Respiratory effects of inhaled isocyanates

Numerous industrial chemicals are known to cause allergic reactions in the lung. Prominent among such chemicals are isocyanates, the starting material in the production of polyurethanes. In view of the extensive worldwide production of isocyanates (1.5 million metric tons per year), and the diversity of products manufactured from isocyanates (i.e., cars, airplanes, furniture, bedding, etc.) there is considerable potential for adverse health effects associated with exposure to isocyanates. Syndromes of immediate respiratory reactivity, delayed-onset sensitivity, and hypersensitivity pneumonitis have all been associated with isocyanate exposure. However, little is known concerning how sensitivity develops, which individuals are most likely to become sensitized, or how to best detect early sensitivity. Answers to such questions are beginning to emerge from the recent development of animal models of lung sensitivity. These models will be discussed together with their application to clinical situations.