Lung asbestos fiber burden analysis: effects of the counting rules for legal medicine evaluations.

OBJECTIVES: The work shows the effect of counting rules, such as analysis magnification and asbestos fiber dimension to be count (with length ≥5 µm or also asbestos fibers with length <5 µm) in the lung asbestos fiber burden analysis for legal medicine evaluations. METHODS: On the same lung tissue samples, two different analyses were carried out to count any asbestos fibers with length ≥1 µm and with length ≥5 µm. Results of the amphibole burden of the two analyses were compared by linear regression analysis on log10-transformed values. RESULTS: The analysis should be carried out at an appropriate magnification and on samples prepared in such a way as they allow the counting of very fine fibers. If the analysis is limited to the asbestos fibers with length ≥5 µm, there is a high risk of not detecting possible residual chrysotile fiber burden and thinner crocidolite asbestos fibers. CONCLUSIONS: On average we estimated that 1 amphibole fiber with length ≥5 µm corresponds to ∼8 amphibole fibers with length ≥1 µm in the lung. The values of the Helsinki criteria should be updated taking this into account.

Pleural mesothelioma in doll manufacture: possible asbestos exposure. / Mesoteliomi pleurici in addette alla fabbricazione di bambole: esposizione ad amianto?

BACKGROUND: The occurrence of malignant mesothelioma is almost always causally associated to asbestos exposure but, considering women occurrences, this association is often difficult to demonstrate and consequently the asbestos exposure is defined as 'unknown'. OBJECTIVES: To describe the working activity and to give occupational asbestos exposure probability estimation related to an uncommon and poorly investigated productive sector: doll manufacture. METHODS: From the Province of Brescia Mesothelioma Registry, established in 1993 on population-based criteria, we have extracted the certified mesothelioma diagnosis cases, related to patients who were employed for some time in doll manufacture. RESULTS: Among the 757 total cases of malignant mesothelioma registered and studied up to 2016, we found 3 cases of pleural epithelial mesothelioma histologically diagnosed in young women who had worked in two doll manufacturing companies and whose asbestos exposure had been initially defined as 'unknown', because an environmental, family or extra-professional asbestos exposure was considered unlikely. However, the judicial autopsy performed on one of the 3 women had allowed examining lung tissue samples with Scanning Electron Microscopy. This technique showed a concentration of amphiboles fibers of about 12,000,000 per gram of dry lung tissue, with a consequent re-classification of asbestos exposure from 'unknown' to 'occupational certified'. DISCUSSION: Mesotheliomas in women with no apparent occupational asbestos exposure are normally referred to life or family environmental exposure. Moreover, it is known that occupational asbestos exposure in women is difficult to recognize. Previously, only one publication had reported two cases of mesothelioma in cloth doll manufacture. The occurrence of two mesothelioma cases in the same company out of the three here presented was suggesting an occupational exposure. The finding of a high amphibole fibers lung concentration confirmed the previous hypothesis, despite the impossibility to determine the circumstances with good evidence. CONCLUSION: The three cases of mesothelioma in doll production workers suggest that also in this restricted manufacturing sector had occurred an occupational asbestos exposure, which is up to now unknown and isn't due only to the use of sewing or ironing machines. The lung asbestos fibers burden analysis is confirmed to be a decisive factor in the assessment of mesothelioma cases with 'unknown' exposure.

Lung fibre burden and risk of malignant mesothelioma in shipyard workers: a necropsy-based case-control study.

OBJECTIVES: In Italy, the highest pleural cancer mortality and incidence have been observed among Italian regions where the 2 largest Italian shipyards were (and are) located. The objective of this study was to assess the exposure-response relationship for mesothelioma among male workers employed in the Monfalcone, Italy, shipyard. METHODS: We conducted a necropsy-based case-control study. Cases (N = 102) were mesothelioma decedents and controls were those with lung cancer (N = 84). Complete job histories were available; the lung fibre content was measured using a scanning electron microscope with X-ray fluorescence, after sample preparation according to the European Respiratory Society guidelines. Odds ratios and 95% confidence intervals of mesothelioma by fibre type and lung fibre burden, as a categorical or continuous variable, were assessed by unconditional logistic regression, adjusted for age and time since exposure cessation. Analyses for the amphibole and chrysotile lung fibre burden were mutually adjusted. We calculated a cumulative exposure index by applying a job-exposure matrix to the job histories of study cases and assessed its correlation with the lung fibre burden. RESULTS: We found an odds ratio of 22.0 (confidence intervals 5.66-85.7) for the highest lung fibre burden category (mean 43.8 million total asbestos fibres per gram of dry tissue) compared with the reference (mean 0.48). Using log10-transformed lung fibre burden, we found that the odds ratio was 3.71 (confidence intervals 2.03-6.79) for a 10-fold lung fibre burden increase. Results for the amphibole lung fibre burden were similar. Odds ratios increased over chrysotile lung fibre burden categories (P-trend = 0.025), and the odds ratio for a 10-fold increase was 4.73 (confidence intervals 0.32-70.4). CONCLUSIONS: The cumulative exposure index was correlated with total and amphibole lung fibre burden, but not with chrysotile lung fibre burden. Mesothelioma risk was proportional to total, amphibole, and chrysotile lung fibre burden in shipyard workers.

Is Mesothelioma Unrelated to the Lung Asbestos Burden? Comment on Visonà et al. Inorganic Fiber Lung Burden in Subjects with Occupational and/or Anthropogenic Environmental Asbestos Exposure in Broni (Pavia, Northern Italy): An SEM-EDS Study on Autoptic Samples. Int. J. Environ. Res. Public Health 2021, 18, 2053.

We read with interest the report by Visonà and coworkers on the lung asbestos fiber burden in an autopsy series of decedents from mesothelioma (MM: 59 cases) and individuals who "suffered from asbestosis and died of its complications" (13 cases) [...].