OVERVIEW OF DIISOCYANATE OCCUPATIONAL ASTHMA

Surveillance programs established around the world have determined tha t diisocyanate chemicals are the most common cause of occupational ast hma. In the United States approximately 100 000 workers are exposed to these chemical compounds in the workplace each year and 5-10% of thes e workers will develop occupational asthma. There are no known reliabl e risk factors or biomarkers which can be used to predict which expose d worker will develop diisocyanate-occupatonal asthma. Diisocyanate-oc cupational asthma workers manifest characteristic physiologic response s after specific bronochoprovocation which correlate with pathologic c hanges in their airways. However, the mechanism(s) for diiocyanate-occ upational asthma remains unclear. Specific IgE antibody production to diisocyanates is found in only 10-30% of these workers. Bronchial biop sies and bronchoalveolar lavage have confirmed the presence of T-lymph ocytes and eosinophils in the airways of these workers suggesting that T-cell mediated immune responses are more likely to play a central ro le in this disease. It is essential to diagnose diisocyanate-occupatio nal asthma as early as possible in order to prevent or reduce the sign ificant asthma morbidity associated with continuous long term exposure to these chemicals. Treatment of choice is removal of the worker from further exposure. Prospective studies evaluating larger populations o f diisocyanate-exposed workers is essential for a better understanding of the pathogenesis and natural course of diisocyanate-occupational a sthma.