الفهرس 
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Abstract
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Pollution is the price of maintaining and improving our standard of living.
Many noxious and toxic chemical substances, natural and synthetic, are involved
in processing raw materials, in manufacturing fmished goods, and in providing
essential services. Pollutants are thus direct products or indirect by-products of our
technologic processes.
Pollution is the most serious of all environmental problems and poses a
major threat to the health and well-being of millions of people and global
ecosystems. Other major environmental problems are either wholly or partly
caused by pollution; these include global warming, climatic change and the loss
ofbiodiversity through the extinction of many species. In the future, environmental
pressures can only increase as a result of population growth and the expectation
of higher living standards (AlIoway and Ayres, 1993).
Pollutants from different sources are introduced to the environment so that
it is seldom are we exposed to a single pollutant. Significantly exposure to
combinations of pollutants may produce different effects from those that would
result from exposure to each pollutant separately. The combined effect may be
purely additive, synergistic, antagonistic or potentiative-interactions that determine
the consequences of simultaneous exposure and thus the maximum permissible
concentration of pollutants coexisting in a particular environment (Slonim, 1974).