Sensitive development windows of prenatal air pollution and cognitive functioning in preschool age Mexican children

Introduction

Neurotoxicity resulting from air pollution is of increasing concern. Considering exposure timing effects on neurodevelopmental impairments may be as important as the exposure dose. We used distributed lag regression to determine the sensitive windows of prenatal exposure to fine particulate matter (PM2.5) on children's cognition in a birth cohort in Mexico.

Methods

Analysis included 553 full-term (≥37 weeks gestation) children. Prenatal daily PM2.5 exposure was estimated using a validated satellite-based spatiotemporal model. McCarthy Scales of Children's Abilities (MSCA) were used to assess children's cognitive function at 4-5 years old (lower scores indicate poorer performance). To identify susceptibility windows, we used Bayesian distributed lag interaction models to examine associations between prenatal PM2.5 levels and MSCA. This allowed us to estimate vulnerable windows while testing for effect modification.

Results

After adjusting for maternal age, socioeconomic status, child age, and sex, Bayesian distributed lag interaction models showed significant associations between increased PM2.5 levels and decreased general cognitive index scores at 31-35 gestation weeks, decreased quantitative scale scores at 30-36 weeks, decreased motor scale scores at 30-36 weeks, and decreased verbal scale scores at 37-38 weeks. Estimated cumulative effects (CE) of PM2.5 across pregnancy showed significant associations with general cognitive index (C E ^ = -0.35, 95% confidence interval [CI] = -0.68, -0.01), quantitative scale (C E ^ = -0.27, 95% CI = -0.74, -0.02), motor scale (C E ^ = -0.25, 95% CI = -0.44, -0.05), and verbal scale (C E ^ = -0.2, 95% CI = -0.43, -0.02). No significant sex interactions were observed.

Conclusions

Prenatal exposure to PM2.5, particularly late pregnancy, was inversely associated with subscales of MSCA. Using data-driven methods to identify sensitive window may provide insight into the mechanisms of neurodevelopmental impairment due to pollution.

Preconceptional and prenatal exposure to air pollutants and risk of gestational diabetes in the MADRES prospective pregnancy cohort study

Background

Air pollution has been associated with gestational diabetes mellitus (GDM). We aim to investigate susceptible windows of air pollution exposure and factors determining population vulnerability.

Methods

We ascertained GDM status in the prospective Maternal and Developmental Risks from Environmental and Social Stressors (MADRES) pregnancy cohort from Los Angeles, California, USA. We calculated the relative risk of GDM by exposure to ambient particulate matter (PM10; PM2.5), nitrogen dioxide (NO2), and ozone (O3) in each week from 12 weeks before to 24 weeks after conception, adjusting for potential confounders, with distributed lag models to identify susceptible exposure windows. We examined effect modification by prenatal depression, median-split pre-pregnancy BMI (ppBMI) and age.

Findings

Sixty (9.7%) participants were diagnosed with GDM among 617 participants (mean age: 28.2 years, SD: 5.9; 78.6% Hispanic, 11.8% non-Hispanic Black). GDM risk increased with exposure to PM2.5, PM10, and NO2 in a periconceptional window ranging from 5 weeks before to 5 weeks after conception: interquartile-range increases in PM2.5, PM10, and NO2 during this window were associated with increased GDM risk by 5.7% (95% CI: 4.6-6.8), 8.9% (8.1-9.6), and 15.0% (13.9-16.2), respectively. These sensitive windows generally widened, with greater effects, among those with prenatal depression, with age ≥28 years, or with ppBMI ≥27.5 kg/m2, than their counterparts.

Interpretation

Preconception and early-pregnancy are susceptible windows of air pollutants exposure that increased GDM risk. Prenatal depression, higher age, or higher ppBMI may increase one's vulnerability to air pollution-associated GDM risk.

Funding

National Institutes of Health, Environmental Protection Agency.

Maternal and Childhood Ambient Air Pollution Exposure and Mental Health Symptoms and Psychomotor Development in Children: An Australian Population-Based Longitudinal Study

BACKGROUND

Accumulating evidence indicates early life exposure to air pollution, a suspected neurotoxicant, is negatively associated with children's neurodevelopment.

OBJECTIVES

To explore the role of multiple exposure periods to ambient particulate matter with diameter <2.5 μm (PM_2.5) and nitrogen dioxide (NO₂) on emotion and behaviour, and early development in children <13 years.

METHODS

We used data from Mothers and their Children's Health (MatCH) study, a 2016/17 sub-study from a prospective longitudinal study, the Australian Longitudinal Study on Women's Health. Annual PM_2.5 and NO₂ estimates since 1996 were obtained from a land-use regression model. Maternal residential proximity to roadways were used as a proxy measure of exposure to traffic-related air pollution. Child outcomes were maternal-rated emotional and behavioural problems (Strengths and Difficulties Questionnaire; SDQ, aged 2-12 years, n = 5471 children) and developmental delay in communication and gross motor skills (Ages and Stages Questionnaire; ASQ, aged 1-66 months, n = 1265 children). Defined exposure periods were early life exposure ('during pregnancy' and 'first year of life') and 'children's lifetime exposure'. Ambient air pollution was divided into tertiles and logistic regression was performed to estimate odds ratio (OR) for each child outcome, adjusting for potential confounders.

RESULTS

Children exposed to moderate and high PM_2.5 exposure, compared to low exposure, across all periods, had higher odds of emotional and behavioural problems, and gross motor delay. Children's lifetime exposure to moderate levels of PM_2.5 (5.9-7.1 µg/m³) was associated with 1.27 (95% confidence interval 1.03, 1.57) fold higher odds of emotional/behavioural problems. Similar associations were found for moderate PM_2.5 levels at 'first year of life' in a two-pollutant model only (OR: 1.30; 1.05, 1.60). However, there was insufficient evidence to suggest that NO₂ exposure or living within 200 m of major roads was associated with emotional and behaviour problems or developmental delay across any exposure periods.

CONCLUSION

We found isolated evidence that early life and childhood exposure to PM_2.5 may be associated with emotional and behavioural problems and delays in gross motor skills, but most associations were null. Due to the limited number of longitudinal studies on low-exposure settings, further studies with more temporally refined exposure assessment are warranted.

Endocrine Disruption: Current approaches for regulatory testing and assessment of plant protection products are fit for purpose

The ongoing debate concerning the regulation of endocrine disruptors, has increasingly led to questions concerning the current testing of chemicals and whether this is adequate for the assessment of potential endocrine disrupting effects. This paper describes the current testing approaches for plant protection product (PPP) active substances in the European Union and the United States and how they relate to the assessment of endocrine disrupting properties for human and environmental health. This includes a discussion of whether the current testing approaches cover modalities other than the estrogen, androgen, thyroid and steroidogenesis (EATS) pathways, sensitive windows of exposure, adequate assessment of human endocrine disorders and wildlife species, and the determination of thresholds for endocrine disruption. It is concluded, that the scope and nature of the core and triggered data requirements for PPP active substances are scientifically robust to address adverse effects mediated through endocrine mode(s) of action and to characterise these effects in terms of dose response.

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

BACKGROUND

Evolving animal studies and limited epidemiological data show that prenatal air pollution exposure is associated with childhood obesity. Timing of exposure and child sex may play an important role in these associations. We applied an innovative method to examine sex-specific sensitive prenatal windows of exposure to PM_2.5 on anthropometric measures in preschool-aged children.

METHODS

Analyses included 239 children born ≥ 37 weeks gestation in an ethnically-mixed lower-income urban birth cohort. Prenatal daily PM_2.5 exposure was estimated using a validated satellite-based spatio-temporal model. Body mass index z-score (BMI-z), fat mass, % body fat, subscapular and triceps skinfold thickness, waist and hip circumferences and waist-to-hip ratio (WHR) were assessed at age 4.0 ± 0.7 years. Using Bayesian distributed lag interaction models (BDLIMs), we examined sex differences in sensitive windows of weekly averaged PM_2.5 levels on these measures, adjusting for child age, maternal age, education, race/ethnicity, and pre-pregnancy BMI.

RESULTS

Mothers were primarily Hispanic (55%) or Black (26%), had ≤ 12 years of education (66%) and never smoked (80%). Increased PM_2.5 exposure 8-17 and 15-22 weeks gestation was significantly associated with increased BMI z-scores and fat mass in boys, but not in girls. Higher PM_2.5 exposure 10-29 weeks gestation was significantly associated with increased WHR in girls, but not in boys. Prenatal PM_2.5 was not significantly associated with other measures of body composition. Estimated cumulative effects across pregnancy, accounting for sensitive windows and within-window effects, were 0.21 (95%CI = 0.01-0.37) for BMI-z and 0.36 (95%CI = 0.12-0.68) for fat mass (kg) in boys, and 0.02 (95%CI = 0.01-0.03) for WHR in girls, all per µg/m³ increase in PM_2.5.

CONCLUSIONS

Increased prenatal PM_2.5 exposure was more strongly associated with indices of increased whole body size in boys and with an indicator of body shape in girls. Methods to better characterize vulnerable windows may provide insight into underlying mechanisms contributing to sex-specific associations.

Prenatal particulate air pollution and neurodevelopment in urban children: Examining sensitive windows and sex-specific associations

BACKGROUND

Brain growth and structural organization occurs in stages beginning prenatally. Toxicants may impact neurodevelopment differently dependent upon exposure timing and fetal sex.

OBJECTIVES

We implemented innovative methodology to identify sensitive windows for the associations between prenatal particulate matter with diameter ≤ 2.5 μm (PM2.5) and children's neurodevelopment.

METHODS

We assessed 267 full-term urban children's prenatal daily PM2.5 exposure using a validated satellite-based spatio-temporally resolved prediction model. Outcomes included IQ (WISC-IV), attention (omission errors [OEs], commission errors [CEs], hit reaction time [HRT], and HRT standard error [HRT-SE] on the Conners' CPT-II), and memory (general memory [GM] index and its components - verbal [VEM] and visual [VIM] memory, and attention-concentration [AC] indices on the WRAML-2) assessed at age 6.5±0.98 years. To identify the role of exposure timing, we used distributed lag models to examine associations between weekly prenatal PM2.5 exposure and neurodevelopment. Sex-specific associations were also examined.

RESULTS

Mothers were primarily minorities (60% Hispanic, 25% black); 69% had ≤12 years of education. Adjusting for maternal age, education, race, and smoking, we found associations between higher PM2.5 levels at 31-38 weeks with lower IQ, at 20-26 weeks gestation with increased OEs, at 32-36 weeks with slower HRT, and at 22-40 weeks with increased HRT-SE among boys, while significant associations were found in memory domains in girls (higher PM2.5 exposure at 18-26 weeks with reduced VIM, at 12-20 weeks with reduced GM).

CONCLUSIONS

Increased PM2.5 exposure in specific prenatal windows may be associated with poorer function across memory and attention domains with variable associations based on sex. Refined determination of time window- and sex-specific associations may enhance insight into underlying mechanisms and identification of vulnerable subgroups.