A parameter that can be used to identify a toxic effect in an individual organism and can be used in extrapolation between species, or as an indicator signalling an event or condition in a biological system or sample and giving a measure of exposure, effect, or susceptibility. The term 'biomarker' is generally used in scientific publications. In occupational hygiene and health, 'biological monitoring' and 'biological effect monitoring' are used with the meaning 'monitoring biomarkers'.