Any disturbance in the natural cycle creates ecological imbalance which is the root cause of environmental pollution. Thus pollution may be defined as man-induced changes leading to deterioration in the quality of natural environment.
It is a by-product of man's actions through direct or indirect effects of changes in energy patterns, radiation levels, chemical and physical constitution and the abundance of organisms (Report, 1965). R.F. Dassmann (1975) has defined pollution as "the accumulation of substances, or forms of energy, in the environment in the quantities, or at rates of flow, which exceed the capacity of ecosystems to either neutralize or disperse them to harmless levels."
The air, water, soil, sunshine, minerals and animals, etc., are natural resources of the earth and their unscientific extraction, use and disposal by man modify the natural cycle so as to add a composite which the ecosystem is not able to recycle easily (Tiwari and Yadav, 1983, p. 62). During the last 150-200 years due to technological revolution man is recklessly using up the earth's limited non-renewable resources and destroying the vitals of the earth by reducing its remarkable capacity of regeneration.
According to an estimate 'the production of metals since the beginning of the Second World War has exceeded all the production in the whole history of the world up to that time' (Harvey and Hailet, 1977, p. 39). The new technology has given birth to two groups of materials: the synthetics and the composites which pose problems of disposal and recycling. Studies have shown that environmental pollution is growing at exponential rate even higher than the rate of population growth.
In India also due to rapid urbanization and industrialisation, particularly after Independence, the menace of environmental pollution has adversely affected the quality of our natural environment. Among the major sources of pollution concerning human health, the air, water, and soil are important ones.