Associations between mitochondrial biomarkers, urban residential exposures and childhood asthma outcomes over 6 months

Determining biomarkers of responses to environmental exposures and evaluating whether they predict respiratory outcomes may help optimize environmental and medical approaches to childhood asthma. Relative mitochondrial (mt) DNA abundance and other potential mitochondrial indicators of oxidative stress may provide a sensitive metric of the child's shifting molecular responses to its changing environment. We leveraged two urban childhood cohorts (Environmental Control as Add-on Therapy in Childhood Asthma (ECATCh); Columbia Center for Children's Environmental Health (CCCEH)) to ascertain whether biomarkers in buccal mtDNA associate with airway inflammation and altered lung function over 6 months of time and capture biologic responses to multiple external stressors such as indoor allergens and fine particulate matter (PM2.5). Relative mtDNA content was amplified by qPCR and methylation of transfer RNA phenylalanine/rRNA 12S (TF/RNR1), cytochrome c oxidase (CO1), and carboxypeptidase O (CPO) was measured by pyrosequencing. Data on residential exposures and respiratory outcomes were harmonized between the two cohorts. Repeated measures and multiple regression models were utilized to assess relationships between mitochondrial biomarkers, respiratory outcomes, and residential exposures (PM2.5, allergens), adjusted for potential confounders and time-varying asthma. We found across the 6 month visits, a 0.64 fold higher level of TF/RNR1 methylation was detected among those with asthma in comparison to those without asthma ((parameter estimate (PE) 0.64, standard error 0.28, p = 0.03). In prospective analyses, CPO methylation was associated with subsequent reduced forced vital capacity (FVC; PE -0.03, standard error 0.01, p = 0.02). Bedroom dust mouse allergen, but not indoor PM2.5, was associated with higher methylation of TF/RNR1 (PE 0.015, standard error 0.006, p = 0.01). Select mtDNA measures in buccal cells may indicate children's responses to toxic environmental exposures and associate selectively with asthma and lung function.

When a birth cohort grows up: challenges and opportunities in longitudinal developmental origins of health and disease (DOHaD) research

High-quality evidence from prospective longitudinal studies in humans is essential to testing hypotheses related to the developmental origins of health and disease. In this paper, the authors draw upon their own experiences leading birth cohorts with longitudinal follow-up into adulthood to describe specific challenges and lessons learned. Challenges are substantial and grow over time. Long-term funding is essential for study operations and critical to retaining study staff, who develop relationships with participants and hold important institutional knowledge and technical skill sets. To maintain contact, we recommend that cohorts apply multiple strategies for tracking and obtain as much high-quality contact information as possible before the child's 18th birthday. To maximize engagement, we suggest that cohorts offer flexibility in visit timing, length, location, frequency, and type. Data collection may entail multiple modalities, even at a single collection timepoint, including measures that are self-reported, research-measured, and administrative with a mix of remote and in-person collection. Many topics highly relevant for adolescent and young adult health and well-being are considered to be private in nature, and their assessment requires sensitivity. To motivate ongoing participation, cohorts must work to understand participant barriers and motivators, share scientific findings, and provide appropriate compensation for participation. It is essential for cohorts to strive for broad representation including individuals from higher risk populations, not only among the participants but also the staff. Successful longitudinal follow-up of a study population ultimately requires flexibility, adaptability, appropriate incentives, and opportunities for feedback from participants.

Prenatal exposure to polybrominated diphenyl ethers and birth outcomes

BACKGROUND

Polybrominated diphenyl ethers (PBDEs) were used as flame retardants and from their end-use products they can be released to accumulate within indoor environments. This may result in exposures to pregnant women with potential adverse effects on the developing fetus. While studies have shown associations between prenatal PBDE exposure and poor birth outcomes, research has mainly focused on birth weight and gestational age and may miss important indicators of newborn size.

METHODS

The sample included a cohort of Dominican and African American mother-child pairs from New York City recruited from 1998 to 2006. PBDE congeners (BDE-47, BDE-99, BDE-100, and BDE-153) were measured in cord serum at birth and dichotomized into low (<80th percentile) and high (>80th percentile) categories. Weight, length, head circumference, and gestational age were measured at birth and the ponderal index (birth weight/length x 100), size for gestational age, and population-based z-scores were calculated (n = 305). Separate regression analyses were conducted to estimate associations between PBDEs or PBDE sum (ng/g lipid) and birth outcomes. Quantile g-computation was performed to estimate the effect of total PBDE mixture. We also assessed effect modification by sex and ethnicity.

RESULTS

Adjusting for relevant covariates, the high exposure category of BDE-153 was associated with lower birth weight z-score (-0.25, 95% CI: -0.5, 0.0) and longer gestation (0.43 weeks, 95% CI: 0.07, 0.79). The high exposure category of BDE-99 was associated with lower birth length z-score (-0.55, 95% CI: -0.98, -0.12). There was a negative association between the overall PBDE mixture and birth length z-score (-0.10, 95% CI: -0.21, 0.00) per 1 quintile increase in PBDEs. There was no effect modification by sex or ethnicity.

CONCLUSIONS

These results suggest that prenatal exposures to BDE-153, BDE-99, and total PBDE mixture are associated with birth outcomes in a cohort of Dominican and African American newborns.

Assessment of the health benefits to children of a transportation climate policy in New York City

BACKGROUND

Assessments of health and environmental effects of clean air and climate policies have revealed substantial health benefits due to reductions in air pollution, but have included few pediatric outcomes or assessed benefits at the neighborhood level.

OBJECTIVES

We estimated benefits across a suite of child health outcomes in 42 New York City (NYC) neighborhoods under the proposed regional Transportation and Climate Initiative. We also estimated their distribution across racial/ethnic and socioeconomic groups.

METHODS

We estimated changes in ambient fine particulate matter (PM_2.5) and nitrogen dioxide (NO₂) concentrations associated with on-road emissions under nine different predefined cap-and-invest scenarios. Health outcomes, including selected adverse birth, respiratory, and neurodevelopmental outcomes, were estimated using a program similar to the U.S. EPA BenMAP program. We stratified the associated monetized benefits across racial/ethnic and socioeconomic groups.

RESULTS

The benefits varied widely over the different cap-and-investment scenarios. For a 25% reduction in carbon emissions from 2022 to 2032 and a strategy prioritizing public transit investments, NYC would have an estimated 48 fewer medical visits for childhood asthma, 13,000 avoided asthma exacerbations not requiring medical visits, 640 fewer respiratory illnesses unrelated to asthma, and 9 avoided adverse birth outcomes (infant mortality, preterm birth, and term low birth weight) annually, starting in 2032. The total estimated annual avoided costs are $22 million. City-wide, Black and Hispanic children would experience 1.7 times the health benefits per capita than White and Non-Hispanic White children, respectively. Under the same scenario, neighborhoods experiencing the highest poverty rates in NYC would experience about 2.5 times the health benefits per capita than the lowest poverty neighborhoods.

CONCLUSION

A cap-and-invest strategy to reduce carbon emissions from the transportation sector could provide substantial health and monetized benefits to children in NYC through reductions in criteria pollutant concentrations, with greater benefits among Black and Hispanic children.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Cancer Risk Reduction Through Education of Adolescents: Development of a Tailored Cancer Risk-Reduction Educational Tool

Growing evidence links adolescent exposures to cancer risk later in life, particularly for common cancers like breast. The adolescent time period is also important for cancer risk reduction as many individual lifestyle behaviors are initiated including smoking and alcohol use. We developed a cancer risk-reduction educational tool tailored for adolescents that focused on five modifiable cancer risk factors. To contextualize risk factors in adolescents' social and physical environments, the intervention also focused on structural barriers to individual- and community-level change, with an emphasis on environmental justice or the fair treatment and meaningful involvement of all people regardless of race, color, national origin, or income with respect to the development, implementation, and enforcement of environmental laws, regulations, and policies. The educational tool consisted of a 50-min module that included an introduction to cancer biology including genetic susceptibility and environmental interactions, cancer burden in the local community, and risk reduction strategies. The module also included an interactive activity in which adolescent students identify cancer risk factors and brainstorm strategies for risk reduction at both the individual and community level. We administered the module to 12 classes of over 280 high school and college students in New York City. Cancer risk reduction strategies identified by the students included family- or peer-level strategies such as team physical activity and community-level action including improving parks and taxing sugary foods. We developed a novel and interactive cancer risk-reduction education tool focused on multiple cancers that can be adopted by other communities and educational institutions.

Association Studies of Environmental Exposures, DNA Methylation and Children’s Cognitive, Behavioral, and Mental Health Problems

Introduction: Prenatal environmental exposures have been associated with children’s cognitive, behavioral, and mental health problems, and alterations in DNA methylation have been hypothesized as an underlying biological mechanism. However, when testing this hypothesis, it is often difficult to overcome the problem of multiple comparisons in statistical testing when evaluating a large number of developmental outcomes and DNA methylation sites as potential mediators. The objective of this study is to implement a ‘meet-in-the-middle’ approach with a sequential roadmap to address this concern.

Methods: In the Columbia Center for Children’s Environmental Health birth cohort study, we implemented a 5-step sequential process for identifying CpG sites that mediate associations between prenatal environmental exposures and cognitive, behavioral, and mental health problems as measured by the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) and the Child Behavior Checklist (CBCL). These steps include 1) the identification of biological pathways that are relevant to each outcome of interest; 2) selection of a set of genes and CpGs on genes that are significantly associated with the outcomes; 3) identification of exposures that are significantly associated with selected CpGs; 4) examination of exposure-outcome relationships among those where significant CpGs were identified; and 5) mediation analysis of the selected exposures and corresponding outcomes. In this study, we considered a spectrum of environmental exposure classes including environmental phenols, pesticides, phthalates, flame retardants and air pollutants.

Results: Among all considered exposures and outcomes, we found one CpG site (cg27510182) on gene (DAB1) that potentially mediates the effect of exposure to PAH on CBCL social problems at children aged 7.

Conclusion: This ‘meet-in-the-middle’ approach attenuates concerns regarding multiple comparisons by focusing on genes and pathways that are biologically relevant for the hypothesis.

Prenatal PM2.5 Exposure in Relation to Maternal and Newborn Telomere Length at Delivery

Particulate matter with an aerodynamic diameter of 2.5 μm or less (PM_2.5) is a ubiquitous air pollutant that is increasingly threatening the health of adults and children worldwide. One health impact of elevated PM_2.5 exposure is alterations in telomere length (TL)-protective caps on chromosome ends that shorten with each cell division. Few analyses involve prenatal PM_2.5 exposure, and paired maternal and cord TL measurements. Here, we analyzed the association between average and trimester-specific prenatal PM_2.5 exposure, and maternal and newborn relative leukocyte TL measured at birth among 193 mothers and their newborns enrolled in a New-York-City-based birth cohort. Results indicated an overall negative relationship between prenatal PM_2.5 and maternal TL at delivery, with a significant association observed in the second trimester (β = -0.039, 95% CI: -0.074, -0.003). PM_2.5 exposure in trimester two was also inversely related to cord TL; however, this result did not reach statistical significance (β = -0.037, 95% CI: -0.114, 0.039), and no clear pattern emerged between PM_2.5 and cord TL across the different exposure periods. Our analysis contributes to a limited body of research on ambient air pollution and human telomeres, and emphasizes the need for continued investigation into how PM_2.5 exposure during pregnancy influences maternal and newborn health.

Exposure to polycyclic aromatic hydrocarbons during pregnancy and breast tissue composition in adolescent daughters and their mothers: a prospective cohort study

BACKGROUND

Polycyclic aromatic hydrocarbons (PAH), which are found in air pollution, have carcinogenic and endocrine disrupting properties that might increase breast cancer risk. PAH exposure might be particularly detrimental during pregnancy, as this is a time when the breast tissue of both the mother and daughter is undergoing structural and functional changes. In this study, we tested the hypothesis that ambient PAH exposure during pregnancy is associated with breast tissue composition, measured one to two decades later, in adolescent daughters and their mothers.

METHODS

We conducted a prospective analysis using data from a New York City cohort of non-Hispanic Black and Hispanic mother-daughter dyads (recruited 1998-2006). During the third trimester of pregnancy, women wore backpacks containing a continuously operating air sampling pump for two consecutive days that measured ambient exposure to eight carcinogenic higher molecular weight nonvolatile PAH compounds (Σ8 PAH) and pyrene. When daughters (n = 186) and mothers (n = 175) reached ages 11-20 and 29-55 years, respectively, optical spectroscopy (OS) was used to evaluate measures of breast tissue composition (BTC) that positively (water content, collagen content, optical index) and negatively (lipid content) correlate with mammographic breast density, a recognized risk factor for breast cancer. Multivariable linear regression was used to evaluate associations between ambient PAH exposure and BTC, overall and by exposure to household tobacco smoke during pregnancy (yes/no). Models were adjusted for race/ethnicity, age, and percent body fat at OS.

RESULTS

No overall associations were found between ambient PAH exposure (Σ8 PAH or pyrene) and BTC, but statistically significant additive interactions between Σ8 PAH and household tobacco smoke exposure were identified for water content and optical index in both daughters and mothers (interaction p values < 0.05). Σ8 PAH exposure was associated with higher water content (β_daughters = 0.42, 95% CI = 0.15-0.68; β_mothers = 0.32, 95% CI = 0.05-0.61) and higher optical index (β_daughters = 0.38, 95% CI = 0.12-0.64; β_mothers = 0.38, 95% CI = 0.12-0.65) in those exposed to household tobacco smoke during pregnancy; no associations were found in non-smoking households (interaction p values < 0.05).

CONCLUSIONS

Exposure to ambient Σ8 PAH and tobacco smoke during pregnancy might interact synergistically to impact BTC in mothers and daughters. If replicated in other cohorts, these findings might have important implications for breast cancer risk across generations.

The Role of Childhood Asthma in Obesity Development: A Nationwide US Multicohort Study

RATIONALE

Asthma and obesity often co-occur. It has been hypothesized that asthma may contribute to childhood obesity onset.

OBJECTIVES

To determine if childhood asthma is associated with incident obesity and examine the role of asthma medication in this association.

METHODS

We studied 8,716 children between ages 6 and 18.5 years who were nonobese at study entry participating in 18 US cohorts of the Environmental influences on Child Health Outcomes program (among 7,299 children with complete covariate data mean [SD] study entry age = 7.2 [1.6] years and follow up = 5.3 [3.1] years).

MEASUREMENTS AND MAIN RESULTS

We defined asthma based on caregiver report of provider diagnosis. Incident obesity was defined as the first documented body mass index ≥95th percentile for age and sex following asthma status ascertainment. Over the study period, 26% of children had an asthma diagnosis and 11% developed obesity. Cox proportional hazards models with sex-specific baseline hazards were fitted to assess the association of asthma diagnosis with obesity incidence. Children with asthma had a 23% (95% confidence intervals [CI] = 4, 44) higher risk for subsequently developing obesity compared with those without asthma. A novel mediation analysis was also conducted to decompose the total asthma effect on obesity into pathways mediated and not mediated by asthma medication use. Use of asthma medication attenuated the total estimated effect of asthma on obesity by 64% (excess hazard ratios = 0.64; 95% CI = -1.05, -0.23).

CONCLUSIONS

This nationwide study supports the hypothesis that childhood asthma is associated with later risk of obesity. Asthma medication may reduce this association and merits further investigation as a potential strategy for obesity prevention among children with asthma.

Prenatal exposure to air pollution is associated with childhood inhibitory control and adolescent academic achievement

BACKGROUND

Prenatal air pollution exposure is associated with reductions in self-regulation and academic achievement. Self-regulation has been separately linked with academic achievement. Understudied, however, are the contributions of pollution exposure to inhibitory control, a facet of self-regulation, and whether pollution-related inhibitory control deficits are associated with impairment in academic achievement.

METHODS

Participants were recruited from a prospective birth cohort. Measures of prenatal airborne polycyclic aromatic hydrocarbons (PAH) during the third trimester of pregnancy, inhibitory control (NEPSY Inhibition) at mean age = 10.4 years, and Woodcock-Johnson Tests of Achievement-III at mean age = 13.7 were available for N = 200 participants. Multiple linear regression examined sex-dependent and sex independent associations among prenatal PAH, childhood inhibitory control, and academic achievement during adolescence, and whether childhood inhibitory control mediated associations between prenatal PAH and academic achievement during adolescence, controlling for ethnicity, maternal country of birth, language of prenatal interview, maternal marital status, maternal years of education, material hardship, quality of home caregiving environment, and early life stress.

RESULTS

Across all participants, higher prenatal PAH was significantly associated with worse spelling skills (WJ-III Spelling, β = -0.16, 95%Confidence Interval [CI]: 0.30, -0.02, p = .02). Trend level associations between higher prenatal PAH and worse reading comprehension (WJ-III Passage Comprehension, β = -0.13, 95%CI: 0.28, 0.01, p = .07) and math skills (WJ-III Broad Math, β = -0.11, 95%CI: 0.25, 0.03, p = .11) were detected. Across all participants, higher PAH was significantly associated with worse inhibitory control (β = -0.15, 95%CI: 0.29,-0.01 p = .03). Better inhibitory control was significantly associated with better reading comprehension (WJ-III Passage Comprehension, β = 0.22, 95%CI: 0.09, 0.36, p < .002) and math skills (WJ-III Broad Math Index, β = 0.32, 95%CI: 0.19, 0.45, p < .001), and trend level associations with better spelling skills (WJ-III Spelling, β = 0.12, 95%CI: 0.02, 0.26, p = .10). Inhibitory control significantly mediated PAH-related achievement effects for Passage Comprehension (β = -0.61, 95%CI: 1.49, -0.01) and Broad Math Index (β = -1.09, 95%CI: 2.36, -0.03).

CONCLUSIONS

Higher prenatal PAH exposure and lower childhood inhibitory control were associated with worse spelling, passage comprehension, and math in adolescence. Notably, childhood inhibitory control mediated PAH exposure-related effects on achievement in adolescents. Identifying these potential exposure-related phenotypes of learning problems may promote interventions that target inhibitory control deficits rather than content specific deficits.

Exploring associations between prenatal exposure to multiple endocrine disruptors and birth weight with exposure continuum mapping

BACKGROUND

Improved understanding of how prenatal exposure to environmental mixtures influences birth weight or other adverse outcomes is essential in protecting child health.

OBJECTIVE

We illustrate a novel exposure continuum mapping (ECM) framework that combines the self-organizing map (SOM) algorithm with generalized additive modeling (GAM) in order to integrate spatially-correlated learning into the study mixtures of environmental chemicals. We demonstrate our method using biomarker data on chemical mixtures collected from a diverse mother-child cohort.

METHODS

We obtained biomarker concentrations for 16 prevalent endocrine disrupting chemicals (EDCs) collected in the first-trimester from a large, ethnically/racially diverse cohort of healthy pregnant women (n = 604) during 2009-2012. This included 4 organochlorine pesticides (OCPs), 4 polybrominated diphenyl ethers (PBDEs), 4 polychlorinated biphenyls (PCBs), and 4 perfluoroalkyl substances (PFAS). We applied a two-stage exposure continuum mapping (ECM) approach to investigate the combined impact of the EDCs on birth weight. First, we analyzed our EDC data with SOM in order to reduce the dimensionality of our exposure matrix into a two-dimensional grid (i.e., map) where nodes depict the types of EDC mixture profiles observed within our data. We define this map as the 'exposure continuum map', as the gridded surface reflects a continuous sequence of exposure profiles where adjacent nodes are composed of similar mixtures and profiles at more distal nodes are more distinct. Lastly, we used GAM to estimate a joint-dose response based on the coordinates of our ECM in order to capture the relationship between participant location on the ECM and infant birth weight after adjusting for maternal age, race/ethnicity, pre-pregnancy body mass index (BMI), education, serum cotinine, total plasma lipids, and infant sex. Single chemical regression models were applied to facilitate comparison.

RESULTS

We found that an ECM with 36 mixture profiles retained 70% of the total variation in the exposure data. Frequency analysis showed that the most common profiles included relatively low concentrations for most EDCs (~10%) and that profiles with relatively higher concentrations (for single or multiple EDCs) tended to be rarer (~1%) but more distinct. Estimation of a joint-dose response function revealed that lower birth weights mapped to locations where profile compositions were dominated by relatively high PBDEs and select OCPs. Higher birth weights mapped to locations where profiles consisted of higher PCBs. These findings agreed well with results from single chemical models.

CONCLUSIONS

Findings from our study revealed a wide range of prenatal exposure scenarios and found that combinations exhibiting higher levels of PBDEs were associated with lower birth weight and combinations with higher levels of PCBs and PFAS were associated with increased birth weight. Our ECM approach provides a promising framework for supporting studies of other exposure mixtures.

Telomere dynamics across the early life course: Findings from a longitudinal study in children

Telomeres are protective caps on chromosome ends that shorten with each cell division. Telomere length (TL) predicts the onset of cellular senescence and correlates with longevity and age-related disease risk. Previous research suggests that adults display fixed ranking and tracking of TL by age 20 years, supporting the importance of TL at birth and attrition during childhood. However, longitudinal research examining telomere dynamics during early life is sparse. Here, we used monochrome multiplex quantitative polymerase chain reaction to measure relative TL in leukocytes isolated from cord blood and child blood collected at ages 3, 5, 7, and 9 years among 224 minority children enrolled in a New York City-based birth cohort. We also measured maternal TL at delivery in a subset of 197 participants with a biobanked blood sample. TL decreased most rapidly in the first years of life (birth to 3 years), followed by a period of maintenance into the pre-puberty period. Mothers with longer telomeres gave birth to newborns with longer telomeres that remained longer across childhood, suggesting that the fixed ranking and tracking of TL observed among adults may extend to early childhood or even the prenatal period with a potential transgenerational basis. We did not find significant sex differences in the pattern of child TL change across development. These findings emphasize the need to understand factors and mechanisms that determine TL during early childhood.

Prenatal air pollution exposure and neurodevelopment: A review and blueprint for a harmonized approach within ECHO

BACKGROUND

Air pollution exposure is ubiquitous with demonstrated effects on morbidity and mortality. A growing literature suggests that prenatal air pollution exposure impacts neurodevelopment. We posit that the Environmental influences on Child Health Outcomes (ECHO) program will provide unique opportunities to fill critical knowledge gaps given the wide spatial and temporal variability of ECHO participants.

OBJECTIVES

We briefly describe current methods for air pollution exposure assessment, summarize existing studies of air pollution and neurodevelopment, and synthesize this information as a basis for recommendations, or a blueprint, for evaluating air pollution effects on neurodevelopmental outcomes in ECHO.

METHODS

We review peer-reviewed literature on prenatal air pollution exposure and neurodevelopmental outcomes, including autism spectrum disorder, attention deficit hyperactivity disorder, intelligence, general cognition, mood, and imaging measures. ECHO meta-data were compiled and evaluated to assess frequency of neurodevelopmental assessments and prenatal and infancy residential address locations. Cohort recruitment locations and enrollment years were summarized to examine potential spatial and temporal variation present in ECHO.

DISCUSSION

While the literature provides compelling evidence that prenatal air pollution affects neurodevelopment, limitations in spatial and temporal exposure variation exist for current published studies. As >90% of the ECHO cohorts have collected a prenatal or infancy address, application of advanced geographic information systems-based models for common air pollutant exposures may be ideal to address limitations of published research.

CONCLUSIONS

In ECHO we have the opportunity to pioneer unifying exposure assessment and evaluate effects across multiple periods of development and neurodevelopmental outcomes, setting the standard for evaluation of prenatal air pollution exposures with the goal of improving children's health.

Associations of prenatal exposure to polycyclic aromatic hydrocarbons with pubertal timing and body composition in adolescent girls: Implications for breast cancer risk

BACKGROUND

While animal data support an association between prenatal exposure to endocrine disrupting chemicals (EDCs) and altered mammary gland development and tumorigenesis, epidemiologic studies have only considered a few classes of EDCs in association with pubertal growth and development in girls. Polycyclic aromatic hydrocarbons (PAH) are a class of EDCs that have not been rigorously evaluated in terms of prenatal exposure and pubertal growth and development in girls.

OBJECTIVE

In a New York City birth cohort of Black and Hispanic girls (n = 196; recruited 1998-2006), we examined associations of prenatal PAH exposure with self-reported age at growth spurt onset, breast development onset and menarche, and clinical measures of adolescent body composition including body mass index, waist-to-hip ratio, and body fat measured at ages 11-20 years.

METHODS

We measured prenatal exposure to PAH using personal air monitoring data collected from backpacks worn by mothers during the third trimester of pregnancy (data available for all 196 girls) and biomarkers of benzo[α]pyrene-DNA adducts in umbilical cord blood (data available for 106 girls). We examined associations of prenatal PAH with the timing of pubertal milestones and adolescent body composition (11-20 years) using multivariable linear regression models adjusted for race/ethnicity, household public assistance status at birth, and age at outcome assessment. We also fit models further adjusted for potential mediators, including birthweight and childhood body size (BMI-for-age z-score measured at 6-8 years).

RESULTS

Girls in the highest versus lowest tertile of ambient exposure to PAH, based on a summary measure of eight carcinogenic higher-molecular weight non-volatile PAH compounds (Σ8 PAH), had a 0.90 year delay in growth spurt onset (95% confidence interval (CI) = 0.25, 1.55; n = 196), a 0.35 year delay in breast development onset (95% CI = -0.26, 0.95; n = 193), and a 0.59 year delay in menarche (95% CI = 0.06, 1.11; n = 191) in models adjusted for race/ethnicity and household public assistance at birth. The statistically significant associations for age at growth spurt onset and menarche were not impacted by adjustment for birthweight or childhood body size. No differences in BMI-for-age z-score, waist-to-hip ratio, or percent body fat were found between girls in the highest versus lowest tertile of ambient Σ8 PAH. Results were similar when we evaluated benzo[α]pyrene-DNA adduct levels.

DISCUSSION

Our results suggest that prenatal exposure to PAH might delay pubertal milestones in girls, but findings need to be replicated in other cohorts using prospectively collected data on pubertal outcomes.

Potential health benefits of sustained air quality improvements in New York City: A simulation based on air pollution levels during the COVID-19 shutdown

New York City (NYC) experienced a sharp decline in air pollution during the COVID-19 shutdown period (March 15, 2020 to May 15, 2020)-albeit at high social and economic costs. It provided a unique opportunity to simulate a scenario in which the city-wide air quality improvement during the shutdown were sustained over the five-year period, 2021 through 2025, allowing us to estimate the potential public health benefits to children and adults and their associated economic benefits. We focused on fine particulate matter (PM_2.5) and modeled potential future health benefits to children and adults. The analysis considered outcomes in children that have not generally been accounted for in clean air benefits assessments, including preterm birth, term low birthweight, infant mortality, child asthma incidence, child asthma hospital admissions and emergency department visits, autism spectrum disorder, as well as adult mortality. We estimated a city-wide 23% improvement in PM_2.5 levels during the COVID-19 shutdown months compared to the average level for those months in 2015-2018 (the business as usual period). Based on the data for 2020, we extrapolated the ambient levels of PM_2.5 for the following five-year period. The estimated cumulative benefits for 2021-2025 included thousands of avoided cases of illness and death, with associated economic benefits from $31.8 billion to $77 billion. This "natural experiment," tragic though the cause, has provided a hypothetical clean air scenario that can be considered aspirational-one that could be achieved through transportation, climate, and environmental policies that support robust economic recovery with similarly reduced emissions.

A methodological pipeline to generate an epigenetic marker of prenatal exposure to air pollution indicators

A barrier in the children's environmental health field has been the lack of early-warning systems to identify risks of childhood illness and developmental disorders. We aimed to develop a methodology to identify an accessible biomarker measured in a small amount of blood to distinguish newborns at elevated risk from a toxic prenatal exposure, using air pollutants as a case study. Because air pollutants are associated with altered DNA methylation, we developed a pipeline using DNA methylation signatures measured in umbilical cord blood, which could be used as predictors of prenatal exposure. We used air pollution indicators, including modelled trimester-specific and pregnancy average NO₂ and PM_2.5, and DNA methylation signatures from Illumina arrays measured in two New York City-based longitudinal birth cohorts from the Columbia Centre for Children's Environmental Health. We developed a screening plus three-part pipeline that incorporates selection, testing, and validation to identify whether DNA methylation can be used to predict exposure to prenatal air pollution indicators, NO₂ and PM_2.5. Applying this pipeline, we found that cord blood DNA methylation could be used to predict high vs. low average pregnancy NO₂ (AUC = 0.60, 95% CI: 0.52-0.68, with validation AUC = 0.60). Similar results were found for high vs. low third trimester NO₂. In this proof of concept study using air pollutants as an example, we provide an approach (with a generalizable analytic pipeline) that can be used for prediction of prenatal exposure to contaminants. This approach has potential to identify children at risk of developmental disorders and illness resulting from prenatal exposure.

Racial and geographic variation in effects of maternal education and neighborhood-level measures of socioeconomic status on gestational age at birth: Findings from the ECHO cohorts

Preterm birth occurs at excessively high and disparate rates in the United States. In 2016, the National Institutes of Health (NIH) launched the Environmental influences on Child Health Outcomes (ECHO) program to investigate the influence of early life exposures on child health. Extant data from the ECHO cohorts provides the opportunity to examine racial and geographic variation in effects of individual- and neighborhood-level markers of socioeconomic status (SES) on gestational age at birth. The objective of this study was to examine the association between individual-level (maternal education) and neighborhood-level markers of SES and gestational age at birth, stratifying by maternal race/ethnicity, and whether any such associations are modified by US geographic region. Twenty-six ECHO cohorts representing 25,526 mother-infant pairs contributed to this disseminated meta-analysis that investigated the effect of maternal prenatal level of education (high school diploma, GED, or less; some college, associate's degree, vocational or technical training [reference category]; bachelor's degree, graduate school, or professional degree) and neighborhood-level markers of SES (census tract [CT] urbanicity, percentage of black population in CT, percentage of population below the federal poverty level in CT) on gestational age at birth (categorized as preterm, early term, full term [the reference category], late, and post term) according to maternal race/ethnicity and US region. Multinomial logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CIs). Cohort-specific results were meta-analyzed using a random effects model. For women overall, a bachelor's degree or above, compared with some college, was associated with a significantly decreased odds of preterm birth (aOR 0.72; 95% CI: 0.61-0.86), whereas a high school education or less was associated with an increased odds of early term birth (aOR 1.10, 95% CI: 1.00-1.21). When stratifying by maternal race/ethnicity, there were no significant associations between maternal education and gestational age at birth among women of racial/ethnic groups other than non-Hispanic white. Among non-Hispanic white women, a bachelor's degree or above was likewise associated with a significantly decreased odds of preterm birth (aOR 0.74 (95% CI: 0.58, 0.94) as well as a decreased odds of early term birth (aOR 0.84 (95% CI: 0.74, 0.95). The association between maternal education and gestational age at birth varied according to US region, with higher levels of maternal education associated with a significantly decreased odds of preterm birth in the Midwest and South but not in the Northeast and West. Non-Hispanic white women residing in rural compared to urban CTs had an increased odds of preterm birth; the ability to detect associations between neighborhood-level measures of SES and gestational age for other race/ethnic groups was limited due to small sample sizes within select strata. Interventions that promote higher educational attainment among women of reproductive age could contribute to a reduction in preterm birth, particularly in the US South and Midwest. Further individual-level analyses engaging a diverse set of cohorts are needed to disentangle the complex interrelationships among maternal education, neighborhood-level factors, exposures across the life course, and gestational age at birth outcomes by maternal race/ethnicity and US geography.

Prenatal exposure to polycyclic aromatic hydrocarbons modifies the effects of early life stress on attention and Thought Problems in late childhood

BACKGROUND

Risk for childhood psychopathology is complex and multifactorial, implicating direct and interacting effects of familial and environmental factors. The role of environmental neurotoxicants in psychiatric risk is of growing concern, including polycyclic aromatic hydrocarbons (PAH), common in air pollution. Prenatal PAH exposure is linked to adverse physical, behavioral, and cognitive outcomes as well as increasing psychiatric risk. It is unclear whether environmental exposures, like PAH, magnify the effects of exposure to early life stress (ELS), a critical risk factor for psychopathology. The current work aimed to test potential interactions between prenatal PAH exposure and psychosocial/socioeconomic stress on psychiatric symptoms in school-age children.

METHODS

Data were from the Columbia Center for Children's Environmental Health Mothers and Newborns longitudinal birth cohort study. Prenatal PAH exposure was ascertained though air monitoring during pregnancy and maternal PAH-DNA adducts at delivery. Mothers reported on ELS (child age 5) and on child psychiatric symptoms across childhood (child age 5, 7, 9, and 11) using the Child Behavior Checklist (CBCL).

RESULTS

Significant prenatal airborne PAH × ELS interactions (FDR-corrected) predicted CBCL Attention (β = 0.22, t(307) = 3.47, p < .001, p_fdr  = .003) and Thought Problems T-scores (β = 0.21, t(307) = 3.29, p = .001, p_fdr  = .004) at age 11 (n = 319). Relative to those with lower exposure, children with higher prenatal PAH exposure exhibited stronger positive associations between ELS and CBCL Attention and Thought Problem T-scores. This interaction was also significant examining convergent ADHD measures (Conners, DuPaul) and examining maternal PAH-DNA adducts (β = 0.29, t(261) = 2.48, p = .01; n = 273). A three-way interaction with assessment wave indicated that the PAH × ELS interaction on Attention Problems was stronger later in development (β = 0.03, t(1,601) = 2.19, p = .03; n = 477).

CONCLUSIONS

Prenatal exposure to PAH, a common neurotoxicant in air pollution, may magnify or sustain the effects of early life psychosocial/socioeconomic stress on psychiatric outcomes later in child development. This work highlights the critical role of air pollution exposure on child mental health.

Guidelines for Modeling and Reporting Health Effects of Climate Change Mitigation Actions

BACKGROUND

Modeling suggests that climate change mitigation actions can have substantial human health benefits that accrue quickly and locally. Documenting the benefits can help drive more ambitious and health-protective climate change mitigation actions; however, documenting the adverse health effects can help to avoid them. Estimating the health effects of mitigation (HEM) actions can help policy makers prioritize investments based not only on mitigation potential but also on expected health benefits. To date, however, the wide range of incompatible approaches taken to developing and reporting HEM estimates has limited their comparability and usefulness to policymakers.

OBJECTIVE

The objective of this effort was to generate guidance for modeling studies on scoping, estimating, and reporting population health effects from climate change mitigation actions.

METHODS

An expert panel of HEM researchers was recruited to participate in developing guidance for conducting HEM studies. The primary literature and a synthesis of HEM studies were provided to the panel. Panel members then participated in a modified Delphi exercise to identify areas of consensus regarding HEM estimation. Finally, the panel met to review and discuss consensus findings, resolve remaining differences, and generate guidance regarding conducting HEM studies.

RESULTS

The panel generated a checklist of recommendations regarding stakeholder engagement: HEM modeling, including model structure, scope and scale, demographics, time horizons, counterfactuals, health response functions, and metrics; parameterization and reporting; approaches to uncertainty and sensitivity analysis; accounting for policy uptake; and discounting.

DISCUSSION

This checklist provides guidance for conducting and reporting HEM estimates to make them more comparable and useful for policymakers. Harmonization of HEM estimates has the potential to lead to advances in and improved synthesis of policy-relevant research that can inform evidence-based decision making and practice. https://doi.org/10.1289/EHP6745.

The associations between prenatal exposure to polycyclic aromatic hydrocarbon metabolites, umbilical cord blood mitochondrial DNA copy number, and children's neurobehavioral development

Exposure to polycyclic aromatic hydrocarbons (PAHs) during pregnancy is a risk factor for adverse neurobehavioral development outcomes. Mitochondrial DNA are sensitive to environmental toxicants due to the limited ability of repairing. The change of mitochondrial DNA copy number (mtDNAcn) might be a biologically mechanism linking PAH exposure and children's neurobehavioral impairment. Our aims are to explore whether PAH metabolites in maternal urine were associated with children's neurobehavioral development at 2 years old and umbilical cord blood mtDNAcn, and whether mtDNAcn was a mediator of PAH-related neurobehavioral development. We included 158 non-smoking pregnant women from Taiyuan City, Shanxi Province. Maternal urinary eleven PAH metabolites were detected by high performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS). MtDNAcn in cord blood was detected by real time quantitative polymerase chain reaction (RT-PCR). Children's neurodevelopment was measured by Gesell Developmental Schedules (GDS) when children were two years age. Generalized linear models and restricted cubic spline models were applied to assess the relationships between PAH metabolites in maternal urine and GDS scores and mtDNAcn. A mediation analysis was also conducted. Generalized linear models showed the relationships of sum of PAH metabolites (Σ-OHPAHs) in maternal urine with decreased motor score, and Σ-OHPAHs with increased mtDNAcn (p for trend < 0.05). Urinary levels of Ln (Σ-OHPAHs) increased one unit was related to a 2.08 decreased in motor scores, and Ln (Σ-OHPAHs) increased one unit was related to 0.15 increased in mtDNAcn. Mediation analysis did not find mtDNAcn can be a mediator between PAH metabolites and neurobehavioral development. Our results suggest that prenatal exposure to PAH decreased children's neurobehavioral development scores and increased mtDNAcn. And reducing exposure to PAH during pregnancy will benefit to improving neurobehavioral development in children. In our present cohort study, sum of PAH metabolites in urine of pregnant women were related with motor score and were positively associated with umbilical cord blood mtDNA copy number.

Co-Benefits to Children's Health of the U.S. Regional Greenhouse Gas Initiative

BACKGROUND

While various policies have been implemented globally to mitigate climate change and reduce exposure to toxic air pollutants, policy assessments have considered few if any of the benefits to children.

OBJECTIVE

To comprehensively assess the co-benefits of climate change mitigation to children, we expanded the suite of adverse health outcomes in the U.S. Environmental Protection Agency's Benefits Mapping and Analysis Program (BenMAP) to include additional outcomes associated with prenatal and childhood exposure to ambient fine particulate matter (PM2.5). We applied this newly expanded program to an assessment of the U.S. Regional Greenhouse Gas Initiative (RGGI), the United States' first regional market-based regulatory program designed to reduce greenhouse gas emissions from the electric power sector within the Northeast.

METHODS

We used calculated changes in ambient PM2.5 concentrations for the period 2009-2014, with newly incorporated concentration-response (C-R) functions to quantify changes in the incidence of preterm birth (PTB), term low birth weight (TLBW), autism spectrum disorder (ASD), and asthma. These outcomes are causally or likely to be causally related to PM2.5 exposure. Cost per case estimates were incorporated to monetize those changes in incidence.

RESULTS

The estimated avoided cases of adverse child health outcomes included 537 asthma cases, 112 preterm births, 98 cases of ASD, and 56 cases of TLBW, with an associated avoided cost estimate ranging from $191 to $350 million. In a previous analysis of health benefits of RGGI, the only benefits accruing to children were limited to prevented cases of infant mortality and respiratory illnesses, with a monetized impact of $8.1 million-only 2-4% of the new results attributable to RGGI.

CONCLUSION

The results of this innovative analysis indicate that RGGI has provided substantial child health benefits beyond those initially considered. Moreover, those health benefits had significant estimated economic value. https://doi.org/10.1289/EHP6706.

Towards a fuller assessment of the economic benefits of reducing air pollution from fossil fuel combustion: Per-case monetary estimates for children's health outcomes

BACKGROUND

Impacts on children's health are under-represented in benefits assessments of policies related to ambient air quality and climate change. To complement our previous compilation of concentration-response (C-R) functions for a number of children's health outcomes associated with air pollution, we provide per-case monetary estimates of the same health outcomes.

OBJECTIVES

Our goal was to establish per-case monetary estimates for a suite of prevalent children's health outcomes (preterm birth, low birth weight, asthma, autism spectrum disorder, attention-deficit/hyperactivity disorder, and IQ reduction) that can be incorporated into benefits assessments of air pollution regulations and climate change mitigation policies.

METHODS

We conducted a systematic review of the literature published between January 1, 2000 and June 30, 2018 to identify relevant economic costs for these six adverse health outcomes in children. We restricted our literature search to studies published in the U.S., with a supplemental consideration of studies from the U.K. and prioritized literature reviews with summary cost estimates and papers that provided lifetime cost of illness estimates.

RESULTS

Our literature search and evaluation process reviewed 1065 papers and identified 12 most relevant papers on per-case monetary estimates for preterm birth, low birth weight, asthma, autism spectrum disorder, and attention-deficit/hyperactivity disorder. Details are presented in full. We separately identified estimates of the lost lifetime earnings associated with the loss of a single IQ point. The final per-case cost estimates for each outcome were selected based on the most robust evidence. These estimates range from $23,573 for childhood asthma not persisting into adulthood to $3,109,096 for a case of autism with a concurrent intellectual disability.

CONCLUSION

To our knowledge, this is the first time that the child-specific health outcomes of preterm birth, low birth weight, asthma, autism spectrum disorder, attention-deficit/hyperactivity disorder, and IQ reduction have been systematically valued and presented in one place. This is an important addition to the body of health-related valuation literature as these outcomes have substantial economic costs that are not considered in most assessments of the benefits of air pollution and climate mitigation policies. In general, however, the available per-case estimates presented here did not incorporate the broad societal and long-term costs and are likely underestimates. Although our context has been air pollution and climate policies, the per-case monetary estimates presented here can be applied to other environmental exposures. Fuller assessments of health benefits to children and their corresponding economic gains will improve decision-making on environmental policy.

Prepregnancy obesity is associated with lower psychomotor development scores in boys at age 3 in a low-income, minority birth cohort

Whether maternal obesity and gestational weight gain (GWG) are associated with early-childhood development in low-income, urban, minority populations, and whether effects differ by child sex remain unknown. This study examined the impact of prepregnancy BMI and GWG on early childhood neurodevelopment in the Columbia Center for Children's Environmental Health Mothers and Newborns study. Maternal prepregnancy weight was obtained by self-report, and GWG was assessed from participant medical charts. At child age 3 years, the Psychomotor Development Index (PDI) and Mental Development Index (MDI) of the Bayley Scales of Infant Intelligence were completed. Sex-stratified linear regression models assessed associations between prepregnancy BMI and pregnancy weight gain z-scores with child PDI and MDI scores, adjusting for covariates. Of 382 women, 48.2% were normal weight before pregnancy, 24.1% overweight, 23.0% obese, and 4.7% underweight. At 3 years, mean scores on the PDI and MDI were higher among girls compared to boys (PDI: 102.3 vs. 97.2, P = 0.0002; MDI: 92.8 vs. 88.3, P = 0.0001). In covariate-adjusted models, maternal obesity was markedly associated with lower PDI scores in boys [b = -7.81, 95% CI: (-13.08, -2.55), P = 0.004], but not girls. Maternal BMI was not associated with MDI in girls or boys, and GWG was not associated with PDI or MDI among either sex (all-P > 0.05). We found that prepregnancy obesity was associated with lower PDI scores at 3 years in boys, but not girls. The mechanisms underlying this sex-specific association remain unclear, but due to elevated obesity exposure in urban populations, further investigation is warranted.

A powerful and flexible weighted distance-based method incorporating interactions between DNA methylation and environmental factors on health outcomes

MOTIVATION

Deoxyribonucleic acid (DNA) methylation plays a crucial role in human health. Studies have demonstrated associations between DNA methylation and environmental factors with evidence also supporting the idea that DNA methylation may modify the risk of environmental factors on health outcomes. However, due to high dimensionality and low study power, current studies usually focus on finding differential methylation on health outcomes at CpG level or gene level combining multiple CpGs and/or finding environmental effects on health outcomes but ignoring their interactions on health outcomes. Here we introduce the idea of a pseudo-data matrix constructed with cross-product terms between CpGs and environmental factors that are able to capture their interactions. We then develop a powerful and flexible weighted distance-based method with the pseudo-data matrix where association strength was used as weights on CpGs, environmental factors and their interactions to up-weight signals and down-weight noises in distance calculations.

RESULTS

We compared the power of this novel approach and several comparison methods in simulated datasets and the Mothers and Newborns birth cohort of the Columbia Center for Children's Environmental Health to determine whether prenatal polycyclic aromatic hydrocarbons interacts with DNA methylation in association with Attention Deficit Hyperactivity Disorder and Mental Development Index at age 3.

AVAILABILITY AND IMPLEMENTATION

An R code for the proposed method Dw-M-E-int together with a tutorial and a sample dataset is available for downloading from http://www.columbia.edu/∼sw2206/softwares.htm.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Characterizing peak exposure of secondhand smoke using a real-time PM2.5 monitor

Although short-duration elevated exposures (peak exposures) to pollutants may trigger adverse acute effects, epidemiological studies to understand their influence on different health effects are hampered by lack of methods for objectively identifying peaks. Secondhand smoke from cigarettes (SHS) in the residential environment can lead to peak exposures. The aim of this study was to explore whether peaks in continuous PM2.5 data can indicate SHS exposure. A total of 41 children (21 with and 20 without SHS exposure based on self-report) from 28 families in New York City (NY, USA) were recruited. Both personal and residential continuous PM2.5 monitoring were performed for five consecutive days using MicroPEM sensors (RTI International, USA). A threshold detection method based on cumulative distribution function was developed to identify peaks. When children were home, the mean accumulated peak area (APA) for peak exposures was 297 ± 325 hour*µg/m3 for children from smoking families and six times that of the APA from non-smoking families (~50 ± 54 hour*µg/m3 ). Average PM2.5 mass concentrations for SHS exposed and unexposed children were 24 ± 15 µg/m3 and 15 ± 9 µg/m3 , respectively. The average SHS exposure duration represents ~5% of total exposure time, but ~13% of children's total PM2.5 exposure dose, equivalent to an additional 2.6 µg/m3 per day. This study demonstrated the feasibility of peak analysis for quantifying SHS exposure. The developed method can be adopted more widely to support epidemiology studies on impacts of short-term exposures.

Prepregnancy obesity is associated with cognitive outcomes in boys in a low-income, multiethnic birth cohort

Background

Maternal obesity and high gestational weight gain (GWG) disproportionally affect low-income populations and may be associated with child neurodevelopment in a sex-specific manner. We examined sex-specific associations between prepregnancy BMI, GWG, and child neurodevelopment at age 7.

Methods

Data are from a prospective low-income cohort of African American and Dominican women (n = 368; 44.8% male offspring) enrolled during the second half of pregnancy from 1998 to 2006. Neurodevelopment was measured using the Wechsler Intelligence Scale for Children (WISC-IV) at approximately child age 7. Linear regression estimated associations between prepregnancy BMI, GWG, and child outcomes, adjusting for race/ethnicity, marital status, gestational age at delivery, maternal education, maternal IQ and child age.

Results

Overweight affected 23.9% of mothers and obesity affected 22.6%. At age 7, full-scale IQ was higher among girls (99.7 ± 11.6) compared to boys (96.9 ± 13.3). Among boys, but not girls, prepregnancy overweight and obesity were associated with lower full-scale IQ scores [overweight β: − 7.1, 95% CI: (− 12.1, − 2.0); obesity β: − 5.7, 95% CI: (− 10.7, − 0.7)]. GWG was not associated with full-scale IQ in either sex.

Conclusions

Prepregnancy overweight and obesity were associated with lower IQ among boys, but not girls, at 7 years. These findings are important considering overweight and obesity prevalence and the long-term implications of early cognitive development.

Maturation of Brain Microstructure and Metabolism Associates with Increased Capacity for Self-Regulation during the Transition from Childhood to Adolescence

Children ages 9-12 years face increasing social and academic expectations that require mastery of their thoughts, emotions, and behavior. Little is known about the development of neural pathways integral to these improving capacities during the transition from childhood to adolescence. Among 234 healthy, inner-city male and female youth (species Homo sapiens) 9-12 years of age followed by the Columbia Center for Children's Environmental Health, we acquired diffusion tensor imaging, multiplanar chemical shift imaging, and cognitive measures requiring self-regulation. We found that increasing age was associated with increased fractional anisotropy and decreased apparent diffusion coefficient, most prominently in the frontal and cingulate cortices, striatum, thalamus, deep white matter, and cerebellum. Additionally, we found increasing age was associated with increased N-acetyl-l-aspartate (NAA) in the anterior cingulate and insular cortices, and decreased NAA in posterior cingulate and parietal cortices. Age-associated changes in microstructure and neurometabolite concentrations partially mediated age-related improvements in performance on executive function tests. Together, these findings suggest that maturation of key regions within cortico-striatal-thalamo-cortical circuits subserve the emergence of improved self-regulatory capacities during the transition from childhood to adolescence.SIGNIFICANCE STATEMENT Few imaging studies of normal brain development have focused on a population of inner-city, racial/ethnic minority youth during the transition from childhood to adolescence, a period when self-regulatory capacities rapidly improve. We used DTI and MPCSI to provide unique windows into brain maturation during this developmental epoch, assessing its mediating influences on age-related improvement in performance on self-regulatory tasks. Our findings suggest that rapid maturation of cortico-striato-thalamo-cortical circuits, represented as progressive white-matter maturation (increasing FA and increasing NAA, Ch, Cr concentrations accompanying advancing age) in frontal regions and related subcortical projections and synaptic pruning (decreasing NAA, Ch, Cr, Glx) in posterior regions, support age-related improvements in executive functioning and self-regulatory capacities in youth 9-12 years of age.

Prenatal exposure to airborne polycyclic aromatic hydrocarbons and childhood growth trajectories from age 5-14 years

There is evidence that exposures to polycyclic aromatic hydrocarbons (PAH) and fine particles in air pollution are associated with higher childhood body mass index (BMI). Birth cohort analyses of prenatal exposures to PAH and child BMI Z-scores from age 5-14 years were conducted. African-American and Hispanic children born in the Bronx or Northern Manhattan, New York (1998-2006), whose mothers underwent personal air monitoring for airborne PAH exposure during pregnancy, were followed up with measurements of height and weight at approximate ages 5, 7, 9, 10, 11, 12.5 and 13.5 years. Multivariable generalized estimating equation analyses were used to relate prenatal airborne PAH exposures to child BMI Z-scores through time. The analyses adjusted for many known risk factors for childhood obesity and included interactions terms between age and exposure tertiles and age squared and exposure tertiles. In total, 535 children had at least one height and weight measure during follow-up. The prevalence of obesity was 20.6% at age 5 and increased across follow-ups until age 11 when it was 33.0%. At age 5, BMI Z-scores were significantly greater for children in the third tertile of exposure relative to the first tertile (0.35 Z-score units, 95% CI 0.09, 0.61, p = 0.007) and were non-significantly higher for the second tertile of exposure compared to the first tertile (0.25 Z-score units, 95% CI -0.02, 0.52, P = 0.075). The trajectories of BMI Z-scores by tertiles of exposure converged as the children aged, such that by age 11 years the estimated mean BMI Z-scores associated with each tertile of exposure were not different. Prenatal exposures to airborne PAH were associated with higher childhood BMI Z-scores at a young age, but growth trajectories converged by age 11 years. Accordingly, highly exposed children spend a greater proportion of their childhood with higher BMI Z-scores.

Towards a fuller assessment of benefits to children's health of reducing air pollution and mitigating climate change due to fossil fuel combustion

BACKGROUND

Fossil fuel combustion by-products, including particulate matter (PM_2.5), polycyclic aromatic hydrocarbons (PAH), nitrogen dioxide (NO₂) and carbon dioxide (CO₂), are a significant threat to children's health and equality. Various policies to reduce emissions have been implemented to reduce air pollution and mitigate climate change, with sizeable estimated health and economic benefits. However, only a few adverse outcomes in children have been considered, resulting in an undercounting of the benefits to this vulnerable population.

OBJECTIVES

Our goal was to expand the suite of child health outcomes addressed by programs to assess health and economic benefits, such as the Environmental Protection Agency (EPA) Benefits Mapping and Analysis Program (BenMAP), by identifying concentration-response (C-R) functions for six outcomes related to PM_2.5, NO₂, PAH, and/or PM₁₀: preterm birth (PTB), low birthweight (LBW), autism, attention deficit hyperactivity disorder, IQ reduction, and the development of childhood asthma.

METHODS

We conducted a systematic review of the literature published between January 1, 2000 and April 30, 2018 to identify relevant peer-reviewed case-control and cohort studies and meta-analyses. In some cases meta-analyses were available that provided reliable C-R functions and we assessed their consistency with subsequent studies. Otherwise, we reviewed all eligible studies published between our search dates.

RESULTS

For each pollutant and health outcome, we present the characteristics of each selected study. We distinguish between C-R functions for endpoints having a causal or likely relationship (PTB, LBW, autism, asthma development) with the pollutants for incorporation into primary analyses and endpoints having a suggestive causal relationship with the pollutants (IQ reduction, ADHD) for secondary analyses.

CONCLUSION

We have identified C-R functions for a number of adverse health outcomes in children associated with air pollutants largely from fossil fuel combustion. Their incorporation into expanded assessments of health benefits of clean air and climate mitigation policies will provide an important incentive for preventive action.

Healthy Air, Healthy Brains: Advancing Air Pollution Policy to Protect Children's Health

Evidence is growing on the adverse neurodevelopmental effects of exposure to combustion-related air pollution. Project TENDR (Targeting Environmental Neurodevelopmental Risks), a unique collaboration of leading scientists, health professionals, and children's and environmental health advocates, has identified combustion-related air pollutants as critical targets for action to protect healthy brain development. We present policy recommendations for maintaining and strengthening federal environmental health protections, advancing state and local actions, and supporting scientific research to inform effective strategies for reducing children's exposures to combustion-related air pollution. Such actions not only would improve children's neurological development but also would have the important co-benefit of climate change mitigation and further improvements in other health conditions.

Maternal urinary 2-hydroxynaphthalene and birth outcomes in Taiyuan, China

BACKGROUND

Naphthalene is the simplest polycyclic aromatic hydrocarbon (PAH). It is easily emitted into the atmosphere, posing a significant risk to human health. However, limited studies have described the impact of naphthalene exposure on birth outcomes. In this study, we investigated the association between the maternal urinary metabolites of naphthalene, 2-hydroxynaphthalene (2-OH NAP), and birth outcomes.

METHOD

In the present study, four urinary PAH metabolites were measured in 263 pregnant women during late pregnancy. Multiple linear regression analysis was used to analyze the relationship between the concentrations of 2-OH NAP and birth outcomes, and restricted cubic spline models were further used to examine the shapes of the dose-response association.

RESULT

General linear models showed that prenatal urinary 2-OH NAP was associated with lower birth weight (BW) (- 4.38% for the high vs. low exposure group of 2-OH NAP; p for trend = 0.049) and higher cephalization index (CI) (4.30% for the high vs. low exposure group of 2-OH NAP; p for trend = 0.038). These associations were linear and significant when 2-OH NAP was modeled as a continuous variable in restricted cubic spline models (P _linear = 0.0293 for 2-OH NAP and BW; P _linear = 0.0326 for 2-OH NAP and CI). Multiple linear regression data indicated that each 1 ln-unit increase in 2-OH NAP was significantly associated with a 2.09 g/cm increase in the CI. The associations among 2-OH NAP, BW, and CI were also observed in a subset of participants residing close to arterial traffic.

CONCLUSION

Our data indicated that prenatal exposure to naphthalene had an adverse effect on fetal birth outcomes, especially the brain development index. Reduced exposure to naphthalene may improve newborn health outcomes. In Taiyuan, naphthalene may result from traffic pollution.

Associations between prenatal and childhood PBDE exposure and early adolescent visual, verbal and working memory

BACKGROUND

Prenatal and childhood exposure to polybrominated diphenyl ether (PBDE) flame retardants has been inversely associated with cognitive performance, however, few studies have measured PBDE concentrations in samples collected during both prenatal and postnatal periods.

METHODS

We examined prenatal (cord) and childhood (ages 2, 3, 5, 7 and 9 years) plasma PBDE concentrations in relation to memory outcomes assessed between the ages of 9 and 14 years. The study sample includes a subset (n = 212) of the African American and Dominican children enrolled in the Columbia Center for Children's Environmental Health Mothers and Newborns birth cohort. We used multivariable linear regression to examine associations between continuous log₁₀-transformed PBDE concentrations and performance on tests of visual, verbal and working memory in age-stratified models. We additionally used latent class growth analysis to estimate trajectories of exposure across early life, which we analyzed as a categorical variable in relation to memory outcomes. We examined interactions between PBDE exposure and sex using cross-product terms.

RESULTS

Associations between prenatal exposure and working memory significantly varied by sex (p-interaction = 0.02), with inverse relations observed only among girls (i.e. β_BDE-47 = -7.55, 95% CI: -13.84, -1.24). Children with sustained high concentrations of BDEs-47, 99 or 100 across childhood scored approximately 5-8 standard score points lower on tests of visual memory. Children with PBDE plasma concentrations that peaked during toddler years performed better on verbal domains, however, these associations were not statistically significant.

CONCLUSIONS

Exposure to PBDEs during both prenatal and postnatal periods may disrupt memory domains in early adolescence. These findings contribute to a substantial body of evidence supporting the developmental neurotoxicity of PBDEs and underscore the need to reduce exposure among pregnant women and children.

Shorter telomere length in cord blood associated with prenatal air pollution exposure: Benefits of intervention

BACKGROUND

To examine the molecular benefits of the government action to close the local coal burning power plant in Tongliang County, Chongqing Municipality, we compared biologic markers and health outcomes in two successive birth cohorts enrolled before and after the plant was shut down. In this city, polycyclic aromatic hydrocarbons (PAH) were primarily emitted by the coal burning facility. We previously reported that cord blood levels of PAH-DNA adducts (a biomarker of exposure) and various adverse health outcomes were reduced in the second cohort, whereas levels of brain-derived neurotrophic factor/BDNF (a protein involved in neuronal growth) were increased. Here we assessed telomere length (TL), which has been associated with risk of certain chronic diseases, early mortality, aging and cognitive decline in adults.

OBJECTIVES

The goals of the present study were to determine whether TL differed between the two cohorts and whether prenatal PAH exposure, estimated by PAH-DNA adducts in cord white blood cells of newborns in China, were predictive of shorter TL in cord blood, suggesting the potential accrual of risk of certain chronic diseases during the prenatal period. We explored relationships of TL with BDNF and neurodevelopmental outcomes, each previously associated with PAH-DNA adducts in these cohorts, as well as the potential mediating role of TL in the associations between adducts and neurodevelopmental outcomes.

METHODS

We analyzed TL in cord blood of 255 newborns who also had data on PAH-DNA adducts, BDNF, and relevant covariates. Multiple regression analysis was carried out to test associations between adducts and TL and between TL and BDNF, adjusting for relevant covariates. In the subset with developmental quotient (DQ) scores from Gesell testing at age 2 (N = 210), we explored whether TL was a mediator of the relationship between PAH-DNA adducts and DQ scores by first examining the associations between cord adducts and DQ, cord adducts and TL, and TL and DQ, adjusting for the same covariates.

RESULTS

As hypothesized, the mean TL was significantly higher in the second cohort compared to the first cohort. Overall, PAH-DNA cord adducts were significantly and inversely correlated with TL. Multiple regression analysis showed a significant association between adducts and TL, after adjusting for key covariates: β (effect size per standard deviation adducts) = -0.019, p = .003. The regression coefficient of TL on (Ln) BDNF was also significant (β = 0.167, p < .001). Exploratory analysis, regressing TL on Gesell developmental scores, showed generally inverse, but not significant associations. TL was not, therefore, deemed to be a potential mediator of the association between adducts and developmental scores at age two.

CONCLUSION

This study provides the first evidence that prenatal PAH exposure from coal burning may adversely affect TL, with potential implications for future risk of chronic diseases including cardiovascular disease. The improvement in TL in the second cohort and the observed correlation between increased TL and higher levels of BDNF indicate direct benefits to the health and development of children resulting from the government's closure of the power plant.

A novel method for source-specific hemoglobin adducts of nitro-polycyclic aromatic hydrocarbons

Polycyclic aromatic hydrocarbons (PAH) are ubiquitous air pollutants associated with negative impacts on growth, development and behavior in children. Source-specific biological markers of PAH exposure are needed for targeting interventions to protect children. Nitro-derivatives of PAH can act as markers of exposure to diesel exhaust, gasoline exhaust, or general combustion sources. Using a novel HPLC-APCI-MS/MS detection method, we examined four hemoglobin (Hb) adducts of nitro-PAH metabolites and the Hb adduct of a benzo[a]pyrene (BaP) metabolite in 22 umbilical cord blood samples. The samples were collected from a birth cohort with comprehensive data on prenatal PAH exposure, including prenatal personal air monitoring and DNA adducts in maternal and umbilical cord blood. Using non-parametric analyses, heat maps, and principal component analysis (PCA), we analyzed the relationship between the five Hb adducts and previous PAH measurements, with each measurement representing a different duration of exposure. We found that Hb adducts derived from several diesel-related nitro-PAHs (2-nitrofluorene and 1-nitropyrene) were significantly correlated (r = 0.77, p ≤ 0.0001) and grouped together in PCA. Nitro-PAH derived Hb adducts were largely unrelated to previously collected measures of exposure to a number of PAH parent compounds. These measures need to be validated in a larger sample.

Pollution from Fossil-Fuel Combustion is the Leading Environmental Threat to Global Pediatric Health and Equity: Solutions Exist

Fossil-fuel combustion by-products are the world's most significant threat to children's health and future and are major contributors to global inequality and environmental injustice. The emissions include a myriad of toxic air pollutants and carbon dioxide (CO₂), which is the most important human-produced climate-altering greenhouse gas. Synergies between air pollution and climate change can magnify the harm to children. Impacts include impairment of cognitive and behavioral development, respiratory illness, and other chronic diseases-all of which may be "seeded" in utero and affect health and functioning immediately and over the life course. By impairing children's health, ability to learn, and potential to contribute to society, pollution and climate change cause children to become less resilient and the communities they live in to become less equitable. The developing fetus and young child are disproportionately affected by these exposures because of their immature defense mechanisms and rapid development, especially those in low- and middle-income countries where poverty and lack of resources compound the effects. No country is spared, however: even high-income countries, especially low-income communities and communities of color within them, are experiencing impacts of fossil fuel-related pollution, climate change and resultant widening inequality and environmental injustice. Global pediatric health is at a tipping point, with catastrophic consequences in the absence of bold action. Fortunately, technologies and interventions are at hand to reduce and prevent pollution and climate change, with large economic benefits documented or predicted. All cultures and communities share a concern for the health and well-being of present and future children: this shared value provides a politically powerful lever for action. The purpose of this commentary is to briefly review the data on the health impacts of fossil-fuel pollution, highlighting the neurodevelopmental impacts, and to briefly describe available means to achieve a low-carbon economy, and some examples of interventions that have benefited health and the economy.

Significant interactions between maternal PAH exposure and single nucleotide polymorphisms in candidate genes on B[ a ]P-DNA adducts in a cohort of non-smoking Polish mothers and newborns

Polycyclic aromatic hydrocarbons (PAH) are a class of chemicals common in the environment. Certain PAH are carcinogenic, although the degree to which genetic variation influences susceptibility to carcinogenic PAH remains unclear. Also unknown is the influence of genetic variation on the procarcinogenic effect of in utero exposures to PAH. Benzo[ a ]pyrene (B[ a ]P) is a well-studied PAH that is classified as a known human carcinogen. Within our Polish cohort, we explored interactions between maternal exposure to airborne PAH during pregnancy and maternal and newborn single nucleotide polymorphisms (SNPs) in plausible B[ a ]P metabolism genes on B[ a ]P-DNA adducts in paired cord blood samples. The study subjects included non-smoking women ( n = 368) with available data on maternal PAH exposure, paired cord adducts, and genetic data who resided in Krakow, Poland. We selected eight common variants in maternal and newborn candidate genes related to B[ a ]P metabolism, detoxification, and repair for our analyses: CYP1A1 , CYP1A2 , CYP1B1 , GSTM1 , GSTT2 , NQO1 , and XRCC1 . We observed significant interactions between maternal PAH exposure and SNPs on cord B[ a ]P-DNA adducts in the following genes: maternal CYP1A1 and GSTT2 , and newborn CYP1A1 and CYP1B1 . These novel findings highlight differences in maternal and newborn genetic contributions to B[ a ]P-DNA adduct formation and have the potential to identify at-risk subpopulations who are susceptible to the carcinogenic potential of B[ a ]P.

Environmental Pollutants and Neurodevelopment: Review of Benefits From Closure of a Coal-Burning Power Plant in Tongliang, China

Background. Understanding preventable causes of neurodevelopmental disorders is a public health priority. Polycyclic aromatic hydrocarbons (PAH) from combustion of fossil fuel, lead, and mercury are among known neurodevelopmental toxicants. Method. For the first time, we comprehensively review the findings from a study by the Columbia Center for Children's Environmental Health and Chinese partners that followed 2 groups of mother-child pairs, one from 2002 and another from 2005, in Tongliang County, China. Pregnant mothers in the 2 cohorts experienced different exposure to PAH because a local coal-burning power plant was shut down in 2004. Investigators assessed change in prenatal PAH exposure, measured using a biomarker (benzo[a]pyrene [BaP]-DNA adducts in cord blood). Developmental quotients were measured using the Gesell Developmental Scales at age 2 and IQ was assessed using the Wechsler Intelligence Scale for Children at age 5. Biologic markers of preclinical response were measured in cord blood: methylation status of long interspersed nuclear elements (LINE1), an indicator of genomic stability, and brain-derived neurotrophic factor (BDNF), a neuronal growth promoter. Analyses accounted for co-exposure to lead and mercury. Results. BaP-DNA adducts were significantly inversely associated with Gesell Developmental Scales scores in the first cohort but not in the second cohort; and levels of BDNF and LINE1 methylation were higher in the second cohort. Conclusion. In this study, reduced exposure to PAH was associated with beneficial effects on neurodevelopment as well as molecular changes related to improved brain development and health. These benefits should encourage further efforts to limit exposure to these toxic pollutants.