Association of early-life exposure to household gas appliances and indoor nitrogen dioxide with cognition and attention behavior in preschoolers

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.

Exposure to PM10, PM2.5, and NO2 and gross motor function in children: a systematic review and meta-analysis

Air pollution exposure has been related to negative gross motor development in children. However, there is currently a lack of conclusive evidence for such a relationship. We carried out a systematic review and meta-analysis using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria to examine whether exposure to air pollution has an impact on children's gross motor development. Of the 9746 papers found, 7 studies examined the impact of air pollutant characteristics, such as PM_2.5, PM₁₀, and NO₂, on children's gross motor development. The results of the study reveal a significant association between air pollutants and an increased likelihood of negative gross motor development. PM₁₀ was discovered to be considerably riskier for children's gross motor development (effect: - 1.83, 95% CI: - 3.04, - 0.62, p value = 0.002). Additionally, NO₂ exhibited indications of a tendency to be connected to a detrimental impact on children's gross motor development (effect - 0.18, 95% CI: - 0.42, 0.07, p value = 0.097).  Conclusion: Our study indicates that exposure to PM₁₀, PM_2.5, and NO₂, especially PM_2.5 and PM₁₀, is negatively associated with children's gross motor development. However, further research is required to determine how exposure to prenatal air pollution affects children's gross motor development. What is Known - What is New: • In this study, we provide an overview of emerging data related to PM10, PM2.5, and NO2 exposure in child development, especially on the gross motor function that continues to emerge, and key findings are highlighted. • Additionally, we summarize the evidence on the underlying effect of air pollution on gross motor function from human studies.. • Overall, we emphasize that evidence from human studies is critical in suggesting detrimental child health outcomes of an action to promote preventive strategies that will effectively protect children's health..

Chronic exposure to indoor air pollutants in association with attention-deficit/hyperactivity disorder symptoms in Chinese schoolchildren: A cross-sectional study

BACKGROUND

While increasing studies confirmed the adverse effects of indoor air pollution (IAP) on cardiopulmonary systems, less is known about the impact of IAP on child's brain.

OBJECTIVE

To explore the associations between multiple indoor air pollutants exposures and attention-deficit/hyperactivity disorder (ADHD) symptoms in Chinese schoolchildren.

METHODS

We invited 8630 individuals aged 6-12 years from an ongoing school-based cohort study across Guangzhou from April to May 2019. There are 7495 and 7245 children were respectively evaluated on the parent- and teacher-rated Conner's Rating Scale-Revised, and 7087 children were assessed on both versions. Indoor air pollutants exposures including cooking oil fumes, incense burning, home renovation, and secondhand smoke, were measured using a questionnaire reported by parents and children, and further converted into an index. Generalized linear mixed-effects models were performed to evaluate the associations between indoor air pollutants exposures and ADHD index and the presence of ADHD symptoms.

RESULTS

As reported by parents, 321 (4.3%) children had ADHD symptoms. Each of the four pollutants was positively associated with higher ADHD index and higher odds of ADHD symptoms. Children exposed to 1, 2, and ≥ 3 types of indoor air pollutants had higher ADHD index and higher odds of ADHD symptoms than those non-exposed children. For parent-reported ADHD symptoms, the odds ratios ranged from 1.24 [95% confidence interval (CI): 0.92-1.67] to 2.73 (95% CI: 1.86-4.01). These associations were consistent in parent- and teacher-reported ADHD symptoms, and the combination of both.

CONCLUSION

Indoor air pollutants exposures were positively associated with higher prevalence of children's ADHD symptoms assessed by whether parents or teachers.

Environmental pollution and attention deficit hyperactivity disorder: A meta-analysis of cohort studies

There is already knowledge of the extensive risk factors for attention deficit hyperactivity disorder (ADHD) and recent studies suggest that environmental pollution may contribute to an increase in the incidence of the disorder. The aim of our study was to perform a systematic review and meta-analysis of the risk of ADHD in people younger than 18 years old after exposure to environmental pollution. We searched the MEDLINE, Embase, SciELO, CINAHL, LILACS, Cochrane Central, and Web of Science databases and investigated the grey literature from inception until May 31, 2021. All cohort studies that provided data on exposure to environmental pollutants and ADHD in children and adolescents aged from zero to 18 years old were included. Two reviewers independently selected the studies and applied the quality criteria. If there was a divergence, a third reviewer contributed to the final decision. For the meta-analysis, risk ratios and their confidence intervals were calculated with the MetaXL 5.3 program, using the random effects model. In total, 21 articles were included in this systematic review, and 18 studies met the criteria for the meta-analysis, involving 134,619 participants. The meta-analysis suggested that children exposed to higher levels of heavy metal (RR: 2.41, 95% CI: 1.49-3.90), with low heterogeneity (I² = 39%), and lead (RR: 2.37, 95% CI: 1.28-4.40), with moderate heterogeneity (I² = 54%), are at greater risk of developing ADHD than those exposed to lower levels. This meta-analysis suggests that children exposed to higher levels of lead and heavy metal pollution are at greater risk of developing ADHD than those exposed to lower levels.

Maternal exposure to cooking oil fumes during pregnancy and autistic-like behaviors in Chinese preschoolers

There is growing evidence that cooking oil fumes (COFs) are harmful indoor air pollutants. However, there is a dearth of research investigating whether maternal COFs exposure during pregnancy may affect children's autistic-like behaviors in China. This study aimed to explore this association, and examine the effects of different cooking fuels and ventilation methods used by mothers on the presence of autistic-like behaviors. This study analyzed the survey data of the Longhua Child Cohort Study in 2017 with a total of 62,372 mothers enrolled in this study. A self-administrative questionnaire was used to collect information on socio-demographic characteristics, cooking habits during pregnancy, and autistic-like behaviors (measured using the Autism Behavior Checklist). After adjusting for potential confounders, the results showed that compared with children whose mothers never cooked during pregnancy, children whose mothers cooked sometimes, often, always during pregnancy had the higher risk of autistic-like behaviors. As the amounts of COFs exposed to and the frequency of cooking during pregnancy increased, the risk of a child's autistic-like behaviors also increased. Mothers using natural gas as cooking fuels had a lower risk of their child having autistic-like behaviors, compared with mothers using coal or other cooking fuels. Furthermore, pregnant women using ventilation measures during cooking significantly decreased likelihood of the presence of autistic-like behaviors in their children. These results suggest that maternal exposure to COFs during pregnancy may increase the likelihood of the presence of autistic-like behaviors in offspring. These findings support a recommendation that pregnant women should avoid exposure to COFs and use clean fuels and ventilation equipment in kitchens to reduce the risk of autistic-like behaviors in children.

Association between exposure to air pollutants and attention-deficit hyperactivity disorder (ADHD) in children: a systematic review and meta-analysis

Recent studies have reached mixed conclusions regarding the association between exposure to air pollutants and attention-deficit hyperactivity disorder (ADHD). We performed systematic review and meta-analysis to determine whether air pollutants were risk factors for the development of ADHD in children. We systematically searched databases for all relevant studies up to 2 July 2019. Together, the studies indicated that exposure to PAHs (risk ratio (RR): 0.98, 95% confidence interval (CI): 0.82-1.17), NOx (RR: 1.04, 95% CI: 0.94-1.15), and PM (RR: 1.11, 95% CI: 0.93-1.33) did not have any material relationship with an increased risk of ADHD. Heterogeneity of study data was low (I²: 2.7%, P = 0.409) for studies examining PAHs, but was substantial for NOx and PM (I²: 68.4%, P = 0.007 and I²: 60.1%, P = 0.014, respectively). However, these results should be interpreted with caution since the number of epidemiological studies investigating this issue were limited.

Association between Exposure to Particulate Matter during Pregnancy and Multidimensional Development in School-Age Children: A Cross-Sectional Study in Italy

Air pollutants can potentially affect the development of children. However, data on the effect of exposure to air pollution during pregnancy and developmental outcomes in school children are rare. We investigated the link between prenatal exposure to particulate matters smaller than 10 microns (PM₁₀) and the development of school-age children in multiple domains. Cross-sectional data were collected in Italy between 2013 and 2014. Children aged between 5 and 8 years (n = 1187) were assessed on cognitive, communication, socio-emotional, adaptive, and motor developmental domains using the Developmental Profile 3 questionnaire. The monthly average concentration of PM₁₀ during the entire fetal period was linked to the municipality of residence of the children. The increase in the prenatal PM₁₀ was associated with a decrease in the cognitive score during the second (+13.2 µg/m³ PM₁₀ increase: −0.30 points; 95%CI: −0.12–−0.48) and third trimesters of pregnancy (−0.31 points; 95%CI: −0.11–−0.50). The communicative domain was also negatively influenced by PM₁₀ increases in the second trimester. The development of cognitive and communicative abilities of children was negatively associated with the exposure to PM₁₀ during the period of fetal development, confirming that exposure to air pollution during pregnancy can potentially hinder the development of the brain.

In vitro and in vitro toxicity study of diesel exhaust particles using BEAS-2B cell line and the nematode Caenorhabditis elegans as biological models

It is well accepted that diesel exhaust particles (DEPs) are highly associated with improper function of organ systems. In this study, DEP toxicity was performed by using in vitro human BEAS-2B cell line and in vivo animal model, namely, Caenorhabditis elegans (C. elegans). The potential toxicity of DEP was assessed by the apical endpoints of BEAS-2B cell line and reflections of C. elegans under exposure scenarios of 0~50 μg mL^-1 DEP. With the increase of DEP exposure concentration, microscopic accumulations in the cytoplasm of cell line and intestine of C. elegans were observed. Such invasion of DEP impaired the behaviors of C. elegans as well as its un-exposed offspring and caused significant impeded locomotion. Moreover, the disorders of dopaminergic function were observed simultaneously under DEP exposure, specifically manifested by the decreased transcriptional expression of dat-1. The stress responses instructed by the expression of hsp-16.2 were also increased sharply in TJ375 strain of C. elegans at DEP concentrations of 1 and 10 μg mL^-1. In the case of cellular reactions to DEP exposure, the injuries of membrane integrity and the decreased viability of cell line were simultaneously identified, and reactive oxygen species (ROS), damaged DNA fragment, and upregulated apoptosis were monotonically elevated in cell lines with the increase of DEP concentrations. This study provided a systematic insight into toxicity of DEP both in vivo and vitro, demonstrating that DEP exposure could disturb the stability of cell system and further threat the stability of organism.

Air Pollution during Pregnancy and Childhood Autism Spectrum Disorder in Taiwan

Air pollutants have been linked to some diseases in humans, but their effects on the nervous system were less frequently evaluated. Autism spectrum disorder (ASD) is a group of neurondevelopmental disorders of which the etiology is still unknown. We conducted a study in Taiwan to evaluate the possible associations between prenatal exposure to air pollutants and ASD. From a random sample of one million people in the National Insurance Research Database, we identified all the infants born between 1996 and 2000. We followed them till the end of 2013 and identified cases of ASD. We traced back the mothers’ residence and assessed the exposure to air pollutants using the data obtained from the air quality monitoring database maintained by the government, which included ozone (O₃), carbon monoxide (CO), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), and particulate matters with diameter less than 10 µm (PM₁₀). Cox proportional hazard models were constructed to evaluate the associations between childhood ASD and exposures to the pollutants in the three trimesters and the whole gestation. We identified a total of 63,376 newborns and included 62,919 as the study cohort. After adjusting for other risk factors, we observed trimester-specific associations between levels of CO, NO₂, and PM₁₀ and the risk of childhood ASD. An increase of 1 ppm of CO in the first, second, and third trimester was associated with a hazard ratio (HR) of 1.93 (95% confidence interval [CI]: 1.55–2.39), 1.77 (95%CI: 1.41–2.22), and 1.75 (95%CI: 1.39–2.21), respectively. An increase of 10 ppb in the level of NO₂ in the first, second, and third trimester was associated with an HR of 1.39 (95%CI: 1.22–1.58), 1.25 (95%CI: 1.10–1.42), and 1.18 (95%CI: 1.03–1.34), respectively. In conclusion, we found that exposures to CO and NO₂ in all three trimesters were associated with increased risks of developing ASD.

Early-life environmental exposure determinants of child behavior in Europe: A longitudinal, population-based study

BACKGROUND

Environmental exposures in early life influence the development of behavioral outcomes in children, but research has not considered multiple exposures. We therefore aimed to investigate the impact of a broad spectrum of pre- and postnatal environmental exposures on child behavior.

METHODS AND FINDINGS

We used data from the HELIX (Human Early Life Exposome) project, which was based on six longitudinal population-based birth cohorts in Europe. At 6-11 years, children underwent a follow-up to characterize their exposures and assess behavioral problems. We measured 88 prenatal and 123 childhood environmental factors, including outdoor, indoor, chemical, lifestyle and social exposures. Parent-reported behavioral problems included (1) internalizing, (2) externalizing scores, using the child behavior checklist (CBCL), and (3) the Conner's Attention Deficit Hyperactivity Disorder (ADHD) index, all outcomes being discrete raw counts. We applied LASSO penalized negative binomial regression models to identify which exposures were associated with the outcomes, while adjusting for co-exposures. In the 1287 children (mean age 8.0 years), 7.3% had a neuropsychiatric medical diagnosis according to parent's reports. During pregnancy, smoking and car traffic showing the strongest associations (e.g. smoking with ADHD index, aMR:1.31 [1.09; 1.59]) among the 13 exposures selected by LASSO, for at least one of the outcomes. During childhood, longer sleep duration, healthy diet and higher family social capital were associated with reduced scores whereas higher exposure to lead, copper, indoor air pollution, unhealthy diet were associated with increased scores. Unexpected decreases in behavioral scores were found with polychlorinated biphenyls (PCBs) and organophosphate (OP) pesticides.

CONCLUSIONS

Our systematic exposome approach identified several environmental contaminants and healthy lifestyle habits that may influence behavioral problems in children. Modifying environmental exposures early in life may limit lifetime mental health risk.

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.

Female vulnerability to the effects of smoking on health outcomes in older people

Cigarette smoking is among the leading risk factors for mortality and morbidity. While men have a higher smoking prevalence, mechanistic experiments suggest that women are at higher risk for health problems due to smoking. Moreover, the comparison of smoking effects on multiple conditions and mortality for men and women has not yet been done in a population-based group with race/ethnic diversity. We used proportional hazards models and restricted mean survival time to assess differences in smoking effects by sex for multiple health outcomes using data from the U.S. Health and Retirement Study (HRS), a population-representative cohort of individuals aged 50+ (n = 22,708, 1992-2014). Men had experienced more smoking pack-years than women (22.0 vs 15.6 average pack-years). Age of death, onset of lung disorders, heart disease, stroke, and cancer showed dose-dependent effects of smoking for both sexes. Among heavy smokers (>28 pack-years) women had higher risk of earlier age of death (HR = 1.3, 95%CI:1.03-1.65) and stroke (HR = 1.37, 95%CI:1.02-1.83). Risk of cancer and heart disease did not differ by sex for smokers. Women had earlier age of onset for lung disorders (HR = 2.83, 95%CI:1.74-4.6), but men risk due to smoking were higher (Smoking-Sex interaction P<0.02) than women. Passive smoke exposure increased risk of earlier heart disease (HR = 1.33, 95%CI:1.07-1.65) and stroke (HR:1.54, 95%CI:1.07-2.22) for non-smokers, mainly in men. Smoking cessation after 15 years partially attenuated the deleterious smoking effects for all health outcomes. In sum, our results suggest that women are more vulnerable to ever smoking for earlier death and risk of stroke, but less vulnerable for lung disorders. From an epidemiological perspective, sex differences in smoking effects are important considerations that could underlie sex differences in health outcomes. These findings also encourage future mechanistic experiments to resolve potential mechanisms of sex-specific cigarette smoke toxicity.

Prenatal NO2 exposure and neurodevelopmental disorders in offspring mice: Transcriptomics reveals sex-dependent changes in cerebral gene expression

BACKGROUND

Early-life exposure to nitrogen dioxide (NO₂) is associated with an increased risk of developing a neurodevelopmental disorder during childhood or later in life.

OBJECTIVES

We investigated whether prenatal NO₂ inhalation causes neurodevelopmental abnormalities and cognitive deficits in weanling offspring without subsequent postnatal NO₂ exposure and how this prenatal exposure contributes to postnatal consequences.

METHODS

Pregnant C57BL/6 mice were exposed to air or NO₂ (2.5 ppm, 5 h/day) throughout gestation, and the offspring were sacrificed on postnatal days (PNDs) 1, 7, 14 and 21. We determined the mRNA profiles of different postnatal developmental windows, detected the long noncoding RNA (lncRNA) profiles and cognitive function in weanling offspring, and analyzed the effects of hub lncRNAs on differentially expressed genes (DEGs).

RESULTS

Prenatal NO₂ inhalation significantly impaired cognitive function in the weanling male, but not female, offspring. The male-specific response was coupled with abnormal neuropathologies and transcriptional profiles in the cortex during different postnatal developmental windows. Consistently, Gene Ontology (GO) analysis of the DEGs revealed persistent disruptions in neurodevelopment-associated biological processes and cellular components in the male offspring, and Apolipoprotein E (ApoE) was one of key factors contributing to prenatal exposure-induced male-specific neurological dysfunction. In addition, distinct sex-dependent lncRNA expression was identified in the weanling offspring, and metastasis-associated lung adenocarcinoma transcript 1 (Malat1) acted as a hub lncRNA and was coexpressed with most coding genes in the lncRNA-mRNA coexpressed pairs in the male offspring. Importantly, lncRNA Malat1 expression was elevated, and Malat1 modulated ApoE expression through NF-κB activation during this process.

CONCLUSIONS

Prenatal NO₂ exposure is related to sex-dependent neurocognitive deficits and transcriptomic profile changes in the cortices of the prenatally exposed offspring. Male-specific neurological dysfunction is associated with the constant alteration of genes during postnatal neurodevelopment and their transcriptional modulation by hub lncRNAs.

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.

A comprehensive analysis of cooking solutions co-benefits at household level: Healthy lives and well-being, gender and climate change

Three billion people (>40% of the world's population) lack access to clean cooking solutions, including 2.5 billion people that still rely on the traditional use of biomass for cooking. In urban contexts, the rate of access to clean cooking solutions is normally higher than in rural contexts due to greater availability of these solutions. The relevance of providing access to clean cooking solutions (SDG 7) is linked to several associated co-benefits that contribute to a wide range of Sustainable Development Goals (SDGs). Therefore, this paper shows a comprehensive analysis of multiple co-benefits of a clean cooking solution intervention. Health (SDG 3), gender (SDG 5) and climate change (SDG 13) co-benefits were analysed and compared through a cost-benefit analysis using a comprehensive approach in a case study in the Casamance Natural Subregion, located in Western Africa. The most important co-benefits were related to gender (SDG 5), representing 60-97% of the total economic benefits. Climate change co-benefits (SDG 13) were also relevant, representing 3-40% of the total economic benefits. Health co-benefits (SDG 3) were very limited for this case study, representing <1% of the total economic benefits. Considering these results, implications for urban settings were discussed in the light of the "making the available clean" or "making the clean available" strategies.

Maternal cooking during pregnancy may increase hyperactive behaviors among children aged at around 3 years old

Cooking is one of the main sources of indoor air pollution in China. Given emerging evidence of a link between air pollutants and neurodevelopmental delays, we examined whether maternal experiences with cooking during gestation might increase their child's hyperactivity at 3 years of age. The participants involved 45 518 mothers of children who were newly enrolled at kindergarten in the Longhua District of Shenzhen from 2015 to 2017. The results show that maternal exposure to cooking fumes during pregnancy was related to an increased risk of their offspring having hyperactivity behaviors at the age of 3 years. Compared with pregnant mothers who never cooked, pregnant mothers who cooked sometimes, often, or always had children who showed a significantly higher hyperactivity risk. Households using cooking fuels such as coal, gas during the mothers' pregnancy, exhibited more hyperactivity behaviors in the young child when compared to those using electricity for cooking. In addition, poor ventilation during cooking, while mothers were pregnant, was found to be a significant risk factor for clinical levels of the offspring's hyperactive behaviors. Furthermore, the positive association with maternal cooking during pregnancy and their offsprings' hyperactivity was relatively consistent across strata defined by social class, education, and other covariates.

Air Pollution (Particulate Matter) Exposure and Associations with Depression, Anxiety, Bipolar, Psychosis and Suicide Risk: A Systematic Review and Meta-Analysis

BACKGROUND

Particulate air pollution's physical health effects are well known, but associations between particulate matter (PM) exposure and mental illness have not yet been established. However, there is increasing interest in emerging evidence supporting a possible etiological link.

OBJECTIVES

This systematic review aims to provide a comprehensive overview and synthesis of the epidemiological literature to date by investigating quantitative associations between PM and multiple adverse mental health outcomes (depression, anxiety, bipolar disorder, psychosis, or suicide).

METHODS

We undertook a systematic review and meta-analysis. We searched Medline, PsycINFO, and EMBASE from January 1974 to September 2017 for English-language human observational studies reporting quantitative associations between exposure to PM < 1.0 μ m in aerodynamic diameter (ultrafine particles) and PM < 2.5 and < 10 μ m in aerodynamic diameter (PM 2.5 and PM 10 , respectively) and the above psychiatric outcomes. We extracted data, appraised study quality using a published quality assessment tool, summarized methodological approaches, and conducted meta-analyses where appropriate.

RESULTS

Of 1,826 citations identified, 22 met our overall inclusion criteria, and we included 9 in our primary meta-analyses. In our meta-analysis of associations between long-term (> 6   months ) PM 2.5 exposure and depression (n = 5 studies), the pooled odds ratio was 1.102 per 10 - μ g / m 3 PM 2.5 increase (95% CI: 1.023, 1.189; I 2 = 0.00 % ). Two of the included studies investigating associations between long-term PM 2.5 exposure and anxiety also reported statistically significant positive associations, and we found a statistically significant association between short-term PM 10 exposure and suicide in meta-analysis at a 0-2 d cumulative exposure lag.

DISCUSSION

Our findings support the hypothesis of an association between long-term PM 2.5 exposure and depression, as well as supporting hypotheses of possible associations between long-term PM 2.5 exposure and anxiety and between short-term PM 10 exposure and suicide. The limited literature and methodological challenges in this field, including heterogeneous outcome definitions, exposure assessment, and residual confounding, suggest further high-quality studies are warranted to investigate potentially causal associations between air pollution and poor mental health. https://doi.org/10.1289/EHP4595.

Association between prenatal exposure to household inhalants exposure and ADHD-like behaviors at around 3 years of age: Findings from Shenzhen Longhua Child Cohort Study

BACKGROUND

Prenatal exposure to air pollutants has been suggested as a possible etiologic factor for the occurrence of ADHD or ADHD-like behaviors. But we still lack a comprehensive assessment of household air pollutants exposure on the development of ADHD-like behaviors during childhood.

OBJECT

We aimed to assess whether prenatal household inhalants exposure is associated with preschoolers' ADHD-like behaviors in a nonclinical population.

METHODS

This study used the baseline data of the Longhua Child Cohort Study. During 2015-2017, we recruited 42,983 mothers and their kindergarten-aged children who enrolled at kindergarten in the Longhua district of Shenzhen, to obtain the demographic data and relevant exposure information through self-administrated questionnaire survey. The source of prenatal household inhalants exposure include cooking fumes, environmental tobacco smoke, mosqutio coils, home renovated and indoor burning incense. Logistic and censored least absolute deviations (CLAD) models were used to reveal the association between prenatal exposure to household air pollutants and hyperactive behaviors in child.

RESULTS

We found that exposure to five types of household inhalants during pregnancy were independently associated with an increased risk of child hyperactive behaviors. Moreover, we observed a significant interaction between exposure to environmental tobacco smoke and cooking fumes during gestation on child hyperactive behaviors in CLAD models. We also found a significant joint effect between burning mosquito coils and incense during gestation for child hyperactive behaviors risk both in CLAD and Logistic models. Furthermore, a household inhalants exposure index was used to demonstrate a dose-response relationship between the cumulative effect of exposure to the five household air pollutants and child hyperactivity.

CONCLUSIONS

Our results suggest that prenatal exposure to different household inhalants might increase the risk of children's hyperactive behaviors at around 3 years of age with the presence of interaction effects between some inhalants.

Reducing Inequities in Early Childhood Mental Health: How Might the Neighborhood Built Environment Help Close the Gap? A Systematic Search and Critical Review

BACKGROUND

Optimal mental health in early childhood is key to later mental health, physical health, education, and social outcomes; yet, children facing disadvantage tend to have worse mental health and fewer opportunities to develop this foundation. An emerging body of research shows that neighborhoods provide important opportunities for the development of children's mental health. Synthesizing this evidence can advance understandings of the features of the neighborhood built environment (e.g., housing, parks) that (1) promote optimal mental health in childhood and (2) reduce mental health inequities.

METHODS

We systematically searched and critically reviewed the international quantitative literature investigating associations between the neighborhood built environment and young children's mental health.

RESULTS

14 articles met inclusion criteria; most examined nature or public open space. Studies tended to find greater access to or quantity of neighborhood nature or public open space were associated with better mental health. Significant gaps included a lack of studies investigating social infrastructure, and few studies examined how the built environment related to positive mental health (i.e., functioning, rather than problems).

CONCLUSIONS

Current evidence suggests there is some relationship, but additional research is needed that addresses these gaps and examines differences in associations between child subgroups (e.g., diverse socioeconomic backgrounds).

Perinatal Exposure to Environmental Endocrine Disruptors in the Emergence of Neurodevelopmental Psychiatric Diseases: A Systematic Review

Background: Exposure to endocrine disruptors is on the rise, with new compounds regularly incriminated. In animals and humans, this exposure during critical developmental windows has been associated with various developmental abnormalities, including the emergence of psychiatric disorders. We aimed to review the association between perinatal endocrine disruptor exposure and neurodevelopmental disorders in humans, focusing on cognitive and psychiatric disorders. Methods: We performed a systematic review with key words referring to the fields of neurodevelopment and endocrine disruptors. We reviewed 896 titles, choosing studies on the basis of titles and abstracts. We searched through the methodology sections to find perinatal exposure and neurodevelopmental disorders, following the categories indicated in the Diagnostic and Statistic Manual of Mental Disorders (5^th edition). References in some studies brought us to a total of 47 studies included here. Results: Convergent studies report an association between exposure to endocrine disruptors and autism spectrum disorder, attention-deficit hyperactivity disorder, global developmental delay, intellectual disability, communication disorders and unspecified neurodevelopmental disorders. Conclusion: Sufficient data exist to report that exposure to some endocrine disruptors is a risk factor for the emergence of neurodevelopmental disorders. Studying endocrine disruptor exposure in humans is still associated with some limits that are difficult to overcome.

Exposure to environmental toxicants and young children's cognitive and social development

Background Understanding the role of environmental toxicant exposure on children's development is an important area of inquiry in order to better understand contextual factors that shape development and ultimately school readiness among young children. There is evidence suggesting negative links between exposure to environmental toxicants and negative physical health outcomes (i.e. asthma, allergies) in children. However, research on children's exposure to environmental toxicants and other developmental outcomes (cognitive, socioemotional) is limited. Objectives The goal of the current review was to assess the existing literature on the links between environmental toxicants (excluding heavy metals) and children's cognitive, socioemotional, and behavioral development among young children. Methods This literature review highlights research on environmental toxicants (i.e. pesticide exposure, bisphenol A, polycyclic aromatic hydrocarbons, tobacco smoke, polychlorinated biphenyls, flame retardants, phthalates and gas pollutions) and children's development across multiple domains. Results The results highlight the potential risk of exposure to multiple environmental toxicants for young children's cognitive and socioemotional development. Discussion Discussion will focus on the role of environmental toxicants in the cognitive and socioemotional development of young children, while highlighting gaps in the existing literature.

Association Between Air Pollution Exposure, Cognitive and Adaptive Function, and ASD Severity Among Children with Autism Spectrum Disorder

Prenatal exposure to air pollution has been associated with autism spectrum disorder (ASD) risk but no study has examined associations with ASD severity or functioning. Cognitive ability, adaptive functioning, and ASD severity were assessed in 327 children with ASD from the Childhood Autism Risks from Genetics and the Environment study using the Mullen Scales of Early Learning (MSEL), the Vineland Adaptive Behavior Scales (VABS), and the Autism Diagnostic Observation Schedule calibrated severity score. Estimates of nitrogen dioxide (NO₂), particulate matter (PM_2.5 and PM₁₀), ozone, and near-roadway air pollution were assigned to each trimester of pregnancy and first year of life. Increasing prenatal and first year NO₂ exposures were associated with decreased MSEL and VABS scores. Increasing PM₁₀ exposure in the third trimester was paradoxically associated with improved performance on the VABS. ASD severity was not associated with air pollution exposure.

Air Pollution Exposure During Pregnancy and Symptoms of Attention Deficit and Hyperactivity Disorder in Children in Europe

BACKGROUND

Exposure to air pollution during pregnancy may increase attention-deficit/hyperactivity disorder (ADHD) symptoms in children, but findings have been inconsistent. We aimed to study this association in a collaborative study of eight European population-based birth/child cohorts, including 29,127 mother-child pairs.

METHODS

Air pollution concentrations (nitrogen dioxide [NO2] and particulate matter [PM]) were estimated at the birth address by land-use regression models based on monitoring campaigns performed between 2008 and 2011. We extrapolated concentrations back in time to exact pregnancy periods. Teachers or parents assessed ADHD symptoms at 3-10 years of age. We classified children as having ADHD symptoms within the borderline/clinical range and within the clinical range using validated cutoffs. We combined all adjusted area-specific effect estimates using random-effects meta-analysis and multiple imputations and applied inverse probability-weighting methods to correct for loss to follow-up.

RESULTS

We classified a total of 2,801 children as having ADHD symptoms within the borderline/clinical range, and 1,590 within the clinical range. Exposure to air pollution during pregnancy was not associated with a higher odds of ADHD symptoms within the borderline/clinical range (e.g., adjusted odds ratio [OR] for ADHD symptoms of 0.95, 95% confidence interval [CI] = 0.89, 1.01 per 10 µg/m increase in NO2 and 0.98, 95% CI = 0.80, 1.19 per 5 µg/m increase in PM2.5). We observed similar associations for ADHD within the clinical range.

CONCLUSIONS

There was no evidence for an increase in risk of ADHD symptoms with increasing prenatal air pollution levels in children aged 3-10 years. See video abstract at, http://links.lww.com/EDE/B379.

Danger in the Air: Air Pollution and Cognitive Dysfunction

BACKGROUND

Clean air is considered to be a basic requirement for human health and well-being.

OBJECTIVE

To examine the relationship between cognitive performance and ambient pollution exposure.

METHODS

Studies were identified through a systematic search of online scientific databases, in addition to a manual search of the reference lists from the identified papers.

RESULTS

Air pollution is a multifaceted toxic chemical mixture capable of assaulting the central nervous system. Despite being a relatively new area of investigation, overall, there is mounting evidence implicating adverse effects of air pollution on cognitive function in both adults and children.

CONCLUSIONS

Consistent evidence showed that exposure to air pollution, specifically exposure to particulate matter, caused poor age-related cognitive performance. Living in areas with high levels of air pollution has been linked to markers of neuroinflammation and neuropathology that are associated with neurodegenerative conditions such as Alzheimer's disease-like brain pathologies.

Prenatal exposure to environmental pollutants and child development trajectories through 7 years

BACKGROUND

Prenatal exposure to environmental pollutants such as mold, lead, pesticides, tobacco, and air pollutants has been suggested to impair cognitive development. Evidence is needed from longitudinal studies to understand their joint impact on child development across time.

OBJECTIVE

To study associations between exposure to indoor environmental pollutants or outdoor air pollution during pregnancy and offspring cognitive development trajectories through 7 years.

METHODS

We included 718 Mexican mother-child pairs. Prenatal exposure to indoor environmental pollutants (mold, ventilation, pesticides, tobacco smoke, and use of vidiartred clay pots) was self-reported by the mothers and integrated into an index, or objectively measured in the case of outdoor air pollutants (nitrogen oxides, benzene, toluene, and xylene). Child global cognitive development was measured at 12, 18, 60, or 84 months. Using Latent Class Growth Analysis, we identified three developmental trajectories (positive = 108, average = 362, low = 248). We used multinomial logistic models to test associations between environmental pollutant score (EPS) or outdoor air pollutants, and cognitive development trajectories.

RESULTS

After adjustment for sociodemographic covariates, EPS was associated with the average (OR = 1.26 95%CI = 1.01, 1.55) and low (OR = 1.41 95%CI = 1.11, 1.79) trajectories compared to positive; where a unit increase in EPS means an additional prenatal exposure to a pollutant. There was no association between outdoor air pollutants and cognitive development trajectories.

CONCLUSION

Children of women who reported higher exposure to indoor environmental pollutants during pregnancy were more likely to follow worse developmental trajectories through 7 years. These results support the development and testing of interventions to reduce exposure to environmental pollutants during pregnancy and early childhood as a potential strategy to improve long-term cognitive development.

Outdoor and indoor air quality and cognitive ability in young children

BACKGROUND

This study examined outdoor and indoor air quality at ages 9 months and 3 years and their association with cognitive ability at age 3 in England and Wales.

METHOD

Data from 8198 Millennium Cohort Study children were analysed using multilevel regression. Outdoor air quality was assessed with mean annual estimates of nitrogen dioxide (NO₂) levels within a standard small area (ward). Indoor air quality was measured with parent-reports of damp or condensation in the home and exposure to secondhand smoke in the home. Cognitive ability was assessed with the British Ability Scales Naming Vocabulary subscale and the Bracken School Readiness Assessment.

RESULTS

In adjusted models, consistent exposure to high levels of NO₂ at age 9 months and age 3 years was associated with lower verbal ability at age 3 years. Damp/condensation and secondhand smoke in the home at either age or at both ages were correlated with lower school readiness at age 3 years. Exposures to damp/condensation at age 3 years or at both ages and secondhand smoke at either age or at both ages were associated with lower verbal ability at age 3 years.

CONCLUSION

Young children's exposures to indoor damp or condensation and secondhand smoke are likely to be detrimental for their cognitive outcomes. However, there do not appear to be any short-term effects of NO₂.

A critical review of developmental exposure to particulate matter, autism spectrum disorder, and attention deficit hyperactivity disorder

Autism spectrum disorder (ASD) and attention deficit (hyperactivity) disorder (ADD/ADHD) are key focuses of current health research due to their increasing prevalence. The objective of this systematic literature search and critical review was to evaluate whether the human epidemiologic data indicate a pattern of association between ASD or ADD/ADHD and developmental exposure to particulate matter (PM), with a focus on exposures encountered before the age of three. A MEDLINE and EMBASE search was conducted; following preliminary and full-text screening, 14 relevant articles were identified for review. Three of the 14 studies were prospective cohort studies evaluating exposure to PM₁₀; 11 studies had a case-control design. There was no consistent association between developmental PM exposure and ASD across the three of the cohort studies. Seven of the case-control studies examined the relationship between PM_2.5 and/or PM₁₀ and ASD; four examined the relationship between developmental diesel PM exposure and ASD. Overall, there was low external consistency in results among studies of PM_2.5/PM₁₀ and ASD, with some reporting high internal consistency without significant associations, others showing associations with high internal consistency for specific exposure windows only (e.g., third trimester), and still others showing high consistency for moderate to strong associations between PM and ASD. The majority of studies reporting significant results had low effect sizes in conjunction with small sample sizes. The four studies of diesel PM and ASD also had low external consistency of results. Only one study evaluated associations with ADD/ADHD, and it found no significant associations with PM₁₀. The inconsistent findings across studies of developmental exposure to PM and ASD may be attributed to differences in the study populations, exposure assessments, outcome assessments, or chance. Further research is needed to understand the underlying biological mechanisms that lead to ASD and ADD/ADHD and how PM might be involved in those mechanisms, if at all. High-quality epidemiologic studies are also needed to conclusively determine whether developmental PM exposure is a causal factor for ASD or ADD/ADHD, with focus on a well-developed exposure assessment.

Association between neighbourhood air pollution concentrations and dispensed medication for psychiatric disorders in a large longitudinal cohort of Swedish children and adolescents

OBJECTIVE

To investigate associations between exposure to air pollution and child and adolescent mental health.

DESIGN

Observational study.

SETTING

Swedish National Register data on dispensed medications for a broad range of psychiatric disorders, including sedative medications, sleeping pills and antipsychotic medications, together with socioeconomic and demographic data and a national land use regression model for air pollution concentrations for NO2, PM10 and PM2.5.

PARTICIPANTS

The entire population under 18 years of age in 4 major counties. We excluded cohort members whose parents had dispensed a medication in the same medication group since the start date of the register. The cohort size was 552 221.

MAIN OUTCOME MEASURES

Cox proportional hazards models to estimate HRs and their 95% CIs for the outcomes, adjusted for individual-level and group-level characteristics.

RESULTS

The average length of follow-up was 3.5 years, with an average number of events per 1000 cohort members of ∼21. The mean annual level of NO2 was 9.8 µg/m(3). Children and adolescents living in areas with higher air pollution concentrations were more likely to have a dispensed medication for a psychiatric disorder during follow-up (HR=1.09, 95% CI 1.06 to 1.12, associated with a 10 µg/m(3) increase in NO2). The association with NO2 was clearly present in 3 out of 4 counties in the study area; however, no statistically significant heterogeneity was detected.

CONCLUSION

There may be a link between exposure to air pollution and dispensed medications for certain psychiatric disorders in children and adolescents even at the relatively low levels of air pollution in the study regions. The findings should be corroborated by others.

Results of the California Healthy Homes Indoor Air Quality Study of 2011-2013: impact of natural gas appliances on air pollutant concentrations

This study was conducted to assess the current impact of natural gas appliances on air quality in California homes. Data were collected via telephone interviews and measurements inside and outside of 352 homes. Passive samplers measured time-resolved CO and time-integrated NOX , NO2 , formaldehyde, and acetaldehyde over ~6-day periods in November 2011 - April 2012 and October 2012 - March 2013. The fraction of indoor NOX and NO2 attributable to indoor sources was estimated. NOX , NO2 , and highest 1-h CO were higher in homes that cooked with gas and increased with amount of gas cooking. NOX and NO2 were higher in homes with cooktop pilot burners, relative to gas cooking without pilots. Homes with a pilot burner on a floor or wall furnace had higher kitchen and bedroom NOX and NO2 compared to homes without a furnace pilot. When scaled to account for varying home size and mixing volume, indoor-attributed bedroom and kitchen NOX and kitchen NO2 were not higher in homes with wall or floor furnace pilot burners, although bedroom NO2 was higher. In homes that cooked 4 h or more with gas, self-reported use of kitchen exhaust was associated with lower NOX , NO2 , and highest 1-h CO. Gas appliances were not associated with higher concentrations of formaldehyde or acetaldehyde.

NO2 inhalation promotes Alzheimer's disease-like progression: cyclooxygenase-2-derived prostaglandin E2 modulation and monoacylglycerol lipase inhibition-targeted medication

Air pollution has been reported to be associated with increased risks of cognitive impairment and neurodegenerative diseases. Because NO2 is a typical primary air pollutant and an important contributor to secondary aerosols, NO2-induced neuronal functional abnormalities have attracted greater attention, but the available experimental evidence, modulating mechanisms, and targeting medications remain ambiguous. In this study, we exposed C57BL/6J and APP/PS1 mice to dynamic NO2 inhalation and found for the first time that NO2 inhalation caused deterioration of spatial learning and memory, aggravated amyloid β42 (Aβ42) accumulation, and promoted pathological abnormalities and cognitive defects related to Alzheimer's disease (AD). The microarray and bioinformation data showed that the cyclooxygenase-2 (COX-2)-mediated arachidonic acid (AA) metabolism of prostaglandin E2 (PGE2) played a key role in modulating this aggravation. Furthermore, increasing endocannabinoid 2-arachidonoylglycerol (2-AG) by inhibiting monoacylglycerol lipase (MAGL) prevented PGE2 production, neuroinflammation-associated Aβ42 accumulation, and neurodegeneration, indicating a therapeutic target for relieving cognitive impairment caused by NO2 exposure.

Rethinking Meta-Analysis: Applications for Air Pollution Data and Beyond

Meta-analyses offer a rigorous and transparent systematic framework for synthesizing data that can be used for a wide range of research areas, study designs, and data types. Both the outcome of meta-analyses and the meta-analysis process itself can yield useful insights for answering scientific questions and making policy decisions. Development of the National Ambient Air Quality Standards illustrates many potential applications of meta-analysis. These applications demonstrate the strengths and limitations of meta-analysis, issues that arise in various data realms, how meta-analysis design choices can influence interpretation of results, and how meta-analysis can be used to address bias and heterogeneity. Reviewing available data from a meta-analysis perspective can provide a useful framework and impetus for identifying and refining strategies for future research. Moreover, increased pervasiveness of a meta-analysis mindset-focusing on how the pieces of the research puzzle fit together-would benefit scientific research and data syntheses regardless of whether or not a quantitative meta-analysis is undertaken. While an individual meta-analysis can only synthesize studies addressing the same research question, the results of separate meta-analyses can be combined to address a question encompassing multiple data types. This observation applies to any scientific or policy area where information from a variety of disciplines must be considered to address a broader research question.

Acute nitrogen dioxide inhalation induces mitochondrial dysfunction in rat brain

Recent epidemiological literatures imply that NO2 is a potential risk factor of neurological disorders. Whereas, the pathogenesis of various neurological diseases has been confirmed correlate to mitochondrial dysfunction, and mitochondria play the crucial roles in energy metabolism, free radicals production and apoptosis triggering in response to neuronal injury. Therefore, to clarify the possible mechanisms for NO2-induced neurotoxicity, in the present study, we investigated the possible effects of acute NO2 inhalation (5, 10 and 20mg/m(3) with 5h/day for 7 days) on energy metabolism and biogenesis in rat cortex, mainly including mitochondrial ultrastructure, mitochondrial membrane potential, cytochrome c oxidase activity, cytochrome c oxidase (CO) and ATP synthase subunits, ATP content, and transcription factors. The results showed that NO2 exposure induced mitochondrial morphological changes in rat cortex, and the alteration was coupled with the abnormality of mitochondrial energy metabolism, including decreased respiratory complexes, reduced ATP production and increased production of ROS. Also, increased ROS in turn caused mitochondrial membrane damage, energy production defect and mitochondrial biogenesis inhibition. It suggests the significantly damaged mitochondrial energy metabolism and impaired biogenesis in rat brain after NO2 exposure, and provides a new understanding of the pathophysiological mechanisms of NO2-induced neurological disorders.

Exposure to Air Pollution From Traffic and Neurodevelopmental Disorders in Swedish Twins

Background: Recent studies have reported associations between air pollution exposure and neurodevelopmental disorders in children, but the role of pre- and postnatal exposure has not been elucidated. Aim: We aimed to explore the risk for autism spectrum disorders (ASD) and attention-deficit hyperactivity disorder (ADHD) among children in relation to pre- and postnatal exposure to air pollution from road traffic. Methods: Parents of 3,426 twins born in Stockholm during 1992–2000 were interviewed, when their children were 9 or 12 years old, for symptoms of neurodevelopmental disorders. Residence time-weighted concentrations of particulate matter with a diameter <10 μm (PM10) and nitrogen oxides (NOx) from road traffic were estimated at participants’ addresses during pregnancy, the first year, and the ninth year of life using dispersion modeling, controlling for seasonal variation. Multivariate regression models were used to examine the association between air pollution exposure and neurodevelopmental outcomes, adjusting for potential confounding factors. Results: No clear or consistent associations were found between air pollution exposure during any of the three time windows and any of the neurodevelopmental outcomes. For example, a 5–95% difference in exposure to NOx during pregnancy was associated with odds ratios (ORs) of 0.92 (95% confidence interval (CI): 0.44–1.96) and 0.90 (95% CI: 0.58–1.40) for ASD and ADHD respectively. A corresponding range in exposure to PM10 during pregnancy was related to ORs of 1.01 (95% CI: 0.52–1.96) and 1.00 (95% CI: 0.68–1.47) for ASD and ADHD. Conclusions: Our data do not provide support for an association between pre- or postnatal exposure to air pollution from road traffic and neurodevelopmental disorders in children.

Increased risk of dementia in patients exposed to nitrogen dioxide and carbon monoxide: a population-based retrospective cohort study

Background

The air pollution caused by vehicular emissions is associated with cognitive decline. However, the associations between the levels of nitrogen dioxide (NO₂) and carbon monoxide (CO) exposure and dementia remain poorly defined and have been addressed in only a few previous studies.

Materials and Methods

In this study, we obtained data on 29547 people from the National Health Insurance Research Database (NHIRD) of Taiwan, including data on 1720 patients diagnosed with dementia between 2000 and 2010, and we evaluated the risk of dementia among four levels of air pollutant. Detailed data on daily air pollution were available from January 1, 1998 to December 31, 2010. Yearly average concentrations of pollutants were calculated from the baseline to the date of dementia occurrence, withdrawal of patients, or the end of the study, and these data were categorized into quartiles, with Q1 being the lowest level and Q4 being the highest.

Results

In the case of NO₂, the adjusted hazard ratios (HRs) of dementia for all participants in Q2, Q3, and Q4 compared to Q1 were 1.10 (95% confidence interval (CI), 0.96–1.26), 1.01 (95% CI, 0.87–1.17), and 1.54 (95% CI, 1.34–1.77), and in the case of CO, the adjusted HRs were 1.07 (95% CI, 0.92–1.25), 1.37 (95% CI, 1.19–1.58), and 1.61 (95% CI, 1.39–1.85).

Conclusion

The results of this large retrospective, population-based study indicate that exposure to NO₂ and CO is associated with an increased risk of dementia in the Taiwanese population.

Prenatal exposure to PM₁₀ and NO₂ and children's neurodevelopment from birth to 24 months of age: mothers and Children's Environmental Health (MOCEH) study

INTRODUCTION

Previous studies have suggested adverse effects of maternal exposure to air pollution on neurodevelopment in early childhood.

OBJECTIVES

We aimed to investigate the association between prenatal exposure to particulates of less than 10 μm in diameter (PM10) and nitrogen dioxide (NO2) and neurodevelopment in children during the first 24 months of their lives.

METHODS

The MOCEH study is a prospective birth cohort study in South Korea. Average exposure levels to PM10 and NO2 during the entire pregnancy were estimated using the inverse distance weighting (IDW) method. A total of 520 mother-child pairs who completed neurodevelopmental assessments using the Korean Bayley Scale of Infant Development II (K-BSID-II) more than once at ages of 6, 12 and 24 months were included. Mental developmental index (MDI) and psychomotor developmental index (PDI) from the K-BSID-II were used as outcome variables.

RESULTS

There were negative associations between maternal exposure to PM10 and MDI (β=-2.83; p=0.003) and PDI (β=-3.00; p=0.002) throughout the first 24 months of life as determined by the generalized estimating equation (GEE) model. Maternal NO2 exposure was related with impairment of psychomotor development (β=-1.30; p=0.05) but not with cognitive function (β=-0.84; p=0.20). In a multiple linear regression model, there were significant effects of prenatal air pollution exposure on MDI (PM10: β=-4.60; p<0.001, NO2: β=-3.12; p<0.001) and PDI (PM10: β=-7.24; p<0.001, NO2: β=-3.01; p<0.001) at 6 months, but no significant association was found at 12 and 24 months of age.

CONCLUSIONS

The findings suggest that exposure to air pollution may result in delayed neurodevelopment in early childhood.

Exposure to air pollution and respiratory symptoms during the first 7 years of life in an Italian birth cohort

Background

Ambient air pollution has been consistently associated with exacerbation of respiratory diseases in schoolchildren, but the role of early exposure to traffic-related air pollution in the first occurrence of respiratory symptoms and asthma is not yet clear.

Methods

We assessed the association between indexes of exposure to traffic-related air pollution during different periods of life and respiratory outcomes in a birth cohort of 672 newborns (Rome, Italy). Direct interviews of the mother were conducted at birth and at 6, 15 months, 4 and 7 years. Exposure to traffic-related air pollution was assessed for each residential address during the follow-up period using a Land-Use Regression model (LUR) for nitrogen dioxide (NO₂) and a Geographic Information System (GIS) variable of proximity to high-traffic roads (HTR) (>10 000vehicles/day). We used age-specific NO₂ levels to develop indices of exposure at birth, current, and lifetime time-weighted average. The association of NO₂ and traffic proximity with respiratory disorders were evaluated using logistic regression in a longitudinal approach (Generalised Estimating Equation). The exposure indexes were used as continuous and categorical variables (cut-off points based on the 75th percentile for NO₂ and the 25th percentile for distance from HTRs).

Results

The average NO₂ exposure level at birth was 37.2 μg/m³ (SD 7.2, 10–90th range 29.2–46.1). There were no statistical significant associations between the exposure indices and the respiratory outcomes in the longitudinal model. The odds ratios for a 10-µg/m³ increase in time-weighted average NO₂ exposure were: asthma incidence OR=1.09; 95 CI% 0.78 to 1.52, wheezing OR=1.07; 95 CI% 0.90 to 1.28, shortness of breath with wheezing OR=1.16; 95 CI% 0.94 to 1.43, cough or phlegm apart from cold OR=1.11; 95 CI% 0.92 to 1.33, and otitis OR=1.08; 95 CI% 0.89 to 1.32. Stronger but not significant associations were found considering the 75th percentile of the NO₂ distribution as a cut-off, especially for incidence of asthma and prevalence of wheeze (OR=1.41; 95 CI% 0.88 to 2.28 and OR=1.27; 95 CI% 0.95 to 1.70, respectively); the highest OR was found for wheezing (OR=2.29; 95 CI% 1.15 to 4.56) at the 7-year follow-up. No association was found with distance from HTRs.

Conclusions

Exposure to traffic-related air pollution is only weakly associated with respiratory symptoms in young children in the first 7 years of life.

Traffic-related air pollution exposure in the first year of life and behavioral scores at 7 years of age

BACKGROUND

There is increasing concern about the potential effects of traffic-related air pollution (TRAP) on the developing brain. The impact of TRAP exposure on childhood behavior is not fully understood because of limited epidemiologic studies.

OBJECTIVE

We explored the association between early-life exposure to TRAP using a surrogate, elemental carbon attributed to traffic (ECAT), and attention deficit/hyperactivity disorder (ADHD) symptoms at 7 years of age.

METHODS

From the Cincinnati Childhood Allergy and Air Pollution Study (CCAAPS) birth cohort we collected data on exposure to ECAT during infancy and behavioral scores at 7 years of age. Children enrolled in CCAAPS had at least one atopic parent and a birth residence either < 400 m or > 1,500 m from a major highway. Children were followed from infancy through 7 years of age. ECAT exposure during the first year of life was estimated based on measurements from 27 air sampling sites and land use regression modeling. Parents completed the Behavioral Assessment System for Children, 2nd Edition, when the child was 7 years of age. ADHD-related symptoms were assessed using the Hyperactivity, Attention Problems, Aggression, Conduct Problems, and Atypicality subscales.

RESULTS

Exposure to the highest tertile of ECAT during the child's first year of life was significantly associated with Hyperactivity T-scores in the "at risk" range at 7 years of age, after adjustment [adjusted odds ratio (aOR) = 1.7; 95% CI: 1.0, 2.7]. Stratification by maternal education revealed a stronger association in children whose mothers had higher education (aOR = 2.3; 95% CI: 1.3, 4.1).

CONCLUSIONS

ECAT exposure during infancy was associated with higher Hyperactivity scores in children; this association was limited to children whose mothers had more than a high school education.

Exposure to widespread environmental toxicants and children's cognitive development and behavioral problems

Nowadays a special attention is focused on prenatal and childhood exposures to a variety of contaminants in the environment, especially toxicants widely present in the environment and their impact on children's health and neurodevelopment. This article aims at evaluating the impact of exposure to several widespread toxicants including: polycyclic aromatic hydrocarbons (PAHs), phthalates, bisphenol A, brominated flame retardants and gas cooking on children's cognitive development and behavioral problems by reviewing most recent published literature. Epidemiological studies focusing on exposure to widespread toxicants and children's development for the last eleven years were identified by a search of the PubMed, Medline, Ebsco and Toxnet literature bases. The combination of following key words was used: 1) referring to the exposure: pregnancy, prenatal exposure, postnatal exposure, gas cooking, exposure to phthalates, bisphenol A, brominated flame retardants, PAHs and 2) referring to outcome: neurodevelopment, neurobehavior, psychomotor development, behavioral problems, cognitive development, mental health, school achievements, learning abilities. The results from the presented studies suggest that there are strong and rather consistent indications that the developing nervous system is particularly vulnerable to insult from low levels of exposure to widespread environmental contaminants such as: phthalates, bisphenol A, brominated flame retardants, polycyclic aromatic hydrocarbons, gas cooking. Considering the suggested health effects, more epidemiologic data is urgently needed and, in the meantime, precautionary policies must be implemented.

The role of MAC1 in diesel exhaust particle-induced microglial activation and loss of dopaminergic neuron function

Increasing reports support that air pollution causes neuroinflammation and is linked to central nervous system (CNS) disease/damage. Diesel exhaust particles (DEP) are a major component of urban air pollution, which has been linked to microglial activation and Parkinson's disease-like pathology. To begin to address how DEP may exert CNS effects, microglia and neuron-glia cultures were treated with either nanometer-sized DEP (< 0.22 μM; 50 μg/mL), ultrafine carbon black (ufCB, 50 μg/mL), or DEP extracts (eDEP; from 50 μg/mL DEP), and the effect of microglial activation and dopaminergic (DA) neuron function was assessed. All three treatments showed enhanced ameboid microglia morphology, increased H2 O2 production, and decreased DA uptake. Mechanistic inquiry revealed that the scavenger receptor inhibitor fucoidan blocked DEP internalization in microglia, but failed to alter DEP-induced H2 O2 production in microglia. However, pre-treatment with the MAC1/CD11b inhibitor antibody blocked microglial H2 O2 production in response to DEP. MAC1(-/-) mesencephalic neuron-glia cultures were protected from DEP-induced loss of DA neuron function, as measured by DA uptake. These findings support that DEP may activate microglia through multiple mechanisms, where scavenger receptors regulate internalization of DEP and the MAC1 receptor is mandatory for both DEP-induced microglial H2 O2 production and loss of DA neuron function.

Analysis of an environmental exposure health questionnaire in a metropolitan minority population utilizing logistic regression and Support Vector Machines

The goal of this study was to analyze a 54-item instrument for assessment of perception of exposure to environmental contaminants within the context of the built environment, or exposome. This exposome was defined in five domains to include 1) home and hobby, 2) school, 3) community, 4) occupation, and 5) exposure history. Interviews were conducted with child-bearing-age minority women at Metro Nashville General Hospital at Meharry Medical College. Data were analyzed utilizing DTReg software for Support Vector Machine (SVM) modeling followed by an SPSS package for a logistic regression model. The target (outcome) variable of interest was respondent's residence by ZIP code. The results demonstrate that the rank order of important variables with respect to SVM modeling versus traditional logistic regression models is almost identical. This is the first study documenting that SVM analysis has discriminate power for determination of higher-ordered spatial relationships on an environmental exposure history questionnaire.

The outdoor air pollution and brain health workshop

Accumulating evidence suggests that outdoor air pollution may have a significant impact on central nervous system (CNS) health and disease. To address this issue, the National Institute of Environmental Health Sciences/National Institute of Health convened a panel of research scientists that was assigned the task of identifying research gaps and priority goals essential for advancing this growing field and addressing an emerging human health concern. Here, we review recent findings that have established the effects of inhaled air pollutants in the brain, explore the potential mechanisms driving these phenomena, and discuss the recommended research priorities/approaches that were identified by the panel.

Dietary benzo(a)pyrene and fetal growth: effect modification by vitamin C intake and glutathione S-transferase P1 polymorphism

BACKGROUND

Previous studies have reported maternal exposure to airborne polycyclic aromatic hydrocarbons (PAH), as well as DNA adducts reflecting total PAH exposure, to be associated with reduced fetal growth. The role of diet, the main source of PAH exposure among non-smokers, remains uncertain.

OBJECTIVE

To assess associations between birth weight, length and small size for gestational age (SGA) with maternal intakes of the genotoxic PAH benzo(a)pyrene [B(a)P] during pregnancy, exploring potential effect modification by dietary intakes of vitamin C, vitamin E, alpha- and beta-carotene, as well as glutathione S-transferase P1 (GSTP1) polymorphisms, hypothesized to influence PAH metabolism.

METHODS

657 women in the INMA (Environment and Childhood) Project from Sabadell (Barcelona) were recruited during the first trimester of pregnancy. Dietary B(a)P and nutrient intakes were estimated from food consumption data. Genotyping was conducted for the Ile105Val variant of GSTP1. Multivariable models were used to assess associations between size at birth and dietary B(a)P, evaluating potential interactions with candidate nutrients and GSTP1 variants.

RESULTS

There were significant interactions between elevated intakes of vitamin C (above the mean of 189.41 mg/day) and dietary B(a)P during the first trimester of pregnancy in models for birth weight and length (P<0.05), but no interactions were found with other nutrients. B(a)P intakes were associated with significant reductions in birth weight and length (coefficient±SE for a 1-SD increase in B(a)P: -101.63±34.62 g and -0.38±0.16 cm, respectively) among women with low, but not high, vitamin C intakes. Elevated dietary B(a)P was also associated with increased risk of SGA births among women with low dietary vitamin C. Among these women, associations were strongest in those carrying the GSTP1 Val allele, associated with lower contaminant detoxification activity.

CONCLUSION

Results suggest that dietary B(a)P exposure may impair fetal growth, particularly in genetically susceptible populations, and that increasing maternal intakes of vitamin C may help to reduce any adverse effects.

Longitudinal association between early life socio-environmental factors and attention function at the age 11 years

Prenatal and early-life exposures can affect the course of children's neuropsychological development well into pre-adolescence, given the vulnerability of the developing brain. However, it is unknown which socio-environmental factors at early childhood can influence specific cognitive processes like attention at a later age. In this study, we aim to determine social and environmental exposures in early childhood that may be associated with attention function of 11-year-olds. We measured attention function using the continuous performance test-II (CPT-II) on 393 11-year old children from the Menorca's birth-cohort within the INMA-project (Spain), and pre-selected a list of socio-environmental observations taken when they were up to 4 years of age. We found that earlier socio-environmental characteristics, such as parental social class, educational level and maternal mental health are associated with later inattentive and impulsive symptomatology through a higher rate of omission and commission errors. In addition, omission errors were higher in children with atopy and lower in those whose mothers took dietary supplementation with folic acid and vitamins during pregnancy. Breastfeeding played a protective role against commission errors, while higher DDE and PCBs levels at age 4 were associated with slow speed response. Our findings suggest that a number of life socio-environmental factors during prenatal life and early childhood, such as socio-demographic characteristics, breastfeeding, maternal nutritional supplementation with folic acid and vitamins and exposure to some organochlorine compounds may influence inattentive and hyperactive/impulsive symptomatology during pre-adolescence.

Specific language disorders and season of birth: underlying environmental factors or chance findings?

The medical records of 358 children and adolescents with specific language disorders (SLD; 122 girls and 236 boys) seen in rehabilitation centers from Northern and Central Italy were examined to compare season of birth in these cases to those of the Italian population. Exposure was calculated using univariate and multivariate odds ratios (ORs) and 95% confidence intervals (CIs). Compared to the Italian population, patients with SLD had a 1.67 (95% CI [1.35-2.07]) chance of birth in October-December. Independent predictors were younger age at inclusion and being firstborn. Different neurobiological hypotheses can be drawn to explain these findings.