CT patterns of pleuro-pulmonary damage caused by inhalation of pumice as a model of pneumoconiosis from non-fibrous amorphous silicates

Our plain-English summary of CT patterns of pleuro-pulmonary damage caused by inhalation of pumice as a model of pneumoconiosis from non-fibrous amorphous silicates, by C. Costa, G. Ascenti, E. Scribano, et al (La Radiologia Medica, 2016).

The study

• Authors: C. Costa, G. Ascenti, E. Scribano, T. D'Angelo, M. Gaeta, C. Fenga, A. Blandino, S. Mazziotti
• Journal: La Radiologia Medica
• Published: 2016;121(1):19-26
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Purpose: The aim of this article is to correlate the radiological features of pleuro-pulmonary damage caused by inhalation of pumice (an extrusive volcanic rock classified as a non-fibrous, amorphous, complex silicate) with exposure conditions.

Materials And Methods: 36 subjects employed in the pumice quarries were evaluated for annual follow-up in a preventive medical surveillance program including spirometry, chest CT lasting from 1999 to 2014. They were only male subjects, mean age 56.92 ± 16.45 years. Subjects had worked in the quarries for an average of 25.03 ± 9.39 years. Domestic or occupational exposure to asbestos or other mineral dusts other than pumice was excluded. Subjects were also classified as smokers, former smokers and nonsmokers.

Results: Among the 36 workers examined, we identified four CT patterns which resulted to be dependent on exposure duration and intensity, FVC, FEV1 and FEF25-75, but not on cigarette smoking. The most common symptoms reported by clinical examination were dyspnoea, cough and asthenia. In no case it was proven an evolution of CT findings during follow-up for 10 years.

Conclusions: Liparitosis, caused by pumice inhalation, can be considered a representative example of pneumoconiosis derived by amorphous silica compounds, which are extremely widespread for industrial manufacturing as well as for applicative uses, such as nano-materials. Moreover, being pumice free of quartz contamination, it can represent a disease model for exposure to pure non-fibrous silicates.

In plain English

This study followed 36 male pumice quarry workers on Lipari, an island in Sicily, Italy. From June 1999 to November 2014 they had yearly clinical exams and breathing tests, plus yearly chest CT scans for the first 5 years, then monitoring after 5 years. Pumice is a volcanic rock of mostly amorphous, non-fibrous silica. No worker had a history of exposure to asbestos or to mineral dusts other than pumice. On CT, 22 of 36 workers showed no damage. Six had pleural plaques without lung involvement. Six had masses near the lung roots with calcifications, 2 also with pleural plaques. Two had clusters of small lung nodules with masses and pleural plaques. All affected workers had worked in the pre-technological period, before plant improvements in 1985. The groups differed significantly in years of exposure and lung function, but not in smoking. In no case was a change in CT findings shown during up to 10 years of follow-up. The authors concluded that CT findings correlated with duration and intensity of exposure. They noted the small study size as a limitation.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Medical surveillance series of exposed workers with yearly clinical examination and spirometry, chest CT yearly for the first 5 years and then monitoring after 5 years, plus laboratory analysis of pumice powder
• Who was studied: 36 male workers employed in the pumice quarries of Lipari (Aeolian Archipelago, Sicily, Italy), followed June 1999 to November 2014; mean age 56.92 years; average 25.03 years worked in the quarries
• Exposure: Occupational inhalation of pumice powder (a non-fibrous, amorphous silicate), assessed by job title, years worked in the quarry and latency of symptoms. No worker had a history of domestic or occupational exposure to asbestos or to mineral dusts other than pumice.
• Main results:
  • Pattern A (no damage on CT): 22 of 36 workers (61.11%)
  • Pattern B (pleural plaques without lung parenchymal involvement): 6 of 36 workers (16.67%)
  • Pattern C (perihilar masses with reticular calcifications without parenchymal involvement): 6 of 36 workers
  • Within pattern C, 2 workers also had pleural plaques
  • Pattern D (clusters of centrilobular nodules with interlobular septal thickening, always with perihilar masses and pleural plaques): 2 of 36 workers (5.55%)
  • In no case was a change in CT findings proven during up to 10 years of follow-up
  • All workers in groups B, C and D had worked in the pre-technological period
  • The authors treated 1985, the year of substantial plant improvements, as the border between the pre-technological and technological periods
  • Mean years of exposure differed significantly between groups A, B, C and D (19.0, 37.1, 34.3 and 32.2 years; p less than 0.001)
  • Mean FVC as percent of predicted was 88.5 in group A, 81.0 in group B, 62.2 in group C and 56.7 in group D (p less than 0.001)
  • Groups did not differ significantly in smoking
  • A significant Spearman correlation was found between CT pattern group and years of exposure
  • Electron microscopy showed pumice particles were often elongated but never fibrous
• The authors' conclusion: The authors concluded that, based on 10 years of follow-up, CT findings correlated with duration and intensity of exposure. They hypothesized that pumice lung disease (liparitosis) may be a model for disease from pure non-fibrous amorphous silicates, while stating that further studies are needed.
• Limitations the authors state:
  • No correlation was found between ILO chest X-ray classification and CT patterns
  • Small study population
  • Dust measurements were indoor averages without personal or task-specific sampling
  • No dust measurements were made in the pre-technological period

Topics

Medical terms in this study, explained in our Lexicon: Pneumoconiosis, Silicate, Spirometry, Occupational Exposure, FEV1.

Related studies

• Computed tomography features of liparitosis: a pneumoconiosis due to amorphous silica — S. Mazziotti, M. Gaeta, et al. (2004)
• Pulmonary disease caused by the inhalation of cosmetic talcum powder — I.P. Wells, P.A. Dubbins, et al. (1979)
• Rat lung reactivity to natural and man-made fibrous silicates following short-term exposure — I. Lemaire, P.G. Dionne, et al. (1989)
• Why pretend that "non-asbestos" fibrous silicates are not "asbestos"? — T.L. Guidotti (2013)
• Biopersistence of rock wool in lungs after short-term inhalation in rats — Y. Kudo, Y. Aizawa (2008)
• Chrysotile asbestos detoxification with a combined treatment of oxalic acid and silicates producing amorphous silica and biomaterial — A. Valouma, A. Verganelaki, et al. (2016)

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