4.1 Entry Characterization
Entry characterization involves identifying where and how a substance may enter or has entered the environment (e.g., through natural occurrence, via industrial processes, or in consumer products) and the characterization of releases from these processes (e.g., quantities, frequency, and duration). This information is critical for determining the relative significance of a source of release and the scale (in terms of both time and space) of potential exposures. Understanding where a substance enters the environment (e.g., whether it is released to water or to air) is also essential for determining its fate in the environment.

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