Organic dusts and lung reactions--exposure characteristics and mechanisms for disease.

Exposure to organic dusts has been related to pulmonary occupational diseases in a variety of environments. These dusts contain several different agents, but the microbial contamination is always important, particularly regarding molds and Gram-negative bacteria. In the lung, organic dusts cause a series of reactions ranging from irritation with neutrophilic invasion to the initiation of cell mediator release and the development of antibodies. For certain diseases, such as byssinosis, the relation between the cell reactions and the disease is relatively well established; for others, such as allergic alveolitis (hypersensitivity pneumonitis) with fibrosis, more research is needed before the pathogenesis can be established. An understanding of the specific agents causing the disease and the cellular reactions behind its development is essential for its prevention.