Extended Investigation of Exposure to Respirable Synthetic Amorphous Silica Dust and Its Potential Impact on Non-malignant Respiratory Morbidity

OBJECTIVES: The present analysis aims to study the health impact of an occupational exposure to respirable synthetic amorphous silica (SAS) dusts, based on the available data from the German study. METHODS: The effect of cumulative exposure to respirable SAS dust on respiratory morbidity were investigated in 462 exposed male workers. Multiple exposure assessments was performed anchored by a most recent measurement series. Internal regression models in addition to Monte Carlo-Multi Model were fitted. RESULTS: An averaged cumulative respirable SAS dust concentration of 6.44 mg/m(3)-years was estimated. Internal regression models suggested a reduction of 8.11 ml (95% confidence interval: 0.49–15.73) in forced vital capacity (FVC) per 1 mg/m(3)-year increase of exposure. But no effect on forced expiratory volume in 1 s (FEV(1)) and the ratio of the parameters FEV(1)/FVC was observed in association with exposure to a respirable fraction of SAS. No adverse effects on the occurrence of respiratory diseases were indicated. CONCLUSION: This study provides no clear evidence of adverse health effects from occupational exposure to respirable SAS. SPONSOR: Evonik Operations GmbH/Smart Materials, Cabot Corporation, Wacker Chemie AG.