Evaluation of Deposition and Clearance of Asbestos (Detected by SEM-EDS) in Lungs of Deceased Subjects Environmentally and/or Occupationally Exposed in Broni (Pavia, Northern Italy).

Silvia D Visonà,Simona Villani,Paola Borrelli,Silvana Capella,Claudio Colosio,Sofia Bodini,Elena Belluso,Eleonora Crespi,Carlo Previderè

doi:10.3389/fpubh.2021.678040

Abstract

Biodurability is one of the main determinants of asbestos hazardousness for human health. Very little is known about the actual persistence of asbestos in lungs and its clearance, nor about differences in this regard between the different mineralogical types of asbestos. The aim of the present study was to evaluate the amount, the dimensional characteristics and the mineralogic kinds of asbestos in lungs (measured using SEM-EDS) of a series of 72 deceased subjects who were certainly exposed to asbestos (mainly crocidolite and chrysotile) during their life. Moreover, we investigated possible correlations between the lung burden of asbestos (in general and considering each asbestos type), as well as their dimension (length, width, and l/w ratio) and the duration of exposure, the latency- in case of malignant mesothelioma (MM), the survival and the time since the end of exposure. In 62.5% of subjects, asbestos burden in lungs was lower that the threshold considered demonstrative for occupational exposure. In 29.1% of cases no asbestos was found. Chrysotile was practically not detected. The mean length of asbestos fibers and the length to width ratio were significantly related to the duration of exposure to asbestos. No other statistically significant correlations were found between the amount and dimensional characteristics of asbestos (nor with the relative amount of each asbestos type) and the other chronological variables considered. In conclusion, it was pointed out that chrysotile can be completely removed from human lungs in <8 years and, instead, amphiboles persist much more time. The present results suggest, as well, that the finding of no asbestos in lungs cannot rule out the attribution of MM to asbestos (in particular, chrysotile) inhaled in an occupational setting. This point is of crucial importance from a legal point of view.

Highlights

The relation between exposure to asbestos and malignant mesothelioma (MM) is well-documented, but many issues concerning the etiopathogenesis of this disease, as well as of other asbestos-related diseases (ARD), are still debated
On the basis of lung content analysis, other authors suggested that the dose of chrysotile required to cause MM is higher than the dose of amphiboles [10]
Among the 45 subjects above mentioned, 24 lived nearby the industry; one of them was a safety inspector, who used to spend about 1 week per year at the plant; 12 of them were employed at the asbestos-cement plant as workmen; one of them was a surveyor who worked at the plant for 5 years; 2 worked at the railway station located inside the plant; the remaining five worked in other industries where asbestos was used in several ways

Summary

Introduction

The relation between exposure to asbestos and malignant mesothelioma (MM) is well-documented, but many issues concerning the etiopathogenesis of this disease, as well as of other asbestos-related diseases (ARD), are still debated. The relation between the duration of exposure and, on the other hand, the time between the end of exposure and death, on lung fiber burden in subjects died from MM, is still not fully understood. On the basis of lung content analysis (performed using analytical transmission electron microscopy), other authors suggested that the dose of chrysotile required to cause MM is higher than the dose of amphiboles [10]. They hypothesized that amphiboles are more potent carcinogens compared to chrysotile (in relation with its quicker degradation). Tremolite, that can be found in certain types of rocks that are mined to extract chrysotile, has been indicated as the real cause of chrysotile-induce mesothelioma [11]

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