EFFECTS OF SMOKING AND OCCUPATIONAL EXPOSURE ON PERIPHERAL AIRWAY FUNCTION IN YOUNG CEREAL GRAIN WORKERS

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Abstract
Two groups of young male cereal grain elevator workers: 82 lifetime nonsmoking grain workers (2.5 .+-. 2.3 yr of dust exposure) who were 22.7 .+-. 3.5 yr of age, and 82 smoking grain workers (6.1 .+-. 4.1 pack-yr of smoking) individually matched to the nonsmoking grain workers for age (22.7 .+-. 3.3 yr) and yr of work in the grain industry (2.6 .+-. 1.3 yr) were studied. The following groups of community control subjects: 82 nonsmoking community control subjects individually matched to the nonsmoking grain workers or age (22.8 .+-. 3.7 yr), and 82 smoking community control subjects individually matched to the smoking grain workers for age (22.7 .+-. 3.6 yr) and smoking history (6.0 .+-. 4.0 pack-yr) were studied. Forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), FEV1/FVC%, the maximal mid-expiratory flow rate (FEF28-75), the flow at 50% (.ovrhdot.Vmax50) and 25% (.ovrhdot.Vmax25) of a maximal expiratory flow-volume maneuver, the percent increase in the maximal expiratory flow at 50% FVC breathing a mixture of 80% He-20% O as compared with air (.DELTA..ovrhdot.Vmax50), and the slope of phase 3 of the single breath nitrogen test (.DELTA.N2/L) were also measured. The prevalence of respiratory symptoms from responses to a standardized questionnaire were assessed. Smoking was associated with an increased prevalence of cough, wheezing and dyspnea, and a mildly decreased FEV1/FVC%. Two variables were used as indexes of small airway dysfunction, a lower .DELTA..ovrhdot.Vmax50 and a higher .DELTA.N2/L. Only the group of workers who smoked and were occupationally exposed to grain dust had evidence of small airway dysfunction. The differences in .DELTA.N2/L and .DELTA..ovrhdot.Vmax50 were greater than was expected from an additive model, suggesting that the combined effects of occupational exposure to grain dust and inhalation of cigarette smoke may have had a synergistic effect leading to small airway dysfunction in young cereal grain workers.