Asbestos Lung Burden Research Articles

A postmortem case control study of asbestos burden in lungs of malignant mesothelioma cases

BackgroundAsbestos lung content is regarded as the most reliable tool for causal attribution of malignant mesothelioma (MM) to previous asbestos exposures. However, there is a lack of studies on asbestos burden in lungs of MM patients in comparison with healthy individuals. This study aims to provide such a comparison, investigating, as well, differences in asbestos lung burden with sex and time trends.MethodsAsbestos lung content has been assessed on formalin-fixed lung fragments using scanning electron microscopy coupled with energy dispersion spectroscopy (SEM–EDS) on individuals deceased from MM (cases) and healthy subjects without any lung disease who died from violent causes (controls) between 2005 and 2023.ResultsAsbestos and asbestos bodies (ABs) were found, respectively, in 73.7% and 43.2% of cases and in 28 and 22% of controls; in MM cases the most represented asbestos types were crocidolite and amosite, whereas in controls it was tremolite-actinolite asbestos. The concentration of both asbestos fibers and ABs was statistically significantly higher in MM cases compared to controls. The mean asbestos fibers width was also significantly higher in cases than controls. Males and females with MM showed similar asbestos and ABs concentrations, but females had higher concentrations of chrysotile, and significantly lower fibers width compared to males. Time trends show that MM lung asbestos concentrations decreased starting in 2011.DiscussionThe results suggest a correlation between asbestos burden in lungs and MM risk. The different concentration of chrysotile, as well as the different width of asbestos fibers in MM males and females might reflect a sex difference in response of the lung microenvironment to inhaled asbestos. Finally, this study provides the first pathological evidence of the effect of the ban of asbestos use, demonstrating a significant decrease of asbestos lung content after 2011.

Asbestos burden in lungs of non-occupationally exposed women from Broni (Pavia, Italy): a postmortem SEM-EDS study.

In Italy the incidence of malignant mesothelioma (MM) among women is remarkably high, due to the several contexts in which women had been exposed to asbestos. However, very few studies in literature focus on the inorganic lung content in women. The aim of this retrospective, observational study is to investigate the asbestos lung burden, in terms of concentration, dimensions and type of asbestos, in 42 women who died from MM and had been non-occupationally exposed to asbestos during the activity of the asbestos-cement plant located in Broni (Pavia, Northern Italy) where mainly chrysotile, crocidolite and amosite were used. Lung samples taken during forensic autopsies have been digested using sodium hypochlorite and filtered through a cellulose-ester membrane. The filter was examined using a scanning electron microscope and the chemical composition of the fibers was analyzed using an electron dispersive spectroscopy. The number of detected inorganic fibers, asbestos fibers and asbestos bodies (ABs) were normalized to 1 gram of dry tissue. In six samples no asbestos has been detected. Overall, the most represented kind of asbestos was amosite, followed by crocidolite, tremolite/actinolite asbestos and chrysotile. The concentration of all inorganic fibers was significantly higher in women with environmental and household exposures compared with those with only environmental exposure (P=0.025), as well as the concentration of asbestos fibers (P=0.019) and ABs (P=0.049). We found a significant correlation between the concentration of asbestos fibers and the duration of exposure (rho =0.413, P=0.008), as well as with the latency of MM (rho =0.427, P=0.005). The distance of the residential address from the factory and the time spent daily in contact with asbestos did not influence the lung asbestos burden. These results suggest the relevance of the lung clearance of asbestos, regarding mainly chrysotile. As a consequence, although scanning electron microscopy -energy dispersive X-ray spectroscopy (SEM-EDS) is considered the most reliable tool for assessing previous exposure to asbestos, its results should be interpreted with caution, especially in a legal context. In addition, our data confirm the relevance of environmental and household exposure in determining asbestos concentration in lungs and highlight the importance of household exposure.

Asbestos exposure, lung fiber burden, and mesothelioma rates: Mechanistic modelling for risk assessment

ContextRelationships among asbestos exposure, lung burden, and mesothelioma risks have been previously evaluated, but it would be useful to validate published epidemiological observations with a mathematical model describing deposition and elimination of various mineral types of fibers. Objective(a) To develop a mechanistical model demonstrating uptake and removal of fibers from human lungs, (b) To test the model on the results of a British case-control study, (c) To quantify the updated values for elimination coefficient of various mineral types of asbestos fibers. MethodsA mechanistic model utilizing the first-order kinetic relationship is proposed that relates levels of exposure to mineral fibers, elimination coefficients, and lung burden at certain points of time. The behaviour of the model was explored for different exposure scenarios. Elimination coefficients for various mineral types were estimated based on the observed proportion of asbestos minerals in exposure vs observed lung burden. ResultsBased on the proposed model, the average elimination coefficient was estimated for crocidolite as 0.099 vs average published value of 0.092, for amosite as 0.169 vs 0.19, and for chrysotile as 6.45 vs average published value of 6.36 (years−1). Lung burden level was demonstrated to change linearly with exposure intensity, and supra-linearly with exposure duration. The simulation of three separate exposure events during three decades showed that lung burden level prevailingly depends on the most recent event (R = 0.967, p < 0.05) and only weakly correlates with the most remote event (R = 0.032, p < 0.05). ConclusionIn spite of potential limitations, mechanistical modelling of asbestos exposure can serve as an effective tool for risk assessment purposes.

Asbestos Lung Burden Does Not Predict Survival in Malignant Pleural Mesothelioma: A Necropsy-Based Study of 185 Cases

IntroductionMalignant pleural mesothelioma is an asbestos-related disease with poor survival. The prognostic role of histologic subtype is well established. Some studies (without a biological hypothesis) suggested that higher asbestos lung burden is associated with reduced survival. MethodsWe selected subjects from two series of necropsies: residents in Brescia province (North-West Italy) and workers (or persons living with them) employed in the Monfalcone shipyards (North-East Italy). Asbestos fibers and asbestos bodies in lung samples were counted using a scanning electron and an optical microscope, respectively. Separately in the two series, we analyzed median survival time and fitted multivariable Cox regression models (adjusted for sex, period and age at diagnosis, and histopatholocical diagnosis) to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for three levels of asbestos fiber counts (reference: <1 million fibers/g of dry lung tissue). ResultsWe analyzed 185 necropsies, 83 in Brescia and 102 in Monfalcone. Despite a much higher lung burden in Monfalcone patients, median survival was slightly shorter in Brescia (8.3 mo) than in Monfalcone (10.2 mo). In Brescia, medium (1.0–9.9) and high (10+) fiber burden HRs were 0.91 (95% CI: 0.54–1.53) and 1.23 (95% CI: 0.41–3.70), respectively. In Monfalcone, the corresponding HRs were 1.18 (95% CI: 0.59–2.35) and 1.63 (95% CI: 0.77–3.45), respectively. ConclusionsNo relationship between asbestos lung burden and survival was found. Histologic subtype was the strongest prognostic determinant.

Pleural mesothelioma and lung cancer risks in relation to occupational history and asbestos lung burden

BackgroundWe have conducted a population-based study of pleural mesothelioma patients with occupational histories and measured asbestos lung burdens in occupationally exposed workers and in the general population. The relationship between...

Asbestos Lung Burden in Necroscopic Samples from the General Population of Milan, Italy.

The present study analysed the asbestos lung burden in necroscopic samples from 55 subjects free from asbestos-related diseases, collected between 2009 and 2011 in Milan, Italy. Multiple lung samples were analysed by light microscopy (asbestos bodies, AB) and EDXA-scanning electron microscopy (asbestos fibres and other inorganic fibres). Asbestos fibres were detected in 35 (63.6%) subjects, with a higher frequency for amphiboles than for chrysotile. Commercial (CA) and non-commercial amphiboles (NCA) were found in roughly similar frequencies. The estimated median value was 0.11 million fibres per gram of dry lung tissue (mf g(-1)) for all asbestos, 0.09 mf g(-1) for amphiboles. In 44 (80.0%) subjects no chrysotile fibres were detected. A negative relationship between asbestos mass-weighted fibre count and year of birth (and a corresponding positive increase with age) was observed for amphiboles [-4.15%, 95% confidence interval (CI) = -5.89 to -2.37], talc (-2.12%, 95% CI = -3.94 to -0.28), and Ti-rich fibres (-3.10%, 95% CI = -5.54 to -0.60), but not for chrysotile (-2.84%, 95% CI = -7.69 to 2.27). Residential district, birthplace, and smoking habit did not affect the lung burden of asbestos or inorganic fibres. Females showed higher burden only for amphiboles (0.12 versus 0.03 mf g(-1) in males, P = 0.07) and talc fibres (0.14 versus 0 mf g(-1) in males, P = 0.03). Chrysotile fibres were shorter and thinner than amphibole fibres and NCA fibres were thicker than CA ones. The AB prevalence was 16.4% (nine subjects) with concentrations ranging from 10 to 110 AB g(-1) dry, well below the 1000 AB g(-1) threshold for establishing occupational exposure. No AB were found in subjects younger than 30 years. Our study demonstrated detectable levels of asbestos fibres in a sample taken from the general population. The significant increase with age confirmed that amphibole fibres are the most representative of cumulative exposure.

Cumulative Retrospective Exposure Assessment (REA) as a predictor of amphibole asbestos lung burden: validation procedures and results for industrial hygiene and pathology estimates

Context: A detailed evaluation of the correlation and linearity of industrial hygiene retrospective exposure assessment (REA) for cumulative asbestos exposure with asbestos lung burden analysis (LBA) has not been previously performed, but both methods are utilized for case-control and cohort studies and other applications such as setting occupational exposure limits.Objective: (a) To correlate REA with asbestos LBA for a large number of cases from varied industries and exposure scenarios; (b) to evaluate the linearity, precision, and applicability of both industrial hygiene exposure reconstruction and LBA; and (c) to demonstrate validation methods for REA.Methods: A panel of four experienced industrial hygiene raters independently estimated the cumulative asbestos exposure for 363 cases with limited exposure details in which asbestos LBA had been independently determined. LBA for asbestos bodies was performed by a pathologist by both light microscopy and scanning electron microscopy (SEM) and free asbestos fibers by SEM. Precision, reliability, correlation and linearity were evaluated via intraclass correlation, regression analysis and analysis of covariance. Plaintiff’s answers to interrogatories, work history sheets, work summaries or plaintiff’s discovery depositions that were obtained in court cases involving asbestos were utilized by the pathologist to provide a summarized brief asbestos exposure and work history for each of the 363 cases.Results: Linear relationships between REA and LBA were found when adjustment was made for asbestos fiber-type exposure differences. Significant correlation between REA and LBA was found with amphibole asbestos lung burden and mixed fiber-types, but not with chrysotile. The intraclass correlation coefficients (ICC) for the precision of the industrial hygiene rater cumulative asbestos exposure estimates and the precision of repeated laboratory analysis were found to be in the excellent range. The ICC estimates were performed independent of specific asbestos fiber-type.Conclusions: Both REA and pathology assessment are reliable and complementary predictive methods to characterize asbestos exposures. Correlation analysis between the two methods effectively validates both REA methodology and LBA procedures within the determined precision, particularly for cumulative amphibole asbestos exposures since chrysotile fibers, for the most part, are not retained in the lung for an extended period of time.

The analysis of asbestos count data with “nondetects”: The example of asbestos fiber concentrations in the lungs of brake workers

In the analysis of tissue for asbestos fibers, some measurements may be below the analytical detection limit (nondetects). The use of maximum likelihood and survival analysis methods have been recommended to perform comparisons between subjects in the presence of nondetects. When the data consist of "counts" another method is useful. This method is discussed, and illustrated with an analysis of asbestos lung burden data among brake mechanics previously analyzed by other methods. Statistical models for count data, namely Poisson and negative binomial regression, were used to compare the asbestos fiber concentrations in the lungs of brake mechanics with those of control subjects. The fit of the models was assessed with an analysis of residuals. The negative binomial regression models fit the data well. The concentrations of Quebec asbestos fibers in the lungs of the brake mechanics were significantly higher than in the control population. Helsel recommended the use of maximum likelihood and survival analysis methods to perform comparisons in the presence of nondetects. When analyzing asbestos fiber count data, or other count data arising in occupational or environmental health, the use of models such as the Poisson and negative binomial may be added to the analyst's toolbox. Benefits are that neither of these methods requires the substitution of arbitrary values for the nondetects and that programs for the computation of count data models are contained in popular statistical software packages.

63 Asbestos lung burden and mesothelioma risk due to past and current occupational and environmental exposure conditions in Great Britain

ObjectivesTo characterise the relationship between mesothelioma risk and asbestos lung burden inGreat Britain. To identify the asbestos lung burdens due to current or recent occupational and environmental asbestos exposures, and...

Modelling mesothelioma mortality in Great Britain using the two-stage clonal expansion model

ObjectivesAsbestos is a carcinogen that is the cause of the majority of mesothelioma cases worldwide. Various models have been used to describe the increase and likely future pattern of mesothelioma...

Fallbericht zu einer seltenen Berufskrankheit: Eine zu Lebzeiten nicht anerkannte Talkose

Talc is a hydrated magnesium silicate used in the chemical, ceramic, cosmetic, leather, paper and building industries. Interstitial lung disease - talcosis - due to exclusive talc inhalation is a rare form of pneumoconiosis. More often, pulmonary disease due to talc is encountered after intravenous administration of talc during drug abuse. Talc can contain asbestos or quartz particles which induce asbestosis or silicosis. Here we present a case report about a worker who was exposed to talcum during his work in tire manufacturing. During his lifetime an occupational disease was not recognised. The deceased had been forwarded to cremation; the legally prescribed second inspection of the corpse induced the suspicion of an occupational disease and an autopsy was ordered. The autopsy revealed a lung fibrosis with honeycomb lung alterations and under polarised light a massive burden with birefringed crystalline particles could be visualised. Light and electron microscopic lung dust analyses could exclude an elevated asbestos lung burden. The element analysis of foreign body material in lung tissue confirmed its chemical composition of magnesium and silicon which was consistent with talc. Based on the pathological and mineralogical findings, the confirmed occupational exposure towards talc and, due to the exclusion of other possible causes (asbestos, quartz), the diagnose of a talc-induced interstitial lung fibrosis - talcosis - was established. This case emphasises the importance of pathological-anatomic examinations in combination with lung dust analysis to reveal occupational exposure as a cause of an interstitial lung disease.

Asbestos lung burden and asbestosis after occupational and environmental exposure in an asbestos cement manufacturing area: a necropsy study.

OBJECTIVE: The largest Italian asbestos cement factory had been active in Casale Monferrato until 1986: in previous studies a substantial increase in the incidence of pleural mesothelioma was found among...

Biopersistence of respirable synthetic fibers and minerals: the point of view of the epidemiologist.

Biopersistence of fibers and minerals in human respiratory tissues is an important aspect of the toxicity of these agents. However, few data are available from human studies. Although a number of studies have measured the lung burden of asbestos and other minerals in exposed humans, few presented information relevant to biopersistence of these agents. The studies analyzing asbestos lung burden in workers at different intervals following cessation of exposure suggest a linear decrease in concentration over time, that is independent of duration of exposure. However, the available evidence on asbestos is too sparse to allow a firm conclusion; almost no data are available on other minerals.

Features of asbestos-exposed and unexposed mesothelioma.

Thirty-six histologically confirmed cases of pleural and peritoneal mesothelioma have been observed in a chest unit over a period of 53 months. The past asbestos exposure was assessed by a standardized questionnaire in all cases and the asbestos lung burden was determined by means of mineralogical analysis of lung-related biological specimens (sputum, bronchoalveolar lavage fluid, lung tissues) in 28 cases. The results of these two methods were found in good agreement. Past asbestos exposure has been definitely implicated in 17 cases and definitely eliminated in 10 cases. The results were inconclusive in other cases. The group with definite past asbestos exposure was different from the nonasbestos-exposed group by clinical, biological, pathological, and prognosis features that were analyzed. In cases without past asbestos exposure there were no other possible causative agents. Younger age and similar incidence in men and women suggest an environmental or natural disease.