Pollution Effects of solvents

The problem of toxic pollutants is difficult to handle because of the great variety of chemicals involved. They represent a hazard not only to aquatic life, but also to human health, either through direct exposure or indirectly through consumption of contaminated fish or waterfowl. The degree of hazard depends on the pollutanf s toxicity, rate of discharge, persistence and distribution in the aquatic system, and bioaccumulation potential. Some highly volatile compounds, when discharged into water, evaporate and become air pollutants. 

The health risk cannot be well defined because very little information is available on the toxicity of most commercial chemicals (Postel, 1987). According to the data published in 1984 by the National Research Council (National Research Council, 1984), very little is known about the toxicity of approximately 79% of commercial chemicals. Fewer than 10% were examined for carcinogenicity, mutagenicity, and reproductive toxicity (National Research Council, 1984). Obviously, nothing is known about pollutants that are byproducts of industrial processes and were never intended for commercial use. 

Spent solvents constitute a major source of pollution in the chemical and pharmaceutical industries. Much of this pollution can be prevented by solvent substitution using solvents that are more environmentally compatible or possess higher performance. This can lead to a reduction in the amount used. However, identifying replacement solvents is often a difficult process performed in an ad hoc manner. 

In industrialized countries, the sources of water pollution may be divided into point and nonpoint sources. Point sources have a well-defined origin, such as the outlet from a plant or from a municipal sewer line. Nonpoint sources lack any well-defined point of origin. 

Although both types of pollution sources present a serious problem, point sources can be controlled, at least in principle. Nonpoint sources, however, are difficult to control. Sources and types of nonpoint pollution in impacted rivers and lakes in the United States include agriculture, land disposal, construction, hydromodification, urban runoff, and silviculture, resource extraction. The pollutants in these sources include sediment, nutrients, toxins, pesticides, salinity, and acidity (Institute, 1988). Looking at these lists, one can easily deduce that solvents play roles in the pollution of water. 

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