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Rupani MP, Balachandar R, Kharkwal G, Kulkarni NP, Modi BV, Asodia RN, Vaghela KK, Nimavat DR. Mixed methods study on latent tuberculosis among agate stone workers and advocacy for testing silica dust exposed individuals in India. Sci Rep 2024; 14:13830. [PMID: 38879714 PMCID: PMC11180111 DOI: 10.1038/s41598-024-64837-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Accepted: 06/13/2024] [Indexed: 06/19/2024] Open
Abstract
The 2021 tuberculosis (TB) preventive treatment guidelines in India included silicosis as a screening group, yet latent TB infection (LTBI) testing for silica-dust-exposed individuals is underemphasized. Focusing on an estimated 52 million silica-dust-exposed workers, particularly agate-stone workers in Khambhat, Gujarat, our study aims to estimate LTBI prevalence, identify predictors, and gather insights from TB and silicosis experts. Employing a sequential explanatory mixed-methods approach, a cross-sectional study involved 463 agate-stone workers aged ≥ 20 years in Khambhat, using IGRA kits for LTBI testing. In-depth interviews with experts complemented quantitative findings. Among agate-stone workers, 58% tested positive for LTBI, with predictors including longer exposure, type of work, and BCG vaccination. Our findings reveal a nearly double burden of LTBI compared to the general population, particularly in occupations with higher silica dust exposure. Experts advocate for including silica-dust-exposed individuals in high-risk groups for LTBI testing, exploring cost-effective alternatives like improved skin sensitivity tests, and shorter TB preventive treatment regimens to enhance compliance. Future research should explore upfront TB preventive treatment for silica-dust-exposed individuals with high LTBI prevalence and optimal exposure duration. This study underscores the urgent need for policy changes and innovative approaches to TB prevention among silica-dust-exposed populations, impacting global occupational health strategies.
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Affiliation(s)
- Mihir P Rupani
- Division of Health Sciences, ICMR - National Institute of Occupational Health (NIOH), Indian Council of Medical Research (ICMR), Meghaninagar, Ahmedabad, Gujarat, 380016, India.
| | - Rakesh Balachandar
- Division of Health Sciences, ICMR - National Institute of Occupational Health (NIOH), Indian Council of Medical Research (ICMR), Meghaninagar, Ahmedabad, Gujarat, 380016, India
| | - Gitika Kharkwal
- Division of Biological Sciences, ICMR - National Institute of Occupational Health (NIOH), Indian Council of Medical Research (ICMR), Meghaninagar, Ahmedabad, Gujarat, 380016, India
| | - Nikhil P Kulkarni
- Division of Chemical Sciences, ICMR - National Institute of Occupational Health (NIOH), Indian Council of Medical Research (ICMR), Meghaninagar, Ahmedabad, Gujarat, 380016, India
| | - Bhavesh V Modi
- Department of Community and Family Medicine, All India Institute of Medical Sciences (AIIMS), Rajkot, Gujarat, 360006, India
| | - Rutu N Asodia
- Division of Health Sciences, ICMR - National Institute of Occupational Health (NIOH), Indian Council of Medical Research (ICMR), Meghaninagar, Ahmedabad, Gujarat, 380016, India
| | - Krishna K Vaghela
- Division of Health Sciences, ICMR - National Institute of Occupational Health (NIOH), Indian Council of Medical Research (ICMR), Meghaninagar, Ahmedabad, Gujarat, 380016, India
| | - Deizy R Nimavat
- Division of Health Sciences, ICMR - National Institute of Occupational Health (NIOH), Indian Council of Medical Research (ICMR), Meghaninagar, Ahmedabad, Gujarat, 380016, India
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Tankwanchi AS, Asabor EN, Vermund SH. Global Health Perspectives on Race in Research: Neocolonial Extraction and Local Marginalization. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:6210. [PMID: 37444057 PMCID: PMC10341112 DOI: 10.3390/ijerph20136210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 06/17/2023] [Accepted: 06/21/2023] [Indexed: 07/15/2023]
Abstract
Best practices in global health training prioritize leadership and engagement from investigators from low- and middle-income countries (LMICs), along with conscientious community consultation and research that benefits local participants and autochthonous communities. However, well into the 20th century, international research and clinical care remain rife with paternalism, extractive practices, and racist ideation, with race presumed to explain vulnerability or protection from various diseases, despite scientific evidence for far more precise mechanisms for infectious disease. We highlight experiences in global research on health and illness among indigenous populations in LMICs, seeking to clarify what is both scientifically essential and ethically desirable in research with human subjects; we apply a critical view towards race and racism as historically distorting elements that must be acknowledged and overcome.
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Affiliation(s)
- Akhenaten Siankam Tankwanchi
- Department of Health Systems and Population Health, University of Washington School of Public Health, Seattle, WA 98195, USA
| | - Emmanuella N. Asabor
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT 06510, USA; (E.N.A.); (S.H.V.)
| | - Sten H. Vermund
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT 06510, USA; (E.N.A.); (S.H.V.)
- Department of Pediatrics, Yale School of Medicine, New Haven, CT 06510, USA
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Smith JP, Oeltmann JE, Hill AN, Tobias JL, Boyd R, Click ES, Finlay A, Mondongo C, Zetola NM, Moonan PK. Characterizing tuberculosis transmission dynamics in high-burden urban and rural settings. Sci Rep 2022; 12:6780. [PMID: 35474076 PMCID: PMC9042872 DOI: 10.1038/s41598-022-10488-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 04/06/2022] [Indexed: 12/23/2022] Open
Abstract
Mycobacterium tuberculosis transmission dynamics in high-burden settings are poorly understood. Growing evidence suggests transmission may be characterized by extensive individual heterogeneity in secondary cases (i.e., superspreading), yet the degree and influence of such heterogeneity is largely unknown and unmeasured in high burden-settings. We conducted a prospective, population-based molecular epidemiology study of TB transmission in both an urban and rural setting of Botswana, one of the highest TB burden countries in the world. We used these empirical data to fit two mathematical models (urban and rural) that jointly quantified both the effective reproductive number, [Formula: see text], and the propensity for superspreading in each population. We found both urban and rural populations were characterized by a high degree of individual heterogeneity, however such heterogeneity disproportionately impacted the rural population: 99% of secondary transmission was attributed to only 19% of infectious cases in the rural population compared to 60% in the urban population and the median number of incident cases until the first outbreak of 30 cases was only 32 for the rural model compared to 791 in the urban model. These findings suggest individual heterogeneity plays a critical role shaping local TB epidemiology within subpopulations.
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Affiliation(s)
- Jonathan P Smith
- Department of Health Policy and Management, Yale School of Public Health, 60 College Street, New Haven, CT, 06510, USA.
- Peraton, 2800 Century Pkwy NE, Atlanta, GA, USA.
| | - John E Oeltmann
- Division of Global HIV and Tuberculosis, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Andrew N Hill
- Division of Tuberculosis Elimination, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | | | - Rosanna Boyd
- Division of Tuberculosis Elimination, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Eleanor S Click
- Division of Global HIV and Tuberculosis, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Alyssa Finlay
- Division of Global HIV and Tuberculosis, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Chawangwa Mondongo
- Botswana-UPenn Partnership, University of Pennsylvania, Philadelphia, USA
| | - Nicola M Zetola
- Botswana-UPenn Partnership, University of Pennsylvania, Philadelphia, USA
| | - Patrick K Moonan
- Division of Global HIV and Tuberculosis, Centers for Disease Control and Prevention, Atlanta, GA, USA
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Williams H, Ehrlich R, Barker S, Kisting-Cairncross S, Zungu M, Yassi A. The Utility of Length of Mining Service and Latency in Predicting Silicosis among Claimants to a Compensation Trust. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19063562. [PMID: 35329249 PMCID: PMC8953429 DOI: 10.3390/ijerph19063562] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 03/10/2022] [Accepted: 03/11/2022] [Indexed: 02/01/2023]
Abstract
In the wake of a large burden of silicosis and tuberculosis among ex-miners from the South African gold mining industry, several programmes have been engaged in examining and compensating those at risk of these diseases. Availability of a database from one such programme, the Q(h)ubeka Trust, provided an opportunity to examine the accuracy of length of service in predicting compensable silicosis, and the concordance between self-reported employment and that officially recorded. Compensable silicosis was determined by expert panels, with ILO profusion ≥1/0 as the threshold for compensability. Age, officially recorded and self-reported years of service, and years since first and last service of 3146 claimants for compensable silicosis were analysed. Self-reported and recorded service were moderately correlated (R = 0.66, 95% confidence interval 0.64−0.68), with a Bland−Altman plot showing no systematic bias. There was reasonably high agreement with 75% of the differences being less than two years. Logistic regression and receiver operating characteristic curve analysis were used to test prediction of compensable silicosis. There was little predictive difference between length of service on its own and a model adjusting for length of service, age, and years since last exposure. Predictive accuracy was moderate, with significant potential misclassification. Twenty percent of claimants with compensable silicosis had a length of service <10 years; in almost all these claims, the interval between last exposure and the claim was 10 years or more. In conclusion, self-reported service length in the absence of an official service record could be accepted in claims with compatible clinical findings. Length of service offers, at best, moderate predictive capability for silicosis. Relatively short service compensable silicosis, when combined with at least 10 years since last exposure, was not uncommon.
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Affiliation(s)
- Haidee Williams
- Division of Occupational Medicine, School of Public Health and Family Medicine, University of Cape Town, Cape Town 7925, South Africa; (R.E.); (S.K.-C.)
- Correspondence:
| | - Rodney Ehrlich
- Division of Occupational Medicine, School of Public Health and Family Medicine, University of Cape Town, Cape Town 7925, South Africa; (R.E.); (S.K.-C.)
| | - Stephen Barker
- School of Population and Public Health, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; (S.B.); (A.Y.)
| | - Sophia Kisting-Cairncross
- Division of Occupational Medicine, School of Public Health and Family Medicine, University of Cape Town, Cape Town 7925, South Africa; (R.E.); (S.K.-C.)
| | - Muzimkhulu Zungu
- School of Health Systems and Public Health, University of Pretoria, Pretoria 0002, South Africa;
- National Institute for Occupational Health, Division of the National Health Laboratory Service, Johannesburg 2000, South Africa
| | - Annalee Yassi
- School of Population and Public Health, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; (S.B.); (A.Y.)
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Access of migrant gold miners to compensation for occupational lung disease: Quantifying a legacy of injustice. J Migr Health 2021; 4:100065. [PMID: 34729543 PMCID: PMC8546409 DOI: 10.1016/j.jmh.2021.100065] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 09/28/2021] [Accepted: 10/04/2021] [Indexed: 11/24/2022] Open
Abstract
Background A legacy of the South African gold mining industry, now in decline, is a large burden of silicosis and tuberculosis among former migrant miners from rural South Africa and surrounding countries, particularly Lesotho and Mozambique. This neglected population faces significant barriers in filing claims for compensation for occupational lung disease. The objective of the study was to gain insight into the extent of such barriers, particularly for former miners and cross-border migrants. Methods The database of a large gold mining company and the statutory compensation authority were analyzed for the period 1973–2018 by country of origin, age, and employment status at the time of claim filing. Proportions and odds ratios (ORs) for each of the compensable diseases were calculated by the above variables. Processing delays of claims were also calculated. Results Annual company employment declined from 240,718 in 1989 to 43,024 in 2018 and the proportion of cross-border migrants within the workforce from 51.0 to 28.1%. The compensation database contained 68,612 claims. The majority of compensable claims in all diagnostic categories were from active miners. The odds of cross-border miners relative to South African miners filing a claim depended on employment status. For example, the OR for Lesotho miners filing while in active employment was 1.86 (95% CI 1.81, 1.91), falling to 0.94 (95% CI 0.91, 0.98) among former miners. The equivalent findings for Mozambiquan miners were 0.95 (95% CI 0.91, 1.00), falling to 0.44 (95% CI 0.41, 0.47). Median processing delays over the whole period were from 1.1 years from filing to adjudication, and 3.8 years from filing to payment. Conclusions The findings provide a quantitative view of differential access to occupational lung disease compensation, including long processing delays, among groups of migrant miners from the South African gold mines. There is a deficit of compensable claims for silicosis and silico-tuberculosis among former miners irrespective of country of origin. While cross-border miner groups appear to file more claims while active, this is reversed once they leave employment. Current large-scale efforts to provide medical examinations and compensation justice to this migrant miner population need political and public support and scrutiny of progress.
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Chang M, Xu G, Xiong C, Yang X, Yan S, Tao Y, Li H, Li Y, Yao S, Zhao Y. Alpha-lipoic acid attenuates silica-induced pulmonary fibrosis by improving mitochondrial function via AMPK/PGC1α pathway activation in C57BL/6J mice. Toxicol Lett 2021; 350:121-132. [PMID: 34252510 DOI: 10.1016/j.toxlet.2021.07.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 05/22/2021] [Accepted: 07/07/2021] [Indexed: 11/17/2022]
Abstract
Silicosis is characterized by pulmonary interstitial fibrosis that arises as a result of chronic exposure to silica. The few available treatments only delay its progression. As α-lipoic acid (ALA) has been shown to have various beneficial effects, including mitoprotective, antioxidant, and anti-inflammatory effects, we hypothesized that it may exhibit therapeutic effects in pulmonary fibrosis. Therefore, in the present study, we used a murine model of silicosis to investigate whether supplementation with exogenous ALA could attenuate silica-induced pulmonary fibrosis by improving mitochondrial function. ALA was administered to the model mice via continuous intragastric administration for 28 days, and then the antioxidant and mitoprotective effects of ALA were evaluated. The results showed that ALA decreased the production of reactive oxygen species, protected mitochondria from silica-induced dysfunction, and inhibited extracellular matrix deposition. ALA also decreased hyperglycemia and hyperlipidemia. Activation of the mitochondrial AMPK/PGC1α pathway might be responsible for these ALA-mediated anti-fibrotic effects. Exogenous ALA blocked oxidative stress by activating NRF2. Taken together, these findings demonstrate that exogenous ALA effectively prevents the progression of silicosis in a murine model, likely by stimulating mitochondrial biogenesis and endogenous antioxidant responses. Therefore, ALA can potentially delay the progression of silica-induced pulmonary fibrosis.
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Affiliation(s)
- Meiyu Chang
- School of Public Health, Xinxiang Medical University, Xinxiang, Henan Province, 453003, PR China
| | - Guangcui Xu
- School of Public Health, Xinxiang Medical University, Xinxiang, Henan Province, 453003, PR China
| | - Cheng Xiong
- School of Public Health, Xinxiang Medical University, Xinxiang, Henan Province, 453003, PR China
| | - Xuesi Yang
- School of Public Health, Xinxiang Medical University, Xinxiang, Henan Province, 453003, PR China
| | - Sensen Yan
- School of Public Health, Xinxiang Medical University, Xinxiang, Henan Province, 453003, PR China
| | - Yingjun Tao
- School of Public Health, Xinxiang Medical University, Xinxiang, Henan Province, 453003, PR China
| | - Haibin Li
- School of Public Health, Xinxiang Medical University, Xinxiang, Henan Province, 453003, PR China
| | - Yuchun Li
- School of Public Health, Xinxiang Medical University, Xinxiang, Henan Province, 453003, PR China
| | - Sanqiao Yao
- School of Public Health, Xinxiang Medical University, Xinxiang, Henan Province, 453003, PR China
| | - Yingzheng Zhao
- School of Public Health, Xinxiang Medical University, Xinxiang, Henan Province, 453003, PR China.
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Spiegel JM, Ehrlich R, Yassi A, Riera F, Wilkinson J, Lockhart K, Barker S, Kistnasamy B. Using Artificial Intelligence for High-Volume Identification of Silicosis and Tuberculosis: A Bio-Ethics Approach. Ann Glob Health 2021; 87:58. [PMID: 34249620 PMCID: PMC8252970 DOI: 10.5334/aogh.3206] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Although Artificial Intelligence (AI) is being increasingly applied, considerable distrust about introducing "disruptive" technologies persists. Intrinsic and contextual factors influencing where and how such innovations are introduced therefore require careful scrutiny to ensure that health equity is promoted. To illustrate one such critical approach, we describe and appraise an AI application - the development of computer assisted diagnosis (CAD) to support more efficient adjudication of compensation claims from former gold miners with occupational lung disease in Southern Africa. In doing so, we apply a bio-ethical lens that considers the principles of beneficence, non-maleficence, autonomy and justice and add explicability as a core principle. We draw on the AI literature, our research on CAD validation and process efficiency, as well as apprehensions of users and stakeholders. Issues of concern included AI accuracy, biased training of AI systems, data privacy, impact on human skill development, transparency and accountability in AI use, as well as intellectual property ownership. We discuss ways in which each of these potential obstacles to successful use of CAD could be mitigated. We conclude that efforts to overcoming technical challenges in applying AI must be accompanied from the onset by attention to ensuring its ethical use.
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Affiliation(s)
- Jerry M. Spiegel
- School of Population and Public Health, The University of British Columbia, Vancouver, BC, Canada
| | - Rodney Ehrlich
- School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa
| | - Annalee Yassi
- School of Population and Public Health, The University of British Columbia, Vancouver, BC, Canada
| | | | | | - Karen Lockhart
- School of Population and Public Health, The University of British Columbia, Vancouver, BC, Canada
| | - Stephen Barker
- School of Population and Public Health, The University of British Columbia, Vancouver, BC, Canada
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Ehrlich R, Akugizibwe P, Siegfried N, Rees D. The association between silica exposure, silicosis and tuberculosis: a systematic review and meta-analysis. BMC Public Health 2021; 21:953. [PMID: 34016067 PMCID: PMC8136154 DOI: 10.1186/s12889-021-10711-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 03/25/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND While the association between occupational inhalation of silica dust and pulmonary tuberculosis has been known for over a century, there has never been a published systematic review, particularly of experience in the current era of less severe silicosis and treatable tuberculosis. We undertook a systematic review of the evidence for the association between (1) silicosis and pulmonary tuberculosis, and (2) silica exposure and pulmonary tuberculosis controlling for silicosis, and their respective exposure-response gradients. METHODS We searched PUBMED and EMBASE, and selected studies according to a priori inclusion criteria. We extracted, summarised and pooled the results of published case-control and cohort studies of silica exposure and/or silicosis and incident active tuberculosis. Study quality was assessed on the Newcastle-Ottawa Scale. Where meta-analysis was possible, effect estimates were pooled using inverse-variance weighted random-effects models. Otherwise narrative and graphic synthesis was undertaken. Confidence regarding overall effect estimates was assessed using the GRADE schema. RESULTS Nine studies met the inclusion criteria. Meta-analysis of eight studies of silicosis and tuberculosis yielded a pooled relative risk of 4.01 (95% confidence interval (CI) 2.88, 5.58). Exposure-response gradients were strong with a low silicosis severity threshold for increased risk. Our GRADE assessment was high confidence in a strong association. Meta-analysis of five studies of silica exposure controlling for or excluding silicosis yielded a pooled relative risk of 1.92 (95% CI 1.36, 2.73). Exposure-response gradients were observable in individual studies but not finely stratified enough to infer an exposure threshold. Our GRADE assessment was low confidence in the estimated effect owing to inconsistency and use of proxies for silica exposure. CONCLUSIONS The evidence is robust for a strongly elevated risk of tuberculosis with radiological silicosis, with a low disease severity threshold. The effect estimate is more uncertain for silica exposure without radiological silicosis. Research is needed, particularly cohort studies measuring silica exposure in different settings, to characterise the effect more accurately as well as the silica exposure threshold that could be used to prevent excess tuberculosis risk.
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Affiliation(s)
- Rodney Ehrlich
- School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa
| | - Paula Akugizibwe
- School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa
| | - Nandi Siegfried
- Independent Clinical Epidemiologist, Cape Town, South Africa
- Department of Psychiatry and Mental Health, University of Cape Town, Cape Town, South Africa
| | - David Rees
- National Institute for Occupational Health, Johannesburg, South Africa
- School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
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Knight D, Ehrlich R, Cois A, Fielding K, Grant AD, Churchyard G. Predictors of silicosis and variation in prevalence across mines among employed gold miners in South Africa. BMC Public Health 2020; 20:829. [PMID: 32487111 PMCID: PMC7268682 DOI: 10.1186/s12889-020-08876-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 05/07/2020] [Indexed: 01/15/2023] Open
Abstract
Background The stated intention to eliminate silicosis from the South African goldmining industry as well as current programmes to find and compensate ex-miners with silicosis require an understanding of variation in silicosis prevalence across the industry. We aimed to identify the predictors of radiological silicosis in a large sample of working miners across gold mines in South Africa. Methods Routine surveillance chest radiographs were collected from 15 goldmine “clusters” in a baseline survey undertaken in preparation for a separate tuberculosis isoniazid prophylaxis trial. All images were read for silicosis by a health professional experienced in using the International Labour Organisation (ILO) classification. Profusion thresholds of > 1/0 and > 1/1 were used. Demographic and occupational information was obtained by questionnaire. Predictors of silicosis were examined in a multivariable logistic regression model, including age, gender, racial ascription, country of origin, years since starting mine employment, mine shaft, skill category, underground work status and tuberculosis. Results The crude silicosis prevalence at ILO > 1/1 was 3.8% [95% confidence interval (CI) 3.5–4.1%]. The range across mine shafts was 0.8–6.9%. After adjustment for covariates, the interquartile range across shafts was reduced from 2.4 to 1.2%. Black miners [adjusted odds ratio (aOR) 2.8; 95% CI 1.1–7.2] and miners in full-time underground work (aOR 2.1; 95% CI 1.3–3.4) had substantially elevated odds of silicosis, while workers from Mozambique had lower odds (aOR 0.54; 95% CI 0.38–0.77). Silicosis odds rose sharply with both age and years since starting in the industry (p for linear trend < 0.005), with 95.5% of affected miners having > 15 years since first exposure and 2.2% < 10 years. Conclusions In surveillance of silicosis in working gold miners time since first exposure remains a powerful predictor. Age appears to be an independent predictor, while the detection of radiological silicosis in short-service miners requires attention. Public risk reporting by mines should include factors bearing on silicosis prevalence, specifically dust concentrations, with independent verification. Studies of silicosis and tuberculosis in ex-miners are needed, supported by an accessible electronic database of the relevant medical and dust exposure records of all gold miners.
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Affiliation(s)
- Dave Knight
- International SOS, Singapore, Singapore. .,Centre for Environmental and Occupational Health Research, School of Public Health and Family Medicine, University of Cape Town, PO Box 43915, Scarborough, Cape Town, 7975, South Africa.
| | - Rodney Ehrlich
- Centre for Environmental and Occupational Health Research, School of Public Health and Family Medicine, University of Cape Town, PO Box 43915, Scarborough, Cape Town, 7975, South Africa
| | - Annibale Cois
- Burden of Disease Research Unit, South African Medical Research Council, Parow Valley, South Africa.,Division of Epidemiology and Biostatistics, School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa
| | - Katherine Fielding
- School of Public Health, University of the Witwatersrand, Johannesburg, South Africa.,London School of Hygiene and Tropical Medicine, London, UK
| | - Alison D Grant
- School of Public Health, University of the Witwatersrand, Johannesburg, South Africa.,London School of Hygiene and Tropical Medicine, London, UK.,Africa Health Research Institute, School of Nursing and Public Health, University of KwaZulu-Natal, Durban, South Africa
| | - Gavin Churchyard
- School of Public Health, University of the Witwatersrand, Johannesburg, South Africa.,London School of Hygiene and Tropical Medicine, London, UK.,The Aurum Institute, Johannesburg, South Africa
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10
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Zhao Y, Xu G, Li H, Chang M, Guan Y, Li Y, Wu W, Yao S. Overexpression of endogenous lipoic acid synthase attenuates pulmonary fibrosis induced by crystalline silica in mice. Toxicol Lett 2020; 323:57-66. [PMID: 32017981 DOI: 10.1016/j.toxlet.2020.01.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 01/23/2020] [Accepted: 01/25/2020] [Indexed: 02/05/2023]
Abstract
Oxidative stress and inflammatory processes are proposed to mediate the development of silicosis. However, antioxidant therapy has not produced consistent results during the treatment of silicosis. α-Lipoic acid synthesized by lipoic acid synthase is a powerful anti-oxidant and helps protect mitochondria. Thus far, the effect of endogenous α-Lipoic acid on silicosis has not been elucidated yet. We established an experimental model of silicosis with wildtype and LiasH/H mice, a new antioxidant mouse model which has overexpressed Lias gene (∼150 %) relative to its wild type counterpart. We systemically examined main pathological changes of pulmonary fibrosis, and explored α-lipoic acid effects on oxidative stress, inflammatory and pulmonary fibrosis biomarkers in silica-instillated mice. In LiasH/H mice over-expression of lipoic acid alleviated the severity of major pathological alterations in the early stage of pulmonary fibrosis induced by silica compared with wild type mice. Silica significantly increased oxidative stress in both wild type and LiasH/H mice. The antioxidant defense was strengthen including increased NRF2 and LIAS production in LiasH/H mice. Relieved oxidative stress resulted in decreased inflammatory response and secretion of chemokines. LiasH/H mice reduced chronic inflammatory response and inhibition of NF-κB activity after silica instillation. The LiasH/H mouse model overexpression of lipoic acid synthase gene retarded the development of silica-induced pulmonary fibrosis. Strengthen antioxidant defense by increased lipoic acid synthase is a potential strategy for protection against silica-induced pulmonary fibrosis.
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Affiliation(s)
- Yingzheng Zhao
- School of Public Health, North China University of Science and Technology, Tangshan, Hebei Province 063009, PR China; School of Public Health, Xinxiang Medical University, Xinxiang, Henan Province 453003, PR China
| | - Guangcui Xu
- School of Public Health, Xinxiang Medical University, Xinxiang, Henan Province 453003, PR China
| | - Haibin Li
- School of Public Health, North China University of Science and Technology, Tangshan, Hebei Province 063009, PR China; School of Public Health, Xinxiang Medical University, Xinxiang, Henan Province 453003, PR China
| | - Meiyu Chang
- School of Public Health, Xinxiang Medical University, Xinxiang, Henan Province 453003, PR China
| | - Yi Guan
- School of Public Health, North China University of Science and Technology, Tangshan, Hebei Province 063009, PR China
| | - Yuchun Li
- School of Public Health, Xinxiang Medical University, Xinxiang, Henan Province 453003, PR China
| | - Weidong Wu
- School of Public Health, Xinxiang Medical University, Xinxiang, Henan Province 453003, PR China
| | - Sanqiao Yao
- School of Public Health, North China University of Science and Technology, Tangshan, Hebei Province 063009, PR China; School of Public Health, Xinxiang Medical University, Xinxiang, Henan Province 453003, PR China.
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