Uses of biochemical and biological markers in occupational epidemiology.

The use of biochemical or biological markers is increasing in cancer epidemiology, but the rationale for their introduction is not always clear, i.e. it has not been established when and how their use is scientifically justifiable, ethically correct and cost-effective. There is an entire range of indications for biomarkers, from the use of very specific measurements aimed at single molecules, to measurements indicating cumulative exposure to agents with the same mechanism of action. The following are some potential uses of markers in occupational epidemiology: 1) exposure assessment in cases in which traditional epidemiologic tools are insufficient (particularly for low doses and low risks; 2) multiple exposures or mixtures, in which the aim is to disentangle the etiologic role of single agents; 3) estimation of the total burden of exposure to chemicals having the same mechanistic target; 4) investigation of pathogenetic mechanisms; 5) study of individual susceptibility (e.g. metabolic polymorphism, DNA repair). Examples are discussed together with methodological limitations.