mordenite and Pulmonary-Fibrosis

Respirable mineral fibers, such as asbestos, are known to cause pleural mesothelioma, pulmonary fibrosis, and bronchial carcinoma, often years after exposure. Erionite and mordenite, two mineral aluminosilicates (zeolites) with different toxicities, can be used as models to help understand asbestos toxicity. Erionite is carcinogenic, while mordenite is relatively benign. No iron is typically present in erionite or mordenite, but because of their ion-exchange properties they can acquire iron after inhalation. The iron is typically in the Fe(III) form and will need to be reduced prior to any Fenton activity. Lung lining fluid contains antioxidants, such as glutathione (GSH) and ascorbic acid (AA), which can reduce Fe(III) to Fe(II). In this study, we have compared the Fenton reactivity of Fe(III)-exchanged erionite and mordenite after treatment with antioxidants. The Fenton assay involved the reaction of hydroxyl radicals with dimethyl sulfoxide. Fenton reactivity was most marked with AA followed by GSH, and hydrogen peroxide also exhibited minor reactivity. Erionite generated an order of magnitude greater hydroxyl radicals than mordenite, normalized to the surface iron content, providing support for the hypothesis that the iron coordination at the mineral surface plays a significant role in bioactivity.

Topics: Aluminum Silicates; Asbestos; Hydrogen Peroxide; Hydroxyl Radical; Iron; Lung Neoplasms; Mesothelioma; Oxidation-Reduction; Pulmonary Fibrosis; Zeolites

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.

Topics: Aluminum Silicates; Animals; Bronchoalveolar Lavage; Diatomaceous Earth; Erythrocytes; Hemolysis; Inflammation; Inhalation Exposure; L-Lactate Dehydrogenase; Lung; Macrophages; Male; Mining; Occupational Exposure; Phospholipids; Pulmonary Fibrosis; Quartz; Rats; Rats, Sprague-Dawley; Zeolites

An evaluation of the biological activity of Bulgarian zeolite rocks was made by the methods in vivo and in vitro. The results pointed out to specific biological effect--cytotoxic and fibrogenic--most strongly expressed for clinoptilolite followed by mordenite and erionite. The clinoptilolite is characterized by strong cytotoxic effect in comparison with dust of calibrated quartz DQ-12 which confirms the lack of correlation between cytotoxicity and fibrogenicity for some types of dust. On the basis of the results a temporary hygienic norm for clinoptilolite dust--2 mg/m3 is proposed.

Topics: Aluminum Silicates; Animals; Bulgaria; Dust; Hemolysis; In Vitro Techniques; Lung; Maximum Allowable Concentration; Pulmonary Fibrosis; Quartz; Rats; Time Factors; United States; Zeolites