vermiculite and Lung-Diseases

Topics: Aluminum Compounds; Aluminum Silicates; Animals; Calcium Compounds; Glass; Humans; Iron; Kaolin; Lung Diseases; Magnesium; Magnesium Compounds; Mesothelioma; Minerals; Mining; Occupational Diseases; Pleural Neoplasms; Pneumoconiosis; Silicates; Silicic Acid; Talc; Zeolites

Epidemiological data suggest that occupational exposure to the amphibole-containing vermiculite in Libby, MT, was associated with increased risk for developing autoimmune diseases and had an odds ratio of 3.23 for developing rheumatoid arthritis (RA). The collagen-induced arthritis (CIA) and the peptidoglycan-polysaccharide (PG-PS) models of RA were employed to determine whether exposure to Libby amphibole (LA) induced a more rapid onset, increased expression, or prolonged course of RA. Female Lewis rats were intratracheally instilled with total doses of 0.15, 0.5, 1.5, or 5 mg LA or 0.5 or 1.5 mg amosite asbestos, and arthritis was induced with either the PG-PS or CIA model. Neither LA nor amosite exposure affected the disease course in the CIA model, or the production of rheumatoid factor (RF) or anti-cyclic citrullinated peptide (CCP) antibodies. LA exposure reduced swelling in the PG-PS model and decreased anti-PG-PS and total immunoglobulin M (IgM) antibody titers. Both amosite and LA exposure increased the number of rats with circulating anti-nuclear antibodies (ANA), the majority of which presented a speckled staining pattern. However, this ANA enhancement was not dose responsive. These results failed to show a positive correlation between LA exposure and RA disease in two animal models, although upregulated ANA suggest an altered immunological profile consistent with other systemic autoimmune diseases.

Topics: Aluminum Silicates; Animals; Antibodies; Arthritis, Experimental; Arthritis, Rheumatoid; Asbestos, Amphibole; Biomarkers; Dose-Response Relationship, Drug; Female; Immunoglobulin G; Injections, Spinal; Joints; Lung Diseases; Rats; Rats, Inbred Lew; Time Factors

Chest radiographs taken by a standard technique were obtained from 173 current employees (164 men, 9 women) of a vermiculite mine in Montana, from 80 of 110 past employees resident within 200 miles, and from 47 men from the same area without known exposure to dust. In 43 of the 80 and 24 of the 47 an earlier chest x ray film was retrieved from the hospital archives. All 367 films were assessed blind and independently by three experienced readers using the ILO 1980 classification. Median radiographic assessment scores were analysed in relation to estimated cumulative exposure to the amphibole fibres that contaminate the vermiculite. Logistic regression analyses showed independent effects of age, smoking, and exposure on the prevalence of small opacities and of age and probably of exposure on pleural thickening. Overall, the data suggest that by retirement age the increase in prevalence of small opacities (greater than or equal to 1/0) lies between 5% and 10% per 100 f/ml years. This gradient may be somewhat steeper than for chrysotile miners and millers, but not much so.

Topics: Adult; Age Factors; Aged; Aluminum Silicates; Asbestos, Amphibole; Female; Humans; Lung; Lung Diseases; Male; Middle Aged; Mining; Occupational Diseases; Pleura; Pleural Diseases; Radiography; Silicic Acid; Silicon Dioxide