Validated biological monitoring methods are used in large-scale monitoring programmes involving determination of ubiquitous environmental pollutants such as metals and pesticides. Some programmes focus on children's exposure, and policies to prevent adverse health effects. Most of these initiatives are aimed at characterizing trends. Some of these programmes are designed to investigate the role of certain exposures in disease. Fewer new biological monitoring methods were presented during the present meeting than in previous meetings. All of these new methods used mass spectrometric-based detection and quantification. There is an increasing use of biomarkers to study genetic polymorphisms of enzyme systems involved in both toxification pathways and metabolite conjugation and DNA repair. At the meeting a discussion was started that could lead to a further harmonization of the scientific fundaments of the use of biological monitoring in occupational health with possible value also for applications in the field of environmental health.