Amounts Of Chrysotile Research Articles

Association of lung tissue content of different mineral fibre types with occurrence of malignant mesothelioma

ObjectivesWhile dose-response relationships between airborne crocidolite and malignant mesothelioma (MM) have been well established, corresponding relationships for lung tissue burden are less clear. The objective was to examine the association...

Characterization of Serpentinites for Potential Use as Dimension Stone

Abstract Serpentinites are widely distributed in Egypt, particularly in central and southern parts of the Eastern Desert. There are several inter-related factors that affect the use of serpentinites as dimension stone. These factors involve mineralogical characteristics (including mineral compositions and microstructural parameters), physical properties, and mechanical properties. The main factor identified in this study is orientation of foliation planes in serpentinites. Samples that are selected parallel to foliation planes have higher mechanical properties than those perpendicular to it. Antigorite is the essential serpentinite mineral with minor amounts of chrysotile. Talc, carbonates (magnesite and dolomite), and tremolite are the main associated minerals. Quality and quantity of associated minerals such as talc and carbonates greatly influence the proper use of serpentinites as dimension stone. Studied serpentinites are characterized by relatively small grain size and foliated texture, low water absorption, low porosity, and high abrasion resistance. Physico-mechanical properties of studied serpentinites as well as mineralogical characteristics lead us to conclude that these serpentinites are suitable for specific applications as dimension stone.

Demolition of Gypsum Wallboard with Asbestos-Containing Mastic

This paper reports a series of laboratory and field tests that measured the asbestos (chrysotile) fibers released during demolition of gypsum wallboard (GWB) that contained small amounts of chrysotile in the joint mastic. The tests include contractors’ data from two actual demolitions, a controlled demolition of a wall segment, and bench top laboratory tests of gypsum wallboard samples. The results of all these tests indicated that many fibers are released during GWB demolition, but few if any of the fibers were chrysotile. The use of electron microscopy demonstrated that less than 2% of the fibers counted from laboratory and controlled demolitions using light microscopy procedures was asbestos. The actual field demolitions, which included asbestos containing material other than GWB, indicated that less than 4% of the fibers counted using light microscopy procedures was asbestos.

Fiber levels and disease in workers from a factory predominantly using amosite.

The Cape Boards Plant at Uxbridge produced insulation board containing amosite asbestos between 1947 and 1973 with only small amounts of chrysotile. After 1973 only amosite was used. In this study we examined lung samples from 48 workers who had been employed at the plant and who had come to autopsy. The study investigated the fiber levels against the lung pathology including amount of interstitial fibrosis and numbers of ferruginous bodies. The degree of interstitial fibrosis and number of asbestos bodies were graded and the tissues were analyzed by transmission electron microscopy and energy dispersive X-ray analysis and the fibers counted and typed. The 48 cases included 5 mesotheliomas and 14 lung cancers. The mineral analysis results were dominated by the amosite fiber levels. The amounts of chrysotile were relatively small. There were higher levels in lung cancer cases than mesotheliomas and higher levels in mesothelioma cases than those who had died from nonasbestos related diseases. Analysis of the lung tissues showed a consistent pattern of high amosite levels, which confirms the impression that amosite was the predominant form of asbestos used and also indicates that the factory had been a very dusty one.

The use of liposomes in the investigation of mechanisms of asbestos damage.

Asbestos-induced cell damage is initiated by a reaction at the plasma membrane. The effect of chrysotile (which is more hemolytic and releases more silicic acid than other types of asbestos) on permeability changes of liposomes has been investigated. The destabilizing effect rises when the amount of chrysotile is increased. Silicon dioxide is one major constituent which could be a hemolytic agent, and a cause of damage. It also caused an increase of permeability of liposomes.

Mössbauer spectra study on Xiu-Yan Jade

Having beautiful colours and fine features, Xiu-Yan Jade is famous in the world. Mineralogically, Xiu-Yan Jade is serpentine jade. XRD, IR and TEM study indicate that the jade consists mainly of antigorite (m{Mg3(1−1/m)[Si2O5](OH)1+3(1−2/m)}) with a minor amount of chrysotile. Two favourite samples (PXA, PX1−t) are chosen for research on57Fe Mossbauer spectra. Two sets of quadrupole doublets are obtained from the spectra, The parameters of two samples, 1. 124 mm/s and 1. 119 mm/s of I. S. and 2. 732mm/s and 2. 716mm/s of Q. S. for Fe2+ in the octahedral and 0. 364mm/s and 0. 351mm/s of I. S. 0. 632 and 0. 546mm/s of Q. S. for Fe3+ in the octahedral, are only antigorite. Studies indicate that: (1) iron—ion in antigorite enters the lattice as impurity: (2)Fe2+ and Fe3+ substitute for Mg in the coordination octahedron: and (3) the colour of jade is related to content of Fe, and Fe3+/Fe2+≤1 is favourite for colour—forming.

Asbestos fiber content of the lungs in patients with and without asbestos airways disease.

I analyzed the total pulmonary asbestos burden in the lungs of 9 chrysotile miners who had asbestos airways disease (so-called "early asbestosis") but no evidence of classic asbestosis (interstitial fibrosis) on pathologic examination. The results were compared with values found for 9 miners matched for age, sex, smoking, and work length who had no histologic evidence of asbestosis or asbestos airways disease. The mean value for chrysotile fibers in the airway disease group was 47 X 10(6)/g dried lung, compared with 23 X 10(6) in the group without lesions (p less than 0.04). For contaminant amphiboles, probably derived from the chrysotile ore (tremolite, actinolite, anthophyllite), the corresponding values were 106 X 10(6) versus 58 X 10(6) (p less than 0.06), and for total asbestos fibers, 153 X 10(6) versus 81 X 10(6) (p less than 0.06). There was a strong correlation between amount of chrysotile and amphibole for each case, suggesting that the amphibole was probably a good measure of the original (but no longer present) chrysotile burden. No differences were seen between the 2 groups with regard to fiber size distribution, aspect ratios, or fiber widths. I conclude that the overall differences in fiber concentration between the 2 groups, although significant, are sufficiently small enough to suggest that other factors may be involved in the genesis of small airway lesions.

A PATHOLOGICAL AND MINERALOGICAL STUDY OF ASBESTOS-RELATED DEATHS IN THE UNITED KINGDOM IN 1977

Lung tissue samples from Pneumoconiosis Panel cases comprising workers whose deaths were considered to be asbestos-related and from controls exposed to different levels of urban pollution were examined histologically and analysed for mineral fibre content. The Panel cases had on average about 100 times more amphibole fibres in their lungs than the controls, but the amounts of chrysotile were similar. Considering the much greater industrial usage of chrysotile, this points to lower deposition and/or more rapid elimination of chrysotile from the lungs. There was a clear association between asbestosis grade and amphibole, but not chrysotile, content in the Panel cases; the amount of amphibole was similar for those with mesothelioma, those with lung cancer and those with neither of these tumours.

Penetration of >5-µm chrysotile fibers through DuPont Tyvek 1422A and Kimberly-Clark CPF fabrics

Aerosols of 4.1-µm mass median aerodynamic diameter chrysotile fibers were generated and passed through stitched (seamed) and unstitched (unseamed) DuPont Tyvek 1422A and Kimberly-Clark composite polypropylene fabric (CPF) spunbonded fabrics. The two unstitched fabrics and the two stitched fabrics were penetrated by amounts of chrysotile, which did not allow a statistically significant difference in penetration to be observed. Both Tyvek and the CPF allowed approximately a 1% penetration through the unstitched material and approximately a 30% penetration through the stitched material. These values refer to the suit materials perse and not to the entire garment. As such, they should not be considered as representative of the entire suit as worn by personnel.