Biomarker: a chemical, its metabolite, or the product of an
interaction between a chemical and some target molecule or cell
that is measured in the human body.
Environmental monitoring: the measurement of a contaminant's
concentration in a medium (e.g., air, soil, water, or food).
Human biomonitoring: the direct measurement of people's
exposure to toxic substances in the environment by measuring the
substances or their metabolites in human specimens, such as
blood or urine.