A longitudinal study of pulmonary function in cotton gin workers in the San Joaquin Valley

In a previous study we found no significant effects of acute exposure to the cotton gin environment on FEV1 in San Joaquin Valley gin workers compared with concurrent control subjects, nor was there an excess of obstructive lung disease among the same gin workers. The present study looked at the mean annual decline in FEV1, FEV1/FVC, and FEF25-75% in San Joaquin Valley cotton gin workers vs concurrent control subjects over four years. The FEV1 of gin workers completing all four years of the study declined 27.3 ml vs 35.5 ml in control subjects (p = 0.37); FEV1/FVC declined 0.21 percent in gin workers and 0.23 percent in control subjects (p = 0.86); FEF25-75% declined 0.058 L/s in gin workers and 0.066 L/s in control subjects (p = 0.68). Also, the mean annual rate of change of FEV1 was less among the gin workers who did not complete all four years than the gin workers completing all four years. The presence of "byssinosis" symptoms did not significantly influence the results. This prospective, longitudinal study failed to find any detrimental effect of the cotton gin environment on the rate of decline of FEV1, FEV1/FVC, and FEF25-75%. This result was independent of "byssinosis" symptoms and the effect of "dropouts."