Student Research: Tanongsak Yingratansuk
A cross-sectional study of dust exposure and health outcomes was conducted in a stone carving company in Thailand. 147 respirable dust samples were collected and 97 subjects participated in the study during November 1998 to October 1999. Exposure indices were constructed and health outcomes of interest including respiratory symptoms, pulmonary functions, and chest radiographs were assessed. The results showed that the severity of employees' current exposures to quartz was 0.5 to 8.8 times the ACGIH-TLV, depending on job and site. Duration of exposure ranged from 4 months to 30 years. The prevalence of silicosis (profusion grade 1/0 and or greater) was 2%. Pulmonary tuberculosis was also detected in 4%. Linear regression analyses revealed that lung function was decreased among workers with longer work duration (p-value <0.05), regardless of age, sex, height and smoking status. No clear associations were seen between cumulative exposure metrics and indicators of silicosis. Elevated silicosis exposure levels indicate an on-going risk of silicosis in this industry. Employees' exposure increased because of the use of grinding tools with no ventilation and their proximity to other workers. However, because the number of workers with dust exposure histories was limited, exposure measurements were confined to current conditions.