CHRONIC AND ACUTE RESPIRATORY EFFECTS AMONG GRAIN MILL WORKERS

Exposure to flour dust may induce chronic respiratory manifestations a s well as acute ventilatory effects. We compared the prevalence of res piratory symptoms, ventilatory impairment, and variations in pulmonary function over the workshift in a group of mill workers exposed to whe at flour and in referent workers. One hundred and forty-two men expose d to flour in a mill and 37 referent workers were included in this stu dy. Each subject completed a standardized questionnaire. Pulmonary fun ction tests were performed before and after the workshift. The assessm ent of environmental exposure to flour showed high concentrations duri ng some jobs with a high percentage of inhalable particles and a low c oncentration of respirable particles. The exposed workers had a signif icantly higher prevalence of usual cough and usual phlegm than the ref erents. The prevalence of asthma, based on the questionnaire, was simi lar. Before the workshift, the exposed workers had significantly lower mean lung function values for peak flow rate and forced expiratory fl ow rate at 75% of the vital capacity than the referents. After the wor kshift, all the lung function values showed a slight decrease, signifi cant for forced vital capacity and forced expiratory volume during 1 s in both groups. Among the exposed workers, the asthmatic subjects had a significantly higher decrease across the shift than the nonasthmati c workers. This result is probably linked to bronchial hyperreactivity . Among nonasthmatic subjects, the decrease was larger in nonexposed w orkers than in exposed workers. A higher prevalence of respiratory sym ptoms and lower pulmonary function values were observed among mill wor kers by comparison with referents. Moreover, the data suggest that ast hmatic status and the time of spirometric measurements need to be take n into account in epidemiological studies on exposure to airborne alle rgens. In addition, the study does not exclude a healthy worker effect with selection of dust-resistant subjects or better identification of asthmatic subjects among the workers exposed to an allergenic substan ce than among the nonexposed workers.