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. Sometimes also called 'biomonitoring'.
Source:
PAC, 2001, 73, 993. 'Risk assessment for occupational exposure to chemicals. A review of current methodology (IUPAC Technical Report)' on page 1021 (https://doi.org/10.1351/pac200173060993)