For centuries, lead contamination has undermined intelligence and debased
behavior. Only now are we beginning to fully understand how this heavy
metal
damages the brain, especially the prefrontal cortex, that fragile headquarters
of our
humanity.
A Leaden History
"Dear Friend,
I recollect that, when I had the great Pleasure of seeing you at
Southampton, now a 12 months since, we had some Conversation on
the bad Effects of Lead taken inwardly; and that at your Request I
promis'd to send you in writing a particular account of several Facts I
there mentioned to you, of which you thought some good use might
be made. I now sit down to fulfill that Promise."
So begins a letter written by Benjamin Franklin to Benjamin Vaughan on
July 31,
1786. His recollection of lead's dangers begins in his boyhood Boston,
where rum
distilleries were prohibited from using leaden still-heads because they
contaminated
the rum with lead — causing people to lose the use of their limbs.
Later, as an 18-year old printer's compositor in London, advice of an old
workman
may have preserved Franklin's future ability to write. He discouraged young
Benjamin from warming the cases of leaden types before the fire. Although
it made
the cold metal easier to handle, others who followed the practice had met
with
disaster:
"One of whom that used to earn his Guinea a Week, could not then
make more than ten shillings, and the other, who had the Dangles, but
seven and sixpence. This, with a kind of obscure Pain, that I had
sometimes felt, as it were in the Bones of my Hand when working
over the Types made very hot, induced me to omit the Practice."
Flash Forward
In 1998 the Centers for Disease Control and Prevention (CDCP) reported
that
nearly a million American children between the ages of one and five have
the toxic
metal lead in their blood at concentrations above 10 micrograms per deciliter
(ug/dL), the current threshold of safety established in 1991. [1] This
was chosen as
the "unsafe" level mainly because it was the lowest level that could be
detected with
an inexpensive test. According to the CDCP, setting the standard lower
would
burden the country's healthcare system. [2]
Actually, there is no safe dose of lead in children's blood. After summarizing
the
research, in 1993 the National Research Council concluded "there is growing
evidence that there is no effective threshold for some of the adverse effects
of lead.
. . . Even very small exposures to lead can produce subtle effects in humans."
[3]
Lead Affects Children the Most
Lead in the body can cause permanent damage to the central nervous system,
the
brain, and kidneys. This commonly results in behavior and learning problems,
hearing problems, headaches, high blood pressure, slowed growth, reproductive
problems, digestive problems, muscle and joint pain. The effects of lead
poisoning
are cumulative and can last a lifetime. They are usually irreversible —
especially in
sensitive populations such as fetuses, children, and pregnant women.
Lead is most devastating to unborn children, because the "placental barrier"
does
not protect the developing fetus from lead in maternal blood. This placental
transfer
of lead begins as early as the 12th week of gestation and continues throughout
fetal
development. [4]
The risk of spontaneous abortion nearly doubles for every 5 ug/dL increase
in
blood lead levels, according to the results of a two-year Mexican study
reported in
the Sept. 15, 1999 issue of the American Journal of Epidemiology.
Lead Lowers Intelligence
In 1995, the American Academy of Pediatrics reviewed 18 scientific studies
on the
correlation between children's mental abilities and lead in their blood.
"The
relationship between lead levels and IQ deficits was found to be remarkably
consistent," the Academy said. "A number of studies have found that for
every 10
ug/dL increase in blood lead levels, there was a lowering of mean IQ in
children by
4 to 7 points." [5]
This drop has staggering implications. As Theo Coburn describes in her
landmark
1994 book, Our Stolen Future:
"With the current average IQ score of 100, a population of 100
million will have 2.3 million intellectually gifted people who score
above 130. Though it might not sound like much, if the average were
to drop just five points to 95 . . . only 990,000 would score above
130, so this society would have lost more than half its high-powered
minds with the capacity to become the most gifted doctors, scientists,
college professors, inventors, or writers.
"At the same time, this downward shift would result in a greater
number of slow learners, with IQ scores around 70, who would
require special remedial education, an already costly educational
burden, and who may not be able to fill many of the more highly
skilled jobs in a technological society. Given the daunting array of
problems we face as nations and as a world community, the last thing
we can afford is the loss of human intelligence and problem-solving
powers."
Attention-Deficits
A 1996 study at the University of Massachusetts evaluated the relationship
between lead levels in the hair of children and their attention-deficit
behaviors in the
classroom. It found a "striking dose-response relationship between levels
of lead
and negative teacher ratings. . . An even stronger relationship existed
between
physician-diagnosed attention-deficit hyperactivity disorder and hair lead
in the
same children." [6] A similar study done at Vrije Universiteit of Amsterdam
found
that children with relatively high concentrations of lead in their hair
"were
significantly less flexible in changing their focus of attention." [7]
Experiments at the University of Rochester School of Medicine found that
animals
exposed to lead exhibited behaviors similar those observed in children
diagnosed
with attention deficit hyperactivity disorder — "impulsivity" and "inability
to inhibit
inappropriate responding." [8]
(Other environmental factors for ADHD are discussed in "The Attention-Deficit
Dilemma," in this website.)
International Crisis
The results of a two-year study conducted in India found that more than
50% of
children under 12 had blood lead levels higher than 10 micrograms per deciliter!
"Project Lead-Free" was conducted in six major Indian cities and involved
nearly
22,000 children, including toddlers, slum children, working children, school
children
in low and high economic groups, and pregnant women.
These findings were presented in February 1999 at an international conference
on
lead poisoning held in Bangalore, where the World Health Organization estimated
that 15 to 18 million children in developing countries are suffering from
permanent
brain damage due to lead poisoning. The greatest source of poisoning is
leaded
gasoline. Paints, cooking utensils, and drinking water systems are other
primary
sources.
These countries are only now beginning to address the problem, which is
extremely
serious according to Dr. Herbert L. Needleman, professor of psychiatry
and
pediatrics at the University of Pittsburgh. "Blood lead levels are terribly
high in
India, Bangladesh. . . . China has a serious problem and so does Russia,"
he said.
[9]
How Lead Violates the Brain
In their 1998 investigation into lead's effects on the brains of children,
Israeli
researchers found that, for starters, lead disrupts the main structural
components of
the blood-brain barrier, (by injuring the glial brain cells that surround
and protect
neurons and by damaging the capillaries that keep toxins out of the brain).
Once in the brain, lead-induced damage occurs primarily in the prefrontal
cerebral
cortex, cerebellum, and hippocampus. There it adversely affects many biological
activities at the molecular, cellular, and intracellular levels.
Writing in the July 1998 issue of Brain Research, neurologists at Shaare
Zedek
Medical Center in Jerusalem reported that lead interferes with the action
of calcium
and with the neurotransmitter systems that are crucial to regulating emotional
response, memory, and learning.
They found a direct link between low-level long-term exposure to lead and
deficits
in cognitive performance and behavior in childhood through adolescence.
They also
concluded that "there is no threshold below which lead remains without
effect on
the central nervous system."
Since learning requires the remodeling of the brain's synapses — the spaces
between neurons where information is exchanged — lead may specifically
affect
synaptic transmission. In 1999, neurologists at Johns Hopkins University
School of
Public Health proposed that the learning deficits caused by lead are due
to its
disruption of processes regulated by calcium (protein kinase C) at the
synapse.
[10]
Lead and Dementia
Animal studies done in the 1980s showed that lead inhibits myelination
and
microtubule assembly in the brain, as well as caused the formation of fibers
and
"aggregates of amorphous material." [11] This suggests that lead may be
involved in
senile dementia, although little research has been done in this area.
The November 1998 issue of the journal Epidemiology published a report
titled,
"Is chronic low-level lead exposure in early life an etiologic factor in
Alzheimer's
disease?" According to Dr. Prince at the London School of Hygiene and Tropical
Medicine and the Institute of Psychiatry, England:
"Few environmental risk factors for Alzheimer's disease have been
identified. This lack of information may reflect the fact that salient
factors affect most of the population in developed countries.
Furthermore, the critical period of exposure may be earlier than
hitherto suspected, during the first years of life, as the brain
differentiates and develops. Exposure to lead at levels lower than
those associated with evident toxicity causes mild intellectual
impairment in childhood. I hypothesize that this may be one of the
childhood exposures that also confers an additional risk for the onset
of Alzheimer's disease."
The Prefrontal Cortex and Your Moral Imperative
Your prefrontal cortex is the most human part of your brain. One of the
things it
allows you do is to see things from a different point of view, to walk
in someone
else's shoes — in a word, empathy. Since the 1980s, scientists have correlated
damage to the prefrontal cortex with psychopathic behavior and the inability
to
make morally and socially acceptable decisions.
Swedish researchers have found that the prefrontal cortex is precisely
the area of
the brain that is is impaired in murderers, rapists, and other violent
criminals who
repeatedly re-offend. At the November 1999 annual meeting of the Society
for
Neuroscience, Asa Bergvall and her colleagues from the University in Sweden
presented findings on their study of violent offenders.
The results were quite startling."The violent offenders are like the controls
in every
task but one, which taps prefrontal function," says Bergvall. "In that,
it was as if
they were retarded." They had an impaired ability to shift their attention
in order to
view the world in a different way — a function linked to the lateral prefrontal
cortex. Other, higher order executive functions of their prefrontal cortex
appeared
to be unimpaired.
Childhood Damage to the Prefrontal Cortex is the Worst
In a related presentation at the Society for Neuroscience meeting, researchers
reported that children who experience early prefrontal damage never completely
develop social or moral reasoning. Even on an intellectual level they cannot
refer to
such behavior because they have little concept of it.
In contrast, individuals with adult-acquired damage are usually aware of
what
proper social and moral behavior should be. However, they are unable to
act upon
it. Even though they have an intellectual memory of learned moral conduct,
they
cannot apply such behaviors.
A study at University of Iowa College of Medicine, published in the November
1999 Nature Neuroscience, reports on two cases of early brain damage to
the
prefrontal cortex, in which the patients as adults showed the same two
distinctive
features: an almost total lack of guilt and an inability to plan for the
future — but
were normal in almost every other type of mental ability.
The patients had problems with violence and "resemble psychopathic individuals,
who are characterized by high levels of aggression and antisocial behavior
performed without guilt or empathy for their victims," wrote Raymond Dolan
of
Institute of Neurology in London in an editorial that accompanied the research.
Their brains were just not capable of acquiring social and moral knowledge
even at
a normal level.
Unlike other areas of the brain, the prefrontal cortex is not particularly
plastic. If the
area responsible for moral and social awareness is damaged in childhood,
it can
never develop. Dolan suggested that this understanding of the brain will
require a
reappraisal of the way society deals with criminal behavior, because "problems
with
moral and social behavior may be rooted in physical problems in the brain."
As New York physician Dr. Charles Gant describes it: In evolutionary terms
the
prefrontal cortex is "the last part of the human brain to develop and is
one of the
first parts to lose its function when there is a generalized stress or
injury to the
central nervous system. Because this recent brain structure has not had
the benefit
of millions of extra years of 'road testing,' that the older, more rugged
parts of the
brain have had, it is more vulnerable to modern-era stress, neurotoxins,
and
nutritional deficiencies." [12]
Our Old Enemy, Lead, has a New Ally
Important ongoing research has revealed a widespread, serious risk co-factor
for
lead poisoning. And it is reminiscent of an incident described by Benjamin
Franklin
in his letter:
"But I have been told of a case in Europe, I forget the Place, where a
whole Family was afflicted with what we call Dry Bellyache, or Colica
Pictonum, by drinking Rain Water. It was at a Country-Seat, which
being situated too high to have the Advantage of a Well, was supply'd
with Water from a Tank, which received the Water from the leaded
Roofs. This had been drunk several Years without Mischief; but some
young Trees planted near the House growing up above the Roof, and
shedding the Leaves upon it, it was suppos'd that an Acid in those
Leaves had corroded the Lead they cover'd and furnished the Water
of that with its baneful Particles and Qualities."
Today's acid rain is not the only factor increasing lead contamination.
Researchers
at Dartmouth University found that certain chemicals being added to our
drinking
water are magnifying the uptake of lead and other toxic metals into the
body and
brain. Analyzing a major survey of more than 280,000 Massachusetts children,
the
team headed by Prof. Roger D. Masters has identified corrosive chemicals
widely
used in the fluoridation of public water supplies that apparently increase
children's
absorption of lead.
Fluoridation Increases Lead Uptake
The culprits are silicofluorides — fluosilicic acid and sodium silicofluoride
— the
chemicals used in more than 90% of America's fluoridated drinking water
systems.
In their study published in the October 1999 International Journal of
Environmental Studies, the Dartmouth researchers show that children's blood
lead is significantly higher in Massachusetts communities using silicofluorides
than in
towns where water is treated with sodium fluoride or not fluoridated at
all.
Compared to a matched group of 30 towns that do not use silicofluorides,
children
in 30 communities that use these chemicals were over twice as likely to
have more
than 10 ug/dL of lead in their blood.
"Silicofluorides are largely untested," Professor Masters explains. "Virtually
all
research on fluoridation safety has focused on sodium fluoride, even though
the
studies in the 1930s showed important biological differences between these
chemicals."
Since completing the Massachusetts study, the Dartmouth group further confirmed
the link between silicofluorides and elevated blood-lead levels — based
on data
from rural counties in six additional states, as well as from a survey
of more than
120,000 children in New York towns and from the Third National Health and
Nutrition Evaluation Survey (NHANES III).
History Repeats Itself
Just like the acidic leaves that leeched lead from the paint on that 18th
century roof,
fluosilicic acid leaches lead from plumbing. This was graphically demonstrated
in
two communities that stopped fluoridating their water systems. Their lead
levels
dropped significantly.
During a 1992 drought in Tacoma, Washington, they temporarily stopped
fluoridating their water and lead levels dropped from 32 ppb (parts per
billion) to
17 ppb. When Thurmont, Maryland stopped fluoridating their drinking water
in
1994, the lead level in homes dropped from 30 ppb to 7 ppb. (The EPA's
Maximum Contaminant Level is 15 ppb.) [13]
More than 98% of U.S. homes have lead in their plumbing systems. It comes
from
lead pipes, or copper pipes connected by lead solder, and from brass faucets,
which also contain lead . Most chrome plated faucets are made of brass
which is
permitted to contain as much as 8% lead.
Poisoning the Well — Lead, Drugs, and Violence
According to Prof. Masters, who heads the Dartmouth Foundation for
Neuroscience and Society, "Through one of several plausible mechanisms,
SiF
[silicofluoride] treated water can increase the transport of heavy metals
across the
gut-blood and blood-brain barriers, increasing rates of toxic uptake and
behavioral
disfunction."
On Sept. 2, 1999 at the Annual Conference of the Association for Politics
and the
Life Sciences, Prof. Masters gave the Plenary Address: "Poisoning the Well:
Neurotoxic Metals, Water Treatment, and Human Behavior." He said the problem
is especially serious because lead poisoning is associated with higher
rates of
learning disabilities, hyperactivity, substance abuse, and crime. Children
who have
been poisoned by lead are less able to handle stress and are more prone
to violent
outbursts.
Silicofluorides and Violence
Heavy metals damage neurons and "compromise normal brain development and
neurotransmitter function, leading to long-term deficits in learning and
social
behavior," says Masters. Lead blocks the action of calcium atoms in the
synthesis
of serotonin and dopamine, neurotransmitters essential to normal impulse
control
and the suppression of violent behavior.
Where silicofluorides were used to fluoridate water, risk-ratios for blood
lead over
10 ug/dL are from 1.25 to 2.5 — more than doubled. Silicofluorides are
thus
ultimately responsible for more aggressive behavior among people who consume
fluoridated water — including the soft drinks, juices, and foods made with
fluoridated water — and whose diets are lacking in calcium.
After an analysis of 129 rural communities in Georgia, Masters also found
that
"communities using silicofluorides also report higher rates of learning
disabilities,
ADHD, violent crime, and criminals who were using cocaine at the time of
arrest."
This makes sense because lead depresses dopamine levels in the brain, and
cocaine addiction is associated with low levels of dopamine.
An Old Story — Rome
Throughout history lead has been intimately related to plumbing. On the
periodic
table of elements, the symbol for lead is "Pb" — short for plumbum — the
Latin
word for plumbing. In ancient Italy magnificent aqueducts carried water
from the
mountains, supplying the people of Rome with 220 million gallons of water
per day.
Inside the city, water was distributed by lead pipes. The diameter of the
pipe
determined the cost of water, which flowed continuously. There were no
faucets.
The Romans also used lead to halt the fermentation of wines and to preserve
food.
Their drinking vessels and cookware were coated with lead glazes. (Ceramics
are
still a source of lead exposure in modern times.)
Evidence still exists of the Romans' huge lead mining operations two millennia
ago
in southwestern Spain. Researchers have detected lead concentrations in
core
samples taken from Greenland's ice, evidence of large-scale pollution of
Earth's
atmosphere that peaked between 150 B.C. and 50 A.D., the height of Roman
mining activity. "Lead pollution levels during the Roman era were about
four times
greater than natural background levels of lead but were still low by modern
standards. Between the 1930s and 1970s, the lead concentration in the ice
was 25
to 50-times higher than during Roman times, due in large part to leaded
gasoline."
[14]
Dr. Herbert L. Needleman, a leading researcher on the effects of low-level
lead
exposure, notes that the "increase in psychiatric disturbance in upper
class Romans
may have been related to lead exposure from plumbing and wine additives
and thus
was in part responsible for the decline of Rome." [15]
Tin cans sealed with lead were once a major source of contamination. In
the 1840s
a famous expedition trying to find the Northwest Passage became lost. More
than
140 years later their bodies were finally found. The entire group had been
poisoned
to death by the lead in their cans of food. First, sleeplessness and irrational
behavior overtook them. Then death came when the lead blocked the enzyme
responsible for hemoglobin production, and their kidneys failed.
Sources of Lead Exposure this Century
In "The Story of Lead," Peter Montague reports: "The period of greatest
lead use
was 1945-1971, after which it began to decline. In those years, 165,000
to
275,000 tons of lead dust spewed from the exhaust pipes of American automobiles
each year. Americans born during these years have 300 to 1000 times as
much
lead in their bodies as pre-Columbian indigenous people had. Thus the generation
of decision-makers in power today — in government and in corporations —
is
made up of people who are suffering mental irritability and dysfunction
as a result of
severe chronic lead insult. Reviewing the history of the past 25 years,
it seems clear
that the nation and the world have already paid a terrible price for their
irritability
and dysfunction. Leadership by the most lead-damaged (those born around
1970)
lies just ahead." [16]
The CDCP's 1998 study reported that the average concentration of lead in
all 20
million American preschoolers was 2.7 ug/dL, or 43 times as high as the
natural
background. [1] The 10 ug/dL now established as "safe" for children is
625 times
greater than the average lead level in the bodies of the pre-Columbian
inhabitants of
North America. [17]
The EPA permits our drinking water to have 15 ppb, but according to one
of their
own studies: "Drinking water supplied to 30 million people in 819 cities
contains
unhealthy levels of lead." [18]
"Cover the Earth"
In the United States, paint is now the chief source of the lead that poisons
children.
Leaded paint is still very common in older houses. More than 80% of U.S.
housing
built before 1980 contain some lead-based paints. In particular, white
paint used to
be made with lead carbonate and yellow paint from lead chromate.
Although lead and mercury, another toxic metal, are no longer allowed in
paint,
other chemicals continue their legacy. According to their labels, certain
paints
contain solvents that "can cause permanent brain and nervous system damage."
For
some strange reason, paint seems to be the delivery system of choice for
brain
damage. (Will future archeologists be baffled by a society whose walls
were more
vibrant than its brain cells?)
In October 1999, the state of Rhode Island sued eight of the nation's largest
paint
companies for marketing lead-based paints that are poisoning thousands
of
children. Atty. Gen. Sheldon Whitehouse said that nearly 20% of Rhode Island
children entering kindergarten had elevated lead levels, and "it's time
to force those
who made the mess to clean it up."
According to a report in The Providence Journal (Oct. 16), Whitehouse says
the
paint industry knew about the dangers of lead since the 1930s. He quotes
industry
officials in the 1950s who referred to lead poisoning as "mainly a problem
in the
slums and voicing more concerns over bad publicity than over the victims."
What's
worse, "paint company publicity extolled the health benefits and safety
of lead
paints."
Another source of lead is vinyl mini-blinds made in Asia and Mexico. Laboratory
tests show that when these particular mini-blinds deteriorate, their dust
contains
high levels of lead that can end up on children's hands and in their mouths.
Also,
candles with lead in their wicks have been shown to produce unhealthy levels
of
lead in the air for many hours — even after the candle is no longer burning.
Environmental lead exposure from industrial pollution and lead residues
in soil
further add to the accumulating burden of lead in the body and brain.
Getting the Lead Out
Oral or intravenous chelation therapy is the primary means for mobilizing
lead and
other heavy metals from the body, according to Dr. Walter J. Crinnion,
a
naturopathic physician who teaches environmental toxicity at Bastyr University
in
Seattle. Since 1987 he has operated the most comprehensive cleansing protocol
in
the nation and has found that "Diets high in the pectins and foods high
in sulfur
containing amino acids (methionine, cysteine) such as onions, garlic and
beans can
help. Sweating also helps to some extent." [4]
And, based on the 1999 Dartmouth study, it would be wise to avoid water
treated
with caustic fluoride compounds.
Ending the Violence of Lead
The time has come to acknowledge the real dangers of lead contamination.
Lead
threatens civility and compromises critical thinking — at the very time
when these
qualities are needed the most. Lead impairs our ability to distinguish
between
primitive impulse and intelligent action. Furthermore, its role in our
epidemic of
suicide and domestic violence has yet to be investigated.
Humankind has barely ascended from the gene pool of thoughtlessness where
reaction is the rule, and only by a slender thread does our humanity hang.
This
century, the human brain is being challenged by concentrations of lead
and other
heavy metals far beyond its evolutionary experience. The toxins we have
loosed
into the environment are corrosive to cognition and consciousness. By attacking
the
headquarters of our humanity, our priceless prefrontal cortex, they disintegrate
our
thin veneer of civilization — shredding that slender thread.
"This, my dear Friend, is all I can at present recollect on the Subject.
You will see by it, that the Opinion of this mischievous Effort from
Lead is at least above Sixty Years old; and you will observe with
Concern how long a useful Truth may be known and exist, before it is
generally receiv'd and practis'd on.
I am, ever, yours most affectionately, B. Franklin"
If he were here today, what would Benjamin Franklin say about the problem
of lead contamination? Click here to read an imaginative "interview" with
Dr. Franklin.
References
1. "Exposure of the U.S. Population to Lead, 1991-1994," Environmental
Health Perspectives, Nov. 1998
2. "Preventing lead poisoning in young children," Centers for Disease Control,
Oct.
1991
3. "Measuring lead exposure in infants, children, and other sensitive populations,"
National Research Council, 1993
4. Walter J. Crinnion, N.D., Doctors Health Review, Aug. 1999
5. Rachel's Environment & Health Weekly #633, Jan. 14, 1999
6. Tuthill, R.W., "Hair lead levels related to children's classroom attention-deficit
behavior," Arch Environ Health 1996 May-Jun;51(3):214-20
7. Minder, B., et al.,"Exposure to lead and specific attentional problems
in
schoolchildren," J Learn Disabil 1994 Jun-Jul;27(6):393-9
8. Brockel, B.J. & Cory-Slechta, D.A., "Lead, attention, and impulsive
behavior:
changes in a fixed-ratio waiting-for-reward paradigm," Pharmacol Biochem
Behav 1998 Jun;60(2):545-52
9. Reuters News Service, Feb. 11, 1999
10. Bressler, J., et al., Neurochem Res 1999 Apr;24(4):595-600
11. Zimmermann, H.P., et al., "Interaction of triethyl lead chloride with
microtubules in vitro and in mammalian cells," Exp Cell Res 1985
Jan;156(1):140-52, Faulstich, H., et al., "The molecular mechanism of interaction
of Et3Pb+ with tubulin," FEBS Lett 1984 Aug 20;174(1):128-31, Konat, G.,
"Triethyllead and cerebral development: an overview," Neurotoxicology 1984
Fall;5(3):87-96
12. Charles Gant, M.D., Ph.D., "Eat to Heal: New York Doctor Treats Attention
Deficit Disorder (ADD) with Nutrition," Holistic Health Journal, Autumn
1997
13. "Fluoride Banned in Thurmont, Maryland," Frederick Post, Feb. 3, 1994
and
Letter from Water Quality Coordinator, Tacoma Public Utilities to Washington
State Dept. of Health, Dec. 2, 1992 (Reported in Waste Not, Sept. 1998)
14. "Pollution of the Caesars," Discover, March 1998
15. "The Effects of Low Level Lead Exposure," Natural Resources Defense
Council, 1978
16. Rachel's Environment & Health Weekly #540, April 3, 1997
17. "Lead Levels in Preindustrial Humans," New England Journal of Medicine,
May 7, 1992
18. USA Today, May 12, 1993
Related Articles:
Moral behavior traced to specific brain area NEW YORK, Oct 19, 1999
Human genome could be mapped by June NEW YORK, Oct 14, 1999
(Reuters Health)
Marijuana-like substance in brain relieves pain NEW YORK, Oct 11, 1999
(Reuters Health)
Brain chemistry may explain addiction vulnerability NEW YORK, Sep 08, 1999
(Reuters Health)
A lead on why lead hurts the brain
Lead competes with calcium to bind to certain molecules in nerve cells,
which may explain why the
metal damages the nervous system.
References:
Bouton, C.M.L.S., et al. 1999. Synaptotagmin is a molecular target for
lead. Meeting of
the Society for Neuroscience. October. Miami Beach.
Sources:
Christopher M.L. Bouton
Johns Hopkins Medical Institutions
Department of Neurology
Department of Neuroscience
Baltimore, MD 21205
From Science News, Vol. 156, No. 19, November 6, 1999, p. 303. Copyright
© 1999, Science Service.
s e a r c h
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