Association between Crystalline Silica Dust Exposure and Silicosis Development in Artificial Stone Workers

Issue 3-The occupational burden of respiratory diseases, an update

INTRODUCTION AND AIMS

Workplace exposures are widely known to cause specific occupational diseases such as silicosis and asbestosis, but they also can contribute substantially to causation of common respiratory diseases. In 2019, the American Thoracic Society (ATS) and the European Respiratory Society (ERS) published a joint statement on the occupational burden of respiratory diseases. Our aim on this narrative review is to summarise the most recent evidence published after the ATS/ERS statement as well as to provide information on traditional occupational lung diseases that can be useful for clinicians and researchers.

RESULTS

Newer publications confirm the findings of the ATS/ERS statement on the role of workplace exposure in contributing to the aetiology of the respiratory diseases considered in this review (asthma, COPD, chronic bronchitis, idiopathic pulmonary fibrosis, hypersensitivity pneumonitis, infectious pneumonia). Except for COPD, chronic bronchitis and infectious pneumonia, the number of publications in the last 5 years for the other diseases is limited. For traditional occupational lung diseases such as silicosis and asbestosis, there are old as well as novel sources of exposure and their burden continues to be relevant, especially in developing countries.

CONCLUSIONS

Occupational exposure remains an important risk factor for airways and interstitial lung diseases, causing occupational lung diseases and contributing substantially in the aetiology of common respiratory diseases. This information is critical for public health professionals formulating effective preventive strategies but also for clinicians in patient care. Effective action requires shared knowledge among clinicians, researchers, public health professionals, and policy makers.

Global scenario of silica-associated diseases: A review on emerging pathophysiology of silicosis and potential therapeutic regimes

Silicosis is an occupational fibrotic lung disease caused by exposure to respirable crystalline silica dust particles produced during industrial activities. Other crystalline silica-induced pulmonary disorders include a predisposition to mycobacterial infections, obstructive airway diseases, idiopathic pulmonary fibrosis, and lung cancer. This review paper discusses the burden of silicosis and associated co-morbidities in developed as well as developing countries globally using the published data of various government agencies, related organizations, and epidemiological findings. Moreover, it sheds light on diverse mechanisms of silicosis, outlining molecular events and peculiar alterations in lung parenchyma leading to this occupational lung disease. Evaluation of pathophysiological mechanisms could aid in the identification of novel target molecules and treatments; to date, there is no curative treatment for silicosis. In recent periods, a lot of attention has been focused on the development and fabrication of suitable nanocarriers for improved and sustained drug delivery in the pulmonary system. Nanoparticle-based therapeutic modality has been evaluated in in-vitro and ex-vivo silicosis models for prolongation of drug activity and improved therapeutic outcomes. The preclinical findings open the doors to clinical trials for operational and regenerative nanoformulations, which eventually create a positive change in medical practice. The following review summarizes various therapeutic approaches available and in the pipe line for silicosis and also stresses the preventive practices for effectively combating this occupational hazard.

PM10-bound elements in Luanda's urban atmosphere: Concentrations, sources, and their environmental and health impacts

An unprecedented study was carried out in the megacity of Luanda, Angola, involving daily sampling of particulate matter (PM10) from June to November 2023. The analysis was focused on the detection of 56 metal(loid)s and complemented by the application of several contamination and health risk indices. PM10 levels ranged from 23.6 to 108 μg/m3, averaging 59.3 μg/m3, exceeding WHO's 24-h guideline on 83% of days. In addition to crustal elements, the most abundant constituents were Zn (159 ng/m3), Ba (43.2 ng/m3), Pb (17.8 ng/m3), Cu (10.5 ng/m3), Sr (7.0 ng/m3), Ni (4.5 ng/m3), Sb (3.7 ng/m3) and Cr (3.5 ng/m3). Mineral dust, primarily from unpaved roads and local soils, accounted for 31 wt% of PM10, while sea salt contributed 6%. Geochemical markers (e.g., Ce-La-V relationships) suggest that vanadium originates predominantly from upper crust weathering. Elemental ratios such as Fe/Cu, Cu/Sb, and Zn/Sb indicate significant contributions from traffic-related emissions (e.g., brake and tyre wear) and industrial sources. Sulphur, an important PM10 component, likely stems from fossil fuel combustion and petroleum refining. Luanda experiences severe air pollution, with high inputs from Sb, Cd, Zn, and other elements linked to traffic, industrial emissions, and biomass burning. The extremely high ecological risk (RI = 4360 ± 2440) highlights critical contamination, driven primarily by Cd and Sb, while the Nemerow risk index (1990 ± 1530) underscores urgent public health concerns. Non-cancer hazard indices (HI) exceeded safe thresholds for children (2.29) and adults (2.18), with Fe, Mn, Be, Pb, Ni, Co, and Sb identified as key contributors. Carcinogenic risks from PM10 inhalation (2.34 × 10-3 for children and 1.36 × 10-3 for adults) also exceeded acceptable levels, emphasising the need for targeted pollution mitigation strategies.

The Banning of Engineered Stone in Australia: An Evidence-Based and Precautionary Policy

On December 13, 2023, Australia became the first country to ban engineered stone. This material contains more than 80 percent crystalline silica, agglomerated with resins, metal oxides and other (potentially toxic) substances. Engineered stone has become a mass-market product since the late 1990s and has contributed to a worldwide resurgence of accelerated forms of silicosis and a notable incidence of systemic diseases. Such a ban is a very rare event in a world where the regulatory framework governing the use of toxic substances in the workplace is generally limited to setting exposure limits. The Australian decision is exemplary in many respects: it is based on public consultation with all stakeholders, it contributes to updating biomedical knowledge that industries seek to conceal or undermine, and it is based on a realistic vision of real working conditions. In the absence of any evidence that lowering the silica content of this material would reduce occupational hazards related to toxic cocktail effects, this ban implements an evidence-based and precautionary public health policy.

Measuring improvements in occupational health and safety in the artificial stone benchtop industry

OBJECTIVES

Workers in the stone benchtop industry in Australia are at high risk of silicosis due to exposure to respirable crystalline silica (RCS) from the dry processing of artificial stone. In Victoria, Australia, a multifaceted response including education, regulatory changes, inspection site visits, and occupational health screening programme began in 2019. We aimed to review the success of this approach to safety practices in the industry.

METHODS

Data were available from 2 sources: first, responses provided by workers during their occupational health screening (2019 to 2024), which included a systematic occupational history. Jobs examined included roles in the stone benchtop industry with RCS exposure and were analysed in relation to reported safety practices pre and postregulatory changes in August 2019, which prohibited unrestricted dry cutting. Second, data were obtained from the Regulator describing the numbers of visits to industry worksites and the numbers and types of compliance notices issued between 2018 and 2024.

RESULTS

In total, 1921 jobs from 1007 workers were eligible for analysis, of which 869 were prior to the 2019 regulatory change and 557 commenced after. The proportion of workers reporting "never" dry cutting rose from 17.3% to 67.2% (P < 0.001), use of recommended ventilation and respirator increased from 26.0% to 36.5% (P < 0.001), and 44.9% to 86.5% (P < 0.001), respectively. Of the 543 worksites visited (2757 site visits in total), 352 (64.8%) received at least one compliance notice and the types of notices varied over time. Administrative controls/housekeeping and health monitoring notices were the most common in 2019 to 2021 but tools/equipment notices increased substantially in 2022 onwards.

DISCUSSION

Prior to the changes, a large proportion of jobs involved unrestricted dry processing of artificial stone with inadequate protection. After the changes, practices improved although some jobs continued to involve dry processing without adequate control of dust.

CONCLUSIONS

This multifaceted approach vastly improved safety practices in the stone benchtop industry over 5 years. These data are relevant to occupational health and safety professionals and regulators in countries where artificial stone is used and potentially for implementation of new measures in response to a new workplace hazard in future.

Release of Crystalline Silica Nanoparticles during Engineered Stone Fabrication

Inhalation exposure to respirable crystalline silica (RCS) during the fabrication of engineered stone-based kitchen countertops has been on the rise in recent years and has become a significant occupational health problem in the United States and globally. Little is known about the presence of nanocrystalline silica (NCS), i.e., particles below 100 nm. We present a methodology to quantify the crystalline silica content in the sub-100 nm size fraction of the aerosol released during engineered stone fabrication using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. Aerosol was generated in a test chamber designed per EN 1093-3 and sampled using cascade impactors. XRD and FTIR analysis showed the presence of both α-quartz (15-60%) and cristobalite (10-50%) polymorphs in all size fractions. With increasing particle size, the cristobalite content increased. Seventy percent of the total aerosol mass in the sub-100 nm fraction was found to be crystalline silica, qualitatively confirmed by electron diffraction and electron energy loss spectroscopy. The presence of other minerals was detected in all size fractions; no polymeric resin binder was detected in the sub-100 nm fraction. Although the sub-100 nm fraction was about 1% of the aerosol mass, it accounted for 4-24% of the aerosol surface area based on the total lung deposition. If the surface area is a more relevant exposure metric, the assessment of the efficacy of current engineering control systems using mass as an exposure metric may not provide adequate protection.

Silicosis Incidence and Mortality after Occupational Exposure with Silica Dust: A Systematic Review and Dose-Response Meta-Analysis

Background

We conducted a systematic review of all published epidemiological research related to the relationship between occupational silica exposure and the rates of silicosis incidence and mortality.

Methods

We searched Scopus, PubMed, and Web of Sciences up to 11/07/2023, for original in any language. The search start date was not limited Observational studies, including cohort, case-control, and cross-sectional that have reported risk estimates for the association between silica exposure and silicosis mortality and incidence rates were considered. The methodological quality of the included articles was assessed using the Newcastle-Ottawa scale. Pooled estimates were calculated using the random effects model. Dose-response relations were explored through a two-stage random-effects model with "drmeta" command in Stata software version 14.

Results

Nineteen observational studies were included in the present systematic review and meta-analysis. Based on the linear dose-response analysis, with each mg/m3 increase in daily occupational exposure to silica, the mortality risk of silicosis, the odds and risk of silicosis occurrence significantly increased by 10.19%, 360.02%, and 4.43 × 108%, respectively.

Conclusion

This review revealed that there is a linear dose-response relationship between occupational exposure to silica and incidence and mortality from silicosis. Our findings could have practical applications for occupational and public health. Considering the direct relationship between occupational silica exposure and high incidence and mortality rates of silicosis, the level of silica dust should be decreased in different industries.

Development of rapid prediction model for silicosis risk among stone carvers in Nakhon Ratchasima, Thailand

Exposure to silica dust presents a risk for the development of lung disease for stone carvers in Nakhon Ratchasima province, Thailand. This study aimed to develop a rapid prediction model for the assessment of silicosis risk among 243 stone carvers who were exposed to silica at work from August and October 2023 in Nakhon Ratchasima, Thailand. Demographic characteristics collected in questionnaires were work information; basic health information; health behavior data, including prevention and control of silicosis; knowledge; attitude; and practices for surveillance, prevention, and control of silicosis. Respirable crystalline silica (RCS) exposures were measured by conducting personal air sampling. Risk scores of silicosis were calculated and a rapid prediction model for assessment of silicosis risk among stone carvers was determined. It was found that 11 variables were significantly associated with silicosis risk scores (p < 0.05). However, it was demonstrated that only four significant influential variables, including the concentration of silica dust exposure (mg/m3), working hours per day, underlying diseases, and separation of residence from a workplace were acceptable for conducting a silicosis risk assessment using multiple regression analysis (R2 = 0.675). This study indicated that a prediction model can be used for the assessment of silicosis risk among stone carvers. Therefore, the use of this prediction model is recommended to evaluate the risk associated with exposure to RCS of stone carvers in Nakhon Ratchasima province, Thailand due to its simplicity, accuracy, and time-saving attributes.

Exosomal proteomics and cytokine analysis distinguish silicosis cases from controls

Occupational silica exposure caused a serious disease burden of silicosis. There is currently a lack of sensitive and effective biomarkers for silicosis, and the pathogenesis of silicosis is unclear. Exosomes were significant in the pathogenesis of silicosis, and our study was carried out from exosomal proteomics and cytokine analysis. Firstly, the plasma levels of cytokines were detected using a Luminex multiplex assay, and the results indicated that the plasma levels of TNF-α, IL-6, CCL2, CXCL10, and PDGF-AB were significantly higher in silicosis patients than in silica-exposed workers and controls (p < 0.05). After correlation analysis, the plasma levels of cytokines were positively correlated with exosomal protein concentration. Secondly, data-independent acquisition (DIA) was performed on plasma-derived exosomes in the screening population, which identified 88, 151, 293, and 53 differentially expressed proteins (DEPs) in exposure/control, silicosis/control, silicosis/exposure, and silicosis stage Ⅲ/silicosis stage Ⅰ groups respectively. After parallel reaction monitoring (PRM) in an independent verification population, the results indicated that the changing trend of 15 DEPs was coincident in screening and verification results. The result of correlation analysis indicated that the plasma level of TNF-α was negatively correlated with the expression of exosomal DSP, KRT78, SERPINB12, and CALML5. The AUC of combined determination of TNF-α and CALML5 reached 0.900, with a sensitivity of 0.714 and a specificity of 0.933. Overall, our study revealed the exosomal proteomic profiling of silicosis patients, silica-exposed workers, and controls, indicating that exosomes were significant in the pathogenesis of silicosis. It also revealed that the combined of the plasma levels of cytokines and the expression of exosomal DEPs could increase determination efficiency. This study provided directions for the development of silicosis biomarkers and a scientific basis for the pathogenesis research of silicosis in the future.

Echistatin/BYL-719 impedes epithelial-mesenchymal transition in pulmonary fibrosis induced by silica through modulation of the Integrin β1/ILK/PI3K signaling pathway

Silicosis is a chronic fibroproliferative lung disease caused by long-term inhalation of crystalline silica dust, characterized by the proliferation of fibroblasts and pulmonary interstitial fibrosis. Currently, there are no effective treatments available. Recent research suggests that the Integrin β1/ILK/PI3K signaling pathway may be associated with the pathogenesis of silicosis fibrosis. In this study, we investigated the effects of Echistatin (Integrin β1 inhibitor) and BYL-719 (PI3K inhibitor) on silicosis rats at 28 and 56 days after silica exposure. Histopathological analysis of rat lung tissue was performed using H&E staining and Masson staining. Immunohistochemistry, Western blotting, and qRT-PCR were employed to assess the expression of markers associated with epithelial-mesenchymal transition (EMT), fibrosis, and the Integrin β1/ILK/PI3K pathway in lung tissue. The results showed that Echistatin, BYL 719 or their combination up-regulated the expression of E-cadherin and down-regulated the expression of Vimentin and extracellular matrix (ECM) components, including type I and type III collagen. The increase of Snail, AKT and β-catenin in the downstream Integrin β1/ILK/PI3K pathway was inhibited. These results indicate that Echistatin and BYL 719 can inhibit EMT and pulmonary fibrosis by blocking different stages of Integrinβ1 /ILK/PI3K signaling pathway. This indicates that the Integrin β1/ILK/PI3K signaling pathway is associated with silica-induced EMT and may serve as a potential therapeutic target for silicosis.

Silicosis mortality in Spain (1999-2020): A temporal and geographical approach

Background

Silicosis is an occupational respiratory disease linked to silica dust inhalation. The main driver was traditional coal mining, but in recent decades, new sources of exposure have emerged. Our aim in this study was to assess the temporal and spatial distribution of mortality due to this disease over a 22-year period in Spain.

Methods

Silicosis records, as an Underlying Cause of Death, were extracted from the National Institute of Statistics from 1999 to 2020 using the International Classification of Diseases 10th revision (code J62.8). Age- and sex-adjusted mortality rates per 1,000,000 inhabitants were calculated for the territory and by province. A geographic analysis was performed, and clusters of deaths were identified at the municipal level, and then the outcomes were compared in two periods of 11 years.

Results

There were 2618 deaths due to silicosis in Spain. The mean age of death increased significantly by 0.66% annually from 1999 to 2013. The age-adjusted mortality rate decreased by 7.30% per year, falling from 3.00 to 0.65 per 1,000,000 inhabitants. The temporal pattern showed a significant decrease of mortality rate in 31% of the provinces (16 out of 52), while it increased in Pontevedra. Regarding the spatial analysis, 11 clusters were found in both periods, but some variations were observed in terms of their distribution in the Spanish territory, as well as in the affected municipalities.

Conclusions

The decrease in mortality due to Silicosis could be related to less exposure to silica dust over the years and an improvement in the survival of those affected. It is thus essential to analyze the role of preventive measures for this occupational disease.

Contributions of Synthetic Chemicals to Autoimmune Disease Development and Occurrence

PURPOSE OF REVIEW

Exposure to many synthetic chemicals has been linked to a variety of adverse human health effects, including autoimmune diseases. In this scoping review, we summarize recent evidence detailing the effects of synthetic environmental chemicals on autoimmune diseases and highlight current research gaps and recommendations for future studies.

RECENT FINDINGS

We identified 68 recent publications related to environmental chemical exposures and autoimmune diseases. Most studies evaluated exposure to persistent environmental chemicals and autoimmune conditions including rheumatoid arthritis (RA), systemic lupus (SLE), systemic sclerosis (SSc), and ulcerative colitis (UC) and Crohn's disease. Results of recent original research studies were mixed, and available data for some exposure-outcome associations were particularly limited. PFAS and autoimmune inflammatory bowel diseases (UC and CD) and pesticides and RA appeared to be the most frequently studied exposure-outcome associations among recent publications, despite a historical research focus on solvents. Recent studies have provided additional evidence for the associations of exposure to synthetic chemicals with certain autoimmune conditions. However, impacts on other autoimmune outcomes, particularly less prevalent conditions, remain unclear. Owing to the ubiquitous nature of many of these exposures and their potential impacts on autoimmune risk, additional studies are needed to better evaluate these relationships, particularly for understudied autoimmune conditions. Future research should include larger longitudinal studies and studies among more diverse populations to elucidate the temporal relationships between exposure-outcome pairs and to identify potential population subgroups that may be more adversely impacted by immune modulation caused by exposure to these chemicals.

From Engineered Stone Slab to Silicosis: A Synthesis of Exposure Science and Medical Evidence

Engineered stone (ES) is a popular building product, due to its architectural versatility and generally lower cost. However, the fabrication of organic resin-based ES kitchen benchtops from slabs has been associated with alarming rates of silicosis among workers. In 2024, fifteen years after the first reported ES-related cases in the world, Australia became the first country to ban the use and importation of ES. A range of interacting factors are relevant for ES-associated silicosis, including ES material composition, characteristics of dust exposure and lung cell-particle response. In turn, these are influenced by consumer demand, work practices, particle size and chemistry, dust control measures, industry regulation and worker-related characteristics. This literature review provides an evidence synthesis using a narrative approach, with the themes of product, exposure and host. Exposure pathways and pathogenesis are explored. Apart from crystalline silica content, consideration is given to non-siliceous ES components such as resins and metals that may modify chemical interactions and disease risk. Preventive effort can be aligned with each theme and associated evidence.

Incidence, mortality, and disability-adjusted life years due to silicosis worldwide, 1990-2019: evidence from the global burden of disease study 2019

Silicosis is an occupational lung disease because of exposure to silica dust in the workplace. Evidence on the spatiotemporal change of silicosis burden worldwide remains limited. This study utilized data extracted from the Global Burden of Disease Study 2019 to examine the numbers and age-standardized rates of incidence (ASIR), mortality (ASMR), and disability-adjusted life years (DALYs) caused by silicosis between 1990 and 2019. Average annual percentage changes (AAPCs) were calculated to evaluate the temporal trends of age-standardized indicators by sex, region, and socio-demographic index (SDI) since 1990. Results indicated an increase in new silicosis cases globally, rising by 64.61% from 84,426 in 1990 to 138,971 in 2019, with a sustained high number of DALYs attributed to this disease. Although the global age-standardized rates of incidence, mortality, and DALYs of silicosis have decreased since 1990, the number of new cases has increased in 168 countries and territories, and the ASIR of silicosis has also risen in 118 countries and territories, primarily in developing countries. Since 1990, the burden of silicosis among the elderly has significantly increased. Countries with higher SDI experienced a more rapid decline in the silicosis burden. Silicosis remains a public health problem that requires significant attention. Programs for prevention and elimination of this public health issue need to be established in more countries and territories. Protecting young workers from silica dust exposure is crucial to prevent the onset of silicosis in their later years and to reduce the disease burden among older workers.

Dose-response relationship between lung function and chest imaging response to silica exposures in artificial stone manufacturing workers

BACKGROUND

Occupational exposure to artificial stone, a popular material used for countertops, can cause accelerated silicosis, but the precise relationship between silica dose and disease development is unclear.

OBJECTIVES

This study evaluated the impact of silica exposure on lung function and chest imaging in artificial stone manufacturing workers.

METHODS

Questionnaire and spirometry assessments were administered to workers in two plants. A high-exposure subset underwent further evaluation, including chest CT and DLco. Weighting factors, assigned as proxies for silica exposure, were based on work tasks. Individual cumulative exposures were estimated using area concentration measurements and time spent in specific areas. Exposure-response associations were analyzed using linear and logistic regression models.

RESULTS

Among 65 participants, the mean cumulative silica exposure was 3.61 mg/m3-year (range 0.0001 to 44.4). Each 1 mg/m3-year increase was associated with a 0.46% reduction in FVC, a 0.45% reduction in FEV1, and increased lung function abnormality risk (aOR = 1.27, 95% CI = 1.03-1.56). Weighting factors correlated with cumulative exposures (Spearman correlation = 0.59, p < 0.0001), and weighted tenure was associated with lung function abnormalities (aOR = 1.04, 95% CI = 1.01-1.09). Of 37 high-exposure workers, 19 underwent chest CT, with 12 (63%) showing abnormal opacities. Combining respiratory symptoms, lung function, and chest X-ray achieved 91.7% sensitivity and 75% specificity for predicting chest CT abnormalities.

CONCLUSION

Lung function and chest CT abnormalities occur commonly in artificial stone workers. For high-exposure individuals, abnormalities on health screening could prompt further chest CT examination to facilitate early silicosis detection.

Epidemiology and Risk Factors for Rheumatoid Arthritis Development

Rheumatoid arthritis (RA) is a prevalent chronic inflammatory arthritis worldwide, significantly impacting patients and population health. The disease affects women primarily, with a female-to-male ratio of three to one. Its pathogenesis is multifactorial, including genetic and environmental risk factors. Epidemiological studies highlight the link between the environment and genetic susceptibility to RA. The so-called shared epitope is the most significant risk factor that seems to act synergetic with other environmental factors in the disease occurrence. In addition, recent findings suggest a potential role of new substantial environmental factors, such as the observed pollution of the planet's natural resources, on the susceptibility and progression of the disease. This review summarises the most decisive evidence on epidemiology and genetic, environmental, and lifestyle risk factors for RA. It shows that studying genetic and environmental factors in correlation could lead to prevention strategies that may impact the natural history of the disease.

Emerging trends in silicosis research: a scientometric review

Silicosis is a global disease whose prevention efforts cannot be ignored today. Although numerous silicosis-related data have been published recently, emphasizing the characteristics and nature of silicosis, a summary of the developmental laws of research is lacking, especially in the visual analysis of the literature. We aim to address this issue through a scientometric review. The Web of Science Core Collection and the All Databases were searched with "silicosis" as the topic, excluding unrelated publications, and obtained data from 9802 and 1613 publications, respectively. The data was then analyzed using the Web of Science's online scientometric analysis function and CiteSpace's visual analysis functionality, including publication volume analysis, co-occurrence analysis, co-citation analysis, cluster analysis, and explosive detection. The results identify the "respiratory system" as the most influential area over a century. Furthermore, the publication's number was correlated with the gross domestic product. We ranked countries and institutions based on the frequency of publications and discovered that Europe, the USA, and China are the leading regions for silicosis research, with the USA and Europe having a stronger influence. Many reports related to artificial stone and denim jean production have been studied through citation analysis, indicating new epidemic trends in silicosis. Besides, silicosis-related diseases and the pathogenesis of silicosis were the research hotspots of silicosis through co-occurrence keyword analysis and outbreak detection. Furthermore, related diseases include coal workers' pneumoconiosis and tuberculosis, while the mechanism of silicosis includes studies on inflammation and fibrosis, oxidative stress, alveolar macrophages, apoptosis, and pathways.

Beyond very early systemic sclerosis: deciphering pre‑scleroderma and its trajectories to open new avenues for preventive medicine

The identification of individuals with systemic sclerosis in an oligosymptomatic phase preceding the very early manifestations of the disease represents a challenge in the search for a new window of opportunity in systemic sclerosis. This phase could be identified in a clinical scenario as the pre-scleroderma phase, in which the disease would still be far from systemic sclerosis-related fibrotic or irreversible manifestations in skin or organs. In this Personal View, we discuss parameters and candidate definitions for a conceptual framework of pre-scleroderma, from the identification of populations at risk to autoantibodies and their potential functional activities. We discuss how this new paradigm of pre-scleroderma could represent a game-changing approach in the management of systemic sclerosis, allowing the treatment of patients at high risk of organ involvement or skin fibrosis before such events occur.

Incidence and prevalence of interstitial lung diseases worldwide: a systematic literature review

Interstitial lung disease (ILD) is a collective term representing a diverse group of pulmonary fibrotic and inflammatory conditions. Due to the diversity of ILD conditions, paucity of guidance and updates to diagnostic criteria over time, it has been challenging to precisely determine ILD incidence and prevalence. This systematic review provides a synthesis of published data at a global level and highlights gaps in the current knowledge base. Medline and Embase databases were searched systematically for studies reporting incidence and prevalence of various ILDs. Randomised controlled trials, case reports and conference abstracts were excluded. 80 studies were included, the most described subgroup was autoimmune-related ILD, and the most studied conditions were rheumatoid arthritis (RA)-associated ILD, systemic sclerosis associated (SSc) ILD and idiopathic pulmonary fibrosis (IPF). The prevalence of IPF was mostly established using healthcare datasets, whereas the prevalence of autoimmune ILD tended to be reported in smaller autoimmune cohorts. The prevalence of IPF ranged from 7 to 1650 per 100 000 persons. Prevalence of SSc ILD and RA ILD ranged from 26.1% to 88.1% and 0.6% to 63.7%, respectively. Significant heterogeneity was observed in the reported incidence of various ILD subtypes. This review demonstrates the challenges in establishing trends over time across regions and highlights a need to standardise ILD diagnostic criteria.PROSPERO registration number: CRD42020203035.

Co-Administration of Nanowired Monoclonal Antibodies to Inducible Nitric Oxide Synthase and Tumor Necrosis Factor Alpha Together with Antioxidant H-290/51 Reduces SiO2 Nanoparticles-Induced Exacerbation of Pathophysiology of Spinal Cord Trauma

Military personnel are often exposed to silica dust during combat operations across the globe. Exposure to silica dust in US military or service personnel could cause Desert Strom Pneumonitis also referred to as Al Eskan disease causing several organs damage and precipitate autoimmune dysfunction. However, the effects of microfine particles of sand inhalation-induced brain damage on the pathophysiology of traumatic brain or spinal cord injury are not explored. Previously intoxication of silica nanoparticles (50-60 nm size) is shown to exacerbates spinal cord injury induces blood-spinal cord barrier breakdown, edema formation and cellular changes. However, the mechanism of silica nanoparticles-induced cord pathology is still not well known. Spinal cord injury is well known to alter serotonin (5-hydroxytryptamine) metabolism and induce oxidative stress including upregulation of nitric oxide synthase and tumor necrosis factor alpha. This suggests that these agents are involved in the pathophysiology of spinal cord injury. In this review, we examined the effects of combined nanowired delivery of monoclonal antibodies to neuronal nitric oxide synthase (nNOS) together with tumor necrosis factor alpha (TNF-α) antibodies and a potent antioxidant H-290/51 to induce neuroprotection in spinal cord injury associated with silica nanoparticles intoxication. Our results for the first time show that co-administration of nanowired delivery of antibodies to nNOS and TNF-α with H-290/51 significantly attenuated silica nanoparticles-induced exacerbation of spinal cord pathology, not reported earlier.

Probabilistic health risk assessment of occupational exposure to crystalline silica in an iron foundry in Urmia, Iran

This study aimed to quantify the exposure of foundry workers to crystalline silica and associated cancer and non-cancer health risks using a probabilistic approach. Breathing zone air samples were collected according to the NIOSH 7602 method and analyzed using Fourier transform infrared spectroscopy. The health risks posed by crystalline silica were then assessed using the EPA-developed inhalation risk assessment model and Monte Carlo simulation. The sensitivity analysis was also conducted to determine the contribution of input parameters to the health risks. The mean concentration of crystalline silica in six foundry stations ranged from 0.029 to 0.064 mg m-3, exceeding the occupational exposure limits. The average values of cancer risks were greater than the USEPA level, i.e., 1E - 6 in all workstations of the foundry. Workers in sand preparation and molding stations suffered the greatest cancer risks, with the mean value of 2.35E - 5 and 2.10E - 5, respectively. Non-cancer hazard quotient exceeded 1 in all foundry stations ranging from 1.56 (in melting and pouring) to 3.37 (in sand preparation). The 95% upper-bound values of the health risks decreased by 77.52% and 56.77%, assuming the use of engineering controls and wearing respirators by workers, respectively. Sensitivity analyses indicate that concentration was the most sensitive factor contributing to the carcinogenic (46.13%) and non-carcinogenic (67.08%) risks. These findings can aid managers in gaining a better understanding of the silica risks faced by foundry workers and the role of engineering controls and respirators in protecting workers' health.

Sarcoid-like Lung Disease as a Reaction to Silica from Exposure to Bentonite Cat Litter Complicated by End-Stage Renal Failure-A Case Report

A 44-year-old woman was admitted to hospital with end-stage renal failure, productive cough, and decreased exercise tolerance. She had owned nine cats, which resulted in long-term exposure (18 years) to silica-containing bentonite cat litter. High-resolution computed tomography of the chest showed micronodular lesions in the lungs, and mild mediastinal lymphadenopathy. A lung biopsy revealed multinucleated giant cells, some of which had birefringent material and Schaumann bodies. X-ray photoelectron spectroscopy revealed the presence of silicon in the lung biopsy specimen, as well as in the patient's cat litter. The pulmonary condition was suggestive of sarcoid-like lung disease, rather than silicosis, sarcoidosis, or hypersensitivity pneumonitis, according to the clinicopathological findings. Renal failure appeared to be a result of chronic hypercalcemia due to extrarenal calcitriol overproduction in activated alveolar macrophages. Ultimately, the patient was diagnosed with sarcoid-like lung disease complicated by end-stage renal failure from exposure to bentonite cat litter. Therapy with steroids, in addition to elimination of the bentonite cat litter exposure, resulted in a significant improvement in the health condition. At a follow-up visit after 4 months, an almost complete resolution of the lung lesions and a significant improvement in renal function were observed.

Genetic polymorphisms and their effects on the severity of silicosis in workers exposed to silica in Brazil

Objective: Silicosis is a pneumoconiosis characterized by fibrosis of the lung parenchyma caused by inhalation of silica particles. Genetic factors might play a role in the severity silicosis. We sought to evaluate the influence of polymorphisms in the ACE, FAS, FASLG, NOS2, IL1RN, FAM13A, TGFB1, and TNF genes on the severity of silicosis. Methods: Nine polymorphisms were genotyped by PCR in a sample of 143 patients with silicosis in the state of Rio de Janeiro, Brazil. Results: Fifty-seven patients (40%) were classified as having simple silicosis and 86 (60%) were classified as having complicated silicosis. The TT genotype of rs1800469 in the TGFB1 gene showed a protective effect for complicated silicosis (OR = 0.35; 95% CI, 0.14-0.92; p = 0.028) when compared with the other two genotypes (CC+CT). The polymorphic T allele of rs763110 in the FASLG gene (OR = 0.56; 95% CI, 0.31-0.99; p = 0.047), as well as a dominant model for the T allele (TT+CT: OR = 0.37; 95% CI, 0.15-0.96; p = 0.037), also showed a protective effect. When patients with simple silicosis despite having been exposed to silica for a longer time (> 44,229 hours) were compared with patients with complicated silicosis despite having been exposed to silica for a shorter time, the T allele of rs763110 in the FASLG gene (OR = 0.20; 95% CI, 0.08-0.48; p < 0.0001), as well as dominant and recessive models (OR = 0.06; 95% CI, 0.00-0.49; p = 0.01 and OR = 0.22; 95% CI, 0.06-0.77; p = 0.014, respectively), showed a protective effect against the severity of silicosis. Conclusions: It appears that rs1800469 polymorphisms in the TGFB1 gene and rs763110 polymorphisms in the FASLG gene are involved in the severity of silicosis. Given the lack of studies relating genetic polymorphisms to the severity of silicosis, these results should be replicated in other populations.

Workers' Occupational Dust Exposure and Pulmonary Function Assessment: Cross-Sectional Study in China

OBJECTIVE

This study aims to determine the occupational health status of workers exposed to dust and the risk factors of lung function decline, to provide a basis for formulating corresponding occupational disease-prevention strategies.

METHODS

Data on 2045 workers exposed to dust, including their age, gender, exposure time, chest X-ray test results, and pulmonary function test results, were obtained from a key occupational disease monitoring project in Chongqing, China, in 2021. Chi-square tests and multifactorial logistic regression, and other methods, were used for statistical analysis.

RESULTS

The prevalence of pneumoconiosis-like changes was 0.83% (17/2045), and the prevalence of abnormal forced expiratory volume in one second (FEV₁), forced vital capacity (FVC), and FEV₁/FVC was 4.25% (87/2045), 12.81% (262/2045), and 1.47% (30/2045), respectively. With increasing worker's age, the prevalence of abnormal pneumoconiosis-like changes (p = 0.0065), FEV₁ (p = 0.0002), FVC (p < 0.0001), and FEV₁/FVC (p = 0.0055) all increased. Factors such as age, exposure duration, enterprise size, and dust exposure concentration were associated with abnormal lung function.

CONCLUSIONS

Workers exposed to occupational dust have a high rate of abnormal lung function. The government, enterprises, and individuals should pay attention to occupational dust exposure, and various effective measures should be actively taken to protect the life and health of workers.