Exposure of pregnant women to organophosphate insecticides and child motor inhibition at the age of 10-12 years evaluated by fMRI

Exploring the link between the pediatric exposome, respiratory health, and executive function in children: a narrative review

Asthma is a highly prevalent inflammatory condition, significantly affecting nearly six million U.S. children and impacting various facets of their developmental trajectories including neurodevelopment. Evidence supports a link between pediatric environmental exposures in two key areas: asthma and executive function (E.F.). E.F.s are a collective of higher-order cognitive processes facilitating goal-oriented behaviors. Studies also identify asthma-associated E.F. impairments in children. However, limited research has evaluated the inter-relationships among environmental exposures, asthma, and E.F. in children. This review explored relevant research to identify and connect the potential mechanisms and pathways underlying these dynamic associations. The review suggests that the role of the pediatric exposome may function through (1) several underlying biological pathways (i.e., the lung-brain axis, neuroendocrine system, and hypoxia), which could drive asthma and maladaptive E.F. in children and (2) the relationships between the exposome, asthma, and E.F. is a bidirectional linkage. The review reveals essential synergistic links between asthma and E.F. deficits, highlighting the potential role of the pediatric exposome.

The impact of psychosocial adversity on brain and behaviour: an overview of existing knowledge and directions for future research

Environmental experiences play a critical role in shaping the structure and function of the brain. Its plasticity in response to different external stimuli has been the focus of research efforts for decades. In this review, we explore the effects of adversity on brain's structure and function and its implications for brain development, adaptation, and the emergence of mental health disorders. We are focusing on adverse events that emerge from the immediate surroundings of an individual, i.e., microenvironment. They include childhood maltreatment, peer victimisation, social isolation, affective loss, domestic conflict, and poverty. We also take into consideration exposure to environmental toxins. Converging evidence suggests that different types of adversity may share common underlying mechanisms while also exhibiting unique pathways. However, they are often studied in isolation, limiting our understanding of their combined effects and the interconnected nature of their impact. The integration of large, deep-phenotyping datasets and collaborative efforts can provide sufficient power to analyse high dimensional environmental profiles and advance the systematic mapping of neuronal mechanisms. This review provides a background for future research, highlighting the importance of understanding the cumulative impact of various adversities, through data-driven approaches and integrative multimodal analysis techniques.

Exposure to Endocrine Disruptors in Early life and Neuroimaging Findings in Childhood and Adolescence: a Scoping Review

PURPOSE OF REVIEW: Evidence suggests neurotoxicity of endocrine disrupting chemicals (EDCs) during sensitive periods of development. We present an overview of pediatric population neuroimaging studies that examined brain influences of EDC exposure during prenatal period and childhood. RECENT FINDINGS: We found 46 studies that used magnetic resonance imaging (MRI) to examine brain influences of EDCs. These studies showed associations of prenatal exposure to phthalates, organophosphate pesticides (OPs), polyaromatic hydrocarbons and persistent organic pollutants with global and regional brain structural alterations. Few studies suggested alteration in functional MRI associated with prenatal OP exposure. However, studies on other groups of EDCs, such as bisphenols, and those that examined childhood exposure were less conclusive. These findings underscore the potential profound and lasting effects of prenatal EDC exposure on brain development, emphasizing the need for better regulation and strategies to reduce exposure and mitigate impacts. More studies are needed to examine the influence of postnatal exposure to EDC on brain imaging.

Biomonitoring of pesticide exposure and its health implications in agricultural areas of Telangana, India: A brief data report

The dataset represent the results of a cross-sectional study conducted in Telangana, India, to investigate the effects of pesticide exposure in agricultural regions. This study includes 341 pesticides exposed participants and 152 controls in three districts of Telangana including 15 farming villages. Blood and urine samples were analysed to determine various pesticide concentrations present in blood including organophosphates, carbamates and pyrethroids group of pesticides, and six dialkyl phosphate (DAP) metabolites, including dimethyl phosphate (DMP), diethyl phosphate (DEP), dimethyl thiophosphate (DMTP), dimethyldithiophosphate (DMDTP), diethylthiophosphate (DETP) and diethyldithiophosphate (DEDTP) were analysed in urine samples.In addition the enzyme acetylcholinesterase (AChE) activity were measured using advanced analytical methods. The data provide information on pesticide profiles, exposure biomarkers and the relationship between exposure duration and AChE activity. These study results emphasise the importance and addressing pesticide-related health problems in farmers for proactive measures to mitigate the harmful effects of pesticide exposure in agriculture.

Chronic exposures to cholinesterase-inhibiting pesticides adversely affects the health of agricultural workers in India

Biomonitoring of pesticide exposure has become a public concern because of its potential health effects. The present study investigated the acetylcholinesterase (AChE) inhibitory levels and their associated health effects in agricultural areas in Telangana, India. This cross-sectional included 341 exposed participants and 152 control participants from agricultural areas. A structured questionnaire was completed and blood and urine samples were collected to measure pesticides, dialkyle phosphate (DAP) metabolites, and AChE activity using liquid chromatography-tandem mass spectrometry and reversed-phase high-performance liquid chromatography. twenty-eight pesticides were detected in blood samples at concentrations ranging 0.42-45.77 ng/mL. Six DAP metabolites were also measured in urine, and all DAP metabolites were significantly higher in the exposed group. AChE activity is significantly reduced in individuals exposed for >10 years, raising concerns regarding possible neurological disorders. These results emphasise the urgent need to investigate the health effects of pesticides exposure, especially in agriculture.

Predictors of executive function among 2 year olds from a Thai birth cohort

Executive function (EF) is a critical skill for academic achievement. Research on the psychosocial and environmental predictors of EF, particularly among Southeast Asian, agricultural, and low income/rural populations, is limited. Our longitudinal study explored the influence of agricultural environmental, psychosocial, and temperamental factors on children's emerging EF. Three-hundred and nine farm worker women were recruited during the first trimester of pregnancy. We evaluated the effects of prenatal insecticide exposure and psychosocial factors on "cool" (i.e., cognitive: A-not-B task, looking version) and "hot" EF (i.e., affective, response inhibition) measures of emerging EF. Maternal urine samples were collected monthly during pregnancy, composited, and analyzed for dialkylphosphate (DAP) metabolites of organophosphate insecticides. Psychosocial factors included socioeconomic status, maternal psychological factors, and quality of mother-child behavioral interactions. Backward stepwise regressions evaluated predictors of children's EF at 12 (N = 288), 18 (N = 277) and 24 (N = 280) months of age. We observed different predictive models for cool EF, as measured by A-not-B task, vs. hot EF, as measured by response inhibition tasks. Report of housing quality as a surrogate for income was a significant predictor of emerging EF. However, these variables had opposite effects for cool vs. hot EF. More financial resources predicted better cool EF performance but poorer hot EF performance. Qualitative findings indicate that homes with fewer resources were in tribal areas where children must remain close to an adult for safety reasons. This finding suggests that challenging physical environments (e.g., an elevated bamboo home with no electricity or running water), may contribute to development of higher levels of response inhibition through parental socialization methods that emphasize compliance. Children who tended to show more arousal and excitability, and joy reactivity as young infants in the laboratory setting had better cognitive performance. In contrast, maternal emotional availability was a significant predictor of hot EF. As expected, increased maternal exposure to pesticides during pregnancy was associated with worse cognitive performance but was not associated with inhibitory control. Identifying risk factors contributing to the differential developmental pathways of cool and hot EF will inform prevention strategies to promote healthy development in this and other unstudied rural, low income Southeast Asian farming communities.

Urinary dialkylphosphate metabolites in the assessment of exposure to organophosphate pesticides: from 2000 to 2022

The general population and workers are exposed to organophosphate insecticides, one of the leading chemical classes of pesticides used in rural and urban areas, in the control of arboviruses and agriculture. These pesticides cause environmental/occupational exposure and associated risks to human and environmental health. The objective of this study was to carry out an integrative review of epidemiological studies that identified and quantified dialkylphosphate metabolites in the urine of exposed populations, focusing on the vector control workers, discussing the application and the results found. Searches utilized the Pubmed, Scielo, and the Brazilian Digital Library of Theses and Dissertations (BDTD) databases between 2000 and 2021. From the 194 selected studies, 75 (39%) were with children/adolescents, 48 (24%) with rural workers, 36 (19%) with the general population, 27 (14%) with pregnant women, and 9 (4%) with vector control workers. The total dialkylphosphate concentrations found in the occupationally exposed population were higher than in the general population. Studies demonstrate that dialkylphosphates are sensitive and representative exposure biomarkers for environmental and occupational organophosphate exposure. The work revealed a lack of studies with vector control workers and a lack of studies in developing countries.

Neuroanatomical differences in Latinx children from rural farmworker families and urban non-farmworker families and related associations with pesticide exposure

Exposure to pesticides in humans may lead to changes in brain structure and function and increase the likelihood of experiencing neurodevelopmental disorders. Despite the potential risks, there is limited neuroimaging research on the effects of pesticide exposure on children, particularly during the critical period of brain development. Here we used voxel-based morphometry (VBM) and diffusion tensor imaging (DTI) from magnetic resonance images (MRI) to investigate neuroanatomical differences between Latinx children (n = 71) from rural, farmworker families (FW; n = 48) and urban, non-farmworker families (NFW; n = 23). Data presented here serves as a baseline for our ongoing study examining the longitudinal effects of living in a rural environment on neurodevelopment and cognition in children. The VBM analysis revealed that NFW children had higher volume in several distinct regions of white matter compared to FW children. Tract-based spatial statistics (TBSS) of DTI data also indicated NFW children had higher fractional anisotropy (FA) in several key white matter tracts. Although the difference was not as pronounced as white matter, the VBM analysis also found higher gray matter volume in selected regions of the frontal lobe in NFW children. Notably, white matter and gray matter findings demonstrated a high degree of overlap in the medial frontal lobe, a brain region predominantly linked to decision-making, error processing, and attention functions. To gain further insights into the underlying causes of the observed differences in brain structure between the two groups, we examined the association of organochlorine (OC) and organophosphate (OP) exposure collected from passive dosimeter wristbands with brain structure. Based on our previous findings within this data set, demonstrating higher OC exposure in children from non-farmworker families, we hypothesized OC might play a critical role in structural differences between NFW and FW children. We discovered a significant positive correlation between the number of types of OC exposure and the structure of white matter. The regions with significant association with OC exposure were in agreement with the findings from the FW-NFW groups comparison analysis. In contrast, OPs did not have a statistically significant association with brain structure. This study is among the first multimodal neuroimaging studies examining the brain structure of children exposed to agricultural pesticides, specifically OC. These findings suggest OC pesticide exposure may disrupt normal brain development in children, highlighting the need for further neuroimaging studies within this vulnerable population.

Association of Prenatal Exposure to Organophosphate, Pyrethroid, and Neonicotinoid Insecticides with Child Neurodevelopment at 2 Years of Age: A Prospective Cohort Study

BACKGROUND

Widespread insecticide exposure might be a risk factor for neurodevelopment of our children, but few studies examined the mixture effect of maternal coexposure to organophosphate insecticides (OPPs), pyrethroids (PYRs), and neonicotinoid insecticides (NNIs) during pregnancy on child neurodevelopment, and critical windows of exposure are unknown.

OBJECTIVES

We aimed to evaluate the association of prenatal exposure to multiple insecticides with children's neurodevelopment and to identify critical windows of the exposure.

METHODS

Pregnant women were recruited into a prospective birth cohort study in Wuhan, China, from 2014-2017. Eight metabolites of OPPs (mOPPs), three metabolites of PYRs (mPYRs), and nine metabolites of NNIs (mNNIs) were measured in 3,123 urine samples collected at their first, second, and third trimesters. Children's neurodevelopment [mental development index (MDI) and psychomotor development index (PDI)] was assessed using the Bayley Scales of Infant Development at 2 years of age (N = 1,041 ). Multivariate linear regression models, generalized estimating equation models, and weighted quantile sum (WQS) regression were used to estimate the association between the insecticide metabolites and Bayley scores. Potential sex-specific associations were also examined.

RESULTS

Single chemical analysis suggested higher urinary concentrations of some insecticide metabolites at the first trimester were significantly associated with lower MDI and PDI scores, and the associations were more prominent among boys. Each 1-unit increase in ln-transformed urinary concentrations of two mOPPs, 3,5,6-trichloro-2-pyridinol and 4-nitrophenol, was associated with a decrease of 3.16 points [95% confidence interval (CI): - 5.59 , - 0.74 ] and 3.06 points (95% CI: - 5.45 , - 0.68 ) respectively in boys' MDI scores. Each 1-unit increase in that of trans-3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylic acid (trans-DCCA; an mPYR) was significantly associated with a decrease of 2.24 points (95% CI: - 3.89 , - 0.58 ) in boys' MDI scores and 1.90 points (95% CI: - 3.16 , - 0.64 ) in boys' PDI scores, respectively. Significantly positive associations of maternal urinary biomarker concentrations [e.g., dimethyl phosphate (a nonspecific mOPP) and desmethyl-clothianidin (a relatively specific mNNI)] with child neurodevelopment were also observed. Using repeated holdout validation, a 1-quartile increase in the WQS index of the insecticide mixture (in the negative direction) at the first trimester was significantly associated with a decrease of 3.02 points (95% CI: - 5.47 , - 0.57 ) in MDI scores among the boys, and trans-DCCA contributed the most to the association (18%).

CONCLUSIONS

Prenatal exposure to higher levels of certain insecticides and their mixture were associated with lower Bayley scores in children, particularly in boys. Early pregnancy may be a sensitive window for such an effect. Future studies are needed to confirm our findings. https://doi.org/10.1289/EHP12097.

Toxicant exposure and the developing brain: A systematic review of the structural and functional MRI literature

Youth worldwide are regularly exposed to pollutants and chemicals (i.e., toxicants) that may interfere with healthy brain development, and a surge in MRI research has begun to characterize the neurobiological consequences of these exposures. Here, a systematic review following PRISMA guidelines was conducted on developmental MRI studies of toxicants with known or suspected neurobiological impact. Associations were reviewed for 9 toxicant classes, including metals, air pollution, and flame retardants. Of 1264 identified studies, 46 met inclusion criteria. Qualitative synthesis revealed that most studies: (1) investigated air pollutants or metals, (2) assessed exposures prenatally, (3) assessed the brain in late middle childhood, (4) took place in North America or Western Europe, (5) drew samples from existing cohort studies, and (6) have been published since 2017. Given substantial heterogeneity in MRI measures, toxicant measures, and age groups assessed, more research is needed on all toxicants reviewed here. Future studies should also include larger samples, employ personal exposure monitoring, study independent samples in diverse world regions, and assess toxicant mixtures.

Organophosphorus Pesticide Exposure at 17 Weeks' Gestation and Odds of Offspring Attention-Deficit/Hyperactivity Disorder Diagnosis in the Norwegian Mother, Father, and Child Cohort Study

Prenatal organophosphorus pesticides (OPs) are ubiquitous and have been linked to adverse neurodevelopmental outcomes. However, few studies have examined prenatal OPs in relation to diagnosed attention-deficit/hyperactivity disorder (ADHD), with only two studies exploring this relationship in a population primarily exposed through diet. In this study, we used a nested case-control study to evaluate prenatal OP exposure and ADHD diagnosis in the Norwegian Mother, Father, and Child Cohort Study (MoBa). For births that occurred between 2003 and 2008, ADHD diagnoses were obtained from linkage of MoBa participants with the Norwegian Patient Registry (N = 297), and a reference population was randomly selected from the eligible population (N = 552). Maternal urine samples were collected at 17 weeks' gestation and molar sums of diethyl phosphates (ΣDEP) and dimethyl phosphates metabolites (ΣDMP) were calculated. Multivariable adjusted logistic regression models were used to estimate the association between prenatal OP metabolite exposure and child ADHD diagnosis. Additionally, multiplicative effect measure modification (EMM) by child sex was assessed. In most cases, mothers in the second and third tertiles of ΣDMP and ΣDEP exposure had slightly lower odds of having a child with ADHD, although confidence intervals were wide and included the null. EMM by child sex was not observed for either ΣDMP or ΣDEP. In summary, we did not find evidence that OPs at 17 weeks' gestation increased the odds of ADHD in this nested case-control study of ADHD in MoBa, a population primarily experiencing dietary exposure.

Pesticide exposure and cortical brain activation among farmworkers in Costa Rica

BACKGROUND

Previous epidemiological studies have reported associations of pesticide exposure with poor cognitive function and behavioral problems. However, these findings have relied primarily on neuropsychological assessments. Questions remain about the neurobiological effects of pesticide exposure, specifically where in the brain pesticides exert their effects and whether compensatory mechanisms in the brain may have masked pesticide-related associations in studies that relied purely on neuropsychological measures.

METHODS

We conducted a functional neuroimaging study in 48 farmworkers from Zarcero County, Costa Rica, in 2016. We measured concentrations of 13 insecticide, fungicide, or herbicide metabolites or parent compounds in urine samples collected during two study visits (approximately 3-5 weeks apart). We assessed cortical brain activation in the prefrontal cortex during tasks of working memory, attention, and cognitive flexibility using functional near-infrared spectroscopy (fNIRS). We estimated associations of pesticide exposure with cortical brain activation using multivariable linear regression models adjusted for age and education level.

RESULTS

We found that higher concentrations of insecticide metabolites were associated with reduced activation in the prefrontal cortex during a working memory task. For example, 3,5,6-trichloro-2-pyridinol (TCPy; a metabolite of the organophosphate chlorpyrifos) was associated with reduced activation in the left dorsolateral prefrontal cortex (β = -2.3; 95% CI: -3.9, -0.7 per two-fold increase in TCPy). Similarly, 3-phenoxybenzoic acid (3-PBA; a metabolite of pyrethroid insecticides) was associated with bilateral reduced activation in the dorsolateral prefrontal cortices (β = -3.1; 95% CI: -5.0, -1.2 and -2.3; 95% CI: -4.5, -0.2 per two-fold increase in 3-PBA for left and right cortices, respectively). These associations were similar, though weaker, for the attention and cognitive flexibility tasks. We observed null associations of fungicide and herbicide biomarker concentrations with cortical brain activation during the three tasks that were administered.

CONCLUSION

Our findings suggest that organophosphate and pyrethroid insecticides may impact cortical brain activation in the prefrontal cortex - neural dynamics that could potentially underlie previously reported associations with cognitive and behavioral function. Furthermore, our study demonstrates the feasibility and utility of fNIRS in epidemiological field studies.

Urinary para-nitrophenol levels of pregnant women and cognitive and motor function of their children aged 2 years: Evidence from the SMBCS (China)

BACKGROUND

Urinary para-nitrophenol (PNP), an exposure biomarker of ethyl parathion (EP) and methyl parathion (MP) pesticides, was still pervasively detected in the general population even after global restriction for years. And the concern whether there is an association of PNP level with child development of the nervous system is increasing. The current study aimed to evaluate the maternal urinary PNP concentrations during late pregnancy and the associations of PNP levels with cognitive and motor function of their children at the age of 2 years.

METHODS

323 mother-child pairs from the Sheyang Mini Birth Cohort Study were included in the current study. Gas chromatography-tandem mass spectrometry was used to measure concentrations of PNP, the specific metabolite of EP and MP, in maternal urine samples during pregnancy. Developmental quotients (DQs) scores measured with Gesell Developmental Scales were employed to evaluate cognitive and motor function of children aged 2 years. Generalized linear models were performed to analyze the associations of PNP concentrations in pregnant women's urine samples with cognitive and motor function of their children.

RESULTS

Maternal PNP was detected in all urine samples with a median of 4.11 μg/L and a range from 0.57 μg/L to 109.13 μg/L, respectively. Maternal urinary PNP concentrations showed a negative trend with DQ of motor area [regression coefficient (β) = - 1.35; 95 % confidence interval (95 %CI): - 2.37, - 0.33; P < 0.01], and the children whose mothers were in the fourth quartile exposure group performed significantly worse compared to the reference group (β = - 1.11; 95 %CI: - 1.80, - 0.42; P < 0.01). As for average DQ score, children with their mothers' urinary PNP concentrations in the third quartile group had higher scores than those in the first quartile group (β = 0.39; 95 %CI: 0.03, 0.75; P = 0.04). In sex-stratified analyses, a negative trend between maternal urinary PNP concentrations and DQ scores in motor area of children was only observed in boys (β = - 1.62; 95 %CI: - 2.80, - 0.43; P < 0.01). Boys in the third quartile group had higher DQ average scores than those in the lowest quartile as reference (β = 0.53; 95 %CI: 0.02, 1.04; P = 0.04).

CONCLUSIONS

The mothers from SMBCS may be widely exposed to EP and/or MP, which were associated with the cognitive and motor function of their children aged 2 years in a sex-specific manner. Our results might provide epidemiology evidence on the potential effects of prenatal exposure to EP and/or MP on children's cognitive and motor function.

Prenatal organophosphorus pesticide exposure and executive function in preschool-aged children in the Norwegian Mother, Father and Child Cohort Study (MoBa)

INTRODUCTION

Prenatal exposure to organophosphorus pesticides (OPPs) has been associated with neurodevelopmental deficits in children, however evidence linking OPPs with specific cognitive mechanisms, such as executive function (EF), is limited.

OBJECTIVE

This study aims to evaluate the association between prenatal exposure to OPPs with multiple measures of EF in preschool-aged children, while considering the role of variant alleles in OPP metabolism genes.

METHODS

We included 262 children with preschool attention-deficit/hyperactivity disorder (ADHD), and 78 typically developing children, from the Preschool ADHD substudy of the Norwegian, Mother, Father, and Child Cohort Study. Participants who gave birth between 2004 and 2008 were invited to participate in an on-site clinical assessment when the child was approximately 3.5 years; measurements of EF included parent and teacher rating on Behavior Rating Inventory of Executive Function-Preschool (BRIEF-P), and three performance-based assessments. We measured OPP metabolites in maternal urines collected at ∼17 weeks' gestation to calculate total dimethyl- (ΣDMP) and diethyl phosphate (ΣDEP) metabolite concentrations. We estimated multivariable adjusted β's and 95% confidence intervals (CIs) corresponding to a change in z-score per unit increase in log-ΣDMP/DEP. We further characterized gene-OPP interactions for maternal variants in PON1 (Q192R, M55L), CYP1A2 (1548T > C), CYP1A1 (IntG > A) and CYP2A6 (-47A > C).

RESULTS

Prenatal OPP metabolite concentrations were associated with worse parent and teacher ratings of emotional control, inhibition, and working memory. A one log-∑DMP increase was associated with poorer teacher ratings of EF on the BRIEF-P (e.g. emotional control domain: β = 0.55, 95% CI: 0.35, 0.74), when weighted to account for sampling procedures. We found less consistent associations with performance-based EF assessments. We found some evidence of modification for PON1 Q192R and CYP2A6 -47A > C. Association with other variants were inconsistent.

CONCLUSIONS

Biomarkers of prenatal OPP exposure were associated with more adverse teacher and parent ratings of EF in preschool-aged children.

Prenatal exposure to organophosphate pesticides and autism spectrum disorders in 11-year-old children in the French PELAGIE cohort

BACKGROUND

Organophosphate (OP) pesticides act by inhibiting acetylcholinesterase activity at synaptic junctions and have already been linked with deleterious effects on neurodevelopment, including autism spectrum disorders (ASD).

OBJECTIVES

To investigate the association of prenatal exposure to OP pesticides with traits related to ASD in 11-year-old children.

METHODS

The "Childhood Autism Spectrum Test" (CAST) parent questionnaire was used to screen for autistic traits in 792 children from the French PELAGIE cohort. Prenatal maternal urine samples were collected <19 weeks of gestation in which metabolites of organophosphate insecticides were assessed for 185 of them. Negative binomial regression models were performed to explore the association between the CAST score and 8 groups of urine components, adjusted for potential ASD risk factors.

RESULTS

In these urine samples, dialkylphosphates (DAP) were detected most often (>80%), terbufos and its metabolites least often (<10%). No association with ASD was found for DAP, terbufos or its metabolites. Incidence rate ratios (IRRs) increased with maternal urinary diazinon concentrations, from 1.11 (95% CI: 0.87-1.42) to 1.17 (95% CI: 0.94-1.46). Higher CAST scores were statistically significantly associated with the maternal urine samples in which chlorpyrifos or two of its metabolites (chlorpyrifos-oxon and 3,5,6-trichloro-2-pyridinol) were detected. The IRR for exposure to chlorpyrifos or chlorpyrifos-oxon was 1.27 (95%CI: 1.05-1.52) among all children, and 1.39 (95%CI: 1.07-1.82) among boys.

CONCLUSION

These findings suggest an increase in autistic traits among 11-year-old children in association with prenatal maternal exposure to chlorpyrifos and possibly diazinon. These associations were previously suspected in the literature, in particular for chlorpyrifos. Further work establishing the causal mechanisms behind these risk association is needed.

Altered Default Mode Network Associated with Pesticide Exposure in Latinx Children from Rural Farmworker Families

Pesticide exposure has been associated with adverse cognitive and neurological effects. However, neuroimaging studies aimed at examining the impacts of pesticide exposure on brain networks underlying abnormal neurodevelopment in children remain limited. It has been demonstrated that pesticide exposure in children is associated with disrupted brain anatomy in regions that make up the default mode network (DMN), a subnetwork engaged across a diverse set of cognitive processes, particularly higher-order cognitive tasks. This study tested the hypothesis that functional brain network connectivity/topology in Latinx children from rural farmworker families (FW children) would differ from urban Latinx children from non-farmworker families (NFW children). We also tested the hypothesis that probable historic childhood exposure to pesticides among FW children would be associated with network connectivity/topology in a manner that parallels differences between FW and NFW children. We used brain networks from functional magnetic resonance imaging (fMRI) data from 78 children and a mixed-effects regression framework to test our hypotheses. We found that network topology was differently associated with the connection probability between FW and NFW children in the DMN. Our results also indicated that, among 48 FW children, historic reports of exposure to pesticides from prenatal to 96 months old were significantly associated with DMN topology, as hypothesized. Although the cause of the differences in brain networks between FW and NFW children cannot be determined using a cross-sectional study design, the observed associations between network connectivity/topology and historic exposure reports in FW children provide compelling evidence for a contribution of pesticide exposure on altering the DMN network organization in this vulnerable population. Although longitudinal follow-up of the children is necessary to further elucidate the cause and reveal the ultimate neurological implications, these findings raise serious concerns about the potential adverse health consequences from developmental neurotoxicity associated with pesticide exposure in this vulnerable population.

Association between urinary dialkylphosphate metabolites and dyslexia among children from three cities of China: The READ program

Exposure to organophosphate (OP) insecticides has been found to be related to neurodevelopmental disorders in children. However, no study has examined the association between OP insecticide exposure and the risk of dyslexia among children. We aimed to explore the association between OP insecticide exposure, indicated by urinary dialkylphosphate metabolites (DAPs), and the risk of dyslexia among Chinese Han children from three cities. A total of 845 children (422 dyslexics and 423 non-dyslexics) from Tongji Reading Environment and Dyslexia research program were included in the current case-control study. We measured six DAPs in urine samples, collected from November 2017 to December 2020. Logistic regression models were used to estimate odds ratios (ORs) for the association between DAPs and dyslexia risk, adjusting for potential confounders. The detection frequencies of DAPs were above 97.5%, except for diethyldithiophosphate and dimethyldithiophosphate. Diethyl phosphate metabolites (DEs) were significantly associated with the risk of dyslexia. Compared with the lowest quartile, the adjusted ORs of dyslexia risk for the highest quartile of urinary diethylthiophosphate (DETP) and diethylphosphate (DEP) were 1.82 (1.04, 3.20) and 1.85 (1.08, 3.17), respectively. In addition, the adjusted ORs for dyslexia per 10-fold of urinary DEP, DETP, and ∑DEs concentration were 1.87 (1.12, 3.13), 1.55 (1.03, 2.35), and 1.91 (1.13, 3.21), respectively. Analyses stratified by gender indicated that such associations were more significant among boys. This study suggested that exposure to OP insecticides may be related to dyslexia among Chinese Han children from the three studied cities. However, our results should be interpreted with caution because of the case-control design and the fact that only one-spot urine sample was collected from the children. More studies with children living in China are necessary concerning the relatively high levels of urinary OP metabolites in our study.

Pediatric Exposures to Neurotoxicants: A Review of Magnetic Resonance Imaging and Spectroscopy Findings

Heavy metals, including lead and manganese, air pollution, pesticides, environmental tobacco smoke, and flame retardants are among the known and suspected environmental neurotoxicant exposures examined with magnetic resonance imaging (MRI)-based studies of pediatric populations. Many studies feature morphological changes associated with the exposures while others employ magnetic resonance spectroscopy, diffusion imaging, task-based, and resting state functional magnetic resonance imaging to reveal abnormal metabolic concentrations, white matter disorganization, and atypical patterns of activation. Some studies follow pregnant women and their offspring throughout the lifespan with collection of individual specimens as exposure biomarkers. Others innovatively make use of public databases to obtain relevant exposure biomarkers while taking advantage of these studies in their efforts to monitor developmental features in large, population-based, imaging cohorts. As exposures to neurotoxicants in the womb and throughout childhood have life-long impacts on health and well-being, the importance of these innovative neuroimaging investigations is ever increasing.

Association between Haematological Parameters and Exposure to a Mixture of Organophosphate and Neonicotinoid Insecticides among Male Farmworkers in Northern Thailand

Exposure to insecticides may result in various health problems. This study investigated the association between haematological parameters and exposure to a mixture of organophosphate (OP) and neonicotinoid (NEO) insecticides among male farmworkers in Fang district, Chiang Mai province, northern Thailand. Concentrations of urinary dialkylphosphates, non-specific metabolites of OPs, and NEOs and their metabolites and haematological parameters were measured in 143 male farmworkers. The Bayesian kernel machine regression model was employed to evaluate the associations. Exposure to a mixture of insecticides was significantly associated with the mean corpuscular haemoglobin concentration (MCHC) when the concentrations of all the compounds and their metabolites were at the 60th percentile or higher compared with the 50th percentile. Furthermore, exposure to clothianidin (CLO) showed a decreasing association with MCHC when all the other insecticides were at their mean concentrations. CLO was the most likely compound to reduce MCHC, and this was confirmed by sensitivity analysis. These findings suggest that exposure to NEO insecticides, especially CLO, affects the haematological status relating to haemoglobin parameters.

Evaluation of occupational pesticide exposure on Egyptian male adolescent cognitive and motor functioning

BACKGROUND

Chronic low-level exposure to organophosphorus pesticides is associated with adverse health effects, including a decline in neurological functioning and long-term impairment. These negative effects may be more detrimental in children and adolescents due to their critical stage in development. Little work has investigated the effects of chronic exposure to pesticides, specifically chlorpyrifos (CPF) during the adolescent period.

OBJECTIVES

To examine effects of CPF exposure over a year-long period within a group of male adolescents in Egypt (N = 242, mean age = 17.36), including both pesticide applicators and non-applicators.

METHODS

Associations between average CPF exposure (measured via urinary metabolite levels of 3,5,6-trichloro-2-pyridinol [TCPy]) and neurobehavioral functioning were examined in a 1-year longitudinal study. Given previous literature, higher levels of TCPy were expected to be associated with worse neurobehavioral functioning.

RESULTS

Using mixed effects linear regression, average TCPy exposure predicted deficits in more complex neurobehavioral tasks (Benton visual retention, digit span reverse, match to sample, serial digit learning, and alternating tapping) with estimates of effects ranging from -0.049 to 0.031. Age (effects ranging from 0.033 to 0.090) and field station (effects ranging from -1.266 to -0.278) were significantly predictive of neurobehavioral functioning over time. An interaction effect was found for field station and TCPy across several neurobehavioral domains.

DISCUSSION

Results show that occupational exposure to pesticides may have particularly deleterious effects on complex neurobehavioral domains. Additionally, differences across field stations and the age at which individuals are exposed may be important factors to investigate in future research.