kahjulike ainete sisalduse regulaarne mõõtmine keskkonnas ja bioloogilistes objektides, selgitamaks välja riski inimesele ja keskkonnale, continuous or repeated measurement of potentially toxic substances or their metabolites in tissues, secreta, excreta, expired air, or any combination of these to evaluate occupational or environmental exposure and health risk by comparison with appropriate reference values based on knowledge of the probable relationship between ambient exposure and resultant health effects
