Varieties Of Asbestos Research Articles

The incidence of malignant mesothelioma in Australia, 1947-1980.

Details of patients with malignant mesothelioma that was diagnosed in Australia before 1981 were obtained by searching all possible sources throughout Australia as far into the past as possible and up to and including 1980. The earliest patient with mesothelioma who was identified was diagnosed in Victoria in 1947. By 1980, 535 (81%) men and 123 (19%) women had been diagnosed with the disease; only 14 persons were aged less than 35 years at the time of diagnosis (the youngest person was 15 years of age). The incidence rate in subjects who were 35 years or older at diagnosis was less than 1.0 cases per million person-years until 1964-1968, and then it rose progressively to 15.5 cases per million person-years in 1979-1980. The highest rate (69.7 cases per million person-years) was observed in 65- to 74-year-old men in 1979-1980. The incidence rate in Western Australia was greater than were the rates in other states of Australia after the mid 1960s. Pleural mesotheliomas accounted for 88% of cases in which the site of the tumour was known; peritoneal mesotheliomas accounted for 10% of such cases and "other" sites for 2% of such cases. In 6% of cases the site was not specified. The exposure to asbestos was stated as "definite" in 59% of the cases with a recorded history of exposure: 8% of all the cases in the study had been exposed to crocidolite (blue asbestos) from Wittenoom Gorge in Western Australia. The age at diagnosis of patients with known exposure to asbestos was similar to that in those without known exposure. The increases in the incidence of malignant mesothelioma in Australia follow the published trends in the production and use of the amphibole varieties of asbestos in this country after a lag period of between 20 and 30 years.

Trace elemental analysis of asbestos with an x-ray fluorescence technique

We have used an X-ray fluorescence spectroscopic technique to quantify the trace elements present in Indian asbestos samples. Elements such as Cr, Mn, Fe, Ni, Cu, Zn and Ba were commonly found in all the asbestos varieties. The differences in the trace element content of Indian samples as compared to other global samples could be attributed to the different geochemical processes involved in the formation of ores at different places. The importance of trace metals has been briefly discussed in relation to their likely adverse biological effects.

Asbestos in lake and reservoir waters of Staten Island, New York: Source, concentration, mineralogy, and size distribution

There is strong evidence indicating that the six commonly recognized varieties of asbestos are cancer-producing agents Epidemiological and experimental data indicate that, although response to inhalation exposure is most marked, exposure by ingestion probably also entails a risk of excess tumor incidence. The toxicity of mineral fibers can be related to fiber dimensions, mineralogy, chemistry, and surface-active properties.

Laser microprobe mass analysis of o-phenylenediamine on asbestos fibres

The adsorption behaviour of o-phenylenediamine and its catalytically formed oxidation products such as 2,3,-diaminophenazine and higher-molecular-weight compounds on different varieties of asbestos is studied by using laser desorption mass spectrometry. The results prove that amosite adsorbs the product more easily than do crocidolite and anthophyllite, whereas U.I.C.C. chrysotile A does not give rise to detectable adsorption, and the adsorption observed for U.I.C.C. chrysotile B is only fair. The method shows potential for the investigation of the surface reactivity of pure and industrially transformed asbestos and other fibrous materials.

Laser microprobe mass analysis of N,N-dimethylaniline and catalytic oxidation products adsorbed on asbestos fiber surfaces

The adsorption behaviour of different asbestos varieties for N,N-dimethylaniline and its catalytically formed oxidation products e. g. Methyl Violet is studied using laser microprobe mass analysis (LAMMA) in laser desorption conditions. The results prove that amosite and chrysotile adsorb more easily than crocidolite, whereas anthophyllite does not give rise to a detectable adsorption. In the presence of hydrogen peroxide, the method developed shows potential for the investigation of the surface reactivity of pure and industrially transformed asbestos and other fibrous materials.

Identification of respirable asbestos fibres by quantitative x-ray microanalysis with a scanning transmission electron microscope (STEM)

Quantitative X-ray microanalysis of respirable asbestos fibres, based on the ratio method, enables the identification of different asbestos varieties in the submicrometre diameter range. A new identification scheme is proposed and applied for samples from an asbestos-cement factory and from a mining site. STEM analysis is compared with other methods of single particle analysis.

The metrology of asbestos

Asbestos is a widespread industrial product. Its unique properties lead to many uses. The risks to health resulting from the processing and handling of different varieties of asbestos are discussed; the different methods for evaluating the effects of pollution of air and water on biological tissues are reviewed; and their quality is discussed.

The identification of asbestos

SUMMARYTechniques are described for identifying and distinguishing between the six varieties of asbestos. When the fibres are large and numerous, as is the case for insulation materials, simple optical or X‐ray methods suffice. For environmental samples one must normally resort to electron microscopic techniques for a positive identification. When asbestiform minerals are to be distinguished from other fibrous silicates it is often necessary to use both electron diffraction and X‐ray spectrometry.

Biochemical Changes and Pulmonary Response of Guinea Pigs to Asbestos Dust

Abstract The biochemical and histopathological changes in lungs of guinea pigs were studied 120 days after intratracheal injection of three varieties of asbestos dusts, viz. chrysotile, amosite and anthophyllite. The salient histopathological features observed were the development of dust cell lesions in the lungs of animals exposed to the different varieties of asbestos. Maximum fibrosis and minimal asbestos body formation was observed in animals exposed to chrysotile and anthophyllite, respectively. With amosite and anthophyllite the development of diffuse interstitial fibrosis ensued, accompanied by well developed asbestos body formation in the amosite exposed animals. Biochemical studies revealed significant alterations in various phosphorylated compounds, an accumulation of orthophosphate and depletion of esters and nucleotides being very marked. RNA content increased significantly in the amosite treated group while the nucleic acid content remained unaltered in the chrysotile group.

Physical parameters of airborne asbestos fibres in various work environments-preliminary findings.

The results of a pilot investigation to describe the physical parameters, length, aspect ratio, mass and shape of airborne fibres in a variety of industries producing processing and handling chrysotile, amosite and crocidolite are described. Samples of airborne dust were collected on nucleopore membrane filters and examined by scanning electron microscopy. The diameters and lengths of airborne fibres collected during the dumping of raw amosite at an asbestos products plant were greater than those of fibres collected during the application of amosite insulation. Chrysotile fibres collected in the carding area of an asbestos textile plant also tended to have smaller diameters than fibres collected in the dryer and bagging areas of an asbestos mill. The measurements of fibre dimensions indicate that the degree of protection afforded a worker by optical counts using the membrane filter technique is likely to depend on variety of asbestos and stage of processing. Preliminary results are not in conflict with experimental data suggesting that asbestosis might be related to the mass of airborne dust and primary malignant mesothelial tumors to exposure to fibres in a specific range of fibre diameter and length.

In vitro studies on the cytotoxic action of different varieties of asbestos dust on macrophages.

Abstract: The cytotoxic action of a variety of asbestos dusts viz. chrysotile, amosite, anthophyllite, tremolite and actionlite was tested in vitro using alveolar and peritoneal macrophage cell cultures. The release of acid phosphatase and the uptake of the dye erythrosin B were taken as parameters of cytotoxicity. Among the several varieties of asbestos tested for this purpose, chysotile proved to be most cytotoxic for both the alveolar and peritoneal macrophages, although the former were more sensitive. Amosite was only slightly toxic for alveolar macrophages. Anthophyllite, tremolite and actinolite behaved as control inert dusts. Carboxymethylcellulose exhibited an anticytotoxic effect when chrysotile was pretreated with the polymer or when the dust cell interaction was allowed to take place in its presence.

Fibrogenic response in murine lungs to asbestos

Pulmonary fibrogenic response was investigated in mice following intratracheal inoculation of amosite, anthophylite and tremolite varieties of Indian asbestos and studies were made over a period of 150 days. At early periods all the varieties produced acute inflammatory reaction in the lungs. Thick reticulum fibers were encountered at later periods with amosite, while only thin reticulum fibers developed with anthophyllite or tremolite variety. The formation of asbestos bodies did not take place with any of the asbestos varieties even at 150 days. The deviation in the pulmonary fibrogenic response in mice has been attributed to species difference.

Modification of biological surface activity of particles.

The hemolytic activity of fibrous asbestos varieties and of fibrous or granular silica dust can be markedly reduced by adsorption of polymers. Polyanions exert a specific action on asbestos, particularly chrysotile, whereas silica is inactivated by nonionic polymers. A high degree of reduction of the lytic action by comparatively small amounts of the antagonistic polymers can be demonstrated after short exposure to concentrations of 0.1-0.4 mg/ml of appropriate polymers. Inactivation is based on stable adsorption. Repeated washings of inactivated mineral sediments or exposure to elevated temperatures (80-120 degrees C) produced no essential loss of the reduction of lytic potency. In one example, inactivation of chrysotile by sodium alginate, depolymerization by ascorbic acid was also ineffective.

Modification of Biological Surface Activity of Particles

The hemolytic activity of fibrous asbestos varieties and of fibrous or granular silica dust can be markedly reduced by adsorption of polymers. Polyanions exert a specific action on asbestos, particularly chrysotile, whereas silica is inactivated by nonionic polymers. A high degree of reduction of the lytic action by comparatively small amounts of the antagonistic polymers can be demonstrated after short exposure to concentrations of 0.1–0.4 mg/ml of appropriate polymers. Inactivation is based on stable adsorption. Repeated washings of inactivated mineral sediments or exposure to elevated temperatures (80–120°C) produced no essential loss of the reduction of lytic potency. In one example, inactivation of chrysotile by sodium alginate, depolymerization by ascorbic acid was also ineffective.

Chemical aspects of Indian varieties of asbestos dust

Actinolite, anthophyllite, amosite, chrysotile and tremolite varieties of asbestos from Indian mines were analysed for their chemical composition. Significant differences were found as compared with the composition of corresponding foreign varieties. The significance of this in relation to their possible toxic effects and the need for toxicological work with Indian varieties are discussed.

Pulmonary fibrogenic response of guinea pigs to amosite dust.

The fibrogenic response of amosite variety of asbestos was studied in lungs of guinea pigs over a period of 300 days. Histologically there was marked reticulin fibrosis but the maturation into collagen was slow. Biochemical estimation revealed significant increase of hydroxyproline and glycosamine contents. Total lung protein was also found to be higher in the amosite treated animals reaching maximum at 90 days. The significance of these findings have been discussed.

Asbestos bodies, their formation, composition and character

Asbestos bodies extracted from human lungs have been examined under the electron microscope to determine their morphology and diffraction characteristics. The asbestos bodies were extracted from the lungs of persons exposed to the four types of commercial asbestos fiber, namely cocidolite, amosite, anthophyllite and chrysotile. Asbestos bodies were rarely formed on fibers less than 10 μm in length and practically always on straight fibers. They were found to occur on all the four commercial varieties of asbestos but less frequently on chrysotile fibers. The characteristics of the individual fibers were found to play a large part in determining the range and frequency of body shapes observed. There appears to be no evidence to suggest stepwise formation of asbestos bodies. Asbestos bodies were found to have a major crystalline component which is structurally similar to extracts of ferritin produced from animal and human organs. The material forming the asbestos body is definitely biological in origin and corresponded closely to the material defined in the medical literature as hemosiderin.

Whisker-like Fibres from Chrysotile Asbestos

THE majority of the asbestos deposits at present being developed are of chrysotile, which emerges as fine, white fibres when the asbestos rock is separated or “opened” at the mine1. Amphibole asbestos usually has a harsher, more needle-like cleavage and in some applications where coarse straight fibres are desirable these latter forms are preferred. Chrysotile is more heat resistant than crocidolite (one of the amphiboles) which is its chief rival as a reinforcing agent and is, moreover, appreciably less dense than the other forms, 2.5 g/cc instead of 3.2 g/cc. This is a significant advantage in a reinforcing fibre, because the actual mechanical properties of the principal varieties of asbestos are all rather similar2. (Young's modulus approximately 16 × 103 kg mm−2; tensile strength 140–350 kg mm−2.)

Ovarian cancer and asbestos

There is a rising death rate from ovarian cancer in advanced western countries. By contrast, ovarian cancer is uncommon in less developed areas. Mesotheliomas in asbestosis resemble ovarian cancer in appearance. Intraperitoneal injection of one variety of asbestos produces epithelial changes in the ovaries of guinea pigs and rabbits which are similar to those seen in patients with early ovarian cancer. Six of twelve patients with early ovarian malignant changes show birefringent crystalline material in the ovaries. These observations are compatable with the thesis that asbestos is an etiologic factor in ovarian cancer.