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Nicolaou L, Sylvies F, Veloso I, Lord K, Chandyo RK, Sharma AK, Shrestha LP, Parker DL, Thygerson SM, DeCarlo PF, Ramachandran G, Checkley W. Brick kiln pollution and its impact on health: A systematic review and meta-analysis. ENVIRONMENTAL RESEARCH 2024:119220. [PMID: 38797466 DOI: 10.1016/j.envres.2024.119220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 05/20/2024] [Accepted: 05/21/2024] [Indexed: 05/29/2024]
Abstract
Brick kiln emissions adversely affect air pollution and the health of workers and individuals living near the kilns; however, evidence of their impacts remains limited. We conducted a systematic review of brick kiln pollution (emissions, source contributions and personal exposures) and its effects on health. We extracted articles from electronic databases and through manual citation searching. We estimated pooled, sample-size-weighted means and standard deviations for personal exposures by job type; computed mean emission factors and pollutant concentrations by brick kiln design; and meta-analyzed differences in means or proportions for health outcomes between brick kiln workers and controls or for participants living near or far away from kilns. We identified 104 studies; 74 were conducted in South Asia. The most evaluated pollutants were particulate matter (PM; n=48), sulfur dioxide (SO2; n=24) and carbon monoxide (CO; n=22), and the most evaluated health outcomes were respiratory health (n=34) and musculoskeletal disorders (n=9). PM and CO emissions were higher among traditional than improved brick kilns. Mean respirable silica exposures were only measured in 4 (4%) studies and were as high as 620 μg/m3, exceeding the NIOSH recommended exposure limit by a factor of over 12. Brick kiln workers had consistently worse lung function, more respiratory symptoms, more musculoskeletal complaints, and more inflammation when compared to unexposed participants across studies; however, most studies had a small sample size and did not fully describe methods used for sampling or data collection. On average, brick kiln workers had worse health outcomes when compared to unexposed controls but study quality supporting the evidence was low. Few studies reported silica concentrations or personal exposures, but the few that did suggest that exposures are high. Further research is needed to better understand the relationship between brick kiln pollution and health among workers, and to evaluate exposure mitigation strategies.
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Affiliation(s)
- Laura Nicolaou
- Division of Pulmonary and Critical Care, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA; Center for Global Non-Communicable Disease Research and Training, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA; Department of Environmental Health and Engineering, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, USA
| | - Fiona Sylvies
- Center for Global Non-Communicable Disease Research and Training, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA
| | - Isabel Veloso
- Center for Global Non-Communicable Disease Research and Training, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA
| | - Katherine Lord
- Center for Global Non-Communicable Disease Research and Training, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA
| | - Ram K Chandyo
- Kathmandu Medical College, Sinamangal, Kathmandu, Nepal
| | - Arun K Sharma
- Institute of Medicine, Tribhuvan University Teaching Hospital, Kathmandu, Nepal
| | - Laxman P Shrestha
- Institute of Medicine, Tribhuvan University Teaching Hospital, Kathmandu, Nepal
| | - David L Parker
- University of Minnesota School of Public Health, Minneapolis, USA
| | | | - Peter F DeCarlo
- Department of Environmental Health and Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, Maryland, USA
| | - Gurumurthy Ramachandran
- Department of Environmental Health and Engineering, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, USA
| | - William Checkley
- Division of Pulmonary and Critical Care, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA; Center for Global Non-Communicable Disease Research and Training, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA; Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, USA.
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Howlett P, Mousa H, Said B, Mbuya A, Kon OM, Mpagama S, Feary J. Silicosis, tuberculosis and silica exposure among artisanal and small-scale miners: A systematic review and modelling paper. PLOS GLOBAL PUBLIC HEALTH 2023; 3:e0002085. [PMID: 37733799 PMCID: PMC10513209 DOI: 10.1371/journal.pgph.0002085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 08/30/2023] [Indexed: 09/23/2023]
Abstract
An estimated 44 million artisanal and small-scale miners (ASM), largely based in developing economies, face significant occupational risks for respiratory diseases which have not been reviewed. We therefore aimed to review studies that describe silicosis and tuberculosis prevalence and respirable crystalline silica (RCS) exposures among ASM and use background evidence to better understand the relationship between exposures and disease outcomes. We searched PubMed, Web of Science, Scopus and Embase for studies published before the 24th March 2023. Our primary outcome of interest was silicosis or tuberculosis among ASM. Secondary outcomes included measurements of respirable dust or silica, spirometry and prevalence of respiratory symptoms. A systematic review and narrative synthesis was performed and risk of bias assessed using the Joanna Briggs Prevalence Critical Appraisal Tool. Logistic and Poisson regression models with predefined parameters were used to estimate silicosis prevalence and tuberculosis incidence at different distributions of cumulative silica exposure. We identified 18 eligible studies that included 29,562 miners from 13 distinct populations in 10 countries. Silicosis prevalence ranged from 11 to 37%, despite four of five studies reporting an average median duration of mining of <6 years. Tuberculosis prevalence was high; microbiologically confirmed disease ranged from 1.8 to 6.1% and clinical disease 3.0 to 17%. Average RCS intensity was very high (range 0.19-89.5 mg/m3) and respiratory symptoms were common. Our modelling demonstrated decreases in cumulative RCS are associated with reductions in silicosis and tuberculosis, with greater reductions at higher mean exposures. Despite potential selection and measurement bias, prevalence of silicosis and tuberculosis were high in the studies identified in this review. Our modelling demonstrated the greatest respiratory health benefits of reducing RCS are in those with highest exposures. ASM face a high occupational respiratory disease burden which can be reduced by low-cost and effective reductions in RCS.
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Affiliation(s)
- Patrick Howlett
- National Heart & Lung Institute, Imperial College London, London, United Kingdom
| | - Hader Mousa
- Centre for Occupational and Environmental Health, Kigali, Rwanda
| | - Bibie Said
- Kibong’oto Infectious Disease Hospital, Kilimanjaro, Tanzania
| | - Alexander Mbuya
- Kibong’oto Infectious Disease Hospital, Kilimanjaro, Tanzania
| | - Onn Min Kon
- National Heart & Lung Institute, Imperial College London, London, United Kingdom
| | - Stellah Mpagama
- Kibong’oto Infectious Disease Hospital, Kilimanjaro, Tanzania
| | - Johanna Feary
- National Heart & Lung Institute, Imperial College London, London, United Kingdom
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Su X, Kong X, Yu X, Zhang X. Incidence and influencing factors of occupational pneumoconiosis: a systematic review and meta-analysis. BMJ Open 2023; 13:e065114. [PMID: 36858466 PMCID: PMC9980323 DOI: 10.1136/bmjopen-2022-065114] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/03/2023] Open
Abstract
OBJECTIVES To determine the incidence of pneumoconiosis worldwide and its influencing factors. DESIGN Systematic review and meta-analysis. SETTING Cohort studies on occupational pneumoconiosis. PARTICIPANTS PubMed, Embase, the Cochrane Library and Web of Science were searched until November 2021. Studies were selected for meta-analysis if they involved at least one variable investigated as an influencing factor for the incidence of pneumoconiosis and reported either the parameters and 95% CIs of the risk fit to the data, or sufficient information to allow for the calculation of those values. PRIMARY OUTCOME MEASURES The pooled incidence of pneumoconiosis and risk ratio (RR) and 95% CIs of influencing factors. RESULTS Our meta-analysis included 19 studies with a total of 335 424 participants, of whom 29 972 developed pneumoconiosis. The pooled incidence of pneumoconiosis was 0.093 (95% CI 0.085 to 0.135). We identified the following influencing factors: (1) male (RR 3.74; 95% CI 1.31 to 10.64; p=0.01), (2) smoking (RR 1.80; 95% CI 1.34 to 2.43; p=0.0001), (3) tunnelling category (RR 4.75; 95% CI 1.96 to 11.53; p<0.0001), (4) helping category (RR 0.07; 95% CI 0.13 to 0.16; p<0.0001), (5) age (the highest incidence occurs between the ages of 50 and 60), (6) duration of dust exposure (RR 4.59, 95% CI 2.41 to 8.74, p<0.01) and (7) cumulative total dust exposure (CTD) (RR 34.14, 95% CI 17.50 to 66.63, p<0.01). A dose-response analysis revealed a significant positive linear dose-response association between the risk of pneumoconiosis and duration of exposure and CTD (P-non-linearity=0.10, P-non-linearity=0.16; respectively). The Pearson correlation analysis revealed that silicosis incidence was highly correlated with cumulative silica exposure (r=0.794, p<0.001). CONCLUSION The incidence of pneumoconiosis in occupational workers was 0.093 and seven factors were found to be associated with the incidence, providing some insight into the prevention of pneumoconiosis. PROSPERO REGISTRATION NUMBER CRD42022323233.
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Affiliation(s)
- Xuesen Su
- The First College for Clinical Medicine, Shanxi Medical University, Taiyuan, Shanxi, China
- The National Health Commission Key Laboratory of Pneumoconiosis (Shanxi, China) Project, First Hospital of Shanxi Medical University, Taiyuan, Shanxi, China
| | - Xiaomei Kong
- The National Health Commission Key Laboratory of Pneumoconiosis (Shanxi, China) Project, First Hospital of Shanxi Medical University, Taiyuan, Shanxi, China
- Department of Pulmonary and Critical Care Medicine, First Hospital of Shanxi Medical University, Taiyuan, Shanxi, China
| | - Xiao Yu
- The National Health Commission Key Laboratory of Pneumoconiosis (Shanxi, China) Project, First Hospital of Shanxi Medical University, Taiyuan, Shanxi, China
- Department of Pulmonary and Critical Care Medicine, First Hospital of Shanxi Medical University, Taiyuan, Shanxi, China
| | - Xinri Zhang
- The National Health Commission Key Laboratory of Pneumoconiosis (Shanxi, China) Project, First Hospital of Shanxi Medical University, Taiyuan, Shanxi, China
- Department of Pulmonary and Critical Care Medicine, First Hospital of Shanxi Medical University, Taiyuan, Shanxi, China
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Rumchev K, Hoang DV, Lee A. Case Report: Exposure to Respirable Crystalline Silica and Respiratory Health Among Australian Mine Workers. Front Public Health 2022; 10:798472. [PMID: 35769775 PMCID: PMC9234445 DOI: 10.3389/fpubh.2022.798472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 05/23/2022] [Indexed: 11/13/2022] Open
Abstract
Occupational exposure to respirable crystalline silica (RCS) is common in a range of industries, including mining, and has been associated with adverse health effects such as silicosis, lung cancer, and non-malignant respiratory diseases. This study used a large population database of 6,563 mine workers from Western Australia who were examined for personal exposure to RCS between 2001 and 2012. A standardized respiratory questionnaire was also administered to collect information related to their respiratory health. Logistic regression analyses were performed to ascertain the association between RCS concentrations and the prevalence of respiratory symptoms among mine workers. The estimated exposure levels of RCS (geometric mean 0.008mg/m3, GSD 4.151) declined over the study period (p < 0.001) and were below the exposure standard of 0.05 mg/m3. Miners exposed to RCS had a significantly higher prevalence of phlegm (p = 0.017) and any respiratory symptom (p = 0.013), even at concentrations within the exposure limit. Miners are susceptible to adverse respiratory health effects at low levels of RCS exposure. More stringent prevention strategies are therefore recommended to protect mine workers from RCS exposures.
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Affiliation(s)
- Krassi Rumchev
- School of Population Health, Curtin University, Perth, WA, Australia
- *Correspondence: Krassi Rumchev
| | - Dong Van Hoang
- Department of Epidemiology and Prevention, Center for Clinical Sciences, National Center for Global Health and Medicine, Tokyo, Japan
| | - Andy Lee
- School of Population Health, Curtin University, Perth, WA, Australia
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Bielsa S, Guitart A, Esquerda A, Fernández-Pacheco R, Baranguán MT, Ibarra A, Porcel JM. Some pleural effusions labeled as idiopathic could be produced by the inhalation of silica. Pleura Peritoneum 2022; 7:27-33. [PMID: 35602920 PMCID: PMC9069498 DOI: 10.1515/pp-2021-0135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 12/15/2021] [Indexed: 11/15/2022] Open
Abstract
Abstract
Objectives
Exposure to silica nanoparticles has been associated with pleural effusions (PEs) in animal models and case series. We hypothesized that some PEs labelled as “idiopathic” could, in fact, be secondary to inhalation of silica.
Methods
A retrospective case control study was designed utilizing a prospectively maintained pleural database. Cases, represented by idiopathic PEs, were matched by age and gender to control patients who had been diagnosed with malignant, cardiac, or infectious PEs. A survey consisting of questions about occupational life and possibility of silica inhalation was conducted. In a subgroup of patients, pleural fluid concentrations of silica were quantified by plasma atomic emission spectrometry analysis. Also, the pleural biopsy of a silica-exposed case was subjected to an energy dispersive X-ray spectroscopy (EDX) to identify the mineral, the size of which was determined by electron microscopy.
Results
A total of 118 patients (59 cases and 59 controls) completed the survey. There were 25 (42%, 95% CI 31–55%) and 13 (22%, 95% CI 13–34%) silica-exposed workers in case and control groups, respectively. The exposure attributable fraction was 0.62 (95% CI 0.14–0.83). Four of eight exposed cases showed detectable levels of silica in the pleural fluid (mean 2.37 mg/L), as compared to none of 16 tested controls. Silica nanoparticles of 6–7 nm were identified in the pleural biopsy of an exposed case patient.
Conclusions
It is plausible that some idiopathic PEs could actually be caused by occupational silica inhalation.
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Affiliation(s)
- Silvia Bielsa
- Department of Internal Medicine , Pleural Medicine Unit, Arnau de Vilanova University Hospital, Biomedical Research Institute of Lleida (IRBLleida), University of Lleida , Lleida , Spain
| | - Ana Guitart
- Chemical Analysis Service , Science Faculty, Zaragoza University, Zaragoza , Spain
| | - Aureli Esquerda
- Department of Laboratory Medicine , Arnau de Vilanova University Hospital, IRBLleida , Lleida , Spain
| | - Rodrigo Fernández-Pacheco
- Aragon Nanoscience Institute , Advanced Microscopy Laboratory, Zaragoza University , Zaragoza , Spain
| | | | - Alfonso Ibarra
- Aragon Nanoscience Institute , Advanced Microscopy Laboratory, Zaragoza University , Zaragoza , Spain
| | - José M. Porcel
- Department of Internal Medicine , Pleural Medicine Unit, Arnau de Vilanova University Hospital, Biomedical Research Institute of Lleida (IRBLleida), University of Lleida , Lleida , Spain
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Shao Y, Hwang J, MacLehose RF, Alexander BH, Mandel JH, Raynor PC, Ramachandran G. Reconstructing Historical Exposures to Respirable Dust and Respirable Silica in the Taconite Mining Industry for 1955-2010. Ann Work Expo Health 2021; 66:459-471. [PMID: 34864842 DOI: 10.1093/annweh/wxab099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 09/29/2021] [Accepted: 10/21/2021] [Indexed: 11/12/2022] Open
Abstract
The goal of this study was to reconstruct the historical respirable silica (RS) and respirable dust (RD) exposures of workers in the Minnesota taconite industry from 1955 to 2010 as part of several epidemiological studies for assessing the association between exposure to components of taconite dusts and the development of respiratory diseases. A job-exposure matrix (JEM) was developed that uses 9127 RS and 19 391 RD occupational hygiene historical measurements. Historical RS and RD data were extracted from several sources and were grouped into seven mines and then into eight departments [Concentrating, Crushing, Janitor, Mining, Office/control room, Pelletizing, Shop (mobile), and Shop (stationary)]. Within each department, we applied a two-level random-intercept regression model which assumes that the natural log of Y (RD or RS concentration) changes over time at a constant rate. Among all predicted RD and RS values, we found that larger RD values were located in the following departments: Crushing, Concentrating, Pelletizing, and Shop (mobile). Larger RS values were located only in either Crushing or Shop (mobile). The annual rates of change for historical RD and RS exposures were between -3.3 and 3.2%. The silica percentage in the dust varied by mine/department with the highest value of 29.3% in Mine F (Crushing) and the lowest value of 2.1% in Mine B (Pelletizing). The predicted historical RD and RS arithmetic mean exposures ranged between <0.075 and 3.14 mg m-3, and between <0.005 and 0.36 mg m-3, respectively. The result of this study is a JEM by mine, department, and year for RD and RS for epidemiological studies.
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Affiliation(s)
- Yuan Shao
- Division of Environmental Health Sciences, University of Minnesota, Minneapolis, MN, USA.,Department of Environmental Health and Engineering, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Jooyeon Hwang
- Department of Occupational and Environmental Health, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Richard F MacLehose
- Division of Epidemiology & Community Health, University of Minnesota, Minneapolis, MN, USA
| | - Bruce H Alexander
- Division of Environmental Health Sciences, University of Minnesota, Minneapolis, MN, USA
| | - Jeffrey H Mandel
- Division of Environmental Health Sciences, University of Minnesota, Minneapolis, MN, USA
| | - Peter C Raynor
- Division of Environmental Health Sciences, University of Minnesota, Minneapolis, MN, USA
| | - Gurumurthy Ramachandran
- Department of Environmental Health and Engineering, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
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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: 34] [Impact Index Per Article: 11.3] [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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Wang D, Zhou M, Liu Y, Ma J, Yang M, Shi T, Chen W. Comparison of Risk of Silicosis in Metal Mines and Pottery Factories. Chest 2020; 158:1050-1059. [DOI: 10.1016/j.chest.2020.03.054] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Revised: 03/16/2020] [Accepted: 03/19/2020] [Indexed: 11/27/2022] Open
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Wen C, Wen X, Li R, Su S, Xu H. Silicosis in rhinestone-manufacturing workers in South China. Occup Med (Lond) 2019; 69:475-481. [PMID: 31504839 DOI: 10.1093/occmed/kqz107] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Silicosis is caused by long-term exposure to silica dust. Crystal rhinestone workers can be exposed to high levels of silica dust and are at risk of silicosis. AIMS To explore silicosis cases, silica dust exposure and control measures in a rhinestone factory in South China. METHODS We extracted and analysed data on new silicosis cases reported to China's occupational disease and occupational health information monitoring system between 2006 and 2012 from a rhinestone factory in South China. We measured the quartz content of bulk dust, static total and respirable dust samples. RESULTS Ninety-eight silicosis cases were reported between 2006 and 2012. The mean duration of silica dust exposure was 9.2 years (range 3-16). Drilling and polishing workers accounted for 96 (98%) of cases. We collected 1479 static samples including 690 total dust and 789 respirable dust samples. Mean dust levels for drilling were 1.01 mg/m3 (range 0.20-3.80) for total dust and 0.51 mg/m3 (range 0.04-1.70) for respirable dust. Mean dust levels for polishing were 0.59 mg/m3 (range 0.20-2.10) for total dust and 0.28 mg/m3 (range 0.08-0.71) for respirable dust. Over a third [289/789 (37%)] of total dust samples and 129/690 (19%) respirable dust samples exceeded the national permissible exposure limit. CONCLUSION Exposure to silica dust, ineffective dust control measures and inefficient health surveillance may have contributed to the incidence of silicosis in the factory we studied. Identification of silica dust exposure and effective dust control measures would reduce the risk of silicosis in rhinestone workers.
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Affiliation(s)
- C Wen
- Guangdong Province Hospital for Occupational Disease Prevention and Treatment, Guangdong, Guangzhou, China
| | - X Wen
- Guangdong Province Hospital for Occupational Disease Prevention and Treatment, Guangdong, Guangzhou, China
| | - R Li
- Guangdong Province Hospital for Occupational Disease Prevention and Treatment, Guangdong, Guangzhou, China
| | - S Su
- Guangdong Province Hospital for Occupational Disease Prevention and Treatment, Guangdong, Guangzhou, China
| | - H Xu
- Guangdong Province Hospital for Occupational Disease Prevention and Treatment, Guangdong, Guangzhou, China
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10
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Konečný P, Ehrlich R, Gulumian M, Jacobs M. Immunity to the Dual Threat of Silica Exposure and Mycobacterium tuberculosis. Front Immunol 2019; 9:3069. [PMID: 30687311 PMCID: PMC6334662 DOI: 10.3389/fimmu.2018.03069] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 12/11/2018] [Indexed: 01/28/2023] Open
Abstract
Exposure to silica and the consequent development of silicosis are well-known health problems in countries with mining and other dust producing industries. Apart from its direct fibrotic effect on lung tissue, chronic and immunomodulatory character of silica causes susceptibility to tuberculosis (TB) leading to a significantly higher TB incidence in silica-exposed populations. The presence of silica particles in the lung and silicosis may facilitate initiation of tuberculous infection and progression to active TB, and exacerbate the course and outcome of TB, including prognosis and survival. However, the exact mechanisms of the involvement of silica in the pathological processes during mycobacterial infection are not yet fully understood. In this review, we focus on the host's immunological response to both silica and Mycobacterium tuberculosis, on agents of innate and adaptive immunity, and particularly on silica-induced immunological modifications in co-exposure that influence disease pathogenesis. We review what is known about the impact of silica and Mycobacterium tuberculosis or their co-exposure on the host's immune system, especially an impact that goes beyond an exclusive focus on macrophages as the first line of the defense. In both silicosis and TB, acquired immunity plays a major role in the restriction and/or elimination of pathogenic agents. Further research is needed to determine the effects of silica in adaptive immunity and in the pathogenesis of TB.
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Affiliation(s)
- Petr Konečný
- Centre for Environmental and Occupational Health, School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa.,Division of Immunology, Department of Pathology and Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Rodney Ehrlich
- Centre for Environmental and Occupational Health, School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa
| | - Mary Gulumian
- National Health Laboratory Service, Department of Toxicology and Biochemistry, National Institute for Occupational Health, Johannesburg, South Africa.,Division of Molecular Medicine and Haematology, University of the Witwatersrand, Johannesburg, South Africa.,National Health Laboratory Service, Johannesburg, South Africa
| | - Muazzam Jacobs
- Division of Immunology, Department of Pathology and Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,National Health Laboratory Service, Johannesburg, South Africa.,Immunology of Infectious Disease Research Unit, South African Medical Research Council, Cape Town, South Africa
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11
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Keil AP, Richardson DB, Westreich D, Steenland K. Estimating the Impact of Changes to Occupational Standards for Silica Exposure on Lung Cancer Mortality. Epidemiology 2018; 29:658-665. [PMID: 29870429 PMCID: PMC6066423 DOI: 10.1097/ede.0000000000000867] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Respiratory exposure to silica is associated with the risk of death owing to malignant and nonmalignant disease. 2.3 million US workers are exposed to silica. Occupational exposure limits for silica are derived from a number of lines of evidence, including observational studies. Observational studies may be subject to healthy worker survivor bias, which could result in underestimates of silica's impact on worker mortality and, in turn, bias risk estimates for occupational exposure limits. METHODS Using data on 65,999 workers pooled across multiple industries, we estimate the impacts of several hypothetical occupational exposure limits on silica exposure on lung cancer and all-cause mortality. We use the parametric g-formula, which can account for healthy worker survivor bias. RESULTS Assuming we could eliminate occupational exposure, we estimate that there would be 20.7 fewer deaths per 1,000 workers in our pooled study by age 80 (95% confidence interval = 14.5, 26.8), including 3.91 fewer deaths owing to lung cancer (95% CI = 1.53, 6.30). Less restrictive interventions demonstrated smaller but still substantial risk reductions. CONCLUSIONS Our results suggest that occupational exposure limits for silica can be further strengthened to reduce silica-associated mortality and illustrate how current risk analysis for occupational limits can be improved.
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Affiliation(s)
- Alexander P Keil
- From the Department of Epidemiology, University of North Carolina, Chapel Hill, NC
| | - David B Richardson
- From the Department of Epidemiology, University of North Carolina, Chapel Hill, NC
| | - Daniel Westreich
- From the Department of Epidemiology, University of North Carolina, Chapel Hill, NC
| | - Kyle Steenland
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA
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12
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Morbidity and Health Risk Factors Among New Mexico Miners: A Comparison Across Mining Sectors. J Occup Environ Med 2018; 59:789-794. [PMID: 28697062 DOI: 10.1097/jom.0000000000001078] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE This study examines differences in chronic health outcomes between coal, uranium, metal, and nonmetal miners. METHODS In a cross-sectional study using data from a health screening program for current and former New Mexico miners, log-binomial logistic regression models were used to estimate relative risks of respiratory and heart disease, cancer, osteoarthritis, and back pain associated with mining in each sector as compared with coal, adjusting for other relevant risk factors. RESULTS Differential risks in angina, pulmonary symptoms, asthma, cancer, osteoarthritis, and back pain between mining sectors were found. CONCLUSIONS New Mexico miners experience different chronic health challenges across sectors. These results demonstrate the importance of using comparable data to understand how health risks differ across mining sectors. Further investigation among a broader geographic population of miners will help identify the health priorities and needs in each sector.
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Andraos C, Utembe W, Gulumian M. Exceedance of environmental exposure limits to crystalline silica in communities surrounding gold mine tailings storage facilities in South Africa. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 619-620:504-516. [PMID: 29156270 DOI: 10.1016/j.scitotenv.2017.11.135] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 11/09/2017] [Accepted: 11/12/2017] [Indexed: 06/07/2023]
Abstract
BACKGROUND Unlike occupational silica exposures, the association between non-occupational silica exposures and adverse health effects is not well researched, despite its occurrence in communities close to dust-generating sources such as tailings storage facilities (TSFs). Recent studies have shown that communities surrounding TSFs in South Africa often complain about the onset of dust-related health effects. Even though international interim non-occupational crystalline silica limits have been established, South Africa is yet to enforce its own limits for residential areas close to TSF sites. OBJECTIVE The objective of the study was to assess the need to enforce non-occupational crystalline silica limits for South Africa. METHODS The methods involved (1) Quantifying the silica polymorph content in bulk dust collected from TSFs in South Africa; (2) Assessing the possibility of the dust to reach surrounding communities through ambient and personal filter sampling and; (3) Conducting risk characterisation for both cancer and non-cancer endpoints. RESULTS All bulk dust samples consisted mostly of crystalline silica (73.14-87.09%). Large percentages of nanoparticles were identified in all bulk samples (66.8-70.7%) indicating the possibility of the dust to lodge deep within the lungs. The crystalline silica levels obtained from ambient PM10 sampling and personal PM4 sampling all exceeded the international crystalline silica interim limits and reached maximum levels of 90 and 50.9μg·m-3, respectively. For three TSFs, sampling sites close to the TSFs showed higher PM4 silica levels compared to sites further from TSFs. Risk characterisation revealed the possibility of cancer and non-cancer health effects when chronically exposed to silica levels recorded during the study. CONCLUSION The results indicate unacceptable crystalline silica exposures in surrounding communities and the need for enforcement of an ambient silica limit for South Africa.
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Affiliation(s)
- Charlene Andraos
- Toxicology Department, National Institute for Occupational Health, PO Box 4788, Johannesburg 2000, South Africa; Haematology and Molecular Medicine Department, University of the Witwatersrand, Private Bag 3, Wits, 2050 Johannesburg, South Africa.
| | - Wells Utembe
- Toxicology Department, National Institute for Occupational Health, PO Box 4788, Johannesburg 2000, South Africa.
| | - Mary Gulumian
- Toxicology Department, National Institute for Occupational Health, PO Box 4788, Johannesburg 2000, South Africa; Haematology and Molecular Medicine Department, University of the Witwatersrand, Private Bag 3, Wits, 2050 Johannesburg, South Africa.
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Hwang J, Ramachandran G, Raynor PC, Alexander BH, Mandel JH. A comprehensive assessment of exposures to respirable dust and silica in the taconite mining industry. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE 2017; 14:377-388. [PMID: 28388309 DOI: 10.1080/15459624.2016.1263392] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
This study assessed the present-day levels (year 2010-2011) of exposure to respirable dust (RD) and respirable silica (RS) in taconite mines and evaluated how the mining process influences exposure concentrations. Personal samples (n = 679) were collected to assess exposure levels of workers to RD and RS at six mines in the Mesabi Iron Range of Minnesota. The RD and RS concentrations were measured using the National Institute for Occupational Safety and Health (NIOSH) 0600 and NIOSH 7500, respectively. Between-mine, between-SEG (similar exposure groups), within-SEG, and within-worker components of variability for RD and RS exposures were estimated using a two- or three-way nested random-effects ANOVA model. The majority of RD concentrations across all mines were below the Mine Safety and Health Administration (MSHA) Permissible Exposure Limit (PEL). The highest concentrations of RD were often observed in either the Pelletizing or Crushing departments, which are inherently dusty operations. With a few exceptions, the concentrations of RS in the crushing and concentrating processes were higher than those in the other mining processes, as well as higher than the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) for RS. The magnetic separation and flotation processes in the concentrating department reduced the levels of RS significantly, and lowered the percentage of quartz in RD in the pelletizing department. There was little variability among the six mines or between the two mineralogically distinct zones for either RD or RS exposures. The between-SEG variability for RS did not differ substantially across most of the mines and was a major component of exposure variance. The within-SEG (or between-worker) variance component was typically the smallest because in many instances one worker from a SEG within a mine was monitored multiple times. Some of these findings were affected by the degree of censoring in each SEG and mine, characteristics of the taconite rock, seasonal effects during sampling, or the tasks assigned to each job in that mine.
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Affiliation(s)
- Jooyeon Hwang
- a Division of Environmental Health Sciences , School of Public Health, University of Minnesota , Minneapolis , Minnesota
| | - Gurumurthy Ramachandran
- b Department of Environmental Health and Engineering , Bloomberg School of Public Health, Johns Hopkins University , Baltimore , Maryland
| | - Peter C Raynor
- a Division of Environmental Health Sciences , School of Public Health, University of Minnesota , Minneapolis , Minnesota
| | - Bruce H Alexander
- a Division of Environmental Health Sciences , School of Public Health, University of Minnesota , Minneapolis , Minnesota
| | - Jeffrey H Mandel
- a Division of Environmental Health Sciences , School of Public Health, University of Minnesota , Minneapolis , Minnesota
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Pulmonary hypertension and vascular remodeling in mice exposed to crystalline silica. Respir Res 2016; 17:160. [PMID: 27894297 PMCID: PMC5126840 DOI: 10.1186/s12931-016-0478-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 11/22/2016] [Indexed: 11/10/2022] Open
Abstract
Background Occupational and environmental exposure to crystalline silica may lead to the development of silicosis, which is characterized by inflammation and progressive fibrosis. A substantial number of patients diagnosed with silicosis develop pulmonary hypertension. Pulmonary hypertension associated with silicosis and with related restrictive lung diseases significantly reduces survival in affected subjects. An animal model of silicosis has been described previously however, the magnitude of vascular remodeling and hemodynamic effects of inhaled silica are largely unknown. Considering the importance of such information, this study investigated whether mice exposed to silica develop pulmonary hypertension and vascular remodeling. Methods C57BL6 mice were intratracheally injected with either saline or crystalline silica at doses 0.2 g/kg, 0.3 g/kg and 0.4 g/kg and then studied at day 28 post-exposure. Pulmonary hypertension was characterized by changes in right ventricular systolic pressure and lung histopathology. Results Mice exposed to saline showed normal lung histology and hemodynamic parameters while mice exposed to silica showed increased right ventricular systolic pressure and marked lung pathology characterized by a granulomatous inflammatory reaction and increased collagen deposition. Silica-exposed mice also showed signs of vascular remodeling with pulmonary artery muscularization, vascular occlusion, and medial thickening. The expression of pro-inflammatory genes such as TNF-α and MCP-1 was significantly upregulated as well as the expression of the pro-remodeling genes collagen type I, fibronectin and the metalloproteinases MMP-2 and TIMP-1. On the other hand, the expression of several vasculature specific genes involved in the regulation of endothelial function was significantly attenuated. Conclusions We characterized a new animal model of pulmonary hypertension secondary to pulmonary fibrosis induced by crystalline silica. Our data suggest that silica promotes the damage of the pulmonary vasculature through mechanisms that might involve endothelial dysfunction, inflammation, and vascular remodeling.
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Shen Y, Cui X, Rong Y, Zhang Z, Xiao L, Zhou T, Chen W. Exogenous Gas6 attenuates silica-induced inflammation on differentiated THP-1 macrophages. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2016; 45:222-226. [PMID: 27327525 DOI: 10.1016/j.etap.2016.05.029] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Revised: 05/27/2016] [Accepted: 05/29/2016] [Indexed: 06/06/2023]
Abstract
Growth arrest specific 6 (Gas6) has been reported to be related to the modulation of innate immunity. To investigate the potential effect of Gas6 on the regulation of inflammations induced by silica, differentiated THP-1 macrophages were exposed to different concentrations of silica for 6h and 24h. Additionally, silica-activated macrophages were treated with Gas6 antibody and Gas6 respectively. Expression levels of Gas6 and inflammatory cytokines (TNF-α, IL-1β and IL-6) were measured. Our results showed that both cell viability and Gas6 expression were suppressed by silica in dose-dependent manners. After pretreatment with Gas6 antibody, silica induced a significant decrease in cell viability and a significant increase in inflammatory cytokines at two time points. Moreover, addition of Gas6 significantly suppressed silica induced TNF-α, IL-1β and IL-6 levels in negative dose-dependent manners, not only in mRNA levels but also in protein levels. Our results suggested that exogenous Gas6 might attenuate inflammations induced by silica on macrophages.
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Affiliation(s)
- Yan Shen
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China; Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, State Key Laboratory of Environmental Health (Incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Xiuqing Cui
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China; Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, State Key Laboratory of Environmental Health (Incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Yi Rong
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China; Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, State Key Laboratory of Environmental Health (Incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Zhihong Zhang
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China; Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, State Key Laboratory of Environmental Health (Incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Lili Xiao
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China; Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, State Key Laboratory of Environmental Health (Incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Ting Zhou
- School of Public Health, Wuhan University of Science and Technology, Wuhan, Hubei 430065, China
| | - Weihong Chen
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China; Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, State Key Laboratory of Environmental Health (Incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.
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Ginsenoside Rg1 enhances lymphatic transport of intrapulmonary silica via VEGF-C/VEGFR-3 signaling in silicotic rats. Biochem Biophys Res Commun 2016; 472:182-8. [DOI: 10.1016/j.bbrc.2016.02.091] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 02/22/2016] [Indexed: 01/25/2023]
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OMIDIANIDOST A, GHASEMKHANI M, KAKOOEI H, SHAHTAHERI SJ, GHANBARI M. Risk Assessment of Occupational Exposure to Crystalline Silica in Small Foundries in Pakdasht, Iran. IRANIAN JOURNAL OF PUBLIC HEALTH 2016; 45:70-5. [PMID: 27057524 PMCID: PMC4822397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
BACKGROUND The term crystallized silica refers to the crystallized form of Sio2 and quartz, the most frequency composition in the earth's crust that can cause silicosis and lung cancer through occupational exposure and inhalation of its large quantities. METHODS Occupational exposure of workers in Pakdasht, Iran, in 2011 was investigated in four different casting processes in small foundries with less than 10 workers. Sampling respirable dust was collected on MCE filter, using HD cyclone at a flow rate of 2.2 lit/min. The filters were analyzed for dust using NIOSH Method 7601. Gravimetric and visible absorption spectrophotometer was used to determine amounts of inhalable dust and free silica, respectively. Risk assessment techniques were also used to predict silicosis and lung cancer. RESULTS Geometric means of occupational exposure to crystalline silica in 4 different casting processes were studied within the range of 0.009-0.04 mg/m(3). Mortality rate due to silicosis was in the range of 1-13.7 per 1000 persons exposed. Risk of mortality due to lung cancer in exposed workers in small casting workshops in Pakdasht, Iran ranged 4-16 per 1000 persons exposed based on geometric mean and 45 years of exposure. According to risk assessment, mortality due to silicosis, cumulative exposure of 96% of population was at an acceptable level of 1/1000. CONCLUSION Fifty percent of workers were exposed to crystalline silica dust in excess of Recommended Exposure Limit -NIOSH and Threshold Limit Value ACGIH (0.025 mg/m(3)). Several cases of silicosis and lung cancer are anticipated for this occupational group in near future.
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Affiliation(s)
- Ali OMIDIANIDOST
- Dept. of Occupational Health, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Mehdi GHASEMKHANI
- Dept. of Occupational Health, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran,Corresponding Author:
| | - Hossein KAKOOEI
- Dept. of Occupational Health, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Masud GHANBARI
- Dept. of Occupational Health Engineering, School of Public Health, Kermanshah University of Medical Sciences, Iran
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Yeoman KM, Halldin CN, Wood J, Storey E, Johns D, Laney AS. Current knowledge of US metal and nonmetal miner health: Current and potential data sources for analysis of miner health status. ARCHIVES OF ENVIRONMENTAL & OCCUPATIONAL HEALTH 2016; 71:119-26. [PMID: 25658684 PMCID: PMC4624608 DOI: 10.1080/19338244.2014.998330] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Little is known about the current health status of US metal and nonmetal (MNM) miners, in part because no health surveillance systems exist for this population. The National Institute for Occupational Safety and Health (NIOSH) is developing a program to characterize burden of disease among MNM miners. This report discusses current knowledge and potential data sources of MNM miner health. Recent national surveys were analyzed, and literature specific to MNM miner health status was reviewed. No robust estimates of disease prevalence were identified, and national surveys did not provide information specific to MNM miners. Because substantial gaps exist in the understanding of MNM miners' current health status, NIOSH plans to develop a health surveillance program for this population to guide intervention efforts to reduce occupational and personal risks for chronic illness.
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Affiliation(s)
- K. M. Yeoman
- Respiratory Health Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Spokane, Washington, USA
- CONTACT K. M. Yeoman Division of Respiratory Disease Studies, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, 315 East Montgomery Avenue, Spokane, WA99207, USA.
| | - C. N. Halldin
- Respiratory Health Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia, USA
| | - J. Wood
- Respiratory Health Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia, USA
| | - E. Storey
- Respiratory Health Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia, USA
| | - D. Johns
- Respiratory Health Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia, USA
| | - A. S. Laney
- Respiratory Health Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia, USA
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Wang W, Wang Y, Shi G. Experimental investigation on the infrared refraction and extinction properties of rock dust in tunneling face of coal mine. APPLIED OPTICS 2015; 54:10532-10540. [PMID: 26836882 DOI: 10.1364/ao.54.010532] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Comprehensive experimental research on the fundamental optical properties of dust pollution in a coal mine is presented. Rock dust generated in a tunneling roadway was sampled and the spectral complex refractive index within an infrared range of 2.5-25 μm was obtained by Fourier transform infrared spectroscopy measurement and Kramers-Kronig relation. Experimental results were validated to be consistent with equivalent optical constants simulated by effective medium theory based on component analysis of x-ray fluorescence, which illustrates that the top three mineral components are SiO2 (62.06%), Al2O3 (21.26%), and Fe2O3 (4.27%). The complex refractive index and the spatial distribution tested by a filter dust and particle size analyzer were involved in the simulation of extinction properties of rock dust along the tunneling roadway solved by the discrete ordinates method and Mie scattering model. The compared results illustrate that transmission is obviously enhanced with the increase of height from the floor but weakened with increasing horizontal distance from the air duct.
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Weng S, Wang L, Rong Y, Liu Y, Wang X, Guan H, Chen W. Effects of the Interactions between Dust Exposure and Genetic Polymorphisms in Nalp3, Caspase-1, and IL-1β on the Risk of Silicosis: A Case-Control Study. PLoS One 2015; 10:e0140952. [PMID: 26496436 PMCID: PMC4619690 DOI: 10.1371/journal.pone.0140952] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 10/03/2015] [Indexed: 01/03/2023] Open
Abstract
Objectives To evaluate the effects of the interactions between polymorphisms in Nalp3, caspase-1, and interleukin(IL)-1β genes and occupational dust exposure on the risk of silicosis. Methods We conducted a population-based case-control study in a large iron mine in China. Between January 2006 and December 2009, we identified 179 patients with silicosis to evaluate as cases and 201 individuals without silicosis to evaluate as controls. We estimated cumulative dust exposure (CDE) for all subjects and we genotyped polymorphisms in Nalp3, caspase-1, and IL-1β genes. We estimated odds ratios(ORs), 95% confidence intervals(95%CIs), and p-values using logistic regression models adjusted for selected confounders. Results After adjusting for age, smoking status, and CDE, subjects with the CT genotype of Ex4-849C>T in Nalp3 and the GA genotype of Ex2+37G>A in caspase-1 had increased risks of silicosis (adjusted ORs[95%CIs] = 2.40 [1.12–5.12] and 3.62 [1.63–8.02], respectively). Among subjects younger than 70 years old, those with the CC genotype of IVS8-7652A>C in Nalp3 had a lower risk of silicosis than those with other genotypes (adjusted OR[95%CI] = 0.24[0.06–0.88]). Among subjects aged 70 years and older, those with the CT genotype of Ex4-849C>T in Nalp3 and those with the GA genotype of Ex2+37G>A in caspase-1 had a higher risk of silicosis than those with other genotypes (adjusted ORs [95%CI] = 2.52[1.04–6.12] and 5.19[1.88–14.35], respectively). Among subjects with CDE greater than 120 mg/m3×year and among smokers, those with the GA genotype of Ex2+37G>A in caspase-1 had a higher risk of silicosis than those with other genotypes (adjusted ORs[95%CIs] = 26.37[3.35–207.39] and 3.47[1.40–8.64], respectively). Conclusions Genetic polymorphisms in Nalp3 and caspase-1 may be associated with individual susceptibility to silicosis, especially when the polymorphisms interact with age, CDE, or smoking status.
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Affiliation(s)
- Shaofan Weng
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
- Shenzhen Prevention and Treatment Center for Occupational Disease, Shenzhen, Guangdong, China
| | - Lihua Wang
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
- Shenzhen Baoan Center for Disease Control and Prevention, Shenzhen, Guangdong, China
| | - Yi Rong
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Yuewei Liu
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Xin Wang
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Hongyu Guan
- Daye Iron Mine Hospital, Wuhan Iron and Steel Corporation, Huangshi, Hubei, China
| | - Weihong Chen
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
- * E-mail:
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Liao CM, Wu BC, Cheng YH, You SH, Lin YJ, Hsieh NH. Ceramics manufacturing contributes to ambient silica air pollution and burden of lung disease. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2015; 22:15067-15079. [PMID: 26002365 DOI: 10.1007/s11356-015-4701-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 05/12/2015] [Indexed: 06/04/2023]
Abstract
Inhalation of silica (SiO2) in occupational exposures can cause pulmonary fibrosis (silicosis), lung function deficits, pulmonary inflammation, and lung cancer. Current risk assessment models, however, cannot fully explain the magnitude of silica-induced pulmonary disease risk. The purpose of this study was to assess human health risk exposed to airborne silica dust in Taiwan ceramics manufacturing. We conducted measurements to characterize workplace-specific airborne silica dust in tile and commodity ceramic factories and used physiologically based alveolar exposure model to estimate exposure dose. We constructed dose-response models for describing relationships between exposure dose and inflammatory responses, by which health risks among workers can be assessed. We found that silica contents were 0.22-33.04 % with mean concentration ranges of 0.11-5.48 and 0.46-1763.30 μg m(-3), respectively, in commodity and tile ceramic factories. We showed that granulation workers in tile ceramic factory had the highest total SiO2 lung burden (∼1000 mg) with cumulative SiO2 lung burden of ∼4 × 10(4) mg-year. The threshold estimates with an effect on human lung inflammation and fibrosis are 407.31 ± 277.10 (mean ± sd) and 505.91 ± 231.69 mg, respectively. For granulation workers, long-term exposure to airborne silica dust for 30-45 years was likely to pose severe adverse health risks of inflammation and fibrosis. We provide integrated assessment algorithms required to implement the analyses and maintain resulting concentration of silica dust at safety threshold level in the hope that they will stimulate further analyses and interpretation. We suggest that decision-makers take action to implement platforms for effective risk management to prevent the related long-term occupational disease in ceramics manufacturing.
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Affiliation(s)
- Chung-Min Liao
- Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei, 10617, Taiwan, Republic of China.
| | - Bo-Chun Wu
- Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei, 10617, Taiwan, Republic of China
| | - Yi-Hsien Cheng
- Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei, 10617, Taiwan, Republic of China
| | - Shu-Han You
- Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei, 10617, Taiwan, Republic of China
- National Environmental Health Research Center, National Health Research Institutes, Miaoli County, 35053, Taiwan, Republic of China
| | - Yi-Jun Lin
- Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei, 10617, Taiwan, Republic of China
| | - Nan-Hung Hsieh
- Institute of Labor, Occupational Safety and Health, Ministry of Labor, Executive Yuan, New Taipei City, 22143, Taiwan, Republic of China
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Cui X, Xing J, Liu Y, Zhou Y, Luo X, Zhang Z, Han W, Wu T, Chen W. COPD and levels of Hsp70 (HSPA1A) and Hsp27 (HSPB1) in plasma and lymphocytes among coal workers: a case-control study. Cell Stress Chaperones 2015; 20:473-81. [PMID: 25620081 PMCID: PMC4406932 DOI: 10.1007/s12192-015-0572-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Revised: 01/08/2015] [Accepted: 01/09/2015] [Indexed: 12/17/2022] Open
Abstract
This case-control study aimed to investigate whether the levels of Hsp70 (HSPA1A) and Hsp27 (HSPB1) in plasma and lymphocytes were associated with the risk of chronic obstructive pulmonary disease (COPD) among coal workers. A total of 76 COPD cases and 48 age-matched healthy controls from a group of coal workers were included. The case group consisted of 35 COPD patients whose condition was complicated with coal workers' pneumoconiosis (CWP) and 41 COPD patients without CWP. Heat shock proteins (Hsps) in plasma and lymphocytes were detected by ELISA and flow cytometry, respectively. Multiple logistic regression models were applied to estimate the association between Hsp levels and COPD risk. Our results showed that plasma Hsp70 and lymphocyte Hsp27 levels were significantly higher and plasma Hsp27 levels were significantly lower in COPD cases than in controls (p < 0.01). No significant differences in lymphocyte Hsp70 levels were found between COPD cases and the matched subjects. Higher plasma Hsp70 levels (odds ratio (OR) = 13.8, 95 % confidence interval (CI) = 5.7-33.5) and lower plasma Hsp27 levels (OR = 4.6, 95 % CI = 2.0-10.5) were significantly associated with an increased risk of COPD after adjusting for confounders. Higher lymphocyte Hsp27 levels were only associated with an increased risk of COPD with CWP (OR = 6.6, 95 % CI = 2.0-22.1) but not with an increased risk of COPD without CWP (OR = 3.0, 95 % CI = 0.9-8.9). Additionally, there were strong joint effects of different Hsps on COPD risk. These results showed that higher levels of plasma Hsp70 and lower levels of plasma Hsp27 might be associated with an increased risk of COPD among coal workers. They may have the potential to serve as monitoring markers for COPD in coal workers.
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Affiliation(s)
- Xiuqing Cui
- />Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health (Incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- />Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jingcai Xing
- />Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- />Department of Respiratory Diseases of the General Hospital of Xishan Coal & Power Group, Co. Ltd., Shanxi, 030053 China
| | - Yuewei Liu
- />Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health (Incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- />Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yun Zhou
- />Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health (Incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- />Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xin Luo
- />Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health (Incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- />Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zhihong Zhang
- />Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health (Incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- />Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Wenhui Han
- />Department of Respiratory Diseases of the General Hospital of Xishan Coal & Power Group, Co. Ltd., Shanxi, 030053 China
| | - Tangchun Wu
- />Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health (Incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- />Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Weihong Chen
- />Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, and State Key Laboratory of Environmental Health (Incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- />Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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Abstract
BACKGROUND The association between crystalline silica exposure and risk of heart disease mortality remains less clear. METHODS We investigated a cohort of 42,572 Chinese workers who were potentially exposed to crystalline silica and followed from 1960 to 2003. Cumulative silica exposure was estimated by linking a job-exposure matrix to each person's work history. Low-level silica exposure was defined as never having held a job with an exposure higher than 0.1 mg/m. We estimated hazard ratios (HRs) in exposure-response analyses using Cox proportional hazards model. RESULTS We identified 2846 deaths from heart disease during an average of 35 years follow-up. Positive exposure-response trends were observed for cumulative silica exposure associated with mortality from total heart disease (HRs for increasing quartiles of cumulative silica exposure compared with the unexposed group = 0.89, 1.09, 1.32, 2.10; P for linear trend < 0.001) and pulmonary heart disease (0.92, 1.39, 2.47, 5.46; P for linear trend < 0.001). These positive trends remained among workers with both high- and low-level silica exposure. There was also a positive trend for ischemic heart disease among workers with low-level exposure, with quartile HRs of 1.04, 1.13, 1.52, and 1.60 (P for linear trend < 0.001). CONCLUSION Low-level crystalline silica exposure was associated with increased mortality from heart disease, including pulmonary heart disease and ischemic heart disease, whereas high-level exposure mainly increased mortality from pulmonary heart disease. Current permissible exposure limits for crystalline silica in many countries may be insufficient to protect people from deaths due to heart disease.
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Radnoff D, Todor MS, Beach J. Exposure to crystalline silica at Alberta work sites: review of controls. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE 2015; 12:393-403. [PMID: 25625185 DOI: 10.1080/15459624.2015.1009987] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
From 2009 to 2013, Alberta Jobs, Skills, Training, and Labour (JSTL) conducted a project to evaluate exposure to crystalline silica and assess controls to protect workers. Information on exposure results has been previously reported; this article discusses the data collected on workplace controls. Information on work site controls was collected during exposure assessments consisting of qualitative information on controls in place and used by workers at the time of the assessments. Where there was sufficient data, the information was further analyzed to evaluate the impact of a particular control. While many types of controls were observed, they were not always effective or in use. The control available most often was respiratory protective equipment (RPE). Generally, when respirators were used, they were correctly selected for the level of measured exposure. However, not all workers who were potentially overexposed wore respirators at the time of the assessments. When the use of respirators was taken into account, about one-third of workers were still potentially exposed over the Alberta occupational exposure limit. The industries with the highest levels of exposure tended to be those with the most unprotected workers. Issues were identified with the use of improper work practices such as dry cleaning methods, lack of documented work procedures, poor housekeeping, and lack of training which may have contributed to worker exposure levels. There is a wide range in the efficacy of controls, particularly engineering controls. Most of the literature focuses on engineering controls; however administrative controls also play a role in reducing worker exposure. Data collected in this work indicated that simple changes to work procedures and behavior (such as improved housekeeping) may be effective, low-cost ways to reduce workplace exposure. More study is required to evaluate the impact and efficacy of administrative controls such as housekeeping and training. Employers must select and evaluate controls in the context of overall workplace health and safety programs and ensure that they are supported by supervision, good work practices. and training.
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Affiliation(s)
- Diane Radnoff
- a Safe, Fair and Healthy Workplaces, Alberta Jobs, Skills, Training and Labour , Edmonton , Alberta , Canada
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Radnoff D, Todor MS, Beach J. Occupational exposure to crystalline silica at Alberta work sites. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE 2014; 11:557-570. [PMID: 24479465 DOI: 10.1080/15459624.2014.887205] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Although crystalline silica has been recognized as a health hazard for many years, it is still encountered in many work environments. Numerous studies have revealed an association between exposure to respirable crystalline silica and the development of silicosis and other lung diseases including lung cancer. Alberta Jobs, Skills, Training and Labour conducted a project to evaluate exposure to crystalline silica at a total of 40 work sites across 13 industries. Total airborne respirable dust and respirable crystalline silica concentrations were quite variable, but there was a potential to exceed the Alberta Occupational Exposure Limit (OEL) of 0.025 mg/m(3) for respirable crystalline silica at many of the work sites evaluated. The industries with the highest potentials for overexposure occurred in sand and mineral processing (GM 0.090 mg/m(3)), followed by new commercial building construction (GM 0.055 mg/m(3)), aggregate mining and crushing (GM 0.048 mg/m(3)), abrasive blasting (GM 0.027 mg/m(3)), and demolition (GM 0.027 mg/m(3)). For worker occupations, geometric mean exposure ranged from 0.105 mg/m(3) (brick layer/mason/concrete cutting) to 0.008 mg/m(3) (dispatcher/shipping, administration). Potential for GM exposure exceeding the OEL was identified in a number of occupations where it was not expected, such as electricians, carpenters and painters. These exposures were generally related to the specific task the worker was doing, or arose from incidental exposure from other activities at the work site. The results indicate that where there is a potential for activities producing airborne respirable crystalline silica, it is critical that the employer include all worker occupations at the work site in their hazard assessment. There appears to be a relationship between airborne total respirable dust concentration and total respirable dust concentrations, but further study is require to fully characterize this relationship. If this relationship holds true, it may provide a useful hazard assessment tool for employers by which the potential for exposure to airborne respirable silica at the work site can be more easily estimated.
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Affiliation(s)
- Diane Radnoff
- a Jobs, Skills, Training and Labour, Safe , Fair and Healthy Workplaces Edmonton , Alberta , Canada
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Verma DK, Rajhans GS, Malik OP, des Tombe K. Respirable dust and respirable silica exposure in Ontario gold mines. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE 2014; 11:111-116. [PMID: 24369933 DOI: 10.1080/15459624.2013.843784] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A comprehensive survey of respirable dust and respirable silica in Ontario gold mines was conducted by the Ontario Ministry of Labor during 1978-1979. The aim was to assess the feasibility of introducing gravimetric sampling to replace the assessment method which used konimeters, a device which gave results in terms of number of particles per cubic centimeter (ppcc) of air. The study involved both laboratory and field assessments. The field assessment involved measurement of airborne respirable dust and respirable silica at all eight operating gold mines of the time. This article describes the details of the field assessment. A total of 288 long-term (7-8 hr) personal respirable dust air samples were collected from seven occupational categories in eight gold mines. The respirable silica (α-quartz) was determined by x-ray diffraction method. The results show that during 1978-1979, the industry wide mean respirable dust was about 1 mg/m(3), and the mean respirable silica was 0.08 mg/m(3.)The mean% silica in respirable dust was 7.5%. The data set would be useful in future epidemiological and health studies, as well as in assessment of workers' compensation claims for occupational diseases such as silicosis, chronic obstructive pulmonary disease (COPD), and autoimmune diseases such as renal disease and rheumatoid arthritis.
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Affiliation(s)
- Dave K Verma
- a Department of Family Medicine and Program in Occupational Health and Environmental Medicine, McMaster University , Hamilton , Ontario , Canada
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Liu Y, Steenland K, Rong Y, Hnizdo E, Huang X, Zhang H, Shi T, Sun Y, Wu T, Chen W. Exposure-response analysis and risk assessment for lung cancer in relationship to silica exposure: a 44-year cohort study of 34,018 workers. Am J Epidemiol 2013; 178:1424-33. [PMID: 24043436 DOI: 10.1093/aje/kwt139] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Crystalline silica has been classified as a human carcinogen by the International Agency for Research on Cancer (Lyon, France); however, few previous studies have provided quantitative data on silica exposure, silicosis, and/or smoking. We investigated a cohort in China (in 1960-2003) of 34,018 workers without exposure to carcinogenic confounders. Cumulative silica exposure was estimated by linking a job-exposure matrix to work history. Cox proportional hazards model was used to conduct exposure-response analysis and risk assessment. During a mean 34.5-year follow-up, 546 lung cancer deaths were identified. Categorical analyses by quartiles of cumulative silica exposure (using a 25-year lag) yielded hazard ratios of 1.26, 1.54, 1.68, and 1.70, respectively, compared with the unexposed group. Monotonic exposure-response trends were observed among nonsilicotics (P for trend < 0.001). Analyses using splines showed similar trends. The joint effect of silica and smoking was more than additive and close to multiplicative. For workers exposed from ages 20 to 65 years at 0.1 mg/m(3) of silica exposure, the estimated excess lifetime risk (through age 75 years) was 0.51%. These findings confirm silica as a human carcinogen and suggest that current exposure limits in many countries might be insufficient to protect workers from lung cancer. They also indicate that smoking cessation could help reduce lung cancer risk for silica-exposed individuals.
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Mossman BT, Glenn RE. Bioreactivity of the crystalline silica polymorphs, quartz and cristobalite, and implications for occupational exposure limits (OELs). Crit Rev Toxicol 2013; 43:632-60. [PMID: 23863112 DOI: 10.3109/10408444.2013.818617] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Silica or silicon dioxides (SiO₂) are naturally occurring substances that comprise the vast majority of the earth's crust. Because of their prevalence and commercial applications, they have been widely studied for their potential to induce pulmonary fibrosis and other disorders. Historically, the focus in the workplace has been on the development of inflammation and fibrotic lung disease, the basis for promulgating workplace standards to protect workers. Crystalline silica (CS) polymorphs, predominantly quartz and cristobalite, are used in industry but are different in their mineralogy, chemistry, surface features, size dimensions and association with other elements naturally and during industrial applications. Epidemiologic, clinical and experimental studies in the literature historically have predominantly focused on quartz polymorphs. Thus, in this review, we summarize past scientific evaluations and recent peer-reviewed literature with an emphasis on cristobalite, in an attempt to determine whether quartz and cristobalite polymorphs differ in their health effects, toxicity and other properties that may dictate the need for various standards of protection in the workplace. In addition to current epidemiological and clinical reports, we review in vivo studies in rodents as well as cell culture studies that shed light on mechanisms intrinsic to the toxicity, altered cell responses and protective or defense mechanisms in response to these minerals. The medical and scientific literature indicates that the mechanisms of injury and potential causation of inflammation and fibrotic lung disease are similar for quartz and cristobalite. Our analysis of these data suggests similar occupational exposure limits (OELs) for these minerals in the workplace.
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Affiliation(s)
- Brooke T Mossman
- Department of Pathology, University of Vermont College of Medicine, Burlington, VT 05405-0068, USA.
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Park RM, Chen W. Silicosis exposure-response in a cohort of tin miners comparing alternate exposure metrics. Am J Ind Med 2013; 56:267-75. [PMID: 22996756 DOI: 10.1002/ajim.22115] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/10/2012] [Indexed: 11/09/2022]
Abstract
BACKGROUND.: The detailed lung radiographic response to silica exposure has not been described. In estimating the exposure-response relationship in silicosis with statistical models, the absence of baseline (unattributable) risk can disable relative-rate estimation or produce widely varying estimates. This obstructs identification of optimum exposure metrics and invalidates comparisons and meta-analyses, which assume a common background rate. METHODS.: A cohort of 3,000 Chinese tin miners with more than 1,000 cases of silicosis was analyzed for the period 1961-1994. Regular surveillance documented three stages of silicosis. To examine the exposure-response relationship, the intercept in relative-rate models was fixed to correspond to 1% of the observed silicosis rate. Exposure metrics for contributions in different time-windows were simultaneously evaluated, as were burden and cumulative burden metrics. RESULTS.: Silica exposures that most contributed to silicosis onset occurred in the period 5-10 years prior (excess annual rate per 10 mg-year/m(3) , ER = 0.158, 95% CI = 0.125-0.192, or 16% per year). During 10-20 year prior, the excess rate contribution was much smaller (ER = 0.048, 95% CI = 0.037-0.060) but larger again during 20-30 year prior to onset (ER = 0.112, 95% CI = 0.098-0.126). For advanced silicosis, all time periods contributed about equally to the rate of onset. CONCLUSIONS.: Reliable estimates of parameters were observed, demonstrating exposure contributions over time. Burden metrics with different half-lives suggested some reversibility for silicosis onset with a half-life of 20 years. Advanced silicosis was best predicted with a cumulative burden metric which was consistent with prior observations that previously deposited silica continues to cause pulmonary damage.
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Affiliation(s)
- Robert M Park
- Risk Evaluation Branch, National Institute for Occupational Safety and Health, Cincinnati, OH, USA.
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Xu H, Yang F, Sun Y, Yuan Y, Cheng H, Wei Z, Li S, Cheng T, Brann D, Wang R. A new antifibrotic target of Ac-SDKP: inhibition of myofibroblast differentiation in rat lung with silicosis. PLoS One 2012; 7:e40301. [PMID: 22802960 PMCID: PMC3389005 DOI: 10.1371/journal.pone.0040301] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 06/04/2012] [Indexed: 02/06/2023] Open
Abstract
Background Myofibroblast differentiation, characterized by α-smooth muscle actin (α-SMA) expression, is a key process in organ fibrosis, and is induced by TGF-β. Here we examined whether an anti-fibrotic agent, N-acetyl-seryl-aspartyl-lysylproline (Ac-SDKP), can regulate induction of TGF-β signaling and myofibroblast differentiation as a potential key component of its anti-fibrotic mechanism in vivo and in vitro. Methodology/Principal Findings Rat pulmonary fibroblasts were cultured in vitro and divided to 4 groups 1) control; 2) TGF-β1; 3) TGF-β1+ LY364947; 4) TGF-β1+Ac-SDKP. For in vivo studies, six groups of animals were utilized 1) control 4w; 2) silicotic 4w; 3) control 8w; 4) silicotic 8w; 5) Ac-SDKP post-treatment; 6)Ac-SDKP pre-treatment. SiO2 powders were douched in the trachea of rat to make the silicotic model. Myofibroblast differentiation was measured by examining expression of α-SMA, as well as expression of serum response factor (SRF), a key regulator of myofibroblast differentiation. The expressions of collagen, TGF-β1 and RAS signaling were also assessed. The results revealed that TGF-β1 strongly induced myofibroblast differentiation and collagen synthesis in vitro, and that pre-treatment with Ac-SDKP markedly attenuated myofibroblast activation, as well as induction of TGF-β1 and its receptor. Similar results were observed in vivo in the pathologically relevant rat model of silicosis. Ac-SDKP treatment in vivo strongly attenuated 1) silicosis-induced increased expressions of TGF-β1 and RAS signaling, 2) myofibroblast differentiation as indicated by a robust decrease of SRF and α-SMA-positive myofibroblast localization in siliconic nodules in the lung, 3) collagen deposition. Conclusion/Significance The results of the present study suggest a novel mechanism of action for Ac-SDKP’s beneficial effect in silicosis, which involves attenuation of TGF-β1 and its receptors, SRF and Ang II type 1 receptor (AT1) expression, collagen deposition and myofibroblast differentiation. The results further suggest that therapies targeting myofibroblast differentiation may have therapeutic efficacy in treatment of silicosis of the lung.
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Affiliation(s)
- Hong Xu
- Department of Pathology, Hebei Medical University, Shi Jiazhuang, China
| | - Fang Yang
- Department of Pathology, Hebei Medical University, Shi Jiazhuang, China
- Medical Research Center, Hebei United University, Tangshan, China
- * E-mail:
| | - Ying Sun
- Medical Research Center, Hebei United University, Tangshan, China
| | - Yuan Yuan
- Medical Research Center, Hebei United University, Tangshan, China
| | - Hua Cheng
- Medical Research Center, Hebei United University, Tangshan, China
| | - Zhongqiu Wei
- Medical Research Center, Hebei United University, Tangshan, China
| | - Shuyu Li
- Medical Research Center, Hebei United University, Tangshan, China
| | - Tan Cheng
- Department of Pathology, Hebei Medical University, Shi Jiazhuang, China
| | - Darrell Brann
- Institute of Molecular Medicine and Genetics, Georgia Health Sciences University, Augusta, Georgia, United States of America
| | - Ruimin Wang
- Medical Research Center, Hebei United University, Tangshan, China
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Chen W, Liu Y, Wang H, Hnizdo E, Sun Y, Su L, Zhang X, Weng S, Bochmann F, Hearl FJ, Chen J, Wu T. Long-term exposure to silica dust and risk of total and cause-specific mortality in Chinese workers: a cohort study. PLoS Med 2012; 9:e1001206. [PMID: 22529751 PMCID: PMC3328438 DOI: 10.1371/journal.pmed.1001206] [Citation(s) in RCA: 151] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Accepted: 03/09/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Human exposure to silica dust is very common in both working and living environments. However, the potential long-term health effects have not been well established across different exposure situations. METHODS AND FINDINGS We studied 74,040 workers who worked at 29 metal mines and pottery factories in China for 1 y or more between January 1, 1960, and December 31, 1974, with follow-up until December 31, 2003 (median follow-up of 33 y). We estimated the cumulative silica dust exposure (CDE) for each worker by linking work history to a job-exposure matrix. We calculated standardized mortality ratios for underlying causes of death based on Chinese national mortality rates. Hazard ratios (HRs) for selected causes of death associated with CDE were estimated using the Cox proportional hazards model. The population attributable risks were estimated based on the prevalence of workers with silica dust exposure and HRs. The number of deaths attributable to silica dust exposure among Chinese workers was then calculated using the population attributable risk and the national mortality rate. We observed 19,516 deaths during 2,306,428 person-years of follow-up. Mortality from all causes was higher among workers exposed to silica dust than among non-exposed workers (993 versus 551 per 100,000 person-years). We observed significant positive exposure-response relationships between CDE (measured in milligrams/cubic meter-years, i.e., the sum of silica dust concentrations multiplied by the years of silica exposure) and mortality from all causes (HR 1.026, 95% confidence interval 1.023-1.029), respiratory diseases (1.069, 1.064-1.074), respiratory tuberculosis (1.065, 1.059-1.071), and cardiovascular disease (1.031, 1.025-1.036). Significantly elevated standardized mortality ratios were observed for all causes (1.06, 95% confidence interval 1.01-1.11), ischemic heart disease (1.65, 1.35-1.99), and pneumoconiosis (11.01, 7.67-14.95) among workers exposed to respirable silica concentrations equal to or lower than 0.1 mg/m(3). After adjustment for potential confounders, including smoking, silica dust exposure accounted for 15.2% of all deaths in this study. We estimated that 4.2% of deaths (231,104 cases) among Chinese workers were attributable to silica dust exposure. The limitations of this study included a lack of data on dietary patterns and leisure time physical activity, possible underestimation of silica dust exposure for individuals who worked at the mines/factories before 1950, and a small number of deaths (4.3%) where the cause of death was based on oral reports from relatives. CONCLUSIONS Long-term silica dust exposure was associated with substantially increased mortality among Chinese workers. The increased risk was observed not only for deaths due to respiratory diseases and lung cancer, but also for deaths due to cardiovascular disease. Please see later in the article for the Editors' Summary.
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Affiliation(s)
- Weihong Chen
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
- Ministry of Education Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Yuewei Liu
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
- Ministry of Education Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Haijiao Wang
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Eva Hnizdo
- Division of Respiratory Disease Studies, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia, United States of America
| | - Yi Sun
- Department of Applied Epidemiology, Institute for Occupational Safety and Health, German Social Accident Insurance (IFA), Sankt Augustin, Germany
| | - Liangping Su
- Daye Iron Mine Hospital, Wuhan Iron and Steel Corporation, Huangshi, Hubei, China
| | | | - Shaofan Weng
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Frank Bochmann
- Department of Applied Epidemiology, Institute for Occupational Safety and Health, German Social Accident Insurance (IFA), Sankt Augustin, Germany
| | - Frank J. Hearl
- Division of Respiratory Disease Studies, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia, United States of America
| | - Jingqiong Chen
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Tangchun Wu
- Department of Occupational and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
- Ministry of Education Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
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Aghilinejad M, Naserbakht A, Naserbakht M, Attari G. Silicosis among Stone- Cutter Workers: A Cross-Sectional Study. TANAFFOS 2012; 11:38-41. [PMID: 25191413 PMCID: PMC4153193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2011] [Accepted: 01/25/2012] [Indexed: 11/06/2022]
Abstract
BACKGROUND Production process of most factory-made products is harmful to our health and environment. Silica is the most important stone used in stone cutting factories. Numerous researches have reported respiratory diseases due to the inhalation of these particles in various occupations. Silicosis is a disease with typical radiographic pattern caused as the result of inhalation of silica particles. According to the intensity of exposures and onset of initiation of clinical symptoms silicosis is classified into three groups of acute, chronic and accelerated forms. The present study evaluated silicosis among stone cutter workers. MATERIALS AND METHODS This cross sectional study was performed on stone cutter workers in Malayer city (Azandarian) between 2008 and 2009. Respiratory data of our study participants were collected with a respiratory questionnaire and performing spirometry tests and chest radiography. RESULTS Among our participants, 16 silicosis cases were diagnosed by radiographic changes. Among them, 10 workers had exposure for more than three years and 6 workers were smokers. Eleven workers had an abnormal radiographic pattern on their chest x-rays. Seven workers had obstructive and 4 workers had restrictive spirometric patterns. CONCLUSION Prevalence of silicosis was high among our understudy workers and preventive strategies are required to control it.
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Affiliation(s)
- Mashaallah Aghilinejad
- Department of Occupational Medicine, Faculty of Medicine, Tehran University of Medical Sciences (TUMS), Tehran, Iran,Occupational Medicine Research Center, Tehran University of Medical Sciences (TUMS), Tehran, Iran
| | - Ali Naserbakht
- Occupational Medicine Research Center, Tehran University of Medical Sciences (TUMS), Tehran, Iran
| | - Morteza Naserbakht
- Occupational Medicine Research Center, Tehran University of Medical Sciences (TUMS), Tehran, Iran
| | - Ghavamedin Attari
- Occupational Medicine Research Center, Tehran University of Medical Sciences (TUMS), Tehran, Iran,Occupational Hygienist, Tehran University of Medical Sciences (TUMS), Tehran, Iran
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Change of exposure response over time and long-term risk of silicosis among a cohort of Chinese pottery workers. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2011; 8:2923-36. [PMID: 21845166 PMCID: PMC3155337 DOI: 10.3390/ijerph8072923] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 07/06/2011] [Accepted: 07/06/2011] [Indexed: 01/09/2023]
Abstract
An analysis was conducted on a cohort of Chinese pottery workers to estimate the exposure-response relationship between respirable crystalline silica dust exposure and the incidence of radiographically diagnosed silicosis, and to estimate the long-term risk of developing silicosis until the age of 65. The cohort comprised 3,250 employees with a median follow-up duration of around 37 years. Incident cases of silicosis were identified via silicosis registries (Chinese X-ray stage I, similar to International Labor Organisation classification scheme profusion category 1/1). Individual exposure to respirable crystalline silica dust was estimated based on over 100,000 historical dust measurements. The association between dust exposure, incidence and long-time risk of silicosis was quantified by Poisson regression analysis adjusted for age and smoking. The risk of silicosis depended not only on the cumulative respirable crystalline silica dust exposures, but also on the time-dependent respirable crystalline silica dust exposure pattern (long-term average concentration, highest annual concentration ever experienced and time since first exposure). A long-term "excess" risk of silicosis of approximately 1.5/1,000 was estimated among workers with all annual respirable crystalline silica dust concentration estimates less than 0.1 mg/m(3), using the German measurement strategy. This study indicates the importance of proper consideration of exposure information in risk quantification in epidemiological studies.
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Different course of silicosis in four brothers of one family. Int J Occup Med Environ Health 2009; 22:51-7. [DOI: 10.2478/v10001-009-0004-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Scarselli A, Binazzi A, Marinaccio A. Occupational exposure to crystalline silica: estimating the number of workers potentially at high risk in Italy. Am J Ind Med 2008; 51:941-9. [PMID: 18651580 DOI: 10.1002/ajim.20619] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
BACKGROUND Occupational exposure to free silica is widespread in several economic sectors and is well known to cause silicosis. This study was designed to establish a database of enterprises and workers in industrial sectors involving silica exposure in Italy and to estimate the number of workers potentially at high risk of exposure. METHODS The industrial sectors at risk of silica exposure were identified by selecting the industrial sector that employed people who were compensated for silicosis in 2000-2004. The enterprises and the number of workers (blue-collar) potentially at risk of silica exposure were selected from the Italian database of workplaces. RESULTS The number of workers potentially at high risk of silica exposure, were 28,712. The most involved sectors were: construction, mining and quarrying, metal working, and manufacturing of non-metallic products. Among regions in Italy, some exposure-disease scenarios were cited in literature, particularly in Sardinia, Liguria, and Tuscany. CONCLUSIONS Establishing a database of industries related to silica dust exposure and identifying the number of workers potentially at high risk can be useful to reinforce preventive measures and to control exposure.
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Affiliation(s)
- Alberto Scarselli
- National Institute for Occupational Safety and Prevention (ISPESL), Occupational Medicine Department, Epidemiology Unit, Rome, Italy.
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Dahmann D, Taeger D, Kappler M, Büchte S, Morfeld P, Brüning T, Pesch B. Assessment of exposure in epidemiological studies: the example of silica dust. JOURNAL OF EXPOSURE SCIENCE & ENVIRONMENTAL EPIDEMIOLOGY 2008; 18:452-461. [PMID: 18059424 DOI: 10.1038/sj.jes.7500636] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2007] [Accepted: 09/28/2007] [Indexed: 05/25/2023]
Abstract
Exposure to crystalline silica ranks among the most frequent occupational exposures to an established human carcinogen. Health-based occupational exposure limits can only be derived from a reliable dose-response relationship. Although quartz dust seems to be a well-measurable agent, several uncertainties in the quantification of exposure to crystalline silica can bias the risk estimates in epidemiological studies. This review describes the silica-specific methodological issues in the assessment of exposure. The mineralogical forms of silica, the technologies applied to generate dust, protective measures, and co-existing carcinogens are important parameters to characterize the exposure condition of an occupational setting. Another methodological question concerns the measurement of the respirable dust fraction in the worker's breathing zone and the determination of the quartz content in that fraction. Personal devices have been increasingly employed over time, whereas norms for the measurement of respirable dust have been defined only recently. Several methods are available to analyse the content of crystalline silica in dust with limits of quantitation close to environmental exposure levels. For epidemiological studies, the quartz content has frequently not been measured but only calculated. To develop a silica-dust database for epidemiological purposes, historical dust concentrations sampled with different devices and measured as particle numbers have to be converted in a common exposure metric. For the development of a job-exposure matrix (JEM), missing historical data have to be estimated to complete the database over time. Unknown but frequently high-exposure levels of the past contribute largely to the cumulative exposure of a worker. Because the establishment of a JEM is crucial for risk estimates, sufficient information should be made accessible to allow an estimation of the uncertainties in the assessment of exposure to crystalline silica. The impressive number of silica dust measurements and the evaluation of methodological uncertainties allow recommendations for a best practice of exposure assessment for epidemiological studies.
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Affiliation(s)
- Dirk Dahmann
- Institut für Gefahrstoff-Forschung (IGF), Institut an der Ruhr-Universität Bochum, Bochum, Germany.
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Madl AK, Donovan EP, Gaffney SH, McKinley MA, Moody EC, Henshaw JL, Paustenbach DJ. State-of-the-science review of the occupational health hazards of crystalline silica in abrasive blasting operations and related requirements for respiratory protection. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 2008; 11:548-608. [PMID: 18584454 DOI: 10.1080/10937400801909135] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Excessive exposures to airborne crystalline silica have been known for over 100 years to pose a serious health hazard. Work practices and regulatory standards advanced as the knowledge of the hazards of crystalline silica evolved. This article presents a comprehensive historical examination of the literature on exposure, health effects, and personal protective equipment related to silica and abrasive blasting operations over the last century. In the early 1900s, increased death rates and prevalence of pulmonary disease were observed in industries that involved dusty operations. Studies of these occupational cohorts served as the basis for the first occupational exposure limits in the 1930s. Early exposure studies in foundries revealed that abrasive blasting operations were particularly hazardous and provided the basis for many of the engineering control and respiratory protection requirements that are still in place today. Studies involving abrasive blasters over the years revealed that engineering controls were often not completely effective at reducing airborne silica concentrations to a safe level; consequently, respiratory protection has always been an important component of protecting workers. During the last 15-20 yr, quantitative exposure-response modeling, experimental animal studies, and in vitro methods were used to better understand the relationship between exposure to silica and disease in the workplace. In light of Occupational Safety and Health Administration efforts to reexamine the protectiveness of the current permissible exposure limit (PEL) for crystalline silica and its focus on protecting workers who are known to still be exposed to silica in the workplace (including abrasive blasters), this state-of-the-science review of one of the most hazardous operations involving crystalline silica should provide useful background to employers, researchers, and regulators interested in the historical evolution of the recognized occupational health hazards of crystalline silica and abrasive blasting operations and the related requirements for respiratory protection.
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Affiliation(s)
- Amy K Madl
- ChemRisk, Inc., San Francisco, California 94105, USA.
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High Prevalence and Advanced Silicosis in Active Granite Workers: A Dose-Response Analysis Including FEV1. J Occup Environ Med 2008; 50:827-33. [DOI: 10.1097/jom.0b013e31816a9e77] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Verma DK, Ritchie AC, Muir DCF. Dust content of lungs and its relationships to pathology, radiology and occupational exposure in Ontario hardrock miners. Am J Ind Med 2008; 51:524-31. [PMID: 18459150 DOI: 10.1002/ajim.20589] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Autopsied lungs from 29 hard rock miners were investigated to determine the relationship of the dust content to pathology, radiology, and occupational exposure. METHODS Each lung was divided horizontally into three sections. Pathological and radiological studies and chemical analyses were carried out on samples from each section. The hilar lymph nodes were also studied chemically. The work history and smoking history were assessed. The occupational exposure to silica and total dust were estimated. The effect of smoking was examined, and the relationship between dust content of the lungs to that of the lymph nodes were also investigated. RESULTS There was a good agreement between radiologic and pathologic findings. Positive correlations were seen between hydroxyproline (as an index of fibrosis), silica dust, non-silica inorganic dust, radiographic category of pneumoconiosis and pathologic grade of silicosis. Smokers lost on average 7 years of life compared to non-smokers, but numbers were small and no adjustment was made. Silica appeared to be concentrated in lungs and lymph nodes compared to the estimates of silica concentration in the mining environment. Silica in the lymph nodes on average is 2.4-fold higher than in the lungs. CONCLUSIONS This study of autopsied hard rock miners lungs shows positive relationships between lung dust and hydroxyproline content, radiological and pathological findings.
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Affiliation(s)
- Dave K Verma
- Program in Occupational Health and Enviornmental Medicine, McMaster University, Hamilton, Ontario, Canada.
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Yang H, Yang L, Zhang J, Chen J. Natural course of silicosis in dust-exposed workers. ACTA ACUST UNITED AC 2008; 26:257-60. [PMID: 16850763 DOI: 10.1007/bf02895832] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
To provide a scientific basis for determining the health surveillance period of dust-exposed workers, data of a retrospective cohort study was re-analyzed with emphasis on natural course of silicosis. 33640 workers exposed to silica dust who were employed for at least 1 year from 1972 to 1974 in twenty Chinese mines or pottery factories were included as subjects, and were followed up till December 31, 1994. The cohort included subjects from 8 tungsten mines, 4 tin mines and 8 pottery factories. Our results showed that the mean latency of silicosis, for all the cases of the cohorts, was 22.9 +/- 9.8 y. 52.2 % of silicosis was diagnosed approximately 9.1 +/- 5.7 y after the dust exposure had ceased. The progression rates of silicosis from stage I to II and from stage II to III were 48.2 % and 18.5 %, and the duration was 4.1 +/- 0.2 and 6.8 +/- 0.2 y, respectively. The survival times of silicosis stage I , II and III, from the year of diagnosis to death, were 21.5, 15.8 and 6.8 years, respectively. There was 25 % of the silicosis patients whose survival time was beyond 33 y. The mean death age of all silicosis cases was 56.0 y. The death age increased to 65.6 y in the middle of 1990s. Among dust-exposed workers, subjects who became suspected case (0+ ) accounted for 15.0 %. 48.7 % of the suspected silicosis cases developed to silicosis, and the average year from the time of being suspected of the disease to the first stage of silicosis was 5.1 y. The natural characteristics, as mentioned above, varied with different mines and factories. We are led to conclude that silicosis is chronic in nature, but progress quickly. As a serious occupational disease it significantly reduces the life span of exposed workers. The study of its natural history is of importance for the development of health surveillance criteria for dust-exposed workers.
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Affiliation(s)
- Haibing Yang
- Department of Occupational Health and Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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Kant S, Gupta B. Role of lifestyle in the development of chronic obstructive pulmonary disease: a review. Lung India 2008; 25:95-101. [PMID: 20165658 PMCID: PMC2822328 DOI: 10.4103/0970-2113.59591] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Surya Kant
- Professor Dept. of Pulmonary Medicine, Chhtrapati Shahuji Maharaj Medical University (Erstwhile King George Medical University, Lucknow
| | - Barkha Gupta
- Research Scholar Dept. of Pulmonary Medicine, Chhtrapati Shahuji Maharaj Medical University (Erstwhile King George Medical University, Lucknow
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Tse LA, Li ZM, Wong TW, Fu ZM, Yu ITS. High prevalence of accelerated silicosis among gold miners in Jiangxi, China. Am J Ind Med 2007; 50:876-80. [PMID: 17948247 DOI: 10.1002/ajim.20510] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Accelerated silicosis has become uncommon in developed countries, whereas serious health threat still exists in small-scale mining in developing countries. This study was to investigate the prevalence and risk factors of accelerated silicosis among Chinese gold miners. METHODS A cross-sectional medical examination was conducted among 574 Chinese gold miners. All participants were male rock-drillers. The concentrations of total dust and quartz content were obtained from the government documentations. Descriptive data analyses were performed. RESULTS The prevalence of accelerated silicosis was 29.1% (95% CI: 24.8-33.4%, 167 cases) after an average of 5.6 years of dust exposure, and a history of tuberculosis seemed to increase the risk. The concentration of respirable silica dust was estimated to be 89.5 mg/m(3) (ranged: 70.2-108.8) in the underground goldmine, far exceeding the permissible exposure limits. CONCLUSIONS This study illustrates a serious health threat to small-scale goldmine in China and indicates an urgent need for environmental control and disease prevention.
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Affiliation(s)
- Lap Ah Tse
- Department of Community & Family Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China
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Fanizza C, Ursini CL, Paba E, Ciervo A, Di Francesco A, Maiello R, De Simone P, Cavallo D. Cytotoxicity and DNA-damage in human lung epithelial cells exposed to respirable α-quartz. Toxicol In Vitro 2007; 21:586-94. [PMID: 17257809 DOI: 10.1016/j.tiv.2006.12.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2006] [Revised: 12/06/2006] [Accepted: 12/10/2006] [Indexed: 12/01/2022]
Abstract
Occupational exposure to respirable crystalline silica is associated with the development of silicosis, lung cancer and airways diseases. In order to assess cytotoxic effects and direct-oxidative DNA damage induced by short-term exposure to different doses of respirable alpha-quartz (NIST SRM1878a), we conducted a study using A549 cells. The cells were exposed to alpha-quartz at 25, 50, 100 microg/ml for 4 h and analysed by scanning electron microscope (SEM) and LDH release assay for cytotoxic effect evaluation. Cells were also exposed to 10, 25, 50, 100 microg/ml of alpha-quartz for 2 h and 4 h and analysed by Fpg comet test to evaluate direct and oxidative DNA damage. SEM observations of treated cells showed bleb development at lower doses and alterations of microvilli morphology at the highest dose. A slight LDH release was found only at 100 microg/ml. Fpg comet test showed a dose-related oxidative DNA damage in cells exposed for 2 h to quartz. Cells exposed for 4h at the same concentrations showed a dose-related direct DNA damage and the presence of oxidative DNA damage at lower doses. The bleb induction on cell surface evidenced by SEM at lower doses correlates with the presence of oxidative DNA damage at 4 h. The cell surface modifications observed by SEM at 100 microg/ml indicate that high doses of quartz induce more evident cytotoxic effects confirmed by LDH analysis and correlate with the genotoxicity showed by comet assay.
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Affiliation(s)
- Carla Fanizza
- Department of Occupational Hygiene, ISPESL, National Institute for Occupational Safety and Prevention, Via Fontana Candida 1, 00040 Monteporzio Catone, Rome, Italy.
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Abstract
Rapidly industrializing India is described by the International Monetary Fund as a young, disciplined, and vibrant economy with a projected growth of 6.7% for 2005. The total workforce of 397 million has only 7% of workers employed in the organized sector with construction, where asbestos exposure is prevalent, employing 4.4%. The domestic production of asbestos declined from 20,111 tons in 1998-1999 to 14,340 tons in 2002-2003. The imports from Russia and Canada increased from 61,474 tons in 1997-1998 to 97,884 tons in 2001-2002. The production of asbestos cement products went up from 0.68 million tons in 1993-1994 to 1.38 million tons in 2002-2003. The asbestos industry has been delicensed since March 2003. The number of asbestos-based units stood at 32, with the western state of Maharashtra having the largest number. According to official figures, the industry employs 8000 workers. The occupational exposure standard is still 2 fibers/mL, worse still, mesothelioma is not recognized as an occupational disease. The latest cancer registry data have no information on mesothelioma. The health and safety legislation does not cover 93% of workers in the unorganized sector where asbestos exposures are extremely high. Workers remain uninformed and untrained in dealing with asbestos exposure. Enforcement agencies are not fully conscious of the risks of asbestos exposure. Industrial hygiene assessment is seldom carried out and pathologists do not receive training in identifying mesothelioma histopathologically. The lack of political will and powerful influence of the asbestos industry are pushing India toward a disaster of unimaginable proportion.
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Affiliation(s)
- Tushar Kant Joshi
- Centre for Occupational and Environmental Health, Lok Nayak Hospital, New Delhi 110002, India.
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Abstract
BACKGROUND Crystalline silica is well known to cause silicosis and other diseases. Exposure is common in the mining industry and consequently, the US Mine Safety and Health Administration (MSHA) evaluates miners exposure to silica to determine compliance with its exposure limit. METHODS MSHA exposure measurements were obtained for the 5-year period from 1998 to 2002 and average exposure was calculated classified by occupation and by mine. Evaluation criteria were whether average values exceeded MSHA's permissible exposure limit or the limit recommended by the National Institute for Occupational Safety and Health (NIOSH), whether there was a risk of exposure to freshly fractured silica, and whether there was a risk of a high rate of exposure to silica. RESULTS Miners in certain jobs are exposed to silica above permissible and recommended exposure limits. Some miners may also be exposed at a high rate or to freshly fractured silica. CONCLUSIONS Known dust control methods should be implemented and regular medical surveillance should be provided.
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Affiliation(s)
- James L Weeks
- Advanced Technologies & Laboratories International, Germantown, Maryland 20854, USA.
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Chen W, Yang J, Chen J, Bruch J. Exposures to silica mixed dust and cohort mortality study in tin mines: exposure-response analysis and risk assessment of lung cancer. Am J Ind Med 2006; 49:67-76. [PMID: 16362950 DOI: 10.1002/ajim.20248] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Mineral dusts that contain crystalline silica have been associated directly or indirectly with the development of pneumoconiosis or silicosis, non-malignant respiratory diseases, lung cancer, and other diseases. The health impacts on workers with silica mixed dust exposure in tin mines and dose-response relationships between cumulative dust exposure and the mortality from lung cancer are investigated. METHODS A cohort of 7,837 workers registered in the employment records in 4 Chinese tin mines between 1972 and 1974 was identified for this study and the mortality follow-up was traced through 1994. Of the cohort, the cause of death was ascertained for 1,061 (97%) of the 1,094 deceased workers. Standardized mortality ratios (SMRs) were calculated for all workers, non-exposed workers, and dust-exposed workers with different exposure levels, silicotics, and non-silicotics based on Chinese national rates. RESULTS The mortality from all causes in four tin mines was nearly the same as the national mortality. Malignant neoplasm, cerebrovascular disease, and cardiovascular disease accounted for 68.6% of all deaths. Mortality excess from lung cancer, liver cancer, all malignant diseases, and non-malignant respiratory diseases was observed among dust-exposed workers; a 50-fold excess of pneumoconiosis was observed. There was an upward trend for SMRs of lung cancer was noted from no exposure to low, medium, and high exposure levels (SMRs=1.29, 2.65, 2.66, 3.33). The shape of the exposure-response curve for risk of lung cancer at high exposure levels was inconsistent in these four mines. CONCLUSIONS The findings indicated a positive dose-response relation between exposure to cumulative dust and the mortality of lung cancer. High arsenic content in dust particles, together with crystalline silica, may play an important role in causing increased mortality from lung cancer.
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Affiliation(s)
- Weihong Chen
- Department of Occupational and Environmental Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
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Collins JF, Salmon AG, Brown JP, Marty MA, Alexeeff GV. Development of a chronic inhalation reference level for respirable crystalline silica. Regul Toxicol Pharmacol 2005; 43:292-300. [PMID: 16185799 DOI: 10.1016/j.yrtph.2005.08.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2005] [Indexed: 01/08/2023]
Abstract
Chronic inhalation exposure of workers to crystalline silica can result in silicosis. The general public can also be exposed to lower levels of crystalline silica from quarries, sand blasting, and entrained fines particles from surface soil. We have derived an inhalation chronic reference exposure level for silica, a level below which no adverse effects due to prolonged exposure would be expected in the general public. Incidence of silicosis and silica exposure data from a cohort of 2235 white South African gold miners yielded a reference level of 3 microg/m3) for respirable silica (particle size as defined occupationally) using a benchmark concentration approach. Data from cohorts of American gold miners, Chinese tin miners, diatomaceous earth workers, and black South African gold miners yielded similar results with a range of 3-10 microg/m3. Strengths of the chronic reference exposure level include the availability of several large long-term studies of inhalation in workers at varying exposure concentrations, adequate histopathological and radiologic analysis, adequate follow-up of exposed workers, a dose-response effect in several studies, observation of a No Observed Adverse Effect Level in the key study, and the power of the key study to detect a small effect. Uncertainties include the general underestimation of silicosis by radiography alone and the uncertainties in exposure estimation.
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Affiliation(s)
- James F Collins
- Air Toxicology and Epidemiology Branch, Office of Environmental Health Hazard Assessment, California Environmental Protection Agency, 1515 Clay Street, 16th Floor, Oakland, CA 94612, USA.
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Harrison J, Chen JQ, Miller W, Chen W, Hnizdo E, Lu J, Chisholm W, Keane M, Gao P, Wallace W. Risk of silicosis in cohorts of Chinese tin and tungsten miners and pottery workers (II): Workplace-specific silica particle surface composition. Am J Ind Med 2005; 48:10-5. [PMID: 15940714 DOI: 10.1002/ajim.20175] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND It is hypothesized that surface occlusion by alumino-silicate affects the toxic activity of silica particles in respirable dust. In conjunction with an epidemiological investigation of silicosis disease risk in Chinese tin and tungsten mine and pottery workplaces, we analyzed respirable silica dusts using a multiple-voltage scanning electron microscopy-energy dispersive X-ray spectroscopy (MVSEM-EDS). METHODS Forty-seven samples of respirable sized dust were collected on filters from 13 worksites and were analyzed by MVSEM-EDS using high (20 keV) and low (5 keV) electron beam accelerating voltages. Changes in the silicon-to-aluminum X-ray line intensity ratio between the two voltages are compared particle-by-particle with the 90th percentile value of the same measurements for a ground glass homogeneous control sample. This provides an index that distinguishes a silica particle that is homogeneously aluminum-contaminated from a clay-coated silica particle. RESULTS The average sample percentages of respirable-sized silica particles alumino-silicate occlusion were: 45% for potteries, 18% for tin mines, and 13% for tungsten mines. The difference between the pottery and the metal mine worksites accounted for one third of an overall chi-square statistic for differences in change in measured silicon fraction between the samples. CONCLUSION The companion epidemiological study found lower silicosis risk per unit cumulative respirable silica dust exposure for pottery workers compared to metal miners. Using these surface analysis results resolves differences in risk when exposure is normalized to cumulative respirable surface-available silica dust.
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Affiliation(s)
- J Harrison
- Health Effects Laboratory Division, US National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV 26505, USA
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Steenland K. One agent, many diseases: exposure-response data and comparative risks of different outcomes following silica exposure. Am J Ind Med 2005; 48:16-23. [PMID: 15940719 DOI: 10.1002/ajim.20181] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
BACKGROUND Evidence in recent years indicates that silica causes lung cancer, and probably renal disease, in addition to its well-known relationship to silicosis. There is also suggestive evidence that silica can cause arthritis and other auto-immune diseases. Silica has, therefore, joined a handful of other toxic exposures such as tobacco smoke, dioxin, and asbestos which cause multiple serious diseases. METHODS The available exposure-response data for silica and silicosis, lung cancer, and renal disease are reviewed. We compare the corresponding excess risks (or absolute risks in the case of silicosis) of death or disease incidence by age 75 for these three diseases, subsequent to a lifetime (45 years) of exposure to silica at current US standard (0.1 mg/m(3) respirable crystalline silica). RESULTS The absolute risk of silicosis, as defined by small opacities greater than or equal to ILO classification 1/1 on an X-ray, ranges from 47% to 77% in three cohort studies with adequate follow-up after employment. The absolute risk of death from silicosis is estimated at 1.9% (0.8%-2.9%), based on a pooled analysis of six cohort studies. The excess risk of lung cancer death, assuming US male background rates, is 1.7% (0.2%-3.6%), based on a pooled analysis of ten cohort studies. The excess risk of end-stage renal disease (assuming male background rates) is 5.1% (2.2%-7.3%), based on a single cohort. The excess risk of death from renal disease is estimated to be 1.8% (0.8%-9.7%), based on a pooled analysis of three cohorts. CONCLUSIONS Keeping in mind that the usual OSHA acceptable excess risk of serious disease or death for workers is 0.1%, it is clear that the current standard is far from sufficiently protective of workers' health. Perhaps surprisingly, kidney disease emerges as perhaps a higher risk than either mortality from silicosis or lung cancer, although the data are based on fewer studies.
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Affiliation(s)
- Kyle Steenland
- Rollins School of Public Health, Emory University, 1518 Clifton Road, Atlanta, GA 30322, USA.
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