One-week variation of cotton dust and endotoxin levels in a cotton mill. Relation with the daily variation of the expiratory flow rates.

Abstract

The prevalence of respiratory occupational diseases in the textile industry depends on environmental factors such cotton dust (CTD) levels and gram negative bacteria endotoxin (EDX) contamination.To assess the environmental conditions (CTD and EDX) during one week in a cotton mill with respect to FEV1 variation throughout the work shift.47 cotton mill workers (24F, 23M); average age: 42 +/- 11 years; average exposure to cotton dust: 22.5 +/- 9.4 years; Asthma: 15 (32%), Byssinosis: 11 (23%) and Asymptomatics: 21 (45%); a past history of respiratory symptoms: 13.1 +/- 11.7 years. Clinical evaluation, skin prick tests, a metacholine challenge, lung function tests and a work-place evaluation were performed. FEV1 Shift-variation (Delta-Shift) = end-shift FEV1 - start-shift FEV1, was calculated during one week. CTD and EDX levels were measured daily for each work place throughout this week and everyday during different operation tasks (work, cleaning, maintenance). The average values of CTD and EDX were calculated according to the time spent on each of these tasks for every worker who was exposed.Great variability of the environment conditions was observed throughout the week with the highest levels of CTD and EDX on Friday, even in comparison with Monday (CTD = 1.01 +/- 0.31 mg/m3 vs 0.68 +/- 0.65 mg/m3; p < 0.0005 e EDX = 33.1 +/- 8.9 ng/m3 vs 20.8 +/- 9.4 ng/m3; p < 0.0001). The shift variation was -129 +/- 97 ml for all the workers. The workers with asthma had the greatest reduction in expiratory flow rates, highest BHR and Delta-Shift but there were no differences in the levels of CTD and EDX among the three groups. Delta-Shift showed an association with the levels of EDX, specially in individuals with BHR but not with CTD levels.The environmental conditions that textile workers are exposed to, varies throughout the week and are associated with variations in flow rates and so lung function tests should be performed in a serial manner for the evaluation of respiratory occupational disease. The highest levels of EDX were recorded on Friday and this confirms the low reliability of the diagnostic criteria of byssinosis and points to the necessity of more objective measures.