Unité d’évaluation des risques sanitaires Direction des risques chroniques Institut national de l’environnement industriel et des risques (Ineris) Parc technologique Alata BP 2 60550 Verneuil-en-Halatte France
A review of the literature was conducted to enable us to describe the current state of knowledge about human exposure in the workplace to endotoxins. These extracellular lipopolysaccharides of Gram-negative bacteria are well known for inducing respiratory symptoms in humans exposed by inhalation (inflammatory, toxicological and immunological mechanisms). The occupational settings most often studied are animal breeding facilities, the wood industry, waste-handling facilities, composting sites and sewage treatment plants. Overall, endotoxin measurement data are scarce. The highest endotoxin concentrations found in our review were in animal and in grain/vegetable storage sites. Human exposure to endotoxins is governed by a number of specific characteristics, and concentrations vary substantially. This may explain the lack of an internationally established exposure threshold, although some countries, such as the Netherlands have already proposed national values (5 ng/m
3 for an 8-hour work exposure). Finally, environmental exposures have been studied very little, and no air quality guidelines are available for the general population. Health risks for sensitive populations and/or indoor environments are not well understood. In view of the size of the populations exposed to endotoxins and of the seriousness of the health effects, air quality guidelines are badly needed. The health-based threshold value proposed by the Netherlands can be considered for occupational exposure. An air measurement standard is needed as well as on-site measurement campaigns to improve the characterization of environmental exposure.