Long-term exposure to ambient air pollution and incidence of brain tumor: the European Study of Cohorts for Air Pollution Effects (ESCAPE)

Exploring potential causal links between air pollutants and congenital malformations: A two-sample Mendelian Randomization study

Observational studies have suggested an association between air pollutants and congenital malformations; however, conclusions are inconsistent and the causal associations have not been elucidated. In this study, based on publicly available genetic data, a two-sample Mendelian randomization (MR) was applied to explore the associations between particulate matter 2.5 (PM2.5), NOX, NO2 levels and 11 congenital malformations. Inverse variance weighted (IVW), MR-Egger and weighted median were used as analytical methods, with IVW being the main method. A series of sensitivity analyses were used to verify the robustness of the results. For significant associations, multivariable MR (MVMR) was utilized to explore possible mediating effects. The IVW results showed that PM2.5 was associated with congenital malformations of digestive system (OR = 7.72, 95 %CI = 2.33-25.54, P = 8.11E-4) and multiple systems (OR = 8.63, 95 %CI = 1.02-73.43, P = 0.048) risks; NOX was associated with circulatory system (OR = 4.65, 95 %CI = 1.15-18.86, P = 0.031) and cardiac septal defects (OR = 14.09, 95 %CI = 1.62-122.59, P = 0.017) risks; NO2 was correlated with digestive system (OR = 27.12, 95 %CI = 1.81-407.07, P = 0.017) and cardiac septal defects (OR = 22.57, 95 %CI = 2.50-203.45, P = 0.005) risks. Further MVMR analyses suggest that there may be interactions in the effects of these air pollutants on congenital malformations. In conclusion, this study demonstrated a causal association between air pollution and congenital malformations from a genetic perspective.

Integrated meta-analyses of genome-wide effects of PM2.5 in human cells identifies widespread dysregulation of genes and pathways associated with cancer progression and patient survival

Epidemiological studies have consistently shown a positive association between exposure to ambient PM2.5, a major component of air pollution, and various types of cancer. Previous biological research has primarily focused on the association between PM2.5 and lung cancer, with limited investigation into other cancer types. In this study, we conducted a meta-analysis on multiple PM2.5-treated normal human cell lines to identify potential molecular targets and pathways of PM2.5. Our analysis revealed 310 common differentially expressed genes (DEGs) that exhibited significant dysregulation upon exposure to PM2.5. These dysregulated genes covered a diverse range of functional categories, including oncogenes, tumor suppressor genes, and immune-related genes, which collectively contribute to PM2.5-induced carcinogenesis. Pathway enrichment analysis revealed the up-regulation of pathways associated with HIF-1, VEGF, and MAPK signalling, all of which have been implicated in various cancers. Induction in the levels of HIF pathway genes (HIF1⍺, HIF2⍺, VEGFA, BNIP3, EPO and PGK1) upon PM2.5 treatment was also confirmed by qRT-PCR. Furthermore, the construction of a protein-protein interaction (PPI) network unveiled hub genes, such as NQO1 and PDGFRB, that are known to be dysregulated and significantly correlated with overall survival in lung and breast cancer patients, suggesting their potential clinical significance. This study provides a deep insight into how PM2.5-mediated dysregulation of oncogenes or tumor suppressor genes across various human tissues may play an important role in PM2.5-induced carcinogenesis. Further exploration of these dysregulated molecular targets may enhance our understanding of the biological effects of PM2.5 and facilitate the development of preventive strategies and targeted therapies for PM2.5-associated cancers.

The respiratory health effects of acute in vivo diesel and biodiesel exhaust in a mouse model

BACKGROUND

Biodiesel, a renewable diesel fuel that can be created from almost any natural fat or oil, is promoted as a greener and healthier alternative to commercial mineral diesel without the supporting experimental data to back these claims. The aim of this research was to assess the health effects of acute exposure to two types of biodiesel exhaust, or mineral diesel exhaust or air as a control in mice. Male BALB/c mice were exposed for 2-hrs to diluted exhaust obtained from a diesel engine running on mineral diesel, Tallow biodiesel or Canola biodiesel. A room air exposure group was used as a control. Twenty-four hours after exposure, a variety of respiratory related end point measurements were assessed, including lung function, responsiveness to methacholine and airway and systemic immune responses.

RESULTS

Tallow biodiesel exhaust exposure resulted in the greatest number of significant effects compared to Air controls, including increased airway hyperresponsiveness (178.1 ± 31.3% increase from saline for Tallow biodiesel exhaust exposed mice compared to 155.8 ± 19.1 for Air control), increased airway inflammation (63463 ± 13497 cells/mL in the bronchoalveolar lavage of Tallow biodiesel exhaust exposed mice compared to 40561 ± 11800 for Air exposed controls) and indications of immune dysregulation. In contrast, exposure to Canola biodiesel exhaust resulted in fewer significant effects compared to Air controls with a slight increase in airway resistance at functional residual capacity and indications of immune dysregulation. Exposure to mineral diesel exhaust resulted in significant effects between that of the two biodiesels with increased airway hyperresponsiveness and indications of immune dysregulation.

CONCLUSION

These data show that a single, brief exposure to biodiesel exhaust can result in negative health impacts in a mouse model, and that the biological effects of exposure change depending on the feedstock used to make the biodiesel.

Impact of environmental pollutants on pediatric brain tumor incidence in New Jersey

OBJECTIVE

The relationship between environmental contaminants and brain tumor incidence in adults has been thoroughly explored but research into how these contaminants affect pediatric brain tumor (PBT) incidence has not been explored. Children, typically having more limited geographical movement and thus more consistent environmental contaminant exposure, might offer more reliable insights into which environmental contaminants affect the incidence of brain tumors. The present study is the first to focus on exploring whether a possible association exists between the incidence of PBTs and exposure to environmental pollutants in New Jersey (NJ).

METHODS

Linear regressions were run between PBT incidence and the concentration of air quality pollutants such as Ozone (O3), Particulate Matter 2.5 (PM2.5), Particulate Matter 10 (PM10), and Carbon Monoxide (CO). Similarly, linear regressions were run between PBT incidence and Elevated Blood Lead Levels (BLL).

RESULTS

The study observed a significant positive relationship between O3 and PBT incidence (β = 0.34, p = 0.028). However, the relationship between PBT incidence, and environmental pollutants such as CO (β = 0.0047, p = 0.098), PM2.5 (β = -0.2624, p = 0.74), and PM10 (β = -0.7353, p = 0.073) were found to be nonsignificant. For elevated BLL, nonsignificant relationships with PBT incidence were observed at 10-14 µg/dL (β = -39.38, p = 0.30), 15-19 µg/dL (β = -67.00, p = 0.21), and 20-44 µg/dL (β = -201.98, p = 0.12).

CONCLUSIONS

The results indicate a possible impact of O3 on the incidence of PBTs in NJ. In contrast to the significant links found in prior studies of adult brain tumors, the associations between PBT occurrence and particulate matter were not significant. These findings highlight the importance of further investigating how environmental factors, especially O3, relate to PBTs.

ROS-dependent degeneration of human neurons induced by environmentally relevant levels of micro- and nanoplastics of diverse shapes and forms

Our study explores the pressing issue of micro- and nanoplastics (MNPs) inhalation and their subsequent penetration into the brain, highlighting a significant environmental health concern. We demonstrate that MNPs can indeed penetrate murine brain, warranting further investigation into their neurotoxic effects in humans. We then proceed to test the impact of MNPs at environmentally relevant concentrations, with focusing on variations in size and shape. Our findings reveal that these MNPs induce oxidative stress, cytotoxicity, and neurodegeneration in human neurons, with cortical neurons being more susceptible than nociceptors. Furthermore, we examine the role of biofilms on MNPs, demonstrating that MNPs can serve as a vehicle for pathogenic biofilms that significantly exacerbate these neurotoxic effects. This sequence of investigations reveals that minimal MNPs accumulation can cause oxidative stress and neurodegeneration in human neurons, significantly risking brain health and highlights the need to understand the neurological consequences of inhaling MNPs. Overall, our developed in vitro testing battery has significance in elucidating the effects of environmental factors and their associated pathological mechanisms in human neurons.

Association of transportation noise with cardiovascular diseases

This comprehensive article delves into the intricate and multifaceted issue of noise pollution, shedding light on its diverse sources, profound health implications, and the economic burden it imposes on societies. Noise pollution is an increasingly prevalent environmental challenge, impacting millions of people worldwide, often without their full awareness of its adverse effects. Drawing from a wealth of scientific research, the article underscores the well-established links between noise pollution and a spectrum of health issues, including cardiovascular diseases, sleep disturbances, and psychological stress. While exploring the sources and consequences of noise pollution, the article highlights the urgent need for a holistic and collaborative approach to mitigate its impact. This entails a combination of regulatory measures, technological innovations, urban planning strategies, and public education campaigns. It is increasingly evident that the detrimental effects of noise pollution extend beyond physical health, encompassing mental and social well-being. The article also addresses the synergistic relationship between noise pollution and other environmental stressors, emphasizing the importance of considering noise in conjunction with factors like air pollution and access to green spaces. It examines the potential of green spaces to mitigate the effects of noise pollution and enhance overall health.

Causal relationship between particulate matter and COVID-19 risk: A mendelian randomization study

Background

Observational studies have linked exposure to fine (PM2.5) and coarse (PM10) particulate matter air pollution with adverse COVID-19 outcomes, including higher incidence and mortality. However, some studies questioned the effect of air pollution on COVID-19 susceptibility, raising questions about the causal nature of these associations. To address this, a less biased method like Mendelian randomization (MR) is utilized, which employs genetic variants as instrumental variables to infer causal relationships in observational data.

Method

We performed two-sample MR analysis using public genome-wide association studies data. Instrumental variables correlated with PM2.5 concentration, PM2.5 absorbance, PM2.5-10 concentration and PM10 concentration were identified. The inverse variance weighted (IVW), robust adjusted profile score (RAPS) and generalized summary data-based Mendelian randomization (GSMR) methods were used for analysis.

Results

IVW MR analysis showed PM2.5 concentration [odd ratio (OR) = 3.29, 95% confidence interval (CI) 1.48-7.35, P-value = 0.0036], PM2.5 absorbance (OR = 5.62, 95%CI 1.98-15.94, P-value = 0.0012), and PM10 concentration (OR = 3.74, 95%CI 1.52-9.20, P-value = 0.0041) increased the risk of COVID-19 severity after Bonferroni correction. Further validation confirmed PM2.5 absorbance was associated with heightened COVID-19 severity (OR = 6.05, 95%CI 1.99-18.38, P-value = 0.0015 for RAPS method; OR = 4.91, 95%CI 1.65-14.59, P-value = 0.0042 for GSMR method) and hospitalization (OR = 3.15, 95%CI 1.54-6.47, P-value = 0.0018 for RAPS method). No causal links were observed between particulate matter exposure and COVID-19 susceptibility.

Conclusions

Our study established a causal relationship between smaller particle pollution, specifically PM2.5, and increased risk of COVID-19 severity and hospitalization. These findings highlight the importance of improving air quality to mitigate respiratory disease progression.

Alkylating agents are possible inducers of glioblastoma and other brain tumors

Epidemiological evidence of an association between exposure to chemical carcinogens and an increased risk for development of glioblastoma (GBM) is limited to weak statistical associations in cohorts of firefighters, farmers, residents exposed to air pollution, and soldiers exposed to toxic chemicals (e.g., military burn pits, oil-well fire smoke). A history of ionizing radiation therapy to the head or neck is associated with an increased risk of GBM. Ionizing radiation induces point mutations, frameshift mutations, double-strand breaks, and chromosomal insertions or deletions. Mutational profiles associated with chemical exposures overlap with the broad mutational patterns seen with ionizing radiation. Data on 16 agents (15 chemicals and radio frequency radiation) that induced tumors in the rodent brain were extracted from 602 Technical Reports on 2-years cancer bioassays found in the National Toxicology Program database. Ten of the 15 chemical agents that induce brain tumors are alkylating agents. Three of the 15 chemical agents have idiosyncratic structures and might be alkylating agents. Only two of the 15 chemical agents are definitively not alkylating agents. The rat model is thought to be of possible relevance to humans suggesting that exposure to alkylating chemicals should be considered in epidemiology studies on GBM and other brain tumors.

The burden of brain and central nervous system cancers in Asia from 1990 to 2019 and its predicted level in the next twenty-five years : Burden and prediction model of CNS cancers in Asia

BACKGROUND

Primary brain and central nervous system cancer (collectively called CNS cancers) cause a significant burden to society. The purpose of this study was to evaluate the trends in the burden of CNS cancers from 1990 to 2019 and to predict the incidence and mortality rates and the corresponding numbers for the next 25 years to help countries to understand the trends in its incidence and mortality, and to make better adjustments or formulation of policies and allocation of resources thereby reducing the burden of the disease.

METHODS

The 2019 Global Burden of Disease Study provided incidence rates, death rates, and disability-adjusted life year (DALY) data in Asia from 1990 to 2019. To reflect the trends in the age-standardized incidence, mortality, and DALY rates, the estimated annual percentage change (EAPC) was determined. The Bayesian age-period cohort (BAPC) model was employed to predict the burden of CNS cancers in the next 25 years.

RESULTS

The incidence, death, and DALY rates of CNS cancers all increased from 1990 to 2019. The age-standardized incidence rate (ASIR) for CNS cancers increased from 9.89/100,000 in 1990 to 12.14/100,000 in 2019, with an EAPC of 0.69 (95% confidence interval (CI): 0.65, 0.73). The ASDR and the age-standardized DALY rate both decreased, with EAPCs of - 0.08 and - 0.52, respectively. Before 2005, the age-standardized DALY rate in East Asia was much greater in females than in males, while in Central Asia, the age-standardized death and DALY rates in males both increased sharply after 2000. In contrast to 1990, the caseload increased for the 55-70 years age group. The number of deaths decreased sharply among individuals aged younger than 20 years, especially in East Asia, accounting for only 5.41% of all deaths. The age group with the highest mortality rate was > 60 years, especially in Japan. The ASIR will continue to increase in Asia from 2020 to 2044, and the ASDR will gradually diminish. The incidence and number of deaths from CNS cancers in Asia are expected to increase over the next 25 years, especially among females.

CONCLUSIONS

The study identified an increasing trend in morbidity, mortality and disability-adjusted life-years (DALYs), with differences in age-standardized morbidity rates for different population groups. In addition, it is noteworthy that the burden of disease (as measured by disability-adjusted life-years (DALYs)) is higher among women in Central Asia compared with other regions. ASIR will continue to increase over the next 25 years, with the increase in female cases and mortality expected to be more pronounced. This may need to be further substantiated by additional research, on the basis of which health authorities and policymakers can better utilize limited resources and develop appropriate policies and preventive measures.

Long-term air pollution exposure and malignant intracranial tumours of the central nervous system: a pooled analysis of six European cohorts

BACKGROUND

Risk factors for malignant tumours of the central nervous system (CNS) are largely unknown.

METHODS

We pooled six European cohorts (N = 302,493) and assessed the association between residential exposure to nitrogen dioxide (NO2), fine particles (PM2.5), black carbon (BC), ozone (O3) and eight elemental components of PM2.5 (copper, iron, potassium, nickel, sulfur, silicon, vanadium, and zinc) and malignant intracranial CNS tumours defined according to the International Classification of Diseases ICD-9/ICD-10 codes 192.1/C70.0, 191.0-191.9/C71.0-C71.9, 192.0/C72.2-C72.5. We applied Cox proportional hazards models adjusting for potential confounders at the individual and area-level.

RESULTS

During 5,497,514 person-years of follow-up (average 18.2 years), we observed 623 malignant CNS tumours. The results of the fully adjusted linear analyses showed a hazard ratio (95% confidence interval) of 1.07 (0.95, 1.21) per 10 μg/m³ NO2, 1.17 (0.96, 1.41) per 5 μg/m³ PM2.5, 1.10 (0.97, 1.25) per 0.5 10-5m-1 BC, and 0.99 (0.84, 1.17) per 10 μg/m³ O3.

CONCLUSIONS

We observed indications of an association between exposure to NO2, PM2.5, and BC and tumours of the CNS. The PM elements were not consistently associated with CNS tumour incidence.

Causal relationship between particulate matter 2.5 (PM2.5), PM2.5 absorbance, and COVID-19 risk: A two-sample Mendelian randomisation study

Background

Several observational studies reported on the association between particulate matter ≤2.5μm (PM_2.5) and its absorbance with coronavirus (COVID-19), but none use Mendelian randomisation (MR). To strengthen the knowledge on causality, we examined the association of PM_2.5 and its absorbance with COVID-19 risk using MR.

Methods

We selected genome-wide association study (GWAS) integration data from the UK Biobank and IEU Open GWAS Project for two-sample MR analysis. We used inverse variance weighted (IVW) and its multiple random effects and fixed effects alternatives to generally predict the association of PM_2.5 and its absorbance with COVID-19, and six methods (MR Egger, weighted median, simple mode, weighted mode, maximum-likelihood and MR-PRESSO) as complementary analyses.

Results

MR results suggested that PM_2.5 absorbance was associated with COVID-19 infection (odds ratio (OR) = 2.64; 95% confidence interval (CI) = 1.32-5.27, P = 0.006), hospitalisation (OR = 3.52; 95% CI = 1.05-11.75, P = 0.041) and severe respiratory symptoms (OR = 28.74; 95% CI = 4.00-206.32, P = 0.001) in IVW methods. We observed no association between PM_2.5 and COVID-19.

Conclusions

We found a potential causal association of PM_2.5 absorbance with COVID-19 infection, hospitalisation, and severe respiratory symptoms using MR analysis. Prevention and control of air pollution could help delay and halt the negative progression of COVID-19.

The Relationship between Air Pollution and Brain Cancer: A Systematic Review and Meta-Analysis

Background

There is very little epidemiological evidence on the effects of ambient air pollution on brain tumor risk. The purpose of this study was to determine the relationship between exposure to air pollution and the incidence of brain tumors.

Methods

A comprehensive literature search in five international databases, including PubMed/Medline, ProQuest, Scopus, Embase, and ISI/WOS on April 15, 2019, was conducted. The methodology of the present study was based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) statement. The Newcastle-Ottawa Quality Assessment Form was used to evaluate the quality of the selected papers.

Results

Five studies that measured adult brain tumors as well as their long-term exposure to at least one of the pollutants criteria for air pollution, PM_2.5 absorbance, and proximity to traffic (Trafnear) were reviewed. The results showed that the pooled relative risk (RR) for incidence of brain tumor and long term exposure to Trafnear, PM_2.5, PM_2.5 absorbance, O₃ and NOx were RR = 1.07, (95% CI 0.99-1.16), P = 0.079, for Trafnear; RR = 0.90, (95% CI 0.80-1.00), P = 0.064 for PM_2.5; RR = 1.63, (95% CI 1.04-2.55), P = 0.031 for PM_2.5 absorbance; RR = 1.3, (95% CI 1.03-1.6), P = 0.023 for O₃; and RR = 1.16, (95% CI 0.93-1.45), P = 0.173 for NOx. Exposure to other air pollutants had no statistically significant association with brain tumor incidence.

Conclusion

The results showed that exposure to air pollutants, such as O₃ and PM_2.5 absorbance, had the highest correlation with brain tumor incidence. They also showed an absence of correlation between exposure to certain pollutants (SO₂, CO, NO₂, PM₁₀, PM_2.5) and brain tumor incidence.

The relationship between radiofrequency-electromagnetic radiation from cell phones and brain tumor: The brain tumor incidence trends in South Korea

INTRODUCTION

The aim of this study is to investigate the relationship between the nationwide cell phone subscription rate and the nationwide incidence of brain tumors in South Korea. The nationwide cell phone subscription rate was used as a proxy for the RF-EMR exposure assessment.

METHODS

The data for cell phone subscriptions per 100 persons from 1985 to 2019 were found in the Statistics, International Telecom Union (ITU). The brain tumor incidence data from 1999 to 2018 provided by the South Korea Central Cancer Registry operated by the National Cancer Center were used.

RESULTS

In South Korea, the subscription rate increased from 0 per 100 persons in 1991 to 57 per 100 persons in 2000. The subscription rate became 97 per 100 persons in 2009 and 135 per 100 persons in 2019. For the correlation coefficient between cell phone subscription rate before 10 years and ASIR per 100,000, a positive correlation coefficient with a statistical significance was reported in 3 benign brain tumors (International Classification of Diseases, ICD-10 code, D32, D33, and D32.0) and in 3 malignant brain tumors (ICD-10 code, C71.0, C71.1, and C71.2). Positive correlation coefficients with a statistical significance in malignant brain tumors ranged from 0.75 (95% CI 0.46-0.90) for C71.0 to 0.85 (95% CI 0.63-0.93) for C71.1.

DISCUSSION

In consideration of the fact that the main route for RF-EMR exposure has been through the frontotemporal side of the brain (the location of both ears), the positive correlation coefficient with a statistical significance in the frontal lobe (C71.1) and temporal lobe (C71.2) can be understood. Statistically insignificant results from recent cohort and large population international studies and contrasting results from many previous case-control studies could indicate a difficulty in identifying a factor as a determinant of a disease in ecological study design.

Overview of PM2.5 and health outcomes: Focusing on components, sources, and pollutant mixture co-exposure

PM_2.5 varies in source and composition over time and space as a complicated mixture. Consequently, the health effects caused by PM_2.5 varies significantly over time and generally exhibit significant regional variations. According to numerous studies, a notable relationship exists between PM_2.5 and the occurrence of many diseases, such as respiratory, cardiovascular, and nervous system diseases, as well as cancer. Therefore, a comprehensive understanding of the effect of PM_2.5 on human health is critical. The toxic effects of various PM_2.5 components, as well as the overall toxicity of PM_2.5 are discussed in this review to provide a foundation for precise PM_2.5 emission control. Furthermore, this review summarizes the synergistic effect of PM_2.5 and other pollutants, which can be used to draft effective policies.

Particle Number Concentration Measurements on Public Transport in Bangkok, Thailand

Traffic is a major source of particulate pollution in large cities, and particulate matter (PM) level in Bangkok often exceeds the World Health Organisation limits. While PM_2.5 and PM₁₀ are both measured in Bangkok regularly, the sub-micron range of PM, of specific interest in regard to possible adverse health effects, is very limited. In the study, particle number concentration (PNC) was measured on public transport in Bangkok. A travel route through Bangkok using the state railway, the mass rapid transport underground system, the Bangkok Mass Transit System (BTS) Skytrain and public buses on the road network, with walking routes between, was taken whilst measuring particle levels with a hand-held concentration particle counter. The route was repeated 19 times covering different seasons during either morning or evening rush hours. The highest particle concentrations were found on the state railway, followed by the bus, the BTS Skytrain and the MRT underground with measured peaks of 350,000, 330,000, 33,000 and 9000 cm^-3, respectively, though particle numbers over 100,000 cm^-3 may be an underestimation due to undercounting in the instrument. Inside each form of public transport, particle numbers would peak when stopping to collect passengers (doors opening) and decay with a half-life between 2 and 3 min. There was a weak correlation between particle concentration on bus, train and BTS and Skytrain with carbon monoxide concentration, as measured at a fixed location in the city.

Respiratory Health Effects of In Vivo Sub-Chronic Diesel and Biodiesel Exhaust Exposure

Biodiesel, which can be made from a variety of natural oils, is currently promoted as a sustainable, healthier replacement for commercial mineral diesel despite little experimental data supporting this. The aim of our research was to investigate the health impacts of exposure to exhaust generated by the combustion of diesel and two different biodiesels. Male BALB/c mice (n = 24 per group) were exposed for 2 h/day for 8 days to diluted exhaust from a diesel engine running on ultra-low sulfur diesel (ULSD) or Tallow or Canola biodiesel, with room air exposures used as control. A variety of respiratory-related end-point measurements were assessed, including lung function, responsiveness to methacholine, airway inflammation and cytokine response, and airway morphometry. Exposure to Tallow biodiesel exhaust resulted in the most significant health impacts compared to Air controls, including increased airway hyperresponsiveness and airway inflammation. In contrast, exposure to Canola biodiesel exhaust resulted in fewer negative health effects. Exposure to ULSD resulted in health impacts between those of the two biodiesels. The health effects of biodiesel exhaust exposure vary depending on the feedstock used to make the fuel.

Impacts of Environmental Pollution on Brain Tumorigenesis

Pollutants consist of several components, known as direct or indirect mutagens, that can be associated with the risk of tumorigenesis. The increased incidence of brain tumors, observed more frequently in industrialized countries, has generated a deeper interest in examining different pollutants that could be found in food, air, or water supply. These compounds, due to their chemical nature, alter the activity of biological molecules naturally found in the body. The bioaccumulation leads to harmful effects for humans, increasing the risk of the onset of several pathologies, including cancer. Environmental components often combine with other risk factors, such as the individual genetic component, which increases the chance of developing cancer. The objective of this review is to discuss the impact of environmental carcinogens on modulating the risk of brain tumorigenesis, focusing our attention on certain categories of pollutants and their sources.

Ambient Fine Particulate Matter and Cancer: Current Evidence and Future Perspectives

The high incidence of cancer has placed an enormous health and economic burden on countries around the world. In addition to evidence of epidemiological studies, conclusive evidence from animal experiments and mechanistic studies have also shown that morbidity and mortality of some cancers can be attributed to ambient fine particulate matter (PM_2.5) exposure, especially in lung cancer. However, the underlying carcinogenetic mechanisms of PM_2.5 remain unclear. Furthermore, in terms of risks of other types of cancer, both epidemiological and mechanistic evidence are more limited and scattered, and the results are also inconsistent. In order to sort out the carcinogenic effect of PM_2.5, this paper reviews the association of cancers with PM_2.5 based on epidemiological and biological evidence including genetic, epigenetic, and molecular mechanisms. The limitations of existing researches and the prospects for the future are also well clarified in this paper to provide insights for future studies.

Determination of optimal height of barriers to reduce the amount of pollution in the viaduct settings in an idealized urban canyon: a numerical study

In this work, we numerically investigate the process of atmospheric air pollution in idealized urban canyons along the road in the presence of a viaduct, taking into account different height of barriers. To solve this problem, the 3D Reynolds-averaged Navier-Stokes equations (RANS) were used. The closure of this system of equations was achieved by using various turbulent models. The verification of the mathematical model and the numerical algorithm was carried out using a test problem. The obtained results using various turbulent models were compared with experimental data and calculated results of other authors. The main problem considered in this work is characterized as follows: assessment of emissions of pollutants between buildings using barriers of various types in the presence of a viaduct. Computational results have shown that the barrier viaduct plays a large role in improving air quality in urban canyons. So, for example, a barrier erected on a viaduct with a height of 2 m reduces the concentration value to a cross-section x = 84 by more than 2 times in comparison with the case of a complete absence of protective barriers. A similar situation was observed with barriers erected above the earth's surface: located along the road, they also significantly reduce the value of the concentration of pollutants. Thus, the presence of barriers in both cases is necessary to prevent the dispersion and deposition of pollutants.

Particulate Matters Affecting lncRNA Dysregulation and Glioblastoma Invasiveness: In Silico Applications and Current Insights

With a reported rise in global air pollution, more than 50% of the population remains exposed to toxic air pollutants in the form of particulate matters (PMs). PMs, from various sources and of varying sizes, have a significant impact on health as long-time exposure to them has seen a correlation with various health hazards and have also been determined to be carcinogenic. In addition to disrupting known cellular pathways, PMs have also been associated with lncRNA dysregulation-a factor that increases predisposition towards the onset or progression of cancer. lncRNA dysregulation is further seen to mediate glioblastoma multiforme (GBM) progression. The vast array of information regarding cancer types including GBM and its various precursors can easily be obtained via innovative in silico approaches in the form of databases such as GEO and TCGA; however, a need to obtain selective and specific information correlating anthropogenic factors and disease progression-in the case of GBM-can serve as a critical tool to filter down and target specific PMs and lncRNAs responsible for regulating key cancer hallmarks in glioblastoma. The current review article proposes an in silico approach in the form of a database that reviews current updates on correlation of PMs with lncRNA dysregulation leading to GBM progression.

Oncolytic viruses as a promising therapeutic strategy against the detrimental health impacts of air pollution: The case of glioblastoma multiforme

Human livelihood highly depends on applying different sources of energy whose utilization is associated with air pollution. On the other hand, air pollution may be associated with glioblastoma multiforme (GBM) development. Unlike other environmental causes of cancer (e.g., irradiation), air pollution cannot efficiently be controlled by geographical borders, regulations, and policies. The unavoidable exposure to air pollution can modify cancer incidence and mortality. GBM treatment with chemotherapy or even its surgical removal has proven insufficient (100% recurrence rate; patient's survival mean of 15 months; 90% fatality within five years) due to glioma infiltrative and migratory capacities. Given the barrage of attention and research investments currently plowed into next-generation cancer therapy, oncolytic viruses are perhaps the most vigorously pursued. Provision of an insight into the current state of the research and future direction is essential for stimulating new ideas with the potentials of filling research gaps. This review manuscript aims to overview types of brain cancer, their burden, and different causative agents. It also describes why air pollution is becoming a concerning factor. The different opinions on the association of air pollution with brain cancer are reviewed. It tries to address the significant controversy in this field by hypothesizing the air-pollution-brain-cancer association via inflammation and atopic conditions. The last section of this review deals with the oncolytic viruses, which have been used in, or are still under clinical trials for GBM treatment. Engineered adenoviruses (i.e., DNX-2401, DNX-2440, CRAd8-S-pk7 loaded Neural stem cells), herpes simplex virus type 1 (i.e., HSV-1 C134, HSV-1 rQNestin34.5v.2, HSV-1 G207, HSV-1 M032), measles virus (i.e., MV-CEA), parvovirus (i.e., ParvOryx), poliovirus (i.e., Poliovirus PVSRIPO), reovirus (i.e., pelareorep), moloney murine leukemia virus (i.e., Toca 511 vector), and vaccinia virus (i.e., vaccinia virus TG6002) as possible life-changing alleviations for GBM have been discussed. To the best of our knowledge, this review is the first review that comprehensively discusses both (i) the negative/positive association of air pollution with GBM; and (ii) the application of oncolytic viruses for GBM, including the most recent advances and clinical trials. It is also the first review that addresses the controversies over air pollution and brain cancer association. We believe that the article will significantly appeal to a broad readership of virologists, oncologists, neurologists, environmentalists, and those who work in the field of (bio)energy. Policymakers may also use it to establish better health policies and regulations about air pollution and (bio)fuels exploration, production, and consumption.

Aerosol mass and size-resolved metal content in urban Bangkok, Thailand

Inhalable particulate matter (PM) is a health concern, and people living in large cities such as Bangkok are exposed to high concentrations. This exposure has been linked to respiratory and cardiac diseases and cancers of the lung and brain. Throughout 2018, PM was measured in northern Bangkok near a toll road (13.87°N, 100.58°E) covering all three seasons (cool, hot and rainy). PM₁₀ was measured in 24- and 72-h samples. On selected dates aerodynamic size and mass distribution were measured as 3-day samples from a fixed 5th floor inlet. Particle number concentration was measured from the 5th floor inlet and in roadside survey measurements. There was a large fraction of particle number concentration in the sub-micron range, which showed the greatest variability compared with larger fractions. Metals associated with combustion sources were most found on the smaller size fraction of particles, which may have implications for associated adverse health outcomes because of the likely location of aerosol deposition in the distal airways of the lung. PM₁₀ samples varied between 30 and 100 μg m^-3, with highest concentrations in the cool season. The largest metal fractions present in the PM₁₀ measurements were calcium, iron and magnesium during the hot season with average airborne concentrations of 13.2, 3.6 and 2.0 μg m^-3, respectively. Copper, zinc, arsenic, selenium, molybdenum, cadmium, antimony and lead had large non-crustal sources. Principal component analysis (PCA) identified likely sources of the metals as crustal minerals, tailpipe exhaust and non-combustion traffic. A health risk analysis showed a higher risk of both carcinogenic and non-carcinogenic health effects in the drier seasons than the wet season due to ingestion of nickel, arsenic, cadmium and lead.

Trend of incidence and mortality of brain and central nervous system cancer in Iran from 1990 to 2017: A global burden of disease-based study

Background: Brain and central nervous system (CNS) cancers make up about 3% of all cancers around the world and are more common among men than women. Present study aimed to evaluate the occurrence trend of brain and CNS cancers in Iran from 1990 to 2017. Methods: This study using global burden of disease (GBD) 1990 to 2017 data demonstrated the trend of incidence and mortality of brain and nervous system cancer in Iran. All-age, sex-based, age-standardized, age-specific (from 1990 to 2017), and age distribution of incidence and mortality rates of brain and nervous system cancer were estimated in Iran during 2017. Results: Both incidence and mortality rates of brain and nervous system cancer increased from 1990 to 2005 in Iran, Eastern Mediterranean Region, and global level. During 1990, incidence and mortality rates of brain and nervous system cancer were higher in women than men, but gradually both rates increased in men and exceeded women in Iran. From 1990 to 2017, the value of age-adjusted rate was higher than all-age rate of brain and nervous system cancer. The most incidence and mortality of brain and nervous system cancer from 1990 to 2017 occurred in age group of > 70 and the least values were seen in 15-49-year-old group in Iran. Conclusion: The brain tumor occurrence and mortality in Iran was higher than other Eastern Mediterranean Region countries. Incidence and mortality of this cancer has an increasing trend in Iran and this trend somewhat was independent from population aging.

PM2.5 exposure and cervical cancer survival in Liaoning Province, northeastern China

Particulate matter with a diameter of 2.5 μm or less (PM_2.5) has frequently been reported to be associated with an increased incidence of cancer, but few studies have explored the association between PM_2.5 exposure and cancer survival. We retrospectively analyzed the association between PM_2.5 exposure and the overall survival (OS) of cervical cancer patients residing in 14 urban areas of Liaoning Province, northeastern China, during January 2014-October 2021. Patients from urban areas who completed the recommended treatments with complete follow-up information were included. The PM_2.5 monitoring data of each urban area of Liaoning Province were retrieved, and individual exposure to PM_2.5 after diagnosis was calculated as the average daily concentration in the city of residence from the date of discharge to the date of death or the last follow-up. Log-rank tests and Cox regression were performed to examine the relationship between PM_2.5 exposure and cervical cancer survival. A total of 1753 cervical cancer patients were finally included, among whom 804 (45.9%) were from Shenyang City, the capital of Liaoning Province. The median average daily concentration of PM_2.5 to which the patients were exposed was 45.0 (interquartile range 38.2-50.0) μg/m³. Both log-rank tests (grouped by quartiles, p < 0.001) and Cox regression (continuous, HR = 1.06, 95% CI 1.04-1.08) indicated that PM_2.5 was significantly associated with shorter OS. Sensitivity analysis also confirmed the robustness of our findings. From the subgroup analysis, only the OS of stage II and stage III patients was associated with PM exposure. Our findings provide the insight that PM_2.5 exposure might be associated with shorter OS of cervical cancer patients.

In utero particulate matter exposure in association with newborn mitochondrial ND4L10550A>G heteroplasmy and its role in overweight during early childhood

BACKGROUND

Mitochondria play an important role in the energy metabolism and are susceptible to environmental pollution. Prenatal air pollution exposure has been linked with childhood obesity. Placental mtDNA mutations have been associated with prenatal particulate matter exposure and MT-ND4L_10550A>G heteroplasmy has been associated with BMI in adults. Therefore, we hypothesized that in utero PM_2.5 exposure is associated with cord blood MT-ND4L_10550A>G heteroplasmy and early life growth. In addition, the role of cord blood MT-ND4L_10550A>G heteroplasmy in overweight during early childhood is investigated.

METHODS

This study included 386 mother-newborn pairs. Outdoor PM_2.5 concentrations were determined at the maternal residential address. Cord blood MT-ND4L_10550A>G heteroplasmy was determined using Droplet Digital PCR. Associations were explored using logistic regression models and distributed lag linear models. Mediation analysis was performed to quantify the effects of prenatal PM_2.5 exposure on childhood overweight mediated by cord blood MT-ND4L_10550A>G heteroplasmy.

RESULTS

Prenatal PM_2.5 exposure was positively associated with childhood overweight during the whole pregnancy (OR = 2.33; 95% CI: 1.20 to 4.51; p = 0.01), which was mainly driven by the second trimester. In addition, prenatal PM_2.5 exposure was associated with cord blood MT-ND4L_10550A>G heteroplasmy from gestational week 9 - 13. The largest effect was observed in week 10, where a 5 µg/m³ increment in PM_2.5 was linked with cord blood MT-ND4L_10550A>G heteroplasmy (OR = 0.93; 95% CI: 0.87 to 0.99). Cord blood MT-ND4L_10550A>G heteroplasmy was also linked with childhood overweight (OR = 3.04; 95% CI: 1.15 to 7.50; p = 0.02). The effect of prenatal PM_2.5 exposure on childhood overweight was mainly direct (total effect OR = 1.18; 95% CI: 0.99 to 1.36; natural direct effect OR = 1.20; 95% CI: 1.01 to 1.36)) and was not mediated by cord blood MT-ND4L_10550A>G heteroplasmy.

CONCLUSIONS

Cord blood MT-ND4L_10550A>G heteroplasmy was linked with childhood overweight. In addition, in utero exposure to PM_2.5 during the first trimester of pregnancy was associated with cord blood MT-ND4L_10550A>G heteroplasmy in newborns. Our analysis did not reveal any mediation of cord blood MT-ND4L_10550A>G heteroplasmy in the association between PM_2.5 exposure and childhood overweight.

Outdoor air quality and human health: An overview of reviews of observational studies

The epidemiological evidence supporting putative associations between air pollution and health-related outcomes continues to grow at an accelerated pace with a considerable heterogeneity and with varying consistency based on the outcomes assessed, the examined surveillance system, and the geographic region. We aimed to evaluate the strength of this evidence base, to identify robust associations as well as to evaluate effect variation. An overview of reviews (umbrella review) methodology was implemented. PubMed and Scopus were systematically screened (inception-3/2020) for systematic reviews and meta-analyses examining the association between air pollutants, including CO, NO_X, NO₂, O₃, PM₁₀, PM_2.5, and SO₂ and human health outcomes. The quality of systematic reviews was evaluated using AMSTAR. The strength of evidence was categorized as: strong, highly suggestive, suggestive, or weak. The criteria included statistical significance of the random-effects meta-analytical estimate and of the effect estimate of the largest study in a meta-analysis, heterogeneity between studies, 95% prediction intervals, and bias related to small study effects. Seventy-five systematic reviews of low to moderate methodological quality reported 548 meta-analyses on the associations between outdoor air quality and human health. Of these, 57% (N = 313) were not statistically significant. Strong evidence supported 13 associations (2%) between elevated PM_2.5, PM₁₀, NO₂, and SO₂ concentrations and increased risk of cardiorespiratory or pregnancy/birth-related outcomes. Twenty-three (4%) highly suggestive associations were identified on elevated PM_2.5, PM₁₀, O₃, NO₂, and SO₂ concentrations and increased risk of cardiorespiratory, kidney, autoimmune, neurodegenerative, cancer or pregnancy/birth-related outcomes. Sixty-seven (12%), and 132 (24%) meta-analyses were graded as suggestive, and weak, respectively. Despite the abundance of research on the association between outdoor air quality and human health, the meta-analyses of epidemiological studies in the field provide evidence to support robust associations only for cardiorespiratory or pregnancy/birth-related outcomes.

Long-Term Exposure to Air Pollution Associates the Risk of Benign Brain Tumor: A Nationwide, Population-Based, Cohort Study in Taiwan

Air pollutants as risk factors for benign brain tumor (BBT) remain unclear. Therefore, we conducted a nationwide retrospective cohort study by integrating the patients’ clinical data and daily air quality data to assess the environmental risk factors of BBT in Taiwan.Daily air quality data were categorized into quartiles (Q1 to Q4). The adjusted hazard ratio (aHR) was evaluated by comparing the BBT incidence rate of the subjects in Q2–Q4 with that of the subjects in Q1 (the lowest concentration of air pollutants). A total of 161,213 subjects were enrolled in the study. Among the air pollutants tested, the aHR of BBT was significantly higher in the subjects who were exposed to the highest level (Q4) of CO (aHR 1.37, 95% CI 1.08–1.74), NO2 (aHR 1.40, 95% CI 1.09–1.78), and PM2.5 (aHR 1.30, 95% CI 1.02–1.65) than that in the subjects who were exposed to the lowest level (Q1). No significant risk association of BBT with SO2 and PM10 exposure was observed. The results revealed that long-term exposure to air pollutants, particularly CO, NO2, and PM2.5, is associated with the risk of BBT.

Cohort studies of long-term exposure to outdoor particulate matter and risks of cancer: A systematic review and meta-analysis

Robust evidence is needed for the hazardous effects of outdoor particulate matter (PM) on mortality and morbidity from all types of cancers. To summarize and meta-analyze the association between PM and cancer, published articles reporting associations between outdoor PM exposure and any type of cancer with individual outcome assessment that provided a risk estimate in cohort studies were identified via systematic searches. Of 3,256 records, 47 studies covering 13 cancer sites (30 for lung cancer, 12 for breast cancer, 11 for other cancers) were included in the quantitative evaluation. The pooled relative risks (RRs) for lung cancer incidence or mortality associated with every 10-μg/m³ PM_2.5 or PM₁₀ were 1.16 (95% confidence interval [CI], 1.10–1.23; I² = 81%) or 1.22 (95% CI, 1.02–1.45; I² = 96%), respectively. Increased but non-significant risks were found for breast cancer. Other cancers were shown to be associated with PM exposure in some studies but not consistently and thus warrant further investigation.

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Updated evidence for the association between PM and lung cancer risk has been provided

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Associations between PM and cancer risks from 13 sites were summarized

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Further studies should be conducted to fill the research gaps

Metformin and Risk of Malignant Brain Tumors in Patients with Type 2 Diabetes Mellitus

The risk of malignant brain tumors associated with metformin use has rarely been investigated in humans. This retrospective cohort study investigated such an association. Patients with new-onset type 2 diabetes mellitus diagnosed from 1999 to 2005 in the nationwide database of Taiwan’s national health insurance were used to enroll study subjects. We first identified an unmatched cohort of 153,429 ever users and 16,222 never users of metformin. A cohort of 16,222 ever users and 16,222 never users matched on propensity score was then created from this unmatched cohort. All patients were followed up from 1 January 2006 until 31 December 2011. The incidence density was calculated and hazard ratios were derived from Cox regression incorporated with the inverse probability of treatment weighting using a propensity score. The results showed that 27 never users and 155 ever users developed malignant brain tumors in the unmatched cohort. The incidence rate was 37.11 per 100,000 person-years in never users and 21.39 per 100,000 person-years in ever users. The overall hazard ratio comparing ever users versus never users was 0.574 (95% confidence interval: 0.381–0.863). The respective hazard ratios comparing the first (<27.13 months), second (27.13–58.33 months), and third (>58.33 months) tertiles of cumulative duration of metformin therapy versus never users were 0.897 (0.567–1.421), 0.623 (0.395–0.984), and 0.316 (0.192–0.518). In the matched cohort, the overall hazard ratio was 0.317 (0.149–0.673) and the respective hazard ratios were 0.427 (0.129–1.412), 0.509 (0.196–1.322), and 0.087 (0.012–0.639) for the first, second, and third tertile of cumulative duration of metformin therapy. In conclusion, this study shows a risk reduction of malignant brain tumors associated with metformin use in a dose–response pattern. The risk reduction is more remarkable when metformin has been used for approximately 2–5 years.

Primary central nervous system tumors in Sergipe, Brazil: descriptive epidemiology between 2010 and 2018

BACKGROUND

Central nervous system (CNS) tumors are a heterogeneous group with high morbidity and mortality.

OBJECTIVES

To describe the epidemiology of primary CNS tumors diagnosed in the state of Sergipe from 2010 to 2018.

METHODS

We evaluated histopathological and immunohistochemical reports on primary CNS tumors diagnosed in Sergipe, Brazil, between 2010 and 2018 and collected data regarding age, sex, location, World Health Organization (WHO) classification and histology.

RESULTS

Altogether, 861 primary CNS tumors were found. Tumors in brain locations occurred most frequently (50.8%; n=437). The neoplasms observed were most prevalent in the age range 45‒54 years (20.4%; n=176). Grade I tumors occurred most frequently, corresponding to 38.8% of the cases (n=38) in the age group of 0‒14 years, and 44.6% (n=340) in the population ≥15 years old. Between 0 and 14 years of age, other astrocytic tumors were the most prevalent (29.6%; n=29). In the age group between 15 and 34, gliomas were the most frequent (32.7%; n=54). Meningiomas predominated in the age group of 35 years and above, comprising 47.5% of cases (n=206) in the 35‒74 age group; and 61.2% (n=30) among patients over 75 years old.

CONCLUSION

The epidemiology of primary CNS tumors in Sergipe between 2010 and 2018 is consistent with data in other current studies on the subject. Studies on the epidemiological evolution of these entities in Sergipe are needed.

Brain cancer incidence: a comparison of active-duty military and general populations

BACKGROUND

In the USA, brain cancer disproportionately affects young adults. The US military has a younger age structure than the general population and may have differential exposures related to brain cancer. This study aimed to compare the incidence rates of brain cancer in the active-duty military and general populations to provide clues for future etiologic research. The rates between military service branches were also compared.

METHODS

The data for this study were from the Department of Defense's Automated Central Tumor Registry (ACTUR) and the National Cancer Institute's Surveillance, Epidemiology, and End Results 9 (SEER-9) registries. Age- and sex-adjusted incidence rates of malignant neuroepithelial brain cancer among adults 20-54 years of age from 1990-2013 were calculated and compared between the two populations, given as incidence rate ratios (IRRs) with 95% confidence intervals (CIs).

RESULTS

The age and sex-adjusted incidence rate for malignant neuroepithelial brain cancer was significantly lower in the active-duty population than in the US general population (IRR = 0.62, 95% CI,  0.56-0.68). The reduced incidence rate in the active-duty population was observed in men, all races, individuals 20-44 of age, and for all histological subtypes and time periods assessed. There were no significant differences in rates between the military service branches.

CONCLUSION

The incidence rates of neuroepithelial brain cancer were lower in the active-duty military population than the US general population. This study highlights the need for more research to enhance our understanding of variations in brain cancer incidence between these two populations.

Association between Airport-Related Ultrafine Particles and Risk of Malignant Brain Cancer: A Multiethnic Cohort Study

Ultrafine particles (UFP; diameter less than or equal to 100 nm) may reach the brain via systemic circulation or the olfactory tract and have been implicated in the risk of brain tumors. The effects of airport-related UFP on the risk of brain tumors are not known. Here we determined the association between airport-related UFP and risk of incident malignant brain cancer (n = 155) and meningioma (n = 420) diagnosed during 16.4 years of follow-up among 75,936 men and women residing in Los Angeles County from the Multiethnic Cohort study. UFP exposure from aircrafts was estimated for participants who lived within a 53 km × 43 km grid area around the Los Angeles International Airport (LAX) from date of cohort entry (1993-1996) through December 31, 2013. Cox proportional hazards models were used to estimate the effects of time-varying, airport-related UFP exposure on risk of malignant brain cancer and meningioma, adjusting for sex, race/ethnicity, education, and neighborhood socioeconomic status. Malignant brain cancer risk in all subjects combined increased 12% [95% confidence interval (CI), 0.98-1.27] per interquartile range (IQR) of airport-related UFP exposure (∼6,700 particles/cm³) for subjects with any address in the grid area surrounding the LAX airport. In race/ethnicity-stratified analyses, African Americans, the subgroup who had the highest exposure, showed a HR of 1.32 (95% CI, 1.07-1.64) for malignant brain cancer per IQR in UFP exposure. UFP exposure was not related to risk of meningioma overall or by race/ethnicity. These results support the hypothesis that airport-related UFP exposure may be a risk factor for malignant brain cancers. SIGNIFICANCE: Malignant brain cancer risk increases with airport-related UFP exposure, particularly among African Americans, suggesting UFP exposure may be a modifiable risk factor for malignant brain cancer.

Mesenchymal Stromal Cell-derived Extracellular Vesicles in Preclinical Animal Models of Tumor Growth: Systematic Review and Meta-analysis

BACKGROUND

Mesenchymal stromal cell derived extracellular vesicles (MSC-EVs) have been implicated in the regulation of tumor growth. Studies remain preclinical with effects ranging from inhibition of tumor growth to cancer progression. A systematic review and meta-analysis is needed to clarify the effect of MSC-EVs on tumor growth to facilitate potential translation to clinical trials.

METHODS

A systematic search of the literature (MEDLINE, Embase, and BIOSIS databases to June 1, 2019) identified all pre-clinical controlled studies investigating the effect of MSC-EVs on tumor growth. Study selection and data extraction were performed in duplicate. Potential risk of bias was assessed using the SYRCLE tool. A random effects meta-analysis of reduction in tumor weight/volume (primary outcome) was performed.

RESULTS

We identified 29 articles and 22 reported data on tumor responses that were included for meta-analysis. Studies were associated with unclear risk of bias in a large proportion of domains in accordance with the SYRCLE tool for determining risk of bias in preclinical studies. A high risk of bias was not identified in any study. MSC-EVs had a mixed response on tumor progression with some studies reporting inhibition of tumor growth and others reporting tumor progression. Overall, MSC-EVs exerted a non-significant reduction in tumor growth compared to controls (standardized mean difference (SMD) -0.80, 95 % CI -1.64 to 0.03, p = 0.06, I² = 87 %). Some studies reported increased tumor growth which aligned with their stated hypothesis and some interrogated mechanisms in cancer biology. EVs isolated from MSCs that overexpressed anti-tumor RNAs were associated with significant tumor reduction in meta-analysis (SMD - 2.40, 95 % CI -3.36 to -1.44, p < 0.001). Heterogeneity between studies was observed and included aspects of study design such as enrichment of MSC-EVs with specific anti-tumor molecules, tissue source of MSCs, method of EV isolation, characterization of MSCs and EVs, dosage and administration schedules, and tissue type and source of tumor cells studied.

CONCLUSIONS

MSC-EVs are associated with mixed effects on tumor growth in animal models of cancer. In studies where anti-tumor RNAs are packaged in EVs, a significant reduction in tumor growth was observed. Reducing heterogeneity in study design may accelerate our understanding of the potential effects of MSC-EVs on cancer. [274 words] Forest plot of MSC-EV effect on tumor growth accordinggenetic modification of EVs in animal studies identified from a systematicreview of the literature. All cohorts from studies with multiple interventiongroups are presented separately with control groups divided equally among thegroups. M, modified; H, hypoxia.

Within-city Spatial Variations in Ambient Ultrafine Particle Concentrations and Incident Brain Tumors in Adults

BACKGROUND

Ambient ultrafine particles (UFPs, <0.1 µm) can reach the human brain, but to our knowledge, epidemiologic studies have yet to evaluate the relation between UFPs and incident brain tumors.

METHODS

We conducted a cohort study of within-city spatial variations in ambient UFPs across Montreal and Toronto, Canada, among 1.9 million adults included in multiple cycles of the Canadian Census Health and Environment Cohorts (1991, 1996, 2001, and 2006). UFP exposures (3-year moving averages) were assigned to residential locations using land-use regression models with exposures updated to account for residential mobility within and between cities. We followed cohort members for malignant brain tumors (ICD-10 codes C71.0-C71.9) between 2001 and 2016; Cox proportional hazards models (stratified by age, sex, immigration status, and census cycle) were used to estimate hazard ratios (HRs) adjusting for fine particle mass concentrations (PM2.5), nitrogen dioxide (NO2), and various sociodemographic factors.

RESULTS

In total, we identified 1,400 incident brain tumors during the follow-up period. Each 10,000/cm increase in UFPs was positively associated with brain tumor incidence (HR = 1.112, 95% CI = 1.042, 1.188) after adjusting for PM2.5, NO2, and sociodemographic factors. Applying an indirect adjustment for cigarette smoking and body mass index strengthened this relation (HR = 1.133, 95% CI = 1.032, 1.245). PM2.5 and NO2 were not associated with an increased incidence of brain tumors.

CONCLUSIONS

Ambient UFPs may represent a previously unrecognized risk factor for incident brain tumors in adults. Future studies should aim to replicate these results given the high prevalence of UFP exposures in urban areas.

Biotoxic effects and gene expression regulation of urban PM2.5 in southwestern China

Atmospheric fine particulate matter (PM_2.5) causes severe haze in China and is regarded as a threat to human health. The health effects of PM_2.5 vary location by location due to the variation in size distribution, chemical composition, and sources. In this study, the cytotoxicity effect, oxidative stress, and gene expression regulation of PM_2.5 in Chengdu and Chongqing, two typical urban areas in southern China, were evaluated. Urban PM_2.5 in summer and winter significantly inhibited cell viability and increased reactive oxygen species (ROS) levels in A549 cells. Notably, PM_2.5 in winter exhibited higher cytotoxicity and ROS level than summer. Moreover, in this study, PM_2.5 commonly induced cancer-related gene expression such as cell adhesion molecule 1 (PECAM1), interleukin 24 (IL24), and cytochrome P450 (CYP1A1); meanwhile, PM_2.5 commonly acted on cancer-related biological functions such as cell-substrate junction, cell-cell junction, and focal adhesion. In particular, PM_2.5 in Chengdu in summer had the highest carcinogenic potential among PM_2.5 at the two sites in summer and winter. Importantly, cancer-related genes were uniquely targeted by PM_2.5, such as epithelial splicing regulatory protein 1 (ESRP1) and membrane-associated ring-CH-type finger 1 (1-Mar) by Chengdu summer PM_2.5; collagen type IX alpha 3 chain (COL9A3) by Chengdu winter PM_2.5; SH2 domain-containing 1B (SH2D1B) by Chongqing summer PM_2.5; and interleukin 1 receptor-like 1 (IL1RL1) and zinc finger protein 42 (ZNF423) by Chongqing winter PM_2.5. Meanwhile, important cancer-related biological functions were specially induced by PM_2.5, such as cell cycle checkpoint by Chengdu summer PM_2.5; macromolecule methylation by Chengdu winter PM_2.5; endoplasmic reticulum-Golgi intermediate compartment membrane by Chongqing summer PM_2.5; and cellular lipid catabolic process by Chongqing winter PM_2.5. Conclusively, in the typical urban areas of southern China, both summer and winter PM_2.5 illustrated significant gene regulation effects. This study contributes to evaluating the adverse health effects of PM_2.5 in southern China and providing public health suggestions for policymakers.

Assessment of the ability of roadside vegetation to remove particulate matter from the urban air

The development of urbanised areas together with the growing transport infrastructure and traffic volume are the main cause of air quality deterioration due to the increasing concentrations of particulate matter. Dust pollution is a threat to human health. It can cause the development of lung, larynx or circulatory system cancer. Due to the ability to accumulate dust particles on the leaf surface, the contribution of trees in the process of phytoremediation of air pollution has started to be appreciated. An analysis of the elemental composition of particulate matter (PM) stored on the leaves surface was also carried out, which showed high average concentration of: C > O > Si > Fe (above 8wt.%). It was also observed single particles with a high concentration of heavy metals: Ti, Mn, Ba, Zn, Cr, Pb, Sn, Ni and REE (rare earth elements). The major origin of PM are vehicular emissions, soil and re-suspended road dust. This paper presents also a comparison of selected tree, shrub and vine species differing in their ability to accumulate particulate matter. It was experimentally determined the average leaf surface of individual plant species and established the amount of particulate matter with aerodynamic diameter between 10 and 100 μm, 2.5 and 10 μm, and 0.2 and 2.5 μm deposited on the leaf surface and in waxes. Some species of vines (Parthenocissus quinquefolia), shrubs (Forsythia x intermediata) and coniferous trees, such as Betula pendula 'Youngii', Quercus rubra, Cratageus monogyna, Acer pseduoplatanus, Tilia cordata Mill. or Platanus orientalis turned out to be the most efficient in the process of phylloremediation.

Air Pollution and Central Nervous System Disease: A Review of the Impact of Fine Particulate Matter on Neurological Disorders

Background: It is widely known that the harmful effects of fine dust can cause various diseases. Research on the correlation between fine dust and health has been mainly focused on lung and cardiovascular diseases. By contrast, the effects of air pollution on the central nervous system (CNS) are not broadly recognized.

Findings: Air pollution can cause diverse neurological disorders as the result of inflammation of the nervous system, oxidative stress, activation of microglial cells, protein condensation, and cerebral vascular-barrier disorders, but uncertainty remains concerning the biological mechanisms by which air pollution produces neurological disease. Neuronal cell damage caused by fine dust, especially in fetuses and infants, can cause permanent brain damage or lead to neurological disease in adulthood.

Conclusion: It is necessary to study the air pollution–CNS disease connection with particular care and commitment. Moreover, the epidemiological and experimental study of the association between exposure to air pollution and CNS damage is critical to public health and quality of life. Here, we summarize the correlations between fine dust exposure and neurological disorders reported so far and make suggestions on the direction future research should take.

Long-term trends in the contribution of PM2.5 sources to organic carbon (OC) in the Los Angeles basin and the effect of PM emission regulations

This study aimed to investigate the long-term variations in the contributions of emission sources to ambient PM_2.5 organic carbon (OC) in central Los Angeles (CELA) and Riverside using the Chemical Speciation Network (CSN) database in the 2005-2015 period, during which several federal and state PM-based regulations were implemented to reduce tailpipe emissions in the region. The measured concentrations of OC, OC volatility fractions (i.e., OC₁, OC₂, and OC₃), elemental carbon (EC), ozone (O₃), sulfate, the ratio of potassium ion to potassium (K⁺/K), and selected metal elements were used as the input to the positive matrix factorization (PMF) model. PMF resolved tailpipe emissions, non-tailpipe emissions, secondary organic aerosols (SOA), biomass burning, and local industrial activities as the main sources contributing to ambient OC at both sampling sites. Vehicular exhaust emissions, non-tailpipe emissions, and SOA were dominant sources of OC across our sampling sites, accounting cumulatively for more than 80% of total OC mass throughout the study period. Our findings showed a significant reduction in the absolute and relative contributions of tailpipe emissions to the ambient OC levels in CELA and Riverside over the time period of 2005-2015. The contribution of exhaust emissions to total OC in CELA decreased from 3.5 µg m^-3 (49%) in 2005 to 1.5 µg m^-3 (34%) in 2015, while similar trends were observed at Riverside during this period. These reductions are mainly attributed to the implementation of several federal, state, and local air quality regulations targeting tailpipe emissions in the area. The implementation of these regulations furthermore reduced the emissions of primary organic precursors of secondary aerosols, resulting in an overall decrease (although not statistically significant, P values ranging from 0.4 to 0.6) in SOA mass concentration in both locations over the study period. In contrast to the tailpipe emissions, we observed an increasing trend (by ∼4 to 14%) in the relative contribution of non-tailpipe emissions to OC over this time period at both sites. Our results demonstrated the effectiveness of air quality regulations in reducing direct tailpipe emissions in the area, but also underpinned the need to develop equally effective mitigation policies targeting non-tailpipe PM emissions.

Ambient carbon monoxide exposure and elevated risk of mortality in the glioblastoma patients: A double-cohort retrospective observational study

An increasing number of studies indicate air pollutants infiltrate into the brain. We aimed to find the association of cumulative air pollution exposure in the main body of primary brain tumor: glioblastoma (GBM). In this double-cohort, retrospective analysis study with a protocol, we compared the health effect of air pollution on the GBM patients from the SEER (Surveillance, Epidemiology, and End Results Program) in 27 U.S. counties from 10 states and GBM patients of Severance cohort of Korea. From 2000 to 2015, 10621 GBM patients of the SEER were individually evaluated for the cumulative average exposure for each pollutant, and 9444 (88.9%) mortality events were reported. From 2011 to 2018, 398 GBM patients of the Severance with the same protocol showed 259 (65.1%) mortality events. The multi-pollutant models show that the association level of risk with CO is increased in the SEER (HR 1.252; 95% CI 1.141-1.373) with an increasing linear trend of relative death rate in the spline curve. The Severance GBM data showed such a statistically significant result of the health impact of CO on GBM patients. The overall survival gain of the less exposure group against CO was 2 and 3 months in the two cohorts. Perioperative exposure to CO may increase the risk of shorter survival of GBM patients of the SEER and the Severance cohort.

The association between air pollution and cancers: controversial evidence of a systematic review

There are inconsistent reports on the association between air pollution and cancers. This systematic review was, therefore, conducted to ascertain the relationship between air pollution and some cancers. This is a systematic review study, which all articles published in this area were extracted from January 1, 1950 to December 31, 2018 from Web of Science, PubMed, Scopus, Cochrane Library, MEDLINE, EMBASE, Science Direct, Google scholar. Searching was performed independently by two search-method experts. The required data were extracted from the articles by an author-made questionnaire. Forty-eight articles were investigated. Evidence linking air pollution to some cancers is limited. Leukemia had the highest association with exposure to various air pollutants and bladder cancer had the lowest association. It is noteworthy that the specific type of pollutants in all studies was not specified. Based on the findings, the results are contradictory, and the role of air pollution in some cancers cannot be supported. Accordingly, studies are recommended to be performed at the individual level or multifactorial studies to specifically investigate the relationship between air pollution and these types of cancers. In this way, the role of air pollution in the incidence of these cancers can be determined more accurately.

Components of particulate matter air-pollution and brain tumors

BACKGROUND

Air pollution is an established carcinogen. Evidence for an association with brain tumors is, however, inconclusive. We investigated if individual particulate matter constituents were associated with brain tumor risk.

METHODS

From comprehensive national registers, we identified all (n = 12 928) brain tumor cases, diagnosed in Denmark in the period 1989-2014, and selected 22 961 controls, matched on age, sex and year of birth. We established address histories and estimated 10-year mean residential outdoor concentrations of particulate matter < 2.5 µm, primarily emitted black carbon (BC) and organic carbon (OC), and combined carbon (OC/BC), as well as secondary inorganic and organic PM air pollutants from a detailed dispersion model. We used conditional logistic regression to calculate odds ratios (OR) per inter quartile range (IQR) exposure. We adjusted for income, marital and employment status as well as area-level socio-demographic characteristics.

RESULTS

Total tumors of the brain were associated with OC/BC (OR: 1.053, 95%CI: 1.005-1.103, per IQR). The data suggested strongest associations for malignant tumors with ORs per IQR for OC/BC, BC and OC of 1.063 (95% CI: 1.007-1.123), 1.036 (95% CI: 1.006-1.067) and 1.030 (95%CI: 0.979-1.085), respectively. The results did not indicate adverse effects of other PM components.

CONCLUSIONS

This large, population based study showed associations between primary emitted carbonaceous particles and risk for malignant brain tumors. As the first of its kind, this study needs replication.

Effect of lifestyle and dietary factors in the development of brain tumors

Introduction:

A brain tumor occurs when neurons are mutated and thus abnormal cells are formed. Glioma and meningioma are the two most common types, comprising approximately 75% of all brain tumors. The incidence rate of all primary brain tumors was 15.80/100,000 person-years in females and 14.33/100,000 person-years in males. An association of higher risk of brain tumors in adults with cured meat and fruit/vegetable consumption, the primary source of dietary N-nitroso compounds, is seen. Cigarette smoking is a major source of chemical carcinogens. The present study aimed at determining the effects of lifestyle and dietary habits in the development of brain tumor.

Methods:

The study aimed at the assessment of various dietary factors, lifestyle, and occupational and personal habits in patients diagnosed with brain tumor in a rural tertiary health-care hospital, using a structured questionnaire and statistical analysis.

Results:

It was observed that – (1) people with stressful, sedentary lifestyle and wrong diet and those addicted to alcohol consumption and the habit of cigarette smoking have higher risk of brain tumors; (2) males are more prone to brain tumors; and (3) among subtypes, majority had glioblastoma and the least had meningioma and opdivoglioblastoma and according to location, majority had cerebellopontine angle tumor and the least had left thalamic glioma and multicentric glioma. Primary care to preoperative brain tumor patients should be given in terms of preventing exposure to radiations, avoiding cigarette smoking, providing healthy diet, and avoiding chronic stress and environmental pollution and postoperative patients should be taken care including avoiding infections by maintaining proper hygiene and providing healthy diet for their speedy recovery.

Conclusion:

People with stressful life condition, wrong diet, and sedentary lifestyle and those addicted to alcohol, with the habit of cigarette smoking, have higher risk of brain tumors. Males are more prone to brain tumors.

The Inducible Role of Ambient Particulate Matter in Cancer Progression via Oxidative Stress-Mediated Reactive Oxygen Species Pathways: A Recent Perception

Simple Summary

Particulate matter, especially the fine fraction PM2.5, is officially stated as carcinogenic to human. There are compelling evidences on the association between PM2.5 exposure and lung cancer, and there are also some preliminary data reporting the significant links between this fraction with non-lung cancers. The underlying mechanisms remain unclear. Further studies related to such scope are highly required. The purpose of this work is to systemically analyze recent findings concerning the relationship between PM2.5 and cancer, and to thoroughly present the oxidative stress pathways mediated by reactive oxygen species as the key mechanism for carcinogenesis induced by PM2.5. This will provide a more comprehensive and updated knowledge regarding carcinogenic capacity of PM2.5 to both clinicians and public health workers, contributing to preventive and therapeutic strategies to fight against cancer in human.

Abstract

Cancer is one of the leading causes of premature death and overall death in the world. On the other hand, fine particulate matter, which is less than 2.5 microns in aerodynamic diameter, is a global health problem due to its small diameter but high toxicity. Accumulating evidence has demonstrated the positive associations between this pollutant with both lung and non-lung cancer processes. However, the underlying mechanisms are yet to be elucidated. The present review summarizes and analyzes the most recent findings on the relationship between fine particulate matter and various types of cancer along with the oxidative stress mechanisms as its possible carcinogenic mechanisms. Also, promising antioxidant therapies against cancer induced by this poison factor are discussed.

Outdoor air pollution and cancer: An overview of the current evidence and public health recommendations

Outdoor air pollution is a major contributor to the burden of disease worldwide. Most of the global population resides in places where air pollution levels, because of emissions from industry, power generation, transportation, and domestic burning, considerably exceed the World Health Organization's health-based air-quality guidelines. Outdoor air pollution poses an urgent worldwide public health challenge because it is ubiquitous and has numerous serious adverse human health effects, including cancer. Currently, there is substantial evidence from studies of humans and experimental animals as well as mechanistic evidence to support a causal link between outdoor (ambient) air pollution, and especially particulate matter (PM) in outdoor air, with lung cancer incidence and mortality. It is estimated that hundreds of thousands of lung cancer deaths annually worldwide are attributable to PM air pollution. Epidemiological evidence on outdoor air pollution and the risk of other types of cancer, such as bladder cancer or breast cancer, is more limited. Outdoor air pollution may also be associated with poorer cancer survival, although further research is needed. This report presents an overview of outdoor air pollutants, sources, and global levels, as well as a description of epidemiological evidence linking outdoor air pollution with cancer incidence and mortality. Biological mechanisms of air pollution-derived carcinogenesis are also described. This report concludes by summarizing public health/policy recommendations, including multilevel interventions aimed at individual, community, and regional scales. Specific roles for medical and health care communities with regard to prevention and advocacy and recommendations for further research are also described.

Intracranial tumors of the central nervous system and air pollution - a nationwide case-control study from Denmark

BACKGROUND

Inconclusive evidence has suggested a possible link between air pollution and central nervous system (CNS) tumors. We investigated a range of air pollutants in relation to types of CNS tumors.

METHODS

We identified all (n = 21,057) intracranial tumors in brain, meninges and cranial nerves diagnosed in Denmark between 1989 and 2014 and matched controls on age, sex and year of birth. We established personal 10-year mean residential outdoor exposure to particulate matter < 2.5 μm (PM_2.5), nitrous oxides (NO_X), primary emitted black carbon (BC) and ozone. We used conditional logistic regression to calculate odds ratios (OR) linearly (per interquartile range (IQR)) and categorically. We accounted for personal income, employment, marital status, use of medication as well as socio-demographic conditions at area level.

RESULTS

Malignant tumors of the intracranial CNS was associated with BC (OR: 1.034, 95%CI: 1.005-1.065 per IQR. For NO_x the OR per IQR was 1.026 (95%CI: 0.998-1.056). For malignant non-glioma tumors of the brain we found associations with PM_2.5 (OR: 1.267, 95%CI: 1.053-1.524 per IQR), BC (OR: 1.049, 95%CI: 0.996-1.106) and NO_x (OR: 1.051, 95% CI: 0.996-1.110).

CONCLUSION

Our results suggest that air pollution is associated with malignant intracranial CNS tumors and malignant non-glioma of the brain. However, additional studies are needed.

High particulate matter 2.5 levels and ambient temperature are associated with acute lung edema in patients with nondialysis Stage 5 chronic kidney disease

BACKGROUND

Numerous studies have shown that exposure to air pollution, especially particulate matter (PM) with a diameter <2.5 μm (PM2.5), was associated with various diseases. We tried to determine the impact of PM2.5 and other weather factors on acute lung edema in patients with Stage 5 nondialysis chronic kidney disease (CKD Stage 5-ND).

METHODS

In total, 317 CKD Stage 5-ND (estimated glomerular filtration rate 6.79 ± 4.56 mL/min) patients residing in central Taiwan who developed acute lung edema and initiated long-term dialysis were included in this case-crossover study. Pearson's correlation test was used to examine the relationship of acute lung edema cases with PM2.5 levels and ambient temperature separately.

RESULTS

The average PM2.5 level within the 7-day period correlated with acute lung edema incidence in the fall [adjusted odds ratio (OR) 3.23, P = 0.047] and winter (adjusted OR 1.99, P < 0.001). In winter, even a 3-day exposure to PM2.5 was associated with increased risk (adjusted OR 1.55, P < 0.001). The average temperatures within 3 days in spring and summer were correlated positively with the risk (adjusted OR 2.77 P < 0.001 and adjusted OR 2.72, P < 0.001, respectively). In the fall and winter, temperatures were correlated negatively with the risk (adjusted OR 0.36, P < 0.001 and adjusted OR 0.54, P < 0.001, respectively).

CONCLUSIONS

A high PM2.5 level was associated with an increased risk of acute lung edema. High ambient temperature in hot seasons and low ambient temperature in cold seasons were also associated with increased risk. It is essential to educate these patients to avoid areas with severe air pollution and extreme ambient temperature.

Birth seasonality of childhood central nervous system tumors: Analysis of primary data from 16 Southern-Eastern European population-based registries

Season of birth, a surrogate of seasonal variation of environmental exposures, has been associated with increased risk of several cancers. In the context of a Southern-Eastern Europe (SEE) consortium, we explored the potential association of birth seasonality with childhood (0-14 years) central nervous system (CNS) tumors. Primary CNS tumor cases (n = 6,014) were retrieved from 16 population-based SEE registries (1983-2015). Poisson regression and meta-analyses on birth season were performed in nine countries with available live birth data (n = 4,987). Subanalyses by birth month, age, gender and principal histology were also conducted. Children born during winter were at a slightly increased risk of developing a CNS tumor overall [incidence rate ratio (IRR): 1.06, 95% confidence intervals (CI): 0.99-1.14], and of embryonal histology specifically (IRR: 1.13, 95% CI: 1.01-1.27). The winter peak of embryonal tumors was higher among boys (IRR: 1.24, 95% CI: 1.05-1.46), especially during the first 4 years of life (IRR: 1.33, 95% CI: 1.03-1.71). In contrast, boys <5 years born during summer seemed to be at a lower risk of embryonal tumors (IRR: 0.73, 95% CI: 0.54-0.99). A clustering of astrocytomas was also found among girls (0-14 years) born during spring (IRR: 1.23, 95% CI: 1.03-1.46). Although the present exploratory results are by no means definitive, they provide some indications for age-, gender- and histology-related seasonal variations of CNS tumors. Expansion of registration and linkage with cytogenetic reports could refine if birth seasonality is causally associated with CNS tumors and shed light into the complex pathophysiology of this lethal disease.

Association Between Outdoor Air Pollution and Risk of Malignant and Benign Brain Tumors: The Multiethnic Cohort Study

Background

There are increasing concerns about the potential impact of air pollution on chronic brain inflammation and microglia cell activation, but evidence of its carcinogenic effects is limited.

Methods

We used kriging interpolation and land use regression models to estimate long-term air pollutant exposures of oxides of nitrogen (NO_x, NO₂), kriging interpolation for ozone (O₃), carbon monoxide, and particulate matter (PM_2.5, PM₁₀), and nearest monitoring station measurements for benzene for 103 308 men and women from the Multiethnic Cohort, residing largely in Los Angeles County from recruitment (1993–1996) through 2013. We used Cox proportional hazards models to examine the associations between time-varying pollutants and risk of malignant brain cancer (94 men, 116 women) and meningioma (130 men, 425 women) with adjustment for sex, race and ethnicity, neighborhood socioeconomic status, smoking, occupation, and other covariates. Stratified analyses were conducted by sex and race and ethnicity.

Results

Brain cancer risk in men increased in association with exposure to benzene (hazard ratio [HR] = 3.52, 95% confidence interval [CI] = 1.55 to 7.55) and PM₁₀ (HR = 1.80, 95% CI = 1.00 to 3.23). Stronger associations with PM₁₀ (HR = 3.02, 95% CI = 1.26 to 7.23), O₃ (HR = 2.93, 95% CI = 1.09 to 7.88), and benzene (HR = 4.06, 95% CI = 1.17 to 18.2) were observed among Latino men. Air pollution was unrelated to risk of meningioma except that O₃ exposure was associated with risk in men (HR = 1.77, 95% CI = 1.02 to 3.06). Brain cancer risk in women was unrelated to air pollution exposures.

Conclusions

Confirmation of these sex differences in air pollution–brain cancer associations and the stronger findings in Latino men in additional diverse populations is warranted.

Air pollution and health: Evidence from epidemiological studies and population impact

Outdoor air pollution —in particular particulate matter, nitrogen dioxide and ozone— can exert its effects on health after acute (short-term) and chronic (long-term) exposures. Short-term exposures increase the probability of the onset of acute diseases within a few days, such as myocardial infarction or stroke, or even death in the case of susceptible individuals. Long-term exposures are associated with decreased survival and incidence of several non-communicable diseases, including cardiorespiratory conditions and lung cancer. In Europe, the large ESCAPE project (European Study of Cohorts for Air Pollution Effects — www.escapeproject.eu) evaluated the chronic effects of air pollution in the cohorts of adult subjects. The results of ESCAPE show an association between chronic exposure to air pollutants and natural mortality, cardiovascular events, lung, brain, breast and digestive tract cancer. The recent joint statement of the European Respiratory Society and the American Respiratory Society clarifies the wide spectrum of adverse effects of pollution, including “new” diseases such as neurological and metabolic syndrome previously not studied. The estimates by the Global Burden of Disease provide nowadays indications that air pollution causes illness and mortality, just after diet, smoking, hypertension and diabetes: 4.2 million premature deaths a year worldwide. Ischemic heart disease, stroke, chronic obstructive pulmonary disease, acute lower respiratory infections are the main conditions associated with air-pollution–related mortality.

Long-term exposure to air pollution and the risk of non-lung cancer: a meta-analysis of observational studies

AIMS

Several meta-analyses of observational studies report a long-term correlation between air pollution and the risk of cancer, particularly lung carcinoma. The aim of this study was to review and quantify evidence for an association between air pollution and the risk of developing non-lung cancers.

METHODS

We searched PubMed, EMBASE, Cochrane Library, and the reference lists of the included studies as well as those recorded in previous meta-analyses conducted before January 2019. A random-effects model was used to derive overall risk estimates per pollutant.

RESULTS

A total of 20 studies, including 5 case-control and 15 prospective cohort studies, were used in the final analysis. The risk of developing non-lung cancer was 1.09 (95% confidence interval (CI): 1.01-1.18, I² = 72.9%) per NO₂ increases of 10 µg/m³. There was also a significant association between exposure to PM_2.5 and PM₁₀ and the risk of non-lung cancer when the male and female populations were combined (pooled odds ratio/relative risk (OR/RR) = 1.22, 95% CI: 1.11-1.34; I² = 0.0% and pooled OR/RR = 1.26, 95% CI: 1.05-1.52; I² = 43.9%, respectively). Regarding the type of cancer, significant harmful effects of PM_2.5 were observed for liver cancer populations (pooled OR/RR = 1.21, 95% CI: 1.10-1.32; I² = 0.0%). Different types of cancer were positively associated with the incidence of non-lung cancer and PM₁₀ in the random-effect meta-regression analysis.

CONCLUSIONS

Long-term exposure to air pollutants appears to be associated with an increased risk of non-lung cancer. Care should be taken in interpretation, because the results for specific cancers were restricted.