In vitro and in vivo tests for determination of the pathogenicity of quartz, diatomaceous earth, mordenite and clinoptilolite

The effects of samples of crystalline quartz, diatomaceous earth, mordenite and clinoptilolite were investigated in vitro (as concerns erythrocyte haemolysis and lactate dehydrogenase (LDH) release from peritoneal macrophages) and in vivo (on LDH, protein and phospholipids in rat bronchoalveolar lavage (BAL), and phospholipids in rat lung tissue). The respirable mineral samples were instilled intratracheally. Determinations in the BAL were carried out after 15, 60 and 180 days, and in the lung tissue after 90, 180 and 360 days. Quartz DQ and quartz FQ induced acute, subacute and chronic inflammation and progressive fibrosis. However, due to the Al2O3 contamination on the surface of the particles quartz FQ caused a delayed response in vivo. Diatomaceous earth produced acute/subacute inflammation that gradually became more moderate after 60 days. Clinoptilolite was inert, whereas the other zeolite sample, mordenite, was cytotoxic in vivo. The reason for this was presumably the needle and rod-shaped particles in the mordenite samples. The investigation revealed that different in vitro and in vivo methods canprovide valuable data concerning the pulmonary toxicity of minerals.