases approximately two or
three points for every doubling of prenatal and early postnatal
exposure. To see if mercury has comparable effects, Grandjean, along
with Pál Weihe at the University of Southern Denmark, is conducting
the largest study to date of children’s cognition and behavior in a
population routinely exposed to low levels of mercury. His work in
the
Faeroe Islands of Denmark includes 1,000 mother-child pairs and spans
almost 20 years. In a typical year, Faeroe islanders consume 1,000
pilot whales, or one whale for every 50 islanders. “They belong to
one
of the most fish-eating populations in the world,” says Grandjean.


Whale meat is one of the most highly contaminated seafoods because
whales are at the top of the food chain. Even so, the mercury content
of whale meat is considerably lower than that of the hypertoxic
Minamata fish. An earlier study of shark eaters in New Zealand
suggested that relatively high levels of mercury in a mother’s hair
during pregnancy correlated with a loss of three IQ points in her
child. High levels, in that study, were identified as six parts per
million and above in the hair shaft.


Grandjean gave a battery of sophisticated cognitive and developmental
tests to the Faeroese children when they were 7 and 14. His results
indicate that IQ drops 1.5 points for every doubling in prenatal
exposure to mercury. The 2000 National Research Council report
concluded that the risk documented by Grandjean “is likely to be
sufficient to result in an increase in the number of children who
have
to struggle to keep up in school.”


I think the methylmercury in fish is probably our least toxic
exposure,” says Haley, who broadcasts the hazards of dental fillings.


Silver-mercury fillings have never been tested for safety. “The
amalgam question will never be solved until we do a clinical trial
like those we do with other medical devices,” says Aposhian.


“It’s really unclear what’s going on with dental amalgams,” says
Stern, who notes that the issue is complicated by the potential for
panic and lawsuits. “It’s a snake pit.”


One of the lessons of Minamata is that mercury, like lead, is harder
on fetuses than on the women carrying them, or adults in general. In
the Japanese event, women with no overt symptoms of poisoning gave
birth to severely disabled children. “It was evident there was a
major
difference in susceptibility between the developing brain and the
mature brain,” says Philippe Grandjean, an epidemiologist at the
Harvard University School of Public Health. “When we saw serious
poisonings in Minamata, that made us wonder whether mercury could be
like lead.”


Studies of lead have shown that IQ decreases approximately two or
three points for every doubling of prenatal and early postnatal
exposure. To see if mercury has comparable effects, Grandjean, along
with Pál Weihe at the University of Southern Denmark, is conducting
the largest study to date of children’s cognition and behavior in a
population routinely exposed to low levels of mercury. His work in
the
Faeroe Islands of Denmark includes 1,000 mother-child pairs and spans
almost 20 years. In a typical year, Faeroe islanders consume 1,000
pilot whales, or one whale for every 50 islanders. “They belong to
one
of the most fish-eating populations in the world,” says Grandjean.


Whale meat is one of the most highly contaminated seafoods because
whales are at the top of the food chain. Even so, the mercury content
of whale meat is considerably lower than that of the hypertoxic
Minamata fish. An earlier study of shark eaters in New Zealand
suggested that relatively high levels of mercury in a mother’s hair
during pregnancy correlated with a loss of three IQ points in her
child. High levels, in that study, were identified as six parts per
million and above in the hair shaft.


Grandjean gave a battery of sophisticated cognitive and developmental
tests to the Faeroese children when they were 7 and 14. His results
indicate that IQ drops 1.5 points for every doubling in prenatal
exposure to mercury. The 2000 National Research Council report
concluded that the risk documented by Grandjean “is likely to be
sufficient to result in an increase in the number of children who
have
to struggle to keep up in school.”


“We learned there is a response at low levels,” says Grandjean. “It’s
not a huge loss, but it’s certainly not negligible.”


Yet in another large, long-term epidemiological study conducted on
the
Seychelles Islands in the Indian Ocean, Clarkson has so far found no
effect on neurological development from prenatal exposure to low
levels of mercury in seafood. “We can’t exclude effects from 20 parts
per million or even 12 parts per million,” he notes. But he concludes
there is no graded risk that extends to the lowest exposure levels.


The 2000 research council report evaluated the Faeroe, Seychelles,
and
New Zealand studies and recommended that the EPA set safety standards
based on Grandjean’s more sobering findings. The agency did. Then,
for
good measure, it added a 10-fold uncertainty factor—a safety margin
to
protect against scientific unknowns and individual differences in
response to a toxin. The uncertainty factor lowers the threshold to a
figure of 5.8 micrograms per liter of blood and 1.2 parts per million
in hair.


The problem with safety factors is that they create a toxicological
limbo between demonstrably harmful doses and levels that have been
declared safe. Thus, when Centers for Disease Control surveys find
that one in 12 American women of childbearing age—8 percent—have
blood
mercury levels above the safety threshold, the implications aren’t
clear, either for them or for the children they bear. Epidemiologist
Tom Sinks says, “It doesn’t tell us there’s a hazard.”


“The whole idea of a safety factor is to protect people,” Clarkson
says. “You can’t turn it around to use as an indication of who’s at
risk. If you’re just above it, you aren’t necessarily in trouble.”


That kind of hedging, along with disagreement among population
studies, leaves regulators with plenty of wiggle room. The FDA, for
example, uses a more relaxed safety standard for mercury based on
studies from the 1970s and 1980s. Where the EPA safety level for
daily
exposure is 0.1 microgram per kilogram (about 2.2 pounds) of body
weight, the FDA’s standard is about 0.4 microgram per kilogram per
day. The difference is four times as much mercury.


Concern about early exposure to mercury doesn’t end at birth. Until
recently, many infants received regular injections of mercury on a
state-mandated, medically sanctioned schedule. The mercury came from
a
compound called thimerosal that has been used as a preservative in
vaccines and other medicines since the 1930s. In 1999 the FDA
recommended that thimerosal no longer be used in pediatric vaccines,
and manufacturers have removed it from all but the influenza vaccine.
But some scientists and many more aggrieved parents are convinced
that
thimerosal in childhood vaccines has already caused, or at least
catalyzed, the U.S. epidemic of autism.


An estimated 400,000 Americans today have autism, a once rare
neurological disorder characterized by social withdrawal, difficulty
communicating, and involuntary, repetitive movements. Although the
exact numbers are in dispute, the rate of diagnosis seems to have
climbed sharply in the last decade. In California the incidence of
autism was six times higher in 2002 than in 1987.


During that period, federal health officials added four new kinds of
vaccines to the childhood immunization schedule, and the amount of
mercury routinely administered to infants in the first six months of
life more than doubled. Throughout the 1990s, a 3-month-old baby
might
receive as much as 63 micrograms of mercury in a single visit to a
doctor—roughly 100 times the daily EPA safety level. By the age of 6
months, properly immunized children were exposed to at least 188
micrograms of mercury in a series of at least nine injections.
Although the 1999 FDA action minimized such exposure, some infant flu
vaccines still contain 12.5 micrograms of mercury per dose—more than
10 times the daily EPA safety level for a 20-pound baby.


Circumstantial evidence also implicates mercury in autism. Some of
the
symptoms of autism and mercury poisoning are similar, and Haley has
garnered evidence from hair samples that autistic children do not
clear mercury from their bodies as efficiently as most kids do. They
may have a genetic susceptibility that allows more mercury to
accumulate in their tissues, he says. That could make them more
vulnerable to mercury-laced vaccines and the continuous low-level
exposure from their mothers’ dental fillings. “It is amazing to me
that no one has taken the tissue of autistic children to see if there
is excess mercury there,” Aposhian told a committee at the Institute
of Medicine in Washington, D.C., last year. “That’s one thing that
really has to be done.”


There are other sources of uncertainty. The form of mercury in
thimerosal—an organic compound called ethyl mercury—is the least
studied of all mercury’s incarnations. When scientists argue about
its
toxicity, they typically rely on data from methylmercury, which may
not be an equivalent form of exposure. Experts even disagree about
whether ethyl mercury can cross the blood-brain barrier. (It probably
does.) “There are no good ways to measure ethyl mercury in tissue,”
toxicologist Polly Sager of the National Institute of Allergy and
Infectious Diseases told the Institute of Medicine committee.


The Institute of Medicine concluded last May that no claim could be
made for a causal link between mercury-laced vaccines and autism, but
several independent researchers had complained that their access to
federal vaccine databases, which could provide evidence of a link,
had
been repeatedly blocked. A few scientists, including Haley and
neuropharmacologist Richard Deth of Northeastern University in
Boston,
continue to study possible mechanisms for the connection. Deth
reported last year, for example, that in human nerve cells thimerosal
blocks a chemical reaction called methylation that is critical to
gene
activity and that is also disabled by exposure to lead.


The report that first triggered worries about a connection between
vaccines and autism was published in the British medical journal The
Lancet in 1998. It described eight children whose behavioral problems
surfaced within two weeks of receiving the measles-mumps-rubella
vaccine. The Lancet and most of the article’s coauthors ultimately
disowned the study because its lead author had not divulged that he
was also being paid to conduct research for parents seeking to sue
vaccine manufacturers. Nonetheless, the number of parents in the
United Kingdom willing to immunize their babies with the vaccine
dropped from 90 percent in 1998 to less than 80 percent in 2004.



From: Mark Probert-Drew on
On May 22, 8:59 pm, Jan Drew <jdrew63...(a)aol.com> wrote:
> http://discovermagazine.com/2005/mar/our-preferred-poison
>
> Let’s start with a straightforward fact:
>
> Mercury is unimaginably toxic and dangerous.

I can imagine it.

> A single drop on a human hand can be irreversibly fatal.

Hogwash. As a kid, I used to get some from my dentist and play with
it.

I have lived to an age which Jan Drool cannot even calculate. Call me
Methusallah.



From: Steven Bornfeld on
Mark Probert-Drew wrote:
>
> Hogwash. As a kid, I used to get some from my dentist and play with
> it.


I did too. I wouldn't recommend it as an activity to my daughter though.


>
> I have lived to an age which Jan Drool cannot even calculate. Call me
> Methusallah.


I genuflect in your general direction.

Steve
>
>
>