Intervention studies of cotton steaming to reduce biological effects of cotton dust.

261-274. Previous exposure chamber studies had suggested that steaming cotton could reduce significantly the levels and the biological effects of cotton dust. Therefore an intervention study using a high capacity steamer was designed to test the effectiveness of this process in a single cotton mill. The mill population was surveyed and dust sampling was completed prior to intervention with steamed cotton. A panel of 62 byssinotics and heavily exposed workers was selected to serve as a test panel while steamed cotton was introduced to the mill. Following the introduction of adequately steamed cotton the mean Monday decrement in forced expired volume in one second among panel members was significantly reduced to half that observed during control trials. Dust levels were also significantly reduced in the initial opening and picking processes but increased significantly in later processes. Re-evaluation of the mill population by work area suggested some improvement in expiratory flow per milligram of dust exposure but a progression in symptoms of byssinosis and bronchitis in later mill processes. It is suggested that steaming may have resulted in removal of some bronchoconstricting property of cotton dust, but that binding of fine dust to the fibre may also occur, resulting in delayed release of fine dust particles. The implications of these observations on environmental control are discussed.