Long-term effects of aluminium dust inhalation

Prospective findings from the Dongfeng-Tongji cohort: Exposure to various metals, the expression of microRNA-4286, and the incidence of acute coronary syndrome

Mounting evidence suggests that metal/metalloid exposure is related to the adverse health effects. Our prior investigation revealed a positive relation between the plasma level of microRNA-4286 (miR-4286) and an increased risk of developing acute coronary syndrome (ACS). However, it is a lack of studies evaluating the connection between metal/metalloid exposure and miRNA expression on ACS. In the prospective Dongfeng-Tongji cohort, we performed a nested case-control study. A total of 480 ACS and 480 controls were carefully selected based on similar age, sex, and blood collection time. Using inductively coupled plasma mass spectrometry, we assessed the plasma concentrations of 24 different metals. Quantitative real-time polymerase chain reaction was used to analyze the plasma miR-4286. We examined the relations of plasma metals with miR-4286 levels, the incidence of ACS, and the potential interactions. Using the multivariate conditional logistic regression models, we observed that the adjusted odds ratios (95% confidence intervals [CI]) for incident ACS were 1.79 (1.03, 3.12; P-trend = 0.03), 0.60 (0.41, 0.87; P-trend = 0.008), and 0.66 (0.46, 0.93; P-trend = 0.02), when comparing the extreme tertiles of aluminum, rubidium, and selenium, respectively. There was a relation between the concentration of rubidium in plasma and a decrease in the level of plasma miR-4286 (percent difference [95% CI]: -13.36% [-22.74%, -2.83%]; P-trend = 0.01). Both multiplicative (P interaction = 0.009) and additive interactions (relative excess risk due to interaction [95% CI]: 0.82 [0.59, 1.06]) were noted in our observation regarding the relationship between plasma aluminum and miR-4286 in incident ACS. The findings indicated that plasma aluminum was positively while plasma rubidium and selenium were negatively linked to an increased risk of developing ACS. Plasma aluminum exposure and plasma miR-4286 expression might synergistically affect the incident ACS risk. Controlling aluminum exposure was important for ACS prevention, especially for individuals with high expression of plasma miR-4286.

A Bayesian network for estimating hypertension risk due to occupational aluminum exposure

Background

The correlation between metals and hypertension, such as sodium, zinc, potassium, and magnesium, has been confirmed, while the relationship between aluminum and hypertension is not very clear. This study aimed to evaluate the correlation between plasma aluminum and hypertension in electrolytic aluminum workers by the Bayesian networks (BN).

Methods

In 2019, 476 male workers in an aluminum factory were investigated. The plasma aluminum concentration of workers was measured by inductively coupled plasma mass spectrometry. The influencing factors on the prevalence of hypertension were analyzed by the BN.

Results

The prevalence of hypertension was 23.9% in 476 male workers. The risk of hypertension from plasma aluminum in the Q2, Q3, and Q4 groups was 5.20 (1.90-14.25), 6.92 (2.51-19.08), and 7.33 (2.69-20.01), respectively, compared with that in the Q1 group. The risk of hypertension from the duration of exposure to aluminum of >10 years was 2.23 (1.09-4.57), compared without aluminum exposure. Area under the curve was 0.80 of plasma aluminum and the duration of exposure to aluminum was based on covariates, indicating that aluminum exposure had important predictive value in the prevalence of hypertension in the occupational population. The results of the study using the BN model showed that if the plasma aluminum of all participants was higher than Q4 (≥47.86 µg/L) and the participants were drinking, smoking, diabetes, central obesity, dyslipidemia, and aged >50 years, the proportion of hypertension was 71.2%.

Conclusions

The prevalence of hypertension increased significantly with the increase of plasma aluminum level.

Occupational exposure to vapors, gasses, dusts, and fumes in relation to causes of death during 24 years in Helsinki, Finland

PURPOSE

Environmental particulate matter (PM) exposure has been shown to cause excess all-cause and disease-specific mortality. Our aim was to compare disease-specific mortality by estimated occupational exposure to vapors, gasses, dusts, and fumes (VGDF).

METHODS

The data source is the Helsinki part of the population-based FinEsS study on chronic obstructive pulmonary diseases including information on age, education level, main occupation, sex, and tobacco smoking combined with death registry information. We compared estimated VGDF exposure to mortality using adjusted competing-risks regression for disease-specific survival analysis for a 24-year follow-up.

RESULTS

Compared to the no-exposure group, the high occupational VGDF exposure group had sub-hazard ratios (sHR) of 1.7 (95% CI 1.3-2.2) for all cardiovascular-related and sHR 2.1 (1.5-3.9) for just coronary artery-related mortality. It also had sHR 1.7 (1.0-2.8) for Alzheimer's or vascular dementia-related mortality and sHR 1.7(1.2-2.4) for all respiratory disease-related mortality.

CONCLUSION

Long-term occupational exposure to VGDF increased the hazard of mortality- to cardiovascular-, respiratory-, and dementia-related causes. This emphasizes the need for minimizing occupational long-term respiratory exposure to dust, gasses, and fumes.

A review of the epidemiological and laboratory evidence of the role of aluminum exposure in pathogenesis of cardiovascular diseases

The objective of the present study was to review the epidemiological and laboratory evidence on the role of aluminum (Al) exposure in the pathogenesis of cardiovascular diseases. Epidemiological data demonstrated an increased incidence of cardiovascular diseases (CVD), including hypertension and atherosclerosis in occupationally exposed subjects and hemodialysis patients. In addition, Al body burden was found to be elevated in patients with coronary heart disease, hypertension, and dyslipidemia. Laboratory studies demonstrated that Al exposure induced significant ultrastructural damage in the heart, resulting in electrocardiogram alterations in association with cardiomyocyte necrosis and apoptosis, inflammation, oxidative stress, inflammation, and mitochondrial dysfunction. In agreement with the epidemiological findings, laboratory data demonstrated dyslipidemia upon Al exposure, resulting from impaired hepatic lipid catabolism, as well as promotion of low-density lipoprotein oxidation. Al was also shown to inhibit paraoxonase 1 activity and to induce endothelial dysfunction and adhesion molecule expression, further promoting atherogenesis. The role of Al in hypertension was shown to be mediated by up-regulation of NADPH-oxidase, inhibition of nitric oxide bioavailability, and stimulation of renin-angiotensin-aldosterone system. It has been also demonstrated that Al exposure targets cerebral vasculature, which may be considered a link between Al exposure and cerebrovascular diseases. Findings from other tissues lend support that ferroptosis, pyroptosis, endoplasmic reticulum stress, and modulation of gut microbiome and metabolome are involved in the development of CVD upon Al exposure. A better understanding of the role of the cardiovascular system as a target for Al toxicity will be useful for risk assessment and the development of treatment and prevention strategies.

Selenium and zinc supplementation mitigates metals-(loids) mixture- mediated cardiopulmonary toxicity via attenuation of antioxidant, anti-inflammatory and antiapoptotic mechanisms in female Sprague Dawley rats

This study evaluated the cardiopulmonary protective effects of essential elements (Zn and Se) against heavy metals mixture (HMM) exposure. Twenty five female Sprague Dawley albino rats, divided in to five groups: controls were orally treated only with distilled water; next, group 2 was exposed to HMM with the following concentrations: 20 mg/kg of Pb body weight, 0.40 mg/kg of Hg, 0.56 mg/kg of Mn, and 35 mg/kg of Al. Groups 3, 4 and 5 were exposed to HMM and co-treated with zinc chloride (ZnCl2; 0.80 mg/kg), sodium selenite (Na2SeO3;1.50 mg/kg) and both zinc chloride and sodium selenite, respectively. The experiment lasted for 60 days. Afterwards animals were sacrificed, and we conduced biochemical and histopathological examination of the heart and lungs. HMM only exposed animals had an increased levels of malondialdehyde (MDA) and nitric oxide (NO), increased IL-6 and TNF-α, attenuated SOD, GPx, CAT and GSH and caspase 3 in the heart and lungs. HMM affected NF-kB and Nrf2 in the heart muscle with histomorphological alterations. Zn and Se attenuated adverse effects of HMM exposure. Essential element supplementation ameliorated heavy metal cardiopulmonary intoxication in rats.

Effect of E. cava and C. indicum Complex Extract on Phorbol 12-Myristate 13-Acetate (PMA)-Stimulated Inflammatory Response in Human Pulmonary Epithelial Cells and Particulate Matter (PM)2.5-Induced Pulmonary Inflammation in Mice

This study explores the potential of a natural composite formulation known as ED, consisting of Ecklonia cava (E. cava, family: Lessoniaceae) and Chrysanthemum indicum Linne (C. indicum, family: Asteraceae), in alleviating lung inflammation induced by fine particulate matter (PM2.5). Initial assessments confirmed that neither ED nor one of its components, dieckol, exhibited cytotoxic effects on A549 cells. Subsequently, the impact of ED and dieckol on MUC5AC gene expression in A549 cells stimulated by phorbol 12-myristate 13-acetate (PMA) was investigated, revealing promising results that demonstrated a dose-dependent inhibition of MUC5AC gene expression. The study also delves into the underlying mechanisms, demonstrating that ED and dieckol effectively suppressed the phosphorylation of mitogen-activated protein kinases (MAPKs), including JNK, ERK, and p38, which are known to be involved in the regulation of MUC5AC gene expression. In in vivo experiments using a PM2.5-induced pulmonary inflammation mouse model, the research findings showed that ED mitigated cellular accumulation in the airways, leading to a significant reduction in the total cell count in bronchoalveolar lavage fluid (BALF). Moreover, ED exhibited protective effects against PM2.5-induced pulmonary damage, characterized by reduced inflammatory cell infiltration and decreased mucus secretion in pulmonary tissues. Additionally, ED's anti-inflammatory properties were evident in its ability to decrease the levels of key inflammatory cytokines, TNF-α and IL-6, both in the serum and lung tissue of the PM2.5-induced pulmonary inflammation mouse model. These findings suggest the potential of ED as a therapeutic agent for inflammatory respiratory diseases.

miRNAs and Stem Cells as Promising Diagnostic and Therapeutic Targets for Alzheimer's Disease

Alzheimer's disease (AD) is a cumulative progressive neurodegenerative disease characterized mainly by impairment in cognitive functions accompanied by memory loss, disturbance in behavior and personality, and difficulties in learning. Although the main causes of AD pathogenesis are not fully understood yet, amyloid-β peptides and tau proteins are supposed to be responsible for AD onset and pathogenesis. Various demographic, genetic, and environmental risk factors are involved in AD onset and pathogenesis such as age, gender, several genes, lipids, malnutrition, and poor diet. Significant changes were observed in microRNA (miRNA) levels between normal and AD cases giving hope for a diagnostic procedure for AD through a simple blood test. As yet, only two classes of AD therapeutic drugs are approved by FDA. They are classified as acetylcholinesterase inhibitors and N-methyl-D-aspartate antagonists (NMDA). Unfortunately, they can only treat the symptoms but cannot cure AD or stop its progression. New therapeutic approaches were developed for AD treatment including acitretin due to its ability to cross blood-brain barrier in the brain of rats and mice and induce the expression of ADAM 10 gene, the α-secretase of human amyloid-β protein precursor, stimulating the non-amyloidogenic pathway for amyloid-β protein precursor processing resulting in amyloid-β reduction. Also stem cells may have a crucial role in AD treatment as they can improve cognitive functions and memory in AD rats through regeneration of damaged neurons. This review spotlights on promising diagnostic techniques such as miRNAs and therapeutic approaches such as acitretin and/or stem cells keeping in consideration AD pathogenesis, stages, symptoms, and risk factors.

Associations between plasma metal mixture exposure and risk of hypertension: A cross-sectional study among adults in Shenzhen, China

Background

Metal exposure affects human health. Current studies mainly focus on the individual health effect of metal exposure on hypertension (HTN), and the results remain controversial. Moreover, the studies assessing overall effect of metal mixtures on hypertension risk are limited.

Methods

A cross-sectional study was conducted by recruiting 1,546 Chinese adults who attended routine medical check-ups at the Eighth Affiliated Hospital of Sun Yat-sen University, Shenzhen. The plasma levels of 13 metals were measured using inductively coupled plasma mass spectrometry. Multivariate logistic regression model, restricted cubic spline (RCS) model and the Bayesian Kernel Machine Regression (BKMR) model were applied to explore the single and combined effect of metals on the risk of HTN.

Results

A total of 642 (41.5%) participants were diagnosed with HTN. In the logistic regression model, the adjusted odds ratios (ORs) were 0.71 (0.52, 0.97) for cobalt, 1.40 (1.04, 1.89) for calcium, 0.66 (0.48, 0.90), and 0.60 (0.43, 0.83) for aluminum in the second and third quartile, respectively. The RCS analysis showed a V-shaped or an inverse V-shaped dose-response relationship between metals (aluminum or calcium, respectively) and the risk of HTN (P for non-linearity was 0.017 or 0.009, respectively). However, no combined effect was found between metal mixture and the risk of hypertension.

Conclusions

Plasma levels of cobalt, aluminum and calcium were found to be associated with the risk of HTN. Further studies are needed to confirm our findings and their potential mechanisms with prospective studies and experimental study designs.

McIntyre Powder and its potential contributions to cardiovascular disease risk: A literature review through the McIntyre Powder historical lens

McIntyre Powder (MP) is a fine aluminum powder that was developed to prevent silicosis in gold and uranium mine workers in Ontario, Canada, and was administered to miners there from 1943 to 1979. Mine workers were exposed to high concentrations (35.6 mg/m³) of MP for approximately 10 min before every work shift. Contemporary physical and chemical characterizations of this powder have revealed that 12% of the powder is in the ultrafine particle size‐range (nanoparticles); and the remaining 88%, in the fine particulate size range (below 2.5 µm in diameter). The confluence of ultrafine particulate (UFP) composition and high airborne concentration of MP would be expected to overwhelm the defense mechanisms of the lung and increase the lung dust burden of the mine worker exposed to respirable dust in the mine. Published studies revealing associations between air pollution particulates and increased risk for cardiovascular disease (CVD) shown a dose–response relationship with ambient PM_2.5 and UFP and suggest that miners exposed to MP may also be at increased risk of CVD. The historical perspective of the use of MP in northern Ontario hard‐rock mines and its potential implications for CVD in exposed mine workers are discussed.

Blood pressure mediated the effects of cognitive function impairment related to aluminum exposure in Chinese aluminum smelting workers

OBJECTIVES

The aim of this study is to investigate the effects that the Al on blood pressure and the effect of hypertension in aluminum-induced cognitive impairment in electrolytic aluminum worker.

METHODS

The study was conducted 392 male aluminum electrolytic workers in an aluminum plant of China. The concentration of alumina dust in the air of the electrolytic aluminum workshop is 1.07mg/m3-2.13mg/m3. According to the Permissible concentration-Time Weighted Average of alumina dust is 4mg/ m3, which does not exceed the standard. The blood pressure of the workers was measured. The plasma aluminum concentration of workers was determined by ICP-MS (Inductively Coupled Plasma Mass Spectrometry). Cognitive functions were measured using MMSE (Mini-Mental State Examination), VFT (Verbal Fluency Test), ATIME (Average Reaction Time), FOM (Fuld Object Memory Evaluation), DST (Digit Span Test), CDT (Clock Drawing Test) scales. Modified Poisson regression was used to analyze the risk of hypertension and cognitive impairment with different plasma aluminum concentrations. Generalized linear regression model was used to analyze the relationship between aluminum and cognitive function, blood pressure and cognitive function. Causal Mediation Analysis was used to analyze the mediation effect of blood press in aluminum-induced cognitive impairment.

RESULTS

Plasma aluminum appeared to be a risk factor for hypertension (PR (prevalence ratio) = 1.630, 95%-CI (confidence interval): 1.103 to 2.407), systolic blood pressure (PR = 1.578, 95%-CI: 1.038 to 2.399) and diastolic blood pressure (PR = 1.842, 95%-CI: 1.153 to 2.944). And plasma aluminum increased by e-fold, the scores of MMSE and VFT decreased by 0.630 and 2.231 units respectively and the time of ATIME increased by 0.029 units. In addition, generalized linear regression model showed that blood press was negatively correlated with the scores of MMSE and VFT. Finally, causal Mediation Analysis showed that hypertension was a part of the mediating factors of aluminum-induced decline in MMSE score, and the mediating effects was 16.300% (7.100%, 33.200%). In addition, hypertension was a part of the mediating factors of aluminum-induced decline in VFT score, and the mediating effects was 9.400% (2.600%, 29.000%) CONCLUSION: Occupational aluminum exposure increases the risk of hypertension and cognitive impairment. And hypertension may be a mediating factor of cognitive impairment caused by aluminum exposure.

Sarcoidosis in Northern Ontario hard-rock miners: A case series

Sarcoidosis is a rare multisystem granulomatous disease traditionally considered to be of unknown etiology. The notion that sarcoidosis has no known cause is called into question with the increasing number of case reports and epidemiologic studies showing associations between occupational exposures and disease published in the past 10-20 years. Occupational exposures for which associations are strongest and most consistent are silica and other inorganic dusts, World Trade Center (WTC) dust, and metals. Occupations identified as at-risk for sarcoidosis include construction workers; iron-foundry and diatomaceous earth workers; WTC emergency responders; and metal workers. We report here 12 cases of sarcoidosis in a cohort of hard-rock miners in Northern Ontario, Canada. To our knowledge sarcoidosis has not been reported previously in hard-rock miners. The cases are all male and Caucasian, with average age 74 years. At the time of diagnosis, two were never smokers; six, former smokers; and four, current smokers. Five have extrapulmonary sarcoidosis: two cardiac and three endocrine (hypercalciuria). Using occupational histories and air sampling data from the gold, uranium, and base-metal mines in which they worked, we examined exposure of each case to respirable crystalline silica (RCS). The annual mean RCS exposure for the 12 cases was 0.14 mg/m³ (range: 0.06-1.3 mg/m³ ); and the mean cumulative RCS exposure was 1.93 mg/m³  years (range: 0.64-4.03 mg/m³  years). We also considered their exposure to McIntyre Powder, an aluminum powder used for silicosis prophylaxis.

Investigation of metals accumulation in soil dumpsites using proton-induced X-ray emission

This work was designed to examine the elemental constituents and physiochemical parameters of dumpsites in four local government areas in Ondo State. Elemental composition and physiochemical parameters such as pH, electrical conductivity, temperature, chloride and nitrate were analyzed in soil samples. The data were analyzed using the windows version 24.0 of the IBM Statistical Package for Social Sciences. Odigbo reported the highest mean concentrations in Al, Zn and Co. The highest mean concentrations of metals were Si, K, Cr, S and Y in Okitipupa. Although at Irele P, Fe, Rb, Sr, Bi and Au had the maximum mean concentration, in Control Site, Cl and Mn had an exponential increase in value. The highest value was observed in Ilaje for V, Cu, As, Zr, Sn, Pb. There was significant spatial variation (p < 0.05) in all metals except Sr, Bi and Y, which did not reveal any significant difference in mean concentration. The soil sample values at other sites were greater than the values collected at the control site. This study found that some of the obtained elemental concentrations were higher than the regulatory limits of the Soil-7 International Atomic Energy Agency and the World Health Organization. The study also revealed that continuous deposition of the elements in these dumpsites could lead to a threat to human health and to the environment.

Characterization and Hazard Identification of Respirable Cement and Concrete Dust from Construction Activities

Construction is an important segment of the economy that employs millions of people. Construction dust is an occupational health hazard to millions of construction workers worldwide. The hazards associated with respirable dust depend upon its particulate size distribution and chemical composition, as these determine the deposition pattern in the respiratory tract and reactivity, respectively. This study presents characterization of the size and composition of the dust from two key construction materials-cast cement and poured concrete. The dust was generated by cutting the cured cement and concrete blocks using an 18" hand-held circular saw as used in highway and building construction. Transmission electron microscopy, scanning electron microscopy, dynamic light scattering, and laser diffraction were performed for the size analysis of the particles. Energy dispersive spectroscopy and X-ray photoelectron spectroscopy were used for chemical analysis. X-ray diffraction was used for phase identification. Electron diffraction patterns were obtained to assess the crystallinity of individual particles. They confirm the crystallinity of particles of different size and shapes. With a particle size range between 0.5 μm and 10 μm, greater than 90% of particles fell below 2.5 μm, presenting a respirable health concern. Crystalline compounds including the metals Al, Ca, Fe, Mg, Na, and K were detected. The concrete particles were most enriched in crystalline silica with a concentration of more than 30% by weight. The presence of metals and high crystalline silica content pose a serious health concern to construction workers.

Trading One Risk for Another: Consequences of the Unauthenticated Treatment and Prevention of Silicosis in Ontario Miners in the McIntyre Powder Aluminum Inhalation Program

From 1943 to 1979, miners and factory workers in more than two hundred work sites globally were subjected to mandatory medical treatments by their employers as an unproven, and ultimately ineffective, treatment to prevent the lung disease silicosis. The treatments involved inhaling finely ground aluminum dust known as McIntyre Powder, blown into miners’ change rooms each shift using compressed air systems. Tens of thousands of industrial laborers were exposed to McIntyre Powder, yet their story is scarcely known, and the possible health impacts of their aluminum treatments were rarely studied. This paper integrates the history of the aluminum prophylaxis program and its control by the northern Ontario mining industry with the lived experience of one of the affected miners, whose daughter created a voluntary registry which documents health issues in exposed miners, and stimulated research that found a link to her father’s Parkinson disease.

The association between urinary aluminum and lung function among an urban adult population: A repeated-measure longitudinal study

OBJECTIVES

To investigate the cross-sectional and longitudinal associations between aluminum exposure and lung function and the risk of chronic obstructive pulmonary disease (COPD).

METHODS

The repeated-measure study was developed with 3917 adults from the Wuhan-Zhuhai cohort and they were followed-up after 3 years and 6 years. Urinary aluminum and lung function were measured at each period. Linear mixed models were used to estimate the exposure-response relationship between urinary aluminum and lung function. COX regression models were used to evaluate the association of urinary aluminum with the risk of COPD.

RESULTS

A total of 6996 observations including 2251 (32.2%) males with a mean age of 54.8 years were included. In the cross-sectional analyses, each 1-unit increase in log-transformed urinary aluminum was associated with a -33.34 mL (95% confidence interval (CI) -45.71 to -20.96) change in forced vital capacity (FVC) and a -17.89 mL (-27.80 to -7.97) change in forced expiratory volume in 1 s (FEV1). The follow-up analyses detected a negative association between urinary aluminum and the annual change of FVC (-6.73 mL/year, 95% CI -10.92 to -2.54), while the association of annual decline of FEV1 with urinary aluminum was statistically insignificant (-2.26 mL/year, -5.76 to 1.23). In the adjusted COX regression model, each 1-unit increase in log-transformed urinary aluminum was associated with a 29% increase in the incident risk of COPD (hazard ratio 1.29, 95% CI 1.04-1.62).

INCLUSION

Increased urinary aluminum was associated with lung function reduction and the increased risk of COPD in a general urban population.

The REACH registration process: A case study of metallic aluminium, aluminium oxide and aluminium hydroxide

The European Union's REACH Regulation requires determination of potential health and environmental effects of chemicals in commerce. The present case study examines the application of REACH guidance for health hazard assessments of three high production volume (HPV) aluminium (Al) substances: metallic aluminium, aluminium oxide, and aluminium hydroxide. Among the potential adverse health consequences of aluminium exposure, neurotoxicity is one of the most sensitive targets of Al toxicity and the most critical endpoint. This case study illustrates integration of data from multiple lines of evidence into REACH weight of evidence evaluations. This case study then explains how those results support regulatory decisions on classification and labelling. Challenges in the REACH appraisal of Al compounds include speciation, solubility and bioavailability, application of assessment factors, read-across rationale and differences with existing regulatory standards. Lessons learned from the present case study relate to identification and evaluation of toxicologic and epidemiologic data; assessing data relevance and reliability; development of derived no-effect levels (DNELs); addressing data gaps and preparation of chemical safety reports.

Neurodegenerative diseases among miners in Ontario, Canada, using a linked cohort

OBJECTIVES

We examined employment in mining occupations and industries and its association with neurological disease incidence in a linkage cohort from Ontario, Canada. Outcomes included Alzheimer's disease (alone and with other dementias), Parkinson's disease, parkinsonism, motor neuron disease and amyotrophic lateral sclerosis (ALS).

METHODS

The Occupational Disease Surveillance System cohort was created by linking workers' compensation data and healthcare usage records. This analysis included over 1.1 million male workers, followed between 1999 and 2016. Neurological diseases were ascertained using physician billing and hospital discharge records. Adjusted Poisson regression models were used to estimate incidence rate ratios (RR) comparing mining to non-mining workers overall and by ore (industry) and occupation group.

RESULTS

Suggested elevations in incidence rates were observed for ALS among workers of metal mines (RR 2.21, 95% CI 1.04 to 4.69) and for motor neuron disease among those employed in mining occupations within metal mining industries (RR 1.96, 95% CI 1.01 to 3.79), though these were based on relatively few cases. In miscellaneous metal mines, workers who held mining occupations had an elevated rate of Alzheimer's disease (RR 1.27, 95% CI 0.92 to 1.77). Parkinson's disease rate was elevated among workers with rock and soil drilling occupations (RR 1.60, 95% CI 1.04 to 2.45).

CONCLUSIONS

Mining hazards may be associated with elevated rates of neurodegenerative diseases among workers in mining occupations and industries. More work is needed to better understand mining exposures and their associations with neurodegenerative diseases.

Relationship between occupational aluminium exposure and histone lysine modification through methylation

BACKGROUND

Aluminium is an environmental neurotoxin to which human beings are extensively exposed. However, the molecular mechanism of aluminium toxicity remains unclear.

METHODS

The changes in cognitive function of aluminum exposed workers under long-term occupational exposure were evaluated, and the relationship between cognitive changes, plasma memory related BDNF and EGR1 protein expression, and variations of epigenetic markers H3K4me3, H3K9me2, H3K27me3 expression levels in blood was explored.

RESULTS

MMSE, DSFT, DST scores in cognitive function and the levels of plasma BDNF and EGR1 protein expression decreased with the increase of blood aluminum level. H3K4me3, H3K9me2, H3K27me3 expression levels in peripheral blood lymphocytes of aluminum exposed workers were statistically different (all P<0.05). H3K4me3, H3K9me2 and H3K27me3 expression levels in lymphocytes were correlated with blood aluminum level. BDNF, EGR1 protein level and H3K4me3, H3K9me2, H3K27me3 expression levels have different degrees of correlation. There was a linear regression relationship between plasma BDNF, H3K4me3 and H3K9me2. H3K9me2 had a greater effect on BDNF than H3K4me3. There is a linear regression relationship between EGR1, H3K4me3 and H3K27me3, and the influence of H3K4me3 on EGR1 is greater than that of H3K27me3 on EGR1.

CONCLUSION

Alummnum may regulate the expression of BDNF and EGR1 by regulating H3K4me3, H3K27me3 and H3K9me2, and affect the cognitive function of workers by affecting the expression of BDNF and EGR1.

Elemental analysis in living human subjects using biomedical devices

Today, patients undergoing dialysis are at low risk for aluminum-induced dementia. Workers are unlikely to experience cadmium-induced emphysema and the public's exposure to lead is an order of magnitude lower than in 1970. The research field of in vivo elemental analysis has played a role in these occupational and environmental health improvements by allowing the effects of people's chronic exposure to elements to be studied using non-invasive, painless, and relatively low-cost technology. From the early 1960s to the present day, researchers have developed radiation-based systems to measure the elemental content of organs at risk or storage organs. This reduces the need for (sometimes painful) biopsy and the risk of infection. Research and development has been undertaken on forty-nine in vivo measurement system designs. Twenty-nine different in vivo elemental analysis systems, measuring 22 different elements, have been successfully taken from design and testing through to human measurement. The majority of these systems employ either neutron activation analysis or x-ray fluorescence analysis as the basis of the measurement. In this review, we discuss eight of the successful systems, explaining the rationale behind their development, the methodology, the health data that has resulted from application of these tools, and provide our opinion on potential future technical developments of these systems. We close by discussing four technologies that may lead to new directions and advances in the whole field.

A qualitative descriptive study of underground workers who received aluminum dust treatment and its organizational level impact

From 1943 to 1980, some underground gold and uranium workers in Ontario, Canada were required to inhale aluminum dust for silicosis prevention. Workers were exposed to the dust for up to 30 min daily. This study explored the perceived organizational impact on workers exposed to the aluminum dust treatment in Northeastern Ontario. This qualitative descriptive study included 16 respondents who participated in individual semi-structured interviews. All respondents were Northeastern Ontario workers who were exposed to aluminum dust treatment for at least 1 year. Interviews were transcribed verbatim and analyzed thematically. Themes that emerged were: 1) confidence and trust in companies, 2) lack of participants' and heath care providers' knowledge, and 3) need for compensation and formal apology. Workers' perceived that their long term health was impacted by exposure. The results will be used to help workers, companies, and unions address workplace exposures. The latest information about McIntyre powder will enhance the knowledge about the impact of the exposure.

Physical and chemical characterization of McIntyre Powder: An aluminum dust inhaled by miners to combat silicosis

McIntyre Powder (MP) is a finely ground aluminum powder that was used between 1943 and 1979 as a prophylaxis for silicosis. Silicosis is a chronic lung disease caused by the inhalation of crystalline silica dust and was prevalent in the Canadian mining industry during this time period. The McIntyre Research Foundation developed, patented, and produced the MP and distributed it to licensees in Canada, the United States, Mexico, Chile, Belgian Congo, and Western Australia. In the province of Ontario, Canada it is estimated that at least 27,500 miners between 1943 and 1979 were exposed to MP. The present study was undertaken to examine the chemical and physical characteristics of two variations of MP (light grey and black). Chemical analyses (using X-ray Fluorescence and Inductively Coupled Plasma approaches) indicate that the black MP contains significantly higher concentrations of aluminum and metal impurities than the light grey MP (p < 0.001). X-ray diffractometry shows that while aluminum hydroxide dominates the aluminum speciation in both variations, the higher total aluminum content in the black MP is attributable to a greater proportion of elemental aluminum. Physical characterization (using electron microscopy, light microscopy, and dynamic light scattering) indicates that the light grey MP consists of particles ranging from 5 nm to 5 µm in diameter. Atomic Force Microscopy shows that the light grey MP particles in the nanoparticle range (<100 nm) have a mode between 5 and 10 nm. Consequently, it is possible that inhaled smaller MP nanoparticles may be transported via blood and lymph fluid circulation to many different organs including the brain. It is also possible for inhaled larger MP particles to deposit onto lung tissue and for potential health effects to arise from inflammatory responses through immune activation. This MP characterization will provide crucial data to help inform future toxicological, epidemiological, and biological studies of any long-term effects related to the inhalation of aluminum dust and nanomaterials.

Silica-associated lung disease: An old-world exposure in modern industries

Despite silica dust exposure being one of the earliest recognized causes of lung disease, Australia, USA, Israel, Turkey and other countries around the world have recently experienced significant outbreaks of silicosis. These outbreaks have occurred in modern industries such as denim jean production, domestic benchtop fabrication and jewellery polishing, where silica has been introduced without recognition and control of the hazard. Much of our understanding of silica-related lung disease is derived from traditional occupations such as mining, whereby workers may develop slowly progressive chronic silicosis. However, workers in modern industries are developing acute and accelerated silicosis over a short period of time, due to high-intensity silica concentrations, oxidative stress from freshly fractured silica and a rapid pro-inflammatory and pro-fibrotic response. Appropriate methods of screening and diagnosis remain unclear in these workers, and a significant proportion may go on to develop respiratory failure and death. There are no current effective treatments for silicosis. For those with near fatal respiratory failure, lung transplantation remains the only option. Strategies to reduce high-intensity silica dust exposure, enforced screening programmes and the identification of new treatments are urgently required.

Associations of multiple plasma metals with the risk of ischemic stroke: A case-control study

BACKGROUND

Ischemic stroke (IS) is a major cause of morbidity and mortality globally. Environmental exposure to metals may be linked to the risk of IS, but the association remains uncertain in Chinese populations.

OBJECTIVES

The present study aimed to examine the associations between the concentrations of 11 metals (aluminum, arsenic, cadmium, cobalt, copper, iron, manganese, molybdenum, selenium, thallium, and zinc) in plasma and the risk of IS in a Chinese population.

METHODS

A total of 1277 pairs of newly diagnosed IS patients and controls matched on age (±3 years) and sex were recruited in our study. Plasma metal concentrations were measured using inductively coupled plasma mass spectrometry. Multivariable conditional logistic regression models were conducted to investigate the impacts of single and multiple metals, respectively.

RESULTS

In the single-metal model, exposure to seven metals (aluminum, arsenic, cadmium, cobalt, iron, manganese and selenium) was individually associated with the risk of IS based on the trend test. Further stepwise regression analyses with the multiple-metal model revealed increasing trends in the risk of IS associated with aluminum, arsenic, and cadmium quartiles and decreasing trends with iron and selenium quartiles (p-trend < 0.01). Compared to the lowest quartiles, the odds ratios (95% confidence intervals) for the highest quartiles of these five metals were 4.23 (2.63, 6.79), 1.88 (1.25, 2.81), 5.02 (3.30, 7.63), 0.59 (0.40, 0.89), and 0.10 (0.06, 0.17), respectively.

CONCLUSIONS

Our study suggested that higher plasma concentrations of aluminum, arsenic, and cadmium, and lower concentrations of iron and selenium may increase the risk of IS. Further prospective studies in larger populations are warranted to confirm our findings.

Metal emissions from e-cigarettes: a risk assessment analysis of a recently-published study

Introduction: A recent study reported levels of metal emissions in e-cigarette (EC) aerosol. Herein we present a risk assessment analysis of the published findings using total daily exposure limits. Methods: Median and 75th percentile metal concentrations in EC aerosols were used to determine the level of daily liquid consumption (g/d) that would exceed the permissible daily exposures (PDEs) defined for inhalation medications (cadmium, chromium, copper, nickel, lead, antimony and tin). For metals not having PDEs, minimal risk levels (manganese) or risk exposure levels (aluminum, iron and zinc) were converted into total daily exposure using an inhalation volume of 20 m³ (for 24 h) and 6.7 m³ (for 8 h) respectively. Results: The lowest amount of liquid consumption exceeding safety limits was found for nickel (73 g/day for median and 17 g/day for 75th percentile levels). The consumption corresponding to the 75th percentile could be associated with realistic use, although this would represent an extreme rather than average consumption. For chromium, the respective levels were 358 and 68 g/day and for lead 338 and 135 g/day. For all other metals, liquid consumption would need to be orders of magnitude higher, reaching to 1.5 million grams for aluminum. Conclusion: EC emissions contain trace levels of metals. For almost all metals, unrealistically high levels of liquid need to be consumed in order for total daily exposure to exceed established limits.

Plasma Metal Concentrations and Incident Coronary Heart Disease in Chinese Adults: The Dongfeng-Tongji Cohort

BACKGROUND

Circulating metals from both the natural environment and pollution have been linked to cardiovascular disease. However, few prospective studies have investigated the associations between exposure to multiple metals and incident coronary heart disease (CHD).

OBJECTIVES

We conducted a nested case-control study in the prospective Dongfeng-Tongji cohort, to investigate the prospective association between plasma metal concentrations and incident CHD.

METHODS

A total of 1,621 incident CHD cases and 1,621 controls free of major cardiovascular disease at baseline and follow-up visits were matched on age (±5 years) and sex. We measured baseline fasting plasma concentrations of 23 metals and used conditional logistic regression models to estimate odds ratios (ORs) of CHD for metal concentrations categorized according to quartiles in controls.

RESULTS

Five metals (titanium, arsenic, selenium, aluminum, and barium) were significantly associated with CHD based on trend tests from single-metal multivariable models adjusted for established cardiovascular risk factors. When all five were included in the same model, adjusted ORs for barium and aluminum were close to the null, whereas associations with titanium, arsenic, and selenium were similar to estimates from single-metal models, and ORs comparing extreme quartiles were 1.32 (95% CI: 1.03, 1.69; p-trend=0.04), 1.78 (95% CI: 1.29, 2.46; p-trend=0.001), and 0.67 (95% CI: 0.52, 0.85; p-trend=0.001), respectively.

CONCLUSIONS

Our study suggested that incident CHD was positively associated with plasma levels of titanium and arsenic, and inversely associated with selenium. Additional research is needed to confirm these findings in other populations. https://doi.org/10.1289/EHP1521.

Trends in exposure to respirable crystalline silica (1986-2014) in Australian mining

BACKGROUND

Respirable crystalline silica (RCS) has been associated with severe health risks. Exposures in Western Australia (WA) have been typically high in hard-rock mining and have reduced substantially since the mid-1900s. We described trends in RCS exposure in WA miners over the past 30 years.

METHODS

A total of 79 445 reported personal RCS exposure measurements, covering the years 1986-2014, were examined. Mixed-effects models were applied to estimate RCS exposure levels, including spline terms to estimate a time trend.

RESULTS

An overall downward trend of about -8% per year was observed for RCS exposures in WA mining. Highest RCS exposure levels were modeled for base metal mining and exploration settings. Drilling occupations were among the highest exposed jobs.

CONCLUSION

RCS exposure levels have fallen considerably in the last three decades. However, there are still mining occupations that may need further attention to avoid adverse health effects in these workers.

Environmental risk factors for dementia: a systematic review

BACKGROUND

Dementia risk reduction is a major and growing public health priority. While certain modifiable risk factors for dementia have been identified, there remains a substantial proportion of unexplained risk. There is evidence that environmental risk factors may explain some of this risk. Thus, we present the first comprehensive systematic review of environmental risk factors for dementia.

METHODS

We searched the PubMed and Web of Science databases from their inception to January 2016, bibliographies of review articles, and articles related to publically available environmental data. Articles were included if they examined the association between an environmental risk factor and dementia. Studies with another outcome (for example, cognition), a physiological measure of the exposure, case studies, animal studies, and studies of nutrition were excluded. Data were extracted from individual studies which were, in turn, appraised for methodological quality. The strength and consistency of the overall evidence for each risk factor identified was assessed.

RESULTS

We screened 4784 studies and included 60 in the review. Risk factors were considered in six categories: air quality, toxic heavy metals, other metals, other trace elements, occupational-related exposures, and miscellaneous environmental factors. Few studies took a life course approach. There is at least moderate evidence implicating the following risk factors: air pollution; aluminium; silicon; selenium; pesticides; vitamin D deficiency; and electric and magnetic fields.

CONCLUSIONS

Studies varied widely in size and quality and therefore we must be circumspect in our conclusions. Nevertheless, this extensive review suggests that future research could focus on a short list of environmental risk factors for dementia. Furthermore, further robust, longitudinal studies with repeated measures of environmental exposures are required to confirm these associations.

Low levels of aluminum can lead to behavioral and morphological changes associated with Alzheimer's disease and age-related neurodegeneration

Aluminum (Al) is a very common component of the earth's mineral composition. It is not essential element for life and is a constituent of rather inert minerals. Therefore, it has often been regarded as not presenting a significant health hazard. As a result, aluminum-containing agents been used in the preparation of many foodstuffs processing steps and also in elimination of particulate organic matter from water. More recently, the reduced pH of bodies of water resulting from acid rain has led to mobilization of aluminum-containing minerals into a more soluble form, and these have thus entered residential drinking water resources. By this means, the body burden of aluminum in humans has increased. Epidemiological and experimental findings indicate that aluminum is not as harmless as was previously thought, and that aluminum may contribute to the inception and advancement of Alzheimer's disease. Epidemiological data is reinforced by indications that aluminum exposure can result in excess inflammatory activity within the brain. Activation of the immune system not initiated by an infectious agent, typifies the aging brain and is even more augmented in several neurodegenerative diseases. The origin of most age-related neurological disorders is generally not known but as they are largely not of genetic derivation, their development is likely triggered by unknown environmental factors. There is a growing and consistent body of evidence that points to aluminum as being one such significant influence. Evidence is presented that reinforces the likelihood that aluminum is a factor speeding the rate of brain aging. Such acceleration would inevitably enlarge the incidence of age-related neurological diseases.

Dietary Patterns and Risk of Dementia: a Systematic Review and Meta-Analysis of Cohort Studies

Dietary patterns and some dietary components have been linked with dementia. We therefore performed a meta-analysis of available studies to determine whether there is an association between diet and risk of dementia. We included eligible articles and estimated risk ratio (RR) with 95 % confidence intervals (95 % CIs). Finally, there were 43 trials that met the inclusion standard. Some food intake was related with decrease of dementia, such as unsaturated fatty acids (RR: 0.84, 95 % CI: [0.74-0.95], P = 0.006), antioxidants (RR: 0.87, 95 % CI: [0.77-0.98], P = 0.026), vitamin B (RR: 0.72, 95 % CI: [0.54-0.96], P = 0.026), and the Mediterranean diet (MeDi) (RR: 0.69, 95 % CI: [0.57-0.84], P < 0.001). Some material intakes were related with increase of dementia, such as aluminum (RR: 2.24, 95 % CI: [1.49-3.37], P < 0.001), smoking (RR: 1.43, 95 % CI: [1.15-1.77], P = 0.001), and low levels of vitamin D (RR: 1.52, 95 % CI: [1.17-1.98], P = 0.002). The effect of some materials needs further investigation, such as fish (RR: 0.79, 95 % CI: [0.59-1.06], P = 0.113), vegetables and fruits (RR: 0.46, 95 % CI: [0.16-1.32], P = 0.149), and alcohol (RR: 0.74, 95 % CI: [0.55- 1.01], P = 0.056). Thus, the MeDi and higher consumption of unsaturated fatty acids, antioxidants, and B vitamins decrease the risk of dementia while smoking and higher consumption of aluminum increase the risk of dementia. Low levels of vitamin D were associated with cognitive decline. The effect of fish, vegetables, fruits, and alcohol needs further investigation. The findings will be of great significance to guide people to prevent dementia.