RESPIRATORY FINDINGS IN WORKERS EMPLOYED IN THE BRICK-MANUFACTURING INDUSTRY

We studied 233 male workers employed in two brick-manufacturing plants and 149 matched control workers. The mean age of the brick workers wa s 35 years, with cc mean duration of employment in this industry of 16 years. The prevalence chronic respiratory symptoms as well as acute s ymptoms during the work shift were recorded. Lung-function was measure d on Monday during the work shift by recording maximum expiratory flow -volume (MEFV) curves, from which. the forced vital capacity (FVC), ti e one-second forced expiratory volume (FEV1) and flow rates at 50 % an d the last 75 % of the FVC (FEF50, FEF75) were measured. The results o f periodic chest roentgenograms were reviewed. There was a significant ly higher prevalence of chronic cough (31.8%), chronic phlegm (26.2%), and chest tightness (24.0%) in exposed workers, compared with control workers (20.1%; 18.1%; 0%) (P < 0.05). This increased symptom frequenc y was also documented among nonsmokers studied by age and by length of employment, suggesting a work-related effect. Among work shift-relate d symptoms, high prevalences were noted for upper respiratory tract sy mptoms leg, dr: throat, eye irritation, throat irritation). The measur ed FVC and FEV1 were significantly lower than predicted for brick work ers and suggested a restrictive pattern. The mean FVC las a percent of predicted) was 78.1 % and FEV1 were significantly lower than predicte d for brick workers and suggested a restrictive pattern. The mean FVC (as a percent of predicted) was 78.1 % and FEV1 was 88.1%. The FEF50 a nd FEF25 were not significantly decreased. A multiple regression analy sis with age, exposure, and smoking as predictors and lung function pa rameters as response variables showed a significant effect between exp osure and FVC. Significant chest roentgenographic abnormalities were n ot documented. These findings of a restrictive lung function pattern i n brick workers with normal chest roentgenograms may suggest early int erstitial disease. Additionally, a bronchitic component, as suggested by the respiratory symptoms, may also be present.