Prenatal particulate air pollution exposure and body composition in urban preschool children: Examining sensitive windows and sex-specific associations

Developmental programming of obesity by maternal exposure to concentrated ambient PM2.5 is maternally transmitted into the third generation in a mouse model

BACKGROUND

Obesity is an uncontrolled global epidemic and one of the leading global public health challenges. Maternal exposure to ambient fine particulate matter (PM2.5) may adversely program offspring's adiposity, suggesting a specialized role of PM2.5 pollution in the global obesity epidemic. However, the vulnerable window for this adverse programming and how it is cross-generationally transmitted have not been determined. Therefore, in the present study, female C57Bl/6 J mice were exposed to filtered air (FA) or concentrated ambient PM2.5 (CAP) during different periods, and the development and adulthood adiposity of their four-generational offspring were assessed.

RESULTS

Our data show that the pre-conceptional but not gestational exposure to CAP was sufficient to cause male but not female offspring's low birth weight, accelerated postnatal weight gain, and increased adulthood adiposity. These adverse developmental traits were transmitted into the F2 offspring born by the female but not male F1 offspring of CAP-exposed dams. In contrast, no adverse development was noted in the F3 offspring.

CONCLUSIONS

The present study identified a pre-conceptional window for the adverse programming of adiposity by maternal exposure to PM2.5, and showed that it was maternally transmitted into the third generation. These data not only call special attention to the protection of women from exposure to PM2.5, but also may facilitate the development of intervention to prevent this adverse programming.

Statistical Approaches for Investigating Periods of Susceptibility in Children's Environmental Health Research

PURPOSE OF REVIEW

Children's environmental health researchers are increasingly interested in identifying time intervals during which individuals are most susceptible to adverse impacts of environmental exposures. We review recent advances in methods for assessing susceptible periods.

RECENT FINDINGS

We identified three general classes of modeling approaches aimed at identifying susceptible periods in children's environmental health research: multiple informant models, distributed lag models, and Bayesian approaches. Benefits over traditional regression modeling include the ability to formally test period effect differences, to incorporate highly time-resolved exposure data, or to address correlation among exposure periods or exposure mixtures. Several statistical approaches exist for investigating periods of susceptibility. Assessment of susceptible periods would be advanced by additional basic biological research, further development of statistical methods to assess susceptibility to complex exposure mixtures, validation studies evaluating model assumptions, replication studies in different populations, and consideration of susceptible periods from before conception to disease onset.

Association between prenatal particulate air pollution exposure and telomere length in cord blood: Effect modification by fetal sex

INTRODUCTION

In utero particulate matter exposure produces oxidative stress that impacts cellular processes that include telomere biology. Newborn telomere length is likely critical to an individual's telomere biology; reduction in this initial telomere setting may signal increased susceptibility to adverse outcomes later in life. We examined associations between prenatal particulate matter with diameter ≤2.5 µm (PM_2.5) and relative leukocyte telomere length (LTL) measured in cord blood using a data-driven approach to characterize sensitive windows of prenatal PM_2.5 effects and explore sex differences.

METHODS

Women who were residents of Mexico City and affiliated with the Mexican Social Security System were recruited during pregnancy (n = 423 for analyses). Mothers' prenatal exposure to PM_2.5 was estimated based on residence during pregnancy using a validated satellite-based spatio-temporally resolved prediction model. Leukocyte DNA was extracted from cord blood obtained at delivery. Duplex quantitative polymerase chain reaction was used to compare the relative amplification of the telomere repeat copy number to single gene (albumin) copy number. A distributed lag model incorporating weekly averages for PM_2.5 over gestation was used in order to explore sensitive windows. Sex-specific associations were examined using Bayesian distributed lag interaction models.

RESULTS

In models that included child's sex, mother's age at delivery, prenatal environmental tobacco smoke exposure, pre-pregnancy BMI, gestational age, birth season and assay batch, we found significant associations between higher PM_2.5 exposure during early pregnancy (4-9 weeks) and shorter LTL in cord blood. We also identified two more windows at 14-19 and 34-36 weeks in which increased PM_2.5 exposure was associated with longer LTL. In stratified analyses, the mean and cumulative associations between PM_2.5 and shortened LTL were stronger in girls when compared to boys.

CONCLUSIONS

Increased PM_2.5 during specific prenatal windows was associated with shorter LTL and longer LTL. PM_2.5 was more strongly associated with shortened LTL in girls when compared to boys. Understanding sex and temporal differences in response to air pollution may provide unique insight into mechanisms.

Prenatal exposure to ambient fine particulate matter induces dysregulations of lipid metabolism in adipose tissue in male offspring

Prenatal exposure to ambient fine particles (diameter < 0.25 μm, PM_2.5) has been found to be associated with abnormal growth and development in offspring. However, the effects of PM_2.5 on the lipid metabolism of adipose tissue in offspring are unclear. In the present study, we established a mouse model of prenatal exposure to PM_2.5 by intratracheal instillation to pregnant C57BL/6 female mice with PM_2.5 suspension or normal saline. We found that prenatal exposure to PM_2.5 of a mouse model reduced body weight in adult male offspring after 6 weeks old. Histological analysis showed that the adipocyte size was significantly reduced in epididymal adipose tissue (eWAT) in male offspring, but not in brown adipose tissue. The expression levels of genes related to fatty acid synthesis (ACC1, ACSL1) and oxidation (PPARα) in eWAT were also significantly decreased. In addition, downregulation of pro-inflammatory cytokines (TNFα, IL-1β, IL-6) was also observed. Lipidomics analysis of eWAT demonstrated that prenatal exposure of PM_2.5 reduced lysophosphatidylcholines (LPC), phosphatidylcholines (PC), phosphatidylethanolamines (PE), sphingomyelins (SM), and ceramides (Cer), indicating that metabolic pathways, including SM-Cer signaling and glycerophospholipids remodeling, were disrupted. In summary, prenatal exposure to PM_2.5 was associated with the dysregulations in lipid metabolism of eWAT and pro-inflammatory response in male offspring.

The association of early-life exposure to air pollution with lung function at ~17.5 years in the "Children of 1997" Hong Kong Chinese Birth Cohort

BACKGROUND

Early-life air pollution exposure is associated with lung function in children and adolescents. However, whether the association of prenatal and early postnatal exposure to air pollution with lung function continues into adulthood remains unclear.

OBJECTIVE

To investigate the associations of early exposure to air pollution with lung function at ~17.5 years in a non-western developed setting with more concentrated air pollutants.

METHODS

We examined the associations of exposure to particular matter with an aerodynamic diameter of <10 μm (PM₁₀), nitrogen dioxides (NO₂), nitric oxide (NO), sulfur dioxide (SO₂) in standard deviations (SD)) at different early life stages with lung function (indicated by forced vital capacity (FVC), forced expiratory volume in 1 s (FEV₁) and forced expiratory flow at 25%-75% of the pulmonary volume (FEF_25%-75%)) in SD at ~17.5 years, personal history of wheezing and asthma in the population-representative Hong Kong Chinese birth cohort "Children of 1997"(n = 2942).

RESULTS

Higher in utero and infancy and toddlerhood NO₂ were associated with lower FEV₁ (-0.022, 95% confidence interval (CI) -0.029 to -0.015 and - 0.026, 95% CI -0.033 to -0.019), FEV₁/FVC (-0.035, 95% CI -0.050 to -0.021 and -0.052, 95% CI -0.066 to -0.038) and FEF_25%-75% (-0.031, 95% CI -0.040 to -0.022 and -0.043, 95% CI -0.051 to -0.035). A similar association was observed for NO. Weak associations of NO₂ and NO with FVC were observed (-0.011, 95% CI -0.018 to -0.003 and -0.010, 95% CI -0.020 to -0.001). NO_x was associated with higher risk of wheezing (1.08, 95% CI 1.03 to 1.14) but not asthma (1.02, 95% CI 0.94 to 1.11). SO₂ and PM₁₀ were not clearly associated with lung function, wheezing or asthma.

CONCLUSION

Our findings suggest that early exposure to air pollution from NO₂ may have long-term effects on lung function, which could affect respiratory health throughout life.

Developmental Origins of Disease: Emerging Prenatal Risk Factors and Future Disease Risk

Purpose of review

Many of the diseases and dysfunctions described in the paradigm of the developmental origins of health and disease have been studied in relation to prenatal nutrition or environmental toxicant exposures. Here, we selectively review the current research on four exposures-two nutritional and two environmental-that have recently emerged as prenatal risk factors for long-term health outcomes.

Recent findings

Recent studies have provided strong evidence that prenatal exposure to (1) excessive intake of sugar-sweetened beverages, (2) unhealthy dietary patterns, (3) perfluoroalkyl substances, and (4) fine particulate matter, may increase risk of adverse health outcomes, such as obesity, cardiometabolic dysfunction, and allergy/asthma.

Summary

Emerging prenatal nutritional factors and environmental toxicants influence offspring long-term health. More work is needed to identify the role of paternal exposures and maternal exposures during the preconception period and to further elucidate causality through intervention studies. The ubiquity of these emerging nutritional and environmental exposures makes this area of inquiry of considerable public health importance.

Ambient Air Pollution and Asthma-Related Outcomes in Children of Color of the USA: a Scoping Review of Literature Published Between 2013 and 2017

PURPOSE OF REVIEW

Given racial disparities in ambient air pollution (AAP) exposure and asthma risk, this review offers an overview of the literature investigating the ambient air pollution-asthma relationship in children of color between 2013 and 2017.

RECENT FINDINGS

AAP is likely a key contributor to the excess burden of asthma in children of color due to pervasive exposure before birth, at home, and in school. Recent findings suggest that psychosocial stressors may modify the relationship between AAP and asthma. The effect of AAP on asthma in children of color is likely modulated by multiple unique psychosocial stressors and gene-environment interactions. Although children of color are being included in asthma studies, more research is still needed on impacts of specific criteria pollutants throughout the life course. Additionally, future studies should consider historical factors when analyzing current exposure profiles.

Prenatal Exposure to Traffic Pollution and Childhood Body Mass Index Trajectory

Background: Limited evidence suggests an association between prenatal exposure to traffic pollution and greater adiposity in childhood, but the time window during which growth may be most affected is not known. Methods: We studied 1,649 children in Project Viva, a Boston-area pre-birth cohort. We used spatiotemporal models to estimate prenatal residential air pollution exposures and geographic information systems to estimate neighborhood traffic density and roadway proximity. We used weight and stature measurements at clinical and research visits to estimate a BMI trajectory for each child with mixed-effects natural cubic spline models. In primary analyses, we examined associations of residential PM_2.5 and black carbon (BC) exposures during the third trimester and neighborhood traffic density and home roadway proximity at birth address with (1) estimated BMI at 6 month intervals through 10 years of age, (2) magnitude and timing of BMI peak and rebound, and (3) overall BMI trajectory. In secondary analyses, we examined associations of residential PM_2.5 and BC exposures during the first and second trimesters with BMI outcomes. Results: Median (interquartile range; IQR) concentration of residential air pollution during the third trimester was 11.4 (1.7) μg/m³ for PM_2.5 and 0.7 (0.3) μg/m³ for BC. Participants had a median (IQR) of 13 (7) clinical or research BMI measures from 0 to 10 years of age. None of the traffic pollution exposures were significantly associated with any of the BMI outcomes in covariate-adjusted models, although effect estimates were in the hypothesized direction for neighborhood traffic density and home roadway proximity. For example, greater neighborhood traffic density [median (IQR) 857 (1,452) vehicles/day x km of road within 100 m of residential address at delivery] was associated with a higher BMI throughout childhood, with the strongest associations in early childhood [e.g., per IQR increment natural log-transformed neighborhood traffic density, BMI at 12 months of age was 0.05 (-0.03, 0.13) kg/m² higher and infancy peak BMI was 0.05 (-0.03, 0.14) kg/m² higher]. Conclusions: We found no evidence for a persistent effect of prenatal exposure to traffic pollution on BMI trajectory from birth through mid-childhood in a population exposed to modest levels of air pollution.