Development of a testing method for asbestos fibers in treated materials of asbestos containing wastes by transmission electron microscopy

Appropriate treatment of asbestos-containing wastes is a significant problem. In Japan, the inertization of asbestos-containing wastes based on new treatment processes approved by the Minister of the Environment is promoted. A highly sensitive method for testing asbestos fibers in inertized materials is required so that these processes can be approved. We developed a method in which fibers from milled treated materials are extracted in water by shaking, and are counted and identified by transmission electron microscopy. Evaluation of this method by using asbestos standards and simulated slag samples confirmed that the quantitation limits are a few million fibers per gram and a few μg/g in a sample of 50mg per filter. We used this method to assay asbestos fibers in slag samples produced by high-temperature melting of asbestos-containing wastes. Fiber concentrations were below the quantitation limit in all samples, and total fiber concentrations were determined as 47-170×10(-6) f/g. Because the evaluation of treated materials by TEM is difficult owing to the limited amount of sample observable, this testing method should be used in conjunction with bulk analytical methods for sure evaluation of treated materials.

Peroxidase-like activity of ferruginous bodies isolated by exploiting their magnetic property

Ferruginous bodies (FB) are polymorphic structures whose formation is macrophage dependent, and are composed of a core, which may consist of an asbestos fiber coated with proteins, among which ferritin is the main component. Within ferritin, the ferric and ferrous ions are coordinated as ferrihydrite, which is the main iron (Fe) storage compound. However, when ferritin accumulates in some tissues following Fe overload it also contains magnetite along with ferrihydrite, which endows it with magnetic properties. Recently studies showed that magnetite exerts peroxidase-like activity, and since ferruginous bodies display magnetic properties, it was postulated that these particular structures may also contain magnetite within the ferritin coating, and thus may also exert peroxidase-like activity. Histochemical analysis for peroxidase of isolated FB smears demonstrated positive staining. Samples isolated from 4 different autopsy lung fragments were also able to oxidize 3,3',5,5'-tetramethyl-benzidine to a blue colored compound that absorbs at 655 nm. This activity was (1) azide and heat insensitive with optimal pH from 5 to 6, and (2) highly variable, changing more than 25-fold from one sample to another. These findings, together with evidence that the peroxidase-like activity of ferruginous bodies has a hydrogen peroxide and substrate requirement different from that of human myeloperoxidase, can exclude that this enzyme gives a significant contribution to the formation of FB. Standard Fe-rich asbestos fibers also express a peroxidase-like activity, but this appears negligible compared to that of ferruginous bodies. Strong acidification of standard Fe-containing asbestos fibers or magnetically isolated ferruginous bodies liberates a high amount of peroxidase-like activity, which is probably accounted for by the release of Fe ions. Further, FB also damage mesothelial cells in vitro. Data suggest that FB exert peroxidase-like activity and cytotoxic activity against mesothelial cells, and hence may be an important factor in pathogenesis of asbestos-related diseases.

Comparison of lung asbestos fiber content in cancer subjects with healthy individuals with no known history of occupational asbestos exposure in Korea

To evaluate the effects of environmental asbestos exposure on the inducement of lung cancer, pulmonary asbestos and non-asbestos fiber content was determined in 36 normal Korean subjects and 38 lung cancer subjects with no known occupational history of asbestos exposure. Pulmonary asbestos fiber content was measured by transmission electron microscopy (TEM) with energy-dispersive x-ray analysis after applying a low-temperature ashing procedure. Chrysotile fibers were the major fiber type found in the lungs of the Korean subjects. The asbestos fiber concentrations found in the lungs of normal males (25) and females (11) were 0.26 x 10(6) fibers/g of dry lung tissue and 0.16 x 10(6) fibers/g of dry lung tissue, respectively. The asbestos concentrations found in the lungs of cancer subjects were 0.16 x 10(6) fibers/g of dry lung tissue for 32 males and 0.44 x 10(6) fibers/g of dry lung tissue for 6 females. No statistical difference was found in pulmonary asbestos content between the normal and lung cancer subjects, whereas a statistical difference was noted between normal and lung cancer subjects with respect to lung non-asbestos content, indicating a potential role for non-asbestos fibers being associated with lung cancer.

Asbestos reclamation at a disused industrial plant, Bagnoli (Naples, Italy)

Asbestos reclamation works were carried out at a disused industrial plant (157,000 m(2)) in Bagnoli, a high population density area of Naples. The case-study here presented recommends a new reclamation procedure that is not usually provided for by current international standards. To this purpose, a specific innovative cleaning machine (Safecar) was built in order to control the reclamation procedures also in non-confined areas. An accurate identification was planned and worked out of the various types of materials (10,111 t) present within the area, and this allowed a thorough mapping of the site to be decontaminated. Besides these reclamation activities, which were carried out in both confined and open sites, each material was cleaned, collected and encapsulated following diversified procedures, according to their characteristics. Moreover, the evaluation of airborne asbestos fibre concentrations, both within and outside the decontaminated area, assured a strict respect of environmental safety level.

Synchronous diffuse malignant mesothelioma and carcinomas in asbestos-exposed individuals

AIMS

The development of synchronous diffuse malignant mesothelioma and carcinoma in individuals exposed to asbestos is rare. We report nine cases and discuss the medico-legal implications.

METHODS AND RESULTS

Five hundred patients seeking compensation for asbestos-related diffuse malignant mesothelioma were reviewed with access to post-mortem data. The study group comprised cases in which a second (non-mesothelial) neoplasm was identified. The study group comprised eight males, one female, mean age 68 years (range 60-75). All individuals gave a history of asbestos exposure. Synchronous malignant mesothelioma with carcinoma was identified in 9/500 (1.8%). Eight malignant mesotheliomas were pleural, one was primary peritoneal in origin. By morphological subtyping there were four epithelioid, three biphasic and two sarcomatoid mesotheliomas. In 6/9 (67%) the second tumour was a primary bronchogenic carcinoma (three adenocarcinomas, two squamous cell carcinomas and one small-cell carcinoma). In 3/9 (33%) the second tumour was a non-bronchogenic carcinoma (colonic, pancreatic and breast ductal adenocarcinoma). No other neoplasms were identified in the cohort of malignant mesotheliomas studied. Five persons had pathological evidence of asbestosis (four had bronchogenic carcinomas, one colorectal adenocarcinoma). Two persons with non-bronchogenic carcinomas had identifiable asbestos bodies but no interstitial fibrosis. In two cases the second neoplasms (primary bronchogenic squamous cell and small-cell carcinomas) were associated with diffuse interstitial fibrosis but no asbestos bodies were seen on light microscopy. In each case transmission electron microscopic mineral analysis revealed an asbestos fibre burden within the background population range for control subjects and well below that seen in cases of established asbestosis. These cases were considered to represent cryptogenic fibrosing alveolitis in subjects with a history of asbestos exposure.

CONCLUSIONS

Synchronous malignant mesothelioma with carcinomas in asbestos-exposed workers is rare and identified in 1.8% of 500 malignant mesotheliomas in this series. In most cases the carcinoma represents a primary bronchogenic neoplasm. Primary lung carcinomas are recognized to be asbestos related only when occurring in association with asbestosis. In this series this combination (bronchogenic carcinoma and asbestosis) was seen in four (0.8%) cases. In post-mortem cases for possible malignant mesothelioma it is important to identify any other neoplasia and determine whether it is related to asbestos. Their presence impact upon anticipated life expectancy and in the presence of malignant mesothelioma will affect the compensation settlement.

Anthophyllite exposure and endemic pleural plaques in Kumamoto, Japan

OBJECTIVES

This study explored the high prevalence of pleural plaques in the town of Matsubase in Kumamoto, Japan.

METHODS

Small-size chest X-ray film was used for screening, and all persons with pleural plaques were confirmed by computed tomography (CT). The prevalence rate of pleural plaques in the 4 districts of Matsubase and its surrounding towns and cities were also examined. The age-adjusted mortality rate for lung cancer in this town was compared with that of its surrounding towns and cities.

RESULTS

Pleural plaques were found in 1357 persons (724 men and 633 women) among the inhabitants who were more than 20 years of age in Matsubase between 1988 and 1993. CT scans ascertained 938 cases with pleural plaques among the 11 14 persons who participated. Thus at least 9.5% of the inhabitants over 20 years of age in this town had pleural plaques. The neighboring towns had a higher rate than the more distant towns. A large-scale open-cast asbestos mine and mill had been in operation in Matsubase between 1883 and 1970. Mineral analysis revealed anthophyllite fibers. Most of the plaques were found in persons who had never worked in the mine or mill.

CONCLUSIONS

The high prevalence of pleural plaques in Matsubase was due to anthophyllite exposure, mainly environmental. No mesotheliomas were found, however. These findings agree with those from an earlier study from Finland.

Analysis of asbestos fiber burden in lung tissue from mesothelioma patients

Mesothelioma is a rare neoplasm that occurs most frequently in individuals with previous asbestos exposure. Differences for risk of development of asbestos-related mesothelioma and lung cancer have been attributed to the various types of asbestos, as well as to the dimension of the inhaled fibers. In the present study, 55 individuals with the pathological diagnosis of mesothelioma were evaluated as to ferruginous body and fiber content in lung tissue. The procedures used in the analysis included tissue digestion and analysis of the collected material for ferruginous bodies by light microscopy and for uncoated fibers by analytical transmission electron microscopy. Forty-six of the samples had ferruginous body concentrations of over 1000/per gram dry weight of lung tissue. The majority of the cores of these ferruginous bodies were amosite. Likewise, the most common uncoated asbestos fiber in the tissue was amosite. Only a small percentage of each type of asbestos would have been visible by light microscopy or even potentially by electron microscopy if the magnification was not sufficient to detect those with thin (< 0.2 micron) diameters. The consistent finding in most of the cases was a considerable presence of asbestos, often of mixed types.

[Lung cancers attributable to asbestos on a pathological basis]

More than 1,000 asbestos bodies/gram dry weight (AB/gdw) were found by light microscopy in lung tissues, out of 429 non selected cases of pulmonary carcinoma (264 from surgery and 165 from autopsy). Asbestosis was detected by histology in 28% of the cases with AB > 1,000/gdw (in 19% of the surgical cases, and in 38% of the autopsy cases). A proportion of 4% of the total cases may be related to asbestos exposure.

[Asbestos fiber count in extra-pulmonary tissues]

Most autoptic tissues of three men (two with pulmonary asbestosis and one without any exposure to asbestos) were analyzed by transmission electron microscopy and energy dispersion spectrometry for the quantitative and qualitative evaluation of asbestos fibers. Preliminary results indicate that only in cases with occupational exposure were found asbestos fibers (in lung, pleura , bladder, kidney and liver). These results allow interesting speculations on some environmental pathogenetic questions and deserve further investigations.

Relationships between ferruginous bodies and uncoated asbestos fibers in lung tissue

Tissue was obtained from two American groups. The tissue was defined by ferruginous body levels of either < or = 1000 or > 1000 ferruginous bodies/g dry weight, and tissue was evaluated by light microscopy and analyzed by analytical transmission electron microscopy. Tissue was bleach digested, and uncoated asbestos fibers were classified with respect to type and size. In addition, some ferruginous body cores were analyzed. There was a wide range of uncoated fibers associated with each ferruginous body. A relationship was found between amosite fibers and ferruginous bodies. Other asbestos types were not associated significantly with the development of ferruginous bodies. Uncoated crocidolite fibers were not detected in these samples; this result further emphasizes the under-appreciated exposure of Americans to amosite. The levels of ferruginous bodies in both groups suggest exposures above those expected in the general population. Uncoated chrysotile levels were below the ranges reported previously for some general populations. The data suggest that there is a wide variation in the ratio of uncoated to coated fibers and that the amphibole in the United States is more likely to be amosite than crocidolite.

Asbestos bodies in the sputum of workers exposed to environmental pollution

The diseases related to asbestos exposure (pulmonary fibrosis, broncogenic carcinoma and mesothelioma) are of widespread interest and involve different socio-economic groups of subjects. Since these pathologies have a wide diffusion in the industrial world, we carried out an investigation on two populations occupationally exposed to air pollution and asbestos fibre inhalation (164 traffic policemen of the municipal district of Rome and 218 railwaymen) and on a control group (119 residents in a rural district of Perugia) for the detection of asbestos bodies in the sputum. The results obtained from traffic policemen and railwaymen workers differred significantly from those of the control group. The presence of asbestos bodies in traffic policemen seems to be determined by a strong synergetic effect between gaseous urban pollution, cigarette smoking habits and asbestos dust arising from car brakes and building materials, whereas, in railwaymen it seems to be more directly correlated to exposure.

Asbestos body formation in the human lung: distinctions, by type and size

The fraction of fibers coated in a total of 3,800 asbestos fibers from 38 patients with disease related to asbestos (100 fibers per patient) was determined, according to asbestos fiber type and size parameters. Among the 3,800 fibers, 638 (16.8%) were coated and 3,162 were uncoated. All fibers were analyzed at 2,000 x magnification (lower limit of detection: 2 microns for length and 0.06 microns for diameter). The diameter of the totally coated fibers (28.4% of total bodies; 181/638) was not measured. The percentage of coated fibers varied with the asbestos type; it was 27.1% (335/1235) for amosite fibers, 16.0% (228/1423) for crocidolite, 6.6% (60/908) for tremolite or actinolite, 6.5% (14/214) for anthophyllite, and 5% (1/20) for chrysotile fibers. Most coated fibers were longer than 10 microns and had an aspect ratio (length/diameter) of more than 20. Approximately 60% of coated fibers had an aspect ratio of more than 100. The longer the fiber, the greater the percentage of coated fibers, regardless of diameter. The increase in the percentage associated with length was more marked in fibers with a smaller diameter; the percentage of coated fibers was, therefore, greater in fibers 30 microns or less in diameter. However, in fibers longer than 30 microns, the relationship to percentage of coated fibers was not as clear, and the diameter was less important. Accordingly, the fibers with high aspect ratios, particularly long fibers, tended to show asbestos body formation. The percentage of long fibers was highest in amosite, and the percentage of fibers with an aspect ratio of more than 100 was highest in amosite and crocidolite.(ABSTRACT TRUNCATED AT 250 WORDS)

Asbestos exposure and pulmonary fiber concentrations of 300 Finnish urban men

OBJECTIVES

The aim of the study was to determine the pulmonary concentrations of mineral fibers in the Finnish male urban population and to evaluate the analysis of pulmonary fiber burden by scanning electron microscopy (SEM) as an indicator of past fiber exposure.

METHODS

The pulmonary concentration of mineral fibers was determined by SEM and compared with occupational history for a series of 300 autopsies of urban men aged 33 to 69 years.

RESULTS

The concentration of fibers (f) longer than 1 micron ranged from < 0.3 to 163.10(6) per gram of dry tissue (f.g-1). Asbestos fiber concentrations exceeding 1.10(6) f.g-1 were observed in 33% of the cases with probable occupational exposure to asbestos and 1% of the cases with unlikely occupational exposure. Even asbestos fiber concentrations of 0.3 to 1.10(6) f.g-1, especially of crocidolite-amosite fibers, were rare among the men with unlikely occupational exposure. Fiber concentrations exceeding or equaling 1.10(6) f.g-1 were 10 times more frequent among the men more than 60 years of age as compared with those less than 40 years of age. Inorganic fibers other than asbestos had a weaker correlation with occupational history and age. Smoking habits had no significant effect on the pulmonary fiber counts.

CONCLUSIONS

Asbestos fiber concentrations exceeding 1.10(6) f.g-1 are highly indicative of past occupational exposure to asbestos. The distribution of fiber concentrations in the different age groups of this study indicated decreasing asbestos exposure in Finland since the 1970s.

Asbestos fiber analysis in seven asbestosis cases

Asbestos bodies and fibers deposited in the lungs of seven asbestosis cases were counted after tissue digestion. The types and sizes of 100 asbestos fibers for each case were also analyzed. Asbestos bodies were counted with an optical microscope at 100x magnification, and asbestos fibers were counted with a transmission electron microscope (TEM) at 2000x magnification. Most asbestos fibers detected with TEM were longer than 3 microns (92.5%) and thicker than 0.1 microns (92.3%). Short fibers less than 2 microns--both chrysotile and amphiboles, as well as long, thin fibers less than 0.06 microns--would be missed at 2000x (TEM). An average of 1.37 (0.081-5.5) x 10(6) asbestos bodies and 164.8 (0.55-610) x 10(6) asbestos fibers per 5 g wet (0.88 g dry) lung tissue were found, and these values are higher than what was reported in mesothelioma cases without asbestosis that were reported previously. More than 13 (average = 266.2) asbestos bodies were found in a 4-micron-thick tissue section (average area = 3.24 cm2). One asbestos body in a section equaled approximately 5,000 per 5 g wet lung tissue. The intensity of fibrosis was minimal in one case, mild in four, moderate and severe in one each, and the intensity was correlated with the number of asbestos bodies and fibers. The fibrosis in the severe case may have been intensified by repeated infection. Crocidolite fibers were found most frequently (84.7%), were thin, and had a high aspect ratio by our counting rules. Crocidolite with a high aspect ratio may be most fibrogenic in the lung.

Extreme airborne asbestos concentrations in a public building

Fibre concentrations of asbestos were measured in the air of a communal dining room in which the damaged ceiling had a sprayed on coating of insulation containing asbestos. The average concentration of crocidolite asbestos fibres was 4 f/cm3, 20 times the highest air concentration that appears to have been reported previously for a public building. It is concluded that although air concentrations of asbestos fibres in public buildings containing asbestos insulation materials are usually low, high concentrations can occur. This may have implications for the risk of exposed persons developing diseases associated with asbestos.

Fibrous minerals in the lungs of mesothelioma patients: comparison between data on SEM, TEM, and personal interview information

To determine and compare the fiber types and size distributions in the lung tissue of mesothelioma patients in Finland, samples from 29 patients with known work history were analyzed with transmission electron microscopy (TEM) and X-ray microanalysis. Compared with the earlier results using scanning electron microscopy (SEM), the fiber concentrations were about three times as high and ranged from 0.1 million to 5,200 million fibers per gram of dry tissue. In 15 patients (52%), crocidolite/amosite were the dominating fiber types, representing more than 70% of all fibers. Anthophyllite asbestos was the most prevalent fiber type in eight patients (28%), and it was found in the samples of 13 patients (45%). One-half of the anthophyllite fibers were longer than 5 microns, whereas other fiber types were somewhat smaller.

Asbestos-associated pleural mesothelioma in school teachers: a discussion of four cases

The causal relationship between malignant mesothelioma and exposure to asbestos is well established. In part as a result of that association, much public attention has focused on asbestos abatement in buildings, such as public schools, in which that asbestos was used as a construction material. The present communication is a report of four cases of malignant mesothelioma in school teachers whose only apparent exposure to asbestos was in the schools in which they taught. The concerns raised by this report are also discussed.

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.