Respiratory function in tea workers.

Respiratory function was studied in five groups of tea workers employed in processing different types of tea. The prevalence of almost all chronic respiratory symptoms was significantly higher in workers processing dog-rose, sage, and gruzyan tea than in control workers. During the Monday workshift there was a significant mean acute decrease in maximum expiratory flow rates at 50% vital capacity (range: 4.1-8.8%) and at 25% VC (range: 7.8-21.8%) except in those exposed to camomile. Acute reductions in forced expiratory volume in one second were considerably smaller and mostly not significant. Mean acute reductions on Wednesday were similar to those on Monday with no significant differences between preshift Monday and Wednesday data. Acute decreases in flow rates at low lung volumes suggest that the bronchoconstrictor effect of the dust acts mostly on smaller airways. Preshift administration of disodium cromoglycate significantly diminished acute reduction in flow rates except in workers processing Indian tea. A comparison of Monday preshift values of ventilatory capacity in tea workers with those in controls indicates that exposure to tea dust may, in some workers, lead to chronic respiratory impairment.