A study of the prevalence of respiratory morbidity among agate workers

Summary

A random sample of 342 workers engaged in chipping and grinding of agate stones were surveyed in a cross-sectional study to assess the prevalence of respiratory morbidity in the agate industry. The findings were compared with those obtained in controls. The study showed a significantly higher prevalence of lung diseases among agate workers than among controls (63.4% vs 35.5%, P < 0.001). The respiratory morbidity in agate workers and controls was maximal in the group aged 31+ years (83.3% and 42.2%, respectively). The prevalence of pneumoconiosis in agate workers (18.4%) was highly significant as compared with controls, in whom not a single case was found (P < 0.001). However, there was no significant difference between the prevalence of pneumoconiosis in men and women of the exposed group (17.9% vs 19.6%). Among the cases of pulmonary diseases in agate workers, pneumoconiosis formed the largest group (18.4%), whereas among controls it was tuberculosis (12.1%). The prevalence of pulmonary tuberculosis was very high in both agate workers and controls (15.5% and 12.1%, respectively), probably because of poor socio-economic and unhygienic living conditions. The prevalence of chronic bronchitis was found to be higher among the control population as compared with the exposed group (6.7% vs 2.6%). It therefore appeared that agate dust had no role in precipitating chronic bronchitis. However, bronchial asthma appeared to have been aggravated due to agate dust, as the risk among agate workers was 7-fold that found among the controls. The prevalence of pneumoconiosis showed a dose-response relationship in both male and female agate workers. Pulmonary tuberculosis and bronchial asthma did not show any significant trend in relation to the duration of exposure. Other lung diseases were also independent of exposure. As far as occupations are concerned, grinders were found to suffer more from pneumoconiosis (21.9%) than did chippers (7.3%, P < 0.05); this was because the respirable dust concentration at the workplace of grinders was 6-fold that at the workplace of chippers. Acute bronchitis was also more prevalent in grinders (P < 0.05). However, tuberculosis and asthma did not vary significantly between the two occupational groups.