[Biological monitoring at the work site].

Exposure to industrial chemicals is assessed by ambient monitoring (external exposure/dose), by health surveillance (detection of adverse biological/health effects in exposed workers) and by biological monitoring (evaluation of the internal exposure of the organism to a chemical agent). Objectives, principal advantages and limitations of biological monitoring are discussed; the programs of biological monitoring as a part of the health surveillance of Swiss workers guided by the Swiss National Accident Insurance Fund are briefly summarized.