OBJECTIVES To examine the causes of death among 1130 former workers of a plant in Tyler, Texas dedicated to the manufacture of asbestos pipe insulation materials. This cohort is important and unusual because it used amosite as the only asbestiform mineral in the production process. High level exposure of such a specific type was documented through industrial hygiene surveys in the plant. METH...

Primary malignant mesothelial tumours were recognized by pathologists before asbestiform minerals (chrysotile, crocidolite and amosite) were mined commercially. The discovery, 40 yrs ago, of a causal link with crocidolite and the wide-ranging epidemiological studies which followed are the subject of this review. Early case-control and descriptive surveys, supplemented by cohort studies in insul...

The mode of action of inorganic fibers as carcinogens is unknown. There is conflicting evidence whether they act by inducing lesions in DNA, such as initiating carcinogens, or alternatively act as promoters of carcinogenesis. Recent evidence has suggested that promoters inhibit the process of cell-to-cell chemical communication known as metabolic cooperation. Chinese hamster V79-4 cells in cult...

The mechanism of toxicity of selected asbestos substitute mineral fibres was examined and compared to that of asbestos. Alveolar macrophages and type II cells were isolated from Fischer 344 rats and after 20 h cultivation various concentration of fibres alone (amosite, wollastonite, rockwool or glass fibres) or in combination with cigarette smoke were added to cells and the cultivation continue...

OBJECTIVE To investigate the ability of short and long fibre samples of amosite asbestos to stimulate superoxide production in isolated rat alveolar macrophages, and to determine how opsonisation with rat immunoglobulin might modify this response. METHODS Macrophages were isolated from rat lung by bronchoalveolar lavage and challenged with both opsonised and non-opsonised long and short fibre...

In vivo tests available to determine the toxicity of mineral fibers are too expensive and time-consuming to be regularly employed in the evaluation of the potential health hazard posed by natural and man-made fibers. In vitro procedures, while economical, convenient and capable of ranking "relative toxicity," are uncertain predictors of specific lesions. Thus, it is of interest to compare the r...

Although asbestos stimulates oxygen radical generation in alveolar macrophages, the exact mechanism is still not clear. The purpose of this study was to compare the ability of three asbestos fibers (amosite, chrysotile, and crocidolite) to generate oxygen radicals in macrophages and examine the mechanism of this action. All asbestos fibers were able to induce chemiluminescence but chrysotile in...

Fluorescence microscopy-based affinity assay could enable highly sensitive and selective detection of airborne asbestos, an inorganic environmental pollutant that can cause mesothelioma and lung cancer. We have selected an Escherichia coli histone-like nucleoid structuring protein, H-NS, as a promising candidate for an amphibole asbestos bioprobe. H-NS has high affinity to amphibole asbestos, b...

The lungs of 50 symptom free workers exposed to amosite and with normal pulmonary function tests were examined by high resolution computed tomography (HRCT). Twenty five had normal standard chest radiographs whereas the other 25 had radiographs interpreted as near normal (International Labour Office profusion score < 0/1 or suspected pleural plaques). In 13 of the workers the results of HRCT we...

Previous animal experiments with asbestos dusts have been almost entirely confined to chrysotile asbestos. It was, therefore, decided to investigate the effects of mill dusts from the three types of asbestos that are produced commercially in South Africa, namely chrysotile, amosite, and crocidolite. Chrysotile and amosite samples were relatively pure while in contrast the crocidolite dust was f...