A measured environmental concentration (MEC) is the amount of a chemical substance found in an environmental sample. The concentration of the compound may result from direct contamination, the transformation or metabolization of a different chemical contaminant, natural origin, or a combination of these sources. MEC is to be used as a reference in the context of Chemical Safety Assessments (CSA) and should be compared with the respective Predicted Environmental Concentration (PEC) and Predicted No-Effect Concentration (PNEC) in order to decide whether exposure model is valid and the compound related risk is controlled. The formula: Risk = Measured environmental concentration/Predicted no-effect concentration is used to calculate risk information.
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