[Respiratory pathology of isocyanates]

Isocyanates are chemical compounds used in making polyurethane (for flexible or rigid foam, paint, varnish, glue and textiles). In strong concentrations isocyanates are powerful irritants producing chemical bronchopulmonary lesions. In weak doses they are responsible for occupational asthma and more rarely allergic alveolitis. Long term exposure to isocyanates may produce a deterioration in pulmonary function in asymptomatic patients. The pathophysiology of isocyanate asthma remains uncertain: immunological data remains contradictory while isocyanates have been shown to have a Betablocking effect. The maximum allowable concentration in the working environment, at present proposed in the U.S.A. is 0.005 ppm.