Effect of cotton, hemp, and flax dust extracts on lung permeability in the guinea pig.

Byssinosis is an occupational lung disease in textile mill workers exposed to the respirable dusts of cotton, hemp, and flax. This study investigated the influence of aqueous extracts from these dusts on overall lung permeability in the guinea pig as an index of respiratory epithelial damage. Lung permeability was assessed by absorption into blood from the lung of inhaled technetium-99m diethylenetriamine penta-acetate (Tc-DTPA) using gamma-scintigraphy. The half-life for Tc-DTPA absorption (t1/2) was significantly reduced following a 4-week inhalation treatment with cotton, hemp, or flax dust extracts when compared to saline control. There was at least a partial return to normal permeability 7 days after stopping treatment. A single inhalation of extract did not affect the t1/2, but increased the number of neutrophils in bronchoalveolar lavage fluid 24 h postexposure. Neutrophil migration into the airspaces therefore appeared to precede the increased lung permeability. Long-term exposure was not associated with respiratory epithelial shedding, suggesting that the increased permeability reflects a loss of epithelial tight junction integrity arising from repeated exposure to as yet undefined agents in these dusts.