Handling of household waste exposes an increasing number of workers to an organic dust of a high complexity. A European Union funded collaborative project comprising nine laboratories has the goal to define risks for disease among workers exposed to dust from waste. Exposure assessment studies will evaluate the viable microbial and the cell wall component exposure in relation to different technical procedures for storing and processing of waste. Epidemiological studies will be performed on exposed workers engaged in various work processes with particular reference to the role of airways inflammation and asthma. Challenge studies will be performed to study inflammation and to determine no observed effect level for inhaled endotoxin. Animal experiments will evaluate the role of endotoxin and (1 3)-b-D-glucan for the development of airways inflammation.