The impact of coal mine dust characteristics on pathways to respiratory harm: investigating the pneumoconiotic potency of coals

Our plain-English summary of The impact of coal mine dust characteristics on pathways to respiratory harm: investigating the pneumoconiotic potency of coals, by C. Kamanzi, M. Becker, M. Jacobs, et al (Environmental Geochemistry and Health, 2023).

The study

• Authors: C. Kamanzi, M. Becker, M. Jacobs, P. Konečný, J. Von Holdt, J. Broadhurst
• Journal: Environmental Geochemistry and Health
• Published: 2023;45(10):7363-7388
• Type of article: Review
• Cited by: 27 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Exposure to dust from the mining environment has historically resulted in epidemic levels of mortality and morbidity from pneumoconiotic diseases such as silicosis, coal workers' pneumoconiosis (CWP), and asbestosis. Studies have shown that CWP remains a critical issue at collieries across the globe, with some countries facing resurgent patterns of the disease and additional pathologies from long-term exposure. Compliance measures to reduce dust exposure rely primarily on the assumption that all "fine" particles are equally toxic irrespective of source or chemical composition. For several ore types, but more specifically coal, such an assumption is not practical due to the complex and highly variable nature of the material. Additionally, several studies have identified possible mechanisms of pathogenesis from the minerals and deleterious metals in coal. The purpose of this review was to provide a reassessment of the perspectives and strategies used to evaluate the pneumoconiotic potency of coal mine dust. Emphasis is on the physicochemical characteristics of coal mine dust such as mineralogy/mineral chemistry, particle shape, size, specific surface area, and free surface area-all of which have been highlighted as contributing factors to the expression of pro-inflammatory responses in the lung. The review also highlights the potential opportunity for more holistic risk characterisation strategies for coal mine dust, which consider the mineralogical and physicochemical aspects of the dust as variables relevant to the current proposed mechanisms for CWP pathogenesis.

© 2023. The Author(s).

In plain English

This article was a review of published research on coal mine dust and coal workers' pneumoconiosis (CWP). Asbestosis was mentioned only in passing as another dust-caused disease, and the article did not study asbestos. The authors reviewed earlier work on how features of coal mine dust, including its minerals, particle size, shape and surface area, may relate to lung inflammation and disease. They described how CWP prevalence in the USA was rising, particularly in Appalachia, even after dust limits were lowered. Earlier studies they reviewed found that dust makeup varied between mines and mining activities, and that the amount of quartz may not consistently predict damage or CWP. One earlier study (Huang et al., 2005) reported a correlation of 0.94 (95% confidence interval 0.66 to 0.999) between bioavailable iron from pyrite and CWP prevalence. The review noted that this study said its correlations did not necessarily show causation. The authors concluded that it remains unclear which coal dust characteristics should be considered. They also concluded that studies have largely overlooked particle surface area and shape.

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: Review of published literature (review paper)
• Who was studied: No new participants or samples. The review covered published studies on coal mine dust, its characteristics and coal workers' pneumoconiosis, including historical, epidemiological, laboratory and animal studies.
• Exposure: Coal mine dust and its physical and chemical characteristics: mineral content (quartz, pyrite, bioavailable iron, clays such as kaolinite, siderite), carbonaceous matter, particle size, shape, specific surface area and surface reactivity. No asbestos fibers were studied.
• Main results:
  • The review described that, despite dust concentration limits at US collieries being reduced to 1.5 mg/m3 in 2014, CWP prevalence in the USA was increasing, particularly in Appalachia (citing Blackley et al., 2018).
  • Earlier studies reviewed found that the mineral makeup and particle sizes of coal mine dust varied between mines and between mining operations. The authors described this as showing that coal mine dust is heterogeneous.
  • The authors argued that the abundance of quartz in coal mine dust may not consistently predict oxidative damage or CWP prevalence, partly because quartz surfaces can be coated with clays.
  • The review reported an earlier study (Huang et al., 2005). That study used coal data from twenty-four mines across seven US states and CWP prevalence from a national survey. It found a correlation of 0.94 (95% confidence interval 0.66 to 0.999, P value 0.0015) between bioavailable iron (BAI) and CWP prevalence. The review noted that the earlier study highlighted that these correlations did not necessarily represent causation.
  • The authors wrote that experimental studies to date indicate that the carbonaceous (organic) matter in coal may not play a causative role in how harmful coal mine dust is to the lungs.
  • The authors found that mechanistic studies linking coal mine dust characteristics to cell damage and inflammation have mainly used composition data. These studies have neglected particle surface area, reactivity and shape.
• The authors' conclusion: The authors concluded that little consensus has been reached on which coal characteristics are responsible for disease, so it remains unclear which factors should be used to assess the pneumoconiotic potency of coals. They suggested that research systematically defining the relative contribution of the physical, chemical and mineral aspects of coal particles could help represent that potency, and that screening methods for these parameters could help develop targeted mitigation strategies.

Topics

Medical terms in this study, explained in our Lexicon: Silicosis, Pneumoconiosis, Mineralogy.

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