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Glossary
of Terms
Lead
Symbol: Pb
Atomic Number: 82
Somewhere between
400,000 and 600,000 tons of lead per
year go into our atmosphere, onto
our earth, into our food, and into
our body and tissues. Unlike most
chemicals for which the health impacts
of low-level exposure are still uncertain,
exposure to lead, even at very low
levels, is very toxic.
Lead is the most
common toxic mineral as well as being
the most abundant contaminant of our
environment and our body. Fortunately,
lead is not the most toxic element;
cadmium and mercury are worse. Lead
has a slightly sweet taste and children
often eat or suck on the paint chips
from houses leading to many cases
of lead poisoning.
The most widespread
source of environmental contamination
is from the addition of tetraethyl
lead to gasoline as an anti-knock,
higher-octane additive. Research has
shown that lead is a neurotoxin and
commonly generates abnormal brain
and nerve function. It enters the
brain and can, in pregnant or lactating
mothers, contaminate the in utero
fetus and breast milk.
Lead is commonly
stored in the bones as shown by "lead
lines" in the bones on X-rays.
It is also stored in the adrenals,
thyroid, aorta, liver and other soft
tissues.
In just the United
States, it has been estimated that
approximately 1.3 million tons of
lead is used yearly in solder, batteries,
pottery, pigments, gasoline, paint,
and many other useful substances.
Other sources of lead contamination
are lead industries, mining, and smelting,
piping, fixtures, insecticides and
solder. Due to its unique properties,
it has been used widely as a pigment
and drying agent in primers, paints
and enamels, inks, oils, resins, and
other surface coatings for centuries.
In drinking water, the major source
of lead is from the corrosion of leaded
plumbing materials in the water supply
and household distribution systems.
Lead most likely
interferes with functions performed
by essential minerals such as calcium,
copper and zinc. In the human system,
lead interrupts several red blood
cell enzyme systems, including delta-aminolevulinic
dehydratase and ferrochelatase. It
may also reduce hemoglobin synthesis
and can react with cell membranes.
This may cause increased permeability
of the cells and cause damage to or
even death of those cells. In the
brain, lead may create abnormal function
by inactivating important zinc-, copper-,
and iron-dependent enzymes.
The term lead comes
from the Latin word plumbum (lead).
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