The Relationship of Acute Respiratory Response and Chronic Respiratory Symptoms in Byssinosis

¹ From the School of Medicine, University of North Carolina at Chapel Hill
² From the Southern Regional Research Center, US Dept of Agriculture, New Orleans
³ Cotton, Inc., Raleigh, NC
⁴ From the School of Public Health, University of North Carolina at Chapel Hill

Workers from cotton textile mills were exposed for one hour to uniform concentrations of cotton dust in an experimental chamber. The responses monitored included subjective respiratory complaints and ventilatory (spirometric) variables. The dustiness ranged between 0.3 and 2.0 mg/m³ of air. Values were processed for all 32 subjects.

The clinical classification (ie, symptoms) of these subjects included four asymptomatic individuals who did not report respiratory complaints against the dustiness experienced at work; 13 persons with chronic bronchitis, all denying respiratory complaints referable to dustiness experienced at work; and 15 subjects with a symptomcomplex classified as byssinosis.

Response to provocative tests was monitored by either subjective respiratory complaint during exposure, by ventilatory deflection in respect to baseline value, or by both indices.

A distinct pattern of response emerged from these experiments.

1. Differences in ventilatory response among different subject groups were more pronounced immediately at the end of exposure, while at five hours postexposure the deflections tended to become less pronounced, returning to baseline levels.

2. Analysis for duration in textile work suggests that this variable is significant in modulating the spirometric responses, but the effect was opposite to that hypothesized. This finding, possibly the result of selection of the subjects (a survivors panel), is not compatible with the hypothesis accepting this factor as a determinant of enhanced response to dust proportional to duration of employment.

3. Individuals with long-standing respiratory complaints associated with exposure to dust at work (byssinosis subjects) appear considerably more responsive to the provocative test in terms of subjective complaints voiced during exposure, as well as ventilatory effects resulting from provocation, than those subjects equally exposed but free of long-standing reactive complaints to dust (ie, nonbyssinosis subjects).