Biomonitoring in occupational health: scientific, socio-ethical, and regulatory issues

Biomonitoring is one of the best available tools for the prevention of deleterious effects resulting from occupational exposure to chemicals. The availability of analytical techniques having low detection limits allows for the measurement of numerous biomarkers. Complemented with quality control programs, our ability to collect validated information on exposure to toxicants improves. This is important as exposure doses tend to decrease in workplaces. Concurrently, there is an increasing preoccupation towards skin exposure, which cannot currently be reliably assessed through external measurements. Furthermore, as lower exposure doses are encountered, background concentrations of some biomarkers become a serious limitation to their use. This prompts researchers to seek for minor, more specific metabolites, that may however be produced through metabolic pathways that are prone to larger inter-individual variations. Assessment of exposure to complex mixtures of chemicals is another major challenge. There is a growing interest towards ethical issues in biomonitoring. The understanding of the advantages and of the limits of this preventive approach may be very different among occupational health professionals, but more importantly, between health professionals and those they are seeking to protect, i.e., the workers themselves. Many organizations have proposed guideline values for biomarker concentrations, but these seldom find their way in the various countries' bylaws. One underlying reason might be the greater complexity of the scientific aspects of biomarkers, whose understanding is required to set limit values, compared to the process of setting airborne limit concentrations. But the fact that the latter does not consider all aspects of biological complexity does not make it more reliable.