ABSTRACT
This chapter presents three basic approaches to classifying hazardous wastes: a qualitative description by origin, type, and constituents; classification by characteristics largely based upon testing procedures; and by means of concentrations of specific hazardous substances. Legislation and regulations dealing with wastes often go to great pains to distinguish between hazardous and nonhazardous wastes. In reality, the distinction is blurred. Often, too, nonhazardous materials may interact with hazardous ones in ways that increase their threat to the environment or human welfare. Hazardous substances come in a wide variety of forms and formulations. These include gases, liquids, and solids. Although the chemical variability of hazardous substances make such a classification system somewhat inexact, several categories can be defined based upon chemical behavior. These are the following: combustion hazards, oxidizers, reactive substances, and corrosive substances. By their nature, air and water pollutants tend to be toxic, corrosive, or otherwise dangerous to health or the environment.
