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Occupational Exposure to Crystalline Silica at Alberta Work Sites
Journal of Occupational and Environmental Hygiene
Abstract
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 over-exposure 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 at levels 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 respirable quartz 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.
... Campionamenti ambientali e personali DRX -- (18) 0.28 -4.9 (19) 0.28 -0.94 (20) 0.005 -0.018 Note: (1) Per tutte le attività che coinvolgono arenaria. (2) Per compiti che prevedono la manipolazione di calcare. ...
... alla lavorazione di granito. (18) Monitoraggio dei lavoratori addetti al taglio e finitura a secco di piani in quarzo-resina. (19) Monitoraggio dei lavoratori addetti ad altre mansioni. ...
... Altro interessante confronto riguarda lo studio di Radnoff del 2014 (18) sulla valutazione dell'esposizione professionale a SCL in 40 siti in Alberta appartenenti a 13 diversi settori produttivi. I dati sono riportati in tabella 6. È evidente una certa discordanza. ...
Introduzione: L’esposizione a polveri respirabili contenenti silice libera cristallina è di grande interesse per le gravi patologie polmonari conseguenti. Metodi: Nel periodo 1986-2019 sono stati raccolti 3611 dati di esposizione a quarzo-alfa provenienti da aziende del centro Italia. I dati sono stati suddivisi e analizzati in base al sistema di campionamento (Ciclone Dorr Oliver, CIP 10-R, Ciclone GS3, Selettore SKC in plastica, Ciclone Higgins-Dewell e Ciclone Lippmann) e al codice ATECO (codice di attività economica, acronimo italiano, usato per classificare le imprese quando si interfacciano con le pubbliche istituzioni) dell’azienda di provenienza. Per ogni codice ATECO è stata effettuata la suddivisione in base alla tipologia di campionamento (personale o statico) e sono state calcolate le statistiche descrittive dei dati. Risultati: Dall’analisi complessiva dei campionamenti personali si evince che l’8,8% dei dati supera 0,1 mg/m3, il 19,6% supera 0,05 mg/m3 e il 33,8% supera 0,025 mg/m3, valori limite rispettivamente fissato dalla Direttiva UE 2019/130, suggerito dallo SCOEL e pubblicato da ACGIH. I codici ATECO con la più elevata esposizione (media geometrica rispettivamente 0,069 e 0,067 mg/m3) sono il 23.31.00 (fabbricazione di piastrelle in ceramica per pavimenti e rivestimenti) e il 23.42.00 (fabbricazione di articoli sanitari in ceramica), mentre l’esposizione più bassa si riscontra nel 81.29.91 (pulizia e lavaggio di aree pubbliche, rimozione di neve e ghiaccio incluso lo spargimento di sabbia) (media geometrica 0,002 mg/m3). Discussione: Nonostante una generale riduzione nel tempo, sono ancora molti i settori in cui si riscontrano superamenti degli attuali limiti di esposizione professionale; soprattutto in tali settori è necessario implementare le misure per valutare compiutamente l’esposizione dei lavoratori.
... RCS, on the other hand, is a fibrogenic material found in nature, exposure to which causes interstitial pulmonary fibrosis known as silicosis [13]. RCS particles are respirable when they are less than 5 microns in diameter and when inhaled are capable of reaching the distal airways and alveoli and can scar the lungs [14,15]. Exposure to RCS has also been associated with COPD, lung cancer, airway obstruction, and renal disease [16]. ...
... In 1974 the United States National Institute of Occupational Safety and Health (NIOSH) recommended an ES of 0.05 mg/m 3 for RCS, while the American Conference of Governmental Industrial Hygienists (ACGIH) adopted a threshold limit value (TLV) of 0.025 mg/m 3 in 2006 [15]. In Alberta Canada, 0.025 mg/m 3 was adopted in 2009 as the ES for RCS [15]. ...
... In 1974 the United States National Institute of Occupational Safety and Health (NIOSH) recommended an ES of 0.05 mg/m 3 for RCS, while the American Conference of Governmental Industrial Hygienists (ACGIH) adopted a threshold limit value (TLV) of 0.025 mg/m 3 in 2006 [15]. In Alberta Canada, 0.025 mg/m 3 was adopted in 2009 as the ES for RCS [15]. ...
Background
Exposure to respirable dust (RES) and respirable crystalline silica (RCS) is common in mining operations and is associated with health effects such as pneumoconiosis, chronic obstructive pulmonary disease (COPD), interstitial pulmonary fibrosis, silicosis, lung cancer, and renal disease.
Methods
This study used industry occupational exposure data for respirable dust from two surface lithium mines in Western Australia for the period between 2017 and 2023. A total of 1122 samples were collected in workgroups across four departments - administration and support, mining, crushing and processing, and maintenance.
Results
The study found that the overall RES concentration did not exceed the exposure standard. However, Crusher Dry/Wet Plant Personnel (0.558 mg/m³) and Workshop Boilermakers (0.842 mg/m³) recorded elevated exposure to RES. The highest mean exposures for RCS over the seven-year study period were measured for Management Administration & Technical (0.068 mg/m³), followed by Crusher Dry/Wet Plant Personnel (0.042 mg/m³), exceeding the ES. Maximum results for both RES (15.00 mg/m³) and RCS (2.50 mg/m³) indicated exceedances.
Conclusion
The study demonstrated a decline in exposure to RES over the seven years of study from 0.472 mg/m³ to 0.151 mg/m³, with a slight increase in 2019 and 2022. A decline in the concentration of RCS was observed between 2019 -2021, followed by an increase after 2021. The mean concentration of RCS exceeded the exposure standard in 2023. Based on the study results and the established adverse health effects associated with exposure to silica, various control measuresto protect workers from RCS exposure should be considered.
... In general, exposure concentrations of respirable crystalline silica have declined over the past 50 years (Yassin et al., 2005;Creely et al., 2007;Peters et al., 2011;Zilaout et al., 2020), but high concentrations are still reported in foundries (Andersson et al., 2009;Radnoff et al., 2014), the stone and brick sector (Healy et al., 2014;Radnoff et al., 2014;Baldwin et al., 2019), and in construction (Radnoff et al., 2014;Bello et al., 2019). It was estimated that 5.3 million workers in Europe were potentially occupationally exposed to respirable crystalline silica in 2006, of which 75% were employed in construction (IOM, 2011). ...
... In general, exposure concentrations of respirable crystalline silica have declined over the past 50 years (Yassin et al., 2005;Creely et al., 2007;Peters et al., 2011;Zilaout et al., 2020), but high concentrations are still reported in foundries (Andersson et al., 2009;Radnoff et al., 2014), the stone and brick sector (Healy et al., 2014;Radnoff et al., 2014;Baldwin et al., 2019), and in construction (Radnoff et al., 2014;Bello et al., 2019). It was estimated that 5.3 million workers in Europe were potentially occupationally exposed to respirable crystalline silica in 2006, of which 75% were employed in construction (IOM, 2011). ...
... In general, exposure concentrations of respirable crystalline silica have declined over the past 50 years (Yassin et al., 2005;Creely et al., 2007;Peters et al., 2011;Zilaout et al., 2020), but high concentrations are still reported in foundries (Andersson et al., 2009;Radnoff et al., 2014), the stone and brick sector (Healy et al., 2014;Radnoff et al., 2014;Baldwin et al., 2019), and in construction (Radnoff et al., 2014;Bello et al., 2019). It was estimated that 5.3 million workers in Europe were potentially occupationally exposed to respirable crystalline silica in 2006, of which 75% were employed in construction (IOM, 2011). ...
Background:
High concentrations of respirable quartz have been reported from workers in construction, foundries, and quarries. Current exposure concentrations in prevalent but presumably lower exposed occupations have been less examined. We aimed to quantify current exposure concentrations of respirable dust and quartz across prevalent occupations and to identify determinants of respirable quartz exposure across these occupations.
Methods:
One hundred and eighty-nine full-shift personal samples of respirable dust of workers within 11 occupations in Denmark were sampled during 2018. Respirable dust was determined gravimetrically and analysed for quartz content with infrared spectrometry. Determinants for respirable quartz exposure, i.e. use of power tools, outdoor or indoor location, and percentage of quartz in respirable dust, were analysed in linear mixed effect models.
Results:
The overall geometric means (geometric standard deviations) for respirable dust and quartz were 216 µg m-3 (4.42) and 16 µg m-3 (4.07), respectively. The highest quartz concentrations were observed among stone cutters and carvers [93 µg m-3 (3.47)], and metal melters and casters [61 µg m-3 (1.71)]. Use of power tools increased exposure concentrations of quartz by a factor of 3.5. Occupations explained 27%, companies within occupations 28%, and differences between workers within companies within occupations 14% of the variability in quartz concentrations. Thirty percent was due to day-to-day variability in exposure concentrations. In total, 19% of the variation in quartz concentration could be explained by type of tool, indoor/outdoor location, and percentage of quartz in respirable dust.
Conclusion:
Current exposure concentrations are generally low, but some occupations in this study had average exposure concentrations to respirable quartz above the ACGIH threshold limit value of 25 µg m-3. Preventive measures to lower excess risk of quartz-related diseases among these workers are still needed. In terms of preventive strategies, use of power tools and quartz content of used materials were identified as main determinants of exposure. Lowering of exposures will be most efficient when focussed on these major determinants, e.g. tool dust control with water, dust extraction, and use of low quartz content materials.
... Previous studies have reported the concentration of RCS in construction sites based on typical occupations of tunnel construction worker [4][5][6], cement mason and concrete finisher [5][6][7][8], and building demolition [5,[9][10][11]. The concentration of DEE in construction sites were reported for tunnel [4,12,13] and highway [14]. ...
... Previous studies have reported the concentration of RCS in construction sites based on typical occupations of tunnel construction worker [4][5][6], cement mason and concrete finisher [5][6][7][8], and building demolition [5,[9][10][11]. The concentration of DEE in construction sites were reported for tunnel [4,12,13] and highway [14]. ...
... Previous studies have reported the concentration of RCS in construction sites based on typical occupations of tunnel construction worker [4][5][6], cement mason and concrete finisher [5][6][7][8], and building demolition [5,[9][10][11]. The concentration of DEE in construction sites were reported for tunnel [4,12,13] and highway [14]. Although, the concentration levels and workers' exposure to contaminants in tunnel and highway construction have been reported by many researchers, its evaluation for excavation works in top-down constructions is still missing. ...
Enclosed underground excavation worksite has an environment with poor ventilation and exposure to hazardous substances from diesel engine exhaust and construction materials. The objective of this study was to evaluate the exposure level of elemental carbon (EC), organic carbon (OC), total carbon (TC), polycyclic aromatic hydrocarbons (PAHs), dust and crystalline silica (CS) during underground excavation work for top down construction buildings. Active local air sampling for EC, OC, and TC (n = 105), PAHs (n = 50), dust (n = 34) and CS (n = 34) was conducted from inside and outside the excavator at underground excavation workshop in four different construction sites. EC, OC, TC and CS were sampled with each respirable and total particulates. EC, OC, and TC were collected on quartz-filter and analyzed using the thermal optical transmittance method. PAHs was collected on polytetrafluorethylene filter with XAD-2 and analyzed using liquid chromatography with fluorescence detector. CS and particulates were collected on poly vinyl chloride filter and analyzed using fourier-transform infrared spectroscopy. The geometric mean of respirable EC, OC, TC, total PAHs, respirable dust and respirable CS were 8.69 μg/m³, 34.32 μg/m³, 44.96 μg/m³, 6.818 μg/m³ 0.13 mg/m³ and 0.02 mg/m³ from inside the excavator and 33.20 μg/m³, 46.53 μg/m³, 78.21 μg/m³, 3.934 μg/m³, 0.9 mg/m³ and 0.08 mg/m³ from outside the excavator (underground excavation workshop), respectively. The EC and RCS concentration from outside the excavator is significantly higher than that of inside the excavator (p<0.01). The worksite with rock ground, higher vehicle density, blasting and enclosed environments had higher exposure to EC than other sites (p<0.05). There was no significant difference of EC concentration between total and respirable particulates. In top down construction sites, EC concentrations during underground excavation work exceeded recommended exposure limits as 20 μg/m³, accounted for about 50% of the total sample, and the level of concentration of RCS exceeded 1.5 times of occupational exposure limit, 0.05 mg/m³. Efforts are needed to minimize exposure to diesel engine exhaust and silica in underground excavation sites. Management of diesel engine vehicle, supply of fresh air and ventilation and introducing water facilities to create wet environment in underground worksites are strongly suggested.
... Descriptive statistical analyses were used to calculate the arithmetic means (AMs) and geometric means (GMs) of RCS exposure levels in addition to 95% confidence intervals (CIs), geometric standard deviations (GSDs), and exceedance fractions of the six industries, 18 occupations, and four area samples in units of μg/m 3 . Exposure severities were calculated by dividing the time-weighted average (TWA) exposure by the OEL to facilitate the comparison of RCS exposures for each industry, occupation, and area concerning the Alberta OEL (Esswein et al., 2013;Radnoff et al., 2014). ...
... Exposure values of RCS in the S&G industry (GM = 38 μg/m 3 ) found in our study are similar to the concentrations reported by Sanderson et al. (2000) and Rando et al. (2001) in the US sand workers who found the values to be between 26 μg/m 3 and 42 μg/m 3 . However, the concentrations in our study are about half the values reported in previous studies in the sand industry by Brown and Rushton (2005) in the United Kingdom and Radnoff et al. (2014) in Canada, who found the exposures value to be 90 μg/m 3 . The RCS values found in this study for the A&P industry (18 g/m 3 ) were found to be higher than those reported by Hammond et al. (2016) in the United States, who found the RCS values to be between 4 μg/m 3 and 9 μg/m 3 among workers during asphalt pavement milling. ...
Occupational exposure to respirable crystalline silica (RCS) is common for several occupations in construction, not only because of its presence in many handling materials but also in processes such as grinding and sawing. This study investigated workplace exposure to RCS as quartz in industries and occupations within road construction in Alberta through the RCS monitoring database provided by the Alberta Roadbuilders and Heavy Construction Association (ARHCA) between 2007 and 2016. Descriptive statistics were calculated for exposure-related variables, and mixed model analysis was performed to determine factors affecting the exposure levels. Results showed that the highest exposed workers were in the sand and gravel industry (GM = 45 μg/m ³ ). For worker occupations, geometric means ranged from 78 μg/m ³ for crusher operators to 10 μg/m ³ for concrete truck operators. The maximum exposure severity was 33.3 times the occupational exposure limit (OEL) for the sand and gravel and 31 times the OEL for tower operators. The results also showed the effect of seasonal variability on RCS exposure levels. The heterogeneous exposure results indicated significant room for improvement and that controls should focus more on the activity performed than the occupation to lower exposure to RCS levels in industries.
... Industrial aerosols occur in workplace air when metal items are processed mechanically (when moldings are purified, polished, and ground), or due to thermal processes or sublimation of solid substances (melting, welding, etc.). Depending on their chemical structure, __________________________ industrial aerosols can produce fibrogenic, irritating, toxic, allergenic, carcinogenic, and ionizing effects on the body 1 . Workers employed at metallurgic production or civil engineering enterprises are primarily exposed to aerosols with fibrogenic effects. ...
... Health outcomes that may result from occupational exposure to industrial aerosols are given a lot of attention by experts in the field and studies usually concentrate on examining pathogenetic mechanisms of interaction between aerosol particles in workplace air and lung tissue cells [1]. Silicon-containing welding aerosols have significant capacity to activate the monocytic-macrophage system of the body. ...
Our research goal was to estimate neopterin level in blood serum of workers occupationally exposed to industrial aerosols with predominantly fibrogenic effects; to establish a relationship between this level and workers’ age, working experience in hazardous working conditions, spirometric parameters and the level of C-reactive protein. We also aimed to assess neopterin as a possible biomarker showing risks of the developing inflammatory process in the bronchi and lungs at its early stage. Our observation covered the following groups: workers employed at a metallurgic plant who had occupational contacts with industrial aerosols (exposure factors included welding and silicon-containing aerosols with predominantly fibrogenic effects in concentrations exceeding maximum permissible ones in workplace air); people suffering from chronic obstructive pulmonary disease of occupational etiology (COPD OE) in their post-exposure period; workers who didn’t have any occupational contacts with industrial aerosols. We determined neopterin contents in blood serum with ELISA test using “Neopterin ELISA” reagent kit (IBL, Hamburg). Elevated neopterin levels were detected in blood serum of 56.1 % workers who were occupationally exposed to industrial aerosols and 53.3 % of patients with COPD OE; we also found a direct correlation between levels of neopterin and interferon gamma. Only 18.7 % workers without any occupational contacts with industrial aerosols had elevated neopterin levels in their blood serum and there were no authentic correlations between these levels and interferon gamma contents in this group. Workers who were occupationally exposed to industrial aerosols had a more apparent increase in the average level of neopterin at an age younger than 40 years and working experience shorter than 20 years in comparison with workers without any such exposure. Neopterin can be used as a potential sensitive biomarker showing risks of an early inflammatory reaction in the lungs occurring in workers who are occupationally exposed to industrial aerosols. People with elevated neopterin levels in blood, especially those who are occupationally exposed to industrial aerosols, can be recommended to have their bronchi and lungs monitored in dynamics.
... To be more precise, pollution in water vapor (gaseous state) causes damage to human health and other living beings. Silicon dioxide is one of the most abundant polluting substances, which is a great risk for air pollution and, therefore, a threat to human life (Lira et al., 2012;Radnoff et al., 2014;Fazen et al., 2020). The chemical formula SiO2 stands for silicon dioxide, which is the most prevalent oxide component in the crust of the earth. ...
... To be more precise, pollution in water vapor (gaseous state) causes damage to human health and other living beings. Silicon dioxide is one of the most abundant polluting substances, which is a great risk for air pollution and, therefore, a threat to human life (Lira et al., 2012;Radnoff et al., 2014;Fazen et al., 2020). The chemical formula SiO2 stands for silicon dioxide, which is the most prevalent oxide component in the crust of the earth. ...
... Many minerals are commercially exploited and are used in a wide range of applications, including construction, ceramics, paints, fillers, plastics, electronics and abrasives [2]. Consequently, inhalation of mineral particles represents a potential health hazard in industries and occupations where rocks and minerals are mined, processed and handled [3][4][5][6]. In addition, crustal material is a common constituent of respirable ambient particulate matter, a source of exposure for the general population [7][8][9][10]. ...
Background
Respirable mineral particles represent a potential health hazard in occupational settings and ambient air. Previous studies show that mineral particles may induce cytotoxicity and inflammatory reactions in vitro and in vivo and that the potency varies between samples of different composition. However, the reason for these differences is largely unknown and the impact of mineralogical composition on the biological effects of mineral dust remains to be determined.
Methods
We have assessed the cytotoxic and pro-inflammatory effects of ten mineral particle samples of different composition in human bronchial epithelial cells (HBEC3-KT) and THP-1-derived macrophages, as well as their membranolytic properties in erythrocytes. Moreover, the results were compiled with the results of recently published experiments on the effects of stone particle exposure and analysed using linear regression models to elucidate which mineral components contribute most to the toxicity of mineral dust.
Results
While all mineral particle samples were more cytotoxic to HBEC3-KT cells than THP-1 macrophages, biotite and quartz were among the most cytotoxic in both cell models. In HBEC3-KT cells, biotite and quartz also appeared to be the most potent inducers of pro-inflammatory cytokines, while the quartz, Ca-feldspar, Na-feldspar and biotite samples were the most potent in THP-1 macrophages. All particle samples except quartz induced low levels of membranolysis. The regression analyses revealed associations between particle bioactivity and the content of quartz, muscovite, plagioclase, biotite, anorthite, albite, microcline, calcite, chlorite, orthopyroxene, actinolite and epidote, depending on the cell model and endpoint. However, muscovite was the only mineral consistently associated with increased cytotoxicity and cytokine release in both cell models.
Conclusions
The present study provides further evidence that mineral particles may induce cytotoxicity and inflammation in cells of the human airways and that particle samples of different mineralogical composition differ in potency. The results show that quartz, while being among the most potent samples, does not fully predict the toxicity of mineral dust, highlighting the importance of other particle constituents. Moreover, the results indicate that the phyllosilicates muscovite and biotite may be more potent than other minerals assessed in the study, suggesting that this group of sheet-like minerals may warrant further attention.
... Respirable mineral particles also represent a potential health hazard in several occupational settings and exposure may occur in conjunction with DEP due to the use of diesel-powered equipment, for instance in mining and tunnelling operations [11,12,19,[32][33][34]. Moreover, minerals may be major components of ambient PM and can originate from both natural sources and human activity [35][36][37]. ...
Background
People are exposed to ambient particulate matter (PM) from multiple sources simultaneously in both environmental and occupational settings. However, combinatory effects of particles from different sources have received little attention in experimental studies. In the present study, the pro-inflammatory effects of combined exposure to diesel exhaust particles (DEP) and mineral particles, two common PM constituents, were explored in human lung epithelial cells.
Methods
Particle-induced secretion of pro-inflammatory cytokines (CXCL8 and IL-1β) and changes in expression of genes related to inflammation (CXCL8, IL-1α, IL-1β and COX-2), redox responses (HO-1) and xenobiotic metabolism (CYP1A1 and CYP1B1) were assessed in human bronchial epithelial cells (HBEC3-KT) after combined exposure to different samples of DEP and mineral particles. Combined exposure was also conducted using lipophilic organic extracts of DEP to assess the contribution of soluble organic chemicals. Moreover, the role of the aryl hydrocarbon receptor (AhR) pathway was assessed using an AhR-specific inhibitor (CH223191).
Results
Combined exposure to DEP and mineral particles induced increases in pro-inflammatory cytokines and expression of genes related to inflammation and redox responses in HBEC3-KT cells that were greater than either particle sample alone. Moreover, robust increases in the expression of CYP1A1 and CYP1B1 were observed. The effects were most pronounced after combined exposure to α-quartz and DEP from an older fossil diesel, but enhanced responses were also observed using DEP generated from a modern biodiesel blend and several stone particle samples of mixed mineral composition. Moreover, the effect of combined exposure on cytokine secretion could also be induced by lipophilic organic extracts of DEP. Pre-incubation with an AhR-specific inhibitor reduced the particle-induced cytokine responses, suggesting that the effects were at least partially dependent on AhR.
Conclusions
Exposure to DEP and mineral particles in combination induces enhanced pro-inflammatory responses in human bronchial epithelial cells compared with exposure to the individual particle samples. The effects are partly mediated through an AhR-dependent pathway and lipophilic organic chemicals in DEP appear to play a central role. These possible combinatory effects between different sources and components of PM warrant further attention and should also be considered when assessing measures to reduce PM-induced health effects.
... Occupational exposure of construction workers to respirable dusts and crystalline silica dust was extensively studied by within the last two decades, especially among Canadian and American construction workers [39], [40]. Excessive exposure in our study might be due to a lack of engineering control measures and higher percentage of crystalline silica in cement and respirable dusts, compared with other countries. ...
AIM: The objective of the study was to assess the influence of exposure duration and smoking on ventilatory impairment among construction workers. METHODS: A cross-sectional study was performed, including 83 construction workers aged 18–64 years, compared to equivalent number of office controls matched by age, workplace exposure duration, and smoking status. Data on chronic respiratory symptoms, work history, and smoking status were collected by standardized questionnaire, while lung functional testing of the examined subjects was performed by spirometry. RESULTS: Mean values of spirometric parameters were lower in construction workers compared to controls with statistical significance registered for maximal expiratory flow (MEF25), MEF50, and MEF75. Lung functions of construction workers have been found to decrease in relation to exposure duration but reached significance only for small airways changes. There was a significant difference in detected ventilatory impairment between exposed workers and controls for any type of ventilatory impairment, as well as obstructive and combined ventilatory pattern and obstructive ventilatory pattern in small airways. Obstructive ventilatory impairment was significantly associated with life-time smoking in construction workers, while obstructive ventilatory pattern in small airways was significantly associated with life-time smoking. The combined effect of daily smoking, life-time smoking, and number of cigarettes smoked daily was shown to have a significant influence in their development. The risk for obstructive ventilatory pattern in small airways among exposed subjects was about 4 fold higher in those exposed more than 20 years (odds ratio [OR] = 3.68 [1.01–14.59] confidence interval [CI] 95%), and about 2.5 fold higher in smokers (OR = 2.57 [0.92-7.25] CI 95%). Exposure duration, smoking and age had independent effect only on small airways changes and force expiratory volume in the 1st s/force vital capacity %. CONCLUSION: Our data suggest the importance of the joint effect of job exposure in construction and daily smoking on the development of lung function impairment and airflow limitation, being dominant, especially on small airways.
... Several rocks and minerals are excavated for use in a range of applications, including construction, ceramics, paints, fillers, abrasives, plastics and electronics [2]. Thus, inhalation of respirable mineral particles is a potential health hazard in industries and occupations where rocks and minerals are mined, processed and handled [3][4][5][6]. In addition, mineral particles may be a major constituent in ambient particulate matter (PM), stemming from both anthropogenic activities and from natural sources [7][8][9]. ...
Background
Respirable stone- and mineral particles may be a major constituent in occupational and ambient air pollution and represent a possible health hazard. However, with exception of quartz and asbestos, little is known about the toxic properties of mineral particles. In the present study, the pro-inflammatory and cytotoxic responses to six stone particle samples of different composition and with diameter below 10 μm were assessed in human bronchial epithelial cells (HBEC3-KT), THP-1 macrophages and a HBEC3-KT/THP-1 co-culture. Moreover, particle-induced lysis of human erythrocytes was assessed to determine the ability of the particles to lyse biological membranes. Finally, the role of the NLRP3 inflammasome was assessed using a NLRP3-specific inhibitor and detection of ASC oligomers and cleaved caspase-1 and IL-1β. A reference sample of pure α-quartz was included for comparison.
Results
Several stone particle samples induced a concentration-dependent increase in cytotoxicity and secretion of the pro-inflammatory cytokines CXCL8, IL-1α, IL-1β and TNFα. In HBEC3-KT, quartzite and anorthosite were the most cytotoxic stone particle samples and induced the highest levels of cytokines. Quartzite and anorthosite were also the most cytotoxic samples in THP-1 macrophages, while anorthosite and hornfels induced the highest cytokine responses. In comparison, few significant differences between particle samples were detected in the co-culture. Adjusting responses for differences in surface area concentrations did not fully account for the differences between particle samples. Moreover, the stone particles had low hemolytic potential, indicating that the effects were not driven by membrane lysis. Pre-incubation with a NLRP3-specific inhibitor reduced stone particle-induced cytokine responses in THP-1 macrophages, but not in HBEC3-KT cells, suggesting that the effects are mediated through different mechanisms in epithelial cells and macrophages. Particle exposure also induced an increase in ASC oligomers and cleaved caspase-1 and IL-1β in THP-1 macrophages, confirming the involvement of the NLRP3 inflammasome.
Conclusions
The present study indicates that stone particles induce cytotoxicity and pro-inflammatory responses in human bronchial epithelial cells and macrophages, acting through NLRP3-independent and -dependent mechanisms, respectively. Moreover, some particle samples induced cytotoxicity and cytokine release to a similar or greater extent than α-quartz. Thus, these minerals warrant further attention in future research.
... Significant occupational exposure to crystalline silica has been reported among workers engaged mining (Peters et al., 2017), sand blasting (Radnoff et al., 2014), foundry work (Kuo et al., 2018), construction (Bello et al., 2019) and other industrial sectors. Inhalation is the main route for occupational exposure to dust containing crystalline silica, and most of the serious health effects associated with occupational exposure to crystalline silica are thought to be those affecting the lungs. ...
The pulmonary inflammatory response to inhalation exposure to a fracking sand dust (FSD 8) was investigated in a rat model. Adult male Sprague-Dawley rats were exposed by whole-body inhalation to air or an aerosol of a FSD, i.e., FSD 8, at concentrations of 10 or 30 mg/m3, 6 h/d for 4 d. The control and FSD 8-exposed rats were euthanized at post-exposure time intervals of 1, 7 or 27 d and pulmonary inflammatory, cytotoxic and oxidant responses were determined. Deposition of FSD 8 particles was detected in the lungs of all the FSD 8-exposed rats. Analysis of bronchoalveolar lavage parameters of toxicity, oxidant generation, and inflammation did not reveal any significant persistent pulmonary toxicity in the FSD 8-exposed rats. Similarly, the lung histology of the FSD 8-exposed rats showed only minimal changes in influx of macrophages following the exposure. Determination of global gene expression profiles detected statistically significant differential expressions of only six and five genes in the 10 mg/m3, 1-d post-exposure, and the 30 mg/m3, 7-d post-exposure FSD 8 groups, respectively. Taken together, data obtained from the present study demonstrated that FSD 8 inhalation exposure resulted in no statistically significant toxicity or gene expression changes in the lungs of the rats. In the absence of any information about its potential toxicity, a comprehensive rat animal model study (see Fedan, J.S., Toxicol Appl Pharmacol. 000, 000-000, 2020) has been designed to investigate the bioactivities of several FSDs in comparison to MIN-U-SIL® 5, a respirable α-quartz reference dust used in previous animal models of silicosis, in several organ systems.
... They reported relationship between airborne total respirable silica dust concentration and total respirable silica dust concentrations. The also reported that the hazard assessment tool is necessary for all employers to evaluate the potential exposure of airborne respirable silica dust particles at the work place (5). Similar findings were reported in a study conducted by Yassin A et al among patients with chronic silicosis and found similar results to present study. ...
Background: Silicosis is reported to be an occupational lung disease, which is caused by the inhalation of silica dust. Workers in occupations related to silica dust exposure are characterized by increased foci of fibrogenesis which result in radiological and pathological findings in the lungs. In most circumstances silicosis only develops subsequent to substantial occupational exposures. Material & Methods: The present prospective study was conducted at department of respiratory medicine of our tertiary care hospital. The study was an observational study conducted during a period of one year. The study done at 95% confidence interval at 10% of maximum allowable error. All patients who were diagnosed with silicosis were enrolled into the study. Results: In the present study, all patient had cough at presentation out which 7 (70%) patients had dry cough and 3 patients with productive coughs, four patients experienced loss of appetite. Eight (80%) patients had a history of smoking. Chest X-rays of all patients revealed bilateral, widespread, reticulonodular, and nodular appearances. Six patients had work on crusher machine and four patients as manual stone cutter. Pneumothorax was located bilaterally in all cases. Conclusion: We concluded from the present study that inhalation of quartz dust or silica dusts was commonly associated with adverse health effects and it can cause serious morbidity like secondary spontaneous pneumothorax and mortalities. Keywords: Silicosis, occupational lung disease, secondary spontaneous pneumothorax.
... U górników i pracowników budowlanych w Australii, górników kopalni złota w Północnej Ameryki, Południowej Ameryki, Afryce i pracujących w przemyśle odlewniczym w Pakistanie stwierdza się zwiększoną częstość zachorowania na raka płuca, gruźlicę układu oddechowego, krzemicę i choroby opłucnej [8,[13][14][15][16]. Nawet wśród osób wykonujących zawody takie jak stolarz, malarz i elektryk również stwierdzono zwiększone ryzyko zachorowania na krzemicę [17]. ...
... En varios países de todos los continentes se ha develado que la exposición a sílice en trabajos distintos de la minería ha aumentado en la medida que la industrialización y comercialización de nuevos productos y artículos con contenido de sílice se han diversificado. [21][22][23][24][25][26] Por otro lado, la crisis económica global ha puesto una voz de alarma en relación con la dificultad de monitorear la ocurrencia de enfermedades causadas por exposiciones riesgosas debido a despidos masivos de industrias formales, con la consiguiente posibilidad de instalación de trabajo informal. 27 Actualmente, en Chile se estima que 5.4% de la fuerza de trabajo ocupada, de diversos rubros, tiene alta probabilidad de exposición a este compuesto 4 , razón por lo cual esta situación se considera un problema prioritario de salud ocupacional chilena. ...
Introduction: Silicosis is a progressive lung disease, irreversible, but potentially preventable. Knowing the perception of risk in workers exposed to silica is necessary to intervene and reduce the incidence of silicosis and other related diseases. The objective of this study was to validate a Questionnaire of risk perception of occupational expo sure to silica (CuPREOS) in exposed workers, in different work activities in Temuco, Chile. Material and method: A stage of explo ration with phenomenological/naturalist approach allowed to create categories of first and second order, which ended in a first version of the instrument. The second stage included exploratory and con firmatory factor analysis. Results: two underlying dimensions were revealed: a) evidence of risk, in which worker states to evaluate signals of alarm and b) absence of risk, in which he weighs aspects that counteract the previous ones. Both set up the conceptual frame work that sustain the CuPREOS of 9 items/questions, with a reliabil ity of 0.84 (Cronbach alfa). The confirmatory analysis indicators show a good fit of the model. Discussion: the perception of risk is a construct involving social and cultural complexities, its measurement should be simple and practical; its knowledge would enable more effective decision-making in prevention and intervention.
... was similar to the findings reported by Tjoe-Nij Rappaport and Flanagan among Canadian and American construction workers(45)(46)(47). However, occupational exposure of construction workers in our research was higher than exposures in recent studies on Canadian and American construction workers(48,49). Excessive exposure in this study might be due to lack of engineering control measures and higher percentage of crystalline silica in Iranian cement and PNOS, compared with other countries.Due to lack of data on the lung function parameters of construction workers in Iran, we examined the workers' lung function parameters. The mean lung function parameters, including FVC% and FEV1%, were significantly lower among exposed construction workers, compared to the control group. ...
Background
Aerosols generated during construction activities are an integral part of building operations. Considering the nature of materials used in construction activities, respirable dust contains crystalline silica and particulates not otherwise specified (PNOS). Due to lack of data regarding the occupational health status of Iranian construction workers, the objective of this study was to evaluate occupational exposure to silica and to examine their respiratory health status.
Materials and Methods
In this cross sectional study, 85 construction workers and 40 controls (without active exposure to construction dust) were studied. The workers’ exposure to PNOS and silica aerosols was monitored by the NIOSH method No.0600 and a new Fourier transform infrared spectroscopy (FTIR)-based method, respectively. All subjects were also monitored for lung function parameters, such as forced expiratory volume/forced vital capacity (FEV1/FVC), peak expiratory flow rate (PEFR), forced expiratory flow (FEF25–75), FVC, and FEV1.
Results
The mean exposure of workers to respirable PNOS and silica was 9.8 (0.35) and 0.13 (0.019) mg/m³, respectively. The groups of construction workers showed significant differences in exposure to PNOS (P< 0.001) and silica (P= 0.007). The mean pulmonary function parameters, including FEV1% and FVC%, were significantly lower among construction workers, compared to the control group (P< 0.001 and P= 0.009, respectively). The pulmonary status of 51.8% of construction workers showed moderate restriction, while 4.70% exhibited obstruction.
Conclusion
Considering the construction workers’ excessive exposure to PNOS and silica, besides depressed lung function parameters, they can be classified as a high-risk group for respiratory diseases.
... Apart from smoking, risk factors for COPD include occupational dust and chemicals including and ceilings with gypsum boards, roof and floor work plus minor insulation work. Based on previous dust measurements, carpenters were expected to have a low level of exposure to dust [9,12,16]. ...
Objective: This study investigated whether Danish construction workers had an increased prevalence of chronic obstructive pulmonary disease (COPD) or affected lung function and if the prevalence differed between types of jobs within construction. Methods: A cross-sectional study of 899 Danish male workers: demolition workers, insulators, carpenters and a control group of hospital porters aged 35-60 years answered a questionnaire and performed spirometry. Results were tested statistically for differences between occupational groups, and all analyses were adjusted for smoking status, age and body mass index. Results: COPD (Global Initiative on Obstructive Lung Disease 2-4) was found in 2.4% of carpenters, 4.7% of insulators, 7.8% of demolition workers and 6.1% of hospital porters (P = 0.055). Compared to hospital porters, demolition workers had significantly increased odds of coughing more than average [odds ratio (OR) = 2.2, 95% confidence interval (CI) 1.2-3.8] and carpenters had significantly lower odds of forced expiratory volume in one second below the lower limit of normal (i.e. FEV 1 < LLN) (OR = 0.5, 95% CI 0.2-0.9). The OR of FEV 1 < LLN for demolition workers compared to carpenters was 2.7 (95% CI 1.3-5.5) and for insulators compared to carpenters was 1.8 (95% CI 0.8-3.9). Demolition workers had significantly lower odds compared to all other groups for forced vital capacity < LLN.
... Studies have shown that airborne pathogens, carcinogens, allergens as well as pollutants have affected the human health in various ways leading to various disorders like asthma, bronchitis, pneumonia and various other chronic disorders (Baldacci et al., 2015;Del Donno et al., 2002;Hubaux et al., 2012, Mortimer et al., 2012Tanabe et al., 2015). It was reported earlier, that localized concentration of several airborne matter like asbestos, silicon and arsenic leads to development of pulmonary disorders like asbestosis, silicosis and arsenicosis (Bang et al., 2015;Boulanger et al., 2014;d'Errico et al., 2009;Finkelstein, 2013;Halatek et al., 2009;Radnoff et al., 2014;Sen, 2015). Physiological impact upon pollutant exposure includes pulmonary clogging, alveolar loss as well as reduction in the alveolar elasticity. ...
... Worker exposure to respirable crystalline silica can occur in agriculture, foundry work, hydraulic fracturing, mining, sandblasting, stone and granite work, and construction. (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13) Many construction tasks have been associated with overexposure to crystalline silica. (14,15) Among these tasks are tuck pointing, concrete sawing, concrete grinding, concrete scabbling, jackhammering, installing roof tiles, and abrasive blasting. ...
Asphalt pavement milling machines use a rotating cutter drum to remove the deteriorated road surface for recycling. The removal of the road surface has the potential to release respirable crystalline silica, to which workers can be exposed. This article describes an evaluation of respirable crystalline silica exposures to the operator and ground worker from two different half-lane and larger asphalt pavement milling machines that had ventilation dust controls and water-sprays designed and installed by the manufacturers.
Manufacturer A completed milling for 11 days at 4 highway construction sites in Wisconsin, and Manufacturer B completed milling for 10 days at 7 highway construction sites in Indiana. To evaluate the dust controls, full-shift personal breathing zone air samples were collected from an operator and ground worker during the course of normal employee work activities of asphalt pavement milling at 11 different sites.
Forty-two personal breathing zone air samples were collected over 21 days (sampling on an operator and ground worker each day). All samples were below 50 µg/m³ for respirable crystalline silica, the National Institute for Occupational Safety and Health recommended exposure limit. The geometric mean personal breathing zone air sample was 6.2 µg/m³ for the operator and 6.1 µg/m³ for the ground worker for the Manufacturer A milling machine. The geometric mean personal breathing zone air sample was 4.2 µg/m³ for the operator and 9.0 µg/m³ for the ground worker for the Manufacturer B milling machine. In addition, upper 95% confidence limits for the mean exposure for each occupation were well below 50 µg/m³ for both studies. The silica content in the bulk asphalt material being milled ranged from 7–23% silica for roads milled by Manufacturer A and from 5–12% silica for roads milled by Manufacturer B.
The results indicate that engineering controls consisting of ventilation controls in combination with water-sprays are capable of controlling occupational exposures to respirable crystalline silica generated by asphalt pavement milling machines on highway construction sites.
... 있으며 (IARC, 1997) (Peters et al., 2009), 건설공사 현장에서의 결정형 규산의 노출 수준 (Radnoff et al., 2014) 등 다양한 연구가 진행되어져 왔다 (Mieke et al., 2001;Woskie et al., 2002). 그러나 국내에서 석영 의 노출수준과 관련된 연구는 1980년대부터 주 대상 이 석탄 광업이었으며 (Choi et al., 1987, Song & Lee, 1994, 제조업의 경우 주물, 요업, 시멘트 및 콘크리 트 등 여러 사업장을 대상으로 노출평가가 수행되었 다 (Jeoung et al., 1995;Phee et al., 1997;Kim et al., 1998;Kim et al., 1999;Bae et al., 2013 (Balaan & Banks, 1995;Smith, 1992;Kelly, 1995;IARC, 1997 ...
Objectives: The purpose of this study was to evaluate quartz concentrations in airborne total and respirable dusts. Materials: Respirable dust samples were collected using a 10 mm aluminum cyclone equipped with a 37 mm5?m pore size PVC filter. Total dust samples were collected with a three stage cassette from three work sections at earthwork sites located in the South Chungcheong-do Province area. Results: The geometric means of quartz concentrations were 0.008mg/m^3 and 0.004mg/m^3 in total dust and respirable dust, respectively. The geometric means of quartz contents analyzed by FTIR were 3.74% in total dust and 3.16% in respirable dust. The geometric mean of quartz concentrations and contents in secondary blasting operations were higher than those in other operations. Conclusions: Given that secondary blasting operations had higher quartz concentrations, there is a need to reduce respirable dust, such as through wet operations.
Background: Lithium is an essential commodity; however, its mining and processing can expose miners to airborne contaminants such as inhalable dust, respirable dust and respirable crystalline silica. These exposures may adversely affect respiratory health. To protect the health of miners, exposure assessment and control activities are required, followed by respiratory health monitoring to assess the effect of exposure on respiratory health. This study aimed to investigate the relationship between workgroup exposure to airborne contaminants and respiratory health. To determine group exposure levels, exposure data was collected at the group level, which limits individual-level inference, followed by health monitoring. Methods: Industry health monitoring data were collected from miners in three surface lithium mines in Western Australia for the period between October 2023 and October 2024. Miners from Management Administration & Technical, Crusher/Dry/Wet Plant, and Laboratory Operations participated in a pulmonary function test, completed a health and exposure questionnaire and underwent a low dose high-resolution computed tomography. Multivariable linear and logistic regression models were fitted to identify factors associated with lung function and respiratory symptoms. Results: Older age, smoking and pre-existing respiratory conditions were correlated with poor respiratory airflow. The odds of having a respiratory obstruction or restriction were significantly higher by 3.942 and 2.165 times respectively, for miners who were 40 years old or above, and those who had existing diagnosed respiratory medical conditions. The risk of coughing among current smokers was more than four times higher compared to non-smokers. In addition, working in Crushing and Processing was significantly associated with the risk of experiencing respiratory symptoms compared to working in Management Administration & Technical and Laboratory Operations. Conclusions: The study demonstrated that respiratory health was influenced by non-work-related risk factors. Based on these results, it is recommended that health promotion programs be developed and implemented to empower miners to cease smoking and to manage non-work-related respiratory conditions.
Crystalline silica is one of the most abundant minerals on Earth. More than 230 million individuals around the world, and more than 2 million workers in the United States, predominantly in construction and mining occupations, are exposed to silica every year. Inhalation of crystalline silica leads to the development of silicosis, a progressive pneumoconiosis characterized by chronic lung inflammation and fibrosis, for which no specific therapy is available. Silicosis is also associated with increased risk of tuberculosis, lung cancer, chronic obstructive pulmonary disease (COPD), kidney disease, and autoimmune disease. These health risks remain elevated even after silica exposure has ceased. Although preventive measures have decreased the mortality attributable to silica exposure in the past decade, this occupational lung disease still kills about 100 people every year in the United States, according to the National Institute for Occupational Safety and Health (NIOSH). Between 1999 and 2013, silicosis was the underlying or contributing cause of death for about 2000 people, and 300 deaths occurred each year between 1991 and 1995, while it decreased to about 100 per year in 2012 and 2013. Data from NIOSH show that a large number of workers are at increased risk for silicosis because of exposure to silica levels that exceed current regulatory standards. Therefore, regulatory agencies have been forced to further reduce the permissible exposure levels (PEL) to 25 μg/m ³ (micrograms of silica per cubic meter of air) over an 8‐h shift, to improve prophylaxis. Despite these efforts, silicosis remains a global health threat.
Task-based respirable crystalline silica (RCS) exposure monitoring data was collected from construction work sites across 3 Canadian provinces: Alberta, British Columbia (BC), and Manitoba. In total 373 RCS samples were obtained from 70 worksites across 44 companies. Sampling was conducted between May 2015 and August 2020. The overall geometric mean (GM) RCS exposure was 0.045 mg/m3 (geometric standard deviation, GSD = 6.8). Alberta had the highest average exposure and the highest variability with GM of 0.060 mg/m3 (GSD = 9.3), the GM in BC was 0.044 (GSD = 4.3), and in Manitoba the GM was 0.033 (GSD = 7.0). A multivariable model was built using forward stepwise linear regression modeling. Province, task type, work environment (indoor vs. outdoor), construction material, sampling duration, and engineering control use were all statistically significant predictors of exposure level in partial F-tests (P < 0.05). Overall, the model explained 42% of the RCS concentration variability. Task type contributed most to the model's explanatory power. The task type with highest average exposure levels was demolition (GM 0.30 mg/m3, GSD 0.49). Breaking (GM 0.16 mg/m3, GSD 8.4) and grinding (GM 0.081 m/m3, GSD 7.4) also had high-exposure levels. Working outdoors was associated with exposure levels 39% lower than indoors. Exposure control measures such as local exhaust ventilation and wetting were also associated with lower exposure levels. Among construction materials, Cement, sand, and stone were associated with higher RCS exposure levels relative to the reference material, concrete. The results of this study indicate that workers in western Canada remain exposed to RCS at levels that exceed the health-based American Congress for Governmental Industrial Hygienists Threshold Limit Value of 0.025 mg/m3. Although there were some differences in exposure levels between the provinces, the determinants of exposure were similar in all 3. The overall GM RCS exposure was 0.045 mg/m3 (geometric standard deviation, GSD = 6.8). Alberta had the highest average exposure and the highest variability with GM of 0.060 mg/m3 (GSD = 9.3), the GM in BC was 0.044 (GSD = 4.3), and in Manitoba the GM was 0.033 (GSD = 7.0).
Background:
The World Health Organization (WHO) and the International Labour Organization (ILO) are developing joint estimates of the work-related burden of disease and injury (WHO/ILO Joint Estimates), with contributions from a large number of individual experts. Evidence from human, animal and mechanistic data suggests that occupational exposure to dusts and/or fibres (silica, asbestos and coal dust) causes pneumoconiosis. In this paper, we present a systematic review and meta-analysis of the prevalences and levels of occupational exposure to silica, asbestos and coal dust. These estimates of prevalences and levels will serve as input data for estimating (if feasible) the number of deaths and disability-adjusted life years that are attributable to occupational exposure to silica, asbestos and coal dust, for the development of the WHO/ILO Joint Estimates.
Objectives:
We aimed to systematically review and meta-analyse estimates of the prevalences and levels of occupational exposure to silica, asbestos and coal dust among working-age (≥ 15 years) workers.
Data sources:
We searched electronic academic databases for potentially relevant records from published and unpublished studies, including Ovid Medline, PubMed, EMBASE, and CISDOC. We also searched electronic grey literature databases, Internet search engines and organizational websites; hand-searched reference lists of previous systematic reviews and included study records; and consulted additional experts.
Study eligibility and criteria:
We included working-age (≥ 15 years) workers in the formal and informal economy in any WHO and/or ILO Member State but excluded children (< 15 years) and unpaid domestic workers. We included all study types with objective dust or fibre measurements, published between 1960 and 2018, that directly or indirectly reported an estimate of the prevalence and/or level of occupational exposure to silica, asbestos and/or coal dust.
Study appraisal and synthesis methods:
At least two review authors independently screened titles and abstracts against the eligibility criteria at a first stage and full texts of potentially eligible records at a second stage, then data were extracted from qualifying studies. We combined prevalence estimates by industrial sector (ISIC-4 2-digit level with additional merging within Mining, Manufacturing and Construction) using random-effects meta-analysis. Two or more review authors assessed the risk of bias and all available authors assessed the quality of evidence, using the ROB-SPEO tool and QoE-SPEO approach developed specifically for the WHO/ILO Joint Estimates.
Results:
Eighty-eight studies (82 cross-sectional studies and 6 longitudinal studies) met the inclusion criteria, comprising > 2.4 million measurements covering 23 countries from all WHO regions (Africa, Americas, Eastern Mediterranean, South-East Asia, Europe, and Western Pacific). The target population in all 88 included studies was from major ISCO groups 3 (Technicians and Associate Professionals), 6 (Skilled Agricultural, Forestry and Fishery Workers), 7 (Craft and Related Trades Workers), 8 (Plant and Machine Operators and Assemblers), and 9 (Elementary Occupations), hereafter called manual workers. Most studies were performed in Construction, Manufacturing and Mining. For occupational exposure to silica, 65 studies (61 cross-sectional studies and 4 longitudinal studies) were included with > 2.3 million measurements collected in 22 countries in all six WHO regions. For occupational exposure to asbestos, 18 studies (17 cross-sectional studies and 1 longitudinal) were included with > 20,000 measurements collected in eight countries in five WHO regions (no data for Africa). For occupational exposure to coal dust, eight studies (all cross-sectional) were included comprising > 100,000 samples in six countries in five WHO regions (no data for Eastern Mediterranean). Occupational exposure to silica, asbestos and coal dust was assessed with personal or stationary active filter sampling; for silica and asbestos, gravimetric assessment was followed by technical analysis. Risk of bias profiles varied between the bodies of evidence looking at asbestos, silica and coal dust, as well as between industrial sectors. However, risk of bias was generally highest for the domain of selection of participants into the studies. The largest bodies of evidence for silica related to the industrial sectors of Construction (ISIC 41-43), Manufacturing (ISIC 20, 23-25, 27, 31-32) and Mining (ISIC 05, 07, 08). For Construction, the pooled prevalence estimate was 0.89 (95% CI 0.84 to 0.93, 17 studies, I2 91%, moderate quality of evidence) and the level estimate was rated as of very low quality of evidence. For Manufacturing, the pooled prevalence estimate was 0.85 (95% CI 0.78 to 0.91, 24 studies, I2 100%, moderate quality of evidence) and the pooled level estimate was rated as of very low quality of evidence. The pooled prevalence estimate for Mining was 0.75 (95% CI 0.68 to 0.82, 20 studies, I2 100%, moderate quality of evidence) and the pooled level estimate was 0.04 mg/m3 (95% CI 0.03 to 0.05, 17 studies, I2 100%, low quality of evidence). Smaller bodies of evidence were identified for Crop and animal production (ISIC 01; very low quality of evidence for both prevalence and level); Professional, scientific and technical activities (ISIC 71, 74; very low quality of evidence for both prevalence and level); and Electricity, gas, steam and air conditioning supply (ISIC 35; very low quality of evidence for both prevalence and level). For asbestos, the pooled prevalence estimate for Construction (ISIC 41, 43, 45,) was 0.77 (95% CI 0.65 to 0.87, six studies, I2 99%, low quality of evidence) and the level estimate was rated as of very low quality of evidence. For Manufacturing (ISIC 13, 23-24, 29-30), the pooled prevalence and level estimates were rated as being of very low quality of evidence. Smaller bodies of evidence were identified for Other mining and quarrying (ISIC 08; very low quality of evidence for both prevalence and level); Electricity, gas, steam and air conditioning supply (ISIC 35; very low quality of evidence for both prevalence and level); and Water supply, sewerage, waste management and remediation (ISIC 37; very low quality of evidence for levels). For coal dust, the pooled prevalence estimate for Mining of coal and lignite (ISIC 05), was 1.00 (95% CI 1.00 to 1.00, six studies, I2 16%, moderate quality of evidence) and the pooled level estimate was 0.77 mg/m3 (95% CI 0.68 to 0.86, three studies, I2 100%, low quality of evidence). A small body of evidence was identified for Electricity, gas, steam and air conditioning supply (ISIC 35); with very low quality of evidence for prevalence, and the pooled level estimate being 0.60 mg/m3 (95% CI -6.95 to 8.14, one study, low quality of evidence).
Conclusions:
Overall, we judged the bodies of evidence for occupational exposure to silica to vary by industrial sector between very low and moderate quality of evidence for prevalence, and very low and low for level. For occupational exposure to asbestos, the bodies of evidence varied by industrial sector between very low and low quality of evidence for prevalence and were of very low quality of evidence for level. For occupational exposure to coal dust, the bodies of evidence were of very low or moderate quality of evidence for prevalence, and low for level. None of the included studies were population-based studies (i.e., covered the entire workers' population in the industrial sector), which we judged to present serious concern for indirectness, except for occupational exposure to coal dust within the industrial sector of mining of coal and lignite. Selected estimates of the prevalences and levels of occupational exposure to silica by industrial sector are considered suitable as input data for the WHO/ILO Joint Estimates, and selected estimates of the prevalences and levels of occupational exposure to asbestos and coal dust may perhaps also be suitable for estimation purposes. Protocol identifier: https://doi.org/10.1016/j.envint.2018.06.005. PROSPERO registration number: CRD42018084131.
Air pollution is known as one of the most important causes of death in the whole world. Therefore, pollution reduction to achieve clean air was noticed by everyone. This way, using nanotechnology to control air and monitor is a novel approach. This paper investigates the effect of the number of graphene nano-pores on the SiO 2 separation from the H 2 O vapour in the presence of an external electric field with the magnitude of 0.01 V/Å using the molecular dynamics (MD) method. The electric field affects the charged particles and causes disturbance in the structure. It also prevents SiO 2 nanoparticles from passing through the carbon nanosheet. Also, the presence of carbon nanosheets acts as a membrane and affects the diffusion of water in the nanostructure. So the results show that in the presence of a nano-pore, the number of H 2 O molecules reaches 496 and 568 in reservoirs 2 and 3. Also, the number of SiO 2 nanoparticles reaches 10 and 4 in reservoirs 2 and 3. This shows that in reservoirs 2 and 3, about 80% and 60% of the SiO 2 nanoparticles are separated. As mentioned before, the electric field prevents the passage of SiO 2 nanoparticles through the carbon nanosheet. As the number of graphene nano-pores increases by 2, 3, 4, and 5, the number of passing water molecules increases. Considering that the number of graphene nano-pores has increased and the movement path of particles has increased, the number of passing particles almost increases. However, the electric field prevents the passage of SiO 2 nanoparticles. According to the results, the suggested setup can be employed for designing highly efficient nanostructured membranes for air purification and monitoring.
Our research goal was to estimate neopterin level in blood serum of workers occupationally exposed to industrial aerosols with predominantly fibrogenic effects; to establish a relationship between this level and workers’ age, working experience in hazardous working conditions, spirometric parameters and the level of C-reactive protein. We also aimed to assess neopterin as a possible biomarker showing risks of the developing inflammatory process in the bronchi and lungs at its early stage. Our observation covered the following groups: workers employed at a metallurgic plant who had occupational contacts with industrial aerosols (exposure factors included welding and silicon-containing aerosols with predominantly fibrogenic effects in concentrations exceeding maximum permissible ones in workplace air); people suffering from chronic obstructive pulmonary disease of occupational etiology (COPD OE) in their post-exposure period; workers who didn’t have any occupational contacts with industrial aerosols. We determined neopterin contents in blood serum with ELISA test using “Neopterin ELISA” reagent kit (IBL, Hamburg). Elevated neopterin levels were detected in blood serum of 56.1 % workers who were occupationally exposed to industrial aerosols and 53.3 % of patients with COPD OE; we also found a direct correlation between levels of neopterin and interferon gamma. Only 18.7 % workers without any occupational contacts with industrial aerosols had elevated neopterin levels in their blood serum and there were no authentic correlations between these levels and interferon gamma contents in this group. Workers who were occupationally exposed to industrial aerosols had a more apparent increase in the average level of neopterin at an age younger than 40 years and working experience shorter than 20 years in comparison with workers without any such exposure. Neopterin can be used as a potential sensitive biomarker showing risks of an early inflammatory reaction in the lungs occurring in workers who are occupationally exposed to industrial aerosols. People with elevated neopterin levels in blood, especially those who are occupationally exposed to industrial aerosols, can be recommended to have their bronchi and lungs monitored in dynamics.
Objective:
We investigated long-term economic impacts of respirable crystalline silica (RCS) removal interventions in the construction at the societal level.
Methods:
We estimated costs and benefits of two RCS exposure interventions, use of "respirators" and "wet method," over a 30-year time period. We identified economic impacts of the interventions under four different scenarios.
Results:
Under current practices, we estimated that approximately 125 lung cancer cases attributable to RCS exposure would arise in 2060. Under the full exposure removal scenario, we estimated there would be 53 new cases. Over the 30-year time period, the estimated cumulative averted cases are 787 and 482 for respirators and wet method, respectively, which amount to net benefits of 394.92 million.
Conclusions:
Findings provide important information for policymakers seeking to reduce the economic burden of occupational lung cancer in society.
The ends of chromosomes shorten at each round of cell division, and this process is thought to be affected by occupational exposures. Occupational hazards may alter telomere length homeostasis resulting in DNA damage, chromosome aberration, mutations, epigenetic alterations and inflammation. Therefore, for the protection of genetic material, nature has provided a unique nucleoprotein structure known as a telomere. Telomeres provide protection by averting an inappropriate activation of the DNA damage response (DDR) at chromosomal ends and preventing recognition of single and double strand DNA (ssDNA and dsDNA) breaks or chromosomal end-to-end fusion. Telomeres and their interacting six shelterin complex proteins in coordination act as inhibitors of DNA damage machinery by blocking DDR activation at chromosomes, thereby preventing the occurrence of genome instability, perturbed cell cycle, cellular senescence and apoptosis. However, inappropriate DNA repair may result in the inadequate distribution of genetic material during cell division, resulting in the eventual development of tumorigenesis and other pathologies. This article reviews the current literature on the association of changes in telomere length and its interacting proteins with different occupational exposures and the potential application of telomere length or changes in the regulatory proteins as potential biomarkers for exposure and health response, including recent findings and future perspectives.
Background: Though there is extensive research on occupational exposure in production mines, there is limited information on exposure during the exploration phase of mining.
Methods: Air samples were collected in a core processing facility in Northern Ontario, Canada. All samples were analyzed for respirable dust (NIOSH 0600) and respirable crystalline silica (NIOSH 7602). Mean exposure levels were estimated and differences in exposure between work areas were investigated.
Results: Sixteen personal and nine area air samples were collected. Respirable dust exposure ranged from < LOD to 2.24mg-m⁻³; respirable silica exposure ranged from < LOD to 0.055mg-m⁻³. Silica concentrations were higher among workers in the core cutting and core sorting (pulp and reject) areas, as compared to those in the core logging area.
Conclusions: Workers employed in core processing facilities as part of mining exploration activities are exposed to respirable silica; exposure controls may be needed.
An understanding of the mechanisms underlying diseases is critical for their prevention. Excessive exposure to crystalline silica is a risk factor for silicosis, a potentially fatal pulmonary disease. Male Fischer 344 rats were exposed by inhalation to crystalline silica (15 mg/m³, six hours/day, five days) and pulmonary response was determined at 44 weeks following termination of silica exposure. Additionally, global gene expression profiling in lungs and BAL cells and bioinformatic analysis of the gene expression data were done to understand the molecular mechanisms underlying the progression of pulmonary response to silica. A significant increase in lactate dehydrogenase activity and albumin content in BAL fluid (BALF) suggested silica-induced pulmonary toxicity in the rats. A significant increase in the number of alveolar macrophages and infiltrating neutrophils in the lungs and elevation in monocyte chemoattractant protein-1 (MCP-1) in BALF suggested the induction of pulmonary inflammation in the silica exposed rats. Histological changes in the lungs included granuloma formation, type II pneumocyte hyperplasia, thickening of alveolar septa and positive response to Masson’s trichrome stain. Microarray analysis of global gene expression detected 94 and 225 significantly differentially expressed genes in the lungs and BAL cells, respectively. Bioinformatic analysis of the gene expression data identified significant enrichment of several disease and biological function categories and canonical pathways related to pulmonary toxicity, especially inflammation. Taken together, these data suggested the involvement of chronic inflammation as a mechanism underlying the progression of pulmonary response to exposure of rats to crystalline silica at 44 weeks following termination of exposure.
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 paper 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 detail, 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. Generally, when respirators were used, they were correctly selected for the level of measured exposure. However, not all workers who were potentially over-exposed 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.
New technologies continue to be introduced into the workplace and the environment. These novel technologies also bring in new hazards leading to evolving patterns of established occupational and environmental diseases, as well as novel conditions never before encountered.
Many of these emerging conditions have appeared in media outlets or in the literature as case reports. These sentinel cases often serve as a warning sign for subsequent outbreaks. This review will discuss environmental and occupational lung diseases and exposures from a global perspective. These diseases and exposures include environmental exposure to asbestos and lung diseases, accelerated silicosis in sandblasting jean workers, coal worker's pneumoconiosis in surface coal miners, health effects of indoor air pollution from burning of biomass fuels and exposures to heavy metals and potential health effects from hydraulic fracturing (fracking). Other emerging conditions are also discussed, including smog in developing countries, sand storms in Asia and the Middle East and respiratory illnesses from nanoparticles and man-made fibres.
Clinicians must remain vigilant for potential occupational and environmental exposures, especially when evaluating patients with unusual and unique presentation, so that occupational and environmental risk factors may be identified, and monitoring and preventive measures can be implemented early.
Objectives:
To study potential exposures to crystalline silica and the number of work-related cases of silicosis occurring in Alberta.
Methods:
Exposure data comprising 343 occupational samples were collected at 40 worksites across 13 industries. To assess silicosis reporting, cases reported to the Alberta government, claims accepted by the Workers' Compensation Board for work-related silicosis, and billings to Alberta Health for medical services with a diagnostic code for silicosis during a similar time period were compared.
Results:
Workers potentially over-exposed to airborne respirable crystalline silica were identified at most of the worksites evaluated. There were large discrepancies in the number of silicosis cases found.
Conclusions:
Many Alberta workers may be over-exposed to airborne respirable crystalline silica, and the incidence of work-related silicosis in Alberta may not be adequately represented by the official statistics.
Background:
Crystalline silica is a human carcinogen and its use is widespread among construction, mining, foundries, and other manufacturing industries.
Purpose:
To evaluate occupational exposure to crystalline silica in Italy.
Methods:
Data were collected from exposure registries and descriptive statistics were calculated for exposure-related variables. The number of potentially exposed workers was estimated in a subset of industrial sectors. Linear mixed model analysis was performed to determine factors affecting the exposure level.
Results:
We found 1387 cases of crystalline silica exposure between 1996 and 2012. Exposure was most common in construction work (AM = 0·057 mg/m(3), N = 505), and among miners and quarry workers (AM = 0·048 mg/m(3), N = 238). We estimated that 41 643 workers were at risk of exposure in the selected industrial sectors during the same period.
Conclusions:
This study identified high-risk sectors for occupational exposure to crystalline silica, which can help guide targeted dust control interventions and health promotion campaigns in the workplace.
This report describes a previously uncharacterized occupational health hazard: work crew exposures to respirable crystalline silica during hydraulic fracturing. Hydraulic fracturing involves high pressure injection of large volumes of water and sand, and smaller quantities of well treatment chemicals, into a gas or oil well to fracture shale or other rock formations, allowing more efficient recovery of hydrocarbons from a petroleum-bearing reservoir. Crystalline silica (“frac sand”) is commonly used as a proppant to hold open cracks and fissures created by hydraulic pressure. Each stage of the process requires hundreds of thousands of pounds of quartz containing sand; millions of pounds may be needed for all zones of a well. Mechanical handling of frac sand creates respirable crystalline silica dust, a potential exposure hazard for workers. Researchers at the National Institute for Occupational Safety and Health collected 111 personal breathing zone samples at 11 sites in five states to evaluate worker exposures to respirable crystalline silica during hydraulic fracturing. At each of the 11 sites, full-shift samples exceeded occupational health criteria (e.g., the Occupational Safety and Health Administration calculated permissible exposure limit, the NIOSH recommended exposure limit, or the ACGIH threshold limit value), in some cases, by 10 or more times the occupational health criteria. Based on these evaluations, an occupational health hazard was determined to exist for workplace exposures to crystalline silica. Seven points of dust generation were identified, including sand handling machinery and dust generated from the work site itself. Recommendations to control exposures include product substitution (when feasible), engineering controls or modifications to sand handling machinery, administrative controls, and use of personal protective equipment. To our knowledge, this represents the first systematic study of work crew exposures to crystalline silica during hydraulic fracturing. Companies that conduct hydraulic fracturing using silica sand should evaluate their operations to determine the potential for worker exposure to respirable crystalline silica and implement controls as necessary to protect workers.
[Supplementary materials are available for this article. Go to the publisher’s online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: a file containing controls and recommendations to limit worker exposures to respirable crystalline silica at hydraulic fracturing work sites.]
To investigate the risk of silicosis among tin miners and to investigate the relation between silicosis and cumulative exposure to dust (Chinese total dust and respirable crystalline silica dust).
A cohort study of 3010 miners exposed to silica dust and employed for at least 1 year during 1960-5 in any of four Chinese tin mines was conducted. Historical total dust data from China were used to create a job exposure matrix for facility, job title, and calendar year. The total dust exposure data from China were converted to estimates of exposure to respirable crystalline silica for comparison with findings from other epidemiological studies of silicosis. Each worker's work history was abstracted from the complete employment records in mine files. Diagnoses of silicosis were based on 1986 Chinese pneumoconiosis Roentgen diagnostic criteria, which classified silicosis as stages I-III-similar to an International Labour Organisation (ILO) classification of 1/1 or greater.
There were 1015 (33.7%) miners identified with silicosis, who had a mean age of 48.3 years, with a mean of 21.3 years after first exposure (equivalent to 11.0 net years in a dusty job). Among those who had silicosis, 684 miners (67.4%) developed silicosis after exposure ended (a mean of 3.7 years after). The risk of silicosis was strongly related to cumulative exposure to silica dust and was well fitted by the Weibull distribution, with the risk of silicosis less than 0.1% when the Chinese measure of cumulative exposure to total dust (CTD) was under 10 mg/m(3)-years (or 0.36 mg/m(3)-years of respirable crystalline silica), increasing to 68.7% when CTD exposure was 150 mg/m(3)-years (or 5.4 mg/m(3)-years of respirable crystalline silica). Latency period was not correlated to the risk of silicosis or cumulative dose of exposure. This study predicts about a 36% cumulative risk of silicosis for a 45 year lifetime exposure to these tin mine dusts at the CTD exposure standard of 2 mg/m(3), and a 55% risk at 45 years exposure to the current United States Occupational Safety and Health Administration and Mine Safety and Health Administration standards of 0.1 mg/m(3) 100% respirable crystalline silica dust.
A clear exposure-response relation was detected for silicosis in Chinese tin miners. The study results were similar to most, but not all, findings from other large scale exposure-response studies.
Exposures to respirable dust and silica were investigated among 36 construction sites in the USA. Personal measurements (n = 151) were analyzed from 80 workers in four trades, namely bricklayers, painters (while abrasive blasting), operating engineers and laborers. Painters had the highest exposures (median values for respirable dust and silica: 13.5 and 1.28 mg/m(3), respectively), followed by laborers (2.46 and 0.350 mg/m(3)), bricklayers (2.13 and 3.20 mg/m(3)) and operating engineers (0.720 and 0.075 mg/m(3)). Mixed models were fitted to the log-transformed air levels to estimate the means and within- and between-worker variance components of the distributions in each trade. We refer to the likelihood that a typical worker from a given trade would be exposed, on average, above the occupational exposure limit (OEL) as the probability of overexposure. Given US OELs of 0.05 mg/m(3) for respirable silica and 3 mg/m(3) for respirable dust, we estimated probabilities of overexposure as between 64.5 and 100% for silica and between 8.2 and 89.2% for dust; in no instance could it be inferred with certainty that this probability was <10%. This indicates that silica exposures are grossly unacceptable in the US construction industry. While engineering and administrative interventions are needed to reduce overall air levels, the heterogeneous exposures among members of each trade suggest that controls should focus, in part, upon the individual sites, activities and equipment involved. The effects of current controls and workplace characteristics upon silica exposures were investigated among operating engineers and laborers. Silica exposures were significantly reduced by wet dust suppression (approximately 3-fold for laborers) and use of ventilated cabs (approximately 6-fold for operating engineers) and were significantly increased indoors (about 4-fold for laborers). It is concluded that urgent action is required to reduce silica exposures in the US construction industry.
We describe an emerging public health concern regarding silicosis in the fast-growing highway repair industry.
We examined highway construction trends, silicosis surveillance case data, and environmental exposure data to evaluate the risk of silicosis among highway repair workers. We reviewed silicosis case data from the construction industry in 3 states that have silicosis registries, and we conducted environmental monitoring for silica at highway repair work sites.
Our findings indicate that a large population of highway workers is at risk of developing silicosis from exposure to crystalline silica.
Exposure control methods, medical screenings, protective health standards, and safety-related contract language are necessary for preventing future occupational disease problems among highway repair workers.
In 1997, a Monograph from the International Agency for Research on Cancer (IARC) classified occupational exposure to crystalline silica as carcinogenic to humans. Large amounts of epidemiological data have been published subsequently.
We conducted a systematic review of epidemiological investigations on silica exposure and lung cancer risk published after the IARC Monograph, including 28 cohort, 15 case-control and two proportionate mortality ratio (PMR) studies. These were identified in the available literature.
The pooled RR of lung cancer, calculated using random effects models, from all cohort studies considering occupational exposure to silica was 1.34. The RRs were 1.69 in cohort studies of silicotics only, 1.25 in studies where silicosis status was undefined and 1.19 among non silicotic subjects. The pooled RR was 1.41 for all case-control studies. The RRs were 3.27 in case-control studies of silicotics only, 1.41 in studies where silicosis status was undefined and 0.97 among non silicotic subjects. The RR was 1.24 for PMR studies.
In this re-analysis, the association with lung cancer was consistent for silicotics, but the data were limited for non silicotic subjects and not easily explained for undefined silicosis status workers. This leaves open the issue of dose-risk relation and pathogenic mechanisms and supports the conclusion that the carcinogenic role of silica per se in absence of silicosis is still unclear.
To expand on the limited size and scope of construction silica exposure studies, a silica monitoring data compilation project was initiated through the American Conference of Governmental Industrial Hygienists Construction Committee. Personal silica exposure monitoring data was collected and analyzed from 13 private, research, and regulatory groups. An effort was made to collect as much detail as possible about task, tool, and environmental and control conditions so as much information as possible could be garnered. There were considerable data gaps, particularly with regulatory agency data, that represented over half of the data set. There were 1374 personal quartz samples reported with a geometric mean of 0.13 mg/m(3) and a GSD of 5.9. Descriptive statistics are reported by trade, task, tool, and data source type. Highest exposures were for abrasive blasters, surface and tuckpoint grinders, jackhammers, and rock drills. The sample period was important, with short-term samples (up to 2 hours) having considerably higher levels than midterm (2-6 hours) or longer (over 6 hours) samples. For nearly all exposure variables, a large portion of variable categories were at or over the quartz occupational exposure limit of 0.05 mg/m(3), including 8 of 8 trade, 13 of 16 task, and 12 of 16 tool categories. The respiratory protection commonly used on construction sites is often inadequate for the exposures encountered. The data variability within task and tool was very large, with some very high exposures reported for a broad spectrum of tools. Further understanding of the conditions leading to high exposures will require more detailed documentation of the sample characteristics following database design recommendations or systematic surveys of exposure in this complex industry.
Objective: The aim of the study is to evaluate fiberoptic bronchoscopic signs especially in mine workers with progressive massif fibrosis (PMF) during diagnostic work-up. Material and methods: We evaluated clinical examination, radiological and bronchoscopic data of 22 patients who had worked in coal mines between 2003 and 2006. Results: Medical files of 22 male patients aged between 43 and 83 with a mean age of 66.4±9.37 years were investigated. Fifteen (68.2 %) were smokers. Duration of coal mine exposure was 2I.5±9 years. Six (27.3 %) patients were asymptomatic and the others had mainly coughs, expectoration of sputum and dyspnea. The radiological signs were as follows: PMF (n:22;100 %),fibrotic pattern (n:21;95.4 %), reticular nodules (n:20;90 %), micronodutes (n:17;77.2 %). calsificated hilus node (n:17;77.2 %), interstitial pattern (n:16;72.7 %), pleural thickening (n:16;72.7 %), macro nodules (n:15;68.1 %), bullae and emphysematous areas (n:9;40.9 %), pleural calsi-fications (n:6;27.2 %), and alveolar opacities (n:4;18.1 %). The bronchoscopic signs were bronchial stenosis (77.2 %), scar antracotic deformity of bronchi (72.7 %), diffuse atrophy and pale bronchial mucosa (63.6 %), antracotic plaques (63.6 %), diffuse bronchial inflammatory appearance (50 %), enlarged main and/or lobe carina (40.9 %), black-gray sputum (13.6 %), and bronchial mucosa atrophy (4.5 %). Conclusion: You should keep in mind that during diagnostic work-up of mine workers with PMF, indirect tumor signs can be detected during broncoshoscopic procedures..
The term ‘pneumoconiosis’ is used to describe pulmonary diseases associated with dust inhalation. It is normally used in the context of coal-worker's pneumoconiosis, but many other dusts can cause the dext of coal-worker's pneumoconiosis, but many other dusts can cause the disease. This contribution focuses on the major causes of pneumoconiosis in the UK (coal-worker's pneumoconiosis and silicosis).The site of damage (if any) within the lung is a function of both the size and the toxicity of the inhaled particles. Generally, particles with a median diameter of 0.5-10 μm can penetrate the alveoli, and those that are toxic to host cells (particularly macrophages) can cause permanent harm. Many mechanisms are likely to be particle specific; in general, however, release of pro-inflammatory cytokines (initially from alveolar macrophages) causes fibroblast formation and eventual fibrosis. The propensity of different types of particles to cause fibrosis varies widely; for example, silica dust is highly fibrogenic, whereas iron dust is not.
Numerous research articles dealing with Respirable Crystalline Silica (RCS) in occupational health because epidemiological studies reveal an association between RCS-dust and the development of silicosis as well as an increased probability of developing lung cancer. Research activities about RCS in ambient air are known from US-measurements. However there is a lack of knowledge regarding RCS-emissions in several industrial sectors. Industrial sources of crystalline silica include construction, foundries, glass manufacturing, abrasive blasting or any industrial or commercial use of silica sand, and mining and rock crushing operations. This paper describes a RCS-emission measurement method for stack gases and report results from the German RCS-emission measurement programmes which were used to identify installations and types of industries with the highest concentration levels of RCS in stack gases. A two-stage cascade impactor was used for the measurements which separate particles into the following size fractions: >10 μm, 10–4 μm und <4 μm of aerodynamic diameter. The measurements were carried out according to international sampling standards. The size of crystalline silica particles of most concern are those respirable particles that are smaller than four microns (millionths of a metre), also called particulate matter 4 (PM4). The analytical procedure of determining crystalline silica in emission samples (in the fraction below 4 μm) consists of using x-ray diffraction and infrared spectroscopy methods which are the same methods as used in the field of occupational health. A total of 37 emission measurement campaigns were assessed (112 RCS-samples in nine industrial sectors). The investigated plants are located in different German states such as Bavaria, North Rhine Westphalia, Baden-Wuerttemberg, Rhineland-Palatinate and Saxony-Anhalt. The results of the measurements show that most of the investigated plants can achieve compliance with the newly developed German emission limit value (ELV) of 1 mg m−3. The ELV is expressed as the concentration of RCS in stack emissions. According to the German emission minimising principle and the precautionary principle it is assumed that by complying with the RCS-ELV there is no ambient air health risk for people living these plants. In the case of increased total dust concentration in the stack gas (more than 20 mg m−3) combined with increased percentage of crystalline silica in PM4 dust, a violation of the above mentioned ELV is more likely. This applies mostly to installations in the silica sand processing industry. To comply with the ELV of 1 mg m−3, efficient emission control technology should be implemented and should be well maintained.
The aims of this study in a nonferrous foundry were to determine if the silica content was identical when simultaneous area total and respirable dust air sampling was conducted; to define the relationship between personal respirable and total dust concentrations on the same person; and to assess if these relationships changed with job descriptions where silica exposures were likely. Respirable dust air samples in the shakeout and core-knockout areas mostly showed enrichment in silica content relative to total dust air samples obtained simultaneously in the same area. The fraction of respirable dust relative to total dust in the air in personal samples increased for the following job descriptions: basement reclamation (4.4%) < molding (14%) ≤ core-knockout (18%) ≤ shakeout (23%). Absolute levels of respirable dust in the air were about the same over all work areas in spite of much higher total dust concentrations in the basement reclamation area. The silica content of bulk samples did not predict the silica content for total or respirable dust area air samples. There was a negative bias relative to the area sample data of Verma for the shakeout area. The relationships for different job descriptions varied markedly.
A preliminary study of personal exposure to respirable quartz was conducted in four shops that used a variety of wet and dry methods to fabricate countertops from granite and quartz-containing synthetic stone-like materials. Full-shift time-weighted average (TWA) exposures exceeded the ACGIH threshold limit value of 0.025 mg/m(3) for all workers who used dry fabrication methods, even for very limited time, during any part of the work shift (n = 15 person-days). The geometric mean of exposures for workers who used dry methods extensively was about 1 mg/m(3) (n = 12 person-days). Workers who operated only automated or remotely controlled stone cutting or shaping equipment had calculated TWA exposures of approximately 0.02 mg/m(3) (n = 3 person-days). Task-specific geometric mean exposures for various wet and dry manual operations were ranked based on estimated concentrations extracted from multi-task partial-shift sample results using a linear algebra procedure. Limited use of dry methods was observed in shops that had previously reported using only wet methods. These results suggest that even shops that report using only wet methods might, in fact, resort to brief use of dry methods for specific operations. Therefore, there may be reason for concern over potential overexposure to respirable quartz in all stone countertop shops.
In the attempt to estimate the average concentration of a particular contaminant during some period of time, a certain proportion of the collected samples is often reported to be below the limit of detection. The statistical terminology for these results is known as censored data, i.e., nonzero values which cannot be measured but are known to be below some threshold.Samples taken over time are assumed to follow a lognormal distribution. Given this assumption, several techniques are presented for estimation of the average concentration from data containing nondetectable values. The techniques proposed include three methods of estimation with a left-censored lognormal distribution: a maximum likelihood statistical method and two methods involving the limit of detection. Each method is evaluated using computer simulation with respect to the bias associated with estimation of the mean and standard deviation. The maximum likelihood method was shown to produce unbiased estimates of both the mean and standard deviation under a variety of conditions. However, this method is somewhat complex and involves laborious calculations and use of tables. Two simpler alternatives involve the substitution of L/2 and a new proposal of L/2 for each nondetectable value, where L = the limit of detection. The new method was shown to provide more accurate estimation of the mean and standard deviation than the L/2 method when the data are not highly skewed. The L/2 method should be used when the data are highly skewed (geometric standard deviation [GSD] approximately 3.0 or greater)
From 1979 to 1982, the National Institute for Occupational Safety and Health (NIOSH) conducted a cross-sectional exposure assessment and mortality study of selected crushed stone facilities in the United States. This study was undertaken in part to address concerns that asbestos exposures could be occurring in some crushed stone operations due to the presence of amphibole and serpentine minerals. The investigation was also designed to characterize exposures to crystalline silica and other mineral compounds. Nineteen crushed stone operations, mining limestone, granite, or traprock were surveyed to assess exposures to respirable and total dusts, mineral compounds including crystalline silica, asbestos, and mineral fibers. At the initiation of the study, crushed stone operations were selected from a Mine Safety and Health Administration (MSHA) listing of the active industry in 1978. With the exception of requiring inclusion of the traprock operation in Maryland where asbestos fibers were initially discovered, a stratified sample of operations was randomly selected by rock type (granite, limestone, traprock, or sandstone). However, because of reluctance or refusal of some companies to participate and because of the closures of some of the selected operations, replacements were randomly selected. Some replacement selections were likewise replaced due to lack of cooperation from the companies. The studied sample included only 10 of the 27 randomly selected operations in the original sample. Asbestos fibers were detected at one traprock facility, the Maryland operation where asbestos was originally found. Measured personal exposures to fibers exceeded the NIOSH Recommended Exposure Limit (REL) for two out of 10 samples. All of the samples were below the MSHA Permissible Exposure Limit (PEL), which was in effect at the time of the survey. However, due to the presence of nonasbestos mineral fibers in the environment, it could not be stated with certainty that all of the fibers counted by phase contrast microscopy were asbestos. A variety of silicate mineral fibers (other than those classified by NIOSH as asbestos) were detected in the traprock operations and at one granite operation. Crystalline silica was detected at 17 of the 19 surveyed crushed stone operations. Overexposures to crystalline silica were measured at 16 of the crushed stone operations; approximately one in seven personal-respirable dust samples (14%) exceeded the MSHA PEL for crystalline silica. Approximately 25% of the respirable dust samples exceeded the NIOSH REL for crystalline silica. Mill operators and mill laborers consistently had the highest and most frequent overexposures to crystalline silica.
Besides a clear relationship to silicosis, crystalline silica—quartz—has been associated with lung cancer, nonmalignant renal disease, and auto-immune disease. To study diseases associated with crystalline silica further, NIOSH conducted a cohort mortality study of workers from 18 silica sand plants, which had quarry, crushing, and bagging operations to produce industrial sand. Twelve of these plants also had grinding mills to produce fine silica powder. The historical crystalline silica exposures of workers at these plants were estimated to facilitate exposure–response analyses in the epidemiologic study.
Silicosis is a fibrotic lung disease caused by inhalation of free crystalline silicon dioxide or silica. Occupational exposure to respirable crystalline silica dust particles occurs in many industries. Phagocytosis of crystalline silica in the lung causes lysosomal damage, activating the NALP3 inflammasome and triggering the inflammatory cascade with subsequent fibrosis. Impairment of lung function increases with disease progression, even after the patient is no longer exposed. Diagnosis of silicosis needs carefully documented records of occupational exposure and radiological features, with exclusion of other competing diagnoses. Mycobacterial diseases, airway obstruction, and lung cancer are associated with silica dust exposure. As yet, no curative treatment exists, but comprehensive management strategies help to improve quality of life and slow deterioration. Further efforts are needed for recognition and control of silica hazards, especially in developing countries.
The risk of developing clinical connective tissue disease (CTD) has been reported to be increased among individuals with silica exposure.
We reviewed the medical records of individuals reported to the Michigan Silicosis Surveillance system from 1985 to 2006 to confirm the diagnosis of silicosis and determine the presence of CTDs.
From 1985 to 2006, 1,022 cases were confirmed to have silicosis. Medical records of 790 cases were available. Thirty-three individuals had rheumatoid arthritis (RA) [prevalence 4.2% (prevalence ratio (RR) ranged from 2.26, 95% CI: 1.57-3.25 to 6.96, 95% CI: 2.93-16.53) depending on the reference rate used], two had scleroderma [prevalence 0.3% (RR 28.3, 95% CI: 6.09-129.98)], one had systemic lupus erythematosus [prevalence 0.1% (RR 2.53, 95% CI: 0.30-21.64)], two had Sjogrens syndrome [prevalence 0.3% (RR 0.42, 95% CI: 0.09-2.08)], and six had anti-neutrophil cytoplasm antibody (ANCA) vasculitis [prevalence 0.8% (RR 25.3, 95% CI: 6.34-101.04)]. There was no difference between those with and without CTD with respect to age, race, industry type, history of tuberculosis, application for workers' compensation, or severity of fibrotic changes on chest X-ray.
A two- to eightfold risk for RA and systemic lupus erythematosus, with a greater than 24-fold risk for scleroderma and ANCA vasculitis was found in individuals with silicosis. The most common CTD among silicotics in the Michigan disease registry was RA. Though not classically included in the category of CTD, ANCA-associated vasculitis was found to have a much greater prevalence amongst silicosis patients than the general population.
Sumario: Inhalable dust, total dust and respirable dust by cyclone and horizontal elutriator were measured in a side area sampling programme at eight selected ferrous and non-ferrous foundries. Forty sets of samples were collected and the relatioships between four different dust measurements were examined. In the foundry environments sruveyed, total dust correlated highly with the inhalable dust concentration. The MRE elutriator operating at 2.5 l. min-1 flow rate, matching the BMRC respirable dust criterion, generally collected more dust by weight per m3 air than the 10 mm nylon cyclone, operating at 1.7 l. min-1 matching the ACGIH respirable dust criterion
Dust measurements were made in 51 iron, 9 steel, and 8 nonferrous foundries, at which 4,316 foundrymen were working. The sampling lasted at least two entire shifts or work days continuously during various operations in each foundry. The dust samples were collected at fixed sites or in the breathing zones of the workers. The mass concentration was determined by weighing and the respirable dust fraction was separated by liquid sedimentation. The free silica content was determined by X-ray diffraction. In the study a total of 3,188 samples were collected in the foundries and 6,505 determinations were made in the laboratory. The results indicated a definite difference in the dust exposure during various operations. The highest dust exposures were found during furnace, cupola, and pouring ladle repair. During cleaning work, sand mixing, and shake-out operations excessive silica dust concentrations were also measured. The lowest dust concentrations were measured during melting and pouring operations. Moderate dust concentrations were measured during coremaking and molding operations. The results obtained during the same operations of iron and steel foundries were similar. The distribution of the workers into various exposure categories, the content of respirable dust and quartz, the correlation between respirable dust and total dust, and the correlation between respirable silica and total dust concentrations are discussed. Observations concerning dust suppression and control methods are briefly considered.
From 1979 to 1982, the National Institute for Occupational Safety and Health (NIOSH) conducted a cross-sectional exposure assessment and mortality study of selected crushed stone facilities in the United States. This study was undertaken in part to address concerns that asbestos exposures could be occurring in some crushed stone operations due to the presence of amphibole and serpentine minerals. The investigation was also designed to characterize exposures to crystalline silica and other mineral compounds. Nineteen crushed stone operations, mining limestone, granite, or traprock were surveyed to assess exposures to respirable and total dusts, mineral compounds including crystalline silica, asbestos, and mineral fibers. At the initiation of the study, crushed stone operations were selected from a Mine Safety and Health Administration (MSHA) listing of the active industry in 1978. With the exception of requiring inclusion of the traprock operation in Maryland where asbestos fibers were initially discovered, a stratified sample of operations was randomly selected by rock type (granite, limestone, traprock, or sandstone). However, because of reluctance or refusal of some companies to participate and because of the closures of some of the selected operations, replacements were randomly selected. Some replacement selections were likewise replaced due to lack of cooperation from the companies. The studied sample included only 10 of the 27 randomly selected operations in the original sample. Asbestos fibers were detected at one traprock facility, the Maryland operation where asbestos was originally found. Measured personal exposures to fibers exceeded the NIOSH Recommended Exposure Limit (REL) for two out of 10 samples. All of the samples were below the MSHA Permissible Exposure Limit (PEL), which was in effect at the time of the survey. However, due to the presence of nonasbestos mineral fibers in the environment, it could not be stated with certainty that all of the fibers counted by phase contrast microscopy were asbestos. A variety of silicate mineral fibers (other than those classified by NIOSH as asbestos) were detected in the traprock operations and at one granite operation. Crystalline silica was detected at 17 of the 19 surveyed crushed stone operations. Overexposures to crystalline silica were measured at 16 of the crushed stone operations; approximately one in seven personal-respirable dust samples (14%) exceeded the MSHA PEL for crystalline silica. Approximately 25% of the respirable dust samples exceeded the NIOSH REL for crystalline silica. Mill operators and mill laborers consistently had the highest and most frequent overexposures to crystalline silica.
Between 1980 and 1992, compliance officers of the Occupational Safety and Health Administration in the United States measured respirable quartz in 1655 inspections in 255 industries. In 52% of the 255 industries where respirable quartz was measured, the average severity value was less than one, indicating average exposures below the permissible exposure limit, and in 48% the permissible exposure limit for silica was exceeded. Among industries where more than 10 facilities were inspected, the most severe respirable quartz exposures were found in fabricated structural metal; painting and paper hanging; nonresidential construction; shipbuilding and repair; masonry and other stone work; bridge, tunnel and elevated highway construction; metal coating, engraving and allied services; and special trades contractors.
The relationship between crystalline silica and lung cancer has been the subject of many recent publications, conferences, and regulatory considerations. An influential, international body has determined that there was sufficient evidence to conclude that quartz and cristobalite are carcinogenic in humans. The present authors believe that the results of these studies are inconsistent and, when positive, only weakly positive. Other, methodologically strong, negative studies have not been considered, and several studies viewed as providing evidence supporting the carcinogenicity of silica have significant methodological weaknesses. Silica is not directly genotoxic and is a pulmonary carcinogen only in the rat, a species that seems to be inappropriate for assessing particulate carcinogenesis in humans. Data on humans demonstrate a lack of association between lung cancer and exposure to crystalline silica. Exposure-response relationships have generally not been found. Studies in which silicotic patients were not identified from compensation registries and in which enumeration was complete did not support a causal association between silicosis and lung cancer, which further argues against the carcinogenicity of crystalline silica.
Besides a clear relationship to silicosis, crystalline silica-quartz-has been associated with lung cancer, nonmalignant renal disease, and auto-immune disease. To study diseases associated with crystalline silica further, NIOSH conducted a cohort mortality study of workers from 18 silica sand plants, which had quarry, crushing, and bagging operations to produce industrial sand. Twelve of these plants also had grinding mills to produce fine silica powder. The historical crystalline silica exposures of workers at these plants were estimated to facilitate exposure-response analyses in the epidemiologic study.
NIOSH obtained personal respirable dust measurement records from Mine Safety and Health Administration (MSHA) compliance inspections at all 18 plants and from the archives of seven plants which had collected samples. These samples had been analyzed for quartz content by x-ray diffraction. Although no personal samples were available before 1974, impinger dust measurements were reported for 19 silica sand plants in 1946; these data were converted and used to estimate exposures prior to 1974. Statistical modeling of the samples was used to estimate quartz exposure concentrations for workers in plant-job-year categories from the 1930s when mortality follow-up of the cohort began until 1988 when follow-up stopped.
Between 1974 and 1996, there were 4,269 respirable dust samples collected at these 18 plants. The geometric mean quartz concentration was 25.9 microg/m(3) (GSD = 10.9) with a range from less than 1 to 11,700 microg/m(3). Samples below 1 microg/m(3) were given a value of 0.5 microg/m(3). Over one-third of the samples -37%) exceeded the MSHA permissible exposure limit value for quartz (PEL = 10 mg/m(3)/(%quartz + 2)) and half (51%) of the samples exceeded the NIOSH recommended exposure limit (REL=50 microg/m(3)). The samples were collected from workers performing 143 jobs within the 18 plants, but too few samples were collected from many of the jobs to make accurate estimates. Therefore, samples were combined into 10 categories of jobs performing similar tasks or located within the same plant area.
The quartz concentrations varied significantly by plant, job, and year. Quartz concentrations decreased over time, with measurements collected in the 1970s significantly greater than those collected later. The modeled exposure estimates improve upon duration of employment as an estimate of cumulative exposure and reduce exposure misclassification due to variation in quartz levels between plants, jobs, and over time. Am. J. Ind. Med. 38:389-398, 2000. Published 2000 Wiley-Liss, Inc.
Autoimmune diseases are pathologic conditions defined by abnormal autoimmune responses and characterized by immune system reactivity in the form of autoantibodies and T cell responses to self-structures. Here we review the limited but growing epidemiologic and experimental literature pertaining to the association between autoimmune diseases and occupational exposure to silica, solvents, pesticides, and ultraviolet radiation. The strongest associations (i.e., relative risks of 3.0 and higher) have been documented in investigations of silica dust and rheumatoid arthritis, lupus, scleroderma and glomerulonephritis. Weaker associations are seen, however, for solvent exposures (in scleroderma, undifferentiated connective tissue disease, and multiple sclerosis) and for farming or pesticide exposures (in rheumatoid arthritis). Experimental studies suggest two different effects of these exposures: an enhanced proinflammatory (TH1) response (e.g., TNF-alpha and IL-1 cytokine production with T cell activation), and increased apoptosis of lymphocytes leading to exposure to or modification of endogenous proteins and subsequent autoantibody formation. The former is a general mechanism that may be relevant across a spectrum of autoimmune diseases, whereas the latter may be a mechanism more specific to particular diseases (e.g., ultraviolet radiation, Ro autoantibodies, and lupus). Occupational exposures are important risk factors for some autoimmune diseases, but improved exposure assessment methods and better coordination between experimental/animal models and epidemiologic studies are needed to define these risks more precisely.
While silica particles are considered to be fibrogenic and carcinogenic agents, the mechanisms responsible are not well understood. This article summarizes literature on silica-induced accelerated silicosis, chronic silicosis, silico-tuberculosis, bronchogenic carcinoma, and immune-mediated diseases. This article also discusses the generation of reactive oxygen species (ROS) that occurs directly from the interaction of silica with aqueous medium and from silica-stimulated cells, the molecular mechanisms of silica-induced lung injuries with focus on silica-induced NF-kappaB activation, including its mechanisms, possible attenuation and relationship to silica-induced generation of cyclooxygenase II and TNF-alpha. Silica-induced AP-1 activation, protooncogene expression, and the role of ROS in these processes are also briefly discussed.
Recent studies of the size and composition of atmospheric particulate matter (PM) have demonstrated the usefulness of separating atmospheric PM into its fine and coarse components. The need to measure the mass and composition of fine and coarse PM separately has been emphasized by research in exposure, epidemiology, and toxicology of atmospheric PM. This paper provides a background on the size distribution and properties of PM relevant to the differences between fine and coarse particles. Various decisions that must be made when deciding how to separate, collect, and measure PM are discussed. Techniques for monitoring fine and coarse particles, including the US Federal Reference Method for PM2.5 and several techniques for PM10-2.5, are presented. Problems encountered in collecting semivolatile PM and in weighing atmospheric PM collected on a filter are described. Continuous monitoring methods for PM mass and for PM components (carbon, nitrate, and sulfate) are described and brief descriptions are given of analytical techniques for the chemical characterization of collected PM. This information should be especially useful for environmental workers familiar with monitoring methods for total suspended particles or PM10 but who will need to measure PM2, and PM10-2.5 in the future.
Occupational interstitial lung diseases are a diverse group of disorders of varied cause. Occupational causes account for a significant portion of all interstitial lung diseases, and new causes continue to be described. Although some are diseases of antiquity, they continue to occur in the workplace and often are misdiagnosed as "idiopathic" when physicians miss the connection to past-inhaled exposures. All of these diseases are preventable with reduction or elimination of workplace exposure. This article reviews the spectrum of diseases caused by exposure to metal dust and fumes, inorganic fibers, and nonfibrous inorganic dust. It also details an approach to the diagnosis, evaluation, and management of this group of illnesses.
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.
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.
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.
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.
Known dust control methods should be implemented and regular medical surveillance should be provided.
Occupational Health and Safety Code under the Occupational Health and Safety Act RSO
- Alberta 16 Government
- Carex
- Canada
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Prevalence of connective tissue disease in silicosis
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- M J Reilly
Makol, A., M.J. Reilly, and K.D. Rosenman: Prevalence of connective tissue disease in silicosis (1985–2006)
Pneumoconiosis, systemic and parenchymal lung diseases
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Fishwick, D.: Pneumoconiosis, systemic and parenchymal lung diseases. Medicine 36(5):258–261 (2008).
Rock: Strategy for Occupa-tional Exposure Assessments
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Germolec: Occupational expo-sure and autoimmune diseases
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- F W Miller
Cooper, G.S., F.W. Miller, and D.R. Germolec: Occupational expo-sure and autoimmune diseases. Intern. Immunopharmacol. 2:303–3013 (2002).
Construction Workers' Exposure to Crystalline Silica -Literature Review and Analysis, Studies and Research Projects
- C Beaudry
- C Dion
- M Gé
- G Perrault
- D Bé
- J Lavoué
Beaudry, C., C. Dion, M. Gé, G. Perrault, D. Bé, and J. Lavoué: Construction Workers' Exposure to Crystalline Silica -Literature Review and Analysis, Studies and Research Projects (Report R-771). Montré: Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST) (2013).