Joint effects of smoking and silicosis on diseases to the lungs

Association of complete blood count parameters with the risk of incident pulmonary heart disease in pneumoconiosis: a retrospective cohort study

BACKGROUND

Pneumoconiosis mostly combines pulmonary and cardiovascular diseases, among which pulmonary heart disease (PHD) is of major concern due to its significant impact on the survival of pneumoconiosis patients. White cell count (WCC), red cell distribution width (RDW) and platelet parameters are thought to affect inflammatory responses and may be predictors of various cardiovascular diseases. However, very few studies have focused on PHD.

OBJECTIVES

To examine the relationship between baseline complete blood count parameters (WCC, RDW, platelet parameters) and the risk of incident PHD in pneumoconiosis patients.

DESIGN

A retrospective cohort study.

SETTING

This was a single-centre, retrospective cohort study that used data from an Occupational Disease Hospital, Chengdu, Sichuan.

PARTICIPANTS

A total of 946 pneumoconiosis patients from January 2012 to November 2021 were included in the study. Female patients and patients who had PHD, coronary heart disease, hypertensive heart disease, cardiomyopathy, heart failure, oncological disease, multiple organ dysfunction, AIDS at baseline and follow-up time of less than 6 months were also excluded.

OUTCOME MEASURES

We identified PHD according to the patient's discharge diagnosis. We constructed Cox proportional hazard regression models to assess the HR of incident PHD in pneumoconiosis, as well as 95% CIs.

RESULTS

In the multiple Cox proportional hazard regression analysis, platelet count (PLT) and plateletcrit (PCT) above the median at baseline were associated with an increased risk of PHD in pneumoconiosis with adjusted HR of 1.52 (95% CI 1.09 to 2.12) and 1.42 (95% CI 1.02 to 1.99), respectively.

CONCLUSION

Higher baseline PLT and PCT are associated with a higher risk of PHD in pneumoconiosis.

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.

Prevalence of pulmonary hypertension in chronic simple silicosis patients and its correlation with smoking history, occupation type, age and duration of silica exposure

Silicosis is a preventable occupational health hazard with potential for permanent physical disability and increased socio-economic burden. Pulmonary hypertension (PH) secondary to chronic respiratory diseases signifies poorer prognosis and transthoracic echocardiography (TTE) has proven its usefulness as a screening tool for PH diagnosis. The objectives were to determine PH prevalence in chronic simple silicosis patients through TTE screening and correlate PH prevalence with smoking status, occupation type, age and duration of silica exposure (DSE). We enrolled 104 patients in the study based on occupational exposure to silica dust and radiologic confirmation of chronic simple silicosis. The study sample was divided into significant smokers (SS group) and insignificant smokers (InS group) on the basis of ≥10 pack years smoking history, and into drillers and dressers based on occupation type. TTE examination was performed to measure resting mean pulmonary artery pressure (mPAP) and the patients were classified into: no PH (mPAP≤20 mm Hg), borderline PH (mPAP>20 and <25 mmHg), and PH (mPAP≥25). PH prevalence was 25% in study subjects (26/104); 29.6% (16/54) among SS group versus 20% (10/50) among InS group (.52) ; and 34.2% (14/41) among drillers versus 19.1% (12/63) among dressers (p=.024). Mean age and mean duration of silica exposure among SS and InS groups were comparatively similar, while they had lower values among dressers against dressers with no statistical significance. Logistic regression analysis established a significant association of PH prevalence with higher age in the study sample, SS group and drillers group, while a significant association of PH prevalence with longer DSE was only seen in the study sample. PH prevalence was significantly associated (p=.007) with SS-driller group on comparing TTE findings with combined smoking and occupation type based groups. This study has shown PH prevalence in chronic simple silicosis patients at alarming levels, having associations with driller occupation, older age and longer DSE with varying results among groups and complex interplay with smoking exposure, suggesting the need for large sample-based molecular and genetic studies. Including TTE in the initial work-up of silicosis patients will promote timely intervention and reduce morbidity and mortality with a high benefit-cost ratio.

Potential Effect of Combined Exposure of Crystalline Silica Dust and Cigarette Smoking on the Incidence of Silicosis among Chinese Male Stone Processing Workers: A Cross-Sectional Study

Background: Silicosis is a progressive and irreversible disease primarily caused by exposure to crystalline silica dust and, to a lesser extent, cigarette smoking. However, further research is needed to validate the potential combined effect of these risk factors on the increased incidence of the disease. Methods: A total of 1688 male workers employed at a Chinese stone processing plant between 1 January 1999 and 31 December 2019, were included in the study. Cumulative exposure to industrial crystalline silica dust and packyears of smoking were collected through health surveillance, and odds ratios (ORs) with 95% confidence intervals (CIs) for silicotic changes due to industrial silica exposure and cigarette smoking were estimated using logistic regression models. Results: Among all participants, a significant exposure-response relationship was observed between long-term exposure to industrial silica dust and radiographic findings resembling silicosis (OR 1.74, 95% CI 1.25 to 2.41). However, among middle-aged workers, a weak and statistically insignificant relationship was found between prolonged cigarette smoking and X-ray evidence of lung silicosis (OR 1.59, 95% CI 1.00 to 2.53). Furthermore, significant combined effects, exceeding the additive models, were identified in each age group and employment sector (relative risk due to interaction 0.51, 95% CI 0.08 to 3.42). Conclusions: It is critically important to implement effective dust removal measures and tobacco control strategies in order to enhance respiratory health among employees across all age groups in the stone processing industry.

Silicosis and tuberculosis: A systematic review and meta-analysis

INTRODUCTION

Silicosis mostly happens in workers with high silica exposure and may accompany the development of various diseases like tuberculosis, cancer, or autoimmune diseases. The term silico-tuberculosis describes a condition in which an individual is affected by both silicosis and tuberculosis at the same time. This systematic review and meta-analysis study was conducted to evaluate the risk of tuberculosis in silicosis patients and individuals exposed to silica dust.

METHODS

We performed a systematic search for relevant studies up to 6 September 2022 using PubMed/ Medline, and Embase with the following keywords in titles or abstracts: "silicosis" OR "silicoses" OR "pneumoconiosis" OR "pneumoconioses" AND "tuberculosis". Cohort and case-control studies containing relevant and original information about tuberculosis infection in silicosis patients were included for further analysis. Pooled estimates and 95% confidence intervals (CI) for the relative risk of tuberculosis in individuals with silicosis compared to those without; these were evaluated using the random effects model due to the estimated heterogeneity of the true effect sizes.

RESULTS

Out of 5352 potentially relevant articles, 7 studies were eligible for systematic review, of which 4 cohort studies were included for meta-analysis. The total population of all studies was 5884, and 90.63% were male. The mean age of participants was 47.7 years. Our meta-analysis revealed a pooled risk ratio of 1.35 (95%CI 1.18-1.53, I ²: 94.30%) which means an increased risk of silicosis patients and silica-exposed individuals to tuberculosis infection.

CONCLUSION

Silicosis and silica dust exposure increase the risk of tuberculosis. Therefore, we suggest that individuals with long-time silica exposure, like mine workers, be routinely considered for both silicosis and tuberculosis screening programs.

The influence of fatigue on work capacity and quality of life among miners with silicosis

Introduction

Factors associated with the mining environment can contribute to work accidents and reduced caution at work, which may affect the quality of life and work capacity of miners.

Objectives

To evaluate if fatigue influences quality of life and work capacity in miners with silicosis.

Methods

This was a cross-sectional study conducted in the Northern Region of the state of Rio Grande do Sul, Brazil. Sociodemographic data and data on fatigue, work capacity, and quality of life were collected during the second half of 2017 and first half of 2018.

Results

All participants were men. Mean participant age was 52.6 (± 7.2) years, and most (70.4%) of them did not finish elementary school. The strongest correlations were found between the physical, overall, and total fatigue domains and the World Health Organization Quality of Life - BREF and between the total and mental fatigue domains and the Work Ability Index. Strong correlations were also found between overall and total fatigue and the total St. George's Respiratory Questionnaire score.

Conclusions

Silicosis and physical workload have a negative impact on respiratory quality of life and perception of fatigue among miners.

Nicotine exposure exacerbates silica-induced pulmonary fibrosis via STAT3-BDNF-TrkB-mediated epithelial-mesenchymal transition in alveolar type II cells

The addictive substance nicotine, found in cigarettes and some e-cigarettes, plays a vital role in pro-inflammatory and fibrotic processes. However, the part played by nicotine in the progression of silica-induced pulmonary fibrosis is poorly understood. We used mice exposed to both silica and nicotine to investigate whether nicotine synergizes with silica particles to worsen lung fibrosis. The results revealed that nicotine accelerated the development of pulmonary fibrosis in silica-injured mice by activating STAT3-BDNF-TrkB signalling. Mice with a history of exposure to nicotine showed an increase in Fgf7 expression and alveolar type II cell proliferation if they were also exposed to silica. However, newborn AT2 cells could not regenerate the alveolar structure and release pro-fibrotic factor IL-33. Moreover, activated TrkB induced the expression of p-AKT, which promotes the expression of epithelial-mesenchymal transcription factor Twist, but no Snail. In vitro assessment confirmed activation of the STAT3-BDNF-TrkB pathway in AT2 cells, exposed to nicotine plus silica. In addition, TrkB inhibitor K252a downregulated p-TrkB and the downstream p-AKT and restricted the epithelial-mesenchymal transition caused by nicotine plus silica. In conclusion, nicotine activates the STAT3-BDNF-TrkB pathway, which promotes epithelial-mesenchymal transition and exacerbates pulmonary fibrosis in mice with combined exposure to silica particles and nicotine.

Epidemiological characteristics and survival analysis on patients with occupational pneumoconiosis in Zhejiang Province from 1987 to 2019

Objective

To evaluate risk factors affecting survival in patients diagnosed with pneumoconiosis and propose strategies to improve the quality of life in these patients.

Methods

The basic patient information was obtained from the pneumoconiosis report card. Disease types, regions, and industry distribution of pneumoconiosis were analyzed. The Kaplan-Meier survival curves and the Cox proportional risk regression model was used for survival analysis.

Results

A total of 13,812 patients were diagnosed with pneumoconiosis in Zhejiang province from 1987 to 2019. The overall survival rate at the end of life table analysis was 83%. Kaplan-Meier analyses showed that there were significant differences between survival curves depending on the stage of first diagnosis, age at first diagnosis, type of pneumoconiosis, industry, and duration of dust exposure (P < 0.05). The results of Cox proportional hazards regression analysis showed that pneumoconiosis stage of first diagnosis, age at first diagnosis, industry, and duration of dust exposure were risk factors affecting patient survival (P < 0.05).

Conclusions

The patients with high stage of pneumoconiosis at first diagnosis, older age, and long duration of dust exposure should be followed up and monitored as key population, and the industries with high incidence of pneumoconiosis such as mining and construction should be supervised as key industries.

Towards Treatable Traits for Pulmonary Fibrosis

Interstitial lung diseases (ILD) are a heterogeneous group of disorders, of which many have the potential to lead to progressive pulmonary fibrosis. A distinction is usually made between primarily inflammatory ILD and primarily fibrotic ILD. As recent studies show that anti-fibrotic drugs can be beneficial in patients with primarily inflammatory ILD that is characterized by progressive pulmonary fibrosis, treatment decisions have become more complicated. In this perspective, we propose that the ‘treatable trait’ concept, which is based on the recognition of relevant exposures, various treatable phenotypes (disease manifestations) or endotypes (shared molecular mechanisms) within a group of diseases, can be applied to progressive pulmonary fibrosis. These targets for medical intervention can be identified through validated biomarkers and are not necessarily related to specific diagnostic labels. Proposed treatable traits are: cigarette smoking, occupational, allergen or drug exposures, excessive (profibrotic) auto- or alloimmunity, progressive pulmonary fibrosis, pulmonary hypertension, obstructive sleep apnea, tuberculosis, exercise intolerance, exertional hypoxia, and anxiety and depression. There are also several potential traits that have not been associated with relevant outcomes or for which no effective treatment is available at present: air pollution, mechanical stress, viral infections, bacterial burden in the lungs, surfactant-related pulmonary fibrosis, telomere-related pulmonary fibrosis, the rs35705950 MUC5B promoter polymorphism, acute exacerbations, gastro-esophageal reflux, dyspnea, and nocturnal hypoxia. The ‘treatable traits’ concept can be applied in new clinical trials for patients with progressive pulmonary fibrosis and could be used for developing new treatment strategies.

Long-term follow-up of young denim sandblasters in Turkey

BACKGROUND

Denim sandblasting-induced silicosis is a recently identified occupational disease.

AIMS

In this study, we aimed to evaluate pulmonary and radiological changes in the long-term follow-up of former denim sandblasters.

METHODS

Ninety former denim sandblasters were followed from 2007 to 2018. Chest X-rays were evaluated according to the International Labour Organization (ILO) classification. Baseline and final data were compared. Silicosis prevalence, radiological progression and pulmonary dysfunction were evaluated.

RESULTS

All of the sandblasters were men. Their mean age was 34 ± 5 years, mean follow-up time was 9 ± 2 years (mean time since initial exposure: 17 ± 2 years) and mean duration of exposure was 34 ± 25 months. Rates of radiological progression and decline in pulmonary during follow-up were 63% and 39%, respectively. During follow-up, all patients were diagnosed with silicosis. All workers who were ILO category 0 at baseline (n = 26, 29%) progressed to higher categories. The number of patients in Category 2 doubled and the number of patients in Category 3 increased by 2.5-fold. Eleven patients developed new large opacities and the number of patients with category C opacity increased from 4 to 13. Exposure time was an independent determinant of radiological progression (OR: 1.0, P = 0.036) and decline in pulmonary function (OR: 1.3, P = 0.019).

CONCLUSION

The prevalence of silicosis in denim sandblasters increases steadily even after exposure is discontinued. Radiological progression was observed in a higher proportion of workers than a decline in lung function. Duration of exposure was the major determinant of disease progression in our study.

Respiratory health and silicosis in artisanal mine workers in southern Brazil

BACKGROUND

Artisanal and small-scale mining (ASM) are an important source of employment in southern Brazil. Mining workers are frequently exposed to unhealthy work conditions which increase the risk of occupational diseases. In this study, we assessed the association of sociodemographic factors and the occupational history of artisanal mining workers with the risk of adverse respiratory outcomes.

METHODS

The study was conducted with 258 artisanal mining workers in southern Brazil, who were exposed to dust (mainly crystalline silica) in their work. Information on sociodemographic variables and occupational histories was collected between 2017 and 2018. To estimate the worker's exposure to inhalable dust we use the Advanced REACH (Registration, Evaluation, and Authorization of Chemicals) Tool (ART).

RESULTS

Study participants were all men, with an average age of 40 years. Median crude dust exposure estimated by ART was 13.2 mg/m³ and median crude crystalline silica exposure was 1.6 mg/m³ . The prevalence ratio (PR) for self-reported silicosis was 3.08 (95% confidence interval, 1.39-7.17) in workers with 20 years or more of mining work. Factors associated with silicosis were age, pack-years of tobacco use, and body mass index. Smokers were over twice as likely to report respiratory symptoms.

CONCLUSIONS

Our findings indicate that a high prevalence of silicosis and other associated diseases in mining workers is associated with both unhealthy work environment conditions and the health profile of workers. This study is an important step for understanding health outcomes from work in ASM.

Predictors of health-related quality of life among semi-precious stone mineworkers exposed to silica dust

OBJECTIVE

The study aimed to comparatively evaluate HRQOL in miners of semi-precious stones with and without silicosis, and determine the associated factors, as well as the performance of two different questionnaires in measuring HRQOL.

METHODS

In a cross-sectional study of 348 male miners (129 with silicosis) who underwent an interview and spirometry, HRQOL was assessed using the World Health Organization Quality of Life (WHOQOL-BREF) questionnaire and the Saint George's Respiratory Questionnaire (SGRQ).

RESULTS

Miners with silicosis were older, had less schooling, worked more hours daily, and had longer exposure to silica. They also had worse scores of QoL in both questionnaires. Respiratory symptoms and %FEV₁ were contributing factors for the models of total health and all the domains of the SGRQ, and 40% of the variability of the general health domain of WHOQOL-BREF was due to dyspnea, wheezing, %FEV₁, and pack-years of cigarette smoking. Respiratory symptoms, lung function, pack-years of cigarette smoking, years of education, and average monthly income were contributing factors for the models of the different domains of the WHOQOL-BREF.

CONCLUSIONS

Our study revealed impaired HRQOL in semi-precious stone miners evaluated using both questionnaire tools of SGRQ and WHOQOL-BREF, of which SGRQ had superior performance. Respiratory symptoms, functional impairment, and pack-years of cigarette smoking were the most important determinants of the workers' general HRQOL.

Tobacco Smoke Exposure Exacerbated Crystalline Silica-Induced Lung Toxicity in Rats

Smoking may modify the lung response to silica exposure including cancer and silicosis. Nevertheless, the precise role of exposure to tobacco smoke (TS) on the lung response to crystalline silica (CS) exposure and the underlying mechanisms need further clarification. The objectives of the present study were to determine the role of TS on lung response to CS exposure and the underlying mechanism(s). Male Fischer 344 rats were exposed by inhalation to air, CS (15 mg/m3, 6 h/day, 5 days), TS (80 mg/m3, 3 h/day, twice weekly, 6 months), or CS (15 mg/m3, 6 h/day, 5 days) followed by TS (80 mg/m3, 3 h/day, twice weekly, 6 months). The rats were euthanized 6 months and 3 weeks following initiation of the first exposure and the lung response was assessed. Silica exposure resulted in significant lung toxicity as evidenced by lung histological changes, enhanced neutrophil infiltration, increased lactate dehydrogenase levels, enhanced oxidant production, and increased cytokine levels. The TS exposure alone had only a minimal effect on these toxicity parameters. However, the combined exposure to TS and CS exacerbated the lung response, compared with TS or CS exposure alone. Global gene expression changes in the lungs correlated with the lung toxicity severity. Bioinformatic analysis of the gene expression data demonstrated significant enrichment in functions, pathways, and networks relevant to the response to CS exposure which correlated with the lung toxicity detected. Collectively our data demonstrated an exacerbation of CS-induced lung toxicity by TS exposure and the molecular mechanisms underlying the exacerbated toxicity.

Asbestosis and silicosis hospitalizations in Italy (2001-2015): results from the National Hospital Discharge Registry

BACKGROUND

This work is aimed at evaluating the quality of Italian hospitalizations data about asbestosis and silicosis, assessing the impact of these diseases on the national health system and providing advice related to public health.

METHODS

Italian hospital discharge data (2001-15) with diagnosis of asbestosis or silicosis were analysed by the multiple correspondence analysis and diseases epidemics were evaluated through hospitalization rates.

RESULTS

Hospitalizations were concentrated in the northwestern area, referred mainly to males and oldest people, the most treated tumors were lung cancer and mesothelioma (for asbestosis) and cares were aimed at reducing symptoms and increasing blood oxygenation. Overall adjusted Italian hospitalization rates of asbestosis and silicosis were, respectively, 25.2 and 74.9 per 1 000 000 residents. With respect to asbestosis, hospitalizations treating silicosis reported doubled mortality (10.5 vs. 5.7%), longer stays (10.4 vs. 8.6 mean days) and older patients (77 vs. 72 years on average). Diseases rates reduced over time (with a steeper slope for silicosis) and in both fibroses increased hospital mortality (92.1% in asbestoses, 59.5% in silicoses) and percentage of urgent hospitalizations (116.0% in asbestoses, 56.6% in silicoses).

CONCLUSION

Hospitalizations data regarding asbestosis and silicosis are consistent. Silicosis had a higher impact than asbestosis on the Italian health system. Although data show decreasing incidence of both fibroses, multiple correspondence analysis highlights that levels of illness severity were higher in silicosis and increased over time in both diseases. Further studies investigating the effectiveness of the current health surveillance programs concerning these diseases are suggested.

Association of occupational dust exposure with combined chronic obstructive pulmonary disease and pneumoconiosis: a cross-sectional study in China

OBJECTIVES

Occupational dust exposure may induce various lung diseases, including pneumoconiosis and chronic obstructive pulmonary disease (COPD). The features of combined COPD and pneumoconiosis have not been well described, and this may hamper the management. This study aimed to describe the prevalence and characteristics as well as the risk factors of the combined diseases.

DESIGN

A cross-sectional study.

SETTING AND PARTICIPANTS

758 patients with pneumoconiosis were recruited at a single-medical centre. Of these, 675 patients with pneumoconiosis, including asbestosis, silicosis, coal workers' pneumoconiosis and other pneumoconiosis, was eligible for analysis.

PRIMARY OUTCOME MEASURES

COPD was diagnosed based on clinical features and/or history of exposure to risk factors and post bronchodilator forced expiratory volume in 1 s (FEV₁)/forced vital capacity (FVC) ratio <0.7. Clinical data were collected from predesigned medical reports. The patients underwent both chest radiograph and high-resolution CT scans. Risk factors for combined COPD and pneumoconiosis were analysed using regression analysis.

RESULTS

COPD prevalence overall was 32.7% (221/675) and was the highest in silicosis (84/221) and coal workers' pneumoconiosis (100/221). COPD prevalence increased with smoking pack-years, dust exposure duration and pneumoconiosis stage. Patients with combined diseases had lower body mass index, higher smoking index and worse pulmonary function. Risk factors for combined diseases included heavy smoking, silica or coal exposure and advanced pneumoconiosis. The interaction between dust exposure and smoking in COPD was also identified. The risk of combined COPD significantly increased with heavy smoking and silica or coal exposure (OR 5.49, 95% CI 3.04 to 9.93, p<0.001).

CONCLUSIONS

COPD is highly prevalent in patients with pneumoconiosis, especially patients with silicosis and coal workers' pneumoconiosis. Occupational dust exposure as well as heavy smoking is associated with an increased risk of combined COPD and pneumoconiosis, which demands an effective preventive intervention.

Influences of Nanoparticles Characteristics on the Cellular Responses: The Example of Iron Oxide and Macrophages

Iron oxide nanoparticles/microparticles are widely present in a variety of environments, e.g., as a byproduct of steel and iron degradation, as, for example, in railway brakes (e.g., metro station) or in welding fumes. As all particulate material, these metallic nanoparticles are taken up by macrophages, a cell type playing a key role in the innate immune response, including pathogen removal phagocytosis, secretion of free radical species such as nitric oxide or by controlling inflammation via cytokine release. In this paper, we evaluated how macrophages functions were altered by two iron based particles of different size (100 nm and 20 nm). We showed that at high, but subtoxic concentrations (1 mg/mL, large nanoparticles induced stronger perturbations in macrophages functions such as phagocytic capacity (tested with fluorescent latex microspheres) and the ability to respond to bacterial endotoxin lipopolysaccharide stimulus (LPS) in secreting nitric oxide and pro-cytokines (e.g., Interleukin-6 (IL-6) and Tumor Necrosis Factor (TNF)). These stronger effects may correlate with an observed stronger uptake of iron for the larger nanoparticles.

Update on the approach to smoking in patients with respiratory diseases

Smoking is the leading cause of respiratory disease (RD). The harmful effects of smoking on the respiratory system begin in utero and influence immune responses throughout childhood and adult life. In comparison with "healthy" smokers, smokers with RD have peculiarities that can impede smoking cessation, such as a higher level of nicotine dependence; nicotine withdrawal; higher levels of exhaled carbon monoxide; low motivation and low self-efficacy; greater concern about weight gain; and a high prevalence of anxiety and depression. In addition, they require more intensive, prolonged treatment. It is always necessary to educate such individuals about the fact that quitting smoking is the only measure that will reduce the progression of RD and improve their quality of life, regardless of the duration and severity of the disease. Physicians should always offer smoking cessation treatment. Outpatient or inpatient smoking cessation treatment should be multidisciplinary, based on behavioral interventions and pharmacotherapy. It will thus be more effective and cost-effective, doubling the chances of success.

Prevalence of latent tuberculosis infection among coal workers' pneumoconiosis patients in China: a cross-sectional study

BACKGROUND

Little is known about the prevalence of latent tuberculosis infection (LTBI) among coal workers' pneumoconiosis (CWP) patients. To estimate the prevalence of LTBI and identify its associated risk factors among CWP patients.

METHODS

A cross-sectional study was conducted to assess the prevalence of LTBI. Participants were screened for active TB or a history of TB by X-ray and those that underwent QuantiFERON-TB Gold In-Tube (QFT) test. A standardized questionnaire was completed and risk factors were assessed for acquiring TB. Log-binomial regression was used to estimate the LTBI prevalence ratio (PR) in relation to risk factors.

RESULTS

Of 244 individuals with CWP (median age 67 years; all male), 162 (66.4%) were QFT positive. In Multivariate analysis, poor workplace ventilation (adjusted prevalence ratio [APR] = 1.26) and intake of fruits regularly (≥4 days of every week) (APR = 0.81) (all p < 0.05) were associated with a decreased risk of QFT.

CONCLUSIONS

This study showed a high prevalence of LTBI among individuals with CWP in China. Poor workplace ventilation may be an important contributing factor for LTBI. Regular monitoring and dust control measures need to be improved in workplaces to ensure the safety of workers. Moreover, intake of fruits regularly may be a protective factor for LTBI. However, the effect of fruits should be further studied.

Inflammasome-Independent Leukotriene B4 Production Drives Crystalline Silica-Induced Sterile Inflammation

Silicosis is a lung inflammatory disease caused by chronic exposure to crystalline silica (CS). Leukotriene B₄ (LTB₄) plays an important role in neutrophilic inflammation, which drives silicosis and promotes lung cancer. In this study, we examined the mechanisms involved in CS-induced inflammatory pathways. Phagocytosis of CS particles is essential for the production of LTB₄ and IL-1β in mouse macrophages, mast cells, and neutrophils. Phagosomes enclosing CS particles trigger the assembly of lipidosome in the cytoplasm, which is likely the primary source of CS-induced LTB₄ production. Activation of the JNK pathway is essential for both CS-induced LTB₄ and IL-1β production. Studies with bafilomycin-A1- and NLRP3-deficient mice revealed that LTB₄ synthesis in the lipidosome is independent of inflammasome activation. Small interfering RNA knockdown and confocal microscopy studies showed that GTPases Rab5c, Rab40c along with JNK1 are essential for lipidosome formation and LTB₄ production. BI-78D3, a JNK inhibitor, abrogated CS-induced neutrophilic inflammation in vivo in an air pouch model. These results highlight an inflammasome-independent and JNK activation-dependent lipidosome pathway as a regulator of LTB₄ synthesis and CS-induced sterile inflammation.

Total and Cause-Specific Mortality Risk Associated With Low-Level Exposure to Crystalline Silica: A 44-Year Cohort Study From China

The association between low-level crystalline silica (silica) exposure and mortality risk is not well understood. We investigated a cohort of 44,807 Chinese workers who had worked in metal mines or pottery factories for at least 1 year from January 1, 1960, to December 31, 1974, and were followed through 2003. Low-level silica exposure was defined as having a lifetime highest annual mean silica exposure at or under a permissible exposure limit (PEL). We considered 3 widely used PELs, including 0.05 mg/m3, 0.10 mg/m3, and 0.35 mg/m3. Cumulative silica exposure was estimated by linking a job exposure matrix with each participant's work history. For the 0.10-mg/m3 exposure level, Cox proportional hazards models showed significantly increased risk of mortality from all diseases (for each 1-ln mg/m3-years increase in logged cumulative silica exposure, hazard ratio (HR) = 1.05, 95% confidence interval (CI): 1.03, 1.07), malignant neoplasms (HR = 1.06, 95% CI: 1.03, 1.09), lung cancer (HR = 1.08, 95% CI: 1.02, 1.14), ischemic heart disease (HR = 1.09, 95% CI: 1.02, 1.16), pulmonary heart disease (HR = 1.08, 95% CI: 1.00, 1.16), and respiratory disease (HR = 1.20, 95% CI: 1.14, 1.26). The 0.05-mg/m3 and 0.35-mg/m3 exposure levels yielded similar associations. Long-term exposure to low levels (PELs ≤0.05 mg/m3, ≤0.10 mg/m3, or ≤0.35 mg/m3) of silica is associated with increased total and certain cause-specific mortality risk. Control of ambient silica levels and use of personal protective equipment should be emphasized in practice.

High Cigarette and Poly-Tobacco Use Among Workers in a Dusty Industry: New Jersey Quarry Workers

OBJECTIVE

Tobacco use is high among US extraction and construction workers, who can also incur occupational dust exposure. Information on different types of tobacco use among quarry/mine workers is sparse.

METHODS

During mandated training sessions, New Jersey quarry workers were surveyed about their tobacco use. Prevalence was calculated for single and multiple tobacco use by demographic and workplace characteristics; logistic regression was used to assess associations with smoking.

RESULTS

Two hundred forty (97.1%) workers completed surveys. Among respondents, 41.7% [95% confidence interval (95% CI) 35.4 to 48.3] currently used any tobacco product of whom 28.1% smoked cigarettes. In multivariate analysis, positive associations with smoking included working as a contractor versus mine employee (odds ratio 2.32, 95% CI 1.01 to 5.36) and a usual job title of maintenance (odds ratio 2.02, 95% CI 0.87 to 4.94).

CONCLUSION

Industry-specific information may be helpful in developing targeted tobacco-cessation programs.

Occupational exposure to silica dust and risk of lung cancer: an updated meta-analysis of epidemiological studies

BACKGROUND

Crystalline silica is considered as one of the most common and serious occupational hazards to workers' health. Although its association with lung cancer has been studied for many decades, the conclusion remains somewhat controversial. Our objectives are to review and summarize the epidemiological evidence on the relationship between occupational silica exposure and risk of lung cancer and to provide an update on this major occupational health concern.

METHODS

Eligible studies up to 29 April 2016 were identified. Pooled effect estimates were calculated according to the reported outcome and the study design. Cohort, case control and proportional mortality studies were examined separately. Studies reporting results according to silicotic status were grouped together and analyzed. Due to the significant amount of heterogeneity expected, random effects models were implemented. Subgroup and meta-regression analyses (both univariate and multivariate) were performed in an attempt to explain heterogeneity. Studies which had adequate exposure characterization were selected to find out whether there was an exposure-response relationship between silica and lung cancer.

RESULTS

The risk of lung cancer was found to be elevated in both silicotics and non-silicotics. The pooled standardized mortality ratio (SMR) was 2.32 with a 95 % confidence interval (95 % CI) of 1.91-2.81 and 1.78 (95 % CI 1.07-2.96) respectively. The pooled standardized incidence ratio (SIR) was 2.49 (95 % CI 1.87-3.33) and 1.18 (95 % CI 0.86-1.62) respectively. Subgroup analysis showed that workers in the mining industry had the highest risk of lung cancer with a pooled SMR of 1.48 (95 % CI 1.18-1.86) and the weakest association was seen in potteries with a pooled SMR of 1.14 (95 % CI 1.05-1.23). A positive exposure-response relation was found between cumulative silica exposure and risk of lung cancer.

CONCLUSION

The results of our meta-analysis supported the carcinogenic role of silica on the lungs, which was more pronounced at higher levels of exposure, in the presence of silicosis and in the mining industry. Further research is needed to evaluate whether non-silicotics are truly at risk, whether a predisposing factor would explain this potential risk, and to determine the mechanism of carcinogenicity of silica in humans.

Polymorphisms in Long Noncoding RNA H19 Contribute to the Protective Effects of Coal Workers' Pneumoconiosis in a Chinese Population

The H19 is a kind of long noncoding RNA, which has been implicated in multiple biological functions. However, the associations between genetic variants in H19 and susceptibility of coal workers' pneumoconiosis (CWP) have been seldom reported. In the present study, three potential polymorphisms (rs2067051, rs217727, and rs2839702) in H19 were genotyped in a case-control study including 703 CWP cases and 705 controls. We found that individuals with the H19 rs2067051 CT/TT genotypes showed a decreased risk of CWP compared with those with the CC genotype (adjusted OR = 0.64, 95%CI = 0.49-0.83, p = 0.001). Further stratified analyses revealed that the associations between variant genotypes of rs2067051 and the risk of CWP were more prominent in subjects of non-smokers (adjusted OR = 0.55, 95%CI = 0.39-0.79, p = 0.001) and CWP patients with Stage I (adjusted OR = 0.63, 95%CI = 0.46-0.86, p = 0.004). Additionally, the protective effects of H19 rs2067051 were also evident in coal miners both with dust exposure years <25 years (adjusted OR = 0.63, 95%CI = 0.42-0.95, p = 0.026) and ≥25 years (adjusted OR = 0.57, 95%CI = 0.40-0.80, p = 0.001). Our results indicated that rs2067051 in the H19 gene is correlated with a deceased risk of CWP in a Chinese population, which may be a potential genetic marker for prevention and intervention of CWP. Further functional studies are warranted to validate our findings.

Prognostic effect of tuberculosis on patients with occupational lung diseases: A 13-year observational study in a nationwide cohort

Occupational lung diseases are well recognized risk factors for tuberculosis (TB). However, little research investigated the effect of TB on the clinical course and outcome of occupational lung diseases.We conducted a 13-year observational study of a nationwide cohort to evaluate the risk and prognosis of TB among patients with occupational lung diseases in Taiwan.By using the Taiwan National Health Insurance database, occupational lung diseases cohort was identified according to diagnosis codes from 1998 to 2008 and prospectively monitored until the end of 2010, loss to follow-up, or death. Newly diagnosed TB, comorbidities, and demographic characteristics were evaluated as prognostic variables in the survival analysis of patients with occupational lung diseases using Cox proportional hazard regression models.A total of 12,787 study participants were enrolled with an average of 9.69 years of follow-up. Among them, 586 (4.58%) had newly diagnosed TB and 3180 (24.87%) died during follow-up. The incidence of TB was 473 per 100,000 person-years, and the risk of TB infection significantly increased over time. The independent risk factors for mortality included male gender (hazard ratio [HR]: 2.23, 95% confidence interval [CI]: 1.91-2.60), age (HR: 1.05, 95% CI: 1.05-1.06), TB (HR: 1.17, 95% CI: 1.01-1.37), congestive heart failure (HR: 1.44, 95% CI: 1.17-1.79), cerebrovascular disease (HR: 1.34, 95% CI: 1.15-1.57), chronic obstructive pulmonary disease (HR: 1.44, 95% CI: 1.33-1.56), and asthma (HR: 1.27, 95% CI: 1.15-1.40). In addition, patients with TB infections had worse outcomes in the survival analysis than those without TB (log-rank test P = 0.02).Despite the low prevalence of occupational lung diseases in Taiwan, patients with those diseases had a higher TB incidence than the general population did (473 vs 55 per 100,000 person-years). Furthermore, even with effective antimicrobial chemotherapy, TB infection was a prognostic factor leading to poor outcomes in the patients with occupational lung diseases. We recommend intensive medical surveillance of TB in these high-risk patients for better control of TB and improvement of occupational health in Taiwan.

Prevalence Characteristics of Coal Workers' Pneumoconiosis (CWP) in a State-Owned Mine in Eastern China

Coal Workers' Pneumoconiosis (CWP) is the primary occupational disease in China. However, information about the definite prevalence of CWP is only partially available. The aims of our study were to assess the prevalence characteristics of CWP in a state-owned coal mine, evaluate the effects of control measures and develop further preventive strategies for CWP. The total study population included 495 cases who were diagnosed with CWP from the construction of this coal mine to the end of October 2014. Individuals' information, including duration of dust exposure, job titles, age as first diagnosis, stages of CWP, CWP progress, complications with pulmonary tuberculosis, death and others were collected and analyzed. The results showed that 71.11% of 495 CWP cases were stage I and 90.71% were involved in tunneling or coal mining. The mean dust exposure period in CWP patients was 26.7 years, the mean latent period was 29.3 years and the mean diagnosed age was 50.3 years old. The proportion of CWP diagnosed after ending dust exposure were remarkably increased with the time passing. Among the CWP cases, 36 (7.27%) were complicated with pulmonary tuberculosis. The mortality of patients with stage III was the highest (60.71%) (p < 0.0001). Our data obviously show that more strict policies to protect coal miners are needed to be implemented in China, especially for tunneling and mining workers.