Respiratory changes in two groups of flax workers with different exposure pattern.

, , 579-583. A high mean total concentration of flax particles (16·9 mg/m), of which about 20% were of respirable size, caused a high prevalence of bysinosis (69·9%) in 55 non-smoking female workers exposed to biologically retted flax over an average period of 11 years. A significant mean FEV decrease over the first work shift after the weekend break was recorded in both byssinotics and non-byssinotics but was more pronounced in the former. The mean acute FEV reductions over a work shift were smaller on the third than on the first day in the week. Significant decreases in FEV and in maximum expiratory flow rate at 50% of vital capacity over the Monday work shift were recorded in a group of 17 seasonal male workers who had been exposed to flax for only two to three months each year for no more than three years. A high prevalence of chronic cough, chronic sputum production, and chronic bronchitis was found in the female flax workers, especially among the byssinotics.