Respiratory variables and exposure-effect relationships in isocyanate-exposed workers.

Respiratory variables in 95 isocyanate workers and 37 control workers were compared. The exposed workers had a slightly higher frequency of cough and shortness of breath than the controls and a significantly lower frequency of family history of asthma, hay fever, and bronchitis. The isocyanate workers had slightly lower baseline lung function than the control workers but demonstrated significantly larger declines in their pulmonary function over the work shift. Both groups showed some intraday and intraweek variation in lung function. The changes in lung function over the work shift varied with different job categories, the largest changes occurring in finishing-area workers. A gradation of response was observed when exposure was categorized as nil, low, or high, but no exposure-effect relationships could be demonstrated by regression analysis of either area or personal results.