Biological monitoring

Biological monitoring is the measurement in the workers' body of biological markers (biomarkers) related to occupational exposures. Exposure biomarkers are concentrations of exposure substances in human tissues, cells, or fluids. Examples are blood lead concentrations, pesticide metabolites in urine, and solvent concentrations in exhaled breath. Other biomarkers may be defined as biochemical alterations or responses to exposures, or indicators of host susceptibility. Workers exposed to certain chemical agents (for example, lead) should undergo routine biological monitoring to measure the levels of the original substance, their metabolites or related measurable changes in biological samples. Systematic information from biological monitoring of workers populations can be used for occupational epidemiology research. However, although the use of biomarkers has opened a new promising field for epidemiology, constraints of this approach should be noticed. Knowledge on biomarker distributions in general populations and on inter-individual and intra-individual variability is often limited. On the other hand, for many exposures there are not available valid or applicable biomarkers.