Occupational exposure and respiratory morbidity among asbestos workers in Taiwan

To determine the prevalence of asbestos-related lung disease and the impairment of lung function among asbestos workers, we conducted a cross-sectional health survey of 459 workers in 33 asbestos-related factories in Taiwan. Each worker was asked about his medical and occupational history and was given a medical examination, chest roentgenogram and pulmonary function test. Manufacturing processes included production of asbestos cements, textiles, friction materials and insulation products. Exposure assessments were based on asbestos sampling and counting using a phase contrast microscope. The average age of the participants in the study was 41.6 years. They had an average of 8.1 years of dust exposure, with a range of one to 42 years. The majority had a cumulative asbestos exposure of less than 20 fiber years/mL. No case of asbestos-related lung disease was found during our investigation. No roentgenogram showed unequivocal changes of asbestosis. However, a multiple linear regression analysis of the pulmonary function test showed that both FVC and FEV1 decreased significantly with an increasing cumulative dose of exposure after controlling for age, height and smoking effects during analysis. FEV1/FVC and FEF25-75% were not affected by exposure dose. The absence of asbestosis and other asbestos-related lung diseases may be due to an inadequate induction time of asbestos exposure and a possible healthy selection of workers. We conclude that among workers in Taiwan, there is a significant effect on the respiratory system, especially pulmonary function, due to asbestos exposure.