Respiratory effects of exposure to low levels of concrete dust containing crystalline silica

Background Dusts containing crystalline silica are generated in mining, construction, glass, granite and concrete production industries. The association between exposure to low levels of concrete dust containing crystalline silica and reduction in lung function, was evaluated in a cross-sectional study. Methods The study was carried out among 144 concrete workers, from two factories, with exposure assessment of respirable dust and silica by personal samplers. Results of respiratory questionnaires and standardized measurements of lung function were compared with the results in a control population. Multiple linear regression analysis was used in selecting factors that predict (age and standing height standardized residual) lung function. Results The average concentration of respirable dust in both factories was 0.8 mg/m(3) and 0.06 mg/m(3) for respirable silica. The average silica content of the dust was 9%. The average cumulative dust exposure was 7.0 mg/m(3) year and cumulative silica exposure was 0.6 mg/m(3) year Significant associations between exposure to concrete dust and a small lung function (FEV1/FVC ratio, MMEF) loss were found, independent of smoking habits and of a history of allergy. Conclusions Our results indicate that, concrete workers with chronic obstructive pulmonary symptoms andlor work-related lower respiratory symptoms are at risk of having a reduction in lung function (FEV1/FVC ratio) outside the 5th percentile of the external reference population, and therefore, of mild chronic obstructive pulmonary disease, at respirable concrete dust levels below 1 mg/m(3) with a respirable crystalline silica content of 10% (TWA, 8 hr). (C) 2001 Wiley-Liss, Inc.