Pulmonary Function Response to Dust from Standard and Closed-Boll-Harvested Cotton 1

Abstract

Twenty-six volunteers with normal pulmonary function were exposed to cotton dust in a model card room. Exposures were carried out on alternate days, and spirometry was performed before and after six hours of exposure. Dust levels were measured with vertical elutriators and adjusted by varying carding rate and exhaust veritilation. "Standard" cotton was harvested and prepared for carding in the usual manner. "Closed-boll" (CB) cotton was harvested before the bolls had opened; the bolls were washed in a 0.5% sodium hypochlorite solution and then allowed to open under controlled conditions. Bract was manually removed prior to opening on one-half of this cotton. CB cotton was obtained from Stoneville, Mississippi and Lubbock, Texas. Four exposures to standard cotton from Stoneville were carried out, but only one exposure was carried out for each type of CB cotton due to the small quantities available. Results were analyzed for statistical significance. Forced expiratory volume in one second (FEV,) rose slightly over the day with no exposure and fell slightly after rayon exposure. Both changes were significantly different from the average fall of 5% after standard cotton exposure. Mississippi CB cotton, with or without bract, and Texas CB cotton without bract caused significantly smaller declines in FEV 1 than standard cotton. These declines were not significantly different from each other or from that associated with rayon exposure. The Texas CB cotton with bract caused a 10% decline in FEV,, which was significantly greater than that for standard cotton. In normal volunteers, airway response is less to dust from closed-boll cotton without bract than to standard cotton dust. Differences in response to dust from CB cotton with bract from Mississippi and Texas are to be studied further.