Association between telomere length and neuropsychological function at 4-5 years in children from the INMA project: a cross-sectional study

Shortened telomere length (TL) has been associated with lower cognitive performance, different neurological diseases in adults, and certain neurodevelopmental disorders in children. However, the evidence about the association between TL and neuropsychological developmental outcomes in children from the general population is scarce. Therefore, this study aimed to explore the association between TL and neuropsychological function in children 4-5 years of age. We included 686 children from the INMA Project, a population-based birth cohort in Spain. Leucocyte TL was determined by quantitative PCR method, and neuropsychological outcomes were measured using the McCarthy Scales of Children's Abilities (MCSA). Multiple linear regression models were used to estimate associations adjusted for potential confounding variables. Main findings showed that a longer TL was associated with a higher mean working memory score (β = 4.55; 95% CI = 0.39, 8.71). In addition, longer TL was associated with a higher mean global quantitative score (β = 3.85; 95% CI = -0.19, 7.89), although the association was marginally significant. To our knowledge, this is the first study that shows a positive association between TL and better neuropsychological outcomes in children. Although further research is required to confirm these results, this study supports the hypothesis that TL is essential in protecting and maintaining a child's health, including cognitive functions such as working memory.

Physical activity and body mass related to catch-up lung function growth in childhood: a population-based accelerated cohort study

OBJECTIVE

The existence of catch-up lung function growth and its predictors is uncertain. We aimed to identify lung function trajectories and their predictors in a population-based birth cohort.

METHODS

We applied group-based trajectory modelling to z-scores of forced expiratory volume in 1 second (zFEV1) and z-scores of forced vital capacity (zFVC) from 1151 children assessed at around 4, 7, 9, 10, 11, 14 and 18 years. Multinomial logistic regression models were used to test whether potential prenatal and postnatal predictors were associated with lung function trajectories.

RESULTS

We identified four lung function trajectories: a low (19% and 19% of the sample for zFEV1 and zFVC, respectively), normal (62% and 63%), and high trajectory (16% and 13%) running in parallel, and a catch-up trajectory (2% and 5%) with catch-up occurring between 4 and 10 years. Fewer child allergic diseases and higher body mass index z-score (zBMI) at 4 years were associated with the high and normal compared with the low trajectories, both for zFEV1 and zFVC. Increased children's physical activity during early childhood and higher zBMI at 4 years were associated with the catch-up compared with the low zFEV1 trajectory (relative risk ratios: 1.59 per physical activity category (1.03-2.46) and 1.47 per zBMI (0.97-2.23), respectively). No predictors were identified for zFVC catch-up growth.

CONCLUSION

We found three parallel-running and one catch-up zFEV1 and zFVC trajectories, and identified physical activity and body mass at 4 years as predictors of zFEV1 but not zFVC catch-up growth.

Exploring the Association between Parental Employment Status, Education Level, and Sensory Reactivity in Spanish Children Aged 3-7 Years: Findings from the InProS Study

This study explored the association between parental employment status and education level and the prevalence of sensory reactivity (SR) in population-based sample of school-aged children. SR was assessed in 495 children using the parent-reported Short Sensory Profile (SSP) questionnaire. Children with SR were identified based on probable or definitive differences in total SSP and subscales. Association between parental employment and education level were explored using multiple Poisson regression models with robust variance, adjusted for potential confounders. The main findings showed that a mother's unemployment status was associated with higher prevalence of SR for the taste/smell sensitivity subscale (PR = 1.66, 95%CI: 1.08-2.56), and the low energy/weak (PR = 2.18, 95%CI: 1.31-3.49) subscale. A lower education level of a father was also associated with a higher prevalence of sensory problems on the tactile sensitivity subscale (PRprimary education = 2.68, 95%CI: 1.27-5.61; PRsecondary education = 1.96, 95%CI: 1.004-3.66) and the low energy/weak subscale (PRsecondary education = 1.95, 95%CI: 1.02-3.73). This study underscores the impact of parental employment and education on SR in school-aged children, offering insights for interventions and support systems aimed at improving their sensory functioning and overall well-being.

Urban environment exposures, energy balance-related behaviors and their combination in preschoolers from three European countries

BACKGROUND

Urban environments are characterized by many factors that may influence children's energy balance-related behaviors (EBRBs), but there is limited research on the impact of prospective exposure to multiple urban factors in preschoolers. We evaluated prospective associations between various urban exposures and EBRBs in preschoolers across Europe, with EBRBs considered both individually and combined into lifestyle patterns.

METHODS

We used data from 4,073 preschoolers (aged 3-4 years) participating in three European cohorts from the EU Child Cohort Network: BiB (United Kingdom), EDEN (France), and INMA (Spain). Eighteen built and food environment, green spaces, road traffic and ambient air pollution exposures were characterized at residential addresses. Various EBRBs were considered as the outcomes including screen time, sleep duration and diet (fruit, vegetables, discretionary sweet foods, sweet beverages) individually and combined into unhealthy lifestyle patterns, using principal components analysis. Associations between urban exposures and outcomes were estimated using a single-exposure analysis and the deletion-substitution-addition algorithm was used to construct multi-exposure models.

RESULTS

In multi-exposure models, greater walkability and smaller distance to the nearest road were associated with higher scores on the unhealthy lifestyle patterns. Likewise, greater walkability was associated with higher screen time and more frequent discretionary sweet food consumption. A smaller distance to the nearest road was also associated with lower sleep duration and more frequent sweet beverages consumption. On the other hand, higher levels of street connectivity showed an inverse association with the unhealthy lifestyle patterns. In the same vein, greater street connectivity was associated with decreased screen time.

CONCLUSION

This comprehensive examination of multiple urban exposures indicates that residing in walkable environments and in close proximity to roads in densely-populated areas may not be advantageous for children EBRBs, while residing in neighborhoods with higher street connectivity appears to supposedly be beneficial.

Association of prenatal exposure to phthalates and synthetic phenols with pubertal development in three European cohorts

BACKGROUND

There is limited epidemiological evidence on the association of prenatal exposure to phthalates and synthetic phenols with altered pubertal timing.

OBJECTIVE

To examine the association of prenatal exposure to phthalates, bisphenol A (BPA), parabens, benzophenone 3 (BP-3), and triclosan (TCS) with pubertal development in girls and boys from three European cohorts.

METHODS

Urinary metabolites of six different phthalate diesters (DEP, DiBP, DnBP, BBzP, DEHP, and DiNP), BPA, methyl- (MePB), ethyl- (EtPB), propyl- (PrPB), and butyl-paraben (BuPB), BP-3, and TCS were quantified in one or two (1st and 3rd trimester) urine samples collected during pregnancy (1999-2008) from mothers in three birth cohorts: INMA (Spain), EDEN (France), and MoBa (Norway). Pubertal development of their children was assessed at a single visit at age 7-12 years (579 girls, 644 boys) using the parent-reported Pubertal Development Scale (PDS). Mixed-effect Poisson and g-computation and Bayesian Kernel Machine Regression (BKMR) were employed to examine associations of individual and combined prenatal chemical exposure, respectively, with the probability of overall pubertal onset, adrenarche, and gonadarche (stage 2+) in girls and boys. Effect modification by child body mass index (BMI) was also assessed.

RESULTS

Maternal concentrations of the molar sum of DEHP and of DiNP metabolites were associated with a slightly higher probability of having started puberty in boys (relative risk, RR [95% CI] = 1.13 [0.98-1.30] and 1.20 [1.06-1.34], respectively, for a two-fold increase in concentrations), with a stronger association for DiNP in boys with overweight or obesity. In contrast, BPA, BuPB, EtPB, and PrPB were associated with a lower probability of pubertal onset, adrenarche, and/or gonadarche in all boys (e.g. overall puberty, BPA: RR [95% CI] = 0.93 [0.85-1.01] and BuPB: 0.95 [0.90-1.00], respectively), and the association with BPA was stronger in boys with underweight/normal weight. In girls, MEHP and BPA were associated with delayed gonadarche in those with underweight/normal weight (RR [95% CI] = 0.86 [0.77-0.95] and 0.90 [0.84-0.97], respectively). Most of these associations were trimester specific. However, the chemical mixture was not associated with any pubertal outcome in boys or girls.

CONCLUSIONS

Prenatal exposure to certain phthalates and synthetic phenols such as BPA may impact the pubertal development of boys, and weight status may modify this effect. BPA may also alter the pubertal development of girls.

The impact of prenatal mercury on neurobehavioral functioning longitudinally assessed from a young age to pre-adolescence in a Spanish birth cohort

The objective is to investigate the relation between cord blood mercury concentrations and child neurobehavioural functioning assessed longitudinally during childhood until pre-adolescence.

METHODS

The study involves mothers and their offspring engaged in the Spanish INMA birth cohort (n = 1147). Total mercury (THg) was determined in cord blood. Behavioural problems were assessed several times during childhood using the ADHD-DSM-IV at age 4, SDQ at ages 7 and 11, CPRS-R:S and the CBCL at ages 7, 9 and 11. Covariates were obtained through questionnaires during the whole period. Multivariate generalised negative binomial (MGNB) models or mixed-effects MGNB (for those tests with information at one or more time points, respectively) were used to investigate the relation between cord blood THg and the children's punctuations. Models were adjusted for prenatal fish intake. Effect modification by sex, prenatal and postnatal fish intake, prenatal fruit and vegetable intake, and maternal polychlorinated biphenyl concentrations (PCBs) was assessed by interaction terms.

RESULTS

The geometric mean ± standard deviation of cord blood THg was 8.22 ± 2.19 μg/L. Despite adjusting for fish consumption, our results did not show any statistically significant relationship between prenatal Hg and the children's performance on behavioural tests conducted between the ages of 4 and 11. Upon assessing the impact of various factors, we observed no statistically significant interaction.

CONCLUSION

Despite elevated prenatal THg exposure, no association was found with children's behavioural functioning assessed from early childhood to pre-adolescence. The nutrients in fish could offset the potential neurotoxic impact of Hg. Further birth cohort studies with longitudinal data are warranted.

Early life exposure to mercury and relationships with telomere length and mitochondrial DNA content in European children

BACKGROUND

Telomere length (TL) and mitochondrial function expressed as mitochondrial DNA copy number (mtDNAcn) are biomarkers of aging and oxidative stress and inflammation, respectively. Methylmercury (MeHg), a common pollutant in fish, induces oxidative stress. We hypothesized that elevated oxidative stress from exposure to MeHg decreases mtDNAcn and shortens TL.

METHODS

Study participants are 6-11-year-old children from the HELIX multi-center birth cohort study, comprising six European countries. Prenatal and postnatal total mercury (THg) concentrations were measured in blood samples, TL and mtDNAcn were determined in child DNA. Covariates and confounders were obtained by questionnaires. Robust regression models were run, considering sociodemographic and lifestyle covariates, as well as fish consumption. Sex, ethnicity, and fish consumption interaction models were also run.

RESULTS

We found longer TL with higher pre- and postnatal THg blood concentrations, even at low-level THg exposure according to the RfD proposed by the US EPA. The prenatal association showed a significant linear relationship with a 3.46 % increase in TL for each unit increased THg. The postnatal association followed an inverted U-shaped marginal non-linear relationship with 1.38 % an increase in TL for each unit increased THg until reaching a cut-point at 0.96 μg/L blood THg, from which TL attrition was observed. Higher pre- and postnatal blood THg concentrations were consistently related to longer TL among cohorts and no modification effect of fish consumption nor children's sex was observed. No association between THg exposure and mtDNAcn was found.

DISCUSSION

We found evidence that THg is associated with TL but the associations seem to be time- and concentration-dependent. Further studies are needed to clarify the mechanism behind the telomere changes of THg and related health effects.

Perinatal exposure to polychlorinated biphenyls (PCBs) and child neurodevelopment: A comprehensive systematic review of outcomes and methodological approaches

BACKGROUND

Polychlorinated biphenyls (PCBs), extensively used in various products, prompt ongoing concern despite reduced exposure since the 1970s. This systematic review explores prenatal PCB and hydroxylated metabolites (OH-PCBs) exposure's association with child neurodevelopment. Encompassing cognitive, motor development, behavior, attention, ADHD, and ASD risks, it also evaluates diverse methodological approaches in studies.

METHODS

PubMed, Embase, PsycINFO, and Web of Science databases were searched through August 23, 2023, by predefined search strings. Peer-reviewed studies published in English were included. The inclusion criteria were: (i) PCBs/OH-PCBs measured directly in maternal and cord blood, placenta or breast milk collected in the perinatal period; (ii) outcomes of cognitive development, motor development, attention, behavior, attention-deficit/hyperactivity disorder (ADHD), and autism spectrum disorder (ASD) among children≤18 years old. Quality assessment followed the National Heart, Lung, and Blood Institute's tool.

RESULTS

Overall, 87 studies were included in this review. We found evidence for the association between perinatal PCB exposure and adverse cognitive development and attention issues in middle childhood. There appeared to be no or negligible link between perinatal PCB exposure and early childhood motor development or the risk of ADHD/ASD. There was an indication of a sex-specific association with worse cognition and attention scores among boys. Some individual studies suggested a possible association between prenatal exposure to OH-PCBs and neurodevelopmental outcomes. There was significant heterogeneity between the studies in exposure markers, exposure assessment timing, outcome assessment, and statistical analysis.

CONCLUSIONS

Significant methodological, clinical and statistical heterogeneity existed in the included studies. Adverse effects on cognitive development and attention were observed in middle childhood. Little or no apparent link on both motor development and risk of ADHD/ASD was observed in early childhood. Inconclusive evidence prevailed regarding other neurodevelopmental aspects due to limited studies. Future research could further explore sex-specific associations and evaluate associations at lower exposure levels post-PCB ban in the US. It should also consider OH-PCB metabolites, co-pollutants, mixtures, and their potential interactions.

Green spaces and respiratory, cardiometabolic, and neurodevelopmental outcomes: An individual-participant data meta-analysis of >35.000 European children

Studies evaluating the benefits and risks of green spaces on children's health are scarce. The present study aimed to examine the associations between exposure to green spaces during pregnancy and early childhood with respiratory, cardiometabolic, and neurodevelopmental outcomes in school-age children. We performed an Individual-Participant Data (IPD) meta-analysis involving 35,000 children from ten European birth cohorts across eight countries. For each participant, we calculated residential Normalized Difference Vegetation Index (NDVI) within a 300 m buffer and the linear distance to green spaces (meters) during prenatal life and childhood. Multiple harmonized health outcomes were selected: asthma and wheezing, lung function, body mass index, diastolic and systolic blood pressure, non-verbal intelligence, internalizing and externalizing problems, and ADHD symptoms. We conducted a two-stage IPD meta-analysis and evaluated effect modification by socioeconomic status (SES) and sex. Between-study heterogeneity was assessed via random-effects meta-regression. Residential surrounding green spaces in childhood, not pregnancy, was associated with improved lung function, particularly higher FEV1 (β = 0.06; 95 %CI: 0.03, 0.09 I2 = 4.03 %, p < 0.001) and FVC (β = 0.07; 95 %CI: 0.04, 0.09 I2 = 0 %, p < 0.001) with a stronger association observed in females (p < 0.001). This association remained robust after multiple testing correction and did not change notably after adjusting for ambient air pollution. Increased distance to green spaces showed an association with lower FVC (β = -0.04; 95 %CI: -0.07, -0.02, I2 = 4.8, p = 0.001), with a stronger effect in children from higher SES backgrounds (p < 0.001). No consistent associations were found between green spaces and asthma, wheezing, cardiometabolic, or neurodevelopmental outcomes, with direction of effect varying across cohorts. Wheezing and neurodevelopmental outcomes showed high between-study heterogeneity, and the age at outcome assessment was only associated with heterogeneity in internalizing problems.. This large European meta-analysis suggests that childhood exposure to green spaces may lead to better lung function. Associations with other respiratory outcomes and selected cardiometabolic and neurodevelopmental outcomes remain inconclusive.

Hair cortisol determinants in 11-year-old children: Environmental, social and individual factors

INTRODUCTION

Children's exposure to chronic stress is associated with several health problems. Measuring hair cortisol concentration is particularly useful for studying chronic stress but much is unknown about hair cortisol determinants in children and adolescents, and previous research has often not considered the simultaneous exposure of multiple variables. This research is focused on investigating the relationship between environmental, social and individual factors with hair cortisol concentration in children.

METHODS

The data used in this study are from the INMA prospective epidemiological cohort study. The assessment of chronic stress was made on the basis of hair samples taken at the age of 11 years in the INMA-Gipuzkoa cohort (n = 346). A metamodel summarizing the hypothesized relationships among environmental, social and individual factors and hair cortisol concentration was constructed based on previous literature. Structural Equation Modelling was performed to examine the relationships among the variables.

RESULTS

In the general model higher behavioural problems were associated with higher cortisol levels and an inverse relationship between environmental noise and cortisol levels was observed, explaining 5 % of the variance in HCC. Once stratified by sex these associations were only hold in boys, while no significant effect of any of the study variables was related with cortisol levels in girls. Importantly, maternal stress was positively related to behavioural difficulties in children. Finally, higher traffic-related air pollution and lower exposure to neighborhood greenness were related to higher environmental noise.

DISCUSSION

This study highlights that simultaneous exposure to different environmental, social and individual characteristics may determine the concentration of hair cortisol. More research is needed and future studies should include this complex view to better understanding of hair cortisol determinants in children.

Socioeconomic position, family context, and child cognitive development

Socioeconomic position (SEP) may have different effects on cognitive development and family context could play a role in this association. This work aimed to analyse the role of socioeconomic positions, measured via various indicators collected longitudinally, in cognitive development at 7-11 years of age, evaluating the role of family context as a potential mediator. The study sample included 394 and 382 children from the INMA Gipuzkoa and Valencia cohorts, respectively. SEP indicators were assessed during pregnancy (family social class, parental education, employment, and disposable income) and at 7 (Gipuzkoa) and 11 (Valencia) years of age (At Risk of Poverty or Social Exclusion (AROPE)). Family context and cognitive development were measured with the Haezi-Etxadi Family Assessment Scale 7-11 (HEFAS 7-11) and Raven's Coloured Progressive Matrices (Raven's CPM), respectively. Linear regression models were developed to assess the relationships between (a) SEP-family context, (b) SEP-cognitive development, and (c) family context-cognitive development, adjusting for a priori-selected confounders. Simple and multiple mediation analyses were performed to explore the role of family context in the SEP-cognitive development relationship. Lower SEP was related with a lower cognitive score, this association being particularly robust for family social class. SEP indicators were related to subscales of family context, in particular those regarding cognitive stimulation, parental stress, and parenting. A relationship was also found between these three subscales and child cognitive development, mediating the effect of family social class on child cognition by 5.2, 5.5, and 10.8%, respectively, and 12.0% jointly.    Conclusion: Both family SEP and context contribute to a child's cognitive development. Equalising policies and positive parenting programmes could contribute to improving cognitive development in children. What is Known: • Parental social class, education, and employment status have been widely employed to measure socioeconomic position. What is New: • This work focuses on standard measurements of socioeconomic position but also other economic indicators such as the EHII and AROPE, and their effect on child cognitive development and family context. • Promotion of cognitive and linguistic development, parental stress and conflict, and parental profile fostering child development mediated the effect of family social class on cognitive development.

Machine learning-based health environmental-clinical risk scores in European children

BACKGROUND

Early life environmental stressors play an important role in the development of multiple chronic disorders. Previous studies that used environmental risk scores (ERS) to assess the cumulative impact of environmental exposures on health are limited by the diversity of exposures included, especially for early life determinants. We used machine learning methods to build early life exposome risk scores for three health outcomes using environmental, molecular, and clinical data.

METHODS

In this study, we analyzed data from 1622 mother-child pairs from the HELIX European birth cohorts, using over 300 environmental, 100 child peripheral, and 18 mother-child clinical markers to compute environmental-clinical risk scores (ECRS) for child behavioral difficulties, metabolic syndrome, and lung function. ECRS were computed using LASSO, Random Forest and XGBoost. XGBoost ECRS were selected to extract local feature contributions using Shapley values and derive feature importance and interactions.

RESULTS

ECRS captured 13%, 50% and 4% of the variance in mental, cardiometabolic, and respiratory health, respectively. We observed no significant differences in predictive performances between the above-mentioned methods.The most important predictive features were maternal stress, noise, and lifestyle exposures for mental health; proteome (mainly IL1B) and metabolome features for cardiometabolic health; child BMI and urine metabolites for respiratory health.

CONCLUSIONS

Besides their usefulness for epidemiological research, our risk scores show great potential to capture holistic individual level non-hereditary risk associations that can inform practitioners about actionable factors of high-risk children. As in the post-genetic era personalized prevention medicine will focus more and more on modifiable factors, we believe that such integrative approaches will be instrumental in shaping future healthcare paradigms.

Prenatal Exposure to Chemical Mixtures and Metabolic Syndrome Risk in Children

Importance

Prenatal exposure to ubiquitous endocrine-disrupting chemicals (EDCs) may increase the risk of metabolic syndrome (MetS) in children, but few studies have studied chemical mixtures or explored underlying protein and metabolic signatures.

Objective

To investigate associations of prenatal exposure to EDC mixtures with MetS risk score in children and identify associated proteins and metabolites.

Design, Setting, and Participants

This population-based, birth cohort study used data collected between April 1, 2003, and February 26, 2016, from the Human Early Life Exposome cohort based in France, Greece, Lithuania, Norway, Spain, and the UK. Eligible participants included mother-child pairs with measured prenatal EDC exposures and complete data on childhood MetS risk factors, proteins, and metabolites. Data were analyzed between October 2022 and July 2023.

Exposures

Nine metals, 3 organochlorine pesticides, 5 polychlorinated biphenyls, 2 polybrominated diphenyl ethers (PBDEs), 5 perfluoroalkyl substances (PFAS), 10 phthalate metabolites, 3 phenols, 4 parabens, and 4 organophosphate pesticide metabolites measured in urine and blood samples collected during pregnancy.

Main Outcomes and Measures

At 6 to 11 years of age, a composite MetS risk score was constructed using z scores of waist circumference, systolic and diastolic blood pressures, triglycerides, high-density lipoprotein cholesterol, and insulin levels. Childhood levels of 44 urinary metabolites, 177 serum metabolites, and 35 plasma proteins were quantified using targeted methods. Associations were assessed using bayesian weighted quantile sum regressions applied to mixtures for each chemical group.

Results

The study included 1134 mothers (mean [SD] age at birth, 30.7 [4.9] years) and their children (mean [SD] age, 7.8 [1.5] years; 617 male children [54.4%] and 517 female children [45.6%]; mean [SD] MetS risk score, -0.1 [2.3]). MetS score increased per 1-quartile increase of the mixture for metals (β = 0.44; 95% credible interval [CrI], 0.30 to 0.59), organochlorine pesticides (β = 0.22; 95% CrI, 0.15 to 0.29), PBDEs (β = 0.17; 95% CrI, 0.06 to 0.27), and PFAS (β = 0.19; 95% CrI, 0.14 to 0.24). High-molecular weight phthalate mixtures (β = -0.07; 95% CrI, -0.10 to -0.04) and low-molecular weight phthalate mixtures (β = -0.13; 95% CrI, -0.18 to -0.08) were associated with a decreased MetS score. Most EDC mixtures were associated with elevated proinflammatory proteins, amino acids, and altered glycerophospholipids, which in turn were associated with increased MetS score.

Conclusions and Relevance

This cohort study suggests that prenatal exposure to EDC mixtures may be associated with adverse metabolic health in children. Given the pervasive nature of EDCs and the increase in MetS, these findings hold substantial public health implications.

Green space exposure and blood DNA methylation at birth and in childhood - A multi-cohort study

Green space exposure has been associated with improved mental, physical and general health. However, the underlying biological mechanisms remain largely unknown. The aim of this study was to investigate the association between green space exposure and cord and child blood DNA methylation. Data from eight European birth cohorts with a total of 2,988 newborns and 1,849 children were used. Two indicators of residential green space exposure were assessed: (i) surrounding greenness (satellite-based Normalized Difference Vegetation Index (NDVI) in buffers of 100 m and 300 m) and (ii) proximity to green space (having a green space ≥ 5,000 m2 within a distance of 300 m). For these indicators we assessed two exposure windows: (i) pregnancy, and (ii) the period from pregnancy to child blood DNA methylation assessment, named as cumulative exposure. DNA methylation was measured with the Illumina 450K or EPIC arrays. To identify differentially methylated positions (DMPs) we fitted robust linear regression models between pregnancy green space exposure and cord blood DNA methylation and between cumulative green space exposure and child blood DNA methylation. Two sensitivity analyses were conducted: (i) without adjusting for cellular composition, and (ii) adjusting for air pollution. Cohort results were combined through fixed-effect inverse variance weighted meta-analyses. Differentially methylated regions (DMRs) were identified from meta-analysed results using the Enmix-combp and DMRcate methods. There was no statistical evidence of pregnancy or cumulative exposures associating with any DMP (False Discovery Rate, FDR, p-value < 0.05). However, surrounding greenness exposure was inversely associated with four DMRs (three in cord blood and one in child blood) annotated to ADAMTS2, KCNQ1DN, SLC6A12 and SDK1 genes. Results did not change substantially in the sensitivity analyses. Overall, we found little evidence of the association between green space exposure and blood DNA methylation. Although we identified associations between surrounding greenness exposure with four DMRs, these findings require replication.

Childhood exposure to outdoor air pollution in different microenvironments and cognitive and fine motor function in children from six European cohorts

BACKGROUND

Exposure to air pollution during childhood has been linked with adverse effects on cognitive development and motor function. However, limited research has been done on the associations of air pollution exposure in different microenvironments such as home, school, or while commuting with these outcomes.

OBJECTIVE

To analyze the association between childhood air pollution exposure in different microenvironments and cognitive and fine motor function from six European birth cohorts.

METHODS

We included 1301 children from six European birth cohorts aged 6-11 years from the HELIX project. Average outdoor air pollutants concentrations (NO2, PM2.5) were estimated using land use regression models for different microenvironments (home, school, and commute), for 1-year before the outcome assessment. Attentional function, cognitive flexibility, non-verbal intelligence, and fine motor function were assessed using the Attention Network Test, Trail Making Test A and B, Raven Colored Progressive Matrices test, and the Finger Tapping test, respectively. Adjusted linear regressions models were run to determine the association between each air pollutant from each microenvironment on each outcome.

RESULTS

In pooled analysis we observed high correlation (rs = 0.9) between air pollution exposures levels at home and school. However, the cohort-by-cohort analysis revealed correlations ranging from low to moderate. Air pollution exposure levels while commuting were higher than at home or school. Exposure to air pollution in the different microenvironments was not associated with working memory, attentional function, non-verbal intelligence, and fine motor function. Results remained consistently null in random-effects meta-analysis.

CONCLUSIONS

No association was observed between outdoor air pollution exposure in different microenvironments (home, school, commute) and cognitive and fine motor function in children from six European birth cohorts. Future research should include a more detailed exposure assessment, considering personal measurements and time spent in different microenvironments.

Ambient air temperature exposure and foetal size and growth in three European birth cohorts

INTRODUCTION

Ambient air temperature may affect birth outcomes adversely, but little is known about their impact on foetal growth throughout pregnancy. We evaluated the association between temperature exposure during pregnancy and foetal size and growth in three European birth cohorts.

METHODS

We studied 23,408 pregnant women from the English Born in Bradford cohort, Dutch Generation R Study, and Spanish INMA Project. Using the UrbClimTM model, weekly ambient air temperature exposure at 100x100m resolution at the mothers' residences during pregnancy was calculated. Estimated foetal weight, head circumference, and femur length at mid and late pregnancy and weight, head circumference, and length at birth were converted into standard deviation scores (SDS). Foetal growth from mid to late pregnancy was calculated (grams or centimetres/week). Cohort/region-specific distributed lag non-linear models were combined using a random-effects meta-analysis and results presented in reference to the median percentile of temperature (14 °C).

RESULTS

Weekly temperatures ranged from -5.6 (Bradford) to 30.3 °C (INMA-Sabadell). Cold and heat exposure during weeks 1-28 were associated with a smaller and larger head circumference in late pregnancy, respectively (e.g., for 9.5 °C: -1.6 SDS [95 %CI -2.0; -0.4] and for 20.0 °C: 1.8 SDS [0.7; 2.9]). A susceptibility period from weeks 1-7 was identified for cold exposure and a smaller head circumference at late pregnancy. Cold exposure was associated with a slower head circumference growth from mid to late pregnancy (for 5.5 °C: -0.1 cm/week [-0.2; -0.04]), with a susceptibility period from weeks 4-12. No associations that survived multiple testing correction were found for other foetal or any birth outcomes.

CONCLUSIONS

Cumulative exposure to cold and heat during pregnancy was associated with changes in foetal head circumference throughout gestation, with susceptibility periods for cold during the first pregnancy trimester. No associations were found at birth, suggesting potential recovery. Future research should replicate this study across different climatic regions including varying temperature profiles.

Pro-vegetarian dietary patterns and essential and heavy metal exposure in children of 4-5-years from the INfancia y medio Ambiente cohort (INMA)

Dietary patterns provide a comprehensive assessment of food consumption, including essential nutrients and potential exposure to environmental contaminants. While pro-vegetarian (PVG) dietary patterns have shown health benefits in adults, their effects on children are less well studied. This study aims to explore the association between children's adherence to the most common PVG dietary patterns and their exposure to metals, assessed through urine concentration. In our study, we included a population of 723 children aged 4-5-years from the INfancia y Medio Ambiente (INMA) cohort in Spain. We calculated three predefined PVG dietary patterns, namely general (gPVG), healthful (hPVG), and unhealthful (uPVG), using dietary information collected through a validated Food Frequency Questionnaire. Urinary concentrations of various essential and heavy metals (Co, Cu, Zn, Se, Mo, Pb, and Cd) were measured using mass spectrometry. Additionally, urinary arsenic speciation, including arsenobetaine (AsB), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA), and inorganic arsenic (iAs), was measured. The sum of urinary MMA and iAs was used to assess iAs exposure. We estimated primary (PMI) and secondary iAs methylation (SMI) indices. To explore the association between PVG dietary patterns in quintiles and metal exposure, we utilized multiple-adjusted linear regression models and the quantile g-computation approach. Compared with the lowest quintile, participants in the highest quintile of gPVG showed a 22.7% lower urinary Co (95% confidence interval (CI): -38.7; -1.98) and a 12.6% lower Se (95%CI: -22.9; -1.00) concentrations. Second quintile of adherence to hPVG was associated with a 51.7% lower urinary iAs + MMA concentrations (95%CI: -74.3; -8.61). Second quintile of adherence to an uPVG was associated with a 13.6% lower Se levels (95%CI: -22.9; -2.95) while the third quintile to this pattern was associated with 17.5% lower Mo concentrations (95%CI: -29.5; -2.95). The fourth quintile of adherence to gPVG was associated with a 68.5% higher PMI and a 53.7% lower SMI. Our study showed that adherence to a gPVG dietary pattern in childhood may modestly reduce the intakes of some essential metals such as Co and Se. Further investigations are warranted to explore any potential health implications.

Nitrogen dioxide exposure, attentional function, and working memory in children from 4 to 8 years: Periods of susceptibility from pregnancy to childhood

BACKGROUND

Air pollution exposure during pregnancy and childhood has been linked to executive function impairment in children, however, very few studies have assessed these two exposure periods jointly to identify susceptible periods of exposure. We sought to identify potential periods of susceptibility of nitrogen dioxide (NO2) exposure from conception to childhood on attentional function and working memory in school-aged children.

METHODS

Within the Spanish INMA Project, we estimated residential daily NO2 exposures during pregnancy and up to 6 years of childhood using land use regression models (n = 1,703). We assessed attentional function at 4-6 years and 6-8 years, using the Conners Kiddie Continuous Performance Test and the Attention Network Test, respectively, and working memory at 6-8 years, using the N-back task. We used distributed lag non-linear models to assess the periods of susceptibility of each outcome, adjusting for potential confounders and correcting for multiple testing. We also stratified all models by sex.

RESULTS

Higher exposure to NO2 between 1.3 and 1.6 years of age was associated with higher hit reaction time standard error (HRT-SE) (0.14 ms (95 % CI 0.05; 0.22) per 10 μg/m3 increase in NO2) and between 1.5 and 2.2 years of age with more omission errors (1.02 (95 % CI 1.01; 1.03) of the attentional function test at 4-6 years. Higher exposure to NO2 between 0.3 and 2.2 years was associated with higher HRT-SE (10.61 ms (95 % CI 3.46; 17.75) at 6-8 years only in boys. We found no associations between exposure to NO2 and working memory at 6-8 years.

CONCLUSION

Our findings suggest that NO2 exposure during the first two years of life is associated with poorer attentional function in children from 4 to 8 years of age, especially in boys. These findings highlight the importance of exploring long-term effects of traffic-related air pollution exposure in older age groups.

Maternal Seafood Consumption during Pregnancy and Cardiovascular Health of Children at 11 Years of Age

Nutrition is critical during pregnancy for the healthy growth of the developing infant, who is fully dependent on maternal dietary omega-3 supply for development. Fatty fish, a main dietary source of omega-3, is associated with decreased cardiovascular risk in adults. We conducted a longitudinal study based on a mother-offspring cohort as part of the project Infancia y Medio Ambiente (INMA) in order to assess whether fish intake during pregnancy relates to cardiovascular health in children. A total of 657 women were included and followed throughout pregnancy until birth, and their children were enrolled at birth and followed up until age 11-12. A semi-quantitative food frequency questionnaire was used to assess the daily intake of foods during the 1st and 3rd trimesters of pregnancy. Cardiovascular assessments included arterial stiffness (assessed by carotid-femoral pulse wave velocity [PWV]) and retinal microcirculation (photographic assessment of central retinal arteriolar and venular equivalent [CRAE and CRVE]). The association between maternal fish consumption and cardiovascular outcomes of offspring at 11 years of age was evaluated using multivariable linear regression models. There were no statistically significant differences in any cardiovascular endpoint in children whose mothers had a higher fish consumption during pregnancy compared to those with a lower fish consumption. We found a slightly higher PWV (β = 0.1, 95% CI = 0.0; 0.2, p for trend = 0.047) in children whose mothers had a higher consumption of canned tuna during the 1st trimester of pregnancy. Fish intake during pregnancy was found to be unrelated to the offspring's cardiovascular health at 11 years of age. The beneficial cardiovascular effects of fish consumption during pregnancy on the offspring are still inconclusive.

Relation of prenatal and postnatal PM2.5 exposure with cognitive and motor function among preschool-aged children

The literature informing susceptible periods of exposure on children's neurodevelopment is limited. We evaluated the impacts of pre- and postnatal fine particulate matter (PM2.5) exposure on children's cognitive and motor function among 1303 mother-child pairs in the Spanish INMA (Environment and Childhood) Study. Random forest models with temporal back extrapolation were used to estimate daily residential PM2.5 exposures that we averaged across 1-week lags during the prenatal period and 4-week lags during the postnatal period. The McCarthy Scales of Children's Abilities (MSCA) were administered around 5 years to assess general cognitive index (GCI) and several subscales (verbal, perceptual-performance, memory, fine motor, gross motor). We applied distributed lag nonlinear models within the Bayesian hierarchical framework to explore periods of susceptibility to PM2.5 on each MSCA outcome. Effect estimates were calculated per 5 μg/m3 increase in PM2.5 and aggregated across adjacent statistically significant lags using cumulative β (βcum) and 95% Credible Intervals (95%CrI). We evaluated interactions between PM2.5 with fetal growth and child sex. We did not observe associations of PM2.5 exposure with lower GCI scores. We found a period of susceptibility to PM2.5 on fine motor scores in gestational weeks 1-9 (βcum = -2.55, 95%CrI = -3.53,-1.56) and on gross motor scores in weeks 7-17 (βcum = -2.27,95%CrI = -3.43,-1.11) though the individual lags for the latter were only borderline statistically significant. Exposure in gestational week 17 was weakly associated with verbal scores (βcum = -0.17, 95%CrI = -0.26,-0.09). In the postnatal period (from age 0.5-1.2 years), we observed a window of susceptibility to PM2.5 on lower perceptual-performance (β = -2.42, 95%CrI = -3.37,-1.46). Unexpected protective associations were observed for several outcomes with exposures in the later postnatal period. We observed no evidence of differences in susceptible periods by fetal growth or child sex. Preschool-aged children's motor function may be particularly susceptible to PM2.5 exposures experienced in utero whereas the first year of life was identified as a period of susceptibility to PM2.5 for children's perceptual-performance.

Association of exposure to mixture of chemicals during pregnancy with cognitive abilities and fine motor function of children

Chemical exposures often occur in mixtures and exposures during pregnancy may lead to adverse effects on the fetal brain, potentially reducing lower cognitive abilities and fine motor function of the child. We investigated the association of motheŕs exposure to a mixture of chemicals during pregnancy (i.e., organochlorine compounds, per- and polyfluoroalkyl substances, phenols, phthalates, organophosphate pesticides) with cognitive abilties and fine motor function in their children. We studied 1097 mother-child pairs from five European cohorts participating in the Human Early Life Exposome study (HELIX). Measurement of 26 biomarkers of exposure to chemicals was performed on urine or blood samples of pregnant women (mean age 31 years). Cognitive abilities and fine motor function were assessed in their children (mean age 8 years) with a battery of computerized tests administered in person (Raveńs Coloured Progressive Matrices, Attention Network Test, N-back Test, Trail Making Test, Finger Tapping Test). We estimated the joint effect of prenatal exposure to chemicals on cognitive abilities and fine motor function using the quantile-based g-computation method, adjusting for sociodemographic characteristics. A quartile increase in all the chemicals in the overall mixture was associated with worse fine motor function, specifically lower scores in the Finger Tapping Test [-8.5 points, 95 % confidence interval (CI) -13.6 to -3.4; -14.5 points, 95 % CI -22.4 to -6.6, and -18.0 points, 95 % CI -28.6 to -7.4) for the second, third and fourth quartile of the overal mixture, respectively, when compared to the first quartile]. Organochlorine compounds, phthalates, and per- and polyfluoroalkyl substances contributed most to this association. We did not find a relationship with cognitive abilities. We conclude that exposure to chemical mixtures during pregnancy may influence neurodevelopment, impacting fine motor function of the offspring.

Susceptible windows of prenatal and postnatal fine particulate matter exposures and attention-deficit hyperactivity disorder symptoms in early childhood

Few prior studies have explored windows of susceptibility to fine particulate matter (PM2.5) in both the prenatal and postnatal periods and children's attention-deficit/hyperactivity disorder (ADHD) symptoms. We analyzed data from 1416 mother-child pairs from the Spanish INMA (INfancia y Medio Ambiente) Study (2003-2008). Around 5 years of age, teachers reported the number of ADHD symptoms (i.e., inattention, hyperactivity/impulsivity) using the ADHD Diagnostic and Statistical Manual of Mental Disorders. Around 7 years of age, parents completed the Conners' Parent Rating Scales, from which we evaluated the ADHD index, cognitive problems/inattention, hyperactivity, and oppositional subscales, reported as age- and sex-standardized T-scores. Daily residential PM2.5 exposures were estimated using a two-stage random forest model with temporal back-extrapolation and averaged over 1-week periods in the prenatal period and 4-week periods in the postnatal period. We applied distributed lag non-linear models within the Bayesian hierarchical model framework to identify susceptible windows of prenatal or postnatal exposure to PM2.5 (per 5-μg/m3) for ADHD symptoms. Models were adjusted for relevant covariates, and cumulative effects were reported by aggregating risk ratios (RRcum) or effect estimates (βcum) across adjacent susceptible windows. A similar susceptible period of exposure to PM2.5 (1.2-2.9 and 0.9-2.7 years of age, respectively) was identified for hyperactivity/impulsivity symptoms assessed ~5 years (RRcum = 2.72, 95% credible interval [CrI] = 1.98, 3.74) and increased hyperactivity subscale ~7 years (βcum = 3.70, 95% CrI = 2.36, 5.03). We observed a susceptibility period to PM2.5 on risk of hyperactivity/impulsivity symptoms ~5 years in gestational weeks 16-22 (RRcum = 1.36, 95% CrI = 1.22, 1.52). No associations between PM2.5 exposure and other ADHD symptoms were observed. We report consistent evidence of toddlerhood as a susceptible window of PM2.5 exposure for hyperactivity in young children. Although mid-pregnancy was identified as a susceptible period of exposure on hyperactivity symptoms in preschool-aged children, this association was not observed at the time children were school-aged.

Associated factors with mycotoxin exposure in Spanish population

Human exposure to mycotoxins is a global concern since filamentous fungi can contaminate food and feed from crops to ready-to-eat meals. Human urine biomonitoring is a widely used technique to evaluate mycotoxins exposure, as an alternative to food correlation studies. The aim of this study is to describe human exposure to mycotoxins and to investigate the associated sociodemographic, lifestyle and dietary variables. Participants were 540 women from the Valencia (Spain) cohort of the Spanish Childhood and Environment Project (INMA). A validated multi-mycotoxin method using HPLC-Q-TOF-MS was applied to determine the concentration of ten selected mycotoxins: Enniatin A, Enniatin B, Enniatin A1, Enniatin B1, Beauvericine, Aflatoxin B1, Aflatoxin B2, Aflatoxin G1, Aflatoxin G2 and Ochratoxin A. A simultaneous untargeted screening of mycotoxins and their metabolites has been performed. Mycotoxins associations were assessed by bivariate and multivariate regression models using participants' sociodemographic, lifestyle and dietary data collected through questionnaires. Mycotoxins were detected in 81% of urine samples. The method quantified mycotoxins concentrations in up to 151 samples. Most quantified mycotoxins were: Enniatin B [% of detection (concentration range)] = 26% (1.0-39.7 ng/mg) and Enniatin B1 = 7% (0.5-14.4 ng/mg). Besides the ten-targeted mycotoxins, other mycotoxins and metabolites were studied, and higher incidence was observed for Deepoxy-deoxynivalenol (45%), Ochratoxin B (18%) and Ochratoxin α (17%). Higher mycotoxins concentrations were associated with rural areas as well as with participants belonged to lower social class, beer, light sodas and fruit juice consumers. On the contrary, higher processed meat intake was related to lower mycotoxins' levels. Studies are required to better evaluate the exposure to mycotoxins from food and their environmental relationships.

Integrating multiple lines of evidence to assess the effects of maternal BMI on pregnancy and perinatal outcomes

BACKGROUND

Higher maternal pre-pregnancy body mass index (BMI) is associated with adverse pregnancy and perinatal outcomes. However, whether these associations are causal remains unclear.

METHODS

We explored the relation of maternal pre-/early-pregnancy BMI with 20 pregnancy and perinatal outcomes by integrating evidence from three different approaches (i.e. multivariable regression, Mendelian randomisation, and paternal negative control analyses), including data from over 400,000 women.

RESULTS

All three analytical approaches supported associations of higher maternal BMI with lower odds of maternal anaemia, delivering a small-for-gestational-age baby and initiating breastfeeding, but higher odds of hypertensive disorders of pregnancy, gestational hypertension, preeclampsia, gestational diabetes, pre-labour membrane rupture, induction of labour, caesarean section, large-for-gestational age, high birthweight, low Apgar score at 1 min, and neonatal intensive care unit admission. For example, higher maternal BMI was associated with higher risk of gestational hypertension in multivariable regression (OR = 1.67; 95% CI = 1.63, 1.70 per standard unit in BMI) and Mendelian randomisation (OR = 1.59; 95% CI = 1.38, 1.83), which was not seen for paternal BMI (OR = 1.01; 95% CI = 0.98, 1.04). Findings did not support a relation between maternal BMI and perinatal depression. For other outcomes, evidence was inconclusive due to inconsistencies across the applied approaches or substantial imprecision in effect estimates from Mendelian randomisation.

CONCLUSIONS

Our findings support a causal role for maternal pre-/early-pregnancy BMI on 14 out of 20 adverse pregnancy and perinatal outcomes. Pre-conception interventions to support women maintaining a healthy BMI may reduce the burden of obstetric and neonatal complications.

FUNDING

Medical Research Council, British Heart Foundation, European Research Council, National Institutes of Health, National Institute for Health Research, Research Council of Norway, Wellcome Trust.

Influence of perinatal and childhood exposure to tobacco and mercury in children's gut microbiota

Background

Early life determinants of the development of gut microbiome composition in infants have been widely investigated; however, if early life pollutant exposures, such as tobacco or mercury, have a persistent influence on the gut microbial community, its stabilization at later childhood remains largely unknown.

Objective

In this exposome-wide study, we aimed at identifying the contribution of exposure to tobacco and mercury from the prenatal period to childhood, to individual differences in the fecal microbiome composition of 7-year-old children, considering co-exposure to a width of established lifestyle and clinical determinants.

Methods

Gut microbiome was studied by 16S rRNA amplicon sequencing in 151 children at the genus level. Exposure to tobacco was quantified during pregnancy through questionnaire (active tobacco consumption, second-hand smoking -SHS) and biomonitoring (urinary cotinine) at 4 years (urinary cotinine, SHS) and 7 years (SHS). Exposure to mercury was quantified during pregnancy (cord blood) and at 4 years (hair). Forty nine other potential environmental determinants (12 at pregnancy/birth/infancy, 15 at 4 years and 22 at 7 years, such as diet, demographics, quality of living/social environment, and clinical records) were registered. We used multiple models to determine microbiome associations with pollutants including multi-determinant multivariate analysis of variance and linear correlations (wUnifrac, Bray-Curtis and Aitchison ß-diversity distances), single-pollutant permutational multivariate analysis of variance adjusting for co-variates (Aitchison), and multivariable association model with single taxa (MaAsLin2; genus). Sensitivity analysis was performed including genetic data in a subset of 107 children.

Results

Active smoking in pregnancy was systematically associated with microbiome composition and ß-diversity (R2 2-4%, p < 0.05, Aitchison), independently of other co-determinants. However, in the adjusted single pollutant models (PERMANOVA), we did not find any significant association. An increased relative abundance of Dorea and decreased relative abundance of Akkermansia were associated with smoking during pregnancy (q < 0.05).

Discussion

Our findings suggest a long-term sustainable effect of prenatal tobacco exposure on the children's gut microbiota. This effect was not found for mercury exposure or tobacco exposure during childhood. Assessing the role of these exposures on the children's microbiota, considering multiple environmental factors, should be further investigated.

Sleep duration in preschool age and later behavioral and cognitive outcomes: an individual participant data meta-analysis in five European cohorts

Short sleep duration has been linked to adverse behavioral and cognitive outcomes in schoolchildren, but few studies examined this relation in preschoolers. We aimed to investigate the association between parent-reported sleep duration at 3.5 years and behavioral and cognitive outcomes at 5 years in European children. We used harmonized data from five cohorts of the European Union Child Cohort Network: ALSPAC, SWS (UK); EDEN, ELFE (France); INMA (Spain). Associations were estimated through DataSHIELD using adjusted generalized linear regression models fitted separately for each cohort and pooled with random-effects meta-analysis. Behavior was measured with the Strengths and Difficulties Questionnaire. Language and non-verbal intelligence were assessed by the Wechsler Preschool and Primary Scale of Intelligence or the McCarthy Scales of Children's Abilities. Behavioral and cognitive analyses included 11,920 and 2981 children, respectively (34.0%/13.4% of the original sample). In meta-analysis, longer mean sleep duration per day at 3.5 years was associated with lower mean internalizing and externalizing behavior percentile scores at 5 years (adjusted mean difference: - 1.27, 95% CI [- 2.22, - 0.32] / - 2.39, 95% CI [- 3.04, - 1.75]). Sleep duration and language or non-verbal intelligence showed trends of inverse associations, however, with imprecise estimates (adjusted mean difference: - 0.28, 95% CI [- 0.83, 0.27] / - 0.42, 95% CI [- 0.99, 0.15]). This individual participant data meta-analysis suggests that longer sleep duration in preschool age may be important for children's later behavior and highlight the need for larger samples for robust analyses of cognitive outcomes. Findings could be influenced by confounding or reverse causality and require replication.

Association between residential exposure to road traffic noise and cognitive and motor function outcomes in children and preadolescents

BACKGROUND

Exposure to environmental noise is increasing in recent years but most of the previous literature in children has evaluated the effect of aircraft noise exposure at schools on cognition.

OBJECTIVE

To assess whether residential exposure to road traffic noise during pregnancy and childhood is associated with cognitive and motor function in children and preadolescents.

METHODS

The study involved 619 participants from the Spanish INMA-Sabadell cohort and 7,115 from the Dutch Generation R Study. We used noise maps to estimate the average day-evening-night road traffic noise levels at each participant's residential address during pregnancy and childhood periods. Validated tests were administered throughout childhood in both cohorts to assess non-verbal and verbal intelligence, memory, processing speed, attentional function, working memory, cognitive flexibility, risky decision-making, and fine and gross motor function. Linear models, linear mixed models, and negative binomial models were run depending on the outcome in cohort-specific analysis and combined with a random-effects meta-analysis. All models were adjusted for several socioeconomic and lifestyle variables and results corrected for multiple testing.

RESULTS

Average road traffic noise exposure levels during pregnancy and childhood were 61.3 (SD 6.0) and 61.5 (SD 5.4) dB for the INMA-Sabadell cohort and 54.6 (SD 7.9) and 53.5 (SD 6.5) dB for the Generation R Study, respectively. Road traffic noise exposure during pregnancy and childhood was not related to any of the cognitive and motor function outcomes examined in this study (e.g. -0.92 (95 % CI -2.08; 0.24) and 0.20 (95 % CI -0.96; 1.35) in overall estimates of memory and fine motor function, respectively, when road traffic noise increases by 10 dB during childhood).

CONCLUSIONS

These findings suggest that child's cognitive or motor functions are not affected by residential exposure to road traffic noise. However, more studies evaluating this association at school and home settings as well as noise events are needed.

A meta-analysis of epigenome-wide association studies on pregnancy vitamin B12 concentrations and offspring DNA methylation

Circulating vitamin B12 concentrations during pregnancy are associated with offspring health. Foetal DNA methylation changes could underlie these associations. Within the Pregnancy And Childhood Epigenetics Consortium, we meta-analysed epigenome-wide associations of circulating vitamin B12 concentrations in mothers during pregnancy (n = 2,420) or cord blood (n = 1,029), with cord blood DNA methylation. Maternal and newborn vitamin B12 concentrations were associated with DNA methylation at 109 and 7 CpGs, respectively (False Discovery Rate P-value <0.05). Persistent associations with DNA methylation in the peripheral blood of up to 482 children aged 4-10 y were observed for 40.7% of CpGs associated with maternal vitamin B12 and 57.1% of CpGs associated with newborn vitamin B12. Of the CpGs identified in the maternal meta-analyses, 4.6% were associated with either birth weight or gestational age in a previous work. For the newborn meta-analysis, this was the case for 14.3% of the identified CpGs. Also, of the CpGs identified in the newborn meta-analysis, 14.3% and 28.6%, respectively, were associated with childhood cognitive skills and nonverbal IQ. Of the 109 CpGs associated with maternal vitamin B12, 18.3% were associated with nearby gene expression. In this study, we showed that maternal and newborn vitamin B12 concentrations are associated with DNA methylation at multiple CpGs in offspring blood (PFDR<0.05). Whether this differential DNA methylation underlies associations of vitamin B12 concentrations with child health outcomes, such as birth weight, gestational age, and childhood cognition, should be further examined in future studies.

Lifestyle patterns in European preschoolers: Associations with socio-demographic factors and body mass index

BACKGROUND

Energy balance-related behaviours (EBRBs), that is, dietary intake, screen, outdoor play and sleep, tend to combine into 'lifestyle patterns', with potential synergistic influences on health. To date, studies addressing this theme mainly focused on school children and rarely accounted for sleep, with a cross-country perspective.

OBJECTIVES

We aimed at comparing lifestyle patterns among preschool-aged children across Europe, their associations with socio-demographic factors and their links with body mass index (BMI).

METHODS

Harmonized data on 2-5-year-olds participating in nine European birth cohorts from the EU Child Cohort Network were used (EBRBs, socio-demographics and anthropometrics). Principal component analysis and multivariable linear and logistic regressions were performed.

RESULTS

The most consistent pattern identified across cohorts was defined by at least three of the following EBRBs: discretionary consumption, high screen time, low outdoor play time and low sleep duration. Consistently, children from low-income households and born to mothers with low education level had higher scores on this pattern compared to their socioeconomically advantaged counterparts. Furthermore, it was associated with higher BMI z-scores in the Spanish and Italian cohorts (β = 0.06, 95% CI = [0.02; 0.10], both studies).

CONCLUSION

These findings may be valuable in informing early multi-behavioural interventions aimed at reducing social inequalities in health at a European scale.

Sociodemographic, lifestyle, and environmental determinants of vitamin D levels in pregnant women in Spain

INTRODUCTION

Vitamin D deficiency (<20 ng/mL circulating levels) is a worldwide public health concern and pregnant women are especially vulnerable, affecting the health of the mother and the fetus. This study aims to evaluate the sociodemographic, lifestyle, and environmental determinants associated with circulating vitamin D levels in Spanish pregnant women.

METHODS

We used data from the Spanish INMA ("Infancia y Medio Ambiente") prospective birth cohort study from the regions of Gipuzkoa, Sabadell, and Valencia. 25-hydroxyvitamin D3 (25(OH)D3) was measured in plasma collected in the first trimester of pregnancy. Information on 108 determinants was gathered: 13 sociodemographic, 48 lifestyle including diet, smoking and physical activity, and 47 environmental variables, representing the urban and the chemical exposome. Association of the determinants with maternal 25(OH)D3 levels was estimated in single- and multiple-exposure models. Machine learning techniques were used to predict 25(OH)D3 levels below sufficiency (30 ng/mL).

RESULTS

The prevalence of < 30 ng/mL 25(OH)D3 levels was 51 %. In the single-exposure analysis, older age, higher socioeconomic status, taking vitamin D, B12 and other sup*plementation, and higher humidity, atmospheric pressure and UV rays were associated with higher levels of 25(OH)D3 (IQR increase of age: 1.2 [95 % CI: 0.6, 1.8] ng/mL 25(OH)D3). In the multiple-exposures model, most of these associations remained and others were revealed. Higher body mass index, PM2.5 and high deprivation area were associated with lower 25(OH)D3 levels (i.e., Quartile 4 of PM2.5 vs Q1: -3.6 [95 % CI: -5.6, -1.5] ng/mL of 25(OH)D3). History of allergy and asthma, being multiparous, intake of vegetable fat, vitamin B6, alcohol consumption and molybdenum were associated with higher levels. The machine learning classification model confirmed some of these associations.

CONCLUSIONS

This comprehensive study shows that younger age, higher body mass index, higher deprived areas, higher air pollution and lower UV rays and humidity are associated with lower 25(OH)D3 levels.

DNA methylation at birth and fine motor ability in childhood: an epigenome-wide association study with replication

Lower fine motor performance in childhood has been associated with poorer cognitive development and neurodevelopmental conditions such as autism spectrum disorder, yet, biological underpinnings remain unclear. DNA methylation (DNAm), an essential process for healthy neurodevelopment, is a key molecular system of interest. In this study, we conducted the first epigenome-wide association study of neonatal DNAm with childhood fine motor ability and further examined the replicability of epigenetic markers in an independent cohort. The discovery study was embedded in Generation R, a large population-based prospective cohort, including a subsample of 924 ~ 1026 European-ancestry singletons with available data on DNAm in cord blood and fine motor ability at a mean (SD) age of 9.8 (0.4) years. Fine motor ability was measured using a finger-tapping test (3 subtests including left-, right-hand and bimanual), one of the most frequently used neuropsychological instruments of fine motor function. The replication study comprised 326 children with a mean (SD) age of 6.8 (0.4) years from an independent cohort, the INfancia Medio Ambiente (INMA) study. Four CpG sites at birth were prospectively associated with childhood fine motor ability after genome-wide correction. Of these, one CpG (cg07783800 in GNG4) was replicated in INMA, showing that lower levels of methylation at this site were associated with lower fine motor performance in both cohorts. GNG4 is highly expressed in the brain and has been implicated in cognitive decline. Our findings support a prospective, reproducible association between DNAm at birth and fine motor ability in childhood, pointing to GNG4 methylation at birth as a potential biomarker of fine motor ability.

Influence of genetic polymorphisms on arsenic methylation efficiency during pregnancy: Evidence from a Spanish birth cohort

BACKGROUND

Inorganic arsenic (iAs) is a widespread toxic metalloid. It is well-known that iAs metabolism and its toxicity are mediated by polymorphisms in AS3MT and other genes. However, studies during pregnancy are scarce. We aimed to examine the role of genetic polymorphisms in AS3MT, GSTO2, N6AMT1, MTHFR, MTR, FTCD, CBS, and FOLH1 in iAs methylation efficiency during pregnancy.

METHODS

The study included 541 pregnant participants from the INMA (Environment and Childhood) Spanish cohort. Using high-performance liquid chromatography coupled to inductively coupled plasma-tandem mass, we measured arsenic (iAs and the metabolites monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA)) in urine samples collected during the first trimester. iAs methylation efficiency was determined based on relative concentrations of the As metabolites in urine (%MMA, %DMA, and %iAs). Thirty-two single nucleotide polymorphisms (SNPs) in nine genes were determined in maternal DNA; AS3MT haplotypes were inferred. We assessed the association between genotypes/haplotypes and maternal As methylation efficiency using multivariate linear regression models.

RESULTS

The median %MMA and %DMA were 5.3 %, and 89 %, respectively. Ancestral alleles of AS3MT SNPs (rs3740393, rs3740390, rs11191453, and rs11191454) were significantly associated with higher %MMA, %iAs, and lower %DMA. Pregnant participants with zero copies of the GGCTTCAC AS3MT haplotype presented a higher %MMA. Statistically significant associations were also found for the FOLH1 SNP rs202676 (β 0.89 95%CI: 0.24, 1.55 for carriers of the G allele vs. the A allele).

CONCLUSIONS

Our study shows that ancestral alleles in AS3MT polymorphisms were associated with lower As methylation efficiency in early pregnancy and suggests that FOLH1 also plays a role in As methylation efficiency. These results support the hypothesis that As metabolism is multigenic, being a key element for identifying susceptible populations.

Sleep problems at ages 8-9 and ADHD symptoms at ages 10-11: evidence in three cohorts from INMA study

Sleep problems and attention deficit hyperactivity disorder (ADHD) are interrelated during childhood and preadolescence. The objective of this work is assessing if sleep problems at ages 8-9 represent an alarm sign for presenting ADHD problems at ages 10-11 in three cohorts from INMA Study. Participants were 1244 children from Gipuzkoa, Sabadell, and Valencia cohorts. Sleep problems were assessed (ages 8-9) with the sleep items of the Child's Behaviour Checklist (CBCL), and ADHD problems were collected through the Conner's Parent Rating Scales-Revised: Short Form (CPRS-R:S) (age 10-11). Minimally and fully adjusted negative binomial models were fitted for each CPRS-R:S scale. Linearity of the relationship was assessed with generalized additive models (cubic smoothing splines with 2, 3, and 4 knots). For sensitivity analyses, children with previous symptoms, those born preterm and small for gestational age, and cases with extreme values, were excluded. Sleep problems presented IRR (95% CI) of 1.14 (1.10-1.19), 1.20 (1.14-1.26), 1.18 (1.11-1.25), and 1.18 (1.13-1.23) for opposition, inattention, hyperactivity, and ADHD scales, respectively. Fully adjusted models slightly decreased the IRR, but the association remained similar and significant. Sensitivity analyses showed similar results to fully adjusted models with only hyperactivity shown a slight decrease on significance (p = 0.051) when ADHD cases at age 9 were excluded.   Conclusion: Sleep problems are an alarm sign for later neurodevelopment problems such as ADHD. Healthcare systems could take advantage implementing policies to pay special attention on the sleep habits and sleep hygiene. This could contribute to add evidence to public health programmes such as the Healthy Child Programme.

Residential green and blue spaces and working memory in children aged 6-12 years old. Results from the INMA cohort

Availability of green and blue spaces in the area of residence has been related to various health outcomes during childhood, including neurodevelopment. Some studies have shown that children living in greener and/or bluer areas score better on cognitive tasks although the evidence is inconsistent. These protective effects are hypothesized to occur in part through reductions in air pollution exposure and odds of attention-deficit/hyperactivity disorder (ADHD). This study analysed the effects of residential green and blue spaces on working memory of children in the Spanish INfancia y Medio Ambiente (INMA) birth cohort and the potential joint mediating role of air pollution and ADHD. The study samples were composed of 1738 six-to eight-year-olds (M = 7.53, SD = 0.68, 49% female) and 1449 ten-to twelve-year-olds (M = 11.18, SD = 0.69, 50% female) living in Asturias, Gipuzkoa, Sabadell or Valencia, Spain. Individual Normalized Difference Vegetation Index (NDVI) values in 100-, 300- and 500-m buffers and availability of green and blue spaces >5000 m2 in 300-m buffers were calculated using Geographic Information Systems software. Individual NO2 values for the home environment were estimated using ESCAPE's land use regression models. ADHD diagnosis was reported by participants' parents via a questionnaire. Working memory was measured with numbers and colours (in the younger group only) N-back tests (2- and 3-back d'). Mixed-effects models informed of the beneficial effects of NDVI in a 300-m buffer on numerical working memory in the younger sample although the results were not consistent for all d' scores considered and failed to detect significant effects through the candidate mediators. Availability of major blue spaces did not predict working memory performance. Provision of green spaces may play a role in children's working memory but further research is required.

Maternal caffeine consumption during pregnancy and offspring cord blood DNA methylation: an epigenome-wide association study meta-analysis

Background: Prenatal caffeine exposure may influence offspring health via DNA methylation, but no large studies have tested this. Materials & methods: Epigenome-wide association studies and differentially methylated regions in cord blood (450k or EPIC Illumina arrays) were meta-analyzed across six European cohorts (n = 3725). Differential methylation related to self-reported caffeine intake (mg/day) from coffee, tea and cola was compared with assess whether caffeine is driving effects. Results: One CpG site (cg19370043, PRRX1) was associated with caffeine and another (cg14591243, STAG1) with cola intake. A total of 12-22 differentially methylated regions were detected with limited overlap across caffeinated beverages. Conclusion: We found little evidence to support an intrauterine effect of caffeine on offspring DNA methylation. Statistical power limitations may have impacted our findings.

Statistical Approaches to Study Exposome-Health Associations in the Context of Repeated Exposure Data: A Simulation Study

The exposome concept aims to consider all environmental stressors simultaneously. The dimension of the data and the correlation that may exist between exposures lead to various statistical challenges. Some methodological studies have provided insight regarding the efficiency of specific modeling approaches in the context of exposome data assessed once for each subject. However, few studies have considered the situation in which environmental exposures are assessed repeatedly. Here, we conduct a simulation study to compare the performance of statistical approaches to assess exposome-health associations in the context of multiple exposure variables. Different scenarios were tested, assuming different types and numbers of exposure-outcome causal relationships. An application study using real data collected within the INMA mother-child cohort (Spain) is also presented. In the simulation experiment, assessed methods showed varying performance across scenarios, making it challenging to recommend a one-size-fits-all strategy. Generally, methods such as sparse partial least-squares and the deletion-substitution-addition algorithm tended to outperform the other tested methods (ExWAS, Elastic-Net, DLNM, or sNPLS). Notably, as the number of true predictors increased, the performance of all methods declined. The absence of a clearly superior approach underscores the additional challenges posed by repeated exposome data, such as the presence of more complex correlation structures and interdependencies between variables, and highlights that careful consideration is essential when selecting the appropriate statistical method. In this regard, we provide recommendations based on the expected scenario. Given the heightened risk of reporting false positive or negative associations when applying these techniques to repeated exposome data, we advise interpreting the results with caution, particularly in compromised contexts such as those with a limited sample size.

Genetic Susceptibility to Neurotoxicity Related to Prenatal Inorganic Arsenic Exposure in Young Spanish Children

We explored the influence of child and maternal single nucleotide polymorphisms (SNPs) in genes related to neurological function and arsenic metabolism (i.e., ABCA1, ABCB1, PON1, CYP3A, BDNF, GSTP1, MT2A, and APOE as well as AS3MT) on the association between prenatal arsenic (As) exposure and methylation efficiency and neuropsychological development in 4-5-year-old children. Participants were 549 mother-child pairs from the INMA (Environment and Childhood) Spanish Project. We measured inorganic arsenic (iAs) and the metabolites monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) in urine samples collected during pregnancy. Neuropsychological development was assessed at the age of 4-5 years using the McCarthy Scales of Children's Abilities (MSCA). Several SNPs were determined in maternal and child DNA; AS3MT and APOE haplotypes were inferred. The median ∑As (sum of iAs, DMA, and MMA) was 7.08 μg/g creatinine. Statistically significant interactions for children's APOE haplotype were observed. Specifically, ε4-carrier children had consistently lower MSCA scores in several scales with increasing ∑As and MMA concentrations. These results provide evidence regarding the neurotoxic effects of early life exposure to As, observing that the APOE ε4 allele could make children more vulnerable to this exposure.

Association of maternal prenatal urinary fluoride levels with ADHD symptoms in childhood

BACKGROUND

Health concerns about the potential impact of exposure to fluoride via drinking water (DW) on neuropsychological development include behavioral outcomes such as ADHD.

OBJECTIVE

We aimed to examine the association between prenatal maternal urinary fluoride and symptoms associated with attention-deficit/hyperactivity disorder (ADHD) at the age of 8 and 11 years.

METHOD

Data from 255 to 236 mother-child pairs from the "Infancia y Medio Ambiente" (INMA) birth cohort (Gipuzkoa; Spain) with maternal urinary F adjusted for creatinine (MUFcr) during pregnancy (first and third trimester) and child assessments of ADHD-like symptoms reported by Conners' Rating Scales-Revised at age of 8 and 11 years was available. Clinical approach was also used: cut off criteria (T > 66). Multiple linear regression models were fitted when outcomes were analyzed as continuous, and logistic regression models when the outcomes were analyzed with a categorical clinical approach. Covariates related to maternal characteristics, birth outcomes, childhood, quality of family context and biomarkers of neuro-toxicants were used.

RESULTS

No association was found between MUFcr levels during pregnancy and cognitive problems-inattention, hyperactivity or ADHD index score of symptoms at 8 or 11 years. When results were analyzed from the perspective of a clinical approach, at the age of 11 years, there were significant inverse association between MUFcr and being categorized as a cognitive problems-inattention case. ORs were also indicative of a lower risk, although not significant, for ADHD index at age 11. Sensitivity analyses, taking into consideration quality of family context or the levels of other toxicants during pregnancy showed similar results.

CONCLUSIONS

Higher levels of MUFcr in pregnant women were associated with a lower risk of cognitive problems-inattention at 11 years. These findings are inconsistent with those from previous studies and indicate the need for other population-based studies to confirm or overturn these results.

Prenatal Exposure to Multiple Endocrine-Disrupting Chemicals and Childhood BMI Trajectories in the INMA Cohort Study

BACKGROUND

Prenatal exposure to endocrine-disrupting chemicals (EDCs) may disrupt normal fetal and postnatal growth. Studies have mainly focused on individual aspects of growth at specific time points using single chemical exposure models. However, humans are exposed to multiple EDCs simultaneously, and growth is a dynamic process.

OBJECTIVE

The objective of this study was to evaluate the associations between prenatal exposure to EDCs and children's body mass index (BMI) growth trajectories using single exposure and mixture modeling approaches.

METHODS

Using data from the INfancia y Medio Ambiente (INMA) Spanish birth cohort (n = 1,911 ), prenatal exposure to persistent chemicals [hexachlorobenzene (HCB), 4-4'-dichlorodiphenyldichloroethylene (DDE), polychlorinated biphenyls (PCB-138, -150, and -180), 4 perfluoroalkyl substances (PFAS)] and nonpersistent chemicals (8 phthalate metabolites, 7 phenols) was assessed using blood and spot urine concentrations. BMI growth trajectories were calculated from birth to 9 years of age using latent class growth analysis. Multinomial regression was used to assess associations for single exposures, and Bayesian weighted quantile sum (BWQS) regression was used to evaluate the EDC mixture's association with child growth trajectories.

RESULTS

In single exposure models exposure to HCB, DDE, PCBs, and perfluorononanoic acid (PFNA) were associated with increased risk of belonging to a trajectory of lower birth size followed by accelerated BMI gain by 19%-32%, compared with a trajectory of average birth size and subsequent slower BMI gain [e.g., relative risk ratio (RRR) per doubling in DDE concentration = 1.19 (95% CI: 1.05, 1.35); RRR for PFNA = 1.32 (95% CI: 1.05, 1.66)]. HCB and DDE exposure were also associated with higher probability of belonging to a trajectory of higher birth size and accelerated BMI gain. Results from the BWQS regression showed the mixture was positively associated with increased odds of belonging to a BMI trajectory of lower birth size and accelerated BMI gain (odds ratio per 1-quantile increase of the mixture = 1.70 ; credible interval: 1.03, 2.61), with HCB, DDE, and PCBs contributing the most.

DISCUSSION

This study provides evidence that prenatal EDC exposure, particularly persistent EDCs, may lead to BMI trajectories in childhood characterized by accelerated BMI gain. Given that accelerated growth is linked to a higher disease risk in later life, continued research is important. https://doi.org/10.1289/EHP11103.

Blood miRNA levels associated with ADHD traits in children across six European birth cohorts

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) is a prevalent and highly heritable neurodevelopmental disorder of major societal concern. Diagnosis can be challenging and there are large knowledge gaps regarding its etiology, though studies suggest an interplay of genetic and environmental factors involving epigenetic mechanisms. MicroRNAs (miRNAs) show promise as biomarkers of human pathology and novel therapies, and here we aimed to identify blood miRNAs associated with traits of ADHD as possible biomarker candidates and further explore their biological relevance.

METHODS

Our study population consisted of 1126 children (aged 5-12 years, 46% female) from the Human Early Life Exposome study, a study spanning six ongoing population-based European birth cohorts. Expression profiles of miRNAs in whole blood samples were quantified by microarray and tested for association with ADHD-related measures of behavior and neuropsychological functions from questionnaires (Conner's Rating Scale and Child Behavior Checklist) and computer-based tests (the N-back task and Attention Network Test).

RESULTS

We identified 29 miRNAs significantly associated (false discovery rate < .05) with the Conner's questionnaire-rated trait hyperactivity, 15 of which have been linked to ADHD in previous studies. Investigation into their biological relevance revealed involvement in several pathways related to neurodevelopment and function, as well as being linked with other neurodevelopmental or psychiatric disorders known to overlap with ADHD both in symptomology, genetic risk, and co-occurrence, such as autism spectrum disorder or schizophrenia. An additional three miRNAs were significantly associated with Conner's-rated inattention. No associations were found with questionnaire-rated total ADHD index or with computer-based tests.

CONCLUSIONS

The large overlap of our hyperactivity-associated miRNAs with previous studies on ADHD is intriguing and warrant further investigation. Though this study should be considered explorative and preliminary, these findings contribute towards identifying a set of miRNAs for use as blood-based biomarkers to aid in earlier and easier ADHD diagnosis.

Association between mediterranean diet and metal(loid) exposure in 4-5-year-old children living in Spain

Even relatively low levels of metals exposure may impact health, particularly among vulnerable populations such as infants and young children. However, little is known about the interplay between simultaneous metal exposures, common in real-life scenarios, and their association with specific dietary patterns. In this study, we have evaluated the association between adherence to Mediterranean diet (MD) and urinary metal concentrations individually and as an exposure mixture in 713 children aged 4-5-years from the INMA cohort study. We used a validated food frequency questionnaire to calculate two MD indexes scores: aMED and rMED. These indexes gather information on various food groups within the MD and score differently. To measure urinary concentrations of cobalt, copper, zinc, molybdenum, selenium, lead, and cadmium as exposure biomarkers, we used inductively coupled plasma mass spectrometry (ICP-MS), coupled with an ion chromatography (IC) equipment for arsenic speciation analysis. We applied linear regression and quantile g-computation, adjusted for confounders, to analyse the association between MD adherence and exposure to the metal mixture. High adherence to MD such as the quintile (Q) 5 MD was associated with higher urinary arsenobetaine (AsB) levels than Q1, with β values of 0.55 (confidence interval - CI 95% 0.01; 1.09) for aMED and 0.73 (CI 95% 0.13; 1.33) for rMED. Consumption of fish was associated with increased urinary AsB but reduced inorganic arsenic concentrations. In contrast, the aMED vegetables consumption increased urinary inorganic arsenic content. A moderate level of adherence to MD (Q2 and Q3) was associated with lower copper urinary concentrations than Q1, with β values of -0.42 (CI 95% -0.72; -0.11) for Q2 and -0.33 (CI 95% -0.63; -0.02) for Q3, but only with aMED. Our study, conducted in Spain, revealed that adhering to the MD reduces exposure to certain metals while increasing exposure to others. Specifically, we observed increase in exposure to non-toxic AsB, highlighting the significance of consuming fish/seafood. However, it is crucial to emphasize the necessity for additional efforts in reducing early-life exposure to toxic metals, even when adhering to certain food components of the MD.

Social inequalities, green and blue spaces and mental health in 6-12 years old children participating in the INMA cohort

Availability of green and blue spaces in the area of residence has been related to various health outcomes during childhood, including mental health. These environmental exposures are not evenly distributed among socioeconomic groups, which may increase social inequalities in mental health. The mechanisms through which natural environments may promote mental health are numerous and diverse. This study aimed to explore 1) the potential associations of socioeconomic variables (SES and maternal education attainment) with mental health scores and residential greenness, blueness and NO2 metrics, and, 2) the association between greenness and blueness metrics and mental health scores of children in the Spanish INfancia y Medio Ambiente (INMA) birth cohort at two different time points. The study samples were composed of 1738 six-to eight-year-olds (49% female) and 1449 ten-to twelve-year-olds (living in Asturias, Gipuzkoa, Sabadell and Valencia, Spain. Individual Normalized Difference Vegetation Index (NDVI) values in 100-, 300- and 500-m buffers and availability of green and blue spaces >5000 m2 in 300-m buffers were calculated using Geographic Information Systems software. Residential NO2 values were estimated using land use regression models. Internalizing, externalizing and total problems scores were obtained with the Strengths and Difficulties Questionnaire (SDQ). Linear and logistic mixed-effects models revealed unequal distribution of environmental exposures by SES and maternal education but did not show statistically significant associations between greenness and blueness metrics and mental health indicators. The protective effect of green and blue spaces on children's mental health could not be confirmed in this study and therefore further research is required.

Tracking between cardiovascular-related measures at 4 and 8 years of age in the INMA-Asturias cohort

Identifying cardiovascular-related measures that track from early childhood into later ages may help inform early prevention targets for cardiovascular disease. In this study, the tracking of triglycerides (TG), high-density cholesterol (HDL-c), atherogenic coefficient (AC), waist circumference to height ratio (WC/Height), mean arterial pressure (MAP), and homeostatic model assessment of insulin resistance (HOMA-IR) was examined in the INMA-Asturias cohort between 4 and 8 years of age. The analysis was conducted in 307 children who participated in the INMA-Asturias cohort (Spain) at 4 and at 8 years of age. Quantile regression models were used to evaluate tracking between measures at both ages, with each measure at 8 years as the dependent variable and the rank transformation of the same measure at 4 years as the independent variable. We found a positive association between HDL-c rank at 4 years and higher quantiles of the HDL-c distribution at 8 years, with an increase of 2.93 mg/dL (95% CI: 1.98, 3.87) per decile in the 0.9 quantile. A positive association was also found for WC/Height, with an increase of 0.008 (95% CI: 0.004, 0.012) per decile in the 0.9 quantile. We observed that tracking for AC increased in the higher quantiles of the distribution at 8 years, with an increase of 0.11 (95% CI: 0.09, 0.14) in the 0.6 quantile compared to an effect of 0.15 (95% CI: 0.09, 0.21) in the 0.9 quantile.  Conclusions: Adult markers of dyslipidemia and central obesity tracked between ages 4 and 8 years. For AC, tracking increased in the higher quantiles of the distribution. What is Known: • Atherosclerosis begins in early life, so preventive efforts that start in childhood may delay progression to clinical disease. Determine what cardiovascular risk factors track into time since childhood bring the opportunity to identified those subjects at risk for later cardiovascular disease. • The study of risk factors in health populations and, particularly in children, copes with not clear and/or controversial thresholds definition. This makes it challenging to study tracking in pediatric ages. What is New: • Quantile regression is a useful tool for assessing the tracking of risk factors for which there are no clinically meaningful thresholds. The increasing trend observed in the tracking of dyslipidemia suggests the possible difficulty that children with abnormal values at 4 years of age might have in normalizing them in future years. • The findings of this article may help to determine which cardiovascular-related measures could be screened and followed-up in children.

Exposure to mercury among Spanish adolescents: Eleven years of follow-up

The toxic effects of mercury exposure on human health are a public health concern. The most important source of this exposure is the consumption of fish and marine mammals. This study aims to describe hair mercury concentrations and their evolution from birth until eleven years of age in adolescents from the INMA (Environment and Childhood) birth cohort study, and to assess the association of hair mercury concentrations at eleven years of age with sociodemographic and dietary factors. The sample comprised 338 adolescents from the sub-cohort of Valencia (in eastern Spain). Total mercury (THg) was measured in hair samples collected at 4, 9 and 11 years old and in cord blood at birth. The equivalent of hair for cord-blood THg concentrations was calculated. Fish consumption and other characteristics at 11 years old were collected through questionnaires. Multivariate linear regression models were conducted to explore the association between THg concentrations, fish consumption and covariates. The geometric mean of hair THg concentrations at 11 years of age was 0.86 μg/g (95%CI: 0.78-0.94) and 45.2% of the participants presented concentrations above the equivalent RfD proposed by the US EPA (1 μg/g). Consumption of fish such as swordfish, canned tuna and other large oily fish was associated with higher levels of hair mercury at 11 years of age. Swordfish had the highest effect with an increase of 125% in hair mercury (95%CI: 61.2-214.9%) given a 100 g/week increase in its consumption, and, taking into account the frequency of consumption, canned tuna was the main contributor to Hg exposure among our population. The hair THg concentrations at 11 years of age represented a reduction of around 69% with respect to that estimated at childbirth. Even though THg exposure shows a sustained decreasing trend, it can still be considered elevated. INMA birth cohort studies provide a longitudinal assessment of mercury exposure in a vulnerable population, its associated factors and temporal trends, and this information could be used to adjust recommendations about this issue.

Distinction between rhinitis alone and rhinitis with asthma using interactomics

The concept of "one-airway-one-disease", coined over 20 years ago, may be an over-simplification of the links between allergic diseases. Genomic studies suggest that rhinitis alone and rhinitis with asthma are operated by distinct pathways. In this MeDALL (Mechanisms of the Development of Allergy) study, we leveraged the information of the human interactome to distinguish the molecular mechanisms associated with two phenotypes of allergic rhinitis: rhinitis alone and rhinitis in multimorbidity with asthma. We observed significant differences in the topology of the interactomes and in the pathways associated to each phenotype. In rhinitis alone, identified pathways included cell cycle, cytokine signalling, developmental biology, immune system, metabolism of proteins and signal transduction. In rhinitis and asthma multimorbidity, most pathways were related to signal transduction. The remaining few were related to cytokine signalling, immune system or developmental biology. Toll-like receptors and IL-17-mediated signalling were identified in rhinitis alone, while IL-33 was identified in rhinitis in multimorbidity. On the other hand, few pathways were associated with both phenotypes, most being associated with signal transduction pathways including estrogen-stimulated signalling. The only immune system pathway was FceRI-mediated MAPK activation. In conclusion, our findings suggest that rhinitis alone and rhinitis and asthma multimorbidity should be considered as two distinct diseases.

Prenatal exposure to multiple persistent organic pollutants in association with adiposity markers and blood pressure in preadolescents

BACKGROUND

Several studies have reported that prenatal exposure to some persistent organic pollutants (POPs) is associated with higher adiposity in childhood. Few studies have assessed whether this finding persists into adolescence, and few have considered exposure to POPs as a mixture. This study aims to assess the association between prenatal exposure to multiple POPs and adiposity markers and blood pressure in preadolescents.

METHODS

This study included 1667 mother-child pairs enrolled in the PELAGIE (France) and the INMA (Spain) mother-child cohorts. Three polychlorobiphenyls (PCB 138, 153 and 180, treated as a sum of PCBs) and three organochlorine pesticides (p,p'-Dichlorodiphenyldichloroethylene [p,p'-DDE], β-hexachlorocyclohexane [β-HCH], and hexachlorobenzene [HCB]) were assessed in maternal or cord serum. Body mass index z-score (zBMI), abdominal obesity (waist-to-height ratio > 0.5), percentage of fat mass, and blood pressure (mmHg) were measured at around 12 years of age. Single-exposure associations were studied using linear or logistic regressions, and the POP mixture effect was evaluated using quantile G-computation (qgComp) and Bayesian Kernel Machine Regression (BKMR). All models were adjusted for potential confounders and performed for boys and girls together and separately.

RESULTS

Prenatal exposure to the POP mixture was associated with higher zBMI (beta [95 % CI] of the qgComp = 0.15 [0.07; 0.24]) and percentage of fat mass (0.83 [0.31; 1.35]), with no evidence of sex-specific association. These mixture effects were also statistically significant using BKMR. These associations were driven mainly by exposure to HCB and, to a lesser extent, to β-HCH. In addition, the single-exposure models showed an association between β-HCH and p,p'-DDE and higher systolic blood pressure, especially in girls (p,p'-DDE for girls = 1.00 [0.15; 1.86]). No significant associations were found for PCBs.

CONCLUSION

This study suggests that prenatal exposure to POPs, particularly organochlorine pesticides, remains associated with unfavorable cardiometabolic health up to the age of 12.

Exploration of thyroglobulin as a biomarker of iodine status in iodine-sufficient and mildly iodine-deficient pregnant women

PURPOSE

Urinary iodine-to-creatinine ratio (UI/Creat) reflects recent iodine intake but has limitations for assessing habitual intake. Thyroglobulin (Tg) concentration, which increases with thyroid size, appears to be an indicator of longer-term iodine status in children and adults, however, less is known in pregnancy. This study investigated the determinants of serum-Tg in pregnancy and its use as an iodine-status biomarker in settings of iodine-sufficiency and mild-to-moderate deficiency.

METHODS

Stored blood samples and existing data from pregnant women from the Netherlands-based Generation R (iodine-sufficient) and the Spain-based INMA (mildly-to-moderately iodine-deficient) cohorts were used. Serum-Tg and iodine status (as spot-urine UI/Creat) were measured at median 13 gestational weeks. Using regression models, maternal socio-demographics, diet and iodine-supplement use were investigated as determinants of serum-Tg, as well as the association between UI/Creat and serum-Tg.

RESULTS

Median serum-Tg was 11.1 ng/ml in Generation R (n = 3548) and 11.5 ng/ml in INMA (n = 1168). When using 150 µg/g threshold for iodine deficiency, serum-Tg was higher in women with UI/Creat < 150 vs ≥ 150 µg/g (Generation R, 12.0 vs 10.4 ng/ml, P = 0.010; INMA, 12.8 vs 10.4 ng/ml, P < 0.001); after confounder adjustment, serum-Tg was still higher when UI/Creat < 150 µg/g (regression coefficients: Generation R, B = 0.111, P = 0.050; INMA, B = 0.157, P = 0.010). Iodine-supplement use and milk intake were negatively associated with serum-Tg, whereas smoking was positively associated.

CONCLUSION

The association between iodine status and serum-Tg was stronger in the iodine-deficient cohort, than in the iodine-sufficient cohort. Serum-Tg might be a complementary (to UI/Creat) biomarker of iodine status in pregnancy but further evidence is needed.

Environmental exposures in early-life and general health in childhood

BACKGROUND

Early-life environmental exposures are suspected to be involved in the development of chronic diseases later in life. Most studies conducted so far considered single or few exposures and single-health parameter. Our study aimed to identify a childhood general health score and assess its association with a wide range of pre- and post-natal environmental exposures.

METHODS

The analysis is based on 870 children (6-12 years) from six European birth cohorts participating in the Human Early-Life Exposome project. A total of 53 prenatal and 105 childhood environmental factors were considered, including lifestyle, social, urban and chemical exposures. We built a general health score by averaging three sub-scores (cardiometabolic, respiratory/allergy and mental) built from 15 health parameters. By construct, a child with a low score has a low general health status. Penalized multivariable regression through Least Absolute Shrinkage and Selection Operator (LASSO) was fitted in order to identify exposures associated with the general health score.

FINDINGS

The results of LASSO show that a lower general health score was associated with maternal passive and active smoking during pregnancy and postnatal exposure to methylparaben, copper, indoor air pollutants, high intake of caffeinated drinks and few contacts with friends and family. Higher child's general health score was associated with prenatal exposure to a bluespace near residency and postnatal exposures to pets, cobalt, high intakes of vegetables and more physical activity. Against our hypotheses, postnatal exposure to organochlorine compounds and perfluorooctanoate were associated with a higher child's general health score.

CONCLUSION

By using a general health score summarizing the child cardiometabolic, respiratory/allergy and mental health, this study reinforced previously suspected environmental factors associated with various child health parameters (e.g. tobacco, air pollutants) and identified new factors (e.g. pets, bluespace) warranting further investigations.

Exposure to perfluoroalkyl substances (PFAS) and association with thyroid hormones in adolescent males

BACKGROUND

Perfluoroalkyl substances (PFAS) are found in a wide range of consumer products. Exposure to PFAS in children and adolescents may be associated with alterations in thyroid hormones, which have critical roles in brain function.

OBJECTIVE

This study investigated the association between plasma concentrations of PFAS and serum levels of total triiodothyronine (T3), free thyroxine (T4), and thyroid-stimulating hormone (TSH) in adolescent males.

METHODS

In 2017-2019, 151 boys from the Environment and Childhood (INMA)-Granada birth cohort, Spain, participated in a clinical follow up visit at the age of 15-17 years. Plasma concentrations of ten PFAS (PFHxA, PFHpA, PFOA, PFNA, PFDA, PFUnDA, PFDoDA, PFTrDA, PFOS, and PFHxS) and serum thyroid hormones were measured in 129 of these boys. Linear regression analysis was performed to determine associations of individual PFAS with total T3, free T4, TSH, and free T4/TSH ratio, and quantile g-computation models were performed to assess the mixture effect. Additional models considered iodine status as effect modifier.

RESULTS

PFOS was the most abundant PFAS in plasma (median = 2.22 μg/L), followed by PFOA (median = 1.00 μg/L), PFNA (median = 0.41 μg/L), and PFHxS (median = 0.40 μg/L). When adjusted by confounders (including age, maternal schooling, and fish intake), PFOA and PFUnDA were associated with an increase in free T4 (β [95% CI] = 0.72 [0.06; 1.38] and 0.36 [0.04; 0.68] pmol/L, respectively, per two-fold increase in plasma concentrations), with no change in TSH. PFOS, the sum of PFOA, PFNA, PFOS, and PFHxS, and the sum of long-chain PFAS were marginally associated with increases in free T4. Associations with higher free T4 and/or total T3 were seen for several PFAS in boys with lower iodine intake (<108 μ/day) alone. Moreover, the PFAS mixture was association with an increase in free T4 levels in boys with lower iodine intake (% change [95% CI] = 6.47 [-0.69; 14.11] per each quartile increase in the mixture concentration).

CONCLUSIONS

Exposure to PFAS, considered individually or as a mixture, was associated with an increase in free T4 levels in boys with lower iodine intake. However, given the small sample size, the extent of these alterations remains uncertain.

Mediators of the association between maternal body mass index and breastfeeding duration in 3 international cohorts

BACKGROUND

Maternal obesity has been associated with shorter breastfeeding duration, but little is known about mediating factors explaining this association. It is important to assess these relationships across diverse populations because breastfeeding is culturally patterned.

OBJECTIVES

We investigated the association of prepregnancy maternal body mass index (BMI) with breastfeeding outcomes and potential mediators of this relationship in 3 culturally diverse international cohorts.

METHODS

We analyzed 5120 singleton pregnancies from mother-child cohorts in Spain (INfancia y Medio Ambiente), Greece (Rhea), and the United States (Project Viva). Outcome variables were duration of any and exclusive breastfeeding. A priori hypothesized mediators in the association of maternal prepregnancy BMI with breastfeeding were birthweight (BW), maternal prenatal C-reactive protein (CRP), cesarean delivery, maternal dietary inflammatory index (DII) during pregnancy, gestational age at delivery, and gestational diabetes mellitus (GDM). We estimated the association between BMI and breastfeeding duration using linear regression adjusting for confounders. Mediation analysis estimated direct and indirect effects of maternal overweight/obesity on breastfeeding for each mediator.

RESULTS

Women with overweight and obesity had shorter duration of any and exclusive breastfeeding compared with normal-weight women (any: overweight β = -0.79 mo, 95% CI: -1.17, -0.40; obese β = -1.75 mo 95% CI: -2.25, -1.25; exclusive: overweight β = -0.30 mo, 95% CI: -0.42, -0.16; obese β = -0.73 mo, 95% CI: -0.90, -0.55). Significant mediators (% change in effect estimate) of this association were higher CRP (exclusive: 5.12%), cesarean delivery (any: 6.54%; exclusive: 7.69%), and higher DII (any: 6.48%; exclusive: 7.69%). GDM, gestational age, and BW did not mediate the association of maternal weight status with breastfeeding.

CONCLUSIONS

Higher prepregnancy BMI is associated with shorter duration of any and exclusive breastfeeding. Maternal dietary inflammation, systemic inflammation, and mode of delivery may be key modifiable mediators of this association. Identification of mediators provides potential targets for interventions to improve breastfeeding outcomes.