Biological responses of workplace particles and their association with adverse health effects on miners

Epidemiological research has demonstrated the relationship between exposure to quartz dust and an elevated risk of pneumoconiosis and possible elevated risk of cancer. The current study was designed to evaluate the biological responses of workplace particles containing crystalline silica using an in vitro cell test. Respirable particle samples were sampled from four tin mines, where the standardized mortality ratio (SMR) for pneumoconiosis was 51.6 and SMR for lung cancer was 2.2 in dust-exposed miners. Alveolar macrophages (AM) are considered as the target cells for primary dust effects. The samples were then measured at 15, 30, 60 and 120 microg particle per 10(6) AM for cytoxicity with the release of glucuronidase, lactate dehydrogenase, for reactive oxygen damage with H(2)O(2) release, and for ability to induce fibrosis using the secretion of tumor necrosis factor-alpha (TNF-alpha). Pure quartz (DQ12) and corundum were used as controls. The results showed the samples from tin mines caused a higher cytoxicity when compared to corundum, yet lower when compared to quartz. However, reactive oxygen species release (148-177 nmol/3 x 10(5) AM in high concentration of 120 microg/10(6) AM) induced by the samples were significantly higher than that induced by quartz (57 nmol/3 x 10(5) AM) and corundum (62 nmol/3 x 10(5) AM). Furthermore, particle samples induced higher TNF-alpha secretion than corundum, the samples from Limu tin mine induced much higher TNF-alpha levels than that induced by DQ12 quartz. The results from the in vitro tests help elucidate the degree of hazard of dust particles in tin mines. The in vitro reaction patterns of AM also constitute a powerful tool to monitor biological and pathogenic responses of humans following dust particle exposure.