Asbestos fibres in bronchoalveolar lavage fluid from asbestos workers: examination by electron microscopy

The uncoated and coated fibre load in bronchoalveolar lavage (BAL) fluid was assessed using light microscopy, scanning electron microscopy, and x ray microanalysis in 15 subjects with previous, unprotected exposure to asbestos, including three with clinical and radiological evidence of asbestosis, and in 13 urban dwelling control subjects with no known occupational exposure to asbestos. The mean ferruginous body count per ml BAL fluid in asbestos exposed subjects as determined by light microscopy was 52 (range 0-333). No ferruginous bodies were detected in control subjects. The mean fibre count per ml BAL fluid in asbestos exposed subjects as determined by electron microscopy was 793 (133-3700), significantly greater than 239 (44-544) in controls (p less than 0.05). Electron microscopic counts correlated with duration of previous exposure to asbestos (r = 0.47, p less than 0.05) and with percentage neutrophil counts (r = 0.53, p less than 0.025). There was no relation between electron microscopic fibre counts and light microscopic ferruginous body counts. In 11 asbestos exposed cases x ray microanalysis confirmed the presence of asbestos and in six the asbestos fibre type was clearly identified. Of five subjects showing no asbestos bodies by light microscopy, all showed fibres by electron microscopy, and in three cases the presence of asbestos was confirmed by microanalysis. Among control subjects, fibres were either large organic fibres or smaller particles which microanalysis showed were not asbestos. In only one control case were a few fibres identified which were confirmed as asbestos fibres on microanalysis. Electron microscopic examination of BAL fluid may confirm past exposure to asbestos and probably gives a crude quantitative estimate of asbestos load.     

Asbestos fibres in bronchoalveolar lavage fluid from asbestos workers: examination by electron microscopy.

The uncoated and coated fibre load in bronchoalveolar lavage (BAL) fluid was assessed using light microscopy, scanning electron microscopy, and x ray microanalysis in 15 subjects with previous, unprotected exposure to asbestos, including three with clinical and radiological evidence of asbestosis, and in 13 urban dwelling control subjects with no known occupational exposure to asbestos. The mean ferruginous body count per ml BAL fluid in asbestos exposed subjects as determined by light microscopy was 52 (range 0-333). No ferruginous bodies were detected in control subjects. The mean fibre count per ml BAL fluid in asbestos exposed subjects as determined by electron microscopy was 793 (133-3700), significantly greater than 239 (44-544) in controls (p less than 0.05). Electron microscopic counts correlated with duration of previous exposure to asbestos (r = 0.47, p less than 0.05) and with percentage neutrophil counts (r = 0.53, p less than 0.025). There was no relation between electron microscopic fibre counts and light microscopic ferruginous body counts. In 11 asbestos exposed cases x ray microanalysis confirmed the presence of asbestos and in six the asbestos fibre type was clearly identified. Of five subjects showing no asbestos bodies by light microscopy, all showed fibres by electron microscopy, and in three cases the presence of asbestos was confirmed by microanalysis. Among control subjects, fibres were either large organic fibres or smaller particles which microanalysis showed were not asbestos. In only one control case were a few fibres identified which were confirmed as asbestos fibres on microanalysis. Electron microscopic examination of BAL fluid may confirm past exposure to asbestos and probably gives a crude quantitative estimate of asbestos load.     

Biopersistence of cerium in the human respiratory tract and ultrastructural findings

For diagnostic purposes, mineralogical analysis was performed in bronchoalveolar la-vage fluid and lung tissue from a 58-year-old patient previously exposed to asbestos and rare earth dusts. No significant retention of asbestos was demonstrated in lung tissue by light microscopy (asbestos bodies) or transmission electron microscopy analysis (un-coated fibers). Particles containing rare earth (cerium, lanthanum) and phosphorus were identified in alveolar macrophages in bronchoalveolar lavage fluid, and cerium-containing particles accounted for 70% of particles observed in the lung tissue. Ultrastructural analysis of lung tissue revealed the presence of particles containing cerium and phosphorus in interstitial macrophages and elastic fibers. These results suggest that rare earth is metabolized and should be considered as biopersistent in the human respiratory tract, since occupational inquiries revealed that exposure to cerium oxide abrasive powder had ceased at least 15 years earlier.     

Retention of Asbestos Bodies in the Lungs of Welders

Examination of asbestos bodies (AB) retained in the lungs is a useful way of assessing past occupational exposure to this material. AB retention has been extensively studied in workers directly exposed to asbestos, but less so in those end users, such as welders, who use asbestos-containing products. We therefore retrospectively studied AB retention in 211 welders, for whom biological testing procedures had been requested by a chest physician, between 1988 and 1991. Optical microscopy of AB was performed on samples of sputum (40 subjects), bronchoalveolar lavage fluid (BAL) (147 subjects), and lung tissue obtained after thoracotomy (38 subjects). Information on previous jobs and exposure was obtained using a questionnaire (the mean duration of welding activities was 16.6 years). Eighty-two subjects (38.9%) had elevated lung retention of AB in all the samples studied. Significant AB retention occurred in only 30% of sputum samples, but in 40.1% of BAL samples and 39.5% of lung tissue samples. The duration of welding activities correlated with the density of AB in BAL or lung tissue (r = 0.31, p < 0.01 and r = 0.49, p < 0.05, respectively). On the basis of the questionnaire, only two of the welders with significant AB retention had other occupational exposure to asbestos. Our findings suggest that welding activities may increase lung retention of AB, and consequently might produce higher risks of fibrotic and/or malignant pulmonary diseases. These potential risks need to be brought to the attention of doctors; a longitudinal follow-up may also be warranted in such populations, even after individuals have ceased their welding jobs.     

The presence of asbestos bodies in induced sputum as an indicator of asbestos exposure

BACKGROUND: Very few references on the usability of presence of asbestos bodies (AB) in induced sputum as an indicator of asbestos exposure are to be found in the scientific literature. OBJECTIVES: The purpose of this study was to prove whether the presence of AB in induced sputum is a valid assessor of asbestos exposure. METHOD: This was achieved by comparing the above-mentioned method with the search for AB in bronchoalveolar lavage (BAL) fluid and repeating the trials over time in order to study the reproducibility of the results. Results: There was good agreement of results for the presence/absence of AB in induced sputum and in BAL among subjects who were environmentally exposed and those with 'a medium-high risk occupational exposure (100%), and poor agreement (66%) among subjects with a low risk occupational exposure. Agreement of results regarding the amount of particles per test was low. The method showed a sufficient reproducibility level (Cohen K=0.5). CONCLUSION: Although the presence of asbestos bodies in induced sputum cannot replace bronchoalveolar lavage, it can however be used as a screening test for selecting subjects who should undergo BAL.     

Sarcoid reaction observed in a worker with a history of asbestos exposure

Bilateral hilar and mediastinal lymphadenopathy was observed in a 32-year-old man who had been engaged in asbestos spraying for 16 years. Lymph nodes obtained from Daniel's biopsy revealed tissue reaction compatible with sarcoidosis. On the other hand, a large number of asbestos particles were detected in the lung tissue from transbronchial lung biopsy and in bronchoalveolar lavage fluid, but no epithelioid granuloma was observed in the lung tissue. Various immunoserological findings such as PPD skin test, serum angiotensin converting enzyme activity, serum beta-glucuronidase and lysozyme level, serum antinuclear antibody, lymphocyte subset of blood and bronchoalveolar lavage fluid were inconsistent with sarcoidosis. However, lymph node enlargement and immunological abnormalities in this patient may be related to asbestos exposure and may not have occurred merely by chance.     

Asbestos exposure during uncontrolled removal of sprayed-on asbestos

Asbestos-containing materials in place in buildings, especially sprayed-on asbestos, are still an important health threat. Clearance of these materials has to be operated by specifically trained workers wearing specific individual protection suits after containment of the contaminated area. Good work practices are, however, not always applied. We report the case of two workers hired for ～1 week to remove sprayed-on amosite asbestos during the remodeling of a former industrial hall. Regulatory protective equipments were not used. A legal action was initiated after disclosure of the working conditions. Medical examinations were performed 18 and 22 months after exposure. Workers denied any other asbestos exposure. Lung function tests and chest computed tomography scans were normal. Very high levels of asbestos fibers and bodies were discovered on mineralogical analysis of bronchoalveolar lavage fluid (BALF) by phase contrast light microscopy and analytical electron microscopy. All fibers were amosite. An extrapolation considering duration of exposure, breathing pattern, and BALF fiber content suggests that the workers were exposed to airborne fiber concentrations in the range from several tens to about a hundred World Health Organization fibers per milliliter air. In conclusion, exposures to historical airborne fiber levels prevailing half a century ago may still occur today when the work regulations are not applied. In these conditions, even very short exposures may result in considerable lung fiber retention in case of amphibole exposure with the subsequent risk for developing asbestos-related diseases. Fiber analysis in BALF is useful to clarify such exposures.     

Analysis of ferruginous bodies in bronchoalveolar lavage from foundry workers.

Classical ferruginous bodies in tissue samples are considered to be markers of past exposure to asbestos. Recent studies have shown that the presence of ferruginous bodies in bronchoalveolar lavage (BAL) fluid correlates with past exposure to asbestos and offers a more sensitive reference than occupational history. Lavage samples from five subjects who had worked in foundries were evaluated by light microscopy for the presence of ferruginous bodies and by transmission electron microscopy for both characterisation of the uncoated fibre burden and analysis of the cores of the ferruginous bodies. All samples at lower magnification (light microscopy (200 x)) contained ferruginous bodies that were externally consistent with asbestos bodies. At higher magnification (400 x), a separate population from this group could be identified by the presence of a thin black ribbon. Transmission electron microscopy of the core materials of ferruginous bodies and comparable uncoated particulates supported the reliability of higher magnification light microscopy for distinguishing most of those non-asbestos cores; however, a population of transparent non-asbestos cored ferruginous bodies were also shown to exist.     

Asbestos content of lung tissue in asbestos associated diseases: a study of 110 cases

Diseases associated with asbestos exposure include asbestosis, malignant mesothelioma, carcinoma of the lung, and parietal pleural plaques. In this study the asbestos content of lung tissue was examined in groups of cases representing each of these diseases and in several cases with non-occupational idiopathic pulmonary fibrosis. Asbestos bodies (AB), which are the hallmark of asbestos exposure, were present in the lungs of virtually everyone in the general population and present at increased levels in individuals with asbestos associated diseases. The highest numbers of AB occurred in individuals with asbestosis, all of whom had levels greater than or equal to 2000 ABs/g wet lung tissue. Every case with a content of 100,000 ABs/g or higher had asbestosis. Intermediate levels occurred in individuals with malignant mesothelioma and the lowest levels in patients with parietal pleural plaques. There was no overlap between the asbestos content of lung tissue from patients with asbestosis and those with idiopathic pulmonary fibrosis. Lung cancer was present in half the patients with asbestosis, and the distribution of histological patterns did not differ from that in patients with lung cancer without asbestosis. The asbestos body content in patients with lung cancer was highly variable. Control cases had values within our previously established normal range (0-20 ABs/g). There was a significant correlation (p less than 0.001) between AB counted by light microscope and AB and uncoated fibres counted by scanning electron microscopy. The previous observation that the vast majority of asbestos bodies isolated from human tissues have an amphibole core was confirmed.     

Asbestos bodies in lung tissue following exposure to crocidolite

A series of 206 necropsies in Western Australia (WA) have had routine counts made of asbestos bodies in samples of lung tissue using conventional light microscopy. Thirty-two cases had worked in the asbestos industry at Wittenoom, WA and (log) counts of asbestos bodies in their lung tissue correlated well with estimates of their (log) cumulative airborne exposure to crocidolite fibers (r = 0.60). There was no association between the number of asbestos bodies and time since exposure to asbestos ceased. In subjects without known exposure to asbestos, there was a weak but nonsignificant increase in number of asbestos bodies with increasing age, with 26% of cases having no asbestos bodies present. It is concluded that the relatively simple technique of light microscopy for counting of asbestos bodies in lung tissue provides a reliable indication of the level of past occupational exposure to crocidolite in subjects whose exposure has been only to crocidolite. This could be extremely useful in follow-up studies of cohorts that lack reliable measures of airborne exposure to crocidolite asbestos.     

Asbestos content of lung tissue in asbestos associated diseases: a study of 110 cases.

Diseases associated with asbestos exposure include asbestosis, malignant mesothelioma, carcinoma of the lung, and parietal pleural plaques. In this study the asbestos content of lung tissue was examined in groups of cases representing each of these diseases and in several cases with non-occupational idiopathic pulmonary fibrosis. Asbestos bodies (AB), which are the hallmark of asbestos exposure, were present in the lungs of virtually everyone in the general population and present at increased levels in individuals with asbestos associated diseases. The highest numbers of AB occurred in individuals with asbestosis, all of whom had levels greater than or equal to 2000 ABs/g wet lung tissue. Every case with a content of 100,000 ABs/g or higher had asbestosis. Intermediate levels occurred in individuals with malignant mesothelioma and the lowest levels in patients with parietal pleural plaques. There was no overlap between the asbestos content of lung tissue from patients with asbestosis and those with idiopathic pulmonary fibrosis. Lung cancer was present in half the patients with asbestosis, and the distribution of histological patterns did not differ from that in patients with lung cancer without asbestosis. The asbestos body content in patients with lung cancer was highly variable. Control cases had values within our previously established normal range (0-20 ABs/g). There was a significant correlation (p less than 0.001) between AB counted by light microscope and AB and uncoated fibres counted by scanning electron microscopy. The previous observation that the vast majority of asbestos bodies isolated from human tissues have an amphibole core was confirmed.     

Assessment of asbestos exposure via mineralogical analysis of bronchoalveolar lavage fluid

BACKGROUND: Mineralogical analysis of bronchoalveolar lavage fluid (BALF) by electron microscopy could be the most suitable method for assessing asbestos exposure. However, it has been claimed that there is not a standardized or systematic approach to the subject of mineralogical analysis. OBJECTIVES: The aim of the study was to evaluate mineralogical analysis of BALF by transmission electron microscopy (TEM) as biomarker of asbestos fibre load. METHODS: BALF was examined in 193 exposed workers (189 men and 4 women) and in 84 patients (65 men and 19 women) who underwent diagnostic fibreoptic bronchoscopy for various clinical purposes. Asbestos bodies (AB) in BALF were counted with a phase contrast microscope, while fibres were counted and analysed by TEM. RESULTS: Fibre counting by TEM showed a significant difference in the two populations (two tailed Mann-Whitney U test, p=0.0044), since it was positive in all exposed subjects. Only 75.1% of the exposed population was positive for asbestos bodies (AB). Subjects who had been exposed over a long time period had higher concentrations of fibres than subjects who had been exposed more recently probably because of higher exposure in the past. CONCLUSIONS: The study confirms the results of a previous study on a limited number of subjects. Fibre concentrations in BALF can be considered as a reliable biomarker of past asbestos exposure even after many years after cessation of exposure.     

Quantitative analysis of asbestos burden in women with mesothelioma

BACKGROUND: Lung tissue from 15 women who died from mesothelioma was evaluated for tissue burden of ferruginous bodies and uncoated asbestos fibers. The group contained individuals who had occupational exposure to asbestos and others had family members whose work history included vocations where contact with asbestos containing materials occurred. METHODS: Tissue samples from tumor free lung were digested and filtered and then investigated for ferruginous bodies by light microscopy and asbestos and non-asbestos fibers by analytical transmission electron microscopy (ATEM). Size and type of fibers were also analyzed. RESULTS: Asbestos bodies were found in 13 of the 15 samples and asbestos fibers were found in all cases. The most commonly found uncoated asbestos fiber in these individuals was amosite whereas tremolite was the second most commonly found form. The asbestos fiber burden in these females was often of mixed types. CONCLUSIONS: The asbestos body and fiber burden in these cases show variation in tissue burden. Some cases in this study had appreciable burden, which was attributed to secondhand exposure from occupationally exposed family members. Mesothelioma can occur also in individuals with comparatively low tissue burdens of asbestos.     

Asbestos exposure assessment by mineralogical analysis of bronchoalveolar lavage fluid

Mineralogical analysis of bronchoalveolar lavage fluid (BALF) by electron microscopy can represent the most suitable method for assessing asbestos exposure. However, it has been claimed that no standardized or systematic approach to the subject of mineralogical analysis exists. This study aimed to evaluate BALF mineralogical analysis by transmission electron microscopy as biomarker of asbestos fiber load. BALF was examined in 108 exposed workers and 57 patients who underwent diagnostic fiberoptic bronchoscopy for various clinical purposes. Asbestos bodies in BALF were counted with a phase-contrast microscope. Fibers were counted and analyzed by transmission electron microscopy, which showed a significant difference between the two populations and positive results for all exposed subjects. Only 82.2% of the exposed population tested positive for asbestos bodies. Subjects with long-term exposure had higher concentrations of fibers than did those with more recent exposure, probably because of the higher workplace exposure levels in the past. The results of the study confirm that fiber concentration in BALF can be considered as a reliable biomarker of past asbestos exposure, even many years after the end of exposure.     

Fibres and asbestos bodies in bronchoalveolar lavage fluids of asbestos sprayers.

The alveolar content of fibres and asbestos bodies was assessed by bronchoalveolar lavage (BAL) in 21 asbestos sprayers. Transmission and scanning electron microscopy (TEM and SEM) and two light microscopical (LM) methods, cytocentrifugation, and Millipore filtration were used. The subjects had been exposed mainly to crocidolite asbestos for an average of 2.8 (range 0.2-13) years in 1950-75. The mean (median) total fibre count (of asbestos bodies and uncoated fibres) per ml of BAL fluid was 5500 (2800) by TEM and 2900 (1000) by SEM. The mean (median) count of asbestos bodies per ml with LM was 810 (500) with cytocentrifugation and 750 (480) with Millipore filtration, 840 (320) by TEM, and 1750 (420) by SEM. The mean proportion of coated fibres was 35% by TEM and 45% by SEM. The mean length of the coated fibres was 22 (range 4-65) microns by TEM and 34 (range 4.5-170) microns by SEM. The total fibre count exceeded 1000 fibres per ml in 70% of the cases by TEM. Asbestos body counts exceeded 1 per ml in 95% of the cases by LM. The fibre counts by SEM were in good accordance with counts by TEM except in a few cases in which the TEM result was considerably higher. In these cases the proportion of coated fibres was also low. All four counting methods appeared to give consistent results in heavily exposed cases when fibre load in the lungs was high. The counting of asbestos bodies may, however, underestimate the total alveolar fibre load in some cases.     

Fibres and asbestos bodies in bronchoalveolar lavage fluids of asbestos sprayers.

The alveolar content of fibres and asbestos bodies was assessed by bronchoalveolar lavage (BAL) in 21 asbestos sprayers. Transmission and scanning electron microscopy (TEM and SEM) and two light microscopical (LM) methods, cytocentrifugation, and Millipore filtration were used. The subjects had been exposed mainly to crocidolite asbestos for an average of 2.8 (range 0.2-13) years in 1950-75. The mean (median) total fibre count (of asbestos bodies and uncoated fibres) per ml of BAL fluid was 5500 (2800) by TEM and 2900 (1000) by SEM. The mean (median) count of asbestos bodies per ml with LM was 810 (500) with cytocentrifugation and 750 (480) with Millipore filtration, 840 (320) by TEM, and 1750 (420) by SEM. The mean proportion of coated fibres was 35% by TEM and 45% by SEM. The mean length of the coated fibres was 22 (range 4-65) microns by TEM and 34 (range 4.5-170) microns by SEM. The total fibre count exceeded 1000 fibres per ml in 70% of the cases by TEM. Asbestos body counts exceeded 1 per ml in 95% of the cases by LM. The fibre counts by SEM were in good accordance with counts by TEM except in a few cases in which the TEM result was considerably higher. In these cases the proportion of coated fibres was also low. All four counting methods appeared to give consistent results in heavily exposed cases when fibre load in the lungs was high. The counting of asbestos bodies may, however, underestimate the total alveolar fibre load in some cases.     

Alveolar fiber load in asbestos workers and in subjects with no occupational asbestos exposure: an electron microscopy study

The alveolar fiber load was evaluated by bronchoalveolar lavage and by scanning and transmission electron microscopy (SEM and TEM) in 50 subjects with or without occupational exposure to asbestos. The concentration of asbestos fibers in bronchoalveolar lavage was significantly higher in the groups of people currently and formerly occupationally exposed, compared to the concentration found in people only exposed environmentally, despite wide interindividual variation within the groups. Nonasbestos inorganic fibers were present in all groups, but the concentrations did not differ significantly. Both in people occupationally exposed and in those only environmentally exposed, the alveolar load consisted mainly of ultrashort and ultrathin fibers, which can be studied only with TEM. In fact, the percentage of fibers greater than 5 micron long was only around 15% in the occupationally exposed and was minimal in those only environmentally exposed. The geometric mean diameters of asbestos fibers retained in the alveoli ranged from 0.05 micron for chrysotile to 0.15 micron for amphiboles.     

Quantitative comparison of asbestos and talc bodies in an individual with mixed exposure

Tissue from an individual with a history of exposure to asbestos and other dust was referred for particulate analysis. The digested material was reviewed by light microscopy to establish the numbers of ferruginous bodies per gram of tissue. Typical asbestos bodies were found at levels consistent with occupational exposure. A second type of elongated ferruginous body was formed on a thicker transparent core which suggested the minerals were sheet silicates. The number of ferruginous bodies with nonasbestos cores was over four times the number of asbestos cored ferruginous bodies. Electron microscopy was used to confirm the core composition of both populations and also to establish the levels of uncoated fibers. The nonasbestos ferruginous bodies were predominantly formed on talc.     

Measurement of asbestos fibre concentrations in fluid of repeated bro-choalveolar lavages of exposed workers

OBJECTIVES: The aim of this study was to assess the reliability of asbestos fibre concentration in bronchoalveolar lavage fluid (BALF) by carrying out the mineralogical analysis of BALF at different times in the same patient and comparing the results. METHODS: Twenty two patients underwent diagnostic fibreoptic bronchoscopy twice: the first was to assess the past asbestos exposure and the second for different clinical reasons. Mineralogical analysis of BALF was carried out. RESULTS: In 16 patients (72.7%), a reduction of concentration in BALF of all asbestos fibres was observed. The concentrations of both chrysotile and amphiboles in the first bronchoalveolar lavage (BAL) were related to their concentrations in the second BAL and the observed differences were not statistically significant. A significant decrease in asbestos body concentration between the first and the second BAL was found (Wilcoxon test, P < 0.01). CONCLUSIONS: The reliability of the fibre concentration in BALF as a marker of past asbestos exposure seems quite good. In most cases, it allows us to distinguish workers in different classes of exposure and gives useful information on the pattern of exposure. Uncertainties related in general to lung residues and in particular to mineralogical analysis of BALF (mainly due to the high coefficient of variation (CV) at low fibre concentrations and the results of the statistical analysis on total fibres) suggest that this biomarker is more likely suitable for a qualitative/categorical approach to exposure assessment than a quantitative one.     

The usefulness of bronchoalveolar lavage in identifying past occupational exposure to asbestos: a light and electron microscopy study.

Fiberoptic bronchoscopy has permitted the development of lavage procedures for the collection of lung washes. In certain disease states this material may contain large numbers of phagocytic cells (macrophages and neutrophils). Since these phagocytes are the predominant "dust scavenger cells" in the lung, the assessment of their particulate burden as well as that of the overall lavage material has been suggested as a potentially important diagnostic tool. The studies to date have shown that the presence of ferruginous bodies is an indication of past occupational exposure. In the present study, a digestion procedure was carried out on bronchoalveolar lavage material collected from individuals who were occupationally exposed to asbestos and from samples obtained from the general population. The parameters used for distinguishing the source of these samples included both light microscopy assessment of the filters for the presence of ferruginous bodies and electron microscopic screening for the presence of uncoated fibers.