Respiratory Effects Among Cotton Workers in Relation to Dust and Endotoxin Exposure.

Cotton dusts contain agents, namely endotoxins, which can cause chronic inflammatory responses in the airways and the lung. We have hypothesized that the adverse effects of cotton dusts result from airborne endotoxin levels. The population studied comprised two groups: those who worked in the carding departments (opening, blowing, carding, drawing and roving) (n = 231) and those who worked in the weaving departments (n = 186). Cotton dust levels were monitored gravimetrically using Millipore polyvinylchloride filters and vertical elutriators with a 15 µm mass median aerodynamic diameter cut-off size. The amount of airbone endotoxin was determined using the Limulus amoebocyte lysate technique. Questionnaire administration and pulmonary function testing were carried out on each worker before entering the workshop after a 36 h rest period. Function tests were repeated at the end of the shift. In the carding department, workers were measured for airway reactivity. A test of bronchial reactivity was performed with graded doses of inhaled methacoline according the method described by Cockcroft et al. Time-weighted averages of cotton dust levels were highest in the carding departments (0.19-1.3 mg/m³) than in the weaving departments (0.11-0.58 mg/m³). The endotoxin levels in the carding departments varied between 2.5 and 58 ng/m³; endotoxin was not found in the weaving departments. The workers in the carding areas presented a higher frequency of respiratory symptoms (28.3%) than those in the weaving areas (12.7%). A relationship was found between decreases in FEV₁ and airborne endotoxin levels, but not for dusts. The average reaction to methacoline was related to the amount of airborne endotoxin. The results support the hypothesis of a dose-response relationship between endotoxin levels in cotton dust and chronic lung impairment in cotton workers and the presence of increased bronchial reactivity in workers in the cotton industry. [ABSTRACT FROM AUTHOR]