The environment in which we claim to "live" in has become a huge
reservoir of toxic metals. Human health is under constant risk of deterioration due
to increasing chronic exposure of such metals that adversely affect the quality of
life of people. The expedition to meet man's basic need for food, clothing and
shelter has continually heightened pollution of the biosphere. The deterioration of
human health due to exposure to heavy metals has become a major issue of
concern worldwide. Although adverse health effects caused by heavy metals have
been known for a long time, exposure to heavy metals continues, and is even
increasing in some parts of the world, particularly in less developed countries,
even though emissions have declined in most developed countries over the last
100 years.
The term "heavy metals" refers to any metallic element that has a
relatively high density and is toxic or poisonous even at low concentration [1].
"Heavy metals" is a general collective term, which applies to the group of metals
and metalloids with atomic density greater than 4 g/cm3, or 5 times or more,
greater than water [2]. Heavy metals include lead (Pb), cadmium (Cd), zinc (Zn),
mercury (Hg), arsenic (As), silver (Ag) chromium (Cr), copper (Cu) iron (Fe), and
the platinum group elements [3]. Heavy metal toxicity is the excess of
concentration of toxic heavy metals which have become concentrated as a result
of human caused activities, enter in plant, animal and human tissues via
inhalation, diet and manual handling, and can bind to, and interfere with the
functioning of vital cellular components.
