Analysis of asbestos fibers in lung parenchyma, pleural plaques, and mesothelioma tissues of North American insulation workers

Asbestos fibers and ferruginous bodies (FBs) in lung parenchyma, lung cancer tissues, pleural plaques, and pleural and peritoneal mesothelioma tissues from 13 North American insulation workers were analyzed and quantified using an analytical transmission electron microscope and a polarized microscope. Diseases from which these workers suffered included asbestosis, lung cancer, and mesothelioma. They had been occupationally exposed to materials containing chrysotile and amosite; their pathological diagnoses, occupational and cigarette smoking histories, and clinical summaries have been reported. Large numbers of FBs were found in the lungs and small numbers found in extrapulmonary sites. Most of the FBs had cores of amosite fibers. In all instances, lung parenchyma and lung cancer tissues showed chrysotile and amosite fibers in high concentrations (63.1 x 10(6) and 150.2 x 10(6) fibers/g dry tissue as mean values, respectively). Crocidolite fibers were seen in seven of the 13 cases, but in much smaller numbers. Other amphiboles were rarely found. In pleural plaques and in pleural and peritoneal mesothelioma tissues, amosite fibers were markedly fewer in number, whereas chrysotile fibers were seen in similar numbers as in the lungs. No significant differences in the size distribution of asbestos fibers were seen in the different sites. However, the mean widths of chrysotile fibers were thinner than those of amosite fibers. These results strongly suggest that translocation of inhaled asbestos fibers from the lung to other tissues, such as the pleura and the peritoneum, occurs frequently, and that chrysotile may be more actively translocated from the lung, compared to amosite or amphibole asbestos. The likelihood of translocation seems to be strongly related to the thinness of the fibers. Translocated chrysotile fibers may play an important role in the induction of either malignant mesothelioma and/or hyaline plaques, since the asbestos fibers detected in both these sites were mainly chrysotile.

[Asbestos and bronchogenic carcinoma: a search for fibers in the pulmonary tissue of 3 patients with bronchogenic carcinoma]

Based on the highly suspicious radiological findings of exposure to asbestos (case 1) or on a positive occupational history (cases 2 and 3), the authors looked for the presence of fibers in blocks of lung tissue removed in autopsy or surgical biopsies of three cases of bronchogenic carcinoma. The blocks were submitted to sodium hypochloride digestion followed by fiber identification in phase contrast light microscopy. The authors were able to demonstrate the presence of fibres in the three cases. The likelyhood of those carcinomas being caused by exposure to asbestos is very high, as two out of the three cases showed pulmonary fibrosis (cases 1 and 2) and the other case showed typical parietal pleural plaques at thoracotomy.

Relationship between number of asbestos bodies in autopsy lung and pleural plaques on chest X-ray film

We investigated the relationship between number of asbestos bodies and pleural plaques. Using sodium hypochrolite, we examined 400 autopsy lungs and could detect 71 cases whose asbestos bodies were significantly high. We checked pleural plaques on chest x-ray films of these 71 cases and compared the exact plaque at autopsy. By the criteria of Askergren and Szamosi, we classified these into three groups (probable, definite, definite with calcification). This classification is consistent with the pleural plaques found at autopsy. Cases whose pleural plaques were definite (thick) had many more asbestos bodies than indefinite cases. As for occupational histories, there were 23 cases who worked in Japanese Naval shipyards before and during World War II, 14 others in various shipyards, and 14 others who also had a history of asbestos exposure. These 51 patients died more than 30 years after the first asbestos exposure. Twenty had no definite asbestos exposure.

Mineral fiber concentration in lung tissue of mesothelioma patients in Finland

The mineral fibers in lung tissue samples of 19 mesothelioma patients and 15 randomly selected autopsy cases were analyzed using low-temperature ashing, scanning electron microscopy (SEM) and x-ray microanalysis. The fiber concentration ranged from 0.5 to 370 million fibers per gram of dry tissue in the mesothelioma group and from less than 0.01 to 3.2 million fibers per gram of dry tissue in the autopsy group. In 80% of the mesothelioma patients and in 20% of the autopsy cases, the fiber concentration exceeded 1 million fibers per gram of dry tissue. Amphibole asbestos fibers predominated in both groups, and only a few chrysotile fibers were found. In the lungs of six mesothelioma patients, anthophyllite was the main fiber type. The overall analytical precision of sample preparation and fiber counting with SEM was 22%.

Electron microscopic analysis of asbestos body cores from the Belgian urban population

Typical ferruginous bodies considered as asbestos bodies (AB) were collected from the lungs of 19 asbestos-exposed and 25 non-exposed urban subjects. Of the 319 body cores analysed by energy dispersive spectrometry (EDS), 315 were asbestos. The non-asbestos cores were talc and crystalline silica. 89.2% of the asbestos cores were commercial amphiboles (amosite/crocidolite), 7% were chrysotile and 3.8% were non-commercial amphiboles (anthophyllite/tremolite). The commercial amphibole bodies were found in exposed and non-exposed subjects and chrysotile bodies mostly in exposed subjects. The non-commercial amphibole bodies were detected in non-exposed patients with low lung AB levels; this background contamination would be more difficult to detect in lungs containing large amounts of bodies due to occupational exposure. Chrysotile bodies and tremolite/anthophyllite bodies were not observed together. We suggest that in Belgium the source of non-commercial amphiboles exposure is not contamination by chrysotile.

A rapid and simple method of extracting asbestos bodies from lung tissue by cytocentrifugation

During analyses of alkali digested lung tissue for asbestos bodies, we observed that the number of asbestos bodies in the discarded waste frequently exceeded the number in the filtered residue, the number reported in the standard diagnostic method. This observation led to the exploration of alternative techniques that would optimize the recovery of asbestos bodies. We describe a new, simple, and rapid method for extracting asbestos bodies from digested lung tissue using a cytocentrifuge, in which the waste extraction and filtration steps are eliminated. Samples of digested lung tissue are ready for light microscopy after 10 minutes of cytocentrifugation directly onto a glass slide. The standard method was compared with the cytocentrifuge technique using lung tissue from four asbestos-exposed workers and four controls with no known history of exposure. The number of asbestos bodies extracted by the centrifuge method was, on average, seven times higher than the number found with the standard method. A detailed quantitative study was made of the case that had the most asbestos bodies (comparison of the number of asbestos bodies counted in both "residue" and "waste", applying the filtration and cytocentrifuge methods). The number of asbestos bodies found in the discarded waste significantly exceeded the number in the "reportable" filtered residue.

Identification of asbestos fibers within single cells

Identification of asbestos fibers and other mineral particles in tissues is important for the diagnosis of interstitial lung disease. Conventional procedures to identify mineral particles are applicable to tissue digests, homogenates, or thin sections prepared for transmission electron microscopy. Positive identification of mineral particles in these samples is achieved by energy dispersive x-ray analysis or crystalline diffraction patterns. These analytical techniques are difficult to use for identification of long, thin asbestos fibers within cells collected from effusions or by saline lavage. A new preparative procedure is presented which allows intracellular visualization of fibers in these samples. Mice were injected intraperitoneally with 100 micrograms of crocidolite asbestos. After 1 to 30 days, the free peritoneal cell population was collected by saline lavage and allowed to attach to Formvar/carbon coated grids in vitro. Cell spreading was induced by exposure to phorbol-12-myristate-13-acetate for an additional 4 hours. The flattened cells were fixed, dehydrated and air-dried before examination by transmission electron microscopy. This procedure allows direct visualization of intracellular fibers. The characteristic Fe and Si peaks of crocidolite asbestos were confirmed by energy dispersive x-ray analysis. This technique was used to study the kinetics of clearance of asbestos fibers from the free peritoneal macrophage population of mice.

Method for removing the ferruginous coating from asbestos bodies

A new technique for removing the ferruginous coating from ferruginous bodies is described. The tissue from occupationally exposed individuals was digested in bleach and the material collected on a Nuclepore filter. The ferruginous bodies were localized by light microscopy and either cleaned on the marked filter or transferred to a marked area on a clean filter. The chemical treatment consisted of an 8% oxalic acid bath used at various temperatures. It was determined that at 75 degrees C the reaction resulted in removal of the ferruginous coat, leaving an exposed core for further analysis. This procedure overcomes the previous analytical problems of core analysis caused by the ferruginous coating.

Migration of ingested asbestos

Tissue samples from one test and one control baboon were analyzed by transmission electron microscopy for the presence of chrysotile and crocidolite asbestos. The test animal had been gavaged with cumulative doses of 800 mg each of chrysotile and crocidolite asbestos. An earlier evaluation of these tissues led to the conclusion that ingested asbestos fibers do not penetrate the gastrointestinal tract of the baboon and migrate systemically. However, the present study involved more sensitive methodology, and penetration and migration were clearly demonstrated by the recovery of significant levels of asbestos from test stomach, heart, spleen, pancreas, and blood samples.

The distribution and characteristics of asbestos fibers in the lungs of Finnish anthophyllite mine-workers

Measurements of the concentrations and dimensions of uncoated and coated fibers in blocks of tissue taken at the periphery and elsewhere from slices of lungs obtained from two anthophyllite-mine workers are reported. A single block from the lung of a third worker was also analyzed. For the subject examined in most detail, the mean peripheral fiber concentration was greatest in the lower lobe. In the other subject there did not appear to be much variation in fiber concentration with distance from the periphery. The count median lengths of uncoated fibers ranged from about 8 to 12 micron and for coated fibers from 40 to 50 micron. It was apparent that dicing tissue samples, before hypochlorite digestion, led to fracture of the longer uncoated and coated fibers. The results are compared with similar measurements made on the lung of an insulation worker and reported previously.

Identification and counting of asbestos fibers

A combined analytical electron microscopic/optical count method for the determination of airborne asbestos fibers was tested for precision and bias. A modified phase contrast microscopic count method (NIOSH Method 7400) was used to determine total fiber content. The analytical electron microscope (AEM) procedure was added to identify the fraction of amosite asbestos fibers in airborne, laboratory-generated samples containing amosite and wollastonite fibers. Then this fraction was applied to the routine optical counts of all the samples in the set to estimate the asbestos fiber concentration. The effects of sample to sample, wedge to wedge, within wedge and between and counter variability were examined. In addition, the variabilities of the elemental ratio within a fiber and between fibers was also determined to find their possible influence on the ability to identify the fiber as amosite in the presence of other silicate fibers. A precision of 20.1% relative standard deviation (RSD) and a bias of -9.1% for the AEM count method compared with the optical count procedure were found for these mixed fiber samples.

Method for removing the ferruginous coating from asbestos bodies

A new technique for removing the ferruginous coating from ferruginous bodies is described. The tissue from occupationally exposed individuals was digested in bleach and the material collected on a Nucleopore filter. The ferruginous bodies were localized by light microscopy and either cleaned on the marked filter or transferred to a marked area on a clean filter. The chemical treatment consisted of an 8% oxalic acid bath used at various temperatures. It was determined that at 75 degrees C the reaction resulted in removal of the ferruginous coat, leaving an exposed core for further analysis. This procedure overcomes the previous analytical problems of core analysis caused by the ferruginous coating.

Asbestos bodies in bronchoalveolar lavage

Asbestos bodies (AB) were counted in bronchoalveolar lavage (BAL) fluid from 62 patients with suspected asbestos related diseases, 2 patients with known exposure to asbestos but without related disease, and 40 control subjects. BAL fluid contained AB in all patients with obvious exposure (28 of 28), including the 2 without related disease, in most patients with suspected exposure (26 of 28), as well as in 5 of 8 patients without known exposure but with suspicion of asbestos related disease (mesothelioma or pleural plaques). Among the 40 control subjects, the results in 5 were positive but to a low degree (less than 1 AB/ml of fluid). Quantitative analysis correlated with the type of disease: AB counts were higher in patients with interstitial lung disease than in those with benign (p less than 0.02) or malignant (p less than 0.01) pleural disease. Only 9 of 13 patients with mesothelioma had a positive lavage. In conclusion, the finding of AB in BAL fluid correlates with the occupational risk and can disclose unknown exposure better than a questionnaire, but a positive lavage is not a proof of disease. Quantitative differences in AB counts suggest a different pathogenesis for pleural and parenchymal disease.

A procedure for the isolation of amosite asbestos and ferruginous bodies from lung tissue and sputum

A comprehensive scheme is described for isolating amosite asbestos and ferruginous bodies from fixed and unfixed human lung tissue and sputum. This qualitative procedure avoids many of the problems associated with previous isolation techniques and illustrates the advantages of brief bleach digestions. The samples are digested in prefiltered Wright laundry bleach (9.2% sodium hypochlorite), collected on 0.2-microns Nucleopore filters by vacuum filtration, rinsed with distilled water and absolute ethanol, and examined visually for excessive residue. If organic residues are suspected or are known to occur, the sample is treated sequentially with 2% potassium permanganate, 8% oxalic acid, and 9.2% sodium hypochlorite, and rinsed with distilled water and absolute ethanol. The ethanol, potassium permanganate, and oxalic acid steps can be repeated as often as needed until the desired sample volume has been filtered. The entire procedure allows large volumes to be filtered and yields filters that have extremely clean backgrounds. Filtration can be completed in as little as 15 min, as opposed to the hours or days recommended for other procedures. The technique is applicable to specimens fixed in Saccomanno's fixative or glutaraldehyde, and to those in an unfixed state. The procedure does not appear to damage the gross morphology of the amosite fibers, and it does not produce a detectable change in their elemental composition when determined by energy-dispersive X-ray analysis.

Analysis of fibres in human lung tissue

Standard UICC crocidolite fibres and fibres extracted from occupationally exposed human lung tissue have been analysed by scanninng electron microscopy after different preparation procedures. A significant fibre loss has been shown due to the adhesion of fibres to the breakers. Fibres are also discarded during the washing and extraction of the lung tissue samples. The recovery was found to be 30 to 40% both for UICC standard specimens and for lung tissue samples.