The association between particulate matter 2.5 exposure and children with autism spectrum disorder

Connecting the dots: environmental pollution and Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a complex neurodevelopmental condition characterized by challenges in social communication and repetitive behavior. While the exact etiology of ASD remains elusive, researchers have increasingly turned their attention to the role of environmental factors in its development. Among these factors, environmental pollution has emerged as a potential contributor to the rising prevalence of ASD cases worldwide. This review delves into the growing body of scientific evidence suggesting a significant association between environmental pollution and the risk of ASD. It explores the environmental pollution that have been implicated, including air pollution, water contaminants, heavy metals, pesticides, and endocrine-disrupting chemicals. The detrimental impact of these pollutants on the developing brain, particularly during critical periods of gestation and early childhood has been discussed. This will provide insights into the possible mechanisms by which the various pollutants may influence the neurodevelopmental pathways underlying ASD. Additionally, the potential interplay between genetic susceptibility and environmental exposure is explored to better understand the multifactorial nature of ASD causation. Considering the alarming increase in ASD prevalence and the ubiquity of environmental pollutants, this review emphasizes the urgent need for further investigation and the adoption of comprehensive preventive measures.

Independent and combined effects of fine particulate matter and greenness on autism spectrum disorder symptoms: investigating sensitive periods of exposure in the early two years of life

Background

The impact of exposure to fine particulate matter (aerodynamic diameter ≤2.5 μm, PM2.5) and greenness during early two year of life on Autism Spectrum Disorder (ASD) symptoms, especially under the combined influence of the two factors, and the sensitive periods of exposure during the early life, remain underexplored.

Objective

This cross-sectional study recruited 108 children with ASD and aimed to quantify the independent and combined effects of PM2.5 and greenness exposure on ASD symptoms during the first two years of life.

Methods

We collected PM2.5 levels and Normalized Difference Vegetation Index (NDVI) values to reflect PM2.5 exposure and greenness levels, meanwhile, assessing ASD symptoms with the Autism Behavior Checklist (ABC) and its sub-scales (sensory, relating, stereotypic behavior, language, and social independence) scores. We identified six sensitive exposure periods: 6 months, 7-12 months, 13-18 months, 19-24 months after birth, and the first and second years after birth. We investigated the independent effects of PM2.5 and greenness on ASD symptoms using multiple linear or logistic regression for continuous or categorical symptom scores, and explored their additive interaction and mediation effects.

Results

Multiple linear models showed reduced total ABC, relating, and social independence scores with greenness exposure at 19-24 months after birth, while 7-12 months and first year exposures benefited social independence. Logistic models showed that PM2.5 exposures during 13-18 months after birth increased symptoms of stereotypic behavior, while low greenness exposure during 19-24 months after birth heightened the risk of social independence impairment. We found high levels of PM2.5 and low greenness during the 13-18 months after birth increased the risk of overall severity. Greenness exposure during 6 months after birth could mitigate the effects of PM2.5 exposures during 13-18 months.

Conclusion

Our findings underscore the importance of reducing air pollution and enhancing greenness to mitigate ASD symptoms.

Prenatal Exposure to Ambient Particulate Matter and Autism Spectrum Disorder in Children, a Case Control Study in France

A series of epidemiological studies conducted in the United States have consistently shown an increased risk of autism spectrum disorder (ASD) in children associated with pre- and postnatal exposure to ambient particulate matter (PM). In Europe, studies are scarce and results are inconsistent. We aimed to investigate the association between prenatal exposure to PM and the risk of ASD in France. ASD cases were participants from the ELENA cohort. Controls children from the ELFE cohort were matched by sex, year (± 2) and region of birth. Prenatal exposures to PM10 and to PM2.5 were estimated between 2008 and 2013 using innovative hybrid spatio-temporal models developed for France. Conditional logistic regression models adjusted for birth season, parent's age at the child birth and parental education level were run. We included 125 ASD cases and 500 controls. Prenatal PM2.5 and PM10 median (IQR) concentration estimates were respectively 16.3 (3.9) µg/m3 and 22.9 (6.6) µg/m3 in the whole sample. The conditional logistic regression models showed Odds Ratios (ORs) (Confidence Interval 95%) for ASD risk of 0.72 (0.52-1.01) and 0.84 (0.58-1.22) for an IQR increase in PM2.5 and PM10 prenatal levels, respectively. When restricting population of ASD cases to children born the same year of controls, ORs were 1.79 (0.80-4.01) and 2.23 (0.71-9.04), respectively. Our results did not show that prenatal exposures to PM2.5 and PM10 were associated with the risk of ASD in children in France.Trial Registration Number NCT02625116.

The association of particulate matter PM2.5 and nitrogen oxides from ambient air pollution and mental health of children and young adults- a systematic review

INTRODUCTION

The developing brain, especially vulnerable during neuroplastic phases, is influenced by environmental and genetic factors. Understanding the impacts of air pollution on children's and young adults' mental health is an emerging research field.

CONTENT

This review systematically examines the adverse associations of ambient air pollutants on mental health. A database search using Scopus, EMBASE, Global Health, and PsycINFO included articles from 2013 onwards, following PRISMA guidelines. Of the 787 identified articles, 62 met the inclusion criteria. Quality was assessed using the EPHPP tool, and Best Evidence Synthesis (BES) evaluated the findings.

SUMMARY

The review found 36 associations between ambient air pollutants and adverse mental health outcomes across seven life-course exposure periods. Strong evidence linked early-life PM2.5 and NO2 exposures to Autism Spectrum Disorder (ASD) and childhood exposures to Attention Deficit Hyperactivity Disorder (ADHD). Significant, though inconsistent, associations were found between air pollutants and cognitive impairments, anxiety, depression, self-harm, and other behavioral problems. The heterogeneity of exposure limits and lack of experimental studies hinder causal assessment.

OUTLOOK

Compelling evidence links early-life and childhood exposure to PM2.5 and NO2 with ASD and ADHD. These findings highlight the need for public health policy changes and further research to explore these associations comprehensively.

Preconception and gestational versus postnatal exposure to air pollutants and risk of autism spectrum disorder: a systematic review and meta-analysis

PURPOSE

The rising prevalence of ASD has prompted extensive research into potential environmental risk factors, with air pollution particularly emerging as a major concern. A systematic review and meta-analysis on the effect of air pollutants and time of exposure (particularly, PM2.5, PM10, NO2, and O3) and the risk of ASD was therefore performed.

METHODS

Following PRISMA guidelines and PROSPERO registration (Ref: CRD42023464592), a thorough literature search was conducted across multiple databases, including Scopus, PubMed/MEDLINE, Embase, PsycINFO, Web of Science, and Cochrane Library. The analysis included 27 studies encompassing 369,460 participants, 47,973 of whom were diagnosed with ASD.

RESULTS

Preconception exposure to air pollutants showed a protective trend for PM2.5, PM10, and O3 with a 10%, 5%, and 19% reduced risk of ASD, whereas NO2 had a 28% higher likelihood of ASD. During gestation, PM2.5 exposure increased ASD risk by 15%, with 13% and 9%, 25% and 7%, and 25% and 10% increases in ASD risk with PM2.5 and NO2 for the first, second, and third trimesters, respectively. In the first year of life, 20%, 8%, 33%, and 14% increases in risk were found for PM2.5, PM10, NO2, and O3, respectively, while such risk estimates increased to 179%, 60%, 12%, and 179% for the second year of life.

CONCLUSIONS

In this meta-analysis, the relationships between air pollutants and ASD risk revealed significant associations, particularly for PM2.5 and NO2. Exposure during preconception exhibited a protective trend, while postnatal exposure, particularly during the second year of life uncovered substantially higher ASD risk.

The contribution of environmental pollutants to the risk of autism and other neurodevelopmental disorders: A systematic review of case-control studies

Exposure to environmental pollutants, such as metals, pesticides, and air pollutants during early life, is a risk factor for neurodevelopmental disorders (NDDs), including Autism Spectrum Disorder (ASD). Our systematic review aimed to select and summarize more recent case-control studies that examined the association between prenatal and early postnatal exposure to environmental pollutants and NDDs. We searched five databases (Web of Science, PubMed, Embase, Scopus, Ovid), screened 2261 records, and included 24 eligible case-control studies. Meta-analyses were conducted on subgroups of at least three studies that shared both the outcome and the exposure. A noteworthy discovery from this literature review is the existence of non-linear or non-monotonic dose-response relationships between the exposure to certain metals and the risk of ASD. The meta-analysis revealed a significant association between exposure to particular matter (PM)10 during the first year of life and the risk of ASD. Overall, studies included in our systematic review indicate that exposure to several pollutants within the first three years of life was significantly associated with the risk of NDDs.

Fine particulate matter exposure and pediatric mental health outcomes: An integrative review

INTRODUCTION

Climate change is expected to worsen air pollution globally, which contributes to a multitude of negative health outcomes in humans.

AIM

The purpose of this integrative review is to examine the relationship between exposure to fine particulate matter (PM2.5 ) and mental health outcomes in children and adolescents.

METHODS

This review utilized Whittemore and Knafl's methodology for conducting an integrative review. After a thorough search of the literature, 17 articles were selected for this review and evaluated utilizing the Johns Hopkins Evidence Based Practice Appraisal Tool.

RESULTS

Of the 17 articles, all were quantitative observational study designs. The studies were then synthesized into four outcome themes. These themes included emergent and general psychiatric outcomes, neurodevelopmental disorders, stress and anxiety, and depression.

DISCUSSION

The strongest evidence supports a possible correlation between PM2.5 exposure and adolescent mental health outcomes, although there were some studies that contradicted these associations. While research on this topic is in its early stages, more needs to be conducted to determine causality with any of the associations presented to improve generalizability of the findings.

IMPLICATIONS FOR PRACTICE

Nurses must be aware of and part of the solution to address climate change and resulting air pollution, as it is a potentially significant threat to children's mental health in the 21st century.

Evidence for an association of prenatal exposure to particulate matter with clinical severity of Autism Spectrum Disorder

Early-life exposure to air pollutants, including ozone (O₃), particulate matter (PM_2.5 or PM₁₀, depending on diameter of particles), nitrogen dioxide (NO₂) and sulfur dioxide (SO₂) has been suggested to contribute to the etiology of Autism Spectrum Disorder (ASD). In this study, we used air quality monitoring data to examine whether mothers of children with ASD were exposed to high levels of air pollutants during critical periods of pregnancy, and if higher exposure levels may lead to a higher clinical severity in their offspring. We used public data from the Portuguese Environment Agency to estimate exposure to these pollutants during the first, second and third trimesters of pregnancy, full pregnancy and first year of life of the child, for 217 subjects with ASD born between 2003 and 2016. These subjects were stratified in two subgroups according to clinical severity, as defined by the Autism Diagnostic Observational Schedule (ADOS). For all time periods, the average levels of PM_2.5, PM₁₀ and NO₂ to which the subjects were exposed were within the admissible levels defined by the European Union. However, a fraction of these subjects showed exposure to levels of PM_2.5 and PM₁₀ above the admissible threshold. A higher clinical severity was associated with higher exposure to PM_2.5 (p = 0.001), NO₂ (p = 0.011) and PM₁₀ (p = 0.041) during the first trimester of pregnancy, when compared with milder clinical severity. After logistic regression, associations with higher clinical severity were identified for PM_2.5 exposure during the first trimester (p = 0.002; OR = 1.14, 95%CI: 1.05-1.23) and full pregnancy (p = 0.04; OR = 1.07, 95%CI: 1.00-1.15) and for PM₁₀ (p = 0.02; OR = 1.07, 95%CI: 1.01-1.14) exposure during the third trimester. Exposure to PM is known to elicit neuropathological mechanisms associated with ASD, including neuroinflammation, mitochondrial disruptions, oxidative stress and epigenetic changes. These results offer new insights on the impact of early-life exposure to PM in ASD clinical severity.

Inflammation and the Potential Implication of Macrophage-Microglia Polarization in Human ASD: An Overview

Autism spectrum disorder (ASD) is a heterogeneous collection of neurodevelopmental disorders, difficult to diagnose and currently lacking treatment options. The possibility of finding reliable biomarkers useful for early identification would offer the opportunity to intervene with treatment strategies to improve the life quality of ASD patients. To date, there are many recognized risk factors for the development of ASD, both genetic and non-genetic. Although genetic and epigenetic factors may play a critical role, the extent of their contribution to ASD risk is still under study. On the other hand, non-genetic risk factors include pollution, nutrition, infection, psychological states, and lifestyle, all together known as the exposome, which impacts the mother's and fetus's life, especially during pregnancy. Pathogenic and non-pathogenic maternal immune activation (MIA) and autoimmune diseases can cause various alterations in the fetal environment, also contributing to the etiology of ASD in offspring. Activation of monocytes, macrophages, mast cells and microglia and high production of pro-inflammatory cytokines are indeed the cause of neuroinflammation, and the latter is involved in ASD's onset and development. In this review, we focused on non-genetic risk factors, especially on the connection between inflammation, macrophage polarization and ASD syndrome, MIA, and the involvement of microglia.

Particulate matter exposure during pregnancy and infancy and risks of autism spectrum disorder in children: A systematic review and meta-analysis

PURPOSE

This meta-analysis aimed to clarify the relationship between particulate matter (PM) and autism spectrum disorder (ASD) in detail.

METHODS

A systematic literature search was performed using eight databases before April 9, 2022. The estimated effects were combined separately according to the PM type. Subgroup analyses were conducted in terms of the study design type, study location, exposure window, birth year, and sex.

RESULTS

PM_2.5 was associated with an increased risk of ASD, while PM₁₀ was not. PMc, PM₁, and diesel particulate matter (DPM) were also associated with an increased risk of ASD. Specifically, a 10 μg/m³ increase in PM_2.5 was associated with a 1.337-fold increased risk of ASD in children, and a 10 μg/m³ increase in PMc and PM₁ may increase the risk of ASD by 1.062 and 3.643 times, respectively. PM_2.5 exposure may increase the risk of ASD in boys. Exposure to PMc might increase the risk of ASD in children born after the year 2000. The combined results of different PM differed between studies with continuous and non-continuous data for different study design type, study location, and birth year. The sensitive window for PM_2.5 exposure to increase the risk of ASD may be from the first, second, and third trimesters to the first year of the postnatal period. Exposure to PMc during pregnancy was significantly associated with ASD.

CONCLUSION

Exposure to PM_2.5 may increase the risk of ASD in boys. Exposure to PM_2.5 during the first, second, and third trimesters and postnatally increased the risk of ASD.

The epidemiological evidence linking exposure to ambient particulate matter with neurodevelopmental disorders: A systematic review and meta-analysis

BACKGROUND

There has been increasing attention on the associations between ambient particulate matter (PM) in early-life and neurodevelopmental disorders (NDDs). However, the associations remained unclear when considering different types of NDDs and different sizes of PM, and vulnerable exposure windows during early-life were not identified yet.

OBJECTIVE

To synthesize the published literature on the associations between ambient particulate matter (PM) and risk of different types of neurodevelopmental disorders (NDDs) in a systematic review and meta-analysis.

METHODS

A systematic search of Medline, Embase, PubMed, Cochrane Library, and Web of Science was performed from inception through 24 January 2022. Two reviewers conducted the study selection, data extraction, and quality appraisal. A random-effects model was used for meta-analyses with two quality-of-evidence assessments (the Grading of Recommendations Assessment, Development, and Evaluation system and the best evidence synthesis system).

RESULTS

A total of 6554 articles were screened, of which 31 were included in the review, and 20 provided adequate data for meta-analyses. Exposures to particulate matter of 2.5 μm or less (PM_2.5) during prenatal periods (OR, 1.32 [95%CI, 1.03-1.69]), the first year after birth (OR, 1.62 [95%CI, 1.22-2.15]) and the second year after birth (OR, 3.13 [95%CI, 1.47-6.67]) were associated with increased risk of autism spectrum disorders (ASD) in children. The quality of evidence for these associations during early postnatal periods was somewhat moderate with limited studies. We found inconsistent evidence when considering other types of NDDs and different sizes of PM.

CONCLUSIONS AND RELEVANCE

Current evidence indicated that there might be an association between PM_2.5 exposure and higher risk of ASD, and early postnatal periods appeared to be the critical exposure window. High-quality studies are needed to assess the evidence for other types of NDDs.

Influence of the Aryl Hydrocarbon Receptor Activating Environmental Pollutants on Autism Spectrum Disorder

Autism spectrum disorder (ASD) is an umbrella term that includes many different disorders that affect the development, communication, and behavior of an individual. Prevalence of ASD has risen exponentially in the past couple of decades. ASD has a complex etiology and traditionally recognized risk factors only account for a small percentage of incidence of the disorder. Recent studies have examined factors beyond the conventional risk factors (e.g., environmental pollution). There has been an increase in air pollution since the beginning of industrialization. Most environmental pollutants cause toxicities through activation of several cellular receptors, such as the aryl hydrocarbon receptor (AhR)/cytochrome P450 (CYPs) pathway. There is little research on the involvement of AhR in contributing to ASD. Although a few reviews have discussed and addressed the link between increased prevalence of ASD and exposure to environmental pollutants, the mechanism governing this effect, specifically the role of AhR in ASD development and the molecular mechanisms involved, have not been discussed or reviewed before. This article reviews the state of knowledge regarding the impact of the AhR/CYP pathway modulation upon exposure to environmental pollutants on ASD risk, incidence, and development. It also explores the molecular mechanisms involved, such as epigenesis and polymorphism. In addition, the review explores possible new AhR-mediated mechanisms of several drugs used for treatment of ASD, such as sulforaphane, resveratrol, haloperidol, and metformin.