Dose response effect of cement dust on respiratory muscles competence in cement mill workers.

Electromyography (EMG) of respiratory muscles is a reliable method of assessing the ventilatory muscle function, but still its use has not been fully utilized to determine the occupational and environmental hazards on respiratory muscles. Therefore, EMG of intercostal muscles was performed to determine the dose response effect of cement dust on respiratory muscles competence. Matched cross-sectional study of EMG in 50 non-smoking cement mill workers with an age range of 20 - 60 years, who worked without the benefit of cement dust control ventilation or respiratory protective devices. EMG was performed by using surface electrodes and chart recorder. Significant reduction was observed in number of peaks (p < 0.0005), maximum peak amplitude (p < 0.0005), peak-to-peak amplitude (p < 0.0005) and duration of response (p < 0.0005) in cement mill workers compared to their matched control. Cement dust impairs the intercostal muscle competence and stratification of results shows a dose-effect of years of exposure in cement mill.

Lung function and surface electromyography of intercostal muscles in cement mill workers.

Impairment of pulmonary function in cement mill workers has been previously reported without considering a variety of parameters that can help evaluate more thoroughly the effect of cement dust on the respiratory system. In addition, an integrated approach has not been considered to assert the involvement of respiratory muscles. Therefore, in the present study spirometry and surface electromyography (SEMG) of intercostal muscles were used for indicating pulmonary impairment. In this study, a group of 50, apparently healthy volunteers, male cement mill workers aged 20-60 years with exposure of 13 years on average, were randomly selected. They were matched with another group of 50 control healthy male subjects in terms of age, height, weight and socioeconomic status. Both groups met the standard exclusion criteria. Spirometry was performed on an electronic spirometer, while SEMG of intercostal muscles was performed by using a chart recorder. The results demonstrated statistically significant reduction in lung function parameters i.e., force vital capacity (FVC) (p < 0.0005); force expiratory volume in first second (FEV1) (p < 0.0005); peak expiratory flow (PEF) (p < 0.005); and maximum voluntary ventilation (MVV) (p < 0.0005) in cement mill workers, when compared with controls. However, the FEV1/FVC ratio was significantly higher (p < 0.025) in cement mill workers. Similarly, the parameters obtained from SEMG of intercostal muscles, i.e. number of peaks (NOP) (p < 0.0005); maximum peak amplitude (MPA) (p < 0.0005); peak to peak amplitude (PPA) (p < 0.0005); duration of response (DOR) (p < 0.0005) and maximum peak duration (MPD) (p < 0.0005), were significantly lower in cement mill workers than in controls. It is concluded that exposure to cement dust not only impairs lung function but also affects costal muscle performance, thus possibly indicating the decreased lung and thoracic compliance.

Hematological changes in cement mill workers.

OBJECTIVES: Considering the hazards of exposure to cement dust, this study incorporated basic hematological parameters, erythrocyte sedimentation rate and the total leukocyte count. The idea was to identify a simple, readily available and cost effective screening test that could help in identifying the presence of disease, its severity, or both in cement mill workers potentially related to their work place. METHODS: This study was carried out in the Department of Physiology, Faculty of Health and Medical Sciences, Hamdard University, Karachi and the University of Karachi, Pakistan, during the time frame 1999-2000. In this study a group of 50, apparently healthy volunteers male cement mill workers were randomly selected with ages ranging from 20-60 years. They were matched with another group of 50, control healthy male subjects in terms of age, height, weight and socioeconomic status. Both groups met with exclusion criteria as per standard. The total leukocyte count was performed on an auto analyzer, (Symex-K-1000 CP-Analyzer, Japan) and the erythrocyte sedimentation rate was measured by Westergren tube method. Results were compared in a mean, and on the basis of, period of exposure in a cement mill. RESULTS: In the present study, the mean values of erythrocyte sedimentation rate (p<0.05) and total leukocyte count (p<0.02) significantly increased, but the parameters do not revealing statistically significant differences between 2 groups on the basis of duration of exposure in a cement mill. CONCLUSION: This study has shown that exposure to cement dust causes increased mean values of total leukocyte count and erythrocyte sedimentation rate. However, this change is not related to the duration of exposure in a cement mill.