Critical Time Windows for Air Pollution Exposure and Birth Weight in a Multicity Canadian Pregnancy Cohort

Association between prenatal air pollutant exposure and autism spectrum disorders in young children: A matched case-control study in Canada

The direction and magnitude of association between maternal exposure to ambient air pollutants across gestational windows and offspring risk of autism spectrum disorders (ASD) remains unclear. We sought to evaluate the time-varying effects of prenatal air pollutant exposure on ASD. We conducted a matched case-control study of singleton term children born in Ontario, Canada from 1-Apr-2012 to 31-Dec-2016. Provincial birth registry data were linked with applied behavioural analysis services and ambient air pollutant datasets to ascertain prenatal exposure to nitrogen dioxide (NO2), ground-level ozone (O3), fine particulate matter (PM2.5), and ASD diagnoses. Covariate balance between cases and controls was established using coarsened exact matching. Conditional logistic regression was used to assess the association between prenatal air pollutant exposure and ASD. Distributed lag non-linear models (DLNM) were used to examine the effects of single-pollutant exposure by prenatal week. Sensitivity analyses were conducted to assess the impact of exposure period on the observed findings. The final sample included 1589 ASD cases and 7563 controls. Compared to controls, cases were more likely to be born to mothers living in urban areas, delivered by Caesarean section, and assigned male sex at birth. NO2 was a consistent and significant contributor to ASD risk after accounting for co-exposure to O3, PM2.5 and covariates. The odds ratio per interquartile range increase was 2.1 (95%CI 1.8-2.3) pre-conception, 2.2 (2.0-2.5) for the 1st trimester, 2.2 (1.9-2.5) for the 2nd trimester, and 2.1 (1.9-2.4) for the 3rd trimester. In contrast, findings for O3 and PM2.5 with ASD were inconsistent. Findings from DLNM and sensitivity analyses were similar. Exposure to NO2 before and during pregnancy was significantly associated with ASD in offspring. The relationship between prenatal O3 and PM2.5 exposure and ASD remains unclear. Further investigation into the combined effects of multi-pollutant exposure on child neurodevelopment is warranted.

Air pollution-linked epigenetic modifications in placental DNA: Prognostic potential for identifying future foetal anomalies

Prenatal exposure to air pollution is a significant risk factor for the mother and the developing foetus. The accumulation of pollutants in the placenta can cause a self-cascade loop of pro-inflammatory cytokine responses and DNA double-strand breaks. Previous research has shown that airborne particulate matter can damage the epigenome and disturb mitochondrial machinery, ultimately impairing placental function. Mitochondria are essential for preserving cellular homeostasis, energy metabolism, redox equilibrium, and epigenetic reprogramming. As these organelles are subtle targets of environmental exposures, any disruption in the signaling pathways can result in epigenomic instability, which can impact gene expression and mitochondrial function. This, in turn, can lead to changes in DNA methylation, post-translational histone modifications, and aberrant expression of microRNAs in proliferating trophoblast cells. The placenta has two distinct layers, cytotrophoblasts, and syncytiotrophoblasts, each with its mitochondria, which play important roles in preeclampsia, gestational diabetes, and overall health. Foetal nucleic acids enter maternal circulation during placental development because of necrotic, apoptotic, and inflammatory mechanisms. These nucleic acids reflect normal or abnormal ongoing cellular changes during prenatal foetal development. Detecting cell-free DNA in the bloodstream can be a biomarker for predicting negative pregnancy-related outcomes and recognizing abnormalities in foetal growth. Hence, a thorough understanding of how air pollution induces epigenetic variations within the placenta could offer crucial insights into underlying mechanisms and prolonged repercussions on foetal development and susceptibility in later stages of life.

Association between trimester-specific prenatal air pollution exposure and placental weight of twins

INTRODUCTION

This study investigates the association between maternal exposure to particulate matter (PM10) and nitric dioxide (NO2) during the first, second and third trimester and placental weight and birth weight/placental weight (BW/PW) ratio in twins at birth.

METHODS

Cross-sectional data of 3340 twins from the East Flanders Prospective Twin Survey was used. Air pollutant exposure was estimated via spatial temporal interpolation. Univariable and multivariable mixed model analyses with a random intercept to account for the relatedness of newborns were conducted for twins with separate placentas. Twin pairs with one placental mass were studied with linear and logistic regression.

RESULTS

In the third trimester, for each 10 μm/m3 increase in PM10 or NO2 placental weight decreased -19.7 g (95%-C.I. -35.1; -4.3) and -17.7 g (95%-C.I. -30.4; -0.5) respectively, in moderate to late preterm twins with separate placentas. Consequently, BW/PW ratio increased with higher air pollution exposure. PM10 exposure in the last week of pregnancy was associated with a higher odds ratio (OR) of 1.20 (95%-C.I. 1.00; 1.44) for a "small for gestational age placenta" (placental weight <10th percentile). Conversely, first trimester air pollutant exposure was associated with lower ORs of 0.55 (95%-C.I. 0.35; 0.88) and 0.60 (95%-C.I. 0.42; 0.84).

DISCUSSION

The association of PM10 and NO2 on placental weight is trimester-specific, differs for twins with one versus two placentas and is most pronounced in moderate to late preterm twins. Longitudinal studies are needed to better understand the relationship between air pollutant exposure and placental weight evolution across different trimesters.

Associations of neighborhood greenspace, and active living environments with autism spectrum disorders: A matched case-control study in Ontario, Canada

BACKGROUND

Increasing evidence links early life residential exposure to natural urban environmental attributes and positive health outcomes in children. However, few studies have focused on their protective effects on the risk of autism spectrum disorder (ASD). The aim of this study was to investigate the associations of neighborhood greenspace, and active living environments during pregnancy with ASD in young children (≤6 years).

METHODS

We conducted a population-based matched case-control study of singleton term births in Ontario, Canada for 2012-2016. The ASD and environmental data was generated using the Ontario Autism Spectrum Profile, the Better Outcomes Registry & Network Ontario, and Canadian Urban Environmental Health Research Consortium. We employed conditional logistic regressions to estimate the odds ratio (OR) between ASD and environmental factors characterizing selected greenspace metrics and neighborhoods conducive to active living (i.e., green view index (GVI), normalized difference vegetation index (NDVI), tree canopy, park proximity and active living environments index (ALE)).

RESULTS

We linked 8643 mother-child pairs, including 1554 cases (18%). NDVI (OR 1.034, 0.944-1.024, per Inter Quartile Range [IQR] = 0.08), GVI (OR 1.025, 95% CI 0.953-1.087, per IQR = 9.45%), tree canopy (OR 0.992, 95% CI 0.903-1.089, per IQR = 6.24%) and the different categories of ALE were not associated with ASD in adjusted models for air pollution. In contrast, living closer to a park was protective (OR 0.888, 0.833-0.948, per 0.06 increase in park proximity index), when adjusted for air pollution.

CONCLUSIONS

This study reported mixed findings showing both null and beneficial effects of green spaces and active living environments on ASD. Further investigations are warranted to elucidate the role of exposure to greenspaces and active living environments on the development of ASD.

A cohort study of the multipollutant effects of PM2.5, NO2, and O3 on C-reactive protein levels during pregnancy

Background

PM2.5, NO2, and O3 contribute to the development of adverse pregnancy complications. While studies have investigated the independent effects of these exposures, literature on their combined effects is limited. Our objective was to study the multipollutant effects of PM2.5, NO2, and O3 on maternal systemic C-reactive protein (CRP) levels.

Methods

We used data from 1170 pregnant women enrolled in the Maternal-Infant Research on Environmental Chemicals Study (MIREC) study in Canada. Air pollution exposures were assigned to each participant based on residential location. CRP was measured in third-trimester blood samples. We fit multipollutant linear regression models and evaluated the effects of air pollutant mixtures (14-day averages) using repeated-holdout Weighted Quantile Sum (WQS) regression and by calculating the Air Quality Health Index (AQHI).

Results

In multipollutant models adjusting for NO2, O3, and green space, each interquartile range (IQR) increase in 14-day average PM2.5 (IQR: 6.9 µg/m3) was associated with 27.1% (95% confidence interval [CI] = 6.2, 50.7) higher CRP. In air pollution mixture models adjusting for green space, each IQR increase in AQHI was associated with 37.7% (95% CI = 13.9, 66.5) higher CRP; and an IQR increase in the WQS index was associated with 78.6% (95% CI = 29.7, 146.0) higher CRP.

Conclusion

PM2.5 has the strongest relationship of the individual pollutants examined with maternal blood CRP concentrations. Mixtures incorporating all three pollutants, assessed using the AQHI and WQS index, showed stronger relationships with CRP compared with individual pollutants and illustrate the importance of conducting multipollutant analyses.

Windows of sensitivity for risk of adverse birth outcomes related to gestational PM2.5 exposure: Evidence from a natural experiment

While numerous studies have associated maternal exposure to PM2.5 with adverse birth outcomes, findings remain inconsistent and difficult to generalize. We aimed to investigate the causal relationship and window of sensitivity between gestational exposure to PM2.5 and birth outcomes. We leveraged high-resolution satellite data to quantify gestational PM2.5 exposure at the individual level, along with a combined model to determine daily relative risks (RRs) of birth outcomes in COVID-19 prelockdown and lockdown groups. RRs between the two groups were further compared using a longitudinal pre-post non-experimental design to identify sensitivity windows of adverse birth outcomes. A total of 73,781 pregnant women from the COVID-19 prelockdown group and 6267 pregnant women from the lockdown group were included for analysis. The daily mean PM2.5 concentrations in the lockdown group decreased by 21.7% compared to the prelockdown group. During the first trimester, every 10 μg/m3 increase in PM2.5 significantly increased the risk of congenital abnormalities of major organs such as the cardiovascular system, gastrointestinal tract, nervous system, urinary system, and respiratory system. Moreover, gestational exposure to PM2.5 during the first trimester was associated with higher risks of premature delivery and term low birth weight. While PM2.5 exposure during the second trimester was positively correlated with macrosomia. Gestational exposure to PM2.5 is associated with increased risks of various adverse birth outcomes with specific sensitive windows. We demonstrated that gestational exposure to PM2.5 increased risks of various adverse birth outcomes with specific window of sensitivity through the natural experiment design. Our findings underscore the urgent need for policies and initiatives targeting PM2.5 reduction, especially during critical periods of pregnancy.

Prenatal exposure to air pollution and BWGA Z-score: Modifying effects of placenta leukocyte telomere length and infant sex

BACKGROUND

Air pollutants, such as fine particulate matter (PM2.5), nitrogen dioxide (NO2), and ozone (O3), have been associated with adverse birth outcomes, including low birth weight, often exhibiting sex-specific effects. However, the modifying effect of placental telomere length (TL), reflecting cumulative lifetime oxidative stress in mothers, remains unexplored.

METHOD

Using data from a Northeastern U.S. birth cohort (n = 306), we employed linear regression and weighted quantile sum models to assess trimester-average air pollution exposures and birth weight for gestational age (BWGA) z-scores. Placental TL, categorized by median split, was considered as an effect modifier. Interactions among air pollutants, placental TL, infant sex, and BWGA z-score were evaluated.

RESULTS

Without placental TL as a modifier, only 1st trimester O3 was significantly associated with BWGA z-scores (coefficient: 0.33, 95% CI: 0.03, 0.63). In models considering TL interactions, a significant modifying effect was observed between 3rd trimester NO2 and BWGA z-scores (interaction p-value = 0.02). Specifically, a one interquartile range (1-IQR) increase in 3rd trimester NO2 was linked to a 0.28 (95% CI: 0.06, 0.52) change in BWGA z-score among shorter placental TL group, with no significant association among longer TL group. Among male infants, there were significant associations between 3rd trimester PM2.5 exposure and BWGA z-scores in the longer TL group (coefficient: -0.34, 95% CI: -0.61, -0.02), and between 1st trimester O3 exposure and BWGA z-scores among males in the shorter TL group (coefficient: 0.59, 95% CI: 0.06, 1.08). For females, only a negative association in 2nd trimester mixture model was observed within the longer TL group (coefficient: -0.10, 95% CI: -0.21, -0.01).

CONCLUSION

These findings highlight the need to consider the complex interactions among prenatal air pollutant exposures, placental TL, and fetal sex to better elucidate those at greatest risk for adverse birth outcomes.

Effect of a chimney-fitted improved stove on pregnancy outcomes in Northwest Ethiopia: a randomized controlled trial

BACKGROUND

Exposure to household air pollution during pregnancy has been linked to adverse pregnancy outcomes. Improved stove was implemented in Ethiopia to reduce this exposure and related health problems. However, the effects of improved stove interventions on pregnancy outcomes remains uncertain.

METHOD

Individually randomized stove replacement trial was conducted among 422 households in six low-income rural kebeles of Northwestern Ethiopia. Pregnant women without known health conditions were recruited at ≤ 24 weeks gestation and randomized to an intervention or control group with a 1:1 ratio. A baseline survey was collected and a balance test was done. Two-sided independent samples t-test for continuous outcomes and chi-square for categorical variables were used to compare the effect of the intervention between the groups. Mean differences with 95% CIs were calculated and a p-value of < 0.05 was considered statistically significant.

RESULT

In this study, the mean birth weight was 3065 g (SD = 453) among the intervention group and not statistically different from 2995 g (SD = 541) of control group. After adjusting for covariates, infants born from intervention group weighed 55 g more [95% CI: - 43 to 170) than infants born from the control group, but the difference was not statistically significant (P = 0.274). The respective percentages for low birth weight were 8% and 10.3% for intervention and control groups respectively (P = 0.346). However, the average gestational age at delivery was higher among improved stove users (38 weeks (SD = 8.2) compared to control groups 36.5 weeks (SD = 9.6) with statistically significant difference at 0.91 weeks (95% CI: 0.52 to 1.30 weeks, p < 0.001). The corresponding difference in risk ratio for preterm birth is 0.94 (95% CI:0.92 to 0.97; p < 0.001). The percentages for maternal complications, stillbirth, and miscarriage in the intervention group were not statistically different from the control group.

CONCLUSIONS

While the increase in average birth weight among babies born to mothers using improved stoves was not statistically significant, babies had a longer gestational age on average, offering valuable health benefits. However, the study didn't find a significant impact on other pregnancy outcomes like stillbirth, miscarriage, or maternal complications.

TRIAL REGISTRATION

The study was registered at the Pan African Clinical Trial Registry website under the code PACTR202111534227089, ( https://pactr.samrc.ac.za/ (Identifier). The first trial registration date was (11/11/2021).

Prenatal Exposure to Air Pollution and Respiratory Distress in Term Newborns: Results from the MIREC Prospective Pregnancy Cohort

BACKGROUND

Respiratory distress is the leading cause of neonatal morbidity and mortality worldwide, and prenatal exposure to air pollution is associated with adverse long-term respiratory outcomes; however, the impact of prenatal air pollution exposure on neonatal respiratory distress has not been well studied.

OBJECTIVES

We examined associations between prenatal exposures to fine particular matter (PM 2.5 ) and nitrogen dioxide (NO 2 ) with respiratory distress and related neonatal outcomes.

METHODS

We used data from the Maternal-Infant Research on Environmental Chemicals (MIREC) Study, a prospective pregnancy cohort (n = 2,001 ) recruited in the first trimester from 10 Canadian cities. Prenatal exposures to PM 2.5 (n = 1,321 ) and NO 2 (n = 1,064 ) were estimated using land-use regression and satellite-derived models coupled with ground-level monitoring and linked to participants based on residential location at birth. We calculated odds ratios (ORs) and 95% confidence intervals (CIs) for associations between air pollution and physician-diagnosed respiratory distress in term neonates in hierarchical logistic regression models adjusting for detailed maternal and infant covariates.

RESULTS

Approximately 7 % of newborns experienced respiratory distress. Neonates received clinical interventions including oxygen therapy (6%), assisted ventilation (2%), and systemic antibiotics (3%). Two percent received multiple interventions and 4% were admitted to the neonatal intensive care unit (NICU). Median PM 2.5 and NO 2 concentrations during pregnancy were 8.81   μ g / m 3 and 18.02  ppb , respectively. Prenatal exposures to air pollution were not associated with physician-diagnosed respiratory distress, oxygen therapy, or NICU admissions. However, PM 2.5 exposures were strongly associated with assisted ventilation (OR per 1 - μ g / m 3 increase in PM 2.5 = 1.17 ; 95% CI: 1.02, 1.35), multiple clinical interventions (OR per 1 - μ g / m 3 increase in PM 2.5 = 1.16 ; 95% CI: 1.07, 1.26), and systemic antibiotics, (OR per 1 - μ g / m 3 increase in PM 2.5 = 1.12 ; 95% CI: 1.04, 1.21). These associations were consistent across exposure periods-that is, during prepregnancy, individual trimesters, and total pregnancy-and robust to model specification. NO 2 exposure was associated with administration of systemic antibiotics (OR per 1-ppb increase in NO 2 = 1.03 ; 95% CI: 1.00, 1.06).

DISCUSSION

Prenatal exposures to PM 2.5 increased the risk of severe respiratory distress among term newborns. These findings support the development and prioritization of public health and prenatal care strategies to increase awareness and minimize prenatal exposures to air pollution. https://doi.org/10.1289/EHP12880.

Weekly prenatal PM2.5 and NO2 exposures in preterm, early term, and full term infants: Decrements in birth weight and critical windows of susceptibility

BACKGROUND

Previous studies have observed associations between birth weight and prenatal air pollution exposure, but there is not consensus on timing of critical windows of susceptibility.

OBJECTIVE

We estimated the difference in birth weight among preterm, early term and full term births associated with weekly exposure to PM2.5 and NO2 throughout gestation.

METHODS

We included all singleton live births in the Lower Peninsula of Michigan (United States) between 2007 and 2012 occurring at or after 32 weeks gestational age (n = 497,897). Weekly ambient PM2.5 and NO2 concentrations were estimated at maternal residences using 1-km gridded data from ensemble-based models. We utilized a distributed lag nonlinear model to estimate the difference in birth weight associated with weekly exposures from the last menstrual period (week 0) through 31 weeks gestation for preterm births; through 36 weeks gestation for early term births; and through 38 weeks gestation for full term births.

RESULTS

In single-pollutant models, a 5 μg/m3 increase in PM2.5 exposure was associated with a reduction in birth weight among preterm births (-37.1 g [95% confidence interval [CI]: 60.8 g, -13.5 g]); early term births (-13.5 g [95% CI: 26.2 g, -0.67 g]); and full term births (-8.23 g [95% CI: 15.8 g, -0.68 g])]. In single-pollutant models, a 10 ppb increase in NO2 exposure was associated with a -11.7 g (95% CI: 14.46 g, -8.92 g) decrement in birth weight among full term births only. In models co-adjusted for PM2.5 and NO2, PM2.5 exposure was associated with reduced birth weight among preterm births (-36.9 g [95% CI: 61.9 g, -11.8 g]) and NO2 exposure was associated with reduced birth weight among full term births (-11.8 g [95% CI: 14.7 g, -8.94 g]). The largest decrements in birth weight were associated with PM2.5 exposure between approximately 10 and 26 weeks of pregnancy; for NO2 exposure, the largest decrements in birth weight in full term births were associated with exposure between weeks 6-18.

CONCLUSION

We observed the largest and most persistent adverse associations between PM2.5 exposure and birth weight in preterm infants, and between NO2 exposure and birth weight in full term infants. Exposure during the first half of pregnancy had a greater impact on birthweight.

Development of Spatio-Temporal Land Use Regression Models for Fine Particulate Matter and Wood-Burning Tracers in Temuco, Chile

Biomass burning is common in much of the world, and in some areas, residential wood-burning has increased. However, air pollution resulting from biomass burning is an important public health problem. A sampling campaign was carried out between May 2017 and July 2018 in over 64 sites in four sessions, to develop a spatio-temporal land use regression (LUR) model for fine particulate matter (PM) and wood-burning tracers levoglucosan and soluble potassium (Ksol) in a city heavily impacted by wood-burning. The mean (sd) was 46.5 (37.4) μg m-3 for PM2.5, 0.607 (0.538) μg m-3 for levoglucosan, and 0.635 (0.489) μg m-3 for Ksol. LUR models for PM2.5, levoglucosan, and Ksol had a satisfactory performance (LOSOCV R2), explaining 88.8%, 87.4%, and 87.3% of the total variance, respectively. All models included sociodemographic predictors consistent with the pattern of use of wood-burning in homes. The models were applied to predict concentrations surfaces and to estimate exposures for an epidemiological study.

To promote healthy aging, focus on the environment

To build health equity for an aging world marked by dramatic disparities in healthy lifespan between countries, regions and population groups, research at the intersections of biology, toxicology and the social and behavioral sciences points the way: to promote healthy aging, focus on the environment. In this Perspective, we suggest that ideas and tools from the emerging field of geroscience offer opportunities to advance the environmental science of aging. Specifically, the capacity to measure the pace and progress of biological processes of aging within individuals from relatively young ages makes it possible to study how changing environments can change aging trajectories from early in life, in time to prevent or delay aging-related disease and disability and build aging health equity.

Health risk perceptions of household air pollution and perceived benefits of improved stoves among pregnant women in rural Ethiopia: a mixed method study

OBJECTIVE

Since community perceptions of the risk of biomass smoke and the benefits of improved stoves play a critical role in behaviour change to the uptake and sustainable utilisation of improved stoves, we aimed to assess the level of health risk perception on kitchen smoke and benefits of using improved stoves among pregnant women.

DESIGN

A community-based cross-sectional mixed method study.

SETTING

In six kebeles of a low-income rural community of South Gondar Zone, Northwestern Ethiopia.

PARTICIPANTS

All 455 households with pregnant women aged 18-38 years, in their first-trimester or second-trimester gestation, exclusively use traditional biomass-fuelled or locally modified mud stoves, and the primary cook in her household were included. But completed data were obtained only from 422 households.

RESULT

From 422 completed data, more than half, 63% (95% CI 58% to 68%) had high-level health risk perception of household air pollution, and nearly three-fourths, 74% (95% CI 70% to 79%) of the respondents perceived that using improved stove had benefits for their families. Participants in the 32-38 years age group, rich in asset index, presence of under-five children, being a member of any women group and large family size were positively associated with high-level health risk perception. Whereas respondents in the 18-24 years age group, presence of under-five children, husbands of primary or higher education, high health risk perception and not happy with the current stove were positively associated with perceived benefits of using an improved stove.

CONCLUSION

The observed level of health risk perception of biomass smoke and the benefits of using improved stoves may help to adopt effective intervention measures. This study also suggests that for successful intervention, clean cooking programmes and policies must consider many local factors influencing health risk perception and benefits of using improved stoves.

TRIAL REGISTRATION NUMBER

ACTR202111534227089.

Low-Cost Sensor Performance Intercomparison, Correction Factor Development, and 2+ Years of Ambient PM2.5 Monitoring in Accra, Ghana

Particulate matter air pollution is a leading cause of global mortality, particularly in Asia and Africa. Addressing the high and wide-ranging air pollution levels requires ambient monitoring, but many low- and middle-income countries (LMICs) remain scarcely monitored. To address these data gaps, recent studies have utilized low-cost sensors. These sensors have varied performance, and little literature exists about sensor intercomparison in Africa. By colocating 2 QuantAQ Modulair-PM, 2 PurpleAir PA-II SD, and 16 Clarity Node-S Generation II monitors with a reference-grade Teledyne monitor in Accra, Ghana, we present the first intercomparisons of different brands of low-cost sensors in Africa, demonstrating that each type of low-cost sensor PM2.5 is strongly correlated with reference PM2.5, but biased high for ambient mixture of sources found in Accra. When compared to a reference monitor, the QuantAQ Modulair-PM has the lowest mean absolute error at 3.04 μg/m3, followed by PurpleAir PA-II (4.54 μg/m3) and Clarity Node-S (13.68 μg/m3). We also compare the usage of 4 statistical or machine learning models (Multiple Linear Regression, Random Forest, Gaussian Mixture Regression, and XGBoost) to correct low-cost sensors data, and find that XGBoost performs the best in testing (R2: 0.97, 0.94, 0.96; mean absolute error: 0.56, 0.80, and 0.68 μg/m3 for PurpleAir PA-II, Clarity Node-S, and Modulair-PM, respectively), but tree-based models do not perform well when correcting data outside the range of the colocation training. Therefore, we used Gaussian Mixture Regression to correct data from the network of 17 Clarity Node-S monitors deployed around Accra, Ghana, from 2018 to 2021. We find that the network daily average PM2.5 concentration in Accra is 23.4 μg/m3, which is 1.6 times the World Health Organization Daily PM2.5 guideline of 15 μg/m3. While this level is lower than those seen in some larger African cities (such as Kinshasa, Democratic Republic of the Congo), mitigation strategies should be developed soon to prevent further impairment to air quality as Accra, and Ghana as a whole, rapidly grow.

Structural racism, air pollution and the association with adverse birth outcomes in the United States: the value of examining intergenerational associations

Structurally racist policies and practices of the past are likely to be a driving factor in current day differences in exposure to air pollution and may contribute to observed racial and ethnic disparities in adverse birth outcomes in the United States (U.S.). Non-Hispanic Black women in the U.S. experience poorer health outcomes during pregnancy and throughout the life course compared to non-Hispanic White women. This disparity holds even among non-Hispanic Black women with higher socioeconomic status. Reasons for this finding remain unclear, but long-term environmental exposure, either historical exposure or both historical and ongoing exposure, may contribute. Structural racism likely contributes to differences in social and environmental exposures by race in the U.S. context, and these differences can affect health and wellbeing across multiple generations. In this paper, we briefly review current knowledge and recommendations on the study of race and structural racism in environmental epidemiology, specifically focused on air pollution. We describe a conceptual framework and opportunities to use existing historical data from multiple sources to evaluate multi-generational influences of air pollution and structurally racist policies on birth and other relevant health outcomes. Increased analysis of this kind of data is critical for our understanding of structural racism's impact on multiple factors, including environmental exposures and adverse health outcomes, and identifying how past policies can have enduring legacies in shaping health and well-being in the present day. The intended purpose of this manuscript is to provide an overview of the widespread reach of structural racism, its potential association with health disparities and a comprehensive approach in environmental health research that may be required to study and address these problems in the U.S. The collaborative and methodological approaches we highlight have the potential to identify modifiable factors that can lead to effective interventions for health equity.

Individual, Independent, and Joint Associations of Toxic Metals and Manganese on Hypertensive Disorders of Pregnancy: Results from the MIREC Canadian Pregnancy Cohort

BACKGROUND

Toxic metals, such as lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg), may be associated with a higher risk of gestational hypertension and preeclampsia, whereas manganese (Mn) is an essential metal that may be protective.

OBJECTIVES

We estimated the individual, independent, and joint associations of Pb, Cd, As, Hg, and Mn on the risk of developing gestational hypertension and preeclampsia in a cohort of Canadian women.

METHODS

Metal concentrations were analyzed in first and third trimester maternal blood (n = 1,560 ). We measured blood pressure after 20 wk gestation to diagnose gestational hypertension, whereas proteinuria and other complications defined preeclampsia. We estimated individual and independent (adjusted for coexposure) relative risks (RRs) for each doubling of metal concentrations and examined interactions between toxic metals and Mn. We used quantile g-computation to estimate the joint effect of trimester-specific exposures.

RESULTS

Each doubling of third trimester Pb (RR = 1.54 ; 95% CI: 1.06, 2.22) and first trimester blood As (RR = 1.25 ; 95% CI: 1.01, 1.58) was independently associated with a higher risk of developing preeclampsia. First trimester blood As (RR = 3.40 ; 95% CI: 1.40, 8.28) and Mn (RR = 0.63 ; 95% CI: 0.42, 0.94) concentrations were associated with a higher and lower risk, respectively, of developing gestational hypertension. Mn modified the association with As such that the deleterious association with As was stronger at lower concentrations of Mn. First trimester urinary dimethylarsinic acid concentrations were not associated with gestational hypertension (RR = 1.31 ; 95% CI: 0.60, 2.85) or preeclampsia (RR = 0.92 ; 95% CI: 0.68, 1.24). We did not observe overall joint effects for blood metals.

DISCUSSION

Our results confirm that even low blood Pb concentrations are a risk factor for preeclampsia. Women with higher blood As concentrations combined with lower Mn in early pregnancy were more likely to develop gestational hypertension. These pregnancy complications impact maternal and neonatal health. Understanding the contribution of toxic metals and Mn is of public health importance. https://doi.org/10.1289/EHP10825.

Can Maternal Exposure to Air Pollution Affect Post-Natal Liver Development?

Emerging evidence suggests that inhalation of particulate matter (PM) can have direct adverse effects on liver function. Early life is a time of particular vulnerability to the effects of air pollution. On that basis, we tested whether in utero exposure to residential PM has an impact on the developing liver. Pregnant mice (C57BL/6J) were intranasally administered 100 µg of PM sampled from residential roof spaces (~5 mg/kg) on gestational days 13.5, 15.5, and 17.5. The pups were euthanized at two weeks of age, and liver tissue was collected to analyse hepatic metabolism (glycogen storage and lipid level), cellular responses (oxidative stress, inflammation, and fibrosis), and genotoxicity using a range of biochemical assays, histological staining, ELISA, and qPCR. We did not observe pronounced effects of environmentally sampled PM on the developing liver when examining hepatic metabolism and cellular response. However, we did find evidence of liver genomic DNA damage in response to in utero exposure to PM. This effect varied depending on the PM sample. These data suggest that in utero exposure to real-world PM during mid-late pregnancy has limited impacts on post-natal liver development.

Association between air pollutants and neural tube defects during pregnancy in Lanzhou, China: a time series analysis

Few studies have evaluated the association between air pollutants and neural tube defects (NTDs). Moreover, the existing research ignores the lag effect of air pollution on health and provides inconsistent epidemiological evidence. We aim to estimate the association between air pollution and NTDs during the first trimester of pregnancy and identify specific susceptible windows. Birth data was collected from the Birth Defects Surveillance Network in Lanzhou from September 1, 2014, to December 31, 2019. Air quality and meteorological data were collected from ambient air monitoring stations and China Meteorological Data Network. The log connection function of the Poisson distribution function is used to establish a DLNM model to estimate the exposure-effect relationship and exposure-lag relationship association between air pollutants levels and NTDs. There were 320,787 perinatal infants in Lanzhou from September 1, 2014, to December 31, 2019, and 486 cases of NTDs (1.5‰). The result indicates that exposure to inhalable particles (PM₁₀) at lag 2-4 weeks was significantly associated with the risk of NTDs, with the most significant impact at the lag 2 week (RR=1.048, 95%CI, 1.015-1.084). Exposure to fine particulate matter (PM_2.5) at the lag 2 week was significantly associated with the risk of NTDs, with the most significant impact at the lag 2 week (RR=1.077, 95%CI, 1.004-1.155). Exposure to sulfur dioxide (SO₂) and nitrogen dioxide (NO₂) at lag 3-6weeks was significantly associated with the risk of NTDs, with the most significant impact at the lag 4 week (RR=1.220, 95%CI, 1.105-1.348; RR=1.143, 95%CI, 1.048-1.245). This study provides further evidence that exposure to air pollutants in the first trimester of pregnancy significantly increases the risk of neural tube defects.

The association between ambient particulate matter exposure and the telomere-mitochondrial axis of aging in newborns

BACKGROUND

Particulate matter (PM) is associated with aging markers at birth, including telomeres and mitochondria. It is unclear whether markers of the core-axis of aging, i.e. tumor suppressor p53 (p53) and peroxisome proliferator-activated receptor gamma co-activator 1 alpha (PGC-1α), are associated with prenatal air pollution and whether there are underlying mechanisms.

METHODS

556 mother-newborn pairs from the ENVIRONAGE birth cohort were recruited at the East Limburg Hospital in Genk (Belgium). In placenta and cord blood, telomere length (TL) and mitochondrial DNA content (mtDNAc) were measured using quantitative real-time polymerase chain reaction (qPCR). In cord plasma, p53 and PGC-1α protein levels were measured using ELISA. Daily ambient PM_2.5 concentrations during gestation were calculated using a spatial temporal interpolation model. Distributed lag models (DLMs) were applied to assess the association between prenatal PM_2.5 exposure and each molecular marker. Mediation analysis was performed to test for underlying mechanisms.

RESULTS

A 5 µg/m³ increment in PM_2.5 exposure was associated with -11.23 % (95 % CI: -17.36 % to -4.65 %, p = 0.0012) and -7.34 % (95 % CI: -11.56 % to -2.92 %, p = 0.0014) lower placental TL during the entire pregnancy and second trimester respectively, and with -12.96 % (95 % CI: -18.84 % to -6.64 %, p < 0.001) lower placental mtDNAc during the third trimester. Furthermore, PM_2.5 exposure was associated with a 12.42 % (95 % CI: -1.07 % to 27.74 %, p = 0.059) higher cord plasma p53 protein level and a -3.69 % (95 % CI: -6.97 % to -0.31 %, p = 0.033) lower cord plasma PGC-1α protein level during the third trimester. Placental TL mediated 65 % of the negative and 17 % of the positive association between PM_2.5 and placental mtDNAc and cord plasma p53 protein levels, respectively.

CONCLUSION

Ambient PM_2.5 exposure during pregnancy is associated with markers of the core-axis of aging, with TL as a mediating factor. This study strengthens the hypothesis of the air pollution induced core-axis of aging, and may unravel a possible underlying mediating mechanism in an early-life epidemiological context.

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

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