Among the objectives of epidemiological surveillance, priority is sometimes given to acquiring knowledge rather than to detecting clusters of cases, which is the primary purpose of surveillance designed to provide early warning. When applied to the field of environmental health, epidemiological surveillance relies on traditional methods, all of which involve a phase of repeated data collection: surveillance systems and repeated cross-sectional surveys. However, the complexity of the interactions between exposure and its health effects (long latency period between exposure to environmental pollutants and the onset of health events, low proportion of attributable risk, and low exposure levels) dictates how this surveillance is implemented. In practice, few systems directly monitor health effects linked to environmental exposure (carbon monoxide poisoning). Most systems implemented in the field of environmental health have had to address this challenge by conducting surveillance on environmental media (air) or using biomarkers as indicators of exposure (lead poisoning) or early effects of exposure. Recent developments in the field reflect the direction taken with the increased use of biomarkers within the InVS biomonitoring program, the growing reliance on multi-objective studies based on shared resources (Saturninf, National Nutrition and Health Study (ENNS)), or the integration of surveillance from the outset of major research projects such as the Elfe cohort (French Longitudinal Study from Childhood). (R.A.)