AND EXAMPLES
 Hazardous, or toxic, waste is the potentiallydangerous byproduct of a
wide range of activities, including manufacturing, farming, water
treatment systems, construction, automotive garages, laboratories,
hospitals, and other industries. The waste may be liquid, solid, or sludge
and contain chemicals, heavy metals, radiation, pathogens, or other
materials. Even households generate hazardous waste, from items such
as batteries, used computer equipment, and leftover paints or
pesticides.
 Mercury is a chemical element with the symbol Hg and atomic number 80. It is also
known as quicksilver and was formerly named hydrargyrum from the Greek
words hydro (water) and argyrols (silver). A heavy, silvery d-block element, mercury is
the only metallic element that is known to be liquid at standard temperature and
pressure; the only other element that is liquid under these conditions is
the halogen bromine, though metals such as cesium, gallium, and rubidium melt just
above room temperature.
 Mercury occurs in deposits throughout the world mostly as cinnabar (mercuric sulfide).
The red pigment vermilion is obtained by grinding natural cinnabar or synthetic
mercuric sulfide.
 Arsenic is highly toxic in its inorganic form. Contaminated water
used for drinking, food preparation and irrigation of food crops
poses the greatest threat to public health from arsenic. Longterm exposure to arsenic from drinking-water.
 Arsenic is a chemical element with the symbol AS and atomic
number 33. Arsenic occurs in many minerals, usually in
combination with sulfur and metals, but also as a pure
elemental crystal. Arsenic is a metalloid. It has various allotropes,
but only the gray form, which has a metallic appearance, is
important to industry. food can cause cancer and skin lesions.
Lead is a chemical element with the symbol Pb and atomic
number 82. It is a heavy metal that is denser than most
common materials. Lead is soft and malleable, and also
has a relatively low melting point. When freshly cut, lead is
a shiny gray with a hint of blue. It tarnishes to a dull gray
color when exposed to air. Lead has the highest atomic
number of any stable element and three of its isotopes are
endpoints of major nuclear decay chains of heavier
elements. Lead is toxic, even in small amounts, especially
to children.