Effects of air pollution on the nervous system and its possible role in neurodevelopmental and neurodegenerative disorders

Acute effects of ambient nitrogen dioxide exposure on serum biomarkers of nervous system damage in healthy older adults

Ambient nitrogen dioxide (NO₂)-induced adverse health effects have been studied, but documented evidence on neural systems is limited. This study aimed to determine the acute effect of NO₂ exposure on nervous system damage biomarker levels in healthy older adults. Five rounds of follow-up among 34 healthy retired people were scheduled from December 2018 to April 2019 in Xinxiang, China. The real-time NO₂ concentrations were measured using a fixed site monitor. Serum samples were acquired during each round to measure nervous system damage biomarker levels: brain-derived neurotrophic factor (BDNF), neurofilament light chain (NfL), neuron-specific enolase (NSE), protein gene product 9.5 (PGP9.5), and S100 calcium-binding protein B (S100B). A linear mixed-effect model was incorporated to analyze the association between short-term NO₂ exposure and serum concentrations of the above-mentioned biomarkers. Stratification analysis based on sex, educational attainment, glutathione S-transferase theta 1 gene (GSTT1) polymorphism, and physical activity intensity was conducted to explore their potential modification effect. The NO₂ concentration ranged from 34.7 to 59.0 µg/m³ during the study period. Acute exposure to ambient NO₂ was significantly associated with elevated serum levels of NfL, PGP9.5, and BDNF. In response to a 10 µg/m³ increase in NO₂ concentration, NfL and PGP9.5 levels increased by 76 % (95 % confidence interval [CI]: 12-140 %) and 54 % (95 % CI: 1-107 %) on the lag0 day, respectively, while BDNF levels increased by 49 % (95 % CI: 2-96 %) at lag4 day. The estimated effect of NO₂ on NSE levels in GSTT1-sufficient participants was significantly higher than that in GSTT1-null participants. Intriguingly, the estimation of NO₂ on PGP9.5 levels in females was significantly higher than that in males. Most two-pollutant models showed robust results, except for O₃, which might have had confounding effects on NO₂-induced BDNF stimulation. In summary, acute exposure to NO₂ was associated with increased levels of serum nervous system damage biomarker levels including NFL, PGP9.5, and BDNF. The present study provided insights into NO₂ exposure-induced adverse neural effects.

Ambient Benzo[a]pyrene's Effect on Kinetic Modulation of Amyloid Beta Peptide Aggregation: A Tentative Association between Ultrafine Particulate Matter and Alzheimer's Disease

Long-time exposure to ambient ultrafine particles is associated with an increased risk of neurodegenerative diseases such as Alzheimer's disease (AD), which is triggered by the aggregation of Aβ peptide monomers into toxic oligomers. Among different ultrafine air pollutants, polycyclic aromatic hydrocarbons (PAHs) are known to have a negative neural impact; however, the impact mechanism remains obscure. We herein examined the effect of Benzo[a]Pyrene (B[a]P), one of the typical PAHs on Aβ₄₂ oligomerization using all-atom molecular dynamics simulations. In particular, the simulations were performed using four molecules of Aβ₄₂ in the presence of 5.00 mM, 12.5 mM, and 50.0 mM of B[a]P. The results revealed strong hydrophobic interactions between Aβ₄₂ peptides and B[a]P, which in turn resulted in increased interpeptide electrostatic interactions. Furthermore, 5.00 mM of B[a]P accelerated the kinetics of the formation of peptide tetramer by 30%, and stabilized C-terminus in Aβ₄₂ peptides, suggesting consequent progression of AD in the presence of 5.00 mM B[a]P. In contrast, 12.5 mM and 50.0 mM of B[a]P decreased interpeptide interactions and H-bonding due to the aggregation of numerous B[a]P clusters with the peptides, suppressing oligomerization kinetics of Aβ₄₂ peptides by 13% and 167%, respectively. While the study elucidates the effect of small environmental hydrophobic molecules on the formation of Aβ oligomers, the impact of ambient ultrafine particles on AD in the complex composition of the environmental realm requires further systematic delving into the field.

Association between Exposure to Particulate Matter Air Pollution during Early Childhood and Risk of Attention-Deficit/Hyperactivity Disorder in Taiwan

(1) Background: Recently, a growing number of studies have provided evidence to suggest a strong correlation between air pollution exposure and attention-deficit/hyperactivity disorder (ADHD). In this study, we assessed the relationship between early-life exposure to particulate matter (PM)₁₀, PM₂.₅, and ADHD; (2) Methods: The National Health Insurance Research Database (NHIRD) contains the medical records, drug information, inspection data, etc., of the people of Taiwan, and, thus, could serve as an important research resource. Air pollution data were based on daily data from the Environmental Protection Administration Executive Yuan, R.O.C. (Taiwan). These included particulate matter (PM_2.5 and PM₁₀). The two databases were merged according to the living area of the insured and the location of the air quality monitoring station; (3) Results: The highest levels of air pollutants, including PM_2.5 (adjusted hazard ratio (aHR) = 1.79; 95% confidence interval (CI) = 1.58-2.02) and PM₁₀ (aHR = 1.53; 95% CI = 1.37-1.70), had a significantly higher risk of ADHD; (4) Conclusions: As such, measures for air quality control that meet the WHO air quality guidelines should be strictly and uniformly implemented by Taiwanese government authorities.

Mitigating the impact of air pollution on dementia and brain health: Setting the policy agenda

BACKGROUND

Emerging research suggests exposure to high levels of air pollution at critical points in the life-course is detrimental to brain health, including cognitive decline and dementia. Social determinants play a significant role, including socio-economic deprivation, environmental factors and heightened health and social inequalities. Policies have been proposed more generally, but their benefits for brain health have yet to be fully explored.

OBJECTIVE AND METHODS

Over the course of two years, we worked as a consortium of 20+ academics in a participatory and consensus method to develop the first policy agenda for mitigating air pollution's impact on brain health and dementia, including an umbrella review and engaging 11 stakeholder organisations.

RESULTS

We identified three policy domains and 14 priority areas. Research and Funding included: (1) embracing a complexities of place approach that (2) highlights vulnerable populations; (3) details the impact of ambient PM_2.5 on brain health, including current and historical high-resolution exposure models; (4) emphasises the importance of indoor air pollution; (5) catalogues the multiple pathways to disease for brain health and dementia, including those most at risk; (6) embraces a life course perspective; and (7) radically rethinks funding. Education and Awareness included: (8) making this unrecognised public health issue known; (9) developing educational products; (10) attaching air pollution and brain health to existing strategies and campaigns; and (11) providing publicly available monitoring, assessment and screening tools. Policy Evaluation included: (12) conducting complex systems evaluation; (13) engaging in co-production; and (14) evaluating air quality policies for their brain health benefits.

CONCLUSION

Given the pressing issues of brain health, dementia and air pollution, setting a policy agenda is crucial. Policy needs to be matched by scientific evidence and appropriate guidelines, including bespoke strategies to optimise impact and mitigate unintended consequences. The agenda provided here is the first step toward such a plan.

Exposure to a real traffic environment impairs brain cognition in aged mice

Traffic-related air pollution (TRAP) has been a common public health problem, which is associated with central nervous system dysfunction according to large-scale epidemiological studies. Current studies are mostly limited to artificial laboratory exposure environments and specific genetic mechanisms remain unclear. Therefore, we chose a real-world transportation environment to expose aged mice, transporting them from the laboratory to a 1-m-high dry platform inside the campus and tunnel, and the mice were exposed daily from 7 a.m. to 7 p.m. for 2, 4 and 12 weeks respectively. Compared with the control group (in campus), the memory function of mice in the experimental group (in tunnel) was significantly impaired in the Morris water maze test. TRAP exposure increased the number of activated microglia in the hippocampal DG, CA1, CA3 regions and dorsolateral prefrontal cortex (dPFC). And neuroinflammation and oxidative stress levels were up-regulated in both hippocampus and dPFC of aged mice. By screening the risk genes of Alzheimer's disease, we found the mRNA and protein levels of ABCA7 were down-regulated and those of PYK2 were up-regulated. The DNA methylation ratios increased in four CpG sites of abca7 promoter region and decreased in one CpG site of pyk2 promoter region, which were consistent with the altered expression of ABCA7 and PYK2. In conclusion, exposure to the real traffic environment impaired memory function and enhanced neuroinflammation and oxidative stress responses, which could be relevant to the altered expression and DNA methylation levels of ABCA7 and PYK2. Our work provides a new and promising understanding of the pathological mechanisms of cognitive impairment caused by traffic-related air pollution.

Air pollution, depressive and anxiety disorders, and brain effects: A systematic review

Accumulating data suggest that air pollution increases the risk of internalizing psychopathology, including anxiety and depressive disorders. Moreover, the link between air pollution and poor mental health may relate to neurostructural and neurofunctional changes. We systematically reviewed the MEDLINE database in September 2021 for original articles reporting effects of air pollution on 1) internalizing symptoms and behaviors (anxiety or depression) and 2) frontolimbic brain regions (i.e., hippocampus, amygdala, prefrontal cortex). One hundred and eleven articles on mental health (76% human, 24% animals) and 92 on brain structure and function (11% human, 86% animals) were identified. For literature search 1, the most common pollutants examined were PM2.5 (64.9%), NO2 (37.8%), and PM10 (33.3%). For literature search 2, the most common pollutants examined were PM2.5 (32.6%), O3 (26.1%) and Diesel Exhaust Particles (DEP) (26.1%). The majority of studies (73%) reported higher internalizing symptoms and behaviors with higher air pollution exposure. Air pollution was consistently associated (95% of articles reported significant findings) with neurostructural and neurofunctional effects (e.g., increased inflammation and oxidative stress, changes to neurotransmitters and neuromodulators and their metabolites) within multiple brain regions (24% of articles), or within the hippocampus (66%), PFC (7%), and amygdala (1%). For both literature searches, the most studied exposure time frames were adulthood (48% and 59% for literature searches 1 and 2, respectively) and the prenatal period (26% and 27% for literature searches 1 and 2, respectively). Forty-three percent and 29% of studies assessed more than one exposure window in literature search 1 and 2, respectively. The extant literature suggests that air pollution is associated with increased depressive and anxiety symptoms and behaviors, and alterations in brain regions implicated in risk of psychopathology. However, there are several gaps in the literature, including: limited studies examining the neural consequences of air pollution in humans. Further, a comprehensive developmental approach is needed to examine windows of susceptibility to exposure and track the emergence of psychopathology following air pollution exposure.

Air Pollution: Possible Interaction between the Immune and Nervous System?

Exposure to environmental pollutants is a serious and common public health concern associated with growing morbidity and mortality worldwide, as well as economic burden. In recent years, the toxic effects associated with air pollution have been intensively studied, with a particular focus on the lung and cardiovascular system, mainly associated with particulate matter exposure. However, epidemiological and mechanistic studies suggest that air pollution can also influence skin integrity and may have a significant adverse impact on the immune and nervous system. Air pollution exposure already starts in utero before birth, potentially causing delayed chronic diseases arising later in life. There are, indeed, time windows during the life of individuals who are more susceptible to air pollution exposure, which may result in more severe outcomes. In this review paper, we provide an overview of findings that have established the effects of air pollutants on the immune and nervous system, and speculate on the possible interaction between them, based on mechanistic data.

Different components of air pollutants and neurological disorders

The harmful effects of air pollution can cause various diseases. Most research on the hazards of air pollution focuses on lung and cardiovascular diseases. In contrast, the impact of air pollution on neurological disorders is not widely recognized. Air pollution can cause various neurological conditions and diseases, such as neural inflammation, neurodegeneration, and cerebrovascular barrier disorder; however, the mechanisms underlying the neurological diseases induced by various components of air pollutants remain unclear. The present paper summarizes the effects of different components of air pollutants, including particulate matter, ozone, sulfur oxides, carbon oxides, nitrogen oxides, and heavy metals, on the nervous system and describes the impact of various air pollutants on neurological disorders, providing ideas for follow-up research.

Neuroinflammation and Neurodegeneration of the Central Nervous System from Air Pollutants: A Scoping Review

In this scoping review, we provide a selective mapping of the global literature on the effects of air pollution on the life-span development of the central nervous system. Our synthesis first defines developmental neurotoxicants and the model effects of particulate matter. We then discuss air pollution as a test bench for neurotoxicants, including animal models, the framework of systemic inflammation in all affected organs of the body, and the cascade effects on the developing brain, with the most prevalent neurological structural and functional outcomes. Specifically, we focus on evidence on magnetic resonance imaging and neurodegenerative diseases, and the links between neuronal apoptosis and inflammation. There is evidence of a developmental continuity of outcomes and effects that can be observed from utero to aging due to severe or significant exposure to neurotoxicants. These substances alter the normal trajectory of neurological aging in a propulsive way towards a significantly higher rate of acceleration than what is expected if our atmosphere were less polluted. The major aggravating role of this neurodegenerative process is linked with the complex action of neuroinflammation. However, most recent evidence learned from research on the effects of COVID-19 lockdowns around the world suggests that a short-term drastic improvement in the air we breathe is still possible. Moreover, the study of mitohormesis and vitagenes is an emerging area of research interest in anti-inflammatory and antidegenerative therapeutics, which may have enormous promise in combatting the deleterious effects of air pollution through pharmacological and dietary interventions.

Paraquat exposure induces Parkinsonism by altering lipid profile and evoking neuroinflammation in the midbrain

Paraquat (PQ) is the most widely used herbicide in the world and a well-known potent neurotoxin for humans. PQ exposure has been linked to increase the risk of Parkinson's disease (PD). However, the mechanism underlying its neurotoxic effects in PD pathogenesis is unclear. In our present study, C57BL/6J mice treated with PQ manifested severe motor deficits indicated by the significant reductions in suspension score, latency to fall from rotarod, and grip strength at 8 weeks after PQ exposure. Pathological hallmarks of Parkinsonism in the midbrain such as dopaminergic neuron loss, increased α-synuclein protein, and dysregulated PD-related genes were observed. Non-targeted lipidome analysis demonstrated that PQ exposure alters lipid profile and abundance, increases pro-inflammatory lipids.27 significantly altered subclasses of lipids belonged to 6 different lipid categories. Glycerophospholipids, sphingolipids, and glycerides were the most abundant lipids. Abundance of pro-inflammatory lipids such as Cer, LPC, LPS, and LPI was significantly increased in the midbrain. mRNA expressions of genes regulating ceramide biosynthesis in the midbrain were markedly up-regulated. Moreover, PQ exposure increased serum pro-inflammatory cytokines and provoked neuroinflammation in the midbrain. Pro-inflammatory lipids and cytokines in the midbrain were positively correlated with motor deficits. PQ poisoning in humans significantly also elevated serum pro-inflammatory cytokines and induced an intense systemic inflammation. In summary, we presented initial investigations of PQ induced molecular events related to the PD pathogenesis, capturing aspects of disturbed lipid metabolism, neuroinflammation, impairment of dopaminergic neurons in the midbrain, and an intense systemic inflammation. These neurotoxic effects of PQ exposure may mechanistically contribute to the pathogenesis of PQ induced Parkinsonism. Results of this study also strongly support the hypothesis that ever-increasing prevalence of Parkinson's disease is etiologically linked to the health risk of exposure to neurotoxic environmental pollutants.

Genomic Basis for Individual Differences in Susceptibility to the Neurotoxic Effects of Diesel Exhaust

Air pollution is a known environmental health hazard. A major source of air pollution includes diesel exhaust (DE). Initially, research on DE focused on respiratory morbidities; however, more recently, exposures to DE have been associated with neurological developmental disorders and neurodegeneration. In this study, we investigated the effects of sub-chronic inhalation exposure to DE on neuroinflammatory markers in two inbred mouse strains and both sexes, including whole transcriptome examination of the medial prefrontal cortex. We exposed aged male and female C57BL/6J (B6) and DBA/2J (D2) mice to DE, which was cooled and diluted with HEPA-filtered compressed air for 2 h per day, 5 days a week, for 4 weeks. Control animals were exposed to HEPA-filtered air on the same schedule as DE-exposed animals. The prefrontal cortex was harvested and analyzed for proinflammatory cytokine gene expression (Il1β, Il6, Tnfα) and transcriptome-wide response by RNA-seq. We observed differential cytokine gene expression between strains and sexes in the DE-exposed vs. control-exposed groups for Il1β, Tnfα, and Il6. For RNA-seq, we identified 150 differentially expressed genes between air and DE treatment related to natural killer cell-mediated cytotoxicity per Kyoto Encyclopedia of Genes and Genomes pathways. Overall, our data show differential strain-related effects of DE on neuroinflammation and neurotoxicity and demonstrate that B6 are more susceptible than D2 to gene expression changes due to DE exposures than D2. These results are important because B6 mice are often used as the default mouse model for DE studies and strain-related effects of DE neurotoxicity warrant expanded studies.

Maternal PM2.5 exposure during gestation and offspring neurodevelopment: Findings from a prospective birth cohort study

Emerging data have suggested the potential role of prenatal PM_2.5 exposure as a neurotoxin for offspring. However, the existing results are equivocal, and no study has examined the effects of complex chemical constituents of the particular matter on offspring neurodevelopment. Therefore, in a prospective birth cohort study conducted in Jiangsu, China, we aimed to investigate the association between prenatal exposure to PM_2.5 and the neurodevelopment in infants, and further assess the effects of specific chemical constituents of PM_2.5. A total of 1531 children who had available data on daily prenatal PM_2.5 exposure and completed assessment on neurodevelopment at 1 year old were enrolled. We used the high-performance machine-learning model to estimate daily PM_2.5 exposure concentrations at 1 km × 1 km spatial resolution. The combined geospatial-statistical model was applied to evaluate average concentrations of six chemical constituents [organic matter (OM), black carbon (BC), sulfate (SO₄^2-), nitrate (NO₃^-), ammonium (NH₄⁺), and soil dust (Dust)]. The neurodevelopment of children was assessed using Bayley-III Screening Test. After adjusting for confounding factors, the risk of non-optimal gross motor development increased by 31 % for every 10 μg/m³ increase in average PM_2.5 exposure during gestation (aRR: 1.31; 95 % CI: 1.04, 1.64). Further analysis of PM_2.5 constituents showed that prenatally exposed to high SO₄^2- was associated with the risk of non-optimal gross motor development (aRR: 1.40; 95 % CI: 1.08, 1.81). Null associations were observed for the rest four neurodevelopment domains. Collectively, our study suggested that prenatal exposure to PM_2.5, particularly with high SO₄^2- concentration, was associated with children's non-optimal gross motor development at 1 year old. The short- and long-term influences of perinatal PM_2.5 exposure on children's neurodevelopment warrant further investigation.

Risk of functional disability associated with solid fuel use and population impact of reducing indoor air pollution in China: A national cohort study

Background

In China, numerous people still rely on solid fuel for household use. To date, the association between household solid fuel use and functional disability, and what benefit reducing household solid fuel usage could bring at the population level to China remain unclear.

Method

Data were from the China Health and Retirement Longitudinal Study. Household fuel was classified as clean or solid for cooking or heating. Functional disability was defined as difficulties in any item of activities of daily living (ADL) or instrumental activities of daily living (IADL). The associations of household fuel use in 2011 and its transitions between 2011 and 2013 with subsequent ADL or IADL disability were assessed with Cox proportional-hazards models. The number of events prevented in a population (NEPP) was generated to estimate how many functionally disabled patients could be prevented by reducing solid fuel usage.

Results

A total of 6,216 and 9,716 participants without prior ADL or IADL disability in 2011 were included. Solid (vs. clean) fuel users were more likely to develop ADL and IADL disability, with hazard ratios (HRs) and 95% confidence intervals (CIs) of 1.37 (1.28~1.45) and 1.38 (1.31~1.46) for using both solid cooking and heating fuel. Furthermore, participants that switched heating fuel from solid to clean (vs. keep solid) were about 20% less likely to develop functional disability. Cooking fuel use switching from solid to clean (vs. keep solid) was also negatively associated with IADL disability (HR = 0.84, 95% CI 0.74~0.96). Over the next 7 years, raising clean fuel usage to 80% could prevent about 4.9 million ADL disability and 2.6 million IADL disability among Chinese aged 45 and older.

Conclusion

Household solid fuel use was a risk factor for functional disability. Reducing solid fuel usage could help reduce the burden of functional disability in the current aging society of China.

Prenatal fine particulate matter exposure associated with placental small extracellular vesicle derived microRNA and child neurodevelopmental delays

BACKGROUND AND AIMS

Prenatal fine particulate matter (PM_2.5) exposure has been linked to adverse neurodevelopment. However, epidemiological evidence remains inconclusive and little information about the effects of various PM_2.5 components on child neurodevelopment is currently known. The underlying mechanism was also not elucidated. The study aimed to evaluate the effects of PM_2.5 and components exposure on child neurodevelopmental delays and the role of placental small extracellular vesicles (sEVs)-derived miRNAs in the associations.

METHODS

We included 267 mother-child pairs in this analysis. Prenatal PM_2.5 and components (i.e. elements, water-soluble ions, and PAHs) exposure during three trimesters were monitored through personal PM_2.5 sampling. Child neurodevelopment at 2, 6, and 12 months old were evaluated by Ages and Stages Questionnaire (ASQ). We isolated sEVs from placental tissue to analyze the change of sEVs-derived miRNAs in response to PM_2.5. Associations between the PM_2.5-associated miRNAs and child neurodevelopment were evaluated using multivariate linear regression models.

RESULTS

The PM_2.5 exposure levels in the three trimesters range from 2.51 to 185.21 μg/m³. Prenatal PM_2.5 and the components of Pb, Al, V and Ti exposure in the second and third trimester were related to decreased ASQ scores communication, problem-solving and personal-social domains in children aged 2 or 6 months. RNA sequencing identified fifteen differentially expressed miRNAs. The miR-101-3p and miR-520d-5p were negatively associated with PM_2.5 and Pb component. miR-320a-3p expression was positively associated with PM_2.5 and V component. Meanwhile, the miR-320a-3p was associated with decreased ASQ scores, as reflected by ASQ-T (β: -2.154, 95 % CI: -4.313, -0.516) and problem-solving domain (β: -0.605, 95 % CI: -1.111, -0.099) in children aged 6 months.

CONCLUSION

Prenatal exposure to PM_2.5 and its Pb, Al, V & Ti component were associated with infant neurodevelopmental delays. The placenta sEVs derived miRNAs, especially miR-320a-3p, might contribute to an increased risk of neurodevelopmental delays.

Are persistent aircraft trails a threat to the environment and health?

According to most scientific studies, media and governments, the white trails that can be seen behind aircraft in flight, corresponding to condensation mixed with engine particulate emissions, only persist under specific atmospheric conditions. They are called condensation trails, and cirrus contrails when they remain for hours to reach several kilometers wide. The fact that they have gradually filled the skies over the last twenty years would be due to the increase in air traffic. However, other official documents link these persistent trails to a weather modification technology called solar geoengineering by stratospheric aerosol injection (SAI). These sprays would be mainly composed of metallic particles (Al, Ba, Sr, Fe, nanoparticles) and sulfur, which would considerably increase air, soil and water pollution. Many of the current environmental and health problems are consistent with those described in the literature on solar geoengineering by SAI if this method was employed. For example, metal particles used are well known environmental contaminants, ozone layer depletion, cardiorespiratory diseases, neurodegenerative diseases, sunburn. The observations (whiter skies, less solar power) also correspond to the same risks as those described in the solar geoengineering works. Patents show that this weather modification technology has been known and mastered for a long time. In addition, some scientific papers as well as policy documents suggest that solar geoengineering by SAI has been used for many years. The amount of official information presented in this review is intended to open new ways of investigation, free of conflicts of interest, about the growing global pollution of persistent aircraft trails and their possible links with solar geoengineering by SAI.

Protection against Paraquat-Induced Oxidative Stress by Curcuma longa Extract-Loaded Polymeric Nanoparticles in Zebrafish Embryos

The link between oxidative stress and environmental factors plays an important role in chronic degenerative diseases; therefore, exogenous antioxidants could be an effective alternative to combat disease progression and/or most significant symptoms. Curcuma longa L. (CL), commonly known as turmeric, is mostly composed of curcumin, a multivalent molecule described as having antioxidant, anti-inflammatory and neuroprotective properties. Poor chemical stability and low oral bioavailability and, consequently, poor absorption, rapid metabolism, and limited tissue distribution are major restrictions to its applicability. The advent of nanotechnology, by combining nanosacale with multi-functionality and bioavailability improvement, offers an opportunity to overcome these limitations. Therefore, in this work, poly-Ɛ-caprolactone (PCL) nanoparticles were developed to incorporate the methanolic extract of CL, and their bioactivity was assessed in comparison to free or encapsulated curcumin. Their toxicity was evaluated using zebrafish embryos by applying the Fish Embryo Acute Toxicity test, following recommended OECD guidelines. The protective effect against paraquat-induced oxidative damage of CL extract, free or encapsulated in PCL nanoparticles, was evaluated. This herbicide is known to cause oxidative damage and greatly affect neuromotor functions. The overall results indicate that CL-loaded PCL nanoparticles have an interesting protective capacity against paraquat-induced damage, particularly in neuromuscular development that goes well beyond that of CL extract itself and other known antioxidants.

Microplastic: A particulate matter(PM) generated by deterioration of building materials

Particulate matter (PM), an inhalable material, is generated from various sources, including building materials. To maintain indoor air quality, it is necessary to analyze harmful substances and establish a method for their remediation. The purpose of this study is to identify the particles generated during the deterioration of building materials and analyze the composition of fine dust particles with respect to the degree of deterioration. The concentration of particles generated was analyzed using an SPS30 PM sensor in the built chamber. PM10 and PM2.5 levels of the maximum of 41.95 mg/m³ and 20.63 mg/m³, respectively, were generated from the tested building materials. The components of the collected PM were carbon, hydrogen, and silicon, among others, which are high-molecular-weight compounds. Particles of size 2.5 µm or less were detected, and the possibility of generating nanoplastics was investigated.

Exposure to road traffic noise and behavioral problems in Chinese schoolchildren: A cross-sectional study

BACKGROUND

Transportation noise is second only to air pollution as an environmental contributor to adverse health outcomes in Western countries. However, no studies investigated the association between road traffic noise and behavioral problems among schoolchildren in China.

OBJECTIVE

To investigate the association between exposure to road traffic noise at home and behavioral problems in Chinese schoolchildren.

METHODS

From January to June 2017, we screened 3236 children aged 7-13 years in Guangzhou (Guangdong, China) from the first investigation of an ongoing school-based cohort study with complete information on behavioral problems and residential geolocation. Residential road traffic noise exposure levels were assessed using a validated modeling method in different periods of the day, including daytime (L_day), nighttime (L_night), and weighted 24-hr (L_dn). The annual mean concentration of nitrogen dioxide was also modeled in our study. Behavioral problems were assessed by the parent-rated Strengths and Difficulties Questionnaire (SDQ). Generalized linear mixed models were utilized to estimate the associations between road traffic noise and behavioral problems.

RESULTS

In the main adjusted model, a 10-dB increase in L_dn was associated with 0.33 (95% CI: 0.08, 0.59), 0.08 (95% CI: -0.01, 0.17), and 0.09 (95% CI: 0.01, 0.16) increases in three subscales score for total difficulties score, emotional problems, and conduct problems, respectively. The same increase in L_dn was also associated with the abnormal total difficulties score (OR = 1.25, 95%CI: 1.01, 1.55), emotional problems (OR = 1.19, 95%CI: 0.98, 1.44), and conduct problems (OR = 1.28, 95%CI:1.02, 1.63). Externalising behavior appears more susceptible to traffic noise than internalising behavior. NO₂ had a small impact on the associations between L_dn and behavioral problems. Our estimates were generally robust in several sensitivity analyses.

CONCLUSION

Residential road traffic noise exposure might be related to increased behavioral problems in Chinese schoolchildren, such as emotional symptoms and conduct problems.

The complex relationship of air pollution and neighborhood socioeconomic status and their association with cognitive decline

BACKGROUND

Air pollution and neighborhood socioeconomic status (nSES) have been shown to affect cognitive decline in older adults. In previous studies, nSES acts as both a confounder and an effect modifier between air pollution and cognitive decline.

OBJECTIVES

This study aims to examine the individual and joint effects of air pollution and nSES on cognitive decline on adults 50 years and older in Metro Atlanta, USA.

METHODS

Perceived memory and cognitive decline was assessed in 11,897 participants aged 50+ years from the Emory Healthy Aging Study (EHAS) using the cognitive function instrument (CFI). Three-year average air pollution concentrations for 12 pollutants and 16 nSES characteristics were matched to participants using census tracts. Individual exposure linear regression and LASSO models explore individual exposure effects. Environmental mixture modeling methods including, self-organizing maps (SOM), Bayesian kernel machine regression (BKMR), and quantile-based G-computation explore joint effects, and effect modification between air pollutants and nSES characteristics on cognitive decline.

RESULTS

Participants living in areas with higher air pollution concentrations and lower nSES experienced higher CFI scores (beta: 0.121; 95 % CI: 0.076, 0.167) compared to participants living in areas with low air pollution and high nSES. Additionally, the BKMR model showed a significant overall mixture effect on cognitive decline, suggesting synergy between air pollution and nSES. These joint effects explain protective effects observed in single-pollutant linear regression models, even after adjustment for confounding by nSES (e.g., an IQR increase in CO was associated with a 0.038-point lower (95 % CI: -0.06, -0.01) CFI score).

DISCUSSION

Observed protective effects of single air pollutants on cognitive decline can be explained by joint effects and effect modification of air pollutants and nSES. Researchers must consider nSES as an effect modifier if not a co-exposure to better understand the complex relationships between air pollution and nSES in urban settings.

Biomass fuel use for cooking in Nepalese families and child cognitive abilities, results from a community-based study

BACKGROUND

Biomass fuel use for cooking is widespread in low to middle income countries. Studies on the association between biomass fuel use and cognitive abilities in children are limited.

OBJECTIVE

To examine the association between biomass fuel use for cooking and cognitive abilities in Nepalese children at 4 years of age.

METHODS

In a cohort design we have information on biomass fuel use in the households of 533 children in infancy and cognitive abilities when they were 4 years old from a community-based sample. Cognitive abilities were measured by the Wechsler Preschool and Primary Scale of Intelligence, 4th edition (WPPSI-IV) and the NEPSY-II. We examined the associations between biomass fuel use and scores on the WPPSI-IV Full-Scale IQ (FSIQ) (primary outcome), and WPPSI index and NEPSY-II subtest scores in multiple linear regression models. The associations were also examined in predefined subgroups.

RESULTS

Ninety-nine (18.6%) of the families used biomass fuel for cooking. Children in these families had lower mean FSIQ than children in families with no biomass use (83.3 (95%CI 81.7, 85.0) vs. 85.3 (95%CI 84.5, 86.0)), with a mean difference of -2.2 (95%CI -3.9, -0.5) adjusting for demographics and socio-economic status. The association between biomass fuel use and cognitive abilities was strongest in subgroups of children from households with more than three rooms, with separate kitchen and bedroom, and with higher wealth-score. These interactions were significant for number of rooms in the home (p = 0.04), if the household had separate bedroom and kitchen (p = 0.05), and for the wealth-score (p = 0.03).

CONCLUSION

Biomass fuel use for cooking in Nepalese families was associated with lower overall cognitive abilities at 4 years. Uncertainties include exposure misclassification and unmeasured confounding. The associations between biomass fuel use and neurodevelopment in children needs further investigation with more precise measurements of the exposure.

Exposure to outdoor and indoor air pollution and risk of overweight and obesity across different life periods: A review

Due to the highly evolved industrialization and modernization, air quality has deteriorated in most countries. As reported by the World Health Organization (WHO), air pollution is now considered as one of the major threats to global health and a principal risk factor for noncommunicable diseases. Meanwhile, the increasing worldwide prevalence of overweight and obesity is attracting more public attentions. Recently, accumulating epidemiological studies have provided evidence that overweight and obesity may be partially attributable to environmental exposure to air pollution. This review summarizes the epidemiological evidence for the correlation between exposure to various outdoor and indoor air pollutants (mainly particulate matter (PM), nitrogen oxides (NO_x), ozone (O₃), and polycyclic aromatic hydrocarbons (PAHs)) and overweight and obesity outcomes in recent years. Moreover, it discusses the multiple effects of air pollution during exposure periods throughout life and sex differences in populations. This review also describes the potential mechanism underlying the increased risk of obesity caused by air pollution, including inflammation, oxidative stress, metabolic imbalance, intestinal flora disorders and epigenetic modifications. Finally, this review proposes macro- and micro-measures to prevent the negative effects of air pollution exposure on the obesity prevalence.

The potential involvement of inhaled iron (Fe) in the neurotoxic effects of ultrafine particulate matter air pollution exposure on brain development in mice

BACKGROUND

Air pollution has been associated with neurodevelopmental disorders in epidemiological studies. In our studies in mice, developmental exposures to ambient ultrafine particulate (UFP) matter either postnatally or gestationally results in neurotoxic consequences that include brain metal dyshomeostasis, including significant increases in brain Fe. Since Fe is redox active and neurotoxic to brain in excess, this study examined the extent to which postnatal Fe inhalation exposure, might contribute to the observed neurotoxicity of UFPs. Mice were exposed to 1 µg/m³ Fe oxide nanoparticles alone, or in conjunction with sulfur dioxide (Fe (1 µg/m³) + SO₂ (SO₂ at 1.31 mg/m³, 500 ppb) from postnatal days 4-7 and 10-13 for 4 h/day.

RESULTS

Overarching results included the observations that Fe + SO₂ produced greater neurotoxicity than did Fe alone, that females appeared to show greater vulnerability to these exposures than did males, and that profiles of effects differed by sex. Consistent with metal dyshomeostasis, both Fe only and Fe + SO₂ exposures altered correlations of Fe and of sulfur (S) with other metals in a sex and tissue-specific manner. Specifically, altered metal levels in lung, but particularly in frontal cortex were found, with reductions produced by Fe in females, but increases produced by Fe + SO₂ in males. At PND14, marked changes in brain frontal cortex and striatal neurotransmitter systems were observed, particularly in response to combined Fe + SO2 as compared to Fe only, in glutamatergic and dopaminergic functions that were of opposite directions by sex. Changes in markers of trans-sulfuration in frontal cortex likewise differed in females as compared to males. Residual neurotransmitter changes were limited at PND60. Increases in serum glutathione and Il-1a were female-specific effects of combined Fe + SO2.

CONCLUSIONS

Collectively, these findings suggest a role for the Fe contamination in air pollution in the observed neurotoxicity of ambient UFPs and that such involvement may be different by chemical mixture. Translation of such results to humans requires verification, and, if found, would suggest a need for regulation of Fe in air for public health protection.

Human skin responses to environmental pollutants: A review of current scientific models

Whatever the exposure route, chemical, physical and biological pollutants modify the whole organism response, leading to nerve, cardiac, respiratory, reproductive, and skin system pathologies. Skin acts as a barrier for preventing pollutant modifications. This review aims to present the available scientific models, which help investigate the impact of pollution on the skin. The research question was "Which experimental models illustrate the impact of pollution on the skin in humans?" The review covered a period of 10 years following a PECO statement on in vitro, ex vivo, in vivo and in silico models. Of 582 retrieved articles, 118 articles were eligible. In oral and inhalation routes, dermal exposure had an important impact at both local and systemic levels. Healthy skin models included primary cells, cell lines, co-cultures, reconstructed human epidermis, and skin explants. In silico models estimated skin exposure and permeability. All pollutants affected the skin by altering elasticity, thickness, the structure of epidermal barrier strength, and dermal extracellular integrity. Some specific models concerned wound healing or the skin aging process. Underlying mechanisms were an exacerbated inflammatory skin reaction with the modulation of several cytokines and oxidative stress responses, ending with apoptosis. Pathological skin models revealed the consequences of environmental pollutants on psoriasis, atopic dermatitis, and tumour development. Finally, scientific models were used for evaluating the safety and efficacy of potential skin formulations in preventing the skin aging process or skin irritation after repeated contact. The review gives an overview of scientific skin models used to assess the effects of pollutants. Chemical and physical pollutants were mainly represented while biological contaminants were little studied. In future developments, cell hypoxia and microbiota models may be considered as more representative of clinical situations. Models considering humidity and temperature variations may reflect the impact of these changes.

Microglial Activation and Oxidative Stress in PM2.5-Induced Neurodegenerative Disorders

Fine particulate matter (PM_2.5) pollution remains a prominent environmental problem worldwide, posing great threats to human health. The adverse effects of PM_2.5 on the respiratory and cardiovascular systems have been extensively studied, while its detrimental effects on the central nervous system (CNS), specifically neurodegenerative disorders, are less investigated. Neurodegenerative disorders are characterized by reduced neurogenesis, activated microglia, and neuroinflammation. A variety of studies involving postmortem examinations, epidemiological investigations, animal experiments, and in vitro cell models have shown that PM_2.5 exposure results in neuroinflammation, oxidative stress, mitochondrial dysfunction, neuronal apoptosis, and ultimately neurodegenerative disorders, which are strongly associated with the activation of microglia. Microglia are the major innate immune cells of the brain, surveilling and maintaining the homeostasis of CNS. Upon activation by environmental and endogenous insults, such as PM exposure, microglia can enter an overactivated state that is featured by amoeboid morphology, the over-production of reactive oxygen species, and pro-inflammatory mediators. This review summarizes the evidence of microglial activation and oxidative stress and neurodegenerative disorders following PM_2.5 exposure. Moreover, the possible mechanisms underlying PM_2.5-induced microglial activation and neurodegenerative disorders are discussed. This knowledge provides certain clues for the development of therapies that may slow or halt the progression of neurodegenerative disorders induced by ambient PM.

Hypoxia and Alpha-Synuclein: Inextricable Link Underlying the Pathologic Progression of Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative disease after Alzheimer's disease, with typical motor symptoms as the main clinical manifestations. At present, there are about 10 million patients with PD in the world, and its comorbidities and complications are numerous and incurable. Therefore, it is particularly important to explore the pathogenesis of PD and find possible therapeutic targets. Because the etiology of PD is complex, involving genes, environment, and aging, finding common factors is the key to identifying intervention targets. Hypoxia is ubiquitous in the natural environment and disease states, and it is considered to be closely related to the etiology of PD. Despite research showing that hypoxia increases the expression and aggregation of alpha-synuclein (α-syn), the most important pathogenic protein, there is still a lack of systematic studies on the role of hypoxia in α-syn pathology and PD pathogenesis. Considering that hypoxia is inextricably linked with various causes of PD, hypoxia may be a co-participant in many aspects of the PD pathologic process. In this review, we describe the risk factors for PD, and we discuss the possible role of hypoxia in inducing PD pathology by these risk factors. Furthermore, we attribute the pathological changes caused by PD etiology to oxygen uptake disorder and oxygen utilization disorder, thus emphasizing the possibility of hypoxia as a critical link in initiating or promoting α-syn pathology and PD pathogenesis. Our study provides novel insight for exploring the pathogenesis and therapeutic targets of PD.

Prenatal and early postnatal exposure to ambient particulate matter and early childhood neurodevelopment: A birth cohort study

Adverse impacts of prenatal or postnatal ambient particulate matter exposure have been identified on offspring neurodevelopment. However, it is unclear whether the effect in the two exposure periods is different for early childhood neurodevelopment. This study aimed to evaluate and compare the associations of prenatal and early postnatal exposure to ambient particulate matter with offspring neurodevelopment at 2 years of age and to identify which period was more sensitive to the effects of ambient particulate matter on offspring neurodevelopment. A total of 1331 mother-child pairs from a birth cohort were included in this study from October 2013 to September 2014 in Wuhan, China. The concentrations of ambient daily fine particulate matter (PM_2.5) and particulate matter less than 10 μm in aerodynamic diameter (PM₁₀) at each participant's home address during pregnancy and the first two years after birth were estimated by land-use regression models (LUR). Offspring neurodevelopment was measured by the Chinese revision of Bayley Scale of Infant Development (BSID-CR) for each child at 2 years of age. Mental developmental index (MDI) and psychomotor developmental index (PDI) from the BSID-CR were used as outcome variables. A generalized estimating equation (GEE) model was used to estimate the associations of prenatal and postnatal PM_2.5 and PM₁₀ exposure with offspring neurodevelopment. After adjusting for potential confounders, we found that both prenatal and early postnatal exposure to PM_2.5 and PM₁₀ were associated with decreased offspring MDI and PDI scores. Compared with prenatal exposure, the associations of early postnatal exposure to PM_2.5 and PM₁₀ with offspring MDI and PDI were stronger. This study indicates that exposure to ambient particulate matters, mainly during early postnatal period and to a lesser extent prenatally, is associated with impaired offspring neurodevelopment.

Association of Physical Activity with Incidence of Dementia Is Attenuated by Air Pollution

INTRODUCTION

Physical activity (PA) is recognized as one of the key lifestyle behaviors that reduces risk of developing dementia late in life. However, PA also leads to increased respiration, and in areas with high levels of air pollution, PA may increase exposure to pollutants linked with higher risk of developing dementia. Here, we investigate whether air pollution attenuates the association between PA and dementia risk.

METHODS

This prospective cohort study included 35,562 adults 60 yrs and older from the UK Biobank. Average acceleration magnitude (ACCave) from wrist-worn accelerometers was used to assess PA levels. Air pollution levels (NO, NO2, PM10, PM2.5, PM2.5-10, and PM2.5 absorbance) were estimated with land use regression methods. Incident all-cause dementia was derived from inpatient hospital records and death registry data.

RESULTS

In adjusted models, ACCave was associated with reduced risk of developing dementia (HR = 0.71, 95% confidence interval [CI] = 0.60-0.83), whereas air pollution variables were not associated with dementia risk. There were significant interactions between ACCave and PM2.5 (HRinteraction = 1.33, 95% CI = 1.13-1.57) and PM2.5 absorbance (HRinteraction = 1.24, 95% CI = 1.07-1.45) on incident dementia. At the lowest tertiles of pollution, ACCave was associated with reduced risk of incident dementia (HRPM 2.5 = 0.66, 95% CI = 0.49-0.91; HRPM 2.5 absorbance = 0.60, 95% CI = 0.44-0.81). At the highest tertiles of these pollutants, there was no significant association of ACCave with incident dementia (HRPM 2.5 = 0.88, 95% CI = 0.68-1.14; HRPM 2.5 absorbance = 0.79, 95% CI = 0.60-1.04).

CONCLUSIONS

PA is associated with reduced risk of developing all-cause dementia. However, exposure to even moderate levels of air pollution attenuates the benefits of PA on risk of dementia.

Role of Nrf2 in Parkinson's Disease: Toward New Perspectives

Parkinson's disease (PD) is one of the most common and chronic degenerative diseases in the central nervous system. The main pathology of PD formation is the progressive loss of dopaminergic neurons in substantia nigra and the formation of α-synuclein-rich Lewy bodies. The pathogenesis of PD is not caused by any single independent factor. The diversity of these independent factors of PD, such as iron accumulation, oxidative stress, neuroinflammation, mitochondrial dysfunction, age, environment, and heredity, makes the research progress of PD slow. Nrf2 has been well-known to be closely associated with the pathogenesis of PD and could regulate these induced factors development. Nrf2 activation could protect dopaminergic neurons and slow down the progression of PD. This review summarized the role of Nrf2 pathway on the pathogenesis of PD. Regulation of Nrf2 pathway might be one of the promising strategies to prevent and treat PD.

Ambient Air Pollutants and Incident Microvascular Disease: A Cohort Study

Little is known about the links between long-term exposure to air pollution and risk of incident microvascular disease (retinopathy, peripheral neuropathy, and chronic kidney disease). This study included 396 014 UK residents free of microvascular disease and macrovascular disease at baseline. Annual means of PM2.5, PM2.5-10, PM10, NO2, and NOx were assessed by land use regression models for each participant. A weighted air pollution score was generated from PM10 and NOx. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). During a median follow-up of 11.7 years, 14 327 composite microvascular disease occurred. While none of the air pollutants showed any statistically significant association with the risk of retinopathy, all the air pollutants were linked to the risk of peripheral neuropathy and chronic kidney disease. The adjusted-HRs (95% CIs) for each interquartile range increase in air pollution score were 1.07 (1.05, 1.09), 1.01 (0.94, 1.07), 1.13 (1.08, 1.19), and 1.07 (1.05, 1.10) for overall microvascular disease, retinopathy, peripheral neuropathy, and chronic kidney disease, respectively. In conclusion, long-term exposure to overall air pollution was associated with higher risks of peripheral neuropathy and chronic kidney disease among the general UK population.

Recent Insights into Particulate Matter (PM2.5)-Mediated Toxicity in Humans: An Overview

Several epidemiologic and toxicological studies have commonly viewed ambient fine particulate matter (PM_2.5), defined as particles having an aerodynamic diameter of less than 2.5 µm, as a significant potential danger to human health. PM_2.5 is mostly absorbed through the respiratory system, where it can infiltrate the lung alveoli and reach the bloodstream. In the respiratory system, reactive oxygen or nitrogen species (ROS, RNS) and oxidative stress stimulate the generation of mediators of pulmonary inflammation and begin or promote numerous illnesses. According to the most recent data, fine particulate matter, or PM_2.5, is responsible for nearly 4 million deaths globally from cardiopulmonary illnesses such as heart disease, respiratory infections, chronic lung disease, cancers, preterm births, and other illnesses. There has been increased worry in recent years about the negative impacts of this worldwide danger. The causal associations between PM_2.5 and human health, the toxic effects and potential mechanisms of PM_2.5, and molecular pathways have been described in this review.

Toxicological effects of traffic-related air pollution on the lungs: Evidence, biomarkers and intervention

BACKGROUND

Numerous epidemiological studies have recently observed that exposure to traffic-related air pollution (TRAP) is associated with increased risk of various respiratory diseases. Major gaps in knowledge remain regarding the toxicological effects.

OBJECTIVES

We examined the toxicological effects of the gasoline exhaust particles (GEP), a paradigm of TRAP, in rats, with an objective to provide the evidence, obtain the biomarkers, and suggest effective intervention measure.

METHODS

We measured the airway hyperresponsiveness (AHR), inflammatory cells in the bronchoalveolar lavage (BAL) fluid, histological changes in the lung tissues, and the biomarkers so as to systematically examine the toxicological effects of GEPs at different dose levels (0.5, 2.5, 5 mg/kg BW). The intervention of vitamin E (VE), a natural antioxidant, on the toxicological effects was investigated.

RESULTS

The lung injury caused by GEP exposure was first indicated by the airway hyperresponsiveness (AHR). Compared with the control group, GEP exposure significantly increased the airway resistances and decreased the lung compliance; the higher the dose of GEP, the more serious the lung injury. Lung injury was also revealed by the increase of inflammatory cells, including the lymphocytes and neutrophils, in the BAL fluid. With the increase of GEP dose, histological changes in the lung tissues were further observed: inflammatory cell infiltration increased and alveolar wall thickened. The toxicology of GEP was demonstrated by the increase of the biomarkers of the oxidative stress, the pro-inflammatory cytokines and the apoptosis cytokine. However, administration of VE was found to be effective in restoring airway injury.

CONCLUSION

The toxicological effects of traffic-related air pollution (TRAP) on rat lungs are supported by evidence and biomarkers, and vitamin E intervention is feasible.

In-utero exposure to air pollution and early-life neural development and cognition

Air pollution remains one of the major health threats around the world. Compared to adults, foetuses and infants are more vulnerable to the effects of environmental toxins. Maternal exposure to air pollution causes several adverse birth outcomes and may lead to life-long health consequences. Given that a healthy intrauterine environment is a critical factor for supporting normal foetal brain development, there is a need to understand how prenatal exposure to air pollution affects brain health and results in neurological dysfunction. This review summarised the current knowledge on the adverse effects of prenatal air pollution exposure on early life neurodevelopment and subsequent impairment of cognition and behaviour in childhood, as well as the potential of early-onset neurodegeneration. While inflammation, oxidative stress, and endoplasmic reticulum are closely involved in the physiological response, sex differences also occur. In general, males are more susceptible than females to the adverse effect of in-utero air pollution exposure. Considering the evidence provided in this review and the rising concerns of global air pollution, any efforts to reduce pollutant emission or exposure will be protective for the next generation.

Murine in utero exposure to simulated complex urban air pollution disturbs offspring gut maturation and microbiota during intestinal suckling-to-weaning transition in a sex-dependent manner

Background

Emerging data indicate that prenatal exposure to air pollution may lead to higher susceptibility to several non-communicable diseases. Limited research has been conducted due to difficulties in modelling realistic air pollution exposure. In this study, pregnant mice were exposed from gestational day 10–17 to an atmosphere representative of a 2017 pollution event in Beijing, China. Intestinal homeostasis and microbiota were assessed in both male and female offspring during the suckling-to-weaning transition.

Results

Sex-specific differences were observed in progeny of gestationally-exposed mice. In utero exposed males exhibited decreased villus and crypt length, vacuolation abnormalities, and lower levels of tight junction protein ZO-1 in ileum. They showed an upregulation of absorptive cell markers and a downregulation of neonatal markers in colon. Cecum of in utero exposed male mice also presented a deeply unbalanced inflammatory pattern. By contrast, in utero exposed female mice displayed less severe intestinal alterations, but included dysregulated expression of Lgr5 in colon, Tjp1 in cecum, and Epcam, Car2 and Sis in ileum. Moreover, exposed female mice showed dysbiosis characterized by a decreased weighted UniFrac β-diversity index, a higher abundance of Bacteroidales and Coriobacteriales orders, and a reduced Firmicutes/Bacteroidetes ratio.

Conclusion

Prenatal realistic modelling of an urban air pollution event induced sex-specific precocious alterations of structural and immune intestinal development in mice.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-022-00481-y.

Exposure to traffic-related air pollution and noise during pregnancy and childhood, and functional brain connectivity in preadolescents

BACKGROUND

The amount of people affected by traffic-related air pollution and noise is continuously increasing, but limited research has been conducted on the association between these environmental exposures and functional brain connectivity in children.

OBJECTIVE

This exploratory study aimed to analyze the associations between the exposure to traffic-related air pollution and noise during pregnancy and childhood, and functional brain connectivity amongst a wide-swath of brain areas in preadolescents from 9 to 12 years of age.

METHODS

We used data of 2,197 children from the Generation R Study. Land use regression models were applied to estimate nitrogen oxides and particulate matter levels at participant's homes for several time periods: pregnancy, birth to 3 years, 3 to 6 years, and 6 years of age to the age at magnetic resonance imaging (MRI) assessment. Existing noise maps were used to estimate road traffic noise exposure at participant's homes for the same time periods. Resting-state functional MRI was obtained at 9-12 years of age. Pair-wise correlation coefficients of the blood-oxygen-level-dependent signals between 380 brain areas were calculated. Linear regressions were run and corrected for multiple testing.

RESULTS

Preadolescents exposed to higher levels of NO₂, NO_x, and PM_2.5 absorbance, from birth to 3 years, and from 3 to 6 years of age showed higher correlation coefficients among several brain regions (e.g. from 0.16 to 0.19 higher correlation coefficient related to PM_2.5 absorbance exposure, depending on the brain connection). Overall, most identified associations were between brain regions of the task positive and task negative networks, and were mainly inter-network (20 of 26). Slightly more than half of the connections were intra-hemispheric (14 of 26), predominantly in the right hemisphere. Road traffic noise was not associated with functional brain connectivity.

CONCLUSIONS

This exploratory study found that exposure to traffic-related air pollution during the first years of life was related to higher functional brain connectivity predominantly in brain areas located in the task positive and task negative networks, in preadolescents from 9 to 12 years of age. These results could be an indicator of differential functional connectivity in children exposed to higher levels of air pollution.

Defining the effects of traffic-related air pollution on the human plasma proteome using an aptamer proteomic array: A dose-dependent increase in atherosclerosis-related proteins

BACKGROUND

Traffic-related air pollution (TRAP) is a critical risk factor and major contributor to respiratory and cardiovascular disease (CVD). The effects of TRAP beyond the lungs can be related to changes in circulatory proteins. However, such TRAP-mediated changes have not been defined in an unbiased manner using a controlled human model.

OBJECTIVE

To detail global protein changes (the proteome) in plasma following exposure to inhaled diesel exhaust (DE), a paradigm of TRAP, using controlled human exposures.

METHODS

In one protocol, ex-smokers and never-smokers were exposed to filtered air (FA) and DE (300 μg PM_2.5/m³), on order-randomized days, for 2 h. In a second protocol, independent never-smoking participants were exposed to lower concentrations of DE (20, 50 or 150 μg PM_2.5/m³) and FA, for 4 h, on order-randomized days. Each exposure was separated by 4 weeks of washout. Plasma samples obtained 24 h post-exposure from ex-smokers (n = 6) were first probed using Slow off-rate modified aptamer proteomic array. Plasma from never-smokers (n = 11) was used for independent assessment of proteins selected from the proteomics study by immunoblotting.

RESULTS

Proteomics analyses revealed that DE significantly altered 342 proteins in plasma of ex-smokers (n = 6). The top 20 proteins therein were primarily associated with inflammation and CVD. Plasma from never-smokers (n = 11) was used for independent assessment of 6 proteins, amongst the top 10 proteins increased by DE in the proteomics study, for immunoblotting. The abundance of all six proteins (fractalkine, apolipoproteins (APOB and APOM), IL18R1, MIP-3 and MMP-12) was significantly increased by DE in plasma of these never-smokers. DE-mediated increase was shown to be concentration-dependent for fractalkine, APOB and MMP-12, all biomarkers of atherosclerosis, which correlated with plasma levels of IL-6, a subclinical marker of CVD, in independent participants.

CONCLUSION

This investigation details changes in the human plasma proteome due to TRAP. We identify specific atherosclerosis-related proteins that increase concentration-dependently across a range of TRAP levels applicable worldwide.

Ambient air pollution exposure and increasing depressive symptoms in older women: The mediating role of the prefrontal cortex and insula

Exposures to fine particulate matter (PM_2.5) and nitrogen dioxide (NO₂) have been associated with the emergence of depressive symptoms in older adulthood, although most studies used cross-sectional outcome measures. Elucidating the brain structures mediating the adverse effects can strengthen the causal role between air pollution and increasing depressive symptoms. We evaluated whether smaller volumes of brain structures implicated in late-life depression mediate associations between ambient air pollution exposure and changes in depressive symptoms. This prospective study included 764 community-dwelling older women (aged 81.6 ± 3.6 in 2008-2010) from the Women's Health Initiative Memory Study (WHIMS) Magnetic Resonance Imaging study (WHIMS-MRI; 2005-06) and WHIMS-Epidemiology of Cognitive Health Outcomes (WHIMS-ECHO; 2008-16). Three-year average annual mean concentrations (scaled by interquartile range [IQR]) of ambient PM_2.5 (in μg/m³; IQR = 3.14 μg/m³) and NO₂ (in ppb; IQR = 7.80 ppb) before WHIMS-MRI were estimated at participants' addresses via spatiotemporal models. Mediators included structural brain MRI-derived grey matter volumes of the prefrontal cortex and structures of the limbic-cortical-striatal-pallidal-thalamic circuit. Depressive symptoms were assessed annually by the 15-item Geriatric Depression Scale. Structural equation models were constructed to estimate associations between exposure, structural brain volumes, and depressive symptoms. Increased exposures (by each IQR) were associated with greater annual increases in depressive symptoms (β_PM2.5 = 0.022; 95% Confidence Interval (CI) = 0.003, 0.042; β_NO2 = 0.019; 95% CI = 0.001, 0.037). The smaller volume of prefrontal cortex associated with exposures partially mediated the associations of increased depressive symptoms with NO₂ (8%) and PM_2.5 (13%), and smaller insula volume associated with NO₂ contributed modestly (13%) to the subsequent increase in depressive symptoms. We demonstrate the first evidence that the smaller volumes of the prefrontal cortex and insula may mediate the subsequent increases in depressive symptoms associated with late-life exposures to NO₂ and PM_2.5.

Environmentally Persistent Free Radical Promotes Lung Cancer Progression by Regulating the Expression Profile of miRNAs

Background: Environmentally persistent free radicals (EPFRs) are generated in the combustion processes of solid waste and can cause adverse influences on human health, especially lung diseases. Lung cancer is one of the most serious malignancies in recent years, which the global deaths rate is about 1.6 million every year. Methods and Results: In this study, we verified that ZnO/MCB EPFRs promote cell proliferation and migration, impedes cell apoptosis in lung cancer. Furthermore, we found that ZnO/MCB could influence the expression of miRNAs (miR-18a and miR-34a). In vivo, ZnO/MCB and ZnO EPFRs can reduce the weight and survival rate of BALB/c male mice more than that of BALB/c female mice. In the ZnO/MCB exposed group, male mice lung became even smaller, while the female mice the lung increased significantly. Taken together, our results provide evidence for assessing the potential health risks of persistent free radicals on fine particles. Conclusions: This study linked toxicity of EPFRs with miRNAs revealed the potential health hazard to human lung cancer.

Possible association between PM2.5 and neurodegenerative diseases: A systematic review

Air pollution is one of the most serious environmental problems that afflict our planet and one of the greatest risk factors for human health. In particular, PM_2.5 is able to cross the blood-alveolar and blood-brain barriers, thus increasing the onset of respiratory, cardiovascular and neurodegenerative diseases. Neurodegenerative disease is a progressive neuronal dysfunction that leads to neuronal lesions in both structure and function, and includes several diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), vascular dementia (VaD), multiple sclerosis (MS), and others. We carried out a systematic review using PRISMA approach to investigate on the possible association between exposure to PM_2.5 and neurodegenerative diseases. The international databases (PubMed, Science Direct, Web of Sciences) were used to find published studies on the topic. The search period was between January 2011 and June 2021. About 2000 full research articles were selected, and finally, we included 20 full-research articles. Selected studies have highlighted how PM_2.5 exposure can be associated with the onset of neurodegenerative diseases (AD, PD, MS, VaD). This association depends not only on age, PM_2.5 levels and exposure time, but also on exposure to other air pollutants, proximity to areas with high vehicular traffic, and the presence of comorbidities. Exposure to PM_2.5 promotes neuroinflammation processes, because through breathing the particles can reach the nasal epithelial mucosa and transferred to the brain through the olfactory bulb. Furthermore, exposure to PM_2.5 has been associated with an increased expression of markers of neurodegenerative diseases (e.g. alpha-synuclein or beta-amyloid), which can contribute to the etiopathogenesis of neurodegenerative diseases. Although many studies have revealed the pathological relationship between PM_2.5 exposure and cognitive impairment, the potential cellular and molecular mechanisms of PM_2.5 leading to neurodegenerative disease remain not entirely clear, and then, further studies need to be carried out on the topic.

Assessing the association between air pollution and child development in São Paulo, Brazil

Background

Outdoor air pollution is increasingly recognised as a key threat to population health globally, with particularly high risks for urban residents. In this study, we assessed the association between residential nitrogen dioxide (NO₂) exposure and children’s cognitive and behavioural development using data from São Paulo Brazil, one of the largest urban agglomerations in the world.

Methods

We used data from the São Paulo Western Region Birth Cohort, a longitudinal cohort study aiming to examine determinants as well as long-term implications of early childhood development. Cross-sectional data from the 72-month follow-up was analysed. Data on NO₂ concentration in the study area was collected at 80 locations in 2019, and land use regression modelling was used to estimate annual NO₂ concentration at children’s homes. Associations between predicted NO₂ exposure and children’s cognitive development as well as children’s behavioural problems were estimated using linear regression models adjusted for an extensive set of confounders. All results were expressed per 10 μg/m³ increase in NO2.

Results

1143 children were included in the analysis. We found no association between NO₂ and children’s cognitive development (beta -0.05, 95% CI [-0.20; 0.10]) or behavioural problems (beta 0.02, 95% CI [-0.80; 0.12]).

Conclusion

No association between child cognition or child behaviour and NO₂ was found in this cross-sectional analysis. Further research will be necessary to understand the extent to which these null results reflect a true absence of association or other statistical, biological or adaptive factors not addressed in this paper.

Role of Environmental Toxicants on Neurodegenerative Disorders

Neurodegeneration leads to the loss of structural and functioning components of neurons over time. Various studies have related neurodegeneration to a number of degenerative disorders. Neurological repercussions of neurodegeneration can have severe impacts on the physical and mental health of patients. In the recent past, various neurodegenerative ailments such as Alzheimer’s and Parkinson’s illnesses have received global consideration owing to their global occurrence. Environmental attributes have been regarded as the main contributors to neural dysfunction-related disorders. The majority of neurological diseases are mainly related to prenatal and postnatal exposure to industrially produced environmental toxins. Some neurotoxic metals, like lead (Pb), aluminium (Al), Mercury (Hg), manganese (Mn), cadmium (Cd), and arsenic (As), and also pesticides and metal-based nanoparticles, have been implicated in Parkinson’s and Alzheimer’s disease. The contaminants are known for their ability to produce senile or amyloid plaques and neurofibrillary tangles (NFTs), which are the key features of these neurological dysfunctions. Besides, solvent exposure is also a significant contributor to neurological diseases. This study recapitulates the role of environmental neurotoxins on neurodegeneration with special emphasis on major neurodegenerative disorders such as Alzheimer’s and Parkinson’s disease.

Differential effects of Urban Particulate Matter on BV2 microglial-like and C17.2 neural stem/precursor cells

Air pollution affects the majority of the world's population and has been linked to over 7 million premature deaths per year. Exposure to particulate matter (PM) contained within air pollution is associated with cardiovascular, respiratory and neurological ill health. There is increasing evidence that exposure to air pollution in utero and in early childhood is associated with altered brain development. However, the underlying mechanisms for impaired brain development are not clear. While oxidative stress and neuroinflammation are documented consequences of PM exposure, cell-specific mechanisms that may be triggered in response to air pollution exposure are less well defined. Here we assess the effect of urban (U)PM exposure on two different cell types, microglial-like BV2 cells and neural stem / precursor-like C17.2 cells. We found that, contrary to expectations, immature C17.2 cells were more resistant to PM-mediated oxidative stress and cell death than BV2 cells. PM exposure resulted in decreased mitochondrial health and increased mitochondrial ROS in BV2 cells which could be prevented by mitoTEMPO antioxidant treatment. Our data suggest that not only is mitochondrial dysfunction a key trigger in PM-mediated cytotoxicity, but that such deleterious effects may also depend on cell type and maturity.

Air pollution and neurodevelopmental skills in preschool- and school-aged children: A systematic review

Early life exposure to air pollution has been associated with neurodevelopmental disorders. Emerging evidence are highlighting a possible impact of air pollution on typically developing children. Thirty papers were included in this review to systematically evaluate the association between air pollutants exposure in prenatal and/or postnatal periods and specific neurodevelopmental skills (i.e. intellective functioning, memory and learning, attention and executive functions, verbal language, numeric ability and motor and/or sensorimotor functions) in preschool- and school-age children. Detrimental effects of air pollutants on children's neurodevelopmental skills were observed, although they do not show clinically relevant performance deficits. The most affected domains were global intellective functioning and attention/executive functions. The pollutants that seem to represent the greatest risk are PM2.5, NO₂ and PAHs. Prenatal exposure is primarily associated with child neurodevelopment at pre-school and school ages. Early exposure to air pollutants is related to adverse neurodevelopmental outcomes in the general population of children. Further research is needed to support stronger conclusions.

Association of both prenatal and early childhood multiple metals exposure with neurodevelopment in infant: A prospective cohort study

BACKGROUND

Impaired neurodevelopment of children has become a growing public concern; however, the associations between metals exposure and neurocognitive function have remained largely unknown.

OBJECTIVES

We systematically evaluated the associations of multiple metals exposure during pregnancy and childhood on the neurodevelopment of children aged 2-3 years.

METHODS

We measured 22 metals in the serum and urine among703 mother-child pairs from the Guangxi Birth Cohort Study. The neurocognitive development of children was assessed by the Gesell Development Diagnosis Scale (GDDS; Chinese version). Multiple linear regression models were used to evaluate the relationship between the metals (selected by elastic net regression) and the outcomes. The Bayesian kernel machine regression (BKMR) was used to evaluate the possible joint effect between the multiple metal mixture and the outcomes.

RESULTS

Prenatal aluminum (Al) exposure was negatively associated with the fine motor developmental quotient (DQ) (β = -1.545, 95%CI: 2.231, -0.859), adaption DQ (β = -1.182, 95%CI: 1.632, -0.732), language DQ (β = -1.284, 95% CI: 1.758, -0.809), and social DQ (β = -1.729, 95% CI: 2.406, -1.052) in the multi-metal model. Prenatal cadmium (Cd) exposure was negatively associated with gross motor DQ (β = -2.524, 95% CI: 4.060, -0.988), while postpartum Cd exposure was negatively associated with language DQ (β = -1.678, 95% CI: 3.227, -0.129). In stratified analyses, infants of different sexes had different sensitivities to metal exposure, and neurobehavioral development was more significantly affected by metal exposure in the first and second trimester. BKMR analysis revealed a negative joint effect of the Al, Cd, and selenium (Se) on the language DQ score; postpartum Cd exposure played a major role in this relationship.

CONCLUSION

Prenatal exposure to Al, Ba, Cd, molybdenum (Mo), lead (Pb), antimony (Sb), and strontium (Sr), and postpartum exposure to cobalt (Co), Cd, stannum (Sn), iron (Fe), nickel (Ni), and Se are associated with neurological development of infants. The first and second trimester might be the most sensitive period when metal exposure affects neurodevelopment.

Neurotoxicity induced by toluene: In silico and in vivo evidences of mitochondrial dysfunction and dopaminergic neurodegeneration

Toluene is an air pollutant widely used as an organic solvent in industrial production and emitted by fossil fuel combustion, in addition to being used as a drug of abuse. Its toxic effects in the central nervous system have not been well established, and how and which neurons are affected remains unknown. Hence, this study aimed to fill this gap by investigating three central questions: 1) How does toluene induce neurotoxicity? 2) Which neurons are affected? And 3) What are the long-term effects induced by airborne exposure to toluene? To this end, a Caenorhabditis elegans model was employed, in which worms at the fourth larval stage were exposed to toluene in the air for 24 h in a vapor chamber to simulate four exposure scenarios. After the concentration-response curve analysis, we chose scenarios 3 (E3: 792 ppm) and 4 (E4: 1094 ppm) for the following experiments. The assays were performed 1, 48, or 96 h after removal from the exposure environments, and an irreversible reduction in neuron fluorescence and morphologic alterations were observed in different neurons of exposed worms, particularly in the dopaminergic neurons. Moreover, a significant impairment in a dopaminergic-dependent behavior was also associated with negative effects in healthspan endpoints, and we also noted that mitochondria may be involved in toluene-induced neurotoxicity since lower adenosine 5'-triphosphate (ATP) levels and mitochondrial viability were observed. In addition, a reduction of electron transport chain activity was evidenced using ex vivo protocols, which were reinforced by in silico and in vitro analysis, demonstrating toluene action in the mitochondrial complexes. Based on these findings model, it is plausible that toluene neurotoxicity can be initiated by complex I inhibition, triggering a mitochondrial dysfunction that may lead to irreversible dopaminergic neuronal death, thus impairing neurobehavioral signaling.

Emulating Near-Roadway Exposure to Traffic-Related Air Pollution via Real-Time Emissions from a Major Freeway Tunnel System

Epidemiological and toxicological studies continue to demonstrate correlative and causal relationships between exposure to traffic-related air pollution and various metrics of adverse pulmonary, cardiovascular, and neurological health effects. The key challenge for in vivo studies is replicating real-world, near-roadway exposure dynamics in laboratory animal models that mimic true human exposures. The advantage of animal models is the accelerated time scales to show statistically significant physiological and/or behavioral response. This work describes a novel exposure facility adjacent to a major freeway tunnel system that provides a platform for real-time chronic exposure studies. The primary conclusion is that particulate matter (PM) concentrations at this facility are routinely well below the National Ambient Air Quality Standards (NAAQS), but studies completed to date still demonstrate significant neurological and cardiovascular effects. Internal combustion engines produce large numbers of ultrafine particles that contribute negligible mass to the atmosphere relative to NAAQS regulated PM2.5 but have high surface area and mobility in the body. It is posited here that current federal and state air quality standards are thus insufficient to fully protect human health, most notably the developing and aging brain, due to regulatory gaps for ultrafine particles.

A New Method for the Assessment of the Oxidative Potential of Both Water-Soluble and Insoluble PM

Water-soluble and insoluble fractions of airborne particulate matter (PM) exhibit different toxicological potentials and peculiar mechanisms of action in biological systems. However, most of the research on the oxidative potential (OP) of PM is focused exclusively on its water-soluble fraction, since experimental criticisms were encountered for detaching the whole PM (soluble and insoluble species) from field filters. However, to estimate the actual potential effects of PM on human health, it is essential to assess the OP of both its water-soluble and insoluble fractions. In this study, to estimate the total OP (TOP), an efficient method for the detachment of intact PM10 from field filters by using an electrical toothbrush was applied to 20 PM10 filters in order to obtain PM10 water suspensions to be used for the DCFH, AA and DTT oxidative potential assays (OPDCFH, OPAA and OPDTT). The contribution of the insoluble PM10 to the TOP was evaluated by comparing the TOP values to those obtained by applying the three OP assays to the water-soluble fraction of 20 equivalent PM10 filters. The OP of the insoluble fraction (IOP) was calculated as the difference between the TOP and the WSOP. Moreover, each PM10 sample was analyzed for the water-soluble and insoluble fractions of 10 elements (Al, Cr, Cs, Cu, Fe, Li, Ni, Rb, Sb, Sn) identified as primary elemental tracers of the main emission sources in the study area. A principal component analysis (PCA) was performed on the data obtained to identify the predominant sources for the determination of TOP, WSOP, and IOP. Results showed that water-soluble PM10 released by traffic, steel plant, and biomass burning is mainly responsible for the generation of the TOP as well as of the WSOP. This evidence gave strength to the reliability of the results from OP assays performed only on the water-soluble fraction of PM. Lastly, the IOPDCFH and IOPDTT were found to be principally determined by insoluble PM10 from mineral dust.

Association of improved air quality with lower dementia risk in older women

Late-life ambient air pollution is a risk factor for brain aging, but it remains unknown if improved air quality (AQ) lowers dementia risk. We studied a geographically diverse cohort of older women dementia free at baseline in 2008 to 2012 (n = 2,239, aged 74 to 92). Incident dementia was centrally adjudicated annually. Yearly mean concentrations of fine particulate matter (PM2.5) and nitrogen dioxide (NO2) were estimated using regionalized national universal kriging models and averaged over the 3-y period before baseline (recent exposure) and 10 y earlier (remote exposure). Reduction from remote to recent exposures was used as the indicator of improved AQ. Cox proportional hazard ratios (HRs) for dementia risk associated with AQ measures were estimated, adjusting for sociodemographic, lifestyle, and clinical characteristics. We identified 398 dementia cases during follow up (median = 6.1 y). PM2.5 and NO2 reduced significantly over the 10 y before baseline. Larger AQ improvement was associated with reduced dementia risks (HRPM2.5 0.80 per 1.78 μg/m3, 95% CI 0.71-0.91; HRNO2 0.80 per 3.91 parts per billion, 95% CI 0.71-0.90), equivalent to the lower risk observed in women 2.4 y younger at baseline. Higher PM2.5 at baseline was associated with higher dementia risk (HRPM2.5 1.16 per 2.90 μg/m3, 95% CI 0.98-1.38), but the lower dementia risk associated with improved AQ remained after further adjusting for recent exposure. The observed associations did not substantially differ by age, education, geographic region, Apolipoprotein E e4 genotypes, or cardiovascular risk factors. Long-term AQ improvement in late life was associated with lower dementia risk in older women.