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

Update on Silicosis

Although silicosis has been an established disease with a recognized cause for more than 100 years, many workers continue to be exposed to silica and new outbreaks of disease continue to occur. This article describes some of the well-established and new exposures, including denim sandblasting, artificial stone cutting, and some forms of "coal worker's pneumoconiosis." The authors review the imaging and pathology of acute silicosis (silicoproteinosis), simple silicosis, and progressive massive fibrosis and summarize known and putative associations of silica exposure, including tuberculosis, lung cancer, connective tissue disease (especially systemic sclerosis), and vasculitis.

An umbrella review of the evidence associating occupational carcinogens and cancer risk at 19 anatomical sites

Occupational exposure to carcinogens of increasing cancer risk have been extensively suggested. A robust assessment of these evidence is needed to guide public policy and health care. We aimed to classify the strength of evidence for associations of 13 occupational carcinogens (OCs) and risk of cancers. We searched PubMed and Web of Science up to November 2022 to identify potentially relevant studies. We graded the evidence into convincing, highly suggestive, suggestive, weak, or not significant according to a standardized classification based on: random-effects p value, number of cancer cases, 95% confidence interval of largest study, heterogeneity between studies, 95% prediction interval, small study effect, excess significance bias and sensitivity analyses with credibility ceilings. The quality of meta-analysis was evaluated by AMSTAR 2. Forty-eight articles yielded 79 meta-analyses were included in current umbrella review. Evidence of associations were convincing (class I) or highly suggeastive (class II) for asbestos exposure and increasing risk of lung cancer among smokers (RR = 8.79, 95%CI: 5.81-13.25 for cohort studies and OR = 8.68, 95%CI: 5.68-13.24 for case-control studies), asbestos exposure and increasing risk of mesothelioma (RR = 4.61, 95%CI: 2.57-8.26), and formaldehyde exposure and increasing risk of sinonasal cancer (RR = 1.68, 95%CI: 1.38-2.05). Fifteen associations were supported by suggestive evidence (class III). In summary, the current umbrella review found strong associations between: asbestos exposure and increasing risk of lung cancer among smokers; asbestos exposure and increasing risk of mesothelioma; and formaldehyde exposure and higher risk of sinonasal cancer. Other associations might be genuine, but substantial uncertainty remains.

Differential pulmonary toxicity and autoantibody formation in genetically distinct mouse strains following combined exposure to silica and diesel exhaust particles

BACKGROUND

Inhalation of airborne particulate matter, such as silica and diesel exhaust particles, poses serious long-term respiratory and systemic health risks. Silica exposure can lead to silicosis and systemic autoimmune diseases, while DEP exposure is linked to asthma and cancer. Combined exposure to silica and DEP, common in mining, may have more severe effects. This study investigates the separate and combined effects of occupational-level silica and ambient-level DEP on lung injury, inflammation, and autoantibody formation in two genetically distinct mouse strains, thereby aiming at understanding the interplay between genetic susceptibility, particulate exposure, and disease outcomes. Silica and diesel exhaust particles were administered to mice via oropharyngeal aspiration. Assessments of lung injury and host response included in vivo lung micro-computed tomography, lung function tests, bronchoalveolar lavage fluid analysis including inflammatory cytokines and antinuclear antibodies, and histopathology with particle colocalization.

RESULTS

The findings highlight the distinct effects of silica and diesel exhaust particles (DEP) on lung injury, inflammation, and autoantibody formation in C57BL/6J and NOD/ShiLtJ mice. Silica exposure elicited a well-established inflammatory response marked by inflammatory infiltrates, release of cytokines, and chemokines, alongside mild fibrosis, indicated by collagen deposition in the lungs of both C57BL/6J and NOD/ShilLtJ mice. Notably, these strains exhibited divergent responses in terms of respiratory function and lung volumes, as assessed through micro-computed tomography. Additionally, silica exposure induced airway hyperreactivity and elevated antinuclear antibody levels in bronchoalveolar lavage fluid, particularly prominent in NOD/ShiLtJ mice. Moreover, antinuclear antibodies correlated with extent of lung inflammation in NOD/ShiLTJ mice. Lung tissue analysis revealed DEP loaded macrophages and co-localization of silica and DEP particles. However, aside from contributing to airway hyperreactivity specifically in NOD/ShiLtJ mice, the ambient-level DEP did not significantly amplify the effects induced by silica. There was no evidence of synergistic or additive interaction between these specific doses of silica and DEP in inducing lung damage or inflammation in either of the mouse strains.

CONCLUSION

Mouse strain variations exerted a substantial influence on the development of silica induced lung alterations. Furthermore, the additional impact of ambient-level DEP on these silica-induced effects was minimal.

Changing trends in disease burden of lung cancer in China from 1990-2019 and following 15-year prediction

BACKGROUND

As lung cancer becomes a primary source of death in China, investigation on incidence rate, death rate, and disability-adjusted life years (DALYs) is of great significance to optimize prevention measures and allocation of healthcare resources.

METHODS

We utilized data from the Global Burden of Disease (GBD) database to evaluate the incidence rate, death rate, and DALYs of lung cancer in China from 1990 to 2019. Analysis of lung cancer risk factor-related death rate and DALYs was performed. Age-standardized rates (ASR) and estimated annual percentage change (EAPC) were calculated. The incidence trend of lung cancer from 2020 to 2034 was predicted by the Nordpred age-period-cohort (APC) model.

RESULTS

Age-standardized incidence rate (ASIR) increased from 30.2/100000 (95 % UI 26.2-34.3) in 1990 to 41.7/100000 (95 % UI 35.2-48.8) in 2019, and EAPC was 1.33 (95 % CI 1.16-1.49). From 1990 to 2019, men were noted for the highest incidence rate, death rate, and DALYs rate across three age groups (15-49 years, 50-69 years, and over 70). During this period, the ASIR of lung cancer in females was always lower than that in males. The predominant risk factors of lung cancer were smoking, air pollution, and diet, among which smoking was the most significant one. The analysis results showed that new cases and deaths may increase in the following 15 years since 2020 in the context of lung cancer.

CONCLUSION

Faced with the heavy burden of lung cancer, China must issue corresponding policies and roll out prevention avenues against smoking and air pollution.

Lung cancer risk and occupational pulmonary fibrosis: systematic review and meta-analysis

BACKGROUND

Molecular pathways found to be important in pulmonary fibrosis are also involved in cancer pathogenesis, suggesting common pathways in the development of pulmonary fibrosis and lung cancer.

RESEARCH QUESTION

Is pulmonary fibrosis from exposure to occupational carcinogens an independent risk factor for lung cancer?

STUDY DESIGN AND METHODS

A comprehensive search of PubMed, Embase, Web of Science and Cochrane databases with over 100 search terms regarding occupational hazards causing pulmonary fibrosis was conducted. After screening and extraction, quality of evidence and eligibility criteria for meta-analysis were assessed. Meta-analysis was performed using a random-effects model.

RESULTS

52 studies were identified for systematic review. Meta-analysis of subgroups identified silicosis as a risk factor for lung cancer when investigating odds ratios for silicosis in autopsy studies (OR 1.47, 95% CI 1.13-1.90) and for lung cancer mortality in patients with silicosis (OR 3.21, 95% CI 2.67-3.87). Only considering studies with an adjustment for smoking as a confounder identified a significant increase in lung cancer risk (OR 1.58, 95% CI 1.34-1.87). However, due to a lack of studies including cumulative exposure, no adjustments could be included. In a qualitative review, no definitive conclusion could be reached for asbestosis and silicosis as independent risk factors for lung cancer, partly because the studies did not take cumulative exposure into account.

INTERPRETATION

This systematic review confirms the current knowledge regarding asbestosis and silicosis, indicating a higher risk of lung cancer in exposed individuals compared to exposed workers without fibrosis. These individuals should be monitored for lung cancer, especially when asbestosis or silicosis is present.

Occupational exposure to respirable crystalline silica and lung cancer: a systematic review of cut-off points

BACKGROUND

Respirable crystalline silica (RCS) is associated with the development of lung cancer. However, there is uncertainty around the exposure threshold at which exposure to RCS may pose a clear risk for the development of lung cancer. The objective of this study was to review the cut-off points at which the risk of mortality or incidence of lung cancer due to occupational exposure to RCS becomes evident through a systematic review.

METHODS

We conducted a search in PubMed, including cohort and case-control studies which assessed various categories of RCS exposure. A search was also conducted on the webpages of institutional organizations. A qualitative data synthesis was performed.

RESULTS

Twenty studies were included. Studies that assessed lung cancer mortality and incidence displayed wide variability both in RCS exposure categories and related risks. Although most studies found no significant association for RCS exposure categories, it appears to be a low risk of lung cancer for mean concentrations of less than 0.07mg/m3. Regulatory agencies set annual RCS exposure limits ranging from 0.025mg/m3 through 0.1mg/m3.

CONCLUSIONS

There is a wide degree of heterogeneity in RCS exposure categories, with most studies observing no significant risk of lung cancer for the lowest exposure categories. Cut-off points differ between agencies but are nonetheless very similar and do not exceed 0.1mg/m3.

Identifying the Environmental Determinants of Lung Cancer: A Case Study of Henan, China

Lung cancer has become one of the most prevalent cancers in the last several decades. Studies have documented that most cases of lung cancer are caused by inhaling environmental carcinogens while how external environmental factors lead to individual lung cancer is still an open issue as the pathogenesis may come from the combined action of multiple environmental factors, and such pathogenic mechanism may vary from region to region. Based on the data of lung cancer cases from hospitals at the county level in Henan from 2016 to 2020, we analyzed the response relationship between lung cancer incidence and physical ambient factors (air quality, meteorological conditions, soil vegetation) and socioeconomic factors (occupational environment, medical level, heating mode, smoking behavior). We used a Bayesian spatio-temporal interaction model to evaluate the relative risk of disease in different regions. The results showed that smoking was still the primary determinant of lung cancer, but the influence of air quality was increasing year by year, with meteorological conditions and occupational environment playing a synergistic role in this process. The high-risk areas were concentrated in the plains of East and Central Henan and the basin of South Henan, while the low-risk areas were concentrated in the hilly areas of North and West Henan, which were related to the topography of Henan. Our study provides a better understanding of the environmental determinants of lung cancer which will help refine existing prevention strategies and recognize the areas where actions are required to prevent environment and occupation related lung cancer.

Sociodemographic profile, work practices, and disease awareness among stone mine workers having silicosis from Central Rajasthan

Background and Objectives

Silicosis continues to pose an important health hazard among workers having occupational exposure to stone dust. Several studies have addressed clinical presentation, radiographic and pulmonary function abnormalities in workers with silicosis. This study was planned to analyze sociodemographic profile and awareness about several aspects of silicosis among the stone mine workers visiting our centre.

Methods

A questionnaire was administered in a convenient sample of eligible subjects over six years period. The questionnaire was aimed to collect sociodemographic variables, like age, gender, educational status, residential background, smoking status etc., apart from information on work-related profile including protective measures taken. Also knowledge and attitude regarding silicosis was assessed. Silicosis awareness index was also calculated as per the response received.

Results

Majority of the study subjects were male (96.6%) with rural background (98.5%). 54.1% subjects were in the age group of 30 to 50 years. 81.9% mine workers were illiterate. The common addictions observed among them included smoking (60%), tobacco chewing (34%), alcohol (20%) etc., Varying duration of work exposure was observed with more than 10 years in 63.4% and more than 20 years in 32.2% workers. The commonest work exposing them to stone dust was breaking stones by chisel and hammer (51%) followed by separation of stone slab (20%) and stone drilling (15%). 80.9% subjects were not aware of the term silicosis, more than 80% were not aware of the symptoms and causes of silicosis. Only one fifth subjects were having awareness of using protection against the disease. Overall awareness about silicosis was better among literate and youngers participants.

Conclusions

Stone mining industry reflects male dominance, poor literacy, long working hours for many years, financial compulsion to start and continue the job and very poor awareness regarding the disease silicosis and importance of personal protection at workplace.

The effect of silica exposure on the risk of lung cancer: A meta-analysis

Lung cancer is an incurable disease with an increased mortality rate caused by the inhalation of dust-containing crystalline silica particles. Silica exposure is one of the most important occupational hazards in the world. Whether the association between silica exposure and lung cancer is because of the fibrotic process or to the effect of respirable silica itself is unclear. The International Agency for Research on Cancer (IARC) classified silica as a human lung carcinogen. The opinion of lung cancer is a question that has been addressed in this review. Three electronic databases, including MEDLINE, Scopus, and Web of Science, were used to search for relevant literature from 2000 to 2022. To evaluate the relationship between exposure to silica and developing lung cancer, we performed a meta-analysis using the random-effects model. For each study, the overall odds ratio (OR), relative risk (RR) with 95% confidence intervals (CI), and p values were calculated. An extensive database search resulted in the selection of 20 (case-control and nested case-control studies were selected) out of 527 studies. Among the 20 selected studies, 7 studies showed a significant association between silica exposure and an increased risk of lung cancer. Further analysis showed that among the selected studies, six studies showed a significant correlation between combined exposure to silica and smoking with an increased risk of lung cancer. The data from the present study showed that smoking habits increased the impact of silica exposure on the initiation of lung carcinogenesis in exposed workers.

Crystalline silica-exposed human lung epithelial cells presented enhanced anchorage-independent growth with upregulated expression of BRD4 and EZH2 in autocrine and paracrine manners

Crystalline silica-induced inflammation possibly facilitates carcinogenesis. Here, we investigated its effect on lung epithelium damage. We prepared conditioned media of immortalized human bronchial epithelial cell lines (hereinafter bronchial cell lines) NL20, BEAS-2B, and 16HBE14o- pre-exposed to crystalline silica (autocrine crystalline silica conditioned medium), a phorbol myristate acetate-differentiated THP-1 macrophage line, and VA13 fibroblast line pre-exposed to crystalline silica (paracrine crystalline silica conditioned medium). As cigarette smoking imposes a combined effect on crystalline silica-induced carcinogenesis, a conditioned medium was also prepared using the tobacco carcinogen benzo[a]pyrene diol epoxide. Crystalline silica-exposed and growth-suppressed bronchial cell lines exhibited enhanced anchorage-independent growth in autocrine crystalline silica and benzo[a]pyrene diol epoxide conditioned medium compared with that in unexposed control conditioned medium. Crystalline silica-exposed nonadherent bronchial cell lines in autocrine crystalline silica and benzo[a]pyrene diol epoxide conditioned medium showed increased expression of cyclin A2, cdc2, and c-Myc, and of epigenetic regulators and enhancers, BRD4 and EZH2. Paracrine crystalline silica and benzo[a]pyrene diol epoxide conditioned medium also accelerated the growth of crystalline silica-exposed nonadherent bronchial cell lines. Culture supernatants of nonadherent NL20 and BEAS-2B in crystalline silica and benzo[a]pyrene diol epoxide conditioned medium had higher EGF concentrations, whereas those of nonadherent 16HBE14o- had higher TNF-α levels. Recombinant human EGF and TNF-α promoted anchorage-independent growth in all lines. Treatment with EGF and TNF-α neutralizing antibodies inhibited cell growth in crystalline silica conditioned medium. Recombinant human TNF-α induced BRD4 and EZH2 expression in nonadherent 16HBE14o-. The expression of γH2AX occasionally increased despite PARP1 upregulation in crystalline silica-exposed nonadherent lines with crystalline silica and benzo[a]pyrene diol epoxide conditioned medium. Collectively, crystalline silica- and benzo[a]pyrene diol epoxide-induced inflammatory microenvironments comprising upregulated EGF or TNF-α expression may promote crystalline silica-damaged nonadherent bronchial cell proliferation and oncogenic protein expression despite occasional γH2AX upregulation. Thus, carcinogenesis may be cooperatively aggravated by crystalline silica-induced inflammation and genotoxicity.

Altered M1/M2 polarization of alveolar macrophages is involved in the pathological responses of acute silicosis in rats in vivo

Alveolar macrophages play a vital role in the development of acute silicosis, but the dynamic changes of M1 and/or M2 phenotypes have not been elucidated. In this study, acute silicosis models of rat were established by a one-time dusting method, and the rats were sacrificed after 1, 3, 7, 14, and 28 days. The polarity states of macrophages were assessed by measuring the M1/M2 marker genes of alveolar macrophages and the M1/M2 marker proteins in bronchoalveolar lavage fluid. The pathological changes of lung tissues were examined with hematoxylin and Eosin and Masson’s trichrome staining. Our results showed that in the early stages, alveolar macrophages were mainly polarized into M1; with time, the polarization of M2 gradually became dominant. Microscopic sections showed significant pathological responses of inflammation and fibrosis. This work suggested that the alteration of alveolar macrophage polarization was involved in the lung pathologic responses to acute silicosis.

Trends and predictions of lung cancer incidence in Jiangsu Province, China, 2009–2030: a bayesian age-period-cohort modelling study

Background

Lung cancer is currently the most frequent cancer in Jiangsu Province, China, and the features of cancer distribution have changed continuously in the last decade. The aim of this study was to analyse the trend of the incidence of lung cancer in Jiangsu from 2009 to 2018 and predict the incidence from 2019 to 2030.

Methods

Data on lung cancer incidence in Jiangsu from 2009 to 2018 were retrieved from the Jiangsu Cancer Registry. The average annual percentage change (AAPC) was used to quantify the trend of the lung cancer age-standardized rate (ASR) using Joinpoint software. Bayesian age-period-cohort models were used to predict lung cancer incidence up to 2030.

Results

In Jiangsu, the lung cancer crude rate increased from 45.73 per 100,000 in 2009 to 69.93 per 100,000 in 2018. The lung cancer ASR increased from 29.03 per 100,000 to 34.22 per 100,000 during the same period (AAPC = 2.17%, 95% confidence interval [CI], 1.54%, 2.80%). Between 2019 and 2030, the lung cancer ASR is predicted to decrease slightly to 32.14 per 100,000 (95% highest density interval [HDI], 24.99, 40.22). Meanwhile, the ASR showed a downward trend in males and rural regions while remaining stable in females and urban regions.

Conclusion

We predict that the incidence of lung cancer in Jiangsu will decrease in the next 12 years, mainly due to the decrease in males and rural areas. Therefore, future lung cancer prevention and control efforts should be focused on females and urban regions.

Mortality among mine and mill workers exposed to respirable crystalline silica

BACKGROUND

Millions of workers are potentially exposed to respirable crystalline silica (RCS) which has been associated with several diseases. We updated the mortality experience of a cohort of 2,650 mine and mill workers at four manufacturing facilities to assess cause-specific mortality risks associated with estimated cumulative RCS exposure.

METHODS

Study eligibility was defined as any employee who had ≥1 year of service by 2000, with work history experience available from 1945 through 2004. Vital status and cause of death were ascertained from 1945 through 2015. RCS exposure was estimated across plant-, department-, job-, and time-dependent categories using historic industrial hygiene sampling data and professional judgment. Associations between cumulative RCS (mg/m3-years) and cause-specific mortality were examined using Cox proportional hazard regression models.

RESULTS

In the exposure-response analysis defined on quartiles of cumulative RCS exposure, no increasing trend (ptrend = 0.37) in lung cancer mortality (n = 116 deaths) was observed (Hazard ratio (HR) = 1.00 (referent), 1.20, 1.85, 0.92). Mortality risk for non-malignant respiratory disease was increased across quartiles (HR = 1.00, 1.35, 1.89, 1.70; ptrend = 0.15), based on 83 deaths. Non-malignant renal disease mortality was increased across quartiles (HR = 1.00, 6.64, 3.79, 3.29; ptrend = 0.11), based on 26 deaths.

CONCLUSIONS

After nearly seven decades of follow-up, the exposure-response analyses showed no evidence of a positive trend for lung cancer, and limited evidence of a trend for non-malignant respiratory disease, and non-malignant renal disease mortality as a result of cumulative RCS exposure in this occupational cohort.

Socio-economic deprivation and cancer incidence in England: Quantifying the role of smoking

BACKGROUND

More deprived populations typically experience higher cancer incidence rates and smoking prevalence compared to less deprived populations. We calculated the proportion of cancer cases attributable to smoking by socio-economic deprivation in England and estimated the impact smoking has on the deprivation gap for cancer incidence.

METHODS

Data for cancer incidence (2013-2017), smoking prevalence (2003-2007) and population estimates (2013-2017) were split by sex, age-group and deprivation quintile. Relative risk estimates from meta-analyses were used to estimate the population attributable fraction (PAF) for 15 cancer types associated with smoking. The deprivation gap was calculated using age-specific incidence rates by deprivation quintile.

RESULTS

Smoking-related cancer PAFs in England are 2.2 times larger in the most deprived quintile compared to the least deprived quintile (from 9.7% to 21.1%). If everyone had the same smoking prevalence as the least deprived quintile, 20% of the deprivation gap in cancer incidence could have been prevented. If nobody smoked, 61% of the deprivation gap could have been prevented.

CONCLUSIONS

The majority of the deprivation gap in cancer incidence could have been prevented in England between 2013-2017 if nobody had smoked. Policy makers should ensure that tobacco control policies reduce overall smoking prevalence by tackling smoking inequalities.

Lung cancer in never smokers: Tumor immunology and challenges for immunotherapy

Lung cancer is the second most common and the most lethal malignancy worldwide. It is estimated that lung cancer in never smokers (LCINS) accounts for 10-25% of cases, and its incidence is increasing according to recent data, although the reasons remain unclear. If considered alone, LCINS is the 7th most common cause of cancer death. These tumors occur more commonly in younger patients and females. LCINS tend to have a better prognosis, possibly due to a higher chance of bearing an actionable driver mutation, making them amenable to targeted therapy. Notwithstanding, these tumors respond poorly to immune checkpoint inhibitors (ICI). There are several putative explanations for the poor response to immunotherapy: low immunogenicity due to low tumor mutation burden and hence low MANA (mutation-associated neo-antigen) load, constitutive PD-L1 expression in response to driver mutated protein signaling, high expression of immunosuppressive factors by tumors cells (like CD39 and TGF-beta), non-permissive immune TME (tumor microenvironment), abnormal metabolism of amino acids and glucose, and impaired TLS (Tertiary Lymphoid Structures) organization. Finally, there is an increasing concern of offering ICI as first line therapy to these patients owing to several reports of severe toxicity when TKIs (tyrosine kinase inhibitors) are administered sequentially after ICI. Understanding the biology behind the immune response against these tumors is crucial to the development of better therapeutic strategies.

Short-term effects of indoor and outdoor air pollution on the lung cancer morbidity in Henan Province, Central China

Lung cancer is one of the most common cancer types and a major cause of death. The relationship between lung cancer morbidity and exposure to air pollutants is of particular concern. However, the relationship and difference in lung cancer morbidity between indoor and outdoor air pollution effects remain unclear. In this paper, the aim was to comprehensively investigate the spatial relationships between the lung cancer morbidity and indoor-outdoor air pollution in Henan based on the standard deviation ellipse, spatial autocorrelation analysis and GeoDetector. The results indicated that (1) the spatial distribution of lung cancer morbidity was related to the geomorphology, while high-morbidity areas were concentrated in the plains and basins of Central, Eastern and Southern Henan. (2) Among the selected outdoor air pollutants, PM_2.5, NO₂, SO₂, O₃ and CO were significantly correlated with the lung cancer morbidity. The degree of indoor air pollution was measured by the use of heating energy, and the proportions of coal-heating households, households with coal/biomass stoves and households with heated kangs were highly decisive in regard to the lung cancer morbidity. (3) The interaction between two factors was more notable than a single factor in explaining the lung cancer morbidity. Moreover, the interaction type was mainly nonlinear enhancement, and the proportion of households with coal/biomass stoves imposed the strongest interaction effect on the other factors.

Environmental and occupational exposure among cancer patients in Mato Grosso, Brazil

OBJECTIVE

To estimate the prevalence of occupational and environmental exposure according to sociodemographic factors in cancer patients treated at reference hospitals in the state of Mato Grosso, Brazil.

METHODS

This is a cross-sectional study on cancer patients aged 18 years or older. The prevalence of exposure to pesticides, asbestos, lead, heavy metals, formaldehyde, benzene, exposure to industrial dust, and handling of other chemical substances were calculated according to sex, age group, and level of education.

RESULTS

A total of 1,012 patients were interviewed (55.0% women, 45.6% aged 60 years or older, and 56.8% had less than five years of formal education). Pesticides (22.8%), industrial dust (10.7%), and benzene (10.1%) were the most frequent exposures. Occupational and environmental exposure was higher in men for all evaluated exposures, except for formaldehyde, which was higher in women. Exposure to pesticides, industrial dust, benzene, asbestos, and heavy metals increased with age and were more frequent among those with lower level of education.

CONCLUSION

Approximately one in five cancer patients treated at reference hospitals in Mato Grosso reported having been exposed to pesticides, and one in ten were exposed to industrial dust and benzene, with greater exposure among men, older individuals, and those with lower level of education.

Think Beyond Particle Cytotoxicity: When Self-Cellular Components Released After Immunogenic Cell Death Explain Chronic Disease Development

The prolonged perturbation of the immune system following the release of a plethora of self-molecules (known as damage-associated molecular patterns, DAMPs) by stressed or dying cells triggers acute and chronic pathological responses. DAMPs are commonly released after plasma membrane damage or complete rupture due to immunogenic cell death (ICD), upon numerous stressors including infectious and toxic agents. The set of DAMPs released after ICD include mature proinflammatory cytokines and alarmins, but also polymeric macromolecules. These self-intracellular components are recognized by injured and healthy surrounding cells via innate receptors, and induce upregulation of stress-response mechanisms, including inflammation. In this review, by overstepping the simple toxicological evaluation, we apply ICD and DAMP concepts to silica cytotoxicity, providing new insights on the mechanisms driving the progress and/or the exacerbation of certain SiO2–related pathologies. Finally, by proposing self-DNA as new crucial DAMP, we aim to pave the way for the development of innovative and easy-to-perform predictive tests to better identify the hazard of fine and ultrafine silica particles. Importantly, such mechanisms could be extended to nano/micro plastics and diesel particles, providing strategic advice and reports on their health issues.

Risk Assessment of Silicosis and Lung Cancer Mortality associated with Occupational Exposure to Crystalline Silica in Iran

BACKGROUND

Exposure to crystalline silica has long been identified to be associated with lung diseases. Therefore, the present study aimed to assess the risk of silicosis and lung cancer associated with occupational exposure to crystalline silica in Iran.

STUDY DESIGN

It is a systematic review study.

METHODS

Different databases were searched, and the Cochrane method was used for the systematic review. Thereafter, cumulative exposure to crystalline silica (mg/m3-y) was calculated in every industry. The relative risk of death from silicosis was performed using Mannetje's method. Based on the geometric mean of exposure, the lung cancer risk of exposure to crystalline silica was also calculated.

RESULTS

As evidenced by the results, worker's exposure to silica ranged from a geometric mean of 0.0212- 0.2689 mg/m3 (Recommended standard by the American Conference of Governmental Industrial Hygienists (ACGIH) was 0.025 mg/m3), which is generally higher than the occupational exposure limit recommended by National Institute for Occupational Safety and Health (NIOSH), ACGIH, and occupational exposure limits. The relative risk of silicosis was in the range of 1 to 14 per 1000 people, and the risk of lung cancer in workers ranged from 13-137 per 1000 people.

CONCLUSION

Since workers are at considerable risk of cancer due to exposure to silica in Iran, exposure control programs need to be implemented in workplaces to decrease the concentration of silica.

Global and national burden and trends of mortality and disability-adjusted life years for silicosis, from 1990 to 2019: results from the Global Burden of Disease study 2019

Background

Silicosis, as an important type of pneumoconiosis, leads to progressive and irreversible conditions from the beginning of inflammation and fibrosis. However, the data on the global burden of silicosis and long-term trends were limited.

Methods

Derived from the Global Burden of Disease study 2019 (online publicly available: Global Health Data Exchange), data on both crude and age-standardized rates (ASR) per 100,00 people of mortality and disability-adjusted life years (DALYs) due to silicosis was collected and analyzed. The burden and trends of mortality and DALYs due to silicosis was assessed by 204 countries and territories, by 5-year interval of age group and by sex from 1990 to 2019. And all the regions were divided into 5 categories according to Sociodemographic Index (SDI). Temporal trends in mortality and DALY were evaluated only to ASR by the Joinpoint regression model.

Results

More than 12.9 thousand [95% Uncertainty Intervals (UI): 10.9, 16.2] death cases occurred due to silicosis worldwide, and 655.7 thousand (95% UI: 519.3, 828.0) DALYs were attributed to silicosis in 2019. From 1990 to 2019, global number of mortality and DALYs in countries with high SDI quintile decreased by 0.35% (95% UI: − 0.45, − 0.17) and 0.32% (95% UI: − 0.45, − 0.01), respectively. There was a greater burden in low- and middle-income countries were estimated in 2019 according to ASRs. The global number of mortality and DALYs among males accounted for over 95% of all in 2019. Both age-sex-specific mortality and DALY rate were increasing with aging and reached their peak at 85–89 age group. During the past 30 years, ASR of mortality and DALYs showed a decreasing trend with average annual percentage change at -3.0% [95% Confidence Intervals (CI): − 3.2, − 2.9] and − 2.0 (95% CI: − 1.7, − 2.2), respectively.

Conclusions

Silicosis remains an important health issue and causes a potentially serious burden worldwide. Attention should be paid to making preventable, affordable and effective measures in lower SDI regions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-02040-9.

Silica nanoparticles induce pulmonary autophagy dysfunction and epithelial-to-mesenchymal transition via p62/NF-κB signaling pathway

It has been reported that silica nanoparticles (SiNPs) could cause epithelial-to-mesenchymal transition (EMT), but the specific mechanism is still unclear. Thus, the purpose of this study was to investigate the underlying mechanisms of pulmonary EMT after subacute exposure to SiNPs. The results showed intratracheal instillation of SiNPs increased the pulmonary MDA content, while decreased the activity of SOD and GSH-Px in rats. Western blot analysis demonstrated that SiNPs induced autophagy dysfunction via the upregulation of p62. Meanwhile, the inflammation cytokines (TNF-α, IL-18, IL-1β) were released in rat lung. Immunohistochemistry and western blot assays both showed that SiNPs could regulate the related protein biomarkers of EMT through decreasing E-cadherin and increasing vimentin in a dose-dependent manner. Besides, SiNPs activated the proteins expression involved in p62/NF-κB signaling pathway, whereas the pulmonary EMT induced by SiNPs was significantly dampened after the knock down of p62. In this study, we illustrated that subacute exposure to SiNPs could trigger the autophagy dysfunction and pulmonary inflammation, further lead to EMT via activating the p62/NF-κB signaling pathway. Our findings provide new molecular evidence for SiNPs-induced pulmonary toxicity.

Distribution and sources of PM2.5-bound free silica in the atmosphere of hyper-arid regions in Hotan, North-West China

The composition of atmospheric fine particulate matter (PM_2.5) is complex and exhibits strong regional differences. Free silica (α-SiO₂) in atmospheric particulate matter is carcinogenic and is an important component of respirable particulate matter in urban areas. Measurements determined that the concentration of silicon dioxide (α-SiO₂) in PM_2.5 in the urban area of Hotan City, China, was 8.02 μg·m^-3 during the dust period and exceeded 1.77 μg·m^-3 during the non-dust period. The proportion of α-SiO₂ in PM_2.5 was 8.07% during the dust period and 2.25% during the non-dust period. Atmospheric visibility during the dust period was mainly influenced by the content of atmospheric floating dust. Analysis of α-SiO₂ pollution sources during the dust period showed that the air masses containing sand and dust originated from the desert hinterland. Following passage through oasis areas, the air mass was effectively reduced in the concentration of α-SiO₂ in PM_2.5. During the dusty period, α-SiO₂ and PM_2.5 originated from the same source in Hotan City. Moreover, wind speed was the main influencing factor for the α-SiO₂ concentration. During the non-dust period, α-SiO₂ and PM_2.5 were not from the same source of pollution.

Silica-associated systemic lupus erythematosus with lupus nephritis and lupus pneumonitis: A case report and a systematic review of the literature

INTRODUCTION

Several epidemiological studies have shown that silica exposure triggers the onset of systemic lupus erythematosus (SLE); however, the clinical characteristics of silica-associated SLE have not been well studied.

PATIENT CONCERNS

A 67-year-old man with silicosis visited a primary hospital because of a fever and cough. His respiratory condition worsened, regardless of antibiotic medication, and he was referred to our hospital.

DIAGNOSIS

The patient showed leukopenia, lymphopenia, serum creatinine elevation with proteinuria and hematuria, decreased serum C3 level, and was positive for anti-double stranded DNA antibody, anti-nuclear antibody, and direct Coombs test. He was diagnosed with SLE. Renal biopsy was performed, and the patient was diagnosed with lupus nephritis (class IV-G(A/C) + V defined by the International Society of Nephrology/Renal Pathology Society classification). Computed tomography revealed acute interstitial pneumonitis, bronchoalveolar lavage fluid showed elevation of the lymphocyte fraction, and he was diagnosed with lupus pneumonitis.

INTERVENTIONS

Prednisolone (50 mg/day) with intravenous cyclophosphamide (500 mg/body) were initiated.

OUTCOMES

The patient showed a favorable response to these therapies. He was discharged from our hospital and received outpatient care with prednisolone slowly tapered off. He had cytomegalovirus and herpes zoster virus infections during treatment, which healed with antiviral therapy.

REVIEW

We searched for the literature on sSLE, and selected 11 case reports and 2 population-based studies. The prevalence of SLE manifestations in sSLE patients were comparative to that of general SLE, particularly that of elderly-onset SLE. Our renal biopsy report and previous reports indicate that lupus nephritis of sSLE patients show as various histological patterns as those of general SLE patients. Among the twenty sSLE patients reported in the case articles, three patients developed lupus pneumonitis and two of them died of it. Moreover, two patients died of bacterial pneumonia, one developed aspergillus abscesses, one got pulmonary tuberculosis, and one developed lung cancer.

CONCLUSION

Close attention is needed, particularly for respiratory system events and infectious diseases, when treating patients with silica-associated SLE using immunosuppressive therapies.

Occupational Exposure to Mineral Dust in Mining and Earthmoving Works: A Scoping Review

Anthropogenic activity is related to several environmental imbalances, including dust. Particulate matter can also hinder humans with numerous health consequences, such as asthma, cancer, and pneumoconiosis. With a particular focus on mineral dust, this review is intended to determine in which circumstances occupational exposure occurs in the mining and earthmoving industries. Research followed the guidelines provided by the preferred reporting items for systematic review and meta-analysis protocols and its extension for scoping reviews. Of the 8993 records identified, only 24 passed both exclusion and inclusion criteria. Within the pool of results, it was possible to identify the following variables related to dust exposure: job-related (activity, job category, and site), engineering (equipment, transport system), technical (distance), and physical (season and weather) variables. Due to the significant variance in protocol settings, it was challenging to perform a general analysis, resulting in a study-by-study approach. The most significant conclusion of this study is not related to the setting of occupational exposure, although it derives from it. The necessity of adopting standard procedures for data collection, independent of research objective, was demonstrated within the context of occupational exposure to mineral dust.

Exposição ocupacional e câncer: uma revisão guarda-chuva

Resumo Objetivo: fornecer uma visão geral das associações entre exposição ocupacional e risco da ocorrência ou morte por câncer. Métodos: esta revisão guarda-chuva da literatura utilizou as bases Medline e Web of Science. A partir de protocolo de busca, foram incluídas metanálises para diversas circunstâncias ocupacionais e cânceres selecionados que possuíssem algum nível de evidência para associação com ocupação. Resultados: foram incluídas 37 metanálises, abrangendo 18 localizações de câncer. Considerando a avaliação da heterogeneidade dos estudos, da qualidade da evidência e da força de associação, obteve-se evidências altamente sugestivas de associações entre exposição a solvente e mieloma múltiplo; amianto e câncer de pulmão; hidrocarbonetos e câncer de trato aerodigestivo superior; e estresse ocupacional e câncer colorretal. Conclusão: há evidências robustas para associar exposições ocupacionais e tipos de câncer não previstos, inicialmente, nas orientações de vigilância do câncer relacionado ao trabalho no Brasil. Permanecem lacunas sobre exposições de grande relevância, que carecem de metanálises mais consistentes, por exemplo, exposição a poeiras inorgânicas e câncer de pulmão e mesotelioma; exposição a solventes e tumores hematológicos. Evidências de câncer em outras regiões anatômicas foram menos robustas, apresentando indícios de incerteza ou viés.

Mortality in the cohort of talc miners and millers from Val Chisone, Northern Italy: 74 years of follow-up

OBJECTIVE

To update the analysis of mortality of a cohort of talc miners and millers in Northern Italy.

METHODS

We analyzed overall mortality and mortality from specific causes of death during 1946-2020 of 1749 male workers in a talc mine where asbestos was not detected (1184 miners and 565 millers) employed during 1946-1995.

RESULTS

The overall standardized mortality ratio (SMR) was 1.21 (95 % confidence interval [CI] 1.14-1.28); no deaths were observed from pleural cancer. Mortality from lung cancer was not increased (SMR = 1.02 95 % CI 0.82-1.27), while mortality from pneumoconiosis was (SMR 9.55; 95 % CI 7.43-12.08), especially among miners (SMR 12.74; 95 % CI 9.79-16.31). There was a trend in risk of pneumoconiosis with increasing duration of employment in the overall cohort, and the SMR for 25+ years of employment was 15.12 (95 % CI 10.89-20.43).

CONCLUSIONS

This uniquely long-term follow up confirms the results of previous analyses, namely the lack of association between exposure to talc with no detectable level of asbestos and lung cancer and mesothelioma. Increased mortality from pneumoconiosis among miners is related to past exposure to silica.

Exposição ambiental e ocupacional entre pacientes com câncer em Mato Grosso

RESUMO: Objetivo: Estimar a prevalência da exposição ocupacional e ambiental segundo fatores sociodemográficos nos pacientes com câncer atendidos nos hospitais de referência do estado de Mato Grosso. Métodos: Estudo transversal com pacientes com câncer de 18 anos ou mais. Foram calculadas as prevalências de exposição a agrotóxicos, amianto, chumbo, metais pesados, formol, benzeno e poeira industrial e de manuseio de outras substâncias químicas conforme sexo, faixa etária e escolaridade. Resultados: Foram entrevistados 1.012 pacientes (55,0% do sexo feminino, 45,6% com 60 anos ou mais, 56,9% com menos de cinco anos de escolaridade). Agrotóxicos (22,8%), poeira industrial (10,7%) e benzeno (10,1%) foram as exposições de maior frequência. A exposição ocupacional e ambiental foi maior no sexo masculino para todas as exposições avaliadas, exceto para o formol, que foi maior no sexo feminino. A exposição a agrotóxico, poeira industrial, benzeno, amianto e metais pesados aumentou com a idade e foi mais frequente entre aqueles de menor escolaridade. Conclusão: Aproximadamente um em cada cinco pacientes com câncer atendidos em hospitais de referência de Mato Grosso relatou ter sido exposto aos agrotóxicos, e um a cada dez foi exposto a poeira industrial e benzeno, sendo maior a exposição entre os indivíduos do sexo masculino, mais velhos e de menor escolaridade.

Occupational exposure and cancer: an umbrella review

Abstract Objective: to provide an overview of the associations between occupational exposure and risk of occurrence or death from cancer. Methods: this umbrella review used the Medline and Web of Science databases. Based on the search protocol, meta-analysis was included for several occupational circumstances and selected cancers that had some level of evidence associated with the occupation. Results: 37 meta-analysis were included, covering 18 cancer locations. By assessing the heterogeneity of studies, quality of evidence, and strength of association, results highly indicated associations between solvent exposure and multiple myeloma, asbestos and lung cancer, hydrocarbons and upper aerodigestive tract cancer, occupational stress and colorectal cancer. Conclusion: robust evidence shows an association between occupational exposures and types of cancer not initially foreseen in the guidelines for work-related cancer surveillance in Brazil. Gaps in relevant exposures require further research and more consistent meta-analysis, including: exposure to inorganic dust and lung cancer and mesothelioma; solvents and hematological tumors. Evidence of cancer in other anatomical regions was less robust, showing signs of uncertainty or bias.

Mental health in mine workers: a literature review

The mining environment is hazardous for worker's health. It can affect the mental health, triggering symptoms and diseases, such as anxiety, job stress, depression, sleep disorders, mental fatigue and other. The aim of this study was to describe and analyze the scientific literature about the mental health in mine workers and to summarize the findings. The method used was scoping review. The principal outcomes were the following: evidence in the last 12 years in the topic was focused in four themes 1) Psychological problems & personal factors (38.2%); 2) Psychosocial problems & health related factor (23.6%); 3) Well-being (21.1%) and 4) Physical problems & organization factors (17.1%). Several affections, symptoms, characteristics or disorders were inquired about mine worker's mental health, such as job strain, unsafety experiences, poor quality of sleep, non-subjective well-being, job unsatisfaction, social-relations conflict, risk of accidents and injuries, musculoskeletal disorders (MSDs), substance abuse, dangerous working conditions and demanding job organization, and so on. For those factors, Mining could expose to serious mental health problems to a part of their workers. It's necessary to deepen the elaboration of international policies and carry out more scientific research and suggestions to make programs on the topic.

The effect of silica exposure on the risk of lung cancer: A dose-response meta-analysis

BACKGROUND

The relationship between silica and the risk of developing lung cancer has been established in previous literature, but how much the level of exposure to silica can increase the risk of lung cancer is a question that has been addressed in this review.

METHODS

Three electronic databases, including MEDLINE, Scopus, and Web of Science were searched for relevant literature. For the dose-response relationship between exposure to silica and developing lung cancer, we performed a meta-analysis using the random-effects model. For each level of exposure, we calculated the overall risk ratio (RR) with 95% confidence intervals (CI).

RESULTS

Nineteen studies were included in the meta-analysis. There was a positive and significant increasing dose-response trend between silica exposure and the risk of developing lung cancer as follows: < 0.50 mg/m³ 1.14 (95% CI: 1.05, 1.23; I² = 79%), 0.50-0.99 mg/m³ 1.34 (95% CI: 1.05, 171; I² = 45%), 1.00-1.99 mg/m³ 1.14 (95% CI: 1.00, 1.30; I² = 70%), 2.00-2.99 mg/m³ 1.47 (95% CI: 1.05, 2.06; I² = 57%), 3.00-3.99 mg/m³ 1.44 (95% CI: 0.99, 2.11; I² = 58%), and ≥ 4.00 mg/m³ 1.64 (95% CI: 1.20, 2.24; I² = 88%). The heterogeneity across studies was mild to moderate.

CONCLUSIONS

The presence of a dose-response relationship favors the causal relationship between exposure to silica and developing lung cancer.

De Novo Powered Air-Purifying Respirator Design and Fabrication for Pandemic Response

The rapid spread of COVID-19 and disruption of normal supply chains has resulted in severe shortages of personal protective equipment (PPE), particularly devices with few suppliers such as powered air-purifying respirators (PAPRs). A scarcity of information describing design and performance criteria for PAPRs represents a substantial barrier to mitigating shortages. We sought to apply open-source product development (OSPD) to PAPRs to enable alternative sources of supply and further innovation. We describe the design, prototyping, validation, and user testing of locally manufactured, modular, PAPR components, including filter cartridges and blower units, developed by the Greater Boston Pandemic Fabrication Team (PanFab). Two designs, one with a fully custom-made filter and blower unit housing, and the other with commercially available variants (the “Custom” and “Commercial” designs, respectively) were developed; the components in the Custom design are interchangeable with those in Commercial design, although the form factor differs. The engineering performance of the prototypes was measured and safety validated using National Institutes for Occupational Safety and Health (NIOSH)-equivalent tests on apparatus available under pandemic conditions at university laboratories. Feedback was obtained from four individuals; two clinicians working in ambulatory clinical care and two research technical staff for whom PAPR use is standard occupational PPE; these individuals were asked to compare PanFab prototypes to commercial PAPRs from the perspective of usability and suggest areas for improvement. Respondents rated the PanFab Custom PAPR a 4 to 5 on a 5 Likert-scale 1) as compared to current PPE options, 2) for the sense of security with use in a clinical setting, and 3) for comfort compared to standard, commercially available PAPRs. The three other versions of the designs (with a Commercial blower unit, filter, or both) performed favorably, with survey responses consisting of scores ranging from 3 to 5. Engineering testing and clinical feedback demonstrate that the PanFab designs represent favorable alternatives to traditional PAPRs in terms of user comfort, mobility, and sense of security. A nonrestrictive license promotes innovation in respiratory protection for current and future medical emergencies.

Pulmonary function parameters among marble industry workers in Lahore, Pakistan

Background: Occupational contact with dust particles is a well-known phenomenon, particularly in developing countries of the world. Crystalline silica present in marble dust is the main etiology of a rising prevalence of obstructive lung diseases in marble stone workers, who are in direct contact with marble dust in the surrounding environment during their regular work.  The purpose of this study was to compare the pulmonary function parameters of workers in marble workshops and age matched healthy individuals in the Lahore District of Pakistan. Methods: The study included 164 male individuals, 82 individuals working in marble workshops and 82 healthy individuals from the same community. Data were collected through in-person interviews using a structured questionnaire after obtaining written consent. A Spiro Lab spirometry for pulmonary function tests was used to identify any change in the lung function parameters. FVC% (forced vital capacity), FEV 1 (forced expiratory volume in first second) and FEV1 / FVC ratio were evaluated. Results: Mean age in the exposed group (marble workers) and non-exposed group (healthy individuals) were 29.92 ± 6.19 and 30.58 ± 6.37 years, respectively. The mean years of work experience of the exposed group was 11.92 ± 5.67 years. A statistically insignificant difference was observed between marble exposed workers & healthy individuals from the demographic variables. Lung function parameters in marble workers exhibited a highly significant (P < 0.001) decrease in FVC%, FEV 1 & FEV 1 / FVC ratio when compared to healthy individuals. Seventy-one percent of marble workers had abnormal pulmonary parameters whereas 34% of workers had restrictive pulmonary impairment. Marble workers who had worked for more than 15 years had a highly significant risk of developing abnormal pulmonary function (P < 0.001). Conclusion: Continuous exposure to marble dust deteriorates the lung function of marble workers.

Rapid Induction of Pulmonary Inflammation, Autoimmune Gene Expression, and Ectopic Lymphoid Neogenesis Following Acute Silica Exposure in Lupus-Prone Mice

Occupational exposure to crystalline silica (cSiO2) is etiologically associated with systemic lupus erythematosus (lupus) and other autoimmune diseases. cSiO2's autoimmune effects in humans can be mimicked chronically in female lupus-prone NZBWF1 mice following repeated exposure to the particle. However, the immediate and short-term effects of cSiO2 in this widely used model of autoimmune disease are not well-understood. In the present study, we tested the hypothesis that a single acute cSiO2 dose triggers early presentation of cellular, histopathological, transcriptomic, and protein biomarkers of inflammation and autoimmunity in lupus-prone mice. Eight-week old female NZBWF1 mice were intranasally instilled once with 2.5 mg cSiO2 or saline vehicle and necropsied at 1, 7, 14, 21, and 28 d post-instillation (PI). Analyses of bronchoalveolar lavage fluid (BALF) and lung tissue revealed that by 7 d PI, acute cSiO2 exposure persistently provoked: (i) robust recruitment of macrophages, neutrophils, and lymphocytes into the alveoli, (ii) cell death as reflected by increased protein, double-stranded DNA, and lactate dehydrogenase activity, (iii) elevated secretion of the cytokines IL-1α, IL-1β, IL-18, TNF-α, IL-6, MCP-1, and B cell activation factor (BAFF), and (iv) upregulation of genes associated with chemokines, proinflammatory cytokines, lymphocyte activation, and type I interferon signaling. The appearance of these endpoints was subsequently followed by the emergence in the lung of organized CD3+ T cells (14 d PI) and CD45R+ B cells (21 d PI) that were indicative of ectopic lymphoid structure (ELS) development. Taken together, acute cSiO2 exposure triggered a rapid onset of autoimmune disease pathogenesis that was heralded in the lung by unresolved inflammation and cell death, proinflammatory cytokine production, chemokine-driven recruitment of leukocytes, an interferon response signature, B and T cell activation, and ELS neogenesis. This short-term murine model provides valuable new insight into potential early mechanisms of cSiO2-induced lupus flaring and, furthermore, offers a rapid venue for evaluating interventions against respirable particle-triggered inflammation and autoimmunity.

Mortality in Underground Miners in a Former Uranium Ore Mine–Results of a Cohort Study Among Former Employees of Wismut AG in Saxony and Thuringia

BACKGROUND

From 1946 to 1990, more than 400 000 people were employed by Wismut AG, a Soviet/Soviet-German corporation (German abbreviation: SAG/ SDAG), in the East German states of Saxony and Thuringia. In the early years in particular, employees were exposed to large amounts of radon and respirable crystalline silica.

METHODS

In a cohort of 35 204 former underground employees of Wismut AG, mortality was analyzed in comparison to the general male population of East Germany, and the pertaining standardized mortality ratios (SMRs) were calculated.

RESULTS

18 510 persons in the study cohort died in the follow-up period 1960-2013. Mortality from lung cancer was 2.36 higher in the study cohort than in the general population (95% confidence interval, [2.28; 2.45]); the associated SMRs rose markedly with increasing radon exposure. Mortality from silicosis and other types of pneumoconiosis was elevated by a factor of 22.62 [21.20; 24.11], and the associated SMRs rose exponentially with increasing exposure to respirable crystalline silica. Mortality from both of these causes was still markedly elevated more than 20 years after Wismut AG had ceased its activities. Mortality from a wide range of other diseases was elevated as well, with the following SMRs: stomach cancer, 1.28 [1.17; 1.40]; liver cancer, 1.34 [1.15; 1.55]; all tumors other than lung cancer, 1.06 [1.02; 1.09]; infections, 1.18 [1.01; 1.38]; cerebrovascular diseases, 1.33 [1.26; 1.41]; and influenza/pneumonia, 1.13 [1.01; 1.27]. Mortality from a small number of other causes was found to be markedly lowered in the study cohort (mental illness, renal diseases, and nervous system diseases). The role of occupational risk factors, lifestyle differences and other reasons for the latter results is unclear.

CONCLUSION

Underground miners employed by Wismut AG displayed marked excess mortality due to silicosis/other pneumoconiosis and lung cancer. The contribution of individual occupational risk factors for these and other causes of death with increased SMR are being further investigated in analyses within the study cohort.

Occupational lung diseases in the 21st century: the changing landscape and future challenges

PURPOSE OF REVIEW

Occupational exposures remain an underrecognized and preventable cause of lung disease in high-income countries. The present review highlights the emergence of cleaning-related respiratory disease and the re-emergence of silicosis as examples of trends in occupational lung diseases in the 21st century.

RECENT FINDINGS

Employment trends, such as the shift from large-scale manufacturing to a service economy, the growth of the healthcare sector, and changing consumer products have changed the spectrum of work-related lung diseases. Following decades of progress in reducing traditional hazards such as silica in U.S. workplaces, cases of advanced silicosis have recently re-emerged with the production of engineered stone countertops. With growth in the healthcare and service sectors in the United States, cleaning products have become an important cause of work-related asthma and have recently been associated with an increased risk of chronic obstructive pulmonary disease (COPD) in women. However, these occupational lung diseases largely go unrecognized by practicing clinicians.

SUMMARY

The present article highlights how changes in the economy and work structure can lead to new patterns of inhalational workplace hazards and respiratory disease, including cleaning-related respiratory disease and silicosis. Pulmonary clinicians need to be able to recognize and diagnose these occupational lung diseases, which requires a high index of suspicion and a careful occupational history.

Respirable Crystalline Silica Exposure, Smoking, and Lung Cancer Subtype Risks. A Pooled Analysis of Case-Control Studies

Rationale: Millions of workers around the world are exposed to respirable crystalline silica. Although silica is a confirmed human lung carcinogen, little is known regarding the cancer risks associated with low levels of exposure and risks by cancer subtype. However, little is known regarding the disease risks associated with low levels of exposure and risks by cancer subtype.Objectives: We aimed to address current knowledge gaps in lung cancer risks associated with low levels of occupational silica exposure and the joint effects of smoking and silica exposure on lung cancer risks.Methods: Subjects from 14 case-control studies from Europe and Canada with detailed smoking and occupational histories were pooled. A quantitative job-exposure matrix was used to estimate silica exposure by occupation, time period, and geographical region. Logistic regression models were used to estimate exposure-disease associations and the joint effects of silica exposure and smoking on risk of lung cancer. Stratified analyses by smoking history and cancer subtypes were also performed.Measurements and Main Results: Our study included 16,901 cases and 20,965 control subjects. Lung cancer odds ratios ranged from 1.15 (95% confidence interval, 1.04-1.27) to 1.45 (95% confidence interval, 1.31-1.60) for groups with the lowest and highest cumulative exposure, respectively. Increasing cumulative silica exposure was associated (P trend < 0.01) with increasing lung cancer risks in nonsilicotics and in current, former, and never-smokers. Increasing exposure was also associated (P trend ≤ 0.01) with increasing risks of lung adenocarcinoma, squamous cell carcinoma, and small cell carcinoma. Supermultiplicative interaction of silica exposure and smoking was observed on overall lung cancer risks; superadditive effects were observed in risks of lung cancer and all three included subtypes.Conclusions: Silica exposure is associated with lung cancer at low exposure levels. An exposure-response relationship was robust and present regardless of smoking, silicosis status, and cancer subtype.

Nanoparticle exposure and hazard in the ceramic industry: an overview of potential sources, toxicity and health effects

The ceramic industry is an industrial sector of great impact in the global economy that has been benefiting from advances in materials and processing technologies. Ceramic manufacturing has a strong potential for airborne particle formation and emission, namely of ultrafine particles (UFP) and nanoparticles (NP), meaning that workers of those industries are at risk of potential exposure to these particles. At present, little is known on the impact of engineered nanoparticles (ENP) on the environment and human health and no established Occupational Exposure Limits (OEL) or specific regulations to airborne nanoparticles (ANP) exposure exist raising concerns about the possible consequences of such exposure. In this paper, we provide an overview of the current knowledge on occupational exposure to NP in the ceramic industry and their impact on human health. Possible sources and exposure scenarios, a summary of the existing methods for evaluation and monitoring of ANP in the workplace environment and proposed Nano Reference Values (NRV) for different classes of NP are presented. Case studies on occupational exposure to ANP generated at different stages of the ceramic manufacturing process are described. Finally, the toxicological potential of intentional and unintentional ANP that have been identified in the ceramic industry workplace environment is discussed based on the existing evidence from in vitro and in vivo inhalation toxicity studies.

Association between early informed diagnosis and survival time in patients with lung cancer

OBJECTIVE

As a malignant tumor with high mortality, lung cancer (LC) often causes great trauma to patients, and a series of negative emotions and a heavy psychological burden accompanies poor prognosis. Whether or not to inform the patients of their condition has always been a controversial topic in the medical community. This retrospective cohort study investigated the association between early informed diagnosis and survival time in patients with LC.

METHODS

A total of 29 825 patients with LC were enrolled between October 2002 and December 2016. The potential factors influencing LC survival were registered, including knowing their cancer diagnosis status, age, gender, pathological type, clinical stage, surgical history, hospital grade, and patient occupation. All participants were followed up every 6 months until June 2017.

RESULTS

In June 2017, 23.1% of the participants still survived. Their median survival time (MST) was 11.20 months (95% confidence interval [CI], 10.98-11.43). Generally, patients that knew their cancer diagnosis had longer MST than those who did not (18.33 months vs 8.77 months, P < .001). By stratified analysis, patients that knew their cancer diagnosis had longer survival time in each subgroup (P < .001, all subgroups). Cox regression analysis showed that knowing their cancer diagnosis was an independent influencing factor for survival in patients with LC (hazard ratio, 0.826; 95% CI, 0.802-0.851; P < .001).

CONCLUSIONS

Knowing their cancer diagnosis contributed to longer survival time in patients with LC, providing clear evidence that medical staff and patients' families should fully disclose cancer diagnoses to patients.

Predictive model for the diagnosis of benign/malignant small pulmonary nodules

There is some doubt that all nodules <8 mm are really mainly benign and that simple follow-up is adequate in all cases. The purpose of this study is to create a predictive model for the diagnosis of benign and malignant small pulmonary nodules.This was a retrospective case-control study of patients who had undergone pulmonary nodule resection at the Zhejiang University Jinhua Hospital. Patients with pulmonary nodules of ≤10 mm in size on chest high-resolution computed tomography were included. Patients' demographic characteristics, clinical features, and high-resolution computed tomography findings were collected. Logistic regression and receiver-operating characteristic analysis were used to create a predictive model for malignancy.A total of 216 patients were included: 160 with malignant and 56 with benign nodules. Nodule density (odds ratio [OR] = 0.996, 95% confidence interval [CI]: 0.993-0.998, P = .001), vascular penetration sign (OR = 3.49, 95% CI: 1.39-8.76, P = .008), nodule type (OR = 4.27, 95% CI: 1.48-12.29, P = .007), and incisure surrounding nodules (OR = 0.18, 95% CI: 0.04-0.84, P = .03) were independently associated with malignant nodules. These factors were used to create a mathematical model that had an area under the receiver-operating characteristic curve of 0.744. Using a cut-off of 0.762 resulted in 63.1% sensitivity and 75.0% specificity.This study proposes a pulmonary nodule prediction model that can estimate benign/malignant lung nodules with good sensitivity and specificity. Mixed ground-glass nodules, vascular penetration sign, density of lung nodules, and the absence of incisure signs are independently associated with malignant lung nodules.

Silica and asbestos exposure at work and the risk of bladder cancer in Canadian men: a population-based case-control study

Background

Silica and asbestos are recognized lung carcinogens. However, their role in carcinogenesis at other organs is less clear. Clearance of inhaled silica particles and asbestos fibers from the lungs may lead to translocation to sites such as the bladder where they may initiate carcinogenesis. We used data from a Canadian population-based case-control study to evaluate the associations between these workplace exposures and bladder cancer.

Methods

Data from a population-based case-control study were used to characterize associations between workplace exposure to silica and asbestos and bladder cancer among men. Bladder cancer cases (N = 658) and age-frequency matched controls (N = 1360) were recruited within the National Enhanced Cancer Surveillance System from eight Canadian provinces (1994–97). Exposure concentration, frequency and reliability for silica and asbestos were assigned to each job, based on lifetime occupational histories, using a combination of job-exposure profiles and expert review. Exposure was modeled as ever/never, highest attained concentration, duration (years), highest attained frequency (% worktime) and cumulative exposure. Odds ratios (OR) and their 95% confidence intervals (CI) were estimated using adjusted logistic regression.

Results

A modest (approximately 20%) increase in bladder cancer risk was found for ever having been exposed to silica, highest attained concentration and frequency of exposure but this increase was not statistically significant. Relative to unexposed, the odds of bladder cancer were 1.41 (95%CI: 1.01–1.98) times higher among men exposed to silica at work for ≥27 years. For asbestos, relative to unexposed, an increased risk of bladder cancer was observed for those first exposed ≥20 years ago (OR:2.04, 95%CI:1.25–3.34), those with a frequency of exposure of 5–30% of worktime (OR:1.45, 95%CI:1.06–1.98), and for those with < 10 years of exposure at low concentrations (OR:1.75, 95%CI:1.10–2.77) and the lower tertile of cumulative exposure (OR:1.69, 95%CI:1.07–2.65). However, no clear exposure-response relationships emerged.

Conclusions

Our results indicate a slight increase in risk of bladder cancer with exposure to silica and asbestos, suggesting that the effects of these agents are broader than currently recognized. The findings from this study inform evidence-based action to enhance cancer prevention efforts, particularly for workers in industries with regular exposure.

Caplan's Syndrome with a twist

Caplan's syndrome is seen in patients with rheumatoid arthritis (RA) and chronic silica inhalation. We present a patient with RA who presented with multiple pulmonary nodules. Biopsy of the nodules revealed silica crystals under polarized light. He continued treatment for RA and his pulmonary nodules remained stable. However, he subsequently developed renal failure with nephrotic range proteinuria. We discuss silica and the associated autoimmunity in patients with chronic occupational exposure.

BACKGROUND

Caplan's syndrome also known as rheumatoid pneumoconiosis is a disease entity that is seen in patients with rheumatoid arthritis (RA) exposed to chronic silica and inorganic dust [1,2]. Classically, they form peripheral well-defined pulmonary nodules with characteristic silica retained in the necrobiotic center. In addition, epidemiological data has shown some association with silica and autoimmunity [3]. We present a case of silica and asbestosis exposure in a patient with rheumatoid arthritis who developed rheumatoid pneumoconiosis and subsequent renal failure. We highlight this rare disease, progression as well as other associated complications.

Lung cancer related to occupational exposure: an integrative review

ABSTRACT Objective: To identify in the literature the carcinogenic agents found in the work environment, the occupations and the risk for lung cancer. Method: A descriptive and analytical study of the Integrative Literature Review type was carried out in national and international databases from the last ten years in the period from 2009 to 2018, concerning 32 studies referring to association between carcinogenic substances to which the worker is exposed and lung cancer. Results: Nine (28.1%) publications originated in China and only one in Brazil. The most exposed workers were from the secondary sector, 50% being from industry and 6.2% from construction, mostly male. Asbestos and silica stood out among the carcinogenic substances most associated with lung cancer risk, accounting for 37.5% and 28.1%, respectively. Conclusions: The association between occupational exposure and the risk for lung cancer was characterized in this research by the substantial scientific evidence from the described studies that confirm this association.

Silicosis in rhinestone-manufacturing workers in South China

BACKGROUND

Silicosis is caused by long-term exposure to silica dust. Crystal rhinestone workers can be exposed to high levels of silica dust and are at risk of silicosis.

AIMS

To explore silicosis cases, silica dust exposure and control measures in a rhinestone factory in South China.

METHODS

We extracted and analysed data on new silicosis cases reported to China's occupational disease and occupational health information monitoring system between 2006 and 2012 from a rhinestone factory in South China. We measured the quartz content of bulk dust, static total and respirable dust samples.

RESULTS

Ninety-eight silicosis cases were reported between 2006 and 2012. The mean duration of silica dust exposure was 9.2 years (range 3-16). Drilling and polishing workers accounted for 96 (98%) of cases. We collected 1479 static samples including 690 total dust and 789 respirable dust samples. Mean dust levels for drilling were 1.01 mg/m3 (range 0.20-3.80) for total dust and 0.51 mg/m3 (range 0.04-1.70) for respirable dust. Mean dust levels for polishing were 0.59 mg/m3 (range 0.20-2.10) for total dust and 0.28 mg/m3 (range 0.08-0.71) for respirable dust. Over a third [289/789 (37%)] of total dust samples and 129/690 (19%) respirable dust samples exceeded the national permissible exposure limit.

CONCLUSION

Exposure to silica dust, ineffective dust control measures and inefficient health surveillance may have contributed to the incidence of silicosis in the factory we studied. Identification of silica dust exposure and effective dust control measures would reduce the risk of silicosis in rhinestone workers.

Effects of commodity on the risk of emphysema in South African miners

PURPOSE

To examine associations between mine commodity such as coal, platinum, or diamonds and emphysema among South African miners at autopsy.

METHODS

We examined the association between mine commodity and emphysema using the Pathology Automation (PATHAUT) database, 1975-2014. Exposure was characterized as longest tenure in each commodity. We constructed separate multivariable logistic regression models for black and white miners. Smoking was assessed in a sub-analysis of white miners.

RESULTS

Among black miners, coal mining was significantly associated with increased odds of emphysema [OR = 2.39 (95% CI 1.86, 3.07)] when compared to gold mining. Asbestos was also associated with significantly increased odds of emphysema among black miners [OR = 1.47 (95% CI 1.01, 2.12)]. No associations between commodity and emphysema were observed among white miners. Cumulative years of exposure and age at death were significant predictors for emphysema for both black and white miners. Smoking was a significant predictor of emphysema in the sub-analysis of white miners with smoking information, but no effect of commodity was observed.

CONCLUSIONS

We observed a significant association between coal mining and emphysema among black miners. Adverse health effects of coal mining are evidenced by more than twofold increase in emphysema among black coal miners compared to gold miners. This suggests that South African Coal miners are exposed to high dust concentrations or more damaging components compared to other commodities, resulting in elevated risk of emphysema.

The effect of single and combined exposures to magnetite and polymorphous silicon dioxide nanoparticles on the human A549 cell line: in vitro study

The increasing trend of nanoparticle usage in science and technology has led to significant human exposure. Occupational exposure to iron oxides and silica dust has been reported in mining, manufacturing, construction, and pharmaceutical operations. The combined toxicological effects of nanoparticles and simultaneous exposure to other compounds have given rise to a new concern. Hence, the objective of this study was to investigate the toxicological effects of magnetite and polymorphous silicon dioxide nanoparticles in single and combined exposures. The polymorphous silicon dioxide nanoparticles were obtained from the milled quartz particles under 100 nm in diameter. The milled particles were purified through chloric and nitric acid wash processes. The toxic effects of the magnetite nanoparticles were investigated independently and in combination with quartz using the A₅₄₉ cell line for durations of 24 and 72 h, and using diverse concentrations of 10, 50, 100, and 250 μg/mL. MTT, ROS, mitochondrial membrane potential, and cell glutathione content assays were used to evaluate the amount of cell damage in this study. The statistical significance level in one-way ANOVA and independent t test was considered to be at the 5% confidence level. The size and purity of polymorphous silicon dioxide nanoparticles were measured by TEM and ICP-OES analysis, respectively. The particles' diameters were under 100 nm and demonstrated a purity of higher than 99%. The toxicity results of this study showed a dependency on concentration and exposure duration in reducing the cell viability, cellular glutathione content, and mitochondrial membrane potential, as well as increasing the ROS generation in single and combined exposures with magnetite and polymorphous silicon dioxide nanoparticles. The toxic effects of combined exposure to these nanoparticles were less than the single exposures, and statistically significant antagonistic interactions were detected. Combined exposure to polymorphous silicon dioxide and magnetite nanoparticles, in comparison with their single exposures, could affect health in an antagonistic manner. Since this study has been the first of its kind, further studies investigating the health effects of single and combined exposures to these compounds are needed to verify our findings. Generally, studies such as this one could contribute to the field of combined toxicity effects.

A Bayesian assessment of occupational health surveillance in workers exposed to silica in the energy and construction industry

Medical records generated during occupational health surveillance processes have large amounts of unexploited information that can help to reduce silica-related health risks and many occupational diseases. The methodology applied in this study consists in analyzing through machine learning techniques a database with 70,000 medical examinations from workers in the energy and construction industry in Spain. First, a general unsupervised Bayesian model is built and node force analysis is used to identify the factors with the greatest impact on the worker's health surveillance process. Second, a predictive Bayesian model is created and mutual information is employed to assess the more relevant factors affecting the medical capability of workers exposed to silica dust. The lung auscultation and the breathing exploration are the two factors that influence the most the medical capability of silica-exposed employees. Probabilistic inference shows a remarkable gender effect, where women present more resilience towards occupational diseases than men showing a higher proportion of normal results in certain key factors, such as body mass index (♀49.73%, ♂25.17%) or spirometry (♀53.73%, ♂48.91%). Finally, environmental conditions demonstrate to have a major influence on spatial variability of occupational diseases. The design of health prevention programs based on geographical variations can be crucial to the attainment of an ongoing and sustained healthier workforce with a reduction in the number of chronic workplace illnesses.

Passive personal air sampling of dust in a working environment-A pilot study

The aim of this study was to make a preliminary evaluation of the University of North Carolina passive aerosol sampler (UNC sampler) for personal air sampling of particles. Nine personal air samplings of respirable fraction were conducted in an open-pit mine, with pairwise UNC samplers and a respirable cyclone mounted on the chest of workers. UNC samples were analyzed with scanning electron microscopy (SEM) and to some extent energy dispersive X-ray spectroscopy (EDS). Respirable cyclone filter samples were weighed. Correlations and particle elemental compositions were described. Microscopic imaging of the collection surface showed that the particles were heterogeneously deposited across the surface of the UNC sampler. Collected particles were shaped as gravel particles and the resulting particle size distribution in air showed a peak at ca. 3 µm aerodynamic diameter, similarly to what has previously been reported from the same mine. The elemental composition indicated mineral origin. All correlations between the airborne mass concentrations from UNC samplers and respirable cyclones (Pearson = 0.54 and Spearman = 0.43) and between pairs of parallel UNC samplers (Pearson = 0.55 and Spearman = 0.67) were weak. The UNC sampler mass concentrations were approximately 30 times higher than those measured with the respirable cyclone. In conclusion, the UNC sampler, when used for personal sampling in a mine, provides a reasonable particle size distribution and the deposited particles appeared to be of mineral origin and not from textile or skin but the approximately 30-fold overestimation of mass concentrations when comparing with respirable cyclone sampling indicates that further improvements are necessary. Positioning of the sampler may be critical and moving the UNC sampler from the chest to e.g. the top of a helmet might be an improvement. Grounding of the sampler in order to avoid static electricity might also be useful. The UNC sampler should continue to be researched for personal sampling, as passive sampling might become a useful alternative to more laborious sampling techniques.

Investigation of foreign materials in gingival lesions: a clinicopathologic, energy-dispersive microanalysis of the lesions and in vitro confirmation of pro-inflammatory effects of the foreign materials

OBJECTIVES

This study aimed to evaluate the clinical and histopathologic features of gingival lesions containing foreign material (GLFMs). In parallel, the composition of the foreign material and its effects in primary human gingival fibroblasts (HGFs) were investigated.

STUDY DESIGN

Eighty-six GLFMs were retrieved from an oral pathology biopsy service. Clinical and microscopic data were analyzed, and the composition of the particles was identified by using energy-dispersive X-ray spectroscopy (EDX). Furthermore, HGFs were stimulated with silica (SiO₂) microparticles to investigate the production of collagen type 1 (COL-1), matrix metalloproteinase 2 (MMP2), and inflammatory cytokines.

RESULTS

GLFMs were most commonly found in women (60.5%) and most frequently described as white plaques. Histopathologic examination identified verrucous hyperplasia in 59% and epithelial dysplasia in 28% of the cases. EDX microanalysis revealed that Si (94%) was the most frequently detected foreign element. SiO₂ microparticles induced higher COL-1 expression; higher levels of proinflammatory cytokines, such as interleukin-6 (IL-6), IL-8, and transforming growth factor-β, and increased MMP-2 activity in HGFs.

CONCLUSIONS

There was a strong association between the presence of foreign material in the gingiva and white verrucous clinical lesions. In addition, the most common element in the foreign material was Si, and our in vitro findings demonstrate the importance of silica-mediated effects on gingival fibroblasts.

Occupational Lung Disease

Occupational exposures are a major cause of lung disease and disability worldwide. This article reviews the broad range of types of occupational lung diseases, including airways disease, pneumoconioses, and cancer. Common causes of occupational lung disease are reviewed with specific examples and clinical features. Emphasis on the importance of a detailed history to make an accurate diagnosis of an occupational lung disease is discussed.

Risk Analysis Implications of Dose-Response Thresholds for NLRP3 Inflammasome-Mediated Diseases: Respirable Crystalline Silica and Lung Cancer as an Example

Chronic inflammation mediates an extraordinarily wide range of diseases. Recent progress in understanding intracellular inflammasome assembly, priming, activation, cytokine signaling, and interactions with mitochondrial reactive oxygen species, lysosome disruption, cell death, and prion-like polymerization and spread of inflammasomes among cells, has potentially profound implications for dose-response modeling. This article discusses mechanisms of exposure concentration and duration thresholds for NOD-like receptor protein 3 (NLRP3)-mediated inflammatory responses and develops a simple biomathematical model of the onset of exposure-related tissue-level chronic inflammation and resulting disease risks, focusing on respirable crystalline silica (RCS) and lung cancer risk as an example. An inflammation-mediated 2-stage clonal expansion model of RCS-induced lung cancer is proposed that explains why relatively low estimated concentrations of RCS (eg, <1 mg/m³) do not increase lung cancer risk and why even high occupational concentrations increase risk only modestly (typically relative risk <2). The model of chronic inflammation implies a dose-response threshold for excess cancer risk, in contrast to traditional linear-no-threshold assumptions. If this implication is correct, then concentrations of crystalline silica (or amphibole asbestos fibers, or other environmental challenges that act via the NLRP3 inflammasome) below the threshold do not cause chronic inflammation and resulting elevated risks of inflammation-mediated diseases.