Exposure to elemental composition of outdoor PM2.5 at birth and cognitive and psychomotor function in childhood in four European birth cohorts

Associations between Fine Particulate Matter Components, Their Sources, and Cognitive Outcomes in Children Ages 9-10 Years Old from the United States

BACKGROUND

Emerging literature suggests that fine particulate matter [with aerodynamic diameter ≤ 2.5 μ m (PM 2.5 )] air pollution and its components are linked to various neurodevelopmental outcomes. However, few studies have evaluated how PM 2.5 component mixtures from distinct sources relate to cognitive outcomes in children.

OBJECTIVES

This cross-sectional study investigated how ambient concentrations of PM 2.5 component mixtures relate to neurocognitive performance in 9- to 10-year-old children, as well as explored potential source-specific effects of these associations, across the US.

METHODS

Using spatiotemporal hybrid models, annual concentrations of 15 chemical components of PM 2.5 were estimated based on the residential address of child participants from the Adolescent Brain Cognitive Development (ABCD) Study. General cognitive ability, executive function, and learning/memory scores were derived from the NIH Toolbox. We applied positive matrix factorization to identify six major PM 2.5 sources based on the 15 components, which included crustal, ammonium sulfate, biomass burning, traffic, ammonium nitrate, and industrial/residual fuel burning. We then utilized weighted quantile sum (WQS) and linear regression models to investigate associations between PM 2.5 components' mixture, their potential sources, and children's cognitive scores.

RESULTS

Mixture modeling revealed associations between cumulative exposure and worse cognitive performance across all three outcome domains, including shared overlap in detrimental effects driven by ammonium nitrates, silicon, and calcium. Using the identified six sources of exposure, source-specific negative associations were identified between ammonium nitrates and learning & memory, traffic and executive function, and crustal and industrial mixtures and general cognitive ability. Unexpected positive associations were also seen between traffic and general ability as well as biomass burning and executive function.

DISCUSSION

This work suggests nuanced associations between outdoor PM 2.5 exposure and childhood cognitive performance, including important differences in cognition related both to individual chemicals as well as to specific sources of these exposures. https://doi.org/10.1289/EHP14418.

Can the aerosol pollution extreme events be revealed by global reanalysis products?

Extreme aerosol pollution poses significant risks to the climate, environment, and human health. To investigate the formation and impacts of aerosol pollution extreme events (APEE), the reanalysis product presents meticulous spatiotemporal information on the three-dimensional distribution of aerosols. However, there is a lack of comprehensive evaluation and information regarding the data quality of reanalysis products employed in APEE research, as well as limited understanding of their spatial and temporal distribution, variation, and long-term trends. To address this scientific gap, we conducted a global study for distribution and variation patterns of APEE using two widely-used reanalysis products, MERRA-2 (Modern-Era Retrospective Analysis for Research-2) and CAMS (Copernicus Atmospheric Monitoring Service). The APEE was defined here as a day when the daily aerosol optical depth (AOD) exceeding its 90th percentile for a given station and month. Eleven distinct land regions worldwide were selected for evaluation by comparing both reanalysis products with MODIS satellite products and ground-based observations in terms of frequency, intensity, and temporal trends of APEE. The analysis indicates that MERRA-2 and CAMS exhibit high matching rates (70 % and 80 %, respectively) in terms of occurrence timeline for APEE at monthly and seasonal scales, while also exhibiting strong monthly correlation coefficients (>0.65) with ground-based observations over selected regions. The total AOD (-0.002 ∼ -0.123 decade-1), APEE AOD (-0.004 ∼ -0.293 decade-1), and APEE frequency (-0.264 ∼ -1.769 day month-1 decade-1) of both observations and reanalysis products in most regions showed a decreasing trend with various magnitude, except for some regions such as South Asia where the trend is increasing. Based on the aforementioned evaluation, it is evident that reanalysis products are effective and useful in identifying the temporal trends associated with APEE.

Childhood exposure to outdoor air pollution in different microenvironments and cognitive and fine motor function in children from six European cohorts

BACKGROUND

Exposure to air pollution during childhood has been linked with adverse effects on cognitive development and motor function. However, limited research has been done on the associations of air pollution exposure in different microenvironments such as home, school, or while commuting with these outcomes.

OBJECTIVE

To analyze the association between childhood air pollution exposure in different microenvironments and cognitive and fine motor function from six European birth cohorts.

METHODS

We included 1301 children from six European birth cohorts aged 6-11 years from the HELIX project. Average outdoor air pollutants concentrations (NO2, PM2.5) were estimated using land use regression models for different microenvironments (home, school, and commute), for 1-year before the outcome assessment. Attentional function, cognitive flexibility, non-verbal intelligence, and fine motor function were assessed using the Attention Network Test, Trail Making Test A and B, Raven Colored Progressive Matrices test, and the Finger Tapping test, respectively. Adjusted linear regressions models were run to determine the association between each air pollutant from each microenvironment on each outcome.

RESULTS

In pooled analysis we observed high correlation (rs = 0.9) between air pollution exposures levels at home and school. However, the cohort-by-cohort analysis revealed correlations ranging from low to moderate. Air pollution exposure levels while commuting were higher than at home or school. Exposure to air pollution in the different microenvironments was not associated with working memory, attentional function, non-verbal intelligence, and fine motor function. Results remained consistently null in random-effects meta-analysis.

CONCLUSIONS

No association was observed between outdoor air pollution exposure in different microenvironments (home, school, commute) and cognitive and fine motor function in children from six European birth cohorts. Future research should include a more detailed exposure assessment, considering personal measurements and time spent in different microenvironments.

Prenatal ambient air pollutant mixture exposure and neurodevelopment in urban children in the Northeastern United States

BACKGROUND

Studies of prenatal air pollution (AP) exposure on child neurodevelopment have mostly focused on a single pollutant. We leveraged daily exposure data and implemented novel data-driven statistical approaches to assess effects of prenatal exposure to a mixture of seven air pollutants on cognitive functioning in school-age children from an urban pregnancy cohort.

METHODS

Analyses included 236 children born at ≥37 weeks gestation. Maternal prenatal daily exposure levels for nitrogen dioxide (NO2), ozone (O3), and constituents of fine particles [elemental carbon (EC), organic carbon (OC), nitrate (NO3-), sulfate (SO42-), ammonium (NH4+)] were estimated based on residential addresses using validated satellite-based hybrid models or global 3-D chemical-transport models. Children completed Wide Range Assessment of Memory and Learning (WRAML-2) and Conners' Continuous Performance Test (CPT-II) at 6.5 ± 0.9 years of age. Time-weighted levels for mixture pollutants were estimated using Bayesian Kernel Machine Regression Distributed Lag Models (BKMR-DLMs), with which we also explored the interactions in the exposure-response functions among pollutants. Resulting time-weighted exposure levels were used in Weighted Quantile Sum (WQS) regressions to examine AP mixture effects on outcomes, adjusted for maternal age, education, child sex, and prenatal temperature.

RESULTS

Mothers were primarily ethnic minorities (81% Hispanic and/or black) reporting ≤12 years of education (68%). Prenatal AP mixture (per unit increase in WQS estimated AP index) was associated with decreased WRAML-2 general memory (GM; β = -0.64, 95%CI = -1.40, 0.00) and memory-related attention/concentration (AC; β = -1.03, 95%CI = -1.78, -0.27) indices, indicating poorer memory functioning, as well as increased CPT-II omission errors (OE; β = 1.55, 95%CI = 0.34, 2.77), indicating increased attention problems. When stratified by sex, association with AC index was significant among girls, while association with OE was significant among boys. Traffic-related pollutants (NO2, OC, EC) and SO42- were major contributors to these associations. There was no significant evidence of interactions among mixture components.

CONCLUSIONS

Prenatal exposure to an AP mixture was associated with child neurocognitive outcomes in a sex- and domain-specific manner.

Neurotoxicity of the air-borne particles: From molecular events to human diseases

Exposure to PM_2.5 is associated with an increased incidence of CNS diseases in humans, as confirmed by numerous epidemiological studies. Animal models have demonstrated that PM_2.5 exposure can damage brain tissue, neurodevelopmental issues and neurodegenerative diseases. Both animal and human cell models have identified oxidative stress and inflammation as the primary toxic effects of PM_2.5 exposure. However, understanding how PM_2.5 modulates neurotoxicity has proven challenging due to its complex and variable composition. This review aims to summarize the detrimental effects of inhaled PM_2.5 on the CNS and the limited understanding of its underlying mechanism. It also highlights new frontiers in addressing these issues, such as modern laboratory and computational techniques and chemical reductionism tactics. By utilizing these approaches, we aim to fully elucidate the mechanism of PM_2.5-induced neurotoxicity, treat associated diseases, and ultimately eliminate pollution.

Air pollution during the perinatal period and neurodevelopment in children: A national population study in Taiwan

AIM

To evaluate the association between ambient particulate matter no larger than 2.5 μm in diameter (PM2.5 ) during the prenatal and postnatal periods and infant neurodevelopmental parameters.

METHOD

We conducted a population-based birth cohort study using the Taiwan Birth Cohort Study. Participants were assessed for developmental conditions through home interviews at 6 months and 18 months of age. Exposure to PM2.5 of mothers and infants during perinatal periods was estimated using hybrid kriging/land-use regression. The exposure was linked to each participant by home address. Logistic regression was then conducted to determine the risk of neurodevelopmental delay in relation to PM2.5 .

RESULTS

A total of 17 683 term singletons without congenital malformations were included in the final analysis. PM2.5 during the second trimester was associated with increased risks of delays in gross motor neurodevelopmental milestones (adjusted odds ratio [aOR] 1.09 per 10 μg/m3 increase in exposure to PM2.5 ). Delayed fine motor development was also found to be related to exposure to PM2.5 in the second and third trimesters (aOR 1.06), as was personal-social skill (aOR 1.11 for the second trimester and 1.06 for the third). These neurodevelopmental parameters were unrelated to postnatal PM2.5 exposure.

INTERPRETATION

Exposure to ambient PM2.5 during pregnancy was significantly related to delay in gross motor, fine motor, and personal-social development in this population-based study.

WHAT THIS PAPER ADDS

Prenatal exposure to higher PM2.5 was associated with increased risk of delayed early neurodevelopment. The critical period for delayed gross motor development was the second trimester. The critical period for fine motor and personal-social development was the second and third trimesters.

Air pollution and human cognition: A systematic review and meta-analysis

BACKGROUND

This systematic review summarises and evaluates the literature investigating associations between exposure to air pollution and general population cognition, which has important implications for health, social and economic inequalities, and human productivity.

METHODS

The engines MEDLINE, Embase Classic+Embase, APA PsycInfo, and SCOPUS were searched up to May 2022. Our inclusion criteria focus on the following pollutants: particulate matter, NOx, and ozone. The cognitive abilities of interest are: general/global cognition, executive function, attention, working memory, learning, memory, intelligence and IQ, reasoning, reaction times, and processing speed. The collective evidence was assessed using the NTP-OHAT framework and random-effects meta-analyses.

RESULTS

Eighty-six studies were identified, the results of which were generally supportive of associations between exposures and worsened cognition, but the literature was varied and sometimes contradictory. There was moderate certainty support for detrimental associations between PM_2.5 and general cognition in adults 40+, and PM_2.5, NOx, and PM₁₀ and executive function (especially working memory) in children. There was moderate certainty evidence against associations between ozone and general cognition in adults age 40+, and NOx and reasoning/IQ in children. Some associations were also supported by meta-analysis (N = 14 studies, all in adults aged 40+). A 1 μg/m³ increase in NO₂ was associated with reduced performance on general cognitive batteries (β = -0.02, p < 0.05) as was a 1 μg/m³ increase in PM_2.5 exposure (β = -0.02, p < 0.05). A 1μgm³ increase in PM_2.5 was significantly associated with lower verbal fluency by -0.05 words (p = 0.01) and a decrease in executive function task performance of -0.02 points (p < 0.001).

DISCUSSION

Evidence was found in support of some exposure-outcome associations, however more good quality research is required, particularly with older teenagers and young adults (14-40 years), using multi-exposure modelling, incorporating mechanistic investigation, and in South America, Africa, South Asia and Australasia.

Associations of Autism Spectrum Disorder with PM2.5 Components: A Comparative Study Using Two Different Exposure Models

This retrospective cohort study examined associations of autism spectrum disorder (ASD) with prenatal exposure to major fine particulate matter (PM2.5) components estimated using two independent exposure models. The cohort included 318 750 mother-child pairs with singleton deliveries in Kaiser Permanente Southern California hospitals from 2001 to 2014 and followed until age five. ASD cases during follow-up (N = 4559) were identified by ICD codes. Prenatal exposures to PM2.5, elemental (EC) and black carbon (BC), organic matter (OM), nitrate (NO3-), and sulfate (SO42-) were constructed using (i) a source-oriented chemical transport model and (ii) a hybrid model. Exposures were assigned to each maternal address during the entire pregnancy, first, second, and third trimester. In single-pollutant models, ASD was associated with pregnancy-average PM2.5, EC/BC, OM, and SO42- exposures from both exposure models, after adjustment for covariates. The direction of effect estimates was consistent for EC/BC and OM and least consistent for NO3-. EC/BC, OM, and SO42- were generally robust to adjustment for other components and for PM2.5. EC/BC and OM effect estimates were generally larger and more consistent in the first and second trimester and SO42- in the third trimester. Future PM2.5 composition health effect studies might consider using multiple exposure models and a weight of evidence approach when interpreting effect estimates.

Prenatal exposure to tailpipe and non-tailpipe tracers of particulate matter pollution and autism spectrum disorders

BACKGROUND

Traffic-related air pollution exposure is associated with increased risk of autism spectrum disorder (ASD). It is unknown whether carbonaceous material from vehicular tailpipe emissions or redox-active non-tailpipe metals, eg. from tire and brake wear, are responsible. We assessed ASD associations with fine particulate matter (PM_2.5) tracers of tailpipe (elemental carbon [EC] and organic carbon [OC]) and non-tailpipe (copper [Cu]; iron [Fe] and manganese [Mn]) sources during pregnancy in a large cohort.

METHODS

This retrospective cohort study included 318,750 children born in Kaiser Permanente Southern California (KPSC) hospitals during 2001-2014, followed until age 5. ASD cases were identified by ICD codes. Monthly estimates of PM_2.5 and PM_2.5 constituents EC, OC, Cu, Fe, and Mn with 4 km spatial resolution were obtained from a source-oriented chemical transport model. These exposures and NO₂ were assigned to each maternal address during pregnancy, and associations with ASD were assessed using Cox regression models adjusted for covariates. PM constituent effect estimates were adjusted for PM_2.5 and NO₂ to assess independent effects. To distinguish ASD risk associated with non-tailpipe from tailpipe sources, the associations with Cu, Fe, and Mn were adjusted for EC and OC, and vice versa.

RESULTS

There were 4559 children diagnosed with ASD. In single-pollutant models, increased ASD risk was associated with gestational exposures to tracers of both tailpipe and non-tailpipe emissions. The ASD hazard ratios (HRs) per inter-quartile increment of exposure) for EC, OC, Cu, Fe, and Mn were 1.11 (95% CI: 1.06-1.16), 1.09 (95% CI: 1.04-1.15), 1.09 (95% CI: 1.04-1.13), 1.14 (95% CI: 1.09-1.20), and 1.17 (95% CI: 1.12-1.22), respectively. Estimated effects of Cu, Fe, and Mn (reflecting non-tailpipe sources) were largely unchanged in two-pollutant models adjusting for PM_2.5, NO₂, EC or OC. In contrast, ASD associations with EC and OC were markedly attenuated by adjustment for non-tailpipe sources.

CONCLUSION

Results suggest that non-tailpipe emissions may contribute to ASD. Implications are that reducing tailpipe emissions, especially from vehicles with internal combustion engines, may not eliminate ASD associations with traffic-related air pollution.

Neonatal exposure to ultrafine iron but not combined iron and sulfur aerosols recapitulates air pollution-induced impulsivity in mice

Air pollution (AP) is becoming recognized as a major threat to neurological health across the lifespan with increased risk of both neurodevelopmental and neurodegenerative disorders. AP is a complex mixture of gases and particulate matter, with adsorbed contaminants including metals and trace elements, which may differentially contribute to its neurodevelopmental impacts. Iron (Fe) is one of the most abundant metals found in AP, and Fe concentrations may drive some behavioral deficits observed in children. Furthermore, brains of neonate mice exposed to concentrated ambient ultrafine particulate matter (UFP) show significant brain accumulation of Fe and sulfur (S) supporting the hypothesis that AP exposure may lead to brain metal dyshomeostasis. The current study determined the extent to which behavioral effects of UFP, namely memory deficits and impulsive-like behavior, could be recapitulated with exposure to Fe aerosols with or without concomitant SO2. Male and female neonate mice were either exposed to filtered air or spark discharge-generated ultrafine Fe particles with or without SO2 gas (n = 12/exposure/sex). Inhalation exposures occurred from postnatal day (PND) 4-7 and 10-13 for 4 hr/day, mirroring our previous UFP exposures. Mice were aged to adulthood prior to behavioral testing. While Fe or Fe + SO2 exposure did not affect gross locomotor behavior, Fe + SO2-exposed females displayed consistent thigmotaxis during locomotor testing. Neither exposure affected novel object memory. Fe or Fe + SO2 exposure produced differential outcomes on a fixed-interval reinforcement schedule with males showing higher (Fe-only) or lower (Fe + SO2) response rates and postreinforcement pauses (PRP) and females showing higher (Fe-only) PRP. Lastly, Fe-exposed, but not Fe + SO2-exposed, males showed increased impulsive-like behavior in tasks requiring response inhibition with no such effects in female mice. These findings suggest that: 1) exposure to realistic concentrations of Fe aerosols can recapitulate behavioral effects of UFP exposure, 2) the presence of SO2 can modulate behavioral effects of Fe inhalation, and 3) brain metal dyshomeostasis may be an important factor in AP neurotoxicity.

Effects of prenatal exposure to PM2.5 and its composition on cognitive and motor functions in children at 12 months of age: The Shanghai Birth Cohort Study

BACKGROUND

Prenatal fine particulate matter (PM_2.5) exposure has been linked to infant cognitive and motor functions, but the effects of PM_2.5 chemical composition remain unclear.

OBJECTIVES

We aimed to explore the associations of prenatal PM_2.5 and its composition exposure with infant cognitive and motor functions.

METHODS

We studied 2,435 mother-infant pairs in the Shanghai Birth Cohort Study. PM_2.5 and its seven compositions [primary particles (black carbon, mineral dust and sea salts) and secondary particles (NH₄⁺, NO₃^-, SO₄^2- and organic matter)] during thethreetrimesters ofpregnancy were retrieved from the V4.CH.03 product developed by using a combined geoscience-statistical method. At the 12-month-old follow-up, infant cognitive and motor functions in five domains were assessed using the Ages and Stages Questionnaire (ASQ). We used multivariable linear regressions to estimate the effects of PM_2.5 and its composition on the ASQ scores, for all infants and stratifying by sex and breastfeeding duration.

RESULTS

PM_2.5 exposure was negatively associated with gross motor, problem-solving and personal-social scores for all infants. PM_2.5 compositions were inversely associated with ASQ scores in all five domains, and the effects of different compositions varied across domains. Specifically, all compositions except organic matter were correlated with lower problem-solving scores [e.g., ( [Formula: see text]  =  - 10.79, 95 % CI: -17.40, -4.18) ∼ ( [Formula: see text]  =  - 4.68, 95 % CI: -7.84, -1.53); for each 10 μg/m³ increase in PM_2.5 compositions during the third trimester]. Primary and some secondary particles (organic matter, NO₃^-) were related to lower gross motor scores. Secondary particles were also inversely associated with communication (organic matter and NO₃^-), fine motor (NH₄⁺, NO₃^-, SO₄^2-) and personal-social (NH₄⁺) scores. Additionally, boys and infants breastfed for < 6 months appeared to be more susceptible.

CONCLUSIONS

We found negative associations of PM_2.5 and its compositions with infant cognitive and motor functions over a range of domains, especially the problem-solving domain.

Exposure to fine particulate matter constituents and cognitive function performance, potential mediation by sleep quality: A multicenter study among Chinese adults aged 40-89 years

Although exposure to fine particulate matter (PM_2.5) has been associated with cognitive decline, little is known about which PM_2.5 constituents are more harmful. Recent study on the association between PM_2.5 and sleep quality prompted us to propose that sleep quality may mediate the adverse effects of PM_2.5 components on cognitive decline. Understanding the association between PM_2.5 constituents and cognitive function, as well as the mediating role of sleep quality provides a future intervention target for improving cognitive function. Using data involving 1834 participants from a multicenter cross-sectional study in nine cities of the Beijing-Tianjin-Hebei (BTH) region in China, we undertook multivariable linear regression analyses to quantify the association of annual moving-average PM_2.5 and its chemical constituents with cognitive function and to assess the modifying role of exposure characteristic in this association. Besides, we examined the extent to which this association of PM_2.5 constituents with cognitive function was mediated via sleep quality by a mediation analysis. We observed significantly negative associations between an increase of one interquartile range increase in PM_2.5 [-0.876 (95 % CI: -1.205, -0.548)], organic carbon [-0.481 (95 % CI: -0.744, -0.219)], potassium [-0.344 (95 % CI: -0.530, -0.157)], iron [-0.468 (95 % CI: -0.646, -0.291)], and ammonium ion [-0.125 (95 % CI: -0.197, -0.052)] and cognitive decline. However, we didn't find any individual components more harmful than PM_2.5. Poor sleep quality partially mediated the estimated associations, which were explained ranging from 2.28 % to 11.99 %. Stratification analyses showed that people living in areas with lower greenspace were more susceptible to specific PM_2.5 components. Our study suggests that the adverse effect of suffering from PM_2.5 components is more pronounced among individuals with poor sleep quality, amplifying environmental inequalities in health. Besides reducing environmental pollution, improving sleep quality may be another measure worth considering to improve cognition if our research is confirmed in the future.

Innovative experimental approach for spatial mapping of source-specific risk contributions of potentially toxic trace elements in PM10

Exposure to potentially toxic trace elements (PTTEs) in inhalable particulate matter (PM₁₀) is associated with an increased risk of developing cardiorespiratory diseases. Therefore, in multi-source polluted urban contexts, a spatially-resolved evaluation of health risks associated with exposure to PTTEs in PM is essential to identify critical risk areas. In this study, a very-low volume device for high spatial resolution sampling and analysis of PM₁₀ was employed in Terni (Central Italy) in a wide and dense network (23 sampling sites, about 1 km between each other) during a 15-month monitoring campaign. The soluble and insoluble fraction of 33 elements in PM₁₀ was analysed through a chemical fractionation procedure that increased the selectivity of the elements as source tracers. Total carcinogenic risk (CR) and non-carcinogenic risk (NCR) for adults and children due to concentrations of PTTEs in PM₁₀ were calculated and quantitative source-specific risk apportionment was carried out by applying Positive Matrix Factorization (PMF) to the spatially-resolved concentrations of the chemically fractionated elements. PMF analysis identified 5 factors: steel plant, biomass burning, brake dust, soil dust and road dust. Steel plant showed the greatest risk contribution. Total CR and NCR, and source-specific risk contributions at the 23 sites were interpolated using the ordinary kriging (OK) method and mapped to geo-reference the health risks of the identified sources in the whole study area. This also allowed risk estimation in areas not directly measured and the assessment of the risk contribution of individual sources at each point of the study area. This innovative experimental approach is an effective tool to localize the health risks of spatially disaggregated sources of PTTEs and it may allow for better planning of control strategies and mitigation measures to reduce airborne pollutant concentrations in urban settings polluted by multiple sources.

Prenatal exposure to air pollution is associated with altered brain structure, function, and metabolism in childhood

BACKGROUND

Prenatal exposure to air pollution disrupts cognitive, emotional, and behavioral development. The brain disturbances associated with prenatal air pollution are largely unknown.

METHODS

In this prospective cohort study, we estimated prenatal exposures to fine particulate matter (PM_2.5 ) and polycyclic aromatic hydrocarbons (PAH), and then assessed their associations with measures of brain anatomy, tissue microstructure, neurometabolites, and blood flow in 332 youth, 6-14 years old. We then assessed how those brain disturbances were associated with measures of intelligence, ADHD and anxiety symptoms, and socialization.

RESULTS

Both exposures were associated with thinning of dorsal parietal cortices and thickening of postero-inferior and mesial wall cortices. They were associated with smaller white matter volumes, reduced organization in white matter of the internal capsule and frontal lobe, higher metabolite concentrations in frontal cortex, reduced cortical blood flow, and greater microstructural organization in subcortical gray matter nuclei. Associations were stronger for PM_2.5 in boys and PAH in girls. Youth with low exposure accounted for most significant associations of ADHD, anxiety, socialization, and intelligence measures with cortical thickness and white matter volumes, whereas it appears that high exposures generally disrupted these neurotypical brain-behavior associations, likely because strong exposure-related effects increased the variances of these brain measures.

CONCLUSIONS

The commonality of effects across exposures suggests PM_2.5 and PAH disrupt brain development through one or more common molecular pathways, such as inflammation or oxidative stress. Progressively higher exposures were associated with greater disruptions in local volumes, tissue organization, metabolite concentrations, and blood flow throughout cortical and subcortical brain regions and the white matter pathways interconnecting them. Together these affected regions comprise cortico-striato-thalamo-cortical circuits, which support the regulation of thought, emotion, and behavior.

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.

Health Outcomes in Children Associated with Prenatal and Early-Life Exposures to Air Pollution: A Narrative Review

(1) Background: The developmental origins of health and disease (DOHaD) hypothesis links adverse fetal exposures with developmental mal-adaptations and morbidity later in life. Short- and long-term exposures to air pollutants are known contributors to health outcomes; however, the potential for developmental health effects of air pollution exposures during gestation or early-childhood have yet to be reviewed and synthesized from a DOHaD lens. The objective of this study is to summarize the literature on cardiovascular and metabolic, respiratory, allergic, and neuropsychological health outcomes, from prenatal development through early childhood, associated with early-life exposures to outdoor air pollutants, including traffic-related and wildfire-generated air pollutants. (2) Methods: We conducted a search using PubMed and the references of articles previously known to the authors. We selected papers that investigated health outcomes during fetal or childhood development in association with early-life ambient or source-specific air pollution exposure. (3) Results: The current literature reports that prenatal and early-childhood exposures to ambient and traffic-related air pollutants are associated with a range of adverse outcomes in early life, including cardiovascular and metabolic, respiratory and allergic, and neurodevelopmental outcomes. Very few studies have investigated associations between wildfire-related air pollution exposure and health outcomes during prenatal, postnatal, or childhood development. (4) Conclusion: Evidence from January 2000 to January 2022 supports a role for prenatal and early-childhood air pollution exposures adversely affecting health outcomes during development. Future studies are needed to identify both detrimental air pollutants from the exposure mixture and critical exposure time periods, investigate emerging exposure sources such as wildfire, and develop feasible interventional tools.

A three-dimensional LUR framework for PM2.5 exposure assessment based on mobile unmanned aerial vehicle monitoring

Land use regression (LUR) models have been widely used in epidemiological studies and risk assessments related to air pollution. Although efforts have been made to improve the performance of LUR models so that they capture the spatial heterogeneity of fine particulate matter (PM_2.5) in high-density cities, few studies have revealed the vertical differences in PM_2.5 exposure. This study proposes a three-dimensional LUR (3-D LUR) assessment framework for PM_2.5 exposure that combines a high-resolution LUR model with a vertical PM_2.5 variation model to investigate the results of horizontal and vertical mobile PM_2.5 monitoring campaigns. High-resolution LUR models that were developed independently for daytime and nighttime were found to explain 51% and 60% of the PM_2.5 variation, respectively. Vertical measurements of PM_2.5 from three regions were first parameterized to produce a coefficient of variation for the concentration (CVC) to define the rate at which PM_2.5 changes at a certain height relative to the ground. The vertical variation model for PM_2.5 was developed based on a spline smoothing function in a generalized additive model (GAM) framework with an adjusted R² of 0.91 and explained 92.8% of the variance. PM_2.5 exposure levels for the population in the study area were estimated based on both the LUR models and the 3-D LUR framework. The 3-D LUR framework was found to improve the accuracy of exposure estimation in the vertical direction by avoiding exposure estimation errors of up to 5%. Although the 3-D LUR-based assessment did not indicate significant variation in estimates of premature mortality that could be attributed to PM_2.5, exposure to this pollutant was found to differ in the vertical direction. The 3-D LUR framework has the potential to provide accurate exposure estimates for use in future epidemiological studies and health risk assessments.

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.

Long-term exposure to ambient air pollution and incidence of depression: A population-based cohort study in China

BACKGROUND

Long-term exposure to ambient air pollution was linked to depression incidence, although the results were limited and inconsistent.

OBJECTIVES

To investigate the effects of long-term air pollution exposure on depression risk prospectively in China.

METHODS

The present study used data from Yinzhou Cohort on adults without depression at baseline, and followed up until April 2020. Two-year moving average concentrations of particulate matter with a diameter ≤ 2.5 μm (PM_2.5), ≤10 μm (PM₁₀) and nitrogen dioxide (NO₂) were measured using land-use regression (LUR) models for each participant. Depression cases were ascertained using the Health Information System (HIS) of the local health administration by linking the unique identifiers. We conducted Cox regression models with time-varying exposures to estimate the hazard ratios (HRs) and 95% confidence intervals (95% CIs) of depression with each pollutant, after adjusting for a sequence of individual covariates as demographic characteristics, lifestyles, and comorbidity. Besides, physical activity, baseline potential depressive symptoms, cancer status, COVID-19 pandemic, different outcome definitions and air pollution exposure windows were considered in sensitivity analyses.

RESULTS

Among the 30,712 adults with a mean age of 62.22 ± 11.25, 1024 incident depression cases were identified over totaling 98,619 person-years of observation. Interquartile range increments of the air pollutants were associated with increased risks of depression, and the corresponding HRs were 1.59 (95%CI: 1.46, 1.72) for PM_2.5, 1.49 (95%CI: 1.35, 1.64) for PM₁₀ and 1.58 (95%CI: 1.42, 1.77) for NO₂. Subgroup analyses suggested that participants without taking any protective measures towards air pollution were more susceptible. The results remained robust in all sensitivity analyses.

CONCLUSIONS

Long-term exposure to ambient air pollution was identified as a risk factor for depression onset. Strategies to reduce air pollution are necessary to decrease the disease burden of depression.

Urban environment and cognitive and motor function in children from four European birth cohorts

BACKGROUND

The urban environment may influence neurodevelopment from conception onwards, but there is no evaluation of the impact of multiple groups of exposures simultaneously. We investigated the association between early-life urban environment and cognitive and motor function in children.

METHODS

We used data from 5403 mother-child pairs from four population-based birth-cohorts (UK, France, Spain, and Greece). We estimated thirteen urban home exposures during pregnancy and childhood, including: built environment, natural spaces, and air pollution. Verbal, non-verbal, gross motor, and fine motor functions were assessed using validated tests at five years old. We ran adjusted multi-exposure models using the Deletion-Substitution-Addition algorithm.

RESULTS

Higher greenness exposure within 300 m during pregnancy was associated with higher verbal abilities (1.5 points (95% confidence interval 0.4, 2.7) per 0.20 unit increase in greenness). Higher connectivity density within 100 m and land use diversity during pregnancy were related to lower verbal abilities. Childhood exposure to PM2.5 mediated 74% of the association between greenness during childhood and verbal abilities. Higher exposure to PM2.5 during pregnancy was related to lower fine motor function (-1.2 points (-2.1, -0.4) per 3.2 μg/m3 increase in PM2.5). No associations were found with non-verbal abilities and gross motor function.

DISCUSSION

This study suggests that built environment, greenness, and air pollution may impact child cognitive and motor function at five years old. This study adds evidence that well-designed urban planning may benefit children's cognitive and motor development.

Mapping Total Exceedance PM2.5 Exposure Risk by Coupling Social Media Data and Population Modeling Data

The PM2.5 exposure risk assessment is the foundation to reduce its adverse effects. Population survey-related data have been deficient in high spatiotemporal detailed descriptions. Social media data can quantify the PM2.5 exposure risk at high spatiotemporal resolutions. However, due to the no-sample characteristics of social media data, PM2.5 exposure risk for older adults is absent. We proposed combining social media data and population survey-derived data to map the total PM2.5 exposure risk. Hourly exceedance PM2.5 exposure risk indicators based on population modeling (HEPEpmd) and social media data (HEPEsm) were developed. Daily accumulative HEPEsm and HEPEpsd ranged from 0 to 0.009 and 0 to 0.026, respectively. Three peaks of HEPEsm and HEPEpsd were observed at 13:00, 18:00, and 22:00. The peak value of HEPEsm increased with time, which exhibited a reverse trend to HEPEpsd. The spatial center of HEPEsm moved from the northwest of the study area to the center. The spatial center of HEPEpsd moved from the northwest of the study area to the southwest of the study area. The expansion area of HEPEsm was nearly 1.5 times larger than that of HEPEpsd. The expansion areas of HEPEpsd aggregated in the old downtown, in which the contribution of HEPEpsd was greater than 90%. Thus, this study introduced various source data to build an easier and reliable method to map total exceedance PM2.5 exposure risk. Consequently, exposure risk results provided foundations to develop PM2.5 pollution mitigation strategies as well as scientific supports for sustainability and eco-health achievement.

Contribution of Aerosol Sources to Health Impacts

Atmospheric aerosol is one of the major leading environmental risk factors for human health worldwide, potentially causing several million premature deaths per year [...]

Oxidative Potential of Atmospheric Aerosols

Atmospheric particulate matter (PM) is one of the leading health risks worldwide [...]

The Relationship Between Air Pollution and Cognitive Functions in Children and Adolescents: A Systematic Review

Air pollution has a negative impact on one's health and on the central nervous system. We decided to assess studies that evaluated the relationship between air pollution and cognitive functions in children and adolescents by reviewing studies that had been published between January 2009 and May 2019. We searched three major databases for original works (26 studies) and for studies using brain imaging methods based on MRI (six studies). Adverse effects of air pollutants on selected cognitive or psychomotor functions were found in all of the studies. Exposure to nitrogen dioxide, for example, was linked to impaired working memory, general cognitive functions, and psychomotor functions; particulate matter 2.5 was linked to difficulties in working memory, short-term memory, attention, processing speed, and fine motor function; black carbon was linked to poor verbal intelligence, nonverbal intelligence, and working memory; airborne copper was linked to impaired attentiveness and fine motor skills; isophorone was linked to lower mathematical skills; and polycyclic aromatic hydrocarbons in fetal life were linked to lower intelligence scores. The studies using MRI showed that high concentrations of air pollutants were linked to changes in the brain's white matter or lower functional integration and segregation in children's brain networks. In view of the global increase in air pollution, there is a need for further research to elucidate the relationship between air pollution and cognitive and motor development in children. According to some studies, neuroinflammation, the e4 allele of the apolipoprotein E gene, and gutathione-S-transferase gene polymorphism processes may play a role.

Spatial mapping and size distribution of oxidative potential of particulate matter released by spatially disaggregated sources

The ability of particulate matter (PM) to induce oxidative stress is frequently estimated by acellular oxidative potential (OP) assays, such as ascorbic acid (AA) and 1,4-dithiothreitol (DTT), used as proxy of reactive oxygen species (ROS) generation in biological systems, and particle-bound ROS measurement, such as 2',7'-dichlorodihydrofluorescein (DCFH) assay. In this study, we evaluated the spatial and size distribution of OP results obtained by three OP assays (OP^AA, OP^DCFH and OP^DTT), to qualitative identify the relative relevance of single source contributions in building up OP values and to map the PM potential to induce oxidative stress in living organisms. To this aim, AA, DCFH and DTT assays were applied to size-segregated PM samples, collected by low-pressure cascade impactors, and to PM₁₀ samples collected at 23 different sampling sites (about 1 km between each other) in Terni, an urban and industrial hot-spot of Central Italy, by using recently developed high spatial resolution samplers of PM, which worked in parallel during three monitoring periods (February, April and December 2017). The sampling sites were chosen for representing the main spatially disaggregated sources of PM (vehicular traffic, rail network, domestic heating, power plant for waste treatment, steel plant) present in the study area. The obtained results clearly showed a very different sensitivity of the three assays toward each local PM source. OP^AA was particularly sensitive toward coarse particles released from the railway, OP^DCFH was sensible to fine particles released from the steel plant and domestic biomass heating, and OP^DTT was quite selectively sensitive toward the fine fraction of PM released by industrial and biomass burning sources.

Air Pollution-Related Brain Metal Dyshomeostasis as a Potential Risk Factor for Neurodevelopmental Disorders and Neurodegenerative Diseases

Increasing evidence links air pollution (AP) exposure to effects on the central nervous system structure and function. Particulate matter AP, especially the ultrafine (nanoparticle) components, can carry numerous metal and trace element contaminants that can reach the brain in utero and after birth. Excess brain exposure to either essential or non-essential elements can result in brain dyshomeostasis, which has been implicated in both neurodevelopmental disorders (NDDs; autism spectrum disorder, schizophrenia, and attention deficit hyperactivity disorder) and neurodegenerative diseases (NDGDs; Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, and amyotrophic lateral sclerosis). This review summarizes the current understanding of the extent to which the inhalational or intranasal instillation of metals reproduces in vivo the shared features of NDDs and NDGDs, including enlarged lateral ventricles, alterations in myelination, glutamatergic dysfunction, neuronal cell death, inflammation, microglial activation, oxidative stress, mitochondrial dysfunction, altered social behaviors, cognitive dysfunction, and impulsivity. Although evidence is limited to date, neuronal cell death, oxidative stress, and mitochondrial dysfunction are reproduced by numerous metals. Understanding the specific contribution of metals/trace elements to this neurotoxicity can guide the development of more realistic animal exposure models of human AP exposure and consequently lead to a more meaningful approach to mechanistic studies, potential intervention strategies, and regulatory requirements.

Prenatal PM2.5 exposure and behavioral development in children from Mexico City

BACKGROUND

Childhood exposure to air pollution has been linked with maladaptive cognitive development; however, less is known about the association between prenatal fine particulate matter (PM_2.5) exposure and childhood behavior.

OBJECTIVES

Our aim was to assess the association between prenatal PM_2.5 exposure and behavioral development in 4-6 year old children residing in Mexico City.

METHODS

We used data from 539 mother-child pairs enrolled in a prospective birth cohort in Mexico City. We estimated daily PM_2.5 exposure using a 1 km² satellite-based exposure model and averaged over each trimester of pregnancy. We assessed childhood behavior at 4-6 years of age using the parent-completed Behavioral Assessment Scale for Children (BASC-2) composite scores and subscales. We used linear regression models to estimate change in BASC-2 T-scores with trimester specific 5-μg/m³ increases in PM_2.5. All models were mutually adjusted for PM_2.5 exposures during the other trimesters, maternal factors including age, education, socioeconomic status, depression, and IQ, child's age at study visit, and season. We additionally assessed sex-specific effects by including an interaction term between PM_2.5 and sex.

RESULTS

Higher first trimester PM_2.5 exposure was associated with reduced Adaptive Skills scores (β: -1.45, 95% CI: -2.60, -0.30). Lower scores on the Adaptive Skills composite score and subscales indicate poorer functioning. For PM_2.5 exposure during the first trimester, decrements were consistent across adaptive subscale scores including Adaptability (β: -1.51, 95% CI: -2.72, -0.30), Social Skills (β: -1.63, 95% CI: -2.90, -0.36), and Functional Communication (β: -1.21, 95% CI: -2.21, -0.21). The association between 1^st trimester PM_2.5 and depression was stronger in males than females (β for males: 1.52, 95% CI: -0.41, 3.45; β for females: -0.13, 95% CI: -1.99, 1.72; p-int: 0.07).

CONCLUSIONS

Exposure to PM_2.5 during early pregnancy may be associated with impaired behavioral development in children, particularly for measures of adaptive skills. These results suggest that air pollution impacts behavioral domains as well as cognition, and that the timing of exposure may be critical.

Particulate Matter 2.5 Induced Developmental Cardiotoxicity in Chicken Embryo and Hatchling

Particulate matter poses health risk to developing organisms. To investigate particulate matters with a diameter smaller than 2.5 um (PM2.5)-induced developmental cardiotoxicity, fertile chicken eggs were exposed to PM2.5 via air cell injection at doses of 0.05, 0.2, 0.5, 2, and 5 mg/egg kg. Morphological changes in the embryonic day four (ED4) and hatchling hearts were assessed with histological techniques. Heart rates of hatchling chickens were measured with electrocardiography. The protein expression levels of nuclear factor kappa-light-chain-enhancer of activated B cells p65 (NF-kb p65), inducible nitric oxide synthase (iNOS), and matrix metallopeptidase 9 (MMP9) were assessed with immunohistochemistry or western blotting in hatchling hearts. PM2.5 exposure elevated areas of heart in ED4 embryo, increased heart rate, and thickened right ventricular wall thickness in hatchling chickens. Immunohistochemistry revealed enhanced NF-kb p65 expression in hatchling hearts. Western blotting results indicated that both iNOS and MMP9 expression were enhanced by lower doses of PM2.5 exposure (0.2 and 0.5 mg/kg) but not 2 mg/kg. In summary, developmental exposure to PM2.5 induced developmental cardiotoxicity in chicken embryo and hatchling chickens, which is associated with NF-kb p65, iNOS, and MMP9.

Recent advances in understanding the mechanisms of PM2.5-mediated neurodegenerative diseases

PM_2.5 particles are widely believed to be associated with respiratory and cardiovascular diseases. However, recent studies have reported that PM_2.5 may be associated with neurodegenerative diseases. The exact mechanism by which PM_2.5 mediates neurotoxicity and cognitive dysfunction is still unclear. In the current work, we collected evidence supporting the association between PM_2.5 exposure and development of neurodegenerative disorders. Evidence from epidemiological investigations, animal experiments, and ex vivo cell experiments showed that PM_2.5 exposure may lead to neuroinflammation, oxidative stress, mitochondrial dysfunction, neuronal apoptosis, synaptic damage and ultimately neurodegenerative diseases.

Exposure to household air pollution during first 3 years of life and IQ level among 6-8-year-old children in India - A cross-sectional study

Many illnesses have been attributed to the exposure of solid biomass smoke but the effect on intelligence has largely been unexplored. The study aims to examine the effect of exposure to solid biomass smoke during the first 3 years of life on intelligence among 6-8-year-old children. Children aged 6-8 years were enrolled from a primary school and their houses were visited to collect data on socio-economic status and household exposure assessment. Households using LPG as cooking fuel were considered as the unexposed group. All the children were tested for their Intelligence Quotient (IQ) using Malin's Intelligence Scale for Indian Children (MISIC). The mean IQ was calculated as the average of Verbal and Performance score. Potential confounders were adjusted using multivariate general linear model. About 45% of children had average or above-average IQ while the rest had below-average IQ. The mean scores for the arithmetic component of IQ were found to be significantly lower among solid biomass fuel users as compared to LPG users after adjusting for confounders. The mean IQ of LPG users were 5.58 points higher (95% CI: 0.46-10.1) for the arithmetic component as compared to solid biomass users. Children living in the houses using solid biomass fuel for cooking have lower IQ as compared to the children living in the houses using LPG for cooking for arithmetic component even after adjusting for potential confounders.

Hazardous air pollutants are associated with worse performance in reading, math, and science among US primary schoolchildren

Emerging evidence demonstrates that chronic exposure to air pollution may negatively impact children's cognitive processing and memory. Little is currently known about how air pollution impacts individual children's academic performance through time. Academic performance is practically important, given its linkage to children's future life course trajectories. Individual-level, longitudinal data from 16,000 US primary school students are combined with a tract-level hazardous air pollutant (HAP) measure to assess how kindergarten exposures are associated with competencies in reading, math and science through third grade. We employed linear mixed models with repeated measures within children (e.g., five math tests across four years), clustering within census tracts, and random effects specified at the child- and census tract-levels. Controlling for a comprehensive list of time variant and time invariant covariates, we found statistically significant associations between higher levels of HAPs and lower reading (b = -0.02; p < 0.05), math (b = -0.02; p < 0.001), and science (b = -0.05; p < 0.001) scores. These negative effects of pollution on academic competency in the early primary school years add to the weight of evidence that air pollution harms children's academic potential.

Burden of typical diseases attributed to the sources of PM2.5-bound toxic metals in Beijing: An integrated approach to source apportionment and QALYs

PM_2.5-bound toxic metals (TMs) are derived from various sources, and they can cause many adverse health effects on the human body. To effectively reduce the disease burden of TMs by controlling the relative sources, an integrated approach of quality-adjusted life years (QALYs) and source-apportionment (positive matrix factorization, PMF) was proposed and applied to some typical diseases induced by TMs in 2017 in Beijing. The estimation included two parts; first, the number of potentially affected people was calculated based on the source mass contribution from PMF and the inhalation unit risk of TMs; second, the QALYs lost per affected person was calculated based on the disease duration, expected years of life lost (EYLL) and quality of life (QoL) for both affected people and the general population. The results showed that QALYs lost per person for renal cancer (17.3 QALYs), pneumonia (14.4 QALYs), lung cancer (14.2 QALYs), skin cancer (12.7 QALYs) and diabetes mellitus (12.6 QALYs) were higher than those for other diseases. Combined with PMF, the source contributions to the overall burden of typical diseases from the TMs followed the order of coal combustion (50.2%) > vehicle emissions (24.4%) > fuel oil combustion (11.4%) > Cr-related industry (10.9%) > resuspended dust (3.0%). The rank was further compared with that assessed for noncancer and cancer risks, and we verified the reasonability of the QALYs method. For seasonal contributions to coal combustion, winter and spring had the highest contributions, which coincided with the fact that coal was the main fuel for heating in Beijing. The QALYs lost attributed to TMs for coal combustion decreased by 49.1% from 2016 to 2017, which may indicate an effective policy associated with coal control. Overall, the integrated approach was successfully employed for estimating the disease burden induced by TMs from each source and was an effective solution to identify the control rank of sources for TM reduction.

Prenatal and postnatal exposure to air pollution and emotional and aggressive symptoms in children from 8 European birth cohorts

BACKGROUND

The association between air pollution exposure and emotional and behavioural problems in children is unclear. We aimed to assess prenatal and postnatal exposure to several air pollutants and child's depressive and anxiety symptoms, and aggressive symptoms in children of 7-11 years.

METHODS

We analysed data of 13182 children from 8 European population-based birth cohorts. Concentrations of nitrogen dioxide (NO₂), nitrogen oxides (NO_x), particulate matter (PM) with diameters of ≤10 μm (PM₁₀), ≤ 2.5 μm (PM_2.5), and between 10 and 2.5 μm (PM_coarse), the absorbance of PM_2.5 filters (PM_2.5abs), and polycyclic aromatic hydrocarbons (PAHs) were estimated at residential addresses of each participant. Depressive and anxiety symptoms and aggressive symptoms were assessed at 7-11 years of age using parent reported tests. Children were classified in borderline/clinical range or clinical range using validated cut offs. Region specific models were adjusted for various socio-economic and lifestyle characteristics and then combined using random effect meta-analysis. Multiple imputation and inverse probability weighting methods were applied to correct for potential attrition bias.

RESULTS

A total of 1896 (14.4%) children were classified as having depressive and anxiety symptoms in the borderline/clinical range, and 1778 (13.4%) as having aggressive symptoms in the borderline/clinical range. Overall, 1108 (8.4%) and 870 (6.6%) children were classified as having depressive and anxiety symptoms, and aggressive symptoms in the clinical range, respectively. Prenatal exposure to air pollution was not associated with depressive and anxiety symptoms in the borderline/clinical range (e.g. OR 1.02 [95%CI 0.95 to 1.10] per 10 μg/m³ higher NO₂) nor with aggressive symptoms in the borderline/clinical range (e.g. OR 1.04 [95%CI 0.96 to 1.12] per 10 μg/m³ higher NO₂). Similar results were observed for the symptoms in the clinical range, and for postnatal exposures to air pollution.

CONCLUSIONS

Overall, our results suggest that prenatal and postnatal exposure to air pollution is not associated with depressive and anxiety symptoms or aggressive symptoms in children of 7 to 11 years old.

Myo-inositol mediates the effects of traffic-related air pollution on generalized anxiety symptoms at age 12 years

BACKGROUND

Exposure to traffic-related air pollution (TRAP) has been linked to childhood anxiety symptoms. Neuroimaging in patients with anxiety disorders indicate altered neurochemistry.

OBJECTIVES

Evaluate the impact of TRAP on brain metabolism and its relation to childhood anxiety symptoms in the Cincinnati Childhood Allergy and Air Pollution Study (CCAAPS).

METHODS

Adolescents (n = 145) underwent magnetic resonance spectroscopy. Brain metabolites, including myo-inositol, N-acetylaspartate, creatine, choline, glutamate, glutamate plus glutamine, and glutathione were measured in the anterior cingulate cortex. Anxiety symptoms were assessed using the Spence Children's Anxiety Scale. TRAP exposure in early-life, averaged over childhood, and during the 12 months prior to imaging was estimated using a validated land use regression model. Associations between TRAP exposure, brain metabolism, and anxiety symptoms were estimated using linear regression and a bootstrapping approach for testing mediation by brain metabolite levels.

RESULTS

Recent exposure to high levels of TRAP was associated with significant increases in myo-inositol (β = 0.26; 95%CI 0.01, 0.51) compared to low TRAP exposure. Recent elevated TRAP exposure (β = 4.71; 95% CI 0.95, 8.45) and increased myo-inositol levels (β = 2.98; 95% CI 0.43, 5.52) were also significantly associated with increased generalized anxiety symptoms with 12% of the total effect between TRAP and generalized anxiety symptoms being mediated by myo-inositol levels.

CONCLUSIONS

This is the first study of children to utilize neuroimaging to link TRAP exposure, metabolite dysregulation in the brain, and generalized anxiety symptoms among otherwise healthy children. TRAP may elicit atypical excitatory neurotransmission and glial inflammatory responses leading to increased metabolite levels and subsequent anxiety symptoms.

Air Pollution Exposure During Fetal Life, Brain Morphology, and Cognitive Function in School-Age Children

BACKGROUND

Air pollution exposure during fetal life has been related to impaired child neurodevelopment, but it is unclear if brain structural alterations underlie this association. The authors assessed whether air pollution exposure during fetal life alters brain morphology and whether these alterations mediate the association between air pollution exposure during fetal life and cognitive function in school-age children.

METHODS

We used data from a population-based birth cohort set up in Rotterdam, The Netherlands (2002-2006). Residential levels of air pollution during the entire fetal period were calculated using land-use regression models. Structural neuroimaging and cognitive function were performed at 6 to 10 years of age (n = 783). Models were adjusted for several socioeconomic and lifestyle characteristics.

RESULTS

Mean fine particle levels were 20.2 μg/m³ (range, 16.8-28.1 μg/m³). Children exposed to higher particulate matter levels during fetal life had thinner cortex in several brain regions of both hemispheres (e.g., cerebral cortex of the precuneus region in the right hemisphere was 0.045 mm thinner (95% confidence interval, 0.028-0.062) for each 5-μg/m³ increase in fine particles). The reduced cerebral cortex in precuneus and rostral middle frontal regions partially mediated the association between exposure to fine particles and impaired inhibitory control. Air pollution exposure was not associated with global brain volumes.

CONCLUSIONS

Exposure to fine particles during fetal life was related to child brain structural alterations of the cerebral cortex, and these alterations partially mediated the association between exposure to fine particles during fetal life and impaired child inhibitory control. Such cognitive impairment at early ages could have significant long-term consequences.