ABSTRACT
I. CHARACTERISTICS OF ENVIRONMENTAL CONTAMINANTS There are literally thousands of substances that can contaminate the environment. In some cases, this contamination is related to natural conditions and is thus a “ background” condi tion. Most often, however, environmental contaminants are related to human activity. Current regulatory programs governing contaminated sites generally focus on a class of contaminants called hazardous substances. These regulated substances have been identified by the United States Environmental Protection Agency (USEPA) on the basis of their relative toxicity in the environment. Many other substances may be released to the environment; some are unregu lated, and others may be regulated by agencies other than the USEPA.
