Investigating the potential for interaction between the components of PM(10)

Interactive effects of meteorological factors and air pollutants on hand, foot, and mouth disease in Chengdu, China: a time-series study

OBJECTIVES

Hand, foot, and mouth disease (HFMD) is a viral infectious disease that poses a substantial threat in the Asia-Pacific region. It is widely reported that meteorological factors are associated with HFMD. However, the relationships between air pollutants and HFMD are still controversial. In addition, the interactive effects between meteorological factors and air pollutants on HFMD remain unknown. To fill this research gap, we conducted a time-series study.

DESIGN

A time-series study.

SETTING AND PARTICIPANTS

Daily cases of HFMD as well as meteorological and air pollution data were collected in Chengdu from 2011 to 2017. A total of 184 610 HFMD cases under the age of 15 were included in our study.

OUTCOME MEASURES

Distributed lag nonlinear models were used to investigate the relationships between HFMD and environmental factors, including mean temperature, relative humidity, SO₂, NO₂, and PM₁₀. Then, the relative excess risk due to interaction (RERI) and the proportion attributable to interaction were calculated to quantitatively evaluate the interactions between meteorological factors and air pollutants on HFMD. Bivariate response surface models were used to visually display the interactive effects.

RESULTS

The cumulative exposure-response curves of SO₂ and NO₂ were inverted 'V'-shaped and 'M'-shaped, respectively, and the risk of HFMD gradually decreased with increasing PM₁₀ concentrations. We found that there were synergistic interactions between mean temperature and SO₂, relative humidity and SO₂, as well as relative humidity and PM₁₀ on HFMD, with individual RERIs of 0.334 (95% CI 0.119 to 0.548), 0.428 (95% CI 0.214 to 0.642) and 0.501 (95% CI 0.262 to 0.741), respectively, indicating that the effects of SO₂ and PM₁₀ on HFMD were stronger under high temperature (>17.3°C) or high humidity (>80.0%) conditions.

CONCLUSIONS

There were interactive effects between meteorological factors and air pollutants on HFMD. Our findings could provide guidance for targeted and timely preventive and control measures for HFMD.

Variations in Reactive Oxygen Species Generation by Urban Airborne Particulate Matter in Lung Epithelial Cells-Impact of Inorganic Fraction

Air pollution is associated with numerous negative effects on human health. The toxicity of organic components of air pollution is well-recognized, while the impact of their inorganic counterparts in the overall toxicity is still a matter of various discussions. The influence of airborne particulate matter (PM) and their inorganic components on biological function of human alveolar-like epithelial cells (A549) was investigated in vitro. A novel treatment protocol based on covering culture plates with PM allowed increasing the studied pollutant concentrations and prolonging their incubation time without cell exposure on physical suffocation and mechanical disturbance. PM decreased the viability of A549 cells and disrupted their mitochondrial membrane potential and calcium homeostasis. For the first time, the difference in the reactive oxygen species (ROS) profiles generated by organic and inorganic counterparts of PM was shown. Singlet oxygen generation was observed only after treatment of cells with inorganic fraction of PM, while hydrogen peroxide, hydroxyl radical, and superoxide anion radical were induced after exposure of A549 cells to both PM and their inorganic fraction.

Influence of coarse particulate matter on chickenpox in Jiading District, Shanghai, 2009-2018: A distributed lag non-linear time series analysis

Although the link between ambient air pollution and some infectious diseases has been studied, few studies have explored so far, the relationship between chickenpox and particulate matter. Daily chickenpox counts in Jiading District, Shanghai, were collected from 2009 to 2018. Time series analysis was conducted to describe the trends of the daily number of chickenpox cases and the concentration of particulate matter 10 μm or less (PM10). The distributed lag non-linear model (DLNM) was developed to assess the lag and non-linear relationship between the number of chickenpox cases and PM10 concentration adjusting for meteorological factors and other pollutants. Spatiotemporal scanning was used to detect the clustering of chickenpox cases. There was a concomitant relationship between the number of chickenpox cases and PM10 concentration, especially in the period of high PM10 concentration. DLNM results showed a nonlinear relationship between the number of chickenpox cases and PM10 concentration with the maximum effect of PM10 being lagged for 13-14 days, which was consistent with the average incubation period of chickenpox. PM10 was significantly associated with the daily number of chickenpox cases when above 300 μg/m³. The risk of chickenpox increased with increasing PM10 concentration and the association was strongest at the lag of 14 day (RR = 1.13, 95% CI: 1.04-1.23) for PM10 concentration of 500 μg/m³ versus 50 μg/m³. The study provides evidence that high PM10 concentration increases the risk of chickenpox spreading.

Protective equipment and health education program could benefit students from dust pollution

In recent years, children living in the downstream of the Choshui River in Taiwan have been exposed to violent dust episodes. For the sake of the health of these children, we aimed to investigate the effectiveness of protective equipment (sand-proof plastic cover and air purifier) installed outside/inside the classrooms on students' pulmonary function and evaluate the health education program for preventing the adverse consequences of exposure to river-dust episodes. Public elementary school students in Yunlin County, which was severely affected by river-dust, were selected as the participants. Study 1 consisted of three-wave follow-up data (801 person-times) in high-/low-dust exposure regions to examine pulmonary function. Study 2 used 147 and 73 students in the high-/low-dust exposure regions, respectively, to establish our health education intervention. Paired t tests, repeated measures ANOVA, and generalized estimating equation were used to analyze the short- and long-term effects. The results showed that the students' pulmonary function in schools that installed protective equipment was improved. The health education (such as the usage of correct masks and our designed PM_2.5 full-cover sand-proof clothing) improved the students' cognition and behaviors related to river-dust episodes and yielded both short- and long-term effects. Therefore, we suggest more schools with high-dust exposure to adopt protective equipment and health education program. Our designed PM_2.5 full-cover sand-proof clothing can prevent from not only haze but also droplet transmission by infectious diseases such as COVID-19.

Blood pressure in indoor and outdoor workers

INTRODUCTION

The aim of our study is to evaluate the changes in systolic and diastolic blood pressure in two occupational categories: outdoor workers (traffic policemen and environment technicians) and indoor workers.

MATERIALS AND METHODS

The study was conducted comparing the results obtained from three samples of male workers: 175 outdoor traffic policemen, 175 outdoor environment technicians and 175 indoor workers. The outdoor and indoor groups were made comparable by age, length of service, body mass index, alcohol consumption, smoking status.

RESULTS

The mean values of systolic and diastolic blood pressure were found higher in traffic policemen and technicians than in indoor workers, as well as higher values of systolic blood pressure in traffic policemen than in technicians.

CONCLUSIONS

The results suggest that outdoor working affects the blood pressure, contributing to an increased cardiovascular risk.

Effects of permissible maximum-contamination levels of VOC mixture in water on total DNA, antioxidant gene expression, and sequences of ribosomal DNA of Drosophila melanogaster

In this study, we aimed to investigate the mutagenic and carcinogenic potential of a volatile organic compound (VOC) mixture with references to the response of D.melanogaster using selected antioxidant gene expressions, RAPD assay and base-pair change of ribosomal 18S, and the internal transcribed spacer, ITS2 rDNA gene sequences. For this purpose, Drosophila melanogaster Oregon R, reared under controlled conditions on artificial diets, were treated with the mixture of thirteen VOCs, which are commonly found in water in concentrations of 10, 20, 50, and 75 ppb for 1 and 5 days. In the random amplified polymorphic DNA (RAPD) assay, band changes were clearly detected, especially at the 50 and 75 ppb exposure levels, for both treatment periods, and the band profiles exhibited clear differences between the treated and untreated flies with changes in band intensity and the loss/appearance of bands. Quantitative real-time PCR (qRT-PCR) analysis of Mn-superoxide dismutase (Mn-SOD), catalase (CAT) and glutathione-synthetase (GS) expressions demonstrated that these markers responded significantly to VOC-induced oxidative stress. Whilst CAT gene expressions increased linearly with increasing concentrations of VOCs and treatment times, the 50- and 75-ppb treatments caused decreases in GS expressions compared to the control at 5 days. Treatment with VOCs at both exposure times, especially in high doses, caused gene mutation of the 18S and the ITS2 ribosomal DNA. According to this research, we thought that the permissible maximum-contamination level of VOCs can cause genotoxic effect especially when mixed.

Effects of a mixture of volatile organic compounds on total DNA and gene expression of heat shock proteins in Drosophila melanogaster

The genotoxic effects of a mixture of 13 volatile organic compounds (VOCs) on total DNA profiles and the expression of heat shock proteins (HSPs) HSP26, HSP60, HSP70, and HSP83 in fruit fly tissues were examined. Drosophila melanogaster Oregon R(+), reared under controlled conditions on artificial diets, was treated with 13 VOCs commonly found in water at concentrations of 10, 20, 50, and 75 ppb for 1 and 5 days. Band changes were clearly detected in random amplified polymorphic DNA assay, especially at the 50- and 75-ppb exposure levels, for both treatment periods. In addition, there were clear differences in the band profiles of the treated and untreated flies with changes in the band intensity and the loss/appearance of bands. Although the genomic template stability (GTS) exhibited irregular changes at the first day, significant decreases in GTS were observed after 5 days of VOC application. The lowest GTS value (27.77 ± 1.96 %) was detected at the 75-ppb level after 5 days of the treatment. Quantitative real-time polymerase chain reaction analysis showed a significant increase in the relative expression of HSP26 and HSP60 after 1 and 5 days of the treatment, respectively. The expression of HSP70 increased significantly at all treatment concentrations and times. However, the greatest increase in expression level of HSP70 (4.2-fold) occurred at 20 ppb after 5 days of the treatment. HSP83 was the least affected by exposure to the VOCs. We conclude that trace levels of a mixture of VOCs can exert genotoxic effects on both total DNA and HSP levels in Drosophila.

Pulmonary oxidative stress, inflammation and cancer: respirable particulate matter, fibrous dusts and ozone as major causes of lung carcinogenesis through reactive oxygen species mechanisms

Reactive oxygen or nitrogen species (ROS, RNS) and oxidative stress in the respiratory system increase the production of mediators of pulmonary inflammation and initiate or promote mechanisms of carcinogenesis. The lungs are exposed daily to oxidants generated either endogenously or exogenously (air pollutants, cigarette smoke, etc.). Cells in aerobic organisms are protected against oxidative damage by enzymatic and non-enzymatic antioxidant systems. Recent epidemiologic investigations have shown associations between increased incidence of respiratory diseases and lung cancer from exposure to low levels of various forms of respirable fibers and particulate matter (PM), at occupational or urban air polluting environments. Lung cancer increases substantially for tobacco smokers due to the synergistic effects in the generation of ROS, leading to oxidative stress and inflammation with high DNA damage potential. Physical and chemical characteristics of particles (size, transition metal content, speciation, stable free radicals, etc.) play an important role in oxidative stress. In turn, oxidative stress initiates the synthesis of mediators of pulmonary inflammation in lung epithelial cells and initiation of carcinogenic mechanisms. Inhalable quartz, metal powders, mineral asbestos fibers, ozone, soot from gasoline and diesel engines, tobacco smoke and PM from ambient air pollution (PM₁₀ and PM₂.₅) are involved in various oxidative stress mechanisms. Pulmonary cancer initiation and promotion has been linked to a series of biochemical pathways of oxidative stress, DNA oxidative damage, macrophage stimulation, telomere shortening, modulation of gene expression and activation of transcription factors with important role in carcinogenesis. In this review we are presenting the role of ROS and oxidative stress in the production of mediators of pulmonary inflammation and mechanisms of carcinogenesis.

Reduced alveolar macrophage migration induced by acute ambient particle (PM10) exposure

Increased levels of particulate air pollution (PM10) have been implicated as a causal agent in pulmonary disease exacerbation and increased deaths from respiratory and cardiovascular disorders. The exact mechanism by which PM10 drives toxicity in the lung is still unknown, but studies have focused on inhibition of macrophage function and impaired alveolar clearance mechanisms. To assess the effects of PM10 on pulmonary macrophage clearance mechanisms ex vivo, Wistar rats were instilled with 125 or 250 microg of PM10 collected from the North Kensington, London. Control rats were instilled with sterile saline. The rats were sacrificed after 18 h and a bronchoalveolar lavage (BAL) was performed. Macrophages isolated from the BAL fluid were assessed for ability to migrate towards a positive chemoattractant (ZAS) ex vivo and to perform phagocytosis. Macrophages isolated from the PM10-exposed rats showed inhibition of potential to migrate. Macrophage phagocytic ability ex vivo was also significantly reduced by the presence of PM10 inside the cells. This study indicates that acute PM10 exposure diminishes macrophage motility and phagocytosis in a manner that could prove deleterious to particle clearance from the alveolar region of the lung. Decreased particle clearance promotes inflammation, and hence, warrants further investigation in relation to the effects of chronic PM10 exposure on macrophage clearance mechanisms and establishing the mechanisms behind decreased macrophage migration.

The effect of refurbishing a UK steel plant on PM10 metal composition and ability to induce inflammation

Background

In the year 2000 Corus closed its steel plant operations in Redcar, NE of England temporarily for refurbishment of its blast furnace. This study investigates the impact of the closure on the chemical composition and biological activity of PM₁₀ collected in the vicinity of the steel plant.

Methods

The metal content of PM₁₀ samples collected before during and after the closure was measured by ICP-MS in order to ascertain whether there was any significant alteration in PM₁₀ composition during the steel plant closure. Biological activity was assessed by instillation of 24 hr PM₁₀ samples into male Wistar rats for 18 hr (n = 6). Inflammation was identified by the cellular and biochemical profile of the bronchoalveolar lavage fluid. Metal chelation of PM₁₀ samples was conducted using Chelex beads prior to treatment of macrophage cell line, J774, in vitro and assessment of pro-inflammatory cytokine expression.

Results

The total metal content of PM₁₀ collected before and during the closure period were similar, but on reopening of the steel plant there was a significant 3-fold increase (p < 0.05) compared with the closure and pre-closure samples. Wind direction prior to the closure was predominantly from the north, compared to south westerly during the closure and re-opened periods. Of metals analysed, iron was most abundant in the total and acid extract, while zinc was the most prevalent metal in the water-soluble fraction. Elevated markers of inflammation included a significant increase (p < 0.01) in neutrophil cell numbers in the bronchoalveolar lavage of rats instilled with PM₁₀ collected during the reopened period, as well as significant increases in albumin (p < 0.05). Extracts of PM₁₀ from the pre-closure and closure periods did not induce any significant alterations in inflammation or lung damage. The soluble and insoluble extractable PM₁₀ components washed from the reopened period both induced a significant increase in neutrophil cell number (p < 0.05) when compared to the control, and these increases when added together approximately equalled the inflammation induced by the whole sample. PM₁₀ from the re-opened period stimulated J774 macrophages to generate TNF-α protein and this was significantly prevented by chelating the metal content of the PM₁₀ prior to addition to the cells.

Conclusion

PM₁₀-induced inflammation in the rat lung was related to the concentration of metals in the PM₁₀ samples tested, and activity was found in both the soluble and insoluble fractions of the particulate pollutant.

Oxidative stress and calcium signaling in the adverse effects of environmental particles (PM10)

This review focuses on the potential role that oxidative stress plays in the adverse effects of PM(10). The central hypothesis is that the ability of PM(10) to cause oxidative stress underlies the association between increased exposure to PM(10) and both exacerbations of lung disease and lung cancer. Pulmonary inflammation may also underlie the cardiovascular effects seen following increased PM(10), although the mechanisms of the cardiovascular effects of PM(10) are not well understood. PM(10) is a complex mix of various particle types and several of the components of PM(10) are likely to be involved in the induction of oxidative stress. The most likely of these are transition metals, ultrafine particle surfaces, and organic compounds. In support of this hypothesis, oxidative stress arising from PM(10) has been shown to activate a number of redox-responsive signaling pathways in lung target cells. These pathways are involved in expression of genes that play a role in responses relevant to inflammation and pathological change, including MAPKs, NF-kappaB, AP-1, and histone acetylation. Oxidative stress from particles is also likely to play an important role in the carcinogenic effects associated with PM(10) and hydroxyl radicals from PM(10) cause DNA damage in vitro.