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Arsenic
Arsenic is released into the environment through
production of copper, zinc, lead, chemicals and glasses.
Arsenic is found in water supplies worldwide, leading to
exposure of shellfish, cod, and haddock. Other sources
are paints, rat poisoning, fungicides, and wood
preservatives. The target organs for arsenic are the
blood, kidneys, central nervous system, digestive system
and skin.
Lead
Lead is a very soft metal and was used in pipes, drains,
and soldering materials for many years. Millions of
homes built before 1940 still contain lead leading to
chronic exposure. Industry produces about 2.5 million
tons of lead annually. Most of this lead is used for
batteries. The remainder is used for cable coverings,
plumbing, ammunition, fuel additives, paint pigments,
PVC plastics, x-ray shielding, crystal glass production,
pencils and pesticides. The target organs are the bones,
brain, blood, kidneys, and thyroid gland.
Mercury
Mercury exists in three forms: elemental mercury,
organic and inorganic mercury. Mining operations,
chloralkali plants and paper industries are significant
producers of mercury. Atmospheric mercury accumulates in
aquatic food chains contaminating fish. Mercury
continues to be used in thermometers, thermostats,
dental amalgam fillings and vaccines. Inhalation is the
most frequent route of exposure to mercury. The organic
form is readily absorbed in the gastrointestinal tract
(90-100%); lesser but still significant amounts of
inorganic mercury are absorbed in the gastrointestinal
tract (7-15%). The target organs are the brain and
kidneys.
Cadmium
Cadmium is a byproduct of the mining and smelting of
lead and zinc. It is used in nickel-cadmium batteries,
PVC plastics and paint pigments. Insecticides,
fungicides, sludge and commercial fertilizers that use
cadmium contaminate farmland. Cigarettes also contain
cadmium. Lesser-known sources of exposure are dental
alloys, electroplating, motor oil and exhaust. The
target organs are the liver, placenta, kidneys, lungs,
brain and bones.
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