The Use of Biomarkers in Hazard Assessment

Abstract

Definitions of biomarkers have varied considerably and have been frequently so broad as to include any biological change caused by chemical agents. Recently the concept that this term should be restricted to organisational levels of the intact organism and below has gained support. On this basis biomarkers can be defined as “any biological response to an environmental chemical at the individual level or below demonstrating a departure from normal status”. Changes at organisational levels above that of the individual are referred to as bioindicators. Biomarkers have the advantage over chemical analysis in that they can demonstrate whether or not an organism is meaningfully exposed. Analytical chemistry is now so sophisticated that many pollutants, especially the organochlorines, can be detected in almost all samples. But unless the biological significance of chemical residues is known, this information is of very limited value. With biomarkers, it is possible to determine if the physiology of the organism is significantly different from normal. If the parameter measured is outside the normal physiology range for that species, then the organism can be considered to be meaningfully exposed, and equally importantly, if the physiology is not significantly different, then the organism can be considered not to be meaningfully exposed even though the chemical(s) can be detected. The ability to determine whether or not an organism is meaningfully exposed is important in the decision-making process about the necessity or success of remedial action.